JP2008230044A - Measuring device of liquid droplet discharge head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring device which can measure the characteristic of a liquid droplet discharge head with about the same precision as in the case where a predetermined pattern is printed in a recording medium such as a paper, etc. without using a printing medium such a paper, etc. <P>SOLUTION: An illumination light is projected from the direction which crosses the flight direction of the liquid droplet discharged from an inspection head, and the scattered light of the illumination light generated by the liquid droplet is focused on an imaging element from the position where no illumination light enters, and then the characteristic of the head to be inspected is made to be measured from the image of the scattered light made by the liquid droplet. Using an element of accumulation type which outputs signals such as a voltage, a current, etc. according to the added-up light amount of the incident light for a predetermined time, as the imaging element, the liquid droplet is made to be discharged from two or more nozzles during the accumulation time of the imaging element. When discharging the liquid droplet from two or more nozzles of the head to be inspected, the liquid droplet is made to be discharged while moving the head to be inspected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a measurement device for a droplet discharge head such as an inkjet head, and more particularly to a measurement device for a droplet discharge head that determines characteristics of a droplet discharge head from droplets discharged from a nozzle.

  Conventionally, inspecting a droplet discharge head such as a head of an ink jet printer has been performed by printing a predetermined inspection pattern on a recording medium such as paper as disclosed in Japanese Patent Application No. 03039707. When the inspection is performed automatically, a recording medium supply / discharge mechanism is required, which increases the cost of the apparatus and lowers the operating rate of the inspection apparatus.

  For this reason, as a first method that does not use a recording medium, as disclosed in Japanese Patent Laid-Open No. 2001-150696, light is projected and received so as to sandwich an ink droplet in flight, and an image of the ink droplet is captured. A method for measuring the position and velocity of ink droplets has been proposed.

As a second method, as disclosed in Japanese Patent Application Laid-Open No. 8-281950, focused light is applied to discharged water droplets, and the quality of the head is determined based on the correlation between the reflected light and the discharge signal. Proposed.
Special registration 03039707 Japanese Patent Laid-Open No. 2001-150696 JP-A-8-281950

  However, in the case of the first conventional method, since light is projected and received so as to sandwich the ink droplet, if a light source that is continuously lit is used, the illumination light is received when the ink droplet is not within the measurement range. As a result, the contrast between the image of the droplet and the surroundings is reduced, and a flash light source such as a strobe is required.This complicates the device and increases the cost of the device. The discharge pattern is limited, and the average characteristics when droplets are discharged at a high repetition frequency cannot be measured. For example, it is impossible to make a precise determination as a predetermined pattern is printed on a recording medium such as paper for inspection. There was a problem.

  In the case of the second conventional method, the focused light is applied to the ejected water droplets, and the head characteristics resulting from the ejection speed of the water droplets are measured from the correlation between the reflected light and the ejection signal, and the quality of the head is determined. Therefore, it is difficult to evaluate the characteristics caused by the discharge direction, etc., and it is difficult to measure a plurality of water droplets at the same time, so the more accurate the judgment is made by printing a predetermined pattern on a recording medium such as paper. There was a problem that could not.

  An object of the present invention is to provide a measuring apparatus capable of measuring the characteristics of a droplet discharge head with the same degree of accuracy as when a predetermined pattern is printed on a recording medium such as paper without using a printing medium such as paper. It is in.

  In order to achieve the above object, the illumination light is projected from the direction intersecting the flight direction of the droplet ejected from the head to be inspected, and the scattered light of the illumination light from the droplet is imaged from the position where the illumination light does not enter. An image is formed on the element, and the characteristics of the head to be inspected are measured from the image of the scattered light from the droplet.

  As the image sensor, a storage-type element that outputs a signal such as a voltage or current corresponding to the integrated light quantity of light incident at a predetermined time is used, and droplets are ejected from a plurality of nozzles during the image sensor's accumulation time. It was made to do.

