JPS6183054A - Preparation of thermal head - Google Patents

Abstract

PURPOSE:To reduce the irregularity in the resistance value of the heat generating resistor a thick film type thermal head, by reducing the resistance value by applying voltage pulse to the heat generating resistor. CONSTITUTION:The initial setting of a pulse condition such as the peak value Vs of apply voltage or the number (n) of pulses is performed by a calculation part 12. Next, probing is applied to a thermal head 7 of which the resistance value is equal to or more than a predetermined value R0 and, after the above mentioned set pulse is applied from the pulse generation circuit 10, the resistance value of the above mentioned thermal head 7 is measured by a resistance meter 11. The preceding measured value is compared with the lately measured value by the calculation part 12 and, if the lately measured value is low, said value is compared with the adjusted objective value R0 and, if it reached R0 or less, the peak value Vs of an apply voltage pulse is increased by DELTAV to apply voltage. At the same time, the ratio DELTAt/T of a pulse width DELTAt and a pulse cycle T is made contact corresponding to the peak value so as not to destruct the heat generating resistor and the number (n) of pulses are changed. By this method, the peak value is successively increased to apply voltage and the resistance value is adjusted to R0 or less to reduce irregularity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates primarily to a method of manufacturing a thermal head used in facsimiles and printers.

[Conventional technology]

Thermal heads, which do not require development or fixing, are noiseless, maintenance-free, and highly reliable, are becoming popular as thermal recording paper improves. In thermal recording, a recording current is applied to a resistor provided on a substrate, and the Joule heat generated by the current flowing through the resistor is used to color the thermal paper that is in contact with the resistor, or to color the ink on thermal transfer paper. melt the layers,
This is a technology that prints and records recording signal information on transfer paper.

A general structural diagram of the thermal head is shown in FIG.

The thermal head is made of Al, Au, and Ou on an insulating substrate (1).
A heat generating element is constituted by a lead part (2) made of a good electrical conductor material using a special technique, and a film-like element resistor (3) connected to the lead part at both ends thereof.

For the material of the insulating substrate (1), an alumina ceramic substrate or an alumina ceramic substrate with a glaze layer is often used.In the case of a thin film method, the material for the element resistor (3) is I″t Ta2N, Ta-8in□, Ta. -8
Materials such as Ni-CuT1□03 and the like are used.

In addition, in the case of the thick method, oxides of noble metals such as Ru□O, PtO, etc. are mixed with a glass material, applied, and sintered.

Although not shown, after forming the element resistor (3),
A glass film is fired to protect this.

When a constant voltage is applied to both ends of the lead portion of this thermal head for a certain period of time, heat is generated in the resistor portion due to Joule heat. This heat is transferred to the thermal paper (5) by the heat of the recording apparatus constructed as shown in FIG. 10, and the thermal paper (5) develops color and is printed on its surface. In addition, in Fig. 10, the 9th
The same symbols as in the figure indicate corresponding parts. P indicates the suppression direction of roll (4).

Generally, for example, in a thermal head for a facsimile, each head has about 9 or 2000 resistors arranged independently in parallel as heating resistors.

These heating resistors are heated to a surface temperature of about 250°C to 600°C by Joule heat, and the applied energy equivalent to reaching this temperature varies depending on the decomposition of each thermal head. Approximately o, zm, T(
joule) ~2 mJ is required.

Conventionally, there have been three types of thermal heads: a thin film type, a thin film type, and a semiconductor type, depending on the manufacturing process and material of the resistor. In the thin film type, a desired pattern is formed in advance on a screen or photoresist using a base-like resistive material, and the resistive material is printed or embedded using screen printing technology, and then baked as a post-process. A heating resistor is formed. For the thin film type, a tantalum-based material is mainly vapor-deposited or sputtered to form a basic pattern that can become a resistor, and then photo-etched to create an independent resistor with a desired pattern. In the semiconductor type, for example, resistance is diffused in a part of a silicon base material to form a resistor, and heat generated at the P-N junction surface is utilized, and almost the same means as in the semiconductor manufacturing process are used.

