The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 24, 1985
Filed:
Jan. 19, 1984
Richard W Midland, Inverness, IL (US);
Zenith Electronics Corporation, Glenview, IL (US);
Abstract
A dynamic focusing circuit for a CRT includes a DC coupled parabolic voltage waveform generator having a first capacitor supplied with constant charging current from a transistor for developing a sawtooth voltage waveform thereacross, a first switch transistor for discharging the first capacitor at a horizontal frequency rate, a second capacitor DC coupled to the first capacitor through a voltage-to-current generator transistor for developing a parabolic voltage waveform thereacross and a second switch transistor for discharging the second capacitor in synchronism with the first capacitor. Tilt and amplifier control transistors are DC coupled to the second capacitor. A vertical rate parabolic correction waveform is also developed by similar circuitry. The upper transistor in a cascode amplifier develops a high voltage replica of both the horizontal and vertical parabolic correction waveform voltages for application to the focus electrode of a CRT. Horizontal and a vertical amplifier transistors are coupled in parallel in the lower portion of the cascode amplifier and are supplied with the corresponding parabolic correction voltages.