JP4609535B2 - Liquid ejecting apparatus and liquid ejecting apparatus cleaning method - Google Patents

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 has been known. Such an ink jet recording apparatus records desired images such as characters and figures by ejecting minute ink droplets from the nozzles of the recording head onto the recording medium.
This ink jet recording apparatus has a relatively low noise during printing and can form small dots with a high density, and is used in many printing including color printing in recent years.

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.
As such an ink jet recording apparatus, there is a so-called off-carriage type apparatus that supplies ink from an ink cartridge storing ink to a recording head side through a tube. Some recording heads of this type of ink jet recording apparatus perform a cleaning process, which is a forced ink discharge process, in order to eliminate clogging of the recording head (for example, Patent Document 1).

JP 2000-289229 A (5th page, FIG. 2)

By the way, in Patent Document 1, a process called timer cleaning is performed when the power is turned on in accordance with a period in which the power is turned off and the ink jet recording apparatus is not used. This timer cleaning process can be performed with some consideration of the degree of ink drying when not in use, but no consideration is given to the growth of bubbles generated in the tube through which ink is fed.
As a result, due to the generation of bubbles and the growth of bubbles, the bubbles flow into the recording head from the tube, and ink droplets cannot be ejected from one or a plurality of nozzle openings of the recording head, resulting in poor printing. There is a problem.
The bubbles are generated by gas permeation or moisture permeation from the wall of the tube, and the amount and size of the bubbles are influenced by time and environmental temperature. Also, when the ink cartridge is replaced, air bubbles may flow into the tube.
Therefore, the present invention solves the above problems, detects bubbles in the liquid supply member that supplies the liquid, and forcibly discharges the bubbles from the liquid ejecting head, thereby preventing printing defects and using the liquid more effectively. An object of the present invention is to provide a liquid ejecting apparatus and a cleaning method for the liquid ejecting apparatus.

  The object is to provide a liquid ejecting head having a nozzle surface for ejecting liquid, a liquid storage part storing the liquid, a liquid supply member for supplying the liquid from the liquid storage part to the liquid ejecting head, and the liquid A bubble detection sensor that detects bubbles generated in the supply member, a closing portion that closes the liquid supply member in an openable / closable manner, and until the bubbles detected by the bubble detection sensor reach the liquid ejecting head. When the bubble detection sensor detects the bubble, and the control device that obtains the usable liquid volume that can be used, the liquid is ejected from the liquid ejection head to the usable liquid volume, and the ejection of the liquid is stopped. If the size of the bubble is later smaller than the preset size of the bubble, the liquid supply member is not closed and the nozzle is closed. A normal cleaning process in which the bubbles are sucked and discharged from the liquid ejecting head by contacting the surface of the liquid, and after the liquid is ejected from the liquid ejecting head to the usable liquid volume and the ejection of the liquid is stopped. When the size of the bubble is equal to or larger than the set size of the bubble, the liquid supply member is released by closing the liquid supply member in contact with the nozzle surface while the middle of the liquid supply member is closed by the closing portion. This is achieved by a liquid ejecting apparatus including a suction device that performs a powerful cleaning process for discharging the bubbles from the liquid ejecting head.

According to the configuration of the first invention, the liquid ejecting head has a nozzle surface that ejects the liquid. The liquid storage part stores the liquid.
The liquid supply member supplies liquid from the liquid storage unit to the liquid ejecting head. The bubble detection sensor detects bubbles generated in the liquid supply member. The control device obtains a usable liquid volume that can be used until the bubbles detected by the bubble detection sensor reach the liquid ejecting head.
When the bubble detection sensor detects a bubble, the suction device ejects the liquid from the liquid ejection head to the usable liquid volume and stops ejecting the liquid, and then performs a normal cleaning process or a powerful cleaning process to perform the liquid ejection. Bubbles are sucked by contacting the nozzle surface of the head and discharged from the liquid jet head.
That is, in the normal cleaning process, when the bubble detection sensor detects a bubble, the suction device has a bubble size larger after the liquid is ejected from the liquid ejection head to the usable liquid volume and the ejection of the liquid is stopped. If it is smaller than the preset size of the bubble, the middle of the liquid supply material is not closed. The bubbles are sucked and discharged from the liquid jet head.
In the powerful cleaning process, the liquid is ejected from the liquid ejection head to the usable liquid volume, and after the ejection of the liquid is stopped, the liquid is released by the closing portion when the bubble size is larger than the set size of the bubbles. The middle of the supply member is closed. In this closed state, the bubbles are sucked to release the closure of the liquid supply member, thereby discharging the bubbles from the liquid ejecting head. By closing the tube, a large negative pressure is generated in the tube, and even larger bubbles can be reliably discharged.

