JP6597257B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus.

  2. Description of the Related Art Conventionally, there is an ink jet recording apparatus that performs image recording and formation of a three-dimensional structure by ejecting ink droplets and landing on a recording medium in a desired pattern. In this ink jet recording apparatus, a technique is used in which ink droplets are ejected from a nozzle at a desired amount and speed by pressurizing ink with an appropriate pressure change pattern.

  At this time, if foreign matters such as dust and dust are mixed in the ink, the quality of the recorded image and the formed structure is deteriorated. Therefore, in the inkjet head, before the ink supplied from the ink tank reaches the nozzles, for example, a filter for removing these foreign substances is provided in a common flow path or a common ink chamber immediately before the ink is distributed to each nozzle. It has been.

  On the other hand, when air bubbles are mixed in the ink, there is a problem that pressure is not properly applied to the ink due to the air bubbles, resulting in ink ejection failure. On the other hand, there is a technique for removing bubbles in the ink flow path by pressurizing and forcibly discharging or circulating the ink in the ink flow path. In Patent Document 1, a three-way valve is provided at a merging position of a circulation flow path for returning ink to an ink tank from an upstream side and a downstream side of a filter provided in an ink liquid filling unit in a recording head. A technique is disclosed in which such ink is controlled to flow to the ink tank and bubbles are removed as necessary. Further, in Patent Document 2, a first bubble removal path and a second bubble removal path via a filter are respectively provided above the first liquid chamber on the upstream side and the second liquid chamber on the downstream side of the filter in the recording head. There is disclosed a technique for sequentially discharging bubbles generated in each nozzle while adjusting the flow rate so as not to destroy the ink meniscus in the nozzle.

JP 2010-221589 A JP 2012-218398 A

  However, when the ink flow is used to remove bubbles on the downstream side of the filter provided in the recording head, a part of the ink leaks from the nozzle. As a result, there is a problem that a lot of ink is wasted.

  An object of the present invention is to provide an ink jet recording apparatus capable of easily reducing the amount of wasted ink while reliably removing bubbles.

In order to achieve the above object, the invention according to claim 1
A recording head having a nozzle for ejecting ink and an ink flow path for supplying ink to the nozzle ;
A liquid feeding section that applies pressure to the ink and feeds the ink to the ink flow path; and
A control unit for operating the liquid feeding unit ;
With
In the ink flow path, an inflow port through which ink supplied from outside flows in, a filter for filtering the ink that flows in from the inflow port, a communication port to the output flow path that communicates with the nozzle, and the ink flow out An ink chamber having a first outlet and a second outlet to be provided;
The ink chamber includes the inlet and the first outlet by the filter, and includes an upstream ink chamber through which ink not passing through the filter flows, the second outlet and the communication port, It is divided into a downstream ink chamber through which the ink that has passed through the filter flows,
The downstream ink chamber is provided with a channel narrowing member that narrows the area of the channel cross section perpendicular to the ink flow to the second outlet in a range in contact with the filter .
The control unit determines an ink feeding amount per unit time by the liquid feeding unit when performing a removing operation of simultaneously discharging bubbles in the ink flow path from the first outlet and the second outlet. In this case, the liquid feeding unit is operated .

The invention according to claim 2
A recording head having a nozzle for ejecting ink and an ink flow path for supplying ink to the nozzle ;
A liquid feeding section that applies pressure to the ink and feeds the ink to the ink flow path; and
A control unit for operating the liquid feeding unit;
With
In the ink flow path, an inflow port through which ink supplied from outside flows in, a filter for filtering the ink that flows in from the inflow port, a communication port to the output flow path that communicates with the nozzle, and the ink flow out An ink chamber having a first outlet and a second outlet to be provided;
The ink chamber by the filter includes the inlet and the first outlet, and includes an upstream ink chamber through which ink that has not passed through the filter flows, the second outlet and the communication port, and the filter And the downstream ink chamber through which the ink that has passed through flows.
The communication port is formed such that an opening area is locally reduced with respect to a cross-sectional area of the output flow path ,
When the controller performs a removing operation for simultaneously discharging bubbles in the ink flow path from the first outlet and the second outlet, ink to the inlet per unit time by the liquid feeding unit Determine the amount of liquid to be supplied and operate the liquid supply part
An ink jet recording apparatus characterized and this.

The invention according to claim 3 is the ink jet recording apparatus according to claim 1 or 2,
The upstream ink chamber is
The inlet and the first outlet are provided along the first long axis when viewed from a direction perpendicular to the filter, extending along a straight first long axis,
In the range where the flow path cross section perpendicular to the ink flow to the first outlet is in contact with the filter, the area of the flow path cross section is formed constant,
The downstream ink chamber is
The second outflow port is provided along the second long axis that extends along a straight second long axis and overlaps the inflow port when viewed from a direction perpendicular to the filter. ,
The area of the cross section of the flow path is formed to be constant within a range in which the cross section of the flow path perpendicular to the ink flow to the second outlet is in contact with the filter.

According to a fourth aspect of the present invention, in the ink jet recording apparatus according to the first aspect,
The channel narrowing member narrows the area of the channel cross section perpendicular to the ink flow to the second outlet by a certain amount along the direction of the flow to the second outlet.

The invention according to claim 5 is the ink jet recording apparatus according to any one of claims 1 to 4,
A first outflow portion for flowing ink flowing out of the first outflow port;
A second outflow portion for flowing ink flowing out from the second outflow port;
With
The first outflow portion is formed such that pressure loss associated with the ink flow is larger than that of the second outflow portion.

According to a sixth aspect of the present invention, in the ink jet recording apparatus of the fifth aspect,
The first outflow portion is provided with an outflow portion constriction member that locally reduces the cross-sectional area of the flow path.

The invention according to claim 7 is the ink jet recording apparatus according to any one of claims 1 to 6,
An ink reservoir for storing ink flowing in from the inlet;
A circulation channel for returning the ink flowing out from the first outlet and the second outlet to the ink reservoir;
It is characterized by having.

The invention according to claim 8 is the ink jet recording apparatus according to any one of claims 1 to 7,
The downstream ink chamber covers the communication port at a position separated from the communication port, and absorbs at least a part of the pressure fluctuation of the ink propagating from the output flow path to the downstream ink chamber. It is characterized by being provided.

The invention according to claim 9 is the ink jet recording apparatus according to any one of claims 1 to 8 ,
A setting storage unit for storing a set value of the ink feeding amount per unit time;
The control unit operates the liquid feeding unit with reference to the set value stored in the setting storage unit when performing the operation of removing bubbles in the ink flow path.

  According to the present invention, there is an effect that in the ink jet recording apparatus, it is possible to easily reduce the amount of wasted ink while reliably removing bubbles.

