JPH07298220A - Broadcast signal identification circuit and television receiver using it - Google Patents

Abstract

PURPOSE:To allow the identification circuit to identify whether a broadcast signal is an NTSC signal or a 2nd generation EDTV system signal by receiving a broadcast signal for a period when an identification code of the NRZ form is inserted with a fetch means and allowing an identification means to identify it that the broadcast signal fetched by the fetch means is the NRZ form identification code. CONSTITUTION:A composite video signal received via an input terminal 1 is fed to a comparator 2, in which the signal is compared with reference value and the video signal is waveform-shaped to be an 'L' level or an 'H' level. The output of the comparator 2 is fed to a data processing circuit 3. The data processing circuit 3 receives a timing pulse representing a timing of bit areas B1-B5 of an identification signal to extract each signal for 5 periods being bit areas B1-B5 of 22nd H and 285th H based on the timing pulse. The data processing circuit 3 identifies whether received signal is an NTSC system signal or a letter box system signal of the 2nd generation EDTV system.

Description

Detailed Description of the Invention

[Object of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broadcast signal identifying circuit compatible with the second generation EDTV system and a television receiver using the same.

[0002]

2. Description of the Related Art In recent years, second-generation EDTV broadcasting aimed at high image quality and high sound quality has been studied. Second generation E
DTV broadcasting has compatibility with the current broadcasting, and the aspect ratio of the screen is set to 16: 9 horizontally so that it is possible to watch programs with a sense of realism. At the beginning of broadcasting, it is expected that a current NTSC system signal having an aspect ratio of 4: 3 and a second generation EDTV system signal having an aspect ratio of 16: 9 will be mixed and broadcast for each program.
Therefore, it is necessary for the receiving side to perform control corresponding to the current NTSC system and the second-generation EDTV system, respectively.

The effective scanning line of the second generation EDTV signal corresponds to the 16: 9 portion in the vertical center of the current NTSC signal having an aspect ratio of 4: 3. Therefore, for example, when the second-generation EDTV broadcast is displayed by a television receiver for current broadcasting having an aspect ratio of 4: 3, letterbox display having a non-image part at the top and bottom of the screen is performed. The non-image portion is, for example, a black level signal.

However, flicker and screen noise may occur in the non-image area due to the influence of an interfering signal or noise. Then, the display of the non-image portion becomes unpleasant, and it becomes difficult to see the image in the effective scanning period.

On the other hand, it is conceivable to receive a second generation EDTV signal by a television receiver having an aspect ratio of 16: 9. In this case, the aspect ratio of the effective scanning period of the received signal matches the aspect ratio of the screen mask.

However, even in a wide aspect television receiver, the current NT having an aspect ratio of 4: 3 is used.
SC format video can be displayed. This current NT
When the second generation EDTV broadcast is displayed in the mode compatible with the SC system, the image is displayed only on a part of the center of the screen mask. Therefore, in order to effectively use the screen mask, it is necessary to switch the display mode depending on whether the received signal is the current NTSC system signal or the second generation EDTV signal.

Therefore, on the transmitting side, the second generation EDT is used.
It has been decided to multiplex and transmit an identification signal indicating that the V system broadcast signal is being transmitted. By detecting the identification signal, it is determined whether or not the second generation EDTV system broadcast signal is received, and the identification result is used to perform control corresponding to each broadcast system.

By the way, this identification signal is a GCR (ghost image) because a broadcast signal can be recorded by a magnetic recording / reproducing device (VTR) or the like and cannot be inserted in a vertical synchronization period already used for other purposes. Unlike the cancellation reference signal and the like, the signals are multiplexed in the period in which the video signal is inserted. Therefore, for the detection of the identification signal, it is not possible to use a method such as a simple level detection similar to the synchronization separation or a conventionally used detection method such as GCR signal extraction.

[0009]

As described above, no effective means for detecting an identification signal has been developed so far, and it is effective to control a television receiver by using the identification result of the identification signal. There was a problem that no means was developed.

The present invention has been made in view of the above problems, in which the identification signal is identified and the broadcast signal is the current NT.
It is an object of the present invention to provide a broadcast signal identification circuit capable of detecting whether it is an SC system signal or a second generation EDTV system signal.

Further, the present invention is based on the current NTSC broadcast signal.
It is an object of the present invention to provide a television receiver capable of performing optimum control based on a discrimination result of whether it is a system signal or a second generation EDTV system signal.

[Constitution of Invention]

