JPS6348236B2 - - Google Patents
Info
- Publication number
- JPS6348236B2 JPS6348236B2 JP55089223A JP8922380A JPS6348236B2 JP S6348236 B2 JPS6348236 B2 JP S6348236B2 JP 55089223 A JP55089223 A JP 55089223A JP 8922380 A JP8922380 A JP 8922380A JP S6348236 B2 JPS6348236 B2 JP S6348236B2
- Authority
- JP
- Japan
- Prior art keywords
- lpf
- recording
- color
- color signal
- trap
- 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.)
- Expired
Links
- 238000010586 diagram Methods 0.000 description 10
- 108010063955 thrombin receptor peptide (42-47) Proteins 0.000 description 4
- 230000006866 deterioration Effects 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/79—Processing of colour television signals in connection with recording
- H04N9/80—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
- H04N9/82—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback the individual colour picture signal components being recorded simultaneously only
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
Description
【発明の詳細な説明】
本発明は家庭用VTRの信号処理回路に関する
ものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a signal processing circuit for a home VTR.
記録ビデオ信号の帯域制限をするための低域通
過フイルタ（以下記録LPFと記す。）とFM復調
器で復調された復調ビデオ信号からFMキヤリア
またはその高調波を除去するための低域通過フイ
ルタ（以下再生LPFと記す。）を兼用した家庭用
VTRのビデオ信号処理回路において、従来は、
カラーモアレ、リンギング、解像度等の画質の良
否を決める重要な特性のすべてを許容範囲内にお
さめることが困難であつた。以下この問題点を詳
しく説明する。 A low-pass filter (hereinafter referred to as recording LPF) for band-limiting the recording video signal and a low-pass filter (hereinafter referred to as recording LPF) for removing the FM carrier or its harmonics from the demodulated video signal demodulated by the FM demodulator. (hereinafter referred to as recycled LPF) for home use
In the video signal processing circuit of a VTR, conventionally,
It has been difficult to keep all important characteristics that determine image quality, such as color moiré, ringing, and resolution, within acceptable ranges. This problem will be explained in detail below.
第１図に記録LPFとして要求される周波数振
幅特性を第２図に再生LPFとして要求される周
波数振幅特性の定性的な図を示す。 FIG. 1 shows a qualitative diagram of the frequency and amplitude characteristics required for a recording LPF, and FIG. 2 shows a qualitative diagram of the frequency and amplitude characteristics required for a reproduction LPF.
第１図の記録LPFの特徴について説明する。
その特徴は第１にカラー副搬送周波数scにトラ
ツプを有していることと、第２に3MHz付近の減
衰量を後述する再生LPFに比べ大きくとつてい
ることである。これは色の変化するところではカ
ラー信号の帯域がsc±500KHzに広がるため、
3MHz付近の減衰量が小さいと、残留カラー信号
でFM変調することになりその下側波が低域変換
カラー信号帯域に落ち込み、再生時カラーモアレ
を生じる。これを抑圧するため、ある程度の減衰
量をとる必要がある。 The features of the recording LPF shown in FIG. 1 will be explained.
Its characteristics are, firstly, that it has a trap at the color subcarrier frequency sc, and secondly, that the amount of attenuation around 3MHz is larger than that of the reproducing LPF, which will be described later. This is because the color signal band expands to sc±500KHz where the color changes.
If the amount of attenuation near 3MHz is small, FM modulation is performed with the residual color signal, and its lower side wave falls into the low frequency conversion color signal band, causing color moiré during playback. In order to suppress this, it is necessary to provide a certain amount of attenuation.
次に第２図の再生LPFの特徴について述べる。 Next, we will discuss the characteristics of the regenerating LPF shown in Figure 2.
