JPH03188782A - Additional signal separation circuit - Google Patents

Abstract

PURPOSE:To increase information quantity to be multiplexed on an overscan area by receiving a color television signal, leading out an output of 1st and 2nd additional signal separation means selectively with a selector means and subtracting a signal obtained from the selector means from a luminance signal. CONSTITUTION:A signal multiplexed with an additional signal is fed to an input terminal 100. Thus, an output of an adder 102 is a sum of upper and lower line signals and color signals whose polarity is inverted between lines are cancelled, only the luminance signal is led out and inputted to a mixture circuit 109 as a signal A. The signal from the input terminal 100 is fed to a field memory 103 and a subtractor 110. Thus, a difference output between fields, that is, the additional signal is separately led out from the subtractor 110. Thus, the luminance signal and the chrominance signal are separated and the additional signal is separated depending on the time band. As a result, the information quantity multiplexed on the overscan area is increased.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention maintains compatibility with an NTSC color television broadcasting system, while also improving the original color television signal in this system. The present invention relates to a system for multiplexing another color television signal onto an original color television signal and transmitting the same, and particularly to an additional signal separation circuit for receiving and demodulating the multiplexed color television signal.

(Prior Art) The NTSC system, which is one of the color television broadcast systems, is compatible with black and white television.

By the way, the image quality of the NTSC system has improved significantly over its long history as a result of constant efforts on both the transmitting side and the receiving side compared to when it was first implemented.

However, in this NTSC system, there is a desire for further improvement in image quality, partly due to the spread of large screen displays in recent years.

IDT as a method to improve the image quality of the NTSC system
V (1mproved Def'1nition T
There is a method called e1evis1on). This method aims to improve the image quality by making full use of the transmitted NTSC color television signal (hereinafter referred to as NTSC signal) on the receiving side.

IDTV was not possible under conventional analog technology, but has become possible due to recent advances in digital technology.

According to IDTV, image quality can be significantly improved compared to conventional analog systems.

However, since IDTV is based on the NTSC system, the upper limit of the image quality that can be improved is limited by the NTSC standard. Here, the upper limit items for the system include: (1) Screen aspect ratio (2) Water 11 resolution 330 TV lines.

The aspect ratio of (1) is currently 4:3, but it is known that users prefer ratios such as 5:3 or B:3 (Broadcasting System published by Japan Broadcasting Publishing Association (Editor) (See page 80 of 2 Japan Broadcasting Corporation)). In addition, high-definition television broadcasting system (lljgh Del'
1njtion Terevislon), 16
:9 aspect ratio may be adopted.

Regarding the horizontal resolution (2), the NTSC system has a horizontal resolution of 4.
Since it is specified as 2 MIIz, the limit is 330 TVs. On the other hand, considering the number of effective scanning lines (480), the vertical resolution is 450
A TV book is possible. Therefore, at this stage, it is desired to improve the horizontal resolution in terms of horizontal and vertical balance.

As an example of a method that improves the above two items and maintains compatibility with current television receivers, for example, Joscp
h L, LoCiccro A compattb+
c HlghD(!flnltion Te1evi
sion System (SLSC) with Ch.
ro m1nancc and Aspect Rat
io Improve SWPTE Jo-urnal,
There is May 1985.

The 5LSC method will be explained below.

Figure 7 shows s1. This shows a television signal spectrum of the SC system. A signal of 0 to 4.2 MHz is a signal to maintain compatibility with current television receivers. The signal of 4.9 to IO, OMHz is an additional signal used for expanding the aspect ratio and the resolution of brightness and chromaticity. Therefore, in the 5LSC system, a signal for one station is transmitted using a band for two channels. One channel basically sends a signal similar to the current television broadcast signal, and the other channel sends an additional signal to improve picture quality.

According to this method, since no additional signals are included in the channels received by current television receivers, it is considered to be highly compatible with respect to interference. However, since each station occupies two channels, it is not efficient as a transmission system. Implementation is expected to be difficult, especially in situations like Japan where channel allocation is near its limit. Furthermore, when considering intra-station and inter-station transmission, current television broadcasting equipment does not have a band that extends to IOMHz, so it is necessary to invest in all new equipment.

