JPH0822080B2 - Video signal synthesizer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a video signal synthesizing apparatus, and in particular, a plurality of composite video signals are simultaneously input, and one of the input composite video signals is used as a main screen, The present invention relates to a device for obtaining a composite composite video signal representing a composite screen inserted into the main screen, with the remaining sub screen serving as a reduced screen.

[Prior Art] FIG. 2 shows a video signal synthesizing device for obtaining a so-called picture-in-picture signal as a composite video signal, that is, a synthetic screen in which another sub-screen is inserted as a reduced screen to a main screen. It is a block circuit diagram showing the prior art example of the apparatus which obtains the represented composite video signal. This conventional example shows the case where there is one sub-screen.

In FIG. 2, (11) is a first input terminal to which a first composite video signal (hereinafter, referred to as “main screen signal”) serving as a main screen (1) is input, and (12) is a first YC. Separator, (13) is a first sync signal separator, (14) is a second input to which a second composite video signal (hereinafter referred to as "sub-screen signal") that is a sub-screen (2) is input The end, (15) is the second YC separator, (1
6) is a chroma (color signal) demodulator, (17) is a second sync signal separator, (18), (19) and (20) are the first, second and third ADs.
Converter (Analog Digital Converter), (21),
(22) and (23) are first, second, and third digital memories that can perform writing and reading at the same time and at mutually asynchronous timing, and (24), (25), and (26) are 1,
The second and third DA converters (digital / analog converters), (27) is the first analog switch, (28) is the chroma modulator, (29) is the YC adder, (30) is the output terminal, ( 3
1) and (32) are the first and second digital signal processing system controllers, and (33) is the first phase-locked loop circuit (hereinafter,
"First PLL circuit"), (34) is the phase detector, (3
5) is a voltage controlled oscillator (hereinafter referred to as "VCO"), (36),
(37) is the first and second carrier signals for chroma modulation generated by the VCO (35), (38) is the second phase locked loop circuit (hereinafter referred to as the "second PLL circuit"), (70) is a reduced sub-screen signal generation circuit, which is a second YC separator (15), a chroma modulator (16), a second sync separator (17), an AD converter (18), (19), ( 20), digital memory (2
1), (22), (23), DA converter (24), (25),
(26), chroma modulator (28), adder (29) and first
Digital processing system controller (31). (39) is a third composite video signal (hereinafter referred to as “reduced sub-screen signal”) representing the reduced sub-screen.

Next, the operation will be described. The main screen signal (1) input from the first input terminal (11) is supplied to the first YC separator (12).
Thereby separates the first color subcarrier signal (40).

On the other hand, the sub-screen signal (2) input from the second input terminal (14) is supplied by the second YC separator (15) to the first luminance signal (41) and the second color sub-carrier signal ( 42). The second color subcarrier signal (42) is demodulated into the first red color difference signal (43) and the first blue color difference signal (44) by the chroma demodulator (16).

First, second and third AD converters (18), (19), (20)
Is a first luminance signal (41), a first red color difference signal (43),
The first blue difference signal (44) is converted into a digital signal, and the first, second, and third digital memories (21), (2
Write in 2) and (23). At this time, the first and second control signals (45) and (46) necessary for write control are generated by the first digital signal processing system controller (31). It is synchronized with the synchronizing signal (47) separated by the signal separator (17), that is, with the sub-screen signal.

Next, the first, second and third digital memories (21),
When reading the contents from (22) and (23), the sub-screen is reduced, that is, compressed in the time direction. The compression in the time direction is performed by reading digital memories (21), (22),
The scanning speed of the contents of (23) is k times (k>
This can be realized by 1), and as a result, 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 (24), (25) and (26). Through this digital signal processing system, the first luminance signal (41), the first red color difference signal (43) and the first blue color difference signal (44) are respectively time-compressed second luminance signal (48). ), A second red color difference signal (49), and a second blue color difference signal (50).

Here, the third and fourth control signals (5
1) and (52) are generated by the second digital signal processing system controller (32).
Is synchronized with the sync signal (53) separated by the sync signal separator (13), that is, the main screen signal (1). Of course,
The obtained second luminance signal (48) and second red difference signal (4
9), the second blue difference signal (50) is also synchronized with this.