Thereby, when a bubble is generated in the liquid supply member, the bubble detection sensor can reliably detect the bubble. The control device obtains a usable liquid volume that can be used until the bubbles detected by the bubble detection sensor reach the liquid ejecting head.
After the liquid is ejected from the liquid ejecting head to the usable liquid volume and the liquid ejection is stopped, the suction device contacts the nozzle surface and changes the way of sucking the air bubbles according to the size of the air bubbles. Discharge from the liquid jet head. Accordingly, the bubbles in the liquid supply member can be reliably discharged to the outside through the liquid ejecting head. Therefore, it is possible to reliably prevent the droplets from being ejected when the liquid is ejected from the liquid ejecting head.
Further, since the control device obtains the usable liquid volume, the liquid corresponding to the usable liquid volume that is present until the bubbles reach the liquid ejecting head can be ejected from the liquid ejecting head. Therefore, the liquid that can be used before the bubbles are discharged can be effectively used so as not to be wasted and ejected from the liquid ejecting head. Therefore, when the liquid is ejected from the liquid ejecting head onto the medium, the number of sheets that can be ejected onto the medium can be increased.

According to a second aspect of the present invention, in the configuration of the first aspect, the usable liquid volume of the liquid is a length of the liquid supply member from the bubble detection sensor to the liquid ejecting head, and the liquid supply member. It is obtained from the cross-sectional area.
According to the configuration of the second invention, the usable liquid volume of the liquid can be obtained from the length of the liquid supply member from the bubble detection sensor to the liquid ejection head and the cross-sectional area of the liquid supply member.
Thus, the usable liquid volume can be reliably calculated in the control device, and the liquid for the usable liquid volume can be effectively ejected from the liquid ejecting head and used until just before the bubbles are discharged.

According to a third invention, in the configuration of the first invention or the second invention, the bubble detection sensor also detects the size of the bubble, and the suction device sets a suction time according to the size of the bubble. It is characterized by changing.
According to the configuration of the third invention, the bubble detection sensor detects the size of the bubble. The suction device changes the suction time according to the bubble size.
Thus, by changing the suction time according to the size of the bubble, for example, if the size of the bubble is large, the suction device can remove the bubble from the liquid ejecting head even if the bubble is a large size by increasing the suction time. Can be reliably discharged.

In a fourth aspect based on the second aspect, the plurality of bubble detection sensors are arranged at intervals with respect to the liquid supply member.
According to the configuration of the fourth invention, the plurality of bubble detection sensors are arranged at intervals with respect to the liquid supply member.
Thereby, the bubble detection sensor arranged at each position can give a signal for obtaining a usable usable liquid volume until each bubble reaches the liquid ejecting head to the control device. Thus, the usable liquid volume can be estimated in advance at each position of the liquid supply member.

According to a fifth aspect of the invention, in the configuration of the third aspect of the invention, the number of remaining liquid ejecting target media that can be ejected is calculated based on the usable liquid volume of the liquid and the ejection data given to the control device. Then, when the ejection of the liquid with respect to the number of the remaining liquid ejecting target media that can be ejected is finished, the ejection of the liquid is stopped, the bubbles are sucked by the suction device, and the liquid ejecting head It is characterized by discharging air bubbles.
According to the configuration of the fifth aspect of the invention, the number of remaining liquid ejection target media that can be ejected is calculated from the usable liquid volume of the liquid and the ejection data given to the control device, and the remaining ejectable remaining volume is calculated. When the liquid ejection is completed for the number of liquid ejection target media, the liquid ejection is stopped. The suction device sucks the bubbles and discharges the bubbles from the liquid ejecting head.
In this way, the number of remaining liquid ejecting target media that can be ejected is obtained in advance in the control device. The number of remaining liquid ejecting target media that can be ejected can be ensured until the bubbles are discharged from the liquid ejecting head, and can be effectively used without wasting consumption during ejection. You can increase the number.

