JP2005246742A - Liquid tank, head cartridge, and liquid ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize a meniscus position of a liquid in a liquid ejection nozzle by suppressing the rapid supply of the liquid to a liquid ejection head from a liquid tank, in a head cartridge for ejecting the liquid, stored in the liquid tank, from the liquid ejection nozzle of the liquid ejection head. <P>SOLUTION: This head cartridge 1 for supplying and ejecting ink 3 in an ink tank 2 to a print head 4 is equipped with an ink supply pipe 24 for supplying the ink 3 in the ink tank 2 to the print head 4, a first valve 26 for opening/closing a liquid channel of the ink supply pipe 24, and an outside-air communication hole 21 for taking in air, equivalent to the quantity of the reduced ink 3, into the ink tank 2 when the quantity of the ink 3 is reduced by supplying the ink 3 in the ink tank 2 to the print head 4. A second valve 29, which is provided between an opening/closing port of the first valve 26 and the communication hole 21, is opened after the opening of the first valve 26. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid tank and a head cartridge including a liquid supply device that supplies a predetermined liquid stored in the liquid tank to a liquid discharge head, and a liquid discharge device. Specifically, the liquid supply system includes two valves. Thus, the present invention relates to a head cartridge and a liquid ejection device that suppress abrupt supply of liquid from a liquid tank to a liquid ejection head and stabilize the meniscus position of the liquid in the liquid ejection nozzle.

  2. Description of the Related Art Conventionally, in an ink jet printer, as a head cartridge that forms an image by ejecting ink onto a recording paper, an ink tank that stores the ink, a print head that ejects ink droplets from an ink ejection nozzle formed on a nozzle member, and an ink Some have an ink supply device that supplies ink in the tank to the print head. The ink supply device for the head cartridge has an ink supply pipe for supplying ink in the ink tank to the ink discharge head, and a valve for adjusting the amount of ink flowing down through the ink supply pipe. Ink was supplied into the print head by controlling opening and closing. In a head cartridge equipped with such an ink supply device, it is considered important to stably eject ink droplets from the ink ejection nozzles of the print head in order to stabilize the image quality of the print image.

As an ink supply device for such a problem, an ink supply pipe connected to an ink tank in which ink is accommodated so that the ink in the ink tank can flow, and an ink flow path of the ink supply pipe are opened and closed. The liquid passage is opened by the pressure drop in the print head that is generated when ink is ejected from the ink ejection nozzle of the print head. A moving valve, an external air communication hole that takes in air corresponding to the reduced amount when the amount of ink in the ink tank supplied to the print head decreases, and the pressure of the ink in the print head Pressure fluctuation adjusting means for controlling the pressure fluctuation in the ink chamber to be gentle until the valve is opened and closed There was. In this case, until the new ink is supplied into the print head, the pressure fluctuation adjusting means prevents the ink meniscus position in each ink discharge nozzle from fluctuating rapidly (for example, patents). (See Reference 1.)
JP 2003-127414 A

  However, in the ink supply device described in Patent Document 1, the ink meniscus position in each ink discharge nozzle does not change rapidly until new ink is supplied into the print head. However, after the valve is opened, the ink is not configured to be suppressed from flowing in abruptly. Therefore, after the valve is opened, the ink rapidly flows into the print head, and the meniscus position of the ink in the ink discharge nozzle may fluctuate and become unstable. In this case, ink droplets are not stably ejected from each ink ejection nozzle, and the quality of the printed image may be deteriorated.

  Accordingly, the present invention addresses such problems, suppresses the rapid supply of liquid from the liquid tank to the liquid discharge head, and stabilizes the meniscus position of the liquid in the liquid discharge nozzle and the liquid It is an object of the present invention to provide a discharge device and a liquid tank used for them.

  In order to achieve the above object, the liquid tank according to the present invention has a predetermined liquid stored therein, and when the amount of the liquid is reduced by supplying the liquid to the outside, the outside air communication for taking in air corresponding to the decreased amount is provided. A liquid tank having a hole, wherein the outside air communication hole is provided with a duckbill type check valve.

  With such a configuration, when the liquid in the liquid tank is supplied to the outside and the amount is reduced, the air corresponding to the reduced amount is taken in from the opening of the outside air communication hole provided with the duckbill type check valve. .

  A head cartridge according to the present invention includes a liquid tank that contains a predetermined liquid therein, a liquid discharge head that supplies liquid from the liquid tank and discharges the predetermined liquid from a liquid discharge nozzle formed on a nozzle member, The liquid tank is energized to close the liquid flow path of a liquid supply pipe that supplies the liquid in the liquid discharge head to the liquid discharge head, and is generated when the liquid is discharged from the liquid discharge nozzle of the liquid discharge head. A first valve that opens the liquid flow path due to a pressure drop in the liquid discharge head, and air corresponding to the decrease when the amount of liquid in the liquid tank is reduced by supplying the liquid in the liquid tank to the liquid discharge head. A head cartridge comprising: a liquid supply device having an outside air communication hole that is taken into the liquid tank; and an opening / closing port of the first valve and the outside air communication hole A second valve provided between, the second valve is one which is adapted to open with a delay in the opening of the first valve.

