JP2009098117A - Liquid droplet measuring apparatus and liquid droplet measurement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately measure the volume, speed, and position of a droplet, by making a liquid droplet irradiated by adjusting the light intensity distribution of the beam cross-section of laser light. <P>SOLUTION: A liquid droplet measuring apparatus is constituted of a first laser light source; a first optical means which makes, in terms of a beam cross-section of the laser light, beam width in a direction perpendicular to the direction of ejection of liquid droplets, being larger than the beam width in the direction of ejection of the liquid droplets, and makes the light intensity of the laser light fall within a prescribed range, where variation in an ejection position of the liquid droplets occurs in the direction perpendicular to the direction of ejection of the liquid droplet, at a position where the laser light from the first laser light source is irradiated to the liquid droplets ejected; a first light-receiving means which receives the laser light that has been irradiated to the liquid droplet by the first optical means and generates a detection signal; and a first liquid droplet characteristics calculating means which calculates the volume of the liquid droplets and the velocity of the liquid droplets, from the detection signal generated by the first light-receiving device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a droplet measuring device and a droplet measuring method, and more particularly to a droplet measuring device and a droplet measuring device for measuring the volume, velocity, and position of a droplet discharged from a print head of a recording apparatus such as an ink jet printer. Regarding the method.

  Conventionally, patent documents disclose the following inventions as methods and apparatuses for measuring the volume, velocity, and position of droplets ejected from a print head.

  In Patent Document 1, a laser beam is irradiated onto a droplet, and the laser beam after passing through the droplet is incident on a detection unit through a slit. Based on a change in an output signal from the detection unit, A method and apparatus for measuring velocity and position is disclosed.

  In Patent Document 2, a plurality of laser beams are irradiated in a direction perpendicular to the droplet discharge direction, and droplets are ejected between the plurality of laser beams, or droplets are crossed across the plurality of laser beams. A method and apparatus for measuring the volume, velocity, and position of a droplet by ejecting a liquid is disclosed.

Specifically, a droplet is ejected between a pair of laser beams, and when a droplet is detected in any of the beams, it is detected that the droplet is bent and ejected. And the method of calculating | requiring a bending amount and drop volume (outer shape) by changing the space | interval of a laser beam little by little is disclosed. Further, as an example in which the interval between laser beams is not changed, a method for determining whether the amount of bending is large depending on whether the amount of received laser light is large is disclosed.
JP 2006-281714 A JP 2005-83769 A

  However, the light intensity is not uniform in the beam cross section of the laser light, and there is a light intensity distribution in which the light intensity decreases from the center of the cross section toward the outside.

  Therefore, in Patent Documents 1 and 2, when such a light intensity distribution is prominent, the measurement results in the detection means vary, and the characteristics such as the volume, velocity, and position of the droplet are accurately measured. I can't. In Patent Document 2, in order to measure the volume, it is necessary to finely adjust the position of the light beam, which requires time and labor.

  Patent Document 2 discloses that when the change in the amount of received laser light is large without changing the interval of the laser light, it is determined that the amount of bending is large, but there is no detailed description of the determination method.

  Further, in Patent Document 1, since a slit is used in the optical path to obtain a droplet passage signal, it is necessary to make the light quantity distribution of the light entering the slit uniform. If there is a light quantity distribution, it will appear as an error in the timing detection that passed through the slit. In addition, in order to measure droplets (especially measurement of the passage position of droplets) with an inkjet head, it is necessary to measure the distance at which the paper is actually placed, which is generally 0.5 to 2 mm. There is no disclosure of a method for making the light quantity uniform distribution at such close positions. Furthermore, the amount of light incident on the sensor is reduced by the amount of light emitted from the slit, and the sensor output is reduced. Therefore, it is difficult to increase the S / N ratio of the signal. On the other hand, when the width of the slit is increased, the amount of incident light is increased and the S / N ratio of the signal is improved. However, in the method of Patent Document 1, the accuracy of detecting the passage of a droplet is lowered.

  The present invention has been made in view of such circumstances, and a droplet capable of accurately measuring the characteristics of the droplet by adjusting the light intensity distribution of the beam cross section of the laser light and irradiating the droplet. An object of the present invention is to provide a measuring apparatus and a droplet measuring method.

  In order to achieve the above object, according to a first aspect of the present invention, in the droplet measuring apparatus, the first laser light source and the position where the laser beam from the first laser light source is irradiated to the discharged droplet are The beam cross section of the laser beam has a beam width in a direction perpendicular to the droplet discharge direction with respect to the beam width in the droplet discharge direction, and is perpendicular to the droplet discharge direction. First optical means for keeping the light intensity of the laser light within a predetermined range within a range in which variations in the ejection positions of the droplets in various directions occur, and the laser irradiated on the droplets by the first optical means A first light receiving unit that receives light and generates a detection signal; and a first droplet characteristic calculation unit that calculates a volume and a velocity of the droplet from the detection signal generated by the first light receiving unit. It is characterized by.

  According to the present invention, since the light intensity of the laser beam falls within a predetermined range within the range where the variation of the droplet ejection position occurs in the direction perpendicular to the droplet ejection direction by the first optical means, the droplet flight The volume and velocity of the droplet can be accurately measured without being affected by variations in the droplet ejection position caused by bending.

  In order to achieve the above object, the invention according to claim 2 is the droplet measuring apparatus according to claim 1, characterized in that the first optical means includes a cylindrical lens.

  According to the present invention, the light intensity of the laser light is kept within a predetermined range within the range in which the droplet discharge position varies in the direction perpendicular to the droplet discharge direction by the cylindrical lens. The volume and speed of the droplet can be accurately measured without being affected by variations in the discharge position of the generated droplet.

  In order to achieve the above object, the invention according to claim 3 is the droplet measuring apparatus according to claim 1, wherein the first optical means includes a diffusion plate for diffusing the laser beam.

  According to the present invention, it is possible to make the light intensity of the beam cross section of the laser beam irradiated to the droplet by diffusing the laser beam with the diffusion plate uniform, and the droplet discharge position caused by the flying curve of the droplet It is possible to accurately measure the volume and velocity of the droplets without being affected by variations in the above.

  In order to achieve the above object, the invention according to claim 4 is the droplet measuring device according to claim 1, wherein the first optical means includes a fly-eye lens that diffuses the laser light.

  According to the present invention, it is possible to make the light intensity of the beam cross-section of the laser beam irradiated to the droplet by diffusing the laser beam with the fly-eye lens, and to discharge the droplet caused by the flying curve of the droplet. The volume and velocity of the droplet can be accurately measured without being affected by variations in position.

  In order to achieve the above object, the invention according to claim 5 is the liquid droplet measuring apparatus according to any one of claims 1 to 4, wherein the second laser light source and the second laser light source for the discharged liquid droplets are used. At the position where the laser beam is irradiated, the light intensity of the laser beam is reduced within the range in which the droplet discharge position varies in the direction perpendicular to the droplet discharge direction with respect to the laser beam cross section. The second optical means for making uniform, the second light receiving means for receiving the laser light applied to the droplet by the second optical means and generating a detection signal, and the generated by the second light receiving means And a second droplet characteristic calculating means for calculating the position of the droplet from the detection signal.

  According to the present invention, the second optical means makes the light intensity of the laser light non-uniform within a range in which variations in the droplet discharge position occur in the direction perpendicular to the droplet discharge direction. It can be measured accurately. The volume, velocity and position of the droplet can be measured simultaneously.

  In order to achieve the above object, the invention according to claim 6 is the droplet measuring apparatus according to any one of claims 1 to 5, wherein the laser beam received by the first light receiving means or the second light receiving means is limited. It has the light limiting means to do.

  According to the present invention, the volume, velocity, and position of a droplet can be measured with high accuracy.

  In order to achieve the above object, the invention according to claim 7 is the droplet measuring apparatus according to any one of claims 1 to 6, wherein the color of the laser light emitted from the first laser light source or the second laser light source. The color of the laser light emitted from the above is a complementary color to the color of the droplet.

  According to the present invention, the volume and velocity of a droplet can be measured with high accuracy.

  In order to achieve the above object, the invention according to claim 8 is the droplet measuring apparatus according to claim 5, wherein the laser light emitted from the first laser light source and the laser light emitted from the second laser light source are: The wavelength is different.

  According to the present invention, it is possible to more reliably measure the volume, velocity and position of a droplet simultaneously.

  In order to achieve the above object, the invention according to claim 9 is the droplet measuring apparatus according to claim 5, wherein the laser light emitted from the first laser light source and the laser light emitted from the second laser light source are used. It has a polarization means for polarizing at least one of them in different directions.

  According to the present invention, it is possible to more reliably measure the volume, velocity and position of a droplet simultaneously.

  In order to achieve the above object, according to a tenth aspect of the present invention, in the droplet measuring method, the laser beam from the first laser light source is irradiated to the ejected droplet at a position where the laser beam cross section is irradiated. The light intensity of the laser beam is kept within a predetermined range within a range in which variations in the droplet discharge position in a direction perpendicular to the droplet discharge direction occur, and the laser beam irradiated to the droplet is received. And calculating the volume and velocity of the droplet.

  According to the present invention, since the light intensity of the laser beam falls within a predetermined range within a range in which variations in the droplet discharge position occur in a direction perpendicular to the droplet discharge direction, the droplet generated by the flying curve of the droplet It is possible to accurately measure the volume and velocity of the liquid droplets without being affected by variations in the discharge positions.

  In order to achieve the object, the invention according to claim 11 is the droplet measurement method according to claim 10, wherein the time change of the value of the detection signal generated by receiving the laser beam irradiated to the droplet is detected. A time interval measuring step of measuring and measuring a time interval from when the droplet discharge driving is performed to when a value of the detection signal changes by a predetermined amount, and a correlation between the time interval and the velocity of the droplet And a velocity calculating step for calculating the velocity of the droplet.

  In order to achieve the object, the invention according to claim 12 is the droplet measurement method according to claim 10, wherein the time change of the value of the detection signal generated by receiving the laser beam irradiated to the droplet is detected. A maximum change amount measuring step for measuring and measuring a maximum change amount of the value of the detection signal, and a volume calculation step for calculating the volume of the droplet from the correlation between the maximum change amount and the volume of the droplet. It is characterized by having.

  In order to achieve the above object, according to a thirteenth aspect of the present invention, in the droplet measuring apparatus, a laser beam is provided at a position where the laser beam is emitted from the laser light source to the droplet to be ejected. Optical means for making the light intensity of the laser light non-uniform within a range in which the droplet discharge position varies in a direction perpendicular to the droplet discharge direction with respect to the cross section, and the droplet by the optical means A light receiving means for receiving the laser beam irradiated to the light and generating a detection signal; a droplet discharge position changing means for changing the relative position of the light receiving means and the droplet; and the droplet discharge position change. And a droplet position calculating means for calculating the position of the droplet from a plurality of the detection signals generated at the relative position of the droplet. .

  According to the present invention, it is possible to accurately calculate the position of a droplet from a plurality of detection signals.

  In order to achieve the above object, according to a fourteenth aspect of the present invention, there is provided the droplet measuring apparatus according to the thirteenth aspect, wherein the droplet position calculating means is a relationship between the coordinate value of the relative position and the coordinate value of the detection signal. The position of the droplet is calculated by using an interpolation function in which a coefficient is obtained from the coordinate values of the plurality of detection signals by a least square method.

  According to the present invention, the measurement time of the position of the droplet can be shortened.

  In order to achieve the above object, according to a fifteenth aspect of the present invention, in the liquid droplet measuring apparatus according to the fourteenth aspect, the liquid droplet position calculating means is a quadratic as the interpolation function according to the coordinate values of the plurality of detection signals. One of a function and a cubic function is selected.

  According to the present invention, it is possible to improve the measurement accuracy of the position of a droplet.

  In order to achieve the above object, according to a sixteenth aspect of the present invention, in the droplet measuring device according to the fifteenth aspect, the coordinate values of the plurality of detection signals are set to IS1, IS2, IS3 in descending order of absolute values, When the coordinate values of the relative positions when the coordinate values IS1, IS2, IS3 of the detection signals are detected are XS1, XS2, XS3, the droplet position calculation means is {(IS1-IS2) / When the relational expression | XS1-XS2 |> (IS2-IS3) / | XS2-XS3 |} is satisfied, a cubic function is selected as the interpolation function, and {(IS1-IS2) / | XS1-XS2 | ≦ ( When a relational expression of (IS2-IS3) / | XS2-XS3 |} is satisfied, a quadratic function is selected as the interpolation function.

  According to the present invention, the measurement accuracy of the position of the droplet can be more reliably increased.

  In order to achieve the object, the invention according to claim 17 is the droplet measuring apparatus according to claim 16, wherein the droplet position calculating means is {(IS1-IS2) / | XS1-XS2 | ≦ (IS2-IS3 ) / | XS2-XS3 |} and a quadratic function is selected as the interpolation function, and when there are five coordinate values of the plurality of detection signals, The coefficient of the interpolation function is obtained by the least square method from the top four coordinate values having the largest absolute value among the coordinate values.

