JP4752418B2 - Inkjet printer - Google Patents

Description

  The present invention relates to an ink jet printer, and more particularly to an ink jet printer capable of inspecting a print head having a plurality of ejection holes for ejecting a print recording liquid.

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, and is generated by the ejection of the ink droplet. A device that inspects whether or not an ink droplet is ejected from a nozzle by detecting an induced voltage is known (for example, see Patent Document 1).
JP 59-120464 A

  In this type of ink jet printer, when the inspection of whether or not ink droplets are ejected from the nozzles is repeated, ink deposits accumulate in the inspection area. On the other hand, during normal printing, an ink mist called satellite moves together with ink droplets, so that ink deposits also accumulate on the platen. Here, if the ink deposit accumulated in the inspection area is connected to the ink deposit on the platen, the following problems occur. That is, when inspecting whether or not an ink droplet is ejected from a nozzle, a predetermined potential difference is generated between the inspection area and the print head, but the ink deposit is generally conductive. Therefore, the ink deposit accumulated in the inspection region and the ink deposit on the platen are at the same potential, and a predetermined potential difference may not occur between the inspection region and the print head. In particular, this problem becomes serious when the platen is connected to the mechanical frame and is grounded.

  The present invention has been made to solve such problems, and an object of the present invention is to provide an ink jet printer that can reliably generate a predetermined potential difference between an inspection region and a print head.

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

The inkjet printer of the present invention is
An inkjet printer capable of inspecting a print head having a plurality of ejection holes for ejecting a print recording liquid,
An inspection area where the printing recording liquid discharged from the discharge hole can reach,
Print head driving means for discharging the printing recording liquid from the discharge holes;
An electrical change means for detecting an electrical change in the inspection area;
For each discharge hole of the print head, the print head drive unit is controlled in a state where a predetermined potential difference is generated between the inspection area and the print head and the print recording liquid before discharge is charged, and the print recording is performed. An inspection control means for performing a head inspection as to whether or not to normally discharge the print recording liquid, based on a detection result of the electrical change detection means when the liquid is discharged to the inspection area;
A print breaker portion formed so that the print recording liquid deposit accumulated in the inspection area and the print recording liquid deposit accumulated around the inspection area are discontinuous;
It is equipped with.

  In this ink jet printer, for each discharge hole of the print head, a predetermined potential difference is generated between the inspection area and the print head, and the print recording liquid is discharged to the inspection area in a state where the print recording liquid before discharge is charged. Based on the electrical change between the inspection area and the print head at this time, a head inspection is performed to determine whether or not the print recording liquid is normally discharged. Further, the print recording liquid deposit is accumulated in the inspection area by performing the head inspection, and the print recording liquid deposit is also accumulated around the inspection area due to ink mist or the like by executing printing on the print medium. However, since the print recording liquid deposit deposited in the inspection area and the print recording liquid deposit deposited around the inspection area are discontinuous due to the deposit disconnection portion, both are electrically insulated. For this reason, when a voltage is applied to the inspection area print head, the voltage does not leak from the periphery of the inspection area. Therefore, it is possible to reliably generate a predetermined potential difference with the inspection area print head.

  In the ink jet printer of the present invention, the deposit disconnection portion may be an outer peripheral groove formed around the inspection region. By doing so, the print recording liquid deposit accumulated in the inspection area and the print recording liquid deposit accumulated around the inspection area are separated by the outer circumferential groove and become discontinuous.

  In the ink jet printer of the present invention, when the deposit disconnection portion is an outer peripheral groove, at least one of the wall on the inspection area side and the wall on the opposite side to the inspection area forming the outer peripheral groove is formed substantially vertically. It is preferable. That is, it is preferable that at least one of the walls on both sides of the outer circumferential groove is substantially vertical. In this way, since the printing recording liquid does not easily accumulate on the substantially vertical wall, the printing recording liquid deposit accumulated in the inspection area and the printing recording liquid accumulation accumulated around the inspection area are divided by the substantially vertical wall. Become discontinuous.

