JPS63242645A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To stabilize delivery of ink and to improve recording quality, by forming a step section starting from a delivery port forming section in a member for forming a liquid path and setting a specific relation between the height of the delivery port, the height of the member between the upper end of the delivery port and the step section, and the length of the step section in the direction of the liquid path. CONSTITUTION:A recording head is prepared by forming a liquid path wall 2 of photosensitive resin onto a substrate 1 mounting a delivery energy generating means, then laminating a covering board 3 having a step section thereon to form a liquid path 5. The step section is formed to satisfy a relation: a<=2h<=b, where (h) is the height of a delivery port 4, (a) is the height between the upper end of the delivery port and the step section and (b) is the length of the step section in the direction of the liquid path. In such ink jet recording head, excessive ink is held in the step section and does not adhere around the delivery port, thus eliminating bad influence of excessive ink onto delivery and providing high quality stable recording with high speed.

Description

Detailed Description of the Invention (Field of Industrial Application) □ The present invention relates to an inkjet recording head, and more particularly to an inkjet recording head capable of high-speed and stable recording.

[Conventional technology]

An inkjet recording head used in an inkjet recording method in which recording is performed by ejecting ink usually has an ejection port 4 for ejecting ink, which communicates with the ejection port, as illustrated in FIG. 3(a), for example. A liquid path (not shown) is provided.

In such an inkjet recording head, it is common to form the ejection ports with high surface precision by cutting or the like to stabilize the ink ejection direction and improve the print quality. As shown in Fig. 3(b), there is a two-stage cutting process (Japanese Unexamined Patent Publication No. 61-22
955)) to improve surface accuracy. In other words, in this method, the first cutting to cut part of the member forming the liquid path upstream of the discharge port formation position, and the second cutting to cut the remaining part downstream from this, are performed sequentially to achieve surface accuracy. This forms the discharge port 4. In FIG. 3, reference numerals 1.2 and 3 indicate a substrate, a liquid path wall, and a cover plate, respectively, as liquid path forming members.

However, in such an inkjet recording head, even if the ejection openings are formed with high precision, recovery operations are required when ejecting ink during recording, particularly during ink ejection during high-speed recording, or when ink clogging occurs. As a result, unnecessary ink adheres to the area around the ejection port, and this gradually accumulates, resulting in the formation of an ink pool 6 around the ejection port as shown in the third figure. Such ink pools have negative effects on ejection, such as reducing the ink ejection speed and making the ink ejection direction unstable, reducing the accuracy of ink landing, and as a result, can cause printing quality to deteriorate, such as print wobbling. It had become.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned points. An object of the present invention is to provide an inkjet recording head that eliminates the effects of the above, stabilizes ejection, and improves recording quality.

(Means for Solving the Problems) The above objects of the present invention are achieved by the following present invention.

In an inkjet recording head having a liquid path communicating with an ink ejection port, a member forming the liquid path has a stepped portion starting from the ejection port forming portion described in Orr along the liquid path, and the height of the ejection port is When the length is h, the height from the upper end of the discharge port of the member to the stepped portion is a, and the length of the stepped portion in the liquid path direction is b, the relationship that a, b, and h is a≦2h≦b. An inkjet recording head comprising:

(Function) In the inkjet recording head of the present invention having the stepped portion as described above, unnecessary ink is retained in the stepped portion as shown in FIG. Unnecessary ink does not adhere to the vicinity of the ejection openings, and the adverse effect of these unnecessary inks on ejection is eliminated, allowing high-quality recording to be performed at high speed and stably. In the present invention, the liquid path forming member refers to a substrate or a cover plate, which will be described later.

The present invention will be further described below with reference to the drawings.

First, FIG. 1 shows an external view of an example of an inkjet recording head of the present invention, and FIG. 2 shows a sectional view taken along line AA' in FIG. This recording head includes a substrate 1 on which a well-known ejection energy generating means (not shown) is mounted, a liquid channel wall 2 made of a photosensitive resin, etc., and a cover plate having a stepped portion as shown in the figure. 3 are laminated to form a liquid path 5.

Here, the dimensions of the stepped portion are, where h is the height of the discharge port 4, a is the height from the upper end of the discharge port to the stepped portion, and b is the length of the stepped portion in the liquid path direction. b and h are formed so that a≦2h≦b.

