JPS62276972A - Video signal synthesizer - Google Patents

Abstract

PURPOSE:To prevent deterioration in picture quality due to demodulation and modulation by applying time-division multiplex to subpicture in the state of a composite video signal without applying demodulation/modulation with respect to a main picture. CONSTITUTION:Continuous carrier waves 53, 54 having equal frequency to a color burst signal of a main signal and having a phase difference of 90 deg. are obtained by a PLL 52 so that the frequency and the reference phase of the chrominance subcarrier of the main signal and the chrominance subcarrier of a sub signal 58 subjected to re-modulation after time compression are equal to each other. A conversion voltage 57 in response to the frequency of the carrier 53 or 54 is generated from an FV converter 55 and the conversion voltage 57 controls a voltage-controlled delay line 56 inserted at the main signal side. Further, the frequency and the reference phase of the chrominance subcarrier of the main signal and the sub-signal 58 at the input terminal of an analog switch 28 are matched automatically. Then a switch 28 applies the time-division multiplex to the main picture and the sub-picture and a composite video signal of picture-in-picture is outputted at an output terminal 31.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a video signal synthesis device, and in particular, the present invention relates to a video signal synthesis device, in which a plurality of composite video signals are simultaneously input, and one of the manually generated composite video signals is The present invention relates to a device for obtaining a composite video signal in which one screen is used as a main screen and the remaining screens are used as sub-screens, and the sub-screens serve as reduced screens and represent a composite screen inserted into the main screen.

[Conventional technology]

Figure 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 as described above. 1 is a block diagram showing a conventional example of a device for obtaining a composite video signal; FIG.

This conventional example shows a case where there is one sub-screen.

In FIG. 2, 11 is a first input terminal into which the first composite video signal serving as the main screen is input, 12 is a first YC separator, 13 is a first chroma (color signal) demodulator, and 14 1 is a first synchronization signal separator, 15 is a second input terminal into which a second composite video signal serving as a sub-screen is input, 16 is a second YC separator, and 17 is a second chroma (color signal). demodulator, 18 is a second synchronizing signal separator, 19, 20, 21 is a first . Second. Third
AD converter (analog-digital converter), 2
2.23.24 is the first type that can write and read simultaneously and with mutually asynchronous timing. Second.
The third digital memory, 25°26.27, is the first. Second. 3rd 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 end, 32.3
3 is a first and second digital signal processing system controller.

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

On the other hand, the second composite video signal input from the second input terminal 15 is converted into a second luminance signal 38 by the second YC separator 16.
and a second color subcarrier signal 39. This second color subcarrier signal 39 is converted into a second red difference signal 40 and a second blue difference signal 41 by second color signal demodulation 2i1.
is demodulated.

1st. Second. The third AD converter 19,20°21 converts the second luminance signal 38. The second red difference signal 40 and the second blue difference signal 41 are each converted into digital signals, and the first . Second. Write to the third digital memory 22, 23, 24. At this time, the first . Second
The control signals 42 and 43 are generated by the first digital signal processing system controller 32, but their timing is synchronized with the synchronization signal 44 separated by the second synchronization signal separator 8, that is, the second is synchronized with the composite video signal of

1st. Second. Third digital memory 22, 23, 24
When reading the contents from the sub-screen, the sub-screen is reduced, that is, compressed in the time direction. Compression in the time direction can be achieved by increasing the speed at which the contents of the digital memory are scanned when reading out to twice the speed at which it is written (k>1), resulting in a digital signal compressed to 1/k in the time direction. . This digital signal compressed in the time direction is the first. Second. It is converted into an analog signal by a third DA converter. After passing through the digital signal processing system, the second luminance 18;
No. 38. Second red difference signal 40. Second blue difference signal 41
are respectively the time-compressed third luminance signals 45. Third red difference signal 46. It is converted into a third blue color difference signal 47.

Here, the third . Fourth control signal 48
．． 49 is a second digital signal processing system controller 33
These timings are synchronized with the synchronization signal 50 separated by the first synchronization signal separator 14, 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. The third blue color difference signal 47 is also synchronized with this.

The analog switch 28 is used for time division multiplexing of the main screen and the time-compressed sub-screen.
The switching command signal 51 is a timing synchronized with the main screen. Since the result of time division multiplexing by the analog switch 28 is separated into a luminance signal, a red difference signal, and a blue difference signal, a color subcarrier is generated in the color signal demodulation 2S29, and then a luminance signal is generated in the adder 30. The target composite video signal is obtained at the output terminal 31 by adding the above.

