JP2009106818A - Liquid droplet discharge level detection method/detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet discharge level detection method which enables the rapid discharge operation of a liquid droplet while determining the liquid droplet discharge level through detecting the total liquid droplets to be discharged in a real time mode, and also, a liquid droplet discharge level detector. <P>SOLUTION: This liquid droplet discharge level detection method is designed to discharge a liquid agent to the surface of a target object after preliminary discharge, and comprises the following operating steps: (1) the liquid droplet amount calculation step to calculate the amount of the liquid droplet to be discharged during the preliminary discharge, (2) the liquid droplet counting step to count the number of liquid droplets to be discharged to the target object, and (3) the liquid droplet discharge level calculation step to make the value obtained by multiplying the liquid droplet amount calculated by the liquid droplet amount calculation step with the number of the liquid droplets counted by the liquid droplet counting step, the liquid droplet discharge level to the target object. Thus it is possible to correctly control the discharge level from the discharged liquid droplets without adversely affecting a rapid operation, and precisely applying a functional liquid agent to the target object in the form of microdosage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a droplet discharge amount detection method and a droplet discharge amount detection for detecting a droplet discharge amount when a liquid agent is applied to an object from a nozzle by an ink jet type droplet discharge device that discharges a functional liquid as a liquid agent. It relates to the device.

  In the field of manufacturing liquid crystal display devices and the like, liquid droplet ejection devices that apply a functional liquid to an object using an inkjet method have begun to be introduced. The reason for introducing this droplet discharge device is that a liquid agent can be applied in a small amount with high accuracy by using an ink jet method. Therefore, when manufacturing a product by applying it with a droplet discharge device, it is important to apply the product while keeping the application amount highly accurate. For this purpose, it is desirable to accurately measure the coating amount by the droplet discharge device and confirm that the coating amount is maintained with high accuracy.

  As a method for measuring the application amount of the droplet discharge device, a method of measuring the application amount of the application object after application can be considered. However, since the amount applied by the ink jet method is very small and the liquid agent is dried after application, there is a disadvantage that the application amount cannot be measured accurately after application. Rather than the method of measuring after application having such drawbacks, there is a method of measuring the droplets discharged from the discharge head of the droplet discharge device that is supplying the liquid agent to the product in real time to obtain the application amount of the object. The amount of discharged droplets can be detected more accurately.

As a measurement method for measuring the ejected droplets in real time, as shown in FIG. 14, the droplet 52 ejected from the nozzle of the ejection head 51 is imaged by a high-speed camera 53 and ejected from the captured image. Patent Document 1 discloses a method of obtaining the coating amount by calculating the amount of all droplets 52 and integrating all the droplet amounts.
JP 2005-40690 A

  However, when the conventional droplet discharge amount detection method disclosed in Patent Document 1 is used, the amount of all discharged droplets 52 is calculated while performing image processing of a huge amount of image data. Since the integrated value is calculated, the calculation time becomes long when many droplets 52 are ejected. Therefore, even if a high-speed discharge operation is performed, it is actually difficult to measure the coating amount in real time while performing the high-speed discharge operation, and as a result, the high-speed discharge operation cannot be performed.

  The present invention solves the problems of the above-described conventional droplet discharge amount detection method, and is capable of performing a high-speed discharge operation while detecting the droplet discharge amount by detecting all the droplets discharged in real time. An object of the present invention is to provide an amount detection method and a droplet discharge amount detection device.

  In order to solve the above-described conventional problems, a droplet discharge amount detection method of the present invention is a droplet discharge amount detection method for discharging a liquid agent onto the surface of an object after preliminary discharge. A droplet amount calculating step for calculating an amount of discharged droplets, a droplet counting step for counting the number of droplets discharged to the object, and a droplet amount calculated in the droplet amount calculating step A droplet discharge amount calculating step in which a value obtained by multiplying the number of droplets counted in the droplet counting step is a droplet discharge amount discharged onto the object.

  Further, the droplet discharge amount detection device of the present invention includes a discharge head that discharges a liquid agent onto the surface of an object, a discharge device that outputs a driving pulse for discharging the liquid agent to the discharge head, and the discharge head. A light source for irradiating the discharged droplets with light, an imaging device for imaging the discharged droplets, a droplet detection device for detecting the discharged droplets, and the number of the detected droplets. A counting device for counting, an image processing device for calculating the volume of the droplet from the image of the droplet obtained by the imaging device, and the number of droplets counted by the counting device calculated by the image processing device. And a control device that sets a multiplication amount obtained by multiplying the volume of the droplets to a droplet discharge amount applied to the object from the discharge device.

  According to the droplet discharge amount detection method and the droplet discharge amount detection device of the present invention, the value obtained by multiplying the amount of droplets discharged at the time of discharge and the counted number of droplets is used as the droplet discharge amount. The ejection amount can be accurately controlled from the ejection droplets without impairing the high-speed operation, and the functional liquid agent can be applied to the object in a minute amount with high accuracy.

Embodiments of a droplet discharge amount detection method and a droplet discharge amount detection apparatus according to the present invention will be described below in detail with reference to the drawings.
(Embodiment 1)
FIG. 1 is a diagram showing a configuration of a droplet discharge amount detection device used in a droplet discharge amount detection method according to a first embodiment of the present invention, and FIG. 2 shows a detector of the droplet discharge amount detection device. FIG.

