JPH06238901A - Ink-jet recording device - Google Patents

Abstract

PURPOSE:To aim at performing a sharp improvement in thermal efficiency and sharp reduction in mounting cost by relating to a recording device which is in a style to let ink drop fly toward a recording medium by heating a pulse. CONSTITUTION:A plurality of heating resistors 3 comprised of a Cr-Si-Sio alloy thin film resistor 3 and Ni thin film conductors 4, 5 which are joined to a driving LSI chip l comprised at least of a shift register circuit, latch circuit and driver circuit, are formed on the driving LSI chip 1 and an ink flow path 23 with an orifice 24 and a common ink supply chamber 22 supplying ink to the ink flow path 23 are provided on the respective heating resistors 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus of a type in which thermal energy is used to eject ink droplets toward a recording medium.

[0002]

2. Description of the Related Art An ink jet recording apparatus of a type in which a part of ink is rapidly vaporized by pulse heating and an ink droplet is ejected from an ink ejection port by its expansive force is disclosed in JP-A-48-9622. . The simplest method of pulse heating is to energize the heating resistor with a pulse, and a specific method thereof is disclosed in Japanese Patent Laid-Open No. 54-599.
No. 36, or a hard copy advanced technology research group sponsored by Japan Industrial Technology Promotion Association (held on February 26, 1992), or Hewlett-Packard Jou.
rnal, Aug. Published in 1988. The common basic configuration of these conventional heating resistors is that the thin-film heating resistor and the thin-film conductor are covered with an anti-oxidation layer, and the anti-cavitation layer is 1 to 2 in order to protect the anti-oxidation layer from cavitation damage. It was a layer coating.

As a drastic simplification of this, as described in Japanese Patent Application No. 4-138498, there is a method of printing using a heating resistor which does not require the antioxidant layer and the cavitation resistant layer. . Since the thin film heating resistor of the heating resistor is in direct contact with the ink, the vaporization of the ink by pulse energization and the ink ejection performance due to it are significantly improved, and the thermal efficiency is greatly improved (30 to 60 times). I was able to get Furthermore, by making the shape of the thin-film heat generating resistor asymmetrical, it becomes possible to give directionality to the generation of bubbles, and the ink ejection frequency can be increased 1.2 to 1.3 times.

An ink flow path with an orifice is provided on these heating resistors, and the orifice has a density of, for example, 400 dpi (dots / inch), for example, 64.
The print heads are arranged in a straight line. Since ink is ejected from the orifice of the ink flow path having the heating resistor which is pulse-energized among these 64 orifices, on-demand recording is performed by scanning the print head by the width of the recording paper. Of.

To drive this printhead, 64
It is necessary to energize each of the heating resistors with a pulse, and 65 wires including the common ground wire are indispensable. A specific mounting method for this purpose is a method in which a substrate on which a heating resistor is formed is adhered to a heat sink and the printed circuit board adhered on the same heat sink is electrically connected by a wire bonding method.
When a drive LSI is mounted on this printed circuit board, the connection between this printed circuit board and an external circuit is usually 7-8.
Book wiring is sufficient. That is, the connection between the print head on which the driving LSI is mounted and the recording apparatus main body is 7
It is connected by ~ 8 wires, and in this state the head runs left and right by the width of the recording paper.