  In the ink jet printer according to the aspect of the invention, when the deposit breaking portion is an outer peripheral groove, at least one of the wall on the inspection area side and the wall on the opposite side to the inspection area forming the outer peripheral groove is substantially horizontal toward the other. You may have the eaves part which extended. Since the print recording liquid does not easily accumulate on the back side of the collar portion, the print recording liquid deposit accumulated in the inspection area and the print recording liquid deposit accumulated around the inspection area are divided by the collar and become discontinuous. In particular, when the printing recording liquid is a pigment ink, it is preferable to adopt this structure because even a substantially vertical wall may be deposited.

  In the ink jet printer of the present invention, when the deposit disconnection portion is an outer peripheral groove, at least one of the wall on the inspection region side and the wall opposite to the inspection region forming the outer peripheral groove is in the space of the outer peripheral groove. You may have the folding | turning part folded back | folded so that it may make a U-turn. Since the print recording liquid does not easily accumulate on the back side of the folded portion, the print recording liquid deposit accumulated in the inspection area and the print recording liquid deposit accumulated around the inspection area are separated by the folded portion and become discontinuous. In particular, when the printing recording liquid is a pigment ink, it is preferable to adopt this structure because even a substantially vertical wall may be deposited.

  In the ink jet printer of the present invention, when the deposit disconnection portion is an outer peripheral groove, the upper end surface of at least one of the wall on the inspection region side and the wall opposite to the inspection region which forms the outer peripheral groove is an inclined surface. It is preferable. Since the print recording liquid does not easily accumulate on the inclined surface, the print recording liquid deposit accumulated in the inspection area and the print recording liquid deposit accumulated around the inspection area are separated by the inclined surface and become discontinuous.

  In the ink jet printer of the present invention, when the deposit disconnection portion is an outer peripheral groove, at least one of the wall on the inspection region side and the wall opposite to the inspection region which forms the outer peripheral groove has water repellency. It is preferable. In general, since the printing recording liquid contains water, it is difficult for the printing recording liquid to accumulate on the water-repellent wall, and the printing recording liquid deposit accumulated in the inspection area and the printing recording liquid accumulation accumulated around the inspection area. Objects are separated by this water-repellent wall and become discontinuous.

  FIG. 1 is a configuration diagram showing an outline of the configuration of an inkjet printer 20 according to an embodiment of the present invention, 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 print head inspection apparatus 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 near the right end of the platen 44, a print head inspection device 50 formed near the left end on the platen 44 and inspecting whether or not 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).

  The print head inspection device 50 forms the core of the present invention. As shown in FIG. 4, the print head inspection device 50 is provided in an inspection box 51 in which ink droplets flying from the nozzles 23 of the print head 24 can land. 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 of the inspection area 52 are detected. And a voltage detection circuit 54. Here, the voltage application circuit 53 has a switch SW for opening and closing the circuit, and this switch SW is turned on when a head inspection routine described later is executed, but is turned off in other cases.

  The inspection box 51 is provided at a position deviated to the left from the printable area of the platen 44 (see FIG. 1), is a substantially rectangular parallelepiped housing with an upper opening, and is made of water-repellent material made of silicon rubber or fluororesin It is. An outer peripheral groove 81 is formed around the inspection box 51. Of the walls 82 and 83 on both sides of the outer peripheral groove 81, the wall 82 on the inspection box 51 side is a substantially vertical wall, and the wall 83 on the opposite side to the inspection box 51 has a depression 84 in the middle, and is above the depression 84. Is formed with a folded portion 85 which is folded so as to make a U-turn in the inner space of the outer peripheral groove 81. The folded portion 85 is also made of silicon rubber or fluororesin, which is a water repellent material. 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 direct current power source (for example, 400 V) and a resistance element (for example, 1 MΩ) 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 the ink clogging of the nozzle is detected by the print head inspection device 50, a negative pressure of the suction pump is applied to the nozzle formation surface of the print head 24 sealed by the cap device 40 as necessary. The ink clogged from the nozzle 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 head 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. A voltage signal output from the voltage detection circuit 54 of the print head inspection apparatus 50, a position signal from the linear encoder 25, and the like are input to the controller 70 via an input port (not shown) and output from the user PC 10. The printed print job 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 print data waiting to be printed (step S100). Here, the print data received from the user PC 10 is stored in the print buffer area formed in the RAM 74 and becomes print data waiting to be printed. Therefore, when the print data is received, it is printed immediately as well as when printing is in progress. Even if possible, the print data is in a print waiting state. If there is no print data waiting for printing in step S100, the main routine is terminated. On the other hand, if there is print data waiting for printing in step S100, a head inspection routine is executed (step S110).

