JP5509509B2 - Droplet ejection device, droplet velocity adjustment method, droplet velocity detection device, droplet velocity detection method, program, and recording medium - Google Patents

Description

  The present invention relates to a droplet discharge device, a droplet velocity adjustment method, a droplet velocity detection device, a droplet velocity detection method, a program, and a recording medium, and more specifically, when detecting droplet velocity by image recognition, Droplet ejection device, droplet velocity adjustment method, droplet velocity detection device, droplet velocity detection method, which can accurately detect the droplet velocity even when the droplet is divided into a main droplet and a sub-droplet, The present invention relates to a program and a recording medium.

  Conventionally, the speed and amount of liquid droplets discharged from the recording head of an inkjet printer, etc. are detected, and the voltage value is set so that the liquid droplet speed and discharge amount become the target speed and target discharge amount based on the detected values. Patent Documents 1 and 2 disclose a droplet discharge device which is corrected.

  In the droplet discharge device described in Patent Document 1, a velocity measurement device that measures the velocity of a droplet discharged from a nozzle is provided, and the voltage value of the drive signal is corrected by feeding back the measurement value of the velocity measurement device. It is supposed to be. On the other hand, the droplet discharge device described in Patent Document 2 is provided with a discharge amount measurement device that measures the discharge amount, and is driven by multiplying the measurement value of the discharge amount measurement device by a correction coefficient to converge. The voltage value of the signal is corrected.

  In a droplet discharge device that corrects a driving condition such as a voltage value of a driving signal by feeding back a detection value obtained by detecting a droplet velocity, usually, a droplet velocity detecting operation and a driving condition correcting operation based on the detected value are performed. By performing this operation a plurality of times, the convergence operation for bringing the droplet velocity close to the target velocity is repeated. For this reason, unless the droplet velocity is accurately detected, the driving condition cannot be corrected accurately, and as a result, it becomes difficult to approach the target velocity in a short time.

As a method for detecting the droplet velocity, Japanese Patent Laid-Open No. 2004-26853 discloses that a droplet ejected from a nozzle is imaged by causing a strobe synchronized with a drive pulse to emit light twice, and the position coordinates and light emission of each captured droplet. A method for detecting the droplet velocity from the interval time is described.
Japanese Patent Application Laid-Open No. 7-256884 JP 2004-90621 A JP 2002-347224 A

  In general, the droplets are ejected from the nozzles by being separated from the ink meniscus in the nozzles in a state where a long and narrow tail is pulled backward in the flight direction. The tail of the ejected droplet is separated into a relatively large main droplet and a sub-droplet consisting of one or more small droplets called satellites so as to follow the main droplet. Although they are separated, as they fly further, they merge and become one droplet again.

  When imaging is performed twice at the time of detecting the droplet velocity, the first imaged liquid is separated into main droplets and sub-droplets (uncombined), and the liquid imaged the second time In some cases, the droplet has an unmerged-merged region where the main droplet and the sub-droplet are merged (merged).

  For example, FIG. 15 shows a result of imaging the droplets ejected from one nozzle by changing the voltage value of the driving voltage twice each. As can be seen from this, between 13V and 14V, the first and second droplets are not separated into main droplets and sub-droplets, but between 14V and 15V. In this case, the first imaged droplet is separated into a main droplet and a subdroplet, and the second imaged droplet is a combination of the main droplet and the subdroplet. Moreover, between 15V-16V, the droplet imaged the 1st time and the droplet imaged the 2nd time are isolate | separated into the main droplet and the subdroplet.

  Usually, when the droplet velocity is detected by imaging a droplet, it is performed by recognizing the captured droplet image, so that it is recognized within a predetermined image recognition range in order to separate it from the noise component. Since a predetermined threshold is provided for the area of the target image and an image having an area equal to or larger than this threshold is determined to be a droplet, a sub-droplet having a small area is excluded by the threshold and is not recognized as a droplet. . Therefore, the droplet imaged at the first time is separated into the main droplet and the sub-droplet, and the droplet imaged at the second time is merged with the main droplet and the sub-droplet (unmerged- In the case of merging), the droplet velocity is calculated based on the position coordinates of the center of gravity of only the main droplet imaged the first time and the position coordinates of the center of gravity of the merged droplet imaged the second time. Therefore, accurate droplet velocity detection is not performed.

  The occurrence conditions of the phenomenon in which the droplets are separated into the main droplets and the sub-droplets in this way vary depending on various conditions such as voltage value, environmental temperature, ink characteristics, and are not necessarily uniform. Accordingly, there is a problem that the droplet velocity is not accurately detected when the droplets ejected when the velocity is detected become unmerged-merged.

  In particular, the voltage correction is obtained in advance from the relationship between the droplet speed and driving conditions such as voltage value so that the droplet speed is detected for each nozzle and compared with the target speed, and the droplet speed becomes the target speed. When performing droplet speed adjustment work (hereinafter, such correction is referred to as DPN correction (Drive Per Nozzle correction)) that corrects the driving conditions using the coefficients, the allowable speed variation range is narrow. For this reason, it is necessary to accurately detect the droplet velocity. However, for example, as shown in FIG. 16, with the droplet velocity detected by image recognition of the droplet as shown in FIG. 15, for example, the sensitivity (Δvelocity) between 13V-14V, which is the coalescence-merging region, is shown. / Δ drive voltage value) is (5.2-4.0) / (14-13) = 1.2 m / s / V, while it is between 14V-15V, which is the unmerged-merged region. The sensitivity of (6.0−5.2) / (15−14) = 0.8 m / s / V is greatly deviated.

  Thus, since the sensitivity required by the droplet velocity detected by the droplets ejected in the unmerged-merged state includes a large error, the voltage correction coefficient which is the reciprocal of the sensitivity is also calculated incorrectly. Therefore, even if DPN correction is performed based on the inaccurately calculated voltage correction coefficient, there is a problem that the target speed is not easily approached and the number of times of convergence to the target speed increases.

  Also, in the case where both the first imaged droplet and the second imaged droplet are separated into a main droplet and a sub-droplet (unassembled-unassembled), Since it is excluded by the threshold value, strictly speaking, an accurate droplet velocity measurement is not performed, and there is a similar problem.

  Furthermore, when a droplet is imaged once and the droplet velocity is detected based on the position of the droplet at that time and the interval time from the droplet discharge trigger to the imaging, the droplet is divided into the main droplet and the sub-liquid. When separated into droplets, there is a problem that accurate droplet velocity detection is not performed as described above.

  Accordingly, the present invention provides a droplet discharge device capable of accurately detecting a droplet velocity and performing DPN correction accurately even when a discharged droplet is divided into a main droplet and a sub-droplet. Another object of the present invention is to provide a droplet velocity adjusting method, a program, and a recording medium.

  The present invention also provides a droplet velocity detection apparatus and droplet velocity detection method capable of accurately detecting the droplet velocity even when the ejected droplets are separated into a main droplet and a sub-droplet. It is an issue to provide.

  Other issues will become apparent from the following description.

  The above problems are solved by the following invention.

(Claim 1)
A head for generating droplet discharge energy for discharging droplets from a plurality of nozzles;
Driving means for driving the head based on a predetermined driving voltage value and discharging droplets from the nozzle;
By driving the driving means to eject droplets from the nozzles, imaging the droplets ejected from the same nozzle twice at different imaging timings, and recognizing the captured droplets as images, A droplet velocity detecting means for detecting a droplet velocity from a droplet position coordinate and an interval time of each imaging timing;
A voltage correction coefficient creating means for detecting a droplet speed by the droplet speed detecting means and creating a voltage correction coefficient based on a relationship between the detected droplet speed and a driving voltage value at that time;
The droplet velocity detected by the droplet velocity detection means is compared with the target velocity, and the droplet velocity detected by the droplet velocity detection means and the voltage correction coefficient are set so that the droplet velocity becomes the target velocity. calculating a new driving voltage by using the voltage correction coefficient generated by the generating means, the predetermined drive voltage possess the speed adjustment means for changing to the new drive voltage,
Droplet ejection in which the droplet velocity is detected by the droplet velocity detection means, the voltage correction coefficient is created by the voltage correction coefficient creation means, and a new drive voltage value is changed by the velocity adjustment means for each nozzle. In the device
When the voltage correction coefficient is created by the voltage correction coefficient creating means, the droplet velocity detecting means is configured to make at least one of the droplets imaged twice at the different imaging timings as a main droplet and a sub-liquid. It is determined whether or not the droplets are separated, and when it is determined that the droplets are separated, the predetermined drive voltage value is changed to a voltage value at which the droplets are not separated into main droplets and sub-droplets. to, again, have a row the detection of droplet velocity,
The droplet discharge device , wherein the droplet velocity detection means detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value .

(Claim 2)
A head for generating droplet discharge energy for discharging droplets from a plurality of nozzles;
Driving means for driving the head based on a predetermined driving voltage value and discharging droplets from the nozzle;
By driving the driving means to eject droplets from the nozzles, imaging the droplets ejected from the same nozzle twice at different imaging timings, and recognizing the captured droplets as images, A droplet velocity detecting means for detecting a droplet velocity from a droplet position coordinate and an interval time of each imaging timing;
A voltage correction coefficient creating means for detecting a droplet speed by the droplet speed detecting means and creating a voltage correction coefficient based on a relationship between the detected droplet speed and a driving voltage value at that time;
The droplet velocity detected by the droplet velocity detection means is compared with the target velocity, and the droplet velocity detected by the droplet velocity detection means and the voltage correction coefficient are set so that the droplet velocity becomes the target velocity. Speed adjustment means for calculating a new drive voltage value using the voltage correction coefficient created by the creation means and changing the predetermined drive voltage value to the new drive voltage value ;
Droplet ejection in which the droplet velocity is detected by the droplet velocity detection means, the voltage correction coefficient is created by the voltage correction coefficient creation means, and a new drive voltage value is changed by the velocity adjustment means for each nozzle. In the device
When the voltage correction coefficient is created by the voltage correction coefficient creating means, the droplet velocity detecting means is configured to make at least one of the droplets imaged twice at the different imaging timings as a main droplet and a sub-liquid. It is determined whether or not the liquid droplets are separated, and when it is determined that the liquid droplets are separated, the imaging timing is changed to a timing at which the liquid droplets are not separated into main liquid droplets and sub liquid droplets, and , Detect droplet velocity ,
The droplet discharge device, wherein the droplet velocity detection means detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value.

(Claim 3)
A head for generating droplet discharge energy for discharging droplets from a plurality of nozzles;
Driving means for generating a droplet discharge trigger based on a predetermined drive voltage value and driving the head to discharge a droplet from a nozzle;
By driving the driving means to eject droplets from the nozzle, imaging the droplets ejected from the nozzle, and recognizing the imaged droplets, the position coordinates of the droplets and the droplet ejection A droplet velocity detecting means for detecting a droplet velocity from an interval time from a trigger to imaging;
A voltage correction coefficient creating means for detecting a droplet speed by the droplet speed detecting means and creating a voltage correction coefficient based on a relationship between the detected droplet speed and a driving voltage value at that time;
The droplet velocity detected by the droplet velocity detection means is compared with the target velocity, and the droplet velocity detected by the droplet velocity detection means and the voltage correction coefficient are set so that the droplet velocity becomes the target velocity. Speed adjustment means for calculating a new drive voltage value using the voltage correction coefficient created by the creation means and changing the predetermined drive voltage value to the new drive voltage value ;
Droplet ejection in which the droplet velocity is detected by the droplet velocity detection means, the voltage correction coefficient is created by the voltage correction coefficient creation means, and a new drive voltage value is changed by the velocity adjustment means for each nozzle. In the device
The droplet velocity detection means determines whether or not the imaged droplet is separated into a main droplet and a sub-droplet when the voltage correction coefficient is created by the voltage correction coefficient creation means. The predetermined drive voltage value is changed to a voltage value at which the droplet does not separate into a main droplet and a sub-droplet, and the droplet velocity is detected again ,
The droplet discharge device , wherein the droplet velocity detection means detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value .

