JPS6183058A - Apparatus for preparing thermal head - Google Patents

Abstract

PURPOSE:To successively lower the resistance value of a heat generating resistor, by mounting a pulse generation circuit and a resistance meter and applying a peak value higher than the preceding one to a heat generating resistor from the pulse generation circuit by a calculation part when the resistance value, after a voltage pulse was applied, is equal to or more than a predetermined value. CONSTITUTION:The peak value Vs of apply voltage, the set signal of the numbers (n) of pulses ad a START signal are applied to a pulse generation circuit 10 form a calculation part 12. After the above mentioned set pulse is applied to a thermal head 7, of which the resistance value is equal to or more than a predetermined value R0, from the above mentioned circuit 10, the resistance value thereof is measured by a resistance meter 11. Because the resistance value of a heat generating resistor is not lowered when the peak value of a voltage pulse is low, the above mentioned measured value is sent to the calculation part 12 and compared with the preceding measured one by CPU14 and, when the lately resistance value is low and higher than the predetermined value R0, the peak value Vs is set so as to be made high by DELTAV and a voltage pulse is applied to the above mentioned thermal head 7 from the pulse generation circuit 10. By this method, the resistance value of the heat generating resistor is gradually lowered to the predetermined value R0 or less to eliminate irregularity.

Description

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

[Conventional technology]

It does not require development or fixing, is noiseless, maintenance-free, and has high reliability.Thermal recording paper has become popular with the improvement of thermal recording paper. In thermal recording, a recording current is applied to a resistor provided on a substrate.

This technology utilizes the Joule heat generated by the current flowing through the resistor to color the thermal paper in contact with the resistor, melts the ink layer of the thermal transfer paper, and prints and records recorded signal information on the transferred paper. It is.

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

The thermal head is mounted on an insulating substrate (1) with A/', Au
The heating element is composed of a lead part (2) made of a good electrically conductive material such as Qu, etc. by film-forming technology, and a film-like element resistor (3) connected to both ends of the lead part (2).

An alumina ceramic substrate is often used as the material for the insulating substrate (1), or an alumina ceramic substrate is used for the glaze layer. In the case of a thin film method as the material for the element resistor (3) +! TatN + Ta-8i0. , Ta-8t
, Ni-0uTi, 03, etc. are used.

In the case of a thick film method, an oxide of a noble metal such as itO or PtO is mixed with a glass material, applied and sintered.

Although not shown, after forming the element resistor (3), a glass film for protecting it is fired.

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 absorbed by the A of the recording device configured as shown in Figure 10.
The light is transmitted to the thermal paper (5) at a certain portion, 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 is low/I/(4)
Indicates the pressing direction.

Generally, in a thermal head for facsimile, for example, about 2000 resistors are independently arranged in parallel as heating/resistive elements per head. These heating resistors have a surface temperature of 250°C to 60°C due to their Joule heat.
It is heated to about 0° C., and the applied energy equivalent to reaching this temperature is required to be about 0.2 mJ (joule) to 2 mJ, although it varies depending on the resolution of each thermal head.

Conventionally, there have been three types of thermal heads: thick-film type, thin-film type, and semiconductor type, depending on the manufacturing process and material of the resistor. For the thick film type, a desired pattern is formed in advance on a screen or photoresist film using a paste-like resistive material, the resistive material is printed or embedded using screen printing technology, and is fired as a post-process to generate heat. A 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 into 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 is used.

Of the above eight manufacturing methods, the ones that have been put into practical use are the thick film type and the thin film type. By the way, although the manufacturing process of the thin film type is extensive, it has the great advantage that there is little variation in the resistance value of the heating resistor and that fine patterns can be formed. On the other hand, the thick 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. Thermosensitive recording is determined by the resistance value of a resistor and uses the generated Joule heat, so variations in resistance value naturally cause density unevenness in the quality of the image printed thereon.

FIG. 11 shows an example of the resistance value R+ -R1 of each element resistor constituting the thermal head, . . . islands.