  With such a configuration, the first valve is opened due to a pressure drop in the liquid discharge head to connect the liquid flow path of the liquid supply pipe, and the second valve is opened after the opening of the first valve. Then, air corresponding to the amount of liquid reduced by supplying the liquid from the liquid tank to the liquid discharge head is taken in from the outside air communication hole into the liquid tank with a delay.

  Furthermore, a liquid discharge apparatus according to the present invention includes a liquid tank that contains a predetermined liquid therein, a liquid discharge head that discharges the predetermined liquid from a liquid discharge nozzle that is supplied with the liquid from the liquid tank and formed in the nozzle member, and Generated when the liquid in the liquid tank is energized to close the liquid flow path of the liquid supply pipe that supplies the liquid discharge head and the liquid is discharged from the liquid discharge nozzle of the liquid discharge head. A first valve that opens the liquid flow path due to a pressure drop in the liquid discharge head, and an air corresponding to the decrease when the amount of liquid in the liquid tank is reduced by supplying the liquid discharge head to the liquid discharge head. A head cartridge provided with a liquid supply device having an outside air communication hole for taking the liquid into the liquid tank is detachably stored in the main body of the device, and the head cartridge In the liquid discharge apparatus for discharging liquid from the liquid discharge head, a second valve is provided between the opening and closing port of the first valve of the head cartridge and the outside air communication hole, and the second valve is the first valve. The valve is opened after the opening of the valve.

  With such a configuration, the first valve is opened due to a pressure drop in the liquid discharge head to connect the liquid flow path of the liquid supply pipe, and the second valve is opened after the opening of the first valve. Then, air corresponding to the amount of liquid reduced by supplying the liquid from the liquid tank to the liquid discharge head is taken in from the outside air communication hole into the liquid tank with a delay.

  According to the liquid tank of the first aspect, when the liquid in the liquid tank is supplied to the outside and the amount is reduced, the air corresponding to the reduced amount is supplied to the outside air communication hole provided with the duckbill type check valve. Since it is taken in from the opening, the pressure inside the liquid tank is stabilized without changing abruptly. In addition, the duckbill type check valve opens when the pressure difference is in the forward direction and allows the fluid to flow freely. It is possible to prevent the liquid from being blown out from the outside air communication port and becoming dirty.

  According to the head cartridge of the second aspect, the first valve that opens and closes the liquid flow path of the liquid supply pipe, and the second valve between the opening and closing port of the first valve and the outside air communication hole. Since the second valve is opened after the opening of the first valve, air corresponding to the reduced amount of liquid supplied from the liquid tank to the liquid discharge head is discharged to the outside air. It is taken in from the communication hole into the liquid tank with a delay. Thereby, it is possible to suppress the rapid supply of liquid from the liquid tank to the liquid discharge head, and to prevent the dynamic negative pressure of the liquid in the liquid discharge head from changing rapidly. Accordingly, the liquid meniscus position in the liquid discharge nozzle is stabilized, and thus the liquid droplets can be stably discharged.

  Further, according to the invention of claim 3, the first valve is provided with the liquid by providing pressure fluctuation adjusting means on the downstream side of the opening / closing port of the first valve in the middle of the liquid supply pipe. The pressure fluctuation inside the liquid ejection head from the time when the liquid is supplied from the liquid tank to the liquid ejection head after the flow path is opened until the first valve closes the liquid flow path is moderated. Thus, the liquid flow path is opened. As a result, rapid liquid supply from the liquid tank to the liquid discharge head is suppressed, and the liquid meniscus position slightly recedes. Accordingly, the liquid meniscus position in the liquid discharge nozzle is stabilized, so that the liquid can be stably discharged.

  According to the fourth aspect of the present invention, the liquid tank can be exchanged by making the liquid tank detachable from the liquid supply pipe.

  According to the fifth aspect of the present invention, the second valve is provided in the outside air communication hole, so that the amount of air taken into the liquid tank from the outside can be adjusted. At this time, since the second valve is opened after the opening of the first valve, the liquid in the liquid tank is reduced after the liquid is supplied from the liquid tank into the liquid chamber. The air corresponding to the amount is taken into the liquid tank from the outside air communication hole.

  According to a sixth aspect of the present invention, the second valve is provided in the middle of the liquid flow path of the liquid supply pipe, so that rapid liquid supply from the liquid tank to the liquid discharge head is performed. It is possible to suppress the dynamic negative pressure of the liquid in the liquid discharge head from abruptly changing. Accordingly, the meniscus position of the liquid in the liquid discharge nozzle becomes stable, and the droplets can be discharged stably. Further, the mounting position of the second valve can be freely designed.

  According to the invention of claim 7, the second valve is a duckbill type check valve, so that it opens at the time of forward differential pressure and allows fluid to flow freely. With the pressure, the back flow of the fluid can be suppressed while being closed. Further, if a duckbill type check valve is attached to the external air communication hole of the removable liquid tank, it is possible to prevent the liquid from being blown out from the external air communication port and being contaminated during handling.

