JP4670304B2 - Liquid droplet ejection inspection device, liquid droplet ejection device, liquid droplet ejection system, and method for inspecting ejection state of liquid droplet ejection unit - Google Patents

Description

  The present invention relates to a liquid droplet ejection inspection device, a liquid droplet ejection device, a liquid droplet ejection system, and a method for inspecting the ejection state of a liquid droplet ejection unit that perform a liquid droplet ejection test from a liquid droplet ejection unit.

As a liquid droplet ejecting apparatus, an ink jet printer that performs printing by ejecting ink onto various media such as paper, cloth, and film is known. This inkjet printer prints an image by ejecting ink droplets of each color such as cyan (C), magenta (M), yellow (Y), black (K), etc. from nozzles to form dots on a medium. is there.
However, in such an ink jet printer, the nozzles may be clogged due to ink sticking or the like, and ink droplets may not be ejected normally. In that case, dots cannot be formed properly on the medium, and it becomes impossible to perform beautiful printing.
Therefore, various methods for inspecting whether ink droplets are normally ejected have been proposed.

As an example, there is a method in which a charged ink droplet is ejected from a nozzle toward a detection plate, and a change in current when the charged ink droplet collides with the detection plate is detected to inspect the ejection state of the ink droplet. (See Patent Document 1).
JP-A-11-170569

As another method, there is a method proposed by the applicant of the present application in a patent-pending specification. In this method, charged ink droplets are ejected from the nozzles toward the ink droplet receiving portion, and when the ink droplets pass through the side of the conductor portion disposed between them, induction that occurs in the conductor portion is generated. This is a method for inspecting the ejection state of ink droplets based on whether or not current is detected.
In the former method, as one of the measures for increasing the inspection accuracy, the number of ink droplets ejected is increased in order to increase the current change amount of the detection plate.
However, in the latter method, even if the number of ejections is simply increased, the inspection accuracy cannot be improved as expected and the inspection time is unnecessarily extended or only ink drops are wasted. There is.

  The present invention has been made in view of such circumstances, and an object of the present invention is to detect an induced current generated in a conductor portion disposed between a liquid droplet discharge portion and a liquid droplet receiving portion, and thereby detect a liquid. Liquid droplet ejection inspection device that inspects the ejection state of liquid droplets from the droplet ejection unit, and can reliably prevent the ejection of useless liquid droplets that cannot contribute to the improvement of inspection accuracy The purpose is to provide.

The main invention for achieving the object is as follows:
(A) a liquid drop receiving part for receiving a liquid drop discharged from the liquid drop discharge part;
(B) a conductor portion that is disposed between the liquid droplet discharge portion and the liquid droplet receiving portion, and an induced current is generated by passage of the charged liquid droplet;
(C) a detection unit for detecting an induced current of the conductor unit;
(D) A controller that generates a signal for ejecting the liquid droplets, and in order to inspect the ejection state of the liquid droplets from the liquid droplet ejecting unit, a plurality of liquid droplets are continuously connected to the liquid droplet ejecting unit. When discharging from
A controller that generates the signal so that a total length of the liquid droplet group composed of the plurality of liquid droplets is shorter than a distance between the liquid droplet discharge unit and the liquid droplet receiving unit;
And (E) a liquid drop ejection inspection device.
Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

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

(A) a liquid drop receiving part for receiving a liquid drop discharged from the liquid drop discharge part;
(B) a conductor portion that is disposed between the liquid droplet discharge portion and the liquid droplet receiving portion, and an induced current is generated by passage of the charged liquid droplet;
(C) a detection unit for detecting an induced current of the conductor unit;
(D) A controller that generates a signal for ejecting the liquid droplets, and in order to inspect the ejection state of the liquid droplets from the liquid droplet ejecting unit, a plurality of liquid droplets are continuously connected to the liquid droplet ejecting unit. When discharging from
A controller that generates the signal so that a total length of the liquid droplet group composed of the plurality of liquid droplets is shorter than a distance between the liquid droplet discharge unit and the liquid droplet receiving unit;
A liquid droplet ejection inspection apparatus comprising (E).
According to such a liquid droplet ejection inspection apparatus, the plurality of liquid droplets are ejected such that the total length of the liquid droplet group is shorter than the distance between the liquid droplet ejection portion and the liquid droplet receiving portion. Therefore, it is possible to effectively prevent the ejection of liquid droplets that do not contribute to increasing the induced current of the conductor portion, and it is possible to reliably prevent the ejection of useless liquid droplets that cannot contribute to the improvement of inspection accuracy. Become.

In such a liquid droplet ejection inspection apparatus,
The total length of the liquid droplet group is set so as to be the longest length among the lengths in which an induced current is always generated by the liquid droplet group.
In such a liquid droplet ejection inspection apparatus,
The liquid droplet ejection inspection apparatus, wherein the liquid droplet ejection unit and the liquid droplet receiver are electrically grounded.
According to such a liquid droplet ejection inspection apparatus, it is possible to more reliably prevent the ejection of useless liquid droplets that cannot contribute to the improvement of inspection accuracy.
According to such a liquid droplet ejection inspection apparatus, the magnitude of the induced current can be maximized while effectively preventing ejection of a liquid droplet that does not contribute to increasing the induced current.

In such a liquid droplet ejection inspection apparatus,
The liquid droplet ejection apparatus according to claim 1, wherein 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 conductor unit.
According to such a liquid droplet ejection apparatus, it is possible to easily inspect whether or not a liquid droplet has been ejected from the liquid droplet ejection unit, using the induced current detected by the detection unit.

In such a liquid droplet ejection inspection apparatus,
A liquid drop discharge inspection apparatus, wherein a voltage is applied to the conductor portion in order to charge the liquid drop discharged from the liquid drop discharge portion.
According to such a liquid droplet ejection inspection apparatus, it is possible to easily charge a liquid droplet ejected from the liquid droplet ejection section.

In such a liquid droplet ejection inspection apparatus,
The liquid droplet discharge inspection apparatus, wherein the conductor portion is disposed at a position closer to the liquid droplet discharge portion than the liquid droplet receiving portion.
According to such a liquid droplet ejection inspection apparatus, since the electric field generated between the liquid droplet ejection portion and the conductor portion can be strengthened, before the liquid droplet passes through the side of the conductor portion, The liquid droplet can be reliably charged.

In such a liquid droplet ejection inspection apparatus,
The liquid droplet discharge inspection apparatus, wherein the conductor portion is formed of a wire.
According to such a liquid droplet ejection inspection apparatus, it is possible to easily detect whether or not a liquid droplet is ejected from the liquid droplet ejection section with a very simple configuration.

In such a liquid droplet ejection inspection apparatus,
The liquid droplet ejection inspection apparatus, wherein the liquid droplet ejected from the liquid droplet ejection section is an ink droplet.
According to such a liquid droplet ejection inspection device, it is possible to easily perform ejection inspection of a liquid droplet ejection unit that ejects ink droplets.

