JPS63215190A - Synthesizing device for video signal - Google Patents

Abstract

PURPOSE:To prevent the picture quality of a main picture from being deteriorated and to use only one analog switch independently of the number of subpictures by inputting 1st and 2nd carrier signal having a 90 deg. phase difference each other as chrominance signal modulating carrier signals for a contacted subpicture signal forming circuit. CONSTITUTION:The 1st PLL circuit 52 generates a 1st continuous wave signal syncyronizing with a color burst signal included in a chrominance subcarrier signal of a main picture signal and the 2nd PLL circuit 57 generates a 2nd continuous wave signal synchronizing with a color burst signal included in a chrominance subcarrier signal of the contracted subpicture signal. A phase detector 53 outputs a voltage signal corresponding to a phase difference between the 1st and 2nd continuous wave signals. A voltage control oscillator 54 generates the 1st and 2nd carrier signals to be controlled in the direction synchronizing the frequency and phase with the 1st continuous wave signal based on the voltage signal. Thereby, the frequency and phase of the color burst signal are continuously adjusted so as to always coincide with the color burst signal of the chrominance subcarrier of the main screen signal.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a video signal synthesizing device, and in particular, a plurality of composite video signals are input simultaneously, one of the input composite video signals is used as a main screen, The present invention relates to an apparatus for obtaining a composite composite video signal representing a composite screen inserted into the main screen, with the remaining subscreen serving as a reduced screen.

[Prior Art] Fig. 2 shows a video signal synthesis device that obtains a so-called picture-in-picture signal as a composite video signal, that is, a composite screen in which another sub-screen is inserted as a reduced screen into the main screen. 1 is a block circuit diagram showing a conventional example of a device for obtaining a composite video signal. This conventional example shows a case where there is one sub-screen.

In FIG. 2, (11) is the first input terminal into which the first composite video signal (hereinafter referred to as "main screen signal") (1) serving as the main screen is input, and (12) is the first YC signal. Separator, (1
3) is the first chroma (color signal) demodulator, (14) is the first
(15) is the second input terminal into which the second composite video signal (hereinafter referred to as "sub-screen signal") (2) that becomes the sub-screen is input, (IB) is the second YC separator, (
17) is the second chroma (color signal) demodulator, (18) is the second synchronization signal separator, (19), (20), (
21) is the first. Second. Third AD converter (analog-digital converter), (22), (23)
, (24) is the first method that can perform writing and reading simultaneously and with mutually asynchronous timing. Second.
Third digital memory, (25), (2B),
(27) is the first. Second. 3rd DA converter (digital/analog converter), (2B) is an analog switch, (29) is a chroma modulator, (30) is a YC adder, (31) is an output end, (32).

(33) is the first. This is a second digital signal processing system controller.

Next, the operation will be explained. The main screen signal (1) input from the first input terminal (11) is sent to the first YC separator 1.
2) into a first luminance signal (30) and a chrominance subcarrier signal (35) of r51. This first chroma subcarrier signal (35) is separated by a first chroma demodulator (13). The first red difference signal (3B) and the first blue difference signal (
37).

On the other hand, the sub-screen signal (2) input from the second input terminal (15) is converted into a second luminance signal (38) and a second color sub-carrier signal by the second YC divider (1B). (38). The second chroma demodulator (17) converts this second color subcarrier signal (33) into a second red difference signal (
40) and a second blue difference signal (41).

1st. Second. Third AD converter (19)'.

(20) and (21) are the second luminance signal (38)
, second red difference signal (40), second blue difference signal (4
1) into digital signals, respectively. Second.
Third digital memory (22), (23),
(24), at this time, the first . The second control signals (42) and (43) are generated by the first digital signal processing system controller (32), but their timing is determined by the second synchronization signal separator (1).
8) is synchronized with the separated synchronization signal (44), that is, synchronized with the sub-screen signal.

Next, the first. Second. Third digital memory (22)
, (23), and (24), the sub-screen is reduced, that is, compressed in the time direction.

Compression in the time direction is performed when reading from digital memory (
22), (23), and (24) can be realized by making the speed of scanning the contents twice as fast as when writing (k>1),
This results in a digital signal compressed to l/k in the time direction. The digital signal compressed in the time direction is then converted into the first . Second. Third DA converter (25)
, (2B), (27) into an analog signal. After passing through this digital signal processing system, a second luminance signal (38) and a second red color difference signal (40) are output.

The second blue difference signal (41) is a time-compressed third luminance signal (45') and a third red difference signal (4B).
.

It is converted into a third blue color difference signal (47).

Here, the third . Fourth control signal (4
8) and (49) are generated by the second digital signal processing system controller (33), but their timing is synchronized with the synchronization signal (50) separated by the first synchronization signal splitter (14). , that is, it is synchronized with the main screen signal (1). The obtained third luminance signal (45), third
The red difference signal (4B) and the third blue difference signal (47) are also synchronized with this.

