JP2010099598A - Pattern formation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pattern formation apparatus which dries flying droplets by irradiating the flying droplets with a laser beam and is improved in drying efficiency and landing precision for flying droplets. <P>SOLUTION: A controller generates drive signals COM for discharging main droplets and satellite droplets with equal volumes and flying speeds and outputs the drive signals to a head driving circuit 61. Use of such drive signals COM allows satellite droplets to land so as to be superimposed on main droplets having landed, resulting in an improvement of the shape precision of the pattern. For a given amount of droplets, the discharge of two types of droplets, instead of discharge of a single-type droplets, enables the enlargement of the irradiation cross-section irradiated with the laser beam, leading to an improvement in drying efficiency. <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 droplets discharged in this way, the dynamic surface tension of the liquid acts on the spherical tip and the rear end corresponding to the tail, so that the front and rear ends of the droplet are in flight. The main droplet is generated by the leading end of the droplet, and the minute satellite droplet following the main droplet is generated by the trailing end of the droplet. Since these droplets have different sizes and flight speeds, the energy received from the laser light during flight varies. Therefore, if the irradiation condition of the laser beam is selected so that the main droplet is landed at an appropriate landing position in a desired dry state, the above-described minute satellite droplets are caused to evaporate light pressure from the laser beam or evaporation component. Due to the influence of external force such as reaction force and air resistance during flight, a large flight bend is caused, and eventually landing on a region different from the discharge region to contaminate the drawing surface on the substrate. On the other hand, when the laser light irradiation conditions are selected based on the satellite droplets, the main droplets are deficient in drying and spread after wetting.

  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 provide a pattern forming apparatus for irradiating a flying droplet with a laser beam to dry the flying droplet. An object of the present invention is to provide a pattern forming apparatus with improved drying efficiency and landing accuracy.

  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 liquid droplets from the nozzle toward the drawing target, a discharge control unit that drives the pressure generating element, and 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 gist is to perform control so that the volume of the satellite droplet generated as the droplet is ejected is the same as the volume of the droplet.

  When ejecting droplets by vibrating a meniscus, which is a gas-liquid interface of a liquid material formed on a nozzle, the droplets ejected from the vibrating meniscus are generally generated in the form of a tail. In the droplets discharged in this way, the dynamic surface tension of the liquid acts on the spherical tip and the rear end corresponding to the tail, so that the front and rear ends of the droplet are in flight. The main droplet is generated by the leading end portion of the droplet, and the satellite droplet following the main droplet is generated by the trailing end portion of the droplet. In a pattern forming apparatus that irradiates a laser beam to a droplet in flight, both the main droplet and the satellite droplet are irradiated with a laser beam. It will be divided into a volume and a volume of satellite droplets. According to this pattern forming apparatus, the volume of the satellite droplets is brought close to the volume of the main droplets. Therefore, when discharging the liquid material of the same volume, the drying rate of the main droplets and the drying rate of the satellite droplets are Can be brought closer. Therefore, the difference between the drying speed of the main droplet and the satellite droplet can be reduced by the amount that brings the volume of the satellite droplet closer to the main droplet, and consequently the drying speed of the discharged liquid itself is increased. be able to.

  In addition, droplets in flight that receive laser light are bent more due to the effects of external forces such as the reaction pressure associated with the light pressure from the laser light and the 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, since main droplets and satellite droplets having substantially the same volume are ejected, the flight bending of both the main droplets and the satellite droplets is suppressed, and the flight bending is caused. Also, the relative landing position is maintained, and these can be superimposed on the drawing object.

The gist of the pattern forming apparatus is that the ejection control unit performs control so that the speed at which the satellite droplets are ejected is the same as the speed at which the droplets are ejected.
According to this pattern forming apparatus, since the main droplet and the satellite droplet are ejected at substantially the same speed, the flight times of the main droplet and the satellite droplet can be made substantially equal. Therefore, since the irradiation time of the laser beam is approximately equal between the main droplet in flight and the satellite droplet in flight, the difference in the respective drying speeds becomes even smaller, and the drying speed of the discharged liquid itself Can be further enhanced.