Further, (A) a liquid drop receiving part for receiving a liquid drop discharged from the liquid drop discharge part,
(B) a conductor portion that is disposed between the liquid droplet discharge portion and the liquid droplet receiving portion, and an induced current is generated by passage of the charged liquid droplet;
(C) a detection unit for detecting an induced current of the conductor unit;
(D) A controller that generates a signal for ejecting the liquid droplets, and in order to inspect the ejection state of the liquid droplets from the liquid droplet ejecting unit, a plurality of liquid droplets are continuously connected to the liquid droplet ejecting unit. When discharging from
A controller that generates the signal so that a total length of the liquid droplet group composed of the plurality of liquid droplets is shorter than a distance between the liquid droplet discharge unit and the liquid droplet receiving unit;
(E)
The liquid droplet discharge unit and the liquid droplet receiver are electrically grounded,
The total length of the liquid droplet group is set to be the longest length among the lengths in which an induced current is always generated by the liquid droplet group,
Comparing the current level of the induced current detected by the detection unit with a predetermined reference level to determine whether the induced current is generated in the conductor unit;
In order to charge the liquid droplets discharged from the liquid droplet discharge portion, a voltage is applied to the conductor portion,
The conductor portion is disposed at a position closer to the liquid droplet discharge portion than the liquid droplet receiving portion,
The conductor portion is formed of a wire,
The liquid droplet ejection inspection apparatus, wherein the liquid droplet ejected from the liquid droplet ejection section is an ink droplet.
According to such a liquid drop ejection inspection device, the effects of the present invention are most effectively achieved because the above-described almost all effects can be achieved.

Further, (A) a liquid droplet ejection unit that ejects liquid droplets onto the medium;
(B) a liquid drop receiving unit that is disposed at a position where there is no medium and receives a liquid drop discharged from the liquid drop discharge unit;
(C) a conductor portion that is disposed between the liquid droplet discharge portion and the liquid droplet receiving portion, and an induced current is generated by passage of the charged liquid droplet;
(D) a detection unit that detects an induced current of the conductor unit;
(E) A controller that generates a signal for ejecting the liquid droplets, and in order to inspect the ejection state of the liquid droplets from the liquid droplet ejecting unit, a plurality of liquid droplets are continuously connected to the liquid droplet ejecting unit. When discharging from
A controller that generates the signal so that a total length of the liquid droplet group composed of the plurality of liquid droplets is shorter than a distance between the liquid droplet discharge unit and the liquid droplet receiving unit;
It is also possible to realize a liquid droplet discharge device including (F).

Further, in a liquid droplet ejection system comprising a computer main body and a liquid droplet ejection device connectable to the computer main body,
The liquid droplet ejection device comprises:
(A) a liquid droplet ejection unit that ejects liquid droplets onto a medium;
(B) a liquid drop receiving unit that is disposed at a position where there is no medium and receives a liquid drop discharged from the liquid drop discharge unit;
(C) a conductor portion that is disposed between the liquid droplet discharge portion and the liquid droplet receiving portion, and an induced current is generated by passage of the charged liquid droplet;
(D) a detection unit that detects an induced current of the conductor unit;
(E) A controller that generates a signal for ejecting the liquid droplets, and in order to inspect the ejection state of the liquid droplets from the liquid droplet ejecting unit, a plurality of liquid droplets are continuously connected to the liquid droplet ejecting unit. When discharging from
A controller that generates the signal so that a total length of the liquid droplet group composed of the plurality of liquid droplets is shorter than a distance between the liquid droplet discharge unit and the liquid droplet receiving unit;
A liquid droplet ejection system including (F) can also be realized.

Further, a liquid drop receiving part for receiving a liquid drop discharged from the liquid drop discharge part,
A conductor portion disposed between the liquid droplet discharge portion and the liquid droplet receiving portion, and an induced current is generated by passage of the charged liquid droplet;
A detection unit that detects an induced current of the conductor unit, and a method for inspecting a discharge state of a liquid droplet discharge unit performed using a liquid droplet discharge inspection apparatus,
In order to inspect the discharge state of the liquid droplets from the liquid droplet discharge unit, when a plurality of liquid droplets are continuously discharged from the liquid droplet discharge unit,
It is also possible to realize a method for inspecting the ejection state of the liquid droplet ejection unit so that the total length of the liquid droplet group composed of the plurality of liquid droplets is shorter than the distance between the liquid droplet ejection unit and the liquid droplet receiving unit. is there.

=== Overview of Liquid Droplet Discharge Device ===
Hereinafter, an embodiment of a liquid droplet ejection apparatus according to the present invention will be described using an inkjet printer 1 as an example.

<Liquid droplet ejection device>
1 to 4 are explanatory diagrams of 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 a transport unit of the ink jet 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 (hereinafter referred to as a carriage movement direction). 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 carriage movement 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 carriage movement direction by the rotation of the carriage motor 42. Move to. The guide rail 46 guides the carriage 41 along the carriage movement direction. In addition, around the carriage 41, a linear encoder 51 for detecting the position of the carriage 41, a transport roller 17A for transporting the medium S along a direction orthogonal to the carriage movement direction, and the transport roller 17A And a paper feed motor 15 that rotationally drives the motor.

  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 droplets Ip onto the medium S in this embodiment. For this purpose, the head 21 is provided with a number of nozzles n for ejecting ink droplets Ip. The ejection mechanism of the ink droplet Ip of the head 21 will be described in detail later.

  In addition, a cleaning unit 30 for eliminating clogging of the nozzles n of the head 21 is provided in 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 nozzle n in order to eliminate clogging of the nozzle n of the head 21 and is operated by a pump motor (not shown). On the other hand, the capping device 35 seals the nozzles n of the head 21 when printing is not performed (for example, during standby) in order to prevent clogging of the nozzles n 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 n 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 21>
FIG. 5 is a view showing the arrangement of the nozzles n provided on the lower surface portion of the head 21. As shown in the figure, a plurality of nozzles n (# 1) to n (# 1) are provided on the lower surface of the head 21 for each of yellow (Y), magenta (M), cyan (C), and black (K) colors. Nozzle row 211 consisting of # 180) is provided. The yellow (Y), magenta (M), cyan (C), and black (K) nozzles n are examples of the “liquid droplet discharge unit”.

  The nozzles n (# 1) to n (# 180) of each nozzle row 211 are arranged in a straight line along the transport direction of the paper S. The nozzle rows 211 are arranged in parallel with a space therebetween along the carriage movement direction. Each nozzle n is provided with a piezo element (not shown) as a drive element for ejecting the ink droplet Ip.

  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 each nozzle n of each color as an ink droplet Ip.

  FIG. 6 shows a drive circuit 220 for nozzles n (# 1) to n (# 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 commonly used for each nozzle n. This original signal ODRV includes two pulses of a first pulse W1 and a second pulse W2, as shown in the lower part of the figure, within a period of one pixel (within a time during which the carriage 41 crosses the interval of one pixel). Signal. 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 each nozzle n of the head 21. 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. The drive signal DRV is output toward the piezo element of each nozzle n. The piezo element of each nozzle n is driven based on the drive signal DRV from the mask circuit 222 to discharge the ink droplet Ip.

  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, a small ink droplet Ip is ejected from the nozzle n, and a small dot (small dot) is formed on the medium S. 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 Ip are ejected from the nozzle n, and medium-sized dots (medium dots) are formed on the medium S. 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. Thereby, a large size ink droplet Ip is ejected from the nozzle n, and a large size dot (large dot) is formed on the medium S. 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, the ink droplet Ip is not ejected from the nozzle n, and dots are formed on the medium S. Will not be.

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

=== 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 of supplying the medium S to be printed, here the paper S, 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 S by moving the carriage 41 relative to the medium S. Here, first, forward printing is performed in which the ink droplet Ip is ejected from the head 21 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 21 based on the print data to eject ink droplets Ip. The ink droplets Ip ejected from the head 21 reach the paper and are formed as dots.

  After printing is performed in this way, next, a carrying process for carrying the medium S 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, 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 rotates the carriage motor 42 to move the carriage 41 in the reverse direction, and drives the head 21 based on the print data to eject the ink droplets Ip 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 Drop Discharge Inspection Device 60 ===
Next, an embodiment of the liquid droplet ejection inspection apparatus 60 will be described. Here, a case where the liquid droplet ejection inspection device 60 is mounted on the inkjet printer 1 (liquid droplet ejection device) will be described as an example.

