JPH0727851U - Multicolor thermal recording device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a multicolor thermal recording apparatus having a paper transport structure that does not cause color misregistration. [Structure] A capstan roll 8 is disposed so as to be rotatable in both forward and reverse directions, and in cooperation with a lower pressure roll 10 that abuts on the lower part of the capstan roll 8, an upper pressure roll 9 that nips a sheet P upstream of a printing unit and abuts on the upper part. Form P jointly with
Is clamped downstream of the printing unit. The ink ribbon r is movably stretched between the position of the tension roll 15 and the lower part of the paper transport restricting member 12, the right half peripheral surface of the platen roll 11, and the tip of the peeling shaft 17 above the paper transport restricting member 12. A paper transport path is formed. The capstan roll 8 conveys the paper P to the print start position based on the control of the number of steps for the stepping motor by the control unit, and further conveys it to the downstream side with the printing by the thermal head 19. In color overprinting, the paper P is conveyed backward by the same number of steps from the start of printing to the end of printing, and the paper P is correctly positioned at the print start position.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a multicolor thermal recording apparatus having a paper transport structure that does not cause color misregistration of recorded images.

[0002]

[Prior art]

 Conventionally, various forms of print output mechanisms are known. Among them, it is known that a color ink ribbon is used and color printing is performed by transferring ink to a sheet by a heating type print head. Usually, the print head is usually arranged on a carriage and prints while moving in the main scanning direction (the lateral direction of the printing operation). However, when performing color printing using a heat-generating print head, considering the printing speed, it is more efficient to configure the print head in a line so that the print dots are arranged in the main scanning direction by the maximum number of data. Target. Based on this idea, it has been proposed to use a so-called thermal head in which a heat-generating print head is a linear fixed head and to perform color printing using a relatively wide thermal transfer ink ribbon.

FIG. 4 is a schematic side cross-sectional view showing the structure in the vicinity of the printing portion of a multicolor printer having such a linear heat generation fixing head structure. As shown in the figure, the thermal head 1 is arranged so as to extend linearly in the vertical direction in the figure, and is in contact with the ink ribbon 2 and the lower surface (ink surface) of the ink ribbon 2 during printing. The paper P and the ink ribbon 2 are pressed against the platen roll 3 from above. On the other hand, at the time of non-printing or when the color is switched, it rises to the position shown by the broken line 1'in FIG. During printing, the paper P is conveyed while being pinched in front and back by a capstan roll 4 upstream and a capstan roll 5 downstream, which rotates in synchronism with the moving speed of the ink ribbon 2 (direction of arrow A). It moves to the right along with the ink ribbon 2 as indicated by arrow A in the figure. On the other hand, at the time of color switching, the capstan rolls 4 and 5 rotating in the reverse direction of the conveyance pull back the print start position. The ink ribbon 2 has the same width as the paper P, is supplied from the supply spool 6a, and is wound on the winding spool 6b. Normally, multicolored images are mixed with three primary colors of subtractive color mixture Y (yellow: yellow), M (magenta: red dye), and C (cyan: greenish blue) at various ratios to obtain various shades. It is expressed (actually, it is expressed in 4 colors with black added, but omitted in the following explanation). Therefore, on the ink ribbon for multicolor printing, the above three primary colors Y, M, and C are arranged side by side in the transport direction in a size corresponding to the area of one sheet of paper. Then, every time the printing with the color Y or the color M is completed, the paper P is pulled back to the print start position to print the next color M or the color C in an overlapping manner, and after the printing with the last color C is completed, it is kept as it is. Transported in the forward direction.

[0004]

[Problems to be solved by the device]

 By the way, the printing pitch of a thermal printer is usually about 8 dots per 1 mm (millimeter). Therefore, the size (diameter) of one print dot of the thermal head 1 is about 125 μm (micron), which is extremely small. On the other hand, if the capstan rolls 4 and 5 have different outer shapes in the configuration near the printing unit of the above-described multicolor printer, the paper feed amount of these two rolls will be different, and The paper P becomes loose or too tight between the rolls of the book. Therefore, there is a possibility that the paper position may be misaligned while the paper is repeatedly conveyed in the forward and reverse directions due to the overlapping printing of colors. When the misalignment occurs in the paper position as described above, one print dot is extremely small as described above, and it becomes impossible to superimpose colors on the correct dot position, causing color misregistration in the recorded image, which may be a corner or expensive multicolor image. There is a problem that an unsightly image is output even if it is printed.

In view of the above-mentioned conventional problems, an object of the present invention is to provide a multicolor thermal recording apparatus having a paper transport structure that does not cause color misregistration of recorded images.

