JP2005262867A - Liquid discharge inspection apparatus, liquid discharge inspection method, liquid discharge apparatus, inkjet printer, program and liquid discharge system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid discharge inspection apparatus which simply executes discharge inspection of a liquid discharge part. <P>SOLUTION: The liquid discharge inspection apparatus for carrying out discharge inspection of a liquid at the liquid discharge part is equipped with a sensing part formed by a conductor. When an induction current is generated at the sensing part by the charged liquid discharged from the liquid discharge part, the liquid discharge inspection apparatus judges that there is a discharge of the liquid. When the induction current is not generated at the sensing part, the liquid discharge inspection apparatus judges that there is no discharge of the liquid. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid ejection inspection apparatus, a liquid ejection inspection method, a liquid ejection apparatus, an ink jet printer, a program, and a liquid ejection system that perform a liquid ejection inspection from a liquid ejection section.

  As a liquid ejecting apparatus, an ink jet printer that performs printing by ejecting ink onto various media such as paper, cloth, and film is known. This ink jet printer performs color printing by ejecting ink of each color such as cyan (C), magenta (M), yellow (Y), and black (K) to form dots on a medium. Ink is ejected by nozzles.

  However, in such an ink jet printer, the nozzles may be clogged due to ink sticking or the like, and the ink may not be ejected normally. Thus, when ink is not ejected normally from the nozzles, dots cannot be formed properly on the medium, which causes a problem that images are not printed neatly. For this reason, it is necessary to periodically inspect the ejection of the nozzles to inspect whether the ink is ejected normally.

In view of this, various methods for inspecting whether ink is normally ejected from nozzles have been proposed. Specifically, a method for inspecting ink ejection failure by detecting whether or not the ink ejected from the nozzle blocks a laser beam has been proposed (see Patent Document 1).
JP 2002-361863 A

  However, such an inspection method requires a large-scale laser irradiation device to irradiate a laser beam, and it is extremely difficult to secure a space for installing such a laser irradiation device inside the printer. There was also a problem that caused a significant cost increase. For this reason, there has been a demand for a more compact and compact discharge inspection apparatus that does not require much installation space and does not cause a significant increase in cost.

  The present invention has been made in view of such circumstances, and an object of the present invention is to enable a discharge inspection to be easily performed in a discharge portion of a liquid such as ink.

The main invention for achieving the above object is a liquid ejection inspection apparatus for performing a liquid ejection inspection in a liquid ejection section.
A sensing unit provided in a non-contact state with the liquid ejection unit;
When an induced current is generated in the sensing unit due to the charged liquid discharged from the liquid discharge unit, it is determined that there is liquid discharge,
In the liquid discharge inspection apparatus, it is determined that no liquid is discharged when the induced current is not generated in the sensing unit.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

  According to the present invention, the discharge inspection of the liquid discharge unit can be easily performed.

=== Summary of disclosure ===
At least the following matters will become apparent from the description of the present specification and the accompanying drawings.

In a liquid discharge inspection apparatus for performing a liquid discharge inspection in a liquid discharge unit,
A sensing unit provided in a non-contact state with the liquid ejection unit;
When an induced current is generated in the sensing unit due to the charged liquid discharged from the liquid discharge unit, it is determined that there is liquid discharge,
A liquid ejection inspecting apparatus according to claim 1, wherein when the induced current is not generated in the sensing unit, it is determined that no liquid is ejected.
In such a liquid discharge inspection device, it is easy to determine whether or not liquid has been discharged from the liquid discharge unit by detecting the induced current generated in the sensing unit by the charged liquid discharged from the liquid discharge unit. Can be inspected.

  In such a liquid discharge inspection apparatus, when performing the discharge inspection, a liquid droplet may be discharged as the liquid from the liquid discharge portion. If liquid droplets are ejected in this way, the amount of liquid used can be reduced during ejection inspection.

  In addition, such a liquid ejection inspection apparatus may include a detection unit that detects the induced current generated in the sensing unit. If such a detection unit is provided, the induced current generated in the sensing unit can be easily detected.

  Further, in such a liquid ejection inspection device, the current level of the induced current detected by the detection unit is compared with a predetermined reference level to determine whether the induced current is generated in the sensing unit. You may judge. By making such a determination, it can be easily determined whether or not the induced current is generated in the sensing unit.

  In the liquid discharge inspection apparatus, a voltage may be applied to the sensing unit in order to charge the liquid discharged from the liquid discharge unit. When the voltage is applied to the sensing unit in this way, the liquid ejected from the liquid ejecting unit can be easily charged.

  In the liquid discharge inspection apparatus, the liquid discharged from the liquid discharge unit may be charged by frictional charging. If charging is performed by frictional charging as described above, the liquid can be easily charged.

  In addition, such a liquid discharge inspection apparatus may include an electrode unit to which a voltage is applied in order to charge the liquid discharged from the liquid discharge unit. By providing such an electrode part, the liquid discharged from the liquid discharge part can be easily charged.

  In such a liquid ejection inspection apparatus, the sensing unit may be formed of a wire. Thus, if the sensing part is formed of a wire, it can be easily sensed whether or not liquid is ejected from the liquid ejection part.

  In the liquid discharge inspection apparatus, the sensing unit may be formed in a coil shape. Thus, if the sensing part is formed in a coil shape, the liquid ejected from the liquid ejecting part can be sensed with higher sensitivity.

  Further, in such a liquid ejection inspection device, the surface of the sensing unit may be subjected to water repellent treatment. If the water repellent treatment is performed on the surface of the sensing unit in this way, the adhesion of liquid to the surface of the sensing unit can be reduced.

  In such a liquid discharge inspection apparatus, the liquid discharged from the liquid discharge unit may be ink. It is possible to easily execute the discharge inspection of the liquid discharge unit that discharges such ink.

In a liquid discharge inspection apparatus for performing a liquid discharge inspection in a liquid discharge unit,
A sensing unit provided in a non-contact state with the liquid ejection unit;
When an induced current is generated in the sensing unit due to the charged liquid discharged from the liquid discharge unit, it is determined that there is liquid discharge,
If the induced current does not occur in the sensing unit, determine that there is no liquid discharge,
When performing the inspection, a liquid droplet is discharged from the liquid discharge unit as the liquid,
A detection unit for detecting the induced current generated in the sensing unit;
The signal level of the output signal output from the detection unit is compared with a predetermined reference level to determine whether the induced current is generated in the sensing unit,
In order to charge the liquid ejected from the liquid ejection unit, a voltage is applied to the sensing unit,
The sensing part is formed of a wire;
Water repellent treatment is applied to the surface of the sensing unit,
A liquid discharge inspection apparatus, wherein the liquid discharged from the liquid discharge unit is ink.

A method for performing a liquid discharge inspection in a liquid discharge unit,
When an induced current is generated by the charged liquid discharged from the liquid discharge unit to the sensing unit provided in a non-contact state with the liquid discharge unit, it is determined that there is liquid discharge,
A liquid discharge inspection method, wherein when no induced current is generated in the sensing unit, it is determined that no liquid is discharged.

In a liquid ejection apparatus provided with a liquid ejection unit that ejects liquid to a medium,
A sensing unit provided in a non-contact state with the liquid ejection unit;
When an induced current is generated in the sensing unit due to the charged liquid discharged from the liquid discharge unit, it is determined that there is liquid discharge,
A liquid ejection apparatus comprising: a liquid ejection determination unit that determines that no liquid is ejected when the induced current is not generated in the sensing unit.

In an inkjet printer having an ink ejection unit that ejects ink onto a medium,
A sensing unit provided in a non-contact state with the ink ejection unit;
When an induced current is generated in the sensing unit due to the charged ink ejected from the ink ejection unit, it is determined that there is ink ejection,
An ink jet printer comprising: an ink ejection determination unit that determines that no ink is ejected when the induced current is not generated in the sensing unit.

A program executed in a liquid discharge inspection apparatus that performs liquid discharge inspection in a liquid discharge unit,
Discharging the charged liquid from the liquid discharge unit;
When an induced current is generated by the charged liquid discharged from the liquid discharge unit to the sensing unit provided in a non-contact state with the liquid discharge unit, it is determined that there is liquid discharge,
And a step of determining that no liquid is ejected when the induced current is not generated in the sensing unit.

In a liquid ejection system comprising a computer main body and a liquid ejection device connectable to the computer main body,
The liquid ejection device includes a liquid ejection unit that ejects liquid onto a medium;
A sensing unit provided in a non-contact state with the liquid ejection unit;
When an induced current is generated in the sensing unit due to the charged liquid discharged from the liquid discharge unit, it is determined that there is liquid discharge,
A liquid ejection system comprising: a liquid ejection determination unit that determines that no liquid is ejected when no induced current is generated in the sensing unit.

=== Overview of Liquid Discharge Device ===
An embodiment of a liquid ejection apparatus according to the present invention will be described. Here, an ink jet printer will be described as an example of the liquid ejection apparatus according to the present invention.

