JP2003226020A - Adjusting method of resistance value of thermal inkjet head - Google Patents

Abstract

(57) [Problem] To provide a resistance value adjusting method capable of forming a clear image on recording paper and obtaining a thermal ink jet head capable of coping with high-speed recording. A predetermined gap is provided between a plurality of heating elements made of a resistive thin film and a power supply wiring electrically connected to the heating elements on a top surface of a base plate. A thermal ink jet head comprising a top plate disposed as described above and filling the gap with ink, wherein the electric resistance value of the heating elements is determined by applying a predetermined power pulse to each heating element. Ink is ejected from the ejection holes and the speed is measured. Step 1 is compared with the ejection speed obtained in Step 1 and the reference speed, and the speed difference between the two is determined.
Step 2 of selecting a trimming pulse corresponding to the speed difference
And 3) adjusting the electric resistance of the heating element by applying the trimming pulse selected in step 2 to the corresponding heating element.
And adjust through.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance value adjusting method for a thermal ink jet head, in which ink droplets are adhered in a predetermined pattern on a recording paper to record an image.

[0002]

2. Description of the Related Art Conventionally, an ink jet head has been used as a recording device for forming an image on recording paper.

The ink jet head recording system uses a thermal energy generated by a heating element to eject ink droplets toward a recording sheet, a deformation of a piezoelectric element, and an electromagnetic wave irradiation. The thermal inkjet type that uses the heat energy of the heating element is easy to pattern the heating element, and even if the heating element has a small area. Since it can generate a relatively large amount of heat energy, it is attracting attention as being suitable for high-density recording.

As such a thermal ink jet head, for example, as shown in FIG. 7, a plurality of heating elements 23 linearly arranged on the upper surface of a base plate 22 made of single crystal silicon or the like and the heating elements 23 are electrically connected to each other. A top plate 25 having a plurality of ink discharge holes 26 corresponding to the heating elements 23 in a one-to-one correspondence is formed on a head substrate 21 to which a power supply wiring 24 to be connected is attached, with a predetermined gap therebetween. The head substrate 21-
It is known that the gap between the top plates 25 is filled with the ink 27, and while the recording paper is conveyed along the outer surface of the top plate 25, the plurality of heating elements 23 are converted into image data from the outside. Based on this, Joule heat is selectively generated individually to generate bubbles A in the ink 27 on the heating elements 23, and the heating elements 23 are generated by the pressure of the generated bubbles A.
A predetermined image is recorded by pushing up the upper ink 27 to the ink ejection hole 26 side and ejecting a part of the ink 27 toward the recording paper from the ink ejection hole 26.

The heating element 23 and the power supply wiring 24 provided on the head substrate 21 are usually patterned by a well-known thin film forming technique. Specifically, first, a resistance thin film made of TaSiO or the like and a metal thin film made of aluminum or the like are sequentially deposited on the upper surface of the base plate 22 by sputtering or the like, and these are finely processed by photolithography, etching technique, or the like to generate a heating element. 23 and the power supply wiring 24 were patterned.

[0006]

However, in the above-described conventional thermal ink jet head, when the heating element 23 is formed by the conventionally known thin film forming technique, the shape and thickness of the heating element 23 may cause variations in manufacturing conditions. This often results in non-uniformity. Therefore, it is difficult to make all the electric resistance values of the heating elements 23 equal.
When a recording operation is performed using a thermal ink jet head having such resistance variation, the thermal energy generated by the heating elements 23 and the ink ejection speed differ from one heating element to another, causing image distortion. Had.

Therefore, in order to solve the above-mentioned drawbacks, the electric resistance value of the heating element 23 is individually measured, and the correction data is created based on the measured resistance value. It has been proposed that the heat energy generated by the heating element 23 be made uniform by adjusting the power applied to the heating element 23.

