JPH0318191Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to a pressure mechanism that equalizes the head pressure of a thermal printer.

(b) Background of the technology Thermal printers use tantalum nitride (TaN), nickel chrome (Ni.
The thermal head, which has a heat-generating section in which tiny dot-shaped heat-generating elements made of thin-film resistors such as Cr) are arranged in a row, is pressed against thermal paper, and in this state a signal voltage is applied to select only a specific heat-generating element. This is a printer that prints characters or graphics consisting of a combination of multiple dots by generating heat.

The thermal head consists of a heat generating section with heat generating elements lined up in a row and a number of semiconductor ICs that drive the heat generating section.The thermal head is mounted on a thermal head bracket and pressed against the capstan roller by a leaf spring. The roller is used as a printing base to print on the thermal paper that is hung on the roller.

The present invention relates to a pressurizing mechanism that keeps the rotating shaft of the capstan roller and the heat generating part of the thermal head completely parallel to each other.

(c) Prior art and problems Figure 1 shows the printing mechanism of a thermal printer. That is, a capstan roller 2 that feeds the thermal paper 1 wound into a roll is connected to a large pulley 3, and is connected to a motor 5 via a small pulley 4.
It is driven by.

Next, as shown in FIG. 2A, the thermal head 6 consists of an insulating substrate 8 with a heat generating part 7 in which a number of heat generating elements are arranged in a row centered on a central part 7, and semiconductor ICs for driving the heat generating part 7 mounted on both sides. , the IC mounting part is covered with a cover 9 and is inserted into the thermal head bracket 10 shown in FIG. 2B, and as shown in FIG.
2, a structure is adopted in which pressure is applied to the capstan roller 2.

That is, the thermal paper 1 wound into a roll passes under the capstan roller 2 and is fed by the capstan roller 2 while being printed while being pressed from below by the thermal head 6.

Figure 3 shows the thermal head bracket 10 with the capstan roller 2 and thermal head 6 mounted in this case, and the leaf spring 11 fixed thereto.
Figure A is a front view and Figure B is a side view.

In order for the thermal paper 1 to be printed with the same printing density over the entire area of each row, the rotating shaft 13 of the capstan roller 2 and the thermal head 6 must be held completely parallel. It is.

Therefore, as shown in FIG. 4, two leaf springs 11 and 12 are attached to the thermal head bracket 10 so that even if the capstan roller 2 is tilted from the horizontal position, the thermal head 6 will follow this and maintain a parallel state. They were placed near both ends.

However, if the width of the thermal head 6 is short and the distance between the leaf springs 11 and 12 is short, even if the capstan roller 2 is slightly tilted, the leaf springs 11 and 12 will be twisted. There was a problem in that the operation of the head was insufficient and the head pressure became uniform, resulting in uneven printing.

(d) Purpose of the invention The purpose of the present invention is to provide a pressurizing mechanism that can follow the inclination of the capstan roller and provide a uniform head regardless of the width of the thermal head.

(e) Structure of the invention The purpose of this invention is to press a thermal head bracket equipped with a thermal head having a heat generating section in which a plurality of heat generating elements are arranged in a line against a capstan roller with a leaf spring, while pressing the heat generating section of the thermal head. In a thermal printer that selectively generates heat and prints on thermal paper fed by the capstan roller, a plurality of protrusions are provided on the back surface of the thermal head bracket, and a leaf spring is connected to the thermal head bracket through the protrusions. A thermal head characterized in that when the capstan roller is brought into point contact and the capstan roller is tilted, the horizontal state of the leaf springs does not change and only the relative heights of the leaf springs change to prevent the occurrence of twisting of the leaf springs. This is achieved by a pressurizing mechanism.

(f) Embodiment The present invention eliminates the occurrence of twisting by changing the conventional surface contact between the thermal head bracket 10 to which the thermal head 6 is mounted and the plate springs 11 and 12 to point contact. This allows uniform pressure to be applied to the capstan roller 2 even when the width of the thermal head 6 is narrow.

FIG. 5 shows the relationship between the thermal head bracket 14 and the leaf springs 11 and 12 according to the present invention. The thermal head bracket 14 is provided with a plurality of projections 15 (in this case two at a time) and brought into point contact.
By applying pressure through this contact point, the generation of torsional force is eliminated.

That is, in the case of the conventional structure shown in FIG.
1 and 12 themselves have to be tilted, and at this time twisting occurs, resulting in incomplete tracking of the capstan roller 2.

However, in the case of point contact as shown in FIG. Therefore, tracking is performed ideally.

(g) Effect of the invention This invention is based on the roller shaft 13 of the capstan roller 2.
The conventional structure in which pressure is applied using two leaf springs 11 and 12 has a problem in that uneven printing occurs when the thermal head 6 is out of position, especially when the length of the thermal head 6 is short. By employing a structure in which the bracket 14 is in point contact with the leaf springs 11 and 12, uniform pressure can be applied and uneven printing can be eliminated.

[Brief explanation of the drawing]

Figure 1 is a perspective view explaining the configuration of a thermal printer, Figure 2 is a perspective view of a thermal head and a thermal head bracket to which it is attached, and Figure 3 is an explanation of the pressure mechanism between the capstan roller and the thermal head. In the figures, Figure A is a front view, Figure B is a side view, Figure 4 is a front view A and side view B showing a state in which the roller axis of the capstan roller is tilted, and Figure 5 is an embodiment of the present invention. Figure A is a front view, and Figure B is a side view. In the figure, 2 is a capstan roller, 6 is a thermal head, 7 is a heat generating part, 10 and 14 are thermal head brackets, 11 and 12 are leaf springs, 13 is a roller shaft, and 15 is a protrusion.

Claims (1)

[Scope of utility model registration request] A thermal head bracket equipped with a thermal head having a heat generating section in which a plurality of heat generating elements are arranged in a row is pressed against the capstan roller by a leaf spring to selectively generate heat in the heat generating section of the thermal head. In a thermal printer that prints on thermal paper that is fed by a stan roller, a plurality of protrusions are provided on the back surface of the thermal head bracket, and the inclination of the capstan roller is adjusted by making point contact with a leaf spring through the protrusions. 1. A pressurizing mechanism for a thermal head, characterized in that it is configured to prevent the occurrence of torsion of the leaf springs by changing only their relative heights without changing the horizontal state of the leaf springs.