JPH0572438U - Thermal transfer image recording device - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the image quality of a thermal transfer type image recording apparatus in which ink of a donor sheet is melted and transferred to an image receiving sheet. A donor sheet D that rotates together with the rotating drum 2 at a laser irradiation position P1 from the laser head 6 to the donor sheet D or a predetermined position P2 in front of the irradiation position P1 with respect to the rotation direction F of the rotating drum 2. The compressed gas is blown onto the laser irradiated portion. [Effect] The ink of the donor sheet can be transferred uniformly and at a high transfer rate to the image receiving sheet by bringing the portion of the donor sheet where the heat-meltable ink is melted into contact with the image receiving sheet by air pressure.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention is mainly a thermal transfer image recording device used in a system called a direct digital color proofing system (hereinafter referred to as DDCP) that directly receives image data from an image processing device and performs color calibration. Regarding

[0002]

[Prior Art]

 Due to the advantages that the above-mentioned DDCP does not stain the hands of workers and does not require a special environment called a calibration room for performing calibration, the demand for proof printing has recently increased. There is. In general, the DDCP thermally transfers the ink applied to the donor sheet to the image-receiving sheet that serves as a print medium for each color component by sublimating or melting the ink applied to the donor sheet based on the image data acquired by the image processing apparatus. The ink thermally transferred to the image receiving sheet is sequentially retransferred to the printing paper to obtain a proof print, that is, a recorded image.

By the way, as a method of transferring the ink of the donor sheet to the image-receiving sheet in the above, the image-receiving sheet and the donor sheet are wound around the rotating drum in a superposition state, and the ink applied to the donor sheet is melted or melted by a semiconductor laser. There is a method of recording an image on the image-receiving sheet by sublimating and then peeling off the donor sheet from the image-receiving sheet.

When the ink applied to the donor sheet is melted or sublimated and transferred to the image-receiving sheet in this manner, at least the donor sheet irradiated with the semiconductor laser is immediately exposed to the image-receiving. Must be kept in close contact with the seat. In particular, in the melting type thermal transfer in which the ink of the donor sheet is melted and then transferred to the image-receiving sheet, in order to transfer the melted ink to the image-receiving sheet at a high transfer rate, at least the time of ink transfer is required. It is necessary to bring the donor sheet and the image-receiving sheet into close contact with each other with a strong adhesive force.

Therefore, in the conventional thermal transfer type image recording apparatus in the DDCP, as shown in FIG. 8, many suction small holes 101 are formed on the outer periphery of the drum 100 around which the image receiving sheet R and the donor sheet D are wound. At the same time, a suction port 103 is formed on the rotary shaft 102 of the drum 100, and air in the drum 100 can be sucked through the suction port 103 by a suction device (not shown).

Then, the image receiving sheet R and the donor sheet D are generally wound around the drum 100 as described below. That is, with the air in the drum 100 being sucked through the suction port 103, first, the image receiving sheet R is wound around the drum 100 at a position corresponding to the small hole 101 punched portion, and A donor sheet D is further wound around the image receiving sheet R, and a cover sheet C that is larger than the image receiving sheet R and the donor sheet D and completely closes the small holes 101 is wound around the donor sheet D. As a result, the cover sheet C is brought into close contact with the outer peripheral surface of the drum 100, and the donor sheet D pressed by the cover sheet C is brought into close contact with the image receiving sheet R.

[0007]

[Problems to be solved by the device]

 However, the means for bringing the donor sheet D and the image receiving sheet R into close contact with each other only by sucking the air in the drum 100 as shown in FIG. 8 has the following disadvantages.