<Outline of Liquid Drop Discharge Inspection Device 60>
9, 10A, and 10B are schematic explanatory diagrams of the liquid droplet ejection inspection apparatus 60 mounted on the inkjet printer 1 of the present embodiment and its inspection method. FIG. 9 is an explanatory diagram of the configuration of the liquid droplet ejection inspection apparatus 60, and FIGS. 10A and 10B are explanatory diagrams of the inspection principle of the liquid droplet ejection inspection apparatus 60.

  The liquid droplet ejection inspection device 60 is disposed in a non-print area An described later (see FIG. 13), and the carriage 41 moves from the print area Ap to the non-print area An along the carriage movement direction. Thus, a discharge inspection can be performed.

  As shown in FIG. 9, the liquid droplet ejection device is disposed between the head 21 and the ink droplet receiver 90 for receiving the ink droplet Ip ejected from the nozzle n of the head 21. And a conductor 70 that generates an induced current IC by passing the charged ink droplet Ip, and a detector 80 that is connected to the conductor 70 and detects the induced current IC.

The conductor portion 70 is made of a conductive wire such as metal, and is arranged to be extended in parallel with the head 21. The conductor portion 70 is disposed so as to face both of them with a gap D1 between the nozzles n of the head 21 and a gap D2 with the ink droplet receiver 90. The distance D1 from the head 21 is set to 2 mm, for example, and the distance D2 from the ink droplet receiving portion 90 is set to 3 mm, so that the conductor portion 70 is arranged closer to the nozzle n. Will be described later.
In addition, a power source (not shown) is connected to the conductor portion 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 the induced current IC generated in the conductor unit 70. In this embodiment, the detection unit 80 includes a capacitor C, an input resistor R2, a feedback resistor R3, and an operational amplifier. It is comprised by the detection circuit provided with Amp. The capacitor C plays a role of inputting the current fluctuation as an electric signal to the operational amplifier Amp through the input resistor R2 when the current fluctuation occurs in the conductor part 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 directed to the system controller 126 in an appropriate form such as digital data. Is output.

  Actually, when performing an ejection test, ink droplets Ip are ejected individually from the nozzles n of the head 21 toward the vicinity of the conductor portion 70. 10A and 10B are diagrams illustrating a state in which the ink droplet Ip is ejected from the nozzle n with the head 21 toward the vicinity of the conductor portion 70. Here, for the sake of simplicity, a case where only one ink droplet Ip is discharged from each nozzle n of the head 21 as shown in FIG. 10A will be described as an example. As shown in FIG. 10B, it is desirable to eject a plurality of ink droplets Ip for each nozzle, and the optimum number of ejections for that purpose will be described later.

  When the ink droplet Ip is ejected, a very high voltage such as 100 V (volts) is applied to the conductor portion 70 by a supply voltage from the power source. As a result, an extremely strong electric field is formed between the head 21 electrically grounded by an appropriate ground member and the conductor portion 70. In such a state, when the ink droplet Ip is ejected from the nozzle n, the ejected ink droplet Ip is charged. Here, as already described with reference to FIG. 9, the conductor portion 70 is disposed closer to the head 21 than the ink droplet receiving portion 90. Therefore, the conductor part 70 can efficiently form a strong electric field between the conductor part 70 and the head 21 while effectively preventing discharge through the ink droplet receiving part 90. Incidentally, the ink droplet receiver 90 is also electrically grounded by an appropriate ground member for safety considerations.

  When the charged ink droplet Ip passes through the vicinity of the conductor portion 70, a current IC (hereinafter referred to as an induced current) flows through the conductor portion 70 by being induced by the ink droplet Ip. 11A shows the change with time of the induced current IC. The waveform has a peak and a valley with the ink drop Ip closest to the conductor 70 as a boundary.

  Although the generation mechanism of the induced current IC is not yet known, it can be explained as follows by, for example, the electrostatic induction phenomenon. 11A shows the change over time in the amount of charge collected in the portion 70a (see FIG. 11B) closest to the flight path of the ink droplet Ip in the conductor 70. FIG. When the negatively charged ink droplet Ip approaches the conductor portion 70, as indicated by the arrow in the left diagram of FIG. 11B, the positive charge in the conductor portion 70 is attracted to the portion 70a and gathers due to this negative charge, The amount of charge in the portion 70a increases. When the ink droplet Ip approaches the maximum value and the ink droplet Ip leaves, the collected positive charges are dispersed from the portion 70a as shown by the arrows in the right diagram of FIG. 11B. The amount of charge in the portion 70a becomes small, and as a result, the change in the amount of charge with time has a waveform consisting of only peaks as shown in the upper part of FIG. 11A. On the other hand, since the current is expressed as a differential value with respect to time of the charge amount, the slope of the graph of the change with time of the charge amount shown in the upper part of FIG. 11A represents the induced current IC flowing through the conductor portion 70. Therefore, the waveform of the induced current IC flowing through the conductor portion 70 is a waveform having a peak portion and a valley portion at the time of closest approach, as shown in the lower part of FIG. 11A. However, this is also a hypothesis when it is an electrostatic induction phenomenon, and the possibility of an electromagnetic induction phenomenon or other physical phenomenon is sufficiently considered, but the charged ink droplet Ip passes through the vicinity of the conductor portion 70. In doing so, it has been experimentally confirmed that an induced current IC as shown in the lower part of FIG.

  Thus, when the induced current IC is generated in the conductor part 70, the current input to the detection part 80 fluctuates, and this current fluctuation 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. Thereby, when the induced current IC is generated in the conductor part 70, this is detected by the detection part 80, and the detection signal is converted from an analog signal into digital data or the like through the A / D conversion part 88 (see FIG. 4). And output to the system controller 126.

  The system controller 126 compares, for example, the current level, that is, the magnitude of the induced current IC generated in the conductor unit 70 with the predetermined reference level from the data from the detection unit 80, and whether or not the ink droplet Ip has been ejected. Determine whether. 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 IC 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 nozzle n, the charged ink droplet Ip does not pass through the vicinity of the conductor portion 70, so that no induced current IC is generated in the conductor portion 70. For this reason, in the detection unit 80, nothing is detected for the current fluctuation, and therefore it is possible to easily check whether or not the ink droplet Ip is normally ejected for each nozzle.

 The size of the ink droplet Ip ejected from the nozzle n at the time of ejection inspection is preferably 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 S. Is preferred. This is because if the size of the ink droplet Ip ejected from the nozzle n is large, the ink droplet Ip ejected from the nozzle n is more likely to be charged, and the induced current IC is more reliably generated in the conductor portion 70. 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.

<Conductor part 70>
12A and 12B show the conductor part 70 of the present embodiment. 12A is a plan view of the conductor part 70, and FIG. 12B is a longitudinal sectional view of the conductor part 70.

  The conductor part 70 of this embodiment is provided on the printed wiring board 72 shape | molded in the rectangular shape, as shown to FIG. 12A. The conductor portion 70 is stretched over a substantially rectangular opening 74 formed in the substrate 72 along the length direction, and both end portions thereof are respectively connected to inner edges of the opening 74 via fixing members 76. It is fixed. The ink droplet Ip ejected from each nozzle n of the head 21 passes through the side of the conductor portion 70 (here, the left side of the conductor portion 70), passes through the opening 74 of the substrate 72, and is located below. The ink drops are dropped onto the ink droplet receiver 90.

  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. As a result, the substrate 72 having the conductor portion 70 and the circuit elements 82, 83, and 84 serves as a discharge inspection unit for performing a discharge inspection of each nozzle n of the nozzle row 211 of the head 21.

