JPH06226975A - Ink jet head - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide an inkjet head used in an inkjet printer, which enables high-resolution and small-sized inkjet heads to be mass-produced at low cost. An ink jet in which 2n nozzle rows (n is an integer of 2 or more) are formed by vertically arranging a plurality of nozzles 12 and each nozzle 12 directly communicates with at least a part of a pressure chamber 13 In the head, when the nozzle that prints the highest dot is first and the nozzles that print the lowest dot are numbered in this order, the nozzle row to which the arbitrary mth nozzle belongs and the (m + n) th nozzle The nozzle row to which the nozzle belongs and the nozzle 12 are arranged close to each other, and the nozzle row to which the m-th nozzle belongs and the (m +)-th nozzle row.
The nozzle row to which the 1) -th nozzle belongs is arranged separately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet head used in an inkjet printer.

Inkjet printers are efficient and
It is characterized by its small size, high resolution, and quiet printing, and its popularity in recent years has been remarkable. However, recently, since there is a great demand for small printers represented by portable printers, further miniaturization, There is an urgent need to improve efficiency.

In order to meet these demands, the ink jet head is not only a so-called edge chute type in which a nozzle is provided on the end face of a thin plate-shaped head, but also a so-called side chute type in which a nozzle is provided on the plane of a thin plate. Among them, among them, in particular, the one in which a pressure generating source is provided almost directly below the nozzle to achieve downsizing and high efficiency (hereinafter referred to as a direct type) has begun to be developed.

[0004]

2. Description of the Related Art Examples of conventional direct type ink jet heads of this type are shown in FIGS. 22 (A) to 22 (D). These configurations are as follows. FIG. 22 (A) uses a piezoelectric element as a pressure generating source, and pressure chambers 1 as pressure generating portions are arranged in a substantially arc shape by connecting the nozzles 2 on both sides of the nozzles 2 in two rows. The piezoelectric element 3 facing each pressure chamber 1 is provided on the vibration plate in contact with each pressure chamber 1.
Are attached respectively. Nozzle 2 in the direction of arrow A
The ink jetting direction from the arrow head, and the arrow B direction is the head scanning direction.

FIG. 22 (B) shows that pressure chambers that are diagonally arranged to intersect with the scanning direction and communicate with respective nozzles are arranged in parallel. The piezoelectric elements 3 are attached respectively. FIG. 22
(C) shows that the nozzles are diagonally arranged in two rows and the pressure chambers are arranged in two rows facing each other.

Further, FIG. 22 (D) shows a bubble jet system using an electrothermal converting element 4 as a pressure generating source, and the electrothermal converting element 4 is provided in a pressure chamber 6 which is located just below a nozzle 5. It is located on the bottom.

[0007]

However, the above conventional structure has the following drawbacks. That is, in the case of FIG. 22 (A), since the useless space that does not contribute to the performance of the head becomes wider toward the outside of the nozzle, the head becomes relatively large and the shape of the pressure chamber becomes complicated. It is necessary to devise a medium feeding mechanism to solve the problem peculiar to an ink jet printer in which the medium becomes dirty when the medium is pressed immediately after printing.

Further, in the case of FIG. 22B, if the number of nozzles is increased in order to increase the resolution, the lateral width of the head becomes large, and there is a risk of contact with the medium at the time of scanning the head and soiling or breaking the medium. As the number of nozzles increases, the drive timing control must be performed for each nozzle, which complicates the control method and makes it difficult to maintain print quality.

Further, in the case of FIG. 22 (C), two pressure chambers are provided.
Although the above-mentioned drawbacks are attempted to be improved by aligning them in rows, the drawback that the control method becomes complicated and it becomes difficult to maintain the print quality remains.

Further, in the case of FIG. 22D, since the energy density of the drive source is high, it is possible to use a relatively small pressure chamber, which is considerably smaller than those of FIGS. 22A to 22C. Head can be realized with few drawbacks. However, with this shape as it is, the resolution is limited to about 300 dpi, and it is difficult to achieve higher resolution.

It is an object of the present invention to provide an ink jet head which makes it possible to produce a high resolution small ink jet head at a low cost.

[0012]

In order to achieve the above object, according to the present invention, an ink jet head having 2n nozzle rows (at least an integer of n ≧ 2) formed of at least one nozzle is formed. When the nozzles that print the upper dots are the first nozzles and the nozzles that print the lowest dots are numbered in this order, the nozzle row to which the arbitrary mth nozzle belongs and the (m + n) th nozzle Is arranged in close proximity to the nozzle row to which
The nozzle array to which the m-th nozzle belongs and the nozzle array to which the (m + 1) -th nozzle belongs are arranged apart from each other (first configuration).

In addition, in the ink jet head of the above-mentioned first structure, the ink supply path is such that the two pressure chamber rows corresponding to the two nozzle rows that are arranged close to each other with the nozzles facing each other are one pressure chamber group. The entire circumference is surrounded by the structure (second structure).

In the ink jet head having the second structure, there are a plurality of pressure chamber groups, and the ink supply passages surrounding them are separated for each pressure chamber group, and the separated ink supply passages have different colors. The third configuration is characterized in that the above ink is supplied.

Further, in the edge shoot type or side shoot type ink jet head, the pressure chamber width is kept constant and connected to the ink supply path (fourth constitution).

Further, in the ink jet head having the above-mentioned fourth structure, an isolated partition is provided in the vicinity of the inlet portion of each pressure chamber of each pressure chamber row that sandwiches the ink supply path and is opposed ( The fifth configuration).

[0017]

In the case of the first structure, the pressure chambers can be arranged reasonably without taking an unnecessary area. Further, since the nozzle rows are close to each other by two rows, it becomes possible to treat the two nozzle rows as a pseudo one row when performing head drive control, that is, the control becomes very easy. .

