Patent Application
20090201351
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2007-086886, filed on Mar. 29, 2007, the entire contents of which are incorporated herein by reference.
The present invention relates to a liquid ejection device to which a liquid cartridge is removably mountable.
An inkjet printer is known as a representative example of a liquid ejection device. The inkjet printer includes: a main printer unit including a mounting unit to which an ink cartridge is removably mounted, a head configured to eject ink, and an ink supplying path configured to supply ink to the head; and the ink cartridge removably mounted to the mounting unit of the main printer unit. The ink cartridge has an ink storage space defined therein, an ink supplying port configured to allow the ink to be supplied from the ink storage space to an outside of the ink cartridge, and an atmosphere communicating port configured to introduce an atmosphere into the ink storage space.
In the inkjet printer, air may enter into the ink supplying path even when the ink cartridge is not mounted in the process of mounting or removing the ink cartridge. For example, JP-A-2005-66906 discloses an inkjet printer (main printer unit) including a sub tank opened to the atmosphere and disposed between the ink cartridge and the ink supplying path so that air does not enter into ink supplying path even when the ink in the ink cartridge is used up. This sub tank has an internal space configured to store the ink, an ink inflow port connected to the ink supplying port of the ink cartridge in a state where the cartridge is mounted, an ink outflow port connected to an upstream end of the ink supplying path, and an atmosphere opening port configured to allow the internal space to communicate with the atmosphere.
Generally, when the ink cartridge is mounted to the mounting unit of the inkjet printer, the ink supplying port is connected to the ink supplying path, thereby allowing the ink inside the ink cartridge flow into the ink supplying path. Therefore, a flow path leading from the ink supplying port to ink nozzles of the head through the ink supplying path is filled with the ink at all times. When the ink is ejected from the ink nozzles, ink of an amount corresponding to the ejected amount flows from the ink cartridge to the ink supplying path. When a liquid level in the ink cartridge falls to the ink supplying port, since air introduced from the atmosphere communicating port enters into the ink supplying path, ink cannot be supplied into the ink supplying path. When the ink supplying port is disposed at a bottom surface of an internal space (a surface at the lowest position of the internal space) of the ink cartridge, air does not enter until the ink is used to depletion. However, when the ink supplying port is disposed at a side surface of the internal space of the ink cartridge, the ink cartridge has to be replaced with a new cartridge even though ink remained below the ink supplying port. To resolve this problem, the inventors proposes an ink cartridge including an ink supplying chamber configured to communicate with the ink supplying port, and an ink storage chamber as a separate chamber from the ink supplying chamber, which are partitioned in an internal space of the ink cartridge. These chambers communicate with each other via a communicating port, and the communicating port is positioned lower than the ink supplying port. According to this ink cartridge, even when the ink level falls below the ink supplying port, air does not enter the ink supplying path as long as the ink level is higher than the communicating port, which provides enhanced ink depleting performance.
In order to improve the ink depleting performance and prevent entry of air into the ink supplying path, the present inventors are examining the use of the above-described ink cartridge proposed by the inventors in the inkjet printer main unit as described in JP-A-2005-66906 including the sub tank opened to the atmosphere and disposed between the ink cartridge and the ink supplying path.
Meanwhile, the liquid level in the ink storage chamber 943 does not fall from the state shown in
One aspect of the invention is conceived in view of the above, and has an object to provide a liquid ejection device having a sub tank opened to an atmosphere and into which the liquid from the liquid cartridge flows due to a hydraulic head pressure, with an improved liquid depleting performance of a liquid in a liquid cartridge.