(Claim 4)
A head for generating droplet discharge energy for discharging droplets from a plurality of nozzles;
Driving means for generating a droplet discharge trigger based on a predetermined drive voltage value and driving the head to discharge a droplet from a nozzle;
By driving the driving means to eject droplets from the nozzle, imaging the droplets ejected from the nozzle, and recognizing the imaged droplets, the position coordinates of the droplets and the droplet ejection A droplet velocity detecting means for detecting a droplet velocity from an interval time from a trigger to imaging;
A voltage correction coefficient creating means for detecting a droplet speed by the droplet speed detecting means and creating a voltage correction coefficient based on a relationship between the detected droplet speed and a driving voltage value at that time;
The droplet velocity detected by the droplet velocity detection means is compared with the target velocity, and the droplet velocity detected by the droplet velocity detection means and the voltage correction coefficient are set so that the droplet velocity becomes the target velocity. Speed adjustment means for calculating a new drive voltage value using the voltage correction coefficient created by the creation means and changing the predetermined drive voltage value to the new drive voltage value ;
Droplet ejection in which the droplet velocity is detected by the droplet velocity detection means, the voltage correction coefficient is created by the voltage correction coefficient creation means, and a new drive voltage value is changed by the velocity adjustment means for each nozzle. In the device
The droplet velocity detection means determines whether or not the imaged droplet is separated into a main droplet and a sub-droplet when the voltage correction coefficient is created by the voltage correction coefficient creation means. If it is determined, the interval time from the droplet discharge trigger to imaging is changed to an interval time at which the droplet does not separate into the main droplet and the sub-droplet, and the droplet velocity is detected again. Yes,
The droplet discharge device , wherein the droplet velocity detection means detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value .

(Claim 5 )
The droplet velocity detection means recognizes an image having a recognition area equal to or larger than a predetermined area when an image of the captured droplet is recognized as a droplet, and images the first and second droplets. It is determined whether or not the difference in area from the liquid droplet is greater than or equal to a predetermined value. in which a liquid droplet ejection apparatus according to claim 1 or 2, wherein the determining.

(Claim 6 )
The droplet velocity detection means recognizes an image whose recognition area when a captured droplet is recognized as an image is a predetermined area or more, and recognizes the recognized area of the captured droplet as a main memory previously stored. It is determined whether or not the difference between the combined area of the droplet and the sub-droplet is greater than or equal to a predetermined value, and if it is determined that the difference is greater than or equal to the predetermined value, the droplet is the main droplet and sub-droplet the apparatus according to any one of claims 1 to 4, characterized in that to determine that separated into and.

(Claim 7)
The droplet velocity detection means recognizes all of the captured droplet images within the image recognition range as droplets, counts the number of droplet images within the image recognition range, and the count value is 2 or more. 5. The droplet discharge device according to claim 1, wherein, when determined, the droplet is determined to be separated into a main droplet and a sub-droplet.

(Claim 8 )
Each droplet is ejected from a nozzle with a predetermined drive voltage value, the droplet ejected from the same nozzle is imaged twice at different imaging timings, and each captured droplet is recognized as an image. Detecting a droplet velocity from the position coordinates of each and the interval time of each imaging timing;
Detecting a discharged droplet velocity to create a voltage correction coefficient based on a relationship between the droplet velocity and a driving voltage value at that time;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. was closed and a step of changing to the new drive voltage,
In the droplet velocity adjusting method , wherein the step of detecting the droplet velocity, the step of creating the voltage correction coefficient, and the step of changing to the new drive voltage value are performed for each of a plurality of nozzles .
The step of creating the voltage correction coefficient includes separating at least one of the droplets imaged twice at the different imaging timings into a main droplet and a sub-droplet when detecting a droplet velocity. And if it is determined that the head is separated, the predetermined drive voltage value of the head is changed to a voltage value at which the droplet does not separate into a main droplet and a sub-droplet. , Again detect the droplet velocity ,
The method of adjusting a droplet speed, wherein the step of detecting the droplet velocity detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value .

(Claim 9 )
Each droplet is ejected from a nozzle with a predetermined drive voltage value, the droplet ejected from the same nozzle is imaged twice at different imaging timings, and each captured droplet is recognized as an image. Detecting a droplet velocity from the position coordinates of each and the interval time of each imaging timing;
Detecting a discharged droplet velocity to create a voltage correction coefficient based on a relationship between the droplet velocity and a driving voltage value at that time;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. was closed and a step of changing to the new drive voltage,
In the droplet velocity adjusting method , wherein the step of detecting the droplet velocity, the step of creating the voltage correction coefficient, and the step of changing to the new drive voltage value are performed for each of a plurality of nozzles .
The step of creating the voltage correction coefficient includes separating at least one of the droplets imaged twice at the different imaging timings into a main droplet and a sub-droplet when detecting a droplet velocity. If it is determined that the droplets are separated, the imaging timing is changed to a timing at which the droplets are not separated into main droplets and sub-droplets, and the droplet velocity is changed again. It performs detection,
The method of adjusting a droplet speed, wherein the step of detecting the droplet velocity detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value .

(Claim 10 )
By generating a droplet discharge trigger at a predetermined drive voltage value, discharging a droplet from the nozzle, imaging the droplet discharged from the nozzle, and recognizing the image of the captured droplet, Detecting a droplet velocity from a position coordinate and an interval time from the droplet discharge trigger to imaging;
Detecting a discharged droplet velocity to create a voltage correction coefficient based on a relationship between the droplet velocity and a driving voltage value at that time;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. was closed and a step of changing to the new drive voltage,
In the droplet velocity adjusting method , wherein the step of detecting the droplet velocity, the step of creating the voltage correction coefficient, and the step of changing to the new drive voltage value are performed for each of a plurality of nozzles .
In the step of creating the voltage correction coefficient, it is determined whether or not the droplet imaged at the time of detecting the droplet velocity is separated into a main droplet and a sub-droplet. In addition, the predetermined driving voltage value of the head is changed to a voltage value at which the droplet does not separate into a main droplet and a sub-droplet, and the droplet velocity is detected again ,
The method of adjusting a droplet speed, wherein the step of detecting the droplet velocity detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value .

(Claim 11 )
By generating a droplet discharge trigger at a predetermined drive voltage value, discharging a droplet from the nozzle, imaging the droplet discharged from the nozzle, and recognizing the image of the captured droplet, Detecting a droplet velocity from a position coordinate and an interval time from the droplet discharge trigger to imaging;
Detecting a discharged droplet velocity to create a voltage correction coefficient based on a relationship between the droplet velocity and a driving voltage value at that time;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. was closed and a step of changing to the new drive voltage,
In the droplet velocity adjusting method , wherein the step of detecting the droplet velocity, the step of creating the voltage correction coefficient, and the step of changing to the new drive voltage value are performed for each of a plurality of nozzles .
In the step of creating the voltage correction coefficient, it is determined whether or not the droplet imaged at the time of detecting the droplet velocity is separated into a main droplet and a sub-droplet. In addition, the interval time from the droplet discharge trigger to imaging is changed to an interval time in which the droplet does not separate into a main droplet and a sub-droplet, and the droplet velocity is detected again,
The method of adjusting a droplet speed, wherein the step of detecting the droplet velocity detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value .

(Claim 12 )
The step of creating the voltage correction coefficient recognizes an image having a recognition area equal to or larger than a predetermined area when the imaged droplet is recognized as a droplet, and the first imaged droplet and the second time It is determined whether or not the difference in area from the imaged droplet is greater than or equal to a predetermined value. 10. The droplet speed adjusting method according to claim 8, wherein it is determined that the droplets are separated.

(Claim 13 )
In the step of creating the voltage correction coefficient, an image whose recognition area when the captured droplet is recognized is recognized as a droplet, and the recognized area of the captured droplet is stored in advance. It is determined whether or not the difference between the combined area of the main droplet and the sub-droplet is equal to or greater than a predetermined value. It is judged that it has isolate | separated into the droplet, The droplet speed adjustment method in any one of Claims 8-11 characterized by the above-mentioned.

(Claim 14 )
The step of creating the voltage correction coefficient recognizes all the captured droplet images within the image recognition range as droplets, counts the number of droplet images within the image recognition range, and the count value is 2 or more. 12. The droplet speed adjusting method according to claim 8 , wherein when it is determined that there is a droplet, it is determined that the droplet is separated into a main droplet and a sub-droplet.

(Claim 15 )
The liquid droplets ejected from the same nozzle based on a predetermined drive voltage value are imaged twice at different imaging timings, and each captured liquid droplet is image-recognized, whereby the position coordinates of each liquid droplet and each of the liquid droplets are recognized. In the droplet velocity detection device that detects the droplet velocity from the interval time of the imaging timing of
A determination means for determining whether at least one of the captured droplets is separated into a main droplet and a sub-droplet;
Control that detects the droplet velocity again by changing the imaging timing to a timing at which the droplet does not separate into a main droplet and a sub-droplet when the determination unit determines that the droplet is separated. Means for detecting a droplet velocity.

(Claim 16 )
By imaging a droplet ejected from a nozzle by a droplet ejection trigger generated based on a predetermined driving voltage value and recognizing the captured droplet, the position coordinates of the droplet and the droplet ejection In a droplet velocity detection device that detects a droplet velocity from an interval time from a trigger to imaging,
Determining means for determining whether or not the imaged droplet is separated into a main droplet and a sub-droplet;
When it is determined by the determination means that the separation is performed, the interval time from the droplet discharge trigger to imaging is changed to an interval time at which the droplet is not separated into the main droplet and the sub-droplet, and again And a droplet velocity detection apparatus comprising a control means for detecting the droplet velocity.

(Claim 17 )
The determination means recognizes an image having a recognition area of a predetermined area or more when the captured droplet is recognized as a droplet, and at the same time, the first captured droplet and the second captured droplet. And whether or not the difference in area is greater than or equal to a predetermined value, and if it is determined that the difference is greater than or equal to a predetermined value, any of the droplets is separated into a main droplet and a sub-droplet The droplet velocity detection device according to claim 15 , wherein the determination is made.

(Claim 18 )
The determination means recognizes an image whose recognized area when a captured droplet is recognized as an image is a predetermined area or more, and recognizes the recognized area of the captured droplet and a main droplet stored in advance. It is determined whether or not the difference between the combined area of the sub-droplet and the area is greater than or equal to a predetermined value, and when it is determined that the difference is greater than or equal to the predetermined value, the liquid droplet is separated into main and sub-droplets The droplet velocity detection device according to claim 15 or 16 , wherein the droplet velocity detection device determines that the droplet velocity is detected.

(Claim 19 )
The determination means recognizes all the captured droplet images within the image recognition range as droplets, counts the number of droplet images within the image recognition range, and determines that the count value is 2 or more. case, the droplet speed detecting apparatus according to claim 15 or 16, wherein the determining the droplet is separated into a main droplet and the auxiliary liquid droplets.

(Claim 20 )
The liquid droplets ejected from the same nozzle based on a predetermined drive voltage value are imaged twice at different imaging timings, and each captured liquid droplet is image-recognized, whereby the position coordinates of each liquid droplet and In the droplet velocity detection method for detecting the droplet velocity from the interval time of the imaging timing of
It is determined whether or not at least one of the imaged droplets is separated into a main droplet and a sub-droplet. A droplet velocity detection method, wherein the droplet velocity is detected again after changing to a timing at which the droplets and sub-droplets are not separated.

(Claim 21 )
By imaging a droplet ejected from a nozzle by a droplet ejection trigger generated based on a predetermined drive voltage value and recognizing the captured droplet, the position coordinates of the droplet and the droplet ejection In a droplet velocity detection method for detecting a droplet velocity from an interval time from a trigger to imaging,
It is determined whether or not the imaged droplet is separated into a main droplet and a sub-droplet. If it is determined that the droplet is separated, an interval time from the droplet discharge trigger to imaging is determined as the liquid droplet. A droplet velocity detection method, wherein the droplet velocity is detected again after changing to an interval time during which the droplet does not separate into a main droplet and a sub-droplet.

(Claim 22 )
An image in which the recognized area when the captured droplet is recognized is recognized as a droplet, and the difference in area between the first captured droplet and the second captured droplet Is determined to be greater than or equal to a predetermined value, and if it is determined to be greater than or equal to a predetermined value, it is determined that any droplet is separated into a main droplet and a sub-droplet. The droplet velocity detection method according to claim 20 .