  According to the liquid ejection apparatus of the eighth aspect, the first valve that opens and closes the liquid flow path of the liquid supply pipe provided in the head cartridge, and the opening and closing port of the first valve and the outside air communication hole are provided. A second valve is provided in between, and this second valve opens after the opening of the first valve. The air corresponding to the amount is taken into the liquid tank from the outside air communication hole with a delay. Thereby, it is possible to suppress the rapid supply of liquid from the liquid tank to the liquid discharge head, and to prevent the dynamic negative pressure of the liquid in the liquid discharge head from changing rapidly. Therefore, the liquid meniscus position in the liquid discharge nozzle is stabilized, so that the liquid droplets can be stably discharged, and the liquid discharge performance can be improved.

  According to the ninth aspect of the present invention, the first valve is provided by providing pressure fluctuation adjusting means on the downstream side of the opening and closing port of the first valve in the middle of the liquid supply pipe of the head cartridge. Changes in pressure inside the liquid discharge head from when the liquid flow path is opened and liquid is supplied from the liquid tank to the liquid discharge head until the first valve closes the liquid flow path. The liquid flow path is opened so that the pressure becomes gentle. As a result, rapid liquid supply from the liquid tank to the liquid discharge head is suppressed, and the liquid meniscus position slightly recedes. Therefore, since the meniscus position of the liquid in the liquid discharge nozzle is stabilized, the liquid can be stably discharged, and the liquid discharge performance can be improved.

  Here, according to the invention of claim 10, the liquid tank can be exchanged by making the liquid tank detachable from the liquid supply pipe.

  Moreover, according to the invention which concerns on Claim 11, the quantity of the air taken in can be adjusted. At this time, since the second valve is opened after the opening of the first valve, the liquid in the liquid tank is reduced after the liquid is supplied from the liquid tank into the liquid chamber. The air corresponding to the amount is taken into the liquid tank from the outside air communication hole.

  Furthermore, according to the twelfth aspect of the present invention, the second valve is provided in the middle of the liquid flow path of the liquid supply pipe, so that rapid liquid supply from the liquid tank to the liquid discharge head is performed. It is possible to suppress the dynamic negative pressure of the liquid in the liquid discharge head from abruptly changing. Therefore, the meniscus position of the liquid in the liquid discharge nozzle becomes stable, and the liquid droplet can be stably discharged, and the liquid discharge performance can be improved. Further, the mounting position of the second valve can be freely designed.

  According to the thirteenth aspect of the present invention, the second valve is a duckbill type check valve, so that it opens when the differential pressure is in the forward direction and allows fluid to flow freely. With the pressure, the back flow of the fluid can be suppressed while being closed. Further, if a duckbill type check valve is attached to the external air communication hole of the removable liquid tank, it is possible to prevent the liquid from being blown out from the external air communication port and being contaminated during handling.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing an embodiment of an ink jet printer as an example of a liquid ejection apparatus according to the present invention. The ink jet printer 100 forms an image by ejecting ink droplets on a recording paper, and includes a head cartridge 1, a printer main body 101, and a recording paper tray 102.

  A printer main body 101 shown in FIG. 1 includes a transport mechanism for transporting recording paper stored in a recording paper tray 102, and a control device for appropriately printing on recording paper as an ejection target. The recording paper tray 102 is detachably attached to a tray insertion opening 103 provided in the lower part of the front surface. The tray insertion port 103 also serves as a recording paper discharge port, so that the recording paper printed by the printer main body 101 is discharged from a discharge receiving portion 102 a on the upper surface of the recording paper tray 102. Yes. In addition, a display panel (display unit) 104 is provided at the upper front of the printer main body 101 so as to display the overall operation state of the ink jet printer 100.

  An upper lid 105 is attached to the upper surface side of the printer main body 101 so as to be openable and closable. When the upper lid 105 is opened, a housing portion 106 for accommodating the head cartridge 1 is formed on the upper surface side of the printer main body 101. ing. The head cartridge 1 is stored in the storage section 106 of the printer main body 101 as indicated by an arrow Z and is held in a detachable state. The head cartridge 1 has a casing that is elongated in the width direction of the printer main body 101, that is, in the width direction of the recording paper. An image is formed by discharging onto paper, and the ink discharge surface on the lower surface is covered with a head cap 107.

  FIG. 2 is a schematic view showing an embodiment of a head cartridge according to the present invention. This head cartridge 1 is configured to eject ink droplets onto a recording paper as an ejection target in the ink jet printer 100 shown in FIG. 1, and as shown in FIG. 2, an ink tank 2 and a print head 4 and an ink supply device 5.

  The ink tank 2 is a box-like container that contains ink (predetermined liquid) 3 therein, and the four ink tanks 2 (2y, 2m, 2c, 2k) is loaded, and each ink tank 2 contains ink of four colors Y, M, C, and K. As shown in FIG. 2, an outside air communication hole 21 is formed at the center of the upper surface of the ink tank 2. The outside air communication hole 21 serves as a vent for taking in air from the outside to the inside of the ink tank 2, and the ink 3 is supplied from the inside of the ink tank 2 to the print head 4 to be described later to reduce the amount of the ink 3. When this occurs, air corresponding to the reduced amount of the ink 3 is taken into the ink tank 2. Inside the ink tank 2, an air introduction pipe 22 connected to the outside air communication hole 21 is provided, and air taken in from the outside air communication hole 21 is introduced into the ink tank 2. ing.

