JP2013193404A - Droplet observation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To observe a droplet discharged from a nozzle and laded on a landed member and a droplet landed on the landed member even when a gap between a nozzle plate of a head and the landed member becomes small.SOLUTION: A droplet discharged from a nozzle is irradiated with light transmitted through a translucent landed member 12 and reflected by a nozzle surface of a nozzle plate 13. The light reflected by the droplet is reflected by the nozzle surface of the nozzle plate 13 again, and transmitted through the landed member 12 to be guided to an imaging element 24. A landed droplet 30 is observed through an optical image formed by the imaging element 24.

Description

  The present invention relates to a droplet observation apparatus for observing and evaluating droplets ejected from nozzles formed on a droplet ejection head.

  This type of droplet discharge head is used as a recording head of an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a plotter. The image forming apparatus here forms an image on a recording material, but the material of the recording material is not limited to paper, and is a thread, fiber, fabric, leather, metal, plastic, glass, It means an apparatus for forming an image by discharging a liquid onto any recording material such as wood or ceramics. Image formation not only applies an image having a meaning such as a character or a figure to a recording material, but also applies an image having no meaning such as a pattern to the recording material (simply ejects a droplet). ) Also means. The liquid ejected as droplets is not limited to so-called ink, and is not particularly limited as long as it becomes liquid when ejected, and includes, for example, DNA samples, resists, pattern materials, and the like. It is.

  In an ink jet recording apparatus typified by such a droplet discharge apparatus, in order to form a good coating pattern, a head including a nozzle for discharging ink, an ink discharged from the nozzle, and a recording medium on which the ink lands It is necessary to ensure consistency with each other. For this purpose, in addition to the individual characteristics of the head, ink, and recording medium, it is necessary to grasp the characteristics of the entire recording process when these are combined. For this reason, various droplet observation apparatuses have been proposed. For example, what is described in Patent Document 1 is known. The droplet observation apparatus disclosed in Patent Document 1 is configured to receive a droplet discharged from a nozzle and landing on a workpiece corresponding to a landing member or a droplet landed on the workpiece from an oblique direction not blocked by the nozzle plate of the head. An optical image is created and observed using an imaging means such as a high-speed camera.

  However, the droplet observation apparatus of Patent Document 1 is limited to a case where a sufficient gap can be secured between the nozzle plate of the head and the workpiece. When the gap between the nozzle plate of the head and the workpiece becomes small, the landing droplet that has landed on the workpiece is blocked by the nozzle plate, and the landing droplet cannot be imaged by the imaging means and cannot be observed. As a means different from the droplet observation apparatus of Patent Document 1, a translucent member is used as the landing member, and the flying droplet is observed through the back surface of the translucent landing member. A way to do this is conceivable. In this method, even when the gap between the nozzle plate and the member becomes small, it is possible to observe the landed droplet on the front surface of the translucent landing member. However, in the evaluation of landed droplets, there are cases where it is desired to know the cause of the generation of minute droplets called satellites that adhere around the main main droplet. For such an evaluation purpose, in the method of observing the droplet flying from the back surface opposite to the landing side of the translucent landing member, the droplet discharged from the nozzle is opposed to the discharge direction. Since it is observing from the direction which does, it is difficult to evaluate the said evaluation objective. Specifically, when trying to observe a microdroplet adhering to a translucent landing member through a translucent landing member, the attached microdroplet separates from the main droplet during flight. It is difficult to discriminate whether it is a micro droplet that has been separated or a micro droplet that has been separated from the main droplet by the reaction upon landing. In general, the shape of the landed droplet is three-dimensional and not flat. For this reason, it is difficult to observe the three-dimensional shape of the landed droplet on the front side even when looking at the back side of the landed droplet on the translucent member. Is insufficient.

  The present invention has been made in view of the above problems, and its purpose is to provide a liquid that is ejected from the nozzle and landed on the landing member even when the gap between the nozzle plate of the head and the landing member is reduced. It is an object of the present invention to provide a droplet observation device that can observe a droplet and sufficiently observe a droplet that has landed on a landing member.

