JPS59140608A - Nonlinear emphasizing circuit - Google Patents

Abstract

PURPOSE:To obtain the desired nonlinear emphasis characteristics even with a small input signal by connecting a series circuit consisting of a filter circuit and a nonlinear circuit in parallel to an amplifier and adding a phase inverting circuit to said series circuit or amplifier. CONSTITUTION:When a signal Vi is supplied to an input terminal 1, the signal of (a) shown in the diagram is supplied to the input terminal of an amplifying circuit 3. The signal of (b) is delivered to the output terminal of a phase inverting circuit 4. If the voltage gain of the circuit 3 is defined as (n), the signal V2 is turned into a signal which is (n) times as much as the signal V1 with 180 deg. phase inversion. The signal applied to both terminals of a series circut consisting of diodes D1 and D2 and a capacitor C2 is set at (n+1)V1 as shown by (c). Thus the signals of (n+1) times as much as those of a conventional nonlinear emphasizing circuit are supplied to both terminals of said series circuit. As a result, the amplitude is also (n+1) times as much as the conventional value at both terminals of diodes D1 and D2 respectively. Therefore the signal Vi which is used to obtain the characteristics equivalent to those of a conventional circuit can be reduced down to 1/n+1.

Description

【発明の詳細な説明】 く技術分野〉 本発明は入力信号のレベル及び周波数に対して非線形な
利得特性を備えた非線形強調回路に関する。特に、映像
信号を記録媒体上に記録するのに好適な非線形強調回路
に関する。DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a nonlinear emphasizing circuit having gain characteristics that are nonlinear with respect to the level and frequency of an input signal. In particular, the present invention relates to a nonlinear enhancement circuit suitable for recording video signals on a recording medium.

〈従来技術の説明〉 映像信号を磁気テープ上に記録、該テープ上から再生す
る磁気記録再生装ｆ（以下ＶＴＲ）においては装置の小
皺化、及び磁気テープの使用量を削減等の為に高密度記
録が要求されている。<Description of the Prior Art> In magnetic recording and reproducing equipment f (hereinafter referred to as VTR) that records video signals on magnetic tape and reproduces them from the tape, high-performance devices have been developed in order to reduce wrinkles in the device and reduce the amount of magnetic tape used. Density records are required.

高密度記録を達成する為には記録トラック巾を狭くする
、或はテープの搬送速度を遅くする等が考えられるが何
れも再生ビデオ信号のＳ／ＩＪが劣化する。In order to achieve high-density recording, it is possible to narrow the recording track width or slow down the tape conveyance speed, but either of these methods will degrade the S/IJ of the reproduced video signal.

又、一般に％ＶＴＲでは輝度信号を周波数の高域側［Ｆ
Ｍ変調して記録しているが、ＦＭ変調による記録再生に
おいては、三角ノイズ、変調ノイズを改善する為に、変
調して記録する前に高周波はど強調して記録する強調回
路が用いられる。Also, in general, in %VTR, the luminance signal is transferred to the high frequency side [F
Recording is performed with M modulation, but in recording and reproduction using FM modulation, an emphasis circuit is used that emphasizes and records high frequencies before modulating and recording in order to improve triangular noise and modulation noise.

最近では上記高密度化にともない８ハを更に改善する為
入力レベルに応じてエンファシス量が変化するいわゆる
非線形強調回路が採用される様になった。Recently, with the increase in density, a so-called non-linear emphasizing circuit, in which the amount of emphasis changes depending on the input level, has come to be used to further improve the 8H.

かかる非線形強調回路として、例えば第１図に示す回路
が知られている。図において、１は入力端子、２は出力
端子、Ｒ１，Ｒ２は抵抗、ｃ、。As such a nonlinear emphasizing circuit, for example, the circuit shown in FIG. 1 is known. In the figure, 1 is an input terminal, 2 is an output terminal, R1 and R2 are resistors, and c.

Ｃ２はコンデンサ、　Ｄｌ、Ｄ２はダイオードである。C2 is a capacitor, and Dl and D2 are diodes.

