JP2005069900A - Focusing-point position detecting method, focusing-point position detector, droplet observing method, droplet observing device, and droplet discharging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a focusing-point position detecting method and a focusing-point position detector for accurately, rapidly, and easily detecting a focusing-point position of laser beams by a simple structure, to provide a droplet observing method and a droplet observing device for accurately and easily observing a droplet discharged from a droplet discharging head, and to provide a droplet discharging device. <P>SOLUTION: This focusing-point position detector 3 is equipped with a light screening plate 4 having a pin hole 41 on an optical axis Ax of a focusing lens 27, a linear motor 11 for moving the screening plate 4 in the direction of the optical axis Ax, a linear encoder 12 for detecting the position of the screening plate 4, light receiving elements 71 and 72 for receiving the laser beams 233 and 234, and a focusing-point position detecting means for detecting the positions of a focusing point C of the laser beams 233 and 234 based on output signals of the receiving elements 71 and 72 and on positional information on the screening plate 4 detected by the linear encoder 12 with the screening plate 4 moved in the direction of the optical axis Ax by actuating the linear motor 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a condensing point position detection method, a condensing point position detection device, a droplet observation method, a droplet observation device, and a droplet discharge device.

For example, a liquid crystal display device such as a color filter or an organic EL display device is manufactured by ejecting droplets onto a substrate using a droplet ejection head of the same type as an inkjet head of an inkjet printer, or a metal wiring is formed on the substrate. Industrial droplet discharge devices that can be used to form the
When manufacturing using such a droplet discharge device, it is necessary to observe the flight speed, volume, etc. of the droplet discharged from the droplet discharge head in order to determine the driving conditions of the droplet discharge head, etc. There is. Conventionally, the droplet is observed by irradiating a laser beam so as to intersect the trajectory of the droplet, and based on an output signal of a light receiving element that receives the laser beam (for example, see Patent Document 1). ). In this method, it is necessary to accurately grasp the condensing point position of the laser light, the distance between the light receiving elements, etc., and to align them at the correct position.

  However, conventionally, this alignment method has not been established, and generally, since it has been adjusted to a rough position manually and calculated based on a theoretical value, there has been a problem that an error is large. As a result, it was difficult to perform observation with high accuracy. Further, in the case of a droplet discharge head having a plurality of nozzle rows, if the row to be observed changes, it is necessary to change various parameters, and the observation procedure is complicated.

JP-A-5-248899

  The objective of this invention is providing the condensing point position detection method and condensing point position detection apparatus which can detect the condensing point position of a laser beam correctly, rapidly and easily by simple structure. Furthermore, an object of the present invention is to provide a droplet observation method, a droplet observation device, and a droplet discharge device capable of accurately and easily observing a droplet discharged from a droplet discharge head.

Such an object is achieved by the present invention described below.
The condensing point position detecting method of the present invention is a condensing point position detecting method for detecting the condensing point position of the laser light transmitted through the condensing lens,
A light shielding plate having a pinhole or a slit on the optical axis of the condenser lens is moved along the optical axis direction of the condenser lens, and is disposed on the optical path of the laser light and at the tip of the light shielding plate. An output signal of the light receiving means is detected, and the condensing point position is detected based on the output signal and the position of the light shielding plate.
Thereby, the condensing point position detection method which can detect the condensing point position of a laser beam correctly, quickly and easily with a simple structure can be provided.

The condensing point position detecting device of the present invention is a condensing point position detecting device for detecting the condensing point position of the laser light transmitted through the condensing lens,
A light shielding plate having a pinhole or slit on the optical axis of the condenser lens;
Moving means for moving the light shielding plate along the optical axis direction of the condenser lens;
Position detecting means for detecting the position of the light shielding plate in the optical axis direction;
A light receiving means arranged on the tip of the light shielding plate on the optical path of the laser light and photoelectrically converting the received light;
The light condensing is performed based on the output signal of the light receiving means and the position information of the light shielding plate detected by the position detecting means in a state where the moving means is operated to move the light shielding plate in the optical axis direction. And a condensing point position detecting means for detecting a point position.
Thereby, the condensing point position detection apparatus which can detect the condensing point position of a laser beam correctly, quickly and easily with a simple structure can be provided.
In the condensing point position detecting apparatus according to the present invention, it is preferable that the condensing point position detecting unit determines the position of the light shielding plate when the amount of light received by the light receiving unit is maximized as the condensing point position.
Thereby, the position of a condensing point can be detected more correctly.

