28.3: Projection CRT Electron Gun with High-Resistive-Layer Focus Lens

An electron gun for a projection CRT has been developed by using a high resistive layer formed on the inside wall of a glass tube as the main lens structure. In an effort to achieve an ultimate electron gun, (1) design technology (2) resistor material to meet the system requirement, and (3) precision machining technology, have been made. As a result, an electron gun with its main lens consisting of a high resistive film has been successfully developed. The CRT utilizing this electron gun which has the current neck diameter of 29.1 mm shows the following characteristics. 1 An electron gun achieved an effective electron lens diameter of 40 mm. 2 The beam spot diameter was reduced by 11%. 3 Magnetic permeability characteristics in high frequency range was improved 5 times.