JP5825908B2 - Liquid ejection device - Google Patents

Description

  The present invention relates to an ink jet apparatus that discharges ink from an ink jet head, and more particularly to a negative pressure control mechanism of an ink tank.

  As one of printing methods, an ink jet method for ejecting ink droplets from a recording head has been devised, and in recent years, it has been used in various fields. In such an ink jet apparatus, it is necessary to control the internal pressure of the ink tank in order to stably maintain the ink meniscus state at the nozzles of the recording head and to ensure ejection stability. On the other hand, a flexible container is often used as an ink tank, and the volume of such an ink tank changes as ink is ejected. The following techniques are known as methods for controlling the internal pressure of the ink tank whose volume changes.

  Patent Documents 1 and 2 disclose an inkjet apparatus in which a flexible ink tank is accommodated in an accommodating portion. In the configuration described in Patent Document 1, the housing portion is connected to a vacuum pump. When a change in the volume of the ink tank is detected, the inside of the storage unit is set to a predetermined negative pressure by a vacuum pump based on the detected change in the volume. As a result, the volume of the ink tank changes, and the internal pressure of the ink tank can be controlled. In the configuration described in Patent Document 2, the inside of the ink tank is maintained at a negative pressure by pressing the plate member joined to the ink tank from the inside of the ink tank by the negative pressure generating spring. When the negative pressure of the ink tank increases due to ink ejection, the one-way valve provided in the housing portion is pushed by the plate member, the atmosphere is introduced into the ink tank, and the internal pressure of the ink tank is restored.

Japanese Patent No. 3803108 JP 2009-023108 A

  In the configuration disclosed in Patent Document 1, the amount of deformation of the ink tank itself is controlled by controlling the external pressure of the ink tank, that is, the negative pressure of the container, and thereby the internal pressure of the ink tank is controlled. However, in order to control the negative pressure of the accommodating part, the hermeticity of the accommodating part is required, and equipment for applying and maintaining the negative pressure is also required. For this reason, the influence on apparatus cost and operation cost is great. Since the deformation amount of the ink tank is not directly controlled, it is difficult to improve control accuracy.

  In the configuration disclosed in Patent Document 2, since the negative pressure is controlled only by expansion and contraction of the negative pressure generating spring and the deformation of the ink tank, it is difficult to control the internal pressure with high accuracy. Further, since the negative pressure generating spring and the one-way valve are provided inside the ink tank, fine foreign matters may be generated during these operations and mixed into the ink. Such foreign matter may cause defects in the product.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet apparatus that can accurately control the internal pressure of an ink tank with a simple configuration and that is less likely to generate foreign matter inside the ink tank.

Ink jet apparatus of the present invention, a Ruhe head for discharging a liquid, communicating with the F head accommodates a liquid to be supplied to the F head, a main tank capable of volume change, the outer surface of the main tank the linked primary and volume reduction mechanism for reducing the main tank volume by deforming a portion of the tank, the internal pressure detecting means for detecting the internal pressure of the main reservoir, pressure of the internal pressure detecting means detects the predetermined value And a volume reduction mechanism control unit that activates the volume reduction mechanism when the value falls below . In one aspect, the volume reduction mechanism has an elastic body at a connection portion with the main tank, and the internal pressure detection means includes a detection plate attached to the volume reduction mechanism, a position detection unit attached to the main tank, The position detection unit detects a relative position with respect to the detection plate by moving with a change in the volume of the main tank. In another aspect, it has a flexible auxiliary tank that communicates with the main tank, has an internal pressure decrease mitigation mechanism that mitigates a decrease in the internal pressure of the main tank caused by the discharge of liquid from the head, and the internal pressure detection means includes: It has a detection plate that is attached to the auxiliary tank and moves as the volume of the auxiliary tank changes, and a position detection unit that detects the position of the detection plate.

  In the present invention, the volume of the main ink tank is changed by the volume reduction mechanism as ink is ejected from the inkjet head. The volume reduction mechanism is connected to the outer surface of the main ink tank, and reduces the volume of the main ink tank by deforming a part of the main ink tank. For this reason, the volume of the main ink tank can be directly controlled with a simple configuration. Since the volume reduction mechanism abuts on the outer surface of the main ink tank, it is possible to prevent the generation of foreign matter in the main ink tank due to the operation of the volume reduction mechanism.