  As shown in FIG. 1, the droplet discharge amount detection device used in the droplet discharge amount detection method of the present invention is a discharge for discharging a liquid agent (droplet 9) onto the surface of an object 10 that discharges a droplet 9. A head 1, a discharge device 5 for outputting a driving pulse for discharging a liquid agent to the discharge head 1, a light source 4 for irradiating light onto a droplet 9 discharged from the discharge head 1, and a discharge. An imaging device 2 for acquiring the droplets 9 to be detected, a detector 3 as a droplet detection device for detecting the discharged droplets 9, and for counting the number of the detected droplets 9 The image processing device 7 for calculating the volume of the droplet 9 from the image of the droplet 9 acquired by the counting device 6 and the imaging device 2, and the image processing device 7 calculates the number of droplets counted by the counting device 6. The droplet discharge which applies the multiplication amount which multiplied the volume of the formed droplet 9 to the target object 10 from the discharge device 5 And a control device 8 for the amount.

  In FIG. 1, the droplet 9 ejected from the ejection head 1 is applied onto an object 10 disposed below the ejection head 1. The discharge head 1 includes a delicate nozzle 12 and a piezo element (not shown) that is an energy generation unit that generates liquid droplet formation energy provided in a liquid path and a part of the liquid path. The droplet 9 is ejected from the nozzle 12 by operating the piezo element by an electrical signal that is sometimes output. The liquid agent tank 11 is connected to the ejection head 1 and supplies the liquid agent to the ejection head 1.

  The discharge device 5 is connected to the control device 8. In the case of discharging the liquid agent, a discharge signal is sent from the control device 8 to the discharge device 5, and this discharge signal is converted into an electric signal for operating the discharge head 1 by the discharge device 5, and the liquid is discharged from the nozzle 12 of the discharge head 1. Drop 9 is discharged. A light source 4 using LEDs having a visible wavelength of 400 nm to 650 nm is connected to the ejection device 5, and this light source 4 is disposed below the nozzle 12 of the ejection head 1. The ejection device 5 synchronizes with the electrical discharge signal for operating the ejection head 1, and outputs a signal having a pulse width (0.5 μs to 20 μs) at a predetermined time from the electrical signal for operating the ejection head 1. And the light source 4 is pulse-lit.

  The imaging device 2 can obtain an image of one droplet 9 in the imaging range by capturing an image of the droplet 9 illuminated by pulse lighting of the light source 4 using an imaging element such as a CCD. It is configured.

  The image processing device 7 is connected to the imaging device 2 and the control device 8, synchronizes the imaging start signal sent from the control device 8 and the ejection signal sent to the ejection device 5, and is pulsed by the light source 4. An image of the illuminated droplet 9 is acquired. The image of the droplet 9 is binarized to obtain the area and diameter of the droplet 9, and the area and volume of the droplet 9 are calculated assuming that the droplet 9 is a sphere.

  The detector 3 is disposed below the nozzle 12 of the ejection head 1 at a location where the droplet 9 passes on the optical axis of the laser light 15 (see FIG. 2) generated from the light projecting unit 13. Specifically, the detector 3 is preferably arranged at a location rotated 90 degrees around the droplet 9 from the imaging device 2 above the imaging range of the imaging device 2. This is to prevent the laser light 15 of the detector 3 from being reflected by the droplet 9 ejected from the ejection head 1 and affecting the image of the imaging device 2 during imaging by the imaging device 2. .

  The configuration of the detector 3 is shown in FIG. The detector 3 includes a light projecting unit 13 and a light receiving unit 14, and the light projecting unit 13 uses a laser having a wavelength of 400 nm to 700 nm, and emits a laser beam 15 as parallel light toward the light receiving unit 14. The light receiving unit 14 includes a light receiving element using a photodiode, and the light receiving surface of the light receiving unit 14 includes a slit 16a having a horizontal direction of 0.5 to 1.5 mm and a vertical direction of 0.1 to 0.5 mm. 16 is attached. The slit component 16 is attached in close contact with the light receiving surface of the light receiving unit 14 with a thickness of about 1 to 10 mm. This is because the light from the light source 4 enters the light receiving unit 14 when the light source 4 is turned on, so that the measurement is not adversely affected. In the present embodiment, the slit width of the slit 16a is 1 mm in the horizontal direction × 0.3 mm in the vertical direction, and the thickness is 2.3 mm.

  The reason why the slit component 16 is attached to the light receiving unit 14 is that when the droplets are ejected from the ejection nozzle 1, the number of ejection signals and the number of droplets are counted to be the same. If there is no slit 16a, if the diameter of the laser beam 15 is large, a plurality of droplets 9 pass through the laser beam 15. This is because the next droplet 9 passes through the laser beam 15 before one droplet 9 finishes passing through the laser beam 15. Since the change in the amount of light of the two droplets 9 cannot be measured, it cannot be accurately counted. Therefore, the slit 16a is necessary. Since the laser light 15 is parallel light, if the slit 16a (slit component 16) is attached to the light receiving portion 14, the diameter of the laser light 15 entering the light receiving element can be determined. With the slit 16a, the length in the vertical direction can be determined so that the light receiving unit 14 does not have a plurality of droplets 9 for detecting a change in the amount of light, whereby the droplets 9 can be accurately counted.

