JPH0416286Y2 - - Google Patents
Info
- Publication number
- JPH0416286Y2 JPH0416286Y2 JP1984139508U JP13950884U JPH0416286Y2 JP H0416286 Y2 JPH0416286 Y2 JP H0416286Y2 JP 1984139508 U JP1984139508 U JP 1984139508U JP 13950884 U JP13950884 U JP 13950884U JP H0416286 Y2 JPH0416286 Y2 JP H0416286Y2
- Authority
- JP
- Japan
- Prior art keywords
- transistor
- circuit
- recording amplifier
- output signal
- recording
- 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
- 239000003990 capacitor Substances 0.000 claims description 15
- 238000009499 grossing Methods 0.000 claims description 11
- 230000007257 malfunction Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 231100000989 no adverse effect Toxicity 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
Landscapes
- Signal Processing Not Specific To The Method Of Recording And Reproducing (AREA)
- Control Of Amplification And Gain Control (AREA)
Description
【考案の詳細な説明】
(イ) 産業上の利用分野
本考案は、テープレコーダに用いられるALC
（自動レベル制御）回路を備える録音増幅器に関
するもので、特に前記ALC回路が録音バイアス
回路により悪影響を受けるのを防止した録音増幅
器に関するものである。[Detailed explanation of the invention] (a) Industrial application field This invention is an ALC used in tape recorders.
The present invention relates to a recording amplifier equipped with an automatic level control (automatic level control) circuit, and particularly relates to a recording amplifier in which the ALC circuit is prevented from being adversely affected by a recording bias circuit.
(ロ) 従来の技術
入力信号レベルの大小に依らず、増幅器の出力
端に生じる録音されるべき信号のレベルを一定に
するALC回路を備える録音増幅器が、特開昭58
−178615号公報に見られる如く公知である。ま
た、磁気テープへの録音に際し、磁気ヘツドに交
流バイアス信号を供給する技術も、昭和53年６月
20日付で発行された「テープ・レコーダーとその
活きた使い方」第154頁に見られる如く、従来公
知である。第２図は、前記ALC回路及び録音バ
イアス回路ほ備える録音増幅器を示すもので、１
は録音増幅器、２は該録音増幅器１の出力信号レ
ベルを検出し、該録音増幅器２の入力信号を減衰
させる為のALC回路、３は前記録音増幅器１の
出力信号に応じた録音を行う為の磁気ヘツド、４
は該磁気ヘツド３に交流バイアス信号を供給する
録音バイアス回路、及び５は該録音バイアス回路
４の出力信号が録音増幅器１の側に漏れるのを防
止する為のトラツプ回路である。(b) Prior Art A recording amplifier equipped with an ALC circuit that keeps the level of the signal to be recorded produced at the output end of the amplifier constant regardless of the magnitude of the input signal level was disclosed in Japanese Patent Laid-Open No. 58
It is well known as seen in Japanese Patent No.-178615. Additionally, technology for supplying an AC bias signal to the magnetic head when recording onto magnetic tape was introduced in June 1973.
As can be seen on page 154 of ``Tape Recorders and Their Effective Use'' published on the 20th, this is well known. Figure 2 shows a recording amplifier including the ALC circuit and recording bias circuit.
2 is a recording amplifier; 2 is an ALC circuit for detecting the output signal level of the recording amplifier 1 and attenuating the input signal of the recording amplifier 2; 3 is an ALC circuit for performing recording according to the output signal of the recording amplifier 1; magnetic head, 4
5 is a recording bias circuit for supplying an AC bias signal to the magnetic head 3, and 5 is a trap circuit for preventing the output signal of the recording bias circuit 4 from leaking to the recording amplifier 1 side.