  In the sixth aspect of the invention, the object is generated in the liquid supply member when the liquid is supplied from the liquid storage unit storing the liquid to the liquid ejecting head via the liquid supply member. A bubble detection step for detecting bubbles with a bubble detection sensor, and a usable liquid for obtaining a usable liquid volume of liquid that can be used before the bubbles detected by the bubble detection sensor reach the liquid ejecting head. A volume acquisition step, and when the bubble detection sensor detects the bubble, the liquid is ejected from the liquid ejecting head to the usable liquid volume and the ejection of the liquid is stopped. If the bubble is smaller than the preset size of the bubble, the bubble is brought into contact with the nozzle surface without closing the middle of the liquid supply member. A normal cleaning process of sucking and discharging from the liquid ejecting head, and the size of the bubbles after the liquid is ejected from the liquid ejecting head to the usable liquid volume and the ejection of the liquid is stopped. When the liquid supply member is larger than a set size of the liquid supply member, the liquid supply member is brought into contact with the nozzle surface while the middle of the liquid supply member is closed by the closing portion and sucked to release the liquid supply member to close the bubble. It is achieved by a cleaning method for a liquid ejecting apparatus, comprising: a powerful cleaning process for discharging from a head; and a bubble discharging step for performing a bubble discharging step.

According to the configuration of the sixth invention, the bubble detection step is generated in the liquid supply member when the liquid is supplied from the liquid storage unit storing the liquid to the liquid ejecting head via the liquid supply member. Bubbles are detected by a bubble detection sensor.
In the usable liquid volume acquisition step, the usable liquid volume of the liquid that can be used before the bubbles detected by the bubble detection sensor reach the liquid ejecting head is obtained by the control device.
In the bubble discharging step, when the bubble detection sensor detects a bubble, the liquid is ejected from the liquid ejecting head to the usable liquid volume, and the liquid ejection is stopped. After stopping the ejection, the suction device performs a normal cleaning process or a powerful cleaning process, contacts the nozzle surface, sucks the bubbles, and discharges the bubbles from the liquid ejecting head.
That is, in the normal cleaning process, when the bubble detection sensor detects a bubble, the suction device has a bubble size larger after the liquid is ejected from the liquid ejection head to the usable liquid volume and the ejection of the liquid is stopped. If it is smaller than the preset size of the bubble, the middle of the liquid supply material is not closed. The bubbles are sucked and discharged from the liquid jet head.
In the powerful cleaning process, the liquid is ejected from the liquid ejection head to the usable liquid volume, and after the ejection of the liquid is stopped, the liquid is released by the closing portion when the bubble size is larger than the set size of the bubbles. The middle of the supply member is closed. In this closed state, the bubbles are sucked to release the closure of the liquid supply member, thereby discharging the bubbles from the liquid ejecting head. By closing the tube, a large negative pressure is generated in the tube, and even larger bubbles can be reliably discharged.

Thereby, when a bubble is generated in the liquid supply member, the bubble detection sensor can reliably detect the bubble. The control device obtains a usable liquid volume that can be used until the bubbles detected by the bubble detection sensor reach the liquid ejecting head.
After the liquid is ejected from the liquid ejecting head to the usable liquid volume and the liquid ejection is stopped, the suction device contacts the nozzle surface and changes the way of sucking the air bubbles according to the size of the air bubbles. Drain from the liquid jet head. Accordingly, the bubbles in the liquid supply member can be reliably discharged to the outside through the liquid ejecting head. Accordingly, when the liquid is ejected from the liquid ejecting head, it is possible to reliably prevent the liquid droplet from being ejected.
Further, since the control device obtains the usable liquid volume, the liquid corresponding to the usable liquid volume that is present until the bubbles reach the liquid ejecting head can be ejected from the liquid ejecting head. Therefore, the liquid that can be used before the bubbles are discharged can be effectively used so as not to be wasted and ejected from the liquid ejecting head. Therefore, when the liquid is ejected from the liquid ejecting head onto the medium, the number of sheets that can be ejected onto the medium can be increased.

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 jet head, 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, 9D are an example of a liquid storage unit. 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 20A, 20B, 20C, and 20D are examples of a liquid supply member. 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, for example, 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 detection sensor shown in FIG. 1 will be described.
The tubes 20A to 20D include, for example, a first bubble detection sensor group 200, a second bubble detection sensor group 201, and a third bubble detection sensor group 202.
The first bubble detection sensor group 200 is located closest to the recording head 30. The third bubble detection sensor group 202 is at a position close to the upstream end side of the tube. The second bubble detection sensor group 201 is located between the first bubble detection sensor group 200 and the third bubble detection sensor group 202.

  The first bubble detection sensor group 200 to the third bubble detection sensor group 202 are, for example, a group of a plurality of optical sensors for detecting whether or not bubbles are present in the tubes 20A to 20D. The first bubble detection sensor group 200 to the third bubble detection sensor group 202 are preferably arranged as close to the recording head 30 as possible. As described above, the tube is a member that supplies ink that is a liquid. However, since the tube preferably uses the optical first bubble detection sensor group 200 to the third bubble detection sensor group 202, it is translucent or ink. It is desirable to be made of a material having a transparency that allows optical detection of bubbles inside.

