JP2004042314A - Liquid ejector and its flushing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform flushing effectively when liquid is in an unevenly viscous state in the vicinity of a meniscus. <P>SOLUTION: The liquid ejector comprises a control means 6 performing flushing by operating a pressure generating element 73 to eject liquid (ink) from a nozzle opening 51.The control means 6 has a function 41 for judging the degree of thickening of liquid in the vicinity of a meniscus, a function 42 for deciding where the liquid is thickened unevenly in the vicinity of the meniscus, a function 43 for trembling the liquid in the vicinity of the meniscus if the liquid is thickened unevenly, and an uneven thickening-measures function 44 for performing flushing following to trembling. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid ejecting apparatus and a flushing method for the liquid ejecting apparatus, and more particularly, to a liquid ejecting apparatus and a liquid ejecting apparatus that can recover a liquid ejecting capability of a nozzle by ejecting a liquid having increased viscosity in the vicinity of a meniscus from a nozzle opening. Flushing method.
[0002]
[Prior art]
In an ink jet recording apparatus (liquid ejecting apparatus) such as an ink jet printer or a plotter, a recording head is moved along a main scanning direction and a recording paper (a type of printing recording medium) is moved along a sub scanning direction. By ejecting ink droplets (liquid droplets) from the nozzle openings of the recording head in conjunction with this movement, an image (character) is printed on recording paper. The ejection of the ink droplets is performed, for example, by expanding and contracting a pressure generating chamber communicating with the nozzle opening.
[0003]
Since the ink near the meniscus is exposed to air at the nozzle opening portion of such a recording head, the ink solvent (for example, water) evaporates gradually. Due to the evaporation of the ink solvent, the viscosity of the ink near the meniscus increases, and the image quality of the image recorded on the recording paper deteriorates. That is, when the viscosity of the ink near the meniscus increases and thickens, the ejected ink droplets are dragged by the thickened ink and fly in a direction deviated from the normal direction, or clogging of the nozzle may occur. Sometimes. For this reason, when printing an image (characters, etc.) on recording paper, it is very important to eliminate the viscosity increase of the ink near the meniscus. The “meniscus” is the free surface of the ink exposed at the nozzle opening.
[0004]
By performing operations such as "flushing" and "cleaning" to eliminate various inconveniences caused by thickening of the ink, the thickened ink is discharged from the nozzles and the ink droplet ejection capability of the nozzles is restored. It is widely done.
[0005]
"Flushing" is to restore the ink discharge capability of the nozzles by applying a drive signal irrelevant to print data to the piezoelectric vibrator, for example, and discharging the thickened ink around the nozzle openings before printing before printing. is there. The "cleaning" is performed when the above-mentioned "flushing" cannot sufficiently restore the ink discharge capability of the nozzle, and by applying a negative pressure to the nozzle with a suction pump, the inside of the nozzle or the pressure is reduced. This is to forcibly suction the thickened ink in the generation chamber or the like in advance.
[0006]
In cleaning, ink is forcibly sucked by a suction pump, so that the amount of ink consumed is larger than in flushing. Therefore, from the viewpoint of increasing the effective ink amount usable for printing and keeping the waste liquid volume small, it is preferable to recover the ink droplet ejection ability by flushing, and it is desired to perform flushing as effectively as possible. .
[0007]
In view of such circumstances, for example, in Japanese Patent Application Laid-Open No. 2000-117993, an ink jet recording apparatus capable of effectively executing flushing by finely vibrating the thickened ink near the nozzle opening before normal flushing. Has been proposed. According to this ink jet recording apparatus, it is possible to widen the range of thickening of ink in which the ink ejection ability can be restored only by flushing, and to increase the thickening of ink which could not be dealt with conventionally without cleaning. Can be dealt with by flushing.
[0008]
[Problems to be solved by the invention]
By the way, the viscosity of the ink in the vicinity of the meniscus gradually increases with the passage of time. In particular, the increase in the viscosity of the ink in a short period of time after the evaporation of the ink solvent has started is usually shown in FIGS. ) And (c). FIGS. 8A, 8B, and 8C are enlarged views of the nozzle opening, and are conceptual diagrams showing the progress of thickening of the ink near the meniscus at the nozzle opening.
[0009]
The ink in the vicinity of the meniscus in the nozzle opening 51 is composed of only the ink 50a that has not thickened before the ink solvent evaporates (see FIG. 8A). From the nozzle opening toward the center of the nozzle opening (see FIG. 8B). Finally, the entire meniscus is constituted by the ink 50b whose viscosity has been increased to a predetermined viscosity (see FIG. 8C).
[0010]
Thereafter, the viscosity of the ink further proceeds from the nozzle opening toward the inside of the nozzle.
[0011]
As described above, in the process of increasing the viscosity of the ink in a short period of time (for example, about 1 second to 15 minutes in a low humidity environment of 0 ° C. to 40 ° C.) after the evaporation of the ink solvent starts, the vicinity of the meniscus (See FIG. 8 (b)) in which the ink is composed of ink having non-uniform viscosity (non-uniform thickening of the ink near the meniscus in the initial stage of thickening). (See FIGS. 8 (a) and 8 (c)).
[0012]
When flushing is performed in a state in which the ink near the meniscus has non-uniform thickening, the viscosity of the ink may cause the meniscus to become unstable, for example, the meniscus may enter obliquely and deeply. There is not preferred. Also, when the ink ejected from the nozzle opening during flushing is dragged by the thickened ink 50b, the ink is not ejected in an appropriate direction from the nozzle opening, or bubbles are taken into the nozzle opening. There is.
[0013]
On the other hand, when the viscosity of the ink further increases from the above-mentioned non-uniform thickening state and the viscosity of the entire ink near the meniscus becomes substantially uniform, the behavior of the meniscus during flushing becomes relatively stable, Ink can be ejected from the opening in an appropriate direction. Therefore, in this case, the ink discharge capability of the nozzle can be appropriately restored only by flushing.
[0014]
When the viscosity of the ink further increases, flushing cannot sufficiently cope with it, and cleaning is required to restore the ink discharge capability of the nozzle.
[0015]
As described above, in order to recover the ink discharging ability of the nozzle deteriorated by the thickening of the ink by flushing, in addition to the case where the evaporation of the ink solvent progresses and the whole ink near the meniscus thickens, the ink near the meniscus also increases. It is necessary to perform appropriate flushing even when a part of the ink is thickened to be in an unevenly thickened state.
[0016]
The present invention has been made in consideration of the above-described circumstances, and performs effective flushing to discharge liquid from a nozzle even when the liquid near the meniscus is in an unevenly thickened state. An object of the present invention is to provide a liquid ejecting apparatus and a flushing method for the liquid ejecting apparatus, which can restore the ability.
[0017]
[Means for Solving the Problems]
The present invention is a liquid ejecting head that causes a pressure change in the liquid in the pressure generation chamber to discharge the liquid from the nozzle opening by a pressure generation element provided corresponding to the pressure generation chamber communicating with the nozzle opening, A liquid storage unit that stores the liquid supplied to the pressure generation chamber, and a control unit that performs the flushing by discharging the liquid from the nozzle opening by operating the pressure generation element. A thickening judgment function for judging the degree of thickening of the liquid near the meniscus at the nozzle opening; and a liquid thickening near the meniscus based on the degree of thickening of the liquid near the meniscus determined by the thickening judging function. A thickening state judgment function for judging whether or not a uniform thickening has occurred, and the liquid near the meniscus is unevenly thickened by the thickening state judgment function. When it is determined that the pressure generating element is operated, a minute pressure fluctuation is generated in the liquid in the pressure generating chamber, and the liquid near the meniscus is finely vibrated. A liquid ejecting apparatus, comprising: a non-uniform thickening countermeasure flushing function for performing flushing by operating the pressure generating element after microvibrating a nearby liquid.
[0018]
Here, the state where “non-uniform thickening” occurs in the liquid near the meniscus means that, of the liquid near the meniscus, only a part of the liquid is thicker than the other parts, and the entire liquid near the meniscus is It means a state having an uneven viscosity.
[0019]
The thickening determining function has a stop time measuring function for measuring a time during which printing is stopped, and the thickening state determining function includes a printing stop time measured by the stop time measuring function that is not a predetermined time. If the print stop time corresponds to the uniform thickening occurrence printing, it is preferable to determine that the liquid near the meniscus has uneven viscosity.
