JP3932777B2 - Active particle generating apparatus and active particle generating method - Google Patents

Description

【００２６】
表１は微生物が繁殖する物体１４として、寒天培地に人工的に植え付けたバクテリア（黄色ブドウ球菌）を保持したシャーレを用意し、負イオンとオゾンを含んだ混合ガス処理の効果を調べたものである。ここで、シャーレに供給するオゾンを含んだイオン化空気１０中の負イオン濃度は約１０⁶ 個／cm³ とした。この際、電離室５内の電極間に印加する電圧は約１５kVとした。
なお、微生物が繁殖する物体（シャーレ）１４に供給する空気１の温度は２０℃、湿度は８０〜９０％とし、負イオン濃度約１０⁶個／cm³で、オゾン濃度 ０．０３ppmのオゾンを含んだイオン化空気１０で３日間連続的に処理した。
比較項目として、負イオンおよびオゾンともに発生させずに２０℃の空気で処理した場合、負イオン濃度約１０⁶ 個／cm³ で、オゾン濃度０．００２ppm以下の２０℃のイオン化空気で処理した場合、およびオゾン濃度０．０５ppmで、負イオン濃度約１０² 個／cm³ 以下の２０℃のオゾン化空気で処理した場合を加えた。
【００２７】
実験結果は、表１に示したように、イオンおよびオゾンを発生させずに２０℃の空気で処理した場合、３日後のバクテリアのコロニー数は約９００個／シャーレであり、負イオン濃度約１０⁶個／cm³でオゾン濃度０.００２ppm以下の２０℃のイオン化空気で処理した場合、３日間の処理直後のバクテリアのコロニー数は約１００個／シャーレとなり、微生物の増殖抑制効果はみられたが、イオン処理を停止すると、バクテリアのコロニー数は約７００個／シャーレに達し、イオン処理では、十分な微生物増殖防止効果が得られないことがわかった。また、オゾン濃度０.０５ppmで負イオン濃度約１０²個／cm³以下の２０℃のオゾン化空気で処理した場合、３日後のバクテリアのコロニー数は約８００個／シャーレとなり、オゾン処理によりバクテリアの増殖は若干抑えられるが、その効果はあまり無いことが分った。
【００２８】
一方、温度２０℃、負イオン濃度約１０⁶個／cm³、オゾン濃度０.０３ppmのオゾンを含んだイオン化空気１０で処理した場合、３日後のバクテリアのコロニー数は０個／シャーレとなり、完全に増殖が抑制される効果が得られた。
また、オゾンを含んだイオン化空気１０で処理した寒天培地を、処理を止めて、そのまま室温（約２０℃）に放置した場合、バクテリアの再増殖はほとんど認められなかった。
【００２９】
以上のように上記実験結果によると、寒天培地に植え付けたバクテリアで、オゾンを含んだイオン化気体１０の方が、イオン化気体単独あるいはオゾン単独の場合に比べて、オゾンと負イオンの相乗効果により、微生物の増殖を防止する能力を大きくできるとともに、バクテリアを死滅させることができることが認められた。
【００３０】
なお、表１では、好気性の球菌である黄色ブドウ球菌を用いて、低濃度のオゾンを含んだイオン化気体の効果を示したが、他の細菌、例えば形態が違う緑膿菌、大腸菌やサルモネラ菌等の好気性の桿菌についても同様の効果が得られた。
また、胞子を形成する好気性の桿菌であるバチルス（Ｂａｃｉｌｌｕｓ）属細菌等や、真菌類であるカビ等についても同様の効果が得られ、増殖を抑制することができると考えられる。
【００３１】
本実験例では、オゾン濃度を約０.０３ppm、負イオン濃度を約１０⁶個／cm³とした場合のオゾンを含んだイオン化空気処理についての微生物増殖抑制効果を示したが、微生物が繁殖している物体１４に供給されるオゾンを含んだイオン化気体１０中の負イオン濃度およびオゾン濃度は、物体１４表面に存在している微生物の種類や処理方法等によって変更することが好ましい。