Of the above three manufacturing methods, the ones that have been put into practical use are the thin film type and the thin film type. By the way, the thin film type has the great advantage that although the manufacturing process is extensive, there is little variation in the resistance value of the heating resistor and a fine pattern can be formed. On the other hand, the thin film type can be manufactured at low cost through a relatively short manufacturing process, but it has the serious drawback of large variations in the resistance value of the heating resistor. Thermal recording is determined by the resistance value of the resistor and uses the generated Joule heat, so variations in resistance value naturally occur.
This causes unevenness in the image quality printed on it.

Fig. 1 shows an example of the resistance value Ft+*R2H----*''s of each element resistor constituting the thermal head.

Normally, the resistance variation of thin film type is uniform within ±5 inches to ±15 inches, whereas the thin film type has a uniform resistance variation of ±15 inches to ±3 inches.
Although the coefficient of 0 varies and it is inferior to the thin film type, it is the mainstream type that has the major advantages of high reliability represented by overload power and wear resistance, and low cost. This is because they have it.

Recently, even with the thin film type, it has become possible to form fine patterns as well as with the thin film type. For example, in the formation of a conductor pattern, a printed thickness of 3 .mu.m or more is conventionally required, but a conductor thickness of 300 OA or less can also be used. This advantage is due to the fact that the etching factor during photoetching is about the same as that of the thin film type, that is, almost zero, compared to the conventional etching factor of 20tm. On the other hand, in order to improve the variation in resistance value of thin film types, in addition to improving conventional screen printing technology such as improving mesh screens and metal mask screens, for example, the four-layer resistor described in Japanese Patent Publication No. 59-22675 has been developed. photo-etching, a method of embedding a four-layer resistor into a photoresist pattern as described in Japanese Patent Publication No. 57-18506, and a surface polishing treatment of a thick resistor as described in Japanese Patent Publication No. 54-99443. Furthermore, there is a method in which a four-way resistor is printed on a thin film conductor, as described in Japanese Patent No. 55-47597. these are,
This is an attempt to make the shape of the heating resistor uniform and to improve the variation in resistance value caused by this effect.

In addition, progress has been made in improving 4-resistance materials. Suitable examples of the 4-common resistance material include ruthenium oxide, high-melting frit glass, and zirconium oxide described in JP-A-53-9544 and JP-A-53-95439. However, these were mainly improved to maintain reliability as a thin film thermal head.
This has not resulted in an improvement in the variation in thermal resistance. However, if the shape of the thick film resistor is geometrically arranged to be the same as that of the thick film resistor, there is a question as to whether the variation in resistance value will actually be the same as that of the thick film resistor. Theoretically, the resistance value of the resistor is expressed by the following equation.

R=p・□ (Ω) w, t Here, p: Specific resistance of resistor (Ω-am) I! : Length of the resistor (am) W: Width of the resistor (cm) t: Thickness of the resistor (Cω) Screen-printed heating resistors usually have the length of the resistor (l), the width of the resistor ( W) and the thickness of the resistor (1) both vary slightly, but ultimately the problem is 4.
This is the variation in the resistivity itself of the resistor, which is caused by the difference in the degree of bonding that occurs during firing of ruthenium oxide, glass frit, zirconium oxide, etc., in which the resistive material basically maintains a certain particle size. This is the variation in resistance value.

This problem cannot be solved even by improving the strict screen printing and firing conditions of the manufacturing process, or even by improving the pre-processing and post-processing steps for manufacturing these heating resistors.

This is because the particle size of ruthenium oxide, etc. is
As stated in No. 4, 5/Im is a non-negligible size, and the determination of the resistance value of a thick film resistor is mainly based on the Mo-process at the contact interface with the ruthenium oxide glass frit. This is because the cause is ultimately due to the heterogeneous bonding state of Me (metal-inulator metal). Basically, there are four resistance materials: firing temperature, atmosphere,
The reason why the resistance value changes significantly despite the firing speed and the same material is presumed to be due to the change in the bonding state of M, -1, and -M.