By the way, almost all of recent ink jet recording apparatuses have a replaceable print head system,
The boundary is a contact connecting portion between the printed circuit board and an external circuit. In the above example, since the drive LSI is mounted on the printed circuit board on the replacement side, this LS
I will also be discarded, but the number of contact points is 7
There is an advantage that it is as small as ~ 8 points. On the other hand, if the drive LSI is mounted on the recording device main body side and not discarded,
The number of contact connection points is very large at 65 points, which is disadvantageous in that the printed circuit board and the contact connection portion are considerably large. And, whichever method is used, 62
It is necessary to connect the printed circuit board and the board of 64 heating resistors formed with a high density of μm pitch. Therefore, in order to improve this, a method of forming a heating resistor and a diode on the same silicon substrate and separately driving them is disclosed in JP-A-57-72867 and JP-A-57-7286.
No. 8 publication. Although the number of connection points can be reduced to 1/4 by this method, 16 or more wire bondings and contact points are still required. In the divided driving, for example, 8 dots are divided into 8 times for driving. Therefore, if the pulse energization time for one time is 10 μs, it takes 80 μs to drive 64 nozzles. Furthermore, this repetition cycle is 250 μs (4 kHz)
And the head travels at a constant speed.
Dots are shifted by 10/250 dot width in units of 8 dots. Therefore, the uppermost 8 dots and the lowermost 8 dots are printed with a shift of about 20 μm, which is 28% of the dot width. This 6
In the case of a 4-dot head, this deviation is not noticeable, but in the case of a 256-dot head, it is necessary to correct it, and it is necessary to incline the head or make the head travel stepwise.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the number of wire bonds and the number of contact points of a replaceable printhead to 7 to 8 points, and to significantly improve the thermal efficiency and the manufacturing cost of the printhead. Another object of the present invention is to provide an ink jet recording apparatus which is reduced in number and has a higher density and a larger number of orifices.

[0008]

The above object is to provide a Cr-Si-SiO alloy thin film resistor and Ni connected to a drive LSI chip which is composed of at least a shift register circuit, a latch circuit and a driver circuit. An ink jet recording apparatus in which a plurality of heat generating resistors made of thin film conductors are formed, and ink flow channels with orifices and a common ink supply chamber for supplying ink to the ink flow channels are provided on each heat generating resistor. It is achieved by

[0009]

A driver circuit is already connected to each heating resistor of the ink jet recording apparatus configured as described above,
A signal indicating whether or not to operate each driver circuit is sequentially transmitted and stored by the shift register circuit and the latch circuit, and can be collectively driven at a determined timing. These three circuits and the heating resistor are formed on the same silicon substrate, and the signal lines necessary for operating these circuits are the driver, stroke, clock,
There are 7 to 8 latches, power supplies, grounds, IC power supplies, and the like. That is, in the prior art, for example, 16 (divisional drive) to 65 (collective drive) signal lines were required to operate 64 heating resistors, but according to the present invention, 7 to 7 even in collective drive. Since only eight wires are required, the number of wire bondings and the number of contact points can be greatly reduced to 7 to 8, respectively. This situation does not change even if the arrangement density of the orifices becomes high and the total number of orifices (heating resistors) increases. However, when the number of orifices is extremely increased, the current that flows in collective driving becomes large, so that division driving is performed, but in this case, the stroke signal line only increases by the number of blocks according to the number of blocks. In addition, the thin-film heating resistor of the present invention having no protective layer has a very high thermal efficiency, and the input power is as small as 1/30 to 1/60 of the conventional technique. Therefore, the amount of heat radiated to the silicon substrate is 1/30 to 1/60 or less of that of the conventional technique, and the temperature of the silicon substrate cannot be raised. That is, it is not necessary to provide any heat insulating area between the driving LSI and the heat generating resistor, and they may be placed close to each other. As is clear from the above description, the cost of a driving LSI having a heating resistor that does not require a protective layer is lower than that at the chip stage (single chip), and the heating resistor that was indispensable in the conventional technology No wire bonding (16 to 65 wires) and wire bonding (65 + 7 wires) for the driving LSI are also required, and the printed board on which the driving LSI is mounted is also unnecessary, and a significant reduction in mounting cost is achieved.

[0010]

EXAMPLES Examples will be described below with reference to the drawings.

[Embodiment 1] First, a driving L of 64 dots
A method of manufacturing the SI-embedded thermal inkjet printhead will be described with reference to FIG.