In the inkjet recording head of the present invention having such a stepped portion, unnecessary ink is retained in the stepped portion as shown in Figure 4, so unnecessary ink hardly adheres to the vicinity of the ejection opening, and ejection is stabilized. As mentioned above, in order to further improve the removal of unnecessary ink around the ejection port, in this example, the substrate 1, which is a liquid path forming member, is removed.
and the cover plate 3 are made of different materials, for example, the cover plate 3 is made of a material with good wettability to ink, the substrate 1 is made of a material with low wettability to ink, and the cover plate 3 is made of a material with good wettability. By providing the stepped portion, we aim to improve the prevention of ink adhesion around the ejection port. Of course, it goes without saying that the liquid path forming member does not need to be made of different materials.

Next, other embodiments of the present invention are shown in FIGS. 5 to 9, and it goes without saying that the same effects as in the case of FIG. 1 can be obtained on each side.

The example shown in FIG. 5 includes a substrate 1 and a cover plate 3 as liquid path forming members.
A stepped portion having the same shape as that in FIG. 1 is provided on both sides.

In the example shown in FIG. 6, steps are provided on both the substrate 1 and the cover plate 3, as in FIG. 5, but the dimensions of both steps are a1.
a2, bl and b2, al and a2 are respectively a
l, a7≦2h, and b2 are respectively,
, b2≧2h. As described above, in the present invention, a plurality of step portions may be provided. However, in this case, each of the plurality of step portions needs to satisfy the condition a≦2h≦b.

The example shown in Fig. 7 differs from the above-mentioned respective sides in that instead of providing a liquid channel wall, a liquid channel groove is formed on the substrate 1 by etching or machining, and a step similar to that in Fig. 1 is formed therein. A liquid path is formed by laminating cover plates 3.

The example shown in FIG. 8 is a modification of the above-mentioned FIG. 7, in which step portions similar to those in FIG. 6 are provided on both the substrate 1 provided with the liquid channel grooves and the cover plate 3.

In the example shown in FIG. 9, the stepped portion has a gentle shape as shown. As described above, the stepped portion is not necessarily limited to the shape shown in the drawings, but may take various forms as long as it satisfies the condition a≦2h≦b.

(actual h’6 cases) Examples of the present invention are shown below.

Example 1 The inkjet recording head of the present invention as illustrated in FIG. 1 was manufactured by a well-known method using a silicon wafer as the substrate 1, a photosensitive resin as the liquid path wall 2 and the common liquid chamber wall (not shown), and glass as the cover plate 3. Created by. A protective film of 5i02 was formed on the substrate 1, and a well-known electrothermal converter was provided as a means for generating ejection energy, corresponding to each of the ejection ports 4. Furthermore, the stepped portion was provided by cutting on a glass cover plate that has excellent wettability with ink. Of course, various methods can be used to form the stepped portion, such as machining such as cutting or chemical processing such as etching.

The height h of the discharge port is 50 scales, and the step dimensions a and b are:
10J111 N100 ) us for a, +00. for b. 10 recording heads each having a range of .about.200-200 - as shown in Table 1 were prepared, and a printing test described in detail below was carried out using these recording heads. The results are shown in Table 1.

The printing test was carried out by installing the above-mentioned recording head in a recording apparatus as illustrated in FIG. In this FIG. 1θ, what is indicated by the reference numeral 7 is the inkjet recording head of the present invention. This recording head 7 is mounted on a carriage 10. which is movable freely in the X direction on a shaft 14. )H by means of screws or the like. Printing is performed by ejecting ink from the print head 7 in accordance with the movement of the carriage IO. and,
A sub-ink tank 11 that holds ink to be supplied to the recording head 7 through a tube 13 from an ink tank (not shown) is fixed to the carriage IO.

A recording medium 15 such as paper is wound around a platen 16 at a constant distance in front of the recording head 7, and means for moving the recording medium in the Y direction is provided in conjunction with the platen 16. (Transportation means not shown). 10 is a tube that connects the sub-ink tank 11 and the recording head 7, and ink is supplied to the recording head 7 through this tube 8. 12 is a flexible cable for manually inputting print signals to the recording head 7; Reference numeral 17 is a cap unit for blocking ink in the recording head 7 from outside air when the recording head 7 is not in a printing state.

The following printing test was carried out using the recording device as described above. The print amount is approximately 21 cm (corresponding to the length of 4 sheets of paper), and the print pattern is the alphabet letters rA, B, C...'', for example, the graphic pattern exemplified by the symbol zO121 or 22 in Figure 10. ”,
Various printing patterns such as "draft two-claw printing (overlapping printing)" were used in combination. Carriage IO speed is 22
The printing was carried out at 0c, p, s (approximately 56.4 cm/s), and the printing amount was 50 lines on F4 size vertical paper, and the printing was performed on 5 to 10 sheets in a row. After repeating this, the accuracy of the landing point of the ink droplets of the printed matter recorded on the paper was measured using an inspection means such as a magnifying glass, and the deviation of the printed matter was observed. Separately, the state of ink seepage and adhesion around the ejection ports on the surface of the recording head was also observed. ``Printing deviation was evaluated based on how many of the 10 recording heads the printing deviation occurred in.