  Near the center of the air introduction tube 22, for example, a buffer portion 23 having a rhombus cross section is provided. The buffer unit 23 is a space for temporarily storing ink stored in the ink tank 2 when it flows back to the air introduction tube 22, and the ink 3 that has flowed back from the outside air communication hole 21. The volume does not flow out. Specifically, at normal temperature and normal pressure, the ink 3 is not stored in the buffer portion 23 of the ink tank 2 as shown in FIG. On the other hand, for example, when the external pressure drops or the external temperature rises, although not shown, the air accumulated in the upper portion of the ink tank 2 expands and the ink 3 is pushed out to the air introduction tube 22 side. . At this time, the pushed out ink 3 is temporarily stored in the buffer unit 23, so that the ink 3 does not flow out from the outside air communication hole 21.

  The ink 3 stored in the ink tank 2 is supplied to the print head 4 by an ink supply device 5 described later. The print head 4 serves as a liquid discharge head for finely pulverizing the ink 3 supplied from the ink tank 2 and discharges it, as shown in FIG. A large number of ink discharge nozzles 7 are formed in the member 6 in a row. An ink supply port 8 is provided at the center of the upper surface of the print head 4. Here, for example, a full-line type print head 4 in which the nozzle member 6 is formed to be long across the width of one side of A4 size recording paper is shown.

  4 is an enlarged cross-sectional view of a portion P of the print head 4 shown in FIG. As shown in FIG. 4, the print head 4 includes a substrate member 10, a barrier layer 11, and a nozzle member 6. The ink 3 in the ink pressurizing chamber 12 is heated by a heater 13 to generate bubbles. The ink is generated and discharged as ink droplets 14 by the energy generated when the bubbles are generated.

  The substrate member 10 is formed by depositing a heater 13 on its lower surface, and the heater 13 is driven and controlled by a logic IC, a driver transistor, etc. (not shown). A barrier layer 11 is formed on the lower surface of the substrate member 10. The barrier layer 11 is made of, for example, an exposure-curing dry film resist, and is laminated on the entire surface of the substrate member 10 on which the heater 13 is formed, and then unnecessary portions are removed by a photolithography process. Thus, it is formed in a predetermined shape. Thereby, the barrier layer 11 is formed so as to surround the peripheral portion of each heater 13 in a substantially concave shape. A nozzle member 6 shown in FIG. 3 is bonded to the lower surface of the barrier layer 11. The nozzle member 6 is a sheet-like member on which nozzles 7 for ejecting ink droplets 14 are formed. As shown in FIG. 3, a large number of ink ejection nozzles 7 are arranged in a substantially straight line. The nozzle member 6 is formed by, for example, nickel electroforming, and is bonded to the lower surface of the barrier layer 11 so that the position of each ink discharge nozzle 7 matches the position of the heater 13 as shown in FIG. ing.

  Thus, the lower surface of the substrate member 10 becomes the upper surface of the ink pressurizing chamber 12, the portion surrounding the heater 13 of the barrier layer 11 becomes the side surface of the ink pressurizing chamber 12, and the nozzle member 6 becomes the lower surface of the ink pressurizing chamber 12. Therefore, the ink pressurizing chamber 12 is configured to surround the heater 13, and the ink 3 is replenished from the opening on the right side in FIG. Therefore, as shown in FIG. 3, the ink 3 flowing down from the ink tank 2 is supplied into the print head 4 through a valve device 20 described later, and as shown in FIG. The pressure chamber 12 is replenished. Then, by heating the heater 13 to generate bubbles, the ink 3 in the ink pressurizing chamber 12 can be ejected from each nozzle 7 as ink droplets 14 (see FIG. 3).

  As shown in FIG. 2, the ink supply device 5 of the head cartridge 1 includes an ink supply pipe 24 and a first valve 26. The ink supply pipe 24 serves as a flow path for supplying the ink 3 flowing down from the ink tank 2 to the print head 4, and is disposed on the bottom surface side of the ink tank 2.

  A valve device 20 having a first valve 26 is provided on the downstream side of the ink supply pipe 24. The valve device 20 controls the supply of the ink 3 flowing down from the ink tank 2, and includes an ink chamber 25, a first valve 26, and a spring (biasing member) 27.

  The ink chamber 25 is a liquid chamber connected to the ink tank 2 so that the ink 3 in the ink tank 2 flows down. For example, the ink chamber 25 is a box-shaped body having a substantially rectangular parallelepiped shape. The valve 26 and the spring 27 are disposed, and an ink delivery pipe 28 for delivering the ink 3 is provided below the valve 26 and the spring 27. The ink delivery tube 28 is a part of a flow path for supplying the ink 3 in the ink chamber 25 to the print head 4, and is connected to the ink supply port 8 on the upper surface of the print head 4. The first valve 26 in the ink chamber 25 opens and closes the liquid flow path between the ink tank 2 side and the valve device 20 side, and the liquid between the ink tank 2 and the ink chamber 25 is opened. The ink is energized so as to close the flow path, and the ink in the print head 4 and the ink chamber 25 is lowered when the ink droplet 14 is ejected from the ink ejection nozzle 7 of the print head 4. The liquid flow path between the tank 2 and the ink chamber 25 is moved so as to communicate with each other. That is, a compression coil spring 27 is attached so as to connect the lower surface side of the first valve 26 and the bottom surface of the ink chamber 25, and the first valve 26 is biased to the closed side by the spring 27. It is supposed to be.

