JP2025079068A - liquid discharge device - Google Patents

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

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

Patent Document 1 discloses that the flexible portion 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 portion in order to control the applied pressure. One method of adjustment is to connect the flexible portion 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 portion 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.

JP 2010-260182 A

However, the mechanism for opening to the atmosphere in Patent Document 1 has a complex configuration in that when the valve body is pushed down and the opening separates from the seal, the space is connected to the atmosphere via the opening.

There is also a method of adjusting the pressure by installing a sensor that detects the pressure without opening it to the atmosphere, but this raises concerns about the increased number of parts and costs.

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.

The liquid ejection device of the present invention is characterized in that it comprises a recording head that 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 that changes the volume of the volume change section by sending air to the pressurizing mechanism, and the pressurizing pump pressurizes the air in 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 the side of the cylinder that communicates the inside of the cylinder with 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.

The present invention provides a liquid ejection device that can open the area around the flexible portion to the atmosphere with a simple configuration.

FIG. 1 illustrates a liquid ejection device. FIG. 2 is a block diagram showing an example of the configuration of a control system of the printing apparatus. FIG. 2 is a schematic diagram showing the configuration of an ink flow path system. FIG. 2 is a detailed diagram of the configuration of an ink flow path system. FIG. FIG. 2 is a diagram showing a pressure mechanism and a recording head. FIG. FIG. FIG. 13 is a diagram showing a pressure pump according to a modified example.

The following describes an embodiment of the present invention with reference to the drawings.

Figure 1 shows a liquid ejection device (hereinafter also referred to as a recording device) 100 to which this 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 this 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 that is recorded 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 of the recording medium P (direction of arrow A). 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.

The print head 101 is provided with ejection energy generating elements such as electrothermal conversion elements (heaters) and piezoelectric elements, and ejects ink from multiple ejection orifices. For example, when electrothermal conversion elements are used as ejection energy generating elements, ink is foamed by heat generation, and the foaming energy is used to eject ink from the ejection orifices. The multiple ejection orifices are arranged in a direction intersecting the conveying direction of the print medium P (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. In addition, the print head 101 is positioned at a predetermined printing position during printing operation.

The recording device 100 is provided with a recovery unit 104 that performs a process (hereinafter, a recovery process) to maintain or recover 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 port formation surface (hereinafter, also referred to as the ejection port formation surface) of the recording head 101, facing the ejection ports 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 port formation surface, a wiper holding member that holds the wiper, and an ink removal member that removes ink attached to the wiper.

The recording medium P is supplied from a supply unit 105 and transported in a transport direction (arrow A direction) by a transport mechanism 106 built into the recording device 100. The transport mechanism 106 is equipped with 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 a roller 106c that applies 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 a transport roller, or may be an integrated transport unit.

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

The recording device 100 is provided with ink tanks 107 (107K, 107C, 107M, 107Y) that supply ink to the recording head 101. In addition, the recording device 100 is provided with pumps and motors that supply ink to the recording head 101 and perform recovery processing (hereinafter also referred to as recovery operations).

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

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 drive of the capping motor 212 and the head lift motor 210 via the output port 208 and the motor drive unit 209. This moves each recording head (101Y, 101M, 101C, 101K) away from the corresponding cap 103 and moves it 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.

The CPU 202 drives and controls a roll motor (not shown) that feeds the recording medium P and a transport motor 106b that transports the recording medium P at a constant speed via an output port 208 and a motor drive unit 209, thereby transporting the recording medium P in the transport direction. The timing (printing timing) of ejecting ink onto the recording medium P transported 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).

The CPU 202 sequentially reads out the recording data corresponding to each ink color from the image memory 204 in synchronization with the transport 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.

Figure 3 is a schematic diagram showing the configuration of the ink flow path system in this embodiment, and Figure 4 is a detailed diagram of the configuration of the ink flow path system. Note that while Figure 3 shows an ink flow path system for one color of ink, 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.

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 pressure mechanism 304 including a flexible member 303, and a filter 305. The ink tank 107 has an air opening 107a at the top, and when a flow of ink toward the ink tank 107 is generated, air is released from the air opening 107a, allowing the ink to flow into the ink tank 107 without resistance.

The recording head 101 is equipped with the above-mentioned ejection section, a storage chamber that stores the ink to be supplied to the ejection section and stores air above it, and a sensor 306 that detects the liquid level. The liquid level in the recording head 101, i.e., the amount of stored ink, is managed by the electrode-type sensor 306. The cap 103 is connected to the buffer chamber 308 via a filter 307 and a recovery valve 316. The cap 103 is provided so that it can abut against the ejection port forming surface, and moves to an abutment 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 inside the cap to the atmosphere in order to alleviate sudden pressure fluctuations that occur in the space inside the cap due to the contact and separation operations.