The droplet observation method of the present invention irradiates at least one laser beam that has passed through a condenser lens so as to intersect the trajectory with respect to the trajectory of a droplet ejected from a nozzle hole of a droplet ejection head and flying. A droplet observation method for observing flying droplets based on an output signal of a light receiving means that receives the laser beam,
The present invention is characterized in that information on flying droplets is obtained in consideration of the information on the condensing point position of the laser beam detected using the condensing point position detecting method of the present invention.
Thereby, it is possible to provide a droplet observation method capable of accurately and easily observing droplets ejected from the droplet ejection head.

The droplet observation method of the present invention is a droplet observation method for measuring the flight speed of a droplet ejected from a nozzle hole of a droplet ejection head and flying.
The two laser beams transmitted through the condenser lens intersect with each other on the optical axis of the condenser lens, and then irradiate the two laser lights so as to intersect with the droplet trajectory, respectively. The laser beam of the book is received by the light receiving means,
Finding the distance between the intersection and the trajectory based on the intersection position of the two laser beams detected using the condensing point position detection method of the present invention,
Based on the distance, calculate the distance between two intersections of the two laser beams and the ballistic path,
Obtaining information on the flight speed of the droplet based on the distance between the intersections and the time difference of the output signal change of the light receiving means when the droplet intercepts the two laser beams in order. To do.
Thereby, the flight speed of the droplet can be observed accurately and easily.

The droplet observation device of the present invention is a droplet observation device for observing a droplet ejected from a nozzle hole of a droplet ejection head and flying,
Laser light irradiation means for irradiating at least one laser light transmitted through the condenser lens so as to intersect the trajectory of the droplet;
A condensing point position detecting device of the present invention for detecting the condensing point position of the laser beam;
A light receiving means for receiving the laser beam and performing photoelectric conversion;
Droplet observation means for obtaining information on flying droplets based on the output signal of the light receiving means,
The droplet observing means obtains information on flying droplets by taking into account information on the condensing point position of the laser beam detected using the condensing point position detecting device.
Accordingly, it is possible to provide a droplet observation device that can accurately and easily observe the droplets ejected from the droplet ejection head.

A droplet discharge device of the present invention includes a droplet discharge head that discharges a droplet toward a workpiece,
It is provided with the droplet observation device of the present invention which observes the droplet discharged from the nozzle hole of the droplet discharge head and flying.
Accordingly, it is possible to provide a droplet discharge device having a function capable of accurately and easily observing droplets discharged from the droplet discharge head.

Hereinafter, a condensing point position detection method, a condensing point position detection device, a droplet observation method, a droplet observation device, and a droplet discharge device according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
1 is a side view showing an embodiment of a condensing point position detecting device of the present invention, FIG. 2 is a side view showing a laser beam irradiation means, FIG. 3 is a cross-sectional view taken along line AA in FIG. -B line sectional view and CC line sectional view, FIG. 4 is a side view showing a state where the focal point position is detected in the focal point position detecting device shown in FIG. 1, and FIG. 5 and FIG. FIG. 7 is a front view showing a light shielding plate in the condensing point position detecting device shown in FIG. 1, and FIG. 7 is a functional block diagram of the condensing point position detecting device (droplet discharge device) of the present invention. Note that hatched portions in FIGS. 5 and 6 represent regions irradiated with laser light.

The condensing point position detection device 3 shown in FIG. 1 detects the position of the condensing points (intersection points) C of the laser beams 233 and 234 that have passed through the condensing lens 27. First, the laser beam irradiation means 2 that irradiates the laser beams 233 and 234 will be described.
As shown in FIGS. 1 and 2, the laser beam irradiation means 2 includes a laser beam irradiation unit 21 that irradiates a single laser beam 23, and a beam splitter that branches the laser beam 23 into a laser beam 231 and a laser beam 232. (Prism) 25, laser blade 26 that shields a part of each of laser beams 231 and 232, and condenser lens 27.
The type of the laser beam irradiation unit 21 is not particularly limited, and for example, a gas laser such as a Ne—He laser, an Ar laser, or a CO ₂ laser, a solid laser such as a ruby laser, a YAG laser, or a glass laser, or a semiconductor laser is used. be able to.