<Liquid ejection device>
1 to 4 show the ink jet printer 1. FIG. 1 shows the appearance of the inkjet printer 1. FIG. 2 shows the internal configuration of the inkjet printer 1. FIG. 3 shows the transport section of the inkjet printer 1. FIG. 4 is a block diagram showing the system configuration of the inkjet printer 1.

  As shown in FIG. 1, the inkjet printer 1 has a structure for discharging a medium such as printing paper supplied from the back side from the front side, and an operation panel 2 and a paper discharge unit 3 are provided on the front side. The paper feeding unit 4 is provided on the back side. Various operation buttons 5 and display lamps 6 are provided on the operation panel 2. Further, the paper discharge unit 3 is provided with a paper discharge tray 7 that closes the paper discharge port when not in use. The paper feed unit 4 is provided with a paper feed tray 8 that holds cut paper (not shown). Note that the inkjet printer 1 may include a paper feed structure that can print not only on single-sheet-like printing paper such as cut paper but also on continuous media such as roll paper.

  Inside the ink jet printer 1, a carriage 41 is provided as shown in FIG. The carriage 41 is provided so as to be relatively movable along a predetermined direction (in the present embodiment, the scanning direction in the figure). Around the carriage 41, a carriage motor (hereinafter also referred to as a CR motor) 42, a pulley 44, a timing belt 45, and a guide rail 46 are provided. The carriage motor 42 is constituted by a DC motor or the like, and functions as a drive source for relatively moving the carriage 41 along the predetermined direction. The timing belt 45 is connected to the carriage motor 42 via the pulley 44, and a part of the timing belt 45 is connected to the carriage 41. The carriage 41 is relatively driven along the predetermined direction by the rotation of the carriage motor 42. Move to. The guide rail 46 guides the carriage 41 along the predetermined direction. In addition, around the carriage 41, a linear encoder 51 that detects the position of the carriage 41, a conveyance roller 17 </ b> A for conveying the medium S along a direction that intersects the moving direction of the carriage 41, and this conveyance A paper conveyance motor 15 that rotates the roller 17A is provided.

  On the other hand, the carriage 41 is provided with an ink cartridge 48 that stores various inks, and a head 21 that performs printing on the medium S. The ink cartridge 48 contains, for example, each color ink such as yellow (Y), magenta (M), cyan (C), black (K), and is detachable from a cartridge mounting portion provided on the carriage 41. It is installed. On the other hand, the head 21 performs printing by ejecting ink onto the medium S in this embodiment. For this purpose, the head 21 is provided with a number of nozzles for ejecting ink. The ink ejection mechanism of the head 21 will be described in detail later.

  In addition, a cleaning unit 30 for eliminating clogging of the nozzles of the head 21 is provided inside the ink jet printer 1. The cleaning unit 30 includes a pump device 31 and a capping device 35. The pump device 31 is a device that sucks out ink from the nozzles in order to eliminate clogging of the nozzles of the head 21, and is operated by a pump motor (not shown). On the other hand, the capping device 35 seals the nozzles of the head 21 when printing is not performed (for example, during standby) in order to prevent clogging of the nozzles of the head 21.

  Next, the configuration of the transport unit of the inkjet printer 1 will be described. As shown in FIG. 3, the transport unit includes a paper insertion port 11A and a roll paper insertion port 11B, a paper feed motor (not shown), a paper feed roller 13, a platen 14, and a paper transport motor (hereinafter referred to as PF). (Also referred to as a motor) 15, a transport roller 17A, a paper discharge roller 17B, a free roller 18A, and a free roller 18B.

  The paper insertion slot 11A is where the paper S, which is a medium, is inserted. The paper feed motor (not shown) is a motor that transports the paper S inserted into the paper insertion slot 11A into the printer 1, and includes a pulse motor or the like. The paper feed roller 13 is a roller that automatically conveys the medium S inserted into the paper insertion slot 11A into the printer 1 in the direction of arrow A in the figure (the direction of arrow B in the case of roll paper). Driven by. The paper feed roller 13 has a substantially D-shaped cross section. Since the circumferential length of the circumferential portion of the feed roller 13 is set to be longer than the transport distance to the PF motor 15, the medium S can be transported to the PF motor 15 using this circumferential portion. The rotational driving force of the paper feed roller 13 and the frictional resistance of the separation pad (not shown) prevent a plurality of media S from being fed at a time.

  The platen 14 is a support unit that supports the paper S during printing. The PF motor 15 is a motor that feeds, for example, paper as the medium S in the paper conveyance direction, and is configured by a DC motor. The transport roller 17 </ b> A is a roller that feeds the paper S transported into the printer 1 by the paper feed roller 13 to a printable area, and is driven by the PF motor 15. The free roller 18A is provided at a position facing the transport roller 17A, and presses the paper S toward the transport roller 17A by sandwiching the paper S with the transport roller 17A.

  The paper discharge roller 17 </ b> B is a roller for discharging the printed paper S to the outside of the printer 1. The paper discharge roller 17B is driven by the PF motor 15 by a gear (not shown). The free roller 18B is provided at a position facing the paper discharge roller 17B, and presses the paper S toward the paper discharge roller 17B by sandwiching the paper S between the paper discharge roller 17B.

<System configuration>
Next, the system configuration of the inkjet printer 1 will be described. As shown in FIG. 4, the inkjet printer 1 includes a buffer memory 122, an image buffer 124, a system controller 126, a main memory 127, and an EEPROM 129. The buffer memory 122 receives and temporarily stores various data such as print data transmitted from the host computer 140. The image buffer 124 acquires the received print data from the buffer memory 122 and stores it. The main memory 127 is composed of a ROM, a RAM, and the like.

  On the other hand, the system controller 126 reads the control program from the main memory 127 and controls the entire printer 1 according to the control program. The system controller 126 of this embodiment includes a carriage motor control unit 128, a conveyance control unit 130, a head drive unit 132, a rotary encoder 134, and a linear encoder 51. The carriage motor control unit 128 drives and controls the rotation direction, rotation speed, torque, and the like of the carriage motor 42. Further, the head drive unit 132 performs drive control of the head 21. The conveyance control unit 130 controls various drive motors arranged in the conveyance system such as the paper conveyance motor 15 that rotationally drives the conveyance roller 17A.

  The print data sent from the host computer 140 is temporarily stored in the buffer memory 122. Necessary information is read from the print data stored here by the system controller 126. Based on the read information, the system controller 126 refers to the output from the linear encoder 51 and the rotary encoder 134 and controls the carriage motor control unit 128, the conveyance control unit 130, and the head drive unit 132 according to the control program. Control each one.

  The image buffer 124 stores print data of a plurality of color components received by the buffer memory 122. The head drive unit 132 acquires print data of each color component from the image buffer 124 according to a control signal from the system controller 126, and drives and controls the nozzles of each color provided in the head 21 based on this print data.

  In addition to the above, the inkjet printer 1 according to the present embodiment includes a detection unit 80 and an A / D conversion unit 88. The detection unit 80 and the A / D conversion unit 88 will be described in detail later.

<Head>
FIG. 5 is a diagram showing the arrangement of the ink nozzles provided on the lower surface of the head 21. On the lower surface of the head 21, as shown in the figure, nozzles comprising a plurality of nozzles # 1 to # 180 for each color of yellow (Y), magenta (M), cyan (C), and black (K). A column 211 is provided. The yellow (Y), magenta (M), cyan (C), and black (K) nozzle rows 211 correspond to the liquid ejection unit of the present invention.

  The nozzles # 1 to # 180 of each nozzle row 211 are arranged linearly along the paper S conveyance direction. Each nozzle row 211 is arranged in parallel with a space between each other along the moving direction (scanning direction) of the head 21. Each nozzle # 1 to # 180 is provided with a piezo element (not shown) as a drive element for ejecting ink droplets.

  When a voltage having a predetermined time width is applied between the electrodes provided at both ends of the piezoelectric element, the piezoelectric element expands according to the voltage application time and deforms the side wall of the ink flow path. As a result, the volume of the ink flow path contracts according to the expansion and contraction of the piezo element, and the ink corresponding to the contraction is ejected from the nozzles # 1 to # 180 of each color as ink droplets.

  FIG. 6 shows the drive circuit 220 for each of the nozzles # 1 to # 180. The drive circuit 220 includes an original drive signal generator 221 and a plurality of mask circuits 222 as shown in FIG. The original drive signal generator 221 generates an original signal ODRV that is used in common by the nozzles # 1 to # 180. This original signal ODRV has two pulses, a first pulse W1 and a second pulse W2, within the main scanning period for one pixel (within the time during which the carriage 41 crosses the interval of one pixel), as shown in the lower part of the figure. It is a signal containing. The original signal ODRV generated by the original drive signal generator 221 is output to each mask circuit 222.