(Claim 23 )
Recognize an image whose recognition area when the captured droplet is recognized as a predetermined area or more as a droplet, and recognize the recognized area of the captured droplet and the main and sub-droplets stored in advance. It is determined whether or not the difference from the combined area is greater than or equal to a predetermined value, and if it is determined that the difference is greater than or equal to a predetermined value, it is determined that the droplet is separated into a main droplet and a sub-droplet The droplet velocity detection method according to claim 20 or 21, wherein:

(Claim 24 )
When all of the captured droplet images within the image recognition range are recognized as droplets, the number of droplet images within the image recognition range is counted, and when it is determined that the counted value is 2 or more, the liquid image The droplet velocity detection method according to claim 20 or 21, wherein it is determined that the droplet is separated into a main droplet and a sub-droplet.

(Claim 25 )
On the computer,
Each droplet is ejected from a nozzle with a predetermined drive voltage value, the droplet ejected from the same nozzle is imaged twice at different imaging timings, and each captured droplet is recognized as an image. the position coordinates of the the interval time of each imaging timing and ability to detect the drop velocity from
A function of creating a voltage correction coefficient based on the relationship between the droplet velocity and the driving voltage value at that time by detecting the ejected droplet velocity;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. the and a function to change the new drive voltage,
Realizing the function of detecting the droplet velocity, the function of creating the voltage correction coefficient, and the function of changing to the new drive voltage value for each of a plurality of nozzles ,
The function of creating the voltage correction coefficient is to separate at least one of the droplets imaged twice at the different imaging timings when detecting the droplet velocity into a main droplet and a sub-droplet. And if it is determined that the head is separated, the predetermined drive voltage value of the head is changed to a voltage value at which the droplet does not separate into a main droplet and a sub-droplet. Realize the function to detect the droplet velocity again ,
The solution function of detecting the drop speed, the program characterized by Rukoto to realize the function of detecting the drop velocity even after the change to the new drive voltage value to adjust the drop velocity.

(Claim 26 )
On the computer,
Each droplet is ejected from a nozzle with a predetermined drive voltage value, the droplet ejected from the same nozzle is imaged twice at different imaging timings, and each captured droplet is recognized as an image. A function of detecting the droplet velocity from the position coordinates of each and the interval time of each imaging timing,
A function of creating a voltage correction coefficient based on the relationship between the droplet velocity and the driving voltage value at that time by detecting the ejected droplet velocity;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. the and a function to change the new drive voltage,
Realizing the function of detecting the droplet velocity, the function of creating the voltage correction coefficient, and the function of changing to the new drive voltage value for each of a plurality of nozzles ,
The function of creating the voltage correction coefficient is to separate at least one of the droplets imaged twice at the different imaging timings when detecting the droplet velocity into a main droplet and a sub-droplet. If it is determined that the droplets are separated, the imaging timing is changed to a timing at which the droplets are not separated into main droplets and sub-droplets, and the droplet velocity is changed again. Realize the function to detect ,
The solution function of detecting the drop speed, the program characterized by Rukoto to realize the function of detecting the drop velocity even after the change to the new drive voltage value to adjust the drop velocity.

(Claim 27 )
On the computer,
By generating a droplet discharge trigger at a predetermined drive voltage value, discharging a droplet from the nozzle, imaging the droplet discharged from the nozzle, and recognizing the image of the captured droplet, A function of detecting a droplet velocity from a position coordinate and an interval time from the droplet discharge trigger to imaging;
A function of creating a voltage correction coefficient based on the relationship between the droplet velocity and the driving voltage value at that time by detecting the ejected droplet velocity;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. the and a function to change the new drive voltage,
Realizing the function of detecting the droplet velocity, the function of creating the voltage correction coefficient, and the function of changing to the new drive voltage value for each of a plurality of nozzles ,
The function of creating the voltage correction coefficient is to determine whether or not the droplet imaged at the time of detecting the droplet velocity is separated into a main droplet and a sub-droplet. In addition, the predetermined drive voltage value of the head is changed to a voltage value at which the droplet is not separated into a main droplet and a sub-droplet, and a function of detecting a droplet velocity is realized again .
The solution function of detecting the drop speed, the program characterized by Rukoto to realize the function of detecting the drop velocity even after the change to the new drive voltage value to adjust the drop velocity.

(Claim 28 )
On the computer,
By generating a droplet discharge trigger at a predetermined drive voltage value, discharging a droplet from the nozzle, imaging the droplet discharged from the nozzle, and recognizing the image of the captured droplet, A function of detecting a droplet velocity from a position coordinate and an interval time from the droplet discharge trigger to imaging;
A function of creating a voltage correction coefficient based on the relationship between the droplet velocity and the driving voltage value at that time by detecting the ejected droplet velocity;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. the and a function to change the new drive voltage,
Realizing the function of detecting the droplet velocity, the function of creating the voltage correction coefficient, and the function of changing to the new drive voltage value for each of a plurality of nozzles ,
The function of creating the voltage correction coefficient is to determine whether or not the droplet imaged at the time of detecting the droplet velocity is separated into a main droplet and a sub-droplet. In addition, the interval time from the droplet discharge trigger to imaging is changed to an interval time in which the droplet is not separated into the main droplet and the sub-droplet, and the function of detecting the droplet velocity is realized again.
The solution function of detecting the drop speed, the program characterized by Rukoto to realize the function of detecting the drop velocity even after the change to the new drive voltage value to adjust the drop velocity.

(Claim 29 )
A recording medium storing the program according to any one of claims 25 to 28 .

  According to the present invention, even when the ejected droplets are divided into main droplets and sub-droplets, the droplet ejection device can accurately detect the droplet velocity and perform DPN correction accurately. A droplet speed adjusting method, a program, and a recording medium can be provided.

  In addition, according to the present invention, a droplet velocity detecting device and a droplet velocity that can accurately detect the droplet velocity even when the ejected droplet is divided into a main droplet and a sub-droplet. A detection method can be provided.

  Embodiments of the present invention will be described below.

  FIG. 1 is a diagram showing a configuration example of a system which is an example of a droplet velocity detection device according to the present invention.

  In FIG. 1, reference numeral 1 denotes an ink jet head that ejects liquid droplets (ink droplets). Although the inkjet head 1 is not specifically limited, For example, a share mode piezo type inkjet head can be used. An ink jet head that can be preferably applied to the present invention will be described with reference to FIGS.

  FIG. 2 is a block diagram of the shear mode piezo ink jet head, and FIG. 3 is a cross-sectional view of the actuator cut at right angles to the channel flow path direction.

  As shown in FIGS. 2 and 3, a groove is mechanically formed in a PZT substrate 100 formed by bonding two piezoelectric materials having different polarization directions, whereby an actuator 103 which is a channel 101 and a channel wall 102 is formed. Is formed. A nozzle plate 106 having a cover plate 104 on its upper surface and a nozzle 105 on its front surface is bonded. The channel 101 is filled with ink from the common ink supply chamber 107. Reference numeral 108 denotes a wiring portion.

  An electrode 109 is formed on the surface of the channel wall 102, and the channel wall 102 is bent and deformed by applying an electric field in a direction perpendicular to the polarization direction (vertical direction in the drawing) of the PZT substrate 100. To generate energy for discharging. The pressure generated in the channel 101 is reflected at the boundary between the nozzle 105 and the common ink supply chamber 107 and resonates, whereby the pressure applied to the nozzle 105 changes over time, and droplets are ejected.

  Next, in FIG. 1, reference numeral 2 denotes a droplet detection unit, a strobe 200 that is a light emitting unit that emits light, and a CCD camera that is an imaging unit that receives the light emitted from the strobe 200 and images a droplet. 201.

  Note that the light emitting means is not limited to the strobe 200 as long as it can irradiate the droplets with light during imaging. As the light emitting means, in addition to the strobe 200, for example, an LED or the like may be used.

  The imaging unit is not limited to the CCD camera 201 as long as it can receive light from the light emitting unit and image a droplet. As the imaging means, for example, a CMOS camera or the like may be used in addition to the CCD camera 201.

Furthermore, a high-speed shutter camera can also be used as the imaging means. The high-speed shutter camera can capture images at a high speed of about 10 ⁶ times per second at a maximum, and can be used to obtain a droplet image discharged from the nozzle. In the following description, it is assumed that the strobe 200 and the CCD camera 201 that can be configured relatively inexpensively are used.

  Reference numeral 3 denotes a PC (computer), for example, a setting input unit 300 for inputting a setting value such as a strobe delay time, and the position of the center of gravity of one or more droplets from image data obtained by imaging with the CCD camera 201. At least an image processing unit 301 for calculation is provided. The method for calculating the position of the center of gravity of the droplet is not particularly limited, but the image of the captured droplet is compared with the reference table (sample shape and position of the center of gravity are specified), and a similar shape is selected to determine the center of gravity. A method for determining the position may be mentioned. The position of the center of gravity can be calculated as X and Y coordinate values.

  Note that droplet discharge for droplet detection is preferably performed by a maintenance unit (not shown) arranged outside the recording area on the recording paper or the like. In this case, the strobe 200 and the CCD camera 201 are used. Is preferably provided in the vicinity of the maintenance unit.

  A data control board 4 is connected to the PC 3, the DPN drive board 5, and the strobe 200, and controls them as well as controls for detecting the velocity of the droplets ejected from the inkjet head 1.

  Reference numeral 6 denotes a drive waveform generator that sends a drive waveform signal to the DPN drive substrate 5, 7 denotes a drive voltage control unit, 8 denotes a power source, and 9 denotes an offset power source.

  Next, details of the DPN drive substrate 5 will be described with reference to FIGS.

  FIG. 4 is a circuit diagram illustrating a schematic configuration of the DPN drive board 5, and the DPN drive board 5 includes a drive waveform creation unit 500 and a drive signal output unit 501.

  The DPN drive substrate 5 is connected to the data control substrate 4 constituting the control unit, and outputs a drive signal (droplet discharge trigger) having a waveform based on the control signal from the data control substrate 4 to the inkjet head 1. Connected to the data control board 4 is a waveform generator 500 that forms a waveform of a drive signal corresponding to the actuator 103. A plurality of AND elements (not shown) are mounted on the waveform creating unit 500 so as to correspond to the respective nozzles 105.

  A data control board 4 and a drive waveform generator 6 are connected to the AND element, and a drive signal from the data control board 4 and an adjustment signal from the drive waveform generator 6 are input to synthesize these signals. Thus, a driving signal (droplet discharge trigger) having a waveform necessary for driving is output.

  On the other hand, the drive voltage control unit 7 is connected to the data control board 4 and determines a voltage value based on a control signal from the data control board 4. The voltage control unit 7 includes a D / A converter 700 that converts a control signal from the data control board 4 into an analog signal, and an amplifier 701 that amplifies the analog signal from the D / A converter 700 to a predetermined voltage value. Are provided so as to correspond to each nozzle 105. An offset power supply 9 for supplying offset power and a D / A converter 700 are connected to the input terminal of the amplifier 701.

  Then, in the drive circuit of the DPN drive substrate 5, the drive signal from the waveform creation unit 500 and the voltage value from the voltage control unit 7 are combined, and a drive signal (droplet discharge trigger) having a waveform independent of each nozzle 105 is provided. A drive signal output unit 501 is provided for generation. The drive signal output unit 501 is provided with a plurality of FET elements 502. The input terminal of each FET element 502 is connected to the output terminal of the AND element of the waveform generator 500 and the output terminal of the amplifier 701 of the voltage controller 7, and the electrode 109 of the actuator 103 is connected to the output terminal. Has been. As a result, the FET element 502 synthesizes the drive signal from the waveform generator 500 and the voltage value from the voltage controller 7 to each nozzle 105 and outputs it to the electrode 109 of the actuator 103.

  Hereinafter, an example of the droplet speed adjusting method according to the present invention will be described.

(About DPN correction)
In the present invention, an operation for performing DPN correction for correcting the driving condition of each nozzle will be described. FIG. 5 is a process flowchart showing the DPN correction process.

  DPN correction is performed for each nozzle 105 and the same processing is performed for all nozzles 105. When performing this DPN correction, the droplets ejected at a specific drive voltage may have been divided into main droplets and sub-droplets in the past, and the exact gravity center position cannot be grasped and the accurate droplet velocity can be obtained. Although it was difficult to detect, in the present invention, an accurate droplet velocity can be detected by detecting an accurate center-of-gravity position. Therefore, DPN correction is performed based on an accurate detected value of the droplet velocity. Can do.

