JP2010060379A - Contact angle measuring system and contact angle measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contact angle measuring system of the smallest necessary configuration and capable of suitably measuring a contact angle by simply and rapidly determining a more accurate contact point and to provide a contact angle measuring method. <P>SOLUTION: The contact angle measuring system includes: a dispenser (18) for dropping droplets of an object to be measured on the surface of a substrate (12); a boundary discrimination member disposed on the surface of the substrate to discriminate the boundary between the substrate and a droplet; a camera unit (22) for photographing the droplet and the boundary discrimination member in a single image from a horizontal or oblique direction to the substrate; and an image processing device (26) for determining the boundary between the surface of the substrate and the droplet from the image of the boundary discrimination member acquired from the camera unit, and determines the contact angle of the droplet to the substrate based on the boundary. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a contact angle measurement system and a contact angle measurement method, and more particularly to a contact angle measurement technique used for evaluating wettability of a solid surface.

  Control of wettability of a solid surface is a very important issue in many industrial fields such as medical treatment, food, printing, automobiles and semiconductors. For example, wettability evaluation between ink for ink jet recording apparatus and media and members such as film and paper as recording media, wettability evaluation between conductive ink, insulating ink and circuit board or member, RGB ink and color There are wettability evaluations with filter substrates.

  As shown in FIG. 17, the wettability on the solid surface 200 is generally expressed by the contact angle θ of the droplet 202, and the droplet 202 is dropped on the sample surface (solid surface) 200 for measurement. There is a method of observing with a magnifying optical system such as a microscope and measuring the angle at which the droplet 202 contacts the sample surface 200. The “contact angle” refers to the angle θ between the solid surface 200 and the tangent 210 drawn to the droplet 202 at the three-phase contact point 208 of the solid 204, the droplet 202, and the gas 206 and the solid surface 200. Say. There is a method of taking a photograph of a droplet on a solid, which has been a method for measuring a contact angle from the past, and a method of acquiring an image of a droplet on a solid with a CCD camera and processing data with a computer in recent years.

  In the method of photographing a droplet on a solid, a sample obtained by dropping the droplet 202 on the surface 200 of the flat solid 204 when measuring the contact angle θ is parallel to the solid surface 200 by a magnifying optical system such as a microscope. The angle at which the liquid droplet 202 is in contact with the solid surface 200, that is, the contact angle θ, is observed from the lateral direction that is the direction. However, in such a method, the contact point of the three phases of the solid 204, the droplet 202, and the air (gas) 206 (hereinafter simply referred to as “contact point”) may be described because of the combination of the samples used and the refractive index. .) It was difficult to discriminate 208. In order to solve this problem, a method of automatically recognizing a contact point using an image analysis program, a method of determining a contact point by adjusting a light source position, a light amount, and the like have been adopted.

On the other hand, in recent years, methods for observing droplets on a sample from above have been proposed (Patent Documents 1 and 2). Also, the height of the droplet on the sample is measured from above using a laser microscope, and the diameter of the droplet is measured by any means, and the contact angle of the droplet is determined from the value of the height and diameter of the droplet. Has been proposed (Patent Document 3).
JP-A-1-126523 JP-A-5-232009 JP-A-8-50088

  However, in the automatic recognition of the contact point by the above-described image analysis program, there is a case where the contact point 208 is erroneously determined in the case shown in FIG. In the figure, a state in which the droplet 202 is dropped from the dispenser 211 onto the surface 200 of the substrate (solid) 204 is photographed with a CCD camera from the horizontal direction with respect to the substrate 204, and the photographed image is displayed on the monitor. is there. In FIG. 18, the apparent surface (the surface that can be seen only in the photographed image) 212 is reflected on the substrate 204 by the influence of light reflection or refraction even though the position shown by the one-dot broken line is the actual surface 200 of the substrate 204. The surface 200 may be mistakenly recognized, and the position denoted by reference numeral 214 may be recognized as a contact point between the substrate 204, the droplet 202, and the gas 206.

  In such a case, it is necessary to adjust image analysis parameters such as setting a threshold (a boundary value between a black part and a white part on the image) for discriminating contact points. In addition to the variation in measured values, there is a problem that it takes time for one measurement and analysis. Further, in order to further automate and speed up such adjustment, a more advanced image processing program is required. On the other hand, it is difficult to clarify the contact point on the sample surface or the like with high reflection by the measure by adjusting the light amount, and when the light amount is too low, there is a problem that the shape of the droplet itself is difficult to discriminate.

  FIG. 19 shows a result of determining the contact point between the substrate 204, the droplet 202, and the gas 206 when the threshold is manually set. When the threshold is set manually, measurement variation as shown in the figure occurs. In FIG. 19, the apparent surface of the substrate 204 obtained from the identified contact point 220 is illustrated by reference numeral 222, and the apparent surface of the substrate 204 obtained from the identified contact point 224 is illustrated by reference numeral 226. To do.

  The contact angle at the contact point 220 is 112.9 °, the contact angle at the contact point 224 is 105.0 °, and this value is 20 vs. the contact angle 86.3 ° on the actual surface 200 of the substrate 204. An error of about 30 ° is included.

