Abstract: In an electron gun for a color cathode ray tube including a cathode structure having three electrodes, a control electrode and a screen electrode, and a plurality of focus electrodes and last accelerating electrodes for forming electron lenses, the cathode structure includes a rimmed electrode member, an insulating member inserted into the electrode member and having an indentation formed on the upper surface thereof, a field emission array cell having a base member which is inserted into the indentation, and a plurality of supporting members installed at the insulating member for pressing down on the upper surface of the edge of the field emission array cell which is inserted into the indentation toward the upper surface of the insulating member. Thus, the strength of attachment between the insulating member and a field emission device is improved.

Abstract: A directly heated cathode structure includes a porous pellet impregnated with a thermionic emission material, a supporter for applying electrical power, and a filament fixed to the porous pellet, having an end, and fixed to the supporter, wherein the filament includes a connecting portion wider than the filament and fixed to the supporter at the end of the filament. The cathode structure is suitable for a color CRT such as a color television or a CRT for industrial use and having a large screen.

Abstract: A directly heated cathode structure includes at least one porous pellet containing electron emission material and filaments secured to at least three side surfaces of the porous pellet to support the pellet stably and prevent vibration caused by shock and potential deformation. Each filament is supported by an insulating block and more than one pellet may be mounted on a single insulating block. As a result, a highly reliable cathode ray tube can be manufactured.

Abstract: A device for driving a directly heated cathode of a cathode ray tube eliminating a delay due to inductance of a transformer. A transformer that produces the heater-heating signal voltage applied to the cathode includes a secondary coil divided into first and second coils. The voltage induced in the first coil is used for the heater-heating voltage and the signal induced in the second coil is synchronized with the voltage induced in the first coil and used as a bias voltage for turning on and off a switching element in synchronization with the heater-heating voltage. The switching element turns on only when the heater-heating signal voltage is applied to a control terminal of the switching element.

Abstract: An electron gun for cathode ray tubes which is easily assembled and reduces the cost is disclosed. The electron gun has a cathode holding structure. The cathode holding structure includes a support bracket which is fixedly fitted in the first electrode. The support bracket is provided with a plurality of insert holes spaced apart from each other. A plurality of hollow cases are received in the insert holes of the support bracket respectively and fixed to the support bracket. A cathode is concentrically received in each hollow case. The cathode holding structure also has an insulating material which is filled in the hollow case in order to hold and insulate the cathode in the hollow case. In the present invention, the gap between the cathodes and first electrode of the electron gun is easily adjusted thereby preventing the inferiority of the electron gun.

Abstract: A directly heated cathode structure includes a porous pellet impregnated with an electron radiating material, a cup-shaped container holding the porous pellet, a metal member welded to the container, and a filament between the container and the metal member, restricting thermionic emission through the base and sides of the pellet and extending the life of the cathode structure.

Abstract: A directly heated cathode structure includes a porous pellet impregnated with a cathode material, a first metal member fixed to a surface of the porous pellet, a second metal member welded to the first metal member, and a filament interposed between the first and second metal members. A method for manufacturing a directly heated cathode structure includes manufacturing a porous pellet having a multiplicity of cavities, welding a first metal member to a surface of the porous pellet with a brazing layer, impregnating the cavities of the pellet with an electron radiating material, and welding a second metal member to the first metal member with a filament disposed between the first and second metal members. The useful life of the cathode structure is prolonged since thermions are not emitted through the surface of the pellet covered by the metal member.

Abstract: A directly heated cathode structure includes a porous pellet impregnated with a cathode material, filaments connected to the porous pellet, a support supporting the filament, and an insulation block supporting the support, wherein the filaments are supported on the porous pellet by at least one auxiliary member. The supporting structure is very strong and the quality and productivity can be greatly improved by improvement of the filament welding process using the auxiliary members.