High-brightness and high-resolution projection CRT

A new 3-in. projection CRT that YAG(Y3Al5O12) single crystal is used for the substrate of the phosphor screen has been developed. This phosphor screen has a number of unusual properties. The substrate has a very high coefficient of thermal conductivity and a high transparency. To obtain matched sealing, a low melting point solder has been developed to combine the substrate with the glass envelope. An electrostatic-electromagnetic focusing electron gun with large emitting current and high-resolution is developed. As a result, beam spot diameters of 0.065 mm and 0.080 mm are achieved at cathode currents of 0.5 and 1 mA, respectively. The focusing luminance is 1.4 X 105 cd/m2 for green phosphor-screen at cathode current of 1 mA and the anode voltage of 29 KV. The focusing luminances of red phosphor-screen and blue phosphor screen are 6.4 X 104 cd/m2 and 8 X 103 cd/m2 at cathode current of 1 mA, respectively. Thus, the projection TV set using these projection tubes has achieved high-brightness, high-resolution and high-contrast image display.