JPH06171088A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To provide an ink jet recording head having an ink flow conduit designed not to have dust staying in a second recession 11. CONSTITUTION:On the channel substrate 1, a channel groove 3 and an ink reservoir 4 are formed by anisotropic etching. An insulation layer 8 and a thick film resin layer 9 are formed on a heater substrate 2. On the thick film resin layer 9, a first recession 10 having a heater provided in its bottom and a second recession 11 for coupling the channel groove 3 and ink reservoir 4 by bypassing the non-etched part of the channel substrate 1 are formed. The formation is effected so that the thick film resin layer 9 is made thick, and the actual cross-sectional area of the second recession 11 becomes larger than the actual cross-sectional area of the channel groove. Thus, small dust passed through a filter and having the size of the order of the actual cross-sectional area or below of the channel groove 3 can be precluded from staying in the second recession 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink flow path of an ink jet recording head.

[0002]

2. Description of the Related Art As an ink jet recording head conventionally used, for example, Japanese Patent Application No. 3-348525.
Japanese Patent Application Laid-Open No. 4-118345 discloses a conventional example. FIG. 4 is a cross-sectional view of a conventional ink jet recording head in which the vicinity of an ink ejecting element is cut perpendicularly to the axial direction of a channel groove. 1 in the figure
Is a channel substrate, 2 is a heater substrate, 3 is a channel groove,
4 is an ink reservoir, 5 is a nozzle, 6 is an unetched portion, 7 is a heater, 8 is an insulating layer, 9 is a thick resin layer, 10
Is the first recess, 11 is the second recess, L1 is the height of the channel groove, and L2 is the thickness of the thick film resin layer. In the recording head shown in FIG. 4, the flow path connecting the channel groove and the ink reservoir is formed with the second concave portion 1 formed in the thick film resin layer 9.
It is formed by 1.

A channel groove 3 and an ink reservoir 4 are formed in the channel substrate 1 by anisotropic etching, and the opening of the channel groove 3 serves as a nozzle 5. A heater 7 is formed on the heater substrate 2, and an electrode for supplying a drive current to the heater 7, a protective film, etc. are formed, but details of these are omitted. Further, on the heater substrate 2, the insulating layer 8 and the thick film resin layer 9 are formed.
A thermosetting resin or the like is used for the thick film resin layer 9. These two substrates are joined and cut into individual head chips to be separated, whereby a recording head is manufactured.

The first recess 10 is called a pit and is formed by patterning the insulating layer 8 and the thick resin layer 9 to suppress the lateral growth of bubbles generated on the heater 7, It is intended to prevent deviation of the nozzle from the nozzle 5 and suction of air. In addition, the second recess 11
Corresponds to the unetched portion 6 of the channel substrate 1 by leaving the insulating layer 8 at the bottom in order to protect the wiring, the driving circuit (not shown) and the like arranged under the insulating layer 8 from the invasion of the ink. The thick film resin layer 9 is formed at a position by patterning. Here, the thickness L2 of the thick film resin layer 9 corresponds to the height of the flow path portion of the second recess.

In the conventional ink jet recording head having such an ink flow path, there occurs a phenomenon in which dust continues to stay in the second concave portion 11 connecting the channel portion and the ink reservoir, and the ink supply is hindered. .
If the ink supply is interrupted, the ink droplets ejected from the nozzles 5 communicating with the recess become very small, or the ink droplets are not ejected, and the recorded image deteriorates. The reason why dust continues to stay in the second recess 11 that connects the channel portion 3 and the ink reservoir 4 is that the thickness L2 of the thick film resin layer 9 forming the ink reservoir is thin and dust cannot pass through the second recess 11. This is because.

The ink supplied to the ink jet recording head has its dust removed by a filter (not shown) provided outside the ink jet recording head.
However, the size of the dust to be removed is only a certain size or more. In order to remove minute dust, it is necessary to reduce the opening diameter of the filter. However, if the opening diameter of the filter is reduced, the fluid resistance of the filter will increase, which will hinder the inflow of ink, and the cost of creating the filter. The problem arises that For this reason, the filter is designed not to remove the finer dust than is necessary. The filter that has been used conventionally removes dust that does not stagnate in the channel groove 3, and normally removes only dust that is larger than that which does not stagnate in the channel groove having a height of 30 to 60 μm. Was there.

On the other hand, the thickness L2 of the thick film resin layer 9 is about 5 μm when it is the thinnest in the past, which is very thin. Therefore, the ink flow path of the second concave portion 11 is narrow, and the dust that has passed through the filter cannot pass through the second concave portion 11 and stays in this portion. Therefore, there is a problem that the ink droplets ejected from the nozzle 5 become very small, or the ink droplets are not ejected and the recorded image deteriorates.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide an ink jet recording head having an ink flow path in which dust does not stagnate in the second recess 11. It is what

[0009]

According to the present invention, a channel substrate having an ink reservoir and a plurality of channel grooves formed therein, and a plurality of recesses having a thick film resin layer for connecting the ink reservoir and each channel groove are formed. In an ink jet recording head for adhering a heated heater substrate to form an ink flow path, the concave section is formed so that its effective cross-sectional area is larger than that of the channel groove. Is.