From the above, it is desirable to perform transmission within the band of one channel. As a method of newly adding additional information into two channels, a method using a vertical overscan section has been proposed.

Generally, commercially available television receivers are set to overscan. The reason why overscan is set is to provide a margin to prevent screen breakage even if the overall screen position shifts due to changes in deflection amplitude due to fluctuations in high voltage of the receiver.

However, as stability has increased due to improved performance of receivers in recent years, proposals have been made to multiplex additional information into a part of the normally set overscan section of about 8% and transmit it. This proposal was proposed in January 1986, for example.
This is shown in the Technical Report ``Study of Wide Aspect Image Transmission Method'' published by the Television Society of Japan on January 25th.

Since there are 482 effective scanning lines per frame in the vertical direction, 482×8%-38 lines are used for multiplexing new additional information. Therefore, instead of the original television signal, an additional signal is superimposed on each of the 19 upper and lower scanning lines per frame. At this time, normal television receivers have almost no margin due to vertical overscanning. In order to prevent screen dropouts in commercially available television receivers, it is necessary to limit the number of lines to about 7 lines each (14 lines in total), which limits the additional information that can be transmitted.

(Problems to be Solved by the Invention) As described above, in the method of simply multiplexing additional signals in the overscan area, the amount of information is limited. Therefore, a method was proposed in which the additional signals are multiplexed and transmitted by inverting the polarity between fields.

In this way, when extracting the additional signal, it is sufficient to perform subtraction processing between fields, and when erasing it, it is sufficient to perform addition processing between fields.

Therefore, according to this method, there is a possibility that additional signals can be multiplexed and transmitted on each of the 19 lines above and below the conventional overscan area.

However, according to the above proposal, a circuit for additional signal processing is prepared independently on the receiving side (Patent Application No. 1-1-1
No. 44949), which increases the circuit scale on the receiver side.

Furthermore, when additional signals are multiplexed, although it is possible to separate and derive the additional signals in the above system, the additional signals may remain multiplexed with respect to the luminance signal of the main signal, and this may cause interference. may appear on the screen. Considering the overscan of wide aspect television, the effective horizontal scanning period of NTSC is 53.2 μs.
Since the number of vertical effective lines is 482, there is a possibility that the above-mentioned multiplexed position of the additional signal with inverted polarity will appear on the display screen.

Therefore, this invention can increase the amount of information multiplexed in the overscan area, can separate the additional signal with a minimum circuit configuration, and furthermore, the additional signal remains in the main signal and interferes with the screen. It is an object of the present invention to provide an additional signal separation circuit which prevents the occurrence of

[Structure of the Invention] (Means for Solving the Problems) This invention provides a main signal obtained by field repetition in the vertical overscan area of a color television signal, and a main signal obtained by field repetition in which the phase is inverted for each field. In a color television receiver that receives a color television signal multiplexed with the obtained additional signal, and separates the additional signal in a separating means, the separating means receives the color television signal as input and divides the color television signal into one field. a first delay means for delaying the output of the first delay means by one field; and a second delay means for delaying the output of the first delay means by one field; Separating means for separating the luminance signal from the television signal by using the output of the means as the other input; and a first addition for separating the additional signal by using the input and output signals of the first delaying means as two inputs. a signal separating means, a second additional signal separating means for separating an additional signal using input and output signals of the second delay means as two inputs, and selectively outputting the outputs of the first and second additional signal separating means. and subtraction means for subtracting the signal obtained from the selector means from the separated luminance signal.

(Function) The above means can prevent additional signals from remaining in the separated luminance signals. Additionally, the additional signal separation section can be incorporated inside the color/luminance separation circuit.
It is possible to separate additional signals with a large amount of information without increasing the circuit scale.

(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 FIG. 3 shows a circuit configuration, for example, on the transmitting side, which multiplexes an additional signal in an overscan area.

First, the principle of multiplexing additional signals will be explained with reference to FIG.
Thereafter, the additional signal separation means according to the present invention will be explained.

