Patent Grant
7997669
This application claims priority from Japanese Patent Applications No. 2008-219204, No. 2008-219205 and No. 2008-219206, which are filed on Aug. 28, 2008, the disclosures of which are herein incorporated by references in their entireties.
1. Field of the Invention
The present invention relates to an inkjet recording apparatus operable to record an image on a recording medium.
2. Discussion of Related Art
JP-2007-105994A discloses an inkjet recording apparatus in which ink is supplied from an ink tank to a recording head via an ink supply tube (see FIG. 1 of the Japanese Publication). In this inkjet recording apparatus, a quantitative pump is provided in a non-end portion of the ink supply tube, so that a predetermined amount of the ink can be forced to flow from the ink tank to the recording head, by activation of the quantitative pump. The quantitative pump is a plunger pump including a plunger which is introduced in a cylinder and which extends to a distal end portion of the cylinder. The predetermined amount of the ink is conveyed by rotation of the plunger about its axis, which is made by a drive unit such as a motor.
In the disclosed inkjet recording apparatus, the above-described plunger has an end portion that is exposed outside the cylinder. It is considered that a motor is connected to the exposed end portion of the plunger. It is further considered that there is a small clearance between an outer circumferential surface of the plunger and an inner circumferential surface of the cylinder, since the plunger has to be rotatable in the cylinder. Therefore, the clearance has to be sealed by a sealing member such as an O-ring, for avoiding leakage of the ink through the clearance. Due to rotation of the plunger, the sealing member is likely to be worn down, and the wear of the sealing member would problematically cause fragments of the worn sealing members, entrance of air through the sealed clearance and leakage of the ink through the sealed clearance.
The present invention was made in view of the background prior art discussed above. It is therefore an object of the invention to provide an inkjet recording apparatus which is capable of causing a predetermined amount of ink to flow toward a recording head while preventing entrance of air into an ink supply conduit and also leakage of the ink from the ink supply conduit.
This object may be achieved according to a principle of the invention, which provides an inkjet recording apparatus including: (a) a recording head configured to eject ink toward a recording medium; (b) an ink supply source; (c) an ink supply conduit interconnecting the recording head and the ink supply source, such that the ink is supplied from the ink supply source to the recording head in an ink supplying direction; (d) a movable body disposed in the ink supply conduit and movable in the ink supply conduit; (e) a moving device configured to move the movable body in the ink supply conduit; and (f) a control device configured to control the moving device, wherein the ink supply conduit includes a small-clearance defining portion in which a small clearance is to be defined between the movable body and an inner surface of the ink supply conduit when the movable body is being positioned in the small-clearance defining portion, and wherein the control device is configured to control the moving device, such that the movable body is moved from a first position located in the small-clearance defining portion, to a second position located in the small-clearance defining portion, whereby the ink within the small-clearance defining portion is caused to flow toward the recording head, the second position being located on a downstream side of the first position in the ink supplying direction.
In the present inkjet recording apparatus, the ink within the small-clearance defining portion, i.e., a predetermined amount of the ink can be supplied to the recording head, by simply moving the movable body from the first position to the second position. As discussed above in BACKGROUND OF THE INVENTION, for example, if the movable body includes an exposed portion exposed outside the ink supply conduit and the movable body is movable by a motor or a cylinder that is to connected to the exposed portion, a clearance between the ink supply conduit and the movable body is required to be sealed by a sealing member that is made of, for example, a rubber. However, due to movement of the movable body, the sealing member is likely to be worn down, and the wear of the sealing member would problematically cause fragments of the worn sealing members, entrance of air through the sealed clearance and leakage of the ink through the sealed clearance. On the other hand, in the present inkjet recording apparatus, it is possible to arrange such that the movable body is movable only within the ink supply conduit without any portion of the movable body being exposed outside the ink supply conduit. This arrangement eliminates necessity of provision of a sealing member, and makes it possible to prevent the above-described problems which would be caused by the wear of the sealing members.
The above and other objects, features, advantages and technical and industrial significance of the present invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings, in which:
Referring to the drawings, there will be described inkjet printers constructed according to embodiments of the invention.
The subtank 3 is provided to temporarily store therein the ink supplied from the ink cartridge 2 via the supply tube 11, and has an upper opening 3a through which its inner space is exposed to an atmosphere. A level of the ink stored in the subtank 3 is detected by, for example, an optical sensor (not shown). In the inkjet printer 1, the supply of the ink from the ink cartridge 2 is controlled based on the detected level of the stored ink, such that the level of the stored ink is held within a range between a maximum level Hmax and a minimum level Hmin.
