Liquid discharge device

Abstract

To provide a liquid discharge device that is simply configured and can suppress increase in the number of components and cost and can open a peripheral region of a flexible part to the atmosphere.SOLUTION: A liquid discharge device includes an atmosphere communication part 830 in a cylinder 813 of a booster pump 801.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a liquid ejection device that ejects liquid (hereinafter also referred to as ink) from within a recording head. [Background technology]

[0002] Patent Document 1 discloses that the flexible part is deformed by air pressure to apply pressure to the ink flow path. When applying pressure using air pressure, it is necessary to adjust the air pressure around the flexible part in order to control the applied pressure. One method of adjustment is to connect the flexible part to the atmosphere to set it to atmospheric pressure, and then cut off communication with the atmosphere to apply pressure from that state. By resetting the air pressure around the flexible part to atmospheric pressure before changing the pressure and performing a specified operation, it is possible to apply pressure to approximately the same pressure every time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-260182 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the mechanism for opening to the atmosphere in Patent Document 1 has a complex configuration in that when the valve body is pressed down and the opening separates from the seal portion, the space communicates with the atmosphere via the opening.

[0005] There is also a method of adjusting the pressure by providing a sensor that detects the pressure without opening the pressure to the atmosphere, but this method raises concerns about an increase in the number of parts and costs.

[0006] Therefore, the present invention provides a liquid ejection device that can open the area around the flexible portion to the atmosphere with a simple configuration. [Means for solving the problem]

[0007] Therefore, the liquid ejection device of the present invention comprises a recording head which ejects liquid contained therein, a volume change section formed by a flexible member, a pressurizing mechanism capable of changing the volume of the volume change section to pressurize the inside of the recording head, and a pressurizing pump which changes the volume of the volume change section by sending air to the pressurizing mechanism, wherein the pressurizing pump is a liquid ejection device which pressurizes the air inside a cylinder by moving a piston, thereby pressurizing the inside of the recording head via the volume change section, and the cylinder has an atmosphere communication section on a side of the cylinder which connects the inside of the cylinder to the atmosphere, and is capable of switching between a state in which the inside of the cylinder is connected to the atmosphere and a state in which the inside of the cylinder is sealed, depending on the position of the piston. Effect of the Invention

[0008] According to the present invention, it is possible to provide a liquid ejection device that can open the area around the flexible portion to the atmosphere with a simple configuration. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 illustrates a liquid ejection device. [Diagram 2] FIG. 2 is a block diagram showing an example of the configuration of a control system of the printing apparatus. [Diagram 3] FIG. 2 is a schematic diagram showing the configuration of an ink flow path system. [Figure 4] FIG. 2 is a detailed diagram of the configuration of an ink flow path system. [Diagram 5] FIG. [Figure 6] FIG. 2 is a diagram showing a pressure mechanism and a recording head. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. 13 is a diagram showing a pressure pump according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] FIG. 1 is a diagram showing a liquid ejection device (hereinafter, also referred to as a recording device) 100 to which the present embodiment can be applied. The recording device 100 is connected to a host device 102 in the form of a personal computer or the like, and image information and the like is sent from the host device 102 to the recording device 100. The recording device 100 is equipped with recording heads 101 (101K, 101C, 101M, 101Y) corresponding to each color for recording with pigment ink of black (Bk), cyan (C), magenta (M) and yellow (Y) on a recording medium P, which is roll paper. The recording heads 101 are arranged along the conveying direction (direction of arrow A) of the recording medium P. The recording heads 101 are supplied with ink of each corresponding color from ink tanks 107, which will be described later. Note that in this embodiment, an example corresponding to four colors will be described, but the number of colors is not limited to this.