  According to the present invention, the measurement accuracy of the position of the droplet can be more reliably increased.

  In order to achieve the above object, according to an eighteenth aspect of the present invention, in the droplet measurement method, the droplet of the laser beam is cross-sectioned at a position where the laser beam from the laser light source is irradiated to the droplet to be ejected. A light receiving means for making the light intensity of the laser light non-uniform within a range in which variations in the ejection position of the droplet in a direction perpendicular to the ejection direction occur, and receiving the laser light irradiated on the droplet; and the liquid The relative position of the droplet is changed, and the position of the droplet is calculated from a plurality of detection signals generated by the light receiving means.

  In order to achieve the above object, according to a nineteenth aspect of the present invention, there is provided a droplet measuring apparatus, comprising: a detection unit that detects a discharged droplet and generates a detection signal; and a relative relationship between the detection unit and the droplet. A droplet discharge position changing means for changing the position; a plurality of detection signals generated at a relative position of the droplet and the detection means changed by the droplet discharge position changing means; And a droplet position calculating means for calculating the position.

  According to the present invention, it is possible to accurately calculate the position of a droplet from a plurality of detection signals.

  In order to achieve the above object, according to a twentieth aspect of the present invention, in the droplet measuring device according to the nineteenth aspect, the droplet position calculating means is a relationship between the coordinate value of the relative position and the coordinate value of the detection signal. The position of the droplet is calculated by using an interpolation function in which a coefficient is obtained from the coordinate values of the plurality of detection signals by a least square method.

  According to the present invention, the measurement time of the position of the droplet can be shortened.

  In order to achieve the above object, according to a twenty-first aspect of the present invention, in the droplet measuring device according to the twenty-second aspect, the droplet position calculating means is a quadratic function as the interpolation function according to a plurality of detection signal values. And calculating by selecting one of the cubic function and the cubic function.

  According to the present invention, it is possible to improve the measurement accuracy of the position of a droplet.

  In order to achieve the above object, according to a twenty-second aspect of the invention, in the droplet measuring device according to the twenty-first aspect, the coordinate values of the plurality of detection signals are set to IS1, IS2, IS3 in descending order of absolute values, When the coordinate values of the relative positions when the coordinate values IS1, IS2, IS3 of the detection signals are detected are XS1, XS2, XS3, the droplet position calculation means is {(IS1-IS2) / When the relational expression | XS1-XS2 |> (IS2-IS3) / | XS2-XS3 |} is satisfied, a cubic number is selected as the interpolation function, and {(IS1-IS2) / | XS1-XS2 | ≦ When the relational expression of (IS2-IS3) / | XS2-XS3 |} is satisfied, a quadratic number is selected as the interpolation function.

  According to the present invention, the measurement accuracy of the position of the droplet can be more reliably increased.

  In order to achieve the above object, according to a twenty-third aspect of the present invention, in the droplet measuring device according to the twenty-second aspect, the droplet position calculating means is {(IS1-IS2) / | XS1-XS2 | ≦ (IS2-IS3 ) / | XS2-XS3 |} and a quadratic function is selected as the interpolation function, and when there are five coordinate values of the plurality of detection signals, The coefficient of the interpolation function is obtained by the least square method from the top four coordinate values having the largest absolute value among the coordinate values.

  According to the present invention, the measurement accuracy of the position of the droplet can be more reliably increased.

  In order to achieve the above object, according to a twenty-fourth aspect of the present invention, in the droplet measuring method, the relative position between the detecting means for detecting the discharged droplet and the position of the droplet is changed, and the detecting means The droplet position is calculated from a plurality of generated detection signals.

  According to the present invention, the volume, velocity, and position of a droplet can be accurately measured by adjusting the light intensity distribution of the beam cross section of the laser light and irradiating the droplet.

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

[Description of Droplet Measurement Device]
<Example 1>
FIG. 1 is a configuration diagram of a droplet measuring apparatus 1 according to a first embodiment, where (a) is a front view and (b) is a bottom view. As shown in FIG. 1, the droplet measuring apparatus 1 of the present invention includes a laser light source 10 (first laser light source), first optical means, first light receiving means, droplet characteristic calculating means 22 and the like.

  The laser light source 10 may be a solid-state laser light source, a liquid laser light source, a gas (gas) laser light source, or the like in addition to a semiconductor laser light source (LD light source). In this embodiment, a semiconductor laser light source (LD light source) is used. This is because the apparatus configuration can be reduced and the cost can be reduced.

  The laser light source 10 is arranged so that the horizontal direction to the joint surface coincides with the droplet discharge direction (Z-axis direction) shown in FIG. As a result, the spread angle of the laser light is reduced in the droplet discharge direction (Z-axis direction), and a Gaussian beam without vignetting can be obtained.

  On the other hand, in the direction perpendicular to the droplet ejection direction (X-axis direction) shown in FIG. 1B, the spread angle of the laser beam becomes large, and side lobes due to vignetting occur. However, in the measurement of the volume, velocity, and position of the droplet in this embodiment, there is no problem because the portion where the side lobe is generated in the beam cross section of the laser light is not used. Therefore, the volume, velocity, and position of the droplet can be accurately measured without being affected by the side lobe.

  The first optical means is configured in the order of the collimator lens 12, the cylindrical lens 14 and the spherical lens 16 from the laser light source 10 side. A photodiode 20 is configured as the first light receiving means. In FIG. 1, the slit 18 (light limiting means) is provided between the first optical means and the first light receiving means, but a specification in which the slit 18 is not provided is also conceivable.

  In the plane shown in FIG. 1 (a), the cylindrical lens 14 has its planar side surface 14a directed toward the liquid droplet ejection position, while the curved side surface 14b is directed toward the laser light source 10, and the bus line is illustrated. It is arranged so as to be perpendicular to the paper surface. The cylindrical lens 14 is arranged so that the laser light incident from the laser light source 10 via the collimator lens 12 is condensed and irradiated at a position where the droplet is discharged.

  In the plane shown in FIG. 1A, the spherical lens 16 focuses the laser light beam 15 that has passed through the position where the droplet is irradiated onto the slit 18 to form an image of the droplet. Is arranged.

  On the other hand, in the plane shown in FIG. 1B, the generatrix of the cylindrical lens 14 is parallel to the drawing sheet, and the refractive power of the cylindrical lens 14 is 0 in the plane shown in FIG. Therefore, in the plane shown in FIG. 1B, the laser light incident from the laser light source 10 via the collimator lens 12 travels as it is spread from the collimator lens 12 after exiting the cylindrical lens 14.

  The droplet characteristic calculation means 22 is a means capable of calculating the volume, velocity and position of the droplet based on the output signal (detection signal) of the photodiode 20 generated by receiving the laser beam. .

  Further, FIG. 1 shows a state in which droplets are discharged from the print head 160 between the cylindrical lens 14 and the spherical lens 16. The print head 160 is assumed to be mounted on an image forming apparatus such as an ink jet printer. In this case, it is conceivable that the droplet measuring apparatus 1 is installed in a unit portion (a print head unit 150 described later) of the print head 160 of the image forming apparatus. In addition, the droplet measuring device 1 may be a component device of the image forming system as a separate device from the image forming device. In FIG. 1B, droplets are ejected from the nozzles of the print head 160 to the front side of the drawing sheet in a direction perpendicular to the drawing sheet.

  The droplet measuring apparatus 1 configured as described above operates as follows. Laser light emitted from the laser light source 10 enters the cylindrical lens 14 via the collimator lens 12. At this time, the cylindrical lens 14 has a curvature in a discharge direction (Z-axis direction) of a droplet discharged from the print head 160, but has a curvature in a direction perpendicular to the discharge direction of the droplet (X-axis direction). It has characteristics that it does not have.

  Then, the laser light after entering the cylindrical lens 14 is condensed in the ejection direction (Z-axis direction) of the droplet having the curvature. By adjusting the curvature of the cylindrical lens 14, the distance between the cylindrical lens 14 and the print head 160, etc., as shown in FIG. 1A, the condensed laser light is converted into droplets discharged from the print head 160. Irradiate.

  The laser light applied to the droplet is condensed by the spherical lens 16 so as to form an image of the droplet at the position of the slit 18. Then, after being condensed, the light is received by the photodiode 20.

  The received photodiode 20 supplies an output signal to the droplet characteristic calculation means 22. The droplet characteristic calculation means 22 calculates the volume and velocity of the droplet based on the output signal.

  Here, a method for calculating the volume and velocity of the droplet in the droplet characteristic calculating means 22 will be described. Now, when one droplet is discharged and the droplet is irradiated with laser light, the output from the photodiode 20 shows the time change of the value of the output voltage (detection signal) generated by receiving the laser light. FIG. 2A shows the voltage waveform, and FIG. 2B shows the driving waveform for discharging the droplets in the print head 160.

  In the calculation of the droplet velocity, first, as shown in FIG. 2, the drive portion of the drive waveform of the droplet discharge (when the droplet discharge drive is performed) and the drop portion of the output voltage waveform in the photodiode 20 ( A time interval ΔTv from when the output voltage value changes by a predetermined amount is measured. In FIG. 13, the threshold level is the output voltage value when the drop amount is 50%, and the time interval ΔTv when the output voltage value is 50% of the drop amount is measured. Next, the droplet velocity V is determined from the measured time interval ΔTv based on a lookup table and a correction formula showing the correlation between the time interval ΔTv and the droplet velocity V created in advance.

  The relationship between the time interval ΔTv and the droplet velocity V can be obtained as follows. First, droplets are continuously ejected from one nozzle, and the time interval ΔTv at the position where the laser beam is moved from the reference position in the droplet velocity measurement to the droplet ejection direction (Z-axis direction) is set. taking measurement. Here, the amount ΔZv of moving the laser beam can be obtained by measurement with a feed amount of a precision stage on which the laser light source is mounted, a laser displacement meter, or the like. Then, the velocity V of the droplet is calculated from the relationship between the amount ΔZv of moving the laser beam and the time interval ΔTv (FIG. 3A) using a least square method or the like. Thereafter, by calculating the droplet velocity V while changing the time interval ΔTv, the relationship between the time interval ΔTv and the droplet velocity V (FIG. 3B) is obtained.

  Next, in the calculation of the volume of the droplet, first, as shown in FIG. 2, the maximum drop amount Ip (maximum change amount of the output voltage value) of the output voltage waveform in the photodiode 20 is measured. Next, based on a lookup table and a correction formula showing the correlation between the maximum drop amount Ip of the output voltage waveform and the volume Vol of the droplet created in advance, the maximum drop amount Ip of the measured output voltage waveform is calculated from the measured drop amount Ip. Determine the volume Vol.

  The relationship between the maximum drop amount Ip of the output voltage waveform and the volume Vol of the droplet can be obtained as follows. First, a non-volatile ink is used to discharge a large amount of droplets, for example, about 106 droplets, and the mass of the droplet reservoir is measured. The mass can be measured not only by directly measuring the mass of the droplet reservoir, but also from the amount of ink reduced in the ink tank for supply to the head for ejecting droplets. Further, the average value of the maximum drop amount Ip of the output voltage waveform for each droplet when discharging a large amount of droplets is measured. After that, by measuring the average value of the maximum drop amount Ip while changing the droplet discharge amount, the relationship between the maximum drop amount Ip of the output voltage waveform and the droplet volume Vol is obtained.

  Here, FIG. 4 shows the light intensity distribution of the beam cross section at the position where the laser beam condensed to irradiate the droplet is irradiated to the droplet. As shown in FIG. 4A, due to the action of the cylindrical lens 14, the laser beam cross section is perpendicular to the droplet discharge direction with respect to the beam width in the droplet discharge direction (Z-axis direction) ( It is formed so that the beam width in the (X-axis direction) is increased, and the droplet discharge direction (Z-axis direction) is narrower than the direction (X-axis direction) in which the light intensity distribution is perpendicular to the droplet discharge direction (X-axis direction). Is formed. If this is shown in the graph as the light intensity in the direction perpendicular to the droplet discharge direction (X-axis direction), it is shown in FIG. As shown in FIG. 4B, the amount of change in the light intensity with respect to the change in the position in the X-axis direction is very small due to the action of the cylindrical lens 14 in the range of the beam width X1 in the X-axis direction. For this reason, the value of the light intensity is within a small range within the range of the beam width X1 in the X-axis direction.

  Therefore, as shown in FIG. 4A, a case where the first droplet d1 and the second droplet d2 are ejected at different ejection timings will be described. It is assumed that the first droplet d1 and the second droplet d2 have the same volume and the same velocity. The first droplet d1 is ejected at an ideal ejection position in the direction perpendicular to the droplet ejection direction (X-axis direction), and the second droplet d2 is ejected from the first droplet d1. Suppose that the ink is discharged at a position that is outside the distance δ. It is assumed that the second droplet d2 is ejected in a state in which the flying bend is generated due to, for example, dirt on the nozzle portion of the print head 160 or the like.

