CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2019-0089285 filed on Jul. 24, 2019 in the Korean Intellectual Property Office (KIPO), the contents of which are herein incorporated by reference in its entirety.

BACKGROUND

1. Field

Example embodiments of the invention relate to a method of maintaining an ink jet head and a printing method using an ink jet head. More particularly, example embodiments of the invention relate to a method of maintaining an ink jet head by exactly determining a replacement time of an ink jet head, and a printing method using a suitable ink jet head.

2. Related Technology

To manufacture a display device such as an organic light emitting display device, a printing process for coating chemical liquid on a substrate using an ink jet head capable of discharging the chemical liquid by an ink jet method. Here, the ink jet head is directly related to the printing quality on the substrate so that the ink jet head is replaced when the performance of the ink jet head is deteriorated. Such replacement time of the ink jet head is generally determined depending on the manuals provided by the manufacturers.

The ink jet head is replaced with new ink jet head according to the manuals even though the ink jet head maintains good performance such that the economics and efficiency of the manufacturing apparatuses including the ink jet head can be reduced. Further, the ink jet hear is not replaced when the replacement time of the ink jet head by the manuals is not come even though the performance of the ink jet head is deteriorated. Therefore, the quality and reliability of the display device may be decreased by the ink jet head.

SUMMARY

It is one object of the invention to provide a method of maintaining an ink jet head capable of exactly determining the replacement time of the ink jet head.

It is another object of the invention to provide a printing method using an ink jet head capable of exactly forming desired pixels on a substrate.

According to an aspect of the invention, there is provided a method of maintaining an ink jet head. In the method of maintaining an ink jet head, discharging numbers of the chemical liquid discharged from the ink jet head onto an object may be identified. A cumulative discharging number of the chemical liquid from the ink jet head may be calculated. The cumulative discharging number of the chemical liquid may be compared with a previously set limit discharging number of the ink jet head. A replacement time of the ink jet head may be determined based on the comparison of the cumulative discharging number and previously set limit discharging number.

In example embodiments, the discharging numbers of the chemical liquid may be obtained by counting operating numbers of piezoelectric elements of the ink jet head.

In example embodiments, the cumulative discharging number of the chemical liquid may be calculated by accumulatively counting the operating numbers of the piezoelectric elements of the ink jet head.

In example embodiments, the determining of the replacement time of the ink jet head may be performed if the cumulative discharging number of the chemical liquid exceeds the previously set limit discharging number.

In the determining of the replacement time of the ink jet head according to some example embodiments, it may be determined whether the ink jet head is continuously usable or not.

In the determining of the replacement time of the ink jet head according to some example embodiments, the ink jet head may be replaced with a new ink jet head if the ink jet head is not continuously usable. Alternatively, the previously set limit discharging number of the ink jet head may be reset if the ink jet head is continuously usable.

According to another aspect of the invention, there is provided a printing method using an ink jet head. In the printing method using an ink jet head, a chemical liquid may be discharged onto a substrate from a plurality of nozzles of the ink jet head. Discharging numbers of the chemical liquid from the plurality of nozzles may be identified. Cumulative discharging numbers of the chemical liquid from the plurality of nozzles may be calculated. The cumulative discharging numbers of the chemical liquid may be compared with previously set limit discharging numbers of the plurality of nozzles. A replacement time of the ink jet head may be determined if the cumulative discharging number of the chemical liquid exceeds the previously set limit discharging number.

In example embodiments, the discharging numbers of the chemical liquid may be obtained by counting operating numbers of a plurality of piezoelectric elements of the ink jet head corresponding to the plurality of nozzles, respectively.

In example embodiments, the cumulative discharging numbers of the chemical liquid may be calculated by accumulatively counting the operating numbers of the plurality of piezoelectric elements.

In the determining of the replacement time of the ink jet head according to some example embodiments, it may be determined whether the ink jet head is continuously usable or not.

In the determining of the replacement time of the ink jet head according to some example embodiments, the ink jet head may be replaced with a new ink jet head if the ink jet head is not continuously usable. Alternatively, the previously set limit discharging numbers of the plurality of nozzles may be reset if the ink jet head is continuously usable.

