JP5292192B2 - Ink discharge head and ink discharge apparatus including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink discharge head which allows stable discharge and has a wide area which can be coated by one scan. <P>SOLUTION: The ink discharge head has: a common ink section forming a flow passage; a feed port arranged in the flow passage to feed ink to the common ink section; a discharge port arranged in the flow passage to discharge the ink from the common ink section; a plurality of communication ports formed along the flow passage between the feed port and the discharge port; a plurality of the ink sections connected to the respective communication ports; a piezoelectric element for changing the volume of the ink sections; a nozzle communicating with the ink sections; and a projecting part for partitioning the periphery of the communication ports. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an ink discharge head and an ink discharge apparatus including the ink discharge head.

  An ink discharge head included in the ink discharge apparatus includes an ink reservoir, a pressure generation chamber that stores predetermined ink, a piezo element that pressurizes the pressure generation chamber, and a nozzle opening that communicates with the pressure generation chamber (for example, a patent). Reference 1). The piezo element sucks the ink in the ink reservoir into the pressure generation chamber, and discharges the ink in the pressure generation chamber as droplets from the nozzle opening. In a general ink ejection head, an ink reservoir is connected to a plurality of pressure generation chambers as a common ink chamber having a flow path (see Patent Document 2).

  Since heat is generated from the pressure generation chamber, the temperature of the ink in the ink reservoir varies. That is, the temperature of the ink in the vicinity of the ink supply port of the ink reservoir is relatively low; the temperature of the ink in a portion away from the ink supply port is relatively high, and bubbles may be generated. For this reason, ink suction into each pressure generating chamber may become unstable. Thus, it has been proposed to circulate ink by providing an ink supply port and an ink discharge port in an ink reservoir to which a plurality of pressure generating chambers are connected (see Patent Document 3). Thereby, the temperature distribution of the ink in the ink reservoir is made uniform.

JP 2005-205285 A JP 2002-283585 A JP 2006-175651 A

  As described above, it has been proposed to make ink temperature distribution uniform by circulating ink through an ink reservoir to which a plurality of pressure generating chambers are connected. Here, as the capacity of the ink reservoir increases, that is, as the length of the flow path of the ink reservoir increases, it is necessary to increase the ink circulation speed in order to make the ink temperature distribution uniform.

  In addition, when the capacity of the ink reservoir increases, that is, when the length of the flow path of the ink reservoir increases, the inventor cannot sufficiently supply ink to a site away from the supply port, and the amount of ink is not uniform. Found out to be. This non-uniform ink amount can be eliminated by increasing the ink circulation speed.

  However, when the ink circulation speed is increased, the ink has a strong inertial force, which causes a problem that it is difficult to suck the ink flowing in the common ink chamber into the pressure generating chamber. For this reason, the ink ejection from the ink ejection head tends to be unstable. Accordingly, the present invention provides means for appropriately sucking ink into each pressure generating chamber while flowing ink at high speed into a flow path-shaped common ink chamber to which a plurality of pressure generating chambers are connected. As a result, an ink ejection head that is stable in ejection and has a wide area that can be applied by one scan is provided.

That is, the present invention relates to the following ink discharge head.
[1] a common ink chamber constituting a flow path; a supply port disposed in the flow path for supplying ink to the common ink chamber; and the flow for discharging ink from the common ink chamber A discharge port disposed in the path; a plurality of communication ports formed along the flow path between the supply port and the discharge port; a plurality of ink chambers connected to each of the communication ports; An ink discharge head comprising: a piezoelectric element that changes a capacity of the ink chamber; a nozzle that communicates with the ink chamber; and a protrusion that partitions the periphery of the communication port.
[2] The ink ejection head according to [1], wherein the protrusion is disposed on the upstream side of the flow path with respect to the communication port.
[3] The ink ejection head according to [1], wherein the shape of the protrusion is a curved surface.
[4] An ink ejection apparatus comprising the ink ejection head according to any one of [1] to [3].

  The ink discharge head according to the present invention makes the temperature distribution and flow rate distribution of the ink flowing therethrough uniform even when the flow path length of the common ink chamber is increased and a large number of pressure generation chambers communicate with the common ink chamber. Can do. Therefore, the ink can be stably sucked into each pressure generating chamber connected to the common ink chamber; the ink can be stably ejected.

  Therefore, according to the ink discharge apparatus including the ink discharge head of the present invention, it is possible to stably apply ink to a large ink application object by one scan.

It is a figure which shows the conventional ink discharge head. 1 is a diagram illustrating an ink discharge head (Embodiment 1) of the present invention. It is a figure which shows the ink discharge head (Embodiment 2) of this invention. It is a figure which shows the ink discharge head (Embodiment 3) of this invention. FIG. 6 is a diagram illustrating an ink discharge head (Embodiment 4) according to the present invention. FIG. 6 is a diagram showing an ink discharge head (Embodiment 5) of the present invention.

