CN1771133A - liquid injection device - Google Patents

Abstract

For cleaning a recording head, a printer seals nozzles by means of a cap member and thus forms a closed circulatory system. In this state, a gear pump is activated and draws waste ink and the air from the cap member. The waste ink and the air then flow in the cap member, a check valve, a tube, the gear pump, and a different tube in this order and are introduced into a first ink cartridge. The air is introduced into a second ink cartridge through a corresponding tube as pressurized air. The check valve prevents the waste ink and the pressurized air from returning to the cap member. This suppresses backflow of the liquid and the air, and ink ejection is performed effectively.

Description

liquid injection device

technical field

The present invention relates to liquid ejection devices.

Background technique

Conventionally, an inkjet recording device is collectively referred to as a type of liquid ejection device. Inkjet recording devices include "off-carriage" types in which an ink holder is connected to a recording head via an ink supply tube. The ink holder is provided in an ink tank as an ink container. The ink holder is pressurized with pressurized air introduced into the ink cartridge, for example by a pump. This causes the ink in the ink holder to be sent to the recording head through the ink supply tube, so that the recording head is supplied with ink. Then, the ink is ejected from the nozzles of the recording head toward the recording paper as ink droplets for recording characters or images.

Typically, when it is necessary to prevent ink ejection problems, the inkjet recording apparatus performs cleaning that discharges air bubbles or ink with increased viscosity from the nozzles of the recording head to the waste ink tank.

In the off-carriage type inkjet recording apparatus, the waste ink tank may be integrally formed with the ink tank. Various such devices have been proposed (for example, see Patent Document 1).

As shown in FIG. 7 , Patent Document 1 describes an inkjet recording apparatus 100 having an ink cartridge 102 for accommodating an ink pack 101 . The ink pack 101 is connected to the recording head 105 via the ink supply tube 104 connected to the ink supply port 103 of the ink tank 102 . The inkjet recording device 100 also includes a cap 106 for receiving waste ink from the recording head 105 . The cap 106 is connected to the pressurization port 109 of the ink cartridge 102 via the ink recovery tube 107 and the pump 108 . A valve 112 and a pressure sensor 113 are connected to the discharge port 110 of the ink cartridge 102 via a passage 111 . Valve 112 opens ink cartridge 102 when needed. The pressure sensor 113 detects the pressure in the ink tank 102 . A stopper 114 is formed in the ink supply tube 104 for selectively inhibiting and allowing ink flow in the ink supply tube 104 .

When the pump 108 is activated while the stopper 114 holds the ink supply tube 104 open, waste ink and air are drawn from the cap 106 into the ink cartridge 102 via the ink recovery tube 107 . This increases the pressure in the ink tank 102 to press the ink pack 101 to supply ink to the recording head 1 via the ink supply tube 104 .

When the inkjet recording apparatus 100 is operated to restore ink ejection performance, the stopper 114 blocks the ink supply tube 104 and the pump 108 is activated. When the pressure in the ink tank 102 reaches a predetermined level, the ink supply tube 114 is opened. This causes the ink to flow quickly to the recording head 105, thereby removing the ink and air bubbles in the ink from the nozzle portion of the recording head 105. In this way, ink ejection performance is restored by pressurization.

In the inkjet recording apparatus 100, it is desirable that ink is properly supplied to the recording head 105 for efficient printing. Therefore, it is necessary to keep the ink pack 101 in a properly pressurized state.

Nowadays, ink jetting devices are required to be compact, and gear pumps meeting such requirements have attracted attention.

However, if the inkjet recording apparatus 100 includes a gear pump, and the suction holding performance of the pump decreases due to manufacturing errors in the pump, air or ink may flow back into the cap 106 . This makes it difficult to maintain the ink pack 101 in a properly pressurized state. If ink backflow occurs, a mixture of waste ink and air leaks to the cap 106, generating air bubbles in the cap 106, thereby contaminating the recording head 105.

Furthermore, when the inkjet recording apparatus 100 seals the nozzles of the recording head 105 with the cap 106, the inkjet recording apparatus 100 forms a closed circulation system. Therefore, if the pressure in the cap 106 and the pressure in the recording head 105 are unbalanced, or the pressure in the cap 106 becomes higher than the pressure in the recording head 105, air and waste ink will flow from the cap 106 back to the recording head 105.

If the suction holding performance of the gear pump is relatively low, the nozzles passing through the recording head 105 are sealed by the cap 106, and air and waste ink flow to the ink tank 102 when the gear pump is activated. However, if the gear pump is stopped, air and waste ink will flow back to the cap 106 . Such air and waste ink can enter the recording head 105 through the nozzles of the recording head 105 . This affects to some extent the meniscus of ink generated in the nozzle, thereby hindering desired ink ejection of the ink recording apparatus 100 .

Patent Document 1: Japanese Laid-Open Patent Publication No. 2001-162838.

Contents of the invention

Accordingly, an object of the present invention is to provide a liquid ejection device capable of reliably ejecting liquid by suppressing backflow of liquid and air.

To achieve the foregoing and other objects, the present invention provides a liquid ejecting device. The apparatus has: a liquid ejection head for ejecting liquid; a cover member for receiving waste liquid discharged from the liquid ejection head; a waste liquid box for retaining the waste liquid; Waste is directed to the gear pump in the waste box. The device also includes waste liquid backflow suppressing means for suppressing backflow of the waste liquid to the cover part.