  FIG. 20 illustrates a case where the contact point 208 is incorrectly determined in automatic recognition by the image analysis program. The apparent surface of the substrate 204 by the determined measurement point 230 is the surface indicated by reference numeral 232, and the contact angle is 99.1 °. This value has an error of 10 ° or more with respect to the contact angle of 86.3 ° on the actual surface 200 of the substrate 204.

  In the methods described in Patent Documents 1 and 2, a droplet having a known volume or mass is attached to a sample, the diameter of the droplet is measured from above, and two parameters of the volume or mass and the measured diameter are set. To calculate the contact angle. In such a method, since the droplets are quantitatively discharged onto the sample by a syringe or a spray, it is difficult to uniformly deposit droplets of a uniform volume or mass on the sample, and individual droplets vary. Arise. Further, during measurement of the diameter of the droplet, the physical quantity of the droplet changes from a known value due to evaporation or the like. As a result, the error in the measurement of the contact angle becomes large, and there is a problem in terms of accuracy.

  Further, the measuring method described in Patent Document 3 has a problem that the contact angle measuring device itself becomes large, and an extremely expensive device called a laser microscope is required.

  The present invention has been made in view of such circumstances, and a contact angle measurement system and a contact angle that can easily and quickly determine an accurate contact point and realize a preferable contact angle measurement with a minimum necessary apparatus configuration. An object is to provide a measurement method.

  In order to achieve the above object, a contact angle measurement system according to the present invention discriminates a drop means for dropping a droplet to be measured on the surface of a substrate, and a boundary between the substrate and the droplet on the surface of the substrate. And photographing means for photographing the droplet and the boundary discriminating member from a horizontal direction or an oblique direction with respect to the substrate so that the droplet and the boundary discriminating member are within the same screen. An imaging unit; a boundary determining unit that determines a boundary between the substrate and the droplet from an image of the boundary determining member obtained by the imaging unit; and the substrate with respect to the substrate at the boundary determined by the boundary determining unit Contact angle deriving means for obtaining the contact angle of the droplet.

  According to the present invention, the surface of the substrate can be recognized simply and quickly, and the contact angle on the substrate can be accurately obtained. Further, by eliminating the need for a highly functional image analysis program or manual adjustment by the measurer, a more simplified contact angle measurement system can be configured.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Configuration of contact angle measurement system]
FIG. 1 is an overall configuration diagram of the contact angle measurement system described above. A contact angle measurement system 10 shown in FIG. 1 includes a substrate support portion 14A that supports a substrate 12 onto which a droplet (not shown) to be measured is dropped from the back side opposite to the surface 12A onto which the droplet is dropped. In addition, an XY stage 14 that horizontally moves the substrate 12 in the X direction and the Y direction, a dispenser 18 that includes a discharge needle 16 that drops a droplet to be measured on the substrate 12, and a light source that irradiates the surface 12A of the substrate 12 with light. A unit 20, a camera unit 22 for photographing the surface 12A of the substrate 12 from the horizontal direction, a vertical movement mechanism 24 for moving the dispenser 18 and the camera unit 22 together in the horizontal direction and adjusting the height of the camera unit 22. An image processing device (PC) 26 that performs predetermined image processing on the image data obtained by the camera unit 22 and an image processed image are displayed. A monitor 28 which is configured to include a user interface of the image processing apparatus 26 (a keyboard 30 and mouse 32).

  The substrate 12 of this example is a silicon substrate coated with a fluororesin film, and in this example, a case will be described in which the contact angle of pure water and ink (ink generally used in an ink jet recording apparatus) with respect to the substrate 12 is measured. The contact angle measurement system shown in this example can use a wide variety of substrates such as a metal substrate, a resin substrate, a glass substrate, and a liquid crystal polymer, and the surface treatment (water repellent film) of the substrate 12 is a fluororesin film. In addition, eutectoid plating including a fluorine film may be used, and a hydrophilic material such as a titanium oxide coating film can be evaluated. The fluorine film includes PTFE (polytetrafluoroethylene (tetrafluoride)), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), and the like.

  In addition to pure water, the liquid to be measured can be a liquid used in a general industrial field, or a biological material (cell, medicine) used in the medical field.

  The XY stage 14 is a means for relatively moving the dispenser 18 and the substrate 12 in order to change the dropping point of the droplet on the substrate 12.

  The dispenser 18 is made of glass, has a syringe barrel capacity of 1 milliliter, and is configured to be able to adjust the amount of liquid droplets dropped on the surface to be measured of the substrate 12. The amount of droplets dropped on the surface to be measured of the substrate 12 can be appropriately selected depending on the object to be measured (substrate) and the type of the droplet, and JIS R 3257 (1999) “Wetting of substrate glass surface”. 1 microliter or more and 4 microliter or less is suitable according to the “ability test method”.

  The dispenser 18 is supported integrally with the camera unit 22 and is configured to be movable along the guide member.

  The light source unit 20 is means for irradiating the droplets on the substrate 12 with light necessary for photographing by the camera unit 22, and is configured so that the amount of light can be varied in multiple stages. It is preferable that the light amount adjustment of the light source unit 20 is automatically adjusted according to a command signal sent from the camera unit 22 or the image processing device 26. Further, visible light such as white light is applied as the light source type.