  In order to achieve the above object, a first aspect of the present invention provides a droplet observation apparatus for observing a droplet discharged from a nozzle and landing on a landing member and a droplet that has landed on the landing member. A nozzle plate that is formed of a member and has the nozzle formed on the opposite side of the nozzle with the landing member interposed between the droplets that land on the landing member and the light reflected and scattered by the landed droplets An observation optical means configured to obtain an optical image by being reflected on the surface is provided.

  In the present invention, the droplets that land on the translucent landing member and the landed droplets are illuminated, and light reflected and scattered from these droplets is generated. The reflected and diffused light is reflected by the nozzle plate, passes through the translucent landing member, reaches the observation optical means, and an optical image is obtained by the observation optical means. The liquid droplets ejected from the nozzle and landed on the landing member are irradiated with light reflected by the nozzle plate. For this reason, even if the gap between the nozzle plate of the head and the landing member becomes small, the light reflected from the liquid droplets landing on the landing member reaches the observation optical means and reaches the landing member. An optical image of the drop is obtained. In addition, when observing a droplet that has landed on the landing member, it is not a reflected light from the back side of the landing member, but a droplet that has landed by irradiating the droplet landing from the front side of the landing member. An optical image of a droplet is obtained in which the reflected light is reflected by the nozzle plate through the translucent landing member and landed on the landing member by the observation optical means. For this reason, the specific effect that the three-dimensional shape of the droplet landed on the landing member can be sufficiently observed is obtained.

It is the schematic which shows the structure of the droplet observation apparatus which concerns on embodiment. It is the figure which expanded the part of the landed droplet. It is a top view which shows the mode of irradiation in the nozzle surface of a nozzle plate. It is the schematic which shows the structure of the modification 1 of the droplet observation apparatus which concerns on embodiment. It is the schematic which shows the structure of the modification 2 of the droplet observation apparatus which concerns on embodiment. It is the figure which looked at the structure of the part of an objective lens and a ring illumination unit from the coating substrate side. It is the schematic which shows the structure of the modification 3 of the droplet observation apparatus which concerns on embodiment. It is the schematic which shows the structure of the modification 4 of the droplet observation apparatus which concerns on embodiment. It is a top view which shows a light shielding element. (A) is sectional drawing of a nozzle, (b) is a graph which shows light intensity distribution of the illumination light irradiated to a nozzle vicinity.

  FIG. 1 is a schematic diagram showing a configuration of a droplet observation apparatus according to the present embodiment. The droplet observation apparatus of the present embodiment shown in the figure includes an ink discharge unit 10 and an observation optical unit 20. The ink discharge unit 10 includes an ink discharge head 11 that discharges droplets from a plurality of ink discharge nozzles formed on a nozzle plate 13 and a translucent landing member 12 that causes the discharged droplets to land. doing. The observation optical unit 20 is for observing the landing droplet 30 that has landed on the landing member 12. As will be described later, since the reflected light from the nozzle plate 13 is used for the observation of the landing droplet 30, it is desirable that the front surface of the nozzle plate 13 is a mirror surface, but it is made of a light-absorbing material. Or there may be irregularities that cause light scattering on the front surface. Then, it may be in a state in which a light beam necessary for imaging the landing droplet 30 can be secured, that is, in a state in which an image of the landing droplet 30 is formed on an imaging surface of an image sensor described later. The translucent landing member 12 is made of a single material such as glass or resin, or a substrate on which a coating for suppressing the wetting and spreading of droplets is applied, or a plurality of substrates. Those formed by overlapping can be used. In order to observe the landing droplet 30 through the landing member 12, it is desirable that the landing member 12 is transparent at the wavelength of light used, but it is made of a material that absorbs light somewhat. However, there is no problem if the transmittance necessary for imaging the landing droplet is secured. Further, as long as an image of the landing droplet 30 is formed on the imaging surface of the imaging device 24 of the observation optical unit 20, unevenness that causes some light scattering on the front surface of the landing member 12 or the like. It doesn't matter if there is.

