JP5369757B2 - Ink droplet detection apparatus, ink jet printer, and ink droplet detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink drop detection device that determines ink drop jetting performance by speedily and appropriately detecting an ink drop, and also to provide an ink jet printer, ink drop detection method, ink drop detection program, and recording medium. <P>SOLUTION: Each time a nozzle to be inspected for an ink jet head 2 is changed, an ink jet detection mechanism unit 3 of the ink jet printer 1 outputs a DC output voltage which alternates polarities, to a charging electrode 12 from a two-pole output DC power source 11. The mechanism unit 3 also applies charges of the reverse polarity of the DC output voltage to an ink drop Ti jetted from the nozzle by the charging electrode 12. The mechanism unit 3 accumulates charges in a capacitor 14, the charges having the reverse polarity of the charges of ink drop Ti, which is generated in a detection electrode 13 near which the charged ink drop Ti is passed. Based on the accumulated charges, the mechanism unit 3 determines whether jetting of ink drop from the nozzle to be inspected is appropriate. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to an ink droplet detection device, an ink jet printer, and an ink droplet detection method, and more specifically, an ink droplet detection device and an ink droplet detection method for determining ink droplet ejection performance of a nozzle by quickly and appropriately detecting ink droplets. It relates to an inkjet printer and an ink droplet detecting how to mount the device.

  Inkjet printers do not require processes such as development and fixing, can form images without contact, are easy to colorize, have extremely low noise during recording, are capable of high-speed printing, and are free of ink. Since it has many advantages such as the ability to use plain paper that is inexpensive and inexpensive, it is widely used in image forming apparatuses such as printers, copiers, and facsimile machines.

  Among these ink jet systems, a so-called drop-on-demand type that ejects ink droplets only when printing and recording is necessary does not require collection of ink droplets that are not necessary for recording, and is currently mainstream.

  The ink jet printer generally has an ink head having a plurality of nozzles, an ink liquid chamber for each color in which each nozzle of each color communicates, and an actuator disposed corresponding to each nozzle for each color, Recording is performed on paper (recording medium) by pressurizing the ink in the ink liquid chamber by the displacement or heat generation of the actuator and ejecting ink droplets (ink droplets) from the nozzles.

  However, since the ink jet printer ejects ink droplets through fine nozzles, the ink ejection performance deteriorates due to the ink droplets adhering to the tip of the nozzle and solidifying, and the image quality of the formed image may be degraded.

  Therefore, conventionally, an ink jet printer includes an ink droplet detection mechanism that detects ink droplets ejected from nozzles, and a cleaning mechanism that removes ink waste by cleaning (wiping) the ejection port portion of the nozzles, When it is determined that the nozzle needs to be cleaned based on the detection result of the ink droplet detection mechanism, the nozzle is cleaned by the cleaning mechanism.

  In order to determine whether or not the cleaning mechanism unit needs to clean the nozzle, the conventional ink jet printer uses a direct current voltage (for example, a predetermined negative charge to the ink droplet ejected from the nozzle as the ink droplet detection mechanism unit). , + 100V), a detection electrode that detects an induced voltage that is induced by the collision of an ink droplet to which the charge is applied, and an induced voltage that the detection electrode detects during a predetermined period of time. Storage means for storing as a negative electrode, and a negative charge is applied to the ink droplet ejected by the contact method so as to collide with the detection electrode from the nozzle, and the induced voltage generated at the detection electrode is detected by the storage means. Accumulation as a voltage is performed, and whether or not ink droplets are ejected by a nozzle is determined based on a detection voltage of an accumulation unit (patent) Document reference 1).

  In addition, as an ejection method for ejecting ink droplets from the nozzles in order to detect the suitability of ink droplet ejection from the nozzles, a contact method in which ink droplets are ejected toward the detection electrodes as described in Patent Document 1 above. In addition, there is a non-contact method in which an ink droplet is ejected from a nozzle so that the ink droplet passes near the detection electrode.