  At this time, the time axes of the voltage values of the output signal in the photodiode 20 when the first droplet d1 is ejected and when the second droplet d2 is ejected are aligned with each other. This is shown in FIG. 5 (a). FIG. 5B shows droplet ejection driving waveforms in the print head 160 when the first droplet d1 is ejected and when the second droplet d2 is ejected.

  As shown in FIG. 5A, when the first droplet d1 is ejected and when the second droplet d2 is ejected, the amount of output voltage waveform drop in the photodiode 20 is substantially equal, and The temporal timing of the drop in the output voltage waveform is almost the same. This means that even when droplets with the same volume and the same velocity are ejected at a position that is out of the distance δ, the volume and velocity can be accurately measured regardless of the variation in the ejection position. ing.

  The reason why the volume and speed can be accurately measured regardless of the variation in the ejection position as described above is as follows. As shown in FIG. 4A, in the droplet measuring apparatus 1 according to the present embodiment, the light intensity distribution in the beam cross section of the laser light irradiated on the droplet is expressed by the droplet lens discharge direction by the action of the cylindrical lens 14. It is narrowed in the (Z-axis direction). As a result, the light intensity of the laser light at the discharge position of the first droplet d1 in the direction perpendicular to the discharge direction of the droplet (X-axis direction) and the discharge position of the second droplet d2 in which the flight curve has occurred. This is because it falls within a predetermined range that does not affect the measurement of the volume and velocity of the droplet.

  As described above, in the direction perpendicular to the droplet ejection direction (X-axis direction), the light intensity of the laser beam is in the range of the volume and velocity of the droplet within the region where the variation in the droplet ejection position due to the flight curve occurs. By falling within a predetermined range that does not affect the measurement, the volume and velocity of the droplet can be accurately measured even when the flying curve of the droplet occurs.

  Here, when the light intensity of the laser beam falls within a predetermined range, a desirable range as the predetermined range enables measurement of 1% unit of the ideal volume with respect to the volume of the droplet, and 1 for the speed of the droplet. It is a range that allows measurement in% units. The ideal volume of the droplet is a volume having a diameter of φ10 μm to φ30 μm and a droplet amount of 0.5 pl to 15 pl.

  Here, specific conditions for enabling measurement of the droplet volume in units of 1% of the ideal volume are considered. Therefore, the applicant conducted verification by simulation by the following method.

  FIG. 6 shows a Gaussian beam profile (Gaussian beam light amount distribution) used in the simulation. FIG. 6A shows a state where the Gaussian beam is not kicked by a droplet, and FIG. 6B shows a state where the Gaussian beam is kicked by a 2 pl droplet. FIG. 6 shows a case where the Gaussian beam width is set to 100 μm in the X-axis direction and 40 μm in the Z-axis direction as an example of the beam width.

  7, the horizontal axis represents the droplet discharge position (μm) in the X-axis direction, the vertical axis represents the integrated light amount (au) obtained by integrating the light amount in the light amount distribution, and the Gaussian beam profile shown in FIG. The simulation results used are shown. In FIG. 7, as an example of the simulation result, the results regarding the volume of two types of droplets are shown with the droplet amount being 2 pl and 2.5 pl. At this time, in FIG. 7, when the variation in the discharge position of the droplet in the X axis direction in the volume of 2 pl is 20 μm (when the discharge position of the droplet in the X axis direction is compared between 0 μm and −20 μm), the light amount difference is δL. The light amount difference due to the variation in the volume of the droplets (volume of two types of droplets) is expressed as δV.

  8 to 11, the horizontal axis indicates the beam width (μm) in the X-axis direction, and the vertical axis indicates the light amount difference (%), giving various variations in the droplet volume and droplet discharge position. The results of the above simulation are shown. 8 to 11, assuming that the droplet volume for realizing the ideal droplet volume serving as a reference is 20 pl and 2 pl, respectively, it is assumed that the variation in the volume of the droplet has occurred. The results are shown in Fig. 5 where ± 1% and ± 2% of the ideal droplet volume. For example, when considering a high-quality inkjet printer, it is required that the variation in the volume of droplets is 1% or less of the ideal volume. Therefore, as a verification condition, the variation in droplet volume was set to ± 1% and ± 2% with respect to the ideal droplet volume.

  At the same time, FIGS. 8 to 11 show the results when the droplet ejection positions are shifted by 20 μm and 30 μm from the ideal droplet ejection position as a reference. For example, when considering an ink jet printer of 600 pdi or 1200 pdi, generally, as a characteristic of a print head, a variation in ejection position due to a flying curve is required to be 20 μm or less. Therefore, as a verification condition, the variation of the droplet discharge position was set to a position shifted by 20 μm and 30 μm from the ideal discharge position.

  8 and 10 show the results when the beam width in the Z-axis direction is 40 μm, and FIGS. 9 and 11 show the results when the beam width in the Z-axis direction is 60 μm.

  8 and 9, when the beam width in the X-axis direction is 1000 μm, the light amount difference when the droplet volume variation is ± 1% and the light amount difference when the droplet discharge position variation is 30 μm. It is almost equal. When the beam width in the X-axis direction is 1000 μm or less, the light amount difference when the variation in the droplet ejection position is 30 μm is larger than the light amount difference when the variation in droplet volume is ± 1%. .

  Therefore, when the beam width in the X-axis direction is 1000 μm or less, when the variation in the droplet ejection position is 30 μm, even if the variation in droplet volume is ± 1%, it is expressed as a light amount difference. In other words, the variation in droplet volume cannot be measured.

  Therefore, when the beam width in the X-axis direction is 1000 μm or less, the variation in the volume of the droplet cannot be measured due to the difference in the light amount due to the influence of the variation in the ejection position of the droplet, and the volume of the droplet may not be measured accurately. I can say that.

  Similarly, in FIGS. 10 and 11, when the beam width in the X-axis direction is 600 μm or less, the variation in droplet volume cannot be measured due to the difference in the light amount due to the variation in the droplet ejection position, and the volume of the droplet is not measured. It can be said that there are cases where accurate measurement is not possible.

  As shown in FIGS. 8 to 11, the beam width in the X-axis direction is 1000 μm or less when the droplet amount is 20 pl, the beam width in the Z-axis direction is 40 μm or 60 μm, and the droplet amount is less than 1000 μm. Is 2 pl, the beam width in the X-axis direction is 600 μm or less, and it can be seen that the light amount difference due to the variation in the droplet ejection position (30 μm) is larger than the light amount difference due to the variation in the droplet volume (± 1%). .

  Therefore, in order to make the light amount difference due to variation in the droplet ejection position (30 μm) smaller than the light amount difference due to variation in the volume of the droplet (± 1%), even when the beam width in the Z-axis direction is 40 μm, it is 60 μm. Sometimes, the beam width in the X-axis direction is required to be 1000 μm or more when the droplet amount is 20 pl, and the beam width in the X-axis direction is required to be 600 μm or more when the droplet amount is 2 pl.

  Here, in order to accurately measure the volume of the droplet without being affected by the variation in the droplet ejection position, the difference in the amount of light due to the variation in the droplet ejection position It is desirable to make it a small value that is 10% or less. Therefore, in order to realize this, it can be understood from FIGS.

  Based on the above simulation results, the light of the laser beam in the direction perpendicular to the droplet ejection direction (X-axis direction) in order to accurately measure the volume of the droplet regardless of variations in the droplet ejection position due to flying bends. In order to keep the intensity distribution within a predetermined range, a desirable range as the predetermined range is a range in which the light amount difference due to variations in droplet ejection positions is 10% or less due to variations in droplet volume. . As a condition for realizing this range, the beam width in the X-axis direction is preferably 2000 μm or more. The beam width in the Z-axis direction is desirably 30 μm to 100 μm.

  FIG. 12 is a diagram showing the slit 18. By providing the slit 18 between the spherical lens 16 and the photodiode 20, an image of the droplet d is formed on the slit 18 by the spherical lens 16 while limiting the laser light incident on the photodiode 20. By doing so, the difference (extinction ratio) of received light intensity in the photodiode 20 when the image of the droplet d is formed and when it is not formed is increased, and the volume of the droplet d and Speed can be measured with high accuracy. If the slit 18 is not provided in the droplet measuring device 1, the spherical lens 16 forms an image of the droplet d on the light receiving surface of the photodiode 20.

Further, since the laser light from the laser light source 10 is complementary to the color of the droplet to be measured, the laser light irradiated to the droplet can be reflected or absorbed, and the volume and velocity of the droplet can be accurately set. Can be measured. The relationship between the laser light and the complementary color of the droplet is shown in FIG.

<Example 2>
A droplet measuring device 2 as shown in FIG. 14 is also conceivable. In the droplet measuring apparatus 2 according to the second embodiment, the optical unit includes the collimator lens 12, the cylindrical lens 24, the cylindrical lens 26, and the spherical lens 16 in this order from the laser light source 10 side.

  In the plane shown in FIG. 14A, the generatrix of the cylindrical lens (24, 26) is parallel to the drawing sheet, and the refractive power of the cylindrical lens (24, 26) is zero. Therefore, in the plane shown in FIG. 14A, the laser light incident from the laser light source 10 via the collimator lens 12 spreads when it exits from the collimator lens 12 after exiting from the cylindrical lenses (24, 26). Continue on.

  On the other hand, in the plane shown in FIG. 14B, the cylindrical lens 24 has its planar side surface 24a facing the laser light source 10 side, while its curved side surface 24b faces the cylindrical lens 26 side. It is arranged so as to be perpendicular to the paper surface. The cylindrical lens 24 is disposed so as to condense the laser light incident from the laser light source 10 via the collimator lens 12 with the cylindrical lens 26.

  In addition, in the plane shown in FIG. 14B, the cylindrical lens 26 has its planar side surface 26a directed toward the droplet ejection position, while the curved side surface 26b is directed toward the cylindrical lens 24, and the generatrix is They are arranged so as to be perpendicular to the drawing sheet. The cylindrical lens 26 enters the laser beam once condensed and spread again by the cylindrical lens 24 on the planar side surface 26a and exits from the curved side surface 26b.

  The curvature radius of the cylindrical lens 26 is larger than that of the cylindrical lens 24. As a result, as shown in FIG. 14B, the laser light after exiting the cylindrical lens 26 greatly spreads in the direction perpendicular to the droplet discharge direction (X-axis direction).

  Other configurations are the same as those of the droplet measuring apparatus 1 of the first embodiment.

  The droplet measuring device 2 configured as described above operates as follows. Laser light emitted from the laser light source 10 enters the cylindrical lens 24 via the collimator lens 12. At this time, the cylindrical lens 24 has a curvature in the direction (X-axis direction) perpendicular to the discharge direction of the droplets discharged from the print head 160, but has a curvature in the discharge direction (Z-axis direction) of the droplets. It has characteristics that it does not have.

  Then, the laser light after entering the cylindrical lens 24 is once condensed in a direction (X-axis direction) perpendicular to the discharge direction of the droplet having the curvature.

  Once condensed, the laser light spreads again and enters the cylindrical lens 26. At this time, the cylindrical lens 26 has a curvature in a direction (X-axis direction) perpendicular to the discharge direction of the droplets discharged from the print head 160, but has a curvature in the discharge direction (Z-axis direction) of the droplets. It has characteristics that it does not have. For this reason, the laser light after exiting the cylindrical lens 26 spreads greatly in the direction perpendicular to the droplet discharge direction (X-axis direction) and proceeds with the spread, and is irradiated to the droplets discharged from the print head 160. The

  The laser light applied to the droplet is condensed by the spherical lens 16 so as to form an image of the droplet at the position of the slit 18. Then, after being condensed, the light is received by the photodiode 20.

  The received photodiode 20 supplies an output signal to the droplet characteristic calculation means 22. The droplet characteristic calculation means 22 calculates the volume and velocity of the droplet based on the output signal.

  Also with the droplet measuring apparatus 2 of Example 2 as described above, as shown in FIG. 4A, the light intensity distribution is a direction perpendicular to the droplet ejection direction by the action of the cylindrical lenses (24, 26). The droplet discharge direction (Z-axis direction) is narrower than (X-axis direction).

  Therefore, in the direction perpendicular to the droplet discharge direction (X-axis direction), the light intensity of the laser beam affects the measurement of the volume and velocity of the droplet in a region where the droplet discharge position varies due to flying bends. The volume and velocity of the droplet can be accurately measured even when a flying bend occurs.

  Further, the effect of the slit 18 and the effect of setting the wavelength to have the complementary color of the droplet for measuring the laser beam from the laser light source 10 are the same as those of the droplet measuring apparatus 1 of the first embodiment.