That is, in FIG. 8, the adhesion force between the donor sheet D and the image receiving sheet R obtained by sucking the air in the drum 100 is 1 kg / kg even if the inside of the drum 100 can be evacuated. The limit is cm ² , and the reality is that only an adhesion of about 0.1 Kg / cm ² is actually obtained. However, in the above-mentioned fusion type thermal transfer, it is impossible to perform transfer at a high transfer rate when the adhesive force is about 0.1 Kg / cm ² . That is, in the conventional apparatus, the adhesion force required for the sublimation thermal transfer can be obtained as the adhesion force between the donor sheet and the image receiving sheet, but it is difficult to obtain the sufficient adhesion force required for the fusion thermal transfer. Met.

Further, as shown in FIG. 8, when the cover sheet C is brought into close contact with the outer periphery of the drum 100, the air that has entered between the cover sheet C and the donor sheet D loses its escape route, and FIG. As shown in (3), there is a possibility that air traps E may partially occur between the cover sheet C and the donor sheet D. If such an air pocket E is generated, the adhesion between the donor sheet D and the image receiving sheet R at the location corresponding to the air pocket E may be reduced, and the transfer may be partially uneven.

In order to avoid the occurrence of the air pool E as shown in FIG. 9, as shown in FIG. 10, the donor sheet D is used as the image receiving sheet R and the small hole 101 formed in the drum 100 is provided. It is conceivable that the donor sheet D and the image receiving sheet R can be brought into close contact with each other without using the cover sheet C by completely closing the donor sheet D. However, in this case, it becomes more difficult to maintain a high degree of vacuum inside the drum 100 as compared with the case where the cover sheet C is used. That is, since the donor sheet D is usually an extremely thin film and has a weak strain, the donor sheet D adheres to the drum 100 only near the small holes 101 due to the suction of air, and the donor sheet D and the image-receiving sheet. Overall adhesion with R cannot be obtained. For this reason, there arises a problem that the average adhesive force between the donor sheet D and the image receiving sheet R is further reduced.

The present invention has been made in view of the above circumstances, and the donor sheet is melted by bringing the donor sheet into close contact with the image-receiving sheet wound around a rotating drum and irradiating with a laser. In a thermal transfer type image recording apparatus that transfers the heat-meltable ink of (1) to the image receiving sheet, it is possible to bring the above-mentioned image receiving sheet and donor sheet into close contact with each other with the adhesive force required for transfer, at least immediately after laser irradiation. It is an object of the present invention to provide a thermal transfer type image recording device.

[0012]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the thermal transfer image recording apparatus of the present invention has a laser irradiation position of the donor sheet that rotates with the drum in front of the irradiation position of the laser on the donor sheet or the irradiation position with respect to the rotation direction of the drum. Compressed gas is blown onto the illuminated area.

[0013]

[Action]

 In the thermal transfer type image recording apparatus of the present invention, the donor sheet, which is subjected to the pressure due to the compressed gas blowing in front of the irradiation position of the laser on the donor sheet or the irradiation position with respect to the rotation direction of the drum, is more affected than before. Also adheres to the image-receiving sheet with great adhesion.

[0014]

【Example】

 The thermal transfer image recording apparatus shown in FIGS. 1 to 7 includes a frame 1, a rotary drum 2, a drum driving device 3, an air suction device 4, a traveling device 5, a laser head 6, a compressed air blowing device 7, and a sheet feeding device. 8 and a sheet peeling device 9.

As shown in FIGS. 1 and 2, the frame 1 includes a base 11 and a pair of arms 12 and 13 extending obliquely upward and rearward at both left and right ends of the base 11. As shown in FIG. 3, a pair of rotation shafts 14 and 15 arranged on the same axis are fixed to the arms 12 and 13, respectively. One of the rotary shafts 14, 15 has a pipe shape with both ends open. The base 11 is provided with a pair of support pieces 16 and 17 facing each other at both left and right ends thereof. Further, the base 11 is provided with a pair of guide grooves 18 extending in the left-right direction to guide a traveling block 52 described later.