  According to the present invention, it is possible to provide an ink jet apparatus that can accurately control the internal pressure of an ink tank with a simple configuration and that is less likely to generate foreign matter inside the ink tank.

It is sectional drawing of the apparatus main body of the inkjet apparatus of 1st Embodiment. It is principal part sectional drawing of the head cartridge of 1st Embodiment. It is principal part sectional drawing of the inkjet apparatus of 1st Embodiment. FIG. 6 is a cross-sectional view of the main part showing the operation of the head cartridge. It is a flowchart which shows the procedure which controls the internal pressure of an ink tank. It is sectional drawing which shows the form with which the drive motor was provided in the head cartridge. It is sectional drawing which shows the form with which the main and auxiliary ink tank parts were directly connected. It is sectional drawing which shows the form with which the inkjet head was mounted in the apparatus main body. FIG. 3 is a cross-sectional view of a main part of the ink tank unit of the first embodiment. FIG. 3 is a cross-sectional view illustrating a state where the ink tank unit is mounted on the apparatus main body. It is principal part sectional drawing of the inkjet apparatus of 2nd Embodiment. It is principal part sectional drawing of the inkjet apparatus of 3rd Embodiment.

  Several embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of the main part of the main body of the ink jet apparatus of the present invention, showing a state in which the head cartridge 8 is not mounted. A base plate 2 is installed in the apparatus main body 1, and a substrate to be printed is mounted on the base plate 2. A printed material 4 is mounted on the printed material transport unit 3 by a suction unit (not shown).

  The apparatus main body 1 is equipped with a drive motor 6 and a drive motor magnet unit 7 that constitute a part of a volume reduction mechanism 35 (described later). The drive motor magnet unit 7 is connected to the drive shaft of the drive motor 6. The apparatus main body 1 is provided with a head cartridge mounting portion 5. The apparatus main body 1 also includes a volume reduction mechanism control unit 19 for controlling the volume reduction mechanism 35.

  FIG. 2 is a cross-sectional view of the main part of the head cartridge 8. FIG. 3 is a cross-sectional view of the main part of the ink jet apparatus 41 showing a state where the head cartridge 8 is mounted on the apparatus main body 1. The head cartridge 8 is configured to be detachable from the apparatus main body 1. The head cartridge 8 is provided with an ink jet head 16 that ejects ink and a main ink tank 9 that stores ink supplied to the ink jet head 16. The apparatus main body 1 and the head cartridge 8 are electrically connected, and the main ink tank 9 communicates with a nozzle 17 provided on the ink jet head 16. Therefore, the ink 18 in the main ink tank 9 is ejected from the nozzle 17 as the droplet 20 by transmitting the ejection signal from the apparatus main body 1 to the head cartridge 8. The discharged liquid is typically ink, but may be a conductive liquid, an ultraviolet (UV) curable liquid, or the like. The main ink tank 9 is made of a highly deformable material such as resin, and has a plurality of bent portions 9a on the side surface. Accordingly, the main ink tank 9 can be deformed and its volume can be changed.

  The volume reduction mechanism 35 includes a male screw portion 10 in which a male screw is formed, a female screw portion 11 in which a female screw that engages with the male screw is formed, a rotation drive mechanism 36 that is connected to the female screw portion 11 and rotationally drives the female screw portion 11, have. The volume reduction mechanism 35 is connected to the outer surface (main ink tank plate 25) of the main ink tank 9, and reduces the volume of the main ink tank 9 by deforming a part of the main ink tank 9.

