Liquid storage container and liquid ejection recording apparatus having the container mounted thereon

A reliable ink cartridge that reduce printing nonconformity even during high speed inkjet-recording with multiple nozzles by alleviating rapid external impact applied from the outside of the ink cartridge. Within a casing of an ink cartridge, a flexible bag forming an ink reservoir is accommodated. Between the surface of the flexible bag where a sheet member is bonded and a wall surface of the casing, a stress damping chamber is provided. The stress damping chamber communicates with the atmosphere outside the ink cartridge via an orifice formed on a wall surface of the casing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ink cartridge for storing ink therein to be fed to an inkjet recording head and an inkjet recording apparatus having the ink cartridge mounted thereon.

2. Description of the Related Art

Various types of ink cartridge have been proposed. An ink cartridge is a liquid storage container storing ink therein for feeding the ink to an inkjet recording apparatus. Ink cartridges are roughly classified into three types as follows.

A first type is a so-called whole sponge type for retaining ink by arranging a capillary material, such as a sponge, within the entire internal space of the ink cartridge. A second type is a so-called whole raw ink type directly storing ink in a bag without using such a capillary material. A third type is a so-called semi-raw ink type in that one half of the ink cartridge is provided with the capillary material while the other half is provided with a raw ink chamber for directly storing ink within a casing.

In order to preferably feed ink to the recording head for ejecting the ink, in any of these types of ink cartridges, a configuration for adjusting holding power of the ink stored in the ink cartridge is important. Since this holding power is for leaving the pressure of an ink ejection part of the recording head negative relative to the atmosphere, the holding power is called a negative pressure.

In the whole sponge type mentioned above, ink is retained due to the characteristics of the capillary material and the negative pressure applied to the ink, so that this type has been adopted in various products.

However, in the whole sponge type, the amount of ink retained in the ink cartridge is small in ratio in comparison with the whole raw type. Also, since the negative pressure level and the flow resistance are increased just before ink is used up, the ink remains within the sponge, so that the available ink amount is smaller than the entire volume of the ink cartridge, i.e., the storing efficiency is small. Thus, a whole raw type ink cartridge is proposed in which a spring member is provided in an ink bag for urging the ink bag so as to maintain the bag at a negative pressure in order to increase the ink capacity per unit volume of the ink cartridge and also to achieve stable ink feeding (Japanese Patent Laid-Open No. H06-198904).

FIG. 6is an exploded view of an ink cartridge having the configuration disclosed in Japanese Patent Laid-Open No. H06-198904, andFIG. 7shows the interior of the ink cartridge being urged so as to maintain it under negative pressure.

An ink cartridge10shown inFIG. 6includes a plastic frame16defining an open space serving as an ink reservoir. Within the open space of the frame16, a pressure regulator30is accommodated for maintaining the interior at a negative pressure. On one side of the open space of the frame16is provided a flexible thin film22bonded to the plastic frame so as to close the one side of the open space. A hard cover plate12is bonded with an adhesive on the thin film22so as to cover it. On the other side of the open space is provided a flexible thin film24bonded to the plastic frame so as to close the open space. A hard cover plate14is bonded with an adhesive on the thin film24so as to cover it. Thereby, a flexible ink reservoir having a pressure regulator30accommodated therein is formed within the ink cartridge10.

A tip portion13of the ink cartridge10is provided with an ink ejection nozzle arranged on the bottom end wall, to which a print head (not shown) is mounted and electrically driven.

The pressure regulator30includes a pair of plates40and50spaced in parallel with each other and urged with a bow spring60in a direction separating each other so as to move into engagement with the thin films22and24forming the flexible ink reservoir, respectively. An ink filter18is provided at a position inside the frame16and corresponding to the tip portion13. The ink filter18is communicated with the ink reservoir by an appropriate porting element and includes an ink outlet communicated with the print head.

Under no stress conditions, the bow spring60is shaped as shown in solid lines ofFIG. 7. When ink is fed outside the ink cartridge10from the ink reservoir, the thin films22and24move close to each other. Along with this movement, the side plates40and50of the pressure regulator30also move gradually so as to approach each other. Thereby, the side plates40and50and the bow spring60move to a mid point as shown by two-dot chain lines ofFIG. 7. At this time, the bow spring60for urging the ink reservoir is compressed, so that the negative pressure level in the ink reservoir is increased.

