JPS63153973A - Video output device - Google Patents

Abstract

PURPOSE:To display a main picture and a sub picture with the same picture quality prominently, by selecting, setting and synthesizing a compressed sub video signal by a signal selection circuit which selects a main video signal. CONSTITUTION:Input video signals from input terminals 1a, 1b,...1n, whose amplitude levels being adjusted at AGC circuits 6a, 6b...6n respectively, are supplied to a signal switching circuit 3, and one of them is set as the main video signal, and others are set as the sub video signals. The main video signal is supplied directly from the circuit 3 to the signal selection circuit 5, and each of the sub video signals, after being compressed at conversion circuits 4b...4n, are supplied to the signal processing circuit 5. The circuit 5 selects the main video signal generally, and when the compressed video signal is supplied from either circuits 4b...4n, it selects the compressed video signal, and performs the set synthesis of the compressed video signal on the main video signal.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention combines two or more types of video signals and creates a sub-screen (child screen) in a part of the main screen (main screen) displayed on a monitor.
The present invention relates to a video output device that can compress and embed images for display.

[Conventional technology]

In recent years, with advances in semiconductor technology, digital signal processing technology using digital memory has been frequently introduced into consumer video equipment. An example of this is a video using a so-called pinP circuit, which combines two types of video signals and compresses and fits a sub-screen into a part of the main screen displayed on the monitor, making it possible to display two screens at the same time. Output devices are known (for example, "Television Technology J September 1984 (Vol. 32) pp.

25-29).

To explain such a video output device with reference to FIG. 3, video signals are input to input terminals 1a and 1b, and these input video signals are respectively supplied to a signal switching circuit 3, where one of these input video signals is selected as the main one. One of the video signals is set as a sub-video signal.

The main video signal is directly supplied from the signal switching circuit 3 to the signal selection circuit 5, and the sub video signal is compressed at a predetermined ratio by the conversion circuit 4 and then supplied to the signal selection circuit 5. The signal selection circuit 5 normally selects the main video signal from the signal switching circuit 3, but when the compressed sub-video signal is supplied from the conversion circuit 4, the video signal for which the supply period is g is selected, The main video signal and the sub video signal are combined. Signal selection circuit 5
The synthesized video signal outputted from the output terminal 2 is supplied to a monitor (not shown), so that a main screen based on the main video signal and a subscreen based on the sub video signal embedded in a part of the main screen are displayed on the monitor. Ru.

Sources of video signals input to the input terminals 1a and lb include television receivers, video cameras, video tape recorders, and image generators. It is possible to simultaneously display screens based on video signals from different sources, such as by inserting and displaying a sub-screen based on reproduced video signals from a video tape recorder on the screen. Of course, if video signals from the same source are simultaneously input to the input terminals 1a and Ib, the main and sub screens will be the same. Also, if the main and sub relationships of the two input video signals are reversed using the signal switching circuit 3,
What used to be the main screen becomes a sub-screen, and the sub-screen becomes the main screen.

[Problem that the invention seeks to solve]

By the way, the amplitude level of the input video signal is not always constant. For example, at present, in a television receiver, a tuner or the like causes a large deviation in amplitude level of 1.0±0.2■ between reception channels. When a deviation occurs in the amplitude level in this way, a visually noticeable difference in contrast occurs between the main screen and the sub screen, which makes the sub screen difficult to see, especially when the main screen is bright and the sub screen is dark. Since the monitor processes the composite signal, if the amplitude level of either or both of the main and sub video signals fluctuates, buzz and overexposure may occur, and contrast may not be obtained on dark screens. Ta.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art and to provide a video output device that can display a main screen and a sub screen in good condition.

[Means for solving problems]

To achieve the above object, the present invention adjusts the amplitude levels of a plurality of input video signals supplied to a means for setting main and sub video signals so that they are equal to each other by an automatic amplitude adjustment circuit. .

[Effect]

The amplitude level of the main video signal and the compressed sub-video signal are equal, and the composite video signal is equivalent to a single video signal generated from a single signal source.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a video output device according to the present invention, in which 1a to 1n are input terminals, 2 is an output terminal, 3 is a signal switching circuit, 4b to 4n are conversion circuits, and 5 is a signal The selection circuits 6a to 6n are automatic amplitude adjustment circuits (hereinafter referred to as A
GC circuit).