  As shown in FIG. 3A, the laser light 23 emitted from the laser light irradiation unit 21 has a substantially circular cross section. When the laser beam 23 passes through the beam splitter 25, it is branched into a pair of laser beams 231 and 232 that are parallel to each other. As shown in FIG. 3B, the cross sections of the laser beams 231 and 232 are almost semicircular. When the laser beams 231 and 232 pass through the laser blade 26, the upper portion of the laser beam 231 is shielded from light, and the lower portion of the laser beam 232 is shielded from light. As a result, as shown in FIG. 3C, laser beams 233 and 234 having an elongated cross section are obtained. In other words, the laser beams 233 and 234 are band-shaped light beams.

As shown in FIG. 1, the laser beams 233 and 234 in a parallel state are incident on the condensing lens 27, refracted, and intersect at a condensing point C. The condensing point position detection device 3 detects the position of such a condensing point C.
In the illustrated configuration, since the laser beams 233 and 234 before entering the condenser lens 27 are parallel to each other, the position of the condensing point C coincides with the focal position of the condenser lens 27. When the laser beams 233 and 234 before entering the condensing lens 27 are not parallel to each other, the position of the condensing point C is shifted to the condensing lens 27 side or the opposite side from the focal position of the condensing lens 27. It becomes the position.

  The condensing point position detection device 3 includes a light shielding plate 4 having a pinhole (small hole) 41 on the optical axis Ax of the condensing lens 27, and a linear motor (movement) that moves the light shielding plate 4 along the optical axis Ax direction. Means) 11, a linear encoder (position detecting means) 12 for detecting the position of the light shielding plate 4 in the optical axis Ax direction, light receiving elements (light receiving means) 71 and 72 for receiving the laser beams 233 and 234 and photoelectrically converting them. It has.

  The light shielding plate 4 is a flat member. The light shielding plate 4 has an installation height adjusted in advance so that the position of the pinhole 41 coincides with the optical axis Ax. Moreover, it is preferable that the surface of the light shielding plate 4 on the side irradiated with the laser beams 233 and 234 is subjected to a scattering process for scattering light. Thereby, the reflected light of the laser beams 233 and 234 is prevented from traveling in a specific direction, and the safety of the operator can be ensured.

The light shielding plate 4 is movable in the direction of the optical axis Ax by driving the linear motor 11. The moving means for moving the light shielding plate 4 is not limited to the linear motor 11 and may be any device, for example, a ball screw and a servo motor for rotating the ball screw.
The linear motor 11 operates based on the control of the control means 6 (see FIG. 7). The control means 6 has a CPU (Central Processing Unit) 61 and a storage unit 62. The storage unit 62 includes a storage medium (recording medium) that can be read by the CPU 61, and the storage medium includes a magnetic or optical recording medium, a semiconductor memory, or the like.

The position of the light shielding plate 4 in the optical axis Ax direction is detected by the linear encoder 12. The detection signal of the linear encoder 12 is input to the control means 6. Note that the position detecting means of the light shielding plate 4 is not limited to the linear encoder 12, and may be any device, for example, a laser length measuring device.
As shown in FIG. 1, the light receiving element 71 is disposed at the tip of the light shielding plate 4 on the optical path of the laser beam 233. The light receiving element 72 is disposed on the optical path of the laser beam 234 and ahead of the light shielding plate 4. Signals output from the light receiving elements 71 and 72 are input to the control means 6.

In the condensing point position detecting device 3 of the present embodiment, the control unit 6 functions as a condensing point position detecting unit. The control means 6 detects the position of the condensing point C as follows.
The condensing point position detection device 3 starts the operation of detecting the position of the condensing point C from the state shown in FIG. In the state of FIG. 1, the light shielding plate 4 is located relatively far from the condenser lens 27. Thereby, in the state of FIG. 1, since the laser beams 233 and 234 are blocked by the light shielding plate 4, the light receiving elements 71 and 72 do not receive the laser beams 233 and 234.

  From the state of FIG. 1, the control means 6 operates the linear motor 11 to move the light shielding plate 4 in a direction approaching the condenser lens 27. When the light shielding plate 4 moves to the position shown in FIG. 4, the laser beams 233 and 234 pass through the pinhole 41 and are received by the light receiving elements 71 and 72. In this state, the position of the light shielding plate 4 (pinhole 41) matches the position of the condensing point C. Therefore, the control means 6 detects that the laser beams 233 and 234 are received by the light receiving elements 71 and 72 based on the output signals, and the optical axis Ax of the light shielding plate 4 detected by the linear encoder 12 at that time. The direction position is determined to be the position of the condensing point C. In this way, the control means 6 can detect the position of the condensing point C.