If the suction retention performance of the gear pump is lowered due to, for example, manufacturing errors, when the gear pump is not in operation, the waste liquid may flow back to the cover member through the gear pump. However, this backflow is suppressed by the backflow suppression device. This suppresses contamination of the liquid ejection head by waste liquid flowing as air bubbles from the cap member. Furthermore, when the liquid ejection apparatus forms a closed circulation system by sealing the liquid ejection head with the cap member, backflow of waste liquid from the cap member to the liquid ejection head is suppressed. The crescent shape of the liquid formed in the liquid ejection head is thereby maintained. Therefore, the liquid ejecting device is allowed to reliably eject liquid.

The waste liquid return suppressing device of the liquid ejecting device may be arranged between the waste liquid box and the gear pump or between the gear pump and the cover member. If the waste liquid backflow suppressing device is arranged between the waste liquid box and the gear pump, the waste liquid is introduced into the waste liquid box through the waste liquid backflow suppressing device after having been sucked by the gear pump. This allows the waste liquid backflow suppressing device to suppress backflow of waste liquid from the waste liquid box.

If the waste liquid backflow suppressing device is provided between the gear pump and the cover member, the waste liquid is sucked by the gear pump through the waste liquid backflow suppressing device after having been received by the cover member. Therefore, in both cases, even if the suction retention performance of the gear pump is relatively low, backflow of waste liquid to the cover member can be suppressed when the gear pump is not in use. Especially if the waste liquid backflow suppressing device is provided between the gear pump and the cover member, when the gear pump is operated, negative pressure acts entirely on the passage between the cover member and the waste liquid backflow suppressing device. Therefore, when, for example, the cap member seals the nozzle, the backflow of waste liquid to the liquid ejection head through the cap member is further suppressed.

The backflow suppression means of the liquid ejection device may be formed by valve means. The valve means inhibits backflow of waste liquid from the waste liquid box to the cover member. This allows the liquid ejection device including the valve device to suppress contamination of the liquid ejection head by waste liquid flowing from the cap member as air bubbles. Furthermore, when the liquid ejection device forms a closed circulation system, backflow of waste liquid to the liquid ejection head is suppressed.

Another aspect of the present invention is a liquid ejection apparatus including: a liquid ejection head for ejecting a liquid; a liquid holder for holding the liquid to be ejected and supplying the liquid to the liquid ejection when pressurized by pressurized air head; and a gear pump for generating the pressurized air used to pressurize the liquid holder. The device also includes air backflow suppression means allowing pressurized air to be supplied only to the liquid holder.

In this aspect of the invention, the air backflow suppressing means restricts the supply of pressurized air for supply to the liquid holder. This inhibits backflow of pressurized air from the liquid holder, thereby preventing pressure drop in the liquid holder. Therefore, the liquid holder is effectively pressurized to be allowed to properly supply the liquid to the liquid ejection head. This allows the liquid ejecting device to reliably eject liquid. Furthermore, if, for example, the liquid ejection device forms a closed circulation system, by preventing the backflow of pressurized air, the backflow of pressurized air to the liquid ejection head is suppressed. Thus, the liquid crescent shape formed in the liquid ejection head is maintained. Therefore, the liquid ejecting device reliably ejects the liquid.

The air backflow suppression device may be arranged between the liquid holder and the gear pump or upstream of the gear pump. If the air backflow suppression device is arranged between the liquid holder and the gear pump, pressurized air generated by the gear pump is supplied to the liquid holder through the air backflow suppression device. Air backflow suppression device suppresses backflow of pressurized air. This suppresses the pressure drop in the liquid holder, allowing the liquid holder to properly supply the liquid to the liquid ejection head.

If the air backflow suppressing device is provided upstream of the gear pump, the upstream backflow of the pressurized air generated by the gear pump and sent downstream from the gear pump is suppressed. More precisely, even if the suction retention performance of the gear pump is reduced by manufacturing errors, the return flow of pressurized air is prevented. Furthermore, if, for example, the liquid ejection device forms a closed circulation system, the backflow of pressurized air to the liquid ejection head is suppressed. In addition, since the pressurized air does not return from the downstream side of the gear pump to the upstream side, the pressure drop in the liquid holder is suppressed.

The air backflow suppression means may be formed by valve means. This valve arrangement allows pressurized air to be supplied only to the liquid holder. This allows the liquid ejection device having the valve device to suppress the pressure drop of the pressurized air supplied to the liquid holder. Furthermore, if the liquid ejecting device forms a closed circulation system, the backflow of pressurized air to the liquid ejecting head is suppressed.

Another aspect of the present invention is a liquid ejection device having: a liquid ejection head for ejecting liquid; a cap member for receiving liquid ejected from the liquid ejection head as waste liquid; and a cap member for suctioning from the cap member A gear pump of waste liquid and air; and a liquid retainer having: a waste liquid retainer portion for holding waste liquid sucked by the gear pump and containing air as pressurized air; and for holding liquid using pressurized air Supply to the liquid holding portion of the liquid ejection head. The device also includes fluid backflow suppression means for suppressing backflow of waste fluid and pressurized air to the cover member.

The fluid backflow suppressor suppresses backflow of waste liquid and pressurized air to the cover member. Therefore, if the suction retention performance of the gear pump is relatively low, the backflow of waste liquid and pressurized air to the cover member can also be suppressed when the gear pump is not in operation. This suppresses the pressure drop of the pressurized air, so that the liquid holder suitably supplies the held liquid to the liquid ejection head with the pressurized air. In addition, contamination of the liquid ejection head by waste liquid and pressurized air flowing as air bubbles from the cap member is suppressed. Furthermore, when the liquid ejection apparatus forms a sealed circulation system, for example, by sealing the liquid ejection head with the cap member, backflow of pressurized air and waste liquid to the liquid ejection head through the cap member when the gear pump is not in use is suppressed. The crescent shape of the liquid formed in the liquid ejection head is thereby maintained. As a result, the liquid ejecting device reliably ejects liquid.