[0020]
The recording head further includes capping means for sealing the nozzle forming surface, and the thickening state determining function has a capping time measuring function for measuring a capping time during which the nozzle forming surface is sealed by the capping means. However, the thickening state determination function, when the capping time measured by the capping time measurement function corresponds to a predetermined non-uniform thickening state time, uneven thickening occurs in the liquid near the meniscus. It is preferable to determine that there is.
[0021]
When the control means determines that the liquid in the vicinity of the meniscus does not cause uneven thickening by the thickening state determination function, the control means operates the pressure generating element to perform flushing. It is preferable to further have a function.
[0022]
The state where “substantially uniform thickening” occurs in the liquid near the meniscus means that the entire liquid near the meniscus is thickening and the entire liquid near the meniscus has a substantially uniform viscosity, and the nozzle Means a state in which flushing is sufficient to remove the thickened liquid therein.
[0023]
The control means further has a liquid type determination function for determining the type of liquid near the meniscus, and the thickening state determination function considers the type of liquid determined by the liquid type determination function, It is preferable to determine whether or not the liquid has uneven viscosity.
[0024]
It is preferable that the pressure generating element is a piezoelectric vibrator, and that the piezoelectric vibration of the piezoelectric vibrator causes a pressure change in the pressure generating chamber.
[0025]
When the liquid near the meniscus is finely vibrated by the fine vibration function, the waveform of the driving voltage applied to the piezoelectric vibrator is a voltage held by the piezoelectric vibrator when the driving voltage is applied to the piezoelectric vibrator. It is preferable that the waveform starts from.
[0026]
It is preferable that the functions of the control unit are executed when the power of the liquid ejecting apparatus is turned on or when printing is started.
[0027]
The liquid discharged from the nozzle opening preferably contains a pigment.
[0028]
The present invention is a liquid ejecting head that causes a pressure change in the liquid in the pressure generation chamber to discharge the liquid from the nozzle opening by a pressure generation element provided corresponding to the pressure generation chamber communicating with the nozzle opening, A liquid storage unit that stores the liquid supplied to the pressure generation chamber, and in a flushing method of a liquid ejecting apparatus including: a thickening determination step of determining a degree of thickening of a liquid near a meniscus at the nozzle opening; A thickening state determining step of determining whether the liquid near the meniscus has undergone uneven thickening based on the degree of thickening of the liquid near the meniscus determined in the thickening determining step; When it is determined in the viscosity determination step that the liquid in the vicinity of the meniscus has undergone uneven thickening, the pressure generating element is operated to apply the liquid in the pressure generating chamber to the liquid in the pressure generating chamber. A micro-vibration step of causing small pressure fluctuations to finely vibrate the liquid near the meniscus, and, after finely vibrating the liquid near the meniscus in the micro-vibration step, operating the pressure generating element to perform a non-uniform A flushing method for a liquid ejecting apparatus, comprising: a thickening countermeasure flushing step.
[0029]
The thickening determining step includes a stop time measuring step of measuring a time during which printing is stopped, and the thickening state determining step includes determining that the printing stop time measured by the stop time measuring step is a predetermined time. If the print stop time corresponds to the uniform thickening occurrence printing, it is preferable to determine that the liquid near the meniscus has uneven viscosity.
[0030]
The liquid ejecting apparatus further includes a capping unit that seals a nozzle forming surface of the recording head, and the thickening state determination step measures a capping time during which the nozzle forming surface is sealed by the capping unit. The method further comprises a capping time measuring step, wherein the thickening state determining step includes the step of determining whether the capping time measured by the capping time measuring step corresponds to a predetermined non-uniform thickening state time. It is preferable to determine that a thickening has occurred.
[0031]
When it is determined in the thickening state determining step that the liquid in the vicinity of the meniscus does not cause uneven thickening, the method further includes a substantially uniform thickening countermeasure flushing step of operating the pressure generating element to perform flushing. Is preferred.
[0032]
The method further includes a liquid type determination step of determining a type of liquid in the vicinity of the meniscus, and the thickening state determination step includes determining whether the liquid in the vicinity of the meniscus is non-uniform in consideration of the type of liquid determined in the liquid type determination step. It is preferable to determine whether or not any thickening has occurred.
[0033]
It is preferable that the pressure generating element is a piezoelectric vibrator, and that the piezoelectric vibration of the piezoelectric vibrator causes a pressure change in the pressure generating chamber.
[0034]
When the liquid near the meniscus is finely vibrated in the fine vibration step, the waveform of the drive voltage applied to the piezoelectric vibrator is a voltage held by the piezoelectric vibrator when the drive voltage is applied to the piezoelectric vibrator. It is preferable that the waveform starts from.
[0035]
It is preferable that the respective steps of the control unit are executed when the power of the liquid ejecting apparatus is turned on or when printing is started.
[0036]
The liquid discharged from the nozzle opening preferably contains a pigment.
[0037]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0038]
FIG. 1 is a schematic block diagram illustrating a configuration of an ink jet recording apparatus according to an embodiment of the present invention. 2A and 2B are perspective views of the ink jet recording apparatus, in which FIG. 2A is a diagram illustrating a schematic configuration of the entire apparatus, FIG. 2B is a view of the linear encoder and the slit detector as viewed from above, and FIG. () Is a view of the linear encoder and the slit detector as viewed from the side. 3A and 3B are diagrams illustrating a recording head using a piezoelectric vibrator in a longitudinal vibration mode, wherein FIG. 3A is a diagram illustrating the overall schematic configuration, and FIG. 3B is an enlarged view of a nozzle opening. FIG. 4 is a block diagram illustrating an electrical configuration of the recording head. FIG. 5 is a schematic diagram illustrating each function of the control unit. FIG. 6 is a flowchart showing a series of operations up to the printing operation. FIG. 7 is a diagram illustrating an example of a micro-vibration drive voltage applied to the piezoelectric vibrator when the ink near the meniscus is micro-vibrated.
[0039]
The liquid ejecting apparatus according to the present embodiment is an ink jet recording apparatus (ink jet printer), and includes a printer controller 1 and a print engine 2 as shown in FIG.
[0040]
As shown in FIG. 1, the printer controller 1 includes an external interface 3 (external I / F), a RAM 4 for temporarily storing various data, a ROM 5 for storing a control program and the like, a CPU, and the like. Control unit (control means) 6, an oscillation circuit 7 for generating a clock signal, a drive signal generation unit 9 for generating a drive signal to be supplied to an ink jet recording head (liquid ejecting head) 8, a drive signal, printing An internal interface 10 (internal I / F) for transmitting dot pattern data (bitmap data) and the like developed based on the data to the print engine 2.
[0041]
Further, the printer controller 1 transmits the information recorded in the memory card 11 to the control unit 6, a memory card 11, which is a kind of a recording medium detachably held, a card slot 12 functioning as a recording medium holding unit. And a card interface 13 (card I / F). The memory card 11 records data on the waveform of the drive signal. As a recording medium other than the memory card 11, for example, a floppy disk, a hard disk, a magneto-optical disk, or the like can be used.
[0042]
The external I / F 3 receives, for example, print data including a character code, a graphic function, and image data from a host computer (not shown). In addition, a busy signal (BUSY) and an acknowledge signal (ACK) are output to a host computer or the like via the external I / F3.
[0043]
The RAM 4 has a reception buffer 4A, an intermediate buffer 4B, an output buffer 4C, a work memory, and (not shown). The reception buffer 4A temporarily stores the print data received via the external I / F 3, the intermediate buffer 4B stores the intermediate code data converted by the control unit 6, and the output buffer 4C stores the dot pattern. It is designed to store data. Here, the dot pattern data is print data obtained by decoding (translating) intermediate code data (for example, gradation data).
[0044]
The ROM 5 stores font data, graphic functions, and the like, in addition to a control program (control routine) for performing various data processing.
[0045]
The control unit 6 performs various controls according to a control program stored in the ROM 5. For example, the print data in the reception buffer 4A is read, and the print data is converted into intermediate code data, and the intermediate code data is stored in the intermediate buffer 4B. Further, the control unit 6 analyzes the intermediate code data read from the intermediate buffer 4B, and develops (decodes) the dot pattern data by referring to the font data and graphic functions stored in the ROM 5. I have. Then, after performing the necessary decoration processing, the control section 6 stores the dot pattern data in the output buffer 4C.
