JPH0424231B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thick film type thermal recording head used in thermal recording devices such as printers and facsimiles, and a method for adjusting its resistance value.

[Prior art]

2. Description of the Related Art A thermal recording device such as a printer or a facsimile machine uses a thermal recording head to perform thermal recording on thermal paper or plain paper overlaid with an ink donor sheet. There are two types of thermal recording heads: thick film type and thin film type.

FIG. 1 shows an example of a thick-film type heat-sensitive recording head. In this thick film type thermal recording head, a heating resistor 2 is linearly provided on the upper surface of a substrate 1. A plurality of electrodes 3 are provided at intervals on one side of the heating resistor 2 in the width direction.
Further, on the other side of the heating resistor 2 in the width direction, a plurality of other electrodes 4 are provided at intervals. These electrodes 3 and 4 are arranged alternately, and one end of each is embedded in the heating resistor 2. One end of each of the heating resistor 2 and both electrodes 3, 4 is covered with a wear-resistant layer (not shown).

In this thick film type thermal recording head, one electrode 3
When a voltage is applied to the other electrode 4 adjacent thereto, the heating resistor 2 generates heat during this time. Therefore, thermal paper or an ink donor sheet and plain paper overlaid thereon are brought into pressure contact with the heating resistor 2, and both electrodes 3 and 4 are pressed according to the image information.
When the heating resistor 2 between the two is selectively heated, image information is recorded.

By the way, this thick-film type thermal recording head has the advantage that the heating resistor 2 has strong mechanical strength and can withstand overload compared to the thin-film type, but it has the problem that its resistance value varies considerably. It was hot. For this reason, this thick film type thermosensitive recording head has the disadvantage that power consumption is large in the portions with low resistance values, and as a result, the overall power consumption is large. Further, although this thick film type thermosensitive recording head can perform halftone recording by controlling the applied voltage, it has a drawback in that good halftone recording cannot be performed due to variations in resistance value.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and provides a thick film type thermal recording head that can make the resistance value of a heating resistor even more uniform, and the creation of such a thick film type thermal recording head. The purpose of the present invention is to provide a resistance value adjustment method.

[Structure of the invention]

In the first invention, a plurality of first electrodes are arranged parallel to each other at specific intervals and aligned such that one end thereof is located on the same straight line, and the first electrodes are arranged at specific intervals. A plurality of second electrodes are arranged parallel to the first electrodes with the same width between the electrodes, and a plurality of second electrodes are formed in a straight line along the portions of the first and second electrodes that are inserted into each other. A heating resistor made of a uniform resistance material is attached to a first or second electrode corresponding to a position separated by a predetermined distance from the heating resistor, and electric power is applied to the heating resistor by selecting one of them. Accordingly, the thick film type thermosensitive recording head is provided with a plurality of resistance value correction electrodes for increasing the resistance value of the power application portion of the heating resistor compared to other portions.

In other words, since a plurality of resistance value correction electrodes are arranged in this thick film type thermal recording head, if the resistance value of a part of the heating resistor is lower than the target value, that part can be adjusted. The resistance value can be increased by selecting a pair of resistance value correction electrodes in such a way that they are sandwiched between them and applying electric power between them in advance. This makes it possible to realize a thick film type thermal recording head with uniform resistance values.

Further, in the second invention, a plurality of first electrodes are arranged parallel to each other at specific intervals and aligned such that one end thereof is located on the same straight line;
A plurality of second electrodes are arranged in parallel with the first electrodes so as to fit between the first electrodes with the same width at the above-mentioned specific intervals, and the first and second
The first and second heating resistors of a thick film type thermosensitive recording head have heating resistors made of a uniform resistance material formed in a straight line along the mutually inserted portions of the electrodes.
In a resistance value adjustment method of adjusting the resistance value of each heating element of a heating resistor separated by electrodes, the resistance value of each heating element of the heating resistor is measured, and the resistance value is lower than the target resistance value. Identify areas where multiple heating elements with different resistance values exist locally,
A predetermined voltage is applied across this region of the heating resistor to change the resistance value of the plurality of heating elements to sometimes exceed the target resistance value described above.

That is, according to this resistance value adjustment method, the resistance value of each heating element of a thick film type thermal recording head is measured, and an area where a plurality of heating elements having a resistance value lower than a target resistance value locally exists is detected. Identify. Since a thick-film type thermosensitive recording head generates heat by dividing a single heat-generating resistor by electrodes, the heat-generating elements with low resistance tend to be concentrated in a certain location. Therefore, once such a region is identified, a predetermined voltage is applied across it, and the resistance values of these multiple heating elements are simultaneously changed to a target resistance value or higher, thereby making the resistance values uniform. I have to.

〔Example〕

The present invention will be explained in detail with reference to Examples below.

The same parts as in Fig. 1 are given the same reference numerals as in Fig. 2.
The figure shows the main parts of a thick film type thermosensitive recording head in one embodiment of the present invention.

