JPH08132623A - Ink jet recording head and ink jet recording apparatus - Google Patents

Abstract

PURPOSE: To obtain a small and inexpensive ink jet recording head of high reliability not generating the non-emission of ink by integrally providing the small chamber in which air is housed communicating with a common liquid chamber through a communication part to a top plate and setting the surface direction of the communication part so as not to cross an ink passage. CONSTITUTION: When a protruding part 306 is provided to the rear part of the common liquid chamber 302 of a top plate 300, the contact part of a heater board 200 and the top plate 300 becomes a plurality of ink passage walls 307 forming the protruding part 306 and a plurality of ink passages 308 and, therefore, the close adhesiveness of the ink passage walls 307 and the heater board 200 is improved and ink is stably emitted. Bubble cells 310 for absorbing the pressure at the time of the emission of ink to stabilize the same are provided in the common liquid chamber 302 so as to be integrated with the top plate 300. The cells 310 are arranged at the positions most separated from a plurality of ink emitting orifices 301 and allowed to communicate with the common liquid chamber 302 through minute communication parts 311. Since the surface direction of the minute communication parts does not cross the row of the ink passages 308, it is suppressed that the air bubbles grown using the air bubbles in the cells 310 as nuclei reach the vicinity of the ink passages 308 directly.

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 for recording ink on a recording medium by ejecting ink from the recording head to the recording medium and an ink jet recording apparatus using the same. Here, the recording includes the application of ink (printing) to all the ink supports to which ink is applied, such as cloth, paper, thread, and sheet material, and the present invention can be applied to these. is there.

[0002]

BACKGROUND ART Among various currently known recording methods, it is a non-impact recording method that generates almost no noise during recording, enables high-speed recording, and does not require special fixing on plain paper. It is recognized that the inkjet recording method that can perform recording on is extremely effective.

7 and 8 show the essential parts of a typical ink jet recording head used in such an ink jet recording system. FIG. 7 is a schematic perspective view.
FIG. 8 is an exploded perspective view. FIG. 9 is a schematic sectional view showing the internal structure of the ink jet recording head taken along the plane XX of FIG.

Reference numeral 100 in the figure denotes a base plate for constructing and configuring each component (described later). A substrate (hereinafter referred to as a heater board) 200 having a plurality of electrothermal converters (heaters) 201 as discharge energy generating elements is provided on the base plate 100. Ink paths (not shown) corresponding to each of the plurality of ink ejection ports 301 are provided on the heater board 200, and the top plate 300 is joined at a predetermined position. The top plate 300 has an orifice plate 304 having an ink ejection port 301 formed therein, a common liquid chamber 302 for storing ink to be supplied to the ink path, and a cylindrical shape for supplying ink to the common liquid chamber 302. It has an ink supply port 305. At the time of joining, the top plate 300 is temporarily fixed to the heater board 200 with an adhesive at a position where the plurality of heaters 201 of the heater board 200 and the ink discharge ports 301 on the top plate 300 side correspond to each other, and the biasing force is further applied. A top plate 30 is provided by a spring (not shown) for giving
0 Mechanical pressure is applied from the top to obtain a sufficient adhesion state. After that, the periphery of the top plate 300 and the heater board 200 is sealed with a sealant 400 as shown in FIG. 9, and the ink path and the common liquid chamber 302 are sealed off from the outside.

The pressure for ejecting ink in the ink jet recording head is generated by the energy generated in the heater 201 acting on the ink in the ink passage 308, and the pressure is generated through the ink in the ink passage 308 through the ink ejection port 301. Direction to the common liquid chamber 302, which is opposite to the ink ejection port 301.

By the action of the pressure transmitted to the ink ejection port 301, the ink in the ink path 308 is pushed out from the ink ejection port 301, and the ejected ink forms flying ejection droplets. When the ejected ink becomes ejection droplets and leaves the ink ejection opening 301, the meniscus of the ejection opening 301 part retreats according to the ejection droplet amount, and the tension of the tension that tries to pull back this meniscus toward the ink ejection opening 301 is increased. By the action, the filled state of the ink in the ink path is restored to the state before the ejection after a certain period of time. This phenomenon is called refill. In the actual recording, by repeating the above operation and performing a good refill,
Stable ink ejection can be obtained continuously.

However, recently, since a large amount of ink is ejected and a large amount of ink is ejected in a short time due to an increase in printing speed, stable refilling is not performed and unstable ink ejection is performed, which deteriorates the printing quality. Was often seen to cause.

