JP2643929B2 - Video signal synthesizer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal synthesizing apparatus, and more particularly to a video signal synthesizing apparatus, in which a plurality of composite video signals are input simultaneously, and one of the input composite video signals is used as a main screen, and And an apparatus for obtaining a composite video signal representing a composite screen inserted into the main screen with the sub-screen being a reduced screen.

[Conventional technology]

FIG. 2 is a block diagram showing a video signal synthesizing apparatus for obtaining a so-called picture-in-picture signal as a composite video signal, which is described in, for example, a color television textbook edited by the Japan Broadcasting Corporation (above), p.33. A color bar signal of the NTSC standard that visually displays the same pattern on both the main screen and the sub-screen is combined with a screen with a reduced sub-screen inserted near the center of the main screen (see FIG. 3 (a)). (Fig. 3 (b)
Reference). In this conventional example, the sub-screen is 1
This shows the case where the number is one.

In FIG. 2, reference numeral 11 denotes a first input terminal to which a first composite video signal serving as a main screen is input, 12 denotes a first YC separator, 13
Is a first chroma (color signal) demodulator, 14 is a first synchronizing signal separator, 15 is a second input terminal to which a second composite video signal serving as a sub-screen is input, and 16 is a second YC A separator, 17 is a second chroma (color signal) demodulator, 18 is a second synchronizing signal separator, 1
Reference numerals 9, 20, and 21 denote first, second, and third AD converters (analog-to-digital converters), and reference numerals 22, 23, and 24 denote writing and reading at the same time and at mutually asynchronous timing. The second and third digital memories 25, 26 and 27 are the first, second,
A third DA converter (digital-to-analog converter),
28 is an analog switch, 29 is a chroma (color signal) modulator,
30 is a YC adder, 31 is an output terminal, and 32 and 33 are first and second digital signal processing controllers.

Next, the operation will be described. The first composite video signal input from the first input terminal 11 is separated by the first YC separator 12 into a first luminance signal 34 and a first chrominance subcarrier signal 35. The first chrominance subcarrier signal 35 is converted by the first chrominance signal demodulator 13 into a first red difference signal 36 and a first blue difference signal.
Demodulated to 37.

On the other hand, the second composite video signal input from the second input terminal 15 is separated into a second luminance signal 38 and a second chrominance subcarrier signal 39 by the second YC separator 16. The second chrominance subcarrier signal 39 is demodulated by the second chrominance signal demodulator 17 into a second red color difference signal 40 and a second blue color difference signal 41.

The first, second, and third AD converters 19, 20, and 21 convert the second luminance signal 38, the second red difference signal 40, and the second blue difference signal 41 into digital signals, respectively. The data is written to the second and third digital memories 22, 23 and 24. At this time, the first digital signal processing system controller 32 generates the first and second control signals 42 and 43 necessary for the write control, but these timings are separated by the second synchronization signal separator 18. Sync signal
44, that is, in synchronization with the second composite video signal which is a sub-screen.

When reading the contents from the first, second, and third digital memories 22, 23, and 24, the sub-screen is reduced, that is, compressed in the time direction. In the time direction compression, the speed of scanning the contents of the digital memory at the time of reading is k times (k>) at the time of writing.
This can be realized by 1), whereby the digital signal is compressed to 1 / k in the time direction. The digital signal compressed in the time direction is converted into an analog signal by the first, second, and third DA converters. After passing through the digital signal processing system, the second luminance signal 38, the second red difference signal 40, and the second blue difference signal 41 are time-compressed into a third luminance signal 45 and a third red difference signal 46, respectively. , The third blue difference signal
Converted to 47.

Here, the third and fourth control signals 48, 4 necessary for reading
9 is generated by the second digital signal processing system controller 33.
Are synchronized with the separated synchronizing signal 50, that is, synchronized with the first composite video signal which is the main screen. Naturally, the obtained third luminance signal 45, third red difference signal 46, and third blue difference signal 47 are also synchronized with this.