In the ink cartridge configured as described above, if an external impact is directly transmitted to the thin films forming the ink reservoir, the thin film may be torn, causing ink leakage. This also applies large vibration to the ink stored in the flexible ink reservoir so that the ink supply to the head becomes unstable, which may cause printing nonconformity.

SUMMARY OF THE INVENTION

The present invention is directed to an ink cartridge and an inkjet recording apparatus incorporating the same which prevent printing nonconformity even during high speed inkjet-recording with multiple nozzles by alleviating rapid external impact applied from the outside of the ink cartridge.

Furthermore, the present invention provides an ink cartridge capable of sufficiently feeding ink without affecting the ink supply when the negative pressure level in the ink cartridge is rapidly increased by the increase in the ink supply per unit time from the ink cartridge to the inkjet head along with high speed inkjet-recording with multiple nozzles or by the temporary increase in the ink supply from the ink cartridge during recovery operation of the inkjet head, even when having an alleviation structure for external impact. The present invention also solves the possible problem in that even when having an alleviation structure for external impact, the negative pressure level in the ink cartridge is increased by the increase in ink resistance due to changes in ink physical property (especially in viscosity) so that ink does not flow smoothly.

In one aspect of the present invention, a liquid storage container includes a liquid reservoir adapted to store a liquid therein; a first spring member accommodated within the liquid reservoir and urging the liquid reservoir so as to maintain the interior of the liquid reservoir at a negative pressure; a casing having a wall and accommodating the liquid reservoir therein; a supply port formed on the wall and facilitating supplying the liquid in the liquid reservoir to the outside; and a stress damping unit provided between the liquid reservoir and the wall of the casing, the stress damping unit damping stress applied to the liquid reservoir.

According to the present invention, a reliable ink cartridge and inkjet recording apparatus can be provided, which reduce printing nonconformity even during high speed inkjet-recording with multiple nozzles by alleviating rapid external impact applied from the outside of the ink cartridge.

DESCRIPTION OF THE EMBODIMENTS

Embodiments according to the present invention will be described with reference to the drawings. In the following embodiments, ink is exemplified as a liquid in the ink cartridge. However, the liquid is not limited to ink and may also include a processing liquid for a recording medium in inkjet recording.

First Embodiment

FIG. 1is a sectional view of an ink cartridge according to a first embodiment of the present invention.

An ink cartridge (liquid container)100shown inFIG. 1includes a hard casing110having an interior space and an ink supply port111formed on the wall of the casing110for supplying ink112(shown by reticular lines in the drawing) to the outside.

Within the casing110, a film-like flexible bag107is accommodated for storing the ink112therein. The opening of the flexible bag107is joined onto the wall position where the ink supply port111is formed so as to form an ink reservoir103. A sheet member113is provided on a portion of the flexible bag107opposing the wall position of the casing110where the ink supply port111is formed for flattening the portion. Between the wall position of the casing110where the ink supply port111is formed and the sheet member113, a compression spring105is provided for urging the flexible bag107in a direction expanding the flexible bag107. That is, the compression spring105urges the flexible bag107so as to maintain the interior of the flexible bag107at a negative pressure.

Between the surface of the flexible bag107where the sheet member113is bonded and the wall surface of the casing110, a stress damping chamber104is formed for damping the stress applied to the flexible bag107. The stress damping chamber104and the ink reservoir103are arranged in series in an expansion/contraction direction of the compression spring105. The stress damping chamber104is formed by joining one opening of an elastically flexible cylinder108(such as a bellows, and the flexible cylinder108itself applies no stress to the flexible bag107) on the surface of the flexible bag107where the sheet member113is bonded as well as by joining the other opening on the wall surface of the casing110.

