JP4049780B2 - Ink droplet measurement method after landing and ink droplet measurement device after landing - Google Patents

Description

The present invention relates to a method and an apparatus for measuring a diameter or width after landing of an ink droplet, and more particularly, to a transparent or translucent object on a transparent or translucent object having non-ink-absorbing properties. The present invention relates to a technique for measuring the diameter or width of an ink droplet when the ink droplet has landed.

  In recent years, in addition to performing printing with an ink jet printer on a substrate made of paper, cloth, resin, ceramic, or the like, when forming an alignment film on a transparent glass substrate in a liquid crystal display device or the like, Inkjet printers have come to be used even when a color filter is applied on a transparent glass substrate in a display. More specifically, in the case of a liquid crystal display device, a transparent PI ink (transparent polyimide ink) or a transparent UV ink, which is a material of the alignment film, is applied by being discharged onto a glass substrate (for example, Patent Document 1). In the case of an organic EL display device, a transparent UV ink, which is a coating material, is ejected and applied onto a glass substrate.

  By the way, when ink is ejected onto an object to be coated that does not absorb ink (ink non-absorbability) like the above glass substrate using an ink jet printer, the spread of ink droplets after landing If the property is not sufficiently grasped, it may cause a situation such as the ink droplets that have landed do not fuse properly, and it becomes difficult to form a high-quality film having a uniform film thickness on the object to be coated. Therefore, when forming a film by actually ejecting ink onto a coated object having non-ink-absorbing properties, the spread of ink droplets after landing on the coated object is accurately grasped in advance. It is very important to keep it.

  In view of such a situation, conventionally, as a method of grasping the spread of ink droplets after landing on an object to be coated, pure water or ink itself is dropped on the surface of the object to be coated, and the existing contact angle As shown in FIG. 8, the contact angle “a” formed between the surface of the peripheral edge portion 13 a of the ink droplet 13 and the surface 12 a of the coating object 12 is measured using a meter. As the contact angle a decreases with an acute angle, the hydrophilicity of the surface of the object to be coated is improved and the spreadability of the ink droplets is improved, which is advantageous in forming a film having a uniform thickness. It had been. However, the spreadability of the ink droplets on the coated object is not only different depending on the characteristics of the ink and the surface state of the coated object, but also other factors such as the size of the ejected ink droplet and the ejection speed Also depends on. Considering such matters, it can be concluded that the above-mentioned conventional method cannot properly grasp the spreading property of the ink droplet.

JP 2001-42330 A

  In order to avoid the above-mentioned conventional problems, the present inventors landed ink droplets of ink actually used on an object to be coated using an ink jet printer that is actually used. The inventors have come up with a method for measuring the diameter of ink droplets. According to this method, the ink droplet spreads on the coating material while taking into account all the factors such as the characteristics of the ink, the surface condition of the coating material, the size of the ejected ink droplet, and the ejection speed of the ink droplet. Therefore, it can be expected to obtain a high-quality film having a uniform thickness.

  However, even if such a method is used, if the ink is transparent or translucent (hereinafter, “transparent or translucent” is also simply referred to as “transparent etc.”), the ink droplet is not visible or difficult to see. In addition, if it is difficult or impossible to measure the diameter of the ink droplets and the coated object is also transparent, the ink droplets are more difficult to see, resulting in further hindrance to the measurement of the ink droplet diameter.

  Such a problem is caused when a transparent PI ink or UV ink, which is a material of the alignment film, is ejected onto a transparent glass substrate in the liquid crystal display device described above, or a transparent glass substrate in an organic EL display. This is particularly noticeable when a transparent UV ink is ejected on the top, but in addition to this, on a resin substrate such as a transparent substrate or a transparent substrate for producing a semiconductor element, the same as above or other transparent The same can occur when ejecting ink.

The present invention has been made in view of the above circumstances, and appropriately measures the diameter or width of transparent ink droplets on an object to be coated such as transparent, and has a uniform thickness on the object to be coated. It is a technical subject to form the film.

The method according to the present invention, which was created to solve the above technical problem, is to apply transparent or translucent ink to a transparent or translucent object to be ink non-absorbed by an ink droplet discharge device. A post- landing ink drop measurement method for measuring the diameter or width of an ink drop after being ejected as a drop and landing on the object to be coated, wherein the ink drop is placed on the object to be coated. By ejecting the ink droplets so as to overlap each other, the amount of light reflected or refracted at the peripheral portion of the ink droplet group formed by landing on it is ejected once and landed on the peripheral portion of the ink droplet landed. More specifically, the diameter or width of the peripheral portion of the ink droplet group is measured .

