JP2005066454A - Droplet observation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a droplet observation device which efficiently and precisely observes droplets which are discharged and flown from the nozzles of a droplet discharging head. <P>SOLUTION: The droplet observation device 1 observes the droplets 200 which are discharged and flown from the nozzles 101 of the droplet discharging head 100. The device 1 moves the droplet discharging head 100 pitch by pitch by a very small distance by operating a moving means 6 so that the trajectories of the droplets 200 may cross laser beams 233 and 234 under the condition that the laser beams 233 and 234 are irradiated, discharges the droplets 200 at that spot from nozzles 101, detects the relative positions of the droplet discharging head 100 to the optical axes of the laser beams 233 and 234 by detecting the output signals of the light receiving means 4, the relative positions bringing out a maximum change in an output signal of a light receiving means 4, and discharges the droplets 200 from the nozzles 101 in the state in which the position of the droplet discharging head 100 is aligned with the relative positions, and then observes the droplets 200 thus discharged with a droplet observation means 63. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a droplet observation apparatus that can observe a droplet ejected from a nozzle hole of a droplet ejection head and flying.

In recent years, liquid crystal display devices, alignment film devices, overcoat devices, organic EL (Electro-Luminescence) devices, electron emission devices, PDP (Plasma Display Panel) devices, electrophoretic display devices, resist devices using droplet discharge devices It has been proposed to produce microlens arrays, metal wiring, products in the bio field, and the like.
In such a droplet discharge device, since it is necessary to land each droplet at an accurate position on the workpiece, when controlling the droplet discharge device, or when developing or designing the droplet discharge device, etc. In this case, it is necessary to observe the flight state (for example, flight speed, flight direction, landing position, etc.) of the droplet ejected from the nozzle hole of the droplet ejection head.

Conventionally, when observing the flight state of a flying droplet, a laser beam is irradiated to the droplet by an imaging optical device having a laser beam irradiation unit (semiconductor laser) and a light receiving element (photodiode), and the irradiated laser An output signal of a light receiving element that receives light is detected to observe a flight state (for example, see Patent Document 1).
By the way, in order to observe the flight state of the droplet, it is necessary to align the position of the nozzle hole from which the droplet to be observed is ejected with the laser beam irradiation unit and the light receiving element. In particular, it is necessary to align the laser beam in the nozzle hole so that the droplet accurately passes through the center of the laser beam. If this alignment is not performed, accurate measurement cannot be performed. However, a large number of nozzle holes (for example, 180) are formed in the droplet discharge head, and each time the position of the droplets discharged from different nozzle holes is observed, this alignment is set to a different nozzle. There is a problem that it is necessary to carry out every hole.
In addition, since this positioning is performed manually, there is a problem that it takes time and variation in positional accuracy occurs.
JP 2002-48810 A

  An object of the present invention is to provide a droplet observation device capable of efficiently and accurately observing a droplet ejected from a nozzle hole of a droplet ejection head and flying.

Such an object is achieved by the present invention described below.
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 in a direction crossing the flight direction of the droplets;
A light receiving means for receiving the laser beam and performing photoelectric conversion;
Based on the output signal of the light receiving means, a droplet observing means for obtaining information about a droplet ejected from a nozzle hole to be observed;
Moving means for moving the droplet discharge head relative to the laser beam irradiation unit so that the trajectory of the droplet traverses the laser beam;
Control means for controlling the operation of the moving means and the discharge of droplets from the nozzle holes of the droplet discharge head,
The control means operates the moving means in a state where the laser light is irradiated, and pitches the droplet discharge heads by a minute distance so that the trajectory of the droplet traverses the laser light. With respect to the optical axis of the laser beam of the droplet discharge head, the change in the output signal of the light receiving means is maximized by discharging a droplet from the nozzle hole and detecting the output signal of the light receiving means. A relative position is detected, control is performed so that a droplet is ejected from the nozzle hole in a state where the droplet ejection head is positioned at that position, and the ejected droplet is observed by the droplet observation means. And
As a result, the droplets ejected from the nozzle holes of the droplet ejection head and flying can be observed efficiently and accurately.