復調ビデオ信号にはカラー信号成分はないので
周波数scにトラツプを入れる必要は特にない。
4MHz付近にトラツプを入れるのは、FMキヤリ
アの中心周波数が約4MHzであり、そのキヤリア
リークを除去するためである。以上述べたように
記録LPFと再生LPFとでは要求される特性が異
なる。したがつて記録LPFと再生LPFを兼用す
る場合には、兼用しない場合に比べ、以下に述べ
るような問題点を生じる。 Since there is no color signal component in the demodulated video signal, there is no particular need to insert a trap at the frequency sc.
The trap is placed near 4MHz because the center frequency of the FM carrier is approximately 4MHz, and the purpose is to remove carrier leakage. As described above, the required characteristics are different between the recording LPF and the reproduction LPF. Therefore, when the recording LPF and the reproducing LPF are used together, the following problems occur compared to when they are not used together.
まず兼用LPFの特性を記録LPFの特性に近づ
けた場合、高域での信号レベルが落ち解像度劣化
を生じる。トラツプ周波数が再生LPFトラツプ
周波数より低いため2.5〜3.0MHz付近の遅延時間
が大きく生じ、リンギング等が発生しやすい。 First, if the characteristics of the dual-purpose LPF are brought close to those of the recording LPF, the signal level in the high frequency range will drop and resolution will deteriorate. Since the trap frequency is lower than the reproduction LPF trap frequency, a large delay time occurs around 2.5 to 3.0 MHz, and ringing etc. are likely to occur.
逆に兼用LPFの特性を再生LPFの特性に近づ
けた場合、記録カラー信号の除去が充分ではなく
なり、前述したようにカラーモアレを生じやすく
なる。 On the other hand, if the characteristics of the dual-purpose LPF are brought close to those of the reproduction LPF, the recording color signal will not be removed sufficiently, and color moiré will likely occur as described above.
以上述べた理由から現在、製品化されている
VTRのほとんどは、LPFを記録と再生回路に別
別に設けており、コストダウン、基板の小型化を
阻む要因となつている。またLPFを兼用する場
合以上述べたような問題から充分な画質を得るこ
とは難しい。 For the reasons mentioned above, it is currently being commercialized.
Most VTRs have separate LPFs for recording and playback circuits, which is a factor that prevents cost reductions and miniaturization of circuit boards. Furthermore, when the LPF is also used, it is difficult to obtain sufficient image quality due to the problems described above.
本発明の目的は上記した従来技術の欠点をなく
し、画質劣化を招くことなく、記録と再生の
LPFを兼用し、コストダウン基板面積の縮小化
を可能にする信号処理回路を提供することにあ
る。 The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to enable recording and playback without deterioration of image quality.
The object of the present invention is to provide a signal processing circuit that can also be used as an LPF to reduce costs and reduce the board area.
本発明は記録カラービデオ信号と、FM復調器
出力とを切り替えるスイツチを設けて、記録と再
生のLPFを兼用し、該LPFと、FM復調器との間
にカラー信号除去用トラツプを配置し該カラー信
号除去用トラツプのＱを独立に設計できるように
する。 The present invention provides a switch for switching between a recorded color video signal and an FM demodulator output, which serves as both a recording and reproducing LPF, and a trap for removing color signals is placed between the LPF and the FM demodulator. To enable independent design of the Q of a color signal removal trap.
このようなシステムをとることにより該LPF
は再生ビデオ信号回路の特性にあわせ、記録ビデ
オ信号回路の特性は該カラー信号除去トラツプの
Ｑを適当に設計することにより得るようにすれば
画質劣化を招くことなくLPFを兼用できる。 By adopting such a system, the LPF
If the characteristics of the recording video signal circuit are matched to the characteristics of the reproduction video signal circuit and the Q of the color signal removal trap is appropriately designed, it can be used as an LPF without deteriorating the image quality.
第３図に本発明のブロツク構成図を示し概略説
明する。ただし説明に不要なブロツクは省略して
ある。 FIG. 3 shows a block diagram of the present invention and will be briefly described. However, blocks unnecessary for explanation are omitted.
まず信号の流れを簡単に説明する。 First, the signal flow will be briefly explained.
