JP2002210975A - Ink jet print head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfy both high image quality and high speed recording by preparing at least two kinds of orifice optimal for ejecting ink drops from large size to small size in one print head and selecting an orifice for ejecting ink depending on an image being recorded. SOLUTION: The side shooter type recording head ejecting ink liquid drops in a direction perpendicular to a substrate arranged with heating resistor elements is provided with at least two ink ejection opening arrays each comprising a plurality of orifices where the film thickness of an orifice plate varies continuously with respect to the substrate arranged with heating resistor elements and the distance (OH distance) from the ink ejection opening plane to the substrate is constant. Each ink ejection opening array has a different OH distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink jet print head for ejecting ink to a recording medium to obtain a recorded image.

[0002]

2. Description of the Related Art Ink jet printing apparatuses have been developed in response to recent demands for high-speed printing, high image quality, low noise, and the like for printing apparatuses. In particular, in order to realize high image quality, it is necessary to record a pixel, which is the minimum unit for forming an image, as small as possible and at a high density, and efforts are being made to reduce ink droplets ejected from a print head. However, making the pixels smaller and higher in density increases the number of ink ejection events, which is disadvantageous for high-speed printing. Therefore, two or more types of orifices optimal for ejecting large ink droplets to small ink droplets in one head are provided, and the optimal orifice is selected according to the image to be recorded.
It is necessary to achieve both high image quality and high-speed recording by discharging ink. One of the ink jet recording methods generally used today is a method using a heating resistor element as an ejection energy generating element. The principle of this method is that by giving an electric signal to the heating resistor element, the ink near the electric heat exchange element is instantaneously boiled, and the ink droplets are rapidly formed by rapid bubble growth caused by the phase change of the ink at that time. It is to discharge. This method does not require much space for the discharge energy foaming element, has advantages such as a simple structure of the ink jet print head and easy integration of nozzles.
In this method, for a substrate equipped with a heating resistance element,
The type in which ink droplets are ejected in the vertical direction is called a "side shooter type recording head", and the present invention relates to the structure of this type of side shooter type recording head. JP 4
The ink jet print head described in JP-A-10-10940, JP-A-4-10941, and JP-A-4-100942 disclose ink droplets by communicating bubbles generated by heating a heating resistor element with the outside air. It is characterized by discharging. In these print heads, the distance between the orifice and the heat-generating resistive element that generates ink ejection energy, which has been difficult in the method of manufacturing a conventional edge shooter type recording head (for example, JP-A-62-234941). (Hereinafter referred to as the OH distance) and small droplet recording can be easily achieved. In the print head manufactured according to these inventions, as shown in FIGS. 7A and 7B, a coating that becomes an orifice plate is formed on a substrate in which a dissolvable resin layer is formed in a pattern that becomes an ink flow path. Since the resin layer is applied by spin coating or the like, a uniform film having no variation between a thick portion and a thin portion is obtained. In a print head having such a structure, the amount of ejected ink is determined by the OH distance, so that fixed-quantity droplet recording can be performed stably. However, since the OH distance is limited to only one, it is very difficult to eject a large ink droplet and a small droplet from the same head.

On the other hand, in the edge shooter type print head, in order to change the volume of the ink liquid to be ejected,
A plurality of heating resistance elements are provided for one orifice, and the number of heating resistance elements to be driven simultaneously is controlled by an electric signal. For example, two heating resistance elements are provided, only one is driven to discharge a small ink liquid, and two heaters are simultaneously driven to discharge a large ink droplet, thereby achieving both high image quality and high-speed recording. ing. In the ink jet recording method using a piezoelectric element, the amount of displacement of the element is controlled by a voltage applied to the piezoelectric element provided in the ink chamber adjacent to the orifice, the volume in the ink chamber is controlled, and the ink droplets to be ejected are controlled. The volume is changing.

[0004]

In both of the edge shooter type print head and the piezoelectric element type print head, ink droplets having different volumes, from large to small, must be ejected from the same orifice. The orifice shape is not optimal for each droplet volume. Therefore, a stable ink ejection volume cannot be obtained, and a sufficiently high image quality cannot be realized. Accordingly, it is an object of the present invention to provide a side shooter type recording bed capable of stably ejecting a fixed amount of liquid droplets and ejecting large and small liquid droplets.