Bubbles are generated in each tube by gas permeation or moisture permeation from the tube depending on the environmental temperature and usage time. Also, when the ink cartridges 9A to 9D are replaced in the cartridge holder 8, bubbles may be generated.
Therefore, the first bubble detection sensor group 200 to the third bubble detection sensor group 202 are used to detect bubbles that are supposed to be generated in the tubes 20A to 20D at a plurality of locations of the tubes. The first bubble detection sensor group 200 includes bubble detection sensors 200A to 200D. The second bubble detection sensor group 201 includes bubble detection sensors 201A to 201D. The third bubble detection sensor group 202 includes bubble detection sensors 202A to 202D.
A choke valve 600 is provided in the middle of each tube 20A to 20D. The choke valve 600 is an example of a closing portion that can close the middle of each tube. In this example, each choke valve is located between the first bubble detection sensor group 200 and the second bubble detection sensor group 201.

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 the ink suction device 11 is an example of a suction device. 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. Further, the ink suction device 11 can perform a cleaning operation of 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.
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. 2 shows an electrical connection example of the ink jet recording apparatus 10 shown in FIG.
2 includes a control device 100, bubble detection sensors 200A to 200D, 201A to 201D and 202A to 202D, an ink suction device 11, ink cartridges 9A, 9B, 9C and 9D, tubes 20A to 20D, and a choke. The valve 600, the recording head 30, the carriage motor 2, and the paper transport mechanism 5 are provided.
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.

Next, a structural example of the recording head 30 shown in FIG. 1 will be described with reference to FIGS.
3 and 4 show a structural example of the recording head 30 and a structural example of the ink suction device 11. FIG. 5 shows an example of the shape of the nozzle plate surface 61 of the recording head 30 as viewed from the direction E in FIG. FIG. 6 shows an example of the internal structure including the piezoelectric vibrator of the recording head 30.
As shown in FIG. 3, 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. 5 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. 3 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. 6, 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.
3 and 4, 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. 3 to the suction state shown in FIG.
When the suction pump 19 is operated in the state of FIG. 4, bubbles in the tube described later can be discharged from the nozzle openings 55 of the nozzle plate surface 61 to the waste ink tank 120 side through the discharge tube 19A. The operation of the suction pump 19 is performed according to a command from the control device 100.
Further, by operating the suction pump 19, clogging of the ink in the nozzle opening of the nozzle plate surface 61 can be forcibly discharged to the waste ink tank 120 side through the absorbent material 22.
Further, as shown in FIG. 4, in a state where the cap body 13 is in close contact with or pressure-bonded to the nozzle plate surface 61, moisture retention of the nozzle opening of the nozzle plate surface 61 and moisture retention of the absorbent material 22 can be performed.

Next, the tubes 20A to 20D, the first bubble detection sensor group 200 to the third bubble detection sensor group 202, and the ink cartridges 9A to 9D shown in FIG. 1 will be described with reference to FIGS.
As shown in FIG. 7, for example, ink packs 9R are accommodated in the ink cartridges 9A to 9D, respectively. This ink pack 9R is made of a flexible material, and each ink pack 9R contains different types of ink. As described above with respect to the ink pack 9R, the ink pack 9R is pushed by sending pressurized air from the pressure pump 21 shown in FIG. As a result, the pressurized ink pack 9R can be sent out to the tubes 20A to 20D.

  The bubble detection sensors 200A to 200D of the first bubble detection sensor group 200 are disposed at the same distance from the recording head 30 corresponding to the tubes 20A to 20D, respectively. Similarly, the bubble detection sensors 201A to 201D of the second bubble detection sensor group 201 are disposed at the same distance from the recording head 30 with respect to the tubes 20A to 20D. Further, the bubble detection sensors 202A to 202D of the third bubble detection sensor group 202 are arranged at the same distance from the recording head 30, respectively.

  FIG. 9 shows the arrangement of each sensor and the tube length, and the bubble detection sensors 200A to 200D are separated from the recording head 30 by the tube length TX1. The bubble detection sensors 201A to 201D are separated from the recording head 30 by the tube length TX2. The bubble detection sensors 202A to 202D are separated by the tube length TX3.

FIG. 10 shows a cross-section of a part of the tubes 20A to 20D and a structural example of the bubbles H generated therein and the bubble detection sensors 200A to 200D, 201A to 201D, 202A to 202D.
The tubes 20A to 20D have the same diameter along the length direction and are preferably circular in cross section. The bubbles H are air bubbles generated in the ink 1000. The diameter of the bubble H is indicated by t as the bubble size.