As means for solving such a problem, Japanese Patent Laid-Open No. 1-308644 proposes to provide a pressure-volume converter in the top plate 300. Moreover, FIG.
As shown in FIG. 0, a small chamber 310, which partially communicates with the common liquid chamber, is provided inside the common liquid chamber 302 of the top plate 300, and the small chamber (bubble cell) 310 and the common liquid chamber 302 have a plurality of portions. It is also proposed that the ink ejection ports 301 communicate with each other in the direction in which they are provided.

Since the small chamber 310 and the common liquid chamber 302 are communicated with each other by a minute communication portion, the small chamber 310 has a shape that makes it difficult for ink to enter. That is,
Air is always present in the small chamber 310. This air produces the same effect as the pressure-volume converter proposed in JP-A-1-308644, absorbs the pressure fluctuation at the time of ink ejection, and a stable refill can be obtained, thereby achieving good printing at high speed. Can be implemented.

In addition, at a corresponding position of the small chamber 310 on the heater board 200, when ink enters the small chamber 310 as proposed in Japanese Patent Application No. 6-176653, the small chamber 310 is placed inside the small chamber 310. A heater (not shown) for generating bubbles is provided.

The volume of the common liquid chamber 302 is made as small as possible in order to suppress the amount of waste ink at the time of recovery (described later) and to improve the efficiency of use of ink. For example, as shown in FIG. 9, the angle θ between the heater board 200 and the side surface of the common liquid chamber parallel to the plane of the orifice is formed to be about 10 deg.

[0012]

In the ink jet recording head, when air bubbles such as air exist in the ink from the common liquid chamber 302 to the ink ejection port 301, the air bubbles become nuclei and the air bubbles are formed over time. It is known to grow, interrupt the flow of ink, and cause non-ejection of ink. Therefore, the inkjet recording apparatus is generally provided with a recovery device or the like for periodically sucking the ink and removing the bubbles.

The air in the bubble cell 310 provided in the liquid chamber is no exception, and the air bubbles may serve as nuclei to grow and reach the ink path to cause non-ejection of ink. Therefore, the bubble cell 310 is arranged at a position as far as possible from the ink ejection port 301.

However, recently, the size of the heater board has been reduced in order to reduce the size of the ink jet recording head and the cost of the heater board, and the bubble cell 310 must be arranged near the ink ejection port 301. However, the bubbles growing from the bubble cell 310 may reach the vicinity of the ink ejection port in a period shorter than the interval at which the recovery device operates, and ink may not be ejected. In addition, since the volume of the common liquid chamber 302 has become smaller along with the miniaturization of the heater board, a small amount of air bubbles accumulated in the common liquid chamber 302 reach the vicinity of the ink path and cause non-ejection of ink. was there. The present invention has been made in view of the above problems, and it is an object of the present invention to provide an inkjet head that is smaller, less expensive, and has high reliability without causing non-ejection of ink.

[0015]

In order to achieve the above object, the ink jet recording head of the present invention forms a plurality of ejection ports and an ink path provided corresponding to each of the ejection ports. A top plate integrally having a plurality of grooves and a recess forming a common liquid chamber for storing ink supplied to the ink passage, and corresponding to the ink passage by being joined to the top plate In an ink jet recording head having an element substrate on which ejection energy generating elements are arranged, the top plate communicates with a common liquid chamber via a communication section and integrally has a small chamber in which gas is arranged. The direction of the surface of the communicating portion is formed so as not to intersect the row of the ink passages. In other ink jet recording heads, the angle between the element substrate and the common liquid chamber is greater than 40 deg.

With the above structure, the growth direction of the grown bubble is regulated, the grown bubble is less likely to be drawn into the ink passage 308, the non-ejection of ink is prevented, and the ink jet recording head and the heater board are further miniaturized. It is possible to provide a more reliable inkjet recording head.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In the following embodiments, the ejection energy generating element is described by using an electrothermal converter that generates heat energy, but an electrothermal converter such as a piezoelectric element may be used.

