High agility printing speed thermal printing equipment

Abstract

The present invention provides A coater (3) that coats the endless belt ribbon (5) with ink in a coating zone; a printhead (6) for thermally transferring a portion of the ink coated on the endless belt ribbon (5) onto a substrate (20) in a printing zone; a conveyor system (10, 11) for supporting and transporting an endless ribbon (5) containing ink along a first path from the coater (3) to the printhead (6) and a second path from the printhead (6) to the coater (3); a pre-printing buffer (8) for controlling the length of the first path of the ribbon in the coating zone; a post-printing buffer (7) for controlling the length of the second path of the ribbon within the print zone; This relates to a thermal transfer printing device (1).

Description

[Technical Field]

[0001] The present invention relates particularly to thermal transfer printing devices that include endless belt ribbons. [Background technology]

[0002] Current solutions involving thermal transfer printing equipment use disposable, pre-coated ribbons. One limitation of these solutions is the need to periodically replace the ribbon when it reaches its end. Such replacement requires the printer to be shut down for a period of time, which can be very inconvenient in some applications, such as when the printer is a labeling machine on a production line.

[0003] To overcome this drawback, EP 3055135 teaches a printing apparatus that uses an endless belt ribbon. Part of the belt ribbon is exposed to a thermal printhead, while the other part is exposed to a coater, transporting the belt ribbon on rollers while the printed ink is replaced. The goal is to use a ribbon that can withstand many cycles, e.g., millions of cycles through the system. This imposes robustness and reliability constraints on the ribbon configuration and system architecture.

[0004] A major drawback of such systems is the difficulty in meeting both coating and printing requirements.

[0005] In practice, coating requires a relatively constant speed, or at least avoiding sudden speed changes to achieve a uniform coating. Furthermore, the lower the coating speed, the longer the ribbon life and the higher the recoating energy required.

[0006] However, agility is required as the speed must be reduced between prints and then quickly accelerated to reach print speed. Furthermore, to increase print speed, and therefore the number of labels printed, the ribbon speed needs to be as fast as possible.

[0007] Because EP 3055135 teaches a belt ribbon, the ribbon speed cannot meet both requirements. Such a printer cannot provide both optimal coating and optimal printing with the high agility required to manage the speed difference.

[0008] EP 228866 A1 describes a printer with a buffer mechanism for buffering the movement of the ribbon. However, one drawback of this solution is that it increases the volume of the printer. Furthermore, this solution places high tension on the ribbon, which can cause damage to the ribbon. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] European Patent No. 3055135 [Patent Document 2] European Patent Publication No. 228866 Summary of the Invention [Means for solving the problem]

[0010] The present invention aims to provide a thermal transfer printing apparatus and related method to overcome the cited drawbacks.

[0011] According to a first aspect, the present invention provides a method for manufacturing a semiconductor device comprising: In the coating zone, a coater coats the endless belt ribbon with ink; a printhead in a print zone for thermally transferring a portion of the ink coated on the endless belt ribbon onto a substrate; a conveyor system that repeatedly supports and transports an endless ribbon containing ink along a first path from the coater to the print head and along a second path from the print head to the coater; a pre-print buffer for controlling the length of the first pass of the ribbon; A post-print buffer to control the length of the second pass of the ribbon; The present invention relates to a thermal transfer printing device including:

[0012] The two buffers, one on each side of the printhead, advantageously allow for a change in ribbon speed between the two buffers in relation to the ribbon speed in the coating zone. By simultaneously adjusting the length of both the first and second paths, the ribbon speed in the print zone can be different from and temporarily independent of the ribbon speed in the coating zone.

[0013] This allows the ribbon speed to be kept constant and slow during printing while the ribbon speed in the print zone is stopped or increased.

[0014] According to another aspect, a thermal transfer printing device includes: an endless ribbon having an inner surface and an outer surface; a coating device for coating the endless ribbon with ink in a coating zone; a printhead (6) for thermally transferring a portion of the ink coated on the endless ribbon onto a substrate in a printing zone; a conveyor system for supporting and transporting the endless ribbon along a path from the coating device to the print head and from the print head to the coating device; a pre-print buffer including at least two moving rollers for supporting the coated ribbon during transport from the coating device to the print head, the first moving roller being arranged to support an inner surface of the endless ribbon and the second moving roller being arranged to support an outer surface of the endless ribbon; a post-printing buffer including at least two moving rollers for supporting the ribbon during transport from the print head to the coating device, the third moving roller being arranged to support an inner surface of the endless ribbon and a fourth moving roller being arranged to support an outer surface of the endless ribbon; Equipped with.

[0015] In one embodiment, each moving roller is movable along a predetermined track, preferably in a plane sharply perpendicular to the axis of rotation of the moving roller.

[0016] In one embodiment, the printing device further comprises: Controlling the movement of the first moving roller and the second moving roller along a predetermined track to increase or decrease the length of the coated ribbon from the coating device to the print head; configured to control the movement of the third moving roller and the fourth moving roller along a predetermined track to increase or decrease the length of the ribbon after printing from the print head (6) to the coating device; Includes the first controller.

[0017] In one embodiment, both the first moving roller and the second moving roller of the same buffer are movable along a circular path about the same axis.

[0018] One advantage is that the amount or length of ribbon in the buffer zone is controlled by one unique motor that controls the rotation of the frame. Another advantage is that the volume of such a buffer is reduced, thereby reducing the volume of the printer.

[0019] In one embodiment, the printing apparatus further comprises a driver (optionally a drive roller) for driving the ribbon through the coating zone at a first speed.

[0020] In one embodiment, the printing apparatus further comprises a first controller configured to control movement of each roller along the predetermined trajectory; driving the ribbon in the print zone at a speed less than the first speed by driving a pre-print buffer to shorten the length of the ribbon along a first path and simultaneously driving a post-print buffer to lengthen the length along a second path; Driving the ribbon in the print zone at a speed greater than the first speed by driving the pre-print buffer to increase the length of the ribbon along a first path and simultaneously driving the post-print buffer to decrease the length along a second path.

[0021] The first controller advantageously automatically applies a speed differential between the speed of the ribbon in the print zone and the speed of the ribbon in the coating zone.

[0022] In one embodiment, the printing apparatus includes a print roller that holds and transports the substrate and ribbon along a print zone, the print roller and / or conveyor system being movable between two configurations: a print configuration and a detach configuration. The print configuration enables printing, and the ribbon is supported by contact with the substrate. In the print configuration, the ribbon is preferably sandwiched between the print head and the substrate. In the detach configuration, the ribbon detaches from the substrate, preferably from the print head.

[0023] In one embodiment, the printing apparatus further comprises a second controller capable of commanding the printing roller or conveyor system to change configurations between the printing and drop-off configurations.

[0024] In one embodiment, the printing device further comprises a velocity sensor that measures the velocity of the ribbon within the print zone.

[0025] The second controller can be configured to automatically command a change in configuration when the first controller fixes the ribbon on the print zone, or can be configured to control the print rollers to automatically switch drive roller configurations when the measured speed of the ribbon in the print zone is zero. In an alternative embodiment, the first controller is configured to automatically stop the ribbon on the print zone while the second controller changes the configuration.

