JPS6047792B2 - 2-screen color television receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-screen television receiver in which a screen of another channel can be inserted into a part of the screen.

FIG. 1 shows a display screen 2 of a two-screen television receiver 1, a sub-screen section 3 whose screen size is reduced in the lower right corner, and a main screen section 4 displayed on the other screen parts other than the sub-screen section 3. This is a front view showing an example.

Insertion of the child screen section 3 into the main screen section 4 is performed as follows. For example, from the video signal of one vertical period before reduction, 3H (
H is one horizontal scanning period), and from the sampled horizontal scanning period, a video signal is extracted every three pixels, for example, to obtain a compressed video signal, and this compressed video signal is is replaced with the video signal of the main screen in accordance with the synchronization signal of the main screen.
/3, balloons a child screen reduced to 1/3 horizontally. Second
The figure is a block diagram of a two-screen television receiver that operates in this manner.

The parent channel unit 10 consists of a main screen selector 11, a video signal detection circuit 12 consisting of an amplification stage and a video detection stage, and a synchronization separation circuit 13, and supplies the main screen video signal and synchronization signal to terminals 1 1 and 102, respectively. do.

The child channel unit 20 also includes a child screen tuner 2L video signal detection circuit 22 and a synchronization separation circuit 23, and receives the video signal and synchronization signal of the child screen from terminals 103 and 23, respectively.
104. The synthesizing unit 30 generates a synthesized video signal to a terminal 105 from the signals supplied to the terminals 101 to 104, which can display an image in which the child screen is reduced and inserted into the main screen, and performs video processing on this synthesized video signal. The image is supplied to a projection section 16 consisting of a circuit 14 and a cathode ray tube 15. The video signal of the small screen supplied to the terminal 103 is digitized by the A/D converter 31 and stored in the buffer memory 32. The buffer memory 32 is a memory that temporarily stores information for one horizontal scanning period. The contents of the buffer memory 32 are sequentially transferred to the main memory (digital one field memory) 33, and the information of one field of the sub-screen is stored in the main memory 33. This signal is read out at a predetermined timing and converted into an analog signal by the D/A converter 34 to obtain a temporally reduced video signal of the small screen. This reduced video signal and the video signal supplied to the terminal 101 are switched by the switching circuit 35 and supplied to the terminal 105. The control circuit 36 supplies the buffer memory 32, the main memory 33, and the switching circuit 35 with a timing signal obtained based on the synchronization signal of the main screen and the synchronization signal of the child screen. Writing to the buffer memory 32 is performed at a predetermined timing based on the child screen synchronization signal, and reading from the main memory 33 is performed at a predetermined timing based on the main screen synchronization signal. Since digital memory cannot be read or written at the same time, information is transferred from the buffer memory 32 to the main memory 33 by selecting a period during which neither writing to the buffer memory 32 nor reading from the main memory 33 occurs. When attempting to realize two screens in a color television receiver, for example, as shown in FIG. It's necessary.

A red difference signal and a synchronization signal for the main screen are supplied to terminals 101A and 102A of the synthesis section 30A, and terminals 103A and 102A are supplied with a red difference signal and a synchronization signal for the main screen.
104A is supplied with a red difference signal and a synchronization signal for the child screen, terminals 101B and 102B of the combining section 30B are supplied with a blue difference signal and a synchronization signal for the main screen, and terminals 103B and 104B are supplied with a synchronization signal for the child screen. A blue difference signal and a synchronization signal are provided for the The compositing units 30A and 30B operate in the same manner as the compositing unit 30, and send red and blue difference signals to terminal 1 that can reduce the child screen and display a color image inserted into the main screen.
Occurs at 05A and 105B. Projection section 16″ is terminal 10
A color image is reproduced from a composite luminance signal generated at terminal 5, a composite red difference signal generated at terminal 105A, and a composite blue difference signal generated at terminal 105B. When trying to convert an analog input signal to, for example, a 6-bit digital signal, it is necessary to compare the input signal with each level obtained by dividing the amplitude of the input signal from the minimum level to the maximum level into 2''.
The circuit scale of the /D converter is extremely large.

Therefore, the combining sections 30 and 3 equipped with the A/D converter 31
A two-screen color television receiver that requires 0A and 30B is expensive. An object of the present invention is to eliminate the need for multiple A/D converters. To provide a two-screen color television receiver capable of reproducing two-screen color images.

The present invention supplies the luminance signal and two color difference signals of the sub-screen to an A/D converter in a predetermined order over one horizontal period, and re-synchronizes the three time-series signals. There is a version that converts the signals into 3D signals and combines them with each signal of the main screen. FIG. 4 is a block diagram showing one embodiment of the present invention.

In FIG. 4, the projection section 16'' is the color image processing circuit 1.
4'' and a color picture tube 15''.

