JP2010188583A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer capable of suppressing the drying and thickening of ink in an inkjet head in accordance with the operation state of the inkjet printer even in the inkjet printer provided with a heater. <P>SOLUTION: The inkjet printer includes: a medium conveying mechanism conveying a medium; a heating mechanism heating the medium under conveyance by the medium conveying mechanism; and the inkjet head discharging the ink to the medium, to form an image. The inkjet printer further includes a control section allowing the inkjet head to execute one or both of slight vibration and preliminary discharge in accordance with the operation state of the inkjet printer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inkjet printer, and more particularly, to an inkjet printer that forms an image on a wide or long medium.

  In an ink jet printer that forms an image by ejecting ink onto a medium, it is required to keep the quality of the image to be formed constant by preventing the ink from drying on the ink jet head and preventing the increase in viscosity associated with the drying. Various measures have been proposed for this purpose. For example, Patent Document 1 and Patent Document 2 propose that thickening is prevented by giving a slight vibration that does not cause ejection to the ink in the nozzles of the inkjet head when an image is not formed. ing.

JP 2002-221482 A JP 2004-42314 A

  However, in a large-sized inkjet printer that forms an image on a wide or long medium, as proposed in Patent Documents 1 and 2, the ink can be dried and thickened only by giving a slight vibration. It was not enough to suppress. That is, since a large-sized ink jet printer forms an image on a medium for a long time, a nozzle that does not eject ink during this time may be dried and thickened. Further, when the inkjet head is scanned during the cleaning of the inkjet head or when the medium is set, the amount of movement increases corresponding to the medium, and the ink may dry and thicken during that time.

  In addition, in order to promote the drying of the ink on the medium, there is one that heats the medium by providing a heater in a path along which the medium is conveyed. This is the case, for example, when an image is formed on a long medium that needs to be rolled up after image formation. Furthermore, from the viewpoint of stabilizing the image quality, there are some which heat the inkjet head to a constant temperature. In an ink jet printer provided with such a heater, the ink in the ink jet head tends to dry.

  Accordingly, an object of the present invention is to provide an ink jet printer that can suppress drying and thickening of ink in an ink jet head even in an ink jet printer provided with a heater in accordance with the operation state of the ink jet printer.

  In order to solve the above problems, an ink jet printer according to the present invention includes a medium transport mechanism that transports a medium, a heating mechanism that heats the medium being transported by the medium transport mechanism, and ejects ink onto the medium to form an image. An ink jet printer comprising: an ink jet head to be formed, and further comprising a control unit that causes the ink jet head to perform one or both of micro vibration and preliminary ejection according to an operation state of the ink jet printer.

  In the ink jet printer of the present invention, the operation state of the ink jet printer includes a media set sequence performed when a medium is set in the ink jet printer. In the media set sequence, a medium detection sensor provided in a carriage on which the ink jet head is mounted, It is preferable that the thickness of the medium is measured at a plurality of positions, and the control unit causes the fine vibration to be executed in the media set sequence.

  In the ink jet printer of the present invention, at least one of a suction process in which the cap is brought into close contact with the nozzle surface of the ink jet head to suck ink and a wiping process of wiping off the ink on the nozzle surface with a blade are performed in the operation state of the ink jet printer. In the cleaning sequence, the inkjet head and the cap are separated from each other except in the suction step, and the control unit preferably performs a slight vibration in a region where the inkjet head is scanned in the cleaning sequence.

  In the inkjet printer according to the aspect of the invention, it is preferable that the control unit causes the preliminary ejection to be performed in an area other than the image forming area where an image is formed by the inkjet head.

  In the ink jet printer of the present invention, the operation state of the ink jet printer includes an image forming state in which ink is ejected onto a medium to form an image, and the control unit forms an image with an ink jet head in the image forming state. It is preferable to perform the preliminary discharge in an area other than the area.

  In the ink jet printer of the present invention, the operation state of the ink jet printer includes the temperature of the ink jet head, the temperature of the heating mechanism, or the housing temperature of the ink jet printer, and the control unit sets any of these temperatures. When the temperature exceeds the predetermined temperature, it is preferable to cause the ink jet head to execute both the fine vibration and the preliminary discharge, and when both of these temperatures are equal to or lower than the set temperature, it is preferable to execute only the fine vibration.

