JPH01164187A - Plural-screen processor - Google Patents

Abstract

PURPOSE:To obtain a stable reproduced picture by using only the luminance signal as the video signal for the child screen, superimposing the sine wave of a frequency in a chrominance signal band on the luminance signal and supplying the superimposed luminance signal to a switching means when a video signal for a parent screen is a SECAM system and another video signal for a divided picture is a PAL system. CONSTITUTION:A luminance compensating circuit 500 is equipped with a discriminating circuit 41 to discriminate whether a first video signal to display the parent screen is the PAL system or the SECAM system, a switch 43 controlled by the discriminated result of the discriminating circuit 41, and an oscillator 42 obtain the oscillation output within a chroma frequency band. When the first video signal is the PAL system, the switch 43 selects a chrominance signal from an encoder 29 and supplies the signal to a mixing circuit 30, and when the first video signal is the SECAM system, the switch 43 selects the output of the oscillator 42 and supplies the output to the mixing circuit 30. Thus, the scale of the circuit and the price of the title device are not increased, and the stable reproduced picture can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a multi-screen processing device that simultaneously displays color video signals of different formats on the same screen.

(Prior Art) Recently, television receivers have been developed that can display a plurality of screens simultaneously on the same screen.

For example, while the screen of a certain channel (hereinafter referred to as the main screen) is being displayed, the screen of another channel (hereinafter referred to as the child screen) is displayed in a reduced form on the right, bottom, or bottom left. This type of television receiver is equipped with a signal processing circuit for the main screen and a signal processing circuit for the sub-screen, and the video signals for the main screen and sub-screen from these two circuits are switched by switching means and are continuous. In this way, a third video signal for multiple screens is created.

FIG. 2 shows a conventional multiple screen processing circuit.

The first video signal is supplied to the input terminal 11 of the main screen signal processing circuit 100. The video signal at the input terminal 11 is supplied to one input terminal of the switch means 300, and is also supplied to the bandpass filter 12 and the sync separation circuit 14. Bandpass filter 12 extracts a chroma band signal and supplies it to decoder 13 . The decoder 13 is
Color synchronization information is generated and supplied to an encoder 29 of a sub-screen signal processing circuit 200, which will be described later, to synchronize the sub-screen color signal with the main screen color signal.

The vertical and horizontal synchronization signals separated by the synchronization separation circuit 14 are sent to a picture-in-picture (hereinafter referred to as PIF) control circuit 40 that controls the operation timing of each part of this system.
Supply to 0.

A second video signal is supplied to input terminal 21. Second
The video signal of sync separation circuit 22. Bandpass filter 23
．． A low pass filter 24 is provided.

The color signal extracted by the bandpass filter 23 is sent to a decoder 25
The color difference signals are converted into color difference signals (R-Y) and (B-Y), and then supplied to the analog-to-digital converter 26. Furthermore, the luminance signal extracted by the low-pass filter 24 is also supplied to the analog-to-digital converter 26 . Analog-digital converter 2
The sampling clock at step 6 is given from the PIF control circuit 400 described above. The digital signal quantized by the analog-to-digital converter 26 is stored in the memory 27. The write speed of the memory 27 corresponds to the speed at which the second video signal was sampled and is synchronized with the second video signal. A write clock is also provided from the PIF control circuit 400.

The digital signal h1 read out from the memory 27 is converted into an analog color difference signal (R-
Y), (B-Y), which is reproduced as a luminance signal Y. In this case, the read clock provided from PIF control circuit 400 is synchronized with the first video signal and is fast. Therefore, the color difference signals (R-Y) and (B-Y) are decoded to reproduce the color signal, and the luminance signal Y is added to the color signal by the adder 30.
The small screen video signal obtained by adding the second video signal is a reduced version of the second video signal.

