JP5463942B2 - Fluid ejecting apparatus and cleaning method - Google Patents

Description

  The present invention relates to a fluid ejecting apparatus and a cleaning method for the fluid ejecting apparatus.

  2. Description of the Related Art Conventionally, ink jet printers are widely known as fluid ejecting apparatuses that eject a fluid onto a medium. In this printer, a printing process is performed on a medium by ejecting ink (fluid) from a nozzle opening formed in a fluid ejecting head.

  In such a printer, dot omission may occur due to bubbles mixed in the fluid ejecting head or nozzles being clogged. For this reason, conventionally, there has been a printer that performs cleaning in which ink in a fluid ejecting head is pressurized and discharged from a nozzle opening (for example, Patent Document 1).

JP 2007-152725 A

  In such cleaning, a large amount of ink is wasted, and in Patent Document 1, the amount of pressure applied to the ink is changed according to the degree of printing failure. However, since a considerable amount of ink is still wasted with cleaning, further reduction of ink consumption has been a problem.

  SUMMARY An advantage of some aspects of the invention is that it provides a fluid ejecting apparatus that can clean a fluid ejecting head while suppressing consumption of fluid.

In order to achieve the above object, a fluid ejecting apparatus of the present invention supplies a fluid ejecting head provided with a plurality of nozzle openings for ejecting fluid, and supplying the fluid from the fluid supply source side toward the fluid ejecting head side. As a method for cleaning the fluid supply path and the fluid ejecting head, the fluid in the fluid ejecting head swells from the nozzle opening without supplying the fluid from the fluid supply source side via the fluid supply path. Any of the non-fluid supply cleaning to be performed and the fluid supply cleaning to be discharged from the nozzle opening while supplying the fluid from the fluid supply source side through the fluid supply path is an operation before the cleaning is performed. And selection means for selecting based on .

According to this configuration, when the selection unit selects the non-fluid supply cleaning, the fluid ejection head can be cleaned while suppressing the consumption of the fluid. That is, by selectively performing the non-fluid cleaning instead of the fluid supply cleaning that consumes the fluid, the fluid ejection head can be cleaned while suppressing the consumption of the fluid. Since the selection unit selects the cleaning method based on the operation before the cleaning is performed, either the fluid non-supply cleaning or the fluid supply cleaning can be selectively executed according to the situation.

  The fluid ejecting apparatus of the present invention further includes a nozzle inspecting device that inspects the presence or absence of a defective nozzle that does not eject a necessary amount of fluid, and the selection unit includes a plurality of the defective nozzles adjacent to each other based on the result of the inspection. If they are present, the fluid supply cleaning is selected, while if the plurality of defective nozzles are not adjacent to each other, the fluid non-supply cleaning is selected.

  According to this configuration, when a plurality of defective nozzles that do not eject a necessary amount of fluid are adjacent to each other, fluid supply cleaning is performed, so that relatively severe clogging is eliminated while supplying fluid. Or large bubbles over a plurality of nozzles can be discharged. On the other hand, even if there are a plurality of defective nozzles, if they are not adjacent to each other, the fluid non-supply cleaning is executed. Therefore, by causing the fluid to bulge from the nozzle opening, the fluid bulges out. Bubbles mixed in the portion can be pushed out to the atmosphere side outside the nozzle opening. That is, by selectively performing the fluid non-supply cleaning, small bubbles in the nozzle can be discharged while suppressing the consumption of the fluid.

  In the fluid ejecting apparatus according to the aspect of the invention, the nozzle inspection device performs the inspection when the power is turned on, and the selection unit performs the fluid supply cleaning when the defective nozzle is detected in the inspection when the power is turned on. Select.

  According to this configuration, when there is a defective nozzle when the power is turned on, it is highly likely that the fluid staying in the nozzle has deteriorated. If the fluid supply cleaning is executed, the deteriorated fluid in the nozzle can be discharged.

  In the fluid ejecting apparatus according to the aspect of the invention, the fluid supply source may be a fluid container that is detachably attached to an upstream end of the fluid supply path, and the selection unit may perform an operation immediately before the fluid ejecting apparatus. If the body is attached or detached, the fluid supply cleaning is selected.

  According to this configuration, since the fluid supply cleaning is executed when the operation immediately before the fluid ejecting apparatus is the attachment / detachment of the fluid container, the large bubbles mixed in the fluid supply path as the fluid container is attached / detached. Can be discharged together with the ink.

In the fluid ejecting apparatus according to the aspect of the invention, the selection unit selects the fluid non-supply cleaning when the operation immediately before the fluid ejecting apparatus is the fluid supply cleaning.
According to this configuration, since the fluid non-supply cleaning is performed after the fluid supply cleaning is performed, the meniscus in the nozzle disturbed by the ink discharge can be adjusted.

  In the fluid ejecting apparatus according to the aspect of the invention, the fluid ejecting apparatus further includes a wiping mechanism that performs wiping of a nozzle forming surface in which the nozzle opening is formed in the fluid ejecting head, and the selection unit performs an operation immediately before the fluid ejecting apparatus. In the case of the wiping according to the above, the fluid non-supply cleaning is selected.

  According to this configuration, since the fluid non-supply cleaning is executed after the wiping is performed, the meniscus in the nozzle disturbed by the wiping can be adjusted, or the air bubbles pushed into the nozzle can be discharged.

To achieve the above object, according to the cleaning method of the present invention, as a method of cleaning a fluid ejecting head provided with a plurality of nozzle openings for ejecting fluid, fluid supply from the fluid supply source side toward the fluid ejecting head side is performed. Fluid non-supply cleaning that causes the fluid in the fluid ejecting head to bulge from the nozzle opening without supplying the fluid via a path, and the fluid from the fluid supply source side via the fluid supply path A selection step of selecting one of the fluid supply cleanings for discharging the fluid in the fluid ejecting head from the nozzle openings while supplying the fluid based on the operation before the cleaning is performed .

  According to this configuration, the fluid ejection head can be cleaned while suppressing the consumption of the fluid by selectively executing the fluid non-supply cleaning instead of the fluid supply cleaning that consumes the fluid.

1 is a schematic front view illustrating a schematic configuration of an ink jet printer according to a first embodiment. The bottom view which shows the structure of a line head. FIG. 3 is a cross-sectional view illustrating a schematic configuration in a fluid ejecting head. Sectional drawing which shows schematic structure of a capping apparatus. Sectional drawing which shows schematic structure of a wiping apparatus. It is sectional drawing for demonstrating the structure and effect | action of a pressure provision mechanism in 1st Embodiment, (a) is before pressurization, (b) shows the time of pressurization. It is sectional drawing for demonstrating ink non-supply cleaning, (a) before pressurization, (b) at the time of pressurization, (c) at the time of pressure reduction, (d) shows after stationary. The graph which shows the relationship between pressurization time and pressure reduction time. The table | surface which shows the flow-path conditions of the ink jet type printer in 1st Embodiment. (A) is a table | surface which shows the range of pressurization ink amount, (b) is a table | surface which shows the range of pressurization time and pressure reduction time. The schematic diagram explaining the structure of a nozzle test | inspection apparatus and a control apparatus. A table showing a relationship between a phenomenon to be dealt with and a cleaning method. 6 is a flowchart illustrating a cleaning method selection process according to the first embodiment. The model front view which shows schematic structure of the ink jet type printer in 2nd Embodiment. Sectional drawing which shows the structure of the pressure provision mechanism in 2nd Embodiment. It is sectional drawing for demonstrating the structure and effect | action of a differential pressure | voltage valve, (a) at the time of valve closing, (b) shows the time of valve opening. 9 is a flowchart showing a cleaning method selection process associated with a nozzle inspection execution command in the second embodiment. 12 is a flowchart illustrating a selection method of a leaning method according to a cleaning execution command in the second embodiment.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is embodied in an ink jet printer (hereinafter simply referred to as a “printer”) which is a kind of fluid ejecting apparatus will be described with reference to FIGS. 1 to 13. In the following description, when referring to “front-rear direction”, “left-right direction”, and “up-down direction”, the front-rear direction, the left-right direction, and the up-down direction indicated by arrows in the drawings are respectively shown.

  As shown in FIG. 1, the printer 11 includes a transport unit 12 that transports a sheet P as a medium, a line head 13 that performs a printing process on the sheet P, and an ink supply unit that supplies ink as a fluid to the line head 13. 14, a maintenance unit 15, and a control device 100 (see FIG. 11).

  The transport unit 12 includes a pair of paper feed rollers 16, an endless transport belt 17, a drive roller 18, a driven roller 19, a drive motor 20 connected to the drive roller 18, and a pair of paper discharge rollers 21. It has. The conveying belt 17 is wound around the driving roller 18 and the driven roller 19, and rotates when the driving roller 18 rotates in the clockwise direction in FIG. The paper P is transported along the transport direction X by the paper feed roller 16, the transport belt 17, and the paper discharge roller 21. A plurality of (for example, two) conveyor belts 17 are provided so as to support at least both ends in the width direction Y (front-rear direction) of the paper P, and a maintenance unit is provided between the conveyor belts 17 arranged in the front-rear direction. 15 is arranged.