  The ink discharge head of the present invention has a common ink chamber that constitutes a flow path, and a plurality of ink chambers that are connected to the common ink chamber. Each of the plurality of ink chambers has a nozzle, and ink droplets are ejected through the nozzle.

  Each of the ink chambers is connected to a common ink chamber through a communication port. Each of the ink chambers is provided with a piezoelectric element (piezo element), and the piezoelectric element can increase or decrease the capacity of the ink chamber. Further, a nozzle is arranged in each ink chamber.

  Specifically, FIG. 1-2 shows the relationship between the common ink chamber 10 and the ink chamber 11. As will be described later, the common ink chamber 10 forms a flow path, and ink flows therein. A communication port 12 is formed in the common ink chamber 10, and the common ink chamber 10 and the ink chamber 11 communicate with each other through the communication port 12.

  When a voltage is applied to the piezoelectric element 13, the capacity of the ink chamber 11 increases, and the ink flowing in the common ink chamber 10 is sucked into the ink chamber 11. When the voltage application to the piezoelectric element 13 is stopped, the capacity of the ink chamber 11 is reduced, so that ink is ejected as droplets through the nozzle 14.

  As described above, the common ink chamber constitutes a flow path. That is, an ink supply port for supplying ink and an ink discharge port for discharging ink are arranged in the common ink chamber; ink can be circulated inside the common ink chamber. There may be one ink supply port or two or more ink discharge ports. The diameters of the ink supply port and the ink discharge port are not particularly limited and may be several mm.

  The flow rate of the ink flowing through the flow path formed by the common ink chamber is not particularly limited, and may be several cc / min or more. According to the present invention, even when the ink flow rate (flow velocity) is increased, the ink is stably taken into each ink chamber, and the ink can be ejected stably.

The size of the flow path formed by the common ink chamber should be appropriately set according to the flow rate and speed of the ink; for example, the cross-sectional area of the flow path may be 0.3 to 10 mm ² ; The depth of the path (depth from the communication port) may be about 0.5 mm; the width of the flow path may be 1 to 1.5 mm. The length of the flow path is set according to the number of ink chambers to be connected, and may be several centimeters or longer. According to the present invention, ink temperature distribution and flow path distribution can be suppressed even if the flow path formed by the common ink chamber becomes longer. Therefore, an ink discharge head that can stably discharge ink is obtained.

  A plurality of openings are formed in the flow path formed by the common ink chamber, and each opening acts as a communication port with each ink chamber. The communication port is arranged along a flow path formed by the common ink chamber. The diameter of the communication port formed in the common ink chamber is not particularly limited, but may be about 40 μm. Although the pitch of a communicating port is not specifically limited, For example, it is 200-300 micrometers. The communication port is disposed between the ink supply port and the ink discharge port.

  The number of communication ports is not particularly limited, but can be several tens or more, and can be 100 or more. According to the present invention, even if the number of ink chambers connected to the common ink chamber is increased, ink can be stably sucked into all the ink chambers.

  Specifically, as shown in FIG. 1A, an ink supply port 20 is formed at one end of the common ink chamber 10, and an ink discharge port 21 is formed at the other end. Thereby, an ink flow in the direction of the arrow 30 shown in FIG. By generating the ink flow, the temperature distribution of the ink is made uniform, and the flow rate distribution is also made uniform.

  Here, with reference to FIGS. 1-1 to 4, a phenomenon that occurs when a protrusion (described later) is not provided around the communication port 12 formed in the common ink chamber 10 will be described. 1-1 to 4 show cross sections of examples of conventional ink ejection heads. FIG. 1-1 is a top view of the ink discharge head as viewed from the side opposite to the nozzle arrangement surface. 1-2 is a cross-sectional view taken along the line AA in FIG. 1-1; FIG. 1-3 is a cross-sectional view taken along the line BB in FIG. 1-1; It is -C sectional drawing.

  FIG. 1-1 shows the ink chamber 11, the piezoelectric element 13, and the common ink chamber 10 for convenience, but these are usually covered with a container. In the common ink chamber 10, an ink supply port 20 and an ink discharge port 21 are provided, and ink circulates (see an arrow 30 in FIG. 1-3). Each of the ink chambers 11 having the piezoelectric elements 13 communicates with the common ink chamber 10 through the communication port 12 (see FIG. 1-2 or FIG. 1-3).

  The piezoelectric element 13 increases or decreases the volume of the ink chamber 11, thereby sucking ink in the common ink chamber 10 or ejecting ink from the nozzle 14. At this time, if the flow of ink flowing through the common ink chamber 10 is fast, it becomes difficult to take ink into the ink chamber 11 through the communication port 12. That is, as the ink flow rate is increased, the ink has a strong inertial force, and even if the piezoelectric element 13 increases the capacity of the ink chamber 11, the ink is not easily sucked into the ink chamber 11.

