JPH11129477A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance ink jet efficiency without causing any deterioration of productivity. SOLUTION: A channel forming board 5 comprises a reservoir 8, first and second pressure generating rooms 9, 10 formed on the opposite sides, a supply port 11 for coupling the first pressure generating room 9 with the reservoir 8, a port 13 for coupling the first and second pressure generating rooms 9, 10 on the ink supply port side, and a nozzle conduction hole 14 located oppositely to a nozzle opening 6. A part of ink flowing back to the ink supply port side at the time of jetting an ink drop is fed from the pressure generating room coupling port 13 into the second pressure generating room 10 so that it contributes to ink jet.

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 discharging ink droplets from a nozzle opening by pressurizing ink in a pressure generating chamber communicating with a nozzle opening and a reservoir by a pressure generating means.

[0002]

2. Description of the Related Art In an ink jet type recording head, a pressure generating chamber communicating with a common ink chamber and a nozzle opening is deformed by a pressure generating means, for example, a heating element provided in the pressure generating chamber or a part of the pressure generating chamber. The ink droplets are ejected by applying pressure by a piezoelectric vibrator or the like provided so as to be capable of causing the ink droplets to be ejected. FIG. 4 shows an example of an ink jet recording head using a piezoelectric vibrator as a pressure generating means.
1, a flow path forming substrate 23 for partitioning and forming the pressure generating chambers 22, an elastic plate 24 for sealing one opening, and a nozzle plate 26 having a nozzle opening 25 communicating with each pressure generating chamber 22. Are laminated to form a channel unit 27,
The opening surface 3 of the holder 28 is arranged such that the tip of the piezoelectric vibrator 29 accommodated in the holder 28 contacts the region of the pressure generating chamber 22.
It is configured to be fixed to 0. In addition, the code | symbol 31 in a figure is
4 shows a fixed frame also serving as a shield member.

The flow path substrate 23 allows the ink in the reservoir to quickly flow into the pressure generating chamber when the pressure generating chamber expands due to the piezoelectric vibrator, and the pressure generating chamber when the pressure generating chamber is reduced. In order to efficiently discharge the ink as an ink droplet from the nozzle opening, the pressure generating chamber 22 and the reservoir 20 are provided with an appropriate fluid impedance as shown in FIG. Both are connected by a supply port 21 formed of a narrowed through hole.

If an attempt is made to form such a flow path forming substrate by anisotropic etching, a through hole is formed in most of the silicon single crystal substrate, so that the rigidity of the flow path forming substrate is reduced and assembly is performed. Work becomes difficult. Further, if the thickness of the silicon single crystal substrate is increased in order to increase the rigidity, there is a problem that the etching time is increased and the productivity is reduced.

To solve such a problem, FIG.
As shown in (a) and (b), the silicon single crystal substrate 32
First and second pressure generating chambers 3 each having a concave portion on both sides of
3 and 34, and each of the pressure generating chambers 33 and 34 has a first and a second concave portion that is slightly narrowed and communicates with the reservoir 35.
Ink supply ports 36 and 37 are provided;
A nozzle communication hole 39 formed of a through hole is formed in a region opposed to the above (JP-A-9-123448).

According to this, the ratio occupied by the through holes of the silicon single crystal substrate 32 is reduced, so that rigidity can be ensured. Therefore, the thickness of the silicon single crystal substrate can be reduced.
It is possible to reduce the etching time and the material cost.

[0007]

However, FIG.
As shown in (c), the ink in the first pressure generation chamber 33 that undergoes expansion and contraction due to the displacement of the piezoelectric vibrator corresponds to the fluid impedance of the nozzle communication hole 39 and the first ink supply port 37, respectively. Nozzle communication hole 3 at flow rate Q1, Q2
9 and the first ink supply port 36, and the ink having the flow rate Q1 flowing into the nozzle communication hole 39 further changes to the flow rates Q11 and Q12 corresponding to the fluid impedance between the nozzle opening 38 and the second pressure generating chamber 34. Divide and finally quantity Q1
Only one ink is ejected from the nozzle opening 38 as an ink droplet. For this reason, about 40 to 50% of the amount of change in the volume of the first pressure generating chamber 33 due to the piezoelectric vibrator is ejected as ink droplets, and there is a problem that the ejection opening ratio is low. The present invention has been made in view of such a problem, and an object of the present invention is to provide an ink jet recording head capable of improving the ejection efficiency of ink droplets without lowering the production efficiency. That is.

[0008]

According to the present invention, there is provided a flow passage formed by laminating an elastic plate, a flow passage forming substrate, and a nozzle plate having nozzle openings. In an ink jet type recording head provided with a unit and a pressure generating unit, the flow path forming substrate has a first and a second pressure generating chamber each including a reservoir, and a concave portion formed on the pressure generating unit side and the nozzle plate side. When,
An ink supply port connecting the first pressure generation chamber to the reservoir; a pressure generation chamber connection port connecting the first and second pressure generation chambers at an end on the ink supply port side; A nozzle communication hole was provided at the position.

[0009]

According to the present invention, a part of the ink flowing backward to the ink supply port at the time of ink droplet discharge flows into the second pressure generation chamber from the pressure generation chamber connection port and contributes to the discharge of the ink droplet. As a result, the amount of ink ejected as ink droplets increases.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1 shows an embodiment of the present invention. A piezoelectric vibrator 1 which expands and contracts in an axial direction, which constitutes a pressure generating means, has its tip abutted on an elastic plate 3 which constitutes a flow path unit 2. Head holder 4
It is fixed to. The flow path unit 2 includes an elastic plate 3
, A flow path forming substrate 5 and a nozzle plate 7 having a nozzle opening 6.

