JP2005288765A - Liquid ejector and cleaning method of liquid ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejector which can set a negative pressure releasing time by a viscosity of a liquid, and to provide a cleaning method of a liquid ejector. <P>SOLUTION: There are set a liquid jetting head 30 with a nozzle face for jetting the liquid; a liquid storage part 9, etc. which store the liquid; a liquid passage 20A, etc. for feeding the liquid from the liquid storage part 9, etc. to the liquid jetting head 30; a suction device 11 for sucking the liquid from the liquid jetting head 30 by contacting the nozzle face; a viscosity decision means 47 for deciding the viscosity of the liquid; and a standby time determining means 48 for determining on the basis of the viscosity of the liquid a standby time after the suction device 11 stops the suction of the liquid before an air pressure in the suction device 11 becomes nearly equal to an atmospheric pressure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid ejecting apparatus that ejects liquid and a cleaning method for the liquid ejecting apparatus.

  As a liquid ejecting apparatus that ejects liquid onto a target, an ink jet recording apparatus that performs printing by ejecting ink droplets from a recording head onto a recording medium is known. Such an ink jet recording apparatus records an image such as a desired character or graphic by ejecting minute ink droplets from a nozzle of a recording head onto a recording medium.

An ink jet recording apparatus includes an ink jet recording head that receives ink supplied from an ink cartridge, and a paper feeding unit that moves the recording paper relative to the recording head. Recording is performed by ejecting ink droplets onto the recording paper while moving in the direction.
For example, a black recording head that discharges black ink and a color recording head that can discharge yellow, cyan, and magenta inks are mounted on a common carriage. Full color printing is made possible by changing the ink ejection ratio.

In such an ink jet recording apparatus, a cleaning process, which is a forced ink discharge process, is performed in order to eliminate clogging of the recording head. This cleaning process is performed by bringing a cap into contact with the recording head and generating a negative pressure in the cap with a suction pump to forcibly eject ink from the recording head. After the cleaning is completed, the contact of the cap with the recording head is released after the passage of time until the atmospheric pressure in the cap becomes equal to the atmospheric pressure (negative pressure release time) (for example, Patent Document 1).
JP 2001-58421 A (FIG. 5 etc.)

However, the negative pressure release time described above varies depending on the viscosity of the ink. For example, when the ink viscosity increases, the negative pressure release time also increases. Therefore, when a short negative pressure release time corresponding to a low viscosity ink is applied even though the ink viscosity is high and a long negative pressure release time is required, for example, the cap remains in the cap while the negative pressure remains. When the contact with the recording head is released, there is a problem that the meniscus of the nozzle may be broken due to a sudden negative pressure change to cause a printing failure.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a liquid ejecting apparatus and a liquid ejecting apparatus cleaning method that can solve the above-described problems and can set a negative pressure release time based on various liquid viscosities.

  According to the first aspect, the object is to provide a liquid ejecting head having a nozzle surface for ejecting liquid, a liquid storage section storing the liquid, and supplying the liquid from the liquid storage section to the liquid ejecting head. A liquid passage, a suction device that contacts the nozzle surface and sucks the liquid from the liquid ejecting head, viscosity determination means that determines the viscosity of the liquid, and the suction device stops sucking the liquid. And a waiting time determining means for determining a waiting time until the atmospheric pressure in the suction device becomes substantially equal to the atmospheric pressure based on the viscosity of the liquid.

According to the configuration of the first aspect of the invention, the standby time that is the negative pressure release time is determined according to the viscosity of the liquid.
For this reason, for example, when the viscosity of the ink is high and a long negative pressure release time is required, a long negative pressure release time is applied, and when the ink viscosity is low and a short negative pressure release time is sufficient, a short negative pressure is required. Pressure release time can be applied.
Thereby, the negative pressure release time can be set by the viscosity of the liquid. Furthermore, the ink after the suction can be processed on the basis of the optimum negative pressure release time with respect to various inks whose viscosity is unknown as well as ink whose viscosity has increased due to thickening or the like.

  According to a second aspect of the present invention, in the configuration of the first aspect, the viscosity determination unit includes a bubble intake unit that takes bubbles into a liquid passage that supplies the liquid from the liquid storage unit to the liquid ejecting head, and the bubbles are Moving speed measuring means for measuring a moving speed of moving in the liquid passage, and determining the viscosity of the liquid based on speed viscosity information indicating a relationship between the moving speed and the viscosity of the liquid. To do.

According to the configuration of the second aspect of the invention, the liquid ejecting apparatus takes bubbles into the liquid passage by the bubble taking means, and measures the moving speed at which the bubbles move through the liquid passage by the moving speed measuring means.
The bubble moves in the liquid passage as the liquid is sucked and moved by the liquid suction means. That is, the moving speed of the bubbles is approximately equal to the moving speed of the liquid. This means that the moving speed of the bubbles represents the moving speed of the liquid.