  In the present embodiment, the male screw portion 10 and the female screw portion 11 and a part of the rotation drive mechanism 36 are built in the head cartridge 8. Specifically, the external thread portion 10 that changes the volume of the main ink tank 9 is connected to the main body of the main ink tank 9 via a main ink tank plate 25 that constitutes a part of the outer surface of the main ink tank 9. Yes. The external thread of the external thread part 10 engages with the internal thread of the internal thread part 11, and the internal thread part 11 is connected to the magnet part 12. The magnet unit 12 is rotatably supported by the magnet support unit 13. The magnet unit 12 and the magnet support unit 13 constitute a part of the rotation drive mechanism 36. As shown in FIG. 3, by mounting the head cartridge 8 on the apparatus main body 1, the drive motor magnet unit 7 and the magnet unit 12 are magnetically coupled (magnet coupling). That is, the female screw portion 11 that is rotationally driven and the rotational drive mechanism 36 are magnetically coupled via the ink cartridge 8.

  In a state where the rotational driving force is not applied to the female screw portion 11, rotation of the male screw portion 10 is prevented by a static frictional force acting between the male screw and the female screw. For this reason, the volume of the main ink tank 9 does not change.

  When the internal thread 11 is rotated counterclockwise when viewing FIG. 2 from the direction A, the external thread 10 moves downward in FIG. When the female screw portion 11 is rotated clockwise, the male screw portion 10 moves upward in FIG. The arrangement of the male screw and the female screw may be reversed.

  The head cartridge 8 has an internal pressure reduction mitigation mechanism 37 that mitigates a decrease in internal pressure of the main ink tank 9 caused by ink ejection. In the present embodiment, the internal pressure reduction mitigation mechanism 37 includes a flexible auxiliary ink tank 14 that communicates with the main ink tank 9, and a communication portion 15 that communicates the main ink tank 9 and the auxiliary ink tank 14. ing. The ink 18 can move between the main ink tank 9, the communication portion 15, and the auxiliary ink tank 14. That is, the portion of the main ink tank 9, the communication portion 15, and the auxiliary ink tank 14 combined is an actual ink storage portion. The auxiliary ink tank 14 has lower rigidity than the main ink tank 9 and can easily change its volume. The present invention is not limited by the ink capacity, but is particularly suitable when the ink capacity of the main ink tank 9 is large.

  The internal pressure reduction mitigating mechanism 37 is further provided with a pretensioned elastic body (ink tank) having one end attached to the auxiliary ink tank 14 and the other end attached to the head cartridge 8 (that is, immovable with respect to the apparatus main body 1). Spring 26). The pretension generates a negative pressure suitable for discharging the droplet 20 from the nozzle 17 to the ink 18 in the main ink tank 9, the communication portion 15, and the auxiliary ink tank 14. When the head cartridge 8 is transported, the volume of the main ink tank 9 does not change as described above, and since the capacity of the auxiliary ink tank 14 is small, the ink 18 drips from the nozzle 17 because it is not easily affected by disturbance. Can be prevented.

  The head cartridge 8 has an internal pressure detecting means for detecting the internal pressure of the main ink tank 9. The internal pressure detection means includes a strain gauge 22 that is attached to the communication portion 15 and detects deformation of the communication portion 15. As the pressure inside the main ink tank 9 changes, the wall surface of the communication portion 15 is bent, and the amount of bending is measured by the strain gauge 22.

  The volume reduction mechanism control unit 19 operates the volume reduction mechanism 35 when the internal pressure detected by the internal pressure detection means falls below a predetermined value. The amount of deflection of the communication portion 15 measured by the strain gauge 22 is transmitted to the volume reduction mechanism control portion 19 and converted into the internal pressure of the main ink tank 9. The volume reduction mechanism control unit 19 drives the drive motor 6 based on the calculated internal pressure of the main ink tank 9. By driving the drive motor 6, the drive motor magnet unit 7 rotates and the magnet unit 12 rotates. As a result, the internal thread portion 11 rotates and the external thread portion 10 moves up and down to change the volume of the main ink tank 9.

  When the operation of the apparatus is stopped or when the power supply is shut off during the operation of the apparatus, the rotation of the male screw portion 10 is prevented by the static frictional force of the screw as described above. For this reason, the volume of the main ink tank 9 does not change, and the ink 18 is prevented from dripping from the nozzles 17. Even when the head cartridge 8 is removed from the apparatus main body 1, the ink 18 does not drip from the nozzle 17.

