JPH11234631A - Second generation edtv identification circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a comparatively compact EDTV2 identification circuit with high precision at low cost that identifies a 2nd generation EDTV signal EDTV2. SOLUTION: The identification circuit is provided with a mean luminance detection circuit 112 that detects a mean luminance of an input video signal for one horizontal scanning period or within a prescribed period in addition to various detection circuits such as an NRZ detection circuit 111 for an EDTV2 identification control signal. The mean luminance level for 1H period from the mean luminance detection circuit 112 is fed to an upper lower non-image part extract circuit 113, which is used to detect upper/lower non-image parts that is a feature of the letter box form and the mean luminance level for the 1H period is fed to a 22.285H extract circuit 114, which detects a mean luminance level for 22nd and 285th H horizontal scanning periods where an EDTV2 identification control signal is in existence (EDTV2 detection). An overall discrimination circuit 121 totally discriminates detection results of NRZ pattern, upper/lower non-image parts, and mean luminance level at 22.285H.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a second generation EDTV.
The present invention relates to a television receiver capable of receiving a wide aspect broadcast called EDTV2 (hereinafter, referred to as EDTV2), and more particularly to a second generation EDTV identification circuit that performs identification determination of an EDTV2 signal that is a wide aspect broadcast.

[0002]

2. Description of the Related Art The EDTV2 system has a wide screen (aspect ratio 16: 9) and high image quality within a frequency bandwidth of one channel (6 MHz) while maintaining compatibility with the current NTSC television system. It is intended.

The EDTV2 system is composed of a video signal and an identification control signal. The broadcast station converts the signal source of the wide image into a letterbox signal with black at the top and bottom of the screen, and further superimposes a reinforcement signal to enhance the resolution on the non-picture part of this letterbox signal, and encodes the video signal And Information on these reinforcement signals is displayed at the top of the screen (the 22nd and 285th horizontal scanning periods;
85H). Both the video encode signal and the identification control signal are put together in a transmission format and transmitted from the broadcasting station. FIG. 3 shows a schematic diagram of this video encode signal.

The receiver receives information from the identification control signal, restores the multiplexed augmented signal, decodes the signal, and displays the decoded signal on a cathode ray tube (CRT). An identification control signal is indispensable for decoding a video signal, and both the video signal and the identification control signal are transmitted as one.

[0005] The video signal is composed of a main picture portion and a reinforcement signal. 4: 3 wide 16: 9 image as the signal source in the main picture area
Is arranged in a reduced form at the center of the screen. Therefore, the number of scanning lines is converted to 3/4. The letterbox format is used in order to make it possible to view the image content even in the current NTSC receiver which cannot decode the EDTV2 signal. In the case of the current receiver, the image quality is lower than the image quality of the EDTV2, but the original wide screen (letter box screen) having blackness at the top and bottom of the screen can be displayed without being cut off.

The reinforcement signal is composed of a vertical high frequency component VH (Vertical
High component), vertical time component VT (Vertical-Temp
oral component), HH (Horizontal Hig)
hcomponent), which are used for higher image quality. The combination of VH and VT is also called a vertical reinforcement signal. The vertical reinforcement signals (VT, VH) are subjected to predetermined processing, and are multiplexed into non-image portions provided above and below the main image portion as shown in FIG. HH is frequency-multiplexed to the main picture section. The VT signal is for facilitating the restoration of the progressive scanning signal on the receiver side by transmitting a vertical time component (VT) that is lost when the progressive scanning signal is converted into an interlaced scanning signal during encoding. is there. VH
The signal is intended to prevent the deterioration of the vertical resolution by transmitting the vertical high frequency component (VH) in the main picture portion which is lost by the letterboxing, thereby reproducing the signal on the receiving side. E
In DTV2, the video frequency band is 4.2 MHz, which is the same as NTSC, in order to maintain compatibility with NTSC. The HH signal is ED
Since the screen of TV2 is horizontally long, when viewing a display having the same screen height from the same viewing distance as compared with NTSC, the horizontal resolution of EDTV2 deteriorates in the same frequency bandwidth. The horizontal high-frequency component (HH) of 4 to 6 MHz is frequency-multiplexed in the 4.2 MHz band of the main picture portion, and the band of the decoded image is expanded on the receiving side.

