JPS61251106A - Apparatus for manufacturing thermal head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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]

Currently, thermal heads that do not require fusing, are noiseless, maintenance free, and have high reliability 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 in contact with the resistor. Melts the ink layer on the paper,
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 AI, Au, and Ou on an insulating substrate (1).
A heat generating element is constituted by a lead part (2) made of a good electrically conductive material such as by film-forming technology and a film-like element resistor (3) connected to both ends thereof.

As the material of the insulating substrate (1), an alumina ceramic substrate or an alumina ceramic substrate with a haglaze layer is often used. In the case of a thin film type, the material for the element resistor (3) is Ta2N, Ta-8in2. Ta-81,N
A material such as i-0uT1□03 is used.

Further, in the case of a thick film method, a noble metal oxide such as RuzOePtO 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, Joule heat (Kl) heat is generated in the resistor section. This heat is transferred to A of the recording device configured as shown in Figure 11.
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. 11, the first
The same symbols as in Figure 0 indicate corresponding parts. P indicates the suppression direction of roll (4).

In general, thermal heads for facsimile machines, for example, have approximately 2,000 resistors arranged independently and in parallel as heating resistors per head. Temperature is 250℃~600℃
The thermal head is heated to about 0.degree. C., and the applied energy equivalent to reaching this temperature is required to be approximately 0.2 mJ (joule) to 2 mJ, depending on the degree of decomposition of each thermal head.

Traditionally, thermal heads have been divided into thick-film types, thin-film types, and semiconductor types, 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, 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 be used as a resistor, and then photo-etched to form 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 three 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. Since thermosensitive recording is determined by the resistance value of a resistor and utilizes the generated Joule heat, variations in resistance value naturally cause density unevenness in the quality of the image printed thereon.

FIG. 12 shows an example of resistance values R1, R2, Rfi of each element resistor constituting the thermal head.

Normally, the resistance value variation of thin film type is uniform within ±5- to ±15%, while for thick-film type, it is uniform within ±15- to ±3.
Although it is inferior to the thin film type, it has the major advantages of high reliability such as overload power and wear resistance, and low cost. Therefore, even with the thick film type, it has recently become possible to form fine patterns as fine as with the thin film type. For example, in forming a conductor pattern, a printed film thickness of 3 μm or more was conventionally required, but a conductor film thickness of 3000 Å or less can also be formed. This advantage is that the etching factor during photoetching, which conventionally required 20 μm, is about the same as that of the thin film type, that is, t! On the other hand, in order to improve the variation in resistance value of thick film type, in addition to improving conventional screen printing technology such as improving mesh screens and metal mask screens, for example, Photo-etching of thick film resistors as described in No. 59-22675, and
- Method of embedding a thick film resistor in a photoresist turn as described in No. 18506, JP-A-54-9944.
There is a method of polishing the surface of a thick film resistor as described in No. 3. Furthermore, as described in 1975-4'759'FK, there are products in which a thick film resistor is printed on a thin film conductor. It was an attempt to improve.

Improvements in thick film resistor materials have also been made.

As a thick film resistance material, for example, Japanese Patent Application Laid-Open No. 53-954
Ruthenium oxide, high melting point frit glass, zirconium oxide, etc. described in No. 4 and JP-A-53-9543 are suitable; however, these are mainly improved to maintain reliability as a thick film type thermal head. However, the variation in heating resistance values has not been improved.

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 actually be the same as that of a thin film resistor. The resistance value is expressed by the following formula.

Here, ρ: Specific resistance of the resistor (Ω-am) l: Length of the resistor (am) W: Width of the resistor (am) t: Thickness of the resistor (cm) Screen-printed heating resistor Normally, the length of the resistor (l), the width of the resistor (W), and the thickness of the resistor (1) vary slightly, but ultimately the problem is basically the thick film resistor material. This is the variation in the specific resistance of the resistor itself caused by the difference in the degree of bonding that occurs during firing of ruthenium oxide, glass frit, zirconium oxide, etc. that maintain the same particle size, and the resulting variation in resistance value. This is a thick film manufacturing process with strict screen printing,
The problem cannot be solved even by improving the firing conditions and the pre-processing process for manufacturing these heating resistors. this is,
As stated in JP-A-53-9544, the particle size of ruthenium oxide, etc. is 5 μm, which cannot be ignored, and ruthenium oxide glass frit is mainly used to determine the resistance value of thick film resistors. M of the contact interface with -
This is because the cause is ultimately due to the inhomogeneous bonding state of I, -Me (metal-insulator metal). 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 M6-I and -M 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 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, adjustment of resistance values has conventionally been carried out mainly on thick film circuit boards, thin film circuit boards, etc. by using a laser trimming method or the like. Also, JP-A-58-736
In the liquid jet recording head described in No. 0 or JP-A-38-'7360, the thin film resistance element is laser trimmed to adjust the resistance value to match the electric-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, so mechanical trimming methods such as laser, diamond cutting, and sandblasting deteriorate the performance of the thermal head due to changes in shape. could not be used due to

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 a voltage pulse having a specified rise time and a specified fall time to the heating resistor of the thermal head using a pulse generation circuit, thereby eliminating variations in resistance. decrease.