According to a first aspect of the present invention, a broadcast signal identifying circuit multiplexes an identification signal composed of an identification code in an NRZ format and a color subcarrier format and a confirmation signal in a color subcarrier format. The second generation EDTV system broadcast signal or the NTSC system broadcast signal is input,
By detecting the capturing means for capturing the broadcast signal during the period in which the RZ format identification code is inserted, and detecting whether or not the broadcast signal captured by the capturing means is the NRZ format identification code. The broadcast signal identification according to claim 2 further comprising: identification means for identifying whether the broadcast signal is the broadcast signal of the second generation EDTV system or the broadcast signal of the NTSC system. The circuit receives a broadcast signal of the second generation EDTV system or a broadcast signal of the NTSC system in which an identification signal composed of an identification code of the NRZ format and the color subcarrier format and an identification signal of the color subcarrier format is multiplexed, and The capturing means for capturing the broadcast signal during the period in which the identification code of the NRZ format is inserted and the period in which the confirmation signal is inserted, and the broadcast signal captured by the capturing means are the NR. Whether the broadcast signal is the broadcast signal of the second generation EDTV system or the NTSC system by detecting whether the confirmation signal is included as well as detecting whether the broadcast signal is a format identification code. And a means for identifying whether the signal is a broadcast signal,
The broadcast signal identification circuit according to claim 3 of the present invention is a broadcast signal of the second generation EDTV system in which an identification signal composed of an identification code of the NRZ format and the color subcarrier format and a confirmation signal of the color subcarrier format is multiplexed. Alternatively, the broadcast is input during a period in which an NTSC broadcast signal is input and the NRZ format identification code is inserted, the confirmation signal is inserted, and the color subcarrier format identification code is inserted. Capturing means for capturing a signal, detecting whether or not the broadcast signal captured by the capturing means is the NRZ format identification code, and detecting whether or not the confirmation signal is included,
Identification means for identifying whether the broadcast signal is the broadcast signal of the second generation EDTV system or the broadcast signal of the NTSC system by detecting whether or not it is the identification code of the color subcarrier format. In the television receiver according to claim 11 of the present invention, an identification signal composed of an identification code of the NRZ format and the color subcarrier format and a confirmation signal of the color subcarrier format is multiplexed. A broadcast signal identification circuit that receives a broadcast signal of the second generation EDTV system or a broadcast signal of the NTSC system, detects the identification signal, and identifies whether the broadcast signal is the second generation EDTV system or the NTSC system. A control means for controlling the screen display based on the identification result of the broadcast signal identification circuit.

[0013]

According to the first aspect of the present invention, the broadcast signal is captured during the period when the NRZ format identification code is inserted by the capturing means. The NRZ format identification code indicates that the broadcast signal is of the second generation EDTV system. The identification means detects whether the broadcast signal captured by the capture means is an NRZ format identification code to determine whether the broadcast signal is an NTSC system signal or a second generation EDTV system signal. Identify.

In the second aspect of the present invention, the capturing means captures the broadcast signal in the period in which the NRZ format identification code or confirmation signal is inserted. The identifying means detects that the captured broadcast signal is an NRZ format identification code and also detects that the captured broadcast signal includes a confirmation signal, and determines whether the broadcast signal is an NTSC system signal. Alternatively, it is identified whether the signal is of the second generation EDTV system.

In claim 3 of the present invention, the intake means is N
The broadcast signal in the period in which the RZ format identification code, the color subcarrier format identification code, or the confirmation signal is inserted is captured. The identification means adds an identification code in the NRZ format to the captured broadcast signal,
Whether the broadcast signal is the NTSC system signal or the second generation EDTV system signal is discriminated depending on whether the confirmation signal or the color subcarrier type identification code is included.

In the eleventh aspect of the present invention, the broadcast signal identification circuit identifies whether the input broadcast signal is a second generation EDTV system signal or an NTSC system signal. Based on this identification result, the control means controls the screen display to obtain the optimum display.

[0017]

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 broadcast signal identification circuit according to the present invention.

The input terminal 1 uses the current NTSC system or the second
A composite video signal of the generation EDTV system is input. An identification signal is inserted in the broadcast signal of the second generation EDTV system. FIG. 2 is an explanatory diagram showing this identification signal. Figure 2 shows the 2nd generation EDTV provisional system (provisional) compiled by the EDTV Development Committee of the Broadcasting Technology Development Council.
It is disclosed by the material for explaining the configuration technology of.
FIG. 2 shows a waveform during the 1H period in which the identification signal is inserted.

The identification signal is at the top of the image area (22H,
285H) in the horizontal scanning period. The identification signal is
As shown in FIG. 2, it has bit areas B1 to B27 for 27 bits. The bit width of each bit is 7 SC, where SC is the color subcarrier period. Bit area B1 to B
An identification code for identifying the mode is assigned to 23,
A confirmation signal for determining the existing video signal is assigned to the bit areas B25 to B27.

Bit areas B1 and B2 are reference timing signals, and bit areas B3 and B4 are signals indicating whether or not letterbox display is performed.
5 is an undefined bit. These bit areas B1 to B5 and bit area B24 are NRZ (non-return zero).
Transmitted in the format. The identification codes of the bit areas B3 and B4 are "0" to indicate a normal system with an aspect ratio of 4: 3, and "1" to have an aspect ratio of 16: 9.
It shows the letter box method. Further, a reinforcement signal or the like for improving the image quality of the second generation EDTV broadcast is assigned to the bit areas B6 to B11.

Bit areas B6 to B23 and bit area B
25 to B27 are transmitted in color subcarrier format. The identification codes of the bit areas B6 to B23 are color subcarrier frequencies fsc (=
This is a signal of 3.579545 MHz). Bit area B
The confirmation signals of 25 to B27 have a frequency of 2.04 MHz (=
It is a sine wave of (4/7) fsc). The signals in these areas transmit control information according to the boundary phase of each bit area or the phase of the confirmation signal. For example, if it is in phase with the color burst phase, it is determined that the identification code is "0", and if it is in antiphase, it is determined to be "1".
That is, the identification result can be obtained by demodulating the signal transmitted in the color subcarrier format in the color burst phase.

The position of each bit area in the horizontal direction (time direction) is 50% of the level of the leading edge of the horizontal synchronizing signal, that is, 2
It is defined based on 0IRE. For example, for the bit area B1, as shown in FIG.
The timing to become IRE is defined as the start position, and this start position is set to the position of 33 SC with the leading edge of the horizontal synchronizing signal as a reference. The bit width of each bit area is 7
Since it is SC, the end position of the bit area B1 is (33+
7) SC. Similarly, the start position and end position of the nth bit area Bn are {33 + 7 (n-1)} SC = (26 + 7), respectively, with respect to the leading edge of the horizontal synchronizing signal.
n) SC and {33 + 7n) SC.