In the case of the second configuration, by forming the ink supply path in such a shape, ink can be supplied to each pressure chamber from either the upper side or the lower side, and the substantial ink supply capacity is increased. As a result, ink ejection becomes more stable and high-speed printing becomes possible.

In the case of the third configuration, since the inks of different colors are supplied to the respective separated ink supply paths to enable printing of a plurality of colors, the color can be printed by minute line breaks by the number of colors. Printing can be performed.

In the case of the fourth configuration, since the pressure chamber is connected to the ink supply passage with the width kept constant, the head size is smaller than that in the case where the pressure chamber and the ink supply passage are connected by narrowing the flow passage. Get smaller.

In the case of the fifth configuration, when one of the pressure chambers facing each other is driven, it is possible to prevent the pressure from propagating to the other pressure chamber and eliminate a malfunction.

In summary, according to the present invention, it is possible to obtain a high-resolution and small-sized ink jet head at low cost.

[0023]

Embodiments of the present invention will be described below with reference to FIGS.

The present invention realizes a structure in which the pressure chambers are reasonably arranged in a minimum area and the drawbacks of the conventional example can be minimized. Therefore, the pressure chambers must be divided in the vertical direction, including the partition wall, so that the maximum width is 2n times the resolution pitch of the head (where 2n is the number of nozzle rows described above). The scanning direction of the inkjet head is determined to have the minimum necessary width according to the performance of the driving source. Next, each example will be described in detail.

1 to 4 show a first embodiment.

FIG. 1 is a structural explanatory view of the ink jet head of this embodiment, and FIG. 1A shows a standard arrangement of each pressure chamber and nozzle. In the ink jet head 11 of FIG. 1A, a plurality of nozzles 12 are arranged in a row in the vertical direction to form 2n nozzle rows (where n ≧ 2), and each nozzle 12 is connected to a pressure chamber 13. is doing. It should be noted that this figure shows the case where n = 2.

In each nozzle row, the nozzle that prints the highest dot (the top nozzle of the leftmost nozzle row) is the first nozzle, and the nozzle that prints the lowest dot in the following order (first nozzle) When numbers are added up to the bottom nozzle of the right nozzle row (in the figure, the number in parentheses <> attached to the pressure chamber 13 is the nozzle number), and any <m> th nozzle The nozzle row to which the nozzle row belongs and the nozzle row to which the (m + n) th nozzle belong are arranged in proximity to each other, and the row to which the mth nozzle belongs and the nozzle row to which the (m + 1) th nozzle belong belong to each other. Has been done.

Explaining these arrangements concretely, for example, the nozzle row to which the ninth nozzle 12 belongs (the leftmost row) and the nozzle row to which the 11th nozzle 12 (9 + 2) belongs (from the left The second row) is close to the nozzle row to which the ninth nozzle 12 belongs and the nozzle row (third row from the left) to which the tenth nozzle 12 of (9 + 1) belongs is separated.

When the nozzles and the pressure chambers are arranged as described above, the pressure chambers can be arranged reasonably without taking an unnecessary area. Further, although the number of nozzle rows is four, since two rows are close to each other via the interval a, it is possible to treat them as two rows when performing head drive control. This is much easier to control as compared to the case where four-column control is performed.

Incidentally, when the distance a in FIG. 1A (for example, the inter-row distance between the nozzle row having the 9th nozzle and the nozzle row having the 9 + 2nd nozzle) is added, for example, the resolution is 360 dpi. In this case, the dot pitch p is 70.
5 μm (= 360 / 25.4 × 1000 μm),
If a is set to an integral multiple of p, the print timings of the two nozzle rows can be synchronized. Therefore, the number of timing signals is only one, and the control is easy.

However, in general, in a serial dot printer, in order to make the connection of diagonal lines beautiful, dots are printed at a position corresponding to twice the apparent resolution in the horizontal direction. If this is also taken into consideration, it suffices to set a to an integral multiple of p / 2.

Further, regarding the dimension b in FIG. 1A (for example, the distance between the nozzle row having the 9th nozzle and the nozzle row having the (9 + 1) th nozzle), the contents and effects are as described above. It is almost the same.

The ink jet head 21 shown in FIG. 1B has a nozzle 22 and a distance between nozzle rows shown in FIG.
Is set so as to have a constant ratio with the vertical interval (depending on resolution) of the pressure chambers, and the upper and lower partition walls of the pressure chambers 23 corresponding to each nozzle row have 2n horizontal pressure chambers. A straight line is formed across the row as indicated by the dotted line. Therefore, each pressure chamber 23 has a shape as illustrated.

In this case, the area of the pressure chamber may be smaller than that in the case of FIG. 1 (A) depending on how the partition wall is determined, but the dimensional inspection is facilitated and, as will be described later, it serves as a drive source. When a piezoelectric element or the like is used, it is possible to adopt a method in which the drive source is integrally formed and then separated, and the manufacturability is significantly improved.

Further, in the ink jet head 31 of FIG. 1 (C), in order to maximize the area of the pressure chamber of FIG. 1 (B), the straight lines formed by the upper and lower partition walls are parallel to each other, and the shape of the pressure chamber is parallel four sides. It is a shape. In the figure, 32 is a nozzle and 33 is a pressure chamber.

In this case, since the width of the partition wall is constant everywhere, the area of the portion that does not contribute to ink ejection is eliminated, and as a result, the head can be made smaller than that in FIG. 1B.

FIG. 2 is a structural explanatory view of the ink supply path of the ink jet head 11 of FIG. 1A. As shown in FIG. 2A, each pressure chamber 13 in the first row from the left is an ink supply path. 41a, and each pressure chamber 13 in the second and third rows
Is connected to the ink supply passage 41b passing between the two rows, and each pressure chamber 13 in the fourth row is connected to the ink supply passage 41c.