  In this way, when the droplet 9 passes through the optical axis of the laser beam 15, the optical axis is blocked by the droplet 9, the amount of light incident on the light receiving unit 14 decreases, and the output signal of the photodiode changes. This output signal is input to the counting device 6.

  The counting device 6 counts the number of droplets from the analog signal of the light receiving unit 14 of the detector 3. The droplet counting method of the counting device 6 is performed by inputting an analog signal corresponding to the amount of received light from the light receiving element of the light receiving unit 14 to the counting device 6 by the laser beam 15. The input analog signal is compared with a threshold value by an analog comparator or the like, converted into a digital value, counted, and output to the control device 8.

  The configuration of the counting device 6 is shown in FIG. The counting device 6 includes a counter 19a having a counter that operates at a first threshold value 18a and a counter 19b that operates at a second threshold value 18b with respect to the output signal 17 from the light receiving unit 14. Here, the reason for counting with the two threshold values 18a and 18b is to detect an abnormal discharge of the droplet 9. The results counted by the respective counters 19a and 19b are sent to the control device 8.

  The analog signal of the light receiving unit 14 varies depending on the size of the discharged droplet 9. Therefore, by examining the difference in the analog signal of the light receiving unit 14, when the droplet diameter becomes smaller than in the case of normal ejection due to the adhesion of dust or bubbles generated inside the liquid path, the satellite (main droplet) In this case, it is possible to detect abnormality of the droplet 9 when the droplet diameter is smaller than that in the case of normal ejection such as non-ejection. The detection of abnormal droplets in the first embodiment is intended to detect that the droplet 9 is smaller than a normal droplet. For this reason, processing is performed with two threshold values 18a and 18b so that a droplet smaller than a normal droplet can be detected. In the present embodiment, two threshold values are set (first threshold value 18a> second threshold value 18b), and in this case, as will be described later, the advantage of being able to accurately detect an abnormality with a relatively small number of threshold values is provided. However, the present invention is not limited to this, and the abnormality processing may be performed with one threshold or three or more thresholds.

  Next, the abnormal droplet detection method will be described in more detail. FIG. 4A shows the droplet 9 in normal ejection. One droplet 9 has a spherical shape. FIG. 4B shows the case of abnormal ejection. Originally, one droplet 9 is broken into two, and is divided into satellites 9a and droplets 9b. FIG. 4C also shows the case of ejection abnormality. Due to the bubbles generated inside the liquid path, the droplet 9c discharged from the head is smaller than the normal droplet 9. FIGS. 5A, 5B, and 5C show analog signals of the light receiving unit 14 in the detector 3 in the cases shown in FIGS. 4A, 4B, and 4C, respectively. In the case shown in FIG. 5A, since the droplet 9 has a normal size, the analog signal decreases only once and crosses both the first threshold value 18a and the second threshold value 18b. In the case shown in FIG. 5B, since the satellite 9a has come out and two droplets 9a and 9b have been formed, the analog signal has been lowered twice, and the threshold values crossing each other are different (details). Is crossing both the first threshold value 18a and the second threshold value 18b in the main droplet 9a, but only the first threshold value 18a is crossed in the satellite 9a). In the case shown in FIG. 5C, since the droplet 9c itself is small, the analog signal decreases only once, but does not cross the second threshold value 18b.

  Accordingly, by detecting the values of the counter 19a having a counter that operates at the first threshold value 18a and the counter 19b that operates at the second threshold value 18b, it is possible to detect an abnormality in the discharge amount. That is, when the analog signal 17 from the light receiving unit 14 in the case illustrated in FIG. 5A is input, the analog signal 17 is set to a value lower than the values of the first threshold value 18a and the second threshold value 18b in one place. Therefore, the count values of the counter 19a and the counter 19b are the same and can be determined to be normal. On the other hand, when the analog signal 17 from the light receiving unit 14 in the case shown in FIG. 5B is input, the analog signal 17 is detected at two locations below the first threshold value 18a. The result differs from the value of the counter 19b, and it can be determined that there is an abnormality. In addition, when the analog signal 17 from the light receiving unit 14 in the case illustrated in FIG. 5C is input, the analog signal 17 detects a value lower than the threshold 18a with respect to the first threshold 18a. Since the second threshold value 18b has no value lower than the threshold value 18b, the counter 19b does not count even though the counter 19a counts, so that the counter value is different and it can be determined that there is an abnormality.

  6 shows a meniscus state of the nozzle 12 of the discharge head 1 during continuous discharge (when the liquid agent in the nozzle 12 comes into contact with the atmosphere, the curve generated by the magnitude relationship between the adhesion force acting between them and the cohesive force between the liquid molecules. It is the figure which showed the liquid surface state which carried out. By setting the optimal shape of the meniscus 20 in the nozzle 12 at the time of non-ejection to a state close to or the same as the shape of the meniscus 20 at the time of continuous ejection, the same amount of liquid droplets as that at the time of continuous ejection from the first droplet of ejection Is obtained. Therefore, the liquid agent tank that supplies the liquid agent to the discharge head 1 so that the meniscus state 20 when the discharge head 1 is not discharged is close to or the same as the shape of the meniscus 20 during continuous discharge shown in FIG. 11 is controlled to control the meniscus 20.