  However, in the above prior art, a negative charge is applied to an ink droplet ejected for ink droplet detection by a charged electrode that generates a DC voltage, and the ink droplet to which the negative charge is applied becomes a detection electrode. In this case, the induced voltage generated in the detection electrode is accumulated as a detection voltage in the accumulating means to determine whether or not the ink droplet is ejected. Therefore, only a negative charge is applied to the ink droplet, and the accumulating means Only the positive voltage is accumulated. As a result, the prior art requires a process for resetting the positive voltage accumulated in the accumulation means every time the nozzle for ink droplet detection is changed, and it takes time to shift to the ink droplet detection operation for the next nozzle. Therefore, there is a problem that the entire processing time becomes long.

  That is, in the prior art, an ink droplet is ejected from a nozzle, a negative charge is applied to the ink droplet by a charged electrode that outputs a DC voltage, and an induced voltage generated at the detection electrode by the negative charge of the ink droplet is generated. When it is stored as a detection voltage in the storage means and the detection voltage reaches a predetermined set voltage, it is determined that ink droplet ejection is appropriate. In the prior art, as shown in FIG. 6, when the time required for determining whether ink droplet ejection is appropriate (charging time) takes 0.55 ms, the detection voltage stored in the storage means is detected. 1 ms is required as a reset time (discharge time) required for discharging and resetting. Therefore, every time the ink droplet detection operation of the nozzle is performed, there is a problem that a reset time for discharging and resetting the storage means is required, and the ink droplet detection processing time, which is a non-operation time of the ink jet printer, is longer by the reset time. there were.

  In addition, in the case of the non-contact method in which the ink droplet for inspection is ejected so as to pass through the vicinity of the detection electrode, in the conventional technique, only a negative charge is applied to the ink droplet, so the ink ejected from the nozzle There is also a problem that the droplets repel each other and float in the air, the ink droplets adhere to each part inside the apparatus of the ink jet printer, and the inside of the apparatus becomes dirty.

The present invention relates to an ink droplet detecting device capable of shortening the ink droplet detection process time, and its object is to provide an ink jet printer, the ink drop detection how.

  In order to achieve the above object, the present invention outputs a DC voltage alternating in polarity at a predetermined timing from a power supply means capable of outputting a DC voltage of a predetermined voltage having a different polarity to the charging electrode, and the charging electrode causes the ink head to A charge having a polarity opposite to that of the direct current voltage is applied to an ink droplet ejected from a nozzle to be inspected among a plurality of nozzles, and the charged ink droplet is generated at a detection electrode that collides or passes nearby. Charges having a polarity opposite to that of the ink droplets are accumulated in the charge accumulating means, and the suitability of ink droplet ejection from the nozzle to be inspected is determined based on the accumulated charges.

  Further, according to the present invention, if the ink droplet ejection of the nozzle to be inspected is inappropriate, the DC voltage for the next nozzle to be inspected has the same polarity as the DC voltage for the nozzle determined to be inappropriate for the ink droplet ejection. A DC voltage may be output from the power supply means.

  Furthermore, the present invention may be characterized in that if the ink droplet ejection is inappropriate for a predetermined number or more of the nozzles of the ink head, the nozzle cleaning means cleans the nozzles.

  According to the present invention, it is possible to sequentially detect the suitability of ink droplet ejection from the nozzles for a plurality of nozzles in succession, thereby shortening the ink droplet detection processing time of the nozzles.

1 is a schematic configuration diagram of a main part of an ink jet printer to which an embodiment of the present invention is applied. The figure which shows the output voltage of a 2 pole output DC power supply part, and the detection voltage of an amplifier circuit. Explanatory drawing of an ink droplet detection process. The figure which shows the output voltage of the 2 pole output DC power supply part at the time of abnormality, and the detection voltage of an amplifier circuit. Explanatory drawing of the behavior of the ejected ink droplet. Explanatory drawing of the ink droplet detection process of the nozzle by a prior art.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, since the Example described below is a suitable Example of this invention, various technically preferable restrictions are attached | subjected, However, The range of this invention is unduly limited by the following description. However, not all the configurations described in the present embodiment are essential constituent elements of the present invention.

