JP2019158550A - Physical property measuring apparatus and method - Google Patents

Abstract

To enable continuous measurement of properties with a time resolution equal to or more than 100 "μs"and until a period of time equal to or more than a number "s".SOLUTION: A physical property measuring apparatus includes: a droplet generating device 10 for injecting sample liquid as a droplet 22; a strobe lighting device 14 for irradiating light intermittently; a photographing device for photographing the droplet 22 irradiated with light intermittently by the strobe lighting device 14; a target 31 to which the droplet 22 adheres; and a target drive device for moving the target 31 continuously. The physical properties of the sample liquid and/or the target 31 are measured by observing the morphology of the droplet 22 attached to the target 31.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a physical property measuring apparatus and method.

  Conventionally, it is known that the physical properties of various liquids change over time. For example, the surface tension of a liquid can change from moment to moment after a new surface is formed.

  A typical example is a surfactant solution. After a new surface is formed, the surfactant molecules diffuse in the liquid and reach the surface and are adsorbed on the surface. The phenomenon that the surface energy, that is, the surface tension becomes small is well known. Surfactant solutions are industrially very important materials.For example, in inks used in ink jet printers, when the ejected ink particles adhere to the paper, they immediately get wet and soak in the paper. In many cases, a surfactant is blended.

  Thus, for example, the surface tension of an ink droplet that changes after ejection when designing a nozzle that ejects ink in inkjet technology or knowing the wettability of ink after it adheres to paper It is extremely important to know the time variation of

  The typical time required for the surface tension change due to the above-mentioned adsorption is about μs (microseconds) to s (seconds) in a practical concentration solution in the case of surfactants often used industrially. It is. In particular, in a sufficiently practical concentration solution, it is about 10 [μs] to 100 [ms].

  On the other hand, there are some methods or apparatuses for measuring surface tension that changes with time (for example, see Patent Documents 1 to 3 and Non-Patent Documents 1 to 3). Specifically, methods such as a vibration jet method, a maximum bubble pressure method, a surface tension wave measurement method, a droplet vibration method in the air, and a method of observing a shape change of an ejected droplet with a high-speed camera are known.

JP 2011-252072 A JP2013-228242A JP 2008-46110 A

Series "Digital Printer Technology" Inkjet, 1st edition, edited by Japanese Society for Imaging Science, Tokyo Denki University Press, published on September 10, 2008, pages 2-9 Junya Yamada, Keiji Sakai, "Observation of droplet properties on the substrate by vibration excitation method" Proceedings of the 58th Joint Conference on Applied Physics, p18-013, 2011.03 Shinya Yamada, Keiji Sakai, “Observation of High-Speed Wetting Phenomenon Between Insoluble Liquids by Microdroplets” '11 .07.28-07.29 The 56th Sonics and Properties Discussion Meeting, (IEICE Technical Report) Vol. 111, no. 158, pp US2011-40-97-100, 2011.07

  However, in the conventional vibration jet method and the maximum bubble pressure method, the surface tension up to 1 [ms] cannot be measured after the liquid surface is formed, and the surface tension up to 10 [ms] is not accurate. Measurement is difficult. For example, in the vibration jet method and the maximum bubble pressure method, the time resolution is about 1 [ms] at the maximum due to the influence of the viscosity and inertia of the liquid. Furthermore, in a practical range where measurement can be performed with sufficient accuracy, the time resolution is about 10 [ms].

  In the surface tension wave measurement method, the time resolution reaches several [μs], but the measurement target must be a liquid surface having a surface elastic modulus of 100 [mN / m] or less. Is very limited. Furthermore, it is indispensable to use a laser device with good coherency having an output of several [W] or more, which increases the price and size of the apparatus.

  In addition to the surface tension described above, viscosity is also an important physical property of the liquid. However, a method for measuring the time change of the viscosity of the liquid constituting the droplet after the droplet is generated by ink jet or the like is It did not exist before.

  In addition, in the droplet vibration method in the air, the surface tension can be measured in the time region of 10 to 1000 [μs], but the measurement is performed in the time region after 1000 [μs] where the droplet trajectory becomes unstable. Have difficulty.