The bubble detection sensors 200A to 200D, 201A to 201D, and 202A to 202D are the same, and are, 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.
The light 400 </ b> L emitted from the light emitting unit 400 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 is given to the control unit 100. The waveform width W of the detection waveform 402 corresponds to the bubble size t, and the control device 100 can obtain the bubble size t based on the detection waveform 402.

As shown in FIG. 9, three sets of bubble detection sensor groups 200, 201, and 202 are arranged in each of the tubes 20A to 20D. By arranging a plurality of bubble detection sensor groups in this way, the volume of the liquid corresponding to each of the tube lengths TX1, TX2 and TX3 can be calculated at the position of each bubble detection sensor group.
Each bubble detection sensor is electrically connected to the control device 100 as shown in FIGS. The bubble detection sensors 200A to 200D of the first bubble detection sensor group 200 of FIG. 9 can detect the presence or absence of bubbles at the position P1 in the respective tubes 20A to 20D.
Each of the bubble detection sensors 201A to 201D of the second bubble detection sensor group 201 can detect the presence or absence of bubbles at the position P2 in the tubes 20A to 20D, respectively. Similarly, each of the bubble detection sensors 202A to 202D of the third bubble detection sensor group 202 can detect the presence / absence of bubbles at the position P3 in the tubes 20A to 20D, respectively.

  Moreover, the control device 100 shown in FIG. 10 can acquire the following usable ink volume (an example of a usable liquid volume). That is, the remaining usable ink volume that can be used until the bubbles detected by each bubble detection sensor reach the recording head 30 (an example of a liquid ejecting head) from the magnetic sensor can be obtained. This usable ink volume can also be called a usable ink amount or a printable ink amount. The usable ink volume can be calculated as follows at each of the positions P1, P2, and P3 shown in FIG.

  FIG. 11 shows a calculation example of the usable ink volume. The usable ink volume refers to the volume of ink (liquid) that can be used until the bubbles detected by the bubble detection sensor reach the recording head. The usable ink volume can be obtained by the calculation procedure as shown in FIG. 11, and the table of the calculation example as shown in FIG. 11 is obtained from the printer driver 41 with respect to the control device 100 shown in FIG. It is sent as an information file 43.

  In FIG. 11, when the bubble detection sensors 200A to 200D detect bubbles in the tubes 20A to 20D at the position P1 shown in FIG. 9, the usable ink volume is obtained by the tube length TX1 × the tube cross-sectional area S. It is done. Similarly, when the bubble detection sensors 201A to 201D detect bubbles in the tubes 20A to 20D at the position P2, the usable ink volume is obtained by tube length TX2 × tube cross-sectional area S. Similarly, in the position P3, when the bubble detection sensors 202A to 202D detect bubbles in the tubes 20A to 20D, the usable ink volume is obtained by the tube length TX3 × the tube cross-sectional area S. The cross-sectional area of this tube is a cross-sectional area obtained from the inner diameter of the tube.

Next, a structural example of the choke valve 600 will be described with reference to FIG.
The choke valve 600 is for closing the middle of the flow path of the tubes 20A to 20D so that it can be opened and closed. The choke valve 600 includes an actuator 601 such as an electromagnetic solenoid and an operation member 602.
When the actuator 601 is actuated by a command from the control device 100, the moving body 602A of the operation member 602 moves to the fixed body 602B side, so that the moving body 602A and the fixed body 602B are in the middle of the flow paths of the tubes 20A to 20D. Can be closed. With the tube flow path closed in this way, the ink suction device 11 sucks the nozzle plate surface 61 as shown in FIGS. 4 and 8, so that the recording head and choke are compared with the case where the tube is not closed. A greater negative pressure can be applied in the tube between the valves 600.

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 with reference to FIGS. This cleaning method is also called a bubble discharging method.
FIG. 14 shows an example of the relationship between the bubble size t shown in FIG. 10, the suction time during cleaning, and the type of cleaning.
This suction time is a time for the ink suction device 11 to suck the nozzle plate surface 61 as shown in FIGS. There are two types of cleaning, normal cleaning processing and strong cleaning processing (also called choke cleaning).

  In the normal cleaning process, the choke valve 600 shown in FIG. 12A does not operate and the tubes 20A to 20D are opened, and the ink suction device 11 sucks the nozzle plate surface 61 to discharge the bubbles from the recording head. Say what to do. The intense cleaning process is a process in which a negative pressure larger than that in the normal cleaning process is applied to the recording head and the tube, and then the negative pressure is released. In other words, in the powerful cleaning process, the ink suction device 11 sucks the nozzle plate surface 61 with the choke valve 60 shown in FIG. Air bubbles are discharged from the nozzle opening of the recording head.