記録時には入力端子１より入力された記録カラ
ービデオ信号がスイツチ４により選択され、記録
再生兼用LPF５に供給され帯域制限を受けカラ
ー信号除去トラツプ６でカラー信号が除去され、
FM変調器７を介して出力端子８より出力され、
記録アンプ、ビデオヘツドを介してビデオテープ
に記録される。再生時は、入力端子２より入力さ
れた再生FM信号がFM復調器３で、ビデオ信号
に復調され、スイツチ４で選択され、兼用LPF
５に供給される。ここでFMキヤリア成分が除去
され、再生ビデオ信号処理回路９でノイズ抑圧等
の信号処理が施され、出力端子１０より出力され
る。 During recording, the recorded color video signal input from the input terminal 1 is selected by the switch 4, is supplied to the LPF 5 for both recording and reproduction, is subjected to band restriction, and the color signal is removed by the color signal removal trap 6.
It is output from the output terminal 8 via the FM modulator 7,
It is recorded on videotape via a recording amplifier and video head. During playback, the playback FM signal input from the input terminal 2 is demodulated into a video signal by the FM demodulator 3, selected by the switch 4, and sent to the dual-purpose LPF.
5. Here, the FM carrier component is removed, signal processing such as noise suppression is performed in the reproduced video signal processing circuit 9, and the signal is outputted from the output terminal 10.
ここで兼用LPF５の特性を第２図に示す特性
に設計すれば再生回路の特性は、記録、再生
LPFを独立に設けていた従来の特性と同じであ
り、再生回路において画質劣化を招くことはな
い。 If the dual-purpose LPF 5 is designed to have the characteristics shown in Figure 2, the characteristics of the playback circuit will change between recording and playback.
The characteristics are the same as in the conventional system where the LPF was provided independently, and there is no deterioration in image quality in the reproduction circuit.
記録時は兼用LPF５とカラー信号除去トラツ
プ６の総合特性が第１図の特性になるようにカラ
ー信号除去トラツプ６のＱを設計することによ
り、記録時に発生するカラーモアレを抑圧するこ
とができる。 By designing the Q of the color signal removal trap 6 so that the overall characteristics of the dual-purpose LPF 5 and the color signal removal trap 6 become the characteristics shown in FIG. 1 during recording, color moiré occurring during recording can be suppressed.
第４図にカラー信号除去トラツプの一実施例を
示す。抵抗１２、インダクタ１３、コンデンサ１
４の値をそれぞれＲ，Ｌ，Ｇとすると、入力端子
１１から出力端子１５までの伝達関数Ｔ（Ｓ）は
Ｔ（Ｓ）＝S2＋１／LC／S2＋Ｒ／ＬＳ＋１／LC
と表わせ、トラツプ周波数R、共振の鋭さＱは下
式のようになる。 FIG. 4 shows an embodiment of the color signal removal trap. Resistor 12, inductor 13, capacitor 1
4 are respectively R, L, and G, the transfer function T(S) from input terminal 11 to output terminal 15 can be expressed as T(S)=S 2 +1/LC/S 2 +R/LS+1/LC, The trap frequency R and resonance sharpness Q are as shown in the following equation.
したがつてＲを変えることによりＱを変えるこ
とができる。第５図に第２図の回路の定性的振幅
特性をＲをパラメータとして示す。第５図中イ，
ロ，ハはＲの大、中、小に相当する。したがつて
第３図における兼用LPF５とカラ信号除去トラ
ツプ６との定性的な総合振幅特性は第６図のよう
になる。第６図中イ，ロ，ハはＲの大、中、小に
相当するのは同様である。 Therefore, by changing R, Q can be changed. FIG. 5 shows the qualitative amplitude characteristics of the circuit of FIG. 2 with R as a parameter. A in Figure 5,
B and C correspond to large, medium, and small R. Therefore, the qualitative overall amplitude characteristics of the dual-purpose LPF 5 and the color signal removal trap 6 in FIG. 3 are as shown in FIG. Similarly, letters A, B, and C in FIG. 6 correspond to large, medium, and small R.