For example, a 64-dot drive LSI including a shift register circuit, a latch circuit, and a driver circuit is formed on the Si wafer 1 by a semiconductor process of a rule of 2 to 3 μm. Cr-Si-SiO / Ni is formed on top of this by a normal thin film formation process (sputtering and photo etching, etc.).
The heating resistor 3 for 64 dots of the two-layer structure 3 and 4, 5 is formed. However, the heating resistor 3 is laminated on the silicon substrate 1 at a position adjacent to the driving LSI and has a thickness of 2 to 3 μm.
The heating resistors 3 are formed on the m-thick SiO ₂ insulating layer 2 so as to be connected to the corresponding driver circuits at the through-hole connecting portions 11. This C
The r-Si-SiO / Ni two-layered heating resistor is a patent application invention of the present inventors (Japanese Patent Publication No. 4-4721, Japanese Patent Publication No. 4-721).
No. 60835, Japanese Patent Application No. 4-138498). Although not shown in FIG. 1,
A Ta ₂ O ₅ layer (not shown) having a thickness of about 1500Å is formed as an etching resistant layer between the SiO ₂ insulating layer 2 and the Cr—Si—SiO alloy thin film resistor 3. Further, no protective layer is coated on the periphery of the heating resistor 3 including the Ni thin film conductors 4 and 5, but the passivation of the driving LSI or the stray from the Ni thin film conductor in the vicinity of the through hole connection portion 11 to the aqueous ink. In some cases, it may be effective to coat a protective layer to prevent the generation of electric current.
It may be coated with O ₂ or a polyimide resin.

In this way, the heating resistor and the driving LSI
An ink supply chamber 22, an ink flow path 23, and an orifice 24 are formed on the Si wafer on which the ink is formed. To this, a partition wall 6 such as the ink flow path 23 is first formed with a thick photoresist or a photosensitive polyimide, and a PET film or the like is adhered thereto with an ultraviolet curing resin or the like to form the top plate 7,
If necessary, holes or orifices (24 in FIG. 3) in the ink supply chamber 22 can be formed by using photoetching or an excimer laser processing method.

Finally, by cutting this silicon wafer and dividing it into chips, 64-dot thermal ink jet print head chips (FIG. 1) are completed. Adhere this chip to the substrate for temperature control and contact,
It is electrically connected with eight wire bonds. on the other hand,
The ink supply path 21 is connected to the ink supply chamber 22 of this chip through the filter 8 and is connected to the ink tank at the rear side thereof, but it is omitted here.

As can be seen from the above description, the 64-dot driving LSI and the thermal ink jet print head are integrated into one chip, and 46 to 135 wires are required in the prior art for wire bonding (for driving). The number of contact contacts required for 16 to 65 contacts has been reduced to 7 to 8 contacts (including LSI). This is an example of a 64-dot thermal inkjet printhead. In the case of 256-dot, 86 to 520 wire bonds and 32 to 257 contact points were required, and 8 to 10 and 8 to 8 respectively. Since the number is 10, the mounting cost cannot be reduced. Needless to say, the magnitude of these cost reductions far exceeds the replacement cost of the drive LSI. It should be noted that FIG. 1 assumes a head of 400 dpi (dots / inch), and the arrangement of the orifices 24 in FIG. 1B is about 62 μm pitch. It is easy to perform through-hole connection (11) at this pitch, but conventionally, the Ni thin film conductors 5 lined up at the 62 μm pitch were connected to the external connection printed circuit board by wire bonding, which is a very difficult work. Become. At higher densities, there is no choice but to expand this array, and it can be understood from this point that the effectiveness of the one-chip implementation of the present invention is high.

Needless to say, when this thermal ink jet print head was incorporated into the carriage of a serial printer and printing was evaluated, clear printing could be achieved. Here, the performance data of the head will be described in detail and will be compared with the prior art.

Table 1 shows the characteristics of the head of the present invention and the prior art.
Here, the data of the head A and the head B which are published in academic societies and literatures are described.

