JP2004122775A5 - - Google Patents

Description

Ultra-fine droplet ejection device

  The present invention relates to an extremely small droplet ejecting apparatus such as an ink jet printer capable of ejecting extremely small droplets.

  In an ink jet printer, it is desired to make ink droplets ejected from a head as small as possible in order to improve print image quality. From such a point of view, a fine ink droplet of about 2 pl can be ejected by devising a control pulse waveform of an actuator that applies ejection energy to ink or by reducing the nozzle diameter.

  However, in recent years, in order to realize high-definition and high-definition printing, it has become necessary to eject very fine ink droplets smaller than 2 pl. However, it is difficult to make the ink droplets smaller by using the above-described method of controlling the pulse waveform and the method of reducing the nozzle diameter.

  As a technique for miniaturizing ink droplets by a method different from that described above, main dots (main ink droplets) and satellite dots (satellite ink droplets) ejected from the nozzle due to a single pressure fluctuation A technique is known in which the control pulse waveform is adjusted and the distance between the nozzle and the printing medium is adjusted so that the landing positions of these two ink droplets are shifted from each other (see Patent Document 1). ). According to this technique, the main ink droplets can be miniaturized and the satellite ink droplets can be enlarged to form printing dots different from the main ink droplets.

Japanese Patent Laid-Open No. 7-285222 (FIG. 1)

  However, in order to print a very high-definition image having, for example, photographic quality, it is necessary to eject ink droplets that are even smaller than those obtained by the above technique. In addition, in an inkjet printer, in addition to a request for ejecting minute ink droplets, there is also a request for ejecting a conductive paste to print an extremely fine electric circuit pattern on a substrate.

  An object of the present invention is to provide an ultrafine droplet ejecting apparatus that can eject ultrafine droplets.

  According to an aspect of the present invention, a first droplet capable of ejecting a main droplet having a first flight trajectory and ejecting a satellite droplet having a smaller volume than the main droplet as the main droplet is ejected. Ejected from the droplet ejecting unit, the second droplet ejecting unit capable of ejecting the droplet having the second flight trajectory intersecting the first flight trajectory, the main droplet, and the second droplet ejecting unit. So that the flying trajectory of the united droplet that the two droplets collide with each other is different from the first flying trajectory of the main droplet, and so that the satellite droplet lands on the printing medium. There is provided an extremely small droplet ejecting apparatus that includes a control unit that controls the first and second droplet ejecting units and that forms dots on a printing medium.

  According to the above configuration, the main droplet ejected from the first droplet ejecting unit and the droplet ejected from the second droplet ejecting unit collide with each other, and the flight trajectory of the combined droplet is the main. As a result of being different from the flight trajectory of the liquid droplets, only extremely small satellite liquid droplets having a volume of, for example, 0.002 pl to 0.5 pl ejected from the first liquid droplet ejecting section are landed on the printing medium. be able to. Therefore, the ink is ejected to print a very high-definition image, the conductive paste is ejected to print an extremely fine electric circuit pattern, or the organic light emitter is ejected to produce an organic electroluminescence display (OELD). ) And other high-definition display devices can be created.

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

  As shown in FIG. 1, the inkjet printer 1 according to the present embodiment includes a platen roller 40 as a conveying unit that conveys a sheet 41 that is a printing medium, and a sheet 41 set on the platen roller 40. An inkjet head 10 that ejects ink and a control unit 20 that controls the operation of each unit in the inkjet printer 1 such as the inkjet head 10 are included.

  The platen roller 40 is rotatably attached to the frame 43 by a shaft 42 and is driven to rotate by a motor 44. The paper 41 is fed from a paper feed cassette (not shown) provided on the side of the ink jet printer 1, transported at a constant speed by the platen roller 40, and predetermined printing is performed by ink ejected from the ink jet head 10. Is then discharged.

  In FIG. 1, detailed illustration of the paper feed mechanism and paper discharge mechanism for the paper 41 is omitted. In addition, the inkjet printer 1 depicted in FIG. 1 is a monochrome printer and includes only one inkjet head 10, but when performing color printing, at least four inkjet heads of yellow, magenta, cyan, and black are used. 10 are arranged in parallel.

  As can be seen from FIG. 1, in the present embodiment, the inkjet head 10 is a line head extending perpendicularly to the conveyance direction of the paper 41, and is fixedly installed on the frame 43.

  The ink-jet head 10 has two flat ink ejecting portions, a first ink ejecting portion 100 and a second ink ejecting portion 200, both extending in a line in one direction. These two ink ejecting units 100 and 200 are connected and integrated so as to form an angle of 135 ° along one end in the width direction (see FIG. 3). From both connecting portions, the base 11 extends in a direction perpendicular to the first ink ejecting portion 100.