入力端子に大振巾の信号が供給されるとダイオードＤ４
．Ｄ２の両端の振巾も大になシダイオードＤ　、　、Ｄ
２は導通し、Ｄｌ、Ｄ２の等価抵抗は小さくなる。また
入力に小振巾の信号が供給されるとダイオードＤ４．Ｄ
２の両端の振巾も小になシダイオードＤ１．Ｄ２は非導
通となシＤ１１Ｄ２の等価抵抗は非常に大きくなる。ｋ
赤恭仔ポダイオードＤ、。When a large amplitude signal is supplied to the input terminal, diode D4
．． The amplitude at both ends of D2 is also large.
2 becomes conductive, and the equivalent resistances of Dl and D2 become small. Also, when a signal with a small amplitude is supplied to the input, the diode D4. D
The width at both ends of the diode D1.2 is also small. Since D2 is non-conductive, the equivalent resistance of D11D2 becomes very large. k
Red Kyoko Podiode D.

Ｄ２の両端にダイオードが導通し始める程度の振巾が供
給されると、Ｄｌ、Ｄ２０等価抵抗は、ダイオードＤ、
、Ｄ２の電圧対電流特性による値を示す。このように入
力信号の振巾にょジエンファシス量が変わることになり
、その特性は第２図で表される。When a amplitude to the extent that the diode starts to conduct is supplied to both ends of D2, the equivalent resistance of Dl and D20 becomes the diode D,
, D2 shows the value according to the voltage vs. current characteristics. In this way, the amplitude of the input signal changes the amount of emphasis, and its characteristics are shown in FIG.

しかし上記の回路ではダイオードＤ、、Ｄ２の特性によ
る振巾検出の為、所要のエンファシス特性を得る為には
入力端子には４〜（Ｓ　ＶＰＰ程度のの大振巾の輝度信
号が供給される必要があった。However, in the above circuit, the amplitude is detected by the characteristics of the diodes D, D2, so in order to obtain the required emphasis characteristic, a luminance signal with a large amplitude of about 4 to (SVPP) is supplied to the input terminal. There was a need.

その為、回路の電源電圧の低電圧化へしようとするとダ
イナミックレンジを広ぐとることができない。従って回
路設計が困難であるばかシで々く、非線形強調回路を含
む記録の為の信号処理回路全体をＩＣ化することが困難
であった。Therefore, if an attempt is made to lower the power supply voltage of the circuit, it is not possible to widen the dynamic range. Therefore, the circuit design is difficult and stupid, and it is difficult to integrate the entire recording signal processing circuit including the nonlinear emphasizing circuit into an IC.

〈発明の目的〉 本発明は上述従来例の欠点を除去した非線形強調回路の
提供を目的としている。<Objective of the Invention> An object of the present invention is to provide a nonlinear emphasizing circuit that eliminates the drawbacks of the above-mentioned conventional example.

く実施例の説明〉 第３図は本発明の一実施例の非線形強調回路図である。Description of Examples> FIG. 3 is a nonlinear enhancement circuit diagram of an embodiment of the present invention.