According to such a post-landing ink droplet measurement method, the peripheral portion of an ink droplet group (an overlapping collection of ink droplets) formed by ejecting ink droplets so as to overlap each other and landing on an object to be coated Compared with the peripheral part of the ink droplet that is ejected only once and landed on the coated object, the degree of protrusion from the surface of the coated object increases, and the amount of light reflected or refracted at the peripheral part However, the amount of light is appropriately larger than the amount of light reflected or refracted at other parts (flat central part or the like). Thus, the image pickup means such as a visual or CCD camera, can be clearly visually recognize the peripheral portion of the ink droplet group, for example by measuring the diameter and width of the ink droplet group, the spread of the ink (the Since it is possible to accurately grasp the size of the ink droplet or ink droplet group after landing on the coated material, the nature of the size and width (hereinafter the same)) , the coated object A high-quality film having a uniform thickness can be formed thereon.

  More specifically, since the surface of the above-described coated object is subjected to a cleaning action in a cleaning process that is a pre-process of the ink discharge process, the surface quality of each coated object varies, and thus the surface of an inkjet printer or the like. Even if the ink droplet ejection device and the ink ejection conditions are constant, the spreadability of the ink droplets is not uniformly determined. Therefore, in order to ascertain whether the surface state of the object to be coated, the ink droplet ejection device and the ink ejection conditions are appropriate, the ink droplets are actually ejected onto the object as in the present invention. It is preferable to measure the spreadability. Then, after confirming that the spreadability is appropriate, if a film is continuously formed by ejecting ink, a product in which a high-quality film is formed on an object to be coated can be mass-produced. On the other hand, if the film formation by continuous ink ejection is performed without confirming whether or not the spreading property of the ink droplets on the coated object is appropriate as described above, a large number of defective products are produced. This causes a problem that the product yield is significantly reduced. In consideration of such matters, according to the present invention, even when transparent ink or the like is ejected onto an object to be coated such as transparent, the spreadability of ink droplets on the object to be coated Therefore, it is possible to effectively avoid the significant decrease in the product yield as described above.

  In the above method, when ejecting ink droplets so as to overlap a plurality of times, it is preferable that only a part of each ink droplet is ejected.

In this way, when the subsequent ink droplet is ejected after the preceding ink droplet has landed on the coating object, a part of the subsequent ink droplet lands on the surface of the preceding ink droplet. However, other portions land on the surface of the object to be coated. As a result, when all of the ink droplets overlap, that is, when the ink droplets landed on the surface of the object to be coated in advance so that all of the subsequent ink droplets overlap, This makes it difficult to measure the spreadability of ink droplets due to the above.

Further, in the above method, the landing side or back side thereof an ink droplet in the object to be coated, the imaging means for capturing an image of the periphery of the ink droplet group placement to Rukoto are preferred.

  In this way, the peripheral portion of the ink droplet group is captured as an image by the imaging means, which is advantageous in measuring the spread diameter or spread width of the ink droplet. For example, the measurement is automatically performed. It is also possible. Further, since the object to be coated is transparent or the like, the image pickup means can be arranged on either the ink droplet landing side or the back side of the object to be coated, which makes it difficult to cause a problem in layout. .

  In the above invention, the object to be coated is a glass substrate for a liquid crystal display device or an organic EL display, and the ink is an alignment film material for a liquid crystal display device or a coating material for an organic EL display device. For example, it helps to improve the quality of liquid crystal display devices and organic EL display devices. Examples of the alignment film material include transparent PI ink (transparent polyimide ink) and transparent UV ink, and examples of the coating material include transparent UV ink. .

  Furthermore, in the above invention, if the ink droplet ejection device is an ink jet printer, it is possible to effectively and surely enjoy the above-described effects.

On the other hand, an apparatus according to the present invention, which was created to solve the above technical problem, is a transparent or semi-transparent ink on a transparent or semi-transparent coated object having ink non-absorbability by an ink droplet ejection device. Is a post- landing ink droplet measuring device that measures the diameter or width of the ink droplet after the ink droplet has landed on the object to be coated. The peripheral portion of the ink droplet formed by ejecting and landing the amount of light reflected or refracted by the peripheral portion of the ink droplet group formed by discharging the droplets so as to overlap each other multiple times. The peripheral portion of the ink droplet group can be clearly seen, and the diameter or width of the peripheral portion is measured .

According to such a post-landing ink droplet measuring device, the corresponding component in the above-described method is provided, so that the spread of the ink is accurately grasped for the reason already described, and then the object to be coated A high-quality film having a uniform thickness can be formed thereon, and a significant reduction in product yield can be avoided.

