JPS5913481A - Device for compensating drop-out - Google Patents
Device for compensating drop-outInfo
- Publication number
- JPS5913481A JPS5913481A JP57123571A JP12357182A JPS5913481A JP S5913481 A JPS5913481 A JP S5913481A JP 57123571 A JP57123571 A JP 57123571A JP 12357182 A JP12357182 A JP 12357182A JP S5913481 A JPS5913481 A JP S5913481A
- Authority
- JP
- Japan
- Prior art keywords
- correlation
- video signal
- voltage
- dropout
- output
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/76—Television signal recording
- H04N5/91—Television signal processing therefor
- H04N5/93—Regeneration of the television signal or of selected parts thereof
- H04N5/94—Signal drop-out compensation
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Television Signal Processing For Recording (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は映像信号の記録再生装置におけるドロップアウ
トの補償装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dropout compensation device in a video signal recording/reproducing device.
一般にＶＴＲ等の記録再生装置においてドロップアウト
補償が行なわれておシ、再生ＦＭ信号の振幅が一定値以
下となるときをドロップアウトが発生したものとみなし
て、その期間の映像信号音１水平走査期間（以後１Ｈと
記す）前の映像信号と置き換えている。ところが、再生
ＦＭ信号の振幅低下が少ない（例えば−２０〜３０ ｄ
Ｂ ）間は再生映像信号のＳ／Ｎが再生ＦＭ信号の振幅
低下にともない低下し、一定値以下まで再生ＦＭ信号が
低下するとノイズのみになる。この様子を第１図に示す
、Ａは再生ＦＭ信号であシ、Ｂはその時の再生映像信号
に含まれるノイズ成分を表わしている。ここで第１図の
ｔ２ の期間の如く再生映像信号がノイズのみになる場
合はドロップアウト補償を行ない１Ｈ前の映像信号に置
換えなければならない。しかし同図ｔ１の期間の如く映
像信号のＳ／Ｎは劣化するが映像信号の方のレベルが高
いときは再生画像の垂直相関の強さによって１Ｈ前の映
像信号に置換えた方が画質として向上する場合と逆に低
下する場合がある。つまり標準カラーパーの如く垂直相
関の非常に強い画像の場合は再生映像信号ｆ、（ＩＨ前
と置換えても何んら問題がないが、文字等の垂直相関の
少ない画像においては１Ｈ前の映像信号と置き換えるこ
とにより本来白レベルで有ったところに黒レベルの信号
が置き換えられたりする。従って、垂直相関の少ない画
像部分においてはノイズが映像信号のレベル以下のとき
に映像信号’ｊｚｌＨ前と置き換えない方がよく、相関
の強い画像部分においてはある程度Ｓ／Ｎが劣化した場
合に１Ｈ前の映像信号に置き換える方がよいが従来ドロ
ップアウトの検出レベルは一定としており、これらを両
立できない欠点があった。In general, dropout compensation is performed in recording and reproducing devices such as VTRs, and when the amplitude of the reproduced FM signal falls below a certain value, it is assumed that a dropout has occurred, and the video signal sound 1 horizontal scan during that period is It is replaced with a video signal from a period before (hereinafter referred to as 1H). However, the amplitude drop of the reproduced FM signal is small (for example, -20 to 30 d
During the period B), the S/N of the reproduced video signal decreases as the amplitude of the reproduced FM signal decreases, and when the reproduced FM signal drops below a certain value, only noise appears. This situation is shown in FIG. 1, where A represents the reproduced FM signal and B represents the noise component contained in the reproduced video signal at that time. Here, if the reproduced video signal consists of only noise as in the period t2 in FIG. 1, dropout compensation must be performed and the video signal must be replaced with the video signal from 1H earlier. However, as shown in the period t1 in the figure, the S/N of the video signal deteriorates, but when the level of the video signal is high, the image quality improves by replacing it with the video signal from 1H earlier, depending on the strength of the vertical correlation of the reproduced image. In some cases it decreases, while in other cases it decreases. In other words, in the case of an image with a very strong vertical correlation such as a standard color par, the reproduced video signal f, (there is no problem in replacing it with the before IH), but in the case of an image with a low vertical correlation such as text, the reproduced video signal f, By replacing the signal, a black level signal is replaced where the original white level was.Therefore, in image parts with little vertical correlation, when the noise is below the level of the video signal, the video signal 'jzlH front' is replaced. It is better not to replace it, and it is better to replace it with a video signal from 1H earlier when the S/N deteriorates to some extent in image parts with strong correlation, but conventionally, the dropout detection level is fixed, and there is a drawback that these cannot be achieved at the same time. there were.