[0010]

According to the present invention, the effective cross-sectional area of the recess connecting the ink reservoir formed on the heater substrate and each channel groove is made larger than the effective cross-sectional area of the channel groove for ejecting ink. The dust having a size equal to or smaller than the effective cross-sectional area of the channel groove that has passed through does not stay in the recess.

[0011]

FIG. 1 is a sectional view showing an embodiment of an ink jet recording head of the present invention, in which the vicinity of an ink ejecting element is cut perpendicularly to the axial direction of a channel groove. In the figure, the same parts as those in FIG. L3 is the second
The distance from the end of the concave portion 11 from the heater substrate side to the unetched portion on the channel substrate side, L4 is the second concave portion 1
1 is the distance on the ink reservoir side. Although the structure is almost the same as that of FIG. 4, the thickness L2 of the thick film resin layer 9 is formed to be large, so that the height of the second recess 11 is increased. Then, this second recess 11
The effective cross-sectional area of is larger than that of the channel groove 3. According to such an ink jet recording head, a small dust having a size equal to or smaller than the effective cross-sectional area of the channel groove 3 that has penetrated into the head through the opening of the filter (not shown) is larger than the effective cross-sectional area of the channel groove 3. Since it can pass through the second recess 11 having an effective cross-sectional area, dust does not stagnate in the second recess 11.

A first specific example of an embodiment of the ink jet recording head of the present invention will be described. Since the shape of dust that enters the head is indefinite, it is conceivable that dust 12 having an elongated shape may pass in the cross-sectional direction of the channel groove in a considerably bad state, as shown in FIG. 2 (A). In consideration of such a case, in the first specific example, even if dust corresponding to the triangular height of the channel groove 3, that is, the depth of the channel groove 3 passes through the filter, The film thickness L of the thick resin layer 9 on the heater substrate 2 forming the ink flow path of the second recess so that dust does not stagnate in the recess.
2 can be made thicker than the depth of the channel groove 3 so that dust having a size equal to or less than the depth of the channel groove does not stay in the second recess 11.

In the first specific example, the depth L of the channel groove 3 is
1 was 34.6 μm, and the thickness L2 of the thick film resin layer 9 of the heater substrate was 40 μm, which was thicker than 34.6 μm of L1. Further, the insulating layer has a thickness of 5 μm, the distance L3 from the end of the second recess 11 from the heater substrate side to the unetched portion on the channel substrate side is 80 μm, the thickness d of the unetched portion 6 is 20 μm, and the second The distance L4 on the ink reservoir side of the recess 11 was set to 80 μm. Such an ink jet recording head can be manufactured by the method described in JP-A-1-148560.

An ink jet recording head having the above-mentioned dimensions is assembled together with a printed circuit board, a heat sink, etc. so that it can actually operate on the printer, and this is mounted on the printer to repeatedly print an image, and the image quality, especially,
Image quality defects such as missing dots and thin lines were evaluated. As an evaluation method, after 20 prints are continuously printed in a normal environment, maintenance operations such as wiping and priming are performed. Such a printing experiment was repeated 20 times to print 400 sheets in total, and then the ink cartridge was replaced 10 times to evaluate image quality defects of 4000 prints in total.

As a result of evaluating the image quality deterioration due to the stagnation of dust when the ink jet recording head of the first specific example is used, several heads print 4000 sheets,
The dots corresponding to a certain number of nozzles were slightly smaller than the other nozzles, but this was not a problematic defect.
This is because the thickness L2 of the thick resin layer is 40 μm, which is thicker than the depth of the channel groove, which is 34.6 μm, so that the dust in the flow path of the second recess does not become stagnant.

A second specific example of an embodiment of the ink jet recording head of the present invention will be described. In the second specific example, as shown in FIG. 2B, the shape of dust entering the head is considered to be circular in the cross-sectional direction of the channel groove, which corresponds to the diameter of the inscribed circle of a triangle. It is assumed that the dust 13 passes through the filter. The film thickness L2 of the thick film resin layer of the heater substrate forming the ink channel of the second recess
Is formed thicker than the diameter of the inscribed circle in the cross-sectional direction of the channel groove where the ink is ejected, so that dust having a size equal to or less than the diameter of the inscribed circle of the channel groove does not stay in the second recess 11.

In the second specific example, the thick film resin layer 9 on the heater substrate 2 with respect to the channel groove depth L1 of 34.6 μm.
The film thickness L2 was set to 25 μm, which is thicker than the diameter 23 μm of the inscribed circle in the cross-sectional direction of the channel groove 3. An ink jet recording head having such dimensions was prepared and evaluated in the same manner as in the above-mentioned first specific example. In the ink jet recording head of this specific example, the result of evaluating the image quality deterioration due to the stagnation of dust did not show a problematic defect as in the first specific example. This is the film thickness L of the thick film resin layer.
2 is 25 μm, which is thicker than the inscribed circle diameter of 23 μm in the cross-sectional direction of the channel groove, so that dust is not stagnation in the flow path of the second recess.