In addition, after the laser beams 233 and 234 are received by the light receiving elements 71 and 72, the control means 6 moves the position of the light shielding plate 4 little by little to the left and right in the drawing so that the light receiving amounts of the light receiving elements 71 and 72 are increased. The maximum position may be detected, and the position may be determined as the position of the condensing point C. Thereby, the position of the condensing point C can be detected more accurately.
In addition, when the detection operation of the position of the condensing point C is started, the light shielding plate 4 may be moved in the direction away from the position where the light shielding plate 4 is close to the condensing lens 27 contrary to the above. Good.

According to the condensing point position detection device 3 of the present invention as described above, the position of the condensing point C of the laser beams 233 and 234 can be detected accurately, easily and quickly. In the present invention, the above-mentioned effect can be achieved by the condensing point position detecting device 3 having a simple structure.
In the present embodiment, the two light receiving elements 71 and 72 are installed as the light receiving means, but only one of them may be installed. Further, the light receiving means is not limited to the light receiving element, and for example, an imaging element such as a CCD (Charge Coupled Device) may be used.

In this embodiment, the position of the condensing point C, which is the intersection of the two laser beams 233 and 234 having a relatively thin light beam, is detected. However, in the present invention, the collection of the laser beam having a relatively thick light beam is detected. It is also possible to detect the position of the light spot (focal point).
In the illustrated configuration, the light receiving elements 71 and 72 are disposed at positions shifted from the optical axis Ax, but may be disposed on the optical axis Ax.
In addition, instead of the pinhole 41, the light shielding plate 4 may be formed with a slit that extends along the direction perpendicular to the paper surface of FIG. 1 through the optical axis Ax. Thus, the position of the condensing point C can be detected.

FIG. 8 is a side view showing an embodiment of the droplet observation device and the droplet discharge device of the present invention.
The droplet discharge device 1 shown in FIG. 8 includes a droplet discharge head 9 and a droplet observation device 5 that observes a droplet 100 that is discharged from a nozzle hole 92 of the droplet discharge head 9 and flies. . First, the droplet discharge head 9 will be described.
As shown in FIGS. 1 and 2, the droplet discharge head (inkjet head) 9 has a nozzle surface 91 on the lower surface side, and a plurality of nozzle holes 92 are arranged in three rows on the nozzle surface 91. Is formed. That is, although three nozzle holes 92 appear in FIG. 8, many nozzle holes 92 are formed side by side in a direction perpendicular to the paper surface of FIG. The number of nozzle hole rows is not limited to 3, but may be 2 rows or less or 4 rows or more.
Each nozzle hole 92 is provided with a pressure chamber (cavity) 93 communicating with the nozzle hole 92 and an actuator (not shown) for changing the pressure of the liquid filled in the pressure chamber 93. It has been.

  The droplet discharge head 9 is driven by the head driving unit 13. The head drive unit 13 supplies a drive signal to the actuator of the droplet discharge head 9 based on the control of the control unit 6. When a drive signal is energized to the actuator, the actuator is operated to change the pressure of the liquid in the pressure chamber 93, and as a result, the liquid in the pressure chamber 93 drops downward from the nozzle hole 92 to the droplet 100. Are discharged. The actuator of the droplet discharge head 9 is not particularly limited, and for example, a piezo actuator or an electrostatic actuator can be used. The droplet discharge head 9 may be a film boiling type ink jet head using a heater that generates bubbles by heating a liquid as an actuator.

  The liquid (including the dispersion liquid) discharged by the droplet discharge head 9 is not particularly limited. For example, ink, a filter material for a color filter, and a fluorescent material for forming an EL light emitting layer in an organic EL device. In order to form a fluorescent material for forming a phosphor in a PDP apparatus, an electrophoretic material for forming an electrophoretic body in an electrophoretic display device, a bank material for forming a bank on the surface of a substrate, various coating materials, and an electrode Liquid electrode material, particle material constituting spacer for forming a minute cell gap between two substrates, liquid metal material for forming metal wiring, lens material for forming microlens, resist material Any liquid such as a light diffusing material for forming a light diffuser may be used.

  The droplet discharge device 1 includes, for example, a work table (not shown) that holds a work such as various substrates such as a glass substrate, a silicon substrate, a flexible substrate, and an optical member such as a lens, and the work table and the droplet discharge head 9. And a moving mechanism (not shown) that relatively moves in two directions orthogonal to each other. Then, the droplet discharge device 1 operates this moving mechanism based on the control of the control means 6, and the droplet discharge head 9 and the work table with one of the two directions as the main scanning direction and the other as the sub-scanning direction. A predetermined pattern can be drawn on the work by ejecting the droplet 100 from each nozzle hole 92 toward the work on the work table while relatively moving.