  1 to 5 are diagrams showing an embodiment of an ink droplet detection device, an ink jet printer, an ink droplet detection method, an ink droplet detection program, and a recording medium according to the present invention, and FIG. 1 shows an ink droplet detection according to the present invention. 1 is a schematic configuration diagram of a main part of an inkjet printer 1 to which an embodiment of an apparatus, an inkjet printer, an ink droplet detection method, an ink droplet detection program, and a recording medium are applied.

  In FIG. 1, an ink jet printer 1 includes an ink head 2 and an ink droplet detection mechanism unit 3, and feeds and conveys a sheet (recording medium) that is an object of image formation by the ink head 2, although not shown. A paper feed mechanism, a main scanning mechanism that moves the ink head 2 in a main scanning direction orthogonal to the paper conveyance direction, a controller that controls the overall operation of the inkjet printer 1, and the like are provided.

  The controller unit (determination unit, control unit) includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. In the ROM, a basic program as the inkjet printer 1 and the present invention are provided. A program such as an ink droplet detection program for executing the ink droplet detection method and necessary system data are stored. The controller unit performs basic processing as the ink jet printer 1 by controlling each unit of the ink jet printer 1 while using the RAM as a work memory based on a program in the ROM, and the ink droplets of the present invention. Execute the detection method.

  That is, the inkjet printer 1 includes ROM, EEPROM (Electrically Erasable and Programmable Read Only Memory), EPROM, flash memory, flexible disk, CD-ROM (Compact Disc Read Only Memory), CD-RW (Compact Disc Rewritable), DVD ( An ink droplet detection program that executes the ink droplet detection method of the present invention recorded on a computer-readable recording medium such as a digital video disk (SD), a secure digital (SD) card, or an MO (Magneto-Optical Disc) is read. By being installed in a ROM or the like, the ink jet printer is constructed as an ink jet printer provided with an ink droplet detection mechanism unit 3 that appropriately executes ink droplet detection processing described later at high speed. This ink droplet detection program is a computer-executable program written in a legacy programming language such as assembler, C, C ++, C #, Java (registered trademark) or an object-oriented programming language, and is stored in the recording medium. And can be distributed.

  The main scanning mechanism section extends in the main scanning direction, a guide shaft disposed in the main scanning direction, a carriage that is movably supported by the guide shaft, and moves the carriage in the main scanning direction along the guide shaft. The ink head 2 is moved in the main scanning direction when the drive motor rotates and the carriage moves along the guide shaft.

  Although not shown, the ink head 2 is equipped with a nozzle plate on which a plurality of nozzles (for example, nozzles of black, cyan, magenta, and yellow) are formed, and each nozzle has ink of a corresponding color. Supplied. The ink head 2 may have a plurality of nozzles for each color.

  The inkjet printer 1 ejects ink from the nozzles of the ink head 2 toward the paper based on the image data while moving the carriage on which the ink head 2 is mounted in the main scanning direction, thereby completing image formation for one main scanning. Then, an image is formed on the paper by repeatedly performing the process of transporting the paper in the sub-scanning direction by a sub-scanning width that forms an image for one main scanning.

  The ink jet printer 1 detects the ink droplet ejection performance of each nozzle of the ink head 2 by positioning the ink head 2 at a position facing the ink droplet detection mechanism 3 at least when the ink jet printer 1 is not driven.

  The ink droplet detection mechanism unit (ink droplet detection device) 3 is disposed in a non-image forming region in the movement range of the ink head 2 in the main scanning direction, and has a bipolar output DC power source 11, a charging electrode 12, a detection electrode 13, A capacitor C14 and an amplifier circuit 15 are provided.

  The two-pole output DC power supply unit (power supply means) 11 charges a high-voltage DC (direct current) voltage whose polarity (plus or minus) changes in a pulse shape for each nozzle to be detected with ink droplets under the control of the controller unit. 12 is output.

