JP2010110664A - Pattern forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pattern forming device which suppresses contamination of a drawing surface due to satellite droplets, with respect to the pattern forming device for irradiating flying droplets with light to dry the flying droplets. <P>SOLUTION: A driving signal supplied to each piezoelectric element is set so that the speed of a cutting point in the nozzle side of the satellite droplets in the cutting of the satellite droplets from the nozzle is made higher than the speed of main droplets to unite the main droplet and the satellite droplets with each other after the main droplets and the satellite droplet fly only by an isolated flight space. That is, the rate of the change of a fifth wave shape part 75 regulating the speed of the cutting point of the satellite droplet in the nozzle side is made larger than the rate of change of a third wave shape part 73 regulating the main droplet. The satellite droplet with the discharge of the main droplet is united with the preceding main droplet and deposited on the drawing surface. Thus the contamination of the drawing surface due to the satellite droplets is suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pattern forming apparatus for irradiating a droplet in flight with laser light.

  Multi-layer substrates made of low temperature co-fired ceramics (LTCC) have excellent high frequency characteristics and high heat resistance, and are therefore widely used for high frequency module substrates, IC package substrates, and the like. Such LTCC multilayer substrates are generally manufactured by laminating green sheets on which circuit patterns are drawn using metal ink and firing them together.

In the step of drawing the circuit pattern, a so-called ink jet method has been proposed in which metal ink is ejected as fine droplets in order to increase the density of the circuit pattern (for example, Patent Document 1). In the ink jet method, a droplet with a capacity of several to several tens of picoliters is ejected from a nozzle provided in an ejection head, and the ejection position of such a droplet is changed according to the shape of the circuit pattern. Simple circuit patterns can be drawn.
JP 2005-57139 A

  By the way, in order to form a high-definition pattern using the ink jet method, it is preferable to reduce the landing diameter by quickly drying the discharged droplets and suppressing wetting spread on the substrate. As one method, a method of irradiating a droplet in flight ejected from an ejection head with laser light to promote drying of the droplet during flight has been studied. When evaporating a desired amount of evaporation component using such a method, the minimum energy required for the laser beam can be roughly specified according to the desired amount. An embodiment in which the minimum energy is given to the liquid droplets therein is preferable.

  On the other hand, in the ink jet method in which droplets are ejected by vibrating a meniscus formed on a nozzle, droplets ejected from the vibrating meniscus are generally generated in a manner that draws a tail. In the droplet discharged in this way, the tip of the droplet is cut from the rear end by the dynamic surface tension of the liquid material acting on the rear end corresponding to the spherical tip or tail, A main droplet is generated in advance by the tip of the droplet. Further, the rear end portion of the droplet is cut from the nozzle, and a minute satellite droplet following the main droplet is generated. When these satellite droplets in the flight process are irradiated with laser light, the satellite droplets, which are smaller in size than the main droplets, are bent due to the light pressure received from the laser light and the reaction force when the evaporation components evaporate. In the end, it will land on a different area from the discharge area and contaminate the drawing surface on the substrate. FIG. 14 is a plan view showing the landing state of the main droplet and satellite droplet landed upon receiving such laser light.

As shown in FIG. 14, for example, in the case of drawing a line pattern by arranging main droplets in one direction, satellite droplets that have been bent in flight are scattered around the main droplets. It will land in shape. In addition to contaminating the entire periphery of the drawing pattern with satellite droplets, especially when forming fine conductive patterns, the satellite droplets land on the position where the pattern should not be formed to make the conductive There is a risk of causing an electrical short circuit between the patterns. In addition, the amount of metal ink disposed in the wiring portion is reduced by the amount of forming satellite droplets, which causes an increase in wiring resistance and disconnection.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to draw with satellite droplets in a pattern forming apparatus that irradiates the flying droplets with laser light to dry the flying droplets. An object of the present invention is to provide a pattern forming apparatus that suppresses surface contamination.

  The pattern forming apparatus of the present invention has a pressure chamber for storing a liquid material containing an evaporation component and a pattern forming material, a pressure generating element that varies the pressure of the pressure chamber, and a nozzle that communicates with the pressure chamber. A laser beam is emitted to a space between the nozzle and the drawing target, a discharge head that discharges the droplets from the nozzle toward the drawing target, a discharge control unit that drives the pressure generating element, A laser irradiation unit that evaporates the evaporation component from the droplets in flight, and forms a pattern with the droplets that have landed on the drawing target, wherein the discharge control unit includes the discharge controller When the satellite droplet is cut from the nozzle, the satellite droplet is cut off on the nozzle side so that the satellite droplet generated along with the discharge of the droplet is united with the droplet in flight. The speed higher than the speed of the droplet.

  When droplets are ejected by vibrating a meniscus that is a gas-liquid interface formed on a nozzle, the droplets ejected from the vibrating meniscus are generally generated in a tail-drawing manner. In the droplet discharged in this way, the tip of the droplet is cut from the rear end by the dynamic surface tension of the liquid material acting on the rear end corresponding to the spherical tip or tail, The main droplet is generated in advance by the tip of the droplet. Further, the rear end portion of the droplet is cut from the nozzle, and satellite droplets following the main droplet are generated. The satellite droplets generated in this manner are elongated in the discharge direction immediately after cutting, but gradually become spherical due to the surface tension and the like. In the case of satellite droplets having a spherical shape, if the velocity distribution is generated when the satellite droplet has an elongated shape, the velocity is stored and the satellite droplet flies. In addition, these droplets in flight are more susceptible to the effects of external forces such as the light pressure from the laser beam and the reaction force accompanying evaporation of evaporation components and the air resistance during flight as the volume of the droplets decreases. It becomes easy. According to this pattern forming apparatus, the satellite droplets are aligned with the main droplets in flight, regardless of whether the satellite droplet volume is relatively small or the main droplet volume is relatively small. As described above, since a speed difference is provided between the main droplet and the satellite droplet, it is possible to suppress contamination of the drawing target object by the satellite droplet.

  In this pattern forming apparatus, the discharge control unit cuts the satellite droplet on the nozzle side so that the droplet and the satellite droplet are united before the droplet and the satellite droplet are boiled. The gist is to perform control to make the dot velocity higher than the droplet velocity.

  In order to suppress bumping of droplets in flight and increase the drying efficiency of the droplets, it is preferable to hold the droplets at a target temperature that is relatively high within a temperature at which the liquid does not boil. . On the other hand, when there is a difference in volume between the main droplet and the satellite droplet, a droplet with a small volume is likely to reach the target temperature, whereas a droplet with a large volume reaches the target temperature. It becomes difficult to do. In this way, in the case where the temperature varies greatly between the droplets in flight, in order to suppress the bumping and improve the drying efficiency, an excessive amount of heat is applied to one droplet that has reached the target temperature. An irradiation mode that suppresses the supply is required, and on the contrary, an irradiation mode that maintains a high heat supply for a droplet that has not reached the target temperature is required. Therefore, an irradiation mode for each droplet is required in one flight space, and there is a possibility that the laser light irradiation system is greatly complicated.

According to this pattern forming apparatus, both in-flight droplets coalesce before reaching the boiling point. Therefore, even if there is a temperature difference between the droplets in flight, both bumps can be reliably suppressed. And for the space where the united droplets fly, it is possible to continue supplying a high amount of heat suitable for the united droplets, improving the drying efficiency of the droplets and simplifying the irradiation system. You can also plan.

  In the pattern forming apparatus, the discharge control unit may be configured so that the droplet and the satellite droplet are united before the temperature of the droplet and the satellite droplet reaches the boiling point of the evaporation component. The gist is to perform control so that the velocity of the cutting point of the droplet on the nozzle side is higher than the velocity of the droplet.

