JP2012192669A - Device and method for ejecting liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid ejecting device that can eliminate failure ejection and clogging caused by desiccation of the liquid in a nozzle that does not eject the liquid for a long period of time by injecting minimum droplets even during an ejecting operation, and to provide a method for ejecting liquid.SOLUTION: In the liquid ejecting device, a nozzle 11a provided in a liquid ejection head 10 as an arbitrary first nozzle required for drawing, ejects an ink droplet 14a when drawing an image to a recording medium 13, wherein a nozzle 11b as a second nozzle that does not eject ink ejects an ink droplet 14b having an ink amount smaller than an ink weight required for drawing.

Description

  The present invention relates to a liquid ejecting apparatus such as an ink jet printer, and a liquid ejecting method in the liquid ejecting apparatus.

  The liquid ejecting apparatus is an apparatus that includes a liquid ejecting head capable of ejecting liquid and ejects various liquids from the liquid ejecting head. A typical example of the liquid ejecting apparatus includes an ink jet recording head (hereinafter simply referred to as a recording head) as a liquid ejecting head, and liquid ink is applied from a nozzle of the recording head to a recording medium such as a recording sheet (landing). An image recording apparatus such as an ink jet printer (hereinafter simply referred to as a printer) that records an image or the like by jetting and landing on an object.

  In the above-described printer, in a nozzle that does not eject ink for a long time, the viscosity of the ink may increase or the ink in the nozzle may harden, and the nozzle may become clogged. As a result, normal ink droplets cannot be ejected, or even if ejected, the ejection direction is not stable, and the landing position on the recording medium is displaced. In order to solve such problems, conventionally, for example, as described in Patent Document 1, the recording head is moved from the printing area to the non-printing area during a period other than the printing operation, By supplying the mist from the mist generating means formed independently of the recording head and the cap to the closed space formed by the nozzle and the cap in a state where the cap is in contact with the nozzle surface, the nozzle An ink jet recording apparatus that prevents the drying of the ink is known.

JP 2008-207514 A

  However, in the liquid ejecting apparatus described in Patent Document 1, it is necessary to include a cap and a mist generating device in order to prevent the nozzle from drying. In addition, since the drying is prevented by supplying the mist to the closed space after the cap is brought into contact with the nozzle surface, the operation is limited to a period other than the liquid droplet ejection (for example, printing) operation on the recording medium. Accordingly, the start of the next droplet ejection onto the recording medium is delayed at least by the time for executing the operation. Furthermore, since the mist is supplied to the entire closed space composed of the cap and the nozzle, the mist is supplied to the nozzle capable of ejecting normal ink droplets. There was a problem.

  The present invention can solve the problem that nozzles that have not been jetted cause abnormal jetting or clogging due to liquid drying, without the need for a dedicated dry prevention device, and with the minimum required droplet jetting. An object of the present invention is to provide a liquid ejecting apparatus and a liquid ejecting method in the liquid ejecting apparatus.

  Application Example 1 A liquid ejecting apparatus according to this application example is a liquid ejecting apparatus including a liquid ejecting head that ejects liquid droplets from a nozzle opening toward a recording medium, and is driven by a drive signal generating unit. A first nozzle configured to land a predetermined droplet amount on the recording medium based on a signal, and a droplet having a smaller amount than the droplet ejected from the first nozzle; A second nozzle configured to eject the liquid droplets to the first nozzle, and when ejecting the liquid droplets from the first nozzle, a smaller amount of liquid droplets than the liquid droplets ejected from the first nozzle Injecting from the second nozzle.

According to this application example, since the amount of liquid droplets ejected from the second nozzle is smaller than the amount of liquid droplets ejected from the first nozzle, the viscosity of the liquid increases due to drying of the second nozzle. In this way, normal droplets can always be ejected from the second nozzle.
Therefore, it is possible to provide a liquid ejecting apparatus having a nozzle that does not cause abnormal ejection due to liquid drying or clogging.
Further, since the liquid droplet ejecting operation of the second nozzle is performed when the liquid droplet is ejected from the first nozzle, it does not require an excessive time until the next ejection start.

