|
(11) | EP 0 732 210 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
|
|
|
|
|||||||||||||||||||
| (54) | Method of ink suction in ink jet printer |
| (57) A method of adjusting an ink suction amount in an ink jet printer includes the steps
of: determining an ink suction amount according to a printing state; and sucking the
ink from a head according to the determination. Therefore, since the ink is sucked
by moving the piston as much as a predetermined distance according to the clogging
state of the nozzle, unnecessary consumption of the ink can be prevented. Simultaneously,
since the piston only moves to the predetermined position, a suction time can also
be curtailed. Thus, the ink cartridge life can be extended, and work efficiency can
be improved as a recovery time to a normal state from the clogged state is reduced. |
[0002] Ink jet printers are described in U.S. Pat. Nos. 4,926,196, 4,970,535, 5,057,134, 5,184,147, 5,296,876, 5,300,958, and 5,325,111, some of which will be described below.
[0003] Of these, U.S. Pat. No. 4,970,535 discloses an ink jet printer, particularly a head cleaner, in which residual ink is removed from a face of a print head of the ink jet printer by using controlled fluid flow, thereby to clean the head. Though having an effect of cleaning the head face, however, the head cleaner is not effective when a nozzle disposed in the head for supplying ink gets clogged with ink residue or foreign substances.
[0004] Another ink jet printer described in U.S. Pat. No. 5,296,876 has an apparatus for controlling the amount of ink supplied through nozzles according to a printing defect degree when the printing defect occurs. Thus, unnecessary consumption of the ink is avoidable. However, this apparatus cannot solve the nozzle clogging problem.
[0005] In U.S. Pat. No. 5,300,958, an apparatus and a method for cleaning a print head are described, where a particular wiper for providing a cleaning solution to the print head to perform cleaning is provided. However, it has no effect on the clogging of a nozzle.
[0006] To solve the nozzle problem, a method of sucking ink by means of pumping is generally employed to open up the blocked nozzle.
[0007] An arrangement of a head, a suction cylinder, and other relating parts in a conventional ink jet printer adopting such a sucking method is schematically illustrated in FIG. 1.
[0008] Referring to the drawing, in the conventional ink jet printer, a head 11 filled with ink for performing print on a recording sheet is provided. The ink is expelled outside head 11 through nozzle holes (not shown) formed on the lower surface 13 of nozzles (not shown) installed inside head 11.
[0009] When head 11 is in a standby position (non-printing position), air may flow in through the nozzle holes or the nozzle holes may be clogged or damaged with foreign substances. To prevent this, head 11 is situated at a home station (not shown) in the non-printing mode, and a cover 14 for capping the nozzle holes is disposed under the home station. From the lower portion of cover 14, a connection pipe 15, a cylinder 16, and an ink residual reservoir 21 are sequentially provided. Accordingly, ink dropped to cover 14 from the nozzle hole flows into cylinder 16 through connection pipe 15 and then into ink residual reservoir 21. Here, the ink is absorbed by an absorbing pad 22 provided inside ink residual reservoir 21. A reference numeral 15v denotes a first valve for preventing a backward flow which is installed in connection pipe 15 to prevent back flow of the ink.
[0010] Meanwhile, when the nozzle hole of head 11 gets clogged with dried ink or foreign substances such as sheet particles or dirt, in the conventional method, a small amount of ink is expelled from head 11 by a sucking action of a piston 17 of cylinder 16 to open up the clogging. That is, when a motor 18 is driven, a piston rod 16r retreats by an action of a pair of gears 19 and 20 which are meshed with each other and installed at each end of a motor shaft 18s and piston rod 16r, respectively. Piston 17 inside cylinder 16 concurrently retreats, and accordingly, the inner space throughout cover 14, connection pipe 15, and cylinder 16 lies in a lower pressure state than the inside of head 11, so that the ink is absorbed through the nozzle hole, outside head 11, into cover 14. Thus, the clogged nozzle hole is cleared up by sucking the ink through the nozzle hole from head 11. Here, motor 18 is controlled by a controller 24 and a motor driver 23.