Normally, the resistance value variation of thin-film type is uniform within ±5 inches to ±16%, while that of thick-film type is uniform within ±15 inches to ±8%.
The reason why it has become popular even though it is inferior to the thin film type is that it has great advantages such as high reliability represented by overload power and wear resistance, and low cost. That's why. Recently, it has become possible to form fine patterns with thick film types as well as with thin film types. For example, in forming a conductor pattern, a printed film thickness of 8 μm or more is conventionally required, but a conductor film thickness of 13000 Å or less can also be formed. This advantage is due to the fact that the etching factor during photoetching is 1, that is, almost zero, which is the same as that of the thin film type, compared to the conventional etching factor of 20 μm. On the other hand, in order to improve the variation in the resistance value of thick film types, in addition to improving conventional screen printing technology such as improving mesh screens and metal mask screens, for example, thick film resistors described in Japanese Patent Publication No. 59-22675 Photo-etching of the body
There is a method of embedding a thick film resistor in a photoresist pattern as described in Japanese Patent Laid-open No. 18506, and a method of surface polishing a thick film resistor as described in Japanese Patent Laid-Open No. 54-99448. Furthermore, as described in 1975-475971, there is a thin film conductor with a thick film resistor printed on it. These attempts are to make the shape of the heating resistor uniform and to improve the variation in resistance value caused by this effect.

Further, progress has been made in improving thick film resistor materials.

As a thick film resistive material, for example, Japanese Patent Application Laid-Open No. 58-954
4 and JP-A No. 58-9543, p-tenium oxide, high melting point frit glass, zirconium oxide, etc. are suitable. However, these improvements were mainly made to maintain reliability as a thick-film thermal head, and did not improve the variation in heating resistance values.

By the way, if the shape of a thick film resistor is geometrically arranged to be the same as that of a thin film resistor, there is a question as to whether the variation in resistance value will really be the same as that of a thin film resistor. Theoretically, the resistance value of the resistor is expressed by the following equation.

R=ρ・□(Ω) w”t Here, ρ: Specific resistance of the resistor (Ω-crIL) l!: Length of the resistor cIrL) W: Width of the resistor (crrL) t: Resistance of the resistor Thickness (cIrL) Screen-printed heating resistors usually have the length of the resistor (I), the width of the resistor (B), and the thickness of the resistor (1).
Both vary slightly, but ultimately the problem is that the thick film resistor material basically maintains a certain particle size, μ-tenium oxide, and glass frit! This is the variation in the resistivity itself of the resistor caused by the difference in the degree of bonding that occurs during firing of zirconium oxide, etc., and the resulting variation in the resistance value. This problem cannot be solved by strict screen printing and firing conditions in the thick film manufacturing process, and even by improving the heat generating resistors before and after the manufacturing process.1 This is because the particle size of ruthenium oxide, etc. As stated in 1982-9544, the size is 6 μm, which cannot be ignored, and the determination of the resistance value of a thick film resistor is mainly based on the M of the contact interface with the p-thenium oxide glass frit.
This is because the cause is ultimately due to the heterogeneous bonding state of e's-Me (me, ri μm insulator meta/1/). Basically, the reason why the resistance value of thick film resistive materials changes significantly even though the firing temperature, atmosphere, and firing speed are the same is presumed to be because the bonding state of M, -I, and -M changes. can.

Therefore, thick film resistive materials such as ruthenium oxide and glass 7 lithium oxide, which have finer grain sizes, have recently become commercially available. However, the desired effect was not achieved.

From the above, it can be seen that unless the variation in thick film resistance due to non-uniformity of the contact interface is improved, the variation in resistance value will not be improved. In order to improve variations in resistors, laser trimming and the like have been used to adjust resistance values mainly on thick film circuit boards, thin film circuit boards, and the like. Also, JP-A-58-786
In the liquid jet recording head described in No.
The resistance value is adjusted to match the heat 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 dynamic movement of the rotating roller that is located on the heating resistor and presses the thermal paper. In addition, since 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 can deteriorate the performance of the thermal head due to changes in shape. Couldn't use it.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus for manufacturing a thick-film thermal head by changing its resistance value without changing the shape of the heating resistor.

[Means for solving problems]

The present invention reduces the resistance value by applying a voltage pulse whose peak value gradually increases to the heating resistor of the thermal head using a pulse generating circuit, thereby reducing the variation in resistance. A resistance meter is also provided to measure the resistance value of the heating resistor.

[Effect]

In the present invention, by utilizing the fact that the resistance value of the heating resistor decreases by applying a voltage pulse, it is possible to significantly reduce variations in the resistance value. As a result, density unevenness in the print quality of the thermal head can be significantly reduced.

[Embodiments of the invention]

The present invention implements a process to reduce the resistance of the heating resistor after the main production process.

That is, after forming a heating resistor, a lead wire, and a protective galanic film on a substrate, a process of reducing the resistance value is performed using the apparatus of the present invention.

FIG. 1 is a diagram showing the principle of a production method for reducing the resistance value of a heating resistor to reduce variations.

This invention utilizes the phenomenon that when a voltage is applied to a thick film resistor, the resistance value decreases. This phenomenon is M
(Metal-Insulator-Meta
l) A thick film resistor insulator with a structure (In5ulat
It is also believed that this is because p- breaks down due to voltage.

