JPH1178138A - Color thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the margin of a color thermal recording sheet without degrading an image. SOLUTION: A fixing unit 36 for a yellow thermal coloring layer subjected to thermal recording at first is disposed above a pinch roller 28 and a color thermal recording sheet 16 is irradiated with UV-rays from the opposite sides. Carriage of the color thermal recording sheet 16 is stabilized by disposing a roller 30 pressing a capstan roller 27 with a uniform pressure while preventing flexure of the pinch roller 28 without interrupting irradiation of UV-rays from the yellow fixing unit 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color thermal printer of a reciprocating type, and more particularly to a color thermal printer for reducing the margin of a color thermal recording paper.

[0002]

2. Description of the Related Art On a support, at least three types of thermosensitive coloring layers, for example, a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer,
2. Description of the Related Art A color thermal printer that prints a full-color image using a color thermal recording paper in which yellow thermal coloring layers are sequentially formed is known. In this color thermal printer, when printing, the thermal head is pressed against the color thermosensitive recording paper, the yellow image is thermally recorded line by line on the yellow thermal coloring layer having the highest thermal sensitivity, and immediately thereafter, the yellow thermal coloring layer is irradiated with ultraviolet rays. To settle. Next, a magenta image is thermally recorded on the magenta thermosensitive coloring layer, and then fixed by irradiating ultraviolet rays. Finally, a cyan image is thermally recorded on the cyan thermosensitive coloring layer to obtain a full-color image.

[0003] Such thermal recording and fixing are performed while the color thermosensitive recording paper moves relative to the thermal head and the fixing device. One of the methods for moving the color thermosensitive recording paper is a reciprocating method. As shown in FIG. 8A, a color thermal printer using this reciprocating method includes a capstan roller 2 driven to rotate by a motor and a pinch roller 3 having a smaller diameter than the capstan roller 2. A roller pair 4 is used. The transport roller pair 4 nips the color thermal recording paper 5 and alternately transports the recording paper 5 in a forward direction from the paper supply side to the paper discharge side and a reverse direction in which the paper is transported from the paper discharge side to the paper supply side. Then, the color thermosensitive recording paper 5 is pressed and heated between the platen roller 6 and the thermal head 7 to sequentially record the three colors of yellow, magenta and cyan.

A fixing unit 9 for yellow and a fixing unit 10 for magenta for fixing the yellow thermosensitive coloring layer and the magenta thermosensitive coloring layer are arranged downstream of the conveying roller pair 4 in the forward direction. These fixing devices 9 and 10 are turned on when the color thermosensitive recording paper 5 is transported in the reverse direction.

As shown in FIG. 9A, there is also a color thermal printer in which a yellow fixing device 9 is disposed between a thermal head 7 and a pair of conveying rollers 4. In this color thermal printer, the ultraviolet rays radiated from the yellow fixing device 9 are arranged so as not to be blocked by the transport roller pair 4 and the thermal head 7, so that the color thermal printer shown in FIG. The apparatus size in the transport direction of the thermal recording paper 5 is reduced.

[0006]

As shown in FIG. 8B, in a capstan type color thermal printer using a pair of transport rollers, the leading edge 5a of the color thermal recording paper 5 has a thermal head 7 and a platen roller 6. Passing between
Since thermal recording is performed after being nipped by the transport roller pair 4, the distance L from the platen roller 6 to the transport roller pair 4 is L.
The length La2 obtained by adding the pinching margin α (for example, 1 mm) of the color thermosensitive recording paper 5 by the transport roller pair 4 to a1 becomes a blank portion where the thermal recording cannot be performed, which is formed on the leading edge 5a of the color thermosensitive recording paper 5. . To reduce the margin, La1 may be reduced, but this distance La1 is
Since the minimum gap is added to the radius Rp of the capstan roller 2 and the radius Rc of the capstan roller 2, there is a limit to reducing the value.