The droplet observation device 5 is a device that observes the flight speed of the droplet 100 ejected from the nozzle hole 92 of the droplet ejection head 9. The liquid droplet observation device 5 is a liquid droplet observation device that obtains information on the flight speed of the liquid droplet 100 based on the output signals of the laser beam irradiation means 2 and the light condensing point position detection device 3 and the light receiving elements 71 and 72 described above. And. In FIG. 8, illustration of the light shielding plate 4, the linear motor 11, and the linear encoder 12 is omitted.
The laser beam irradiating means 2 includes the trajectory of the droplet 100 ejected from the nozzle hole 92 to be observed after the laser beams 233 and 234 transmitted through the condenser lens 27 intersect each other at the intersection (condensing point) C. Further, laser beams 233 and 234 are irradiated so as to cross each other. In addition, the droplet observation unit is configured by the control unit 6 described above in the present embodiment.

Hereinafter, a method for measuring the flight speed of the droplet 100 using the droplet observation device 5 will be described. In the following description, a case will be described in which the central row of the three nozzle holes 92 of the droplet discharge head 9 is measured.
First, the control means 6 operates the condensing point position detection device 3 to detect the position of the intersection C of the laser beams 233 and 234 and stores the position data in the storage unit 62. When the detection of the position of the intersection C is completed, the light shielding plate 4 is removed.

Next, the control means 6 determines the distance L ₁ between the intersection C and the trajectory of the droplet 100 based on the detected position data of the intersection C and the position data of the nozzle hole 92 stored in advance in the storage unit 62. Ask. Further, the control means 6, the distance _{L 1} obtained, on the basis of the inclination angle data with respect to the optical axis Ax of the laser beam 233, 234 which is previously stored in the storage unit 62, the laser beam 233, 234 and the droplet 100 It calculates the distance L ₂ between the two intersections of the trajectory. Note that the inclination angle of the laser beams 233 and 234 with respect to the optical axis Ax is determined by the characteristics (focal length) of the condenser lens 27.

The droplet 100 discharged from the nozzle hole 92 blocks the laser beams 234 and 233 in this order. At the moment when the droplet 100 blocks the laser beam 234, the output signal of the light receiving element 72 changes, and at the moment when the droplet 100 blocks the laser beam 233, the output signal of the light receiving element 71 changes. Distance the droplet 100 flies during the time difference from the moment when the output signal of the light receiving element 72 is changed until the moment the output signal of the light receiving element 71 is changed is L _2. Therefore, the control means 6, the distance L ₂ is divided by the time difference, it is possible to calculate the flying speed of the droplet 100.

Similarly, the droplet observation device 5 calculates the flight speed of the droplet 100 for the nozzle holes 92 in the left column in FIG. 8 by calculating the distances L ₃ and L ₄ in FIG. 8 from the position of the intersection C. By calculating the distances L ₅ and L ₆ in FIG. 8, the flight speed of the droplet 100 can be measured for the nozzle holes 92 in the right column in FIG.
Further, the droplet observation device 5 operates the moving mechanism to move the droplet discharge head 9 in a direction perpendicular to the paper surface of FIG. Similarly, the flight speed of the droplet 100 can be measured.

According to such a droplet observation device 5, the position of the intersection C can be accurately and easily detected by the condensing point position detection device 3, so that the flying droplet 100 can be accurately and easily observed. it can. Also, when changing the nozzle hole row to be observed, it can be easily handled as described above.
The droplet observation device 5 of the present embodiment measures the flight speed of the droplet 100. However, the present invention is not limited to this, and for example, the volume of the droplet 100, ejection failure, flight curvature, and the like. Other information may be observed.

  As mentioned above, although the condensing point position detecting method, the condensing point position detecting device, the droplet observing method, the droplet observing device, and the droplet discharging device of the present invention have been described with respect to the illustrated embodiments, the present invention is not limited thereto. Is not to be done. Each part which comprises the condensing point position detection apparatus of this invention, a droplet observation apparatus, and a droplet discharge apparatus can be substituted with the thing of the arbitrary structures which can exhibit the same function. Moreover, arbitrary components may be added.