  The distance (gap) between the nozzle plate 13 of the ink discharge head 11 and the landing member 12 is arranged to be the same distance as when the application pattern is actually formed using the ink discharge head 11. . Specifically, it arrange | positions at the distance between 0.1 [micrometers]-3 [mm], for example. On the other hand, the observation optical unit 20 uses a partially reflecting mirror 22 for an illumination optical system for applying light to the landing droplet and an imaging optical system for forming an image of scattered light from the landing droplet on the image sensor. And integrated. In the illumination optical system, first, light from the lamp 25 that is a light source is incident on the incident side of the fiber light guide 27 by the lens 26, and light is emitted from the end surface on the exit side of the fiber light guide 27. For light from the end face on the exit side of the fiber light guide 27, an image of the exit end face of the fiber light guide 27 is formed on the image sensor and overlaps the image of the landing droplet 30 in the imaging optical system described later. In order to prevent this problem, the light beam is adjusted using the pinhole 28 and the lens 29 and is incident on the partial reflection mirror 22. In the partial reflection mirror 22, a part of the amount of light emitted from the fiber light guide path 27 is reflected and incident on the objective lens 21. Then, by the objective lens 21, the position of the focal point indicated by the line shown in FIG. 1 and the inverted position becomes the focal position of the light reflected by the nozzle plate 13. That is, the distance D1 from the reflecting surface of the nozzle plate 13 to the focal position of the imaginary line and the distance D2 from the reflecting surface of the slip plate 13 to the focal position of the light reflected by the nozzle plate 13 are substantially equal.

  Here, the partial reflection mirror 22 is for controlling the ratio of the amount of light for illuminating the landing droplet 30 and the amount of light when the scattered light from the landing droplet 30 is guided to the image sensor 24. The partial reflection mirror 22 may be a glass substrate, a glass substrate having a dielectric film formed thereon, or the like. As the value of the reflectance of the partial reflection mirror 22, for example, a value of about 1 to 10% can be used. The detailed value is determined from the light quantity of the illumination lamp 25, the sensitivity of the image sensor 24, the reflectance of the nozzle plate 13, and the like. The partial reflection mirror 22 reflects the illumination light toward the objective lens 21 by the illumination optical system. In the imaging optical system, the light from the objective lens 21 is transmitted and guided to the imaging lens 23. . At this time, a part of the light amount is reflected here, and the remaining light is incident on the imaging lens 23. The light emitted from the objective lens 21 in the illumination optical system passes through the translucent coating substrate as shown in FIG. 2 and is reflected by the front surface of the nozzle plate 13 of the ink ejection head 11 to form landing droplets. Illuminates from the nozzle plate side.

  On the other hand, in the imaging optical system, as shown in FIG. 2, the light reflected by the surface of the nozzle plate 13 out of the light scattered by the landing droplet 30 is used to remove the landing droplet from the ink ejection head side (nozzle plate side). The optical image seen from the camera is acquired. That is, the objective lens 21 and the imaging lens (not shown) constituting the imaging optical system have an imaging relationship between the landing droplet 30 and the imaging element 24 in the optical path reflected by the nozzle plate 13 as shown in FIG. It is going to be established. In the present embodiment, since the optical axis of the observation optical unit 20 is configured to coincide with the axis connecting the nozzle and the landing droplet 30, the scattered light from the landing droplet 30 is incident on the objective lens 21. The light is reflected by the peripheral region 32 of the nozzle 31 as shown in FIG. There is also reflected light from the ink in the nozzles, but generally, the meniscus shape has a curvature, so the imaging relationship is not established. As described above, the peripheral area 32 in FIG. 3 used as a reflecting surface is preferably a mirror surface. However, for example, about half of the peripheral area in FIG. 3 contributes to image formation due to absorption or scattering due to dirt or unevenness. Even without that, it is possible to obtain an image of the landing droplet 30 in the image sensor 24 of FIG. Further, as can be seen from FIG. 2, a part of the light beam traveling from the landing droplet 30 to the objective lens 21 is blocked by the landing droplet itself, but the droplet spreads wet on the landing member 12, for example, Even if about half of the light rays incident on the objective lens 21 are blocked, an image of the landing droplet 30 can be obtained.

