Browse Prior Art Database

CRT Peak Current Reduction

IP.com Disclosure Number: IPCOM000048257D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Newman, EL: AUTHOR

Abstract

Peak power consumption of a directed-beam cathode ray tube (CRT) deflection circuit is reduced by rotating the deflection yoke axis by 45 degree from its usual position and rotating the displayed image through 45 degrees by means of microcode.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 72% of the total text.

Page 1 of 2

CRT Peak Current Reduction

Peak power consumption of a directed-beam cathode ray tube (CRT) deflection circuit is reduced by rotating the deflection yoke axis by 45 degree from its usual position and rotating the displayed image through 45 degrees by means of microcode.

The yoke of a CRT is used to deflect a beam of electrons to control the beam spot position on the face-plate of the tube. The yoke is an assembly of two orthogonally wound coils, one which deflects the beam in the horizontal or X- direction and the other in the vertical or Y direction. The actual deflection of the beam results from the vector addition of the independent currents in the X and Y coils.

In a vector graphics display head, these two coils are designed to have similar electrical properties, and the deflection amplifiers are usually identical. In such a system when a picture is constructed predominantly in one corner of the screen, both X and Y deflection amplifiers are working near their design limits. Fig. 1 shows contours needs a maximum current of 6 amps in both X and Y directions. The display electronics must be capable of maintaining the maximum corner current indefinitely to cater for unusual circumstances. In a typical display, 12 amps of deflection current can easily account for over 50 percent of total display power, so reducing this peak current is of paramount importance.

This peak power can be reduced by square root of 2 simply by rotating the deflection coils by 45 degrees...