JPH0569564A - Thermal transfer recording apparatus - Google Patents

Abstract

PURPOSE:To reproduce an image of high quality on image receiving paper while enhancing transfer efficiency by preventing the escape of heat from an ink film. CONSTITUTION:The irradiation position P of an ink film 18 with laser beam is set to a position separated from the nip part grasping the ink film 18 and image receiving paper 25 of a printing head 14 and a platen 13 and providing a gap Y between the ink film 18 and the image receiving paper 25. The light pervious recessed part 31 opened to the feed guide surface guiding the feed of the ink film 18 is formed to printing head 14. Both surfaces of the ink film 18 do not come into contact with both of the printing head 14 and the image receiving paper 25 when the ink film 18 is irradiated with laser beam and transfer is performed in such a state that the ink film 18 floats in the air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording apparatus in which an ink film and an image receiving paper are conveyed between a platen and a print head, and the ink film is irradiated with laser light to transfer the ink to the image receiving paper. ..

[0002]

2. Description of the Related Art Funk films used in a thermal transfer recording apparatus are a fusion type film in which ink of an ink film is heated and melted by a print head to adhere to an image receiving paper, and an ink of the ink film is sublimated by a print head to receive an image. There is a sublimation type film that is adhered to paper. As a sublimation type ink film, there is an ink film of a type in which the ink is sublimated by irradiating it with a laser beam (Japanese Patent Laid-Open No. 2-2).
No. 02488). In the ink film disclosed in this publication, a spacer beam is contained in either one of the ink films in order to prevent the ink film and the image receiving paper from sticking to each other.

[0003]

In a conventional thermal transfer recording apparatus using a thermal sublimation type ink film, a large pressure is applied to the image receiving paper and the ink film by the print head and the platen with respect to the image receiving paper and the ink film. ing. However, in a conventional thermal transfer recording apparatus using a sublimation type ink film, even if a type of ink film in which a laser beam is used to sublime ink is used, the surface of the image receiving paper is Since there are irregularities of about 2 μm, a white spot phenomenon called a void may occur. This void occurs because the ink in the dye layer is efficiently dyed on the convex portion of the image receiving paper, but the gap between the ink film and the ink film in the concave portion causes the dye to be larger than the convex portion. It is considered that this is because the transfer efficiency of is low. Further, since the dye layer of the ink film contains a binder other than the dye, these may be transferred to the recording paper as impurities, which causes image unevenness. Therefore, in a thermal transfer recording apparatus that mainly uses a sublimation type ink film, it is possible to prevent the occurrence of the voids and prevent the occurrence of transfer unevenness due to the transfer of impurities, thereby providing a high quality image on the image receiving paper. Reproducibility has become a technical problem to be solved today.

Further, if the light energy of the laser beam applied to the ink film for sublimating the ink can be reduced, the transfer efficiency can be improved accordingly. Therefore, in order to improve the transfer efficiency, the inventors have variously studied. Researched. As a result of research, in the past, the ink film was conveyed along the conveyance guide surface of the print head while being in contact with it, so the thermal energy generated by the photothermal conversion of the ink film irradiated and absorbed by the print head was absorbed. Has been found to have been.
Conventionally, it has been necessary to irradiate laser light with an intensity that includes excess energy absorbed. Therefore,
An object of the present invention is to improve the thermal transfer efficiency so that a high quality image can be formed on an image receiving paper with less light energy.

[0005]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides an ink by irradiating a laser beam onto the ink film while conveying the ink film and the image receiving paper while sandwiching them by a print head and a platen. In a thermal transfer recording device for thermally transferring to the image receiving paper, at a position having a gap between the ink film and the image receiving paper, away from the nip portion that holds the ink film and the image receiving paper by the print head and the platen, An irradiation position of the laser beam with respect to the ink film is set, and a translucent concave portion formed on the print head and opening on a conveyance guide surface for guiding the conveyance of the ink film is formed on the print head in correspondence with the irradiation position. The ink film when the ink film is irradiated with laser light. On both sides of Irumu it does not contact either of the image-receiving sheet and the print head, a thermal transfer recording apparatus, wherein the ink film is to perform the transfer in a state of floating in the air.

