JP5228279B2 - Inkjet printer, nozzle inspection method and program thereof - Google Patents

Description

  The present invention relates to an inkjet printer, a nozzle inspection method, and a program thereof.

Conventionally, as an ink jet printer, an ink droplet ejected from a nozzle of a print head is charged, and the charged ink droplet is ejected to a portion (inspection area) that receives the ink droplet facing the nozzle, which is caused by the ejection of the ink droplet. A device that inspects whether or not an ink droplet is actually ejected from a nozzle by detecting an induced voltage is known (see, for example, Patent Document 1). Further, a light beam is formed in a direction intersecting the ejection direction in which the ink droplet is ejected from the nozzle of the print head, and the ink droplet is ejected from the nozzle by detecting whether the ink droplet ejected from the nozzle blocks the light beam. There is also known an apparatus that inspects whether or not the liquid is actually discharged (see, for example, Patent Document 2).
JP 59-120464 A JP 2005-35309 A

  However, Patent Documents 1 and 2 do not examine in detail the timing of performing an inspection (referred to as nozzle inspection) as to whether or not an ink droplet has actually been ejected from a nozzle.

  The present invention has been made to solve such a problem, and provides an ink jet printer, a nozzle inspection method, and a program thereof capable of executing a nozzle inspection using a printing recording liquid at an appropriate timing. With the goal.

  The present invention adopts the following means in order to achieve the above-mentioned object.

The first inkjet printer of the present invention is
An inkjet printer that performs printing on a print medium using a print head having a plurality of nozzles that discharge a print recording liquid,
Driving means for driving the print head so that the print recording liquid is discharged from each nozzle;
A printable area in which the print medium is disposed;
An inspection area provided at a position where the print medium is not disposed and capable of receiving a print recording liquid discharged from each nozzle;
Detecting means capable of detecting that the printing recording liquid is actually ejected from each nozzle of the print head arranged above the inspection area;
Inspection timing setting means for setting inspection timing based on the print quality level attached to the print data;
While the print head is disposed above the print medium, the drive means is controlled to print on the print medium by ejecting a print recording liquid from a required nozzle based on print data and the print quality level. When the inspection timing is reached, when the drive means is controlled to discharge the print recording liquid from each nozzle in a state where the print head is arranged above the inspection area, the print recording is actually performed from the nozzle. Control means for performing a nozzle inspection depending on whether or not the detection means has detected that liquid has been discharged;
It is equipped with.

In this ink jet printer, the drive unit is controlled so that printing is performed on the print medium by ejecting the print recording liquid from the required nozzles based on the print data and the print quality level with the print head disposed above the print medium. . On the other hand, when the inspection timing is reached, the print recording liquid is actually discharged from the nozzle when the drive means is controlled to discharge the print recording liquid from each nozzle with the print head arranged above the inspection area. A nozzle inspection is performed depending on whether or not the detection means has detected this. Here, the inspection timing is set based on the print quality level. For this reason, the inspection timing of the nozzle inspection using the printing recording liquid can be advanced or delayed according to the print quality level. Therefore, the nozzle inspection can be executed at an appropriate timing.

  Here, the inspection area may be provided independently of the printable area, but a portion of the printable area where no print medium is arranged may be used as the inspection area. The print quality level attached to the print data includes not only the case where the print quality level is directly attached to the print data but also the case where the print quality level is attached indirectly to the print data. As the former, for example, when the computer that created the print data sends the print data to the inkjet printer, the print quality level applied to the print data is sent along with the print data. For example, there is a case where a print quality level set by the ink jet printer is applied to the print data when printing is performed by the ink jet printer.

  In the first inkjet printer of the present invention, the print quality level may be determined according to a print mode or may be determined according to a paper type. The print mode is, for example, an image quality priority mode or a speed priority mode. The image quality priority mode may be a high print quality level and the speed priority mode may be a low print quality level. Further, the paper type refers to, for example, plain paper or photo-dedicated paper, and the photo-dedicated paper may have a high print quality level and the plain paper may have a low print quality level.

  In the first ink jet printer of the present invention, when setting the inspection timing, the inspection timing setting means may set the inspection timing to arrive earlier as the print quality level is higher. By doing so, the higher the print quality level, the higher the frequency of nozzle inspection, so that even if a nozzle malfunctions, it can be dealt with early. Therefore, when the print quality level is high, it is possible to suppress as much as possible the occurrence of a printing error without discharging the print recording liquid from the nozzles. Conversely, the lower the print quality level, the lower the frequency of nozzle inspection, so that it is possible to minimize the lengthening of printing time due to nozzle inspection.

  The first ink jet printer of the present invention includes a transport unit that transports the print medium in a predetermined transport direction so that the print medium is arranged in the printable area, and the printing in a main scanning direction substantially orthogonal to the transport direction. A head moving means for moving the head, wherein the inspection timing setting means has a predetermined number of pass operations to move the print head in the main scanning direction while printing on the print medium. The control means controls the conveying means, the driving means, and the head moving means to perform the pass operation, and counts the number of pass operations, and the number of pass operations. Whether or not the inspection timing has been reached is determined, and when the inspection timing has been reached, the nozzle inspection may be performed. The inspection timing may be defined by, for example, the elapsed time from the end of the nozzle inspection or the number of printed pages, but there is a correlation between the number of print recording liquid ejections from the nozzle and the occurrence of nozzle clogging. Therefore, it is preferable to define the inspection timing based on the number of pass operations during printing, which is closely related to the number of times of printing recording liquid discharged from the nozzles. At this time, the control means may reset the number of pass operations after performing the nozzle inspection. Further, the control means may control the transport means, the driving means, and the head moving means so that the number of pass operations increases as the print quality level becomes higher when printing the same print data.

  In the first ink jet printer of the present invention, the inspection timing setting means sets the time when the number of ejections of the printing recording liquid reaches a predetermined number of times as the inspection timing, and the control means Controlling the drive means to perform printing on the medium and counting the number of ejections of the printing recording liquid ejected by the printing, and determining whether or not the inspection timing has been reached based on the counted number of ejections; When the inspection timing is reached, the nozzle inspection may be performed. Since there is a correlation between the number of print recording liquid ejections from the nozzles and the occurrence of nozzle clogging, it is preferable to define the inspection timing based on the number of print recording liquid ejections from the nozzles. At this time, the control means may reset the number of pass operations after performing the nozzle inspection. The control means may control the driving means so that the number of ejections of the print recording liquid increases as the print quality level increases in printing the same print data.

  In the first ink jet printer of the present invention, the plurality of nozzles are grouped according to color and eject print recording liquids of the grouped color, and the inspection timing setting means includes the print recording liquid The point in time when the number of ejections reaches a predetermined number of times is set as the inspection timing, and the control unit counts by color when counting the number of ejections of the printing recording liquid ejected by the printing, Whether or not the inspection timing has been reached is determined for each color based on the number of ejections performed, and when the inspection timing is reached, the nozzle inspection is performed only for the nozzles that discharge the print recording liquid of the color that has reached the inspection timing. May be performed. Since there is a correlation between the number of print recording liquid ejections from the nozzles and the occurrence of nozzle clogging, it is preferable to define the inspection timing based on the number of print recording liquid ejections from the nozzles. In addition, since nozzle inspection using a printing recording liquid is not performed for nozzles of colors that do not require inspection, wasteful consumption of the printing recording liquid can be suppressed. At this time, the control means may reset the number of times of the printing recording liquid of the color subjected to the nozzle inspection after performing the nozzle inspection.

  The first inkjet printer of the present invention includes a cleaning unit that performs head cleaning by forcibly sucking each nozzle of the print head, and the inspection timing setting unit sets the inspection timing based on the print quality level. In addition to the setting, the inspection timing may be set even after the head cleaning is executed by the cleaning unit. In this way, it can be confirmed that the print recording liquid is actually ejected from the nozzles by performing the head cleaning. Here, the cleaning unit may perform the head cleaning when a predetermined cleaning time is reached or when an operator instructs to perform cleaning. The predetermined cleaning time is, for example, printing that is supplied to the print head when the print recording liquid can be supplied to the print head for the first time after purchasing an inkjet printer, or when a predetermined time has elapsed since the previous head cleaning. For example, the recording liquid cartridge is empty and replaced.

  In the first ink jet printer of the present invention having the cleaning means as described above, the cleaning means forcibly sucks each nozzle of the print head with a preset suction force among multistage suction forces. The inspection timing setting means may be set so that the inspection timing comes earlier as the set suction force is smaller. After performing head cleaning with a small suction force, nozzles may be clogged because fresh printing recording liquid does not spread to the nozzles, so nozzle clogging can be detected early by performing nozzle inspection at an early stage. It is preferable to do so. The suction force to be used among the multi-step suction forces is not particularly limited. For example, the first head cleaning is performed with the minimum suction force, and the second and subsequent head cleanings are sequentially performed. The force may be increased, or the operator may select an arbitrary suction force by manual operation.