[0018]

[Table 1]

Although the volume of the ejected ink is almost the same, this is because the print density is almost the same as 360 to 400 dpi. The ejection speed of B is extremely high. This is because the head of B adopts the structure of FIG. 3 described later, and the energy of the generated bubbles can be effectively used. Therefore, it is considered that the bubble generation energies necessary for ejecting the same volume of ink droplets are about the same, and therefore the difference in the input energy in Table 1 depends on the presence or absence of the oxidation protection layer and the cavitation protection layer. That is, the energy required to eject the ink droplets is 0.5 μJ / drop or less, and 99% of the input energy of A and B is used for heating the protective layer and the substrate. It is one of the major features that the cooling of the head of the present invention is so small that it can be said that it is unnecessary, and that the temperature control of ink is facilitated. Needless to say, the head of the present invention withstood a continuous operation of 1 billion pulses with double over-energization energy and no change was observed.

Next, regarding the comparison of the number of contact points of the head, the head of the present invention is a one-chip head in which a driving LSI is built on the same silicon substrate as the heat generating resistor as already described. This drive LSI is a shift register circuit having the same configuration as that of the thermal print head drive LSI,
It is composed of a latch circuit and a driver circuit, and the number of wires for collectively driving the heating resistors of 64 nozzles is
Stroke, clock, latch, power supply, ground, IC
There are seven power supplies. In contrast, in the case of B, contacts from each of 30 nozzles and two contacts of the common ground (one contact is also possible) are required, and a total of 32 contacts are used for contact connection of the head and the carriage. On the other hand, in the case of A, a diode is formed on the same silicon substrate as the heat generating resistor, and 8 × 8 block driving can be performed. That is, since a diode for preventing backflow is connected to each of the heating resistors and 8 nozzles are driven separately in 8 times, the number of wirings (the number of contacts) required for driving is 1
There are six. The remaining 16 wires are used for temperature measuring terminals of the head, etc., but in the case of the head of the present invention, the input energy is 1/60 of A, and the amount of heat flowing out to the substrate is further reduced, so the temperature No need for measurement. Also,
When the input power is reduced by almost an order of magnitude, the load on the driving LSI is significantly reduced, and an inexpensive LSI can be used.

[Embodiment 2] FIG. 2 shows a case where a heat generating resistor for ink supply is provided in Embodiment 1. The manufacturing method, mounting method, and driving method of this head are exactly the same as in the first embodiment. However, the applied energy and the ejection frequency are 0.7 μJ / drop and 10 to 15 kHz, respectively, and the printing speed of 2 to 3 times can be achieved.

[Embodiment 3] FIG. 3 shows an embodiment of a thermal ink jet print head when the ejection heater surface and the ink ejection direction are perpendicular to each other. The manufacturing method, mounting method, and driving method of this head are the same as those of the first embodiment, but the feature is that the passivation of the driving LSI portion is significantly superior to those of the first and second embodiments. That is, with respect to the common electrode 4 and the ink having the same potential, most of the individual electrodes 5 having the highest potential and the drive LSI units 10 and 11 are made of a thick photoresist or a photosensitive polyimide having excellent ink resistance. It is covered with the partition wall 6 and is completely separated from the ink.

This indicates that the head shown in FIGS. 1 and 2 is incomparably superior in terms of reliability, and the passivation cost of the driving LSI portion can be reduced accordingly. Becomes In this embodiment, the partition 6 is used to form the driving LSI units 10 and 11 and the individual electrode 5.
Although it covers part of the drive LSI unit 10,
If the head structure is such that 11 and a part of the individual electrode 5 are outside the ink passage, the same effect as that of this embodiment can be obtained. Of course, also in the case of the head shown in FIGS. 1 and 2, it is possible to retreat the drive LSI units 10 and 11 to a large extent and install them in the rear partition of the ink supply chamber 22. However, in this case, the head size may be slightly increased, and passivation or the like may be required to prevent the occurrence of leaks between the long individual electrodes 5 that are adjacent to each other in the ink supply chamber. Will be raised.

