JP2009297918A - Liquid discharge head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid discharge head which can maintain the excellent state of a foaming liquid and assure the desired discharge by preventing the foaming liquid from staying near a heater while preventing the foaming liquid whose temperature has been raised on heating from entering and exiting a foaming chamber repeatedly. <P>SOLUTION: The indraft of the foaming liquid to the foaming chamber and effluence therefrom is regulated by installing valve members in the upstream connection used as the foaming solution inlet port to the foaming chamber and in the downstream connection used as the foaming solution outlet port therefrom. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid ejection head that performs recording by ejecting ink in association with the generation of bubbles due to thermal energy or the like, and more particularly to a liquid ejection head that includes a movable separation film that is displaced using the generation of bubbles. Is.

  An ink jet recording apparatus that performs recording by ejecting fine liquid droplets such as ink from a liquid ejection head (hereinafter also referred to as a recording head) and adhering to a recording medium has low running cost and quietness during recording. It is widely used because of its excellent resistance. Further, this ink jet recording type recording apparatus has an advantage that it is possible to perform color recording relatively easily by using a plurality of colors of ink. In the ink jet recording method, a so-called bubble jet (registered trademark) recording method using a heater as a pressure generating element for ejecting droplets is relatively easy to arrange the heaters at a high density. This is an advantageous system for recording resolution.

  On the other hand, in the conventional bubble jet (registered trademark) recording method, since heating is repeated while the heater is in contact with ink, deposits due to scorching of ink may occur on the surface of the heater. In this case, when the amount of deposits increases, there is a possibility that sufficient heat cannot be supplied to the ink at the time of ejection, and good ejection cannot be performed. In addition, when the liquid to be ejected (such as ink) is a liquid that easily deteriorates due to heat, or when it is difficult to obtain sufficient foaming, the method of forming bubbles by direct heating with a heater can provide good ejection. There was also a risk of not being done.

  For such a problem, as disclosed in Patent Document 1, the movable separation film is deformed by foaming the foamed liquid with thermal energy through the movable separation film that separates the foamed liquid and the discharged liquid. A method of discharging has been proposed. The structure of the movable separation membrane and the foaming liquid in this method is such that the movable separation membrane is provided in a part of the nozzle. On the other hand, Patent Document 2 discloses a configuration using a large film that vertically separates the entire recording head. This large movable separation membrane is provided for the purpose of preventing the liquids in the two liquid paths from being mixed with each other by being sandwiched between the two plate members that form the liquid paths.

  In addition, as disclosed in Patent Document 3, in order to efficiently use the deformation of the movable separation membrane for the discharge of the discharge liquid, there is one that regulates the shape and the movable range of the movable separation membrane.

JP-A-55-81172 JP 59-26270 A JP 2000-00973 A

  In an ink jet recording head that uses only a conventional discharge liquid (such as ink), since the droplets are discharged onto the recording medium with a large amount of heat, discharging also functions as a heat exhausting action outside the recording head. . However, in the liquid discharge method using the separation membrane, the heated foaming liquid circulates in the flow path inside the recording head. As described above, since there is no positive heat exhausting action, a rise in the temperature of the foaming liquid and the recording head may be a problem during continuous ejection.

  FIG. 7 is a view showing a foaming chamber 700 of a conventional recording head that deforms the movable separation membrane 800 (see FIG. 8) and discharges the discharge liquid. As shown in FIG. 7, in the foaming chamber 700 in the conventional recording head, an upstream connecting portion 701 that connects the foaming chamber 700 and the supply port 709, and a downstream connecting portion 702 that connects the foaming chamber 700 and the discharge port 710. Had a symmetrical shape.

  FIG. 8A is a cross-sectional view of the foaming chamber 700 during foaming as viewed from the side, and FIG. 8B is a cross-sectional view of the foaming chamber 700 during defoaming as viewed from the side.