The second inkjet printer of the present invention is
An inkjet printer that performs printing on a print medium using a print head having a plurality of nozzles that discharge a print recording liquid,
Driving means for driving the print head so that the print recording liquid is discharged from each nozzle;
A printable area in which the print medium is disposed;
An inspection area provided at a position where the print medium is not disposed and capable of receiving a print recording liquid discharged from each nozzle;
Detecting means capable of detecting that the printing recording liquid is actually ejected from each nozzle of the print head arranged above the inspection area;
An inspection timing storage means for storing a fixed inspection timing not related to the print quality level attached to the print data;
While the print head is disposed above the print medium, the drive means is controlled to print on the print medium by ejecting a print recording liquid from a required nozzle based on print data and the print quality level. When the inspection timing is reached, when the drive means is controlled to discharge the print recording liquid from each nozzle in a state where the print head is arranged above the inspection area, the print recording is actually performed from the nozzle. Control means for performing a nozzle inspection depending on whether or not the detection means has detected that liquid has been discharged;
It is good also as a thing provided.

  In this ink jet printer, the drive unit is controlled so that printing is performed on the print medium by ejecting the print recording liquid from the required nozzles based on the print data and the print quality level with the print head disposed above the print medium. . On the other hand, when the inspection timing is reached, the print recording liquid is actually discharged from the nozzle when the drive means is controlled to discharge the print recording liquid from each nozzle with the print head arranged above the inspection area. A nozzle inspection is performed depending on whether or not the detection means has detected this. Here, the inspection timing is fixed regardless of the print quality level, but the operation of ejecting the print recording liquid and printing on the print medium is performed based on the print quality level, so the higher the print quality level, the more printing from the nozzles. The number of times of ejecting the recording liquid and the number of pass operations increase. That is, even if the inspection timing is fixed, the higher the print quality level, the higher the inspection frequency. Therefore, the nozzle inspection can be executed at an appropriate frequency. In such an ink jet printer, the inspection timing is the number of pass operations in which the print head is moved in the main scanning direction while printing on the print medium, and the control means prints the same print on the print medium. When printing data, the print head may be controlled such that the higher the print quality level, the greater the number of pass operations. Alternatively, the inspection timing is the number of ejections from the nozzles of the print recording liquid, and the control means increases the number of ejections as the print quality level is higher when printing the same print data on the print medium. The print head may be controlled as described above.

  In the first and second ink jet printers of the present invention, the control means determines whether or not the inspection timing has been reached during the printing, and when the inspection timing has been reached, the nozzle inspection. May be executed. Specifically, when the inspection timing is reached in the middle of printing one print medium, the nozzle inspection may be executed regardless of the middle of the printing, and the printing ends. The nozzle inspection may be executed after waiting for this. Here, when a defective nozzle that does not eject the printing recording liquid is found when the nozzle inspection is executed after the printing is completed, it is preferable to perform a process for normalizing the defective nozzle such as head cleaning. On the other hand, if a defective nozzle is found when a nozzle inspection is performed even though printing is in progress, the color may change if processing for normalizing the defective nozzle is performed during printing. Instead, it is preferable to perform a process in which the defective nozzle complements a portion where the printing recording liquid is to be discharged with another normal nozzle.

  In the first and second ink jet printers of the present invention, the control means determines whether or not the inspection timing has been reached after completion of the printing (for example, printing for one printing medium). Alternatively, it may be determined whether or not the inspection timing has been reached when starting the printing (for example, printing for one printing medium). In this way, when a defective nozzle is found when the nozzle inspection is executed, since the printing is not performed, a process for normalizing the defective nozzle such as head cleaning can be performed immediately. Here, waiting for the end of printing may wait for the end of the processing of the print job or may wait for the end of printing for one page.

  In the first and second ink jet printers of the present invention, the control unit may perform the nozzle inspection when a predetermined time has elapsed without being printed. If it is left unprinted, the nozzle outlet will dry and the print recording liquid will solidify, and the print recording liquid will not be ejected or will be difficult to be ejected. It is preferable to find out early. Further, when a non-ejection nozzle is found, it is preferable to perform a process for normalizing a defective nozzle such as head cleaning.

  In the first and second ink jet printers of the present invention, the detection means detects an electrical change caused by electrostatic induction that occurs between the time when the printing recording liquid is ejected from the nozzle and reaches the inspection region. The printing recording liquid may have blocked the light beam in the direction intersecting the ejection direction of the printing recording liquid during the period from the ejection of the printing recording liquid from the nozzle to the inspection area. It may be a means for detecting whether or not. In any case, since the nozzle is inspected using the printing recording liquid, it is highly significant to apply the present invention.

  In this specification, an ink jet printer refers to a printing apparatus that employs an ink jet recording method. An electronic device equipped with such an ink jet printer may be equipped with an ink jet printer as a single unit, or may be mounted in combination with a scanner or a facsimile. Also, as printing media, various papers used when creating documents, resin films used when creating OHP, etc., as well as glass used when creating color filters, printed wiring boards, etc. Or a substrate made of a resin or the like.

The first nozzle inspection method of the present invention includes:
A print head having a plurality of nozzles for discharging a print recording liquid; a driving means for driving the print head to discharge the print recording liquid from each nozzle; a printable area in which the print medium is disposed; and the printing An inspection area that is provided separately from the possible area and can receive the printing recording liquid discharged from each nozzle, and the printing recording liquid is actually discharged from each nozzle of the print head arranged above the inspection area. A nozzle inspection method using a detecting means capable of detecting
(A) setting an inspection timing based on a print quality level included in the print data;
(B) The drive means for performing printing on the print medium by discharging a print recording liquid from a required nozzle based on the print data and the print quality level in a state where the print head is disposed above the print medium. On the other hand, when the inspection timing is reached, when the drive means is controlled to discharge the print recording liquid from each nozzle in a state where the print head is arranged above the inspection area, Performing nozzle inspection depending on whether or not the detection means has detected that the printing recording liquid has actually been ejected; and
Is included.

  In this nozzle inspection method, when the inspection timing is reached, when the drive means is controlled to discharge the print recording liquid from each nozzle in a state where the print head is arranged above the inspection area, printing is actually performed from the nozzle. A nozzle test is performed depending on whether the detection means detects that the recording liquid has been ejected. Here, the inspection timing is set based on the print quality level. For this reason, the inspection timing of the nozzle inspection using the printing recording liquid can be advanced or delayed according to the print quality level. Therefore, the nozzle inspection can be executed at an appropriate timing. In this nozzle inspection method, various aspects of the first ink jet printer described above may be adopted, or steps for realizing the functions of the first ink jet printer described above may be added. Good.

The second nozzle inspection method of the present invention is:
A print head having a plurality of nozzles for discharging a print recording liquid; a driving means for driving the print head to discharge the print recording liquid from each nozzle; a printable area in which the print medium is disposed; and the printing An inspection area that is provided separately from the possible area and can receive the printing recording liquid discharged from each nozzle, and the printing recording liquid is actually discharged from each nozzle of the print head arranged above the inspection area. A nozzle inspection method using a detection means capable of detecting the detection and a test timing storage means for storing a fixed test timing not related to the print quality level attached to the print data,
The drive means is controlled to print on the print medium by ejecting a print recording liquid from a required nozzle based on the print data and the print quality level in a state where the print head is arranged above the print medium. On the other hand, when the inspection timing is reached, when the drive unit is controlled to discharge the print recording liquid from each nozzle in a state where the print head is arranged above the inspection area, the printing is actually performed from the nozzle. The nozzle inspection may be performed based on whether or not the detection unit detects that the recording liquid has been ejected.

  In this nozzle inspection method, when the inspection timing is reached, when the drive means is controlled to discharge the print recording liquid from each nozzle in a state where the print head is arranged above the inspection area, printing is actually performed from the nozzle. A nozzle test is performed depending on whether the detection means detects that the recording liquid has been ejected. Here, the inspection timing is fixed regardless of the print quality level, but the operation of ejecting the print recording liquid and printing on the print medium is performed based on the print quality level, so the higher the print quality level, the more printing from the nozzles. The number of times of ejecting the recording liquid and the number of pass operations increase. That is, even if the inspection timing is fixed, the higher the print quality level, the higher the inspection frequency. Therefore, the nozzle inspection can be executed at an appropriate frequency. In this nozzle inspection method, various aspects of the second ink jet printer described above may be adopted, and steps for realizing the functions of the second ink jet printer described above may be added. Good.

  The program of the present invention is for causing one or more computers to implement each step of any of the nozzle inspection methods described above. This program may be recorded on a computer-readable recording medium (for example, hard disk, ROM, FD, CD, DVD, etc.), or from a computer via a transmission medium (communication network such as the Internet or LAN). It may be distributed to another computer, or may be exchanged in any other form. If this program is executed by a single computer, or if each step is shared and executed by a plurality of computers, each step of the nozzle inspection method described above is executed, so that the same effect as that method can be obtained. .