[0046]
When one line of dot pattern data recordable by one main scan of the ink jet recording head 8 is obtained, the dot pattern data of one line is sequentially transferred from the output buffer 4C to the ink jet recording head 10 through the internal I / F 10. The data is output to the recording head 8. When one line of dot pattern data is output from the output buffer 4C, the expanded intermediate code data is deleted from the intermediate buffer 4B, and the expansion processing for the next intermediate code data is performed.
[0047]
Further, as shown in FIG. 5, the control unit 6 includes an ink type determining function (liquid type determining function) 40, a thickening determining function 41, a thickening state determining function 42, a fine vibration function 43, and a non-uniform thickening countermeasure flushing. It has a function 44, a flushing function 45 for countermeasures for almost uniform thickening and a cleaning function 46. As will be described later, by executing these functions of the control section 6, flushing and cleaning are effectively performed, and a meniscus suitable for printing is formed at each nozzle opening 51.
[0048]
The drive signal generation unit 9 discharges a drive signal (discharge drive signal) for discharging ink from the nozzle opening 51 during printing or flushing, and finely vibrates ink near the meniscus to generate ink near the nozzle opening 51. And a driving signal for micro-vibration (micro-vibration driving signal) for stirring. Then, the drive signal generating section 9 can output a predetermined drive signal selected from the ejection drive signal and the fine vibration drive signal to the internal I / F.
[0049]
The drive signal generator 9 can be configured by a logic circuit or a control circuit configured by a CPU, a ROM 5, a RAM 4, and the like.
[0050]
On the other hand, the print engine 2 includes a carriage mechanism 16, a paper feed mechanism 17, and an ink jet recording head 8.
[0051]
As shown in FIGS. 2A to 2C, the carriage mechanism 16 is movably attached to the guide member 20 and can mount the ink jet recording head 8 and the ink cartridge 19 thereon. A timing belt 24 that is bridged between the driving pulley 22 and the driven pulley 23 and connected to the carriage 21, a pulse motor 25 that rotates the driving pulley 22, and that is parallel to the width direction (main scanning direction) of the recording paper 18. A linear encoder 27 installed in a printer housing 26 in a proper state, and a slit detector 29 attached to the carriage 21 and capable of detecting a plurality of slits 28 of the linear encoder 27.
[0052]
The linear encoder 27 of the present embodiment is a transparent thin plate member, and has slits 28 formed at a pitch of 360 dpi, as shown in FIG. The slit detector 29 can be configured by, for example, a photo interrupter.
[0053]
According to such a carriage mechanism 16, the operation of the pulse motor 25 causes the carriage 21 to reciprocate along the width direction (main scanning direction) of the recording paper 18, and accordingly, the inkjet mounted on the carriage 21. The type recording head 8 also moves along the main scanning direction. The movement of the carriage 21 is performed starting from the reference position on the home position side.
[0054]
Here, the home position is a position where the carriage 21 waits when printing is not performed for a long time, such as when the power is not turned on. In the present embodiment, a home position is provided at the right end in FIG. At this home position, a capping mechanism 30 that can seal the nozzle forming surface 52 formed on the ink jet recording head 8 is provided.
[0055]
On the other hand, the reference position is set to a position slightly to the left of the home position. Specifically, a reference position is set between the right edge of the recording paper 18 and the capping mechanism 30.
[0056]
When the carriage 21 moves, the slit detector 29 moves together with the carriage 21. Along with this movement, the slit detector 29 sequentially detects the plurality of slits 28 of the linear encoder 27 and outputs a pulse-like detection signal corresponding to the pitch of the slits 28. The control unit 6 recognizes the position of the ink jet recording head 8 based on the detection signal from the slit detector 29.
[0057]
More specifically, the control unit 6 resets the count value of the position counter in a state where the carriage 21 is located at the reference position, and outputs a rising pulse (detection) from the slit detector 29 output as the carriage 21 moves. Signal) and counts up the position counter each time a pulse is received. Thus, the count value of the position counter becomes head position information indicating the position of the carriage 21, that is, the scanning position of the ink jet recording head 8. Here, the position counter may be provided, for example, in a work memory (not shown) of the RAM 4, but the counter may be provided separately.
[0058]
Therefore, the linear encoder 27 and the slit detector 29 function as scanning position information output means. That is, information (detection signal) relating to the position of the ink jet recording head 8 is output by the linear encoder 27 and the slit detector 29 with the main scanning of the carriage 21 (ink jet recording head 8). The control unit 6 and the position counter (RAM 4) function as a scanning position holding unit. That is, the updated count value after updating the count value (head position information) of the position counter based on the detection signal from the slit detector 29 is held by the control unit 6 and the position counter (RAM4). It has become.
[0059]
The capping mechanism 30 provided at the home position seals the nozzle forming surface 52 of the ink jet recording head 8 when the ink jet recording head 8 mounted on the carriage 21 moves to the home position. And a closed space is formed between them. As described above, by sealing the nozzle forming surface 52 by the capping mechanism 30, the evaporation of the ink solvent from the meniscus in the nozzle opening 51 can be effectively prevented.
[0060]
A pump unit 31 is provided below the capping mechanism 30. The pump unit 31 is attached to the capping mechanism 30 via an ink discharge pipe (not shown) so that a negative pressure can be applied to the closed space formed by the nozzle forming surface 52 and the capping mechanism 30. Has become.
[0061]
A wiping unit 32 is provided near the recording area of the capping mechanism 30. The wiping means 32 is arranged so as to be able to advance and retreat in the horizontal direction with respect to the movement locus of the ink jet recording head 8, for example, and has an elastic plate such as rubber. The wiping unit 32 is configured to wipe the nozzle forming surface 52 of the ink jet recording head 8 as necessary when the carriage 21 reciprocates to the capping mechanism 30 side.
[0062]
The paper feed mechanism 17 includes a paper feed motor, a paper feed roller, and the like, and can sequentially feed the recording paper 18 in conjunction with the recording operation of the ink jet recording head 8. That is, the paper feed mechanism 17 can move the recording paper 18 in the sub-scanning direction of the recording paper 18.
[0063]
As shown in FIGS. 3A and 3B, the ink jet recording head 8 includes a piezoelectric vibrator 73 in a longitudinal vibration mode.
[0064]
That is, as shown in FIG. 3 (a), a comb-shaped piezoelectric vibrator 73 is inserted from one opening into a storage chamber 72 of a box-shaped case 71 made of plastic, for example, as shown in FIG. Then, the comb-like tip 73a faces the other opening. A channel unit 74 is joined to the surface (lower surface) of the case 71 on the other opening side, and each comb-shaped tip 73 a is fixed to a predetermined portion of the channel unit 74.
[0065]
The piezoelectric vibrator 73 is obtained by cutting a plate-shaped vibrator plate in which common internal electrodes 73c and individual internal electrodes 73d are alternately stacked with a piezoelectric body 73b interposed therebetween, in a comb-teeth shape corresponding to the dot formation density. It is configured. By applying a potential difference between the common internal electrode 73c and the individual internal electrode 73d, each piezoelectric vibrator 73 expands and contracts in the vibrator longitudinal direction orthogonal to the lamination direction.
[0066]
The channel unit 74 is configured by laminating a nozzle plate 76 and an elastic plate 77 on both sides with a channel forming plate 75 interposed therebetween.
[0067]
The flow path forming plate 75 communicates with the plurality of nozzle openings 51 formed in the nozzle plate 76, and the pressure generating chambers 81 are arranged in a row with the partition wall interposed therebetween. This is a plate member in which a plurality of ink supply units 82 communicating with one end and an elongated common ink chamber 83 communicating with all the ink supply units 82 are formed.
[0068]
For example, an elongated common ink chamber 83 is formed by etching a silicon wafer, and pressure generating chambers 81 are formed along the longitudinal direction of the common ink chamber 83 in accordance with the pitch of the nozzle openings 51. A groove-like ink supply unit 82 can be formed between the common ink chamber 81 and the common ink chamber 83. In this case, an ink supply section 82 is connected to one end of the pressure generating chamber 81, and the nozzle opening 51 is located near the end opposite to the ink supply section 82. Further, the common ink chamber 83 is a chamber for supplying the ink stored in the ink cartridge 19 (liquid storage section) to the pressure generating chamber 81, and an ink supply pipe 84 communicates with substantially the center in the longitudinal direction. ing. Note that, in addition to the black ink, color inks such as yellow, cyan, and magenta are stored in the ink cartridge 19, and each ink is supplied to the corresponding pressure generating chamber 81.