The liquid ejecting apparatus determines the viscosity of the liquid based on speed viscosity information indicating a relationship between the moving speed and the viscosity of the liquid.
The moving speed and the viscosity of the liquid have a relationship that the moving speed becomes slower as the viscosity becomes higher. This means that the viscosity can be determined by the moving speed.
Therefore, if the moving speed is measured, the viscosity of the liquid can be determined based on the speed viscosity information.
Thereby, since the viscosity of the liquid in the liquid passage can be directly measured, an accurate negative pressure release time (the waiting time) can be set.

  According to a third invention, in the configuration of the second invention, the liquid suction means has a negative pressure generating means for sucking the liquid by applying a negative pressure, and the moving speed measuring means is the bubble The moving speed is measured by the number of operations of the negative pressure generating means during the period from the passage of the first reference point of the liquid passage to the passage of the second reference point.

  According to the configuration of the third invention, since the negative pressure generating means of the liquid suction means, for example, the number of operations of the suction pump, for example, the moving speed is measured by the number of rotations of the drive motor of the suction pump, The moving speed can be reliably measured by counting the number of rotations.

  According to a fourth invention, in the configuration of the third invention, the moving speed measuring means detects whether or not the bubble has passed the first reference point and the second reference point by an optical sensor. And

According to the configuration of the fourth invention, the moving speed measuring means detects whether or not the bubble has passed the first reference point and the second reference point by the optical sensor. Can be detected directly. As described above, since the movement of the bubbles is interlocked with the movement of the liquid, directly detecting the movement state of the bubbles means directly detecting the movement state of the liquid.
As described above, since the viscosity of the liquid can be determined based on the moving speed of the liquid, it is possible to directly measure the viscosity of the liquid.

  In a fifth aspect based on any one of the first to fourth aspects, the waiting time determining means is based on viscosity waiting time information indicating a relationship between the viscosity and the waiting time of the liquid suction means. The waiting time is determined.

Since the liquid flows until the negative pressure in the cap becomes equal to the atmosphere in the suction means, the waiting time varies depending on the viscosity of the liquid. That is, if the viscosity is high, it is necessary to lengthen the waiting time, and if the viscosity is low, the waiting time may be short.
In this regard, according to the configuration of the fifth aspect of the invention, based on the viscosity standby time information indicating the relationship between the viscosity and the standby time, that is, according to the viscosity of the liquid, an appropriate negative pressure release time (the standby time) Time) can be determined.

  According to the sixth aspect of the present invention, the liquid ejecting apparatus that ejects the liquid sucks the liquid, and the viscosity determining suction step, and the liquid ejecting apparatus determines the viscosity of the liquid. A standby time determining step for determining a standby time until the air pressure in the suction device becomes substantially equal to the atmospheric pressure based on the viscosity. Achieved by the cleaning method.

  According to the configuration of the sixth invention, similarly to the first invention, the negative pressure release time can be set by the viscosity of the liquid.

  According to a seventh aspect of the invention, in the configuration of the sixth aspect of the invention, in the viscosity determination step, the liquid ejecting apparatus supplies a liquid to the liquid ejecting head from the liquid storage unit that stores the liquid. A bubble taking-in step for taking in bubbles, a moving speed measuring step in which the liquid ejecting apparatus measures a moving speed at which the bubbles move in the liquid passage, and a relationship between the moving speed and the viscosity of the liquid. A viscosity information acquisition step of acquiring viscosity information of the liquid based on velocity viscosity information indicating

  According to the configuration of the seventh invention, similarly to the second invention, the viscosity of the liquid in the liquid passage can be directly measured, so that an accurate negative pressure release time (the waiting time) can be set. .

  In an eighth aspect based on the seventh aspect, the liquid suction means includes negative pressure generation means for applying a negative pressure to the liquid for suction, and in the moving speed measurement step, the bubble The moving speed is measured by the number of operations of the negative pressure generating means during the period from the passage of the first reference point of the liquid passage to the passage of the second reference point.

  According to the configuration of the eighth invention, as in the third invention, the moving speed depends on the number of rotations of the drive motor, for example, the number of operations of the suction pump, for example, the negative pressure generating unit of the liquid suction unit. Therefore, the moving speed can be reliably measured by counting the number of rotations.

  A ninth invention is characterized in that, in the configuration of the eighth invention, in the moving speed measuring step, it is detected by an optical sensor whether or not the bubble has passed through the first reference point and the second reference point. And

  According to the structure of 9th invention, the viscosity of the said liquid can be measured directly similarly to 4th invention.

