JPH0937185A - Identification control signal discrimination circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate the identification control signals of the wide images of EDTV-II by a circuit constituted of relatively inexpensive parts. SOLUTION: Luminance signals are separated from video signals 1 in a Y signal separation part 2 and amplified to a required level in an amplifier 3, sync tip clamping is performed in a clamping part 4, slicing is performed at a 20IRE level in a comparator 6 and NRZ(nonreturn to zero) codes 2 are extracted. 22H and 285H are detected in a 22H and 285H detection part 10 and the rise of the NRZ codes from the comparator is detected with the rise of H-sync as a reference in the respective H in a rise detection part 11. The five pieces of sampling pulses 3 are generated in the cycle of 7fcs from the rise of the NRZ codes in a sampling pulse generation part 12 and impressed to an NRZ code discrimination part 13, the NRZ codes (five bits) from the comparator are sampled and I/O is discriminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discriminating control signal discriminating circuit, which detects a discriminating control signal of EDTV-II (wide clear vision) and uses a letter box type (aspect ratio 9:16) video signal. Regarding what determines whether or not there is.

[0002]

2. Description of the Related Art A widescreen T with an aspect ratio of 9:16
In the V receiver, when displaying an image with an aspect ratio of 3: 4, a black frame is left on the left and right sides of the image to display with an aspect ratio of 3: 4, or the left and right edges are stretched to make an apparent appearance. Some images are displayed as wide images. When EDTV-II (wide clear vision) signals, which are about to start broadcasting soon, are wide images with an aspect ratio of 9:16 (letterbox method) and are displayed on a wide screen with an aspect ratio of 9:16. The EDTV-II identification control signal indicating that it is a letterbox type signal is superimposed on the video signal and broadcast, and the receiving side determines this identification control signal.
By switching the circuit (deflection circuit or the like in the case of the cathode ray tube type), the EDTV-II letterbox type image can be displayed in a normal state on the wide screen. By the way, the circuit for discriminating this EDTV-II discrimination control signal is
Some use a / D converter or the like. EDTV-
In the II identification control signal, a signal for improving the image quality of the TV receiver is superimposed in addition to the signal indicating the letterbox system, but if the signal for EDTV-II is displayed on a wide screen, the signal is It suffices to be able to determine whether or not it is the letter box system. For this reason, the use of relatively expensive parts such as an A / D converter increases the cost and raises the cost of the product.

[0003]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention is to enable the EDTV-II identification control signal to be discriminated by using a small-scale circuit configuration of relatively inexpensive parts.

[0004]

In order to solve the above-mentioned problems, the present invention solves the above-mentioned problems by NRZ (nonret
urn to zero) NRZ extraction section for slicing and extracting the code at a required level, an NRZ superposition period detection section for detecting a horizontal scanning period in which the NRZ code is superposed, and a signal from the NRZ superposition period detection section A rising edge detecting section for detecting the rising edge of the NRZ code from the NRZ extracting section, a sampling pulse generating section for generating a pulse for sampling the NRZ code with the signal from the rising edge detecting section as a reference, and the NRZ extracting section. Of the NRZ code of NRZ
An identification control signal discriminating circuit configured by an NRZ code discriminating unit for discriminating a code is provided.

[0005]

With the above construction, in the discrimination control signal discriminating circuit according to the present invention, the luminance signal is separated from the received / demodulated video signal, and the luminance signal is clamped at the leading end of the horizontal synchronizing signal. The data of each bit of the NRZ part of the EDTV-II identification control signal is extracted by slicing at the setting level of, the rising edge of bit 1 is detected, and 5 pulses with a period of 7 fsc are generated from the rising edge of bit 1, and this pulse is generated. At NRZ, the bits of the NRZ portion are sampled to determine whether or not the received video signal is of letterbox type.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an identification control signal discriminating circuit according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of essential parts of an embodiment of an identification control signal discrimination circuit according to the present invention. In the figure, 1 is a video signal, 2 is luminance (Y)
The signal separation unit inputs the video signal 1 to the luminance signal separation unit 2 and separates the luminance signal. Reference numeral 3 denotes an amplifier, which amplifies the amplitude of the brightness signal from the brightness signal separating unit 2 to a required amplitude. A clamp unit (SYNC TIP CLAMPER) 4 clamps the luminance signal from the amplifier 3 at the tip of the horizontal synchronizing signal. Reference numeral 5 is a reference level (voltage), which is a voltage corresponding to, for example, 20IRE. Reference numeral 6 denotes a comparator, which slices the signal from the clamp unit 4 at a reference level 5 (20IRE), and outputs "1" when it is 20IRE or more and "0" when it is 20IRE or less.

