JPH09110233A - Paper sheet carrying mechanism of printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper sheet carrying mechanism of a printer by which image quality after being printed can be improved by eliminating nonuniformity of a surface shape and thermal transfer of a printing paper sheet while maintaining carrying force of the printing paper sheet. SOLUTION: A paper sheet carrying mechanism of a printer is provided with a driving roller 5 driven in turn to carry a printing paper sheet 1, a pinch roller 25 which is turnably juxtaposed with the driving roller 5 and sandwiches the printing paper sheet 1 with the driving roller 5 and a roller structure body 20 to make pressure contact force to bring the pinch roller 25 into pressure contact with the driving roller 5 act in the axial direction of the pinch roller 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper transport mechanism of a printer suitable for use in a thermal transfer color printer or the like.

[0002]

2. Description of the Related Art A conventional paper transfer mechanism for a thermal transfer color printer is shown in FIG. 4, which will be described below. In FIG. 4, the printing paper 1 having a specified size and the ink ribbon 2 are pressed against each other by the thermal head 3 and the platen roller 4, and the heating element on the thermal head 3 generates heat to correspond to the print data on the ink ribbon 2. The part is melted, and the ink is transferred to the paper 1.

Further, the sheet 1 is sandwiched between the minute protrusion roller 5 and a plurality of small rollers 6, and the minute protrusion roller 5 rotates to move away from the thermal head 3 (m in FIG. 4).
Direction). That is, from the start to the end of printing, the paper 1 is not released while being sandwiched between the minute protrusion roller 5 and each small roller 6. At the end of printing, the pressure contact force between the small rollers 6 and the minute protrusion rollers 5 is released by a predetermined paper release mechanism, and the paper 1 is released. Also,
The ink ribbon 2 is wound up by a ribbon winding roller (not shown) driven by a DC motor.

Next, the detailed structure of each small roller 6 and the minute projection roller 5 will be described with reference to FIGS. In both figures, each small roller 6 is a curved notch of a plurality of pinch roller levers 11 that are loosely fitted to a pinch roller shaft 10 that is juxtaposed with the minute protrusion roller 5 at a predetermined interval. 11a, and the protrusions 6b provided at both ends of the small roller 6 are sandwiched by the inverted U-shaped notches 11b of the pinch roller lever 11 so as to be held at a position in contact with the minute protrusion roller 5. ing. Further, the pinch roller shaft 10 on which the pinch roller levers 11 are positioned is screwed to the side corresponding to the bottom side of a plurality of pinch roller pressure contact springs 12 formed in a substantially isosceles triangular shape. The side corresponding to the apex of 12 is in contact with the center of the tip of each pinch roller lever 11. The pinch roller shaft 10 can be rotated in the p direction or q direction in FIG. 4 by a cam mechanism (not shown). An ink ribbon position sensor 15 detects the position of the ink ribbon.

At the time of printing, the pinch roller shaft 10 rotates in the p direction by a predetermined angle by the cam mechanism, and each pinch roller pressure contact spring 12 urges the pinch roller lever 11 toward each small roller 6. As a result, the protrusions 6b of the small rollers 6 sandwiched between the cutout portions 11b are pressed, and the small rollers 6 are pushed by the small protrusion rollers 5.
Is pressed against. Then, at the start of printing, the paper 1 is
The tip side is sandwiched between each small roller 6 and the minute protrusion roller 5, and the minute protrusions of the minute protrusion roller 5 are applied to the back surface 1B of the sheet 1 by the pressing force received from each small roller 6 as the minute protrusion roller 5 rotates. While being pressed into a state of biting, it is conveyed in the direction m in FIG. 4, and the ink on the ink ribbon 2 is thermally transferred to the printing surface 1A of the paper 1 by the heating element on the thermal head 3. Also, the printed sheet 1
When releasing, the pinch roller shaft 10 rotates in the q direction and returns to the state before printing. That is, the pressure contact force of each pinch roller pressure contact spring 12 against the small roller 6 is released, and the sheet 1 is released.