  Although detailed illustration of the configuration of the camera unit 22 is omitted, the camera unit 22 includes an optical system that includes a photographic lens, a CCD image sensor that converts a subject image into a photographic signal, and a photographic signal obtained from the CCD image sensor. Includes a signal processing unit that performs predetermined signal processing, a memory that stores image data that has been subjected to predetermined signal processing, and an external interface that is connected to the image processing device 26 (external device). ing.

  The camera unit 22 functions as means for capturing a still image of the droplet dropped on the substrate 12 in accordance with a command signal sent from an external control device and sending the still image data to the image processing device 26. Yes. The image processing device 26 may be applied as an external control device so that shooting is performed while viewing a through image displayed on the monitor 28. The image processing device 26 includes the signal processing unit and the memory described above. The camera unit 22 may include an imaging system and an external interface.

  Further, the camera unit 22 may be provided with a display device such as an electronic viewfinder so that the photographer can manually take a picture while confirming the image displayed on the display device.

  The relative positional relationship between the camera unit 22 and the dispenser 18 is fixed, and the camera unit 22 is focused on an imaging area including the tip of the ejection needle 16 and the landing position of the droplet dropped from the ejection needle 16 on the substrate 12. The optical system is adjusted. For example, when a droplet is dropped on the end of the substrate 12, the XY stage 14 is operated to move the end (dropping point) of the substrate 12 directly below the dispenser 18, and the end of the substrate 12 is moved from the dispenser 18. Drop droplets on the part.

  The vertical movement mechanism 24 includes a support member that supports the camera unit 22 and the dispenser 18, and a vertical slide mechanism that moves the support member in the vertical direction. The vertical movement mechanism 24 adjusts the height of the surface 12 A of the substrate 12 and the dispenser 18. It functions as a means to perform.

  The vertical movement mechanism 24 shown in FIG. 1 adjusts the height of the camera unit 22 (and the dispenser 18) while fixing the relative positional relationship between the dispenser 18 and the camera unit 22 according to the thickness of the substrate 12. It is configured as follows.

  In the contact angle measurement system shown in FIG. 1, the above-described XY stage 14, dispenser 18, light source unit 20, and camera unit 22 are fixed to a fixed base 25.

  The image processing device 26 performs image analysis processing on the photographing data of the droplet on the substrate 12 obtained by the camera unit 22 and sends a video signal for displaying the photographed image of the droplet to the monitor 28. Further, the image processing device 26 functions as means for calculating the contact angle of the droplet with respect to the substrate 12 based on the photographing data.

  That is, the image processing device 26 can execute a program (software) for performing image processing (image analysis) necessary for contact angle measurement, and from the captured image, the boundary surface between the substrate 12 and the measurement target droplet (substrate 12 and A function of automatically recognizing a contact point between a measurement target droplet and air, a function of correcting the boundary surface, a function of calculating a contact angle based on the boundary surface, and the like.

  FIG. 1 illustrates a form in which the image processing apparatus 26 and the camera unit 22 are connected by a cable using a general-purpose interface such as USB (Universal Serial Bus) or Ethernet (registered trademark), but a wireless connection form such as a wireless LAN is illustrated. May be applied. It is also possible to configure the image processing device 26 and the monitor 28 integrally with the camera unit 22.

  FIG. 2 shows a still image immediately before the droplet 40 is dropped from the tip of the ejection needle 16 projected on the monitor 28 of FIG. As shown in FIG. 2, the image projected on the monitor 28 has an apparent surface 42 at a position different from the actual surface 12A due to reflection and refraction. The contact angle measurement system and the contact angle measurement method shown in this example are configured so that the contact point can be accurately recognized even when the apparent surface 42 exists, and accurate contact angle measurement is realized. ing.

[Explanation of contact angle measurement method]
Next, a method for measuring the contact angle will be described in detail. In the contact angle measurement method shown in this example, a contact serving as a reference for discriminating contact points of the substrate 12, the measurement target droplet, and the air in the vicinity of the measurement target droplet in the same plane as the measurement target droplet. A point discriminating member (boundary discriminating member) is arranged, a contact point, that is, a boundary surface between the substrate and the liquid droplet (actual surface of the substrate 12) is determined based on a photographed image of the contact point determining member, and the boundary surface is used as a reference. The contact angle of the droplet to be measured is calculated as follows.

  In the following, a case where a liquid that is the same type as the measurement target droplet and has a sufficiently small droplet amount with respect to the measurement target droplet is applied as the contact point determination member will be described. Specifically, the drop amount of the liquid droplet to be measured is 2 μl (microliter), and the drop amount of the contact point determination member is 0.05 μl (microliter) which is 1/40 of the drop amount of the liquid droplet to be measured. ).

  FIG. 3 shows an image displayed on the monitor 28 (see FIG. 1), in which an image 50 of a droplet to be measured and an image 52 of a contact point discriminating member on the surface 12A (shown by a one-dot broken line) of the substrate 12 are displayed. It is. As shown in FIG. 3, the measurement target droplet image 50 includes an actual droplet image 50 </ b> A and a mirror image 50 </ b> B of reflection droplets. Also, the contact point determination member image 52 includes an actual contact point determination member image 52A and a mirror image 52B of the contact point determination member by reflection.