本発明は、前述のような問題点に鑑み、ド０ノブアウト
による画質の劣化をより軽減するために安価で容易なド
ロップアウト補償装置を提供せんとするものである。SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention aims to provide an inexpensive and easy dropout compensating device in order to further reduce the deterioration of image quality due to knock-out.
以下図面ｆｇ照して本発明の実施例をあげ説明する。Embodiments of the present invention will be described below with reference to drawing fg.
第２図は本発明の第１の実施例のブロック図であり、１
は記録再生装置の再生用のＦＭ復調器である、又４は映
像信号切り換え器（以後単にＳＷと記す）でドロップア
ウト検出時に出力映像信号をＦＭ復調器１の出力から１
Ｈ遅延器（以後ＤＬ１と記す）（５）の出力に切シ換え
る。更に相関検出器３はＦＭ復調器１出力の映像信号が
どの程度垂直相関があるかを検出するためのものであり
、 ＤＬｌ（５）は映像信号を１Ｈ遅延させるだめのも
のであり、ドロップアウト検出器２は再生ＦＭ信号より
ドロップアウトの発生を検出するためのものである。FIG. 2 is a block diagram of the first embodiment of the present invention.
4 is an FM demodulator for playback of the recording/reproducing device, and 4 is a video signal switching device (hereinafter simply referred to as SW) that changes the output video signal from the output of FM demodulator 1 to 1 when dropout is detected.
The output is switched to the output of the H delay device (hereinafter referred to as DL1) (5). Furthermore, the correlation detector 3 is used to detect how much vertical correlation there is in the video signal output from the FM demodulator 1, and the DL1 (5) is used to delay the video signal by 1H, and is used to prevent dropout. The detector 2 is for detecting the occurrence of dropout from the reproduced FM signal.
なお１０．１１はそれぞれ人、出力端子である。Note that 10 and 11 are a person and an output terminal, respectively.
入力端子１０より加えられた再生ＦＭ信号は、ドロップ
アウト検出器２に加えられると共にＦＭ復調器１で復調
され再生映像信号が得られる。通常（ドロップアウトの
発生時以外）はＳ Ｗ ４ ｆ介して端子１１に前記再
生映像信号が出力されるとともに、Ｄ Ｌ’ １ （５
１で１Ｈ遅延された信号がＳＷ４及び相関検出回路３に
加えられている。相関検出器３においては、ＦＭ復調器
１の出力とＤ Ｌ １ （Ｅ５１の出力との差、つ捷り
原信号と１Ｈ遅延信号との差を算出し、その絶対値を垂
直相関の強さとして出力し、ドロップアウト検出器２の
検出レベルを制御している。一方ドロップアウト検出器
２は、加えられた再生ＦＭ信号ｉＡＭ検波を行った後に
前記相関検出器３の出力・によって制御される電圧と比
較することによってドロップアウト期間を検出している
。ここでドロップアウト検出器２の検出レベルは相関検
出器３において垂直相関が弱いと検出したときに下がる
（再生ＦＭ信号振幅がよシ小さくなったときのみがドロ
ップアウトとみなす）ようにしている。次にドロップア
ウト検出器２で検出された信号によりＳＷＡを制御し、
ドロップアウト時に、Ｄ Ｌ １ （５１により１Ｈ遅
延された映像信号を端子１１に出力している。A reproduced FM signal applied from an input terminal 10 is applied to a dropout detector 2 and demodulated by an FM demodulator 1 to obtain a reproduced video signal. Normally (except when a dropout occurs), the reproduced video signal is output to the terminal 11 via SW 4 f, and D L' 1 (5
A signal delayed by 1H at 1 is applied to SW4 and correlation detection circuit 3. In the correlation detector 3, the difference between the output of the FM demodulator 1 and the output of D L1 (E51), the difference between the unswitched original signal and the 1H delayed signal are calculated, and the absolute value is calculated as the strength of the vertical correlation. and controls the detection level of the dropout detector 2. On the other hand, the dropout detector 2 is controlled by the output of the correlation detector 3 after performing iAM detection of the added reproduced FM signal. The dropout period is detected by comparing it with the voltage.Here, the detection level of the dropout detector 2 decreases when the correlation detector 3 detects that the vertical correlation is weak (the reproduced FM signal amplitude is very small). Then, the SWA is controlled by the signal detected by the dropout detector 2.