According to an aspect of the invention, there is provided a liquid ejection device comprising: a liquid cartridge having a liquid supply port through which a liquid contained in the liquid cartridge is allowed to be supplied to an outside of the liquid cartridge, a liquid supply chamber defined in the liquid cartridge and configured to communicate with the outside through the liquid supply port, and a first liquid storage chamber defined in the liquid cartridge and configured to communicate with the liquid supply chamber via a first communicating port; and a main unit comprising a liquid ejection head configured to eject the liquid, a mounting unit to which the liquid cartridge is removably mounted, and a sub tank configured to allow fluid communication between the liquid cartridge and the liquid ejection head, wherein the sub tank has: a liquid inflow port connectable to the liquid supply port of the liquid cartridge in a state where the liquid cartridge is mounted to the mounting unit; a liquid outlet port through which the liquid contained in the sub tank is allowed to flow out toward the liquid ejection head; a liquid inflow chamber configured to communicate with the outside of the main unit through the liquid inlet port, the liquid inflow chamber allowing the liquid to be supplied from the liquid cartridge through the liquid inflow port in the state where the liquid cartridge is mounted to the mounting unit; a second liquid storage chamber configured to communicate with the liquid inflow chamber through a second communicating port and to store the liquid supplied from the liquid inflow chamber, the liquid stored in the second liquid storage chamber being allowed to flow out to the liquid ejection head through the liquid outflow port; and an atmosphere opening port configured to allow the second liquid storage chamber to communicate with an atmosphere, and wherein the first communicating port, the second communicating port, and the liquid outflow port are positioned lower than the liquid supply port in the state where the liquid cartridge is mounted to the mounting unit.
According to another aspect of the invention, there is provided a liquid ejection device to which a liquid cartridge is removably moutable, the liquid cartridge having a liquid supply port through which a liquid contained in the liquid cartridge is allowed to be supplied to an outside of the liquid cartridge, said liquid ejection device comprising; a liquid ejection head configured to eject the liquid; a mounting unit to which the liquid cartridge is removably mountable; and a sub tank configured to allow fluid communication between the liquid cartridge and the liquid ejection head in a state where the liquid cartridge is mounted to the mounting unit, wherein the sub tank has: a liquid inflow port connectable to a liquid supply port of the liquid cartridge in the state where the liquid cartridge is mounted to the mounting unit; a liquid outflow port through which the liquid contained in the sub tank is allowed to flow out toward the liquid ejection head; a liquid inflow chamber configured to communicate with the outside of the sub tank through the liquid inflow port, the liquid inflow chamber allowing the liquid to be supplied from the liquid cartridge through the liquid inflow port in the state where the liquid cartridge is mounted to the mounting unit; a second liquid storage chamber configured to communicate with the liquid inflow chamber through a second communicating port and to store the liquid supplied from the liquid inflow chamber, the liquid stored in the second liquid storage chamber being allowed to flow out to the liquid ejection head through the liquid outflow port; and an atmosphere opening port configured to allow the second liquid storage chamber to communicate with an atmosphere, and wherein the second communicating port and the liquid outflow port are positioned lower than the liquid supply port in the state where the liquid cartridge is mounted to the mounting unit.
Embodiments according to the present invention will be described with reference to the drawings.
An image recording unit 16 is disposed at the printing region 15. A platen 17 having larger size than a sheet is disposed below the image recording unit 16. A conveying roller 18 and a pinch roller 19 are disposed at an upstream side of the image recording unit 16 with respect to the conveying path 13 and configured to nip a recording sheet 12 fed from the sheet feeding tray 6 and convey the sheet onto the platen 17. A sheet discharging roller 20 and a pinch roller 21 are disposed at a downstream side of the image recording unit 16 and configured to nip the recording sheet 12 on which printing has been performed and convey the sheet to the sheet discharging tray 7 (see
The image recording unit 16 includes: an inkjet head 22 (liquid ejection head) of piezoelectric driven type which ejects ink (liquid) toward the platen 17 from a plurality of nozzles: a buffer tank 23 capable of storing the ink to be supplied to the inkjet head 22; a head control board 24 configured to perform drive control of the inkjet head 22; and a carriage 25 on which these elements are mounted. The buffer tank 23 is connected to a sub tank 27, as described later, via an ink supplying tube 26. The ink may be directly supplied from the ink supplying tube 26 to the inkjet head 22 without providing the buffer tank 23. The main tank mounting unit 28 is disposed at a position adjacent to the sub tank 27. The opening/closing cover 8 is attached to the main tank mounting unit 28. The main tank mounting unit 28 is provided with a remaining amount detecting sensor 30 that optically detects a remaining ink amount in the main tank 29 in a state where the main tank 29 is mounted.
The remaining amount detecting sensor 30 is connected to a controller 31. The controller 31 is configured to perform the task of detecting the remaining ink amount in the main tank 29, and in addition, the controller 31 is configured to execute operation control of ink ejection from the inkjet head 22, feeding and discharging the recording sheet 12, and various other tasks of the inkjet printer 3. The controller 31 includes a CPU (central processing unit), a ROM configured to store program executed by the CPU and data used in the program, a RAM configured to temporarily store data during execution of a program, a rewritable EEPROM or other memory, an input/output interface connectable to external devices such a personal computer 11, etc. The operator can transmit image information to be recorded by the inkjet printer 3 to the controller 31 by use of the personal computer 11, and receive information on remaining ink amount from the controller 31.
