JP4370763B2

JP4370763B2 - Acoustic equipment and other equipment with cooling fan motor voltage control circuit

Info

Publication number: JP4370763B2
Application number: JP2002260369A
Authority: JP
Inventors: 正幸三澤
Original assignee: Funai Electric Co Ltd
Current assignee: Funai Electric Co Ltd
Priority date: 2002-09-05
Filing date: 2002-09-05
Publication date: 2009-11-25
Anticipated expiration: 2022-09-05
Also published as: JP2004100493A

Description

【０００１】
【発明の属する技術分野】
本発明は冷却ファンを駆動するための冷却ファンモータ電圧制御回路を備えた音響機器及びその他の機器に関する。
【０００２】
【従来の技術】
近年、小型、大容量化されたハードディスクドライブをビィデオ信号記録用として用いたレコーダが普及しつつある。しかし、ハードディスクドライブは発熱量が多いため、レコーダ本体に冷却ファンを設けなければならない。ところが、音声信号の再生を伴うレコーダにあっては冷却ファンの風切り音が使用者にとって騒音となる。特に、音楽信号の再生にあっては極めて大きな障害となる。そこで、定常回転では定格電圧以下の低い電圧を供給し風切り音の発生をなくし、起動時には高い電圧を供給し起動が円滑になされるようにしている。このような風切り音発生の防止策は、前記レコーダに限らず各種の機器にも考慮されている。
【０００３】
そのために、例えば、特開平６−１８９５８６号公報（第１の従来技術）に記載されているように、プリンターのような機器ではアイドル中は比較的に冷却する必要性が少ないので冷却ファンを低速運転させて風切り音の発生をなくし、稼動時には高速運転させるようにしている。併せて、温度センサーを用いて冷却の必要性を検知し冷却ファンモータへの供給電圧を制御するという技術が提案されている。
【０００４】
また、例えば、特開平６−３３５２８５号公報（第２の従来技術）に記載されているように、冷却ファンの起動時には起動に必要な高い電圧を供給し、その後は少なくとも定常回転に必要な電圧まで下げ、円滑な起動と低騒音化を図っている。その制御として、電源回路にコンデンサ、抵抗からなる所定の時定数を持つ積分回路を設け、冷却ファンの起動時のみ高い電圧を供給するようにした技術が提案されている。
【０００５】
更に、例えば、特開平８−１２６３６１号公報（第３の従来例）に記載されているように、電源投入時には確実な起動のための電圧を供給し、その後の定常運転時には風切り音が発生しない電圧まで低下させ、確実な起動と低騒音化を図っている。その制御として、電源投入時にトリガーされる例えば単安定マルチバイブレータからなるパルス発生回路を用いて起動時にのみ冷却ファンモータに高い電圧を供給し、その後は低い電圧を供給する技術が提案されている。
【０００６】
【発明が解決しようとする課題】
前記第１の従来技術では、温度センサーによって周囲温度を検知し、冷却ファンの高速運転、低速運転を行うもので、風切り音対策を優先する例えば音響機器においては採用できない。即ち、この従来例では、音響機器の使用中に何らかの原因により温度が上昇してしまうと冷却ファンが高速回転して突然、風切り音が発生してしまうという問題点がある。また、起動を円滑に行うことは考慮されておらず、しかも、温度センサーを設けるためにコスト高となる等の問題点がある。
【０００７】
また、前記第２の従来技術では、前記第１の従来技術の問題点である風切り音対策と起動対策については改善されている。しかし、冷却フアンモータには起動特性にばらつきがあるため、積分回路の設定時定数は前記ばらつきを全て吸収できるに十分な大きなものとしなければならない。そのため、このような冷却ファンを適用した機器は、電源投入後にしばらく高速回転がなされ、早期に風切り音をなくすことができないという問題点がある。即ち、この従来例では、機器の使用開始の最初の期間に風切り音がどうしても入ってしまうという問題点がある。
【０００８】
更に、前記第３の従来例では、前述と同様に風切り音対策と起動対策については改善されているが、高い電圧の供給には一定のパルス幅を有するパルスを発生するパルス発生回路を用いているため、前記第２の従来技術と同様に冷却ファンモータの起動特性のばらつくを考慮した十分に大きなパルス幅を必要とする。そのため、やはり電源投入後にしばらく高速回転がなされてしまい、早期に風切り音を無くすことができないという問題点がある。即ち、この従来例でも、機器の使用開始の最初の期間に風切り音がどうしても入ってしまうという問題点がある。
【０００９】
本発明は、上記従来技術の有する課題を解決し、音響機器及びその他の機器の使用者に与える風切り音の悪影響を確実になくし、しかも低コストで構成した冷却ファンモータ電圧制御回路を備えた音響機器及びその他の機器を提供することを目的とする。
【００１０】
【課題を解決するための手段】
