Abstract A high speed electromagnetic deflected electrostatic focus cathode ray tube display having a relatively short magnetic time constant by controlling the gun structure. The volume resistivity and the thickness of resistive materials used in the neck of the cathode ray tube that are cut by changing magnetic flux fields, are selected to provide a relatively short time constant. In one arrangement, the tube focusing control elements near the deflection yoke are formed on a precision ground structure of glass or other suitable ceramic materials. In another arrangement the elements of the tube that are intercepted by the changing magnetic flux are deposited or formed on a precision ground portion of the tube neck. Material deposited on the tube structure or on the tube neck is of a selected maximum volume resistivity and a selected small thickness so that the overall operation has a relatively short time constant.
A high speed magnetic deflection cathode ray tube system having a selected magnetic deflection time constant comprising a glass envelope including a neck portion having first and second ends, a magnetic deflection yoke positioned at the second end of said neck portion and passing deflection flux through a predetermined portion of said neck portion, and an electron gun including a focus structure, means within said predetermined portion including at least a portion of said focus structure of said electron gun, said focus structure of said means within said predetermined portion including a tube of non-magnetic material having inner and outer surfaces and including a deposited film of a resistive material deposited on one or both of said surfaces, said resistive material being of a selected bulk resistivity ρ and selected thickness t so said deposited film provides a selected time constant τ of said deposited film caused by the eddy currents induced therein by the deflection flux, in accordance with the relationship ##EQU2## where μ is the permeability of the resistive material, said means providing said time constant equal to or less than 100 nanoseconds.
Claim 2
Dependent Claim
185 words
A high speed magnetic deflection cathode ray tube system having a selected magnetic deflection time constant comprising a glass envelope including a neck portion having first and second ends, a magnetic deflection yoke positioned at the second end of said neck portion and passing deflection flux through a predetermined portion of said neck portion, and an electron gun including a focus structure, means within said predetermined portion including at least a portion of said focus structure of said electron gun, said focus structure of said means within said predetermined portion including a tube of non-magnetic material having inner and outer surfaces and including a deposited film of a resistive material deposited on one or both of said surfaces, said resistive material being of a selected bulk resistivity ρ and selected thickness t so said deposited film provides a selected time constant τ of said deposited film caused by the eddy currents induced therein by the deflection flux, in accordance with the relationship ##EQU2## where μ is the permeability of the resistive material, said means providing said time constant equal to or less than 100 nanoseconds.
Claim 3
Dependent Claim
12 words
The system of claim 1 in which said resistive material includes graphite.