At the time of dropout, the video signal delayed by 1H by D L1 (51) is output to the terminal 11.
以上箱１の構成についてＤＬｌｉｌＨとして述べたが線
順次色信号のドロップアウト補償を行なう場合はＤＬｌ
は２Ｈの遅延時間となる。The configuration of box 1 was described above as DLlilH, but when performing dropout compensation for line-sequential color signals, DLlilH is used.
is a delay time of 2H.
次に、本発明の第２の実施例について第３図に示すブロ
ック図において述べる。この第２の実施例は第１の実施
例の構成に振幅制限器（以後リミッタと記す）８と遅延
器（以後ＤＬ２と記す）６を加え、第１の実施例におけ
るＤＬｌ（５１ｉ遅延器（以後ＤＬ１ ａと記す）５２
Ｌと遅延器（以後ＤＬ３と記す）７に分割したものであ
る。Ｄ Ｌ ２ （６１は相関検出器３及びドロップア
ウト検出器２０時間遅れを補なうためで数μｓｅｃ以下
であり、Ｄ Ｌ ３ （７］はＤ Ｌ ２ （６１と遅
延時間の等しいものである。又再生ＦＭ信号が非常に低
下しノイズが映像信号を大きく上まわったとき相関検出
器３の出力振幅が異状に大きくなるが、リミッタ８にお
いて、垂直相関の１つたくない映像信号が相関検出器３
に加えられた時の相関検出器３の出力レベル以下に制限
している。Next, a second embodiment of the present invention will be described with reference to the block diagram shown in FIG. This second embodiment adds an amplitude limiter (hereinafter referred to as limiter) 8 and a delay unit (hereinafter referred to as DL2) 6 to the configuration of the first embodiment, and adds an amplitude limiter (hereinafter referred to as DL2) 6 to the configuration of the first example. Hereinafter referred to as DL1 a)52
It is divided into L and a delay device (hereinafter referred to as DL3) 7. D L 2 (61 is several μsec or less to compensate for the time delay of the correlation detector 3 and dropout detector 20, and D L 3 (7) has the same delay time as D L 2 (61) .Furthermore, when the reproduced FM signal is extremely low and the noise greatly exceeds the video signal, the output amplitude of the correlation detector 3 becomes abnormally large, but the limiter 8 detects the correlation of the video signal that does not have one vertical correlation. Vessel 3
The output level is limited to below the output level of the correlation detector 3 when the signal is applied to the correlation detector 3.
次に、第１の実施例の詳細な構成について述べるが、Ｆ
Ｍ復調器１は一般的に記録再生装置に使用されるもので
あり、又ＤＬ１はガラス遅延素子又はＣＯＤ等を用いた
１Ｈ遅延回路としてカメラやＶＴＲ等に使用されており
、ＳＷ４は単なる映像信号の切り換え回路であり、これ
らは一般によく知られており説明を除き、本発明のポイ
ントである相関検出器３及びドロップアウト検出器２に
ついて、第４図に示す回路図を中心に第６図の波形図を
参照しながら述へる。Next, the detailed configuration of the first embodiment will be described.