1 is an overall perspective view illustrating an inkjet recording apparatus according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration relating to ink flow in an inkjet recording apparatus. It is a front view of an inkjet head. It is a figure explaining the ink flow path inside a common ink chamber and a head chip. It is a perspective view which shows the example of the constriction member provided in a 1st discharge part. It is a block diagram which shows the function structure of an inkjet recording device. It is a flowchart which shows the control procedure of the bubble removal process performed with an inkjet recording device. It is a graph which shows the observation result of the bubble omission state in an upper ink chamber and a lower ink chamber. It is a graph which shows the relationship between the flow volume of a liquid feeding pump, and the quantity of the ink leaked from the nozzle.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall perspective view of an inkjet recording apparatus 100 according to an embodiment of the present invention.

  The ink jet recording apparatus 100 is a one-pass apparatus having a plurality of line heads, and includes a transport unit 10, an image forming unit 20, an ink supply unit 30, and the like.

  The transport unit 10 includes a drive roller 11, a transport motor 12, a transport belt 14, and the like. The transport motor 12 rotates the drive roller 11 at a predetermined speed. An endless conveyance belt 14 is wound around the drive roller 11 together with a follower roller (not shown), and the conveyance belt 14 moves around by the rotation of the drive roller 11. A recording medium is placed on the conveying surface with the outer surface of the conveying belt 14 as a conveying surface, and the recording medium is conveyed in the conveying direction as the conveying belt 14 rotates.

  The image forming unit 20 includes a carriage 22 and a carriage lifting / lowering unit 23, and a combination of these carriages 22 and the carriage lifting / lowering unit 23 is provided according to the number of ink colors (eight in this case). . Each of the carriages 22 extends in a direction intersecting with the conveyance direction (x direction) of the recording medium by the conveyance unit 10, in this case, in the orthogonal width direction (y direction). A plurality of inkjet heads 211 (refer to FIG. 2) are fixed in a line head structure so as to be able to eject ink over the entire width of the recording medium that is disposed above (z direction). The plurality of carriages 22 are provided at different positions in the transport direction. The carriage 22 is provided such that the distance from the conveyance surface to the upper side can be changed by the carriage lifting / lowering unit 23, and the distance from the conveyance surface of the inkjet head 211 is also changed as the carriage 22 moves.

The carriage lifting / lowering unit 23 changes the distance from the conveyance surface of the carriage 22. The carriage lift 23 includes a lift motor 232, an electromagnetic brake 233, a beam member 234, a support 235, and the like.
Two beam members 234 are provided substantially in parallel in the direction intersecting the conveyance direction (here, the orthogonal direction, ie, the width direction) on the upper portion of the conveyance belt 14 (on the conveyance surface side of the recording medium). Support portions 235 are fixed to both ends, respectively. A lift motor 232, an electromagnetic brake 233 and a carriage 22 are attached to the support portion 235.
The carriage 22 is moved up and down according to the operations of the lifting motor 232 and the electromagnetic brake 233 that are driven based on a control signal from the control unit 40 (see FIG. 6).

  The lifting motor 232 moves the carriage 22 at a predetermined lifting speed. As the lifting motor 232, for example, a servo motor or a stepping motor is used.

  The electromagnetic brake 233 maintains the fixed state of the carriage 22, and the fixed state is released according to the drive signal, so that the carriage 22 can be temporarily moved by the lifting motor 232. That is, the electromagnetic brake 233 fixes the carriage 22 in a normal state including when the power is turned off. As the electromagnetic brake 233, for example, a disc brake is used.

  The ink supply unit 30 stores ink of each color used for image recording and supplies the ink to the inkjet head 211. Here, each configuration of the ink supply unit 30 is disposed in a dedicated rack 35 or the like, and is connected to the image forming unit 20 via a pipe such as a tube.

Next, the configuration related to the ink flow from the ink supply unit 30 to the image forming unit 20 in the inkjet recording apparatus 100 of the present embodiment will be described.
FIG. 2 is a diagram illustrating a configuration related to the ink flow in the inkjet recording apparatus 100 of the present embodiment.

  The ink supply unit 30 includes a main tank 31, a filter 31a, a supply valve 31b, a supply pump 32, and the like.

  The ink in the main tank 31 is sent to the sub tank 212 of the image forming unit 20 through the filter 31a and the supply valve 31b by the operation of the supply pump 32. The filter 31a removes foreign matters such as dust and dust in the ink, and foreign matters. The supply valve 31 b determines whether ink can be supplied from the main tank 31 to the sub tank 212. The supply valve 31b may be manually switchable when ink is supplied to the main tank 31 or when the main tank 31 is replaced.

  The ink supplied from the main tank 31 to the sub-tank 212 (ink storage unit) of the image forming unit 20 by the supply pump 32 includes a deaeration unit 213, a liquid supply pump 214 (liquid supply unit), a three-way switching valve 214b, The ink is sent to each inkjet head 211 (recording head) through the supply channel 217 and the like. Ink that is not ejected or leaked from each ink-jet head 211 is discharged to the recovery flow path 219 (circulation flow path) via the check valve 219a and returned to the sub tank 212.

  The sub tank 212 is an ink tank having a smaller capacity than the main tank 31. The sub tank 212 is opened to air through an opening valve 212a, and maintains the ink at atmospheric pressure. The sub tank 212 is provided with a liquid level sensor 212b. The liquid level sensor 212b detects the amount of ink in the sub tank 212 and outputs a detection signal to the control unit 40 (see FIG. 6). The liquid level sensor 212b may simply detect whether the ink amount has fallen below a predetermined lower limit reference value and output a detection signal to the control unit 40.

  The deaeration unit 213 removes air in the ink. The deaeration unit 213 includes a deaeration module 213a, a vacuum pump 213b, a pressure sensor 213c, and the like. The degassing module 213a has a structure in which the vacuum flow path reduced by vacuum suction by the vacuum pump 213b and the ink flow path are in contact with each other through the degassing film, and only the air in the ink permeates the degassing film. This removes air from the ink. The pressure sensor 213c is used for abnormality detection such as operation control of the vacuum pump 213b and breakage of the deaeration film.

The liquid feed pump 214 controls the ink degassed by the deaeration unit 213 in the state where the liquid feed valve 214a provided between the liquid feed pump 214 and the deaeration unit 213 is opened (see FIG. 6). The flow rate is set to the negative pressure forming unit 215 or the detour channel 216 at a flow rate (ink feeding amount per unit time). A conventionally known pump can be used as the liquid feed pump 214.
A flow path for returning ink to the sub tank 212 via the relief valve 212c is branched from between the liquid feed pump 214 and the three-way switching valve 214b. When the ink pressure exceeds a specified value, a relief is provided. The valve 212c is opened to release the pressure.

  The three-way switching valve 214 b switches the destination of the ink sent from the liquid feeding pump 214 to either the negative pressure forming unit 215 or the bypass flow path 216 based on the control of the control unit 40. When the destination is switched to the bypass channel 216, the ink is sent directly to the supply channel 217 via the bypass channel 216.

  The negative pressure forming unit 215 keeps the pressure of the ink supplied to the inkjet head 211 lower than the air pressure, thereby preventing the ink from leaking from the nozzles at times other than the timing of ejecting the ink, and the ink from the inkjet head 211. Is supplied to the inkjet head 211 via the protective valve 215a. As the negative pressure forming unit 215, a configuration for generating and maintaining a negative pressure by a conventionally known method can be used. The negative pressure forming unit 215 may include a simple intermediate tank, and may have a similar function by gravity using a height difference from the inkjet head 211.