  When ejecting droplets from a plurality of nozzles of the head to be inspected, the droplets are ejected while moving the head to be inspected.

  In the above configuration, the scattered light of the illumination light projected from the direction intersecting the flight direction of the droplet ejected from the head to be inspected is received from the position where the illumination light does not enter. Only scattered light is imaged, and droplets can be detected without using a flash light source such as a strobe.

  Since droplets are ejected from a plurality of nozzles during the accumulation time of the image sensor, a plurality of droplet images can be obtained on one screen, so that the measurement time can be shortened.

  Since the liquid droplets are ejected while moving the head to be inspected, it is possible to image a two-dimensional inspection pattern, and the liquid can be obtained with the same accuracy as when a predetermined pattern is printed on a recording medium such as paper. The characteristics of the droplet discharge head can be measured.

  As described above, the illumination light is projected from the direction intersecting the flight direction of the droplet ejected from the head to be inspected, and the scattered light of the illumination light from the droplet is projected on the image sensor from the position where the illumination light does not enter. Since only the scattered light from the droplet is imaged, the droplet can be detected without using a flash light source such as a strobe.

  As the image sensor, a storage-type element that outputs a signal such as a voltage or current corresponding to the integrated light quantity of light incident at a predetermined time is used, and droplets are ejected from a plurality of nozzles during the image sensor's accumulation time. Thus, since a plurality of droplet images can be obtained on one screen, the measurement time can be shortened.

  When droplets are ejected from a plurality of nozzles of the head to be inspected, the droplets are ejected while moving the head to be inspected, so that it is possible to image a two-dimensional inspection pattern and record on paper, etc. The same measurement as when a predetermined pattern is printed on the medium is possible, and the characteristics of the droplet discharge head can be measured with high accuracy.

  Thus, according to the present invention, it is possible to provide a measurement apparatus for a droplet discharge head that can measure the image characteristics of the droplet discharge head without using a print medium such as paper.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram for explaining the configuration of a first embodiment of a droplet discharge head inspection apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a head to be inspected, and two nozzle rows in which a plurality of ink ejection nozzles are arranged in the depth direction on the drawing are arranged in the horizontal direction on the drawing. Reference numeral 2 denotes ink droplets ejected from the head 1 to be inspected. Reference numeral 10 denotes an illuminating device, which is arranged so that it can illuminate so as to intersect the flight direction of the ink droplet 2. Illumination light 11 is obliquely emitted from the illumination device 10 and has a width capable of collectively illuminating ink droplets ejected from a plurality of nozzles, and has a thin sheet-like beam shape in the direction of ink droplet flight. I am doing. Further, when the head to be inspected is mounted on a printer or the like, the illumination light 11 is arranged to pass through a position where a print medium such as paper is arranged. Reference numeral 12 denotes an imaging lens for forming an image of the ink droplet 2, and when the head to be inspected is mounted on a printer or the like, it is adjusted so that the print medium such as paper is in focus. Has been. The imaging lens 12 is disposed at a position slightly deviated from the flight path of the ink droplet 2 in order to prevent the imaging lens 12 from being soiled by the ink droplet 2. An image sensor 13 converts an optical image of the ink droplet 2 imaged by the imaging lens 12 into an electric signal. A plurality of light receiving elements are two-dimensionally arranged, and the integrated light quantity incident during a predetermined time is obtained. For example, a CCD area sensor or a MOS area sensor that outputs a proportional voltage or signal. Reference numeral 15 denotes a control device that gives an ejection signal for ejecting ink droplets to the head 1 to be inspected, controls the lighting device 10 to be turned on / off, adjusts the amount of light, and controls the driving and timing of the head 1 to be inspected. The image of the ink droplet 2 is input and analyzed while measuring, and the characteristic value of the head 1 to be inspected is calculated. FIG. 2 is a diagram for explaining how an image of the ink droplet 2 is captured. FIG. 2A shows a state in which the ink droplet 2 ejected from the head to be inspected 1 has not reached the position of the illumination light 11. In this state, there is no light incident on the imaging lens 12, and the entire surface is completely covered. The image becomes dark. FIG. 2B shows a state in which the ink droplet 2 ejected from the head 1 to be inspected is passing through the illumination light 11. At this time, the illumination light 11 is scattered by the ink droplet 2, and a part of it is condensed. The light enters the image lens 12 and forms an image on the light receiving surface of the image sensor 13. Here, since the light incident on the imaging lens 12 is only scattered light from the ink droplet 2 of the illumination light 11, it is not necessary to use a flash light source such as a strobe for the illumination device 10, and a continuous lighting light source may be used. If the ink droplets 2 are ejected from the plurality of nozzles of the head 1 to be inspected during the accumulation time of the image sensor, an image having a plurality of ink droplet images on one screen as shown in FIG. 3 is obtained. In FIG. 3, reference numeral 20 denotes a background portion, which is dark because no light enters from the background portion. 21 is an image of scattered light from the ink droplets 2 ejected by a plurality of nozzles, and this portion becomes a bright luminescent spot, and only the portion where the plurality of ink droplets 2 have passed the illumination light 11 is bright as the entire image. It becomes an image.