The M demodulator 1 is generally used in recording and reproducing devices, the DL1 is used in cameras, VTRs, etc. as a 1H delay circuit using a glass delay element or COD, and the SW4 is used as a simple video signal. These are generally well-known switching circuits, and except for explanations, the main points of the present invention, the correlation detector 3 and the dropout detector 2, will be explained below with reference to the circuit diagram shown in FIG. This will be described with reference to waveform diagrams.
本実施例においては２ケの演算増幅器ＯＰ１ 。In this embodiment, there are two operational amplifiers OP1.
ＯＦ２及び整流回路ＤＩ 、Ｄ２ 、Ｒ７、Ｒ８。OF2 and rectifier circuit DI, D2, R7, R8.
Ｃ１で相関検出器３を構成しており、抵抗Ｒ１゜Ｒ２は
演算増幅器ＯＰ１の入力抵抗てＲ３はフィードバック抵
抗である、又抵抗Ｒ４，Ｒ５は演算増幅器ＯＰ２の入力
抵抗で抵抗Ｒ６はフィードバック抵抗である。ここでＦ
Ｍ復調器１から出力された映像信号ＶｏとＤ Ｌ １
（６）の出力映像信号ｖ１とは演算増幅器ＯＰ１ 、Ｏ
Ｆ２でそれぞれ［ＩＶｌ−ＶＯ、ｖｏ−ｖ １ ］の減
減算行なって第５図の（ｖｌ−ＶＯ）、及び（ｖＱ−ｖ
ｌ）の如き彼形を得ティる。さらにダイオードＤＩ、Ｄ
２及び抵抗Ｒ７によって負極性の信号のみを取り出すこ
とで、第５図のＣ−１Ｖ１−Ｖｏ（］に示される如きＦ
Ｍ復調器３の出力映像信号とＤ Ｌ １ （５１の出力
の差の絶対値を得ている、次に抵抗Ｒ８及びコンデンサ
Ｃ１よ構成る積分回路において第５図Ｓに示される如く
垂直相関の強さを電圧として得ている。C1 constitutes a correlation detector 3, resistors R1 and R2 are the input resistances of the operational amplifier OP1, and R3 is the feedback resistance, and resistors R4 and R5 are the input resistances of the operational amplifier OP2, and the resistor R6 is the feedback resistance. be. Here F
Video signal Vo output from M demodulator 1 and D L 1
The output video signal v1 in (6) is the operational amplifier OP1, O
At F2, subtract [IVl-VO, vo-v 1 ] respectively to obtain (vl-VO) and (vQ-v
You will get a figure like l). Furthermore, diodes DI, D
By extracting only the negative polarity signal using 2 and resistor R7, F as shown in C-1V1-Vo(] in FIG.
The absolute value of the difference between the output video signal of the M demodulator 3 and the output of D Strength is obtained as voltage.