上記目的を達成するため、請求項１に係る発明は、ハードディスクドライブ、電源回路、回路基板等の発熱源を冷却するための冷却ファンを有する音響機器において、前記冷却ファンを駆動する冷却ファンモータに直流電圧を供給する直流電源と、この直流電源と前記冷却ファンモータとの間に直列接続されて前記冷却ファンを風切り音が発生しない低速の所定回転速度で回転させるための所定直流電圧に前記直流電源の直流電圧を低減して前記冷却ファンモータに供給する定電圧素子および電源スイッチと、前記冷却ファンモータと直列に接続されて当該冷却ファンモータに流れる電流を自体に発生する電圧降下の値によって検出する電流検出用抵抗と、前記電流検出用抵抗で発生する電圧降下の値を検出してスイッチング動作する検出用トランジスタと、前記定電圧素子と並列に接続されて前記検出用トランジスタのスイッチング動作によってスイッチング制御されるバイパス用トランジスタとを有し、前記電源スイッチのオン時に、前記冷却ファンモータに前記冷却ファンを起動させるための負荷に応じた定常時よりも大きな電流が流れ、この冷却ファンモータに流れる電流により前記電流検出用抵抗に発生する大きな電圧降下の値を検出して前記検出用トランジスタがオフからオンにスイッチング動作し、このスイッチング動作により前記バイパス用トランジスタが定常時のオフからオンに転換されて前記定電圧素子を短絡することにより、前記直流電源からオン状態の前記パイパス用トランジスタを介して前記冷却ファンモータに直流電圧が供給され、前記冷却ファンの起動が完了して負荷が減少するのに伴って前記冷却ファンモータに流れる電流が急激に減少することにより、前記電流検出用抵抗に発生する電圧降下の値が低下して前記検出用トランジスタがオンからオフにスイッチング動作し、このスイッチング動作により前記バイパス用トランジスタがオフに転換されて前記定電圧素子の短絡が解除され、前記冷却ファンモータに前記定電圧素子を介して前記所定直流電圧が供給されることより前記冷却ファンが前記所定回転速度で回転するように制御される冷却ファンモータ電圧制御回路を備えた音響機器である。
【００１１】
一方、請求項２に係る発明は、電源回路、回路基板等の発熱源を冷却するための冷却ファンを有する機器において、前記冷却ファンを駆動する冷却ファンモータに直流電圧を供給する直流電源と、前記直流電源と前記冷却ファンモータとの間に直列接続されて前記冷却ファンを風切り音が発生しない低速の所定回転速度で回転させるための所定直流電圧に前記直流電源の直流電圧を低減して前記冷却ファンモータに供給する定電圧素子および電源スイッチと、前記冷却ファンモータと直列に接続されて当該冷却ファンモータに流れる電流を自体に発生する電圧降下の値によって検出する電流検出用抵抗と、前記電流検出用抵抗で発生する電圧降下の値を検出してスイッチング動作する検出用スイッチング素子と、前記定電圧素子と並列接続されて前記検出用スイッチング素子のスイッチング動作によってスイッチング制御されるバイパス用スイッチング素子とを有し、前記電源スイッチのオン時に、前記冷却ファンモータに前記冷却ファンを起動させるための負荷に応じた定常時よりも大きな電流が流れ、この冷却ファンモータに流れる電流により前記電流検出用抵抗に発生する大きな値の電圧降下を検出して前記検出用スイッチング素子がオフからオンにスイッチング動作し、このスイッチング動作により前記バイパス用スイッチング素子が定常時のオフからオンに転換されて前記定電圧素子を短絡することにより、前記直流電源からオン状態の前記パイパス用スイッチング素子を介して前記冷却ファンモータに直流電圧が供給され、前記冷却ファンの起動が完了して負荷が減少するのに伴って前記冷却ファンモータに流れる電流が急激に減少することにより、前記電流検出用抵抗に発生する電圧降下の値が低下して前記検出用スイッチング素子がオンからオフにスイッチング動作し、このスイッチング動作により前記バイパス用スイッチング素子がオフに転換されて前記定電圧素子の短絡が解除され、前記冷却ファンモータに前記定電圧素子を介して前記所定直流電圧が供給されることより前記冷却ファンが前記所定回転速度で回転するように制御される冷却ファンモータ電圧制御回路を備えた機器である。
【００１２】
また、請求項３に係る発明は、電源回路、回路基板等の発熱源を冷却するための冷却ファンを有する機器において、前記冷却ファンを駆動する冷却ファンモータに直流電圧を供給する直流電源と、前記直流電源と前記冷却ファンモータとの間に直列接続されて前記直流電源の直流電圧をツェナー電圧に低減することにより前記冷却ファンを風切り音が発生しない低速の所定回転速度で回転させる所定直流電圧を前記冷却ファンモータに供給するツェナーダイオードおよび電源スイッチと、前記冷却ファンモータと直列に接続されて当該冷却ファンモータに流れる電流を自体に発生する電圧降下の値によって検出する電流検出用抵抗と、前記電流検出用抵抗で発生する電圧降下の値を検出してスイッチング動作する検出用トランジスタと、前記ツェナーダイオードと並列に接続されて前記検出用トランジスタのスイッチング動作によってスイッチング制御されるバイパス用トランジスタとを有し、前記電源スイッチのオン時に、前記冷却ファンモータに前記冷却ファンを起動させるための負荷に応じた定常時よりも大きな電流が流れ、この冷却ファンモータに流れる電流により前記電流検出用抵抗に発生する大きな値の電圧降下を検出して前記検出用トランジスタがオフからオンにスイッチング動作し、このスイッチング動作により前記バイパス用トランジスタが定常時のオフからオンに転換されて前記ツェナーダイオードを短絡することにより、前記直流電源からオン状態の前記パイパス用トランジスタを介して前記冷却ファンモータに直流電圧が供給され、前記冷却ファンの起動が完了して負荷が減少するのに伴って前記冷却ファンモータに流れる電流が急激に減少することにより、前記電流検出用抵抗に発生する電圧降下の値が低下して前記検出用トランジスタがオンからオフにスイッチング動作し、このスイッチング動作により前記バイパス用トランジスタがオフに転換されて前記ツェナーダイオードの短絡が解除され、前記冷却ファンモータに前記ツェナーダイオードのツェナー電圧により設定された前記所定直流電圧が供給されることより前記冷却ファンが前記所定回転速度で回転するように制御される冷却ファンモータ電圧制御回路を備えた機器である。
【００１３】
請求項３に係る発明において、前記電流検出用抵抗および前記冷却ファンモータの接続点と前記検出用トランジスタのベースとの間にバイアス抵抗が接続され、前記電流検出用抵抗が、その抵抗値が可変設定可能な可変型抵抗からなることが好ましい。
【００１４】