As shown in FIG. 3, the rotary drum 2 is rotatably supported by the rotary shafts 14 and 15 at the respective end faces. The sliding portion between the rotary drum 2 and the rotary shafts 14 and 15 is hermetically sealed to prevent air leakage. The rotary drum 2 is formed with a sleeve 21 that is concentric with the rotary shaft 15 and projects outward at an end surface that axially supports the rotary shaft 15. A pulley 22 is fixed to the sleeve 21. ing. Further, on the outer peripheral wall of the rotary drum 2, as shown in FIG. 4, a plurality of small suction holes 23 are formed in a predetermined area A in the circumferential direction. The size of the predetermined area A is determined according to the lengths of the image-receiving sheet R and the donor sheet D wound around the rotary drum 2.

The drum driving device 3 includes a reversible motor 31 as a rotation driving source of the rotary drum 2. A pulley 32 is fixed to the rotary shaft of the reversible motor 31, and a belt 33 is wound around the pulley 32 and the pulley 22 mounted on the rotary drum 2. Therefore, by switching the rotation direction of the reversible motor 31, the rotary drum 2 can be rotated in any direction. The reversible motor 31 has a predetermined rotation speed (for example, 60 r.p.m.) in a direction (the arrow F direction in FIG. 2) for moving the rotating drum 2 upward at a portion facing the laser head 6 at the time of thermal transfer described later. pm) can be rotated.

The air suction device 4 includes a blower duct 41, one end of which is connected to a pipe-shaped rotary shaft 14 that pivotally supports the rotary drum 2. The other end of the blower duct 41 is connected to an air suction source such as an air pump (not shown). That is, by operating the air suction source, the air in the rotary drum 2 can be sucked through the blower duct 41.

As shown in FIG. 2, the traveling device 5 includes a rod 51, a traveling block 52, and a step motor 53.

The rod 51 is externally threaded over substantially the entire length except for both ends. Both ends of the rod 51 are axially immovably and rotatably supported by the support pieces 16 and 17 of the frame 1 in a state parallel to the rotation axis of the rotary drum 2. A pulley 511 is attached to one end of the rod 51.

The traveling block 52 is fitted in the guide groove 18 formed in the base 11 so as to be slidable in the left-right direction. Further, the traveling block 52 is provided with a rod through hole 521 penetrating in the left-right direction, and a female screw (not shown) screwed to the male screw of the rod 51 is screwed on the inner peripheral surface of the rod through hole 521. Has been done.

The stepping motor 53 is mounted on the base 11 in a state in which the drive rotation shaft is parallel to the rod 51. A pulley 531 is attached to the drive rotating shaft of the stepping motor 53, and a belt 532 is wound around the pulley 531 and a pulley 511 attached to the end of the rod 51.

In the traveling device 5 configured as described above, the rod 51 is rotated by operating the stepping motor 53, and the rotation of the rod 51 causes the traveling block 52 to move in the axial direction of the rod 51. That is, the traveling block 52 can be moved in any of left and right directions by an arbitrary amount by controlling the rotation direction and rotation amount of the stepping motor 53.

The laser head 6 is mounted on the traveling block 53 of the traveling device 5. The laser head 6 has a plurality of infrared laser diodes. For example, when 32 infrared laser diodes each having a diameter of 6.35 μm are laterally arranged, the laser head 6 has an irradiation width of about 0.2 mm as a whole. As shown in FIG. 5, the infrared laser L oscillated from the laser head 6 forms a horizontal line on the donor sheet D wound around the rotating drum 2 and passing through the center of the rotating drum 2 in a procedure described later. Focus on the intersection. That is, the position where this focus is formed is the irradiation position P1 of the infrared laser on the donor sheet D. A halftone dot signal obtained by converting image data obtained by a known image processing device such as a color scanner is input to the laser head 6, and each infrared laser diode is turned on / off based on the halftone dot signal. , Oscillates the laser when turned on. The image data may be image data of an original image read by the scanning reading unit of the image processing apparatus, or may be image data after image processing obtained by gradation conversion of the image data of the original image. .. For simplicity, the signal lines connected to the laser head 6 are omitted in the figure.