Therefore, recently, four-layer resistance materials such as ruthenium oxide and glass frit, which have finer particle sizes, have become commercially available. However, the desired effect was not achieved.

From the above, it can be seen that unless the variation in resistance due to non-uniformity of the contact interface is not improved, the variation in resistance value will not be improved. By the way, in order to improve variations in resistors, laser trimming methods and the like have been used to mainly adjust resistance values on thick film circuit boards, thin film circuit boards, and the like. Also, JP-A-58-73
In the liquid jet recording head described in No. 60 or JP-A-58-7360, the thin film resistive element is laser trimmed to adjust the resistance value to match the electro-thermal conversion characteristics.

[Problem that the invention seeks to solve]

All conventional methods for improving the variation in resistance values of thick film resistors have been insufficient. Chemical trimming methods, which are susceptible to impact, cannot be used because of the mechanical vibration caused by the movement of the rotating roller that is located above the heating resistor and presses against the thermal paper. In addition, since a uniform temperature distribution is required, the shape of the heating resistor is also an important factor. Mechanical trimming methods such as laser, diamond cutting, and sandblasting are not used because the change in shape deteriorates the performance of the thermal head. The object of the present invention is to provide a method for manufacturing a thick-film thermal head by changing the resistance value of the heating resistor without changing its shape.

[Means for solving intervening points]

The present invention reduces resistance by applying voltage pulses to the heating resistor of the thermal head, thereby reducing variations in resistance.

[Effect]

In this invention, by utilizing the fact that the resistance value of the heat generating resistor is reduced by the application of the il: voltage pulse, it is possible to significantly reduce the variation in the resistance value. As a result, manufacturing unevenness in the print quality of the thermal head can be significantly reduced.

[Embodiments of the invention]

In the method of manufacturing a thermal head according to the present invention, a process for reducing the resistance value of the heating resistor is performed after the main production process. That is, after forming the heating resistor, the lead wire, and the protective glass on the substrate, the process of reducing the resistance value according to the present invention is performed.

FIG. 1 is a diagram showing the principle of the method for producing a thermal head according to the present invention.

This invention utilizes the phenomenon that when a voltage is applied to a four-way resistor, the resistance value decreases. This phenomenon is caused by M Engineering S (
Metal-engineering-nsu1ator-semiconau
The insulator of the 4-layer resistor with the structure
It is also believed that this is due to the voltage-induced breakthrough of the In any case, it is certain that the physical properties of the resistor change with the application of voltage.

FIG. 1 shows a case where the resistance values of the heating resistors whose initial resistance values are R, , R2, and R3 are adjusted to R8.

First, measure the resistance value of each heating resistor and compare it with the target resistance value R6.Do not apply voltage pulses to heating resistors with a resistance value lower than Ro, such as 5R4. A voltage pulse is applied to the heating resistor having resistance values R, , R2°R3.

First, the initial setting of the wave height value is V. A voltage pulse is applied to reduce the resistance value. Measure the resistance value after the decrease, and if the value is R6 or more, it is V. A voltage pulse of +ΔVtDea value is applied. After that, measure the resistance value, and the value is R8
If it is above, V. A voltage pulse having a peak value of +2ΔV is applied. In this way, the resistance value is gradually decreased while gradually increasing the peak value of the applied voltage pulse until the resistance value becomes R8 or less. When the resistance value becomes R8 or less, the adjustment ends there. In this way, the resistance value of the heating element is made to be within a certain range of R8 or less. Since the purpose of the present invention is to reduce the variation in resistance value, it is not enough that the resistance value is R6 or less, but it is required that it be within a certain range of R0 or less. Therefore, the resistance value is gradually decreased and stopped when it becomes less than Ro.