  Accordingly, the ink discharge head of the present invention is characterized by having protrusions formed around the communication port formed in the common ink chamber. The protrusions only have to be able to stagnate the ink flow in the vicinity of the communication port to some extent. On the other hand, it is preferable that the protrusion does not decrease the speed of the ink flowing into the common ink chamber. In other words, the flow of ink in the vicinity of the communication port is stopped by the protrusion, making it easier to suck ink into the ink chamber through the communication port; ensuring a smooth circulation of the ink, and suppressing variations in ink temperature and flow rate To do.

  The protrusions provided around the communication port of the common ink chamber may be formed so as to completely surround the communication port (see FIG. 4), but are provided only on the upstream side of the flow channel with respect to the communication port. (See FIG. 5). By opening the downstream side, ink is easily provided in the vicinity of the communication port, and the ink is easily sucked into the ink chamber reliably.

  The shape of the protrusion is not particularly limited, and may be a rectangular parallelepiped shape (see FIG. 2) or a protrusion formed with a curved surface (see FIG. 3), but a protrusion formed with a curved surface is better. There is a case. This is because if the protrusion has an acute angle, a part of the ink flow is excessively blocked and negative pressure may be generated. The generation of negative pressure causes bubbles in the ink, which makes the ejection unstable.

  The protrusion length of the protrusion is not limited as long as the above effect can be obtained. For example, the protrusion length is about 10% of the depth of the flow path forming the common ink chamber. For example, if the flow path depth L in FIG. 2-3 is 0.5 mm, the protrusion length l of the protrusion may be 50 to 150 μm.

  The protrusions are not necessarily provided at all the communication ports, and may be provided only at some of the communication ports.

  The ink discharge head of the present invention may have a heater for heating the ink flowing through the common ink chamber (see FIG. 6). By heating the ink in the entire common ink chamber, it is possible to reduce the viscosity of the ink and increase the flow rate of the ink. In particular, the arrangement of the heater may be effective when the viscosity of the ink is high.

  The ink discharge apparatus of the present invention includes the ink discharge head of the present invention. Examples of members other than the ejection head include a stage for moving an object for ejecting ink, a control mechanism for controlling the movement of the stage, and the like.

  According to the ink ejection apparatus of the present invention, it is possible to apply an object having a large application area by a single scan. That is, the common ink chamber of the ink ejection head of the present invention can be a long flow path, and a large number of ink chambers can be connected thereto. In addition, since ink is stably ejected from each ink chamber, it is possible to apply ink over a wide area by one scan.

[Embodiment 1]
FIGS. 2-1 to 5 show cross sections of examples of the ink ejection head of the present invention. FIG. 2A is a top view of the ink ejection head viewed from the side opposite to the nozzle arrangement surface. 2B is a cross-sectional view taken along the line AA in FIG. 2A; FIG. 2C is a cross-sectional view taken along the line B-B in FIG. 2A; FIG. 2-5 is a cross-sectional view taken along the line DD of FIG. 2-3.

  FIG. 2A shows the ink chamber 11, the piezoelectric element 13, and the common ink chamber 10 for the sake of convenience, as in FIG. 1-1. In the common ink chamber 10, an ink supply port 20 and an ink discharge port 21 are provided, and ink circulates (see an arrow 30 in FIG. 2-3). Each of the ink chambers 11 having the piezoelectric elements 13 communicates with the common ink chamber 10 via the communication port 12 (see FIG. 2-2 or FIG. 2-3).

  The piezoelectric element 13 increases or decreases the volume of the ink chamber 11, thereby sucking ink in the common ink chamber 10 or ejecting ink from the nozzle 14.

  As shown in FIG. 2-3, a protrusion 40-1 is arranged around the communication port 12. As shown in FIG. 2-3, the protrusion 40-1 protrudes partway in the depth direction of the common ink chamber 10; as shown in FIG. 2-5, the protrusion 40-1 is disposed across the flow path. Yes.

  The protrusion 40-1 can selectively weaken the flow (arrow 30) of ink supplied from the ink supply port 20 in the vicinity of the communication port 12. For this reason, the flow of ink in the vicinity of the communication port 12 becomes slow, and the ink is easily taken into the ink chamber 11. On the other hand, the protrusion 40-1 does not block the common ink chamber 10, and the ink flow is ensured in the portion without the protrusion. Therefore, variation in ink temperature and variation in amount are reduced.