  In the ink jet printer of the present invention, it is preferable that the control unit stops the operation of the heating mechanism in an operation state other than the image forming state.

  In the ink jet printer of the present invention, the medium transport mechanism includes a feeding side guide for guiding the medium to the image forming area by the ink jet head, and a discharge side guide for guiding the medium in the image forming area in the discharging direction, and a heating mechanism. It is preferable to include a heater provided in each of the feeding side guide and the discharging side guide.

  The ink jet printer of the present invention preferably includes a heater that heats the ink filled in the ink jet head to a predetermined temperature.

  In the ink jet printer of the present invention, a cap unit that sucks ink in the ink jet head from the nozzle surface at both ends in the scanning direction of the ink jet head across an image forming region where an image is formed by the ink jet head, and ink on the nozzle surface by the blade. A wipe unit for wiping off is preferably provided.

  In the inkjet printer of the present invention, the cap unit preferably includes a solvent supply unit that supplies a solvent for dissolving the ink used in the inkjet printer to the nozzle surface.

  In the ink jet printer of the present invention, the preliminary discharge is performed at least one of an area between the image forming area where the image is formed by the ink jet head and the cap unit, and an area between the image forming area and the wipe unit. It is preferable.

  According to the present invention, drying and thickening of ink in an ink jet head can be suppressed even in an ink jet printer provided with a heater according to the operation state of the ink jet printer.

FIG. 2 is a perspective view showing the configuration of the ink jet printer according to the embodiment of the present invention as viewed from above the medium discharge side. FIG. 4 is a side view illustrating a configuration related to a medium transport path in the inkjet printer according to the embodiment of the present invention. 1 is a block diagram illustrating a configuration of an inkjet printer according to an embodiment of the present invention. It is a front view which shows the process of the cleaning sequence of the inkjet printer which concerns on embodiment of this invention, Comprising: (a) is the state during suction, (b) is the state which introduce | transduced air after suction, (c) is suction FIG. 6D is a diagram illustrating a state in which the inkjet head and the cap are separated later, and FIG. 8D is a diagram illustrating a state during the wiping process by the wipe unit. It is a front view which shows the process of the media set sequence of the inkjet printer which concerns on embodiment of this invention, Comprising: (a) is the state which covered the inkjet head with the cap, (b) is the state which spaced apart the inkjet head and the cap (C) shows the state in which the medium sensor of the inkjet head has moved from above the platen to above one end of the medium, and (d) shows the state in which the medium sensor has moved from above the other end of the medium onto the platen. FIG.

  Hereinafter, an inkjet printer according to an embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, FIG. 2, or FIG. 3, the ink jet printer 10 according to the present embodiment includes a medium transport mechanism 20, an ink jet head 31, a preheater 25 as a heating mechanism, an after heater 26, and a platen heater 41. The head heater 32 and a control circuit 70 as a control unit are provided.

  The control circuit 70 can be configured as a dedicated circuit, or can be realized by a general-purpose CPU (Central Processing Unit) operating according to a control program stored in advance in a ROM (Read Only Memory).

  Here, FIG. 1 is a perspective view showing the configuration of the ink jet printer 10 according to the present embodiment as viewed from above the medium discharge side. FIG. 2 is a side view illustrating a configuration related to a medium transport path. FIG. 3 is a block diagram showing the configuration of the ink jet printer 10. 4A and 4B are diagrams showing a cleaning sequence process of the ink jet printer 10, wherein FIG. 4A shows a state during suction, FIG. 4B shows a state where air is introduced after suction, and FIG. 4C shows an ink jet head after suction. (D) is a figure which respectively shows the state in the process of wiping off by a wipe unit. 5A and 5B are diagrams showing a process of media setting sequence of the ink jet printer 10, wherein FIG. 5A shows a state in which the ink jet head is covered with a cap, FIG. 5B shows a state in which the ink jet head is separated from the cap, (c) is a diagram showing a state in which the medium sensor of the inkjet head is moved from above the platen to above one end of the medium, and (d) is a diagram showing a state in which the medium sensor is moved from above the other end of the medium to the platen. is there. 4 and 5 are front views of the platen 40, the wipe unit 50, and the cap unit 60 as viewed from the medium discharge side.