FIGS. 2 and 3 are diagrams showing the distribution of resistance values of the heating resistor when the manufacturing method of the present invention is not implemented and when it is implemented. A number of heat generating resistors are grouped into one group, and the maximum value is indicated by a white circle, the average value is indicated by a black circle, and the minimum value is indicated by an x.

If it is not carried out, the variation in resistance value will be very large, but
It can be seen that when implemented, the variation is almost eliminated.

FIG. 1 is a block diagram showing an example of an apparatus used in the production method of the present invention.5 FIG. 5 is a waveform diagram of the main signals shown in FIG.

(6) is a probing device that presses a probe against the thermal head (7) to be adjusted; (8) is a relay network that guides the applied voltage pulse to the desired heating resistor; (9) is a voltage application and αO is the pulse generation circuit that generates the adjustment voltage pulse, αη is the resistance meter, (2) is the calculation unit, α is the input/output part, and α is the central processing unit (hereinafter referred to as cpσ), αQ is memory, α0
is the keyboard, and αη is the printer.

The procedure for reducing the resistance value according to the present invention will be explained.

A setting signal for the peak value Vθ of the applied voltage from the calculation unit (2), 1
A setting signal for the number n of pulses included in one voltage application is given. Voltage application start signal 13T from calculation unit (2)
Upon receiving ART, the pulse generating circuit αO sends the ENABIJ signal back to the calculation section. Further, the switch (9) is switched to the pulse generating circuit αO side. During the period after the FiNABLK signal is output, changes in the peak value Va and generation of the 5TART signal are prohibited. This is because the peak value Vs should not be changed while the voltage pulse is being applied, and the start signal 13TART for applying the next voltage pulse should not be issued until the application of the current voltage pulse is finished. It is. When a certain period of time T has elapsed after the application of the 8TART signal, the pulse generation circuit αO sends n pulses with a peak value of v8 to the switch (9), through the IJ relay network (8), and to the heating resistor of the thermal head (7). to be applied. After vkT2 hours have passed after the application of the pulse voltage has ended, the switch (9) is set to the resistance meter α.
1) can be switched to the side.

After another 73 hours, the pNAB-Lm@ signal is released and the next voltage application becomes possible. The resistance value is measured during time T3, and the measurement result is sent to the calculation section (2). In the calculation section (2), apr and rα■ compare the measured values with the previous measured values. If the measured value is not within a certain range based on the previous measurement value, it is determined that there is a contact failure.

There are various ways to set a certain range, but the simplest method is to compare the value to see if it is higher than the previous measured value. Below, we will discuss the case of this method as an example. If a value higher than the previous measurement value is obtained, O
The Fσα committee does not use this measurement value, but uses a blobbing device (
6), the probe is released from contact with the thermal head (7) to be measured, and a reprobe signal is sent to bring it into contact again. Then, the resistance value is measured again. As can be understood from Figure 1, it is impossible for the resistance value to increase due to the application of a voltage pulse, and if it does increase, it is likely due to poor contact of the probe. It is.

In this case, if the probe contacts the same point again, there is a possibility that the probe will contact again. Therefore, re-contact is performed not at the previous location but at a location a little further away. The probe makes contact at a point called a pad provided at the end of the lead wire, but makes contact again at a slightly distant location within the same pad.

If the measured resistance value is lower than the previous measured value, the CPU α→ adopts this measured value and compares it with the adjustment target value R. If it reaches R8 or below and does not reach l/-1 (3PUαrei KNABL
R: After the signal ゛ is released, the set value of the peak value of the voltage pulse to be applied ■ θ is increased by ΔV and given to the pulse generation circuit (to), and then the start signal S for applying the next voltage pulse Generate TART.

In this way, the resistance value of the heating resistor is decreased while gradually increasing the peak value of the applied voltage pulse. The resistance value is v! If it is less than or equal to the target value R8, the adjustment of the resistance value of the heating resistor is completed.

