US 4,228,433 A · Information display position-defining circuit for a cathode ray tube

Abstract

There is provided an information display position-defining circuit comprising a local pulse oscillator reset by a horizontal synchronization pulse; a horizontal pulse counter which is reset by the horizontal synchronization pulse and counts an output pulse from the local pulse oscillator; a vertical pulse counter which is reset by a vertical synchronization pulse and counts the horizontal synchronization pulse; and a character position signal generator for issuing a signal denoting a character display position in response to output signals from the horizontal and vertical pulse counters. The circuit further includes a signal generator designed to selectively send forth a first signal having the same frequency and phase as the horizontal synchronization pulse and a second signal having the same frequency as the first signal, but having a phase different from a first signal; and a comparator for comparing the phases of an output signal from the signal generator and vertical synchronization pulse and, at the same time of synchronization between both phases, selecting the first or second signal.

Claims13

Dependent claims

An information display position-defining circuit for a cathode-ray tube comprising:

a local pulse oscillator producing an output pulse train in response to a horizontal synchronization pulse;
first signal-generating means for producing a horizontal position signal corresponding to an output signal from the local pulse oscillator;
second signal-generating means for generating a first signal having a prescribed phase relationship with the horizontal synchronization pulse during a first operation mode and for generating a second signal having a different phase from the first signal during a second operation mode;
operation mode-setting means connected to receive an output signal from said second signal generating means and a vertical synchronization pulse for producing an output signal to change over the operation mode of said second signal generating means when substantial synchronization arises between the output signal from said second signal generating means and the vertical synchronization pulse;
third signal-generating means for producing a vertical position signal in response to an output signal from the second signal-generating means;
and
fourth signal-generating means for producing an information display position-specifying signal corresponding to the horizontal position signal and vertical position signal delivered from the first and third signal generators.

4 more elements

Dependencies are inferred from the claim text.

Information display position-defining circuit for a cathode ray tube

Life of this patent

Information display position-defining circuit for a cathode ray tube

Life of this patent

Abstract

Claims13