JPH03108564A - Thermal printer - Google Patents

Abstract

PURPOSE:To prevent breakdown of a thermal head caused by an electrocorrosion and electrostatic noise by a method wherein a printer mounting part is composed of at least two layers, the upper layer to which a paper guide is abutted is made of a conductive member, the lower layer is made of an insulating member, and the conductive member as the upper layer is grounded. CONSTITUTION:A printer fixing plate 6 has a three-layer structure. The upper layer is made of a conductive earth plate 6a, the intermediate layer is made of an insulating sheet 6b, and the lower layer is made of a metallic substrate 6c. On the earth plate 6a as the upper layer, a paper guide 3 is fixed with a bis, and the earth plate 6a and the paper guide 3 are electrically connected with each other. The earth plate 6a is grounded through a surge absorber 9. A high-voltage electrostatic noise discharged from a human body to the conductive member 6a as the upper layer of the printer mounting part and the paper guide 3 at the setting of printing paper or the like flows into the ground through the surge absorber 9, therefore never being secondarily discharged from the paper guide 3 to a thermal head 1. In this manner, breakdown of the thermal head caused by an electrocorrosion and an electrostatic noise is prevented from occurring.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thermal printer that prints using a thermal head. The part has at least a two-layer structure,
The upper layer in direct contact with the paper guide is made of a conductive material, and the lower layer is made of an insulating material. By grounding the upper conductive material through a surge absorber, surges can be prevented when high voltages due to static electricity noise are not generated. By flowing current to the ground through the absorber, high voltage due to static electricity is prevented from discharging to the thermal head and destroying it. Under normal conditions, the surge absorber and the underlying insulating material prevent the thermal head from being damaged. By electrically floating the paper and the paper guide, electrolytic corrosion of the thermal head due to movement of ions contained in the thermal paper is prevented.

[Prior Art] As shown in FIG. 2, a print head (thermal head) l of a thermal printer includes a protective film layer 1a, an electrode layer 1b,
Although it has a resistor layer 1c and a substrate 1d, it has a protective film layer 1a.
If there are pinholes in the electrode layer 1b of the thermal head 1, electrolytic corrosion has occurred in the electrode layer 1b of the thermal head 1. That is, in the mounting state shown in FIG. 3, moisture and Na contained in the thermal paper 2 are
Thermal head 1→ through ions, K ions, etc.
Thermal paper 2 → paper guide 3 → conductive printer fixing plate 4-・
Leakage current flows in the ground (GND) path, and in this process, for example, if the electrode layer 1b is made of aluminum, the electrode layer 1b corrodes due to the electrochemical reaction AN +30H-→AN(OH)3. It had been electrolytically eroded.

Therefore, conventionally, as shown in FIG. 4, by using a non-conductive printer fixing plate 5 as the printer fixing plate, the thermal head 1, the thermal paper 2, and the paper guide 3 are electrically floated, and the leakage current is reduced. This prevents the electrode layer 1b from being destroyed by electrolytic corrosion.

[Problem to be solved by the invention] However, when inserting printing paper such as thermal paper 2, high voltage static electricity accumulated in the human body is discharged to the paper guide 3, and this paper guide 3 becomes electrically floating. Due to the condition, paper guide 3
Since the static electricity discharged to the thermal head 1 is secondary discharged to the thermal head 1, a new problem has arisen in that the thermal head 1 is destroyed. The reason why it is not possible to prevent the destruction of both thermal heads 1 at the same time is thought to be due to the fact that the printer fixing plate is made of the same material.

It is clear that if the configuration of the printer fixing plate is improved, it will be possible to prevent both electrolytic corrosion and destruction of the thermal head due to electrostatic noise at the same time.

The problem of this invention is to devise the structure of the printer fixing plate,
To simultaneously prevent damage to a thermal head due to electrolytic corrosion and electrostatic noise.

"Means for Solving the Problems" The means of the present invention are as follows.9 This apparatus is a thermal printer that prints using a thermal head, and has the following means.

■Printer mounting section - This printer mounting section has a conductive member layered on the upper layer and an insulating member layered on the lower layer.

0 Paper Guide - This paper guide is placed on top of the upper layer conductive member 9 ■ Surge absorber means: This surge absorber means is connected to the upper layer conductive member and the other end is grounded. 9 [Operation] The operation of the means of this invention is as follows.

The paper guide is placed on the conductive member in the upper layer of the printer mounting section, and the paper guide and the conductive member are electrically connected.

In addition, the surge absorber means, which is connected to the upper conductive member and whose other end is grounded, exhibits a low resistance value to high-voltage electricity and a high resistance value to low-voltage electricity. have.

Therefore, when setting printing paper, high-voltage static electricity noise discharged from the human body to the conductive member on the upper layer of the printer mounting part and the paper guide flows to the land via the surge absorber means, so that thermal noise is generated from the paper guide. There is no secondary discharge to the head.