[0007] These three reinforcement signals (VT, VH, H
H) can be used alone or in any combination. That is, the broadcast station can independently select each reinforcement signal. In this case,
Since the identification control signal has a bit for giving the presence or absence of each augmentation signal, it is necessary to control the corresponding bit according to the presence or absence. The reinforcement signal can be freely selected even at the receiver, and it is not always necessary to decode using all the reinforcement signals transmitted from the broadcasting station.

The discrimination control signal can be determined at the beginning of a field, and is inserted into the uppermost ends 22H and 285H of each field having little effect on the screen. The identification control signal is an aspect ratio of 16: 9 in EDTV2 broadcasting.
And mode control information indicating the display mode of the image and the types of the VT, VH, and HH reinforcement signals, and control information indicating the phase reference signal. In addition, a confirmation function is also transmitted for discrimination from a normal video signal. The broadcasting station superimposes the identification control signal on the video signal together with the reinforcement signal, and the receiver obtains the display form and phase reference information based on the identification control signal, thereby correctly demodulating the multiplexed reinforcement signal. Can be.

FIG. 4 shows an outline of the waveform of the identification control signal. The identification control signal is composed of 27 bits (B1 to B27). The waveforms B1 to B5 and B24 are NRZ (Non-Return-to-Zero) in consideration of application to a VTR or the like, and indicate the position of a video signal and the type of screen display. B6-B
The waveform 23 is a sine wave of fsc (approximately 3.58 MHz, setup 0) in consideration of the influence of the ghost on the confirmation function, and has information such as the type of the reinforcement signal. B25 ~
The waveform of B27 is a continuous (4/7) fsc sine wave, and is a confirmation signal used to determine whether it is an identification control signal or a normal video signal. B3 to B17 are identification codes, which indicate the aspect ratio and the presence or absence of a reinforcement signal. B
Reference numerals 18 to B23 denote CRC codes for performing transmission line error detection / correction of the identification code.

When a receiver having a display capability of a wide aspect ratio of 16: 9 receives an EDTV2 video signal, in the case of a receiver having an EDTV2 decoder, it is determined as an EDTV2 signal based on the identification control signal. If high quality aspect ratio 16: 9 using the reinforcement signal
Play the image of. Or, wide aspect ratio 16: 9
In the case of a receiver having the display capability of (1) and not having an EDTV2 decoder, the image quality is not improved by the augmentation signal, but the display surface is expanded so that the vertical amplitude is widened and the main image portion is displayed on the entire screen. Use effectively.

On the other hand, a conventional receiver having an aspect ratio of 4: 3, which does not have a display capability of a wide aspect ratio of 16: 9, has
When a DTV2 broadcast is received, an image based on the letterbox signal is displayed. In other words, the aspect ratio is 4: 3
A non-image portion is provided above and below the screen, and an image having an aspect ratio of 16: 9 is displayed so as to be sandwiched between the non-image portions. At this time,
The reinforcement signal multiplexed with the scanning signal during the scanning period of the non-image portion may appear in the non-image portion, and may make the viewer uncomfortable. For this reason, in a conventional receiver having an aspect ratio of 4: 3, when it is determined that a received broadcast signal is an EDTV2 broadcast, it has been proposed to mask a non-picture part displayed in the upper and lower portions of the screen. I have.

By the way, as described above, the identification control signal of the EDTV2 broadcast includes various signals, and in consideration of the signal conditions of the EDTV2,
The 2 detection can be performed by detecting NRZ, fsc, (4/7) fsc, DC level (such as B24), or CRC error correction code, or by detecting non-image portions at the top and bottom of the screen. For example, as described in the specification of Japanese Patent Application No. 8-173712, the most accurate EDTV2 detection becomes possible by detecting all of them and making a comprehensive judgment.