<Installation Position of Conductor 70>
FIG. 13 illustrates the installation position of the conductor part 70 of this embodiment in detail. As shown in the drawing, the conductor portion 70 of the present embodiment has an area An (hereinafter referred to as an area An) that is out of a printing area Ap where printing is performed by ejecting ink droplets Ip from nozzles n (# 1) to n (# 180). Installed in a non-printing area). In this non-printing area An, a pump device 31 that sucks out ink from these nozzles n is provided as a cleaning device for these nozzles n in order to eliminate clogging of the nozzles n. The non-printing area An is provided with a capping device 35 that covers and caps all the nozzles n 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 to the above, the cleaning unit 30 may be provided with various devices such as a wiping device for wiping off extra ink adhering from the openings of the nozzles n.

  In the present embodiment, the conductor portion 70 is provided in a position near 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 over the conductor portion 70. Thus, the ejection inspection of the ink droplet Ip can be executed at any time during non-printing when the carriage 41 moves to the non-printing area An.

<Positional relationship between conductor 70 and nozzle row 211>
FIG. 14 is an explanatory diagram of a positional relationship between the conductor part 70 and the nozzle row 211 when the ejection inspection is performed. As shown in the figure, the conductor portion 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. Thereby, the conductor part 70 is formed so as 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 connected to the conductor portion 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, the ink droplets Ip are individually ejected from the nozzles n of the nozzle row 211 (here, the nozzle row 211 (M)) toward the side of the conductor portion 70, and the ejection inspection is performed. Done.

  When the discharge inspection is completed for one nozzle row 211 (here, the nozzle row 211 (M)), 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 conductor section 70 is aligned again with the nozzle row 211 (for example, the nozzle row 211 (Y), for example) that performs the next discharge inspection, and the discharge inspection is performed for 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 drop receiver 90>
The ink jet printer 1 according to the present embodiment includes an ink droplet receiving portion 90 for receiving and collecting the ink droplet Ip ejected for ejection inspection. FIG. 15 is an explanatory diagram of the ink droplet receiver 90. As shown in the figure, for example, the ink droplet receiving portion 90 is disposed opposite to the lower side of the substrate 72 provided with the conductor portion 70, and is ejected from each nozzle n of the head 21 and passes through the side of the conductor portion 70. Then, the ink droplet Ip that has dropped through the opening 74 of the substrate 72 is received and received. Thus, by collecting the ink droplet Ip used for the ejection inspection by the ink droplet receiver 90, the inside of the printer 1 can be prevented from being contaminated by the ink droplet Ip.

  In this embodiment, the ink droplet receiving portion 90 is formed as a concave accommodating portion as shown in the figure. However, if the ink droplet Ip used for the ejection inspection is to be collected, for example, a platen 14 or the like may be provided as a groove formed in a concave shape or the like.

<Actual detection waveform>
FIG. 16 shows waveforms of a drive signal output to the nozzle n and an output signal from the detection unit 80 in order to discharge the ink droplet Ip during the discharge inspection. 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 n, a piezo element provided in the nozzle n to be inspected has a drive pulse Wa for discharging an ink droplet Ip once, that is, one droplet as shown in FIG. Is output as a drive signal.

  On the other hand, when the ink droplet Ip is normally ejected from the nozzle n to be inspected by such a drive signal, an induced current is induced in the conductor portion 70 by the ink droplet Ip ejected from the nozzle n to be inspected. An IC is generated, and this induced current IC is detected by the detection unit 80, and a pulse Wb having a shape similar to that of the induced current IC is provided as a detection signal from the detection unit 80, that is, a peak portion and a valley portion are provided. Waveform pulses are output. It should be noted that the detection signal pulse output from the detection unit 80 is a drive signal because an appropriate time is required until the induced current IC is generated after the ink droplet Ip is ejected from the nozzle n to be inspected. It is a little behind compared with the drive pulse.

  On the other hand, when the ink droplet Ip is not normally ejected from the nozzle n, no induced current IC is generated in the conductor portion 70. Therefore, the waveform of the output signal of the detection portion 80 is as shown in FIG. The pulse Wb does not appear clearly.

  The ejection inspection is performed for a plurality of nozzles n, for example, one nozzle row 211, that is, 180 nozzles n of nozzles n (# 1) to n (# 180). For this reason, as shown in the upper part of the figure, the drive signal repeatedly outputs a drive pulse for discharging only one ink droplet Ip to be inspected at a predetermined period T. Further, the output signal of the detection unit 80 corresponds to the drive signal, and if the ink droplet Ip is normally ejected from each nozzle n, the peak portion is output at a predetermined cycle T as shown in the lower part of FIG. And a valley having a trough. 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 n 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 droplet Ip is normally ejected from each nozzle n.

<Inspection procedure>
Next, the inspection procedure will be described. FIG. 17 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 conductor part 70 corresponds only to the nozzle row 211 for one row, each nozzle row 211 (K), 211 (C), 211 (M), 211 (Y) The carriage 41 (head 21) is moved for each of the nozzles, and the ejection test is performed individually for each of the nozzle rows 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 discharge inspection is completed, it is checked whether or not there is a non-discharge nozzle n in the black (K) nozzle row 211 (K) (S204). Here, if there is even one nozzle n without ejection, it is checked whether or not the number of cleanings has reached a specified number (S220). Here, the specified number is a number considered that recovery of discharge cannot be expected 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 simultaneously with the other nozzle rows 211. . 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 the number of cleanings has reached the specified number in step S220, error processing is performed (S226), and the inspection ends. Here, the error processing may notify the user that there is a nozzle n that is not ejected, for example, and prompt the user to take more effective ejection recovery means. Further, it may be urged to replace the head 21 including the nozzle n that does not discharge. Further, the nozzle n without ejection may be stored, and the printing may be continued by complementing with another nozzle n without using the nozzle n.

  On the other hand, if all of the nozzles n (# 1) to n (# 180) in the black (K) nozzle row 211 (K) are determined to be ejected, the process proceeds to step S206. Thereafter, the same discharge inspection is sequentially performed on the cyan (C) nozzle row 211 (C), the magenta (M) nozzle row 211 (C), and the yellow nozzle row 211 (Y). A series of processing is completed.

  FIG. 18 is a flowchart illustrating a procedure of ejection inspection for each nozzle row 211 (K), 211 (C), 211 (M), and 211 (Y). First, the head 21 is moved toward the conductor part 70 (S302). Then, alignment between the nozzle row 211 to be inspected and the conductor portion 70 is performed (S304). Next, an initial value “1” is set to the variable “k” (S306), and an operation of ejecting only one ink droplet Ip from the “k” -th nozzle n (#k) toward the conductor portion 70 is performed. The ejection inspection is performed (S308). After the end of ejection, a value of “k + 1” is set to the variable “k” (S310), and it is checked whether or not the variable “k” exceeds “180” that is the number of nozzles n (S312). Here, when the variable “k” exceeds “180”, it is determined that the discharge inspection has been completed for all the nozzles n, and the process is terminated.

  On the other hand, if the variable “k” does not exceed “180”, it is determined that all nozzles n (# 1) to n (# 180) have not been inspected, and the process returns to step S308. The ink droplet Ip is ejected from the (k + 1) th nozzle n (# k + 1), and the ejection inspection is performed (S308). Thereafter, the value “k + 1” is set again in the variable “k” (S310), and the discharge inspection is sequentially performed for each nozzle n until the variable “k” exceeds “180” which is the number of nozzles n. Executed.

