JPH02155653A - Ink jet recording head and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent a pressure generated at the time of formation of a bubble or an ink displacement attendant on the pressure generation from being dispersed into an ink passage and make it possible to concentrate the pressure or the ink displacement in the direction of a slit-shaped nozzle by providing a wall for separation of heating means from each other, and providing a stopper wall in the vicinity of the heating means. CONSTITUTION:Heating elements 2 are arrayed on a substrate, and electrodes 3 are connected to each of the elements 2 to impress on the element an electric pulse by a driving means (not shown in the figure) with the timing for jetting an ink. The heating elements, electrodes and the like which are not shown in the figure are provided thereon with a protective layer for protection from the in. A separating wall 4 is provided between adjacent ones of the heating elements, the length of the wall being not less than the length W of one edge of the element, desirably 3-10 times the length W. Stopper walls 5 are provided in the vicinity of the heating element between the separating walls, on both sides of the heating element. A slit-shaped nozzle 6 is so positioned as to face the arrayed heating elements 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording head that performs recording by ejecting ink onto a recording medium.

[Conventional technology]

2. Description of the Related Art Inkjet recording apparatuses are known that heat ink and eject the ink using the resulting pressure. This device is capable of generating the pressure necessary for ink ejection in a space as small as the printing pitch, and is located within the ink ejection nozzle, ink supply port, and ink flow path that communicates with the nozzle and supply port. A compact multi-nozzle inkjet recording device was obtained by using the ink heating means as a basic unit and arranging the units in printing bitches.

However, when configuring a head with a large number of nozzles, it is necessary to form each nozzle hole with a uniform size and uniform pitch, and to arrange heat generating stages with precision in each flow path. This required new manufacturing technology, which led to high costs.

As an inkjet device that solves this problem, heating means are arranged in an array on a substrate at a printing pitch, a nozzle plate with slit-shaped nozzle holes is opposed to this substrate, and a predetermined gap is created to form an ink flow path. It is known that they were taken and placed.

In this device, it is not necessary to form ink channels and nozzles corresponding to each heating element, and the above-mentioned interpressure is eliminated.

[Problem to be solved by the invention]

The above inkjet head has a problem in that there is a limit to the pressure caused by the bubbles formed by the heating element and the magnitude of the displacement of the ink accompanying bubble formation, and that the ejection pressure and displacement are insufficient.

An object of the present invention is to solve these problems and provide an inkjet recording head capable of ejecting ink droplets at high speed and a method for manufacturing the same.

[Means to solve the problem]

The inkjet recording head of the present invention includes a substrate on which heating elements are arranged in an array in contact with recording ink and ejecting energy to the recording ink, and the substrate is arranged facing the heating elements with the recording ink interposed therebetween. a nozzle plate in which slit-shaped nozzles are formed across a plurality of heating elements; a separation wall that separates adjacent elements of the array-shaped heating element; and an ink flow path formed by the separation wall near the heating element. and a wall having a lower height than the formed separation wall.

Furthermore, the inkjet recording head manufacturing method of the present invention includes:
a step of forming a first negative-type photosensitive resin layer on a substrate on which an array-shaped heat generating means is formed; a first exposure step of irradiating the photosensitive resin layer with light in a stopper wall pattern; forming a second negative type photosensitive resin layer on the photosensitive resin layer; a second exposure step of irradiating the first and second photosensitive resin layers with light in a separation wall pattern; It is characterized by comprising at least a developing step for removing the photosensitive resin.

[Effect]

The inkjet recording head of the present invention includes a heating element array on a substrate, a separation wall between adjacent heating elements, and a stopper wall with a height lower than the separation wall near the heating elements in a flow path formed by the separation wall. However, a nozzle plate having slit-shaped nozzle holes is arranged on this substrate so that the heating element and the slit-shaped nozzle face each other, and the space between the nozzle plate and the substrate is filled with ink, so that the heating element When the ink is rapidly heated to vaporize the ink and form bubbles, the ink flow generated by bubble expansion in the ink flow path surrounded by the nozzle plate and the substrate separation wall is prevented from flowing in the direction of the ink flow path. The ink can be blocked by the stopper wall, efficiently concentrated in the nozzle direction, and high-speed ink jetting can be performed.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view including a cross section of a substrate on which heating elements used in an inkjet recording head according to the present invention are formed. In the figure, a substrate 1 is made of a material suitable for forming a heating element, such as a single crystal such as glass, ceramics, or silicon, or a metal ring. Heat generating elements 2 are arranged in an array on such a substrate. An electrode 3 is connected to each heating element, and an electric pulse is applied by a driving means (not shown) at the timing of ink ejection. Although not shown, a protective layer against ink is formed on the surface of the heating element, electrode, etc. A separation wall 4 is formed between adjacent heating elements. The length of the separation wall is at least the length W of one side of the heating element, and preferably 3 to 10 times W. Further, a stopper wall 5 is formed near the heating element between the separation walls. The stopper walls are formed on both sides of the heating element as shown in the figure.

FIG. 2 shows the first inkjet recording head according to the present invention.
It is a figure for explaining an example. This figure shows an inkjet recording head formed by overlapping a nozzle plate on the substrate shown in FIG. 1, viewed from the nozzle plate side. In the figure, the slit-shaped nozzle holes 6 are aligned so as to face the heating elements 2 arranged in an array.