しかして、入力端子６に印加される入力信号
は、録音増幅器１で増幅され該録音増幅器１の出
力端に導出されるが、前記録音増幅器１の出力信
号レベルが所定値に達するとALC回路２が動作
して前記入力信号の減衰が行なわれるので、前記
録音増幅器１の出力信号レベルは一定値に保たれ
る。そして、前記録音増幅器１の出力信号と録音
バイアス回路４の出力交流バイアス信号とが磁気
ヘツド３に印加され、録音が達成される。その
時、録音バイアス回路４の出力交流バイアス信号
が録音増幅器１の出力側に漏れるのを防止する
為、前記出力交流バイアス信号周波数を中心周波
数とするトラツプ回路５を設け、ALC回路２が
前記出力交流バイアス信号により誤動作するのを
防止している。通常、交流バイアス信号周波数と
しては、信号周波数の４〜５倍の50〜200KHzが
用いられるので、トラツプ回路５の中心周波数も
50〜200KHzに設定される。 Thus, the input signal applied to the input terminal 6 is amplified by the recording amplifier 1 and delivered to the output terminal of the recording amplifier 1, but when the output signal level of the recording amplifier 1 reaches a predetermined value, the ALC circuit 2 operates to attenuate the input signal, so the output signal level of the recording amplifier 1 is maintained at a constant value. Then, the output signal of the recording amplifier 1 and the output AC bias signal of the recording bias circuit 4 are applied to the magnetic head 3 to accomplish recording. At this time, in order to prevent the output AC bias signal of the recording bias circuit 4 from leaking to the output side of the recording amplifier 1, a trap circuit 5 whose center frequency is the frequency of the output AC bias signal is provided. This prevents malfunctions caused by bias signals. Usually, the AC bias signal frequency is 50 to 200 KHz, which is 4 to 5 times the signal frequency, so the center frequency of the trap circuit 5 is also
Set to 50~200KHz.
(ハ) 考案が解決しようとする問題点
正常動作状態においては、録音増幅器１の出力
インピーダンスが十分に小である為、トラツプ回
路５が十分に効力を発揮し、録音バイアス回路４
の出力信号が遮断され、ALC回路２に悪影響を
及ぼすことは無い。しかしながら、電源投入直後
等の過渡時には、録音増幅器１の出力インピーダ
ンスが十分に小とならず、前記録音バイアス回路
４の出力信号が漏れ、ALC回路２の平滑コンデ
ンサが異常に充電され、録音増幅器１の入力信号
を必要以上に減衰してしまうという欠点があつ
た。(c) Problems to be solved by the invention Under normal operating conditions, the output impedance of the recording amplifier 1 is sufficiently small, so the trap circuit 5 is fully effective and the recording bias circuit 4
The output signal is cut off, and there is no adverse effect on the ALC circuit 2. However, during a transient period such as immediately after the power is turned on, the output impedance of the recording amplifier 1 does not become sufficiently small, the output signal of the recording bias circuit 4 leaks, the smoothing capacitor of the ALC circuit 2 is abnormally charged, and the recording amplifier 1 The disadvantage is that the input signal is attenuated more than necessary.
(ニ) 問題点を解決するための手段
本考案は、上述の点に鑑み成されたもので、電
源投入後一定期間ALC回路の比較部の動作を停
止する為の停止部を備えた点を特徴とする。(d) Means for solving the problem The present invention was developed in view of the above points, and has the feature that it is equipped with a stop section for stopping the operation of the comparison section of the ALC circuit for a certain period of time after power is turned on. Features.
(ホ) 作用
本考案に依れば、電源投入時にALC回路を不
動作にし、所定時間経過後前記ALC回路を動作
状態に復帰させるので、ALC回路の平滑コンデ
ンサが異常に充電されることが無い。(e) Effect According to the present invention, the ALC circuit is made inactive when the power is turned on, and the ALC circuit is returned to the operating state after a predetermined period of time has elapsed, so that the smoothing capacitor of the ALC circuit is not charged abnormally. .