図１は、本発明の実施の形態の一例における冷却ファンモータ電圧制御回路のブロック図である。１は冷却ファンモータであり、例えばレコーダのような音響機器本体（図示せず）に設けられている。１は直流電源、３は電源スイッチである。４は冷却ファンモータ１と直列に接続されたツェナーダイオードからなる電圧制限素子、１１は同じく冷却ファンモータ１と直列に接続された電流検出用抵抗であり、この実施の形態では抵抗値を可変設定可能な可変型抵抗を用いた場合を例示してある。冷却ファンモータ１は直流電源の電圧が電圧制限素子４によって低減されて供給されるようになっている。この低減された電圧は冷却ファンモータ１がそのファンで風切り音を生じない程度で回転するように設定されている。６は電圧制限素子４と並列に接続されたバイパス手段を構成するバイパス用トランジスタであり、ＰＮＰ型トランジスタからなり、そのエミッタが電圧制限素子４を構成するツェナーダイオードのカソード側に接続され、そのコレクタがツェナーダイオードのアノード側に接続され、そのベース電位の低下によってオフからオンに転換してバイパス回路を形成するようになっている。７はバイパス用トランジスタのエミッタとベース間に接続されたバイアス抵抗である。
【００１５】
８は電流検出用抵抗１１で発生する電圧降下の値を検出するための検出手段を構成する検出用トランジスタであり、ＮＰＮ型トランジスタからなり、そのエミッタが直流電源２のマイナス側に接続され、そのベースが直流電源２のマイナス側に対し電流検出用抵抗１１を介した側に接続され、そのコレクタが抵抗９を介してバイパス用トランジスタのベースに接続されている。１０は検出用トランジスタ８のコレクタに接続されたバイアス抵抗であり、電流検出用抵抗１１に所定値以上の電流が流れるとこれに対応した電圧降下の電圧値によって検出用トランジスタ８がオフからオンに転換するようになっている。そして、検出用トランジスタ９のオン動作によりバイパス用トランジスタ６がオンに転換するようになっている。
【００１６】
次に、本発明の実施の形態による冷却ファンモータ電圧設定回路の動作について説明する。
【００１７】
機器の使用開始に伴って電源スイッチ３が閉成され冷却ファンモータ１に直流電圧が供給される。この直流電圧の供給開始時点では、冷却ファンモータ１には定常状態より大きな電流が流れて回転を開始する。そのため、電流検出用抵抗１１にも大きな電流が流れてそこでの電圧降下の値が大きくなる。この大きな電圧降下の値によって検出用トランジスタ８のベース電位がプラス方向に大きく変位し、定常状態ではオフになっている検出用トランジスタ８をオンに転換する。そして、バイパス用トランジスタ６は、そのベース電位がマイナス方向に変位し、定常状態ではオフになっている状態からオンに転換しバイパス回路を形成する。このバイパス回路の形成によって冷却ファンモータ１には、電圧制限素子４によって制限されない高い直流電圧が供給される。
【００１８】
従って、冷却ファンモータ１は高トルクを発生し直ちに高速回転に向かって回転する。回転が十分になると冷却フエンモータ１は負荷が少なくなり流れる電流も急激に少なくなる。電流が少なくなると電流検出用抵抗１１での電圧降下の値が小さくなり、検出用トランジスタ８がオンからオフに転換する。このオフへの転換により、バイパス用トランジスタ６は再びオフに転換されバイパス回路が形成されなくなる。そのため、冷却ファンモータ１に供給される電圧は電圧制限素子４によって低減されたファンが風切り音を発生しない値となる。
【００１９】
ここで、起動時にバイパス回路を形成して冷却ファンモータ１に高い電圧を供給する期間は、検出用トランジスタ８のオン、オフの転換のタイミングを予め設定しておくことにより達成する。この実施の形態では、検出用トランジスタ８のオン、オフの転換のタイミングを電流検出用抵抗１１の抵抗値を可変することにより微調整できる。従って、冷却ファンモータ１の起動に必要な最小限の期間が任意に設定可能になり、風切り音の影響を確実に無くすことができる。また、多量、多種生産にあっては、電圧制御回路の基板を共通にして規格の異なる冷却ファンモータ１を採用しても、最適状態に設定できるので、コストを低減できる効果がある。
【００２０】
本発明の実施の形態の一例によれば、機器の使用の開始にあたり電源スイッチ３を閉成した時点では、冷却ファンモータ１に大きな電流が流れる。この状態は電流検出用抵抗１１での電圧降下を検出用トランジスタ８で直接的に検出することができる。そして、バイパス用トランジスタ６をオンとしてバイパス回路を形成して冷却ファンモータ１に高い電圧を供給し起動を短期間で達成させる。冷却ファンモータ１は起動が達成されると負荷が少なくなって電流が急激に低減するので今度は検出用トランジスタ８がオフとなり、バイパス用トランジスタ８をオフとする。このオフへの転換によってバイパス回路が形成されなくなり、冷却ファンモータ１には電圧制限素子４で低減された電圧が供給されるようになり風切り音が発生せず冷却効果のある程度の回転で作動する。このようにして、冷却ファンモータをすばやく起動させ、機器本体の実質的な使用の段階では風切り音の発生がないようにできる。特に、音声信号を扱う音響機器にあってはその効果は大きい。
【００２１】
次に、図２において本発明の実施の形態の他の例について説明するが、前述した図１における実施の形態の一例と同一部分は同一符号を付し、その説明を省略する。
【００２２】
この他の例では、冷却ファンモータ１と直列に、固有の抵抗値を有する固体型抵抗を電流検出用抵抗５として直列に接続されている。そして、その両端に検出手段を形成する検出用トランジスタ８のエミッタとベースが接続されている。
【００２３】
このような本発明の実施の形態の他の例によれば、実施の形態の一例で示した可変型抵抗を電流検出用抵抗１１として用いた場合のように検出用トランジスタ８のオン、オフの転換のタイミングを微調整することができないが、電流検出用抵抗５として所望の抵抗値を有するものを適宜選択して用いれば、冷却ファンモータ１の起動に必要な最小限の期間が設定可能である。
【００２４】
本発明は、その実施の態様の一例及び他の例において電圧制限素子４にツェナーダイオードを用いているが、これに限定されることなくダイオード、抵抗等を用いてもよい。
【００２５】
【発明の効果】
上述したように、本発明の請求項１によれば、冷却ファンモータと直列に接続した電流検出用抵抗において冷却ファンモータに流れる電流変化を検出トランジスタにより直接的に検出できるため、冷却ファンモータに起動に必要な最小限の期間だけ高電圧を供給して起動を完了させ、冷却ファンから生ずる風切り音の影響を実質的に無した音響機器を提供できる効果がある。また、その構成も検出用トランジスタ、バイパス用トランジスタ等を用いるだけでよいため低コストで目的を達成できる効果がある。