  The line head 13 includes a base portion 23 and a fluid ejecting head 24 supported by the base portion 23. As shown in FIG. 2, the fluid ejecting heads 24 are arranged in a staggered pattern so as to form two rows of lines extending along the width direction Y of the paper P. The first row located on the upstream side (left side) in the transport direction X is composed of four fluid ejection heads 24 arranged along the width direction Y, and is located on the downstream side (right side) in the transport direction X. The second row includes four fluid ejecting heads 24 arranged along the width direction Y.

  Each fluid ejecting head 24 is provided with a plurality of nozzles 25 for ejecting ink. Then, two nozzle rows N extending along the width direction Y are formed by the nozzle openings 25 a of the plurality of nozzles 25 on the nozzle forming surface 24 a formed from the lower surface (bottom surface) of the fluid ejecting head 24. As shown in the partially enlarged view of FIG. 2, in the two nozzle rows N, the nozzle openings 25a are arranged in a staggered manner so that the arrangement interval along the width direction Y is shifted by ½ pixel. In the first and second fluid ejecting heads 24, when projected in the transport direction X, at least one nozzle 25 at both ends overlaps or the nozzles 25 at both ends are continuous at a nozzle pitch. It has become.

  For this reason, the printer 11 can perform printing in the maximum paper width range even when the line head 13 is fixed. In the present embodiment, one fluid ejecting head 24 corresponds to 1.1 inches of paper, and the eight fluid ejecting heads 24 have an A4 size (297 mm long × 210 mm wide) width (about 8.3 inches). It comes to cover. One nozzle row N is composed of 330 nozzles 25. Therefore, one line head 13 is arranged along the width direction Y 8 (the number of fluid ejecting heads 24) × 2 (the number of nozzle rows N) × 330 (the number of nozzles 25 constituting the nozzle row N) = 5280. The nozzles 25 are provided.

  The line head 13 and the ink supply unit 14 are provided for each color, for example, when four colors of cyan (C), magenta (M), yellow (Y), and black (K) are printed. (FIGS. 1 and 2 show one by one for simplicity). Then, by printing four color ink droplets on the conveyed paper P from the four line heads 13, a printing process with a resolution of 600 dpi is possible.

  As shown in FIG. 1, the ink supply unit 14 includes a fluid supply source that stores ink, an ink cartridge 26 that serves as a fluid container, and a fluid supply path that supplies ink from the ink cartridge 26 toward the fluid ejection head 24. An ink supply tube 27 and a pressure pump 28 for supplying ink under pressure. The ink cartridge 26 is connected to the ink supply tube 27 by being detachably mounted on a cartridge holder (not shown). A pressure applying mechanism 29 and an opening / closing valve 95 are provided in the middle of the ink supply tube 27. The on-off valve 95 is an electromagnetic valve that can be arbitrarily opened and closed, and is provided immediately upstream of the pressure applying mechanism 29.

  A common ink chamber 30 that temporarily stores ink supplied from the ink cartridge 26 through the ink supply tube 27 is provided in the base portion 23 of the line head 13. A plurality of branch flow paths 31 corresponding to each fluid ejecting head 24 are connected to the common ink chamber 30. The ink stored in the common ink chamber 30 is supplied to the plurality of fluid ejecting heads 24 through the branch flow path 31.

  As shown in FIG. 3, the fluid ejecting head 24 includes a flow path forming member 32, a vibration plate 33, a flow path forming member 34, and a nozzle plate 35 that are stacked in the vertical direction. A branch channel 31 that communicates with the common ink chamber 30, a reservoir 36, and a storage chamber 37 are formed in the channel forming member 32. The diaphragm 33 is provided with a communication hole 38 at a position corresponding to the reservoir 36. A cavity 39 that communicates with the reservoir 36 through the communication hole 38 is formed in the flow path forming member 34.

  A piezoelectric element 40 is disposed on the upper surface side of the diaphragm 33 at a position above the cavity 39. A nozzle 25 communicating with the cavity 39 is formed in the nozzle plate 35. That is, the ink distributed from the common ink chamber 30 to each fluid ejecting head 24 through the branch flow path 31 is stored in the reservoir 36 and supplied from the reservoir 36 to each nozzle 25 through the communication hole 38 and the cavity 39.

  The diaphragm 33 is attached so as to vibrate in the vertical direction, and the piezoelectric element 40 expands and contracts in response to the drive signal, thereby vibrating the diaphragm 33 in the vertical direction. Further, when the vibration plate 33 vibrates in the vertical direction, the volume of the cavity 39 is expanded and contracted. When the volume of the cavity 39 is reduced, the ink in the cavity 39 is ejected from the nozzle 25 as an ink droplet Fb. The nozzle forming surface 24 a of the fluid ejecting head 24 is configured by the lower surface (bottom surface) of the nozzle plate 35. In this embodiment, the nozzle opening 25a has a diameter of about 20 micrometers, and the thickness of the nozzle plate 35 in the vertical direction is about 100 micrometers.

  Here, the ink cartridge 26 is provided at a position lower than the line head 13. Therefore, the region (ink flow path) in the fluid ejecting head 24 has a negative pressure of about −1 kPa due to a water head difference. This negative pressure is to prevent ink from dripping from the nozzle 25 and to form a concave meniscus in the nozzle 25 to stabilize the ejection operation.

Next, the maintenance unit 15 will be described.
The maintenance unit 15 includes a capping device 41 (see FIG. 4) for capping the nozzle forming surface 24a of the fluid ejecting head 24, a wiping device 42 (see FIG. 5) for wiping the nozzle forming surface 24a, and a nozzle inspection. The apparatus 101 (refer FIG. 11) is provided. The capping device 41 and the wiping device 42 may be provided for each fluid ejecting head 24, or a plurality of fluid ejecting heads 24 may be capped or wiped simultaneously.

  The capping device 41 is used for capping to prevent the nozzle 25 from drying, and performs suction cleaning for discharging bubbles, thickened ink, and the like by sucking ink in the ink cartridge 26 from the nozzle 25. Used when. Further, the capping device 41 is also used to receive ink discharged from the nozzle 25 during pressure cleaning in which the ink in the ink cartridge 26 is discharged from the nozzle 25 by the pressure pump 28. Hereinafter, the cleaning in which the ink in the ink cartridge 26 is discharged through the nozzle opening 25a while being supplied through the ink supply tube 27 will be referred to as “ink supply cleaning”.

  The wiping device 42 is used when wiping is performed for wiping the nozzle forming surface 24 a to remove deposits such as paper dust and ink, and for adjusting the meniscus of the nozzle 25. After the ink supply cleaning, the discharged ink adheres to the nozzle forming surface 24a or a convex meniscus is formed in the nozzle opening 25a. Therefore, wiping may be performed immediately after the ink supply cleaning. .

In addition, the nozzle inspection apparatus 101 inspects for the presence of defective nozzles that do not eject the required amount of ink.
First, the capping device 41 will be described.

  As shown in FIG. 4, the capping device 41 includes a bottomed square box-shaped cap 43, an elevating mechanism 44 that raises and lowers the cap 43, and a suction mechanism 45. A rectangular frame-shaped sealing member 46 made of a flexible material is provided on the entire upper surface of the peripheral wall of the cap 43, and a discharge pipe 47 is provided on the bottom wall of the cap 43 so as to protrude downward.

  One end of a discharge tube 48 made of a flexible material constituting the suction mechanism 45 is connected to the discharge pipe 47. The other end side of the discharge tube 48 is inserted into a waste ink tank 49. In the waste ink tank 49, a waste ink absorber 50 made of a porous member is accommodated.

  Between the cap 43 and the waste ink tank 49, a tube pump 51 constituting the suction mechanism 45 is disposed. The tube pump 51 includes a cylindrical case 52, a pump wheel 53 having a circular shape in plan view, a wheel shaft 54, and a pair of pressing rollers 55. The pump wheel 53 is accommodated in the case 52 so as to be rotatable around a wheel shaft 54 provided at the axial center of the case 52. Further, the intermediate portion of the discharge tube 48 is accommodated in the case 52 along the inner peripheral wall of the case 52.

  A pair of roller guide grooves 56 having an arc shape are formed in the pump wheel 53 so as to face each other with the wheel shaft 54 interposed therebetween. Each roller guide groove 56 has one end located on the inner peripheral side of the pump wheel 53 and the other end located on the outer peripheral side of the pump wheel 53. That is, both roller guide grooves 56 extend so as to gradually move away from the wheel shaft 54 from one end to the other end. Further, the pair of pressing rollers 55 is inserted and supported in both roller guide grooves 56 via a rotation shaft 57. Both the rotating shafts 57 are slidable in the roller guide grooves 56, respectively.