In FIG. 3, 11 is an input terminal to which a main signal is supplied.
3al, l# supplied. The input and output signals of the field memory 12 are added by an adder 14, and then added by a coefficient unit 15.
is multiplied by 1 or 2. As a result, a signal M representing the intra-frame average of the main signal is obtained.

The intra-frame average signal M is applied to the fixed terminal 16 of the switch 16.
a, and is also input to the field memory 17. The signal delayed by one field in the field memory 17 is supplied to the fixed terminal 16b of the switch 16.

The switch 16 selects the output from the coefficient unit 15 in the first field Fl in the frame, selects and derives the output of the field memory 17 in the second field F2, and supplies the output to the adder 23. The adder 23 adds an additional signal A, which will be described later, and the multiplexed signal is supplied to the fixed terminal +3b of the switch 13. switch 13
The selection operation will be described later, but this switch 13 also has a fixed terminal 13c, to which the output from the buffer memory 19 is supplied.

An additional signal A is supplied to the input terminal 18. Additional signal A is input to buffer memory 19. The buffer memory 19 is used to adjust the timing when the additional signal A is multiplexed into the signal M. The additional signal A read out from the buffer memory 19 is supplied to the field memory 21 and the terminal 20a of the switch 20. The additional signal A delayed by one field in the field memory 21 is inverted by the phase inverter 22 and sent to the switch 2.
0 terminal 20b. The switch 20 selects the output from the buffer memory 19 in the first field Fl, selects the output from the phase inverter 22 in the second field F2, and supplies the selected output to the adder 23 described above.

Through the above signal processing and selection processing, the fixed terminal J3a of the switch 3 receives the main 1= signal from the field memory I2,
The fixed terminal 13b is connected to the main (number a) average signal M within the frame.
) and an additional signal whose phase is inverted for each field, a multiplexed signal (M+A) or (M-A) is supplied. Further, the additional signal A from the buffer memory 19 is directly supplied to the fixed terminal 13c.

Next, a control system that controls the operation timing of the signal processing and selection circuit system will be described.

The main signal at the input terminal 11 is supplied to a synchronization signal separation circuit 26 . The horizontal synchronization signal HD and vertical synchronization signal VD separated by the synchronization signal separation circuit 26 are input to the control signal generation circuit 24 and used as reference signals for generating various timing pulses. The control signal generation circuit 24 generates timing pulses for controlling the switches 13, 16, and 20, and also controls the writing and reading timing of input additional signals to the buffer memory 19 via the memory control circuit 25. There is.

As shown in FIGS. 4(A) and 4(B), if the effective scanning line period is represented by an in number minus 1, the first field F
In the field F2, the number is from 22 to 262, as shown by the solid line, and from 285 to 525, as shown by the broken line in the second field F2.

The vertical overscan area is from 22 to 31 on the screen and from 254 to 262 at the bottom of the screen in the first field. Also, in the second field F2, 285~
293, 516-525 at the bottom of the screen.

FIG. 5 shows the first field F1 and the second field F1.
The line number 2 and the selection mode of switch 13 are shown. In FIG. 3, the signal at fixed terminal 13a of switch 13 is assumed to be a main signal, the signal at 13b is assumed to be (M+A) (first field) or (M-A) (second field), and the signal at 13c is assumed to be A, respectively.

On the screen of the first field F1, signal A is selected for lines 22 to 25, and signal (M
+A) is selected, and after line 32, the main (, i) is selected. Also, at the bottom of the screen, the signal (M+A) is selected from lines 254 to 259, and f5 is selected from lines 260 to 262.
No. A is selected.

On the other hand, in the second field F2, signal A is selected for lines 285 to 287 on the screen, signal (M-A) is selected for lines 288 to 293, and
The main signal is selected from line 294 onwards. Further, at the bottom of the screen, signals (M-A) are selected from lines 516 to 521, and signal A is selected from lines 522 to 525.

The timing signal for controlling the switch 13 as described above is generated by the control signal generation circuit 24 counting the synchronization signals.

Now, looking at the relationship between the additional signal A and the intra-frame average signal M in FIG. The inner average signal M and the additional signal A are inserted in association with each other. Also, at the bottom of the screen, additional signal A is directly inserted for line positions 1 to 7, counting from the bottom, and 8 to 7.
The additional signal A and the intra-frame average signal M are inserted in association with each other up to the 19th signal.