  4A to 4C are cross-sectional views of the main part showing the operation of the head cartridge 8 mounted on the apparatus main body 1. As shown in FIG. 4A, the droplet 20 is ejected from the nozzle 17 of the inkjet head 16 by the ejection signal being transmitted from the apparatus main body 1 to the head cartridge 8.

  By ejecting the droplet 20 from the nozzle 17, the ink 18 inside the main ink tank 9 decreases. For this reason, as shown in FIG. 4B, the negative pressure of the main ink tank 9 increases. Part of the ink stored in the auxiliary ink tank 14 moves to the main ink tank 9, and the internal pressure of the main ink tank 9 is restored. Although the volume of the auxiliary ink tank 14 is reduced, since the ink tank spring 26 is extended, a sudden change in the internal pressure of the main ink tank 9 is prevented.

  Since the internal pressure of the main ink tank 9 gradually decreases as ink is ejected, the wall surface of the communication portion 15 bends inward (the flow path is narrowed). The amount of bending of the wall surface is measured with a strain gauge 22 attached to the communication portion 15. The amount of deflection of the communication portion 15 measured by the strain gauge 22 is transmitted to the volume reduction mechanism control portion 19 and converted into the internal pressure of the main ink tank 9.

  The volume reduction mechanism control unit 19 controls the internal pressure of the main ink tank 9 within a certain range based on the calculated internal pressure of the main ink tank 9. When the negative pressure of the main ink tank 9 becomes high, the drive motor 6 is rotated counterclockwise when FIG. 4C is viewed from the B direction. As a result, the female screw portion 11 rotates counterclockwise, and the male screw portion 10 descends in FIG. When the male screw portion 10 is lowered and the main ink tank plate 25 is lowered, the bending angle of the bent portion 9a on the side surface of the main ink tank 9 is changed, and the volume of the main ink tank 9 is reduced.

  As a result, the internal pressure of the main ink tank 9 increases (the negative pressure is weakened), a part of the ink in the main ink tank 9 moves to the auxiliary ink tank 14, and the volume of the auxiliary ink tank 14 is restored. The ink tank spring 26 contracts again, and the wall surface of the communicating portion 15 is also eliminated. When the internal pressure of the main ink tank 9 converted from the amount of deflection measured by the strain gauge 22 falls within a certain range, the drive of the drive motor 6 is stopped by a signal from the volume reduction mechanism control unit 19. In this way, the internal pressure of the main ink tank 9 is controlled within a certain range, the meniscus state of the nozzle 17 is stably maintained, and the ejection stability from the nozzle 17 can be ensured.

  FIG. 5 is a flowchart showing a procedure for controlling the internal pressure of the main ink tank 9 based on the measurement result of the deflection amount of the wall surface of the communication portion 15 measured by the strain gauge 22. In step S50, droplets are ejected from the nozzle 17. In step S51, the distortion amount of the wall surface of the communication portion 15 is detected by the strain gauge 22. In step S <b> 52, the volume reduction mechanism control unit 19 converts the deflection amount into the internal pressure of the main ink tank 9. In step S53, it is determined whether or not the pressure in the main ink tank 9 is within a certain range. If the pressure in the main ink tank 9 is not within a certain range, the drive motor 6 is driven in step S54. In step S <b> 55, the male screw portion 10 is lowered, and the volume of the main ink tank 9 is reduced by applying an external force (pressing force) to the main ink tank 9. Next, the process proceeds to step S51, and steps S52 and S53 are executed. If the pressure in the main ink tank 9 is within a certain range in step S53, the procedure ends. Measurement of the amount of bending of the wall surface of the communication portion 15 is always performed. For this reason, in FIGS. 4A to 4C, the volume of the auxiliary ink tank 14 is greatly changed for easy understanding, but the volume change of the auxiliary ink tank 14 is actually small. .

  Thus, when one screw portion is driven to rotate, the end portion of the other screw portion connected to the ink tank 9 moves, and a part of the main ink tank 9 (main ink tank plate 25) is moved. As a result, the volume of the main ink tank 9 is reduced. Therefore, the internal pressure of the main ink tank 9 can be controlled within a certain range with a simple configuration, and the ejection stability from the nozzle 17 can be ensured. Further, the main ink tank 9 and the inkjet head 16 are directly connected without a tube or the like interposed therebetween, and no sliding member such as a valve is used. For this reason, it is possible to prevent fine foreign matter (dust) from entering the ink.