  Examples of the target temperature that is relatively high among the temperatures at which the droplets in flight do not boil include the boiling point of the evaporation component. According to this pattern forming apparatus, since the boiling point uniquely defined according to the liquid is used as the target temperature, the droplets can be obtained without performing various experiments and numerical calculations for setting the target temperature. It is possible to improve the drying efficiency while suppressing the bumping.

In the pattern forming apparatus, the ejection control unit makes the volume of the droplet larger than the volume of the satellite droplet.
Droplets with a small volume are susceptible to air resistance during flight due to their low weight, and therefore tend to reduce flight speed compared to droplets with a large volume. And if the volume of the satellite droplet is smaller than the volume of the main droplet, the flight speed of the satellite droplet, which is in a position to catch up with the main droplet, will be relatively greatly reduced. In order to offset this decrease, it is necessary to further increase the flight speed of the satellite droplets. According to this pattern forming apparatus, by discharging satellite droplets larger than the volume of the main droplets, it is possible to avoid a drop in the flying speed of satellite droplets that are in the catch-up position. It is possible to reliably combine the droplets.

In the pattern forming apparatus, the laser irradiation unit irradiates a pair of laser beams opposed to the space.
When the droplet in flight evaporates the evaporation component, a reaction force against the kinetic force of the evaporation component acts on the droplet. Therefore, the reaction force from the higher evaporation rate to the lower one acts on the droplet, and the reaction force is asymmetric with respect to the droplet discharge direction and is excessive with respect to the droplet. In the case of action, the flying flight of the droplets due to the reaction force against the movement force occurs, and the landing position shifts.

  According to this pattern forming apparatus, a single droplet is irradiated with laser light from opposite directions, so that it is only possible to improve the drying efficiency of the droplet as compared with the case where laser light is irradiated from one side. In addition, by making the intensity distribution of the pair of laser beams equal, it is possible to suppress the flight bending of both the main droplet and the satellite droplet.

  Hereinafter, an embodiment in which the pattern forming apparatus of the present invention is embodied in a droplet discharge apparatus will be described with reference to FIGS. FIG. 1 is a perspective view schematically showing a perspective structure of a droplet discharge device. FIG. 2 is a perspective view showing a perspective structure of the ejection head of this embodiment, and FIG. 3 is a partial cross-sectional view showing an internal sectional structure of the ejection head. FIG. 4 is a plan view showing the arrangement relationship between the green sheet, which is a drawing object, and the ejection head.

As shown in FIG. 1, a stage 11 that can reciprocate along the longitudinal direction of the base 11 is mounted on the base 11 of the droplet discharge device 10. In the present embodiment, the longitudinal direction of the base 11, the upper right direction in FIG. 1 is the + X direction, and the opposite direction to the + X direction is the −X direction. Further, the horizontal direction orthogonal to the + X direction, the upper left direction in FIG. 2 is referred to as the + Y direction, and the opposite direction to the + Y direction is referred to as the −Y direction. Further, the upper direction in the vertical direction is defined as the + Z direction, and the direction opposite to the + Z direction is referred to as the −Z direction.

  On the upper surface of the stage 12 mounted on the base 11, a green sheet GS as a drawing object is positioned and fixed to the stage 12 with the drawing surface GSa facing upward. The stage 12 scans the positioned green sheet GS in the + Y direction or the −Y direction at a predetermined speed when the stage motor SM provided on the base 11 rotates forward or reverse.

  A guide member 13 formed in a gate shape is installed on the upper side of the base 11 along the + X direction, and an ink tank for supplying the conductive ink Ik as a liquid material is provided on the upper side of the guide member 13. 14 is disposed. The ink tank 14 stores the conductive ink Ik composed of a dispersion system of conductive fine particles, and supplies the stored conductive ink Ik to the discharge head 15 while adjusting a predetermined temperature under a predetermined pressure.

  The conductive fine particles as the pattern forming material are fine particles having a particle diameter of several nm to several tens of nm. For example, silver, gold, copper, platinum, palladium, rhodium, osmium, ruthenium, iridium, iron, tin, cobalt, A metal such as nickel, chromium, titanium, tantalum, tungsten, indium, or an alloy thereof can be used. The dispersion medium as the evaporation component may be any dispersion medium that uniformly disperses the conductive fine particles. For example, water or an aqueous solution mainly containing water or an organic solvent mainly containing an organic solvent such as tetradecane is used. be able to. In the conductive ink Ik of this embodiment, silver fine particles are used as conductive particles, and water is used as a dispersion medium. Such an aqueous dispersion medium can have a higher surface tension than an organic dispersion medium. And the droplet which consists of conductive ink Ik becomes easy to exhibit a spherical body, when such surface tension acts on the droplet surface.

  A carriage 16 that can move in the + X direction and the −X direction is mounted on the guide member 13, and an ejection head 15 is mounted on the carriage 16. The carriage 16 scans the ejection head 15 in the + X direction or the −X direction when a carriage motor CM (see FIG. 8) provided on the guide member 13 rotates forward or backward.

  As shown in FIG. 2, the ejection head 15 includes a head substrate 17 that is positioned and fixed to the carriage 16 and extends in the + X direction, and a head body 20 that is supported by the head substrate 17. A connection terminal 17 a is provided at the end of the head substrate 17 in the −X direction, and various control signals from the outside are input to the inside of the head main body 20 by the connection terminal 17 a and various detections from the head main body 20 are performed. The connection terminal 17a outputs a signal to the outside.

  A nozzle plate 21 disposed so as to face the green sheet GS is attached to the bottom of the head body 20. The nozzle plate 21 is configured such that when the head main body 20 is disposed immediately above the green sheet GS, the nozzle forming surface 21a, which is the bottom surface thereof, and the drawing surface GSa are substantially parallel to each other, and these nozzle forming surfaces 21a. And a flying space of liquid droplets, which is a space sandwiched between the drawing surface GSa. Further, when the head body 20 is disposed immediately above the green sheet GS, the nozzle plate 21 sets a platen gap PG, which is a distance between the nozzle forming surface 21a and the drawing surface GSa, to a predetermined distance (see FIG. 3, this embodiment). In the form, it is maintained at 1000 μm). On the nozzle forming surface 21a of the nozzle plate 21, a plurality (i) of nozzles N penetrating the nozzle plate 21 in the Z direction are arranged at equal intervals along the X direction at a nozzle pitch Dx.

As shown in FIG. 3, the head main body 20 includes a cavity 22 as a pressure chamber, a vibration plate 23, and a piezoelectric element PZ as a pressure generating element above each nozzle N. Each cavity 22 is connected to the common ink tank 14 via the supply tube 20T, and thereby accommodates the conductive ink Ik from the ink tank 14, and the conductive ink I.
k is supplied to each nozzle N. The diaphragm 23 vibrates in the Z direction in the region facing each cavity 22, thereby expanding and reducing the volume of the cavity 22 to generate pressure fluctuations, and a meniscus which is a gas-liquid interface formed in the nozzle N. Vibrate. Each piezoelectric element PZ is charged with a predetermined intermediate potential, and a drive signal COM having a signal waveform defining the contraction amount, contraction speed, extension amount and extension speed is input. Each time this drive signal COM is input to the piezoelectric element PZ, the piezoelectric element PZ is charged and discharged and contracts and expands in the Z direction, whereby the diaphragm 23 vibrates in the Z direction.

