JPS6183062A - Thermal head manufacturing equipment - Google Patents

Abstract

PURPOSE:To easily grasp the reduction degree of the irregularity in a resistance value, by mounting a pulse generation circuit and a resistance meter while providing a calculation part to calculate the average value or standard deviation of the resistance value of a heat generating resistor. CONSTITUTION:A voltage pulse is applied to the heat generating resistor of a thermal head 7 from a pulse generation circuit 10 on the basis of the set signal of a peak value Vs and the number (n) of pulses by a calculation part 12. At this time, said voltage pulse is applied to the heat generating resistor, of which the resistance value is larger than an objective resistance R0, in one group of heat generating resistors. The preceding resistance value is compared with the lately resistance value and, when the lately resistance value is low and higher than the objective resistance value R0, the peak value Vs is made further high by DELTAV to adjust said lately resistance value to the objective resistance value R0 or less. When the adjustment of one group is finished by this method, CPU14 calculates an average value and standard deviation. When the adjustment with respect to all heat generating resistors of one thermal head 7 is finished, CPU14 calculates the average value and standard deviation sigmaof the whole and displays the result thereof on a printer 17.

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.

[Traditional alchemy]

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

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

The thermal head is made of AJ, Au, and Cu on an insulating substrate (1).
The heating element is composed of a lead part (2) made of a good electrically conductive material such as a film-forming element resistor (3) formed by film-forming technology, and a film-like element resistor (3) connected to the lead part (2) 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.For the material of the element resistor (3), in the case of a thin film type, Ta2Ne Ta-5i02. Ta-5i, N
A material such as i-CuT + 20B is used.

In the case of a thick film method, an oxide of a noble metal such as Ru2O 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 section of this thermal head for a fixed period of time, heat is generated in the resistor section due to sew heat. This heat is absorbed by the A of the recording device configured as shown in Figure 1θ.
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 rho/l' (4
) indicates the pressing direction.

Generally, in a thermal head for facsimile, for example, each head has about 2000 resistors arranged independently in parallel as heating resistors. These heat generating resistors have a surface temperature of 250°C to 6°C due to their juicy heat.
The applied energy equivalent to reaching this temperature is approximately 0.2 mL (joule/I/) to 2 m, depending on the resolution of each thermal head.
J is required.

Conventionally, there have been three types of thermal heads: a thick film type, a thin film type, and a 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, tank μ-thread material is mainly vapor-deposited or sputtered to form a basic pattern that can become a resistor in advance, 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.

(1) Among the 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 utilizes the generated heat, so variations in resistance value naturally cause density unevenness in the image printed thereon.

FIG. 11 shows an example of resistance values R1, R2, . . . Rn of each element resistor constituting the thermal head.

Normally, the resistance value variation of thin film type is uniform within ±5% to ±15%, while that of thick film type is uniform between ±15% to ±8.
The reason why it is widely used 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 was conventionally required, but a conductor film thickness of 8000 Å or less can also be formed. This advantage is due to the fact that the etching factor during photoetching is about the same as that of the thin film type, ie, almost zero, compared to the conventional method that required an etching factor of 20 μm.

- In order to improve the variation in the resistance value of thick film blades, in addition to improving conventional screen printing technology such as improving mesh screens and metal mask screens, for example, thick film Photoetching of resistors, method of embedding thick film resistors in photoresist patterns as described in Japanese Patent Publication No. 57-18506, and surface polishing of thick film resistors as described in Japanese Patent Application Laid-open No. 54-99448. There are ways to process it. In addition, there is one in which a thick film resistor is printed on a thin film conductor, as described in 1984-47597. These attempts are to make the shape of the heating resistor uniform and to improve the variation in resistance value due to the effect Iζ.

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
Ruthenium oxide, high melting point frit glass, zirconium oxide, etc. described in No. 4 and JP-A No. 58-9548 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 the same as that of a thin film resistor, there is a question as to whether the variation in resistance value will actually be the same as that of a thin film resistor. Theoretically, the resistance value of the resistor is expressed by the following equation.

Here, e: Specific resistance of the resistor (Ω-:) l: Length of the resistor (an) W: Width of the resistor (ao) t: Thickness of the resistor (b) Screen-printed heating resistor is usually its low resistance
The length l), the width of the resistor (W), and the thickness of the resistor (1) all vary slightly, but ultimately (the problem is that the thick film resistor material basically has a grain size of a certain size). Ruthenium oxide, glass frit to hold.

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 pre-processing and post-processing of these heating resistors.