  Next, a non-ejection detection method will be described with reference to FIG. In the droplet image of FIG. 3 obtained by the above-described configuration, a region brighter than a predetermined threshold is extracted as a droplet candidate, and a liquid having an area within a predetermined range among the droplet candidates is ejected. If the number of droplet areas is counted and compared with the number of droplets (or the number of nozzles) that should be ejected, the number of nozzles that have not ejected (no droplets ejected) can be counted. For example, the predetermined threshold value is determined from T = K · (Imax−Imin) + Imin (where 0 <K <1) by obtaining the maximum luminance value Imax and the minimum luminance value Imin in the screen. Stable measurement is possible without being affected by fluctuations in the amount of light. The background portion may be determined from T = K · Imax (where 0 <K <1), considering that almost no light is incident, or determined using a discrimination threshold method or the like. May be.

  Next, a method for measuring the droplet landing position accuracy will be described with reference to FIG. In order to measure the landing position accuracy of the droplet, each center position of the droplet region in FIG. 3 is calculated, and the landing position accuracy is obtained from the center position data. FIG. 4 is a diagram for explaining a method of measuring the landing position accuracy. In FIG. 4, 21L1 to 9 and 21R1 to 9 are regions of liquid droplets ejected from different nozzles, and “+” marks are included therein. Represents the center position of each droplet region. In the drawing, the coordinate system has a horizontal direction in the drawing as an X-axis (head scanning) direction and a vertical direction as a Y-axis (nozzle alignment) direction. First, as described above, a droplet region is extracted from the image of FIG. 3 on the basis of brightness, and the center position is obtained for each droplet region. Next, it is separated into two groups based on the X coordinate value of the obtained center position. In FIG. 4, 21L1 to 9L are divided into a left column and 21R1 to 9R are divided into a right column. Next, for each group, the average value of the X coordinate values of the center position of the droplet region is determined as follows, and is set as XLave and XRave, respectively.