The small screen video signal obtained in this way is supplied to the other terminal of the switch means 300. Switch means 30
0 is controlled by a timing pulse from the PIP control circuit 400, and selects the video signal for the child screen at the timing of inserting the child screen, and selects the video signal for the main screen during other periods and outputs it to the output terminal 31. do. This allows terminal 3
1, a third video signal is obtained that displays multiple screens simultaneously on the same screen. In this case, synchronization of the color signals between the child screen video signal and the main screen video signal is achieved by injecting color synchronization information from the main screen signal processing circuit 100 into the encoder 29. There is. In other words, the carrier generating section of the encoder 29 is phase-synchronized with the burst on the main screen side.

(Problems to be Solved by the Invention) In Europe, the PAL system is the mainstream color television system, and there is a demand for a PIF system that can process PAL signals. However, in some regions, both PAL and SECM systems can be received, so a PIF system that can process video signals of a plurality of different systems is required.

Therefore, when considering a system that can handle input video signals of different formats, the following configuration can be considered.

■Decoder and encoder for FAI and system respectively,
Prepare separately for the SECAM method. A circuit for determining the format of a video signal serving as a main screen and a video signal serving as a sub-screen is provided. Next, based on the result of the discrimination by the discrimination circuit, the switching means selects and switches the encoder and decoder that process the signal.

- With this configuration, color reproduction can be obtained even if the PAL system is the main screen or the child screen and the SECAM system signal is the child or main screen. However, since it requires two sets of encoders and decoders, a circuit for determining the system, and a switching means, the circuit size becomes large, and the circuit becomes complicated and expensive.

(2) A configuration different from the above is configured so that only the luminance signal is processed as the signal that becomes the child screen. With this configuration, if the main screen signal is of the PAL system, the child screen has only a luminance signal, and therefore becomes a black and white screen.

However, if the signal for the main screen is in the SECAM format and the signal for the sub-screen is only a luminance signal component, the sub-screen will appear as random color noise on the display screen of the receiver.
The image quality deteriorates significantly and the product value is lost. That is, the receiver side determines that the third video signal is of the SECAM system, and performs demodulation adapted to this system. However, S
In the ECAM system, even if it is monochrome, normal demodulation is obtained by superimposing an unmodulated carrier on the luminance signal and transmitting it, but in the above sub-screen, only the luminance signal is used, and the color image is undefined. It is from.

■The PIF system is compatible only with the FAI method.

With this configuration, if the main screen signal is in the PAL system and the child screen signal is in the SECAM system, the child screen will be a black and white image. However, if the main screen signal is in the SECAM system and the child screen signal is in the PAL system, the color synchronization information of the main screen's color signal cannot be detected, so the colors of the child screen will be random. Further, if the signal of the main screen is of the SECAM system and the signal of the child screen is also of the SECAM system, the child screen becomes a random color noise image with only a luminance signal, as in the case (2).

■SECAMSECAM method F system. With this configuration, if the sub screen signal is PAL format,
The color signal of the sub screen becomes random and the sub screen becomes a noise image. Furthermore, if the main screen signal is in the PAL format and the sub-screen signal is in the SECAM format, color synchronization (DR) is used to encode the sub-screen signal.

DB array) cannot be obtained, the child screen will have an abnormal color.

As explained above, the configuration (2) increases the circuit scale and the cost. Configuration (2) simplifies the circuit, but basically cannot reproduce colors. Furthermore, the main screen is SECA
If it is an M system signal, the sub screen will be a random color noise image. In the configuration (2), when the main screen is a signal of the SECAM system, the child screen becomes a random color noise image or a color abnormal placement surface. The configuration (2) not only does not support the mainstream PAL system, but also makes the sub-screen a noise image. Arani PAL/
There is no flexibility in making it compatible with the SECAM system.

As mentioned above, conventional signal processing circuits are PAL/NT
If an attempt is made to change to a PIF system compatible with the SC method, there are problems such as an increase in circuit scale, an increase in price, and a decrease in functionality.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multi-screen processing device that does not require an increase in circuit scale or increase in cost, and can provide stable reproduction.