  An image 52 of the contact point determination member shown in FIG. 3 has a horizontally long elliptical shape that is line symmetric with respect to the horizontal direction, and the long axis can be regarded as the actual surface 12 </ b> A of the substrate 12. The contact point discriminating member has a liquid amount sufficiently smaller than the liquid droplet to be measured, and since the lower contour line of the image 52 does not reach the apparent surface 42, the entire contour can be grasped. Accordingly, the midpoint of the short axis (the midpoint of the maximum height) in the image 52 of the contact point determination member is obtained, and a line parallel to the horizontal direction passing through the midpoint becomes a line symmetry axis that is the long axis.

  That is, in the contact angle measurement method shown in this example, the line symmetry axis in the image 52 of the contact point determination member is regarded as the surface 12A of the substrate 12 (the boundary surface between the substrate 12 and the measurement target droplet), and the line symmetry axis is measured. By applying to the target droplet image 50, the contact angle at the contact point between the measurement target droplet, the substrate 12, and the gas 54 is calculated. Further, the size (drop amount) of the contact point determination member is determined so that the entire contact point determination member image 52 can be recognized as a captured image.

  Specifically, on the screen displayed on the monitor 28, the mouse 32 (see FIG. 1) is operated to draw the line symmetry axis of the image 52 of the contact point determination member, and this line symmetry axis is used as the surface 12A of the substrate 12. It is set on the image analysis program and the contact angle is automatically calculated. It is also possible to directly measure from an image displayed on the screen or a printed image.

  FIG. 4 illustrates a state in which the symmetry axis 60 is drawn on the screen projected on the monitor 28. The contact angle obtained based on the symmetry axis 60 shown in FIG. 4 is 86.3 °. FIG. 4 shows the surfaces 62 and 64 of the substrate 12 (the apparent surface of the substrate 12 appearing in the photographed image) automatically recognized by the image analysis program. By changing the setting of the threshold value or the like in automatic recognition by the image analysis program, the position indicated by reference numeral 62 or the position indicated by reference numeral 64 is recognized as an apparent substrate surface. However, in any case, the surface of the substrate 12 is not accurately recognized.

  The contact angle calculation value α when the position indicated by reference numeral 62 is recognized as the surface of the substrate 12 is 112.9 °, and the calculated contact angle when the position indicated by reference numeral 64 is recognized as the surface of the substrate 12 is 105.0 °.

  The shape of the measurement target droplet image 50 shown in FIGS. 3 and 4 is also affected by the position on the substrate 12 (distribution of reflected light on the surface 12A of the substrate 12) and changes. In particular, a substrate with high reflection (a substrate that has been subjected to surface treatment with high reflection) results in an image in which it is difficult to visually determine contact points. Therefore, it is necessary to grasp the difference in the shape of the measurement target droplet image 50 due to the difference in position on the substrate 12.

  FIG. 5A shows measurement conditions when a difference in the shape of the image 50 of the measurement target droplet due to a difference in distance from the end surface of the substrate 12 is measured using the contact angle measurement system 10 shown in FIG. Illustrated. A measurement point (0 cm) indicated by reference numeral 70A is an end face of the substrate 12 on the camera unit 22 side, a measurement point indicated by reference numeral 70B is a position 3 cm from the end face (0 cm) of the substrate 12 to the inside of the substrate 12, and reference numeral 70C. The measurement point indicated by is a position 5 cm from the end face (0 cm) of the substrate 12 to the inside of the substrate 12.

  As shown in FIG. 5B, in the contact angle measurement system 10 shown in FIG. 1, the distance between the dispenser 18 and the camera unit 22 is fixed. Therefore, in the above-described measurement, the camera unit 22 and the measurement point 70A. The distance of ~ 70C is fixed.

  FIG. 6 shows a captured image 80A of the measurement point 70A in FIG. At the measurement point 70A, only the reflection from the rear side of the droplet to be measured is present, and the shape is similar to the shape of an actual droplet. The boundary surface obtained by automatically discriminating the captured image 80A shown in FIG. 6 by the image analysis program is a position denoted by reference numeral 82A. On the other hand, the boundary surface determined using the image 52 of the boundary position determination member is a position denoted by reference numeral 84A. The contact angle obtained by the image analysis program is 87.3 °, and the contact angle value obtained by the contact angle measurement method of this example is 86.1 °.

  FIG. 7 shows an image 80B of the measurement point 70B in FIG. FIG. 8 shows an image 80C of the measurement point 70C in FIG. The image 80B shown in FIG. 7 and the image 80C shown in FIG. 8 are affected not only by the back of the immediate fixed points 70B and 70C but also by the reflection from the front, and thus are recognized as a substantially spherical shape unlike the actual droplet shape. The position of the boundary point automatically determined by automatic recognition will vary greatly depending on the parameter setting or the like.

  On the other hand, the boundary surface determined using the image 52 of the boundary position determination member is a position denoted by reference numeral 84B in FIG. 7 and reference numeral 84C in FIG. 8, and is a certain position that can be allowed without variation. Be recognized. That is, according to the contact angle measurement method shown in this example, the boundary surface between the substrate 12 and the measurement target droplet can be reliably recognized with high reproducibility at any position within the substrate 12.