By the way, the frictional resistance of the pipeline is
As is known as the Weisbach equation, it is inversely proportional to the fourth power of the cross-sectional area. Therefore, as compared with the conventional method as shown in FIG. 2B, the width of the ink supply path in the horizontal direction required can be reduced by making the ink supply path common. This is also an effective means for downsizing the head.

Another example of the ink supply path is shown in FIG. In a serial dot printer, it is rare that all nozzles are driven at the same time, except for the case of full solid printing. Therefore, the ink supply path 42 has a shape as shown in FIG. 3A (the ink supply path is formed so that two pressure chamber rows corresponding to two nozzle rows in which nozzles are close to each other form one pressure chamber group). Since the entire circumference is surrounded by 42, ink can be supplied to each pressure chamber 13 from both the upper and lower sides of the common ink supply path 42, and the substantial ink supply capacity is increased. This stabilizes the ink ejection and enables high-speed printing.

FIG. 3B shows an ink supply passage 43 for yellow which connects the ink supply passage to each pressure chamber row.
a, a cyan ink supply path 43b, a magenta ink supply path 43c, and a black ink supply path 43d.
Shows the separated one. This head can print four colors in one pass and can print characters by four minute line breaks. Of course, it is also possible to print black with a mixture of three colors. In that case, the pressure chamber group may be separated into three rows. By doing so, a small and single color head can be realized.

When ink is supplied from the ink supply path to each pressure chamber as described above, it is important to properly set the positions of the ink supply path and the nozzles in order to eliminate the retention of bubbles.
FIG. 4 shows how to set these positions. Figure 4 below
This will be described in detail with reference to (A) to FIG.

As shown in FIG. 4B, when the nozzle 51 is not located at the corner of the pressure chamber 52, bubbles 54 are likely to remain in the pressure chamber 52 during the initial ink injection from the ink supply passage 53. Even when the air bubbles are sucked from the nozzle 51 at that timing, the air bubbles 54 are easily caught at the same position. Even if the ink discharge operation is performed, the bubbles are not easily discharged because they are at the stagnation point of the ink flow.

If air bubbles are present inside the pressure chamber, the pressure wave generated by the driving source is greatly attenuated, and the ink ejection is stopped. On the other hand, when the nozzle 51 is arranged in the vicinity of the corner of the pressure chamber 52 as shown in FIG. 4 (A), even if bubbles are present, the ink flow indicated by the arrow at the time of the discharging operation is changed. Since it rides, it can be easily ejected and the reliability of the head is improved.

Even if the nozzles are provided at the corners of the ink chamber as described above, if the ink supply passage 53 is connected to the center of the pressure chamber 52, as shown in FIG. Bubbles tend to remain in the right corner of the pressure chamber 52. This place is also a stagnation point of the ink flow at the time of the ink discharging operation, and bubbles are not easily discharged. Therefore, when the ink supply path 53 is diagonally arranged with respect to the nozzle 51 as shown in FIG. 4D, the flow of ink is as shown by an arrow line in the figure, and there is no stagnation point, and bubbles remain when ink is injected. However, the reliability of the head is further improved.

Further, as shown in FIG.
When the structure of (D) is arranged point-symmetrically, the individual pressure chambers 52 can have exactly the same shape from the ink supply passage 53 to the nozzle 51. This facilitates ensuring the head characteristics.

A second embodiment is shown in FIGS.

In the structure of the previous example, the pressure chamber and the ink supply passage are connected by narrowing the passage. As a result, the distance from the tip of the pressure chamber to the ink supply path becomes long, and the head size becomes large. For example, when forming a nozzle plate, flow path plate, etc. by etching, the size of the original plate used for etching is constant, so if the size of one part increases, the number of parts obtained from one plate decreases. It leads to cost increase. Therefore, it is necessary to reduce the size of each component as much as possible.

This example solves this problem by proposing a flow path structure with a short distance between the pressure chamber and the ink supply path, increasing the number of flow path plates obtained from one plate, and reducing the head cost. It is intended to go down. Further, as a shape that replaces the conventional diaphragm, an isolated partition is provided in the ink supply passage at the inlet of the pressure chamber in order to suppress crosstalk that occurs between the pressure chambers through the ink passage. The shape of the head of this example is shown in FIGS. 7 and 8. In the figure, 61 is a nozzle, 62 is a pressure chamber, 63 is an ink supply path, and 64 is an isolated partition.

FIG. 5 is an explanatory view for comparing the flow path lengths.
FIG. 5A shows the case of this example, and FIG. 5B shows the conventional example. The width of each pressure chamber is 1 mm, and other dimensions are as illustrated. In FIG. 5B, since the pressure chambers 13 are provided on both sides of the middle ink supply path 42, the vibration of the piezoelectric element is propagated to the opposite pressure chambers and ink droplets are ejected from the nozzles corresponding to the pressure chambers. There is a risk of jetting.

Therefore, the pressure chamber 13-ink supply path 42
A passage is provided with a throttle to increase the propagation loss of pressure and suppress the influence on other pressure chambers. As a result,
As shown in (B), the distance from the pressure chamber tip to the ink supply path is 1.6 mm (= 0.05 + 0.1 + 0.8 +
0.45 + 0.2) is required. Also, 1.75 mm (1.6 + 0.15) is required to reach the center of the ink supply path.

Therefore, when four nozzles are arranged in the vertical direction and 16 nozzles are arranged in the horizontal direction as shown in FIG. 6, the partition wall width between the adjacent pressure chambers is 0.2 mm and the ink supply path width is 0.5 m.
When the length is m, the vertical dimension of the main part of the head is 5.3 mm. Considering the width, if the partition wall width of the flow path between the closest nozzles is 0.2 mm, the width of one row is 1.75 + 0.2 = 1.95 mm.