[First Embodiment]
First, the first embodiment will be described. FIG. 1 is a configuration diagram showing an outline of the configuration of the inkjet printer 20 according to the first embodiment, FIG. 2 is an explanatory diagram of a print head 24, and FIG. 3 is an explanatory diagram of a paper feed mechanism 31. FIG. 4 is a configuration diagram showing an outline of the configuration of the nozzle inspection device 50.

  As shown in FIG. 1, the inkjet printer 20 of the present embodiment includes a printer mechanism 21 including a print head 24 and a carriage 22, and a paper feed mechanism 31 including a paper feed roller 35 driven by a drive motor 33. A cap device 40 formed in the vicinity of the right end of the platen 44, a nozzle inspection device 50 formed in the vicinity of the left end on the platen 44 and inspecting whether ink droplets are normally ejected from the print head 24, and an inkjet printer 20 and a controller 70 for controlling the entire system 20.

  The printer mechanism 21 includes a carriage 22 that reciprocates left and right along a guide 28 by a carriage belt 32 and a carriage motor 34, and mounted on the carriage 22, yellow (Y), magenta (M), cyan (C), and black (K) ink cartridges 26 that individually store inks of each color, a print head 24 that applies pressure to each ink supplied from each ink cartridge 26, and ink droplets that have been pressurized by the print head 24 are recorded on recording paper. A nozzle 23 serving as an emission hole for discharging to S and a platen 44 serving as a support member for supporting the recording paper S being printed are provided. In this embodiment, pigment ink is used as the ink. A linear encoder 25 that detects the position of the carriage 22 is disposed in the vicinity of the carriage 22, and the position of the carriage 22 can be managed using the linear encoder 25. Although not shown, the ink cartridge 26 is used for printing of cyan (C), magenta (M), yellow (Y), black (K), etc. containing a dye or pigment as a colorant in water as a solvent. The container is configured as a container for storing ink as a recording liquid, and is detachably attached to the carriage 22.

  Here, since many components (such as the carriage 22) of the printer mechanism 21 are well known, detailed description thereof will be omitted, and the print head 24 highly relevant to the present invention will be described below. As shown in FIG. 2, the print head 24 includes a nozzle row 43 in which a plurality of nozzles 23 that discharge inks of cyan (C), magenta (M), yellow (Y), and black (K) are arranged. Is provided. Here, all nozzles are collectively referred to as nozzles 23, all nozzle rows are collectively referred to as nozzle rows 43, cyan nozzles and nozzle rows are nozzles 23C and 43C, magenta nozzles and nozzle rows are nozzles 23M. The nozzle row 43M, the yellow nozzle and the nozzle row are referred to as a nozzle 23Y and a nozzle row 43Y, and the black nozzle and the nozzle row are referred to as a nozzle 23K and a nozzle row 43K. Hereinafter, description will be given using the nozzle 23K. In the print head 24, 180 nozzles 23 </ b> K are arranged along the transport direction of the recording paper S to form a nozzle row 43 </ b> K. The nozzle 23K is provided with a piezoelectric element 48 as a drive element for ejecting ink droplets. By applying a voltage to the piezoelectric element 48, the piezoelectric element 48 is deformed to pressurize and eject ink from the nozzle 23K. To do.

  The print head 24 includes a plurality of mask circuits 47 provided corresponding to the plurality of piezoelectric elements 48 that drive the respective nozzles 23K. The original signal ODRV and the print signal PRTn generated by the controller 70 are input to the mask circuit 47. Note that n at the end of the print signal PRTn is a number for specifying the nozzles included in the nozzle row. In this embodiment, since the nozzle row is composed of 180 nozzles, n is any number from 1 to 180. It becomes a numerical value. This original signal ODRV has a first pulse P1, a second pulse P2, a third pulse P3, as shown in the lower part of FIG. 2, within a period of one pixel (within the time during which the carriage 22 crosses the interval of one pixel). It consists of three drive waveforms. In the present embodiment, the original signal ODRV having these three drive waveforms as a repeating unit is referred to as one segment. When the original signal ODRV and the print signal PRTn are input, the mask circuit 47 transmits a necessary pulse among the first pulse P1, the second pulse P2, and the third pulse P3 based on these signals to the drive signal DRVn (n Is the same as n of the print signal PRTn) and is output toward the piezoelectric element 48 of the nozzle 23K. Specifically, when only the first pulse P1 is output from the mask circuit 47 to the piezoelectric element 48, one shot of ink droplet is ejected from the nozzle 23K, and a small size dot (small dot) is formed on the recording paper S. It is formed. When the first pulse P1 and the second pulse P2 are output to the piezoelectric element 48, two shots of ink droplets are ejected from the nozzle 23K, and medium-sized dots (medium dots) are formed on the recording paper S. The When the first pulse P1, the second pulse P2, and the third pulse P3 are output to the piezoelectric element 48, three shots of ink droplets are ejected from the nozzle 23K, and a large size dot (large size) is formed on the recording paper S. Dot) is formed. Thus, in the inkjet printer 20, it is possible to form dots of three types of sizes by adjusting the amount of ink ejected in one pixel section. The other color nozzles 23C, 23M, and 23Y and the nozzle rows 43C, 43M, and 43Y are the same as the nozzle 23K and the nozzle row 43K. Here, the print head 24 employs a method in which the piezoelectric element 48 is deformed to pressurize the ink, but the ink is generated by bubbles generated by heating the ink by applying a voltage to a heating resistor (for example, a heater). You may employ | adopt the system which pressurizes.

  As shown in FIG. 3, the paper feed mechanism 31 includes a recording paper insertion port 18 for inserting the recording paper S placed on the paper feed tray 14 and a recording paper S placed on the paper feed tray 14 as a print head. A paper feed roller 36 for feeding the recording paper S and roll paper to the print head 24, and a paper discharge roller 37 for discharging the recording paper S after printing. The paper feed roller 36, paper feed roller 35, and paper discharge roller 37 are driven by a drive motor 33 (see FIG. 1) via a gear mechanism (not shown). A plurality of recording sheets S are prevented from being fed at a time by the rotational driving force of the sheet feeding roller 36 and the frictional resistance of a separation pad (not shown). In FIG. 1, the conveyance direction of the recording sheet S is a direction from the back side toward the front side, and the movement direction of the carriage 22 that moves together with the print head 24 is a direction (main scanning direction) orthogonal to the conveyance direction of the recording sheet S. .

  The nozzle inspection device 50 forms the core of the present invention, and is provided in the inspection box 51 and an inspection box 51 in which ink droplets flying from the nozzles 23 of the print head 24 can land, as shown in FIG. An inspection area 52 provided at a predetermined distance from the print head 24, a voltage application circuit 53 for applying a voltage between the inspection area 52 and the print head 24, and a voltage for detecting the voltage of the inspection area 52 And a detection circuit 54. The inspection box 51 is a housing that is provided at a position off the left side from the printable area of the platen 44 and is a substantially rectangular parallelepiped with an upper portion opened. The inspection area 52 is provided in the inspection box 51, and an upper ink absorber 55 on which ink droplets directly land, and a lower ink that absorbs ink droplets that have been transmitted downward after landing on the upper ink absorber 55. The absorber 56 and a mesh-like electrode member 57 disposed between the upper ink absorber 55 and the lower ink absorber 56 are configured. The upper ink absorber 55 is made of a conductive sponge so as to have the same potential as the electrode member 57, and the surface thereof is an inspection region 52. This sponge is highly permeable so that the landed ink droplets can move down quickly, and here, an ester urethane sponge (trade name: Everlite SK-E, manufactured by Bridgestone Corporation) is used. Yes. The lower ink absorber 56 has higher ink retention than the upper ink absorber 55 and is made of a nonwoven fabric such as felt. Here, the nonwoven fabric (trade names: Kinocloth, Oji Kinocross Co., Ltd.) Made). The electrode member 57 is formed as a grid-like mesh made of a metal made of stainless steel (for example, SUS). For this reason, the ink once absorbed by the upper ink absorber 55 is absorbed and held by the lower ink absorber 56 through the gap between the grid-like electrode members 57. The voltage application circuit 53 is electrically connected via a DC power source (for example, 400 V), a resistance element (for example, 1 MΩ), and a switch SW so that the electrode member 57 is a positive electrode and the print head 24 is a negative electrode. . Here, since the electrode member 57 is in contact with the conductive upper ink absorber 55, the surface of the upper ink absorber 55, that is, the inspection region 52 is also at the same potential as the electrode member 57. The voltage detection circuit 54 is connected so as to detect the voltage of the electrode member 57 equated with the voltage of the inspection region 52, integrates and outputs the voltage signal of the electrode member 57, and the integration circuit 54a. An inverting amplification circuit 54b that inverts and amplifies the output signal and outputs the signal, and an A / D conversion circuit 54c that A / D converts the signal output from the inverting amplification circuit 54b and outputs the signal to the controller. The integration circuit 54a outputs a large voltage change by integrating the voltage change due to the flight / landing of a plurality of ink droplets since the voltage change due to the flight / landing of one ink droplet is small. The inverting amplifier circuit 54b inverts the sign of the voltage change and amplifies and outputs the signal output from the integrating circuit at a predetermined amplification factor determined by the circuit configuration. The A / D conversion circuit 54 c converts the analog signal output from the inverting amplification circuit 54 b into a digital signal and outputs the digital signal to the controller 70.