The subtank 3 is connected to the waste ink tank 5 via a discharge tube 14 having portions in which a valve 22 and a tube pump 25 are provided. Since the inner space of the subtank 3 is exposed to the atmosphere, the ink stored in the subtank 3 is easily dried so that viscosity of the ink is likely to be increased as time passes. In the inkjet printer 1, when the ink viscosity has been considerably increased, a desired amount of the ink is discharged from the subtank 3 to the waste ink tank 5 via the discharge tube 14, and then the ink is supplied to the subtank 3 from the ink cartridge 2. Thus, the old ink is replaced by the new ink.
The subtank 3 is connected also to the inkjet head 4 via a supply tube 12 so that the ink can be supplied from the subtank 3 to the inkjet head 4 via the supply tube 12 in an ink supplying direction. The inkjet head 4 has a plurality of nozzles (not shown), and defines therein an ink passage that is configured to delivery the ink (which has been supplied from the subtank 3 via the supply tube 12) to the plurality of nozzles. The inkjet head 4 is configured to eject the ink through the nozzles to a recording sheet P when the inkjet head 4 is opposed to the recording sheet P which has been conveyed by a conveying mechanism (not shown).
A branch passage, which branches off from the ink passage defined in the inkjet head 4, is connected to the subtank 3 via a return tube 13 as an ink return conduit. The return tube 13 has a portion in which a valve 24 is provided.
In the inkjet printer 1, for example, when the ink supplied to the inkjet head 4 contains air bubbles, a recycle purge operation is carried out for returning the ink containing the air bubbles, to the subtank 3 via the return tube 13. Since the inner space of the subtank 3 is exposed to the atmosphere, the air bubbles contained in the ink are evacuated to the atmosphere. Thus, by carrying out the recycle purge operation, it is possible to prevent the ink containing the air bubbles, from reaching the nozzles of the inkjet head 4.
The supply tube 12 has portions in which a centrifugal pump 26, a quantitative ink supplier 30 and a valve 23 are provided, such that the centrifugal pump 26, quantitative ink supplier 30 and valve 23 are arranged in this order as viewed in the ink supplying direction. That is, the pump 26 and the valve 23 are provided on respective upstream and downstream sides of the ink supplier 30 in the ink supplying direction. The supply tube 12 is sectioned into an upstream-side tube portion 12a and a downstream-side tube portion 12b which are located on respective upstream and downstream sides of the ink supplier 30 in the ink supplying direction. In the present embodiment, the ink supplier 30 cooperates with the supply tubes 11, 12 to constitute an ink supply conduit defining an ink channel space that is surrounded by an inner surface of the ink supply conduit.
The quantitative ink supplier 30 will be described with reference to
As shown in
The tubular portion 31b defines an inner space 34 having a large diameter portion, a transition portion, a small diameter portion and a tapered portion which are arranged in this order of description as viewed in the ink supplying direction, as shown in
The flange 33 is located on an upstream side of the other two flanges 31, 32 in the ink supplying direction. A through-hole 33a having a circular cross section is formed at a center of the flange 33 (see
The flange 32 is interposed between the other two flanges 31, 33 in the ink supplying direction. A through-hole 32a having a circular cross section is formed at a center of the flange 33 (see
As shown in
The spherical body 35 has a diameter, which permits a small clearance to be defined between the spherical body 35 and an inner surface of the tubular portion 31b when the spherical body 35 is being positioned in the downstream-side space 34b as a small-clearance defining portion. In the present embodiment, the small clearance is about 0.1 mm. In a downstream end portion of the above-described small diameter portion of the inner space 34, there is provided a sealing member in the form of an O-ring 36 that is made of an elastic material such as a rubber. The O-ring 36, which is thus provided in the downstream end portion of the small diameter portion of the inner space 34, is fitted in the inner surface of the tubular portion 31b.
