Apparatus for digitally controlling pal color display

Claim 2

In an apparatus for use with a phase alternation line video display adapted to receive color signals having a color subcarrier reference signal of frequency N, an improved color signal generation means comprising: means for generating at least one digital word which corresponds to a predetermined color, said digital word comprising a plurality of bits; storing means for storing said digital word; circuit means for providing an odd/even signal representative of odd and even lines on said display; sampling means coupled to said storing means for sequentially sampling each of said bits of said digital words at a predetermined sampling rate in a first sequence and a second sequence opposite to said first sequence, said first and second sequences being selected according to said odd-even signal and said predetermined sampling rate being selected such that a color signal is developed at an output of said sampling means which corresponds to said predetermined color and which has a frequency component at said frequency N; whereby a color signal suitable for use with a phase alternation line video display is generated.

Claim 3

The color signal generation means of claim 1 wherein said sampling means includes bit selecting means for controlling which of said bits is sampled in the beginning of said first and second sampling sequences.

Claim 4

The color signal generation means of claim 2 wherein said sampling means is a recirculating shift register means having a plurality of stages for receiving said digital word from said storing means and for circulating said digital word at said predetermined sampling rate in a first direction which corresponds to said first sampling sequence, and a second direction which corresponds to said second sampling sequence.

Claim 5

The color signal generation of claim 3 wherein said bit selecting means comprises a multiplexing means for selectively coupling one of said stages of said shift register means to said output.

Claim 6

The color signal generation means of claim 4 wherein said selective coupling of said multiplexing means occurs in response to said odd-even signal.

Claim 7

The color signal generation means of claim 5 wherein said shift register means is comprised of P number of said stages and said predetermined sampling rate is at a frequency approximately equal to N×P.

Claim 8

The color signal generation means of claim 6 wherein said circuit means comprises a digital counter and said odd/even signal is derived from the least significant bit of said counter.

Claim 9

The color signal generation means defined by claim 6 wherein P is equal to four.

Claim 10

The color signal generation means of claim 8, wherein N is approximately 4.434 MHz and said predetermined sampling rate is approximately 17.734 MHz.

Claim 11

The color signal generation means of claim 9 wherein said at least one digital word and said corresponding predetermined color comprise the following: ______________________________________ Digital word Corresponding Color ______________________________________ 1100 Blue 0110 Red ______________________________________

Claim 12

In an apparatus for use with a phase alternation line video display adapted to receive color signals having a color subcarrier reference signal of frequency N and where said apparatus provides a predetermined number of characters at least in the horizontal direction on said display, an improved color signal generation means comprising: means for generating at least one digital word which corresponds to a predetermined color, said digital word comprising P number of bits; storing means for storing said digital word; first circuit means for providing an odd/even line signal representative of odd and even lines on said display; second circuit means for providing an odd/even character signal representative of odd and even characters on said display; sampling means coupled to said storing means for sequentially sampling each of said bits of said digital word at a sampling rate approximately equal to N×P in a first sequence and in a second sequence opposite to said first sequence, said first and second sequences being selected according to said odd/even signal, with said sampling means further including a bit selecting means responsive to said odd/even line signal and said odd/even character signal for controlling which of said bits is sampled in the beginning of said first and second sampling sequences; whereby a color signal suitable for use with a phase alternation line video display is generated at an output of said sampling means.

Claim 13

In an apparatus for use with a phase alternation line video display adapted to receive color signals having a color subcarrier reference signal of frequency N and where said apparatus provides a predetermined number of characters at least in the horizontal direction on said display, an improved color signal generation means comprising: means for generating at least one digital word which corresponds to a predetermined color, said digital word comprising P number of bits; storing means for storing said digital word; first circuit means for providing an odd/even line signal representative of odd and even lines on said display; second circuit means for providing an odd/even character signal representative of odd and even characters on said display; sampling means coupled to said storing means for sequentially sampling each of said bits of said digital word at a sampling rate approximately equal to N×P in a first sequence and in a second sequence opposite to said first sequence, said first and second sequences being selected according to said odd/even signal, with said sampling means further including a bit selecting means responsive to said odd/even line signal and said odd/even character signal for controlling which of said bits is sampled in the beginning of said first and second sampling sequences; whereby a color signal suitable for use with a phase alternation line video display is generated at an output of said sampling means.

Claim 14

The color signal generation means of claim 11 wherein said sampling means comprises a recirculating shifter register means having P number of stages for receiving said digital word from said storing means and for circulating said digital word at said predetermined sampling rate in a first direction which corresponds to said first sampling sequence and a second direction which corresponds to said second sampling sequence and wherein said bit selecting means comprises a multiplexer having a plurality of inputs coupled to said stages of said shift register means and a multiplexer output coupled to said sampling means output.