The three analog switches (28) are for the main screen signal and
Used for time division multiplexing with time-compressed sub-screen signals,
This analog switch (28) vJ change command signal (5
1) has a timing synchronized with the main screen signal. The result of time division multiplexing by the analog switch (28) is
Since the luminance signal, red difference signal, and blue difference signal are separated, a chroma modulator (28) generates a color subcarrier signal, which is then added to the luminance signal in an adder (30) to obtain the desired signal. A synthesized composite video signal (3) is obtained at the output end (31).

"Problems to be Solved by the Invention" Since the conventional video signal synthesis device is configured as described above, the main screen signal (1) does not require any particular time compression.
It is also necessary to perform demodulation and modulation, which causes deterioration of image quality.In addition, three systems of analog switches are required for time division multiplexing, which increases the number of sub-screens when increasing the number of sub-screens. There were problems such as cost factors.

This invention was made to solve the above-mentioned problems, and it provides a video signal that eliminates the deterioration of the image quality of the main screen, and that allows only one analog switch system regardless of the number of sub-screens, reducing costs. The purpose is to obtain a synthesis device.

Means for Solving Problems L] A video signal synthesis device according to the present invention includes a first PLL circuit that generates a first continuous wave signal synchronized with a color burst signal extracted from a main screen signal; A reduced sub-screen signal generation circuit that time-compresses a signal and creates a reduced sub-screen signal, and a second PL that generates a second continuous wave signal synchronized with a color burst signal extracted from this reduced sub-screen signal.
L circuit and these first. a phase detector that compares the phases of the second continuous wave signal and outputs a voltage signal according to the phase difference; The first one with a phase difference of '. a voltage controlled oscillator that generates a second carrier wave signal; and an analog switch that time-division multiplexes the main screen signal and the reduced screen signal output from the reduced screen creation circuit; The second carrier signal is inputted as a chroma modulation carrier signal to the reduced sub-screen signal generating circuit.

[Operation] The first PLL circuit generates a first continuous wave signal synchronized with the color burst signal included in the color subcarrier signal of the main screen signal, and the second PLL circuit generates a reduced subscreen signal. A second continuous wave signal synchronized with the color burst signal contained in the color subcarrier signal is generated. The phase detector is the first one. A voltage signal corresponding to the phase difference of the second continuous wave signal is output. The voltage controlled oscillator is controlled by this voltage signal so that its frequency and phase are synchronized with the first continuous wave signal. A second carrier signal is generated. Therefore, this first. The frequency and phase of the color burst signal, in which the second carrier signal is included in the color subcarrier of the reduced subscreen signal used for chroma modulation, always match the color burst signal of the color subcarrier signal of the main screen signal. continuously adjusted to Therefore, the main screen signal and the reduced sub-screen signal can be time-division multiplexed using one system of analog switches in the state of a composite video signal, and demodulation and modulation operations are not required for the main screen signal.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, and the same reference numerals as in FIG. 2 represent the same parts. In the figure, (5
2) is a first phase-locked loop circuit (hereinafter referred to as "first PL").
(53) is a phase detector, (54)
is a voltage controlled oscillator (hereinafter referred to as "vco"),
(55), (5B) are the first . the second carrier signal, (
57) is a second phase-locked loop circuit (hereinafter referred to as "second P").
(70) is a reduced sub-screen signal generation circuit, which includes a second YC separator (18), a second chroma demodulator (17), a second sync separator (1st), and an AD Converter (19), (20), (21), Digital memory (22), (23), (24),
DA converter (25), (2El), (2
7), a chroma modulator (29), an adder (30), and a first digital processing system controller (32). (58) is a third composite video signal (hereinafter referred to as "reduced sub-screen signal") representing a reduced sub-screen.

Next, the operation will be explained.

The first PLL circuit (52) includes a first YC separator (
12) first color subcarrier signal (35) separated by
The first phase synchronized with the color burst signal contained in
A continuous wave signal (58) is generated. Second PLL circuit (
57) is the third signal generated by the chroma modulator (29).
The 0 phase detector (53) generates a second continuous wave signal (60) phase-synchronized with the color burst signal included in the color subcarrier signal (61) of the 1° second continuous wave signal. (59) The phases of (eo) are compared and a voltage signal is generated based on the phase difference between the two.

The V CO (54) is controlled so that the oscillation frequency and phase approach the first continuous wave signal (59) by the voltage signal input from the phase detector (53), and
Continuous first . The second carrier signal (
55), generates (5o). This first. The second carrier signal (55), (513) is transmitted through a chroma modulator (
29) and the time-compressed third red difference signal (
4B) and the third blue difference signal (47) are modulated onto a color subcarrier signal (61). This color subcarrier signal (61)
and the time-compressed third luminance signal are sent to an adder (30).
A fourth composite video signal representing the reduced sub-screen (hereinafter referred to as "reduced sub-screen signal") is obtained by adding the signal to the main screen signal (1), and is time-division multiplexed with the main screen signal (1) by the analog switch (28) to produce a composite composite signal. It becomes a video signal and is output from the output terminal (31).

