JPS603262B2 - Color sub-modulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color sub-modulator with a digital configuration used mainly to display characters and graphics on an NTSC color television receiver, and in particular to a color sub-modulator that increases the level of the rising edge of a color display signal. This invention relates to a color drama modulator that improves color coverage at edge portions of a display.

In recent years, with the rapid development of electronic technology, various circuits are being digitized, and the applicant has proposed a digitized color sub-modulator used to display characters and figures. (Title of the invention: "Color Sub-Modulator" Tsubakiwaki No. 53-164955). This oscillates a continuous signal having a frequency six times that of the color subcarrier, counts this oscillation output with a ternary counter, and counts the count output with a binary counter, thereby obtaining a period six times the frequency of the oscillation output. Generate a symmetrical square wave signal with Next, the output signal of this binary counter is supplied to a 6-stage shift register, and the oscillation output is used as a clock to sequentially shift the output signal to 0. obtain a symmetric square wave signal. The parallel output of this shift register is taken out as a symmetrical square wave pseudo carrier color signal corresponding to the green and cyan phases of the carrier color signal from the 3rd and 6th stage outputs. The outputs of the five stages are outputted with a delay of about 1 sec through an AND gate, respectively, and are taken out as a symmetrical square wave pseudo carrier color signal corresponding to the blue, cyan, yellow, and red phases of the carrier color signal. The six types of pseudo carrier color signals generated in this way that approximate the phases of the carrier color information of the three primary colors and their complementary colors used in NTSC broadcasting correspond to the six types of color display signals. Then, only one type of pseudo carrier color signal is extracted. In this case, if a symmetrical square wave signal with a phase corresponding to color data is simply extracted and used as a pseudo carrier color signal, then the rising part of the color display signal in the horizontal scanning direction relative to the character or figure display, that is, the edge part of the character or figure display. The color paste becomes dull.

In view of the above points, the present invention has been made to solve such problems and eliminate such drawbacks. An object of the present invention is to provide a color sub-modulator which obtains a pseudo carrier color signal by selecting corresponding to the color sub-modulator, which can improve the color coverage at the edge portion of the display (twill points).

In order to achieve such an object, the present invention provides an achromatic color detection means for detecting an achromatic color such as white or black from a color display signal that controls a display color in accordance with the display color of a character/figure display; a first level raising means for increasing the output obtained by the color detection means to a predetermined level higher than the low level during the achromatic period; a delay means for delaying by 1 bit; and 1 bit corresponding to the color specified by the color display signal.
second level raising means for raising the level of a period including at least the first bit changing from an achromatic color to a chromatic color based on a selected output of the symmetrical square wave signal of the species and the output obtained by the delay means; This is how it works.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.
FIG. 1 is a circuit diagram showing an embodiment of a color sub-modulator according to the present invention, and here, like a well-known character color display device, characters and figures displayed on the screen are separated into pixel units. Image data for controlling brightness is read out from a brightness control memory (not shown) in units of screen lines, and a color display signal (hereinafter referred to as color data) for controlling the display color corresponding to the display color of each bright spot is shown in the figure. A device that inputs a parallel 3-bit display signal which is read out in synchronization with the brightness control memo IJ from the color control memory (not shown) and which is a combination of data from both memories will be described. In the same figure, 1 is the subcarrier frequency fs in the NTSC system.
c (approximately 3. MHz) six times the frequency (approximately 21.48 MHz)
The oscillation circuit 2 uses the output of the oscillation circuit 1 to continuously oscillate at a subcarrier frequency fsc, and the phase corresponds to the carrier color signal blue, cyan, green, yellow, red, and magenta. Phase symmetric square wave signals SCB, SCC, SCG
, SCY, SCR, SCM and pseudo color burst signal B
a symmetrical square wave signal generation circuit that digitally generates ST;
3 is a symmetrical square wave signal SCB, SCC, SCG, SCY, SCR corresponding to a total of six colors, three primary colors and their complementary colors, among the seven types of signals output from the symmetrical square wave signal generation circuit 2.
, SCM input and parallel 3-bit pulse color data CD supplied corresponding to the color of the character and graphic display, ~
CD3 is connected to inverter 4a. 4c as a selection signal, and this symmetrical square wave selection circuit 3 receives color data CD, ~CD for one koji point.
3, one of the six types of symmetrical square wave signals corresponding to the color specified by the color data CD, to CD3 is selected and output. 5 is an AND gate which inputs the color burst signal BST outputted from the symmetrical square wave signal generation circuit 2 and the color burst flag pulse CBF produced by a well-known synchronization signal generation circuit (not shown) and extracts the color burst signal BST; 6 is an AND gate for extracting the color burst signal BST; An inverter 7 inverts the color burst flag pulse CBF, and a decoder 7 inputs color data CD, to CD3 via inverters 4a to 4c.
When ~CD3 becomes "11r" and represents black, the output terminal Qo becomes "0", and the color data CD, ~CD3
When becomes "00" and represents white, the output terminal Q, becomes "
0'', and when any of the color data CD. to CD3 becomes 0 to represent a certain color, one of the corresponding output terminals Q, to Q6 becomes a small 0''.