In the state 1 of FIG. 14, when no bubbles are detected, the choke valve remains open and the ink suction device 11 is separated from the nozzle plate surface 61 as shown in FIG. 3 and does not perform suction.
On the other hand, the normal cleaning process in the state 2 and the state 3 is as follows, for example. When the bubble size t is 0.5 mm or less, the choke valve remains open as shown in FIG. 12A, and the ink suction device 11 sucks the nozzle plate surface 61 for 5 seconds as shown in FIGS. The air bubbles are discharged from the nozzle opening of the recording head. When the bubble size t is 1 mm or more and less than 3 mm, the ink suction device 11 sucks the nozzle plate surface 61 for 10 seconds while the choke valve is open, and the bubbles are discharged from the nozzle opening of the recording head.

The powerful cleaning process in the state 4 and the state 5 is, for example, as follows. When the bubble size t in the state 4 is 3 mm or more which is a predetermined set size and is 3 mm or more and less than 5 mm, the choke valve 600 closes the tube as shown in FIG. As shown in FIGS. 4 and 8, the ink suction device 11 suctions from the nozzle plate surface 61 for 15 seconds to increase the negative pressure in the tube, and then opens the choke valve 600 to discharge the bubbles from the recording head. If the bubble size t in state 5 is 5 mm or more, the choke valve closes the tube. The ink suction device 11 sucks from the nozzle plate surface 61 for 20 seconds to increase the negative pressure in the tube, and then opens the choke valve 600 to discharge the bubbles from the recording head.
In this way, the type of cleaning process is changed according to the bubble size, and the suction time of the ink suction device is also changed. When the bubble size is larger than the set size, the normal cleaning process is switched to the powerful cleaning process. Further, as the bubble size increases, the suction time becomes longer in both the normal cleaning process and the powerful cleaning process.
FIG. 13 shows an example of a cleaning method for the ink jet recording apparatus 10.
Printing start step ST1
In step ST1, the control device 100 shown in FIG. 2 gives drive signals to the paper transport mechanism 5, carriage motor 2 and recording head 30, and gives commands to the pressure pumps of the ink cartridges 9A to 9D. Normal printing (printing) is started.
Simultaneously with the start of printing, whether or not bubbles are generated in the tubes 20A, 20B, 20C, and 20D shown in FIG. 1 is shown in FIG. 9 using the bubble sensors 200A to 200D, 201A to 201D, and 202A to 202D. The monitoring operation is started at the indicated positions P1, P2 and P3.

Bubble detection step ST2
In step ST2 of FIG. 13, when any bubble detection sensor detects the bubble H as shown in FIG. 10, the bubble size t of the bubble H is also detected at that time. For example, the case where the bubble detection sensor 202A shown in FIG. 9 detects the bubble H as shown in FIG. 10 in the tube 20A at the position P3 will be described. When the bubble H is detected, the process proceeds to step ST3.

Usable liquid volume acquisition step ST3
In step ST3 shown in FIG. 13, the control device 100 shown in FIG. 10 calculates the usable ink volume V1 that can be printed using the table of the calculation example of the usable ink volume shown in FIG. In FIG. 11, when air bubbles are detected at the position P1, the usable ink volume V1 is obtained by the tube length TX3 × the tube cross-sectional area S.

Required liquid volume acquisition step ST4
In step ST4 of FIG. 13, predetermined print image data is sent from the printer driver 41 shown in FIG. The control device 100 calculates a necessary ink volume V2 necessary for future printing from the usable ink volume (usable liquid volume) V1 shown in FIG. 11 and the given print image data (an example of ejection data). .

Remaining number of media acquisition step ST5
In step ST5 shown in FIG. 13, the control device 100 calculates the number of remaining printable sheets (number of liquid ejection target media) from the printable ink volume V1 and the necessary ink volume V2.
Injection stop step ST6
In step ST6 shown in FIG. 13, after printing up to the number of printable sheets (an example of the number of remaining liquid ejectable media that can be ejected), the control apparatus 100 instructs each element to print. Cancel.
In the bubble detection step ST2 of FIG. 13, as an example, since the bubble detection sensor 202A has already detected the bubble H shown in FIG. 10 at the position P3 in the tube 20A, the process proceeds to the bubble discharge step ST7 of FIG.