[0005]

According to the present invention, there is provided an ink jet print head capable of ejecting large and small droplets, by changing the thickness of an orifice plate continuously with respect to a substrate provided with a heating resistor element. Providing individual and optimal nozzle shapes according to volume in a single print head,
A plurality of desired ink ejection volumes can be stably obtained.

(Operation) According to the first to eighth aspects of the present invention, it is possible to stably obtain a plurality of types of ink ejection volumes within a single print head, and achieve both high image quality and high-speed recording. Can be.

[0007]

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

(Embodiment 1) In this embodiment, in order to continuously change the thickness of an orifice plate, when a resin layer serving as an orifice plate is formed on a substrate provided with a heating resistor element, the substrate is tilted and gravity is applied. It is characterized by using. Alternatively, the method is characterized in that the substrate itself is moved in a circular motion and centrifugal force is used. Alternatively, they are characterized by using them simultaneously. As shown in FIGS. 1A to 1F, first, a weir 2 made of a dissolvable resin is formed on a substrate 1, and then the substrate is tilted from a vertical direction, or the substrate itself is made circular. To move, the angle 7 between the resultant vector direction 6 of gravity and centrifugal force with respect to the normal direction 5 of the substrate 1
Is maintained, the dissolvable resin layer 3 serving as the ink flow path 14 and the resin layer 4 serving as the nozzle member are sequentially formed.

After the resin layer 4 serving as a nozzle member is cured, the weir 2 and the flow path pattern 3 made of the dissolvable resin are all removed. In this manner, an orifice plate surface 8 having a certain inclination 7 with respect to the substrate 1 is formed, and an orifice array 12 having a different distance 11 (hereinafter referred to as OH) from the heating resistor element 9 to the ink ejection port 10 is formed by ink. Two rows are formed on both sides of the supply port 13. In each orifice row 12, an ink flow path 14 and an ink discharge port 10 that are optimally designed according to the ink discharge amount are formed. Of course, not only OH11 but also heat energy control, balance between viscosity and inertia resistance, etc. must be considered for the optimal design.

For example, as shown in FIG. 4, nozzles are arranged at 300 dpi in a long row 15 of OH 11 and a nozzle shape (OH 27 μm) most suitable for obtaining an ink ejection amount of 8 pl.
m, ink ejection aperture diameter 21φ). Nozzles are arranged in the short rows 16 of OH at 600 dpi, and an optimal nozzle design (OH 25 μm) is obtained so as to obtain an ink ejection amount of 4 pl.
m, ink ejection diameter 15φ). By doing this,
According to the required resolution and gradation on the recording medium, it is possible to record a more accurate amount at a more accurate position on the recording medium, and to realize high-quality and high-speed printing.

Here, the distance 17 between the orifice rows formed on both sides of the ink supply port 13 is L [μm], and the angle θ [deg] of the inclination 7 between the substrate 1 provided with the heating resistor element 9 and the orifice plate surface 8. ], The ink supply port 1
Table 1 below shows the difference in OH between the ink nozzle rows 12 arranged in parallel on both sides of No. 3.

[0012]

[Table 1] The interval 17 between the nozzle rows is 200 μm, and the shorter OH16
Is set to 25 μm, the orifice plate is tilted by about 0.5 degrees with respect to the substrate, so that the longer OH
7 μm, 4 pl ink droplets from the short OH orifice and 8 pl from the long OH orifice.
pl of ink droplets can be stably ejected. When tilted to 4 degrees, a nozzle row 15 having an OH close to 40 μm is formed on the opposite side of the ink supply port 13. As described above, it is possible to stably eject ink droplets having different arbitrary ejection amounts as the thickness and inclination parameter of the orifice plate.