[0012] The print head 101 is provided with ejection energy generating elements such as electrothermal conversion elements (heaters) and piezoelectric elements, and ejects ink from a number of ejection orifices. For example, when electrothermal conversion elements are used as the ejection energy generating elements, ink is bubbled by heat generation, and the resulting bubble generation energy is used to eject ink from the ejection orifices. The ejection orifices are arranged in a direction intersecting the conveying direction of the print medium P (a direction perpendicular to the drawing). The print head 101 has the form of a so-called long line head, and the length of the arrangement range of the ejection orifices in the print head 101 of this embodiment is longer than the maximum width of the print medium that can be printed on by the printing device 100. The print head 101 is positioned at a predetermined printing position during printing operation.

[0013] The recording device 100 is provided with a recovery unit 104 that performs a process (hereinafter, a recovery process) for maintaining or recovering the ink ejection performance of the recording head 101 in a stable state. The recovery unit 104 is provided with caps 103 that can come into contact with and cover the ejection orifice formation surface (hereinafter, also referred to as the ejection orifice formation surface) of the recording head 101, facing the ejection orifices of each of the recording heads 101K, 101C, 101M, and 101Y. The recovery unit 104 is also provided with known elements associated with the caps 103, such as a wiper that wipes the ejection orifice formation surface, a wiper holding member that holds the wiper, and an ink removing member that removes ink attached to the wiper.

[0014] The recording medium P is supplied from a supply unit 105 and transported in a transport direction (the direction of arrow A) by a transport mechanism 106 incorporated in the recording device 100. The transport mechanism 106 includes a transport belt 106a on which the recording medium P is placed and transported, a transport motor 106b that rotates the transport belt 106a, and rollers 106c that apply tension to the transport belt 106a. The transport mechanism is not limited to the configuration of the transport mechanism 106 shown in the figure, and may be configured to transport the recording medium P using transport rollers, or may be an integrated transport unit.

[0015] When recording on the recording medium P, the recording device 100 selectively ejects ink from an ejection section 101Ks having a plurality of ejection openings of the recording head 101K based on recording data (image information) after the recording start position on the recording medium P during transport reaches under the recording head 101K. Similarly, a color image is recorded on the recording medium P by ejecting ink of each color in the order of the ejection section 101Cs of the recording head 101C, the ejection section 101Ms of the recording head 101M, and the ejection section 101Ys of the recording head 101Y.

[0016] The recording device 100 is provided with ink tanks 107 (107K, 107C, 107M, 107Y) that supply ink to the recording head 101. Furthermore, the recording device 100 is provided with pumps, motors, and the like that supply ink to the recording head 101 and perform recovery processing (hereinafter also referred to as recovery operation).

[0017] 2 is a block diagram showing an example of the configuration of a control system of the recording device 100. Information such as recording data and commands sent from the host device 102 is received by a CPU 202 via an interface controller 201. The CPU 202 is an arithmetic processing device that handles overall control of the recording device 100, such as reception of recording data, recording operations, recovery operations, and handling of the recording medium P. After analyzing the received command, the CPU 202 develops image data of each color component of the recording data into a bitmap in an image memory 204 and records it.

[0018] The CPU 202 is connected to various sensors 217 including a pressure sensor and a photointerrupter, which will be described later, and a valve drive unit 214 that opens and closes a buffer valve, a recovery valve, and a waste liquid valve. When recording an image, the CPU 202 first controls the driving of a capping motor 212 and a head lift motor 210 via an output port 208 and a motor drive unit 209. This causes each recording head (101Y, 101M, 101C, 101K) to move away from the corresponding cap 103 and to a recording position. The capping motor 212 is a motor that moves the cap 103 in the directions of the arrows A1 and A2 in FIG. 1, and the head lift motor 210 is a motor that moves the recording head 101 up and down in the directions of the arrows B1 and B2 in FIG. 1.

[0019] The CPU 202 drives and controls a roll motor (not shown) that feeds out the recording medium P and a conveying motor 106b that conveys the recording medium P at a constant speed, etc., via an output port 208 and a motor driving unit 209, to convey the recording medium P in the conveying direction. The timing (printing timing) of ejecting ink onto the recording medium P conveyed at a constant speed is determined based on the timing of detection of the leading edge of the recording medium P by a leading edge detection sensor (not shown).

