JP2004175119A - Ink-jet recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink-jet recording head that is small and gives good printing stability and controls the transformation of a head frame at the time of jetting ink by inserting a reinforcement in a resin head frame. <P>SOLUTION: The ink-jet recording head supports a vibrating board (3) fixing the free end of an oscillator (6) stretching in the vertical direction to the vibrating board (3) and a reinforcement (5) is embedded in a resin head frame (4) holding the fixed end of the oscillator (6) in the almost vertical direction to the vibrating board(3). <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to an inkjet recording head that forms a recorded image by discharging ink droplets on a recording medium, and more particularly, to a structure of a head frame that fixes a vibrator and a diaphragm.

  2. Description of the Related Art Conventionally, there has been proposed an ink jet recording head in which a vibration plate is laminated on a wall surface of a pressure generating chamber communicating with a nozzle, and the vibration plate is pressed by a piezoelectric vibrator to discharge ink droplets and record the ink on a recording medium. (For example, Patent Literature 1) The recording head of Patent Literature 1 includes a nozzle substrate having nozzles, a spacer member in which a pressure generating chamber, a reservoir, and an ink flow path are formed, and a diaphragm laminated in a sandwich shape. The vibrating plate is deformed by the piezoelectric vibrator positioned at a position above, the ink pressure in the pressure generating chamber is increased, and ink droplets are ejected from the nozzles. The head frame constituting the recording head has a piezoelectric vibrator positioned and bonded and fixed, and a frame portion of a diaphragm connected to a free end of the piezoelectric vibrator is bonded and fixed.

JP-A-5-212860

  However, in recent years, the number of nozzles in an ink jet recording head has been increased with the aim of high-speed printing and high definition. The number of vibrators and diaphragms increases due to the multi-nozzles, and the head frame for fixing the vibrators and diaphragms becomes longer. A diaphragm frame portion is bonded and fixed to the head frame, and displacement of the vibrator applies a force to the head frame through the diaphragm. Since the increased force of the vibrator is applied to the extended head frame, the head frame is deformed according to the displacement of the vibrator. Therefore, the amount of deflection of the diaphragm is reduced by the amount of deformation of the head frame, and the amount of ink ejection and the speed of ejection are reduced. In addition, the beam that is supported at both ends has the largest amount of deformation at the center and decreases as it approaches the both ends, so the ejection amount and ejection speed of ink droplets vary depending on the position of the nozzle in the head and the printing quality deteriorates I do.

  To prevent this, it is necessary to increase the rigidity of the head frame and reduce the amount of deformation. However, it is very difficult to change the material of the head frame in consideration of not only the rigidity but also the balance between the damping plate and the adhesiveness with the diaphragm, moldability, and cost. Further, if an attempt is made to improve the strength by enlarging the head frame, the size of the head cannot be reduced because the head becomes large. In particular, when the width of the center beam portion of the head frame is increased, the distance between the parallel nozzle rows is increased, and a problem of print misalignment occurs.

  Therefore, the present invention is intended to solve such a problem. The purpose of the present invention is to suppress deformation of the head frame by using a reinforcing member integrally provided in the head frame, and to increase the ink discharge amount and the ink discharge speed. An object of the present invention is to provide an ink jet recording head which can stabilize at a level and can cope with multi-nozzles.

  In order to solve the above problems, an ink jet recording head according to the present invention includes a nozzle plate in which a plurality of nozzle openings are arranged in a row, and a spacer in which a plurality of pressure generating chambers respectively communicating with the plurality of nozzle openings are formed. A vibration plate forming one side surface of the pressure generation chamber, and a head frame joined to the vibration plate side, wherein the plurality of pressure generation chambers are formed through openings formed in the head frame. The other end of the vibrator is fixed to the head frame via a vibration damping plate such that one end of each of the plurality of vibrators that gives a pressure change to the vibrating plate, and the vibrator is attached to the vibrating plate. In an ink jet recording head vibrating in a direction perpendicular to the diaphragm, one of the walls surrounding the opening of the head frame has a nozzle opening substantially perpendicular to the diaphragm. Comprises a reinforcing plate disposed in a direction along the direction the head frame integrally, the vibrator to the reinforcing plate formed wall opposite the wall, characterized in that it is fixed

  An ink jet recording head according to an aspect of the invention includes a nozzle plate having a plurality of nozzle openings arranged in a row, a spacer having a plurality of pressure generation chambers communicating with the plurality of nozzle openings, and one side surface of the pressure generation chamber. And a head frame joined to the diaphragm side, and a plurality of pressure generating chambers each applying a pressure change to the plurality of pressure generating chambers from an opening formed in the head frame. Inkjet wherein the other end of the vibrator is fixed to the head frame via a vibration damping plate such that one end of the vibrator comes into contact with the vibrating plate, and the vibrator vibrates in a direction perpendicular to the vibrating plate. In the recording head, the head frame is disposed on one of the walls surrounding the opening in a direction substantially perpendicular to the diaphragm and along the direction in which the nozzle openings are arranged. Reinforcement plate integrally provided with the head frame, said vibrator wall which faces the reinforcing plate is formed wall is characterized in that it is fixed.

