JP2010194795A - Fluid ejecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid extension of time necessary for inspecting a nozzle and time necessary for forming an image. <P>SOLUTION: A platen gap corresponding to the kind of a printing medium is read out from a RAM before image formation. A head height adjusting mechanism 80 is controlled so that the height from a platen 29 to a printing head 24 becomes equal to the read platen gap PG. Simultaneously with the control, or before and after the control, a target value of the height of a flash box 40 is calculated on the basis of a predetermined sensor gap and the platen gap PG read out from the RAM, and an FB height adjusting mechanism 44 is controlled to make the height of the flash box 40 the target value. Consequently, even when the timing of executing nozzle inspection comes thereafter, an interval between the printing head 24 and the flash box 40 has already becomes equal to the predetermined sensor gap, and nozzle inspection can be carried out immediately. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fluid ejection device.

  Conventionally, inkjet printers that detect voltage changes caused by ejecting charged ink droplets from the nozzles of the print head to the ink receiving area and inspect whether the ink is ejected normally from the nozzles have been proposed Has been. In such an ink jet printer, a plurality of nozzle rows are formed in a print head, and the plurality of nozzle rows are sequentially set as inspection target nozzle rows, and a plurality of nozzles constituting the set inspection target nozzle rows are sequentially set as inspection target nozzles. The nozzle inspection is executed for the set inspection target nozzle. In this type of inkjet printer, in order to prevent ink deposits from accumulating in the ink receiving area and short-circuiting between the ink receiving area and the print head via the ink deposit, the ink receiving area can be raised and lowered. It has been proposed that the print head can be moved up and down (see Patent Document 1).

  By the way, the mechanism capable of moving the print head up and down is also used when adjusting the gap (platen gap) between the print head and the platen that supports the paper conveyed from below to the position facing the print head (patent). Reference 2). Specifically, for example, when the platen gap is always the same, when the paper to be printed is thick paper such as an envelope as compared to plain paper, the gap between the paper and the print head is narrowed, causing problems such as uneven density. Therefore, the platen gap is adjusted according to the thickness of the paper.

JP 2007-98642 A (paragraph 0056 etc.) JP 2004-314591 A (FIG. 6 etc.)

  Now, when performing the above-described nozzle inspection, if the interval between the print head and the ink receiving area is not narrowed, even if ink is ejected from the nozzles, a sufficient voltage change will not occur, which is abnormal despite being normal. It may be judged. For this reason, for example, when thick paper is used in printing before the nozzle inspection is performed and the platen gap is set wide, the print head is lowered before the inspection to narrow the interval between the print head and the ink receiving area. There was a need to do.

  However, if the print head is lowered before the nozzle inspection in this way, there is a problem that the total time required for the nozzle inspection becomes longer. In particular, when the nozzle inspection timing comes in the middle of printing on thick paper, after the print head is lowered to narrow the gap with the ink area and nozzle inspection is performed, before printing on thick paper is resumed. In addition, the print head must be raised again to widen the platen gap, resulting in an increase in the total time required for printing.

  The present invention has been made in view of the above-described problems, and a main object thereof is to prevent the time required for nozzle inspection and the time required for image formation from being prolonged.

  The fluid ejection device of the present invention employs the following means in order to achieve the main object described above.

The first fluid ejection device of the present invention comprises:
A head having a plurality of nozzles and discharging fluid toward a target conveyed on the platen from the nozzles while moving in the main scanning direction;
An inspection region that is provided at a position that can face the head, and that receives fluid ejected from the nozzle of the head when performing nozzle inspection;
A head height adjusting means for adjusting the height of the head;
Inspection area height adjusting means for adjusting the height of the inspection area;
Storage means for storing fluid discharge conditions in association with a platen gap indicating a height from the platen to the head;
Fluid discharge condition input means for inputting fluid discharge conditions;
A platen gap reading means for reading a platen gap corresponding to the fluid discharge condition input by the fluid discharge condition input means from the storage means;
Head height control means for controlling the head height adjusting means so that the height from the platen to the head becomes the platen gap read from the storage means;
In parallel with or before and after adjusting the height from the platen to the head by controlling the head height adjusting means, based on the predetermined sensor gap and the platen gap read from the storage means An inspection area height control means for calculating a target value of the height of the inspection area and controlling the inspection area height adjusting means so that the height of the inspection area becomes the target value;
It is equipped with.

  In this fluid ejection device, the platen gap corresponding to the fluid ejection condition input by the fluid ejection condition input unit is read from the storage unit. Then, the head height adjusting means is controlled so that the height from the platen to the head becomes the read platen gap. In parallel with or before or after this control, a target value for the height of the inspection area is calculated based on a predetermined sensor gap and the platen gap read from the storage means, and the height of the inspection area becomes the target value. The inspection area height adjusting means is controlled. By doing so, even if the timing for performing the nozzle inspection thereafter comes, the interval between the head and the inspection area has already become a predetermined sensor gap, so that the nozzle inspection can be performed immediately. Therefore, it is possible to prevent the time required for the nozzle inspection from being prolonged.

  Here, the “fluid ejection condition” refers to a condition related to the platen gap, such as the thickness of the target, the image resolution when forming an image, and the ambient temperature. “Nozzle inspection” refers to nozzle inspection in which the distance between the inspection region and the head affects the accuracy.