Therefore, when 16 rows are arranged, the lateral width of the main part of the head is 1.95 × 16 = 31.20 mm.

On the other hand, in the structure of this example, the lateral width can be greatly reduced. Next, the width will be described with reference to FIG.

In the case of this example, the pressure chamber 62 is directly connected to the ink supply passage 63 without narrowing its width. The pressure chamber length is 0.
The width is 8 mm and the width is fixed to 1 mm. Further, instead of the conventional diaphragm, an isolated partition 64 of 0.1 mm × 0.6 mm is provided in the ink supply path to narrow the flow path and to serve to attenuate the vibration of the piezoelectric element. Further, by making the width of the isolated partition 64 as narrow as 0.1 mm, the influence on the overall size of the head can be made extremely small.

From FIG. 5A, the distance from the tip of the pressure chamber 62 to the center of the ink supply passage 63 is 0.05 + 0.1 + 0.8 + 0.15 = 1.1 mm. Therefore, when 4 nozzles are arranged in the vertical direction and 16 nozzles are arranged in the horizontal direction as shown in FIG. 7, assuming that the partition wall width of the flow path between the closest nozzles is 0.2 mm, the width of one row is
It becomes 1.1 + 0.2 = 1.3 mm. When 16 columns are arranged, 1.3 × 16 = 20.8 mm.

Therefore, when this value is compared with the case of FIG. 5 (B), the width is reduced from 31.2 mm to 20.8 mm by about 2
It can be reduced to / 3.

Considering the operation of the piezoelectric element, the wider the pressure chamber, the easier the vibration. Therefore, in the structure of the previous example in which the throttle is provided at the rear of the pressure chamber, it is difficult to reduce the size of the piezoelectric element because there is a portion where the flow path width becomes narrow. According to experiments conducted by us, it has been clarified that when the size of the piezoelectric element (pressure chamber) is reduced, the driving voltage is high and the amount of ejected ink is reduced. On the other hand, when the diaphragm is not provided as in the present example, the vibration load on the piezoelectric element does not increase, so there is an advantage that the size of the piezoelectric element (pressure chamber) can be made smaller than in the previous example.

FIG. 8 shows a nozzle diagonal two-row array type head of this example. This head has a distance between adjacent nozzles of 0.5.
5, the nozzle pitch is 0.706 mm (1/3
In order to obtain 60 inches), it is necessary to tilt it by 7.37 ° and mount it on the carriage.

The main constitution and effect of the ink jet head of the present invention have been described with reference to the first and second embodiments described above. Next, the operation and manufacturing method of these heads will be described.

9A and 9B are explanatory views of the operation of the ink jet head using a piezoelectric element as a drive source. FIG. 9A shows the non-operating state and FIG. 9B shows the operating state. In the figure, 71 is a nozzle plate provided with a nozzle 71a, 72 is a flow path plate having a pressure chamber 72a and an ink supply path (not shown) communicating with the pressure chamber 72a, and 73 is a vibrating plate. Are laminated by adhesion or the like. 74 is a piezoelectric element. The pressure chamber 72a communicates with the nozzle 71a, and the piezoelectric element 74 is fixed to the surface of the vibration plate 73 by adhesion or the like and faces the pressure chamber 72a.

FIG. 9A shows a state in which no voltage is applied to the piezoelectric element 74, and the vibration plate 73 is not deflected. FIG. 9B shows a state in which a voltage is applied to the piezoelectric element 74,
The vibrating plate 73 is bent by the displacement force of the piezoelectric element 74, and the ink particles 75 are ejected from the nozzle 71a.

FIG. 10 is a diagram for explaining the operation of the ink jet head utilizing electrostatic force, and FIG. 10 (A) shows the non-operation state.
0 (B) indicates the time of operation. In the figure, 81 is the nozzle 8.
1a is a nozzle plate, 82 is a flow path plate having a pressure chamber 82a and an ink supply path (not shown), 83 is a vibrating plate, 84
Is an insulating layer having an air gap 84a, and 85 is a substrate.

FIG. 10A shows a state in which no voltage is applied, and the diaphragm 83 is not deflected. FIG. 10B shows a state in which a voltage is applied as shown in the drawing. The vibrating plate 83 is bent by the electrostatic force, and the ink particles 86 are ejected by the nozzle 81a.
Is jetted from.

FIG. 11 is a diagram for explaining the operation of the ink jet head using the electrothermal converting element. FIG. 11 (A) shows the non-operating state and FIG. 11 (B) shows the operating state. In the figure, 91 is a nozzle plate provided with a nozzle 91a, 92 is a flow path plate provided with a pressure chamber 92a and an ink supply path (not shown), 93 is a substrate, and 94 is an electric device arranged on the substrate 93 in the pressure chamber 92a. It is a heat conversion element.

FIG. 11A shows a state where the electrothermal converting element 94 is not energized. FIG. 11B shows a state in which the electrothermal converting element 94 is energized, and a portion of the ink is instantly boiled by the generated heat energy to form a bubble 96.
Ink particles 95 are ejected from the nozzles 91a by the growth of the bubbles.

FIG. 12 is an explanatory diagram of a piezoelectric element forming method.
Normally, the piezoelectric element is bonded on the vibrating plate at a position corresponding to each pressure chamber as described above (FIG. 9), but in the case of FIG. 12, the piezoelectric element having a size that covers a plurality of pressure chambers. After joining 101, this is cut at a position just above a partition wall that divides the pressure chambers to form pressure chambers corresponding to the respective pressure chambers.