Time limit T1. T2. T3 is provided by the switch (9)
This is to avoid the influence of chattering in the relay network (8). Even if a voltage pulse is generated from the pulse generating circuit αO before the switch (9) and relay network (8) are completely switched, the pulse will not be applied to the thermal head (7). In addition, a switch (9), a relay network (
Even if the resistance value is measured before 8) is completely switched, accurate measurement cannot be made.

The voltage pulse to be applied may be a single pulse, but
Rather, it is easier to control by applying a pulse group consisting of several pulses. The energy of the voltage pulse is defined by the peak value and the pulse width Δt, but if this becomes too large, the heating resistor will be destroyed. Therefore, if the energy of the voltage pulse is at a certain level and there is a risk of destroying the heating resistor, the pulse width must be adjusted to decrease according to the peak value of the voltage pulse. Rather than adjusting the pulse width of a single pulse, the width Δt of each pulse in a group of pulses is kept constant;
It is easier to adjust the ratio Δt/'r between the pulse period T and the pulse width Δt to a value that does not destroy the heating resistor, taking into account the change in the peak value. Alternatively, Δt/'r may be kept constant and the number n of pulses constituting the pulse group may be changed according to changes in the peak value. If the energy of the voltage pulse is sufficiently small, a single pulse or a group of pulses may be applied at intervals of b.

When the peak value of the applied voltage pulse is low, the phenomenon that the resistance value decreases is no longer observed. Therefore, the first voltage pulse application is started from a peak value at which a decrease in resistance value can be expected. V in Figure 1. indicates the peak value of the first applied voltage pulse.

The adjustment target resistance value R8 and the number of pulses n are changed using the keyboard M. Resistance value after adjustment and crtr(t
The calculation result of step 4 is outputted to the printer αη.

FIG. 6 is a flowchart of a method for adjusting the resistance value of a heating resistor using the apparatus shown in FIG. 4.

In step (1), pulse conditions such as the peak value Va and the number of pulses n are initialized. Next, in step, the blowing device (6) blows the thermal head (7) and the relay network (8) is switched.

Thereafter, in steps (to) and (c), n pulse trains having the set peak value are applied, and the resistance value is measured.

Step (c) to compare the current measurement value with the previous measurement value.
If the measured value is larger than the previous measurement, perform probing again at step (to). If it is smaller than the previous measurement value, a comparison with the adjustment target resistance value R0 is performed in step (a). If the measured value is R6 or less, the adjustment for that heating resistor is completed. If it is not below R0, the peak value of the applied voltage pulse is increased by ΔV and a pulse is applied (step @).

In principle, adjustment is continued in this manner until the measured value becomes R8 or less. However, there are some unique elements whose resistance value does not decrease no matter how much pulse voltage is applied. Furthermore, there is a limit to the peak value of the pulse voltage that the pulse generating circuit αQ can generate. Therefore, even if the resistance value does not become R6 or less, the adjustment is terminated when the number of pulse voltage applications reaches a certain number. Step (c) is provided for this purpose.

It has already been described in FIGS. 2 and 3 that the resistance value is measured using several heating resistors as a group.

When the adjustment for one group is completed, apσα→ becomes the average value.

Calculation ΣR0ΣR2 is performed to obtain the standard deviation. And printer αη is the maximum value and average value of one group.

The minimum value is printed as shown in FIG. When all the heating resistances of the thermal head are adjusted, CPσQ4 calculates the standard deviation σ. The result is output to the printer αη.

FIG. 7 is a detailed explanatory diagram of the pulse generating circuit αO of FIG. 4. In the figure, (1) 0, (I), (to) are flip-flop circuits, G1), (A), (42 are timer circuits,
(To) is a pulse generator, (To) is a monostable multicircuit, (
(to) is a transistor, (b) is a voltage power supply, (to) is a counter, and (to) is a comparator.

When the start signal 5TART @ is received from the calculation unit (2), the flip-flop circuit 00. (goods) are set.