[0069]
The elastic plate 77 is laminated on the surface of the flow path forming plate 75 on the opposite side of the nozzle plate 76, and is formed by laminating a polymer film such as PPS as an elastic film 88 on the lower surface side of the stainless steel plate 87. It has a heavy structure. The stainless plate 87 corresponding to the pressure generating chamber 81 is etched to form an island portion 89 for abutting and fixing the piezoelectric vibrator 73.
[0070]
As described above, in the ink jet recording head 8 including the piezoelectric vibrator 73 in the longitudinal vibration mode, for example, by discharging the piezoelectric vibrator 73 and extending the piezoelectric vibrator 73 in the longitudinal direction of the vibrator, the island portion 89 becomes closer to the nozzle plate 76. , The elastic film 88 around the island portion 89 is deformed, and the pressure generating chamber 81 contracts. When the piezoelectric vibrator 73 is charged and contracted in the longitudinal direction from the contracted state of the pressure generating chamber 81, the pressure generating chamber 81 expands due to the elasticity of the elastic film 88. Then, by expanding and contracting the pressure generating chamber 81 once, the ink pressure in the pressure generating chamber 81 is increased, and the ink droplet 50c is ejected from the nozzle opening 51 (FIG. 3B). )reference). In this way, by expanding and contracting the pressure generating chamber 81 once, it is not necessary to particularly increase the magnitude of the driving voltage applied to the piezoelectric vibrator 73 when ejecting ink from the nozzle openings 51. For this reason, at the time of ink ejection, it is possible to prevent inconveniences such as the ink being rapidly drawn into the nozzle to deteriorate the meniscus, and taking in bubbles in the nozzle.
[0071]
Accordingly, the ink jet recording head 8 having such a configuration applies pressure to the ink in the pressure generation chamber 81 by the piezoelectric vibration of the piezoelectric vibrator 73 provided corresponding to the pressure generation chamber 81 communicating with the nozzle opening 51. The ink can be ejected from the nozzle openings 51 by causing the fluctuation. In addition, by appropriately selecting the magnitude and waveform of the drive voltage applied to the piezoelectric vibrator 73 and adjusting the piezoelectric vibration of the piezoelectric vibrator 73, the ink near the meniscus can be finely controlled without discharging the ink from the nozzle openings 51. It is also possible to vibrate.
[0072]
The electrical configuration of such an ink jet recording head 8 is configured as shown in FIGS.
[0073]
That is, as shown in FIG. 1, the inkjet recording head 8 includes a shift register 55, a latch circuit 56, a level shifter 57, a switch 58, and a piezoelectric vibrator 73 that are electrically connected in sequence. Further, as shown in FIG. 4, the shift register 55, the latch circuit 56, the level shifter 57, the switch 58, and the piezoelectric vibrator 73 are each provided with a shift register element 55A provided for each nozzle opening 51 of the recording head 8. To 55N, latch elements 56A to 56N, level shifter elements 57A to 57N, switch elements 58A to 58N, and piezoelectric vibrators 73A to 73N.
[0074]
The shift register 55, the latch circuit 56, the level shifter 57, the switch 58, and the control unit 6 function as a drive voltage supply unit. That is, a drive voltage is generated from a predetermined drive signal in the drive signal generator 9 and supplied to the piezoelectric vibrator 73 of the recording head 8.
[0075]
Next, referring to FIG. 5, an ink type determining function 40, a thickening determining function 41, a thickening state determining function 42, a fine vibration function 43, a non-uniform thickening countermeasure flushing function 44, a substantially uniform thickening The respective functions of the viscous measure flushing function 45 and the cleaning function 46 will be described.
[0076]
The ink type determination function 40 determines the type of ink near the meniscus in the nozzle opening 51.
[0077]
Generally, the type of ink supplied to each nozzle is often determined in advance. Accordingly, the ink type determination function 40 identifies each piezoelectric vibrator 73 and each nozzle corresponding to each piezoelectric vibrator 73, and detects the ink near the meniscus in each nozzle opening 51 from each of the identified piezoelectric vibrators 73 and each nozzle. The type is determined. The ink type determination function 40 can determine the type of ink in the vicinity of the meniscus in each nozzle opening 51 by another ink type determination method in addition to such an ink type determination method. For example, the ink type determination function 40 can also determine the type of ink in each nozzle based on a signal sent from the ink cartridge 19 mounted on the carriage 21, and can also determine the type of ink near the meniscus. It is also possible to separately install an ink detecting device for detecting the type, and determine the type of ink in each nozzle based on the detection result of the ink detecting device.
[0078]
The viscosity increase determination function 41 has a stop time measurement timer 47 (stop time measurement function) for measuring the time during which printing is stopped in order to determine the degree of viscosity increase of the ink near the meniscus in the nozzle opening 51. are doing.
[0079]
In general, the ink solvent gradually evaporates from the meniscus according to the time during which printing is stopped, so that the degree of thickening of the ink near the meniscus can be determined based on the time during which printing is stopped. . The viscosity increase determination function 41 determines the degree of viscosity increase of the ink near the meniscus by detecting the print stop time measured by the stop time measurement timer 47.
[0080]
The thickening state judging function 42 generates non-uniform thickening of ink near the meniscus based on the type of ink determined by the ink type determining function 40 and the print stop time detected by the thickening determining function 41. Is determined.
[0081]
That is, the thickened state determination function 42 determines which of flushing and cleaning is necessary to restore the ink discharge capability of each nozzle based on the print stop time measured by the stop time measurement timer 47. It has become.
[0082]
When it is determined that cleaning is necessary, the thickened state determination function 42 determines that excessive thickening, which cannot restore normal ejection performance by flushing, occurs in the ink near the meniscus. Then, each nozzle is cleaned by a cleaning function 46 described later.
[0083]
If it is determined that flushing is necessary and the print stop time measured by the stop time measuring timer 47 corresponds to the “predetermined non-uniform thickening occurrence print stop time”, the ink near the meniscus It is determined that non-uniform thickening has occurred. When the print stop time does not correspond to the “predetermined non-uniform thickening occurrence print stop time”, the thickening state determination function 42 determines that the ink near the meniscus has substantially uniform thickening. It has become.
[0084]
The determination as to which of flushing and cleaning is necessary, and the “predetermined non-uniform thickening occurrence print stop time” are determined according to the type of ink determined by the ink type determination function 40. It has become.
[0085]
The micro-vibration function 43 activates the piezoelectric vibrator 73 when the ink in the vicinity of the meniscus is determined to be in an unevenly thickened state by the thickened state determination function 42, and The ink in the vicinity of the meniscus is finely vibrated by causing a slight pressure fluctuation in the ink.
[0086]
That is, the micro-vibration function 43 supplies a driving voltage for micro-vibration based on the driving signal from the driving signal generator 9 to the piezoelectric vibrator 73 via the shift register 55, the latch circuit 56, the level shifter 57, and the switch 58. It is supposed to. By supplying the driving voltage for micro-vibration to the piezoelectric vibrator 73 as described above, the piezoelectric vibrator 73 is caused to generate piezoelectric vibration for micro-vibration, so that the ink near the meniscus can be micro-vibrated. Has become.
[0087]
The non-uniform thickening countermeasure flushing function 44 performs the flushing by operating the piezoelectric vibrator 73 after finely vibrating the ink near the meniscus by the fine vibration function 43.
[0088]
That is, the non-uniform thickening countermeasure flushing function 44 controls the shift register 55, the latch circuit 56, the level shifter 57, and the switch 58 based on the drive voltage for non-uniform thickening countermeasure flushing based on the drive signal from the drive signal generator 9. The piezoelectric vibrator 73 is supplied via the piezoelectric vibrator 73. As described above, by supplying the driving voltage for the non-uniform thickening countermeasure flushing to the piezoelectric vibrator 73, the piezoelectric vibrator 73 is caused to generate the piezoelectric vibration for the non-uniform thickening countermeasure flushing, thereby performing the flushing. Can be done.