  FIG. 8 is a flowchart of the droplet discharge amount detection method according to the first embodiment. Steps S <b> 1 to S <b> 4 are preliminary ejection steps for calculating the droplet amount, and one droplet 9 is ejected from the ejection head 1. Steps S <b> 5 to S <b> 9 are normal discharge processes in which discharge is continuously performed at a cycle of 500 Hz to 5 kHz, and the droplets 9 are discharged onto the object 10 at a predetermined discharge cycle.

  In the first embodiment, the amount of one droplet is calculated in the preliminary ejection step, and thus a camera using an inexpensive CCD image sensor can be used for the imaging device 2 for imaging. It is designed as follows. Since the imaging capability of this imaging device is about 30 to 60 frames per second, when the droplet 9 during normal ejection is imaged, the image of the droplets 9A, 9B, and 9C is displayed in one frame image as shown in FIG. In this way, a plurality of droplets overlap. If the droplet amount is calculated based on the shifted image, an error occurs. For this reason, only one droplet 9 is imaged by low-speed preliminary discharge, and the amount of one droplet is calculated.

  In step S <b> 1, an ejection signal for preliminary ejection is output from the control device 8 to the droplet ejection device 5, and the droplet 9 is ejected from the ejection head 1. In step S2, the imaging device 2 images the droplet 9 ejected in step S1. In step S3, it is confirmed whether the image picked up in step S2 is normally ejected by the image processing apparatus 7 as shown in FIG. 4A, and FIG. 4B and FIG. If the discharge state is such as the discharge abnormality processing of step S11 is performed as the discharge abnormality. In the abnormal discharge process, a processing method suitable for a droplet discharge device (a portion provided with the discharge head 1, the discharge device 5, and the control device 8 in the droplet discharge amount detection device) is performed. A process for stopping the discharge is performed. In step S4, the image processing apparatus 7 binarizes the image captured in step S2, obtains the area or diameter of the droplet 9, calculates its volume under the condition that the droplet 9 is spherical, The amount of droplets.

  In step S <b> 5, a discharge signal is output from the control device 8 to the discharge device 5. The discharge signal in step S5 is output at a predetermined discharge cycle. In step S6, the control device 8 counts the discharge signal. The processing operation of the next step S7 is performed immediately after the ejection signal is counted in step S6. In this step S7, the count value of the ejection signal counted in step S6 by the control device 8 and the droplet obtained in step S8. Compare the count value. This time is immediately after counting the ejection signal in step S6, and the droplets 9 are not ejected from the ejection head 1, so the number of droplets 9 ejected in step S8 is not counted. Therefore, the number obtained by subtracting 1 from the count value of the ejection signal in step S6 is compared with the count value of the droplets in step S8. At this time, if the number obtained by subtracting 1 from the count value of the ejection signal in step S6 is not equal to the number of droplets in step S8, processing is performed as ejection abnormality. In step S <b> 8, the droplets 9 ejected from the ejection head 1 are counted by the detector 3 and the counting device 6. In step S9, the control device 8 confirms whether the discharge has been completed. In step S10, the droplet discharge amount is calculated by multiplying the droplet amount calculated in step S4 by the droplet number counted in step S8.

FIG. 9 shows the measurement result of the droplet discharge amount using the droplet discharge amount detection method of the first embodiment. The droplet discharge amount was measured by a droplet discharge amount detection device having the configuration shown in FIG. 1, and the nozzle 12 of the discharge head 1 was a nozzle having an inner diameter of 50 μm. The controller 8 outputs ejection signals 500, 750, 1000, 1250, 1500, 1750, 2000, 2250, and 2500 times to the ejection device 5, and measures the droplet ejection amount according to the flowchart shown in FIG. The normal discharge process was performed at a discharge cycle of 2 kHz. The operation of detecting the amount of the droplet 9 by preliminary discharge for calculating the amount of one droplet is calculated using the imaging device 2 and the image processing device 7, and the number of droplets 9 in the normal discharge step is counted. Is performed by the detector 3 and the counting device 6. The calculation of the droplet discharge amount was performed by multiplying the droplet amount of one droplet by the number of droplets counted by the counting device 6. The liquid used had a viscosity of 0.9 to 1.0 mPa · s at 25 ° C., a specific gravity of 1.1 g / cm ³ , and water as a solvent.

  FIG. 9A shows the droplet discharge amount obtained from the weight of each droplet number as proposed in Patent Document 1 and the number of droplets measured by the droplet discharge amount detection method of the present invention. 3 is a graph showing the average value of the droplet discharge amount in FIG. The horizontal axis indicates the number of droplets, and the vertical axis indicates the droplet discharge amount. The solid line in the figure is the average value of the droplet discharge amount calculated by the detection method of the first embodiment, and the broken line in the figure indicates the weight obtained by measuring the droplet discharge amount with a high-precision electronic balance. When measuring the weight, in order to avoid drying of the liquid after ejection, a container containing a liquid that has a specific gravity lighter than the liquid and does not evaporate was placed on the object 10 and the droplets 9 were ejected. In the first embodiment, a container in which oil is put on the object 10 is used. After discharging the droplets, the container was measured using a high-precision electronic balance to determine the weight, and the volume was calculated from the weight and specific gravity. The one-dot chain line and the two-dot chain line in the figure indicate the maximum value and the minimum value of the measurement tolerance in the first embodiment. Here, since ± 5% is an allowable range from the design value, + 5% and -5% of the volume obtained from the weight of each droplet number are represented by a one-dot chain line and a two-dot chain line. From the measurement results, it can be seen that the average value of the droplet discharge amount measured by the present invention is within ± 1.8% in the number of droplets.