The gist of this pattern forming apparatus is that the ejection control unit makes the droplets and the satellite droplets into spheres having the same diameter.
In a droplet irradiated with laser light during flight, the energy received from the laser light depends on the surface shape irradiated with the laser light, and increases as the irradiation cross-sectional area irradiated with the laser light increases. According to this pattern forming apparatus, the surface shape (irradiation cross-sectional area and shape) irradiated with the laser light can be made equal by making the main droplet and the satellite droplet into spheres having the same diameter. Therefore, the amount of energy from the laser beam received per unit time is approximately equal between the main droplets in flight and the satellite droplets in flight. The drying speed of the liquid body itself can be further increased.

The gist of the pattern forming apparatus is that 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, when the reaction force from the higher evaporation rate to the lower one acts on the droplet, and the reaction force is asymmetric across the droplet and acts excessively on the droplet In that case, the flying curve of the droplet 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. However, by making the intensity distribution of the pair of laser beams equal, it is possible to further 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. 1 is defined 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 (see FIG. 8) provided on the base 11 rotates forward or backward.

  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 a common ink tank 14 via a supply tube 20T, and thereby accommodates the conductive ink Ik from the ink tank 14 and supplies the conductive ink Ik 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 at a predetermined intermediate potential, and a drive signal COM which is a current signal defining the contraction amount, contraction speed, extension amount and extension speed is input. Each time the drive signal COM is input to the piezoelectric element PZ, the piezoelectric element PZ is charged / discharged and contracted and expanded 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 volume and a speed corresponding to the drive signal COM. It is discharged as a liquid column having a tail from the meniscus. In the liquid column ejected in this manner, the tip and rear end of the liquid column are separated during the flight due to a large surface tension acting on the spherical tip and tail. The main droplet Dm is generated by the leading end of the liquid column, and the satellite droplet Ds that follows the main droplet Dm is generated by the trailing end of the liquid column.

  At this time, the meniscus formed in the nozzle N vibrates in response to the displacement of the piezoelectric element PZ that expands and contracts according to the drive signal COM, and generates the liquid column in a shape corresponding to the drive signal COM. In the present embodiment, the drive signal COM generates a liquid column in which the volume of the satellite droplet Ds is close to the volume of the main droplet Dm so that the satellite droplet Ds is superimposed on the landed main droplet Dm. Let The satellite droplets Ds discharged by such a configuration fly in the flight space so as to follow the main droplet Dm, and land so as to be superimposed on the main droplet Dm landed in advance.

Note that the droplets ejected 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 direction. On the other hand, when the resultant force of the external force applied to the droplet acts greatly in the direction crossing the Z direction, the droplet ejected from the nozzle N flies along the path deviating from the target path TL according to the action of the external force, and reaches the landing position. This results in a so-called flight curve, which is a factor that impairs accuracy.

  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. By supplying the first heat quantity q1 and the second heat quantity q2 to the droplets at the timing described above, a desired amount of the 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 a numerical calculation that solves a differential equation related to the above, and a motion equation of the droplet in consideration of 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.

  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 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 showing the optical configuration of the laser irradiation unit 31 mounted on the droplet discharge device 10, and FIG. 6 schematically shows the irradiation angle of the laser beam with respect to each main droplet Dm. FIG.

  As shown in FIG. 5, the laser irradiation unit 31 includes a laser light source 32 as a laser emission unit, a collimating lens 33, a half mirror 34 as a branching unit, and reflection mirrors 35, 36, 37, 38, and 39, 1 laser shaping part 40a and 2nd laser shaping 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 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 is, for example, when a droplet having a relatively large volume is a main droplet Dm and the diameter of the main droplet Dm is 2 rm. , Sin θ ≧ 2 rm / Dx is selected from the range that satisfies the condition. 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 the main droplets Dm ejected simultaneously from the ejection head 15. In addition, when sin θ = 2 rm / Dx is satisfied, there is no gap in the laser beam irradiation direction between the main droplets Dm ejected from the adjacent nozzles N, so that the laser beam that passes through the flight space is eliminated. As a result, the utilization efficiency of laser light is improved.

  The DOEs 42a and 42b are optical components that change the intensity distributions of the first laser beam Le1 and the second laser beam Le2, respectively. The DOEs 42a and 42b are used for the first laser beam Le1 and the second laser beam Le2 in the target path TL of each droplet. The intensity distribution is converted so as to be a flat top hat distribution along the target path TL. Since it is difficult to strictly convert the intensity distribution of such laser light into a desired intensity distribution, the flat intensity distribution that is the top hat type distribution described above is the difference between the maximum intensity and the average intensity, The difference between the minimum intensity and 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.