Further, the video signal detection circuits 12'' and 22'' both include a color signal processing stage, and generate red and blue difference signals as well as a luminance signal. The control circuit 36'' of the color composition section 3 is an A/D
Timing signals are supplied to all other blocks in the composite unit 3 except for the converter 31 and the D/A converter 34, but since the diagram becomes complicated, it is difficult to connect the control circuit 36 and the other blocks. The connections between them are not shown.The terminals 106, 107, and 108 of the switch 37 are supplied with the brightness signal, the red difference signal, and the blue difference signal of the sub-screen, respectively. The difference signal is supplied to the A/D converter 31 in a predetermined order, and the A/D converter 31
is converted into a digital signal and generates a luminance signal and a color difference signal. The digitized luminance signal is written into the luminance signal buffer memory 321, and the digitized color difference signal is written into the color difference signal buffer memory 322. The following description will take as an example a case where the child screen is reduced to 1/3.
The signals supplied to the A/D converter 31 are selected as shown in FIG.

In FIG. 5, the periods divided by vertical lines correspond to one horizontal period of the child screen, and the luminance signal, red difference signal, and blue difference signal are selected in the horizontal periods indicated by YlCA and CB, respectively. No signal is selected during the blank horizontal period. The selected signals are written from buffer memories 321 and 322 to main memories 331 and 332, respectively, as shown in FIG. FIG. 6a shows the data storage state of the luminance signal main memory 331, and FIG. 6b shows the data storage state of the color difference signal main memory 332. The selected color difference signal is synchronized with the luminance signals before and after it, and color blurring during reproduction is minimized. For example, the red difference signal CAl is used together with the luminance signals Yl and Y2, and the blue difference signal CB2 is used together with the luminance signals Y2 and Y3. Transfer from the buffer memories 321, 322 to the main memories 331, 332 is performed at the timing shown in FIG. The hatched portion in FIG. 7a is a period for writing to the buffer memories 321, 322, and the hatched portion in FIG. 7b is a period for reading from the main memories 331, 332. From buffer memories 321, 332 to main memories 331, 332
The transfer period must be selected to be a period in which data is neither read from the main memories 331 and 332 nor written to the buffer memories 321 and 322. Main memory 331, 332
There are three types of periods in which reading is not performed from the main memory, *1, *2, and *3 shown in the figure. The latter period 1 does not coincide with the writing period to the brightness signal buffer memory 321. Therefore, at the end of period 1
Data is transferred from the brightness signal buffer memory 321 to the brightness signal main memory 331. Similarly, data transfer of color difference signals is performed during period *2. Furthermore, when using an inexpensive dynamic memory as the main memory, it is necessary to refresh the memory in order to retain information, and the refresh must be performed during a period that does not overlap with writing and reading, but this refresh is performed during the period *
Do it on 3rd.

At the end of the period, the main memories 331 and 332 can be refreshed at the same time, which simplifies the control circuit 36''. through the projection section 16
” is supplied.

A color difference signal used simultaneously with this luminance signal is obtained as follows. As shown in FIG. 6b, the color difference signals stored in the color difference signal main memory 332 cannot be synchronized by simply reading them out, so a permuter used in SECAM color television receivers is used.
This permulator consists of a shift register 38 and switches 391 and 392 that provide a 1H delay. As a result, the outputs of the switches 391 and 392 are as shown in FIG. 8B and c.
A red difference signal CA and a blue difference signal CB are obtained, respectively. Note that FIG. 8a shows a luminance signal Y used simultaneously with the color difference signals shown in FIGS. 8B and 8c. In addition, as mentioned above, the switching circuit 35, the switches 37, 391, 392, the buffer memories 321, 322, the main memories 331, 332,
The operation of the shift register 38 is controlled by a timing signal obtained based on the synchronization signals of the main screen and the child screen.

As described above, according to the present invention, a two-screen color television receiver can be configured by using only one A/D converter 31, thereby reducing the cost of the two-screen color television receiver. be able to.

[Brief explanation of the drawing]

Fig. 1 is a front view showing a television receiver in which two-screen images are reproduced, Fig. 2 is a block diagram of a conventional two-screen television receiver, and Fig. 3 is based on the conventional technology shown in Fig. 2. A block diagram of a possible two-screen color television receiver, FIG. 4 is a block diagram showing an embodiment of the present invention,
Fig. 5 is a time chart showing the order of sub-screen signals supplied to the A/D7 converter, Fig. 6 is a state diagram showing the storage state of the main memory, and Fig. 7 is a write period to the buffer memory and the main FIG. 8 is a time chart showing the reading period from the memory, and FIG. 8 is a time chart showing the relationship between the luminance signal of the sub-screen and the color difference signal. 31...A/D converter, 37...Switch, 38...Shift register, 391,392...
····switch.

Claims (1)

[Claims] 1 An A/D converter that digitizes an analog first television signal, a compression means that temporally compresses the digitized first television signal, and a compressed first television signal that converts the compressed first television signal into analog again. and a synthesizing means for synthesizing this re-analogized first television signal with an analog second television signal. In two-screen television reception that displays images of television signals, at least the first television signal consists of a luminance signal and first and second color difference signals, and the analog luminance signal and the first color difference signal are separated from each other. supplying means for continuously supplying the second color difference signal and the second color difference signal to the same A/D converter in a predetermined order for one horizontal scanning period; A two-screen color television characterized by comprising a synchronizing means for synchronizing a digitized luminance signal, a first color difference signal, and a second color difference signal that appear in time series before being supplied to the combining means. john receiver.