  As the objective lens and the imaging lens used for configuring such an optical system, a lens used in an optical microscope can be used. In addition to the wavelength and magnification of the light used for observation, the lens specifications are determined from the numerical aperture required for the objective lens and the working distance (distance between the focal point of the objective lens and the lens surface). For example, with respect to the working distance, the objective lens 21 is prevented from contacting the translucent landing member 12. Therefore, if the thickness of the translucent landing member 12 in FIG. 2 is d1 and the distance between the nozzle surface and the surface of the landing member 12 is d2, the working distance is larger than d1 × 2 + d2. ing.

  On the other hand, the numerical aperture of the objective lens is set within a range that satisfies a plurality of conditions described below. First, the reflection region of the peripheral region 32 of the nozzle 31 shown in FIG. 3 can be secured, and second, the light rays necessary for image formation are blocked by the liquid droplets that have landed on the translucent coating substrate. There is no such thing. Third, the depth of focus of the imaging optical system may be a value smaller than the distance between the nozzle and the light-transmitting coated substrate (distance d2 in FIG. 2). Fourth, the optical resolution necessary for observing the shape of the landing droplet may be secured.

  Each of the first and second conditions is a necessary condition for obtaining an optical image with the configuration of the present invention. For example, when the distance d1 between the nozzle and the translucent coating substrate in FIG. 2 is 500 [μm] and the nozzle diameter is 20 [μm], in order to secure the peripheral region 32 in FIG. The first condition is satisfied by using an objective lens having a numerical aperture of at least 0.02. In addition to this condition, for example, when the diameter of the landing droplet is 80 [μm], the second condition is not satisfied. In this case, a numerical aperture of 0.08 or more is required. . The third condition is not an indispensable condition for obtaining an optical image, but an objective lens having a small focal distance (distance d2 in FIG. 2) between the nozzle surface and the front surface of the landing member and a large focal depth is used. When used, an image of the nozzle plate or an image of the landing droplet viewed from the objective lens side is observed with the image of the landing droplet, and this may cause trouble in observing only the landing droplet. In order to cope with this situation, in the present invention, the focal depth of the imaging optical system is adjusted so that only the landing droplet can be observed well. For example, in the above example, an objective lens having a numerical aperture of about 0.3 that has a depth of focus sufficiently smaller than the separation distance (distance d2 in FIG. 2) between the nozzle surface and the surface of the landing member is used. Therefore, good observation can be performed. Similarly, the fourth condition is not an essential condition for forming an optical image unless the diameter of the nozzle and the size of the landing droplet are extremely small such as several μm. However, an appropriate resolution is required for a requirement such as measuring the size of a landing droplet, and it is necessary to use an objective lens having a numerical aperture that satisfies this requirement.

  In addition to this, an objective lens for a normal microscope is designed under the condition that the space between the lens and the observation target is filled with air, so that the light-transmitting landing member is transmitted when the numerical aperture is increased. As a result, the aberration caused by the image becomes larger and the image obtained by the image sensor becomes blurred. In such a case, the present invention uses an objective lens that is optically corrected for the optical path length of the landing member (the product of the refractive index of the substrate and the distance through which the light passes). For example, when the translucent landing member is a glass substrate having a thickness of 1 [mm] and the numerical aperture of the objective lens is 0.4, such an objective lens is used.

  As the imaging element, an element capable of acquiring two-dimensional image data such as a CCD camera or a CMOS camera can be used. If a high-speed camera is used, it becomes possible to observe the landing state in more detail. The signal output from the image sensor can be transferred to a computer (not shown) to observe the landing state on the display. It is also possible to measure the size of the landing droplet or save it as electronic data.