  From the supply flow path 217, the inflow path connected to the inlet 2114 of each inkjet head 211 is branched via the plurality of operation valves 217a. The supply channel 217 is connected to the recovery channel 219 via a circulation valve 218a.

  The outlet 2117 of each inkjet head 211 is joined to the recovery flow path 219 via a plurality of check valves 219a. The recovery channel 219 is connected to the sub tank 212 via the recovery valve 219 b, and returns undischarged ink that has flowed in from the outlet 2117 and the supply channel 217 to the sub tank 212.

  The ink tray 241 receives these inks and sends them to a waste liquid tank (not shown) when ink is ejected from a nozzle hole of the ink jet head 211 to a place other than the recording medium in a maintenance operation or when the ink leaks. . The ink tray 241 may be provided at a predetermined maintenance position, and the carriage 22 may be movable to a position corresponding to the ink tray 241. Alternatively, the ink tray 241 may be moved to a position facing the nozzle opening. May be.

FIG. 3 is a front view of the inkjet head 211.
The plurality of inkjet heads 211 attached to the carriage 22 are oriented in the front view when viewed from the transport direction (x direction).
In the ink jet head 211, an ink discharge unit 27 is attached to a lower portion of a casing B in which a circuit board of the head drive unit 26 (see FIG. 6) that performs an operation of discharging ink is stored.

The ink discharge unit 27 supplies ink to a nozzle and discharges it as droplets of an appropriate liquid amount from the opening of the nozzle. The nozzle has an opening (nozzle opening) provided on a surface (nozzle surface) facing the conveyance surface of the inkjet head 211, and the ink flies and lands substantially perpendicularly to the recording medium (conveyance surface). It has a configuration. A plurality of nozzle openings are arranged in the width direction at a predetermined interval (pitch) on the nozzle surface of each inkjet head 211. The arrangement pattern of the nozzle openings is not particularly limited, and may be a simple one-dimensional arrangement, or a staggered arrangement having a plurality of rows in the transport direction. A configuration in which the nozzle openings provided in the inkjet head 211 adjacent in the width direction are partially overlapped in the width direction so that ink is reliably discharged over the entire width of the recording medium. It is desirable that
The ink ejection unit 27 includes a common ink chamber 2111 (ink chamber) that distributes the ink supplied to the inkjet head 211 to each nozzle, and a head chip 2112, and the ink supplied to the inkjet head 211 is a common ink chamber. Ink flow paths are provided from 2111 to the individual flow paths 2112b (see FIG. 4, output flow path) in the head chip 2112 to reach each nozzle.

  The common ink chamber 2111 is formed linearly in the width direction (y direction), and is connected to an inlet 2114 into which ink supplied to the inkjet head 211 flows and protrudes upward (z direction). An outlet 2117 for flowing ink discharged from the inkjet head 211 to the recovery flow path 219 includes a first discharge portion 2115 (first outflow portion) and a second discharge portion 2116 (second outflow portion) connected to the common ink chamber 2111. Part) and a connection part 2117a.

  Here, the head chip 2112 has an upper surface (surface opposite to the surface facing the transport surface) joined to the common ink chamber 2111 and a lower surface (surface facing the transport surface) serving as a nozzle surface.

  FIG. 4 is a diagram illustrating the ink flow paths inside the common ink chamber 2111 and the head chip 2112.

  As shown in FIGS. 4A and 4B, the common ink chamber 2111 is a manifold that distributes ink to the individual channels 2112b of the head chip 2112 through a plurality of communication ports 2111c provided on the bottom surface. Make. The inside of the common ink chamber 2111 is divided into upper and lower parts by a filter 2118.

The upper ink chamber 2111a (upstream ink chamber), which is the upper side of the filter 2118, communicates with the tubular inlet 2114 through the inflow port 2111d, and communicates with the tubular first discharge portion 2115 through the first outflow port 2111e. .
The upper ink chamber 2111a has a rectangular parallelepiped shape extending along the first long axis L1 extending in the center of the upper ink chamber 2111a in parallel to the y-axis, and the inflow port 2111d and the first outflow port 2111e have an xy plane. The first major axis L1 overlaps with the first major axis L1, and is provided at a position in the + z direction with respect to the first major axis L1, that is, on the upper surface of the upper ink chamber 2111a. The ink that has flowed from the inlet 2114 through the inlet 2111d into the upper ink chamber 2111a passes through the filter 2118 and flows to the lower ink chamber 2111b (downstream ink chamber) below the filter 2118. It flows along the upper surface, passes through the first outlet 2111e, and can be directly discharged from the first discharge part 2115. The flow of ink from the inflow port 2111d to the first outflow port 2111e is a flow in the −y direction. Therefore, the area of the flow path cross section (flow path cross-sectional area) related to this ink flow is the upper ink chamber 2111a. It is constant within.

  A constriction member 2115a (outflow portion constriction member) is inserted into the first discharge portion 2115. The narrowing member 2115a narrows the flow path diameter of the ink flowing through the first discharge portion 2115 by a certain size (amount), thereby reducing the pressure loss of the ink flowing through the first discharge portion 2115 to the pressure of the ink flowing through the second discharge portion 2116. Increase to a value greater than the loss. Further, the constricting member 2115a flows so that the ratio between the pressure loss due to the constricting member 2115a and the magnitude of the pressure loss received when the ink flowing through the second discharge portion 2116 passes through the filter 2118 becomes an appropriate value. A path diameter (channel cross-sectional area) and a channel length are set. This setting will be described in detail later.

  The lower ink chamber 2111b communicates with the tubular second discharge portion 2116 at the second outlet 2111f. The lower ink chamber 2111b has a rectangular parallelepiped shape extending along the second major axis L2 extending in the center of the lower ink chamber 2111b in parallel with the y-axis. The second major axis L2 overlaps the first major axis L1 in the xy plane, and the length along the second major axis L2 of the lower ink chamber 2111b is longer than the length along the first major axis of the upper ink chamber 2111a. long. Therefore, the inflow port 2111d is at a position overlapping the second long axis L2 on the xy plane. The second outlet 2111f overlaps with the second major axis L2 in the xy plane and is positioned in the + z direction with respect to the second major axis L2, that is, here, on the upper surface of the lower ink chamber 2111b and the upper ink. It is provided at a position not in contact with the chamber 2111a. The ink filtered by the filter 2118 and flowing into the lower ink chamber 2111b from the upper ink chamber 2111a flows into the individual flow path 2112b of the head chip 2112 through the communication port 2111c, and flows along the lower surface of the filter 2118 to the second. It can be discharged from the second discharge part 2116 through the outlet 2111f. The ink flow to the second outlet 2111f is a flow along the −y direction, and therefore the area of the cross-section of the flow path related to the ink flow to the second outlet 2111f is constant in the lower ink chamber 2111b. It has become.