Among the above configurations, 1. Second PLL circuit (52).

(57), the phase detector (53), the VCO (54), and the signal circuit circulating through the o-y modulator (28) form one phase-locked loop circuit, and therefore the chroma modulator (28) modulated color subcarrier signal (6
The frequency and phase of the color burst signal included in 1) are the same as the frequency and phase of the color burst signal included in the color subcarrier signal (35) of the main screen signal (1).
Automatic adjustment is made to always match.

Therefore, the main screen signal (1) and the reduced sub-screen signal (58
), the frequency and phase of the color subcarrier signal match, so the hue of the composite screen is automatically matched.

In the above embodiment, the number of sub-screen signals (2) to be synthesized is one, but the number of sub-screens may be two or more, and in this case, the reduced sub-screen signal generation circuit in the embodiment (70) are provided for the number of sub-screens, and the second PL
Any one of the reduced sub-screen signals is connected to the L circuit (57) as a representative, and each control signal (48), (49)
, (51) and 1st. second carrier wave (55),
(5B) may be made common to each reduced sub-screen signal generation circuit, and the number of input terminals of the analog switch (28) may be made in accordance with the number of screens.

[Effects of the Invention] As described above, according to the video signal synthesis device according to the present invention, the first continuous wave signal synchronized with the color burst signal included in the color subcarrier signal of the main screen signal is PLL
On the other hand, a second continuous wave signal synchronized with the color burst signal included in the color subcarrier signal generated by the reduced subscreen signal generation circuit is generated using a second PLL circuit. Let these first. phase detecting the second continuous wave signal, controlling a voltage controlled oscillator with the output voltage signal to have a phase difference of 90° from each other;

The first one synchronized with the color burst signal of the brush screen signal.
A second carrier wave signal is generated, and this first and second carrier wave signals are used as carrier wave signals for chroma modulation in the reduced sub-screen signal generation circuit, and the main screen signal and the time-compressed reduced screen signal are generated using an analog switch. Since it is configured to perform time division multiplexing, the main screen signal is not demodulated or modulated, so there is no deterioration in image quality, and moreover, the hues of the main screen and sub screen are automatically matched. Furthermore, since time-division multiplexing is performed in the state of a composite video signal, multiplexing can be performed with one system of analog switches regardless of the number of sub-screens, so there is an effect that a high-quality and inexpensive video signal synthesis device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing an example of a video signal synthesis device according to the present invention, and FIG. 2 is a block circuit diagram of a conventional video signal synthesis device. (28)...Analog switch, (52), (5
7)... Phase locked loop circuit, (53)... Phase detector, (54)... Voltage controlled oscillator, (70)...
- Reduced sub-screen signal creation circuit. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A first composite video signal serving as the main screen and a second composite video signal serving as the subscreen are combined to create a composite composite video signal in which a reduced subscreen is inserted within the main screen. The video signal synthesis device includes: a first phase-locked loop circuit that generates a first continuous wave signal synchronized with a color burst signal extracted from the first composite video signal; A luminance signal, a red difference signal, and a blue difference signal are separated and time-compressed, and the time-compressed red difference signal and blue difference signal are chromagraphed using first and second carrier signals having a phase difference of 90 degrees. A reduced screen signal creation circuit that adds the time-compressed luminance signal to the modulated color subcarrier signal to create a third composite video signal, and a color burst extracted from the color subcarrier signal created within this circuit. A second phase-locked loop circuit that generates a second continuous wave signal synchronized with the signal and compares the phases of the first and second continuous wave signals and outputs a voltage signal according to the phase difference. a phase detector, a voltage controlled oscillator that is controlled by the voltage signal and generates first and second carrier signals that are synchronized with the phase of the first continuous wave signal and have a phase difference of 90° from each other; an analog switch that time-division multiplexes the first composite video signal and the third composite video signal and outputs the composite composite video signal; A video signal synthesis device configured to be used as first and second carrier wave signals for chroma modulation in the reduced screen creation circuit. (2) A plurality of reduced screen signal generation circuits into which the first and second carrier signals are respectively input as carrier wave signals for chroma modulation, and a plurality of third composite signals outputted from these reduced subscreen signal generation circuits. an analog switch for time-division multiplexing the video signal and the first composite video signal; 2. The video signal synthesis device according to claim 1, wherein the video signal synthesis device is configured to generate the second continuous wave signal by inputting the signal into a synchronous loop.