In the droplet observation apparatus of the present invention, the droplet discharge head has a plurality of nozzle holes,
The moving means can move the droplet discharge head relative to the laser light irradiation means along the arrangement direction of the plurality of nozzle holes,
The control means activates the moving means for each of the plurality of nozzle holes in a state of irradiating the laser light, and moves the droplet discharge head at a minute distance so that the trajectory of the droplet crosses the laser light. The droplet discharge head is configured so that the change in the output signal of the light receiving means is maximized by detecting the output signal of the light receiving means by discharging the liquid droplets from the nozzle holes at each position. The relative position of the laser beam with respect to the optical axis is detected, and control is performed so that the liquid droplet is ejected from the nozzle hole in a state where the liquid droplet ejection head is positioned at that position. It is preferable to observe by observation means.
Thereby, it is possible to efficiently and accurately observe the droplets ejected from the plurality of nozzle holes of the droplet ejection head and flying.

In the droplet observation apparatus of the present invention, it is preferable that the laser beam irradiation unit irradiates a plurality of laser beams that can intersect simultaneously with the trajectory of the droplet.
As a result, the same droplet blocks the laser beam at a plurality of locations, and this blockage causes a temporal change in the amount of laser beam received by the light receiving means. Due to this temporal change, it is possible to measure the time difference between the output signals output from the light receiving means.

In the droplet observation apparatus of the present invention, it is preferable that the droplet observation unit obtains information related to the flight speed of the droplet based on a time difference in output signal change of the light receiving unit with respect to the plurality of laser beams. .
Thereby, the flight speed of the droplet can be observed more accurately.
In the droplet observation apparatus of the present invention, it is preferable that the plurality of laser beams intersect each other.
Thereby, the flight speed of the droplet can be observed more accurately.
In the droplet observation apparatus of the present invention, it is preferable that a position where the plurality of laser beams intersect with each other and a position where the plurality of laser beams intersect with the trajectory of the droplet are different.
Thereby, the information regarding a droplet can be obtained more correctly.

Hereinafter, the droplet observation apparatus of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
FIG. 1 is a plan view showing an embodiment of the droplet observation apparatus of the present invention, FIGS. 2 and 3 are side views showing the embodiment of the droplet observation apparatus of the present invention, and FIG. 4 is A in FIG. -A line sectional view, BB line sectional view and CC line sectional view, FIG. 5 is a block diagram schematically showing the main part of the droplet observation apparatus of the present invention, FIG. 6 and FIG. FIG. 8 and FIG. 9 are graphs schematically showing changes over time in the output signal of the light receiving means, in an enlarged view of a region [S] surrounded by a one-dot chain line in FIG. In the following description, for convenience of explanation, unless otherwise specified, the upper part in FIGS. 2, 3 and 4 is described as “upper” and the lower part is described as “lower”. Further, the laser beam in FIG. 3 is exaggerated for convenience.

  As shown in FIGS. 1 and 2, the droplet observation apparatus 1 observes droplets 200 that are ejected from a plurality of (six in FIG. 1) nozzle holes 101 included in the droplet ejection head 100 and fly. Device. The droplet observation apparatus 1 includes a laser beam irradiating unit 2 that irradiates two laser beams 233 and 234, a light receiving unit 4 that receives the laser beams 233 and 234 and performs photoelectric conversion, and an output signal of the light receiving unit 4. Based on this, a droplet observation unit 63 for obtaining information on the droplet 200, a moving unit 3 for moving the droplet discharge head 100, and a control unit 6 for controlling the operation of the moving unit 3 are provided.

  As shown in FIG. 2, nozzle holes 101 are formed in the nozzle surface (nozzle plate) 102 of the droplet discharge head 100. The nozzle hole 101 is provided with a pressure chamber communicating with the nozzle hole 101 and an actuator (none of which is shown) for changing the pressure of the liquid filled in the pressure chamber. The droplet discharge head 100 discharges the liquid in the pressure chamber as the droplet 200 from the nozzle hole 101 by driving the actuator. The actuator provided in the droplet discharge head 100 is not particularly limited, and may be configured by a piezoelectric actuator or a heating element that generates bubbles by heating a liquid.

The droplet discharge head 100 is driven by a head driving unit (head driver) 300. The head driving unit 300 generates an ejection signal at a predetermined timing (driving frequency). In the droplet discharge head 100, the actuator is operated by the discharge signal input from the head driving unit 300, and the droplet 200 is discharged.
The liquid (including the dispersion liquid) discharged by the droplet discharge head 100 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 device, a migrating material for forming an electrophoretic material 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 And a light diffusing material for forming a light diffuser.
Such a droplet discharge head 100 is installed so as to be movable along the arrangement direction of the six nozzle holes 101 (hereinafter simply referred to as “the arrangement direction”) by the guide rail 31 of the moving means 3. .

