JP6134624B2 - Liquid ejecting unit and liquid ejecting apparatus - Google Patents

Description

  The present invention relates to a liquid ejecting unit that ejects and records droplets on a recording medium, and more particularly to a liquid circulation type liquid ejecting unit and a liquid ejecting apparatus using the same.

  In recent years, an ink jet type liquid ejecting head has been used in which ink droplets are ejected onto recording paper or the like to record characters and figures, or a liquid material is ejected onto the surface of an element substrate to form a functional thin film. In this method, a liquid such as ink or a liquid material is guided from a liquid tank to a channel via a supply pipe, pressure is applied to the liquid filled in the channel, and the liquid is discharged from a nozzle communicating with the channel. When discharging the liquid, the liquid ejecting head or the recording medium is moved to record characters and figures, or a functional thin film having a predetermined shape is formed.

  In this type of liquid ejecting apparatus, a type in which the liquid supplied to the liquid ejecting head is circulated is widespread. Circulating the liquid prevents dust and bubbles from staying in the liquid ejecting head and prevents defective discharge, and can always supply fresh liquid to the liquid ejecting head. Can be prevented.

  Patent Document 1 describes a circulation system in which ink circulates between a recording head unit and an ink tank. An outward ink tube and a return ink tube are installed between the liquid tank and the recording head unit. A pump is installed on the ink tank side of the forward ink tube to pump the ink in the ink tank to the recording head unit and circulate the ink between the ink tank and the recording head unit. With this configuration, bubbles and thickened ink remaining in the tube and the recording head unit are collected in the ink tank and removed.

JP-A-5-330073

  In the circulation system described in Patent Document 1, ink is fed from a pump installed near the ink tank to the recording head unit via the forward ink tube, and from the recording head unit to the ink tank via the backward ink tube. Ink is collected. For this reason, it is necessary to connect the ink tube of the forward path and the backward path to the ink tank, and it takes time to assemble. In addition, when the forward and backward ink tubes are lengthened, the pressure loss in the ink tubes increases, and when the recording head unit moves, pressure fluctuations occur due to the inertia of the ink in the ink tubes. It becomes difficult to control.

  The liquid ejecting unit of the present invention is connected to a circulation unit including two liquid chambers, a supply path for supplying liquid, a communication flow path that connects the two liquid chambers, and two liquid chambers. A head portion having two connection ports and an internal flow path communicating the two connection ports, and the circulation unit has a volume increase amount of one liquid chamber and a volume of the other liquid chamber. The amount of decrease was assumed to be equal.

  Further, the supply path is connected to a flow path point of the communication flow path where the flow path resistance to each liquid chamber is equal.

  Further, the pressure loss of the liquid flowing into the head portion from the supply path via one liquid chamber, and the pressure loss of the liquid flowing from the supply path to the head portion via the other liquid chamber Are equal.

  In the circulation unit, a part or all of the side walls constituting each liquid chamber is made of a movable wall.

  Further, the movable wall is formed of a side wall common to the two liquid chambers.

  Further, the movable wall includes side walls common to the two liquid chambers and side walls not common to the two liquid chambers.

  The side wall common to the two liquid chambers is made of a flexible film.

  Further, the movable wall is composed of two side walls not common to the liquid chambers.

  The two side walls forming the movable walls of the two liquid chambers are connected by a connecting member.

  Further, the side wall forming the movable wall not common to the two liquid chambers has a bellows structure.

  The movable wall is reciprocated.

  In addition, a pump for feeding liquid to the communication flow path and a liquid tank for supplying liquid to the pump are provided.

  According to another aspect of the invention, a liquid ejecting apparatus includes any one of the liquid ejecting units described above, a moving mechanism that relatively moves the liquid ejecting unit and the recording medium, and a liquid tank that supplies liquid to the supply path. It was decided.