  According to a tenth aspect of the present invention, in any one of the seventh to ninth aspects, the method includes a bubble discharging step of discharging the bubbles after the waiting time determining step.

If the bubbles taken into the liquid passage in the bubble taking-in step are left in the liquid passage as they are, it may obstruct the ejection of the liquid from the liquid ejecting head.
In this regard, according to the configuration of the tenth invention, since the bubbles are discharged, it is possible to prevent the problem that the liquid ejection may be obstructed.

Preferred embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows an ink jet recording apparatus 10 which is a preferred embodiment of the liquid ejecting apparatus of the present invention. The ink jet recording apparatus 10 is a so-called off-carriage recording apparatus in which an ink cartridge and a recording head are connected by an ink supply tube.
The ink jet recording apparatus 10 illustrated in FIG. 1 is an example of a liquid ejecting apparatus as described above, but the ink jet recording apparatus 10 includes a main body 10A. The main body 10A includes a carriage 1, a carriage motor 2, a timing belt 3, a scanning guide member 4, a paper transport mechanism unit 5, a cartridge holder 8, an ink suction device 11, and a wiping member 12.

The carriage 1 holds a recording head 30. The carriage 1 is attached to the timing belt 3. The timing belt 3 is moved endlessly by the carriage motor 2. Accordingly, the carriage 1 can be reciprocated along the main scanning direction T via the timing belt 3 by driving the carriage motor 2. This main scanning direction T is the paper width direction which is the longitudinal direction of the paper transport mechanism section 5.
The paper transport mechanism unit 5 is a mechanism for transporting paper, which is an example of a target medium that ejects ink, in a direction perpendicular to the main scanning direction T. The recording head 30 faces the sheet conveyed by the sheet conveying mechanism unit 5. The recording head 30 is an example of a liquid ejecting head having a nozzle surface that ejects liquid, and is also called a print head or a print head.

The cartridge holder 8 shown in FIG. 1 holds, for example, four ink cartridges 9A, 9B, 9C, 9D. The ink cartridges 9A, 9B, 9C, and 9D are examples of a liquid storage unit that stores liquid. Various inks used in the ink jet recording apparatus 10 are examples of liquids.
In the example of FIG. 1, four ink cartridges are mounted on the cartridge holder 8, but this number is not particularly limited.
For example, the ink cartridge 9A stores black ink, and the ink cartridge 9B stores yellow ink. The ink cartridge 9C stores magenta ink, and the ink cartridge 9D stores cyan ink.

The ink cartridges 9A to 9D have, for example, the following structure. Each ink cartridge 9A to 9D accommodates an ink pack formed of a flexible material in which ink is sealed.
Pressurized air generated by the pressurizing pump 21 is supplied into the ink cartridges 9A, 9B, 9C, and 9D via the connection passages 27A, 27B, 27C, and 27D via the pressure adjusting valve 22H and the pressure detector 23. it can. Any one or more of the ink cartridges 9A to 9D to which the pressurized air is supplied can send the ink in the ink pack inside thereof to the tubes 20A, 20B, 20C, and 20D through the ink supply valve 26. .

These tubes 20 </ b> A, 20 </ b> B, 20 </ b> C, and 20 </ b> D are examples of liquid passages that supply ink to the recording head 30. The tubes 20A to 20D are tubes of the same material and the same diameter, for example, and the cross section is preferably circular. The tubes 20A to 20D are translucent, for example.
Since the tubes 20A to 20D are thus translucent, the ink supplied from the tube can be visually recognized from the outside, and bubbles can be detected through light when the bubble detection sensor described later is optical. .
The tubes 20A to 20D are made of a flexible material. The upstream end side of the tubes 20A to 20D is connected to the ink supply valve 26. The downstream end side of the tubes 20A to 20D is connected to the recording head 30.

Next, the bubble intake valve group 12, the first bubble detection sensor group 201, and the second bubble detection sensor group 202 shown in FIG. 1 will be described.
The tubes 20A to 20D have, for example, a bubble intake valve group 12 which is a bubble intake means for taking bubbles into the tube 20A and the like, and the tube intake valve A and the like are released for a certain period of time, for example, 3 seconds. Air bubbles can be taken into 20A or the like. The bubble intake valve group 12 includes bubble intake valves 12A to 12D.

The tubes 20A and the like are moving speed measuring means for measuring the moving speed at which the bubbles taken in by the bubble intake valves 12 move through the tubes 20A and the like. For example, the first bubble detecting sensor group 201 and the second bubble detecting sensor. A group 202 is arranged.
The first bubble detection sensor group 201 includes bubble detection sensors 201A to 201D. The second bubble detection sensor group 202 includes bubble detection sensors 202A to 202D.
The bubble intake valve group 12 is in a position close to the upstream end side of the tube. The second bubble detection sensor group 202 is located closest to the recording head 30. The first bubble detection sensor group 201 is located between the first bubble intake valve group 12 and the second bubble detection sensor group 202.