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

<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 movement direction is changed, the carriage 41 moves to the standby position and the ejection inspection of the nozzle n is executed. As a result, it is possible to avoid the occurrence of defects in the print image due to clogging of the nozzles n 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, a discharge inspection is executed when the printer (printing apparatus) is turned on, and the discharge inspection of the nozzle n is executed as one of the processes during the initialization process of the printer 1. By executing the ejection inspection at such timing, the printing process can be executed smoothly without clogging the nozzles n.

(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 droplet Ip is normally ejected when a printing process is to be performed on one medium S, and each time the medium S is fed, an ejection inspection is performed. Alternatively, 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, it receives print data from the host computer 140 and checks whether or not the ink droplet Ip is normally ejected when printing is to be executed. By performing the ejection inspection at such timing, the printing process can be smoothly executed without clogging of the nozzles n.

  The ejection inspection is not necessarily performed at the timings (1) to (4) described above, and the ejection inspection may be performed at timings other than (1) to (4).

=== About the number of ejections of the ink droplets Ip for each nozzle of the liquid droplet ejection inspection apparatus 60 ===
In the above description, in order to facilitate understanding, the case where only one ink droplet Ip is ejected for each nozzle n has been described as an example. However, the inspection accuracy of the liquid droplet ejection inspection device 60 is improved. From the viewpoint, as shown in FIG. 10B, it is desirable that a plurality of ink droplets Ip be continuously ejected at a predetermined cycle for each nozzle. However, it is not necessary to increase the number of discharges to the dark clouds, but there is an upper limit value of the number of discharges that contributes to the improvement of inspection accuracy. Even if ejection exceeds this upper limit value, the inspection time is unnecessarily extended or the ink droplet Ip is wasted, which is not preferable.

  Hereinafter, the upper limit value of the discharge number will be described in detail. The adjustment of the ejection number of the ink droplets Ip is achieved by the system controller 126 controlling the head driving unit 132, and these correspond to the “controller”.

 As described above, in the ejection inspection of this embodiment, it is determined whether or not the ink droplet Ip is normally ejected from the nozzle n. The magnitude of the induced current IC generated in the conductor portion 70 exceeds a predetermined reference level. It is based on whether or not. Accordingly, in order to increase the inspection accuracy, the size of the induced current IC may be increased, and as one method for increasing the induced current IC, it is conceivable to increase the number of ejections.

  FIGS. 19A to 19C show how the time-dependent change of the induced current IC flowing in the conductor portion 70 changes depending on the difference in the number of ejected ink droplets Ip ejected continuously at a predetermined period. FIG. 19A shows a case where the total number TL of a group of these ink droplets Ip (hereinafter referred to as “ink droplet group”) is made shorter than the distance D3 between the nozzle n and the ink droplet receiver 90 by reducing the number of ejections. FIG. 19B shows a case in which the number of ejections is increased so that the total length TL is the same as the distance between the nozzle n and the ink droplet receiver 90. FIG. 19C is a diagram in which the number of ejections is further increased to increase the total length TL. Is a case where the distance is longer than the distance D3 between the nozzle n and the ink droplet receiving portion 90. In all these cases, the size and the ejection cycle of the ink droplet Ip are all set to the same condition, and only the number of ejections is varied. 19A to 19C show a state where the ink droplet Ip is ejected. In FIG. 19C, the ink droplet receiving unit 90 receives the ink droplet group 90 to indicate the total length TL of the ink droplet group. The ink droplets Ip that have been displayed are also displayed in a series of white dots.

 First, the following can be said from the comparison between FIGS. 19A and 19B. When the total length TL of the ink droplet group is shorter than the distance D3 between the nozzle n and the ink droplet receiving portion 90, the magnitude of the induced current IC increases as the total length TL increases. That is, as the number of ejections increases, the maximum value ICm of the induced current IC also increases.

 On the other hand, the following can be said from the comparison between FIGS. 19B and 19C. When the total length TL is longer than the distance D3 between the nozzle n and the ink droplet receiver 90, the maximum value ICm of the induced current IC does not increase even if the total length TL is further increased. The time zone Δt in which the current IC is zero only appears with a width.

 The reason for this is not clarified in the same manner as the generation mechanism of the induction current IC described above. However, if the induction current IC is generated by the electrostatic induction phenomenon, the following assumption is made. It can also be explained.

 For example, as the number of negatively charged ink droplets Ip is increased, the amount of positive charges collected at the portion 70a (the portion closest to the flight path of the ink droplet Ip) in the conductor portion 70 due to electrostatic induction due to these negative charges also increases. Increase. That is, in the upper part of FIG. 20A, a change with time of the amount of charge Qs collected in the portion 70a by a group of ink droplets that are a plurality of ink droplets Ip ejected in succession is shown. This is caused by each ink droplet Ip. It is considered that the change over time of the charge amount Qo can be obtained by superimposing. Since the differential value of the charge amount Qs collected by the ink droplet group with respect to the time is the induced current IC, as shown in the lower part of the figure, the induced current ICs by the ink droplet group is the induced current by each ink droplet Ip. From the above, it can be considered that the maximum value ICm of the induced current IC increases as the number of ejections increases.

 However, the nozzle n of the head 21 and the ink droplet receiver 90 are electrically grounded as shown in FIG. 19A. For this reason, the ink droplet Ip once received by the ink droplet receiving portion 90 no longer loses its electric charge and does not contribute to the electrostatic induction phenomenon at all. That is, the ink droplet Ip that can contribute to collecting positive charges on the portion 70 a of the conductor portion 70 is only the ink droplet flying between the nozzle n and the ink droplet receiving portion 90. Therefore, even if the ink droplet Ip is ejected such that the total length TL of the ink droplet group is longer than the distance D3 between the nozzle n and the ink droplet receiving portion 90, the total amount of the negatively charged ink droplet Ip is the nozzle n And the total amount of ink droplets Ip flying between the ink droplet receiving portion 90 and the ink droplet receiving portion 90 does not increase.

 As a result, even if the ink droplet Ip is ejected so that the total length TL of the ink droplet group is longer than the distance D3, the total amount of positive charges collected in the portion 70a of the conductor portion 70 is as shown in the upper part of FIG. 20B. The maximum value Qm of the total amount is not increased as compared with the case where the total length TL is equal to the distance D3, and only the time period Δt in which the saturated state is maintained appears. Become. The time-dependent change of the induced current IC, which is the differential value of the charge amount, is as shown in the lower part of FIG. 20B, that is, the time zone Δt in which the induced current IC is zero corresponding to the saturated time zone Δt. The maximum value ICm of the induced current IC does not increase compared to the case where the total length TL is equal to the distance between the nozzle n and the ink droplet receiver 90.

 From this, it can be seen that the upper limit of the number of ejections that contributes to the improvement of inspection accuracy is the number of ejections such that the total length TL of the ink droplet group matches the distance D3 between the nozzle n and the ink droplet receiving part 90. . If the number of ejections is less than the upper limit value, it is possible to reliably prevent the ejection of useless ink droplets Ip that cannot contribute to the improvement of inspection accuracy.

 The upper limit value described above is that the ink drop Ip detectable range R by the conductor part 70 (the position of the ink drop Ip at which the induced current IC is generated in the conductor part 70 by the ink drop Ip) is This is true when the range includes the nozzle n and the ink droplet receiving portion 90. Conversely, as shown in FIG. 21, when the detectable range R of the conductor portion 70 is narrow, Based on the detectable range R, the upper limit value of the number of discharges is determined. Even if the number of ejections is increased more than this, the above-described time zone Δt in which the induced current IC is zero appears only with a width, and the magnitude ICm of the induced current IC does not increase.