  The liquid ejection unit according to the present invention is connected to a circulation unit including two liquid chambers, a supply path to which liquid is supplied, and communicates with the two liquid chambers, and 2 communicates with each of the two liquid chambers. And a head portion having an internal flow path communicating with the two connection ports. Thereby, the liquid of a head part can be circulated by a simple structure, without accompanying a complicated control system.

It is a schematic diagram of the liquid ejecting unit according to the first embodiment of the present invention. The relationship of the moving speed of the movable wall in the liquid injection unit of this invention and the pressure of the liquid of a 1st and 2nd liquid chamber and a nozzle surface is represented. FIG. 6 is a schematic diagram of a liquid ejecting unit according to a second embodiment of the present invention. FIG. 6 is a schematic diagram of a liquid ejecting unit according to a third embodiment of the present invention. It is a schematic diagram of the liquid injection unit which concerns on 4th embodiment of this invention. FIG. 10 is a schematic perspective view of a liquid ejecting apparatus according to a fifth embodiment of the invention.

(First embodiment)
FIG. 1 is a schematic diagram of a liquid ejecting unit 1 according to the first embodiment of the present invention. The basic configuration of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the liquid ejecting unit 1 includes a circulation unit 2 including two liquid chambers, a first liquid chamber 8a and a second liquid chamber 8b, and a supply path 5 for liquid supply, which are connected to each other. The communication channel 4 communicating with the first and second liquid chambers 8a and 8b, the two connection ports 7a and 7b communicating with the two first and second liquid chambers 8a and 8b, respectively, and the two connection ports 7a and 7b And a head portion 6 having an internal flow path 7c communicating with each other. Here, in the circulation unit 2, the volume increase amount of one first liquid chamber 8a (or second liquid chamber 8b) is equal to the volume decrease amount of the other second liquid chamber 8b (or first liquid chamber 8a). .

  This will be specifically described. The wall that partitions the first liquid chamber 8a and the second liquid chamber 8b is a side wall that is common to the first liquid chamber 8a and the second liquid chamber 8b, and includes the movable wall 3. When the movable wall 3 moves to the right, the liquid is sent from the second liquid chamber 8b to the first liquid chamber 8a via the internal flow path 7c and the communication flow path 4, and when the movable wall 3 moves to the left, The liquid is sent from the one liquid chamber 8 a to the second liquid chamber 8 b through the internal flow path 7 c and the communication flow path 4, and the liquid circulates through the head portion 6. That is, the movable wall 3 is reciprocated by a driving unit (not shown) to circulate the liquid in the internal flow path 7 c of the head unit 6. The movable wall 3 may be a piston-like plate body that moves left and right without being deformed, or may be a flexible film that moves while the outer periphery is fixed and the central portion expands left and right.

  Since the movable wall 3 is a side wall common to the first liquid chamber 8a and the second liquid chamber 8b, the volume change amount (for example, the volume increase amount) of the first liquid chamber 8a and the volume change amount of the second liquid chamber 8b ( For example, the volume reduction amount is equal. Further, the pressure loss of the liquid flowing into the head portion 6 from the supply path 5 via the first liquid chamber 8a and the pressure loss of the liquid flowing into the head portion 6 from the supply path 5 via the second liquid chamber 8b. And are equal. Therefore, the supply path 5 is connected to the flow path point X of the communication flow path 4 where the flow path resistances to the first and second liquid chambers 8a and 8b are equal. Further, the flow path resistance from the first liquid chamber 8a to the head part 6 and the flow path resistance from the second liquid chamber 8b to the head part 6 are configured to be equal.