The first PLL circuit (33) is a first continuous wave phase-synchronized with the color burst signal contained in the first color subcarrier signal (40) separated by the first YC separator (12). Generate a signal (54). The second PLL circuit (38) has a third color sub-carrier signal (55) generated by the chroma modulator (28).
Second phase-synchronized with color burst signal included in
Generates a continuous wave signal (56). The phase detector (34)
Comparing the phases of the first and second continuous wave signals (54) and (56),
A voltage signal (59) is generated based on the phase difference between the two.
The VCO (35) is controlled by the voltage signal (59) input from the phase detector (34) such that the oscillation frequency and the phase thereof are closer to the first continuous wave signal (54), and they are 90 degrees relative to each other. Continuous first and second carrier signals (36), (3
7) occurs. The first and second carrier signals (36), (3
7) is input to the chroma modulator (28) and time-compressed the second red color difference signal (49) and the second blue color difference signal (5).
0) is modulated into a color subcarrier signal (55). This color subcarrier signal (55) and the time-compressed second luminance signal (4
8) and a fourth composite video signal (hereinafter referred to as “reduced sub-screen signal”) representing a sub-screen that has been reduced by addition by an adder (29).
(39), which is time-division-multiplexed with the main screen signal (1) by the analog switch (27) to form a composite composite video signal (3), which is output from the output end (30).

In the above configuration, the first and second PLL circuits (33) and (38), the phase detector (34), the VCO (35) and the chroma modulator (28)
The signal circuit that circulates through forms a phase locked loop circuit, so that the frequency and phase of the color burst signal contained in the color subcarrier signal (55) modulated by the chroma modulator (28) are , The frequency and the phase of the color burst signal included in the color sub-carrier signal (40) of the main screen signal (1) are automatically adjusted so as to always match.

The analog switch (28) is used for time division multiplexing of the main screen signal (1) and the time-compressed sub screen signal (39).
The switching command signal (58) for the analog switch (27) is synchronized with the main screen signal (1).
In this way, the target composite video signal (3) is obtained at the output end (30).

[Problems to be Solved by the Invention] Since the conventional video signal synthesizing apparatus is configured as described above, the sub-screen synchronization signal and the color sub-carrier signal in the output synthesized screen are subordinate to the main screen. Target. That is, if the main screen is missing, the sub screen will not be output subordinately. This is a problem when editing while monitoring multiple screens at the same time.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a video signal synthesizing device that outputs a sub-screen without any disturbance in the synchronization and hue even when the main-screen signal is lost. To aim.

[Means for Solving Problems] A video signal synthesizing apparatus according to the present invention includes means for detecting a main screen signal loss, and when a loss of the main screen signal is detected, it is generated by a built-in synchronization signal generating circuit. At the same time as switching to the synchronizing signal, the VCO control voltage for generating the carrier signal used for sub-screen modulation is switched so as to be input from a preset power supply.

[Operation] The sync signal detecting means detects the presence or absence of the sync signal included in the main screen signal, and when the sync signal is not detected, the sync signal generating circuit generates the sync signal independently of the main screen signal. The output of is input to the second digital signal processing system controller, and the output control signal of this controller is input to the memory and DA converter of the reduced sub-screen signal creation circuit and time-compressed luminance / red color difference / blue color difference signal. To create. At the same time, the VCO is applied with a preset voltage that is set to a predetermined oscillation frequency, and the VCO is applied to the chroma modulation circuit to which the luminance, red difference, and blue difference signals are input.
To continuously generate the first and second carrier signals output from. Therefore, even if the main screen signal is lost, the reduced sub screen can be continuously monitored.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block circuit diagram of an embodiment of the present invention, and the same reference numerals as those in FIG. 2 represent the same parts.

In FIG. 1, (60) is a sync signal generation circuit that generates a sync signal independently of the main screen signal (1), (61)
Is a sync signal detection circuit that detects a loss of the main screen signal (1) and outputs a loss signal (65), and (62) outputs the output of the synchronization signal generation circuit (60) when the loss signal (65) is received. Second analog switch to input to controller (32), (63)
Is a voltage source that independently generates the set voltage of VCO (35),
When the (64) receives the missing signal (65), it inputs the set voltage of the voltage source (63) to the VCO (35) and sends out the first and second carrier signals (36), (37). It is the third analog switch that is sustained.

 Next, the operation will be described.