  In addition, the method of measuring the shape change of a droplet after it has adhered to a solid substrate such as glass, metal, or paper surface with a high-speed camera is the measurement of the contact angle created by the substrate and the droplet. It can also be used to measure dynamic interfacial tension and surface tension because it wets and spreads over time. However, a high-speed camera having a time resolution of [μs] is generally very expensive and cannot be equipped in a general-purpose experimental device, or a very powerful illumination for shooting a high-speed camera. Therefore, there is a drawback that the temperature of the droplet irradiated with light rises and the droplet evaporates instantaneously.

  In order to solve this, there is a method of shooting many droplets sequentially by strobe illumination, but when many droplets are generated per unit time, they fly in the air in order. Even if you can capture the situation, for example, if you try to observe how it adheres to and spreads on a solid substrate location, droplets that come one after the other at the same location on the substrate are fused together to form a single droplet There was a difficulty in that the shape of this could not be measured.

  The present disclosure solves the above-described conventional problems and can measure a physical property with a time resolution of 100 [μs] or more and continuously up to a time of several [s] or more. The purpose is to provide.

  Therefore, in a physical property measuring apparatus, a droplet generating device that ejects a sample liquid as droplets, a strobe illumination device that irradiates light intermittently, and a liquid that is intermittently irradiated with light by the strobe illumination device An imaging device for photographing a droplet; a target to which the droplet adheres; and a target driving device for continuously moving the target; and observing the form of the droplet adhered to the target, and the sample liquid and // Measure physical properties of the target.

  In another physical property measuring apparatus, the physical properties of the sample liquid and / or the target are further measured by observing the form of a plurality of droplets sequentially attached to the target.

  In still another physical property measuring apparatus, the target driving device keeps a constant distance from the droplet generating device to a position where the droplet reaches the target.

  In still another physical property measuring apparatus, the number of droplets ejected by the droplet generating device per unit time is 100 or less per second.

  In still another physical property measuring apparatus, the target driving device further moves the target so that the droplet attached to the target moves linearly or along a circular or spiral trajectory. Move.

  In yet another physical property measuring apparatus, the target is a liquid that does not mix with the sample liquid.

  In still another physical property measuring apparatus, the radius of the droplet in the air is R, the number of droplets ejected per unit time by the droplet generator is f, and the moving speed of the target is v. Then, the relationship of v> 2fR is satisfied.

  In still another physical property measuring apparatus, the physical property of the sample liquid and / or the target may be surface tension, interfacial tension, viscosity, elasticity, contact angle, wettability, permeability, and / or evaporation rate. is there.

  In the physical property measurement method, a sample liquid is ejected as a droplet, the droplet is adhered to a continuously moving target, and a droplet irradiated with light intermittently by a strobe illumination device is photographed, and the target is captured. The physical properties of the sample liquid and / or the target are measured by observing the form of a droplet attached to the target.

  According to the present disclosure, it is possible to provide a physical property measuring apparatus and method capable of continuously measuring a physical property with a time resolution of 100 [μs] or more and a time of several [s] or more.

It is a figure which shows the structure of the measuring device of the physical property in 1st Embodiment. It is a figure which shows the shape change of the droplet adhering to the target in 1st Embodiment. It is the photograph which image | photographed the shape change of the droplet adhering to the target in 1st Embodiment. It is a figure which shows the movement aspect of the target in 2nd Embodiment. It is a figure which shows the movement aspect of the target in 3rd Embodiment. It is a figure which shows the structure of the measuring device of the physical property in 4th Embodiment. It is the photograph which image | photographed the shape change of the droplet adhering to the target in 4th Embodiment. It is a figure which shows the structure of the measuring device of the physical property in 5th Embodiment.

  Hereinafter, embodiments will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a physical property measuring apparatus according to the first embodiment.

  In the figure, reference numeral 1 denotes a physical property measuring apparatus according to the present embodiment. The droplet 22 of the liquid 21 ejected at an initial velocity in the atmosphere or vacuum contacts the target 31. By measuring the physical properties of the objects constituting the liquid 21 and the target 31, and more specifically, the shape of the droplet 22 in contact with the target 31 and the time variation of the shape. This is a device that measures the physical properties of the liquid 21 that constitutes the droplet 22 and the object that constitutes the target 31. In the example shown in the figure, the physical property measuring apparatus 1 generates the droplet 22 generated by the droplet 22 and flies, and the shape of the droplet 22 in contact with the target 31 and the time change of the shape. It also includes a droplet observation device for observation.

