KR100708143B1 - Inkjet image forming apparatus and head maintenance method thereof - Google Patents

Abstract

The disclosed inkjet image forming apparatus includes an inkjet head including a nozzle portion having a plurality of nozzles for discharging ink, a storage container storing a spinning liquid for softening the ink, and sucking the spinning liquid from the storage container and applying the spraying liquid to the nozzle unit. Application means.

Description

Inkjet image forming apparatus and head maintenance method

1 is a perspective view showing an embodiment of an inkjet image forming apparatus according to the present invention.

Figure 2 is a perspective view showing in detail the device for applying the spinning liquid.

3 is a cross-sectional view showing the operation of applying the spinning liquid.

4 is a cross-sectional view showing the wiping operation.

1 is a perspective view showing another embodiment of an inkjet image forming apparatus according to the present invention;

6 is a flowchart of one embodiment of a head maintenance method according to the present invention;

<Description of the symbols for the main parts of the drawings>

10, 10a ... inkjet head 11, 11a ... nozzle part

20 ...... Transfer unit 30 ...... Drive motor

31 ...... Belt 40 ...... Storage Container

50 ...... Sponge 60 ...... Wiper

The present invention relates to an inkjet image forming apparatus and a head holding management method.

In general, an inkjet image forming apparatus refers to an apparatus for forming an image by ejecting ink onto a sheet of paper from an inkjet head (shuttle type inkjet head) reciprocating in a direction perpendicular to a sheet conveying direction (paper width direction). The inkjet head is provided with a nozzle portion having a plurality of nozzles for ejecting ink. In recent years, attempts have been made to implement high-speed printing using an inkjet head (line inkjet head) having a nozzle portion having a length in the main scanning direction corresponding to the width of the paper instead of the shuttle type inkjet head. Such an inkjet image forming apparatus has a fixed inkjet head and only paper is conveyed, so that the driving apparatus is simple and high-speed printing can be realized. In such an inkjet image forming apparatus, the length of the nozzle portion corresponds to, for example, A4, so that the printing margin in the width direction of the paper is about 210 mm without considering the printing margin in the paper width direction.

The ink near the outlet of the nozzle is likely to solidify because it is in direct contact with air. The solidified ink interferes with the ejection of the ink or distorts the direction of the ejected ink. Therefore, a head maintenance process is required to remove the solidified ink by performing the spitting, wiping, and suction processes before or after several pages of printing. .

By the way, when left for a long time without printing, the degree of solidification of the ink is so severe that the spitting is not good. In this case, spitting should be performed after the suction process forcibly removing ink from the nozzle by using the suction device. This preliminary operation for the series of spitting increases the time required for printing. In addition, when the suction step is performed, ink consumption increases. In particular, in the case of a line ink jet head, the number of nozzles is very large, so the amount of ink consumed in the suction process is further increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide an improved inkjet image forming apparatus and a head maintenance management method which can easily perform spitting even when ink solidification is intensified.

An inkjet image forming apparatus of the present invention for achieving the above object comprises an inkjet head having a nozzle portion formed with a plurality of nozzles for ejecting ink; A storage container in which a spinning liquid for softening the ink is stored; And means for sucking the spitting liquid from the storage container and applying the spouting liquid to the nozzle unit.

In one embodiment, the image forming apparatus further comprises a wiper for rubbing the nozzle portion to push the spitting solution into the nozzle.

The head maintenance method of the inkjet image forming apparatus of the present invention for achieving the above object is an inkjet image forming apparatus for printing an image on a paper by using an inkjet head having a nozzle portion having a plurality of nozzles for ejecting ink. A head maintenance method, comprising: an application step of applying ink to a nozzle part to soften ink; And a spouting step of removing the softened ink by ejecting the ink a plurality of times through the nozzle.

In one embodiment, the head maintenance method performs the spitting step after waiting for a predetermined waiting time after performing the coating step.

In one embodiment, in the head maintenance method, when the idle time of the inkjet head does not perform printing is longer than the reference time, after performing the coating step, the nozzle part is rubbed with a wiper to perform the spitting liquid. A wiping operation is pushed into the nozzle.

In one embodiment, the waiting time is set longer as the pause time is longer.

In one embodiment, the spitting step is performed at least after the dash time has elapsed before performing printing.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view showing an embodiment of an inkjet image forming apparatus according to the present invention. 1, the paper 5 is conveyed in the sub-scanning direction S by a pair of rollers (feeding unit) 20 which are engaged with each other and rotated. The inkjet head 10 is provided above the paper 5. The inkjet head 10 prints an image on the paper 5 by injecting ink onto the paper 5 at a fixed position.

The inkjet head 10 of this embodiment is a line inkjet head having a nozzle portion 11 having a length in the main scanning direction M corresponding to the width of the sheet 5. Although not shown in the figure, a plurality of nozzles are arranged in the main scanning direction M in the nozzle unit 11. The inkjet head 10 includes a chamber in communication with a plurality of nozzles and provided with discharge means (for example, a piezo element and a heater) for providing pressure for discharging ink, a flow path for supplying ink to the chamber, and the like. Since the chamber, the discharge means, the flow path and the like are well opened to those skilled in the art, detailed descriptions are omitted.

