JP3710216B2 - Color thermal printing method and printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color thermal printing method and a printer, and more particularly, to a color thermal printing method and a printer which nip a recording paper and record a full color image by alternately feeding and returning.
[0002]
[Prior art]
In a color thermal printer, for example, a color thermal printer, color thermal recording paper is used, and a full color image is recorded in three-color plane order. This color thermosensitive recording paper has a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer, and a yellow thermosensitive coloring layer sequentially arranged on the base. The yellow thermosensitive coloring layer, which is the uppermost layer, has the highest thermal sensitivity and the lowest layer. The thermal sensitivity of the cyan thermosensitive coloring layer is the lowest. Each thermosensitive coloring layer is recorded in order from the top layer, but when recording the magenta thermosensitive coloring layer, a purple visible of 420 nm is visible after recording the yellow image so that the uncolored components in the yellow thermosensitive coloring layer do not color. Light fixing by irradiation with light. Similarly, after recording on the magenta thermosensitive coloring layer, the magenta thermosensitive coloring layer is photofixed by irradiating with 365 nm ultraviolet rays.
[0003]
In such a color thermal printer, as shown in FIG. 6A, a pair of conveying rollers 5 including a capstan roller 3 and a nip roller 4 is used to increase the feeding accuracy of the color thermal recording paper 2. Further, it is considered that the second nip roller 6 is provided on the capstan roller 3 to wind the recording paper 2 to increase the conveyance force of the recording paper 2 and eliminate the color misregistration of the three colors.
[0004]
[Problems to be solved by the invention]
However, when the recording paper 2 is wound around the capstan roller 3 simply to increase the conveying force, curling is generated by the conveying roller pair 5. In particular, the curl amount increases because the recording paper 2 is wound around the conveying roller pair 5 immediately after high heat is applied during thermal recording by the thermal head 7. Therefore, when the recording is finished, the curl amount of the recording paper 2 of the portion 2A sent by the conveying roller pair 5 is large, and the rear end portion 2B not sent by the conveying roller pair 5 is wound around the capstan roller 3. Therefore, the curl amount is reduced. Due to the difference in the curl amount, a curl inflection point PC is formed on the recording paper 2 as shown in FIG. Further, when the next color is thermally recorded due to the streaks, the touch of the thermal head 7 to the recording paper 2 is changed, which causes a problem of density unevenness. Such a problem also occurs in sublimation type and heat melting type thermal transfer systems in addition to thermal recording.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a color thermal printing method and a printer that eliminate the curl inflection point and improve printing quality.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention continues the feeding of the recording paper by the pair of conveying rollers immediately after finishing the thermal recording of each color. The edge of the recording paper is brought close to the pair of conveyance rollers, and the nip is continuously conveyed over the entire recording area during thermal recording of each color. It is what I did. Note that it is preferable that the feeding speed of the recording paper immediately after the completion of the thermal recording is the same as that during the thermal recording. Further, it is preferable to release the pressing of the thermal head to the recording paper without stopping the feeding of the recording paper. Further, it is preferable that the conveying roller pair includes a capstan roller and a nip roller, and the nip roller is brought into rolling contact with the peripheral surface of the capstan roller to change the winding angle of the recording paper around the capstan roller. Furthermore, it is preferable to adjust the curl amount of the recording paper by changing the winding angle.
[0007]
The color thermal printer of the present invention uses a recording paper roll, and includes a conveying roller pair, a capstan roller around which the recording paper is wound, a nip roller that nips the recording paper together with the capstan roller, and a recording paper winding. And a holding member for maintaining the hanging angle, and immediately after the thermal recording of each color is finished, the feeding of the recording paper by the conveying roller pair is continued. The edge of the recording paper is brought close to the pair of conveyance rollers, and the nip is continuously conveyed over the entire recording area during thermal recording of each color. It is what I did. In addition, according to the present invention using cut sheet type recording paper, The color thermal printer continues to feed the recording paper by the pair of transport rollers immediately after finishing the thermal recording of each color. The edge of the recording paper is brought close to the pair of conveyance rollers, and the nip is continuously conveyed over the entire recording area during thermal recording of each color. It is what I did. It is preferable to provide a winding angle adjusting means to change the curling amount by changing the winding angle. The winding angle adjusting means is preferably configured to adjust the winding angle of the recording paper on the capstan roller by rolling the nip roller to the peripheral surface of the capstan roller.