As a cutting machine, it is effective to use a precision slicer used for cutting semiconductors and the like. In this case, the width of the cutting groove can be made extremely thin, about 50 μm, so that the removed portion can be prevented from becoming unnecessarily large and the head can be prevented from becoming unnecessarily large, and the cutting position accuracy can be kept within an error of about ± 5 μm. The variation in size of individual piezoelectric elements can be made very small.

FIG. 13 is an explanatory view of another method for forming a piezoelectric element, in which the piezoelectric element 100 is larger than that covering all the pressure chambers.
After joining, cut it by the same method as in FIG.
A pressure chamber corresponding to each pressure chamber is formed. As a result, an unnecessary portion (hatched portion in the figure) remains on the outer periphery of the piezoelectric element group. Generally, when bonding a piezoelectric element to a diaphragm,
Depending on the amount of adhesive applied, the adhesive may stick out to the surface of the element and harden.

If this protruding adhesive covers the electrodes on the surface of the element, it will cause poor conduction. This problem,
This can be solved by providing an unnecessary portion on the outer circumference of the piezoelectric element group as shown in FIG. Further, when the piezoelectric element is soldered to the vibration plate, the element itself is generally thin, so the solder becomes a bridge between the upper and lower electrodes on the outer periphery of the piezoelectric element,
May cause insulation failure. If the insulation is severely defective, the device itself may be destroyed, which is a big problem.

Even in such a case, if an unnecessary portion is provided on the outer periphery of the element, even if a solder bridge occurs, insulation is secured in the portion to be actually used, which causes a problem in use. There is no such thing. Further, when the piezoelectric element is cut, chipping (a minute chip) is likely to occur at the start and end of cutting, but if an unnecessary portion is provided on the outer circumference, even if chipping occurs, it is actually used. Since there is no damage on the part, it will not be a defective product. Therefore, the yield of the head is improved and the reliability is also improved.

FIG. 14 is an explanatory view of a means for aligning the piezoelectric element and the pressure chamber. Reference numerals 103 ₁ and 103 ₂ are cross-shaped reference marks provided outside the bonding range on the bonding surface of the piezoelectric element 101. When cutting the piezoelectric element after adhering it to the vibration plate, the positional deviation between the cutting position and the pressure chamber becomes a serious problem.
If the displacement becomes large, the displacement of the piezoelectric element cannot be effectively transmitted to the vibration plate, and at the same time, when a piezoelectric element corresponding to a certain pressure chamber is driven, a part of the element is applied to another adjacent pressure chamber. Therefore, there is a problem that mechanical interference occurs.

Therefore, it is important how to reduce the displacement, but since the piezoelectric element is opaque, it is impossible to align the element with the pressure chamber through the element.
This problem can be solved accurately and easily by forming the reference mark 103 that serves as a reference for the cutting position of the pressure chamber at the same time when forming the flow path plate.

FIG. 15 is an assembly process diagram of the head. The head includes a nozzle plate 111 having nozzles 111a,
A flow path plate 112 (corresponding to an integrated flow path plate 72 and vibration plate 73 in FIG. 9) having a pressure chamber 112a and an ink supply path (not shown) communicating with the pressure chamber 112a, and a piezoelectric element. 113 is laminated and the assembling process is as follows.

First, the nozzle plate 11 shown in FIG.
1. Create the flow path plate 112. The nozzle plate 111 is manufactured by etching a photosensitive glass (product name: PEG3, manufactured by Hoya Corporation). The nozzle diameter was 50 μm and the plate thickness was 200 μm. The nozzle manufacturing method is not limited to this method, and an electroforming method or the like may be used.
The flow path plate 112 was manufactured by etching photosensitive glass. The plate thickness was 150 μm and the etching depth was 50 μm. Silicon or stainless steel may be used as the material, and the flow path may be formed by etching. Also,
It is also possible to form a flow path plate by subjecting one plate to unevenness by pressing.

Next, these two sheets are joined as shown in FIG. For joining, the parts must not fall out during use, and at the same time, they must be joined tightly and tightly at the very thin partition wall so that crosstalk with the adjacent pressure chamber does not occur. It is necessary to satisfy the following two points: that the adhesive and the binder do not overflow into the pressure chamber, block the nozzle, tend to accumulate bubbles, and hinder the ink flow.

Therefore, when various bonding experiments were conducted,
It was confirmed that the following three types of joining methods were effective.
That is, three methods are effective: a method using an epoxy adhesive, a method using an ultraviolet-curing anaerobic adhesive, and a brazing method. Next, each case will be described in detail.

When an epoxy adhesive is used, it is desirable to use a two-liquid mixing type having a relatively high viscosity, and its application is carried out by using a rubber roller or a bar coater, and a small amount of the adhesive is thinly and uniformly applied to the flow path plate. To do so. After that, it is combined with the nozzle plate and heated and cured while being pressurized. As the epoxy adhesive, AW106, HV953U manufactured by Ciba Geigy (cured at 80 ° C. for 3 hours) is used.

UV curable anaerobic adhesive (LI210,
When Loctite) is used, the coating method is the same as that of the epoxy adhesive, but when it is cured, it is different in that it is irradiated with ultraviolet rays while applying pressure. If either the nozzle plate or the flow path plate is transparent, the adhesive can be directly irradiated with ultraviolet rays, but even if both are opaque, the adhesive exposed at the ends is cured by ultraviolet rays and the internal adhesion The agent is shielded from the air and then gradually hardens to the inside due to anaerobicity.

The advantage of using the adhesive is that the material of the flow path plate and the nozzle plate can be selected quite freely, and the work can be performed at a relatively low temperature of 100 ° C. or less, so that dimensional deviation and warpage can be prevented. ， It is the point that the transformation of the material is hard to occur.