  In addition, a buffer member 2119 (damper) is provided in the lower ink chamber 2111b so as to cover the upper side of the communication port 2111c so as to be separated from the bottom surface (that is, the communication port 2111c), and the ink pressure generated in the individual flow channel 2112b. Absorbing at least a part of the fluctuation and suppressing the propagation of the influence into the other individual flow path 2112b. As the buffer member 2119, a flexible film whose surface can be deformed according to a change in ink pressure is used, and it may be formed in a bag shape in which gas (air) is sealed. Here, the buffer member 2119 is sufficiently thin and / or deformed, and independently reduces the channel cross-sectional area of the lower ink chamber 2111b by a predetermined (fixed) size as the channel narrowing member 2110. Not done. However, when the buffer member 2119 has a thickness, the buffer member 2119 can further enhance the function of the channel narrowing member 2110 described below. In this case, the effect of the buffer member 2119 is considered in setting the size of the flow path constricting member 2110.

  The lower ink chamber 2111b is further provided with a channel narrowing member 2110. This flow path constricting member 2110 is a flow perpendicular to the flow of ink to the second outlet 2111f in the lower ink chamber 2111b as long as it does not adversely affect the passage of the ink through the filter 2118 and the flow into the communication port 2111c. This is for narrowing the area of the road section by a predetermined size as compared with the structure of the conventional inkjet head 211. Therefore, the area of the narrowed channel cross section is constant in the range narrowed by the channel narrowing member 2110. Note that the area of the cross section of the flow path only needs to be narrowed in a range in contact with the filter 2118. Here, the flow path constricting member 2110 extends to both ends of the lower ink chamber 2111b where the cross section of the flow path does not contact the filter 2118. Not. Further, the shape of the flow path constricting member 2110 in the range where the flow path cross section does not contact the filter 2118 is not limited to a planar shape parallel to the flow path cross section, but a shape that tapers at both ends in the direction along the second long axis L2. A shape that does not obstruct the flow of ink is more preferably used.

  The head chip 2112 has individual flow paths 2112b arranged corresponding to the communication ports 2111c of the common ink chamber 2111, respectively. In at least a part of the individual flow path 2112b, it is possible to apply pressure to the ink in a predetermined pattern. Here, at least a part of the wall surface (partition wall) of the individual flow path 2112b is provided so as to be deformable in accordance with the deformation of the piezoelectric element electrically connected to the head driving unit 26, and the individual surface facing the deformable wall surface. The portion of the flow path 2112b forms a pressure chamber that applies a pressure change to the ink. The opening area (channel cross-sectional area) of the communication port 2111c is a narrowed portion that is locally smaller than the channel cross-sectional area near the entrance of the individual channel 2112b. Thereby, when pressure is applied to the ink in the ink chamber 2111 by the liquid feeding operation of the liquid feeding pump 214, the ratio of the ink that flows into the individual flow path 2112b and leaks from the nozzle is reduced. The structure and shape of the individual flow path 2112b can be designed as appropriate.

  A nozzle plate 2112a is bonded to the lower surface of the head chip 2112, that is, the surface facing the transport surface. The nozzle plate 2112a is provided with nozzle holes respectively corresponding to the individual flow paths 2112b, and ink is ejected from the nozzle holes in accordance with the pressure pattern applied to the ink in the pressure chamber.

FIG. 5 is a perspective view showing an example of the constriction member 2115a provided in the first discharge part 2115. FIG.
The constriction member 2115a is a tube-shaped member having a hollow through portion Hh, and a connector or the like may be provided so that the outer periphery thereof is equal to the inner periphery of the tubular first discharge portion 2115. Here, connectors Hc1 and Hc2 are attached to the upper end and lower end of the tube Hp having a predetermined length, and are embedded in the first discharge portion 2115.
Here, a narrow groove Ht is provided on the outer surface of the connector Hc1 on the upper end side (downstream side), and when the constriction member 2115a is inserted and attached to the first discharge portion 2115, the connector Hc1 and Hc2 are connected to each other. The air remaining around the tube Hp can be easily discharged.

Next, the size setting of the flow path constricting member 2110 and the constricting member 2115a will be described.
In the ink jet recording apparatus 100 according to the present embodiment, the ink flow path is configured so that the lower ink chamber 2111b is provided when ink having a predetermined flow rate (ink supply amount per predetermined time) is supplied from the liquid supply pump 214. The flow rate of the ink flowing through the upper ink chamber 2111a and the flow rate of the ink flowing through the lower ink chamber 2111b are formed to be substantially the same while reducing the flow rate of the flowing ink.
The flow velocity here is an average velocity with respect to the flow path cross section of the upper ink chamber 2111a and the lower ink chamber 2111b.

  In the ink jet recording apparatus 100, when the air bubbles remain in the common ink chamber 2111 and are mixed and caught on the filter 2118, the ink jet recording apparatus 100 applies pressure to the air bubbles by the flow of the ink to cause the air bubbles to be detached from the filter 2118. Then, the ink flows out of the common ink chamber 2111 from the first outlet 2111e and the second outlet 2111f. The reference value of the flow rate of ink necessary for removing the bubbles depends on the frictional force according to the material of the filter 2118 and the fineness of the eyes, and the filter 2118 is necessary for the foreign matter to be captured in the ink. It depends on various conditions. Therefore, in the inkjet recording apparatus 100, the flow velocity reference value can be determined as a normal constant value.

  On the other hand, when ink flows through the lower ink chamber 2111b, depending on the ratio of the pressure loss from the communication port 2111c to the nozzle through the individual flow path 2112b and the pressure loss of the second discharge part 2116 and the recovery flow path 219, An amount of ink corresponding to the amount of inflow into the lower ink chamber 2111b, that is, a predetermined ratio of ink flowing between the lower ink chamber 2111b (the ink flow rate in the upper ink chamber 2111a and the ink flow rate in the lower ink chamber 2111b). If the ratio is constant, a certain ratio of ink flowed by the liquid feed pump 214 flows into the individual flow channels 2112b of the head chip 2112 and passes through the nozzle holes of the nozzle plate 2112a to the outside. Leak. Since the leaked ink is wasted (becomes waste), it is preferable that the amount of ink flowing into the lower ink chamber 2111b is kept small. Therefore, in the ink jet recording apparatus 100, the flow path constricting member 2110 is provided in the lower ink chamber 2111b, so that the filter 2118 and the second filter 2118 and the second filter 2118 are within a range in which a decrease in flow rate due to pressure loss in the lower ink chamber 2111b does not matter. The flow rate is reduced while maintaining the flow velocity determined by the pressure loss in the discharge unit 2116 and the ratio of the flow path cross-sectional areas of the upper ink chamber 211a and the lower ink chamber 2111b.