In a reciprocating color thermal printer, color thermal recording is performed by the pair of transport rollers 4 until thermal recording on all the thermal coloring layers is completed in order to prevent deviation of three color pixels. It is necessary that the paper 5 is nipped. However, if the yellow fixing device 9 is turned off while the rear end is nipped by the conveying roller pair 4, the portion facing the yellow fixing device 9 is insufficiently fixed. On the other hand, if the yellow fixing device 9 is kept lit, a portion near the magenta fixing device 10 is over-fixed. In order to properly fix the yellow thermosensitive coloring layer, the distance La3 from the transport roller pair 4 to the end of the yellow fixing device 9 (the width Ly of the yellow fixing device 9 + the radius Rn of the pinch roller 3 + the minimum gap).
And the length La4 obtained by adding the pinching allowance α by the conveying roller pair 4
May be a margin formed on the trailing edge 5b of the color thermosensitive recording paper 5. However, there is a problem that the margin La4 is about twice as large as the margin La2 of the leading edge 5a.

The margin La4 of the trailing edge 5b can be reduced by providing a shutter device or the like between the yellow fixing device 9 and the color thermosensitive recording paper 5 to adjust the irradiation amount.
Since the apparatus becomes large-sized and the cost is further increased, it cannot be used for a low-cost color thermal printer.

In the color thermal printer shown in FIG. 9A, as shown in FIG. 9B, a margin Lb4 at the trailing edge 5b is provided.
Can be made smaller than the margin La4 of the above-described color thermal printer by about the width Ly of the fixing unit 9 for yellow. However, the thermal head 7 and the transport roller pair 4
Is longer by the width Ly of the yellow fixing device 9, the margin Lb 2 formed on the leading edge 5 a of the color thermal recording paper 5 is larger than the margin La 2 of the color thermal printer described above. It becomes big.

Japanese Patent Laid-Open Publication No. Hei 8-156299 proposes a color thermal printer capable of reducing both the margins at the leading edge and the trailing edge of the color thermal recording paper. In this color thermal printer, a capstan roller is provided coaxially outside the platen roller, a pinch roller is provided facing the capstan roller, and a thermal head is arranged between the pinch rollers, and a yellow head is provided on the forward side of these rollers. A fixing lamp and a magenta fixing lamp are arranged. However, in this color thermal printer, the color thermal recording paper is conveyed only at both side edges, so that the conveyance is not stable, and there is a problem that uneven feeding or misregistration occurs and image quality is deteriorated. .

In the conventional color thermal printer, the diameter of the pinch roller is reduced in order to reduce the margin. However, when the pinch roller is thinner, the rigidity is reduced and the pinch roller is easily bent. When the pinch roller bends, there is a problem that the conveyance of the color thermosensitive recording paper becomes unstable, and uneven feeding and misregistration occur, thereby deteriorating the image quality. In order to solve this problem, it is considered that the pinch roller is formed into a tapered shape. However, the cost of the printer is increased, and if recording paper having different thicknesses is used, the conveyance becomes unstable.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to reduce the margin of a color thermosensitive recording paper without deteriorating an image.

[0013]

According to a first aspect of the present invention, there is provided a color thermal printer in which a diameter of one of a pair of conveying rollers is reduced and a deflection of the other roller is prevented. Pressing means for pressing the other fixing roller against the other roller at a uniform pressure, the first fixing device is disposed so as to face the pressing means and the one roller, and the first fixing device is disposed between the pressing means and the one roller. The color thermosensitive recording paper is irradiated with electromagnetic rays from both sides.

According to a second aspect of the present invention, in the color thermal printer, the area of the pressing means in the direction facing the first fixing device is set as follows.
It is the same as one roller or narrower than one roller.

Further, in the color thermal printer according to a third aspect of the present invention, the pressing means is constituted by a pressing roller contacting the one roller and a pressing member pressing the pressing roller toward the one roller.

Further, in the color thermal printer according to the present invention, the pressing means is constituted by a pressing plate abutting on one roller and a pressing member pressing the pressing plate toward the one roller.