  Application Example 2 In the liquid ejecting apparatus according to the application example described above, the amount of droplets ejected from the second nozzle does not land on the recording medium, or the landing quality is improved even when landed. It is preferable that the amount of liquid droplets does not affect.

  According to this application example, since the droplet ejected from the second nozzle is set not to land on the recording medium, the contamination of the recording medium caused by the droplet ejected from the second nozzle is reduced. Can be suppressed.

  Application Example 3 In the liquid ejecting apparatus according to the application example described above, when a plurality of nozzles that do not eject a predetermined droplet amount are set on the recording medium based on the drive signal supplied from the drive signal generating unit. When the droplets are ejected from the first nozzle, the second nozzle that ejects a smaller amount of droplets than the droplets ejected from the first nozzle is the first nozzle. It is preferable that it is a nozzle arrange | positioned next to a nozzle.

  According to this application example, the partition between the pressure chamber upstream of the first nozzle and the pressure chamber upstream of the second nozzle is compared with the case where the adjacent nozzle of the first nozzle is not ejected. On the other hand, the force input from the piezoelectric vibrator provided in each pressure chamber acts in the opposite direction around the partition when the piezoelectric vibrator is deformed in the same phase. Since the deformation energy of the child is efficiently transmitted to the liquid in the pressure chamber, it is possible to suppress a drop in the droplet weight and flying speed of the first nozzle.

  Application Example 4 In the liquid ejecting apparatus according to the application example described above, a nozzle that does not eject a predetermined droplet amount onto the recording medium based on a drive signal supplied from the drive signal generation unit is the previous time of the nozzle. An elapsed time measuring means for measuring whether or not a predetermined time has elapsed from the ejection end time of the nozzle, and a nozzle that does not eject the predetermined droplet amount when ejecting a droplet from the first nozzle, Ejection determining means for determining whether to use as the second nozzle for ejecting a droplet having a smaller droplet amount than the droplet ejected from the first nozzle, based on a signal from the elapsed time measuring means And may be provided.

  In the liquid ejecting apparatus according to the application example, when a predetermined time has elapsed from the previous ejection end time of the second nozzle in the second nozzle, the liquid ejected from the first nozzle from the drive signal generating unit By supplying the second nozzle with a drive signal for ejecting a droplet having a smaller amount of droplets than the droplet, using the minimum amount of liquid, ejection failure or clogging due to thickening of the second nozzle can be prevented. Can be prevented.

  Application Example 5 In the liquid ejecting apparatus according to the application example described above, the ejection determination unit includes a liquid droplet in a nozzle used as the second nozzle based on a drive signal supplied from the drive signal generation unit. The injection start time and the injection end time may be determined according to the operating temperature environment.

  In the liquid ejecting apparatus described in the application example described above, it is possible to more accurately determine the ejection start time and the ejection end time of the liquid droplet according to the temperature environment by determining the ejection time.

  Application Example 6 A liquid ejection method according to this application example is a liquid ejection method in which droplets are ejected from a nozzle opening toward a recording medium, and a predetermined droplet amount is applied to the recording medium based on a drive signal. A first nozzle configured to land on the recording medium, and a second nozzle configured to eject a smaller amount of droplets onto the recording medium than droplets ejected from the first nozzle; When the droplets are ejected from the first nozzle, a smaller amount of droplets than the droplets ejected from the first nozzle are ejected from the second nozzle.

According to this application example, since the amount of liquid droplets ejected from the second nozzle is smaller than the amount of liquid droplets ejected from the first nozzle, the viscosity of the liquid increases due to drying of the second nozzle. In this way, normal droplets can always be ejected from the second nozzle.
Therefore, it is possible to provide a liquid ejecting apparatus having a nozzle that does not cause abnormal ejection due to liquid drying or clogging.
Further, since the liquid droplet ejecting operation of the second nozzle is performed when the liquid droplet is ejected from the first nozzle, it does not require an excessive time until the next ejection start.