ドロップアウト検出器２に加えられたＦＭ信号１は検出
レベル調整用抵抗Ｒ１６でレベル調整をした後増幅器Ａ
１に加えられる、ここで増幅器Ａ１はゲイ７２０〜３Ｑ
［ｄＢ］のＩＪ ミツター増幅器であり、入力信号の−
１０〜−２Ｑ〔ｄＢ〕でリミットしている、次にカノプ
リングコンテンザＣ２、入力抵抗Ｒ９，Ｒ１０、フィー
ドバンク用抵抗Ｒ１１及びダイオードＤ３．Ｄ４、演算
増幅器Ａ２より成る理想ダイオード整流回路で整流し、
抵抗Ｒ１２及びコンデンサＣ３で積分してＡＭ検波を行
なっている。たたし前述の如く、増幅器Ａ２はリミッタ
増幅器であり、再生ＦＭ信号の入力が一１０〜２ｏ［ｄ
Ｂ’：］ｌｌ下に低下した状態でのみエンベローブが検
出されている。次に前述の如くして得られた再生ＦＭ信
号のエンベローブはコンパレータＣＰ１の１入力端子に
加え、他の入力端子に加えられる検出基準レベルと電圧
比較してドロップアウトを検出している。ここで相関検
出器３の出力電圧は、垂直相関の完全なときを零電圧に
しておシ、垂直相関の少ない時は負極性の電圧増加とな
っており、垂直相関の強弱によってドロップアウトの検
出レベルをとの程度変化させるかを調整する、抵抗Ｒ１
３を介して、ボルテージフォローアＯＰ３に加え、イン
ピーダンス変換を行ない、ボルテージフォローアＯＰ３
の出力電圧と電源電圧との間を抵抗Ｒ１４，Ｒ１６で分
割した電圧をコンパレータＣＰ１の検出基準レベルとし
ている。The FM signal 1 applied to the dropout detector 2 is level-adjusted by the detection level adjustment resistor R16, and then sent to the amplifier A.
1, where amplifier A1 has a gain of 720~3Q
[dB] IJ Mitzter amplifier, input signal -
Next, the canopling condenser C2, input resistors R9, R10, feed bank resistor R11, and diode D3. D4, rectified by an ideal diode rectifier circuit consisting of operational amplifier A2,
AM detection is performed by integrating with a resistor R12 and a capacitor C3. However, as mentioned above, the amplifier A2 is a limiter amplifier, and the input of the reproduced FM signal is 110~2o [d
B': The envelope is detected only in the state lowered to below. Next, the envelope of the reproduced FM signal obtained as described above is voltage-compared with a detection reference level applied to one input terminal of the comparator CP1 and the other input terminals to detect dropout. Here, the output voltage of the correlation detector 3 is set to zero voltage when the vertical correlation is perfect, and becomes a negative polarity voltage increase when the vertical correlation is small. Dropout can be detected depending on the strength of the vertical correlation. Resistor R1 adjusts whether the level is changed to
In addition to the voltage follower OP3, impedance conversion is performed through the voltage follower OP3.
The voltage obtained by dividing the output voltage between the output voltage and the power supply voltage by resistors R14 and R16 is set as the detection reference level of the comparator CP1.
なお、垂直相関の完全画像のときにコンパレータＧＰ１
の検出基準レベルは電源電圧〔十Ｂ ’：１ＸＲ１４、
／（Ｒ１４＋Ｒ１５）となっている。Note that when the vertical correlation is complete, the comparator GP1
The detection reference level is the power supply voltage [10B': 1XR14,
/(R14+R15).
次に第２の実施例について述べる。Next, a second embodiment will be described.
第２の実施例全示す第３図のブロック図に示す如〈実施
するには、相関検出器３の積分回路（第４図Ｒ８及びＣ
１）の時定数を短かぐ（例えば１μｓ程度）設定し、ド
ロップアウト検出器のコンパレータＣＰ１にヒシテリシ
ス特性を持たせ、リミッタ８としてダイオードによるリ
ミッタ回路を個別し、数μｓの遅延器をＤ Ｌ ２ （
６）及びＤ Ｌ ３（７）に使用している。The second embodiment is implemented as shown in the block diagram of FIG. 3, which shows the entire second embodiment.
Set the time constant of 1) to be short (for example, about 1 μs), give the comparator CP1 of the dropout detector a hysteresis characteristic, install a separate limiter circuit using a diode as the limiter 8, and add a delay device of several μs to D L 2. (
6) and D L 3 (7).
以上のように本発明によれば垂直相関の強い画面を再生
しているときにドロップアウトの検出感度を高く設定し
ても、垂直相関の少ない画面を再生しているときのドロ
ップアウトの検出感度は下がるので、文字の多いような
画面でドロップアウト補償のやりすぎによる画質の劣化
が軽減される。As described above, according to the present invention, even if the dropout detection sensitivity is set high when a screen with strong vertical correlation is being played back, the dropout detection sensitivity is set high when playing back a screen with low vertical correlation. This reduces the deterioration in image quality caused by overdoing dropout compensation on screens with a lot of text.