[Problem that the invention seeks to solve]

Since the conventional video signal synthesis device is configured as described above, it is necessary to perform demodulation and modulation even for the main screen that does not require time compression, which causes deterioration of image quality. Three systems of analog switches are required for time division multiplexing, which has the drawback of becoming a major cost factor when the number of sub-screens is increased.

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

[Means for solving problems]

The video signal synthesis device according to the present invention uses a PLL to generate a carrier wave synchronized with a color burst signal included in a composite video signal of a main screen, and generates a carrier wave synchronized with a color burst signal included in a composite video signal of a main screen. This is a carrier wave, and after modulation, it is configured to be time-division multiplexed using a single analog switch.

[Effect]

In this invention, since the PLL provides a carrier wave when remodulating the sub-screen in synchronization with the color burst signal of the main screen, it is possible to time-division multiplex the main and sub-screens in the state of a composite video signal. Moreover, demodulation and modulation of the main screen is not necessary.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a video signal synthesis device according to an embodiment of the present invention,
In the figure, the same reference numerals as in FIG. 2 represent the same parts.

In Fig. 1, 52 is PLL, 53.54 is MlP
The first .L for chroma modulation generated by L L 52. The second carrier wave, 55 is a frequency-voltage converter (hereinafter referred to as FV converter), and 56 is a voltage-controlled delay line.

Next, the operation will be explained.

In order to make the color subcarrier of the main signal and the color subcarrier of the time-compressed and page-modulated subsignal 58 equal in frequency and reference phase, first, the PLL 52 is used to make the color subcarrier of the main signal equal in frequency and mutual with the color burst signal of the main signal. Continuous first . A second carrier wave 53,54 is obtained. Next, a converted voltage 57 corresponding to the frequency of the carrier wave 53 or 54 generated by this PLL 52 is generated by the FV converter 55, and the voltage controlled delay line 56 inserted on the main signal side is controlled by the converted voltage 57,
The frequencies and reference phases of the color subcarriers of the main signal and the subsignal 58 at the input end of the analog switch 28 are automatically matched. Then, the main screen and the sub screen are time-division multiplexed using the analog switch 2, and a picture-in-picture composite video signal is output to the output terminal 31.

In the above embodiment, the voltage-controlled delay line 5G for phase matching is inserted on the main signal side, but it may be inserted on the time-compressed sub-signal 58 side.

Further, in the above embodiment, the number of video signal inputs for the sub-screen is one, but it may be set to any number. In this case, the sub-screen signal input in the above embodiment, that is,
second input terminal 15, 20th) YC separator I6, second sync separator 17, second color signal demodulator 18, first . Second.
The third AD converter 19, 20, 21, the first . Second.
The third digital memory 22, 23.24, the first . Second
゜ Third DA converters 25, 26, 27, color signal modulators 29, adders 30, and first digital processing system controllers 32 are provided for the number of sub-screens concerned, and each control signal 4
8, 49.51 and 1st. The second carrier waves 53 and 54 may be made common to each sub-signal, and the number of branches of the analog switch 28 may be increased accordingly.

〔Effect of the invention〕

As described above, the video signal synthesis device according to the present invention is configured to perform time-division multiplexing with the sub-screen in the composite video signal state without demodulating or modulating the main screen. It eliminates the need for a demodulator for the screen, prevents deterioration in image quality due to demodulation and modulation, and requires only one system of analog switches regardless of the number of sub-screens, making it possible to configure the device with high image quality and at low cost. It has great practical effects.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a video signal synthesis device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional video signal synthesis device. 22 to 24 are memories, 29 is a chroma modulation circuit (encoder), 55 is an FV converter, 56 is a voltage controlled delay line,
28 is an analog switch circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A video signal in which a first composite video signal representing a main screen and a second composite video signal representing a sub-screen are input, and a signal representing a composite screen in which a reduced sub-screen is inserted within the main screen is created. A synthesizing device comprising: a memory for storing first and second component signals constituting a second composite video signal; and a synthesizer configured to reduce the size of the first and second component signals read from the memory at a faster speed than when they are written. an encoder that generates a third composite video signal representing a sub-screen; and an encoder that is phase-synchronized with the color subcarrier of the first composite video signal.
a phase-locked loop that generates a carrier signal for modulation in the encoder; a frequency-voltage converter that outputs a converted voltage according to the frequency of the color subcarrier of the first composite video signal; and a delay time according to the converted voltage. a voltage-controlled delay line that delays either the first or third composite video signal by changing the voltage; and one of the voltage-controlled delay lines delays the first and third composite video signals delayed by the voltage-controlled delay line. A video signal synthesis device comprising: an analog switch circuit that switches and outputs a first composite video signal in synchronization with the first composite video signal.