FIG. 6 is a perspective view illustrating a configuration of a printing unit in the liquid ejecting apparatus. FIG. 3 is a cross-sectional perspective view of a main part showing a configuration of a liquid ejecting head. The block diagram which shows the structure of the control system which drives a liquid ejecting apparatus. The figure which shows the relationship between progress of non-ejection time, and ink viscosity. Schematic which shows an example of an inkjet recording device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the scale of each layer and each member is made different from the actual scale so that each layer and each member can be recognized. In the following, an ink jet recording apparatus will be described as an example of the liquid ejecting apparatus of the invention.

(Embodiment 1)
FIG. 1 is a perspective view illustrating a configuration of a printing unit in the liquid ejecting apparatus according to the present embodiment. FIG. 2 is a cross-sectional perspective view of a main part showing the configuration of the liquid jet head in FIG. FIG. 3 is a block diagram illustrating a configuration of a control system that drives the liquid ejecting apparatus.

  The liquid ejecting apparatus draws an arbitrary image on the recording medium 13 by ejecting ink droplets from the nozzles 11 provided in the liquid ejecting head 10 and landing them on arbitrary positions on the recording medium 13. The ink ejection timing and ejection amount are determined by the control unit 30 installed inside the liquid ejecting apparatus, and an electric signal is supplied to a drive signal generating circuit 31 as a drive signal generating unit. The drive signal generation circuit 31 generates a drive signal corresponding to the amount of ink ejected, and applies the drive signal to the piezoelectric vibrator 20 to deform the piezoelectric vibrator 20. Then, as the piezoelectric vibrator 20 is deformed, the pressure chamber upper wall 24 is bent as shown by a dotted line in FIG. 2, and the ink is pushed out from the nozzle 11 to eject ink droplets. . After the ink droplets are ejected, when the pressure chamber upper wall 24 returns to its original shape, an amount of ink corresponding to the ink pushed to the outside is supplied into the pressure chamber 21 from the supply port 23, and the nozzle 11 can be filled with ink to prepare for the ejection of the next ink drop.

  When the image is drawn on the recording medium 13, the ink droplet 14 a is ejected from the nozzle 11 a as an arbitrary first nozzle necessary for the drawing among the nozzles 11 provided in the liquid ejecting head 10. While the ink droplet 14a is being ejected from the nozzle 11a, the nozzle 11b as the second nozzle that does not eject ink is not protected from drying of the ink by the drying preventing member such as the cap 12. Therefore, the nozzle 11b is exposed to the outside air. Accordingly, the ink is dried in the nozzle 11b. Therefore, while the ink droplet 14a is being ejected from the nozzle 11a, by ejecting an ink amount smaller than the ink weight necessary for drawing to the nozzle 11b that does not eject ink having the ink weight necessary for drawing, It is possible to prevent a discharge failure that occurs when the ink of the nozzle 11b is dried. Accordingly, normal ink droplets can be ejected when the nozzle 11b functions as the first nozzle necessary for drawing, that is, when a drive signal is supplied.

However, in order to prevent the nozzle 11b from drying, if ink droplets having a droplet weight necessary for drawing and a necessary flying speed are ejected from the nozzle 11b, there is a possibility of landing on the recording medium. As a result, the print image formed by the ink droplets 14a ejected from the nozzle 11a is greatly affected.
In the present embodiment, for this problem, for example, when the ink droplet 14b ejected from the nozzle 11b is 3.6 ng or less and the velocity of the ink droplet is 4.0 m / s or less, the ink droplet 14b is ejected from the nozzle 11b. Before the ink droplet 14b is landed on the recording medium 13, it loses its momentum in the straight direction due to evaporation of the ink components and air resistance, so that it does not land on the recording medium 13, and therefore the landing quality, that is, the printing quality. Will not be affected. Of course, this numerical value is not limited to the numerical value described above. In other words, the droplet weight and the flying speed are changed according to the distance from the ejection surface of the liquid ejecting head 10 to the landing target.