[0020] The CPU 202 sequentially reads out the recording data corresponding to each ink color from the image memory 204 in synchronization with the conveyance of the recording medium P, and transfers the read recording data to the corresponding recording head 101 via the recording head control circuit 207. The CPU 202 executes a recording process procedure for performing recording processing and a recovery process procedure for performing recovery processing. The program ROM 203 stores processing programs corresponding to the processing procedures executed by the CPU 202 and tables of fixed data. The work RAM 205 is used as a working memory, etc. During the recovery operation of each recording head 101, the CPU 202 drives and controls the pump motor 213 via the output port 208 and the motor drive unit 209 to pressurize and suck the ink. The CPU 202 also controls the piston motor 810 via the motor drive unit 209 to adjust the pressure in the pressurizing mechanism 304, which will be described later.

[0021] Fig. 3 is a schematic diagram showing the configuration of an ink flow path system in this embodiment, and Fig. 4 is a detailed diagram of the configuration of the ink flow path system. Note that Fig. 3 shows an ink flow path system for one color of ink, but in a configuration using multiple colors of ink (four colors in this embodiment), an ink flow path system as shown in the figure is configured for each color.

[0022] Ink is supplied to the recording head 101 from an ink tank 107 that stores ink through an ink supply flow path 301. The ink supply flow path 301 is provided with a refill valve 302 that can block the ink supply flow path 301, a pressurizing mechanism 304 including a flexible member 303, and a filter 305. The ink tank 107 has an air open portion 107a at the top, and when a flow of ink toward the ink tank 107 is generated, air is released from the air open portion 107a, allowing the ink to flow into the ink tank 107 without resistance.

[0023] The print head 101 includes the above-mentioned ejection section, a storage chamber that stores the ink to be supplied to the ejection section and stores air above the ejection section, and a sensor 306 that detects the liquid level. The liquid level in the print head 101, i.e., the amount of stored ink, is managed by the electrode-type sensor 306. The cap 103 is connected to a buffer chamber 308 via a filter 307 and a recovery valve 316. The cap 103 is provided so as to be able to come into contact with the ejection port forming surface, and moves to an abutting position where the ejection port forming surface is covered by the cap 103, or to a separated position away from the ejection port forming surface. The cap 103 is provided with an air release valve 309 that appropriately opens the space within the cap to the atmosphere in order to alleviate sudden pressure fluctuations that occur in the space within the cap as the cap comes into contact with or separates from the ejection port forming surface.

[0024] The buffer chamber 308 functions to transmit or store pressure for transferring fluid between the recording head 101 and the cap 103 during a pressurized recovery operation or a suction recovery operation, which are recovery operations described later. The buffer chamber 308 also functions to receive ink discharged from the recording head 101 and the cap 103 during a pressurized recovery operation or a suction recovery operation. The buffer chamber 308 has an openable and closable buffer valve 310 at its upper portion that connects the buffer chamber 308 to the atmosphere, and is connected to a waste liquid tank 312 via a pump 311 and a waste liquid flow path 313. The waste liquid tank 312 is configured to be able to store waste liquid collected from the cap 103. Furthermore, the buffer chamber 308 is provided with a pressure sensor 317 that can measure the pressure in the buffer chamber 308.

[0025] In this embodiment, a tube pump capable of blocking a flow path is used as the pump 311, but the pump is not limited to this as long as it is a pump capable of freely generating pressure.

[0026] Operations performed by the recording device 100 using such a flow path system include a recording operation, a pressurization recovery operation, a suction recovery operation, a transfer operation to a waste liquid tank, etc. Depending on the operation to be performed, the refill valve 302, the air release valve 309, the buffer valve 310, and the recovery valve 316 are appropriately opened or closed, and the cap 103 is brought into contact with or separated from the ejection port formation surface.