The second fluid ejection device of the present invention comprises:
A head having a plurality of nozzles and discharging fluid toward a target conveyed on the platen from the nozzles while moving in the main scanning direction;
An inspection region that is provided at a position that can face the head, and that receives fluid ejected from the nozzle of the head when performing nozzle inspection;
A head height adjusting means for adjusting the height of the head;
Inspection area height adjusting means for adjusting the height of the inspection area;
Storage means for storing fluid discharge conditions in association with a platen gap indicating a height from the platen to the head;
Fluid discharge condition input means for inputting fluid discharge conditions;
Image data input means for inputting image data;
A platen gap reading means for reading a platen gap corresponding to the fluid discharge condition input by the fluid discharge condition input means from the storage means;
Before executing the image forming process based on the image data input by the image data input means, the head height adjusting means is set so that the height from the platen to the head becomes the platen gap read from the storage means. A head height control means to control;
Image formation processing means for controlling the head so that an image based on the image data input by the image data input means is formed on the target;
When the timing of the nozzle inspection comes before or during execution of image formation by the image forming processing means, a predetermined sensor gap and a platen gap read from the storage means without controlling the head height adjusting means A target value of the height of the inspection area based on the inspection area height control means for controlling the inspection area height adjustment means so that the height of the inspection area becomes the target value;
It is equipped with.

  In this fluid ejection device, the platen gap corresponding to the fluid ejection condition input by the fluid ejection condition input unit is read from the storage unit. Further, before executing the image forming process based on the image data input by the image data input means, the head height adjusting means is controlled so that the height from the platen to the head becomes the platen gap read from the storage means, Thereafter, the head is controlled so that an image based on the image data input by the image data input means is formed on the target. Then, when the timing of nozzle inspection comes before or during execution of image formation, it is possible to control the inspection area based on the predetermined sensor gap and the platen gap read from the storage means without controlling the head height adjusting means. A target value of the height is calculated, and the inspection area height adjusting means is controlled so that the height of the inspection area becomes the target value. By doing so, even if the timing of nozzle inspection comes before or during execution of the image forming process, the nozzle inspection can be executed without changing the platen gap. Therefore, it is not necessary to change the platen gap before starting or restarting image formation after the nozzle inspection is completed, and it is possible to prevent the time required for image formation from being prolonged.

  In the first and second fluid ejection devices of the present invention, the nozzle inspection is a state in which a predetermined voltage is applied between the head and the inspection region with the gap between the head and the inspection region as the sensor gap. Thus, an inspection may be performed to determine whether each nozzle is normal or abnormal based on an electrical change between the head and the inspection region when the head is controlled so that fluid is ejected from each nozzle of the head. In this case, if the distance between the head and the inspection area is too wide, the sensitivity may be lowered and erroneous determination may be caused. It is preferable to set the distance to an appropriate distance, and therefore, the significance of applying the present invention is high. . In addition to the nozzle inspection, a light emitting element and a light receiving element are installed in the inspection area, and the print head is placed at a position where the light emitted from the light emitting element and incident on the light receiving element intersects the fluid discharged from the nozzle. It is also possible to employ an arrangement that determines whether the nozzle is normal or abnormal based on whether or not the light is blocked by the fluid based on the output signal of the light receiving element after operating so that the fluid is discharged from the nozzle. In this case, if the distance between the head and the inspection area is too wide, the fluid discharged from the nozzle may be bent or diffused, resulting in erroneous determination. It is preferable to set the distance to an appropriate distance. The significance of applying the present invention is high.

  In the first and second fluid ejection devices according to the present invention, the nozzle inspection includes a light emitting element and a light receiving element installed in the inspection region, light emitted from the light emitting element and incident on the light receiving element, and the nozzle. Each of the print heads is arranged at a position where the fluid to be ejected intersects, and after each fluid is ejected from each nozzle, each of the print heads depends on whether light is blocked by the fluid based on the output signal of the light receiving element. It is good also as an inspection which judges normality / abnormality of a nozzle. In this case, if the distance between the head and the inspection area is too wide, the fluid discharged from the nozzle may be bent or diffused, resulting in erroneous determination. It is preferable to set the distance to an appropriate distance. The significance of applying the present invention is high.

FIG. 2 is a configuration diagram illustrating an example of a schematic configuration of a printer 20. FIG. 3 is a block diagram showing electrical connection of a print head 24. 4 is an explanatory diagram of a head height adjustment mechanism 80. FIG. FIG. 2 is a block diagram showing an outline of the configuration of a nozzle inspection device 50. Explanatory drawing of FL height adjustment mechanism. The flowchart of a main routine. The flowchart of a nozzle test routine. Explanatory drawing showing a mode in case a platen gap differs. The flowchart of a main routine. The flowchart of a test | inspection monitoring routine. Explanatory drawing of the nozzle test | inspection using light. Explanatory drawing which shows the example of arrangement | positioning of another electrode member.

  Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram illustrating an example of a schematic configuration of the printer 20 according to the present embodiment, FIG. 2 is a block diagram illustrating electrical connection of the print head 24, and FIG. 3 is a head height adjustment. FIG. 4 is an explanatory diagram of the mechanism 80, and FIG. 4 is a block diagram showing an outline of the configuration of the nozzle inspection device 50.

  As shown in FIG. 1, the printer 20 of the present embodiment includes a printing mechanism 21 having a print head 24 that ejects ink as a fluid onto a printing medium P as a target, and a head driving substrate mounted on a carriage 22. 62, a head height adjusting mechanism 80 (see FIG. 3) capable of adjusting the height of the print head 24 with respect to the platen 29, a paper feed mechanism 30 for conveying the print medium P, and sealing and cleaning of the print head 24. A capping device 31 to be executed, a nozzle inspection device 50 for executing a nozzle inspection to check whether or not ink is being ejected from the print head 24, and a controller 70 for controlling the entire printer 20 are provided.