  The charged electrode 12 is disposed in a state facing the ink head 2 at a position where the ink head 2 stops when detecting ink droplet ejection performance, and passes through a passage region 12a through which the ink droplet Ti ejected from the ink head 2 passes. Have. According to the DC voltage supplied from the bipolar output DC power supply unit 11, the charging electrode 12 is ejected from the ink head 2 with a charge having a polarity opposite to the DC voltage, as indicated by +/− in FIG. 1. The ink droplet Ti passing through the passage region 12a is charged.

  The detection electrode 13 is disposed in the vicinity of the passage line of the ink droplet Ti ejected from the ink head 2 and passed through the charging electrode 12, and is charged to the ink droplet Ti by the ink droplet Ti passing through the vicinity. A charge of the opposite polarity to that of the charged charge is induced. A terminal on one side of the capacitor 14 is connected to the detection electrode 13, and an amplifier circuit 15 is connected to the detection electrode 13, and a terminal on the other side of the capacitor 14 is grounded.

  The capacitor (charge storage means) 14 stores the charge induced in the detection electrode 13 and outputs the stored voltage to the input of the amplifier circuit 15.

  The amplifier circuit 15 amplifies the accumulated voltage of the capacitor 14 by a predetermined multiple (for example, several tens of times) and outputs a detection voltage.

  The ink jet printer 1 converts the detection voltage output from the amplification circuit 15 into a digital detection signal by an analog / digital circuit (not shown) and inputs the digital detection signal to the controller unit. The controller unit detects the detection target based on the detection signal. Appropriateness of the ink droplet ejection of the nozzle is determined.

  The ink head 2 is equipped with a plurality of nozzles, and the controller unit determines whether or not ink droplet ejection is appropriate for each nozzle, and nozzles that are inappropriate for ink droplet ejection occur more than the preset number of cleanings. Then, a cleaning mechanism (nozzle cleaning means) (not shown) is driven to clean all nozzles.

  Next, the operation of this embodiment will be described. The inkjet printer 1 continuously inspects the nozzles by the ink droplet detection mechanism unit 3 without resetting the capacitor 14 that accumulates the charge induced in the detection electrode 13 used for the inspection of the ink droplet ejection performance for each nozzle. Do.

  That is, the ink jet printer 1 moves the ink head 2 to the position of the ink droplet detection mechanism unit 3 at a predetermined ink droplet detection timing, and performs ink droplet detection processing for each nozzle mounted on the ink head 2. Run. First, the inkjet printer 1 supplies a DC output voltage with a predetermined polarity, for example, a positive polarity DC output voltage to the charging electrode 12 as shown in FIG. . FIG. 2A shows a state where a positive DC output voltage is supplied to the charging electrode 12, n + 1 is a negative DC output voltage, n + 1 is a negative DC output voltage, and n + 2 is a positive DC output voltage. Yes.

  First, the ink jet printer 1 drives the first detection target nozzle of the ink head 2 to pass the ink droplet Ti in the vicinity of the detection electrode 13 in a state where a positive polarity DC output voltage is supplied to the charging electrode 12. The ink droplet Ti is passed through the passage region 12a of the charging electrode 12 and the vicinity of the detection electrode 13 is passed. At this time, the ink droplet Ti is charged with a charge having a polarity opposite to the polarity of the DC output voltage of the charging electrode 12. Now, since a positive DC output voltage is supplied to the charging electrode 12 from the bipolar output DC power supply unit 11, the ink droplet Ti ejected from the first nozzle to be inspected is charged with a negative charge.