  Below, the detailed structure of each member is demonstrated.

  The medium transport mechanism 20 feeds a medium that is an object of image formation to an image forming area between the inkjet head 31 and the platen 40 and discharges the medium on which an image is formed by the inkjet head 31. Here, the medium is an object of image formation by the ink jet head 31 and includes long and roll-like materials, and examples thereof include paper and cloth.

  Here, the platen 40 has a long plate shape, is formed by, for example, aluminum extrusion, and is fixed to the upper surface of the fixing portion 13 provided in the main body 12 of the inkjet printer 10. As shown in FIG. 2, the platen 40 is disposed below the inkjet head 31 so that the width direction W thereof is parallel to the conveyance direction of the medium. The platen 40 is formed with a plurality of suction holes (not shown) penetrating in the thickness direction. The medium conveyed on the platen 40 can be sucked by setting the inside of the suction hole to a negative pressure by the operation of a suction device (not shown) provided in the main body 12 of the inkjet printer 10.

  In the platen 40, platen heaters 41 made of linear electric resistors are respectively disposed in a plurality of grooves formed on the lower surface thereof. The operation of the platen heater 41 is controlled by the control circuit 70. The temperature of the platen 40 is measured by a temperature sensor provided in the platen heater 41, and the measurement result is output to the control circuit 70.

  The platen heater 41 may have a form or material other than the linear electric resistor as long as the entire platen 40 can be heated uniformly. Further, instead of the long plate-like platen 40, a cylindrical or drum-like platen can be used. In this case, for example, a columnar electric resistor is disposed inside and the platen is heated.

  The medium transport mechanism 20 includes a curved plate-shaped feeding side guide 21 that guides the medium onto the platen 40, and a curved plate-shaped discharge side guide 22 that guides the medium after image formation away from the platen 40. Prepare. The medium is conveyed along the feeding direction F1 shown in FIGS. 2 and 3 by the feeding side guide 21, and is conveyed along the discharging direction F2 shown in FIGS.

  If the feeding side guide 21 is made of, for example, iron, the rigidity can be increased. When the discharge side guide 22 is made of, for example, aluminum, the weight can be reduced, and the discharge side guide 22 can be easily removed during transportation, packing, and the like. Further, the medium conveyance direction is the feeding direction F1 upstream of the platen 40, and the discharge direction F2 downstream of the platen 40.

  When the medium is in the form of a roll, it is supplied from a supply unit (not shown) arranged on the upstream side in the transport direction with respect to the feeding side guide 21 and is wound on the side (not shown) arranged on the downstream side with respect to the discharge side guide 22. It is wound up by the take-up part. A predetermined tension is applied to the medium by the supply unit, the winding unit, and the conveyance rollers 23 a and 23 b disposed between the feeding side guide 21 and the platen 40. When the lower roller 23b is rotationally driven, the upper roller 23a is driven to rotate, and the medium is conveyed between the two rollers.

  The operation of the medium transport mechanism 20 is controlled by the control circuit 70.

  As shown in FIG. 2, the carriage 30 holds an inkjet head 31 inside. The number of inkjet heads 31 held by the carriage 30 is arbitrarily determined according to the specifications of the inkjet printer 10.

  The carriage 30 is reciprocated in the scanning direction by the carriage drive mechanism 33. This scanning direction is along the direction in which the long plate-like platen 40 extends and is orthogonal to the medium transport direction. The operation of the carriage drive mechanism 33 is controlled by the control circuit 70.

  The inkjet head 31 includes a predetermined number of nozzles that eject ink downward, and ejects ink onto the medium fed by the medium transport mechanism 20. Ink is ejected from one or more nozzles corresponding to the image to be formed. A desired image is formed on the medium by repeating ink ejection and medium conveyance. Detailed description of the configuration of the inkjet head 31 is omitted.

