JP2007021745A - Method for inspecting ink jet head, aging device and recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method for inspecting an ink jet head ejecting ink from a plurality of nozzles in which recording quality can be enhanced by preventing nonejection and improving impact accuracy. <P>SOLUTION: In the method for inspecting an ink jet head, aging for driving the ink jet head 7 is performed about 100 million to 1 billion times and then print inspection of the ink jet head 7 is performed. More specifically, the method for inspecting an ink jet head comprises a step for performing aging of the ink jet head 7 about 100 million to 1 billion times, and a step for performing print inspection of the ink jet head 7 for a recording medium. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inkjet head inspection method for discharging liquid ink from a plurality of nozzles. The present invention also relates to an aging apparatus and a recording apparatus used for this inspection method.

  2. Description of the Related Art Conventionally, an inkjet head that ejects ink by driving an actuator and a relative movement unit that relatively moves the inkjet head and the recording paper are provided. The relative movement unit allows the inkjet head to be relative to the recording paper. 2. Description of the Related Art There is known a recording apparatus configured to perform recording by ejecting ink onto a recording sheet from a nozzle provided in an inkjet head while moving.

  In this ink jet head print inspection method, it has been common to perform inspection by driving the ink jet several times to tens of millions of times or less.

As such an ink jet head inspection method, for example, a method of performing aging for 5 million ink ejections in order to make the impedance of the electrode surface of the ink jet head constant has been proposed (see, for example, Patent Document 1). .
JP-A-8-169119

  By the way, in such an ink jet head, after the print inspection, dust that has hidden inside the head may flow into the supply port in the flow path plate and the nozzle hole in the nozzle plate, thereby blocking the nozzle hole. In such a case, there is a possibility of a non-ejection state where ink is not ejected. Even when the hole is not completely blocked, the landing accuracy may be deteriorated, for example, when a part of the hole is blocked or when the water-repellent film around the nozzle is not uniform. It is important to detect in advance before shipping the head whether or not such non-ejection and landing accuracy have deteriorated.

  The present invention has been made in view of such circumstances. In an inkjet head that ejects ink from a plurality of nozzles, the occurrence of non-ejection is prevented and the landing accuracy is improved, thereby improving the recording quality. An object of the present invention is to obtain an ink jet head inspection method capable of achieving the above. It is another object of the present invention to obtain an aging apparatus and a recording apparatus used for this inspection method.

  The inventors focused on the fact that the printing state changes as the number of ejections is repeated in the ink ejection characteristics, and as a result of repeated experiments, the number of ejections, that is, aging, non-ejection of printing, landing position accuracy, A predetermined result was found regarding the relationship.

  In order to achieve the object, in the ink jet head inspection method of the present invention, the aging for driving the ink jet head is driven approximately 100 million to 1 billion times, and then the print inspection of the ink jet head is performed. That is, in the ink jet head inspection method of the present invention, an aging process for performing the ink jet head driving approximately 100 million to 1 billion times, a print inspection process for performing a print inspection on the recording medium of the ink jet head after the aging process, and Is included.

  In the ink jet head inspection method of the present invention, the dust hidden inside the head is removed from the pressure chamber, the flow passage plate by the aging process of performing the aging to drive the ink jet head approximately 100 million to 1 billion times, Pour into the nozzle holes in the silo and nozzle plate, and make the water-repellent film around the nozzles uniform by wetting the ink, creating a stable printing state, non-ejection of the head, landing position accuracy Thus, the recording quality of the recording apparatus can be improved.

  The present invention is characterized in that, for example, in an inspection process at the time of shipment preparation after manufacture, aging is performed 100 million to 1 billion times using a color material-less ink, and then a print inspection is performed. In aging, the used ink is reused and circulated. This was realized by using an aging device equipped with ink recovery means, filtering means, deaeration means and the like.

  An inkjet head inspection method according to claim 1 of the present invention is an inkjet head inspection method in which ink is ejected from a plurality of nozzles. After the aging process, an aging process is performed in which the inkjet head is driven approximately 100 million to 1 billion times. And a print inspection process for performing a print inspection on the recording medium of the inkjet head. With this configuration, by performing the print inspection after 1 billion times of aging, stable printing can be realized, and as a result, the occurrence of new non-ejection can be prevented and the landing accuracy can be improved.

  An ink jet head inspection method according to a second aspect of the present invention is the ink jet head inspection method according to the first aspect, wherein the aging step performs aging with a colorless ink. With this configuration, aging can be performed inexpensively and efficiently.