  As a result, as shown in FIG. 2, in a steady state, the first valve 26 is pressed against the upper surface of the ink chamber 25 by the urging force of the spring 27, and between the ink tank 2 side and the valve device 20 side. The ink 3 in the ink tank 2 is prevented from flowing down. On the other hand, as shown in FIG. 3, when the ink droplets 14 are ejected from the respective ink ejection nozzles 7 of the print head 4, the pressure inside the print head 4 and the inside of the valve device 20 are lowered accordingly, and the ink is discharged. When the difference from the pressure on the tank 2 side exceeds a certain value (threshold value), the differential pressure overcomes the bias of the spring 27 and the first valve 26 opens. As a result, the first valve 26 opens the ink tank 2 side and the valve device 20 side, so that the ink 3 corresponding to the amount of the ink droplets 14 ejected from the ink ejection nozzles 7 is contained in the print head 4. Newly supplied. When a predetermined amount of ink 3 is supplied and the pressure is balanced, as shown in FIG. 2, the first valve 26 is closed again by the bias of the spring 27, and the supply of the ink 3 is shut off. In this way, the first valve 26 moves up and down to open and close between the ink tank 2 and the ink chamber 25, and supply of the ink 3 from the ink tank 2 to the valve device 20 can be controlled. The material of the first valve 26 is not limited, but it is preferable to form the first valve 26 from, for example, a rubber elastic body (elastomer) because it has a high closing property.

  Here, in the present invention, the second valve is provided between the opening and closing port of the first valve 26 and the outside air communication hole 21. Specifically, a second valve 29 is provided in the middle of the ink supply pipe 24 and upstream of the first valve 26. The second valve 29 opens and closes the liquid flow path of the ink supply pipe 24 and is opened after the opening of the first valve 26. For example, the spring 40 that biases the second valve 29 toward the closing side may be set to have a slightly larger biasing force than the spring 27 of the first valve 26. Instead of the spring 40, an elastic body such as rubber may be used. Thereby, the rapid supply of the ink 3 from the ink tank 2 to the print head 4 can be suppressed, and the dynamic negative pressure of the ink 3 in the print head 4 can be prevented from changing rapidly.

That is, in the present invention, since the second valve is provided between the opening and closing port of the first valve 26 and the outside air communication hole 21, the print head 4 is printed as shown in FIG. When the print head 4 is started, that is, when the print head 4 shifts from the standby state to the print state, the delay time t occurs in the change in the dynamic negative pressure of the ink 3 and the ink 3 flows into the print head 4 suddenly. Is suppressed, and the dynamic negative pressure of the ink 3 in the print head 4 does not change rapidly. Similarly, when the print head 4 shifts from the printing state to the standby state, the delay time t occurs in the change in the dynamic negative pressure of the ink 3 and the dynamic negative pressure of the ink 3 in the print head 4 changes abruptly. Disappear. This is because the response of the first valve 26 is delayed and the second valve 29 is opened, and as a result, the ink 3 gently flows into the print head 4 and a sudden dynamic negative pressure change occurs. This is considered to be suppressed. In this case, the reference plane x ₀ meniscus position x of the ink discharge nozzle 7 shown in FIG. 4 to be stable in the equilibrium position at a predetermined distance. Therefore, even when the frequency characteristic of ink discharge is high, the meniscus position of the ink 3 in the ink discharge nozzle 7 becomes stable, so that the ink droplet 14 can be stably discharged, and the liquid discharge performance. Can be improved.

On the other hand, the conventional ink supply device does not include the second valve 29. Therefore, as shown in FIG. 6, when the print head 4 shifts from the standby state to the printing state, the first valve 29 is provided. When the valve 26 is opened, the ink suddenly flows into the print head 4 and the dynamic negative pressure of the ink 3 changes abruptly. In this case, the meniscus position x of the ink 3 in the ink discharge nozzle 7 shown in FIG. 4 fluctuates rapidly, so that it oscillates up and down from an equilibrium position at a predetermined distance from the reference plane x ₀ and eventually stabilizes while being attenuated. It becomes like this. At this time, when the frequency characteristic of ink ejection is high, the next ink droplet 14 is ejected before the meniscus position x is stabilized, the ejection direction and size of the ink droplet 14 become unstable, and the print The image quality deteriorated.

  Further, the ink tank 2 shown in FIG. 2 can be removed from the ink supply pipe 24 connected to the bottom side thereof. As a result, the ink tank 2 can be detached from the ink supply tube 24 of the head cartridge 1. Accordingly, the ink tank 2 that has been emptied by supplying the ink 3 contained therein to the print head 4 can be replaced with a new one.

  FIG. 7 is a schematic view showing a second embodiment of the head cartridge according to the present invention. In this embodiment, a duck bill type check valve 30 is attached to the outside air communication hole 21 of the ink tank 2. This duckbill type check valve 30 serves as a second valve that adjusts the supply of air taken into the interior of the ink tank 2 from the outside, and is opened after the opening of the first valve 26. It has become. The duckbill type check valve 30 normally has a closed mouth, and opens when the pressure difference is in the forward direction, allowing the fluid to flow freely. Thus, it is possible to prevent the ink 3 from being blown out from the outside air communication port 21 and being contaminated during the handling of the ink tank 2. The duckbill check valve 30 can be designed to operate under a predetermined pressure according to its size, geometric shape, and material blending characteristics.