  Reference numeral 11 denotes a nozzle as a droplet generation unit which is a part of the droplet generation device 10, and is preferably a commercially available glass nozzle. Then, a liquid 21 that is a sample liquid is accommodated inside the nozzle 11, and droplets 22 that are minute droplets (drops) of the liquid 21 are ejected into the atmosphere or vacuum that is the outer space. The diameter of the hole at the tip of the nozzle 11 is 5 to 200 [μm]. Further, a piezoelectric element 12 such as a piezo element is in contact with the side surface of the nozzle 11. When a voltage is applied to the piezoelectric element 12, the piezoelectric element 12 expands and presses the side surface of the nozzle 11. 11 is deformed. Thereby, the liquid 21 in the nozzle 11 is ejected as a droplet 22 from the hole at the tip of the nozzle 11.

  The liquid 21 may be made of any kind of material. For example, the liquid 21 may have conductivity or may not have conductivity. The liquid 21 is typically a surfactant solution, but may be water, oil or the like, may be an ink used in a general inkjet printer, or may be a gel-like liquid. It may be an ink, an aqueous solution, an organic solvent, silicone oil, or the like.

  In the example shown in the figure, the number of the piezoelectric elements 12 is two, and the nozzles 11 are interposed between them. However, the number of the piezoelectric elements 12 may be one or three. A plurality of the above may be used. For example, when there is one piezoelectric element 12, a jig for fixing the opposite side of the piezoelectric element 12 with the nozzle 11 interposed therebetween may be prepared. Further, when the time interval for ejecting the droplets 22 is shortened, the number of times per unit time for pressing the nozzle 11 can be increased by sequentially extending the plurality of piezoelectric elements 12 instead of simultaneously.

  Here, as a drive signal for the piezoelectric element 12, for example, by preparing an excitation voltage circuit that generates a pulsed voltage signal, the drive signal is applied to the piezoelectric element 12 to operate the piezoelectric element 12. Thereby, the droplet 22 ejected from the nozzle 11 flies in the direction indicated by the arrow A along the linear flight path. The flying speed of the droplet 22 is, for example, about 1 to 10 [m / s]. The number of droplets 22 per unit time is, for example, 100 [pieces / second] or less, but may be more than that.

  In the present embodiment, the droplet observation device includes a strobe illumination device 14 having a strobe light source and a camera 15 as a photographing device. The strobe lighting device 14 is controlled to emit light at a timing after an appropriate delay time from the rise of the voltage pulse applied to the piezoelectric element 12 that presses the nozzle 11, and intermittently emits light. As a result, the nozzle 11 is pressed and deformed, and the state in which the liquid 21 inside the nozzle 11 is ejected as a droplet 22 from the hole at the tip of the nozzle 11 is illuminated by strobe light. The camera 15 takes an image of the droplet 22 with an exposure time (time when the shutter is opened) that is longer than the time during which one light emission of the strobe light lasts and shorter than the light emission interval of the strobe light. Accordingly, the camera 15 can take an image of one droplet 22. That is, the instantaneous shape of the movement of the droplet 22 after ejection can be captured as a still image.

  At this time, if the delay time of light emission of the strobe light is fixed, images of the droplets 22 at the same position can be taken continuously after being emitted, and if the delay time is gradually increased, the flight can be performed. Further, the image of the droplet 22 whose position is gradually changed by moving the target 31 can be continuously taken.

  The droplet observation device is communicably connected to a data processing device such as a personal computer (not shown), and data such as an image taken by the camera 15 is stored in a storage means such as a semiconductor memory or a hard disk provided in the data processing device. It is desirable to be able to memorize.

  As described above, the strobe lighting device 14 according to the present embodiment, the droplet 22 is ejected and flies, and further, the process of landing on the target 31 that is a target object and showing wetness and penetration is as if it is a continuous image. In practice, however, all the droplets 22 to be illuminated are different for each light emission. For this reason, in order to observe the state of each droplet 22 clearly, the duration of the flash of the strobe light needs to be sufficiently short. For example, in order to clearly capture the shape of the droplet 22 having a diameter of 10 [μm] flying at a speed of 1.0 [m / s], the distance of at least 1/10 of the diameter of the droplet 22 is 1 [μm. It is desirable to illuminate only while moving. For this reason, the flash light emission time is desirably 1/1000000 seconds, that is, 1 [μs] or less. Furthermore, in order to observe the shape of the droplet 22 more clearly, 100 [ns] It is desirable that

