JPS6113708A - Electronic tuner - Google Patents
Electronic tunerInfo
- Publication number
- JPS6113708A JPS6113708A JP13421984A JP13421984A JPS6113708A JP S6113708 A JPS6113708 A JP S6113708A JP 13421984 A JP13421984 A JP 13421984A JP 13421984 A JP13421984 A JP 13421984A JP S6113708 A JPS6113708 A JP S6113708A
- Authority
- JP
- Japan
- Prior art keywords
- terminal
- output
- circuit
- vhf
- switching
- 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
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J5/00—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner
- H03J5/24—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection
- H03J5/242—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection used exclusively for band selection
- H03J5/244—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection used exclusively for band selection using electronic means
Landscapes
- Channel Selection Circuits, Automatic Tuning Circuits (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明はテレビジョンやビデオテープレコーダに使用さ
れる電子チューナに関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to electronic tuners used in televisions and video tape recorders.
従来例の構成とその問題点
従来例を第１図に示しておシ、図においてＲ４〜ＲＳは
抵抗、Ｃ１〜Ｃ４５はコンデンサ、Ｄ、〜Ｄ、はダイオ
ード、Ｌ、〜Ｌ６はコイル、Ｌ８は可変インダクタンス
、Ｔｒ４ ’ Ｔｒ２はトランジスタである。The structure of the conventional example and its problems The conventional example is shown in Fig. 1. In the figure, R4 to RS are resistors, C1 to C45 are capacitors, D and ~D are diodes, L and ~L6 are coils, and L8 is a variable inductance, and Tr4' Tr2 is a transistor.
従来の回路においては、周波薮変換回路で混合されたＩ
Ｆ倍信号、ＶＨＦローチャンネル、ハイチャンネル、Ｕ
ＨＦ各バンドとも、共通のＩＰ同調回路によって取出さ
れている。この場合、混合段の動作条件は、ＶＨＦロー
チャンネル、・・イチャンネル、ＵＨＦ各バンド受信時
によって、−少しづつ異なる特性を示すことが多い。す
なわち、ＩＦ出力インピーダンスが各バンド間す変動し
てしまう。この原因はＶＨＦローチャンネル、ハイチャ
ンネル間で局部発振注入電圧の違いに′よるところが大
きく、またＵＨＦ受信時、ＶＨＦ混合段は増幅として動
作（局部発振注入電圧が零となる）するためと考えられ
る。In the conventional circuit, the I mixed in the frequency conversion circuit is
F times signal, VHF low channel, high channel, U
Each HF band is extracted by a common IP tuning circuit. In this case, the operating conditions of the mixing stage often exhibit slightly different characteristics depending on when receiving the VHF low channel, ichannel, and UHF bands. That is, the IF output impedance varies between each band. This is largely due to the difference in local oscillation injection voltage between the VHF low channel and high channel, and is also thought to be because the VHF mixing stage operates as an amplifier (the local oscillation injection voltage becomes zero) during UHF reception. .
このように各バンド間の出力特性は、本来同一であるべ
きにもかかわらず、このような変化を示すことは、総合
ビデオｆ特性上杆ましくない。Even though the output characteristics between each band should be the same, it is not appropriate for the overall video f characteristics to exhibit such a change.
発明の目的
本発明はこのような現状に鑑みなされたもので、バンド
間の出力特性の均一化を図ることを目的とするものであ
る。OBJECT OF THE INVENTION The present invention was made in view of the current situation, and an object thereof is to make the output characteristics uniform between bands.
発明の構成
この目的を達成するために本発明は、ＩＦ出力回路にス
イッチングダイオードを挿入接続し、ＶＩＦハイチャン
ネル、ローチャンネル受信切換え時に、ＩＦ出力回路の
出力インピーダンスを切換えるように構成したものであ
る。Structure of the Invention To achieve this object, the present invention is configured such that a switching diode is inserted and connected to the IF output circuit, and the output impedance of the IF output circuit is switched when switching between VIF high channel and low channel reception. .
実施例の説明
第２図に本発明の一実施例による電子チューナを示して
おシ、第１図と同一箇所については同一記号を付してい
る。図において、Ｒ４〜Ｒアは抵抗、Ｃ１６はコンデン
サ＋Ｄ４ はスイッチングダイオードである。DESCRIPTION OF THE EMBODIMENTS FIG. 2 shows an electronic tuner according to an embodiment of the present invention, and the same parts as in FIG. 1 are given the same symbols. In the figure, R4 to R are resistors, C16 is a capacitor, and D4 is a switching diode.