[0026] Stopping the ribbon during a configuration change has the advantage that friction between the printhead and ribbon is avoided during the configuration change, preventing tears in the ribbon.

[0027] In one embodiment, the second controller automatically drives the print roller to drive the substrate at a speed that is the same as the ribbon speed in the print zone of the printing configuration, thereby reducing friction between the ribbon and the substrate.

[0028] In one embodiment, the pre-printing buffer and / or the post-printing buffer include at least moving rollers positioned and designed to hold and transport the ribbon along its path, each moving roller being movable along a predetermined track to change the length of the ribbon path.

[0029] In one embodiment, the transfer roller is movable along a circular track, which is advantageous for reducing the volume of the buffer and for increasing the difference between the maximum and minimum length of the ribbon path.

[0030] In one embodiment, the first axis is parallel to the axis of rotation of each moving roller of the at least one buffer, which is advantageous for providing a compact buffer.

[0031] In one embodiment, the printing apparatus further comprises an endless ribbon supported by the conveyor system along the first and second paths. The ribbon is preferably made of a material having a modulus of elasticity less than 3 GPa. This material advantageously allows the ribbon to be pulled by the buffer without plastic deformation.

[0032] In one embodiment, both the first and second moving rollers of the same buffer are mounted on a frame that is rotatably movable about an axis that is sharply parallel to the axes of rotation of the first and second moving rollers.

[0033] In one embodiment, the first controller is configured to control the pre-print buffer and the post-print buffer independently of each other.

[0034] In one embodiment, the first controller controls the buffer by controlling the rotation and direction of the frame of the buffer, optionally by controlling the motors of the frame.

[0035] According to another aspect, the invention relates to a method of printing a substrate with a thermal transfer printing apparatus, preferably a transfer printing apparatus according to the first aspect of the invention.

[0036] In one embodiment, the method includes driving the ribbon in the coating zone at a predetermined first speed while simultaneously driving the ribbon on the print zone at a second speed different from the predetermined first speed.

[0037] Driving the ribbon over the print zone at a second speed different from the predetermined first speed includes: Drive the moving roller of the pre-printing buffer to shorten the length of the ribbon from the coating device to the print head, and at the same time drive the moving roller of the post-printing buffer to lengthen the length of the ribbon from the print head to the coating device; Drive the moving roller of the pre-printing buffer to lengthen the ribbon length from the coating device to the print head, and at the same time drive the moving roller of the post-printing buffer to shorten the ribbon length from the print head to the coating device; This is carried out by:

[0038] In one embodiment, if the second speed is less than the first speed, the second speed is reached by driving the pre-printing buffer to increase the length of the ribbon along the first path and simultaneously driving the post-printing buffer to decrease the length along the second path.

[0039] This method has the advantage of being able to rapidly increase or decrease ribbon speed in the print zone while keeping ribbon speed constant in the coating zone, which advantageously results in more agile printing, more uniform coating, and improved ribbon life.

[0040] In one embodiment, the method further includes printing by: - Driving the ribbon in the coating zone at a predetermined speed To slow down the ribbon speed over the print zone, a pre-print buffer is driven to increase the length of the ribbon along a first path, and a post-print buffer is driven to decrease the length along a second path, · Move the print roller to the print position while slowing down the ribbon in the print zone.

[0041] In one embodiment, the method further includes operating the printing by driving the ribbon in the print zone at a printing speed.

[0042] In one embodiment, operating the printing further includes driving the ribbon speed in the print zone at a higher speed than the ribbon speed in the coating zone by driving a pre-printing buffer to shorten the length of the ribbon along a first path and simultaneously driving a post-printing buffer to increase the length along a second path.

[0043] In one embodiment, the method further comprises: - Driving the ribbon in the coating zone at a predetermined speed, reducing ribbon speed in the print zone by driving a pre-print buffer to shorten the length of ribbon along a first path and simultaneously driving a post-print buffer to lengthen the length along a second path; · Including releasing the print by moving the print roller to a disengagement position while the ribbon speed in the print zone is reduced. [Brief explanation of the drawings]

[0044] [Figure 1] FIG. 1 is a schematic diagram of a thermal transfer printing apparatus according to one embodiment, including an endless ribbon belt and two buffers, each buffer including movable rollers in a first configuration. [Figure 2] FIG. 2 is a schematic diagram of the thermal transfer printing apparatus of FIG. 1, with the movable roller in a second configuration. [Figure 3] FIG. 3 is a schematic diagram of the substrate conveyor system of the printing apparatus of FIGS. 1 and 2 in a printing configuration with the print rollers in a movable and printable position. [Figure 4] FIG. 4 is a schematic diagram of the substrate conveyor system of the printing apparatus of FIGS. 1 and 2 in a disengaged configuration in which the print rollers are movable and the ribbon is positioned disengaged from the substrate and printhead. [Figure 5] FIG. 5 is a schematic diagram of an alternative embodiment buffer in a first configuration. [Figure 6] FIG. 6 is a schematic diagram of the buffer of FIG. 5 in a second configuration. [Figure 7] FIG. 7 is a schematic diagram of a printing device according to an embodiment. [Figure 8] Figure 8 is a graph illustrating the printing of several labels in one embodiment of the present invention, showing the ribbon speed in both the coating and print zones, and the ribbon path length through both the pre-print and post-print buffers. [Figure 9] 9 is a graph illustrating the printing of one label in one embodiment of the present invention, showing the ribbon speed in both the coating and print zones, and the ribbon path length through both the pre-print and post-print buffers. [Figure 10] FIG. 10 is a schematic diagram of a substrate conveyor system for a printing apparatus according to another embodiment of the present invention, the printing apparatus including two additional buffers near the printhead. DETAILED DESCRIPTION OF THE INVENTION

[0045] The invention will be better understood from the following specification taken in conjunction with the drawings.

[0046] A preferred embodiment of a printing device 1 according to the present invention will be described with reference to FIGS.

[0047] The printing apparatus 1 comprises a coater 3 that applies ink to a ribbon and a printhead 6 that thermally transfers and prints a substrate onto which a portion of the ink has been applied to the ribbon. The printing apparatus 1 further comprises a conveyor system that is arranged and designed to hold and support the endless ribbon 5 along a path from the coater 3 to the printhead 6 and from the printhead 6 to the coater 3. The path of the ribbon defines a loop.

[0048] Coater The coater 3 is designed and arranged to apply ink to the outer surface of the ribbon 5 .

[0049] The coater 3 can be connected to a reservoir (not shown), which is designed to receive and supply solid ink to the coater 3. In another embodiment, the reservoir contains liquid ink and can be coupled with a mixing element to maintain the ink at a predetermined physical condition, such as temperature and / or viscosity.

[0050] The coater includes an outer surface that contacts the ribbon and can include an ink roller that is supplied with ink by a reservoir.

[0051] Alternatively, the coater 3 may include a slot die coating device positioned to coat the outer surface of the ribbon with ink.

[0052] The coater (also called a "coating apparatus") may include any coating system known to those skilled in the art and compatible with the present invention.