FIG. 5 shows a conventional example of an EDTV2 identification circuit. In FIG. 5, an image input terminal 201 has an EDTV
A video signal on which the two identification control signals are superimposed is supplied. E
The DTV2 discrimination control signal is transmitted once every one field cycle in a specified one horizontal scanning period (22H or 28H).
5H). This input terminal 201 is
It is connected to the second EDTV2 signal identification circuits 210 and 220. The first EDTV2 signal identification circuit 210
Whether or not the condition of the V2 identification control signal or the EDTV2 signal is met can be detected relatively stably and easily. The NRZ detection circuit 211 and the upper and lower non-image portion detection circuit 212 are provided. The second EDTV2 signal identification circuit 220 outputs an EDTV2 identification control signal or an EDTV
Whether the condition of the two signals is met is detected with relatively high accuracy and high difficulty that cannot be easily obtained. The 4/7 fsc detection circuit 221 and the fsc detection circuit 222 , DC level detection circuit 223, CRC error correction code detection circuit 224, and fsc / fv standard decision detection circuit 225.

In the NRZ detection circuit 211, the period of bit 1 to bit 5 (B1 to B5) and bit 24 (B24), which are the NRZ signals, of the 27 bits of the above-described identification control signal is high, as shown in FIG. Row arrangement, that is, 0 shown in FIG.
Whether or not the video signal is multiplexed with the EDTV2 identification control signal is detected based on whether or not the IRE (low level) or 40 IRE (high level) is arranged.

The upper / lower non-picture part detection circuit 212 determines whether or not the video signal is an EDTV2 identification control signal depending on whether or not the above-described vertical reinforcement signal is detected in the upper and lower non-picture parts of the displayed video. Is detected.

The 4/7 fsc detection circuit 221 is arranged at the rear of the effective video scanning line signal (video signal) for one horizontal scanning period (1H), centering on the pedestal level, which is multiplexed as an EDTV2 identification control signal confirmation signal. , 4/7 fsc (2.
04MHz) is detected, and the 4 /
Whether or not the video signal is an EDTV2 identification control signal is detected based on whether or not a signal other than 7 fsc is at the pedestal level.

The fsc detection circuit 222 outputs fsc only during a period corresponding to the identification control signals B6 to B23 (see FIG. 4).
By detecting that a sine wave signal of sc (color subcarrier frequency) is multiplexed, the video signal is converted to an EDTV2
This is to detect whether the signal is an identification control signal.

The DC level detection circuit 223 detects, for example, the DC level of the signal in the B24 (see FIG. 4) of the NRZ of the identification control signal, or detects the sync tip level in the front porch, and determines whether or not it matches the pedestal level. Whether the video signal is EDT
This is for detecting whether or not the signal is a V2 identification control signal.

The CRC error correction code detection circuit 224 calculates the CRC of 15 bits of information bits from B3 to B17 of the identification control signal, and outputs the result (value) and
By detecting whether or not the six bits B18 to B23 of the identification control signal from the transmission source (broadcasting station) of the video signal match the CRC value transmitted as a CRC code, the video signal is detected. This is to detect whether the signal is an EDTV2 identification control signal.

The fsc / fv standard judgment detection circuit 225
It does not directly detect the DTV2 identification control signal, but detects whether or not the frequency fsc of the burst signal, which is the reference for the frequency and phase of the color subcarrier of the video signal, is synchronized with the frequency fv of the vertical synchronization signal. In the video displayed on the screen by the video signal, the vertical reinforcement signal (VT, VH) multiplexed in the non-image portion at the top and bottom of the screen and the horizontal reinforcement signal (HH) frequency-multiplexed in the main image portion are output. This condition is indispensable in order to demodulate, improve the image quality in addition to the main image portion, and process it as an EDTV2 video signal.

Each output of the first and second EDTV2 signal discriminating circuits 210 and 220 is output to the next-stage comprehensive judgment circuit 23.
0. The comprehensive determination circuit 230 comprehensively determines EDTV2 including the periodicity, and outputs the determination result from the output terminal 202.

The result of this judgment is highly accurate,
Even when the vertical and horizontal reinforcement signals are demodulated to improve the image quality in addition to the main image, no hindrance is caused, and signal conditions such as S / N can be determined.

However, when it is not necessary to demodulate the vertical and horizontal reinforcement signals to achieve high image quality in addition to the main image, the accuracy is not required. For example, in the case of the above-described receiver having a display capability of a wide aspect ratio of 16: 9 and not having an EDTV2 decoder,
At the time of EDTV2 broadcast reception, by controlling the vertical deflection circuit to increase the vertical amplitude to 4/3 times, only the control for displaying a full screen is performed, and high image quality is not achieved by the vertical and horizontal reinforcement signals. Also, 4/7 fsc detection, fsc detection, CRC
The error correction code detection and the fsc / fv standard decision detection require demodulation at respective frequencies and phases, which increases the hardware scale and is disadvantageous in cost.