  As shown in FIG. 1, the cap device 40 is used when sealing the nozzles 23 in order to prevent the nozzles 23 from being dried during a printing pause or the like. The cap device 40 is operated so as to cover the nozzle formation surface of the print head 24 when the print head 24 moves together with the carriage 22 to the right end (referred to as a home position). The cap device 40 is connected to a suction pump (not shown). For example, when nozzle clogging is detected by the nozzle inspection device 50, the negative pressure of the suction pump is applied to the nozzle forming surface of the print head 24 sealed by the cap device 40 as necessary. The ink clogged from 23 is sucked and discharged. Note that the waste ink discharged and collected is stored in a waste liquid tank (not shown).

  As shown in FIG. 1, the controller 70 is configured as a microprocessor centered on the CPU 72, and includes a ROM 73 that stores various processing programs, a RAM 74 that temporarily stores data and stores data, A flash memory 75 that can write and erase data, an interface (I / F) 79 that exchanges information with an external device, and an input / output port (not shown) are provided. The ROM 73 stores processing programs for a main routine, a preliminary discharge routine, a nozzle inspection routine, and a print processing routine, which will be described later. The RAM 74 is provided with a print buffer area, and print data transmitted from the user PC 10 via the I / F 79 is stored in the print buffer. In addition to the voltage signal output from the voltage detection circuit 54 of the nozzle inspection device 50 and the position signal of the carriage 22 from the linear encoder 25 being input to the controller 70 via an input port (not shown), the user PC 10 A print job or the like output from is input via the I / F 79. Further, from the controller 70, a control signal to the print head 24 (including the mask circuit 47 and the piezoelectric element 48), a control signal to the drive motor 33, a drive signal to the carriage motor 34, and an operation control signal to the cap device 40. Are output via an output port (not shown), and print status information to the user PC is output via the I / F 79.

  Next, the operation of the ink jet printer 20 of the present embodiment configured as described above will be described. Here, first, the operation of the main routine will be described with reference to FIG. FIG. 5 is a flowchart of a main routine executed by the CPU 72 of the controller 70. This routine is executed by the CPU 72 at predetermined timings (for example, every several msec) after the power of the inkjet printer 20 is turned on. When this routine is started, the CPU 72 first determines whether there is a print job waiting to be printed (step S100). Since the print job received from the user PC 10 is stored in the print buffer area formed in the RAM 74 and becomes a print job waiting to be printed, when the print job is received, it can be printed immediately as well as during printing. Even so, the print job is waiting for printing. If there is no print job waiting for printing in step S100, the main routine is terminated.

  On the other hand, when there is a print job waiting for printing in step S100, the print quality level included in the print job is read (step S102). The print quality level is determined by the print mode set by the printer driver of the user PC 10 or the operation panel (not shown) of the inkjet printer 20, and specifically, high print quality is required when the print mode is the “fast” mode. The print quality level is set to a low level, and the print quality level is set to a high level assuming that a high print quality is required in the “clean” mode. The “fast” mode is often set when the print speed is more important than the print quality (for example, when checking an original containing only characters), and printing is performed with large dots. The amount of movement in one transport direction is also large. On the other hand, the “clean” mode is a mode (image quality priority mode) that is often set when the print quality is more important than the print speed, for example, when printing a photograph. The amount of movement in the transport direction is small.

  After step S102, the inspection timing corresponding to the print quality level included in the current print job is read from the inspection timing correspondence table in FIG. 6 and stored in the RAM 74 as the current inspection timing (step S104). . The inspection timing correspondence table in FIG. 6 is stored in the ROM 73, and the inspection timing, which is a timing for starting a nozzle inspection routine described later, is set according to the number of printing passes. The printing pass is an operation of ejecting ink from the nozzle 23 to the recording paper S while the print head 24 moves from the left end to the right end (or vice versa) of the recording paper S. Since there is a correlation between the number of ink ejections from the nozzles 23 and the occurrence of nozzle clogging, the inspection timing is defined here by the number of printing passes closely related to the number of ink ejections from the nozzles 23. . In the table of FIG. 6, the inspection timing corresponding to the low-level print quality level (“fast” mode) is 150 passes, and the inspection timing corresponding to the high-level print quality level (“clean” mode) is 100 passes. It has become. For this reason, the inspection frequency is higher in the “clean” mode than in the “fast” mode. After step S104, the print pass number counter is reset to zero (step S106), and print data for one page is read (step S108). The print pass number counter is a counter provided in a predetermined area of the RAM 74, and is incremented by 1 every time one print pass is completed in a print processing routine described later.

  Subsequently, a print processing routine is executed (step S110). FIG. 7 is a flowchart of this print processing routine. When the print processing routine is started, the CPU 72 first executes a paper feed process (step S200). The paper feed process is a process of conveying the recording paper S placed on the paper feed tray 14 to the paper feed roller 35 by driving the drive motor 33 to rotate the paper feed roller 36 (see FIG. 3). Next, the CPU 72 drives the carriage motor 34 to eject the ink from the print head 24 while moving the carriage 22 leftward in FIG. 1 from the home position or the like, and executes forward printing based on the print data (step S202). Then, after the end of the forward printing, the printing pass number counter is incremented by 1 (step S204). Subsequently, the CPU 72 determines whether or not there is print data to be printed on the recording paper S currently being printed (step S206). The roller 35 is rotationally driven to execute a conveyance process for conveying the recording paper S by a predetermined amount (step S208), and ink is ejected from the print head 24 while the carriage 22 is moved rightward in FIG. Return pass printing is executed based on the print data (step S210), and after the return pass printing is completed, the print pass number counter is incremented by 1 (step S212). Subsequently, the CPU 72 determines whether or not there is print data to be printed on the recording sheet S currently being printed (step S214). A conveying process for rotating the roller 35 to convey the recording paper S by a predetermined amount is executed (step S216), and the processes after step S202 are executed. On the other hand, when there is no print data to be printed on the recording sheet S that is currently being printed in step S206 or step S214, the CPU 72 executes a discharge process for discharging the recording sheet S (step S218). The paper discharge process is a process of rotating the paper discharge roller 37 to discharge the recording paper S to the paper discharge tray. After step S218, this print processing routine is terminated. Thereby, printing for one page of the print job is completed.

  Now, returning to the main routine of FIG. 5, after performing the print processing routine of step S110, it is determined whether or not the inspection timing has been reached based on the count value of the print pass number counter (step S112). That is, the count value of the print pass number counter is compared with the print pass number set in step S104 as the current inspection timing, and when the former reaches the latter (that is, when the former is greater than or equal to the latter). Then, a nozzle inspection routine is executed (step S114). FIG. 8 is a flowchart of this nozzle inspection routine. When the nozzle inspection routine is started, the CPU 72 first turns on the switch SW of the voltage application circuit 53 to generate a predetermined potential difference between the inspection region 52 and the print head 24, and at the current inspection position, that is, the nozzle 23. The position of the inspection area 52 from which ink is ejected is acquired (step S300). Here, since the solid matter contained in the ink may be deposited on the surface of the inspection area 52 due to the ejection of the ink, the inspection position is set to change every time the nozzle inspection routine is executed. FIG. 9 is an explanatory diagram of the inspection position in the nozzle inspection process. In FIG. 9, a plurality of inspection positions p1, p2, p3, and p4 are set. In one nozzle inspection routine, each nozzle row 43 has a variation in the detected value of the dielectric voltage due to the difference in the inspection position. The ink is set to be ejected to the same inspection position. For example, when the current nozzle inspection is performed at the inspection position p1, the nozzle row 43Y is first positioned so as to face the inspection position p1, and ink droplets are ejected from the nozzles 23Y included in the nozzle row 43Y. Next, the nozzle row 43M is positioned so as to face the inspection position p1, and ink droplets are ejected from the nozzles 23M included in the nozzle row 43M. Thereafter, the nozzle rows 43C and 43K are similarly tested at the inspection position p1. Ink droplets are ejected from the nozzles 23C and 23K. Further, the ink is ejected to a position different from the current inspection position at the next inspection position so that the solid content of the ink is not excessively accumulated only at a certain inspection position. For example, when the current nozzle inspection is performed at the inspection position p1, the next nozzle inspection is performed at the inspection position p2. Now, referring back to FIG. 8, after acquiring the current inspection position in step S300, the CPU 72 drives the carriage motor 34, and among the nozzle arrays 43 of the print head 24, the nozzle array 43 to be inspected becomes the current inspection position. The carriage 22 is moved so as to oppose (step S310), and the ink charged from the nozzle 23 via the mask circuit 47 and the piezoelectric element 48 (see FIG. 2) of one nozzle 23 in the nozzle row 43 to be inspected. Drops are ejected (step S320).