However, when adjusting the electric power applied to each heating element 23 using the correction data, a large memory for storing the correction data to be applied to all the heating elements 23, a complicated correction circuit, a power supply circuit, etc. Is required separately, and the configuration of the thermal inkjet head and the printer body in which it is incorporated is significantly complicated, and since such correction is performed for each printing line, the time required for recording operation is prolonged. As a result, a defect that causes a decrease in recording speed is induced.

The present invention has been devised in view of the above-mentioned drawbacks, and an object thereof is to form a clear image with little distortion on a recording paper, and to maintain a simple structure to increase the recording speed. Another object of the present invention is to provide a method for adjusting the resistance value of a thermal inkjet head that can provide a high-performance thermal inkjet head that is also compatible with the above.

[0010]

According to a method of adjusting a resistance value of a thermal ink jet head of the present invention, a plurality of heating elements made of a resistive thin film are provided on an upper surface of a base plate, and a power supply wiring electrically connected to the heating elements. A head plate is formed on a head substrate formed by adhering and, and a top plate is disposed so as to form a predetermined gap therebetween, and ink filled in the gap is ejected by thermal energy generated by the heating element. A thermal ink jet head for forming an image by ejecting from a hole, wherein the electric resistance value of the heating element causes a predetermined power pulse to be applied to each heating element to eject ink from the ink ejection hole, Step 1 for measuring the ink ejection speed, the ink ejection speed measured in Step 1 is compared with a predetermined reference speed to obtain a speed difference between the two,
Step 2 of selecting a trimming pulse corresponding to the speed difference, Step 3 of applying the trimming pulse selected in Step 2 to the corresponding heating element to adjust the electric resistance value of the heating element
It is characterized by being adjusted through.

In the method of adjusting the resistance value of the thermal ink jet head of the present invention, the heating element is covered with a protective film made of an inorganic material containing silicon and oxygen.
A part of the heating element to which the trimming pulse is applied reacts with oxygen in the protective film to form an oxide film on the surface of the heating element, and the resistance value of the heating element is increased to adjust the resistance value. It is characterized by having done.

Further, the resistance value adjusting method of the thermal ink jet head of the present invention is characterized in that the oxygen content in the protective film is set to 2.0% by mass to 10.0% by mass. is there.

Furthermore, in the resistance value adjusting method of the thermal ink jet head of the present invention, in the middle of the power supply wiring,
In addition, the trimming pulse is applied to the corresponding heating element through the pad for trimming provided outside the ink filling area.

According to the adjusting method of the present invention, the variation in the resistance value generated in the heating element when the heating element is formed by the thin film forming technique can be accurately corrected by pulse trimming. It is possible to obtain a high-performance thermal inkjet head capable of forming a clear image with less distortion, by making energy and ink ejection speed substantially equal.

Further, according to the adjusting method of the present invention, the electric energy of the heating element is adjusted by adjusting the electric resistance value of the heating element, so that the applied power is adjusted using the correction data. In comparison with the case, a memory for storing correction data, a complicated correction circuit, a power supply circuit, etc. are not required, and the structure of the thermal inkjet head and the printer body in which it is installed can be simply maintained, and at the same time, during the recording operation. Since no correction processing is required at all, it is possible to obtain a high-performance thermal inkjet head that can easily cope with an increase in recording speed.

Further, according to the adjusting method of the present invention, since the heating element to which the trimming pulse is applied is covered with the protective film made of the inorganic material containing silicon and oxygen,
By reacting part of the heating element with oxygen in the protective film to form a thin oxide film on the surface of the heating element, it becomes possible to increase the resistance value of the heating element. It is possible to correct both up and down.
Therefore, when adjusting the resistance value, the target resistance value can be set so that the maximum value of the energy of the trimming pulse applied to the heating element becomes small, and the heating element becomes excessively hot when the trimming pulse is applied. It is possible to effectively prevent the heat loss of the heating element due to the above.

Further, according to the adjusting method of the present invention, the resistance when a predetermined trimming pulse is applied is set by setting the oxygen content in the protective film to 2.0% by mass to 10.0% by mass. There is also an advantage that the degree of increase in the value becomes an appropriate size, and finer resistance value adjustment becomes possible.