2 and 3 are schematic views showing the configuration and the like of the first bubble detection sensor 201A.
The ink cartridges 9A to 9D have the same configuration, the tubes 20A to 20D have the same configuration, the first bubble detection sensors 201A to 201D have the same configuration, and the second bubble detection sensors 202A to 202D have the same configuration. Therefore, the ink cartridge 9A, the tube 20A, the first bubble detection sensor 201A, and the second bubble detection sensor 202A will be described, respectively, and the description of the other ink cartridge 9B and the like will be omitted.
As described above, the bubble intake valve 12A in FIG. 2 can take bubbles into the ink tube 20A by opening it for 1 second, for example.

The bubble detection sensors 201A and 202A are the same, for example, optical sensors. The bubble detection sensor includes a light emitting unit 400 and a light receiving unit 401. The light emitting unit 400 can use, for example, a light emitting diode, and the light receiving unit 401 can use a photodiode.
Light 400 </ b> L emitted from the light emitting unit 400 in FIG. 3 can be received by the light receiving unit 401. When the light receiving unit 401 receives the light 400L of the light emitting unit 400 and the bubble H passes through the bubble detection sensor along the ink supply direction L, a detection waveform 402 shown in FIG. It is supposed to be.

  That is, as shown in FIG. 2, the bubble H introduced by the bubble intake valve 12A is the first reference point that is the position of the tube 20A corresponding to the position of the first bubble detection sensor 201A and the first reference point as shown in FIG. The first bubble detection sensor 201A and the second bubble detection sensor 202A, which are optical sensors, determine whether or not the second reference point that is the position of the tube 20A corresponding to the reference point and the position of the second bubble detection sensor 202A is passed. It comes to detect. The first reference point and the second reference point are separated by a distance d in FIG. 2 corresponding to the position of the first bubble detection sensor group 201 and the position of the second bubble detection sensor group 202.

  As described above, the tube 20A or the like is a passage for ink that is a liquid, but the optical first bubble detection sensor group 201 and the second bubble detection sensor group 202 are used for measuring the moving speed of the bubble H. Therefore, it is desirable that the tube 20A or the like is made of a material that is translucent or transparent enough to optically detect bubbles in the ink.

  As described above, the bubble intake valve group 12 is released to take in bubbles from the outside, and the bubbles are detected by using the first bubble detection sensor group 201 and the second bubble detection sensor group 202 to detect the bubbles. Can be measured.

The ink suction device 11 and the wiping member 12 shown in FIG. 1 are arranged in a non-printing area (also called a home position) HP with respect to the main scanning direction T of the carriage 1.
The ink suction device is also called a capping device, and is an example of a liquid suction unit that contacts the nozzle surface of the recording head 30 and sucks ink such as the recording head 30 and the tube 20A. The ink suction device 11 has a cap body 13. The cap body 13 is made of a flexible material that can be sealed by contacting the nozzle plate surface of the recording head 30. When the carriage 1 moves to the non-printing area HP, the cap body 13 follows this to seal the nozzle plate surface of the recording head 30.

The ink suction device 11 functions as a lid that prevents the nozzle opening from being dried by sealing the nozzle plate surface of the recording head 30 during a period in which the ink jet recording device 10 is at rest. The ink suction device 11 can perform a cleaning operation for sucking and discharging ink from the nozzle openings on the nozzle plate surface of the recording head 30 by applying a negative pressure by a suction pump described later.
The wiping member 12 shown in FIG. 1 is made of an elastic material such as rubber. When the recording head 30 has moved to the home position HP, the wiping member 12 can be cleaned by mechanically wiping (wiping) the nozzle plate surface of the recording head 30.

Reference is now made to FIG. FIG. 4 shows an electrical connection example of the ink jet recording apparatus 10 shown in FIG. 1 and a host computer 40.
4 includes a control device 100, bubble detection sensors 201A to 201D and 202A to 202D, and an ink suction device 11. The ink suction device 11 includes, for example, a suction pump 19 that is a negative pressure generating means for applying a negative pressure to ink and suctioning the ink. The operation of the suction pump 19 is controlled by, for example, a step motor described later.
The ink jet recording apparatus 10 in FIG. 4 also includes a bubble intake valve 12A, a recording head 30, a carriage motor 2, and a paper transport mechanism 5.
The control device 100 is connected to the printer driver 41 of the host computer 40 via, for example, a local printer cable or a communication network. The printer driver 41 includes software that sends a command for causing the control device 100 to execute a printing, cleaning operation, or suction operation.

