JPH0422656A - Paper skew correction method in line thermal printer and line thermal printer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to paper conveyance technology for printers.

In particular, the present invention relates to a technique for correcting skewed paper feeding in a line thermal printer.

[Prior Art] In a color printer equipped with a mechanism for printing multiple colors on the same paper surface by reciprocating the paper for multicolor printing, it is common for the paper to run diagonally with respect to the conveyance path. This may cause jamming or misalignment of colors.

Conventionally, a paper conveyance guide has been provided, and the paper has been devised to follow the guide so that it does not deviate from the conveyance path, thereby preventing the paper from skewing.

[Problems to be Solved by the Invention] The paper skew correction using the conveyance guide requires the paper moving force and
This is done by the resultant force of the drag force on the paper due to contact with the paper and the transport guide, but in line thermal printers, the head presses the entire width of the paper at once, so if the paper is wide, the pressure is strong and the transport guide It is difficult to correct the skew by just doing the following.

Furthermore, since the skew correction using the conveyance guide is performed during printing, it has the disadvantage of distorting the printed image. Particularly, when multiple colors are printed on the same sheet of paper, this distortion results in misalignment or incorrect colors.

SUMMARY OF THE INVENTION In order to solve this problem, it is an object of the present invention to correct the skew of paper before it is conveyed.

[Means for Solving the Problems] In order to achieve the above object, the skew correction method of the present invention includes forming a tangential portion on which the edge of the paper is to be brought into contact by bringing the platen and the line head into pressure contact, and then The present invention is characterized in that the sheet is fed while being pressed from the front and back toward the tangential portion, and after the entire edge of the sheet comes into contact with the tangential portion, the pressing state against the sheet is released.

In addition, the line thermal printer of the present invention includes a platen and a line head that form a tangential portion with which the edge of the paper is to be brought into contact, and presses the paper from the front and back toward the tangential portion formed by the platen and line head. After the entire edge of the paper is in contact with the front connection line,
The apparatus is characterized by comprising a paper supply roller that releases the pressing state against the paper.

[For production]

The principle of operation according to the present invention is shown in FIGS. 2(a) and (b).
(a) As shown in the figure, for example, two plates 11 and 12 are joined at an acute angle to form a tangential portion 13. These plates 11.
When paper P is pushed between 12 and 12, the edge P1 of paper P
It became like being caught between two plates 11 and 12,
(b) As shown in the figure, the gold edge of the paper edge P1 is at the tangent line 1.
When the force F that was pushing the paper P is released after the edges of the paper P come into contact with the two plates 11. Since it is in a temporarily fixed state due to the frictional force between it and 12, it stands still with the end P1 aligned with the tangential part 13.

According to the present invention, the platen and line head (the plate 11
．． 12) are pressed into contact with each other to form a tangential portion. By feeding the paper toward this tangential line, the paper comes to rest with its end aligned with the tangential line based on the above principle.

As a result, the posture of the sheet that is about to be skewed is corrected.

[Example] An example of a line thermal printer that implements the paper straightening method of the present invention will be described with reference to the drawings.

FIG. 1(a) is a schematic diagram of a line thermal printer of the present invention.

The paper supply roller is composed of a paper supply drive roller 2 and a paper supply pressure roller 3. Paper supply pressure roller 3
moves forward and backward toward the paper supply drive roller 2, presses the paper between it and the paper supply drive roller 2, and can release the paper.

The line thermal head 5 is installed perpendicularly across the paper conveyance path, and has a mechanism that can press against and release the platen 4.

An ink ribbon 7 is set between the line thermal head 5 and the platen 4.

Paper sensor 6 is located between paper supply drive roller 2 and line thermal head 5.

The paper 1 is pressed from both sides between a paper supply drive roller 2 and a paper supply pressure roller 3, and is conveyed to a platen 4 by receiving power from the paper supply drive roller 2.

Before the paper 1 reaches the platen 4, the line thermal head 5 and the ink ribbon 7 are brought into pressure contact with the platen 4.

The paper l receives power from the paper supply drive roller 2 and is conveyed until the paper sensor 6 detects its end. After being detected, the paper 1 passes through the paper sensor 6 and the line thermal head 5.
It is conveyed in the direction of the line thermal head 5 by a distance equal to the distance between them and the skew correction length.

The skew correction length is determined as follows from the expected skew angle θ (see FIG. 2(a)), the maximum value, and the paper width.

Skew correction length = paper width x sin (maximum value of skew angle) The skew angle is the angle formed by the line thermal head and the edge of the paper.

When the paper 1 is transported in the direction of the line thermal head 5 in this way, the paper 1 is transported as shown in FIG. 1(b).
Thermal head 5 and platen 4 via ink ribbon 7
The metal edge of the end portion 1a is aligned with the tangential portion 5a formed by pressure contact between the line thermal head 5 and the platen 4.

Subsequently, when the pressure on the paper 1 by the paper supply pressure roller 3 is released, the slack of the paper 1 is removed with reference to the end 1a that is in contact with the tangential part 5a formed by the thermal line head 5 and the platen 4. The end portion 1a stands still with respect to the line thermal head 5. As a result, the posture of the sheet 1 that tends to be skewed is corrected.

After this, the paper supply pressure roller 3 is pressed against the paper 1 again,
The line thermal head 5 is also opened to the platen 4, the paper 1 is moved to the printing position, and the thermal line head 5 is moved again.
Press to start printing.

[Effects of the Invention] According to the present invention, by bringing the edge of the paper into contact with the tangential portion formed by the platen and the line head, it is possible to correct the skew of the paper before it is conveyed.

[Brief explanation of drawings]

FIG. 1(a) is a schematic diagram of a line thermal printer that implements the paper straightening method of the present invention, and FIG. 1(b) is a perspective view of the main parts. FIGS. 2(a) and 2(b) are diagrams showing the effect of correcting the edges of the paper. 1... Paper 1a... Edge, paper supply drive roller, paper supply pressure roller, platen, line thermal head, tangential section, paper sensor, ink ribbon 8 applicants Seiko Epson Corporation

Claims (2)

[Claims] (1) After forming a tangential part on which the edge of the paper should come into contact by pressing the platen and the line head, feed the paper while being pressed from the front and back toward this tangential part, so that the edge of the paper A method for correcting paper skew in a line thermal printer, characterized in that the pressing state against the paper is released after the entire edge of the paper comes into contact with the tangential part. (2) A platen and a line head that form a tangential part on which the edge of the paper should come into contact, and a paper being pressed from both sides toward the tangential part formed by the platen and line head, and the paper A line thermal printer comprising: a paper supply roller that releases the pressing state against the paper after the entire edge of the paper comes into contact with the tangential portion.