• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.147-150
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• 2002

A light guide panel is an element of the LCD backlight module that is often used for the display of compact electronic devices. In this study, a laser marking system is proposed to fabricate light guide panel, which can be replaced of other manufacturing methods such as silk printing, stamping, and v-cutting methods. The objectives of this research are the establishment of laser marking system, evaluation of laser marking parameters, understanding marking process, application to PMMA, reliability test and quality inspection. A 50W $CO_2$ laser (CW) was used to perform different experiments in which, the influence of some processing parameters (average power, scanning speed) on the geometry and quality of groove pattern was studied. The width of the etched grooves increases with increasing a laser power and decreasing a scan speed. In order to analyze surface characteristics and optical properties (luminance, uniformity), SEM photography and BM7 (luminance measuring system) were used. As a result, the optimal conditions of the process parameters were determined.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.1
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• pp.107-117
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• 2016

STD method using a mean and standard deviation is widely used in various inspection systems. The result of detection using the STD method is very dependent on the threshold value. This paper proposes an adaptive defect detection algorithm to with a precise detection of an ultimate defect. The proposed method is determined threshold value adaptively using a skewness that indicates a similarity of intensity and normal distribution of image. In the experiment, we used a various TFT-LCD images for a quantitative evaluation of defect detection performance evaluation result to prove the performance of the proposed algorithm.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1079-1080
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• 2008

To improve productivity of TFT-LCD and PDP, it is required that the inspection system of flat glass should be established. It is composed of robot arms, base table, and laser sensors. This paper focuses on three non-contact laser sensors. After testing three laser sensors, LG-G30 is selected.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1353-1356
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• 2004

In recent year, OLED(organic light emitted display) is used as the next generation device of FPD. OLED have been replacing the flat panel display device such as LCD, STN-LCD and TFT because this device is more efficient, economic and simple than those FPD devices, and this need not backlight system for visualization. The performance and efficiency of OLED is related with surface defect of ITO coated glass substrate. The typical surface defect of glass substrate is nonuniformity and bad surface roughness. ITO coated glass substrate is destroied for inspection about surface roughness and non-uniformity. Generally detection of the defects in the surface for ITO coated glass substrate is dependent on operator's experience. In this research, relationship between working parameter and surface non-uniformity is studied using regression analysis.

• Journal of Information Display
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• v.10 no.4
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• pp.202-205
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• 2009

An automated circuit repair system was developed for enhancing the yield of nondefective liquid crystal panels, focusing on the resist patterns on the circuit material layer of thin-film transistor (TFT) substrates prior to etching. The developed system has an advantage over the parallel conventional system: In the former, the repair conditions depend on the type of resist whereas in the latter, the repair parameters must be fine-tuned for each circuit material. The developed system consists of a resist pattern defect inspection system and a pattern repair system for short and open defects. The repair system performs fine corrections of abnormal areas of the resist pattern. The open-repair system is equipped with a syringe to dispense resist. To maintain a stable resist diameter, a thermal insulator was installed in the syringe system. As a result, the diameter of the dispensed resist became much more stable than when no thermal insulator was used. The resist diameter was kept within the target of $400{\pm}100{\mu}m$. Furthermore, a prototype system was constructed, and using a dummy pattern, it was confirmed that the system worked automatically and correctly.

• Journal of the Semiconductor & Display Technology
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• v.3 no.4
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• pp.51-55
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• 2004

In the design stage of high precision manufacturing/inspection FAB facilities, it is necessary to investigate the allowable vibration limits of high precision equipments and to study structural dynamic characteristics of C/R and Sub-structure in order to provide structural vibration criteria to satisfy these allowable limits. The goal of this study is to investigate the dynamic characteristics of PC-Type mock-up structures designed for next generation TFT-LCD FAB through experiments and analysis procedures. Therefore, in order to provide a proper dynamic structural design for high precision manufacturing/inspection work process, these allowable limits must be satisfied.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.6
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• pp.743-748
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• 2009

In this paper, we propose an effective method to extract background components in automated vision inspection system for polarized film used in TFT LCD display panels. The test image signals are typically composed of three components such as ununiform background, random noises and target defect signals. It is important to analyze the background signal for accurate extraction of defect components. Two dimensional continuous wavelets with first derivative gaussian is used. This methods can be applied for reliable extraction of defect signal by elimination of the background signal from the original image. The proposed method outperforms over conventional FFT methods.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2005.09a
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• pp.49-54
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• 2005

In the case of a sensitive equipment, it require a vibration free environment to provide its proper function. Especially, lithography and inspection device, which have sub-nanometer class high accuracy and resolution, have come to necessity for producing more improved Giga Class semi conductor wafers. The aim of this study is to evaluate the allowable vibration response of a precision inspect ion equipment, which has some trouble in field, by using experimental measurement data and to proposal a proper ant i-vibration method.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.8
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• pp.761-771
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• 2009

Detecting defects on FPD (Flat Panel Display) color filter before the full panel is made is important to reduce the manufacturing cost. Among many types of defects, the low contrast blemish such as Suzi Mura is difficult to detect using standard CCD cameras. Even skilled inspectors in the inspection line can hardly identify such defects using bare eyes. To overcome this difficulty, point spectrometer has been used to analyze the spectrum to differentiate such defects from normal color filters. However, scanning ever increasing-size color filters by a point spectrometer takes too long time to be used in real production line. We propose a system using a spectral camera which can be viewed as a line scan camera composed of an array of point spectrometers. Three types of lighting system that exhibit different illumination spectrums are devised together with a calibration method of the proposed spectral camera system. To visualize the defect areas, various processing algorithms to identify and to enhance the small differences in spectrum between defective and normal areas are developed. Experiments shows 85% successful visualization. of real samples using the proposed system.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.7
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• pp.675-682
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• 2009

Instead of direct driving like BLDC, the induction principle is adopted as a driving one for planar stage. The stage composed of four linear induction motors put in square type is activated by two-axial forces; low-frequency attractive force and thrust force of the linear induction motors. Here, the modified vector control whose new inputs are q-axis current and dc current biased to three phase current instead of d-axis current or flux current is applied extensively to overall motion of the stage. For the developed system, the precision step test and the constant velocity test are tried to guarantee its feasibility for TFT-LCD pattern inspection. However, to exclude a discontinuity due to phase shift and minimize a force ripple synchronized with the command frequency, the initial system is revised to the antagonistic structure over the full degree of freedom. Concretely describing, the porous air bearings guide an air-gapping of the stage up and down and a pair of liner induction motors instead of single motor are activated in the opposite direction each other. The performances of the above systems are compared from trapezoid tracking test and sinusoidal test.