  The printing mechanism 21 includes a carriage 22 that reciprocates left and right (main scanning direction) along a carriage shaft 28 by a carriage belt 32, and a print head 24 that applies pressure to each color ink and ejects ink droplets as fluid from nozzles 23. And an ink cartridge 26 that stores ink of each color and supplies the stored ink to the print head 24. As the carriage 22 is driven by the carriage motor 34a, the carriage belt 32 laid between the carriage motor 34a attached to the right side of the mechanical frame 39 and the driven roller 34b attached to the left side of the mechanical frame 39 is driven. Move. A linear encoder 25 that detects the position of the carriage 22 is disposed on the rear surface of the carriage 22, and the position of the carriage 22 can be managed using the linear encoder 25. The carriage 22 has a head driving substrate 62 for driving the print head 24. The print head 24 is provided below the carriage 22 and ejects ink of each color from the nozzles 23 provided on the lower surface of the print head 24 by pressurizing the ink. The print head 24 is connected to the ground. On the lower surface of the print head 24, as shown in FIG. 2, a nozzle array in which a plurality of nozzles 23 for ejecting ink of each color of cyan (C), magenta (M), yellow (Y), and black (K) are arranged. 68 is provided. Here, all nozzles are collectively referred to as nozzles 23, all nozzle rows are collectively referred to as nozzle rows 68, cyan nozzles and nozzle rows are nozzles 23C and 68C, magenta nozzles and nozzle rows are nozzles 23M and nozzle rows. The 68M, yellow nozzle and nozzle row are referred to as nozzle 23Y and nozzle row 68Y, and the black nozzle and nozzle row are referred to as nozzle 23K and nozzle row 68K. Hereinafter, description will be given using the nozzle 23K. In the print head 24, 180 nozzles 23K are arranged along the conveyance direction of the print medium P to form a nozzle row 68K. Each nozzle 23K is provided with a piezoelectric element 66 as a drive element for ejecting ink droplets. By applying a voltage to the piezoelectric element 66, the piezoelectric element 66 is deformed to pressurize the ink and press the nozzle 23K. Discharge. The ink cartridge 26 is mounted on the carriage 22 and is used for printing of cyan (C), magenta (M), yellow (Y), black (K), etc. containing pigment or dye as a colorant in water as a solvent. Each color ink to be used is individually accommodated.

  As shown in FIG. 2, the head driving substrate 62 has a mask circuit 64 for applying a voltage to the piezoelectric element 66. The head driving substrate 62 is connected to a flat cable 63 (see FIG. 1) via a connector portion (not shown), and exchanges signals with the controller 70 via the flat cable 63. The mask circuit 64 is provided corresponding to the piezoelectric element 66 that drives each nozzle 23K. The mask circuit 64 receives the original signal ODRV and the print signal PRTn generated by the head drive waveform generation circuit 60 on the control board (not shown). The original signal ODRV is composed of a first pulse P1, a second pulse P2, and a third pulse P3 that are included in an interval of one pixel (within a time during which the carriage 22 crosses the interval of one pixel). The original signal ODRV having these three pulses P1 to P3 as a repeating unit is referred to as one pixel section in this embodiment. The print signal PRTn is a signal generated based on the presence / absence of dots formed on the print medium P and the size thereof. 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. When the original signal ODRV and the print signal PRTn are input, the mask circuit 64 outputs necessary pulses among the first pulse P1, the second pulse P2, and the third pulse P3 based on these signals as the drive signal DRVn (n Is the same as n of the print signal PRTn) and is output toward the piezoelectric element 66 of the nozzle 23K. Specifically, when only the first pulse P1 is output from the mask circuit 64 to the piezoelectric element 66, one shot of ink droplet is ejected from the nozzle 23K, and a small size dot (small dot) is formed on the print medium P. It is formed. When the first pulse P1 and the second pulse P2 are output to the piezoelectric element 66, two shots of ink droplets are ejected from the nozzle 23K, and medium-sized dots (medium dots) are formed on the print medium P. The In addition, when the first pulse P1, the second pulse P2, and the third pulse P3 are output to the piezoelectric element 66, three shots of ink droplets are ejected from the nozzle 23K, and a large size dot (large Dot) is formed. As described above, the printer 20 can form three types of dots by adjusting the amount of ink ejected in one pixel section. The other color nozzles 23C, 23M, and 23Y and the nozzle rows 68C, 68M, and 68Y are the same as the nozzle 23K and the nozzle row 68K.

  As shown in FIG. 3, the platen gap (PG) adjusting mechanism 80 includes a rotatable shaft 81 disposed below the carriage shaft 28 in parallel with the carriage shaft 28, and a cam surface on the lower side of the carriage shaft 28. PG adjusting cams 82 (shown only on one side) attached to both ends of the shaft 81 so as to abut, a reduction gear 83 attached to one end of the shaft 81, and a gear 85 meshing with the reduction gear 83 on the rotating shaft 84a. And an attached PG adjustment motor 84. In the mechanical frame 39, a vertically long through hole 39a is formed so as to allow only the vertical movement of the carriage shaft 28. Then, when the PG adjusting cam 82 rotates with the rotation of the shaft 81 by driving the PG adjusting motor 84, the cam surface that contacts the carriage shaft 28 according to the rotation angle and the cam shaft of the PG adjusting cam 82 ( That is, the distance from the shaft 81) changes. As a result, the carriage shaft 28 moves in the vertical direction along the through hole 39a, and the distance between the print head 24 and the platen 29, that is, the platen gap is adjusted. The rotation angle of the PG adjusting cam 82 is detected by a rotary encoder (not shown) integrated with the reduction gear 83 and transmitted to the controller 70. The platen 29 has a rectangular sponge that can absorb ink and is arranged in parallel to the main scanning direction, and resin ribs are erected on the sponge at appropriate intervals. Denotes the distance between the lower surface of the print head 24 and the top surface of the rib of the platen 29.

  As shown in FIG. 1, the paper feed mechanism 30 is mounted on a paper feed roller 35 that is driven by a drive motor 33 and transports the print medium P from the back to the front of the platen 29 and a tray (not shown). A paper feed roller that feeds the print medium P to the platen 29, a paper discharge roller that transports the print medium P discharged from the platen 29 to a paper discharge tray (not shown), and the like.