  The ink ejection surface of the first ink ejection unit 100 in which a large number of nozzles 109 (see FIG. 2) are formed in a line along the longitudinal direction is opposed to the conveyance surface of the paper 41 by the platen roller 40 in parallel. Therefore, the ink droplets ejected from each nozzle 109 formed in the first ink ejecting unit 100 based on the control of the control unit 20 fly in a trajectory substantially perpendicular to the paper 41. Note that, as will be described later, the first ink ejecting unit 100 generates a main droplet having a relatively large diameter (for example, a diameter of about 4 to 25 μm) and a satellite droplet having a smaller volume by one ejection signal. (For example, about 1.6 to 10 μm in diameter) is controlled by the control unit 20.

For example, when the nozzle diameter is approximately 20 μm, the diameter of the main droplet is 25 μm and the volume is 8 pl, the diameter of the satellite droplet is 10 μm and the volume is 0.5 pl, and when the nozzle diameter is approximately 3.5 μm, the diameter of the main droplet is The diameter of the satellite droplet is 1.6 μm and the volume is 0.002 pl. At this time, the ejection speed of the main droplet is about 9 m / sec, and the ejection speed of the satellite droplet is about 5.5 m / sec.

  On the other hand, the ink ejection surface of the second ink ejection unit 200 in which a large number of nozzles 209 (see FIG. 3) are formed in a line along the longitudinal direction forms an angle of 45 ° with the conveyance surface of the paper 41 by the platen roller 40. ing. The flying trajectory of the ink droplet ejected from the second ink ejecting unit 200 at an appropriate ejecting speed is the flight of the main droplet ejected from the first ink ejecting unit 100 before reaching the transport surface of the paper 41. Crosses the orbit. Accordingly, the ink droplets ejected from the second ink ejecting unit 200 are ejected from the first ink ejecting unit 100 when the ejection speed and the ejection timing are appropriately adjusted based on the control of the control unit 20. Collide with the main droplet.

  In addition, the axis of the nozzle 109 in the first ink ejecting unit 100 (the direction in which the droplets are ejected from the nozzle 109) and the axis of the nozzle 209 in the second ink ejecting unit 200 (the droplets from the nozzle 209) (Injection direction) are arranged at an angle to each other. Further, the axis of the nozzle 109 in the first ink ejection unit 100 is perpendicular to the paper 41, while the axis of the nozzle 209 in the second ink ejection unit 200 is inclined with respect to the paper 41.

  The control unit 20 controls the operation of each unit in the inkjet printer 1 such as the motor 44 and the inkjet head 10. In particular, in the present embodiment, the control unit 20 controls the ink ejection timing and the ink ejection speed from the first ink ejection unit 100 and the second ink ejection unit 200, respectively, so that the first ink ejection unit. A single ejection signal (meaning a drive pulse corresponding to one dot on the paper 41) given to 100 causes satellite droplets of a smaller volume to be ejected along with the ejection of the main droplet, and the first Only one droplet is ejected by one ejection signal given to the second ink ejecting unit 200, and the main droplet ejected from the first ink ejecting unit 100 and the second ink ejecting unit 200 are ejected. The flying ink trajectory of the combined ink droplet collided with the combined ink droplet is made different from the flying trajectory of the main droplet. The ink ejection speed can be controlled by adjusting at least one of the pulse height, the number of pulses, and the pulse width of the ejection signal.

  In order to eject main droplets and satellite droplets from the first ink ejecting unit 100 with one ejection signal, in many cases, the ink ejection speed may be set within a relatively large suitable range. As an example, the range may be about 5 m / sec to 15 m / sec. Further, in order to eject only one droplet from the second ink ejection unit 200 with one ejection signal, in many cases, the ink ejection speed may be set within a relatively small appropriate range. The range may be about 5 m / sec or less as an example. Note that the appropriate ink ejection speed range varies depending on the physical properties of the liquid to be ejected.

  In the ink jet printer 1 according to the present embodiment, the combined ink droplets on the flight trajectory of the main droplet ejected from the first ink ejecting unit 100 slightly deviate from the trajectory of the main droplet until reaching the transport surface of the paper 41. The ink catch portion 30 is disposed (see FIGS. 1 and 4A to 4D). On the surface of the ink catch portion 30, a member such as a cloth or a sponge that can absorb and hold ink while preventing scattering of ink is disposed. As a result, the combined ink droplets are received by the ink catch portion 30 before reaching the transport surface of the paper 41, so that the ink can be prevented from landing on the paper 41. As shown in FIG. 1, a flow path 31 is formed at the bottom of the ink catch portion 30, which allows the received combined ink droplets to flow outside the ink catch portion 30 and be discarded.

  Next, the detailed structure of the inkjet head 10 including the first ink ejecting unit 100 and the second ink ejecting unit 200 will be described with further reference to FIGS. In FIG. 3, illustration of the vicinity of the connecting portion between the first ink ejecting unit 100 and the second ink ejecting unit 200 and the base 11 is omitted.