Moreover, in the portion where the additional signal A and the intra-frame average signal M are associated, when looking at this from field to field, the polarity of the additional signal A differs as indicated by the arrows in the figure. therefore,
Signal A can be extracted by performing subtraction processing of (M+A) and (M-A) between fields, and signal M can be extracted by performing addition processing.

In other words, the 8th to 19th lines can be viewed as a period in which the main signal and the additional signal overlap.

Fig. 6 shows a receiver installed in a receiver that receives signals processed and transmitted as described above, and normally separates a luminance signal and a chrominance signal. In the overscan region, the circuit is capable of separating and deriving the additional signal.

In FIG. 6, an input terminal 31 is supplied with a 1,5 television signal multiplexed with an additional signal.

The composite television signal is supplied to a line memory 32, an adder 33 to which the output of the line memory 32 is supplied, and is also input to a motion detection circuit 34. The output of the adder 33 is the sum of the upper and lower line signals, and the color signal (carrier color signal) whose polarity is inverted between lines is canceled, and only the luminance signal is derived. This luminance signal is a white signal in the case of a moving image, and becomes one input of the mixing circuit 35. On the other hand, the motion detection circuit 34 obtains the difference between frames and creates a motion detection signal indicating whether the signal at the input terminal 31 is a moving image or a still image. is supplied to the control terminal of The mixing circuit 35 increases the ratio of the signal from the adder 33 when the motion detection signal represents the characteristics of a moving image, and increases the ratio of the signal from the adder 38 (described later) when the motion detection signal represents the characteristics of a still image. The brightness signal is output to the output terminal 51.

Furthermore, the composite television signal at the input terminal 31 is supplied to a field memory 36 and also to a subtracter 39 . The subtracter 39 performs a subtraction process between the output of the field memory 36 delayed by one field and the composite television signal.

As a result, the signal separated and derived by the subtracter 39 is supplied to the fixed terminal β of the switch 40.

The output of the field memory 36 is further input to a field memory 37 which obtains a delayed output for one field.

The output of this field memory 37 is input to an adder 38. The adder 38 performs addition processing between the field memory 37 and the composite television signal. That is, addition processing of signals between signals two fields before (between one frame) is performed. This processing means separation of luminance signals.

That is, in the case of a still image, stable luminance signal separation can be obtained by adding signals between frames.

The output signal of the adder 38 is input to the mixing circuit 35.

Furthermore, the input terminal 31 is connected to the other fixed terminal α of the switch 40. A movable terminal of this switch 40 is connected to a buffer memory 41. The output of the buffer memory 41 is supplied to a color signal and additional signal derivation terminal 52.

A control signal for the switch 40 is output from a control signal generator 43. Further, control signals such as a write clock and a read clock for the buffer 7 memory 41 are as follows.
It is output from a memory control circuit 44 that operates based on a signal from a control signal generator 43. The control signal generator 43 is supplied with the output synchronization signals (horizontal synchronization signal, vertical synchronization signal) of the synchronization signal separation circuit 42 that separates the synchronization signal from the composite television signal, and various controls are performed based on this signal. Generating a signal.

The operation will now be described with reference to FIG.

The switch 40 selects the terminal α at timings corresponding to the first to seventh composite television signals. Then, the additional signal A is taken into the buffer memory 41. Also, at the timing corresponding to the 8th to 19th, the terminal β
Select. Then you will get the calculation output between fields,
The intra-frame average signal M is canceled and the additional signal A is separated and derived.

The above processing is performed in the vertical overscan region. In other main signal areas, switch 4
0 is controlled to select terminal α.

Note that various methods can be considered for using the additional signal. For example, the aspect ratio may be increased, or the resolution of the luminance signal or color signal may be increased.

In the above system, although it is possible to extract the additional signal, there is a possibility that the additional signal is derived while being multiplexed on the main signal side.