<Example 3>
A droplet measuring device 3 as shown in FIG. 15 is also conceivable. In the droplet measuring device 3 of the third embodiment, the optical means is configured in the order of the collimator lens 12, the diffusion plate 28, the spherical lens 32, the spherical lens 34, the spherical lens 38, and the spherical lens 16 from the laser light source 10 side.

  Thus, the spherical lens 32 and the spherical lens 34 are arranged between the diffusion plate 28 and the droplet discharge path, and the spherical lens 32 and the droplet, and the diffusion plate 28 and the spherical lens 34 are optically conjugate with each other. Arrange so that

  The diffusion plate 28 diffuses laser light only in the direction perpendicular to the droplet discharge direction (X-axis direction), so that the laser light is not diffused in the droplet discharge direction (Z-axis direction) and Gaussian. While it becomes a beam, a portion having a uniform light intensity can be formed in a direction (X-axis direction) perpendicular to the droplet discharge direction. The diffusion plate 28 may have a characteristic of diffusing laser light not only in the direction (X-axis direction) perpendicular to the droplet discharge direction but also in the droplet discharge direction (Z-axis direction).

  Other configurations are the same as those of the droplet measuring apparatus 1 of the first embodiment.

  The droplet measuring device 3 configured as described above operates as follows. Laser light emitted from the laser light source 10 enters the diffusion plate 28 via the collimator lens 12. Then, the laser light after entering the diffusion plate 28 is diffused. At this time, as described above, the diffusion plate 28 diffuses the laser light only in the direction perpendicular to the droplet discharge direction (X-axis direction), so that the laser is emitted in the droplet discharge direction (Z-axis direction). While the light is not diffused and becomes a Gaussian beam, a portion having a uniform light intensity can be formed in the direction perpendicular to the droplet ejection direction (X-axis direction).

  The diffused laser light is collected in the droplet discharge direction (Z-axis direction) and the direction perpendicular to the droplet discharge direction (X-axis direction) by the spherical lens 38 via the spherical lens 32 and the spherical lens 34. After being illuminated, the liquid droplets ejected from the print head 160 are irradiated.

  The laser light applied to the droplet is condensed by the spherical lens 16 so as to form an image of the droplet at the position of the slit 18. Then, after being condensed, the light is received by the photodiode 20.

  The received photodiode 20 supplies an output signal to the droplet characteristic calculation means 22. The droplet characteristic calculation means 22 calculates the volume and velocity of the droplet based on the output signal.

  According to the droplet measuring apparatus 3 of Example 3 as described above, the light intensity distribution of the laser light when irradiating the droplet is liquid by the action of the diffusion plate 28 as shown in FIG. The strength is almost uniform in the direction perpendicular to the droplet ejection direction (X-axis direction). When the light intensity in the direction perpendicular to the droplet discharge direction (X-axis direction) is shown in a graph, the light intensity in the droplet discharge direction (Z-axis direction) is shown in FIG. As shown in FIG. 16 (c).

  Therefore, in the direction perpendicular to the droplet discharge direction (X-axis direction), the light intensity distribution of the laser light has a substantially uniform intensity in a region where variations in the droplet discharge position due to flight bending occur. By doing so, the volume and velocity of the droplet can be accurately measured even when a flying curve occurs.

  Further, the effect of the slit 18 and the effect of setting the wavelength to have the complementary color of the droplet for measuring the laser beam from the laser light source 10 are the same as those of the droplet measuring apparatus 1 of the first embodiment.

<Example 4>
A droplet measuring device 4 as shown in FIG. 17 is also conceivable. In the droplet measuring device 4 of the fourth embodiment, as shown in FIG. 17A, the optical means is configured in the order of the fly eye lens 40, the fly eye lens 42, the spherical lens 46, and the spherical lens 16 from the laser light source 10 side. Is done.

  As described above, the fly eye lens 40 and the fly eye lens 42 are arranged between the laser light source 10 and the spherical lens 46, and the object points of the laser light source 10 and the fly eye lens 42, the fly eye lens 40 and the spherical lens 46 are determined. They are arranged so as to have an optically conjugate relationship.

  As the fly-eye lenses (40, 42), those having a curvature only in one direction as shown in FIG. 17B are used, and the curvature is given only in the direction perpendicular to the droplet discharge direction (X-axis direction). As a result, the laser beam is not diffused in the droplet discharge direction (Z-axis direction) but becomes a Gaussian beam, while the light intensity is uniform in the direction perpendicular to the droplet discharge direction (X-axis direction). Can be formed. Note that the fly-eye lens (40, 42) has a curvature in both directions as shown in FIG. 17 (c), and not only the direction perpendicular to the droplet discharge direction (X-axis direction), The liquid droplet ejection direction (Z-axis direction) may have a curvature.

  Other configurations are the same as those of the droplet measuring apparatus 1 of the first embodiment.

  The droplet measuring device 4 configured as described above operates as follows. Laser light emitted from the laser light source 10 enters the fly-eye lens (40, 42). Then, the laser light after entering the fly-eye lens (40, 42) is diffused. At this time, as described above, the fly-eye lens (40, 42) diffuses the laser beam only in the direction perpendicular to the droplet ejection direction (X-axis direction), so that the droplet ejection direction (Z-axis) In the direction), the laser beam is not diffused and becomes a Gaussian beam, while a portion having a uniform light intensity can be formed in the direction perpendicular to the droplet discharge direction (X-axis direction).

  The diffused laser light is condensed by the spherical lens 46 in the droplet discharge direction (Z-axis direction) and the direction perpendicular to the droplet discharge direction (X-axis direction), and then discharged from the print head 160. Irradiate the droplet.

The laser light applied to the droplet is condensed by the spherical lens 16 so as to form an image of the droplet at the position of the slit 18. Then, after being condensed, the light is received by the photodiode 20.

  The received photodiode 20 supplies an output signal to the droplet characteristic calculation means 22. The droplet characteristic calculation means 22 calculates the volume and velocity of the droplet based on the output signal.

  According to the droplet measuring device 4 of the fourth embodiment as described above, the light intensity distribution of the laser light when the droplet is irradiated is similar to that of the droplet measuring device 3 of the third embodiment, as shown in FIG. ), The fly-eye lens (40, 42) has a substantially uniform strength in the direction perpendicular to the droplet discharge direction (X-axis direction). When the light intensity in the direction perpendicular to the droplet discharge direction (X-axis direction) is shown in a graph, the light intensity in the droplet discharge direction (Z-axis direction) is shown in FIG. As shown in FIG. 16 (c).

  Therefore, in the direction perpendicular to the droplet discharge direction (X-axis direction), the light intensity distribution of the laser light has a substantially uniform intensity in a region where variations in the droplet discharge position due to flight bending occur. By doing so, the volume and velocity of the droplet can be accurately measured even when a flying curve occurs.

  Further, the effect of the slit 18 and the effect of setting the wavelength to have the complementary color of the droplet for measuring the laser beam from the laser light source 10 are the same as those of the droplet measuring apparatus 1 of the first embodiment.

<Example 5>
A droplet measuring device 5 as shown in FIG. 18 is also conceivable. In the droplet measuring device 5 of the fifth embodiment, the optical means is configured in the order of the collimator lens 52, the spherical lens 48, and the spherical lens 56 from the laser light source 50 side. A photodiode 60 is configured as the light receiving means. In FIG. 18, the slit 58 is provided between the optical means and the light receiving means, but a specification without the slit 58 is also conceivable.

  The laser light source 50, the collimator lens 52, the spherical lens 56, the slit 58, and the photodiode 60 are the same as the laser light source 10, the collimator lens 12, the spherical lens 16, the slit 18, and the photodiode 20 of the droplet measuring device 1 of the first embodiment. It has a simple structure and action.

  Other configurations are the same as those of the droplet measuring apparatus 1 of the first embodiment.

  The droplet measuring device 5 configured as described above operates as follows. Laser light emitted from the laser light source 10 is incident on the spherical lens 48 via the collimator lens 12.

  The laser light after entering the spherical lens 48 is condensed in the droplet discharge direction (Z-axis direction) and in the direction perpendicular to the droplet discharge direction (X-axis direction). By adjusting the curvature of the spherical lens 48, the distance between the spherical lens 48 and the print head 160, and the like, the condensed laser light is irradiated onto the droplets ejected from the print head 160 as shown in FIG.

  The laser light applied to the droplet is condensed by the spherical lens 16 so as to form an image of the droplet at the position of the slit 18. Then, after being condensed, the light is received by the photodiode 20.

  The received photodiode 20 supplies an output signal to the droplet characteristic calculation means 22. The droplet characteristic calculation means 22 calculates the volume and velocity of the droplet based on the output signal.

  According to the droplet measuring apparatus 5 of the fifth embodiment as described above, the light intensity of the laser light irradiated onto the droplet by the spherical lens 48 has a Gaussian beam distribution. Therefore, as shown in FIG. 19, the light of the laser beam is within the region where the droplet is bent in the droplet ejection direction (Z-axis direction) and the direction perpendicular to the droplet ejection direction (X-axis direction). Intensity becomes uneven. When the light intensity in the direction perpendicular to the droplet discharge direction (X-axis direction) and the droplet discharge direction (Z-axis direction) is shown in the graph, it is shown as FIGS. 19B and 19C, respectively. .

  Therefore, as shown in FIG. 19A, the case where the first droplet d1 and the second droplet d2 are ejected at different ejection timings will be described. It is assumed that the first droplet d1 and the second droplet d2 have the same volume and the same velocity. The first droplet d1 is ejected at an ideal ejection position in the direction perpendicular to the droplet ejection direction (X-axis direction), and the second droplet d2 is ejected from the first droplet d1. Suppose that the ink is discharged at a position that is outside the distance δ. It is assumed that the second droplet d2 is ejected in a state in which the flying bend is generated due to, for example, dirt on the nozzle portion of the print head 160 or the like.

  At this time, the time axes of the voltage values of the output signal in the photodiode 20 when the first droplet d1 is ejected and when the second droplet d2 is ejected are aligned with each other. As shown in FIG. 19 (d).

  As shown in FIG. 19 (d), the maximum drop amount of the output voltage waveform in the photodiode 20 is larger when the first droplet d1 is ejected than when the second droplet d2 is ejected. . Further, the timing of the start of the drop of the output voltage waveform is different between when the first droplet d1 is discharged and when the second droplet d2 is discharged, and the second droplet d2 is discharged. The first droplet d1 is ejected faster than the first droplet d1.

  This means that when the droplets having the same volume and the same velocity are ejected to a position that is out of the distance δ, the variation in the ejection position can be measured.

  The reason why the variation in the ejection position can be measured as described above is as follows. As shown in FIG. 19A, in the droplet measuring device 5 in the present embodiment, due to the action of the spherical lens 48, the droplet ejection direction (Z-axis direction) and the direction perpendicular to the droplet ejection direction ( With respect to the X-axis direction), the light intensity of the laser light is made non-uniform. As a result, the light intensity of the laser light at the discharge position of the first droplet d1 in the direction perpendicular to the discharge direction of the droplet (X-axis direction) and the discharge position of the second droplet d2 in which the flight curve has occurred. Because it has changed.

  As described above, the position of the droplet can be accurately measured by making the light intensity of the laser light non-uniform in the direction perpendicular to the droplet discharge direction (X-axis direction).

  Here, a method for calculating the position of the droplet in the droplet characteristic calculating means 22 will be described.

  In calculating the position of the droplet, first, as shown in FIG. 2A, the maximum drop amount Ip of the output voltage waveform in the photodiode 20 is measured. Next, based on a lookup table and a correction formula indicating the relationship between the maximum drop amount Ip of the output voltage waveform and the droplet position Xp prepared in advance, the position of the droplet is determined from the measured maximum drop amount Ip of the output voltage waveform. Xp is obtained.

  The relationship between the maximum drop amount Ip of the output voltage waveform and the droplet position Xp can be obtained as follows. First, droplets are continuously ejected from one nozzle, and the maximum drop in the output voltage waveform when the laser beam is moved from the reference position in the droplet velocity measurement to the position in the nozzle alignment direction (X-axis direction) The quantity Ip is measured. Here, the amount ΔXp by which the laser beam is moved can be obtained by measurement with a feed amount of a precision stage on which the laser light source is mounted or a laser displacement meter. In this manner, as shown in FIG. 20, the relationship between the maximum drop amount Ip of the output voltage waveform and the droplet position Xp is obtained.

<Example 6>
A droplet measuring device 6 as shown in FIG. 21 is also conceivable. In the droplet measuring apparatus 6 of Example 6, as shown in FIG. 21, dichroic is used as specific element transmitting means (62, 64) that transmits only a specific wavelength or polarization plane and reflects other wavelengths or polarization planes. By arranging the mirror and the polarization beam splitter, the configuration of the droplet measuring device 1 of the first embodiment and the configuration of the droplet measuring device 5 of the fifth embodiment are combined on the same plane.