  The mask circuit 222 is provided corresponding to a plurality of piezo elements that drive the nozzles # 1 to # 180 of the head 21, respectively. Each mask circuit 222 receives the original signal ODRV from the original signal generator 221 and the print signal PRT (i). The print signal PRT (i) is pixel data corresponding to a pixel, and is a binary signal having 2-bit information for one pixel. Each bit corresponds to the first pulse W1 and the second pulse W2, respectively. The mask circuit 222 is a gate for blocking or passing the original signal ODRV in accordance with the level of the print signal PRT (i). That is, when the print signal PRT (i) is at level “0”, the pulse of the original signal ODRV is cut off, while when the print signal PRT (i) is at level “1”, the corresponding pulse of the original signal ODRV is passed as it is. Then, the drive signal DRV is output toward the piezoelectric elements of the nozzles # 1 to # 180. The piezo elements of the nozzles # 1 to # 180 are driven based on the drive signal DRV from the mask circuit 222 to discharge ink.

  FIG. 7 is a timing chart of the original signal ODRV, the print signal PRT (i), and the drive signal DRV (i) showing the operation of the original drive signal generator 221. As shown in the figure, the original signal ODRV sequentially generates a first pulse W1 and a second pulse W2 in each pixel section T1, T2, T3, T4. Note that the pixel section has the same meaning as the movement section of the carriage 41 for one pixel.

  Here, when the print signal PRT (i) corresponds to the 2-bit pixel data “10”, only the first pulse W1 is output in the first half of one pixel section. Thereby, small ink droplets are ejected from the nozzles # 1 to # 180, and small dots (small dots) are formed on the medium. When the print signal PRT (i) corresponds to 2-bit pixel data “01”, only the second pulse W2 is output in the second half of one pixel interval. As a result, medium-sized ink droplets are ejected from the nozzles # 1 to # 180, and medium-sized dots (medium dots) are formed on the medium. When the print signal PRT (i) corresponds to the 2-bit pixel data “11”, the first pulse W1 and the second pulse W2 are output in one pixel section. Thus, large size ink droplets are ejected from the nozzles # 1 to # 180, and large size dots (large dots) are formed on the medium. As described above, the drive signal DRV (i) in one pixel section is shaped to have three different waveforms according to three different values of the print signal PRT (i), and based on these signals. The head 21 can form dots of three types of sizes and can adjust the amount of ink ejected in the pixel section. Further, when the print signal PRT (i) corresponds to the 2-bit pixel data “00” as in the pixel section T4, ink droplets are not ejected from the nozzles # 1 to # 180, and the medium has dot dots. Will not be formed.

  In the inkjet printer 1 according to the present embodiment, such a drive circuit 220 for the nozzles # 1 to # 180 is provided for each nozzle row 211, that is, yellow (Y), magenta (M), cyan (C), black ( K) is provided separately for each color, and the piezo elements are individually driven for each nozzle # 1 to 180 of each nozzle row 211.

=== Printing operation ===
Next, the printing operation of the above-described ink jet printer 1 will be described. Here, “bidirectional printing” will be described as an example. FIG. 8 is a flowchart showing an example of the processing procedure of the printing operation of the inkjet printer 1. Each process described below is executed by the system controller 126 reading a program stored in the main memory 127 or the EEPROM 129 and controlling each unit according to the program.

  Upon receiving print data from the host computer 140, the system controller 126 first performs a paper feed process to execute printing based on the print data (S102). The paper feed process is a process for supplying a medium to be printed, here, paper into the printer 1 and transporting it to a print start position (also referred to as a cue position). The system controller 126 rotates the paper feed roller 13 to send the paper to be printed to the transport roller 17A. The system controller 126 rotates the transport roller 17A to position the paper fed from the paper feed roller 13 at the print start position.

  Next, the system controller 126 executes a printing process for printing the medium by moving the carriage 41 relative to the medium. Here, first, forward printing is performed in which ink is ejected from the head while the carriage 41 is moved in one direction along the guide rail 46 (S104). The system controller 126 drives the carriage motor 32 to move the carriage 41 and drives the head based on the print data to eject ink. The ink ejected from the head 21 reaches the paper and is formed as dots.

  After printing is performed in this manner, next, a carrying process for carrying the medium by a predetermined amount is executed (S106). In this transport process, the system controller 126 drives the transport motor 15 to rotate the transport roller 17A and transports the paper by a predetermined amount relative to the head 21 in the transport direction. By this carrying process, the head 21 can print in an area different from the previously printed area.

  After carrying out the carrying process in this way, it is determined whether or not to discharge paper (S108). Here, if there is no other data to be printed on the paper being printed, a paper discharge process is executed (S116). On the other hand, if there is other data to be printed on the paper being printed, the return pass printing is executed without performing the paper discharge process (S110). In this backward printing, printing is performed by moving the carriage 41 along the guide rail 46 in the direction opposite to the previous forward printing. Again, the system controller 126 drives the carriage motor 42 to rotate in the opposite direction to move the carriage 41 and drives the head 21 based on the print data to eject ink and perform printing.

  After performing the return pass printing, a carrying process is executed (S112), and then a paper discharge determination is made (S114). Here, if there is other data to be printed on the paper being printed, the process returns to step S104 without performing the paper discharge process, and the forward printing is executed again (S104). On the other hand, if there is no other data to be printed on the paper being printed, a paper discharge process is executed (S116).

  After the paper discharge process is performed, next, a print end determination is performed to determine whether or not to end printing (S118). Here, based on the print data from the host computer 140, it is checked whether there is any paper to be printed next. If there is a sheet to be printed next, the process returns to step S102, the paper feed process is executed again, and printing is started. On the other hand, if there is no paper to be printed next, the printing process ends.

=== Liquid ejection inspection apparatus ===
An embodiment of a liquid discharge inspection apparatus according to the present invention will be described. Here, a case where the liquid discharge inspection apparatus according to the present invention is mounted on an ink jet printer (liquid discharge apparatus) will be described as an example.

<Outline of inspection device>
9 and 10 schematically illustrate a liquid ejection inspection apparatus 60 mounted on the ink jet printer 1 of the present embodiment and an inspection method thereof. FIG. 9 is an explanatory diagram for explaining the configuration of the liquid ejection inspection apparatus 60, and FIG. 10 is an explanatory diagram for explaining the inspection principle of the liquid ejection inspection apparatus 60.

  As shown in FIG. 9, the liquid ejection inspection apparatus 60 includes a sensing unit 70 disposed at a position that can face the head 21, and a detection unit 80 connected to the sensing unit 70. The sensing unit 70 is made of a conductive wire such as metal, and is arranged in parallel with the head 21 in a tensioned state. When the carriage 41 moves, the sensing unit 70 is disposed so as to face the head 21 in a non-contact state with a gap D between the head 21 and the sensing unit 70. The distance D between the head 21 and the sensing unit 70 is set to 1 mm, for example.

  Further, a power source (not shown) is connected to the sensing unit 70 via a protective resistor R1, and a high voltage such as 100 V (volts) is applied from the power source.

  On the other hand, the detection unit 80 detects a current generated in the sensing unit 70. In the present embodiment, the detection unit 80 is configured by a detection circuit including a capacitor C, an input resistor R2, a feedback resistor R3, and an operational amplifier Amp. The capacitor C serves to input the current fluctuation as an electric signal to the operational amplifier Amp via the input resistor R2 when the current fluctuation occurs in the sensing unit 70. The operational amplifier Amp serves as an amplifier circuit that amplifies and outputs a signal input through the capacitor C. The output signal from the operational amplifier Amp is A / D converted from an analog signal to a digital signal by an A / D converter 88 (see FIG. 4), for example, and is sent to the system controller 126 in an appropriate form such as digital data. Is output.

  Actually, when performing an ejection test, an operation of ejecting ink from the nozzles # 1 to # 180 of the head 21 toward the sensing unit 70 or the vicinity thereof is executed. FIG. 10 illustrates how ink is ejected from a nozzle with the head 21 toward the vicinity of the sensing unit 70. Here, the ink droplets Ip are ejected from the nozzles # 1 to # 180 of the head 21 only once, that is, one droplet.

  At this time, a very high voltage such as 100 V (volts) is applied to the sensing unit 70 by a supply voltage from the power source. As a result, a very strong electric field is formed between the head 21 and the sensing unit 70. In such a state, when the ink droplet Ip is ejected from the nozzles # 1 to # 180, the ejected ink droplet Ip is charged.

  The charged ink droplets Ip discharged from the nozzles # 1 to # 180 pass in the vicinity of the sensing unit 70. When the charged ink droplet Ip passes near the sensing unit 70, an induced current is generated in the sensing unit 70 along a predetermined direction. This induced current is considered to be generated by electrostatic induction or the like as the charged ink droplet Ip approaches.

  When an induced current is generated in the sensing unit 70 as described above, a variation occurs in the current input to the detection unit 80, and this current variation is input as an electric signal to the operational amplifier Amp via the input resistor R2. The signal input to the operational amplifier Amp is amplified and output toward the system controller 126 and the like. Thus, when an induced current is generated in the sensing unit 70, this is detected by the detection unit 80, and the detection signal is converted from an analog signal into digital data or the like through the A / D conversion unit 88 (see FIG. 4). And output to the system controller 126.