  As shown in FIGS. 2 and 3, the first ink ejecting unit 100 is driven by a drive pulse signal (selectively taking either a ground potential or a positive predetermined potential) generated by a drive circuit (not shown). The actuator unit 106 and the flow path unit 107 forming the ink flow path are stacked. The actuator unit 106 is a bimorph type piezoelectric actuator. The actuator unit 106 and the flow path unit 107 are bonded together by an epoxy thermosetting adhesive. A flexible wiring board (not shown) or the like is joined to the upper surface of the actuator unit 106 in order to apply a drive pulse signal generated by a drive circuit (not shown).

  The flow path unit 107 includes three thin plate plates (cavity plate 107a, spacer plate 107b, manifold plate 107c) made of a metal material, and a nozzle plate made of a synthetic resin such as polyimide having a nozzle 109 for ejecting ink. 107d is laminated. The uppermost cavity plate 107 a is in contact with the actuator unit 106.

  On the surface of the cavity plate 107a, a plurality of pressure chambers 110 for containing ink selectively ejected by the operation of the actuator unit 106 are arranged in the longitudinal direction of the ink ejecting unit 100 (left and right in FIG. 2, and on the paper in FIG. 3). (In a vertical direction). The plurality of pressure chambers 110 are separated from each other by a partition wall 110a.

  The spacer plate 107b is formed with a communication hole 111 that allows one end of the pressure chamber 110 to communicate with the nozzle 109, and a communication hole 112 (see FIG. 3) that allows the other end of the pressure chamber 110 to communicate with a manifold channel 115 described later. Has been.

  The manifold plate 107 c is formed with a communication hole 113 that allows one end of the pressure chamber 110 to communicate with the nozzle 109. Furthermore, a manifold channel 115 that supplies ink to the pressure chambers 110 is formed in the manifold plate 107 c so as to be long in the column direction below the column formed by the plurality of pressure chambers 110. One end of the manifold channel 115 is connected to an ink supply source (not shown).

  In this way, an ink flow path is formed from the manifold flow path 115 to the nozzle 109 via the communication hole 112, the pressure chamber 110, the communication hole 111, and the communication hole 113.

  In the actuator unit 106, six piezoelectric ceramic plates 106a to 106f made of a ceramic material of lead zirconate titanate (PZT) are laminated. Between the piezoelectric ceramic plate 106b and the piezoelectric ceramic plate 106c, and between the piezoelectric ceramic plate 106d and the piezoelectric ceramic plate 106e, the common electrodes 101 and 103 are within a range corresponding to the pressure chamber 110 of the flow path unit 107, respectively. (See FIG. 3). The common electrodes 101 and 103 may be disposed over a wide range covering almost the entire range of each piezoelectric ceramic plate.

  On the other hand, the individual electrodes 102 and 104 correspond to the pressure chamber 110 of the flow path unit 107 between the piezoelectric ceramic plate 106c and the piezoelectric ceramic plate 106d and between the piezoelectric ceramic plate 106e and the piezoelectric ceramic plate 106f, respectively. They are arranged only within the range (see FIG. 3).

  As shown in FIG. 2, the common electrodes 101 and 103 are always held at the ground potential. On the other hand, a drive pulse signal is given to the individual electrodes 102 and 104. The sandwiched regions of the piezoelectric ceramic plates 106c to 106e sandwiched between the common electrodes 101 and 103 and the individual electrodes 102 and 104 become active portions that are polarized in the stacking direction when an electric field is applied in advance by these electrodes. Yes. Therefore, when the potentials of the individual electrodes 102 and 104 become a predetermined positive potential, the active portions of the piezoelectric ceramic plates 106c to 106e are applied with an electric field and tend to extend in the stacking direction. However, since such a phenomenon does not appear in the piezoelectric ceramic plates 106a and 106b, the portion corresponding to the active portion of the actuator unit 106 swells to protrude toward the pressure chamber 110 as a whole.

  The left side of the two pressure chambers 110 shown in FIG. 2 is reduced by the volume of the pressure chamber 110 by the actuator unit 106 that is given a positive predetermined potential and extends to the pressure chamber 110 side. A state in which ink is about to be ejected from a nozzle 109 communicating with a pressure chamber 110 is depicted.

  In ejecting ink, “fill before fire” (a voltage is applied to all the individual electrodes 102 and 104 in advance to reduce the volume of all the pressure chambers 110 as shown on the left side of FIG. Only the pressure chamber 110 in which ink is to be ejected releases the voltage of the individual electrodes 102 and 104 and expands the volume as shown on the right side of FIG. 2 to generate a negative pressure wave, and then again the individual electrode 102. , 104 is applied to reduce the volume of the pressure chamber 110, and the positive pressure wave is superimposed so that the negative pressure wave generated previously is synchronized with the positive inversion timing. A method of efficiently applying a discharge pressure to ink using a propagating pressure wave is adopted. As a result, the main droplet and the small volume satellite droplet are ejected from the nozzle 109 by one ejection signal that is a drive pulse corresponding to one dot on the paper 41.