  The ink jet head inspection method according to claim 3 of the present invention is the ink jet head inspection method according to claim 1 or 2, wherein the aging step performs aging using an aging device that circulates and reuses ink. With this configuration, the ink is circulated and reused, so that an effect of cost reduction can be obtained.

  An ink jet head inspection method according to a fourth aspect of the present invention is the ink jet head inspection method according to the third aspect, wherein the aging device includes an ink supply means for supplying ink to the ink jet head and an ink recovery means for recovering the discharged ink. Filter means for removing impurities from the collected ink, deaeration means for degassing the ink from which impurities have been removed, and control means for controlling the ink supply means, ink recovery means, filter means, and deaeration means Have. With this configuration, the used ink is collected, and the ink can be reused by performing a cleaning process such as a filter and deaeration, so that the amount of ink used can be greatly reduced.

  The ink jet head inspection method according to claim 5 of the present invention is the ink jet head inspection method according to claim 4, wherein the dissolved oxygen amount of the ink after the deaeration means is less than or equal to the dissolved oxygen amount of the ink before ejection. It is. With this configuration, if the amount of oxygen in the ink is large, bubbles are likely to be generated in the head, causing non-ejection or deterioration in landing accuracy, but an action to prevent this can be obtained.

  The inkjet head inspection method according to a sixth aspect of the present invention is the inkjet head inspection method according to any one of the first to fifth aspects, wherein the print inspection step is performed every time the aging step is completed. With this configuration, if there is a head that is unlikely to eliminate non-ejection, the head can be dropped as NG at that time.

  An ink jet head inspection method according to a seventh aspect of the present invention is the ink jet head inspection method according to any one of the first to fifth aspects, wherein the print inspection step is performed after the aging step is performed a predetermined number of times. With this configuration, the result of non-ejection and landing position accuracy can be known.For example, if there is a head that has non-ejection after a predetermined number of times and is not expected to lose non-ejection after that number of times, at that time The head can be dropped as NG.

  The inkjet head inspection method according to claim 8 of the present invention is the inkjet head inspection method according to any one of claims 1 to 7, wherein the print inspection step uses an average value of positional deviations of adjacent dots as an ideal pitch, Print inspection is performed using the standard deviation of the positional deviation of each dot from the ideal pitch as the landing position accuracy. With this configuration, there is an effect that there is no deviation and accurate landing position accuracy is obtained.

  The ink jet head inspection method according to claim 9 of the present invention is the ink jet head inspection method according to any one of claims 1 to 8, wherein the print inspection step determines one cycle time and voltage of the drive waveform of the ink jet head. Including a condition setting step. With this configuration, there is an action that can be adjusted when there is a deviation from the optimum condition.

  An ink jet head inspection method according to a tenth aspect of the present invention is the ink jet head inspection method according to the ninth aspect, wherein the print inspection step determines one cycle time of the drive waveform based on the print test pattern. With this configuration, there is an effect that the set time is accurate.

  The ink jet head inspection method according to claim 11 of the present invention is the ink jet head inspection method according to any one of claims 1 to 10, wherein the print inspection step performs a print inspection with a print test pattern having a plurality of print frequencies. . With this configuration, printing at various frequencies is possible, and the frequency dependency of non-ejection and landing position accuracy can be inspected in detail.

  An ink jet head inspection method according to a twelfth aspect of the present invention is the ink jet head inspection method according to any one of the first to eleventh aspects, wherein the print inspection step includes a plurality of ink filling, recovery purge, and printing. Do it once. With this configuration, it is possible to obtain an effect of discharging bubbles from the head by once draining ink and refilling with ink.

  An ink jet head inspection method according to a thirteenth aspect of the present invention is the ink jet head inspection method according to any one of the first to twelfth aspects, wherein the print inspection step performs a print inspection with a plurality of ink jet heads. With this configuration, it is possible to reduce the number of print inspection steps by evaluating a plurality of heads at a time.

  An ink jet head inspection method according to a fourteenth aspect of the present invention is the ink jet head inspection method according to any one of the first to thirteenth aspects, wherein the print inspection step performs a print inspection on a plurality of recording media. With this configuration, there is an effect that more appropriate print inspection can be performed.

  The ink jet head inspection method according to claim 15 of the present invention is the ink jet head inspection method according to any one of claims 1 to 14, wherein the print inspection step includes relative movement means for relatively moving the ink jet head and the recording medium. A printing inspection is performed using a recording apparatus that performs recording by discharging ink from each nozzle of the inkjet head to a recording medium. With this configuration, there is an effect that an accurate and appropriate print inspection can be performed based on the configuration of the actual machine.