[0017]

FIG. 1 schematically shows a color thermal printer according to the present invention. In this color thermal printer, a color thermal recording paper 16 is inserted from an insertion port 15 provided on the right side in the figure. The color thermosensitive recording paper 16 performs thermal recording and fixing of a full-color image while being reciprocated in the forward direction, which is the insertion direction, and in the reverse direction. The color thermal recording paper 16 on which the thermal recording has been completed is discharged from a discharge port 17 provided on the left side in the figure. In order to reduce the size of the printer, the distance from the insertion port 15 to the discharge port 17 is smaller than the length of the color thermosensitive recording paper 16 in the insertion direction.
A part of the color thermosensitive recording paper 16 that is reciprocating is always protruded from the insertion port 15 and the discharge port 17.

A thermal head 19 is located behind the insertion slot 15.
And a platen roller 20 are arranged opposite to each other. Further, a reflection type photosensor 21 for detecting the leading edge 16a of the color thermosensitive recording paper 16 and a pair of conveyance rollers 22 are arranged further behind.

The thermal head 19 has a heating element array 19a in which a number of heating elements are arranged in a line in a direction perpendicular to the direction in which the color thermosensitive recording paper 16 is conveyed.
As shown in the figure, it is movable between a thermal recording position where it is pressed against the color thermosensitive recording paper 16 and a retracted position where it is swung about the shaft attachment portion 24 to release the pressure contact. The heating element array 19a generates heat energy suitable for the thermosensitive coloring layer to be printed. The platen roller 20 is rotatable, and rotates following the transfer of the color thermosensitive recording paper 16.

The color thermosensitive recording paper 16 is, as is well known,
On a support, a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer, and a yellow thermosensitive coloring layer are sequentially provided. Top 1
The yellow thermosensitive coloring layer serving as the thermosensitive coloring layer has the highest thermal sensitivity and develops yellow with a small heat energy. The cyan thermosensitive coloring layer, which is the lowermost third thermosensitive coloring layer, has the lowest thermal sensitivity and develops cyan with a large thermal energy. The yellow thermosensitive coloring layer loses its coloring ability when irradiated with near-ultraviolet light of 420 nm. The magenta heat-sensitive coloring layer, which is the second heat-sensitive color-forming layer, develops magenta color with a thermal energy intermediate between that of the yellow heat-sensitive coloring layer and that of the cyan heat-sensitive coloring layer, and loses its coloring ability when irradiated with 365 nm ultraviolet rays. Further, the color thermosensitive recording paper 16 may be provided with, for example, a black thermosensitive coloring layer to form a four-layer structure. Further, the positions of the thermosensitive coloring layers may be exchanged.

The transport roller pair 22 includes a capstan roller 27 which is rotated in both directions by a motor 26, and a pinch roller 28 which is smaller in diameter than the capstan roller 27 and is rotatable. The transport roller pair 22 sandwiches the color thermal recording paper 16 inserted from the insertion opening 15 and transports the color thermal recording paper 16 in the forward direction and the reverse direction. Further, a pressing means for pressing the pinch roller 28 is provided above the transport roller pair 22 so as to prevent the pinch roller 28 from bending and to press the pinch roller 28 against the capstan roller 27 with a uniform pressure. A pressing roller 30 and a spring 31 as a pressing member are incorporated.

As shown in FIG. 2, the capstan roller 2
The pinch roller 7 and the pressing roller 30 are rotatably supported by a pair of bearing brackets 33 and 34. The capstan roller 27 is provided with bearing holes 33 a, formed below the bearing brackets 33, 34.
Both ends are inserted into 34a and rotatably supported, and are rotated in both directions by a motor 26 via a gear mechanism, a belt mechanism, and the like (not shown). Also, the capstan roller 27
Is formed of a metal such as iron, and the surfaces of both ends are knurled in order to increase the grip force when the color thermosensitive recording paper is transported.