【００２６】
また、本発明の請求項２によれば、冷却ファンモータと直列に接続した電流検出用抵抗において冷却ファンモータに流れる電流変化を検出手段により直接的に検出できるため、冷却ファンモータに起動に必要な最小限の期間だけ高電圧を供給して起動を完了させ、冷却ファンから生ずる風切り音の影響を実質的に無した機器を提供できる効果がある。
【００２７】
更に、本発明の請求項３によれば、冷却ファンモータと直列に接続した電流検出用抵抗において冷却ファンモータに流れる電流変化を検出用トランジスタにより直接的に検出できるため、冷却ファンモータに起動に必要な最小限の期間だけ高電圧を供給して起動を完了させ、冷却ファンから生ずる風切り音の影響を実質的になくした機器を提供できる効果がある。また、その構成も検出用トランジスタ、バイパス用トランジスタ等を用いるだけでよいため低コストで目的を達成できる効果がある。
【００２８】
更に、本発明の請求項３によれば、冷却ファンモータと直列に接続した電流検出用抵抗にその値が可変設定な抵抗を用いているため、検出トランジスタ又は検出手段の検出状態を微調整して確実な起動と風切り音の悪影響を排除できる効果がある。
【図面の簡単な説明】
【図１】本発明の実施の形態の一例を示すブロック図である。
【図２】本発明の実施の形態の他の例を示すブロック図である。
【符号の説明】
１冷却ファンモータ
４電圧制限素子
５電流検出用抵抗
６バイパス用トランジスタ
８検出用トランジスタ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an acoustic device including a cooling fan motor voltage control circuit for driving a cooling fan and other devices.
[0002]
[Prior art]
In recent years, recorders using a small-sized and large-capacity hard disk drive for recording video signals are becoming widespread. However, since the hard disk drive generates a large amount of heat, a cooling fan must be provided in the recorder body. However, in the recorder accompanied by the reproduction of the audio signal, the wind noise of the cooling fan becomes noise for the user. In particular, playback of music signals is an extremely serious obstacle. Therefore, in steady rotation, a low voltage equal to or lower than the rated voltage is supplied to eliminate the generation of wind noise, and a high voltage is supplied during start-up to ensure smooth start-up. Such measures for preventing wind noise are considered not only for the recorder but also for various devices.
[0003]
Therefore, for example, as described in Japanese Patent Laid-Open No. 6-189586 (first prior art), a device such as a printer has a relatively low need for cooling during idling, so the cooling fan is operated at a low speed. It is operated to eliminate wind noise and to operate at high speed during operation. In addition, a technique has been proposed in which the necessity of cooling is detected using a temperature sensor and the supply voltage to the cooling fan motor is controlled.
[0004]
For example, as described in Japanese Patent Application Laid-Open No. 6-335285 (second prior art), a high voltage required for starting a cooling fan is supplied when starting the cooling fan, and then a voltage required for at least steady rotation thereafter. To achieve smooth start-up and low noise. As a control for this, a technique has been proposed in which an integration circuit having a predetermined time constant including a capacitor and a resistor is provided in a power supply circuit so that a high voltage is supplied only when the cooling fan is started.