  When such laser beam energy is absorbed by the flying droplet, the temperature of the droplet rises due to the energy absorbed on the surface of the droplet or inside the droplet. In the case of irradiating a laser beam whose cross-sectional intensity distribution is a Gaussian distribution, the temperature of the droplet immediately after ejection is raised by a low energy region corresponding to the bottom of the Gaussian distribution.

  On the other hand, if the top-hat type laser beam is irradiated as described above, the droplet immediately after ejection is quickly heated to the target temperature (for example, the boiling point of the dispersion medium), and the dispersion medium evaporates. Droplets can fly longer at temperatures that increase efficiency. Moreover, in the case of the discharge form as described above, the conductive ink Ik discharged in a predetermined volume is divided into the main droplet Dm and the satellite droplet Ds having a volume close to the main droplet Dm. In discharging the same volume of the conductive ink Ik, the drying speed of the main droplet Dm and the drying speed of the satellite droplet Ds are made closer. That is, the difference between the drying speed of the main droplet Dm and the drying speed of the satellite droplet Ds is reduced by the amount that the volume of the satellite droplet Ds approaches the main droplet Dm, and the discharged conductive ink Ik itself is dried. Increases speed.

  For example, when the main droplet Dm and the satellite droplet Ds are discharged in a spherical shape, if the diameter of the main droplet Dm is rm and the diameter of the satellite droplet Ds is rs, the volume Vm of the main droplet Dm and the satellite liquid The volume Vs of the droplet Ds is given by the equations (1) and (2), respectively. Further, the total irradiation sectional area S, which is the sum of the irradiation sectional area of the main droplet Dm and the irradiation sectional area of the satellite droplet Ds, is given by Equation (3).

Vm = 4/3 × π × rm ³ (1)
Vs = 4/3 × π × rs ³ (2)
S = π × rm ² + π × rs ² (3)
Then, a condition that the sum of the volume Vm of the main droplet Dm and the volume Vs of the satellite droplet Ds is constant (Vm + Vs = constant), that is, a condition for discharging a certain amount of the conductive ink Ik is applied to the expression (3). Then, the total irradiation sectional area S increases as the volume of the satellite droplet Ds approaches the volume of the main droplet Dm. When rm = rs, that is, when the volume of the satellite droplet Ds is equal to the volume of the main droplet Dm, the total irradiation sectional area S is maximized.

  In addition, when the volume of the main droplet Dm and the volume of the satellite droplet Ds are equal, that is, when rm = rs (= maximum irradiation diameter r), the total volume Va, which is the sum of the volume Vm and the volume Vs. The diameter ra of one droplet Da having the same total volume Va is given by the equations (4) and (5), respectively. Further, a comparative irradiation sectional area Sa, which is an irradiation sectional area of the droplet Da, is given by Expression (6).

Va = 2 × 4/3 × π × rm ³ (4)
ra = 2 ^1/3 × rm (5)
Sa = π × ra ² = 2 ^2/3 × π × rm ² (6)
Since the total irradiation cross section S when the volume Vm and the volume Vs are equal is given by 2 × π × rm ² from the above equation (3), the total irradiation cross section S and the comparative irradiation cross section Sa are By comparison, it can be seen that the total irradiation cross-sectional area is increased by 2/2 ^2/3 times (about 1.26 times) due to the equal volume Vm and volume Vs. Therefore, when the same amount of the conductive ink Ik is ejected, the volume of the satellite droplet Ds approaches the volume of the main droplet Dm, so that the laser beam is efficiently emitted by the increased irradiation cross-sectional area. Absorbed by the conductive ink Ik, the drying efficiency of the conductive ink Ik itself is improved.

  Further, when a droplet that receives laser light during flight evaporates the dispersion medium, the reaction force of the evaporating dispersion medium acts on the surface of the droplet. When the reaction force is not symmetric with respect to the target path TL, the flight bending of the droplet due to the reaction force is induced, and the landing position may be displaced.