[0011] A suction system in the ink jet printer adopting the conventional suction method is schematically illustrated in a flowchart of FIG. 2.
[0012] Referring to FIG. 2, when a suction key is input by a user to clear up the clogging of the nozzle in step 31, controller 24 shown in FIG. 1 generates a motor driving signal. Then, motor 18 drives piston 17 from a standby position to move back toward a position C, in step 32. Accordingly, the inside of cylinder 16 enters a low pressure state, and thus, the ink flows into cylinder 16 from head 11. Here, the ink residual within reservoir 21 does not flow upward through a discharging pipe 25 due to a second valve arranged inside the same for preventing a back flow.
[0013] When piston 17 reaches the position C, controller 24 generates the motor driving signal again, and piston 17 returns to the initial standby position, in step 33. Accordingly, the ink inside cylinder 16 is expelled outside cylinder 16 through discharging pipe 25 into reservoir 21. Here, the ink does not flow through connection pipe 15 due to first valve 15v.
[0014] However, in such a conventional ink suction system, a constant amount of ink is always sucked and expelled regardless of a degree of the clogging of the nozzle, thereby causing an unnecessary consumption of the ink. As a result, life of an ink cartridge is curtailed.
[0015] To solve the above problems, the present invention provides a method of adjusting a suction amount of ink in an ink jet printer by which the ink is sucked step by step according to a degree of clogging of a nozzle, thereby preventing unnecessary ink consumption and curtailing time required for ink suction.
[0016] Accordingly, there is provided according to one aspect of the invention a method of adjusting an ink suction amount in an ink jet printer comprising the steps of: determining an ink suction amount according to a printing state; and sucking the ink from a head according to the determination.
[0017] Therefore, since the piston is moved to a predetermined position according to the clogging state of the nozzle to suck the ink into the cylinder, unnecessary consumption of the ink can be prevented. Also, the suction time can be curtailed since the piston is moved to a preset position.
[0018] The above objects and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings in which:
FIG. 1 is a schematic view illustrating an arrangement of a head, a cylinder and other relating parts in a conventional ink jet printer;
FIG. 2 is a flowchart for explaining a process of clearing up the clogging of a nozzle in the conventional ink jet printer;
FIG. 3 is a flowchart for explaining a method of adjusting an ink suction amount in an ink jet printer according to the present invention; and
FIGS. 4 and 5 are flowcharts for explaining methods of adjusting an ink suction amount in an ink jet printer according to other embodiments of the present invention.
[0019] Though there may be various structures for performing a method according to the present invention, an embodiment of the present invention will be described referring to FIG. 3 and the structure shown in FIG. 1 which is also available for the present invention.
[0020] In order to perform the method of adjusting an ink suction amount according to the present invention, the clogging state of a nozzle can be classified into multiple cases, e.g., it can be classified into three cases as in embodiments of the present invention, and the an ink suction amount mode corresponding to each classified case is preset and stored in controller 24.
[0021] Then, a user determines the clogging state of the nozzle from a printed sheet, and inputs a required suction amount mode to controller 24 according to the clogging state of the nozzle. Controller 24 determines whether a suction key is pressed, in step 41. If the suction key is pressed in step 41, the ink suction amount mode is discriminated, in step 42. Here, the user selects and inputs any required one among suction amount modes. Assuming that three suction amount modes are preset as described above, since a system operates in the same fashion with respect to three suction amount modes, the description will be given to only one mode. For example, when the suction amount mode is "a," controller 24 generates a corresponding motor driving signal, and piston 17 being driven by motor 18 is moved to a position "A" in FIG. 1, in step 43. Then, the ink sucked from head 11 flows into cylinder 16. When piston 17 reaches at "A" position, controller 24 generates again the motor driving signal, and piston 17 returns the initial standby position, in step 44. Accordingly, the ink inside cylinder 16 is expelled outside cylinder 16 through discharging pipe 25 into reservoir 21 in FIG. 1.