  Here, a change in voltage in the electrode member 57 when the charged ink droplets fly from the nozzles 23 of the print head 24 and reach the inspection region 52 including the upper ink absorber 55 will be described with reference to FIG. FIG. 10 is an explanatory diagram of the principle that an induced voltage is generated by electrostatic induction. As shown in FIG. 10A, the ink droplet before flying from the nozzle 23 by the print head 24 is negatively charged by the voltage application circuit 53. In addition, since the print head 24 and the inspection area 52 are arranged at a distance and a predetermined potential difference is generated between them, a predetermined electric field strength (= potential difference / distance) is generated between them. Yes. For this reason, as shown in FIG. 10B, as the negatively charged ink droplets fly from the nozzle 23 and approach the upper ink absorber 55, the surface of the upper ink absorber 55 is positively applied by electrostatic induction. The charge increases. As a result, the voltage between the print head 24 and the electrode member 57 becomes higher than the initial voltage value due to the induced voltage generated by electrostatic induction. Thereafter, as shown in FIG. 10C, when the negatively charged ink droplet reaches the upper ink absorber 55, the positive charge of the upper ink absorber 55 is neutralized by the negative charge of the ink droplet. As a result, the voltage between the print head 24 and the electrode member 57 is lower than the initial voltage value. Thereafter, the voltage between the print head 24 and the electrode member 57 returns to the applied voltage value. The amplitude of the output signal at this time depends not only on the distance from the print head 24 to the upper ink absorber 55 (inspection region 52), but also on the presence or size of flying ink droplets. For this reason, when the nozzle 23 is clogged and the ink droplet does not fly or the ink droplet is smaller than a predetermined size, the amplitude of the output signal becomes smaller than the normal time. The presence or absence of clogging can be determined. In the present embodiment, even if the ink droplet has a predetermined size, the amplitude of the output signal from the ink droplet for one shot is extremely small. Therefore, one segment of the first to third pulses P1, P2, representing the drive waveform. By performing the operation of outputting all of P3 eight times, ink droplets for 24 shots are ejected. As a result, the output signal becomes an integrated value of ink droplets for 24 shots, and thus a sufficiently large output waveform can be obtained from the voltage detection circuit 54. Note that the direction of the amplitude of the signal output from the voltage detection circuit 54 is reversed because it passes through the inverting amplification circuit 54b.

  Returning to FIG. 8, after discharging the charged ink droplets from the nozzle 23 via the mask circuit 47 or the piezoelectric element 48 of one nozzle 23 in the nozzle row 43 to be inspected in this way, the CPU 72 determines the voltage. It is determined whether the amplitude of the signal output from the detection circuit 54, that is, the output level is equal to or higher than the threshold value Vthr (step S330). As shown in FIG. 11, the threshold value Vthr exceeds the output level when ink for 24 shots is normally ejected, and exceeds noise due to noise or the like when ink for 24 shots is not ejected normally. It is a value determined empirically so that nothing happens. When the output level is less than the threshold value Vthr in step S330, it is considered that an abnormality such as clogging has occurred in the current nozzle 23, and information for identifying the nozzle 23 (for example, which nozzle in which nozzle row is located) Information) is stored in a predetermined area of the RAM 74 (step S340). After step S340 or when the output level is equal to or higher than the threshold value Vthr in step S330 (that is, when the current nozzle 23 is normal), the CPU 72 inspects all the nozzles 23 included in the nozzle row 43 currently being inspected. If there is an uninspected nozzle 23 in the currently inspected nozzle row (step S350), the nozzle 23 to be inspected is updated to an uninspected nozzle (step S360), and then again in step S320. Perform the following processing. On the other hand, when all the nozzles 23 included in the nozzle row 43 currently inspected are inspected in step S350, it is determined whether or not all the nozzle rows 43 included in the print head 24 have been inspected (step S370). ) When there is an uninspected nozzle row 43, the nozzle row 43 to be inspected is updated to the uninspected nozzle row 43 (step S380), and then the processing after step S310 is performed again. On the other hand, when all the nozzle rows 43 included in the print head 24 have been inspected in step S370, the switch SW of the voltage application circuit 53 is turned off (step S390), and this nozzle inspection routine ends. By executing this routine, if there is a nozzle 23 in which an abnormality has occurred among all the nozzles 23 arranged in the print head 24, information for specifying the nozzle 23 is stored in the predetermined area of the RAM 74. If there is no nozzle 23 in which an abnormality has occurred, nothing is stored.

  Now, returning to the main routine of FIG. 5, after executing the nozzle inspection routine (step S114) described above, the CPU 72 sets the print pass number counter to zero in order to recount the number of print passes from 1 in the next print processing routine. Reset (step S116). Thereafter, it is determined based on the stored contents of a predetermined area of the RAM 74 whether or not there is a nozzle 23 having an abnormality among all the nozzles 23 arranged in the print head 24 (step S118). When there is a nozzle 23 that is present, the print head 24 is cleaned in consideration of clogging, but before that, the number of cleanings performed to eliminate the abnormality is a predetermined upper limit number (for example, 3 times) is determined (step S120). When the number of cleanings is less than the upper limit number, the print head 24 is cleaned (step S122). Specifically, the carriage motor 34 is driven to move the carriage 22 until the print head 24 comes to the home position facing the cap device 40, and the cap device 40 is operated so that the cap device 40 forms the nozzles of the print head 24. After covering the surface, the negative pressure of a suction pump (not shown) is applied to the nozzle forming surface to suck and discharge the clogged ink from the nozzle 23. After executing this cleaning, the process returns to step S114 again to check whether the abnormality of the nozzle 23 has been eliminated. In this step S114, only the nozzle 23 in which an abnormality has occurred may be reinspected, but the nozzle 23 that was normal at the time of cleaning may be clogged for some reason. Re-inspect all nozzles 23. On the other hand, when the number of cleanings performed in step S120 has reached the upper limit, it is assumed that the nozzle 23 in which the abnormality has occurred is not normalized even if cleaning is performed, and an error message is displayed on an operation panel (not shown) (step S120). S124), this main routine is terminated. On the other hand, when there is no abnormal nozzle 23 in step S118, it is determined whether there is print data for the next page for the current print job (step S126). The processing after 108 is executed, and when there is no print data for the next page, this main routine is terminated.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. The mask circuit 47 and the piezoelectric element 48 of the present embodiment correspond to the driving means of the present invention, the platen 44 corresponds to the printable area, the inspection area 52 corresponds to the inspection area, and the voltage detection circuit 54 corresponds to the detection means. The CPU 72 corresponds to the inspection timing setting means and the control means, the paper feed roller 36 and the paper feed roller 35 correspond to the transport means, the carriage 22, the carriage belt 32 and the carriage motor 34 correspond to the head moving means, and the cap. The device 40 corresponds to a cleaning unit. In this embodiment, an example of the nozzle inspection method of the present invention is also clarified by describing the operation of the ink jet printer 20.

  According to the ink jet printer 20 of the present embodiment described in detail above, the inspection timing for starting the nozzle inspection routine for inspecting the nozzle 23 while discharging ink from the nozzle 23 is set based on the print mode related to the print quality level. Therefore, the inspection timing can be advanced or delayed according to the print quality level. Therefore, the inspection of the nozzle 23 can be executed at an appropriate timing. Specifically, when the print quality level is high, the frequency of inspection of the nozzles 23 increases, and even if a problem occurs in the nozzles 23, it is possible to cope with the problem early. Can be suppressed as much as possible. On the other hand, when the print quality level is low, the frequency of the inspection of the nozzles 23 is lowered, so that the printing time due to the inspection of the nozzles 23 can be minimized.

  In addition, since the nozzle inspection routine is always executed after the cleaning is performed, it can be confirmed whether or not the nozzles 23 in which an abnormality such as clogging has occurred due to the execution of the cleaning have been normalized.

  Further, when performing the nozzle inspection, the print head 24 is arranged on the inspection region 52 so that the charged ink is discharged from the nozzle 23 in a state where a predetermined potential difference is generated between the print head 24 and the inspection region 52. When the mask circuit 47 and the piezoelectric element 48 are controlled, whether the ink is actually ejected is determined by the print head 24 and the inspection area 52 until the charged ink jumps from the nozzle 23 and lands on the inspection area 52. Since the determination is based on the voltage change between the nozzles, the nozzle inspection can be performed with high accuracy. Furthermore, when a nozzle inspection is performed during printing for one page, there is a risk that the color tone may change before or after the nozzle inspection is performed on that page, and printing unevenness may occur. In particular, ink is ejected sequentially from each nozzle. If the nozzle inspection is performed, there is a concern that the inspection time will be long, but in the above-described embodiment, the nozzle inspection is not performed in the middle of printing for one page. Absent.

[Second Embodiment]
Next, a second embodiment will be described. The second embodiment is an inkjet printer 20 having the same configuration as that of the first embodiment, but the processing content of the main routine is different from that of the first embodiment. Therefore, here, the description will focus on the differences from the first embodiment.