The spherical body 35 can be brought into contact with a distal end of the axially extending bar 32c when being positioned in the upstream-side space 34a, namely, when being positioned in a waiting position a as a third position that corresponds to an upstream-side movement end position. The spherical body 35 can be moved from the waiting position a via the movement start position b to a movement termination position c as a second position that corresponds to a downstream-side movement end position. The spherical body 35 can be brought into contact with the O-ring 36 when being positioned in the movement termination position c. It is noted that, more precisely described, broken lines a, b, c in
When the spherical body 35 is being positioned in the waiting position a, an opening as a large clearance is defined between the spherical body 35 and the inner surface of the tubular portion 31b. This opening has a cross sectional area that is much larger than a cross sectional area of the above-described small clearance, which is defined between the spherical body 35 and the inner surface of the tubular portion 31b when the spherical body 35 is being positioned in the downstream-side space 34b as the small-clearance defining portion. Therefore, when the spherical body 35 is being positioned in the waiting position a, an ink-supply-source side portion and a recording-head side portion of the ink supply conduit, which are located on opposite sides of the spherical body 35 in the ink supplying direction, are held in communication with each other through the opening as the large clearance. Thus, the ink-supply-source side portion and recording-head side portion of the ink supply conduit can be held in communication with each other, by simply positioning the spherical body 35 in the waiting position a, without provision of a bypass conduit. The spherical body 35 is kept positioned in the waiting position a, when a printing operation, a recycle purge operation and a massive purge operation are carried out.
When the spherical body 35 has been moved from the waiting position a to the movement start position b, the clearance between the spherical body 35 and the inner surface of the tubular portion 31b becomes small so that it becomes difficult for the ink to flow from the ink-supply-source side portion of the ink supply conduit to the recording-head side portion of the ink supply conduit. When the spherical body 35 is moved from the movement start position b to the movement termination position c, a predetermined amount of the ink stored within the downstream-side space 34b as the small-clearance defining portion is forced to flow toward the inkjet head 4.
When the spherical body 35 has been moved to the movement termination position c, the spherical body 35 is brought into contact with the O-ring 36 so that a fluid tightness between the spherical body 35 and the inner surface of the tubular portion 31b is established by the O-ring 36, thereby reliably stopping flow of the ink toward the inkjet head 4. Thus, the ink can be caused to flow accurately by the predetermined amount toward the inkjet head 4, as a result of the movement of the spherical body 35 from the movement start position b to the movement termination position c in the inner space 34.
As shown in
The magnet 37 as the attracting portion is disposed in proximity to an outer surface of the tubular portion 31b, and is fixed to the endless belt 38. The belt 38 is stretched around the pulleys 41, 42 that are spaced apart from each other in a direction parallel to the ink supplying direction (i.e., leftward direction as seen in
The gear 43 is fixed to an axial end portion of the pulley 42, and meshes with the gear 44 that is connected to the rotary motor 45. That is, when the rotary motor 45 is driven, the gear 44 is rotated and also the gear 43 meshing with the gear 44 is rotated, so that the belt 38 is caused to run as a result of rotation of the pulley 42 that is connected to the gear 43. With the running of the belt 38, the magnet 37 can be moved in directions parallel to the ink supplying direction. Thus, the magnet 37 is reciprocatable between two positions which correspond to the waiting position a and the movement termination position c.
The above-described magnet 37, belt 38, pulleys 41, 42, gears 43, 44 and rotary motor 45 are fixedly disposed in the tray 46 that is fixed to the endless belt 47. The belt 47 is stretched around the pulleys 48, 49 that are spaced apart from each other in a direction perpendicular to the ink supplying direction (i.e., vertical direction as seen in
The gear 50 is fixed to an axial end portion of the pulley 49, and meshes with the gear 51 that is connected to the rotary motor 52. That is, when the rotary motor 52 is driven, the gear 51 is rotated and also the gear 50 meshing with the gear 51 is rotated, so that the belt 47 is caused to run as a result of rotation of the pulley 49 that is connected to the gear 50. With the running of the belt 47, the tray 46 together with the magnet 37, belt 38, pulleys 41, 42, gears 43, 44 and rotary motor 45 that are disposed in the tray 46 is moved in directions parallel to the vertical direction. Thus, owing to the magnet movement mechanism 40, the magnet 37 is reciprocatable in the directions parallel to the vertical direction as well as in the directions parallel to the ink supplying direction.
Referring next to
As shown in
The head controlling portion 61 is configured, when the control device 60 receives print command signals from a personal computer (not shown), to control a head drive circuit 71 such that the ink is caused to be ejected from the inkjet head 4 for thereby performing a printing operation onto the sheet P. Operational states of the valves 21, 22, 23, centrifugal pump 26 and tube pump 25 during the printing operation will be described later.