The flow path forming substrate 5 has a reservoir 8 formed as a through hole, and first and second pressure generating chambers 9 and 1 formed of concave portions formed on the piezoelectric vibrator 1 side and the nozzle plate 7 side.
0, an ink supply port 11 formed as a concave portion communicating with the first pressure generation chamber 9, and a pressure generation penetrating a wall 12 defining the first and second pressure generation chambers 9 and 10 on the ink supply port side. It is configured by forming a chamber connection port 13 and a nozzle communication hole 14 formed of a through hole facing the nozzle opening 6.

The ink supply port 11 is configured such that its fluid impedance is larger than the impedance of the nozzle opening 6.

In this embodiment, when the piezoelectric vibrator 1 contracts and the first pressure generating chamber 9 expands, ink in the reservoir 8 flows from the ink supply port 11 to the first pressure generating chamber 9 side, and the pressure generating chamber connection port. At 13, the ink is also supplied to the first and second pressure generating chambers 9 and 10 by shunting to the second pressure generating chamber 10.

When the piezoelectric vibrator 1 is extended and the elastic plate 3 is pressed toward the nozzle plate, an amount Q1 of ink flows to the nozzle communication hole 14 side and an amount Q2 of ink flows to the pressure generating chamber connection port 13 side. . The amount Q1 of ink flowing into the nozzle communication hole 14 is supplied to the nozzle opening 6 by Q11 and the second pressure generation chamber 10
Q12 is diverted.

On the other hand, of the amount Q2 of ink flowing into the ink supply port 11 side, the amount Q21 flows from the pressure generation chamber connection port 13 through the second pressure generation chamber 10 into the nozzle opening 6. Since the fluid impedance of the nozzle opening 6 is smaller than the fluid impedance of the ink supply port 11, the amount of ink Q21 flowing into the second pressure generation chamber 10 via the pressure generation chamber connection port 13 passes through the nozzle communication hole 14. As a result, the amount of ink Q12 flowing into the second pressure generating chamber 10 is larger than that of the second pressure generating chamber 10, so that the amount of ink ejected as ink droplets increases.

That is, 60 to 80% of the volume change amount of the first pressure generating chamber 9 is ejected as ink droplets, and the ink jet type recording apparatus has two pressure generating chambers which are affected by one piezoelectric vibrator. The ejection efficiency is greatly improved as compared with the ejection efficiency of the head of 40 to 50%.

In the above-described embodiment, the recording head using a longitudinal vibration mode piezoelectric vibrator as the pressure generating means has been described as an example. A similar effect can be obtained by applying the present invention to a recording head having a heating element for generating bubbles in a chamber.

[0018]

As described above, in the present invention,
In an ink jet recording head including a flow path unit formed by laminating an elastic plate, a flow path forming substrate, and a nozzle plate having a nozzle opening, and a pressure generating unit, the flow path forming substrate is a reservoir. First and second pressure generating chambers formed of concave portions formed on the pressure generating means side and the nozzle plate side; an ink supply port connecting the first pressure generating chamber and the reservoir; and an end on the ink supply port side And the pressure generation chamber connection port for connecting the first and second pressure generation chambers, so that, of the ink that has flowed back to the ink supply port side at the time of discharging the nozzle communication hole ink droplet at a position facing the nozzle opening, A part of the ink flows into the second pressure generation chamber from the pressure generation chamber connection port to contribute to the ejection of ink droplets, and the amount of ink ejected as ink droplets can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of an ink jet recording head of the present invention.

FIG. 2 is an enlarged perspective view showing a flow path forming substrate of the recording head.

FIG. 3 is a diagram schematically showing a flow path formed in the recording head.

FIG. 4 is an assembly perspective view showing an example of an ink jet recording head using a piezoelectric vibrator in a longitudinal vibration mode as an actuator.

FIG. 5 is an enlarged perspective view showing a spacer constituting a recording head.

FIGS. 6A to 6C are a cross-sectional view showing an example of an ink jet recording head, a perspective view showing an enlarged spacer constituting the ink jet recording head, and a diagram schematically showing a flow path.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 piezoelectric vibrator 2 flow path unit 5 flow path forming substrate 7 nozzle plate 8 reservoir 9 first pressure generation chamber 10 second pressure generation chamber 11 ink supply port 13 pressure generation chamber connection port 14 nozzle communication hole

Claims (4)

[Claims] 1. An ink jet type recording head comprising: a flow path unit formed by laminating an elastic plate, a flow path forming substrate, and a nozzle plate having a nozzle opening; and a pressure generating means. A path forming substrate, a reservoir, first and second pressure generating chambers formed of concave portions formed on the pressure generating means side and the nozzle plate side, and an ink supply port connecting the first pressure generating chamber and the reservoir. An ink jet recording head having a pressure generation chamber connection port connecting the first and second pressure generation chambers at an end on the ink supply port side, and a nozzle communication hole at a position facing the nozzle opening. 2. The ink jet recording head according to claim 1, wherein a fluid impedance of the nozzle opening is set smaller than a fluid impedance of the ink supply port. 3. The ink jet recording head according to claim 1, wherein said pressure generating means is constituted by a piezoelectric vibrator. 4. The ink jet recording head according to claim 1, wherein said pressure generating means is constituted by a heating element.