  The capping device 31 has a substantially rectangular parallelepiped shape in which a sponge is laid inside a housing formed of an insulating member having an upper opening, and is disposed at an initial position (home position) of the carriage 22. Although not shown, the capping device 31 is provided with a suction pump and an air release valve. The suction pump is used when forcibly sucking out ink from the nozzle 23 by making the inside of the housing negative pressure while the capping device 31 is raised and in close contact with the print head 24 during cleaning. The air release valve is used to return the inside of the housing to atmospheric pressure after the cleaning is completed. The capping device 31 is also used when sealing the nozzles 23 to prevent the nozzles 23 from drying during printing pauses or the like.

  As shown in FIG. 4, the nozzle inspection device 50 has a flushing box (FB) 40 that can receive ink droplets ejected from the nozzles 23 of the print head 24, and the height of the flushing box 40 with respect to the platen 29. An adjustable FB height adjusting mechanism 44 (see FIG. 5) and voltage application that generates a predetermined potential difference between the print head 24 and the electrode member 42 by setting the electrode member 42 in the flushing box 40 to a predetermined potential. The circuit 53 and the voltage detection circuit 54 which detects the voltage change of the electrode member 42 are provided.

  The flushing box 40 is an area for ejecting ink originally for the purpose of preventing clogging of the nozzles 23, but in the present embodiment, it is also an area for receiving ink when performing a nozzle inspection. The flushing box 40 is provided at a position opposite to the home position of the platen 29, specifically, at a position where the print head 24 can always face without being covered with any type of print medium P. Yes. The flushing box 40 includes an ink absorbing member 41 and an electrode member 42 disposed on the upper surface of the ink absorbing member 41. The ink absorbing member 41 is formed of a highly permeable sponge, nonwoven fabric, or the like that allows the landed ink droplets to move downward quickly. The electrode member 42 is a mesh-like thin plate made of stainless steel (SUS). The electrode member 42 serves to prevent the ink absorbing member 41 from absorbing ink and bulging upward, and at the time of nozzle inspection, the print head 24. It also plays a role as a counter electrode opposite to. Since the electrode member 42 is formed in a mesh shape, the ink ejected from the print head 24 is allowed to move to the ink absorbing member 41. When the electrode member 42 is disposed on the upper surface of the ink absorbing member 41, the heads of the three support rods 40a integrally formed on the floor surface of the working chamber 40b are inserted into the round holes provided at the cross points of the mesh. However, it is caulked by heating and pressurizing its head. The electrode member 42 is electrically connected to an electrode pin 43 that penetrates the bottom surface of the working chamber 40b in an airtight and liquidtight state.

  As shown in FIG. 5, the FB height adjusting mechanism 44 includes a spring 46 that is placed on the pedestal 45 and urges the flushing box 40 upward, a guide 47 that slidably supports the outer periphery of the flushing box 40, An FB adjustment cam 48 rotatably supported in a working chamber 40b provided below the flushing box 40, and an FB adjustment motor 49 having a rotation shaft 49a fixed to the FB adjustment cam 48 are provided. Yes. The pedestal 45, the guide 47, and the FB adjustment motor 49 are fixed to the mechanical frame 39 (see FIG. 1). The cam surface of the FB adjusting cam 48 constantly presses the floor surface of the working chamber 40b. When the FB adjustment cam 48 rotates as the rotation shaft 49a rotates by driving the FB adjustment motor 49, the cam surface that contacts the floor surface of the working chamber 40b according to the rotation angle and the rotation shaft 49a. , The flushing box 40 moves up and down along the guide 47, and the height of the electrode member 42 of the flushing box 40 relative to the platen 29 is adjusted. The rotation angle of the FB adjustment cam 48 is detected by a rotary encoder (not shown) integrated with the rotation shaft 49 a and transmitted to the controller 70.

  As shown in FIG. 3, the voltage application circuit 53 is connected to the electrode member 42 in the flushing box 40, and the voltage of the electrical wiring of several volts drawn inside the printer 20 is passed through a booster circuit (not shown). In this circuit, the voltage is boosted to several tens to several hundreds volts, and the boosted DC voltage Ve (for example, 400 V) is applied to the electrode member 42 via the resistance element R1 (for example, 1 MΩ) and the switch SW.

  The voltage detection circuit 54 is connected to the electrode member 42 in the flushing box 40 and detects a voltage change at the electrode member 42 caused by ink ejection. The voltage detection circuit 54 integrates and outputs the voltage signal of the print head 24. The integration circuit 54a, the inverting amplification circuit 54b that receives and inverts and outputs the signal output from the integration circuit 54a, and the signal that is output from the inverting amplification circuit 54b are input and A / D converted. And an A / D conversion circuit 54c for outputting to the controller 70. The integration circuit 54a outputs a large voltage change by integrating the voltage change due to the flight of a plurality of ink droplets ejected from the same nozzle 23 because the voltage change due to the flight of one ink droplet is weak. is there. The inverting amplifier circuit 54b inverts the sign of the voltage change and amplifies and outputs the signal output from the integrating circuit 54a 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 it to the controller 70.

  The controller 70 is mounted on a control board (not shown) attached to the mechanical frame 39, and is configured as a microprocessor centered on the CPU 72 as shown in FIG. 1, and can store various processing programs and rewrite data. A flash ROM 73, a RAM 74 for temporarily storing data and storing data, and an interface (I / F) 75 for exchanging data with an external device such as a user personal computer (PC) 110 are provided. In the flash ROM 73, in addition to each processing program such as a printing processing routine and a nozzle inspection routine, a correspondence table between the type of printing medium and the platen gap is stored. Table 1 shows an example of the correspondence table. The thickness of each print medium is plain paper <postcard <envelope <CD. The RAM 74 is provided with a print buffer area. A print job (information about the type of image data or print medium) sent from the external device such as the user personal computer (PC) 110 via the I / F 75 is stored in the RAM 74. Etc.) are stored. In addition to a detection signal output from the voltage detection circuit 54 of the nozzle inspection device 50 being input to the controller 70 via an input port (not shown), a print job output from an external device (such as the user personal computer 110). Etc. are input via the I / F 75. In addition to the control signal to the mask circuit 64 mounted on the print head 24 and the drive signal to the drive motor 33, the controller 70 supplies the PG adjustment motor 84, the FB adjustment motor 49, and the carriage motor 34a. A drive signal or the like is output via an output port (not shown).