  When a dichroic mirror is used as the specific element transmitting means (62, 64), laser light emitted from the laser light source 10 as the first laser light source and laser light emitted from the laser light source 50 as the second laser light source. The light has different wavelengths. Thereby, for example, as shown in FIG. 21, the dichroic mirror can transmit only the laser light emitted from the laser light source 10 and reflect the laser light emitted from the laser light source 50.

  When a polarization beam splitter is used as the specific element transmitting means (62, 64), the laser light emitted from the laser light source 10 as the first laser light source and the laser light source 50 as the second laser light source are emitted. For example, the polarization planes of the laser beams are different as P-polarized light and S-polarized light, respectively. Thereby, for example, as shown in FIG. 21, the polarization beam splitter can transmit only the laser light emitted from the laser light source 10 and reflect the laser light emitted from the laser light source 50.

  In addition, the laser irradiated from the laser light source 50 which is the 1st droplet characteristic calculation means which calculates the volume and speed | velocity | rate of a droplet with the laser beam irradiated from the laser light source 10 which is a 1st laser light source, and the 2nd laser light source Both the second droplet characteristic calculating means for calculating the position of the droplet by light are provided in the droplet characteristic calculating means 22, but they may be provided as separate droplet characteristic calculating means.

  In addition, the configuration of the droplet measuring device 2 according to the second embodiment, the configuration of the droplet measuring device 5 according to the fifth embodiment, the configuration of the droplet measuring device 3 according to the third embodiment, and the droplet measuring device 5 according to the fifth embodiment. The configuration may be a combination of the configuration of the droplet measuring device 4 of the fourth embodiment and the configuration of the droplet measuring device 5 of the fifth embodiment.

  According to the droplet measuring apparatus 6 of Example 6 as described above, the volume, velocity, and position of the droplet can be measured simultaneously.

  In addition, the laser light emitted from the laser light source 10 and the laser light emitted from the laser light source 50 have different wavelengths, and the configuration of the droplet measuring device 1 of Example 1 and that of Example 5 are set on the same plane. It is good also as a structure which combined the structure of the droplet measuring apparatus 5, and another said combination structure.

<Example 7>
A droplet measuring device 7 as shown in FIG. 22 is also conceivable. In the droplet measuring apparatus 7 of the seventh embodiment, the optical unit is configured in the order of the collimator lens 52, the spherical lens 48, and the spherical lens 56 from the laser light source 50 side. A photodiode 60 is configured as the light receiving means. In FIG. 22, the slit 58 is provided between the optical means and the light receiving means, but a specification in which the slit 58 is not provided is also conceivable.

  The laser light source 50, the collimator lens 52, the spherical lens 56, the slit 58, and the photodiode 60 are the same as the laser light source 10, the collimator lens 12, the spherical lens 16, the slit 18, and the photodiode 20 of the droplet measuring device 1 of the first embodiment. It has a simple structure and action.

  The droplet measuring device 7 according to the seventh embodiment includes a head precise positioning and moving mechanism 70 that positions the print head 160, and a signal sampling unit 72 that is disposed between the photodiode 60 and the droplet characteristic calculating unit 22. Other configurations are the same as those of the droplet measuring apparatus 1 of the first embodiment.

  The print head 160 is moved relative to the optical means and the light receiving means (hereinafter referred to as “optical system” in the seventh embodiment) by the head precise positioning and moving mechanism 70 provided with the actuator, and the position is sequentially changed. Is positioned. Thereby, the relative positions of the nozzles of the print head 160 and the photodiode 60 can be changed. The moving direction is a direction (X-axis direction) substantially perpendicular to the traveling direction of the laser beam shown in FIG. The amount of movement of the print head 160 depends on the accuracy of the ejection direction of the droplets ejected by the nozzles of the print head 160 to be measured, but is moved at regular intervals and at regular intervals. The amount of movement of the print head 160 is not limited to being moved at regular intervals.

  Further, the position of the nozzle to be measured is specified within a certain error range, which is the distance from the head mounting abutment reference when the print head 160 is mounted. Therefore, the approximate passage position of the droplet to be measured indicated by the dotted line in FIG. 22 is also specified from the position of this nozzle. Therefore, for example, it can be specified that the droplet passes through a position of X mm from the abutment reference and a range of ± 50 μm.

  Therefore, in this embodiment, with respect to the nozzle to be measured, a position Xmm−50 μm from the abutment reference is set as a measurement start position, a position Xmm + 50 μm at a predetermined interval is set as a measurement end position, and the print head 160 is moved to precisely position the head. By the mechanism 70, the position is sequentially changed and positioned, and the droplet is detected by the optical system at each positioning point.

  Here, the intensity distribution of the laser beam condensed by the spherical lens 48 which is the first condenser lens is a Gaussian distribution as shown in FIGS. 19B and 19C.

  The droplets ejected from the print head 160 are ejected to the condensing position of the spherical lens 48 in the Y-axis direction, and the print head 160 and the optical system are relatively positioned at a position where they pass through the laser beam. Then, as shown in FIG. 19A, since a part of the laser beam is shielded, the amount of light detected by the photodiode 60 is determined when the droplet passes through the laser beam as shown in FIG. Detected as low light intensity.

  That is, when the droplets are ejected by changing the relative positions of the print head 160 and the optical system, the ejection positions of the ejected droplets and the concentration of the laser light are collected as droplets d1 and d2 in FIG. Since the light position changes, as described above, the intensity distribution of the laser light is a Gaussian distribution as shown in FIGS. 19B and 19C, so that the droplet has passed through the laser light. The amount of light detected by the photodiode 60 varies depending on the position. Therefore, as shown in FIG. 19D, the waveform of the voltage change according to the position where the droplet has passed with respect to the laser beam from the signal sampling means 72 that samples the electric signal proportional to the light amount detected by the photodiode 60. Is obtained.

  In this embodiment, the temperature of the entire measuring apparatus and the laser light source 50 are controlled by temperature control means (not shown) to maintain a substantially constant temperature. Therefore, the light quantity distribution of the laser beam shown in FIG. The light quantity is kept constant by a light quantity feedback means (not shown) so that the light quantity is also constant.

  Further, as described above, the print head 160 is positioned by the head precision positioning movement mechanism 70, and in this embodiment, the position of the print head 160 can be specified with a resolution of 50 nm.

  Therefore, first, the print head 160 and the print head 160 are arranged so that the apex portion of the Gaussian distribution shown in FIGS. 19B and 19C comes to the design (ideal) passage position of the droplets ejected from the nozzle to be measured. Adjust the relative position of the optical system. Then, as described above, the print head 160 and the optical system are changed in relative position, and the liquid droplets ejected from the nozzle to be measured shield the laser beam and reduce the light amount most. And measure the relative position of the optical system. Then, from the relative position of the measured print head 160 and the optical system, the actual flight position from the positioning reference of the print head 160 can be obtained for the liquid droplets ejected from the nozzle to be measured.

  For example, in the case shown in FIG. 19D, since the droplet d1 passes through the position where the laser beam has the largest amount of light, the relative relationship between the head 160 and the optical system when the droplet d1 is ejected. Based on the specific position, the position from the positioning reference of the print head 160 can be obtained for the actual flight position of the droplet ejected from the nozzle to be measured.

  Then, the actual flying position from the determined positioning reference of the print head 160 and the flying position from the designed (ideal) positioning reference of the print head 160 are compared to determine the variation in the flying position of the droplets. I can do it.

  As described above, the actual flying position from the positioning reference of the print head 160 is obtained for the droplets of each nozzle, and each flying position is compared with the design value (ideal value), whereby the droplet flying position for each nozzle. Can be obtained.

  However, in order to determine the positional relationship between the print head 160 and the optical system that reduces the amount of light most when a droplet ejected from a specific nozzle blocks the laser light, the positions of the print head 160 and the optical system are changed finely. This is inefficient because it requires many measurements. In this embodiment, the discharge position variation is measured at a position 0.7 mm from the nozzle surface of the print head 160, and the position variation error of the print head 160 at this position is σ = 0.7 μm. Therefore, in order to detect this error, it is necessary to obtain the positional relationship between the print head 160 and the optical system, which reduces the light amount most, by repeating the above measurement at an interval smaller than this, in fact, at an interval of 0.1 μm.

  In other words, if the position of a droplet that appears to be within a range of ± 50 μm from the design position is measured at intervals of 0.1 μm, a maximum of 1001 measurements are required.

  Ink jet heads in recent years tend to increase the number of nozzles, but the same applies to the print head 160 of the present application. The print head 160 incorporated in the apparatus has about 35,000 nozzles per color, and 140000 for four colors. There are nozzles. Therefore, if one nozzle is measured for one device, more than 140 million measurements are required. The number of times of measurement can be reduced to a certain extent by narrowing the measurement range on the assumption that the error of each nozzle is small, but this is not a fundamental solution.

  In this embodiment, the positional relationship between the print head 160 and the optical system at the time of the above measurement is set to be much larger than the above-described 0.1 μm interval necessary for obtaining the error. As an example, at an interval of 2 μm or 5 μm. By moving at equal intervals and measuring the light amount decrease when the droplet shields the laser beam at a small number of measurement positions, the measured value is measured by a droplet processing unit 22 shown in FIG. Processing is performed to determine the position at which droplets decrease the light amount most, that is, the position at which the droplet passes through the optical axis with the largest amount of laser light, for each droplet discharged from each nozzle. Based on the positional relationship between the print head 160 and the optical system at this time, the flying positions of the droplets ejected from each nozzle are obtained.

  Therefore, a data processing method for obtaining the position when the droplet passes through the optical axis with the largest amount of laser light from the measured value will be described below.

  FIG. 23 is a diagram illustrating a result of measuring a light amount reduction amount when a droplet ejected from a measurement target nozzle shields laser light. FIG. 23 (a) shows the result when the print head 160 is measured while being moved at intervals of 5 μm, and FIG. 23 (b) is the result when the print head 160 is measured while being moved at intervals of 2 μm.

  In FIG. 23, the horizontal axis indicates the relative position between the print head 160 and the optical system, and the distance from the positioning reference position of the print head 160 is expressed in μm as a coordinate value. The vertical axis indicates the voltage value (unit: V) from the result of sampling the output of the light amount decrease detected by the photodiode 60 by the signal sampling means 72 as the measurement value. In FIG. 23, the measurement values at each measurement point are shown as triangles or rhombus plots. Of these, the measurement values to be calculated in the data processing method described later are shown as triangle plots. In addition, the triangle plots are respectively given symbols S1 to S5. In addition, the symbol of S1-S5 is attached | subjected in order with the big absolute value of the measured value.

  In FIG. 23 (a), the light quantity is the largest at the measurement point with S1 (hereinafter expressed as measurement point S1. The measurement points with S2, S3, S4, and S5 are also expressed in the same manner). It shows that the amount of decrease is large, and then the amount of light amount decrease is large at the measurement point S2. That is, S1, S2, S3, S4, and S5 are given in order of decreasing light amount.

  Therefore, between the measurement point S1 and the measurement point S2, the position where the light amount decrease amount is the largest, that is, the position where the droplet passes through the optical axis with the largest amount of laser light (circular plot is attached in the figure). Position). In FIG. 23A, the measurement range of the light quantity reduction amount is 20 μm, the measurement point S5 is outside the measurement range, and the measurement value of the light quantity reduction amount cannot be obtained.

  Similarly, in FIG. 23 (b), it is estimated that there is a position where the droplet passes through the optical axis with the largest amount of laser light between the measurement point S1 and the measurement point S2. In addition, it is estimated that the vicinity of the measurement point S1.

<First example of data processing method>
First, a first example of a data processing method for obtaining the position when a droplet passes through the optical axis with the largest amount of laser light from the measurement values shown in FIG. 23 will be described.

  In the first example of the data processing method, first, among the measurement points, the measurement point having the largest light amount reduction amount is obtained. Next, each of the two measurement points before and after the measurement point with the largest light quantity reduction amount obtained is set as a calculation target. At that time, if some measurement points are out of the measurement range and cannot be measured, only the measurement points at which the measurement values can be obtained are subject to calculation.

  For example, in FIG. 23B, the measurement point with the largest light amount reduction amount is the measurement point S1, and the measurement points S2, S3, S4, and S5, which are the two measurement points before and after the measurement point, are calculated. . In FIG. 23A, since the measurement point S5 is out of the measurement range and a measurement value cannot be obtained, the measurement points S2 to S4 at which the measurement value can be obtained are set as calculation objects.

  Hereinafter, in the coordinate system shown in FIG. 23, the measurement values (coordinate values of the voltage value IS) at the measurement points S1 to S5 are represented by IS1 to IS5, and the positions of the measurement points S1 to S5 (the relative positions of the print head 160 and the optical system). XS coordinate values) are represented by XS1 to XS5.