The fluid backflow suppressing device may be arranged between the liquid holder and the gear pump or between the gear pump and the cover member. If the fluid backflow suppression device is arranged between the liquid holder and the gear pump, waste liquid and pressurized air are introduced through the fluid backflow suppression device into the waste liquid holder part of the liquid holder after having been sucked from the cover part. Backflow of waste fluid and pressurized air from the waste fluid holder section to the gear pump is suppressed. Therefore, even if the gear pump has relatively low suction retention performance, contamination of the liquid ejection head by waste liquid as air bubbles flowing from the cap member and pressurized air is further suppressed when the gear pump is not in use. The pressure drop of the pressurized air in the waste liquid holding portion is also suppressed, so that the liquid holder portion of the liquid holder properly supplies the liquid to the liquid ejection head using the pressurized air. If the fluid backflow suppressing device is provided between the gear pump and the cover member, the gear pump sucks waste liquid and air from the cover member through the fluid backflow suppressing device. Therefore, when the liquid ejection apparatus forms a sealed circulation system, for example, by sealing the liquid ejection head with the cap member, backflow of pressurized air and waste liquid to the liquid ejection head through the cap member when the gear pump is operated is further suppressed. This maintains the crescent shape of the liquid formed in the liquid ejection head. Therefore, the liquid ejecting device reliably ejects the liquid.

The fluid backflow suppression means may be formed by valve means. The valve means inhibits backflow of waste liquid and pressurized air to the cover member. This enables the liquid ejection device including the valve device to suppress contamination of the liquid ejection head by waste liquid and pressurized air flowing from the cap member as air bubbles. Furthermore, when the liquid ejection apparatus forms a closed circulation system, for example, by sealing the liquid ejection head with a cap member, backflow of pressurized air and waste liquid to the liquid ejection head is suppressed.

The valve device may include: an inlet portion into which at least one of waste liquid or pressurized air is introduced; an outlet portion through which waste liquid or pressurized air flows from the inlet portion to the outside; and a valve body for: The pressure of the air is not lower than a predetermined reference level, the valve body connects the inlet part and the outlet part to each other, and the valve body separates the inlet part from the outlet part if waste liquid and pressurized air are returned to the inlet part from the outlet part.

The valve body separates the inlet section from the outlet section if waste fluid and pressurized air flow back. Thus, the waste liquid is introduced into the waste liquid box or the waste liquid holder portion, and the backflow of the waste liquid is suppressed. This suppresses contamination of the liquid ejection head by waste liquid flowing from the cap member. Furthermore, by separating the inlet part from the outlet part, the pressure drop in the liquid holder is suppressed. Thereby, the liquid holder is made to properly supply the liquid to the liquid ejection head. Therefore, the liquid ejecting device reliably ejects the liquid.

The valve body of the valve device may be configured to connect the inlet part and the outlet part to each other if the difference between the pressure in the inlet part and the pressure in the outlet part exceeds a predetermined reference value, and if the pressure in the inlet part and the outlet part The difference in pressure in is equal to or less than the reference value, which separates the inlet section from the outlet section. If eg the gear pump is not running for a considerable time, due to a slight leak of pressurized air, the pressure in the outlet section will be reduced to atmospheric pressure, thereby eliminating the difference between the pressure in the inlet section and the pressure in the outlet section. Even in this state, the inlet portion and the outlet portion are kept in a state separated from each other. This prevents waste liquid and pressurized air from flowing back when the liquid ejection device is moved.

Furthermore, the valve body separates the inlet part from the outlet part if, for example, the gear pump is not operating and the pressure in the outlet part rises, or a return flow of waste liquid and pressurized air may occur. More precisely, the valve arrangement prevents waste fluid and pressurized air from flowing back when the gear pump is not in use. Therefore, the liquid ejecting apparatus including the gear pump suppresses contamination of the liquid ejecting head by waste liquid flowing from the cap member as air bubbles. Furthermore, by separating the inlet part from the outlet part, pressure drops in the liquid holder are prevented from occurring. Therefore, the liquid holder is effectively pressurized to be allowed to properly supply the liquid to the liquid ejection head. In addition, when the liquid ejection device forms a closed circulation system, backflow of waste liquid and pressurized air to the liquid ejection head is suppressed. Therefore, the liquid ejecting device is allowed to reliably eject liquid.

Description of drawings

1 is a perspective view schematically showing a printer according to a first embodiment of the present invention;

Fig. 2 is a block diagram showing an ink supply system for a recording head;

3 is a cross-sectional view showing the structure of a check valve;

4(a), (b) and (c) are cross-sectional views each showing the operating state of the check valve;

5 is a block diagram showing an ink supply system for a recording head according to a second embodiment of the present invention;

6 is a cross-sectional view showing the structure of the check valve and the structure of the cover;

Fig. 7 is a block diagram schematically showing a prior art liquid ejection device.

Detailed ways

(first embodiment)

A first embodiment of the present invention will be described below with reference to FIGS. 1 to 4 .

As shown in FIG. 1 , a printer 1 serving as a liquid ejecting device includes a substantially parallelepiped frame 2 . A paper feed tray 3 is formed on the upper surface of the frame 2 , and a paper output tray 4 is provided on the front surface of the frame 2 . Each of the paper feed tray 3 and the paper output tray 4 is configured to be accommodated in the frame 2 in a state of being folded with an unillustrated hinge mechanism.

The deck 5 extends longitudinally in the frame 2 . Recording paper is inserted into the frame 2 via a paper feed tray 3 and supplied to a platen 5 by a paper feed mechanism not shown. Then, the recording paper is conveyed from the frame 2 to the outside via the paper output tray 4 .