The valve controlling portion 62 is configured to control the valves 21, 22, 23 such that each of the valves 21, 22, 23 is placed in a selected one of open and close states. The centrifugal pump controlling portion 63 is configured to control a pump driver 72 for driving the centrifugal pump 26. The first tube pump controlling portion 64 is configured to control a pump driver 73 for driving the tube pump 25. The second tube pump controlling portion 65 is configured to control a pump driver 76 for driving the tube pump 27.
The magnet movement controlling portion 66 is configured to control the motor drivers 74, 75 for driving the rotary motors 45, 52, such that the magnet 37 is movable in the directions parallel to the ink supplying direction and also in the directions parallel to the vertical direction, by causing the pulleys 42, 49 to be rotated and thereby causing the belts 38, 47 to run. The spherical body 35 disposed in the inner space 34 of the tubular portion 31b can be attracted by the magnet 35 as the attracting portion. Thus, when the magnet 37 is positioned in a position which is close to the spherical body 35 in the vertical direction and which is opposed to the spherical body 35 in the vertical direction, the spherical body 35 is attracted by the magnet 37 whereby the spherical body 35 is movable together with the magnet 37 in the directions parallel to the ink supplying direction. In the present embodiment, the magnet 37 and magnet movement mechanism 40 cooperate with each other to constitute a part of the moving device that is configured to move the spherical body 35 as the movable body by giving a motive force to the spherical body 35.
There will be next described an operation for supplying the ink from the ink cartridge 2 to the subtank 3. The ink stored in the subtank 3 is gradually reduced as a result of supply of the ink from the subtank 3 to the inkjet head 4. When a level of the ink stored in the subtank 3 has been lowered to a minimum height Hmin as a result of reduction of the ink stored in the subtank 3, the valve 21 is opened under control of the valve controlling portion 62, and the tube pump 27 is activated under control of the second tube controlling portion 65, whereby the ink is sucked from the ink cartridge 2 so as to be supplied to the subtank 3. Then, when the level of the ink stored in the subtank 3 has been elevated to a maximum height Hmax as a result of supply of the ink to the subtank 3, the valve 21 is closed under control of the valve controlling portion 62, and activation of the tube pump 27 is stopped under control of the second tube controlling portion 65, whereby the supply of the ink from the ink cartridge 2 to the subtank 3 is stopped. Thus, the level of the ink stored in the subtank 3 is held within a certain range.
There will be next described an operation for discharging the ink from the subtank 3. The valve controlling portion 62 controls the valves 22, 23, 24 such that the valve 22 is opened while the valves 23, 24 are closed. Meanwhile, the tube pump 25 is activated under control of the first tube pump controlling portion 64, whereby the ink is sucked from the subtank 3 so as to be discharged to the waste ink tank 5 via the discharge tube 14. When a predetermined amount of the ink has been discharged from the subtank 3, the valve 22 is closed under control of the valve controlling portion 62, and activation of the tube pump 25 is stopped under control of the first tube controlling portion 64. Thereafter, the above-described ink supplying operation is carried out for supplying new ink to the subtank 3 from the ink cartridge 2.
There will be described the printing operation that is performed onto the sheet P.
During the printing operation, the spherical body 35 is kept positioned in the waiting position that is located in the upstream-side space 34a. In this instance, the spherical body 35 is attracted by the magnet 37. Therefore, as long as the magnet 37 is not moved, the spherical body 35 is not moved and is fixed in the waiting position. Further, during the printing operation, the valve controlling portion 62 controls the valves 21, 22, 23, 24 (see
There will be described a quantitative purge operation that is carried out, for example, when the inkjet head 4 suffers from clogging of the nozzles that causes failure in the ink ejection, so as to cause a predetermined amount of the ink to be ejected through the nozzles, for thereby recovering from the ink ejection failure.
During the quantitative purge operation, the valve controlling portion 62 controls the valves 21, 22, 23, 24 (see
JP-2007-90639A discloses an arrangement in which a pressure sensor is provided in an ink supply tube so as to detect pressure of the ink in the ink supply tube during activation of a pump. In this arrangement, an amount of the activation of the pump is controlled depending on the detected pressure, such that an amount of ink ejection is kept constant. However, this arrangement leads to increase in manufacturing cost.
JP-2007-105994A discloses an arrangement in which a quantitative pump is provided in a non-end portion of an ink supply tube, so that a predetermined amount of the ink can be forced to flow from an ink tank to a recording head, by activation of the quantitative pump. The quantitative pump is a plunger pump including a plunger which is introduced in a cylinder and which extends to a distal end portion of the cylinder. The predetermined amount of the ink is conveyed by rotation of the plunger about its axis, which is made by a drive unit such as a motor.