(ヘ) 実施例
第１図は、本考案の一実施例を示す回路図で、
７は入力端子８に印加される入力信号を増幅する
録音増幅器、９は差動接続された一対のトランジ
スタ１０及び１１から成る比較部１２と、該比較
部１２の出力信号を整流する整流トランジスタ１
３と、該整流トランジスタ１３の出力信号を平滑
する抵抗１４及びコンデンサ１５から成る平滑回
路１６と、該平滑回路１６の出力信号に応じて動
作する駆動トランジスタ１７及び減衰トランジス
タ１８とから成るALC回路、１９は電源ライン
にコレクタ・エミツタ路が挿入されたトランジス
タ２０と、該トランジスタ２０のベースに接続さ
れたコンデンサ２１とから成るリツプルフイル
タ、２２は差動接続された一対のトランジスタ２
３及び２４から成り、一方のトランジスタ２３の
ベースが前記コンデンサ２１の一端に、他方のト
ランジスタ２４のベースが基準電位点に接続され
た停止回路、及び２５は該停止回路２２の他方の
トランジスタ２４のコレクタ電流に応じてオン
し、ALC回路９の比較的１２の電流源トランジ
スタ２６をオンにする為のダイオード接続された
トランジスタである。(F) Embodiment Figure 1 is a circuit diagram showing an embodiment of the present invention.
7 is a recording amplifier that amplifies the input signal applied to the input terminal 8; 9 is a comparator section 12 consisting of a pair of differentially connected transistors 10 and 11; and a rectifier transistor 1 that rectifies the output signal of the comparator section 12 .
3, a smoothing circuit 16 consisting of a resistor 14 and a capacitor 15 that smooth the output signal of the rectifying transistor 13, and an ALC circuit consisting of a drive transistor 17 and an attenuation transistor 18 that operate according to the output signal of the smoothing circuit 16 ; 19 is a ripple filter consisting of a transistor 20 whose collector-emitter path is inserted into the power supply line, and a capacitor 21 connected to the base of the transistor 20; 22 is a pair of differentially connected transistors 2;
3 and 24, the base of one transistor 23 is connected to one end of the capacitor 21, the base of the other transistor 24 is connected to the reference potential point, and 25 is the stop circuit of the other transistor 24 of the stop circuit 22. This is a diode-connected transistor that turns on in response to the collector current and turns on the comparatively 12 current source transistors 26 of the ALC circuit 9 .
電源（＋Vcc）を投入すると、停止回路２２の
他方のトランジスタ２４のベースが略直ちに基準
電圧になる。そけに対し、リツプルフイルタ１９
のコンデンサ２１の存在の為に、一方のトランジ
スタ２３のベース電圧は低く、短絡回路２２は、
一方のトランジスタ２３がオン、他方のトランジ
スタ２４がオフになる。その結果、ダイオード接
続されたトランジスタ２５がオフになり、ALC
回路９の比較部１２の電流源トランジスタ２６が
オフになつて、前記比較部１２が動作を開始しな
い。比較部１２が動作しないと、整流トランジス
タ１３も導通せず、平滑コンデンサ１５が充電さ
れないので、減衰トランジスタ１８が減衰動作を
行なわず、ALC動作が行なわれない。 When the power (+V cc ) is turned on, the base of the other transistor 24 of the stop circuit 22 becomes the reference voltage almost immediately. Ripple filter 19
Due to the presence of the capacitor 21, the base voltage of one transistor 23 is low, and the short circuit 22 is
One transistor 23 is turned on and the other transistor 24 is turned off. As a result, diode-connected transistor 25 is turned off and the ALC
The current source transistor 26 of the comparator 12 of the circuit 9 is turned off, and the comparator 12 does not start operating. If the comparator 12 does not operate, the rectifier transistor 13 will not conduct, and the smoothing capacitor 15 will not be charged, so the attenuation transistor 18 will not perform the attenuation operation and no ALC operation will be performed.