  FIG. 9B is a graph showing the standard error of the droplet discharge amount calculated by the droplet discharge amount detection method. The horizontal axis indicates the number of droplets, and the vertical axis indicates the standard error in the measurement of the droplet discharge amount. The solid line in the figure shows the standard error of each droplet number. The standard error of measurement variation is also within ± 0.0025, which indicates that there is high stability even in repeated measurement.

  From the above results, using the droplet discharge amount detection method of the present invention, it is possible to accurately measure the total number of droplets discharged at high speed. In addition, since the ejection amount can be accurately controlled from the ejection droplets without impairing the high-speed operation, the functional liquid agent can be applied to the object 10 with a small amount and with high accuracy.

  In the first embodiment, the image pickup device 2 picks up an image of the droplet 9 discharged from the discharge head 1 by one preliminary discharge, and the image processing device 7 applies the liquid droplet 9 to the liquid. The amount of droplets is obtained, and the number of droplets is counted in real time by the detector 3 and the counting device 6, and the droplet amount calculated by the preliminary ejection is multiplied by the number of droplets counted by the counting device 6, and then ejected. By obtaining the droplet ejection amount from the head 1, all droplets can be detected in normal ejection performed at a high speed, and the ejection amount of all droplets by inkjet application can be accurately measured.

  In the first embodiment, when calculating the amount of one droplet of the image captured by the imaging device 2 by the image processing device 7, it is determined whether the captured image is normally ejected. The discharge generated by the satellite 9a, the droplet 9c smaller than the prescribed droplet diameter, and the like can be detected to detect the droplet discharge abnormality, and the reliability can be improved.

In the first embodiment, the counting device 6 has two threshold values and counts the number of droplets, thereby detecting the discharge generated by the satellite 9a or the discharge of the droplet 9c smaller than the specified droplet diameter. In addition, it is possible to detect a droplet discharge abnormality and improve the reliability.
(Embodiment 2)
FIG. 10 shows the configuration of a droplet discharge amount detection apparatus used in the droplet discharge amount detection method according to Embodiment 2 of the present invention. In FIG. 10, the same components as those in the droplet discharge amount detection device of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 10, the droplet discharge amount detection device according to the second embodiment is different from the droplet discharge amount detection device according to the first embodiment in that a predetermined amount of droplets discharged from the discharge head 1 is determined. The illumination control device 31 that controls the lighting of the light source 4 at the set number of ejections is provided. With this configuration, it is not necessary to calculate (detect) the droplet amount in advance during the preliminary discharge described in the first embodiment. That is, the illumination control device 31 can reliably image the droplet 9 with the imaging device 2 during the droplet discharge during the normal discharge in which the droplet is applied to the object 10 by continuously discharging at a cycle of 500 Hz to 5 kHz. With the goal. The illumination control device 31 connects the illumination signal of the control device 8 and the discharge device 5 and turns on the light source 4 only when the number of discharges set by the control device 8 at the time of droplet discharge from the discharge head 1 is discharged. The image is picked up by the image pickup device 2 and an image of one drop of the droplet 9 during normal discharge is picked up.

  FIG. 11 simply shows the configuration of the illumination control device 31 that controls the output of signals to the light source 4. The illumination control device 31 counts the discharge signal output from the control device 8 to the discharge device 5 by the digital counter 32. The comparator 33 compares the irradiation timing value for passing the light source 4 inputted in advance with the ejection signal output from the control device 8 to the ejection device 5 counted by the counter 32. If these two values match, the switch 34 is compared. Turn on. With this configuration, the illumination signal output from the ejection device 5 is synchronized with the ejection signal sent from the ejection device 5 to the ejection head. What is necessary is just to set the pulse width of the illumination signal output from the discharge apparatus 5 based on the period of a discharge signal. In this embodiment, it is set to 0.5 μs to 20 μs. The timing of the illumination signal can be freely set by changing the irradiation timing value input to the comparator 33. The output of the comparator 33 is input to the image processing device 7 as an image capture start signal. Therefore, it is possible to reliably capture an image of the droplet 9 obtained when the light source 4 is turned on. The area or diameter of the droplet is obtained from the captured image, and the amount of one droplet is calculated.

  FIG. 12 shows a flowchart of a droplet discharge amount detection method according to the second embodiment. In the droplet discharge amount detection method according to the second embodiment, discharge is performed from the discharge head 1 at a predetermined discharge cycle of 500 Hz to 5 kHz, and the light source 4 is turned on at a predetermined number of discharges during discharge. An image of the droplet 9 ejected at a predetermined number of ejections is acquired, the amount of one droplet is calculated, and the counting of the droplet 9 is performed by the detector 3 and the counting device 6 as in the first embodiment. The droplet discharge amount is obtained by multiplying the droplet amount of one droplet by the number of droplets counted by the counting device 6.