  When the negatively charged ink droplet Ti passes in the vicinity of the detection electrode 13, a positive charge having a polarity opposite to that of the ink droplet Ti is induced on the detection electrode 13, and the charge induced on the detection electrode 13 is generated. The voltage is sequentially stored in the capacitor 14 and a voltage corresponding to the amount of charge stored in the capacitor 14 is input to the amplifier circuit 15. The amplification circuit 15 amplifies a voltage corresponding to the amount of charge accumulated in the capacitor 14 and outputs it as a detection voltage. This detection voltage is ejected from the ink head 2 and charged by the charging electrode 12. As shown in FIGS. 2 and 3, the controller gradually increases, and the controller unit compares the digital detection voltage obtained by digitally converting the detection voltage with a preset ink droplet ejection determination voltage. If the detected voltage exceeds the ink droplet ejection determination voltage within the determined determination time (for example, 0.55 ms), it is determined that the ink droplet ejection of the nozzle is appropriate. 2.85 V shown in FIGS. 2 and 3 indicates the DC bias voltage of the amplifier circuit 15, and when the capacitor 14 is saturated, the output voltage of the amplifier circuit 15 becomes the saturation voltage (in FIGS. 2 and 3, 3.3V).

  When the controller ends the ink drop detection process for the first nozzle, the controller outputs 1 to the bipolar output DC power supply 11 in order to detect the ink drop for the next nozzle, as shown as n + 1 in FIG. A DC output voltage having a polarity opposite to the DC output voltage (negative polarity in FIG. 2) in the ink droplet detection process of the previous nozzle is supplied to the charging electrode 12, and an ink droplet is supplied from the next nozzle to be inspected to the ink head 2. And the ink droplet detection process is performed in the same manner as described above. When a DC output voltage having the opposite polarity is applied to the charging electrode 12 and an ink droplet is ejected from the nozzle, the charge (for example, negative charge) induced in the ink droplet detection processing of the previous nozzle is applied to the detection electrode 13. As shown in FIG. 3, a negative charge charged in the previous ink drop detection process is discharged in the next ink drop detection process. The Therefore, the amplification circuit 15 that amplifies the input voltage corresponding to the charging voltage of the capacitor 14 gradually decreases from a predetermined saturation voltage (for example, 3.3 V) as shown in FIG. Is 0V, and is completely discharged.

  Then, the controller unit further performs the ink droplet detection process of the next nozzle (for example, the (n + 2) th nozzle), the DC output in the ink droplet detection process of the previous nozzle to the bipolar output DC power supply unit 11. A DC output voltage having a polarity opposite to the voltage (negative polarity in FIG. 2) is supplied to the charging electrode 12, and an ink droplet is ejected from the nozzle to be inspected to the ink head 2 to detect ink droplets in the same manner as described above. Process.

  The controller unit switches the polarity of the DC output voltage output from the two-pole output DC power source unit 11 for each nozzle to be inspected, thereby continuously detecting the ink droplets of the nozzle without discharging the capacitor 14 by reset processing. Process.

  Then, the controller unit performs the ink droplet detection process for each nozzle, and sequentially outputs DC output voltages having alternating polarities from the bipolar output DC power source unit 11 to the charging electrode 12 as shown in FIG. Thus, whether or not the ink droplet ejection from the nozzle is appropriate is determined based on the change in the detection voltage, and as shown in FIG. 4B, the discharge of the detection voltage or the charge (discharge in FIG. 4B) is appropriate. Otherwise, when an ink droplet ejection abnormality of the detection target nozzle is detected, even if the ink droplet detection timing of the next nozzle is reached, as shown in FIG. Without inverting the polarity of the DC output voltage, the DC output voltage having the same polarity as that of the previous nozzle detection is output from the bipolar output DC power supply unit 11 to the charging electrode 12 to perform ink droplet detection processing. In FIG. 4, as shown in FIG. 4B, the detected voltage is not properly discharged at the (n + 1) th nozzle, and an ink droplet ejection abnormality occurs, and as shown in FIG. This shows a state where a DC output voltage having the same polarity (minus) as that at the time of detection of the (n + 1) th nozzle is output to the charging electrode 12 at the time of detecting the nozzle No. 1.

  That is, for each nozzle to be inspected, the capacitor 14 is repeatedly charged, discharged, charged, and so on by the charge induced in the detection electrode 13, and the output of the amplifier circuit 15 is output by repeating the charging / discharging of the capacitor 14. The detection voltage to be repeated rises, falls, rises,...

