Zenith Electronics Corporation

Zenith Radio Corporation

Wayne R Chiodi

Robert J Adler

Charles J Prazak

Richard M Gorski

Allen P Blacker, Jr

Norman F Gioia

Suresh R Borkar

Lionel A Watson

Bryan R Grummon

In a color CRT with an in-line gun and a pin cushion correcting yoke, there is disclosed an eyebrow effect electronoptical distortion correction device comprising two pair of coils, each pair having a coil on each outer electron beam side of the neck in the plane of the beams. The coil pairs are spaced apart along the Z-axis between the gun and the yoke and are driven by a sawtooth current having a bow-tie envelope synchronous with the raster scan to correct the dynamic, antisymmetrical eyebrow effect apparent as a purity defect on the raster.

Cathode ray tube dynamic electron-optic eyebrow effect distortion

A planar tension mask is disclosed for use in a color cathode ray tube having a substantially flat faceplate. The shadow mask according to the invention has an aperture pattern characterized by the vertical pitch of the apertures being constant, but with the horizontal pitch of the apetures increasing outwardly from the mask center according to a function which is parabolic with horizontal displacement, and parabolic with vertical displacement. The horizontal pitch increase is isotropic in the sense that the increase in pitch is the sum of the horizontal displacement increase and the vertical displacement increase. A color cathode ray tube front assembly having such a shadow mask is also disclosed.

Flat tension mask color CRT front assembly with improved mask for

An electron gun system providing beam convergence is disclosed for use in a color CRT display system. Means including cathode means develop three electron beams, two of which are off-axis with respect to a center axis of the gun. A plurality of electrodes means provide shaping and focusing, and assisting in the converging of the beams at the tube screen. Means are provided for developing and applying to the electrode means a pattern of potentials which form field components in the gaps therebetween; at least one of the electrode means receives a varying dynamic focusing voltage for dynamically focusing the beams as they are deflected across the screen. At least selected ones of the plurality of electrodes means for the off-axis beams are so structured and arranged as to cause a plurality of the field components to be asymmetric and effective to converge the off-axis beams. The strengths of the asymmetric field components vary in response to changes in the dynamic focus voltage. The asymmetric field components according to the invention have such polarity and strength, due to the structuring and arranging of the electrodes, and the application of the pattern of voltages, that a change in the levels of the dynamic focus voltage causes a change in the strength of each of the asymmetric field in a direction effective to additively deflect a common off-axis beam in a common angular direction so as to create a strong dependency of the convergence of the off-axis beams on variations in the focus voltage.

Electron gun system with dynamic focus and dynamic convergence

This disclosure pertains to the production of self-converged color CRT display systems, and in particular to a method of reducing the effects of off-axis deflection defocusing of electron beams in such systems. The disclosed method comprises installing in the neck of each color CRT bulb a three beam in-line-type electron gun whose mechanical and electrical design parameters are such that the beams in their free fall state have a selected nominal value of underconvergence at the screen which is such that substantially the entire population of production tubes is underconverged. On the neck of each tube is installed a self-converging yoke which establishes, in addition to main deflection magnetic field components, an astigmatic field component which self-converges said beams, but which undesirably introduces astigmatic deflection defocusing of the beams when deflected off the tube axis. Static convergence of said beams at said screen is effected by establishing a static astigmatic quadrupolar magnetic field component common to all three beams and opposite to said astigmatic yoke field component which, while accomplishing the desired static beam convergence, deliberately introduces an astigmatic distortion of said beams. The distortion is a function, for each tube, of the free fall underconvergence value for that tube and at least partially compensating the deflected beams for the deflection defocusing of the beams by the oppositely directed astigmatic yoke field component.

Method of correcting deflection defocusing in self-converged color CRT

A deflection yoke for a television picture tube having coplanar in-line electron guns includes vertical and horizontal coil windings selected for providing self-convergence and north/south pin cushion correction. The desired characteristics are achieved by winding the vertical coil for converging the electron beams along the vertical axis of the picture tube viewing screen and by winding the horizontal coil in a saddle configuration wherein an aperture devoid of wire turns is provided in the front end of the horizontal coil facilitating the achievement of a high third harmonic content winding distribution simultaneously with a comparatively high fifth harmonic content winding distribution.

Self converging, north/south pin cushion corrected hybrid yoke

An electromagnetic deflection yoke includes saddle wound horizontal deflection coils mounted to a liner. The vertical coils are toroidally wound on a smooth, magnetically permeable core having the form of a segmented frusto-conic section and are in contact with the opposite side of the liner. Each vertical coil comprises a repeatable multilayer precision stack of wire turns with only the wire turns providing the support for maintaining the multilayer precision stack. The core has positioning notches which mate with locating tabs on the liner and provide for an accurate positioning of the vertical deflection coils with respect to the horizontal deflection coils.

Growing community of inventors

Northbrook, IL, United States of America

Wayne R Chiodi