  As a result, even when the head frame is extended by increasing the number of nozzles, the deformation of the head frame due to the displacement of the vibrator unit is suppressed, and the discharge amount and the discharge speed are transmitted to the diaphragm without impairing the displacement of the vibrator. it can. Further, it is possible to provide a printer capable of high-speed printing by using a multi-nozzle ink jet recording head capable of eliminating variations in the ejection amount and ejection speed at the central portion and both end portions of the head and enabling high-quality printing.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an exploded perspective view of an ink jet recording head according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the entire structure cut in the Y direction.

  Reference numeral (6) denotes a vibrator having a longitudinal vibration mode, which is configured so as to generate a large displacement with a low applied voltage by using a laminated type. The free end of the vibrator (6) is fixed to an island-shaped projection (3b) formed on the diaphragm (3) by an adhesive. The diaphragm (3) has a metal diaphragm frame (3c) fixed to a resin film, and the diaphragm frame (3c) is bonded and fixed to a head frame (4). The vibrator (6) has electrodes formed on opposing surfaces thereof. The electrodes on one surface are electrically connected to the lead electrodes on the vibration damping plate (7), and the other electrode is electrically connected to the connecting member. A lead plate (8) or a circuit board (not shown) draws out from the ink jet type recording head and connects to a drive circuit. The vibration damping plate (7) is made of a free-cutting ceramic and has one surface adhered and fixed to the vibrator (6), and the other surface adhered and fixed to the inner wall of the resin head frame (4) with an adhesive. Have been.

  A voltage of about 30 V is applied to the electrode of the vibrator (6) through the lead electrode and the connecting member, so that the vibrator (6) extends and contracts by about 2 μm in the direction of the arrow (6a), and the island-shaped protrusion (3b) is reduced. The diaphragm (3) is vibrated through this. A reinforcing member (5) made of a metal plate is embedded in the head frame (4) by insert molding in a direction substantially perpendicular to the diaphragm (3). The head frame (4) uses a thermosetting resin exhibiting a high Young's modulus according to the number of nozzles and use conditions.

  As described above, the diaphragm (3) is deformed by increasing or decreasing the voltage to the vibrator (6) to generate a pressure change in the pressure generating chamber (2B). However, if the diaphragm (3) is too soft. When the vibrator (6) is displaced, the compliance of the pressure generating chamber (2b) is large, so that the diaphragm (3) itself is deformed by the force of the pressure generating chamber (6). No effective pressure is generated. In order to obtain an effective pressure, the diaphragm (3) is required to have appropriate rigidity. Therefore, the force applied to the diaphragm (3) by the displacement of the vibrator (6) is also transmitted to the head frame (4). As the vibrator (6) is deformed, the head frame (4) tries to deform in the same direction as the direction of displacement of the vibrator.

  FIG. 3 is a cross-sectional view of the entire structure cut in the X direction. The head frame (4) is configured to accommodate the vibrator (3) in the vibrator opening (4c). Both ends of the head frame (4) are thick and relatively rigid because there are no holes, but the vibrator opening (4c) is easily deformed because the thickness is thin. In particular, when the distance between the nozzle rows is increased, the center beam (4a) of the head frame causes a problem such as printing misalignment, so that the center beam cannot be made thick and it is difficult to increase rigidity. As the number of vibrators (6) and diaphragms (3) increases due to the increase in the number of nozzles, the head frame (4) becomes longer, and when the vibrator (6) expands and contracts, deformation as shown in FIG. 4 occurs. When the head frame center beam (4a) is deformed in the same direction as the displacement direction of the vibrator (6), the head frame center beam (4a) to which the diaphragm frame (3c) is adhered and fixed is deformed together with the diaphragm. (3) also moves in the same direction, and the amount of deflection of the diaphragm (3) is reduced by the amount of deformation of the center beam (4a) of the head frame. Therefore, a decrease in the amount of ink ejected and a decrease in the ejection speed occur. In addition, the beam supported at both ends has a maximum deformation amount at the center and decreases as the distance from both ends decreases, so that the discharge amount and discharge speed of ink droplets vary depending on the position in the head, and the print quality deteriorates. In order to reduce the amount of deformation, it is required to increase the rigidity of the head frame (4).

  One measure is to change the material of the head frame (4) to a material having high rigidity. However, there is a limit to the Young's modulus of the resin molding material, and the material of the head frame is made of a vibration damping plate (7). ), Adhesion to the diaphragm (3), formability, cost, etc., must be taken into account. Many materials having high Young's modulus have poor moldability and very high cost, and there are many problems in terms of availability of materials.

  Here, the function of the reinforcing material (5) will be described. The reinforcing member (5) made of a metal plate is insert-molded integrally with the head frame (4) on the center beam (4a) of the head frame, so that the width of the center beam (4a) of the head frame is increased without increasing the width. Can be raised.