Reference numeral 7 is a horizontal / vertical synchronizing signal (H / V-sync), 8
Is an odd field / even field signal (odd / ev
en) and 9 are system clocks. 10 is 22
The H, 285H detection unit counts H-sync based on V-sync7 and detects the 22nd H (the 22nd horizontal scanning period) of the odd field and the 285H of the even field. Reference numeral 11 is an NRZ code rising edge detection section, which is 33 fsc from the trailing edge of each of the 22H and 285H horizontal sync signals detected by the 22H and 285H detection section 10.
(Color subcarrier cycle) The rising edge of the NRZ code output from the comparator 6 is detected within ± 5 fsc. Reference numeral 12 is a sampling pulse generator, which generates 5 pulses of a period of 7 fsc from the rising edge of the first bit of the NRZ code detected by the NRZ code rising edge detecting section 11. Reference numeral 13 denotes an NRZ code discriminating unit which samples the NRZ code from the comparator 6 by the pulse from the sampling pulse generating unit 12 and discriminates 1/0.

Next, the operation of the discrimination control signal discrimination circuit according to the present invention will be described. The EDTV-II identification control signal is superimposed on the 22nd H of the odd field and the 285H of the even field, and the NRZ part of this identification control signal is, as shown in FIG. 2, pedestal level (0) of the video signal (luminance signal). ) Is "0" and 40IRE is "1", which is an NRZ format signal and is composed of 5 bits as shown in.
As shown in FIG. 3, the content of the code is that bit 1 is “1”,
Bit 2 is "0" and both are fixed data. Bit 3 and bit 4 are both "1" in the case of letterbox format, "0" in the case of aspect ratio 3: 4, and bit 5 is "0". Has become.

The video signal 1 demodulated by the reception of television broadcasting or the like is input to the luminance signal separating section 2 and the luminance signal is separated. Due to this separation, ± 20 around the pedestal level
Color subcarrier superimposed with IRE amplitude (Fig. 2B)
Is removed and the reference level 20IRE by the comparator 6 described later
The color subcarrier does not mix when slicing in
This does not hinder the discrimination of the NRZ code. The luminance signal from the luminance signal separating unit 2 is amplified to a required amplitude by the amplifier 3 and input to the clamp unit 4 so that it can be sliced normally by the subsequent comparator 6, as shown in FIG. , Clamp at the tip of H-sync (SYNC TIP). The clamped luminance signal is applied to the comparator 6, and the 22nd H of the odd field and the 285H of the even field are applied.
N superposed with an amplitude of 1 (40IRE) and 0 (0IRE)
The RZ code is sliced at the reference level 5 (20IRE) to extract the waveform.

Then, the 22H, 285H detection unit 10 causes V-sync
H-sync is counted from the falling edge of the
The 22nd H corresponding to the Hth and the 285H corresponding to the 19th H of the even field are detected. This signal is input to the rising edge detector 11, and as shown in FIG. 2, 33 fs from the falling edge of H-sync.
The rising edge of the NRZ code from the comparator 6 input during the period of c ± 5fsc is detected. Fall detection period is regular 33fsc
However, the width of ± 5 fsc is provided in order to prevent the detection from being disturbed even when the output waveform of the comparator 6 is distorted. Input the signal from the rising edge detection section 11 to the sampling pulse generation section 12 and use this signal as a reference for 7fcs.
5 sampling pulses having a period of are generated.
This sampling pulse is input to the NRZ code discriminating unit 13, the NRZ code from the comparator 6 is sampled, and N
RZ code 1, 0 is discriminated.