  The second ink ejecting unit 200 also has the same structure as the first ink ejecting unit 100, and is the same as the first ink ejecting unit 100 except that it is controlled so that satellite droplets are not ejected. Operate. Therefore, here, as shown in FIG. 3, the reference numeral of the second ink ejecting unit 200 is changed from “1” to “2” in the three-digit number of the reference numeral of each part of the first ink ejecting unit 100. A detailed description of the second ink ejecting unit 200 will be omitted as being used as a symbol representing each corresponding unit.

  Next, details of the ink ejection operation in the inkjet printer 1 according to the present embodiment will be described with reference to FIGS. 4 (a) to 4 (d). In addition, in each figure of Fig.4 (a)-FIG.4 (d), illustrations other than the nozzle vicinity part of a flow path unit and illustration of an actuator unit are abbreviate | omitted.

  First, as shown in FIG. 4A, the first ink ejecting unit 100 is provided by applying the ejection signal as described above to the actuator unit 106 of the first ink ejecting unit 100 based on the control of the control unit 20. The main droplet 12 (jetting speed of about 5 to 15 m / sec) is ejected from the nozzle 109. In the state shown in FIG. 4A, the main liquid droplet 12 is connected to the nozzle 109 on the rear side, and no satellite liquid droplet is formed yet. On the other hand, by supplying the above-described ejection signal to the actuator unit 206 of the second ink ejection unit 200 based on the control of the control unit 20, the ink droplet 14 (ejection) is ejected from the nozzle 209 of the second ink ejection unit 200. The speed is about 4 m / sec).

  Here, the timing at which the ejection signal is given to the first ink ejection unit 100 and the second ink ejection unit 200 and the ejection speed of the main droplet 12 and the ink droplet 14 are determined by the first ink ejection unit 100. The main ink droplet 12 ejected from the second ink ejecting section 200 collides with the ink droplet 14 and the combined ink droplet is combined so that the flight trajectory of the main droplet 12 is the same. It is decided to be different. Therefore, the timing at which the main droplets are ejected from the first ink ejecting unit 100 and the timing at which the ink droplets are ejected from the second ink ejecting unit 200 may be the same or different.

  A flight trajectory 12 a of the main droplet 12 (and a flight trajectory 13 a of a satellite droplet 13 described later) is a linear trajectory perpendicular to the paper 41. On the other hand, the flying trajectory 14 a of the ink droplet 14 is a linear trajectory that intersects the flying trajectory 12 a of the main droplet 12 obliquely above the ink catch portion 30.

  As shown in FIG. 4B, immediately after the ejection of the main droplet 12, satellite droplets 13 are formed separately from the main droplet 12 in the air. Both the main droplet 12 and the satellite droplet 13 fly according to the flight trajectories 12a and 13a, which are linear trajectories perpendicular to the paper 41.

  Thereafter, the main droplet 12 ejected from the first ink ejecting unit 100 and the ink droplet 14 ejected from the second ink ejecting unit 200 collide with each other. Then, as shown in FIG. 4C, a combined ink droplet 15 in which both are integrated is formed. The flying trajectory 15a of the combined ink droplet 15 is determined by the vector sum of the momentum (the product of volume (mass) and velocity) of the two droplets 12, 14, and the combined direction of the flying trajectories of the two droplets 12, 14 This is a linear trajectory in the direction of traveling toward the ink catch portion 30, which is different from the conventional trajectory 12 a of the main droplet 12. On the other hand, the satellite droplets 13 are not affected by the ink droplets 14 and proceed as they are along the same flight trajectory 13a as before.

  Eventually, as shown in FIG. 4D, the combined ink droplet 15 is received by the ink catch portion 30 without reaching the paper 41, flows through the ink flow path 31 (see FIG. 1), and the ink catch portion 30. Discarded outside. On the other hand, the satellite droplets 13 reach the paper 41 as it is and land.

  Here, referring to FIG. 5A and FIG. 5B, each droplet 12, when the ejection timing of the second ink ejection unit 200 is made earlier than the ejection timing of the first ink ejection unit 100, The relational expression concerning 13 and 14 will be described. FIG. 5A shows a state in which droplets 12, 13, and 14 are ejected from the ink ejecting units 100 and 200 and fly. FIG. 5B is a graph showing drive pulses applied to the first and second ink ejecting units.