Therefore, simply, the 4/7 fsc detection circuit 22
1, fsc detection circuit 222, DC level detection circuit 223,
The CRC error correction code detection circuit 224 and the fsc / fv standard decision detection circuit 225 are omitted, and the NRZ detection circuit 21 is omitted.
If the detection is performed by relying solely on the upper and lower non-image part detection circuit 212, there is a problem that the possibility of erroneous detection increases if the detection accuracy of the two detection circuits 211 and 212 cannot be obtained.

[0025]

As described above, the conventional E
The DTV2 discrimination circuit is disadvantageous in terms of cost due to a large hardware scale. Further, if only the NRZ detection circuit and the upper and lower non-image portion detection circuits are used, the possibility of erroneous detection increases if the detection accuracy is not obtained. There was a problem of becoming.

The present invention has been made in view of the above problems, and
An object of the present invention is to provide an EDTV2 discriminating circuit which is relatively small in circuit size, has a small number of erroneous detections, and is advantageous in terms of cost.

[0027]

According to the first aspect of the present invention, E is provided.
The DTV2 discriminating circuit is configured to perform the second
The video signal on which the generation EDTV identification control signal is superimposed is input, and various signals constituting the second generation EDTV identification control signal or various detection means for detecting signals related to identification of the second generation EDTV identification control signal are included. At least one first detection unit and a video signal on which a second generation EDTV identification control signal is superimposed are input for one horizontal scanning period or one horizontal scanning period.
An average luminance detecting means for detecting an average luminance level in a predetermined period in the horizontal scanning period; and a horizontal scanning period from the average luminance detecting means or an average luminance level in the predetermined period sequentially input thereto, and a video signal field is inputted. At least one second level detecting that an average luminance level in a predetermined horizontal scanning period in a period or a frame period is smaller than a predetermined value.
Detection means, and a detection result from the first detection means,
And a comprehensive determination means for comprehensively determining whether or not the input video signal is a second generation EDTV broadcast signal based on the detection result from the second detection means.

In the EDTV2 discriminating circuit according to the second aspect of the present invention, as set forth in claim 2, the first detecting means according to claim 1 is an NRZ detecting circuit, a 4/7 fsc detecting circuit, an fsc detecting circuit, or It is a CRC error correction code detection circuit.

In the EDTV2 discriminating circuit according to the third aspect of the present invention, as set forth in claim 3, the second detecting means in the first aspect is configured such that the second detecting means detects one horizontal scanning period from the average luminance detecting means or a predetermined period thereof. Of the horizontal scanning periods corresponding to upper and lower non-image portions in a field period or a frame period of a video signal, and that the average luminance level in one horizontal scanning period is equal to or less than a predetermined value. An upper / lower non-image portion extraction circuit for detecting the upper and lower non-image portions by detecting, and one horizontal scanning period from the average luminance detecting means or an average luminance level within a predetermined period thereof are sequentially inputted, and a field period in a video signal is input. Alternatively, it is detected that the average luminance level in each of the 22nd and 285th horizontal scanning periods in the frame period is equal to or lower than a predetermined value.
2.285H extraction circuit.

According to the first, second and third inventions, the EDT
V2 discriminating control signal various detecting circuits, for example, an NRZ detecting circuit, an average luminance detecting circuit for detecting an average luminance level in one horizontal scanning period or a predetermined period of the input video signal is provided. By supplying the average luminance level for the 1H period to the upper and lower non-image portion extraction circuit, upper and lower non-image portion detection, which is a feature of the letterbox format, is performed, and the average luminance level for the 1H period from the average luminance detection circuit is calculated. By supplying the EDTV2 to the 22.285H extraction circuit, EDTV2 detection accompanying the detection of the average luminance level in the 22Hth and 285Hth horizontal scanning periods with the EDTV2 identification control signal is also performed. The overall judgment circuit 121 detects the NRZ pattern by the NRZ detection circuit, the upper and lower non-image part detection by the upper and lower non-image part extraction circuit,
285H extraction circuit detects the average luminance level of 22 and 285H, and comprehensively judges the detection results.
TV2 identification can be performed.