  Therefore, the laser irradiation unit 31 described above equally divides the laser intensity P, which is the amount of heat per unit area and unit time, given to the droplets in flight into the first laser beam Le1 and the second laser beam Le2 facing each other. That is, each intensity is set to P / 2. With such an irradiation mode, the evaporation rate of the droplets is symmetric with respect to the target path TL, and the reaction forces accompanying the evaporation of the dispersion medium cancel each other, so that the flying curvature of the droplets hardly occurs, and the main droplets The positional deviation of the landing position of Dm is suppressed. In addition, if the discharge mode is as described above, there is a difference between the reaction force received by the main droplet Dm and the reaction force received by the satellite droplet Ds by the amount that the volume of the satellite droplet Ds approaches the main droplet Dm. Get smaller. That is, the flight path of the satellite droplet Ds is brought close to the flight path of the main droplet Dm, and the satellite droplet Ds is easily superimposed on the main droplet Dm after landing. Therefore, since both the main droplet Dm and the satellite droplet Ds land at substantially the same position, the contamination of the drawing surface GSa by the droplet that has bent in flight is suppressed. Moreover, even if both sides have a flight curve, the relative landing positions are maintained, and these can be superimposed.

  Further, when a droplet that has reached the target temperature receives laser light, if the amount of energy applied to the droplet exceeds the heat of vaporization of the dispersion medium that is an evaporation component, the droplet rises to the boiling point of the conductive ink Ik. Since the liquid medium is heated, evaporation of the dispersion medium is started also from the inside of the droplet, and bumping of the droplet is likely to occur.

Therefore, the laser irradiation unit 31 described above adjusts the laser intensity P so as to give the total energy E that is the sum of the first heat quantity q1 and the second heat quantity q2 to the droplets in flight. . With such a laser intensity P, the temperature of the droplet rises to a higher temperature, for example, the boiling point of the dispersion medium, from the temperature range in which droplet bumping can be suppressed, and this temperature state is maintained. As a result, a stable evaporation state is maintained while the bump boiling of the droplet is suppressed, and the drying speed of the droplet is increased by the length of the period during which the droplet temperature is the target temperature.

  Note that the laser intensity P as described above is, for example, a level within a laser intensity at which droplets in flight are irradiated with laser beams having different intensities and the flight state of the droplets is imaged with a high-speed camera. Can be obtained directly by selecting the highest value from. Further, the above-described platen gap PG and droplet flight speed v can be simply estimated by applying the equation (7). The flight period t in the equation (7) is a period during which the discharged droplets fly, and is obtained by the flight period t = PG / v using the flight speed v of the droplets and the platen gap PG. 2r in the equation (7) is the diameter of the droplet, and PG × 2r in the equation (7) is an irradiation cross-sectional area of the laser beam with respect to the droplet in flight.

P = E / ((PG × 2r) × t) (7)
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, and various data and various controls stored in the ROM 52 and the RAM 53. According to the program, the carrying process of the stage 12 and the carriage 16, the droplet ejection process of the ejection head 15, the laser beam emission process of the laser light source 32, etc. 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 a drive waveform, an external I / F 56 that receives various signals, and an internal that transmits and receives various signals. I / 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 voltage waveform supplied to the piezoelectric element PZ, and the volume of the satellite droplet Ds is set so that the satellite droplet Ds is superimposed on the main droplet Dm after landing. This data is set based on various droplet ejection experiments, numerical calculations, and the like in order to approach the volume 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 beam having the laser intensity P to the laser irradiation unit 31 described above.

  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 executed, 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, so that the address The waveform data stored in is read out. The drive waveform generation circuit 55 generates voltage level data based on the read waveform data, and drives a current signal corresponding to the voltage signal using the voltage signal obtained by converting the voltage level data into an analog signal and amplifying the voltage signal. Output as signal COM.

  When a 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 begins to enter immediately below the nozzle N, and in response to the control signal, the laser light source 32 has the above laser intensity P. A laser beam 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. When the dot pattern data is generated, the control unit 51 serially transfers the dot pattern data to the head drive circuit 61 using the transfer clock CLK as a synchronization signal. In the present embodiment, the serial data generated using 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 end of each switch element, and the output end of each switch element. A corresponding piezoelectric element PZ is connected to each. Each switch element outputs a drive signal COM to the corresponding piezoelectric element PZ in accordance with an open / close signal associated with the corresponding piezoelectric element PZ.