  First, when all the measurement values IS1 to IS5 can be obtained for the five measurement points S1 to S5, an interpolation function represented by the following equation 1 is used. The coefficients a, b, c, and d of this interpolation function are obtained from the positions XS1 to XS5 of the measurement points S1 to S5 and the measurement values IS1 to IS5 by the least square method.

  Next, the obtained equation (1) is differentiated to obtain the following equation (2).

  Therefore, in the equation (2), two XS solutions with IS ′ = 0 are obtained, and the XS, which is a real number and closer to the value of XS1, is the optical axis in which the droplet has the largest amount of laser light. The position that passes through.

  If both of the obtained XS solutions are imaginary numbers, or if the value of XS1 is not between XS2 and XS3, the selection of the measurement point is inappropriate or the discharge from the nozzle is extremely Since there is a high possibility of being unstable, the display means (not shown) of the droplet measuring device indicates that “the solution of XS has become an imaginary number” or “the value of XS1 is not between XS2 and XS3”. XS1 is the position where the droplet passes through the optical axis with the largest amount of laser light.

  Further, when the measurement values IS1 to IS4 can be obtained for the measurement points S1 to S4, or when the measurement values IS1 to IS3 can be obtained for the measurement points S1 to S3, the following equation (3) is used. Use the interpolation function shown. The coefficients b, c, d of this interpolation function are the minimum two from the positions XS1 to XS4 and the measured values IS1 to IS4 of the measurement points S1 to S4, or from the positions XS1 to XS3 and the measured values IS1 to IS3 of the measurement points S1 to S3. Obtained by multiplication.

  Next, the obtained equation (3) is differentiated to obtain the following equation (4).

  Therefore, in Equation (4), a solution of XS where IS ′ = 0 is obtained, and the value of XS is set as a position where the droplet passes through the optical axis with the largest amount of laser light.

  If b = 0, or if the value of XS1 is not between XS2 and XS3, there is a possibility that the selection of the measurement point is inappropriate or the ejection from the nozzle is extremely unstable. Since it is high, the display means (not shown) of the droplet measuring device indicates that “b = 0” or “the value of XS1 is not between XS2 and XS3”, and the droplet of XS1 is a laser. The position passes through the optical axis with the largest amount of light.

  If measurement values can be obtained only for the measurement points S1 and S2, let XS1 be a position where the droplet passes through the optical axis with the largest amount of laser light.

<Second example of data processing method>
Next, a second example of the data processing method improved from the first example of the data processing method will be described.

  In the second example of the data processing method, by optimizing the measurement points to be calculated among the measurement values shown in FIG. 23, the droplets have the largest amount of laser light than the first example of the data processing method. The estimated value of the position passing through many optical axes is obtained accurately.

  Specifically, first, it is determined which of the following relational expressions is satisfied for the measurement values IS1, IS2, IS3 and the positions XS1, XS2, XS3 of the measurement points S1, S2, S3 as shown in FIG. . Here, | XS1-XS2 | indicates the absolute value of the difference between XS1 and XS2, and | XS2-XS3 | indicates the absolute value of the difference between XS2 and XS3.

  Therefore, in the case where the formula 5 is satisfied, when the measurement values can be obtained for the measurement points S1 to S5 (FIG. 23B), the formula 1 and the formula 2 are used. The position at which the droplet passes through the optical axis with the largest amount of laser light is obtained by the method described in the first example.

  Here, as shown in FIG. 23 (b), the equation of Equation 5 is such that the slope of a straight line (indicated by a dotted line in the figure) connecting the measurement point S1 and the measurement point S2 is the measurement point S2 and the measurement point. The condition is larger than the slope of the straight line connecting S3 (indicated by a dotted line in the figure). Under this condition, as shown in FIG. 23B, the measurement point S2 and the measurement point S3, and the measurement point S4 and the measurement point S5 are arranged substantially symmetrically with respect to the measurement point S1. Therefore, the position where the droplet passes through the optical axis with the largest amount of laser light can be obtained with high accuracy by calculating the measurement points S1 to S5 using the positions XS1 to XS5 with all the measurement values IS1 to IS5. Can do.

  On the other hand, when the measured values S1 to S4 can be obtained when the formula 6 is satisfied (FIG. 23 (a)), or the measured values S1 to S5 are measured when the formula 6 is satisfied. Can be obtained, the droplet passes through the optical axis with the largest amount of laser light by the calculation method described in the first example using the above equation 3 and the above equation 4. Find the position.

  Here, as shown in FIG. 23 (a), Equation 6 is a condition in which the slope of the straight line connecting the measurement point S1 and the measurement point S2 is smaller than the slope of the straight line connecting the measurement point S2 and the measurement point S3. Or it shows an equal condition. Under this condition, as shown in FIG. 23A, when the measurement values can be obtained for the measurement points S1 to S4, the position where the droplet passes through the optical axis with the largest amount of laser light is estimated. With respect to the value, the measurement point S1 and the measurement point S2, and the measurement point S3 and the measurement point S4 are arranged at substantially symmetrical positions.

  Therefore, by calculating using the measurement values IS1 to IS4 and the positions XS1 to XS4 for the measurement points S1 to S4, it is possible to accurately obtain the position where the droplet passes through the optical axis with the largest amount of laser light. .

  In addition, under the condition that satisfies the expression (6), as shown in FIG. 24, when the measurement values can be obtained for the measurement points S1 to S5, similarly, the droplet is the light having the largest amount of laser light. The measurement point S1 and the measurement point S2, and the measurement point S3 and the measurement point S4 are arranged at substantially symmetrical positions around the estimated value of the position passing through the axis.

  Therefore, in this case, the measurement point S5 out of the measurement points S1 to S5 is excluded from the calculation target, and calculation is performed using the measurement values IS1 to IS4 and the positions XS1 to XS4 for the measurement points S1 to S4. The position where the droplet passes through the optical axis with the largest amount of laser light can be obtained with high accuracy.

  When the measurement values S1 to S4 can be obtained when the formula 5 is satisfied, the measurement point S4 is also included in the calculation target, and the measurement values IS1 to IS4 and the positions at the measurement points S1 to S4. From XS <b> 1 to XS <b> 4, the position at which the droplet passes through the optical axis with the largest amount of laser light is obtained by the calculation method described in the first example using the above formula 3 and the above formula 4.

  Further, when measurement values can be obtained for the measurement points S1 to S3, the measurement point S3 is also included in the calculation object regardless of whether the formula 5 or 6 is satisfied, and the measurement point S1. From the measured values IS1 to IS3 and the positions XS1 to XS3 in ~ S3, the droplet has the most light amount of the laser light by the calculation method described in the first example using the above formula 3 and the above formula 4. Find the position that passes through many optical axes.

  If measurement values can be obtained only for the measurement points S1 and S2, let XS1 be a position where the droplet passes through the optical axis with the largest amount of laser light.

  In this way, by appropriately selecting the measurement points to be calculated among the plurality of measurement points, by optimizing the measurement points used for the calculation of the interpolation function to the measurement points arranged as symmetrically as possible, The accuracy can be improved in the calculation for obtaining the estimated value of the position where the droplet passes through the optical axis with the largest amount of laser light.

  As described above, in the second example of the data processing method, optimization and measurement of measurement points to be calculated are performed for a plurality of high-order measurement points having a large measurement value based on the relationship between the magnitude and position of the measurement value. By selecting the order of the interpolation function to be used, the calculation accuracy can be improved.

  In addition, the structure which combined the structure of the droplet measuring apparatus 7 of Example 7 and the structure of the droplet measuring apparatuses 1-4 of Examples 1-4 is also considered.

  In the seventh embodiment, in describing a specific data processing method regarding the method of measuring the position of a droplet, the droplet is detected by an optical sensor using optical means using laser light, and the characteristics of the droplet are detected. However, the data processing method described in the seventh embodiment is not limited to this device. For example, the capacitance between the two electrodes when a droplet adheres between the electrodes can be measured. The present invention can also be applied to an apparatus that detects a droplet using a detection unit that detects the droplet and detects the droplet characteristic.

  According to the seventh embodiment, while the relative position between the print head 160 and the optical system is changed, the light amount decrease amount due to the passage of the droplet is detected by the photodiode 60 at each position, and the light amount decrease detected at each position. The position of the droplet can be calculated from the quantity.

  In addition, since the position of the droplet is obtained by using an interpolation function in which the measurement is performed with a small number of measurement points and the coefficient is obtained by the least square method, the measurement time can be greatly shortened.

  Also, when calculating the interpolation function, the measurement points arranged symmetrically around the estimated value (position where it is estimated that there is a solution) of the position where the droplet passes the optical axis with the largest amount of laser light. Since the calculation is performed, the calculation accuracy of the position of the droplet by interpolation can be improved.

[Configuration of inkjet recording apparatus]
Next, an ink jet recording apparatus as a specific application example of the above-described droplet measuring apparatus (1 to 7) will be described. In the case of this application example, the above-described droplet measuring devices (1 to 7) are installed in the print head units 112K, 112C, 112M, and 112Y described later. In addition to the application example, the above-described droplet measuring devices (1 to 7) may be applied as an independent device separate from the ink jet recording device, and may be applied as one component device of the ink jet recording system.

  FIG. 25 is an overall configuration diagram of the ink jet recording apparatus. As shown in the figure, the ink jet recording apparatus 110 includes a plurality of print head units 112K provided corresponding to black (K), cyan (C), magenta (M), and yellow (Y) inks. A printing unit 112 having 112C, 112M, and 112Y, an ink storage / loading unit 114 that stores ink to be supplied to each print head unit 112K, 112C, 112M, and 112Y, and a paper feeding unit 118 that supplies recording paper 116 And a decurling unit 120 for removing curl of the recording paper 116 and a nozzle surface (ink ejection surface) of the printing unit 112, and the recording paper 116 is conveyed while maintaining the flatness of the recording paper 116. A belt conveyance unit 122 that performs printing, a print detection unit 124 that reads a printing result by the printing unit 112, and a recorded recording paper (printed material). And a discharge unit 126 for discharging the parts.

  The ink storage / loading unit 114 includes ink tanks that store inks of colors corresponding to the respective print head units 112K, 112C, 112M, and 112Y, and each tank is connected to the print head units 112K, 112C via a required pipe line. , 112M, 112Y.

  Further, the ink storage / loading unit 114 includes notifying means (display means, warning sound generating means) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. ing.

  In FIG. 25, a roll paper (continuous paper) magazine is shown as an example of the paper supply unit 118, but a plurality of magazines having different paper widths, paper quality, and the like may be provided side by side. Further, instead of the roll paper magazine or in combination therewith, the paper may be supplied by a cassette in which cut papers are stacked and loaded.

  The recording paper 116 delivered from the paper supply unit 118 retains curl due to having been loaded in the magazine. In order to remove this curl, the decurling unit 120 applies heat to the recording paper 116 by the heating drum 130 in the direction opposite to the curl direction of the magazine.

  In the case of an apparatus configuration using roll paper, a cutter (first cutter) 128 is provided as shown in FIG. 25, and the roll paper is cut into a desired size by the cutter 128. Note that the cutter 128 is not necessary when cut paper is used.

  After the decurling process, the cut recording paper 116 is sent to the belt conveyance unit 122. The belt conveyance unit 122 has a structure in which an endless belt 133 is wound between rollers 131 and 132, and at least portions facing the nozzle surface of the printing unit 112 and the sensor surface of the printing detection unit 124 are horizontal (flat). Surface).

  The belt 133 has a width that is greater than the width of the recording paper 116, and a plurality of suction holes (not shown) are formed on the belt surface. As shown in FIG. 25, an adsorption chamber 134 is provided at a position facing the nozzle surface of the print unit 112 and the sensor surface of the print detection unit 124 inside the belt 133 that is stretched between the rollers 131 and 132. The recording paper 116 is sucked and held on the belt 133 by sucking the suction chamber 134 with a fan 135 to a negative pressure. In place of the suction adsorption method, an electrostatic adsorption method may be adopted.

  When the power of the motor (reference numeral 188 in FIG. 30) is transmitted to at least one of the rollers 131 and 132 around which the belt 133 is wound, the belt 133 is driven in the clockwise direction in FIG. The held recording paper 116 is conveyed from left to right in FIG.

  Since ink adheres to the belt 133 when a borderless print or the like is printed, the belt cleaning unit 136 is provided at a predetermined position outside the belt 133 (an appropriate position other than the print region).

  A heating fan 140 is provided on the upstream side of the printing unit 112 on the paper conveyance path formed by the belt conveyance unit 122. The heating fan 140 heats the recording paper 116 by blowing heated air onto the recording paper 116 before printing. Heating the recording paper 116 immediately before printing makes it easier for the ink to dry after landing.