  Therefore, the DC output voltage having the same polarity as the DC output voltage in the ink droplet detection process of the previous nozzle in the ink droplet detection process in the nozzle next to the nozzle having the ink droplet ejection abnormality is supplied from the bipolar output DC power supply unit 11. When the ink droplet ejection that is output to the charging electrode 12 and the next inspection target is normal, as shown in FIG. 4B, the capacitor 14 that has not been charged or discharged due to abnormal ink droplet ejection is appropriate. The ink droplet detection process can be performed appropriately by being discharged or charged.

  Then, the controller unit sequentially performs the ink droplet detection process for a plurality of nozzles of the ink head 2, performs the ink droplet detection process for all the nozzles, and results of the ink droplet detection process for all the nozzles. If the number of nozzles having ink droplet ejection abnormalities exceeds a preset number of cleanings, a cleaning mechanism (not shown) is driven to perform cleaning of all nozzles. If the number of nozzles with abnormal ink droplet ejection is equal to or less than the preset number of cleanings, the controller unit ends the ink droplet detection process without cleaning the nozzles, and performs the next image formation. continue.

  Then, as described above, in the ink droplet detection process, the polarity of the DC output voltage output from the bipolar output DC power supply unit 11 is alternated for each nozzle to be inspected, and the ink droplets Ti ejected from the nozzles in sequence. When charged in reverse polarity, as shown in FIG. 5, in the case of the non-contact method in which the nozzle is ejected so as to pass through the vicinity of the detection electrode 13, the positively charged ink droplets Ti ejected from the nozzle and the negative polarity are negatively charged. Charged ink droplets Ti are bonded to each other, increasing the weight, increasing the sedimentation speed, and preventing the ink droplets Ti from floating in the air and sticking to the inside of the inkjet printer 1 indefinitely. can do. Therefore, the reliability of the inkjet printer 1 can be improved.

  In the above description, the non-contact type case where the ink droplets are detected by ejecting the ink droplets Ti from the nozzles of the ink head 2 so as to pass through the vicinity of the detection electrode 13 has been described. The same applies to the contact type in which the ink droplet Ti is ejected toward the detection electrode 13 to collide with the detection electrode 13.

  As described above, the ink droplet detection mechanism unit 3 of the ink jet printer 1 according to the present embodiment outputs a DC output voltage having a polarity alternating at a predetermined timing from the bipolar output DC power source 11 to the charging electrode 12, and the charging electrode 12 causes the ink to flow. Detection of the ink droplet Ti having the opposite polarity to the DC output voltage applied to the ink droplet ejected from the nozzle to be inspected among the plurality of nozzles of the head 2 by collision or passing of the charged ink droplet Ti. The controller 14 determines whether or not the ink droplet ejection from the nozzle to be inspected is appropriate based on the accumulated charge by accumulating the charge 14 having the opposite polarity to the charge of the ink droplet Ti generated on the electrode 13.

  Therefore, every time the nozzle to be inspected changes, the ink droplet detection processing can be continuously performed without performing the reset processing for discharging the capacitor 14, and the ink droplet detection processing time for all the nozzles can be shortened. it can.

  Further, in the ink jet printer 1 of the present embodiment, the controller unit causes the two-pole output DC power source 12 to output a DC voltage having an alternating polarity for each nozzle to be inspected.

  Therefore, every time the nozzle to be inspected changes, the ink droplet detection processing can be appropriately performed continuously without performing the reset processing for discharging the capacitor 14, and the ink droplet detection processing time for all the nozzles can be appropriately set. It can be shortened.

  Further, in the ink jet printer 1 of this embodiment, when the controller unit determines that the ink droplet ejection of the nozzle to be inspected is inappropriate, the ink droplet ejection is determined to be inappropriate as the DC voltage for the next nozzle to be inspected. A DC voltage having the same polarity as the DC voltage applied to the nozzle is output to the bipolar output DC power source 12.