  In the ejection head 15 having such a configuration, when each piezoelectric element PZ contracts and expands in the Z direction, a part of the conductive ink Ik accommodated in each cavity 22 has a size and speed corresponding to the drive signal COM. The liquid droplets are ejected so as to have a tail. In the droplet discharged in this way, the dynamic surface tension of the liquid material acts on the spherical tip and the rear end corresponding to the tail, and the tip of the droplet is cut from the rear end. The main droplet Dm is generated in advance by the tip of the droplet. Further, the rear end portion of the droplet is cut from the nozzle, and the satellite droplet Ds is generated following the main droplet Dm. The satellite droplet Ds generated in this manner has an elongated shape in the ejection direction immediately after cutting, but gradually becomes spherical due to its surface tension and the like. When the satellite droplet Ds is in a spherical shape and has a slender shape and a velocity distribution is generated, the velocity is preserved. These droplets discharged from the nozzle N fly in the above-described flight space and land on the drawing surface GSa of the green sheet GS.

  The drive signal COM in the present embodiment is set so that the volume of the main droplet Dm described above is larger than the volume of the satellite droplet. Further, the satellite droplet Ds is fed from the nozzle N so that the main droplet Dm and the satellite droplet Ds are united after flying by an isolated flight distance PGa (<platen gap PG) which is a predetermined distance. When cutting, the velocity of the cutting point on the nozzle side of the satellite droplet Ds is set to be higher than the velocity of the main droplet Dm flying at that time. That is, the main droplet Dm and the satellite droplet Ds described above have a difference obtained by generating a combined droplet D after flying from the nozzle N by the isolated flight distance PGa, and subtracting the isolated flight distance PGa from the platen gap PG. Fly as a united drop D for a corresponding distance. According to such a configuration, the velocity of the cutting point on the nozzle side of the satellite droplet Ds is made higher than the velocity of the main droplet Dm so that the satellite droplet Ds is united with the main droplet Dm in flight. Therefore, contamination of the drawing surface GSa due to scattering of the satellite droplets Ds can be suppressed. Hereinafter, a space in which the main droplet Dm and the satellite droplet Ds fly in an isolated state is referred to as an isolated flight space A1, and a space in which the combined droplet D flies is referred to as a combined flight space A2.

  At this time, the droplet discharged from the nozzle N can fly along the Z direction from the nozzle N because the resultant force of the external force applied to the droplet acts only in the Z direction. It is possible to fly over the target route TL that is a virtual line extending in the Z direction. On the other hand, in the case where the resultant force of the external force applied to the droplet acts greatly in the direction intersecting the Z direction, the droplet discharged from the nozzle N is a route that deviates from the target route TL according to the action of the resultant force. So that the so-called flight curve, which is a factor that impairs the accuracy of the landing position, is caused.

By the way, in order to effectively evaporate a desired amount of the dispersion medium from such droplets, firstly, the droplets at room temperature are near the target temperature which is the highest temperature in the range where the liquid does not boil. It is necessary to raise the temperature to For example, it is necessary to supply a first heat quantity q1 that is a quantity of heat for raising the temperature of a droplet at room temperature to the boiling point of the dispersion medium. Next, it is necessary to supply the second liquid q2 which is latent heat (heat of vaporization) for smoothly causing phase transition of the dispersion medium into a gas while keeping the droplet heated by the first heat q1 from boiling. There is. And by supplying such first heat quantity q1 and second heat quantity q2 to the droplets at the timing described above,
A desired amount of dispersion medium can be effectively evaporated from the droplets. The first heat quantity q1 and the second heat quantity q2 can be estimated by calculation using the properties of the conductive ink Ik and the volume of the droplet, and can also be determined by direct measurement based on various experiments. .

  For example, when the first heat quantity q1 and the second heat quantity q2 are estimated by the above-described calculation, the molar fraction of the dispersion medium and the conductive fine particles obtained from the properties of the conductive ink Ik, the dispersion medium and the conductive fine particles This can be done based on the specific heat capacity, the weight of the droplet obtained based on the drive signal COM, and the temperature of the droplet at the time of ejection. Among the evaporation components evaporated from the minute droplets as described above, those that diffuse to a distance far away from the surface of the droplet and the partial pressure of the evaporation components remaining on the target route TL There is something to raise. For this reason, the evaporation amount of the droplets at each temperature increases as the concentration of the evaporation component remaining in the target path TL decreases, and conversely decreases as the concentration of the evaporation component in the target path TL increases. Therefore, the differential equation related to the mass balance of the droplet using the mass transfer flux of the evaporated component based on the density of the evaporated component on the droplet surface and its diffusion, etc., and the heat balance of the droplet considering the heat of vaporization of the droplet The first calorie q1 and the second calorie q2 can also be estimated by solving the differential equation relating to the above, and the equation of motion of the droplet considering the air resistance to the droplet.

  Further, when the first heat quantity q1 and the second heat quantity q2 are determined by the experiment described above, the droplets in flight are imaged with a high speed camera while irradiating the droplets with different heat amounts, It is also possible to obtain the first heat quantity q1 and the second heat quantity q2 by directly measuring the highest heat quantity that can maintain the state in which the droplets do not boil.

  The drying energy E, which is the sum of the first heat quantity q1 and the second heat quantity q2 described above, is a value that each of the main droplet Dm, the satellite droplet Ds, and the coalesced droplet D in which they are combined has a unique value. is there. Then, by providing such a specific drying energy E to the corresponding droplet, it is possible to realize a suitable dry state for each droplet. That is, the main dry energy, which is the dry energy specific to the main droplet Dm, is given to the isolated flight space A1, thereby realizing a suitable dry state for the main droplet Dm in flight. Alternatively, satellite drying energy, which is a drying energy specific to the satellite droplet Ds, is applied to the isolated flight space A1, thereby realizing a suitable dry state for the main droplet Dm in flight. Then, when the united drying energy, which is the drying energy E specific to the united droplet D, is given to the united flight space A2, a suitable dry state is realized for the united droplet D in flight.

  As shown by the one-dot chain line in FIG. 4, the drawing surface GSa of the green sheet GS is virtually divided by a dot pattern lattice DL which is a two-dimensional rectangular lattice. The dot pattern lattice DL is a virtual lattice in which the lattice interval in the + X direction and the lattice interval in the + Y direction are set at predetermined intervals. For example, the grid interval in the + X direction of the dot pattern grid DL is defined by the nozzle pitch Dx, and the grid spacing in the + Y direction of the dot pattern grid DL is the discharge cycle of the main droplet Dm and the scanning speed of the stage 12. It is defined by the discharge pitch Dy calculated from the product. When such a dot pattern grid DL is scanned by the stage 12, the above-described ejection head 15 is arranged such that each grid point T of the dot pattern grid DL crosses the target path TL, and the drawing surface GSa is drawn from each nozzle N. The selection as to whether or not to discharge the main droplet Dm toward is set for each lattice point T. In FIG. 4, for convenience of explaining each lattice point T of the dot pattern lattice DL, the lattice interval of the dot pattern lattice DL and the nozzle pitch Dx of the ejection head 15 are shown sufficiently enlarged.

Next, an optical system for irradiating the droplets in flight with laser light to dry the droplets will be described with reference to FIG. FIG. 5 is a diagram schematically illustrating the optical configuration of the laser irradiation unit 31 mounted on the droplet discharge device 10, and FIG. 6 schematically illustrates the irradiation angle of the laser light with respect to the combined droplets. It is a figure.

  As shown in FIG. 5, the laser irradiation unit 31 includes a laser light source 32 as a laser emission unit, a collimator lens 33, a half mirror 34 and reflection mirrors 35, 36, 37, 38, 39 as a branching unit, A laser forming part 40a and a second laser forming part 40b are provided.

  The laser light source 32 is a device that emits basic laser light Le whose cross-sectional intensity distribution is a Gaussian distribution. The laser light source 32 is a so-called semiconductor laser, and makes basic laser light Le set to a wavelength having a predetermined absorption rate for the conductive ink Ik incident on the collimating lens 33.