  In this case, as the ink described above, for example, when a film material having a viscosity of 5 to 16 cp and a surface tension of 30 to 40 dyn / cm is used, the various effects described above are remarkably obtained. be able to.

  As described above, according to the present invention, the peripheral portion of the ink droplet group formed by ejecting the ink droplets so as to overlap with each other and landing on the subject is ejected only once and the subject is applied. Compared with the peripheral part of the ink droplet landed on the top, the amount of reflected or refracted light is more accurately than other parts, so the peripheral part of the ink droplet group can be clearly seen, and the ink Therefore, it is possible to accurately grasp the spreadability of the film, whereby a high-quality film having a uniform thickness can be formed on the object to be coated. Furthermore, since it is possible to continuously form a film by ejecting ink after confirming that ink droplet spread is appropriate, a high-quality product in which a high-quality film is formed on an object to be coated Can be mass-produced and the product yield can be improved.

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1A shows an inkjet print head 1 that is a component of a post-landing ink droplet measuring device according to an embodiment of the present invention, and a transparent line drawn as a solid line as an object to be coated before ink droplets are ejected. FIG. 1B is a schematic plan view showing the glass substrate 2 and the glass substrate 2 drawn by dotted lines after ink droplets (ink droplet group 3) are ejected, and FIG. It is a schematic side view showing each component 1,2. FIG. 2 is a schematic side view showing an arrangement state of the inspection camera 4 and the plurality of lights 5 and 6 which are components of the post-landing ink droplet measuring apparatus according to the embodiment of the present invention.

In this embodiment, as shown in FIGS. 1 (a) and 1 (b), when the glass substrate 2 moves in the direction of the arrow below the inkjet print head 1 held in place, the surface of the glass substrate 2 is moved. When ink droplets are ejected and the glass substrate 2 moves to the position indicated by the dotted line, an ink droplet group (a collection of ink droplets formed by overlapping ink droplets) 3 that has landed on the surface of the glass substrate 2 Spreadability is to be measured .

As shown in FIG. 2, the configuration of the inspection unit 7 that measures the spreadability of the ink droplet group 3 is the landing side of the ink droplet group 3 on the glass substrate 2, specifically, the ink droplet group 3 on the glass substrate 2. One inspection camera 4 composed of a CCD camera disposed directly above and directed downward, and light radiated symmetrically from above obliquely to the ink droplet group 3 disposed on the landing side of the ink droplet group 3 on the glass substrate 2 And two illuminations 6 that are arranged behind the landing side of the ink droplet group 3 on the glass substrate 2 and irradiate light symmetrically from below the ink droplet group 3. .

  In this case, the ink droplet group 3 on the glass substrate 2 is formed by discharging the ink droplets at the same position over a plurality of times, and as shown in FIG. The peripheral edge portion 3a has an extremely curved shape as compared with the central portion 3b that is gently curved. In other words, the contact angle a of the peripheral edge 3a of the ink droplet group 3 with respect to the surface of the glass substrate 2 is far greater than the contact angle a of the ink droplet 13 ejected only once shown in FIG. growing. Therefore, when the ink droplet group 3 is irradiated with light by the illuminations 5 and 6 and the image is captured by the inspection camera 4, the circular central portion 3b shown in FIG. 4 is relatively flat. However, the ring-shaped peripheral edge 3a shown in the figure can be visually recognized as being in a white floating state because the amount of reflected or refracted light is relatively large. Therefore, if the diameter D of the ink droplet group 3 is measured, the spreadability of the ink glass substrate 2 actually used in the inkjet printer can be grasped in advance.

  On the other hand, depending on the characteristics of the ink used, if the ink droplets were ejected to the same position a plurality of times as described above, when the succeeding ink droplets land on the preceding ink droplets, When the perimeter of the ink droplet group does not curve to the extent described above, and the perimeter does not rise to a white state, and the inspection camera cannot grasp the spread of the ink. There is. In such a case, as shown in FIGS. 5A and 5B, only a part of the plurality of ink droplets 13 ejected over a plurality of times overlaps, that is, the landing of each ink droplet 13. By discharging while moving in one direction so that the positions partially overlap, an image formed of the elliptical transparent central portion 3b shown in FIG. 6 and the elliptical ring-shaped peripheral portion 3a floating in white is obtained as an inspection camera. Can be caught with. Then, if the width S of the ink droplet group 3 is measured from the image shown in FIG. 6, the spreadability of the ink glass substrate 2 actually used in this ink jet printer can be grasped in advance.