  Incidentally, as shown in FIG. 2, when the nozzle 11b as the nozzle adjacent to the nozzle 11a for ejecting the drawing ink is not ejected, the pressure chamber upper wall 24a is deformed by the deformation of the piezoelectric vibrator 20a corresponding to the nozzle 11a. To do. On the other hand, the pressure chamber upper wall 24b adjacent to the pressure chamber upper wall 24a and corresponding to the piezoelectric vibrator 20b is not deformed. Therefore, the partition wall 22 between the pressure chambers receives an external force that deforms toward the pressure chamber 21a. As a result, a part of the deformation energy of the piezoelectric vibrator 20a is consumed for the deformation of the partition wall 22, so that the weight of the ink droplet ejected from the nozzle 11a and the flying speed are reduced. As a result, there is a possibility that the ink droplet does not land at a desired landing position.

  In the present embodiment, in order to solve this problem, when the nozzle 11b as the nozzle adjacent to the nozzle 11a ejects an ink amount smaller than the ink weight necessary for drawing at substantially the same timing as the nozzle 11a, the pressure chamber upper wall 24a and The external force input from 24b to the partition wall 22 acts in the opposite direction around the partition wall 22. For this reason, the amount of deformation of the partition wall is reduced, and the deformation energy of the piezoelectric vibrator 20a is efficiently transmitted to the ink in the pressure chamber 21a, so that the weight and speed of the ink droplets ejected from the nozzle 11a are reduced. Can be suppressed.

(Embodiment 2)
The liquid ejecting apparatus according to the present embodiment has the same configuration as the liquid ejecting apparatus according to the first embodiment described above, but the function content in the control unit 30 in FIG. 3 is different.

  As shown in FIG. 4, in the second nozzle, the ink viscosity in the nozzle due to drying increases exponentially with the passage of the non-ejection time. That is, when the non-ejection time is equal to or greater than the ejection start time Ts in FIG. 4, the ink viscosity of the second nozzle exceeds the upper limit viscosity that can be normally ejected. It becomes impossible to inject.

  Therefore, in the present embodiment, the control unit 30 in FIG. 3 has the function contents of the elapsed time measuring means and the injection determining means. Based on the drive signal supplied from the drive signal generation circuit 31, the elapsed time measuring means is configured such that a nozzle that does not eject a predetermined droplet amount to the recording medium 13 has passed a predetermined time from the previous ejection time of the nozzle. Measure whether or not. Further, the ejection determining unit ejects the nozzle that does not eject the predetermined droplet amount from the first nozzle when ejecting the droplet from the first nozzle based on the signal from the elapsed time measuring unit. It is determined whether or not to use as a second nozzle that ejects a droplet having a smaller droplet amount than the droplet to be discharged.

  The non-injection time of the nozzle 11b is counted by the control unit 30 by the elapsed time measuring unit and the injection determination unit, and when the injection start time Ts is reached, the control unit 30 passes the drive signal generation circuit 31 to the nozzle 11b. A drive signal is supplied until the injection end time Te. Therefore, it is possible to prevent ejection failure and clogging due to an increase in the viscosity of the nozzle 11b with the minimum necessary ink ejection amount.

(Embodiment 3)
In the present embodiment, in addition to the above-described second embodiment, the use environment temperature of the liquid ejecting head 10 is monitored by the temperature sensor 32 of FIG. 3, so that the optimum ejection start time Ts for increasing the ink viscosity according to the temperature environment. , And the injection end time Te are determined by the control unit 30.

  The ink jet liquid ejecting head of each of the above embodiments constitutes a part of a recording head unit including an ink flow path communicating with an ink cartridge or the like, and is mounted on the ink jet recording apparatus. FIG. 5 is a schematic view showing an example of the ink jet recording apparatus.

  As shown in FIG. 5, in the recording head units 41a and 41b having the ink jet recording head, cartridges 42a and 42b constituting ink supply means are detachably provided. The carriage 43 on which the recording head units 41 a and 41 b are mounted is provided on a carriage shaft 45 attached to the apparatus main body 44 so as to be movable in the axial direction. For example, the recording head units 41a and 41b eject a black ink composition and a color ink composition, respectively.