  The collimator lens 33 is a plano-convex lens having a predetermined curvature on the exit surface side, and converts the light beam of the basic laser light Le emitted from the laser light source 32 into parallel light parallel to the optical axis, thereby generating a half mirror. 34 is incident. The half mirror 34 divides the basic laser beam Le emitted from the collimator lens 33 into a first laser beam Le1 and a second laser beam Le2 that are a pair of laser beams having the same energy. Each of the reflecting mirrors 35 and 36 is a plane mirror having a reflecting surface that reflects the first laser beam Le1 that is the reflected light of the half mirror 34, and the first laser beam Le1 that is the reflected light is a first laser forming unit. It is made incident on 40a. Each of the reflection mirrors 37 to 39 is a plane mirror having a reflection surface that reflects the second laser beam Le2 that is the transmitted light of the half mirror 34, and the second laser beam Le2 that is the reflection light is a second laser forming unit. It is made incident on 40b.

  The first laser shaping unit 40a includes a cylindrical lens 41a and a diffractive optical element (DOE: Differential Optical Element, hereinafter referred to as DOE) 42a on the optical path of the first laser beam Le1. The second laser shaping unit 40b includes a cylindrical lens 41b and a DOE 42b on the optical path of the second laser beam Le2.

  The cylindrical lenses 41a and 41b are lenses each having an exit surface having a curvature only in the short direction, and the cross sections of the first laser light Le1 and the second laser light Le2 converted into parallel light by the collimating lens 33 are shown. It converts into the rectangular shape extended along the said nozzle formation surface 21a. The first laser light Le1 and the second laser light Le2 incident on the cylindrical lenses 41a and 41b have a predetermined width in the Z direction. Therefore, when the laser light is irradiated to the flight space without being formed by the cylindrical lenses 41a and 41b, the end portion in the Z direction of the laser light is the ejection head 15, the green sheet GS, the stage 12, and the like. And the energy of the first laser beam Le1 and the second laser beam Le2 is partially lost. The cylindrical lenses 41a and 41b convert the Z-direction components of the first laser light Le1 and the second laser light Le2 from the corresponding reflecting mirrors, respectively, and the first laser light Le1 and the second laser light Le2 in the Z direction. The cross-sectional shape is formed so that the length is equal to the platen gap PG (1000 μm in this embodiment). Thereby, the first laser beam Le1 and the second laser beam Le2 can be guided to the target path TL of the droplet while suppressing the energy loss of the first laser beam Le1 and the second laser beam Le2.

  The DOEs 42a and 42b convert the cross-sectional intensity distributions of the first laser beam Le1 and the second laser beam Le2 formed by the cylindrical lenses 41a and 41b into predetermined distributions and irradiate the flight space. The optical axes of the DOEs 42a and 42b are arranged so as to be positioned at intermediate positions of the target path TL, and the first laser beam Le1 and the second laser beam Le2 are applied to the droplets ejected from all the nozzles N. In order to irradiate, it is inclined in the horizontal direction by a predetermined inclination angle θ (θ: 0 ° <θ ≦ 90 °) with respect to the arrangement direction of the nozzles N (the one-dot chain line direction shown in FIG. 6).

  As shown in FIG. 6, the laser light irradiation system in the present embodiment has the above inclination angle θ from a range satisfying sin θ ≧ 2r / Dx, for example, when the diameter of the combined droplet D is r. Select. If the tilt angle θ satisfies such a condition, the liquid on the side relatively close to the DOE may be used even when the first laser beam Le1 and the second laser beam Le2 are irradiated to the droplets ejected at the same timing. The droplet does not block the laser beam with respect to the droplet on the side relatively far from the DOE. Therefore, the first laser beam Le1 and the second laser beam Le2 can be evenly irradiated to all droplets ejected simultaneously from the ejection head 15. In addition, when sin θ = 2r / Dx is satisfied, there is no gap in the laser light irradiation direction between the united droplets D ejected from the adjacent nozzles N, so that the laser light that passes through the flight space. Can be minimized and the utilization efficiency of laser light can be improved.

  The DOEs 42a and 42b are optical components that change the intensity distribution of the first laser light Le1 and the second laser light Le2, respectively. The DOEs 42a and 42b are arranged such that the intensity distributions of the first laser beam Le1 and the second laser beam Le2 have a flat top hat distribution along the target path TL in the target path TL included in the isolated flight space A1. Convert. The DOEs 42a and 42b have a top-hat distribution in which the intensity distribution of the first laser light Le1 and the second laser light Le2 is flat along the target path TL in the target path TL included in the united flight space A2. Convert to Since it is difficult to strictly flatten the intensity distribution of such laser light, the flat intensity distribution which is the top hat type distribution described above is the difference between the maximum intensity and the average intensity, and the minimum intensity. The distribution is such that the difference from the average intensity is within ± 5% of the average intensity. Such flatness is appropriately selected according to the accuracy of the landing position of the main droplet Dm, the accuracy of the landing diameter, and the like, which are the design rules for the drawing pattern.

  The intensities of the first laser beam Le1 and the second laser beam Le2 so that the DOEs 42a and 42b give the main drying energy or the satellite drying energy to the droplets on the target path TL included in the isolated flight space A1. Adjust. Further, the DOEs 42a and 42b give the cross-sectional intensities of the first laser beam Le1 and the second laser beam Le2 so that the DOEs 42a and 42b give the combined drying energy to the droplets on the target path TL included in the combined flight space A2. adjust. Furthermore, the DOEs 42a and 42b adjust the respective intensities so that the cross-sectional intensity of the first laser beam Le1 and the cross-sectional intensity of the second laser beam Le2 are equal throughout the flight space.

  The laser light intensity P per unit area and unit time of the laser light as described above is obtained by, for example, irradiating the flying droplets with laser beams having different intensities and imaging the flight state of the droplets with a high-speed camera. It can be obtained directly by selecting the highest value from the laser intensities at which the droplet does not bump. Alternatively, the laser intensity P can be simply estimated from the equation (1) by using the drying energy E inherent to the droplet to be dried and the radius r, flight distance L, and flight period t of the droplet. You can also L × 2r in equation (1) is the irradiation cross-sectional area of the laser beam with respect to the droplet in flight, and the flight period t in equation (1) is calculated from the flight speed v and the flight distance L of the droplet at t = Obtained as L / v.

P = E / ((L × 2r) × t) (1)
According to the DOEs 42a and 42b having such a configuration, it is possible to realize a suitable dry state for each droplet. That is, when the droplet main drying energy flying in the isolated flight space A1 is given, a suitable dry state is realized in the main droplet Dm in flight. In addition, when satellite drying energy is given to the droplet flying in the isolated flight space A1, a suitable dry state is realized in the satellite droplet Ds in flight. Then, a united drying energy is given to the united droplets D flying in the united flight space A2, whereby a suitable dry state is realized in the united droplets D in flight.

  As described above, when the volume of the satellite droplet Ds is smaller than the volume of the main droplet Dm, the evaporation amount required for the main droplet Dm is larger than the evaporation amount required for the satellite droplet Ds. And the main drying energy is higher than the satellite drying energy. In such a case, when the main drying energy is given to the isolated flight space A1, a suitable drying state is realized for the main droplet Dm, while the satellite droplet Ds is likely to bump due to excessive energy supply. . Therefore, when the main drying energy is sufficiently higher than the satellite drying energy, the DOEs 42a and 42b of the present embodiment give the satellite drying energy to the droplets in the isolated flight space A1. With such a configuration, drying of each droplet can be promoted while suppressing the bumping of the satellite droplet Ds.