The buffer chamber 308 functions to transmit or store pressure for transferring fluid between the recording head 101 and the cap 103 during the pressurized recovery operation and the suction recovery operation, which are the recovery operations described below. The buffer chamber 308 also functions to receive ink discharged from the recording head 101 and the cap 103 during the pressurized recovery operation and the suction recovery operation. The buffer chamber 308 has an openable and closable buffer valve 310 at its top 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 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 inside the buffer chamber 308.

In this embodiment, a tube pump capable of blocking the flow path is used as pump 311, but this is not limited to this, and any pump capable of freely generating pressure may be used.

The 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, and a transfer operation to a waste liquid tank. Depending on the operation being performed, the refill valve 302, the air release valve 309, the buffer valve 310, and the recovery valve 316 are appropriately opened and closed, and the cap 103 is brought into contact with or separated from the ejection port formation surface.

During a recording operation, the recording head 101 moves to a position further below the position shown in FIG. 1, and at least the refill valve 302 is open.

During the suction recovery operation, the atmospheric release valve 309, the buffer valve 310, and the recovery valve 316 are all closed, and the cap 103 is in contact with the ejection port formation surface of the recording head 101. The pump 311 is then driven in reverse to reduce the pressure inside the buffer chamber 308, and when the pressure sensor 317 detects that the buffer chamber 308 has reached a predetermined negative pressure, the recovery valve 316 is opened. The cap 103 is then depressurized to suck ink from the recording 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 led to the waste liquid tank 312. At that time, the cap 103 and the recording head 101 are separated and the pump 311 is driven to lead the ink to the waste liquid tank 312.

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

Figure 5 shows the pressure mechanism 304. Figure 5(a) is a perspective view of the pressure mechanism 304, Figure 5(b) is an exploded view, and Figure 5(c) is a cross-sectional view taken along line Vc-Vc in Figure 5(a). The pressure mechanism 304 comprises a case 501, a fixed plate 502, a tube joint section 503, and a deformable flexible member 303. The tube joint section 503 comprises a tube connection section 505 provided for each color of ink, and connects the volume change section 303b to a tube connected to the tube joint section 503.

The flexible member 303 has 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. The sealing portion 303a is sandwiched between the fixed plate 502 and the tube joint portion 503 to hold the flexible member 303. The flexible member 303 is arranged so that the opening faces upward, preventing 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. The closed space 504 has recesses formed therein to accommodate the volume change portions 303b for each color, and the recesses are connected to each other to form a single space as the closed space 504.

The closed space 504 is connected to a pressure connection 506 provided on the fixed plate 502, and the pressure in the closed space 504 can be adjusted by a pressure pump 801 via the pressure connection 506 from a tube (pressurized flow path 314) connected to the pressure connection 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.

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, gas can be sent to the closed space 504, thereby pressurizing the closed space 504. When the closed space 504 is pressurized, the four volume change parts 303b corresponding to each color are simultaneously pressurized.

The pressure in the closed space 504 is controlled by controlling the drive of the pump 311 through the rotation speed and rotation time of the pump motor 213. Note that, although the control through the rotation speed and rotation time of the pump 311 has been described as an example, the pressure in the closed space 504 may be directly measured by a pressure detection means such as a pressure sensor, and the drive and stop of the pump 311 may be controlled. 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 liquid may also be sent.

Figure 6 shows the pressure mechanism 304 and the recording head 101. Figure 6(a) shows the pressure mechanism 304 and the recording head 101 during a recording operation, and Figure 6(b) shows the pressure mechanism 304 and the recording head 101 during a pressure recovery operation.

The ink volume in the print head 101 varies depending on factors such as the gas permeating through the tubes that serve as the flow paths and entering the print head, and the difference in the amount of ink filled when the print head is initially filled. The ink in the print 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 in the ink tank 107. Here, as shown in Fig. 6A, the ink volumes stored in the print head 101M and print head 101K are different, but the internal pressure in each print head is the same ( _P1M = _P1K ).

When the amount of ink in each print head is different in this way, if the pressure inside the print head is increased by supplying an approximately equal amount of ink to each print head using conventional methods, the spaces of different sizes are compressed by a certain amount, resulting in a difference in the internal pressure after the pressure is increased. When there is a difference in the internal pressure of the print head, there is a difference in the amount of ink discharged when pressure is applied, resulting in a difference in the cleaning effect between each print head.

In this embodiment, the pressurizing mechanism 304 is provided so as to be capable of pressurizing the inside of the print head, and pressurizes the inside of the print head by supplying an amount of ink corresponding to the amount of ink in the print head to the four print heads via the volume change unit 303b. In other words, a large amount of ink is supplied from the volume change unit 303b to a print head with a small amount of ink, and a small amount of ink is supplied from the volume change unit 303b to a print head with a large amount of ink. As a result, the pressure inside each print head increases after the ink flows into the print head, but the internal pressure in each print head is approximately the same.

The pressurizing method in the pressurizing mechanism 304 of this embodiment will now 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 section 303b. During this time, the volume of the volume change section 303b does not change, and the volume change section 303b becomes part of the flow path.