  This head inspection routine is a process for inspecting whether all the nozzles 23 arranged in the print head 24 are clogged. FIG. 6 is a flowchart of this head inspection routine. When this routine is started, the CPU 72 turns on the switch SW of the voltage application circuit 53 to generate a predetermined potential difference between the inspection area 52 and the print head 24, and at the same time the ink is supplied from the inspection position, that is, the nozzle 23. The position of the inspection area 52 to be ejected is acquired (step S300). Here, since the solid matter contained in the ink may be deposited on the surface of the inspection region 52 due to the ejection of the ink, the inspection position is set to be changed every time the head inspection is performed. FIG. 7 is an explanatory diagram of the inspection position in the print head inspection process. In FIG. 7, a plurality of inspection positions p1, p2, p3, and p4 are set. In one head inspection, each nozzle row 43 is the same so that variations in the detected value of the dielectric voltage due to the difference in inspection position do not occur. It is set to eject ink to the inspection position. For example, when this head 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 head inspection is performed at the inspection position p1, the next head inspection is performed at the inspection position p2. Returning to FIG. 6, after acquiring the current inspection position in step S <b> 300, the CPU 72 drives the carriage motor 34 so that the nozzle array 43 to be inspected among the nozzle arrays 43 of the print head 24 is set to 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. 8 is an explanatory diagram of the principle that an induced voltage is generated by electrostatic induction. As shown in FIG. 8A, 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. 8B, 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. 8C, 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. 6, the CPU 72 discharges the charged ink droplet 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. 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. 9, this 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 arrays 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 head 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 above-described head inspection routine (step S110), it is determined whether or not there is a nozzle 23 in which an abnormality has occurred among all the nozzles 23 arranged in the print head 24. Judgment is made based on the content stored in a predetermined area of the RAM 74 (step S120), and when there is a nozzle 23 in which an abnormality has occurred, the print head 24 is cleaned in consideration of clogging. It is determined whether the number of cleanings performed before that is less than a predetermined number (for example, three times) (step S130). When the number of cleanings is less than the predetermined number, the print head 24 is cleaned (step S140). 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 S110 again to check whether the abnormality of the nozzle 23 has been eliminated. In this step S130, only the nozzle 23 in which an abnormality has occurred may be re-inspected, 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, if the number of cleanings performed in step S130 is equal to or greater than the predetermined 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 S150 ) This main routine is terminated.

  On the other hand, if there is no abnormal nozzle 23 in step S120, a print processing routine is executed (step S160). This print processing routine is a process for printing the print data as shown in FIG. Here, “bidirectional printing” will be described as an example. When this routine is started, the CPU 72 first executes a paper feed process (step S400). 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. 4). 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 S410). . Subsequently, the CPU 72 determines whether or not there is print data to be printed on the recording paper S currently being printed (step S420). A conveyance process for rotating the roller 35 and conveying the recording sheet S by a predetermined amount is executed (step S430), 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 S440). Subsequently, the CPU 72 determines whether or not there is print data to be printed on the recording paper S currently being printed (step S450). A conveyance process for rotating the roller 35 to convey the recording paper S by a predetermined amount is executed (step S460), and the processes of steps S410 to S450 are executed. On the other hand, when there is no print data to be printed on the recording paper S that is currently being printed in step S420 or step S450, the CPU 72 executes a paper discharge process for discharging the recording paper S (step S470). 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 S470, the CPU 72 determines whether or not there is a next page to be printed (step S480). When there is a next page to be printed, the processing of steps S400 to S470 is executed to print the page. When there is no next page, this print processing routine is terminated. Also, the main routine of FIG. 5 ends after this print processing routine ends.