  Each print head unit 112K, 112C, 112M, 112Y of the printing unit 112 has a length corresponding to the maximum paper width of the recording paper 116 targeted by the inkjet recording apparatus 110, and the nozzle surface has a maximum size covering. This is a full-line head in which a plurality of ink ejection nozzles are arranged over a length exceeding at least one side of the recording medium (full width of the drawable range) (see FIG. 26). As described above, each print head unit 112K, 112C, 112M, 112Y has a detection means for detecting the volume, velocity, and position of ink (droplet), and a laser beam in a predetermined shape for detection. Droplet measuring devices (1-6) equipped with optical means for forming and the like are installed.

  The print head units 112K, 112C, 112M, and 112Y are arranged in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side along the feeding direction of the recording paper 116, respectively. The print head units 112K, 112C, 112M, and 112Y are fixedly installed so as to extend along a direction substantially orthogonal to the conveyance direction of the recording paper 116.

  A color image can be formed on the recording paper 116 by discharging different color inks from the respective print head units 112K, 112C, 112M, and 112Y while conveying the recording paper 116 by the belt conveyance unit 122.

  As described above, according to the configuration in which the full-line type print head units 112K, 112C, 112M, and 112Y having nozzle rows that cover the entire width of the paper are provided for each color, the recording paper 116 and the paper 116 in the paper feed direction (sub-scanning direction) An image can be recorded on the entire surface of the recording paper 116 by performing the operation of relatively moving the printing unit 112 once (that is, by one sub-scan). Thereby, it is possible to perform high-speed printing as compared with a shuttle type head in which the head reciprocates in a direction orthogonal to the paper conveyance direction, and productivity can be improved.

  In this example, the configuration of KCMY standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink, dark ink, and special color ink are used as necessary. May be added. For example, it is possible to add an ink jet head that discharges light ink such as light cyan and light magenta. Also, the arrangement order of the color heads is not particularly limited.

  The print detection unit 124 shown in FIG. 25 includes an image sensor (line sensor or area sensor) for imaging the droplet ejection result of the printing unit 112, and clogging of nozzles or the like from the droplet ejection image read by the image sensor. It functions as a means for checking ejection characteristics such as landing position errors.

  For the print detection unit 124 of this example, a CCD area sensor in which a plurality of light receiving elements (photoelectric conversion elements) are two-dimensionally arranged on the light receiving surface can be suitably used. It is assumed that the area sensor has an imaging range in which the entire area of the ink ejection width (image recording width) by each of the print head units 112K, 112C, 112M, and 112Y can be imaged.

Also, a line sensor can be used instead of the area sensor. In this case, the line sensor includes at least each print head unit 112K, 112C, 112M, 112Y.
A configuration having a light receiving element array (photoelectric conversion element array) wider than the ink ejection width (image recording width) by the above is preferable. Test patterns or practical images printed by the print head units 112K, 112C, 112M, and 112Y of the respective colors are read by the print detection unit 124, and ejection determination of each head is performed. The ejection determination includes the presence / absence of ejection, measurement of dot size, measurement of dot landing position, and the like.

  A post-drying unit 142 is provided following the print detection unit 124. The post-drying unit 142 is means for drying the printed image surface, and for example, a heating fan is used.

  A heating / pressurizing unit 144 is provided following the post-drying unit 142. The heating / pressurizing unit 144 is a means for controlling the glossiness of the image surface, and pressurizes with a pressure roller 145 having a predetermined uneven surface shape while heating the image surface, and transfers the uneven shape to the image surface. To do.

  The printed matter generated in this manner is outputted from the paper output unit 126. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. The ink jet recording apparatus 110 is provided with a sorting means (not shown) that switches the paper discharge path in order to select the prints of the main image and the prints of the test print and send them to the discharge units 126A and 126B. Yes. Note that when the main image and the test print are simultaneously formed in parallel on a large sheet, the test print portion is separated by the cutter (second cutter) 148.

[Print head unit structure]
Next, the structure of the print head unit will be described. Since the print head units 112K, 112C, 112M, and 112Y for each color have the same structure, the print head unit is indicated by reference numeral 150 as a representative of them.

  The print head unit 150 includes a print head 160 as an ejection unit that ejects ink. FIG. 27A is a plan perspective view showing a structural example of the print head 160, and FIG. 27B is an enlarged view of a part thereof. FIG. 27C is a plan perspective view showing another structural example of the print head unit 150, and FIG. 28 shows a three-dimensional configuration of one droplet discharge element (an ink chamber unit corresponding to one nozzle 151). It is sectional drawing (sectional drawing in alignment with line 28-28 in Fig.27 (a)).

In order to increase the dot pitch printed on the recording paper 116, it is necessary to increase the nozzle pitch in the print head 160. As shown in FIGS. 27A and 27B, the print head 160 of this example includes a plurality of ink chamber units 153 including nozzles 151 serving as ink discharge ports, pressure chambers 152 corresponding to the nozzles 151, and the like. Are arranged in a zigzag matrix (two-dimensionally), so that a substantial nozzle interval projected along the head longitudinal direction (direction perpendicular to the paper feed direction) ( High density of projection nozzle pitch) has been achieved.

  The configuration in which one or more nozzle rows are formed over a length corresponding to the entire width of the recording paper 116 in a direction substantially orthogonal to the feeding direction of the recording paper 116 is not limited to this example. For example, instead of the configuration of FIG. 27A, as shown in FIG. 27C, short head modules 150 ′ in which a plurality of nozzles 151 are two-dimensionally arranged are arranged in a staggered manner and connected. A line head having a nozzle row having a length corresponding to the entire width of the recording paper 116 may be configured.

  The pressure chamber 152 provided corresponding to each nozzle 151 has a substantially square planar shape (see FIGS. 27A and 27B), and the nozzle 151 is provided at one of the diagonal corners. And a supply port 154 that is an inflow port for the supply ink. The shape of the pressure chamber 152 is not limited to this example, and the planar shape may have various forms such as a quadrangle (rhombus, rectangle, etc.), a pentagon, a hexagon, other polygons, a circle, and an ellipse.

  The ink chamber unit 153 includes a supply port 154, a pressure chamber 152, a nozzle 151, a pressure plate 156, an individual electrode 157, an actuator 158, and the like. The pressure chambers 152 of the plurality of ink chamber units 153 communicate with the common channel 155. As shown in FIG. 28, each pressure chamber 152 communicates with the common flow path 155 via the supply port 154. The common channel 155 communicates with an ink tank as an ink supply source, and the ink supplied from the ink tank is distributed and supplied to each pressure chamber 152 via the common channel 155.

  An actuator 158 having an individual electrode 157 is joined to a pressure plate (vibrating plate also serving as a common electrode) 156 constituting a part of the pressure chamber 152 (the top surface in FIG. 28). By applying a driving voltage between the individual electrode 157 and the common electrode, the actuator 158 is deformed to change the volume of the pressure chamber 152, and ink is ejected from the nozzle 151 due to the pressure change accompanying this. For the actuator 158, a piezoelectric element using a piezoelectric body such as lead zirconate titanate or barium titanate is preferably used. When the displacement of the actuator 158 returns to its original state after ink ejection, new ink is refilled into the pressure chamber 152 from the common flow path 155 through the supply port 154.

  As shown in FIG. 29, the ink chamber units 153 having the above-described structure are arranged in a constant arrangement pattern along the row direction along the main scanning direction and the oblique column direction having a constant angle θ not orthogonal to the main scanning direction. The high-density nozzle head of this example is realized by arranging a large number in a lattice pattern.

  That is, with a structure in which a plurality of ink chamber units 153 are arranged at a constant pitch D along the direction of an angle θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to be aligned in the main scanning direction is D × cos θ. Thus, in the main scanning direction, each nozzle 151 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle configuration in which 2400 nozzle rows are projected per inch (2400 nozzles / inch) so as to be aligned in the main scanning direction.

  When the nozzles are driven by a full line head having a nozzle row having a length corresponding to the entire printable width, (1) all the nozzles are driven simultaneously, (2) the nozzles are sequentially moved from one side to the other. (3) The nozzles are divided into blocks, and the nozzles are sequentially driven from one side to the other for each block, etc., and one line (1 in the width direction of the paper (direction perpendicular to the paper conveyance direction)) Driving a nozzle that prints a line of dots in a row or a line consisting of dots in a plurality of rows is defined as main scanning.

  In particular, when driving the nozzles 151 arranged in a matrix as shown in FIG. 29, the main scanning as described in the above (3) is preferable. That is, nozzles 151-11, 151-12, 151-13, 151-14, 151-15, 151-16 are made into one block (other nozzles 151-21,..., 151-26 are made into one block, Nozzles 151-31,..., 151-36 as one block,..., And by sequentially driving the nozzles 151-11, 151-12,. One line is printed in the width direction of 116.

  On the other hand, by relatively moving the above-mentioned full line head and the paper, printing of one line (a line formed by one line of dots or a line composed of a plurality of lines) formed by the above-described main scanning is repeatedly performed. This is defined as sub-scanning.

  The direction indicated by one line (or the longitudinal direction of the belt-like region) recorded by the main scanning is referred to as a main scanning direction, and the direction in which the sub scanning is performed is referred to as a sub scanning direction. In other words, in the present embodiment, the conveyance direction of the recording paper 116 is the sub-scanning direction, and the direction orthogonal to it is the main scanning direction.

  In implementing the present invention, the nozzle arrangement structure is not limited to the illustrated example. In this embodiment, a method of ejecting ink droplets by deformation of an actuator 158 typified by a piezo element (piezoelectric element) is adopted. However, the method of ejecting ink is not particularly limited in implementing the present invention. Instead of the piezo jet method, various methods such as a thermal jet method in which ink is heated by a heating element such as a heater to generate bubbles and ink droplets are ejected by the pressure can be applied.

[Explanation of control system]
FIG. 30 is a block diagram illustrating a system configuration of the inkjet recording apparatus 110. As shown in the figure, the inkjet recording apparatus 110 includes a communication interface 170, a system controller 172, an image memory 174, a motor driver 176, a heater driver 178, a print control unit 180, an image buffer memory 182, a head driver 184, and the like. ing.

  The communication interface 170 is an interface unit (image input unit) that functions as an image input unit that receives image data sent from the host computer 186. As the communication interface 170, a serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted.

  Image data sent from the host computer 186 is taken into the inkjet recording apparatus 110 via the communication interface 170 and temporarily stored in the image memory 174. The image memory 174 is a storage unit that stores an image input via the communication interface 170, and data is read and written through the system controller 172. The image memory 174 is not limited to a memory composed of semiconductor elements, and a magnetic medium such as a hard disk may be used.

  The system controller 172 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 110 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. . That is, the system controller 172 controls each part such as the communication interface 170, the image memory 174, the motor driver 176, the heater driver 178, etc., performs communication control with the host computer 186, read / write control of the image memory 174, and the like. A control signal for controlling the motor 188 and the heater 189 of the transport system is generated.

  The image memory 174 is used as a temporary storage area for image data, and is also used as a program development area and a calculation work area for the CPU.

  The motor driver 176 is a driver (drive circuit) that drives the transport motor 188 in accordance with an instruction from the system controller 172. The heater driver 178 is a driver that drives the heater 189 such as the post-drying unit 142 in accordance with an instruction from the system controller 172.

  In accordance with the control of the system controller 172, the print control unit 180 performs various processes, corrections, and the like for generating a droplet ejection control signal from image data (multi-value input image data) in the image memory 174. In addition to functioning as a signal processing unit, the generated ink discharge data is supplied to the head driver 184 to function as a drive control unit that controls the discharge drive of the print head unit 150.

  The print control unit 180 includes an image buffer memory 182, and image data, parameters, and other data are temporarily stored in the image buffer memory 182 when image data is processed in the print control unit 180. In FIG. 30, the image buffer memory 182 is shown in a form associated with the print control unit 180, but it can also be used as the image memory 174. Also possible is an aspect in which the print controller 180 and the system controller 172 are integrated and configured with one processor.

  An outline of the flow of processing from image input to print output is as follows. Image data to be printed is input from the outside via the communication interface 170 and stored in the image memory 174. At this stage, for example, RGB multivalued image data is stored in the image memory 174.

  The print control unit 180 performs a process of converting the input RGB image data into dot data of four colors K, C, M, and Y. Thus, the dot data generated by the print control unit 180 is stored in the image buffer memory 182. The dot data for each color is converted into CMYK droplet ejection data for ejecting ink from the nozzles of the print head unit 150, and the ink ejection data to be printed is determined.

  The head driver 184 outputs a drive signal for driving the actuator 158 corresponding to each nozzle 151 of the print head unit 150 according to the print content based on the ink ejection data and the drive waveform signal given from the print control unit 180. To do. The head driver 184 may include a feedback control system for keeping the head driving condition constant.

  In this way, the drive signal output from the head driver 184 is applied to the print head unit 150, whereby ink is ejected from the corresponding nozzle 151. An image is formed on the recording paper 116 by controlling the ink ejection from the print head unit 150 in synchronization with the conveyance speed of the recording paper 116.