  That is, by the cooperation of the ejection head 15 that receives the drive signal COM and the laser irradiation unit 31, the droplet ejection apparatus 10 allows the main droplet Dm before the main droplet Dm and the satellite droplet Ds boil. And the satellite droplet Ds. Therefore, even if a large temperature difference occurs between the droplets in flight, the bumping of each droplet can be reliably suppressed. Even when the main droplet Dm becomes insufficiently dried in the isolated flight space A1, since the drying energy E unique to the combined droplet D is given to the combined flight space A2, the conductive ink Ik at the time of landing is provided. A more preferable dry state is realized. In such a configuration, the main droplet Dm and the satellite liquid are before the temperature of the main droplet Dm reaches the boiling point of the dispersion medium and before the temperature of the satellite droplet Ds reaches the boiling point of the dispersion medium. A configuration in which the velocity of the cutting point on the nozzle side of the satellite droplet Ds is higher than the velocity of the main droplet Dm so that the droplet Ds is united with each other is preferable. With such a configuration, the boiling point that is uniquely defined based on the properties of the conductive ink Ik can be used as a target temperature for obtaining the drying energy E. Therefore, various experiments and numerical calculations for setting the target temperature are performed. Without carrying out the steps, it is possible to improve the bumping efficiency of the droplets and the drying efficiency.

  As described above, when the droplet in flight evaporates the dispersion medium, a reaction force against the kinetic force of the dispersion medium acts on the droplet to be dried. Therefore, when an external force from the higher evaporation rate to the lower one acts on the flying droplet, and the evaporation rate is not symmetric with respect to the target path TL, the flying of the droplet is caused by the accompanying external force. Bending is likely to be induced. On the other hand, if the cross-sectional intensity of the first laser beam Le1 and the cross-sectional intensity of the second laser beam Le2 are equal as described above, the evaporation rate of each droplet is symmetric with respect to the target path TL. The reaction forces acting on the liquid droplets cancel each other, and the flying curve of the liquid droplet is less likely to occur. The drive signal COM in the present embodiment makes the velocity of the cutting point on the nozzle side of the satellite droplet Ds higher than the velocity of the main droplet Dm so that the satellite droplet Ds in flight is united with the main droplet Dm. However, by applying the irradiation mode as described above, the flight bending of each droplet can be suppressed. For this reason, it becomes possible to further expand the degree of freedom of various drawing conditions such as the range of velocity of each droplet and the range of laser intensity.

  Next, the electrical configuration of the droplet discharge device 10 configured as described above will be described with reference to FIG. FIG. 7 is a block circuit diagram showing the electrical configuration of the droplet discharge device 10, and FIG. 8 is a block circuit diagram showing the electrical configuration of the head drive circuit.

As shown in FIG. 7, the control device 50 of the droplet discharge device 10 includes a control unit 51 including a CPU, a ROM 52, a RAM 53, and the like. In accordance with various data and various control programs stored in the ROM 52 and RAM 53, the control device 50 performs a transport process using the stage 12 and the carriage 16, a droplet discharge process using the discharge head 15, and a laser using the laser light source 32. Various processes such as a light emission process are executed. The control device 50 also includes an oscillation circuit 54 that generates a clock signal, a drive waveform generation circuit 55 that generates a signal related to the waveform of the drive signal COM, an external I / F 56 that receives various signals, and various signals. Internal I to send / receive
/ F57.

  The control device 50 is electrically connected to the input / output device 58 via an external I / F 56, and also includes a carriage motor drive circuit 59, a stage motor drive circuit 60, a head drive circuit 61, and the like via an internal I / F 57. The laser light source driving circuit 62 is electrically connected. The control device 50 and the head drive circuit 61 constitute an ejection control unit.

  The input / output device 58 is an external computer having, for example, a CPU, RAM, ROM, hard disk, liquid crystal display, and the like. The input / output device 58 inputs information relating to the drawing pattern, information relating to the waveform of the drive signal COM, information relating to the intensity of the laser light, and the like to the control device 50 as drawing information Ia. The control device 50 receives the drawing information Ia from the input / output device 58 and stores the drawing information Ia in the storage area of the RAM 53.

  The information related to the drawing pattern is data in which the target position for discharging the droplet is associated with the dot pattern grid DL, and is image data indicating the drawing pattern, for example. The information regarding the waveform of the drive signal COM is data indicating a signal waveform supplied to the piezoelectric element PZ. The information regarding the waveform of the drive signal COM is such that the volume of the main droplet Dm is larger than the volume of the satellite droplet, and the main droplet Dm and the satellite droplet Ds are united after flying the isolated flight distance PGa. Furthermore, the data is set based on discharge experiments and numerical calculations of various droplets so that the velocity of the cutting point on the nozzle side of the satellite droplet Ds is higher than the velocity of the main droplet Dm. The information regarding the intensity of the laser beam is data indicating the output of the laser light source 32, and is data set to irradiate the laser irradiation unit 31 with the laser beam having a predetermined laser intensity.

  The oscillation circuit 54 generates a clock signal for controlling the timing of various processes. For example, the oscillation circuit 54 generates a transfer clock CLK that is a synchronization signal for serially transferring various data read from the RAM 53 to the head drive circuit 61.

  The drive waveform generation circuit 55 has a waveform memory in which waveform data for generating the drive signal COM is stored in a predetermined storage area. The drive waveform generation circuit 55 also has a digital / analog converter that converts voltage level data for generating the drive signal COM into an analog signal, and the piezoelectric element PZ drives the analog signal converted by the digital / analog converter. An amplifier for amplifying the voltage to a voltage and supplying a current corresponding to the amplified voltage signal is provided. The waveform data is data indicating the amount of step-up or step-down for each reference clock. The voltage level data is voltage level data indicating a voltage level corresponding to the waveform of the drive signal COM, and is generated by adding the waveform data described above in synchronization with the reference clock.

  In the drive waveform generation circuit 55 having such a configuration, when a data signal indicating waveform data and an address signal indicating a write address of the waveform data are input from the control unit 51, the waveform data is stored in the storage area corresponding to the address. Is stored. When the droplet discharge operation is performed, for example, when the grid point T is located immediately below the nozzle N, an address signal indicating a read address is input from the control unit 51 in synchronization with the reference clock, and the address The waveform data stored in is read out. Then, the drive waveform generation circuit 55 generates voltage level data based on the read waveform data, converts the voltage level data into an analog signal, and uses the amplified voltage signal to generate a current signal corresponding to the voltage signal as a drive signal. Output as COM.

When the control signal from the control device 50 is input, the carriage motor drive circuit 59 rotates the carriage motor CM for moving the carriage 16 forward or backward in response to the control signal. A carriage encoder CE is connected to the carriage motor drive circuit 59, and a detection signal is input from the carriage encoder CE. The carriage motor drive circuit 59 generates a signal related to the movement direction and movement amount of the carriage 16 with respect to the drawing surface GSa, that is, a signal related to the movement direction and movement amount of the nozzle N based on the detection signal from the carriage encoder CE. Output to.

  When the control signal from the control device 50 is input, the stage motor drive circuit 60 rotates the stage motor SM for moving the stage 12 in the forward or reverse direction in response to the control signal. A stage encoder SE is connected to the stage motor drive circuit 60, and a detection signal is input from the stage encoder SE. Based on the detection signal from the stage encoder SE, the stage motor driving circuit 60 generates a signal related to the moving direction and moving amount of the stage 12, that is, a signal related to the moving direction and moving amount of the lattice point T that is the target position. Output to the controller 50.

  The laser light source driving circuit 62 receives a control signal from the control device 50 when the green sheet GS starts to enter immediately below the nozzle N, and responds to the control signal to the laser light source 32 with the laser light having the laser intensity P. Is emitted.

