JPS63185647A - Thermal head - Google Patents

Abstract

PURPOSE:To detect using up of ribbon stably with high accuracy, by integrally forming a pair of electrodes for detecting using up of ribbon in parallel with heating elements arranged in row on the substrate of a thermal head. CONSTITUTION:When printing is carried out, an ink ribbon slides against an anti-abrasion layer 5 and a pair of electrodes 4a, 4b arranged on one face of a substrate 1 so as to drive heating elements 2, 2,... selectively thus carrying out dot printing onto a print sheet through the ink ribbon. If predetermined amount of ink ribbon has been wound up and there is no residual ink ribbon, a conductive portion arranged at the end portion is fed to a thermal head and slided against a pair of electrodes 4a, 4b, and a ribbon used-up detection signal is produced when conduction between said electrodes 4a, 4b is detected. Here, said conductive portion slides while contacting tightly with head face due to the pressure contact force of head against a platen, and also contacts tightly with a pair of electrodes 4a, 4b, thereby using up of ribbon can be detected stably with a high reliability.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention is used in a thermal transfer printer, in which any heating element is selected from a plurality of heating elements arranged in a row. The present invention relates to a thermal head that prints character patterns on thermal paper or plain paper via a thermal transfer ink ribbon by controlling power supply.

(Prior Art) Conventionally, in a thermal transfer type printer, as a means of detecting so-called "ribbon breakage" when the remaining amount of thermal transfer ink ribbon runs out, a transparent part is formed at the end of the ink ribbon and the transparent part is removed. There are means for detecting ribbon breakage by optical detection, or means for detecting ribbon breakage by forming a conductive part at the end of the ink ribbon and electrically detecting the conductive part. In either case, a sensor must be installed at a predetermined position on the tape running path in front of the thermal head, which complicates the structure of both the tape cassette and the cassette support, and tends to cause problems in terms of accuracy. there were.

(Problems to be Solved by the Invention) As described above, in conventional thermal transfer printers, the ribbon breakage detection means is either optical detection means or electrical detection means, and the tape path in front of the thermal head is A sensor must be provided at a predetermined position on the top, which makes the structure of both the tape cassette and the cassette support complicated.
There were also problems with accuracy.

In a thermal transfer printer, the present invention has a structure in which ribbon breakage detection electrodes are integrally formed on the substrate of the thermal head, thereby eliminating the need for a separate ribbon breakage detection mechanism on the tape running path. It is an object of the present invention to provide a thermal head configured to be able to detect ribbon breakage of a thermal transfer ink ribbon with high accuracy.

[Structure of the Invention] (Means for Solving the Problems) The present invention has a structure in which ribbon breakage detection electrodes are integrally formed on the substrate of the thermal head, and the heating elements of the thermal head are arranged in a row. A pair of electrodes are provided on the surface of the substrate in parallel with the heating element.

(Function) Since the electrode for detecting ribbon breakage is integrally formed on the substrate of the thermal head, there is no need to secure installation space for the ribbon breakage detection mechanism on the tape running path from the viewpoint of the device configuration. Since the number of parts can be reduced, the overall configuration of the device can be simplified, and in terms of functionality, the ribbon surface can be brought into close contact with the detection electrode by using the pressure force of the head against the platen, allowing for stable and highly accurate ribbon cutting. Can be detected.

(Example) The present invention will be described in detail below with reference to FIGS. 1 to 3.

First, one embodiment of the present invention will be described with reference to FIGS. 1 and 2. Here, a conductive part made of conductive foil, for example, is formed at the end of the ink ribbon, and ribbon breakage is detected by detecting conductivity by the conductive part.

FIG. 1 is a plan view showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the same.

In the figure, reference numeral 1 denotes a substrate of a thermal head made of an electrically insulating material such as an alumina magnetic member. 2゜2, . . . are a plurality of heating elements arranged in a column on one side of the substrate 1 in a number corresponding to the number of high dots of printed characters;
They are arranged at regular intervals on a band-shaped glaze 7 made of, for example, a glass layer, which has been previously formed on one side of the substrate 1. 3,3°... is the heating element 2.2. It is a unit signal path (conductive pattern) for supplying drive current to... 4a.

4b is the heating element 2, 2. A pair of electrodes for detecting ribbon breakage are provided on one side of the substrate 1 in parallel with . For example, the dummy glaze 6 is juxtaposed on a band-shaped dummy glaze 6 made of a glass layer. 5 is the heating element 2, 2.5 except for the pair of electrodes 4a, 4b. ...
This is a wear-resistant layer formed by, for example, glass coating, and is provided so as to cover one side of the substrate 1 including the substrate.