A guide member 6 is provided in the frame 2 and extends parallel to the platen 5 . The carriage 7 is supported by a guide member 6 which passes through the carriage 7 . The carriage 7 is movable along the guide member 6 . A carriage motor (not shown) is fastened to the frame 2 . The carriage 7 is operatively connected to the carriage motor by a geared belt (not shown) around a pair of pulleys not shown. When the carriage motor is running, the driving force generated by the carriage motor is transmitted to the carriage 7 via the gear belt. When powered by the carriage motor, the carriage 7 reciprocates (in the main scanning direction) along the guide member 6 parallel to the platen 5 .

A recording head 8 serving as a liquid ejection head is formed on the lower surface of the carriage 7 (opposite to the platen 5 ). The recording head 8 includes a nozzle surface 8a (see FIG. 2 ) opposed to the recording paper. The nozzle surface 8 a includes 6 nozzle rows (not shown), each row including a number n (n is a natural number) of jets N ( FIG. 2 ). The number of nozzles N formed in each nozzle row and the number of nozzle rows may be modified as necessary.

The first ink tank 9 and the second ink tank 10 are provided in the frame 2 as liquid containers. The first and second ink tanks 9, 16 supply ink as a liquid corresponding to the colors of the nozzles (in the first embodiment, black, cyan, magenta, yellow, light cyan, and light magenta) to the recording head 8. . Then, the ink is pressurized by the piezoelectric element 8b (FIG. 2), and ejected from the corresponding nozzles N of the recording head 8 as ink droplets. The ink droplets produce black, cyan, magenta, yellow, light cyan, or light magenta dots on the recording paper.

In the printer 1, an area where the carriage 7 reciprocates in order to eject ink droplets to recording paper to perform printing is defined as a printing area. In addition, a non-printing area is determined in the printer 1 for sealing the nozzles N when printing is not performed. As shown in FIG. 1 , a cap holder 11 is formed in the non-printing area.

The cap member 12 is provided in the cap holder 11 opposite to the nozzle surface 8 a of the recording head 8 . The cap holder 11 raises the cap member 12 by an unillustrated driving mechanism so that the cap member 12 closely contacts the ejection surface 8a, thereby sealing the nozzles N of the recording head 8 . As shown in FIG. 2 , the first communication port 12 a and the second communication port 12 b are defined in the bottom of the cover member 12 and communicate with the inside of the cover member 12 . A cover opening valve 13 is connected to the first communication port 12a via a tube T1. When necessary, the cap opening valve 13 opens a space defined by the cap member 12 and the nozzle surface 8a held in close contact with each other. The second communication port 12b is connected to a suction port (not shown) of the gear pump GP via a tube T2. The gear pump GP includes gears G1, G2. The gears G1 , G2 are rotated by driving force transmitted from an unillustrated driving motor, thereby applying a negative pressure to the lid member 12 . When the cap opening valve 13 is closed and the cap member 12 seals the nozzle surface 8a, the nozzle N is cleaned by applying negative pressure to the nozzle N of the nozzle surface 8a by the gear pump GP.

The check valve 14 is connected to a discharge port (not shown) of the gear pump GP via a tube T3. The liquid inlet part 15 of the first ink cartridge 9 is connected to the check valve 14 via the tube T4.

The first ink tank 9 has two holding portions defined by a spacer 16 . One holder part accommodates the ink pack B which holds black ink, and the other accommodates the ink absorber 17 which absorbs ink. The ink pack B is connected to the recording head 8 of the carriage 7 via the tube T5. The ink absorber 17 is formed of a water-absorbing porous material such as sponge.

Therefore, waste ink and air are sucked by the gear pump GP to flow from the cover member 12 to the first ink tank 9 through the fluid inlet member 15 . The waste liquid is then absorbed by the ink absorber 17 in the first ink tank 9 . The check valve 14 prevents waste ink from returning to the cap member 12 .

The air inlet part 19 of the second ink tank 10 is connected to the air outlet part 18 of the first ink tank 9 via a tube T6. Therefore, the first ink tank 9 and the second ink tank 10 communicate with each other. The second ink cartridge 10 includes a plurality of holder portions defined by corresponding spacers 20 . Each holding portion holds one of ink packs C, M, Y, LC, and LM containing color inks of cyan, magenta, yellow, light cyan, and light magenta, respectively. The ink packs C, M, Y, LC and LM are connected to the recording head 8 of the carriage 7 via tubes T7, T8, T9, T10 and T11, respectively. An opening device 22 is connected to the air outlet part 21 of the second ink tank 10 via a tube T12 for opening the second ink tank 10 when necessary.

Therefore, when the gear pump GP is activated, waste ink and air are sucked from the cover member 12, thereby flowing into the cover member in the order of the cover member 12, the tube T2, the gear pump GP, the tube T3, the check valve 14, and the tube T4. 12. Tube T2, gear pump GP, tube T3, check valve 14 and tube T4. Then, waste ink and air are introduced into the first ink tank 9 . At this stage, the waste ink is absorbed by the ink absorber 17 . Therefore, only air (hereinafter, referred to as “pressurized air”) moves in the first ink tank 9 . Pressurized air then flows from the first ink tank 9 to the second ink tank 10 via the tube T6 and is held by the opening device 22 connected to the tube T12.

In other words, the air pressure in the first ink tank 9 and the air pressure in the second ink tank 10 are constantly kept equal without becoming unbalanced with each other. Therefore, when the gear pump G is activated, the ink packs B, C, M, Y, LC and LM in the first and second ink tanks 9, 10 are pressurized with pressurized air. This causes the ink of the ink packs B, C, M, Y, LC and LM to flow to the recording head 8 of the carriage 7 .