  As shown in FIG. 5, the control unit 6 controls the laser beam irradiation unit 2, the moving unit 3, the light receiving unit 4, and the head driving unit 300. The control unit 6 includes a CPU (Central Processing Unit) 61, a storage unit 62, and a droplet observation unit 63. The storage means 62 has a storage medium (recording medium) that can be read by the CPU 61, and this storage medium is composed of a magnetic or optical recording medium, a semiconductor memory, or the like.

As shown in FIGS. 1 to 3, 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 lens 27.
The laser beam 23 irradiated by the operation of the laser beam irradiation means 2 is received by the light receiving means 4 while its cross section changes as shown below. FIG. 3 is a side view of a part of the droplet observation apparatus 1 (in the vicinity of the laser beam irradiation means 2) in FIG.

First, as shown in FIG. 4, the laser light 23 emitted from the laser light irradiation unit 21 has a substantially circular cross section (see FIG. 4A).
Next, when the laser beam 23 passes through the beam splitter 25, the laser beam 23 branches into a laser beam 231 and a laser beam 232. The cross sections of the laser beams 231 and 232 are almost semicircular (see FIG. 4B).

Next, when the laser beams 231 and 232 pass through the laser blade 26, the upper portion of the laser beam 231 is shielded and the lower portion of the laser beam 232 is shielded. At this time, the laser beams 231 and 232 are laser beams 233 and 234, which are band-shaped light beams, respectively, and the cross sections thereof are elongated (see FIG. 4C).
Next, the laser beams 233 and 234 are collected by the lens 27, intersect each other, and travel in a direction intersecting the flight direction of the droplet 200 (see FIGS. 1 and 2).

Next, the laser beams 233 and 234 intersect simultaneously with the trajectory of the droplet 200 and are received by the light receiving means 4 (see FIGS. 1 and 2).
With such a configuration, the same droplet 200 shields the laser beams 233 and 234, respectively, and this light shielding causes a temporal change in the amount of received light with the laser beams 233 and 234 received by the light receiving means 4. Due to this temporal change, the time difference between the output signals output from the light receiving means 4 can be measured.

As shown in FIGS. 1 and 2, the light receiving means 4 is composed of light receiving elements 433 and 434 provided vertically at a constant distance H (distance indicated by H in FIG. 2).
The light receiving elements 433 and 434 are installed on the opposite side of the lens 27 of the laser light irradiation means 2 through the flight region 400 of the droplet 200. That is, the laser beams 233 and 234 are emitted from the side opposite to the light receiving elements 433 and 434 through the flight region 400.

As shown in FIG. 1, the moving means 3 extends in the arrangement direction and is installed in the same direction as the guide rail 31 and the guide rail 31 that guides the droplet discharging head 100 in the same direction. And a servo motor 34 for applying a rotational force to the ball screw 33.
The moving unit 3 moves the droplet discharge head 100 relative to the laser beam irradiation unit 2 so that the trajectory of the droplet 200 discharged from the nozzle hole 101 to be observed crosses the laser beams 233 and 234.

  The control means 6 controls the laser light irradiation means 2, the moving means 3, the light receiving means 4 and the head driving unit 300 as shown below, and observes the droplet 200 by the droplet observation means 63 (FIG. 1, FIG. 2). Note that the droplet discharge head 100 moves in the direction of the arrow in FIG. 1 by the operation of the moving unit 3, but in the following, simply “the droplet discharge head 100 moves” or “the droplet discharge head 100 moves. "

  First, the control means 6 moves the droplet discharge head 100 to a predetermined reference position (initial position) in a state where the laser beams 233 and 234 are irradiated. The initial position is not particularly limited. For example, the initial position is preferably a position where the nozzle hole 101a and the laser beams 233 and 234 do not overlap in a plan view. Examples of such an initial position include a position where the edge 103 on the nozzle hole 101a side of the nozzle surface 102 and the laser beams 233 and 234 overlap with each other in plan view. Hereinafter, this position will be described as an initial position.