  Thus, when the ink 3 in the ink tank 2 is supplied to the print head 4 and the amount thereof is reduced, the air corresponding to the reduced amount of the liquid becomes the outside air communication hole 21 provided with the duckbill type check valve 30. Therefore, the pressure inside the ink tank 2 is stabilized without changing rapidly. Even in this case, since the ink 3 is suppressed from flowing into the print head 4 from the ink tank 2 rapidly, the dynamic negative pressure of the ink 3 in the print head 4 changes rapidly as shown in FIG. No longer. Therefore, since the meniscus position x of the ink discharge nozzle 7 is stabilized, ink droplets can be stably discharged and the image quality of the print image can be stabilized.

  As described above, when the ink tank 2 is detachable from the ink supply pipe 24, it is convenient to attach the duckbill type check valve 30 to the outside air communication hole 21. This is because the check valve 30 can prevent the ink 3 from being blown out from the outside air communication port 21 and being contaminated during the handling of the ink tank 2.

  FIG. 8 is a schematic view showing a third embodiment of the head cartridge according to the present invention. In this embodiment, an ink reservoir 35 is provided on the upstream side of the first valve 26 in the middle of the ink supply pipe 24, and a second portion is provided at the opening of the outside air communication hole 36 provided in the ink reservoir 35. A duckbill type check valve 30 is attached as a valve. Also in this case, since the duckbill type check valve 30 is provided between the opening and closing port of the first valve 26 and the outside air communication hole 21, the first valve 26 is opened and the print head 4 is opened. When the ink 3 is supplied, the check valve 30 opens later, and air is taken into the ink reservoir 35. Accordingly, since the ink 3 is prevented from flowing into the print head 4 from the ink tank 2 rapidly, the dynamic negative pressure of the ink 3 in the print head 4 does not change rapidly. Therefore, since the meniscus position x of the ink discharge nozzle 7 is stabilized, ink droplets can be stably discharged and the image quality of the print image can be stabilized.

  FIG. 9 is a schematic view showing a fourth embodiment of the head cartridge according to the present invention. In this embodiment, the pressure fluctuation adjusting means 31 is provided in the middle of the ink supply pipe 24 on the downstream side of the opening / closing port of the first valve 26, and is applied to the head cartridge 1 shown in FIG. is there. The pressure fluctuation adjusting means 31 is configured to start the first valve 26 from when the first valve 26 opens the liquid flow path of the ink supply pipe 24 and the ink 3 is supplied from the ink tank 2 to the print head 4. The pressure fluctuation inside the print head 4 until the liquid flow path is closed is moderated, and is provided in the valve device 20 and includes a connecting pipe 32, a closing member 33, and a pressing member 34. Has been.

  The connecting pipe 32 is connected to one side surface of the ink chamber 25 and extends from the ink chamber 25 by a predetermined distance in the parallel direction and is bent in the vertical direction. In FIG. 9, only the upper end of the connection pipe 32 is opened. The closing member 33 is disposed so as to close the opened upper end portion of the connection pipe 32, and the upper end side of the connection pipe 32 is moved in the vertical direction while maintaining the sealed state of the ink 3 in the connection pipe 32. It is attached to be movable. The pressing member 34 is attached between the upper surface side of the closing member 33 and a predetermined fixing member, and biases the closing member 33 downward so as to press the ink 3 in the connection pipe 32. It is a coil spring. The pressure fluctuation adjusting means 31 is not limited to the one having the above-described configuration, and any pressure fluctuation adjusting means 31 can be used as long as it controls the pressure fluctuation inside the ink chamber 25 and the ink pressurizing chamber 12 of the print head 4 to be gentle. For example, a configuration having a diaphragm may be used.

  By providing the pressure fluctuation adjusting means 31 as described above, when the ink droplets 14 are ejected from the respective ink ejection nozzles 7 of the print head 4 as described above, the ink pressurizing chamber 12 (see FIG. 4) is used as the ink chamber. The pressure of the ink 3 between 25 and 25 decreases. When such a pressure drop of the ink 3 occurs, the first valve 26 is controlled so that the pressure fluctuation adjusting means 31 moderates the pressure fluctuation inside the ink chamber 25 and the ink pressurizing chamber 12 of the print head 4. The space between the ink tank 2 and the ink chamber 25 is opened. As a result, the ink 3 can gently flow from the ink tank 2 side to the ink chamber 25 side. When the pressure on the ink chamber 25 side returns to the steady state, the first valve 26 closes the space between the ink tank 2 and the ink chamber 25.

That is, as shown in FIG. 10A, even if the first ink droplet 14 is ejected from the ink ejection nozzle 7 of the print head 4 by the first ink ejection pulse as shown in FIG. Since the operating pressure of the first valve 26 is not reached, the meniscus position x of the ink 3 slightly recedes and approaches the reference plane x ₀ as shown by the solid line in FIG. At this time, since the valve device 20 is provided with the pressure fluctuation adjusting means 31, the retreat distance of the meniscus position x is small.