For example, the output of the adder 38 is as follows. Especially in the first field 26-31.254-259
, lines 288-293.5 in the second field
16 to 521 (see FIG. 4). In this period, (
M+A)+ (M+A)-2M+2A, (M-A)+
(M-A)-2M-2A is obtained, and the additional signal remains.

This signal would normally be located in the overscan area outside the same-effect screen, so in principle it should not be visible, but it may appear in the six-effect screen due to a synchronization shift or the like.

FIG. 1 shows an improved circuit for obtaining a main signal from which such remaining additional signals are reliably removed.

An input terminal 100 is supplied with a multiplexed signal of additional signals. An input terminal 100 is connected to a line memory 101 and an adder 10 to which the output of this line memory 101 is supplied.
2. Therefore, the output of the adder 102 is the sum of the upper and lower line signals, the color signals whose polarities are inverted between the lines are canceled, and only the luminance signal is derived.
The signal A is input to the mixing circuit 109. This signal A
is an effective signal for moving images.

A motion detection circuit 117 to which the signal of the input terminal 100 is supplied
obtains the difference between frames and creates a motion detection signal indicating whether the signal at the input terminal 100 is a moving image or a still image, and supplies this to the control terminal of the mixing circuit +09. . However, the motion detection circuit 117 outputs a motion detection signal based on the timing signal from the control signal generator 114.

The control signal generator 114 generates various timing signals necessary for the system based on the synchronization signal from the synchronization signal separation circuit 113 to which the signal from the input terminal 100 is supplied.

The signal at the input terminal 100 is further input to the field memory (2
82H delay circuit) 03 is supplied to the subtracter 110.

Therefore, the subtracter 110 outputs the difference between fields,
That is, the additional signal is separated and derived.

The output of the subtracter 110 is supplied to the selector 108 and also to the selector 111. This selector 1
The operation of 08.111 will be further described later.

The output of the field memory 103 is further connected to an IH delay circuit +
Field memory (282H delay circuit) 1 through 04
05. And this field memory 105
The input and output signals of are supplied to a subtracter 107. Therefore, the color signal or additional signal can also be obtained from the subtracter +07. The output signal of this subtracter 107 is supplied to a selector 108.

The output of field memory 105 is also input to adder 106. Adder 106 adds the signal from input terminal 100 and the signal from field memory 105, that is, adds signals between frames. This adder 1
The output signal from 06 is a signal suitable for still images, and is supplied to the mixing circuit 109 as signal B.

Here, the output signal of the adder 10B is further transmitted to the subtracter 11
2 is input. This subtracter 112 is connected to the selector 108
The output signal from the adder 106 is subtracted from the output signal from the adder 106, and the output (a) is supplied as the signal C to the mixing circuit +09.

Buffer memory +15 is a circuit that temporarily stores the output signal from selector I11 and outputs it at a predetermined timing, and is controlled based on a control signal from memory control circuit 118.

Next, the operation of the above system will be explained.

First, the signals input to the input terminal 100 will be classified and explained according to their format. For this reason, the form of the transmitted signal changes depending on the selection state of the switch 13 (shown in Figure 2) on the transmitting side, so when the switch 13 selects the terminal 13a and when the switch 13 selects the terminal 13b. , 13c is selected.

During the period in which the terminal 13a is selected, only the main signal is input to the terminal 100. During this period, the system described above operates as a brightness and color separation circuit, motion is detected by the motion detection circuit 117, and the coefficients of the mixing circuit 109 are controlled.

When the motion detection signal is large, the coefficient of the luminance signal from adder 102 becomes large, and the coefficient of the luminance signal from adder 10B becomes small. Furthermore, when the motion detection signal is small, the coefficient of the luminance signal from the adder 102 becomes small,
The coefficient of the luminance signal from the adder 10G becomes larger.

During the period in which the terminal 13c is selected, only the additional signal is supplied to the input terminal +00. Therefore, the luminance signal output is meaningless.

The selector 111 selects the additional signal (E) and supplies it to the buffer memory 115. Control signal generator +1
4 constantly grasps the form of the signal input to the input terminal +00 in terms of time, and controls the selector l1l108, the memory control circuit 116, and the like.