The wall surface where the other opening of the flexible cylinder108is attached is provided with an orifice115formed thereon. The stress damping chamber104, which is an air chamber, is communicated with the atmosphere outside the ink cartridge via the orifice115formed on the wall surface of the casing110. The orifice115allows air to promptly flow in the chamber in accordance with the displacement of the flexible bag107accompanied by ink consumption due to the normal operation of the ink cartridge mounted on a printer. However, if an external impact is applied so as to promptly displace the flexible bag107, the flexible cylinder108is also displaced rapidly along with the displacement of the flexible bag107. At this time, the volume of the stress damping chamber104formed of the flexible cylinder108changes. Due to this change, outside air of the stress damping chamber104may be pulled in or inside air may be extruded. At this time, the orifice115serves as a resistance against the rapid air flow so as to suppress the displacement of the flexible bag107by inhibiting the displacement of the stress damping chamber104. That is, the stress damping chamber104serves as a shock absorber using the resistance during air flow into and out through the orifice115due to the expansion/contraction of the flexible cylinder108.

In the ink cartridge100structured as described above, an external impact applied from the outside of the ink cartridge is attenuated by the stress damping chamber104, so that the impact is not directly transmitted to the flexible bag107forming the ink reservoir103. Thereby, the flexible bag107may not be damaged by the impact so as to prevent ink leakage.

The vibration of ink within the flexible bag107due to an external impact can also be suppressed, so that the ink can be stably supplied to the inkjet head.

Second Embodiment

FIG. 2is a sectional view of an ink cartridge according to a second embodiment of the present invention. Like reference characters designate like components common to the first embodiment.

An ink cartridge200shown inFIG. 2includes the hard casing110having an interior space and the ink supply port111formed on the wall of the casing110for supplying the ink112(shown by reticular lines in the drawing) to the outside.

Within the casing110, the film-like flexible bag107is accommodated for storing the ink112therein. The opening of the flexible bag107is joined onto the wall position where the ink supply port111is formed so as to form the ink reservoir103. The sheet member113is bonded on a portion of the flexible bag107opposing the wall position of the casing110where the ink supply port111is formed for flattening the portion. Between the wall position of the casing110where the ink supply port111is formed and the sheet member113, the compression spring105is provided for urging the flexible bag107in a direction expanding the flexible bag107. That is, the compression spring105urges the flexible bag107so as to maintain the inside of the flexible bag107at a negative pressure.

Between the surface of the flexible bag107where the sheet member113is bonded and the wall surface of the casing110, the stress damping chamber104is formed. The stress damping chamber104and the ink reservoir103are arranged in series in an expansion/contraction direction of the compression spring105.

The structure described above is the same as that of the first embodiment. Whereas, the following configuration is different from that of the first embodiment.

According to the second embodiment, the stress damping chamber104is formed by joining an opening of a flexible bag208on the surface of the flexible bag107where the sheet member113is bonded. The flexible bag208can expand/contract like a bellows.

A sheet member114is bonded on a portion of the flexible bag208opposing the sheet member113of the flexible bag107for flattening the portion. Between the surface of the flexible bag107where the sheet member113is bonded and the sheet member114, a compression spring106is arranged substantially in series with the compression spring105in an expansion/contraction direction. Thereby, the sheet members113and114are urged in a direction in which the sheet members move apart. The stress damping chamber104is communicated with the atmosphere via an air inlet109penetrating the sheet member114and the flexible bag208which is bonded to the sheet member114.

Within the casing110, a shape-memory alloy wire101capable of expanding/contracting by electric energy is arranged so as to surround parts of a bonded structure composed of the flexible bag107and the flexible bag208. Parts of the shape-memory alloy wire101are mechanically fixed on the surface of the flexible bag208where the sheet member114is bonded, while both ends of the shape-memory alloy wire101are connected to an electric contact block102arranged on the outer wall of the casing110where the ink supply port111is formed. In a state of the shape-memory alloy wire101arranged in such a manner, as shown inFIG. 2, the flexible bag208is constrained by the shape-memory alloy wire101in a contracting direction against the repulsive force of the compression spring106.

Since the compression springs105and106are arranged within the flexible bags107and208, respectively, at the center, the shape-memory alloy wire101surrounding the bonded structure composed of the flexible bags107and208is arranged so as to pass through the center of the surface of the flexible bag208where the sheet member114is bonded. By such a manner, when the shape-memory alloy wire101is contracted, the flexible bags107and208can be contracted in a well-balanced state.