XLave = (XL (1) + XL (2) +... + XL (n)) / n
XRave = (XR (1) + XR (2) +... + XR (m)) / m
However, XL (k), XR (k): X coordinate value of the center position of the kth droplet region in the left and right columns
m, n: number of regions (in FIG. 4, m = n = 9)
Here, when L = ‖XRave−XLave‖ is obtained and compared with the interval between the nozzle rows in the head to be inspected, whether the droplets ejected from the nozzles are ejected in parallel or are opened outward and ejected? Or whether it is discharged inside. Further, if the difference between the X coordinate value of the center position and the average value of the X coordinate values of the center position is obtained for each column, the accuracy of the landing position of each droplet in the X direction can be evaluated. That is,
dXL (i) = XL (i) -XLave (i = 1 to n)
dXR (j) = XR (j) −XRave (j = 1 to m)
What is necessary is just to calculate the maximum / minimum value, standard deviation, etc. In addition, regarding the landing position accuracy in the Y direction, it is only necessary to obtain a difference between the Y coordinates of adjacent areas in each column. That is,
PL (i) = YL (i + 1) −YL (i) (i = 1 to n−1)
PR (j) = YR (j + 1) −YR (j) (j = 1 to m−1)
If the average value, maximum / minimum value, standard deviation, etc. are calculated for PL and PR, the landing position accuracy in the Y-axis direction can be evaluated.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 5 is a diagram for explaining the configuration of the second embodiment. In the figure, the same components as those in FIG. In FIG. 5, reference numeral 5 denotes a carriage that holds the head 1 to be inspected and supplies an ejection signal from the control device to the head 1 to be inspected. Reference numeral 6 denotes a stage, to which the carriage 5 is fixed, and moves the head 1 to be inspected by scanning. Reference numeral 14 denotes a TV camera incorporating a CCD image sensor and the like, which receives a trigger signal from the outside, receives light for a predetermined time (accumulation time), outputs a video signal corresponding to the amount of light incident during this time, and outputs the next trigger. The same video signal can be output repeatedly until the signal is received. Further, the accumulation time can be changed from the control device 15. The imaging lens 12 is arranged directly below the head 1 to be inspected, and has a structure for observing from the ejection direction of the ink droplet 2. Reference numeral 30 denotes an antifouling device using an air flow for preventing the ejected ink droplet 2 from adhering to the imaging lens 12 and becoming dirty, and sandwiches the flight path of the ink droplet 2 immediately before the imaging lens. It has a structure where air is blown from one side and sucked by the other side. Here, since the ink droplet 2 is very small and has a small mass, when it is ejected from the nozzle, the speed is lowered due to air resistance or the like, and when it is more than 30 mm away from the nozzle, it drifts although it falls by its own weight. It can be easily eliminated by airflow. If an air stream is arranged immediately before the imaging lens 12, the droplet 2 crosses in front of the imaging lens 12, but it is already greatly out of the focusing range of the imaging lens 12, so that the imaging is affected. In addition, there is almost no reduction in the amount of light due to the influence of light shielding due to the relationship between the dimensions of the imaging lens 12 and the droplet 2. In the case of the configuration of the present embodiment, the optical axis of the imaging lens 12 can be perpendicular to the scanning plane of the head 1 to be inspected, so that the in-focus range is parallel to the scanning plane of the head 1 to be inspected. If a lens system with a shallow depth of field is used, only an image near the paper position can be captured without reducing the illumination light 11 into a sheet shape.

  Next, the operation of each unit will be described with reference to FIG. In FIG. 6, the horizontal axis indicates the elapsed time. First, the control device 15 sends a stage drive pulse to the stage 6 and starts head scanning. Next, the control device 15 monitors the position of the stage 6, sends a trigger signal to the TV camera 14 before the head 1 to be inspected enters the field of view of the TV camera 14, and then passes through the carriage 5. Thus, an ejection signal is given to the head 1 to be inspected. The TV camera 14 accumulates the scattered light of the illumination light 11 by the droplet 2 while the head to be inspected 1 is ejecting while moving with the ejection signal corresponding to the predetermined inspection pattern in the field of view of the TV camera 14. is doing. When ejection of the inspection pattern is completed and the head to be inspected deviates from the field of view of the TV camera 14, accumulation of the TV camera 14 is also completed, and an image of scattered light from the droplets of the inspection pattern is repeatedly output. The control device 15 takes in this video signal, analyzes it, and calculates the characteristics of the head 1 to be inspected.