  The control unit 51 generates dot pattern data based on information related to the drawing pattern. The dot pattern data is bitmap data that associates whether or not the main droplet Dm is ejected to all the lattice points T. Using this dot pattern data, serial data synchronized with the transfer clock CLK is generated, and the serial data is serially transferred to the head drive circuit 61 via the internal I / F 57. In the present embodiment, the serial data generated based on the dot pattern data is referred to as serial pattern data SI. The serial pattern data SI is data for associating ejection and non-ejection of the main droplet Dm with each piezoelectric element PZ.

  The control unit 51 receives a signal related to the moving direction and moving amount of the stage 12 from the stage encoder SE described above, that is, a signal related to the moving direction and moving amount of the lattice point T that is the target position with respect to the nozzle N. It is determined whether or not it is located immediately below the nozzle N. A timing signal LAT is generated when the lattice point T is located immediately below the nozzle N, and the timing signal LAT is output to the head drive circuit 61.

  As shown in FIG. 8, the head drive circuit 61 includes a shift register 63, a control signal generation unit 64, a level shifter 65, and a piezoelectric element switch 66. The shift register 63 sequentially shifts the serial pattern data SI transferred from the control device 50 and stores serial pattern data SI composed of i bit values that are the number of nozzles N.

  The control signal generating unit 64 receives the timing signal LAT from the control device 50 and latches the serial pattern data SI stored in the shift register 63. The control signal generation unit 64 performs serial / parallel conversion on the serial pattern data SI, generates i-bit parallel data corresponding to each nozzle N, and outputs the parallel data to the level shifter 65. In the present embodiment, the parallel data output from the control signal generator 64 is referred to as parallel pattern data PI.

The level shifter 65 boosts the parallel pattern data PI from the control signal generator 64 to the drive voltage level of the piezoelectric element switch 66 to generate i open / close signals associated with each piezoelectric element PZ. The piezoelectric element switch 66 has i switch elements corresponding to each piezoelectric element PZ, and the drive signal COM from the control device 50 is input to the input terminal of each switch element, and the output of each switch element. From the end, a drive signal COM is sent to the corresponding piezoelectric element PZ. These switch elements receive an open / close signal associated with the piezoelectric element PZ to which the switch element is connected, and thereby output a drive signal COM to the piezoelectric element PZ.

  According to such a configuration, each time the timing signal LAT is input to the head drive circuit 61, the piezoelectric element PZ corresponding to the nozzle N is selected based on the dot pattern data, and the drive signal COM is supplied to the piezoelectric element PZ. Is output. Then, the main droplet Dm and the satellite droplet Ds are ejected from the nozzle N corresponding to the selected piezoelectric element PZ, and the main droplet Dm and the satellite droplet Ds are formed at the lattice point T immediately below the nozzle N. Land in the form of overlapping.

  Next, the drive signal COM generated by the drive waveform generation circuit 55 will be described with reference to FIGS. FIG. 9 shows the waveform of the voltage signal generated by the drive waveform generation circuit 55 to generate the drive signal COM, and FIG. 10 shows the flight state of the droplets ejected by the drive signal COM over time. Yes, the flight time has passed in order from the leftmost droplet to the rightmost droplet. In FIG. 10, the initial state in the discharge operation is shown at the left end, the flight state of the main droplet Dm and the satellite droplet Ds is shown in the center, and the main droplet Dm and the satellite droplet Ds are united. Is shown at the right end.

  As shown in FIG. 9, the waveform of the voltage signal corresponding to the drive signal COM includes the first waveform portion 71, the second waveform portion 72, the third waveform portion 73, the fourth waveform portion 74, the fifth waveform portion 75, The sixth waveform portion 76 and the seventh waveform portion 77 are configured. The first waveform portion 71 increases the voltage level from the reference potential V0 to the first potential V1, and the second waveform portion 72 maintains the voltage level from the end of the first waveform portion 71.

  The third waveform portion 73 lowers the voltage level from the end of the second waveform portion 72 to the second potential V2. The third waveform portion 73 defines the volume reduction amount and the reduction speed of the cavity 22, and defines the volume and speed of the main droplet Dm based on the voltage level difference and change rate between both ends thereof. The third waveform portion 73 is determined by direct measurement or various numerical calculations based on various experiments or the like in order to give a desired volume and velocity to the main droplet Dm. The fourth waveform portion 74 is a waveform for forcibly splitting the main droplet Dm and the satellite droplet Ds while maintaining the voltage level from the end of the third waveform portion 73.

  The fifth waveform portion 75 has both a voltage level difference and a change rate between both ends larger than those of the third waveform portion 73, and the voltage level is lowered from the end of the fourth waveform portion 74 to the third potential V3. The fifth waveform portion 75 defines the volume and velocity of the satellite droplet Ds by the difference in voltage level and the rate of change between both ends thereof. The fifth waveform portion 75 is determined by direct measurement or various numerical calculations based on various experiments or the like in order to give a desired volume and velocity to the satellite droplet Ds. The sixth waveform portion 76 maintains the voltage level from the end of the fifth waveform portion 75, and the seventh waveform portion 77 raises the voltage level from the end of the sixth waveform portion 76 to the reference potential V0.

  When a drive signal COM corresponding to such a voltage waveform is supplied to the piezoelectric element PZ, the piezoelectric element PZ contracts in response to a current signal corresponding to the first waveform portion 71, whereby the volume of the cavity 22 is in an initial state. Expand from. Then, the conductive ink Ik is introduced into the cavity 22. Next, in response to a current signal corresponding to the second waveform portion 72, the piezoelectric element PZ maintains its contracted state, whereby the volume of the cavity 22 is maintained in an expanded state. Then, the phase of the meniscus vibration generated by the volume expansion of the cavity 22 is adjusted. Subsequently, upon receiving a current signal corresponding to the third waveform portion 73, the piezoelectric element PZ expands, whereby the volume of the cavity 22 is reduced at a speed corresponding to the rate of change of the third waveform portion 73. Then, the conductive ink Ik in the cavity 22 is pressurized. When the meniscus subjected to such pressure is pushed out of the nozzle N, an ink column having a hemispherical tip is formed from the nozzle N.

  Next, in response to a current signal corresponding to the fourth waveform portion 74, the piezoelectric element PZ maintains that state only for the period of the fourth waveform portion 74, whereby the volume of the cavity 22 is maintained. At this time, the conductive ink Ik that has flowed due to the pressurization of the third waveform portion 73 in the previous stage is suppressed from flowing to the ink column, and the meniscus at the peripheral edge of the nozzle N is caused by the residual vibration. It moves to be pulled back to N. At this time, the movement of the meniscus is not suppressed by maintaining the volume of the cavity 22 only during the period of the fourth waveform portion 74. On the other hand, the tip of the ink column described above is not pulled back to the nozzle N and continues to move in the ejection direction by inertial force. As a result, at the end of the fourth waveform portion 74, the above-described ink column is formed in a tapered shape.

  Next, in response to the current signal corresponding to the fifth waveform portion 75, the piezoelectric element PZ expands again, whereby the volume of the cavity 22 is reduced at a speed corresponding to the inclination of the fifth waveform portion 75. Then, the conductive ink Ik in the cavity 22 is pressurized again. When the meniscus subjected to such pressurization is further pushed out from the nozzle N, a new ink column is formed in a form connected to the previously formed ink column.