  Assuming that the time from when the main droplet 12 is ejected to the intersection A (see FIG. 5A) between the flight trajectory 12a of the main droplet 12 and the flight trajectory 14a of the ink droplet 14 is Tm1, the following equation is obtained. (1) is established. Tm1 = X1 / Sm1 (1) (where X1: distance from the first ink ejecting unit 100 to the intersection A, Sm1: ejection speed of the main droplet 12)

  Similarly, the following expressions (2) and (3) are established for the time Tm2 until the ink droplet 14 reaches the intersection A and the time Ts1 until the satellite droplet 13 reaches the intersection A after being ejected. To do. Tm2 = X2 / Sm2 (2) Ts1 = X1 / Ss1 (3) (where X2: distance from the second ink ejecting section 200 to the intersection A, Sm2: ejecting speed of the ink droplet 14, Ss1: satellite liquid. Spray speed of droplet 13)

  5B, the time difference between the ejection timing T2 of the second ink ejection unit 200 and the ejection timing T1 of the first ink ejection unit 100 is D. Further, assuming that the driving voltage of the first ink ejecting unit 100 is V1, and the driving voltage of the second ink ejecting unit 200 is V2, V1> V2.

  Here, the following equation (4) is established when the main droplet 12 and the ink droplet 14 collide, and the following equation (5) is established when the satellite droplet 13 does not collide with the ink droplet 14. It should be noted that the left side and the right side of Equation (4) are not necessarily equal and need only be approximately equal to the extent that the main droplet 12 and the ink droplet 14 are in contact with each other. Tm1 + D = Tm2 (4) Ts1 + D ≠ Tm2 (5)

  For example, consider the case where X1 = 1.5 mm, X2 = 1.5 mm, V1 = 24 V, Sm1 = 9 m / sec, Ss1 = 5.5 m / sec, V2 = 16 V, Sm2 = 5 m / sec, and D = 143 μsec. View. In this case, according to the equation (2), the ink droplet 14 from the second ink ejecting unit 200 reaches the intersection A 300 μsec (Tm2) after being ejected. On the other hand, according to the equation (1), the main droplet 12 from the first ink ejecting unit 100 is ejected 143 μsec (D) after the ink droplet 14 is ejected and further 167 μsec (Tm1), that is, the main liquid. The droplet 12 reaches the intersection A 300 μsec (Tm1 + D) after the ink droplet 14 is ejected. At this time, Expression (4) is established, and the main droplet 12 and the ink droplet 14 collide. Further, according to the expression (3), the satellite droplet 13 is ejected 143 μsec (D) after the ink droplet 14 is ejected and further 273 μsec (Ts1), that is, the satellite droplet 13 is ejected by the ink droplet 14. 416 μsec (Ts1 + D) after reaching the intersection, the intersection A is reached. At this time, Expression (5) is established, and the satellite droplet 13 does not collide with the ink droplet 14.

  The pulse width of the drive pulse as shown in FIG. 5B is usually the time AL (Acoustic Length) required for the pressure wave to propagate from the manifold channels 115 and 215 shown in FIG. 3 to the nozzles 109 and 209. Set to be equal to the value of. The value of AL is determined by the head design and is, for example, 4 to 12 μsec. When the pulse width is set equal to the AL value, the injection energy efficiency is maximized, and when the pulse width is set to a value far from the AL value, the injection speed is lowered.

  It is also possible to adjust the time Tm1, Tm2, and Ts1 until the droplet A is reached by changing the ejection speed of each droplet according to the peak values of the drive voltages V1 and V2 as shown in FIG. is there.

  4A to 4D and FIG. 5A show the relative movement of each droplet 12, 13, and 14 with respect to the inkjet head 10 including the ink ejecting units 100 and 200. FIG. .

  Thus, according to the ink jet printer 1 of the present embodiment, the main liquid droplet 12 ejected from the first ink ejecting unit 100 and the ink liquid droplet 14 ejected from the second ink ejecting unit 200 collide. Thus, the flying trajectory 15a of the combined ink droplet 15 in which both are combined is different from the flying trajectory 12a of the main droplet 12. As a result, only the satellite droplets 13 ejected from the first ink ejecting unit 100 can be landed on the paper 41 that is the printing medium. Therefore, high-definition ink jet recording using satellite droplets 13 which are ultrafine droplets having a volume of 0.002 pl to 0.5 pl is possible.

  Further, since the ink catch unit 30 receives the combined ink droplet 15 above the conveyance surface of the paper 41, the combined ink droplet 15 does not land on the conveyance surface of the paper 41. As a result, the print contents on the paper 41 are not disturbed by the combined ink droplets 15 and the image quality is not deteriorated.

  Further, since a small volume of liquid droplets other than the ink droplet 14 is not ejected by the single ejection signal from the second ink ejecting unit 200, the small volume of liquid droplets and the first ink ejecting unit 100 are ejected. There is no possibility of collision with the satellite droplets 13, and control of the first and second ink ejecting units 100 and 200 is facilitated.

  In addition, since both the first and second ink ejecting units 100 and 200 are fixedly installed with respect to the frame 43, errors in the flight trajectories 12a to 15a of the ink droplets 12 to 15 ejected therefrom are unlikely to occur. Become. As a result, the main liquid droplet 12 ejected from the first ink ejecting section 100 and the ink liquid droplet 14 ejected from the second ink ejecting section 200 can reliably collide.