The relationship in force (repulsive force and contractive force) among the compression spring105of the ink reservoir103, the compression spring106of the stress damping chamber104, and the shape-memory alloy wire101is as follows.

“the contractive force of the shape-memory alloy wire101>the repulsive force of the compression spring105>the repulsive force of the compression spring106”

Then, operations of components within the ink cartridge according to the embodiment will be described with reference toFIGS. 3A to 3C.

FIGS. 3A to 3Care drawings showing the ink being consumed according to the second embodiment.

When the ink supply port111is opened so as to supply the ink112to the head (not shown) from the state ofFIG. 3A, the ink volume in the ink reservoir103decreases so as to displace the flexible bag107forming the ink reservoir103as shown inFIG. 3B. Along with this displacement, the compression spring105arranged within the ink reservoir103is compressed so that the boundary wall between the ink reservoir103and the stress damping chamber104is moved in the direction of the arrow shown inFIG. 3B. At this time, the compression spring106arranged in the stress damping chamber104is released in compression so as to expand. Air is absorbed into the stress damping chamber104via the air inlet109arranged in the stress damping chamber104, and the volume of the stress damping chamber104increases. Thereby, the total width W of the ink reservoir103and the stress damping chamber104shown inFIGS. 3A and 3Bdoes not change. As a result, the shape-memory alloy wire101arranged so as to surround part of the bonded structure composed of the ink reservoir103and the stress damping chamber104does not slack and maintains the initial state.

From such a state, by electrifying the shape-memory alloy wire101via the electric contact block102, the flexible bag208shrinks due to the contraction of the shape-memory alloy wire101. Thus, the compression spring106arranged within the stress damping chamber104compresses so as to increase its repulsive force. As a result, as shown inFIG. 3C, the boundary wall between the ink reservoir103and the stress damping chamber104moves in the arrow direction so that the negative pressure level in the ink reservoir103is reduced. Because when the shape-memory alloy wire101is operated and the compression spring106is compressed before the compression of the compression spring105so as to decrease the volume of the stress damping chamber104, the impact generated by the contraction of the shape-memory alloy wire101is absorbed by the stress damping chamber104, preventing the ink leakage from the ink reservoir103due to the impact.

The operation timing of the shape-memory alloy wire101is effective when printing with high duty ratio, supplying a large amount of ink in recovery operation, and when the negative pressure level in the ink cartridge is decreased by an increase in ink resistance due to an increase in ink physical properties (viscosity especially) with external environmental factors such as temperature changes. Such situations can be recognized from the printer, so that the shape-memory alloy wire101can be electrified via the electric contact block102with good timing by determining the situation from the printer.

As described above, according to the embodiment, the stress damping chamber104is arranged so as to connect it to part of the ink reservoir103(the flexible bag107) of the whole raw-ink type ink cartridge; the stress damping chamber104is contracted using the shape-memory alloy wire101operated by a drive current applied from the printer so as to increase the repulsive force of the compression spring106arranged in the stress damping chamber104; and by displacing the flexible bag107with the increased repulsive force, the negative pressure level in the ink reservoir103can be reduced. That is, when the negative pressure level in the ink reservoir is rapidly increased, by operating the shape-memory alloy wire101, the negative pressure level can be improved. As a result, ink can be stably supplied, so that a reliable ink cartridge and inkjet recording apparatus that reduce printing nonconformity can be provided. The ink cartridge according to the embodiment is effective against external impact in the same way as in the first embodiment.

The shape-memory alloy wire101according to the embodiment expands/contracts with changing temperature by martensite transformation. As it has a high electric resistance, the shape-memory alloy wire101can easily be heated by electrification. Thus, the wire can be expanded/contracted by controlling the applied current. A product having such properties includes NT Wire for an electric current actuator (model NT-H7-TTR) manufactured by Furukawa Techno Material Co., LTD.

Third Embodiment

FIG. 4is a sectional view of an ink cartridge according to a third embodiment of the present invention. An ink cartridge300according to the embodiment has basically the same configuration and operation as those of the second embodiment, and so description thereof is omitted.