  The reflection by the surface of the board | substrate 12 mentioned above can be made small by restrict | squeezing the light quantity radiated | emitted from a light source unit (refer FIG. 1). That is, by reducing the light amount of the light source unit, the apparent surface 42 shown in FIG. 3 may move upward to approach the actual surface 12A, and the actual surface 12A can be confirmed. When there is no discriminating member, it is impossible to determine how far the moving substrate surface (substrate surface adjusted by the amount of light) is moved.

  On the other hand, if the amount of light is excessively reduced, the amount of light necessary for photographing cannot be obtained, making it difficult to recognize the measurement target droplet. Therefore, it is necessary to adjust the amount of light in order to focus on the distal end portion of the discharge needle 16 of the dispenser 18 and to obtain an image in which the edge portion of the contact point determination member can be confirmed.

In the configuration shown in FIG. 1, a method (configuration) for measuring a light amount range suitable for photographing is shown in FIG. As shown in the figure, the center point of the light source unit 20 and the center point of the camera unit 22 coincide (so that the optical axis of the imaging system of the camera unit 22 is positioned on the optical axis of the light source unit 20). The positions of the light source unit 20 and the camera unit 22 are adjusted, and measurement is performed at each of the measurement points P _{1 to} P ₃ on the straight line Y connecting the two points illustrated by broken lines in FIG.

Measurement point P ₁ is the lens position of the camera unit 22, the measurement point P ₂ is the center position of the XY stage 14, the measurement point P ₃ is the irradiation surface position of the light source unit. The photographed image is confirmed while changing the output value of the light source unit 20, and the range of the amount of light in which the influence of reflection is suppressed to some extent and the image can be obtained so that the contour can be visually recognized is measured.

  As an example of the light quantity condition, the light quantity range at the measurement point P1 is 100 lux or more and 700 lux or less, and the light quantity range at the measurement point P2 is 200 lux or more and 1500 lux or less. The light quantity range at the measurement point P3 is 900 lux or more and 20000 lux or less.

  A preferable light amount range at an arbitrary position on the substrate 12 can be obtained from the measurement results of the three points described above. Although correction may be necessary depending on the type of the substrate 12 and the surface of the surface 12A of the substrate 12, it can be applied to all substrates and surface treatments by actually measuring using the substrate 12 (surface treatment) to be used. it can.

[Explanation of boundary point discrimination member]
Next, conditions such as the shape and size of the boundary point determination member will be described in detail. 10-14 illustrate the boundary point determination member applicable to the contact angle measurement method of this example.

  FIG. 10A illustrates a solid boundary point discriminating member 90 in which the horizontal projection shape (planar shape of the imaging surface by the camera unit) has a trapezoidal shape (upper base> lower base). ) Shows a solid boundary point discriminating member 92 whose horizontal projection shape is a trapezoidal shape (upper base <lower bottom) obtained by vertically inverting the trapezoid of FIG. The boundary point discriminating members 90 and 92 shown in FIGS. 10A and 10B are provided with handling portions 91 and 93 for handling.

  FIG. 11A schematically shows an image in which the boundary point determination member 90 shown in FIG. 10A is placed on the substrate 12. As shown in FIG. 11A, a mirror image 90B can be seen in the reflection portion of the substrate 12 (the portion shown in FIG. 11A with a dot hatch), so that the actual surface 12A of the substrate 12 is recognized. It is possible. The same applies to the boundary point discriminating member 92 shown in FIG. 11B, and the actual surface 12 </ b> A of the substrate 12 can be recognized by seeing the mirror image 92 </ b> B in the reflection portion of the substrate 12.

  Further, a horizontal boundary shape discriminating member 94 having a horizontally projected shape as shown in FIG. 12A or a circular boundary having a horizontally projected shape as shown in FIG. 12B. The point discriminating member 96 can obtain the same effect.

  That is, the horizontal projection shape of the boundary point discriminating member is applied to a square (for example, a trapezoid or a parallelogram), a triangle, a pentagon or more polygon, a circle, a semicircle, an ellipse, etc. The In other words, the projection shape in the horizontal direction of the boundary point determination member may be a shape having a side (or tangent) that contacts the surface 12A of the substrate 12 at an angle of less than 90 ° or greater than 90 °.

  When a liquid is used for the boundary point discriminating member, a different type of liquid (having different physical properties) from the liquid droplet to be measured may be used. FIG. 13 shows a captured image when a liquid having a larger contact angle with respect to the substrate 12 than the droplet to be measured is used.

  FIG. 13 shows a photographed image 100 of a droplet to be measured using ink for an ink jet recording apparatus and a photographed image 102 of a boundary point determination member using pure water. As shown in the figure, the boundary surface 104 (boundary point) can be reliably recognized by using a liquid having a larger contact angle with respect to the substrate 12 than the liquid to be measured. Also, under such conditions, there is no restriction that the droplet amount of the boundary point determination member is sufficiently smaller than the droplet amount to be measured.

