JP2007044969A - Inkjet recording head and inkjet recorder equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a structure whereby a fulcrum part of a movable valve is surely held from up and down directions, and also the performance of feeding ink is scarcely deteriorated. <P>SOLUTION: An inkjet recording head has both a plurality of ink delivering ports for delivering the ink, and a nozzle part which communicates with the ink delivering ports. The movable valve with a free end which shifts along with foaming of the ink, and a heater part which is set near the delivering ports to heat and foam the ink are equipped within the nozzle part. A plurality of projections are formed to separate at predetermined intervals at the fulcrum part of the opposite side to the free end of the movable valve. The projections are held between a heater substrate where the heater part is formed and a top plate part opposed to the heater part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inkjet recording head that performs recording by discharging ink, and an inkjet recording apparatus including the inkjet recording head.

  2. Description of the Related Art Conventionally, in an ink jet printer that discharges ink in a discharge nozzle from a discharge port by applying thermal energy to the ink and causing it to foam, the ink is displaced in the discharge nozzle of the recording head as the ink is foamed. Some are provided with a movable valve for controlling the flow of ink.

  The movable valve is formed in a comb-like shape from a free end and a fulcrum portion, the free end is displaced in each discharge nozzle, and the fulcrum portion at the base of the free end is disposed in the common liquid chamber.

In the conventional recording head, the movable valve is directly fixed to the heater board by film formation in a semiconductor process, or the plate-like member is sandwiched between the heater board and the discharge nozzle. (Patent Documents 1 and 2).
Japanese Patent Application No. 9-164498 Japanese Patent Application No.8-146318

  However, at present, in order to stabilize the movement of the movable valve in the vertical direction, no structure has been proposed in which the vicinity of the fulcrum of the movable valve is pressed from above and below. This may hinder the flow of the ink and reduce the discharge performance.

  Further, in the case of a long head having a print width exceeding 1 inch, the number of movable valves increases, and the movement of the movable valves becomes unstable due to limitations on the fixing method.

  The present invention has been made in view of the above problems, and its object is to provide a structure in which the fulcrum portion of the movable valve is surely pressed from the vertical direction regardless of the size of the recording head, and the ink supply performance is hardly deteriorated. Is to realize.

  In order to achieve the above object, an inkjet recording head of the present invention is an inkjet recording head having a plurality of ink ejection ports for ejecting ink and a nozzle portion communicating with the ink ejection port, wherein the nozzle A movable valve having a free end that displaces as the ink foams and a heater portion that is disposed near the discharge port and heats and foams the ink are provided in the section, and a fulcrum opposite to the free end of the movable valve. A plurality of protrusions that are spaced apart from each other at a predetermined interval are provided on the part, and the protrusions are sandwiched between the heater substrate on which the heater part is formed and the top plate part that faces the heater part.

  The ink jet recording apparatus of the present invention includes the ink jet recording head and a head control unit that controls the heater unit to discharge ink from the ink discharge port by heating and foaming ink in the nozzle unit according to image data. And a medium transport unit for transporting the recording medium to which the ink is attached.

  According to the present invention, even when a large load is applied to the movable valve, or when the movable valve is greatly displaced or driven to resonate by being driven at a high frequency, a large load is applied to the fulcrum portion of the movable valve. In addition, since the unnecessary movement is regulated by reliably pressing down from the vertical direction, the discharge characteristics are not adversely affected, and the durability is not lowered.

  Even with a long head with a print width exceeding 1 inch, the fulcrum portion corresponding to each valve portion of the movable valve can be pressed, so the same effect as described above can be obtained regardless of the length of the head. It is done.

  Another effect is that the protrusions are arranged at a smaller distance than the discharge port so as not to obstruct the nozzle flow path, so that foreign matter that floats in the head and causes non-discharge can be prevented without obstructing the ink flow. It is also possible to trap between the protrusions.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

  The embodiment described below is an example of means for realizing the present invention, and should be appropriately modified or changed according to the configuration of the apparatus to which the present invention is applied and various conditions without departing from the spirit of the present invention. Thus, the present invention is not limited to the following embodiment.

  FIG. 1 is a perspective view showing a configuration in the vicinity of a discharge nozzle in an ink jet recording head according to a preferred embodiment to which the present invention is applied. 2 is a top view of the vicinity of the discharge port in the ink jet recording head of FIG. 1, and FIG. 3 is a side sectional view of the vicinity of the discharge port of the ink jet recording head of FIG.

  1 to 3, the heater board 2 is provided with a plurality of heaters 11 for heating and foaming the ink in the discharge nozzles 12 for each discharge nozzle 12. The heater 11 is made of a resistor such as tantalum nitride, having a thickness of 0.01 to 0.5 μm and a sheet resistance of 10 to 300 Ω per unit square. An electrode (not shown) such as aluminum for energization is connected to the heater 11, and a switching transistor (not shown) for controlling energization is connected to the heater 11 on one side. The drive of the switch transistor is controlled by an IC including a circuit such as a control gate element, and the switch transistor is driven in a predetermined pattern by a signal from the outside of the head.