  Here, it is assumed that the voltage value of the drive signal for discharging droplets is corrected as the drive condition. Therefore, in this DPN correction, first, the droplet velocity is detected using at least two or more drive signals having different voltage values, and a voltage correction coefficient α that is the reciprocal of sensitivity (Δspeed / Δdrive voltage value) is obtained. (S1).

  FIG. 6 shows an example of a processing flow for calculating the voltage correction coefficient α.

  Here, each droplet ejected from all nozzles at the same timing is imaged twice in total by the strobe 200 and the CCD camera 201 at each imaging timing of the strobe delay time (1) and the strobe delay time (2). Each process is performed. Here, for the same droplet ejected from the nozzle, the droplet imaged at the timing of the first strobody lay time (1) is the “droplet 1” and the timing of the second strobody lay time (2). The imaged droplet is referred to as “droplet 2”.

  In advance, the setting input unit 300 of the computer 3 sets the strobe delay time (1) and the drive voltage value (1) (S101).

  The strobody lay time (1) is a timing at which a droplet is ejected to the inkjet head 1, for example, a delay time from when the stroboscope 200 is caused to emit light to be imaged by the CCD camera 201 from a droplet ejection trigger. On the other hand, it is the time for the first imaging. Further, the drive voltage value (1) is a drive voltage value for first discharging a droplet. The settings of the strobe delay time (1) and the drive voltage value (1) can be stored in advance.

  In general, the droplet velocity is represented by the distance traveled between each imaged droplet / the interval time from the imaging timing of the droplet 1 to the imaging timing of the droplet 2.

  Next, a droplet is ejected from an arbitrary nozzle according to the drive voltage value (1), and after the delay time set by the strobe delay time (1) has elapsed, the strobe 200 is caused to emit light and the CCD camera 201 images the droplet 1. The captured image is sent to the image processing unit 301.

  The image processing unit 301 determines a predetermined image recognition range from the transmitted image, recognizes an image having an image area equal to or larger than a predetermined threshold among images within the image recognition range, and recognizes the recognized image. Is an image of the droplet 1. After the image of the droplet 1 is determined, the position coordinate (X1, Y1) of the center of gravity is calculated from the area center of gravity (or volume center of gravity) of the droplet 1 (S102).

  Next, the strobe delay time (2) is set (S103). The Strobody lay time (2) is a time set so as to be a predetermined delay time from the Strobody lay time (1). This strobodilay time (2) can also be stored in advance.

  Next, after the delay time set by the strobody lay time (2) has elapsed, the stroboscope 200 is caused to emit light again, and the CCD camera 201 continues to image the droplet 2. The captured image is sent to the image processing unit 301.

  The image processing unit 301 determines a predetermined image recognition range from the transmitted image, recognizes an image having an image area equal to or larger than a predetermined threshold among images within the image recognition range, and recognizes the recognized image. Is an image of the droplet 2. After the image of the droplet 2 is determined, the position coordinates (X2, Y2) of the center of gravity are calculated from the area center of gravity (or volume center of gravity) of the droplet 2 (S104).

  Next, the recognition area of the droplet 1 obtained in S102 is compared with the recognition area of the droplet 2 obtained in S104 (S105). If one of the recognized droplet 1 and droplet 2 (usually droplet 1) is separated into a main droplet and a sub-droplet, the sub-droplet is excluded by the threshold and is not recognized. In the case of the droplet 1, the recognition area of only the main droplet is obtained, and in the case of the droplet 2, the recognition area of the combined droplet is obtained. Accordingly, when the recognition area of the droplet 1 is smaller than the recognition area of the droplet 2 by comparison between the recognition area of the droplet 1 and the recognition area of the droplet 2, the droplet 1 is the main one. It can be determined that the droplets are separated into sub-droplets. Here, as an example, it is determined whether or not the recognized area of the droplet 1 exceeds 90% of the recognized area of the droplet 2, but this value may be set as appropriate according to various conditions such as environmental temperature and ink characteristics. .

  Here, when the imaged droplet 1 and droplet 2 are not separated into a main droplet and a sub-droplet (combination-combination) as shown in FIG. The droplet velocity obtained from each image of the recognized droplet 1 and droplet 2 shows an accurate value from the position of the accurate center of gravity of the droplet 1 and droplet 2. However, as shown in FIG. 7B, the imaged droplet 1 is separated into a main droplet and a sub-droplet, and the droplet 2 is not separated (unassembled-unioned). In some cases, the sub-droplet of the droplet 1 is excluded at the threshold during image recognition and is not recognized as a droplet image, but only the main droplet is recognized as the image of the droplet 1. Since the main droplet has a smaller area than the droplet 2 that is not separated into the main droplet and the sub-droplet because the sub-droplet is separated, the recognition area of the droplet 1 and the droplet 2 is compared with the recognition area of 2 and it is determined whether or not the recognition area of the droplet 1 exceeds 90% of the recognition area of the droplet 2. It can be determined whether or not they are separated.

  As a result, if Yes in S105, that is, if the recognition area of the droplet 1 exceeds 90% of the recognition area of the droplet 2, the droplet 1 and the droplet 2 are shown in FIG. As shown, it is determined that none of the liquid droplets is separated into main droplets and sub-droplets. Accordingly, the droplet velocity is calculated by using the position coordinates of the center of gravity of each of the droplets 1 and 2 and the strobody lay time (1) and the strobody lay time (2) (S106). The droplet velocity can be obtained by the following formula.

  When the answer is No in S105, that is, when the recognition area of the droplet 1 does not exceed 90% of the recognition area of the droplet 2, the droplet 1 is the main as shown in FIG. It is determined that the droplet is an unmerged droplet that is separated into a droplet and a sub-droplet.

  In this case, the set drive voltage value (1) is changed (S107), the processing from S102 is repeated again, and the droplets 1 and 2 are imaged again.

  At this time, the drive voltage value changed from the drive voltage value (1) varies depending on the environmental temperature, ink characteristics, and the like. For example, in the case shown in FIG. 15, the drive voltage value (1) is 14V−. When it is in the range of 15V (uncombined-merged area), the voltage value in the range of 13V-14V in which each image of the captured droplet 1 and droplet 2 becomes the merged-merged area is set. .

  As a result of re-imaging each of droplet 1 and droplet 2 through the process of S107, if it is determined No again in S105, the drive voltage value may be further changed and the process from S102 repeated. preferable.

  If the result of changing the drive voltage value (1) is “Yes” in S105, the droplet speed is calculated as described above in the subsequent process of S106.

  The voltage correction coefficient is obtained based on the droplet velocity when the droplet is ejected using at least two different drive voltage values and the drive voltage value at that time. Therefore, next, whether or not the droplet velocity is calculated using a different drive voltage value in addition to the drive voltage value (1) (including the changed drive voltage value if changed in the process of S107). Is determined (S108).

  Here, since only one driving voltage value is used and the droplet velocity is calculated, a driving voltage value (2) with a different driving voltage value is set (S109), and the processing from S101 is repeated. At this time, the drive voltage value (1) in S101 is replaced with the drive voltage value (2). As a result, a droplet is ejected again with a drive voltage value (2) different from the drive voltage value (1), and the droplet velocity is calculated through the same processing as described above.

  Once the droplet velocity is calculated using the two driving voltage values of the driving voltage value (1) and the driving voltage value (2), the calculated droplet velocity and each driving voltage value (1), Based on (2), the voltage correction coefficient α is calculated (S110).

This voltage correction coefficient α is obtained by setting the voltage value at the drive voltage value (1) (or the drive voltage value after the change if changed in the process of S107) to Vo ₁ and the drive voltage value (2) (in the above S107). When changed in the process, the voltage value at the changed drive voltage value) is Vo ₂ , the droplet velocity at the voltage value Vo ₁ is Ve ₁ , and the droplet velocity at the voltage value Vo ₂ is Ve ₂ . Then, the voltage correction coefficient α is calculated as follows.

Voltage correction coefficient α = (Vo ₁ −Vo ₂ ) / (Ve ₁ −Ve ₂ )

  For example, if the droplet velocity at a voltage value of 21V is 3.7 m / sec and the droplet velocity at a voltage value of 20V is 2.6 m / sec, the voltage correction coefficient α = (21−20) / (3. 7-2.6) = 0.91.

  The voltage correction coefficient α calculated in this way is stored in a predetermined area.

  In FIG. 5, the DPN correction process discharges a DPN correction droplet from each nozzle with a predetermined drive voltage value, obtains the droplet velocity at that time, and calculates and stores the voltage correction coefficient α calculated and stored above. The difference between the velocity of the droplets ejected from each nozzle and the target velocity is calculated, and a correction voltage value for eliminating the difference is calculated (S2).

  Here, when the correction voltage value is “Vo correction”, the current voltage value is “Vo current”, the droplet velocity target value is “Ve target”, and the current droplet velocity is “Ve current”, the correction voltage value is The “Vo correction” is calculated as follows.

  Vo correction = Vo current + (Ve target−Ve current) × α

  For example, the voltage value of “Vo present” is 21V, the droplet velocity of “Ve target” is 4.0 m / sec, the droplet velocity of “Ve present” is 3.7 m / sec, and the voltage correction coefficient α is When 0.91 is set, the correction voltage value “Vo correction” = 21 + (4.0-3.7) × 0.91 = 2.27V.

  Next, using the correction voltage value of each nozzle calculated in the process of S2, the droplet is ejected again, and the droplet velocity is redetected (S3). The re-detected droplet velocity is substituted into the above “Ve present”.

  Next, it is determined whether or not the droplet velocity detected in S3 has achieved the target velocity (S4). Here, it is only necessary that the detected droplet velocity is within an allowable range of the target velocity, for example, ± 2% of the target velocity.

  If not within the allowable range (No in S4), the process returns to S2. Here, the difference between the droplet velocity re-detected by the process of S2 and the target velocity is calculated, and a new correction voltage value is calculated so as to eliminate the difference. If it is within the allowable range (Yes in S4), the voltage correction process is completed and the process ends.

  The effects of the present invention are illustrated below by giving experimental examples. In each of the following experimental examples, the droplet velocity is detected by using the same driving voltage value in which the droplet 1 is separated into the main droplet and the sub-droplet, and the droplet 2 is combined. In this example, DPN correction is performed by calculating a voltage correction coefficient.

Experiment 1 (control example): When the droplet velocity is detected without changing the drive voltage value, and the DPN correction is performed by calculating the voltage correction coefficient Experiment 2 (the present invention): The drive voltage value is changed FIG. 8 and FIG. 9 show the experimental results when the droplet velocity is detected and the DPN correction is performed by calculating the voltage correction coefficient.

  FIG. 8 shows a case where the droplet velocity is detected without changing the drive voltage value in the inkjet head having 128 nozzles (Experiment 1: control example), and the droplet is changed by changing the drive voltage value. The graph which shows the sensitivity for every nozzle number when a speed is detected (Experiment 2: this invention) is shown. 8A shows the present invention of Experiment 2, and FIG. 8B shows a control example of Experiment 1. FIG.

  From the figure, the sensitivity detected from the droplet velocity calculated by re-imaging under the condition that the droplet is not separated into the main droplet and the sub-droplet by changing the drive voltage value is the drive voltage value. The variation is clearly smaller than the sensitivity detected from the droplet velocity calculated without changing the above.

  When the DPN correction is performed using the voltage correction coefficient calculated from the detected droplet velocity, as shown in FIG. 9, the DPN is calculated using the voltage correction coefficient calculated by changing the drive voltage value. When the correction is performed, there is clearly less variation in the droplet velocity discharged from each nozzle than when the DPN correction is performed using the voltage correction coefficient calculated without changing the drive voltage value. You can see that Although the number of corrections is one here, it can be seen that according to the present invention, the droplet velocity can be accurately stabilized in a short time with a small number of corrections.

  In the above description, when it is determined that the droplet 1 is separated into the main droplet and the sub-droplet when calculating the voltage correction coefficient α, the setting of the driving voltage value as the driving condition is driven. Although the voltage value (1) is changed to a different driving voltage value, the liquid droplets separated into the main liquid droplet and the sub liquid droplet after the discharge are combined into one liquid droplet before the liquid droplets are separated. It is also possible to change the interval time from the ejection to the first imaging timing, that is, the setting of the strobe delay time (1), so that the droplets 1 are combined and imaged.

  FIG. 10 shows a processing flow for calculating the voltage correction coefficient α in this mode.

  In advance, the setting input unit 300 of the computer 3 sets the strobe delay time (1) and the drive voltage value (1) (S201).