[0008]
[Action]
At the time of printing, a first color image, for example, a yellow image is thermally recorded line by line by a thermal head while recording paper is fed by a pair of conveying rollers. Immediately after the end of this thermal recording, the recording paper feed continues. When the end of the recording paper comes close to the conveyance roller pair, the feeding of the recording paper is stopped. Next, the recording paper is returned by feeding a predetermined amount in the direction opposite to the feeding direction during thermal recording. Next, after the second color image, for example, a magenta image, is recorded line by line in the same manner and the recording is finished, the recording paper is fed until the end of the recording paper comes close to the pair of conveyance rollers. Then, the recording paper is returned to a predetermined position. Thereafter, the third color image, for example, a cyan image is recorded in the same manner, and after the recording is finished, the recording paper is fed until the end of the recording paper comes close to the pair of conveyance rollers, and then discharged. . As the recording paper, a recording paper roll wound in a roll form or a cut sheet type recording paper is used. Even after the thermal recording of the recording paper is finished, the feeding is continued until at least the end of the recording unit approaches the pair of conveyance rollers, so that the entire area of the recording paper is fed to the pair of conveyance rollers. Accordingly, curl inflection points do not occur on the recording paper, and deterioration in print quality due to generation of streaks due to the inflection points is prevented.
[0009]
Further, by changing the rolling contact position of the nip roller with respect to the capstan roller, the winding angle of the recording paper around the capstan roller is changed. When the winding angle increases, the curl amount of the recording paper increases, and when the winding angle decreases, the curl amount of the recording paper decreases. Therefore, the curl amount of the recording paper can be adjusted by changing the winding angle. Further, when a recording paper roll is used as the recording paper, the curl is effectively removed by setting the curl amount in the direction opposite to the curl so as to eliminate the curl due to the roll form.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, a recording paper roll 10 is housed in a magazine 11 so as to be rotatable. A shutter 13 and a pair of paper feed rollers 14 are provided in the magazine near the outlet 12 of the magazine 11. The shutter 13 opens and closes the outlet 12. In the storage state, the shutter 13 is urged by a spring material or the like to close the outlet 12, and is protected from moisture and light. When a paper feed instruction is issued after the magazine 11 is set in the thermal printer, the shutter 13 is displaced upward by the shutter opening mechanism 9 on the printer side, and the outlet 12 is opened.
[0011]
The pair of paper feed rollers 14 is rotated after the shutter 13 is set in the open state, and feeds the leading end of the recording paper 16 toward the nip conveyance unit 15. The pair of paper feed rollers 14 includes a capstan roller on the upper side and a nip roller on the lower side, and feeds the recording paper 16 at the same feed speed as the nip transport unit 15. When the roller shift mechanism 14a feeds the leading edge of the recording paper 16 toward the nip conveyance section 15, the pair of paper feed rollers 14 is brought into a nip state where the recording paper 16 is nipped, and thereafter, the one-frame printing sequence is finished. Until the nip roller is released from the capstan roller.
[0012]
When the magazine 11 is set in the thermal printer, the pair of paper feed rollers 14 is rotationally driven by a motor on the printer side, whereby the leading edge of the recording paper 16 is pulled out from the recording paper roll 10 and fed toward the nip transport unit 15. It is done. As is well known, the recording paper 16 has a cyan thermosensitive color developing layer, a magenta thermosensitive color developing layer, and a yellow thermosensitive color developing layer in order, and the uppermost yellow thermosensitive color developing layer has the highest thermal sensitivity. The yellow thermosensitive coloring layer loses its coloring ability by violet visible light of 420 nm, and the magenta thermosensitive coloring layer loses its coloring ability by 365 nm ultraviolet light.
[0013]
The magazine 11 is made larger than the maximum winding diameter of the recording paper roll 10, and a gap is provided between the inner wall surface of the magazine 11 and the recording paper roll 10. As shown in FIG. 2, when the recording paper 16 is pulled back by the nip conveyance unit 15, the returned portion is wound and stored in this gap.
[0014]
As shown in FIG. 1, the nip conveyance unit 15 includes a capstan roller 20 and first and second nip rollers 21 and 22. The first nip roller 21 is rotatably attached to the tip of the swing arm 23 so that the rolling contact position with the capstan roller 20 can be displaced. The second nip roller 22 is fixed at the rolling contact position with the capstan roller 20. These first and second nip rollers 21 and 22 are provided with roller shift mechanisms 24 and 25 so as to be displaced between a nip position pressed against the peripheral surface of the capstan roller 20 and a retracted position away from the nip position. It is configured. The roller shift mechanisms 24 and 25 are constituted by solenoids. Alternatively, the nip rollers 21 and 22 may be shifted using cams rotated by a motor. The nip transport unit 15 is brought into a nip release state by the shift mechanisms 24 and 25 when the leading edge of the recording paper 16 is transported from the pair of paper feed rollers 14, and is kept in a nip state after the paper feed until the print sequence is completed. The
[0015]
The swing arm 23 is rotatably attached to the shaft 20a of the capstan roller 20, and a rolling contact position of the first nip roller 21 on the peripheral surface of the capstan roller 20 by a displacement mechanism 26 including a motor and a reduction gear. Is configured to be displaced. Therefore, when the swing arm 23 rotates counterclockwise, the angle at which the recording paper 16 is wound around the capstan roller 20 is increased. In addition, when the swing arm 23 is rotated in the clockwise direction, the winding angle is reduced.