  In the example shown in FIG. 13, the ink drop amount is 2 μl (microliter), and the drop amount of the boundary point discriminating member (pure water) is 2 μl (microliter) as well as the ink drop amount. If the contact angle of the boundary point determination member with respect to the substrate 12 is 90 ° or more, the actual surface 12A of the substrate 12 can be determined.

  FIGS. 14 to 16 show configuration examples of dispensers when different types of liquid are used for the boundary point determination member. A dispenser 118 shown in FIG. 14 includes a measurement target droplet discharge needle 116A for dropping a measurement target droplet 110 and a boundary point determination member discharge needle 116B for dropping a boundary point determination member droplet 110. The target droplet discharge needle 116 </ b> A and the boundary point determination member discharge needle 116 </ b> B are connected by a connecting portion 117. FIG. 14 is a view as seen from the camera unit (see FIG. 1) side.

  According to such a structure, the distance between the measurement target droplet 110 and the boundary point determination member 112 can be fixed, and the captured image of the measurement target droplet 110 and the captured image of the boundary point determination member 112 within one screen. Can be stored in one screen.

  A dispenser 118 ′ shown in FIG. 15A is configured to include a boundary point determination member 92 (the columnar solid shown in FIG. 10B) instead of the boundary point determination member discharge needle 116 </ b> B. In this aspect, the measurement target droplet discharge needle 116A and the boundary point determination member 92 are configured to be movable up and down separately by driving (or manually), and the measurement target droplet discharge needle 116A alone is brought close to the substrate 12. Then, the droplet 110 to be measured can be dropped, and thereafter (or before that), the boundary point determination member 92 can be placed close to the substrate 12 alone and the boundary point determination member can be arranged.

  As shown in FIG. 15 (b), the shape of the tip of the boundary point determination member 92 may be a shape that spreads toward the tip (reverse taper shape).

  FIG. 16 (a) shows a dispenser 118 ″ according to still another aspect. In the aspect shown in the figure, the position (height) of the distal end portion of the measurement target droplet discharge needle 116A and the boundary point determination member That is, the position of the tip portion of the substrate 92 is displaced, that is, the distance between the substrate 12 and the tip portion of the measurement target droplet discharge needle 116A is larger than the distance between the substrate 12 and the tip portion of the boundary point determination member 92. It has become.

  The difference between the position of the tip of the measurement target droplet discharge needle 116A and the position of the tip of the boundary point discriminating member 92 indicates that the substrate 12, the measurement target droplet 110, and the measurement target liquid are displayed on the photographing screen of the camera unit. The tip of the droplet discharge needle 116A and the boundary point discriminating member are determined (see FIG. 16B). Note that, as shown in FIG. 16C, the shape of the tip of the boundary point determining member discharge needle 116B shown in FIG. 15B may be applied.

  Next, the contact angle measuring method described above will be described in the order of steps. Unless otherwise specified, reference numerals used in the following description are those used in FIG.

(Process 1: Light intensity adjustment)
The camera unit 22 is focused on the tip of the discharge needle 16 of the dispenser 18 to adjust the light amount of the light source unit 20.

(Process 2: Arrangement of contact point discrimination member)
The substrate 12 is placed on the XY stage 14, and a very small amount of liquid droplets of the same type as the liquid droplets to be measured serving as contact point recognition members are dropped. It is preferable that the amount of the small amount of droplets (contact point determination member) be at least an amount that does not contact the apparent substrate surface. However, if both edge portions of the image of the minute droplet can be identified, the minute droplet may contact the apparent substrate surface.

(Process 3: Drop of measurement target droplet)
The dropper dispenser 18 is filled with the solution, and the amount of droplets to be dropped is determined.

  After dropping the contact point recognition member, the substrate 12 is moved in parallel from the dropping position, and the measurement target droplet is dropped so as to be within the same photographing screen. In addition, it is also possible to replace the process 2 and the process 3.

(Process 4: Shooting)
The camera unit 22 is used to photograph the measurement target droplet and the contact point determination member.

(Process 5: contact point setting → contact angle calculation)
A contact point (a boundary surface between the substrate 12 and the measurement target droplet) is set from the image of the camera unit 22, and a contact angle is calculated.

  The photographing by the camera unit 22 was measured 1 second after the droplet to be measured landed on the substrate 12 (after the shape of the droplet after landing was stabilized). The measurement time may be set as appropriate depending on the type of droplet to be measured and the surface property of the substrate 12. For example, to measure the time-dependent change of the deposited droplet, you can shoot every 0.1 seconds or every 1 second, which can be changed according to the measurement purpose and the combination of droplet and substrate. It is.

  In the contact angle measuring system and method configured as described above, a contact point discriminating member for discriminating the boundary between the substrate surface and the liquid droplet to be measured is installed in the same plane as the liquid droplet to be measured, Since the droplet and the contact point discriminating member are photographed so as to be within the same screen and the boundary between the substrate and the droplet to be measured is judged based on the photographed image, the contact angle can be accurately and easily measured. .

  In this example, a mode in which a straight line is manually drawn on the end point of the contact point determination member is illustrated, but a program for automatically recognizing the actual substrate surface (automatically correcting the apparent substrate surface to the actual substrate surface) is built. This can be automated. That is, a program including each process of the method invention may be created, and the contact angle measurement program may be executed by the image processing device 26.