[0089]
The substantially uniform thickening countermeasure flushing function 45 activates the piezoelectric vibrator 73 when the thickening state determination function 42 determines that the ink near the meniscus has substantially uniform thickening, thereby increasing the substantially uniform thickening. Viscosity countermeasure flushing is performed.
[0090]
That is, the substantially uniform thickening countermeasure flushing function 45 transmits the drive voltage for the substantially uniform thickening countermeasure flushing based on the drive signal from the drive signal generator 9 to the shift register 55, the latch circuit 56, the level shifter 57, and the switch 58. The piezoelectric vibrator 73 is supplied via the piezoelectric vibrator 73. As described above, by supplying the driving voltage for the substantially uniform thickening countermeasure flushing to the piezoelectric vibrator 73, the piezoelectric vibrator 73 is caused to generate the substantially uniform thickening countermeasure flushing piezoelectric vibration and the flushing is executed. Can be done.
[0091]
The cleaning function 46 is provided when the thickening state determination function 42 determines that the ink near the meniscus has excessively thickened which cannot restore the normal ejection ability by flushing. The nozzle forming surface 52 is sealed by the capping mechanism 30 to form a closed space between the nozzle forming surface 52 and the capping mechanism 30. Then, a negative pressure is applied to the closed space by the pump unit 31 to forcibly suck the thickened ink in the nozzle, the pressure generating chamber 81, and the like from the nozzle.
[0092]
In addition, the state where “non-uniform thickening” occurs in the ink near the meniscus means that only a part of the ink near the meniscus is thicker than the other parts, and the entire ink near the meniscus is not thick. It means a state having a uniform viscosity. Further, the state in which “substantially uniform thickening” occurs in the ink near the meniscus means that the entire ink near the meniscus has increased in viscosity and the entire ink near the meniscus has a substantially uniform viscosity. Means a state in which flushing for removing the thickened ink in the nozzle can sufficiently cope with it. Further, the state in which “excessive thickening” occurs in the ink near the meniscus means that the entire ink near the meniscus is thickening, and the ink near the meniscus has a substantially uniform viscosity. Means a state in which flushing cannot sufficiently cope with the ink in order to remove the thickened ink therein and needs to be coped with by cleaning.
[0093]
Next, the operation of the ink jet recording apparatus according to the present embodiment having such a configuration will be described.
[0094]
First, a specific printing operation on the recording paper 18 in the above-described ink jet recording apparatus will be described.
[0095]
The shift register 55, the latch circuit 56, the level shifter 57, the switch 58, and the control unit 6 function as drive voltage supply means, and a drive voltage is generated based on the drive signal generated by the drive signal generation unit 9, and the drive voltage is generated. It is supplied to the piezoelectric vibrator 73.
[0096]
The piezoelectric vibrator 73 is charged or discharged in accordance with the supplied drive voltage, and expands or contracts in the longitudinal direction of the vibrator to vibrate piezoelectrically. Pressure fluctuation occurs in the pressure generating chamber 81 in accordance with the piezoelectric vibration of the piezoelectric vibrator 73, and ink is ejected from the nozzle openings 51.
[0097]
For example, when the piezoelectric vibrator 73 is charged by the supplied driving voltage and contracts in the longitudinal direction, the pressure generating chamber 81 expands and the pressure in the chamber decreases. As a result, the meniscus in the nozzle opening 51 is slightly drawn toward the pressure generating chamber 81, and the predetermined ink stored in the ink cartridge 19 is newly supplied into the pressure generating chamber 81.
[0098]
When the piezoelectric vibrator 73 is discharged by the supplied driving voltage and extends in the longitudinal direction, the pressure generating chamber 81 contracts and the pressure in the chamber increases. Accordingly, the ink in the pressure generating chamber 81 is compressed, and the ink is ejected from the nozzle opening 51 in response to the compression.
[0099]
In this manner, by appropriately adjusting the magnitude, waveform, and the like of the drive voltage supplied to the piezoelectric vibrator 73, it is possible to control the ejection amount, ejection timing, and the like of the ink droplets from the nozzle openings 51. For this reason, by supplying an appropriate drive voltage to the piezoelectric vibrator 73 at an appropriate timing, desired ink can be ejected from the nozzle openings 51 and an image such as a character can be printed on the recording paper 18.
[0100]
Next, a series of operations until a new printing operation is performed when a new printing operation is performed in a state where the above-described printing operation has not been performed for a relatively long time will be described with reference to the flowchart of FIG. I do.
[0101]
For example, when a new printing operation is performed in a state where the printing operation has not been performed for a relatively long time, such as when power is turned on or when printing is started, a control unit is provided for each nozzle used in the new printing operation. After performing flushing or cleaning based on the functions of the printer 6, a specific printing operation is performed.
[0102]
That is, when a new printing operation is performed in a state where the printing operation has not been performed for a relatively long time, when a predetermined printing command is input to the control unit 6 (STEP 1), the stoppage time is determined by the viscosity increase determination function 41. The print stop time of each nozzle measured by the measurement timer 47 is detected (viscosity increase determination step) (STEP 2).
[0103]
The ink type determination function 40 determines the type of ink near the meniscus in each nozzle opening 51 (ink type determination step) (STEP 3). That is, the ink type determination function 40 identifies the ink in each nozzle by the above-described ink type determination method, and determines the type of ink near the meniscus in each nozzle opening 51.
[0104]
Then, the thickening state determining function 42 determines the vicinity of the meniscus in each nozzle opening 51 based on the type of ink determined by the ink type determining function 40 and the print stop time measured by the thickening determining function 41. It is determined whether non-uniform thickening of the ink has occurred (thickening state determining step) (STEP 4).
[0105]
At this time, the thickening state determination function 42 determines which of flushing and cleaning is necessary to restore the ink discharge capability of each nozzle based on the print stop time measured by the stop time measurement timer 47. (Step 5).
[0106]
When the thickening state determination function 42 determines that cleaning is necessary, it determines that the ink near the meniscus has excessively thickened.
[0107]
In addition, the thickening state determination function 42 is a case where it is determined that flushing is necessary, and the print stop time measured by the stop time measuring timer 47 corresponds to the “predetermined non-uniform thickening occurrence print stop time”. If the print stop time does not correspond to the "predetermined non-uniform thickening occurrence print stop time", it is determined that the ink near the meniscus has uneven viscosity. It is determined that substantially uniform thickening has occurred (STEP 6).
[0108]
The determination as to which one of flushing and cleaning is appropriate, and the “predetermined non-uniform thickening occurrence printing stop time” are determined according to the type of ink determined by the ink type determination function 40. It is determined by the state determination function 42. Therefore, even when various inks are used as in the case of color printing, the thickening state determination function 42 performs the thickening process in which the ink near the meniscus causes uneven thickening depending on the type of ink in each nozzle. In the initial stage, the ink in the vicinity of the meniscus may have a non-uniform thickening in consideration of the possibility that the ink ejection from each nozzle may be in an unstable state, the time zone in which the ink ejection is in an unstable state, etc. It is determined whether or not it has occurred. Thus, the thickening state determination function 42 can accurately determine whether uneven thickening, substantially uniform thickening, or excessive thickening has occurred, according to the type of ink in each nozzle.
[0109]
The micro-vibration function 43 performs a micro-vibration operation on the nozzles that have been determined by the viscous state determination function 42 as having caused the ink near the meniscus to have non-uniform thickening (step 7). .
[0110]
That is, a driving voltage for micro-vibration is applied to the piezoelectric vibrator 73 to cause the piezoelectric vibrator 73 to generate piezoelectric vibration, thereby causing a slight pressure fluctuation in the ink in the pressure generating chamber 81. At this time, a driving voltage is applied to the piezoelectric vibrator 73 so as to slightly vibrate the ink near the meniscus without discharging the ink from the nozzle opening 51. FIG. 7 shows an example of such a driving voltage for micro vibration. In FIG. 7, a solid line indicates a waveform of a driving voltage for micro-vibration, and a broken line indicates an example of a waveform of a driving voltage applied to the piezoelectric vibrator 73 when ink is ejected from the nozzle openings 51. As shown in FIG. 7, the driving voltage for micro-vibration has a lower potential than the driving voltage applied to the piezoelectric vibrator 73 when ink is ejected from the nozzle openings 51.