このようにカラー信号除去特性は、カラー信号
除去トラツプのＱを変えることによりおこなうの
で、再生ビデオ信号処理回路の特性に影響を与え
ない。 As described above, since the color signal removal characteristics are achieved by changing the Q of the color signal removal trap, the characteristics of the reproduced video signal processing circuit are not affected.
以上述べたシステムを採用することにより、解
像度、カラーモアレ、リンギング等の画質劣化を
招くことなく輝度信号の記録、再生LPFを兼用
することができ、コストダウン基板の縮小化を実
現できる。 By adopting the system described above, the LPF can be used for recording and reproducing luminance signals without causing deterioration in image quality such as resolution, color moiré, ringing, etc., and it is possible to reduce costs and downsize the board.
たとえば記録再生のLPFは位相補償フイルタ
とともに１組120円程度であり、カラー信号除去
トラツプが30円程度であることから約90円のコス
トダウンが可能である。 For example, an LPF for recording and reproduction costs about 120 yen per set together with a phase compensation filter, and a color signal removal trap costs about 30 yen, so it is possible to reduce the cost by about 90 yen.
第１図は記録ビデオ信号処理回路の周波数特性
図、第２図は再生LPFの周波数特性図、第３図
は本発明の一実施例を示すブロツク構成図、第４
図はカラー信号除去フイルタの一具体例を示す回
路図、第５図はカラー信号除去フイルタの特性の
一例を示す周波数特性図、第６図は本発明システ
ムの記録ビデオ信号処理回路の周波数特性図であ
る。
４…スイツチ、３…低域通過フイルタ、６…カ
ラー信号除去フイルタ、７…FM変調器。
Fig. 1 is a frequency characteristic diagram of the recording video signal processing circuit, Fig. 2 is a frequency characteristic diagram of the reproduction LPF, Fig. 3 is a block configuration diagram showing an embodiment of the present invention, and Fig. 4 is a frequency characteristic diagram of the recording video signal processing circuit.
Figure 5 is a circuit diagram showing a specific example of a color signal removal filter, Figure 5 is a frequency characteristic diagram showing an example of the characteristics of the color signal removal filter, and Figure 6 is a frequency characteristic diagram of the recording video signal processing circuit of the system of the present invention. It is. 4...Switch, 3...Low pass filter, 6...Color signal removal filter, 7...FM modulator.
Claims (1)
て、記録カラービデオ信号と、FM復調器出力と
を切り替えるスイツチと、該スイツチ出力が供給
される低域通過フイルタを具備し、該低域通過フ
イルタとFM変調器との間にカラー信号除去フイ
ルタを配置したことを特徴とする信号処理回路。1. A recording/reproducing processing circuit of a magnetic recording/reproducing device is equipped with a switch that switches between a recorded color video signal and an FM demodulator output, and a low-pass filter to which the output of the switch is supplied, and the low-pass filter and the FM A signal processing circuit characterized in that a color signal removal filter is arranged between a modulator and a color signal removal filter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8922380A JPS5715588A (en) | 1980-07-02 | 1980-07-02 | Signal processing circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8922380A JPS5715588A (en) | 1980-07-02 | 1980-07-02 | Signal processing circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5715588A JPS5715588A (en) | 1982-01-26 |
| JPS6348236B2 true JPS6348236B2 (en) | 1988-09-28 |
Family
ID=13964725
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8922380A Granted JPS5715588A (en) | 1980-07-02 | 1980-07-02 | Signal processing circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5715588A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0732487B2 (en) * | 1982-02-17 | 1995-04-10 | 株式会社日立製作所 | Recording circuit for video and audio signals |
-
1980
- 1980-07-02 JP JP8922380A patent/JPS5715588A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5715588A (en) | 1982-01-26 |
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