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

In other words, in a print head where 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 where 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.

Therefore, when pressure is applied to each volume change portion 303b by the pressure 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 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.

Here, the pressure inside the print head during printing _{is P1} , the volume is _V1 , and the pressure inside the print head during pressure recovery is _P2 , and the volume is _V2 . Note that although the relational expressions will be explained here for black ink (K) and magenta ink (M), the same applies for the other colors, cyan (C) and yellow (Y).

Due to the relationship PV=k (constant), _P1M × _V1M = _P2M × _V2M , _P1K × _V1K = _P2K × _V2K , and _P1M = _P1K , _P2M = _P2K , _P1M < _P2M , _P1K < _P2K .

In this way, according to this embodiment, it is possible to apply pressure inside the print heads while maintaining a state in which there is no difference in the internal pressure among the plurality of print heads (P ₁ M=P ₁ K, P ₂ M=P ₂ K).

Figure 7 is a perspective view showing the 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.

The piston 812 is provided with an O-ring 825 (shown in FIG. 8(b) described later). By providing the O-ring 825 between the piston 812 and the inner wall of the cylinder 813, the piston 812 makes the inside of the cylinder 813 into a closed space.

Figure 8 shows a pressure pump 801 in this embodiment, with Figure 8(a) showing a perspective view and Figure 8(b) showing a side view. Note that the following explanation of the pressure pump 801 is not related to the number of recording heads 101, and will be explained assuming that there is only one recording head 101. The cylinder 813 of the pressure pump 801 has an atmosphere communication part 830 on the side of the cylinder that connects the inside of the cylinder 813 to the atmosphere. The atmosphere communication part 830 is a groove that extends from the edge end part 831 of the cylinder 813 in the X direction, which is the movement direction of the piston 812, and connects the inside of the cylinder 813 to the atmosphere outside the cylinder 813.

The length of the atmosphere communication part 830 extending in the X direction from the edge end 831 of the cylinder 813 is longer than the width dimension of the O-ring 825 in the X direction, so when the piston 812 is located at the edge end 831 of the cylinder 813, the inside of the cylinder 813 communicates with the atmosphere via the atmosphere communication part 830. When the piston 812 moves in the X direction from the edge end 831 of the cylinder 813 and passes the X direction terminal end 814 of the atmosphere communication part 830, the inside of the cylinder 813 becomes a closed space and communication with the atmosphere outside the cylinder 813 is cut off. In this way, the movement of the piston 812 can switch between a sealed state inside the cylinder 813 and a state communicating with the atmosphere.

In addition, 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 for this 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 will be deformed by abutting against the atmosphere communication part 830 for a long time, and the deformed part will be 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 will not 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 inside of the cylinder 813 is connected to the atmosphere before starting the pressurization operation.

When 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 lower flow path resistance than the ink flow path from the pressurizing mechanism 304 (see FIG. 3) to the print head 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 the print head 101 side. Therefore, ink does not flow toward the print head 101 and ink does not leak from the print head 101.

The end 814 of the air communication section 830 may be located anywhere on the side of the cylinder 813, but it must be located in a position that ensures 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.

In this way, the cylinder 813 of the pressure pump 801 is provided with an atmosphere communication part 830. This makes it possible to provide a 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.

(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 includes 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.

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. Also, 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, for the same reason as in the above-mentioned embodiment, the piston 912 waits in a position that seals the cylinder 913 that is not in contact with the atmosphere communication part 930, so as to prevent partial deformation of an O-ring (not shown). Then, when the pressurization operation starts, 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 pressurization operation starts.

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

The disclosure of this embodiment includes the following configuration:

(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 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.

(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.

(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.

(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.

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

(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.

(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.

(Configuration 8)
8. The liquid ejection apparatus according to configuration 7, wherein a filter is provided in a flow path from the volume change portion to the recording head.

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

(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.

REFERENCE SIGNS LIST 100 Liquid ejection device 101 Recording head 107 Ink tank 304 Pressurizing mechanism 801 Pressurizing pump 812 Piston 813 Cylinder 830 Atmosphere communication part 831 Edge part 912 Piston 913 Cylinder 930 Atmosphere communication part 931 Edge part

Claims (10)

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. The liquid ejection device according to claim 1, characterized in that the atmosphere communication part is a groove extending from the edge of the cylinder in the direction of movement of the piston. The liquid ejection device according to claim 1, characterized in that the atmosphere communication part is a hole provided on the side of the cylinder. 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. The liquid ejection device according to claim 4, characterized in that the cylinder is sealed during standby. The liquid ejection device according to claim 5, characterized in that when the pressurizing pump starts operation from a standby state, it pressurizes the cylinder after opening it to the atmosphere. 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. The liquid ejection device according to claim 7, characterized in that a filter is provided in the flow path from the volume change section to the recording head. The liquid ejection device according to claim 1, characterized in that the piston has a rack portion. The liquid ejection device according to claim 1, characterized in that the position of the piston is detected by a sensor.

Images