時間が経過し、リツプルフイルタ１９のコンデ
ンサ２１の充電が進み、該コンデンサ２１の端子
電圧が、短絡回路２２の他方のトランジスタ２４
のベースに印加される基準電圧を越えると、前記
短絡回路２２の一方のトランジスタ２３がオフ、
他方のトランジスタ２４がオンになり、ダイオー
ド接続されたトランジスタ２５もオンになる。そ
の為、比較部１２の電流源トランジスタ２６が正
常に導通し、前記比較部１２の比較動作が開始さ
れる。 As time passes, charging of the capacitor 21 of the ripple filter 19 progresses, and the terminal voltage of the capacitor 21 changes to the other transistor 24 of the short circuit 22.
When the reference voltage applied to the base of the transistor 23 is exceeded, one transistor 23 of the short circuit 22 is turned off;
The other transistor 24 is turned on, and the diode-connected transistor 25 is also turned on. Therefore, the current source transistor 26 of the comparator 12 becomes normally conductive, and the comparison operation of the comparator 12 is started.
比較部１２の他方のトランジスタ１１のベース
には基準電圧が印加され、一方のトランジスタ１
０のベースには録音増幅器７の出力信号が印加さ
れるので、前記録音増幅器７の出力信号が前記基
準電圧よりも小の間、一方のトランジスタ１０が
オフ、他方のトランジスタ１１がオンとなり、
ALC動作は行なわれない。録音増幅器７の出力
信号が大となつて前記基準電圧を越えると、一方
のトランジスタ１０がオンとなり、差電圧に応じ
たコレクタ電流が流れる。その為、整流トランジ
スタ１３が導通し、平滑回路１６のコンデンサ１
５の充電が行なわれ、駆動トランジスタ１７及び
減衰トランジスタ１８が導通してALC動作が行
なわれる。従つて、録音増幅器７の出力信号は一
定に保たれ、出力端子２７に一定レベルの被録音
信号が発生する。 A reference voltage is applied to the base of the other transistor 11 of the comparator 12 , and one transistor 1
Since the output signal of the recording amplifier 7 is applied to the base of the recording amplifier 7, one transistor 10 is turned off and the other transistor 11 is turned on while the output signal of the recording amplifier 7 is smaller than the reference voltage.
No ALC operation is performed. When the output signal of the recording amplifier 7 becomes large and exceeds the reference voltage, one of the transistors 10 is turned on, and a collector current flows according to the difference voltage. Therefore, the rectifier transistor 13 becomes conductive, and the capacitor 1 of the smoothing circuit 16
5 charging is performed, the drive transistor 17 and the attenuation transistor 18 are turned on, and an ALC operation is performed. Therefore, the output signal of the recording amplifier 7 is kept constant, and a recorded signal of a constant level is generated at the output terminal 27.
短絡回路２２は、電源投入後所定時間経過した
後出力信号を発生しなくなり、その時間は、リツ
プルフイルタ１９のコンデンサ２１の充電時定数
と、前記短絡回路２２の他方のトランジスタ２４
のベースに印加される基準電圧とに応じて決ま
る。その為、録音増幅器７が安定してその出力イ
ンピーダンスが十分小となつた後に出力信号の発
生が行なわれる様、前記短絡回路２２の前記時間
を設定することにより、ALC回路９の誤動作が
防止出来る。 The short circuit 22 stops generating an output signal after a predetermined period of time has elapsed after the power is turned on, and this time is determined by the charging time constant of the capacitor 21 of the ripple filter 19 and the other transistor 24 of the short circuit 22.
The reference voltage applied to the base of the Therefore, malfunction of the ALC circuit 9 can be prevented by setting the time of the short circuit 22 so that the output signal is generated after the recording amplifier 7 is stabilized and its output impedance becomes sufficiently small. .