  First, the operation of the main routine will be described with reference to FIG. FIG. 12 is a flowchart of a main routine executed by the CPU 72 of the controller 70. This routine is executed by the CPU 72 at predetermined timings (for example, every several msec) after the power of the inkjet printer 20 is turned on. When this routine is started, the CPU 72 first determines whether or not there is a print job waiting for printing (step S400). If there is no print job waiting for printing, the CPU 72 ends the main routine as it is. To do. On the other hand, when there is a print job waiting for printing in step S400, the print quality level included in the print job is read (step S402), and the inspection timing corresponding to the print quality level included in the print job is set. The data is read from the inspection timing correspondence table of FIG. 13 and stored in the RAM 74 as the current inspection timing (step S404). The inspection timing correspondence table of FIG. 13 is stored in the ROM 73, and the print quality level is determined by the print mode as in the first embodiment, but the inspection timing is set by the number of ink ejections unlike the first embodiment. ing. The inspection timing corresponding to the low-level print quality level (“fast” mode) is 15000 ink discharge times, and the inspection timing corresponding to the high-level print quality level (“clean” mode) is 10,000 ink discharge times. It has become. For this reason, the inspection frequency is higher in the “clean” mode than in the “fast” mode. The number of ink ejections can be set, for example, to the number of times of driving the piezoelectric element 48 corresponding to each nozzle 23. After step S404, the ink discharge counter provided for each color is reset to zero (step S406), and print data for one page is read (step S408).

  Subsequently, a print processing routine is executed (step S410). FIG. 14 is a flowchart of this print processing routine. When the print processing routine is started, the CPU 72 first executes a paper feed process (step S500), then executes forward pass printing and counts the number of ink ejections from the nozzles 23 for each color (step S502). That is, each time ink of a certain color is ejected once from the nozzle 23, the ink ejection number counter corresponding to that color is incremented by one. The ink discharge number counter for each color is provided in the RAM 74. Subsequently, the CPU 72 determines whether or not there is print data to be printed on the recording paper S currently being printed (step S504). (Step S506), and then the backward printing is executed and the number of ink ejections from the nozzles 23 is counted for each color (step S508). Subsequently, the CPU 72 determines whether or not there is print data to be printed on the recording paper S currently being printed (step S510). (Step S512), and the processing after step S502 is executed. On the other hand, when there is no print data to be printed on the recording sheet S that is currently being printed in step S504 or step S510, the CPU 72 executes a paper discharge process (step S514), and ends this print processing routine. Thereby, printing for one page of the print job is completed. Note that the paper feed process, the forward path printing, the backward path printing, the transport process, and the paper discharge process are the same as those in the first embodiment, and a detailed description thereof will be omitted here.

  Returning to the main routine of FIG. 12, after performing the printing process routine of step S410, it is determined whether or not the inspection timing has been reached based on the count value of the ink discharge number counter for each color (step S412). That is, the count value of the ink ejection number counter for each color is compared with the number of ink ejections set in step S404 as the current inspection timing, and the ink ejection number counter of any color is used as the inspection timing. When the number of times has been reached, a nozzle inspection routine is executed for the nozzle of that color (step S414). The nozzle inspection routine here is the nozzle inspection routine of the first embodiment in that only the nozzle row 43 of the color whose count value of the ink discharge number counter reaches the number of ink discharges as the inspection timing is the nozzle row to be inspected. However, since the rest is the same as the nozzle inspection routine of the first embodiment, detailed description thereof is omitted here. An example of the nozzle inspection routine here is shown in FIG. Steps S600 to S660 of FIG. 15 are the same as steps S300 to S360 of the nozzle inspection routine of the first embodiment, and step S690 is the same as step S390.

  Returning to the main routine of FIG. 12, after performing the nozzle inspection routine (step S414) described above, the ink ejection number counter of the color for which the nozzle inspection has been performed this time is reset to zero (step S416), and the nozzle for that color It is determined whether there is an abnormal nozzle 23 among the nozzles 23 arranged in the row 43 based on the stored contents of a predetermined area of the RAM 74 (step S418), and the abnormal nozzle 23 is detected. In some cases, the print head 24 is cleaned, but before that, it is determined whether the number of cleanings performed to eliminate the abnormality has reached a predetermined upper limit number (step S420). When the number of cleanings is less than the upper limit number, the print head 24 is cleaned (step S422). Since the cleaning is the same as in the first embodiment, description thereof is omitted, but here, only the nozzle row 43 of the color subjected to the nozzle inspection is cleaned. However, all the nozzle rows 43 may be cleaned. After executing this cleaning, the process returns to step S414 again to check whether the abnormality of the nozzle 23 has been eliminated. On the other hand, if the number of cleanings performed in step S420 has reached the upper limit, it is considered that the nozzle 23 in which an abnormality has occurred is not normalized even if cleaning is performed, and an error message is displayed on an operation panel (not shown) (step S420). S424), the main routine is terminated. On the other hand, when there is no abnormal nozzle 23 in step S418, it is determined whether there is print data for the next page for the current print job (step S426). The processing after 408 is executed, and when there is no print data for the next page, this main routine is terminated.

  According to the inkjet printer 20 of the present embodiment described in detail above, the same effects as those of the first embodiment described above can be obtained. In addition, since it is determined whether or not nozzle inspection is necessary for each color, it is not necessary to waste ink for colors that do not require nozzle inspection.

[Third Embodiment]
Next, a third embodiment will be described. The third embodiment is an inkjet printer 20 having the same configuration as that of the first embodiment, but the processing content in the main routine is different from that of the first embodiment. Therefore, here, the description will focus on the differences from the first embodiment.

  First, the operation of the main routine will be described with reference to FIG. FIG. 16 is a flowchart of a main routine executed by the CPU 72 of the controller 70. This routine is executed by the CPU 72 at predetermined timings (for example, every several msec) after the power of the inkjet printer 20 is turned on. When this routine is started, the CPU 72 first determines whether or not there is a print job waiting for printing (step S700). If there is no print job waiting for printing, the CPU 72 ends the main routine as it is. To do. On the other hand, when there is a print job waiting for printing in step S700, the print quality level included in the print job is read (step S702), and the inspection timing corresponding to the print quality level included in the print job is set. As in the first embodiment, the data is read from the inspection timing correspondence table of FIG. 6 and stored in the RAM 74 as the current inspection timing (step S704). Thereafter, the print pass number counter is reset to zero (step S706), and print data for one page is read (step S708). Steps S700 to S708 are the same as steps S100 to S108 of the main routine of FIG. 5 of the first embodiment.

  Subsequently, a print processing routine is executed (step S710). FIG. 17 is a flowchart of this print processing routine. When the print processing routine is started, the CPU 72 first executes a paper feed process (step S800), and determines whether the abnormality occurrence flag F is zero or a value 1 (step S802). The abnormality occurrence flag F is a flag that is set to 1 when an abnormal nozzle 23 that does not eject ink is found in a nozzle inspection routine that will be described later, and is zero at other times. Resets to zero each time is turned on. If the abnormality occurrence flag F is zero in step S802, normal forward printing is executed (step S804). The forward printing at this time is the same as the forward printing in the first embodiment. On the other hand, when the abnormality occurrence flag F is a value of 1 in step S802, cleaning may not be performed because cleaning may be performed before and after the cleaning, and an abnormal nozzle that does not eject ink instead. The forward printing is performed while performing the process of complementing the portion where the ink should have been ejected by other normal nozzles 23 (step S806). For such complementation, for example, the contents disclosed in Japanese Patent Application Laid-Open No. 2000-263772 can be adopted, but the details are omitted here. Now, after the forward printing is performed in step S804 or S806, the printing pass number counter is incremented by one (step S808). Subsequently, the CPU 72 determines whether or not the inspection timing has been reached based on the count value of the print pass number counter (step S810). That is, the count value of the print pass counter is compared with the print pass number set in step S704 as the current inspection timing, and when the former reaches the latter (that is, when the former is greater than or equal to the latter). Then, a nozzle inspection routine is executed (step S812).

  FIG. 18 is a flowchart of this nozzle inspection routine. Steps S900 to S990 of this nozzle inspection routine are the same as steps S300 to S390 of the nozzle inspection routine of the first embodiment shown in FIG. Then, the explanation is omitted. After the switch SW of the voltage application circuit 53 is turned off in step S990, the print pass number counter is reset to zero (step S992), and the nozzle 23 in which an abnormality has occurred among all the nozzles 23 arranged in the print head 24. Whether or not there is a nozzle 23 in which an abnormality has occurred, a value 1 is set to the abnormality flag F (step S996), and if there is no nozzle 23 in which an abnormality has occurred The abnormality occurrence flag F is reset (step S998), and this routine is finished.