Furthermore, according to the adjusting method of the present invention, by applying the trimming pulse to the heating element via the trimming pad provided in the middle of the power supply wiring and outside the ink filling area, Even after assembling the thermal inkjet head, the probe (probe) of the probing device used for applying the trimming pulse can be surely and easily brought into contact with the pad for trimming. There is also an advantage that the workability of trimming becomes good.

[0019]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below in detail with reference to the accompanying drawings. 1 is an exploded perspective view of a thermal inkjet head obtained by an adjusting method according to an embodiment of the present invention, and FIG. 2 is a sectional view of the inkjet head of FIG. 1, in which 1 is a head substrate and 7 is a ceiling. A plate and 9 are inks.

The head substrate 1 has a plurality of heating elements 3 linearly arranged on an upper surface of a base plate 2 formed in a rectangular shape, and a power supply wiring electrically connected to the heating elements 3. 4 and 4 are deposited and formed, and these are formed into a protective film 6
It has a structure covered with.

The base plate 2 is made of a semiconductor material such as single crystal silicon or an electrically insulating material such as glaze alumina ceramics, and supports the heating element 3, the power supply wiring 4, the protective film 6 and the like on its upper surface. It functions as a supporting base material.

When the base plate 2 is made of, for example, single crystal silicon, a well-known Czochralski method (pulling method) or the like is used to form an ingot (lump) of single crystal silicon, and the ingot is formed to a predetermined thickness. It is manufactured by slicing into pieces and processing the outline. In this case, an insulating film (not shown) made of an electrically insulating material such as silicon oxide (SiO ₂ ) is provided on the surface of the base plate 2 to have a thickness of, for example, 1 μm to 3 μm. The single crystal silicon forming 2 is electrically insulated from the heating element 3 and the like.

The plurality of heating elements 3 provided on the upper surface of the base plate 2 are, for example, 600 dpi.
They are arranged linearly in the main scanning direction at a density of (dot per inch), each of which is TaN, TaSiO, or TaSiN.
It is formed of a resistance thin film made of an electric resistance material such as O, TiSiO, TiSiCO, NbSiO.

Since the heating element 3 itself is made of an electric resistance material, when power source power is supplied through the power supply wiring 4 and the like, Joule heat is generated and bubbles A are generated in the ink 9. Generates the required thermal energy required for

The heating elements 3 are subjected to resistance value correction by pulse trimming, which will be described later,
All the heating elements 3 are adjusted so as to generate substantially uniform heat energy during the recording operation.

Further, the power supply wiring 4 connected to the heat generating element 3 is for applying power source power to the heat generating element 3 described above, and one end of the power supply wiring 4 is led out to the outside of the ink 9 filling area described later. The lead-out portion is connected to a terminal such as a driver IC (not shown).

In addition, each of the power supply wirings 4 has a trimming pad 5 having a circular shape or a square shape larger than the line width of the wiring 4 outside the filling area of the ink 9 in the middle of each of these pads. 5 are arranged in a line in a direction (main scanning direction) parallel to the arrangement direction of the heating elements 3.

The pad 5 is for contacting a probe of a probing device for applying a trimming pulse when adjusting the electric resistance value of the heating element 3 by a conventionally well-known pulse trimming method. It is positioned outside the edge of the top plate 7 so that the trimming work can be easily performed even after the inkjet head is assembled.

The heating element 3 and the power supply wiring 4 are formed by a conventionally known thin film forming technique such as sputtering, photolithography, etching technique, or the like. Specifically, first, a resistive material such as TaSiO and a metallic material such as aluminum are sequentially deposited on the upper surface of the base plate 2 by the conventionally well-known sputtering to form a laminated body composed of a resistive thin film and a metallic thin film. The heating element 23 and the power supply wiring 4 are formed by fine processing using well-known photolithography and etching techniques.
Are patterned into a predetermined shape, and after the assembly process of the thermal inkjet head is completed, each heating element 3
The electric resistance value of is adjusted by the adjusting method described later.