In any case, it is certain that the physical properties of the resistor change due to the application of voltage.

FIG. 1 shows the case where the resistance value of the heating resistor whose initial resistance value is R11R3 is adjusted to approximately 0.

First, the resistance value of each heating resistor is measured and compared with the target resistance value. No voltage pulse is applied to a heating resistor, such as a tow, which has a resistance value lower than that of a horse. resistance value A larger than that of 4. Apply a voltage pulse to the heating resistor with the bird.

First, a voltage pulse whose peak value is initially set to vo is applied to reduce the resistance value. The resistance value after the decrease is measured, and if the value is greater than or equal to 100%, a voltage pulse with a peak value of vo+ΔV is applied. Thereafter, the resistance value is measured, and if the resistance value is equal to or greater than the resistance value, a voltage pulse having a peak value of v0+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 below the horse's height.

Once the resistance value is below the horse's height, the adjustment ends there.

In this way, the resistance value of the heating element is made to be within a certain range under the horse's body. Since the purpose of the present invention is to reduce the variation in resistance value, it is not only necessary that the resistance value be below the horse's length, but it is necessary that the resistance value be within a certain range below the horse's length. Therefore, the resistance value is gradually decreased and stopped when it becomes 4 or less.

FIGS. 2 and 8 are diagrams showing the distribution of resistance values of heating resistors when the manufacturing method of making the resistance values uniform using the apparatus of the present invention is not performed and when it is performed. A number of heating resistors are grouped into a - 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, there is almost no variation.

FIG. 4 is a configuration diagram showing an example of the apparatus of the present invention. FIG. 5 is a waveform diagram of the main signals in FIG. 4.

(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 The switch that switches between resistance measurement and QO is the pulse generation circuit that generates the adjustment voltage pulse. (hereinafter referred to as CPU), (to) is memory, QO is keyboard, and an is printer.

The procedure for reducing the resistance value using the device of the present invention will be explained.

A setting signal for the peak value Vs 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. Here, the resistance value is measured, and the following process is performed for heating resistors having a resistance value greater than the target resistance value. When receiving the voltage application start signal 5TART from the calculation section, the pulse generation circuit QG turns ENABL.
E-inhibit signal is sent back to the calculation section. In addition, the switch (9) is switched to the pulse generation circuit (1G side). During the period when the ENABLE prohibition signal is output, the pulse height value VS is changed and the 5T
Generation of the ART signal is prohibited. This means that the peak value VS should not be changed while the voltage pulse is being applied.
Also, the start signal 8TART for applying the next voltage pulse should not be issued until the application of the current voltage pulse is finished. n pulses are applied to the heating resistor of the thermal head (7) via the switch (9) and the relay network (8). After 12 hours have passed after the application of the pulse voltage is finished, the switch (9) is switched to the resistance meter (b) side. After another 13 hours, the ENABLE prohibition signal is canceled and the next voltage application becomes possible. The resistance value is measured during time T3,
The measurement results are sent to the calculation section (2). In the calculation section @, the CPU α→ compares the measured value with the previous measured value.

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.

The case of this method will be described below as an example.

If a higher value than the previous measurement is obtained, then C
The PU (14) does not use this measurement value, but sends a reprobe signal to the probing device (6) to release the probe from the thermal head (7) to be measured and recontact it.Then, the resistance value As can be understood from Figure 1, it is impossible for the resistance value to increase due to the application of the voltage pulse, and if it does increase, it is due to the contact of the probe. This is because it is thought to be caused by a defect.

In this case, the probe re-contacts, but if it re-contacts the same location as before, there is a possibility that the contact will be defective again. Therefore, re-contact is performed not at the previous location but at a location a little further away. Contact with probe 1 is made at a place called a pad provided at the end of the lead wire, but re-contact is made at a slightly distant position within the same pad.

If the measured resistance value is lower than the previous measured value, the CPU α uses this measured value and compares it with the adjustment target value. If it has not reached the height of the horse's body, after the ENABLE prohibition signal is released, the CPU α4 increases the set value VS of the peak value of the voltage pulse to be applied by Δ■ and gives it to the pulse generation circuit QG.
A start signal 5TART for applying the next voltage pulse is generated.

In this way, the resistance value of the heating resistor is decreased while gradually increasing the peak value of the applied voltage pulse. When the resistance value falls below the adjustment target value, the adjustment of the resistance value of the heating resistor ends. This is to avoid the influence of chattering in the connected circuit. The switch (9) is connected to the pulse generation circuit aO side, and the relay network (8)
Even if a voltage pulse is generated from the pulse generating circuit QO before it is completely switched to select the - heating resistor, the pulse will not be applied to the thermal head (7).

