JPH106503A - Substrate for ink jet recording head, ink jet recording head and recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set the foaming voltage of a large size heating resistor to the same value as a small size heating resistor, in an apparatus wherein electrode wiring and two heating resistors different in size are formed on a heat accumulation layer, by forming a protective film of the large size heating resistor, having thickness locally smaller than that of a protective film of the small size heating resistor. SOLUTION: In producing a substrate of a heating part, an Si substrate 120 is used and a heat accumulation layer 106 is formed on the lower part of a heating resistor by a thermal oxidation method. Next, a TaN layer 107 and Al layers 103, 104 are formed by reactive sputtering. Subsequently, a wiring pattern is formed by a photolithographic method and, after Al is removed by wet etching, the pattern is again formed and TaN is removed by reactive ion etching and an Al electrode and a heating resistor part 102 are formed. Succeedingly, a PSG layer 109 covering the Al electrode is formed by a CVD method and only the PSG layer of a smaller heating resistor part is removed by wet etching and an SiN layer 108 is subsequently formed by a CVD method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head and, more particularly, to an ink jet recording head which performs recording by discharging ink from discharge ports by growth and shrinkage of bubbles generated in ink by a discharge energy generating element.

[0002]

2. Description of the Related Art The ink jet recording system described in U.S. Pat. No. 4,723,129 or U.S. Pat. No. 4,740,796 enables high-speed, high-density, high-precision, high-quality recording, and is suitable for colorization and compactness. And
In recent years, it has attracted particular attention. In a typical example of an apparatus using this method, a recording liquid or the like (hereinafter, referred to as ink)
There is a heat acting portion for applying heat to the ink in order to eject the ink using heat energy. That is, an electrothermal converter having a pair of wiring electrodes and a heating resistor layer connected to these wiring electrodes and generating heat in a region between the wiring electrodes is provided corresponding to the ink flow path. The thermal energy generated from the heating resistor layer is used to rapidly heat and foam the ink on the heat acting surface, and the ink is discharged by the foaming.

Meanwhile, the heat-acting surface of an ink jet recording head is exposed to mechanical shock caused by cavitation due to repetition of foaming and defoaming of ink, erosion, and an extremely short time of 0.1 to 10 μsec. A protection layer is provided to protect the heating resistor layer from the environment in which it is used, because it is placed in a harsh environment such as being exposed to a temperature rise and fall of about 1000 ° C. per hour. The protective layer is required to have excellent heat resistance, liquid resistance, liquid permeation preventing properties, oxidation stability, insulation properties, damage resistance and thermal conductivity, and inorganic compounds such as SiO ₂ or SiN are generally used. It is used regularly. Furthermore, a single-layer protective film may not be sufficient for the performance of protecting the heat-generating resistor body layer, and a metal layer such as Ta having higher cavitation resistance may be formed on the protective film.

[0004] The above-mentioned structure is adopted in a wiring pattern for making an electrical connection with the heating resistor, for example, in addition to the heating resistor portion, in that case, in order to prevent the wiring from being corroded by the ink.

In an ink jet recording head, an HB substrate (heater board substrate) having a heat acting surface is formed in this manner, and the structure of the protective film determines the performance of the ink jet recording head, for example, power consumption and life. It is an important factor to determine.

On the other hand, conventionally, the concept of one heating element for one nozzle has been generally used. However, in order to provide gradation characteristics as a means of improving image quality, two nozzles are provided for one nozzle. The idea is to arrange large and small heating resistors. That is, a large heat generating resistor gives a large foaming energy to the ink to obtain a large discharge amount, and a small heat generating resistor gives a small foaming energy to the ink to obtain a small discharge amount, and by combining them, By obtaining a larger ejection amount, gradation is provided.

[0007]

However, the large and small heating resistors have the following drawbacks in terms of layout.

When arranging large and small heat generating resistors in one nozzle, it is necessary to arrange a small sized resistor in front of a large sized resistor in order to increase the arrangement pitch of the resistors. is there. In order to effectively use a small-sized resistor in a limited inter-nozzle pitch in terms of layout, it is desirable that the small size be closer to a square. In addition, in the case of a large-sized resistor, a narrow rectangular shape can obtain high power at a limited pitch between nozzles. Accordingly, since the small size is close to a square and the large size is a rectangle, a deviation of the foaming voltage Vth occurs. That means that two drive voltages are required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate for an ink jet recording head capable of equalizing the value of a foaming voltage Vth for foaming ink of two large and small heating resistors as described above. It is an object of the present invention to provide an ink jet recording head and a recording apparatus which can perform good recording by incorporating the above.