8 is a NAND gate which inputs the signals outputted from the output terminals Qo and Q7 of the decoder 7, and which inputs the signals outputted from the output terminals Qo and Q7 of the decoder 7;
~Outputs a "1" signal only when CD3 specifies black or white.

The inverters 4a to 4c, the decoder 7, and the NAND gate 8 are connected to color display signals (color data CD, to CD
3) constitutes an achromatic color detection means for detecting an achromatic color such as white or black. Reference numeral 9 denotes a NAND gate which receives the signals outputted from the output terminals Q, .about.Q6 of the decoder 7, and outputs a "1" signal only when the color data CD, .about.CD3 specifies a color other than black or white.

101 is a delay circuit which connects the inverters 10a to 10g in series and delays the output of the NAND gate 9 by one bit of image data;
1 bit of the image data is output from the rising edge of the output of , and the delay circuit 10 and the AND gate 11 constitute a circuit that extracts 1 bit of the rising edge of the color data CD, to CD3. .

The NAND gate 9, the delay circuit 10, and the AND gate 11 are connected to the color display signal (color data CD, . . .
A delay means is configured to detect a chromatic color other than white or black from the CD 3) and delay it by one bit of image data. 13 is an AND gate for matching the output of the symmetric square wave signal selection circuit 3 and the output of the AND gate 11; 14 is a resistor for connecting the output of the symmetric square wave signal selection circuit 3, the AND gate 5, the inverter 6, the NAND gate 8, and the AND gate 13; 14a~
14e, and this combined signal is sent to transistor 1.
This is the first mixing circuit that outputs the output via 4f.

The resistor 14a of the first mixing circuit 14 constitutes a first level increasing means for raising the achromatic color period to a predetermined level higher than the low level based on the output obtained by the achromatic color detecting means, Further, the resistor 14e is connected to the color display signal (
Color Data CO. ~CD3) Based on the selected output of one kind of symmetrical square wave signal corresponding to the color specified by CD3) and the output obtained by the delay means, a period level including at least the first one bit that changes from an achromatic color to a chromatic color. This constitutes a second level increasing means. The outer terminal of this transistor 14f is connected to the power supply +B, and the outer emitter thereof is connected to the power supply -B via a resistor 14g.
15 is a band pass filter connected to the output device of the first mixing circuit 14; 16 is a band pass filter 16 which inputs color data CD, to CD3, and corresponds to the display color for the rope dots of characters and figures;
Depending on the color and two colors corresponding to white and black, a total of 8 colors, NT
This is an addition circuit that outputs a luminance signal converted into eight luminance levels based on a standard luminance signal in the SC system, and includes inverters 16a to 16c that invert each bit signal of color data CD, to CD3, respectively, and each inverter. A resistor 16d for combining the outputs of 16a to 16c, respectively.
The transistor 16g has a base input via a transistor 16f.

The collector of this transistor 6g is connected to the power supply +B, and the emitter is connected to the power supply -B via a resistor 16h. 17 is a low-pass filter connected to the output end of the adder circuit 16; 18 is a pseudo carrier color signal and a pseudo burst signal, which will be described later, output from the band-pass filter 15; a luminance signal output from the low-pass filter 17; and a synchronization signal (not shown). The synchronization signal SYN supplied from the signal generation circuit is synthesized to generate an NTSC composite video signal BS.
This is a second mixing circuit that outputs .

The operation will be explained below using waveform diagrams of each part. First, as shown in FIG. 2a, the oscillation circuit 1 generates a clock pulse CKP having a frequency six times the subcarrier frequency fsc.
is output continuously. This clock pulse CKP is applied to a ternary counter 2a constituting the symmetrical square wave signal generation circuit 2.
The output is the pulse signal QB shown in FIG. 2b. The pulse signal QB output from the ternary counter 2a is frequency-divided by 2 in the flip-flop 2b constituting the binary counter, and as shown in FIG. Output.