  As shown in FIG. 6, the drive motor 6 may be provided in the head cartridge 8. In this embodiment, the ink cartridge 8 detachable from the apparatus main body 1 contains at least the main ink tank 9, the male screw part 10 and the female screw part 11 of the volume reduction mechanism 35, and the rotation drive mechanism 36. Yes. A drive motor gear 33 is provided in the drive motor 6, and the drive motor gear 33 is interlocked with a main ink tank gear 34 provided in the female screw portion 11.

  As shown in FIG. 7, a strain gauge 22, which is an internal pressure detecting means, may be attached to the main ink tank 9 to detect the amount of deflection of the bottom surface of the main ink tank 9. The internal pressure of the main ink tank 9 is converted from the amount of bending of the bottom surface of the main ink tank 9. In this embodiment, it is not necessary to provide the communication portion 15, and the auxiliary ink tank 14 can be directly connected to the main ink tank 9 (the communication portion 15 can also be provided).

  In the above-described embodiment, the inkjet head 16 is configured integrally with the ink cartridge 8, but the inkjet head 16 may be configured integrally with the apparatus main body 1. In this case, the inkjet head 16 in the head cartridge 8 is separated from other parts. Such a configuration will be described with reference to FIGS. FIG. 8 is a view showing the apparatus main body 1 on which the inkjet head 16 is mounted. The inkjet head 16 is provided with a nozzle 17, a head filter 28, and a head O-ring 29. The head filter 28 is a filter having fine pores. In addition, it is possible to provide a portion for mounting the inkjet head 16 on the head cartridge mounting portion 5 so that the inkjet head 16 can be attached to and detached from the apparatus main body 1.

  FIG. 9 is a cross-sectional view of the main part of the ink tank unit 32. The ink tank unit 32 is provided with an ink tank filter 30 and an O-ring contact portion 31. The ink tank filter 30 is a filter having fine pores, and the meniscus of ink in the pores of the filter and the negative pressure of the main ink tank 9 are balanced. This prevents ink from dripping from the ink filter 30. Other configurations of the ink tank unit 32 are the same as those of the head cartridge 8 described with reference to FIG.

  FIG. 10 shows a state where the ink tank unit 32 is mounted on the inkjet head 16. The head O-ring 29 provided in the inkjet head 16 and the O-ring contact portion 31 provided in the ink tank unit 32 are brought into close contact with each other, so that air is introduced from the gap between the inkjet head 16 and the ink tank unit 32. It is prevented. The ink 18 in the main ink tank 9 is filled into the nozzle 17 of the inkjet head 16 via the ink tank filter 30 and the head filter 28 by sucking out the ink from the nozzle 17 of the inkjet head 16 by a suction means (not shown). be able to.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG. FIG. 11 is a cross-sectional view of the main part of the ink jet apparatus 141 when the head cartridge 108 is mounted on the apparatus main body 101. In the second embodiment, a detection plate 123 attached to the auxiliary ink tank 114 and a displacement amount detection unit 124 attached to the head cartridge 108 are provided as internal pressure detection means. The detection plate 123 can move in the vertical direction as the volume of the auxiliary ink tank 114 changes, and the displacement detection unit 124 detects the relative displacement of the detection plate 123 relative to the cartridge 108. Other configurations are the same as those of the first embodiment. In addition, the code | symbol which added 100 to the code | symbol of the corresponding member of 1st Embodiment or a similar member is attached | subjected to the member shown in figure.

  By ejecting the droplet 120 from the nozzle 117, the ink 118 inside the main ink tank 109 decreases. Therefore, the negative pressure of the main ink tank 109 is increased. A part of the ink stored in the auxiliary ink tank 114 moves to the main ink tank 109, the volume of the auxiliary ink tank 114 decreases, and the internal pressure of the main ink tank 109 recovers. Although the volume of the auxiliary ink tank 114 is reduced, since the ink tank spring 126 is extended, a sudden change in the internal pressure of the main ink tank 109 is prevented.