The pinch roller 28 is mounted on the bearing bracket 3
3, 34 bearing holes 33 for capstan rollers 27
Both ends are inserted into elongated holes 33b and 34b formed above the upper and lower caps a and 34a and are rotatably supported, and move between a position where the capstan roller 27 is pressed and a position away from the capstan roller 27. Be free. The pinch roller 28 is also made of a metal such as iron as the capstan roller 27 and is formed in a rod shape.
The diameter is smaller than that.

The pressing roller 30 is provided on the bearing bracket 3.
3 and 34 are rotatably assembled above the pinch roller 28 using the long holes 33b, 34b.
4b. This pressing roller 30
Is an iron shaft 3 slightly smaller in diameter than the pinch roller 28.
0a, three roller portions 30 having the same diameter as the pinch roller 28.
b is provided, and both ends of the shaft portion 30a are urged downward from above by a spring 31 so that the roller portion 30b
Are pressed against the pinch roller 28. Accordingly, the pinch roller 28 is prevented from bending, and is pressed against the capstan roller 27 with a uniform pressure.

Above the transport roller pair 22, a yellow fixing device 36 is disposed. This yellow fixing device 3
Reference numeral 6 denotes a rod-shaped ultraviolet lamp 37 that emits near-ultraviolet light having a wavelength of 420 nm, and a reflector 38 that covers the ultraviolet lamp 37 from above and on both sides. Fixing unit for yellow 36
UV light is applied to the color thermosensitive recording paper 16 from both sides of the pinch roller 28 and the pressing roller 30 to fix the yellow thermosensitive coloring layer after the thermal recording.

It should be noted that, as shown in FIG. 3 (A), the amount of ultraviolet radiation radiated from the rod-shaped ultraviolet lamp 37 is usually largest immediately below the ultraviolet lamp 37. However, by arranging the reflector 38 having an appropriate shape around the ultraviolet lamp 37, the irradiation amount around the ultraviolet lamp 37 can be improved more than immediately below the ultraviolet lamp 37 as shown in FIG. Even if the ultraviolet lamp 37 is disposed so as to face the pinch roller 28 and the pressing roller 30, the ultraviolet irradiation can be performed without a decrease in the irradiation amount. Further, since the shaft portion 30a of the pressing roller 30 has a smaller diameter than the pinch roller 28 and the roller portion 30b has the same diameter as the pinch roller 28, the pressing roller 30 It does not interfere with UV irradiation.

A magenta fixing device 40 is disposed downstream of the yellow fixing device 36 on the forward side. The magenta fixing device 40 includes an ultraviolet lamp 41 that emits 365 nm ultraviolet light, and a reflector 42 that covers the ultraviolet lamp 41 above and on both sides. The magenta fixing device 40 irradiates the color thermosensitive recording paper 16 with ultraviolet rays to fix the magenta thermosensitive coloring layer after the thermal recording.

In the yellow fixing device 36, the position where the ultraviolet rays are not blocked by the thermal head 19, that is, the end surface 38a of the reflector 38 is located at the same position as the forward protrusion amount Ls of the thermal head 19 in the downstream direction. Are located in Since the transport roller pair 22 is disposed such that the pinch roller 28 is directly below the ultraviolet lamp 37, the distance Lc1 between the platen roller 20 and the transport roller pair 22 is Ls + Ly / 2, as shown in FIG. The margin Lc on the leading edge 16a side of the color thermosensitive recording paper 16
No. 2 is obtained by adding the nip margin α of the color thermosensitive recording paper 16 by the transport roller pair 22 to Lc1.

Further, the distance Lc from the conveying roller pair 22 to the end surface 38b of the reflector 38 of the yellow fixing device 36
In the portion No. 3, the fixing by the yellow fixing device 36 is insufficient or overfixed to the trailing edge 16 b of the color thermosensitive recording paper 16. Is the margin Lc4 on the rear edge 16b side of the color thermosensitive recording paper 16.