  By simply providing the connection part as described above, there is no difference between the inflow resistance and the outflow resistance in the connection part, and both the upstream part and the downstream part have the same shape. Therefore, foaming is performed as shown in FIG. Sometimes the amount of foaming liquid flowing out of the foaming chamber 700 is equal in the upstream and downstream parts. Similarly, as shown in FIG. 8B, the amount of the foaming liquid flowing into the foaming chamber at the time of defoaming is also equal on the upstream side and the downstream side. A foaming liquid supply port 709 and a discharge port 710 are provided in the vicinity of the foaming liquid chamber 700, but the flow is symmetric with respect to the heater 708, so the supply port 709 passes through the foaming chamber 700 to the discharge port 710. There is no one-way flow toward Therefore, the foaming liquid around the foaming chamber 700 repeatedly flows into and out of the foaming chamber 700 and is repeatedly heated.

  As described above, if the foaming liquid near the heater stays or the foaming liquid whose temperature has risen repeatedly enters and exits the foaming chamber, if it is heated excessively and excessively heated, normal foaming is hindered. Or the foaming liquid may be altered. However, none of the ejection methods using the separation membrane proposed so far mentions this problem.

  Therefore, the present invention maintains the good state of the foaming liquid by preventing the foaming liquid from staying in the vicinity of the heater or preventing the foaming liquid in a heated state from repeatedly entering and exiting the foaming chamber, An object of the present invention is to provide a liquid discharge head capable of obtaining a desired discharge.

  Therefore, the liquid discharge head of the present invention includes a discharge port that discharges the first liquid, a first flow channel that communicates with the discharge port, a second flow channel that is separated from the first flow channel, The second flow path is provided with a foaming chamber having an inflow portion into which the second liquid flows in and an outflow portion from which the second liquid flows out, and the second flow path in the foaming chamber is provided with the second flow channel. In the liquid discharge head in which the first liquid flowing in the first flow path is discharged from the discharge port by the foaming action of the liquid, a valve member is provided in at least one of the inflow portion and the outflow portion. It is characterized by being.

  According to the present invention, the valve member is provided in at least one of the inflow portion and the outflow portion of the foaming chamber in which the foaming liquid is foamed when the liquid is discharged. As a result, it is possible to prevent the foaming liquid from staying in the vicinity of the heater or preventing the foaming liquid in a heated state from repeatedly entering and exiting the foaming chamber. It was possible to realize a liquid discharge head capable of obtaining the above discharge.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an exploded perspective view showing the liquid discharge head 1000 of the present embodiment in an exploded manner. A discharge element 101 including a bubble generating element (hereinafter also referred to as a heater), a nozzle, and a discharge port and an electric wiring substrate 102 are arranged on a ceramic plate 100. The common liquid chamber in the discharge element 101 is connected to a flow path provided inside the flow path forming member 110, and an ink supply port of the flow path forming member 110 and an ink tank (not shown) are connected. Ink is supplied from the ink tank to the ejection element 101.

  FIG. 2A is a schematic top view showing the liquid discharge head discharge chip 200 in this embodiment, and FIG. 2B is a cross-sectional view taken along line A-A ′ in FIG. The liquid discharge head 1000 (see FIG. 1) of the present embodiment has a movable separation film that separates the foaming liquid and the discharge liquid, and discharges the discharge liquid by using the displacement of the movable separation film accompanying the foaming of the foaming liquid. To do.

  The discharge chip 200 includes a nozzle plate 201, a first flow path wall 202, a movable separation film 203, a second flow path wall 204, and a heater board 205. A first flow path 206 that is surrounded by the nozzle plate 201, the first flow path wall 202, and the movable separation film 203 and communicates with the ejection port is filled with a recording liquid (first liquid) that adheres to the recording medium and performs recording. Has been. The second flow path 207 surrounded by the heater board 205, the second flow path wall 204, and the movable separation membrane 203 is filled with a foaming liquid (second liquid) that is foamed by heating of the heater 208. The foaming liquid is circulated through a supply port 209 and a discharge port 210 provided through the heater board 205.