[0016]
The nip transport unit 15 is disposed obliquely above the outlet 12 of the magazine 11, and the color thermal recording paper 16 is wound around the capstan roller 20 of the nip transport unit 15 to be stored in a roll form. The recording paper 16 is curved in a direction opposite to the curl due to the above, and the curl is corrected. A guide plate 27 is provided between the outlet 12 and the nip transport unit 15, and the leading edge of the recording paper 16 is guided to the nip transport unit 15 when the paper feed roller pair 14 feeds the paper. When the recording paper 16 is pulled back, the recording paper 16 is returned into the magazine 11, and the recording paper 16 is stored in a relaxed state as shown in FIG.
[0017]
A platen roller 30 and a thermal head 31 are disposed downstream of the nip conveyance unit 15. In the present embodiment, the thermal head 31 is attached in a fixed state. The platen roller 30 is made of hard rubber and is rotatable. The platen roller 30 is mounted so as to be movable up and down by an up / down mechanism 32, and is displaced upward during thermal recording to press the recording paper 16 against the heating element array 31a of the thermal head 31.
[0018]
A heat generating element array 31 a is formed on the thermal head 31. In the heating element array 31a, a large number of heating elements are formed in a line shape in the axial direction of the platen roller 30, and each heating element is driven in accordance with image data during thermal recording, so that the three color planes are sequentially arranged. Record a full color image.
[0019]
A cutter 33 is disposed downstream of the thermal head 31. The cutter 33 has a movable upper blade and a fixed lower blade. After recording a full-color image, the cutter 33 operates to cut the recorded portion into a sheet. A sensor 34 that detects the leading edge of the recording paper 13 is provided near the nip conveyance unit 15 and downstream.
[0020]
A light fixing device 35 is disposed downstream of the cutter 33. The optical fixing device 35 includes a yellow fixing lamp 36 that emits violet visible light having a wavelength of 420 nm, a magenta fixing lamp 37 that emits ultraviolet light having a wavelength of 365 nm, and a lamp house 38. The lamp house 38 is rotated 180 degrees by the motor 39 about the mounting shaft 38a, and either of the lamps 36 and 37 is selectively set at a fixing position facing the recording paper 16.
[0021]
A pair of paper discharge rollers 40 is disposed downstream of the optical fixing unit 35, and a sheet cut into a sheet is nipped and discharged from a paper discharge port. Although not shown, a guide plate is disposed between the nip transport unit 15 and the paper discharge port, and a transport path for the recording paper 16 is formed by the guide plate. As a matter of course, there is no guide plate in the portion of the cutter 33 and the platen roller 30. An irradiation opening is formed in the guide plate at the irradiation position of the optical fixing device 35.
[0022]
In FIG. 3, the operation unit 42 includes a print start key and sends various commands to the controller 43. The controller 43 includes a shutter opening mechanism 9, drivers 44 and 45, a cutter driving unit 46, an up / down mechanism 32, a print control unit 48, a ramp control unit 49, roller shift mechanisms 14 a, 24, 25, 40 a, and a displacement mechanism 26. Control.
[0023]
The controller 43 sends a rotation direction signal and a drive pulse to the driver 44. The driver 44 rotates the pulse motor 52 in the normal direction or the reverse direction, and rotates the capstan roller of the paper feed roller pair 14, the nip transport unit 15, and the paper discharge roller pair 40 in the normal direction or the reverse direction. The counter 53 starts a count operation from the time when the tip detection signal of the sensor 34 is input, counts up when the pulse motor 52 rotates forward, and counts down when it reverses. The driver 45 controls the rotation of the motor 39 to rotate the lamp house 38.
[0024]
The cutter driving unit 46 moves the movable blade of the cutter 33 up and down, cuts it from the planned cutting line, and cuts the printed part into sheets. The up / down mechanism 32 is composed of a motor and a cam, and raises the platen roller 30 at the pressing position to press the recording paper 16 against the heating element array 31 a of the thermal head 31. In the retracted position, the platen roller 30 is lowered to a position where the recording paper 16 is separated from the heating element array 31a. The print control unit 48 includes a memory storing three-color image data for one frame and a head driver, and drives each heating element of the thermal head 31 according to the image data of each color. These heating elements generate heat according to the image data and the color to be recorded, and develop the recording paper 16 to a desired density.
