JPH079652Y2 - Thermal printer - Google Patents

Description

[Detailed Description of Device] a. TECHNICAL FIELD The present invention relates to a thermal printer having a line head.

B. Conventional technology When continuously recording on continuous recording paper with a thermal printer that uses a thermal line head, the thermal printer uses a heating head to heat the local area of the thermal paper to develop color, so when the print density is high, the printer head The paper passing underneath has a considerable temperature, and as the temperature rises, the paper softens to some extent and undergoes thermal expansion. For this reason, when the print pattern is uneven and there is a part with high color density in the thermal printer using the line head, the printing paper undergoes uneven thermal expansion and the tensile force acting on the paper becomes uneven in the paper width direction. Since the heat-expanded part of the paper is somewhat softened and is more easily stretched by the tension than the other parts, the paper passing through the printer head tends to be attracted to the side with less elongation. In some cases, the paper meanders, print misalignment occurs, and wrinkles sometimes occur to cause remarkable print defects. Conventionally, in order to prevent the meandering of the paper, the line head is moved up and down each time printing is performed to return the recording paper to the original position, or the position of the side edge of the paper is detected to shift the position of the recording paper. In this case, a paper edge position control device for correcting the position of the recording paper is used, but these methods have a problem that the device is expensive and the device becomes large. There is also a method to feed the paper by engaging a pin such as a roll with a pin with the paper hole of the paper to forcibly position the paper so that it does not meander, but if the meandering force is large, the area around the paper hole is damaged. The problem that occurs occurs.

C. Problems to be Solved by the Invention The present invention is intended to solve such troubles caused by meandering of the paper.

D. Means for solving the problem In the printer, the paper meanders to the left and right to some extent, but by design, the running position of the paper is assumed to be a direction perpendicular to the running direction of the paper. It is called the reference traveling position. The present invention is intended to suppress the width of the meandering, and in a thermal printer equipped with a line head, brakes the feeding of the paper to the line head on the paper feed side of the line head, and The brake shoe that applies braking friction by sliding the brake on the paper without rotating it over the entire width of the paper.The brake shoe acts on the paper surface from the contact line with the paper at the center of the width of the paper at the reference traveling position of the paper. The structure is swingably supported by an axis perpendicular to the.

E. Action The brake shoe exerts a braking force over the entire width of the paper.When the paper meanders and shifts to one side, the brake shoe can swing to the left and right, so it moves to the same side of the paper, and the swing center Since it is located on the side of the paper that enters the brake part, the center of the frictional force in the paper transport direction over the entire width of the paper shifts from the swing center to one side and a restoring moment is generated toward the brake original position. This restoring moment causes the paper to receive a force that returns it to the correct original position. This action suppresses the meandering of the paper.

F. Embodiment The drawings show an embodiment of the present invention. In FIG. 1, P is a continuous thermal paper, which is transported to the right (arrow) in the figure. 1
Is a thermal line head, and 2 is a brake shoe.
The brake shoe 2 is not a roller but only slides on a sheet and does not rotate as the sheet is fed.

The brake shoe 2 is swingably held in a horizontal plane (paper surface in the drawing) by a vertical shaft 3 at a position apart from the center in the paper width direction and on the paper input side (left side in the drawing). As shown in FIG. 2, under the thermal paper P, the heating element array of the thermal line head is arranged.
There is a platen roller 4 under 1d, and the thermal line head 1 is pressed against the platen roller 4 by a spring 5. Similarly, below the brake shoe 2 is a drive roller 6, which is driven by a spring 5 '.
Being pressed against. There is a pair of pull-out rollers 7 on the paper output side (right side in the figure) of the thermal line head 1, and the paper P is sandwiched and pulled out to the right. Instead of using the pull-out roller 7, the platen roller 4 may be driven in the paper feeding direction to pull out the paper. The platen roller 4, the drive roller 6, and the pull-out roller 7 are connected and driven by a timing belt.