  Ink ejection from the inkjet head 31 is performed under the control of the control circuit 70 based on the image data stored in the memory 71. The image data stored in advance in the memory 71 may be data input from an input device (not shown). As the memory 71, any storage device can be used according to the specification.

  In addition to the inkjet head 31, the carriage 30 includes a head heater 32, a temperature sensor 34, and a medium detection sensor 35.

  The head heater 32 heats the ink in the inkjet head 31 and maintains it at a predetermined temperature. For example, an electric resistor element is used. The head heater 32 is preferably provided in the vicinity of the inkjet head 31 and may be disposed on or in the inkjet head 31. The operation of the head heater 32 is controlled by the control circuit 70.

  The temperature sensor 34 is for measuring the temperature of the inkjet head 31, and uses, for example, a thermistor. The detection result by the temperature sensor 34 is output to the control circuit 70 and stored in the memory 71.

  The medium detection sensor 35 is a sensor that detects the width and thickness of the medium conveyed on the platen 40, and uses, for example, an optical sensor that detects the intensity of reflected light. The detection of the width and thickness of the medium is performed while scanning the carriage 30 on the medium in the media set sequence under the control of the control circuit 70. The detection result is output to the control circuit 70 and stored in the memory 71.

  As a heating mechanism, in addition to the platen heater 41, a preheater 25 and an after heater 26 are provided. The pre-heater 25 and the after-heater 26 are made, for example, by heating a heater wire made of an electric resistor in a predetermined shape on an aluminum foil. The pre-heater 25 and the after-heater 26 are respectively fixed to the lower surface of the feed side guide 21 and the lower surface of the discharge side guide 22 by double-sided tape, for example. The pre-heater 25 and the after-heater 26 may be in a form and material other than the linear electric resistor as long as the feeding-side guide 21 and the discharge-side guide 22 can be heated uniformly.

  The operations of the pre-heater 25 and the after-heater 26 are controlled by the control circuit 70 and are maintained at a temperature corresponding to the operation state and environment of the inkjet printer 10. The temperature is measured by temperature sensors provided in the pre-heater 25 and the after-heater 26, and the measurement results are output to the control circuit 70, respectively.

  Further, a back plate 24 is disposed below the discharge side guide 22. The back plate 24 is preferably formed of a material having the same thermal expansion coefficient as that of the discharge side guide 22 and can prevent distortion due to expansion and contraction due to heat. By disposing the back plate 24 in this way, a space can be formed in the lower portion of the after heater 26 and heat can be prevented from escaping. Further, if a heat insulating material is interposed between the back plate 24 and the discharge side guide 22, it becomes difficult for heat to be transmitted to the back plate 24, and the heat of the discharge side guide 22 can be held.

  A bar-shaped guide bar 14 is disposed above the discharge-side guide 22 so as to be parallel to the longitudinal direction L of the platen 40 at a position away from the medium. By providing the guide bar 14, it is possible to prevent the user of the ink jet printer 10 or the peripheral object of the ink jet printer 10 from touching the medium or the high temperature portion of the surface of the discharge side guide 22.

  4 and 5, a cap unit 60 is provided on the left side of the platen 40 in the longitudinal direction, that is, the scanning direction of the carriage 30, and a wipe unit 50 is provided on the right side. In addition, spit areas 42 and 43 are provided on both ends of the upper surface of the fixed portion 13 to which the platen 40 is fixed and where the medium M is not conveyed.

  The wipe unit 50 includes a blade-like wiper 51 having elasticity, and a drive mechanism 52 that drives the wiper 51. The wiper 51 is made of rubber, for example, and moves in the sub-scanning direction, that is, the direction orthogonal to the scanning direction of the carriage 30 by a driving mechanism. By moving in this manner, the tip surface of the wiper 51 can wipe the nozzle surface of the inkjet head 31 that has stopped moving from the platen 40 to a predetermined position above the wipe unit 50. By cleaning the nozzle surface in this manner, the ink ejected from the nozzle can reach the medium M along a desired locus. The operation of the drive mechanism 52 is controlled by the control circuit 70.