(ト) 考案の効果
以上述べた如く、本考案に依れば、電源投入直
後に交流バイアス信号により平滑回路のコンデン
サが充電されてALC回路が作動する、という誤
動作が防止出来る。また本考案に依れば、短絡回
路を設けるだけで前記誤動作が防止出来、前記短
絡回路の出力信号は比較部の電流源トランジスタ
のバイアス電流となるので、集積回路化が容易で
あり、構成簡単にして安価な録音増幅器が提供出
来る。(g) Effects of the invention As described above, according to the invention, it is possible to prevent the malfunction in which the capacitor of the smoothing circuit is charged by the AC bias signal immediately after power is turned on, and the ALC circuit is activated. Furthermore, according to the present invention, the above malfunction can be prevented simply by providing a short circuit, and the output signal of the short circuit becomes the bias current of the current source transistor of the comparison section, so it is easy to integrate the circuit and the configuration is simple. Therefore, an inexpensive recording amplifier can be provided.
第１図は、本考案の一実施例を示す回路図、及
び第２図は従来のALC回路付録音増幅器を示す
回路ブロツク図である。
主な図番の説明、７……録音増幅器、９……
ALC回路、１２……比較部、１６……平滑回路、
１９……リツプルフイルタ、２２……短絡回路。
FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit block diagram showing a conventional recording amplifier with an ALC circuit. Explanation of main drawing numbers, 7...Recording amplifier, 9 ...
ALC circuit, 12 ...comparison section, 16 ...smoothing circuit,
19...Ripple filter, 22 ...Short circuit.
Claims (1)
音増幅器の出力信号レベルを検出する比較部と、
該比較部の出力信号を整流平滑する平滑部と、該
平滑部の出力信号に応じて前記録音増幅器の入力
信号を減衰する減衰部と、コンデンサを含み電源
ラインに挿入されるリツプルフイルタと、ベース
が所定電位点に接続され、そのコレクタから前記
比較部に所定の動作電流を供給する定電流トラン
ジスタと、エミツタが前記定電流トランジスタの
エミツタに共通接続されるとともに、ベースが前
記リツプルフイルタを構成するコンデンサに接続
された停止用トランジスタとから成り、電源投入
後一定期間前記停止用トランジスタをオンさせる
ことにより前記定電流トランジスタをオフさせ、
前記比較部の動作を停止させて、前記平滑部のコ
ンデンサが録音バイアス回路により充電されるの
を防止したことを特徴とする録音増幅器。 In a recording amplifier equipped with an ALC circuit, a comparison section detecting an output signal level of the recording amplifier;
a smoothing section that rectifies and smoothes the output signal of the comparison section; an attenuation section that attenuates the input signal of the recording amplifier according to the output signal of the smoothing section; and a ripple filter that includes a capacitor and is inserted into a power supply line. a constant current transistor whose base is connected to a predetermined potential point and which supplies a predetermined operating current from its collector to the comparison section; and whose emitter is commonly connected to the emitter of the constant current transistor, and whose base connects the ripple filter. and a stop transistor connected to a constituting capacitor, and turns off the constant current transistor by turning on the stop transistor for a certain period of time after power is turned on,
A recording amplifier characterized in that the operation of the comparison section is stopped to prevent a capacitor of the smoothing section from being charged by a recording bias circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1984139508U JPH0416286Y2 (en) | 1984-09-14 | 1984-09-14 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1984139508U JPH0416286Y2 (en) | 1984-09-14 | 1984-09-14 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6155254U JPS6155254U (en) | 1986-04-14 |
| JPH0416286Y2 true JPH0416286Y2 (en) | 1992-04-13 |
Family
ID=30697885
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1984139508U Expired JPH0416286Y2 (en) | 1984-09-14 | 1984-09-14 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0416286Y2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2556844B2 (en) * | 1986-10-07 | 1996-11-27 | ロ−ム株式会社 | Automatic level control amplifier |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5515653B2 (en) * | 1975-07-22 | 1980-04-25 |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5929378Y2 (en) * | 1978-07-13 | 1984-08-23 | 三洋電機株式会社 | ALC circuit |
-
1984
- 1984-09-14 JP JP1984139508U patent/JPH0416286Y2/ja not_active Expired
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5515653B2 (en) * | 1975-07-22 | 1980-04-25 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6155254U (en) | 1986-04-14 |
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