In the figure, input terminals 1a, lb,...
- The input video signals inputted from 1n have their amplitude levels adjusted by the AGC circuits 6a, 6b, . . . 6n, respectively, and then are supplied to the signal switching circuit 3, and one of them One is set as the main video signal, and all the others are set as sub video signals. The main video signal is directly supplied from the signal switching circuit 3 to the signal selection circuit 5, and each sub video signal is supplied to the conversion circuits 4b, .
...+4n and then supplied to the signal selection circuit 5. This signal selection circuit 5 normally selects the main video signal, and the conversion circuit 4b...
When a compressed sub-picture signal is supplied from one of the sub-picture signals . The composite video signal output from the signal selection circuit 5 is supplied from the output terminal 2 to a monitor (not shown). As a result, on the monitor, a compressed sub-screen based on the sub-video signal is displayed embedded in a part of the main screen based on the main video signal.

Here, the AGC circuits 6a, 6b, . . . +
6n has the same reference level set and has the same characteristics. For this purpose, input terminals 1a, lb...
...The input video signal input from 1n will be supplied to the signal switching circuit with the same amplitude level, and the main video signal and sub video signal in the composite video signal output from the signal selection circuit 5 will be The amplitude level will be the same. therefore,
The contrast and brightness between the main screen and sub-screen on the monitor are the same, and the main and sub-screens are always easy to see, eliminating buzz, blown-out highlights, and a decrease in contrast on dark screens.
The main and secondary screens can be viewed well.

Note that in FIG. 1, the signal selection circuit 5 is the conversion circuit 4b.
, . . . , only one of the sub-picture signals from 4n may be selected and one sub-screen may be fitted and displayed on the main screen, or multiple sub-picture signals may be displayed. A plurality of sub-screens may be selectively inserted into the main screen. In the latter case, each conversion circuit 4b.

......, sub-picture signals are output from 4n in a predetermined order so that the sub-picture signals do not overlap in time.

FIG. 2 is a block diagram showing the embodiment of FIG. 1 in more detail by taking as an example a video tape recorder, in which 1 is an input terminal, 3a and 3b are changeover switches, 4 is a conversion circuit, 5a and 5b are selector switches, 6 is an AGC circuit,
7 is tuner, 3a.

8b is a changeover switch, 9 is a recording/reproduction processing circuit, 10a,
lQb is a synchronization signal separation circuit, 11 is a demodulation circuit, 12 is a clamp circuit, 13 is A/D (analog/digital)
a conversion circuit, 14 a control circuit, 15 a memory, 16 a D/
A (digital/analog conversion circuit), 17 is a clamp circuit, 18 is an automatic hue adjustment circuit, 19 is an edge generation circuit, and parts corresponding to those in FIG. 1 are given the same reference numerals.

In FIG. 2, an input terminal 1 can be connected to a video camera, another video tape recorder, a television receiver or other image generating device. Furthermore, the demodulation circuit 11, clamp circuit 12, A/D conversion circuit 13, control circuit 14, memory 15, D/A conversion circuit 16, and clamp circuit 17 constitute a conversion circuit 4 that compresses the sub-picture signal.

Next, the operation of this specific example will be described in the case where the screen based on the video signal received by the tuner 7 is used as the main screen, and the screen based on the video signal input to the input terminal 1 is used as the subscreen.

The changeover switches 3a and 8b and the changeover switches 3a and 3b in the signal changeover circuit 3 are closed to the A side, and the changeover switches 5a and 5b in the signal selection circuit 5 are normally closed to the A side.

The input signal received by the tuner 7 is transferred to the selector switch 8a.
After the amplitude level is adjusted by the AGC circuit 6, the signal is supplied as the main video signal to the automatic hue adjustment circuit 18 by the changeover switch 3a in the signal changeover circuit 3. The main video signal whose amplitude of the carrier color signal has been adjusted by the automatic hue adjustment circuit 18 is supplied to the signal selection circuit 5.

On the other hand, the input video signal from the input terminal l passes through the changeover switch 8b and is supplied to the recording/reproduction processing circuit 9. The recording monitor processing system of the recording/reproducing processing circuit 9 is provided with an AGC circuit, and the amplitude level of the supplied video signal is adjusted by this AGC circuit, and the changeover switch 3b of the signal switching circuit 3 is used to convert the supplied video signal into a sub-video signal. is set and supplied to the conversion circuit 4. Here, the AGC circuit 6 and the AGC circuit in the recording/reproduction processing circuit 9 have the same reference level and the same characteristics. As a result, the main video signal and the sub-video signal have the same amplitude level.