  According to the head driving circuit 61 having such a configuration, each time the timing signal LAT is input, that is, every time the lattice point T is located immediately below the nozzle N, the piezoelectric element PZ is selected based on the dot pattern data. The drive signal COM is output to the piezoelectric element PZ. 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 is a diagram showing a waveform of a voltage signal generated by the drive waveform generation circuit 55 to generate the drive signal COM, and FIG. 10 is a diagram schematically showing a discharge state corresponding to the drive signal COM.

  As shown in FIG. 9, the waveform of the voltage signal corresponding to the drive signal COM includes a first waveform portion 71 that raises the voltage level from the reference potential V0 to the first potential V1, and a voltage level from the first waveform portion 71. And a third waveform portion 73 for lowering the voltage level from the second waveform portion 72 to the second potential V2. The waveform of the voltage signal corresponding to the drive signal COM is from the third waveform portion 73 to the fourth waveform portion 74 that holds the voltage level, and from the fourth waveform portion 74 to the third potential V3 that is lower than the reference potential V0. A fifth waveform portion 75 for decreasing the voltage level, a sixth waveform portion 76 for maintaining the voltage level from the fifth waveform portion 75, and a seventh waveform for increasing the voltage level from the sixth waveform portion 76 to the reference potential V0. Part 77.

When such a drive signal COM is supplied to the piezoelectric element PZ, the piezoelectric element PZ contracts due to the current signal corresponding to the first waveform portion 71, whereby the volume of the cavity 22 expands from the initial state, and the conductive ink Ik is introduced into the cavity 22. Next, the piezoelectric element PZ is held in a contracted state by a current signal corresponding to the second waveform portion 72, and thus the volume of the cavity 22 is held in an expanded state. Then, the phase of the meniscus vibration generated by the volume expansion of the cavity 22 is adjusted. Subsequently, the third waveform portion 73 expands the piezoelectric element PZ from the contracted state at the timing adjusted by the second waveform portion 72, and thereby the third waveform portion reaches the volume corresponding to the voltage level of the second potential V2. The volume of the cavity 22 is reduced at a speed corresponding to the inclination of 73, and the conductive ink Ik in the cavity 22 is pressurized. Then, the meniscus subjected to such pressurization is pushed out from the nozzle N, and at the end of the third waveform portion 73, as shown in FIG. 10A, an ink column 78 having a hemispherical tip is formed in the nozzle N. Formed from.

  Next, the piezoelectric element PZ holds the state for the period of the fourth waveform portion 74 by the current signal corresponding to the fourth waveform portion 74, and thereby the volume of the cavity 22 is held. At this time, the conductive ink Ik in the cavity 22 that has flowed due to the pressurization of the third waveform portion 73 in the previous stage can be prevented from flowing to the ink column. On the other hand, the meniscus at the tip of the ink column continues to move in the ejection direction due to the inertial force during the pressurization of the third waveform portion 73 at the previous stage. As a result, at the end of the fourth waveform portion 74, as shown in FIG. 10B, an ink column 78 having a thick tip and a thin base end is formed.

  Next, the piezoelectric element PZ is expanded again by the current signal corresponding to the fifth waveform portion 75, whereby the volume of the cavity 22 is increased at a speed corresponding to the inclination of the fifth waveform portion 75 up to the volume corresponding to the voltage level of the third potential V3. Is reduced, and the conductive ink Ik in the cavity 22 is pressurized again. Then, the meniscus subjected to such pressurization is further pushed out from the nozzle N, and at the end of the fifth waveform portion 75, as shown in FIG. 10C, it is connected to the ink column 78 formed in advance. A new ink column 79 is formed.

  Next, the piezoelectric element PZ holds the state for the period of the sixth waveform portion 76 by the current signal corresponding to the sixth waveform portion 76, and thereby the volume of the cavity 22 is held. At this time, the conductive ink Ik in the cavity 22 that has been flowing due to the pressurization of the fifth waveform portion 75 in the previous stage can be prevented from flowing to the ink column, and the peripheral vibration of the nozzle N due to residual vibration accompanying this. The meniscus is drawn back to the nozzle N. On the other hand, the meniscus at the tip of the ink column continues to move in the ejection direction due to the inertial force during the pressurization of the fifth waveform portion 75 in the previous stage. As a result, at the end of the sixth waveform portion 76, as shown in FIG. 10D, an ink column 79 having a thick tip end and a narrow base end is formed.