[0006]

[Means for Solving the Problems]

 The structure of the thermal printer according to the present invention will be described below. The present invention is directed to an ink ribbon coated with an ink agent, a print head for selectively adhering the ink agent to a paper surface supplied through the ink ribbon in accordance with image information, and performing printing. Ink ribbon supply means for sequentially supplying a new surface of the ink ribbon on which the ink agent has been applied to the position where the print head is arranged, and a sheet which can be conveyed in both forward and reverse directions to the position where the print head is arranged. The paper transporting means, the ink ribbon supply means, the print head, and the ink ribbon feeding means for carrying out overlapping printing again while transporting the paper which has been once printed and transported in the forward direction by the paper transporting means in the reverse direction and then transports it again in the normal direction. The present invention is also applied to a multicolor thermosensitive recording apparatus provided with a control unit that controls a sheet conveying unit.

In the multi-color thermal recording apparatus of the present invention, the paper transporting means is provided with a single transport driving roller and the paper transporting roller which is provided so as to be in pressure contact with each of the transport driving rollers. The upstream side and the downstream side in the forward direction are each composed of two driven rollers that sandwich the sheet together with the above-mentioned conveyance drive roller.

[0008]

[Action]

 In this invention, a single conveyance drive roller nip a sheet in cooperation with two driven rollers and conveys the sheet in both forward and backward directions. As a result, the control means controls the forward and reverse rotation of only the single conveyance drive roller to always correctly set the paper pulled back for the color overprinting at the print start position.

[0009]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a recording sheet conveying mechanism of a multicolor thermal recording apparatus according to an embodiment. In the figure, the capstan roll 8 has a polyurethane coating on its outer peripheral surface so as to surely grip the sheet P fed from the left side to the right side in the figure indicated by the arrow B in the figure by a sheet feeding mechanism (not shown). It is arranged so that it can be driven to rotate in both forward (counterclockwise and counterclockwise) and reverse (clockwise) directions. An upper pressure roll 9 and a lower pressure roll 10 which are in contact with the upper and lower sides of the capstan roll 8 and hold the paper P in cooperation with the capstan roll 8 are provided. Further, a platen roll 11 is provided, which is slightly distant to the right from the capstan roll 8 and is parallel to the capstan roll 8 and rotates in synchronization with the capstan roll 8 at the same speed and in the same direction as the capstan roll 8. Further, a paper conveyance regulation member 12 is disposed between the capstan roll 8 and the platen roll 11 to properly guide the paper P carried into the printing section. The shape of each side surface of the sheet conveyance regulation member 12 is such that the cross section is recessed in a drum shape, and the both side surfaces are the circumferential surfaces of the capstan roll 8 and the platen roll 11 which are close to each other. Are arranged so as to cover approximately 1/3 of each.

A take-up spool 13 for taking up the printed ink ribbon r ′ and a supply spool 14 for supplying a new ink ribbon r are detachably arranged at slightly above and below the platen roll 11. . Further, a tension roll 15 is provided near the lower part of the paper transport regulation member 12 so as to apply an appropriate tension so that the ink ribbon r supplied from the supply spool 14 is not loosened or distorted. A transmissive paper edge detection sensor 16 for detecting the leading edge of the paper P carried into the printing portion is disposed substantially in the middle of the tension roll 15 and the lower pressure roll 10. In addition, a peeling shaft 17 for peeling the printed ink ribbon r ′ from the paper P discharged from the printing unit is provided in the vicinity of the upper portion of the paper conveyance regulation member 12. A reflection type ink position detection sensor 18 for detecting the ink arrangement of the ink ribbon r 1 or r ′ is provided near the upper portion of the peeling shaft 17.

On the right side surface of the platen roll 11, a thermal head 19 having the same width as the platen roll 11 is arranged. During printing, the thermal head 19 presses the ink ribbon r and the paper P in contact with the surface (ink surface) of the ink ribbon r against the platen roll 11 from the back surface of the ink ribbon r. On the other hand, during non-printing or color switching, it is configured to move to the position indicated by the broken line in the figure and separate from the ink ribbon r.

Next, the operation of paper conveyance at the time of printing by the recording paper conveyance mechanism having such a configuration will be described with reference to FIGS. 2 (a), (b), (c) and FIGS. 3 (a), (b), An explanation will be given using (c). Note that this operation is performed by a CPU (Central Processing Unit) of a control unit (not shown) using a control program stored in a ROM (Read Only Memory) or the like while using a RAM (Random Access Memory) or the like as a work area. It is realized by executing.