(Embodiment 1) FIGS. 1 to 3 show a first embodiment of an ink jet head to which the present invention is applied. FIG. 1 is a schematic perspective view schematically showing a part of an inkjet head to which the present invention is applied. 2 is an exploded perspective view of FIG. 1, and FIG. 3 is a perspective view of the top plate 300 seen from the common liquid chamber 302 side (the direction in which the inner surface is visible). Reference numeral 100 is a base plate that serves as a support member for forming each component. Ink passages (flow paths) provided corresponding to each of the plurality of ink ejection ports 301 in an element substrate (hereinafter referred to as a heater board) 200 on which a plurality of electrothermal converters (heaters) 201 as ejection energy generating elements are formed. ) Grooves forming 308, the ink ejection openings 301, a concave portion forming a common liquid chamber 302 for storing ink supplied to the ink passages, and a cylindrical ink supply for supplying ink to the common liquid chamber 302 The top plate 300 integrally provided with the opening 305 is provided with the plurality of heaters 201 and the plurality of ink ejection openings 301.
Are joined at corresponding positions. At the time of this joining, the top plate 300 is temporarily fixed to the heater board 200 with an adhesive, and a mechanical pressure is applied from the top of the top plate 300 by a spring (not shown) for giving a biasing force to obtain a sufficient close contact state. ing. At this time, by providing the convex portion 306 behind the common liquid chamber 302 of the top plate 300, the contact portion between the heater board 200 and the top plate 300 has a plurality of inks forming the convex portion 306 and a plurality of ink paths 308. Since it becomes the road wall 307, the ink road wall 307 and the heater board 200 are more closely adhered to each other, and more stable ink ejection is performed. After that, the top plate 300 and the heater board 20
The periphery of 0 is sealed with a sealant (not shown), and the sealant flows into a small gap between the heater board 200 and the common liquid chamber wall 303, and the plurality of ink paths 308 and the common liquid chamber 30.
2 is sealed from the outside. In this embodiment, this gap, that is, the step between the convex portion 306 and the common liquid chamber wall 303 is 5
˜20 μm. In the common liquid chamber 302 of the top plate 300, a bubble cell 310 is integrally provided on the top plate in order to absorb the pressure fluctuation at the time of ink ejection and obtain a stable refill as described above. As shown in FIG. 3, the bubble cell 310 is arranged at a position as far as possible from the plurality of ink ejection ports 301, and the bubble cell 310 and the common liquid chamber 302 are communicated with each other by a minute communication portion 311. In the present invention, the direction of the surface of the minute communication portion (direction perpendicular to this surface) does not intersect the row of the ink paths 308. For this reason, it is possible to prevent bubbles that have grown with the bubbles in the bubble cell 310 as nuclei from being directly in the vicinity of the ink path 308, and to prevent a non-ejection of ink, and to reduce the size, cost and reliability of the inkjet. The recording head could be obtained. In particular, in this embodiment, since the direction of the surface of the minute communication portion is substantially parallel to the direction of the row of the ink passages 308, even if the bubbles grow, the bubbles only grow in the direction of the row of the ink passages 308. The bubbles are suppressed from reaching the ink path.

(Embodiment 2) FIG. 4 is a schematic cross-sectional view showing the internal structure of the ink jet recording head on the XX plane of FIG. 1 when the top plate 300 to which the second embodiment is applied is mounted. . Since the configuration other than the top plate 300 is the same as that of the first embodiment, detailed description thereof is omitted here.

As the ink jet recording head and the heater board are downsized, the volume of the common liquid chamber 302 of the top plate 300 is also reduced. For this reason, even the small air bubbles that have accumulated in the common liquid chamber 302, which is not a problem in the past, may interrupt the flow of ink and cause non-ejection of ink. In particular, the bubbles accumulated in the common liquid chamber 302 are
It was found that the ink was easily pulled by both ends of the ink ejection port where the ink flow velocity was high, and the ejection failure of the ink occurred at both ends of the ink ejection port. Therefore, as shown in FIG. 4, the angle θ formed by the heater board 200 and the side of the common liquid chamber parallel to the orifice plane is 35 deg, 40 deg, 4
Three types of 5 deg were prototyped, and a continuous print test of an A4 size standard document was conducted to examine the number of prints until bubble discharge occurred. Table 1 shows the results.

[0022]

[Table 1]

The number of printed sheets in the above-mentioned test of the conventional ink jet recording head is about 250 to 300. As shown in Table 1, the heater board 2 according to the present invention
00 and the side of the common liquid chamber parallel to the plane of the orifice are made larger than 40 deg, and the ceiling of the common liquid chamber is sufficiently higher than the ink ejection port, that is, both ends of the ink ejection port in the common liquid chamber. By reducing the flow velocity of the ink in some parts, bubbles are less likely to reach the vicinity of the ink path 308, and ink is not ejected up to a number equal to or more than that in the conventional ink jet recording head. An ink jet recording head could be obtained.