An EDTV2 identification circuit according to a fourth aspect of the present invention, as described in claim 4, inputs a video signal on which a second generation EDTV identification control signal is superimposed, and outputs a second generation EDTV identification signal.
Various signals constituting the TV identification control signal or the second generation E
At least one of various detection means for detecting a signal related to the identification of the DTV identification control signal, and a video signal on which a second generation EDTV identification control signal is superimposed, and one horizontal scanning period Alternatively, an average luminance detecting means for detecting an average luminance level in a predetermined period in the one horizontal scanning period, and an average luminance level in one horizontal scanning period or in the predetermined period from the average luminance detecting means are sequentially inputted, Pattern detection for detecting patterns of letterbox signals of various aspect ratios by detecting the number of horizontal scanning lines whose average luminance level for each horizontal scanning period is equal to or less than a predetermined value in a field period or a frame period of a signal. Means, and an average luminance level in one horizontal scanning period or a predetermined period from the average luminance detecting means are sequentially inputted, and At least one second detecting means for detecting that an average luminance level in a predetermined horizontal scanning period in a field period or a frame period is smaller than a predetermined value; a detection result from the first detecting means; And a comprehensive determination means for comprehensively determining whether or not the input video signal is a second generation EDTV broadcast signal based on a detection result from the second detection means.

According to the fourth invention, the same effect (accurate EDTV2 discrimination) as in the first to third inventions can be performed, but it is possible to detect letterbox signal patterns of various aspect ratios. Therefore, in a receiver having a display capability of a wide aspect ratio of 16: 9, various aspect ratios of a letterbox signal are detected, and a vertical deflection circuit (not shown) is controlled in accordance with the detected aspect ratio to control the vertical direction. By automatically controlling the amplitude, it is possible to always display the main image portion with a full screen even for letterbox signal inputs having various aspect ratios.

According to a fifth aspect of the present invention, in the EDTV2 identification circuit, the average luminance detecting means according to the first or fourth aspect outputs a video signal on which a second generation EDTV identification control signal is superimposed. The horizontal scanning period is divided into a plurality of blocks, an average luminance level is detected, and a maximum value among the average luminance levels is used as a detection result.

According to the fifth aspect, even if the configuration of the average luminance detecting means is changed as described above, the same effects as those of the first to fourth aspects can be obtained.

[0035]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an ED according to an embodiment of the present invention.
It is a block diagram which shows a TV2 identification circuit.

In FIG. 1, a video input terminal 101 has
A video signal on which the EDTV2 identification control signal is superimposed is supplied. The EDTV2 identification control signal is multiplexed once per one field cycle in a predetermined horizontal scanning period (22H or 285H). This input terminal 101
Are supplied to the NRZ detection circuit 111 as the first detection means and the one horizontal scanning period (1H) average luminance detection circuit 112 as the average luminance detection means.

In the NRZ detection circuit 111, the period of bit 1 to bit 5 (B1 to B5) and bit 24 (B24), which are the NRZ signals, of the 27 bits of the above-described identification control signal is high, as shown in FIG. Row arrangement, that is, 0 shown in FIG.
Whether or not the video signal is multiplexed with the EDTV2 identification control signal is detected based on whether or not the IRE (low level) or 40 IRE (high level) is arranged. Although it is relatively easy to determine whether the signal is an EDTV2 identification control signal by this method, the identification control signal is NTS
Since it is during the video period in the C video signal 1H, the EDTV2 discrimination control signal is detected a predetermined number of times because the normal video signal and the discrimination control signal may be erroneously recognized. It is desirable to confirm, that is, confirm periodicity (repetition). Note that whether or not the video signal is an EDTV2 signal (whether it is a full mode signal or a letterbox signal) is determined by the B of the NRZ signal.
It is determined whether 3 is low level or high level. A high level is a letterbox signal. The 1H average luminance detection circuit 112 detects the average luminance of the video signal during a 1H period or a predetermined period within the 1H period. For example, the 1H average luminance detection circuit 112
Video average level in H = 1 Complete integral value in 1H period / 1
H period = average luminance (IRE) is output. The detection output of the 1H average luminance detection circuit 112 is
13 and 22 · 285H extraction circuit 114 are supplied to a second detection means. The second detection means sequentially inputs the 1H period or the average luminance level within a predetermined period of the 1H period from the 1H average luminance detection circuit 112, and outputs the image signal in a predetermined horizontal scanning period in a field period or a frame period of a video signal. It comprises at least one circuit means for detecting that the average luminance level is smaller than a predetermined value.