As shown in FIG. 4, the control apparatus 100 has an information file 43, and viscosity determination cleaning judgment information 45 and the like are stored in the information file.
The viscosity measurement cleaning judgment information 45 is the viscosity measurement cleaning performed to measure the viscosity of the ink of the ink cartridge 9A or the like when the recording head 30 and the tube 20A in FIG. This is information for determining whether normal cleaning is performed.

The viscosity measurement suction control information 46 is an ink suction device for measuring the viscosity of the ink in the tube 20A or the like when the control device 100 determines that the viscosity measurement cleaning is based on the viscosity measurement cleaning determination information 45. 11, the suction pump 19, the bubble intake valve 12 </ b> A, and the like, and information for controlling the bubble detection sensor 201 </ b> A and the like.
Based on the viscosity measurement suction control information 46, the control device 100 can measure the viscosity of ink in all the tubes 20A to 20D such as the tube 20A in FIG. It is also possible to measure only the viscosity of the ink in the tube 20A.

The viscosity determination information 47 is an example of velocity viscosity information indicating the relationship between the moving speed at which the bubbles introduced into the tube 20A and the like by the bubble intake valve 12A and the like move through the tube 20A and the viscosity of the ink, and the viscosity of the ink is determined. It is information to do.

FIG. 5A is a diagram illustrating an example of the viscosity determination information 47.
As shown in FIG. 5A, for example, the viscosity determination information 47 is data indicating the number of suction steps of the suction pump 19 of FIG. 4 on the horizontal axis and the viscosity on the vertical axis. The suction pump 19 is controlled by, for example, a step motor (not shown), and the number of suction steps on the horizontal axis indicates the number of steps of the step motor.
The number of suction steps is the number of steps of the step motor from when the first bubble detection sensor group 201 detects the bubble taken in by the bubble intake valve group 12 of FIG. 1 until the second bubble detection group 202 detects it. It is.

  That is, after the bubble H (see FIG. 2) passes through the first reference point (see FIG. 2) that is the position of the tube 20A or the like corresponding to the position of the first bubble detection sensor group 201, the second bubble detection sensor group. The time required to pass the second reference point (see FIG. 2), which is the position of the tube 20A or the like corresponding to the position 202, is measured by the number of steps of the step motor. That is, since the distance d between the first base point and the second reference point is determined, the bubble moving speed can be measured by the number of steps of the step motor.

  As described above, the control device 100 (see FIG. 4) includes the bubble intake valve 12a, which is an example of the above-described bubble intake means, and a bubble detection sensor, which is an example of a movement speed measurement unit that measures the movement speed of the bubbles. This is an example of a viscosity determination unit that controls (has) 201A and the like and determines the viscosity of ink based on viscosity determination information 47 that is an example of velocity viscosity information.

Further, the information file 43 in FIG. 4 stores viscosity negative pressure release time information 48.
The viscosity negative pressure release time information 48 is information indicating the negative pressure release time during normal cleaning corresponding to the viscosity of the ink.

FIG. 5B is a diagram illustrating an example of the viscosity negative pressure release time information 48.
As shown in FIG. 5B, the viscosity negative pressure release time information 48 includes, for example, the viscosity measured based on the above-described viscosity determination information 47 on the horizontal axis and the appropriate negative with respect to the viscosity during normal cleaning on the vertical axis. This is information indicating the pressure release time.
By setting the negative pressure release time according to the viscosity negative pressure release time information 48, it is possible to use an appropriate negative pressure release time according to the viscosity of the ink during normal cleaning.
As a result, it is possible to perform post-suction processing based on the optimal negative pressure release time for various types of ink with unknown viscosity as well as for ink whose viscosity has increased due to thickening or the like.
As shown in FIG. 5B, for example, the normal cleaning has three modes, and CL1 that sucks, for example, 0.2 gram (g) of ink according to the selection of the user of the recording apparatus 10 or the like.
CL2 that sucks 0.5 gram (g) of ink, and CL3 that sucks 0.8 gram (g) of ink.

  The control device 100 in FIG. 4 determines the viscosity of the ink based on the viscosity determination information 47, and determines the negative pressure release time in normal cleaning based on the viscosity and the viscosity negative pressure release time information 48. That is, the control device 100 having the viscosity negative pressure release time is also an example of a standby time determination unit that determines the standby time based on the viscosity of the ink (negative pressure release time).