The pad 5 of the power supply wiring 4 is applied to a predetermined portion of the power supply wiring 4 by nickel plating, gold plating or the like by a well-known electroless plating method or the like to have a thickness of, for example, 2 μm to 5 μm. It is formed.

The protective film 6 covering the heating element 3 and the power supply wiring 4 is corroded by the alkali ions and water contained in the ink 9 coming into contact with the heating element 3 and the power supply wiring 4. Alternatively, it is for effectively preventing the solidification of the dye contained in the ink 9 from adhering to the surface of the heating element 3, and an inorganic material containing silicon and oxygen, such as SiO ₂ (oxidation). Silicon) or SiON is formed to have a thickness of, for example, 0.2 μm to 2.0 μm.

The oxygen in the protective film 6 is combined with the resistance material forming the heating element 3 when the resistance value of the heating element 3 is increased by pulse trimming, and a thin oxide film is formed on the surface of the heating element 3. It has a function of forming, and its content is set to 2.0% by mass to 10.0% by mass.

Further, the protective film 6 has its end located closer to the heating element 3 side than the pad 5 so that the pad 5 is exposed, and the conventionally known sputtering, vacuum deposition method, plasma CVD ( Chemical Vapor Deposition)
Etc., and the above-mentioned inorganic material is applied to the surface of the heating element 3, the power supply wiring 4, etc. to a predetermined thickness.

On the other hand, on the above-mentioned head substrate 1,
The top plate 7 is arranged so as to form a predetermined gap therebetween.

The top plate 7 is for closing the ink flow path made of the ink 9 filled in the gap with the head substrate 1, and has a plurality of ink ejection holes corresponding to the heating elements 3 in a one-to-one correspondence. 8 so that the outer dimension thereof is smaller than that of the head substrate 1 in the sub-scanning direction. Specifically, one end of the top plate 7 is located closer to the heating element 3 than the pad 5 is. It is located in.

The top plate 7 is positioned so that the ink ejection holes 8 are located right above the corresponding heating elements 3, and ink drops i are ejected from the ink ejection holes 8 through the ink ejection holes 8 during recording operation of the ink jet head. It is designed to discharge toward.

The top plate 7 is a plate made of metal such as molybdenum, a plate made of ceramics such as alumina ceramics, a plate made of resin such as epoxy resin or polyimide resin, or the above-mentioned materials. In the case of molybdenum, for example, a molybdenum ingot (lump) is formed into a plate shape by a conventionally known metal working method, and a conventionally known etching technique or the like is adopted at a predetermined portion of the plate body. Drilling with a diameter of 10
A top plate 7 manufactured by forming a large number of ink ejection holes 8 of about 100 μm to 100 μm is placed and adhered on the head substrate 1 via a spacer, a sealing member 11 or the like (not shown). Thus, the top plate 7 is fixed at a predetermined position on the head substrate 1.

As the ink 9 filled in the gap between the head substrate 1 and the top plate 7, for example, an aqueous dye ink is preferably used, and the viscosity thereof is, for example, 0.3 mPas.
-Adjusted to s-3.0 mPa-s (25 ° C).

The ink 9 as described above is supplied from an ink tank (not shown) to the gap between the head substrate 1 and the top plate 7, and bubbles are generated in the ink 9 by the thermal energy from the heating element 3 described above. When A occurs, a part of the ink 9 is partially ejected by the ink ejection holes 8 due to the pressure when the bubbles are generated.
As a result, ink droplets i are ejected to the outside, and a predetermined image is formed by attaching these ink droplets i to the surface of the recording paper conveyed along the outer surface of the top plate 7.

Next, a method of adjusting the resistance value of the thermal ink jet head described above will be described with reference to the flowchart of FIG.

(1) First, the head substrate 1 having the heating elements 3 and the like which are patterned by the conventionally well-known thin film forming technique.
And the top plate 7 having the ink ejection holes 8 are arranged so as to face each other so as to form a predetermined gap therebetween, and the gap 9 is filled with the ink 9 to assemble the thermal inkjet head.