In order to realize good print quality, the nozzle part 11 should be maintained at an optimum condition for printing. For this purpose, a series of head maintenance procedures such as preheating, spitting, wiping and suction process are performed. When the temperature of the outside air is low, the viscosity of the ink becomes high. Preheating refers to a process of raising the temperature of the ink to lower the viscosity of the ink to an appropriate viscosity for printing. If printing is not performed for a certain time or there is a nozzle that is not used for a certain time during the printing operation, the ink on the nozzle surface is dried to increase the viscosity of the ink, resulting in poor discharge. Spitting refers to a process of removing ink having a higher viscosity by discharging ink several times every fixed time. Depending on the degree of solidification, the spitting process may be performed several times. The wiping process is a process of removing the solidified ink or the ink around the nozzle by rubbing the surface of the nozzle unit 11. In the suction process, when ink is fixed to the nozzle and the nozzle cannot recover to its normal state by the spitting process, or when bubbles are filled in the flow path inside the inkjet head 10, negative pressure is applied to force the ink out through the nozzle. Say fair. In the suction process, a large amount of ink is consumed.

For example, in the case of the shuttle type inkjet head (10a of FIG. 5) having a length of about 0.5 inches, the nozzle portion 11 has an ink consumption of about 1 cc. In the case of 10), since the length of the nozzle part 11 is about 8 inches or more, about 16 cc of ink is consumed by the above processes. Therefore, when using an ink cartridge having a capacity of 20 cc, only about 4 cc is effectively used for printing. This series of processes is basically to remove the ink with a high viscosity of the nozzle surface to lower the viscosity of the ink, so it is necessary to minimize the amount of ink consumed. In particular, in the case of the line inkjet head 10, a large amount of ink is consumed when suction is performed.

The inkjet image forming apparatus of this embodiment is characterized by applying the spitting liquid to the nozzle unit 11 so that the nozzle can be restored to its normal state only by the spitting process without performing the suction process as much as possible. As the spitting liquid, ink and a friendly liquid are used. For example, if the ink is an aqueous ink, water can be used as the spitting solution. In addition, a number of additives may be added to the spitting liquid including surfactants and elements for separating the solidified ink component from the nozzle inner wall surface and the surface of the nozzle unit 11 well.

1 and 2, the storage container 40 in which the spitting fluid is stored is coupled to the belt 31 driven in the main scanning direction M by the driving motor 30. The storage container 40 is provided with an application means for applying the spinning liquid. As an example of the application means, a sponge 50 may be used. The end portion of the sponge 50 is in contact with the nozzle portion 11. The sponge 50 sucks up the spitting liquid of the storage container 40 by capillary action. When the storage container 40 is moved in the main scanning direction M by the driving motor 30 and the belt 31, the sponge 50 applies the spitting liquid to the nozzle part 11 as a whole.

The image forming apparatus may further include a wiper 60. The wiper 60 is in elastic contact with the nozzle unit 11. In this embodiment, the wiper 60 is installed in the storage container 40 together with the sponge 50. The spitting liquid applied by the sponge 50 is mainly buried in the surface of the nozzle part 11. The wiper 60 is for pushing the applied spinning liquid by rubbing the nozzle unit 11 into the nozzle hole. According to this, the solidified ink inside the nozzle can be effectively softened.

In this embodiment, the wiper 60 and the sponge 50 are located side by side in the main scanning direction (M). When the storage container 40 is moved in the A1 direction, as shown in FIG. 3, the sponge 50 is in contact with the nozzle part 11 to apply the spitting liquid to the nozzle part 11. When the storage container 40 is moved in the opposite direction A2, the wiper 60 contacts the nozzle part 11, as shown in FIG. 4, to spray the spitting liquid on the surface of the nozzle part 11. Push it into the hole. At this time, the wiper 60 serves to remove some of the softened ink deposited on the surface of the nozzle unit 11.

The inkjet image forming apparatus according to the present invention is not limited to the above-described embodiment. For example, although not shown in the drawings, the sponge 50, the wiper 60, and the storage container 40 having a width corresponding to the length of the main scanning direction M of the line inkjet head 10 are sub-scanning directions. While moving to (S), the spouting liquid may be applied, pushed into the nozzle hole, or the nozzle part 11 may be cleaned.

Referring to FIG. 5, an inkjet image forming apparatus having a shuttle inkjet head 10a is shown. The inkjet head 10a moves in the main scanning direction M along the shaft 19 and discharges ink onto the paper 5 conveyed in the sub scanning direction S to print an image. The service station 18 is provided with a storage container 40, a sponge (application means) 50, and a wiper 60. In general, the storage container 40 is fixedly installed at the service station 18, and the inkjet head 10a is moved in the main scanning direction M so that the sponge 50 applies the spouting liquid to the nozzle portion 11a. The wiper 60 pushes the spitting liquid into the nozzle hole or wipes the nozzle portion 11a. However, the scope of the present invention is not limited by this, and when the inkjet head 10a arrives at the service station 18, it is stopped at a predetermined position, and the sponge 50 and the wiper have a configuration as shown in FIG. 60, the storage container 40 is moved in the main scanning direction (M) to clean the nozzle portion (11). In addition, the sponge 50, the wiper 60, and the storage container 40 can also be moved in the sub-scanning direction (S).