Conventionally, there is a case where a strobe light source is used even when the same droplet is continuously photographed by a high-speed camera (for example, see Patent Document 4). However, the strobe illumination in this case continues to irradiate a single droplet over a relatively long period of time during which the high-speed camera continues shooting, for example, 1 [ms]. The usage is different. Such conventional strobe lighting is used for a long period of time, that is, when lighting is continuously performed with the amount of light required for shooting with a high-speed camera, including before and after the high-speed camera is shooting. This is to prevent the temperature of the injection nozzle, the substrate, and other laboratory instruments from greatly increasing. In this respect, the method of use and the purpose are completely different from the illumination method in the present embodiment in which strobe light is emitted only once at an appropriate timing for each ejection of a droplet.
JP 2004-290799 A

  When strobe light emission is performed in the present embodiment, the following advantages can be expected in droplet observation compared to the conventional method using a high-speed camera or a strobe light source in addition to this. . That is, when the phenomenon of a single droplet is observed with a high-speed camera as in the conventional case, for example, when the landing point of an object on which a droplet has landed happens to be scratched, the image is all defective. This is the result of the experiment. On the other hand, in the shooting in the present embodiment, even if a droplet lands on a defective point that rarely has a scratch or the like, the image is an image of a droplet that has landed on a good point photographed before and after. Are completely different, and an image in the case of a defect can be easily eliminated.

  In the present embodiment, the ejected droplet 22 flies in the air, reaches the target 31 disposed adjacent to the tip portion of the nozzle 11, and contacts and adheres to the target 31. In the example shown in the figure, the target 31 is a smooth solid substrate and is moved linearly at a constant speed in the direction indicated by the arrow B by an automatic stage 32 as a target driving device. That is, the target 31 performs a linear motion at a constant speed. Therefore, the droplets 22 a to 22 n (n is a natural number) attached to the target 31 move continuously with the movement of the target 31. The moving speed v is such that the droplets 22b to 22n previously adhered move a sufficient distance until the next ejected droplet 22 reaches the target 31, and the droplet 22a that has adhered next is a droplet. It is determined not to contact 22b. That is, when the number of droplets 22 ejected per unit time is f and the radius of the droplet 22 in the air is R, at least v> 2fR needs to be satisfied. More precisely, if the contact radius when the droplet 22 is attached to the target 31 is R ′, it is necessary that v> 2fR ′. For example, when n = 100 [pieces / second] and R ′ = 100 [μm], v> 1 [mm / s].

  The stroboscopic illumination device 14 and the camera 15 also measure the shape of the droplets 22a to 22n after adhering to the target 31 and the time variation thereof. From the shape, the physical properties of the droplet 22 and the target 31 to which the droplet 22 has adhered are measured. Measure physical properties determined by the combination with materials. In this actual form, the target 31 to which the droplets 22 adhere is a solid substrate. In this case, when the substrate is made of a material in which the liquid 21 of the droplet 22 does not show complete wetting, the time dependency of the contact angle can be known from the shape of the droplet 22. Since the contact angle is a function of the surface tension of the liquid 21 and the interfacial tension between the material of the target 31 and the liquid 21, they can be measured. Further, from the time change of the shape of the droplet 22, for example, when the liquid 21 contains a surfactant, the surface tension and the time of the interface tension that change with time as the surfactant is adsorbed on the surface or the interface. Changes can be measured.

  Further, by applying an electric field to the droplet 22 of the target 31 or applying a mechanical vibration, the droplet 22 is deformed from the shape of a partial sphere, and then the droplet 22 has a surface tension. It is also possible to measure the surface tension of the droplet 22 from the vibration frequency when vibrating as the restoring force.

  Next, an example of measurement of changes in the shape of the droplet 22 with time and measurement of physical properties by this will be described.

  FIG. 2 is a diagram showing a change in the shape of the droplet attached to the target in the first embodiment. In the figure, (a) is a side view and (b) is a plan view.

  As shown in the figure, the droplets 22a to 22n having a planar shape that moves in the direction indicated by the arrow B landed on and adheres to the surface of the rectangular target 31 gradually wet and spread on the target 31. The shape of the droplet 22 finally stabilized varies depending on the combination of the type of the liquid 21 as the sample and the type of the material of the target 31 as the solid substrate. That is, it is determined by the surface tension of the droplet 22, the interfacial tension between the droplet 22 and the target 31, and the surface tension of the target 31. Therefore, the surface tension or the interfacial tension can be obtained by the shape of the droplet 22 whose shape has not changed after a sufficient amount of time, particularly by the contact angle.