[0005]
Further, for example, as described in Japanese Patent Application Laid-Open No. 8-126361 (third conventional example), a voltage for reliable start-up is supplied when the power is turned on, and no wind noise is generated during the subsequent steady operation. The voltage is lowered to ensure reliable start-up and low noise. As a control for this, a technique has been proposed in which a high voltage is supplied to the cooling fan motor only at the start-up using a pulse generation circuit composed of, for example, a monostable multivibrator that is triggered when the power is turned on, and then a low voltage is supplied.
[0006]
[Problems to be solved by the invention]
In the first prior art, the ambient temperature is detected by a temperature sensor and the cooling fan is operated at a high speed and a low speed, and cannot be adopted in, for example, an audio device that prioritizes measures against wind noise. That is, in this conventional example, if the temperature rises for some reason during use of the acoustic device, there is a problem that the cooling fan rotates at high speed and a wind noise is suddenly generated. In addition, smooth start-up is not taken into account, and there are problems such as high cost due to the provision of the temperature sensor.
[0007]
In the second prior art, wind noise countermeasures and start-up countermeasures, which are problems of the first prior art, are improved. However, since the cooling fan motor has variations in starting characteristics, the setting time constant of the integration circuit must be large enough to absorb all the variations. For this reason, a device to which such a cooling fan is applied has a problem in that it is rotated at a high speed for a while after the power is turned on, and wind noise cannot be eliminated at an early stage. That is, in this conventional example, there is a problem that a wind noise is inevitably generated in the first period of starting use of the device.
[0008]
Further, in the third conventional example, the measures against wind noise and the start-up measures are improved in the same manner as described above, but a pulse generation circuit that generates a pulse having a constant pulse width is used for supplying a high voltage. Therefore, as in the second prior art, a sufficiently large pulse width is required in consideration of variations in the starting characteristics of the cooling fan motor. For this reason, there is still a problem that high-speed rotation is performed for a while after the power is turned on, and wind noise cannot be eliminated at an early stage. That is, even in this conventional example, there is a problem that a wind noise is inevitably generated in the first period of starting use of the device.
[0009]
The present invention solves the above-described problems of the prior art, reliably eliminates the adverse effects of wind noise given to users of acoustic equipment and other equipment, and is equipped with a cooling fan motor voltage control circuit configured at low cost. The purpose is to provide equipment and other equipment.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is directed to a cooling fan motor that drives a cooling fan in an acoustic device having a cooling fan for cooling a heat source such as a hard disk drive, a power supply circuit, and a circuit board. A direct current power source for supplying a direct current voltage, and a direct current voltage that is connected in series between the direct current power source and the cooling fan motor to rotate the cooling fan at a predetermined low rotational speed without generating wind noise. A constant voltage element and a power switch for reducing the direct current voltage of the power supply to supply the cooling fan motor, and a voltage drop value that is connected in series with the cooling fan motor and generates a current flowing through the cooling fan motor. A current detection resistor to detect and a detection operation that performs switching operation by detecting a value of a voltage drop generated in the current detection resistor. A bypass transistor connected in parallel with the constant voltage element and controlled to be switched by a switching operation of the detection transistor, and the cooling fan motor is activated when the power switch is turned on. A larger current flows than in a steady state according to the load to cause the current to flow, and the current flowing through the cooling fan motor detects a value of a large voltage drop generated in the current detection resistor to turn the detection transistor from off to on . The switching fan operates to switch the bypass transistor from OFF to ON in a steady state and short-circuit the constant voltage element, so that the cooling fan is connected from the DC power supply to the ON state via the bypass transistor. DC voltage is supplied to the motor, and the cooling fan By current flowing movement is completed with in the load is reduced to the cooling fan motor is rapidly decreased, the detection transistor value of the voltage drop across the said current detecting resistor is decreased is turned on switching operation off from the bypass transistor by the switching operation is canceled short-circuit of the constant voltage element is converted to off, the predetermined DC voltage via said constant voltage element to the cooling fan motor is supplied Accordingly, the audio device includes a cooling fan motor voltage control circuit that is controlled so that the cooling fan rotates at the predetermined rotation speed.
[0011]
On the other hand, the invention according to claim 2 is a device having a cooling fan for cooling a heat source such as a power supply circuit, a circuit board, etc., and a DC power supply for supplying a DC voltage to a cooling fan motor for driving the cooling fan; The DC voltage of the DC power supply is reduced to a predetermined DC voltage that is connected in series between the DC power supply and the cooling fan motor to rotate the cooling fan at a low predetermined rotation speed that does not generate wind noise. A constant voltage element and a power switch to be supplied to the cooling fan motor; a current detection resistor connected in series with the cooling fan motor to detect a current flowing through the cooling fan motor by a value of a voltage drop generated in itself; A switching element for detection that performs switching operation by detecting a value of a voltage drop generated in a current detection resistor, and is connected in parallel with the constant voltage element. And a bypass switching element that is controlled by a switching operation of the detection switching element. When the power switch is turned on, the cooling fan motor starts from a steady state according to a load for starting the cooling fan. Large current flows, and a large voltage drop generated in the current detection resistor is detected by the current flowing through the cooling fan motor, and the switching element for detection is switched from OFF to ON. By switching the bypass switching element from OFF in the normal state to ON and short-circuiting the constant voltage element, a DC voltage is supplied from the DC power source to the cooling fan motor through the bypass switching element in the ON state. , The cooling fan starts up and the load decreases Wherein when a current flowing to the cooling fan motor rapidly decreases, the current generated in the detection resistor voltage drop value is reduced the detecting switching element is a switching operation from ON to OFF with in that, By this switching operation, the bypass switching element is turned off, the short circuit of the constant voltage element is released, and the cooling fan motor is supplied with the predetermined DC voltage via the constant voltage element. Is a device provided with a cooling fan motor voltage control circuit controlled to rotate at the predetermined rotational speed.