(2) Next, a predetermined power pulse (rated pulse) is applied to each heating element 3 on the head substrate 1 to eject the ink 9 from the ink ejection hole 8 and the ejection of the ejected ink 9. Measure speed.

The ejection speed of the ink 9 is determined by, for example, taking a series of photographs of the ink droplet i ejected from the ink ejection hole 8 in increments of 5 μsec, and determining the displacement amount from the position information of the ink droplet i recorded in these photographs. Is obtained by dividing the displacement amount by the time required for the measurement, and such a discharge speed is measured for all the heating elements 3.

(3) Next, the ejection speed of the ink drop i obtained in the step (2) is compared with a predetermined reference speed to obtain a speed difference between the two, and the ejection speed of the ink drop i is set as the reference speed. A predetermined trimming pulse required to bring them closer, that is, a trimming pulse corresponding to the speed difference is selected.

For example, when the reference speed is 9.0 m / s and the ejection speed of the ink droplet i is 8.5 m / s, the speed difference between the two is -0.5 m / s, and this speed difference (ejection speed-reference The trimming pulse corresponding to the speed) is obtained from FIGS. 4 and 5.

In this step, first, the resistance value correction width corresponding to the speed difference is obtained from the diagram (FIG. 4) showing the relationship between the "speed difference" and the "resistance value correction width", and then the "resistance value correction value" is calculated. The energy of the trimming pulse to be applied to the heating element 3 is obtained from the diagram (FIG. 5) showing the relationship between the “correction width” and the “energy of the trimming pulse”, and the trimming pulse closest to this is obtained by a plurality of previously prepared trimming pulses. One of the seed trimming pulses is selected.

When the ejection speed of the ink drop i is slower than the reference speed, the resistance value is corrected in the direction of decreasing it. Therefore, the diagram of FIG. When the ejection speed is higher than the reference speed, the resistance value is corrected in the direction of increasing it, and therefore the diagram of FIG. 5B is used.

(4) Finally, the conventionally known pulse trimming method, specifically, the trimming pulse selected in the step (3) is applied to the corresponding heating element 3 to change the electric resistance value of the heating element 3. The electric resistance value of the heating element 3 is adjusted by lowering or raising it.

The application of the trimming pulse to the heating element 3 is performed through the pad 5 of the power supply wiring 4 described above, and the probe 5 of the probing device is provided on the surface of the pad 5 as shown in FIG. Are brought into contact with each other, and in this state, the heating element 3 is trimmed by applying a predetermined trimming pulse selected in the step (3) from the probing device, whereby the electric resistance value of the heating element 3 is adjusted. .

In the pulse trimming method, for example,
The pulse width (energization time) is relatively short for the heating element 3,
By applying a trimming pulse having a relatively large amplitude (voltage value), the resistance material forming the heating element 3 is crystallized. In this case, the heating element 3 is annealed and a decrease phenomenon of the resistance value occurs.

On the other hand, when the resistance value of the heating element 3 is increased, a resistance material for forming the heating element 3 is applied by applying a trimming pulse having a relatively long pulse width and a relatively small amplitude to the heating element 3. Is combined with oxygen in the protective film 6 to form a thin oxide film on the surface, thereby increasing the resistance value.

At this time, the oxygen content in the protective film is 2.0.
Since it is set to mass% to 10.0 mass%, the amount of resistance variation when increasing the resistance becomes an appropriate amount, and it becomes easier to make finer resistance adjustment by the pulse trimming method. There are advantages.

Here, if the oxygen content in the protective film is less than 2.0% by mass, the degree of increase in the resistance value is too small, and there is the disadvantage that it takes a long time to adjust the resistance value.
If the oxygen content is greater than 10.0% by mass, cracks or the like may occur in the protective film, or the adhesion strength of the protective film tends to decrease. Therefore, it is preferable to set the oxygen content in the protective film to 2.0% by mass to 10.0% by mass.