  Next, the operation of the printer 20 of this embodiment configured as described above will be described. Here, first, the operation of the main routine will be described with reference to FIG. FIG. 6 is a flowchart showing an example of the main routine. This routine is executed by the CPU 72 every predetermined timing after the printer 20 is turned on.

  When the main routine is started, the CPU 72 first determines whether there is a print job waiting for printing in the print buffer area of the RAM 74 (step S100). The print job received from the user PC 110 is temporarily stored in the print buffer area formed in the RAM 74 and becomes a print job waiting for printing. If there is no print job waiting to be printed in step S100, this main routine is terminated as it is. On the other hand, when there is a print job waiting for printing, the image data included in the print job waiting for printing and the type of print medium as the fluid ejection condition are input (step S110), and the type of the input print medium is supported. The platen gap to be read is read from the correspondence table (see Table 1) (step S120). Subsequently, the PG adjustment routine, the FB height adjustment routine, and the nozzle inspection routine are executed in this order.

  In the PG adjustment routine, the CPU 72 first drives the PG adjustment motor 84 (step S130), calculates a platen gap based on a rotation angle received from a rotary encoder (not shown) integrated with the reduction gear 83, and Wait until the platen gap matches the read platen gap (step S140). Since the rotation angle of the reduction gear 83 corresponds to the distance from the cam shaft (shaft 81) to the cam surface (carriage shaft 28) in the PG adjustment cam 82, the CPU 72 determines the platen based on the rotation angle of the reduction gear 83. The gap can be calculated. If the platen gap matches the platen gap read from the correspondence table, the PG adjustment motor 84 is stopped (step S150).

  In the subsequent FB height adjustment routine, the CPU 72 first determines the height (from the rib top surface of the platen 29 to the upper surface of the electrode member 42 based on the platen gap read from the correspondence table and a predetermined sensor gap (SG) ( A target value of (FB height) is set (step S160). Here, the sensor gap is a value that is determined so that the sensitivity of the output signal waveform is optimal when performing the nozzle inspection, and is set to 2 mm or 4 mm, for example. This sensor gap is stored in the flash ROM 73. After setting the target value of the FB height in step S160, the FB height adjustment motor 49 is driven (step S170), and the FB is based on the rotation angle received from a rotary encoder (not shown) integrated with the rotation shaft 49a. The height is calculated and waits until the calculated FB height matches the target value (step S180). Since the rotation angle of the rotation shaft 49a corresponds to the distance from the cam shaft (rotation shaft 49a) of the FB adjustment cam 48 to the cam surface (floor surface of the working chamber 40b), the CPU 72 rotates the rotation angle of the rotation shaft 49a. The FB height can be calculated based on the above. If the FB height matches the target value, the FB adjustment motor 49 is stopped (step S190). An example of the positional relationship between the print head 24 and the flushing box 40 at the time when step S190 is completed is shown in FIG. FIG. 8A shows an example when the print medium is thin like plain paper, and FIG. 8B shows an example when the print medium is thick like CD. As is apparent from FIG. 8, the platen gap (PG) is wider when the print medium is thicker than when it is thin, but the sensor gap (SG) is the same.

  In setting the target value of the FB height, the print head height when the platen gap is adjusted based on the read platen gap and the sensor gap determined in advance is adjusted based on the read platen gap. A target value for the FB height may be set. Also in this case, the target value of the FB height is set based on the read platen gap and a predetermined sensor gap.

  In the subsequent nozzle inspection routine (step S200), it is inspected whether or not ink droplets are ejected from each nozzle of the print head 24. FIG. 7 is a flowchart illustrating an example of a nozzle inspection routine. When this nozzle inspection routine is started, the CPU 72 first drives the carriage motor 22a until the print head 24 comes to a position facing the flushing box 40 (step S300). Subsequently, an inspection target nozzle row and an inspection target nozzle are set (step S310). The inspection target nozzle row is set in the order of yellow (Y) nozzle row 68Y, magenta (M) nozzle row 68M, cyan (C) nozzle row 68C, and black (K) nozzle row 68K. The nozzle setting order is from the first nozzle 23 to the 180th nozzle 23 in order. Next, the switch SW of the voltage application circuit 53 is turned on (step S320). As a result, a voltage (400 V) is applied between the print head 24 and the electrode member 42. Subsequently, the mask circuit 64 and the piezoelectric element 66 of the print head 24 are controlled so that ink is ejected from the inspection target nozzles 23 of the inspection target nozzle row 68 (step S330), and the print head 24 and the electrode member 42 at that time are controlled. It is determined whether or not the level (amplitude) of the output signal waveform between them is equal to or greater than the threshold value Vthr (step S340).