[0006]

However, in the paper transport mechanism of this prior art printer, in order to reliably transport the paper, a certain pressure contact force is applied to each small roller by the pinch roller pressure contact spring, and each small roller is pressed. Since the roller directly presses the paper against the micro-projection roller, there occurs a shape deformation that causes a difference in the indentation of the printing surface of the paper between the portion pressed by each small roller and the portion not pressed. As a result, if a dent difference occurs on the printing surface of the paper, unevenness such as density or color difference occurs in the thermal transfer of ink between the portion of the paper that is pressed against each small roller and the portion that is not pressed against it. There was a problem that the image quality afterwards deteriorated.

The present invention has been made to solve this problem, and improves the image quality after printing by eliminating the unevenness of the surface shape and thermal transfer of the printing paper while maintaining the conveying force of the printing paper. An object of the present invention is to provide a paper transport mechanism of a printer that can perform the above.

[0008]

In order to solve the above problems, in the paper transport mechanism of the printer of the present invention, in claim 1, a drive roller which is rotationally driven for transporting print paper, and the drive roller. A pinch roller that is rotatably arranged side by side and that sandwiches the print sheet with the drive roller, and a pressure contact force that presses the pinch roller against the drive roller, acts uniformly over the axial direction of the pinch roller. And a roller structure that allows it. As a result, when the printing paper is sandwiched between the pinch rollers and conveyed along with the rotation of the drive roller, the pressure contact force that is uniformized in the axial direction of the pinch rollers is sequentially conveyed through the pinch rollers. It can also be applied to paper.

[0009] In the second aspect, the first aspect has the following features.
The roller structure includes a shaft arranged in parallel with the pinch roller at a predetermined distance, and a plurality of small rollers distributed in the axial direction of the pinch roller and rotatably provided on the shaft. A pressure contact member for urging the pinch rollers against the pinch rollers, the pressure contact members exerting the same or different pressure contact forces on the respective small rollers to the pinch roller. It is one that urges. As a result, the small rollers distributed in the axial direction of the pinch roller are urged to the pinch roller by the pressure contact members with the same or different pressure contact forces, so that this pinch roller, this pinch roller and the drive roller. The printing paper sandwiched by and can be pressed against the drive roller while exerting a pressing force distributed in the axial direction by each small roller.

In the third aspect, in addition to the third aspect,
The shaft is provided with a pair of brackets rotatably with the small rollers arranged therebetween, and the pinch roller is provided between the small rollers and the drive roller by the pair of brackets. It is rotatably positioned. As a result, the pinch roller is arranged between each small roller and the drive roller by the pair of brackets provided on the shaft. Therefore, the pinch roller can be rotatably brought into contact with the drive roller with a simple structure. You can

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A paper transport mechanism of a printer which is an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing a paper transport mechanism of a printer according to an embodiment of the present invention, FIG. 2 is a perspective view showing a detailed configuration of a paper transport mechanism of a printer according to the embodiment of the present invention, and FIG. FIG. 6 is a schematic diagram showing the operation of the paper transport mechanism of the printer in the embodiment. 1 and 2 according to the embodiment of the present invention, the same reference numerals as those in FIGS. 4 and 5 of the prior art indicate the same configurations, and thus the description thereof will be omitted.

1 and 2, the present embodiment is similar to that shown in FIGS. 4 and 5 of the prior art, and includes a plurality of pinch roller levers 11 rotatably fitted to a pinch roller shaft 10. A small roller 6 held at the tip of each pinch roller lever 11, and a pinch roller pressure contact spring 12 for urging each small roller 6 toward the minute protrusion roller 5 side.
The structure composed of and is used as the press roller structure 20, and the pinch roller 25 is disposed between the press roller structure 20 and the minute projection roller 5.