[0006]

The image receiving paper is nipped and conveyed by the nip formed by the platen and the print head. Since the irradiation position of the laser beam provided on the print head is provided at a position displaced from the nip portion, a gap is formed between the ink film and the image receiving paper at the irradiation position, and the ink film is formed on the image receiving paper. The image is formed in a non-contact state with. Further, at the position where the ink film is irradiated with the laser beam, the ink film is not in contact with the print head either, and the thermal energy photothermally converted by the ink film is not transferred from the ink film to the outside and a small amount of heat is generated. The energy efficiently transfers the ink to the image receiving paper.

[0007]

The present invention will now be described in detail based on the illustrated embodiments of the present invention. 1 to 3 are views showing a thermal transfer recording apparatus according to an embodiment of the present invention. As shown in FIG. 2, two support plates 11 and 12 arranged at a predetermined distance from each other are provided. The platen roller 13 is rotatably attached via a bearing (not shown). The platen roller 13 is driven by a motor (not shown), and as shown in FIG.
a and a rubber material layer 13b provided on the outer periphery thereof,
The center of rotation is indicated by O. The thickness of the rubber layer 13b is about 1 mm, and a rubber material having a hardness of 60 degrees or more according to the Asker standard is used so that the platen roller 13 has a high roundness. A print head 14 made of a glass plate is arranged adjacent to the platen roller 13, and in the illustrated case, the print head 14 is located above the platen roller 13.

On the lower surface of the print head 14, that is, the surface facing the platen roller 13, an ink film 18 to be fed from the supply roll 16 and to be wound up by the winding roll 17 is guided and moved. The ink film 18 is a pinch roll 21 made of rubber.
And a capstan roller 22 that presses the ink film 18 through the ink film 18, and moves in the direction indicated by arrow A in FIG. These rollers 21, 22 are located between the take-up roll 17 and the print head 14. In addition, the print head 14 and the supply roll 16
A metal tension roller 23 and a rubber tension roller 24 that presses the tension roller 23 against the metal tension roller 23 are provided between the roller 23 and the roller 23.
A slip clutch (not shown) is built in the 24, and a braking force for applying tension to the ink film 18 is applied to the ink film 18.

The image receiving paper 25 is guided to the platen roller 13 by contacting a substantially semicircular portion facing the print head 14, and the image receiving paper 25 is synchronized with the movement of the ink film 18 by the rotation of the platen roller 13. It is designed to be transported. Rotation center O of platen roller 13
On the other hand, the two paper pressing rollers 26 and 27 are pressed against the platen roller 13 via the image receiving paper, that is, the image forming paper 25, with a phase of approximately 180 °. The direction of conveyance of the image receiving paper 25 accompanying the rotation of the platen roller 13 is shown by arrow B.

The lower surface of the print head 14, that is, the transport guide surface that faces the platen roller 13 and guides the transport of the ink film 18 is, as shown in the figure, the platen roller 1.
It is convex toward 3 and is slightly curved. Thereby, when tension is applied to the ink film 18,
Wrinkles do not occur, and the ink film 18 adheres well to the conveyance guide surface of the print head. Platen roller 1
When the print head 3 and the print head 14 are brought into contact with each other as shown in FIG. 1, a nip portion N is formed. The width of the nip portion N is set to about 1 mm. The ink film 18 is conveyed while being guided by the conveying guide surface of the print head 14, and the image receiving paper 25 is conveyed while being guided by the arcuate facing surface, so that they are first conveyed toward the nip portion N along with the conveyance. , And contact at the nip portion N, they pass through this portion and separate from each other.