  In step S21, an irradiation timing value for turning on the light source 4 is output from the control device 8 to the illumination control device 31 at a predetermined number of ejections. In step S <b> 22, a discharge signal is output from the control device 8 to the discharge device value 5. The discharge signal in step S22 is output at a predetermined discharge cycle. In step S23, the illumination control device 31 counts the ejection signal in step S2. In step S24, the irradiation timing value set in step S21 is compared with the ejection signal count value in step S23. In step S25, when the irradiation timing value coincides with the count value of the ejection signal in step S24, the droplet 9 discharged by turning on the light source 4 is imaged with the imaging device value 2. In step S26, it is confirmed whether the image captured in step S25 is normally ejected by the image processing apparatus 7 as shown in FIG. 4A, and FIG. 4B, FIG. 4C, and the like. When the discharge state shown in FIG. 5 is reached, the discharge abnormality process (step S33) is performed as a discharge abnormality. In the abnormal discharge process, a processing method suitable for a droplet discharge device (a portion provided with the discharge head 1, the discharge device 5, and the control device 8 in the droplet discharge amount detection device) is performed. A process for stopping the discharge is performed. In step S27, the image processing apparatus 7 binarizes the image picked up in step S25, obtains the area or diameter of the droplet 9, calculates its volume under the condition that the droplet 9 is spherical, The amount of droplets.

  In step S28, the control device 8 counts the discharge signal. The processing operation of the next step S29 is performed immediately after the ejection signal is counted in step S22, and in this step S29, the count value of the ejection signal counted in step S28 by the control device 8 and the droplet obtained in step S10. Compare the count value. At this time, it is immediately after counting the ejection signal in step S28, and since the droplet 9 is not ejected from the ejection head 1, the droplet 9 ejected in step S30 is not counted. Therefore, the number obtained by subtracting 1 from the count value of the ejection signal in step S28 is compared with the count value of the droplets in step S30. At this time, if the number obtained by subtracting 1 from the count value of the ejection signal in step S28 is not equal to the number of droplets in step S30, the process is performed as ejection abnormality.

In step S <b> 30, the droplets 9 ejected from the ejection head 1 are counted by the detector 3 and the counting device 6.
In step S31, the control device 8 confirms whether the discharge has been completed. In step S32, the droplet discharge amount is calculated by multiplying the droplet amount calculated in step S27 by the droplet number counted in step S10.

FIG. 13 shows the measurement result of the droplet discharge amount using the droplet discharge amount detection method of the second embodiment. The droplet discharge amount was measured by a droplet discharge amount detection device having the configuration shown in FIG. 10, and the nozzle 12 of the discharge head 1 was a nozzle 12 having an inner diameter of 50 μm. The control device 8 outputs 500, 750, 1000, 1250, 1500, 1750, 2000, 2250, and 2500 discharge signals to the discharge device 5, and measures the droplet discharge amount according to the flowchart shown in FIG. In this case, the discharge cycle is 2 kHz. In order to calculate the amount of one droplet, for example, the light control device 31 is set so that the light source 4 is turned on when 100 droplets are ejected. The amount of one droplet was calculated using the processing device 7. The droplet 9 is counted by the detector 3 and the counting device 6. The calculation of the droplet discharge amount was performed by multiplying the droplet amount of one droplet by the number of droplets counted by the counting device 6. The liquid used had a viscosity of 0.9 to 1.0 mPa · s at 25 ° C., a specific gravity of 1.1 g / cm ³ , and water as a solvent.

  FIG. 13A shows a droplet discharge amount obtained from the weight of each droplet number as proposed in Patent Document 1, and each droplet number measured by the droplet discharge amount detection method of the present invention. 3 is a graph showing the average value of the droplet discharge amount in FIG. The horizontal axis indicates the number of droplets, and the vertical axis indicates the droplet discharge amount. The solid line in the figure is the average value of the droplet discharge amount calculated by the detection method of the second embodiment, and the broken line in the figure indicates the weight obtained by measuring the droplet discharge amount with a high-precision electronic balance. When measuring the weight, in order to avoid drying of the liquid after ejection, a container containing a liquid that has a specific gravity lighter than the liquid and does not evaporate was placed on the object 10 and the droplets 9 were ejected. In the second embodiment, a container in which oil is put on the object 10 is used. After discharging the droplets, the container was measured using a high-precision electronic balance to determine the weight, and the volume was calculated from the weight and specific gravity. The one-dot chain line and the two-dot chain line in the figure indicate the maximum value and the minimum value of the measurement tolerance in the first embodiment. Here, since ± 5% is an allowable range from the design value, + 5% and -5% of the volume obtained from the weight of each droplet number are represented by a one-dot chain line and a two-dot chain line. From the measurement results, it can be seen that the average value of the droplet discharge amount measured according to the present invention is accurate within ± 2.4% for each droplet number.

  FIG. 13B is a graph showing the standard error of the droplet discharge amount calculated by the droplet discharge amount detection method. The horizontal axis indicates the number of droplets, and the vertical axis indicates the standard error in the measurement of the droplet discharge amount. The solid line in the figure shows the standard error of each droplet number. The standard error of measurement variation is also within ± 0.0027, which indicates that there is high stability even in repeated measurement.