As shown in FIGS. 1 and 2, the compressed air blowing device 7 includes a compressor 71 that is a compressed air source and an air blowing nozzle 72 that blows out the compressed air sent from the compressor 71. .. The air blowing nozzle 72 is formed of a metal pipe, and is fixed to the laser head 6 via a fixture 61. A valve 73 is connected to the compressor 71, while a pressure meter 74 is connected to the air blowing nozzle 72. The valve 73 and the pressure meter 74 are connected by a flexible tube 75. In FIG. 1, reference numeral 75A indicates a region in which the flexible tube 75 is omitted. As shown in FIG. 5, the air blowing nozzle 72 blows compressed air to a predetermined position P2 above the irradiation position P1 of the laser emitted from the laser head 6.

The predetermined position P2 is preferably a position where the irradiated portion of the donor sheet D irradiated with the infrared laser at the irradiation position P1 reaches when the ink in the irradiated portion is melted. That is, when it takes 1 msec for the ink of the donor sheet D to be melted after being irradiated with the laser, the position where the donor sheet D at the irradiation position P1 reaches after 1 msec due to the rotation of the rotary drum 2 is set to the fixed position P2. And For example, the outer circumference of the rotary drum 2 is 1000 mm, and as described above, the rotary drum 2 rotates clockwise by 60 rpm in FIG. p. When rotating at m, the predetermined position P2 is set 1 mm above the irradiation position P1 so that the irradiated portion of the donor sheet D, which has been irradiated with the laser at the irradiation position P1, has a predetermined position 1 msec after irradiation. The position P2 can be reached.

The air blowing nozzle 72 is provided so that air can be blown to the predetermined position P2 at a predetermined pressure. According to the experiment, the inner diameter of the air blowing nozzle 72 is 0.7 mm, the air pressure of the compressed air given from the compressor 71 is 6 Kg / cm ² , the tangent line SL passing through the predetermined position P2 and the air blowing nozzle 72. When the angle θ between the axes (see FIG. 5) is set to 60 degrees, and the distance k between the air outlet 72a and the tangent line SL is set to 0.5 to 1.0 mm, the predetermined position P2 is 2. An air pressure of ² Kg / cm ² could be obtained. The predetermined air pressure at the predetermined position P2 can be increased as the angle θ between the tangent line SL and the axis of the air blowing nozzle 72 approaches 90 degrees. In the above, when only the angle θ was changed to 90 degrees without changing other conditions, the air pressure at the predetermined position P2 was 2.6 Kg / cm ² .

If pressure can be applied to a certain area around the predetermined position P2 by adjusting the shape, angle, air pressure, etc. of the air blowing nozzle 72, this area However, at least the melting position may be covered.

As shown in FIG. 1, the sheet feeding device 8 includes a magazine 81 for storing the rolled donor sheet D and a magazine 82 for storing the rolled image-receiving sheet R as well. The donor sheet D and the image-receiving sheet R fed from these magazines 81 and 82 are the common feeding paths for the individual feeding paths 81A and 82A and the sheets D and R that are connected to these magazines 81 and 82. It is supplied to the upper part of the rotary drum 2 via 83. The feeding path 83 includes a pair of feeding rollers 84 to 86 driven by a pulse motor (not shown). A cutter device 87 for cutting the donor sheet D or the image-receiving sheet R passing through the feeding path 83 into a predetermined length is provided in an intermediate portion between the feeding roller 84 and the feeding roller 85. Further, corresponding to the end portion of the feeding path 83, that is, the sheet supply portion 88 for the rotating drum 2, a position where the donor sheet D wound around the rotating drum 2 comes into contact with and a position where the donor sheet D is separated from the donor sheet D. A pressure roller 89 is provided which can move between them.