  When the pump wheel 53 is rotated in the forward direction (clockwise direction indicated by an arrow in FIG. 4), the pressing roller 55 moves forward to the other end side of the roller guide groove 56 (the outer peripheral side of the pump wheel 53). The middle portion of the discharge tube 48 rotates while being crushed sequentially from the upstream side to the downstream side. By this rotation, the inside of the discharge tube 48 upstream from the tube pump 51 is decompressed.

  Further, when the pump wheel 53 is rotated in the reverse direction (counterclockwise direction in FIG. 4), the pressing roller 55 moves in the backward direction to one end side of the roller guide groove 56 (inner peripheral side of the pump wheel 53). By this movement, both the pressing rollers 55 are in light contact with the intermediate portion of the discharge tube 48, and the reduced pressure state inside the discharge tube 48 is eliminated.

  The elevating mechanism 44 includes a cam member 58 that contacts the cap 43 from below, a motor 59 for rotating the cam member 58, and a power transmission mechanism 60. When the motor 59 is driven in the forward direction, the cam member 58 is rotated via the power transmission mechanism 60 so that the cap 43 comes into contact with the nozzle forming surface 24a.

  Accordingly, when the pump wheel 53 is driven in the positive direction with the cap 43 in contact with the nozzle forming surface 24a, a negative pressure is generated in the space region R surrounded by the cap 43 and the nozzle forming surface 24a. Thereby, the suction cleaning in which the ink is discharged from the nozzle 25 is executed. When the pump wheel 53 is driven in the reverse direction, the negative pressure in the space region R is eliminated. Therefore, when the motor 59 of the elevating mechanism 44 is subsequently driven in the reverse direction, the cap 43 is lowered, and the sheet Retreat from the P transport path.

  At the time of suction cleaning and pressure cleaning using the capping device 41, the tube pump 51 and the pressure pump 28 are driven after the on-off valve 95 is closed. Then, by opening the on-off valve 95 in a state where the pressure in the ink flow path is increased, the flow rate of the ink is increased and the bubble discharge property is improved.

Next, the wiping device 42 will be described.
As shown in FIG. 5, the wiping device 42 includes a wiping mechanism 61 and a lifting mechanism 62 that lifts and lowers the wiping mechanism 61.

  The wiping mechanism 61 includes a holder 63, a lead screw 64 installed on the holder 63 so as to extend in the front-rear direction, a motor 65 for rotating the lead screw 64, a support member 66, and an elastic body such as rubber. And a plate-like wiper 67 made of The wiper 67 is supported in a manner standing on the support member 66, and the support member 66 is supported by a lead screw 64. A storage recess 66 a is formed on the upper surface side of the support member 66.

  The elevating mechanism 62 includes a cam member 68 that contacts the holder 63 of the wiping mechanism 61 from below, a motor 69 for rotating the cam member 68, and a power transmission mechanism 70. When the motor 69 is driven in the forward direction, the cam member 68 is rotated via the power transmission mechanism 70, and the wiping mechanism 61 rises to a position where the wiper 67 contacts the nozzle forming surface 24a. ing.

  When the motor 65 is driven in the forward direction, the lead screw 64 rotates in the forward direction, and the wiper 67 moves along the front-rear direction together with the support member 66 in sliding contact with the nozzle forming surface 24a. Thereby, the wiping which cleans the nozzle formation surface 24a by wiping is performed. At this time, the ink or paper powder wiped from the nozzle forming surface 24a flows down through the wiper 67 and is stored in the storage recess 66a.

  Next, the pressure applying mechanism 29 will be described. The pressure application mechanism 29 performs “ink non-supply cleaning” that causes the ink in the fluid ejecting head 24 to bulge from the nozzle opening 25 a without supplying ink from the ink cartridge 26 side via the ink supply tube 27. Used to do.

  As shown in FIG. 6, the pressure applying mechanism 29 has a flow path forming member 71 having a regularity. A connecting portion 72 connected to the upstream ink supply tube 27 is provided at the left end of the flow path forming member 71, while a connecting portion connected to the downstream ink supply tube 27 is provided at the right end of the flow path forming member 71. 73 is provided. Further, a concave portion 71 a having a circular shape in plan view is formed on the upper surface side of the flow path forming member 71. In the connection portion 72, an inflow path 72a that connects the upstream ink supply tube 27 and the inside of the recess 71a is formed. On the other hand, in the connection portion 73, an outflow path 73a that connects the downstream ink supply tube 27 and the inside of the recess 71a is formed.

  On the upper surface side of the flow path forming member 71, a flexible film member 74 is fixed in a bent state so as to seal the opening of the recess 71a. In addition, a disc-shaped pressing plate 74a having an area smaller than the opening area of the recess 71a is fixed to a substantially central portion on the outer surface side of the film member 74. And the pressure chamber 75 is enclosed and formed by the film member 74 and the recessed part 71a. The pressure chamber 75 constitutes a part of the fluid supply path by communicating with the ink supply tube 27 through the inflow path 72a and the outflow path 73a.

  In the pressure chamber 75, a biasing member 76 that biases the film member 74 in a direction of expanding the internal volume of the pressure chamber 75 is disposed. The urging member 76 can be composed of, for example, a coil spring or a leaf spring. A cam member 77 that contacts the pressing plate 74a is disposed above the pressing plate 74a. The cam member 77 is supported via a rotation shaft 78 and rotates together with the rotation shaft 78 as the motor 79 is driven.

  Accordingly, when the motor 79 is driven in the forward direction in the state shown in FIG. 6A, the cam member 77 rotates counterclockwise in FIG. 6 against the urging force of the urging member 76. As a result, the film member 74 is displaced in a direction to decrease the internal volume of the pressure chamber 75 as shown in FIG. 6B, and the ink in the ink supply tube 27 is pressurized by the ink pushed out from the pressure chamber 75. The Further, when the motor 79 is driven in the reverse direction in the state shown in FIG. 6B, the cam member 77 rotates in the clockwise direction in FIG. As a result, the urging force of the urging member 76 displaces the film member 74 in the direction of increasing the internal volume of the pressure chamber 75, and the ink supply tube 27 is decompressed by the ink drawn into the pressure chamber 75.

Here, ink non-supply cleaning by the pressure applying mechanism 29 will be described in detail.
Ink non-supply cleaning is performed in a pressurizing step in which the pressure applying mechanism 29 pressurizes and bulges ink from the nozzle 25, and in a state where the ink bulges from the nozzle 25 due to pressurization after the pressurizing step. The pressure applying mechanism 29 includes a pressure reducing process for reducing pressure. That is, in the pressurizing step, the pressure applying mechanism 29 pushes the ink in the pressure chamber 75 at a stroke to propagate the pressure into the nozzle 25 and draws bubbles adhering to the inner wall of the nozzle 25 as shown in FIG. Peel off. Then, as shown in FIG. 7B, the bubbles are pushed out from the nozzle 25 to the atmosphere side outside the nozzle opening 25a.

  In the decompression step, the pressure applying mechanism 29 increases the volume of the pressure chamber 75, thereby pulling back the ink that has been pushed into the pressure chamber 75. As a result, before the ink droplet Fb is ejected or dropped (dropped) from the nozzle 25, the ink in a bulging state from the nozzle 25 is collected in the nozzle 25 as shown in FIG. . When the bubbles are discharged, a gap corresponding to the volume of the bubbles is generated in the nozzle 25, but when left for a short time, the ink in the common ink chamber 30 is caused to enter the nozzle 25 by capillary force as shown in FIG. To be replenished.

  By performing the pressurization and decompression of the ink non-supply cleaning repeatedly a plurality of times, bubbles that are difficult to be discharged can be gradually moved outward. For example, when pressurization and depressurization are repeated a plurality of times, not only the inside of the nozzle 25 but also the bubbles in the fluid ejecting head 24 and the common ink chamber 30 can be discharged. In addition, even when a gap is generated in the nozzle 25 as the bubbles are discharged, the liquid surface position of the nozzle 25 is gradually aligned by repeatedly performing pressurization and pressure reduction.

  In the decompression step, the volume decreased in the pressurization step may be returned to the original, or the volume increased for decompression may be made smaller than the volume decreased for pressurization. For example, when a relatively large bubble in the common ink chamber 30 is discharged by repeating pressurization and depressurization a plurality of times, there is a possibility that a nozzle omission occurs in which the entire nozzle 25 becomes a gap. When such nozzle omission occurs, it may be difficult to replenish ink by capillary force. Therefore, it is preferable to reduce the amount of ink drawn in, particularly at the time of final depressurization in which pressurization and depressurization are repeated a plurality of times.