[Embodiment 2]
3 to 5 show cross sections of other examples of the ink ejection head of the present invention. FIG. 3A is a top view of the ink discharge head viewed from the side opposite to the nozzle arrangement surface. 3-2 is a cross-sectional view taken along line AA in FIG. 3-1, FIG. 3-3 is a cross-sectional view taken along line BB in FIG. 3-1, and FIG. 3-4 is a cross-sectional view taken along line C in FIG. FIG. 3-5 is a cross-sectional view along the line DD in FIG. 3-3.

  The protrusion 40-1 of the ink discharge head according to the first embodiment is a rectangular parallelepiped (FIG. 2-3) and has an acute angle, whereas the protrusion 40-2 of the ink discharge head according to the second embodiment. Is a shape having a curved surface (FIG. 3-3). The other structural members are not different between the first embodiment and the second embodiment.

  As shown in FIG. 3C, since the protrusion 40-2 is a curved surface, a smooth flow can be ensured without hindering the ink flow (arrow 30). Of course, the ink flow in the vicinity of the communication port 12 can be slowed so that the ink can be easily taken into the ink chamber 11.

[Embodiment 3]
4 to 5 show cross sections of further examples of the ink ejection head of the present invention. FIG. 4A is a top view of the ink discharge head viewed from the side opposite to the nozzle arrangement surface. 4B is a cross-sectional view taken along the line AA in FIG. 4A; FIG. 4-3 is a cross-sectional view taken along the line BB in FIG. 4A; FIG. 4-5 is a cross-sectional view taken along the line DD in FIG. 4-3.

  The protrusion 40-1 of the ink discharge head of the first embodiment and the protrusion 40-2 of the ink discharge head of the second embodiment are arranged so as to cross the flow path (see FIGS. 2-5 and 3-5), the protrusion 40-3 of the ink discharge head of Embodiment 3 completely surrounds the communication port 12 in a circular shape. As a result, the ink flow at the communication port 12 can be slowed while making the ink flow smoother.

[Embodiment 4]
FIGS. 5-1 to 5 show cross sections of further examples of the ink ejection head of the present invention. FIG. 5A is a top view of the ink discharge head viewed from the side opposite to the nozzle arrangement surface. 5B is a cross-sectional view taken along the line AA in FIG. 5A; FIG. 5C is a cross-sectional view taken along the line BB in FIG. 5A; FIG. 5-5 is a DD cross-sectional view in FIG. 5-3.

  The protrusion 40-3 of the ink discharge head according to the third embodiment completely surrounds the periphery of the communication port 12 (FIG. 4-5), whereas the protrusion 40-3 of the ink discharge head according to the fourth embodiment. 40-4 surrounds only the upstream side of the communication port 12 in a semicircular shape. As a result, the ink flow is made smoother, the ink flow at the communication port 12 is slowed, and the ink is reliably supplied to the vicinity of the communication port 12.

[Embodiment 5]
FIGS. 6-1 to 5 show cross sections of further examples of the ink ejection head of the present invention. FIG. 6A is a top view of the ink ejection head viewed from the side opposite to the nozzle arrangement surface. 6B is a cross-sectional view taken along the line AA in FIG. 6A; FIG. 6C is a cross-sectional view taken along the line BB in FIG. FIG. 6-5 is a cross-sectional view taken along the line DD in FIG. 6-3.

  A heater 50 is disposed in the common ink chamber 10 of the ink ejection head in the fifth embodiment. The heater 50 heats the ink in the entire common ink chamber 10 to reduce the viscosity of the ink, thereby realizing a smoother flow.

  The ink ejection head of the present invention has a stable ejection despite a large area that can be applied in one scan. Therefore, for example, in the production of a large display, the present invention can be effectively applied to an ink ejection device for forming an organic functional layer.

DESCRIPTION OF SYMBOLS 10 Common ink chamber 11 Ink chamber 12 Communication port 13 Piezoelectric element 14 Nozzle 20 Ink supply port 21 Ink discharge port 30 Ink flow 40-1, 40-2, 40-3, 40-4 Protrusion L Flow path depth l Protrusion Protrusion length

Claims (4)

A common ink chamber constituting the flow path;
A supply port disposed in the flow path for supplying ink to the common ink chamber;
A discharge port disposed in the flow path for discharging ink from the common ink chamber;
A plurality of communication ports formed along the flow path between the supply port and the discharge port;
A plurality of ink chambers connected to each of the communication ports;
A piezoelectric element for changing the capacity of the ink chamber;
A nozzle communicating with the ink chamber;
A protrusion that partitions the periphery of the communication port;
An ink discharge head.   The ink ejection head according to claim 1, wherein the protrusion is disposed on the upstream side of the flow path with respect to the communication port.   The ink ejection head according to claim 1, wherein the shape of the protrusion is a curved surface.   An ink discharge apparatus comprising the ink discharge head according to claim 1.

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