[0111]
It is preferable that the waveform of the driving voltage for micro-vibration applied to the piezoelectric vibrator 73 is a waveform starting from the voltage held by the piezoelectric vibrator 73 when the driving voltage is applied to the piezoelectric vibrator 73. By applying a drive voltage having such a waveform to the piezoelectric vibrator 73, it is possible to prevent a sudden change in the voltage applied to the piezoelectric vibrator 73, and to prevent rapid expansion and contraction of the piezoelectric vibrator 73. In addition, it is possible to prevent rapid pressure fluctuation in the pressure generating chamber 81. Accordingly, the behavior of the meniscus can be maintained in a stable state, and the ink near the meniscus can be finely vibrated in a state where the ink is not ejected from the nozzle openings 51.
[0112]
Thus, when the ink near the meniscus is finely vibrated by the fine vibration function 43, these inks are agitated, and the viscosity of the ink near the meniscus is made uniform.
[0113]
Then, in the nozzle in which the ink near the meniscus is finely vibrated by the fine vibration function 43, flushing is performed by the non-uniform thickening measure flushing function 44 (non-uniform thickening measure flushing step) (STEP 8).
[0114]
That is, by finely vibrating the ink in the vicinity of the meniscus to make the viscosity uniform, a driving voltage for flashing for non-uniform thickening is applied to the piezoelectric vibrator 73 to cause the piezoelectric vibrator 73 to generate piezoelectric vibration. Then, flushing is performed by discharging the thickened ink from the nozzle openings 51 (flushing for preventing uneven viscosity). This flushing is performed in a state in which the viscosity of the ink in the vicinity of the meniscus is substantially uniformized by the fine vibration, so that it is possible to prevent inconvenience at the time of flushing due to the difference in the viscosity of the ink. Further, flushing is effectively performed, and a meniscus suitable for printing can be efficiently formed.
[0115]
On the other hand, in the thickening state judging function 42, for a nozzle for which it is determined that non-uniform thickening of ink near the meniscus has occurred but substantially uniform thickening has occurred, substantially uniform thickening countermeasure flushing is performed. Flushing is performed by the function 45 (substantially uniform thickening countermeasure flushing step) (STEP 9).
[0116]
That is, by applying a drive voltage for flushing to substantially uniform viscosity increase to the piezoelectric vibrator 73 without causing the ink near the meniscus to vibrate finely, and causing the piezoelectric vibrator 73 to generate piezoelectric vibration, Flushing is performed by discharging the thickened ink (substantially uniform thickening countermeasure flushing). When the ink near the meniscus has a substantially uniform thickening, the viscosity of the ink near the meniscus is in a substantially uniform state. For this reason, even if the ink near the meniscus is not finely vibrated, the flushing is performed in a state where the viscosity of the ink near the meniscus is substantially uniform, so that inconvenience at the time of flushing due to the difference in the viscosity of the ink can be prevented. . In addition, the flushing makes it possible to print with fresh ink having a desired viscosity while excluding the thickened ink.
[0117]
On the other hand, in the thickening state determination function 42, cleaning is performed by the cleaning function 46 on the nozzles in which the ink near the meniscus has not been unevenly thickened but has been determined to have excessively thickened. Performed (cleaning step) (STEP 10).
[0118]
That is, the nozzle forming surface 52 of the ink jet recording head 8 is sealed by the capping mechanism 30 by the cleaning function 46, and a closed space is formed between the nozzle forming surface 52 and the capping mechanism 30. Then, a negative pressure is applied to the sealed space by the pump unit 31 to forcibly suck the thickened ink in the nozzle, the pressure generating chamber 81, and the like from the nozzle. As a result, the thickened ink is removed from the nozzle, and a meniscus suitable for printing is formed. As described above, even when the viscosity of the ink in the nozzle has excessively increased, the thickened ink is removed from the nozzle by cleaning, and the ink discharge capability of the nozzle is restored.
[0119]
As described above, when a new printing operation is performed in a state where the printing operation has not been performed for a relatively long time, the non-uniform thickening countermeasure flushing, the substantially uniform thickening countermeasure flushing, or the cleaning is performed as described above. At each nozzle, the thickened ink is removed to form a meniscus suitable for printing. Then, following the flushing operation or the cleaning operation, the above-described printing operation is performed, and an image such as a character is printed on the recording paper 18 (STEP 11).
[0120]
As described above, according to the present embodiment, when the meniscus is in an unevenly thickened state at the time of flushing, based on each function of the control unit 6, prior to the specific flushing operation, the vicinity of the meniscus is Is slightly vibrated. Thus, a specific flushing operation is performed in a state where the viscosity of the entire ink near the meniscus is substantially uniform, and the flushing can be performed effectively.
[0121]
As described above, by performing the flushing effectively, the number of ink droplets (the number of flushing shots) ejected at the time of flushing can be reduced, and the time required for restoring the ink ejection capability of the nozzle can be shortened. And the amount of ink ejected during flushing can be reduced. In addition, it is possible to prevent inconvenience caused by a difference in ink viscosity.For example, ink ejected during flushing may fly in a direction deviated from a normal direction, or bubbles may be taken into nozzles during flushing. It is possible to prevent such inconveniences as being lost and to perform appropriate flushing in a stable state.
[0122]
When the printing stop time is relatively long and the meniscus is in a substantially uniform thickening state during flushing, the viscosity of the entire ink in the vicinity of the meniscus is substantially uniform. Based on the functions described above, a specific flushing operation can be performed without finely vibrating the ink near the meniscus. As described above, since the flushing is performed in a state where the viscosity of the whole ink near the meniscus is substantially uniform, the flushing can be performed in a stable state. In addition, since a specific flushing operation is performed without finely vibrating the ink near the meniscus, it is possible to prevent the time required for a series of operations for restoring the ink discharge ability from being unnecessarily prolonged.
[0123]
By the way, the ink ejection operation and the micro-vibration operation of the ink near the meniscus fluctuate depending on the magnitude and waveform of the drive voltage applied to the piezoelectric vibrator 73. Therefore, by adjusting the magnitude and waveform of the drive voltage applied to the piezoelectric vibrator 73, the ink ejection behavior and meniscus behavior can be easily controlled.
[0124]
In addition, in the ink jet recording apparatus as described above, various types of ink such as pigment ink and dye ink can be ejected from the nozzle openings 51 in addition to various color inks. In particular, when the printing operation is not performed for a relatively long time, the pigment ink tends to thicken in the vicinity of the meniscus, and may adhere in a solid state at the nozzle opening 51 to hinder the ejection of the ink. However, even if the pigment ink near the meniscus has non-uniform viscosity, the pigment ink is slightly vibrated before the flushing operation based on the functions of the control unit 6 described above, so that the vicinity of the meniscus is reduced. The non-uniform thickening of the ink is eliminated and flushing can be performed effectively.
[0125]
The flushing or cleaning is performed in order to recover the ink discharge capability of the nozzle when the printing operation has not been performed for a relatively long time. Therefore, for example, when the power is turned on or when printing is started, the ink type determining function 40, the thickening determining function 41, the thickening state determining function 42, the fine vibration function 43, the non-uniform thickening countermeasure flushing function 44, and the substantially uniform It is preferable that each function such as the thickening countermeasure flushing function 45 and the cleaning function 46 can be performed. Since printing is not performed immediately before the power is turned on or when printing is started, there is a high possibility that the state where ink is not ejected from the nozzle openings 51 continues for a relatively long time when the power is turned on or printing is started. . Therefore, it is very effective to perform flushing or cleaning when the power is turned on or when printing is started.
[0126]
From the viewpoint of making the viscosity of the ink near the meniscus as uniform as possible, it is preferable that the ink near the meniscus be finely vibrated in as short a cycle as possible, so that the frequency of the voltage applied to the piezoelectric vibrator 73 is high. It is desirable that However, on the other hand, if the frequency of the voltage applied to the piezoelectric vibrator 73 is excessively high, the behavior of the meniscus becomes unstable, which may adversely affect the flushing operation and the printing operation after the fine vibration operation. Therefore, it is preferable that the frequency of the voltage applied to the piezoelectric vibrator 73 be high enough to keep the meniscus behavior stable.