The side view which shows embodiment of the condensing point position detection apparatus of this invention. The side view which shows a laser beam irradiation means. The AA sectional view taken on the line in FIG. 2, the BB sectional view, and the CC sectional view. The side view which shows the state by which the condensing point position was detected in the condensing point position detection apparatus shown in FIG. The front view which shows the light-shielding plate in the condensing point position detection apparatus shown in FIG. The front view which shows the light-shielding plate in the condensing point position detection apparatus shown in FIG. The functional block diagram of the condensing point position detection apparatus (droplet discharge apparatus) of this invention. The side view which shows embodiment of the droplet observation apparatus and droplet discharge apparatus of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Droplet discharge device 2 ... Laser beam irradiation means 21 ... Laser beam irradiation part 23, 231, 232, 233, 234 ... Laser beam 25 ... Beam splitter 26 ... Laser blade 27 ... Condensing lens 3 …… Condensing point position detection device 4 …… Light shielding plate 41 …… Pin hole 5 …… Droplet observation device 6 …… Control means 61 …… CPU 62 …… Storage unit 71, 72 …… Light receiving element 9 …… Droplet discharge head 91 ... Nozzle surface 92 ... Nozzle hole 93 ... Pressure chamber 11 ... Linear motor 12 ... Linear encoder 13 ... Head drive unit 100 ... Droplet Ax ... Optical axis C ... Condensation Point (intersection)

Claims (7)

A condensing point position detecting method for detecting a condensing point position of laser light transmitted through a condensing lens,
A light shielding plate having a pinhole or a slit on the optical axis of the condenser lens is moved along the optical axis direction of the condenser lens, and is disposed on the optical path of the laser light and at the tip of the light shielding plate. A condensing point position detecting method, comprising: detecting an output signal of a light receiving means; and detecting the condensing point position based on the output signal and the position of the light shielding plate. A condensing point position detecting device for detecting a condensing point position of laser light transmitted through a condensing lens,
A light shielding plate having a pinhole or slit on the optical axis of the condenser lens;
Moving means for moving the light shielding plate along the optical axis direction of the condenser lens;
Position detecting means for detecting the position of the light shielding plate in the optical axis direction;
A light receiving means arranged on the tip of the light shielding plate on the optical path of the laser light and photoelectrically converting the received light;
The light condensing is performed based on the output signal of the light receiving means and the position information of the light shielding plate detected by the position detecting means in a state where the moving means is operated to move the light shielding plate in the optical axis direction. A condensing point position detecting device comprising condensing point position detecting means for detecting a point position.   The condensing point position detecting unit according to claim 2, wherein the condensing point position detecting unit determines the position of the light shielding plate when the amount of light received by the light receiving unit is maximized as the condensing point position. The ballistic trajectory of the liquid droplet ejected from the nozzle hole of the liquid droplet ejection head is irradiated with at least one laser beam that has passed through a condenser lens so as to intersect the trajectory, and the laser beam is received. A droplet observation method for observing a flying droplet based on an output signal of the means,
A droplet observing method characterized in that information on a flying droplet is obtained in consideration of information on a condensing point position of the laser beam detected by using the condensing point position detecting method according to claim 1. A droplet observation method for measuring a flight speed of a droplet ejected from a nozzle hole of a droplet ejection head,
The two laser beams transmitted through the condenser lens intersect with each other on the optical axis of the condenser lens, and then irradiate the two laser lights so as to intersect with the droplet trajectory, respectively. The laser beam of the book is received by the light receiving means,
Obtaining the distance between the intersection and the trajectory based on the intersection position of the two laser beams detected using the condensing point position detection method according to claim 1;
Based on the distance, calculate the distance between two intersections of the two laser beams and the ballistic path,
Obtaining information on the flight speed of the droplet based on the distance between the intersections and the time difference of the output signal change of the light receiving means when the droplet intercepts the two laser beams in order. Droplet observation method. A droplet observation apparatus for observing a droplet ejected from a nozzle hole of a droplet ejection head and flying,
Laser light irradiation means for irradiating at least one laser light transmitted through the condenser lens so as to intersect the trajectory of the droplet;
The condensing point position detection device according to claim 2 or 3, wherein the condensing point position of the laser beam is detected.
A light receiving means for receiving the laser beam and performing photoelectric conversion;
Droplet observation means for obtaining information on flying droplets based on the output signal of the light receiving means,
The droplet observation means obtains information on a flying droplet by taking into account information on the condensing point position of the laser beam detected using the condensing point position detecting device. Observation device. A liquid droplet ejection head for ejecting liquid droplets toward the workpiece;
A droplet discharge device comprising: the droplet observation device according to claim 6, which observes a droplet discharged from a nozzle hole of the droplet discharge head and flying.

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