  The system controller 126 determines, for example, whether ink has been ejected from the data from the detection unit 80 by comparing the current level, that is, the magnitude of the induced current generated in the sensing unit 70 with a predetermined reference level. To do. The predetermined reference level is set to an appropriate value so that no error occurs in the ejection inspection. Information regarding the predetermined reference level is stored as data in an appropriate storage unit such as a memory such as the main memory 127 or the EEPROM 129. When comparing the current level of the induced current with a predetermined reference level, the system controller 126 acquires information on the reference level from an appropriate storage unit such as the main memory 127 or the EEPROM 129.

  On the other hand, when the ink droplet Ip is not normally ejected from the nozzles # 1 to # 180, since the charged ink droplet Ip does not pass through the vicinity of the sensing unit 70, an induced current is generated in the sensing unit 70. do not do. For this reason, the detection unit 80 does not detect any current fluctuation, so it is possible to easily check whether ink is normally ejected for each of the nozzles # 1 to # 180.

  Note that it is preferable that the size of the ink droplets Ip ejected from the nozzles # 1 to # 180 during ejection inspection is as large as possible. That is, in the inkjet printer 1 of the present embodiment, the size is set to be approximately equal to the ink droplet Ip ejected to form the largest dot, for example, a large dot (“11”) on the medium. Is preferred. This is because if the size of the ink droplets Ip ejected from the nozzles # 1 to # 180 is large, the ink droplets ejected from the nozzles are more easily charged, and the sensing unit 70 generates the induced current more reliably. This is because the detection unit 80 can facilitate detection.

  Of course, it is not always necessary to set the size of the ink droplet Ip ejected during the ejection inspection to the size when forming the largest dot (large dot or the like), and the ink having a particularly large size only during the ejection inspection. The droplet Ip may be ejected, or a small ink droplet Ip may be ejected.

  In addition, the ink droplets Ip ejected from the nozzles # 1 to # 180 are not necessarily ejected toward the vicinity of the sensing unit 70, and may be ejected so as to contact the sensing unit 70. Also in this case, since the induced current is generated in the sensing unit 70 when the ink droplet Ip approaches the sensing unit 70, it is possible to check whether or not the ink droplet Ip has been ejected.

<Sensing part>
FIG. 11A and FIG. 11B show the sensing unit 70 of this embodiment in detail. FIG. 11A is a plan view showing the sensing unit 70, and FIG. 11B is a longitudinal sectional view of the sensing unit 70.

  As shown in FIG. 11A, the sensing unit 70 of the present embodiment is provided on a substrate 72 formed in a rectangular shape. The substrate 72 is a printed wiring board. The sensing unit 70 is installed across an opening 74 formed at the front end (lower end) of the substrate 72 along the length direction of the substrate 72, that is, the vertical direction here. Both ends of the sensing unit 70 are fixed to the inner edge of the opening 74 by fixing members 76, respectively. The sensing unit 70 is attached in a state of being stretched in the vertical direction on the opening 74 of the substrate 72. The ink droplets Ip ejected from the nozzles # 1 to # 180 of the head 21 pass through the side of the sensing unit 70 (here, the left side of the sensing unit 70), pass through the opening 74 of the substrate 72, and move downward. It is supposed to fall into.

  In this embodiment, circuit elements 82, 83, and 84 that constitute a protective resistor R 1, a capacitor C, an input resistor R 2, a feedback resistor R 3, an operational amplifier Amp, and the like that constitute the detection unit 80 are integrally mounted on the substrate 72. ing. Thus, the substrate 72 having the sensing unit 70 and the circuit elements 82, 83, and 84 serves as a discharge inspection unit for performing a discharge inspection of each nozzle # 1 to # 180 of the nozzle row 211 of the head 21.

<Sensor location>
FIG. 12 illustrates in detail the installation position of the sensing unit 70 of the present embodiment. As shown in the figure, the sensing unit 70 of the present embodiment is installed in an area An (hereinafter referred to as a non-printing area) that is out of a printing area Ap where ink is ejected from the nozzles # 1 to # 180 and printing is performed. Is done. In this non-printing area An, a pump device 31 that sucks out ink from the nozzles # 1 to # 180 is provided as a cleaning device for the nozzles # 1 to # 180 in order to eliminate clogging of the nozzles. The non-printing area An is provided with a capping device 35 that covers and caps the nozzles # 1 to # 180 of the head 21 when printing is not performed. The pump unit 31 and the capping device 35 constitute a cleaning unit 30. In addition, the cleaning unit 30 may be provided with various devices such as a wiping device for wiping off ink adhering excessively from the openings of the nozzles # 1 to # 180.

  In the present embodiment, the sensing unit 70 is provided in a position close to the printing area Ap in the non-printing area An, that is, between the printing area Ap and the cleaning unit 30 as shown in FIG. Thus, when the carriage 41 moves from the printing area Ap to the non-printing area An, it always passes above the sensing unit 70. Therefore, it is possible to perform the ink ejection inspection at any time during non-printing when the carriage 41 moves to the non-printing area An.

<Positional relationship between sensor and nozzle array>
FIG. 13 illustrates the positional relationship between the sensing unit 70 and the nozzle row 211 when the ejection inspection is performed. As shown in the figure, the sensing unit 70 is installed along the nozzle row 211 in parallel therewith, and its length L is set longer than the length of the nozzle row 211. Accordingly, the sensing unit 70 is formed to correspond to the nozzle row 211 for one row.

  When performing a discharge inspection, as shown in the figure, one nozzle row (here, nozzle row 211 (M)) of the plurality of nozzle rows 211 provided in the head 21 is detected by the sensing unit 70. Alignment is performed so as to be located right above the side (here, right above the left side in the figure). After the alignment is completed, ink is individually ejected from the nozzles # 1 to # 180 of the nozzle row 211 (here, the nozzle row 211 (M)) toward the side of the sensing unit, and the ejection test is performed. Is done.

  After the discharge inspection for one nozzle row 211 (here, the nozzle row 211 (M)) is completed, the carriage 41 moves to perform the discharge inspection for the next nozzle row 211 that has not yet been subjected to the discharge inspection. Then, the alignment between the sensing unit 70 and the nozzle row 211 (here, for example, the nozzle row 211 (Y)) to be subjected to the discharge inspection is performed again, and the discharge inspection is performed on the nozzle row 211. Is done. In this way, the discharge inspection is sequentially performed for each of the plurality of nozzle rows 211 provided in the head 21 one by one.

<Ink recovery unit>
The ink jet printer 1 according to the present embodiment includes an ink recovery unit 90 for recovering ink used for ejection inspection. FIG. 14 illustrates the ink collection unit 90. As shown in the figure, the ink collection unit 90 is installed, for example, below the substrate 72 on which the sensing unit 70 is provided, and is ejected from the nozzles # 1 to # 180 of the head 21 to the side of the sensing unit 70. The ink droplets Ip that have passed through and dropped through the opening 74 of the substrate 72 are received and collected. Thus, by collecting the ink used for the ejection inspection by the ink collecting unit 90, the inside of the printer 1 can be prevented from being soiled by the ink.

  In this embodiment, the ink collection unit 90 is formed as a concave container as shown in the figure. However, if the ink used for the ejection test is collected, for example, the platen 14 or the like is used. You may provide as a groove part etc. which were formed in the cross-sectional concave shape.

<Actual detection waveform>
FIG. 15 shows the waveforms of the drive signal output to the nozzle and the output signal from the detection unit 80 in order to eject ink during the ejection test. The upper waveform in the figure shows the waveform of the drive signal, and the lower waveform in the figure shows the waveform of the output signal of the detector 80. When a discharge inspection is performed for a certain nozzle, a driving pulse Wa for discharging an ink droplet once, that is, one droplet is supplied to a piezo element provided in a nozzle to be inspected as a driving signal as shown in FIG. Is output as

  On the other hand, when the ink is normally ejected from the nozzle to be inspected by such a drive signal, an induced current is generated in the sensing unit 70 by the ink droplet Ip ejected from the nozzle to be inspected, The induced current is detected by the detection unit 80, and a pulse Wb having a waveform that swings up and down as shown in the figure is output from the detection unit 80 as a detection signal. After the ink droplet Ip is ejected from the nozzle to be inspected, it takes a certain time until the induced current is generated, and there is a slight time difference until the generated induced current is detected and output by the detection unit 80. For this reason, the pulse of the detection signal output from the detection unit 80 is delayed in rising compared to the drive pulse of the drive signal.

  On the other hand, when ink is not normally ejected from the nozzles # 1 to # 180, no induced current is generated in the sensing unit 70. Therefore, the waveform of the output signal of the detection unit 80 is as shown in FIG. The waveform pulse Wb does not appear clearly.