  FIG. 7 shows another example of the inspection unit 7, and the illuminations 5 and 6 are arranged in the same manner as described above, and the inspection camera 4 moves the ink droplet group 3 on the glass substrate 2. The rear side of the landing side, specifically, the ink droplet group 3 on the glass substrate 2 is arranged directly below and arranged to face upward. Even in such an arrangement state of the illuminations 5 and 6 and the inspection camera 4, the peripheral edge portion 3 a of the ink droplet group 3 can be captured as a white floating state in the same manner as described above, and the glass substrate 2. It is possible to accurately grasp in advance the spreadability of the ink.

In addition, the post-landing ink droplet measuring apparatus according to the above-described embodiment is a case where a transparent PI ink or UV ink which is a material of an alignment film is ejected onto a transparent glass substrate in a liquid crystal display device or the like, or an organic EL It is particularly useful when discharging UV ink such as transparency on a glass substrate such as transparency in a display, but in addition to this, on a resin substrate such as transparency or on a transparent substrate such as a semiconductor element manufacturing action, The same applies to the case where similar or other transparent ink is ejected.

FIG. 1 (a) is a schematic plan view showing an ink jet print head which is a component of a post-landing ink droplet measuring apparatus according to an embodiment of the present invention and its periphery, and FIG. 1 (b) is a schematic side view thereof. is there. It is a schematic side view which shows the structure of the test | inspection part of the ink droplet measuring apparatus after landing which concerns on embodiment of this invention. It is a schematic side view which shows the ink droplet group on the to-be-coated object which is a target object by the ink droplet measuring apparatus after landing which concerns on embodiment of this invention. It is a schematic plan view which shows the shape of the ink droplet group which is a target object by the ink droplet measuring apparatus after landing which concerns on embodiment of this invention. FIG. 5A is a schematic plan view showing another example of an ink droplet group on an object to be coated by the post-landing ink droplet measurement device according to the embodiment of the present invention, and FIG. It is the schematic side view. It is a schematic plan view which shows the shape of the said other example of the ink droplet group which is a target object by the ink droplet measuring apparatus after landing which concerns on embodiment of this invention. It is a schematic side view which shows the other example of the test | inspection part of the ink drop measuring apparatus after a landing which concerns on embodiment of this invention. It is a schematic side view which shows the state of the ink drop on the to-be-coated object at the time of discharging only once.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet print head 2 Glass substrate 3 Ink droplet group 3a Peripheral part of ink droplet group 4 Inspection camera (imaging means)
13 Ink droplet (single ink droplet)

Claims (6)

On the object to be coated in transparent or semi-transparent with an ink non-absorbent, transparent or semi-transparent by the ink droplet ejection device inks ejected as an ink droplet, after the ink droplets have landed on the object to be coated A method of measuring an ink droplet after landing for measuring the diameter or width of the ink droplet ,
On the object to be coated, by ejecting so as to overlap over the ink droplets to a plurality of times, the amount of light they reflect or refract at the periphery of the ink droplet group consisting landed, and the discharge only once The landing is characterized in that the diameter or width of the peripheral portion of the ink droplet group is measured after making the peripheral portion of the ink droplet group clearly visible after increasing the number of the peripheral portion of the landed ink droplet. Post ink drop measurement method. 2. The post-landing ink according to claim 1, wherein when ejecting the ink droplets so as to overlap a plurality of times, the ink droplets are ejected such that only a part of each ink droplet overlaps. Drop measurement method. The landing side or back side thereof an ink droplet in the object to be coated, the landing after the ink droplets according to claim 1 or 2, characterized in the kites are arranged with imaging means for capturing an image of the periphery of the ink droplet group Measuring method. The coated object is a glass substrate for a liquid crystal display device or an organic EL display, and the ink is an alignment film material for a liquid crystal display device or a coating material for an organic EL display device. The method of measuring ink droplets after landing according to any one of claims 1 to 3. The post-landing ink droplet measurement method according to claim 1, wherein the ink droplet ejection device is an ink jet printer. On the object to be coated in transparent or semi-transparent with an ink non-absorbent, transparent or semi-transparent by the ink droplet ejection device inks ejected as an ink droplet, after the ink droplets have landed on the object to be coated A post-landing ink droplet measuring device for measuring the diameter or width of the ink droplet ,
On the object to be coated, by ejecting to overlap across the ink droplets to a plurality of times, the amount of light they reflect or refract at the periphery of the ink droplet group consisting landed, and the discharge only once The configuration is such that the diameter or width of the peripheral portion of the ink droplet group is measured after making the peripheral portion of the ink droplet group clearly visible, more than that of the peripheral portion of the landed ink droplet. Ink droplet measurement device after landing .

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