JPS6129554A - Thermal printing head - Google Patents

Abstract

PURPOSE:To prevent the breakdown of heating elements and a protective layer due to high-tension discharge by exposing and arranging a grounding electrode near a large number of the heating elements disposed to a row shape and grounding the electrode to a ground electrically connected in common with the heating elements. CONSTITUTION:A thermal head 5' is manufactured in such a manner that a radiator plate 10 in Al, etc. is affixed onto the back of a ceramic substrate 1 and a glazed layer 11, a heating element 2 consisting of Ta2N, etc., lead wires 3 in Al, etc. supplying the heating element 2 with power, and a protective layer 4 composed of SiO2, etc. are laminated onto the surface of the substrate 1 in succession. A grounding electrode 12 in Al, etc. is laid while being approached to the heating element 2 and exposed onto the protective layer 4. A section between the radiator plate 10 and the ceramic substrate 1 is filled with silicone grease 13 in order to improve thermal conductivity. The grounding electrode 12 is constituted so as to be connected to a frame ground for a device through a GND wire 14 of thermal head itself.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a thermal print head used in a heat-sensitive coloring type or heat-sensitive transfer type thermal recording device.

[Prior art]

Conventionally, this type of thermal print head 5 has a heating element 2 on a ceramic substrate 1, a lead wire 3 for supplying power to the heating element 2, and a protective layer 4, as shown in FIG.
It is constructed by laminating layers. The basic structure of a transfer type thermal recording device, which is an example of a thermal recording device using the thermal print head 5, is to apply heat-melting ink on one side between the thermal print head 5 and a platen roller 6 disposed opposite to it. The coated ink film 7 and the recording paper 8 to be transferred are brought into close contact and pressurized, and the heating element 2 is energized to generate heat in response to a print signal, melting the heat-melting ink on the ink film 7 and transferring it to the recording paper 8 to be transferred. This is for printing.

[Problem that the invention seeks to solve]

Since the base material of the ink film 7 is an insulator such as a polyester film, it is easily charged to a high potential when traveling inside the device, and the protective layer 4 is an electrical insulator and has a thickness of about 7 μm. Therefore, discharge occurs between the ink film 7 charged to a high potential and the heating element 2 or the lead wire 3, causing cracks in the protective layer 4,
The heat generating element 2 may be burnt out, resulting in a serious drawback in which printing becomes impossible in that area.

' The present invention provides a thermal print head that solves the above-mentioned drawbacks and achieves good print quality by eliminating static electricity immediately before a highly charged ink film or colored thermal recording paper approaches a heating element and causes discharge. This is what we provide.

[Failure to solve the problem]

In the present invention, a ground electrode 12 is exposed and arranged near the heat generating element 2, and the electrode 12 is grounded to a common ground electrically with the heat generating element 2.

[Effect]

Immediately before approaching the heat generating element 2, the ink film 7 or the transfer recording paper 8 is brought into contact with the ground electrode 12 to eliminate the electric charge on the ink film or the like.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, a thermal print head 5' which is a first embodiment of the present invention has a heat dissipation plate 10 made of M or the like attached to the back surface of a ceramic substrate 1, and a glaze layer 11 on the surface of the substrate 1. A heating element 2 made of TazN or the like, and a lead wire 3.5i made of M or the like that supplies power to the heating element 2.
A protective layer 4 made of Oz, Ta5ks, or the like is laminated in order, and a ground electrode 12 made of M or the like is placed close to the heating element 2 and exposed on the protective layer 4 . Silicone grease 13 is filled between the heat sink 10 and the ceramic substrate 10 to improve thermal conductivity. The ground electrode 12 is configured to be connected to the frame ground of the apparatus via the GND line 14 of the thermal print head itself.

FIG. 2 shows the basic configuration of a transfer type thermal recording apparatus using a real-size print head.

Reference numeral 5' denotes a thermal print head having the structure shown in FIG. 1, and a platen roller 6 made of silicone rubber or the like is disposed at a position opposite to the thermal print head. 7 is an ink film made of a base material such as a polyester film coated with heat-melting ink on at least one side; a recording paper 8 to be transferred; and the thermal print head 5.
' and the platen roller 6, and the thermal head is energized and heated in accordance with a print signal to perform printing.

In FIG. 2, the ink film 7 or the transfer recording paper 8 is easily rubbed and charged to a high potential while traveling within the apparatus.

The highly charged ink film 7 or transfer recording paper 8 is conveyed between the thermal head and the platen roller 6, and just before it approaches the heating element 2, it is brought into contact with the exposed ground electrode 12 by the platen roller 6. It will be done. Therefore, before the protective layer 4 or heating element 2 is fatally damaged by discharge from the highly charged ink film 7 or transfer recording paper 8, the exposed ground electrode 12 causes the ink film 7 or transfer recording paper 8 to be damaged. Static electricity is removed.

〔Effect of the invention〕

As explained above, the present invention has a structure in which the ground electrode is exposed in the vicinity of the heating element, thereby having the effect of preventing destruction of the heating element and the protective layer due to high-pressure discharge.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional perspective view of a thermal print head showing an embodiment of the present invention, FIG. 2 is a diagram showing the basic configuration of a transfer type thermal recording device using the thermal print head of the present invention, and FIG. The figure shows the structure of a conventional thermal head and the basic configuration of a transfer type thermal recording device. 1... Ceramic substrate, 2... Heat generating element, 3...
Lead wire, 4... Protective layer, 5, 5'... Thermal print head, 6... Platen roller, 7... Ink film, 8... Recording paper to be transferred, 10... Heat sink, 11... Glaze layer, 12... Ground electrode, 13;
・Silicone grease.

Claims (1)

[Claims] (1) In a thermal print head in which a large number of heating elements are arranged in a row, a ground electrode is placed exposed near the heating elements, and the electrode is electrically grounded to a common ground with the heating elements. Features a thermal print head.