Apparatus and method for digital deflection processing

A phase difference detecting apparatus in a digital deflection processing apparatus for a cathode ray tube, for digitally performing deflection processing using a system clock signal, comprising:

• phase difference detecting means for dividing a period of the system clock signal into N sections, where N is an integer not less than 2, for detecting a section to which a comparison signal non-synchronized with the system clock signal is input among the N divided sections, and for outputting the value assigned to the detected section as the decimal value of a phase difference between a reference signal synchronized with the system clock signal and the comparison signal;
• second phase difference detecting means for detecting the integer value of the phase difference using the system clock signal and the reference signal, and outputting the decimal value and the integer value in response to the system clock signal and the comparison signal;
• and
• a loop filter for stabilizing the jitter of the integer value using the filtered decimal and outputting the integer value, the jitter of which is stabilized and which is filtered, as the phase difference.

A window forming method performed in a window forming portion of a digital deflection processing apparatus for a cathode ray tube, having a counter for performing counting in response to a counting signal and being reset in response to a jitter-stabilized synchronous signal, the window forming portion for outputting the maximum values and the minimum values of standard, increase, and decrease windows, corresponding to count values (TK) counted by the counter, where 1≦K≦i, and where i is an integer not less than 2, a mode determining portion for comparing the maximum and minimum values with the point at which a jitter-unstabilized synchronous signal is generated and determining a mode corresponding to the comparison result, and a synchronous signal generating portion for generating a jitter-stabilized synchronous signal is corresponding to the determined mode, for digitally performing deflection processing comprising the steps of:

• determining a maximum value (Tmax) and a minimum value (Tmin) among the counted values;
• obtaining a subtraction value by subtracting the minimum value (Tmin) from the maximum value (Tmax);
• subtracting a result obtained by dividing the subtraction value by a first predetermined number from the minimum value (Tmin), adding the result obtained by dividing the subtraction value by the first predetermined number to the maximum value (Tmax), and determining the subtraction and addition results as the minimum value (Wmin) and the maximum value (Wmax) of the standard window, respectively;
• determining the (Wmin) as the maximum value (Wmax′) of the decrease window;
• determining a second predetermined number as the minimum value (Wmin′) of the decrease window;
• and
• determining third and fourth predetermined numbers, respectively, as the maximum value (Wmax″) and the minimum value (Wmin″) of the increase window.

An interpolation value calculating method performed in an interpolation value calculating portion in a digital deflection apparatus for a cathode ray tube, for calculating the interpolation values of the X and Y axis coordinate values of a beam using distortion correcting functions [F(X) and F(Y)], comprising the steps of:

• restricting the size of the X and Y axis coordinate values;
• obtaining lagrange functions [f0(X) through fn(X) and f0(Y) through fn(Y)] comprising an nth order polynomial with respect to the X and Y axis coordinate values, by a time division method;
• determining whether the seed values s0 through sn of a currently scanned line are externally provided;
• obtaining internal seed values when the seed values are not externally provided;
• obtaining distortion correcting functions using the seed values and the lagrange functions represented by:
• F(X)=s0f0(X)+s1f1(X)+ . . . +snfn(X)
• and
• F(Y)=s0f0(Y)+s1f1(Y)+ . . . +snfn(Y);
• and
• calculating the interpolation values with respect to the X and Y values by substituting the X and Y values for the distortion correcting functions.

An interpolation value calculating apparatus in a digital beam deflection processing apparatus for a cathode ray tube comprising:

• means for restricting the sizes of the X and Y coordinate values of the beam;
• means for calculating lagrange functions based on the X and Y values;
• means for calculating distortion correcting functions using the lagrange functions, represented by:
• F(X)=s0f0(X)+s1f1(X)+ . . . +snfn(X)
• and
• F(Y)=s0f0(Y)+s1f1(Y)+ . . . +snfn(Y)
• where, s0 through sn represent seed values and fo(X) through fn(X), and f0(Y) through fn(Y) represent lagrange functions;
• and
• means for calculating interpolation values with respect to X and Y by substituting X and Y for the distortion correction functions.