Bubble discharge step ST7
In step ST7 shown in FIG. 13, the ink suction device 11 in the standby state shown in FIGS. 3 and 7 is raised in the Z2 direction to the position of the suction state shown in FIGS. As a result, the cap body 13 is brought into close contact or pressure contact with the nozzle plate surface 61. In the position P3 of FIG. 9, the bubble detection sensor 202A has detected the bubbles in the tube 20A, but these bubbles have already reached the position just before the recording head 30.
In this case, as illustrated in FIG. 14, when the bubble size t is less than the set size of 3 mm, the above-described normal cleaning process is performed. When the bubble size t is 3 mm or more of the set size, the above-described powerful cleaning process is performed.
From this, by operating the suction pump 19 shown in FIGS. 4 and 8, for example, the bubbles reaching the downstream end 20E of the tube 20A shown in FIG. 4 can be transferred to the nozzle plate surface through the ink path 50 and the nozzle openings 55A. 61 can be forcibly discharged to the waste ink tank 120 side through the absorbent 22. In this way, when the ink suction device 11 forcibly performs the cleaning process on the recording head 30, the air bubbles that have reached just before the recording head 30 can be reliably discharged from the recording head to the outside. it can. Therefore, it is possible to avoid printing defects such as so-called ink loss due to air bubbles being discharged from the nozzle opening row during printing at the nozzle openings of the recording head 30.

Also, after the bubble present at position P3 in FIG. 9 is detected by bubble detection sensor 202A, the usable ink volume at position P3 shown in FIG. 11 is calculated and printed after the remaining number of printable sheets is printed. To stop. Therefore, it is possible to print by ejecting from the recording head 30 so as to use up all of the usable ink volume at the position P3.
Thus, waste of ink consumption can be prevented and the number of printable recording media can be increased. In this way, the ink volume in the tube that can be used before the bubbles generated in the tube flow into the recording head is estimated by calculation. Until the bubbles reach immediately before the recording head, printing can be performed on the paper using the ink of the usable ink volume. When the bubbles reach immediately before the recording head, the bubbles are forcibly discharged to the outside from the nozzle openings of the recording head by using the ink suction device 11 as shown in FIGS. Thus, the printing operation is performed until the bubbles reach the recording head, and then the bubbles can be reliably cleaned and discharged. The bubbles are forcibly discharged immediately before the bubbles affect the printing or the recovery operation of the recording head, that is, immediately before the bubbles do not flow into the recording head. For this reason, it is desirable to dispose the bubble detection sensor as close to the recording head as possible.

  Such bubble detection and usable ink volume calculation are the same in the other bubble detection sensors 200B to 200D, 201A to 201D, and 202A to 202D shown in FIG. In the example of FIG. 9, a first bubble detection sensor group 200, a second bubble detection sensor group 201, and a third bubble detection sensor group 202 are arranged at positions P1, P2, and P3, respectively. However, the present invention is not limited to this, and at least one bubble detection sensor group may be provided. Further, there may be four or more bubble detection sensor groups. Depending on the number of the bubble detection sensor groups, it is possible to more surely grasp at which position of the tubes 20A to 20D the bubble is generated.

  In FIG. 13, if the bubble detection sensor does not detect a bubble, the process proceeds to step ST8 to determine whether or not to continue printing. Also in step ST7, it is determined in step ST8 whether to continue printing. When printing is continued, the process returns to step ST1.

FIG. 15 shows another embodiment of the present invention. The embodiment of FIG. 15 is basically the same as the embodiment of FIG. 4, and therefore, the same portions are denoted by the same reference numerals and the description thereof is used.
The embodiment of FIG. 15 is different from the embodiment of FIG. 4 in that a partition wall 225 is provided in the cap body 13 of the ink suction device 11. The partition 225 is a partition for dividing the absorbent 22 into nozzle opening rows 54A to 54D, respectively. For this purpose, the partition wall 225 is formed between the nozzle opening rows 54A to 54D. The cap body 13 is connected to the suction pump 19 by separate discharge tubes 19A, 19B, 19C, and 19D. A valve 19G is provided in the middle of the discharge tubes 19A to 19D. This valve 19G can be opened and closed by a command from the control device 100.
Therefore, for example, when air bubbles are generated in the tube 20A, the control device 100 opens only the valve 19G of the discharge tube 19A and closes the other three valves 19G. As a result, when the suction pump 19 is activated, the bubbles in the tube 20A can be forcibly discharged to the waste ink tank 120 through the ink path 50 and the absorber 22 and the discharge tube 19A and the valve 19G. Such a thing can be similarly performed even when bubbles are generated in the other tubes 20B to 20D.

In the embodiment of the present invention, bubbles generated in a tube as a liquid supply member are monitored by a bubble detection sensor. If the bubbles grow, they are forcibly discharged out of the recording head using an ink suction device. In this case, before the bubbles flow into the recording head during the printing operation, the printing operation is stopped and the bubbles are forcibly discharged from the recording head. Thus, it is possible to prevent the occurrence of printing defects such as ink drop omission during printing.
The timing at which the bubble detection sensor detects bubbles is preferably during printing. However, the bubble detection sensor can be performed even when the power is turned on or before printing is started.