The analog switch 28 is used for time division multiplexing of the main screen and the time-compressed sub-screen, and the switching command signal 51 of the analog switch 28 has a timing synchronized with the main screen. The result of time division multiplexing of the analog switch 28 is
Since the signals are separated into a luminance signal, a red color difference signal, and a blue color difference signal, a color subcarrier is generated in the color signal demodulator 20 and then added to the luminance signal in the adder 30 to obtain a desired composite video signal. At the output 31.

[Problems to be solved by the invention]

Since the conventional video signal synthesizing apparatus is configured as described above, it is necessary to perform chroma demodulation and chroma modulation even on the main screen which does not need to perform time compression, which causes deterioration of image quality. Further, three systems of analog switches for time division multiplexing are required, which has a drawback such as a large cost factor when the number of sub-screens is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is possible to eliminate the deterioration of the image quality of the main screen and to reduce the cost by reducing the cost by using only one analog switch regardless of the number of sub-screens. The purpose is to obtain a synthesizer.

[Means for Solving the Problems] A video signal synthesizing apparatus according to the present invention provides a time axis compression for compressing a time axis of a component signal extracted from a first composite video signal inserted into a main screen and serving as a sub screen. Means,
Encoding means for synthesizing a second composite video signal from the component signal whose time axis has been compressed by the time axis compression means;
A carrier generating means for generating a carrier synchronized with the color subcarrier of the composite video signal, a frequency-voltage converter which receives the third composite video signal as input, and outputs a voltage corresponding to the frequency of the color subcarrier, and The third above
And a voltage control delay line whose delay time is controlled by a voltage output from the frequency-to-voltage converter, and a signal corresponding to the frequency of the color subcarrier of the third composite video signal. Delay the third
Delay means for giving the composite video signal of the second composite video signal, and selecting one of the second composite video signal and the third composite video signal delayed by the delay means in synchronization with the third composite video signal Switching means for selectively outputting the third composite video signal serving as the main screen without changing or demodulating the third composite video signal.
Time division multiplexing of the main screen and the sub-screen is performed in the state of the composite video signal.

[Action]

In the present invention, when the sub-screen is re-modulated by the carrier generation means, the carrier required for the chroma modulation circuit of the sub-screen is given as being synchronized with the color sub-carrier of the main screen, and the carrier is generated in the state of the composite video signal. Since time-division multiplexing of the main and sub-screens is performed, processing relating to chroma demodulation and chroma modulation of the main screen becomes unnecessary. Further, since a signal delay corresponding to the frequency of the color subcarrier of the third composite video signal is given to the third composite video signal, the phases of the color subcarriers of the main screen and the sub-screen match. That is, color matching between the main screen and the sub-screen is performed.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a video signal synthesizing apparatus according to an embodiment of the present invention. In FIG. 1, the same reference numerals as those in FIG. 2 denote the same components. 4 and 5 show a signal path of a first input terminal 11 to which a first composite video signal serving as a main screen is input, and a second signal path to which a second composite video signal serving as a sub-screen is input.
3 is a diagram showing waveforms of respective signals in a signal path of an input terminal 15 of FIG.

In the picture-in-picture apparatus, since the main screen signal and the sub-screen signal are presumed to be mutually asynchronous signals input from separate signal sources, the main screen signal and the sub-screen signal in one horizontal period are The respective signal waveforms are substantially the same as 11 in FIG. 4 (a) and 15 in FIG. 5 (a), however, the timings of the synchronization signals are shifted from each other, and the shift amount Δt Changes. More specifically with reference to FIG. 6, 11a of FIG. 6, 15a is a time t ₀
Main signal waveform and are those showing the timing relationship of the sub-signal waveform and 11b, 15b are mutual timing of the main signal waveform and auxiliary signal waveform at time t ₁ after a predetermined time has elapsed from the time t ₀ in It shows the relationship. From this figure, it can be seen that the shift amount Δt of the timing of the synchronization signal of each signal changes with time.