A signal from the NRZ code discriminating unit 13 is applied to a required circuit (a deflection circuit or the like in the case of a cathode ray tube type) to switch the aspect ratio of the display screen or the enlargement circuits of the left and right ends, and the EDTV. -For II signals, display in a normal state on a wide screen with an aspect ratio of 9:16.

[0012]

As described above, according to the discrimination control signal discriminating circuit of the present invention, it is possible to discriminate a wide image of EDTV-II without using a relatively expensive A / D converter. It is possible to suppress an increase in cost.

[Brief description of drawings]

FIG. 1 is a block diagram of an essential part of an embodiment of an identification control signal discrimination circuit according to the present invention.

FIG. 2 is a diagram showing a waveform and a sampling pulse of an NRZ portion of an EDTV-II identification control signal.

FIG. 3 is a list of commands in an NRZ part of an EDTV-II identification control signal.

[Explanation of symbols]

 2 Luminance (Y) signal separation section 4 Clamp section 5 Reference level (20IRE) 6 Comparator 10 22H, 285H detection section 11 NRZ section Rise detection section 12 Sampling pulse generation section 13 NRZ code discrimination section

Claims (8)

[Claims] 1. An EDTV-II superimposed on a video signal.
An NRZ extraction unit that extracts the NRZ code of the identification control signal by slicing at a required level, an NRZ superimposition period detection unit that detects a horizontal scanning period in which the NRZ code is superposed, and an NR
A rising edge detecting section for detecting the rising edge of the NRZ code from the NRZ extracting section in response to a signal from the Z superposition period detecting section, and a pulse for sampling the NRZ code with the signal from the rising edge detecting section as a reference is generated. A discrimination control signal discriminating circuit comprising a sampling pulse generating section and an NRZ code discriminating section for discriminating the NRZ code by sampling the NRZ code from the NRZ extracting section with a pulse from the sampling pulse generating section. 2. The NRZ extraction unit includes a luminance signal separation unit that separates a luminance signal from a video signal, a clamp unit that clamps the luminance signal from the luminance signal separation unit, and a signal from the clamp unit at a required level. The discrimination control signal discriminating circuit according to claim 1, comprising a comparator for slicing and extracting an NRZ code. 3. The discrimination control signal discriminating circuit according to claim 2, wherein the clamp section clamps the luminance signal at a tip of a horizontal synchronizing signal. 4. The discrimination control signal discriminating circuit according to claim 2, wherein the comparator slices the luminance signal from the clamp section at a required slice level and outputs 1/0 data. . 5. The NRZ superposition period detector detects the 22nd horizontal scanning period of the odd field and the 285th horizontal scanning period of the even field with reference to the horizontal synchronizing signal and the vertical synchronizing signal input together with the video signal. The identification control signal discriminating circuit according to claim 1, claim 2, claim 3, or claim 4, 6. The rising detection unit is the 22nd horizontal scanning period or the 28th horizontal scanning period detected by the NRZ superposition period detection unit.
The rising edge of the NRZ code output from the NRZ extraction unit is detected during 33 color subcarrier cycles ± 5 color subcarrier cycles from the start of each horizontal synchronization signal in 5 horizontal scanning periods. The identification control signal discriminating circuit according to claim 2, claim 3, claim 4, or claim 5. 7. The method according to claim 1, wherein the sampling pulse generator is configured to generate 5 pulses of a 7-color subcarrier cycle from the rising edge of the NRZ code detected by the rising edge detecting portion. The identification control signal determination circuit according to claim 3, claim 4, claim 5, or claim 6. 8. The NRZ code discriminating unit has a built-in shift register, stores the NRZ code obtained by sampling in the shift register, and discriminates data 1 or data 0. Claim 3, Claim 4,
The identification control signal determination circuit according to claim 5, 6, or 7.