  When the pressure loss corresponding to the cross-sectional area of the lower ink chamber 2111b is sufficiently smaller than the pressure loss in the filter 2118 and the constriction member 2115a, the ratio of the pressure loss due to the filter 2118 and the pressure loss due to the constriction member 2115a is The flow path constriction member 2110 has a flow path cut-off so as to have a value corresponding to the ratio of the flow path cross sectional area of the lower ink chamber 2111b reduced by the flow path narrowing member 2110 and the flow path cross sectional area of the upper ink chamber 2111a. The area and the channel cross-sectional area and length of the constriction member 2115a may be determined and provided in the first discharge portion 2115. When the increase in the pressure loss of the lower ink chamber 2111b reduced by the flow path constricting member 2110 is so large that it cannot be ignored, the constriction member 2115a further causes the pressure loss corresponding to the increase in the pressure loss to occur in the constriction member 2115a. The cross-sectional area and length of the channel are determined.

  Note that the length of the supply channel 217 and the recovery channel 219 is sufficiently longer than the length from the inlet 2114 to the outlet 2117, and the pressure loss of the ink circulating between the sub tank 212 and the inkjet head 211 is large. Since the ratio of the pressure loss in the supply channel 217 and the recovery channel 219 is larger than the pressure loss due to the filter 2118 and the constriction member 2115a, the setting of the channel constriction member 2110 and the constriction member 2115a is changed. However, the ratio of ink leaking from the nozzles is almost unchanged. That is, the amount of ink leakage decreases as the amount of ink flowing in decreases.

Flow rate setting data (setting value) at which the flow rates of the upper ink chamber 2111a and the lower ink chamber 2111b are both equal to or higher than the flow velocity reference value are inspected and set in advance at a factory or the like and stored in the ROM 403 (see FIG. 6).
If changes or changes in ink viscosity that change depending on the type of ink (reactive ink, dispersed ink, or ink color) and ink temperature are assumed, depending on these changes or changes Thus, the pressure loss and its ratio due to the filter 2118 and the constriction member 2115a can change. Accordingly, the flow velocity reference value (flow rate setting data) is not limited to a uniform constant value, but for each ink jet head 211 that is fixed in advance, such as the ink color, the flow rate setting data corresponding to each of the ink jet heads 211 is individually provided. It may be stored in the ROM 403. In the case where a change in the ink type or a change in temperature is expected, even if the pressure loss changes within the expected range of the change or change, the flow rates of the upper ink chamber 2111a and the lower ink chamber 2111b are both the flow rate reference. The constriction member 2115a and the flow path constriction member 2110 are configured with a margin so as to be equal to or greater than the value, and flow rate setting data is determined.

  FIG. 6 is a block diagram illustrating a functional configuration of the inkjet recording apparatus 100 according to the present embodiment.

  As described above, the inkjet recording apparatus 100 includes the transport motor 12, the lift motor 232, the electromagnetic brake 233, the supply valve 31b, the supply pump 32, the liquid level sensor 212b, the vacuum pump 213b, and the pressure sensor 213c. A liquid feed valve 214a, a liquid feed pump 214, a three-way switching valve 214b, a protection valve 215a, a plurality of operation valves 217a, a circulation valve 218a, a recovery valve 219b, and the like. The ink jet recording apparatus 100 includes a control unit 40, a motor driver 231, a head driving unit 26, an operation display unit 16, a communication unit 17, a bus 18, and the like.

  The controller 40 controls the overall operation of the inkjet recording apparatus 100. The control unit 40 includes a CPU 401 (Central Processing Unit), a RAM 402 (Random Access Memory), a ROM 403 (Read Only Memory) as a setting storage unit, a memory 404, and the like.

  The CPU 401 performs various arithmetic processes, and controls the recording medium conveyance, ink ejection, maintenance operations, and the like in the inkjet recording apparatus 100. This maintenance operation includes a bubble removal process for removing bubbles in the ink flow path. Further, the CPU 401 performs various processes related to image recording based on image data, status signals of each unit, clock signals, and the like according to a program read from the ROM 403.

The RAM 402 provides a working memory space to the CPU 401 and stores temporary data.
The ROM 403 stores a control program, initial setting data, and the like. The control program includes a program related to the above-described bubble removal processing, and the initial setting data includes the shape of the inkjet head 211, the type of the filter 2118 in the common ink chamber 2111, the first discharge unit 2115, the second It includes flow rate setting data 403a such as a predetermined ink flow rate (a liquid supply amount per unit time) according to the size and length of the discharge unit 2116 and the narrowing member 2115a, and a liquid supply time at the ink flow rate. The ROM 403 includes a non-volatile memory that can be overwritten and updated, and can store setting data that is maintained and maintained as needed. The memory 404 includes a RAM that temporarily stores image data to be recorded.

The head drive unit 26 generates and outputs a drive voltage signal that causes the pressure chamber (piezoelectric element) to be deformed in order to properly eject ink in the head chip 2112. The head drive unit 26 selects a voltage waveform pattern stored in advance based on a control signal from the control unit 40 and generates a drive voltage signal obtained by power amplification. Each head drive unit 26 generates each drive voltage signal according to image data input from the memory 404. Whether to output a drive voltage signal to the piezoelectric element is switched.
The wiring related to the head driving unit 26 is formed together with the ink flow path in the inkjet head 211, and is formed partially separately.

  The motor driver 231 outputs a drive signal to the electromagnetic brake 233 and the lifting motor 232 according to the control signal from the control unit 40, loosens the electromagnetic brake 233 and operates the lifting motor 232 to move the carriage to a desired position. Or the elevator motor 232 is stopped and the electromagnetic brake 233 is used to fix the carriage.

  The communication unit 17 is a communication interface that controls a communication operation with an external device. As the communication interface, for example, one or a plurality of communication interfaces such as a LAN board and a LAN card corresponding to various communication protocols are included. The communication unit 17 acquires image data to be recorded and setting data (job data) related to image recording from an external device based on the control of the control unit 40, and transmits status information and the like to the external device. I can do it.

  The operation display unit 16 displays a status, an operation menu, and the like of the ink jet recording apparatus 100 according to a control signal from the control unit 40, and receives a user operation and outputs it to the control unit 40. The operation display unit 16 includes, for example, a liquid crystal display unit in which a touch sensor as an operation receiving unit is provided so as to overlap with a display screen as a display unit. The control unit 40 displays various menus for accepting commands by the status and touch sensor on the liquid crystal display unit, and displays information on the contents and position of the displayed menu and the user's touch operation detected by the touch sensor. A control operation is performed to cause each unit of the inkjet recording apparatus 100 to perform a corresponding process.

  The bus 18 is a path for exchanging signals by electrically connecting the above components.

  In addition to these configurations, the ink jet recording apparatus 100 detects a notification operation unit such as an LED lamp and / or a beep generation unit used for a notification operation, and an image quality abnormality (defect) of an image formed on a recording medium. For example, a reading unit such as a line sensor or a mounting abnormality detection sensor that detects that the supplied recording medium is not normally mounted on the conveyance surface may be provided.

  Next, the bubble removal operation in the inkjet recording apparatus 100 of the present embodiment will be described.

  In the ink jet recording apparatus 100 of the present embodiment, when ink is initially introduced, when ink is once removed from the ink flow path during a maintenance operation or when the ink type is changed, bubbles are mixed in the ink flow path. In such a case, the ink is allowed to flow into the common ink chamber 2111 of the recording head at the above-described flow velocity reference value or at a slightly higher flow velocity (for example, 1.2 times the flow velocity reference value). The air bubbles caught inside the filter 2118 are removed with the flow of the ink.