As a result, the margin Lc2 at the leading edge 16a of the color thermal recording paper 16 is (Ls + Ly) compared to the margin Lb2 at the leading edge of the conventional color thermal printer shown in FIG.
+ Rn)-(Ls + Ly / 2) = Rn + Ly / 2. Further, the margin Lc4 of the trailing edge 16b of the color thermal recording paper 16 is also (Ly) compared to the margin La4 of the trailing edge side of the conventional color thermal printer shown in FIG.
+ Rn) -Ly / 2 = Rn + Ly / 2.

Next, the operation of the above embodiment will be described. The color thermal printer shown in FIG. 1 is connected to, for example, a personal computer. If you have an image you want to print while using a personal computer,
An instruction to start printing is made after operating the keyboard of the personal computer. As a result, the print data is sent from the personal computer to the color thermal printer. The color thermal printer temporarily stores print data sent from a personal computer in a built-in memory.

After the print start operation, for example, a message indicating that the print preparation is completed and a message indicating that the color thermal recording paper 16 is to be inserted into the insertion slot 15 of the color thermal printer are displayed on the monitor of the personal computer, for example.

According to the message, the color thermosensitive recording paper 1
6 is inserted into the insertion slot 15. When not in use, the thermal head 19 swings about the shaft attachment portion 24 and is moved to a retracted position where the thermal head 19 is not pressed against the platen roller 20. Passing between the head 19 and the platen roller 20,
The leading end abuts on the transport roller pair 22. On the way, the leading edge 16a of the color thermosensitive recording paper 16 is detected by the reflective photosensor 21.

When the reflection type photo sensor 21 detects the leading edge 16a of the color thermosensitive recording paper 16, the motor 26 for the pair of conveying rollers 22 starts driving in response to the detection signal, and the capstan roller 27 is moved in the figure. Turn counterclockwise. The pinch roller 28 is pressed by the pressing roller 30 urged downward by the spring 31 and is in contact with the capstan roller 27.
, And rotate clockwise to rotate the color thermal recording paper 1
6. Nip the leading edge 16a of No. 6.

At the same time as the nip of the color thermal recording paper 16 by the transport roller pair 22, the thermal head 19
4 and moves to the thermal recording position, and the color thermosensitive recording paper 1 on the platen roller 20 is moved by the heating element array 19a.
Press 6.

The color thermosensitive recording paper 16 is composed of a pair of transport rollers 2.
It is transported in the forward direction by the forward rotation of No. 2. The platen roller 20 rotates counterclockwise following the transfer of the color thermosensitive recording paper 16. When the leading edge of the recording area reaches the heating element array 19a while the color thermosensitive recording paper 16 is being conveyed, each heating element generates heat energy corresponding to each pixel of the yellow image, and the yellow image is formed on the yellow thermosensitive coloring layer. Is thermally recorded line by line. The pinch roller 28 is pressed by the pressing roller 30 so as not to bend and is pressed against the capstan roller 27 with a uniform pressure, so that the transport of the color thermosensitive recording paper 16 during thermal recording is stabilized. The color thermal recording paper 16 on which the thermal recording of the yellow image has been performed passes below the yellow fixing device 36 and the magenta fixing device 40, and the leading end protrudes from the discharge port 16.

When the thermal recording on the yellow thermosensitive coloring layer of the color thermosensitive recording paper 16 is completed, the driving of the thermal head 19 is stopped and the thermal head 19 is moved to the retracted position. Immediately after this, the ultraviolet lamp 37 of the yellow fixing device 36 is turned on, and the transport roller pair 22 starts to rotate in the reverse direction, thereby transporting the color thermosensitive recording paper 16 from the rear edge 16 b toward the insertion slot 15.

When the color thermosensitive recording paper 16 is conveyed in the reverse direction, near-ultraviolet light of 420 nm emitted from the ultraviolet lamp 37 irradiates the color thermosensitive recording paper 16 and heats the next magenta thermosensitive coloring layer. Fix so that yellow does not develop.