First, as shown in FIG. 2 (a), the paper P is fed to a paper feed roll (not shown) toward a paper carry-in port formed by the capstan roll 8 and the lower pressure roll 10 being in contact with each other. Thus, the sheet is fed from the left side to the right side in the drawing indicated by the arrow B.

Subsequently, as shown in FIG. 2B, the capstan roll 8 rotating in the forward direction indicated by the arrow C and the lower pressure roll 10 driven by the clockwise direction indicated by the arrow D are provided. , The paper P is sandwiched between the contact portions. Subsequently, the capstan roll 8 rotates in the forward transport direction, whereby the leading edge of the paper P reaches the paper edge detection sensor 16, and the paper edge detection sensor 16 detects the arrival of this paper P tip. In synchronization with the detection of the leading edge of the paper P by the paper edge detection sensor 16, a print start signal is output from the control unit, and step control is started for a stepping motor (not shown) driving the capstan roll 8. . Further, similarly, in response to the print start signal, the platen roll 11 starts rotating in the same direction as the capstan roll 8 indicated by the arrow E. Further, in synchronization with this, the take-up spool 13 starts rotating in the counterclockwise direction indicated by the arrow F, and the take-up operation based on this rotation causes the supply spool 14 to passively send the ink ribbon r. . Until this time, the thermal head 19 is separated from the peripheral surface of the platen roll 11 (actually, the back surface of the ink ribbon r).

The supply spool 14 is connected to a friction clutch (not shown), and back tension is applied to the supply spool 14 by the friction clutch. Therefore, back tension is applied from the supply spool 14 to the ink ribbon r pulled out from the supply spool 14 by the winding of the take-up spool 13. As a result, as shown in FIG. 7C, from the position of the tension roll 15 to the lower part of the paper transport regulation member 12, the right half peripheral surface of the platen roll 11, and the tip of the peeling shaft 17 above the paper transport regulation member 12. In the meantime, the ink ribbon r which is sent from the supply spool 14 (moved by being drawn by the take-up spool 13) and stretched without slack forms an appropriate paper transport path. The capstan roll 8 conveys the paper P to the print start position through the paper conveyance path based on the step number control of the stepping motor by the controller. In synchronization with the arrival time of the print start position of the paper P, the thermal head 19 moves in the circumferential direction of the platen roll 11 indicated by the arrow G, and presses the ink ribbon r onto the paper P from the back surface thereof.

Subsequently, as shown in FIG. 3A, the capstan roll 8, the platen roll 11 and the take-up spool 13 continue to rotate. Meanwhile, on the one hand, the paper P, along with the ink ribbon r, goes around the platen roll 11 halfway and is folded back to the upper part of the paper transport regulation member 12 to be transported toward the downstream side in the forward transport direction. Predetermined printing is performed on the surface P, and the printed ink ribbon r'is separated from the paper P at the tip of the peeling shaft 17 and wound up by the take-up spool 13, and the printed front portion P'of the paper P 1 is printed. Is sandwiched between the capstan roll 8 and the upper pressure roll 9 located on the downstream side in the forward direction of conveyance. Since the two upper pressure rolls 9 and the lower pressure rolls 10 are in contact with and follow the outer peripheral surface of the capstan roll 8, the feed amounts on the respective contact surfaces are equal. As a result, the paper P located between them, that is, located in the above-mentioned paper transport path, is sandwiched and transported at a constant speed in the front and rear. As a result, the paper P does not become loose and is not overly tensioned in the paper transport path. Therefore, a uniform printing tone is obtained, which enables clear printing.

In this way, when the printing of one color is completed and the paper P and the ink ribbon r ′ are separated by the peeling shaft 17, the capstan roll 8, the platen roll 11, and the take-up spool 13 respectively Stop rotation.

Next, as shown in FIG. 2B, the thermal head 19 is separated from the capstan roll 11, and the paper P is held only at one place of the mutual contact portion between the capstan roll 8 and the upper pressure roll 9. . Then, contrary to the case of printing, the capstan roll 8 rotates in the reverse transport direction indicated by the arrow H, and the upper pressure roll 9 and the lower pressure roll 10 are driven by this rotation, and the platen roll 11 further moves. In synchronization with the rotation of the capstan roll 8, the capstan roll 8 rotates in the same direction as the arrow I, and the supply spool 14 also rotates in the counterclockwise direction shown by the arrow K. Is conveyed in the reverse direction indicated by the arrow L.