  As described above, in the three-way switching valve 214b, during normal recording operation, the ink is switched to be sent to the negative pressure forming unit 215, and the ink is transferred from the negative pressure forming unit 215 to the inkjet head 211 as needed according to the ejected ink. In contrast, during the bubble removal operation (maintenance operation), the ink is switched to be sent to the bypass flow path 216, and the liquid is fed by the liquid feed pump 214 at a predetermined flow rate. As a result, ink flows through the upper ink chamber 2111a and the lower ink chamber 2111b at a substantially constant speed and is discharged from the first discharge portion 2115 and the second discharge portion 2116.

FIG. 7 is a flowchart showing a control procedure by the control unit 40 of the bubble removal process executed in the inkjet recording apparatus 100.
This bubble removal process is a maintenance operation when it is manually activated by a user operation, when the inkjet recording apparatus 100 is turned on, when an abnormal image quality is detected during the image recording operation, or the like. Is called from the ROM 403 by the CPU 401 and executed.

  When the bubble removal process is started, the control unit 40 (CPU 401) relatively moves the nozzle surface and the ink tray 241 to face each other (step S101). The control unit 40 closes the protection valve 215a and the circulation valve 218a, opens the operation valve 217a and the recovery valve 219b corresponding to (all in this case) the inkjet head 211 that is the target of bubble removal, and opens the three-way switching valve 214b. The detour channel 216 is set (step S102).

  The control unit 40 acquires the setting relating to the flow rate corresponding to the reference flow rate necessary for the bubble removal from the flow rate setting data 403a of the ROM 403 (step S103). The control unit 40 operates the liquid feed pump 214 to cause each ink jet head 211 to feed ink at a flow rate acquired as an amount necessary for removing bubbles (step S104). The control unit 40 counts the operation time of the liquid feed pump 214 and stops the operation of the liquid feed pump 214 after a preset liquid feed time has elapsed (step S105). Then, the control unit 40 closes the collection valve 219b (Step S106). Other valves are opened and closed according to the subsequent operation. Then, the control unit 40 ends the bubble removal process.

[Example]
An ink jet head was produced in which a communication port was provided on the lower surface of the common ink chamber, and a head chip provided with an individual flow path corresponding to the communication port was joined.
A filter is provided horizontally in the center in the height direction of the common ink chamber, the flow path cross section of the rectangular parallelepiped upper ink chamber is 36 mm ^2, and the flow path cross section of the rectangular parallelepiped lower ink chamber is 28 mm ² . Cylindrical inflow passages and discharge passages with a diameter of 2.8 mm are provided at both ends of the upper surface of the upper ink chamber, and discharge passages of the same size are provided at the upper surface of the end portion opposite to the inflow passage in the lower ink chamber It was. A narrowing member having a length of 14 mm having a cylindrical hollow structure with a diameter of 0.9 mm was further inserted into the discharge path provided in the upper ink chamber. The discharge path provided in the upper ink chamber and the discharge path provided in the lower ink chamber were merged and returned to the ink tank (sub tank) via a 6 m recovery path.

  In this ink jet head, a liquid feed pump for supplying ink from the ink tank to the inflow path was attached, and the bubble deflation in the upper ink chamber and the lower ink chamber was visually observed while changing the flow rate.

FIG. 8 is a chart showing the observation results of how bubbles are removed in the upper ink chamber and the lower ink chamber.
Here, a Y-color reactive ink (25 ° C.) having a specific gravity of 1.12 and a viscosity of 4.2 cp ± 0.3 was introduced.

In the upper ink chamber, bubbles did not escape when the flow rate was 1.25 cm / sec (×), and bubbles did not escape even when the flow rate was 1.67 cm / sec (Δ). On the other hand, when the flow rate was 2.31 cm / sec or more, the bubbles were completely removed (◯).
In the lower ink chamber, when the flow rate was 1.61 cm / sec, the bubbles were not completely removed (Δ), and when the flow rate was 2.14 cm / sec or more, the bubbles were completely removed (◯).

  Thus, a result was obtained that there was a correlation between the degree of bubble removal and the flow rate of ink flowing through each ink chamber. Similar results were confirmed for each value in the viscosity range of 3.5 to 10.8 cp and the specific gravity range of 1.05 to 1.20.

  In addition, in the prepared ink jet head, a liquid feed pump was attached to the upper end portion of the inflow path, and the relationship between the flow rate (the amount of ink supplied to the ink jet head per unit time) and the amount of ink leaking from the nozzle was examined. .

FIG. 9 is a graph showing the relationship between the flow rate of the liquid feed pump and the amount of ink leaked from the nozzles.
Here, the case of using 20 ° C. dispersed ink (black circle) and the case of using 23 ° C. reactive ink (circle) are shown in an overlapping manner.

  There is a clear correlation (correlation coefficient is 0.8947) between the flow rate of the liquid feed pump and the amount of ink leaked from the nozzle hole (waste liquid amount), and about 1/3 of the liquid feed amount leaks. The result of doing was obtained. Moreover, in this result, the result that there was no difference by the kind and viscosity of an ink was obtained.

As described above, the ink jet recording apparatus 100 according to the present embodiment includes the ink jet head 211 having the nozzle for ejecting ink and the ink flow path for supplying ink to the nozzle. Inflow port 2111d into which the supplied ink flows in, filter 2118 for filtering the ink flowing in from the inflow port 2111d, communication port 2111c to the individual flow path 2112b communicating with the nozzle, and first outflow port from which the ink flows out 2111e and a second outlet 2111f are provided, and the common ink chamber 2111 includes an inlet 2111d and a first outlet 2111e by a filter 2118, and does not pass through the filter 2118. The upper ink chamber 2111a through which the water flows and the second outlet 2111 And a lower ink chamber 2111b that includes the communication port 2112c and through which the ink that has passed through the filter 2118 flows. The lower ink chamber 2111b has a flow perpendicular to the ink flow to the second outlet 2111f. A flow path narrowing member 2110 that narrows the area of the path cross section is provided.
With such a configuration, when ink is supplied from the inflow port 2111d at a predetermined ink supply amount per unit time with the recovery valve 219b opened, the flow rate of ink flowing through the filter 2118 to the lower ink chamber 2111b. The flow rate can be increased while suppressing Accordingly, it is possible to more easily and surely remove bubbles that have flowed into the lower ink chamber 2111b with the flow velocity while suppressing the amount of wasted ink discharged from the nozzles according to the flow rate. In particular, even if air bubbles caught on the filter 2118 that forms the upper surface of the lower ink chamber 2111b are taken into consideration with the friction with the surface of the filter 2118, the flow velocity narrows immediately near the filter 2118 because the flow path becomes narrower. This makes it easy to produce a flow velocity with respect to the bubbles, so that the bubbles can be effectively removed.