This thick film type thermal recording head is for A4 size, for example, and has a resolution of 8 dots/mm and 1728 dots/line. In this thick film type thermal recording head, the heating resistor 2 is divided into 54 groups of 32 dots each, and the other 55 electrodes located at the boundaries of each group and at both ends of the heating resistor 2 are connected to 4 groups. An electrode 11 for resistance value correction is provided.

By the way, the heating resistor 2 of the thick film type thermal recording head
When the resistance values of each heating element are investigated, for example, the resistance values are scattered in the shaded ranges in FIGS. 3 and 4, and there is considerable variation. However, in the example shown in FIG. 3, especially one end 1 of the heating resistor 2
The resistance value of part 2 is much lower than other parts. In the example shown in FIG. 4, the resistance value of a portion 13 appropriately distant from one end of the heating resistor 2 is considerably lower than that of other portions.

Therefore, the resistance value correction electrodes 11 at both ends of the group corresponding to the portion (12 or 13) where the resistance value of the heating resistor 2 is considerably lower than the other portions are connected to the electrodes 11 for adjusting the resistance value via probe pins, for example, with a normal printing power (0.6W). degree)
Apply a certain amount of higher power than the Then, as is clear from the results of the well-known step stress test, the resistance value of the group of heat generating resistors 2 increases to some extent and is maintained in that state. for example
When a power of 1.1W was applied for about 3 minutes, the resistance value increased by about 20% and was maintained at that state. At this time, the mechanical and electrical strength of the heating resistor 2 did not change at all. If the result of measuring the resistance value of the relevant group of heating resistor 2 is that it is still lower than other parts, then re-evaluate the resistance value at that point.
Applying a power of 1.1 W further increases the resistance value of the group. In this way, the resistance value of the heating resistor 2 can be made substantially uniform throughout.

Here, the step stress test will be briefly explained. A step stress test is a test that is widely used to estimate the life characteristics of a heating resistor with respect to applied power. FIG. 5 shows the results of a step stress test on a 32-dot heating resistor with a resolution of 8 dots/mm. As is clear from this figure, when the applied power is about 1.1 W, the resistance value increases by about 20% and is maintained in this state.

In addition, the resistance value of each 32 dots, that is, each group, was checked through the electrode 11 for resistance value correction.
The resistance value may be corrected based on the result. In this way, it is not necessary to check the resistance value of each heating element of the heating resistor 2, making it easy to measure the resistance value, and also significantly shortening the measurement time.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to make the resistance value of the heat generating resistor more uniform over the entire area, so there is no part where the resistance value is extremely low, thereby reducing power consumption. It is also possible to perform good halftone recording. Furthermore, according to the present invention, parts of the heating resistor corresponding to a plurality of heating elements are energized at the same time, so the resistance value can be adjusted more easily than in the case where the resistance value of each heating element is adjusted individually. Another effect is that the time required for the process can be shortened.

[Brief explanation of drawings]

FIG. 1 is a partial plan view showing an example of a conventional thick film type thermal recording head, FIG. 2 is a plan view showing essential parts of a thick film type thermal recording head according to an embodiment of the present invention, and FIG. FIG. 4 is a diagram showing examples of variations in resistance values of heating resistors, and FIG. 5 is a diagram showing the results of a step stress test. 2... Heat generating resistor, 3, 4... Electrode, 11...
Electrode for resistance correction.

Claims (1)

[Scope of Claims] 1. A plurality of first electrodes arranged parallel to each other at specific intervals, and aligned such that one end thereof is located on the same straight line; A plurality of second electrodes are arranged parallel to the first electrodes with the same width between the electrodes, and a plurality of second electrodes are formed in a straight line along the mutually intruded portions of the first and second electrodes. A heating resistor made of a uniform resistance material, and one each attached to the first or second electrode corresponding to a position separated by a predetermined distance from the heating resistor, and applying electric power to one of them. What is claimed is: 1. A thick-film thermosensitive recording head comprising a plurality of resistance value correction electrodes for increasing the resistance value of the power application portion of the heating resistor relative to other portions. 2. A plurality of first electrodes arranged parallel to each other at specific intervals and aligned so that one end thereof is located on the same straight line, and an equal width between the first electrodes at the specific intervals. A plurality of second electrodes are disposed parallel to the first electrodes in a manner that they are interdigitated with each other, and a uniform resistance material is formed in a straight line along the mutually interdigitated portions of the first and second electrodes. In the resistance value adjustment method of adjusting the resistance value of each heating element of a heating resistor separated by a first and second electrode of a thick film type thermal recording head having a heating resistor, the heating resistor comprises: The resistance value of each heating element of the resistor is measured, a region where multiple heating elements with a resistance value lower than the target resistance value are locally present is identified, and a predetermined voltage is applied across this region of the heating resistor. 1. A method for adjusting a resistance value of a thick-film type thermal recording head, characterized in that the resistance values of the plurality of heating elements are simultaneously changed to a value equal to or higher than the target resistance value by applying .