  Here, as shown in FIG. 8, it is preferable that the depressurization time Td during which pressure is reduced in the depressurization step is set longer than the pressurization time Ta during which pressurization is performed in the pressurization step. Also, if the pressurization time Ta is too short, the ink droplet Fb is ejected by the propagating pressure and the ink is wasted, or the ink is pulled back before the air pressure is started and the bubbles are pushed out. There is a risk of getting lost. On the other hand, if the pressurization time Ta is too long, there is a possibility that the bubbles cannot be removed from the inner wall of the nozzle 25, or that the ink cannot be pulled back due to the reduced pressure and the ink is consumed.

  On the other hand, if the decompression time Td is too long, there is a risk that the ink will be consumed in the same time because the ink cannot be pulled back in time. Conversely, if the pressure reduction time Td is too short, air may be drawn from the outside of the nozzle 25 and bubbles may be generated.

  An appropriate pressurization time Ta for ensuring ejection of bubbles while suppressing ejection of the ink droplets Fb is a very short time, for example, 0.025 seconds to 0.2 seconds. On the other hand, if the pressure is reduced in such a short time, air is drawn in. Therefore, for the pressurization time Ta of 0.025 seconds to 0.2 seconds, the pressurization time Ta <the decompression time Td. preferable.

  In the present embodiment, pressurization and pressure reduction are performed by changing the volume of the pressure chamber 75 to such an extent that the ink droplet Fb is not ejected from the nozzle 25. Therefore, appropriate values for the amount of ink to be pushed out in accordance with the volume variation for pressurization (hereinafter referred to as “pressurized ink amount Vd”), pressurization time Ta, and decompression time Td are the nozzle 25 and the fluid. It fluctuates depending on flow path conditions such as the number of ejection heads 24 installed. Accordingly, the range of appropriate values for the pressurized ink amount Vd, the pressure time Ta, and the pressure reduction time Td and the flow path conditions will be described.

  As the flow path conditions of the printer 11 of this embodiment, as shown in FIG. 9, the internal volume (area No. 1) of the ink cartridge 26 is about 50 cc, and the internal volume of the ink supply tube 27 from the ink cartridge 26 to the pressure chamber 75. (Area No. 2) is about 3.5 cc. Further, the variable volume (region No. 3) of the pressure chamber 75 is about 1.0 cc, the internal volume (region No. 4) of the ink supply tube 27 on the downstream side of the pressure chamber 75 is about 1.9 cc, and the contents of the common ink chamber 30. The product (region No. 5) is about 3.1 cc, and the total internal volume (region No. 6) of the eight fluid ejecting heads 24 is about 0.9 cc.

  Here, in the ink non-supply cleaning, it is preferable that the ink pushed out from the pressure chamber 75 moves only to the downstream regions No 3 to No 6. Therefore, before the ink non-supply cleaning is performed, the open / close valve 95 is closed, and pressurization and decompression are performed. Under this flow path condition, the extruded ink can flow down only to the downstream side of the pressure chamber 75, and therefore, the regions No 3 to 6 excluding the regions No 1 and 2 in the regions shown in FIG. It becomes the influence range.

  Thus, FIG. 10A shows an appropriate range of the pressurized ink amount Vd when the ink non-supply cleaning is performed under the flow path condition in which the on-off valve 95 is closed. FIG. 10A shows the pressurization time Ta and the decompression time Td. The appropriate range is shown in FIG.

With respect to the pressurized ink amount Vd, it is preferable to pressurize by reducing the volume in the range of 0.18 cc ≦ Vd ≦ 0.48 cc in the volume of about 1.0 cc of the pressure chamber 75. If 0.18 cc> Vd, there is a possibility that a pressure sufficient to discharge bubbles may not be obtained, and if 0.48 cc <Vd, ink may be consumed. In this case, since one line head 13 is provided with 5280 nozzles 25, the good bulging area of ink per nozzle is approximately 3.5 × 10 ⁻⁵ cc to 9.0 × 10. ^-5 cc.

  Further, when 0.18 cc ≦ Vd ≦ 0.48 cc, the pressurization time Ta is 0.025 seconds ≦ Ta ≦ 0.2 seconds, and the decompression time Td is 0.1 seconds ≦ Td ≦ 0.5 seconds (however, Ta <Td) is preferred. It has been confirmed that particularly good results can be obtained by applying pressure at Vd = 0.33 cc and Ta = 0.15 seconds and reducing pressure at Td = 0.35 seconds.

  Ink non-supply cleaning by the pressure applying mechanism 29 does not cause ink to adhere to the nozzle forming surface 24a after execution, and the meniscus of the nozzle 25 can be adjusted, so that wiping is performed as post-processing like ink supply cleaning. There is no need. In addition, the ink consumption can be reduced to zero and can be performed in a very short time.

Next, the nozzle inspection apparatus 101 provided in the maintenance unit 15 will be described.
As shown in FIG. 11, the nozzle inspection apparatus 101 includes an electrode member 105 disposed in a cap 43 of the capping apparatus 41, and a voltage application circuit for applying a voltage between the electrode member 105 and the nozzle forming surface 24a. 106 and a voltage detection device 107.

  The electrode member 105 is formed as a lattice mesh made of a conductive material such as a metal such as stainless steel. The voltage detection device 107 includes an integration circuit 108 that integrates and outputs the detection signal from the electrode member 105, an inverting amplification circuit 109 that inverts and amplifies the signal output from the integration circuit 108, and an inverting amplification circuit 109. And an A / D conversion circuit 110 that performs A / D conversion on the output signal and outputs the signal to the control device 100.

  The voltage application circuit 106 includes a DC power supply (for example, 400 V) and a resistance element (for example, 1 MΩ) so that the electrode member 105 has a positive electrode and the nozzle forming surface 24a of the fluid ejecting head 24 has a negative electrode. Therefore, a positive charge is charged on the upper surface of the electrode member 105, while a negative charge is charged on the nozzle forming surface 24 a of the fluid ejecting head 24.

  In the printer 11, a nozzle inspection is performed by using the nozzle inspection apparatus 101 to inspect whether there is a defective nozzle that does not eject a required amount of ink. Below, this nozzle test | inspection is demonstrated.

  When the piezoelectric element 40 provided in the fluid ejecting head 24 is driven, the ink droplet Fb is ejected from the nozzle 25. At this time, since the negative charge is charged on the nozzle forming surface 24a, the negative charge is charged on the ink droplet Fb ejected from the nozzle 25.

  As the ink droplet Fb charged with a negative charge approaches the electrode member 105, the positive charge gradually increases on the electrode member 105 due to electrostatic induction. As a result, the potential difference between the electrode member 105 and the nozzle forming surface 24a of the fluid ejecting head 24 becomes larger than when the ink droplet Fb is not ejected from the nozzle 25 due to the induced voltage based on electrostatic induction.

  When the ink droplet ejected from the nozzle 25 lands on the electrode member 105, a part of the positive charge on the electrode member 105 is neutralized by the negative charge charged on the ink droplet. As a result, the potential difference between the electrode member 105 and the nozzle forming surface 24a becomes smaller than when no ink droplet is ejected from the nozzle 25. Thereafter, the potential difference between the electrode member 105 and the nozzle forming surface 24a returns to the initial size.

  Such a change in potential on the electrode member 105 side is input to the integration circuit 108 of the voltage detection device 107 as the voltage waveform signal V1. The voltage waveform signal V1 is inverted and amplified by the inverting amplifier circuit 109 and output as the voltage waveform signal V2. Further, the voltage waveform signal V2 is A / D converted by the A / D conversion circuit 110 and is converted into the voltage waveform signal V3. Is output.

  The control device 100 includes a CPU 150, a ROM 151, a RAM 152, and a nonvolatile memory 153 that function as selection means. The ROM 151 stores a control program executed by the CPU 150 and the like. Further, the RAM 152 temporarily stores calculation results of the CPU 150 and various data to be processed by executing the control program. The rewritable nonvolatile memory 153 stores an operation history of the printer 11 and the like.

  The CPU 150 detects the amplitude Wd of the voltage waveform signal V3 output from the voltage detection device 107, that is, the amount of change in the voltage value between the electrode member 105 and the nozzle formation surface 24a of the fluid ejection head 24 by calculation. Further, the CPU 150 determines whether or not the amplitude Wd is greater than or equal to an amplitude threshold value that is preset and stored in the ROM 151. The amplitude threshold is a value for estimating the ink ejection amount based on the voltage waveform signal V3 from the voltage detection device 107 and determining whether or not an appropriate amount of ink is ejected. Or the like in advance.

  That is, the amplitude Wd of the voltage waveform signal V3 changes depending on the presence or absence of the flying ink droplet Fb and its size. Therefore, when the nozzle 25 is clogged and ink droplets are not ejected, or when the amount of ink ejected is less than a predetermined amount, the amplitude of the output signal becomes smaller than in the normal case.