  In the ink jet recording apparatus 100 of the present embodiment, the communication port 2111c is formed so that the opening area is locally smaller than the cross-sectional area of the individual flow path 2112b. As a result, when pressure is applied by the liquid feed pump 214 and liquid is fed to the lower ink chamber 2111b, it leaks from the nozzle through the communication port 2111c as compared with the amount of ink flowing through the lower ink chamber 2111b. The amount of ink can be reduced. Accordingly, it is possible to easily and reliably remove the bubbles in the lower ink chamber 2111b while suppressing the amount of wasted ink discharged from the nozzles.

The upper ink chamber 2111a extends in the y direction along the linear first long axis L1, and flows along the first long axis L1 when viewed from the z direction perpendicular to the filter 2118. An inlet 2111d and a first outlet 2111e are provided, and the flow path cross section in the xz plane perpendicular to the ink flow in the −y direction to the first outlet 2111e is within a range in contact with the filter 2118. The lower ink chamber 2111b extends in the y direction along the linear second major axis L2 and is viewed from the z direction perpendicular to the filter 2118. In this case, a second outlet 2111f is provided along the second long axis L2 that overlaps the inlet 2111d, and is in the xz plane perpendicular to the ink flow in the −y direction to the second outlet 2111f. The channel cross section of To the extent that contact with Luther 2118, the area of the passage cross section is formed in a certain rectangular.
This reduces the pressure loss that the ink receives in the upper ink chamber 2111a and the lower ink chamber 2111b, and the occurrence of stagnation and turbulence in the flow, and in particular, the flow of the necessary flow velocity is easily generated in the range in contact with the filter 2118. Thus, bubbles in the upper ink chamber 2111a and the lower ink chamber 2111b can be removed by flowing.

  Further, the flow path narrowing member 2110 narrows the area of the flow path cross section perpendicular to the ink flow in the −y direction to the second outlet 2111f by a certain amount along the flow direction in the −y direction. It is a rectangular parallelepiped shape. Therefore, the flow path constricting member 2110 does not cause an unnecessarily large pressure loss, flow stagnation or turbulence, and restricts the ink flow rate to suppress wasteful ink leakage from the nozzles, while preventing the upper ink chamber 2111a and Air bubbles in the lower ink chamber 2111b can be more reliably removed.

  The first discharge portion 2115 for flowing the ink flowing out from the first outlet 2111e and the second discharge portion 2116 for flowing the ink flowing out of the second outlet 2111f are provided. The first discharge portion 2115 includes the second discharge portion 2115. The pressure loss associated with the ink flow is larger than that of the discharge unit 2116. As a result, the ink flowing through the upper ink chamber 2111a receives a pressure loss instead of the pressure loss that the ink flowing through the lower ink chamber 2111b receives when passing through the filter 2118. The ink that has flowed in is appropriately supplied not only to the upper ink chamber 2111a but also to the lower ink chamber 2111b according to the ratio of the pressure loss. Accordingly, since the amount of ink flowing to the upper ink chamber 2111a can be reduced in order to obtain a required flow rate in the lower ink chamber 2111b, the amount of liquid fed per hour as a whole can also be reduced. This also eliminates the need to increase the capacity of the liquid feed pump 214 more than necessary.

  Further, the first discharge part 2115 is provided with a constriction member 2115a for locally reducing the flow path cross-sectional area. As described above, since the operation related to the removal of the bubbles in the flow path can be improved by simply inserting the narrowing member 2115a into the configuration of the conventional ink jet recording apparatus 100, an increase in cost due to the improvement can be avoided. I can do it.

  In addition, a subtank 212 that stores ink that flows in from the inflow port 2111d, and a recovery flow path 219 that returns ink that flows out of the first outflow port 2111e and the second outflow port 2111f to the subtank 212 are provided. That is, since the ink other than the ink leaked from the nozzle can be easily returned to the sub tank 212 and used again, the amount of ink leaked from the nozzle can be reduced to reduce the waste of ink.

Further, the lower ink chamber 2111b covers the communication port 211c at a position separated from the communication port 211c, and absorbs at least a part of the pressure fluctuation of the ink propagating from the individual flow channel 2112b to the lower ink chamber 2111b. A member 2119 is provided.
Thus, the buffer member 2119 appropriately discharges ink without affecting the influence of the ink discharge operation of each individual flow path 2112b on the other individual flow paths at the time of ink discharge, and the flow path constricting member 2110 by the buffer member 2119. It is possible to further strengthen the stenosis of the channel.

  In addition, a liquid feed pump 214 that applies pressure to the ink and sends the ink to the ink flow path, and an ink per unit time by the liquid feed pump 214 when the operation of removing bubbles in the ink flow path is performed. And a control unit 40 (CPU 401) for operating the liquid feed pump 214 by determining the liquid feed amount. Accordingly, the bubbles in the ink flow path can be removed from both the upper and lower sides of the filter 2118 more reliably than in the conventional case by a simple one-time control operation.

  In addition, a ROM 403 that stores the set value of the ink feeding amount per unit time as the flow rate setting data 403a is provided, and the control unit 40 (CPU 401) stores in the ROM 403 when performing the operation of removing bubbles in the ink flow path. The liquid feed pump 214 is operated with reference to the set value. Accordingly, it is possible to easily determine an optimal ink feeding amount that can effectively remove bubbles without wasting ink, and to cause the ink to flow into the ink flow path to remove the bubbles.

The present invention is not limited to the above-described embodiment, and various modifications can be made.
For example, in the above embodiment, the filter 2118 divides the common ink chamber 2111 into upper and lower ink chambers 2111a and 2111b, but it may be divided in the left-right direction. Further, the flow path cross-sectional areas of the upper ink chamber 2111a and the lower ink chamber 2111b are not necessarily constant. Further, the upper ink chamber 2111a and the lower ink chamber 2111b may have different shapes as well as sizes. What is necessary is just to determine so that the speed | rate required for bubble removal may come out in the widest part (part where a flow velocity falls) in the range which is in contact with the filter 2118. In addition, the common ink chamber 2111 may be curved in a range where it does not contact the filter 2118, and some or all of the inflow port 2111d, the first outflow port 2111e, and the second outflow port 2111f are respectively the upper ink chamber 2111a, It may be provided other than the upper surface of the lower ink chamber 2111b.

  Further, as described above, the buffer member 2119 is not included in the one that narrows the flow path cross-sectional area by a predetermined size. However, by forming the support member of the buffer member 2119 larger than the size necessary for support, the flow path constriction member It is also possible to form it integrally with 2110.

  Moreover, in the said embodiment, although the constriction member 2115a was provided in the 1st discharge part 2115, the 1st discharge part 2115 itself may be a structure narrow locally. Alternatively, by making the first discharge part 2115 longer than the second discharge part 2116 or bending the first discharge part 2115, the pressure loss of the first discharge part 2115 is made larger than the pressure loss of the second discharge part 2116. May be increased. Further, a suction pump that sucks ink from the lower ink chamber 2111b and flows it to the outlet 2117 is provided in the second discharge portion 2116, thereby making the effective pressure loss in the second discharge portion 2116 a negative value. You may make it smaller than the pressure loss of 2115.