In FIG. 1, the composite video signal input through the input terminal 1 is given to the comparator 2. The comparator 2 is also provided with a predetermined reference value, and by comparing the level of the composite video signal with the reference value, N of the bit areas B1 to B5 of the identification signal is compared.
The RZ format signal is converted into “0” or “1” and output to the data processing circuit 3. That is, the comparator 2 determines a low level (hereinafter referred to as “L”) when the level of the identification signal is equal to or lower than the reference value, and a high level (hereinafter referred to as “H”) when the level is equal to or higher than the reference value. ) Is determined.

Timing pulses are also input to the data processing circuit 3. Timing pulse is 22H or 285H
Is a signal indicating a period of 33 to 68 SC, that is, a period of bit regions B1 to B5 with reference to the leading edge of the horizontal synchronizing signal of. Further, the data processing circuit 3 has a memory (not shown), which is set in the bit areas B1 to B5 when the second generation EDTV system and the letter box system video signal are transmitted to this memory. Value (the bit areas B3 and B4 are "1") is stored. The data processing circuit 3 uses the timing pulse to extract each signal of the five periods of the bit regions B1 to B5 from the input composite video signal. The data processing circuit 3 compares each of the signals in the five periods of the extracted bit areas B1 to B5 with the data stored in the memory,
The input composite video signal is discriminated whether it is of the NTSC system or the second generation EDTV system, and the discrimination result is outputted from the output terminal 4.

Next, the operation of the embodiment thus constructed will be described.

The composite video signal input via the input terminal 1 is supplied to the comparator 2. The composite video signal is compared with the reference value by the comparator 2 and waveform-shaped into “L” or “H”. The output of the comparator 2 is supplied to the data processing circuit 3.

The data processing circuit 3 also receives a timing pulse indicating the timing of the bit areas B1 to B5 of the identification signal. The data processing circuit 3 uses the timing pulse to set the 22H and 285H bit areas B.
Each signal in the five periods 1 to B5 is extracted. Now, it is assumed that the composite video signal input through the input terminal 1 is an NTSC signal. In this case,
The five signals extracted by the data processing circuit 3 in each period of the bit areas B1 to B5 are not the identification code of the second generation EDTV signal and do not match the data stored in the memory (not shown). As a result, the data processing circuit 3 identifies that the received signal is a signal of the NTSC system and outputs an identification result indicating that.

On the other hand, it is assumed that a signal of the second generation EDTV system is input to the input terminal 1. In this case, the data processing circuit 3 determines that the identification codes of the bit areas B3 and B4 among the signals of the five periods of the extracted bit areas B1 to B5 coincide with the data "1" stored in the memory. It is detected that the received signal is a letterbox type signal of the second generation EDTV method. This identification result is output via the output terminal 4.

As described above, in this embodiment, the data processing circuit 3 extracts each signal in the five periods of the bit regions B1 to B5, so that the received signal is an NTSC signal.
It is discriminated whether the system is the second-generation EDTV system or the letterbox system.

It should be noted that each signal of the five periods of the bit areas B1 to B5 extracted by the data processing circuit 3 is transferred to the microcomputer, and this microcomputer determines whether the received signal is the second generation EDTV system or not. You may. In this case, the data processing circuit does not need a memory.

FIG. 3 is a block diagram showing an embodiment of a television receiver incorporating the broadcast signal identification circuit of FIG.

The input terminal 9 has the current NTSC system and the second
A composite video signal of a second generation EDTV signal including a generation EDTV system is input. This composite video signal is supplied to the vertical blanking width switching circuit 11 and the broadcast signal identification circuit 10. The broadcast signal identification circuit 10 has the same configuration as that of FIG. 1, and outputs a determination result indicating whether the received signal is the current NTSC system signal or the second generation EDTV system letterbox system signal. Has become.

The vertical blanking width switching circuit 11 switches the vertical blanking width of the input composite video signal. That is, when the identification result indicates that the letterbox type signal is input, the vertical blanking width switching circuit 11 is 3/4 of the center in the vertical direction with respect to the input composite video signal. A blanking process is performed on a part (non-image part) other than the part to output the blanking process.

In the embodiment thus constructed,
The input composite video signal is a broadcast signal identification circuit
It is given to 10 and it is discriminated whether or not it is a letter box type signal of the second generation EDTV system. The vertical blanking width switching circuit 11 performs a blanking process on the input composite video signal based on the identification result.

Now, it is assumed that the aspect ratio of the display screen of the television receiver is 4: 3. Here, when an NTSC system signal is input through the input terminal 9, the vertical blanking width switching circuit 11 performs a normal blanking process on the input composite video signal, that is, a blanking for only the vertical blanking period. The ranking process is applied and the result is output.

Next, the input composite video signal is the second
It is assumed that the signal is a letterbox system signal of the generation EDTV system. Then, the blanking width switching circuit 11
Blanking processing is performed on the input composite video signal in a portion other than the central 3/4 portion in the vertical direction, that is, in a period corresponding to a non-image portion. As described above, in the letterbox system, the 3 /
An image with an aspect ratio of 16: 9 is projected on the portion 4 and the other portion is a non-image portion. In the present embodiment, since the blanking process is performed at the timing corresponding to the non-image part, even when the non-image part is disturbed by noise or the like, the screen noise of the non-image part and the flicker of the non-image part Can be prevented.

As described above, in this embodiment, the blanking process is performed based on the discrimination result indicating whether the received signal is the NTSC system signal or the second generation EDTV system letterbox system signal. Therefore, when performing letterbox display, it is possible to prevent screen noise in the non-image area and flicker in the non-image area. Since it is possible to prevent the non-image portion from disturbing the eyes, the image in the center of the screen becomes easy to see.