  FIGS. 3A to 3F are schematic views showing the ejection principle of the liquid ejection head 1000 of this embodiment. In FIG. 3A, the first flow path is filled with the discharge liquid, and the second flow path is filled with the foaming liquid. When energy is applied to the heater 208 in this state, the heater 208 is rapidly heated, and bubbles 300 due to film boiling are generated in the foaming liquid in contact with the heater 208 (FIG. 2B). The pressure accompanying the generation of the bubbles 300 becomes a pressure wave, propagates the foaming liquid in the second flow path 207, and acts on the movable separation membrane 203 to displace it. With the displacement of the movable separation membrane 203, the discharge liquid in the first flow path 206 moves (FIG. 2C), and discharge starts from the discharge port 303. When the bubble 300 grows rapidly due to the initial high pressure, the movable separation membrane 203 is further deformed to push out the discharge liquid in the first flow path 206 to form the liquid column 301 (FIG. 2D). Thereafter, when the bubble 300 enters the contraction process, the movable separation membrane 203 starts to be displaced in the reverse direction (FIG. 2E), and eventually returns to the initial position. At this time, since the discharge liquid moves in the direction of being drawn into the first flow path 206, the liquid column 301 is cut off to form the main droplet 302 and the satellite 304 (FIG. 2 (f)). The satellite 304 flies toward a recording medium (not shown).

  FIG. 4 is a diagram illustrating a part of the foaming chamber of the second flow path 207 in the liquid discharge head 1000 according to the present embodiment. In the present embodiment, the upstream connecting portion 401 is provided with a valve member 403 that has a small resistance when flowing into the foaming chamber 400 and has a large resistance when flowing out, while the downstream connecting portion 402 has a resistance when flowing into the foaming chamber 400. Each of the valve members 403 has a large resistance and a low resistance when it flows out.

  Fig.5 (a) is sectional drawing which looked at the foaming chamber 400 at the time of foaming from the side surface, and FIG.5 (b) is sectional drawing which looked at the foaming chamber 400 at the time of defoaming from the side surface. These valve members 403 are formed of a metal foil formed by electroforming or the like, and the directions of the free ends of the two valve members 403 are matched. In the upstream connecting portion 401, the valve member 403 is arranged so that the flow path resistance in the direction of exiting the foaming chamber 400 during foaming is greater than the flow path resistance in the direction of entering the foaming chamber 400 during defoaming. Further, in the downstream connecting portion 402, the valve member 403 is disposed so that the flow path resistance in the direction of entering the foaming chamber 400 during defoaming is larger than the flow path resistance in the direction of exiting the foaming chamber 400 during foaming. . Since there is a difference between the inflow amount and the outflow amount on the upstream side and the downstream side, a flow from the supply port 209 to the discharge port 210 is generated as a whole flow. As a result, the foaming liquid circulates such that the foaming liquid enters the foaming chamber 400 from the supply port 209, is pushed out by the foaming action, and exits from the discharge port 210 during defoaming.

  The valve member 403 can be formed by vapor deposition of SiN, or by mounting a member formed of Ni or the like as a separate member by electroforming.

  In this way, a valve member is provided at the upstream connecting portion serving as the inlet of the foaming liquid to the foaming chamber and the downstream connecting portion serving as the outlet of the foaming liquid to restrict the inflow and outflow of the foaming liquid into the foaming chamber. . In this way, by causing the foaming liquid to circulate from the supply port to the discharge port, the foaming liquid stays in the vicinity of the heater, or the foaming liquid in a state where the temperature rises due to heating is repeatedly entered and exited into the foaming chamber. Could be prevented. And the liquid discharge head which can maintain the favorable state of a foaming liquid and can obtain desired discharge was realizable.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. Since the basic configuration of the present embodiment is the same as that of the first embodiment, description thereof will be omitted, and only the characteristic configuration will be described below.

  In this embodiment, the valve member is formed of a thin film of photosensitive resin. The valve member of this embodiment can be manufactured by a tenting method. The tenting method is a general method used when manufacturing a printed circuit board. When manufacturing a printed circuit board, a photosensitive resin that has been processed into a film is attached so as to cover the hole formed in the circuit board. Patterning. In this embodiment, the valve member is formed by applying this tenting method. In this embodiment, this tenting method is applied to form a valve member in the connecting portion.