 For example, as shown in FIG. 21, when the detectable range R of the conductor part 70 is in the range of 1 mm above and below the conductor part 70, the number of ejections is such that the total length of the ink droplet group is 2 mm (= 1 mm + 1 mm). This is the upper limit. Then, as shown in FIG. 22, even when the total length TL is made longer than this and an ink droplet group of, eg, 4 mm is ejected, a time zone Δt in which the induced current IC is zero appears as shown in FIG. 22A. However, the maximum value ICm of the induced current IC is not different from the case where the total length shown in FIG. 22B is 2 mm, and thus the inspection accuracy cannot be improved.

 In some cases, the detectable range R of the conductor portion 70 may be unknown, but in that case, the upper limit value may be obtained by the following experimental method. First, the temporal change pattern of the induced current IC is measured corresponding to each full length TL while changing the full length TL of the ink droplet group. Next, out of the measured time-varying patterns, a pattern in which the total length TL of the ink droplet group is the longest among the patterns in which the induced current IC due to the ink droplet group is constantly generated is searched for. The number of discharges corresponding to the total length TL is set as the upper limit value. Here, “the induced current IC due to the ink droplet group is always generated” means that the time zone Δt where the induced current IC is zero appears with a width on the pattern as shown in FIG. 22B. That is not.

=== Other Configuration Examples of Inspection Apparatus ===
<Part 1: Use of triboelectric charging>
FIG. 23 illustrates another configuration example of the liquid droplet ejection inspection apparatus. As shown in the figure, the inspection apparatus 100 applies a high voltage to the conductor portion 70 where the induced current IC is generated, like the liquid droplet ejection inspection apparatus 60 described above (see FIGS. 9 and 10A). Thus, the ink droplets Ip ejected from the nozzles n are not charged, but the ink droplets Ip ejected from the nozzles n are naturally charged when they leave the nozzles n. Utilizing this, the ink droplet Ip is charged. For this reason, a configuration in which a high voltage is applied to the conductor portion 70 in order to charge the ink droplet Ip is omitted, and an earth member for electrically grounding the head 21 is also omitted.

In this way, the configuration of the liquid droplet ejection inspection apparatus 100 can be further simplified by charging the ink droplet Ip ejected from each nozzle n using frictional charging.
In the liquid droplet ejection inspection apparatus 100, since a high voltage is not applied to the conductor part 70, the liquid droplet ejection inspection apparatus 100 is provided in the detection unit 80 of the liquid droplet ejection inspection apparatus 60 (see FIGS. 9 and 10A) described above. Capacitor C is omitted from the configuration.

<No. 2; installation of electrode part 112>
FIG. 24 illustrates another configuration example of the liquid droplet ejection inspection apparatus. As shown in the figure, the inspection apparatus 110 includes an electrode part 112 for charging the ink droplet Ip ejected from the nozzle n, separately from the conductor part 70. As shown in the figure, the electrode portion 112 is made of a conductive wire such as metal and is stretched in parallel with the head 21, as with the conductor portion 70. 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.
By providing such an electrode portion 112, an electric field is formed between the head 21 and the electrode portion 112, so that the ink droplet Ip can be charged when it leaves the nozzle n.

  Next, the installation position of the electrode part 112 will be described. 25A and 25B show the installation positions of the electrode portions 112, respectively. FIG. 25A illustrates an example when the electrode part 112 is disposed on the side of the conductor part 70, and FIG. 25B illustrates an example when the electrode part 112 is disposed above the conductor part 70. It is.

  When the electrode part 112 is disposed on the side of the conductor part 70, the electrode part 112 is disposed in parallel with the conductor part 70 with a space between the electrode part 112 as shown in FIG. . The ink droplet Ip ejected from the nozzle n falls downward between the electrode portion 112 and the conductor portion 70. If the electrode part 112 is arranged in this way, the electrode part 112 can be mounted on the substrate 72 similarly to the conductor part 70.

  FIG. 26A is a plan view when the electrode portion 112 is mounted on the substrate 72 together with the conductor portion 70. FIG. 26B is a longitudinal sectional view when the electrode portion 112 is attached to the substrate 72 together with the conductor portion 70. As shown in these drawings, the electrode part 112 is installed in parallel with the conductor 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 portion 112 is disposed above the conductor portion 70, similarly, as shown in FIG. 25B, the electrode portion 112 is spaced in parallel to the conductor portion 70 and parallel to the conductor portion 70. Be placed. However, in this case, the ink droplet Ip passes through the side of the electrode part 112 and the conductor part 70. As described above, the electrode portion 112 is installed above the conductor portion 70, whereby the electrode portion 112 can be brought closer to the head 21, and thereby, the electric field formed between the head 21 and the electrode portion 112 can be reduced. The ink droplet Ip ejected from the nozzle n 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 conductor portion 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 can be made easier to sense by the conductor portion 70.

=== Other Embodiments of Conductor Portion ===
27A and 27B are explanatory views for explaining another embodiment of the conductor portion. 27A is a plan view of the substrate 202 to which the conductor portion 200 is attached, and FIG. 27B is a longitudinal sectional view of the substrate 202 to which the conductor portion 200 is attached. The conductor portion 200 is formed by forming a wire rod into a coil shape. The conductor portion 200 is arranged on the opening portion 204 formed in a rectangular shape at the front end portion of the substrate 72 so that the opening of the coil is aligned, and one end of the wire rod is insulated. The other end is connected to the detection unit 80 while being fixed to the substrate 202 via a material. Then, the ink droplets Ip discharged from the nozzles n of the head 21 fall downward through the approximate center of the opening of the coil.

Thus, when the conductor part 200 is formed in a coil shape and the ink droplet Ip is dropped at the approximate center of the opening of the coil, the conductor part 200 is compared with the linear conductor part 70 of the liquid droplet ejection inspection apparatus 60 described above. Since a larger induced current IC is generated by an electrostatic induction phenomenon or the like, the ink droplet Ip can be sensed with higher accuracy.
Furthermore, in the conductor part 200, the detection accuracy can be further increased as the number of turns as a coil is increased.

  Furthermore, FIG. 28A and FIG. 28B are explanatory drawings explaining other embodiment of a conductor part. 28A is a plan view of the substrate 212 to which the conductor portion 210 is attached, and FIG. 28B is a longitudinal sectional view of the substrate 212 to which the conductor portion 210 is attached. The conductor portion 210 is formed as a thin layer in a plate shape on the substrate 212. For example, the conductor portion 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 conductor portion 210, a slit-shaped opening 214 for allowing the ink droplet Ip ejected from the nozzle n to pass therethrough is provided.

  The electrode portion 112 is also formed by attaching a metal plate directly on the substrate 212 or the like as the conductor portion 210, or is provided as a thin layer in a plate shape by a film forming technique such as vapor deposition. May be.

<Water repellent treatment>
About the above-mentioned conductor parts 70, 200, and 210, the surface may be subjected to water repellent treatment. As described above, if the surface of the conductor portions 70, 200, and 210 is subjected to water repellent treatment, even when the ink droplet Ip ejected from the nozzle n contacts the conductor portions 70, 200, 210, the conductor portion 70. , 200, 210 can easily remove the ink.
Similarly, the above-described electrode portion 112 may be subjected to water repellent treatment on the surface thereof. As described above, if the surface of the electrode part 112 is also subjected to the water repellent treatment, the ink is removed from the surface of the electrode part 112 even when the ink droplet Ip ejected from the nozzle n adheres to the electrode part 112. Can be made easier.
Examples of the water repellent treatment include well-known methods including a method of providing a water repellent treatment layer on the surface of the conductor portions 70, 200, 210 or the electrode portion 112 by coating or the like.

=== Configuration of Liquid Droplet Discharge System 1000 etc. ===
Next, as an example of the liquid droplet ejection system 1000 according to the present invention, a liquid droplet ejection system 1000 including a printer 1106 as a liquid droplet ejection device will be described as an example.

