JP3102062B2 - Inkjet recording head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head for ejecting ink, forming flying droplets, and performing recording.

[0002]

2. Description of the Related Art FIG. 9 shows a part of an ink flow path, in which one pressure chamber 4 has three supply paths (2a, 2b, 2).
c) A view of the flow path substrate 1 of the conventional ink jet recording head having a flow path structure as viewed from directly above. FIG. 10 is a cross-sectional view taken along line DD of FIG. 9 in a state where the diaphragm is laminated or adhered to the flow path substrate 1. 9 and 10,
The widths and depths of the three supply paths 2a to 2c are all the same, the viscosity resistance of each supply path is equal, and the flow rate of ink flowing through each supply path is all equal. Further, 2a and 2c are connected to the wall 4a of the pressure chamber 4, and 2b is not connected to the wall 4a.

[0003]

SUMMARY OF THE INVENTION Supply paths (2a to 2c)
In the vicinity of the outlet, the ink flows from a portion having a small cross-sectional area of the flow channel to a portion having a large cross-sectional area, so that the ink flow velocity becomes slow, and turbulent flow is likely to occur depending on the shape of the ink flow channel. As shown in FIG. 9, when the bubbles 8 flow into the side wall of the pressure chamber 4 near the outlet of the supply path 2 c or are generated and stuck, the nozzle 3 is capped on the nozzle surface with the cap 9 and pump suction is performed in the direction of arrow 10. Even if the air bubble discharging operation is performed, the flow of the ink flowing around the air bubbles 8 is not sufficient, so that it becomes turbulent and tends to be non-uniform. Emission is poor.

[0004] Also, island-shaped portions 6 partitioning the supply paths 2a to 2c.
Is formed in a circular arc, the ink flow speed is suddenly reduced at the outlets of the supply passages 2a to 2c, and similarly, there is a problem that the bubble discharging property is poor. This is a particularly important problem when a flow path is formed of a polymer material having a contact angle with ink of 50 degrees or more. If air bubbles remain in the pressure chamber 4, the print quality deteriorates or printing becomes impossible. Therefore, good air bubble discharging property is important in an ink jet recording head.

Accordingly, an object of the present invention is to provide an ink flow path in which the flow of ink near the outlet of the supply path is uniform and which has an excellent bubble discharging property.

[0006]

In order to achieve the above object, an ink jet recording head according to the present invention having three or more supply paths for one pressure chamber connects the viscous resistance of the supply path to the side wall of the pressure chamber. This is characterized in that the ink flow rate is set lower with respect to the remaining supply paths to make the ink flow rate larger than that of the remaining supply paths.

Further, the present invention is characterized in that the change of the ink flow rate at the outlet of the supply path is made gradual, thereby improving the discharge of air bubbles remaining on the side wall of the pressure chamber near the outlet of the supply path.

[0008]

FIG. 1 shows that the present invention has three or more supply paths (2).
a, 2b, 2c) is a perspective view showing a configuration of an ink jet recording head having a channel structure.

As shown in FIG. 1, the ink jet recording head in this embodiment is constructed by laminating or bonding the flow path substrate 1 and the vibration plate 7.

FIG. 2 is a plan view of the ink flow path substrate, and FIG. 3 is a sectional view taken along line AA of FIG.

The supply channels (2a to 2c) have the same flow channel depth d, but the flow channel width is a = c> b. Therefore, the supply path (2a
２2c) are R _2a , R _2b and R _2c ,
_2a = R _2c <R _2b Therefore, the ink flow rate is
The number of supply paths 2a and 2c located on the side wall side is larger, and the number of supply paths 2b located at the center is smaller than the other two (2a and 2c).

As a result, as shown in FIG. 2, even if bubbles 8 flow to the pressure chamber side wall 4a near the outlet of the supply passage 2c or 2a and stay there, the bubble discharging operation such as suction of a pump from the nozzle 3 is performed. If performed, the flow rate of the ink in the supply path 2c is large, so that the bubbles 8 can be discharged without the flow of the ink avoiding the bubbles 8. In this embodiment, the supply channel has a constant flow channel depth and two or more widths. However, the supply channel has two or more flow channel depths having a constant width or a depth and width of 2 or more.
It may be more than kind. The number of supply paths is not limited to three. When there are five supply paths (the supply paths are 2a, 2b,... 2e from the pressure chamber wall side 4a), R _2a = R
_2e <R (other supply paths). Another embodiment of the present invention will be described with reference to FIG. 4 and FIG. 5 which is a cross-sectional view taken along the line BB of FIG.