Although the head shown in FIG. 3 is provided with the ink supply heating resistor 12, the head without the ink supply heating resistor 12, that is, only with the ejection heating resistor is applied to the present invention. It goes without saying that you can do it.

The head shown in FIG. 3 is filled with an aqueous ink,
When printing was performed by inputting pulse energy of 0.7 W / pulse and applied pulse width of 1 μs, the ink ejection speed was about 12 m / s, which was the same value as that of head B in Table 1, and the ejection frequency was 8 to 13 KHz. Achieved

[0026]

According to the present invention, since the heating resistor without the protective layer and the driving LSI are formed on the same silicon substrate into one chip, the input energy required for ink ejection can be reduced to 1 / th of that of the prior art. It can be reduced to 30 to 1/60, and not only thermal insulation with the driving LSI but also temperature control including cooling of the entire head can be facilitated. Furthermore, it has been possible to achieve a significant reduction in the number of wire bondings and contacts (one-third to one-tenth) and a reduction in mounting cost associated with the one-chip implementation.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing another embodiment of the present invention.

FIG. 3 is a schematic sectional view showing another embodiment of the present invention.

[Explanation of symbols]

1 is a silicon substrate, 2 is a SiO ₂ insulating layer, 3 is Cr-S
i-SiO alloy thin film resistor (heater for discharge), 4 is Ni
Thin film conductor (common electrode), 5 Ni thin film conductor (individual electrode), 6 partition wall, 7 top plate, 8 filter, 9 ink supply channel wall, 10 diffusion layer, 11 through hole connection part,
Reference numeral 12 is a Cr-Si-SiO alloy thin film resistor (pumping heater), 21 is an ink supply path, 22 is an ink supply chamber, 23 is an ink flow path, and 24 is an orifice.

Claims (8)

[Claims] 1. A plurality of heating resistors made up of a Cr—Si—SiO alloy thin film resistor and a Ni thin film conductor provided on a part of a drive LSI chip, and the heating resistor for ejecting ink droplets. An orifice provided in the vicinity of the body, an ink passage communicating with the orifice, in which the heating resistor is disposed, and an ink supply chamber communicating with the ink passage for supplying ink. Characteristic ink jet recording device. 2. The ink jet recording apparatus according to claim 1, wherein the drive LSI chip includes at least a shift register circuit, a latch circuit, and a driver circuit. 3. The ink jet recording apparatus according to claim 1, wherein the orifice is arranged such that the heat acting surface of the heating resistor and the ink ejection direction are parallel to each other. 4. The ink jet recording apparatus according to claim 1, wherein the orifice is arranged such that the heat acting surface of the heating resistor and the ink ejection direction are perpendicular to each other. 5. The ink jet recording apparatus according to claim 1, wherein a heat generating resistor for ink supply is provided closer to the ink supply chamber than the heat generating resistor in the ink passage. 6. A Cr—Si—SiO alloy thin film resistor provided on a driving LSI chip having a driving LSI portion, one end of the Cr—Si—SiO alloy thin film resistor and the driving LSI portion. The individual electrode electrically connected to the C
A plurality of heating resistors, each of which is composed of a common electrode electrically connected to the other end of the r-Si-SiO alloy thin film resistor, and facing a heat acting surface of the heating resistor for ejecting ink droplets. And an ink passage which is constituted by a partition wall and is communicated with the orifice and in which the heating resistor is disposed, and an ink supply chamber which is communicated with the ink passage for supplying ink. And the drive LSI unit is arranged so as to be on the opposite side of the heating resistor from the position where the ink supply chamber is arranged, and the drive LSI unit and a part of the individual electrode are The ink jet recording apparatus, wherein the partition wall is arranged outside the ink passage. 7. The ink jet recording apparatus according to claim 6, wherein the drive LSI portion and a part of the individual electrode are covered with a surface of the partition wall facing the drive LSI chip. 8. The ink jetting device according to claim 6, wherein a heating resistor for ink supply is provided in the ink passage between the ink supply chamber and a heat acting surface of the heating resistor. Recording device.