  As the auxiliary ink tank 114 is deformed, the detection plate 123 attached to the auxiliary ink tank unit 114 moves downward. The position of the detection plate 123 is detected by the position detection unit 124. The relative position data detected by the position detection unit 124 with respect to the position detection unit 124 of the detection plate 123 is transmitted to the volume reduction mechanism control unit 119 and converted into the internal pressure of the main ink tank 109.

  The volume reduction mechanism control unit 119 controls the internal pressure of the main ink tank 109 within a certain range based on the internal pressure of the main ink tank 109. When the negative pressure of the main ink tank 109 becomes high, the drive motor 106 is rotated counterclockwise when FIG. 11 is viewed from the C direction. As a result, the internal thread portion 111 rotates counterclockwise, and the external thread portion 110 moves downward in FIG.

  As a result, the internal pressure of the main ink tank 109 increases (the negative pressure becomes weak), a part of the ink in the main ink tank 109 moves to the auxiliary ink tank 114, and the volume of the auxiliary ink tank 114 increases. The ink tank spring 126 contracts again, and the detection plate 123 rises. When the internal pressure of the main ink tank 109 converted from the position data of the detection plate 123 falls within a certain range, the drive of the drive motor 106 is stopped by a signal from the volume reduction mechanism control unit 119.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIG. FIG. 12 is a cross-sectional view of the main part of the ink jet apparatus 241 when the head cartridge 208 is mounted on the apparatus main body 201. In the third embodiment, the volume reduction mechanism 235 has an elastic body (ink tank spring 226) in which a pretension is applied to a connection portion with the main ink tank 209. The internal pressure detection means includes a detection plate 223 attached to the volume reduction mechanism 235 and a position detection unit 224 attached to the main ink tank 209. The ink tank spring 226 is provided between the male screw portion 210 and the main ink tank plate 225. The ink tank spring 226 uses a spring having a larger spring constant than the ink tank spring 26 of the first embodiment and the ink tank spring 126 of the second embodiment. Since the spring constant of the ink tank spring 226 is large, the ink tank spring 226 does not easily extend even when a force is applied to the ink tank spring 226 when the head cartridge 208 is transported, and the ink 218 does not easily drip from the nozzle 217. It has become. The detection plate 223 is attached to the distal end portion of the male screw portion 210, and the position detection portion 224 is fixed to the main ink tank plate 225. Other configurations are the same as those of the first embodiment. In addition, the code | symbol which added 200 to the code | symbol of the corresponding member of 1st Embodiment or a similar member is attached | subjected to the member shown in figure.

  By ejecting the droplets 220 from the nozzles 217, the ink 218 inside the main ink tank 209 decreases. Therefore, the negative pressure of the main ink tank 209 is increased, the main ink tank 209 is reduced downward as a whole, and the ink tank spring 226 is extended. The position detection unit 224 detects the relative position of the detection plate 223 with respect to the position detection unit 224 while descending relative to the detection plate 223. That is, the position detection unit 224 detects the relative position with respect to the detection plate 223 by moving with the change in the volume of the main ink tank 209. The position data of the detection plate 223 detected by the position detection unit 224 is transmitted to the volume reduction mechanism control unit 219 and converted into the internal pressure of the main ink tank 209.

  The volume reduction mechanism control unit 219 controls the internal pressure of the main ink tank 209 within a certain range based on the internal pressure of the main ink tank 209. When the negative pressure of the main ink tank 209 increases, the drive motor 206 is rotated counterclockwise when FIG. 12 is viewed from the D direction. As a result, the female screw portion 211 rotates counterclockwise, and the male screw portion 210 moves downward in FIG.

  As a result, the internal pressure of the main ink tank 209 increases (the negative pressure becomes weak), and the volume of the main ink tank 209 decreases. When the internal pressure of the main ink tank 209 converted from the position data of the detection plate 223 falls within a certain range, the drive of the drive motor 206 is stopped by a signal from the volume reduction mechanism control unit 219. As described above, since the spring constant of the ink tank spring 226 is large, in order to finely control the internal pressure of the main ink tank 209, the position of the detection plate 223 with respect to the position detection unit 224 is detected finely and the drive motor 206 is driven. Need to be finely controlled.