FIG. 5 is a perspective view of a top plate 300 of an ink jet head to which another embodiment of the present invention is applied, viewed from the common liquid chamber 302 side.

As shown in FIG. 5, the bubble cell 310 is used.
Is an example in which is arranged in the vicinity of the plurality of ink ejection ports 301. By providing the bubble cell 310 at such a position, as the heater board 200 becomes smaller, the distance from the end of the heater board to the outermost ink ejection port also becomes shorter. Although it is unavoidable to provide it in the vicinity, in this embodiment, the direction of the surface of the communicating portion 311 between the bubble cell 310 and the common liquid chamber (direction perpendicular to the surface) does not intersect the row of ink paths. . Particularly, in this embodiment, the direction of the surface of the communication portion 311 is configured to be the opposite direction to the side on which the ink path is arranged. Therefore, even if the bubble grows, it grows only in the direction opposite to the ink path, so that the bubble does not reach the portion of the ink path.

Further, by arranging the bubble cell at the position along the wall of the common liquid chamber in this manner, the bubble cell also functions as a sealant reservoir for blocking and sealing the common liquid chamber 302 from the outside, There is also an advantage that a highly reliable inkjet recording head can be provided without the sealant flowing into the ink passage 308.

The bubble cell 310 of the present invention includes a communication part 311.
Of the partition wall 312 for partitioning the bubble cell 310 and the common liquid chamber 302, the angle of the wall on the common liquid chamber 302 side is 40 deg with respect to the element substrate. It has a larger angle. As shown in FIG. 4, when the bubble cells 310 are arranged in the vicinity of the plurality of ink ejection ports 301, the partition wall 312 is arranged from the ink path wall 309 to the heater board 2.
It is desirable to form a slight recess on the side opposite to 00.
That is, when the top plate 300 and the heater board 200 are in close contact with each other, the heater board 200 and the partition wall 31 are
It is formed so that there is a slight gap between the two.
In this embodiment, this gap is 0.05 to 0.1 m.
m. This is to ensure the adhesion between the heater board 200 and the ink path wall 309 as described above.
With the above-described configuration, the bubbles grown with the bubbles in the bubble cell 310 as the nucleus are projected from the minute communication portion 311 to the common liquid chamber 302, and the bubbles are also projected from the gap to reach the ink path 308. In some cases, non-ejection of ink may occur. Therefore, the angle θ between the heater board 200 and the side surface of the common liquid chamber 302 of the partition wall 312, which is the present invention, is set to an angle larger than 40 deg, and the ceiling of the common liquid chamber 320 is sufficiently larger than the ink passage 308. It is necessary to form it high. As a result, the bubbles protruding from the gap are less likely to reach the vicinity of the ink path 308 as described above, and ink ejection failure does not occur, and a smaller, low-cost and highly reliable inkjet recording head is obtained. I was able to.

FIG. 6 is a schematic view of an ink jet recording apparatus IJRA to which the present invention is applied. The lead screw 5005 has a helix line which rotates via driving force transmission gears 5011 and 5009 in association with forward and reverse rotations of a driving motor 5013. Groove 50
The carriage HC engaging with 04 is a pin (not shown)
And is reciprocated in the directions of arrows a and b. A paper pressing plate 5002 presses the paper against the platen 5000 in the carriage movement direction. 5007, 5008
Is a home position detecting means for confirming the existence of the carriage lever 5006 in this area by a photo coupler and switching the rotation direction of the motor 5013. 5016
Is a cap member 502 that caps the front surface of the recording head.
Reference numeral 5015 is a member for supporting the inside of the cap, and 5015 is a suction means for sucking the inside of the cap to perform suction recovery of the recording head through the in-cap opening 5023. Reference numeral 5017 is a cleaning blade, and 5019 is a member that allows this blade to move in the front-rear direction, and these are supported by a main body support plate 5018. Needless to say, a well-known cleaning blade can be applied to this example instead of this form. Reference numeral 5012 denotes a lever for starting suction for suction recovery, which moves in accordance with movement of the cam 5020 that engages with the carriage, and the driving force from the driving motor is controlled by known transmission means such as clutch switching. To be done.

The capping, cleaning, and suction recovery are configured so that desired processing can be performed at their corresponding positions by the action of the lead screw 5005 when the carriage comes to the home position side area. Any of these can be applied to this example as long as the desired operation is performed. Each of the above-described configurations is an excellent invention, either alone or in combination, and shows a preferred configuration example for the present invention.

The apparatus has drive signal supply means for driving the ink ejection pressure generating element.