  In the aging device according to the sixteenth aspect of the present invention, the ink supply means for supplying ink to the inkjet head, the ink recovery means for recovering the ejected ink, the filter means for removing impurities from the recovered ink, and the impurities are removed. The aging according to any one of claims 1 to 15, further comprising: a deaeration unit that deaerates the ink; and an ink supply unit, an ink collection unit, a filter unit, and a control unit that controls the deaeration unit. Do. With this configuration, the ink is circulated and reused, so that an effect of cost reduction can be obtained.

  A recording apparatus according to a seventeenth aspect of the present invention includes a relative movement unit that relatively moves the inkjet head and the recording medium, and discharges ink from each nozzle of the inkjet head to the recording medium. The printing inspection described in any one of the items is performed. With this configuration, there is an effect that an accurate and appropriate print inspection can be performed based on the configuration of the actual machine.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a perspective view showing an outline of a line type ink jet recording apparatus 1 according to an embodiment of the present invention. The ink jet recording apparatus 1 includes a head block unit 2 for ejecting ink droplets onto a recording paper 6, an ink tank unit 3 for storing ink, a control block unit 4 for controlling the head block unit 2, and a head. A recovery system mechanism unit 5 that performs a recovery operation on the block unit 2 and a transport device (not shown) that transports a recording sheet 6 as a recording medium are provided.

  The head block unit 2 includes a cyan head unit 2a for ejecting cyan ink droplets onto the recording paper 6; a magenta head unit 2b for ejecting magenta ink droplets onto the recording paper 6; A yellow head portion 2 c for discharging yellow ink droplets onto the recording paper 6 and a black head portion 2 d for discharging black ink droplets onto the recording paper 6 are provided. These head portions 2a, 2b, 2c, and 2d are arranged side by side in the conveyance direction of the recording paper 6, that is, the main scanning direction X. The head block unit 2 is provided so as to be movable in the sub-scanning direction Y perpendicular to the main scanning direction X.

  FIG. 2 is a perspective view showing a configuration of a head holding plate provided with an inkjet head. As shown in FIG. 2, the cyan head section 2a holds a plurality of inkjet heads 7 arranged in the sub-scanning direction Y so as to cover the entire print area of the recording paper 6 in the sub-scanning direction Y. And a head holding plate 8. In FIG. 2, the cyan head unit 2 a includes, for example, nine inkjet heads 7. The number of heads varies depending on the print width.

  FIG. 3 is an explanatory diagram showing the configuration of the arrangement of the ink jet heads in the recording paper conveyance direction. As shown in FIG. 3, each inkjet head 7 is disposed so as to be inclined at the same angle with respect to the conveyance direction of the recording paper 6. In FIG. 3, each inkjet head 7 is disposed so as to be inclined, for example, 20 ° with respect to the conveyance direction of the recording paper 6. This angle varies depending on the arrangement of the nozzles 9 and the printing resolution.

  FIG. 4 is a cross-sectional view in the lateral direction showing the configuration of the inkjet head. FIG. 5 is a longitudinal sectional view showing the configuration of the inkjet head. FIG. 6 is a front view showing the configuration of the inkjet head. In the figure, an ink jet head 7 includes a head body in which a plurality of pressure chamber recesses 10 having a supply port 10a for supplying ink and a discharge port 10b for discharging ink are formed. The total length of each pressure chamber recess 10 opening is set to about 1120 μm and the width is set to about 115 μm. Note that both ends of the opening of each pressure chamber recess 10 have a substantially semicircular shape.

  The side wall portion of each pressure chamber recess 10 of the head body is constituted by a pressure chamber component 12 made of Ni having a thickness of about 140 μm, and the bottom wall portion of each pressure chamber recess 10 is bonded to the lower surface of this pressure chamber component 12. The ink flow path component 14 is formed by fixing and laminating ten stainless steel thin plates. In the ink flow path component 14, a plurality of orifices 17 respectively connected to the supply ports 10 a of the pressure chamber recesses 10, one supply ink flow path 16 connected to each orifice 17, and a discharge A plurality of ejection ink flow paths 13 respectively connected to the outlet 10b are formed.

  Each orifice 17 is formed in the second stainless steel plate from the top in the ink flow path component 14, and its hole diameter is set to about 40 μm. Further, the supply ink flow path 16 is connected to the ink tank 3, and ink is supplied from the ink tank 3 into the supply ink flow path 16.