FIG. 3 is a cross-sectional view taken along line AA' of the embodiment shown in FIG. 2. A substrate 1 and a nozzle plate 7 are fixed at a predetermined distance, and the space between them is filled with ink 8. This ink 8 is supplied from an ink supply port (not shown). In this embodiment, the distance between the nozzle plate 7 and the substrate 1 is made equal to the height of the separation wall 4.

However, the present invention is not limited to this, and even if a gap is provided between the separation wall 4 and the nozzle plate 7, the effects of the present invention can be obtained. The portion sandwiched between the separation walls forms an ink flow path 9, and the heating element 2 is separated from this ink flow path 9 by a stopper wall 5.

Next, the operation will be explained using this diagram. First, when a signal for ejecting ink is input, a pulsed voltage is applied to the heating element 2 through the corresponding electrode 3. Then, the ink 8 in contact with the heating element 2 is rapidly heated and bubbles 1o are formed.
occurs. The bubble expands rapidly and exerts pressure on the surrounding ink, but because there are stopper walls 5 on both sides of the heating element, the slit-shaped nozzle hole 6 shown by the arrow 12 in FIG.
The flow is concentrated in this direction, and ink droplets 8a are formed from the slit-shaped nozzle holes 6. At this time, the outflow of ink in the direction of the ink flow path 9 is blocked by the stopper wall, so that it is small, and the movement of the bubble 10 is efficiently directed to ink jetting. Next, when heating by preventing heat generation is stopped, the temperature of the bubble decreases, and the bubble contracts and disappears. During this contraction/disappearance process, the area around the heat generation block becomes under negative pressure, and ink is drawn in from the ink channel 9 through the slit-shaped nozzle hole 6 and the gap 7 between the stopper wall 5 and the nozzle plate 7, and new ink is replenished. The ink whose temperature has increased due to the inflow of new ink is cooled, and problems such as variations in bubble formation conditions and generation of unexploited bubbles due to the increase in ink temperature do not occur.

Next, a process for forming walls of different heights used in the inkjet head according to the present invention as shown in FIG. 1 will be explained using FIG. 4. As shown in FIG. 4(a), a first photosensitive resin 22 is applied to a thickness necessary for a stopper wall onto a substrate 21 on which a heating element is formed. This photosensitive resin 22 is made of, for example, polyimide resin or acrylic resin, and in this embodiment, a negative type resin is used. An exposure pattern 23 of a stopper wall is formed on this photosensitive resin 22 in a first exposure step. Next, a new second photosensitive resin 24 is applied onto the photosensitive resin after the exposure process. After that, in a second exposure step, the exposure pattern 25 of the separation wall is applied to the first and second photosensitive resins 22 and 24.
form. After that, in the development process, by removing the resin in the unexposed area, separation walls 2 of different heights are formed on the substrate 21.
6 and a stopper wall 27 are formed.

In this embodiment, the first and second photosensitive resins are preferably made of the same material in order to improve adhesion. Moreover, it is possible to further improve adhesion by applying a coupling agent such as silane before applying the second resin.

〔Effect of the invention〕

As explained above, in the inkjet recording head of the present invention, by forming the separation wall that separates the heat generating means and the stopper wall around the heat generating means, the pressure generated when bubbles are generated and the accompanying ink displacement are suppressed from the ink flow. It is possible to prevent the ink from dispersing in the path and concentrate it in the direction of the slit-shaped nozzle, thereby improving the ink ejection speed and reducing the influence on adjacent heating elements when a slit-shaped nozzle is used. Further, according to the method for manufacturing an inkjet recording head according to the present invention, it is possible to form wall members having different heights with high accuracy, and the inkjet recording head according to the present invention can be easily realized.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a substrate used in an embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams and cross-sectional views of an embodiment of an inkjet recording head according to the present invention, and FIG. 4 is a perspective view of a substrate used in an embodiment of the present invention. FIG. 2 is an explanatory diagram of a method of manufacturing an inkjet recording head according to the method of manufacturing an inkjet recording head according to the present invention. In the figure, 1 is a substrate, 2 is a heating element, 3 is an electrode, 4 is a separation wall, 5 is a stopper wall, 6 is a slit-shaped nozzle hole, and 7
1 is a nozzle plate, 8 is an ink, 9 is an ink channel, 10 is a bubble, 21 is a substrate, 22 is a first photosensitive resin, 23 is an exposure pattern on a stopper wall, 24 is a second photosensitive resin, 25
26 is an exposure pattern of a separation wall, 26 is a separation wall, and 27 is a stopper wall.

Claims (1)

[Scope of Claims] 1. A substrate in which heat-generating elements are arranged in an array in contact with recording ink and provide ejection energy to the recording ink, and the substrate is arranged to face the heat-generating elements with the recording ink interposed therebetween. a nozzle plate in which slit-shaped nozzles are formed across a plurality of heating elements; a separation wall that separates adjacent elements of the array-shaped heating element; and an ink flow path formed by the separation wall near the heating element. An inkjet recording head comprising a wall having a height lower than that of the formed separation wall. 2. a step of forming a first negative-type photosensitive resin layer on the substrate on which the array-shaped heating means is formed; a first exposure step of irradiating the photosensitive resin layer with light in a stopper wall pattern; a step of forming a second negative type photosensitive resin layer on the exposed photosensitive resin layer; a second exposure step of irradiating the first and second photosensitive resin layers with light in a separation wall pattern; A method for manufacturing an inkjet recording head, comprising at least a developing step for removing unexposed photosensitive resin.