More specifically, in the first embodiment, the gear pump GP of the printer 1 is used as a cleaning pump for applying negative pressure to the cover member 12 and as a pump for pressurizing the ink packs B, C, M, Y, LC, and LM. booster pump. Therefore, when the gear pump GP is activated, the gear pump GP applies a negative pressure to the cap member 12 for sucking waste ink and air, and pressurizes the ink packs B, C, M, Y, LC, and LM for Ink is supplied to the recording head 8 .

The structure of the check valve 14 will now be described in detail with reference to FIGS. 3 and 4 .

As shown in FIG. 3 , the check valve 14 includes: a main body housing 30 ; a diaphragm portion 31 ; a support member 32 ; and a spring member 33 . The main body housing 30 has an upper housing portion 30a and a lower housing portion 30b. An upstream valve chamber portion 34 is defined in an annular shape in the upper housing portion 30a. A downstream valve chamber portion 35 is defined in the lower housing portion 30b in a funnel shape. A valve chamber 36 is defined in the main body housing 30 by the upper housing portion 30a and the lower housing portion 30b joined together.

A connection hole (not shown) for the connection tube T3 and a connection hole 32 for the connection tube T4 are defined in the main body housing 30 of the check valve 14 . The connection hole for the tube T3 communicates with the upstream valve chamber portion 34 via a first passage 38 defined in the main body casing 30 (upper casing portion 30a). The connection hole 37 for the tube T4 communicates with the upstream valve chamber portion 35 via a second passage 39 defined in the main body casing 30 (lower casing portion 30b). This structure allows waste ink and air to flow from the gear pump GP to the valve chamber 36 (the upstream valve chamber portion 34 and the downstream valve chamber portion 35 ) via the tube T3 and the first passage 38 . Then, waste ink and air flow from the valve chamber 36 to the first ink tank 9 via the second passage 39 and the tube T4.

The diaphragm portion 31 is formed of a flexible material such as disc-shaped rubber. To assemble the check valve 14 , the diaphragm portion 31 is received in the valve chamber 36 , the outer circumferential end 40 of the diaphragm portion 31 being fixedly held between the upper and lower housing portions 30 a , 30 b of the main body housing 30 . In this way, diaphragm portion 31 separates upstream valve chamber portion 34 from downstream valve chamber portion 35 in valve chamber 36 . As shown in FIG. 3, this configuration allows the middle portion of the diaphragm portion 31 to reciprocate up and down (towards the upstream valve chamber portion 34 and the downstream valve chamber portion 35). The communication hole 41 extends through the middle portion of the diaphragm portion 31 . The upstream valve chamber portion and the downstream valve chamber portion 34 , 35 communicate with each other via the communication hole 41 . An annular protrusion 42 is formed around the communication hole 41 (in the upstream valve chamber portion 34 ). A cylindrical contact portion 43 protrudes from the upper housing portion 30 a in a manner directly opposite to the protrusion 42 . When kept in close contact with the protrusion 42 , the contact portion 43 blocks the communication hole 41 . By removing a portion of the upper housing portion 30a corresponding to the upstream valve chamber portion 34, the contact portion 43 is formed in a cylindrical shape. This configuration allows the upstream and downstream valve chamber portions 34, 35 to communicate with each other when the diaphragm 31 is deformed downward so that the protrusion 42 separates from the contact portion 43 (towards the downstream valve chamber portion 35). In contrast, when the diaphragm 31 deforms upward (toward the upstream valve chamber portion 34 ) so that the protrusion 42 contacts the contact portion 43 , the upstream valve chamber portion 34 is separated from the downstream valve chamber portion 35 .

From the side corresponding to the downstream valve chamber portion 35 , the support member 32 having a cylindrical shape is fitted into the communication hole 41 of the diaphragm portion 31 . The support member 32 is integral with the diaphragm portion 31 . When the support member 32 is pushed by the spring member 33 , the support member 32 deforms the diaphragm portion 31 upward from the downstream valve chamber portion 35 (to the upstream valve chamber portion 34 ). The through hole 44 is defined by the space surrounded by the support member 32 and communicates with the communication hole 41 . The protrusion 32 a protrudes from the outer side surface of the support member 32 , and the upper side (the end closer to the upstream valve chamber portion 34 ) of the protrusion 32 a contacts the diaphragm portion 31 . This structure allows the support member 32 to be positioned relative to the diaphragm portion 31 when fitted into the diaphragm portion 31 .

A circular recess 45 is defined in the bottom of the downstream valve chamber portion 35 , opposite the support member 32 . The spring member 33 engages the wall of the recess 45 and the outer circumferential surface of the support member 32, and contacts the protrusion 32a. In this way, the spring member 33 is accommodated in the downstream valve chamber portion 35 . The spring member 33 urges the diaphragm portion 31 upward (toward the upstream valve chamber portion 34 ) via the support member 32 . If the pressure difference between the upstream valve chamber portion 34 and the downstream valve chamber portion 35 is equal to or less than the reference value, the spring member 33 deforms the diaphragm portion 31 to cause the protrusion 42 to contact the contact portion 43 . Conversely, if the difference between the pressure in the upstream valve chamber portion 34 and the pressure in the downstream valve chamber portion 35 is greater than the reference value, the spring member 33 is pushed downward (downstream) due to the pressure received from the upstream valve chamber portion 34 via the diaphragm portion 31. The valve chamber portion 35) is deformed.