In the above arrangement disclosed in JP-2007-105994A, the plunger has an end portion that is exposed outside the cylinder. It is considered that a motor is connected to the exposed end portion of the plunger. It is further considered that there is a small clearance between an outer circumferential surface of the plunger and an inner circumferential surface of the cylinder, since the plunger has to be rotatable in the cylinder. Therefore, the clearance has to be sealed by a sealing member such as an O-ring, for avoiding leakage of the ink through the clearance. Due to rotation of the plunger, the sealing member is likely to be worn down, and the wear of the sealing member would problematically cause fragments of the worn sealing members, entrance of air through the sealed clearance and leakage of the ink through the sealed clearance.
On the other hand, in the present inkjet printer 1, prior to the quantitative purge operation, the magnet 37 is first positioned in a position which is close to the tubular portion 31b in the vertical direction and which is opposed to the waiting position in the vertical direction, as shown in
Then, the quantitative purge operation is carried out by activation of the centrifugal pump 26 under control of the centrifugal pump controlling portion 63. That is, the spherical body 35 is forced, by the activation of the centrifugal pump 26, in the ink supplying direction, so as to be moved from the movement start position to the movement termination position. During the movement of the spherical body 35 from the movement start position to the movement termination position, the ink flows very little via the above-described small clearance between the spherical body 35 and the inner surface of the tubular portion 31b, so that a predetermined amount of the ink stored within the downstream-side space 34b as the small-clearance defining portion is forced to flow toward the inkjet head 4. In this instance, since the valve 24 is closed (see
The spherical body 35 is disposed in the inner space 34 of the tubular portion 31b as a part of the supply tube 12, and is movable only within the inner space 34 without any portion of the spherical body 35 being exposed outside the tubular portion 31b. This arrangement advantageously eliminates necessity of provision of a sealing member, and makes it possible to prevent the above-described problems which would be caused by wear of the sealing members and also to easily convey a predetermined amount of the ink to the inkjet head 4. That is, in the present embodiment, the centrifugal pump 26 also constitutes a part of the moving device that is configured to move the spherical body 35 as the movable body.
The centrifugal pump 26 as a part of the moving device is a pump that is other than a positive-displacement pump. Therefore, if the activation of the centrifugal pump 26 is continued even after the spherical body 35 has been moved to the movement termination position, it is possible to prevent increase of the pressure in the ink-supply-source side portion of the ink supply conduit, i.e., in a portion of the ink supply conduit which is located on an upstream side of the spherical body 35 in the ink supplying direction, namely, which is located on one of opposite sides of the spherical body 35 that is close to the spherical body 26. It is noted that the pump as the part of the moving device does not necessarily have to be a centrifugal pump as long as being a non-positive-displacement pump. It is further noted that there may be provided a sensor capable of detecting that the spherical body 35 has been moved to the movement termination position so that the activation of the pump can be stopped when the spherical body 35 has been moved to the movement termination position. In this modified arrangement, the pump does not necessarily have to be a non-positive-displacement pump but may be a positive-displacement pump.
After the quantitative purge operation, while the activation of the centrifugal pump 26 is being stopped under control of the centrifugal pump controlling portion 63, the rotational motor 45 is driven by the magnet movement controlling portion 66 such that the magnet 37 is moved to substantially the same position as the spherical body 35 in the ink supplying direction, namely, such that the magnet 37 is moved to a position overlapping with the spherical body 35 as seen in the vertical direction that is substantially perpendicular to the ink supplying direction. Then, the rotational motor 52 is driven by the magnet movement controlling portion 66 such that the magnet 37 is moved upwardly toward the flange 31 so as to attract the spherical body 35. Then, the rotational motor 45 is driven by the magnet movement controlling portion 66 such that the magnet 37 is moved from a position opposed to the movement termination position, to a position opposed to the waiting position, for thereby moving the spherical body 35 from the movement termination position to the waiting position.
There will be described the recycle purge operation that is carried out for returning the ink containing the air bubbles, to the subtank 3. During the recycle purge operation, the valve controlling portion 62 controls the valves 21, 22, 23, 24 such that the valves 21, 22 are closed while the valves 23, 24 are opened.