FIG. 4 is a block diagram showing another embodiment of the present invention. 4, the same components as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the vertical blanking width switching circuit 11
It differs from the embodiment of FIG. 3 in that a mute processing circuit 12 is adopted instead of the above.

The mute processing circuit 12 is a broadcast signal identification circuit
If the identification result from 10 indicates that the input composite video signal is the letterbox type signal of the second generation EDTV method, it is 3 /
The mute process is performed in a portion other than the portion 4, that is, in a period corresponding to the non-image portion.

In the embodiment thus constructed,
When a letterbox type signal of the second generation EDTV type is input, the area corresponding to the non-picture portion is subjected to mute processing.

It is obvious that the same effect as that of the embodiment of FIG. 3 can be obtained also in this embodiment.

FIG. 5 is a block diagram showing another embodiment of the present invention. 5, the same components as those of FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the vertical blanking width switching circuit 11
It differs from the embodiment of FIG. 3 in that an image enlargement processing circuit 13 is provided instead.

The image enlargement processing circuit 13 is a broadcast signal identification circuit.
If the identification result from 10 indicates that the input composite video signal is the second-generation EDTV method letterbox method signal, the input composite video is enlarged to display the effective image on the entire screen. It is designed to be applied to the video signal and output.

In the embodiment thus constructed,
The input composite video signal is given to the image enlargement processing circuit 13. Now, it is assumed that the aspect ratio of the display screen is 16: 9. When the input composite signal is a signal of the NTSC system, the image enlargement processing circuit 13 compresses the input composite signal in the horizontal direction and displays an image on the left and right sides of the screen, for example, the center 3/4 portion.

Here, it is assumed that a letterbox system signal of the second generation EDTV system is input. In this case, the image enlargement processing circuit 13 performs, for example, processing for multiplying the vertical amplitude by 4/3 based on the identification result. As a result, the effective screen is enlarged and displayed on the entire display screen. The image enlargement processing circuit 13 may enlarge the vertical amplitude by using a reinforcement signal for improving the resolution in the vertical direction, and display the entire screen mask.

As described above, in this embodiment, the image enlarging process is performed based on the discrimination result indicating whether the received signal is the NTSC system signal or the second generation EDTV system letterbox system signal. With an aspect ratio of 1
When displaying a letterbox system image on a display screen of 6: 9, the effective screen can be expanded to the entire screen mask and the screen mask can be effectively used.

Although the size of the image is changed by signal processing in this embodiment, it is obvious that the deflection processing may be controlled.

FIG. 6 is a block diagram showing a broadcast signal identification circuit according to another embodiment of the present invention. 6, the same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

The present embodiment differs from the embodiment of FIG. 1 in that a data processing circuit 23 is used instead of the data processing circuit 3 and a switch 21 and a PLL circuit 22 are added. A composite video signal of the current NTSC system or the second generation EDTV system is input to the input terminal 1. This composite video signal is supplied to the comparator 2 via the terminal a of the switch 21. In this embodiment, the composite video signal input to the input terminal 1 is also applied to the PLL circuit 22.

FIG. 7 is a block diagram showing a concrete structure of the PLL circuit in FIG.

The composite video signal from the input terminal 1 is given to the phase comparator 26 via the terminal 25 of the PLL circuit 22. The oscillation output of the voltage controlled oscillator 29 is also given to the phase comparator 26. The voltage controlled oscillator 29 oscillates at a predetermined free-running angular frequency when given a predetermined input voltage. Further, in the voltage controlled oscillator 29, when the input voltage changes from a predetermined input voltage, the oscillation frequency changes from the free-running angular frequency in proportion to the change in the input voltage.

The phase comparator 26 generates an error voltage based on the phase difference between the composite video signal and the oscillation output of the voltage controlled oscillator 29, and outputs it to the low pass filter 27. The low-pass filter 27 band-limits the error voltage and outputs it to the DC amplification circuit 28. The DC amplifier circuit 28 DC-amplifies the error voltage from the low-pass filter 27 and outputs it as an input voltage of the voltage-controlled oscillator 29, and also outputs it to the output terminal 30.

The PLL circuit 22 operates so that the oscillation output of the voltage controlled oscillator 29 is phase-locked with the signal input to the terminal 25. When the PLL circuit 22 is locked, the DC amplifier circuit
From 28, a voltage level output following the change in the frequency of the signal input to the terminal 25 is obtained. In this embodiment, the pull-in range of the PLL circuit 22 is set to the bit areas B25 to B27.
Confirmation signal frequency band (2.04MH
z), and the output voltage of the DC amplification circuit 28 when the PLL circuit 22 is locked is higher than the input voltage for oscillating the voltage controlled oscillator 29 at the free-running angular frequency, for example, a reference value given to the comparator 2. Set so that the voltage will be higher than that.

As a result, the PLL circuit 22 outputs an output of a voltage higher than the reference value from the terminal 30 when the confirmation signal is input through the terminal 25. During the period when the confirmation signal is not input, PL
Since the L circuit 22 is not locked, during this period,
The output of the PLL circuit 22 has a voltage level lower than the reference value. The output of the PLL circuit 22 is the switch 21.
Is supplied to the terminal b.

The switch 21 is supplied with a timing signal (not shown) and has a period of at least 33 to 68 SC with reference to the leading edge of the horizontal synchronizing signal, that is, the bit regions B1 to B.
In the period corresponding to 5, select terminal a and
Period of 1 to 222SC, that is, bit areas B25 to B
In the period corresponding to 27, the terminal b is selected. The signal from the terminal c of the switch 21 is waveform-shaped by the comparator 2 and then supplied to the data processing circuit 23.