  Further, the surface tension or the interfacial tension that changes from time to time due to, for example, the surfactant molecules dissolved in the droplet 22 adsorbing on the surface of the droplet 22 due to the time change of the shape until reaching a stable shape. Can be requested.

  Next, experimental results conducted by the inventor using the droplet observation apparatus in the present embodiment will be described.

  FIG. 3 is a photograph of the change in shape of the droplet attached to the target in the first embodiment.

  In the figure, the droplet 22 at the left end is a pure water droplet 22 immediately after landing on a clean glass substrate as a target 31, and the central droplet 22 is ejected immediately before landing. The right end is the droplet 22 transferred rightward, and the right end is the droplet 22 transferred rightward after being ejected and landed. At this time, the time interval of ejection of the droplet 22 is 0.1 [s]. From this figure, it can be seen that the contact angle decreases immediately after landing, and the volume of the droplet 22 decreases due to evaporation. This figure is a photograph taken at a certain moment, but it is of course possible to observe as a smooth moving image the droplet 22 landing and getting wet and spreading and being transferred to the right.

  As described above, the physical property measurement apparatus 1 according to the present embodiment includes the droplet generation device 10 that ejects the liquid 21 as the droplet 22, the strobe illumination device 14 that intermittently emits light, and the strobe illumination device 14. A droplet 15 attached to the target 31 is provided with a camera 15 that photographs the droplet 22 irradiated with light intermittently, a target 31 to which the droplet 22 adheres, and an automatic stage 32 that moves the target 31 continuously. The physical properties of the liquid 21 and / or the target 31 are measured by observing the 22 forms.

  Further, in the physical property measurement method according to the present embodiment, the liquid 21 is ejected as the droplet 22, the droplet 22 is attached to the continuously moving target 31, and light is intermittently irradiated by the strobe illumination device 14. The physical properties of the liquid 21 and / or the target 31 are measured by photographing the formed droplet 22 and observing the form of the droplet 22 attached to the target 21.

  Further, the physical properties of the liquid 21 and / or the target 31 are measured by observing the form of the plurality of droplets 22 that are sequentially attached to the target 31. Further, the number of droplets 22 ejected by the droplet generation device 10 per unit time is 100 or less per second. Furthermore, the automatic stage 32 moves the target 31 so that the droplet 22 attached to the target 31 moves linearly. Further, assuming that the radius of the droplet 22 in the air is R, the number of the droplets 22 ejected per unit time by the droplet generator 10 is f, and the moving speed of the target 31 is v, the relation of v> 2fR is satisfied. Satisfied. Furthermore, the physical properties of the liquid 21 and / or the target 31 are surface tension, interfacial tension, viscosity, elasticity, contact angle, wettability, permeability, and / or evaporation rate.

  Thereby, the physical properties of the liquid 21 and / or the target 31 can be continuously measured with a time resolution of 100 [μs] or more and a time of several [s] or more.

  Next, a second embodiment will be described. In addition, about the thing which has the same structure as 1st Embodiment, the description is abbreviate | omitted by providing the same code | symbol. The description of the same operation and the same effect as those of the first embodiment is also omitted.

  FIG. 4 is a diagram showing how the target moves in the second embodiment. In addition, in the figure, (a) is a figure which shows an example without a wiping mechanism, (b) is a figure which shows an example provided with a wiping mechanism.

  While the planar shape of the target 31 is rectangular in the first embodiment, the target 31 in the present embodiment is a smooth solid substrate, as shown in FIG. 4 (a). The planar shape is circular. The automatic stage 32 as a target drive device rotates the target 31 in the direction indicated by the arrow C at a constant rotational speed. Then, the droplet 22 ejected from the nozzle 11 is landed at a position away from the center of the rotational movement as indicated by the X mark. Thereby, the droplets 22a to 22n attached to the target 31 move at a constant rotational speed in the direction indicated by the arrow C along the circular orbit 33 centering on the center of the rotational motion. Next, the ejected droplet 22 reaches the same position and becomes a droplet 22a attached to the target 31, but the droplet 22b ejected one time before and attached to the target 31 follows the circular orbit 33. It has moved a predetermined distance. Thus, the droplets 22 a to 22 n ejected one by one and attached to the target 31 are arranged on the circular orbit 33.