Further, in the case of brazing, it is necessary that both the flow path plate and the nozzle plate are made of metal. In the brazing procedure, solder plating, nickel plating, or the like is applied to the surface of the flow path plate as a binder, and while being strongly pressed together with the nozzle plate, heating is performed above the melting point of the binder agent to perform bonding. The characteristics of brazing are that the strength is very high, there is almost no leakage or overflow, and even if a strong solvent is mixed in the ink, the joint portion is not damaged.

Next, as shown in FIG. 15 (C), a silver paste (Silvest, PS707, manufactured by Tokuriki Kagaku Kenkyusho) is applied to the surface of the flow path plate 112 on which the flow path is not formed.
The electrode 114 is formed by baking at 0 ° C. for 1 hour. If a stainless steel plate is used as the flow path plate,
This electrode formation is unnecessary.

Next, as shown in FIG. 15D, the piezoelectric element 113 made of TOKIN is bonded onto the flow path plate 112. Regarding this joining, the displacement energy of the piezoelectric element is efficiently transmitted to the vibrating plate (the portion of the flow path plate 112 that is in contact with the pressure chamber 112a), and at the same time, the piezoelectric element is firmly joined to withstand repeated loads. The piezoelectric element does not operate unless electrical conduction is established between the lower electrode and the electrode 114, so that the bonding layer has conductivity or the bonding layer is very thin (about 10 μm or less). Must be in contact with the electrode 114.

Therefore, various bonding experiments were conducted, and it was confirmed that the following various bonding methods were effective. That is, a method using an epoxy adhesive, a method using an ultraviolet curable adhesive, a method using a conductive adhesive, and a soldering method are effective.

When an epoxy-based adhesive is used, the adhesive used and the application method are the same as those in the above case (joining of the nozzle plate and the flow path plate), so a detailed description thereof will be omitted. Is good. It should be noted that even better results can be obtained by performing defoaming treatment in a vacuum chamber after applying the adhesive.

When an ultraviolet curable anaerobic adhesive is used, bonding is performed in the same manner as in the above case, but since the work can be performed at a relatively low temperature of 100 ° C. or less, deterioration of the piezoelectric element is unlikely to occur.

On the other hand, in the case of soldering, the flow path plate needs to be made of metal. As for the soldering procedure, solder plating is applied to the surface of the flow path plate, and while being strongly pressed together with the piezoelectric element, heating is performed at a temperature equal to or higher than the melting point of the solder for joining.
The characteristics of soldering are that the strength is very high and there is no conduction failure due to the conductivity, and the bonding layer is very thin because the solder is plated on the diaphragm. Note that when soldering is performed, the piezoelectric element is exposed to high temperatures, so it is desirable to take repolarization measures for the element.

After that, as shown in FIG. 15E, after cutting with a dicing saw (DAD25P / 6T, DISCO Co., Ltd.), a joint 115 is attached to the supply port as shown in FIG. Connect to a cartridge (not shown). Then, as shown in FIG. 15G, the flexible cable 1 connected to the piezoelectric element drive source
16 is drawn up to immediately before the piezoelectric element, and connected to each piezoelectric element by wire bonding.

FIG. 16 (A) shows details of the connecting portion by the wire bonding. As is apparent from this figure, the exposed surface of the conductor 116a of the flexible cable 116 and the piezoelectric element are connected by wire bonding. 116b
And 116c are a base film and a cover film of the flexible cable 116. The features of this case are that the equipment is versatile and low in cost. However, since the piezoelectric element vibrates, it is necessary to reinforce the bonding strength (silicon coating or the like) that also has a moisture-proof effect.

Next, a connection method other than the above wire bonding will be described.

FIG. 16B shows a thermocompression bonding method in which the exposed conductor of the flexible cable 116 and the surface of the piezoelectric element 113 are surface-treated with solder 117 having a thickness of several μm to several tens of μm.
The heater 118 applies heat and pressure for soldering. Its features are low cost and high reliability of connection strength. However, in order to avoid short circuit between adjacent electrodes,
Careful control of pitch and solder surface treatment thickness is required.

16C and 16D show a bump bonder method. First, as shown in FIG. 16C, solder bumps (solder balls) 119 having an outer diameter of about several μm to several tens of μm are formed on the piezoelectric element 113. Is provided, and is thermally pressed by the heater 118 to perform soldering as shown in FIG. The feature of this method is that the possibility of short circuit between adjacent ones can be reduced as compared with the thermocompression bonding method.

FIG. 16 (E) shows an anisotropic conductive rubber system, which is shown in FIG.
As shown in FIG. 6 (E), the anisotropic conductive rubber 120 is inserted between the piezoelectric element 113 and the flexible cable 116,
The pressure is applied to this by the pressure plate 122 through the elastic member 121 provided with the convex portion 121a only on the exposed portion of the conductor, so that electrical continuity is achieved. The feature of this method is that the piezoelectric element does not need to be heated, and thus the repolarization process is unnecessary. However, it is necessary to properly set the hardness and pressure of the elastic material so as not to disturb the vibration of the piezoelectric element.

FIG. 16F shows an anisotropic conductive film system,
This is an improved version of the anisotropic conductive rubber system. in this case,
This is a system in which an anisotropic conductive film 123 is inserted between the piezoelectric element 113 and the flexible cable 116, and the exposed portion of the conductor is thermally pressed by a heater 118 to establish conduction. An anisotropic conductive film (trade name: Anisorum, etc.) is a mixture of thermosetting resin and conductive powder, and its characteristic is that the thermosetting resin cures after being heated and pressed, so that it is similar to anisotropic conductive rubber. It is not necessary to pressurize constantly, and the heating temperature can be kept lower than the temperature required for soldering.