  Here, the principle of nozzle inspection will be described. An experiment was conducted in which an ink droplet was ejected from the nozzle 23 in a state where a potential difference was generated between the print head 24 and the electrode member 42 by grounding the print head 24. The output signal waveform appeared as a sine curve. It is considered that the principle that such an output signal waveform is obtained is that an induced current flows due to electrostatic induction as a charged ink droplet is ejected to the electrode member 42. In addition, the amplitude of the output signal waveform output from the voltage detection circuit 54 tends to increase as the distance from the print head 24 to the electrode member 42 decreases, and also increases as the flying ink droplet increases. It was. 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 waveform is smaller than that at the normal time or becomes almost zero, so the output signal waveform Whether or not the nozzle 23 is clogged can be determined based on whether or not the amplitude is less than a predetermined threshold value Vthr. Here, even if the ink droplet has a predetermined size, since the amplitude of the output signal waveform by the ink droplet for one shot is weak, a large number of ink droplets (e.g., the operation of ejecting a large dot is performed eight times) In addition to discharging, the signal is amplified by the inverting amplifier circuit 54b. Therefore, the output signal can be an integrated value of a large number of ink droplets, and a sufficiently large output signal waveform can be obtained from the voltage detection circuit 54. The number of ink ejections can be arbitrarily set so as to be the number of ejections that can ensure inspection accuracy. The threshold value Vthr can be set empirically so that the ejection of ink droplets can be determined.

  When the output level is less than the threshold value Vthr in step S340, it is considered that an abnormality such as clogging has occurred in the nozzle to be inspected this time, and information for specifying the nozzle (for example, what number nozzle in which nozzle row) Information) is stored in a predetermined area of the RAM 74 (step S350). After step S350 or when the output level is equal to or higher than the threshold value Vthr in step S340 (that is, when the current nozzle to be inspected is normal), the CPU 72 has inspected all the nozzles included in the current nozzle row to be inspected. If there is a nozzle that has not been inspected yet, the nozzle to be inspected is updated to an uninspected nozzle (step S370), and then the processing after step S330 is performed again. On the other hand, when all the nozzles 23 included in the current inspection target nozzle row have been inspected in step S360, it is determined whether or not all the nozzle rows 68 included in the print head 24 have been inspected (step S380). If the uninspected nozzle row 68 remains, the inspection target nozzle row is updated to the uninspected nozzle row 68 and the inspection target nozzle is set to the first nozzle in the updated inspection target nozzle row (step S390), and thereafter, the processing after step S330 is performed again. On the other hand, when all the nozzle arrays 68 included in the print head 24 have been inspected in step S380, the switch SW of the voltage application circuit 53 is turned off (step S400), and this nozzle inspection routine ends.

  After returning to the main routine of FIG. 6 and executing the nozzle inspection routine (step S200) described above, the CPU 72 stores a predetermined area in the RAM 74 as to whether or not there is an abnormal nozzle 23 among all the nozzles 23. The determination is made based on the contents (step S210), and when there is a nozzle 23 in which an abnormality has occurred, the print head 24 is cleaned, but the number of cleanings performed before that to eliminate the abnormality is the upper limit (for example, 3 times) is determined (step S220). If the number of cleanings is less than the upper limit, the print head 24 is cleaned (step S230). This cleaning process is executed using the capping device 31 as described above. After executing the cleaning process, the process returns to the nozzle inspection routine in step S200 again to check whether the abnormality of the nozzle 23 has been resolved. On the other hand, if the number of cleanings reaches the upper limit in step S220, 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 S240). ) This main routine is terminated. On the other hand, if there is no abnormal nozzle 23 in step S210, the print medium P conveyed on the platen 29 while moving the print head 24 in the main scanning direction based on the image data included in the print job. The ink is ejected toward the printer to execute the printing process on the print medium P (step S250), and the main routine is terminated. In executing the printing process, the platen gap suitable for the print medium P of this time has already been adjusted in the PG adjustment routine, so that the work of adjusting the platen gap becomes unnecessary.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. The printer 20 of the present embodiment corresponds to the fluid ejection device of the present invention, the print head 24 corresponds to the head, the flushing box 40 corresponds to the inspection area, and the head height adjustment mechanism 80 corresponds to the head height adjustment means. The FB height adjusting mechanism 44 corresponds to the inspection area height adjusting means, the RAM 74 corresponds to the storage means, and the CPU 72 corresponds to the platen gap reading means, the head height control means, the inspection area height control means, and the fluid discharge conditions. It corresponds to an input unit, an image data input unit, and an image forming unit.

  According to the present embodiment described above, the adjustment of the platen gap by the head height adjusting mechanism 80 and the adjustment of the sensor gap by the FB height adjusting mechanism 44 are performed before and after, so that the timing for performing the nozzle inspection thereafter. Even if it arrives, the interval between the print head 24 and the electrode member 42 has already become a predetermined sensor gap, and the nozzle inspection can be immediately executed. Therefore, it is possible to prevent the time required for the nozzle inspection from being prolonged. Further, when executing the printing process, since the interval between the print head 24 and the platen 29 has already been adjusted to a platen gap suitable for the printing medium P, the printing process can be immediately executed. Accordingly, it is possible to prevent the time required for the printing process from being prolonged. Further, in the nozzle inspection described above, if the distance (sensor gap) between the print head 24 and the electrode member 42 is too wide, the sensitivity may be lowered and erroneous determination may be caused. Therefore, the sensor gap is set to an appropriate distance. Therefore, the significance of applying the present invention is high.

  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, in the embodiment described above, the adjustment of the sensor gap is performed after the adjustment of the platen gap. However, the adjustment of the sensor gap may be performed before the adjustment of the platen gap, or both may be performed in parallel. May be executed.