This is because the particle size of ruthenium suroxide, etc. is
As stated in No. 4, it has a non-negligible size of 5 μm, and the determination of the resistance value of a thick film resistor is mainly based on M, -I at the contact interface with the μ-thenium oxide glass frit. , -Me (metaμm insulator meta/
This is because the cause is ultimately due to the heterogeneous bonding state of l/). Basically, the reason why the resistance value of thick film resistance materials changes significantly even though the firing temperature, atmosphere, and firing speed are the same can be presumed to be because the bonding state of M e I s-Me changes.

Therefore, thick film resistive materials such as ruthenium oxide and glass frit with 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 caused by non-uniformity of the contact interface is not improved, the variation in resistance value will not be improved. By the way, to improve variations in resistors (in this regard, lasers, trimming methods, etc. have traditionally been used to adjust resistance values, etc. mainly on thick film circuit boards, etc.)
This is implemented on thin film circuit boards, etc. Also, JP-A-58-
In the liquid jet recording head described in No. 7360 or Japanese Unexamined Patent Publication No. 58-7860, the thin film resistive element is laser trimmed,
The resistance value is adjusted to match the electrical-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 located above the heating resistor and pressing against 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 cut, and sand blasting 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]

This invention reduces the resistance value by applying voltage pulses across the heating resistor of the thermal head using a pulse generating circuit, thereby reducing variations in resistance. A resistance meter for measuring the resistance value of the heating resistor and a calculation section for calculating the average value or standard deviation of the resistance value are provided.

[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. This clouding can significantly reduce density unevenness in the print image quality of the thermal head.

[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 glass 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 method for reducing the resistance value of a heating resistor to eliminate 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-Metal)
Insulator of thick film resistor with structure
It is also thought that this is due to the breakthrough caused by voltage.

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

FIG. 1 shows a case where the resistance values of the heating resistors whose initial resistance values are R1, R2, and R8 are adjusted to Ro.

First, the resistance value of each heating resistor is measured and compared with the target resistance value R8. No voltage pulse is applied to a heating resistor having a resistance value lower than R6, such as R4. A voltage pulse is applied to the heating resistor having a resistance value R1°R2, R8 larger than Ro.

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 less than R0, a voltage pulse with a peak value of v0+ΔV is applied. After that, measure the resistance value, and if the value is less than R0, it is 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 less than R0. When the resistance value becomes less than R6, the adjustment is finished. In this way, the resistance value of the heating element is made to be within a certain range of R or less. Since the purpose of the present invention is to reduce the variation in resistance value, it is not sufficient that the resistance value be less than R, but it is required that it be within a certain range less than Ro. Therefore, the resistance value is gradually decreased and stopped when it becomes below R0.

@ Fig. 2 and Fig. 8 are diagrams showing the distribution of the resistance value of the heat generating resistor when the method of adjusting the resistance values using the manufacturing apparatus of the present invention is not carried out and when the method is carried out. Several heat generating resistors are shown as −g μm, 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 device of the present invention.

be. 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 (2) is the pulse generation circuit that generates the adjustment voltage pulse, αη is the resistance meter, (2) is the calculation unit, (to) is its input/output unit, α◆ is the central processing unit ( (2) is a memory, CIQ is a keyboard, and αη is a printer.

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

A setting signal for the peak value v8 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, measure the resistance value and set the target resistance value R.
For heating resistors with resistance values greater than 8, the following process is performed. Upon receiving the voltage application start signal 5TART from the calculation section (2), the pulse generation circuit turns into ENA.
Sends the BLE prohibition signal back to the calculation unit.
9) is switched to the pulse generation circuit QO side. ENABL
During the period when the E prohibition signal is output, changing of the peak value v6 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 5TART for applying the next voltage pulse should not be issued until the application of the current voltage pulse is finished. When a certain period of time T1 has elapsed after the application of the 5TART signal, the peak value of the pulse generating circuit QO becomes V.

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, switch (9)
) is switched to the resistance meter (6) side. And 18 more
After a period of time, the ENABLE prohibition signal is released and the next voltage application becomes possible, during which the resistance value is measured during 6 hours T8, and the measurement results are sent to the calculation section @. Calculation section (b)
Then, the CPU (141) compares the measured value with the previous measured value.Then, if the measured value is not within a certain range based on the previous measured value, it is determined that there is a contact failure.The method for setting the certain range is variable. However, the simplest method is to compare whether the value is higher than the previous measured value.The case of this method will be described below as an example.

If a higher accuracy than the previous measurement is obtained, then C
PUa barrels do not use this measurement, and instead use a blobbing device (
6), the probe is released from contact with the thermal head (7) to be measured, and a rib lobe 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, the re-contact is not made at the previous point, but at a slightly distant point.The probe is brought into contact at a suitable place called a pad provided at the end of the lead wire. Move it a little further away.