  The pressure of the liquid in the first liquid chamber 8a (static pressure) when the movable wall 3 is moved to send the liquid from the first liquid chamber 8a to the second liquid chamber 8b or from the second liquid chamber 8b to the first liquid chamber 8a. , The same applies hereinafter)), P2 is the pressure of the liquid in the second liquid chamber 8b, and P2 is the pressure of the liquid on the nozzle surface N communicating with the flow path point X and the internal flow path 7c, ignoring the water head difference based on the potential energy. Px is Px = (P1 + P2) / 2. The amount of change in the pressure of the liquid in the first liquid chamber 8a and the amount of change in the pressure in the second liquid chamber 8b accompanying the movement of the movable wall 3 are equal in absolute value and are canceled out in the above equation. That is, the liquid pressure does not fluctuate at the flow path point X or the internal flow path 7c even when the movable wall 3 moves. Therefore, the movement of the movable wall 3 contributes only to the circulation of the liquid, and is not affected by the movement of the movable wall 3 when the droplet is ejected from the head unit 6. When the liquid droplets are discharged from the nozzle 9 and the liquid in the internal flow path 7 c is consumed, the pressure in the internal flow path 7 c decreases and the liquid is replenished from the supply path 5.

  FIG. 2 shows the relationship between the moving speed of the movable wall 3 and the pressure of the liquid in the first and second liquid chambers 8a and 8b and the nozzle surface N in the liquid ejecting unit 1 of the present invention. The horizontal axis represents the moving speed of the movable wall 3, and the vertical axis represents the liquid pressure. Graph G1 represents a change in pressure P1 in the first liquid chamber 8a, graph G2 represents a change in pressure P2 in the second liquid chamber 8b, and graph Gx represents a change in liquid pressure Px in the nozzle surface N. When the moving speed of the movable wall 3 increases, the absolute value of the pressure in the first liquid chamber 8a and the second liquid chamber 8b gradually increases, but the graph Gx indicating the pressure of the liquid on the nozzle surface N shows the moving speed of the movable wall 3. A constant pressure of −1 kPa is shown without being affected. That is, even if the moving speed of the movable wall 3 changes, the liquid meniscus formed on the nozzle surface N is not affected. Similarly, since the pressure of the liquid at the flow path point X is not affected by the moving speed of the movable wall 3, the liquid is drawn from the supply path 5 according to the movement of the movable wall 3, or the liquid is caused to flow backward into the supply path 5. There is nothing. In practice, there is a water head difference between the liquid pressure at the flow path point X and the liquid pressure at the nozzle surface N in accordance with the difference in potential energy. When the liquid droplets are discharged from the nozzle 9 and the internal flow path 7 c is depressurized, this water head difference is maintained, the flow path point X is also depressurized, and the liquid is replenished from the supply path 5.

  In this way, the liquid in the head unit 6 can be circulated with a simple configuration without using a complicated control system. The circulation unit 2 can be stopped and used at the time of recording by the head unit 6 and can be used for maintenance. For example, the movable wall 3 is stopped during the recording operation of the head unit 6, the liquid is supplied to the head unit 6 via the first liquid chamber 8a and the second liquid chamber 8b, and the operating wall 3 is moved during maintenance. The liquid is circulated through the head unit 6 to restore nozzle omission and the like. Further, if the communication flow path 4 and the circulation unit 2 are configured integrally with the head unit 6, it is only necessary to connect a single liquid supply tube from the liquid tank to the liquid ejection unit 1. The liquid ejecting unit 1 having the property can be configured.

(Second embodiment)
FIG. 3 is a schematic diagram of the liquid ejecting unit 1 according to the second embodiment of the present invention. A different point from 1st embodiment is the structure of the circulation unit 2, and others are the same as that of 1st embodiment. The same portions or portions having the same function are denoted by the same reference numerals.

  As shown in FIG. 3, the liquid ejecting unit 1 includes a circulation unit 2 including two liquid chambers 8, a first liquid chamber 8 a and a second liquid chamber 8 b, and a supply path 5 for supplying liquid, A communication flow path 4 that connects the liquid chamber 8a and the second liquid chamber 8b, two connection ports 7a and 7b that communicate with the two first and second liquid chambers 8a and 8b, and two connection ports 7a and 7b, respectively. And a head portion 6 having an internal flow path 7c communicating with each other. In the circulation unit 2, the volume increase amount of the first liquid chamber 8a (or the second liquid chamber 8b) is equal to the volume decrease amount of the second liquid chamber 8b (or the first liquid chamber 8a).