The following is a detailed supplementary description of various methods for manufacturing the nozzle plate and flow path plate described with reference to FIG.

The nozzle plate is manufactured by electroforming, photosensitive glass etching, silicon etching, micro press or the like. In the case of the electroforming method, as shown in FIG. 17A, the pattern 132 is formed on the substrate 131, and then the Ni 133 of the illustrated shape is attached, and this is grown to grow the nozzle plate 134.
To form. Reference numeral 134a is a nozzle. The electroformed product is peeled from the substrate 131 to obtain a product. The feature of this method is that it is inexpensive and has excellent mass productivity.

In the case of the photosensitive glass etching method, as shown in FIG. 17B, a mask pattern 136 is superposed on the photosensitive glass 135, exposed and etched to form a nozzle plate 137 having a nozzle 137a. To get The feature of this method is that it is possible to increase the length of the nozzle, which increases the accuracy of the ink particle flight direction and
This means that it is easy to ensure the stability of the injection. Also,
Since it is transparent, it can be inspected from the outside even after the head is assembled.

FIG. 17 shows the case of the silicon etching method.
As shown in (C), a resist 139 is applied on the silicon plate 138, a mask pattern 141 is overlaid, and exposure,
By developing and etching, a nozzle plate 141 having nozzles 141a is obtained. The feature of this method is that the processing accuracy is high because the etching rate is low and the dimension control is easy.

In case of the micro press system, FIG.
As shown in (D), the substrate is embossed, stamped and lapped to obtain a nozzle plate 142 having nozzles 142a. The features of this method are that the nozzle length can be increased and the processing accuracy is high.

The flow path plate is manufactured by stainless steel etching, glass etching, silicon etching, photosensitive glass etching, plastic molding, or the like. In the case of the stainless steel etching or glass etching method, as shown in FIG. 18A, a resist 144 is applied on a stainless steel or glass substrate 143, a mask pattern 145 is overlaid, and exposure and etching with an etching solution are performed to form a resist. Is removed to obtain a flow channel plate 146 having a flow channel 146a. The features of this method are low material cost and easy processing.

FIG. 18 shows the case of the silicon etching method.
As shown in (B), a 4-inch-thick Si (100) substrate 147 is coated with a resist 148 such as SiO ₂ and exposed, developed and etched (KOH (10%) aqueous solution at 50 ° C.). , 40 minutes) to obtain the flow channel plate 149 having the flow channel 149a. The feature of this method is that the processing accuracy is high because the etching rate is low and the dimension control is easy.

In the case of the photosensitive glass etching method, as shown in FIG. 18C, a mask pattern 151 is superposed on the photosensitive glass 150, and exposure and etching are performed to form a flow path plate having a nozzle 152a. Get 152. The feature of this method is that the processing accuracy is relatively high and the method is transparent, so that inspection and the like can be performed from the outside.

FIG. 1 shows the case of the plastic molding method.
As shown in FIG. 8 (D), a mold is manufactured by the process shown on the left side. First, a glass substrate 153 is coated with a photoresist 154 in a predetermined pattern, and the surface thereof is sputtered with N.
i155 is formed, and Ni156 is further attached by electroforming. Next, a substrate 157 is attached to the surface and peeled from the glass substrate 153 to obtain a mold 158. At the time of product molding, as shown on the right side, this mold is a flat plate-shaped lower mold 159.
The channel plate 160 provided with the channel 160a is obtained by setting the above and casting the 2P material and then irradiating with UV.
The feature of this method is that it is excellent in mass productivity.

Although the integral type flow path plate has been described in the description of FIG. 15 and subsequent figures, its appearance is shown in FIG.
2 is shown in FIG. 19, as shown in FIG.
The number of parts and processing man-hours are small. The flow channel plate may be not only an integrated type but also a pasted type, an example of which is shown in FIG.

This pasted flow channel plate is obtained by forming a photosensitive resin 162 on the vibration plate 161 by laminating, exposing the pattern through a photomask, and removing unnecessary portions with a solvent. Reference numeral 163 is a pressure chamber and 164 is an ink supply path. The feature of this method is
It is possible to select the optimum material for the performance required for the diaphragm and the partition wall, and to easily control the accuracy of the height of the partition wall.

FIG. 21 shows a positioning method at the time of joining the respective plates constituting the head. This figure shows a case applied to that shown in FIG. 15, and uses two guide pins. Generally, it is said that the alignment accuracy in the pin guide system is about ± 10 μm, and if the positions of the nozzles are decided by the pin guide, the print accuracy will be problematic in a head with high resolution.

However, in the case of the shape like the head of this figure, the positional accuracy between the nozzles is ensured by the nozzle plate itself, and a deviation of about ± 10 μm in the relative position between the flow path and the nozzle is a problem in terms of characteristics. It does not become. In that case, the pin guide method is a simple and effective assembling means. The assembly procedure in the case of this figure is as follows.

Reference numeral 165 is a positioning jig provided with two guide pins 166. Nozzle plate 111, flow path plate 11
2, piezoelectric element 113, and flexible cable 116
Each member is provided with a guide hole corresponding to each of the two guide pins 166, and each member is positioned by fitting these guide holes into the guide pin 166.

In the head structure as described above, if the data such as the head resolution and the part number are engraved at a position visible from the outside of the bonding area of the piezoelectric element bonding surface of the flow path plate, a similar head can be identified. It can be facilitated, and mistakes in parts can be eliminated. Moreover, it does not increase the cost.

[0109]

As described above, according to the present invention, it is possible to mass-produce high-resolution and small-sized ink jet heads at low cost.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of an ink jet head of a first embodiment of the present invention, FIG. 1 (A) shows a standard arrangement of pressure chambers and nozzles, and FIG. 1 (B) and FIG. ) Indicates the arrangement of partition walls.