  A discharge nozzle 12 formed corresponding to each heater 11 communicates with each of the discharge ports 1, and each discharge nozzle 12 communicates with the common liquid chamber 6.

  The discharge nozzle 12 is formed in a hollow cylindrical shape with its periphery formed by a heater board 2 and a nozzle partition 4 which is divided into individual nozzles, a nozzle bank 13 having a thickness of about 5 to 10 μm, and a nozzle top plate 5 having a thickness of about 2 μm. It is configured.

  The movable valve 3 has a free end 14 extending toward the discharge port 1 and a fulcrum portion 15 disposed in the nozzle flow path 10. Each fulcrum portion 15 is connected to a support member 16, and the support member 16 is attached to the heater board 2 via the valve seat 8. The nozzle top plate 5 is affixed to a top plate member 17 made of Si or the like, and the top plate member 17 includes an ink supply opening (not shown) formed by anisotropic etching or the like. Ink is configured to be able to be introduced into the nozzle channel 10 from the supply liquid chamber 6. The ink supplied from the nozzle flow path 10 to each discharge nozzle 12 is heated by the heater 11 disposed at a predetermined position in the discharge nozzle 12 to be foamed. Along with the foaming, the ink starts to move in the discharge nozzle 12 and the movable valve 3 is displaced at the same time to control the ink flow.

  Ink droplets are ejected from the ejection port 1. The fulcrum portion 15 of the movable valve 3 is configured such that the protruding column 7 and the valve seat 8 formed on the support member 16 made of the same material are opposed to the heater board 2 and the heater board 2 at the height of the nozzle partition 4. It is supported so that it may pinch | interpose between the nozzle top plates 5 which do.

  Next, the protrusion support | pillar 7 is demonstrated.

  As described above, the protruding column 7 plays the role of pressing the movable valve 3 from the top and bottom and improving the adhesion of the valve, but also plays the role of trapping foreign matter floating in the ink flow path in the head.

  4 and 5 are diagrams for explaining the dimensional relationship between the movable valve 3 and the protruding column 7.

  4 is a cross-sectional view of the ejection port, and FIG. 5 is a view of the ink jet recording head as viewed from the ejection port side.

C = √ (A ² + B ² ) where C is the dimension width A, height B, and the length of the diagonal line of the discharge port 1. When the foreign matter is larger than C, the foreign matter cannot be discharged from the discharge nozzle 12 and may remain in the discharge nozzle 12. If the foreign matter stays in the discharge nozzle 12, it may cause the nozzle to be clogged, resulting in a problem that the image formation is not performed normally. Therefore, it is necessary to prevent foreign matter larger than C from being taken into the discharge nozzle.

Therefore, the interval L4 between the protrusion columns 7 is set as follows.
L4 <C = √ (A ² + B ² ) (Condition 1)
As a result, it becomes possible to supply ink into the nozzle flow path 10 without entering the nozzle flow path 10 with a foreign substance having a cross-sectional area larger than the flow path of the nozzle. It is possible to perform stable image formation without any problems.

  Next, the diameter L1 of the protrusion support 7 will be described. As described above, the protrusion support 7 has a role of trapping foreign matter. However, even if the interval between the protrusion struts 7 is shortened, if the diameter of the protrusion struts 7 is large, the ink flow into the nozzle channel 10 may be difficult.

  6 and 7 are diagrams for explaining the ease of ink flow due to the difference in the diameter of the protrusion support.

  When ink is ejected, ink is supplied from the common liquid chamber 6 to each nozzle channel 10 by the amount of ink used (see FIG. 3). However, if the diameter of the protruding column 7 is too large, the protruding column impedes the flow of ink as shown in FIG. 7, and sufficient ink cannot be supplied to the nozzle channel 10. In particular, when the ejection frequency is high, the heater 11 is heated before the ink is filled in the nozzle flow path 10, so that the ink is not ejected, resulting in the occurrence of image defects and heater destruction. Therefore, it is necessary to define the cross-sectional shape of the protruding column 7 that does not hinder the ink supply.

  FIG. 8 is a view for explaining the cross-sectional shape of the projection support 7.

  Taking one nozzle as an example, a flux corresponding to the interval L3 between the adjacent movable valves 3 is required to cause ink to flow quickly into the nozzle flow path 10 (see FIG. 3). When the flux is larger than this, the ink for the region L3 is supplied to the nozzle channel 10 and the remaining ink is discharged or circulated. On the other hand, when the flow rate is low, the ink in the nozzle channel 10 cannot be filled, or it takes time to sufficiently fill the ink in the discharge nozzle 12.