[0025]
The lamp controller 49 controls the light emission of the yellow fixing lamp 36 and the magenta fixing lamp 37. The roller shift mechanisms 14a, 24, 25, and 40a are composed of solenoids or the like, and move the nip rollers of the paper feed roller pair 14, the nip transport unit 15, and the paper discharge roller pair 40.
[0026]
Next, the operation of the above embodiment will be described. As shown in FIG. 1, when the recording paper roll 10 is replaced, a new magazine 11 is set at the storage position. As shown in FIG. 2, after the image data to be printed is captured, if the operation unit 42 is operated to indicate printing, the controller 43 first controls the shutter opening mechanism 9 to move the shutter 13 of the magazine 11. Open. The leading edge of the recording paper 16 is stored in the magazine 11 while being nipped by the pair of paper feed rollers 14, and the leading edge of the recording paper 16 faces the entrance of the guide plate 27 when the shutter 13 is opened. Next, the controller 43 rotates the pulse motor 52 via the driver 44. The pulse motor 52 rotates the paper feed roller pair 14 to pull out the recording paper 16 from the recording paper roll 10 and send it out toward the nip conveying section 15 in the nip released state. When the leading edge of the recording paper 16 reaches the sensor 34, a leading edge detection signal from the sensor 34 is sent to the controller 43.
[0027]
When the controller 43 receives the leading edge detection signal, the controller 43 moves the nip rollers 21 and 22 via the roller shift mechanisms 24 and 25 to bring the nip conveyance unit 15 into a nip state. Since the capstan roller 20 is rotated by the pulse motor 52, the recording paper 16 is conveyed when the capstan roller 20 is in the nip state. Further, the counting operation of the counter 53 is started from the point of detection of the leading edge, and the number of driving pulses to the pulse motor 52 is counted to measure the amount of recording paper 16 delivered.
[0028]
During feeding of the recording paper 16, the platen roller 30 is separated from the thermal head 31, and is conveyed toward the optical fixing device 35 through these. The sending amount of the recording paper 16 is measured by the counter 53, and the driver 44 stops the pulse motor 52 when the count value reaches a predetermined set value. By sending out the recording paper 16, the recording area is positioned on the downstream side of the heating element array 31a.
[0029]
Next, the controller 43 reverses the pulse motor 52 via the driver 44 and starts the first pull-back of the recording paper 16. The pulled-back recording paper 16 is returned into the magazine 11 through the guide plate 27, and the recording paper roll 10 is wound and stored.
[0030]
Further, the counter 53 counts down while the recording paper 16 is pulled back. From the contents of the counter 53, the position of the rear end of the recording area can be known. In this embodiment, the end of the recording area located on the front end side of the recording paper is the front end, and the end of the recording area located on the recording paper roll 10 side is the rear end. Will be started. When the rear end of the recording area approaches the thermal head 31, the controller 43 lifts the platen roller 30 upward via the up / down mechanism 32 and presses the recording paper 16 against the heating element array 31 a of the thermal head 31.
[0031]
When the heating element array 31a faces the rear end of the recording area, the print control unit 48 drives the thermal head 31 according to the yellow image data to record the yellow image line by line. The pulling speed of the recording paper 16 may be the same for all three colors, but may be changed for each color in order to perform high-speed printing. In this case, since the yellow image is colored with the smallest heat energy, the pullback speed is made fastest, and the cyan image is recorded with the slowest pullback speed. In this embodiment, since the color thermal recording paper is simply sent out, the printing speed may be increased by making the sending speed faster than the pull-back speed.
[0032]
When a yellow image is recorded in the recording area, the up / down mechanism 32 retracts the platen roller 30 downward to release the pressing of the recording paper 16 against the thermal head 31. In addition, the recording paper 16 is continuously pulled back after the yellow image recording is completed. When the leading edge of the recording paper 16 is detected by the sensor 20, the reverse rotation of the pulse motor 52 is stopped and the counter 53 is reset. As a result, as shown in FIG. Therefore, as shown in FIG. 6 (A), unlike the case where the pull-back is stopped and sent out immediately after the recording is finished, a curl inflection point occurs on the recording paper 16 as shown in FIG. 6 (C). There is no. Moreover, the curl of the recording paper becomes almost uniform. Therefore, in the next magenta recording, the head touch of the thermal head does not change at the curl inflection point, and the occurrence of density unevenness can be suppressed.