  Next, a droplet is ejected from an arbitrary nozzle according to the drive voltage value (1), and after the delay time set by the strobe delay time (1) has elapsed, the strobe 200 is caused to emit light and the CCD camera 201 images the droplet 1. The captured image is sent to the image processing unit 301.

  The image processing unit 301 determines a predetermined image recognition range from the transmitted image, recognizes an image having an image area equal to or larger than a predetermined threshold among images within the image recognition range, and recognizes the recognized image. Is an image of the droplet 1. After the image of the droplet 1 is determined, the position coordinate (X1, Y1) of the center of gravity is calculated from the area center of gravity (or volume center of gravity) of the droplet 1 (S202).

  Next, the flash body lay time (2) is set (S203), and after the delay time set by the flash body lay time (2) has elapsed, the flash 200 is caused to emit light again and the droplet 2 is imaged by the CCD camera 201. The captured image is sent to the image processing unit 301.

  The image processing unit 301 determines a predetermined image recognition range from the sent image, recognizes an image having an image area equal to or larger than a predetermined threshold among images within the image recognition range, and converts the recognized image into a liquid image. It is determined that the image is a droplet 2. After the image of the droplet 2 is determined, the position coordinates (X2, Y2) of the center of gravity are calculated from the area center of gravity (or volume center of gravity) of the droplet 2 (S204).

  Next, the recognition area of the droplet 1 obtained in S202 is compared with the recognition area of the droplet 2 obtained in S204 (S205). The processing up to this point is the same as the processing up to S105 in FIG.

  As a result of the comparison in S205, when it is determined Yes in S205, that is, when the recognition area of the droplet 1 exceeds, for example, 90% of the recognition area of the droplet 2, the droplet 1 and the droplet As shown in FIG. 7 (a), it is determined that No. 2 is not separated into main droplets and sub-droplets. Accordingly, the droplet velocity is calculated by the above formula using the position coordinates of the center of gravity of each of the droplets 1 and 2 and the strobody lay time (1) and the strobody lay time (2) (S206).

  If it is determined No in S205, that is, if the recognition area of the droplet 1 does not exceed 90% of the recognition area of the droplet 2, the droplet 1 is shown in FIG. In this way, it is determined that the droplet is an unmerged droplet separated into a main droplet and a sub-droplet.

  In this case, the set strobody lay time (1) is changed (S207), and the processing from S202 is repeated again to image the droplet 1 and the droplet 2 again.

  At this time, the strobody lay time changed from the strobody lay time (1) varies depending on the environmental temperature, ink characteristics, and the like, but in general, the droplets separated into the main droplet and the sub-droplet are merged with the flight. Therefore, the strobody lay time in which the delay time is changed larger than the strobody lay time (1) is set.

  As a result of re-imaging each of the droplet 1 and the droplet 2 through the processing of S207, if it becomes No again in S205, it is preferable to further change the strobodi time and repeat the processing from S202.

  If the result of changing the Strobody lay time (1) is Yes in S205, the droplet velocity is calculated as described above in the subsequent processing of S206.

  Next, it is determined whether or not the droplet velocity is calculated using a different drive voltage value in addition to the drive voltage value (1) (S208).

  Here, since the droplet velocity is only calculated with the drive voltage value (1), the drive voltage value (2) with a different drive voltage value is set (S209), and the processing from S201 is repeated. At this time, the drive voltage value (1) in S201 is replaced with the drive voltage value (2). As a result, a droplet is ejected again with a drive voltage value (2) different from the drive voltage value (1), and the droplet velocity is calculated through the same processing as described above.

  Once the droplet velocity is calculated from the drive voltage value (1) and the drive voltage value (2), respectively, the voltage correction coefficient is then calculated based on the calculated droplet velocity and each drive voltage value (1), (2). α is calculated (S210). The method for calculating the voltage correction coefficient α is as described above.

  As described above, when it is determined that the liquid droplet 1 is separated into the main liquid droplet and the sub liquid droplet, the setting of the strobody lay time (1) for imaging the liquid droplet 1 is changed to perform image capturing. By re-adjusting, the accurate positions of the centroids of the droplet 1 and the droplet 2 can be calculated, and the accurate droplet velocity can be detected. Similarly, the voltage correction coefficient α can be accurately set. As a result, the droplet velocity after DPN correction is less varied, and the droplet velocity can be accurately stabilized in a short time with a small number of corrections.

  When calculating the voltage correction coefficient α, if it is determined that the droplet 1 is separated into a main droplet and a sub-droplet, the position coordinates of the center of gravity of the droplet 1 are It is also possible to recalculate the calculated position coordinates of the center of gravity, and calculate the droplet velocity based on the recalculated position coordinates of the center of gravity.

  FIG. 11 shows a processing flow for calculating the voltage correction coefficient α in this mode.

  In advance, the setting input unit 300 of the computer 3 sets the strobe delay time (1) and the drive voltage value (1) (S301).

  Next, a droplet is ejected from an arbitrary nozzle according to the drive voltage value (1), and after the delay time set by the strobe delay time (1) has elapsed, the strobe 200 is caused to emit light and the CCD camera 201 images the droplet 1. The captured image is sent to the image processing unit 301.

  The image processing unit 301 determines a predetermined image recognition range from the sent image, and recognizes a droplet image in which the area of the droplet image is equal to or greater than a predetermined threshold among the droplet images within the image recognition range. Then, it is determined that the recognized droplet image is an image of the droplet 1. After the image of the droplet 1 is determined, the position coordinates (X1, Y1) of the center of gravity are calculated from the area center of gravity (or volume center of gravity) of the droplet 1 (S302).

  Next, the strobody lay time (2) is set (S303), and after the delay time set by the strobody lay time (2) has elapsed, the stroboscope 200 is caused to emit light again, and the CCD camera 201 images the droplet 2. The captured image is sent to the image processing unit 301.

  The image processing unit 301 determines a predetermined image recognition range from the sent image, and recognizes a droplet image in which the area of the droplet image is equal to or greater than a predetermined threshold among the droplet images within the image recognition range. Then, it is determined that the recognized droplet image is an image of the droplet 2. After the image of the droplet 2 is determined, the position coordinate (X2, Y2) of the center of gravity is calculated from the area center of gravity (or volume center of gravity) of the droplet 2 (S304).

  Next, the recognition area of the droplet 1 obtained in S302 is compared with the recognition area of the droplet 2 obtained in S304 (S305). The processing up to this point is the same as the processing up to S105 in FIG.

  As a result of the comparison in S305, when it is determined Yes in S305, that is, when the recognition area of the droplet 1 exceeds, for example, 90% of the recognition area of the droplet 2, the droplet 1 and the droplet As shown in FIG. 7 (a), it is determined that No. 2 is not separated into main droplets and sub-droplets. Accordingly, the droplet velocity is calculated by the above formula using the position coordinates of the center of gravity of each of the droplets 1 and 2 and the strobody lay time (1) and strobody lay time (2) (S306).

  Further, when it is determined No in S305, that is, when the recognition area of the droplet 1 does not exceed 90% of the recognition area of the droplet 2, the droplet 1 is shown in FIG. In this way, it is determined that the droplet is an unmerged droplet separated into a main droplet and a sub-droplet.

  As shown in FIG. 12, the captured target image of the liquid droplet is an image that falls within a frame of a predetermined image recognition range 800. Normally, the sub-droplet existing in the image recognition range 800 is regarded as a noise component and excluded by a predetermined threshold and is not recognized. However, here, in S305, the droplet 1 is the main droplet and the sub-droplet. If the image recognition condition is determined to be separated, all the droplet images (main droplets) in the image recognition range 800 are changed by changing the setting of the image recognition condition, canceling the threshold setting, or lowering the threshold level. And the sub-droplet) are calculated, the position of the area centroid (or volume centroid) is calculated from the recognized area, and this is set as the position coordinates (X1, Y1) of the correct centroid of the droplet 1 (S307). The correct position of the center of gravity is slightly closer to the sub-droplet than the position of the center of gravity of the main droplet.

  After calculating the center of gravity of the droplet 1 and the droplet 2 through the processing of S307, the position coordinates of the center of gravity of the droplet 1 and the position coordinates of the center of gravity of the droplet 2 and the strobody lay time ( Using 1) and the strobodilay time (2), the droplet velocity is calculated by the above formula (S306).

  Next, it is determined whether or not the droplet velocity is calculated using a different drive voltage value in addition to the drive voltage value (1) (S308).

  Here, since the droplet velocity is only calculated with the drive voltage value (1), the drive voltage value (2) with a different drive voltage value is set (S309), and the processing from S301 is repeated. At this time, the drive voltage value (1) in S301 is replaced with the drive voltage value (2). As a result, a droplet is ejected again with a drive voltage value (2) different from the drive voltage value (1), and the droplet velocity is calculated through the same processing as described above.

  Once the droplet velocity is calculated from the drive voltage value (1) and the drive voltage value (2), respectively, the voltage correction coefficient is then calculated based on the calculated droplet velocity and each drive voltage value (1), (2). α is calculated (S310). The method for calculating the voltage correction coefficient α is as described above.

  As described above, when it is determined that the droplet 1 is separated into the main droplet and the sub-droplet, the setting of the image recognition condition for recognizing the droplet 1 is changed to change the position of the center of gravity. Since accurate droplet velocity can be detected by recalculation, the voltage correction coefficient α can be accurately calculated in the same manner. As a result, the droplet velocity after DPN correction is less varied and less. The droplet velocity can be accurately stabilized in a short time by the number of corrections.

  In the above description, whether or not the droplet 1 is separated into the main droplet and the sub-droplet is determined by comparing the recognition area of the droplet 1 and the recognition area of the droplet 2. However, the present invention is not limited to this.

  For example, the area of the droplet in a state where the main droplet and the sub-droplet are combined is obtained and stored in advance, and the recognized area (main droplet and (If the sub-droplet is separated, the main droplet recognition area) is obtained, and then compared with the stored area of the combined droplets, the difference in area is a predetermined value. Whether or not (for example, whether or not the recognized area of the droplet 1 exceeds 90% of the stored area), and if it is determined that it is greater than or equal to a predetermined value (not exceeded), It may be determined that the droplet 1 is separated into a main droplet and a sub-droplet.

  An example of the calculation process flow of the voltage correction coefficient α in this case is shown in FIG.

  In advance, the setting input unit 300 of the computer 3 sets the strobe delay time (1) and the drive voltage value (1) (S401).

  Next, a droplet is ejected from an arbitrary nozzle according to the drive voltage value (1), and after the delay time set by the strobe delay time (1) has elapsed, the strobe 200 is caused to emit light and the CCD camera 201 images the droplet 1. The captured image is sent to the image processing unit 301.

  The image processing unit 301 determines a predetermined image recognition range from the sent image, and recognizes a droplet image in which the area of the droplet image is equal to or greater than a predetermined threshold among the droplet images within the image recognition range. Then, it is determined that the recognized droplet image is an image of the droplet 1. After the image of the droplet 1 is determined, the position coordinates (X1, Y1) of the center of gravity are calculated from the area center of gravity (or volume center of gravity) of the droplet 1 (S402).

  Next, the recognition area of the droplet 1 is compared with the area of the combined droplet stored in advance (S403).

  As a result of the comparison in S403, when it is determined as Yes, that is, when the recognized area of the droplet 1 exceeds, for example, 90% of the recognized area of the droplet 2, the droplet 1 is shown in FIG. ), It is determined that the main droplet and the sub-droplet are not separated.

  Further, when it is determined as No as a result of the comparison in S403, that is, when the recognized area of the droplet 1 does not exceed 90% of the recognized area of the droplet 2, for example, the droplet 1 is shown in FIG. As shown in b), it is determined that the droplet is an unmerged droplet separated into a main droplet and a sub-droplet.

  In this case, the set drive voltage value (1) is changed to a voltage value at which the droplet does not separate into the main droplet and the sub-droplet (S404), and the processing from S402 is repeated again, so that the droplet 1 is removed. Re-image.

  Next, the strobe delay time (2) is set (S405), and after the delay time set by the strobe delay time (2) has elapsed, the strobe 200 is caused to emit light again and the droplet 2 is imaged by the CCD camera 201. The captured image is sent to the image processing unit 301.