FlfNA from the flip-flop circuit (to) to the calculation section
A BLE signal is sent. While the ENABLE signal continues, changes in the peak value signal Vθ and generation of the 5TART signal are prohibited. The coil (91) of the switch (9) is energized by the output of the flip-flop circuit, and the contact (92)
.

(93) is switched to the opposite side as shown. The timer circuit OD outputs an output T1 time after the flip-flop circuit (to) is set. As a result, when the flip-flop circuit (TO) is set, the gate (TO) is opened, and the pulses generated by the pulse generator (TO) are given to the monostable multi-circuit (TO). The monostable multicircuit shapes the pulse width of the pulse generator into a pulse having a desired pulse width Δt. Δt is determined by the resistors and capacitors in the monostable multicircuit. FIG. 8 shows the output pulse waveform of the pulse generator (to) and the output waveform of the monostable multi-circuit (to).

The pulse of the monostable multi-circuit (to) supplies the gate drive current of the transistor (to), and the transistor (to) is in an ON state for a period Δt during which the pulse exists.

While the transistor (to) is in the ON state, the voltage power supply (b)
The output voltage of the switch (9) contacts (92), (93)
, is applied to the sample via a relay network (8). The peak value of the voltage power supply (b) is the peak value example % v from the calculation unit (2)
It is determined by s.

Pulses passing through gate (2) are counted by a counter (to). The count value of the counter (to) is compared with the number n given from the calculation section (6) by the comparator (to).

When the count value reaches n, the flip-flop circuit (to) is reset by the output of the comparator (to). This closes the gate and ends the application of one pulse voltage to the sample.

The output of the comparator (to) is also given to the timer circuit.

The timer circuit (G) outputs an output after 2 in the time limit, which resets the 7 lip flop (to) and switches (9).
) is switched to resistance measurement. When the switch (9) is switched, the contacts (92) and (93) are switched to the positions shown, and the resistance value of the heating resistor of the sample is measured by the resistance meter (b).

When 13 hours have elapsed since the timer circuit (2) outputs, the timer circuit (6) outputs an output, which resets the flip-flop circuit (7), the θ terminal output becomes XIHL/level, and the ENABLE signal disappears. This allows the application of the next voltage pulse.

An example of the experimental results of resistance value changes according to the present invention is as follows:
If the present invention is not carried out, the absolute value is ±20 inches and the standard deviation σ is 5.6%, whereas when the present invention is implemented, the absolute value is ±3 inches and the standard deviation is 0.4 inches. The variation in resistance values has been significantly improved.

This made it possible to almost eliminate density unevenness in printing by the thermal head.

The inventors set the initial setting value of the peak value of the voltage pulse applied to adjust the resistance value (Fig. 1 ■) to several tens of v1, and the increment ΔV for each applied pulse voltage to 1 vn'zlo ~ 20 ．．
The resistance value of the heating element was adjusted by setting the width of one pulse Δt to 1 to several microseconds and the pulse interval to several tens of microseconds.

The inventors adjusted the resistance value by setting the time limit TT to around 10 msec and the time limit T2 to several msec.

It goes without saying that the specific numerical values of the parameters used for adjusting the resistance value are not limited to the example described above, and can take various numerical values within the range that produces the effects of the present invention.

In step (c) of Fig. 6, the magnitude is compared with the previous resistance measurement value, but instead of this, the resistance measurement value is compared to the previous resistance measurement value within a certain range, for example, 0.9 to 1.0. It is also possible to check whether it is within the double range, and re-measure the resistance value if it is not within this range.

An example of an apparatus for carrying out the method of manufacturing a thermal head according to the present invention is shown in FIGS. 4 and 7, but the present invention is not limited thereto.

The pulse height [Vs] of the pulse voltage and the number of pulses n are automatically given to the pulse generation circuit αO from the calculation unit (to), but these can also be set manually. This can be easily implemented by providing the pulse generation circuit with a switch for setting the peak value Vs and the number of pulses n. Further, both automatic setting from the calculation section (2) and manual operation may be used together.