  In addition, since the first and second ink ejecting units 100 and 200 are integrally formed as one ink jet head 10, the ink jet printer 1 is very compact.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various design changes can be made as long as they are described in the claims. For example, in the above embodiment, the first and second ink ejecting units 100 and 200 are integrally formed as one ink jet head 10, but the ink jet head having the first ink ejecting unit 100, Two inkjet heads including the inkjet head having the two ink ejecting units 200 may be provided.

  Further, the angle formed between the ink ejection surfaces in the two ink ejection units 100 and 200 and the angle between the ink ejection surface and the paper 41 in the second ink ejection unit 200 are not limited to 135 ° and 45 °, respectively. , May vary.

  Further, the distances X1 and X2 from the ink ejecting units 100 and 200 to the intersection A shown in FIG. 5A can be changed as appropriate.

  Further, the material of the ink ejected from the second ink ejecting unit 200 may or may not be the same as the ink ejected from the first ink ejecting unit 100.

  Further, the structures of the first and second ink ejecting units 100 and 200 are not limited to those described above, and can be changed to various forms depending on the application.

  For example, an inkjet head 700 shown in FIGS. 6A and 6B can be considered as a modification of the inkjet head 10 described above. In the ink jet head 700, a first ink ejecting section 500 and a second ink ejecting section 600 in which axes of nozzles 509 and 609 (shown by a one-dot chain line in the drawing) intersect with each other are paired. The nozzles 509 and 609 are formed on the lowermost nozzle plate of the flow path unit 707 so as to be inclined with respect to each other. Further, a metal diaphragm 706 is disposed on the uppermost plate in which the pressure chambers 510 and 610 are formed, and a thickness is provided at a position facing the pressure chambers 510 and 610 on the diaphragm 706. Piezoelectric sheets 506 and 606 polarized in the direction are arranged, respectively. Here, when the vibration plate 706 is set to the ground potential and a potential higher than the ground potential is applied to the individual electrodes 501 and 601 on the piezoelectric sheets 506 and 606, the piezoelectric sheets 506 and 606 extend in the thickness direction and the piezoelectric lateral effect is obtained. Shrink in the surface direction. The situation at this time is shown in an enlarged view in FIG. 6B. From this figure, the individual electrodes 501 and 601 and the diaphragm 706 are deformed (unimorph deformation) so as to protrude toward the pressure chambers 510 and 610. I understand. That is, a unimorph type drive mechanism is realized.

  Further, FIG. 6 (a) shows communication holes 512 and 612 provided at the other ends of the pressure chambers 510 and 610, and a manifold flow communicated with the pressure chambers 510 and 610 via the communication holes 512 and 612. A road 715 is drawn with a dotted line.

  Also, as shown in FIGS. 6A and 6B, an ink catch portion 730 is disposed between the nozzles 509 and 609 and the paper 41. Therefore, the main droplet and the satellite droplet are ejected from the nozzle 509, and only a single ink droplet is ejected from the nozzle 609. The main droplet from the nozzle 509 and the ink from the nozzle 609 are the same as in the above-described embodiment. The combined liquid droplet 815 that has collided with the liquid droplet is received by the ink catch portion 730. Only the satellite droplets 813 from the nozzles 509 land on the paper 41.

  The actuator is not limited to the bimorph type or the unimorph type, and may have various configurations.

  In addition to the ink droplets 14, satellite droplets having a smaller volume than the ink droplets 14 may be ejected following the ink droplets 14 by a single ejection signal from the second ink ejecting unit 200. According to this, the ink droplet 14 can be ejected from the second ink ejecting unit 200 at a relatively high speed, and as a result, the flight trajectory of the combined ink droplet 15 is significantly different from the flight trajectory of the main droplet 12. Can be made. However, in this case, it is preferable to perform control so that the small-volume satellite droplets ejected from the second ink ejecting unit 200 do not collide with the satellite droplets 13 ejected from the first ink ejecting unit 100. For example, it is preferable to establish the following expression (6) in addition to the above expressions (4) and (5). Ts1 + D ≠ Ts2 (6) (where Ts2: time until satellite droplets ejected from the second ink ejecting section 200 reach the intersection A shown in FIG. 5A)

  Alternatively, the combined ink droplets formed by the collision of the satellite droplets 13 ejected from the first ink ejecting unit 100 and the satellite droplets ejected from the second ink ejecting unit 200 are used as printing dots on the paper 41. You may land on top. In this case, the combined ink droplet 15 of the main droplet 12 and the ink droplet 14 is moved along the flight trajectory so that the combined ink droplet of each satellite droplet is landed on the paper 41 (see FIG. 4C). ) Must be different from the flight trajectory. The flying trajectory of the combined ink droplets of each satellite droplet is determined by the vector sum of the momentum (product of volume (mass) and velocity) of the two satellite droplets.