[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 glass film on a substrate, a process of reducing the resistance value is carried out using the apparatus of the present invention.

Figure g1 is a diagram showing the principle of a production method that reduces the resistance value of the 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 MI
It is also believed that this is because the insulator of the thick film resistor having a (Metal-Insulator-Metal) structure undergoes voltage breakthrough.

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

Figure 1 shows the case where the resistance values of heating resistors whose initial resistance values are R, R2, and R3 are adjusted to R8.0 First, the resistance value of each heating resistor is measured and the Compare it with the resistance value R8. No voltage pulse is applied to a heating resistor, such as R4, which has a lower resistance value than R6. A voltage pulse is applied to the heating resistor having resistance values R1, R2°R3 that are larger than Ro.0 First, the initial setting of the peak 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 R8 or more, it is V. A voltage pulse with a peak value of +ΔV is applied. After that, measure the resistance value, and if the value is R8 or more, 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 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 this invention is to reduce the variation in resistance value, it is not enough that the resistance value is less than Ro, but within a certain range less than RO&C.
6 things are required. 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 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. Several heating resistors are grouped into a - group, and the maximum value is shown with a white circle, the average value with a thick black mark, and the minimum value with an X mark.

★If it is not applied, 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. Figure 5 is a waveform diagram of the main signals in Figure 4.0 (6) is the thermal head to be adjusted (7) A probing device that presses the IC probe (globe), (8) is the desired applied voltage pulse. relay network leading to the heating resistor, (9)
is a switch that switches between voltage application and resistance measurement, α is a pulse generation circuit that generates an adjusted voltage pulse, (b) is an ohmmeter, (6) is a calculation section, (to) is its input/output section, ( B)
is a central processing unit (hereinafter referred to as CPU), 01 is a memory, 01 is a keyboard, and α is a 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, measure the resistance value and set the target resistance value R.
For heating resistors with resistance values greater than 6, the following process is performed. Upon receiving the voltage application start signal 5TART from the calculation section (2), the pulse generation circuit a [is EN
The ABLE prohibition signal is sent back to the calculation section. Also, switch (
9) is switched to the pulse generating circuit α1 side. ENAB
During the period when the LE prohibition signal is output, changing of the peak value v8 and generation of the 5TART signal are prohibited. This is because the peak value Ve should not be changed while the voltage pulse is being applied, and the start signal 5TAR'l' for applying the next voltage pulse should not be issued until the application of the current voltage pulse is finished. It is. 5 When a certain period of time T1 has elapsed after the application of the TART signal, the pulse generation circuit (11 indicates that the peak value is v).
n pulses of e are applied to the heating resistor of the thermal head (7) via the switch (9) and the relay network (8). The switch (
9) is switched to the resistance meter α force side. And Sara KT3
After a certain period of time, the ENABLE inhibit 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 (6), the CPU (b) 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 many ways to set a certain range, but the simplest method is to compare whether the value is much higher than the previous measured value. Below 0 - For example, in this method 0 If a higher value than the previous measurement value was obtained, 0
The PUQ 41 does not use this measurement value, but sends a reprobe signal to the probing device (6) K to release the probe from the thermal head (7) to be measured and 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 R6.

cpUQ4 is ENABLE if it has not reached Ro or below.
After the prohibition signal is released, the set value v8 of the peak value of the voltage pulse to be applied is increased by △■ and given to the pulse generation circuit α value, and then the start signal 5 for applying the next voltage pulse is generated.
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. When the resistance value becomes equal to or less than the adjustment target value R8, the adjustment of the resistance value of the heating resistor is completed.

The time limits T, , T3 are provided in order to avoid the influence of chattering in the switching connection circuit consisting of the switch (9) and the relay network (8). The switch (9) is switched to the pulse generating circuit member side, and the relay network (8) selects the - heating resistor, so that one pulse generating circuit O is switched completely before the switch (9) is switched to the pulse generating circuit side.
Even if a voltage pulse is generated from I, the pulse is not applied to the thermal head (7).