[0053] The coater 3 can be positioned in contact with or near the ribbon 5 to facilitate coating of the outer surface of the ribbon 5. By "outer surface," it should be understood that the surface of the ribbon facing outward from the ribbon loops, as opposed to the inner surface, is intended. The coater 3 is designed to deposit a layer of hot melt ink on the outer surface of the ribbon 5. The layer of liquid ink is preferably uniformly distributed on the surface of the ribbon 5. Ink control components (not shown) can ensure sufficient ink distribution on the surface of the ribbon 5 as a function of the speed of rotation / displacement of the ribbon 5 and / or the printing mode. The hot melt ink is applied to the ribbon 5 by the coater 3 above the coating zone. In one embodiment, the coating zone is defined by contact between the ribbon and the coater. Preferably, the coating zone is defined by a portion of the path of the endless ribbon where the hot melt ink is coated on the ribbon 5. The speed of the ribbon within the coating zone can therefore be defined by the time interval within the coating zone, i.e., the time interval during which the melted ink is applied to the ribbon 5, and the distance the ribbon travels along that path.

[0054] Preferably, the printing apparatus 1 comprises a support 11 that holds the ribbon 5 on which the ink is deposited, to ensure sufficient mechanical stability of the ribbon 5 during coating. In the embodiment shown in Figure 1, the support is a roller. In one embodiment, the ribbon in the coating zone is sandwiched between the coater 3 and the support 11. In one embodiment, the coating zone is defined by the portion of the ribbon path in which the ribbon is supported by the support 11.

[0055] The support 11 may include a roller, preferably a drive roller.

[0056] The reservoir and / or coater 3 may each include a heating device to melt the ink in the reservoir and / or coater 3. The reservoir may be filled with solid ink. When the solid ink comes into contact with the reservoir or coater 3, the ink is easily melted.

[0057] In one embodiment, printing apparatus 1 includes a device for periodically adding new solid ink to the reservoir.

[0058] print head The printing device 1 includes a printhead 6. In a preferred embodiment, the printhead 6 is a thermal transfer printhead 6.

[0059] Print rollers 21 can be used to transport substrate 2 near ribbon 5. Thermal transfer print head 6 is used to transfer hot melt ink from ribbon 5 to substrate 2. Print rollers 21 can be designed and positioned to hold and transport ribbon 5 and substrate 2.

[0060] In one embodiment, the print zone is defined by the portion of the ribbon path where the ribbon 5 is held and supported by the print roller 21. In one embodiment, the print zone is defined by the portion of the ribbon path where the ribbon 5, and in particular its outer surface, contacts the substrate 2. In one embodiment, the print zone is defined by the portion of the ribbon path where the ink coated on the ribbon 5 is transferred to the substrate 2.

[0061] The speed of the ribbon in the print zone may therefore be defined by the distance that the ribbon travels along its path during a time interval in the print zone, i.e., during which the coated ink on the ribbon is applied to the substrate 2.

[0062] The printhead 6 preferably includes a microheater area. The microheater area contacts the ribbon, particularly its inner surface, in the print zone and heats the ribbon and the ink thereon. The heated ink is then transferred to the substrate. The surface of the microheater area is 500 μm. 2 to 100,000 μm 2 , preferably 10,000 μm 2 to 20,000 μm 2 The width of the microheater region ranges from 40 μm to 300 μm. The length of the microheater region ranges from 1 to 2 times the width of the microheater region. The printhead 6 is preferably positioned so that the length axis of the microheater region is substantially parallel to the transport axis of the ribbon within the print zone.

[0063] During printing, the printhead 6 or microheater area contacts the inner surface of the ribbon 5 and allows heat transfer to the ink located on the outer surface of the ribbon 5 .

[0064] In one embodiment, the printhead includes a protective layer on the surface of the microheater region. In this embodiment, the inner surface of the ribbon 5 slides against the protective layer during printing. The microheater region heats the protective layer and the ink on the ribbon through the thickness of the ribbon 5.

[0065] The protective layer can comprise a sol-gel material, preferably a borosilicate. The protective layer advantageously protects the ribbon from friction. The thickness of the protective layer favors heat conduction. The thickness of the protective layer ranges from 1 to 50 μm. The protective layer can comprise a sol-gel material, preferably a borosilicate. Such a material is advantageous for avoiding high friction between the ribbon and the printhead while the ribbon slides over the printhead during printing.

[0066] In this printing process, the outer surface of the ribbon 5 contacts the substrate 2 and transfers a portion of the ink intended for printing onto the substrate.

[0067] The print roller 21 ensures sufficient pressure on the substrate 2 to maintain contact with the ribbon 5 as the printing process takes place, and maintains the ribbon 5 in a moving sandwich between the substrate 2 and the print head 6 (or microheater area) during the printing process. The movement of the substrate 2 is in the same direction as the displacement of the ribbon 5 adjacent to the print head 6. Preferably, both the substrate 2 and the ribbon 5 adjacent to the print head 6 are linear movements.

[0068] In another embodiment, the printhead 6 includes a laser that heats the ink through the thickness of the ribbon 5 to enable heat transfer 6 of the ink located on the outer surface 51 of the ribbon 5. The wavelength of the laser is preferably between 950 nm and 1450 nm.

[0069] The alignment between the print head 6, ribbon 5, and substrate 2 may be ensured by precisely set mechanical components depending on the desired printing accuracy. Several guides and position control components may be implemented to ensure a predetermined alignment between at least the print head 6 and ribbon 5. For example, a deflector 23 may be used to at least partially support the substrate 2.

[0070] ribbon The ribbon 5 is designed to be implemented in the printing device 1 of the present invention. The ribbon 5 allows the transport of ink from the coater 3 to the printhead 6 on its outer surface. The ribbon 5 is an endless ribbon. By endless ribbon, we mean a ribbon or belt ribbon that forms a loop. Such ribbons are then coated and used repeatedly for printing. Residual ink not used during the printing process passes through the printhead and is transported to an ink recovery device (not shown) where it is reapplied. As a result, the same ribbon 5 is used continuously to transport ink for printing and residual ink after printing. The printing process is implemented to form a continuous loop process in which residual ink is automatically recovered. This configuration allows unused ink to be recovered. This ink can be advantageously reapplied and reused on the next turn of the ribbon 5.

[0071] One advantage of the present invention is that it provides an autonomous printing device in which at least a portion, preferably 100% or substantially 100% of the ink is used, i.e., there is no ink loss.

[0072] The ribbon 5 can be made from a variety of materials. The ribbon 5 is preferably made from a material with high heat resistance, such as heat resistance up to 300°C, and high chemical resistance, such as resistance to alcohol, ink, and solvents. Preferably, the ribbon 5 is a polyimide film. Polyimide can be used in temperatures ranging from 340°C to 380°C without deformation of the ribbon. In a preferred embodiment, the ribbon 5 can be made from a metal or metal alloy. The ribbon 5 can be made from a metal alloy, such as stainless steel, aluminum alloy, titanium alloy, copper alloy, or beryllium alloy. In one embodiment, the ribbon can be made from an alloy containing nickel, tin, and copper, preferably between 14.5% and 15.5% nickel, between 7.5% and 8.5% tin, and between 75% and 79% copper.