  Returning to the print processing routine of FIG. 17, after the nozzle inspection routine of step S812 or when it is not the inspection timing in step S810, it is determined whether there is print data to be printed on the recording paper S currently being printed. If there is data to be printed on the recording sheet S that is currently being printed (step S814), the carrying process is executed (step S816), and it is determined whether the abnormality occurrence flag F is zero or the value 1 (step S818). When the abnormality occurrence flag F is zero, normal return pass printing is executed (step S820). The return pass printing at this time is the same as the return pass printing in the first embodiment. On the other hand, if the abnormality occurrence flag F is 1 in step S818, that is, if there is a nozzle 23 that does not eject ink, the cleaning may not be performed because the color may change before and after the cleaning. Instead, the return pass printing is performed while the nozzle 23 that does not eject ink is supposed to eject ink and is complemented by another normal nozzle 23 (step S822). For such complementation, for example, the contents disclosed in Japanese Patent Application Laid-Open No. 2000-263772 can be adopted, but the details are omitted here. Then, after performing the backward pass printing in step S820 or S822, the print pass number counter is incremented by 1 (step S824), and it is determined whether or not the inspection timing has been reached based on the count value of the print pass number counter (step S824). S826) When the inspection timing is reached, the nozzle inspection routine of FIG. 18 described above is executed (step S828). Then, after step S828 or when it is determined in step S826 that it is not the inspection timing, it is determined whether there is print data to be printed on the recording sheet S that is currently printed (step S830), and the recording that is currently being printed. When there is data to be printed on the paper S, the carrying process is executed (step S832). On the other hand, if there is no data to be printed on the recording sheet S that is currently being printed in step S814 or S830, this print processing routine is terminated. Note that the paper feed process, the forward path printing, the backward path printing, the transport process, and the paper discharge process are the same as those in the first embodiment, and a detailed description thereof will be omitted here.

  Returning to the main routine of FIG. 16, after performing the print processing routine of step S710, it is determined whether the abnormality occurrence flag F is zero or value 1 (step S712), and when the abnormality occurrence flag F is value 1, Before the print head 24 is cleaned, it is determined whether or not the number of cleanings performed to eliminate the abnormality has reached a predetermined upper limit (step S720). When the number of cleanings is less than the upper limit number, the print head 24 is cleaned (step S722). After executing this cleaning, the above-described FIG. The nozzle inspection routine is executed (step S724), and then the process returns to step S712. Since the cleaning is the same as that of the first embodiment, the description thereof is omitted. On the other hand, when the number of cleanings performed in step S720 has reached the upper limit number, the nozzle 23 in which an abnormality has occurred is regarded as not normalizing even if cleaning is performed, and an error message is displayed on an operation panel (not shown) (step S120). S726), the main routine is terminated. On the other hand, if there is no abnormal nozzle 23 in step S712, it is determined whether there is print data for the next page for the current print job (step S728). The processing after 708 is executed, and when there is no print data for the next page, this main routine is terminated.

  According to the inkjet printer 20 of the present embodiment described in detail above, the same effects as those of the first embodiment described above can be obtained. In addition, since the nozzle inspection is not performed after the printing of one page is completed, but every forward printing or backward printing, an abnormal nozzle that does not eject ink can be detected at an early stage. Complementary processing) can be performed, so that occurrence of a printing error without ink being ejected can be suppressed as much as possible.

[Other Embodiments]
The main routine of the first embodiment shown in FIG. 5 may be changed as shown in FIG. That is, instead of performing the process of reading print data for one page and executing the print process routine (steps S108 and S110) after resetting the print pass number counter in step 106 as shown in FIG. As described above, the determination may be performed after it is determined in step S118 that there is no abnormal nozzle 23 among all the nozzles 23 arranged in the print head 24. In this case, the same effect as the first embodiment can be obtained.

  The processing in steps S1100 to S1160 shown in FIG. 20 may be added at the beginning of the main routine of the first embodiment described above, that is, before the determination block for determining whether there is a print job waiting to be printed. That is, the time elapsed since the ink was ejected from the nozzles 23 of the print head 24 last time was measured as the standing time, and the standing time was predetermined time T (for example, the ink dried and clogged around the opening of the nozzle 23). Whether or not there is a print job waiting for printing is determined (step S1100). If the leaving time does not exceed the predetermined time T, it is determined whether or not there is a print job waiting for printing. Proceed to the determination (step S100). On the other hand, when the leaving time exceeds the predetermined time T, the nozzle inspection routine of FIG. 8 is executed (step S1110), and then the printing pass number counter is reset (step S1120), and there is an abnormal nozzle 23 that does not eject ink. It is determined whether or not (step S1130), and if there is no abnormal nozzle 23, the process proceeds to step S100. On the other hand, if there is an abnormal nozzle 23 in step S1130, it is determined whether or not the upper limit of the number of cleanings for eliminating the abnormality has reached the upper limit (step S1140). If the upper limit has not been reached, cleaning is performed (step S1140). (S1150), it returns to step S1110 again. On the other hand, when the number of cleanings for eliminating the current abnormality reaches the upper limit in step S1140, an error message is displayed on an operation panel (not shown) (step S1160), and the main routine is terminated. In this way, by adding the time when the leaving time exceeds the predetermined time T as the inspection timing, the ink clogging of the nozzles 23 caused by the leaving can be detected and eliminated at an early stage. Note that the processing of steps S1100 to S1160 may be added to the beginning of the main routine of the embodiment other than the first embodiment.

  In the second embodiment described above, the number of ink ejections from the nozzles is counted for each color, but the number of ink ejections is counted up when ink is ejected from any nozzle regardless of the color. The nozzle inspection routine may be executed when the number of ink ejections reaches the inspection timing set based on the inspection timing correspondence table shown in FIG.

  In each embodiment described above, the print quality level is determined by the print mode, but may be determined by the paper type. For example, when the paper type is plain paper, the print quality level is set to a low level on the assumption that high print quality is not required, and when the paper type is photo-only paper, the print quality level is set to be high on the assumption that a high print quality is required. Level. An example of the inspection timing correspondence table at this time is shown in FIG. In this table, the inspection timing corresponding to plain paper is 150 passes in terms of the number of print passes, and the inspection timing corresponding to photo-dedicated paper is 100 passes in terms of the number of print passes. For this reason, the inspection frequency is higher for photo-only paper than for plain paper.

  In each embodiment described above, the inspection timing is set according to the number of printing passes and the number of ink ejections from the nozzles. However, the number of printed pages and the actual printing time (for example, the sum of the time required for forward printing and the time required for backward printing) ) May set the inspection timing.

  In each of the above-described embodiments, the cleaning is performed at the time of (1) initial filling (when the ink cartridge 26 is first mounted and the nozzle 23 is filled with ink after purchasing the printer), and (2) the operator is the user When the printer driver of the PC 10 or the operation panel (not shown) of the inkjet printer 20 instructs cleaning execution and the inkjet printer 20 receives the instruction, (3) the time measured by the built-in timer has reached a predetermined cleaning execution timing. (4) When the ink cartridge 26 is replaced, the nozzle inspection routine may be executed every time cleaning is performed. By always executing the nozzle inspection routine after the cleaning is performed, it is possible to confirm whether or not an abnormal nozzle that does not eject ink has been normalized by the cleaning.

  In each of the above-described embodiments, when there is an abnormal nozzle that does not eject ink, when cleaning is performed a plurality of times to eliminate the abnormality, the suction force of the cap device 40 increases as the number of times increases. It may be. For example, when an abnormal nozzle 23 is present in step S118 of the main routine of FIG. 5, the first cleaning is performed with a “weak” suction force, and when the abnormality is resolved by the first cleaning, “fast” In the “mode”, the inspection timing is set to 150 passes, and in the “clean” mode, the inspection timing is set to 100 passes. On the other hand, when the abnormality is not resolved by the first cleaning, when the second cleaning is performed, the “medium” suction force is used. When the abnormality is resolved by the second cleaning, the inspection is performed in the “fast” mode. The timing is 175 passes for the number of print passes, and the inspection timing is 125 passes for the number of print passes in the “clean” mode. On the other hand, when the abnormality is not resolved by the second cleaning, the “strong” suction force is used when the third cleaning is performed, and when the abnormality is resolved by the third cleaning, the inspection is performed in the “fast” mode. The timing is set to 200 passes for the number of print passes, and the inspection timing is set to 150 passes for the number of print passes in the “clean” mode. The setting at this time is shown in FIG. For example, when the suction force of cleaning when the abnormal nozzles 23 are eliminated is “strong”, the number of print passes so that the next inspection timing comes later because the ink is often sufficiently distributed to the nozzles 23. Is set to a large value, and the cleaning suction force when the abnormal nozzles 23 are eliminated is “weak”, the ink may not be sufficiently distributed to the nozzles 23, so the next inspection timing comes early. In this way, the print pass number is set to a small value. Note that the cleaning suction force may be changed by the operator using a printer driver of the user PC 10 or an operation panel (not shown) of the ink jet printer 20, and in that case, the cleaning suction force may be changed regardless of the number of cleanings in the table of FIG. The inspection timing may be set accordingly.