[0033]
When the pulse motor 52 rotates in the forward direction again for the second delivery of the recording paper 16, the recording paper 16 stored in a slackened state in the magazine 11 is sent out by a predetermined amount. During the second delivery, the yellow fixing lamp 36 is lit and irradiated with a purple visible light of 420 nm to lightly fix the yellow image in the recording area. When the end of the light fixing for the recording area is detected based on the count value of the counter 53, the feeding of the recording paper 16 is stopped. Further, the yellow fixing lamp 36 is turned off. Thereafter, the pulse motor 52 is reversely rotated and the recording paper 16 is pulled back. After the yellow fixing lamp 36 is turned off, the lamp house 38 is rotated 180 degrees by the rotation of the motor 39 for the next magenta fixing.
[0034]
When the rear end of the recording area approaches the heating element array 31a, the platen roller 30 is raised as described above to press the recording paper 16 against the heating element array 31a. When the heating element array 31a reaches the rear end of the recording area, the thermal head 31 is driven according to the magenta image data, and a magenta image is recorded on the recording paper 16 line by line. In this magenta image recording, the thermal head 31 generates larger thermal energy than the yellow image recording. Even after the recording of the magenta image, the leading edge of the recording paper 16 is pulled back to the vicinity of the nip conveyance unit 15, so that the recording paper 16 becomes a substantially uniform curl.
[0035]
After the recording of the magenta image, the recording paper 16 is fed out as described above, and during this feeding, the magenta fixing lamp 37 is turned on and the magenta image in the recording area is light-fixed by irradiation with 365 nm ultraviolet rays. After the magenta image is light-fixed, the feeding of the recording paper 16 is stopped and the recording paper is pulled back.
[0036]
During the third pull-back, the thermal head 31 generates the largest thermal energy according to the cyan image data, and records a cyan image line by line in the recording area. When the cyan image recording is completed, a full-color image is formed in the recording area. After the cyan image is recorded, the platen roller 30 is separated from the thermal head 31. When the recording paper 16 is continuously pulled back and the leading edge of the recording paper 16 is detected by the sensor 34, the reverse rotation of the pulse motor 52 is stopped and the third pulling is completed, and the counter 53 is reset at the same time. The Further, the lamp house 38 is rotated 180 degrees.
[0037]
Next, the pulse motor 52 rotates forward to feed the recording paper 16. Also at this time, the counter 53 counts the drive pulse and checks the position of the planned cutting line. Then, when this planned cut line comes to the position of the cutter 33, the pulse motor 52 is temporarily stopped. Next, the cutter driving unit 46 operates the cutter 33 to cut the recording paper 16 along the planned cutting line and cut it into a sheet-like print.
[0038]
When the cut print is cut, the leading edge reaches the discharge roller pair 40. The paper discharge roller pair 40 is in a nip state when the nip roller is moved after being cut. Then, only the paper discharge roller pair 40 rotates to discharge the sheet-like print from the paper discharge port to a tray or the like. Further, the new leading edge of the recording paper 16 is stopped at the cutting position.
[0039]
When printing is again instructed by the operation unit 42, the nip conveyance unit 15 sends out the leading edge of the recording paper 16. During feeding of the recording paper 16, the platen roller 30 is separated from the thermal head 31, and is conveyed toward the optical fixing device 35 through these. The sending amount of the recording paper 16 is continuously measured by the counter 53, and the driver 44 stops the pulse motor 52 when the content matches the set value. As a result, the recording paper 16 is sent out until the rear end of the recording area is positioned downstream of the heating element array.
[0040]
Next, the controller 43 reverses the pulse motor 52 via the driver 44 and starts the first pull-back of the recording paper 16. Thereafter, a full-color image is recorded by pulling it back three times according to the above-described procedure, and finally it is cut into sheets and discharged.
[0041]
When changing the type of the recording paper 16, the recording paper type is input via the operation unit 42. Since the degree of curl changes depending on the thickness of the recording paper 16 and the material of the base member, even when the type of the recording paper 16 is changed, the capstan roller 20 of the nip conveying unit 15 is always used to make the curl almost constant. The winding angle of the recording paper 16 is changed. When it is desired to increase the curl amount, the winding angle is increased. When it is desired to decrease the curl amount, the winding angle is decreased. The relationship between the winding angle and the curl amount is obtained in advance for each type of the recording paper 16 through experiments or the like, and this relationship is stored in the memory 43 a in the controller 43. Therefore, when the type of recording paper is input, the controller 43 operates the displacement mechanism 26 using the winding angle corresponding to this, and sets the rolling contact position of the first nip roller 21 on the peripheral surface of the capstan roller 20. Change and set the winding angle to match the recording paper used.