Now, while looking at the flow chart shown in Figure 6 will be described the head maintenance method according to the above configuration.

The spitting process is performed to bring an unused nozzle into a state suitable for printing when a printing command is input or after several pages of printing. When the spitting process is started, first, the storage container 40 is moved to apply the spitting liquid to the surface of the nozzle unit 11 using the sponge 50 (S3). The spitting liquid is partially buried near the nozzles to soften the solidified ink adhering to the nozzles. Some penetrate some into the nozzle holes. Then, the spitting operation is performed (S7). When a driving signal of a few pulses is sent to the ejection means for ejecting ink, the ink is ejected through the nozzle and the softened ink and the spitting liquid in and around the nozzle hole are pushed together. The nozzle portion 11 is restored to a state suitable for performing printing. The inkjet head 10 performs a printing operation (S8). Since the ink is softened using the spinning liquid before performing the spitting process, the nozzle can be easily restored to a state suitable for printing in a short time.

The spitting operation is preferably performed after applying the spitting liquid to the nozzle unit 11 and waiting for a predetermined time (wait time tw). During this waiting time tw, the spitting liquid softens the solidified ink. Further, the spitting operation is preferably performed just before the printing is performed after the print data has been received from the host computer, for example, to the extent that printing can be performed. Only when the nozzle unit 11 is in the optimum state, printing can be performed immediately, and optimum print quality can be realized. Also in this case, it is preferable that the spitting operation is performed after the waiting time tw has elapsed after applying the spitting liquid to the nozzle unit 11 (S6).

The waiting time tw is set differently according to the idle time ts in which the inkjet head 10 has not performed printing. To this end, when the spitting process is started, the printing pause time ts is first calculated (S1), and the waiting time ts is set based thereon (S2). The idle time ts can be calculated, for example, by counting the clock of a controller (not shown) controlling the image forming apparatus while not performing printing. The longer the pause time ts, the greater the degree of solidification of the ink, so that the waiting time tw is set longer so that the spitting liquid softens the solidified ink. For example, the waiting time tw is set between 0 and 60 seconds depending on the length of the pause time ts. In this way, the nozzle unit 11 can be restored to a state suitable for performing printing, and the time required to start printing can be reasonably set.

If the idle time ts is longer than the set reference time tr (S4), it is effective to perform the wiping operation before performing the spitting operation (S5). The reference time tr can be appropriately set by experiment in consideration of the solidification speed of the ink. In general, there is no need to perform a wiping operation when performing the spitting process between printing, and a wiping operation may be necessary when the printing is not performed for a long time. By the wiping operation, the spitting liquid can effectively penetrate into the nozzle hole, and the solidified ink strongly attached to the nozzle part 11 can be removed from the surface of the nozzle part 11.

Conventionally, in order to restore the nozzle portion to a state suitable for printing, a spitting operation of several hundred to several thousand dots per nozzle was required, but as described above, according to the inkjet image forming apparatus and the head maintenance management method according to the present invention, Since the spitting operation is performed after softening the ink solidified with the liquid, the nozzle part can be restored to a state suitable for printing by several dots of spinning, and the suction process can not be performed at all or at the minimum necessary. . Therefore, the amount of ink consumed in the process for restoring the nozzle portion to a state suitable for printing can be reduced, and the required time can be shortened. In particular, the inkjet image forming apparatus and the head maintenance method according to the present invention are very effective when applied to an inkjet image forming apparatus employing a line inkjet head.

It is to be understood that the invention is not limited to that described above and illustrated in the drawings, and that more modifications and variations are possible within the scope of the following claims.

Claims (7)

An inkjet head having a nozzle portion having a plurality of nozzles for ejecting ink; A storage container in which a spinning liquid for softening the ink is stored; And an application means for sucking up the spitting solution from the storage container and applying the spouting liquid to the nozzle unit. The method of claim 1, And a wiper for rubbing the nozzle part to push the spitting liquid into the nozzle. A head maintenance method of an inkjet image forming apparatus, which prints an image on paper using an inkjet head having a nozzle portion having a plurality of nozzles for ejecting ink, An application step of applying ink to the nozzle part to soften the ink; And a spouting step of removing the softened ink by ejecting the ink a plurality of times through the nozzle. The method of claim 3, And performing said spitting step after waiting for a predetermined waiting time after performing said coating step. The method of claim 4, wherein When the idle time for which the inkjet head does not print is longer than a reference time, after performing the coating step, the jetting part is rubbed with the nozzle to push the spitting solution into the nozzle. How to maintain the head of the device. The method according to claim 4 or 5, And the waiting time is set longer as the idle time is longer. The method according to claim 4 or 5, And said spitting step is performed at least after said waiting time has elapsed before printing is performed.

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