  This will be specifically described. The first liquid chamber 8 a is surrounded by the outer wall 12 a, the side wall of the bellows structure, and the common wall 11. Similarly, the second liquid chamber 8 b is surrounded by the outer wall 12 b, the side wall of the bellows structure, and the common wall 11. The first liquid chamber 8a and the second liquid chamber 8b have the same inner diameter of the side wall of the bellows structure. The common wall 11 constitutes a common side wall of the first liquid chamber 8a and the second liquid chamber 8b. The outer wall 12a of the first liquid chamber 8a and the outer wall 12b of the second liquid chamber 8b are fixed to the outer frame 10. When the common wall 11 is moved relative to the right with respect to the outer frame 10, the liquid is sent out from the second liquid chamber 8 b to the first liquid chamber 8 a via the internal flow path 7 c and the communication flow path 4. When the wall 11 is moved relative to the left with respect to the outer frame 10, the liquid is sent from the first liquid chamber 8a to the second liquid chamber 8b through the internal flow path 7c and the communication flow path 4, and the head portion 6 circulates liquid. Accordingly, the liquid circulates through the head portion 6 by the reciprocating motion of the movable wall. Here, the movable wall includes a side wall common to the two liquid chambers 8 and a side wall not common to the two liquid chambers 8. Specifically, the movable wall includes a side wall composed of a common wall 11 common to the first liquid chamber 8a and the second liquid chamber 8b, and a side wall of a bellows structure not common to the first liquid chamber 8a and the second liquid chamber 8b. including.

  At this time, in the circulation unit 2, the volume increase amount (or volume decrease amount) of the first liquid chamber 8a is equal to the volume decrease amount (or volume increase amount) of the second liquid chamber 8b. Further, the pressure loss of the liquid flowing into the head portion 6 from the supply path 5 via the first liquid chamber 8a and the pressure loss of the liquid flowing into the head portion 6 from the supply path 5 via the second liquid chamber 8b. And are equal. Therefore, the supply path 5 is connected to the flow path point X of the communication flow path 4 where the flow path resistances to the first and second liquid chambers 8a and 8b are equal. Furthermore, the flow path resistance from the first liquid chamber 8a to the head part 6 and the flow path resistance from the second liquid chamber 8b to the head part 6 are configured to be equal. As a result, the movement of the common wall 11 contributes only to the circulation of the liquid, and is not affected by the movement of the common wall 11 when ejecting droplets from the head unit 6. When the liquid droplets are discharged from the nozzle 9 and the liquid in the internal flow path 7 c is consumed, the pressure in the internal flow path 7 c decreases and the liquid is replenished from the supply path 5.

  Instead of fixing the outer frame 10 and moving the common wall 11 left and right as a movable wall, the common wall 11 may be fixed and the outer frame 10 moved left and right. In this case, the movable wall is a side wall that is not common to the two liquid chambers 8. That is, the movable wall is a side wall composed of the outer walls 12a and 12b that are not common to the two liquid chambers and the bellows structure.

  Also in this embodiment, the liquid of the head unit 6 can be circulated with a simple configuration without using a complicated control system. The circulation unit 2 can be stopped and used at the time of recording by the head unit 6 and can be used for maintenance. For example, the movable wall 3 is stopped during the recording operation of the head unit 6, the liquid is supplied to the head unit 6 via the first liquid chamber 8a and the second liquid chamber 8b, and the operating wall 3 is moved during maintenance. The liquid is circulated through the head unit 6 to restore nozzle omission and the like. Further, if the communication flow path 4 and the circulation unit 2 are configured integrally with the head unit 6, it is only necessary to connect a single liquid supply tube from the liquid tank to the liquid ejection unit 1. The liquid ejecting unit 1 having the property can be configured.