Therefore, as shown in FIG. 3 , if the difference between the pressure in the upstream valve chamber portion 34 and the pressure in the downstream valve chamber portion 35 is equal to or less than the reference value, the protrusion 42 of the diaphragm portion 31 contacts the contact portion 43 . In this state, the check valve 14 separates the upstream valve chamber portion 34 from the downstream valve chamber portion 35, thereby preventing the corresponding flow of waste ink and air. As shown in FIG. 4a, if waste ink and air flow from the gear pump GP to the check valve 14 in this state, the waste ink is introduced into the upstream valve chamber portion 34, and the upstream valve chamber portion 34 is filled with waste ink. This increases the pressure in the upstream valve chamber portion 34 and thus the difference between the pressure in the upstream valve chamber portion 34 and the pressure in the downstream valve chamber portion 35 increases beyond the reference value. Then, as shown in FIG. 4( b ), the check valve 14 separates the protrusion 42 from the contact portion 43 . This puts the upstream and downstream valve chamber portions 34 , 35 in communication with each other, allowing the flow of waste ink and air from the upstream valve chamber portion 34 to the downstream valve chamber portion 35 . Simultaneously, the waste ink and the air sent to the check valve 14 from the gear pump GP through the pipe T3 pass through the first passage 38, the upstream valve chamber portion 34, the communication hole 41, the through hole 44, the downstream valve chamber portion 35, and the second passage 39. The sequence of the tube T4 flows into the first passage 38, the upstream valve chamber portion 34, the communication hole 41, the through hole 44, the downstream valve chamber portion 35, the second passage 39, and the tube T4. Then, waste ink and air flow into the first ink tank 9 . As shown in Figure 4(c), when the gear pump GP stops and the waste ink and air flow into the first passage 38 is suspended, the pressure in the upstream valve chamber portion 34 drops, while the pressure in the upstream valve chamber portion 34 and the downstream valve chamber The difference between the pressures in the portion 35 becomes equal to or smaller than the reference value. At this stage, the diaphragm portion 31 is deformed upward (toward the upstream valve chamber portion 34 ) by the spring member 33 and pushed upward by the waste ink in the downstream valve chamber portion 35 . This causes the protrusion 42 of the diaphragm portion 31 to contact the contact portion 43 , thereby separating the upstream valve chamber portion 34 from the downstream valve chamber portion 35 . The corresponding flow of waste ink and air is thereby stopped. This prevents waste ink and air from returning from the downstream valve chamber portion 35 to the upstream valve chamber portion 34 . Therefore, waste liquid and air cannot flow to the gear pump GP.

As already described, only when the difference between the pressure in the upstream valve chamber portion 34 and the pressure in the downstream valve chamber portion 35 due to the flow of waste ink and air into the first ink tank 9 is greater than the reference value, the check valve 14 is opened for waste ink and air to flow in the first ink tank 9. More specifically, the printer 1 of the first embodiment flows waste ink and air from the gear pump GP to the first ink tank 9 through the check valve 14 , and sends air as pressurized air to the second ink tank 10 . Thus, the first and second ink tanks 9, 10 are supplied with pressurized air whose pressure is not less than the reference level. The reference level of pressure corresponds to a predetermined value for effectively pressurizing ink packs B, C, M, Y, LC, and LM.

In addition, waste ink and air flowing to the first ink tank 9 through the check valve 14 are prevented from flowing back. This suppresses contamination of the recording head 8 unlike conventional liquid ejection devices. In addition, the pressure drop of the pressurized air flowing into the first and second ink tanks 9, 10 is suppressed.

Hereinafter, the operation of the check valve 14 will be described.

When the gear pump GP of the printer 1 is activated, the gear pump GP sucks waste ink and air from the cover member 12 . Thus, waste ink and air flow into the cover member 12, tube T2, gear pump GP, tube T3, check valve 14 and The tube T4 is introduced into the first ink tank 9. Then, air is sent from the first ink tank 9 to the second ink tank 10 as pressurized air for pressurizing the ink packs B, C, M, Y, LC, and LM. More specifically, the ink packs B, C, M, Y, LC and LM are pressurized. In addition, the pressure drop of the pressurized air is suppressed. When pressurized, the ink packs B, C, M, Y, LC, and LM supply the inks of the corresponding colors to the recording head 8, thereby reliably performing printing.

The first embodiment has the following advantages.

(1) In the first embodiment, the check valve 14 is configured to prevent waste ink and air from returning from the downstream valve chamber portion 35 to the upstream valve chamber portion 34 . This suppresses the backflow of waste ink and air to the gear pump GP. Thus, unlike conventional liquid ejection devices, contamination of the recording head 8 is suppressed. In addition, the pressure drop of the pressurized air flowing into the first and second ink tanks 9, 10 is suppressed, and the pressure of this air is effectively maintained. Printing is thereby reliably performed.

(2) In the first embodiment, the check valve 14 is opened only when waste ink and air flow to the check valve 14 . Therefore, even if the printer 1 is not used for a considerable time and the pressure in the downstream valve chamber portion 35 is equal to the atmospheric pressure, the upstream and downstream valve chamber portions 34, 35 are kept separated from each other. This prevents ink from flowing back to the cover member 12 when, for example, the printer 1 is moved.

(second embodiment)

A second embodiment of the present invention will be described below with reference to FIGS. 5 and 6 .

In the second embodiment, similar to the check valve 14 of the first embodiment, the check valve suppresses the backflow of waste ink and air to the cap member 12 . The check valve of the second embodiment differs from the check valve 14 of the first embodiment in terms of the installation position relative to the frame 2 of the printer 1 . Thus, the configuration of the check valve of the second embodiment is modified accordingly. Therefore, the following description focuses on the differences between the first embodiment and the second embodiment. The same or similar reference numerals are used to designate the same or similar parts of the second embodiment as the corresponding parts of the first embodiment.