[0073] In a preferred embodiment, the ribbon 5 is made of a material with an elastic modulus (also called Young's modulus) of 3 GPa or less, which has the advantage that the ribbon 5 can withstand the tension imposed by the conveyor system without damaging the ribbon.

[0074] Ribbon 5 is preferably made of a material that has a heat transfer coefficient greater than 0.120 watts per meter-Kelvin.

[0075] The thickness and composition of the ribbon material is designed to transfer heat through the ribbon enabling printing.

[0076] The thickness of the ribbon 5 is preferably less than 50 μm or 20 μm. This thickness has the advantage of lowering the heat transfer resistance between the inner and outer surfaces, improving print quality. The thickness of the ribbon 5 can be substantially between 0.5 μm and 50 μm, and most preferably between 0.5 μm and 20 μm. In one example, the thickness of the ribbon 5 is selected in the range of [3-25 μm] or [5-10 μm].

[0077] In one embodiment where printhead 6 includes a laser, ribbon 5 is transparent at the wavelength of the laser. In this example, the thickness of ribbon 5 is selected in the range [3-200 μm].

[0078] Conveyor System The ribbon 5 is held and transported using a conveyor system that supports and transports the ribbon 5 along its path.

[0079] The conveyor system may include at least one roller 10 for holding and transporting the endless ribbon 5. The conveyor system may be made up of multiple rollers 10, 11 for holding and transporting the endless ribbon 5 along its path.

[0080] At least one of the rollers may be a drive roller 11. The drive roller 11 is connected to a motor that rotates the drive roller 11. At least one battery or electrical circuit may be implemented in the printing device to power the motor. The rotation of the drive roller 11 causes the displacement of the endless ribbon 5 along its path and also causes the rotation of the other rollers 10.

[0081] The rollers 10, 11 are mounted to the frame of the printing apparatus so as to rotate on their own and transport the ribbon along their circumferential surfaces. The rollers 10, 11 have a cylindrical shape and are mounted to the frame of the printing apparatus so as to rotate about their longitudinal axes.

[0082] In one embodiment (not shown), the conveyor system includes at least one conveyor belt. The conveyor belt is designed and positioned to support and transport the ribbon 5 on its inner surface along a portion of the ribbon's path. The conveyor belt functions similarly to a continuous track, rotating the ribbon 5 in one direction. In one embodiment, the conveyor belt includes a looped parallelogram foam sheet to form a ribbon support. The conveyor belt may be supported by at least two rollers. In another example, the conveyor belt is supported by three rollers, forming a triangle. One advantage of a conveyor belt is that the ribbon 5 is transported along the distance between the two rollers without undergoing mechanical deformation. The conveyor belt minimizes stress on the ribbon 5, improving the lifespan of the ribbon 5. Furthermore, minimizing stress on the ribbon 5 avoids the creation of a ripple profile in the ribbon 5. Furthermore, using a belt conveyor reduces the risk of wrinkles or shifting of the ribbon 5.

[0083] isolation wall In one embodiment, the printing apparatus 1 comprises a frame. The frame includes the coater 3, the print head 6, the conveyor system, and the path of the ribbon 5. The frame includes at least one opening for the exit of the printed substrate 2. In one embodiment, the printing apparatus 1 further includes an isolation wall 4. The isolation wall 4 is positioned to isolate the zone including the coater 3 from the rest of the apparatus. Isolation wall 4 may include an opening for the passage of the ribbon 5. One advantage is that it contains the heat provided by the coater 3. The coated ink tends to solidify on the ribbon during transport from the coater to the print zone.

[0084] double buffering The printing apparatus 1 comprises buffers 7, 8. The buffers define zones within which a portion of the ribbon path is controlled by the buffer. The buffers are capable of controlling the ribbon path such that the length of the ribbon path within the zone defined by the buffer or through the buffer can be increased or decreased. Thus, the buffers are constructed and arranged to shorten or increase the length of a portion of the ribbon path.

[0085] The ribbon 5 is transported along a path consisting of a first path (from the coating zone to the print zone) and a second path (from the print zone to the coating zone).

[0086] The first pass of the ribbon is through coater 3 (or coating The first path of the ribbon comprises the re-inked portion of the ribbon (also called "re-inked" ribbon) that is transported from the first path (or print zone) to the print head 6 (or print zone). The second path of the ribbon comprises the other portion of the printed ribbon (also called "printed-ribbon"), or the ink remaining after printing, that is transported from the print head (or print zone) to the coater 3 (or coating zone).

[0087] The printing device 1 according to the present invention includes a pre-printing buffer 8 in the first path of the ribbon and a post-printing buffer 7 in the second path of the ribbon. Thus, the pre-printing buffer 8 controls the length of the first path of the ribbon and the post-printing buffer 7 controls the length of the second path of the ribbon.

[0088] That is, the pre-print buffer 8 is designed to buffer a predetermined portion of the re-inked ribbon, and the post-print buffer 7 is designed to buffer a predetermined portion of the printed ribbon.

[0089] By "designed to buffer" it should be understood that each buffer is designed to store therein a variable amount or length of ribbon, the length of which can be defined between the entrance and exit of said pre-printing buffer 8 or post-printing buffer 7.

[0090] In a preferred embodiment, the driver 11 is positioned to drive the ribbon 5 at a first speed over the coating zone. The driver 11 is preferably positioned between the pre-printing buffer 8 and the post-printing buffer 7, on the coating zone side.

[0091] Two buffers 7, 8 on either side of the print zone advantageously make it possible to drive the ribbon 5 on the print zone at a second speed different from the first speed of the ribbon in the coating zone driven by the driver 11.

[0092] Indeed, if the length of the first path is shortened by the pre-print buffer 8 and at the same time the length of the second path is lengthened by the post-print buffer 7, the speed of the ribbon 5 above the print zone is greater than the speed of the ribbon in the coating zone.

[0093] On the other hand, if the length of the first path is increased by the pre-printing buffer 8 and the length of the second path is simultaneously decreased by the post-printing buffer 7, the speed of the ribbon above the print zone is less than the speed of the ribbon in the coating zone.

[0094] buffer The buffers 7, 8 preferably include moving rollers 71, 81 positioned to hold and transport the ribbon 5. The positions of the rollers 71, 81 define the path of the ribbon 5 through the buffers 7, 8. In one embodiment, each buffer 7, 8 includes at least one moving roller positioned to support the ribbon on an inner surface and at least one moving roller positioned to support the ribbon on an outer surface. Each moving roller 71, 83, 73, 81 is mounted for rotation on the frame of the printing apparatus and transports the ribbon along its circular periphery. Each moving roller 71, 83, 73, 81 has a cylindrical shape and is mounted to the frame of the printing apparatus for rotation about its longitudinal axis.

[0095] Furthermore, each moving roller is also free to move along a predefined track 72, 82, 92.

[0096] Moving roller 71、81、91 As the moves along the predefined trajectory 72, 82, 92, the amount of ribbon stored in the buffer or the length of ribbon between the inlet and outlet of the buffer increases or decreases.