Next, an example of a procedure for actually observing the landing droplet using the apparatus configuration as described above will be briefly described.
(1) The separation distance between the nozzle surface of the ink ejection head and the front surface of the landing member is adjusted to a value for a condition to be observed.
(2) The position of the observation optical unit is adjusted so that the nozzle for discharging the droplet is observed.
(3) The observation optical unit (or only the objective lens) is moved in the upward direction on the paper surface of FIG. 2 so that the front surface of the landing member on which the droplet is landed is focused.
(4) A droplet is ejected, and an image of the landing of the droplet is captured and acquired as image data.

  By operating the droplet observation device as described above, the shape of the landing droplet can be observed from the ink discharge head side (nozzle side), and whether the satellite is generated before landing or after landing It is possible to evaluate such as.

  In the present embodiment, the configuration using the fiber light guide for the illumination optical system has been exemplified, but the present invention is not limited to this, and the light guide is configured only by the lamp and the lens without using the fiber light guide. Or the structure which uses LED as a light source can be used. In addition, although an infinite system configuration in which the objective lens and the imaging lens are combined is illustrated, the present invention is not limited to this, and a finite system configuration as in Modification 1 of the embodiment shown in FIG. It does not matter.

  Next, a second modification of the embodiment will be described with reference to FIG. 5, the same reference numerals as those in FIG. 1 denote the same components. As shown in FIG. 5, the droplet observation apparatus according to the second modification of the embodiment includes a ring-shaped ring illumination unit 41 in which an illumination optical system for illuminating a landing droplet is disposed around the objective lens. It has become. This configuration is the same as the configuration for obtaining a dark field image in an optical microscope. FIG. 6 is a view of the configuration of the objective lens and the ring illumination unit from the coated substrate side. As shown in FIG. 5, as the ring illumination unit 41, an illumination unit used in an optical microscope (mainly an actual microscope) can be used. For example, as in the first embodiment, the light from the lamp of the light source is conveyed to the vicinity of the objective lens using a fiber light guide, and is emitted in a ring shape, or the LED is arranged in a plurality of circles. Can be used. The configuration of the imaging optical system other than the illumination optical system is the same as that of the first embodiment. In such a configuration, after the light emitted from the ring illumination unit 41 passes through the translucent landing member 12, the landing droplet 30 is reflected by the nozzle plate 13 and directed toward the landing droplet 30. Illuminated. On the other hand, the scattered light from the landing droplet 30 forms an image on the image sensor 24 in the same manner as in the first embodiment except for the loss due to the partial reflection mirror. In the configuration of the present embodiment, extra light from other than the landing droplets is taken into the imaging element, such as the illumination light being reflected by a translucent landing member before reaching the nozzle plate and reaching the imaging element. Can be suppressed. Particularly, the reflection of the illumination light by the translucent landing member is large, and the configuration of the first embodiment is effective when the image of the landing droplet cannot be obtained with sufficient contrast in the image sensor.

  Next, Modification 3 of the embodiment will be described with reference to FIG. 7, the same reference numerals as those in FIG. 5 denote the same components. In the droplet observation apparatus according to the third modification of the embodiment, the shape of the landing droplet can be more stereoscopically observed as shown in FIG. For this purpose, the optical axis of the objective lens 21 is configured to have an angle from a direction perpendicular to the front surface of the translucent landing member 12. The angle is adjusted according to the direction in which the landing droplet is desired to be observed. However, there are restrictions such as the working distance of the objective lens 21 and the depth of focus of the observation optical unit 20. For this reason, the adjustment is made in a range in which the observation optical unit 20 does not come into contact with the coating substrate, and in a range in which the optical image of the landing droplet 30 can be obtained in the image sensor 24. Since the optical axis of the imaging optical system is inclined, when the optical image of the landing droplet 30 is arranged at the center of the imaging device, the optical axis of the imaging optical system is shifted from the center of the nozzle. It becomes. For example, in FIG. 7, the optical axis (indicated by the alternate long and short dash line) of the image sensor 24 is slightly shifted from the center axis (indicated by the dotted line) of the nozzle to the right side in the drawing.