  FIG. 29 is an explanatory diagram showing an external configuration of the liquid droplet ejection system 1000. The liquid droplet 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 ink jet printer 1 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. Others such as Disk) may be used.

  FIG. 30 is a block diagram showing a configuration of the liquid droplet 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, the 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 droplet ejection system has been described. It is not a thing. For example, the liquid droplet ejection system may include a computer main body 1102 and a printer 1106, and the liquid droplet 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 droplet ejection inspection device, the liquid droplet ejection device, and the liquid droplet ejection 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.
In addition, a part of the processing performed on the liquid droplet ejection apparatus (inkjet printer 1) side may be performed on the host computer 140 side, and only between the liquid droplet ejection apparatus (inkjet printer 1) and the host computer 140. A part of the processing may be performed by this processing apparatus.

<About liquid droplets>
In the above-described embodiment, the case where the ink droplet Ip is used as the liquid droplet has been described as an example. However, the liquid droplet ejection device is not limited to the ink droplet Ip, and other liquid droplets, for example, Various liquid droplets such as a metal material, an organic material (for example, a polymer material), a magnetic material, a conductive material, a wiring material, a film forming material, electronic ink, various processing liquids, and a gene solution may be used instead of the ink.

<About the liquid droplet ejection unit>
In the above-described embodiment, the nozzle n of the head 21 of the ink jet printer 1 has been described as the liquid droplet discharge unit. However, the present invention is not limited to this, and any other device that discharges liquid droplets may be used. It may be a discharge part of a form.

<About conductor part>
In the above-described embodiment, the conductor portion 70 made of a wire rod or the conductor portion 200 formed in a coil shape has been described as the conductor portion. However, the present invention is not limited to this, and other shapes and other types are available. A conductor portion may be used.
In the above-described embodiment, the conductor portions 70 and 200 provided on the substrate 72 have been described as the conductor portions. However, the conductor portions 70 and 200 are not necessarily provided on the substrate 72, and are installed in other forms. May be.

<About the detector>
In the above-described embodiment, the detection unit 80 that detects the current fluctuation of the conductor unit 70 has been described as the detection unit. However, the detection unit 80 is not limited to this, and from the liquid droplet discharge unit (the nozzle n of the head 21). As long as it is possible to detect whether or not the induced current IC is generated in the conductor portions 70 and 200 by the discharged charged liquid droplet (ink droplet Ip), any type of detection portion can be used. It doesn't matter.

<About the electrode section>
In the above-described embodiment, the electrode portion formed of the wire material has been described as the electrode portion. However, the present invention is not limited to this, and any electrode may be used as long as an electric field is formed between the nozzle n and the electrode portion. The electrode portion may be in the form.

<Discharge inspection>
In the above-described embodiment, the ejection inspection is performed for each nozzle n. However, the ink droplets Ip are ejected simultaneously from a plurality of nozzles n, and the ejection inspection is performed for two or more nozzles n at the same time. good. In this case, for example, when the ink droplet Ip is normally ejected from two or more nozzles n, the size of the induced current IC generated in the conductor portions 70 and 200 and the conductor when the ejection failure nozzle n is included. Based on the difference from the magnitude of the induced current IC generated in the sections 70 and 200, the presence or absence of ejection can be individually examined for each nozzle.

<About liquid droplet ejection inspection device>
In the above-described embodiment, the liquid droplet ejection inspection apparatus mounted on the liquid droplet ejection apparatus taking the ink jet printer as an example is described as the liquid droplet ejection inspection apparatus. However, the liquid droplet ejection apparatus is not limited to this. The apparatus may be a device that is capable of performing only the liquid droplet ejection test independently from the above, and is a liquid droplet ejection testing device mounted on another device other than the liquid droplet ejection device described above. May be.

<About liquid droplet ejection device>
In the above-described embodiment, the ink jet printer 1 has been described as an example of the liquid droplet discharge inspection device. However, the present invention is not limited to this, and any device that discharges liquid droplets may be used. It doesn't matter.

<About Medium S>
As for the medium S, 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, OHP film, glossy film, etc. It may be a film material, a cloth material, a metal plate material, or the like. In other words, any medium may be used as long as it can be an ejection target of the ink droplet Ip.

1 is a perspective view of an inkjet printer 1. FIG. 1 is an internal configuration diagram of an inkjet printer 1. FIG. 2 is a cross-sectional view illustrating a transport unit of the inkjet printer 1. FIG. 1 is a block configuration diagram showing a system configuration of an inkjet printer 1. 3 is a plan view showing an arrangement of nozzles n of a head 21. FIG. 3 is a circuit diagram of a drive circuit 220. FIG. 5 is a timing chart of an original signal ODRV, a print signal PRT (i), and a drive signal DRV (i) showing the operation of the original drive signal generator 221. 6 is a flowchart illustrating an example of a processing procedure of a printing operation. It is explanatory drawing of the structure of the liquid drop discharge test | inspection apparatus 60 which concerns on this embodiment. It is explanatory drawing of the test | inspection principle of the liquid drop discharge test | inspection apparatus 60 which concerns on this embodiment. It is explanatory drawing of the test | inspection principle of the liquid drop discharge test | inspection apparatus 60 which concerns on this embodiment. It is a figure which shows the time-dependent change of the induced current IC which flows through the conductor part 70 by the ink droplet Ip. It is a figure which shows the time-dependent change of the induced current IC which flows through the conductor part 70 by the ink droplet Ip. FIG. 12A is a plan view of the conductor portion 70 according to the present embodiment, and FIG. 12B is a vertical cross-sectional view of the conductor portion 70. It is explanatory drawing of the installation position of the conductor part 70 which concerns on this embodiment. It is explanatory drawing of the positional relationship of the conductor part 70 and nozzle row 211 which concern on this embodiment. It is explanatory drawing of the ink droplet receiving part 90 which concerns on this embodiment. FIG. 6 is an explanatory diagram showing a driving signal for a nozzle n and a waveform of an output signal from a detection unit 80. It is a flowchart explaining one Embodiment of a test | inspection procedure. 10 is a flowchart illustrating a discharge inspection procedure for each nozzle row 211. FIG. 6 is a diagram for explaining how a change with time of an induced current IC flowing in a conductor portion 70 changes depending on a difference in the number of ejected ink droplets Ip. It is a figure which shows the time-dependent change of the electric charge amount Q, and the time-dependent change of the induced current IC. It is a figure which shows the time-dependent change of the electric charge amount Q, and the time-dependent change of the induced current IC. It is a figure which shows the detectable range R of the conductor part. It is a figure which shows the time-dependent change of the electric charge amount Q, and the time-dependent change of the induced current IC. It is explanatory drawing of other embodiment of a liquid droplet discharge test | inspection apparatus. It is explanatory drawing of other embodiment of a liquid droplet discharge test | inspection apparatus. FIG. 25A is an explanatory diagram of an example when the electrode portion 112 is disposed on the side of the conductor portion 70, and FIG. 25B is an explanatory diagram of an example when the electrode portion 112 is disposed above the conductor portion 70. . 26A is a plan view when the electrode portion 112 is attached to the substrate 72 together with the conductor portion 70, and FIG. 26B is a longitudinal sectional view when the electrode portion 112 is attached to the substrate 72 together with the conductor portion 70. . FIG. 27A is a plan view of the substrate 202 to which the conductor portion 200 is attached, and FIG. 27B is a longitudinal sectional view of the substrate 202. FIG. 28A is a plan view of the substrate 212 to which the conductor portion 210 is attached, and FIG. 28B is a longitudinal sectional view of the substrate 212. It is a perspective view explaining one Embodiment of the liquid droplet discharge system 1000 which concerns on this invention. 2 is a block configuration diagram showing a configuration of the liquid droplet ejection system 1000. FIG.