In the example of FIG. 7, the switch (9) is a relay that energizes the coil (91) to drive the contacts (92) and (93), but it is also possible to use a thyristor switch instead.

〔Effect of the invention〕

In the method for producing a thermal head according to the present invention, a voltage pulse is applied to the heating resistor to reduce the resistance value, thereby reducing variations in the resistance value of the heating resistor of the thermal head. Unevenness in print density can be significantly reduced.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the principle of the thermal head manufacturing method according to the present invention, and Figs. 2 and 3 show the resistance values when the thermal head manufacturing method according to the present invention is not carried out and when it is carried out. FIG. 4 is a diagram showing the distribution, FIG. 4 is a groove diagram showing an embodiment of the apparatus for carrying out the method of manufacturing a thermal head according to the present invention, FIG. 5 is a waveform diagram of the main part of FIG. 4, and FIG. A film configuration diagram showing one implementation procedure of the method for manufacturing a thermal head according to the present invention, FIG. 10 is a diagram explaining the usage state of the thermal head in a thermal recording device, and FIG. 11 shows the resistance value of a general thermal head. It is a figure showing an example of distribution. In the figure, (1) is an insulated substrate, (2) is a lead wire, (
3) is a heating resistance element, (6) is a probing device, and (7) is a probing device.
) is the thermal head, (8) is the relay network, (9) is the switch, αO is the pulse residual circuit, α force is the resistance meter, @ is the calculation section, α → bcpσ, an, m, (42 is the timer circuit, (to) is a pulse generator, (to) is a monostable multi-circuit, (b) is a voltage power supply, (to) is a counter, and (to) is a comparator. Note that the same symbols in each figure are the same. Figure 1 Figure 2 Figure 3 Figure 3 Direct payment Figure 4 Figure 5 Figure 8 Figure 6 Figure 7 (Continued from page 1) Inventor Village 1 ) Yukio 1-1, Tsukaguchi-honmachi 8-chome Seisakusho, Amagasaki City Mitsubishi Electric Co., Ltd. Communication equipment procedural amendment (voluntary) 28 Name of invention Method for manufacturing thermal head 3, To the person making the amendment Representative Hitoshi Katayama Part 5, Subject of amendment (1) Detailed description of the invention in the specification (21 Drawing 6 Contents of amendment (1) 'MIS (Meta
l-Insulator-8emiconductor
), 'MIM (Metal-In
sulator-Metal). ' on page 20, line 7, page 22, line 8, and page 22, line 8.
ENABLE, 'ENABLE' is prohibited. I am corrected. (3) r is given in the details @ page 13, line 17. 1 is given for ``Yo''. Here, use the resistance meter αJ.
Then, the resistance value of the heating resistor element of the thermal head (7) is measured. As mentioned above, a voltage pulse is applied only when the resistance value is greater than a predetermined value Ro. Correct it to 1. (4) Details @ 1 on page 18, line 11 1 After that, the resistance value is measured in step 1 (to). Compare the measured value with the predetermined value Ro in the step fight, and the resistance value is R.
When it is smaller than 8, no voltage pulse is applied. If the resistance value is greater than R8, correct it to 1. (5) 1 switch on page 24, line 8 of specification 4.
Correct the statement to read 1 semiconductor switch. (6) Figure 5 is corrected as shown in the attached sheet. (7) Figure 6 is corrected as shown in the attached sheet. 7 List of attached documents (υFigure 5 1 copy (2) No. 6
Figure 5 above

Claims (3)

[Claims] (1) Measure the resistance value of the heating resistor of the thermal head,
1. A method for manufacturing a thermal head, comprising applying a voltage pulse to a heating resistor whose resistance value is greater than a predetermined value to reduce the resistance value to a predetermined value or less. (2) The method for manufacturing a thermal head according to claim 1, wherein the voltage pulse is a single pulse. (3) The method for manufacturing a thermal head according to claim 1, wherein the voltage pulse is a pulse group consisting of a plurality of pulses.