  The cap unit 60 includes a cap 61, an elevating mechanism 62, a pump 63, and a valve 64. The cap 61 covers the nozzle surface of the inkjet head 31 in an airtight state from below, and is moved up and down by the lifting mechanism 62. The pump 63 sucks ink from the nozzle surface through the cap 61. The valve 64 switches between a state where the atmosphere is introduced between the cap 61 and the pump 63 and a state where the cap 61 and the pump 63 communicate with each other to block the atmosphere. The operations of the elevating mechanism 62, the pump 63, and the valve 64 are controlled by the control circuit 70, respectively.

  The cap unit 60 may include a solvent supply unit that stores therein a solvent that can dissolve the ink used in the inkjet printer 10. According to this configuration, when the ink jet head 31 is capped, the nozzle surface is immersed in the solvent supply unit, so that the ink can be prevented from being solidified on the nozzle surface.

  In the spit areas 42 and 43, preliminary ejection is performed for all nozzles in a predetermined pattern. The preliminary ejection is preferably performed in any of the operation states of the media set sequence, the cleaning sequence, and the image forming state. Further, when the temperature detected by the temperature sensor 34 of the carriage 30 exceeds a predetermined temperature, the frequency of preliminary ejection may be increased. Even in other operating states, it is preferable to perform preliminary ejection when the temperature detected by the temperature sensor 34 exceeds a predetermined temperature.

  An arbitrary number of spit areas can be set at arbitrary positions according to the specifications of the inkjet printer 10. Therefore, it may be provided only at one end of the platen 40. In addition, when there is an area where a preliminary ejection pattern can be formed on the medium, the area can be used as a spit area.

  As described above, when the wipe unit 50 and the cap unit 60 are arranged at both ends of the carriage 30 in the scanning direction, the cleaning opportunity increases in the reciprocating scanning of the carriage 30, so that drying and thickening of ink at the nozzles can be suppressed. . This is highly effective when a wide medium M is used.

  Further, by providing a spit area in the scanning path of the carriage 30, it is possible to enhance the effect of preventing ink drying and thickening at the nozzles. Further, in the case where the platen 40 is disposed between the wipe unit 50 and the cap unit 60 as in the inkjet printer 10 according to the present embodiment, the carriage 30 is moved after the wiping in the wipe unit 50 to the medium. When scanning the cap unit 60 across the M, or when scanning the carriage 30 to the wipe unit 50 after suction in the cap unit 60, the ink is dried and thickened during scanning by performing preliminary ejection. That can be suppressed.

  In the ink jet printer 10, the control circuit 70 causes the ink jet head 31 to execute one or both of the fine vibration and the preliminary ejection in accordance with the operation state, and suppresses drying and thickening of the ink. Here, the fine vibration means that the ink jet head 31 is driven so as to cause the ink to vibrate slightly so as not to be ejected. Preliminary ejection refers to ejecting ink in a predetermined pattern to an area other than the image forming area.

  Further, in an operating state other than the image forming state, power supply to the pre-heater 25, the after heater 26, the platen heater 41, and the head heater 32 is stopped or maintained at a temperature that takes into account the rise time at the start of image formation. .

  Hereinafter, drying and thickening prevention processing in the cleaning sequence and the media set sequence will be described.

  An example of the cleaning sequence process will be described with reference to FIG. The cleaning sequence includes a suction process by the cap unit 60 shown in FIGS. 4A and 4B and a wiping process by the wipe unit 50 shown in FIG. 4D. The order of the suction process and the wiping process and the number of treatments can be arbitrarily determined. The cleaning sequence may be executed in an order other than the following example, and only one of the suction process and the wiping process may be performed.

  In the cleaning sequence, the head heater 32 is turned off in all processes. As a result, the ink is dried and thickened during the suction process and the wiping process, and further between the suction process and the wiping process, while the carriage 30 is scanned between the wipe unit 50 and the cap unit 60. Can be suppressed.