Comparative Example 1 An inkjet recording head similar to that of Example 1 was prepared except that a and b were changed as shown in Table 1, and a printing test similar to that of Example 1 was conducted on this recording head. The results are shown in Table 1.

As is clear from Table 1, a and b are each a≦
a satisfying 2h≦b; 10 μ to 100 μ, and b
; Good results were obtained under all the conditions of the examples of too p to 200μ. On the other hand, under the conditions of the comparative example, there was more ink adhesion around the ejection ports, and the more ink adhesion, the more significant the deterioration of print quality due to print deviation was.

Table 1 (however, h = 50 banks) Implementation judgment for each n = 10 pieces 0: 0/10 head No printing distortion o: 1 to 2
/10 head Slight deviation x: 7 to 10/10 head Significant deviation Example 2 An inkjet recording head was created in the same manner as in Example 1 except that h was 30μ and a and b were as shown in Table 2. A printing test similar to that in Example 1 was conducted using this recording head. The results are shown in Table 2.

Comparative Example 2 An inkjet recording head similar to that of Example 2 was prepared except that a and b were changed as shown in Table 2, and a printing test similar to that of Example 1 was conducted on this recording head. The results are shown in Table 2.

As is clear from Table 2, a and b are each a≦
Good results were obtained under all conditions of the examples satisfying 2h≦b. On the other hand, under the conditions of the comparative example, there was more ink adhesion around the ejection ports, and the more ink adhesion, the more significant the deterioration of print quality due to print deviation was.

Table 2 (h = 50 μs) Implementation judgment for each n = 10 pieces @: O/10 head No printing deviation 0: 1 to 2
/lO head Slight deviation occurrence Δ: 4 to 5/1o head Slight deviation occurrence An inkjet recording head as illustrated in FIG. 8 having a stepped portion was prepared, and the same printing test as in Example 1 was conducted on this recording head. The results are shown in Table 3. In addition, h is 50u, al, a2. bl and bl are al = a2.

b, = bl as al, a2 as 20~1oop,
bo, b, 100-150 scales.

Comparative Example 3 An inkjet recording head similar to that of Example 3 was prepared except that al, a2, b, and bl were set as shown in Table 3, and a printing test similar to that of Example 1 was conducted on this recording head. The results are shown in Table 3.

As is clear from Table 3, a and b are each a≦
Good results were obtained under all conditions of the examples satisfying 2h≦b. On the other hand, under the conditions of the comparative example, there was more ink adhesion around the ejection ports, and the more ink adhesion, the more significant was the deterioration in print quality due to print wobbling.

Table 3 (however, h = 504m) Implementation judgment for each n = 10 pieces @: O/1G head No printing distortion o: l
~2/10 head Slight deviation occurrence Δ: 4 to 5/1O Head Slight deviation occurrence ×: 7 to 10/10 head Significant deviation Note that the above explanation mainly refers to a multi-array type inkjet recording head that has multiple ejection ports. However, the present invention can also be applied to a single array type inkjet recording head having one ejection port.

(Effects of the Invention) As described above, according to the present invention, unnecessary ink adhering to the vicinity of the ejection ports during recording operations, particularly high-speed scanning and high-speed turns of the carriage, is removed.
The negative influence of these unnecessary inks on ejection has been eliminated, making it possible to perform high-quality recording at high speed and stably.

[Brief explanation of the drawing]

FIG. 1 is an external view of an example of an inkjet recording head of the present invention, FIG. 2 is a sectional view taken along line 8-8 in FIG. 1, and FIG.
) and (b) are external views of a conventional inkjet recording head, FIGS. 4 to 9 are external views of other examples of the inkjet recording head of the present invention, and FIG. 1O is an inkjet recording head of the present invention. FIG. 2 is a diagram illustrating an example of a recording device used in a printing test.

Claims (1)

[Claims] (1) In an inkjet recording head having a liquid path communicating with an ink ejection port, a member forming the liquid path has a stepped portion starting from the ejection port forming portion along the liquid path, and When the height of is h, the height from the upper end of the discharge port of the member to the stepped portion is a, and the length of the stepped portion in the liquid path direction is b, then a, b, and h are such that a≦2h≦b. An inkjet recording head characterized by having the following relationship.