[0012]
According to a third aspect of the present invention, in a device having a cooling fan for cooling a heat source such as a power supply circuit and a circuit board, a direct-current power source that supplies a direct-current voltage to a cooling fan motor that drives the cooling fan; A predetermined DC voltage that is connected in series between the DC power supply and the cooling fan motor to rotate the cooling fan at a low predetermined rotation speed without generating wind noise by reducing the DC voltage of the DC power supply to a Zener voltage. A zener diode and a power switch that supply the cooling fan motor to each other, a current detection resistor that is connected in series with the cooling fan motor and detects a current flowing through the cooling fan motor based on a value of a voltage drop generated in itself, A detection transistor that performs a switching operation by detecting a value of a voltage drop generated in the current detection resistor; and A bypass transistor connected in parallel with the diode diode and controlled to be switched by a switching operation of the detection transistor, and when the power switch is turned on, the load is used to start the cooling fan in the cooling fan motor A larger current flows in response to the steady state, and the current flowing through the cooling fan motor detects a large voltage drop generated in the current detection resistor, and the detection transistor performs switching operation from OFF to ON. A DC voltage is supplied from the DC power source to the cooling fan motor via the bypass transistor which is turned on by switching the bypass transistor from OFF to ON by switching operation and short-circuiting the Zener diode. The cooling fan is activated By current flowing through the cooling fan motor complete to load with to decrease rapidly decreases, the current off the detection transistor value of the voltage drop across the detection resistor is reduced from ON In this switching operation, the bypass transistor is turned off, the short circuit of the Zener diode is released, and the predetermined DC voltage set by the Zener voltage of the Zener diode is supplied to the cooling fan motor. Thus, the apparatus includes a cooling fan motor voltage control circuit that is controlled so that the cooling fan rotates at the predetermined rotation speed.
[0013]
In the invention according to claim 3, wherein the bias resistor between the connection point of the current detection resistor and the cooling fan motor and the base of the detecting transistor is connected to the current detection resistor, the resistance value is variable Preferably, the variable resistor is settable .
[0014]
FIG. 1 is a block diagram of a cooling fan motor voltage control circuit in an example of an embodiment of the present invention. Reference numeral 1 denotes a cooling fan motor, which is provided in an audio equipment body (not shown) such as a recorder. Reference numeral 1 is a DC power source, and 3 is a power switch. 4 the cooling fan motor 1 and made of zener diode connected in series the voltage limiting element, 11 Ri current detection resistor der which is also connected to the cooling fan motor 1 in series, the variable resistance value in this embodiment A case where a variable resistor that can be set is used is illustrated. The cooling fan motor 1 is supplied with the voltage of the DC power supply reduced by the voltage limiting element 4. The reduced voltage is set so that the cooling fan motor 1 rotates to such an extent that no wind noise is generated by the fan. Reference numeral 6 denotes a bypass transistor which constitutes a bypass means connected in parallel with the voltage limiting element 4 and is composed of a PNP type transistor, the emitter of which is connected to the cathode side of the Zener diode constituting the voltage limiting element 4, and its collector There is connected to the anode side of the Zener diode, so as to form a bypass circuit and converted from off to on by a reduction in its base potential. Reference numeral 7 denotes a bias resistor connected between the emitter and base of the bypass transistor .
[0015]
Reference numeral 8 is a detection transistor constituting detection means for detecting the value of the voltage drop generated in the current detection resistor 11, which is composed of an NPN type transistor, the emitter of which is connected to the negative side of the DC power supply 2, The base is connected to the negative side of the DC power supply 2 via the current detection resistor 11 , and its collector is connected to the bypass transistor base via the resistor 9. Reference numeral 10 denotes a bias resistor connected to the collector of the detection transistor 8, and when a current of a predetermined value or more flows through the current detection resistor 11 , the detection transistor 8 is turned from OFF to ON by a voltage value of a corresponding voltage drop. It is supposed to change. The bypass transistor 6 is turned on when the detection transistor 9 is turned on.
[0016]
Next, the operation of the cooling fan motor voltage setting circuit according to the embodiment of the present invention will be described.
[0017]
With the start of use of the device, the power switch 3 is closed and a DC voltage is supplied to the cooling fan motor 1. At the start of supplying the DC voltage, the cooling fan motor 1 starts to rotate when a current larger than that in the steady state flows. Therefore, a large current also flows through the current detection resistor 11, and the value of the voltage drop there increases. Due to this large voltage drop value, the base potential of the detection transistor 8 is greatly displaced in the plus direction, and the detection transistor 8 that is off in the steady state is turned on. The base potential of the bypass transistor 6 is shifted in the negative direction, and the bypass transistor 6 is turned on from the off state in the steady state to form a bypass circuit. The formation of the bypass circuit supplies the cooling fan motor 1 with a high DC voltage that is not limited by the voltage limiting element 4.