  The driving force of the driving motor 46 is transmitted to the carriage 43 through a plurality of gears and timing belt 47 (not shown), so that the carriage 43 on which the recording head units 41a and 41b are mounted is moved along the carriage shaft 45. The On the other hand, the apparatus main body 44 is provided with a platen 48 along the carriage shaft 45, and the recording medium 13, which is a recording medium such as paper fed by a not-shown paper feed roller, is wound around the platen 48. It is designed to be transported.

  In the first, second, and third embodiments described above, the ink jet recording head has been described as the liquid ejecting head. However, the present invention is widely intended for all liquid ejecting heads and ejects liquids other than ink. Of course, the invention can also be applied to a liquid jet head. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (field emission displays). Examples thereof include an electrode material ejection head used for electrode formation, a bioorganic matter ejection head used for biochip production, and the like.

  DESCRIPTION OF SYMBOLS 10 ... Liquid ejecting head, 11a, 11b ... Nozzle, 12 ... Cap, 13 ... Recording medium, 14 ... Ink droplet, 20, 20a, 20b ... Piezoelectric vibrator, 21a, 21b ... Pressure chamber, 22 ... Partition, 23 ... Supply port, 24a, 24b ... pressure chamber upper wall, 30 ... control unit, 31 ... drive signal generation circuit, 32 ... temperature sensor, 41a, 41b ... recording head unit, 42a, 42b ... cartridge, 43 ... carriage, 44 ... device Main body 45 ... carriage shaft 46 ... drive motor 47 ... timing belt 48 ... platen

Claims (6)

A liquid ejecting apparatus including a liquid ejecting head that ejects liquid droplets from a nozzle opening toward a recording medium,
Based on a drive signal supplied from the drive signal generating means, a first nozzle configured to land a predetermined droplet amount on the recording medium, and a droplet ejected from the first nozzle A second nozzle configured to eject a small amount of liquid droplets onto the recording medium,
When ejecting liquid droplets from the first nozzle, the liquid ejecting apparatus ejects a smaller amount of liquid droplets than the liquid droplets ejected from the first nozzle from the second nozzle. The liquid ejecting apparatus according to claim 1,
A liquid ejecting apparatus, wherein the droplets ejected from the second nozzle have a droplet amount that does not land on the recording medium, or a droplet amount that does not affect landing quality even when landed. The liquid ejecting apparatus according to claim 1 or 2,
When a plurality of nozzles that do not eject a predetermined droplet amount are set on the recording medium based on a drive signal supplied from the drive signal generation unit, and when a droplet is ejected from the first nozzle In addition, the liquid ejecting apparatus, wherein the second nozzle that ejects a smaller amount of liquid droplets than the liquid ejected from the first nozzle is a nozzle disposed adjacent to the first nozzle. The liquid ejecting apparatus according to any one of claims 1 to 3,
Based on the drive signal supplied from the drive signal generating means, a nozzle that does not eject a predetermined droplet amount to the recording medium measures whether a predetermined time has elapsed from the previous ejection end time of the nozzle. The elapsed time measuring means, and when ejecting droplets from the first nozzle, a nozzle that does not eject the predetermined droplet amount is set to a smaller amount of liquid than the droplets ejected from the first nozzle. A liquid ejecting apparatus comprising: an ejection determining unit that determines whether to use the second nozzle that ejects a droplet based on a signal from the elapsed time measuring unit. The liquid ejecting apparatus according to claim 4,
The ejection determining means determines, based on the driving temperature supplied from the driving signal generating means, the ejection start time and ejection end time of the liquid droplets in the nozzle used as the second nozzle based on the operating temperature environment. Liquid ejector. A liquid ejecting method for ejecting liquid droplets from a nozzle opening toward a recording medium,
Based on the drive signal, the first nozzle configured to land a predetermined droplet amount on the recording medium, and the droplet having a smaller amount than the droplet ejected from the first nozzle is recorded. A second nozzle configured to spray onto the medium,
A liquid ejecting method, wherein when ejecting droplets from the first nozzle, a smaller amount of droplets is ejected from the second nozzle than droplets ejected from the first nozzle.

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