[0097] As shown in Figures 1 and 2, the pre-printing buffer is composed of a first moving roller 81 that supports the inner surface of the ribbon 5 and a second moving roller 83 that supports the outer surface of the ribbon 5. After printing The buffer 7 is composed of a third movable roller 71 that supports the inner surface of the ribbon 5 and a second movable roller 73 that supports the outer surface of the ribbon 5. Each buffer is composed of one roller on each side of the ribbon, which has the advantage that the length of the ribbon can be increased or decreased by moving the roller.

[0098] In one embodiment, rollers 71, 81, 73, 83 are movable along predetermined tracks 72, 82. By movable, it should be understood that the axis of rotation of roller B is free to translate or rotate along the predetermined track, preferably in a plane nominally perpendicular to the axis of rotation B, which corresponds to the longitudinal axis of said roller.

[0099] The movement of the rollers induces a change in the ribbon path, which can therefore be shortened or lengthened.

[0100] That is, movement of the roller changes the amount of ribbon stored between the entrance and exit of the buffer.

[0101] Thus, in one example, increasing or decreasing the amount of ribbon stored between the entrance and exit of the pre-print buffer increases or decreases the length of the inked ribbon, respectively.

[0102] In a second example, increasing or decreasing the amount of ribbon stored between the entrance and exit of the post-printing buffer increases or decreases the length of the printed ribbon, respectively.

[0103] In one embodiment, an increase or decrease in the inked ribbon length automatically decreases or increases the printed ribbon length, respectively.

[0104] In the first embodiment shown in FIGS. 1 and 2, the buffers 7 and 8 each Two rollers 71 and 73 , 81 and 83 It is equipped with: Each Both rollers of the buffer 71 and 73 , 81 and 83 can move along predefined trajectories (dotted lines) 72, 82. The movements of the rollers of the same buffer may be synchronized or simultaneous.

[0105] As shown in Figure 1, the pre-print buffer 8 is in a long configuration where the length of the first path is maximum. As shown in Figure 2, the rollers 81 of the pre-print buffer 8 can be displaced to a short configuration where the length of the first path is minimum. In one embodiment, the ratio of the maximum length to the minimum length of the ribbon path between the buffer entrance and exit is greater than 1.3, preferably between 1.3 and 3.

[0106] 1 and 2 show an embodiment in which rollers 71, 81 of buffers 7, 8 can move along circular tracks 72, 82. Both rollers rotate about the same axis to "wind" or "unwind" the ribbon 5 within the buffer zone, increasing or decreasing the length of the ribbon in the first or second pass, respectively. This buffer embodiment is advantageous for providing a compact buffer in both long and short configurations. A "buffer zone" can be defined between the buffer's entrance and exit. The buffer's entrance and exit, or the limits of the buffer zone, can be defined by two adjacent rollers 10 on either side of the buffers 7, 8, 9. For example, the buffer zone entrance is defined by contact between the ribbon and the roller in front of the buffer, and the buffer zone exit is defined by contact between the ribbon and the roller in back of the buffer.

[0107] The terms "front roller" and "rear roller" are used herein to refer to the ribbon 5 ribbon before and after the buffering system according to the transport direction 5 This should be understood as the nearest roller of the conveyor system 2 supporting the

[0108] In other embodiments, the entrance of the pre-printing buffer is the coating zone and the exit of the pre-printing buffer is the print zone. Thus, the exit of the post-printing buffer is the coating zone and the entrance of the post-printing buffer is the print zone.

[0109] figure 7 shows an embodiment of such a buffer. The buffer includes a frame 84. The frame is mounted to the printing apparatus with one degree of freedom, rotation about axis A. The frame 84 may include a pivot 85 about which the frame can rotate.

[0110] Roller 81 is mounted to frame 84. Roller 81 is mounted to frame 81 with one degree of freedom to rotate about axis B for transporting ribbon on its outer surface. In one embodiment, axis of rotation A of frame 84 is parallel to axis of rotation B of roller 81.

[0111] Thus, the rotation of the frame 84 on the axis A rotates both rollers 81 along the curved path 82. and 83 This trajectory allows winding or unwinding of ribbon 5 to increase or decrease the path of the ribbon, respectively, depending on the direction of rotation of frame 84. This embodiment advantageously allows both rollers 81 of the same buffer 8 to be moved simultaneously. and 83 The present invention provides a buffer 8 in which only one motor is required to move the buffer 8 along the predetermined trajectory 82. The number of motors can be advantageously reduced and the printing device 1 is advantageously less complex and more compact.

[0112] Another embodiment of the buffer 9 is shown in Figures 5 and 6. In this embodiment, the roller 91 and 93 Each of the rollers 91 can move along a linear track 92. and 93 5, all of the rollers 91 are movable along a track 92 between a first position and a second position. and 93 When the rollers 91 are positioned in the first position, the buffer 9 is in a long configuration and the length of the ribbon path through the buffer is maximized. and 93 When is positioned in the second position, the buffer is in a short configuration and the length of the ribbon path through the buffer is minimized.

[0113] In one embodiment, the buffer includes rails that guide the rollers 71, 81, 91 along a predetermined track.

[0114] The simultaneous movement of the two moving rollers 71, 81 causes an increase or decrease in the amount or length of ribbon within the buffer zone, since each moving roller is positioned to support opposite sides of the ribbon. Furthermore, the two moving rollers move along the same direction of a circular path about the same axis A, thereby allowing the buffer to be compacted with respect to differences in the amount or length of ribbon stored within the buffer zone.

[0115] First Controller In one embodiment, the printing device 1 comprises a first controller CALC, which controls both the pre-printing buffer 8 and the post-printing buffer 7. In one embodiment, the buffers are controlled by manipulating first and second moving rollers of the buffers along predetermined tracks.

[0116] In one embodiment, the first controller controls the moving rollers 71, 81, 91 to move along a predetermined track. 72、82、92 In one embodiment, each buffer includes at least one motor for moving its rollers 71, 81, 91 along a predetermined track, and the first controller controls the motor.

[0117] 1 and 2, to control the length of the reinked or printed ribbon, the first controller causes a rotation of the frame 84 of the pre-printing buffer 8 or post-printing buffer 7, respectively. The direction of rotation of the frame 84 determines whether the amount of ribbon stored in the buffer zone increases or decreases.

[0118] Each buffer preferably comprises a motor MT connected to a frame 84 to cause rotation of the frame about its pivot 85. The motor MT is controlled by a first controller CALC. The first controller CALC is thus configured to control the motor MT. The first controller CALC is therefore configured to control the rotation of the frame 84 and to control the direction of rotation of the frame 84.

[0119] The first controller CALC is configured to control both buffers to drive the ribbon on the print zone at a speed that is less than the first speed of the ribbon on the coating zone by driving the pre-print buffer 8 to increase the length of the ribbon along a first path and simultaneously driving the post-print buffer 7 to decrease the length along a second path.

[0120] The first controller CALC is configured to control both buffers to drive the ribbon on the print zone at a speed greater than the first speed of the ribbon on the coating zone by driving the pre-print buffer 8 to shorten the length of the ribbon along a first path and simultaneously driving the post-print buffer 7 to lengthen the length along a second path.