Also, bubble discharge suction control information 49 is stored in the information file 43 of FIG.
The bubble discharge suction control information 49 is information for the recording apparatus 10 to execute a bubble discharge step of discharging the bubbles H (see FIG. 2) after the completion of the viscosity measurement cleaning.
As described above, if the bubbles H taken into the tube 20A or the like for measuring the viscosity of the ink are left in the tube 20A or the like as they are, there may be an obstacle to the ejection of ink from the recording head 30.
In this regard, if the recording apparatus 10 drives the ink suction apparatus 11 (see FIG. 4) based on the bubble discharge suction control information 49 and discharges the bubbles H, there is a problem that the ink discharge may be an obstacle. Can be prevented in advance.
Since the purpose of discharging and sucking bubbles is to discharge the bubbles H, the position of the bubbles H from the nozzle surface 61 (see FIG. 6) and the recording head 30 (see FIG. 1), for example, a second reference point ( Ink in the tube 20A and the like up to FIG.
Unlike the present embodiment, the bubble discharge and suction is performed by sucking and discharging all ink in the nozzle surface 61 (see FIG. 6), the recording head 30 (see FIG. 1), the tube 20A, and the like. May be.

Next, an example of the structure of the recording head 30 shown in FIG. 1 will be described with reference to FIGS.
6 and 7 show a structural example of the recording head 30 and a structural example of the ink suction device 11. FIG. 8 shows an example of the shape of the nozzle plate surface 61 of the recording head 30 viewed from the direction E in FIG. FIG. 9 shows an example of the internal structure including the piezoelectric vibrator of the recording head 30.
As shown in FIG. 6, the recording head 30 has a nozzle plate surface 61 on its lower surface. The nozzle plate surface 61 is an example of a nozzle surface. The nozzle plate surface 61 is the lower surface of the nozzle plate 62. The nozzle plate 62 has nozzle opening rows 54A to 54D as shown in FIG.

  FIG. 8 shows an arrangement example of the nozzle opening rows 54A to 54D. The nozzle opening rows 54A to 54D are formed in parallel with the U direction and have a predetermined interval in the T direction. The nozzle opening row 54A includes a plurality of nozzle openings 55A. Similarly, the nozzle opening rows 54B, 54C, and 54D are constituted by a plurality of nozzle openings 55B, 55C, and 55D, respectively.

The recording head 30 shown in FIG. 6 has an ink path 50 and a pressure chamber 51. The ink path 50 is connected to the nozzle openings 55A to 55D via the pressure chamber 51 as shown in FIG. Each ink path 50 is connected to the downstream end 20E of the tubes 20A to 20D, which are also shown in FIG.
Accordingly, the four types of ink are supplied to the ink path 50 through the tubes 20A to 20D shown in FIG. In FIG. 9, each ink supplied from the above-described tube is supplied to the pressure chamber 51 through the ink path 50.
At the time of printing, the piezoelectric vibrator 39 as a pressure generating element expands and contracts, thereby changing the volume of the pressure chamber 51 and causing pressure fluctuation in the ink in the pressure chamber 51. As a result, ink droplets can be ejected (also referred to as ejection) from the nozzle openings 55A to 55D.

Next, a structural example of the ink suction device 11 shown in FIG. 1 will be described with reference to FIGS.
6 and 7, the recording head 30 is positioned at the home position HP shown in FIG. Thus, when the recording head 30 is positioned at the home position HP, the nozzle plate surface 61 of the recording head 30 and the ink suction device 11 face each other. The ink suction device 11 is located below the nozzle plate surface 61. The ink suction device 11 includes a cap body 13, an absorbent material 22, and a suction pump 19.

  The cap body 13 is preferably made of a material that elastically deforms when it is in close contact with or pressure bonded to the nozzle plate surface 61 as shown in FIG. The cap body 13 is, for example, a box-shaped member having a bottom portion and four side surfaces, and an absorbent material 22 is accommodated in the cap body 13. The absorbent 22 is desirably made of a hydrophilic material such as foamed plastic. The discharge part 13A of the cap body 13 is connected to the suction pump 19 through the discharge tube 19A.

The elevating device 250 can raise the cap body 13 in the Z2 direction from the standby state shown in FIG. 6 to the suction state shown in FIG.
When the suction pump 19 is operated in the state of FIG. 7, the ink in the recording head 30 and the tube 20 </ b> A (see FIG. 1) is forced to the waste ink tank 120 side via the nozzle plate surface 61 and the absorber 22. Can be discharged.

Next, an embodiment of the cleaning method in the ink jet recording apparatus 10 of FIG. 1 which is a preferred embodiment of the liquid ejecting apparatus of the present invention will be described mainly with reference to FIGS. 10 and 11.
FIG. 10 is a diagram illustrating an example of a cleaning method of the ink jet recording apparatus 10.
FIG. 11 is a schematic view showing a main part of the ink jet recording apparatus 10.