[0127]
Next, a modified example of the above-described embodiment will be described.
[0128]
The viscosity increase determination function 41 of the control unit 6 measures the capping time during which the nozzle forming surface 52 of the ink jet recording head 8 is sealed by the capping mechanism 30 instead of the stop time measurement timer 47 (stop time measurement function). A capping time measuring timer (capping time measuring function) 48 may be provided.
[0129]
In this case, the thickening determining function 41 of the control unit 6 determines the degree of thickening of the ink near the meniscus by detecting the capping time of each nozzle measured by the stop time measuring timer 47. ing.
[0130]
Then, the thickening state determining function 42 of the control unit 6 determines the nozzle opening 51 based on the type of ink determined by the ink type determining function 40 and the capping time detected by the thickening determining function 41. It is determined whether or not the ink near the meniscus has uneven viscosity.
[0131]
Other configurations are substantially the same as the above-described embodiment. The same parts as those of the above-described embodiment are denoted by the same reference numerals, and detailed description is omitted.
[0132]
In the present modified example, when a new printing operation is performed in a state where the nozzle forming surface 52 of the ink jet recording head 8 is sealed for a relatively long time by the capping mechanism 30, the above-described viscosity increase determination step and ink type determination Steps such as a step, a thickening state determination step, a microvibration step, a non-uniform thickening countermeasure flushing step, a substantially uniform thickening countermeasure flushing step, and a cleaning step are performed.
[0133]
That is, when a new print operation is performed in a state where the nozzle forming surface 52 of the ink jet recording head 8 is sealed for a relatively long time by the capping mechanism 30, when a predetermined print command is input to the control unit 6, The thickening judgment function 41 detects the capping time of each nozzle measured by the capping time measuring timer 48 (thickening judgment step).
[0134]
Further, the ink type determination function 40 determines the type of ink near the meniscus in each nozzle opening 51 (ink type determination step).
[0135]
Then, the thickening state determining function 42 determines the ink in the vicinity of the meniscus in each nozzle opening 51 based on the type of ink determined by the ink type determining function 40 and the capping time measured by the thickening determining function 41. It is determined whether or not non-uniform thickening has occurred (thickening state determining step).
[0136]
At this time, based on the capping time measured by the capping time measuring timer 48, the thickened state determining function 42 determines which of flushing and cleaning is necessary to restore the ink discharge capability of each nozzle. .
[0137]
When the thickening state determination function 42 determines that cleaning is necessary, it determines that the ink near the meniscus has excessively thickened.
[0138]
In addition, the thickening state determination function 42 is a case where it is determined that flushing is necessary, and the capping time measured by the capping time measuring timer 48 corresponds to the “predetermined non-uniform thickening state time”. Determines that the ink near the meniscus has non-uniform thickening, and if the capping time does not correspond to the “predetermined non-uniform thickening state time”, the ink near the meniscus has substantially uniform thickening. Is determined to have occurred.
[0139]
The determination as to which of the flushing and the cleaning is appropriate, and the “predetermined non-uniform thickening state time” are determined according to the type of ink determined by the ink type determining function 40. Determined by function 42. Therefore, even when various inks are used as in the case of color printing, the thickening state determination function 42 performs the non-uniform thickening, the substantially uniform thickening, or the excessive thickening according to the type of ink in each nozzle. The presence or absence of stickiness can be reliably determined.
[0140]
The micro-vibration function 43 performs a micro-vibration operation on the nozzles that have been determined by the thickening state determination function 42 as having caused the ink near the meniscus to have non-uniform thickening.
[0141]
Then, in the nozzle in which the ink near the meniscus is finely vibrated by the fine vibration function 43, flushing is performed by the non-uniform thickening countermeasure flushing function 44 (non-uniform thickening countermeasure flushing step).
[0142]
On the other hand, in the thickening state judging function 42, for a nozzle for which it is determined that non-uniform thickening of ink near the meniscus has occurred but substantially uniform thickening has occurred, substantially uniform thickening countermeasure flushing is performed. Flushing is performed by the function 45 (substantially uniform thickening countermeasure flushing step).
[0143]
On the other hand, in the thickening state determination function 42, cleaning is performed by the cleaning function 46 on the nozzles in which the ink near the meniscus has not been unevenly thickened but has been determined to have excessively thickened. (Cleaning process).
[0144]
As described above, when a new printing operation is performed in a state where the nozzle forming surface 52 of the ink jet recording head 8 is sealed by the capping mechanism 30 for a relatively long time, the non-uniform thickening countermeasures are performed as described above. Flushing, substantially uniform thickening countermeasure flushing, or cleaning is performed. At each nozzle, the thickened ink is removed, and a meniscus suitable for printing is formed. Then, following the flushing operation or the cleaning operation, the above-described printing operation is performed, and an image such as a character is printed on the recording paper 18.
[0145]
As described above, also in this modification, when the meniscus is in a non-uniformly thickened state at the time of flushing, similar to the present embodiment, a specific Prior to the flushing operation, the ink near the meniscus is slightly vibrated. Thus, the entire ink in the vicinity of the meniscus has a substantially uniform viscosity and a specific flushing operation is performed, so that flushing can be performed effectively.
[0146]
In addition, when the capping time is relatively long and the ink near the meniscus has a substantially uniform thickening during flushing, the viscosity of the entire ink near the meniscus is substantially uniform. Based on each function of the unit 6, a specific flushing operation is performed without finely vibrating the ink near the meniscus. Therefore, flushing can be performed in a stable state, and the time required for a series of operations for restoring the ink discharge capability can be prevented from being unnecessarily prolonged.
[0147]
Although the recording head 8 using the piezoelectric vibrator 73 in the longitudinal vibration mode as a pressure generating element has been illustrated in the above-described embodiment and its modifications, other pressure generating elements may be used. For example, a piezoelectric vibrator in a flexural vibration mode can be used.
[0148]
The flexural vibration mode piezoelectric vibrator is a piezoelectric vibrator that fluctuates the pressure in the pressure generating chamber by using the bending of the piezoelectric vibrator attached to the outer wall of the pressure generating chamber, and is described in, for example, Japanese Patent Application Laid-Open No. 2001-260369. Flexural mode piezoelectric vibrators of the type disclosed are contemplated.
[0149]
A recording head that uses a piezoelectric vibrator in the flexural vibration mode applies a predetermined drive voltage to the piezoelectric vibrator to perform charging and discharging, and deflects the piezoelectric vibrator. By bending the piezoelectric vibrator in this manner, the outer wall of the pressure generating chamber is pressed by the piezoelectric vibrator, and the pressure in the pressure generating chamber is fluctuated.
[0150]
Even when the recording head in the flexural vibration mode is used, the same effects as those in the above-described embodiment and its modifications can be obtained.
[0151]
In the above-described embodiment and its modifications, the printer controller 1 is constituted by a computer system.
[0152]
Further, it is also possible to use a program for realizing each of the functions of the control unit 6 by a computer system, or a computer-readable recording medium storing the program.
[0153]
Further, when each of the functions of the control unit 6 is realized by a program such as an OS running on a computer system, a program including various instructions for controlling the program of the OS or the like, or a computer-readable program storing the program It is also possible to use a possible recording medium.
[0154]
In the above-described embodiment and the modifications thereof, the example in which the present invention is applied to the ink jet recording apparatus has been described, but the present invention is not limited to this. The present invention relates to, for example, a color material ejecting head used for producing a color filter such as a liquid crystal display, an electrode material ejecting head used for forming an electrode such as an organic EL display and an FED, and a biological organic matter ejecting head used for producing a biochip. , Etc. can be applied to a liquid ejecting apparatus having a liquid ejecting head.
[0155]
【The invention's effect】
As described above, according to the present invention, it is determined whether the liquid near the meniscus has non-uniform thickening, and it is determined that the liquid near the meniscus has non-uniform thickening. Before the flushing is performed, the liquid near the meniscus is slightly vibrated.
[0156]
Thereby, even if the entire liquid near the meniscus has non-uniform viscosity due to non-uniform thickening, the viscosity of the liquid near the meniscus is made uniform by the micro vibration, and the non-uniform thickening occurs. Flashing is performed in a state where the state has been eliminated. Therefore, even when the liquid near the meniscus has an uneven viscosity, the flushing can be effectively performed, and the liquid discharge capability of the nozzle can be restored.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram illustrating a configuration of an ink jet recording apparatus according to an embodiment of the present invention.