Further, even if the resistance value is measured before the switch (9) is completely switched to the resistance meter (b) side after the voltage pulse is applied, accurate measurement cannot be made.

The reason why the time limit T2 is provided is that since it takes time for the voltage pulse to completely disappear, switching of the switch (9) is prohibited 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 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 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 pulse in a pulse group consisting of multiple pulses is kept constant, and the ratio Δt/T of the pulse period T to the pulse width Δt is set to the peak value. It is easier to adjust the heating resistor to a value below which will not destroy the heating resistor according to the change. Alternatively, Δt/'I' 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 zero voltage pulse is sufficiently small, it is possible to You can give it at any time.

Rise time 1r and fall time tf of voltage pulse
must be as steep as possible. If tr + T'f is long, the waveform of the applied pulse will be distorted, making it impossible to apply the intended energy. This is because, especially when tl becomes long and the peak value is high, extra energy is applied, leading to damage to the heating element.

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. V in Figure 1. represents the peak value of such a first applied voltage pulse.

The adjustment target resistance value R8 and the number of pulses n are changed using the keyboard aQ. The adjusted resistance value and the calculation result of the CPU (b) are 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 (A), initial settings of pulse conditions such as the wave height value VB and Hals number n are performed.Next, in step Qη, the blowing device (6) blows the thermal head (7), and the relay network (8) and switching.

Next, measure the resistance value using a stepper. Step (51
), the measured value is compared with the target value R6, and if it is smaller than R6, no voltage pulse is applied. When the resistance value is greater than Ro, a train of n pulses having a set peak value is applied to the step wire and wire, and the resistance value is measured. The current measurement value is compared with the previous measurement value in step (good), and if it is larger than the previous measurement value, probing is performed again in step (a). If it is smaller than the previous measurement value, adjust target resistance value R
Comparison with o is performed in step (e). If the measured value is R8 or less, the adjustment for that heating resistor is completed. R
If it is not below o, 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. In addition, there is a limit to the peak value of the pulse voltage that can be generated by the pulse generation circuit (1), so even if the resistance value does not become less than Ro, when the number of pulse voltage applications reaches a certain number, Finish the adjustment.

Steps are provided for this purpose.

It was already mentioned in Figures 2 and 3 that the resistance value is measured using several heating resistors as a group.When the adjustment for one group is completed, 0PUQ4 is the calculation to calculate the average value and standard deviation. Perform ΣR9ΣR2. And the printer aη is - the maximum value, average value, and minimum value of the group are the third
Printed as shown. - When the adjustment of the total heat generation □ resistance of the thermal heads is completed, the CPU α→ calculates the overall average value and standard deviation σ. The result is output to the printer αη.

FIG. 7 is a detailed explanatory diagram of the pulse generating circuit α shown in FIG. In the figure, CIJ, @, (Incorporated) is a flip-flop circuit, 01), @*, (6) is a timer circuit, (
(to) is a pulse generator, (to) is a monostable multicircuit, (to) is a transistor amplifier circuit, (to) 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),
717 flop flop circuit (to), @3 is set.

From the flip-flop circuit (7) to the calculation section] 1nNA
A BIJ prohibition signal is sent. While the ENABLE prohibition signal continues, the peak value signal VB is changed and S'rAR'
Generation of the I' signal is prohibited. Flip-flop circuit (
The coil (91) of the switch (9) is energized by the output of the switch (9), and the contact (92) is turned on.

(93) is switched to the opposite side as shown. The timer circuit (b) outputs an output T1 time after the flip-flop circuit (to) is set. When the flip-flop circuit (to) is set from this K, the gate (2) is opened and the pulse generated by the monostable multi-circuit c!
aK is given. The monostable multicircuit (2) shapes the pulse width of the pulse generator into a pulse having a desired pulse width Δt. Δt is determined by the resistor and capacitor in the monostable multicircuit (2).
) and the output waveform of the monostable multicircuit (7) are shown.

The gate drive current of the transistor amplifier circuit (to) is supplied by the pulse of the monostable multi-circuit, and the transistor amplifier circuit (to) is ON during the period when the pulse exists.
state. While the transistor amplifier circuit (to) is in the ON state, the output voltage of the voltage power source (b) is applied to the sample via the contacts (92) and (93) of the switch (9) and the relay network (8). The peak value of the voltage source) is determined by the peak value signal 8 from the calculation unit @.

Pulses passing through gate ■ are counted by counter @. The count value of the counter (to) is compared with the number n given from the calculation unit (to) 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 is also given to the timer circuit.