The ultraviolet rays radiated from the ultraviolet lamp 37 are blocked by the pinch roller 28 and the pressing roller 30, but as shown in FIG. Since the amount of irradiation is larger in the periphery than in the periphery, the thermosensitive coloring layer for yellow can be fixed effectively. Further, the length L from the rear edge 16b of the color thermosensitive recording paper 16 toward the front end side is changed.
The portion c4 is a blank portion where thermal recording cannot be performed due to insufficient fixing or overfixing.
Is the width Ly of the yellow fixing unit 30 and the pinch roller 2 compared to the margin at the trailing edge of the conventional color thermal printer.
8 is reduced by the radius Rn.

When the leading edge of the recording area of the color thermosensitive recording paper 16 is transported again to the position of the heating element array 19a, the transport roller pair 22 stops once, and the ultraviolet lamp 37 is turned off. Then, the thermal head 19 returns to the thermal recording position again, and the transport roller pair 22 rotates forward to transport the color thermal recording paper 16 in the forward direction. The thermal head 19 performs thermal recording by applying thermal energy according to the magenta image to the magenta thermosensitive coloring layer. Also during the thermal recording of magenta, the pinch roller 28 is pressed by the pressing roller 30 so as not to bend and pressed against the capstan roller 27 with a uniform pressure. The conveyance is stable, and no misregistration occurs.

When the thermal recording of the magenta image is performed up to the rear end of the color thermal recording paper 16 in the forward direction, the thermal head 1
9 again moves to the retreat position to release the pressing on the color thermosensitive recording paper 16, and the transport roller pair 22 is stopped once. Just like in the case of yellow, the conveying roller pair 22 starts rotating in the reverse direction immediately after that, and at the same time, the ultraviolet lamp 41 of the magenta fixing device 40 is turned on. The magenta fixing device 40 irradiates the color thermosensitive recording paper 16 with ultraviolet light having a wavelength of about 365 nm, and fixes the color so that magenta does not develop during the next thermal recording of the cyan thermosensitive coloring layer.

When the leading edge of the recording area of the color thermosensitive recording paper 16 is conveyed to the position of the heating element array 19a, the thermal head 19 returns to the thermal recording position as described above. At the same time, the conveying roller pair 22 rotates forward to convey the color thermosensitive recording paper 16 in the forward direction. During this transport, the thermal head 19 thermally records a cyan image on the cyan thermosensitive coloring layer. Even during the thermal recording of the cyan image, the pinch roller 28 does not bend and is pressed against the capstan roller 27 with a uniform pressure, so that no registration error or the like occurs.

When the thermal recording on all the thermosensitive coloring layers is completed, the pair of transport rollers 22 discharges the color thermosensitive recording paper 16 from the discharge port 17 as it is. Note that the cyan thermosensitive coloring layer has no fixing property since the coloring heat energy has a value that does not cause coloring in a normal storage state, and the fixing units 36 and 40 do not operate.

In the above-described embodiment, the both ends of the pressing roller 30 are pressed by the springs 31 to prevent the pinch roller 28 from bending and to contact the capstan roller 27 with a uniform pressure. However, as shown in FIG. 5, a ring-shaped spring 45 is applied to the pressing roller 30 and the capstan roller 27, and the pinch roller 28 is pressed against the capstan roller 27 via the pressing roller 30 by the urging force of the spring 45. May be. Further, instead of the spring 45, a rubber band may be used.

The pinch roller 28 and the pressing roller 3
In the case where the diameter of the pinch roller 28 is made small and the bending of the pinch roller 28 cannot be prevented by the pressing roller 30, a pressing plate 47 that presses a central portion of the pinch roller 28 may be used as shown in FIG. Further, as shown in FIG. 7, the same effect can be obtained by pressing the pinch roller 28 with the two pressing rollers 49 and 50.