  Therefore, when the amplitude Wd of the voltage waveform signal V3 output from the voltage detection device 107 is equal to or greater than the amplitude threshold, the CPU 150 determines that the necessary amount of ink has been ejected. On the other hand, if the amplitude Wd of the voltage waveform signal V3 output from the voltage detection device 107 is smaller than the amplitude threshold, the CPU 150 determines that there is a defective nozzle that does not eject the required amount of ink.

  As described above, the nozzle inspection apparatus 101 performs the nozzle inspection by determining the presence or absence of a defective nozzle based on the amplitude Wd of the voltage waveform signal V3. Since the amplitude Wd of the voltage waveform signal V3 due to the ink droplets for one shot is extremely small, the voltage waveform signal V3 is changed to the ink for a plurality of shots by ejecting ink droplets for a plurality of shots (for example, three shots). Take out as integrated value by drop.

  The control device 100 further includes motor drive circuits 154 to 159, which are connected to the CPU 150, the ROM 151, the RAM 152, and the nonvolatile memory 153 via the bus 160. Then, the CPU 150 performs drive control of the pressurizing pump 28, the maintenance unit 15, the on-off valve 95, and the like.

  Specifically, the CPU 150 drives and controls the pump motor 96 of the pressurizing pump 28 via the motor driving circuit 154 and also drives and controls the motor 79 of the pressure applying mechanism 29 via the motor driving circuit 155. Further, the CPU 150 drives and controls a motor 59 for raising and lowering the cap 43 of the capping device 41 via the motor driving circuit 156, and rotates the pump wheel 53 of the capping device 41 via the motor driving circuit 157. The pump motor 97 is driven and controlled. Further, the CPU 150 drives and controls the motor 65 for moving the wiper 67 of the wiping device 42 in the front-rear direction via the motor drive circuit 158, and the motor 69 for raising and lowering the wiper 67 via the motor drive circuit 159. Is controlled. In addition, the CPU 150 performs open / close control of the open / close valve 95.

  When a defective nozzle is detected by nozzle inspection, the CPU 150 drives and controls the maintenance unit 15 and performs various cleanings.

Next, a cleaning operation in the printer 11 will be described.
The printer 11 according to the present embodiment selects any one of ink supply cleaning, non-ink supply cleaning, and wiping as a cleaning method so as to cope with each phenomenon that causes dot dropout, and executes the selected cleaning.

  Here, as shown in FIG. 12, a nozzle inspection is performed to determine which of the phenomena such as bubble mixing, clogging (nozzle 25 closing), and meniscus position receding that cause dot dropout. In some cases, this can be determined by checking the distribution of defective nozzles. For example, when Case 1 includes a plurality of defective nozzles adjacent to each other (hereinafter, such a state may be referred to as “group omission”), the ink supply is caused by replacement of the ink cartridge 26 or the like. It is presumed that relatively large bubbles were mixed from the upstream side of the tube 27.

  When bubbles are mixed and the inside of the nozzle 25 becomes hollow, even if the piezoelectric element 40 is driven, ink is not ejected and dot missing occurs. Further, dot omission may also occur due to vibration pressure propagation inhibition in which bubbles are buffered and pressure fluctuations accompanying driving of the piezoelectric element 40 are not properly transmitted. When large bubbles such as Case 1 are mixed from the upstream side, the defective nozzle often appears near the branch flow path 31, the reservoir 36, the communication hole 38, and the like.

  Further, as Case 2, when defective nozzles are locally distributed in the vicinity of the paper feed opening or the position where the end of the paper P passes, foreign matters such as paper dust attached to the end of the paper P to be conveyed It is estimated that clogging occurs due to adhering to the vicinity of the nozzle opening 25a. The paper P that has been cut to a predetermined size often has paper dust generated at the time of cutting attached to the edge that becomes the cutting part. This is because it scatters around it.

  Further, when wiping is performed as Case 3, the wiper 67 pushes air into the nozzle 25, and fine bubbles may be generated in the nozzle 25 (see FIG. 11). The bubbles in Case 3 are considerably smaller than bubbles mixed in when the ink cartridge 26 is replaced, and often remain near the nozzle 25. Since dot omission due to the mixing of bubbles occurs randomly, there may be cases where they are adjacent to each other by chance, but there are often cases where a single defective nozzle is dispersed.

  Also, as Case 4, when the meniscus moves backward due to the impact of opening the space region R to the atmosphere after suction cleaning, or when the wiper 67 comes into contact with the meniscus during wiping and the ink is drawn out from the nozzle 25, the ink into the nozzle 25 is discharged. Dosing may not occur in time and missing dots may occur. In Case 4, the meniscus is caught by a stepped portion near the nozzle 25 depending on the amount of discharged ink (see FIG. 11), so that defective nozzles are randomly generated.

  Further, as Case 5, even when the printer 11 is left unused for a long period of time, the ink is denatured or thickened by drying, resulting in clogging. Since clogging of Case 5 progresses from the nozzle opening 25a side (see FIG. 11), a plurality of defective nozzles often appear as a whole, but they randomly occur due to differences among the nozzles 25. . In addition, since there is a difference in the degree of progress of drying and thickening depending on the type of solvent and solute of the ink, there are colors that are likely to be clogged. For example, in the case of pigment ink, clogging due to thickening tends to occur in black (K). When clogging occurs due to the quality change of the ink, a color difference may occur due to the quality change. Therefore, it is preferable to execute the ink supply cleaning to discharge the quality changed ink.

  On the other hand, the defective nozzles of Cases 1 to 4 are not discharged (consumed) as much as possible because there is no problem with the ink itself. However, since the air bubbles mixed in with the replacement of the Case 1 ink cartridge 26 are large in size or located upstream of the pressure applying mechanism 29, the ink supply cleaning may not be able to be completely discharged. It is preferable to perform cleaning. In addition, it is difficult to determine the generation factors of Cases 2 to 5 (particularly Cases 3 to 5) only by the distribution of defective nozzles.

  Further, the occurrence of clogging due to the mixing of bubbles due to the replacement of the ink cartridge 26 of Case 1 and the leaving of Case 5 is lower than the phenomenon of Cases 2 to 4. For this reason, the printer 11 selectively performs ink supply cleaning only for a phenomenon that cannot be resolved without consuming ink, while performing cleaning that does not involve ink consumption for other relatively frequent phenomena. Thus, ink consumption associated with cleaning is suppressed. In particular, the line head type printer 11 as in the present embodiment has a large number of nozzles 25, and the amount of ink consumed for ink supply cleaning increases. Therefore, by selectively executing the non-ink supply cleaning, it is possible to maintain the print quality while suppressing the ink consumption.

Next, a cleaning method selection process performed by the CPU 150 will be described with reference to FIG.
As shown in FIG. 13, when the control device 100 receives a nozzle inspection execution command, the nozzle inspection device 101 executes a nozzle inspection, and the CPU 150 performs a cleaning method (wiping, ink supply cleaning, and ink non-supply based on the inspection result). Select either cleaning). That is, the cleaning method of the present embodiment includes a selection step of selecting any one of wiping, ink supply cleaning, and ink non-supply cleaning. The nozzle inspection is performed at a predetermined timing such as when the printer 11 is turned on (powered on), in a standby state after a predetermined time has elapsed since the previous cleaning, or when the user operates a nozzle inspection execution instruction. Is executed.

  First, when nozzle inspection is executed in step S11, in step S12, the CPU 150 determines whether there is a defective nozzle that does not eject a required amount of ink. As a result, when there is no defective nozzle, the CPU 150 determines NO and ends the process. On the other hand, if there is a defective nozzle, the CPU 150 determines YES and proceeds to step S13.

  In step S13, the CPU 150 determines whether or not there are a plurality of defective nozzles adjacent to each other. If there are a plurality of defective nozzles adjacent to each other, the CPU 150 determines YES to select ink supply cleaning, and proceeds to step S14. This is because it is presumed that the case 1 phenomenon has occurred when the “group omission” adjacent to the defective nozzle occurs.

  In step S14, the CPU 150 executes suction cleaning or pressure cleaning as ink supply cleaning. When performing the suction cleaning, the CPU 150 drives and controls the motor 59, the pump motor 97, and the on-off valve 95 of the capping device 41, and discharges the ink in the fluid ejecting head 24 from the nozzle opening 25a. Alternatively, when performing pressure cleaning, the CPU 150 drives and controls the pump motor 96 and the on-off valve 95 of the pressure pump 28 to discharge the ink in the fluid ejecting head 24 from the nozzle openings 25a.

  Since the meniscus is often disturbed after the ink supply cleaning is performed, the CPU 150 selects the ink non-supply cleaning and proceeds to step S15. Then, in step S15, the CPU 150 drives and controls the motor 79 of the pressure applying mechanism 29, executes ink non-supply cleaning, and adjusts the meniscus, and then the process ends.