[0027] During a printing operation, the print head 101 moves to a position further below the position shown in FIG. 1, and at least the refill valve 302 is in an open state.

[0028] During the suction recovery operation, the atmosphere release valve 309, the buffer valve 310, and the recovery valve 316 are all closed, and the cap 103 is brought into contact with the ejection port formation surface of the print head 101. The pump 311 is then driven in the reverse direction to reduce the pressure inside the buffer chamber 308, and when the pressure sensor 317 detects that the pressure inside the buffer chamber 308 has reached a predetermined negative pressure, the recovery valve 316 is opened. The pressure inside the cap 103 is then reduced to suck ink from the print head 101 and receive it in the cap 103. The ink received in the cap 103 is then introduced into the buffer chamber 308. The ink introduced into the buffer chamber 308 during the suction recovery operation is guided to a waste liquid tank 312. At that time, the cap 103 and the print head 101 are separated, and the pump 311 is driven to guide the ink to the waste liquid tank 312.

[0029] The drive source of pump 311 is pump motor 213, and when pump motor 213 rotates in the forward direction, gears 402 and 404 receive the rotation of the pump motor shaft, causing pump 311 to rotate. When pump motor 213 is driven in the reverse direction, cam pulley 405 rotates as the rotation is transmitted from gear 402 via belt 403. As the drive source, a combination of a DC motor and a rotary encoder or a pulse motor can be used as long as it is capable of rotary motion and position control.

[0030] Fig. 5 is a diagram showing the pressurizing mechanism 304. Fig. 5(a) is a perspective view of the pressurizing mechanism 304, Fig. 5(b) is an exploded view, and Fig. 5(c) is a cross-sectional view taken along line Vc-Vc in Fig. 5(a). The pressurizing mechanism 304 includes a case 501, a fixed plate 502, a tube joint section 503, and a deformable flexible member 303. The tube joint section 503 includes a tube connection section 505 provided for each color of ink, and communicates between the volume change section 303b and a tube connected to the tube joint section 503.

[0031] The flexible member 303 includes a volume change portion 303b which is an ink reservoir portion, and a sealing portion 303a which is a peripheral portion of the volume change portion 303b, and the flexible member 303 is held by sandwiching the sealing portion 303a between the fixed plate 502 and the tube joint portion 503. The flexible member 303 is arranged so that the opening faces upward, and prevents air bubbles from accumulating in the flexible member 303. The fixed plate 502 is joined to the case 501, and the fixed plate 502 and the case 501 are joined by welding or adhesive, etc., to form a closed space 504. A recess is formed in the closed space 504 to accommodate the volume change portion 303b for each color, and the respective recesses are connected to form a single space as the closed space 504.

[0032] The closed space 504 communicates with a pressure connection part 506 provided on the fixed plate 502, and the pressure in the closed space 504 can be adjusted by a pressure pump 801 via a tube (pressurized flow path 314) connected to the pressure connection part 506 and the pressure connection part 506. Arrow B in Fig. 5(c) indicates the flow of ink from the ink tank 107, and arrow C indicates the flow of ink to the recording head 101. Arrow D in Fig. 5(c) indicates the flow of gas from the pressurized flow path 314 toward the closed space 504, and arrow E indicates the flow of gas when the pressurized closed space 504 is returned to atmospheric pressure.

[0033] The pressurizing connection part 506 is connected to the pressurizing pump 801 via the pressurizing flow path 314. The pump 311 is provided so as to be able to change the pressure in the closed space 504, and by driving the pressurizing pump 801, it is possible to send gas to the closed space 504 and pressurize the closed space 504. When the closed space 504 is pressurized, the four volume change parts 303b corresponding to each color are simultaneously pressurized.

[0034] The pressure in the closed space 504 is controlled by controlling the drive of the pump 311 based on the rotation speed, rotation time, etc. of the pump motor 213. Note that, although the control based on the rotation speed and rotation time of the pump 311 has been described as an example, a configuration in which the pressure in the closed space 504 is directly measured by a pressure detection means such as a pressure sensor and the drive / stop of the pump 311 is controlled may also be adopted. Also, although it has been described here that gas is sent to the closed space 504 by the rotation of the pump 311, it is not limited to gas and may be liquid.

