JPH0513754U - Thermal print head - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent the occurrence of open defects due to thermal paper ions of the electrodes formed on the insulating substrate that compose the thermal print head. [Structure] An individual electrode 2, a common electrode 3, a heating resistor 4, and an electrically insulating protective film 5 are formed on a glaze substrate 1.
Since the protective film 5 has fine pinholes, the ions of the thermal paper corrode the electrodes through the pinholes. In order to prevent this, a conductive film 6 is formed on the protective film 5, and a part of the conductive film is connected to the ground electrode 7. [Effect] It is possible to prevent the electrode from corroding and to release the static electricity generated in the vicinity of the heating resistor to the ground electrode to prevent the generation of the spark.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a thermal print head.

[0002]

[Prior Art]

 FIG. 2 shows a partial vertical sectional view of a conventional thermal printhead. The heating resistor 4, the individual electrode 2 and the common electrode 3 for energizing the heating resistor 4 are formed on the glaze substrate 1, and covered with a protective film 5 made of electrically insulating glass to protect them. There is. This protective film 5 is extremely thin and has fine pinholes. For this reason, the individual electrode 2 and the common electrode 3 made of gold, which are connected to the heating resistor 4 through the fine pinholes of the protective film 5 in which the ionic components are from the thermal paper (hereinafter, the two electrodes will be collectively referred to as “electrodes”). This causes corrosion of the gold electrode) and causes the open failure of the gold electrode. Further, if electrostatic sparks are generated in the vicinity of the heat-generating resistor, the resistance value will be significantly reduced and printing defects will occur.

[0003]

[Problems to be solved by the device]

 The present invention provides a thermal print head that prevents the occurrence of open defects of the gold electrode and the electrostatic spark due to the ions of the thermal paper.

[0004]

[Means for Solving the Problems]

 The present invention is characterized in that a conductive film is formed on the protective film made of the electrically insulating glass.

[0005]

【Example】

 FIG. 1 is an embodiment of the device of the present invention. FIG. 1A is a longitudinal sectional view of a main part of a thermal print head of the present invention, and FIG. 1B is an enlarged plan view of the main part. An individual electrode 2, a common electrode 3, and a heating resistor 4 are formed on the glaze substrate 1, and the surface of the head substrate including these is protected by an electrically insulating glass film 5. Further, a conductive film 6 is formed on the glass film 5 over the entire length of the heating resistor on the surface of the head substrate including the heating resistor 4, on the glass film 5. Then, a part of the conductive film 6 is connected to the pad 8 of the ground electrode 7 formed on the glazed substrate 1.

The conductive film 6 has a film thickness of 1 μm or less so as not to drop the heat generation temperature on the surface of the heat generating resistor. Further, the sheet resistance value of the conductive film is 10 ³ Ω or more. Instead of connecting the conductive film to the ground electrode 7, it is possible to connect a conductive film to the common electrode. In this case, the heat sink and the cover (not shown) are the ground potential and the conductive film is It is necessary to raise the sheet resistance value to about 10 ⁶ Ω, which reduces the effect by half.

[0007]

[Effect of the device]

 The movement of the ions that cause the open defect of the gold electrode does not affect the gold electrode under the protective film because the migration of the ions flows to the ground electrode through the conductive film. Sparks do not occur because they escape to the ground electrode, and the resistance change of the heat-generating antibody can be prevented. Further, even if there are small pinholes in the protective film, the conductive film covers the thin film, so that the film thickness of the protective film itself can be reduced to 5 μm or less, so that the heat generation efficiency can be improved.

[Brief description of drawings]

FIG. 1A is a longitudinal sectional view of an essential part of the present invention, FIG.
3B is an enlarged plan view of a main part.

FIG. 2 is a longitudinal sectional view of a main part of a conventional example.

[Explanation of symbols]

1 ... Glazed substrate 2 ... Individual electrode 3 ... Common electrode 4 ... Heating resistor 5 ... Protective film 6 ... Conductive film 7 ... Ground electrode

Claims (2)

[Scope of utility model registration request] 1. A heating resistor formed on an insulating substrate, an individual electrode and a common electrode for energizing the heating resistor, and an electrical element for protecting the heating resistor, the individual electrode, and the common electrode. A thermal print head comprising: an insulating protective film; and a conductive film formed on the electrical insulating protective film over the entire length of the heating resistor on the surface of the insulating substrate including the heating resistor. 2. The thermal printhead according to claim 1, wherein a part of the conductive film is connected to a ground electrode formed on an insulating substrate.