  Here, the state of the inspection area 52 and its surroundings after repeatedly executing the main routine will be described with reference to FIG. FIG. 11 is an explanatory diagram of the state of the inspection area 52 and its surroundings. When the main routine is repeatedly executed, the head inspection routine and the print processing routine are repeatedly executed accordingly. When the head inspection routine is repeated, ink droplets are ejected many times to the inspection region 52. Therefore, the ink once absorbed by the upper ink absorber 55 initially passes through the gap between the grid-like electrode members 57. What has been absorbed and held in the lower ink absorber 56 through the ink gradually accumulates on the surface of the upper ink absorber 55, and the ink deposit 90 accumulates in the inspection region 52. . In addition, when the print processing routine is repeatedly executed, ink mist called satellite is scattered along with ink droplets, so that nothing originally adhered on the platen 44 is gradually printed on the platen 44. Since the ink mist adheres to the area not covered with the paper and dries and accumulates, the ink deposit 92 also accumulates around the inspection area 52 in the platen 44. Here, the platen 44 is grounded via a mechanical frame 80 (see FIG. 1) of the inkjet printer 20. In addition, since both the ink deposits 90 and 92 are conductive, if the two ink deposits 90 and 92 are connected, the potential of the inspection region 52 coincides with the ground potential. When the switch SW of the voltage application circuit 53 is turned on in the routine, the voltage leaks, and a predetermined potential difference cannot be generated between the inspection area 52 and the print head 24. However, in the present embodiment, an outer peripheral groove 81 is formed around the inspection box 51, and the wall 82 on the inspection box 51 side among the walls 82 and 83 on both sides of the outer peripheral groove 81 is a substantially vertical wall with water repellency, The wall 83 opposite to the inspection box 51 has a recess 84 in the middle, and a water repellent folded portion 85 is formed above the recess 84 so as to be folded back into the inner space of the outer peripheral groove 81. . For this reason, even if the pigment ink has poor fluidity as compared with the dye ink, the ink does not accumulate at least on the back side 85a of the folded portion 85. Therefore, the ink deposit 90 in the inspection region 52 and the ink deposit 92 on the platen 44 around the inspection region 52 are discontinuous at least on the back side 85a of the folded portion 85, and are electrically insulated. Note that ink does not easily accumulate on the back wall 83a of the folded portion 85, and ink does not easily accumulate on the vertical wall 82 on the inspection box 51 side if the ink accumulation amount is small. For this reason, the ink deposits 90 and 92 can be discontinuous even in these portions. Further, the groove width of the outer peripheral groove 81, the size of the folded portion 85, and the like may be appropriately determined in consideration of the ink accumulation amount and strength.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. The inspection area 52 of this embodiment corresponds to the inspection area of the present invention, the mask circuit 47 and the piezoelectric element 48 correspond to the print head driving means, the voltage detection circuit 54 corresponds to the electrical change detection means, and the CPU 72 performs the inspection. It corresponds to the control means, and the outer circumferential groove 81 (particularly, the folded portion 85) corresponds to the deposit disconnection portion. Further, the pigment ink of the present embodiment corresponds to the printing recording liquid of the present invention, the nozzle 23 corresponds to the discharge hole, and the voltage application circuit 53 corresponds to the potential difference generating means.

  According to the inkjet printer 20 of the present embodiment described in detail above, the ink deposit 90 in the inspection region 52 and the ink deposit 92 on the platen 44 around the inspection region 52 are discontinuous at least on the back side 85a of the folded portion 85. Therefore, the voltage is not leaked when the switch SW of the voltage application circuit 53 is turned on, and a predetermined potential difference is reliably established between the inspection region 52 and the print head 24. Can be generated. Therefore, the head inspection routine can be stably performed over a long period of time.

  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.

