Broad operational range, automatic device for the change of frequency in the horizontal deflection of multi-synchronization monitors

Abstract

A broad operational range, automatic device for the change of frequency in the horizontal deflection of multi-synchronization monitors comprises an integrated circuit incorporating, a frequency meter being input and analog synchronization signal. a phase comparator having two inputs and in turn receiving said synchronization signal on one input, a voltage-controlled oscillator adapted to output a signal whose frequency is depending on said voltage and operatively linked to an output of said phase comparator, and a counter connected with its input, on the one side, to the oscillator output, and on the other side, to the meter output, said counter having an output connected to the other input of the phase comparator also forming the integrated circuit output.

We claim: 
     
       1. A broad operational range, automatic device for the change of frequency in the horizontal deflection of multi-synchronization monitors, characterized in that it comprises an integrated circuit incorporating, a frequency meter receiving an analog synchronization signal on one input;   a phase comparator having two inputs and in turn receiving said synchronization signal on one input;   a voltage-controlled oscillator adapted to output a signal having its frequency depending on said voltage and being linked operatively to an output of said phase comparator;   a counter connected with its input to the oscillator output, on the one side, and on the other side to the meter output, said counter having an output connected to the other input of the phase comparator and forming the integrated circuit output as well.   
     
     
       2. A device according to claim 1, characterized in that, within said circuit, the meter has a plurality of n outputs, each connected to a corresponding input of a storage block adapted to store the binary coding of the frequency value of the synchronization signal. 
     
     
       3. A device according to claim 2, characterized in that said storage block has n outputs connected to corresponding inputs of said counter. 
     
     
       4. A device according to claim 1, characterized in that, connected between the output of the phase comparator and the input of the voltage-controlled oscillator, is a filter for reducing the oscillation of the voltage signal output by the comparator. 
     
     
       5. A device according to claim 1, characterized in that said counter is adapted to effect a division of the output signal from the oscillator by the value N of the binary coding of said frequency of the synchronization signal. .Iadd. 
     
     
       6.  A device for tracking the frequency of an input signal, comprising: a frequency meter, connected to receive an input signal and produce a digital output corresponding thereto;   a controllable oscillator configured to synthesize a periodic signal at a frequency which is dependent on a control signal applied thereto;   a programmable dividing circuit, operatively connected to receive said digital output of said frequency meter, and said synthesized periodic signal, and to divide down said synthesized periodic signal by a factor determined by said digital output, and to provide an output accordingly;   a phase comparator configured to receive, and to detect the phase relationship between, said output of said dividing circuit and said input signal, and accordingly to produce said control signal;   whereby, when the frequency of said input signal changes, the value of said digital output changes, and therefore said dividing circuit provides inputs of random phase to said phase comparator, so that the frequency of said periodic signal varies in an unstable fashion until said oscillator returns to a locked relation with said input signal; whereby a return to synchronization is achieved more rapidly when said input signal shifts between frequencies. .Iaddend..Iadd.7. The device of claim 6, wherein the output of said dividing circuit is connected to provide an external output. .Iaddend..Iadd.8. The device of claim 6, wherein said dividing circuit comprises a counter. .Iaddend..Iadd.9. The device of claim 6, wherein said frequency meter performs a direct frequency measurement. .Iaddend..Iadd.10. The device of claim 6, wherein said controllable   
     
     
        oscillator is a voltage-controlled oscillator. .Iaddend..Iadd.11.  A circuit comprising; a phase-locked loop, operatively connected to receive an input signal and to provide a stabilized output signal accordingly;   a measurement stage, operatively connected to receive said input signal, and configured to provide a corresponding measurement value; and   a divider interposed in said phase-locked loop, and operatively connected to be controlled by said measurement value. .Iaddend..Iadd.12. The circuit of claim 11, wherein said divider comprises a counter. .Iaddend..Iadd.13. The circuit of claim 11, wherein said measurement stage performs a direct frequency measurement. .Iaddend..Iadd.14. The circuit of claim 11, wherein said phase-locked loop comprises a voltage-controlled oscillator. .Iaddend..Iadd.15. The circuit of claim 11, wherein said phase-locked loop comprises a voltage-controlled oscillator and a phase comparator, and said divider is connected between an output of said voltage-controlled   
     
     
        oscillator and an input of said phase comparator. .Iaddend..Iadd.16.  A method for tracking the horizontal frequency of a video signal, comprising the steps of: monitoring, and repeatedly deriving a digital value corresponding to, the frequency of an input signal;   synthesizing a periodic signal in a controllable oscillator in accordance with a control signal applied thereto;   dividing said periodic signal by said digital value, to produce a divided-down synthetic signal; and   detecting phase differences between said divided-down synthetic signal and said input signal, to produce a control signal which is operatively connected to control the frequency of said periodic signal generated by said controllable oscillator;   whereby, when the frequency of said input signal changes, said digital value changes, and therefore said dividing step provides inputs of random phase to said step of detecting phase error, so that the frequency of said periodic signal varies in an unstable fashion until said synthesizing step returns to phase lock with said input signal. .Iaddend..Iadd.17. The method of claim 16, wherein said divided-down synthetic signal is connected to provide an external output. .Iaddend.