The pinch roller 25 is a single roller extending so as to be juxtaposed in parallel with the minute protrusion roller 5 and has the same diameter as or smaller than that of the minute protrusion roller 5. In order to make the print area of the micro-projection roller 5 as large as possible with respect to the paper size, each small roller 6 of the press roller structure 20 is designed to reduce the distance between the contact between the micro-projection roller 5 and the pinch roller 25 and the thermal head heating element. Can't be too big. The pinch roller 25 is rotatably supported by fitting the protrusions 25a and 25a provided at both ends thereof into the through holes 30a and 31a of the pair of brackets 30 and 31, respectively. Each of the brats 30 and 31 is rotatably fitted on the pinch roller shaft 10 of the press roller structure 20, and the pinch roller 25 is arranged between each small roller 6 and the minute protrusion roller 5. , This minute protrusion roller 5
The shape is determined so as to contact the outer peripheral surface 5A from above. The pinch roller 25 has high rigidity,
For example, a cylindrical cored bar made of iron and externally fitted with a tube made of elastic rubber or resin is used.

The pinch roller lever 11 constituting the press roller structure 20 is pinched between the pair of brackets 30 and 31 with a predetermined space (for example, the same space) between them in the axial direction of the pinch roller 25. The small roller 6 is rotatably fitted to the roller shaft 10 and is held at a position in contact with the pinch roller 25. Further, each pinch roller pressure contact spring 12 screwed to the pinch roller 10 is provided with a pinch roller shaft 10 when the pinch roller shaft 10 is rotated a predetermined angle in the p direction in FIG.
Each small roller 6 is pinched by the contact pressure F (spring force).
The material, the shape, the thickness, etc. are determined so as to be biased to No. 5. Thereby, when the pinch roller shaft 10 is rotated in the p direction, the pinch roller pressing springs 12 press the small rollers 6 with the pressing force F.
5, the pinch roller 25 is in a state where it receives uniform pressure contact forces F, F, F, ... In the axial direction from the small rollers 6 distributed with a predetermined interval. Become. Then, the pinch roller 25 is pressed against the minute projection roller 5 by rotating the pair of brackets 30 and 31 about the shaft 10 by the distributed pressing force F, F, F ,.

When printing, the pinch roller shaft 10 rotates in the p direction by a predetermined angle by the cam mechanism, and the pinch roller pressure springs 12 urge the pinch roller levers 11 toward the small rollers 6. As a result, the protrusions 6b of the small rollers 6 sandwiched between the notches 11b are pressed, and as shown in FIG. 3A, the small rollers 6 are pressed against the pinch roller 25 by the pressure contact forces F, F,
Since F, ... Are applied, the pinch roller 25 causes the contact pressure force F, which is evenly distributed over the entire axial direction,
It is pressed against the micro-projection roller 5 while holding F, F, .... At this time, when the pinch roller 25 receives the pressure contact forces F, F, F, ... In the axial direction, as shown in FIG. 3B, the pinch roller shaft 10 also receives the pressure contact forces F, F, F ,.
.. acts to cause the pinch roller shaft 10, the pinch roller 25, and the minute projection roller 5 to bend. Further, this force also causes the minute protrusion roller 5 to bend. At this time, since the diameter of the pinch roller 25 is equal to or smaller than the diameter of the minute protrusion roller 5,
Since the pinch roller 25 and the fine protrusion roller 5 are in close contact with each other and bend, the pressure contact forces F, F, F, ... Are distributed evenly in the axial direction between the pinch roller 25 and the fine protrusion roller 5.
.. can be operated.

Thus, at the start of printing, the paper 1
Has a pinch roller 25 and a micro-projection roller 5 at its tip side.
The pinch roller 25 is sandwiched between the small protrusion rollers 5 and is rotated in the axial direction of the pinch roller 25 by the pressure contact forces F, F, F, ... Pressure contact forces F, F, F that are made uniform over the entire area of
... so that the minute protrusions of the minute protrusion roller 5 bite into the entire surface of the back surface 1B of the sheet 1, that is, the sheet 1 is brought into a pressure contact state without being partially deformed. While being conveyed in the m direction, the ink on the ink ribbon 2 is thermally transferred to the printing surface 1A of the paper 1 by the heating element on the thermal head 3. As a result, it is possible to eliminate the unevenness of the surface shape, which is accompanied by the partial shape deformation of the paper 1, so that it is possible to prevent the occurrence of unevenness in the thermal transfer of the ink, such as the difference in density and color, and to improve the image quality after printing. Can be improved.