  Next, a fourth modification of the embodiment will be described with reference to FIG. 8, the same reference numerals as those in FIG. 1 denote the same components. In the droplet observation apparatus according to the fourth modification of the embodiment, as shown in FIG. 8, the central portion of the illumination light beam is shielded to prevent the illumination light for illuminating the landing droplet from hitting the droplet of the nozzle. A ring-shaped light beam is formed. Specifically, the light shielding element 51 is provided on the optical path between the lens 29 and the partial reflection mirror 22. The light shielding element 51 may be any structure as long as it can block light at the central portion of the light beam. For example, a light shielding film 53 is formed by vapor-depositing a material such as chromium on a glass substrate 52 as shown in FIG. The illumination light irradiation region 54 may be present around the light shielding film 53. This solves the problem that the characteristics of the ink change when the light for illuminating the landing droplet hits the ink of the nozzle, and the same original landing state as in the case where illumination accompanying observation is not performed can be observed. It becomes like this.

  In the illumination optical system according to the modified example 4 of the embodiment, the light emitted from the fiber light guide 27 and the light flux adjusted by the pinhole 28 and the lens 29 is transmitted through the light shielding element 51 so that only the central portion of the light flux is shielded. The cross section becomes a ring-shaped light beam. The ring-shaped illumination light reaches the ink discharge head 11 via the partial reflection mirror 22, the objective lens 21, and the translucent landing member 12, and is reflected toward the landing droplet 30 by the nozzle plate 13. At this time, the central portion of the illumination light having a ring-shaped cross section is arranged so as to overlap the center of the nozzle. FIG. 10 is a diagram for explaining this situation. FIG. 10A shows a sectional view of the nozzle, and FIG. 10B shows a graph of the light intensity distribution of the illumination light irradiated in the vicinity of the nozzle. Yes. As shown in FIG. 10, the light intensity distribution irradiated to the vicinity of the nozzle 61 is in a state where the central portion is weak and irradiation to the ink filled in the nozzle 61 is suppressed. The size of the central portion where the light intensity is weak is preferably substantially equal to the size of the nozzle 61 as shown in FIG. 10, and can be adjusted by the size of the light shielding film 53 in the light shielding element 51 of FIG.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect 1)
The landing member is composed of a translucent member, and the nozzle is formed on the opposite side of the nozzle with the landing member sandwiched between the droplets landing on the landing member and the light reflected and scattered by the landed droplets. An observation optical means configured to obtain an optical image by reflecting on a nozzle plate is provided. According to this, as described in the above embodiment, the liquid droplets landing on the translucent landing member 12 and the light reflected and scattered from these liquid droplets are illuminated. Occur. The reflected and diffused light is reflected by the nozzle plate 13, passes through the translucent landing member 12 and reaches the observation optical unit 20, and an optical image is obtained by the observation optical unit 20. The liquid droplets ejected from the nozzles and landed on the landing member 12 are irradiated with light reflected by the nozzle plate 13. For this reason, even if the gap between the nozzle plate 13 of the head and the landing member 12 becomes small, the light reflected from the liquid droplets landing on the landing member 12 reaches the observation optical unit 20 and reaches the landing member. An optical image of the droplet landing on 12 is obtained. Further, when observing a droplet that has landed on the landing member 12, not the reflected light from the back side of the landing member 12, but the droplet that has landed from the front side of the landing member 12 is irradiated and landed. The light reflected by the liquid droplets is reflected by the nozzle plate 13 and passes through the translucent landing member 12. Based on the transmitted light, an optical image of a droplet landed on the landing member 12 by the observation optical unit 20 is obtained. For this reason, the three-dimensional shape of the liquid droplets that have landed on the landing member 12 can be sufficiently observed.
(Aspect 2)
In (Aspect 1), the observation optical unit includes an imaging unit that creates an optical image from the reflected light from the droplet, and an optical member that condenses the reflected light from the droplet on the imaging unit. Includes a lens system composed of a combination of an objective lens and an imaging lens, and uses a lens system in which the focal depth of the lens system is smaller than the separation distance between the landing member and the nozzle plate. According to this, as described in the above embodiment, the image of the nozzle overlaps the image of the droplet that landed on the landed member 12 or the image of the landed droplet 30 landed on the landed member 12. The problem that the situation becomes difficult to observe is solved, and the image of only the landing droplet 30 can be observed favorably on the image sensor 24.
(Aspect 3)
In (Aspect 1), there is provided a droplet that irradiates light on a landing droplet and a droplet that shines on the landing member by emitting light from the periphery of the objective lens without passing through the objective lens and landing on the landing member. Prepare. According to this, as described in the first modification of the above embodiment, the landing droplet 30 can be observed from the nozzle surface side even if the gap between the nozzle plate 13 and the landing member 12 is very small.
(Aspect 4)
In (Aspect 1), a light shielding member that does not irradiate the liquid in the nozzle with the light from the illumination unit is provided. According to this, as described in the fourth modification of the above embodiment, the illumination light for illuminating the landing droplet 30 is applied to the ink of the nozzle by suppressing the illumination light from being applied to the ink of the nozzle. This solves the problem of changing the characteristics of the lens and makes it possible to observe the same landing state as when the illumination is not performed.
(Aspect 5)
In (Aspect 2), the optical member is optically corrected for the optical thickness of the coated substrate. According to this, as described in the fourth modification of the above-described embodiment, the objective lens 21 of the observation optical unit 20 is configured to be optically corrected with respect to the optical thickness of the landing member 12, thereby The problem in the case where the image of the landing droplet 30 is blurred due to the optical aberration due to the thickness of the member 12 is solved, and a good image without blur is obtained.