As shown in FIG. 5, the gear pump GP is connected to the cover member 50 through a check valve 51 and a tube T13. The first ink tank 9 is connected to the gear pump GP via a tube T14. Similar to the first embodiment, by sealing the nozzle surface 8a by the cap member 50, and activating the gear pump GP for applying negative pressure to the nozzle N, the nozzle N of the nozzle surface 8a is cleaned. Waste ink discharged in this cleaning and air flow into the cover member 50, check valve 51, tube T13, gear pump GP, and tube T14 in this order. T14. Then, waste ink and air are introduced into the first ink tank 9 similarly to the first embodiment. In addition, air as pressurized air is sent from the first ink tank 9 to the second ink tank 10 . This pressurizes the ink packs B, C, M, Y, LC and LM of the first and second ink tanks 9 , 10 , thereby supplying ink to the recording head 8 . In cleaning, the ink supplied to the recording head 8 is discharged from the nozzles N of the recording head 8 to the cap member 50 . More precisely, as long as the cap member 50 seals the nozzle surface 8a, the printer 1 forms a closed circulation system.

Since the check valve 51 is provided in the second embodiment, the check valve 14 between the gear pump GP and the first ink tank 9 is not provided.

The configuration of the cover member 50 and the configuration of the check valve 51 will be described in detail below with reference to FIG. 6 .

As shown in FIG. 6 , a check valve 51 is fastened to the bottom of the cover member 50 , and the check valve 51 is integrally formed with the cover member 50 . The cover member 50 includes a case 52 , a sealing portion 53 and an ink absorber 54 . When viewed from above, the casing 52 forms a thin box-like shape defining a rectangular shape so as to cover the nozzle N of the nozzle surface 8a. An opening 52a is defined in the upper surface of the housing 52 (opposite the nozzle surface 8a). A sealing portion 53 is formed around the opening 52a in a protruding manner. The sealing portion 53 closely contacts the nozzle surface 8a, and is formed of a flexible material such as an elastomer. Similar to the first embodiment, the cap member 50 seals the nozzle N by keeping the sealing portion 53 in close contact with the nozzle surface 8a for covering the nozzle surface 8a with the sealing portion 53 and the housing 52 .

The communication hole 55 extends through the bottom 52 b of the casing 52 and is continuously defined with a cylindrical outlet portion 56 protruding from the bottom of the cover member 50 . The cover member 50 is connected to the check valve 51 via the outlet portion 56 . Therefore, the inside of the cover member 50 communicates with the inside of the check valve 51 through the communication hole 55 . A ring 57 formed of a flexible material such as rubber is fitted in the end closer to the outlet portion 56 of the check valve 51 . When the cap member 50 and the check valve 51 are combined together, the ring 57 prevents waste ink and air from leaking from the combined portion. Through the opening 52 a, the ink absorber 154 formed of a porous body such as sponge is inserted into the case 52 of the cover member 50 so as to be housed in the case 52 . The ink absorber 54 absorbs and holds ink discharged from the nozzles N of the recording head 8, and sends the ink to the check valve 51 through the communication hole 55 as necessary.

The communication hole 58 extends through the upper surface (opposed to the cover member 50 ) of the upper housing portion 30 a of the check valve 51 . With the cover member 50 combined with the check valve 51 , the communication hole 58 connects the inside of the cover member 50 to the upstream valve chamber portion 34 via the communication hole 55 . In the second embodiment, the tube T13 is connected to the connection hole 37 of the check valve 51 .

Therefore, waste ink and air are allowed to flow from the cap member 50 to the tube T13 via the upstream and downstream valve chamber portions 34, 35 of the check valve 51.

More specifically, similar to the first embodiment, if the gear pump GP is activated and the difference between the pressure in the upstream valve chamber portion 34 and the pressure in the downstream valve chamber portion 35 exceeds a reference value, the upstream and downstream valve chambers The parts 34, 35 are connected to each other. Thus, pressurized air is sent to the first ink tank and the second ink tank 9,10. More specifically, although the check valve 51 of the second embodiment is located upstream of the gear pump GP (closer to the cover member 50), as in the first embodiment, pressurized air whose pressure is lower than the reference level is supplied to the second embodiment. One and two ink tanks 9,10. This effectively pressurizes the ink packs B, C, M, Y, LC and LM to supply ink of the corresponding color to the recording head 8 . Printing is thereby reliably performed. As has been described for the first embodiment, the reference level of pressure corresponds to the predetermined value for effectively pressurizing the ink packs B, C, M, Y, LC, and LM.

Furthermore, similar to the check valve 14 of the first embodiment, the check valve 51 prevents ink from returning from the downstream valve chamber portion 35 to the upstream valve chamber portion 34 or from the gear pump GP to the cover member 50 . Therefore, even if the cap member 50 seals the nozzle surface 8a for cleaning the nozzle surface 8a so that the printer 1 forms a closed circulation system, backflow of waste ink and air to the nozzle N through the cap member 50 can be suppressed. The ink meniscus formed in the nozzle N is thus maintained while ink ejection is efficiently performed from the nozzle N. Therefore, printing can be performed further reliably. Furthermore, similarly to the first embodiment, the pressure drop of the pressurized air flowing into the first and second ink tanks 9, 10 is suppressed while the pressure of the air is effectively maintained.

The present invention is not limited to the shown embodiment but may be modified as follows.

Although in the second embodiment, the cover member 50 and the opening valve 13 are not connected to each other, both parts may be connected to each other. In this case, the structure of the cover member 50 is required to be modified as required.