Timing pulses are also input to the data processing circuit 23. The timing pulse has a period of 33 to 68 SC, that is, a period of bit regions B1 to B5 and a period of 201 to 222 SC with respect to the leading edge of the horizontal synchronizing signal,
That is, it is a signal indicating the period of the bit areas B25 to B27. The data processing circuit 23 has a memory (not shown), and the values set in the bit areas B1 to B5 when the second generation EDTV system and the letterbox system video signal are transmitted to this memory. (Bit areas B3 and B4 are "1") are stored. The data processing circuit 23 uses the timing pulse to extract each signal of the five periods of the bit regions B1 to B5 from the input composite video signal. The data processing circuit 23 compares each of the signals in the five periods of the extracted bit areas B1 to B5 with the data stored in the memory to determine whether the input composite video signal is of the NTSC system or the second generation EDTV. Identify if it is a scheme.

Further, in this embodiment, the data processing circuit 23 extracts the input of the period of the bit regions B25 to B27 using the timing pulse, that is, the output of the comparator 2 based on the output of the PLL circuit 22, Based on the signal level of the period, it is confirmed that the received signal is a signal of the second generation EDTV system. Data processing circuit 23
Discriminates whether the input composite video signal is of the NTSC system or the second generation EDTV system based on the input signals of the bit regions B1 to B5 and B25 to B27, and It is designed to output from the output terminal 4.

Next, the operation of the embodiment thus constructed will be described.

The input composite video signal is the switch 21
Is also given to the PLL circuit 22. The switch 21 selects the composite video signal from the input terminal 1 and supplies it to the comparator 2 in the period of the 22H or 285H bit regions B1 to B5, and outputs the output of the PLL circuit 22 in the period of the bit regions B25 to B27. Is supplied to the comparator 2.

The comparator 2 shapes the waveform by comparing the input signal with a reference value, and the data processing circuit 23
Output to. During the period of the bit areas B1 to B5, the data processing circuit 23 operates similarly to FIG. That is, the data processing circuit 23 inputs the signal of the second-generation EDTV system letterbox system when each signal of the five periods of the extracted bit regions B1 to B5 coincides with the data stored in the memory. If not, it is determined that an NTSC signal has been input.

Further, in the present embodiment, the confirmation signal transmitted in the bit areas B25 to B27 is also used to judge the broadcasting system. The PLL circuit 22 is 2.04 MH
The z band is set as the pull-in range, and when a signal in this frequency band is input to the terminal 25, it is locked and an output of a voltage higher than the reference value following the frequency change of the input signal is output.

Now, it is assumed that the composite video signal input to the input terminal 1 is an NTSC system signal.
In this case, the signal frequency input to the terminal 25 is usually 2.04M even in the period of the bit areas B25 to B27.
Since it is not in the Hz band, the output of the PLL circuit 22 becomes a voltage lower than the reference value. Therefore, in this case, the output of the comparator 2 becomes "L", and the data processing circuit 23 determines that the input composite video signal is an NTSC system signal.

On the other hand, it is assumed that the second generation EDTV system composite video signal is input to the input terminal 1. In this case, the 22nd and 285th bit areas B25
The period from B27 to B27 is a sine wave (confirmation signal) having a frequency of 2.04 MHz. During this period, the PLL circuit 22 locks to the input confirmation signal and outputs an output having a voltage higher than the reference value. The output of the PLL circuit 22 is supplied to the comparator 2 via the switch 21, and “H” is output from the comparator 2 to the data processing circuit 23. The data processing circuit 23 operates from the "H" output of the comparator 2 to the bit area B25.
To detect that a confirmation signal is included in the period from B27 to B27,
The input composite video signal is the second generation EDTV.
The signal is identified as a system signal, and the identification result is output terminal 4
Output to.

As described above, in this embodiment, the signals in the five periods of the bit areas B1 to B5 are extracted to determine whether the input composite video signal is the second-generation EDTV letterbox signal. It is determined whether or not the confirmation signal is included in the period of the bit areas B25 to B27 by using the PLL circuit 22, and the second generation E
It has been confirmed that the signal is a DTV system signal. NTSC
Depending on the type of video signal, the bit areas B1 to B5 may be input even when a composite video signal of the standard is input.
It is also conceivable that each signal in the five periods of (1) matches the data stored in the memory. However, in the present embodiment, a confirmation signal that is not included in a normal video signal is detected to identify whether or not it is the second generation EDTV system, which is more reliable than the embodiment of FIG. It can be identified.

Also in this embodiment, the data processing circuit 23 transfers the signals in the periods of the bit areas B1 to B5 and B25 to B27 to the microcomputer to determine whether the signals are of the second generation EDTV system. Obviously, it may be done.

FIG. 3 shows the broadcast signal identification circuit of this embodiment.
It is also clear that it can be applied to the television receiver of FIG.

FIG. 8 is a block diagram showing a broadcast signal identification circuit according to another embodiment of the present invention. In FIG. 8, the same components as those in FIG. 6 are designated by the same reference numerals and the description thereof will be omitted.

This embodiment is different from the embodiment of FIG. 6 in that a bandpass filter 31 and a peak hold circuit 32 are used instead of the PLL circuit 22. Bandpass filter 31 is 2.0
The pass band is 4 MHz, and 2.04 MHz from the composite video signal input through the input terminal 1.
The band signal is passed and output to the peak hold circuit 32. The peak hold circuit 32 holds the peak of the output of the bandpass filter 31 at the timing of the operation control pulse corresponding to the bit areas B25 to B27 and outputs it to the terminal b of the switch 21.

Next, the operation of the embodiment thus constructed will be described.