According to still another aspect of the invention, there is provided a printing method using an ink jet head including a plurality of nozzles and a plurality of piezoelectric elements. In the printing method using an ink jet head, a chemical liquid may be discharged onto a substrate from the plurality of nozzles. Discharging numbers of the chemical liquid from the plurality of nozzles may be identified. Cumulative discharging numbers of the chemical liquid from the plurality of nozzles may be calculated. The cumulative discharging numbers of the chemical liquid from the plurality of nozzles may be adjusted if the cumulative discharging numbers of the chemical liquid from the plurality of are different. A replacement time of the ink jet head may be determined if the cumulative discharging numbers of the chemical liquid from the plurality of nozzles exceed previously set limit discharging numbers of the plurality of nozzles.

In the adjusting of the cumulative discharging numbers of the chemical liquid from the plurality of nozzles according to example embodiments, the discharge of the chemical liquid from a nozzle of the plurality of nozzles having a relatively small cumulative discharging number of the chemical liquid may be stopped, and the chemical liquid may be discharged onto the substrate from a nozzle of the plurality of nozzles having a relatively large cumulative discharging number of the chemical liquid after moving the nozzle of the plurality of nozzles having the relatively large cumulative discharging number of the chemical liquid over a discharging point of the substrate corresponding to the nozzle of the plurality of nozzles having the relatively small cumulative discharging number of the chemical liquid.

In example embodiments, the discharging numbers of the chemical liquid from the plurality of nozzles may be obtained by counting operating numbers of the plurality of piezoelectric elements corresponding to the plurality of nozzles, respectively. Additionally, the cumulative discharging numbers of the chemical liquid from the plurality of nozzles may be calculated by accumulatively counting the operating numbers of the plurality of piezoelectric elements.

In the determining of the replacement time of the ink jet head according to example embodiments, the ink jet head may be replaced with a new ink jet head if the ink jet head is not continuously usable, or the previously set limit discharging numbers of the plurality of nozzles may be reset if the ink jet head is continuously usable.

In example embodiments, before the replacement time of the ink jet head is determined, the cumulative discharging numbers of the chemical liquid from the plurality of nozzles may be compared with the previously set limit discharging numbers of the plurality of nozzles.

In the comparing of the cumulative discharging numbers of the chemical liquid from the plurality of nozzles with the previously set limit discharging numbers of the plurality of nozzles according to example embodiments, it may be identified whether the cumulative discharging numbers of the chemical liquid from the plurality of nozzles exceed the previously set limit discharging numbers of the plurality of nozzles, or not.

In some example embodiments, if a cumulative discharging number of the chemical liquid from one nozzle of the plurality of nozzles exceeds a previously set limit discharging number of the one nozzle, and a cumulative discharging number of the chemical liquid from another nozzle of the plurality of nozzles exceeds a previously set limit discharging number of the another nozzle, the discharge of the chemical liquid from the one nozzle may be stopped and the chemical liquid may be discharged onto the substrate from the another nozzle after moving the another nozzle over a discharging point of the substrate corresponding to the one nozzle.

In some example embodiments, the ink jet head may be replaced with a new ink jet head if cumulative discharging numbers of the chemical liquid from nozzles of the plurality of nozzles more than predetermined nozzles exceed previously set limit discharging numbers of the nozzles.

According to example embodiments, the replacement time of the ink jet head may be determined based on the cumulative discharging number of the chemical liquid from the ink jet head and the previously set limit discharging number of the ink jet head such that the efficiency of the manufacturing line including the ink jet head may be enhanced. Additionally, the replacement time of the ink jet head may be exactly determined in the printing method using the ink jet head so that the desired pixels of the display device may be precisely formed on the substrate. Moreover, the ink jet head may be economically maintained since the replacement of the ink jet head may be determined after the continuous use of the ink jet head is decided even though the cumulative discharging number of the chemical liquid exceeds the previously set limit discharging number.