  Furthermore, in addition to the head heater 32, the preheater 25, the platen heater 41, and the after heater 26 are also stopped from power supply, that is, turned off, so that the effect of preventing ink drying and thickening can be enhanced. On the other hand, the pre-heater 25, the platen heater 41, and the after heater 26 may be controlled at a temperature lower than that at the time of image formation, and this can also suppress ink drying and thickening.

  In the case where the cleaning sequence is executed in the middle of the image forming process and the process returns to the image forming process again, the preheater 25, so as to smoothly return to the image forming while suppressing the drying and thickening of the ink. It is preferable to lower the heating temperature while the after heater 26, the platen heater 41, and the head heater 32 are in the on state.

  In the suction process, as shown in FIG. 4A, first, the cap 61 is brought into close contact with the nozzle surface of the inkjet head 31 and the valve 64 is operated so as to shut off the atmosphere, and then the pump 63 is driven to perform inkjet. Ink is sucked from the head 31. The suction is performed by driving the pump 63 with a predetermined drive voltage for a predetermined time. After the suction, the driving of the pump 63 is stopped, and the state of the cap 61 and the valve 64 is maintained for a predetermined time for a predetermined time. It should be noted that slight vibration is not performed during suction and after that.

  Subsequently, as shown in FIG. 4B, the valve 64 is opened and the atmosphere is introduced. Next, the elevating mechanism 62 is driven, and the cap 61 is moved downward so that the inkjet head 31 and the cap 61 are separated as shown in FIG. From this state, the carriage drive mechanism 33 is driven to scan the carriage 30 toward the wipe unit 50.

  In the process of scanning from the cap unit 60 to the wipe unit 50, it is preferable to preliminarily eject ink in a predetermined pattern to the spit areas 42 and 43. Thereby, while adjusting the meniscus shape of the ink in a nozzle, drying and thickening of an ink can be suppressed.

  Micro-vibration is performed from when the inkjet head 31 and the cap 61 are separated until the carriage 30 is scanned to the wipe unit 50. Thereby, it is possible to suppress the ink from drying and thickening due to the nozzle surface being exposed without discharging the ink.

  Next, as shown in FIG. 4D, a wiping process is performed in the wipe unit 50. Wiping is performed by stopping the scanning of the carriage 30 at a predetermined position above the wipe unit 50 and moving the wiper 51 along the sub-scanning direction. By this movement, the ink attached to the nozzle surface is wiped off to the tip surface of the wiper 51. The wiper 51 reciprocates a predetermined number of times at a predetermined speed under the control of the control circuit 70.

  In the wiping process, the nozzle of the inkjet head that is being wiped is not vibrated, but the nozzle of the inkjet head that is not being wiped is preferably vibrated.

  Note that the number of wipers 51 corresponding to the number of inkjet heads 31 may be provided.

  The inkjet head 31 that has completed the wiping process returns to the position facing the cap unit 60 and returns to the state in which the cap 61 is in close contact with the nozzle surface as shown in FIG. Even in the process of returning to the cap unit 60, it is preferable to perform slight vibration, and it is better to perform preliminary discharge.

  Next, an example of the media set sequence process will be described with reference to FIG.

  The media set sequence starts from a state in which the nozzle surface of the inkjet head 31 is covered with a cap 61 as shown in FIG. On the other hand, the medium M is transported by the medium transport mechanism 20 to a position that has passed between the inkjet head 31 and the platen 40.

  Next, the elevating mechanism 62 is driven to move the cap 61 downward so that the inkjet head 31 and the cap 61 are separated from each other as shown in FIG. From this state, the carriage drive mechanism 33 is driven to scan the carriage 30 toward the wipe unit 50.

  In the scanning of the carriage 30, the medium detection sensor 35 first detects one end of the medium M when the carriage 30 moves from the platen 40 to the medium M as shown in FIG. Furthermore, as shown in FIG. 5D, when the carriage 30 scanned toward the wipe unit 50 moves from the medium M to the platen 40, the medium detection sensor 35 detects the other end. The detection results for both ends are stored in the memory 71, respectively. Based on the detection result stored in the memory 71, the control circuit 70 calculates the length of the medium M in the scanning direction of the carriage 30 as the width of the medium M and stores it in the memory 71.