[0035] Fig. 6 is a diagram showing the pressure mechanism 304 and the print head 101. Fig. 6(a) shows the pressure mechanism 304 and the print head 101 during a printing operation, and Fig. 6(b) shows the pressure mechanism 304 and the print head 101 during a pressure recovery operation.

[0036] The ink volume inside the recording head 101 varies depending on factors such as gas permeating through the tubes that serve as flow paths and entering the recording head, and differences in the amount of ink filled when the recording head is initially filled. The ink inside the recording head 101 is in a state where atmospheric pressure is applied to the meniscus in the ejection sections 101Ms, 101Ks, and is retained without leaking from the ejection sections 101Ms, 101Ks due to the relationship with the atmospheric pressure applied to the ink liquid surface inside the ink tank 107. Here, as shown in FIG. 6(a), the amounts of ink stored in the recording head 101M and the recording head 101K are different, but the internal pressure in each recording head is the same (P 1 M=P 1 K).

[0037] When the amount of ink in each print head is different, if the pressure inside the print head is increased by supplying a substantially equal amount of ink to each print head using the conventional method, the spaces of different sizes are compressed by a predetermined amount, resulting in a difference in the internal pressure after the pressure is increased. When a difference in the internal pressure of the print head occurs, a difference occurs in the amount of ink discharged when pressure is applied, resulting in a difference in the cleaning effect between the print heads.

[0038] Therefore, the pressurizing mechanism 304 of this embodiment, which is provided so as to be capable of pressurizing the inside of the printhead, supplies an amount of ink corresponding to the amount of ink in the printhead to the four printheads via the volume changing unit 303b, thereby pressurizing the inside of the printheads. In other words, a large amount of ink is supplied from the volume changing unit 303b to a printhead with a small amount of ink, and a small amount of ink is supplied from the volume changing unit 303b to a printhead with a large amount of ink. As a result, the pressure inside each printhead increases after ink flows into the printhead, but the internal pressure in each printhead becomes approximately the same.

[0039] Here, the pressurizing method in the pressurizing mechanism 304 of this embodiment will be described with reference to the drawings. In Fig. 6(a), which shows a printing operation, the refill valve 302 is in an open state, and ink supplied from the ink supply flow path 301 is supplied to the print head 101 via the volume change portion 303b. During this time, the volume of the volume change portion 303b does not change, and the volume change portion 303b becomes part of the flow path.

[0040] In Fig. 6(b), which shows the time of pressurization recovery, the refill valve 302 is in a closed state, and communication between the print head 101 and the ink tank 107 is blocked. In this state, when the pump 311 is driven and air is sent into the closed space 504 of the pressurizing mechanism 304 to increase the pressure, the volume change portion 303b receives the pressure and reduces its volume while supplying ink to the print head 101 (arrow C). In this embodiment, the volume change portion 303b corresponding to each ink is provided (prepared) in the same closed space 504, so that the four volume change portions 303b receive the same pressure in the closed space 504. At this time, ink is supplied to the print head 101 from the volume change portion 303b according to the amount of ink in the print head.

[0041] That is, in a print head in which the amount of ink is small and the proportion of air is large, the air is easily compressed and ink is easily supplied. In contrast, in a print head in which the amount of ink is large and the proportion of air is small, the air is not easily compressed and ink is not easily supplied.

[0042] Therefore, when pressure is applied to each volume change portion 303b by the pressurizing mechanism 304 as in this embodiment, a large amount of ink is supplied to the print head with a small amount of ink, and a small amount of ink is supplied to the print head with a large amount of ink. By pressurizing the inside of the print head in this manner, the pressure inside each print head after pressurization can be made approximately the same. As a result, approximately the same amount of ink can be discharged from each pressurized print head, and the same cleaning effect can be obtained for each print head.