Further, during the recycle purge operation, the spherical body 35 is kept positioned in the waiting position that is located in the upstream-side space 34a. In this instance, since the spherical body 35 is attracted by the magnet 37, the spherical body 35 is not moved and is fixed in the waiting position as long as the magnet 37 is not moved. Then, the centrifugal pump 26 is driven by the centrifugal pump controlling portion 63 such that the ink within the supply tube 12 is forced to flow to the inkjet head 4. The ink flowing into the inkjet head 4 is caused to flow into the branch passage connected to the return tube 13 that is provided with the valve 24, since a flow resistance in the branch passage is reduced by opening of the valve 24 so as to be lower than that in the main ink passage connected to the nozzles. Thus, the ink is returned to the subtank 3 via the return tube 13.
There will be described a massive purge operation that is carried out when the nozzles have to be purged by a larger amount of the ink. As described above, the quantitative purge operation is carried out in case of failure in the ink ejection. However, there is a case where a degree of the ink ejection failure is so serious that the ink ejection failure cannot be sufficiently recovered by the quantitative purge operation, namely, by causing the predetermined amount of the ink within the downstream-side space 34b to be ejected through nozzles. In such a case, the massive purge operation is carried out whereby the nozzles are purged by a larger amount of the ink than in the quantitative purge operation. During the massive purge operation, the valve controlling portion 62 controls the valves 21, 22, 23, 24 such that the valves 21, 22, 24 are closed while only the valve 23 is opened.
Further, during the recycle purge operation, the spherical body 35 is kept positioned in the waiting position that is located in the upstream-side space 34a. In this instance, since the spherical body 35 is attracted by the magnet 37, the spherical body 35 is not moved and is fixed in the waiting position as long as the magnet 37 is not moved. Then, the centrifugal pump 26 is driven by the centrifugal pump controlling portion 63 such that the ink within the supply tube 12 is forced to flow to the inkjet head 4. The ink flowing into the inkjet head 4 is caused to flow into the main ink passage connected to the nozzles, since the valve 24 provided in the branch passage is closed. Thus, a large amount of the ink is ejected through the nozzles of the inkjet head 4.
As described above, in the present inkjet printer 1, in case of the quantitative purge operation and other cases where a predetermined amount of the ink has to be supplied to the inkjet head 4, the spherical body 35 is moved from the movement start position to the movement termination position, for thereby causing the ink to flow toward the inkjet head 4. Further, in the present inkjet printer 1, in case of the recycle purge operation, case of massive purge operation and other cases where the ink has to be supplied to the inkjet head 4 by an amount larger than the predetermined amount, the ink is caused to flow toward the inkjet head 4 by activation of the centrifugal pump 26 while the spherical body 35 is kept positioned in the waiting position.
While the inkjet printer 1 according to the first embodiment has been described, the inkjet printer 1 may be modified as needed. For example, in the above-described first embodiment, the spherical body 35 is moved from the movement start position to the movement termination position, by activation of the centrifugal pump 26. However, the spherical body 35 may be moved from the movement start position to the movement termination position, by moving the magnet 37 from a position opposed to the movement start position, to a position opposed to the movement termination position.
Further, in the first embodiment, the spherical body 35 as the movable body is made of a magnetic material while the attracting portion of the moving device is made of a magnet. However, it is possible to modify such that the spherical body is made of a magnet while the attracting portion of the moving device is made of a magnetic material or a ferromagnetic material.
Further, while the movable body is the spherical body in the first embodiment, the movable body does not necessarily have to be the spherical body but may be a disk-shaped body or otherwise shaped body as long as a small clearance can be defined between the movable body and the inner surface of the tubular portion 31b when the movable body is being positioned in the downstream-side space 34b.
Further, in the first embodiment, when the spherical body 35 is being positioned in the waiting position a, the ink-supply-source side portion and the recording-head side portion of the ink supply conduit, which are located on respective upstream and downstream sides of the spherical body 35 in the ink supplying direction, are held in communication with each other through the opening as the large clearance which is defined in the upstream-side space 34a, as shown in
In the modification shown in
Further, as shown in
Further, the first embodiment may be modified such that the tubular portion 31b extends in a vertically upward direction rather than in a horizontal direction, so that the spherical body 35 is moved from the waiting position to the movement termination position via the movement start position, by causing the spherical body 35 to be moved in the vertically upward direction. In this modification, the spherical body 35 has a specific gravity that is larger than a specific gravity of the ink, whereby the spherical body 35 can be moved, owing to a self-weight of the spherical body 35, from the movement termination position to the waiting position via the movement start position. It is noted that, in this modification, the tubular portion 31b does not necessarily have to extend precisely in an upright direction, but may extend in a diagonal direction as long as the diagonal direction includes a component parallel to the upright direction.
