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US 5,293,223 AGranted
Time-dividing method and circuit, and television white balance control utilizing such circuit
AssigneesHitachi, Ltd., Hitachi Video and Information Systems, Inc.
InventorsKoji Kawamoto, Masanori Kamiya, Hideaki Ohki, Shun Terada
Life of this patent
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Abstract
A time-dividing circuit including a first capacitor, a second capacitor, a current source for charging the first capacitor, circuitry for distributing the charge of the first capacitor to the second capacitor in a predetermined ratio, a compare for comparing the voltages on the first and second capacitors and producing a comparison output signal, circuitry for discharging the charges on the first and second capacitors, and a control circuit for producing control signals for controlling the time-dividing circuit. The time-dividing circuit can be utilized in an automatic white balance control circuit for a color television receiver.
Claims13
A time-dividing method utilizing circuitry including first and second capacitors, said method comprising the steps of:
- receiving a periodic input signal;
- discharging said second capacitor in synchronism with the period of the input signal;
- distributing a part of the charge on said first capacitor onto said second capacitor;
- discharging the charge remaining on said first capacitor after said distribution;
- re-charging said first capacitor;
- comparing the voltages on said first and second capacitors;
- and
- generating a time-dividing output signal when the voltage on said first capacitor exceeds the voltage on said second capacitor.
5 more elements
A time-dividing circuit comprising;
- a first capacitor;
- a second capacitor;
- means for charging said first capacitor;
- means for distributing the charge on said first capacitor onto said second capacitor with a predetermined ratio;
- comparing means for comparing the voltages on said first and second capacitors;
- means for discharging the charges on said first and second capacitors;
- means for preventing the overlap of any of (i) a period during which the charge on said second capacitor is discharged, (ii) a period during which the charge on said first capacitor is distributed onto said second capacitor, (iii) a period during which the charge remaining on said first capacitor is discharged, and (iv) a period during which another charge is accumulated on said first capacitor;
- and
- control means for producing control signals for controlling said respective means.
6 more elements
A time-dividing circuit for dividing the period of an input signal comprising:
- a first power supply terminal;
- a second power supply terminal;
- an output terminal;
- a first switch;
- a first capacitor having one end connected through said first switch to said first power supply terminal and the other end connected to said second power supply terminal;
- a second switch connected between said one end of said first capacitor and said second power supply terminal;
- a third switch;
- a second capacitor having one end connected through said third switch to said one end of said first capacitor and the other end connected to said second power supply terminal;
- a fourth switch connected between said one end of said second capacitor and said second power supply terminal;
- a comparator for comparing the voltages on said first and second capacitors;
- means for turning on said fourth switch at a first time point for a first time interval long enough to discharge the charge on said second capacitor;
- means for turning on said third switch at a second time point not earlier than the end of said first time interval and for a second time interval long enough to transfer charge from said first capacitor onto said second capacitor;
- means for turning on said second switch at a third time point not earlier than the end of said second time interval and for a third time interval long enough to discharge charge remaining on said first capacitor;
- and
- means for turning on said first switch during a time interval in which said second switch is turned off.
12 more elements
An automatic white balance control circuit for a color television receiver comprising:
- means for detecting cathode currents of a color television cathode ray tube;
- reference signal generating means for generating reference signals;
- comparing means for comparing the outputs of said cathode current detecting means and the reference signals from said reference signal generating means;
- control means for controlling said cathode currents;
- a first capacitor;
- a second capacitor;
- means for charging said first capacitor;
- means for distributing the charge on said first capacitor onto said second capacitor with a predetermined ratio;
- comparing means for comparing the voltages on said first and second capacitors;
- means for discharging the charges on said first and second capacitors;
- and
- control means for producing control signals for controlling said respective means.
9 more elements
An automatic white balance control circuit for a color television receiver, comprising:
- means for detecting cathode currents of a color television cathode ray tube;
- reference signal generating means for generating reference signals;
- comparing means for comparing the outputs of said cathode current detecting means and the reference signals from said reference signal generating means;
- control means for controlling said cathode currents;
- a first power supply terminal;
- a second power supply terminal;
- an output terminal;
- a first switch;
- a first capacitor having one end connected through said first switch to said first power supply terminal and the other end connected to said second power supply terminal;
- a second switch connected between said one end of said first capacitor and said second power supply terminal;
- a third switch;
- a second capacitor having one end connected through said third switch to said one end of said first capacitor and the other end connected to said second power supply terminal;
- a fourth switch connected between said one end of said second capacitor and said second power supply terminal;
- a comparator for comparing the voltages on said first and second capacitors;
- means for turning on said fourth switch at a first time point for a first time interval long enough to discharge the charge on said second capacitor;
- means for turning on said third switch at a second time point not earlier than the end of said first time interval and for a second time interval long enough to transfer charge from said first capacitor onto said second capacitor;
- means for turning on said second switch at a third time point not earlier than the end of said second time interval and for a third time interval long enough to discharge charge remaining on said first capacitor;
- and
- means for turning on said first switch during a time interval in which said second switch is turned off.
16 more elements
Dependencies are inferred from the claim text.