  In the above-described embodiment, the platen gap and the sensor gap are adjusted before executing the printing process. However, although the platen gap needs to be adjusted before the printing process is executed, the sensor gap is not adjusted. It is not always necessary to perform the printing process before executing it, and it is sufficient to perform it before executing the nozzle inspection. Specifically, the main routine shown in FIG. 9 and the inspection monitoring routine shown in FIG. 10 may be executed. When the main routine is started, the CPU 72 determines whether or not there is a print job waiting to be printed (step S500). If there is no print job, the main routine is ended. On the other hand, if there is a print job waiting to be printed, the image data and print medium type included in the print job are input (step S510), and the platen gap corresponding to the print medium type is read from the correspondence table (step S510). In step S520, a PG adjustment routine is executed (step S530). Thereafter, a printing process is executed (step S540), and the main routine is terminated. Steps S510 and 520 are the same as steps S110 and 120 described above, step S530 is the same as steps S130 to S150 described above, and step S540 is the same as step S250 described above. The inspection monitoring routine is executed in parallel with the main routine after the end of the PG adjustment routine in step S530. When the inspection monitoring routine is started, as shown in FIG. 10, the CPU 72 determines whether or not the nozzle inspection timing has arrived (step S700). Here, it is assumed that the nozzle inspection timing is generated at a predetermined timing before or during the start of the printing process, for example, at the end of printing a predetermined number of pages or at a predetermined pass. If the nozzle inspection timing has come in step S700, it is determined whether or not the distance from the lower surface of the print head 24 to the upper surface of the electrode member 42 matches a predetermined sensor gap (step S710). An FB height adjustment routine is executed (step S720). Then, after the execution of the FB height adjustment routine or when an affirmative determination is made in step S710, a nozzle inspection routine is executed (step S730), and then it is determined whether there is an abnormal nozzle (step S740). If there is, there is executed processing in steps S750 to 770 similar to steps S220 to S240 described above. If there is no abnormal nozzle, this routine is terminated. If there is no abnormal nozzle, the printing process is started before the start of the printing process, and the printing process is restarted before the end of the printing process. At this time, since the platen gap remains adjusted to fit the printing medium P, the operation of changing the platen gap is not necessary, and it is possible to prevent the time required for printing from being prolonged.

  In the above-described embodiment, the nozzle inspection is performed using the voltage change between the print head 24 and the electrode member 42 accompanying the ejection of the ink droplets. However, the nozzle inspection may be performed using a laser beam. That is, as shown in FIG. 11, the light emitting element 102 and the light receiving element 104 are installed in the flushing box 40, the laser light emitted from the light emitting element 102 and incident on the light receiving element 104, and the ink ejected from the predetermined nozzle 23. After the print head 24 is arranged at a position where the nozzles intersect, and the ink is ejected from the nozzle 23, it is determined whether the laser beam is blocked by the ink based on the output signal of the light receiving element 104, and the block 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 the embodiment described above, the electrode member 42 in the flushing box 40 is disposed on the upper surface of the ink absorbing member 41, but it may be disposed so as to be sandwiched between the middle stages of the ink absorbing member 41. In this case, the ink absorbing member 41 may be conductive, but the ink absorbing member 41 may be non-conductive because the ink is water-soluble and conductive. Further, as shown in FIG. 12, instead of the electrode member 42, an electrode member 142 is provided in the vicinity of the position where the ink ejected from the nozzle 23 passes, and this occurs when the ink passes in the vicinity of the electrode member 142. The electrical change may be detected by the voltage detection circuit 54, and the ink ejection state may be detected based on the detection result. The electrode member 142 may be an electrode plate or an electric wire as long as it can detect an electrical change accompanying the passage of ink.

  In the above-described embodiment, the print head 24 is connected to the ground and a voltage is applied to the electrode member 42 to generate a potential difference between the print head 24 and the electrode member 42. However, the electrode member 42 is connected to the ground. The voltage difference may be generated between the print head 24 and the electrode member 42 by applying a voltage to the print head 24. Further, the potential of the electrode on the side connected to the ground is not limited to the ground but may be a potential that is different from the voltage of the voltage application circuit 53 and gives a predetermined potential difference with the voltage of the voltage application circuit 53. Good. Note that the electrode that applies a predetermined potential in the print head 24 may be any electrode that can conduct the ink in the print head 24 and apply a potential to the ink, such as a nozzle plate or an electrode in the head.

  In the above-described embodiment, both the circuits 53 and 54 are connected to the electrode member 42. However, both the circuits 53 and 54 are connected to the print head 24, or one of the circuits 53 and 54 is connected to the electrode member 42 and the print head. The other of the circuits 53 and 54 may be connected to the other of the electrode member 42 and the print head 24.

  In the above-described embodiment, the inspection area is provided in the flushing box 40. However, the present invention is not particularly limited thereto, and may be provided in the capping device 31 or newly provided in an area where the print head 24 is movable. Also good.

  In the embodiment described above, the type of the print medium is input as the fluid discharge condition. However, the fluid discharge condition is not limited to the type of the print medium. For example, the recording resolution of an image when fluid is ejected to the print medium based on image data to form an image may be input as fluid ejection information, and the platen gap corresponding to the input recording resolution may be read from the correspondence table. Alternatively, the printer may include a temperature sensor, detect the environmental temperature at the time of fluid ejection, use the detected environmental temperature at the time of fluid ejection as a fluid ejection condition, and read the platen gap corresponding to the environmental temperature. In addition, the fluid ejection conditions included in the print job are input. However, the present invention is not limited to this, and the fluid ejection conditions set on the operation panel of the printer may be input, or the fluid ejection conditions detected by the sensor are input. May be.

  In the above-described embodiment, the print head 24 applies a voltage to the piezoelectric element 66 and deforms the piezoelectric element 66 to pressurize the ink. However, the ink is applied to the heating resistor (for example, a heater) by applying a voltage. A method may be employed in which the ink is pressurized with bubbles generated by heating. The ink cartridge 26 is configured as a so-called on-carriage mounted on the carriage 22 that reciprocates, but may be configured as a so-called off-carriage that is mounted on the mechanical frame 39 and supplies ink or the like to the print head 24 through a tube.