The point in which the third embodiment differs from the second embodiment is that the electric contact block102for electrifying the shape-memory alloy wire101is arranged on a surface different from that of the casing110where the ink supply port111is provided. Thus, the shape-memory alloy wire101is folded to the interior of the casing110at a fulcrum116arranged in the vicinity of the wall of the casing110where the ink supply port111is formed.

According to the embodiment, an electrical defect can be prevented, which might be caused by the adhesion of ink leaked from the ink supply port111for supplying the ink to the exterior by some reason.

Other Embodiments

Then, an inkjet recording apparatus (liquid ejection recording apparatus) according to another embodiment capable of mounting the ink cartridge described above thereon will be described.FIG. 5is an explanatory drawing illustrating an example of the liquid ejection recording apparatus capable of mounting the ink cartridge according to the present invention thereon.

In the recording apparatus shown inFIG. 5, a recording head H1001connected to the ink supply port111of the ink cartridge according to the embodiments described above is replaceably mounted on a carriage1102. On the carriage1102, an electric connection part (not shown) is provided for transmitting a drive signal to each discharge port train via the electric connection part on the recording head H1001.

The carriage1102is guided by a guide shaft1103arranged on an apparatus body so as to extend in a principal scanning direction so that the carriage1102can move back and forth along the guide shaft1103. The carriage1102is driven by a principal scanning motor1104via a driving mechanism such as a motor pulley1105, a driven pulley1106, and a timing belt1107while being controlled in position and movement. The carriage1102is also provided with a home position sensor1130arranged thereon. Thus, the position can be known when the home position sensor1130on the carriage1102passes through the position of a shielding plate1136.

At the position (home position) of the carriage where the home position sensor1130detects the shielding plate1136, a cap1137is arranged for covering the front surface where ink discharge ports of the recording head H1001are formed. The cap1137is used for recovering the recording head by absorbing ink via openings inside the cap by an absorbing element (not shown). The cap1137is moved by a drive force transmitted through gears so as to cover the ink discharge surface. A cleaning blade1138is provided in the vicinity of the cap1137. These capping, cleaning, and absorption recovering are performed for the ink discharge surface of the recording head when the carriage1102is moved to the home position.

Recording media1108, such as printing paper and plastic thin sheets, are separated one by one from an automatic sheet feeder1132(ASF below) by rotating a pick-up roller1131with a feed motor1135via gears. The sheet is further transferred (secondarily scanned) by the rotation of transfer rollers1109so as to pass through a position (printing position) opposing the ink discharge surface of the recording head. The transfer roller1109is rotated by the rotation of an LF motor1134via gears. During the transfer, the determination of whether the sheet is fed and the confirmation of a cue position when the sheet is fed are executed when a recording medium1108passes through a paper end sensor1133. Moreover, the paper end sensor1133is also used for sensing the actual position of the trailing end of the recording medium1108so as to finally determine the present recording position from the trailing end.

The bottom surface of the recording medium1108is supported on a platen (not shown) so as to form a flat printing surface at the printing position. In this case, the discharge surface of the recording head H1001mounted on the carriage1102protrudes downward from the carriage1102so as to be supported between two pairs of the transfer rollers in parallel with the recording medium1108.

The recording head H1001is mounted on the carriage1102so that the lining direction of discharge ports for each discharge port train intersects with the scanning direction of the carriage1102for recording by ejecting liquid from these discharge port trains.

According to the embodiments described above, an electrothermal conversion element is provided for generating thermal energy for ejecting ink. Alternatively, the present invention may incorporate other ink ejection systems such as a system using a vibration element.

The present invention, in addition to general printing apparatuses, may be applied to copying machines, facsimile machines with communication systems, word processors having printers, and industrial recording apparatuses combined with various processing devices. In such printing apparatuses for recording with carriage scanning, to the ink cartridge having scanning vibration applied thereto, the configuration of the present invention is effective such that ink can be stably fed so as to suppress the reduction in printing quality.

This application claims the benefit of Japanese Application No. 2005-101929 filed Mar. 31, 2005, which is hereby incorporated by reference herein in its entirety.