Also, after applying the voltage pulse, the switch (9) switches the resistance meter αυ
Even if you measure the resistance value before it is completely switched to the side, you will not be able to get an accurate measurement. The reason why the time limit Tt is provided is that it takes time for the voltage pulse to completely disappear, so switching the switch (9) during that time is prohibited. The voltage pulse to be applied may be a single pulse, but it is easier to control it if it is applied as a group 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, when the voltage pulse has a certain amount of energy and there is a risk of destroying the heating resistor, the pulse width must be adjusted to decrease in accordance with the peak value of the voltage pulse. Rather than adjusting the pulse width of a single pulse, the width Δt of each pass/V in a pulse group consisting of multiple pulses is kept constant, and the ratio Δt/T of the pulse ti1 period T to the pulse width Δt is It is easier to adjust the value to a value that does not destroy the heating resistor in response to changes in the peak value. Alternatively, by keeping Δt/T constant,
Changes in peak value (accordingly, the number n of pulses constituting the pulse group may be changed.If the energy of the voltage pulse is sufficiently small, it may be applied as either a single pulse or a group of pulses.

When the peak value of the applied voltage pulse is low, the phenomenon that the resistance value decreases is no longer observed. Therefore, it is advantageous to start applying the first voltage pulse from a peak value at which a decrease in resistance value can be expected. vo in FIG. 1 indicates the peak value of such a first applied voltage pulse.

Change the adjustment target resistance value Ro and the number of pulses n using the keyboard Q! This is done using S. The adjusted resistance value and the calculation result of 4 to the CPU are outputted to the printer aη.

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 Vs and the number of pulses n are initialized. Next, in step Qp, the blowing device (6) blows the thermal head (7) and switches the relay network (8).

Next, in step -, the resistance value is measured. Step (51
In step 1, the measured value is compared with the target value, and if it is smaller than the target value, the application of the voltage pulse group is not compromised. When the resistance value is larger than the resistance value, in step 4 (2), n pulse trains having the set peak value are applied and the resistance value is measured. Compare the current measurement value with the previous measurement value at step (c). If the dog is a dog than the previous measurement value, perform blobbing again at step (to). If it is smaller than the previous measurement value, set the adjustment target. Comparison with resistance value salt is performed using step wire. If the measured value is below the pumping point, the adjustment for that heating resistor is completed. If it is not 80 or less, the peak value of the applied voltage pulse is increased by Δ■ and a pulse is applied (step @).

In this way, adjustment is basically continued until the measured value is below B0. 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 can be generated by the pulse generating circuit head. Therefore, even if the resistance value does not become below the horse's height, 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 8 that the resistance value is measured using several heating resistors as a group.

When the adjustment for one group is completed, the CPU α executes calculations Σ几 and ΣK to obtain the average value and standard deviation. Then, the maximum value, average value, and minimum value of the graph of printer α are printed as shown in FIG. - When all the heating resistances of the thermal heads have been adjusted, OP U H calculates the overall average value and the standard deviation σ. The results will be published on Printermino.

FIG. 7 is a detailed explanatory diagram of the pulse generating circuit QQ of FIG. 4. In the figure, (7), (to), country H is a flip-flop circuit 0υ, seagull, (b) is a timer circuit, princess is a pulse generator, (to) is a monostable multi-circuit, country is a transistor, (ro) ) is the voltage power supply, (to) is the counter, and (to) is the comparator.

When receiving the start signal 8TART signal from the calculation section (to),
The flip-flop circuits ZENG and ＠罎 are set. An ENABLE prohibition signal is sent from the flip-flop circuit (to) to the calculation section. While the ENABLE prohibition signal continues, changes in the peak value signal Vs and generation of the 5TART signal are prohibited. The output of the flip-flop circuit K141 energizes the coil /l/@11 of the switch (9), and the contact -
.

(gl is switched to the opposite side from the diagram. After T1 time after the flip-flop circuit is set, the timer circuit O
p outputs. This results in a flip-flop circuit (to)
When is set, the gate (2) is opened and the pulses generated by the pulse generator (to) are given to the monostable multicircuit μs. The monostable multi-circuit converts the pulse width of the pulse generator into a pulse with the desired pulse width Δatt-mo. Δt is determined by the resistors and capacitors in the monostable multicircuit. FIG. 8 shows the pulse waveform of the pulse generator and the output waveform of the monostable multicircuit CF9.