  In this example, the static contact angle is mainly described, but the present invention can also be applied to contact point identification at other dynamic contact angles. Further, the ink, pure water, and water repellent film described in this example do not limit the contents of the present invention.

  The present invention is suitable for evaluation of a recording medium on which ink is ejected from an ink jet recording apparatus, evaluation and inspection of a liquid repellent film on the ink ejection surface of an ink jet head, evaluation and inspection of a color filter used in a liquid crystal display, etc. ing.

  The contact angle measurement method and contact angle measurement system of the present invention have been described in detail above, but the present invention is not limited to the above examples, and various improvements and modifications can be made without departing from the scope of the present invention. Of course you can go.

<Appendix>
As will be understood from the description of the embodiments of the invention described in detail above, the present specification includes disclosure of various technical ideas including at least the invention described below.

  (Invention 1): Dropping means for dropping a droplet to be measured on the surface of a substrate; Arrangement means for disposing a boundary determining member for determining a boundary between the substrate and the droplet on the surface of the substrate; An imaging means for imaging the droplet and the boundary determination member from a horizontal direction or an oblique direction with respect to the substrate so that the droplet and the boundary determination member are within the same screen, and the boundary obtained by the imaging means Boundary determination means for determining the boundary between the substrate and the droplet from the image of the determination member; contact angle deriving means for determining a contact angle of the droplet with respect to the substrate at the boundary determined by the boundary determination means; A contact angle measuring system comprising:

  According to the present invention, the boundary discriminating member is disposed in the same plane as the measurement target droplet, and both are photographed so that the measurement target droplet and the boundary discriminating member are within the same screen, and the substrate is based on the photographed image. And the measurement target droplet are grasped, so that the boundary surface is not erroneously recognized. Therefore, it is possible to accurately measure the contact angle without using a highly functional image analysis program and without finely adjusting the light source according to the type of measurement sample or droplet.

  (Invention 2): In the contact angle measurement system according to Invention 1, the boundary determination means includes automatic recognition means for automatically recognizing the surface of the substrate from the image of the droplet obtained by the imaging means; Correction means for determining the boundary between the substrate and the droplet from the image of the boundary determination member obtained by the photographing means, and correcting the surface of the substrate recognized by the automatic recognition means based on the determination result; A contact angle measurement system characterized by including.

  According to this aspect, even when the surface of the substrate (the boundary surface between the substrate and the liquid droplet to be imaged) is automatically recognized from the captured image of the liquid droplet to be measured, the surface of the substrate that has been automatically recognized is detected by the boundary determination member. The contact angle can be accurately measured by correcting the boundary surface between the substrate grasped from the image and the droplet to be measured.

  (Invention 3): In the contact angle measurement system according to Invention 1 or 2, in the boundary determination member, a planar shape of a surface imaged by the imaging unit is less than 90 ° or 90 ° with respect to the surface of the substrate. A contact angle measuring system having a hypotenuse that forms an angle exceeding.

  According to this aspect, by making the boundary determination member symmetrical in a convex shape or a concave shape in the horizontal direction, the boundary surface between the substrate and the droplet to be measured can be easily grasped from the captured image of the boundary determination member. Can do.

  (Invention 4): The contact angle measurement system according to any one of Inventions 1 to 3, wherein the boundary determination member is the same type of liquid as the liquid droplet to be measured. system.

  According to this aspect, there is no damage to the substrate, and there is no need to separately provide a dropping means for the boundary determination member.

  (Invention 5): In the contact angle measurement system according to any one of Inventions 1 to 4, the boundary determination member is a liquid and has a liquid volume smaller than that of the droplet to be measured. Contact angle measurement system.

  According to this aspect, the entire shape of the captured image of the boundary determination member can be grasped, and the boundary surface between the substrate and the droplet to be measured can be grasped more accurately.

  (Invention 6): In the contact angle measurement system according to any one of Inventions 1 to 5, the boundary determination member is a liquid, and the contact angle with respect to the substrate is 90 ° or more. Angular measurement system.

  In this aspect, the arrangement means includes boundary determination member means for dropping the liquid as the boundary determination member onto the substrate.

  (Invention 7): In the contact angle measurement system according to any one of Inventions 1 to 5, the boundary determination member is a liquid, and the contact angle with respect to the substrate is 90 ° or more, and the liquid to be measured A contact angle measuring system having the same liquid volume as a droplet.

  According to this aspect, by using a liquid having a known contact angle as the boundary determination member, it is possible to make the dropping amount of the boundary determination member the same as the droplet to be measured.

  (Invention 8): In the contact angle measurement system according to any one of Inventions 1 to 3, the boundary determination member is a solid, and a planar shape of a surface imaged by the imaging means is a semicircle or a semicircle A contact angle measurement system including a circle, a triangle, a trapezoid, a parallelogram, and a polygon that is a pentagon or more.

  According to this aspect, the boundary determination member may be a solid.

