JPH0839802A - Ink jet printing head - Google Patents

Abstract

PURPOSE:To enhance the printing quality while increasing the recording speed by preventing the production of a splash without increasing the fluid resistance of an ink passage. CONSTITUTION:In an ink jet printing head having an ink passage 40 communicating with an ink chamber 30 storing liquid ink at one end thereof and closed at the other end thereof by a deep end wall 21 and heating the ink charged in the ink passage by the heating resistor 50 attached to the deep end wall of the ink passage to produce an air bubble on the heating resistor to emit an ink droplet from an ink emitting orifice, the width on the deep end wall side of the ink passage is made larger than that on the ink chamber side thereof and the ratio of the distance La from the deep end wall of the ink passage to the end part of the heating resistor and the total length Lb of the heating resistor is set to La/Lb >=0.5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bubble jet recording type ink jet printer head used in a non-impact printer, and in particular, it is possible to prevent the occurrence of splash due to a decrease in fluid resistance of an ink flow path, The present invention relates to an inkjet printhead capable of improving quality and increasing printing speed.

[0002]

2. Description of the Related Art A conventional ink jet print head will be described below with reference to FIG. 5A and 5B show an ink jet printer head according to a conventional example. FIG. 5A is a partial plan view and FIG.
It is CC sectional drawing of.

In these drawings, in a conventional ink jet printer, a wall forming plate 200 having a plurality of parallel rectangular cutouts is attached to a surface of a substrate 10 so that the ink chamber 30 communicates with the substrate 10. A plurality of ink flow paths 400 are formed, and on the substrate 10,
The heating resistor 50 is provided at a position close to the innermost wall 201 of the ink flow path 400, and the orifice plate 60 is mounted on the substrate 10 via the wall forming plate 200. The ink ejection port 61 is formed at a position corresponding to the resistor 50.

Liquid ink 70 is stored in the ink chamber 30, and the ink 70 supplied from the ink chamber 30 is filled in the ink flow path 400 (FIG. 6). reference).

Further, the heating resistor 50 is constructed so as to generate Joule heat by applying a driving pulse. The Joule heat at this time is E [J], and the heating resistor 5
Assuming that the electric resistance of 0 is R [Ω], the energization voltage is V [V], and the energization time is t [sec], the Joule heat E [J] generated by the heating resistor 50 is E = V ² / R × It is represented by the formula t.

FIG. 5 shows one channel of a conventional ink jet printer head. Actually, a plurality of channels having the same structure as above are continuously formed in the vertical direction of FIG. 5 (a).

Next, the printing operation of the conventional ink jet printer head having such a structure will be described with reference to FIG.
A description will be given with reference to (a) to (d). In the state of FIG. 7A, a drive pulse is applied to the heating resistor 50,
When the heating resistor 50 is heated, the ink 70 above the heating resistor 50 is heated and boiled by the Joule heat at this time, and bubbles 71 are generated on the heating resistor 50 as shown in FIG. To do. Then, the pressure of the bubble 71 causes the ink droplet 72 to be ejected from the ink ejection port 61.

Next, the greatly expanded bubble 71 bursts, and as shown in FIG. 6 (c), the ink droplet 72 is ejected from the ink ejection port 61 with the tail 74 formed.
At this time, on the heating resistor 50, some of the remaining bubbles 71 are cooled and condensed by the surrounding ink 70. Due to the bursting and condensation of the bubbles 71, the ink chamber 30
Ink flows from the side and the ink ejection port 61 side toward the rear end wall 201 side where the bubble 71 existed.

Then, as shown in FIG. 3D, the ejected ink droplet 72 is separated into a main droplet 73 and a tail 74, and adheres to the same position on a recording paper (not shown) to form a recording dot. . On the other hand, the bubbles 71 in the ink flow path 400 are completely extinguished, and the ink flow path 400 is again filled with the ink 70.

[0010]

In the conventional ink jet printer head having the above structure, the ink flow path 40 is used.
Since the heating resistor 50 is attached to a position close to the rear end wall 201 of No. 0, the bubble 71 is generated and disappears in the vicinity of the rear end wall 201 of the ink flow path 400. Then, when the bubble 71 is ruptured and condensed, the ink 70 has flowed into the bubble 71 from the ink ejection port 61 side and the ink chamber 30 side, as shown in FIG. 7A.

In this case, the ink 70 flowing toward the bubble 71 collides with the rear end wall 201 of the ink flow path 400 and is repelled as shown in FIG.
Since the shape of 00 is rectangular, the ink 70 bounced back to the inner end wall 201 flows toward the ink ejection port 61 without any reduction in kinetic energy, and is different from the ink droplet 72, so-called splash. 75 was generated.