[0042]
In addition to changing the wrapping angle in order to keep the curl amount constant, the wrapping angle may be changed to eliminate curl. Also in this case, the winding angle for removing the curl is previously determined for each type of the recording paper 16.
[0043]
In the above embodiment, the recording paper roll 10 is used. However, as shown in FIG. 4, a cut sheet type recording paper may be used. In this case, a paper feed roller 72 is provided, which is brought into contact with the uppermost layer of the recording paper 71 in the tray 70, and the recording paper 71 is sent to the transport path 73 by the rotation of the paper feed roller 72. The paper feed path 74 is formed so as to obliquely intersect the transport path 73, and the rear end of the recording paper 71 does not enter the paper feed path 74 when the recording paper 71 is pulled back. Be guided to.
[0044]
In the conveyance path 73, a thermal head 76, a platen roller 77, a nip conveyance unit 78, and a light fixing unit 79 are provided in this order. The recording paper 71 sent out from the paper supply tray 70 passes between the thermal head 76 and the platen roller 77 in the retracted position, and is sent to the nip conveyance unit 78. The nip conveyance unit 78 includes a capstan roller 78a and first and second nip rollers 78b and 78c. The first nip roller 78b adjusts the winding angle of the recording paper 71 around the capstan roller 78a. It is attached to the swing arm 78d. The swing arm 78d is rotatably attached to the shaft of the capstan roller 78a. Further, the optical fixing device 79 and the guide plate 80 are also integrally attached to the swing arm 78d so that the interval between the optical fixing device 79 and the recording paper 71 is not changed by changing the winding angle of the recording paper 71. ing. The nip rollers 78b and 78c are set to a nip state or a nip release state by a roller shift mechanism (not shown).
[0045]
When the leading edge of the recording paper 71 passes through the nip transport section 78, the sensor 81 detects this and changes the nip transport section 78 from the nip release state to the nip state. Thereafter, the recording paper 71 is fed by the nip conveyance unit 78, and when the thermal head 76 approaches the recording area, the thermal head 76 is set to the pressing position, and the yellow image is recorded line by line by the thermal head 76. The yellow recorded portion is optically fixed by the yellow fixing lamp 82 of the optical fixing unit 79. Next, after the thermal head 76 is moved to the retracted position, the capstan roller 78a of the nip conveyance unit 78 is reversely rotated to pull back the recording paper 71 by a predetermined amount. Thereafter, the capstan roller 82 rotates forward, and the magenta image is recorded line by line in the same manner in the recording area while feeding the recording paper 71. The magenta recorded portion is optically fixed by a magenta fixing lamp 84 of the optical fixing unit 79. Next, the recording paper 71 is pulled back by a predetermined amount by the nip conveyance unit 78. Thereafter, a cyan image is recorded line by line in the recording area while feeding the recording sheet 71 by the nip conveyance unit 78. After the cyan image is recorded, the recording paper 71 is pulled back by the nip conveyance unit 78 and sent to the paper discharge path 75. Then, the recording paper 71 is discharged by the paper discharge roller pair 83.
[0046]
Also in this embodiment, the feeding of the recording paper 71 is continued immediately after the end of the thermal recording, and the trailing edge 71a of the recording paper is sent to the vicinity of the nip conveying portion 78. In addition to being constant, there is no occurrence of curl inflection points in the recording paper 71. In this embodiment, the optical fixing device 79 and the guide plate 80 are integrally provided on the swing arm 78d, and these are changed in accordance with the change in the winding angle of the recording paper. However, these are fixed. It may be attached. In this case, a guide roller is provided to make the positional relationship between the optical fixing device and the recording paper constant regardless of the winding angle of the recording paper.
[0047]
In the above embodiment, the recording sheets 16 and 71 are wound around the capstan rollers 20 and 78a by the first and second nip rollers 21, 22, 78b and 78c. In addition, the rolling contact position is fixed. Instead of the nip rollers 21 and 78c, another pressing member may be used to wind the recording paper 16 around the capstan roller 20 at a predetermined angle. As the pressing member, a guide member urged by a spring material, a guide member made of a spring material, or the like can be used.