Whether or not the composite video signal input through the input terminal 1 is the second-generation EDTV letterbox type signal is determined based on the signals in the five periods of the bit areas B1 to B5. The operation to be performed is similar to that of the embodiment shown in FIG. That is, 22H and 285H bit areas B1 to B5 of the input composite video signal.
The signals in the five periods are supplied to the comparator via the switch 21, waveform-shaped, and supplied to the data processing circuit 23. The data processing circuit 23 extracts each signal in the five periods of the bit regions B1 to B5 based on the timing pulse and compares it with the data stored in the memory to determine whether or not the letterbox type signal is input. Identify.

Further, in the present embodiment, as in the embodiment of FIG. 6, the presence of the confirmation signal in the period of the bit areas B25 to B27 is also detected. That is, the input composite video signal is supplied to the band pass filter 31, and only the 2.04 MHz band signal is supplied to the peak hold circuit 32.

Now, the input composite video signal is NT
It is assumed that the signal is of the SC system. In this case, the input composite video signal does not include a sine wave in the 2.04 MHz band, so the output level of the bandpass filter 31 is low. The peak hold circuit 32 holds the peak of the output of the bandpass filter 31 at the timing corresponding to the bit areas B25 to B27 and outputs it to the terminal b of the switch 21. In this case, the output level of the peak hold circuit 32 is sufficiently low. The comparator 2 compares the input signal with a reference value and outputs "L" to the data processing circuit 23.
Thereby, the data processing circuit 23 confirms that the input composite video signal is an NTSC system signal.

On the other hand, the input composite video signal is the second
In the case of a signal of the generation EDTV system, the output of the bandpass filter 31 has a high level in the period of the bit areas B25 to B27. The peak hold circuit 32 holds the output of the bandpass filter 31 by an operation control pulse generated in the period of bit areas B25 to B27 and switches it.
Output to terminal b of 21. In this case, the output of the peak hold circuit 32 has a high level. The comparator 2 compares the output of the switch 21 with a reference value and outputs "1" to the data processing circuit 23. As a result, the data processing circuit 23 identifies the input composite video signal as the second-generation EDTV system signal.

As described above, in this embodiment, the same effect as that of the embodiment of FIG. 6 can be obtained. In addition, the data processing circuit 23 uses a microcomputer to make the determination, and FIG.
The broadcast signal discriminating circuit (1) can be applied to the television receiver shown in FIGS. 3 to 5 as in the embodiment shown in FIG.

Although the composite video signal of the broadcast signal is input to the input terminal 1 in the above embodiments, it is obvious that the luminance signal may be input separately. .

FIG. 9 is a block diagram showing a broadcast signal identifying circuit according to another embodiment of the present invention. 9, the same components as those in FIG. 6 are designated by the same reference numerals and the description thereof will be omitted.

The composite video signal input through the input terminal 1 is supplied to the YC extraction circuit 41. The YC extraction circuit 41 separates the input composite signal into a luminance signal and a carrier color signal. Further, the YC take-out circuit 41 has a second
When the signal of the generation EDTV system is input, the NRZ format part of the identification signal and the confirmation signal are separated together with the luminance signal, and the carrier color signal format part of the identification signal is separated together with the carrier color signal.

Luminance signal from the YC extraction circuit 41, NRZ
The type identification code and confirmation signal are given to the terminal a of the switch 43 and the PLL circuit 22, and the carrier color signal and the carrier color signal type identification code are given to the color signal processing circuit 42.

The color signal processing circuit 42 color-demodulates the input signal and outputs the BY color difference signal to the terminal b of the switch 43. Further, the color signal processing circuit 42 demodulates the identification code in the carrier color signal format and outputs it to the terminal b of the switch 43.

The switch 43 is switch-controlled by a timing signal (not shown), and has a period of 33 to 68 SC with reference to the leading edge of the horizontal synchronizing signal, that is, the bit regions B1 to B.
The terminal a is selected in the period of 5 and the terminal c is selected in the period of 201 to 222SC, that is, the period of the bit regions B25 to B27.
, And the terminal b is selected during the period of 68 to 201 SC, that is, the period of bit areas B6 to B24. switch
43 supplies the selected signal to the comparator 2 via the terminal d.

Similar to the data processing circuit 23 of FIG. 6, the data processing circuit 44 extracts each signal of the five periods of the bit regions B1 to B5 and compares it with the data stored in the memory (not shown) to determine the first signal. It is detected that a letterbox type signal of the second generation EDTV method is input, and whether or not a confirmation signal is inserted is detected depending on the level of the signal input during the period of bit areas B25 to B27. Further, the timing pulse input to the data processing circuit 44 also corresponds to the period of 68 to 201SC, that is, the period of the bit areas B6 to B24, and the data processing circuit 44 extracts the signals input in these periods. Then, the broadcasting system is determined based on the extracted signal.

For example, the vertical reinforcement signal is transmitted in the bit area B9 of the identification signal, and the error correction code is transmitted in the bit areas B18 to B23. That is, in this case, a signal of a predetermined input level is input to the data processing circuit 44 for each bit area. On the other hand, when an NTSC system signal is input, the output of the color signal processing circuit 42 is a BY color difference signal, and the level of the signal input to the data processing circuit 44 is bit in a normal image. It varies regardless of the area.

As a result, the data processing circuit 44 determines whether or not the signal in each period of the extracted bit areas B6 to B24 is each identification code of the identification signal and determines whether or not it is the signal of the second generation EDTV system. Identify. The data processing circuit 44 determines whether the input composite video signal is the NTSC system signal or the second generation E based on these determination results.
An identification signal indicating whether it is a DTV system signal is output terminal 4
Output to.

Next, the operation of the embodiment thus constructed will be described.