16, 116, 216 Inkjet head 9, 109, 209 Main ink tank 35, 235 Volume reduction mechanism 41, 141, 241 Inkjet device

Claims (12)

And Ruhe head for discharging a liquid,
Before Kihe Tsu communicating with prior Kihe head housing the liquid to be supplied to the de a main tank capable of volume change,
A volume reduction mechanism for reducing the volume of the main tank by causing coupled to an outer surface of said main tank deforming a portion of the main tank,
An internal pressure detecting means for detecting an internal pressure of the main tank;
In a liquid ejection apparatus comprising: a volume reduction mechanism control unit that operates the volume reduction mechanism when the internal pressure detected by the internal pressure detection means falls below a predetermined value.
The volume reduction mechanism has an elastic body at a connection portion with the main tank,
The internal pressure detection means includes a detection plate attached to the volume reduction mechanism, and a position detection unit attached to the main tank,
The position detection unit detects a relative position with respect to the detection plate by moving with a change in the volume of the main tank . The liquid ejection apparatus according to claim 1, further comprising a head cartridge that accommodates the head and the main tank. A head for discharging liquid;
  A main tank capable of changing volume, containing the liquid supplied to the head and communicating with the head;
  A volume reduction mechanism connected to an outer surface of the main tank and reducing a volume of the main tank by deforming a part of the main tank;
  An internal pressure detecting means for detecting an internal pressure of the main tank;
  In a liquid ejection apparatus comprising: a volume reduction mechanism control unit that operates the volume reduction mechanism when the internal pressure detected by the internal pressure detection means falls below a predetermined value.
  A flexible auxiliary tank that communicates with the main tank, and an internal pressure reduction mitigation mechanism that mitigates a decrease in internal pressure of the main tank caused by discharge of the liquid from the head,
  The internal pressure detection means includes a detection plate that is attached to the auxiliary tank and moves in accordance with a change in the volume of the auxiliary tank, and a position detection unit that detects the position of the detection plate. apparatus. The internal pressure decreases relaxation mechanism has a communicating portion for communicating with the auxiliary tank and the main tank,
The liquid ejection apparatus according to claim 3 , wherein the internal pressure detection unit includes a strain gauge that is attached to the communication portion and detects deformation of the communication portion. A head cartridge that houses the head, the main tank, and the internal pressure reduction mitigation mechanism;
The internal pressure decreases relief mechanism has one end and the other end to the auxiliary tank is attached to the head cartridge has an elastic body provided pretensioned, liquid ejecting apparatus according to claim 3 or 4. It said pressure sensing means is mounted on said main tank, with a strain gauge for detecting a deformation of the main tank, the liquid ejecting apparatus according to claim 3. The volume reduction mechanism includes a male screw portion having a male screw, a female screw portion having a female screw that engages with the male screw, and a rotational drive mechanism that is connected to one of the male screw portion and the female screw portion and rotationally drives the one screw portion. When have, said end of the other threaded portion deforms a portion of the main tank by one of the threaded portion is rotationally driven, thereby reducing the volume of the main tank, according to claim 2 or 5. The liquid ejection device according to 5 . The head cartridge further accommodates the male screw portion and the female screw portion of the volume reduction mechanism,
  The rotation driving mechanism of the volume reduction mechanism is provided in an apparatus main body, and the one screw portion to be rotationally driven and the rotation driving mechanism are magnetically coupled via a wall of the head cartridge. Item 8. The liquid ejection device according to Item 7. The liquid ejecting apparatus according to claim 7, wherein the head cartridge further accommodates the male screw portion and the female screw portion of the volume reduction mechanism, and the rotation driving mechanism. The liquid ejecting apparatus according to claim 8, wherein the head cartridge is configured to be detachable from the apparatus main body. Before Kihe head is formed integrally with the apparatus main body, the liquid ejecting apparatus according to any one of claims 1 9. Before Kihe head is detachably attached to the apparatus main body, the liquid ejecting apparatus according to any one of claims 1 10.

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