Since the splash 75 is ejected in a direction different from that of the ink droplet 72, a satellite dot 77 different from the recording dot 76 is formed on the recording paper as shown in FIG. However, there was a problem that

Here, since the splash 75 becomes remarkable as the fluid resistance of the ink flow path 400 decreases,
That is, if the ink supply time is shortened and the recording speed of the inkjet printer head is increased by narrowing the overall width of the ink flow path 400, the fluid resistance of the ink flow path 400 is reduced and the print quality is reduced. It will drop significantly. Therefore, in the conventional ink jet printer head, in order to prevent the generation of the splash 75, it is necessary to widen the width of the entire ink flow path 400 to some extent to increase the fluid resistance of the ink flow path 400.
There is a problem that there is a limit to the increase in the recording speed of the inkjet printer head.

Further, as shown in FIG. 9, when ink droplets caused by the splash 75 adhere to the periphery of the ink ejection port 61, the ink droplets act as nuclei to induce ink leakage 78, and the ink leakage 78 causes the ink to leak. There is a problem that the directionality of the droplet 72 is generated, which also deteriorates the print quality.

Incidentally, JP-A-63-281853 and 2
No. 81854 proposes an inkjet printer head having a configuration in which a plurality of heat generating resistors are arranged at a predetermined interval in a continuous ink flow path having no innermost wall.
With such a configuration, splashing of bubbles does not occur and ink does not bounce back at the time of condensation, and it is possible to prevent the occurrence of splash. However, in the ink jet printer head having such a configuration, when the adjacent channels are driven substantially at the same time, the ink flow generated in one channel affects the ink flow in the other channel, and the ink flow in the other channel is affected. When the kinetic energy of the generated ink flow is large, there is a problem in that the directionality of the ink droplets in the other channel occurs and the print quality deteriorates.

Therefore, as a result of various studies, the splash 75 is formed by relaxing the kinetic energy of the ink 70 repelled by the back end wall 201 in the vicinity of the back end 201 of the ink flow path 400. It has come to be found that it is possible to prevent the occurrence of. Then, the width of the ink flow path 400 on the rear end wall 201 side is made wider than the width on the ink chamber 30 side and / or a predetermined distance is provided between the rear end wall 201 and the heating resistor 50. ,
It has been found that the kinetic energy of the ink 70 repelled by the back end wall 201 can be relaxed without increasing the fluid resistance of the ink flow path 400.

The present invention has been made in view of the above circumstances, and it is possible to prevent the occurrence of splash without increasing the fluid resistance of the ink flow path, thereby improving the printing quality and recording speed. An object of the present invention is to provide an inkjet printer head capable of achieving high speed.

[0018]

In order to achieve the above object, an ink jet printer head according to claim 1 comprises:
One end communicates with an ink chamber that stores liquid ink, and the other end has an ink flow path closed by a rear end wall, and the ink filled in the ink flow path is stored in the ink flow path. In the ink jet printer head that heats by a heat generating resistor attached to the back end wall side of the ink, generates bubbles on the heat generating resistor, and ejects ink droplets from an ink ejection port, the back end wall side of the ink flow path. Is wider than the width on the ink chamber side.

According to another aspect of the present invention, an ink jet printer head has one end communicating with an ink chamber for storing liquid ink, and the other end having an ink flow path closed by a rear end wall. The ink filled in the flow path is heated by the heat generating resistor attached to the inner end wall side of the ink flow path, bubbles are generated on the heat generating resistor, and ink droplets are ejected from the ink ejection port. In the inkjet printer head described above, the ratio of the distance La from the back end wall of the ink flow path to the end of the heating resistor and the total length Lb of the heating resistor is set to La / Lb ≧ 0.5.

Further, in the ink jet printer head according to a third aspect of the present invention, the width of the ink flow passage on the rear end wall side is made wider than the width on the ink chamber side, and the heat generation resistance is increased from the rear end wall of the ink flow passage. The ratio of the distance La to the body end and the total length Lb of the heating resistor is set to La / Lb ≧ 0.5.

[0021]

According to the ink jet printer head of the present invention having the above-mentioned structure, the width of the ink passage on the innermost wall side is made wider than the width on the ink chamber side, so that when the bubble bursts and contracts, Part of the ink that has flowed in and bounced back to the innermost wall does not flow toward the ink ejection port, but flows while turning along the side wall of the ink flow path.
As a result, the kinetic energy of the ink repelled by the back end wall is reduced, and the occurrence of splash is prevented. Further, since only the width on the back end wall side is widened, it is possible to prevent the occurrence of splash without increasing the fluid resistance of the ink flow path.