(Third embodiment)
FIG. 4 is a schematic diagram of the liquid ejecting unit 1 according to the third embodiment of the present invention. The difference from the first and second embodiments is that the first liquid chamber 8a and the second liquid chamber 8b are physically separated, each liquid chamber 8 is provided with a side wall forming a movable wall, and the side wall forming each movable wall is It is a point connected by a connecting member. The same portions or portions having the same function are denoted by the same reference numerals.

  As shown in FIG. 4, the liquid ejecting unit 1 includes a circulation unit 2 including two liquid chambers 8 including a first liquid chamber 8a and a second liquid chamber 8b, and a supply path 5 for supplying liquid. A communication channel 4 that communicates between the liquid chamber 8a and the second liquid chamber 8b, two connection ports 7a and 7b that communicate with the two first and second liquid chambers 8a and 8b, and two connection ports 7a, The head part 6 which has the internal flow path 7c which connects 7b is provided. In the circulation unit 2, the volume increase amount of the first liquid chamber 8a (or the second liquid chamber 8b) is equal to the volume decrease amount of the second liquid chamber 8b (or the first liquid chamber 8a).

  This will be specifically described. The head portion 6 includes a piezoelectric substrate 6b in which a discharge groove 6d is formed, a cover plate 6a having two manifolds 6e that are bonded to the upper surface of the piezoelectric substrate 6b and into and out of the liquid, and a piezoelectric substrate 6b. A nozzle plate 6c having a nozzle 9 bonded to the lower surface and communicating with the discharge groove 6d. Here, the upper openings of the two manifolds 6e form connection ports 7a and 7b, respectively, and the two manifolds 6e and the discharge groove 6d form an internal flow path 7c.

  The circulation unit 2 is installed between the first and second liquid chambers 8a and 8b, which are physically separated and installed between the first liquid chamber 8a and the second liquid chamber 8b, and rotates around the fulcrum Z. And a movable lever 13 which can be fixed. The first liquid chamber 8a is surrounded by the upper wall 14a connected to one end of the movable lever 13 and the side wall of the bellows structure, and the lower part is connected to the connection port 7a of the cover plate 6a. The first liquid chamber 8a communicates with one manifold 6e of the cover plate 6a. The second liquid chamber 8b is surrounded by the upper wall 14b connected to the other end of the movable lever 13 and the side wall of the bellows structure, and the lower part is connected to the connection port 7b of the cover plate 6a. The second liquid chamber 8b communicates with the other manifold 6e of the cover plate 6a. Accordingly, in the first liquid chamber 8a and the second liquid chamber 8b, the upper walls 14a and 14b and the side wall of the bellows structure are movable walls. In other words, the movable wall is a side wall that is not common to the two liquid chambers 8, and the movable lever 13 serves as a connecting member that connects the side walls made of the two movable walls.

  When the movable lever 13 is rotated clockwise around the fulcrum Z by a drive unit (not shown), the second liquid chamber 8b is moved to the first liquid chamber 8a via the discharge groove 6d of the head unit 6 and the communication channel 4. When the liquid is sent out and the movable lever 13 is rotated counterclockwise, the liquid is sent out from the first liquid chamber 8a to the second liquid chamber 8b through the discharge groove 6d of the head portion 6 and the communication flow path 4. The liquid in the head unit 6 circulates. Accordingly, the liquid circulates through the head portion 6 by the reciprocating motion of the movable wall.