When the inkjet recording apparatus 10 is activated and a cleaning instruction is given by a signal from the host computer 40 in FIG. 4, the control apparatus 100 in FIG. 2 performs the viscosity measurement based on the viscosity measurement clean judgment information 45. It is determined whether it is cleaning or other normal cleaning (step ST1).
If it is normal cleaning, the control unit 100 executes a normal cleaning sequence (step ST11).

If the cleaning is for viscosity measurement, the ink suction device 11 executes step ST2, which is an example of a viscosity determination suction step for sucking ink.
Specifically, the control device 100 in FIG. 4 controls the ink suction device 11 and the suction pump 19 based on the viscosity measurement suction control information 46 to measure the viscosity of the ink in the tube 20A and the like in FIG. Start suction.

Subsequently, the bubble intake valve 12A executes step ST3, which is an example of a bubble intake step for incorporating bubbles into the tube 20A or the like.
Specifically, as shown in FIG. 11A, the bubble intake valve 12A or the like is opened for 3 seconds, for example, and the bubbles H are taken into the tube 20A or the like.

Subsequently, the first bubble detection sensor group 201 and the second bubble detection sensor group 202 in FIG. 1 perform steps ST4 to ST7 which are an example of a movement speed measurement step in which the movement speed at which the bubbles H move through the tube 20A or the like is measured. Execute.
Specifically, the number of steps of the step motor 19a that controls the drive of the suction pump 19 during the period from when the bubble H passes the first reference point to the second reference point in FIG. To measure the moving speed of the bubbles H.
That is, it is determined by the first bubble detection sensor group 201 whether the bubble H has passed the first reference point corresponding to the position of the first bubble detection sensor 201A in FIG. 1 (step ST4). b)), the control unit 100 starts counting the number of steps of the step motor 19a (step ST5).
Subsequently, it is determined by the second bubble detection sensor group 202 whether or not the second reference point corresponding to the position of the second bubble detection sensor 201A has passed (step ST6), and when passed (see FIG. 11C). In step S7, the control device 100 finishes counting the number of steps of the step motor 19a and stops the viscosity measurement suction.

Subsequently, the control device 100 executes Step ST8 which is an example of a viscosity information acquisition step for acquiring the viscosity information of the liquid based on the velocity viscosity information indicating the relationship between the moving speed of the bubbles H and the viscosity of the ink.
Specifically, the control device 100 acquires ink viscosity information based on the number of steps of the step motor 19a counted in the above-described steps ST5 to ST7 and the viscosity determination information 47 of FIG. Based on the viscosity determination information 47 shown in FIG. 5A, for example, if the number of steps is 40,000, information indicating that the viscosity is 10 millipascal second (mPa · s) is acquired.

  Steps ST4 to ST8 described above are an example of a viscosity determination step in which the control device 100 determines the viscosity of the ink.

Subsequently, the control device 100 executes Step ST9 which is an example of a standby time determination step for determining a negative pressure release time (standby time) based on the viscosity information acquired in Step ST8 described above.
Specifically, the control device 100 sets a negative pressure release time in normal cleaning based on the viscosity of the ink based on the viscosity negative pressure release time information 48 of FIG. 4 (step ST9).
For example, as shown in FIG. 5B, in the case of normal cleaning CL1, if the ink viscosity is 10 millipascal second (mPa · s), the negative pressure release time is set to 8 seconds (s). .

Then, step ST10 which is an example of the bubble discharge | emission step which discharges the bubble H (refer FIG. 2) is performed.
Specifically, the control unit 100 in FIG. 2 sucks ink by an amount necessary for discharging the bubbles H from the nozzle openings 55A and the like in FIG. 6 based on the bubble discharge suction control information 49.
When the above-described bubble discharging step ends, the viscosity measurement cleaning ends.

  In the illustrated embodiment of the present invention, four ink cartridges that use inks such as black ink, cyan ink, magenta ink, and yellow ink can be mounted on the carriage. This ink cartridge is not limited to this, but includes only an ink cartridge for black ink, three ink cartridges for two or three color inks excluding black ink, or five or more inks. A cartridge may be provided.

  The present invention is not limited to the above embodiment as an ink jet recording apparatus, and various modifications can be made without departing from the scope of the claims. Furthermore, the above-described embodiments may be combined with each other. Further, the present invention is not limited to an ink jet recording apparatus, but a recording head used in an image recording apparatus such as a printer, a color material ejection head used in manufacturing a color filter such as a liquid crystal display, an organic EL display, and an FED (surface emitting). Electrode material ejecting heads used for electrode formation such as displays), liquid ejecting apparatuses using liquid ejecting heads for ejecting liquids such as bioorganic ejecting heads used for biochip manufacturing, sample ejecting apparatuses as precision pipettes, etc. Applicable.

