JPH0771229B2 - Color super circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color super circuit for reducing flicker occurring near a boundary of a character signal in a color super circuit in which a character is embedded in a background in a television broadcasting station or the like. .

[Prior Art] The coloring and embedding of characters, which is called a color super circuit, is performed by the circuit shown in FIG. In FIG. 5, the original input of the NTSC signal is input from the terminal 1, the character signal is imaged by a black and white telop camera, and input from the terminal 2. For example, when an image of a character "character" is picked up at the terminal 2 as shown by a raster frame and the "character" is colored white at the output terminal 10 and its contour is colored, first the slice circuit 3 causes the character "character" to appear. A signal obtained by slicing the signal in the shape of is obtained. Next, in order to obtain the contour portion, the signal generator 4 of the contour portion delays by using a delay circuit in the horizontal and vertical directions to expand the pulse width. Then, the gate circuit 5 punches out the character "character" to obtain a binarized key signal.
Next, the output of the 3.58 MHz color subcarrier oscillator 7 is set up by a predetermined level by an adder 8 and then gated by the key signal in a gate circuit 6 to generate a coloring range. The signal in this coloring range is set in the fitting circuit 9
Input to the NTSC original signal (background signal). The character signal is also input to the fitting circuit 9 as the output of the slice circuit 3 and fitted into the coloring range. The coloring color is determined by the output signal phase of the color subcarrier oscillator 7. A signal obtained by the so-called color super circuit configured as described above is output to the terminal 10.

[Problems to be Solved by the Invention] When white characters are embedded in a colored background by the circuit configuration described above, the 3.58 MHz signal is sharply cut off at the boundary of the colored range, resulting in a boundary of the generated color signal. The frequency band in the department has exceeded the band specified by the NTSC system. FIG. 6 is a diagram showing a signal waveform of a horizontal scanning line with respect to a white character and a contour boundary portion. Since the signal of 3.58 MHz following the white character rises extremely steeply, its envelope can be regarded as a rectangular wave.

Also, by sending an image of the characters embedded by this circuit configuration,
When the image was received by an ordinary receiver, the luminance / color signal separation circuit did not operate normally, and the 3.58 MHz signal at the colored boundary portion was mixed into the luminance signal, resulting in flicker.

Regarding the operation of the luminance / color signal separation circuit, a three-dimensional luminance / color signal separation circuit is provided in the EDTV receiver, and if this circuit contains a 3.58MHz signal mixed in the luminance signal,
Since it was judged as a "moving signal" and it operated as a two-dimensional luminance / color signal separation circuit, the circuit at a corner did not operate as an appropriate three-dimensional circuit, resulting in deterioration of image quality.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color super circuit in which the above-mentioned drawbacks are remedied, a waveform shaping circuit is inserted in the circuit structure, and the occurrence of flicker at the colored boundary is reduced.

[Means for Solving the Problems] FIG. 1 is a diagram showing a principle configuration of the present invention. In FIG. 1, 1 is an original input terminal of NTSC signal, 2 is a character signal input terminal, 3 is a slice circuit, 4 is a circuit for widening a pulse width, 5,
6 is a gate circuit, 7 is a color subcarrier oscillator, 9 is a fitting circuit, 10 is a signal output terminal, and 11 is a waveform shaping circuit.

The color subcarrier signal is gated by the key signal obtained by slicing the character signal input from the input terminal 2 by the slicing circuit 3 and widening the pulse width by the circuit 4 to create the signal of the contour portion, and the obtained coloring The present invention has the following configuration in a color super circuit in which a signal is embedded in the background signal from the terminal 1. That is, the waveform shaping circuit 11 for inclining the rising and falling waveforms in the horizontal and vertical directions of the key signal is inserted in the preceding stage of the color subcarrier gate circuit 6.

[Operation] When a white "character" is fitted to the screen with a colored background, a character signal is input from the input terminal 2 as in the conventional case, and the slice circuit is used.
3. The "character" key signal obtained through the circuit 4 for expanding the pulse width is input to the waveform shaping circuit 11. The circuit performs an operation of giving a slope to each of the rising and falling waveforms in the horizontal and vertical directions of the key signal. Therefore, the output waveform of the waveform shaping circuit 11 does not have steep rises and falls. With respect to the signal, the output of the color subcarrier oscillator 7 is fitted into the screen through the gate circuits 6 and 9 and output to the output terminal 10. Even when the image is transmitted based on this signal and received by an ordinary image receiver, the flicker does not occur in the character outline portion.

[Embodiment] FIG. 2 shows an embodiment of the present invention with respect to a horizontal signal of the waveform shaping circuit 11 shown in FIG. Fig. 2 shows a low-pass filter with a cutoff frequency of about 1.5MHz.
The cutoff characteristic is similar to the characteristic of the color signal in the NTSC system, especially for the I signal. Therefore, the signal passing through the circuit having the characteristic shown in FIG. 2 has a very small signal amplitude at high frequencies of 1.5 MHz or more, and has a waveform as a slope.

Next, the waveform shaping circuit for the vertical direction signal uses the two-dimensional comb filter shown in FIG. In Figure 3, 1H
Is a delay circuit for delaying by a horizontal scanning period, and is usually used for color signal separation by inputting a composite color signal to the input side. When a rectangular wave signal is applied to this circuit, the vertical waveform is not steep.

FIG. 4 is a diagram showing horizontal waveforms when the color subcarrier is gated by the signal waveforms passing through the circuits of FIGS. 2 and 3. The signal having this waveform is fitted into the original signal by the fitting circuit 9 in FIG. 1, so that the received signal has no flicker.

[Effects of the Invention] According to the present invention as described above, by inserting the waveform shaping circuit, the rising and falling edges of the color subcarrier signal of the color super circuit are inclined. Therefore, flicker is less likely to occur in the colored boundary portion between the characters on the image receiving screen and the background, and the image quality is improved. This is especially effective in an EDTV receiver because the three-dimensional luminance / color signal separation circuit operates properly.

[Brief description of drawings]

FIG. 1 is a diagram showing a principle configuration of the present invention, FIG. 2 is a diagram showing characteristics of a waveform shaping circuit, FIG. 3 is a diagram showing a configuration example of a waveform shaping circuit, and FIG. 4 is a color subcarrier according to the present invention. FIG. 5 is a diagram showing an example of a signal, FIG. 5 is a configuration diagram of a conventional color super circuit, and FIG. 6 is a waveform diagram of a color subcarrier signal in FIG. 1 …… NTSC background signal input terminal 2 …… Character signal input terminal 7 …… Color subcarrier oscillator 9 …… Inset circuit 10 …… Signal output terminal 11 …… Wave shaping circuit

Claims (3)

[Claims] 1. A color subcarrier signal is gated by a key signal obtained by slicing a character signal, then widening a pulse width to create a contour signal, and fitting the obtained colored signal into a background signal. In the color super circuit for performing the above, a color shaping circuit for inclining the rising and falling waveforms of the key signal in the horizontal and vertical directions is inserted in the preceding stage of the color subcarrier gate circuit. circuit. 2. The horizontal waveform shaping circuit according to claim I approximates a rectangular wave signal that has passed through a low-pass filter (cutoff frequency 1.5 MHz) based on the NTSC I signal standard. A color super circuit characterized by being configured with a circuit having a characteristic of obtaining a waveform. 3. A vertical waveform shaping circuit according to claim 1 is a circuit having a characteristic that a waveform approximate to a rectangular wave signal passed through a low-pass type two-dimensional comb filter circuit is obtained. A color super circuit characterized by being configured.