Analysis of Aperture Alignment Tolerance for Clear Gun

Analysis of Aperture Alignment Tolerance for CLEAR Gun

Hsiang Lin Chang, Chun Hsien Yeh R&D Division, Chunghwa Picture Tubes 80 Hsing-Shan Rd., Yangmei, Taoyuan, Taiwan 32606, R.O.C. e-mail address: yehch@mail.cptt.com.tw, changhl@mail.cptt.com.tw

ABSTRACT The misalignment sensitivity of the individual gun part of our CLEAR Gun (QPF gun structure) on the effect of focus performance of CRT is clearly elucidated in this paper by using the computer simulation. Modeling data show that the focus deterioration or halo is mainly resulted from the G2 part misalignment. Experimental results agree well with the modeling data. INTRODUCTION In the high-resolution color display tube (CDT) the assembly-precision of the electron gun grids becomes more important to maintain the higher focus performance. The misalignment of gun grids will deteriorate the focus performance resulted from the halo phenomenon. In general the aperture alignment test (so-called APL test) are used to judge the electron gun assembly-precision while the tube was made. In QPF Gun structure even if the APL test results is not good enough, we still don’t know which grid of the electron gun misaligned because of there is a pre-focus lens between the beam forming region (BFR) and main-lens region (ML). In our CLEAR (Chain-Link Enhanced Aperture Rim) [1] gun we compute the APL sensitivity and the focus voltage changes and halo phenomenon of each grid’s misalignment by

using computer modeling (EBS program) and establish the APL sensitivity table. By using this APL sensitivity table we could shorten the analysis time of misalignment and resolve the production problems.

SIMULATION RESULTS The QPF gun’s misalignment of gun grids includes rotation, shift and tilt. The effects of gun grid’s rotation have been discussed by computer modeling [2]. In this paper we will explore the effects of gun grid’s shift further. 1. Halo phenomenon and APL test In general, most of the focus failure of QPF Gun resulted from...