If the resistance side straightness is lower than the previous measured value, CPUQ4 adopts this measured value and compares it with the adjustment target value R0. If it has not reached Ro or below, after the ENABLE prohibition signal is released, the CPUQ41 increases the set value v8 of the peak value of the applied voltage pulse by ΔV and applies it to the beginning of the pulse generation port, and then controls the application of the next voltage pulse. Start signal for 5TAR
Generate T.

In this way, the resistance value of the heat generating resistor is gradually decreased while increasing the peak value of the applied voltage pulse. When the resistance value becomes less than the adjustment target value RO, the adjustment of the resistance value of the heat generating resistor is completed. do.

The switch (9) provides the time limit T, , T,
This is to avoid the influence of chattering in the switching connection circuit consisting of the relay network (8). Even if a voltage pulse is generated from the pulse generation circuit QQ before the switch (9) is completely switched to select the pulse generation circuit αQ side and the relay network (8) selects the − heating resistor, the pulse is not applied to the thermal head (7).

In addition, after applying the voltage pulse, the switch (9) is connected to the resistance meter (6).
Even if you measure the resistance value before the switch is completely switched to the ) side, accurate measurements cannot be made.

The reason why the time T2 is provided is that since it takes time for the voltage pulse to completely disappear Cζ, it is prohibited to switch the switch (9) during that time. 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 regulated by the peak value and the pulse width Δt, but if this becomes too large, the heating resistor will be destroyed. Rather than adjusting the pulse width of a single pulse, the width of each pulse in a group of pulses must be adjusted to reduce the pulse width depending on the peak value of the voltage pulse. While Δt is kept constant, it is easier to adjust the ratio Δ1/T between the pulse period T and the pulseless width Δt to a value that does not destroy the heating resistor according to the change in the peak value.Alternatively, Δt /T 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, it may be given as either a single pulse or a group of pulses. good.

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. Va in FIG. 1 indicates the peak value of the first applied voltage pulse.

The adjustment target resistance value R0 and the number of pulses n are changed using the keyboard αQ. Resistance value after adjustment and CPU (1
The calculation result of 41 is printed out on 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), the peak value v5. Initialize pulse conditions such as the number of pulses n. Next, in step (2), probing of the thermal head (7) by the probing device (6) and switching of the relay network (8) are performed.

Next, the resistance value is measured in step Z, and the measured value is compared with the target value R0 in step Y, and if it is smaller than Ro, no voltage pulse is applied. When the resistance value is greater than Ro, in steps (2) and (1), apply n pulse trains with the set peak value and measure the resistance value. A comparison is made in step (c), and if the measured value is greater than the previous measurement value, blobbing is performed again in step (7). If the measured value is smaller than the previous measured value, a comparison with the adjustment target resistance value RO is performed in step 2).If the measured value is less than or equal to R, the adjustment for that heating resistor is completed. If it is not below R, the peak value of the applied voltage pulse is increased by Δ■ and a pulse is applied (step @).

In principle, adjustment is continued in this manner until the measured value becomes R 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 M can generate. Therefore, even if the resistance value does not become below RO, the adjustment is terminated when the number of pulse voltage applications reaches a certain number. Steps are designed 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, the CPU α is the average value.

Calculation ΣR9ΣR2 is performed to obtain the standard deviation.

And the printer αη is the maximum value and average value of the group.

The minimum value is printed as shown in FIG. - After adjusting all the heating resistances of the thermal heads, the CPU α4
) calculates the overall mean and standard deviation σ. The results are output to a printer (b).

However, the calculation unit may calculate only one of the average value and standard deviation.

FIG. 7 is a detailed explanatory diagram of the pulse generating circuit αQ of FIG. 4. In the figure, (2), (7), and (2) are flip-flop circuits, on, (7), and (2) are timer circuits, and (2) are flip-flop circuits.
(to) is a pulse generator, (7) is a monostable multicircuit, (to) is a transistor, (b) is a voltage power supply, (to) is a counter, and (to) is a comparator.

Upon receiving the start signal 5TART signal from the calculation unit (2),
Flip-flop circuits (7) and (43) are set.

ENABL is sent from the flip-flop circuit (7) to the calculation section.
E prohibition signal is sent. While the ENABLE prohibition signal continues, changes in the peak value signal Vs and generation of the 5TART signal are prohibited. The coil/l/all of the switch (9) is energized by the output of the flip-flop circuit, and the contact -9- is switched to the side opposite to that shown in the figure. The timer circuit 0]) outputs T time after the flip-flop circuit (to) is set. As a result, when the flip-flop circuit (2) is set, the gate (to) is opened, and the pulses generated by the pulse generator (to) are transferred to the monostable multi-circuit (to).
7) is given. The monostable multi-circuit (to) shapes the pulse width of the pulse generator (to) into a pulse having a desired pulse width Δt. Δt is determined by the resistor and capacitor in the monostable multicircuit (7). FIG. 8 shows the output pulse waveform of the pulse generator (to) and the output waveform of the monostable Mars circuit.