The sheet peeling device 9 includes a first peeling groove 91, a second peeling groove 92 (see FIG. 2), and a peeling claw 93 (see FIG. 1). A plurality of first peeling grooves 91 are provided on the outer circumference of the rotating drum 2 along the axial direction of the rotating drum 2. Further, the second peeling groove 92 has the same shape as the first peeling groove 91, and the second peeling groove 91 has the same shape as the first peeling groove 91 with respect to the rotation direction (arrow F direction) of the rotary drum 2 during transfer. It is provided in the rear. The peeling claw 93 can be swung between a sheet peeling position shown by a solid line in FIG. 1 or 6 and a sheet non-peeling position shown by a two-dot chain line. As shown in FIG. 6, the sheet peeling position is a position where the tip of the peeling claw 93 is recessed into the first peeling groove 91 or the second peeling groove 92. Further, at the sheet non-peeling position, the tip of the peeling claw 93 does not sink into the first peeling groove 91 or the second peeling groove 92, and the peeling claw 93 and the rotary drum 2 are not separated from each other. This is a position where the image receiving sheet R and the donor sheet D wound around the rotary drum 2 can pass through the space.

In the thermal transfer type image recording apparatus configured as described above, the heat-meltable ink of the donor sheet D is transferred to the image receiving sheet R as follows.

First, the sheet feeding device 8 feeds the image-receiving sheet R stocked in the second magazine 82 to the rotary drum 2 side via the feeding paths 82 A and 83, and the cutter 87 feeds the image-receiving sheet R. The sheet R is cut into a predetermined length. Further, the air suction device 4 is activated to start sucking air in the rotary drum 2.

Next, as shown in FIG. 7A, the second peeling groove 92 of the rotary drum 2 and the leading end of the image receiving sheet R are made to correspond to the sheet feeding portion 88, and the pressure contact roller 89 is attached to the rotary drum. The surface of 2 is pressed. Then, from this state, the rotary drum 2 is rotated in the arrow F 2 direction, and the image receiving sheet R is supplied to the sheet supply section 88 by the sheet supply device 8 at the same speed as the rotational speed of the rotary drum 2. As a result, the image-receiving sheet R passes between the rotary drum 2 and the pressure roller 89 and follows the outer circumference of the rotary drum 2. The image-receiving sheet R along the outer periphery of the rotary drum 2 is held by the rotary drum 2 as shown in FIG. 7B by being sucked into the suction small holes 23 formed in the rotary drum 2. To be done.

Next, the sheet feeding device 8 feeds the donor sheets D stocked in the first magazine 81 to the rotary drum 2 side via the feeding paths 81 A and 83, and the donor 87 is fed by the cutter 87. The sheet D is cut into a predetermined length longer than the image receiving sheet R.

Next, as shown in FIG. 7C, the leading edge of the donor sheet D is made to correspond to the sheet feeding portion 88, and the rotary drum 2 is reversed to rotate the first sheet provided on the rotary drum 2. The peeling groove 91 is moved to a position corresponding to the sheet supply unit 88.

Next, the rotary drum 2 is rotated again in the arrow F direction, and the donor sheet D is supplied to the sheet supply unit 88 by the sheet supply device 8. As a result, the donor sheet D extends along the outer periphery of the rotary drum 2 from above the image receiving sheet R with its tip aligned with the first peeling groove 91, as shown in FIG. 7D. The donor sheet D is wound around the rotary drum 2 so as to completely cover the image receiving sheet R, and in this state, the peripheral portion that does not overlap with the image receiving sheet R is sucked into the suction small holes 23 and the image receiving sheet R is received. The overlapped portion of and adheres to the image-receiving sheet R.

The image receiving sheet R and the donor sheet D are wound around a predetermined position while being in close contact with each other on the rotary drum 2 as described above.