After performing the above-mentioned trimming work, the resistance value of the trimmed heating element 3 is measured,
If the measured value is not sufficiently close to the target resistance value, the above trimming work is repeated until the resistance value falls within the allowable range.

In such trimming work, the resistance value may be adjusted only by decreasing or increasing the resistance value, or by both decreasing and increasing the resistance value. For example, only when the resistance value decreases, the heating element 3
When the resistance value adjustment is performed, the material and film thickness of the resistive thin film are selected so that the initial resistance value is set sufficiently higher than the target resistance value.

According to the adjusting method of the present embodiment as described above, it is possible to accurately correct the variation in the resistance value generated in the heating element 3 when the heating element 3 is formed by the thin film forming technique by pulse trimming. Therefore, the thermal energy generated by the heating element 3 and the ejection speed of the ink droplet i are substantially equalized, and a high-performance thermal inkjet head capable of forming a clear image with less distortion can be obtained.

Further, in this case, since the heat energy generated by each heating element 3 is made uniform by adjusting the resistance value of the heating element 3, the correction data is stored as compared with the case where the applied power is adjusted using the correction data. No memory, complicated correction circuit, power supply circuit, etc. are required, and the structure of the thermal inkjet head and the printer body in which it is installed can be simply maintained, and no correction processing during recording operation is required. Therefore, it is possible to obtain a high-performance thermal inkjet head that can easily cope with the increase in recording speed.

Further, according to the above-mentioned resistance value adjusting method, the probe 1 of the probing device is applied when the trimming pulse is applied.
Since the pad 5 of the power supply wiring 4 for contacting 0 is provided outside the filling area of the ink 9, the probe 10 of the probing device can be surely brought into contact with the pad 5 even after the thermal inkjet head is assembled. There is also an advantage that the trimming can be easily performed and the workability of the trimming can be improved.

The present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the gist of the present invention.

For example, in the above embodiment, a partition member for separating the adjacent heating element 3 is interposed between the head substrate 1 and the top plate 7, or such a partition member is integrated with the top plate 7. You may make it form in.

Further, in the above-mentioned embodiment, the ink discharge hole 8 of the top plate 7 is positioned directly above the corresponding heating element 3, but instead of this, the ink discharge hole is directly above the heating element. The present invention may be applied to a thermal inkjet head of an edge shooter type, which is arranged more staggered or ejects ink droplets from the edge of the head substrate.

Further, in the above embodiment, the trimming pads 5 are arranged in a line in the main scanning direction, but instead, the trimming pads 5 are arranged in a staggered pattern in the main scanning direction. This may be done, and in this case, there is an advantage that a space can be provided between the adjacent pads and a short circuit between the adjacent power supply wirings and pads can be effectively prevented.

Further, in the above-described embodiment, the resistance value correction width is first obtained from the speed difference between the ink droplet ejection speed and the reference speed, and then the trimming pulse is obtained from the obtained resistance value correction width. However, instead of this, a table or the like showing the relationship between the speed difference between the ink drop ejection speed and the reference speed and the trimming pulse is prepared in advance, and trimming is performed from the speed difference using such a table. The pulse may be determined directly.

[0064]

According to the adjusting method of the present invention, it is possible to accurately correct the resistance value variation occurring in the heating element when the heating element is formed by the thin film forming technique by pulse trimming. The thermal energy emitted and the ejection speed of ink are substantially equalized, and a high-performance thermal inkjet head capable of forming a clear image with less distortion can be obtained.

Further, according to the adjusting method of the present invention, the electric resistance value of the heating element is adjusted to equalize the thermal energy generated by the heating element. Therefore, the applied power is adjusted using the correction data. In comparison with the case, a memory for storing correction data, a complicated correction circuit, a power supply circuit, etc. are not required, and the structure of the thermal inkjet head and the printer body in which it is installed can be simply maintained, and at the same time, during the recording operation. Since no correction processing is required at all, it is possible to obtain a high-performance thermal inkjet head that can easily cope with an increase in recording speed.