  For example, the ejection speed of the main droplet 12 is 9 m / sec / volume 1 pl, the ejection speed of the satellite droplet 13 ejected from the first ink ejection unit 100 is 5.5 m / sec / volume 0.06 pl, and the second ink ejection. The ejection speed of the larger ink droplet (main droplet) 14 ejected from the section 200 is 7 m / sec and the volume is 1 pl, and the ejection speed of the satellite droplet 3 ejected from the second ink ejection section 200 is 4.7 m / second. In the case of sec and volume 0.06 pl, if D = 48 μsec, the formula Ts1 + D = Ts2 is established, and the larger main droplets and the smaller satellite droplets are merged, and the flight trajectory of each is calculated. Can be different.

  Further, the inkjet head 10 may be a serial head instead of a line head, and in this case, the inkjet head 10 may be controlled to reciprocate in a direction orthogonal to the paper transport direction. In this way, it is possible to print on a large size paper with a shorter head. Even in this case, when viewed in a coordinate system in which the inkjet head 10 including the ink ejecting units 100 and 200 is fixed, FIGS. 4A to 4D and FIG. 5A apply, and the main droplet 12 and the satellite liquid are applied. Since the droplet 13 has the same ejection direction, the flight trajectory is also the same. However, when viewed from the outside of the head 10, the flight trajectory is determined by the vector sum of the ejection speed and the moving speed of the head, so that the main droplet 12 and the satellite droplet 13 have different flight trajectories. .

  In addition, in the micro droplet ejecting apparatus configured in the same manner as the ink jet printer described in the above-described embodiment, an extremely fine electric circuit pattern can be printed by using a conductive paste as the ejecting medium. In addition, in the micro droplet ejecting apparatus configured in the same manner as the ink jet printer described in the above-described embodiment, an organic light emitter is used as an ejecting medium, so that a high-definition display device such as an organic electroluminescence display (OELD) is used. Can also be created. In addition, the micro droplet ejecting apparatus configured in the same manner as the ink jet printer described in the above-described embodiment can be used in a very wide range as long as it is used for forming micro dots on a printing medium.

1 is a perspective view showing a schematic configuration of an ink jet printer that is an ultrafine droplet ejecting apparatus according to an embodiment of the present invention. It is the fragmentary sectional view which cut | disconnected the 1st ink ejection part of the inkjet head contained in the inkjet printer shown in FIG. 1 along the longitudinal direction. It is sectional drawing which cut | disconnected the inkjet head contained in the inkjet printer shown in FIG. 1 along the width direction. FIG. 4 is a schematic diagram sequentially illustrating the state of ink droplets ejected from an inkjet head, corresponding to FIG. 3. FIG. 9 is an explanatory diagram for explaining a relational expression relating to each droplet when the ejection timing of the second ink ejection unit is made earlier than the ejection timing of the first ink ejection unit. It is a graph which shows the drive pulse provided to the 1st and 2nd ink ejection part. It is a fragmentary sectional perspective view which shows the modification of the inkjet head by this invention. It is the elements on larger scale of Fig.6 (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 10 Inkjet head 11 Base 12 Main droplet 12a Flight trajectory of main droplet 13 Satellite droplet 13a Flight trajectory of satellite droplet 14 Ink droplet 14a Flight trajectory of ink droplet 15 Combined ink droplet 15a Combined ink liquid Droplet trajectory 20 Control unit 30 Ink catch unit 40 Platen roller 41 Paper 100 First ink ejecting unit 106 Actuator unit 107 Flow path unit 109, 209 Nozzle 110 Pressure chamber 200 Second ink ejecting unit

Claims (20)