Explanation of symbols

1 Inkjet printer, 2 Operation panel, 3 Paper discharge section, 4 Paper feed section,
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 roller,
21 heads, 211 nozzle rows, 22 head drivers,
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 cartridges, 51 linear encoder,
60 Liquid Drop Discharge Inspection Device, 70 Conductor, 72 Substrate, 74 Opening,
76 fixing member,
80 detectors, 82 circuit elements, 83 circuit elements, 84 circuit elements,
88 A / D converter, 90 ink drop receiver,
100 Liquid droplet ejection inspection device,
110 Liquid droplet ejection inspection device, 112 electrode part, 114 fixing member,
122 buffer memory, 124 image buffer,
126 system controller, 127 main memory,
128 Carriage motor control unit, 129 EEPROM,
130 transport control unit, 132 head drive unit,
134 Rotary encoder, 136 Linear encoder,
140 host computer,
200 conductors, 202 substrates, 204 openings,
210 conductors, 212 substrates, 214 openings,
211 nozzle rows,
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 device,
1400B CD-ROM drive device,
1000 liquid droplet 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,
n Nozzle, R detectable range

Claims (12)

(A) a liquid drop receiving part for receiving a liquid drop discharged from the liquid drop discharge part;
(B) a conductor portion that is disposed between the liquid droplet discharge portion and the liquid droplet receiving portion, and an induced current is generated by passage of the charged liquid droplet;
(C) a detection unit for detecting an induced current of the conductor unit;
(D) A controller that generates a signal for ejecting the liquid droplets, and in order to inspect the ejection state of the liquid droplets from the liquid droplet ejecting unit, a plurality of liquid droplets are continuously connected to the liquid droplet ejecting unit. When discharging from
A controller that generates the signal so that a total length of the liquid droplet group composed of the plurality of liquid droplets is shorter than a distance between the liquid droplet discharge unit and the liquid droplet receiving unit;
A liquid droplet ejection inspection apparatus comprising (E). The liquid droplet ejection inspection apparatus according to claim 1,
The liquid droplet ejection inspection apparatus, wherein the liquid droplet ejection unit and the liquid droplet receiver are electrically grounded. In the liquid drop ejection inspection apparatus according to claim 1 or 2,
The total length of the liquid droplet group is set so as to be the longest length among the lengths in which an induced current is always generated by the liquid droplet group. In the liquid drop ejection inspection apparatus according to any one of claims 1 to 3,
The liquid droplet ejection apparatus according to claim 1, wherein 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 conductor unit. In the liquid drop ejection inspection apparatus according to any one of claims 1 to 4,
A liquid drop discharge inspection apparatus, wherein a voltage is applied to the conductor portion in order to charge the liquid drop discharged from the liquid drop discharge portion. In the liquid drop ejection inspection apparatus according to claim 5,
The liquid droplet discharge inspection apparatus, wherein the conductor portion is disposed at a position closer to the liquid droplet discharge portion than the liquid droplet receiving portion. In the liquid drop ejection inspection apparatus according to any one of claims 1 to 6,
The liquid droplet discharge inspection apparatus, wherein the conductor portion is formed of a wire. In the liquid drop ejection inspection apparatus according to any one of claims 1 to 7,
The liquid droplet ejection inspection apparatus, wherein the liquid droplet ejected from the liquid droplet ejection section is an ink droplet. (A) a liquid drop receiving part for receiving a liquid drop discharged from the liquid drop discharge part;
(B) a conductor portion that is disposed between the liquid droplet discharge portion and the liquid droplet receiving portion, and an induced current is generated by passage of the charged liquid droplet;
(C) a detection unit for detecting an induced current of the conductor unit;
(D) A controller that generates a signal for ejecting the liquid droplets, and in order to inspect the ejection state of the liquid droplets from the liquid droplet ejecting unit, a plurality of liquid droplets are continuously connected to the liquid droplet ejecting unit. When discharging from
A controller that generates the signal so that a total length of the liquid droplet group composed of the plurality of liquid droplets is shorter than a distance between the liquid droplet discharge unit and the liquid droplet receiving unit;
(E)
The liquid droplet discharge unit and the liquid droplet receiver are electrically grounded,
The total length of the liquid droplet group is set to be the longest length among the lengths in which an induced current is always generated by the liquid droplet group,
Comparing the current level of the induced current detected by the detection unit with a predetermined reference level to determine whether the induced current is generated in the conductor unit;
In order to charge the liquid droplets discharged from the liquid droplet discharge portion, a voltage is applied to the conductor portion,
The conductor portion is disposed at a position closer to the liquid droplet discharge portion than the liquid droplet receiving portion,
The conductor portion is formed of a wire,
The liquid droplet ejection inspection apparatus, wherein the liquid droplet ejected from the liquid droplet ejection section is an ink droplet. (A) a liquid droplet ejection unit that ejects liquid droplets onto a medium;
(B) a liquid drop receiving unit that is disposed at a position where there is no medium and receives a liquid drop discharged from the liquid drop discharge unit;
(C) a conductor portion that is disposed between the liquid droplet discharge portion and the liquid droplet receiving portion, and an induced current is generated by passage of the charged liquid droplet;
(D) a detection unit that detects an induced current of the conductor unit;
(E) A controller that generates a signal for ejecting the liquid droplets, and in order to inspect the ejection state of the liquid droplets from the liquid droplet ejecting unit, a plurality of liquid droplets are continuously connected to the liquid droplet ejecting unit. When discharging from
A controller that generates the signal so that a total length of the liquid droplet group composed of the plurality of liquid droplets is shorter than a distance between the liquid droplet discharge unit and the liquid droplet receiving unit;
A liquid droplet discharge device comprising (F). In a liquid droplet ejection system comprising a computer main body and a liquid droplet ejection device connectable to the computer main body,
The liquid droplet ejection device comprises:
(A) a liquid droplet ejection unit that ejects liquid droplets onto a medium;
(B) a liquid drop receiving unit that is disposed at a position where there is no medium and receives a liquid drop discharged from the liquid drop discharge unit;
(C) a conductor portion that is disposed between the liquid droplet discharge portion and the liquid droplet receiving portion, and an induced current is generated by passage of the charged liquid droplet;
(D) a detection unit that detects an induced current of the conductor unit;
(E) A controller that generates a signal for ejecting the liquid droplets, and in order to inspect the ejection state of the liquid droplets from the liquid droplet ejecting unit, a plurality of liquid droplets are continuously connected to the liquid droplet ejecting unit. When discharging from
A controller that generates the signal so that a total length of the liquid droplet group composed of the plurality of liquid droplets is shorter than a distance between the liquid droplet discharge unit and the liquid droplet receiving unit;
A liquid droplet ejection system comprising (F). A liquid drop receiving part for receiving liquid drops discharged from the liquid drop discharge part;
A conductor portion disposed between the liquid droplet discharge portion and the liquid droplet receiving portion, and an induced current is generated by passage of the charged liquid droplet;
A detection unit that detects an induced current of the conductor unit, and a method for inspecting a discharge state of a liquid droplet discharge unit performed using a liquid droplet discharge inspection apparatus,
In order to inspect the discharge state of the liquid droplets from the liquid droplet discharge unit, when a plurality of liquid droplets are continuously discharged from the liquid droplet discharge unit,
A method for inspecting a discharge state of a liquid drop discharge unit, characterized in that a total length of a liquid drop group composed of the plurality of liquid drops is shorter than a distance between the liquid drop discharge unit and the liquid drop receiving unit. .

Images