CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2018-0161531, filed on Dec. 14, 2018, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND

1. Field

The technical field relates to an inspection apparatus for defect inspection of a display panel and a method of driving the inspection apparatus.

2. Description of the Related Art

In general, a display panel (e.g., a display cell) for a liquid crystal display includes a lower substrate, an upper substrate facing the lower substrate, and a liquid crystal layer interposed between the lower substrate and the upper substrate. The lower substrate has a pixel area and a peripheral area to which a driving signal for driving the pixel area is applied.

The pixel area includes a data line extending in a first direction and a gate line extending in a second direction and crossing the data line and a pixel electrode connected to the gate line and the data line. The peripheral area includes a first driving chip pad on which a driving chip for providing a data signal is mounted, and a second driving chip pad on which a driving chip for providing the gate signal is mounted.

After performing a liquid crystal injection process, the display panel performs a vision inspection process for checking the electrical and optical operation states. The vision inspection process includes a mura correction process for correcting a mura (e.g., a mura effect) of the display panel.

The vision inspection process generally converts a reference gray level (e.g., a reference gray or gray level of a grayscale) displayed on the display panel to an electrical signal through an industrial CCD (Charge-Coupled Device) camera. The CCD camera converts a reference gray level exposed to a charge-coupled device into an electrical signal. The vision inspection process uses the reference gray level signal to calculate a correction value for correcting a vision defect of a display panel such as a mura.

Recently, due to process dispersion (or manufacturing disparity) by a high resolution display and a pixel structure manufactured at a reduced cost, a luminance scattering is relatively large in a low gray level region. Therefore, a charge amount of the charge-coupled device varies with respect to the same exposure-time. For example, when the charge amount of the charge-coupled device is insufficient, a display defect such as a mura may occur, and when the charge amount of the charge-coupled device is excessive, a saturation defect occurs.

SUMMARY

Aspects of embodiments of the inventive concept are directed toward a vision inspection apparatus (e.g., a vision defect or bending defect inspection apparatus) for obtaining an adaptive inspection signal according to a display panel.

Aspects of embodiments of the inventive concept are directed toward a method of driving the vision inspection apparatus.

According to an embodiment of the inventive concept, there is provided a vision inspection apparatus including an inspection controller which displays a grid pattern with a plurality of gray levels on a display panel, an imaging converter which drives a charge-coupled device with a predetermined or set exposure-time and converts the grid pattern displayed on the display panel into a grid pattern signal, a charge calculator which calculates a charge amount per unit time for each color of a reference gray level using a reference gray level signal, included in the grid pattern signal, and the set exposure-time and an exposure-time calculator which calculates an optimum exposure-time for each color of the reference gray level based on a target charge amount of the reference gray level.

In an embodiment, the plurality of gray levels may include a low-gray level and a full-gray level.

In an embodiment, when the reference gray level is displayed on the display panel, the charge-coupled device may be configured to be driven based on the optimum exposure-time for each color of the reference gray level that is less than a threshold exposure-time.

In an embodiment, when the reference gray level is displayed on the display panel, the charge-coupled device may be configured to be driven based on a green optimum exposure-time of the reference gray level that is less than a threshold exposure-time.

In an embodiment, the inspection controller may be configured to determine a display area of the display panel using the grid pattern.

In an embodiment, the vision inspection apparatus may further include a tri-stimulus value calculator which calculates color tri-stimulus values of the full-gray level using a full-gray level color signal, included in the grid pattern signal, and calculates tri-stimulus values of the reference gray level using a reference gray level signal included in the grid pattern signal, and a color-luminance value calculator which calculates a luminance value for each color of the reference gray level using color tri-stimulus values of the full-gray level and tri-stimulus values of the reference gray level.

In an embodiment, the charge calculator may be configured to calculate a charge amount per unit time for each color of the reference gray level using the luminance value for each color of the reference gray level and the set exposure-time.

In an embodiment, the vision inspection apparatus may further include an inspection corrector which calculates a correction value for correcting a vision defect of the display panel using the reference gray level signal based on the optimum exposure-time for each color of the reference gray level.

In an embodiment, the inspection corrector may be configured to calculate a mura correction value for correcting a mura of the display panel.

In an embodiment, the inspection corrector may be configured to calculate a color correction value for image quality correction of the display panel.

According to an embodiment of the inventive concept, there is provided a method of driving a vision inspection apparatus, the method including displaying a grid pattern with a plurality of gray levels on a display panel, driving a charge-coupled device with a predetermined or set exposure-time, converting the grid pattern displayed on the display panel into a grid pattern signal, calculating a charge amount per unit time for each color of a reference gray level using a reference gray level signal, included in the grid pattern signal, and the set exposure-time and calculating an optimum exposure-time for each color of the reference gray level based on a target charge amount of the reference gray level.

In an embodiment, the plurality of gray levels may include a low-gray level and a full-gray level.

In an embodiment, the method may further include driving the charge-coupled device based on the optimum exposure-time for each color of the reference gray level that is less than a threshold exposure-time, when the reference gray level is displayed on the display panel.

In an embodiment, the method may further include driving the charge-coupled device based on a green optimum exposure-time of the reference gray level that is less than a threshold exposure-time, when the reference gray level is displayed on the display panel.

In an embodiment, the method may further include determining a display area of the display panel using the grid pattern.

In an embodiment, the method may further include calculating color tri-stimulus values of the full-gray level using a full-gray level color signal, included in the grid pattern signal, and calculating tri-stimulus values of a reference gray level using a reference gray level signal, included in the grid pattern signal, and calculating a luminance value for each color of the reference gray level using color tri-stimulus values of the full-gray level and tri-stimulus values of the reference gray level.

In an embodiment, the method may further include calculating a charge amount per unit time for each color of the reference gray level using the luminance value for each color of the reference gray level and the set exposure-time.

In an embodiment, the method may further include calculating a correction value for correcting a vision defect of the display panel using the reference gray level signal based on the optimum exposure-time for each color of the reference gray level.

In an embodiment, the method may further include calculating a mura correction value for correcting a mura of the display panel.

In an embodiment, the method may further include calculating a color correction value for correcting an image quality of the display panel.

According to the embodiments, the vision inspection apparatus calculates an optimum exposure-time for obtaining a maximum charge amount for each gray level for the display panel. Therefore, the vision inspection apparatus may obtain an accurate reference gray level signal for the reference gray level displayed on the display panel. Accordingly, inspection correction values of the display panel may be accurately calculated.

In addition, the vision inspection apparatus may obtain the optimum exposure-time of the charge-coupled device adaptively to the optical characteristics of the display panel irrespective of the luminance dispersion or the transmittance characteristics of the display panel. The vision inspection apparatus may prevent or protect from a saturation defect due to an increase of the exposure-time and a decrease of the correction accuracy due to a lack of the exposure-time.