[0018]
Therefore, the cooling fan motor 1 generates a high torque and immediately rotates toward high speed rotation. When the rotation is sufficient, the cooling fan motor 1 has a reduced load, and the flowing current decreases rapidly. When the current decreases, the value of the voltage drop at the current detection resistor 11 decreases, and the detection transistor 8 switches from on to off. More conversion to this off, the bypass transistor 6 is not formed a bypass circuit is converted to off again. Therefore, the voltage supplied to the cooling fan motor 1 is a value at which the fan reduced by the voltage limiting element 4 does not generate wind noise.
[0019]
Here, a period in which a bypass circuit is formed and a high voltage is supplied to the cooling fan motor 1 at the time of start-up is achieved by setting in advance the timing for turning on and off the detection transistor 8. In this embodiment, the on / off switching timing of the detection transistor 8 can be finely adjusted by varying the resistance value of the current detection resistor 11. Therefore, the minimum period required for starting the cooling fan motor 1 can be arbitrarily set, and the influence of wind noise can be reliably eliminated. Further, in large-scale and multi-product production, even if the cooling fan motor 1 having a different voltage standard circuit and a different standard is adopted, the optimum state can be set, so that the cost can be reduced.
[0020]
According to an example of the embodiment of the present invention, a large current flows through the cooling fan motor 1 when the power switch 3 is closed at the start of use of the device. In this state, the voltage drop in the current detection resistor 11 can be directly detected by the detection transistor 8. Then, the bypass transistor 6 is turned on to form a bypass circuit, and a high voltage is supplied to the cooling fan motor 1 to achieve startup in a short period of time. When the start-up of the cooling fan motor 1 is achieved, the load is reduced and the current is rapidly reduced, so that the detection transistor 8 is turned off and the bypass transistor 8 is turned off. By switching off, a bypass circuit is not formed, and the cooling fan motor 1 is supplied with the voltage reduced by the voltage limiting element 4 so that no wind noise is generated and the cooling fan motor 1 operates with a certain degree of cooling effect. . In this way, the cooling fan motor can be quickly activated so that no wind noise is generated at the stage of substantial use of the device body. In particular, the effect is great in acoustic equipment that handles audio signals.
[0021]
Next, another example of the embodiment of the present invention will be described with reference to FIG. 2, but the same parts as those in the example of the embodiment in FIG.
[0022]
In another example, the cooling fan motor 1 in series, are connected in series as a solid-state resistance resistor for current detection to 5 having a specific resistance value. The emitter and base of a detection transistor 8 forming detection means are connected to both ends thereof.
[0023]
According to another example of the embodiment of the present invention , the detection transistor 8 is turned on / off as in the case where the variable resistance shown in the embodiment is used as the current detection resistor 11 . Although the timing of conversion cannot be finely adjusted, if a current detection resistor 5 having a desired resistance value is appropriately selected and used, a minimum period required for starting the cooling fan motor 1 can be set. is there.
[0024]
In the present invention, a Zener diode is used as the voltage limiting element 4 in one example and other examples of the embodiment, but the present invention is not limited to this, and a diode, a resistor, or the like may be used.
[0025]
【The invention's effect】
As described above, according to the first aspect of the present invention, since the change in the current flowing through the cooling fan motor can be directly detected by the detection transistor in the current detection resistor connected in series with the cooling fan motor, There is an effect that it is possible to provide an acoustic apparatus that substantially eliminates the influence of wind noise generated from the cooling fan by supplying a high voltage only for a minimum period necessary for the activation to complete the activation. In addition, since the configuration only needs to use a detection transistor, a bypass transistor, or the like, the effect can be achieved at low cost.
[0026]
According to the second aspect of the present invention, since the current change flowing through the cooling fan motor can be directly detected by the detecting means in the current detection resistor connected in series with the cooling fan motor, the cooling fan motor needs to be started. Thus, there is an effect that a high voltage is supplied only for a minimum period to complete the start-up, and a device substantially free from the effects of wind noise generated from the cooling fan can be provided.
[0027]
Furthermore, according to the third aspect of the present invention, since the current change flowing through the cooling fan motor can be directly detected by the detection transistor in the current detection resistor connected in series with the cooling fan motor, the cooling fan motor can be started. There is an effect that it is possible to provide a device in which the start-up is completed by supplying a high voltage for a necessary minimum period and the influence of wind noise generated from the cooling fan is substantially eliminated. In addition, since the configuration only needs to use a detection transistor, a bypass transistor, or the like, the effect can be achieved at low cost.
[0028]
Furthermore, according to the third aspect of the present invention, since the resistor whose value is variably set is used as the current detection resistor connected in series with the cooling fan motor, the detection state of the detection transistor or the detection means is finely adjusted. This has the effect of eliminating the adverse effects of reliable startup and wind noise.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of an embodiment of the present invention.