  Next, the piezoelectric element PZ contracts due to a current signal corresponding to the seventh waveform portion 77 inputted at a timing opposite to the vibration of the conductive ink Ik in the cavity 22 and the meniscus, thereby expanding the volume of the cavity 22. The volume of the cavity 22 is restored to the initial state. As a result, the base end portion of the ink column 79 is separated from the nozzle N as shown in FIG. Then, as shown in FIG. 10 (f), each of the ink columns 78 and 79 is split by the surface tension to form a sphere and fly as a main droplet Dm and a satellite droplet Ds. It should be noted that the seventh waveform portion 77 is input at a timing opposite to the phase of the oscillation of the conductive ink Ik in the cavity 22 and the meniscus, whereby the cavity 22 and the satellite droplet Ds accompanying the ejection of the main droplet Dm and the satellite droplet Ds described above. Residual vibration in the meniscus can be damped.

As described above, the flight speed and the volume of the main droplet Dm and the satellite droplet Ds are determined based on the voltage level of the fourth waveform portion 74 that forms the boundary between the ink columns 78 and 79 and the first and second ink columns 78 and 79. It depends on the inclinations of the third waveform portion 73 and the fifth waveform portion 75. Therefore, in the waveform of the voltage signal corresponding to the drive signal COM of the present embodiment, the flight speed and volume of the satellite droplet Ds and the flight of the main droplet Dm so that the satellite droplet Ds is superimposed on the main droplet Dm after landing. In order to make the velocity and the volume equal, the voltage level of the fourth waveform portion 74 and the slopes of the third waveform portion 73 and the fifth waveform portion 75 are set.

  The voltage level of the fourth waveform portion 74 and the inclination of the third waveform portion 73 and the fifth waveform portion 75 can be determined by directly observing the flight state and landing state of the main droplet Dm and the satellite droplet Ds. it can. 11 and 12 show observation results of an experiment conducted to determine the voltage level of the fourth waveform portion 74 under the irradiation mode described above. FIG. 11 shows the main droplet Dm and the satellite droplet. It is the figure which showed typically the landing situation with Ds. FIG. 12 is a diagram showing the relationship between the positional deviation amount, which is the distance between the landed main droplet Dm and the satellite droplet Ds, and the volume of the satellite droplet Ds. FIG. 11 shows the landing situation when the voltage level of the fourth waveform portion 74 gradually increases from the third potential V3 to the second potential V2 from the left side to the right side in the drawing.

  As shown in FIG. 11, when the voltage level of the fourth waveform portion 74 is substantially equal to the third potential V3, that is, when the boundary between the ink columns 78 and 79 disappears, the main droplet Dm has a narrow and long tail. As a result, the satellite droplet Ds is generated which is significantly smaller than the main droplet Dm. Such small satellite droplets Ds are easily bent by receiving laser light, and as shown in FIGS. 11 and 12, the landing position of the main droplet Dm and the landing position of the satellite droplet Ds are the same. The amount of deviation will be increased.

  On the other hand, when the voltage level of the fourth waveform portion 74 is close to the second potential V2, the volume of the satellite droplet Ds is close to the volume of the main droplet Dm. The dry state comes closer to the main droplet Dm. That is, the flight trajectory of the satellite droplet Ds is close to the flight trajectory of the main droplet Dm. As a result, as shown in FIGS. 11 and 12, the landing position of the main droplet Dm and the landing position of the satellite droplet Ds are close, and the voltage level of the fourth waveform portion 74 becomes the second potential V2. In this case, the volume and the flight speed are substantially equal between the main droplet Dm and the satellite droplet Ds, and landing is performed so that substantially the entire satellite droplet Ds is superimposed on the main droplet Dm after landing. Therefore, by adopting such a voltage level as the voltage level of the fourth waveform portion 74, the volume of the satellite droplet Ds is reduced so that the main droplet Dm after landing and the satellite droplet Ds overlap. It becomes possible to approach the volume of Dm.