The composite video signal input through the input terminal 1 is supplied to the YC extraction circuit 41, and the luminance signal, the NRZ format identification code and the confirmation signal, the carrier color signal and the carrier color signal format identification code are supplied. Is separated into The switch 43 selects the terminal a during the bit regions B1 to B5 and selects the terminal c during the bit regions B25 to B27. The output of the switch 43 is waveform-shaped by the comparator 2 and given to the data processing circuit 44. The data processing circuit 44 detects that a letterbox type signal has been input based on each signal of the five periods of the bit regions B1 to B5, and inserts a confirmation signal based on the signals of the period of the bit regions B25 to B27. Is detected in FIG.
It is similar to the embodiment of.

In the present embodiment, the signals in the period of bit areas B6 to B24 are also used for identifying the broadcasting system. That is, Y
The carrier color signal from the C take-out circuit 41 and the identification code of the carrier color signal format are given to the color signal processing circuit 42. Now, the composite video signal input to the input terminal 1 is NTSC.
It is assumed to be a signal of the system. In this case, the color signal processing circuit 42 outputs a BY color difference signal. This B-
The Y color difference signal is applied to the comparator 2 via the switch 43 to be waveform-shaped, and then applied to the data processing circuit 44. The data processing circuit 44 extracts signals in the period of the bit areas B6 to B24 based on the timing pulse. In this case, the level change of the signal during this period is not in 7SC units, and the data processing circuit 44 identifies that the signal of the NTSC system has been input.

Here, it is assumed that a letterbox type signal of the second generation EDTV method is input to the input terminal 1. In this case, the output of the color signal processing circuit 42 during the period of the bit areas B6 to B24 becomes a predetermined high level or a predetermined low level. The output of the color signal processing circuit 42 is a switch
It is given to the data processing circuit 44 via 43 and the comparator 2. Bit area B6 input to the data processing circuit 44
The signals from B24 to B24 are signals whose level changes in units of at least 7 SC. As a result, the data processing circuit 44 detects that the signal in this period is a color subcarrier type identification code and outputs an identification signal indicating that the signal of the second generation EDTV system is input.

As described above, in this embodiment, the signal is of the NTSC system or the second generation ED based on the signals in the periods of the bit areas B1 to B5 and the bit areas B25 to B27.
Not only is the signal of the TV system identified, but also the signal of the period of the bit areas B6 to B24 is used to identify whether it is the signal of the NTSC system or the signal of the second generation EDTV system. Therefore, the identification accuracy can be improved as compared with the embodiment of FIG.

Also in this embodiment, the signals in the period of the bit areas B1 to B27 extracted by the data processing circuit 44 may be transferred to the microcomputer to identify the broadcasting system.

Also, this embodiment can be applied to the television receivers shown in FIGS. 3 to 5, as in the above embodiments.

FIG. 10 is a block diagram showing a broadcast signal identification circuit according to another embodiment of the present invention. In FIG. 10, the same components as those in FIGS. 8 and 9 are designated by the same reference numerals and the description thereof will be omitted.

This embodiment is different from the embodiment of FIG. 9 in that a bandpass filter 31 and a peak hold circuit 32 are provided in place of the PLL circuit 22.

The band pass filter 31 passes the 2.04 MHz band which is the frequency band of the confirmation signal, and the peak hold circuit 32 holds the peak value in the period of the bit areas B25 to B27 as in the embodiment of FIG. Is.

In the embodiment constructed as described above,
The brightness signal in the period of the bit areas B1 to B5 is switched by the switch 43.
The data is supplied to the comparator 2 via the waveform shaping circuit, and the data stored in the memory is compared by the data processing circuit 44 as in the embodiment of FIG. In addition, the signals in the period of the bit regions B6 to B24 are demodulated by the color signal processing circuit 42 and given to the data processing circuit 44 via the switch 43 and the comparator 2, which is the same as the embodiment of FIG. The circuit 44 determines whether the signal input during this period is a BY color difference signal or an identification code.

Furthermore, when the confirmation signal is input, a voltage higher than the reference value is supplied to the comparator 2 by the bandpass filter 31 and the peak hold circuit 32, as in the embodiment of FIG. The data processing circuit 23 detects whether or not the confirmation signal is inserted from the signal level in the period of the bit areas B25 to B27.

Other functions and effects are similar to those of the embodiment shown in FIG.

FIG. 3 shows the broadcast signal identifying circuit of this embodiment.
It is obvious that it can be applied to the television receiver of FIG.

In each of the above embodiments, the input composite signal, the luminance signal, the output of the PLL circuit 22 or the output of the peak hold circuit 32 is applied to the comparator 2 for waveform shaping, but the comparator 2 may be omitted. Is clear.

[0101]

As described above, the first and second aspects of the present invention are described.
According to Nos. 2 and 3, it is possible to identify the identification signal and detect whether the broadcast signal is the current NTSC system signal or the second generation EDTV system signal.

According to claim 11 of the present invention, the broadcast signal is a signal of the current NTSC system, or the second generation E
There is an effect that optimum control can be performed based on the result of discrimination as to whether the signal is a DTV system signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a broadcast signal identification circuit according to the present invention.

FIG. 2 is an explanatory diagram for explaining an identification signal.

FIG. 3 is a block diagram showing an embodiment of a television receiver according to the present invention.

FIG. 4 is a block diagram showing a television receiver according to another embodiment of the present invention.

FIG. 5 is a block diagram showing a television receiver according to another embodiment of the present invention.

FIG. 6 is a block diagram showing a broadcast signal identification circuit according to another embodiment of the present invention.

7 is a block diagram showing a specific configuration of a PLL circuit in FIG.