  The ejection inspection is performed on a plurality of nozzles, for example, one nozzle row 211, that is, 180 nozzles # 1 to # 180. For this reason, as shown in the figure, the drive signal has a form in which a drive pulse for ejecting the ink droplet Ip to be inspected once (one droplet) is repeatedly output at a predetermined cycle T. Further, the output signal of the detection unit 80 corresponds to this drive signal, and if the ink is normally ejected from each of the nozzles # 1 to # 180, a waveform pulse with a predetermined period T as shown in FIG. Wb is formed. Here, the predetermined period T may be appropriately set on the basis of the time from when the drive pulse Wa is output to the nozzle to be inspected until the pulse Wb appears in the detection signal of the detection unit 80. By individually checking the detection signal from the detection unit 80 for each period T, it is possible to easily individually check whether or not the ink is normally ejected from the nozzles # 1 to # 180.

<Inspection procedure>
Next, the inspection procedure will be described. FIG. 16A is a flowchart illustrating an example of an inspection procedure in the inkjet printer 1 according to the present embodiment. In this embodiment, since the size of the sensing unit 70 corresponds to only one nozzle row 211, each nozzle row 211 (K), 211 (C), 211 (M), 211 (Y) The carriage 41 (head 21) is moved for each of the nozzles 211, and the ejection test is performed individually for each of the nozzle arrays 211 (K), 211 (C), 211 (M), and 211 (Y). Here, black (K) nozzle row 211 (K) → cyan (C) nozzle row 211 (C) → magenta (M) nozzle row 211 (M) → yellow (Y) nozzle row 211 (Y) The discharge inspection is performed in the order of.

  First, the cleaning frequency is initialized (S200). This is to set “0” to a counter that counts how many times the cleaning process has been performed during one ejection inspection, that is, how many times there is no ejection. Subsequently, a discharge inspection is performed on the black (K) nozzle row 211 (K) (S202). The ejection inspection for each nozzle row 211 (K), 211 (C), 211 (M), 211 (Y) performed here will be described in detail later. After the ejection inspection is completed, it is checked whether ink is ejected from the nozzles # 1 to # 180 of the black (K) nozzle row 211 (K) (S204). Here, if there is even one nozzle that does not discharge among the nozzles # 1 to # 180 of the black (K) nozzle row 211 (K), it is checked whether or not the number of cleanings has reached a specified number. (S220). Here, the prescribed number is a number that is considered that the ejection does not recover even if the cleaning process is repeated further. For example, when the number of times is three, when the number of times of cleaning is less than three, the nozzle row 211 is cleaned (S222). Here, the cleaning process is performed by the pump device 31 or the like, and may be performed only on the black (K) nozzle row 211 (K) or may be performed simultaneously with other nozzle rows. After completion of the cleaning process, the number of cleanings is increased by one (S224), and the ejection inspection of the nozzle row 211 is performed again.

  If it is determined in step S220 that the number of cleanings has reached the specified number, error processing is performed (S226), and the process ends. Here, the error processing may notify the user that there is a nozzle that does not discharge, and prompt the user to take more effective discharge recovery means. Further, the replacement of the head 21 including the nozzle that does not discharge may be promoted. Furthermore, nozzles that do not discharge may be stored, and printing may be continued by complementing with other nozzles without using the nozzles.

  On the other hand, if all of the nozzles # 1 to # 180 of the black (K) nozzle row 211 (K) are ejected, the process proceeds to step S206, and the cyan (C) nozzle row 211 (C) is ejected. An inspection is executed (S206). After completion of the ejection inspection, it is checked whether ink is ejected from nozzles # 1 to # 180 of the cyan (C) nozzle row 211 (C) (S208). If even one of the nozzles # 1 to # 180 in the cyan (C) nozzle row 211 (C) does not discharge, the process proceeds to a check of the number of cleanings in step S220.

  On the other hand, if all of the nozzles # 1 to # 180 of the cyan (C) nozzle row 211 (C) are discharged, the process proceeds to step S210, and the magenta (M) nozzle row 211 (M) is discharged. An inspection is executed (S210). After the ejection test is completed, it is checked whether ink is ejected from nozzles # 1 to # 180 of the magenta (M) nozzle row 211 (M) (S212). Here, if any one of the nozzles # 1 to # 180 in the magenta (M) nozzle row 211 (M) does not discharge, the process proceeds to a check of the number of cleanings in step S220.

  If all of the magenta (M) nozzle rows 211 (M) are discharged, the process proceeds to step S214, and a discharge test is performed on the yellow (Y) nozzle row 211 (Y) (S214). . After completion of the ejection test, it is checked whether ink is ejected from the nozzles # 1 to # 180 of the yellow (Y) nozzle row 211 (Y) (S216). Here, if there is any nozzle that does not discharge any of the nozzles # 1 to # 180 in the yellow (Y) nozzle row 211 (Y), the process proceeds to the check of the number of cleanings in step S220.

  On the other hand, when all of the nozzles # 1 to # 180 of the yellow (Y) nozzle row 211 (Y) are ejected, the nozzle rows 211 (K), 211 (C), 211 (M) of all colors, Since there is no ejection for each of the nozzles # 1 to # 180 of 211 (Y), it is determined that “all ejection is present” (S218), and the process ends.

  FIG. 16B is a flowchart when the cleaning process is performed for each nozzle row. First, the number of cleanings is initialized (S240). This is to set “0” to all the counters that count for each nozzle row how many cleaning processes have been performed during one ejection inspection, that is, how many times there has been no ejection. Subsequently, a discharge inspection is performed on the black (K) nozzle row 211 (K) (S242). After the ejection inspection is completed, it is checked whether ink is ejected from the nozzles # 1 to # 180 of the black (K) nozzle row 211 (K) (S244). Here, if even one of the nozzles # 1 to # 180 of the black (K) nozzle row 211 (K) does not discharge, the number of times of cleaning of the black (K) nozzle row 211 (K) is reached. It is checked whether or not the number reaches the specified number (S246). If the number of cleanings is less than the specified number, the black (K) nozzle row 211 (K) is cleaned (S248). After the cleaning process is completed, the number of cleanings of the black (K) nozzle row 211 (K) is increased by one (S250), and the ejection inspection of the black (K) nozzle row 211 (K) is performed again.

  If it is determined in step S246 that the number of cleanings has reached the specified number, error processing is performed (S282), and the process ends.

  On the other hand, if all of the nozzles # 1 to # 180 of the black (K) nozzle row 211 (K) are ejected, the process proceeds to step S252 to eject the cyan (C) nozzle row 211 (C). An inspection is executed (S252). After completion of the ejection inspection, it is checked whether ink is ejected from nozzles # 1 to # 180 of the cyan (C) nozzle row 211 (C) (S254). Here, if any one of the nozzles # 1 to # 180 of the cyan (C) nozzle row 211 (C) does not discharge, the number of times of cleaning the cyan (C) nozzle row 211 (C) is determined. It is checked whether or not the number reaches the specified number (S256). If the number of cleanings is less than the specified number, the cyan (C) nozzle row 211 (C) is cleaned (S258). After completion of the cleaning process, the number of times of cleaning of the cyan (C) nozzle row 211 (C) is increased by one (S260), and the ejection inspection of the cyan (C) nozzle row 211 (C) is performed again.

  If it is determined in step S256 that the number of cleanings has reached the specified number, error processing is performed (S282), and the process ends.

  Hereinafter, for magenta (M) and yellow (Y), the discharge inspection is performed in the same manner, and if there is any nozzle that does not discharge any of nozzles # 1 to # 180, the number of cleanings for that nozzle row is A check is made as to whether or not the specified number has been reached. If the number of cleanings is less than the specified number, a cleaning process is performed, the number of cleanings for the nozzle row is increased by one, and a discharge inspection is performed again. If the number of cleanings has reached the specified number, error processing is performed (S282) and the process ends.

  If all of the nozzles # 1 to # 180 of the yellow (Y) nozzle row 211 (Y) are ejected in step S274, the nozzle rows 211 (K), 211 (C), 211 (M) of all colors are ejected. ) And 211 (Y), since there is no ejection for each of the nozzles # 1 to # 180, it is determined that “all ejection is present” (S284), and the process ends.

  FIG. 17 is a flowchart for explaining the procedure of ejection inspection for each of the nozzle rows 211 (K), 211 (C), 211 (M), and 211 (Y). First, the head 21 is moved toward the sensing unit 70 (S302). Then, alignment between the nozzle row 211 to be inspected and the sensing unit 70 is performed (S304). Next, an initial value “1” is set to the variable “N” (S306), and the ink droplet Ip is delivered once (one droplet) from the “N” -th nozzle (nozzle #N) toward the sensing unit 70. A discharge operation is performed by performing a discharge operation (S308). After the end of ejection, a value of “N + 1” is set to the variable “N” (S310), and it is checked whether or not the variable “N” exceeds “180” that is the number of nozzles (S312). Here, when the variable “N” exceeds “180”, it is determined that the discharge inspection has been completed for all the nozzles, and the process is terminated.