[0048]
In the above embodiment, the swing arms 23 and 78d are used to change the rolling position of the first nip rollers 21 and 78b to the peripheral surfaces of the capstan rollers 20 and 78a. As shown in FIG. 2, the rolling contact position of the first nip roller 92 to the capstan roller 93 may be changed by using two swing levers 90 and 91. In this case, the first nip roller 92 is rotatably provided at the distal end of the second lever 91, and the second lever 91 is rotatably attached to the distal end of the first lever 90 via the attachment shaft 94. A coil spring 95 is provided between the first lever 90 and the second lever 91 to urge the first nip roller 92 so as to always contact the peripheral surface of the capstan roller 93. Then, the first lever 90 is rotated by a predetermined angle about the attachment shaft 96 by the displacement mechanism 26. Thereby, the winding angle of the recording paper 97 can be changed. In addition, the same code | symbol is attached | subjected to the same component as what is shown in FIG.
[0049]
A stopper 98 is attached to the second lever 91 to restrict clockwise rotation of the second lever 91 by a predetermined angle or more. Therefore, when the first lever 90 is rotated counterclockwise by the displacement mechanism 26, the nip roller 92 is separated from the capstan roller 93 at a point exceeding the minimum winding angle, and the pressure bonding is released. Thus, in this embodiment, the nip can be released in addition to the adjustment of the winding angle. Reference numeral 99 denotes a second nip roller that is moved up and down by a roller shift mechanism (not shown).
[0050]
In each of the above-described embodiments, the optical fixing is performed at the time of either sending out or pulling back the recording paper. However, the fixing may be performed by both sending and pulling back. In the color thermal recording paper, the unrecorded portion is light yellow, but is bleached when irradiated with ultraviolet rays from a magenta fixing lamp. In the case of fixing a yellow image, if the irradiation amount of purple visible light is too large, the color development characteristic of magenta is deteriorated, so it is necessary to pay attention to overfixing. However, since the problem of overfixing does not occur in the magenta image, the magenta fixing lamp may be kept on after the magenta image is recorded until the paper discharge is completed.
[0051]
In addition, when the width of the irradiation area of the optical fixing unit 35 (the length in the recording paper feeding direction) is wide, the front end portion and the rear end portion of the recording area stop without passing through the irradiation area, so that When uneven fixing occurs, a shutter may be provided in the irradiation area, and the shutter may be opened and closed in conjunction with the feeding of the recording paper to make the integrated fixing light amount distribution uniform in the light fixing area. Further, in addition to correcting fixing unevenness by the shutter, a portion where uneven fixing occurs may not be used for recording. Further, when the margin increases, this portion may be cut off with a cutter.
[0052]
Further, instead of the platen rollers 30 and 77, a fixed plastic template may be used. Further, in the above-described embodiment using the recording paper roll, the recording paper roll is simply wound and loosened when the recording paper is pulled back. However, the recording paper may be stored in a loop in the loop forming unit. . In addition to winding and loosening, the recording paper roll 10 may be wound. Further, the paper feed roller pair, the nip transport unit, and the paper discharge roller pair may be always in the nip state and sent at the same feed speed in the same direction as the nip transport unit. Further, the positions of the cutter, the optical fixing device and the like may be changed as appropriate. In the above embodiment, the present invention is applied to a color thermal printer. However, the present invention may be applied to a sublimation type or fusion type color thermal transfer printer. It can be suppressed and the curl can be made almost uniform.
[0053]
【The invention's effect】
According to the present invention, when the recording paper is wound around the capstan roller in order to increase the conveying force and increase the feeding accuracy of the recording paper, streaks and density unevenness due to the curl inflection point due to the winding are caused. Occurrence can be suppressed. That is, even after the thermal recording of each color for the recording area is completed, the recording paper is continuously fed until the end of the recording unit approaches the pair of conveying rollers, so that the nip conveyance is performed on the entire recording unit. For this reason, curl inflection points do not occur in the recording section, and streaks due to the inflection points and print quality deterioration due to the streaks are eliminated.
[0054]
Further, since the feeding speed of the recording paper after the completion of the thermal recording is made the same as the feeding speed at the time of thermal recording, it is possible to suppress the fluctuation of the curl amount by the nip conveyance unit. Furthermore, since the thermal head is released from pressing the recording paper without stopping the feeding of the recording paper, the fluctuation of the curl amount by the nip conveying section can be further suppressed.
[0055]
Since the nip roller is brought into rolling contact with the peripheral surface of the capstan roller to change the winding angle of the recording paper around the capstan roller, the amount of curling applied to the recording paper can be controlled. Accordingly, the curl amount can be made substantially constant over the entire length of the recording paper, or the curl can be easily removed when the recording paper roll is used.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a color thermal printer of the present invention using a recording paper roll.
FIG. 2 is a schematic diagram illustrating a state in which the leading end of the recording paper is pulled back to the vicinity of the nip conveyance unit.
FIG. 3 is a block diagram illustrating an electrical configuration of a color thermal printer.