  In the embodiment described above, an example in which the printer 20 that ejects ink onto the print medium P is embodied has been described. However, whether or not fluid is ejected from the nozzle by providing a potential difference between the print head 24 and the electrode member 42. The present invention can be applied without particular limitation as long as it can be detected. For example, it may be a printing device that discharges a liquid (dispersion) in which particles of liquid other than ink or functional material are dispersed, a fluid such as a gel, or a solid that can be discharged as a fluid. The present invention may be embodied in a printing apparatus that discharges. For example, a liquid discharge device that discharges a liquid in which a material such as an electrode material or a color material used for manufacturing a liquid crystal display, an EL (electroluminescence) display, a surface emitting display, and a color filter is dissolved, or a liquid material in which the material is dispersed It is good also as a liquid discharge apparatus which discharges the liquid used as a liquid material discharge apparatus which discharges, and a sample used as a precision pipette. Also, a liquid ejection device that ejects a transparent resin liquid such as an ultraviolet curable resin on a substrate to form a micro hemispherical lens (optical lens) used for an optical communication element or the like, a fluid ejection device that ejects a gel, A powder discharge type recording apparatus that discharges powder such as toner may be used.

  In the above-described embodiment, the printer 20 has been described as the fluid ejection device of the present invention. However, a multifunction printer including a scanner unit capable of reading a document or a FAX device having a FAX function may be used.

  20 printer, 21 printing mechanism, 22 carriage, 23, 23C, 23M, 23Y, 23K nozzle, 24 print head, 25 linear encoder, 26 ink cartridge, 28 carriage shaft, 29 platen, 30 paper feed mechanism, 31 capping device, 32 Carriage belt, 33 Drive motor, 34a Carriage motor, 34b Driven roller, 35 Paper feed roller, 39 Mechanical frame, 39a Through hole, 40 Flushing box, 40a Support rod, 40b Working chamber, 42, 142 Electrode member, 43 Electrode pin 44 FB height adjustment mechanism, 45 base, 46 spring, 47 guide, 48 FB adjustment cam, 49 FB adjustment motor, 49a rotating shaft, 50 nozzle inspection device, 53 voltage application circuit, 54 voltage detection circuit, 5 a integration circuit, 54b inverting amplification circuit, 54c A / D conversion circuit, 60 head drive waveform generation circuit, 62 head drive substrate, 63 flat cable, 64 mask circuit, 66 piezoelectric element, 68, 68C, 68M, 68Y, 68K Nozzle array, 70 controller, 72 CPU, 73 flash ROM, 74 RAM, 75 interface, 80 head height adjusting mechanism, 81 shaft, 82 PG adjusting cam, 83 reduction gear, 84 PG adjusting motor, 84a rotating shaft, 85 Gear, 102 Light emitting element, 104 Light receiving element, 110 User personal computer, P Print medium, R1 Resistance element, SW switch.

Claims (4)

A head having a plurality of nozzles and discharging fluid toward a target conveyed on the platen from the nozzles while moving in the main scanning direction;
An inspection region that is provided at a position that can face the head, and that receives fluid ejected from the nozzle of the head when performing nozzle inspection;
A head height adjusting means for adjusting the height of the head;
Inspection area height adjusting means for adjusting the height of the inspection area;
Storage means for storing fluid discharge conditions in association with a platen gap indicating a height from the platen to the head;
Fluid discharge condition input means for inputting fluid discharge conditions;
A platen gap reading means for reading a platen gap corresponding to the fluid discharge condition input by the fluid discharge condition input means from the storage means;
Head height control means for controlling the head height adjusting means so that the height from the platen to the head becomes the platen gap read from the storage means;
In parallel with or before and after adjusting the height from the platen to the head by controlling the head height adjusting means, based on the predetermined sensor gap and the platen gap read from the storage means An inspection area height control means for calculating a target value of the height of the inspection area and controlling the inspection area height adjusting means so that the height of the inspection area becomes the target value;
A fluid ejection device comprising: A head having a plurality of nozzles and discharging fluid toward a target conveyed on the platen from the nozzles while moving in the main scanning direction;
An inspection region that is provided at a position that can face the head, and that receives fluid ejected from the nozzle of the head when performing nozzle inspection;
A head height adjusting means for adjusting the height of the head;
Inspection area height adjusting means for adjusting the height of the inspection area;
Storage means for storing fluid discharge conditions in association with a platen gap indicating a height from the platen to the head;
Fluid discharge condition input means for inputting fluid discharge conditions;
Image data input means for inputting image data;
A platen gap reading means for reading a platen gap corresponding to the fluid discharge condition input by the fluid discharge condition input means from the storage means;
Before executing the image forming process based on the image data input by the image data input means, the head height adjusting means is set so that the height from the platen to the head becomes the platen gap read from the storage means. A head height control means to control;
Image formation processing means for controlling the head so that an image based on the image data input by the image data input means is formed on the target;
When the timing of the nozzle inspection comes before or during execution of image formation by the image forming processing means, a predetermined sensor gap and a platen gap read from the storage means without controlling the head height adjusting means A target value of the height of the inspection area based on the inspection area height control means for controlling the inspection area height adjustment means so that the height of the inspection area becomes the target value;
A fluid ejection device comprising: In the nozzle inspection, the gap between the head and the inspection region is the sensor gap, and a predetermined voltage is applied between the head and the inspection region so that fluid is discharged from each nozzle of the head. It is an inspection for determining normality / abnormality of each nozzle based on an electrical change between the head and the inspection area when the head is controlled.
The fluid ejection device according to claim 1 or 2. In the nozzle inspection, a light emitting element and a light receiving element are installed in the inspection region, and the print head is placed at a position where light emitted from the light emitting element and incident on the light receiving element intersects with fluid discharged from the nozzle. It is an inspection to determine normality / abnormality of each nozzle based on whether light is blocked by the fluid based on the output signal of the light receiving element after being arranged and operated so that fluid is discharged from each nozzle.
The fluid ejection device according to claim 1 or 2.

Images