This symmetrical square wave signal Qc is input to a shift register 2c having a six-stage configuration, and is sequentially shifted by a clock pulse CKP, so that the shift register 2c is outputted to the output terminals Q^~QF of each stage as shown in FIG. 2 d~i. It outputs waveform signals, that is, six-phase signals of symmetrical square wave signals A to F having a subcarrier frequency fsc and whose phases are shifted by 60 degrees. In this case, if the six phases are equally divided by 60 degrees as in the output of the shift register 2c, a symmetrical square wave signal is output from the output terminal Qo (Fig. 2g) of the fourth stage of the shift register 2c. D phase is NTSC
This is the closest phase to the color burst signal used in broadcasting. Therefore, this symmetric square wave signal D
is output as a pseudo color burst signal BST. Also, the output terminals Q of the third and sixth stages of the shift register 2c
In order to approximate the phases of green and magenta of the carrier color signal, the symmetrical square wave signals C, F (FIG. 2 f, i) outputted from C and QF are converted into symmetrical square wave signals SCG, SCG, corresponding to the carrier color signals. S.C.
Output as M. Furthermore, the first,
2nd, 4th, 5th stage output machine Q^, Q8, Qo,
Symmetrical rectangular 0-wave signals A, B, D, and E output from QE are converted to 1 by passing through AND gates 2d to 2g, respectively.
Each output signal is delayed by about 10 seconds, and each output signal becomes a signal that approximates the blue, cyan, yellow, and red phases of the carrier color signal.
Therefore, the signals output from the AND gates 2d to 2g are output as symmetrical square wave signals SCB, SCC, SCY, and SCR (Fig. 2 i to m) having phases corresponding to the blue, cyan, yellow, and red. Then, the blue, cyan, green, yellow, and blue carrier color signals generated from the symmetrical square wave generation circuit 2 are
Each symmetrical square wave signal SCB approximates the phase of red and magenta
, S.C.C. SCG, SCY, SCR, and SCM are respectively input to a symmetrical square wave signal selection circuit 3, and the color data CD, to are supplied via inverters 4a to 4c.
One type of symmetrical square wave signal corresponding to the color specified by CD3 is selected and output. Here, following the color burst flag pulse CBF shown in FIG. 3h, color data CD, to CD3 as shown in FIG.
The operation when is input will be explained.

Note that a to g in Figure 3 are e, j, k, f, evening, m in Figure 2.
For convenience of explanation, the pulse width is shown narrower than in FIG. 2. First, in the period A shown in FIG. 3, since the color burst flag pulse CBF is generated, the AND gate 5 extracts the burst signal BST during this period, and the waveform shown in FIG. That is, it outputs "L" level during the display period.

Next, in the first and second periods of FIG. 3, since the color data CD, to CD3 shown in FIG. The output, that is, the "L" level is output, and the viewpoint on the screen is displayed as black. In addition, during the period shown in FIG. Display the upper foot point as white. Next, in the second period, since the color data CD, to CD3 become "HHr", the symmetrical square wave signal selection circuit 3 selects the symmetrical square wave signal SCY shown in FIG. 3a inputted to the input terminal D3. (period 2 of m in Figure 3). Similarly, in period e, the symmetrical square wave signal SCC supplied to the input terminal D6 is output.
is output, and a symmetrical square wave signal SCG is output during the period to
is output, and during the period G, a symmetrical square wave signal SCM
is output, and during period H, a symmetrical square wave signal SCR is output.
is output, and in the period ri, a symmetrical square wave signal SCR
is output (Fig. 3 m). On the other hand, since the inverter 6 inverts the color burst flag pulse CBF, it sends out the output shown in FIG. 3n. In addition, the naso gate 8 is connected to the output terminal of the decoder 7 or when Q7 is “L”.
” state, that is, the period in which black or white is being displayed as described above, the "H" level output shown in FIG. The NAND gate 9 that receives the output signal outputs a "1" signal only when any of the color data CD, to CD3 is "1", that is, when a color other than black or white is specified. Color data CD, ~CD shown in Figures i-k
3, it becomes "1" in the period from 2 to 3, as shown in FIG. 3, p.

The output signal of this NAND gate 9 is delayed by one bit of image data in a delay circuit 1, and the output signal of this delay circuit 10 and the output signal of the NAND gate 9 are delayed in an AND gate 11.
By determining the match of the outputs, the AND gate 1
As shown in FIGS. 1 to 3q, a signal corresponding to one bit of image data is obtained from the rising edge of the color data signal. The output of the symmetric square wave signal selection circuit 3 generated in this way (Fig. 3 m), the output of the AND gate 5 (Fig. 3 S), the output of the inverter 6 (Fig. 3 N), the output of the AND gate 13 (Fig. 3 N), and the output of the AND gate 5 (Fig. 3 N). Output (Fig. 3q) and output of NAND gate 8 (
3o) are combined through resistors 14a to 14e, respectively, and then amplified by transistor 14f and outputted as a waveform shown in FIG. 3r. In this case, during the color burst flag pulse CBF generation period,
Since the output of the inverter 6 becomes "L" level and the output of the inverter 6 becomes "H" level from the end of the color burst flag pulse CBF, the change in the output value of the inverter 6 is shown by arrows X and R in FIG. This appears as a change in the output of the first mixing circuit 14, as shown in FIG. As a result, the slave can now extract the color bust signal T, which could only be extracted up to the change up to arrow Y in Figure 3 r, as a change up to arrow X in Figure 3 r, and accordingly. Therefore, the phase reproducibility for the color burst signal BST is improved. In addition, since the NAND gate 8 generates a "H" level output only during the period when the color data CD, ~CD3 specifying black or white is supplied, it is possible to display black or white and other colors. At the boundary of the display, the output of the first mixing circuit 9 is changed as shown by arrows X2 and X3 in FIG. However, the phase detection range will be expanded to the points indicated by arrows X2 and X3, and the phase reproducibility will be improved accordingly.On the other hand, the output signal of the AND gate 11 is As shown in FIG. 3q, the color data CD, ~C
Since the signal corresponds to one bit of rising edge of D3,
The AND gate 13 generates a pulse-like output corresponding to one bit of the rising edge of the color data CD to CD3 only when the output of the symmetrical square wave signal generation circuit 2 is generated, and this output is passed through the resistor 14a of the first mixing circuit 14. and mixed with other signals.