After the winding is completed as described above, the infrared laser oscillated based on the halftone dot signal from the laser head 6 is rotated while rotating the rotary drum 2 in the arrow F direction at a predetermined rotation speed. Irradiate on the donor sheet D. Further, the compressed air blowing device 7 is operated, and immediately after the infrared laser irradiation by the laser head 6, the compressed air is blown to the laser irradiated portion of the donor sheet D at the predetermined position P2. By this air blowing, the donor sheet D and the image-receiving sheet R are brought into close contact with each other at the predetermined position P2 with an extremely high adhesion force exceeding the adhesion force due to the suction force of the air suction device 4. Therefore, the heat-meltable ink of the donor sheet D melted by the irradiation of the infrared laser is transferred to the image-receiving sheet R at a high transfer rate.

In the above embodiment, the predetermined position P2, which is the air blowing position by the compressed air blowing device 7, is set to the position where the laser irradiation section passes 1 msec after the laser irradiation. Need only be in front of the laser irradiation position in the rotating direction of the rotary drum 2, and is not necessarily limited to the position of the embodiment. However, in general, the heat-meltable ink applied to the donor sheet D is melted 0 to 3 msec after laser irradiation, so the predetermined position P2 should also coincide with this melting, and laser irradiation is performed 0 to 3 msec after laser irradiation. It is preferable to set the position where the parts pass.

If the laser output is increased or the donor sheet D is preheated with warm air before reaching the laser irradiation position P1, the melting of the heat-meltable ink due to the laser irradiation is accelerated, It is expected that it will be necessary to bring the predetermined position P2 closer to the laser irradiation position P1. As described above, the predetermined position P2 is determined by the output of the laser diode forming the laser head 6, the presence or absence of preheating of the donor sheet D, or the melting speed of the ink depending on the nature of the heat-meltable ink itself applied to the donor sheet D. In consideration of the above, it is preferable to appropriately set so that the air is blown to the laser irradiation portion when the ink is melted.

Further, the pressure applied by the air blown from the air blowout nozzle 72 to the laser irradiation portion at the predetermined position P2 is the air pressure given by the compressor 71, the inner diameter of the air blowout nozzle 72 or the inclination angle of the air blowout nozzle 72. It can be changed by adjusting etc.

[0042]

[Effect of the device]

 As described above, according to the thermal transfer image recording apparatus of the present invention, the donor sheet can be brought into close contact with the image-receiving sheet by the air pressure when the heat-meltable ink of the donor sheet is melted after the laser irradiation. Therefore, it becomes possible to reliably transfer the melted ink to the image receiving sheet with a high transfer rate, and it is possible to obtain a uniform and clear high-quality image by the heat transfer using the heat-melting ink. It has the effect of becoming

[Brief description of drawings]

FIG. 1 is a side view of a thermal transfer image recording apparatus according to the present invention.

FIG. 2 is a perspective view of a main part of the thermal transfer type image recording apparatus of FIG.

FIG. 3 is a cross-sectional view of a main part of the thermal transfer image recording apparatus of FIG.

FIG. 4 is a sectional view of a rotary drum.

FIG. 5 is an enlarged explanatory diagram showing a relationship between an air outlet and a laser irradiation position.

FIG. 6 is a diagram illustrating a sheet peeling process.

FIG. 7 is an explanatory diagram showing a mounting process of an image receiving sheet and a donor sheet.

FIG. 8 is a cross-sectional view illustrating a conventional technique.

FIG. 9 is a diagram illustrating an air pocket.

FIG. 10 is a diagram illustrating another conventional technique.

[Explanation of symbols]

 2 rotary drum 6 laser head 7 compressed air blowing device 72 air blowing nozzle P1 laser irradiation position P2 predetermined position R image receiving sheet D donor sheet

Claims (1)

[Scope of utility model registration request] 1. A thermal transfer type image recording apparatus, wherein a donor sheet is brought into close contact with an image receiving sheet wound around a rotating drum, and the heat fusible ink of the donor sheet melted by irradiating a laser is transferred to the image receiving sheet. There is a laser irradiation position on the donor sheet or in front of the irradiation position with respect to the rotation direction of the drum, a compressed gas is blown to the laser irradiation portion of the donor sheet rotating with the drum. A thermal transfer type image recording device.