Next, the control unit 6 inputs a discharge start command for causing the head driving unit 300 to discharge the droplet 200. Based on this discharge start command, the head drive unit 300 generates a discharge signal at a predetermined drive frequency, and the droplet 200 is discharged from the nozzle hole 101 of the droplet discharge head 100. The drive frequency is not particularly limited, but can be about 100 Hz, for example.
Along with this ejection, the control means 6 pitches (moves) the droplet ejection head 100 from the initial position by a minute distance so that the trajectory of the droplet 200a ejected from the nozzle hole 101a crosses the laser beams 233 and 234. ). The feed amount (distance) for pitch feeding is not particularly limited, but is preferably sufficiently smaller than the distance between the centers of adjacent nozzle holes 101 and sufficiently smaller than the diameter of the droplet 200. Such a feed amount can be, for example, about 1 μm. Further, the moving time during which the droplet discharge head 100 moves through this distance is not particularly limited, but can be, for example, about 5 ms. In addition, it is preferable to set so that the droplet 200 (200a) is not discharged within this movement time.

Next, the position of the droplet discharge head 100 where the droplet 200a passes through the centers of the laser beams 233 and 234 (the position of the nozzle hole 101a with respect to the optical axis of the laser beams 233 and 234) is detected. The detection of this position will be described in detail later.
Next, with the droplet discharge head 100 positioned at this position, the discharged droplet 200a is observed by the droplet observation means 63.
Thereafter, this is repeated for the droplets 200c, 200d, 200e, and 200f corresponding to the nozzle holes 101c, 101d, 101e, and 101f, respectively.

  Next, detection of the position of the droplet discharge head 100 (nozzle hole 101) such that each droplet 200 discharged from the plurality of nozzle holes 101 passes through the centers of the laser beams 233 and 234 will be described. . In this description, the nozzle hole 101b is representatively described as the nozzle hole 101 to be detected. In this detection, among the two light receiving elements 433 and 434, the light receiving element 434 is used, and the two laser beams 233 and 234 use the laser light 234 corresponding to the light receiving element 434.

  First, as shown in FIG. 6A, when the droplet discharge head 100 is pitch-fed (n−2) times and the feeding is stopped, the droplet 200b does not intersect with the laser beam 234, and laser It passes (flights) near the light 234. Before and after this passage, the output signal of the light receiving element 434 is A / D converted by an A / D converter (not shown) at a timing based on a clock signal generated from a clock signal generating means (not shown). At the same timing, it is once latched (held) by a latch circuit (not shown). Each time the output signal is latched, the latched output signal is stored in the storage medium (storage means 62). The output signal at this position does not change as shown in FIG.

Next, as shown in FIG. 6B, when the droplet discharge head 100 is fed by one pitch ((n-1) times) and the feeding is stopped, a part of the droplet 200b is a laser. The light 234 passes while being blocked. The output signal at this position changes as shown in FIG. At this time, by the operation of the control means 6, the output signals stored at the time of each latch are compared at any time, the difference is obtained from the maximum value and the minimum value, and the change amount U _n-1 of the output signal is stored in the storage medium. .

Then, similarly, stores the change amount U _n of the output signal of the position where the droplet discharge head 100 and sends n times the pitch in the storage medium (see FIG. 7 (C), the FIG. 9 (C)).
Then, taking the difference between the change amount _{U n-1} and the change amount _{U n,} and stores the value of the difference _{(U n-1} -U _n) is positive or negative.
Next, similarly, the change amount U _{n + 1} of the output signal at the position where the droplet discharge head 100 is pitch-fed (n + 1) times is stored in the storage medium (see FIGS. 7D and 9D).

Then, taking the difference between the change amount _{U n} and the change amount _{U n + 1,} and stores the value of the difference _{(U n -U} n _{+ 1)} is positive or negative.
Next, it is determined by the operation of the control means 6 that such a difference turns from negative to positive, and the position determined by this determination is the droplet discharge head 100 through which the droplet 200 passes through the centers of the laser beams 233 and 234. The position of Note that the pitch number from the initial position at this position is preferably stored in a storage medium.

For example, when the value of the difference (U _n−1 −U _n ) is negative and the value of the difference (U _n −U _{n + 1} ) is positive, the position where the droplet discharge head 100 is fed n times pitches is the laser beam 233. 234 is the position of the droplet discharge head 100 where the droplet 200b passes through the center (the position of the nozzle hole 101b with respect to the optical axis of the laser beams 233 and 234).
Note that n is an integer. In the present embodiment, (n−2) is also an integer, and therefore n is preferably an integer of 2 or more.