In FIG. 1, 52 is a PLL, 53 and 54 are first and second carriers for chroma modulation generated by the PLL 52, 55 is a frequency-voltage converter (hereinafter referred to as FV converter), and 56 is This is a voltage control delay line.

 Next, the operation will be described.

Color subcarrier of main signal 11 (first YC separator 12
First, the PLL 52 causes the color burst signal 11b of the main signal to be equal in frequency and reference phase so that the chroma signal 35) separated from the composite video signal of FIG. And the first and second carrier waves 53 and 54 having the same frequency and a phase difference of 90 degrees are obtained. First and second for chroma modulation
The carrier waves 53 and 54 have the same frequency as the color bust signal of the first main signal 11 and have a constant phase difference with respect to the color burst signal of the main signal.
The hue of the reduced sub-screen obtained by adding the chroma-modulated result 29a and the time-compressed luminance signal 45 of the sub-screen is shifted from the hue of the main screen by a fixed hue angle. For this reason, it is necessary to provide a delay means on the main screen signal side to make the hues of the main and sub screens coincide. That is, PLL5
2. A conversion voltage 57 corresponding to the frequency of the carrier wave 53 or 54 generated by 2 is generated by the FV converter 55, and the voltage control delay line inserted on the main signal side by the conversion voltage 57
The controller 56 controls the frequency and the reference phase of the color subcarrier of the main signal and the subsignal 58 at the input terminal of the analog switch 28. FIG. 7A shows an example of the input / output characteristics of the FV converter 55. A voltage value Δv proportional to the frequency displacement Δf is output from a reference frequency. FIG.
3B is a diagram showing an example of the input / output characteristics of the voltage control delay line 56, in which a delay time Δt proportional to the control voltage Δv is given to the main screen signal 11 and output. As described above, when the frequency of the color sub-carrier is shifted, the amount of time to be delayed for phase adjustment changes, so that a signal delay unit that changes the delay time according to the frequency of the color sub-carrier is required. But,
In this embodiment, the frequency is temporarily converted to a voltage using the FV converter 55, and the delay time is changed using the voltage control delay line 56 to match the hues of the main screen signal and the sub-screen signal. Then, the main screen and the sub-screen are time-division multiplexed by the analog switch 28, and a picture-in-picture composite video signal is output to the output terminal 31. Switching timing is first
Is controlled based on the synchronization signal separated from the composite video signal of the above, and here, the main screen is L and the sub-screen is H.

In the above embodiment, the voltage control delay line 56 for phase adjustment is inserted on the main signal side, but it may be inserted on the time-compressed sub signal 58 side.

Also, in the above embodiment, one video signal input for the sub-screen has been shown. However, any number may be set. In this case, the sub-screen signal system in the above-described embodiment, that is, the second YC separators 16 at input terminals 15, 2; second sync separator 17, second color signal demodulator 18, first, second, third AD converters 19, 20, 21, first and second , A third digital memory 22, 23,
24, first, second, third DA converters 25, 26, 27, color signal modulator 29, adder 30, first digital processing controller
32 are provided by the number of the sub-screens, and each control signal 48, 49, 51
And the first and second carriers 53 and 54 are common to the sub-signals,
Further, the number of branches of the analog switch 28 may be increased correspondingly.

In the above embodiment, the voltage control delay line 56 for phase matching is inserted on the main signal side, but may be inserted on the time-compressed sub signal 58 side.

Also, in the above embodiment, one video signal input for the sub-screen has been shown. However, any number may be set. In this case, the sub-screen signal system in the above-described embodiment, that is, the second An input terminal 15, a second YC separator 16, a second synchronization separator 17, a second chrominance signal demodulator 18, first, second, and third AD converters 19, 20, 21, and first and second 2, the third digital memory 22, 2
3, 24, the first, second, and third DA converters 25, 26, and 27, the color signal modulator 29, the adder 30, and the first digital processing system controller 32 are provided by the number of the sub-screens. Control signals 48,49,
51 and the first and second carrier waves 53 and 54 may be common to the sub-signals, and the number of branches of the analog switch 28 may be increased accordingly.