  Since the first liquid chamber 8a and the second liquid chamber 8b have the same inner diameter of the bellows, the volume increase amount (or volume decrease amount) of the first liquid chamber 8a and the volume decrease amount (or volume increase amount) of the second liquid chamber 8b. And are equal. Further, the pressure loss of the liquid flowing into the head portion 6 from the supply path 5 via the first liquid chamber 8a and the pressure loss of the liquid flowing into the head portion 6 from the supply path 5 via the second liquid chamber 8b. And are equal. Therefore, the supply path 5 is connected to the flow path point X of the communication flow path 4 where the flow path resistances to the first and second liquid chambers 8a and 8b are equal. Furthermore, the flow path resistance from the first liquid chamber 8a to the head part 6 and the flow path resistance from the second liquid chamber 8b to the head part 6 are configured to be equal. As a result, the movement of the upper walls 14a and 14b contributes only to the circulation of the liquid, and is not affected by the movement of the upper walls 14a and 14b when the liquid droplets are ejected from the head unit 6. When the liquid droplets are discharged from the nozzle 9 and the liquid in the internal flow path 7 c is consumed, the pressure in the internal flow path 7 c decreases and the liquid is replenished from the supply path 5. Here, the upper walls 14a and 14b are removed, and the entire first liquid chamber 8a and the second liquid chamber 8b are constituted by the side wall of the bellows structure, and the end of the movable lever 13 is connected to the upper end of the side wall of the bellows structure. May be. In this case, all of the side walls constituting the liquid chamber are constituted by movable walls.

(Fourth embodiment)
FIG. 5 is a schematic diagram of the liquid ejecting unit 1 according to the fourth embodiment of the present invention. The difference from the first embodiment is that one end of the communication channel 4 communicates with the additional channel 15a and the head side channel 16a at the branch point Ya, and the other end of the communication channel 4 communicates with the additional channel 15b at the branch point Yb. And a point communicating with the head-side flow path 16b. Each of the additional flow paths 15 a and 15 b communicates with two inner spaces of the cylinder S divided by the movable wall 3, and each of the head side flow paths 16 a and 16 b communicates with the connection ports 7 a and 7 b of the head portion 6. Other configurations are the same as those of the first embodiment. The same portions or portions having the same function are denoted by the same reference numerals.

  As shown in FIG. 5, the circulation unit 2 includes a cylinder S that accommodates the movable wall 3 so as to be reciprocally movable, a communication channel 4 to which the supply channel 5 is connected, and one end of the communication channel 4 at the branch point Ya. The additional flow path 15a and the head side flow path 16a to be connected, and the additional flow path 15b and the head side flow path 16b to be connected to the other end of the communication flow path 4 at the branch point Yb are provided. When the movable wall 3 moves to the right, the liquid filled in the cylinder S and the additional flow path 15b on the right side of the movable wall 3 becomes the communication flow path 4, the head side flow path 16b, the internal flow path 7c, and the head. The additional flow path 15a and the movable wall 3 are sent to the cylinder S on the left side through the side flow path 16a. When the movable wall 3 moves to the left, the liquid filled in the cylinder S and the additional flow path 15a on the left side of the movable wall 3 becomes the communication flow path 4, the head side flow path 16a, the internal flow path 7c, and the head. The additional flow path 15b and the movable wall 3 are sent to the cylinder S on the right side through the side flow path 16b.

  Here, the first liquid chamber 8a is an inner space included in the broken line Ra, and is located in the inner space of the cylinder S on the left side of the movable wall 3, the inner space of the additional flow path 15a, and the vicinity of the branch point Ya. It consists of the total with the interior space. The second liquid chamber 8b is an inner space included in the broken line Rb, and is an inner space of the cylinder S on the right side of the movable wall 3, an inner space of the additional flow path 15b, and an inner space near the branch point Yb. It consists of the total with space. Since the movable wall 3 is a side wall common to the first liquid chamber 8a and the second liquid chamber 8b, the volume change amount of the first liquid chamber 8a is equal to the volume change amount of the second liquid chamber 8b. Further, since the vicinity of each of the branch points Ya and Yb is the first and second liquid chambers 8a and 8b, the communication channel 4 communicates with the first and second liquid chambers 8a and 8b at both ends.