  FIGS. 6A and 6B are views for explaining a production method of the valve member 604 by the tenting method. As shown in FIG. 6A, the film-like photosensitive resin 603 is stretched so as to linearly cover the space between the base 601 and the base 602. Thereafter, by performing exposure and development as shown in FIG. 6B, the valve member 604 whose free end extends linearly from the surface of the base 601 can be formed. Usually, the photosensitive resin is cured and cured after development. However, when there is a step of applying heat corresponding to curing in the subsequent step, curing after development is not necessarily required.

  In the method for forming the valve member as in the present embodiment, the photosensitive resin is cured to a desired shape at the position where the valve member is formed using photolithography technology, so that it can be installed in the flow path with high positional accuracy. . Further, when the valve member is formed by this method, the valve member can be designed with a high degree of freedom because there is no restriction on the shape due to the manufacturing method of the valve member or the alignment accuracy when the valve member is installed.

  Thus, even when using a valve member formed of a thin film of a photosensitive resin, the foaming liquid stays in the vicinity of the heater or is heated to generate a temperature by causing the foaming liquid to circulate from the supply port to the discharge port. It was possible to prevent the foaming liquid in a state of rising from repeatedly entering and exiting the foaming chamber. And the liquid discharge head which can maintain the favorable state of a foaming liquid and can obtain desired discharge was realizable.

  In each of the above embodiments, the valve member is provided in both the upstream side connecting portion and the downstream side connecting portion. However, the target effect can be obtained even if provided in only one of them.

FIG. 3 is an exploded perspective view showing the liquid ejection head of the present embodiment in an exploded manner. FIG. 5A is a schematic top view illustrating a liquid discharge head discharge chip according to the present embodiment, and FIG. 5B is a cross-sectional view taken along line A-A ′ in FIG. (A) to (f) are schematic views showing the ejection principle of the liquid ejection head of the present embodiment. It is a figure showing the foaming chamber of a part of 2nd flow path in the liquid discharge head of this embodiment. (A) is sectional drawing which looked at the foaming chamber at the time of foaming from the side surface, (b) is sectional drawing which looked at the foaming chamber at the time of defoaming from the side surface. (A), (b) is a figure for demonstrating the production method of the valve member by a tenting method. FIG. 6 is a diagram illustrating a foaming chamber of a conventional recording head that deforms a movable separation film and discharges a discharge liquid. (A) is sectional drawing which looked at the foaming chamber at the time of foaming from the side surface, (b) is sectional drawing which looked at the foaming chamber at the time of defoaming from the side surface.

Explanation of symbols

200 Discharge tip 201 Nozzle plate 202 First flow path wall 203 Movable separation membrane 204 Second flow path wall 205 Heater board 206 First flow path 207 Second flow path 209 Supply port 210 Discharge port 300 Bubble 400 Foaming chamber 401 Upstream connecting portion 402 Downstream side connecting portion 403 Valve member 604 Valve member 1000 Liquid discharge head

Claims (6)

A discharge port for discharging the first liquid, a first flow path communicating with the discharge port, and a second flow path separated from the first flow path,
The second flow path is provided with a foaming chamber having an inflow portion into which the second liquid flows and an outflow portion from which the second liquid flows out,
In the liquid ejection head in which the first liquid flowing in the first flow path is ejected from the ejection port by the foaming action of the second liquid in the foaming chamber.
A liquid discharge head, wherein a valve member is provided in at least one of the inflow portion and the outflow portion.   The liquid discharge head according to claim 1, wherein a valve member is provided in each of the inflow portion and the outflow portion.   The valve member provided at the inflow portion prevents the second liquid from flowing out of the foaming chamber, and the valve member provided at the outflow portion prevents the second liquid from flowing into the foaming chamber. The liquid discharge head according to claim 2.   The liquid discharge head according to claim 1, wherein the valve member is a metal foil.   The liquid ejection head according to claim 1, wherein the valve member is formed by vapor deposition.   4. The liquid discharge head according to claim 1, wherein the valve member is made of a photosensitive resin.

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