〔The invention's effect〕

As described above, according to the video signal synthesizing device according to the present invention, a time axis compression unit that compresses the time axis of a component signal extracted from the first composite video signal inserted into the main screen and serving as a sub-screen, Encoding means for synthesizing a second composite video signal from the component signal whose time axis has been compressed by the time axis compression means, and synchronizing with a color subcarrier of a third composite video signal serving as a main screen, which is used by the encoding means Carrier wave generating means for generating a carrier wave, a frequency-voltage converter for receiving the third composite video signal and outputting a voltage corresponding to the frequency of the color subcarrier, and the third composite video signal for input A voltage-controlled delay line whose delay time is controlled by a voltage output from the frequency-voltage converter, and A delay means for giving a signal delay corresponding to the frequency of the color subcarrier to the third composite video signal, a second composite video signal in synchronization with the third composite video signal, and the delay means A switching means for selectively outputting any of the delayed third composite video signals, wherein the third composite video signal serving as the main screen is modulated and demodulated without being modulated and demodulated. screen,
And time division multiplexing of the sub-screen, so that the phases of the color subcarriers of the main screen and the sub-screen match,
In other words, time-division multiplexing of the main and sub-screens in the state of the composite video signal in a state where the hues match can be performed, and the chroma demodulation and chroma modulation of the main screen are not required. Therefore, a practical effect that it is possible to prevent the deterioration of the image quality of the main screen and to reduce the cost of the entire system can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a video signal synthesizing device according to an embodiment of the present invention, FIG. 2 is a block diagram showing a conventional video signal synthesizing device, and FIG. 3 is a diagram showing a relationship between a main screen and a sub-screen. FIG. 4 is a waveform diagram of each signal derived from the main screen signal in one horizontal period, FIG. 5 is a waveform diagram of each signal derived from the sub-screen signal, and FIG. 6 is a synchronization of the main signal waveform and the sub-signal waveform. 7A and 7B are diagrams illustrating an example of the input / output characteristics of the FV converter and the input / output characteristics of the voltage control delay line, for explaining that the shift amount of the signal timing changes as time passes. 22 to 24 are memories, 29 is a chroma modulation circuit (encoder),
55 is an FV converter, 56 is a voltage control delay line, and 28 is an analog switch circuit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

(57) [Claims] 1. A time axis compression means for compressing a time axis of a component signal extracted from a first composite video signal sent to a main screen and serving as a sub-screen, and wherein the time axis is compressed by the time axis compression means. Encoding means for synthesizing a second composite video signal from the component signal obtained, carrier wave generation means for generating a carrier wave synchronized with a color subcarrier of a third composite video signal serving as a main screen, which is used by the encoding means; A frequency-voltage converter that receives a third composite video signal and outputs a voltage corresponding to the frequency of the color subcarrier; and a voltage that receives the third composite video signal and outputs from the frequency-voltage converter And a signal delay corresponding to the frequency of the color subcarrier of the third composite video signal. To the third composite video signal; and the second composite video signal or the third composite video signal delayed by the delay unit in synchronization with the third composite video signal. Switching means for selectively outputting any one of the main screen and the sub-screen in a composite video signal state without changing or demodulating the third composite video signal serving as the main screen. A video signal synthesizing device. 2. The component signal comprises first and second components, the encoding means for synthesizing the second composite video signal from the first and second component signals, and the delay means. Provides the signal delay to either the third composite video signal or the second composite video signal, and the switching means synchronizes with the composite video signal in FIG. And selecting one of the third composite video signal or the second composite video signal delayed by the delay means and the other composite video signal and outputting the selected composite video signal. 3. The video signal synthesizing device according to claim 1, wherein