In FIGS. 6 and 7, the widths of the laser beams 233 and 234 are drawn larger than those of the droplet 200. On the other hand, even when the widths of the laser beams 233 and 234 are smaller than the droplet 200, the tendency of the change in the intensity of the output signal from the light receiving elements 433 and 434 does not change. The position of the ejection head 100 can be detected.
Further, the light receiving element used for such detection is not limited to the light receiving element 434 as described above, and may be the light receiving element 433. Similarly, the laser beam is not limited to the laser beam 234 but may be the laser beam 233 corresponding to the light receiving element 433.

The processing of the output signal from the light receiving means 4 (light receiving element 434) by such a method is only an example. Therefore, in order to achieve the detection of the position of the droplet discharge head 100 so that the change in the output signal of the light receiving means 4 is maximized, the method is not limited to this method.
With such a configuration, the droplet observation apparatus 1 changes the position of the droplet discharge head 100 based on the control of the control unit 6, thereby discharging the discharged droplet 200 in each of the six nozzle holes 101. It can be observed.
As a result, the droplet 200 ejected from the six nozzle holes 101 of the droplet ejection head 100 and flying can be observed efficiently and accurately.

As described above, the droplet observation means 63 is based on the time difference of the output signal change of the light receiving means 4 that receives the two laser beams 233 and 234, and the droplet 200 ejected from the nozzle hole 101 to be observed. It is configured to obtain information on the flight speed of the aircraft.
As a result, the distance h (distance indicated by h in FIG. 2) that the droplet 200 moves (flies) between the laser beam 233 and the laser beam 234, which has been measured in advance, is measured by the droplet observation means 63. The flying speed of the droplet 200 can be calculated by dividing by the time difference between the output signal changes of the received light receiving elements 433 and 434. The flight speed calculated in this way has less errors and is a more accurate numerical value.

In order to calculate the flying speed of the droplet 200, it is necessary to detect the droplet 200 with the light receiving element 433 and the light receiving element 434. Therefore, the laser beam 233 and the laser beam 234 intersect with each other (FIG. 2). And the positions where the laser beams 233 and 234 intersect with the trajectory of the droplet 200 are different.
Thereby, since the time difference can be measured, the flight speed of the droplet 200 can be calculated.

  When observing such a droplet 200, the observed droplet 200 is preferably in the vicinity of a point F where the laser beam 233 and the laser beam 234 intersect. At this time, the distance h becomes very small. On the other hand, since the light receiving elements 433 and 434 themselves have a certain size, it is difficult to set the distance H as small as the distance h. However, the distance H can be set large because the laser beam 233 and the laser beam 234 intersect each other as in this embodiment.

The plurality of nozzle holes 101 is not limited to all the nozzle holes 101 provided in the droplet discharge head 100, and may be any nozzle hole 101 that discharges the droplet 200 to be observed.
Further, the number of nozzle holes 101 formed in the droplet discharge head 100 is not limited to six as in this embodiment, and may be two to five or seven or more.

Further, the flight state of the droplet 200 that can be observed is not limited to the flight speed as in the present embodiment, and examples thereof include ejection failure, flight bend, and flight direction.
Further, the moving means 3 is not limited to the one using the ball screw 33 as in this embodiment, and may use any structure, for example, a belt such as a timing belt, a rack and pinion gear, a linear An arbitrary configuration using a motor or the like can be used. Further, a linear scale may be installed so as to further improve the positional accuracy of the droplet discharge head 100.

In addition, the moving unit 3 is not limited to moving the droplet discharge head 100 with respect to the laser beam irradiation unit 2 (laser beams 233 and 234) as in the present embodiment. The laser light irradiation means 2 and the light receiving means 4 may be moved.
Further, the number of laser beams 233 and 234 that intersect the trajectory of the droplet 200 is not limited to two as in this embodiment, and may be one or three or more laser beams.