The pulse of the monostable multi-circuit supplies the gate drive current of the transistor, and the transistor is in an ON state for a period Δt during which the pulse exists. While the transistor □□□ is in the ON state, an output voltage in the form of a voltage source is applied to the sample p via the contact point of the switch (9), H,') relay network (8). The peak value of the voltage power source C3710 is determined by the peak value signal VS from the calculation section (2).

Pulses passing through the gate field are counted by a counter. The count value of the counter is compared by a comparator (391) with the number n given from the calculation section (product).

When the count value reaches n, the flip-flop circuit (to) is reset by the output of the comparative countries. This closes the example 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 quantity.

After the time limit T2, the timer circuit outputs 7 due to the heat.
Lip 70 knob (to) is reset and switch (9)
is switched to resistance measurement. When the switch (9) is switched, the contacts -, - are switched to the positions shown in the figure, and the resistance value of the heating resistor of the sample is measured with a resistance meter.

When 13 hours have elapsed since timer circuit f41 outputs, timer circuit [2 outputs, which resets the flip-flop circuit (to) and the Q terminal output becomes lH ruberto, and the ENABLE inhibit 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:
When the present invention is not implemented, the absolute value within one thermal head is ±20 degrees and the standard deviation σ is 5.6%, whereas when the present invention is implemented, the absolute value is ±8% and the standard deviation is 0. ．．
The variation in resistance values has been improved to a wide range of 4%. This made it possible to almost eliminate density unevenness in printing by the thermal head.

The inventors set the initial setting value (Vo in Figure 1) of the peak value of the voltage pulse applied to adjust the resistance value to several tens of square meters, and set the increment ΔV of the applied pulse voltage every time to IV to several volts 11 times. The number of pulses n included in the voltage application is 10 to 20.1, the pulse width Δt is 1 μ to several μ seconds, and the pulse interval is several tens of μ.
The resistance value of the heating element was adjusted in seconds.

The inventors adjusted the resistance values by setting the time limits T and T3 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 that various numerical values may be used within the range that produces the effects of the present invention.

In step (c) of FIG. 6, the resistance measurement value of the turn is compared in size, 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. It is also possible to check whether the resistance value is within the range of 0 times or not, and to re-measure the resistance value if it is not within this range.

An example of the thermal head manufacturing apparatus according to the present invention is shown in the fourth example.
Although shown in FIG. 7, the present invention is not limited thereto.

Although the peak value VS of the pulse voltage and the number of pulses n are automatically given to the pulse generation circuit αG from the calculation unit @, it is also possible to set these 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/L'@ll to drive the contacts 61121 and +931, but it is also possible to use a semiconductor switch instead.

[Effects of the Invention] The thermal head manufacturing apparatus according to the present invention applies a voltage pulse whose peak value gradually increases to the heating resistor to reduce the resistance value, so that the resistance of the heating resistor of the thermal head is reduced. By reducing the variation in values, it is possible to significantly reduce the unevenness of print density of the thermal head.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the principle of a method for manufacturing a thermal head with little variation in resistance value, and FIG. 2 and FIG. , FIG. 4 is a configuration diagram showing an embodiment of the thermal head manufacturing apparatus according to the present invention, FIG. 5 is a waveform diagram of the main part of FIG. 4, and FIG. 6 is a flowchart showing one implementation procedure of the manufacturing process by the thermal head manufacturing apparatus according to the present invention, FIG. 7 is a detailed configuration diagram of the Hullless generation circuit shown in FIG. 4, and FIG. 8 is an explanation of the waveforms shown in FIG. 7. Figure 9 is a general diagram of a thermal head, Figure 10 is a diagram explaining how a thermal head is used in a thermal recording device, and Figure 11 is an example of the distribution of resistance values in a general thermal head. It is a diagram. In the figure, (1) is an insulated substrate, (2) is a lead wire, (
3) is a heating resistance element, (6) is a blobbing device, (7
) is the thermal head, (8) is the relay network, (9) is the switch, αG is the pulse generation circuit, (b) is the resistance meter, mackerel is the calculation section, αsun is the OPU, (3υ, seagull), (6) is the Timer circuit, eel is pulse generator, (to) is monostable multi circuit, mouth η
is the voltage source, (to) is the counter, and country is the comparator. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] A pulse generating circuit applies a voltage pulse to a heating resistor of a thermal head, and a resistance meter measures a resistance value of the heating resistor, and the resistance measurement value of the heating resistor after applying the voltage pulse is equal to or higher than a predetermined value. In the thermal head manufacturing apparatus, the pulse generating circuit applies a voltage pulse having a higher peak value than the previous one to the heating resistor.