As shown in FIG. 4, each supply path 2a, 2b, 2
The angle θ of the tip of the island 6 that partitions
By setting the angle to 0 ° or less, the flow speed of the ink flow from the supply paths 2a, 2b, 2c to the pressure chamber 4 is made gentle, whereby the flow can be made uniform. Therefore, the bubbles 8 stagnating on the side walls of the pressure chamber 4 near the outlets of the supply paths 2a and 2c
Can be discharged by a discharge operation such as pump suction.

Further, as still another embodiment of the present invention,
This will be described with reference to FIG. 6 and FIG. 7 which is a cross-sectional view taken along the line CC of FIG.

As shown in FIG. 6, supply paths 2a, 2b, 2c
In the ink flow path whose flow path depth is different from the depth of the pressure chamber 4, the part of the flow path depth of the supply paths 2 a, 2 b, and 2 c is not less than the tip of the island-shaped portion 6 on the pressure chamber 4 side that partitions each supply path. By setting the length, the ink flow speed from the supply passages 2a, 2b, and 2c to the pressure chamber 4 is changed more slowly, and the ink flow can be made uniform.

Therefore, it is possible to discharge bubbles remaining on the side wall of the pressure chamber 4 near the outlets of the supply passages 2a and 2c by a discharge operation such as pump suction. However, the supply paths 2a, 2b,
If the portion of the flow path depth of 2c is too long, the bubbles 8 may be stagnated in that portion .
It is preferable that the length be an appropriate length equal to or longer than the pressure chamber 4 side end .

If the boundary of the ink flow path having two kinds of depths is tapered as shown in FIG. 8, the change in the ink flow rate from the supply path to the pressure chamber becomes more gentle.
The ink flow becomes more uniform. Therefore, the supply path 2a,
The dischargeability of the air bubbles remaining on the side wall of the pressure chamber 4 near the outlet 2c by the discharge operation such as pump suction is further improved.

[0018]

According to the present invention, by individually setting the width or depth of the supply path, extending the shallow portion of the flow path in the supply path, and improving the shape of the island portion separating each supply path, the vicinity of the exit of the supply path. It is possible to improve the discharge property of the air bubbles staying on the side wall of the pressure chamber.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an ink jet recording head including a flow path substrate and a vibration plate.

FIG. 2 is an embodiment diagram of a flow path of the ink of the present invention in which the widths of the supply paths are individually set.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a view showing an embodiment of the present invention in which the shape of an island-shaped portion partitioning a supply path is changed.

FIG. 5 is a sectional view taken along line BB of FIG. 4;

FIG. 6 is a view of an embodiment of the present invention in which a portion of a supply channel having a shallow passage depth is extended.

FIG. 7 is a sectional view taken along the line CC of FIG. 6;

FIG. 8 is a cross-sectional view of the ink flow path of FIG. 7 with tapered boundaries between different flow path depths.

FIG. 9 is a diagram showing the shape of a conventional ink flow path.

FIG. 10 is a sectional view taken along line DD in FIG. 9;

[Brief Description of Symbols] 1 flow path substrate 2a supply path 2b supply path 2c supply path 3 nozzle 4 pressure chamber 5 ink chamber 6 island portion 7 diaphragm 8 bubble 9 cap

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-89649 (JP, A) JP-A-59-167268 (JP, A) JP-A-56-105968 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2/055

Claims (2)

(57) [Claims] 1. An ink jet recording head having three or more supply paths for one pressure chamber, wherein the viscous resistance of the supply path connected to the side wall of the pressure chamber is less than the viscous resistance of the supply path not connected to the side wall of the pressure chamber. An ink jet recording head characterized by being lower than the above. 2. The ink jet recording head according to claim 1, wherein an end portion of the island-shaped portion that partitions each supply path on the pressure chamber side has an angle of 120 ° or less.