  The image processing unit 301 determines a predetermined image recognition range from the sent image, and recognizes a droplet image in which the area of the droplet image is equal to or greater than a predetermined threshold among the droplet images within the image recognition range. Then, it is determined that the recognized droplet image is an image of the droplet 2. At this time, since it is determined that the droplet 1 has not been separated into the main droplet and the sub-droplet, the droplet 2 is not separated into the main droplet and the sub-droplet. Can be estimated. After the image of the droplet 2 is determined, the position coordinate (X2, Y2) of the center of gravity is calculated from the area center of gravity (or volume center of gravity) of the droplet 2 (S406).

  After imaging the droplet 2, the droplet velocity is calculated as described above based on the position coordinates of the center of gravity of each of the droplets 1 and 2, the strobody lay time (1), and the strobody lay time (2) (S407). ).

  Next, it is determined whether or not the droplet velocity is calculated using a different drive voltage value in addition to the drive voltage value (1) (S408).

  Here, since only the droplet velocity is calculated with the drive voltage value (1), the drive voltage value (2) with a different drive voltage value is set (S409), and the processing from S401 is repeated. At this time, the drive voltage value (1) in S401 is replaced with the drive voltage value (2). As a result, a droplet is ejected again with a drive voltage value (2) different from the drive voltage value (1), and the droplet velocity is calculated through the same processing as described above.

  Once the droplet velocity is calculated from the drive voltage value (1) and the drive voltage value (2), respectively, the voltage correction coefficient is then calculated based on the calculated droplet velocity and each drive voltage value (1), (2). α is calculated (S410). The method for calculating the voltage correction coefficient α is as described above.

  Also in this aspect, when it is determined that the droplet 1 is separated into the main droplet and the sub-droplet, the drive voltage value is changed so that the droplet is not separated into the main droplet and the sub-droplet. In addition to the liquid droplets, the image pickup timing may be changed so that the liquid droplets are not separated into main liquid droplets and sub liquid droplets, and the image may be re-imaged. All droplet images existing within the image recognition range 800 including the sub-droplet (see FIG. 12) are recognized as the droplets, and the position coordinates of the center of gravity of the droplet 1 include the main droplet and the sub-droplet. Of course, it may be recalculated.

  Whether or not the droplet 1 is separated into a main droplet and a sub-droplet is determined from the beginning without setting a predetermined threshold value for determining a droplet during image processing, or lowering the threshold level. Thus, all the droplet images existing in the image recognition range 800 (see FIG. 12) when the image of the captured droplet 1 is processed are recognized as the droplets, and the droplets in the image recognition range 800 are recognized. When the number of images is counted and it is determined that the counted value is 2 or more, that is, a plurality of droplet images based on the image of the main droplet and the image of one or more sub-droplets exist, the droplet 1 May be determined as being separated into main droplets and sub-droplets.

  An example of a calculation processing flow of the voltage correction coefficient α when counting the number of images is shown in FIG.

  In advance, the setting input unit 300 of the computer 3 sets the strobe delay time (1) and the driving voltage value (1) (S501).

  Next, a droplet is ejected from an arbitrary nozzle according to the drive voltage value (1), and after the delay time set by the strobe delay time (1) has elapsed, the strobe 200 is caused to emit light and the CCD camera 201 images the droplet 1. The captured image is sent to the image processing unit 301.

  The image processing unit 301 determines a predetermined image recognition range from the sent image, and counts all droplet images within the image recognition range (S502). Here, a predetermined threshold value for determining a droplet at the time of image processing is not provided, and a droplet image that is within the image recognition range is not divided into a main droplet and a sub-droplet. The droplet image is recognized as a droplet.

  Therefore, it is determined whether or not the counted value of the counted droplet image is 2 or more (S503). If the count value is 2 or more, it is considered that the image captures a plurality of droplets, so that these droplets are separated into main droplets and one or more sub-droplets. It can be judged that.

  As a result, if it is determined in S503 that No (the count value is 1), the one droplet image is determined as the droplet 1, and the recognition area is calculated, and the center of gravity is calculated from the area centroid (or volume centroid). The position coordinates (X1, Y1) are calculated (S504).

  If it is determined in S503 that Yes (the count value is 2 or more), it is determined that all of the two or more droplet images including the sub-droplet are droplets 1 and the plurality of droplet images are recognized. The area is calculated, and the position coordinates (X1, Y1) of the entire center of gravity are calculated from the area center of gravity (or volume center of gravity) (S505).

  Next, the strobe delay time (2) is set (S506), and after the delay time set by the strobe delay time (2) has elapsed, the strobe 200 is caused to emit light again and the droplet 2 is imaged by the CCD camera 201. The captured image is sent to the image processing unit 301.

  The image processing unit 301 determines a predetermined image recognition range from the sent image, determines that the droplet image within the image recognition range is an image of the droplet 2, and calculates the recognition area. After the image of the droplet 2 is determined, the position coordinate (X2, Y2) of the center of gravity is calculated from the area center of gravity (or volume center of gravity) of the droplet 2 (S507).

  After imaging the droplet 2, the droplet velocity is calculated as described above based on the position coordinates of the gravity centers of the droplet 1 and the droplet 2, the strobody lay time (1), and the strobody lay time (2) (S508). ).

  Next, it is determined whether or not the droplet velocity is calculated using a different drive voltage value in addition to the drive voltage value (1) (S509).

  Here, since the droplet velocity is only calculated with the drive voltage value (1), the drive voltage value (2) with a different drive voltage value is set (S510), and the processing from S502 is repeated. Then, a droplet is ejected again with a drive voltage value (2) different from the drive voltage value (1), and the droplet velocity is calculated in the same manner as described above.

  Once the droplet velocity is calculated from the drive voltage value (1) and the drive voltage value (2), respectively, the voltage correction coefficient is then calculated based on the calculated droplet velocity and each drive voltage value (1), (2). α is calculated (S511). The method for calculating the voltage correction coefficient α is as described above.

  In this aspect, since it is not necessary to re-image, the calculation time of the voltage correction coefficient α can be shortened accordingly.

  Furthermore, in the above description, the droplet velocity is detected by imaging one droplet ejected from the nozzle twice. However, the present invention is not limited to this, and the predetermined velocity from the droplet ejection trigger is determined. The droplet velocity may be detected from a single image captured by imaging the droplet once after the elapsed time.

  In order to obtain a droplet image by one imaging, it is only necessary to set a strobody lay time (1) for imaging after a predetermined elapsed time from the droplet ejection trigger in the computer 3; ) Is not required. That is, the strobody lay time (1) is a time period in which the stroboscope 200 starts to emit light after a predetermined elapsed time from the droplet discharge trigger and the discharged droplet is imaged once.

  In this case, the voltage correction coefficient α is calculated by causing the strobe 200 to be generated after a predetermined elapsed time after the droplet discharge trigger in each of the processing flows of FIGS. 6, 10, 11, 13, and 14. It is sufficient to activate only the strobodies lay time (1) for imaging and omit imaging of the droplet 2.

  To determine whether or not the droplet is separated into a main droplet and a sub-droplet from the image of the droplet obtained by one imaging, the recognition area of the droplet 1 and the droplet 2 Since the comparison with the recognized area cannot be performed, in this case, the area of the droplet in a state where the main droplet and the sub-droplet are combined is obtained in advance, as in the processing for recognizing the droplet 1 in FIG. The image of the droplet obtained by one imaging is processed by image processing to recognize the area (if the droplet is separated into a main droplet and a sub-droplet, the sub-droplet is excluded by a threshold value. (The recognized area of the main droplet) is compared with the stored area of the combined droplets to determine whether or not the difference in area is equal to or greater than a predetermined value (e.g., liquid Whether or not the droplet recognition area exceeds 90% of the stored area), and is equal to or greater than a predetermined value (not exceeded) If it is determined, it is preferable to determine that the droplets are separated into a main droplet and the auxiliary liquid droplets.

  Similarly to the processing for recognizing the droplet 1 in FIG. 14, a predetermined threshold value for determining a droplet is not provided at the time of image processing of a droplet image obtained by one imaging, or By lowering the threshold level, all the droplet images existing in the image recognition range 800 (see FIG. 12) when the captured droplet image is processed are recognized as droplets, and the image recognition range 800 When the number of droplet images is counted and it is determined that the counted value is 2 or more, that is, there are a plurality of droplet images based on the image of the main droplet and the image of one or more sub-droplets. It is also preferable to determine that the droplet is separated into a main droplet and a sub-droplet.

  In addition, as shown in FIG. 16, when the same droplet discharged from the nozzle is imaged twice, both droplets are separated into main droplets and sub-droplets (uncombined-unassembled) There is a case. At this time, it is considered that there is no large error even if the droplet velocity is detected using only the imaged main droplets, but it cannot be said that the accurate droplet velocity is detected. For this reason, it is desirable that the droplet velocity can be accurately detected even in such an unmerged-unmerged case.

  In this case, similarly to the process for recognizing the droplet 1 in FIG. 13, the area of the droplet in a state where the main droplet and the sub-droplet are combined is obtained and stored in advance, and each obtained by imaging. The image of the obtained droplet is image-processed to obtain the recognition area (the recognition area of the main droplet if it is separated into the main droplet and the sub-droplet), and then it is stored in the above combination By comparing with the area of the liquid droplet in the state of being in the state, it is determined whether or not the difference in area is equal to or greater than a predetermined value (for example, whether the recognition area of the liquid droplet exceeds 90% of the stored area). However, when it is determined that the value is equal to or greater than (not exceeding) the predetermined value, it can be determined that the droplet is separated into a main droplet and a sub-droplet.

  Similarly to the processing for recognizing the droplet 1 in FIG. 14, a predetermined threshold value for determining a droplet is not provided at the time of image processing of a droplet image obtained by imaging, or a threshold value is set. By lowering the level, all of the droplet images existing in the image recognition range 800 (see FIG. 12) when image processing is performed on the captured droplet image are recognized as droplets. When the number of droplet images is counted and it is determined that the counted value is 2 or more, that is, there are a plurality of droplet images based on the image of the main droplet and the image of one or more sub-droplets, the It can also be determined that the droplet is separated into a main droplet and a sub-droplet.

  According to the processing flow of FIG. 13, since it is determined that the droplet 1 is not separated into the main droplet and the sub-droplet, the droplet 2 is imaged. Although it can be estimated that the liquid droplets are not separated into droplets, the process for determining whether or not the liquid droplets are separated into main droplets and sub-droplets as described above is the same as with the liquid droplets 1. You may make it carry out also with respect to the droplet 2. This determination process may be performed simultaneously on the droplet 1 and the droplet 2 after imaging the droplet 1 and the droplet 2.

  After determining that both droplet 1 and droplet 2 are unmerged droplets separated into main droplets and sub-droplets, the positions of the centers of gravity of droplets 1 and 2 are Calculation is based on the position of the center of gravity including the main droplet and the sub-droplet.

  In the processing flow shown in FIGS. 13 and 14, it is determined whether or not the droplet 1 is separated into a main droplet and a sub-droplet after the imaging of the droplet 1 is completed and before the imaging of the droplet 2. However, the determination of whether or not the droplet 1 is separated into the main droplet and the sub-droplet may be performed after the droplet 2 is imaged.

  In addition, when the same droplet ejected from the nozzle is imaged twice, in order to detect the droplet velocity more accurately when both droplets are uncombined and uncombined, the droplets are mainly used. The process of determining whether or not the liquid droplets are separated into sub-droplets is performed on the liquid droplets 1 and 2 at the same time after the liquid droplets 1 and 2 are imaged, and then the liquid droplet 1 The liquid droplets 2 and the liquid droplets 2 may be combined with the main liquid droplets and the sub-liquid droplets without being separated into the combined liquid droplets, and the imaging may be performed again by changing the driving conditions or the imaging timing.

  In the present invention, the apparatus and method for detecting the droplet velocity are not limited to those applied to calculate the voltage correction coefficient α when performing the DPN correction processing in the droplet discharge apparatus described above, The same applies to the detection of the droplet velocity.

  In the present invention, the driving conditions for ejecting droplets are not limited to the driving voltage values described above, and can be adjusted by the pulse width of the driving signal, the driving waveform shape, and the like. Accordingly, the change and correction of the drive condition are not limited to the change and correction of the drive voltage value, and the pulse width of the drive signal, the drive waveform shape, and the like may be changed and corrected.

  A program according to the present invention causes a computer to execute the functions of the processes described above.