  If there is only one defective nozzle in step S13, or if there are a plurality of defective nozzles but they are not adjacent to each other, the CPU 150 determines NO and proceeds to step S16 to perform nozzle inspection. A cleaning method is selected based on the operation of the printer 11 immediately before the start (before cleaning). This is because it is difficult to determine the generation factors of Cases 2 to 5 only by the distribution of defective nozzles.

  Specifically, in step S16, when the operation immediately before the printer 11 is power ON (startup) or replacement (detachment) of the ink cartridge 26, the CPU 150 selects ink supply cleaning and proceeds to step S14. . In step S14, the CPU 150 executes ink supply cleaning (suction cleaning or pressure cleaning). Thereafter, the CPU 150 selects non-ink supply cleaning and proceeds to step S15. In step S15, the CPU 150 executes the ink non-supply cleaning to adjust the meniscus, and then ends the process.

  In step S16, if the operation immediately before the printer 11 is ink supply cleaning, the CPU 150 selects ink non-supply cleaning and proceeds to step S15. In step S15, the CPU 150 executes the ink non-supply cleaning to adjust the meniscus, and then ends the process.

  In step S16, if the operation immediately before the printer 11 is printing (printing process), the CPU 150 selects wiping as the cleaning method and proceeds to step S17. In step S <b> 17, the CPU 150 drives and controls the motors 65 and 69 of the wiping device 42 to execute wiping for wiping off paper dust and the like attached to the nozzle forming surface 24 a with the wiper 67.

  It should be noted that minute bubbles may be pushed into the nozzle 25 after the wiping is performed. Therefore, when the operation immediately before the printer 11 is wiping by the wiping mechanism 61, the CPU 150 selects ink non-supply cleaning and proceeds to step S15. In step S15, the CPU 150 performs ink non-supply cleaning and ends the process.

  As described above, in the printer 11 of the present embodiment, the CPU 150 selectively executes the cleaning method based on the inspection result of the nozzle inspection and the operation of the printer before cleaning, thereby reducing the number of times of ink supply cleaning. To the limit. Therefore, ink consumption associated with cleaning is suppressed.

According to the embodiment described above, the following effects can be obtained.
(1) When the CPU 150 selects ink non-supply cleaning, the fluid ejection head 24 can be cleaned while suppressing ink consumption. That is, by selectively performing the ink non-supply cleaning instead of the ink supply cleaning that consumes ink, the fluid ejecting head 24 can be cleaned while suppressing ink consumption.

  (2) When there is a defective nozzle when the power is turned on, it is highly possible that the ink staying in the nozzle 25 has changed in quality. For this reason, by performing ink supply cleaning when a defective nozzle is detected in the inspection when the power is turned on, the deteriorated ink in the nozzle 25 can be discharged.

  (3) Since the CPU 150 selects a cleaning method based on the operation of the printer 11 before cleaning, it can selectively execute either ink non-supply cleaning or ink supply cleaning according to the situation. .

  (4) Since the ink supply cleaning is executed when the operation immediately before the printer 11 is attachment / detachment of the ink cartridge 26, the large bubbles mixed in the ink supply tube 27 with the attachment / detachment of the ink cartridge 26 are combined with the ink. Can be discharged.

(5) Since the ink non-supply cleaning is executed after the ink supply cleaning is executed, the meniscus in the nozzle 25 disturbed by the discharge of the ink can be adjusted.
(6) Since the ink non-supply cleaning is performed after the wiping is performed, the meniscus in the nozzle disturbed by the wiping can be adjusted, or the air bubbles pushed into the nozzle 25 can be discharged.

  (7) When the pressure applying mechanism 29 pressurizes the ink in the ink supply tube 27, a part of the ink is swelled from the nozzle 25, and bubbles mixed in the swelled part of the ink are removed. It can extrude to the atmosphere side which becomes the outer side of the nozzle opening 25a. Further, when the pressure application mechanism 29 continuously reduces the pressure, the fluid ejection is performed so that the ink swelled from the nozzle 25 due to the pressurization is not wasted by dropping from the nozzle opening 25a. It can be pulled back into the head 24. Therefore, according to the ink non-supply cleaning by the pressure applying mechanism 29, it is possible to discharge bubbles while suppressing ink consumption.

  (8) Pressurization is performed in a short time to ensure bubble discharge and the decompression time Td is longer than the pressurization time Ta, thereby suppressing the entrainment of bubbles from the nozzle opening 25a.

  (9) Since the pressure applying mechanism 29 reduces the volume of the pressure chamber 75, the ink corresponding to the reduced volume can be pushed out and the pressure can be applied to the nozzle 25 side. Further, since the pressure reduction is performed by increasing the volume of the pressure chamber 75, the pressure reduction can be continuously performed with the pressure by returning the volume reduced for the pressurization.

  (10) When air bubbles are discharged from the nozzle 25 along with the pressurization, a gap is generated in the nozzle 25 correspondingly, but the pressure chamber 75 that is increased for pressure reduction reduces the volume of the pressure chamber 75 for pressurization. By making it smaller than the volume of the chamber 75, it is possible to suppress the occurrence of nozzle omission due to the gap.

  (11) By adjusting the back pressure of each nozzle 25 in the common ink chamber 30, the meniscus of the nozzle 25 can be uniformly adjusted. For example, the flow of ink accompanying the pressurization or decompression of the ink non-supply cleaning is spilled into the nozzle 25 via the common ink chamber 30. Therefore, even when a gap is generated in one nozzle 25 from which bubbles are discharged, the liquid surface position is aligned with the other nozzles 25 by repeating pressurization and pressure reduction. Since the pressure applying mechanism 29 is provided upstream of the common ink chamber 30 in the ink flow path, the configuration is not complicated even when the number of fluid ejecting heads 24 is increased.

  (12) Since the pressurization time Ta during which the pressure applying mechanism 29 performs pressurization is a very short time from 0.025 seconds to 0.2 seconds, the bubbles attached to the inner wall of the nozzle 25 are peeled off and discharged. Can do.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 14, in the ink supply unit 14 </ b> A of the printer 11 </ b> A of the present embodiment, a differential pressure valve 80 is disposed between the ink cartridge 26 of the ink supply tube 27 and the open / close valve 95. A pressure applying mechanism 29 </ b> A is provided on the downstream side of the on-off valve 95.

First, the pressure applying mechanism 29A will be described.
As shown in FIG. 15, the pressure application mechanism 29 </ b> A according to the present embodiment includes a flow path forming member 91 having a regular shape. A connecting portion 92 connected to the ink supply tube 27 is provided at the left end of the flow path forming member 91, while a connecting portion 93 connected to the ink supply tube 27 is provided at the right end of the flow path forming member 91. Further, a concave portion 91 a having a circular shape in plan view is formed on the upper surface side of the flow path forming member 91. An inflow path 92 a that connects the ink supply tube 27 and the recess 91 a is formed in the connection portion 92. On the other hand, in the connection portion 93, an outflow passage 93a that connects the ink supply tube 27 and the recess 91a is formed.

  A piston 94 is slidably accommodated in the recess 91 a of the flow path forming member 91. One end side (lower end side) of the piston 94 constitutes a disc-shaped movable portion 94a constituting one wall surface of the pressure chamber 75, and the other end side (upper end side) of the piston 94 constitutes a disc-shaped pressure receiving portion 94b. . The pressure chamber 75 is surrounded by the movable portion 94 a of the piston 94 and the recess 91 a of the flow path forming member 91.

  An urging member 76 made of a spring is disposed between the upper surface side of the flow path forming member 91 and the lower surface side of the pressure receiving portion 94b. Therefore, when the motor 79 is driven in the forward direction and the cam member 77 is rotated in the counterclockwise direction in the drawing, the movable portion 94a of the piston 94 is moved away from the rotating shaft 78. Then, the volume of the pressure chamber 75 decreases, and the ink in the ink supply tube 27 is pressurized by the ink pushed out from the pressure chamber 75. Further, when the motor 79 is driven in the reverse direction and the cam member 77 is rotated in the clockwise direction in the drawing, the movable portion 94a of the piston 94 is moved in the direction close to the rotating shaft 78 by the urging force of the urging member 76. To do. Then, the volume of the pressure chamber 75 increases, and the ink supply tube 27 is depressurized by the ink drawn into the pressure chamber 75.

Next, the differential pressure valve 80 will be described.
The differential pressure valve 80 is a diaphragm-type self-sealing valve that opens and closes using a differential pressure between atmospheric pressure and ink pressure, and is disposed between the ink cartridge 26 and the open / close valve 95. Further, in the printer 11 </ b> A, the ink cartridge 26 (cartridge holder not shown) is provided at a position higher than the line head 13. For this reason, the pressure inside the fluid ejecting head 24 is set to a negative pressure of about −1 kPa by the differential pressure valve 80.