  A nozzle plate 15 made of stainless steel on which a plurality of nozzles 9 for ejecting ink droplets toward the recording paper 6 is formed is bonded and fixed to the lower surface of the ink flow path component 14. The lower surface of the nozzle plate 15 is covered with a water repellent film 15a. The water repellent film 15a can be formed by a known method.

  The nozzles 9 are arranged on the nozzle plate 15 so that the arrangement density is, for example, 110 dpi.

  Piezoelectric actuators 21 are provided above the pressure chamber recesses 10 of the head body. Each piezoelectric actuator 21 is bonded and fixed to the upper surface of the head body, closes each pressure chamber recess 10 of the head body, and forms a pressure chamber 11 together with the pressure chamber recess 10. 24, a Cr diaphragm 25, an electrodeposition resin 26, and a Ni seed layer 27. The intermediate layer 24 made of Cu to the seed layer 27 made of Ni are formed of one common to all the piezoelectric actuators 21 and also serve as a common electrode common to all the piezoelectric elements 23 described later.

  Each piezoelectric actuator 21 is provided in a portion corresponding to the pressure chamber 11 on the side surface (upper surface) opposite to the pressure chamber 11 of the diaphragm 25 (a portion facing the opening of the pressure chamber recess 10) and zirconate titanate. The piezoelectric element 23 made of lead (PZT) and the piezoelectric element 23 are bonded to the side surface (upper surface) opposite to the vibration plate 25, and a voltage (drive voltage) is applied to each piezoelectric element 23 together with the vibration plate 25. And an individual electrode 22 made of Ir-Ti.

  The diaphragm 25, each piezoelectric element 23, each individual electrode 22, each intermediate layer 24, the electrodeposition resin 26, and the seed layer 27 are all formed of a thin film, and the thickness of the diaphragm 25 is about 2 μm. The thickness of the piezoelectric element 23 is about 4 μm, the thickness of each individual electrode 22 is about 0.1 μm, the thickness of each intermediate layer 24 is about 3 μm, the thickness of the electrodeposition resin 26 is about 2 μm, and the thickness of the seed layer 27 is about Each is set to 0.5 μm.

  Each piezoelectric actuator 21 applies a driving voltage to each piezoelectric element 23 via its vibration plate 25 and each individual electrode 22, so that a portion corresponding to the pressure chamber 11 of the vibration plate 25 (pressure chamber recess 10). The ink in the pressure chamber 11 is ejected from the ejection port 10b or the nozzle 9 by deforming the opening portion). That is, when a pulsed voltage is applied between the diaphragm 25 and the individual electrode 22, the piezoelectric element 23 contracts in the width direction perpendicular to the thickness direction due to the piezoelectric effect due to the rise of the pulse voltage, whereas the diaphragm 25, since the individual electrode 22 and the intermediate layer 24 do not contract, a portion corresponding to the pressure chamber 11 of the diaphragm 25 is bent and deformed in a convex shape toward the pressure chamber 11 due to a so-called bimetal effect. This bending deformation increases the pressure in the pressure chamber 11, and the ink in the pressure chamber 11 is pushed out from the nozzle 9 through the discharge port 10 b and the discharge ink flow path 13 by this pressure. Then, the piezoelectric element 23 expands due to the fall of the pulse voltage, and the portion corresponding to the pressure chamber 11 of the diaphragm 25 returns to the original state. At this time, the ink pushed out from the nozzle 9 is the ink flow path 13. The ink is torn off from the ink and discharged onto the recording paper 6 as ink droplets (for example, 15 pl) and adheres to the surface of the recording paper 6 in the form of dots. At this time, the minimum dot diameter is set to be 80 μm or less.

  In addition, when the vibration plate 25 is bent and deformed to return to the original state, the pressure chamber 11 is filled with ink from the ink cartridge 3 through the supply ink flow path 16 and the supply port 10a. Is done. The pulse voltage applied to each piezoelectric element 23 falls from the first voltage to the second voltage lower than the first voltage, even if it is not a push-pull type as described above. It may be of a pulling type that rises to the first voltage later.

  FIG. 7 is an explanatory diagram showing a comparison of components of normal ink and color material-less ink. As shown in FIG. 7, the ink used for printing is composed of a coloring material, water, a moisturizing agent, a penetrating agent, an antifoaming agent, and an antifungal agent. The physical properties of the ink are, for example, a viscosity of about 3.5 cp, a surface tension of about 34.0 mN / m, and a pH of about 8.0. Color material-less ink used for aging is a composition that excludes the color material from the ink, and further adjusts the ratio of moisturizer, penetrant, and antifoaming agent because the physical property value changes greatly due to the effect of removing the color material And the same physical properties as the ink used for printing.