  Next, in response to a current signal corresponding to the sixth waveform portion 76, the piezoelectric element PZ maintains that state only for the period of the sixth waveform portion 76, whereby the volume of the cavity 22 is maintained. At this time, the conductive ink Ik that has flowed due to the pressurization of the fifth waveform portion 75 in the previous stage is suppressed from flowing to the subsequent ink column, and the meniscus at the peripheral portion of the nozzle N is caused by the residual vibration accompanying this. It moves so as to be pulled back to the nozzle N. At this time, the movement of the meniscus is not suppressed by maintaining the volume of the cavity 22 only during the period of the sixth waveform portion 76. On the other hand, each of the ink columns formed by the third waveform portion 73 and the fifth waveform portion 75 is not pulled back to the nozzle N and continues to move in the ejection direction by inertia force. As a result, at the end of the sixth waveform portion 76, the preceding ink column and the succeeding ink column are easily cut off naturally. Then, the preceding ink column is separated from the succeeding ink column and ejected as the main droplet Dm.

  Next, in response to the current signal corresponding to the seventh waveform portion 77, the piezoelectric element PZ contracts, thereby expanding the volume of the cavity 22. Then, when the volume of the cavity 22 is restored to the initial state, the base end portion of the succeeding ink column is cut off from the nozzle N, and as shown on the left side of FIG. Ds is discharged.

  In addition, the seventh waveform portion 77 is input at a timing when the residual vibration of the meniscus turns in the direction of ejection from the nozzle, and the vibration of the meniscus moving toward the direction of ejection from the nozzle is increased by increasing the volume of the cavity 22. Offset (vibration suppression).

The two droplets ejected in this way each fly as a sphere due to their surface tension. At this time, the main droplet Dm generated based on the third waveform portion 73 is discharged at a speed (main discharge speed v <b> 1) corresponding to the voltage level change rate in the third waveform portion 73. The satellite droplet Ds generated based on the fifth waveform portion 75 has an elongated shape at the beginning of ejection, and the tip in the ejection direction is influenced by the main droplet Dm when ejected. While discharging is performed at a speed slower than the speed v <b> 1, the speed at the cutting point on the nozzle N side, which is the end of the tail, is discharged at a speed corresponding to the rate of change of the voltage level in the fifth waveform portion 75. Then, the tail part catches up with the tip part and is discharged at a speed that is preserved and higher than the main discharge speed v1 (satellite discharge speed v2). When the main droplet Dm and the satellite droplet Ds fly for an isolated flight distance PGa, the high-speed satellite droplet Ds catches up with the low-speed main droplet before the main droplet Dm and the satellite droplet Ds boil. The main droplet Dm and the satellite droplet Ds are united. The coalesced droplet D generated in this manner receives coalescing drying energy in the coalescing flight space A2, and lands on the target position in a sufficiently dry state.

  During this time, a pair of laser beams facing each other is irradiated to each droplet with the same intensity. Therefore, it is difficult for each droplet to be bent in flight, thereby suppressing the displacement of the landing position. However, it may be difficult to make the intensity of such a pair of laser beams exactly equal. For this reason, when the intensity of the pair of laser beams is different, the flying droplet is more susceptible to the light pressure from the laser beam and the reaction force accompanying the evaporation of the dispersion medium as the weight of the droplet decreases. In addition, a droplet in flight becomes more susceptible to air resistance as its weight decreases. That is, the satellite droplet Ds is likely to be bent by flight. Therefore, in order to suppress such flight bending of the satellite droplet Ds, it is preferable to combine the main droplet Dm and the satellite droplet Ds at an earlier stage.

As described above, according to the droplet discharge device 10 of the above embodiment, the following effects can be obtained.
(1) According to the above embodiment, the main droplet Dm and the satellite droplet Ds are united after flying the isolated flight distance PGa from the nozzle forming surface 21a, and therefore the drawing surface GSa due to the scattering of the satellite droplet Ds. Contamination can be suppressed.

  (2) Also, by supplying drying energy to each droplet based on the satellite droplet Ds that is a droplet having a small volume in the isolated flight space A1, both the main droplet Dm and the satellite droplet Ds boil. It can be made to unite before, and bumping of these droplets can be suppressed reliably.

  (3) By irradiating the first and second laser beams Le1 and Le2, which are a pair of laser beams opposed to each droplet, with an equal intensity distribution, the flight bending of each droplet is suppressed and united. It is also possible to suppress the displacement of the landing position of the droplet D with respect to the lattice point T.

In addition, the said embodiment can also be changed and implemented as follows.
-In the optical system of the laser irradiation part 31 in the said embodiment, a laser beam is irradiated from both sides of a droplet so that the droplet in flight may be pinched | interposed. By changing these irradiation modes, for example, when the flying weight is very small, such as when each droplet is heavy and its flight speed is fast, or even if a flying bend occurs, the displacement of the landing position can be allowed. In a simple drawing pattern, the laser beam may be irradiated from only one side of the droplet. Even in such a case, it is possible to improve the pattern shape accuracy and the drying efficiency by the amount that the satellite droplet Ds is ejected close to the volume of the main droplet Dm.

  In the voltage waveform in the above embodiment, as shown in FIG. 9, an example is shown in which the voltage level difference between both ends of the fifth waveform portion 75 is smaller than that of the third waveform portion 73. The volume of the satellite droplet is smaller than the volume of the main droplet Dm, and when the satellite droplet Ds is cut from the nozzle N, the velocity of the cutting point on the nozzle N side of the satellite droplet Ds is in flight at that time. In this example, the velocity of the main droplet Dm is higher than that of the main droplet Dm. However, the voltage waveform corresponding to the drive signal COM can be changed as follows. FIG. 11 and FIG. 12 correspond to FIG. 9 and FIG. 10 of the above embodiment in this modified example.

As shown in FIG. 11, the voltage waveform corresponding to the drive signal COM may be configured such that the voltage level difference between both ends of the fifth waveform portion 75 is larger than that of the third waveform portion 73, for example. That is, a configuration in which the volume of the satellite droplet Ds is larger than the volume of the main droplet Dm and the speed of the cutting point on the nozzle N side of the satellite droplet Ds may be higher than the velocity of the main droplet Dm. Even in such a configuration, as shown in FIG. 11, since the satellite discharge speed v2 is higher than the main discharge speed v1, if the main droplet Dm and the satellite droplet Ds fly by the isolated flight distance PGa, the main liquid Before the droplet Dm and the satellite droplet Ds boil, the high-speed satellite droplet Ds catches up with the low-speed main droplet Dm, and the main droplet Dm and the satellite droplet Ds are united. Therefore, the same kind of effect as that of the above-described embodiment can be obtained.

  In addition, a droplet having a small volume is easily affected by air resistance during flight due to its small weight, and therefore, the flight speed is likely to be reduced as compared with a droplet having a large volume. With such a configuration, since satellite droplets Ds larger than the volume of the main droplet Dm are ejected, it is possible to avoid a decrease in flight speed of the satellite droplet Ds that is in a catch-up position. The satellite droplets Ds can be reliably combined.

  In the above embodiment, as shown in FIG. 9, the drive signal COM is generated with a voltage waveform in which the third potential V3 is lower than the reference potential V0, and the satellite droplet Ds is cut off on the nozzle N side by such drive signal COM. The satellite discharge speed v2 was made higher than the main discharge speed v1 by increasing the dot speed. The voltage waveform for making the satellite discharge speed v2 higher than the main discharge speed v1 is not limited to this. For example, as shown in FIGS. 13A and 13B, the first to third potentials V1 to V3 are set to the reference potential V0. A larger drive signal COM may be used.

  In the optical system of the laser irradiation unit 31 in the above embodiment, the configuration in which the optical axes of the first laser beam Le1 and the second laser beam Le2 are inclined by the inclination angle θ with respect to the arrangement direction of the nozzles N has been described. The configuration is not limited to such an irradiation mode, and the optical axes of the first laser beam Le1 and the second laser beam Le2 may be configured to coincide with the arrangement direction without being inclined with respect to the arrangement direction of the nozzles N. In such a configuration, each droplet is ejected from each nozzle N of the ejection head 15 at different ejection timings, so that all the droplets are irradiated with laser light.

