Applications of the Voltage Imaging<SUP>TM</SUP> technique in testing active arrays used in AMLCDs have been widely discussed. Voltage Imaging<SUP>TM</SUP> is well known for its simplicity in interfacing with active array panels, and its superior voltage measurement accuracy and repeatability. It is also known for having broad test applicability for many AMLCD panel design technologies, such as TFT, MIM, diode and panels with integrated drivers. This paper briefly discusses a recent improvement related to the application of Voltage Imaging<SUP>TM</SUP> for L-contact panel testing. As the panel manufacturers are trying to reduce the manufacturing cost, the number of panels on one substrate also increases which, in several cases, leaves only enough room to add ESD protection shorting rings on two of the four sides of a panel. Since this is the trend of the industry, a methodology that can be employed to test L-contact panels with Voltage Imaging<SUP>TM</SUP> is presented in this paper.
The spatial resolution of the Voltage Imaging<SUP>TM</SUP> technology is defined as the smallest pixel pitch that can be measured for a certain voltage accuracy. It is a function of the EO material, the image forming optics, the CCD resolution and electronic filter bandwidth, and the image processor resolution and filter bandwidth. This paper starts from a square wave input signal with 100% modulation on the LCD panel. The contrast transfer function (CTF) for each individual stage in the voltage imaging process is derived. They include the EO material, the objective lens and imaging lens, the CCD camera spatial sampling, the CCD camera electronics filtering, and the image processor sampling and filtering. Simulated data is presented.
Photon Dynamics' IPT system provides high throughput and excellent voltage measurement sensitivity on an AMLCD panel. It is based upon an electro-optical technology to measure the voltage stores on an LCD pixel of an AMLCD active plate. This paper discusses the system performance requirements. From these we derive the optical subsystem requirements. The optical design form and its performance are presented. The current system status, system design issues, and the future improvements also are discussed.