The sync signal generation circuit (60) is a circuit that generates a sync signal regardless of the presence or absence of the main screen signal (1). The sync signal detection circuit (61) detects the presence / absence of the sync signal (53) included in the main screen signal (1), that is, the presence / absence of the main screen signal (1), and outputs a missing signal (65) as a binary signal. Is output.
Now, assuming that the main screen signal (1) is missing, the second,
Third analog switch (62). (64) is the missing signal (6
5) is connected from the normal side to the opposite side as shown in the figure, and the sync signal from the sync signal generation circuit (60) to the controller (32) and the output voltage of the VCO set voltage power supply (63) to the VCO ( It automatically switches to input to 35).
Therefore, the sub-screen signal (2) is generated without interruption, so that the sub-screen can be continuously monitored.

In the above embodiment, the combined sub-screen signal (2) is used.
However, the number of sub-screens may be two or more. In this case, the reduced sub-screen signal generating circuits (70) in the embodiment are provided for the number of sub-screens, and the second sub-screen signal generation circuit (70) is provided. PL
An arbitrary one of the reduced sub-screen signals is connected to L (38) as a representative, and each control signal (51), (52), (58) and the first and second carrier waves (36), (37) may be shared by the reduced screen signal generation circuits, and the number of input terminals of the analog switch (27) may be set according to the number of screens.

[Advantages of the Invention] As described above, according to the video signal synthesizing apparatus of the present invention, when the lack of the main screen signal is detected, the synchronizing signal and the VCO set voltage generated internally beforehand are automatically switched. With this configuration, when editing is performed while monitoring a plurality of screens, the sub screen can be continuously monitored even if the main screen signal is lost.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of the present invention, and FIG. 2 is a block circuit diagram of a conventional video signal synthesizer. (27), (62), (63) ... Analog switch, (33),
(38) ... Phase-locked loop circuit, (34) ... Phase detector,
(35) ... Voltage controlled oscillator, (60) ... Synchronous signal generation circuit,
(61) ... Sync signal detection circuit, (63) ... VCO set voltage power supply, (70) ... Reduced sub-screen signal creation circuit. In each drawing, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A composite composite video signal in which a first composite video signal serving as a main screen and a second composite video signal serving as a sub screen are composited and a reduced sub screen is inserted in the main screen. In a video signal synthesizing device to be created, the second composite video signal is separated into a luminance signal, a red color difference signal and a blue color difference signal and time-compressed respectively, and the time-compressed red color difference signal and blue color difference signal are carrier signals. The chrominance subcarrier signal chroma-modulated by
A reduced screen signal generation circuit for generating the composite video signal, a synchronization signal generation circuit for generating a synchronization signal independent of the first composite video signal, and a signal loss detection for detecting the loss of the first composite video signal. Means for maintaining the generation of the carrier wave when the lack is detected and using it as the carrier signal for chroma modulation of the reduced screen signal generating circuit. 2. A first phase-locked loop circuit for generating a first continuous wave signal synchronized with a color burst signal extracted from the first composite video signal, and separated from the first composite video signal. And a controller for receiving a read control signal at the time of time compression and a switching signal of a first analog switch which will be described later, and the second composite video signal into a luminance signal, a red color difference signal and a blue color difference signal. Separated and time-compressed by receiving the read control signal,
And this time compressed red difference signal and blue difference signal
A reduced screen signal generation circuit for generating a third composite video signal by adding the above-time-compressed luminance signal to the chrominance subcarrier signal chroma-modulated by the first and second carrier signals having a phase difference of 90 degrees. A second phase-locked loop circuit for generating a second continuous wave signal synchronized with the color burst signal extracted from the color subcarrier signal created in this circuit;
A phase detector that compares the phases of the second continuous wave signals and outputs a voltage signal corresponding to the phase difference, and a phase detector that is controlled by this voltage signal and is synchronized with the phase of the first continuous wave signal and that is 90 degrees from each other. A voltage-controlled oscillator for generating first and second carrier signals having a phase difference of, and a first composite video signal and a third composite video signal which are switched by a switching signal output from the controller. A time-division multiplexed first analog switch for outputting the composite video signal, a sync signal generating circuit for generating a sync signal independent of the first composite video signal, and an independent control voltage for the voltage controlled oscillator. And a sync signal detection circuit for detecting a loss of the first composite video signal and outputting a drop signal, and a sync signal output from the sync signal generation circuit when the drop signal is received. Above controller To the second analog switch and the control voltage generated by the voltage source to the voltage controlled oscillator when the missing signal is received, and the third analog switch for continuing the generation of the first and second carrier signals. 2. An analog switch, wherein the first and second carrier signals generated by the voltage controlled oscillator are used as a carrier signal for chroma modulation of the reduced screen signal generating circuit according to claim 1. Video signal synthesizer.