FIG. 8 is a block diagram showing a broadcast signal identification circuit according to another embodiment of the present invention.

FIG. 9 is a block diagram showing a broadcast signal identification circuit according to another embodiment of the present invention.

FIG. 10 is a block diagram showing a broadcast signal identification circuit according to another embodiment of the present invention.

[Explanation of symbols]

 3 ... Data processing circuit

Claims (14)

[Claims] 1. A second generation EDTV system broadcast signal or an NTSC system broadcast signal, into which an identification signal composed of an identification code of NRZ format and color subcarrier format and an identification signal of color subcarrier format is multiplexed, is input. , Capturing means for capturing the broadcast signal during a period in which the NRZ format identification code is inserted, and detecting whether or not the broadcast signal captured by the capture means is the NRZ format identification code. Therefore, the broadcast signal identifying circuit is provided with an identifying unit for identifying whether the broadcast signal is the broadcast signal of the second generation EDTV system or the broadcast signal of the NTSC system. 2. A second generation EDTV system broadcast signal or an NTSC system broadcast signal, into which an identification signal composed of an identification code in the NRZ format and the color subcarrier format and an identification signal in the color subcarrier format is multiplexed, is input. , Capturing means for capturing the broadcast signal during a period in which the identification code in the NRZ format is inserted and a period in which the confirmation signal is inserted, and the broadcast signal captured by the capturing means is in the NRZ format. Whether the broadcast signal is the broadcast signal of the second generation EDTV system or the NTSC system broadcast signal by detecting whether the identification signal is included and detecting whether the confirmation signal is included. And a discrimination means for discriminating whether or not the broadcast signal discrimination circuit. 3. A second-generation EDTV system broadcast signal or an NTSC system broadcast signal, into which an identification signal composed of an identification code of the NRZ format and the color subcarrier format and an identification signal of the color subcarrier format is multiplexed, is input. Capturing means for capturing the broadcast signal during a period in which the NRZ format identification code is inserted, a period in which the confirmation signal is inserted, and a period in which the color subcarrier format identification code is inserted, It is detected whether or not the broadcast signal captured by the capturing means is the NRZ format identification code, it is detected whether the confirmation signal is included, and the color subcarrier format identification code is detected. Whether the broadcast signal is the second generation EDTV system broadcast signal by detecting whether or not the NTS
A broadcast signal identifying circuit, comprising: an identifying unit for identifying whether the signal is a C type broadcast signal. 4. The identifying means is the second-generation EDTV.
A storage unit for storing a value set as an NRZ format identification code of an identification signal to be multiplexed with a broadcasting signal of a system, and comparing the output of the capturing unit with the value stored in the storage unit. The broadcast signal identification circuit according to any one of claims 1 to 3, wherein the system of the broadcast signal is identified by. 5. The capturing means includes means for shaping the waveform of the broadcast signal, and the identifying means comprises a determining means for determining the value of each bit of the NRZ format identification code, and the determining means. 5. The broadcast signal identification circuit according to claim 4, wherein the method of the broadcast signal is identified by comparing the determined value of each bit with the value stored in the storage means. 6. The identifying means has a phase-locked loop circuit composed of a phase comparator, a low-pass filter, a DC amplification circuit and a voltage controlled oscillator, and provides the output of the acquisition means to the phase-locked loop circuit. , Setting the pull-in range of the phase-locked loop circuit to the frequency band of the confirmation signal, and when the output of the acquisition means includes the confirmation signal, the output of the phase-locked loop circuit becomes a predetermined level. The broadcast signal identification circuit according to claim 2, wherein the system of the broadcast signal is identified by setting as follows. 7. The identifying means includes a filter having a pass band in a frequency band of the confirmation signal, and a peak hold circuit for holding a peak value of an output of the filter during a period in which the confirmation signal is inserted. 4. The broadcast according to claim 2, wherein the output of the capturing means is applied to the filter, and the system of the broadcast signal is identified based on the output of the peak hold circuit. Signal identification circuit. 8. The identifying means includes a color demodulating means for performing color demodulation of the broadcast code from the capturing means on the identification code in the color subcarrier format, and outputs the output of the capturing means to the color demodulating means. The broadcast signal identifying circuit according to claim 2, wherein the broadcast signal identifying system identifies the broadcast signal system based on the output of the color demodulation means. 9. The identification means identifies the broadcast signal system depending on whether or not the output of the color demodulation means changes in bit units of the identification code of the color subcarrier format. 8. The broadcast signal identification circuit according to item 8. 10. The capturing means, instead of the broadcast signal, captures a luminance signal or a carrier color signal separated from the broadcast signal.
Signal identification circuit according to item 1. 11. A second generation EDTV system broadcast signal or an NTSC system broadcast signal, into which an identification signal composed of an identification code in the NRZ format and the color subcarrier format and an identification signal in the color subcarrier format is multiplexed, is input. A broadcast signal identification circuit that detects the identification signal and identifies whether the broadcast signal is a second generation EDTV system or an NTSC system, and controls screen display based on the identification result of the broadcast signal identification circuit. A television receiver comprising: 12. The control means, when the identification result indicates that a broadcast signal of the second generation EDTV system is input, a blanking process for a non-picture part period of the broadcast signal. The method according to claim 1, wherein
1. The television receiver according to 1. 13. The control means, when the identification result indicates that a broadcast signal of the second generation EDTV system is input, performs a mute process on a non-picture part period of the broadcast signal. The television receiver according to claim 11, which is performed. 14. The control means, when the identification result indicates that a broadcast signal of the second generation EDTV system is inputted, enlargement for displaying an image on the broadcast signal over the entire screen. The television receiver according to claim 11, wherein processing is performed.