[0043] Here, the pressure inside the recording head during recording is P 1 , volume is V 1 The pressure inside the recording head during the pressure recovery operation is P 2 , volume is V 2 Note that the relational expressions will be explained here for black ink (K) and magenta ink (M), but the same applies for the other colors, cyan (C) and yellow (Y).

[0044] From the relationship PV=k (constant), P 1M×V 1 M=P 2 M×V 2 M.P. 1 K×V 1 K=P 2 K×V 2 K and P 1 M=P 1 K.P. 2 M=P 2 K.P. 1 M <P 2 M.P. 1 K <P 2 It becomes K.

[0045] In this way, according to the present embodiment, the internal pressure of each of the multiple print heads is maintained constant (P 1 M=P 1 K.P. 2 M=P 2 K), pressure can be applied inside the recording head.

[0046] 7 is a perspective view showing a pressurizing pump 801. The pressurizing pump 801 is operated by driving a piston motor 810, which is a stepping motor, and the driving force of the piston motor 810 is decelerated by multiple gears (not shown) and transmitted to a pinion gear 811. The pinion gear 811 meshes with a rack portion 812a of a piston 812, and the rotation of the pinion gear 811 allows the piston 812 to move within a cylinder 813. The position of the piston 812 is determined by a sensor 822 and the number of steps of the piston motor 810. By moving the piston 812, air is let in and out of the cylinder 813, and the pressure within the closed space 504 of the pressurizing mechanism 304 connected to the pressurizing pump 801 can be adjusted.

[0047] An O-ring 825 (shown in FIG. 8(b) described later) is provided on the piston 812. By providing the O-ring 825 between the piston 812 and the inner wall of the cylinder 813, the inside of the cylinder 813 is made into a closed space by the piston 812.

[0048] 8A and 8B are diagrams showing a pressure pump 801 in this embodiment, with FIG. 8A showing a perspective view and FIG. 8B showing a side view. The following description of the pressure pump 801 is not related to the number of recording heads 101, and will be described on the assumption that there is one recording head 101. A cylinder 813 of the pressure pump 801 has an atmosphere communication part 830 on the side of the cylinder that communicates the inside of the cylinder 813 with the atmosphere. The atmosphere communication part 830 is a groove that extends from an edge end part 831 of the cylinder 813 in the X direction, which is the moving direction of the piston 812, and communicates the inside of the cylinder 813 with the atmosphere outside the cylinder 813.

[0049] Since the length of the atmosphere communication portion 830 extending in the X direction from the edge portion 831 of the cylinder 813 is longer than the width dimension of the O-ring 825 in the X direction, when the piston 812 is located at the edge portion 831 of the cylinder 813, the inside of the cylinder 813 communicates with the atmosphere via the atmosphere communication portion 830. When the piston 812 moves in the X direction from the edge portion 831 of the cylinder 813 and passes the X direction terminal portion 814 of the atmosphere communication portion 830, the inside of the cylinder 813 becomes a closed space and communication with the atmosphere outside the cylinder 813 is blocked. In this way, the movement of the piston 812 can switch the inside of the cylinder 813 between a sealed state and an atmosphere communication state.

[0050] Moreover, the piston 812 during standby moves in the X direction from the edge 831 of the cylinder 813, passes the X direction end 814 of the atmosphere communication part 830, and waits at a position where the inside of the cylinder 813 is sealed. The reason is that if the piston 812 waits for a long time while hanging on the atmosphere communication part 830 in order to open the inside of the cylinder to the atmosphere, the O-ring 825 of the piston 812 is deformed by abutting against the atmosphere communication part 830 for a long time, and the deformed part becomes difficult to return to its original state. In a state where the deformation of the O-ring 825 is difficult to return to its original state, the inside of the cylinder 813 cannot be sealed when pressurized, and there is a risk that sufficient pressurization cannot be obtained. Therefore, during standby, the piston 812 waits at a position where it does not hang on the atmosphere communication part 830, so that partial deformation of the O-ring 825 does not occur. Then, when starting the pressurization operation from the standby state, the piston 812 is moved before pressurizing the inside of the cylinder 813, and the pressurization operation is started after the inside of the cylinder 813 is communicated with the atmosphere.