  As described above, the recording amount and ejection timing of ink droplets from each nozzle are controlled via the head driver 184 based on the ink ejection data and the drive signal waveform generated through the required signal processing in the print control unit 180. Is done. Thereby, a desired dot size and dot arrangement are realized.

  As described with reference to FIG. 25, the print detection unit 124 is a block including an image sensor. The print detection unit 124 reads an image printed on the recording paper 116, performs necessary signal processing, etc. Variation, optical density, etc.) and the detection result is provided to the print controller 180 and the system controller 172.

  The print control unit 180 performs various corrections to the print head unit 150 based on information obtained from the print detection unit 124 as necessary, and performs cleaning operations (nozzle recovery operation) such as preliminary ejection, suction, and wiping as necessary. ) Is performed.

  The droplet measuring apparatus and the droplet measuring method of the present invention have been described in detail above, but the present invention is not limited to the above examples, and various improvements and modifications can be made without departing from the gist of the present invention. Of course you can go.

It is a block diagram which shows the outline of the droplet measuring apparatus of Example 1, (a) is a front view, (b) is a bottom view. (A) is an output voltage waveform diagram in a photodiode, and (b) is a drive waveform diagram of droplet ejection in a print head. (A) is a relationship diagram between the amount ΔZv of moving the laser beam and the time interval ΔTv, and (b) is a relationship diagram between the time interval ΔTv and the velocity V of the droplet. The light intensity distribution of the laser beam received by the light receiving means is shown. It is a figure showing the waveform of the output signal of a light reception sensor when discharging a 1st droplet and a 2nd droplet, and a discharge drive waveform. It is a figure which shows the Gaussian beam profile (light quantity distribution of a Gaussian beam) used by simulation. It is a result figure of the simulation of the droplet position of X-axis direction, and light quantity. It is a figure which shows the verification result by simulation when a droplet amount is 20 pl and the beam width of a Z-axis direction is 40 micrometers. It is a figure which shows the verification result by simulation when a droplet amount is 20 pl and the beam width of a Z-axis direction is 60 micrometers. It is a figure which shows the verification result by simulation when the droplet amount is 2 pl and the beam width in the Z-axis direction is 40 μm. It is a figure which shows the verification result by simulation when a droplet amount is 2 pl and the beam width of a Z-axis direction is 60 micrometers. It is a figure showing a slit. It is a figure which shows the relationship between the color of a droplet and the color of a laser beam. It is a block diagram which shows the outline of the droplet measuring apparatus of Example 2, (a) is a front view, (b) is a bottom view. FIG. 6 is a configuration diagram illustrating an outline of a droplet measuring apparatus according to a third embodiment. The light intensity distribution of the laser beam received by the light receiving means is shown. (A) is a block diagram which shows the outline of the droplet measuring apparatus of Example 4, (b) (c) is an external view of a fly-eye lens. It is a block diagram which shows the outline of the droplet measuring apparatus of Example 5, (a) is a front view, (b) is a bottom view. (A)-(c) is a light intensity distribution figure of the laser beam light-received by the light-receiving means, (d) is an output voltage waveform figure in a photodiode. FIG. 6 is a relationship diagram between a maximum drop amount Ip of an output voltage waveform and a droplet position Xp. FIG. 10 is a configuration diagram illustrating an outline of a droplet measuring apparatus according to a sixth embodiment. FIG. 10 is a configuration diagram illustrating an outline of a droplet measuring apparatus according to a seventh embodiment. It is a figure which shows the result of having measured the light quantity reduction amount when the droplet discharged from the nozzle of a measuring object shields a laser beam. It is a figure which shows the result of having measured the light quantity reduction | decrease amount when a measured value can be obtained about measurement point S1-S5 when satisfy | filling Formula 6. 1 is an overall configuration diagram of an ink jet recording apparatus. FIG. 26 is a plan view of the main part around the printing unit of the inkjet recording apparatus shown in FIG. 25. It is a plane perspective view which shows the structural example of a head. It is sectional drawing which follows the 28-28 line | wire in Fig.27 (a). It is an enlarged view which shows the nozzle arrangement | sequence of a head. It is a block diagram which shows the system configuration | structure of an inkjet recording device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1-7 ... Droplet measuring apparatus, 10 ... Laser light source, 12 ... Collimator lens, 14 ... Cylindrical lens, 16 ... Spherical lens, 18 ... Slit, 20 ... Photodiode, 22 ... Droplet characteristic calculation means

Claims (24)

A first laser light source;
At a position where the laser beam from the first laser light source is irradiated to the discharged droplet, the beam cross section of the laser beam is perpendicular to the beam width in the droplet discharge direction with respect to the droplet discharge direction. A beam width in a direction is increased, and the light intensity of the laser beam is set within a predetermined range within a range in which variations in the droplet discharge position in a direction perpendicular to the droplet discharge direction occur. First optical means for receiving;
First light receiving means for receiving the laser beam irradiated to the droplet by the first optical means and generating a detection signal;
First droplet characteristic calculating means for calculating the volume and velocity of the droplet from the detection signal generated by the first light receiving means;
A droplet measuring apparatus characterized by comprising: The droplet measuring device according to claim 1.
The first optical means comprises a cylindrical lens;
A droplet measuring apparatus characterized by the above. The droplet measuring device according to claim 1.
The first optical means includes a diffusion plate for diffusing the laser beam;
A droplet measuring apparatus characterized by the above. The droplet measuring device according to claim 1.
The first optical means includes a fly-eye lens that diffuses the laser light;
A droplet measuring apparatus characterized by the above. The droplet measuring device according to any one of claims 1 to 4,
A second laser light source;
Variations in the droplet discharge position in the direction perpendicular to the droplet discharge direction with respect to the beam cross-section of the laser beam at a position where the laser beam from the second laser light source is irradiated to the discharged droplet. Second optical means for making the intensity of the laser light non-uniform within a range to be generated;
Second light receiving means for receiving the laser beam irradiated to the droplet by the second optical means and generating a detection signal;
Second droplet characteristic calculating means for calculating the position of the droplet from the detection signal generated by the second light receiving means;
A droplet measuring apparatus characterized by comprising: The droplet measuring device according to any one of claims 1 to 5,
Having light limiting means for limiting the laser light received by the first light receiving means or the second light receiving means;
A droplet measuring apparatus characterized by the above. The droplet measuring device according to any one of claims 1 to 6,
The color of the laser light emitted from the first laser light source or the color of the laser light emitted from the second laser light source is a complementary color to the color of the droplet,
A droplet measuring apparatus characterized by the above. The droplet measuring device according to claim 5.
The laser light emitted from the first laser light source and the laser light emitted from the second laser light source have different wavelengths;
A droplet measuring apparatus characterized by the above. The droplet measuring device according to claim 5.
The laser light emitted from the first laser light source and the laser light emitted from the second laser light source have different planes of polarization;
A droplet measuring apparatus characterized by the above. A range in which the droplet discharge position varies in a direction perpendicular to the droplet discharge direction with respect to the beam cross section of the laser beam at a position where the laser beam from the first laser light source is irradiated to the discharged droplet. The light intensity of the laser light within a predetermined range, receiving the laser light irradiated to the droplet, and calculating the volume and velocity of the droplet,
A method for measuring droplets. The droplet measurement method according to claim 10.
When the time change of the value of the detection signal generated by receiving the laser beam irradiated to the droplet is measured and the value of the detection signal changes by a predetermined amount from when the droplet is driven to be ejected A time interval measuring step for measuring a time interval until,
A speed calculating step of calculating the speed of the droplet from the correlation between the time interval and the speed of the droplet,
A method for measuring droplets. The droplet measurement method according to claim 10.
Measuring a time change of a value of a detection signal generated by receiving the laser beam applied to the droplet, and measuring a maximum change amount of the value of the detection signal;
A volume calculation step for calculating the volume of the droplet from the correlation between the maximum change amount and the volume of the droplet,
A method for measuring droplets. A laser light source;
The range in which the droplet ejection position varies in the direction perpendicular to the droplet ejection direction with respect to the beam cross section of the laser beam at the position where the laser beam from the laser light source is irradiated to the ejected droplet. Optical means for making the light intensity of the laser light non-uniform,
A light receiving means for receiving the laser light applied to the droplet by the optical means and generating a detection signal;
Droplet discharge position changing means for changing the relative position of the light receiving means and the droplet;
Droplet position calculating means for calculating the position of the droplet from a plurality of the detection signals generated at the relative position of the light receiving means and the droplet changed by the droplet discharge position changing means;
A droplet measuring apparatus characterized by comprising: The droplet measuring device according to claim 13.
The droplet position calculation means is an interpolation in which a coefficient is obtained from a plurality of coordinate values of the detection signals by a least square method in a coordinate system indicating a relationship between the coordinate values of the relative positions and the coordinate values of the detection signals. Calculating the position of the droplet using a function;
A droplet measuring apparatus characterized by the above. The droplet measuring device according to claim 14.
The droplet position calculation means selects one of a quadratic function and a cubic function as the interpolation function according to coordinate values of a plurality of the detection signals;
A droplet measuring apparatus characterized by the above. The droplet measuring device according to claim 15,
The coordinate values of the plurality of detection signals are set to IS1, IS2, IS3 in descending order of absolute values, and the coordinate values of the relative positions when the coordinate values IS1, IS2, IS3 of the plurality of detection signals are detected. When XS1, XS2, and XS3,
The droplet position calculation means selects a cubic function as the interpolation function when the relational expression {(IS1-IS2) / | XS1-XS2 |> (IS2-IS3) / | XS2-XS3 |} holds. , {(IS1-IS2) / | XS1-XS2 | ≦ (IS2-IS3) / | XS2-XS3 |} is selected, a quadratic function is selected as the interpolation function.
A droplet measuring apparatus characterized by the above. The droplet measuring device according to claim 16.
When the droplet position calculation means satisfies the relational expression {(IS1-IS2) / | XS1-XS2 | ≦ (IS2-IS3) / | XS2-XS3 |} and selects a quadratic function as the interpolation function When there are five coordinate values of the plurality of detection signals, the coefficient of the interpolation function is obtained by the least square method from the top four coordinate values having the largest absolute value among the coordinate values of the plurality of detection signals. thing,
A droplet measuring apparatus characterized by the above. Within the range in which the droplet discharge position varies in the direction perpendicular to the droplet discharge direction with respect to the beam cross section of the laser beam at the position where the laser beam from the laser light source is irradiated to the discharged droplet. A plurality of detection signals generated by the light receiving means by making the light intensity of the laser light non-uniform, changing the relative position of the light receiving means for receiving the laser light irradiated to the droplet and the droplet Calculating the position of the droplet from
A method for measuring droplets. Detecting means for detecting a discharged droplet and generating a detection signal;
Droplet discharge position changing means for changing the relative position of the detection means and the droplet;
Droplet position calculating means for calculating the position of the droplet from the plurality of detection signals generated at the relative positions of the detection means and the droplet changed by the droplet discharge position changing means;
A droplet measuring apparatus characterized by comprising: The droplet measuring device according to claim 19,
The droplet position calculation means is an interpolation in which a coefficient is obtained from a plurality of coordinate values of the detection signals by a least square method in a coordinate system indicating a relationship between the coordinate values of the relative positions and the coordinate values of the detection signals. Calculating the position of the droplet using a function;
A droplet measuring apparatus characterized by the above. The droplet measurement device of claim 20,
The droplet position calculating means selects and calculates either a quadratic function or a cubic function as the interpolation function in accordance with a plurality of detection signal values;
A droplet measuring apparatus characterized by the above. The droplet measurement device of claim 21,
The coordinate values of the plurality of detection signals are set to IS1, IS2, IS3 in descending order of absolute values, and the coordinate values of the relative positions when the coordinate values IS1, IS2, IS3 of the plurality of detection signals are detected. When XS1, XS2, and XS3,
The droplet position calculation means selects a third order number as the interpolation function when the relational expression {(IS1-IS2) / | XS1-XS2 |> (IS2-IS3) / | XS2-XS3 |} holds. When the relational expression {(IS1-IS2) / | XS1-XS2 | ≦ (IS2-IS3) / | XS2-XS3 |} is satisfied, a secondary number is selected as the interpolation function.
A droplet measuring apparatus characterized by the above. The droplet measuring device according to claim 22,
When the droplet position calculation means satisfies the relational expression {(IS1-IS2) / | XS1-XS2 | ≦ (IS2-IS3) / | XS2-XS3 |} and selects a quadratic function as the interpolation function When there are five coordinate values of the plurality of detection signals, the coefficient of the interpolation function is obtained by the least square method from the top four coordinate values having the largest absolute value among the coordinate values of the plurality of detection signals. thing,
A droplet measuring apparatus characterized by the above. Changing the relative position of the position of the droplet and the detection means for detecting the discharged droplet, and calculating the position of the droplet from a plurality of detection signals generated by the detection means;
A method for measuring droplets.

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