  On the other hand, if the variable “N” does not exceed “180”, it is determined that all the nozzles # 1 to # 180 have not been inspected, and the process returns to step S308, and then the “N + 1” -th nozzle ( An ink ejection operation is performed for nozzle # N + 1) to perform ejection inspection (S308). Thereafter, the value of “N + 1” is set again to the variable “N” (S310), and each of the nozzles # 1 to # 180 is sequentially and individually set until the variable “N” exceeds “180” which is the number of nozzles. A discharge inspection is performed.

  In this embodiment, a series of these inspection processes are executed by the system controller 126 based on a program read from the main memory 127 or the EEPROM 129, or executed by an instruction from the host computer 140.

<Inspection timing>
The timing at which the discharge inspection is performed includes the following.

(1) During printing process Ejection inspection is executed at an appropriate timing during the printing process. For example, in the case of “bidirectional printing”, when the moving direction is changed, the carriage 41 moves to the standby position and the ejection inspection of the nozzles # 1 to # 180 is executed. As a result, it is possible to avoid the occurrence of defects in the printed image due to nozzle clogging during the printing process.

(2) When the power is turned on When the power is turned on, the discharge inspection is executed. In this case, in order to perform printing from now on, discharge inspection is executed when the printer (printing apparatus) is turned on, and discharge inspection of nozzles # 1 to # 180 is performed as one of the processes at the time of initialization processing of the printer 1. Execute. By executing the ejection inspection at such timing, the printing process can be smoothly executed without clogging the nozzles # 1 to # 180.

(3) At the time of paper feed During the operation of feeding the medium S to a predetermined position for printing, that is, at the time of paper feed, discharge inspection is executed. This is to check whether or not the ink is normally ejected when printing processing is to be performed on one medium S from now on, and each time the medium S is fed, the ejection inspection may be performed. In addition, the discharge inspection may be executed every predetermined number at an appropriate interval.

(4) At the time of acquiring print data When the printer 1 receives print data from a host computer 140 such as a personal computer, an ejection test is executed. That is, when printing data is received from the host computer 140 and printing is to be executed, it is checked whether or not ink is normally ejected. By executing the ejection inspection at such timing, the printing process can be smoothly executed without clogging of the nozzles # 1 to # 180.

  Note that the ejection inspection in the present invention is not necessarily performed at the timings (1) to (4) described above, and the ejection inspection is performed at a timing other than (1) to (4). Also good.

<Summary>
As described above, according to such a liquid discharge inspection apparatus, an operation of discharging charged ink from the nozzles # 1 to # 180 of the head 21 is performed, and whether or not an induced current is generated in the sensing unit 70 is determined. Since it is determined whether or not ink is ejected from the nozzles # 1 to # 180, the ejection inspection can be performed very easily. Therefore, the apparatus configuration is very compact, does not require a very large installation space, and does not incur a significant cost increase.

  In addition, by mounting such a liquid discharge inspection apparatus on the liquid discharge apparatus such as the ink jet printer 1 as described above, it is possible to perform a discharge inspection very easily, and it is possible to perform a discharge defect without much trouble. Can be easily solved.

  In addition, since it is not always necessary to bring the ink into contact with the sensing unit 70, it is possible to prevent the ink from being scattered or bounced by the ejection test, thereby preventing the inside of the apparatus from being soiled by the ink. it can.

  Further, since it is not always necessary to bring the ink into contact with the sensing unit 70, it is not necessary to precisely align the nozzle row and the sensing unit.

  Further, if the sensing unit 70 is formed of a wire as in the present embodiment, even if ink ejected from the nozzles # 1 to # 180 adheres to the sensing unit 70, it can be easily removed. Accordingly, a cleaning mechanism for removing ink from the sensing units 70 and 200 is not particularly required.

=== Other Configuration Examples of Inspection Apparatus ===
<Part 1: Use of triboelectric charging>
FIG. 18 illustrates another configuration example of the liquid ejection inspection apparatus according to the present invention. As shown in the figure, the inspection apparatus 100 applies a high voltage to the sensing unit 70 that generates an induced current, like the liquid ejection inspection apparatus described above (see FIGS. 9 to 10). Rather than charging the ink droplets Ip ejected from the nozzles # 1 to # 180, the ink droplets Ip ejected from the nozzles # 1 to # 180 naturally move when they leave the nozzles # 1 to # 180. The ink droplet Ip is charged by using a so-called triboelectric charging phenomenon. For this reason, the configuration of applying a high voltage to the sensing unit 70 in order to charge the ink droplet Ip is omitted.

As described above, by charging the ink droplets Ip ejected from the nozzles # 1 to # 180 using frictional charging, the configuration of the liquid ejection inspection apparatus 100 can be further simplified.
In this liquid discharge inspection apparatus, since a high voltage is not applied to the sensing unit 70, the capacitor C provided in the detection unit 80 of the liquid discharge inspection apparatus 60 (see FIGS. 9 to 10) described above is: Omitted from the configuration.

<Part 2; Installation of electrode part>
FIG. 19 illustrates another configuration example of the liquid ejection inspection apparatus according to the present invention. As shown in the figure, the inspection apparatus 110 includes an electrode unit 112 in addition to the sensing unit 70, and the electrode unit 112 charges the ink droplets Ip ejected from the nozzles # 1 to # 180. ing. As shown in the figure, the electrode portion 112 is made of a conductive wire such as a metal like the sensing portion 70, and is arranged in parallel with the head 21 in a tensioned state. . A power source (not shown) is connected to the electrode portion 112 via a protective resistor R1, and a high voltage such as 100 V (volt) is applied from the power source.

  Since such an electrode portion 112 is provided, an electric field is formed between the head 21 and the electrode portion 112, so that the ink droplets Ip are charged when they are separated from the nozzles # 1 to # 180. Can do.

  Next, the installation position of the electrode part 112 will be described. 20A and 20B show the installation positions of the electrode portions 112, respectively. 20A illustrates an example when the electrode unit 112 is disposed on the side of the sensing unit 70, and FIG. 20B illustrates an example when the electrode unit 112 is disposed above the sensing unit 70. It is.

  When the electrode unit 112 is disposed on the side of the sensing unit 70, the electrode unit 112 is disposed in parallel with the sensing unit 70 with a space between the sensing unit 70 as illustrated in FIG. 20A. . The ink droplets Ip ejected from the nozzles # 1 to # 180 fall downwardly between the electrode unit 112 and the sensing unit 70. If the electrode part 112 is arranged in this way, the electrode part 112 can be mounted on the substrate 72 like the sensing part 70.

  FIG. 21A is a plan view when the electrode unit 112 is mounted on the substrate 72 together with the sensing unit 70. FIG. FIG. 21B is a longitudinal sectional view when the electrode unit 112 is attached to the substrate 72 together with the sensing unit 70. As shown in these drawings, the electrode part 112 is installed in parallel with the sensing part 70 in such a manner that the electrode part 112 is stretched vertically above the opening of the substrate 72. Both end portions of the electrode portion 112 are fixed to the substrate 72 by a fixing member 114.

  On the other hand, when the electrode unit 112 is disposed above the sensing unit 70, similarly, as shown in FIG. 20B, the electrode unit 112 is spaced in parallel to the sensing unit 70 and parallel to the sensing unit 70. Be placed. However, in this case, the ink droplet Ip passes through the side of the electrode unit 112 and the sensing unit 70. As described above, the electrode unit 112 is installed above the sensing unit 70, whereby the electrode unit 112 can be brought closer to the head 21, whereby the electric field formed between the head 21 and the electrode unit 112 can be reduced. The ink droplet Ip discharged from the nozzles # 1 to # 180 of the head 21 can be easily charged by increasing the size. That is, the ink droplet Ip can be more easily detected by the detection unit 70.

  Note that it is preferable that the electrode portion 112 is located as close to the head 21 as possible. The closer the electrode portion 112 is to the head 21, the stronger the electric field between the electrode portion 112 and the head 21, and thus the sensing portion 70 can be more easily sensed.

=== Other Embodiments of Sensing Unit ===
22A and 22B are explanatory diagrams for explaining another embodiment of the sensing unit of the present invention. 22A is a plan view of the substrate 202 to which the sensing unit 200 is attached, and FIG. 22B is a longitudinal sectional view of the substrate 202 to which the sensing unit 200 is attached. The sensing unit 200 is provided in a coil shape on a substrate 72 formed in a rectangular shape, and spans an opening 204 formed at the tip of the substrate 72 so as to cross in the vertical direction. Has been. The ink droplets Ip ejected from the nozzles # 1 to # 180 of the head 21 fall downward through the central portion of the coil-shaped sensing unit 200.

  In this way, when the sensing unit 200 is formed in a coil shape and the ink droplet Ip falls on the central part of the coiled sensing unit 200, the sensing unit 200 is compared with the linear sensing unit 70 of the liquid ejection inspection apparatus described above. Since a larger induced current is generated, the ink droplet Ip can be sensed with higher accuracy.