As shown in
A sensor arm 53 is swingably supported by a supporting portion 52 in the interior of the main tank 29. A float portion 55 capable of floating on a liquid surface of the ink is disposed at one end of the sensor arm 53, and a blocking portion 54 is disposed at the other end of the sensor arm 53. In addition, at a sub tank 27 side portion of the main tank 29, a recess 42 is formed continuously to the first ink storage chamber 43. In a state where the main tank 29 is mounted to the main tank mounting unit 28, the recess 42 is sandwiched between a light emitting element and a light receiving element of the remaining amount detecting sensor 30, Two light transmitting portions 51 formed of a semitransparent material enabling transmission of light from the light emitting element are disposed at both side walls of the recess 42. When the remaining ink amount in the first ink storage chamber 43 is high, the blocking portion 54 contacts a bottom surface of the recess 42 and swinging of the sensor arm 53 is thereby restricted. In this state, the blocking portion 54 is positioned between both light transmitting portions 51 so that the light emitted from the light emitting element does not reach the light receiving element, and a detection signal indicating that an adequate amount of ink is left is input into the controller 31. When the remaining ink amount inside the first ink storage chamber 43 becomes low, the float portion 55 falls in accordance with the falling of the liquid level and the blocking portion 54 retreats out of the recess 42. In this state, the light from the light emitting element is transmitted through the light transmitting portions 51 and reaches the light receiving element, and a detection signal indicating that the remaining ink amount has decreased to a predetermined value is input into the controller 31.
An opening 60 and a tubular valve chamber 61 continuous with the opening 60 are disposed at an upper portion of the surface of the main tank 29 opposing the sub tank 27. An annular sealing member 62 is disposed at the opening 60, and an atmosphere opening port 62a is formed at a center of the sealing member 62. The valve housing chamber 61 extends from the opening 60 toward inside the main tank 29, and an atmosphere opening valve 63 is housed in the valve housing chamber 61. The atmosphere opening valve 63 includes: a rod portion 63a that penetrates through the atmosphere port 62a and protrudes toward the sub tank 27 side; and a flange portion 63b that projects in outward radial directions from an inner end portion of the rod portion 63a. The atmosphere opening valve 63 is urged so that the flange portion 63b contacts the sealing member 62 and thereby seals the atmosphere opening port 62a. A groove portion 63c is disposed along a direction of extension of the rod portion 63a, and in a state where the flange portion 63b is separated from the sealing member 62, the valve housing chamber 61 is open to an atmosphere via the groove portion 63c. A communication port 64 is formed at an inner surface of the valve housing chamber 61, and the valve housing chamber 61 is brought into fluid communication via the communication port 64 with an air layer formed at an upper portion of the first ink storage chamber 43.
As shown in
In addition, in the sub tank 27, a flow path wall 74 vertically extends downward from the upper wall portion 71 at a position opposite the ink inflow port 73a. The flow path wall 74 partitions the lower region 70a into an ink inflow chamber 81 and an ink outflow chamber 82. The ink inflow port 73a provided at the ink inflow chamber 81, and vertical communicating port 71a and the ink outflow port 76a are provided at the ink outflow chamber 82. The two chambers 81 and 82 communicates with each other through a second communicating port 83 that is formed in the vicinity of a flush bottom surface 79 of both chambers 81 and 82. The second communicating port 83 is formed as a slit extending between a lower end of the flow path wall 74 and the bottom surface 79.