The upper and lower non-image portion extraction circuit 113 sequentially inputs the 1H period or the average luminance level within a predetermined period of the 1H period from the 1H average luminance detection circuit 112, and outputs the upper and lower portions in the field period or frame period of the video signal. The upper and lower non-image portions are detected by detecting that the 1H average luminance level in a plurality of horizontal scanning periods corresponding to the non-image portions is equal to or less than a predetermined value. Regarding the 1H average luminance level, the average luminance level of all predetermined number of horizontal scanning periods (upper and lower 30 horizontal scanning periods in the field period and upper and lower 60 horizontal scanning periods in the frame period) corresponding to the upper and lower non-image portions is equal to the 1H average luminance level. If the value is equal to or less than a predetermined value (equal to or less than a predetermined IRE), there is a non-image portion,
It can be determined as a DTV2 letterbox signal.
This means that the non-image area is always 0IR compared to the main image area or video area.
This is because it has a luminance close to E.

The 22 · 285H extraction circuit 114 sequentially inputs the 1H period from the 1H average luminance detection circuit 112 or the average luminance level within the predetermined period, and identifies the odd and even fields constituting the frame. If the average luminance level of the control signal in each horizontal scanning period (22H, 285H) is equal to or less than a predetermined value (not more than a predetermined IRE), E
DTV2 is determined.

This is because the average luminance in the video periods of 22H and 285H is, as is clear from FIG. 4, the average luminance (IRE) = 40 [IRE] × 3 [bit period] ÷ 27 [bit period] = about This is because the IRE value is as low as 4.4 [IRE].

Therefore, the 22 · 285H extraction circuit 114
Is 22 of the outputs from the 1H average luminance detection circuit 112.
H, 285H, the average luminance is extracted, and it is determined whether or not the extracted value is, for example, 4.4 IRE or less.
If it is less than or equal to E, it can be determined that it is EDTV2.

The NRZ detection circuit 11 described above
The three outputs of the upper and lower non-image portion extraction circuit 113 and the 22 · 285H extraction circuit 114 are supplied to the overall judgment circuit 121. The comprehensive determination circuit 121 performs accurate EDTV2 identification by comprehensively determining (final determination) the NRZ pattern, the upper and lower non-image portions, and the DC level of 22 · 285H, and outputs the EDTV 2 from the output terminal 102.

Here, the comprehensive judgment circuit 121 may be realized by using any means (circuit or the like).
As the comprehensive judgment circuit 121, it is relatively easy to change, examine, and evaluate the algorithm at the time of design, and it can be realized by a microcomputer that is generally widely used.

The overall judgment circuit 121 includes, for example, the detection result of the NRZ detection circuit 111 and the upper and lower non-image portion extraction circuit 113
EDTV2 determination logic means for calculating the logical product of the detection result of the EDTV2 and the detection result of the 22 · 285H extraction circuit 114;
The logic output from the DTV2 determination logic means is monitored for a predetermined period, during which time the EDTV2 identification control signal is detected with a predetermined probability or higher (or whether a signal other than the EDTV2 identification control signal is detected), By looking at
And a periodicity detecting logic means for outputting the EDTV2 identification result.

The EDTV2 determination logic means includes an NRZ detection circuit 111, upper and lower non-image portion extraction circuits 113, 22, and 28.
The logical product of the three discrimination outputs from the 5H extraction circuit 114 is obtained, and the result is supplied to the periodicity detection logic means. The periodicity detection logic means detects and determines an EDTV2 identification control signal;
That is, the periodicity (repetition) is checked for a predetermined period, and the ratio of the EDTV2 identification control signal to the number of all the fields in the predetermined period is detected. As a result, when the EDTV2 identification control signal is detected at a predetermined ratio or more with respect to the total number of fields (or E
Only when no signal other than the DTV2 discrimination control signal is detected), it is determined that the signal supplied via the EDTV2 discrimination logic means is the EDTV2 discrimination control signal. In this manner, a high-quality EDTV2 identification control signal (video signal) determination result can be obtained at high speed and accurately.