  -In the said embodiment, although water was used as a dispersion medium of a liquid, it is not restricted to this, You may utilize the dispersion medium which added surfactant as a liquid. According to this, it becomes possible to adjust the surface tension at the meniscus according to the addition amount, and the degree of freedom related to the adjustment of the drive signal COM can be expanded.

  In the optical system of the laser irradiation unit 31 in the above embodiment, the basic laser light Le emitted from one laser light source 32 is branched into the first laser light Le1 and the second laser light Le2 via the half mirror 34. Explained the configuration. In addition to such an optical system, a configuration in which a pair of laser light sources is used to emit a pair of laser beams, for example, as long as the laser beams are irradiated from both sides of the droplet so as to sandwich the droplet in flight. There may be. According to such a configuration, the droplet discharge device can omit the half mirror 34.

  In the above embodiment, the laser light applied to the droplet is a semiconductor laser. However, the present invention is not limited to this, and a solid laser such as a liquid laser, a gas laser, or a YAG laser may be used for irradiating the droplet with laser light. When a YAG laser is used, it is preferable to select whether or not to irradiate the flight space with laser light by arranging a shutter on the optical path of the basic laser light and controlling the opening and closing.

  In the above embodiment, the configuration in which the ejection head 15 has one nozzle row has been described. In addition to such a configuration, the ejection head 15 may have a plurality of nozzle rows. In such a configuration, when the tilt angle θ of the optical axis of the laser beam is appropriately changed so that the first laser beam Le1 and the second laser beam Le2 are irradiated to all droplets ejected from the nozzle N. Good.

In the above embodiment, the pattern forming apparatus that draws the metal wiring by discharging the conductive ink Ik containing conductive fine particles on the green sheet GS has been described. However, the present invention is not limited to this, and may be embodied in a pattern forming apparatus for other uses, such as a pattern forming apparatus that draws an insulating pattern, as long as the flying droplets are irradiated with laser light and dried.

  In the above embodiment, the piezoelectric element driving method has been described as the ejection head driving method. Not only such a driving method but also a resistance heating method and an electrostatic driving method can be used from the viewpoint of discharging droplets from the discharge head.

The perspective view which showed the perspective structure of the pattern formation apparatus in this embodiment. The perspective view which showed the perspective structure of the discharge head. FIG. 3 is a partial cross-sectional view showing the internal structure of the ejection head. The schematic diagram which showed the dot pattern lattice formed in a green sheet. The block diagram which showed typically the optical system of a droplet discharge apparatus. The schematic diagram for demonstrating the relationship between the advancing direction of a laser beam, and the position of a droplet. The block circuit diagram which showed the electric constitution of the droplet discharge apparatus. FIG. 3 is a block circuit diagram showing an electrical configuration of a head drive circuit. The figure which showed the voltage waveform corresponding to a drive signal. The figure which showed typically the discharge condition based on a drive signal. The figure which showed the voltage waveform of the drive signal in the example of a change. The figure which showed typically the discharge condition based on a drive signal. (A) (b) The figure which showed the voltage waveform corresponding to the drive signal in the example of a change. The figure which showed the landing condition of the main droplet and a satellite droplet in a prior art example.

Explanation of symbols

  θ: Inclination angle, A1: Isolated flight space, A2: Combined flight space, CE: Carriage encoder, CLK: Transfer clock, CM: Carriage motor, COM: Drive signal, D: Combined droplet, DL: Dot pattern grid , Dm ... main droplet, Ds ... satellite droplet, Dx ... nozzle pitch, Dy ... discharge pitch, E ... drying energy, GS ... green sheet, GSa ... drawing surface, Ia ... drawing information, Ik ... conductive ink, L ... Flight distance, N ... Nozzle, P ... Laser intensity, r ... Radius, t ... Flight period, T ... Lattice point, Le ... Basic laser beam, PG ... Platen gap, PI ... Parallel pattern data, PZ ... Piezoelectric element, q1 ... first heat quantity, q2 ... second heat quantity, SE ... stage encoder, SI ... serial pattern data, SM ... stage motor, TL ... target path, V0 ... reference potential, ... flight speed, v1 ... main discharge speed, v2 ... satellite discharge speed, V1 ... first potential, V2 ... second potential, V3 ... third potential, LAT ... timing signal, Le1 ... first laser beam, Le2 ... second Laser light, PGa ... isolated flight distance, 10 ... droplet ejection device, 11 ... base, 12 ... stage, 13 ... guide member, 14 ... ink tank, 15 ... ejection head, 16 ... carriage, 17 ... head substrate, 17a DESCRIPTION OF SYMBOLS ... Connection terminal, 20 ... Head main body, 20T ... Supply tube, 21 ... Nozzle plate, 21a ... Nozzle formation surface, 22 ... Cavity, 23 ... Vibration plate, 31 ... Laser irradiation part, 32 ... Laser light source, 33 ... Collimating lens, 34 ... Half mirror, 35 ... Reflection mirror, 36 ... Reflection mirror, 40a ... First laser molding part, 40b ... Second laser molding part, 41a ... Cylindrical laser 41b ... cylindrical lens, 42a ... DOE, 42b ... DOE, 50 ... control device, 51 ... control unit, 52 ... ROM, 53 ... RAM, 54 ... oscillation circuit, 55 ... drive waveform generation circuit, 56 ... external I / F, 57 ... Internal I / F, 58 ... I / O device, 59 ... Carriage motor drive circuit, 60 ... Stage motor drive circuit, 61 ... Head drive circuit, 62 ... Laser light source drive circuit, 63 ... Shift register, 64 ... Control Signal generation unit 65. Level shifter 66. Piezoelectric element switch 71 71 First waveform portion 72 72 Waveform portion 73 73 Waveform portion 74 74 Waveform portion 75 75 Waveform portion 76 ... 6th waveform part, 77 ... 7th waveform part.

Claims (5)

A pressure chamber for storing a liquid material containing an evaporation component and a pattern forming material, a pressure generating element that fluctuates the pressure in the pressure chamber, and a nozzle communicating with the pressure chamber, and drawing a droplet made of the liquid material from the nozzle An ejection head for ejecting toward an object;
A discharge controller for driving the pressure generating element;
A laser irradiation unit that irradiates laser light to a space between the nozzle and the drawing object to evaporate the evaporation component from the droplets in flight;
A pattern forming apparatus for forming a pattern with the droplets landed on the drawing object,
The discharge controller is
When the satellite droplet is cut from the nozzle so that the satellite droplet generated as the droplet is ejected merges with the droplet in flight, the satellite droplet is cut on the nozzle side. A pattern forming apparatus characterized in that a dot velocity is higher than a droplet velocity. The discharge controller is
The velocity of the cutting point on the nozzle side of the satellite droplet is higher than the velocity of the droplet so that the droplet and the satellite droplet merge before the droplet and the satellite droplet boil. The pattern forming apparatus according to claim 1, wherein control is performed. The discharge controller is
The velocity of the cutting point on the nozzle side of the satellite droplet is adjusted so that the droplet and the satellite droplet are united before the temperature of the droplet and the satellite droplet reaches the boiling point of the evaporation component. The pattern forming apparatus according to claim 2, wherein control is performed to make the speed higher than the speed of the droplet. The discharge controller is
The pattern forming apparatus according to claim 1, wherein a volume of the droplet is made smaller than a volume of the satellite droplet. The laser irradiation unit is
The pattern formation apparatus of any one of Claims 1-4 which irradiate a pair of laser beam which opposes the said space.

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