[0010]

According to the present invention, a heat storage layer is formed on a substrate, and a large-sized heating resistor and a small-sized heating resistor corresponding to one electrode nozzle and one nozzle of an ink jet recording head are formed on the heat storage layer. In a substrate for an ink jet recording head in which a resistor is formed and a protective film is formed on the substrate on which the heat generating resistor is formed, the protective film on the large-sized heat generating resistor is locally formed. Specifically, the present invention provides a substrate for an ink jet recording head, which is thinner than a protective film on an upper layer of the small-sized heating resistor; an ink jet recording head incorporating such a substrate; and a recording apparatus including the head.

That is, according to the present invention, of the large and small heating resistors, the upper protective film on the large heating resistor is partially thinned to reduce foaming of the large heating resistor. Energy efficiency can be increased, and the foaming voltage Vth can be set to the same value as a small-sized heating resistor.

Alternatively, by partially reducing the thickness of the lower heat storage layer of the heat generating resistor on the small side, heat dissipation in the downward direction is increased, the energy efficiency of foaming is reduced, and the foaming voltage Vth is increased by a large size. Can be set to the same value as that of the heating resistor.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a plan view of a substrate of a heating section for bubbling ink of an ink jet recording head according to an embodiment of the present invention, and FIG. 2 is a plan view of the substrate shown in FIG. FIG. 4 is a partial sectional view taken along a line X 1 -X 1 ′ taken along a dashed line and perpendicular to a substrate surface. FIG. 3 is a partial cross-sectional view when the substrate shown in FIG. 1 is cut perpendicular to the substrate surface along the dashed line X2-X2 '.

The production of the substrate of the heat generating portion according to the present embodiment is performed by S
An i-substrate 120 is used. The SiO _TwoThe substrate 120 includes
A driving IC may already be built. Si group
In the case of a plate, thermal oxidation, sputtering, CVD, etc.
The lower part of the heating resistor_TwoForming a heat storage layer of
Similarly, the substrate in which C has been formed can be made in the manufacturing process.
O_TwoIs formed in advance. In the figure, 106 is the part
Equivalent to a minute.

Next, a TaN layer 107 is formed as a heating resistor to a thickness of about 1000 ° by reactive sputtering, and Al layers 103 and 104 as an electrode wiring are formed to a thickness of 6000 ° by sputtering.

Next, the wiring pattern of FIG. 1 is formed by photolithography, Al is removed by wet etching, a pattern is formed again, TaN is removed by reactive ion etching, and an Al electrode and a heating resistor are formed. Body part 102
To form The end of the Al wiring extending from the Al electrode serves as a wire bonding pad in the case of a Si substrate, and is connected to a lower electrode through a through hole in the case of a substrate in which an IC is formed.

A PSG layer (phosphorous glass layer, hereinafter abbreviated as PSG layer) 109 as a film covering the Al electrode is formed by CVD.
The PSG layer of the smaller heating resistor is removed by photolithography using a wet etching method. Next, the SiN layer 108 is
Approximately 3000 ° is formed by the D method. As a result, a protective film of PSG 7000Å and SiN 3000 上 is formed on the Al wiring, and SiN 3000Å is formed on the heating resistor portion.
Is formed. As a result, a total of 10,000 １０ of the protective film is provided on the larger heating resistor shown in FIG. 3 and 3000 に は is provided on the smaller heating resistor shown in FIG.
Is formed, and the structure as shown in FIG. 1 is obtained.

Next, Ta as an anti-cavitation and anti-ink film is formed to a thickness of about 2500 ° by sputtering as shown at 110 in FIGS.

Finally, Ta is patterned by a photolithography method, and finally, a window for a wire bonding pad on which a PSG and a SiN layer are laminated is opened, and a substrate of a heat generating portion for foaming ink of an ink jet recording head ( 1) of FIG. 1 was produced.

In the substrate thus manufactured, the protective film on the large heating resistor of the two large and small heating resistors is thinner than the protective film on the small heating resistor. The value of the foaming voltage Vth for foaming the inks of the two heating resistors could be made uniform.

(Embodiment 2) FIG. 4 is a plan view of a substrate of a heating section for bubbling ink of an ink jet recording head according to a second embodiment of the present invention, and FIG. 5 is a plan view of the substrate shown in FIG. FIG. 3 is a partial view of a cut surface when the substrate is cut perpendicularly to the substrate surface along a dashed line Y1-Y1 '. FIG. 6 is a partial cross-sectional view when the substrate shown in FIG. 4 is cut perpendicularly to the substrate surface along the dashed line Y2-Y2 '.

The production of the substrate of the heat generating portion according to the present embodiment
An i-substrate 120 is used. A driving IC may be already built in the Si substrate 120.