  FIG. 8 is a schematic diagram showing the configuration of the aging apparatus. In FIG. 8, an aging device 1001 includes an inkjet head 7, a control board 31, an amplifier 32, a personal computer (hereinafter simply referred to as a personal computer) 33 constituting control means, color material-less ink, an ink main tank 41, and the like. , An ink sub-tank 42, an ink recovery container 51, a purge cap 52, a tubing pump 61, a filter 62, a deaeration device 63, an ink mist recovery device 70, and a dry air device 71.

  The ink main tank 41 and the ink sub tank 42 constitute ink supply means for supplying ink to the inkjet head 7. The ink collection container 51 constitutes an ink collection unit that collects the discharged ink. The filter 62 constitutes filter means for removing impurities from the collected ink. The deaeration device 63 constitutes a deaeration unit that degass the ink from which impurities have been removed.

  It is said that the ink can be filled into the ink sub tank 42 by its own weight from the ink main tank 41. Once the ink sub tank 42 is filled with ink, the ink flow path is closed by the cock provided in the middle. Thereafter, when ink is discharged and the ink in the ink sub tank 42 is reduced by a predetermined amount, the cock is opened and ink is newly filled from the ink main tank 41. By repeating this operation, the ink sub tank 42 is always filled with ink. Further, instead of this manual operation, a liquid level sensor may be installed in the ink sub tank 42 so that the ink is automatically supplied from the ink main tank 41 when the ink is reduced.

  Further, the ink collection container 51 and the purge cap 52 are configured to be able to move alternately to the position of the inkjet head 7.

  The tubing pump 61 has a role of guiding the color material-less ink collected in the ink collection container 51 to the filter 62, the deaerator 63, and further to the main tank 41.

  The deaeration device 63 is a device for reducing dissolved oxygen in the ink. In the present invention, the amount of dissolved oxygen in the ink after ejection and deaeration is the same as or less than the amount of dissolved oxygen in the ink before ejection. It is characterized by being. Specifically, the dissolved oxygen amount of ink is 1 ppm or less as a set value. If the amount of oxygen in the ink is large, bubbles are likely to be generated in the head, which causes non-ejection or deterioration of landing accuracy.

  The ink mist collecting device 70 is a device for sucking and collecting ink mist because the ink mist generated when continuously ejecting a large amount of ink may deteriorate the surrounding environment of the device.

  Next, an experimental method will be described.

  The apparatus used for the experiment includes an inkjet head 7, a control board 31, an amplifier 32, a personal computer 33, ink, an ink main tank 41, an ink sub tank 42, an ink collection container 51, a purge cap 52, A tube pump 61, a vacuum pump (not shown), a filter 62, an ink mist collection device 70, and a dry air device 71 are provided.

  The experimental procedure will be described. In advance, the piezoelectric element 23 of the ink jet head 7 is filled with dry air produced by the dry air device 71 so that the short breakage does not occur, and the dew point in the head is set to −40 ° C. . Next, the purge cap 52 is brought into close contact with the ink jet head 7 connected with the main tank 41 and the sub tank 42 filled with ink, the tubing pump 61 is operated to fill the ink, and the residual ink adhered to the nozzle surface of the ink jet head 7. Wipe off.

  The control board 31 and the amplifier 32 are operated using the personal computer 33, and 15 pl and 16 kHz discharge are started. At this time, since the ink mist flies, the ink mist is collected by the ink mist collecting device 70 that is close to the nozzle surface. The ejected ink is received by the ink recovery container 51, and is led to a waste liquid can by a vacuum pump and stored.

  This work will be continued up to 20 billion times. Then, the head is removed and printing is performed by the printing device every 0.25 million joints. For the printed sample, the non-ejection occurrence rate, which is the ratio of the number of non-ejection pins to the total number of ejection pins of the head, is obtained, and the X-direction landing accuracy and Y-direction are determined using an image evaluation apparatus IAS-1000 manufactured by QEA. The landing accuracy was measured.