[0121] Control of the buffer is achieved by controlling the movement of rollers which move along predetermined tracks 72,82.

[0122] By driving both buffers simultaneously, it is possible to simultaneously increase the ribbon path length on one side of the print zone and decrease the ribbon path length on the other side of the print zone, i.e., one of the two buffers is used to control the ribbon speed in the print zone and the other buffer is used to compensate for the ribbon path length to avoid increasing tension along the ribbon on one side of the print zone.

[0123] That is, by decreasing the amount or length of ribbon stored between the entrance and exit of the pre-print buffer 8 while simultaneously increasing the amount of ribbon stored between the entrance and exit of the post-print buffer 7, the speed of the ribbon in the print zone becomes faster than the speed of the ribbon in the coating zone. Alternatively, by increasing the amount of ribbon stored between the entrance and exit of the pre-print buffer 8 while simultaneously decreasing the amount of ribbon stored between the entrance and exit of the post-print buffer 7, the speed of the ribbon in the print zone becomes slower to the speed of the ribbon in the coating zone.

[0124] In one embodiment, the first controller further controls the speed of the ribbon in the coating zone by controlling the driver of the conveyor system (eg, the rotation of drive roller 11).

[0125] In one embodiment, the first controller CALC is configured to control the pre-printing buffer and the post-printing buffer independently of each other. Indeed, during printing, the ribbon is clamped between the print head 6 and the substrate 2, and between the drive roller 11 and the coater 3. Therefore, the tension on the ribbon may not be the same on both sides of the print head. One advantage of the independent control of the buffers 7, 8 is to avoid excessive tension on one of the two sides of the ribbon during printing.

[0126] Printing and Breakout Configuration As shown in Figures 1-4, the printing apparatus 1 includes a substrate 2 that is transported in contact with the ribbon through a print zone to enable heat transfer of ink from the ribbon to the substrate. The printing apparatus may further include substrate rollers 22, 23 for holding and supporting the substrate. The printing apparatus may also include a print roller 21 for holding and transporting the substrate in contact with the ribbon through the print zone, as previously described herein.

[0127] In one embodiment, the printing device is designed to provide two configurations: a printing configuration and a take-off configuration.

[0128] In the printing configuration shown in FIG. 3 , the ribbon 5 is supported by contact with the substrate 2. The ribbon 5 is supported through the substrate 2 by the print roller 21. By "supported through the roller by the print roller," it should be understood that the print roller 21 supports the ribbon 5, and the substrate 2 is located between the ribbon 5 and the print roller 21. In the printing configuration, the print roller 21 ensures sufficient pressure on the substrate 2 to maintain contact with the ribbon 5 during printing. This advantageously facilitates the transfer of ink from the ribbon 5 to the substrate 2.

[0129] In one embodiment, in the printing configuration, print roller 21 maintains ribbon 5 in contact with substrate 2 and, optionally, print head 6 or microheater areas of print head 6 .

[0130] In the printing configuration, the ribbon preferably travels along its path in contact with a protective layer of the printhead. The protective layer can conduct heat from the microheater regions, advantageously preventing ribbon tearing. This allows the ink to be heated through the ribbon, melting the ink and allowing it to transfer from the ribbon 5 to the substrate 2. The speed of the ribbon in the print zone can therefore be defined by the time interval in the print zone, i.e., the distance the ribbon travels along its path when the ink coated on the ribbon is applied to the substrate 2 by thermal transfer.

[0131] In an alternative embodiment where the printhead 6 includes a laser for heating the ink, the ribbon 5 is not in contact with the printhead 6 in the printing configuration.

[0132] In one embodiment, the printing apparatus 1 includes a driver that drives the substrate 2. By "driving the substrate" it should be understood that it is controlling the movement of the substrate and its speed along its path. The driver may be a print roller 21. The printing apparatus 1 includes a motor connected to the print roller 21 to rotate the roller and transport the substrate 2 along its path. The driver may be used to transport the substrate 2 adjacent to the ribbon 5.

[0133] 4, in the detached configuration, the ribbon 5 is detached from the substrate 2. In such a configuration, printing or thermal transfer of ink from the ribbon 5 to the substrate 2 is not possible. In the detached configuration, the ribbon 5 does not contact the printhead 6. Therefore, in either configuration, the velocity of the ribbon in the print zone may be defined by the distance the ribbon travels along its path during the time interval that the ribbon is between the substrate 2 and the printhead 6.

[0134] In one embodiment, an element of the printing device is movable to switch the printing device from a printing configuration to a take-off configuration or from a take-off configuration to a printing configuration. This element may be a roller 10 of a movable conveyor system. As shown in Figures 3 and 4, this element may be a printing roller 21. The printing roller 11 is movable between two positions: a first position corresponding to the printing configuration and a second position corresponding to the take-off configuration.

[0135] Second Controller The printing apparatus 1 may comprise a second controller COMP configured to control the movable element to switch between a printing configuration and a take-off configuration.

[0136] In Figures 3 and 4, where the element is a print roller 21, a second controller controls the movement of the print roller 21 between two positions.

[0137] In one embodiment, the second controller COMP is configured to automatically switch the configuration of the printing device 1 when the speed of the ribbon 5 in the print zone is null while the speed of the ribbon 5 in the coating zone is non-zero, thereby allowing the ribbon 5 in the print zone to be stopped when the printing device 1 switches configuration.

[0138] Thus, when the ribbon 5 contacts or leaves the microheater area of ​​the printhead, the velocity of the ribbon 5 is zero and there is no friction between the ribbon and the printhead, which advantageously reduces the risk of tearing.

[0139] In a printing configuration, it is desirable to control the print rollers 21 to automatically transport the substrate at the same speed as the ribbon in the print zone.

[0140] In one embodiment, the first and second controllers are one unique computer or are connected to one unique user interface. In one embodiment, the first and / or second controller further controls the printhead 6.

[0141] The first controller CALC is connected to the drive roller 11 of the conveyor system or the motor of the drive roller to drive the rotation of the drive roller 11 and thereby drive the speed of the ribbon in the coating zone. The first controller CALC is also connected to the buffers 7, 8 or the moving rollers 71, 81, 73, 83 of the buffers to control the speed difference between the speed of the ribbon in the coating zone and the speed of the ribbon in the printing zone.

[0142] The first controller CALC and / or the second controller COMP may comprise a computer readable memory or any readable medium containing a computer program comprising instructions for causing the printing device to perform the steps of the method according to the invention. The first controller may comprise a processor or a computer configured to cause the printing device to perform the steps of the method according to the invention.

[0143] The first controller CALC and the second controller COMP can control the transfer rollers and / or the drive rollers 11 and / or the printing rollers 21 according to instructions received by the communication means, which can include measurements by sensors such as speed sensors configured to measure the speed of the substrate 2 and / or the speed of the ribbon in the coating zone and / or the printing zone.

[0144] Additional Buffering In one embodiment shown in FIG. 10, the thermal transfer printing device comprises two additional buffers 101,110.