In addition, during normal use without the risk of high-voltage electrostatic noise discharge, the surge absorber means exhibits a high resistance value, and the thermal head and thermal paper , the paper guide, etc. are in an electrically floating state, and leakage current due to the movement of ions contained in the thermal paper inevitably flows to the thermal head.

With b'C, we devised the configuration of the printer fixing plate to prevent electrolytic corrosion.
Damage to the thermal head due to static electricity noise can be prevented at the same time.

[Example] Hereinafter, one embodiment will be described with reference to FIG.

FIG. 1 is a diagram showing the configuration near the print head of a thermal printer, which includes a thermal head 1, a paper guide 3, a printer fixing plate 6, a paper feed roller 7, a platen 8, and a surge absorber 9. .

The thermal paper 2 is guided by a paper guide 3 and fed between the thermal head 1 and a platen 8 by a paper feed roller 7. Then, a plurality of heating elements (
(not shown) electrically controls the heat generation of the thermal head 1.
By pressing the thermal paper 2 against the platen 8, the leuco dye, phenol dye, etc. contained in the thermal paper 2 are partially colored to perform printing. Note that this thermal printer can also print on ordinary printing paper other than the thermal paper 2 by using an ink ribbon.

The paper guide 3 has an "F" shape in relation to the constituent elements of the pond, and due to the requirements for workability, adhesion, etc. based on its shape, the material is metal, and it has good conductivity. have.

The printer fixing plate 6 has a three-layer structure, with the upper layer being a conductive earth pan 6a and the intermediate layer below it being an insulating sheet 6.
b. The lower layer is a metallic substrate 6C. The paper guide 3 is fixed onto the upper earth pan 6a with screws (not shown), and the earth pan 6a and the paper guide 3 are electrically connected. Further, this earth pan 6a is grounded via a surge absorber 9.

This surge absorber 9 has a characteristic of exhibiting a low resistance value for high voltages and a high resistance value for low voltages.

Note that the upper layer of the printer fixing plate 6 is an earth pan 6a.
It is also possible to have a two-layer structure in which the lower layer is a substrate made of an insulating material, but in this embodiment, as described above, by using a three-layer structure and making the lowest layer substrate 6c metallic, In addition to increasing its strength, it also absorbs miscellaneous noise from all directions.

Next, the effect of preventing damage to the thermal head due to electrolytic corrosion, electrostatic noise, etc. will be explained.

First, the galvanic corrosion prevention effect will be explained.

During normal use, when there is no influence from high-voltage static electricity noise, etc., the surge absorber 9 exhibits a high resistance value, and when looking at the thermal head 1, thermal paper 2, paper guide 3, etc. from an electrical circuit perspective, The current path in the direction of the surge absorber 9 is closed. Furthermore, since the insulating sheet 6b exists below the printer fixing plate 6, the current path in that direction is also closed.

Therefore, an electric circuit including the thermal head 1, the thermal paper 2, and the paper guide 3 is not formed;
, the paper guide 3, etc. are in an electrically floating state.

Therefore, even if the protective film layer 1a (second layer) of the thermal head 1
Even if there is a pin pole in the paper (see figure), the leakage current accompanying the movement of ions contained in the thermal paper 2 will not flow to the thermal head 1, and due to the electrochemical reaction in the process of this leakage current flowing, the second The electrode layer 1b of the thermal head 1 shown in the figure is not electrolytically eroded.9 Next, the effect of preventing damage to the thermal head due to static electricity noise will be explained.

When setting the thermal paper 2 in the device, high-voltage static electricity accumulated on the human body may be discharged to the paper guide 3 and the earth pan 6a.The surge absorber 9 has a low The resistance value increases, and a current path toward the surge absorber 9 is opened.

Therefore, the high voltage static electricity discharged to the paper guide 3 and the earth pan 6a flows to the ground through the surge absorber 9.

Therefore, the high-voltage static electricity discharged to the paper guide 3 and the ground pan 6a is no longer secondary discharged to the thermal head 1, and the thermal head 1 due to static electricity
9 [Effects of the Invention] According to the present invention, damage to the thermal head due to electrolytic corrosion and electrostatic noise can be prevented, and the life of the thermal head can be extended.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of an embodiment, Figure 2 is a sectional view showing the configuration of a thermal head, Figure 3 is a diagram for explaining the principle of electrolytic corrosion in a conventional thermal head, and Figure 4 is a diagram of a conventional thermal head. FIG. 9 is a diagram showing an improved invention that prevents electrolytic corrosion of the head. 9 ■... Thermal head, 3... Paper guide, 6...
Printer fixing plate, 6a... Earth pan, 6b... Insulating sheet, 9... Surge amplifier. 1. Applicant Casio'! :Lki Co., Ltd.

Claims (1)

[Scope of Claims] A thermal printer that prints using a thermal head includes: a printer mounting portion in which a conductive member is laminated as an upper layer and an insulating member is laminated as a lower layer; What is claimed is: 1. A thermal printer comprising: a paper guide having a conductive structure; and surge absorber means connected to the upper conductive member and having the other end grounded.