  Furthermore, the pressure loss of the liquid flowing into the head part 6 from the supply path 5 via the branch point Ya and the head side flow path 16a, and the flow from the supply path 5 to the head part 6 via the branch point Yb and the head side flow path 16b. Make the pressure drop of the liquid equal. Therefore, the supply path 5 is connected to the flow path point X of the communication flow path 4 where the flow path resistances between the branch point Ya and the branch point Yb are equal. Further, the flow resistance from the branch point Ya to the internal flow path 7c through the head side flow path 16a and the connection port 7a, and the flow from the branch point Yb to the internal flow path 7c through the head side flow path 16b and the connection port 7b. The road resistance is configured to be equal. In the present embodiment, the pressure P1 in the first liquid chamber 8a and the pressure P2 in the second liquid chamber 8b described in the first embodiment are the pressure at the branch point Ya and the pressure at the branch point Yb, respectively. Further, the additional channel 15a and the additional channel 15b may have different channel lengths and channel cross-sectional areas.

  As a result, the same operation as described in the first embodiment can be performed, and the same effect can be obtained. That is, the liquid of the head unit 6 can be circulated with a simple configuration without a complicated control system. In addition, since one liquid supply tube may be connected from the liquid tank to the liquid ejecting unit 1, assembly and adjustment are simplified, and the versatile liquid ejecting unit 1 can be configured. The branch points Ya and Yb, the additional flow paths 15a and 15b, and the head side flow paths 16a and 16b in the present embodiment can be applied to the liquid ejecting unit 1 of the second embodiment or the third embodiment.

  In the first to fourth embodiments, the liquid ejecting unit 1 may include a liquid tank that supplies liquid to the supply path 5 and a liquid pump that supplies liquid to the supply path 5 from the liquid tank. it can.

(Fifth embodiment)
FIG. 6 is a schematic perspective view of a liquid ejecting apparatus 30 according to the fifth embodiment of the present invention. The liquid ejecting apparatus 30 includes a moving mechanism 40 that reciprocates the liquid ejecting units 1 and 1 ′, and a flow path unit that supplies the liquid to the liquid ejecting units 1 and 1 ′ and discharges the liquid from the liquid ejecting units 1 and 1 ′. 35, 35 ′, liquid pumps 33, 33 ′ and liquid tanks 34, 34 ′ communicating with the flow path portions 35, 35 ′. The liquid ejecting units 1 and 1 ′ use any of the first to fourth embodiments already described.

  The liquid ejecting apparatus 30 includes a pair of conveying units 41 and 42 that convey a recording medium 44 such as paper in the main scanning direction, liquid ejecting units 1 and 1 ′ that eject liquid to the recording medium 44, and a liquid ejecting unit. 1, 1 ′, a carriage unit 43, liquid pumps 33, 33 ′ that supply the liquid stored in the liquid tanks 34, 34 ′ to the flow path portions 35, 35 ′, and the liquid ejection units 1, And a moving mechanism 40 that scans 1 ′ in the sub-scanning direction orthogonal to the main scanning direction. A control unit (not shown) controls and drives the liquid ejecting units 1, 1 ′, the moving mechanism 40, and the conveying means 41, 42.

  The pair of conveying means 41 and 42 includes a grid roller and a pinch roller that extend in the sub-scanning direction and rotate while contacting the roller surface. A grid roller and a pinch roller are moved around the axis by a motor (not shown), and the recording medium 44 sandwiched between the rollers is conveyed in the main scanning direction. The moving mechanism 40 couples a pair of guide rails 36 and 37 extending in the sub-scanning direction, a carriage unit 43 slidable along the pair of guide rails 36 and 37, and the carriage unit 43 to move in the sub-scanning direction. An endless belt 38 is provided, and a motor 39 that rotates the endless belt 38 via a pulley (not shown) is provided.