1 is a diagram illustrating an ink jet recording apparatus that is a preferred embodiment of a liquid ejecting apparatus of the invention. FIG. Schematic showing the first bubble detection sensor, etc. Schematic showing the first bubble detection sensor, etc. FIG. 2 is a diagram illustrating an example of electrical connection of the recording apparatus in FIG. 1. The figure which shows an example of viscosity judgment information. The figure which shows the state just before an ink suction device attracts | sucks. The figure which shows the state which the ink suction device is sucking. FIG. 4 is a diagram illustrating a shape example of a nozzle plate surface of a recording head. FIG. 3 is a diagram illustrating an example of the internal structure of a recording head. The flowchart which shows the cleaning method in embodiment of this invention. Schematic which shows the principal part of a recording device.

Explanation of symbols

9A, 9B, 9C, 9D ... ink cartridge (an example of a liquid storage unit), 10 ... an ink jet recording device (an example of a liquid ejecting device), 11 ... an ink suction device (an example of a suction device), 12A, 12B, 12C, 12D ... Bubble intake valve, 20A, 20B, 20C, 20D ... Tube (an example of a liquid supply member), 30 ... Recording head (an example of a liquid ejecting head), 45 ...・ Viscosity measurement cleaning judgment information, 46... Viscosity measurement suction control information, 47... Viscosity judgment information, 48... Viscosity negative pressure release time information, 49. ..Control device, 201A, 201B, 201C, 201D, 202A, 202B, 202C, 202D ... Bubble detection sensor, H ... Bubble

Claims (10)

A liquid ejecting head having a nozzle surface for ejecting liquid;
A liquid storage section storing the liquid;
A liquid passage for supplying the liquid from the liquid reservoir to the liquid ejecting head;
A suction device that contacts the nozzle surface and sucks the liquid from the liquid jet head;
Viscosity determining means for determining the viscosity of the liquid;
A waiting time determining means for determining a waiting time from when the suction device stops sucking the liquid until the atmospheric pressure in the suction device becomes substantially equal to the atmospheric pressure, based on the viscosity of the liquid;
A liquid ejecting apparatus comprising: The viscosity determining means includes
A bubble intake means for taking bubbles into a liquid passage for supplying the liquid from the liquid reservoir to the liquid jet head;
A moving speed measuring means for measuring a moving speed at which the bubbles move in the liquid passage,
The liquid ejecting apparatus according to claim 1, wherein the viscosity of the liquid is determined based on speed viscosity information indicating a relationship between the moving speed and the viscosity of the liquid. The liquid suction means has a negative pressure generating means for applying a negative pressure to the liquid for suction.
The moving speed measuring means measures the moving speed according to the number of operations of the negative pressure generating means during a period from when the bubble passes the first reference point of the liquid passage to the second reference point. The liquid ejecting apparatus according to claim 2.   The liquid ejecting apparatus according to claim 3, wherein the moving speed measuring unit detects whether or not the bubble has passed through the first reference point and the second reference point by an optical sensor.   The standby time determination unit determines the standby time based on viscosity standby time information indicating a relationship between the viscosity and the standby time of the liquid suction unit. The liquid ejecting apparatus according to 1. A liquid ejecting apparatus for ejecting a liquid, a viscosity determining suction step for sucking the liquid;
A viscosity determining step in which the liquid ejecting apparatus determines the viscosity of the liquid;
A standby time determination step in which the liquid ejecting apparatus determines a standby time until the atmospheric pressure in the suction device becomes substantially equal to atmospheric pressure based on the viscosity; and
A cleaning method for a liquid ejecting apparatus, comprising: The viscosity determining step includes a bubble intake step in which bubbles are taken into a liquid passage through which the liquid ejecting apparatus supplies the liquid to the liquid ejecting head from a liquid storage unit storing the liquid;
A moving speed measuring step in which the liquid ejecting apparatus measures a moving speed at which the bubbles move in the liquid passage; and
A viscosity information acquiring step in which the liquid ejecting apparatus acquires viscosity information of the liquid based on speed viscosity information indicating a relationship between the moving speed and the viscosity of the liquid;
The method for cleaning a liquid ejecting apparatus according to claim 6, further comprising: The liquid suction means has a negative pressure generating means for applying a negative pressure to the liquid for suction.
In the moving speed measuring step, the moving speed is measured based on the number of operations of the negative pressure generating means during the period from the passage of the bubble through the first reference point of the liquid passage to the passage of the second reference point. The method for cleaning a liquid ejecting apparatus according to claim 7.   9. The cleaning method for a liquid ejecting apparatus according to claim 8, wherein in the moving speed measurement step, it is detected by an optical sensor whether or not the bubbles have passed through the first reference point and the second reference point. .   The method for cleaning a liquid ejecting apparatus according to claim 7, further comprising a bubble discharging step of discharging the bubbles after the standby time determining step.

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