  Since the reinforcing member (5) is arranged in parallel with the nozzle row and continuously from one end of the head frame to multiple ends, high rigidity is obtained for the diaphragm (3). As a result, as shown in FIG. 5, when the vibrator (6) is displaced, the amount of deformation of the head frame center beam (4a) in the vibrator displacement direction (6a) is extremely small, and the displacement of the vibrator (6) is impaired. Without being transmitted to the diaphragm (3). As a result, the target pressure change can be given to the pressure generating chamber (2a), and the required discharge amount and discharge speed of the ink droplet can be secured.

For example, SUS430 has a rigidity of 210 × 10 ⁹ or more, which is 10 times or more higher than a Young's modulus of about 18 × 10 ⁹ Pa of the resin used for the head frame. In general, since the amount of deformation of the beam is inversely proportional to the cube of the thickness of the beam, a high effect can be obtained by extending the reinforcing member in a direction perpendicular to the diaphragm (3) even with a metal plate having an extremely small width. L1 shown in FIG. 6 corresponds to the thickness of the beam.

  Further, as shown in FIG. 7, by extending the reinforcing member (5) in the vibrator displacement direction and directly fixing the reinforcing member (5) to the diaphragm (3), higher rigidity can be obtained. Since the reinforcing material (5) is integrally molded by insert molding, the number of manufacturing steps is small, and a molding material that takes into account the adhesiveness, formability, cost, and the like with the vibration damping plate (7) and the diaphragm (3) is used. It is possible to choose.

  The same effect can be obtained even if the reinforcing member (5) is made of a highly rigid ceramic as well as a metal plate. Further, by using a ceramic heater as the reinforcing plate and increasing the rigidity of the head frame and correcting the temperature of the ink, the ink viscosity can be kept constant even in a low temperature environment, and the ejection characteristics of the ink droplets can be stabilized.

Regarding the problems caused by the insert molding of the reinforcing material (5), it is necessary to make the following. Since the head frame (6), which is a precision component, requires a high degree of dimensional accuracy, a large number of holes (5a) are formed in the reinforcing member (5) to improve the flow so as not to hinder the flow of the resin. Therefore, the flow of the resin at the time of molding is not obstructed, the bias of the resin pressure is eliminated, and the required dimensional accuracy is maintained. Further, it is necessary to select a resin and a reinforcing material having similar thermal expansion coefficients so that the head frame (4) and the reinforcing material (5) do not peel off due to a temperature change. For example, for a thermosetting resin having a coefficient of thermal expansion of 1.3 × 10 ⁻⁵ / ° C., SUS430 is an effective value with an approximate value of 1.1 × 10 ⁻⁵ / ° C.

FIG. 1 is an exploded perspective view illustrating a configuration of an example of the present invention. FIG. 3 is a partial cross-sectional view (Y-direction cross-sectional view) of the embodiment of the present invention. FIG. 2 is a partial cross-sectional view of the embodiment of the present invention (X-direction cross-sectional view). It is a fragmentary sectional view (without reinforcing material, sectional view in the X direction) of the head frame of the prior art. FIG. 3 is a partial cross-sectional view of the head frame according to the embodiment of the present invention (a cross-sectional view in the X direction with a reinforcing material). FIG. 3 is a partial cross-sectional view (Y-direction cross-sectional view) of the embodiment of the present invention. FIG. 3 is a partial cross-sectional view (Y-direction cross-sectional view) of the embodiment of the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Nozzle plate 1a Nozzle opening 1b Nozzle row direction 2 Spacer 2a Reservoir 2b Pressure generating chamber 3 Vibrating plate 3a Supply port 3b Island-like projection 3c Vibrating plate frame 4 Head frame 4a Central beam 4b Supply pipe 4c Vibrator opening 5 Reinforcing material 5a Hole 6 Vibrator 6a Vibrator displacement direction 7 Damping plate 8 Lead plate L1 Reinforcement plate thickness

Claims (4)

A nozzle plate in which a plurality of nozzle openings are arranged, a spacer in which a plurality of pressure generating chambers respectively communicating with the plurality of nozzle openings are formed, and a diaphragm forming one side surface of the pressure generating chamber are laminated. And a head frame joined to the diaphragm side, and one end of a plurality of vibrators that respectively apply a pressure change to the plurality of pressure generating chambers from an opening formed in the head frame and the diaphragm. In an ink jet recording head, the other end of the vibrator is fixed to the head frame via a vibration damping plate so that the vibrator vibrates in a direction perpendicular to the vibrating plate.
A reinforcing plate disposed on one of the walls surrounding the opening of the head frame and substantially perpendicular to the diaphragm and in a direction along an arrangement direction of the nozzle openings, integrally with the head frame; An ink jet recording head in which the vibrator is fixed to a wall opposed to a wall on which is formed.   2. An ink jet recording head according to claim 1, wherein said reinforcing plate is directly adhered and fixed to said diaphragm.   3. The ink jet recording head according to claim 1, wherein a thermal expansion coefficient of the reinforcing plate and a thermal expansion coefficient of the head frame are substantially the same. 2. The ink jet recording head according to claim 1, wherein the vibrator is fixed to a head frame via a damping plate.

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