The press roller structure 2 in this embodiment is used.
0 is not limited to this, but the pinch roller 25
Of the pressure contact force F, F, F, F
Any structure may be used as long as it can ...

Further, in this embodiment, by changing the material, shape and thickness of each pinch roller pressure contact spring 12, the pressure contact forces for urging each small roller against the pinch roller 25 may be the same or different from each other. Then, pinch roller 2
It is also possible to change the pressure contact force of 5 to the minute protrusion roller 5 according to the conveyance force of the sheet 1. Further, the number of pinch roller levers 11 (small rollers 6) rotatably provided on the pinch roller shaft 10 is not limited to this, and may be changed depending on the lengths of the pinch roller 25 and the minute projection roller 5. , Is increased or decreased.

[0019]

As described above, according to the paper transporting mechanism of the printer of the present invention, in claim 1, when the printing paper is sandwiched between the pinch roller and transported as the drive roller rotates, the axis line of the pinch roller is conveyed. The pressure contact force that has been made uniform in all directions can also be applied to the printing paper that is sequentially conveyed via the pinch rollers. As a result, it is possible to eliminate the unevenness of the surface shape, which is accompanied by the partial shape deformation of the printing paper, without reducing the paper transporting force, so that the occurrence of unevenness such as density or color difference in the thermal transfer of ink. It can be prevented and the image quality after printing can be improved.

In addition to the effect of the first aspect, the small rollers distributed in the axial direction of the pinch roller are attached to the pinch roller by the pressure contact members with the same or different pressure contact forces. Because it is energized, with this pinch roller,
The printing paper sandwiched between the pinch roller and the driving roller can be pressed against the driving roller while exerting a pressing force distributed in the axial direction by each small roller. As a result, it is possible to eliminate the unevenness of the surface shape, which is accompanied by the partial shape deformation of the printing paper, without reducing the paper transporting force, so that the occurrence of unevenness such as density or color difference in the thermal transfer of ink. It can be prevented and the image quality after printing can be improved.

Further, in addition to the effect of claim 2, in claim 3, the pinch roller is arranged between each small roller and the driving roller by a pair of brackets provided on the shaft, which is simple. With the structure, the pinch roller can be rotatably brought into contact with the drive roller.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a paper transport mechanism of a printer according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a detailed configuration of a paper transport mechanism of the printer according to the embodiment of the present invention.

3A and 3B are schematic diagrams for explaining the operation of the paper transport mechanism of the printer according to the embodiment of the present invention.

FIG. 4 is a schematic view showing a paper transport mechanism of a conventional printer.

FIG. 5 is a perspective view showing a detailed configuration of a paper transport mechanism of a conventional printer.

[Explanation of symbols]

 1 Printing Paper 5 Micro Protrusion Roller (Drive Roller) 20 Press Roller Structure (Roller Structure) 25 Pinch Roller

Claims (3)

[Claims] 1. A drive roller that is rotatably driven to convey a print sheet; a pinch roller that is rotatably juxtaposed to the drive roller to sandwich the print sheet by the drive roller; and a pinch roller. A paper transport mechanism for a printer, comprising: a roller structure that applies a pressure contact force that presses the drive roller to the drive roller uniformly in the axial direction of the pinch roller. 2. The roller structure is rotatably provided on a shaft arranged in parallel with the pinch roller at a predetermined distance from each other, and distributed in the axial direction of the pinch roller so as to be rotatable on the shaft. The pinch roller is configured by a plurality of small rollers and a pressure contact member that urges each of the small rollers to the pinch roller, and the pressure contact member applies the same or different pressure contact force to each of the small rollers. 2. The paper transport mechanism for a printer according to claim 1, wherein the paper transport mechanism is biased to. 3. The shaft is provided with a pair of brackets rotatably with the small rollers interposed therebetween, and the pinch roller is driven by the pair of brackets and the small rollers. 3. The paper transport mechanism for a printer according to claim 2, wherein the paper transport mechanism is rotatably positioned between the roller and the roller.