Further, according to the adjusting method of the present invention, since the heating element to which the trimming pulse is applied is covered with the protective film made of the inorganic material containing silicon and oxygen,
By reacting part of the heating element with oxygen in the protective film to form a thin oxide film on the surface of the heating element, it becomes possible to increase the resistance value of the heating element. It is possible to correct both up and down.
Therefore, when adjusting the resistance value, the target resistance value can be set so that the maximum value of the energy of the trimming pulse applied to the heating element becomes small, and the heating element becomes excessively hot when the trimming pulse is applied. It is possible to effectively prevent the heat loss of the heating element due to the above.

Furthermore, according to the adjusting method of the present invention, the resistance when a predetermined trimming pulse is applied is set by setting the oxygen content in the protective film to 2.0% by mass to 10.0% by mass. There is also an advantage that the degree of increase in the value becomes an appropriate size, and finer resistance value adjustment becomes possible.

Furthermore, according to the adjusting method of the present invention, by applying the trimming pulse to the heating element via the trimming pad provided in the middle of the power supply wiring and outside the ink filling area, Even after assembling the thermal inkjet head, the probe (probe) of the probing device used for applying the trimming pulse can be surely and easily brought into contact with the pad for trimming. There is also an advantage that the workability of trimming becomes good.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a thermal inkjet head obtained by an adjusting method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the inkjet head of FIG.

FIG. 3 is a flowchart illustrating an adjusting method according to an exemplary embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a “speed difference” and a “resistance value correction width”.

FIG. 5A is a diagram showing a relationship between a “resistance value correction width” and a “trimming pulse energy” when the resistance value is decreased, and FIG. 5B is a “resistance value” when the resistance value is increased. It is a diagram which shows the relationship between "correction width" and "energy of a trimming pulse."

FIG. 6 is a sectional view for explaining a trimming operation.

FIG. 7 is a cross-sectional view of a conventional thermal inkjet head.

[Explanation of symbols]

1 ... Head substrate, 2 ... Base plate, 3 ...
・ Heating element, 4 ・ ・ ・ Power supply wiring, 5 ・ ・ ・ Pad, 6 ・
..Protective film, 7 ... Top plate, 8 ... Ink ejection hole, 9
... Ink, 10 ... Probing device probe, A
... Bubbles, i ... Ink drops

Claims (4)

[Claims] 1. A predetermined gap is provided between a plurality of heating elements made of a resistive thin film and a power supply wiring electrically connected to the heating elements on an upper surface of a base plate. A thermal ink jet head that forms an image by ejecting the ink filled in the gap from the ink ejection holes by the thermal energy generated by the heating element, A method for adjusting a resistance value of a thermal inkjet head, wherein the electric resistance value of the heating element is adjusted through the following steps 1 to 3. (Step 1) A step of applying a predetermined power pulse to each heating element to eject ink from the ink ejection hole and measuring the ejection speed of the ejected ink. (Step 2) A step of comparing the ink ejection speed measured in step 1 with a predetermined reference speed to obtain a speed difference between the two, and selecting a trimming pulse corresponding to the speed difference. (Step 3) A step of applying the trimming pulse selected in Step 2 to the corresponding heating element to adjust the electric resistance value of the heating element. 2. The heating element is covered with a protective film made of an inorganic material containing silicon and oxygen, and a part of the heating element to which a trimming pulse is applied reacts with oxygen in the protective film to generate a heating element. The resistance value adjusting method for a thermal ink jet head according to claim 1, wherein an oxide film is formed on the surface of the heating element, and the resistance value of the heating element is increased to adjust the resistance value. 3. The oxygen content in the protective film is 2.0 mass%.
The method for adjusting the resistance value of a thermal ink jet head according to claim 2, wherein the resistance value is set to -10.0 mass%. 4. A trimming pulse is applied to a corresponding heating element via a trimming pad provided outside the ink filling area in the middle of the power supply wiring. Item 4. A method for adjusting a resistance value of a thermal inkjet head according to any one of Items 3.