  For example, instead of the structure around the inspection box 51 of the above-described embodiment, the structure of FIG. 12 may be adopted. The structure of FIG. 12 is the same structure as that of the above-described embodiment except that the upper end surface of the vertical wall 82 on the inspection box 51 side is an inclined surface (a surface inclined downward toward the outside). For this reason, the same components are denoted by the same reference numerals and the description thereof is omitted. According to this structure, in addition to the effects of the above-described embodiment, the ink is also difficult to deposit on the upper end surface of the wall 82. Therefore, the ink deposit 90 in the inspection region 52 and the ink deposit around the inspection region 52 are provided. 92 may be discontinuous even at the upper end surface of the wall 82.

  Alternatively, the structure shown in FIG. 13 may be adopted instead of the structure around the inspection box 51 of the above-described embodiment. The structure shown in FIG. 13 is the same as the structure shown in FIG. 13 except that a hook 86 extending horizontally from the wall 83 (back wall 83a) opposite to the inspection box 51 toward the inspection box 51 is formed instead of the folded portion 85. The structure is the same as that of the embodiment described above. For this reason, the same components are denoted by the same reference numerals and the description thereof is omitted. According to this structure, ink hardly accumulates at least on the back side 86 a of the flange 86, so that the ink deposit 90 in the inspection region 52 and the ink deposit 92 on the platen 44 around the inspection region 52 are separated from each other. At least the back side 86a of the flange 86 is discontinuous and is electrically insulated. Therefore, the same effect as the above-described embodiment can be obtained.

  Alternatively, the structure shown in FIG. 14 may be adopted instead of the structure around the inspection box 51 of the above-described embodiment. In the structure of FIG. 14, an outer peripheral groove 181 is formed around the inspection box 51, and a wall 183 opposite to the inspection box 51 among the walls 182 and 183 on both sides of the outer peripheral groove 181 is a substantially vertical wall. The side wall 182 is formed with a folded portion 185 folded at the upper end so as to make a U-turn in the inner space of the outer peripheral groove 181. Therefore, as in the above-described embodiment, ink is not deposited at least on the back side 185 a of the folded portion 185, and the ink deposit 90 on the inspection region 52 and the ink deposit 92 on the platen 44 around the inspection region 52. Is discontinuous at least on the back side 185a of the folded portion 185 and is electrically insulated. Therefore, the same effect as the above-described embodiment can be obtained.

  Alternatively, the structure shown in FIG. 15 may be adopted instead of the structure around the inspection box 51 of the above-described embodiment. In the structure of FIG. 15, an outer peripheral groove 281 is formed around the inspection box 51, and both walls 282 and 283 on both sides of the outer peripheral groove 281 are formed substantially vertically. This structure is not so suitable when pigment ink is used because the ink deposits on the substantially vertical walls 282 and 283 relatively early, but when using dye ink, it flows less than pigment ink. Due to its high nature, it is difficult for ink to deposit on the substantially vertical walls 282 and 283. For this reason, when dye ink is used, the ink deposit 90 in the inspection region 52 and the ink deposit 92 on the platen 44 around the inspection region 52 become discontinuous at the walls 282 and 283 of the outer circumferential groove 281 and become electrically Insulatively. Therefore, the voltage does not leak when the switch SW of the voltage application circuit 53 is turned on, and a predetermined potential difference can be reliably generated between the inspection region 52 and the print head 24. Of course, when dye ink is used, the structure shown in FIGS.

  In the above-described embodiment, the inspection box 51 and the folded portion 85 are made of a water-repellent material. However, if the structure shown in FIG. The effect of the embodiment can be obtained. However, in order to obtain a more remarkable effect, it is preferable to use a water repellent material as in the above-described embodiment. This also applies to the structures of FIGS.