[0051] If the cylinder 813 is sealed during standby, the air in the cylinder 813 may expand due to changes in the outside air temperature. When the volume change section 303b (see FIG. 5) is pressurized by the expansion of the air and the volume decreases, the ink in the volume change section 303b flows into the ink flow path. However, the ink flow path from the pressurizing mechanism 304 (see FIG. 3) to the ink tank 107 side is shorter and has a smaller flow path resistance than the ink flow path from the pressurizing mechanism 304 to the printhead 101 side. Therefore, by opening the refill valve 302 (see FIG. 3) during standby, the ink flowing into the ink flow path flows toward the ink tank 107 side, not toward the printhead 101 side. Therefore, ink does not flow toward the printhead 101, and ink does not leak from the printhead 101.

[0052] The terminal end 814 of the atmosphere communication section 830 may be provided at any position on the side surface of the cylinder 813, but it must be provided at a position that can ensure a volume of air sufficient to deform the volume change section 303b and sufficiently pressurize the inside of the recording head 101 while the cylinder 813 is sealed.

[0053] In this manner, the cylinder 813 of the pressure pump 801 is provided with the atmosphere communication part 830. This makes it possible to provide the liquid ejection device 100 that can suppress an increase in the number of parts and an increase in costs, and can open the area around the flexible part to the atmosphere with a simple configuration.

[0054] (Modification) 9A and 9B are diagrams showing a pressure pump 901 according to a modified example of this embodiment, with Fig. 9A being a perspective view and Fig. 9B being a side view. A cylinder 913 of the pressure pump 901 is provided with an atmosphere communication part 930 that communicates the inside of the cylinder 913 with the atmosphere. The atmosphere communication part 930 is a hole provided in the cylinder 913, and communicates the inside of the cylinder 913 with the atmosphere outside the cylinder 913.

[0055] When the piston 912 is on the edge end 931 side of the atmosphere communication part 930, the inside of the cylinder 813 communicates with the atmosphere through the atmosphere communication part 930. When the piston 912 moves in the X direction from the edge end 931 and passes the atmosphere communication part 930, the inside of the cylinder 913 is cut off from the atmosphere and becomes sealed. During standby, the piston 912 waits at a position that seals the cylinder 913 that is not in contact with the atmosphere communication part 930 for the same reason as in the above-mentioned embodiment, so as to prevent partial deformation of an O-ring (not shown). Then, at the start of the pressurizing operation, before pressurizing the inside of the cylinder 913 with the piston 912, the piston 912 is moved in the -X direction to communicate with the atmosphere and then the pressurizing operation is started.

[0056] In this way, the cylinder 913 is provided with the air communication part 930, which is a hole. This makes it possible to provide the liquid ejection device 100 that can open the area around the flexible part to the atmosphere with a simple configuration while suppressing an increase in the number of parts and an increase in costs.

[0057] The disclosure of this embodiment includes the following configuration.

[0058] (Configuration 1) A recording head that ejects liquid contained therein; A volume change portion formed by a flexible member; a pressure applying mechanism capable of applying pressure to the inside of the recording head by changing the volume of the volume changing portion; a pressure pump that changes the volume of the volume changing unit by sending air to the pressure mechanism; Equipped with the pressure pump is a liquid ejection device that pressurizes air in a cylinder by moving a piston, thereby pressurizing the inside of the recording head through the volume changing unit, The liquid ejection device is characterized in that the cylinder has an atmosphere communication portion on a side of the cylinder that connects the inside of the cylinder with the atmosphere, and the inside of the cylinder can be switched between a state in which it is connected to the atmosphere and a state in which it is sealed, depending on the position of the piston.