By the way, in a receiver having a display capability of a wide aspect ratio of 16: 9, in addition to detecting an EDTV2 broadcast, a general letterbox signal image having various aspect ratios is detected and matched with the aspect ratio. It is necessary to automatically control the vertical amplitude as in
It is also necessary to use the two detections and the letterbox video detection of various aspect ratios in combination.

FIG. 2 shows an EDTV according to another embodiment of the present invention.
FIG. 3 is a block diagram illustrating a 2 identification circuit.

In this embodiment, the 1H average luminance detection circuit 112 shown in FIG. 1 is used not only for detecting EDTV2 broadcasts but also for detecting letterbox patterns.

FIG. 2 differs from FIG. 1 in that the output of the 1H average luminance detecting circuit 112 is
13 and 22 · 285H extraction circuit 114, and also to a pattern detection circuit 115 for detecting a letterbox pattern. Here, the 1H average luminance detecting circuit 112 and the pattern detecting circuit 115 constitute a letterbox detecting circuit 131. The pattern detection circuit 115 stores in advance the ratio of the upper and lower non-image portions to the display screen according to various aspect ratios, and the average luminance for each 1H period sequentially supplied from the 1H average luminance detection circuit 112 is a predetermined value. By counting the number of scanning lines that are equal to or less than the value, and calculating the ratio of the counted number to the number of effective scanning lines, it is possible to detect which aspect ratio the pattern of the letterbox signal is, and output the detection result to the output terminal 116. Output as output 2. Alternatively, the pattern detection circuit 115 stores in advance the number of horizontal scanning lines in the upper and lower non-image portions according to various aspect ratios, and supplies the average luminance for each 1H period sequentially supplied from the 1H average luminance detection circuit 112. By counting the number of scanning lines where is less than or equal to a predetermined value, the aspect ratio of the letter box signal pattern is detected, and the detection result is output to the output terminal 116 as output 2.

In the above configuration, the video input terminal 101
The input video signal on which the EDTV2 identification control signal is superimposed is supplied to the 1H average luminance detection circuit 112 in the NRZ detection circuit 111 and the letterbox detection circuit 131, respectively. The following detection of EDTV2 is the same as in FIG. That is, the NRZ detection circuit 111, the upper and lower non-image portion extraction circuit 113, and the 22 / 285H extraction circuit 114
The output of the two circuits is subjected to accurate EDTV2 discrimination by comprehensively determining the three of the NRZ pattern, the upper and lower non-image portions, and the DC level of 22 · 285H by the comprehensive determination circuit 121.
It is output as output 1 from the DTV2 determination output terminal 102.

At the same time, the pattern detection circuit 115 sequentially supplies 1
By counting the number of scanning lines whose average luminance for each H period is equal to or less than a predetermined value, and calculating the ratio of the counted number to the number of effective scanning lines, it is possible to detect which aspect ratio of a letterbox signal pattern is detected. The detection result
It can be output to the output terminal 116 as output 2.

According to the present embodiment, in a receiver having a display capability of a wide aspect ratio of 16: 9, a letterbox signal having a main picture portion of various aspect ratios is detected, and the detected aspect ratio is determined. By automatically controlling the vertical amplitude by controlling a vertical deflection circuit (not shown) corresponding to the ratio, the main image area is always displayed on the full screen even for letterbox signal inputs with various aspect ratios. Can be.

As a configuration of the 1H average luminance detection circuit, in addition to the configuration of the 1H average luminance detection circuit described in the two embodiments of FIGS. 1 and 2, for example, the 1H period is divided into a plurality of blocks. However, even with a circuit configuration in which the maximum value in each block is used as a detection value (representative value), similar performance can be obtained for EDTV2 identification.

[0054]

As described above, according to the present invention, the ED
As for the TV2 identification, an EDTV2 identification circuit with a relatively small circuit scale, high accuracy, and cost advantages can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an EDTV2 identification circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an EDTV2 identification circuit according to another embodiment of the present invention.