  (Invention 9): A dropping step of dropping a droplet to be measured on the surface of the substrate; a disposing step of disposing a boundary determining member for determining a boundary between the substrate and the droplet on the surface of the substrate; An imaging step of imaging the droplet and the boundary determination member from a horizontal direction or an oblique direction with respect to the substrate so that the droplet and the boundary determination member are within the same screen, and the boundary obtained by the imaging step A boundary determination step for determining a boundary between the substrate and the droplet from an image of the determination member; a contact angle deriving step for obtaining a contact angle of the droplet with respect to the substrate at the boundary determined in the boundary determination step; A contact angle measuring method comprising:

  In the boundary determining step, the boundary determining unit automatically recognizes the surface of the substrate from the droplet image obtained in the photographing step, and the boundary determining member obtained by the photographing unit. And a correction step of determining a boundary between the substrate and the droplet from the image and correcting the surface of the substrate recognized by the automatic recognition step based on the determination result.

1 is an overall configuration diagram of a contact angle measurement system according to an embodiment of the present invention. The figure explaining the apparent surface in the photographed image The figure explaining the function of a contact point discrimination member Diagram explaining the setting of the contact point (boundary surface) The figure explaining the light quantity of a light source unit It shows a photographic image of the measuring point P ₁ in FIG. 5 It shows a photographic image of the measuring point P ₂ in FIG. 5 It shows a photographic image of the measuring point P ₃ in FIG. 5 Diagram explaining how to measure light The figure explaining the one aspect | mode of the contact point discrimination | determination member shown in FIG. The figure explaining the picked-up image of the contact point discrimination | determination member shown in FIG. The figure explaining the other aspect of the contact point discrimination | determination member shown in FIG. The figure explaining the further another aspect of the contact point discrimination | determination member shown in FIG. Configuration example of dispenser when using contact point discriminating member shown in FIG. 14 is a configuration example of another aspect of the configuration example of the dispenser shown in FIG. Configuration example of another aspect of the configuration example of the dispenser shown in FIG. Diagram explaining contact angle The figure explaining the contact angle measuring method concerning a prior art The figure explaining the measurement result in the contact angle measuring method shown in FIG. The figure explaining the measurement result in the contact angle measuring method shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Contact angle measuring system, 12 ... Board | substrate, 12A ... Surface, 18 ... Dispenser, 20 ... Light source unit, 22 ... Camera unit, 26 ... Image processing apparatus, 52, 90, 92, 94, 96, 102 ... Contact point discrimination Element

Claims (9)

Dropping means for dropping a droplet to be measured on the surface of the substrate;
Arranging means for arranging a boundary discriminating member for discriminating the boundary between the substrate and the droplet on the surface of the substrate;
Imaging means for photographing the droplet and the boundary determination member from a horizontal direction or an oblique direction with respect to the substrate so that the droplet and the boundary determination member are within the same screen;
Boundary determination means for determining the boundary between the substrate and the droplet from the image of the boundary determination member obtained by the photographing means;
Contact angle deriving means for obtaining a contact angle of the droplet with respect to the substrate at the boundary determined by the boundary determining means;
A contact angle measuring system comprising: The contact angle measurement system according to claim 1,
The boundary determination means includes automatic recognition means for automatically recognizing the surface of the substrate from the image of the droplet obtained by the photographing means,
Correction means for determining the boundary between the substrate and the droplet from the image of the boundary determination member obtained by the photographing means, and correcting the surface of the substrate recognized by the automatic recognition means based on the determination result;
A contact angle measurement system comprising: The contact angle measurement system according to claim 1 or 2,
The contact angle measuring system, wherein the boundary determining member has a hypotenuse in which a planar shape of a surface imaged by the imaging means forms an angle of less than 90 ° or more than 90 ° with respect to the surface of the substrate. The contact angle measuring system according to any one of claims 1 to 3,
The contact angle measurement system, wherein the boundary determination member is the same type of liquid as the droplet to be measured. The contact angle measurement system according to any one of claims 1 to 4,
The contact angle measurement system according to claim 1, wherein the boundary determination member is a liquid and has a smaller liquid volume than the liquid droplet to be measured. The contact angle measuring system according to any one of claims 1 to 5,
The boundary determination member is a liquid, and a contact angle with respect to the substrate is 90 ° or more. The contact angle measuring system according to any one of claims 1 to 5,
The contact angle measuring system, wherein the boundary determining member is a liquid, has a contact angle with respect to the substrate of 90 ° or more, and has the same liquid amount as the liquid droplet to be measured. The contact angle measurement system according to any one of claims 1 to 3,
The boundary discriminating member is solid, and the plane shape of the surface photographed by the photographing means includes a semicircle, a semi-ellipse, a triangle, a trapezoid, a parallelogram, and a pentagon or more polygon. Angular measurement system. A dropping step of dropping a droplet to be measured on the surface of the substrate;
An arrangement step of arranging a boundary discriminating member for discriminating a boundary between the substrate and the droplet on the surface of the substrate;
An imaging step of photographing the droplet and the boundary determination member from a horizontal direction or an oblique direction with respect to the substrate so that the droplet and the boundary determination member are within the same screen;
A boundary determination step for determining a boundary between the substrate and the droplet from the image of the boundary determination member obtained by the photographing step;
A contact angle deriving step for obtaining a contact angle of the droplet with respect to the substrate at the boundary determined in the boundary determining step;
A contact angle measuring method comprising:

Images