  FIG. 7 is a diagram for explaining the ejection signal in detail, and FIG. 7A is a diagram for explaining the arrangement of the ink ejection nozzles of the head 1 to be inspected. FIG. In FIG. 7 (a), N1, N2,..., Nm are the first nozzle, the second nozzle,. The two nozzles are arranged in a staggered manner that are separated by a distance Pr in the head scanning direction and shifted by a distance Pc in the nozzle arrangement direction. FIG. 7B is a diagram for explaining a case where ejection signals are simultaneously applied to odd-numbered nozzles and even-numbered nozzles. In this case, odd-numbered nozzle rows and even-numbered nozzle rows are in the head scanning direction. Since the distance Pr is apart, the droplets are ejected at different positions, and the pattern by the odd numbered nozzles and the pattern by the even numbered nozzles are shifted by the distance Pr. FIG. 7C is a diagram for explaining the case where the ejection signal is given at the timing at which the interval between the odd-numbered nozzle row and the even-numbered nozzle row is corrected, and ΔT when the scanning speed of the head to be inspected is Vp. = Pr / Vp delays the ejection signal applied to the odd-numbered nozzle row. As a result, when the odd-numbered nozzle row reaches the position of the even-numbered nozzle row, ejection is started and the pattern deviation is eliminated. When the scanning direction is reversed, the ejection signal to be given to the odd-numbered nozzle rows by ΔT = Pr / Vp may be advanced.

  Next, a measurement example of the characteristics of the head 1 to be inspected in the present embodiment will be described. FIG. 8 shows an inspection pattern by scattered light in the present embodiment. In FIG. 8, 60 is a first inspection pattern, 61 is a second inspection pattern, and 61 is a third inspection pattern. Pattern. Reference numeral 50 denotes the field of view of the TV camera 14, and the inner side is a measurement target. The first inspection pattern 60 starts ejection from outside the field of view of the TV camera 14 in consideration of fluctuations in the scanning speed of the stage 6 and the adjustment state of the field of view of the TV camera 14. 9 and 10 are examples of the first inspection pattern 60 in FIG. 8, FIG. 9 is a pattern in which ejection is performed at a frequency of 50% of continuous ejection, and FIG. 10 is similarly ejected at a frequency of 25%. It is a pattern. The patterns shown in FIGS. 9 and 10 are so-called halftone patterns, which are suitable for evaluating the uniformity of density when drawn on a printing medium such as paper. A method for measuring the characteristic value of the head to be inspected 1 using this pattern will be described with reference to FIG. FIG. 11A is a diagram showing a measurement area of the first inspection pattern, and a frame indicated by 70 is the measurement area. FIG. 11B shows the first test pattern measurement area 70 extracted from FIG. 11A, and the test pattern image data stored in the image memory (not shown) built in the control device 15. Is part of. FIG. 11C shows the average of the X direction in the figure for this image data, which is the average luminance distribution in the Y direction of the image shown in FIG. 11B. In the average luminance distribution of FIG. 11 (c), a portion brighter than the predetermined threshold value Tp is used as a pattern range, and further, the luminance is lowered due to the number of pixels at both ends of the pattern range being an end portion. The part excluding the part is the measurement range. For the measurement range, as shown in FIG. 11 (d), the average value, maximum value, minimum value, difference between the maximum value and minimum value, or standard deviation are calculated, and the density of the head 1 to be inspected is calculated. The characteristic value of uniformity may be used.

  In addition, when the droplet 2 is small and a gap is formed between the images of the droplet 2 and the background of the average luminance distribution is affected, a low-pass filter or a maximum value is calculated before and after the process of calculating the average luminance distribution. Preprocessing such as extraction processing may be performed.

  Further, the characteristic value may be calculated from data obtained by correcting the spatial frequency sensitivity of human vision instead of directly obtaining the characteristic value from the average luminance distribution.