  If the droplet 22n completely evaporates within the time before the target 31 rotates once, the shape change of the droplets 22a to 22n can be continuously measured by this method.

  On the other hand, the droplet 22 may contain a non-volatile component such as a pigment. At this time, a non-volatile component remains on the target 31 which is a solid substrate. When the droplet 22 newly adheres to the portion where the non-volatile component remains attached, the shape of the adsorption may change due to the influence. In order to avoid this, the wiping mechanism 34 is provided in the example shown in FIG. By wiping and removing the residue on the target 31 by the wiping mechanism 34, the target 31 can be kept clean.

  Since the configuration and operation of other points are the same as those in the first embodiment, description thereof is omitted.

  Thus, in the present embodiment, the automatic stage 32 moves the target 31 so that the droplet 22 attached to the target 31 moves along a circular orbit.

  Next, a third embodiment will be described. In addition, about the thing which has the same structure as 1st and 2nd embodiment, the description is abbreviate | omitted by providing the same code | symbol. Also, the description of the same operations and effects as those of the first and second embodiments is omitted.

  FIG. 5 is a diagram showing how the target moves in the third embodiment.

  In the second embodiment, the target 31 having a circular planar shape is rotated, whereas in the present embodiment, the target 31 having a circular planar shape is rotated and moved in the horizontal direction. ing. Specifically, the automatic stage 32 as a target driving device causes the target 31 to move linearly at a constant speed in the direction indicated by the arrow B and to rotate at a constant rotational speed in the direction indicated by the arrow C. . Then, the droplet 22 ejected from the nozzle 11 is landed at a position away from the center of the rotational movement as indicated by the X mark. Then, the droplets 22 a to 22 n continuously attached to the target 31 are arranged along the spiral trajectory 35.

  Thus, since the droplets 22a to 22n are arranged along the spiral orbit 35 longer than the circular orbit 33 in the second embodiment, even if the wiping mechanism 34 is not provided, it takes a long time. Thus, the droplets 22a to 22n can be observed. For example, if the radius of the target 31 is 5 [cm] and the radial distance between the spirals is 100 [μm], the total extension length of the spiral is 30 [m] or more, and the attachment is made at this time. If the distance between the droplets 22 to be applied is 100 [μm], the total number of droplets 22 that can be attached is 300,000, and if 30 droplets 22 are attached per second, 10 , 000 [seconds] ≈ Continuous measurement over 3 hours or more.

  Since other configurations and operations are the same as those in the first and second embodiments, the description thereof is omitted.

  Thus, in the present embodiment, the automatic stage 32 moves the target 31 so that the droplet 22 attached to the target 31 moves along the spiral trajectory.

  Next, a fourth embodiment will be described. In addition, about the thing which has the same structure as the 1st-3rd embodiment, the description is abbreviate | omitted by providing the same code | symbol. Explanation of the same operations and effects as those of the first to third embodiments is also omitted.

  FIG. 6 is a diagram showing a configuration of a physical property measuring apparatus according to the fourth embodiment.

  The physical property measuring apparatus 1 in the present embodiment includes a sensor 16 as a measuring apparatus that measures the surface position of the target 31. The sensor 16 is, for example, a laser range finder, and measures the surface position of the target 31 at the location where the droplet 22 ejected from the nozzle 11 lands, specifically, the vertical position. In addition to the automatic stage 32, the physical property measuring apparatus 1 according to the present embodiment includes a position control device 36 as a target driving device. Based on the data of the surface position of the target 31 measured by the sensor 16, the position control device 36 drives the target 31 in the vertical direction as indicated by the arrow D to determine the surface position of the target 31. The position where the droplet 22 contacts the surface of the target 31 is stably held at a fixed position as viewed from the nozzle 11 without depending on the unevenness of the surface of the target 31. That is, control is performed so that the distance from the hole at the tip of the nozzle 11 to the position where the droplet 22 contacts the surface of the target 31 does not change.

  Thereby, even if the surface of the target 31 that is the object to be measured is uneven, the shape of the droplet 22 can be stably observed. Even if the surface of the target 31 is, for example, a paper surface with many irregularities or the surface of a leaf, it is possible to measure physical properties such as the wetting and spreading speed and the penetration speed of the droplet 22. .