  As shown in FIG. 16A, the differential pressure valve 80 has a flow path forming member 82 having a regularity. A connecting portion 83 connected to the upstream ink supply tube 27 is provided at the left end of the flow path forming member 82, while a connecting portion connected to the downstream ink supply tube 27 is provided at the right end of the flow path forming member 82. 84 is provided. Further, a concave portion 82a having a circular shape in plan view is formed on the upper surface side of the flow path forming member 82, and a convex portion 82b having a truncated cone shape is formed at a position eccentric to the left from the center on the inner bottom surface of the concave portion 82a. One is formed. In addition, an inflow path 83a is formed in the connection portion 83 to communicate the upstream ink supply tube 27 and the recess 82a so that an opening into the recess 82a is formed at the upper end surface of the projection 82b. ing. On the other hand, in the connecting portion 84, an outflow path 84a that connects the downstream ink supply tube 27 and the inside of the recess 82a is formed.

  On the upper surface side of the flow path forming member 82, a flexible film member 85 is fixed in a bent state so as to seal the opening of the recess 82a. In addition, a disc-shaped pressing plate 86 having an area smaller than the opening area of the recess 82a is fixed to a substantially central portion on the inner surface facing the recess 82a of the film member 85. A pressure chamber 87 is surrounded by the film member 85 and the recess 82a.

  In the pressure chamber 87, a base portion 88, an arm member 89 supported by the base portion 88 so as to be tiltable, and one end side (left end side) of the arm member 89 are attached to the convex portion 82b side. An energizing spring 90 is accommodated. The arm member 89 normally receives the urging force of the urging spring 90, and one end side seals the opening of the inflow passage 83a provided on the upper end surface of the convex portion 82b, and the other end side (right end side) is pressed. The plate 86 is pushed upward. As a result, the film member 85 is deflected and displaced in the direction in which the internal volume of the pressure chamber 87 is enlarged, and the pressure in the pressure chamber 87 and the fluid ejecting head 24 located in the downstream area thereof becomes a negative pressure of about −1 kPa.

  Further, ink is supplied to the inflow passage 83a in a pressurized state by the pressurizing pump 28, and is always introduced into the pressure chamber 87 by one end side of the arm member 89 that receives the biasing force of the biasing spring 90. Inflow is suppressed. Then, when ink is consumed by ejection or outflow from the nozzle 25, the negative pressure in the pressure chamber 87 increases, and the film member 85 resists the urging force of the urging spring 90 as shown in FIG. Thus, the pressure chamber 87 is deflected and displaced in the direction of decreasing the internal volume. Then, the other end side of the arm member 89 is pressed and tilted by the film member 85 via the pressing plate 86, and the one end side opens the opening of the inflow path 83a, so that the pressure chamber 87 is pressurized through the inflow path 83a. Ink flows in.

  When the negative pressure in the pressure chamber 87 decreases with the inflow of ink, the arm member 89 and the film member 85 are returned to their original positions by the biasing force of the biasing spring 90 again. Therefore, ink corresponding to the amount of consumption is supplied to the fluid ejecting head 24.

Next, cleaning method selection processing by the CPU 150 will be described with reference to FIGS. 17 and 18.
As shown in FIG. 17, when the control device 100 receives a nozzle inspection execution command, the nozzle inspection device 101 executes a nozzle inspection in step S21. In step S22, the CPU 150 determines whether there is a defective nozzle that does not eject the required amount of ink. As a result, when there is no defective nozzle, the CPU 150 determines NO and ends the process. On the other hand, if there is a defective nozzle, the CPU 150 determines YES and proceeds to step S23.

  In step S23, the CPU 150 determines whether or not there are a plurality of defective nozzles adjacent to each other. If there are a plurality of defective nozzles adjacent to each other, the CPU 150 determines YES to select ink supply cleaning, and the process proceeds to step S24. This is because it is presumed that the case 1 phenomenon has occurred when the “group omission” adjacent to the defective nozzle occurs. In step S24, the CPU 150 executes suction cleaning or pressure cleaning as ink supply cleaning.

  Since the meniscus is often disturbed after the ink supply cleaning is performed, the CPU 150 selects the ink non-supply cleaning after the ink supply cleaning is performed, and the process proceeds to step S25. In step S25, the CPU 150 completes the meniscus by executing non-ink supply cleaning, and then ends the process.

  On the other hand, if there is only one defective nozzle in step S23 or if a plurality of defective nozzles are not adjacent to each other, the CPU 150 determines NO and selects ink non-supply cleaning, and proceeds to step S25. . This is because when any defective nozzle is present at random, it is presumed that any of the cases 2 to 5 has occurred. In step S <b> 25, the CPU 150 ends the process after executing the ink non-supply cleaning.

  It should be noted that the ink supply cleaning is performed only when “missing group” is detected in the nozzle inspection, so that it is not limited to the case where the ink cartridge 26 is attached / detached, but large bubbles or relatively severe air bubbles over the plurality of nozzles 25 are also present. Ink supply cleaning can be selectively performed when clogging occurs. On the other hand, when defective nozzles are not adjacent to each other, relatively small bubbles and slight clogging are factors, and therefore, dot missing can be eliminated by ink non-supply cleaning.

  Further, the selection of the cleaning method by the CPU 150 is not limited to the case of the nozzle inspection, but may be performed when the control device 100 receives a cleaning execution command as shown in FIG. In this case, when the control device 100 receives the nozzle inspection execution command, in step S31, the CPU 150 selects a cleaning method based on the operation of the printer 11 immediately before (before cleaning).

  Specifically, in step S31, when the operation of the previous printer 11 is power ON (startup), the process proceeds to step S32, and the nozzle inspection apparatus 101 executes the nozzle inspection apparatus. Subsequently, in step S33, the CPU 150 determines whether there is a defective nozzle that does not eject the required amount of ink. As a result, when there is no defective nozzle, the CPU 150 determines NO and ends the process. On the other hand, if there is a defective nozzle, the CPU 150 determines YES and proceeds to step S34.

  In step S34, the CPU 150 selects ink supply cleaning as the cleaning method. That is, when a defective nozzle is detected after the power is turned on, it is presumed that clogging due to the deterioration of Case 5 ink has occurred, so the ink supply cleaning is executed to discharge the deteriorated ink. In addition, after the ink supply cleaning is executed, the CPU 150 selects the ink non-supply cleaning to proceed to step S35 in order to adjust the meniscus disturbed by the ink discharge. In step S35, the CPU 150 performs ink non-supply cleaning, and thereafter ends the process.

  If the operation immediately before the printer 11 is the replacement of the ink cartridge 26 in step S31, the CPU 150 selects ink supply cleaning as the cleaning method and proceeds to step S34. In step S34, the CPU 150 performs ink supply cleaning. Thereafter, the process proceeds to step S35 in order to correct the meniscus disturbed by the ink discharge. In step S35, the CPU 150 executes ink non-supply cleaning, and thereafter ends the process.

  In step S31, if the operation immediately before the printer 11 is printing (printing process), the CPU 150 selects ink non-supply cleaning as the cleaning method, and the process proceeds to step S35. This is to prevent foreign matter such as paper dust from entering and accumulating in the nozzles 25 by performing ink non-supply cleaning. In step S35, the CPU 150 executes ink non-supply cleaning, and thereafter ends the process. As a result, it is possible to prevent the accumulated foreign matter from adhering in the nozzle 24 as the ink thickens and becoming clogged.

According to the embodiment described above, the following effects can be obtained in addition to the same effects as the above (1) to (5) and (7) to (12).
(13) When a plurality of defective nozzles that do not eject the required amount of ink are adjacent to each other, ink supply cleaning is executed, so that relatively severe clogging can be eliminated while supplying ink. Large bubbles over the nozzles can be discharged. On the other hand, even if there are a plurality of defective nozzles, if they are not adjacent to each other, the ink non-supply cleaning is executed. Therefore, by causing the ink to bulge out from the nozzle opening 25a, the expansion of the ink is performed. Bubbles mixed in the protruding portion can be pushed out to the atmosphere side outside the nozzle opening 25a. In other words, by selectively performing the ink non-supply cleaning, small bubbles in the nozzle can be discharged while suppressing ink consumption.

The above embodiment may be changed to another embodiment as described below.
-Wiping may not be an option as a cleaning method. For example, when a film that does not easily generate foreign substances such as paper dust is used as a medium for receiving fluid, or when a fluid that does not thicken easily is ejected, the nozzle 25 is not easily clogged. It is not necessary to perform.

  In the cleaning method selection process shown in FIG. 18, when the operation immediately before the printer 11 is printing (printing process) in step S31, the CPU 150 may select wiping as the cleaning method.