FIG. 12 is an example of the second inspection pattern 61 in FIG. 8 and is a pattern in which nozzles are continuously discharged every three nozzles. First, the nozzles N1, N5, N9,. Continuous discharge, then nozzles N2, N6, N10, ... Continuous discharge, then nozzles N3, N7, N11, ... Continuous discharge, then nozzles N4, N8, N12, ... Continuous discharge This is a horizontal line pattern. The pattern shown in FIG. 12 is a pattern suitable for evaluating the uniformity of the landing positions of the droplets 2 in the nozzle arrangement direction when drawn on a print medium such as paper. A method for measuring the characteristic value of the head to be inspected 1 using the inspection pattern of FIG. 12 will be described with reference to FIG. FIG. 13A is a diagram showing the measurement area of the second inspection pattern, and the inside of the frame indicated by 71 is the horizontal line measurement area. This area is further divided into four areas as shown in FIG. 13B, reference numeral 71-1 denotes a first horizontal line measurement region by droplets from the nozzles N1, N5, N9,... In FIG. The second horizontal line measurement region by the droplets from N10,..., 71-3 is the third horizontal line measurement region by the droplets from nozzles N3, N7, N11,. This is a fourth horizontal line measurement region by droplets from N4, N8, N12,. FIG. 13C shows the first first horizontal line measurement region 71-1 extracted from the image. FIG. 13D shows the horizontal line image of FIG. 13C averaged in the X direction in the figure. The average luminance distribution calculated as above. In FIG. 13 (d), a portion where the average luminance distribution is brighter than a predetermined threshold value Tv is separated from the background as a horizontal line portion formed by droplets, and the Y coordinate at which the luminance is maximum in each horizontal line portion is represented by the Y ( Nozzle alignment direction. In FIG. 13D, Ym (m = 1, 5, 9,...) Is a landing position of the nozzle Nm in the Y (nozzle alignment) direction, and a difference in landing positions of droplets from adjacent nozzles. That is,
dYm = Ym + 1−Ym
The average value, maximum value, minimum value, standard deviation, and the like may be used as the characteristic value of the landing position uniformity in the nozzle arrangement direction of the head 1 to be inspected.

FIG. 14 is an example of the third inspection pattern 62 in FIG. 8, which is a vertical line pattern in which all nozzles are simultaneously ejected at a frequency of 25% of continuous ejection, and head scanning when drawing on a print medium such as paper. This pattern is suitable for evaluating the uniformity of the landing position of the droplet 2 in the direction. A method for measuring the characteristic value of the head 1 to be inspected based on the inspection pattern of FIG. 14 will be described with reference to FIG. FIG. 15A is a diagram showing a measurement region of the third inspection pattern, and a frame indicated by 72 is a vertical line measurement region. As shown in FIG. 15B, this area is further divided into four areas. In FIG. 15B, 72-1 is a first vertical line measurement region for measuring the first vertical line VL1, and 72-2 is a second vertical line measurement region for measuring the second vertical line VL2. , 72-3 is a third vertical line measurement region for measuring the third vertical line VL3, and 72-4 is a fourth vertical line measurement region for measuring the fourth vertical line VL4. FIG. 15C shows the first vertical line region 72-1 extracted from the four vertical line measurement regions. Here, the X position xc1 (ya), which is the maximum luminance of the luminance distribution in the X direction at the Y coordinate value ya of the vertical line VL1, is set as the center position at the Y coordinate value ya of the vertical line VL1, and this center position is the entire vertical line. For the center line CL of the vertical line VL1. FIG. 15D is a diagram for explaining a method for evaluating the uniformity of the landing position of the head 1 in the head scanning direction from the center line CL thus obtained. In the figure, CL is a center line obtained by the method described with reference to FIG. NL is an approximate straight line of the center line CL. When the value of the center line CL (= X coordinate value) and the value of the approximate line NL at the Y coordinate y are CL (y) and NL (y), respectively, the center line from the approximate line NL (y) CL (y) deviation amount dX (y) = CL (y) −NL (y)
, The maximum value of dX (y), the minimum value, the difference between the maximum value and the minimum value, the standard deviation, the inclination θc of the approximate straight line NL (y) and the like, and the uniformity of the landing position in the head scanning direction The characteristic value may be used.