In the first embodiment, the check valve 14 is arranged between the gear pump GP and the first ink tank 9 by connecting the check valve 14 to the tubes T3, T4. However, the check valve 14 may be provided between the first and second ink tanks 9, 10 by connecting the check valve 14 to the tube T6. This allows the check valve 14 to further reliably supply the pressurized air whose pressure is not less than the reference level to the second ink tank 10 .

In the illustrated embodiment, the first ink tank 9 and the second ink tank 10 are provided separately from each other. However, the first and second ink tanks 9, 10 may be integrally formed. In this case, the structure of the printer 1 is required to be modified as necessary.

In the illustrated embodiment, a first ink tank 9 and a second ink tank 10 are provided. However, separate ink tanks can be set for ink packs B, C, M, Y, LC, and LM. In this case, the ink tanks are controlled separately from each other, so that the reliability of the inks held in the ink packs B, C, M, Y, LC, and LM can be improved. Furthermore, by using a plurality of ink tanks, the amount of ink supplied to the recording head 8 is increased. If the ink tank is arranged in this way, the structure of the printer 1 is required to be modified as necessary.

In the illustrated embodiment, an ink absorber 17 is arranged in the first ink tank 9 . However, another ink absorber 17 may be provided in the second ink tank 10 . In this case, even when waste ink enters the second ink tank 10, the ink is absorbed by the ink absorbing material 17 quickly.

In the illustrated embodiment, the first ink tank 9 houses ink pack B, while the second ink tank 10 houses ink packs C, M, Y, LC, and LM. However, the ink pack may be accommodated in any other suitable manner. More specifically, for example, the first ink tank 9 can accommodate ink packs B and C; and the second ink tank 10 can accommodate ink packs M, Y, LC, and LM. Alternatively, the first or second ink cartridge 9, 10 may comprise a further ink pack of the same or a different color as any ink pack originally contained in the ink cartridge 9, 10. In this case, the configuration of the printer 1 is required to be modified as necessary for supplying the inks of these colors to the recording head 8 .

In the illustrated embodiment, the ink ejection device is embodied as a printer 1 . However, the present invention may be realized as any other suitable liquid ejection device. For example, the present invention can be realized as a liquid ejection device that ejects liquid such as electrode materials or color materials used for manufacturing liquid crystal displays, EL displays, and surface emission displays. Alternatively, the present invention can be implemented as a liquid ejection device ejecting liquid bioorganic substances used for manufacturing biochips or a sample ejection device such as a precision pipette. In each of these cases, the structures of the first and second ink tanks 9, 10 may be changed as desired.

Claims (12)

1. A liquid injection device comprising: a liquid ejection head for ejecting liquid; a cap member for receiving waste liquid discharged from the liquid ejection head; a waste liquid box for holding said waste liquid; and a gear pump for sucking the waste liquid from the cover part and introducing the waste liquid into the waste liquid box, It is characterized in that the device further includes a waste liquid backflow suppressing device for suppressing the waste liquid from flowing back to the cover part. 2. The device according to claim 1, wherein the waste liquid backflow suppressing device is arranged between the waste liquid box and the gear pump or between the gear pump and the cover member. 3. The device according to claim 1 or 2, characterized in that the waste liquid backflow inhibiting means is formed by valve means. 4. The device according to claim 3, characterized in that: said device further comprises a liquid holder, which holds said liquid to be sprayed while being pressurized by pressurized air, and Liquid is supplied to the liquid ejection head, wherein: the gear pump generates the pressurized air for pressurizing the liquid holder. 5. A liquid ejection device comprising: a liquid ejection head for ejecting liquid; a liquid holder that holds the liquid to be ejected while being pressurized by pressurized air and supplies the liquid to the liquid ejection head; and a gear pump for generating said pressurized air for pressurizing said liquid holder, It is characterized in that the device shown further comprises air backflow suppression means allowing said pressurized air to be supplied only to said liquid holder. 6. The device according to claim 5, characterized in that the air backflow suppression device is arranged in a region between the liquid holder and the gear pump or upstream of the gear pump. 7. Device according to claim 5 or 6, characterized in that the air backflow suppression means is formed by valve means. 8. A liquid ejection device comprising: a liquid ejection head for ejecting liquid; a cap member for receiving the liquid ejected from the liquid ejection head as waste liquid; a gear pump for sucking the waste liquid and the air from the cover part; and a liquid holder having: a waste liquid holder portion for holding the waste liquid sucked by the gear pump and receiving the air as pressurized air; compressed air is to be supplied to the liquid holding portion of the liquid of the liquid ejection head, It is characterized in that the device further comprises a fluid backflow suppression device for suppressing the backflow of the waste liquid and the pressurized air to the cover part. 9. The device according to claim 8, wherein the fluid backflow suppressing means is arranged between the liquid holder and the gear pump or between the gear pump and the cover member. 10. Device according to claim 8 or 9, characterized in that the liquid backflow inhibiting means is formed by valve means. 11. The device according to any one of claims 4, 7 and 10, wherein said valve means comprises: an inlet section into which at least one of said waste liquid or said pressurized air is introduced; an outlet portion through which the waste liquid or the pressurized air flows to the outside from the inlet portion; and a valve body for connecting the inlet portion and the outlet portion to each other if the pressure of the pressurized air is not lower than a predetermined reference level, and if the waste liquid and the pressurized air From the outlet portion back to the inlet portion, the valve body separates the inlet portion from the outlet portion. 12. The device according to claim 11, characterized in that if the difference between the pressure in the inlet part and the pressure in the outlet part exceeds a predetermined reference value, the valve body of the valve device connecting said inlet portion and said outlet portion to each other, and if said difference between the pressure in said inlet portion and the pressure in said outlet portion is equal to or less than the reference value, all of said valve means The valve body separates the inlet portion from the outlet portion.

Images