又本発明の第２の実施例によれば相関の強弱の検出及び
ドロップアウトの検出の時間遅延が補償されるためと、
リミッタによりドロップアウト時の相関検出器の検出誤
差が少なくなるために、ドロップアウトの発生による画
質の劣化はさらに軽減される。Furthermore, according to the second embodiment of the present invention, the time delay in detecting the strength of correlation and detecting dropout is compensated;
Since the limiter reduces the detection error of the correlation detector at the time of dropout, the deterioration in image quality due to the occurrence of dropout is further reduced.
第１図はドロップアウト時の再生ＦＭ信号及び再生映像
信号に含まれるノイズの彼形図、第２図。
第３図はそれぞれ本発明の実施例におけるドロップアウ
ト補償装置のブロック図、第４図は同実施例の要部を示
す電気的結線図、第５図は同動作彼形図である。
１・・・・・・ＦＭ復調器、２・・・・・・ドロップア
ウト検出器、３・・・・・・相関検出器、４・・・・・
・映像信号切換え器、５．６Ｎ、６．７・・・・・・遅
延器、８・・・・・・リミッタ。
第１図
第２図
第３図
第４図
第５図FIG. 1 is a helical diagram of the noise contained in the reproduced FM signal and reproduced video signal at the time of dropout, and FIG. FIG. 3 is a block diagram of a dropout compensator according to an embodiment of the present invention, FIG. 4 is an electrical connection diagram showing the main parts of the embodiment, and FIG. 5 is a cross-sectional view of the same operation. 1...FM demodulator, 2...Dropout detector, 3...Correlation detector, 4...
・Video signal switch, 5.6N, 6.7... Delay device, 8... Limiter. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5
Claims (1)
れた第１の映像信号と第２の映像信号を作成する遅延手
段と、印加映房信号のレベルが検出レベルよシ低い期間
、ドロップアウト検出出力を発生するドロップアウト検
出手段と、前記ドロップアウト検出出力により前記第１
の映像信号と第２の映像信号を選択的に切換えて出力端
に導く切換手段と、前記第１の映像信号と第２の映像信
号との垂直相関に応じた検出出力を発生する相関検出手
段と、その相関検出手段の検出出力に応じて前記検出レ
ベルを変化せしめる手段とよりなるドロップアウト補償
装置。delay means for creating a first video signal and a second video signal that are delayed by an integral multiple of the horizontal scanning period relative to the input video signal; and dropout during a period when the level of the applied video signal is lower than the detection level. dropout detection means for generating a detection output; and a dropout detection means for generating a detection output;
switching means for selectively switching the video signal and the second video signal and guiding them to an output terminal; and correlation detection means for generating a detection output according to the vertical correlation between the first video signal and the second video signal. and means for changing the detection level according to the detection output of the correlation detection means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57123571A JPS5913481A (en) | 1982-07-14 | 1982-07-14 | Device for compensating drop-out |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57123571A JPS5913481A (en) | 1982-07-14 | 1982-07-14 | Device for compensating drop-out |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS5913481A true JPS5913481A (en) | 1984-01-24 |
Family
ID=14863869
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57123571A Pending JPS5913481A (en) | 1982-07-14 | 1982-07-14 | Device for compensating drop-out |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5913481A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03104390A (en) * | 1989-09-19 | 1991-05-01 | Toshiba Corp | Reproduction fm signal processing circuit |
| JPH04234308A (en) * | 1990-12-28 | 1992-08-24 | Kao Corp | Pack for makeup |
-
1982
- 1982-07-14 JP JP57123571A patent/JPS5913481A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03104390A (en) * | 1989-09-19 | 1991-05-01 | Toshiba Corp | Reproduction fm signal processing circuit |
| JPH04234308A (en) * | 1990-12-28 | 1992-08-24 | Kao Corp | Pack for makeup |
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