  Therefore, even when the charge of the capacitor 14 is not discharged or not charged due to improper ink droplet ejection, the next nozzle can be appropriately detected without performing a reset process for discharging the capacitor 14. The ink droplet detection processing time for all the nozzles can be further appropriately shortened.

  In addition, the inkjet printer 1 of the present embodiment includes a cleaning mechanism unit that cleans the nozzles. When the controller unit determines that ink droplet ejection is inappropriate for a predetermined number of nozzles or more, the nozzles are provided in the cleaning mechanism unit. I'm cleaning.

  Therefore, the ink droplet ejection performance of the nozzle can be ensured appropriately.

  The invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to that described in the above embodiments, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

  The present invention can be used for an ink droplet detection device, an ink jet printer, an ink droplet detection method, an ink droplet detection program, and a recording medium that perform ink droplet detection processing of each nozzle of an ink head that ejects ink.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Ink head 3 Ink droplet detection mechanism part 11 Bipolar output DC power supply 12 Charged electrode 12a Passing area | region 13 Detection electrode 14 Capacitor 15 Amplifier circuit Ti Ink droplet

JP-A-11-170569

Claims (6)

An ink head having a plurality of nozzles for ejecting ink droplets;
Power supply means for outputting a DC voltage whose polarity alternates at each predetermined timing;
Among the plurality of nozzles of the ink head, an electric charge that is arranged in the vicinity of an ink droplet ejected from a nozzle to be inspected and has a polarity opposite to the direct current voltage is applied to the ink droplet by a direct current voltage supplied from the power supply means. A charged electrode,
A detection electrode that generates a charge having a polarity opposite to the charge of the ink droplet when the ink droplet charged with the charged electrode collides or passes nearby;
Charge storage means for sequentially storing charges generated in the detection electrodes;
Determination means for determining the suitability of ink droplet ejection from the nozzle based on the accumulated charge of the charge accumulation means;
An ink droplet detection device comprising:   2. The ink droplet detection apparatus according to claim 1, further comprising a control unit that causes the power source unit to output a DC voltage having an alternating polarity for each nozzle to be inspected.   If the determination means determines that the ink droplet ejection of the nozzle to be inspected is inappropriate, the control means uses the direct current to the nozzle for which the ink droplet ejection is determined to be inappropriate as the DC voltage for the next nozzle to be inspected. 3. The ink droplet detection apparatus according to claim 2, wherein a DC voltage having the same polarity as the voltage is output to the power supply means. The ink droplet detection device includes nozzle cleaning means for cleaning the nozzle,
3. The ink droplet according to claim 2, wherein the control unit causes the nozzle cleaning unit to clean the nozzle when the determination unit determines that the ink droplet ejection is inappropriate for a predetermined number of nozzles or more. Detection device.   In an ink jet printer that forms an image on a recording medium by moving an ink head having a plurality of nozzles for ejecting ink droplets in the main scanning direction and ejecting ink droplets from the nozzles, ink droplet ejection from the nozzles is performed. 5. An ink jet printer comprising the ink droplet detection device according to claim 1 as an ink droplet detection device for checking suitability. A power supply output processing step of outputting a DC voltage of a predetermined polarity at a predetermined timing from a power supply means capable of outputting a DC voltage of a predetermined voltage of different polarity;
Among the plurality of nozzles of the ink head, a charge having a polarity opposite to that of the DC voltage is generated by a DC voltage output in the power output process step from a charging electrode arranged in the vicinity of an ink droplet ejected from a nozzle to be inspected. An ink droplet charging process step to be applied to the ink droplets;
A detection charge generation processing step for causing the detection electrode to generate a charge having a polarity opposite to the charge of the ink droplet when the ink droplet to which the charge has been applied in the ink droplet charging processing step collides or passes nearby;
A determination processing step for determining the suitability of ink droplet ejection from the nozzle based on the accumulated charge of the charge accumulating means for accumulating the charge generated in the detection electrode;
An ink droplet detection method characterized by comprising:

Images