  Here, a method for measuring the landing accuracy will be described. First, the center of gravity of the landed dot is measured using an image evaluation device. Assuming that the X coordinate or Y coordinate is A1, A2, A3,... For each nozzle, the difference between the dot positions of adjacent nozzles is L1 = A2-A1, L2 = A3-A2, L3 = A4. -A3,... If the average value of L1, L2, L3,... Is X, the ideal dot positions of the nozzles are B1 = A1, B2 = A1 + X, B3 = A1 + 2X,. In the present invention, the landing position deviation of each nozzle is P1 = B1-A1, P2 = B2-A2, P3 = B3-A3,..., And the total landing position deviation is P1, P2, P3,. Was obtained as the n-1 method standard deviation σ.

  As described above, in the print inspection process, the average value of the positional deviations of adjacent dots is set as the ideal pitch, and the print inspection is performed using the standard deviation of the positional deviation of each dot from the ideal pitch as the landing position accuracy. With this configuration, there is no bias and accurate landing position accuracy can be obtained.

  After the landing measurement is completed, the head is mounted again on the experimental apparatus and restarted from the ink filling.

  Next, regarding the experimental conditions, the recording resolution of the printing apparatus used in the experiment is 600 dpi, the ink droplet amount is 15 pl, the ejection frequency is 16 kHz, and the distance between the nozzle and the recording paper during printing. Is 1 mm. The dew point of the head with dry air is about −40 ° C. Discharge continued up to 20 billion times. As the recording paper, a commercially available photo glossy film was used.

  Next, the actual experimental results will be described.

  FIG. 9 shows discharge test data up to 500 million times concerning the non-discharge occurrence rate. The horizontal axis represents the number of ejections (100 million times), and the vertical axis represents the non-ejection occurrence rate (%). The non-ejection occurrence rate gradually increases up to 100 million times from the initial stage of ejection, and is almost constant after 100 million times. From this data, it can be considered that the dust existing in the head is flowing out to the nozzle up to 100 million times. Therefore, in the present invention, in order to prevent the occurrence of a new non-ejection, the aging ejection number is set to 100 million or more.

  FIG. 10 shows discharge test data up to 3 billion times regarding landing position deviation in the main scanning (X) direction. The horizontal axis indicates the number of ejections (100 million times), and the vertical axis indicates the X-direction landing deviation σ. From the initial discharge, the dispersion of X landing has improved rapidly up to 100 million times, and gradually improved from 100 million to 1 billion times. Moreover, it is almost constant after 1 billion times.

  FIG. 11 shows discharge test data up to 3 billion times regarding the landing position deviation in the sub-scanning (Y) direction. The horizontal axis indicates the number of ejections (100 million times), and the vertical axis indicates the Y-direction landing deviation σ. Similar to the X landing deviation, the Y landing deviation improves sharply from 100 million times from the initial stage of ejection, gradually improves from 100 million to 1 billion times, and becomes almost constant after 1 billion times.

  From these data, if the print inspection is performed after aging discharge 1 billion times, stable printing can be realized. As a result, the occurrence of new non-discharge is prevented, the landing position accuracy is improved, and the recording quality is improved. Can be achieved.

  In consideration of the man-hour and life of the head, it is preferable that the number of ejections at the time of print inspection is as small as possible, and the landing position accuracy is gradually improved from 100 million times to 1 billion times. Even if it is less than 100 million times, that is, several hundred million times, roughly the same effect can be obtained.

  As described above, as a result of repeated experiments, the inventors have found a predetermined result regarding the relationship between the number of ejections, that is, aging, non-ejection of printing, and landing position accuracy, and based on this, an ideal inspection method is found. Was invented. That is, it is a method of performing a print inspection of the inkjet head 7 after driving the inkjet head 7 for aging approximately 100 million to 1 billion times. That is, in the inspection method for the inkjet head 7 of the present invention, an aging process for driving the inkjet head 7 approximately 100 million to 1 billion times, and a print inspection for the recording medium of the inkjet head 7 is performed after the aging process. A printing inspection process.

  Thus, by performing the print inspection after 1 billion times of aging, stable printing can be realized, and as a result, the occurrence of new non-ejection can be prevented and the landing accuracy can be improved. On the other hand, considering the man-hour and life of the head, it is preferable that the number of times of aging is as small as possible, and the landing position accuracy is gradually improved from 100 million times to 1 billion times. In other words, the effect can be obtained even if it is several hundred million times, and this range is considered to be the optimum range.

  Further, in this ink jet head inspection method, the aging step performs aging with the color material-less ink. It has been found that a large amount of ink is required to eject 1 billion times, but a color material is not necessarily required because printing is not performed. The color material-less ink is characterized in that it does not use a color material for the ink composition and has the same physical properties as the ink. Thereby, aging can be performed inexpensively and efficiently.