[0023] In FIG. 4, a flowchart for explaining a method of inputting an ink suction amount value directly to a controller by a user according to another embodiment of the present invention, is shown. The steps 51, 54, and 55 of the flowchart of FIG. 4 are similar to the steps of FIG. 3 and further description will be omitted. After suction key is pressed in step 51, controller 24 requires the input of the suction amount. Then, in this embodiment, a user inputs a value of the required suction amount by selecting the same by himself, in step 53, without selecting one among the preset values.
[0024] In yet another embodiment, a plurality of ink suction mode switches corresponding to the preset ink suction amount are provided on an operation panel and one among the switches is selected by a user so that the method of the present invention can be performed, which is illustrated in a flowchart in FIG. 5.
[0025] Referring to the drawing, the user first recognizes a printing state and confirms a state of clogging of a nozzle. For example, when the clogged degree is determined to be relatively low, the user selects a mode "a" switch among the ink suction amount mode switches. When the suction mode switch is selected in step 61, controller 24 transfers a motor driving signal to motor driver 23, and accordingly motor 18 drives piston 17 so that piston 17 is moved to a "A" position and then stopped, in step 62. Then, controller 24 generates the motor driving signal again, and piston 17 returns to the initial standby position, in step 63. As a result, the amount of sucked ink is restricted to be as much as that corresponding to a piston's displacement between the initial position and the "A" position.
[0026] Meanwhile, when a mode "c" is selected since the clogged degree is relatively high, which signifies a need of a lot of suction ink amount, controller 24 transfers to motor driver 23 a control signal for moving piston 17 to a position "C." Accordingly, when motor 18 is driven by motor driver 23, piston 17 moves to the "C" position and then stops there, in step 66. Then, piston 17 returns to the initial standby position, in step 67, as in a case of selecting the "a" mode.
[0027] Further, when the user determines the clogging state of the nozzle to be a medium state and selects a mode "b," motor driver 23 receives from controller 24 a control signal for moving piston 17 to a position "B." Motor 18 is driven by motor driver 23, and piston 17 moves to the "B" position and stops there, in step 64. Then, piston 17 returns to the initial standby position as in the "a" and "c" modes selection, in step 65. Likewise, the amount of sucked ink in this mode is restricted to be as much as the amount corresponding to a displacement between the initial position and the "B" position.
[0028] As described above, in the methods of adjusting the ink suction amount in the ink jet printer according to the present invention, since the ink is sucked by moving the piston as much as a predetermined distance according to the clogging state of the nozzle, unnecessary consumption of the ink can be prevented. Simultaneously, since the piston only moves to the predetermined position, a suction time can also be curtailed. Thus, the ink cartridge life can be extended, and work efficiency can be improved as a recovery time to a normal state from the clogged state is reduced.
1. A method of adjusting an ink suction amount in an ink jet printer comprising the steps
of:
determining an ink suction amount according to a printing state; and
sucking the ink from a head according to the determination.
2. A method of adjusting an ink suction amount in an ink jet printer as claimed in claim
1, further comprising the steps of:
dividing the clogging state of a nozzle into a plurality of cases, and
storing in a controller an ink suction mode corresponding to each of said plurality of cases.
3. A method of adjusting an ink suction amount in an ink jet printer as claimed in claim
1, wherein said determination of the ink suction amount is done by directly inputting
a required ink suction amount value.
4. A method of adjusting an ink suction amount in an ink jet printer as claimed in claim
1, wherein said determination of the ink suction amount is done by providing a plurality
of ink suction mode switches corresponding to a predetermined ink suction amount on
an operation panel and selecting any one among the same.
5. A suction system for cleaning nozzles of an ink jet printer head, comprising means
for applying suction to draw ink out of the printer head, characterised by control
means arrange to control the suction means to selectively draw a selected one of plural
different amounts of ink out through said head.
6. A system according to claim 5 in which said suction means comprises a piston in a
chamber, and said control means is arranged to draw said piston to a selelected one
of plural different positions in said chamber to control the amount of ink drawn through
said head.