DESCRIPTION OF SYMBOLS 10 Illumination 11 Ink discharge head 12 Landing object board | substrate 13 Nozzle plate 20 Observation optical unit 21 Objective lens 22 Partial reflection mirror 23 Imaging lens 24 Imaging element 25 Lamp 26 Lens 27 Fiber light guide path 28 Pinhole 29 Lens 30 Landing droplet 31 Nozzle 32 peripheral area 41 ring illumination unit 51 light shielding element 52 glass substrate 53 light shielding film 54 irradiation area 61 nozzle

JP 2008-105308 A

Claims (5)

In a droplet observation apparatus for observing a droplet discharged from a nozzle and landing on a landing member and a landed droplet,
The landing member is made of a translucent member, and the droplets that land on the landing member and the light reflected and scattered by the landing droplets are disposed on the opposite side of the nozzle with the landing member interposed therebetween. An apparatus for observing liquid droplets, characterized in that an observation optical unit configured to obtain an optical image by reflecting on a nozzle plate on which the nozzle is formed is provided. The droplet observation apparatus according to claim 1,
The observation optical unit includes an imaging unit that creates an optical image from reflected light from a droplet, and an optical member that focuses the reflected light from the droplet on the imaging unit, and the optical member is an objective lens. A droplet observation apparatus comprising: a lens system configured by a combination of imaging lenses, wherein the lens system has a focal depth smaller than a separation distance between the landing member and the nozzle plate. The droplet observation apparatus according to claim 1,
A light source that emits light from the periphery of the objective lens without being passed through the objective lens and is reflected by the nozzle plate to land on the landing member, and illumination means for illuminating the landed liquid droplet A droplet observation apparatus characterized by the above. In the droplet observation apparatus according to any one of claims 1 to 3,
A liquid droplet observation apparatus, comprising: a light shielding member that does not irradiate the liquid in the nozzle with light from the illumination unit. In the droplet observation apparatus according to claim 2,
The droplet observation apparatus, wherein the optical member is optically corrected for the optical thickness of the landing member.

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