After the time limit T2, the timer circuit (A) outputs an output, which resets the flip-flop, and the switch (9)
) is switched to resistance measurement. When the switch (9) is switched, the contacts (92) and (93) are switched to the positions shown in the figure, and the resistance value of the sample heating resistor is measured by the resistance meter (B). The timer circuit (G) is activated. When time T3 has elapsed since the output, the timer circuit (6) outputs an output, which resets the flip-flop circuit, and the output from the opposite terminal goes to the "H" level, and the ENABIE prohibition signal disappears.This causes the next υ Application of voltage pulses becomes possible.

FIG. 9 is a detailed explanatory diagram of the transistor amplifier circuit. The pulse output of the one-shot multi-circuit (to) drives the gate circuit of the transistor (362) via a buffer (361) and a protection resistor (367). As a result of this, the transistor (362) is turned on and its collector voltage becomes 'L' level.
3), the base current flows through the transistor (364) and turns it on, and the collector voltage goes to the "H" level, so the transistor (364) is turned on.
Do N. Then, the voltage at the terminal (3'70) of the voltage power source (b) is applied to the output terminal. The output terminal is a switch (9
) is connected to the sample. (365).

(366) are transistors (363) and (364) respectively
By using this transistor amplifier circuit, a trimming pulse with a predetermined peak value and a steep rise and fall can be obtained.

It is better for the rise and fall of the pulse to be as short as possible,
Limited by circuit conditions. The inventors have confirmed that the heating resistor will not be destroyed by the applied pulse if the rise time is within 1oon θ and the fall time is 2000 ns or less.

As long as a transistor amplifier circuit is configured, the fall time must be longer than the short rise time.

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% and the standard deviation σ is 5.6-, whereas when the present invention is implemented, the absolute value is ±3% and the standard deviation is 0. ．．
The resistance variation was significantly improved to 4%. By doing this, it was possible to almost eliminate density unevenness in the print of the thermal head. The initial setting value of the peak value of the voltage pulse applied for 4F5 (Fig. 1 V.) is several tens of v1, and the increment ΔV for each pulse applied is 1v, and then several V is obtained.
The number of pulses n included in one voltage application is 10 to 20.1.
The pulse width Δt is 1 μ to several μ seconds, the pulse rise time is 1oon88G or less, and the fall time is 500 nse.
c, the resistance value of the heating element was adjusted by setting the pulse interval to several tens of microseconds.

Time limit T1. The inventors adjusted the resistance value by setting T3 to around low seconds and setting time T2 to several milliseconds.

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 can be used within the range that produces the effects of the present invention.

In the step 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 the resistance value is within the double range, and re-measure the resistance value if it is not within this range.
Although shown in FIG. 7, the present invention is not limited thereto.

Although the peak value ve of the pulse voltage and the number of pulses n are automatically given to the pulse generation circuit a from the calculating section (2), they 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 shown in Figure (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 semiconductor switch instead. .

〔Effect of the invention〕

The thermal head manufacturing apparatus according to the present invention includes:
By applying a voltage pulse with a steep fall time to the heating resistor to reduce the resistance value, the variation in the resistance value of the heating resistor of the thermal head is reduced, and the unevenness of print density of the thermal head is significantly reduced. Not only can this be reduced, but also the destruction of the heating resistor due to the application of voltage pulses can be prevented.

[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 FIGS. 2 and 3 are diagrams showing a case in which the manufacturing process for making the resistance values uniform by the thermal head manufacturing apparatus according to the present invention is not 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. 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 pulse generation circuit of FIG. 4, and FIG. 8 is an explanation of the waveforms of FIG. 7. Fig. 9 is a circuit diagram of the pulse amplification circuit;
Figure 0 is a general configuration diagram of a thermal head, Figure 11 is a diagram illustrating how the thermal head is used in a thermal recording device, and Figure 12 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 probing device, and (7) is a probing device.
) is the thermal head, (8) IJ L/-net, (9)
Ha switch, C1 (It is the pulse generation circuit, αη is the resistance meter, 02 is the calculation section, α→ is 0PUS 01), @*
, (9) is a timer circuit, (to) is a pulse generator, (to) is a monostable multi-circuit, (to) is a transistor amplifier circuit, (b) is a voltage power supply, (to) is a counter, (to) is a comparator. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A pulse generation circuit that applies a steep voltage pulse with a rise time within a predetermined value and a fall time within a predetermined value to the heating element of the thermal head, and a resistance meter that measures the resistance value of the heating resistor. Thermal head manufacturing equipment equipped with (2) The thermal head manufacturing apparatus according to claim 1, wherein the voltage pulse has a rise time of 100 ns or less and a voltage pulse fall time of 2000 ns or less.