Further, in the above-described first embodiment, the O-ring 36 is provided in the downstream end portion of the above-described small diameter portion of the inner space 34 which is contiguous to the tapered portion of the inner space 34, as shown in
Further, in the above-described first embodiment, the movable body movable within the inner space 34 of the tubular portion 31b is provided by the spherical body 35. However, as shown in
In the modification of
In the modification of
As shown in
In the second embodiment, the moving device, which is configured to move the spherical body 135 as a first movable body, includes a spherical body 110 as a second movable body. The spherical body 110 has a diameter smaller than a diameter of the spherical body 135. The spherical body 110 is made of a magnetic material (ferromagnetic material), and is disposed in the inner space 34 of the tubular portion 31b. The spherical body 110 is located on an upstream side of the spherical body 135 in the ink supplying direction, such that the spherical body 135 can be pushed by the spherical body 110 in a direction toward the recording head 4. The spherical body 110 is movable in directions parallel to the vertical direction together with movement of the magnet 37 which is made by the magnet movement mechanism 40. As shown in
Referring next to
Then, the quantitative purge operation is carried out by activation of the centrifugal pump 26 under control of the centrifugal pump controlling portion 63. That is, the spherical body 135 is forced upwardly, by the activation of the centrifugal pump 26, in the ink supplying direction, so as to be moved upwardly from the movement start position to the movement termination position, as shown in view (b) of
In the inkjet printer according to the second embodiment, the downstream-side tube portion 12b, which is connected to the inkjet head 4, is connected to the upper end portion of the tubular portion 31b. Owing to this arrangement, even if air is introduced into the inner space 34 of the tubular portion 31b, the air can be discharged upwardly from the inner space 34, thereby avoiding the air from being trapped in the inner space 34. It is therefore possible to reliably cause a predetermined amount of the ink to flow from the downstream-side space 34b as the small-clearance defining portion toward the inkjet head 4. After the quantitative purge operation, the spherical body 135 is slowly moved down from the movement termination position to the movement start position, as shown in view (c) of
There will be described various modifications of the second embodiment.
In the modification shown in
As shown in
As shown in
In the inner space 234 of the tubular portion 231b, there is disposed the spherical body 35 as the movable body which is made of a magnetic material (ferromagnetic material) and which is movable only within the inner space 234. The spherical body 35 is movable, together with movement of a magnet 237 that is elongated in the vertical direction, from the waiting position a that is adjacent to the upstream-side tapered portion of the inner space 234, to the movement termination position c that corresponds to the downstream-side movement end position, via the movement start position b that corresponds to the boundary between the above-described transition portion and small-diameter portion of the inner space 234, namely, the boundary between the upstream-side space 234a and the downstream-side space 234b as the small-clearance defining portion.
As shown in
The magnet 237 as the attracting portion is disposed in proximity to the outer surface of the tubular portion 231b, and is fixed to the endless belt 38. The belt 38 is stretched around the pulleys 41, 42 that are spaced apart from each other in a direction parallel to the ink supplying direction (i.e., leftward direction as seen in
The gear 43 is fixed to an axial end portion of the pulley 42, and meshes with the gear 44 that is connected to the rotary motor 45. That is, when the rotary motor 45 is driven, the gear 44 is rotated and also the gear 43 meshing with the gear 44 is rotated, so that the belt 38 is caused to run as a result of rotation of the pulley 42 that is connected to the gear 43. With the running of the belt 38, the magnet 237 is moved in directions parallel to the ink supplying direction. Thus, the magnet 237 is reciprocatable between two positions which correspond to the waiting position a and the movement termination position c.
The above-described magnet 237, belt 38, pulleys 41, 42, gears 43, 44 and rotary motor 45 are fixedly disposed in the tray 46 that is fixed to the endless belt 47. The belt 47 is stretched around the pulleys 48, 49 that are spaced apart from each other in a vertical direction perpendicular to the ink supplying direction. The pulley 48 is located on an upper side of the pulleys 41, 42, and overlaps with the spherical body 35 as seen in the ink supplying direction when the spherical body 35 is being positioned in the waiting position a. Meanwhile, the pulley 49 is located on a lower side of the pulley 48, namely, is located in a position that is more distant, than the pulley 48, from the tubular portion 231b in the vertical direction.