  Furthermore, in the sensing unit 200, the greater the number of turns as a coil, the higher the sensing accuracy.

  Furthermore, FIG. 23A and FIG. 23B are explanatory drawings explaining other embodiment of the sensing part of this invention. FIG. 23A is a plan view of the substrate 212 to which the sensing unit 210 is attached, and FIG. 23B is a longitudinal sectional view of the substrate 212 to which the sensing unit 210 is attached. The sensing unit 210 is formed as a thin plate on the substrate 212. For example, the sensing unit 210 is formed by directly attaching a metal plate to the substrate 212, or by a film forming technique such as vapor deposition. Is done. In the vicinity of the sensing unit 210, there is provided a slit-shaped opening 214 through which the ink droplets Ip ejected from the nozzles # 1 to # 180 pass.

  It should be noted that the electrode portion 112 of the present invention is also formed by attaching a metal plate directly on the substrate 212 or the like as the sensing portion 210, or as a thin plate-like layer by a film forming technique such as vapor deposition. You may make it provide.

<Water repellent treatment>
The sensing units 70, 200, and 210 of the present invention may be subjected to a water repellent treatment on the surface thereof. As described above, if the surface of the sensing units 70, 200, and 210 is subjected to water repellent treatment, even when the ink droplets Ip ejected from the nozzles # 1 to # 180 contact the sensing units 70, 200, and 210. Ink can be easily removed from the surfaces of the sensing units 70, 200, and 210.

  Similarly, the surface of the electrode portion 112 of the present invention may be subjected to water repellent treatment. As described above, if the surface of the electrode portion 112 is also subjected to the water repellent treatment, even when the ink droplets Ip ejected from the nozzles # 1 to # 180 adhere to the electrode portion 112, the surface of the electrode portion 112 is removed. Ink can be easily removed.

  Examples of the method for performing the water repellent treatment include well-known methods including a method of providing a water repellent treatment layer or the like on the surface of the sensing unit 70, 200, 210 or the electrode unit 112 by coating or the like.

=== Configuration of Liquid Discharge System etc. ===
Next, as an example of the liquid discharge system according to the present invention, a liquid discharge system including an ink jet printer as a liquid discharge device will be described as an example.

  FIG. 24 is an explanatory diagram showing an external configuration of the liquid ejection system. The liquid ejection system 1000 includes a computer main body 1102, a display device 1104, a printer 1106, an input device 1108, and a reading device 1110. In this embodiment, the computer main body 1102 is housed in a mini-tower type housing, but is not limited thereto. The display device 1104 is generally a CRT (Cathode Ray Tube), a plasma display, a liquid crystal display device, or the like, but is not limited thereto. As the printer 1106, the printer described above is used. In this embodiment, the input device 1108 is a keyboard 1108A and a mouse 1108B, but is not limited thereto. In this embodiment, the reading device 1110 uses a flexible disk drive device 1110A and a CD-ROM drive device 1110B. However, the reading device 1110 is not limited to this. For example, an MO (Magnet Optical) disk drive device or a DVD (Digital Versatile) is used. Disk) etc. may be used.

  25 is a block diagram showing a configuration of the liquid ejection system shown in FIG. An internal memory 1202 such as a RAM and an external memory such as a hard disk drive unit 1204 are further provided in a housing in which the computer main body 1102 is housed.

  The computer program for controlling the operation of the printer 1 can be downloaded to a computer 1000 or the like connected to the printer 1106 via a communication line such as the Internet, and recorded on a computer-readable recording medium. It can also be distributed. As the recording medium, for example, various recording media such as a flexible disk FD, a CD-ROM, a DVD-ROM, a magneto-optical disk MO, a hard disk, and a memory can be used. Note that information stored in such a storage medium can be read by various reading devices 1110.

  In the above description, an example in which the printer 1106 is connected to the computer main body 1102, the display device 1104, the input device 1108, and the reading device 1110 to configure the liquid ejection system has been described. However, the present invention is not limited to this. is not. For example, the liquid ejection system may include a computer main body 1102 and a printer 1106, and the liquid ejection system may not include any of the display device 1104, the input device 1108, and the reading device 1110. Further, for example, the printer 1106 may have a part of each function or mechanism of the computer main body 1102, the display device 1104, the input device 1108, and the reading device 1110. As an example, the printer 1106 includes an image processing unit that performs image processing, a display unit that performs various displays, a recording medium attachment / detachment unit for attaching / detaching a recording medium that records image data captured by a digital camera or the like. It is good also as a structure to have.

  The printing system realized in this way is a system superior to the conventional system as a whole system.

=== Other Embodiments ===
While the printing apparatus has been described based on one embodiment, the above embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed or improved without departing from the gist thereof, and needless to say, the present invention includes equivalents thereof. In particular, even the embodiments described below are included in the liquid discharge inspection apparatus, the liquid discharge apparatus, and the liquid discharge system according to the present invention.

  In the present embodiment, part or all of the configuration realized by hardware may be replaced by software, and conversely, part of the configuration realized by software may be replaced by hardware.

  Further, a part of the processing performed on the liquid ejection apparatus (inkjet printer 1) side may be performed on the host computer 140 side, and a dedicated process is performed between the liquid ejection apparatus (inkjet printer 1) and the host computer 140. A part of the processing may be performed by this processing apparatus via an apparatus.

<About liquid>
In the above-described embodiment, the case where ink is used as the liquid has been described as an example. However, the liquid ejection apparatus according to the present invention is not limited to ink, but other liquids such as metal materials, organic Various liquids such as materials (for example, polymer materials), magnetic materials, conductive materials, wiring materials, film forming materials, electronic ink, various processing liquids, and gene solutions may be used instead of ink.

<About the liquid ejection part>
In the above-described embodiment, the nozzle row 211 of the head 21 of the ink jet printer 1 has been described as the liquid discharge portion of the present invention. However, in the liquid discharge portion of the present invention, such a nozzle row 211 is used. The present invention is not limited to this, and any type of discharge unit may be used as long as it discharges liquid.

<About the sensor>
In the above-described embodiment, the sensing unit 70 made of a wire and the sensing unit 200 formed in a coil shape have been described as the sensing unit of the present invention. However, in the sensing unit of the present invention, Not only the sensing units 70 and 200, but other shapes and other types of sensing units may be used.

  In the above-described embodiment, the sensing units 70 and 200 provided on the substrate 72 have been described as the sensing unit of the present invention. However, in the sensing unit of the present invention, such a substrate is not necessarily used. It does not need to be provided on 72, and may be installed in other forms.

<About the detector>
In the above-described embodiment, the detection unit 80 for detecting the current fluctuation of the sensing unit 70 has been described as the detection unit of the present invention. However, in the detection unit of the present invention, such a detection unit 80 includes Not limited to this, if it is possible to detect whether or not an induced current is generated in the sensing units 70 and 200 by the charged liquid (ink) ejected from the liquid ejection unit (the nozzle row 211 of the head 21). Any type of detection unit may be used.

<About the electrode section>
In the above-described embodiment, the electrode portion formed of the wire has been described as the electrode portion of the present invention. However, the electrode portion of the present invention is not limited to such an electrode portion, but a liquid discharge portion. As long as an electric field is formed with respect to (head 21), any form of electrode portion may be used.

<Discharge inspection>
In the above-described embodiment, the ejection inspection is performed for each nozzle. In the ejection inspection according to the present invention, ink is ejected simultaneously from a plurality of nozzles, and the ejection inspection is performed on two or more nozzles simultaneously. You may make it do. In this case, for example, when the ink is normally ejected from two or more nozzles, the magnitudes of the induced currents generated in the sensing units 70 and 200 and the sensing units 70 and 200 when the ejection failure nozzle is included are included. From the difference from the magnitude of the induced current that is generated, it is possible to examine the presence or absence of ejection individually for each nozzle.

<About liquid ejection inspection device>
In the above-described embodiment, the liquid discharge inspection apparatus mounted on the liquid discharge apparatus using the ink jet printer as an example has been described as the liquid discharge inspection apparatus. However, in the liquid discharge inspection apparatus according to the present invention, It is not limited to such a device, and may be a device that can be separated from the liquid ejection device and can independently perform only the liquid ejection inspection, and is mounted on other devices other than the liquid ejection device described above. A liquid discharge inspection apparatus may be used.

<About liquid ejection device>
In the above-described embodiment, the ink jet printer has been described as an example of the liquid discharge inspection apparatus. However, the liquid discharge apparatus according to the present invention is not limited to such an ink jet printer, and is an apparatus that discharges liquid. Any device may be used as long as it is present.

<About media>
As for the media, the above-mentioned paper includes plain paper, matte paper, cut paper, glossy paper, roll paper, paper, photographic paper, roll type photographic paper, etc. In addition to these, films such as OHP film and glossy film It may be a material, a cloth material, a metal plate material, or the like. That is, any medium can be used as long as it can be an ink ejection target.