図において第１図と同様の機能を有するものには同じ符
号を付した。３は増幅回路、４は位相反転回路、ｖｌけ
入力端子に供給給される入力信号、ｖｌは増幅回路６の
入力信号、■２　は位相反転回路４の出方信号で回路の
出力信号である。位相反転回路４は増幅回路３の入力信
号ｖ１　　の位相を１８００位相反転した信号ｖ２．を
低出力インピーダンスで出力する。次に第４図を用いて
第３図の回路動作について説明する。第４図で（ａ）は
増幅回路３の入力信号Ｖ４、（ｂ）は位相反転回路４の
出力信号■２、（Ｃ）はコンデンサＣ２とダイオードＤ
、　、Ｄ２の直列回路の両端にかかる信号波形を示して
いる。入力端子１に信号ｖ２が供給されると増幅回路３
の入力端子にはＲ４図（Ｌ）の信号が供給され、位相反
転回路４の出力端子には第４図（１）ｌの信号が出力さ
れる。増幅回路３の電圧利得をｎとすると位相反転回路
４の出力信号ｖ２は、増幅回路３０入力信号Ｖ、の８倍
で１８０゜位相反転された信号となる。次に、逆極性で
並列接続されたダイオードＤＬＩＤ２とコンデンサＣ２
の直列回路の両端に加わる信号は、ｖｌとｖ２の差をと
ることにより（ｎ＋ｉ）　Ｖ、となり、第４図（０）に
示される。また、位相反転回路４の出力インピーダンス
は低い為、第３図の基本構成図は第５図の回路に等測的
に表わされる。このように、逆極性で並列接続されたダ
イオード・Ｄ４．Ｄ２トコンデンサＣ２の直列回路の両
端には、第１図の従来のノンリニアエンファシス回路に
比べて（ｎ＋１）倍の信号が供給されることになシ、ダ
イオードＤ、、Ｄ２の両端の振巾も（ｎ＋１）倍になる
。そこで第１図の従来の回路と同等の特性を得る為の入
力信号ｖ１は、従来の回路に比べて４１にすることがで
きる。第３図で出力端子２は増幅回路３の入力端もしく
は出力端に接続しても同様の性能を有する。In the figure, parts having the same functions as those in FIG. 1 are given the same reference numerals. 3 is an amplifier circuit, 4 is a phase inversion circuit, an input signal supplied to the input terminal of vl, vl is an input signal of the amplifier circuit 6, and 2 is an output signal of the phase inversion circuit 4, which is the output signal of the circuit. . The phase inversion circuit 4 generates a signal v2. which is obtained by inverting the phase of the input signal v1 of the amplifier circuit 3 by 1800 degrees. output with low output impedance. Next, the operation of the circuit shown in FIG. 3 will be explained using FIG. 4. In Figure 4, (a) is the input signal V4 of the amplifier circuit 3, (b) is the output signal ■2 of the phase inversion circuit 4, and (C) is the capacitor C2 and diode D.
, , and shows the signal waveforms applied to both ends of the series circuit of D2. When the signal v2 is supplied to the input terminal 1, the amplifier circuit 3
The signal shown in FIG. 4 (L) is supplied to the input terminal of R4, and the signal shown in FIG. 4 (1) l is outputted to the output terminal of the phase inversion circuit 4. Assuming that the voltage gain of the amplifier circuit 3 is n, the output signal v2 of the phase inversion circuit 4 is a signal whose phase is inverted by 180 degrees and is eight times that of the input signal V of the amplifier circuit 30. Next, diode DLID2 and capacitor C2 are connected in parallel with opposite polarity.
The signal applied to both ends of the series circuit becomes (n+i) V by taking the difference between vl and v2, as shown in FIG. 4(0). Furthermore, since the output impedance of the phase inversion circuit 4 is low, the basic configuration diagram of FIG. 3 is isometrically represented by the circuit of FIG. 5. In this way, the diodes D4. A signal that is (n+1) times as large as that of the conventional nonlinear emphasis circuit shown in Fig. 1 is supplied to both ends of the series circuit of the capacitor C2, and the amplitudes of the diodes D and D2 are also (n+1) times. Therefore, in order to obtain characteristics equivalent to those of the conventional circuit shown in FIG. 1, the input signal v1 can be set to 41, compared to the conventional circuit. In FIG. 3, the output terminal 2 has the same performance even if it is connected to the input terminal or the output terminal of the amplifier circuit 3.

又、本実施例では増幅回路３と位相反転回路４を直列接
続しているが、位相反転回路４はダイオードＤ１．Ｄ２
よシなる非線形回路と、高周波を取シ出すコンデンサＣ
２で構成されるフィルタ回路よりなる直列回路側に設け
てもよい。Further, in this embodiment, the amplifier circuit 3 and the phase inversion circuit 4 are connected in series, but the phase inversion circuit 4 is connected to the diode D1. D2
A good nonlinear circuit and a capacitor C that extracts high frequencies
It may be provided on the side of a series circuit consisting of a filter circuit constituted by 2.

第６図は第３図の回路を更に詳細にした回路図である。FIG. 6 is a circuit diagram showing the circuit of FIG. 3 in further detail.

