Abstract A synchronizing signal producing system for a television device comprises a first counter for receiving input clock pulses having a frequency of an integral multiple of a horizontal synchronizing signal to generate output pulses having a vertical synchronizing frequency with a larger width than that of the clock pulse; a second counter for counting the clock pulses in synchronization with the arrival of a vertical synchronizing signal from the outside; a comparison pulse generator coupled with the second counter so as to derive a clock pulse counted, by the second counter, at a time corresponding to substantially the center of the width of the output pulse from the first counter; a phase comparator for comparing the phase of the output pulse from the comparison pulse generator with that of the output pulse from the first counter; and an output switching circuit for deriving as a vertical synchronizing output for the television device the output pulse of the first counter when the output pulse from the first counter and that from the comparison pulse generator are evaluated by the comparator to be in phase and the output pulse associated synchronously with the vertical synchronizing signal obtained from the outside through the second counter when they are evaluated by the comparator to be out of phase, whereby the television device can be driven always in substantially synchronized condition not only in a case where the vertical synchronizing signal from the outside is equal in frequency to a standard vertical synchronizing signal, but also in a case where the received vertical synchronizing signal is somewhat different in frequency from the standard vertical synchronizing signal.
Inventors
👤 N Kokado
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-29 05:16
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/04; H04N5/12
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
209 words
A synchronizing signal producing system for a television device comprising a first counter for receiving clock pulses having a frequency of an integral multiple of a horizontal synchronizing signal to generate an output pulse having a vertical synchronizing frequency with a larger width than that of the clock pulses; a second counter for counting the clock pulses in synchronization with the arrival of a vertical synchronizing signal from an outside; a comparison pulse generator coupled with said second counter to generate the clock pulse counted, by said second counter, at a time corresponding to substantially the center of the width of the output pulse from said first counter; a phase comparator for comparing the phase of the output pulse from said comparison pulse generator with that of the output pulse from said first counter; and an output switching means for producing as a vertical synchronizing output for the television device the output pulse of said first counter when the output pulse from said first counter and that from said comparison pulse generator are evaluated by said phase comparator to be in phase and the output pulse associated synchronously with the vertical synchronizing signal from the outside when they are evaluated by said phase comparator to be out of phase.
Claim 2
Dependent Claim
209 words
A synchronizing signal producing system for a television device comprising a first counter for receiving clock pulses having a frequency of an integral multiple of a horizontal synchronizing signal to generate an output pulse having a vertical synchronizing frequency with a larger width than that of the clock pulses; a second counter for counting the clock pulses in synchronization with the arrival of a vertical synchronizing signal from an outside; a comparison pulse generator coupled with said second counter to generate the clock pulse counted, by said second counter, at a time corresponding to substantially the center of the width of the output pulse from said first counter; a phase comparator for comparing the phase of the output pulse from said comparison pulse generator with that of the output pulse from said first counter; and an output switching means for producing as a vertical synchronizing output for the television device the output pulse of said first counter when the output pulse from said first counter and that from said comparison pulse generator are evaluated by said phase comparator to be in phase and the output pulse associated synchronously with the vertical synchronizing signal from the outside when they are evaluated by said phase comparator to be out of phase.
Claim 3
Dependent Claim
75 words
A synchronizing signal producing system as claimed in claim 1 wherein there is further provided a third counter capable of counting any number of output pulses from said first counter and being brought to a reset position by that signal from said phase comparator which represents the out-of-phase, and said output switching means is designed to deliver the output pulse from said first counter only when an output signal is derived from said third counter.
Claim 4
Dependent Claim
106 words
A synchronizing signal producing system as claimed in claim 2 wherein there is further provided another phase comparator for comparing the phase of the output pulse from said comparison pulse generator with the phase of a pulse having a smaller width than that of the output pulse from said first counter and synchronized therewith, and said output switching means is designed to deliver the output pulse from said first counter only when said another phase comarator detects an output signal indicating that both input pulses are in phase, said second-mentioned pulse having a larger width than that of the output pulse from said comparison pulse generator.
Claim 5
Dependent Claim
51 words
A synchronizing signal producing system as claimed in claim 1 further comprising a noise canceller for generating a signal indicating no output pulse period of said first counter and interruPting the supply of those noise signals applied to the system from the outside which are generated between actual vertical synchronizing signals.
Claim 6
Dependent Claim
65 words
A synchronizing signal producing system as claimed in claim 4 further comprising a circuit for delivering from said output switching means the output pulse from said first counter whenever no vertical synchronizing signal is supplied from the outside to the system, said circuit being rendered operative by an output signal from said noise canceller and inoperative by the output pulse from said comparison pulse generator.