The gate drive current of the transistor (to) is supplied by the pulse of the monostable multi-circuit (7), and the transistor (to) is in an ON state for a period Δt during which the pulse exists.

Voltage power supply (2) during the period when the transistor (to) is in the ON state
The output voltage of the switch (9) contacts -, opposite, and relay network (
8) to the sample. The peak value of the voltage power source (b) is determined by the peak value signal V3 from the calculation unit @.

The pulses passing through the gate (b) are counted by a counter. The count value of the counter (to) is compared with the number n given from the calculation unit @ by the comparator (to).

When the count value reaches n, the output of the comparator (to) is reset (to the flip-flop circuit). As a result, the gate (b) is closed, and one pulse voltage application to the sump ends.

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

After the time limit T2, the timer circuit (g) outputs an output, which resets the flip-flop and switches the switch (9) to resistance measurement. When the switch (9) is switched, the contacts and needles are switched to the illustrated positions, and the resistance value of the heating resistor of the sample is measured by the resistance meter αη.

When 13 hours have elapsed since the timer circuit (7) outputs the output, the timer circuit (6) outputs the output, thereby resetting the flip-flop circuit (the flip-flop circuit), the outputs from both terminals become 1H level, and the ENABLE inhibit signal disappears. This makes it possible to apply 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 implemented, the absolute value within a thermal head having 2000 or more heating resistors per piece is ±20%,
While the standard deviation σ was 5.6%, when the present invention was implemented, the variation in resistance values was significantly improved, with an absolute value of ±3% and a standard deviation of 0.4%. This made it possible to almost eliminate density unevenness in printing by the thermal head.

The inventors set the initial setting value (Vo in Fig. 1) of the peak value of the voltage pulse applied to adjust the resistance value to several tens of v1, and the increment △V for each pulse voltage applied was set to 1 v to several tens of v1. V, the number of puffs included in one voltage application n is 10 to 20.1, the pulse width Δt is 1 μ to several μ seconds, and the pass μ interval is several tens of μ seconds to adjust the resistance value of the heating element. Ta.

Time limit T1. The inventors adjusted the resistance value by setting T8 to around 10 msec and 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, a comparison is made with the previous resistance measurement value, which 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 V of the pulse voltage and the number n of pulses are automatically given to the pulse generation circuit QO from the calculation section 2, they can also be written to be set manually. it is,
This can be easily implemented by providing the pulse generation circuit with a switch for setting the peak value (3) and the number of pulses (n). Further, both automatic setting from the calculation section (6) and manual operation may be used together.

In the example of Fig. 7, the switch (9) is a relay that connects Koi/L/# old ζ and drives contacts □□□, (!11).
It is also possible to use a semiconductor switch instead.

〔Effect of the invention〕

This invention (this thermal head manufacturing apparatus includes a pulse generation circuit that applies a voltage pulse to a heating resistor to reduce its resistance value, and a resistance meter that measures the resistance value of the heating resistor) By reducing the variation in the resistance value of the heating resistor of the thermal head, it is possible to significantly reduce the unevenness of the print density of the thermal head.Also, a calculation section is provided to calculate the average value or standard deviation of the resistance value. This makes it easier to understand how much the variation in data has been reduced.

[Brief explanation of drawings]

Figure i1 is an explanatory diagram of the principle of the method for manufacturing a thermal head according to the present invention, and Figures 2 and 3 are diagrams showing cases in which the manufacturing process for equalizing resistance values by the thermal head manufacturing apparatus according to the present invention is not carried out and when it is carried out. 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. A flowchart showing one implementation procedure of the manufacturing process by the thermal head manufacturing apparatus according to the invention, FIG. 7 is a detailed configuration diagram of the pulse generation circuit of FIG. 4, FIG. 8 is a waveform explanatory diagram of FIG. 7, and FIG. Figure 5110 is a diagram illustrating the general configuration of a thermal head, Figure 5110 is a diagram illustrating how the thermal head is used in a thermal recording device, and Figure 11 is a diagram showing an example of the distribution of resistance values in a general thermal head. 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, αQ is the pulse generation circuit, (b) is the resistance meter, (b)
is the calculation unit, (b) j, tcPU, C3]), ■, ni) is the timer circuit, 轡 is the pulse generator, (to) is the monostable multi-circuit, (b) is the voltage power supply, (to) is the counter Container, (to) is a comparator. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] a pulse generating circuit that applies a voltage pulse to a predetermined heating resistor selected from a plurality of heating resistors of the thermal head; a resistance meter that measures the resistance value of the heating resistor;
A thermal head manufacturing apparatus comprising: a calculation section that calculates an average value or a standard deviation value of the resistance value of the heating resistor based on the plurality of measured values of the resistance meter.