As shown in FIG. 1, a transfer portion, that is, an irradiation position P is provided at a position displaced by a stroke X on the downstream side in the conveyance direction of the ink film 18 and the image receiving paper 25 from the center of the nip portion N. There is. This irradiation position P is
The laser beam L having a wavelength of 810 nm is set by the optical system 28 so as to be focused on the photothermal conversion layer of the ink film 18. The laser light source is a high-power semiconductor laser, for example, SLD304X manufactured by Sony Corporation.
Use T. In order to reduce the reflection of the laser beam L having the above wavelength on the surface of the glass print head 14, an antireflection treatment is applied to the surface of the print head 14 by applying a metal vapor deposition film or the like. On the other hand, the platen roller 13 is preferably raised to a predetermined temperature in order to increase the dye receiving efficiency of the image receiving paper, that is, the image density.

Thus, the irradiation position P of the laser beam is
Is provided at a position deviated from the center of the nip portion N, an air gap having a dimension Y is formed between the ink film 18 and the image receiving paper 25 at this position, and the ink of the ink film 18 is formed on the image receiving paper 25. Are transferred in a non-contact state. The value of the air gap Y is adjusted by the distance X between the rotation center O of the platen roller 13 and the optical axis of the laser beam L, that is, the irradiation position P. In the illustrated case, this value Y can be adjusted within the range of 0 <Y <200 μm. To form a high quality image on the image receiving paper 25, this value is set to 5 <Y <50 μm.
It is preferable to set in the range of m.

As shown in FIG. 1, the printhead 1
A light-transmitting concave portion 31 is formed on the sheet 4 in correspondence with the irradiation position P and opens on the conveyance guide surface. As shown in FIGS. 1 and 2, the recess 31 is formed by providing a groove over the entire length of the print head 14 in parallel with the rotation center O of the platen 13. Therefore, when the ink film 18 is irradiated with the laser beam, the front and back surfaces of the ink film 18 do not come into contact with either the print head 14 or the image receiving paper 25, and the ink film 1
The transfer is carried out with 8 floating in the air. This allows
The heat energy that is photothermally converted in the ink film 18 having a small heat capacity is not absorbed by the glass print head 14 having a large heat capacity that maintains a room temperature,
It is consumed as energy for sublimating ink efficiently. As described above, forming the groove or the concave portion 31 not only improves thermal efficiency but also contributes to increase in printing speed, and the ink film 18 is not brought into frictional contact with the laser light transmitting portion. It also serves to prevent a decrease in the amount of transmitted light due to scratches and adhesion of impurities.

At the edge of the opening of the translucent recess 31,
As shown in FIG. 1, an arcuate R portion 32 is formed. The R portion 32 prevents the back surface of the ink film 18 from being scratched and prevents impurities attached to the ink film 18 from accumulating in the recess 31.

FIG. 4 is a view showing the constitution of the ink film 18 and the image receiving paper 25. The ink film 18 is, for example,
On the base film 18a formed of polyethylene terephthalate or the like and having a small absorption at the wavelength of the laser beam L, a photothermal conversion layer 18b having a large absorption formed of, for example, carbon and a color in which a dye is dispersed in a polymer binder. The agent layer 18c is applied. On the other hand, the image receiving paper 25
An image receiving layer 25b that receives a dye such as polycarbonate or polyurethane is coated on a substrate 25a such as polyester or condenser paper.

When the laser light L is focused on the photothermal conversion layer 18b of the ink film 18, the photothermal conversion agent generates heat,
The heat is transmitted to the color material layer 18c. When the sublimable dye is excited by heat in the colorant layer, what was previously in the polymer binder as a solid vaporizes and jumps out. At that time,
When the image receiving layer 25b is located very close to the image receiving layer 25, the sublimable dye that has jumped out is trapped in the image receiving agent and, as a result, the image receiving layer 25
It is dyed to b. After the image receiving layer 25b is dyed, it is preferably cooled once to the room temperature level. This is because the bond between the dye and the image receiving agent is strengthened so that the dye does not resublime even if it receives heat again. This is especially true
In a color printer using 3 to 4 colors, the image receiving paper 25 is exposed to heat again when dyeing the next color, which is important for maintaining color balance.