  The carriage unit 43 mounts a plurality of liquid ejecting units 1, 1 ′, and ejects, for example, four types of liquid droplets of yellow, magenta, cyan, and black. The liquid tanks 34 and 34 'store liquids of the corresponding colors and supply them to the liquid ejecting units 1 and 1' via the liquid pumps 33 and 33 'and the flow path portions 35 and 35'. Each liquid ejecting unit 1, 1 ′ ejects droplets of each color according to the drive signal. An arbitrary pattern is recorded on the recording medium 44 by controlling the timing of discharging the liquid from the liquid ejecting units 1, 1 ′, the rotation of the motor 39 that drives the carriage unit 43, and the conveyance speed of the recording medium 44. be able to.

  In this embodiment, the moving mechanism 40 moves the carriage unit 43 and the recording medium 44 to perform recording, but instead, the carriage unit is fixed and the moving mechanism is the recording medium. It may be a liquid ejecting apparatus that records the image by moving it two-dimensionally. That is, the moving mechanism may be any mechanism that relatively moves the liquid ejecting unit and the recording medium. Further, the liquid tanks 34 and 34 'are opened to the atmosphere, and the liquid pumps 33 and 33' are filled with liquid in the liquid ejecting units 1 and 1 'at the start of recording, and then stopped in an open state, and the liquid tanks 34 and 34' The liquid may be fed by a water head difference between the liquid ejecting units 1 and 1 ′.

DESCRIPTION OF SYMBOLS 1 Liquid injection unit 2 Circulation unit 3 Movable wall 4 Communication flow path 5 Supply path 6 Head part, 6a Cover plate, 6b Piezoelectric substrate, 6c Nozzle plate, 6d Discharge groove, 6e Manifold 7a, 7b Connection port, 7c Internal flow path 8 liquid chamber, 8a first liquid chamber, 8b second liquid chamber 9 nozzle 10 outer frame 11 common wall 12a, 12b outer wall 13 movable lever 14a, 14b upper wall 15a, 15b additional flow path 16a, 16b head side flow path X flow Road point, N nozzle surface, Z fulcrum, S cylinder

Claims (13)

A circulation unit comprising two liquid chambers;
A supply channel for supplying liquid, and a communication channel communicating with the two liquid chambers;
A head portion having two connection ports communicating with each of the two liquid chambers, and an internal flow path communicating the two connection ports;
The circulation unit is a liquid ejecting unit in which the volume increase amount of one of the liquid chambers is equal to the volume decrease amount of the other liquid chamber.   The liquid supply unit according to claim 1, wherein the supply path is connected to a flow path point of the communication flow path where flow path resistances to the liquid chambers are equal.   The pressure loss of the liquid flowing into the head part from the supply path via the one liquid chamber and the pressure loss of the liquid flowing from the supply path to the head part via the other liquid chamber are: The liquid ejecting unit according to claim 1 or 2, which is equal.   4. The liquid ejecting unit according to claim 1, wherein the circulation unit is configured such that a part or all of the side walls constituting each of the liquid chambers is a movable wall.   The liquid ejecting unit according to claim 4, wherein the movable wall includes a side wall common to the two liquid chambers.   The liquid ejecting unit according to claim 4, wherein the movable wall includes a side wall common to the two liquid chambers and a side wall not common to the two liquid chambers.   The liquid ejecting unit according to claim 5, wherein a side wall common to the two liquid chambers is made of a flexible film.   The liquid ejecting unit according to claim 4, wherein the movable wall includes a side wall that is not common to the two liquid chambers.   The liquid ejecting unit according to claim 8, wherein two side walls forming the movable wall of the two liquid chambers are connected by a connecting member.   10. The liquid ejecting unit according to claim 6, wherein a side wall forming the movable wall not common to the two liquid chambers has a bellows structure.   The liquid ejecting unit according to claim 4, wherein the movable wall reciprocates.   The liquid ejecting unit according to claim 1, further comprising a liquid tank that supplies liquid to the supply path. A liquid ejecting unit according to claim 1;
A moving mechanism for relatively moving the liquid ejecting unit and the recording medium;
A liquid ejecting apparatus comprising: a liquid tank that supplies liquid to the supply path.

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