  As described above, by measuring the density uniformity, the position uniformity in the nozzle arrangement direction, and the position uniformity in the head scanning direction, from the scattered light image of the droplet 2 discharged to the illumination light 11, the head 1 to be inspected. As the characteristic value, the image characteristic at the time of drawing can be measured.

(Third embodiment)
FIG. 16 is a diagram illustrating the configuration of the third embodiment. The same number is attached | subjected about the same thing as FIG. 1 and FIG. In the figure, reference numeral 31 denotes a transparent sheet which is disposed immediately before the imaging lens 12 and is sent from the right roll to the left roll in the drawing when the head 1 to be inspected at the time of measurement is discharging. It has become. Since the transparent sheet is disposed immediately before the imaging lens 12, the imaging lens 12 can be prevented from being contaminated by the droplet 2. Since the transparent sheet 31 hardly passes anything, it can prevent dirt with high reliability. When all the transparent sheets 31 are sent to the left roll on the drawing, they can be exchanged, cleaned outside the apparatus, and used again.

(Fourth embodiment)
FIG. 17 is a diagram illustrating the configuration of the fourth embodiment. The same components as those in FIGS. 1 and 5 are given the same numbers. In the figure, reference numeral 32 denotes a transparent plate having a rotatable structure, which is disposed immediately before the imaging lens 12 and rotates when the head 1 to be inspected at the time of measurement is discharging. ing. A cleaning device 33 for the transparent plate 32 has a suction or cleaning / drying function and cleans the ink droplets 2 attached to the transparent plate 32. Since the transparent plate 32 is disposed immediately before the imaging lens 12, the imaging lens 12 can be prevented from being contaminated by the droplet 2. Since the transparent plate 32 passes almost nothing, it can prevent dirt with high reliability. Moreover, the replacement frequency of the transparent plate 32 can be drastically reduced by the cleaning device 33.

The figure explaining the structure of 1st Embodiment The figure explaining a mode that the image of the ink droplet 2 is imaged The figure explaining the non-ejection detection method The figure explaining the measuring method of the landing position accuracy of a droplet The figure explaining the structure of 2nd Embodiment The figure explaining operation | movement of each part of 2nd Embodiment Diagram explaining the discharge signal in detail The figure showing the test | inspection pattern by the scattered light in 2nd Embodiment A diagram showing a pattern ejected at a frequency of 50% of continuous ejection A diagram showing a pattern ejected at a frequency of 25% of continuous ejection The figure explaining the measuring method of density uniformity Diagram showing horizontal line pattern The figure explaining the measuring method of the position uniformity of a nozzle arrangement direction Diagram showing vertical line pattern The figure explaining the measuring method of the position uniformity in a head scanning direction The figure explaining the structure of 3rd Embodiment The figure explaining the structure of 4th Embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Test head 2 Droplet 5 Carriage 6 Stage 10 Illumination device 11 Illumination light 12 Imaging lens 13 Imaging element 14 TV camera 15 Control device 30 Antifouling device by airflow 31 Transparent sheet 32 Transparent plate 33 Cleaning device

Claims (3)

  A droplet discharge head measuring device that forms an image by discharging droplets by heat or other methods, projecting illumination light from a direction intersecting the flight direction of the droplets discharged from the head to be inspected, An image of scattered light of illumination light from a droplet is formed on an image sensor from a position where the illumination light is not incident, and the characteristics of the head to be inspected are measured from the image of scattered light from the droplet. Measuring device for droplet discharge head.   2. The image pickup device according to claim 1, wherein a storage-type device that outputs a signal corresponding to an integrated light amount of light incident at a predetermined time is used as an image pickup device, and droplets are ejected from a plurality of nozzles during the storage time of the image pickup device. An apparatus for measuring a droplet discharge head, wherein:   3. A droplet discharge head measuring apparatus according to claim 1, wherein the droplet discharge head is discharged while moving the head to be inspected.

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