FIG. 3 is a schematic diagram of an encode signal.

FIG. 4 is a schematic diagram of an identification control signal waveform.

FIG. 5 is a block diagram showing a conventional EDTV2 identification circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 ... Video input terminal 102 ... EDTV2 judgment output terminal 111 ... NRZ detection circuit 112 ... 1H average luminance detection circuit 113 ... Upper / lower non-image part extraction circuit 114 ... 22 / 285H extraction circuit 115 ... Pattern detection circuit 116 ... Letterbox pattern detection output Terminal 121: comprehensive judgment circuit 131: letter box detection circuit

Claims (5)

[Claims] 1. A video signal on which a second generation EDTV identification control signal is superimposed is input, and various signals constituting the second generation EDTV identification control signal or signals related to identification of the second generation EDTV identification control signal are detected. And a video signal on which a second-generation EDTV identification control signal is superimposed, and receives one horizontal scanning period or an average of a predetermined period in the one horizontal scanning period. An average luminance detecting means for detecting a luminance level; and a horizontal scanning period from the average luminance detecting means or an average luminance level within the predetermined period sequentially input thereto, and a predetermined horizontal scanning in a field period or a frame period of a video signal. At least one second detection unit that detects that an average luminance level in a period is smaller than a predetermined value; and a detection result from the first detection unit. And a detection result from the second detection means, the input video signal is the second
A second generation EDTV identification circuit, comprising: comprehensive determination means for comprehensively determining whether a broadcast signal is a generation EDTV broadcast signal. 2. The method according to claim 1, wherein the first detecting means includes an NRZ detecting circuit,
2. The second generation EDTV identification circuit according to claim 1, wherein the circuit is a 4/7 fsc detection circuit, an fsc detection circuit, or a CRC error correction code detection circuit. 3. The second detecting means sequentially inputs an average luminance level within one horizontal scanning period or a predetermined period from the average luminance detecting means, and outputs the average luminance level during a field period or a frame period in a video signal. An upper and lower non-image portion extraction circuit for detecting upper and lower non-image portions by detecting that an average luminance level in one horizontal scanning period of a plurality of horizontal scanning periods corresponding to non-image portions is equal to or less than a predetermined value; Means for sequentially inputting the average luminance level within one horizontal scanning period or a predetermined period thereof, and outputting the second luminance level in the field period or frame period of the video signal.
2. The second generation EDTV identification circuit according to claim 1, further comprising a 22.285H extraction circuit for detecting that an average luminance level in each of the 285th horizontal scanning periods is equal to or less than a predetermined value. 4. A video signal on which a second generation EDTV identification control signal is superimposed, and detects various signals constituting the second generation EDTV identification control signal or signals related to the identification of the second generation EDTV identification control signal. And a video signal on which a second-generation EDTV identification control signal is superimposed, and receives one horizontal scanning period or an average of a predetermined period in the one horizontal scanning period. An average luminance detecting means for detecting a luminance level; and sequentially inputting an average luminance level within one horizontal scanning period or a predetermined period from the average luminance detecting means, and outputting one horizontal signal during a field period or a frame period in a video signal. By detecting the number of horizontal scanning lines where the average luminance level for each scanning period is equal to or less than a predetermined value, letterbox signals of various aspect ratios are detected. Pattern detecting means for detecting a turn; and sequentially inputting one horizontal scanning period from the average luminance detecting means or an average luminance level within a predetermined period thereof, and in a predetermined horizontal scanning period in a field period or a frame period of a video signal. At least one second detection means for detecting that the average luminance level of the second detection means is smaller than a predetermined value, a detection result from the first detection means, and a detection result from the second detection means. Video signal is
A second generation EDTV identification circuit, comprising: comprehensive determination means for comprehensively determining whether a broadcast signal is a generation EDTV broadcast signal. 5. An EDT according to claim 2, wherein said average luminance detecting means is a second generation EDT.
A video signal on which a V discrimination control signal is superimposed is inputted, one horizontal scanning period is divided into a plurality of blocks, an average luminance level is detected, and a maximum value among the average luminance levels is used as a detection result. The second generation EDTV identification circuit according to any one of claims 1 to 4, wherein