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US 5,212,552 AGranted
Horizontal deflection circuit
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorYoshiaki Matsumoto
Life of this patent
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Abstract
A variable horizontal oscillator oscillates at a frequency dependent on a first control voltage. A horizontal output circuit generates a horizontal deflection current which is synchronous with an oscillation output signal from the variable horizontal oscillator. The horizontal sync frequency of an input video signal is detected. Second and third control voltages are generated which depend on the detected horizontal sync frequency. A dependence of the second control voltage upon the detected horizontal sync frequency differs from a dependence of the third control voltage upon the detected horizontal sync frequency. A power supply voltage to the horizontal output circuit is varied in accordance with the second control voltage. The third control voltage is applied to the variable horizontal oscillator as the first control voltage.
Claims5
In a display apparatus for visualizing an input video signal having a changeable horizontal sync frequency, a horizontal deflection circuit comprising:
- a variable horizontal oscillator oscillating at a frequency dependent on a first control voltage;
- a horizontal output circuit generating a horizontal deflection current which is synchronous with an oscillation output signal from the variable horizontal oscillator;
- means for detecting the horizontal sync frequency of the video signal;
- control-signal generating means for generating second and third control voltages which depend on the detected horizontal sync frequency, wherein a dependence of the second control voltage upon the detected horizontal sync frequency differs from a dependence of the third control voltage upon the detected horizontal sync frequency;
- means for varying a power supply voltage to the horizontal output circuit in accordance with the second control voltage;
- and
- means for applying the third control voltage to the variable horizontal oscillator as the first control voltage,
- wherein the control-signal generating means comprises:
- first memory means for memorizing predetermined different representative horizontal frequencies;
- second memory means for memorizing predetermined representative values of the second control voltage which correspond to the representative horizontal frequencies respectively;
- third memory means for memorizing predetermined representative values of the third control voltage which correspond to the representative horizontal frequencies respectively;
- means for selecting two adjacent members of the representative frequencies, wherein the detected horizontal sync frequency is present between the selected two adjacent representative frequencies;
- means, operating on the second memory means, for reading out representative values of the second control voltage which correspond to the selected two adjacent representative frequencies respectively;
- means, operating on the third memory means, for reading out representative values of the third control voltage which correspond to the selected two adjacent representative frequencies;
- first calculating means for calculating a desired value of the second control voltage from the detected horizontal sync frequency, the selected two adjacent representative frequencies, and the readout representative values of the second control voltage;
- means for generating the second control voltage which actually has a level equal to the calculated desired value of the second control voltage;
- second calculating means for calculating a desired value of the third control voltage from the detected horizontal sync frequency, the selected two adjacent representative frequencies, and the readout representative values of the third control voltage;
- and
- means for generating the third control voltage which actually has a level equal to the calculated desired value of the third control voltage.
16 more elements
In a display apparatus for visualizing an input video signal having a changeable horizontal sync frequency, an improved horizontal deflection circuit, wherein the improvement comprises:
- a circuit for maintaining substantially constant a horizontal dimension of an image displayed by the display apparatus independently of changes in a dwell time of the input video signal,
- said circuit including:
- means for detecting the horizontal sync frequency of the video signal;
- generating means for generating first and second different control voltages which depend on the detected horizontal sync frequency,
- said generating means including first means for generating said first control voltage as a first function of the detected horizontal sync frequency and second means for generating said second control voltage as a second function of the detected horizontal sync frequency, said first and second means differing from each other for generating said first and second control voltages as different functions of the detected horizontal sync frequency;
- wherein said second means of said generating means comprises means for storing predetermined voltage levels of said second control voltage corresponding to predetermined horizontal sync frequencies and means for interpolating voltage levels for horizontal sync frequencies between said predetermined horizontal sync frequencies,
- a variable horizontal oscillator oscillating at a frequency dependent on said first control voltage;
- and
- a horizontal output circuit responsive to said second control voltage for generating a horizontal deflection current which is synchronous with an oscillation output signal from the variable horizontal oscillator,
- wherein said second means of said generating means generates said second control voltage to represent variation of dwell time, defined as a ratio of one video period TD to one horizontal period TH of the horizontal sync frequency, thereby to compensate for variations in amplitude of said horizontal deflection current in dependence on the horizontal sync frequency.
7 more elements
In a display apparatus for visualizing an input video signal having a changeable horizontal sync frequency, an improved horizontal deflection circuit, wherein the improvement comprises:
- a circuit for maintaining substantially constant a horizontal dimension of an image displayed by the display apparatus independently of changes in a dwell time of the input video signal,
- said circuit including:
- means for detecting the horizontal sync frequency of the video signal;
- generating means for generating first and second different control voltages which depend on the detected horizontal sync frequency,
- said generating means including first means for generating said first control voltage as a first function of the detected horizontal sync frequency and second means for generating said second control voltage as a second function of the detected horizontal sync frequency, said first and second means differing from each other for generating said first and second control voltages as different functions of the detected horizontal sync frequency;
- wherein said generating means comprises means for storing predetermined voltage values of said first and second control voltages corresponding to said first and second functions of predetermined horizontal sync frequencies, and means for interpolating voltage values for horizontal sync frequencies between said predetermined horizontal sync frequencies in accordance with said first and second functions, and wherein said first and second means include respective first and second converting means for converting interpolated voltage values to said first and second control voltages,
- a variable horizontal oscillator oscillating at a frequency dependent on said first control voltage;
- and
- a horizontal output circuit responsive to said second control voltage for generating a horizontal deflection current which is synchronous with an oscillation output signal from the variable horizontal oscillator.
6 more elements
In a display apparatus for visualizing an input video signal having a changeable horizontal sync frequency, an improved horizontal deflection circuit, the improvement comprising:
- a circuit for maintaining substantially constant a horizontal dimension of an image displayed by the display apparatus independently of changes in the horizontal sync frequency of the input video signal,
- said circuit including:
- means for detecting the horizontal sync frequency of the video signal;
- generating means for generating first and second different control voltages which depend on the detected horizontal sync frequency,
- said generating means including first means for generating said first control voltage as a first function of the detected horizontal sync frequency and second means for generating said second control voltage as a second function of the detected horizontal sync frequency, said first and second means differing from each other for generating said first and second control voltages as different functions of the detected horizontal sync frequency,
- said second means of said generating means including:
- means for storing predetermined voltage levels of said second control voltage corresponding to predetermined horizontal sync frequencies,
- means for interpolating voltage levels for horizontal sync frequencies between said predetermined horizontal sync frequencies, and
- means for converting the interpolated voltage levels to said second control voltage;
- a variable horizontal oscillator oscillating at a frequency dependent on said first control voltage;
- and
- a horizontal output circuit responsive to said second control voltage for generating a horizontal deflection current which is synchronous with an oscillation output signal from the variable horizontal oscillator.
9 more elements
Dependencies are inferred from the claim text.