Next, referring to FIG. 2, the platen roller 13
A procedure for adjusting the distance X between the center O and the optical axis and the width Y of the air gap will be described. As shown in the figure, the platen roller 13 and the print head 14 are pressed against each other, and the rubber material 13b of the platen roller 13 is deformed by the pressure to form a nip portion N having a certain width. However, in FIG. 2, the ink film 18 and the image receiving paper 25 conveyed in a state of being sandwiched between the platen roller 13 and the print head 14 are not shown. Therefore, in FIG. 2, it is assumed that the image receiving paper 25 is in a wound state. Two support plates 1
Photosensors H for detecting the laser beam L are attached to 1 and 12, and the laser beam L is scanned at the position of this sensor H in the direction of the main scanning line S. The mounting position of the sensor H is adjusted to be a distance Z with respect to the rotation center O of the platen roller 13. The width Y of the air gap is determined by the platen roller 1
Although it is determined by the distance Z between the rotation center O of 3 and the main scanning line S, when the main scanning line S is located in the nip portion N,
Since the width Y of the air gap becomes O, the value of Z is always larger than 1/2 of the width of the nip portion N.

The main scanning line position is adjusted by adjusting the optical system, and the main scanning line S of the laser beam L scanned at that time passes through the centers of the left and right photosensors H. The photosensor H is set so that the output voltage becomes maximum when the laser beam L crosses the center of the element by means such as providing a slit on the light receiving element. In this way, if both the left and right photosensors H are adjusted so as to have the maximum output, the positional relationship between the photosensor H and the center O of the platen roller 13 has already been adjusted, so that the optimum air gap width is obtained. The laser beam L scans the position of Y.

The relationship between the values X and Y described above will be described with reference to FIG. 3. Let R be the radius of the platen roller 13 including the image receiving paper 25 when the image receiving paper 25 is wound, and the nip portion N. Reference line M orthogonal to the line connecting the center O
And the irradiation position P is a, and the distance to the intersection of the reference line M and the surface of the image receiving paper 25 is b, the value of Y is Y = ab. Then, since a = R, b
The value of is calculated by the following formula. b = (R ² −X ² ) ^{1/2 In} this way, the value of the air gap Y is obtained, but in reality, the size is obtained by subtracting the dent of the rubber layer 13b of the platen roller 13.

FIG. 5 and FIG. 6 are views showing a thermal transfer recording apparatus according to another embodiment of the present invention, and the members common to the members in the above embodiment are designated by the same reference numerals. In the case shown in FIG. 5, the translucent recess 31 is formed by forming a step portion on the downstream side of the ink film 18 with respect to the irradiation position P of the print head 14. Forming the step in this way is easier to process the recess 31 than forming the groove as shown in FIG.

In the print head 14 shown in FIG. 6, the translucent recess 31 is formed by forming a groove in which circular arc surfaces including the R portion 32 are connected. As described above, as the shape of the concave portion 31, as long as the portion of the ink film 18 to which the laser light L is irradiated does not contact not only the image receiving paper 25 but also the conveyance guide surface of the print head 14, various shapes are possible. It is possible to set the shape. Further, as the shape of the print head 14, the radius of curvature thereof may be reduced to such an extent that the transport guide surface has a semicircular shape, or the transport guide surface may be flat.

As described above, since the transfer portion P, that is, the portion to which the laser beam L is irradiated is set at the position deviated from the nip portion N, the ink film 18 guided to the print head 14 and the image receiving guided to the platen 13 are set. An image is formed at a position where the paper 25 is separated from each other. As a result, the color material layer 18c of the ink film 18 and the image receiving paper 25
The dye is transferred without being in contact with the surface of the dye. Therefore, impurities other than the dye are not transferred to the image receiving paper, the occurrence of image unevenness is prevented, and a high-quality beautiful image is reproduced. Also, the image receiving paper 25
As a result, the unevenness size of the surface of the is relatively smaller than the size of the air gap Y, so that it is not affected by the unevenness, and the voids, that is, the white spots, which are generated in the contact type, as in the past, are eliminated. It has become possible to reproduce high-quality images from the viewpoint of eliminating the phenomenon.