In this reverse conveyance, the control unit reversely drives the stepping motor by the number of steps corresponding to the paper feed amount from the print start position shown in FIG. 2 (c) to the print end stop position shown in FIG. 3 (b). As shown in FIG. 7C, the rear portion of the paper P is reversely conveyed to the upstream side in the forward conveyance direction indicated by the arrow L ′, and the front portion of the paper P is localized at the print start position. . After this, the take-up spool 13 rotates in the counterclockwise direction indicated by the arrow M to wind the ink ribbon r in the forward transport direction, or the supply spool 14 rotates in the counterclockwise direction indicated by the arrow N. The ribbon r is wound in the reverse direction of conveyance, and during this time, the ink position detection sensor 18 detects the usable ink surface of the color to be printed next. Then, when the usable ink surface of the color to be printed next is detected, all the rotations are stopped, and the state returns to the state of FIG. 2 (c).

After that, the above-mentioned FIG. 2 (c), FIG. 3 (a), and (b) are repeated for each color to be overprinted, and when the printing of the last color is completed, the state of FIG. 3 (b) is changed. The paper P is discharged as it is to the downstream side in the forward transport direction.

As described above, since the transport roll is only a single capstan roll 8, the forward / reverse direction drive of the capstan roll 8 can be performed only by controlling the number of steps of the stepping motor. In both cases, the paper can be easily positioned correctly at the print start position.

In the above embodiment, the reflective ink position detection sensor and the transmissive paper edge detection sensor are used, but the invention is not limited to this, and the transmissive ink position detection sensor and the reflective ink edge detection sensor are used. Paper edge detection sensors may be used, or both may be reflective or both transmissive.

Further, although the platen roll 11 is provided as the print receiving base, the present invention is not limited to this, and a print receiving base fixed simply in a plate shape may be provided. Also, as described above, the capstan roll 8 may also function as the platen roll 11 without separately providing the print tray. By doing so, a more compact and inexpensive multicolor thermal recording apparatus can be realized.

[0024]

[Effect of device]

 As described in detail above, according to the present invention, the single conveying drive roller nip the sheet by the cooperation of the two driven rollers and conveys the sheet in both the forward and reverse directions. By controlling the forward / reverse rotation of the transport drive roller only, it is possible to always correctly orientate the paper pulled back for color overprinting at the print start position, and therefore print the next color at the correct dot position. It is possible to print a beautiful image without any color deviation. Further, since the single conveying drive roller is used, the sheet conveying mechanism can be downsized, and therefore, the multicolor thermal recording apparatus which is easy to handle and inexpensive can be realized.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a recording paper conveyance mechanism of a multicolor thermal recording apparatus according to an embodiment.

2A, 2B, and 2C are views (No. 1, No. 2, and No. 3) for explaining the operation of the sheet conveyance at the time of printing by the recording sheet conveyance mechanism.

3A, 3B, and 3C are views (No. 4, No. 5, and No. 6) for explaining the operation of the sheet conveyance at the time of printing by the recording sheet conveyance mechanism.

FIG. 4 is a schematic side cross-sectional view showing a configuration in the vicinity of a printing portion of a multicolor printer having a conventional linear heating fixed head structure.

[Explanation of symbols]

 8 Capstan Roll 9 Upper Pressure Roll 10 Lower Pressure Roll 11 Platen Roll 12 Paper Conveying Regulation Member 13 Take-up Spool 14 Supply Spool 15 Tension Roll 16 Paper Edge Detection Sensor 17 Peeling Shaft 18 Ink Position Detection Sensor 19 Thermal Head P Paper r, r ' ink ribbon

Claims (1)

[Scope of utility model registration request] 1. An ink ribbon coated with an ink agent,
A print head that selectively adheres the ink agent to a paper surface supplied through the ink ribbon in accordance with image information to perform printing, and the ink agent of the ink ribbon is placed at a position where the print head is disposed. Ink ribbon supply means for sequentially supplying the new coated surface, paper transport means for transporting the paper in both forward and reverse directions to the position where the print head is arranged, and once the printing is performed, the paper transport is performed. A control means for controlling the ink ribbon supplying means, the print head, and the paper transporting means for carrying out the overlapping printing again while transporting the paper transported in the forward direction by the means in the reverse direction and then again transporting it in the forward direction, In the multi-color thermal recording apparatus including a sheet feeding means, the sheet feeding means is provided with a single feeding driving roller, and the sheet feeding means is provided so as to be brought into pressure contact with each of the feeding driving rollers. The positive direction of the upstream side and multi-color thermal recording apparatus characterized in that it consists of two driven rollers for clamping together each of the transport driving roller the sheet downstream.