A third specific example of an embodiment of the ink jet recording head of the present invention will be described. A third specific example is a case where the shape of dust is considered to be easily deformed. As shown in FIG. 2C, when the area of a triangle in the cross-sectional direction of the channel groove 3 is S, as shown in FIG. As shown in D), the thickness L of the thick film resin layer with respect to the ink flow passage width W of the thick film resin layer.
2 is formed thicker than S / W. As a result, the ink flow path cross-sectional area Sb of the thick film resin layer becomes larger than the cross-sectional area S of the channel groove, and dust having a size equal to or smaller than the cross-sectional area S of the channel groove has a larger cross-sectional area Sb. The second recessed portion 1 can be deformed and passed through the second recessed portion 11.
No longer stagnant at 1.

In the third embodiment, the cross-sectional area S of the channel groove is
Since the channel groove is an isosceles triangle as shown in FIG. 3A, can be calculated from the depth L1 of the channel groove and the base angle α. The depth L1 of the channel groove is 34.
6 μm. Since the channel groove 3 is formed by anisotropic etching, the base angle α is constant and α = 54.7 °. From these values the width of the triangle is 49 μm,
The cross-sectional area S of the channel groove is calculated as S = 847.7 μm ² . Furthermore, the cross-sectional shape of the ink flow path of the thick film resin layer is shown in FIG.
As shown in (B), it is rectangular, and the ink flow path width is W = 5.
4 μm, the thickness L2 of the thick film resin layer is 20 μm, the ink flow path cross-sectional area Sb of the thick film resin layer is 1080 μm ^2, and the ink flow path cross-sectional area Sb of the thick film resin layer is smaller than the cross-sectional area S of the channel groove. I made it bigger.

An ink jet recording head having such dimensions was prepared and evaluated in the same manner as in the first specific example. In the inkjet recording head of the third specific example, the result of evaluating the image quality deterioration due to the stagnation of dust did not show any problematic defect, as in the first and second specific examples. This is because the thickness L2 of the thick resin layer is 20 μm.
m, which is larger than S / W = 15.7 μm obtained by dividing the cross-sectional area S of the channel groove by the ink flow channel width W of the thick film resin layer,
This is because dust no longer stays in the flow path of the second recess.

In the above-mentioned first to third specific examples, when the invading dust has an elongated shape in the cross-sectional direction of the channel groove, or is considered to be circular in the cross-sectional direction of the channel groove,
When it was considered that the shape of the dust was likely to be deformed, the film thickness L2 of the thick film resin layer 9 was obtained and prototyped and evaluated. The film thickness L2 of the thick film resin layer 9 is the same as that of the specific example described above. The size is not limited. That is, depending on the size of the opening of the filter, the size of the dust contained in the ink, the quality of the dust, etc., an intermediate value of the dimensions used in the above-described specific examples, or a dimension larger or smaller than them. It is also possible to

[0022]

As is apparent from the above description, according to the present invention, the second groove for connecting the channel groove and the ink reservoir is formed.
Since the effective cross-sectional area of the recessed portion is formed to be larger than the effective cross-sectional area of the channel groove that ejects ink, dust that is equal to or smaller than the effective sectional area of the channel groove that has passed through the filter will not enter the second recessed portion. Since there is no stagnation, the ink droplets ejected from the nozzles are small, and there is an effect that it is possible to reduce the deterioration of the recorded image that the ink droplets are not ejected.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of an inkjet recording head of the present invention, in which the vicinity of an ink ejecting element is cut perpendicularly to the axial direction of a channel groove.

FIG. 2 is an explanatory diagram of a relationship between a cross section of a channel groove and dust.

FIG. 3 is an explanatory diagram of a relationship between a channel groove and a thick film of a thick resin layer in a third specific example.

FIG. 4 is a cross-sectional view of a conventional inkjet recording head in which the vicinity of an ink ejecting element is cut perpendicularly to the axial direction of a channel groove.

[Explanation of symbols]

1 channel substrate, 2 heater substrate, 3 channel groove, 4 ink reservoir, 5 nozzle, 6 unetched part, 7 heater, 8 insulating layer, 9 thick film resin layer, 1
0 first recess, 11 second recess, 12, 13, 14
Dust, L1 height of channel groove, L2 thickness of thick film resin layer, L3 distance from end of second concave portion from heater substrate side to unetched portion on channel substrate side, L4
Distance of the second recess on the ink reservoir side.

Claims (1)

[Claims] 1. A channel substrate having an ink reservoir and a plurality of channel grooves formed therein is bonded to a heater substrate having a thick film resin layer and having a plurality of recesses for connecting the ink reservoir and the respective channel grooves. An inkjet recording head for forming an ink flow path, wherein the recess has an effective cross-sectional area larger than that of the channel groove.