[0145] The additional buffer comprises rollers 104 on arms 103. The additional buffer is arranged to support the ribbon on the rollers 104 of the additional buffer.

[0146] The arm 103 of the additional buffer is pivotally movable about an axis 102. The pivoting drives a roller 104 between at least a first position N and a second position M.

[0147] In the first position N, the roller defines a path for the ribbon that is shorter than the path for the ribbon when the roller is in the second position M.

[0148] Preferably, the additional buffers 101 , 110 are arranged between the pre-printing buffer 8 or the post-printing buffer 7 and the printhead 6 .

[0149] Each additional buffer, like the pre-printing buffer 8 and the post-printing buffer 7, is intended to control the length of the ribbon. A first additional buffer 101 is located between the pre-printing buffer 8 and the printhead 6 and controls the length of the ribbon between the pre-printing buffer 8 and the printhead 6. A second additional buffer 110 is located between the post-printing buffer 7 and the printhead 6 and controls the length of the ribbon 5 between the post-printing buffer 7 and the printhead 6.

[0150] In one embodiment, the difference in ribbon path length between the first position N and the second position M is less than the difference in ribbon path length achievable by the post-printing buffer 7 or the pre-printing buffer 8 .

[0151] In a first configuration, the first additional buffer 101 is at a first position N and the second additional buffer 110 is at a second position M (dotted lines in FIG. 10). In a second configuration, the first additional buffer 101 is at a second position M and the second additional buffer 110 is at the first position N.

[0152] By simultaneously switching the additional buffers and moving the first additional buffer 101 from the first configuration to the second configuration, the system can temporarily stop the speed of the ribbon in the print zone, thereby allowing the print roller 21 to move to the printing configuration or the release configuration while the ribbon is stationary, reducing damage to the ribbon and improving its lifespan.

[0153] In one embodiment, the pivot 102 of the arm 103 comprises a torsion spring. One advantage of a torsion spring is that it allows the roller 104 to switch between the first and second positions very quickly.

[0154] How to print the circuit board According to a second aspect, the present invention further relates to a method of printing a substrate. Preferably, the method of printing a substrate comprises providing a printing apparatus according to the present invention.

[0155] Next, an embodiment of a method for printing a substrate according to the present invention will be described with reference to FIGS.

[0156] 9 and 8 show graphs of the ribbon speed in the coating zone SC and the ribbon speed in the print zone SP, the ribbon path length through the pre-print buffer PRB and the ribbon path length through the post-print buffer POB.

[0157] In Phase A, the printing device is in an isolated configuration. The ribbon is transported along its path. The ribbon is coated with ink as it passes through the coating zone. During Phase A, the speed SC is increased to a predetermined first speed S1. At the end of Phase A, the speeds SC and SP should be equal. This means that no buffer is increasing or decreasing the length of the ribbon path through the buffer. This has the advantage of allowing the ribbon to be evenly coated before printing.

[0158] In Phase B, the printing device is moved into the printing configuration. As previously mentioned, the printing roller 21 may be moved to press against the ribbon and support the substrate.

[0159] In one embodiment, in the printing configuration, print roller 21 maintains ribbon 5 in contact with printhead 6 or the microheater areas of the printhead or the protective layer of printhead 6 .

[0160] During the switchover to the printing configuration, the print roller 21 applies a force between the ribbon and the printhead. This force increases the friction between the printhead and the ribbon. This friction increases the risk of ribbon tearing. To avoid this, phase B can comprise stopping the ribbon in the print zone. As shown in FIG. 9, the speed SC is maintained at a first predetermined speed S1 while the speed SP is reduced to zero. It can be seen from FIG. 9 that this speed difference between SC and SP is achieved by driving the pre-printing buffer 8 to increase the length of the ribbon along the first path PRB and simultaneously driving the post-printing buffer 7 to decrease the length of the ribbon along the second path POB. It is desirable to increase the length PRB and decrease the length POB as a function of the speed SC so that the speed SP becomes zero.

[0161] "Driving a buffer" can be understood as controlling the movement of the moving rollers of said buffer in order to shorten or lengthen the path length of the ribbon.

[0162] Such a phase B allows the ribbon to be stopped while maintaining contact between the ribbon and the printhead. Stopping the ribbon during such a configuration change therefore advantageously prevents tearing of the ribbon in contact with the printhead. Indeed, when the print roller applies force to the ribbon, no friction occurs between the ribbon and the printhead if the ribbon is stopped.

[0163] In one embodiment, during phase B, the substrate is transported at a velocity equal to velocity SP. This reduces friction while maintaining contact between the ribbon and the substrate, advantageously reducing the risk of tearing or damaging the ribbon.

[0164] This method and printing apparatus has the advantage that the ribbon and print zone can be stopped without changing the speed over the coating zone.

[0165] Preferably, during phase A, the pre-printing buffer 8 is controlled to increase the length of the first pass or path of the ribbon through the pre-printing buffer 8, and the post-printing buffer 7 is controlled to decrease the length of the second pass or path of the ribbon through the post-printing buffer 7. This advantageously prepares the buffer for the next phase B.

[0166] Phase C corresponds to the printing step. During printing, the speed SP can be made faster than the speed SC by driving the pre-printing buffer 8 to shorten the length of the ribbon along the first path PRB and simultaneously driving the post-printing buffer 7 to lengthen the length along the second path POB. The speed SP may be constant during printing at a predetermined second speed S2.

[0167] This has the advantage that high printing speeds can be provided without changing the coating zone speed SC.

[0168] In a first embodiment, printing is short, as shown in Figure 9. For example, phase C includes printing one unique label. In that embodiment, speed SC may be maintained at a predetermined first speed S1 that is less than a predetermined second speed S2 during printing.

[0169] In a second alternative embodiment shown in Figure 8, the printing is longer. For example, Phase C includes printing multiple labels in succession. In this second embodiment, the coating zone speed SC is gradually increased during printing of Phase C until it reaches print speed S2. It is desirable to control the buffer to maintain the print zone speed SP at a constant speed while speed SC is increased.

[0170] During Phase D, the printing apparatus moves to the disengagement configuration. As previously described, the print roller 21 can be moved so that the ribbon does not contact both the print head and the substrate. During this Phase D, as described in Phase B, the ribbon speed is preferably reduced to zero. This avoids friction between the ribbon, the substrate, and the print head while the ribbon is disengaging from the print head.

[0171] In phase E, the printing device is in the disengaged configuration. In this phase, the buffer is driven so that speed SP equals speed SC. In one embodiment, shown in Figure 8, coating zone speed SC is gradually reduced until it reaches a predetermined first speed S1.

[0172] During printing (phase C), the ribbon may be held by its two faces at two locations in the ribbon path: the coating zone (between the coater and the substrate) and the print zone (between the print head or microheater area and the print roller 21). These zones divide the ribbon path into two parts: a first path from the coating zone to the print zone, where the ribbon transports coated ink, and a second path from the print zone to the coating zone, where the ribbon transports unprinted ink.

[0173] Thus, the tension in the ribbon along the first path may be different from the tension in the ribbon along the second path, and so the torque applied to the moving roller of one buffer may be different from the torque simultaneously applied to the moving roller of the other buffer.