A first droplet ejecting unit capable of ejecting a main droplet having a first flight trajectory and ejecting a satellite droplet having a volume smaller than that of the main droplet along with the ejection of the main droplet; ,
A second liquid droplet ejecting unit capable of ejecting liquid droplets having a second flight trajectory that intersects the first flight trajectory;
The flight trajectory of the combined liquid droplet in which the main liquid droplet collides with the liquid droplet ejected from the second liquid droplet ejecting unit is different from the first flight trajectory of the main liquid droplet. And a control means for controlling the first and second liquid droplet ejecting units so that the satellite liquid droplets land on the print medium. An ultra-fine droplet ejecting device.   2. The control unit according to claim 1, wherein the control unit controls an ejection timing and an ejection speed of the main droplet, the satellite droplet, and a droplet ejected from the second droplet ejecting unit. Ultra-fine droplet ejector.   3. The micro droplet according to claim 1, wherein the satellite droplet has a flight trajectory that is substantially the same as the first flight trajectory relative to the first droplet ejecting unit. 4. Injection device.   The main droplet and the satellite droplet are ejected at a first ejection timing, and the droplet from the second droplet ejection section is ejected at a second ejection timing different from the first ejection timing. The ultrafine droplet ejecting device according to claim 1, wherein   The second ejection timing is earlier than the first ejection timing, and when the time difference is D, when the main droplet and the droplet ejected from the second droplet ejecting unit collide, The ultrafine liquid droplet ejecting apparatus according to claim 4, wherein Tm1 + D = Tm2 (where Tm1 = X1 / Sm1, Tm2 = X2 / Sm2Tm1: Time Tm2 from when the main droplet is ejected until the intersection of the first flight trajectory and the second flight trajectory is reached: Time X1 until the liquid droplet ejected from the second liquid droplet ejecting section reaches the intersection X1: Distance X2 from the first liquid droplet ejecting section to the intersection: From the second liquid droplet ejecting section Distance to intersection Sm1: ejection speed of main droplet Sm2: ejection speed of droplet ejected from second droplet ejecting section   6. The extremely small amount according to claim 5, wherein when the satellite liquid droplets land on the printing medium without colliding with the liquid droplets ejected from the second liquid droplet ejecting section, Droplet ejector. Ts1 + D ≠ Tm2 (where Ts1 = X1 / Ss1Ts1: time from when the satellite droplet is ejected until the intersection is reached Ss1: ejection velocity of the satellite droplet)   The control unit applies the first and second drive signals to the first and second droplet ejecting units, respectively, so that the main droplet and the satellite droplet are output from the first droplet ejecting unit. The micro droplet ejecting apparatus according to claim 2, wherein the droplets are ejected from the second droplet ejecting unit.   The first drive signal includes one drive pulse, the second drive signal includes one drive pulse, and the drive pulse included in the first drive signal is included in the second drive signal. The micro droplet ejecting apparatus according to claim 7, wherein a crest value is higher than that of the driving pulse.   The ejection speed of the main droplet and the satellite droplet is substantially 5 to 15 m / sec, and the ejection speed of the droplet ejected from the second ejection section is substantially 5 m / sec or less. The ultrafine liquid droplet ejecting apparatus according to claim 2, wherein The micro droplet ejecting apparatus according to claim 1, wherein the volume of the satellite droplet is substantially 0.002 to 0.5 pl.   A droplet catch unit is disposed between the first and second droplet ejecting units and the print medium, and further includes a droplet catch unit for receiving the merged droplets before the merged droplets land on the print medium. The ultrafine droplet ejecting apparatus according to claim 1, wherein   The ultrafine droplet ejecting apparatus according to claim 11, further comprising a discharge path for discharging the combined droplets received by the droplet catching portion through the droplets.   The control unit controls the second droplet ejecting unit so that an additional droplet having a smaller volume than the droplet is not ejected along with ejection of the droplet from the second droplet ejecting unit. The ultrafine droplet ejecting device according to claim 1, wherein:   The control means causes an additional droplet having a smaller volume than the droplet to be ejected in accordance with the ejection of the droplet from the second droplet ejecting unit, and the additional droplet is the satellite liquid. 13. The micro droplet ejection according to claim 1, wherein the first droplet ejecting unit and the second droplet ejecting unit are controlled so as not to collide with a droplet. apparatus.   The ultra-small droplet ejecting apparatus according to claim 1, wherein both the first and second droplet ejecting units are fixedly installed.   The first and second droplet ejecting sections each form a plurality of nozzles, and the nozzle axes of the first and second droplet ejecting sections are arranged at an angle to each other. The ultrafine droplet ejecting apparatus according to claim 1, wherein the apparatus is characterized in that:   One of the axis of the nozzle in the first liquid droplet ejecting section and the axis of the nozzle in the second liquid droplet ejecting section is perpendicular to the print medium and the other is relative to the print medium. The ultrafine droplet ejecting apparatus according to claim 16, wherein the apparatus is inclined. Each of the first and second droplet ejecting units is
A plurality of pressure chambers containing liquid, and a flow path unit in which nozzles communicating with the pressure chambers are formed;
The micro droplet ejecting apparatus according to claim 1, further comprising an actuator that varies a pressure of the plurality of pressure chambers.   The ultrafine droplet ejecting apparatus according to claim 18, wherein the first and second droplet ejecting units are integrally formed as one droplet ejecting head. A first droplet ejecting section having a nozzle, the axis of the nozzle extending in a first direction;
A second liquid droplet ejecting section, in which a nozzle is formed and extending in a second direction in which an axis of the nozzle intersects the first direction;
Control means for ejecting droplets from the first and second droplet ejecting units by applying a drive signal to the first and second droplet ejecting units;
Before placing a part of the droplets, which are disposed between the first and second droplet ejecting units and the printing medium and ejected from the first and second droplet ejecting units, on the printing medium. And a droplet catching part for receiving
The control unit ejects a main droplet and a satellite droplet having a smaller volume than the main droplet from the first droplet ejecting unit, and ejects the main droplet and the second droplet ejecting unit. The first and second liquid droplets so that the combined liquid droplets collide with the formed liquid droplets are directed to the liquid droplet catching section, and the satellite liquid droplets land on the printing medium. An ultra-fine droplet ejecting apparatus that controls an ejecting unit.