この回路において、ＶＨＦノ・イチャンネル受信時は、
端子１に十Ｂ電圧が印加され、端子２け接地され、各同
調回路のスイッチングダイオードＤ１〜Ｄ３は短絡状態
となり、各同調回路はノ・イバンド受信状態となる。ま
だ、これと同時に、スイッチングダイオードＤ４も短絡
され、従来と同じく所望のＩＦ出力特性が得られる。In this circuit, when receiving VHF channel,
A voltage of 10B is applied to terminal 1, terminal 2 is grounded, switching diodes D1 to D3 of each tuning circuit are short-circuited, and each tuning circuit is in a no-band reception state. However, at the same time, the switching diode D4 is also short-circuited, and the desired IF output characteristics can be obtained as in the conventional case.
次に、ＶＨＦローチャンネル受信時は、端子１に十Ｂ電
圧、端子２には端子１よシも８ｖ以上高い電圧（−１−
３０Ｖ）が印加され、各スイッチングダイオードＤ１〜
Ｄ５がオープン状態となり、各同調回路はローバンド受
信状態に切換えられる。本発明の回路においては、これ
と同時にスイッチングダイオードＤ４もオープンとなり
、 これによりＩＦ出力同調用の可変インダクタンスに
対して抵抗Ｒ４が直列に挿入接続されることとなる。こ
の抵抗Ｒ４の値を数オーム−数１０オームに選定するこ
とにより、ＩＦ同調回路がＶＨＦローチャンネル受信時
のみ、抵抗Ｒ４の直列ダンピング効果でダンピングされ
ることとなる。Next, when receiving the VHF low channel, terminal 1 has a voltage of 10B, and terminal 2 has a voltage that is 8V or more higher than terminal 1 (-1-
30V) is applied to each switching diode D1~
D5 becomes open, and each tuning circuit is switched to a low band receiving state. In the circuit of the present invention, the switching diode D4 is also opened at the same time, so that the resistor R4 is inserted and connected in series with the variable inductance for IF output tuning. By selecting the value of this resistor R4 to be several ohms to several tens of ohms, the IF tuning circuit is damped by the series damping effect of the resistor R4 only when receiving the VHF low channel.
第３図Ａ、Ｂに従来例と本発明とのＩＦ出力特性を示し
ており、従来例のものにおいては、第３図人のようにＶ
ＨＦローチャンネル受信時にＩＦ出力インピーダンスが
高くなり、出力帯域幅が狭くなる傾向があるが、本発明
では、第３図ＢのようにＶＨＦハイチャンネルを基準と
して、ＶＨＦローチャンネルの出力特性をダンピングす
ることで、両者をほぼ均一な特性とすることができる。FIGS. 3A and 3B show the IF output characteristics of the conventional example and the present invention. In the conventional example, as shown in FIG.
When receiving the HF low channel, the IF output impedance tends to increase and the output bandwidth tends to narrow; however, in the present invention, the output characteristics of the VHF low channel are damped using the VHF high channel as a reference as shown in FIG. 3B. By doing so, both can be made to have substantially uniform characteristics.
発明の効果
以上のように本発明によれば、受信バンド切換え時にお
ける出力特性を均一なものＫすることができる。Effects of the Invention As described above, according to the present invention, it is possible to make the output characteristics uniform when switching reception bands.
第１図は従来の電子チューナを示す回路図、第２図は本
発明の一実施例による電子チューナを示す回路図、第３
図Ａ、Ｂは従来と本発明のチ一ナにおけるＩＦ出力特性
を比較して示す特性図である。
Ｄ４・・・・・・スイッチングダイオード、Ｒ４・・・
・・・抵抗。
代理人の氏名 弁理士 中 尾 敏 男 はが１名第１
図
第２図FIG. 1 is a circuit diagram showing a conventional electronic tuner, FIG. 2 is a circuit diagram showing an electronic tuner according to an embodiment of the present invention, and FIG.
Figures A and B are characteristic diagrams showing a comparison of the IF output characteristics of the conventional and the present invention china. D4...Switching diode, R4...
···resistance. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure 2
Claims (1)
ＶＨＦハイチャンネル、ローチャンネル受信切換え時に
、ＩＦ出力回路の出力インピーダンスを切換えるように
構成した電子チューナ。Insert and connect a switching diode to the IF output circuit,
An electronic tuner configured to switch the output impedance of the IF output circuit when switching between VHF high channel and low channel reception.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13421984A JPS6113708A (en) | 1984-06-28 | 1984-06-28 | Electronic tuner |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13421984A JPS6113708A (en) | 1984-06-28 | 1984-06-28 | Electronic tuner |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6113708A true JPS6113708A (en) | 1986-01-22 |
Family
ID=15123204
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13421984A Pending JPS6113708A (en) | 1984-06-28 | 1984-06-28 | Electronic tuner |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6113708A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6486757B2 (en) * | 1999-12-16 | 2002-11-26 | Alps Electric Co., Ltd. | Double-tuned circuit of tuner featuring restrained degradation of selectivity |
-
1984
- 1984-06-28 JP JP13421984A patent/JPS6113708A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6486757B2 (en) * | 1999-12-16 | 2002-11-26 | Alps Electric Co., Ltd. | Double-tuned circuit of tuner featuring restrained degradation of selectivity |
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