The gear 50 is fixed to an axial end portion of the pulley 49, and meshes with the gear 51 that is connected to the rotary motor 52. That is, when the rotary motor 52 is driven, the gear 51 is rotated and also the gear 50 meshing with the gear 51 is rotated, so that the belt 47 is caused to run as a result of rotation of the pulley 49 that is connected to the gear 50. With the running of the belt 47, the tray 46 together with the magnet 237, belt 38, pulleys 41, 42, gears 43, 44 and rotary motor 45 that are disposed in the tray 46 is moved in directions parallel to the vertical direction. Thus, owing to the magnet movement mechanism 40, the magnet 237 is reciprocatable in the directions parallel to the vertical direction as well as in the directions parallel to the ink supplying direction.
In the present third embodiment, the printing operation, quantitative purge operation, recycle purge operation and massive purge operation are carried out substantially in the same manners as those in the first embodiment, so that descriptions of these operations are not provided herein.
There will be next described a storing operation that is carried out for introducing the ink from the subtank 3 to the inner space 234 of the tubular portion 231b, so as to store the ink in the inner space 234.
While the spherical body 35 is kept positioned in the waiting position, the centrifugal pump 26 is driven under control of the centrifugal pump controlling portion 63 such that the ink is supplied from the subtank 3 to the inner space 234 of the tubular portion 231b. As the ink is supplied to the inner space 234, air bubbles are likely to remain on a downstream side of the spherical body 35 that is positioned in the downwardly convex portion 231c, as shown in view (b) of
There will be described modifications of the third embodiment. While the air bubbles are eliminated by vibrating the spherical body 35 in the third embodiment, the air bubbles may be eliminated in a manner as shown in
While the spherical body 35 is kept positioned in the downstream-side space 234b, the centrifugal pump 26 is driven under control of the centrifugal pump controlling portion 63 such that the ink is supplied from the subtank 3 to the inner space 234 of the tubular portion 231b. When the ink has been stored only in the downwardly convex portion 231c, as shown in view (b) of
Further, as shown in
Further, the third embodiment may be modified such that the tubular portion 231b extends in a vertically upward direction rather than in a horizontal direction, so that the spherical body 35 is moved from the waiting position to the movement termination position via the movement start position, by causing the spherical body 35 to be moved in the vertically upward direction. In this modification, the spherical body 35 has a specific gravity that is larger than a specific gravity of the ink, whereby the spherical body 35 can be moved, owing to a self-weight of the spherical body 35, from the movement termination position to the waiting position via the movement start position. It is noted that, in this modification, the tubular portion 231b does not necessarily have to extend precisely in an upright direction, but may extend in a diagonal direction as long as the diagonal direction includes a component parallel to the upright direction.
Further, in the above-described third embodiment, the O-ring is provided in the downstream end portion of the above-described small diameter portion of the inner space 234 which is contiguous to the downstream-side tapered portion of the inner space 234. However, the provision of the O-ring may be replaced by a modified arrangement in which an entire surface of the spherical body 35 is covered with a rubber or other elastic material having a small thickness, so that the sealing member is provided by the rubber covering the spherical body 35. In this modified arrangement, too, when the spherical body 35 is being positioned in the movement termination position, a fluid tightness between the spherical body 35 and the inner surface of the tubular portion 231b is established by the rubber covering the spherical body 35, thereby reliably stopping flow of the ink toward the inkjet head 4. Thus, the ink can be caused to flow accurately by the predetermined amount toward the inkjet head 4, as a result of the movement of the spherical body 35 from the movement start position to the movement termination position.
Moreover, in the above-described first, second and third embodiments, the movable body (such as the spherical bodies 35, 110, 165 and disk-shaped body 91) which is movable in the tubular portion is made of a magnetic material while the attracting portion of the moving device is made of a magnet. However, it is possible to modify such that the movable body is made of a magnet while the attracting portion of the moving device is made of a magnetic material.
Further, the inkjet recording apparatus according to the invention does not necessary have to be an inkjet printer, and may be even a non-printer apparatus such as facsimile and copying machines.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-219204 | Aug 2008 | JP | national |
| 2008-219205 | Aug 2008 | JP | national |
| 2008-219206 | Aug 2008 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20080018721 | Umeda | Jan 2008 | A1 |
| Number | Date | Country |
|---|---|---|
| S48-76102 | Oct 1973 | JP |
| S59-222357 | Dec 1984 | JP |
| 2007-090639 | Apr 2007 | JP |
| 2007-105994 | Apr 2007 | JP |
| 2008-079428 | Apr 2008 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20100053240 A1 | Mar 2010 | US |