In the conversion circuit 4, the sub-picture signal is processed by a demodulation circuit 11 and a clamp circuit 12, respectively, converted into a digital signal by an A/D conversion circuit 13, and written into a memory 15. The control circuit 14 is supplied with a synchronization signal of the output video signal of the recording/reproduction processing circuit 9 obtained by the synchronization signal separation circuit 10b, and controls the operation of the demodulation circuit 11 and the clamp circuit 12 based on this synchronization signal. , A/D conversion circuit 1
Set the sampling frequency of 3 and perform memory write control. Further, the control circuit 14 is supplied with a synchronization signal of the output signal of the AGC circuit 6 obtained by the synchronization signal separation circuit 10a, and based on this synchronization signal, the sub-screen is fitted into a predetermined position on the main screen. The sub-picture signal is read out from the memory 15 at the timing and readout speed. This sub-picture signal is compressed according to the area ratio of the sub-screen to the main screen, and is converted into an analog signal by a D/A conversion circuit 16 controlled by a control circuit 14, and then transferred to a clamp circuit 17.
The signal is clamped to the same reference level as the main video signal from the automatic hue adjustment circuit 18 and supplied to the signal selection circuit 5.

Note that the automatic hue adjustment circuit 18 uses the color burst signals of the main and sub video signals so that the amplitudes of the carrier color signals of these video signals are always equal.

The signal selection circuit 5 is controlled by the control circuit 14 using the synchronization signal from the synchronization signal separation circuit 10a as a reference timing. As mentioned above, the changeover switches 5a and 5b are normally closed to the A side and the main video signal is selected, but the changeover from the main screen to the subscreen during each horizontal scanning period of the main screen into which the subscreen is inserted At the start of fitting, the selector switch 5b is first closed to the B side for a short time to select the edge pulse from the edge generating circuit 19, and then the selector switch 5b is closed to the A side and the selector switch 5a is closed to the B side to compress the pulse. The selected sub-picture signal is selected. At the end of the horizontal scanning period, the changeover switch 5b is closed to the B side to select the edge pulse for a short time, and then the changeover switch 5a is
, 5b are closed to the A side, and the main video signal is selected. Furthermore, during the predetermined number of horizontal scanning periods immediately before the first horizontal scanning period of the main screen into which the sub-screen is fitted and the predetermined number of horizontal scanning periods following the last horizontal scanning period, the fitting period of the horizontal scanning period into which the sub-screen is fitted. Correspondingly, the selector switch 5b is closed to the B side and the edge pulse is selected.

As described above, the signal selection circuit 5 injects and synthesizes the sub-picture signal and the edge pulse into the main video signal, and the resulting composite signal is supplied from the output terminal 2 to a monitor (not shown). As a result, on the monitor, the main screen and the sub-screen fitted into a part of the main screen will be displayed with the same contrast and the same prite, without any buzz or overexposure. , a frame will also be displayed that clearly separates the main screen and sub-screen.

〔Effect of the invention〕

As explained above, according to the present invention, the amplitude level of the main video signal and the sub-picture signal can be reasonably made the same, so that the main screen and the sub-screen can be displayed with the same image quality. This makes each of them very easy to see.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a video output device according to the present invention, FIG. 2 is a block diagram showing an example in which this embodiment is installed in a video tape recorder, and FIG. 3 is a block diagram showing an example of a conventional video output device. FIG. 1a~1n......Video signal input terminal, 2.
......Output terminal, 3...Signal switching circuit, 4b to 4n...Conversion circuit, 5
......K selection circuit, 6a to 6n...
...Automatic amplitude adjustment circuit. Figure 1 Figure 3

Claims (1)

[Claims] 1. A first means for making one of a plurality of input video signals a main video signal and the other as a sub-picture signal, a second means for compressing the sub-picture signal, and a second means for compressing the sub-picture signal; a third means for embedding and synthesizing a sub-video signal, and capable of displaying a sub-screen based on the compressed sub-video signal embedded in a part of the main screen based on the main video signal on a monitor. An automatic amplitude adjustment circuit is provided for each of the input video signals, and the input video signals are adjusted by the automatic amplitude adjustment circuit so that their amplitude levels are equal to each other, and then supplied to the first means. Video output device.