Period during which terminal 13b is selected During this period, the main signal plus the additional signal (M+A) arrives in the first field, and the main signal minus the additional signal (M-) arrives in the second field. A) will arrive.

Therefore, by obtaining the difference between the fields, the subtractor +
An additional signal (A) can be taken out from 10. Therefore, during this period, the selector 111 receives the input signal (D)
is selected and supplied to the buffer memory 115.

On the other hand, looking at the main signal side during this period, it is as follows. During this period, the mixing circuit 109 first
The output signal A from the subtractor 112 and the output signal C from the subtractor 112 are controlled to be introduced.

When the signal at the input terminal 100 is a moving image, the coefficient of the output luminance signal of the adder 102 becomes large, and the output of the adder +02 is led out to the output terminal 118 via the mixing circuit 109.

On the other hand, for still images, use a subtracter! The ratio of 12 output signals increases.

The signal obtained by the subtracter 112 will be explained.

FIG. 2(a) shows the case where the current signal is the second field, and FIG. 2(b) shows the case where the current signal is the first field. During this period, the selector 108 is controlled to select the output signal G from the subtracter 110 in the first field, and select the output signal F from the subtracter 107 in the second field.

Now, assuming that it is the second field, the main signal M is the luminance component M
When expressed by y and the color component Me, and the additional signal is expressed as A, the following signal is obtained from the adder 10B.

1(My +Mc +A)l+(My -Me +A)
1-2My+2A On the other hand, from the subtractor 110, ((My +Mc +A)l (My+Mc A)
12A is obtained.

As a result, in the subtracter 112, 1(My +Mc +A)l+(My -Me +A)
1t(My +Mc +A)l-(My +Mc -A
)12My is performed, and the remaining additional signal of the main signal is completely removed.

In order to remove the addition (, ? sign), it is necessary to maintain the operation form between the components of the first field and the second field as described above. 2A, the output signal F of the subtracter 107 is selected when the current signal is the second field, and the output signal G of the subtracter 110 is selected when the current signal is the first field.

This control is performed by a control signal generator 114.

As described above, according to this embodiment, in addition to separating luminance and chromaticity, it is possible to separate additional signals according to time periods, and it is also useful for improving image quality without mixing additional signals with luminance signals. be.

[Effects of the Invention] As explained above, according to the present invention, the amount of information multiplexed in the overscan area can be increased, and separation of additional signals can be realized with a minimum circuit configuration. It is possible to prevent the signal from remaining in the main signal and interfering with the screen.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of inter-field calculations shown to explain the operation of the circuit in FIG. 1, and FIG. 3 is an example of an additional signal multiplexing circuit. FIG. 4 is an explanatory diagram of the line configuration of a composite television signal, FIG. 5 is an explanatory diagram of the multiplexing format of the additional signal, and FIG. 6 is an illustration of the additional signal separation circuit that is the premise of this invention. 7 are explanatory diagrams of spectra in the S L SC system. +01...Line memory, +02.10B...Adder, 103.105...Field memory, 104.
...Line memory, 107.110.112...Subtractor, 108.111...Selector, 109...Mixing circuit, 113...Synchronization separation circuit, 114...Control signal generator, 115. ...Buffer memory, 11
G...Memory control circuit, 117...Motion detection circuit.

Claims (1)

[Claims] A main signal obtained by field repetition in a vertical overscan region of a color television signal;
A color television receiver receives a color television signal multiplexed with an additional signal obtained by field repetition in which the phase is inverted for each field, and separates the additional signal in a separating means, the separating means comprising: a first delay means for inputting the color television signal and delaying it by one field; a second delay means for delaying the output of the first delay means by one field; and a second delay means for delaying the output of the first delay means by one field; one input, and the second
a separating means for separating a luminance signal from the television signal by using the output of the delaying means as the other input; and a first separating means for separating the additional signal by using the input and output signals of the first delaying means as two inputs. additional signal separating means; second additional signal separating means for separating additional signals by using input and output signals of the second delay means as two inputs; and outputs of the first and second additional signal separating means. An additional signal separation circuit comprising: selector means for selectively deriving the luminance signal; and subtraction means for subtracting the signal obtained from the selector means from the separated luminance signal.