  The medium detection sensor 35 detects the thickness of the medium M during the scanning on the medium M. This thickness detection is performed at a plurality of positions while conveying the medium M at a low speed. The thickness detection result is stored in the memory 71. The control circuit 70 calculates the average thickness of the medium M from the stored thickness detection results for a plurality of times.

  The media set sequence preferably performs a plurality of detections and thickness detections at both ends of the medium M described above. When these detections are completed, the control circuit 70 scans the carriage 30 toward the cap unit 60, closes the cap 61 to the nozzle surface of the inkjet head 31 stationary on the cap unit 60, and completes the media setting sequence. To do. Note that it is preferable to suck the ink using the pump 63 after the end of the sequence because the effect of preventing drying and thickening of the ink is enhanced.

  In the media set sequence, the ink jet head 31 and the cap 61 are separated from each other, and then the ink jet head 31 is capped again with the cap 61 until a slight vibration is generated. Thereby, even when the nozzle surface is exposed without ejecting ink, it is possible to prevent the ink from drying and thickening.

  Further, it is preferable to perform preliminary ejection in a predetermined pattern in the spit areas 42 and 43 during scanning of the carriage 30. Thereby, while adjusting the meniscus shape of the ink in a nozzle, drying and thickening of an ink can be suppressed.

  In the media set sequence, the head heater 32 is turned off in all processes. As a result, it is possible to prevent the ink from drying and thickening during the execution of the sequence.

  Furthermore, in addition to the head heater 32, if the preheater 25, the platen heater 41, and the after heater 26 are also turned off, the effect of preventing ink drying and thickening can be enhanced. On the other hand, the pre-heater 25, the platen heater 41, and the after heater 26 may be controlled at a temperature lower than that at the time of image formation, and this can also suppress ink drying and thickening.

  In the present embodiment, the presence or absence of slight vibration and the on / off of the head heater 32, preheater 25, platen heater 41, and after heater 26 are adjusted according to the operating state of the ink jet printer 10, and preliminary ejection is performed. Execute. For this reason, it is not necessary to perform cleaning by sucking a large amount of ink, which is necessary when the ink is dried or thickened, so that the ink consumption can be suppressed. Further, since there is no time for such cleaning, productivity is increased, damage to the ink-jet head 31 due to cleaning can be reduced, and the life of the ink-jet head 31 can be extended.

  When an image is formed on a long medium M, a cleaning sequence is executed every time the medium M is conveyed by a predetermined length in order to ensure stable ink ejection. As described above, in the present embodiment, the head heater 32, the preheater 25, the platen heater 41, and the after heater 26 are turned on / off and whether or not there is slight vibration according to the operation state of the inkjet printer 10 during the execution of the cleaning sequence. Adjust. For this reason, it is possible to reliably maintain the ink ejection properties before and after the cleaning sequence, thereby improving the stability when image formation is continuously performed.

  Further, the control circuit 70 determines whether or not there is slight vibration, whether or not preliminary ejection is performed, and whether or not preliminary ejection is performed according to the temperatures of the feeding-side guide 21, the discharge-side guide 22, the inkjet head 31, the platen 40, and the casing of the inkjet printer 10. The frequency of the waveform, the number of discharges, on / off of the head heater 32, preheater 25, platen heater 41, and after heater 26, and the heating temperature of the head heater 32, preheater 25, platen heater 41, and after heater 26 can be set. preferable.

  For the inkjet head 31, the preset temperature is stored in the memory 71 in advance, and the preset temperature and the temperature measured by the temperature sensor 34 are compared. When the temperature is equal to or lower than the set temperature, it is preferable to execute only slight vibration.

  For members other than the inkjet head 31, a sensor for measuring the temperature or a sensor for measuring the ambient temperature in the inkjet printer 10 is provided, and the set temperature is stored in the memory 71 in advance, and measured by the set temperature and the sensor. When the measured temperature is higher than the temperature, both the fine vibration and the preliminary ejection are caused to be executed by the inkjet head 31. When the measured temperature is equal to or lower than the set temperature, only the fine vibration is preferably executed.

  Such control can further enhance the effect of preventing ink drying and thickening.

  Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment, and can be improved or changed within the scope of the purpose of the improvement or the idea of the present invention.

  As described above, the ink jet printer according to the present invention is useful for an ink jet printer that forms an image on a wide or long medium.

DESCRIPTION OF SYMBOLS 10 Inkjet printer 12 Main body 13 Fixed part 20 Medium conveyance mechanism 21 Feeding side guide 22 Discharge side guides 23a, 23b Conveying roller 24 Back plate 25 Preheater 26 After heater 30 Carriage 31 Inkjet head 32 Head heater 33 Carriage drive mechanism 34 Temperature sensor 35 Medium detection sensor 40 Platen 41 Platen heater 42, 43 Spit area 50 Wipe unit 51 Wiper 52 Drive mechanism 60 Cap unit 61 Cap 62 Lifting mechanism 63 Pump 64 Valve 70 Control circuit 71 Memory

Claims (12)

A medium transport mechanism for transporting the medium;
A heating mechanism for heating the medium being transported by the medium transport mechanism;
An inkjet head that forms an image by discharging ink to the medium;
An inkjet printer comprising:
An ink jet printer, further comprising: a control unit that causes the ink jet head to execute one or both of fine vibration and preliminary ejection according to an operation state of the ink jet printer. The operation state of the ink jet printer includes a media set sequence performed when the medium is set in the ink jet printer,
In the media set sequence, the thickness of the medium is measured at a plurality of positions by a medium detection sensor provided in a carriage on which the inkjet head is mounted.
The ink jet printer according to claim 1, wherein the control unit causes the slight vibration to be executed in the media set sequence. In the operation state of the inkjet printer,
A cleaning sequence for performing at least one of a suction step of sucking ink by bringing a cap into close contact with the nozzle surface of the inkjet head, and a wiping step of wiping off the ink of the nozzle surface by a blade;
In the cleaning sequence, the inkjet head and the cap are separated from each other except in the suction step,
The ink jet printer according to claim 1, wherein the control unit causes the fine vibration to be executed in a region where the ink jet head is scanned in the cleaning sequence.   4. The ink jet printer according to claim 2, wherein the control unit causes preliminary ejection to be performed in an area other than an image forming area in which an image is formed by the ink jet head. 5. The operation state of the inkjet printer includes an image forming state in which an image is formed by ejecting ink onto the medium,
The ink jet printer according to claim 1, wherein the control unit causes the preliminary ejection to be performed in an area other than an image forming area where an image is formed by the ink jet head in the image forming state. The operation state of the inkjet printer includes the temperature of the inkjet head, the temperature of the heating mechanism, or the housing temperature of the inkjet printer,
The control unit causes the inkjet head to perform both the fine vibration and the preliminary ejection when any one of these temperatures exceeds a predetermined temperature set for each, and these temperatures are both equal to or lower than a set temperature. The inkjet printer according to claim 1, wherein only the slight vibration is executed.   The inkjet printer according to claim 1, wherein the control unit stops the operation of the heating mechanism in an operation state other than the image forming state.   The medium transport mechanism includes a feeding side guide that guides the medium to an image forming area by the ink jet head, and a discharge side guide that guides the medium in the image forming area in a discharging direction, and the heating mechanism. The inkjet printer according to claim 1, further comprising heaters respectively provided on the feeding side guide and the discharge side guide.   The ink jet printer according to claim 1, further comprising a heater that heats the ink filled in the ink jet head to a predetermined temperature.   A cap unit that sucks ink in the ink jet head from the nozzle surface at both ends in the scanning direction of the ink jet head across an image forming area where an image is formed by the ink jet head, and a wipe unit that wipes the ink on the nozzle surface by a blade And an inkjet printer according to claim 3.   2. The ink jet printer according to claim 1, wherein the cap unit includes a solvent supply unit that supplies a solvent that dissolves ink used in the ink jet printer to the nozzle surface.   The preliminary ejection is performed at least one of an area between an image forming area where an image is formed by the inkjet head and the cap unit, and an area between the image forming area and the wipe unit. The inkjet printer according to 10.

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