  In each of the above-described embodiments, when the nozzle inspection is performed, the print head 24 is arranged on the inspection region 52 and the ink charged in a state where a predetermined potential difference is generated between the print head 24 and the inspection region 52 is the nozzle 23. When the mask circuit 47 and the piezoelectric element 48 are controlled so as to be ejected from the print head 24, the charged head 24, which is generated by electrostatic induction until the charged ink flies from the nozzle 23 and lands on the inspection area 52. Whether or not ink has actually been ejected from the nozzles 23 is determined based on the voltage change between them, but may be determined as follows. That is, a light emitting element 102 and a light receiving element 104 are installed in the inspection area 52 as shown in FIG. 23, and laser light emitted from the light emitting element 102 and incident on the light receiving element 104 and ink ejected from a predetermined nozzle 23 are generated. After the print head 24 is arranged at the intersecting position and operated so that ink is ejected from the nozzle 23, it is determined whether or not the laser beam is blocked by the ink based on the output signal of the light receiving element 104, and is blocked. In this case, it is assumed that ink is actually ejected from the nozzle 23. Thereafter, the print head 24 is arranged at a position where the ink and the light beam ejected from the next nozzle 23 intersect, and it is inspected whether the ink is actually ejected in the same manner as before. Even in this case, it is possible to inspect nozzles using ink. Details of such an inspection method are disclosed in JP-A-2005-35309.

  In each of the above-described embodiments, a voltage is applied to the inspection area 52 side of the print head 24 and the inspection area 52 and the voltage of the inspection area 52 is detected by the voltage detection circuit 54. However, the print head 24 and the inspection area 52 are detected. Among them, a voltage may be applied to the print head 24 side to detect the voltage of the print head 24, or a voltage may be applied to the print head 24 side of the print head 24 and the inspection area 52 to change the voltage in the inspection area 52. The voltage may be detected, or the voltage of the print head 24 may be detected by applying a voltage to the inspection area 52 side of the print head 24 and the inspection area 52.

  In each of the above-described embodiments, the inspection region 52 of the nozzle inspection device 50 is configured by the upper ink absorber 55, the lower ink absorber 56, and the electrode member 57, but is configured by only the electrode member 57. One of the upper ink absorber 55 and the lower ink absorber 56 may be omitted. Further, although the inspection box 51 is provided independently of the other members, the cap device 40 may also serve as the inspection box, or the platen 44 may also serve as the inspection box. In particular, when the cap device 40 is also used as an inspection box, it is preferable because space can be saved and the number of parts can be reduced.

  In each of the above-described embodiments, the print quality level is determined by the print mode set by the printer driver of the user PC 10 or the operation panel (not shown) of the inkjet printer 20, but the paper type is detected by the paper type detection sensor of the inkjet printer 20. And a print mode suitable for the paper type is automatically set, and the print quality level may be determined by the print mode.

  In the first embodiment described above, as shown in FIG. 6, the inspection timing corresponding to the low-level print quality level (“fast” mode) is 150 passes in the number of print passes, and the high-level print quality level (“clean” mode). ) Is 100 passes in terms of the number of print passes, but the check timing may be a fixed number of print passes (for example, 100 passes) regardless of the print quality level. When the print quality level is low, printing is performed with large dots and the movement amount in one transport direction is large. On the other hand, when the print quality level is high, printing is performed with small dots and transported once. The amount of movement in the direction is small. For this reason, the number of print passes when printing the same print data is larger when the print quality level is high than when the print quality level is low. As a result, even if the inspection timing is a fixed number of printing passes, the inspection frequency when printing the same print data is higher when the print quality level is high. Therefore, the nozzle inspection can be executed at an appropriate frequency according to the print quality level. For the same reason, the inspection timing may be set to a fixed number of ink ejections (for example, 10,000 times) regardless of the print quality level, instead of FIG. 13 of the second embodiment.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

1 is a configuration diagram showing an outline of the configuration of an inkjet printer according to a first embodiment. Explanatory drawing of the print head of 1st Embodiment. Explanatory drawing of the paper feed mechanism of 1st Embodiment. The block diagram which shows the outline of a structure of the nozzle test | inspection apparatus of 1st Embodiment. The flowchart of the main routine of 1st Embodiment. Explanatory drawing of the inspection timing corresponding | compatible table of 1st Embodiment. 6 is a flowchart of a print processing routine according to the first embodiment. The flowchart of the nozzle test | inspection routine of 1st Embodiment. Explanatory drawing of the test | inspection position in the nozzle test | inspection process of 1st Embodiment. Explanatory drawing of the principle which an induced voltage produces by the electrostatic induction of 1st Embodiment. Explanatory drawing which shows an example of the threshold value Vthr of 1st Embodiment. The flowchart of the main routine of 2nd Embodiment. Explanatory drawing of the inspection timing corresponding | compatible table of 2nd Embodiment. 10 is a flowchart of a print processing routine according to the second embodiment. The flowchart of the nozzle test routine of 2nd Embodiment. The flowchart of the main routine of 3rd Embodiment. 10 is a flowchart of a print processing routine according to a third embodiment. The flowchart of the nozzle test routine of 3rd Embodiment. The flowchart of the main routine of other embodiment. The flowchart of the main routine of other embodiment. Explanatory drawing of the inspection timing corresponding | compatible table of other embodiment. Explanatory drawing of the inspection timing corresponding | compatible table of other embodiment. Explanatory drawing of the nozzle test | inspection apparatus of other embodiment.

Explanation of symbols

14 Paper feed tray, 18 Recording paper insertion slot, 20 Inkjet printer, 21 Printer mechanism, 22 Carriage, 23, 23Y, 23M, 23C, 23K Nozzle, 24 Print head, 25 Linear encoder, 26 Ink cartridge, 28 Guide, 31 Paper feed mechanism, 32 Carriage belt, 33 Drive motor, 34 Carriage motor, 35 Paper feed roller, 36 Paper feed roller, 37 Paper discharge roller, 40 Cap device, 43, 43Y, 43M, 43C, 43K Nozzle array, 44 Platen, 47 mask circuit, 48 piezoelectric element, 50 nozzle inspection device, 51 inspection box, 52 inspection area, 53 voltage application circuit, 54 voltage detection circuit, 54a integration circuit, 54b inversion amplification circuit, 54c A / D conversion circuit, 55 upper ink Absorber, 56 bottom Side ink absorber, 57 electrode member, 70 controller, 72 CPU, 73 ROM, 74 RAM, 75 flash memory, 79 interface (I / F), 102 light emitting element, 104 light receiving element.

Claims (4)

An inkjet printer comprising a print head having a plurality of nozzles for discharging a print recording liquid, and performing printing on a print medium while moving the print head for each pass,
Detection means capable of detecting that the printing recording liquid is actually discharged from each nozzle of the print head;
Cleaning means for performing head cleaning of the print head;
Inspection timing setting means for setting the inspection timing;
When the inspection timing is reached, a nozzle inspection is performed based on whether or not the detection means has detected that the printing recording liquid is actually ejected from the nozzle, and an abnormal nozzle exists due to the nozzle inspection. Control means for controlling the cleaning means to perform head cleaning of the print head and performing the nozzle inspection after the head cleaning ;
With
The inspection timing setting means includes
When the abnormality is eliminated by the N-th head cleaning (N is a positive integer) by the cleaning means, the first pass number is set as the inspection timing when the print quality level is low, and when the print quality level is high, the first time is set. A second pass number smaller than the first pass number is set as the inspection timing ;
When the abnormality is eliminated by the (N + 1) -th head cleaning by the cleaning means, when the print quality level is low, a third pass number larger than the first pass number is set as the inspection timing, and the print quality level is set. An inkjet printer characterized in that when the value is high, a fourth pass number that is greater than the second pass number and less than the third pass number is set as the inspection timing . The cleaning means is a means for forcibly suctioning each nozzle of the print head with a preset suction force among multi-stage suction forces to perform head cleaning,
The inspection timing setting means sets a small number of passes to the inspection timing so that the inspection timing comes earlier as the set suction force is smaller.
The inkjet printer according to claim 1 . A print head having a plurality of nozzles for discharging the print recording liquid, a detection means capable of detecting that the print recording liquid is actually discharged from each nozzle of the print head, and a cleaning means for performing head cleaning of the print head A nozzle inspection method in an ink jet printer that performs printing on a print medium while moving the print head for each pass,
(A) setting inspection timing;
(B) When the inspection timing is reached, a nozzle inspection is performed based on whether or not the detection means has detected that the printing recording liquid has actually been ejected from the nozzle. Controlling the cleaning means to perform head cleaning of the print head when present and performing the nozzle inspection after the head cleaning ;
Including
The step (a)
When the abnormality is eliminated by the N-th head cleaning (N is a positive integer) by the cleaning means, the first pass number is set as the inspection timing when the print quality level is low, and when the print quality level is high, the first time is set. A second pass number smaller than the first pass number is set as the inspection timing ;
When the abnormality is eliminated by the (N + 1) -th head cleaning by the cleaning means, when the print quality level is low, a third pass number larger than the first pass number is set as the inspection timing, and the print quality level is set. A nozzle inspection method characterized by setting a fourth pass number that is greater than the second pass number and less than the third pass number when the inspection time is high. A program for causing one or more computers to execute each step of the nozzle inspection method according to claim 3 .

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