Further, the light receiving means 4 is not limited to being configured by a plurality (two) of light receiving elements 433 and 434 as in the present embodiment, and may be configured by using a CCD camera, for example.
The light receiving elements 433 and 434 are not particularly limited, and examples thereof include a photodiode and a photomultiplier tube.
The embodiment of the droplet observation apparatus of the present invention has been described above, but the present invention is not limited to this. Each unit constituting the droplet observation apparatus can be replaced with any component that can exhibit the same function. Moreover, arbitrary components may be added.

It is a top view which shows embodiment of the droplet observation apparatus of this invention. It is a side view which shows embodiment of the droplet observation apparatus of this invention. It is a side view which shows embodiment of the droplet observation apparatus of this invention. It is the sectional view on the AA line in FIG. 3, BB sectional drawing, and CC sectional drawing. It is a block diagram which shows roughly the principal part of the droplet observation apparatus of this invention. FIG. 2 is an enlarged view of a region [S] surrounded by an alternate long and short dash line in FIG. 1. FIG. 2 is an enlarged view of a region [S] surrounded by an alternate long and short dash line in FIG. 1. It is a graph which shows typically the time-dependent change of the output signal of a light-receiving means. It is a graph which shows typically the time-dependent change of the output signal of a light-receiving means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Droplet observation apparatus 2 ... Laser beam irradiation means 21 ... Laser beam irradiation part 23,231,232,233,234 ... Laser beam 25 ... Beam splitter 26 ... Laser blade 27 ... Lens 3 ... ... Moving means 31 ... Guide rail 33 ... Ball screw 34 ... Servo motor 4 ... Light receiving means 433, 434 ... Light receiving element 6 ... Control means 61 ... CPU 62 ... Storage means 63 ... Droplet observation means 100 …… Droplet ejection head 101, 101a, 101b, 101c, 101d, 101e, 101f …… Nozzle hole 102 …… Nozzle surface 103 …… Edge 200, 200a, 200b, 200c, 200d, 200e, 200f …… Liquid Drop 300 …… Head drive unit 400 …… Flight area

Claims (6)

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 in a direction crossing the flight direction of the droplets;
A light receiving means for receiving the laser beam and performing photoelectric conversion;
Based on the output signal of the light receiving means, a droplet observing means for obtaining information about a droplet ejected from a nozzle hole to be observed;
Moving means for moving the droplet discharge head relative to the laser beam irradiation unit so that the trajectory of the droplet traverses the laser beam;
Control means for controlling the operation of the moving means and the discharge of droplets from the nozzle holes of the droplet discharge head,
The control means operates the moving means in a state where the laser light is irradiated, and pitches the droplet discharge heads by a minute distance so that the trajectory of the droplet traverses the laser light. With respect to the optical axis of the laser beam of the droplet discharge head, the change in the output signal of the light receiving means is maximized by discharging a droplet from the nozzle hole and detecting the output signal of the light receiving means. A relative position is detected, control is performed so that a droplet is ejected from the nozzle hole in a state where the droplet ejection head is positioned at that position, and the ejected droplet is observed by the droplet observation means. Droplet observation device. The droplet discharge head has a plurality of nozzle holes,
The moving means can move the droplet discharge head relative to the laser light irradiation means along the arrangement direction of the plurality of nozzle holes,
The control means operates the moving means for each of the plurality of nozzle holes in a state of irradiating the laser light, and moves the droplet discharge head at a minute distance so that the trajectory of the droplet crosses the laser light. The droplet discharge head is configured such that a change in the output signal of the light receiving means is maximized by detecting the output signal of the light receiving means by discharging a droplet from the nozzle hole at each position and detecting the output signal of the light receiving means. The relative position of the laser beam with respect to the optical axis is detected, and control is performed so that the droplet is ejected from the nozzle hole in a state where the droplet ejection head is aligned at that position. The droplet observation apparatus according to claim 1, which is observed by an observation means.   The droplet observation apparatus according to claim 1, wherein the laser beam irradiation unit irradiates a plurality of laser beams that can intersect simultaneously with the trajectory of the droplet.   The droplet observation apparatus according to claim 3, wherein the droplet observation unit obtains information on a flight speed of the droplet based on a time difference in output signal change of the light receiving unit with respect to the plurality of laser beams.   The droplet observation apparatus according to claim 3 or 4, wherein the plurality of laser beams intersect each other.   The droplet observation apparatus according to claim 5, wherein a position where the plurality of laser beams intersect with each other is different from a position where the plurality of laser beams intersect with the trajectory of the droplet.

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