FIGS. 2A and 2B are perspective views of an ink jet recording apparatus, FIG. 2A is a diagram showing a schematic configuration of the entire apparatus, FIG. 2B is a view of a linear encoder and a slit detector as viewed from above, and FIG. () Is a view of the linear encoder and the slit detector as viewed from the side.
3A and 3B are diagrams illustrating a recording head using a piezoelectric vibrator in a longitudinal vibration mode, wherein FIG. 3A is a diagram illustrating a schematic configuration of the whole, and FIG. 3B is an enlarged view of a nozzle opening portion.
FIG. 4 is a block diagram illustrating an electrical configuration of the recording head.
FIG. 5 is a schematic diagram showing functions of a control unit.
FIG. 6 is a flowchart showing a series of operations up to a printing operation in the ink jet recording apparatus.
FIG. 7 is a diagram illustrating an example of a driving voltage for micro-vibration applied to a piezoelectric vibrator when ink near a meniscus is micro-vibrated.
FIG. 8 is a diagram illustrating a thickened state of ink forming a meniscus at a nozzle opening.
[Explanation of symbols]
1 Printer controller
2 Print engine
6 control unit
8 Recording head
16 Carriage mechanism
17 Paper feed mechanism
18 Recording paper
19 Ink cartridge
20 Guide member
21 carriage
30 Capping mechanism
31 Pump unit
40 Ink type judgment function
41 Thickening judgment function
42 Thickening state judgment function
43 Micro vibration function
44 Non-uniform viscosity increase flushing function
45 Flushing function for almost uniform thickening
46 Cleaning Function
47 Stop time measurement timer
48 Capping time measurement timer
50a, 50b, 50c ink
51 Nozzle opening
52 Nozzle forming surface
73 Piezoelectric vibrator

Claims (18)

A liquid ejecting head that causes a pressure change in the liquid in the pressure generating chamber to discharge the liquid from the nozzle opening, by a pressure generating element provided corresponding to the pressure generating chamber communicating with the nozzle opening;
A liquid storage unit that stores the liquid supplied to the pressure generation chamber,
By operating the pressure generating element, control means for performing a flushing by discharging a liquid from the nozzle opening,
The control means includes:
A thickening determination function for determining the degree of thickening of the liquid near the meniscus at the nozzle opening,
Based on the degree of thickening of the liquid near the meniscus determined by the thickening determination function, a thickening state determining function to determine whether uneven thickening has occurred in the liquid near the meniscus,
When it is determined that the liquid near the meniscus is unevenly thickened by the thickening state determination function, the pressure generating element is operated to cause a slight pressure fluctuation in the liquid in the pressure generating chamber. A micro-vibration function for micro-vibrating the liquid near the meniscus
A liquid ejecting apparatus comprising: a non-uniform thickening countermeasure flushing function for performing flushing by operating the pressure generating element after finely vibrating a liquid in the vicinity of a meniscus by the fine vibration function. The thickening determination function has a stop time measurement function to measure the time during which printing is stopped,
The thickening state judging function, when the printing stop time measured by the stop time measuring function corresponds to a predetermined non-uniform thickening occurrence printing stop time, uneven thickening of the liquid near the meniscus. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is determined to have occurred. The recording head further comprises capping means for sealing a nozzle forming surface,
The thickening state determination function has a capping time measurement function of measuring a capping time in which the nozzle forming surface is sealed by the capping unit,
The thickening state determination function, when the capping time measured by the capping time measurement function corresponds to a predetermined non-uniform thickening state time, that uneven liquid thickening near the meniscus has occurred. The liquid ejecting apparatus according to claim 1, wherein the determination is performed. The control means operates the pressure-generating element to perform flushing when the liquid in the vicinity of the meniscus does not cause uneven thickening by the thickening state determination function. The liquid ejecting apparatus according to claim 1, further comprising a function. The control means further has a liquid type determination function of determining the type of liquid near the meniscus,
The said thickening state judging function considers the kind of liquid judged by the liquid kind judging function, and judges whether or not the liquid near the meniscus has uneven thickening. Item 5. The liquid ejecting apparatus according to any one of Items 1 to 4. The liquid according to any one of claims 1 to 5, wherein the pressure generating element is a piezoelectric vibrator, and a pressure fluctuation is generated in the pressure generating chamber by a piezoelectric vibration of the piezoelectric vibrator. Injection device. When the liquid near the meniscus is finely vibrated by the fine vibration function, the waveform of the driving voltage applied to the piezoelectric vibrator is a voltage held by the piezoelectric vibrator when the driving voltage is applied to the piezoelectric vibrator. 7. The liquid ejecting apparatus according to claim 6, wherein the waveform starts from The liquid ejecting apparatus according to claim 1, wherein each of the functions of the control unit is executed when a power of the liquid ejecting apparatus is turned on or when printing is started. The liquid ejecting apparatus according to any one of claims 1 to 8, wherein the liquid discharged from the nozzle opening contains a pigment. A liquid ejection head that causes a pressure change in the liquid in the pressure generation chamber to discharge the liquid from the nozzle opening by a pressure generation element provided corresponding to the pressure generation chamber communicating with the nozzle opening; and the pressure generation chamber. A liquid storage unit that stores the liquid supplied to the liquid ejecting apparatus, comprising:
Thickening determination step of determining the degree of thickening of the liquid near the meniscus at the nozzle opening,
Based on the degree of thickening of the liquid near the meniscus determined in the thickening determination step, a thickening state determining step of determining whether or not the liquid near the meniscus has undergone uneven thickening,
When it is determined in the thickening determination step that the liquid in the vicinity of the meniscus is unevenly thickened, the pressure generating element is operated to cause a slight pressure fluctuation in the liquid in the pressure generating chamber. A micro-vibration step of micro-vibrating the liquid near the meniscus
After finely vibrating the liquid in the vicinity of the meniscus in the fine vibration step, the pressure generating element is operated, and a non-uniform thickening countermeasure flushing step of performing flushing is performed,
A flushing method for a liquid ejecting apparatus, comprising: The thickening determination step has a stop time measurement step of measuring the time during which printing is stopped,
In the thickening state determination step, when the printing stop time measured by the stop time measuring step corresponds to a predetermined non-uniform thickening occurrence printing stop time, uneven thickening of the liquid near the meniscus occurs. The flushing method according to claim 10, wherein it is determined that the flushing has occurred. The liquid ejecting apparatus further includes capping means for sealing a nozzle forming surface of the recording head,
The thickening state determining step includes a capping time measuring step of measuring a capping time in which the nozzle forming surface is sealed by the capping unit,
In the thickening state determination step, when the capping time measured by the capping time measuring step corresponds to a predetermined non-uniform thickening state time, it is determined that non-uniform thickening has occurred in the liquid near the meniscus. The flushing method according to claim 10, wherein the determination is performed. If it is determined in the thickening state determining step that the liquid in the vicinity of the meniscus does not cause uneven thickening, the method further includes a substantially uniform thickening countermeasure flushing step of operating the pressure generating element to perform flushing. The flushing method according to any one of claims 10 to 12, wherein: Further comprising a liquid type determination step of determining the type of liquid near the meniscus,
The thickening state judging step judges whether or not the liquid in the vicinity of the meniscus has non-uniform thickening in consideration of the type of the liquid judged in the liquid type judging step. 14. The flushing method according to any one of items 10 to 13. The flushing device according to any one of claims 10 to 14, wherein the pressure generating element is a piezoelectric vibrator, and the pressure fluctuation is generated in the pressure generating chamber by the piezoelectric vibration of the piezoelectric vibrator. Method. When the liquid near the meniscus is finely vibrated in the fine vibration step, the waveform of the drive voltage applied to the piezoelectric vibrator is a voltage held by the piezoelectric vibrator when the drive voltage is applied to the piezoelectric vibrator. The flushing method according to claim 15, wherein the waveform starts with the following. 17. The flushing method according to claim 10, wherein each of the steps is performed when a liquid ejecting apparatus is turned on or when printing is started. The flushing method according to any one of claims 10 to 17, wherein the liquid discharged from the nozzle opening contains a pigment.

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