From the above results, using the droplet discharge amount detection method of the present invention, it is possible to accurately measure the total number of droplets discharged at high speed.
As described above, in the second embodiment, the illumination is turned on only when the number of discharges from the discharge head 1 is set using the illumination control device 31, and the droplets 9 at the set number of discharges are discharged. The image pick-up device 2 picks up an image, the image processing device 7 calculates the amount of liquid droplets per one drop, and the number of droplets is detected in real time by the detector 3 and the counting device 6. The number of droplets calculated by the image processing device 7 and the number of droplets counted by the counting device 6 are multiplied from the image of the droplet 9 at the set number of times of discharge and multiplied by the number of droplets counted by the counting device 6. By obtaining the amount, all droplets can be detected in normal ejection performed at high speed, and the ejection amount of droplet ejection by inkjet application can be accurately measured.

  Also in the second embodiment, when calculating the amount of one droplet of the image captured by the image capturing device 2 by the image processing device 7, it is determined whether or not the captured image is normally ejected. The discharge generated by the satellite 9a, the droplet 9c smaller than the prescribed droplet diameter, and the like can be detected to detect the droplet discharge abnormality, and the reliability can be improved.

  Also in the second embodiment, the counting device 6 has two threshold values to count the number of droplets, thereby discharging the satellites 9a and discharging the droplets 9c smaller than the prescribed droplet diameter. It is possible to detect and detect an abnormal discharge of droplets, and to improve reliability.

  The droplet discharge amount detection method and the droplet discharge amount detection device according to the present invention are for applications such as a droplet application method that requires accurate detection in real time of the discharge amount from an inkjet droplet discharge device. Applicable.

The figure which shows the structure of the droplet discharge amount detection apparatus in Embodiment 1 of this invention. The perspective view of the detector of the droplet discharge amount detection device The figure which shows simply the structure of the counter of the droplet discharge amount detection apparatus (A)-(c) is a figure for demonstrating the discharge state from the discharge head in the same droplet discharge amount detection apparatus, respectively. (A)-(c) is the figure which showed the output signal of the detector at the time of discharge in the droplet discharge amount detection method using the same droplet discharge amount detection apparatus, respectively. The figure which showed the meniscus state at the time of continuous discharge in the droplet discharge amount detection method The figure explaining the case where the continuous droplet is imaged in the droplet discharge amount detection method Flow chart of the droplet discharge amount detection method (A) And (b) is a figure which shows the measurement result of the droplet amount by the same droplet discharge amount detection method, respectively. The figure which shows the structure of the droplet discharge amount detection apparatus in Embodiment 2 of this invention. The figure which shows the structure of the illumination control apparatus of the droplet discharge amount detection apparatus Flow chart of droplet discharge amount detection method using the same droplet discharge amount detection device (A) And (b) is a figure which shows the measurement result of the droplet amount by the same droplet discharge amount detection method, respectively. The figure which shows the structure of the conventional droplet discharge amount detection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Discharge head 2 Imaging device 3 Detector 4 Light source 5 Discharge device 6 Counting device 7 Image processing device 8 Control device 9 Droplet 10 Object 11 Liquid agent tank 12 Nozzle 13 Light projecting portion 14 Light receiving portion 15 Laser light 16 Slit component 16a Slit 18a first threshold value 18b second threshold value 31 lighting control device 32 counter 33 comparator 34 switch

Claims (23)