The perspective view of an inkjet printer. The internal block diagram of an inkjet printer. Sectional drawing which shows the conveyance part of an inkjet printer. The block block diagram which shows the system configuration | structure of an inkjet printer. The top view which shows the nozzle of a head. The circuit diagram which shows one Embodiment of a nozzle drive circuit. 4 is a timing chart of an original signal ODRV, a print signal PRT (i), and a drive signal DRV (i) showing operations of the drive signal generator. 6 is a flowchart for explaining an example of a processing flow of printing processing. Explanatory drawing explaining the liquid discharge test | inspection apparatus of this embodiment. Explanatory drawing explaining the test | inspection principle of the liquid discharge test | inspection apparatus of this embodiment. FIG. 11A is a plan view showing a sensing unit of the present embodiment, and FIG. 11B is a longitudinal sectional view of the sensing unit. Explanatory drawing explaining the installation position of the sensing part of this embodiment. Explanatory drawing explaining the positional relationship of the sensing part and nozzle row of this embodiment. The ink recovery unit of this embodiment will be described. Explanatory drawing which showed the waveform of the drive signal of a nozzle, and the output signal of a detection part. The flowchart explaining one Embodiment of a test | inspection procedure. The flowchart explaining one Embodiment of a test | inspection procedure. 9 is a flowchart for explaining a discharge inspection procedure for each nozzle row. Explanatory drawing explaining other embodiment of the liquid discharge inspection apparatus which concerns on this invention. Explanatory drawing explaining other embodiment of the liquid discharge inspection apparatus which concerns on this invention. FIG. 20A illustrates an example when the electrode unit is disposed on the side of the sensing unit, and FIG. 20B illustrates an example when the electrode unit is disposed above the sensing unit. FIG. 21A is a plan view when the electrode portion is attached to the substrate together with the sensing portion, and FIG. 21B is a longitudinal sectional view when the electrode portion is attached to the substrate together with the sensing portion. FIG. 22A is a plan view of a substrate to which the sensing unit of the present invention is attached, and FIG. 22B is a longitudinal sectional view of the substrate. FIG. 23A is a plan view of a substrate to which the sensing unit of the present invention is attached, and FIG. 23B is a longitudinal sectional view of the substrate. 1 is a perspective view illustrating an embodiment of a liquid ejection system according to the present invention. The block block diagram which shows the structure of the liquid discharge system of FIG.

Explanation of symbols

1 Inkjet printer, 2 operation panel, 3 paper discharge unit, 4 paper supply unit,
5 operation buttons, 6 indicator lamps, 7 paper discharge tray, 8 paper feed tray,
11A paper insertion slot, 11B roll paper insertion slot, 13 paper feed roller, 14 platen,
15 paper transport motor (PF motor), 17A transport roller, 17B paper discharge roller,
18A / 18B free rollers, 21 heads, 211 nozzle rows,
22 Head driver, 30 Cleaning unit, 31 Pump device,
35 capping device, 41 carriage,
42 Carriage motor (CR motor), 44 pulley, 45 timing belt,
46 guide rail, 48 ink cartridge, 51 linear encoder,
60 liquid ejection inspection device, 70 sensing unit, 72 substrate, 74 opening,
76 fixing member, 80 detector, 82 circuit element, 83 circuit element, 84 circuit element,
88 A / D conversion unit, 90 ink recovery unit, 100 liquid ejection inspection device,
110 Liquid discharge inspection device, 112 electrode part, 114 fixing member,
122 buffer memory, 124 image buffer,
126 system controller, 127 main memory,
128 Carriage motor controller, 129 EEPROM, 130 Transport controller,
132 head drive unit, 134 rotary encoder, 136 linear encoder,
140 host computer, 200 sensing unit, 202 substrate, 204 opening,
210 sensing unit, 212 substrate, 214 opening, 211 nozzle row,
220 drive circuit, 221 original drive signal generator, 222 mask circuit,
223 drive signal correction circuit, 1200 display device, 1201 display,
1300 input device, 1300A keyboard, 1300B mouse,
1400 recording / reproducing apparatus, 1400A flexible disk drive apparatus,
1400B CD-ROM drive device, 1000 liquid ejection system,
Ap printing area, An non-printing area, S medium, Ip ink drop,
R1 protection resistance, R2 input resistance, R3 feedback resistance, C capacitor,
Amp operational amplifier

Claims (17)

In a liquid discharge inspection apparatus for performing a liquid discharge inspection in a liquid discharge unit,
A sensing unit provided in a non-contact state with the liquid ejection unit;
When an induced current is generated in the sensing unit due to the charged liquid discharged from the liquid discharge unit, it is determined that there is liquid discharge,
A liquid ejection inspecting apparatus according to claim 1, wherein when the induced current is not generated in the sensing unit, it is determined that no liquid is ejected.   The liquid discharge inspection apparatus according to claim 1, wherein when performing the discharge inspection, a liquid droplet is discharged as the liquid from the liquid discharge unit.   The liquid ejection inspection apparatus according to claim 1, further comprising a detection unit that detects the induced current generated in the sensing unit.   The current level of the induced current detected by the detection unit is compared with a predetermined reference level to determine whether or not the induced current is generated in the sensing unit. Liquid discharge inspection device.   5. The liquid discharge inspection apparatus according to claim 1, wherein a voltage is applied to the sensing unit in order to charge the liquid discharged from the liquid discharge unit.   The liquid discharge inspection apparatus according to claim 1, wherein the liquid discharged from the liquid discharge unit is charged by frictional charging.   The liquid discharge inspection apparatus according to claim 1, further comprising an electrode portion to which a voltage is applied in order to charge the liquid discharged from the liquid discharge portion.   The liquid ejection inspection apparatus according to claim 1, wherein the sensing unit is formed of a wire material.   The liquid ejection inspection apparatus according to claim 1, wherein the sensing unit is formed in a coil shape.   The liquid ejection inspection apparatus according to claim 1, wherein a water repellent treatment is performed on a surface of the sensing unit.   The liquid discharge inspection apparatus according to claim 1, wherein the liquid discharged from the liquid discharge unit is ink. In a liquid discharge inspection apparatus for performing a liquid discharge inspection in a liquid discharge unit,
A sensing unit provided in a non-contact state with the liquid ejection unit;
When an induced current is generated in the sensing unit due to the charged liquid discharged from the liquid discharge unit, it is determined that there is liquid discharge,
If the induced current does not occur in the sensing unit, determine that there is no liquid discharge,
When performing the inspection, a liquid droplet is discharged from the liquid discharge unit as the liquid,
A detection unit for detecting the induced current generated in the sensing unit;
The signal level of the output signal output from the detection unit is compared with a predetermined reference level to determine whether the induced current is generated in the sensing unit,
In order to charge the liquid ejected from the liquid ejection unit, a voltage is applied to the sensing unit,
The sensing part is formed of a wire;
Water repellent treatment is applied to the surface of the sensing unit,
A liquid discharge inspection apparatus, wherein the liquid discharged from the liquid discharge unit is ink. A method for performing a liquid discharge inspection in a liquid discharge unit,
When an induced current is generated by the charged liquid discharged from the liquid discharge unit to the sensing unit provided in a non-contact state with the liquid discharge unit, it is determined that there is liquid discharge,
A liquid discharge inspection method, wherein when no induced current is generated in the sensing unit, it is determined that no liquid is discharged. In a liquid ejection apparatus provided with a liquid ejection unit that ejects liquid to a medium,
A sensing unit provided in a non-contact state with the liquid ejection unit;
When an induced current is generated in the sensing unit due to the charged liquid discharged from the liquid discharge unit, it is determined that there is liquid discharge,
A liquid ejection apparatus comprising: a liquid ejection determination unit that determines that no liquid is ejected when the induced current is not generated in the sensing unit. In an inkjet printer having an ink ejection unit that ejects ink onto a medium,
A sensing unit provided in a non-contact state with the ink ejection unit;
When an induced current is generated in the sensing unit due to the charged ink ejected from the ink ejection unit, it is determined that there is ink ejection,
An ink jet printer, comprising: an ink ejection determination unit that determines that no ink is ejected when the induced current is not generated in the sensing unit. A program executed in a liquid discharge inspection apparatus that performs liquid discharge inspection in a liquid discharge unit,
Discharging the charged liquid from the liquid discharge unit;
When an induced current is generated by the charged liquid discharged from the liquid discharge unit to the sensing unit provided in a non-contact state with the liquid discharge unit, it is determined that there is liquid discharge,
And a step of determining that no liquid is ejected when the induced current is not generated in the sensing unit. In a liquid ejection system comprising a computer main body and a liquid ejection device connectable to the computer main body,
The liquid ejection device includes a liquid ejection unit that ejects liquid onto a medium;
A sensing unit provided in a non-contact state with the liquid ejection unit;
When an induced current is generated in the sensing unit due to the charged liquid discharged from the liquid discharge unit, it is determined that there is liquid discharge,
A liquid ejection system comprising: a liquid ejection determination unit that determines that no liquid is ejected when no induced current is generated in the sensing unit.

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