In the configuration shown in FIGS. 1 and 2 above, during the printing process, the ink ribbon comes into sliding contact with the wear-resistant layer 5 provided on one side of the substrate 1 and the pair of electrodes 4a and 4b, generating heat. Body 2, 2. Dot printing is performed on the printing paper via the ink ribbon by the selective heat generation drive of...

Here, a predetermined amount of the ink ribbon is wound up so that there is no remaining amount, and the conductive part provided at the end of the ribbon is supplied to the thermal head to form a pair of electrodes 4a.

When it comes into sliding contact with electrode 4b, a ribbon breakage detection signal is generated by detecting continuity between the electrodes 4a and 4b. At this time, the conductive portion slides in close contact with the head surface due to the pressure of the head against the platen, and forms a pair of electrodes 4a.

4b as well, so that stable and reliable ribbon breakage detection can be performed. Further, on the substrate 1 of the thermal head, a pair of electrodes 4a for detecting ribbon breakage,
4b is integrally formed, there is no need to secure installation space for the ribbon breakage detection mechanism on the tape running path, the number of parts can be reduced, and the overall configuration of the apparatus can be simplified.

FIG. 3 shows another example of the present invention, in which the head surface including a pair of electrodes 4a and 4b is covered with a wear-resistant material 5, and the electrode 4a is covered with a wear-resistant layer 5.

This makes it possible to realize a non-conducting capacitance sensing type ribbon breakage detection mechanism that detects ribbon breakage by variation in oscillation frequency due to change in capacitance between the capacitances 4b and 4b. That is, the ink ribbon is wound up for a predetermined number of meters until there is no remaining amount, and the conductive part provided at the end of the ribbon is supplied to the thermal head, and the conductive part is applied to the pair of electrodes 4a and 4b via the abrasion resistant part 15. When located at , the same electrode 4a.

The capacitance between 4b changes. By converting the variation in the firing frequency due to this capacitance change into a voltage change using an S-shaped detection method similar to FM modulation, it is possible to obtain a ribbon breakage detection signal similar to that of the above embodiment.

With this structure, the head surface including the pair of electrodes 4a and 4b has a resistance of 1! Since the electrodes 4a and 4b are coated with the JK layer 5, abrasion of the electrodes 4a and 4b is also avoided, thereby ensuring stable ribbon breakage detection operation over a long period of time. In this embodiment, as in the above-mentioned embodiment, the conductive portion slides in close contact with the head surface due to the pressure of the head against the platen, so that stable and reliable ribbon breakage detection can be performed. , a pair of electrodes 4a for detecting ribbon breakage on the substrate 1 of the thermal head;
4b is integrally formed, there is no need to secure installation space for the ribbon breakage detection mechanism on the tape running path, the number of parts can be reduced, and the overall configuration of the apparatus can be simplified.

[Effects of the Invention] As detailed above, according to the present invention, the ribbon breakage detection electrode is integrally formed on the substrate of the thermal head, and the heating elements of the thermal head are arranged in a row. By adopting a configuration in which a pair of electrodes are provided on the surface of the substrate in parallel with the heating element, there is no need to secure installation space for the ribbon breakage detection mechanism on the tape running path, and the number of parts can be reduced. Therefore, the configuration of the entire apparatus can be simplified, and since the ribbon surface portion can be brought into close contact with the detection Im by using the pressure of the head against the platen, ribbon breakage can be detected stably and with high precision.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing one embodiment of the present invention, FIG. 2 is a cross-sectional view of the same embodiment, and FIG. 3 is a cross-sectional view showing another embodiment of the present invention. 1... Substrate, 2,2. ...Heating element, 3,3.
... Unit signal path, 4a, 4b... Pair of electrodes, 5... Wear-resistant layer, 6... Dummy glaze, 7...
...Glaze. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 3

Claims (4)

[Claims] (1) In a thermal head in which a plurality of heating elements are arranged in a row on one side of a substrate made of an electrically insulating material,
A thermal head characterized in that a pair of electrodes are provided on one side of the substrate in parallel with the heating elements arranged in a row. (2) The thermal head according to claim 1, wherein the pair of electrodes has a conductive surface. (3) The thermal head according to claim 1, wherein the surfaces of the pair of electrodes are coated with an abrasion-resistant layer along with the heating element. (4) The thermal head according to claim 1, wherein the pair of electrodes is provided on a dummy glaze provided on one side of the substrate corresponding to the heating element.