In the case of a Si substrate, SiO ₂ is formed under the heating resistor by a thermal oxidation method, a sputtering method, a CVD method, or the like.
Is formed in advance. In the figure, 106 corresponds to that part.

Next, the heat storage layer of the large-sized heat generating resistor portion shown in FIG. 4 is locally dug by wet etching using a photolithography method. As shown in FIG. 5, in the excavated heat storage layer, the lower heat storage layer of the heating resistor portion is thinned.

Next, a TaN layer 107 is formed as a heating resistor to a thickness of about 1000 ° by reactive sputtering, and Al layers 103 and 104 as an electrode wiring are formed to a thickness of 6000 ° by sputtering.

Next, the wiring pattern of FIG. 4 is formed by photolithography, Al is removed by wet etching, a pattern is formed again, TaN is removed by reactive ion etching, and an Al electrode and a heating resistor are formed. Body part 102
To form The end of the Al wiring extending from the Al electrode serves as a wire bonding pad in the case of a Si substrate, and is connected to a lower electrode through a through hole in the case of a substrate in which an IC is formed.

Next, the SiN layer 108 as a protective film is
Then, a Ta layer 110 as a cavitation-resistant film is formed to a thickness of about 2500 ° by a sputtering method.

Next, using a photolithography method, Ta is patterned by dry etching. Subsequently, the SiN on the wire bonding pad is removed, and the substrate of the heat generating portion for foaming the ink of the ink jet recording head (see FIG. 4). 101) was produced.

In the substrate manufactured in this manner, of the two large and small heating resistors, the heat storage layer below the small heating resistor is locally thinner than the heat storage layer below the large heating resistor. The value of the foaming voltage Vth for foaming the inks of the two heating resistors could be made uniform.

When recording was performed using an ink jet recording head incorporating the substrates obtained in Examples 1 and 2 above, good recording excellent in gradation was obtained.

(Embodiment 3) The wiring of the large and small heating resistors shown in Embodiments 1 and 2 is not only shown in FIGS. 1 and 4, but also in large and small sizes as shown in FIG. Even if individual wiring is provided for each heating resistor having a size, it is possible to obtain a substrate having the same effects as those of the first and second embodiments.

(Embodiment 4) The wirings to the large and small heating resistors shown in Embodiment 1 are shown in FIGS. 8 and 9 (FIG. 8).
Sectional view when the substrate is cut perpendicularly along the line Z1-Z1 ')
When the vertically folded wiring is used as described above, the area occupied by the wiring in the horizontal direction is reduced, and the density can be further increased.

The present invention particularly provides an excellent effect in an ink jet recording head and a recording apparatus in which a flying liquid droplet is formed by utilizing thermal energy and recording is performed.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, liquid (ink)
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding nucleate boiling to an electrothermal transducer arranged corresponding to the sheet or liquid path in which This is effective because heat energy is generated in the electrothermal transducer, causing film boiling on the heat-acting surface of the recording head, and as a result, air bubbles in the liquid (ink) corresponding one-to-one to this drive signal can be formed. It is. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the ejection port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned respective specifications, The present invention also includes a configuration using U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose a configuration in which a heat acting portion is arranged in a bending region.

In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal transducer for a plurality of electrothermal transducers, or absorbs pressure waves of thermal energy. The present invention is also effective as a configuration based on JP-A-59-138461, which discloses a configuration in which an opening corresponds to a discharge unit.

Further, as a full line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is determined by a combination of a plurality of recording heads as disclosed in the above specification. The present invention can exhibit the above-mentioned effects more effectively, though it may be either a configuration that satisfies the above requirements or a configuration as a single recording head that is formed integrally.

In addition, the print head is exchangeable with a print head of a chip type, which can be electrically connected to the main body of the apparatus or supplied with ink from the main body of the apparatus, or is integrated with the print head itself. The present invention is also effective when a cartridge type recording head provided with an ink tank is used.

Further, it is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like provided as components of the printing apparatus of the present invention since the effects of the present invention can be further stabilized. If you list these specifically,
Capping means, cleaning means, pressurizing or suction means for the printhead, preheating means using an electrothermal transducer or another heating element or a combination thereof, and a preliminary ejection mode for performing ejection other than recording Is also effective for performing stable recording.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, and the recording head may be formed integrally or by combining a plurality of recording heads. The present invention is also extremely effective for an apparatus provided with at least one of full colors by color mixture.

In the embodiments of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or below and which softens at room temperature, or which is liquid, In general, in the ink jet method, the temperature of the ink itself is controlled within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. What is necessary is just to be liquid.