Next, as shown in FIG. 10A, the second ink droplet 14 is ejected from the ink ejection nozzle 7 of the print head 4 by the second ink ejection pulse. At this time as well, since the first valve 26 does not reach the operating pressure, the meniscus position x of the ink 3 further recedes slightly to the reference plane x ₀ as shown by the solid line in FIG. Get closer. At this time as well, by providing the pressure fluctuation adjusting means 31, the retreat distance of the meniscus position x is small.

  As shown in FIG. 10A, when the third ink droplet 14 is discharged from the ink discharge nozzle 7 of the print head 4 by the third ink discharge pulse, as shown in FIG. The first valve 26 reaches the operating pressure and is opened. As shown in FIG. 10C, the response is delayed by the delay time t and the duckbill check valve 30 is opened. The ink 3 gently flows into the print head 4 due to the time lag of the two valves (26, 30), so that the maximum value and minimum value of the meniscus position x of the ink 3 are shown in FIG. The amount of displacement α becomes smaller and stable. For this reason, since the ink droplet 14 is ejected stably, the image quality of the print image can be stabilized.

On the other hand, in the case of the conventional ink supply device, as shown in FIG. 10A, the first ink droplet 14 is ejected from the ink ejection nozzle 7 of the print head 4 by the first ink ejection pulse. In some cases, the first valve 26 does not reach the operating pressure, so that the meniscus position x of the ink 3 moves backward and approaches the reference plane x ₀ as shown by the one-dot chain line in FIG. At this time, since the duck bill type check valve 30 as the second valve is not attached to the outside air communication hole 21 of the ink tank 2, air is rapidly taken in, and the dynamic negative pressure in the print head 4 is reduced. The meniscus position x changes rapidly due to a sudden change. Further, since the valve device 20 is not provided with the pressure fluctuation adjusting means 31, the distance by which the meniscus position x moves backward is large.

  Next, when the second ink droplet 14 is ejected, the meniscus position x of the ink 3 is increased as shown in FIG. 10D because the first valve 26 does not reach the operating pressure. Retreat rapidly. When the third ink droplet 14 is discharged and the first valve 26 of the device 20 finally reaches the operating pressure and is opened, the ink 3 suddenly flows into the ink chamber 12 of the print head 4. Therefore, as indicated by the alternate long and short dash line in FIG. 10D, the meniscus position x of the ink 3 in the ink discharge nozzle 7 vibrates up and down. Further, as shown in FIG. 10A, the next ink ejection pulse is generated before the meniscus position x is stabilized, and the next ink droplet 14 is ejected from the ink ejection nozzle 7 of the print head 4. . As described above, in the conventional ink supply device, the meniscus position x is not stable, and the displacement amount β between the maximum value and the minimum value becomes large, so that ink ejection becomes unstable, and color unevenness occurs during printing. And white streaks may appear as image quality degradation.

  In the above description, a head cartridge including an ink supply device that suppresses abrupt ink supply to the print head 4 and stabilizes the meniscus position of the ink 3 in the ink discharge nozzle 7 has been described. However, the present invention is not limited thereto, and the second valve may be provided anywhere as long as the second valve is provided between the outside air communication port 21 and the first valve 26. The second valve is required to be opened after the opening of the first valve, but various structures are conceivable as a mechanism for opening and closing the valve. For example, a spring may be used, a repulsive force of an elastic body such as rubber may be used, or an electromagnetic valve may be used if cost is not an issue. Furthermore, although the response is deteriorated, the same effect can be obtained even when a plurality of valves are provided in series with the ink supply pipe 24 as the second valve.

  Since the relationship between the first valve and the second valve is different depending on the configuration and operation status of the device, it cannot be generally stated. For example, if the operating pressure of the second valve is too weak with respect to the first valve, the response is improved and the ink 3 suddenly flows into the print head 4. In addition, if the operating pressure of the second valve is too strong for the first valve, the second valve may open after the first valve is opened several times. In this case, since the negative pressure on the first valve side is strong, the ink 3 is likely to flow rapidly into the print head 4. Even when the operating pressures of the first valve and the second valve are made equal, both may be possible depending on the configuration of the apparatus and the like, and it is necessary to confirm an appropriate strength relationship by experiment.

  In FIG. 9, the pressure fluctuation adjusting means 31 is applied to the head cartridge 1 shown in FIG. 7, but the present invention is not limited to this, and can be applied to head cartridges of other embodiments.

  Furthermore, in the above description, an example applied to an ink jet printer has been described. However, the present invention is not limited to this, and any device that discharges liquid from a liquid discharge nozzle of a liquid discharge head may be used. . For example, the present invention can be applied to a facsimile machine or a copying machine whose recording system is an inkjet system.

  The liquid ejected from the nozzles of the liquid ejection head of the liquid ejection apparatus is not limited to ink, and any other liquid ejection apparatus can be used as long as it can form a dot row or a dot by ejecting the liquid in the liquid chamber. Can be applied. For example, the present invention can be applied to a liquid discharge device for discharging a DNA-containing solution onto a pallet in DNA identification or the like, or a liquid discharge device for discharging a liquid containing conductive particles for forming a wiring pattern of a printed wiring board. Can do.