As a result, as shown by the arrow Z in FIG. The output level increases over time. In this way, color data CO. - When the level of the carrier color signal rises at the rise of CD3, the rising portion, that is, the edge portion of the display pattern is particularly emphasized, and the whiteness in this portion is also improved accordingly.

The output of the first mixing circuit 14 containing the thus synthesized pseudo color bar signal and pseudo carrier color signal is output via the band pass filter 15 as a waveform shown in FIG. 3s.

On the other hand, the color data CD, to CD3 are processed by the inverter 16a.
~16c is also input and inverted, and this inverted output is added by resistors 16d~16f.

In this case, the resistance values of the resistors 16d to 16f are set to correspond to the luminance level corresponding to each color in the NTSC signal. This added signal is output to the low-pass filter 17 via an emitter follower composed of a transistor 16g and a resistor 16h. Therefore, when color data CD, -CD3 as shown in FIG. 3 i to k are input, a luminance signal shown in FIG. The outputs of these filters 15 and 17 are the synchronizing signal SYN output from a synchronizing signal generating circuit (not shown), and the synchronizing signal SYN is output from the second mixing circuit 18.
The signals are mixed in the NTSC system and outputted as a subsequent video signal of the NTSC system as shown in FIG. 3(u). Therefore, by modulating this subsequent video signal using a well-known RF modulator, characters and graphics can be displayed in color on empty channels of a general television receiver. In this case, because the level of the carrier color signal is raised in the part where the color changes from white or black to another color, the voiced mark is generally not displayed even if the signal is received using the bandwidth of the receiver. Improves color coverage at edges. In the above embodiment, only the case where the signal level is increased during the period corresponding to one bit of image data at the rise of the carrier color signal to emphasize that part has been described, but the present invention is not limited to this. It goes without saying that the emphasis may be emphasized over a period of multiple bits (2 to 3). As described above, the color sub-modulator according to the present invention obtains a carrier color signal by selecting a phase-shifted symmetric square wave signal and a color display signal in correspondence with each other. When the color display signal changes to a color display signal specifying another color, the level of the carrier color signal is increased for a predetermined period of time at the rising edge of the color display signal. This has an excellent effect of improving color coverage at the edge portion of the dot displayed on the screen when a signal is received.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of a color sub-modulator according to the present invention, and FIGS. 2 and 3 are diagrams showing operating waveforms of each part of the circuit shown in FIG. 1. DESCRIPTION OF SYMBOLS 1... Oscillation circuit, 2... Symmetrical square wave signal generation circuit, 3... Symmetrical square wave signal carrier circuit,
4a to 4c...Inverter, 5...And gate, 6...
...Inverter, 7...Decoder, 8, 9...NAND gate, 10...Delay circuit, 11, 13...
・AND gate, 14...First mixing circuit, 14
d, 14e...Resistor, 15...Band pass filter, 16...Addition circuit, 17...
...Low pass filter, 18...Second mixing circuit. Figure Vertical Figure 2 Figure 3

Claims (1)

[Claims] 1 Color sub-modulator that obtains a carrier color signal by selecting a phase-shifted symmetrical square wave signal corresponding to the color display signal, and a color display that controls the display color corresponding to the display color of the character/graphic display. an achromatic color detection means for detecting an achromatic color such as white or black from a signal; and a first level raising means for raising the achromatic period to a predetermined level higher than a low level based on the output obtained by the achromatic color detection means. Then, a chromatic color other than white or black is detected from the color display signal and one of the image data is detected.
a delay means for delaying by a bit, a selected output of one type of symmetric square wave signal corresponding to the color specified by the color display signal, and at least one color changing from an achromatic color to a chromatic color based on the output obtained by the delay means; and second level raising means for raising the level in a period including the first one bit.