1 is a configuration diagram illustrating an outline of a configuration of an inkjet printer 20. 2 is an explanatory diagram of a print head 24. FIG. 3 is an explanatory diagram of a paper feeding mechanism 31. FIG. 2 is a configuration diagram showing an outline of a configuration of a print head inspection apparatus 50. FIG. It is a flowchart of a main routine. It is a flowchart of a head inspection routine. It is explanatory drawing of the test | inspection position in a head test | inspection process. It is explanatory drawing of the principle which an induced voltage produces by electrostatic induction. It is explanatory drawing which shows an example of threshold value Vthr. It is a flowchart of a printing process routine. It is explanatory drawing of the test | inspection area | region 52 and the surrounding condition. It is explanatory drawing of the test | inspection area | region 52 and the surrounding condition. It is explanatory drawing of the test | inspection area | region 52 and the surrounding condition. It is explanatory drawing of the test | inspection area | region 52 and the surrounding condition. It is explanatory drawing of the test | inspection area | region 52 and the surrounding condition.

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 print head inspection device, 51 inspection box, 52 inspection area, 53 voltage application circuit, 54 voltage detection circuit, 54a integration circuit, 54b inverting amplification circuit, 54c A / D conversion circuit, 55 upper side Ink absorber, 5 Lower ink absorber, 57 electrode member, 70 controller, 72 CPU, 73 ROM, 74 RAM, 75 flash memory, 79 interface (I / F), 80 mechanical frame, 81 outer peripheral groove, 82 wall, 83 wall, 83a back Wall, 84 depression, 85 folded portion, 85a back side of folded portion, 86 collar, 86a back side of collar, 90 ink deposit, 92 ink deposit.

Claims (6)

An inkjet printer capable of inspecting a print head having a plurality of ejection holes for ejecting a print recording liquid,
An inspection area where the printing recording liquid discharged from the discharge hole can reach,
Print head driving means for discharging the printing recording liquid from the discharge holes;
An electrical change detecting means for detecting an electrical change in the inspection area;
For each discharge hole of the print head, the print head drive unit is controlled in a state where a predetermined potential difference is generated between the inspection area and the print head and the print recording liquid before discharge is charged, and the print recording is performed. An inspection control means for performing a head inspection as to whether or not to normally discharge the print recording liquid, based on a detection result of the electrical change detection means when the liquid is discharged to the inspection area;
A print breaker portion formed so that the print recording liquid deposit accumulated in the inspection area and the print recording liquid deposit accumulated around the inspection area are discontinuous;
With
The deposit disconnection portion is an outer peripheral groove formed around the inspection region,
At least one of the wall on the inspection region side and the wall on the opposite side of the inspection region forming the outer circumferential groove has a flange extending substantially horizontally toward the other,
Inkjet printer. An inkjet printer capable of inspecting a print head having a plurality of ejection holes for ejecting a print recording liquid,
An inspection area where the printing recording liquid discharged from the discharge hole can reach,
Print head driving means for discharging the printing recording liquid from the discharge holes;
An electrical change detecting means for detecting an electrical change in the inspection area;
For each discharge hole of the print head, the print head drive unit is controlled in a state where a predetermined potential difference is generated between the inspection area and the print head and the print recording liquid before discharge is charged, and the print recording is performed. An inspection control means for performing a head inspection as to whether or not to normally discharge the print recording liquid, based on a detection result of the electrical change detection means when the liquid is discharged to the inspection area;
A print breaker portion formed so that the print recording liquid deposit accumulated in the inspection area and the print recording liquid deposit accumulated around the inspection area are discontinuous;
With
The deposit disconnection portion is an outer peripheral groove formed around the inspection region,
At least one of the wall on the inspection region side forming the outer peripheral groove and the wall on the opposite side of the inspection region has a folded portion that is folded back so as to make a U-turn in the space of the outer peripheral groove.
Inkjet printer. At least one of the wall on the inspection region side and the wall on the opposite side of the inspection region forming the outer circumferential groove is formed substantially vertically;
The ink jet printer according to claim 1 . The printing recording liquid is a pigment ink.
The ink jet printer according to claim 1. The upper end surface of at least one of the wall on the inspection region side forming the outer peripheral groove and the wall on the opposite side of the inspection region is an inclined surface,
The ink jet printer according to claim 1. At least one of the wall on the inspection area side and the wall on the opposite side of the inspection area forming the outer circumferential groove has water repellency,
The ink jet printer according to claim 1.

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