Further, the distance La from the back end wall of the ink flow path to the end of the heat generating resistor and the total length L of the heat generating resistor.
The ratio of b is set to La / Lb ≧ 0.5, and the distance La under such a condition is provided between the back end wall and the end of the heating resistor.
By opening, the ink flowing toward the back end wall collides with the back end wall through this distance La when the bubbles are burst and condensed. By passing this distance La, the kinetic energy of the ink flowing toward the back end wall is relaxed, whereby the kinetic energy of the ink repelled to the back end wall is reduced, and the occurrence of splash is prevented. Moreover, since the width of the ink flow path is not widened, it is possible to prevent the occurrence of splash without increasing the fluid resistance of the ink flow path.

[0023]

Embodiments of the ink jet printer head of the present invention will be described below with reference to the drawings. FIG.
FIG. 3 is a partial cross-sectional perspective view showing an inkjet printer head according to an embodiment of the present invention. 2A is a partial plan view showing the present inkjet printer head, and FIG. 2B is a sectional view taken along the line AA of FIG.

In the ink jet printer head of this embodiment, the width of the ink flow path on the rear end wall side is made wider than the width on the ink chamber side, and the distance La from the rear end wall to the end portion of the heat generating resistor is The ratio of the total length Lb of the heating resistor is La /
The configuration is such that Lb ≧ 0.5. Further, in the present embodiment, the same parts as those of the related art are designated by the same reference numerals and detailed description thereof will be omitted.

In FIGS. 1 and 2, reference numeral 20 denotes a wall portion forming plate in which a plurality of ink flow paths 40 are formed.
The ink flow path 40 has a shape in which the width on the rear end wall 21 side is linearly widened from the end of the heat generating resistor 50 toward the rear end wall 21, and is wider than the width on the ink chamber 30 side.
Here, the back end wall 21 side refers to at least the range from the back end wall 21 to the end of the heating resistor 50 on the ink chamber 30 side.

There is no particular problem with the width on the side of the rear end wall 21 as long as it does not interfere with the adjacent channel, but it is preferably bounced back to the rear end wall 21 which causes a splash. The size is such that the kinetic energy of the ink 70 can be reduced and the ejection force when the bubble 71 bursts can be secured.

Further, in the ink jet printer head of this embodiment, as shown in FIG. 2A, the distance La from the back end wall 21 to the end of the heating resistor 50 and the heating resistor 5 are set.
The ratio of the total length Lb of 0 is La / Lb ≧ 0.5. Here, the upper limit of La / Lb ≧ 0.5, which is the ratio of the distance La from the back end wall 21 to the end of the heating resistor 50 and the total length Lb of the heating resistor 50, is not particularly limited. . However, if the distance La from the back end wall 21 to the end of the heating resistor 50 is made too long, the ejection force when the bubble 71 bursts decreases and the recording speed decreases, so 1 ≧ La / Lb. It is preferable that ≧ 0.5.

FIGS. 1 and 2 show one channel of the present ink jet printer head. Actually, a plurality of channels having the same structure as above are continuously formed in the vertical direction of FIG. 2 (a). is there.

Next, the operation of the ink jet printer head of this embodiment having the above structure will be described with reference to FIG. FIG. 3 shows the operation of the ink jet printer head, and FIG. 3 (a) shows B of FIG. 2 (b).
-B sectional drawing and the same figure (b) are partial sectional side views.

As shown in FIG. 3A, the width of the back end wall 21 side is made wider than the width of the ink chamber 30 side, so that the ink discharge port 6 can be formed when the bubbles 71 are ruptured and condensed.
A part of the ink 70 flowing from the first side and the ink chamber 30 side toward the air bubble 71 is repelled by the back end wall 21 to draw a large arc as shown by an arrow P in the drawing, and then on the side wall of the ink flow path 40. Turn and flow along. As a result, the kinetic energy of the ink 70 that bounces back to the inner end wall 21 and flows toward the ink ejection hole 61 is reduced, and the occurrence of splash is prevented.

On the other hand, as shown in FIG.
The ratio of the distance La from 1 to the end of the heating resistor 50 and the total length Lb of the heating resistor 50 is set to La / Lb ≧ 0.5, and the distance between the back end wall 21 and the end of the heating resistor 50 is By opening the distance La under such a condition, the ink 70 flowing toward the rear end wall 21 at the time of bursting and condensing of the air bubble 71 reaches the rear end wall 21 via the distance La as shown by an arrow Q in the figure. collide. By passing this distance La, the kinetic energy of the ink 70 flowing toward the back end wall 21 is relaxed, and thereby the kinetic energy of the ink 70 that is repelled by the back end wall 21 and flows toward the ink ejection hole 61 side is reduced. However, the occurrence of splash is prevented.

According to the ink jet printer head of the present embodiment having such a configuration, the width of the ink supply passage 40 on the ink chamber 30 side is not widened, but only the width on the rear end wall 21 side is widened. Since the kinetic energy of the ink 70 that bounces back to the inner end wall 21 and flows toward the ink ejection hole 61 is reduced, it is possible to prevent the occurrence of splash without increasing the fluid resistance of the ink flow path 40. As a result, it is possible to improve the print quality and increase the recording speed.