In each of the above embodiments, the position of the yellow fixing device is changed. However, among the yellow, magenta, and cyan thermosensitive coloring layers, for example, the magenta thermosensitive coloring layer is the uppermost layer, and the thermosensitive coloring layer from now on. When recording is performed, the present invention is applied to a magenta fixing device. Further, the color thermal printer has been described, but the present invention is also applicable to the monochrome thermal printer of the present invention.

[0047]

As described above, according to the color thermal printer of the present invention, the diameter of one roller of the conveying roller pair is reduced, the bending of one roller is prevented, and the other roller is pressed at a uniform pressure. Since the pressing means to press the roller is provided,
The color thermosensitive recording paper can be conveyed with high accuracy, and the deterioration of an image such as a registration error can be prevented. Further, since the first fixing device for fixing the first thermosensitive coloring layer on which the thermal recording is performed first is disposed so as to face the pressing means and one of the rollers, the color thermosensitive recording is compared with the conventional color thermosensitive printer. The margin between the leading edge and the trailing edge of the paper can be reduced by about half the width of the first fixing device.

Further, since the area of the pressing means in the direction facing the first fixing device is equal to or smaller than that of one roller, the fixing efficiency of the first fixing device does not decrease. .

Further, since the pressing means has a simple configuration including a pressing roller or a pressing plate and a pressing member for pressing these members toward one of the rollers, the cost can be reduced while maintaining the miniaturization of the printer. Can be adopted.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a color thermal printer of the present invention.

FIG. 2 is a perspective view showing a supporting form of a pair of conveying rollers and a pressing roller.

FIG. 3 is an explanatory diagram showing a distribution of an irradiation amount by an ultraviolet lamp.

FIG. 4 is an explanatory diagram showing margins of a color thermal recording sheet printed by the color thermal printer of the present invention.

FIG. 5 is an explanatory diagram showing another biasing method of the pressing roller.

FIG. 6 is a perspective view showing another embodiment of a method of pressing a pinch roller.

FIG. 7 is a perspective view showing still another embodiment of a method of pressing a pinch roller.

FIG. 8 is a schematic diagram showing a configuration of a conventional color thermal printer.

FIG. 9 is a schematic view showing a configuration of another conventional color thermal printer.

[Explanation of symbols]

 Reference Signs List 16 color thermal recording paper 19 thermal head 20 platen roller 22 conveyance roller pair 27 capstan roller 28 pinch roller 30 holding roller 31 spring 36 fixing device for yellow 40 fixing device for magenta

Claims (4)

[Claims] 1. At least first to first different colors
A third thermosensitive coloring layer is provided on the support, and
For the heat-sensitive coloring layer and the next second heat-sensitive coloring layer, color heat-sensitive recording paper provided with fixability by electromagnetic radiation in a wavelength range specific to each heat-sensitive coloring layer is used. A pair of transport rollers for reciprocating in the forward and reverse directions, a thermal head for heating and coloring each thermosensitive coloring layer in order from the first thermosensitive coloring layer during transport in the forward direction,
A first fixing device for irradiating an electromagnetic beam for fixing the thermosensitive coloring layer, and a second fixing device for irradiating an electromagnetic beam for fixing the second thermosensitive coloring layer; In the color thermal printer, the diameter of one roller of the transport roller pair is made smaller than the diameter of the other roller, and the one roller is prevented from bending and pressed against the other roller with uniform pressure. Providing a pressing means for pressing, arranging the first fixing device so as to face the pressing means and one roller, and irradiating the color thermosensitive recording paper with electromagnetic rays from both sides of the pressing means and one roller. A color thermal printer. 2. The color thermal printer according to claim 1, wherein the pressing unit has an area in a direction facing the first fixing unit equal to or smaller than the one roller. 3. The collar according to claim 1, wherein the pressing means includes a pressing roller that contacts one of the rollers, and a pressing member that presses the pressing roller toward the one of the rollers. Thermal printer. 4. The apparatus according to claim 1, wherein said pressing means comprises a pressing plate abutting on one roller, and a pressing member pressing said pressing plate toward said one roller.
Or a color thermal printer according to 2.