  In addition, the configuration of the ink flow path before and after the ink jet head 211 shown in the above embodiment is the supply of a predetermined ink flow rate for ink discharge related to normal image recording from the ink jet head 211 and for maintenance such as bubble removal. Any configuration that can supply ink that is sometimes required can be appropriately changed.

  In the above embodiment, the individual flow path 2112b is expressed in a simple rectangular parallelepiped shape. However, the structure of the individual flow path 2112b depends on the manufacturing method of the head chip 2112, the shape of the pressure chamber, the method of applying pressure, and the like. May be appropriately bent or the channel cross-sectional area may be locally changed. Further, when there is no need according to such a structure, the buffer member 2119 is not necessarily provided.

  Further, in the above embodiment, the ink that has flowed out of the first discharge unit 2115 and the second discharge unit 2116 is returned to the sub tank 212 by the recovery flow path 219. However, the ink and the administrator are once stored in the waste liquid tank. May be manually collected and recycled.

Further, the number of nozzles and the like can be set as appropriate, and the size and the like of the narrowing member 2115a and the flow path narrowing member 2110 can be appropriately changed according to the number of nozzles.
In addition, specific details such as configurations and settings shown in the above embodiments can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Conveyance part 11 Drive roller 12 Conveyance motor 14 Conveyance belt 16 Operation display part 17 Communication part 18 Bus | bath 20 Image formation part 211 Inkjet head 2110 Flow path constriction member 2111 Common ink chamber 2111a Upper ink chamber 2111b Lower ink chamber 2111c Communication port 2111d Flow Inlet 2111e First outlet 2111f Second outlet 2112 Head chip 2112a Nozzle plate 2112b Individual flow path 2114 Inlet 2115 First outlet 2115a Narrow member 2116 Second outlet 2117 Outlet 2117a Connecting part 2118 Filter 2119 Buffer member 212 Sub tank 212a Open Valve 212b Liquid level sensor 212c Relief valve 213 Deaeration unit 213a Deaeration module 213b Vacuum pump 213c Pressure sensor 214 Liquid feed pump 214a Liquid feed valve 214b Three-way switching valve 215 Negative pressure forming part 215a Protection valve 216 Detour flow path 217 Supply flow path 217a Operation valve 218a Circulation valve 219 Recovery flow path 219a Check valve 219b Recovery valve 22 Carriage 23 Carriage lift 231 Motor driver 232 Lifting motor 233 Electromagnetic brake 234 Beam member 235 Support unit 241 Ink tray 26 Head drive unit 27 Ink discharge unit 30 Ink supply unit 31 Main tank 31a Filter 31b Supply valve 32 Supply pump 35 Rack 40 Control unit 401 CPU
402 RAM
403 ROM
403a Flow rate setting data 404 Memory 100 Inkjet recording apparatus B Housing Hc1 Connector Hh Through hole Hp Tube Ht Narrow groove

Claims (9)

A recording head having a nozzle for ejecting ink and an ink flow path for supplying ink to the nozzle ;
A liquid feeding section that applies pressure to the ink and feeds the ink to the ink flow path; and
A control unit for operating the liquid feeding unit ;
With
In the ink flow path, an inflow port through which ink supplied from outside flows in, a filter for filtering the ink that flows in from the inflow port, a communication port to the output flow path that communicates with the nozzle, and the ink flow out An ink chamber having a first outlet and a second outlet to be provided;
The ink chamber includes the inlet and the first outlet by the filter, and includes an upstream ink chamber through which ink not passing through the filter flows, the second outlet and the communication port, It is divided into a downstream ink chamber through which the ink that has passed through the filter flows,
The downstream ink chamber is provided with a channel narrowing member that narrows the area of the channel cross section perpendicular to the ink flow to the second outlet in a range in contact with the filter .
The control unit determines an ink feeding amount per unit time by the liquid feeding unit when performing a removing operation of simultaneously discharging bubbles in the ink flow path from the first outlet and the second outlet. An ink jet recording apparatus that operates the liquid feeding unit . A recording head having a nozzle for ejecting ink and an ink flow path for supplying ink to the nozzle ;
A liquid feeding section that applies pressure to the ink and feeds the ink to the ink flow path; and
A control unit for operating the liquid feeding unit ;
With
In the ink flow path, an inflow port through which ink supplied from outside flows in, a filter for filtering the ink that flows in from the inflow port, a communication port to the output flow path that communicates with the nozzle, and the ink flow out An ink chamber having a first outlet and a second outlet to be provided;
The ink chamber by the filter includes the inlet and the first outlet, and includes an upstream ink chamber through which ink that has not passed through the filter flows, the second outlet and the communication port, and the filter And the downstream ink chamber through which the ink that has passed through flows.
The communication port is formed such that an opening area is locally reduced with respect to a cross-sectional area of the output flow path ,
When the controller performs a removing operation for simultaneously discharging bubbles in the ink flow path from the first outlet and the second outlet, ink to the inlet per unit time by the liquid feeding unit Determine the amount of liquid to be supplied and operate the liquid supply part
Jet recording apparatus characterized and this. The upstream ink chamber is
The inlet and the first outlet are provided along the first long axis when viewed from a direction perpendicular to the filter, extending along a straight first long axis,
In the range where the flow path cross section perpendicular to the ink flow to the first outlet is in contact with the filter, the area of the flow path cross section is formed constant,
The downstream ink chamber is
The second outflow port is provided along the second long axis that extends along a straight second long axis and overlaps the inflow port when viewed from a direction perpendicular to the filter. ,
The area of the cross section of the flow path is formed to be constant within a range in which a cross section of the flow path perpendicular to the flow of ink to the second outlet is in contact with the filter. Inkjet recording apparatus.   The flow path narrowing member narrows the area of the flow path cross section perpendicular to the ink flow to the second outlet by a certain amount along the direction of the flow to the second outlet. Item 2. An ink jet recording apparatus according to Item 1. A first outflow portion for flowing ink flowing out of the first outflow port;
A second outflow portion for flowing ink flowing out from the second outflow port;
With
5. The inkjet recording according to claim 1, wherein the first outflow portion is formed such that pressure loss associated with the ink flow is larger than that of the second outflow portion. apparatus.   6. The ink jet recording apparatus according to claim 5, wherein the first outflow portion is provided with an outflow portion constricting member that locally reduces the flow path cross-sectional area. An ink reservoir for storing ink flowing in from the inlet;
A circulation channel for returning the ink flowing out from the first outlet and the second outlet to the ink reservoir;
An ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is provided.   The downstream ink chamber covers the communication port at a position separated from the communication port, and absorbs at least a part of the pressure fluctuation of the ink propagating from the output flow path to the downstream ink chamber. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is provided. A setting storage unit for storing a set value of the ink feeding amount per unit time;
Wherein, when performing the removing operation of bubbles in the ink flow path, according to claim 1, by referring to the setting value stored in the setting storage unit, characterized in that operating the liquid feed portion The inkjet recording apparatus as described in any one of -8 .

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