[Structure of the Invention (Means for Solving the Problems)] The present invention provides a first video signal processing circuit to which a first video signal is supplied and which obtains a main screen video signal, and a second video signal. a second video signal processing circuit that is supplied with a video signal for a small screen and obtains a video signal for a sub-screen; a switch means for selectively deriving the output video signal of the second video signal processing circuit to obtain a third video signal forming a plurality of screens on one screen; ml video signal is a SECAM system color video signal No. 15, and the second video signal is a PAL system color video signal, only the brightness signal is used as the video signal for the small screen, and the brightness in parentheses is The signal is configured to be superimposed with a sine wave having a frequency within the color signal band and supplied to the switch means.

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

FIG. 1 shows an embodiment of the present invention, and the difference from the circuit in FIG. 2 is a brightness compensation circuit 500 surrounded by a dashed line. Since the other parts are the same as the circuit explained in FIG. 2, the same reference numerals as in FIG. 2 are given.

The brightness compensation circuit 500 includes a discrimination circuit 41 that discriminates whether the first video signal representing the main screen is FAI or SECAM, and a switch 43 that is controlled by the discrimination result of the discrimination circuit 41. and an oscillator 42 that obtains an oscillation output within the chroma frequency band.

If the first video signal is PAL, the switch 43 selects the color signal from the encoder 29 and sends it to the mixing circuit 3.
0, and if the first video signal is of the SIECAM format, the output of the oscillator 42 is selected and supplied to the mixing circuit 43.

A: If the signal of the main screen is PAL format al: If the signal of the slave screen is PAL format, the slave screen is displayed as a color image.

a2: If the sub-screen is in the SECAM format, the sub-screen will only be a luminance signal, and in a receiver operating in the PAL processing mode, the sub-screen will be displayed as a monochrome image,
No color noise.

B: When the main screen signal is in the SECAM system bll When the child screen signal is in the PAL system, the color synchronization information of the main screen signal cannot be obtained in the decoder 29, so the color signal of the child screen is converted into the regular PAL system color signal. cannot be encoded as . If this is superimposed on the brightness signal as a color signal for the child screen, the child screen will have random colors. Therefore, in this case, the color signal is cut by the switch 43, and instead, the unmodulated carrier from the oscillator 42 is superimposed on the luminance signal of the sub-screen. As a result, even if the receiver operates in SECAM mode, random noise will not appear on the sub screen.

Even when the b22,000 double-sided signal is of the SIECAM system, random noise does not appear on the child screen, as described above.

[Effects of the Invention] As described above, the present invention can provide a multi-screen processing device that does not increase the circuit scale or increase the price and can provide stable reproduction.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional multiple screen processing circuit. 12.23...Band filter, 13.25...Decoder, 14.22...Synchronization separation circuit, 26...Analog-to-digital conversion section, 27...Memory, 28...Digital-to-analog conversion section , 29... encoder, 30...
... Mixing circuit, 41... PAL/SHCAM discrimination circuit, 42... Oscillator, 100... Signal processing circuit for main screen, 200... Signal processing circuit for sub-screen, 300...
switch means, 400... picture-in-picture control circuit, 500... brightness compensation circuit; Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Scope of Claims] A first video signal processing circuit that is supplied with a first video signal and obtains a video signal for a main screen, and a second video signal that is supplied with a second video signal and obtains a video signal for a sub-screen. A processing circuit, and a switch means for selectively deriving the output video signal signals of the first and second video signal processing circuits to obtain a third video signal forming a plurality of screens on one screen. In the multi-screen processing device, when the first video signal is a SECAM color video signal and the second video signal is a PAL color video signal, the sub-screen video signal is a luminance signal thereof. 1. A multi-screen processing device characterized by comprising means for superimposing a sine wave having a frequency within a color signal band on the luminance signal and supplying the same to the switch means.