  Next, experimental results conducted by the inventor using the droplet observation apparatus in the present embodiment will be described.

  FIG. 7 is a photograph of a change in shape of a droplet attached to a target in the fourth embodiment.

  In the figure, the time change of the shape of the ethylene glycol droplet 22 landed on the general-purpose printing paper as the target 31 is shown. In the present embodiment, it is possible to observe how the droplets 22 gradually permeate the paper. The picture shows a picture taken at a certain moment, but it is of course possible to observe a smooth moving image of the droplet 22 landing and then being transported while penetrating into the paper. It is.

  Since the configuration and operation of other points are the same as those in the first to third embodiments, description thereof will be omitted.

  Thus, in the present embodiment, the position control device 36 keeps the distance from the droplet generation device 10 to the position where the droplet 22 reaches the target 31 constant.

  Next, a fifth embodiment will be described. In addition, about the thing which has the same structure as 1st-4th embodiment, the description is abbreviate | omitted by providing the same code | symbol. Explanation of the same operations and effects as those of the first to fourth embodiments is also omitted.

  FIG. 8 is a diagram showing a configuration of a physical property measuring apparatus according to the fifth embodiment.

  In the present embodiment, the target 31 is a liquid. The liquid is a liquid that does not mix with the liquid 21 of the droplet 22. For example, when the liquid 21 of the droplet 22 is pure water, the target 31 is an oil that does not mix with pure water, for example, hexadecane. It is.

  And the target 31 which is a liquid is accommodated in the container 37 with which the upper surface was open | released, and circulates through the circulation flow path 38 connected to the bottom part of this container 37. FIG. A pump 39 as a target drive device is disposed in the middle of the circulation flow path 38, and the target 31 flows and circulates in the direction indicated by the arrow E by the pump 39. As a result, the target 31 that is the liquid contained in the container 37 moves linearly at a constant speed in the direction indicated by the arrow E, and the surface 31a of the target 31 that is the liquid level also moves in the direction indicated by the arrow E. Move linearly at a constant speed. The droplet 22 ejected from the nozzle 11 also adheres to the surface 31a of the target 31 and moves linearly at a constant speed in the direction indicated by the arrow E. For convenience, the drawing of the strobe lighting device 14 and the camera 15 which are droplet observation devices is omitted in the drawing.

  Here, since the droplet 22 is sufficiently small, even if the specific gravity of the liquid 21 of the droplet 22 is smaller than the specific gravity of the target 31 that is the liquid to which it adheres, it does not settle due to gravity after adhering to the surface 31a. The liquid surface stays on the surface 31a. At this time, the shape of the droplet 22 is such that the surface tension of the liquid 21 (sample liquid) constituting the droplet 22, the surface tension of the liquid constituting the target 31, and between the sample liquid and the liquid constituting the target 31. Determined by the interfacial tension.

In the figure, F is a principal part enlarged side view showing the droplet 22b attached to the surface 31a of the target 31 and the surrounding surface 31a. By observing the shape of the droplet 22b, the angle θ of the droplet 22b on the upper side of the surface 31a and the angle φ of the droplet 22b on the lower side of the surface 31a can be measured. When the surface tension of the sample liquid is σD, the surface tension of the liquid constituting the target 31 is σS, and the interfacial tension between the sample liquid and the liquid constituting the target 31 is σI, the following equation (1) And the relationship of (2) is materialized.
σS = σD cosθ + σI cosφ Expression (1)
σD sinθ = σI sinφ Expression (2)
From the above formulas (1) and (2), the ratio between σD, σS, and σI can be uniquely determined.

  When the liquid 21 constituting the liquid droplet 22 contains a surfactant, the shape of the liquid droplet 22 changes due to changes in the surface tension and interfacial tension over time, and the ratio between σD, σS, and σI is determined by the measurement. Time change can be determined. Further, at that time, if a liquid that does not spread on the surface 31a and the surface tension σS does not change with time is selected as the liquid constituting the target 31, then σI and σD The value can be uniquely determined. For example, hexadecane corresponds to the type of liquid constituting the target 31.

  Since the configuration and operation of other points are the same as those in the first to fourth embodiments, description thereof will be omitted.

  Thus, in the present embodiment, the target 31 is a liquid that does not mix with the liquid 21.