[0174] In another embodiment, the rate at which the ribbon path length is increased in one buffer may not be exactly equal to the rate at which the ribbon path length is decreased in the other buffer.

Claims

1. an endless ribbon (5) with an inner surface and an outer surface; a coating device (3) for coating the endless ribbon (5) with ink in a coating zone; a printhead (6) for thermally transferring a portion of the ink coated on the endless ribbon (5) onto a substrate (2) in a printing zone; a conveyor system (10, 11) for supporting and transporting the endless ribbon (5) along a path from the coating device (3) to the print head (6) and from the print head (6) to the coating device (3); a pre-printing buffer (8) for supporting the coated ribbon (5) during transport from the coating device (3) to the print head (6), comprising at least two moving rollers: a first moving roller (81) arranged to support the inner surface of the endless ribbon (5) and a second moving roller (83) arranged to support the outer surface of the endless ribbon; a post-printing buffer (7) including at least two moving rollers (71, 73) for supporting the ribbon (5) during transport from the print head (6) to the coating device (3), the third moving roller (71) being arranged to support the inner surface of the endless ribbon (5) and a fourth moving roller (73) being arranged to support the outer surface of the endless ribbon (5); Equipped with Each moving roller (71, 73, 81, 83) has a predetermined track (71, 73, 81, 83) in a plane sensibly perpendicular to the longitudinal axis of said moving roller (71, 73, 81, 83). 2, 82), ・The first controller (CALC) is - controlling the movement of the first moving roller (81) and the second moving roller (83) along a predetermined track (82) to increase or decrease the length of the coated ribbon path from the coating device (3) to the print head (6); configured to control the movement of the third moving roller (71) and the fourth moving roller (73) along a predetermined trajectory (72) to increase or decrease the length of the printed ribbon path from the print head (6) to the coating device (3); Thermal transfer printing device (1).

2. Both the first moving roller (81) and the second moving roller (83) of the pre-printing buffer (8) are movable along a circular path (82) centered on the same first axis (A), and / or both the third moving roller (71) and the fourth moving roller (73) of the post-printing buffer (7) are movable along a circular path (72) centered on the same second axis. A thermal transfer printing device (1) according to claim 1.

3. Both the first moving roller (81) and the second moving roller (83) of the pre-printing buffer (8) are mounted on a frame (84), the frame being rotatable about the first axis (A) which is sharply parallel to the rotation axes (B) of the first and second moving rollers, and / or the third moving roller (71) and the fourth moving roller (73) of the post-printing buffer (7) are mounted on a frame, the frame being rotatable about the first axis (A) which is sharply parallel to the rotation axes of the third and fourth moving rollers, A thermal transfer printing device (1) according to claim 2.

4. a drive roller (11) for driving the ribbon (5) at a first speed in the coating zone; The first controller (CALC) is configured to control the movement of each of the moving rollers (71, 73, 81, 83) moving along a predetermined track (72, 82); driving the ribbon in the print zone at a speed less than the first speed by driving the pre-printing buffer (8) to shorten the length of the ribbon from the coating device (3) to the print head (6) and simultaneously driving the post-printing buffer (7) to lengthen the length of the ribbon from the print head (6) to the coating device; driving the ribbon in the print zone at a speed greater than the first speed by driving the pre-printing buffer (8) to increase the length of the ribbon from the coating device (3) to the print head (6) and simultaneously driving the post-printing buffer (7) to decrease the length of the ribbon from the print head (6) to the coating device (3); A thermal transfer printing device (1) according to any one of claims 1 to 3.

5. The printing apparatus further includes a printing roller (21) that holds and transports the substrate (2) and the ribbon (5) along the printing zone, and the printing roller (21) is configured to: a printing arrangement allowing printing in which the ribbon (5) is supported by the printing roller via the substrate (2); a detached configuration in which the ribbon (5) has detached from the substrate (2); movable between two configurations; A thermal transfer printing device (1) according to claim 4.

6. a speed sensor for measuring the speed of the ribbon in the print zone; and a second controller (COMP) configured to control the print rollers (21) to automatically switch the configuration of the drive rollers when the measured speed of the ribbon in the print zone is zero. A thermal transfer printing device (1) according to claim 5.

7. the second controller (COMP) is configured to automatically drive the print roller (21) to transport the substrate (2) at the same speed as the speed of the ribbon in the print zone in the printing configuration; A thermal transfer printing device (1) according to claim 6.

8. the first controller (CALC) is configured to control the movement of the first and second moving rollers (81, 83) independently from controlling the movement of the third and fourth moving rollers (71, 73); A thermal transfer printing device (1) according to any one of claims 4 to 7.

9. The elastic modulus of the endless ribbon is less than 3 GPa; A thermal transfer printing device (1) according to any one of claims 1 to 8.

10. the first controller (CALC) is configured to control the rotation of the drive roller (11) and to control the first speed of the ribbon (5) in the coating zone; A thermal transfer printing device (1) according to claim 4.

11. - driving the moving rollers (81, 83) of the pre-printing buffer (8) to shorten the length of the ribbon from the coating device (3) to the print head (6) and simultaneously driving the moving rollers (71, 73) of the post-printing buffer (7) to lengthen the length of the ribbon from the print head (6) to the coating device (3), or by driving the moving rollers (81, 83) of the pre-printing buffer (8) to increase the length of the ribbon from the coating device (3) to the print head (6) and simultaneously driving the moving rollers (71, 73) of the post-printing buffer (7) to decrease the length of the ribbon (5) from the print head (6) to the coating device (3), - driving the ribbon (5) in the coating zone at a first predetermined speed while Driving the ribbon (5) in the print zone at a second speed different from the predetermined first speed; A method for printing a substrate with a thermal transfer printing apparatus according to any one of claims 1 to 10.

12. The thermal transfer printing device depends from claim 5, The method further comprises: - driving the ribbon (5) in the coating zone at a first predetermined speed while - driving the ribbon (5) in the print zone at a second speed less than the predetermined first speed; - by moving the printing roller (21) from the take-off configuration to the printing configuration while the second speed is less than the predetermined first speed, including printing, The method of claim 11.

13. driving the moving rollers (81, 83) of the pre-printing buffer (8) to shorten the length of the ribbon from the coating device (3) to the print head (6), and simultaneously driving the moving rollers (71, 73) of the post-printing buffer (7) to lengthen the length of the ribbon from the print head (6) to the coating device (3), thereby driving the speed of the ribbon in the print zone at a speed greater than the speed of the ribbon in the coating zone. further comprising the step of operating printing. The method of claim 12.

14. while driving the ribbon in the coating zone at a first speed; driving the moving rollers (83, 81) of the pre-printing buffer (8) to shorten the length of the ribbon from the coating device (3) to the print head (6) and simultaneously driving the moving rollers (71, 73) of the post-printing buffer (7) to lengthen the length of the ribbon from the print head (6) to the coating device (3), thereby driving the speed of the ribbon in the print zone at a second speed that is smaller than the first speed; - by moving said printing roller (21) into a disengaged configuration, further comprising releasing the printing.

14. The method according to claim 12 or 13.

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