Further, from the ink film 18 to the image receiving paper 25
Not only does heat not escape, but since the translucent recess 31 is formed in the print head 14, the ink film 18 is suspended in the air, so that heat energy does not escape to the outside of the ink film, and the thermal transfer efficiency of the dye is improved. Has improved. In addition, it has become possible to reduce the printing speed as the thermal transfer efficiency is improved. Then, in the position P of the ink film 18 where the laser light is irradiated,
Since the preton head 14 does not contact, it is possible to maintain a clean state as an optical member for a long period of time, and it is possible to suppress the secular change of the transmitted light amount as much as possible. Since the R portion 32 is formed at the opening edge portion of the concave portion 31, it is possible to prevent the coating material and impurities on the back surface of the ink film 18 from being scraped off and accumulated in the concave portion 31, and to reduce the amount of transmitted light. Not only can this be prevented, but the maintenance cycle for cleaning the print head 14 can be lengthened.

Since the ink film 18 contains a heating element, heat can be efficiently transferred to the sublimation dye without applying a large pressure between the print head and the platen, resulting in a load on the drive system. Has become smaller, making it possible to make the device lighter and more compact. Also,
Since the base thickness of the ink film is not related to the thermal efficiency unlike the case of using the thermal head, the ink film can be made thicker, which facilitates the manufacturing of the device and the handling of the ink film in the device.

Instead of the platen roller 13 of the above embodiment, it is possible to use a platen having a flat opposing surface. Further, in the illustrated embodiment, the nip portion N
On the other hand, although the irradiation position P is provided on the downstream side in the transport direction of the image receiving paper 25 and the ink film 18, the irradiation position P may be provided on the upstream side in the transport direction. Print head 1 corresponding to the irradiation position
In FIG. 4, a concave portion 31 composed of a groove, a step or the like is formed on the upstream side of the nip portion N.

[0026]

As described above, according to the present invention, the print head and the like are not in contact with both sides of the ink film, and the ink is transferred to the image receiving paper while the ink film is suspended in the air. Therefore, the heat energy does not escape to the outside of the ink film, and the thermal transfer efficiency of the ink is greatly improved. Moreover, since impurities other than the dye are not transferred to the image receiving paper and the generation of voids is prevented, it is possible to reproduce a high quality image.

[Brief description of drawings]

FIG. 1 is a sectional view showing a thermal transfer recording apparatus according to an embodiment of the present invention,

FIG. 2 is a plan view of FIG. 1 with an ink film and the like omitted.

FIG. 3 is an explanatory diagram showing the relationship between the position of the transfer portion with respect to the center of the nip portion and the gap in the thermal transfer recording apparatus shown in FIGS. 1 and 2.

FIG. 4 is a sectional view showing a structure of an ink film and an image receiving paper,

FIG. 5 is a sectional view showing a thermal transfer recording apparatus according to another embodiment of the present invention,

FIG. 6 is a sectional view showing a thermal transfer recording apparatus according to still another embodiment of the present invention.

[Explanation of symbols]

13 ... Platen roller, 14 ... Print head, 18 ...
Ink film, 25 ... Image receiving paper, 31 ... Translucent recess, 32
... R part, N ... Nip part, P ... Irradiation position.

Claims (2)

[Claims] 1. A thermal transfer recording apparatus for thermally transferring ink to an image receiving paper by irradiating the ink film with laser light while transporting the ink film and the image receiving paper while sandwiched between the print head and a platen. The irradiation position of the laser beam with respect to the ink film is set at a position apart from the nip portion that holds the ink film and the image receiving paper by the platen and having a gap between the ink film and the image receiving paper, and the printing is performed. A translucent concave portion formed on the head and opening on a conveyance guide surface for guiding the conveyance of the ink film is formed in the print head so as to correspond to the irradiation position, and the ink film when the ink film is irradiated with laser light. Both sides of the print head and the image receiving paper A thermal transfer recording apparatus, characterized in that the transfer is carried out in a state where the ink film is suspended in the air without contacting any of them. 2. The thermal transfer recording apparatus according to claim 1, wherein an edge portion of an opening of the light transmissive recess formed in the print head is formed in an arc shape.