As shown in
When ink is ejected by the inkjet head 22 in this state, because ink of an amount corresponding to the ejected amount flows from the second ink storage chamber 85 to the ink supplying tube 26, the liquid levels in the first and second ink storage chambers 43 and 85 fall while being matched in height. In addition, in the sub tank 27, after the liquid level in the second ink storage chamber 85 falls to the height position of the vertical communicating port 71a, the liquid level in the ink inflow chamber 81 stops falling due to the effect of the flow path wall 74 and only the liquid level in the second ink storage chamber 85 (ink outflow chamber 82) falls further. Meanwhile, in the main tank 29, after the liquid level in the first ink storage chamber 43 falls to the height position of the ink supplying port 50a, only the liquid level within the first ink storage chamber 43 falls further, while the interior of the valve housing chamber 45 is kept filled with ink. The liquid levels in the first and second ink storage chambers 43 and 85 then pass below the height position of the ink supplying port 50a and reach an upper end position of the first communicating port 48a as shown in
When the ink is ejected by the inkjet head 22 in this state, the ink stored in a space above the ink supplying port 50a in the valve housing chamber 45 and in a space above the ink inflow port 73a in the ink inflow chamber 81 is consumed. Thereafter, as shown in
When the ink is ejected by the inkjet head 22 in this state, the ink inside the main tank 29 cannot be used and only the liquid level in the ink inflow chamber 81 falls. The ink inside the sub tank 27 can be used until the liquid level therein falls to an upper end position of the ink outflow port 76a as shown in
According to the configuration described above, the inkjet printer 3 (printer main unit 3A) includes the sub tank 27 that is opened to the atmosphere through the atmosphere communicating port 78, thereby the atmosphere communication port 76 allows air entered at the mounting of the main tank 29 to be released. In addition, the ink storage space 70 of the sub tank 27 has the ink inflow chamber 81 with the ink inflow port 73a, and the second ink storage chamber 85 with the ink outflow port 76a, and the second ink storage chamber 85 communicates with the ink inflow chamber 81 through the second communicating port 83. Since the second communicating port 83 and the ink outflow port 76a are positioned lower than the first communicating port 48a, the liquid level in the first ink storage chamber 43 can be lowered to the upper end position of the first communicating port 48a. The inkjet printer 3 (printer main unit 3A) can be provided with good ink depletion performance.
In addition, since the upper end position of the ink outflow port 76a is formed lower than the upper end position of the second communicating port 83, the ink depletion performance in the sub tank 27 can be improved. Furthermore, since the second communicating port 83 is positioned in the vicinity of the bottom surface 79 of the sub tank 29, the ink depletion performance in the sub tank 27 can likewise be improved.
The main tank 29 is removably mountable to the main tank mounting unit 28 of the printer main unit 103A in the second embodiment as well. When a new main tank (new liquid cartridge) is mounted to the main tank mounting unit 28, the ink stored in the first ink storage chamber 43 flows into the second ink storage chamber 85 via the valve housing chamber 45 and the ink inflow chamber 81. The liquid level in the first ink storage chamber 43 thereby falls, while the valve housing chamber 45 is kept being filled with ink. In this state, the ink inflow chamber 81 becomes filled with ink, the liquid level in the second ink storage chamber 85 rises, and the liquid levels in the first and second ink storage chambers 43 and 85 become matched in height as shown in
When the ink is ejected by the inkjet head 22 in this state, the ink stored in the space above the ink supplying port 50a in the valve housing chamber 45 and in the space above the ink inflow port 73a in the ink inflow chamber 81 is consumed. Thereafter, as shown in
When the ink is ejected by the inkjet head 22 in this state, the ink inside the main tank 29 cannot be used and the liquid level in the ink inflow chamber 81 falls to a lower end position of the second ink communicating port 183. The ink stored in the sub tank 127 (ink outflow chamber 82) can be used until the liquid level therein falls to the upper end position of the ink outflow port 76a as shown in
Accordingly, the liquid level in the first ink storage chamber 43 can be lowered at least lower than the ink supplying port 50a and the ink depletion performance is improved with the second embodiment as well.
The scope of the present invention is not limited to the first and the second embodiments, and the present invention may include various modification of the inkjet printer including the first communicating port, the second communicating port, and the ink outflow part which are positioned lower than the ink supplying port (ink inflow port). Also, although in the first and second embodiments, the atmosphere opening port 78 is open at all times, the present invention is not limited thereto, and a valve configured to selectively open and close the atmosphere opening port 78 may be provided and may be opened and closed as necessary. For example, the valve closes when the main tank 29 is not mounted to the main tank mounting unit 28 and opens when the main tank 29 is mounted. Also, although the liquid ejection device was described as being an inkjet printer, the present invention can be applied to other liquid ejection deices in which a liquid is supplied from a cartridge. Further, although the second communicating port 83 is positioned lower than the first communicating port 48a in the above embodiments, the second communicating port 83 may be positioned at the same height or lower than the first communicating port 48a.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007086886 | Mar 2007 | JP | national |