[0031]

As described above, according to the present invention,
The bubble cell provided inside the common liquid chamber of the top plate and the common liquid chamber communicate with each other in the direction of the surface of the communicating portion that is different from the direction of the ink path row. As a result, it becomes difficult for bubbles grown with the bubbles in the bubble cells as cores to reach the vicinity of the ink path, and it is possible to provide a highly reliable inkjet recording head that is smaller, less expensive, and does not cause non-ejection of ink. I can do it now.

Further, the angle formed by the heater board and the side surface of the common liquid chamber parallel to the plane of the orifice is set to 40 deg or more, and the ceiling of the common liquid chamber is set sufficiently higher than the ink passage, so that the inside of the common liquid chamber is Bubbles are less likely to reach the vicinity of the ink path, and ink ejection failure does not occur, and it is possible to provide a smaller, low-cost, highly reliable inkjet recording head.

[Brief description of drawings]

FIG. 1 is a schematic perspective view schematically showing a part of an inkjet head to which a first embodiment of the present invention is applied.

FIG. 2 is an exploded perspective view of FIG.

FIG. 3 is a perspective view of the top plate of FIG. 1 viewed from the common liquid chamber side.

FIG. 4 is a cross-sectional view taken along line XX of FIG. 1 when a top plate to which the second embodiment of the present invention is applied is mounted.

FIG. 5 is a perspective view of a top plate of an inkjet head to which another embodiment of the present invention is applied, viewed from the common liquid chamber side.

FIG. 6 is a diagram showing an inkjet device equipped with an inkjet head of the present invention.

FIG. 7 is a schematic perspective view schematically showing a part of an inkjet head of the background art.

FIG. 8 is an exploded perspective view of FIG.

9 is a sectional view taken along line XX of FIG.

10 is a perspective view of the top plate of FIG. 7 viewed from the common liquid chamber side.

[Explanation of symbols]

 100 Base plate 200 Heater board 201 Heater 300 Top plate 301 Ink ejection port 302 Common liquid chamber 303 Common liquid chamber wall 304 Orifice plate 305 Ink supply port 306 Convex portion 307 Ink passage wall 308 Ink passage 310 Small chamber 311 Micro communication portion 312 Partition wall 313 Ceiling of common liquid chamber 400 Sealant

Claims (10)

[Claims] 1. A plurality of ejection openings, and a plurality of grooves for forming ink paths provided corresponding to the respective ejection openings,
A top plate integrally having a recess forming a common liquid chamber for storing the ink supplied to the ink passage, and ejection energy arranged corresponding to the ink passage by being joined to the top plate In an ink jet recording head having an element substrate on which a generating element is arranged, the top plate integrally has a small chamber in which a gas communicating with the common liquid chamber through a communication portion is arranged, and the surface of the communication portion is Direction
An ink jet recording head, characterized in that it is formed so as not to intersect the row of ink paths. 2. The ink jet recording head, wherein the small chamber is provided at a corner of the common liquid chamber. 3. The ink jet recording head according to claim 1, wherein the ink jet recording head has a plurality of the small chambers. 4. The ink jet recording head according to claim 1, wherein the direction of the surface of the communicating portion is a direction along a row of ink paths. 5. The ink jet recording head according to claim 1, wherein the direction of the surface of the communication portion is opposite to the position where the ink path is arranged. 6. A plurality of ejection openings, and a plurality of grooves for forming ink paths provided corresponding to the respective ejection openings,
A top plate integrally having a recess for forming a common liquid chamber for storing the ink supplied to the ink passage, and a top plate joined to the top plate to be arranged corresponding to the ink passage. An ink jet recording head having an element substrate on which ejection energy generating elements are arranged, wherein an angle between the element substrate and a side surface of the common liquid chamber is larger than 40 deg. 7. A small chamber communicating with the common liquid chamber via a communicating portion inside the common liquid chamber of the top plate is provided in the vicinity of the common liquid chamber side of the ink passage. Inkjet recording head. 8. The ink jet recording head according to any one of claims 1 to 5, wherein the ink ejection energy generating element is an electrothermal converter that generates heat energy to act on the ink. Recording head. 9. An ink jet recording apparatus comprising: the ink jet recording head according to claim 1; and a drive signal supply unit for driving the head. 10. The ink jet recording apparatus according to claim 7, further comprising a tank for storing ink to be supplied to the ink jet recording head, wherein the tank and the ink jet recording head are detachably integrated. Characteristic inkjet recording device.