Embodiment 2 In this embodiment, in order to continuously change the thickness of the orifice plate, as shown in FIG. 6, (a) a dissolvable resin layer serving as an ink flow path 14 is formed on a substrate. 3 is once applied by spin coating or the like so as to have a uniform film thickness and cured, and then (b) means for forming a plane having a certain inclination 7 with respect to the substrate 1 is taken. Mechanical methods such as cutting drills,
Any of chemical means such as etching and light energy means may be used.

After patterning the dissolvable resin layer serving as an ink flow path, a resin layer 4 serving as a nozzle member was once formed on the substrate 1 so as to have a uniform thickness in the same manner as in (c). Then, (d) it is processed into a plane having a certain inclination 7. In this way, two rows of orifice rows 12 with different OH and a distance 11 from the heating resistance element 9 to the ink discharge port 10 are formed on both sides of the ink supply port 13.

(Embodiment 3) In this embodiment, the thickness of the orifice plate is continuously changed in the steps as shown in Embodiments 1 and 2, and shown in FIGS. 2 (b) and 4 (b). As described above, the ink supply port 1 is provided on the substrate 1 provided with the heating resistance element.
3 are provided, and three orifice rows 12 having different discharge amounts are provided. One with one nozzle row 20 on one side for each ink supply port 18 and two on both sides
The combination of the nozzles 19 having the nozzle rows 21 and 22 is provided. In such a configuration, the orifice row 21 from which the OH can be reduced to the orifice row 21 from which the OH can be reduced.
Distance from the orifice row 21 to OH
The distance to the orifice row 22 can be further reduced by 20
About 0 μm (distance between columns 20-21)
> Distance between rows 21-22). Here, when the OH of the orifice row 22 is set to 21 μm, the angle θ of the inclination 7 between the substrate 1 provided with the heating resistance element 9 and the orifice plate surface 8
Orifice row 2 in parallel with 3 rows when [deg]
Table 2 below shows the difference between OH of 0, 21, and 22.

[0016]

[Table 2] For example, by setting the inclination 7 of the orifice plate to 2 degrees, the orifice rows 20, 21, and 22 can be formed so that OH is 21, 28, and 70 μm, respectively. Nozzles are arranged in the orifice array 20 at 300 dpi, the nozzle shape (OH 70 μm, ink ejection opening diameter 36φ) most suitable for obtaining an ink ejection amount of 30 pl, and nozzles are arranged in the orifice array 21 at 600 dpi.
Nozzle shape most suitable for obtaining an ink ejection amount of 8 pl,
Nozzles are arranged in the orifice row 20 at 600 dpi, and a nozzle shape (OH 21 μm, ink discharge port diameter 10φ) most suitable for obtaining an ink discharge amount of 2 pl is formed. In this way, despite being a single head, O
The ink discharge amount can be classified into three types, large (30 pl), medium (8 pl), and small (2 pl), depending on the length of H.
According to the resolution and gradation required on the recording medium, it is possible to record an accurate amount at a more accurate position on the recording medium, and high-speed printing with high image quality can be realized.

[0017]

As described above, a plurality of types of ink ejection volumes can be stably obtained within a single print head, and both high image quality and high-speed recording can be achieved.

[Brief description of the drawings]

1A to 1F show a first embodiment of the present invention, and are schematic cross-sectional views showing a method of manufacturing a head shown in FIG.

FIG. 2A is a cross-sectional view illustrating a main part of the first embodiment of the present invention. (B) is a sectional view showing a main part of the third embodiment of the present invention.

FIG. 3 is a schematic diagram showing a basic form of the ink jet print head of the present invention.

FIG. 4A is a plan view showing a main part of the first embodiment of the present invention. (B) is a plan view showing a main part of the third embodiment of the present invention.

FIG. 5 is a perspective view showing a main part of the first embodiment of the present invention.

6 (a) to 6 (d) show a second embodiment of the present invention, and are schematic sectional views showing a method of manufacturing the head shown in FIG. 2 (a) in the order of steps.