The ink jet printer head of the present invention is not limited to the above embodiment. In the above-described embodiment, the width on the rear end wall 21 side is linearly widened from the end portion of the heating resistor 50 toward the rear end wall 21, but this is not particularly limited, and for example, , Fig. 4
As shown in FIG. 4A, the rear end wall 21 side is curved in a direction orthogonal to the ink flow channel 40, or as shown in FIG. 4B, the rear end wall 21 side is orthogonal to the ink flow channel 40. The width may be widened on the side of the rear end wall 21 by forming a step in the direction.

Further, in the above embodiment, the width of the ink flow path 40 on the rear end wall 21 side is made wider than the width on the ink chamber 30 side, and the distance La from the rear end wall 21 to the end of the heat generating resistor 50 is La. And the ratio of the total length Lb of the heating resistor 50 to La / Lb
The configuration is ≧ 0.5, but the configuration is not limited to this. For example, when the bubbles 71 are condensed, the ink ejection port 6
When the kinetic energy of the ink 70 flowing from the first side and the ink chamber 30 side toward the bubble 71 is small, the width of the ink flow path 40 on the far end wall 21 side is made wider than the width on the ink chamber 30 side, or From the rear end wall 21 to the heating resistor 50
The kinetic energy of the ink 70 repelled by the back end wall 21 can be obtained by only one of the configurations in which the ratio of the distance La to the end portion and the total length Lb of the heating resistor 50 is La / Lb ≧ 0.5. Can be reduced.

[0035]

As described above, according to the ink jet printer head of the present invention, it is possible to prevent the occurrence of splash without increasing the fluid resistance of the ink flow path, thereby improving the print quality. Thus, the recording speed can be increased.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view showing an inkjet printer head according to an embodiment of the present invention.

FIG. 2 (a) is a partial plan view showing the inkjet printer head of the present invention, and FIG. 2 (b) is a part of FIG.
It is -A sectional drawing.

FIG. 3 is a view showing the operation of the inkjet printer head, in which FIG. 3 (a) is a sectional view taken along line BB in FIG. 2 (b).
FIG. 3B is a partial cross-sectional side view.

4A and 4B are partial plan views showing another embodiment of the present inkjet printer head.

5A and 5B show an inkjet printer head according to a conventional example, in which FIG. 5A is a partial plan view and FIG.
FIG. 4C is a sectional view taken along line CC of FIG.

6A to 6D are partial cross-sectional side views showing the operation of an inkjet printer according to a conventional example.

7 (a) and 7 (b) are partial cross-sectional side views showing the flow of ink at the time of bursting and condensing bubbles of an inkjet printer according to a conventional example.

FIG. 8 is a plan view showing recording dots and satellite dots of an inkjet printer according to a conventional example.

FIG. 9 is a plan view showing an ink droplet ejection state when ink leakage occurs in the conventional inkjet printer.

[Explanation of symbols]

 10 Substrate 20 Wall Forming Plate 21 Inner End Wall 30 Ink Chamber 40 Ink Supply Channel 50 Heating Resistor 60 Orifice Plate 70 Ink 71 Bubble 72 Ink Drop 73 Main Drop 74 Tail 75 Splash 76 Record Dod 77 Satellite Dod 78 Ink Leak

Claims (3)

[Claims] 1. An ink flow path, one end of which communicates with an ink chamber for storing liquid ink, and the other end of which is closed by a rear end wall, wherein the ink filled in the ink flow path is An ink jet printer head which heats by a heat generating resistor attached to the inner end wall side in the ink flow channel to generate bubbles on the heat generating resistor to eject ink droplets from an ink ejection port, The ink jet printer head is characterized in that the width of the innermost wall side of the ink is wider than the width of the ink chamber side. 2. An ink flow path, one end of which communicates with an ink chamber for storing liquid ink, and the other end of which is closed by an inner end wall, wherein the ink filled in the ink flow path is An ink jet printer head which heats by a heat generating resistor attached to the inner end wall side in the ink flow channel to generate bubbles on the heat generating resistor to eject ink droplets from an ink ejection port, The ratio of the distance La from the back end wall of the heating resistor to the end of the heating resistor and the total length Lb of the heating resistor is La / Lb ≧
An inkjet printer head characterized by being set to 0.5. 3. The width of the ink flow passage on the rear end wall side is made wider than the width on the ink chamber side, and the distance La from the rear end wall of the ink flow passage to the end portion of the heat generating resistor, 3. The ink jet printer head according to claim 1, wherein the ratio of the total length Lb of the heating resistor is La / Lb ≧ 0.5.