  As described above, according to the physical property measuring apparatus and method of the present disclosure, the target 31 is not necessarily a good flat surface or does not have good smoothness, such as a printing paper. In addition, the landing and adhesion of the droplet 22 can be continued stably. In addition, by sequentially viewing a large number of images while gradually sweeping the time, wetting and spreading on the target 31 after adhesion and penetration into the target 31 are as if continuous shooting of one phenomenon. It can be observed as a result. At this time, even if the landing location of the target 31 is rarely damaged, it is possible to exclude a defective observation image by comparing it with a large number of good observation examples before and after that. In other words, the average of a large number of phenomena It is very suitable for observing the dynamic interaction between the target 31 having no smoothness and the droplet 22 in that the moving image of the target can be observed.

  Furthermore, the unevenness of the target 31 is detected, the information is fed back to drive the position of the target 31, thereby stabilizing the observation position of the droplet 22 by the camera 15, so that the surface of the target 31 has considerable unevenness. Even if it does, it becomes possible to observe the droplet 22 adhering to it stably, and, for example, the behavior of the microdroplet of the pesticide which spreads or permeates the leaf of the plant is stabilized. Can be observed. The target 31 is not limited to the surface of a plant, and can be applied to, for example, observing the penetration and wettability of a drug on human skin.

  Further, the physical property measuring apparatus and method in the present disclosure are suitable for observing dynamic behavior such as wetting spread, penetration, and drying of paint such as paint on a wall of a house having an uneven surface, Thereby, important information can be provided for prediction of the process of painting with the paint sprayed using a spray or the like.

  Furthermore, it is suitable for observing dynamic behavior such as wetting and spreading of glaze applied to the porous ceramic surface at the unglazed stage in the production process of pottery or porcelain.

  Furthermore, it is also effective for observing the manufacturing process of a printed electronic device manufactured using an ink jet or other fine line drawing technology.

  It should be noted that the disclosure of the present specification describes features related to preferred and exemplary embodiments. Various other embodiments, modifications and variations within the scope and spirit of the claims attached hereto can naturally be conceived by those skilled in the art by reviewing the disclosure herein. is there.

  The present invention can be applied to a physical property measuring apparatus and method.

DESCRIPTION OF SYMBOLS 1 Physical property measuring device 10 Droplet production device 14 Strobe illumination device 15 Camera 21 Liquid 22, 22a, 22b, 22n Droplet 31 Target 32 Automatic stage 33 Circular orbit 35 Spiral orbit 36 Position control device 39 Pump

Claims (9)

A droplet generator for ejecting sample liquid as droplets;
A strobe lighting device that emits light intermittently;
A photographing device for photographing droplets irradiated with light intermittently by the strobe lighting device;
A target to which the droplets adhere;
A target driving device for continuously moving the target,
An apparatus for measuring physical properties, wherein the physical properties of the sample liquid and / or the target are measured by observing the form of a droplet attached to the target.   The physical property measuring apparatus according to claim 1, wherein the physical property of the sample liquid and / or the target is measured by observing the form of a plurality of droplets sequentially attached to the target.   The physical property measurement device according to claim 1, wherein the target driving device maintains a constant distance from the droplet generation device to a position where the droplet reaches the target.   The physical property measuring apparatus according to claim 1, wherein the number of droplets ejected by the droplet generating device per unit time is 100 or less per second.   The said target drive device moves the said target so that the droplet adhering to the said target may move linearly, or may move along a circular or spiral trajectory. Measuring device for physical properties described in 1.   The physical property measuring apparatus according to claim 1, wherein the target is a liquid that does not mix with the sample liquid. When the radius of the droplet in the air is R, the number of droplets ejected by the droplet generator per unit time is f, and the moving speed of the target is v,
v> 2fR
The physical property measuring apparatus according to claim 1, wherein the physical property is satisfied.   The physical property of the sample liquid and / or the target is surface tension, interfacial tension, viscosity, elasticity, contact angle, wettability, permeability, and / or evaporation rate. The physical property measuring device described. Sample liquid is ejected as droplets,
Attach the droplet to a continuously moving target,
Take a picture of a droplet that was intermittently irradiated with light by a strobe lighting device,
A method for measuring physical properties, wherein the physical properties of the sample liquid and / or the target are measured by observing the form of a droplet attached to the target.