  Furthermore, a recording medium according to the present invention stores the above program. Examples of the recording medium include a flexible disk, a CD-ROM, a DVD-ROM, and a flash memory, but are not limited to these as long as the program can be stored in a readable manner.

  The droplet discharge device according to the present invention is not limited to an ink jet printer, but a droplet discharge device that discharges minute droplets from nozzles, for example, application of an EL material of an organic EL display, application of a color filter material of a liquid crystal display, etc. The same can be applied to the manufacturing apparatus used in the above.

The figure which shows the structural example of the system which is an example of the droplet velocity detection apparatus which concerns on this invention. Block diagram of share mode piezo inkjet head Sectional view of actuator cut at right angles to channel flow direction Circuit diagram showing schematic configuration of DPN drive substrate 5 Process flow diagram showing DPN correction process Process flow diagram for calculating the voltage correction factor (A) (b) is a figure which shows the state of the droplet imaged twice, respectively Graph showing the voltage correction coefficient (experimental example) for each nozzle Graph showing droplet velocity (experimental example) for each nozzle after DPN correction processing Process flow diagram for calculating the voltage correction factor Process flow diagram for calculating the voltage correction coefficient The figure which shows the position of the image recognition range and the center of gravity of the droplet Process flow diagram for calculating the voltage correction factor Process flow diagram for calculating the voltage correction coefficient The figure which shows the state of the discharged droplet for every drive voltage value Graph showing calculation results of conventional voltage correction coefficient

Explanation of symbols

1: Inkjet head 100: PZT substrate 101: Channel 102: Channel wall 103: Actuator 104: Cover plate 105: Nozzle 106: Nozzle plate 107: Common ink supply chamber 108: Wiring section 109: Electrode 2: Droplet detection section 200: Strobe 201: CCD camera 3: PC (computer)
300: Setting input unit 301: Image processing unit 4: Data control board 5: DPN drive board 500: Drive waveform creation part 501: Drive signal output part 502: FET element 6: Drive waveform generator 7: Drive voltage control part 700: D / A converter 701: Amplifier 8: Power supply 9: Offset power supply 800: Image recognition range

Claims (29)