  Further, in this ink jet head inspection method, the aging step performs aging using an aging device 101 that circulates and reuses ink. With this configuration, the ink is circulated and reused, so that an effect of cost reduction can be obtained.

  Furthermore, in this ink jet head inspection method, the print inspection process is performed after the aging process is performed a predetermined number of times. As a result, in this inspection method, the result of non-ejection and landing position accuracy can be known, for example, there was a head where non-ejection occurred at a predetermined number of times, and there was no possibility that non-ejection would disappear after that number of times. Then, at that time, the head can be dropped as NG.

  The print inspection process includes a condition setting process for determining one cycle time and voltage of the drive waveform of the inkjet head 7. This condition setting process determines one cycle time of the drive waveform based on the print test pattern. With this configuration, it is possible to accurately determine one cycle time and voltage. The optimum one cycle time can be determined simply by changing several types of one cycle time of the drive waveform and printing. When deviating from the optimum conditions, white streaks are generated in printing, so that it can be easily determined with the naked eye.

  Furthermore, in this ink jet head inspection method, the print inspection step performs a print inspection with a print test pattern having a plurality of print frequencies. If there is only one series, only the frequency equivalent to the common divisor of the maximum frequency can be printed, but by having multiple series, it is possible to print more various frequencies, and the frequency dependence of non-ejection and landing position accuracy is detailed. Can be inspected.

  Furthermore, in the print inspection process, ink filling to the ink jet head 7, recovery purge, and printing are performed a plurality of times. If air bubbles get caught in the gap in the head, non-ejection often does not recover even if the number of recovery purges is repeated in a single filling. Bubbles can be discharged from the head by once draining ink and refilling with ink.

  In this ink jet head inspection method, the print inspection step performs a print inspection on a plurality of recording media. For example, inkjet paper, which is one of the recording media, includes plain paper, matte paper, glossy paper, and the like. By properly using paper depending on the item to be inspected, inspection suitable for each inspection item can be performed. For example, if it is landing position accuracy, glossy paper that can obtain dots that are close to a perfect circle can determine the accurate center of gravity, and if you want to judge non-ejection, cheaper matte paper is sufficient. Can be fulfilled. In addition, it is possible to use such as inspecting the blurring characteristic or density unique to plain paper.

  As described above, in the ink jet head inspection method of the present embodiment, the dust hidden inside the head is removed from the pressure chamber, the flow path by the aging process in which the ink jet head 7 is driven approximately 100 million to 1 billion times. Pour into the supply port in the plate, the silo, and the nozzle hole in the nozzle plate, and make the water-repellent film around the nozzle uniform by wetting the ink, creating a stable printing state, and the head This makes it possible to accurately determine the non-ejection and landing position accuracy, thereby improving the recording quality of the recording apparatus.

  In addition, the used ink is collected and then subjected to a cleaning process such as filtering and deaeration, so that it can be reused and the amount of ink can be saved. Further, the ink may be configured not to contain a color material. By using colorless ink and reusing and circulating the ink, an inexpensive and efficient process can be achieved.

  The inkjet head inspection method according to the present invention can create a stable printing state by aging ranging from 100 million to 1 billion, and can accurately determine an inkjet head with non-ejection and landing position accuracy in the inspection process. Become. Therefore, a stable and reliable printing operation can be ensured after the head is shipped until the end of its life. This aging is more effective as the number of ejections is repeated from the beginning of ejection. However, when man-hours and life are taken into consideration, an effect of improving landing accuracy can be expected even with a smaller number of ejections. Therefore, the present invention can be applied not only to industrial use but also to the manufacturing process of consumer inkjet printers.

  Furthermore, by using the color material-less ink and reusing the used ink, it is possible to perform aging at low cost and with high efficiency. This ink recycling system can also be applied to industrial printing machines, and if the ink used in large quantities by purging the inkjet head is returned to the ink tank using the recycling system of the present invention, the amount of ink used Can be greatly reduced.