As shown in FIG. 3, guide pins 8 are erected on the portions of the brake shoe 2 that project from the width of the sheet,
The guide pin is loosely connected to the guide hole 9 and regulates the swing range of the brake shoe. This is because it is inconvenient if the brake shoes swing too much when the paper is first passed or when the printer is moved.

With the above configuration, it is assumed that the sheet P meanders as shown in FIG. 4 and shifts by Δ to the right in the figure. There is no lateral slip between the paper and the brake shoe 2, and the brake shoe can be swung about the shaft 3 so that the paper swings as shown in FIG. The center of the frictional force F moves by Δ from the position of the regular center of the paper. For this reason, a restoring moment of FΔ only in the direction opposite to the arrow in the figure is generated in the brake shoe 2, and acts to return the sheet to the normal position.

Note that in the above-described embodiment, the thermal line head 1, like the brake shoe 2, is held so as to be swingable in the horizontal plane by the vertical axis 10 at a position apart from the center of the width of the brake shoe 2 toward the sheet input side, so that the sheet P is made to meander. Following this, it moves to the left and right to eliminate the lateral deviation of the print pattern and to give a restoring force to the meandering of the paper P, which further suppresses the meandering by the brake.

G. Effect As described above, the thermal printer of the present invention applies a braking force to the continuous paper to the feeding direction on the paper input side of the thermal line head, and a brake that applies this braking force is applied to the surface of the thermal paper. Since the structure is simple in that it is swingable around a vertical axis, the brake shoes move left and right following the meandering of the thermal paper, causing a wrinkle that is generated by trying to forcibly prevent the meandering of the thermal paper. In the case of a paper having a hole or a hole, troubles such as print defects and paper jam caused by the crease or crush of the hole can be avoided. On the other hand, the meandering of the thermal paper itself is suppressed by generating the restoring force to the regular position. In particular, since the braking means is not a roller that is in rolling contact with the sheet but merely a brake shoe that slides in contact with the sheet, the ability to recover from meandering is ensured. If the braking means is a roller, the roller rotates together with the sheet feeding, and when the sheet is biased to one side due to the meandering of the sheet, the roller is also biased to that side, but at that time, the roller rotation is slightly less than the direction perpendicular to the sheet feeding direction. Since the paper is tilted, the tilted roller comes into contact with the paper, and a motion component is generated at the contact portion of the roller surface in the direction of the paper's deviation at right angles to the paper feeding direction, which promotes the meandering of the paper. When the brake shoes are brought into sliding contact with each other, the action of promoting such meandering is not included at all.

[Brief description of drawings]

FIG. 1 is a top view of essential parts of a printer according to an embodiment of the present invention, and FIG.
Similarly, FIG. 3 is a side view of a main part, FIG. 3 is a front view of a side part of a brake shoe, and FIG. P ... Paper (thermal paper), 1 ... Thermal line head,
2 ... Brake shoe, 3 ... vertical axis holding the brake shoe, 4 ... platen roller, 5,5 '... spring, 6
...... Brake roller.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Kazuhito Murata Inventor, Kazuhito Murata 4-3-1, Jokoji, Amagasaki City, Hyogo Kanzaki Paper Mill Co., Ltd. 29, Machi Sato Manufacturing Co., Ltd. (72) Inventor, Yasushi Tanaka 29, Nishinokyo Minamitsuimachi, Nakagyo-ku, Kyoto City, Kyoto Prefecture (56) Sato Manufacturing Co., Ltd. (56) Reference JP-A-60-73874 (JP, A) Kai 61-56057 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A thermal line head is provided, and a braking means that acts on the entire width of the sheet is provided on the sheet entry side of the sheet drawn through the thermal line head into the thermal line head. The brake shoe is configured so that it can be slidably contacted with the brake shoe without rotating, and the brake shoe is centered on an axis perpendicular to the paper surface at the paper width center position of the paper at the reference traveling position of the paper on the paper input side to the brake shoe. A thermal printer that holds the swingable.