A head for generating droplet discharge energy for discharging droplets from a plurality of nozzles;
Driving means for driving the head based on a predetermined driving voltage value and discharging droplets from the nozzle;
By driving the driving means to eject droplets from the nozzles, imaging the droplets ejected from the same nozzle twice at different imaging timings, and recognizing the captured droplets as images, A droplet velocity detecting means for detecting a droplet velocity from a droplet position coordinate and an interval time of each imaging timing;
A voltage correction coefficient creating means for detecting a droplet speed by the droplet speed detecting means and creating a voltage correction coefficient based on a relationship between the detected droplet speed and a driving voltage value at that time;
The droplet velocity detected by the droplet velocity detection means is compared with the target velocity, and the droplet velocity detected by the droplet velocity detection means and the voltage correction coefficient are set so that the droplet velocity becomes the target velocity. calculating a new driving voltage by using the voltage correction coefficient generated by the generating means, the predetermined drive voltage possess the speed adjustment means for changing to the new drive voltage,
Droplet ejection in which the droplet velocity is detected by the droplet velocity detection means, the voltage correction coefficient is created by the voltage correction coefficient creation means, and a new drive voltage value is changed by the velocity adjustment means for each nozzle. In the device
When the voltage correction coefficient is created by the voltage correction coefficient creating means, the droplet velocity detecting means is configured to make at least one of the droplets imaged twice at the different imaging timings as a main droplet and a sub-liquid. It is determined whether or not the droplets are separated, and when it is determined that the droplets are separated, the predetermined drive voltage value is changed to a voltage value at which the droplets are not separated into main droplets and sub-droplets. to, again, have a row the detection of droplet velocity,
The droplet discharge device , wherein the droplet velocity detection means detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value . A head for generating droplet discharge energy for discharging droplets from a plurality of nozzles;
Driving means for driving the head based on a predetermined driving voltage value and discharging droplets from the nozzle;
By driving the driving means to eject droplets from the nozzles, imaging the droplets ejected from the same nozzle twice at different imaging timings, and recognizing the captured droplets as images, A droplet velocity detecting means for detecting a droplet velocity from a droplet position coordinate and an interval time of each imaging timing;
A voltage correction coefficient creating means for detecting a droplet speed by the droplet speed detecting means and creating a voltage correction coefficient based on a relationship between the detected droplet speed and a driving voltage value at that time;
The droplet velocity detected by the droplet velocity detection means is compared with the target velocity, and the droplet velocity detected by the droplet velocity detection means and the voltage correction coefficient are set so that the droplet velocity becomes the target velocity. Speed adjustment means for calculating a new drive voltage value using the voltage correction coefficient created by the creation means and changing the predetermined drive voltage value to the new drive voltage value ;
Droplet ejection in which the droplet velocity is detected by the droplet velocity detection means, the voltage correction coefficient is created by the voltage correction coefficient creation means, and a new drive voltage value is changed by the velocity adjustment means for each nozzle. In the device
When the voltage correction coefficient is created by the voltage correction coefficient creating means, the droplet velocity detecting means is configured to make at least one of the droplets imaged twice at the different imaging timings as a main droplet and a sub-liquid. It is determined whether or not the liquid droplets are separated, and when it is determined that the liquid droplets are separated, the imaging timing is changed to a timing at which the liquid droplets are not separated into main liquid droplets and sub liquid droplets, and , Detect droplet velocity ,
The droplet discharge device, wherein the droplet velocity detection means detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value. A head for generating droplet discharge energy for discharging droplets from a plurality of nozzles;
Driving means for generating a droplet discharge trigger based on a predetermined drive voltage value and driving the head to discharge a droplet from a nozzle;
By driving the driving means to eject droplets from the nozzle, imaging the droplets ejected from the nozzle, and recognizing the imaged droplets, the position coordinates of the droplets and the droplet ejection A droplet velocity detecting means for detecting a droplet velocity from an interval time from a trigger to imaging;
A voltage correction coefficient creating means for detecting a droplet speed by the droplet speed detecting means and creating a voltage correction coefficient based on a relationship between the detected droplet speed and a driving voltage value at that time;
The droplet velocity detected by the droplet velocity detection means is compared with the target velocity, and the droplet velocity detected by the droplet velocity detection means and the voltage correction coefficient are set so that the droplet velocity becomes the target velocity. Speed adjustment means for calculating a new drive voltage value using the voltage correction coefficient created by the creation means and changing the predetermined drive voltage value to the new drive voltage value ;
Droplet ejection in which the droplet velocity is detected by the droplet velocity detection means, the voltage correction coefficient is created by the voltage correction coefficient creation means, and a new drive voltage value is changed by the velocity adjustment means for each nozzle. In the device
The droplet velocity detection means determines whether or not the imaged droplet is separated into a main droplet and a sub-droplet when the voltage correction coefficient is created by the voltage correction coefficient creation means. The predetermined drive voltage value is changed to a voltage value at which the droplet does not separate into a main droplet and a sub-droplet, and the droplet velocity is detected again ,
The droplet discharge device , wherein the droplet velocity detection means detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value . A head for generating droplet discharge energy for discharging droplets from a plurality of nozzles;
Driving means for generating a droplet discharge trigger based on a predetermined drive voltage value and driving the head to discharge a droplet from a nozzle;
By driving the driving means to eject droplets from the nozzle, imaging the droplets ejected from the nozzle, and recognizing the imaged droplets, the position coordinates of the droplets and the droplet ejection A droplet velocity detecting means for detecting a droplet velocity from an interval time from a trigger to imaging;
A voltage correction coefficient creating means for detecting a droplet speed by the droplet speed detecting means and creating a voltage correction coefficient based on a relationship between the detected droplet speed and a driving voltage value at that time;
The droplet velocity detected by the droplet velocity detection means is compared with the target velocity, and the droplet velocity detected by the droplet velocity detection means and the voltage correction coefficient are set so that the droplet velocity becomes the target velocity. Speed adjustment means for calculating a new drive voltage value using the voltage correction coefficient created by the creation means and changing the predetermined drive voltage value to the new drive voltage value ;
Droplet ejection in which the droplet velocity is detected by the droplet velocity detection means, the voltage correction coefficient is created by the voltage correction coefficient creation means, and a new drive voltage value is changed by the velocity adjustment means for each nozzle. In the device
The droplet velocity detection means determines whether or not the imaged droplet is separated into a main droplet and a sub-droplet when the voltage correction coefficient is created by the voltage correction coefficient creation means. If it is determined, the interval time from the droplet discharge trigger to imaging is changed to an interval time at which the droplet does not separate into the main droplet and the sub-droplet, and the droplet velocity is detected again. Yes,
The droplet discharge device , wherein the droplet velocity detection means detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value .   The droplet velocity detection means recognizes an image having a recognition area equal to or larger than a predetermined area when an image of the captured droplet is recognized as a droplet, and images the first and second droplets. It is determined whether or not the difference in area from the liquid droplet is greater than or equal to a predetermined value. The droplet discharge device according to claim 1, wherein the droplet discharge device is determined to be.   The droplet velocity detection means recognizes an image whose recognition area when a captured droplet is recognized as an image is a predetermined area or more, and recognizes the recognized area of the captured droplet as a main memory previously stored. It is determined whether or not the difference between the combined area of the droplet and the sub-droplet is greater than or equal to a predetermined value, and if it is determined that the difference is greater than or equal to the predetermined value, the droplet is the main droplet and sub-droplet The droplet discharge device according to claim 1, wherein the droplet discharge device is determined to be separated from each other.   The droplet velocity detection means recognizes all of the captured droplet images within the image recognition range as droplets, counts the number of droplet images within the image recognition range, and the count value is 2 or more. 5. The droplet discharge device according to claim 1, wherein, when determined, the droplet is determined to be separated into a main droplet and a sub-droplet. Each droplet is ejected from a nozzle with a predetermined drive voltage value, the droplet ejected from the same nozzle is imaged twice at different imaging timings, and each captured droplet is recognized as an image. Detecting a droplet velocity from the position coordinates of each and the interval time of each imaging timing;
Detecting a discharged droplet velocity to create a voltage correction coefficient based on a relationship between the droplet velocity and a driving voltage value at that time;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. was closed and a step of changing to the new drive voltage,
In the droplet velocity adjusting method , wherein the step of detecting the droplet velocity, the step of creating the voltage correction coefficient, and the step of changing to the new drive voltage value are performed for each of a plurality of nozzles .
The step of creating the voltage correction coefficient includes separating at least one of the droplets imaged twice at the different imaging timings into a main droplet and a sub-droplet when detecting a droplet velocity. And if it is determined that the head is separated, the predetermined drive voltage value of the head is changed to a voltage value at which the droplet does not separate into a main droplet and a sub-droplet. , Again detect the droplet velocity ,
The method of adjusting a droplet speed, wherein the step of detecting the droplet velocity detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value . Each droplet is ejected from a nozzle with a predetermined drive voltage value, the droplet ejected from the same nozzle is imaged twice at different imaging timings, and each captured droplet is recognized as an image. Detecting a droplet velocity from the position coordinates of each and the interval time of each imaging timing;
Detecting a discharged droplet velocity to create a voltage correction coefficient based on a relationship between the droplet velocity and a driving voltage value at that time;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. was closed and a step of changing to the new drive voltage,
In the droplet velocity adjusting method , wherein the step of detecting the droplet velocity, the step of creating the voltage correction coefficient, and the step of changing to the new drive voltage value are performed for each of a plurality of nozzles .
The step of creating the voltage correction coefficient includes separating at least one of the droplets imaged twice at the different imaging timings into a main droplet and a sub-droplet when detecting a droplet velocity. If it is determined that the droplets are separated, the imaging timing is changed to a timing at which the droplets are not separated into main droplets and sub-droplets, and the droplet velocity is changed again. It performs detection,
The method of adjusting a droplet speed, wherein the step of detecting the droplet velocity detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value . By generating a droplet discharge trigger at a predetermined drive voltage value, discharging a droplet from the nozzle, imaging the droplet discharged from the nozzle, and recognizing the image of the captured droplet, Detecting a droplet velocity from a position coordinate and an interval time from the droplet discharge trigger to imaging;
Detecting a discharged droplet velocity to create a voltage correction coefficient based on a relationship between the droplet velocity and a driving voltage value at that time;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. was closed and a step of changing to the new drive voltage,
In the droplet velocity adjusting method , wherein the step of detecting the droplet velocity, the step of creating the voltage correction coefficient, and the step of changing to the new drive voltage value are performed for each of a plurality of nozzles .
In the step of creating the voltage correction coefficient, it is determined whether or not the droplet imaged at the time of detecting the droplet velocity is separated into a main droplet and a sub-droplet. In addition, the predetermined driving voltage value of the head is changed to a voltage value at which the droplet does not separate into a main droplet and a sub-droplet, and the droplet velocity is detected again ,
The method of adjusting a droplet speed, wherein the step of detecting the droplet velocity detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value . By generating a droplet discharge trigger at a predetermined drive voltage value, discharging a droplet from the nozzle, imaging the droplet discharged from the nozzle, and recognizing the image of the captured droplet, Detecting a droplet velocity from a position coordinate and an interval time from the droplet discharge trigger to imaging;
Detecting a discharged droplet velocity to create a voltage correction coefficient based on a relationship between the droplet velocity and a driving voltage value at that time;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. was closed and a step of changing to the new drive voltage,
In the droplet velocity adjusting method , wherein the step of detecting the droplet velocity, the step of creating the voltage correction coefficient, and the step of changing to the new drive voltage value are performed for each of a plurality of nozzles .
In the step of creating the voltage correction coefficient, it is determined whether or not the droplet imaged at the time of detecting the droplet velocity is separated into a main droplet and a sub-droplet. In addition, the interval time from the droplet discharge trigger to imaging is changed to an interval time in which the droplet does not separate into a main droplet and a sub-droplet, and the droplet velocity is detected again,
The method of adjusting a droplet speed, wherein the step of detecting the droplet velocity detects the droplet velocity even after adjusting the droplet velocity by changing to the new drive voltage value . The step of creating the voltage correction coefficient recognizes an image having a recognition area equal to or larger than a predetermined area when the imaged droplet is recognized as a droplet, and the first imaged droplet and the second time It is determined whether or not the difference in area from the imaged droplet is greater than or equal to a predetermined value, and if it is determined that the difference is greater than or equal to the predetermined value, any of the droplets becomes a main droplet and a sub-droplet. 10. The droplet speed adjusting method according to claim 8, wherein it is determined that the droplets are separated. In the step of creating the voltage correction coefficient, an image whose recognition area when the captured droplet is recognized is recognized as a droplet, and the recognized area of the captured droplet is stored in advance. It is determined whether or not the difference between the combined area of the main droplet and the sub-droplet is equal to or greater than a predetermined value. It is judged that it has isolate | separated into the droplet, The droplet speed adjustment method in any one of Claims 8-11 characterized by the above-mentioned. The step of creating the voltage correction coefficient recognizes all the captured droplet images within the image recognition range as droplets, counts the number of droplet images within the image recognition range, and the count value is 2 or more. 12. The droplet speed adjusting method according to claim 8 , wherein when it is determined that there is a droplet, it is determined that the droplet is separated into a main droplet and a sub-droplet. The liquid droplets ejected from the same nozzle based on a predetermined drive voltage value are imaged twice at different imaging timings, and each captured liquid droplet is image-recognized, whereby the position coordinates of each liquid droplet and each of the liquid droplets are recognized. In the droplet velocity detection device that detects the droplet velocity from the interval time of the imaging timing of
A determination means for determining whether at least one of the captured droplets is separated into a main droplet and a sub-droplet;
Control that detects the droplet velocity again by changing the imaging timing to a timing at which the droplet does not separate into a main droplet and a sub-droplet when the determination unit determines that the droplet is separated. Means for detecting a droplet velocity. By imaging a droplet ejected from a nozzle by a droplet ejection trigger generated based on a predetermined driving voltage value and recognizing the captured droplet, the position coordinates of the droplet and the droplet ejection In a droplet velocity detection device that detects a droplet velocity from an interval time from a trigger to imaging,
Determining means for determining whether or not the imaged droplet is separated into a main droplet and a sub-droplet;
When it is determined by the determination means that the separation is performed, the interval time from the droplet discharge trigger to imaging is changed to an interval time at which the droplet is not separated into the main droplet and the sub-droplet, and again And a droplet velocity detection apparatus comprising a control means for detecting the droplet velocity. The determination means recognizes an image having a recognition area of a predetermined area or more when the captured droplet is recognized as a droplet, and at the same time, the first captured droplet and the second captured droplet. And whether or not the difference in area is greater than or equal to a predetermined value, and if it is determined that the difference is greater than or equal to a predetermined value, any of the droplets is separated into a main droplet and a sub-droplet The droplet velocity detection device according to claim 15 , wherein the determination is made. The determination means recognizes an image whose recognized area when a captured droplet is recognized as an image is a predetermined area or more, and recognizes the recognized area of the captured droplet and a main droplet stored in advance. It is determined whether or not the difference between the combined area of the sub-droplet and the area is greater than or equal to a predetermined value, and when it is determined that the difference is greater than or equal to the predetermined value, the liquid droplet is separated into a main droplet and a sub-droplet The droplet velocity detection device according to claim 15 or 16 , wherein the droplet velocity detection device determines that the droplet velocity is detected. The determination means recognizes all the captured droplet images within the image recognition range as droplets, counts the number of droplet images within the image recognition range, and determines that the count value is 2 or more. case, the droplet speed detecting apparatus according to claim 15 or 16, wherein the determining the droplet is separated into a main droplet and the auxiliary liquid droplets. The liquid droplets ejected from the same nozzle based on a predetermined drive voltage value are imaged twice at different imaging timings, and each captured liquid droplet is image-recognized, whereby the position coordinates of each liquid droplet and each of the liquid droplets are recognized. In the droplet velocity detection method for detecting the droplet velocity from the interval time of the imaging timing of
It is determined whether or not at least one of the imaged droplets is separated into a main droplet and a sub-droplet. A droplet velocity detection method, wherein the droplet velocity is detected again after changing to a timing at which the droplets and sub-droplets are not separated. By imaging a droplet ejected from a nozzle by a droplet ejection trigger generated based on a predetermined drive voltage value and recognizing the captured droplet, the position coordinates of the droplet and the droplet ejection In a droplet velocity detection method for detecting a droplet velocity from an interval time from a trigger to imaging,
It is determined whether or not the imaged droplet is separated into a main droplet and a sub-droplet. If it is determined that the droplet is separated, an interval time from the droplet discharge trigger to imaging is determined as the liquid droplet. A droplet velocity detection method, wherein the droplet velocity is detected again after changing to an interval time during which the droplet does not separate into a main droplet and a sub-droplet. An image in which the recognized area when the captured droplet is recognized is recognized as a droplet, and the difference in area between the first captured droplet and the second captured droplet Is determined to be greater than or equal to a predetermined value, and if it is determined to be greater than or equal to a predetermined value, it is determined that any droplet is separated into a main droplet and a sub-droplet. The droplet velocity detection method according to claim 20 . Recognize an image whose recognition area when the captured droplet is recognized as a predetermined area or more as a droplet, and recognize the recognized area of the captured droplet and the main and sub-droplets stored in advance. It is determined whether or not the difference from the combined area is greater than or equal to a predetermined value, and if it is determined that the difference is greater than or equal to a predetermined value, it is determined that the droplet is separated into a main droplet and a sub-droplet The droplet velocity detection method according to claim 20 or 21, wherein: When all of the captured droplet images within the image recognition range are recognized as droplets, the number of droplet images within the image recognition range is counted, and when it is determined that the counted value is 2 or more, the liquid image The droplet velocity detection method according to claim 20 or 21, wherein it is determined that the droplet is separated into a main droplet and a sub-droplet. On the computer,
Each droplet is ejected from a nozzle with a predetermined drive voltage value, the droplet ejected from the same nozzle is imaged twice at different imaging timings, and each captured droplet is recognized as an image. the position coordinates of the the interval time of each imaging timing and ability to detect the drop velocity from
A function of creating a voltage correction coefficient based on the relationship between the droplet velocity and the driving voltage value at that time by detecting the ejected droplet velocity;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. the and a function to change the new drive voltage,
Realizing the function of detecting the droplet velocity, the function of creating the voltage correction coefficient, and the function of changing to the new drive voltage value for each of a plurality of nozzles ,
The function of creating the voltage correction coefficient is to separate at least one of the droplets imaged twice at the different imaging timings when detecting the droplet velocity into a main droplet and a sub-droplet. And if it is determined that the head is separated, the predetermined drive voltage value of the head is changed to a voltage value at which the droplet does not separate into a main droplet and a sub-droplet. Realize the function to detect the droplet velocity again ,
The solution function of detecting the drop speed, the program characterized by Rukoto to realize the function of detecting the drop velocity even after the change to the new drive voltage value to adjust the drop velocity. On the computer,
Each droplet is ejected from a nozzle with a predetermined drive voltage value, the droplet ejected from the same nozzle is imaged twice at different imaging timings, and each captured droplet is recognized as an image. A function of detecting the droplet velocity from the position coordinates of each and the interval time of each imaging timing,
A function of creating a voltage correction coefficient based on the relationship between the droplet velocity and the driving voltage value at that time by detecting the ejected droplet velocity;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. the and a function to change the new drive voltage,
Realizing the function of detecting the droplet velocity, the function of creating the voltage correction coefficient, and the function of changing to the new drive voltage value for each of a plurality of nozzles ,
The function of creating the voltage correction coefficient is to separate at least one of the droplets imaged twice at the different imaging timings when detecting the droplet velocity into a main droplet and a sub-droplet. If it is determined that the droplets are separated, the imaging timing is changed to a timing at which the droplets are not separated into main droplets and sub-droplets, and the droplet velocity is changed again. Realize the function to detect ,
The solution function of detecting the drop speed, the program characterized by Rukoto to realize the function of detecting the drop velocity even after the change to the new drive voltage value to adjust the drop velocity. On the computer,
By generating a droplet discharge trigger at a predetermined drive voltage value, discharging a droplet from the nozzle, imaging the droplet discharged from the nozzle, and recognizing the image of the captured droplet, A function of detecting a droplet velocity from a position coordinate and an interval time from the droplet discharge trigger to imaging;
A function of creating a voltage correction coefficient based on the relationship between the droplet velocity and the driving voltage value at that time by detecting the ejected droplet velocity;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. the and a function to change the new drive voltage,
Realizing the function of detecting the droplet velocity, the function of creating the voltage correction coefficient, and the function of changing to the new drive voltage value for each of a plurality of nozzles ,
The function of creating the voltage correction coefficient is to determine whether or not the droplet imaged at the time of detecting the droplet velocity is separated into a main droplet and a sub-droplet. In addition, the predetermined drive voltage value of the head is changed to a voltage value at which the droplet is not separated into a main droplet and a sub-droplet, and a function of detecting a droplet velocity is realized again .
The solution function of detecting the drop speed, the program characterized by Rukoto to realize the function of detecting the drop velocity even after the change to the new drive voltage value to adjust the drop velocity. On the computer,
By generating a droplet discharge trigger at a predetermined drive voltage value, discharging a droplet from the nozzle, imaging the droplet discharged from the nozzle, and recognizing the image of the captured droplet, A function of detecting a droplet velocity from a position coordinate and an interval time from the droplet discharge trigger to imaging;
A function of creating a voltage correction coefficient based on the relationship between the droplet velocity and the driving voltage value at that time by detecting the ejected droplet velocity;
A new driving voltage value is calculated using the detected droplet velocity and the created voltage correction coefficient so that the droplet velocity discharged from the nozzle becomes a target velocity, and the predetermined driving voltage value is calculated. the and a function to change the new drive voltage,
Realizing the function of detecting the droplet velocity, the function of creating the voltage correction coefficient, and the function of changing to the new drive voltage value for each of a plurality of nozzles ,
The function of creating the voltage correction coefficient is to determine whether or not the droplet imaged at the time of detecting the droplet velocity is separated into a main droplet and a sub-droplet. In addition, the interval time from the droplet discharge trigger to imaging is changed to an interval time in which the droplet is not separated into the main droplet and the sub-droplet, and the function of detecting the droplet velocity is realized again.
The solution function of detecting the drop speed, the program characterized by Rukoto to realize the function of detecting the drop velocity even after the change to the new drive voltage value to adjust the drop velocity. A recording medium storing the program according to any one of claims 25 to 28 .

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