1 is a perspective view illustrating an outline of a line-type ink jet recording apparatus according to an embodiment of the present invention. The perspective view which shows the structure of the head holding plate provided with the inkjet head. Explanatory drawing showing the configuration of the arrangement of the inkjet head with respect to the recording paper conveyance direction Cross-sectional view in the short direction showing the configuration of the inkjet head Longitudinal sectional view showing the configuration of the inkjet head Front view showing configuration of inkjet head Explanatory drawing showing comparison of components of normal ink and color material-less ink Schematic diagram showing the configuration of the aging device Graph showing transition of non-ejection occurrence rate in ejection test Graph showing the transition of X landing variation σ in the discharge test Graph showing the transition of Y landing variation σ in the discharge test

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording device 2 Head block part 2a Cyan head part 2b Magenta head part 2c Yellow head part 2d Black head part 3 Ink tank part 3a Cyan ink tank part 3b Magenta ink tank part 3c Yellow ink tank part 3d Black ink tank section 4 Control block section 5 Recovery system mechanism section 6 Recording paper 7 Inkjet head 8 Head holding plate 9 Nozzle 10 Pressure chamber recess 10a Supply port 10b Ejection port 11 Pressure chamber 12 Pressure chamber component 13 Ejection ink channel 14 Ink channel parts 15 Nozzle plate 15a Water repellent film 16 Supply ink channel 17 Orifice 21 Piezoelectric actuator 22 Individual electrode 23 Piezoelectric element 24 Intermediate layer 25 Vibration plate 26 Electrodeposition resin 27 Seed layer 31 Control substrate 32 Amplifier 33 Personal Computer (control means)
41 Ink main tank (ink supply means)
42 Ink sub tank (ink supply means)
51 Ink collection container (ink collection means)
52 Purge cap 61 Tubing pump 62 Filter (filter means)
63 Deaeration device (deaeration means)
70 Ink Mist Collection Device 71 Dry Air Device 101 Aging Device

Claims (17)

In the inspection method of an inkjet head that discharges ink from a plurality of nozzles,
An aging step of performing aging to drive the inkjet head approximately 100 million to 1 billion times;
An inkjet head inspection method comprising: a print inspection step of performing a print inspection on the recording medium of the inkjet head after the aging step. The inkjet head inspection method according to claim 1, wherein the aging step performs the aging with a color material-less ink. The inkjet head inspection method according to claim 1, wherein the aging is performed using an aging device that circulates and reuses ink. The aging device is
Ink supply means for supplying ink to the inkjet head;
An ink collecting means for collecting the discharged ink;
Filter means for removing impurities from the collected ink;
A degassing means for degassing the ink from which impurities have been removed;
The inkjet head inspection method according to claim 3, further comprising a control unit that controls the ink supply unit, the ink recovery unit, the filter unit, and the deaeration unit. The inkjet head inspection method according to claim 4, wherein the dissolved oxygen amount of the ink after the deaeration unit is performed is equal to or less than the dissolved oxygen amount of the ink before ejection. 6. The inkjet head inspection method according to claim 1, wherein the print inspection step is performed every time the aging step is completed. The inkjet head inspection method according to claim 1, wherein the print inspection step is performed after the aging step is performed a predetermined number of times. 2. The print inspection step performs the print inspection with an average value of positional deviations of adjacent dots as an ideal pitch and a standard deviation of positional deviation of each dot from the ideal pitch as a landing position accuracy. 8. The inkjet head inspection method according to any one of 7 above. The ink jet head inspection method according to claim 1, wherein the print inspection step includes a condition setting step for determining one cycle time and voltage of the drive waveform of the ink jet head. 10. The inkjet head inspection method according to claim 9, wherein the print inspection step determines one cycle time of the drive waveform based on a print test pattern. 11. The inkjet head inspection method according to claim 1, wherein the print inspection step performs a print inspection using a print test pattern having a plurality of print frequencies. The ink jet head inspection method according to claim 1, wherein the print inspection step performs ink filling, recovery purge, and printing a plurality of times on the ink jet head. The ink jet head inspection method according to claim 1, wherein the print inspection step performs a print inspection with a plurality of the ink jet heads. The inkjet head inspection method according to claim 1, wherein the print inspection step performs a print inspection on a plurality of recording media. The print inspection process includes
Print inspection is performed using a recording apparatus that includes a relative movement unit that relatively moves the inkjet head and the recording medium, and performs recording by discharging ink from the nozzles of the inkjet head to the recording medium. The inkjet head inspection method according to any one of claims 1 to 14. Ink supply means for supplying ink to the inkjet head;
An ink collecting means for collecting the discharged ink;
Filter means for removing impurities from the collected ink;
A degassing means for degassing the ink from which impurities have been removed;
16. An aging apparatus comprising: the ink supply unit, the ink recovery unit, the filter unit, and a control unit that controls the deaeration unit, wherein the aging is performed according to any one of claims 1 to 15. . The print inspection according to claim 1, further comprising a relative movement unit that relatively moves the inkjet head and the recording medium, and ejecting ink from the nozzles of the inkjet head to the recording medium. A recording apparatus.

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