  In the above-described discharge mode, since the satellite droplet Ds is generated later than the main droplet Dm, there is a time difference between the timing at which the satellite droplet Ds lands and the timing at which the main droplet Dm lands. Occurs. On the other hand, since the stage 12 continues to move between the timing at which the main droplet Dm lands and the timing at which the satellite droplet Ds lands, the landing position of the satellite droplet Ds is equivalent to the time difference described above. It will shift in the moving direction of the stage 12 with respect to the landing position of the main droplet Dm. However, in the above-described droplet discharge device, the flight speed of the main droplet Dm and the satellite droplet Ds is sufficiently higher than the moving speed of the stage 12 in the first place, and the flight period of the main droplet Dm and the satellite droplet Ds. However, since the time difference is sufficiently longer than the above-described time difference, the positional deviation of the landing position of the satellite droplet with respect to the main droplet that has landed in advance can be very small. Therefore, the satellite droplets Ds can be superimposed and landed on the landed main droplet Dm, and the pattern shape accuracy can be improved.

Note that, when the voltage level of the fourth waveform portion 74 is raised to the first potential V1 side from the second potential V2, the volume of the main droplet Dm becomes smaller than the volume of the satellite droplet Ds. As shown in FIG. 12, the flight bend occurs in the main droplet Dm. The flight bend of the main droplet Dm increases as the volume of the main droplet Dm decreases, in other words, the volume of the satellite droplet Ds increases, and the position of the landing position of the satellite droplet Ds with respect to the landing position of the main droplet Dm. The amount of deviation increases. Therefore, when determining the voltage level of the fourth waveform portion 74, as shown in FIG. 12, it corresponds to a range A in which a displacement amount smaller than a predetermined displacement amount L is obtained based on a predetermined design rule. It is preferable to select a voltage level at which satellite droplets Ds having a volume to be discharged are ejected.

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-described embodiment, the main droplet Dm and the satellite droplet Ds are formed into a spherical shape having the same volume, so that the first and The irradiation sectional area irradiated with the second laser beams Le1 and Le2 can be increased, and the drying speed of each droplet can be improved.

  (2) Further, the flight bending of both the main droplet Dm and the satellite droplet Ds is suppressed, and these can be landed by being superimposed on the drawing surface GSa, and the pattern shape accuracy can be improved.

  (3) According to the above-described embodiment, by equalizing the flight speeds of the main droplet Dm and the satellite droplet Ds, it is possible to equalize the irradiation time during which each droplet is irradiated with laser light. That is, the energy received by each droplet from the first and second laser beams Le1 and Le2 can be made equal, and each droplet can be landed on the drawing surface GSa under the same dry state.

  (4) By irradiating each droplet with the first and second laser beams Le1 and Le2 which are a pair of laser beams opposed to each other, the flight bending of each droplet is suppressed, and the lattice of the main droplet Dm It is also possible to suppress the displacement of the landing position with respect to the point T.

  (5) According to the embodiment described above, the drying efficiency of the main droplets Dm and the satellite droplets Ds can be further increased by making the intensity distribution of the first and second laser beams Le1 and Le2 into a top-hat distribution. .

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 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, the main droplet Dm and the satellite droplet Ds are ejected from each nozzle N of the ejection head 15 at different ejection timings, so that laser light is irradiated to all the droplets. Become.

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 embodiment described above, the laser light applied to the main droplet Dm and the satellite droplet Ds 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 these droplets 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 potential waveform corresponding to the drive signal COM equalizes the flight speed of the main droplet Dm and the flight speed of the satellite droplet Ds. However, the flight speed may be different. That is, if the satellite droplet Ds has a volume close to the volume of the main droplet Dm so that the satellite droplet Ds overlaps the main droplet Dm after landing, the flying speed of each droplet is different. Also good. Even in such a configuration, since the volume of the satellite droplet Ds is brought close to the volume of the main droplet Dm, the same effect as in the above embodiment can be obtained.

  In the above embodiment, the main droplet Dm and the satellite droplet Ds have a spherical shape, but the droplets may have a columnar shape. Even in such a configuration, since the volume of the satellite droplet Ds is brought close to the volume of the main droplet Dm, the same effect as in the above embodiment can be obtained.

  In the above embodiment, as shown in FIG. 9, the voltage waveform indicating the potential level of the third potential V3 lower than the reference potential V0 is used, so that the main droplet Dm and the satellite droplet Ds are used. Flight speed and volume are equal. For example, as shown in FIG. 13, the first to third potentials V <b> 1 are not limited to such a potential level, and the voltage waveform that makes the flight speed and volume equal between the main droplet Dm and the satellite droplet Ds. A voltage waveform in which .about.V3 becomes higher than the reference potential V0 is also applicable.