図において、第３図の回路と同様の機能を有するものＫ
は同じ符号を付した。図でトランジスタ５，６、抵抗７
，９、可変抵抗８は、第３図の増幅回路３及び位相反転
回路４を構成している。なお、次にこの回路の動作を説
明する。入力端子１よシ入力された輝度信号社抵抗Ｒ１
，Ｒ２，コンデンサＣ４で構成される高域強調回路を介
してトランジスタ５のベースに供給される。In the figure, K has the same function as the circuit in Figure 3.
are given the same symbol. In the figure, transistors 5 and 6, and resistor 7
, 9, and the variable resistor 8 constitute the amplifier circuit 3 and phase inversion circuit 4 in FIG. Note that the operation of this circuit will be explained next. Luminance signal resistor R1 input from input terminal 1
, R2, and a capacitor C4.

トランジスタ５、抵抗７、可変抵抗８で構成されるエミ
ッタ接地増幅器で増幅位相反転された輝度信号は、トラ
ンジスタ５のコレクタに出力され、トランジスタ６、抵
抗９で構成されたエミッタホロワを介して出力端子２に
得られる。The luminance signal that has been amplified and phase-inverted by the common emitter amplifier composed of a transistor 5, a resistor 7, and a variable resistor 8 is output to the collector of the transistor 5, and then sent to the output terminal 2 via an emitter follower composed of a transistor 6 and a resistor 9. can be obtained.

そして、輝度信号に含まれた高周波成分の振幅が小さく
ダイオードＤ、　、Ｄ２を導通しない期間は抵抗Ｒ，Ｊ
Ｒ２％　コンデンサＣ１によるバイパスフィルタの特性
によシ高周波は強調されて出力される。また、高周波成
分の振巾が大きくダイオードＤ　、　、Ｄ２を導通させ
る期間は抵抗Ｒ１，Ｒ２、コンデンサＣ７によるバイパ
スフィルタのＲ２に並列１ｃＣ２が付加され高周波の強
調は制限される。また、可変抵抗８を調整することによ
りダイオードＤ１．Ｄ２の導通ポイントを可変とするこ
とが可能となる。従って入力信号のレベルが異なる場合
にも適用できる。During the period when the amplitude of the high frequency component included in the luminance signal is small and the diodes D, , D2 are not conductive, the resistors R, J
R2% Due to the characteristics of the bypass filter formed by capacitor C1, high frequencies are emphasized and output. Furthermore, during the period when the amplitude of the high frequency component is large and the diodes D1, D2, and D2 are conductive, 1cC2 is added in parallel to R2 of the bypass filter consisting of resistors R1, R2 and capacitor C7, and the emphasis on high frequencies is limited. Also, by adjusting the variable resistor 8, the diode D1. It becomes possible to make the conduction point of D2 variable. Therefore, it can be applied even when the input signal levels are different.

尚、本実施例においては非線形回路をダイオード２つを
互いに逆向きに並列接続しているが、非線形整流素子と
しては他にトランジスタのコレクタとベースを短絡或は
コレクタを開放等してダイオードとして用いてもよい。In this example, the nonlinear circuit is made up of two diodes connected in parallel in opposite directions, but the nonlinear rectifier can also be used as a diode by shorting the collector and base of a transistor or opening the collector. It's okay.

又、望まれる非線形特性によってはＦＥＴ等の他の非線
形整流素子を用いてもよい。Further, other nonlinear rectifying elements such as FETs may be used depending on the desired nonlinear characteristics.

〈効果の説明〉 以上説明したように、本発明の非線形強調回路によれば
、従来回路で大入力を供給しなければ得られ々かった所
要のノンリニアエンファシス特性を、かなシ小さい入力
信号でも得ることができる。また増幅器の利得を変える
ことにょ多自由な入力レベルにおいてもＰｆｒ要の特性
が得られる。<Description of Effects> As explained above, according to the nonlinear emphasizing circuit of the present invention, the required nonlinear emphasis characteristic, which could not be obtained without supplying a large input with conventional circuits, can be obtained even with a very small input signal. be able to. Further, by changing the gain of the amplifier, the characteristic required for Pfr can be obtained even at various input levels.

