HORIZONTAL DYNAMIC FOCUS CIRCUIT

• Main Author: SEKO KAZUYUKI
• Format: Patent
• Language: English
• Published: 05.07.1991
• Subjects: ADVERTISING; ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICESUSING STATIC MEANS TO PRESENT VARIABLE INFORMATION; CRYPTOGRAPHY; DISPLAY; EDUCATION; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; PHYSICS; PICTORIAL COMMUNICATION, e.g. TELEVISION; SEALS

PURPOSE:To maintain the specified crest value of parabolic waveforms and to prevent the deterioration of a focusing characteristic by using the secondary side inductance of a reactor transformer in L of an LC resonance circuit which generates the parabolic waves and changing the inductance according to a horizontal scanning frequency. CONSTITUTION:A horizontal synchronizing signal H.IN is inputted and is subjected to FV conversion in the IC1; thereafter a current i1 is passed to the primary side of the reactor transformer T by executing current control. The flyback pulse taken out of the secondary side of FBT is converted to the parabolic waves by the resonance circuit of L2 and C1 of the device T and is amplified in the IC2; thereafter, the waves are subjected to the cutting of a DC component by the C2 and the voltage control by the R1. The anode voltage Eb of the CRT is divided by the R2, R3 and is applied to the focus electrode of the CRT. The L on the secondary side of the reactor transformer changes according to the horizontal scanning frequency according to this constitution and, therefore, the crest value of the parabolic waveforms is always constant and the deterioration of the focusing characteristic is prevented.