In addition, the temperature rise due to thermal energy can be positively prevented by using it as energy for changing the state of the ink from a solid state to a liquid state, or solidified in a standing state for the purpose of preventing evaporation of the ink. Either ink may be used, or in any case, the ink may be liquefied by application of heat energy according to the recording signal and ejected as a liquid ink, or may already start to solidify when reaching the recording medium. The use of an ink having a property of being liquefied for the first time by thermal energy is also applicable to the present invention. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as a form of the recording apparatus according to the present invention, in addition to those provided integrally or separately as an image output terminal of an information processing apparatus such as a word processor and a computer, a copying apparatus combined with a reader and the like, May take the form of a facsimile machine having a transmission / reception function.

[0047]

As described above, according to the present invention,
Two large and small heating resistors for foaming ink are arranged in one nozzle for ejecting ink, and the upper heating film of the large-sized heating resistor is locally thinned to form two heating resistors. In this manner, it is possible to obtain a substrate for an ink jet recording head which can make the value of the foaming voltage Vth for causing the ink to foam.

Alternatively, two large and small heating resistors for foaming ink are arranged in one nozzle for discharging ink, and the heat storage layer below the small-sized heating resistor is locally thinned. It is possible to obtain a substrate for an ink jet recording head that can make the value of the foaming voltage Vth for foaming the inks of the two heat generating resistors uniform.

By producing such an ink jet recording head by incorporating such a substrate for an ink jet recording head, it is possible to perform recording with excellent gradation.

[Brief description of the drawings]

FIG. 1 is a plan view of a heat generating substrate of an ink jet recording head according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the heat generating substrate when the heat generating substrate of FIG. 1 is cut vertically along a line X1-X1 '.

FIG. 3 is a cross-sectional view of the heat generating substrate when the heat generating substrate of FIG. 1 is cut perpendicularly along a line X2-X2 '.

FIG. 4 is a plan view of a heat generating substrate of an ink jet recording head according to a second embodiment of the present invention.

5 is a cross-sectional view of the heat generating substrate when the heat generating substrate of FIG. 4 is vertically cut along a line Y1-Y1 '.

FIG. 6 is a cross-sectional view of the heat generating substrate when the heat generating substrate of FIG. 4 is cut vertically along a line Y2-Y2 '.

FIG. 7 is a plan view of a heat generating substrate of an ink jet recording head according to a third embodiment of the present invention.

FIG. 8 is a plan view of a heat generating substrate of an ink jet recording head according to a fourth embodiment of the present invention.

9 is a cross-sectional view of the heat generating substrate when the heat generating substrate of FIG. 8 is cut perpendicularly along the line Z1-Z1 '.

FIG. 10 is a plan view of an example of a heat generating substrate of a conventional ink jet recording head.

[Explanation of symbols]

 Reference Signs List 101 Substrate on which heating resistor and electrodes are formed 102 Heating part (heater) 103 Al electrode 104 Al electrode 105 Partially thinned portion 106 Heat storage layer 107 Heating resistor layer 108 SiN protective film 109 PSG protective film 110 Ta 111 Lower layer Al electrode of upper and lower folded wiring 120 Si substrate

Claims (7)

[Claims] A heat storage layer is formed on a substrate, and a large-sized heating resistor and a small-sized heating resistor are formed on the heat storage layer in correspondence with electrode wiring and one nozzle of an ink jet recording head. In a substrate for an ink jet recording head, wherein a protective film is formed on a substrate on which the heat generating resistor is formed, a protective film on an upper layer of the large-sized heat generating resistor locally covers the small-sized heat generating resistor. A substrate for an ink jet recording head, which is thinner than a protective film on an upper layer of a body. 2. A heat storage layer is formed on a substrate, and a large-sized heating resistor and a small-sized heating resistor are formed on the heat storage layer in correspondence with electrode wiring and one nozzle of an ink jet recording head. In a substrate for an ink jet recording head in which a protective film is formed on a substrate on which the heating resistor is formed, a heat storage layer below the small-sized heating resistor is locally formed by the large-sized heating resistor. A substrate for an ink jet recording head, wherein the substrate is thinner than a lower heat storage layer of the body. 3. The substrate for an ink jet recording head according to claim 1, wherein the electrode wiring is a vertically folded wiring. 4. An ink jet recording head incorporating the substrate according to claim 1. 5. The ink jet recording head according to claim 4, wherein the ink ejection energy generating element is an electrothermal converter for generating heat by applying electric energy, causing a change in state of the ink to perform ejection. 6. The ink jet print head according to claim 4, wherein the print head is a full line type having a plurality of discharge ports provided over the entire width of a print area of a print medium. 7. An ink ejection port for ejecting ink facing a recording surface of a recording medium.
A recording apparatus, comprising: the recording head according to claim 1; and a member for mounting the recording head.