  If the ejection frequency is low, ink filling may be in time, but if the ejection frequency is high, as described above, the next ejection is performed before the ink consumed by the previous ejection is completed. Therefore, there is a risk that ejection failure may occur. Therefore, in order to realize a high discharge frequency, the cross-sectional diameter L1 of the projection support column 7 needs to be smaller than the thickness L2 of the nozzle partition wall 4 in order to secure a flux corresponding to the region L3.

For this purpose, the following relationship needs to be established among the diameter L1 of the protrusion struts, the total number A of the protrusion struts 7, the thickness L2 of the nozzle partition walls 4, and the total number B of the nozzle partition walls 4.
L1 (1) + L1 (2) + ,,, + L1 (A) <L2 (1) + L2 (2) + ,,, + L (B) (Condition 2)
Then, the cross-sectional dimension and the total number of the projection struts 7 may be set in combination with L4 <C = √ (A ² + B ² ), which is the above-mentioned condition 1.

  In this example, the projection column 7 is circular and the discharge nozzle 12 is rectangular, but the dimensions are defined. The shape of the projection column is “interval smaller than the maximum dimension of the nozzle cross-sectional area (condition 1)” and “adjacent projection column 7 Any shape is sufficient to achieve the object of the present invention as long as the sum of the maximum values of the separation distances is smaller than the sum of the thicknesses L2 of the nozzle partition walls 4 (condition 2). is there.

  The ink jet recording apparatus on which the recording head of the above embodiment is mounted is a head control that controls the heating of the heater 11 so that ink is discharged from the discharge port 1 by heating and foaming the ink in the discharge nozzle 12 according to image data. And a medium transport unit that transports recording paper on which an image is formed by attaching ink.

  According to the above embodiment, when a large load is applied to the movable valve 3 or a large load is applied to the fulcrum portion 15 of the movable valve 3 due to resonance caused by being driven to discharge at a high frequency. Even so, since the protrusion column 7 reliably presses down from above and below to restrict unnecessary movement, the discharge characteristics are not adversely affected, and the durability is not lowered.

  Further, even in a long head having a printing width exceeding 1 inch, the fulcrum portion 15 corresponding to each valve portion (free end) of the movable valve 3 can be pressed. The same effect can be obtained.

  In addition, since the projection struts 7 are arranged at a separation distance smaller than the ejection port 1 so as not to obstruct the nozzle flow path 10, the foreign matter that floats in the head and causes non-ejection is projected without hindering the ink flow. It is also possible to trap between parts.

FIG. 2 is a perspective view illustrating a configuration in the vicinity of a discharge nozzle in an ink jet recording head according to a preferred embodiment to which the present invention is applied. FIG. 2 is a top view of the vicinity of an ejection port in the ink jet recording head of FIG. 1. FIG. 2 is a side sectional view in the vicinity of an ejection port in the ink jet recording head of FIG. 1. It is a figure explaining the dimensional relationship between a movable valve and a projection support | pillar. It is a figure explaining the dimensional relationship between a movable valve and a projection support | pillar. It is a figure explaining the ease of the flow of the ink by the difference in the diameter of a protrusion support | pillar. It is a figure explaining the ease of the flow of the ink by the difference in the diameter of a protrusion support | pillar. It is a figure explaining the cross-sectional shape of the protrusion support | pillar 7. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Discharge port 2 Heater board 3 Movable valve 4 Nozzle partition 5 Nozzle top plate 6 Common liquid chamber 7 Protrusion support | pillar 8 Valve base 10 Nozzle flow path 11 Heater 12 Discharge nozzle 13 Nozzle bank 14 Free end 15 Support point 16 Support member 17 Top plate member

Claims (6)

An ink jet recording head having a plurality of ink discharge ports for discharging ink and a nozzle portion communicating with the ink discharge port,
Provided in the nozzle portion is a movable valve having a free end that is displaced as the ink is foamed, and a heater portion that is disposed near the discharge port and heats and foams the ink.
A plurality of protrusions spaced apart from each other at a predetermined interval are provided at a fulcrum part opposite to the free end of the movable valve, and the protrusions are provided with a heater substrate on which the heater part is formed, and a top plate part facing the heater part. An ink jet recording head characterized by being sandwiched between.   The inkjet recording head according to claim 1, wherein a maximum value of a separation distance between adjacent protrusions is shorter than a maximum linear distance in a discharge port cross section.   The inkjet recording head according to claim 2, wherein the maximum value of the separation distance between the adjacent protrusions is shorter than the diagonal length of the discharge port cross section.   The inkjet recording head according to any one of claims 1 to 3, wherein a plurality of the protrusions are provided for one nozzle part.   5. The inkjet recording according to claim 1, wherein the sum of the maximum distances of the cross sections of the protrusions parallel to the top plate surface is smaller than the sum of the thicknesses of the side walls of the nozzles. head. An ink jet recording head according to any one of claims 1 to 5,
A head control unit that controls the heater unit to eject ink from the ink ejection port by heating and foaming ink in the nozzle unit according to image data;
An ink jet recording apparatus comprising: a medium transport unit that transports a recording medium to which the ink is attached.

Images