  -The presence or absence of a defective nozzle can be inspected by any method. For example, it may be inspected based on whether or not the laser beam irradiated by the ejected ink droplet is blocked, or a test print may be performed to inspect the presence or absence of missing dots by the user's visual observation. .

  The criteria for determining whether or not “group missing” may be changed depending on the type of fluid, the configuration of the printer 11, and the like. For example, when three or more defective nozzles are adjacent to each other, it may be determined that “group missing” is detected, or when a plurality of defective nozzles exist within a predetermined range, “group missing” is determined. You may make it judge that there exists. Alternatively, even if two defective nozzles are adjacent to each other, if there are no other defective nozzles, ink non-supply cleaning may be selected.

  The wiping may be executed after the ink supply cleaning is executed, and the ink non-supply cleaning may be executed after the wiping is executed. Thereby, the micro bubble pushed into the nozzle 25 by wiping can be discharged | emitted.

  Not only based on a cleaning execution command or a nozzle inspection execution command, the nozzle inspection device 101 performs nozzle inspection when the power is turned on, and when a defective nozzle is detected, the CPU 150 selects and executes ink supply cleaning. It may be. If there is a defective nozzle when the power is turned on, it is highly possible that the ink that has stayed in the nozzle 25 has changed in quality. For this reason, by performing ink supply cleaning when a defective nozzle is detected in the inspection when the power is turned on, the deteriorated ink in the nozzle 25 can be discharged.

In the printers 11 and 11A, the ink non-supply cleaning may be executed with the on-off valve 95 opened.
The printer 11 may execute the selection of the cleaning method shown in FIGS. 17 and 18, or the printer 11A may execute the selection of the cleaning method shown in FIG.

  -It is good also as a structure which is not provided with the pressure provision mechanisms 29 and 29A. In this case, a part of the ink can be swollen from the nozzle 25 by performing a short-time suction with the capping device 41. Further, if the negative pressure in the space region R is eliminated while the ink is bulged from the nozzle 25, the bulged ink can be returned to the nozzle 25 without being consumed.

  In the pressure applying mechanism, the piston 94 of the pressure applying mechanism 29A may be configured with a movable iron core, and a solenoid may be provided around it. In this case, the piston 94 made of a movable iron core can be moved by causing a current to flow through the solenoid to generate a magnetic field.

The pressure applying mechanism may include a piezoelectric element, and pressurization or decompression may be performed by changing the volume of the fluid supply path using the piezoelectric element.
The pressure may be applied by crushing the elastically deformable ink supply tube 27 with the cam member 77. In this case, since the pressure applying mechanism does not have to include a flow path forming member or the like, the configuration can be simplified.

  The common ink chamber 30 is not provided, and for example, one end side (base end side) of the ink supply tube 27 is connected to the ink cartridge 26, while the other end side (tip end side) branches into a plurality of fluid ejecting heads 24. You may make it connect. In this case, the pressure applying mechanisms 29 and 29A may be provided on the proximal end side, or the pressure applying mechanisms 29 and 29A may be provided on the branched distal end side.

The pressure application mechanism may be provided between the common ink chamber 30 and the reservoir 36, or may be provided between the reservoir 36 and the cavity 39.
The liquid supply path may be configured from a rigid pipe line that is not easily elastically deformed. In this case, the pressure fluctuation accompanying pressure reduction in the pressurization step and pressure reduction in the pressure reduction step can be propagated into the nozzle 25 without being absorbed by the elastic deformation of the pipe line.

  When the flow path condition or the fluid to be ejected is changed, the frictional resistance, flow path resistance, viscosity, etc. change, so that the pressurized ink amount Vd, the pressurizing time Ta, and the depressurizing time Td in the ink non-supply cleaning are also respectively It is preferable to change to an appropriate value.

The number of fluid ejecting heads 24 and nozzles 25, the number of nozzle rows N, and the like can be arbitrarily set.
A non-removable ink tank may be adopted as the fluid container.

-You may implement | achieve as a full line type line head type printer provided with a long fluid ejection head, a lateral type printer, or a serial type printer.
In the above embodiment, the fluid ejecting apparatus is embodied as an ink jet printer, but a fluid ejecting apparatus that ejects or ejects fluid other than ink may be employed, and a minute amount of liquid droplets is ejected. The present invention can be applied to various liquid ejecting apparatuses including a liquid ejecting head to be used. In addition, a droplet means the state of the liquid discharged from the said liquid ejecting apparatus, and shall also include what pulls a tail in granular shape, tear shape, and thread shape. The liquid here may be any material that can be ejected by the liquid ejecting apparatus. For example, it may be in the state when the substance is in a liquid phase, such as a liquid state with high or low viscosity, sol, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, liquid metals (metal melts ) And a liquid as one state of a substance, as well as a material in which particles of a functional material made of a solid such as a pigment or metal particles are dissolved, dispersed or mixed in a solvent. Further, representative examples of the liquid include ink and liquid crystal as described in the above embodiment. Here, the ink includes general water-based inks and oil-based inks, and various liquid compositions such as gel inks and hot melt inks. As a specific example of the liquid ejecting apparatus, for example, a liquid containing a material such as an electrode material or a color material used for manufacturing a liquid crystal display, an EL (electroluminescence) display, a surface emitting display, a color filter, or the like in a dispersed or dissolved state. It may be a liquid ejecting apparatus for ejecting, a liquid ejecting apparatus for ejecting a bio-organic material used for biochip manufacturing, a liquid ejecting apparatus for ejecting a liquid as a sample used as a precision pipette, a textile printing apparatus, a microdispenser, or the like. In addition, transparent resin liquids such as UV curable resin to form liquid injection devices that pinpoint lubricant oil onto precision machines such as watches and cameras, and micro hemispherical lenses (optical lenses) used in optical communication elements. A liquid ejecting apparatus that ejects a liquid onto the substrate or a liquid ejecting apparatus that ejects an etching solution such as an acid or an alkali to etch the substrate may be employed. The present invention can be applied to any one of these injection devices.

  DESCRIPTION OF SYMBOLS 11, 11A ... Printer as fluid ejecting apparatus, 24 ... Fluid ejecting head, 24a ... Nozzle formation surface, 25a ... Nozzle opening, 26 ... Ink cartridge as fluid supply source and fluid container, 27 ... Construct fluid supply path Ink supply tube, 61... Wiping mechanism, 101... Nozzle inspection device, 150.

Claims (7)

A fluid ejecting head provided with a plurality of nozzle openings for ejecting fluid; and
A fluid supply path for supplying the fluid from the fluid supply source side toward the fluid ejection head side;
As a method of cleaning the fluid ejecting head, a fluid that causes the fluid in the fluid ejecting head to bulge from the nozzle opening without supplying the fluid from the fluid supply source side through the fluid supply path. Selection of non-supply cleaning and fluid supply cleaning to be discharged from the nozzle opening while supplying the fluid from the fluid supply source side via the fluid supply path based on the operation before the cleaning is performed And a fluid ejecting apparatus. The fluid supply source is a fluid container that is detachably attached to an upstream end of the fluid supply path,
The fluid ejecting apparatus according to claim 1 , wherein the selection unit selects the fluid supply cleaning when the operation immediately before the fluid ejecting apparatus is attachment / detachment of the fluid container. Said selecting means, if the last action of the fluid ejection device was the fluid supply cleaning fluid ejection according to claim 1 or claim 2, characterized in that selecting the fluid not supplied cleaning apparatus. A wiping mechanism for wiping the nozzle forming surface in which the nozzle opening is formed in the fluid ejecting head;
It said selecting means, if the last action of the fluid ejection device were the wiping by the wiping mechanism, which of claims 1 to 3, characterized by selecting the fluid not supplied cleaning The fluid ejecting apparatus according to claim 1. A nozzle inspection device for inspecting the presence or absence of a defective nozzle that does not eject the required amount of fluid;
The selection means selects the fluid supply cleaning when a plurality of the defective nozzles are adjacent to each other based on the result of the inspection, while the plurality of the defective nozzles are not adjacent to each other. The fluid ejecting apparatus according to claim 1, wherein the fluid non-supply cleaning is selected. The nozzle inspection device performs the inspection at power-on,
The fluid ejecting apparatus according to claim 5 , wherein the selection unit selects the fluid supply cleaning when the defective nozzle is detected in the inspection at the time of turning on the power. As a method of cleaning a fluid ejecting head provided with a plurality of nozzle openings for ejecting fluid,
Fluid non-supply cleaning for causing the fluid in the fluid ejecting head to bulge from the nozzle opening without supplying the fluid from the fluid supply source side through the fluid supply path toward the fluid ejecting head side. Any one of the fluid supply cleanings for discharging the fluid in the fluid ejecting head from the nozzle opening while supplying the fluid from the fluid supply source side through the fluid supply path is an operation before the cleaning is performed. A cleaning method comprising a selection step of selecting based on the method.

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