従って従来の回路では困難であった回路電源の低電圧化
、非線形強調回路を含めた周辺回路のＩＣ化が可能とな
った。また、従来回路の上記欠点改善の為電圧対電流特
性の良いショットキーダイオードを用いていた場合には
、シリコンダイオードに替えてＩＣ内にとシ込むことも
可能となる。このような本発明の非線形強調回路はテレ
ビジョン信号の記録の為のプリエンファシス回路を始め
種々の回路への応用が可能である。Therefore, it has become possible to lower the voltage of the circuit power supply and to integrate peripheral circuits including the nonlinear emphasis circuit into ICs, which was difficult with conventional circuits. Further, in the case where a Schottky diode with good voltage-to-current characteristics is used to improve the above-mentioned drawbacks of the conventional circuit, it becomes possible to insert the Schottky diode into the IC instead of the silicon diode. Such a nonlinear emphasizing circuit of the present invention can be applied to various circuits including a pre-emphasis circuit for recording television signals.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は従来の非線形強調回路図、第２図は従動回路の
特性図、第３図は本実施例の基本構成図、第４図（ａｌ
　ｔ　（ｂ）　−（Ｃ）は第３図の動作説明図、Ｍ５図
は第３図の基本構成図の等価構成図、第６図は第３図の
詳細回路図を示す。 １・・・入力端子 ２・・・出力端子 ３・・・増幅器 ４・・・位相反転回路 ５．６・・・トランジスタ ７．９・・・抵抗 ８・・・可変抵抗 Ｒ１，Ｒ２・・・抵抗 ｃｃ　　・・・コンデンサ ２ ＤＤ　　・・・ダイオード １＃２ 出願人　キャノン株式会社 代理人丸島儀−酪７４ ’ｔｌ！Ｉ＋５−岑Fig. 1 is a conventional nonlinear emphasis circuit diagram, Fig. 2 is a characteristic diagram of a driven circuit, Fig. 3 is a basic configuration diagram of this embodiment, and Fig. 4 (al.
t(b)-(C) are operation explanatory diagrams of FIG. 3, FIG. M5 is an equivalent configuration diagram of the basic configuration diagram of FIG. 3, and FIG. 6 is a detailed circuit diagram of FIG. 3. 1... Input terminal 2... Output terminal 3... Amplifier 4... Phase inversion circuit 5.6... Transistor 7.9... Resistor 8... Variable resistors R1, R2... Resistance cc...Capacitor 2 DD...Diode 1#2 Applicant: Canon Co., Ltd. Agent: Gi Marushima-Kyoku 74'tl! I+5-岑

Claims (2)

【特許請求の範囲】[Claims] （１）　　入力信号が供給される高域強調回路と、前記
強調回路の出力を増幅器と、前記強調回路の出力のうち
高周波成分を取）出すフィルタ回路と、互いに逆向きに
接続された少くとも２つの非線形整１５１Ｉ、素子よシ
なる非線形回路と、位相を反転する位相反転回路とを有
し。 前記フィルタ回路と前記非線形回路よシ成る直列回路を
前記増幅器と並列に接続し、前記直列回路若しくは前記
増幅器に前記位相反転回路を設けたことを特徴とする非
線形強調回路０(1) At least a high-frequency emphasis circuit to which an input signal is supplied, an amplifier for the output of the emphasis circuit, and a filter circuit for extracting high frequency components from the output of the emphasis circuit, which are connected in opposite directions to each other. It has two nonlinear controllers 151I, a nonlinear circuit consisting of an element, and a phase inversion circuit that inverts the phase. A nonlinear emphasizing circuit 0 characterized in that a series circuit consisting of the filter circuit and the nonlinear circuit is connected in parallel with the amplifier, and the series circuit or the amplifier is provided with the phase inversion circuit. （２）　　前記増幅器の利得を可変としたことを特徴と
する特許請求の範囲９１項記載の非線形強調回路。(2) The nonlinear emphasizing circuit according to claim 91, characterized in that the gain of the amplifier is variable.