FIG. 2 is a structural explanatory view of an ink supply path of a first embodiment of the present invention, FIG. 2 (A) shows the one of the present invention, and FIG. 2 (B).
Indicates the conventional one.

3A and 3B are structural explanatory views of another ink supply path of the first embodiment of the present invention, FIG. 3A shows a case of a common ink supply path, and FIG. 3B is an ink supply path separation type. Shows the case.

FIG. 4 is an explanatory diagram of a position setting procedure of a nozzle and an ink supply path according to the first embodiment of the present invention, and FIGS. 4A to 4C show a case where the ink supply path is connected to the center of the pressure chamber. , Fig. 4
(D) and (E) show the case where the ink supply path is connected to a position diagonal to the nozzle.

5A and 5B are comparative explanatory views of the flow path length of the second embodiment of the present invention, FIG. 5A shows the case of the present invention, and FIG. 5B shows the conventional case.

FIG. 6 is an explanatory view of the shape of the head according to the second embodiment of the present invention.

FIG. 7 is a shape explanatory view of another head according to the second embodiment of the present invention.

FIG. 8 is an explanatory view of the shape of a nozzle slanted two-row array type head according to the second embodiment of the present invention.

9A and 9B are operation explanatory views of an inkjet head using a piezoelectric element, FIG. 9A shows a non-operation state, and FIG. 9B shows an operation state.

10A and 10B are operation explanatory views of the inkjet head using electrostatic force, FIG. 10A shows a non-operation state, and FIG. 10B shows an operation state.

11 is an operation explanatory view of the ink jet head using the electrothermal conversion element, FIG. 11 (A) shows a non-operation state, and FIG.
(B) shows the operation.

FIG. 12 is an explanatory diagram of a method for forming a piezoelectric element.

FIG. 13 is a diagram illustrating another method of forming the piezoelectric element.

FIG. 14 is an explanatory diagram of a piezoelectric element and a pressure chamber alignment means.

FIG. 15 is an assembly process diagram of the head, which is shown in FIG.
(G) shows each process in order.

16A and 16B are explanatory views of various connection methods of the flexible cable and the piezoelectric element, FIG. 16A shows a wire bonding method, FIG. 16B shows a thermocompression bonding method, and FIG.
(C) and (D) show the bump bonder method, and FIG.
Shows the anisotropic conductive rubber system, and FIG. 16 (F) shows the anisotropic conductive film system.

FIG. 17 is an explanatory view of various manufacturing methods of the nozzle plate.
17A shows a case of an electroforming method, FIG. 17B shows a case of a photosensitive glass etching method, FIG. 17C shows a case of a silicon etching method, and FIG. 17D shows a micro press. The case of the method is shown.

FIG. 18 is an explanatory view of various manufacturing methods of the flow channel plate, and FIG.
18A shows a stainless steel or glass etching method, FIG. 18B shows a silicon etching method, FIG. 18C shows a photosensitive glass etching method, and FIG.
8 (D) shows a plastic molding method.

19 is a perspective view showing the actual shape of the flow channel plate of FIG.

FIG. 20 is a perspective view showing the shape of a pasted flow channel plate.

FIG. 21 is a perspective view showing a joining method of each plate.

FIG. 22 is a perspective view showing the outline of the structure of various conventional direct type inkjet heads, and FIGS. 22 (A) to 22 (D) show various arrangements of a pressure generation source and pressure chambers.

[Explanation of symbols]

11, 21, 31 Inkjet head 12, 22, 51, 61, 71a, 81a, 91a, 1
11a, 134a, 137a, 141a, 142a
Nozzles 13, 23, 52, 62, 72a, 82a, 92a, 1
12a, 163 Pressure chambers 41a-41c, 42, 53, 63, 164 Ink supply paths 71, 81, 91, 111, 134, 137, 141,
142 Nozzle plates 72, 82, 92, 112, 146, 149, 160
Flow path plate 73, 83, 104, 161 Vibration plate 74, 101, 102, 113 Piezoelectric element 94 Electrothermal conversion element

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masanori Ueda, 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, within Fujitsu Limited (72) Inventor Noboru Takada 1015, Ueda-anaka, Nakahara, Kawasaki, Kanagawa: within Fujitsu Limited ( 72) Inventor Yoshiaki Sakamoto 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (5)

[Claims] 1. An ink jet head having 2n nozzle rows (n is an integer of 2 or more) formed of at least one or more nozzles, wherein the nozzle that prints the highest dot is the first nozzle and the lowest nozzles in that order. When the nozzles for printing the dots are numbered, the nozzle row to which the arbitrary m-th nozzle belongs and the nozzle row to which the (m + n) -th nozzle belong are arranged in proximity to each other, and the m-th nozzle An inkjet head characterized in that a nozzle row to which a nozzle belongs and a nozzle row to which a (m + 1) th nozzle belong belong to each other. 2. The ink jet head according to claim 1, wherein the two pressure chamber rows corresponding to the two nozzle rows that are arranged close to each other with the nozzles facing each other are formed by an ink supply path. An inkjet head characterized by being surrounded all around. 3. The ink jet head according to claim 2, wherein there are a plurality of pressure chamber groups, the ink supply passages surrounding them are separated for each pressure chamber group, and each separated ink supply passage has a different color. An inkjet head that receives supply of ink. 4. A side shoot type or edge shoot type ink jet head having at least one or more nozzles and pressure chambers, wherein the ink jet head is connected to an ink supply path while keeping the pressure chamber width constant. 5. The inkjet head according to claim 4, wherein an isolated partition is provided in the vicinity of the inlet of each pressure chamber of each pressure chamber row sandwiching the ink supply path.