FIG. 4 is a schematic view showing a color thermal printer of the present invention using cut sheet type recording paper.
FIG. 5 is a schematic view showing another winding angle adjusting means using two swing levers.
6A is a schematic diagram showing a state immediately after the thermal recording is finished by winding the recording paper on the capstan roller, and FIG. 6B is a case where the recording paper is fed in the state of FIG. FIG. 3C is a side view showing an example of the curling of the recording paper, and FIG. 3C is a side view showing an example of the curling of the recording paper when the recording paper is pulled back to the state shown in FIG.
[Explanation of symbols]
10 Recording paper roll
11 Magazine
14 Paper feed roller pair
15, 78 Nip transport section
16, 71, 97 color thermal recording paper
20, 78a, 93 Capstan roller
21, 22, 78b, 78c, 92, 98 Nip rollers
23, 78d swing arm
31,76 Thermal head
35,79 Light fixing device
40 Paper discharge roller
70 Paper tray
72 Feed roller
90, 91 Swing lever

Claims (8)

The recording paper is wound around one roller of the pair of conveying rollers and the recording paper is nipped by the other roller, and the recording paper is fed out and pulled back alternately, and recording is performed during the feeding or the pulling back. In a color thermal printing method in which thermal recording of at least three colors is sequentially performed on a recording area of paper with a thermal head.
Immediately after the thermal recording of each color is finished, the recording paper is continuously fed by the pair of conveyance rollers so that the end of the recording paper is brought close to the pair of conveyance rollers, and the entire recording area is continuously recorded during the thermal recording of each color. A color thermal printing method characterized by carrying out nip conveyance.   2. The color thermal printing method according to claim 1, wherein the feeding speed of the recording paper immediately after the thermal recording is made the same as the feeding speed at the time of thermal recording.   3. The color thermal printing method according to claim 1, wherein the thermal head is released from pressing the recording paper without stopping the feeding of the recording paper.   The conveyance roller pair includes a capstan roller and a nip roller, and the nip roller is brought into rolling contact with a peripheral surface of the capstan roller to change a winding angle of the recording paper around the capstan roller. The color thermal printing method according to any one of 1 to 3.   5. The color thermal printing method according to claim 4, wherein the curl amount of the recording paper is adjusted by changing a winding angle of the recording paper around the capstan roller. A supply unit in which the recording paper roll is set, a conveyance roller pair that alternately feeds and pulls out the recording paper drawn from the recording paper roll, and a downstream side of the conveyance roller pair when the recording paper is fed The image is thermally recorded with the first color in the recording area of the recording paper at the first pull-back, the image is thermally recorded with the second color at the second pull-back, and at the third pull-back. A thermal head that thermally records an image in the third color, and arranged between the supply unit and the conveyance roller pair, between the conveyance roller pair and the thermal head, or downstream of the thermal head, and to cut the recording paper In a color thermal printer equipped with a cutter for cutting on a position and cutting into a sheet,
The pair of conveying rollers includes a capstan roller around which the recording paper is wound, a nip roller that nips the recording paper together with the capstan roller, and a pressing member for maintaining the winding angle of the recording paper.
Immediately after the thermal recording of each color is finished, the recording paper is continuously fed by the pair of conveyance rollers so that the end of the recording paper is brought close to the pair of conveyance rollers, and the entire recording area is continuously recorded during the thermal recording of each color. A color thermal printer characterized by carrying out nip conveyance . A pair of conveying rollers that nips and feeds a cut sheet type recording sheet fed from the sheet feeding tray alternately, and is disposed between the pair of conveying rollers and the sheet feeding tray. The image is thermally recorded in the recording area of the recording paper at the time of delivery, the image is thermally recorded in the second color at the second delivery, and the third color is delivered at the third delivery. In a color thermal printer equipped with a thermal head for thermal recording of images,
The pair of conveying rollers includes a capstan roller around which the recording paper is wound, a nip roller that nips the recording paper together with the capstan roller, and a pressing member for maintaining the winding angle of the recording paper.
Immediately after the thermal recording of each color is finished, the recording paper is continuously fed by the pair of conveyance rollers so that the end of the recording paper is brought close to the pair of conveyance rollers, and the entire recording area is continuously recorded during the thermal recording of each color. A color thermal printer characterized by carrying out nip conveyance .   There is provided a winding angle adjusting means for adjusting the winding angle of the recording paper to the capstan roller by rolling the nip roller to the peripheral surface of the capstan roller, and the winding angle is changed by the winding angle adjusting means. 8. A color thermal printer according to claim 6, wherein the amount of curling applied to the recording paper is changed.

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