  In the above embodiment, an aqueous dispersion medium is used as the liquid dispersion medium. In addition, a surfactant may be added to the dispersion medium in order to adjust the surface tension of the liquid. . According to such a dispersion medium, it is possible to adjust the surface tension at the meniscus by changing the addition amount of the surfactant, and the degree of freedom of the voltage waveform corresponding to the drive signal COM can be expanded.

  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 shows an example of the pattern formation apparatus in this embodiment. The perspective view which shows an ejection head. FIG. 3 is a main part cross-sectional view showing the inside of the ejection head. The schematic diagram which shows the dot pattern lattice of a green sheet. FIG. 3 is a schematic diagram showing an optical system of a droplet discharge device. The schematic diagram for demonstrating the relationship between a laser beam and a droplet. The block circuit diagram which shows the electric constitution of a droplet discharge apparatus. The block circuit diagram which shows the electric constitution of a head drive circuit. The figure which shows the voltage waveform corresponding to a drive signal. (A)-(f) The figure which shows typically the discharge condition according to a drive signal similarly. The figure which shows typically the landing condition of the main droplet and a satellite droplet. The graph which shows the relationship between the volume of a satellite droplet, and positional offset amount. The figure which shows the voltage waveform corresponding to the drive signal in the example of a change.

Explanation of symbols

  θ: inclination angle, A: range, E: total energy, L: displacement, N: nozzle, P: laser intensity, S: total irradiation cross section, T: lattice points, t: flight period, v ... flight speed , CE ... carriage encoder, CM ... carriage motor, Da ... droplet, DL ... dot pattern lattice, Dm ... main droplet, Ds ... satellite droplet, Dx ... nozzle pitch, Dy ... discharge pitch, GS ... green sheet, Ia ... Drawing information, Ik ... Conductive ink, Le ... Basic laser light, PG ... Platen gap, PI ... Parallel pattern data, PZ ... Piezoelectric element, q1 ... First heat quantity, q2 ... Second heat quantity, ra ... Diameter, Sa ... Comparative irradiation cross section, SE ... stage encoder, SI ... serial pattern data, SM ... stage motor, TL ... target path, V0 ... reference potential, V1 ... first potential, V2 ... second potential, V ... 3rd potential, Va ... Total volume, Vm ... Volume, Vs ... Volume, CLK ... Transfer clock, COM ... Drive signal, GSa ... Drawing surface, LAT ... Timing signal, Le1 ... First laser beam, Le2 ... Second laser Light, 56 ... External I / F, 57 ... Internal I / F, 10 ... Droplet discharge device, 11 ... Base, 12 ... Stage, 13 ... Guide member, 14 ... Ink tank, 15 ... Discharge head, 16 ... Carriage , 17 ... Head substrate, 17a ... Connection terminal, 20 ... Head 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 ... Reflecting mirror 36 ... Reflecting mirror 40a ... First laser forming part 40b ... Second laser forming part 41a ... Siri Cylindrical lens, 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, 58 ... On Output 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 generator 65 ... Level shifter 66 ... Piezoelectric element Switch, 71 ... 1st waveform portion, 72 ... 2nd waveform portion, 73 ... 3rd waveform portion, 74 ... 4th waveform portion, 75 ... 5th waveform portion, 76 ... 6th waveform portion, 77 ... 7th waveform portion 78 ... ink column, 79 ... ink column.

Claims (4)

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 in the pressure chamber; and a nozzle that communicates with the pressure chamber. An ejection head for ejecting toward a drawing 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
A pattern forming apparatus that performs control so that the volume of satellite droplets generated as the droplets are discharged is the same as the volume of the droplets. The discharge controller is
The pattern forming apparatus according to claim 1, wherein control is performed such that a speed at which the satellite droplets are discharged is the same as a speed at which the droplets are discharged. The discharge controller is
The pattern forming apparatus according to claim 1, wherein the droplets and the satellite droplets are spheres having the same diameter. The laser irradiation unit is
The pattern formation apparatus of any one of Claims 1-3 which irradiate a pair of laser beam which opposes the said space.

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