In the embodiment of the present invention, the bubble detection sensor uses an optical sensor arranged outside the tube, and when the bubble passes, the bubble detection sensor sends a detection waveform signal to the control device, and at that time, the detection waveform signal The bubble size is detected by the waveform width. However, the present invention is not limited to this, and the bubble detection sensor may be provided in the middle of the flow path of the tube.
The closing portion is not limited to the example shown in FIG. 12, and the arrangement position of the closing portion in the tube may be changed, and the structure of the closing portion may be of other types. For example, the operation member 600 of FIG. 12 may use two moving bodies 602A and 602B to move in a direction in which both moving bodies 602A and 602B approach each other and close the tube.

  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 ejection heads used for electrode formation such as displays), liquid ejection devices using liquid ejection heads that eject liquids such as bio-organic matter ejection heads used in biochip manufacturing, sample ejection devices 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. FIG. 2 is a diagram illustrating an example of electrical connection of the recording apparatus in FIG. 1. FIG. 3 is a diagram illustrating a structure example of a recording head and an ink suction device. 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 figure which shows the bubble detection sensor group arrange | positioned with respect to a tube, and the ink suction device shows a standby state. The figure which shows the example of arrangement | positioning of a bubble detection sensor group, and the state which the ink suction device is sucking the bubble. The figure which shows the bubble detection sensor group arrange | positioned with respect to the tube and a tube. The figure which shows the structural example of a tube, the bubble in a tube, and a bubble detection sensor. The table which shows the example of calculation of the usable ink volume (usable liquid volume) in embodiment of this invention. The figure which shows the structural example of the closing part in embodiment of this invention. The flowchart which shows the cleaning method in embodiment of this invention. The figure which shows the example of relationship between bubble size, the suction time at the time of cleaning, and the kind of cleaning. The figure which shows another embodiment of this invention.

Explanation of symbols

  9A, 9B, 9C, 9D ... ink cartridge (an example of a liquid storage unit), 10 ... an ink jet recording apparatus (an example of a liquid ejecting apparatus), 11 ... an ink suction apparatus (an example of a suction apparatus), 20A, 20B, 20C, 20D ... Tube (an example of a liquid supply member), 30 ... Recording head (an example of a liquid ejecting head), 100 ... Control device, 200A, 200B, 200C, 200D, 201A, 201B, 201C, 201D, 202A, 202B, 202C, 202D ... Bubble detection sensor, 600 ... (Choke valve) closing part, H ... Bubble.

Claims (5)

A nozzle surface with a nozzle opening for ejecting liquid;
A liquid supply member for supplying the liquid to the nozzle opening;
A bubble detection sensor for detecting bubbles in the liquid supply member;
A closing portion for closing the middle of the liquid supply member so as to be openable and closable;
When the bubble detection sensor detects the bubble, if the size of the bubble is smaller than a preset size of the bubble, the nozzle is not closed in the middle of the liquid supply member. A normal cleaning process in which the bubbles are sucked in contact with the surface and discharged from the liquid ejecting head; and when the size of the bubbles is equal to or larger than the set size of the bubbles, the closing portion A suction device that performs a powerful cleaning process of discharging the bubbles from the liquid ejecting head by releasing the closed state of the liquid supply member by contacting and suctioning the nozzle surface in a closed state A liquid ejecting apparatus.   The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus determines the size of the bubbles based on a time during which the bubble detection sensor continues to detect the bubbles.   The liquid ejecting apparatus according to claim 1, wherein the suction device changes a suction time according to a size of the bubble.   4. The liquid ejecting apparatus according to claim 1, wherein a plurality of the bubble detection sensors are arranged at intervals with respect to the liquid supply member. A bubble detection step of detecting bubbles in the liquid supply member by a bubble detection sensor when supplying the liquid via a liquid supply member to a nozzle opening for ejecting a liquid provided on a nozzle surface;
When the bubble detection sensor detects the bubble, if the size of the bubble is smaller than the preset size of the bubble, the closing portion provided in the middle of the liquid supply member is closed. Without a normal cleaning process in which the bubbles are sucked and discharged from the liquid ejecting head, and when the size of the bubbles is equal to or larger than the set size of the bubbles, the closing portion is provided in the middle of the liquid supply member. A liquid ejection step for performing a powerful cleaning process for discharging the bubbles from the liquid ejection head by releasing the closure of the liquid supply member by sucking in a closed state. How to clean the device.

Images