1 is a perspective view showing an embodiment of an ink jet printer as an example of a liquid ejection apparatus according to the present invention. It is a schematic diagram showing an embodiment of a head cartridge according to the present invention. FIG. 3 is a cross-sectional view illustrating a state in which ink droplets are ejected from ink ejection nozzles of the print head illustrated in FIG. 2. FIG. 4 is an enlarged cross-sectional view showing a portion P of the print head shown in FIG. 3. In the head cartridge according to the present invention, it is a diagram showing a state in which a sudden change in dynamic negative pressure of ink in the print head is suppressed. In the conventional head cartridge, it is a figure which shows the state in which the dynamic negative pressure of the ink in a print head changes rapidly. It is a schematic diagram showing a second embodiment of a head cartridge according to the present invention. FIG. 6 is a schematic diagram showing a third embodiment of a head cartridge according to the present invention. FIG. 6 is a schematic diagram showing a fourth embodiment of a head cartridge according to the present invention. 10 is a graph showing a state in which the meniscus position of the ink discharge nozzle is stabilized by the head cartridge shown in FIG. 9.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Head cartridge 2 ... Ink tank 3 ... Ink 4 ... Print head 5 ... Ink supply apparatus 6 ... Nozzle member 7 ... Ink discharge nozzle 12 ... Ink pressurization chamber 14 ... Ink droplet 20 ... Valve apparatus 21 ... Outside air communication hole 24 ... Ink supply pipe 25 ... Ink chamber 26 ... First valve 27 ... Spring 28 ... Ink delivery pipe 29 ... Second valve 30 ... Duck bill type check valve 31 ... Pressure fluctuation adjusting means 32 ... Connection pipe 33 ... Closure member 34 ... Pressing member 35 ... Ink reservoir 36 ... Outside air communication hole 100 ... Inkjet printer

Claims (13)

  A liquid tank having an external air communication hole that takes in air corresponding to the reduced amount when a predetermined liquid is stored inside and the amount of the liquid is reduced when the liquid is supplied to the outside. A liquid tank provided with a mold check valve. A liquid tank for storing a predetermined liquid therein;
A liquid discharge head for supplying a liquid from the liquid tank and discharging a predetermined liquid from a liquid discharge nozzle formed on the nozzle member;
The liquid tank is energized to close the liquid flow path of a liquid supply pipe that supplies the liquid in the liquid discharge head to the liquid discharge head, and is generated when the liquid is discharged from the liquid discharge nozzle of the liquid discharge head. A first valve that opens the liquid flow path due to a pressure drop in the liquid discharge head, and air corresponding to the decrease when the amount of liquid in the liquid tank is reduced by supplying the liquid in the liquid tank to the liquid discharge head. A liquid supply device having an outside air communication hole to be taken into the liquid tank;
In the head cartridge provided with
A head cartridge, wherein a second valve is provided between the opening and closing port of the first valve and the outside air communication hole, and the second valve opens after the opening of the first valve.   In the middle of the liquid supply pipe, on the downstream side of the opening and closing port of the first valve, when the first valve opens the liquid flow path and liquid is supplied from the liquid tank to the liquid discharge head. 3. The head cartridge according to claim 2, further comprising pressure fluctuation adjusting means for moderating pressure fluctuation inside the liquid discharge head until the first valve closes the liquid flow path.   4. The head cartridge according to claim 2, wherein the liquid tank is detachable from the liquid supply pipe.   4. The head cartridge according to claim 2, wherein the second valve is provided in the outside air communication hole.   4. The head cartridge according to claim 2, wherein the second valve is provided in the middle of the liquid flow path of the liquid supply pipe.   7. The head cartridge according to claim 5, wherein the second valve is a duckbill type check valve. A liquid tank that stores a predetermined liquid therein, a liquid discharge head that supplies liquid from the liquid tank and discharges the predetermined liquid from a liquid discharge nozzle formed on the nozzle member, and the liquid in the liquid tank is the liquid The liquid supply pipe supplied to the discharge head is energized so as to close the liquid flow path, and the pressure in the liquid discharge head generated when the liquid is discharged from the liquid discharge nozzle of the liquid discharge head A first valve that opens the liquid flow path, and external air communication that supplies the liquid in the liquid tank to the liquid discharge head and takes air corresponding to the reduced amount into the liquid tank when the amount decreases. A head cartridge having a liquid supply device having a hole is detachably stored in the apparatus main body, and liquid is discharged from the liquid discharge head of the head cartridge. A liquid discharge apparatus,
A second valve is provided between the opening and closing port of the first valve of the head cartridge and the outside air communication hole, and the second valve opens after the opening of the first valve. Liquid ejection device.   In the middle of the liquid supply pipe of the head cartridge, on the downstream side of the opening and closing port of the first valve, the first valve opens the liquid flow path and the liquid is supplied from the liquid tank to the liquid discharge head. 9. The liquid according to claim 8, further comprising pressure fluctuation adjusting means for moderating pressure fluctuation inside the liquid discharge head from when the first valve is closed until the first valve closes the liquid flow path. Discharge device.   10. The liquid ejection apparatus according to claim 8, wherein the liquid tank is detachable from the liquid supply pipe.   The liquid ejection device according to claim 8 or 9, wherein the second valve is provided in the outside air communication hole.   10. The liquid ejection apparatus according to claim 8, wherein the second valve is provided in the middle of the liquid flow path of the liquid supply pipe.   The liquid ejection device according to claim 11 or 12, wherein the second valve is a duckbill type check valve.

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