[0059] (Configuration 2) 2. The liquid ejection device according to configuration 1, wherein the atmosphere communication portion is a groove extending from an edge of the cylinder in a direction in which the piston moves.

[0060] (Configuration 3) 2. The liquid ejection device according to configuration 1, wherein the air communication portion is a hole provided on a side surface of the cylinder.

[0061] (Configuration 4) An O-ring is provided in the gap between the piston and the cylinder, 4. The liquid ejection device according to any one of configurations 1 to 3, wherein the atmosphere communication portion is provided at a position where it does not come into contact with the piston during standby.

[0062] (Configuration 5) 5. The liquid ejection device according to configuration 4, wherein the cylinder is sealed during standby.

[0063] (Configuration 6) 6. The liquid ejection device according to configuration 5, wherein the pressure pump pressurizes the cylinder after opening it to the atmosphere when starting operation from a standby state.

[0064] (Configuration 7) The liquid contained in the tank is supplied to the recording head through the volume changing section, 7. The liquid ejection device according to configuration 5 or 6, wherein a flow path from the volume change portion to the tank has a lower flow path resistance than a flow path from the volume change portion to the recording head.

[0065] (Configuration 8) 8. The liquid ejection device according to configuration 7, wherein a filter is provided in a flow path from the volume change section to the recording head.

[0066] (Configuration 9) The liquid ejection device according to any one of configurations 1 to 8, wherein the piston has a rack portion.

[0067] (Configuration 10) 10. The liquid ejection device according to any one of configurations 1 to 9, wherein the position of the piston is detected by a sensor. [Explanation of symbols]

[0068] 100 Liquid dispensing device 101 Recording head 107 Ink Tank 304 Pressurizing mechanism 801 Pressure Pump 812 Piston 813 Cylinder 830 Atmospheric communication part 831 Edge 912 Piston 913 Cylinder 930 Atmospheric communication part 931 Edge

Claims

1. A recording head that ejects liquid contained therein; A volume change portion formed by a flexible member; a pressure applying mechanism capable of applying pressure to the inside of the recording head by changing the volume of the volume changing portion; a pressure pump that changes the volume of the volume changing unit by sending air to the pressure mechanism; Equipped with the pressure pump is a liquid ejection device that pressurizes air in a cylinder by moving a piston, thereby pressurizing the inside of the recording head through the volume changing unit, The liquid ejection device is characterized in that the cylinder has an atmosphere communication portion on a side of the cylinder that connects the inside of the cylinder to the atmosphere, and the inside of the cylinder can be switched between a state in which it is connected to the atmosphere and a state in which it is sealed, depending on the position of the piston.

2. 2. The liquid ejection device according to claim 1, wherein the atmosphere communication portion is a groove extending from an edge of the cylinder in a direction in which the piston moves.

3. 2. The liquid ejection device according to claim 1, wherein the air communication portion is a hole provided in a side surface of the cylinder.

4. An O-ring is provided in the gap between the piston and the cylinder, The liquid ejection device according to claim 1, wherein the atmosphere communication portion is provided at a position where it does not come into contact with the piston during standby.

5. 5. The liquid ejection device according to claim 4, wherein the cylinder is sealed during standby.

6. 6. The liquid ejection device according to claim 5, wherein the pressure pump pressurizes the cylinder after opening it to the atmosphere when starting operation from a standby state.

7. The liquid contained in the tank is supplied to the recording head through the volume changing section, 6. The liquid ejection device according to claim 5, wherein a flow path resistance from the volume change portion to the tank is lower than a flow path resistance from the volume change portion to the recording head.

8. 8. The liquid ejection apparatus according to claim 7, further comprising a filter provided in a flow path from the volume change portion to the recording head.

9. The liquid ejection device according to claim 1 , wherein the piston has a rack portion.

10. 2. The liquid ejection device according to claim 1, wherein the position of the piston is detected by a sensor.

Images