FIG. 7 is a schematic sectional view showing a conventional method for forming an orifice plate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Substrate 2 Weir made of dissolvable resin 3 Pattern for ink flow path made of dissolvable resin layer 4 Covering resin layer serving as orifice plate formed on flow path pattern 5 Normal direction of substrate 6 Flow path Direction of the resultant vector of the force applied to the resin layer when forming the coating resin layer to be the orifice plate formed on the pattern for use 7 Angle between the substrate and the orifice plate surface 8 Orifice plate surface 9 Heating resistor element 10 Ink ejection port ( Orifice) 11 Distance from ink discharge port (orifice) to substrate 12, 15, 16, 20, 21, 22 Orifice row 13 Ink supply port 14 Ink flow path 17 Distance between orifice rows 18 One nozzle row on one side Ink supply port 19 Ink supply port with two nozzle rows on both sides

Claims (8)

[Claims] A heat storage layer and a resistor layer are sequentially formed on a substrate, and an individual electrode and a common electrode are arranged on the resistor layer to face each other to form a heating resistor. A thermal head in which a heating resistor element is formed by arranging the heating resistor element, a protective film layer made of an electrically insulating material and an anti-cavitation layer are sequentially applied on the heating resistor element array, and the thermal head is arranged on the thermal head. An orifice plate provided with an orifice, and a flow path portion that forms an ink flow path with the thermal head and the orifice plate, and among the ink introduced into the flow path portion, the ink near the heat generating element is An ink jet print head in which ink droplets are ejected from an orifice by bubbling by rapid heating. An ink jet print head which changes continuously with respect to a substrate provided with a resistance element. 2. An ink discharge port surface (face surface) of the orifice plate has a flatness within the same print head and is ± 15 ° with respect to a substrate provided with a heating resistor element.
2. The ink jet print head according to claim 1, wherein the ink jet print head has the following constant inclination. 3. An ink discharge port surface (face surface) of the orifice plate has a plurality of planes in the same print head, and each plane is ± 15 ° or less with respect to a substrate provided with a heating resistor element. 2. The ink jet print head according to claim 1, wherein said ink jet print head has a constant inclination. 4. An ink discharge port array comprising a plurality of orifices having a constant distance (OH distance) from an ink discharge port surface (face surface) of the orifice plate to a substrate having a heating resistor element. 3. The ink jet print head according to claim 1, wherein the number of rows is equal to or greater than the number of rows, and the OH distance of each ink discharge port row is different. 5. An ink discharge port array comprising a plurality of orifices having a constant distance (OH distance) from an ink discharge port surface (face surface) of the orifice plate to a substrate having a heating resistor element. Rows or more, and the magnitude relation of the OH distance of each row is determined by the ink ejection volume (V
5. The ink-jet printhead according to claim 4, wherein d) is larger than d). OH ₁ > OH ₂ >>...> OH _n Ｖ Vd ₁ > Vd ₂ >
..> Vd _n n is the number of nozzle rows 6. A means for continuously changing the thickness of an orifice plate with respect to a substrate provided with a heating resistor element, wherein a dam made of a dissolvable resin is provided on the substrate,
Similarly, when sequentially forming an ink flow path pattern composed of a dissolvable resin layer and a coating resin layer serving as a liquid orifice plate formed on the flow path pattern, the normal line of the substrate is set to be vertical. After tilting with respect to the direction and curing while maintaining the flatness and tilt by using gravity, removing all the weirs and flow path patterns made of the dissolvable resin, wherein: 4. The ink jet print head according to 1, 2, or 3. 7. A weir made of a dissolvable resin is provided on said substrate as means for continuously changing the thickness of the orifice plate with respect to the substrate provided with the heating resistor element.
Similarly, when sequentially forming an ink flow path pattern made of a dissolvable resin layer and a coating resin layer serving as a liquid orifice plate formed on the flow path pattern, the substrate is made to circularly move, and centrifugal force is applied. The method according to claim 1, wherein after curing is performed while maintaining the flatness and inclination using the method, the weir and the flow path pattern made of the dissolvable resin are all removed. 5. Ink jet print head. 8. The method according to claim 3, wherein the means for continuously changing the thickness of the orifice plate on the substrate provided with the heat generating resistance element is simultaneously performed. 4. The inkjet printhead according to 2, 3 or 4.