A droplet discharge amount detection method for discharging a liquid agent onto the surface of an object after preliminary discharge,
A droplet amount calculating step for calculating the amount of droplets discharged during the preliminary discharge;
A droplet counting step for counting the number of droplets discharged to the object;
A droplet discharge amount calculation in which a value obtained by multiplying the droplet amount calculated in the droplet amount calculation step by the number of droplets counted in the droplet count step is a droplet discharge amount discharged onto the object. And a droplet discharge amount detecting method.   The droplet discharge amount detection method according to claim 1, wherein, in the droplet amount calculation step, a droplet diameter is measured, and the droplet amount is calculated using a calculation formula for a volume of a sphere based on the diameter.   The droplet discharge amount detection method according to claim 1, wherein the droplet amount calculation step includes a discharge normality determination step, and calculates the droplet amount only when the discharged droplet is determined to be normal.   In the ejection normality determining step, light is emitted to the droplet ejected onto the object to detect the amount of light when the droplet passes, and the amount of light when passing the droplet is different between the first threshold and the second threshold. 4. The droplet discharge amount detection method according to claim 3, wherein the droplet discharge amount detection method is determined to be normal when the light amount falls below the first threshold value and the second threshold value simultaneously.   The droplet discharge amount detection method according to claim 1, wherein the droplet counting step includes a discharge droplet collation step, and outputs the number of droplets counted only when the discharge droplet collation is determined to be normal.   In the ejection droplet collation step, the number obtained by subtracting 1 from the output pulse for outputting the droplet after preliminary ejection is compared with the number of droplets counted in the droplet counting step. The droplet discharge amount detection method according to claim 5. A droplet discharge amount detection method for a droplet discharge device that discharges a liquid onto the surface of an object,
An irradiation step of irradiating the droplets discharged onto the object with light;
A droplet amount calculating step of calculating a droplet amount per droplet from the droplets irradiated in the irradiation step;
A droplet counting step for counting the number of droplets discharged to the object;
A droplet discharge amount calculation in which a value obtained by multiplying the droplet amount calculated in the droplet amount calculation step by the number of droplets counted in the droplet count step is a droplet discharge amount discharged onto the object. And a droplet discharge amount detecting method.   8. The droplet discharge amount detection method according to claim 7, wherein, in the irradiation step, light is irradiated by a pulse output at a predetermined timing in synchronization with a drive pulse for discharging a droplet from the discharge head.   8. The droplet discharge amount detection method according to claim 7, wherein, in the droplet amount calculation step, the droplet diameter is measured, and the droplet amount is calculated using a sphere volume calculation formula based on the diameter.   8. The droplet discharge amount detection method according to claim 7, wherein the droplet amount calculation step includes a discharge normality determination step, and calculates the droplet amount only when the discharged droplet is determined to be normal.   In the ejection normality determining step, light is emitted to the droplet ejected onto the object to detect the amount of light when the droplet passes, and the amount of light when passing the droplet is different between the first threshold and the second threshold. The droplet discharge amount detection method according to claim 10, wherein comparison is made and it is determined that the light amount is normal when the light amount falls below the first threshold value and the second threshold value simultaneously.   8. The droplet discharge amount detection method according to claim 7, wherein the droplet counting step includes a discharge droplet collation step, and outputs the number of droplets counted only when the discharge droplet collation is determined to be normal. An ejection head for ejecting a liquid onto the surface of the object;
An ejection device that outputs a drive pulse for ejecting the liquid agent to the ejection head;
A light source for irradiating the droplets ejected from the ejection head with light;
An imaging device for imaging the ejected droplets;
A droplet detection device for detecting the discharged droplet;
A counting device for counting the number of detected droplets;
An image processing device for calculating a volume of the droplet from the image of the droplet acquired by the imaging device;
A control device that sets a multiplication amount obtained by multiplying the number of droplets counted by the counting device by the volume of the droplets calculated by the image processing device as a droplet discharge amount to be applied to the object from the discharge device; A droplet discharge amount detection device provided.   14. The droplet discharge amount detection device according to claim 13, wherein the counting device includes a plurality of counters having different threshold values, and outputs a count value of each counter to the control device.   The control device determines that the discharged droplets from the discharge head are normal droplets only when the count values from the plurality of counters match, and integrates the count values from the plurality of counters during the period during which the liquid agent is discharged to the object. The droplet discharge amount detection device according to claim 14, wherein the first integrated value is used.   The control device sets a value obtained by subtracting 1 from a value obtained by integrating the drive pulses during a period of discharging the liquid agent to the object as a second integrated value, and the first integrated value and the second integrated value coincide with each other. The droplet discharge amount detection apparatus according to claim 15, wherein only the normal discharge process is determined.   The control device calculates the volume of the droplet when the discharge droplet from the discharge head is determined to be a normal droplet, and the first integrated value or the second integrated value when the discharge normal processing is determined. The droplet discharge amount detection device according to claim 16, wherein a value obtained by multiplying the calculated droplet volume by a droplet is a droplet discharge amount to be applied to an object. An ejection head for ejecting a liquid onto the surface of the object;
An ejection device that outputs a drive pulse for ejecting the liquid agent to the ejection head;
A light source for irradiating the droplets ejected from the ejection head with light;
An illumination control device that controls irradiation of the light source at a predetermined irradiation timing connected to the light source and synchronized with the drive pulse;
An imaging device for imaging the ejected droplets at the irradiation timing;
A droplet detection device for detecting the discharged droplet;
A counting device for counting the number of detected droplets;
An image processing device for calculating a volume of the droplet from the image of the droplet acquired by the imaging device;
A control device that sets a multiplication amount obtained by multiplying the number of droplets counted by the counting device by the volume of the droplets calculated by the image processing device as a droplet discharge amount to be applied to the object from the discharge device; A droplet discharge amount detection device provided. The lighting control device includes a counter that counts drive pulses,
The output from the counter is compared with a set value given from the outside, and if these values match, the light source is controlled to irradiate light onto the droplets ejected from the ejection head as an irradiation timing. Item 19. A droplet discharge amount detection device according to Item 18.   19. The droplet discharge amount detection device according to claim 18, wherein the counting device includes a plurality of counters having different threshold values, and outputs a count value of each counter to the control device.   The control device determines that the discharge droplets from the discharge head are normal droplets only when the count values from the plurality of counters coincide with each other, and calculates the count values from the plurality of counters during the period during which the liquid agent is discharged onto the object. 21. The droplet discharge amount detection device according to claim 20, wherein the droplet discharge amount detection device is integrated to obtain a first integrated value.   The control device sets a value obtained by subtracting 1 from a value obtained by integrating drive pulses during a period during which the liquid agent is discharged to the object as a second integrated value, and the first integrated value and the second integrated value coincide with each other. 19. The droplet discharge amount detection device according to claim 18, wherein the droplet discharge amount detection apparatus determines that the discharge is normal only when the discharge is normal.   The control device calculates the volume of the droplet when it is determined that the discharged droplet from the discharge head is a normal droplet, and the first integrated value or the second integrated value when it is determined that the discharge normal processing is performed. The droplet discharge amount detection device according to claim 18, wherein a value obtained by multiplying a value by the calculated volume of the droplet is a droplet discharge amount to be applied to the object.

Images