FIG. 2 is a block diagram showing another example of the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cooling fan motor 4 Voltage limiting element 5 Current detection resistor 6 Bypass transistor 8 Detection transistor

Claims

In an acoustic device having a cooling fan for cooling a heat source such as a hard disk drive, a power supply circuit, and a circuit board,
A DC power source that supplies a DC voltage to a cooling fan motor that drives the cooling fan, and a series connection between the DC power source and the cooling fan motor so that the cooling fan does not generate wind noise. A constant voltage element and a power switch that reduce the DC voltage of the DC power supply to a predetermined DC voltage for rotation and supply the cooling fan motor, and a current that flows through the cooling fan motor connected in series with the cooling fan motor Connected in parallel with the constant voltage element, a current detecting resistor for detecting the voltage drop generated by itself, a detection transistor for detecting a voltage drop value generated by the current detecting resistor, and a switching operation And a bypass transistor that is controlled by a switching operation of the detection transistor,
When the power switch is turned on, a larger current flows in the cooling fan motor than in a normal state corresponding to a load for starting the cooling fan, and a large current is generated in the current detection resistor due to the current flowing in the cooling fan motor. By detecting the value of the voltage drop, the detection transistor is switched from off to on , and by this switching operation, the bypass transistor is switched from off to steady on to short-circuit the constant voltage element, A direct current voltage is supplied from the direct current power source to the cooling fan motor through the bypass transistor in an on state, and a current flowing through the cooling fan motor as the load is reduced after the start of the cooling fan is completed. By suddenly decreasing, the value of the voltage drop generated in the current detection resistor is lowered and Detecting transistor is switching operation from ON to OFF, the said switching the bypass transistor by the operation is converted to off short of the constant voltage element is released, the predetermined through the constant voltage element to the cooling fan motor An acoustic device including a cooling fan motor voltage control circuit that is controlled so that the cooling fan rotates at the predetermined rotation speed by being supplied with a DC voltage.

In a device having a cooling fan for cooling a heat source such as a power supply circuit and a circuit board,
A direct current power source that supplies a direct current voltage to a cooling fan motor that drives the cooling fan, and a series connection between the direct current power source and the cooling fan motor so that the cooling fan does not generate wind noise. A constant voltage element and a power switch that reduce the DC voltage of the DC power supply to a predetermined DC voltage for rotation and supply the cooling fan motor, and a current that flows through the cooling fan motor connected in series with the cooling fan motor A current detecting resistor for detecting a voltage drop generated by the current detecting resistor, a detecting switching element for detecting a voltage drop generated by the current detecting resistor and performing a switching operation, and a parallel connection with the constant voltage element Bypass switching element controlled by switching operation of the detection switching element Have,
When the power switch is turned on, a larger current flows in the cooling fan motor than in a normal state corresponding to a load for starting the cooling fan, and a large current is generated in the current detection resistor due to the current flowing in the cooling fan motor. The detection switching element is switched from OFF to ON by detecting a voltage drop of the value, and by this switching operation, the bypass switching element is switched from OFF to ON in a normal state to short-circuit the constant voltage element. As a result, a direct current voltage is supplied from the direct current power source to the cooling fan motor through the bypass switching element in the on state, and the cooling fan motor is supplied to the cooling fan motor as the cooling fan is started and the load is reduced. The value of the voltage drop generated in the current detection resistor due to the sudden decrease in the flowing current. Lowering the detected switching element is a switching operation from ON to OFF, this said bypass switching element is converted to off by the switching operation short of the constant voltage element is released, the constant voltage to the cooling fan motor An apparatus comprising a cooling fan motor voltage control circuit that is controlled so that the cooling fan rotates at the predetermined rotation speed by supplying the predetermined DC voltage via an element.

In a device having a cooling fan for cooling a heat source such as a power supply circuit and a circuit board,
A DC power supply for supplying a DC voltage to a cooling fan motor that drives the cooling fan; and a DC power supply connected in series between the DC power supply and the cooling fan motor to reduce the DC voltage of the DC power supply to a Zener voltage. A zener diode and a power switch for supplying a predetermined DC voltage for rotating the cooling fan at a predetermined low rotation speed that does not generate wind noise to the cooling fan motor, and the cooling fan motor connected in series and flowing to the cooling fan motor A current detection resistor that detects current based on the value of the voltage drop generated in itself, a detection transistor that performs switching operation by detecting the value of the voltage drop generated in the current detection resistor, and the Zener diode connected in parallel The switching is controlled by the switching operation of the detection transistor. And a bypass transistor,
When the power switch is turned on, a larger current flows in the cooling fan motor than in a normal state corresponding to a load for starting the cooling fan, and a large current is generated in the current detection resistor due to the current flowing in the cooling fan motor. By detecting a voltage drop of the value, the detection transistor is switched from OFF to ON , and by this switching operation, the bypass transistor is switched from OFF to ON in a normal state to short-circuit the Zener diode, A DC voltage is supplied to the cooling fan motor from the DC power source through the bypass transistor, and the current flowing through the cooling fan motor suddenly increases as the cooling fan is completely started and the load is reduced. The value of the voltage drop generated in the current detection resistor is reduced. The detection transistor is switching operation from ON to OFF and, the said bypass transistor by the switching operation is a short circuit of the zener diode is converted to off is released, by the Zener voltage of the Zener diode to the cooling fan motor A device provided with a cooling fan motor voltage control circuit that is controlled so that the cooling fan rotates at the predetermined rotation speed by supplying the set predetermined DC voltage.

A bias resistor is connected between a connection point of the current detection resistor and the cooling fan motor and a base of the detection transistor, and the current detection resistor is a variable resistor whose resistance value can be variably set. A device comprising the cooling fan motor voltage control circuit according to claim 3.