【００３２】
なお、上記実施の形態では、オゾンと負イオンを含んだイオン化気体１０を用いて処理した場合についての効果を示したが、昇圧変換器２２とパルス変換器２３よって正極性の直流パルス高電圧を作り出し、電離室５内の金属針電極７に正極性の直流パルス高電圧を印加して正イオンとオゾンを生成し、そのオゾンと正イオンを含んだイオン化気体１０を微生物が繁殖する物体１４に供給するようにしても同様の効果が得られるが、負イオンの方が正イオンに比べて微生物の繁殖を防止する効果が大きい。
【００３３】
また、昇圧変換器２２とパルス変換器２３よって交流パルス高電圧を作り出し、電離室５内の金属針電極７に交流パルス高電圧を印加して、負イオン、正イオンおよびオゾンを生成し、そのオゾンと正および負のイオンを含んだイオン化気体１０を微生物が繁殖する物体１４に供給するようにしても同様の効果が得られるが、イオン化気体１０中に負イオンと正イオンが同等量含まれていると、正イオンと負イオンが再結合して、イオンの消滅が早くなり、微生物の繁殖を防止する効果が小さくなる。したがって、気体１０中には単極性のイオンのみを発生させるようにすることが望ましい。
【００３４】
また、上記実施の形態では、処理期間中イオン濃度およびオゾン濃度を一定に維持して処理を行うものについて示したが、処理期間中、パルス周波数の値を変更するようにして、イオン濃度は高濃度に保ちながら、オゾン濃度だけを変化させて、微生物が繁殖する物体１４を処理するようにしてもよい。
【００３５】
さらに、また、上記実験例では電離室５において、金属針電極７と、これと対向して配置される金属平板接地電極と８を設けた場合の例を示したが、図３に示したように、電離室５には径が０.１〜０.２mm程度の複数の金属細線２４と、この金属細線２４と対向して配置される金属格子状接地電極２５を設け、この金属細線２４に負極性の直流パルス高電圧を印加させたときに起こる放電においても同様の効果があった。図３(ａ)は本発明の実施の形態１の微生物繁殖防止装置の変形例を示す構成図で、同図(ｂ)は金属細線２４部分を示す断面模式図である。
【００３６】
実施の形態２．
図４は本発明の実施の形態２による微生物繁殖防止装置を示す構成図であり、図において、２６は入力電源２１から供給される交流電圧を直流電圧に変換する整流器、２７は直流電圧を蓄えるコンデンサ、２８は直流電圧をパルス化するパルス発振器、２９は直流パルス電圧を昇圧するパルストランスである。ここで、パルス発生器はコンデンサ２７、パルス発振器２８、パルストランス２９で構成されている。なお、入力電源２１から供給される電圧が直流電圧である場合は、整流器２６は必要ない。
【００３７】
次に動作について説明する。
まず、ファン２が外部の気体１を供給口４から取り込み、通気路３を介して電離室５内に導く。
この電離室５内には、複数の金属針電極７と、この金属針電極７と対向して配置された金属平板接地電極８が、金属針電極７と金属平板接地電極８との間隔（ギャップ長）を数mmに保持して設けられている。
【００３８】
入力電源２１から整流器２６に交流電圧が供給され、そこで交流電圧が直流電圧に変換される。変換された直流電圧はコンデンサ２７に蓄えられるとともに、パルス発振器２８によってパルス化され、直流パルス電圧となってパルストランス２９に供給される。パルストランス２９で作られた直流パルス高電圧が金属針電極７に印加されると、金属針電極７の先端近傍に、高い電界がかかり、コロナ放電が起こる。
【００３９】
従って、酸素分子を含有している気体１が放電中の電離室５内に導かれると、気体１に含まれる酸素分子等と電子が付着することにより、酸素分子等が負イオン化するとともに、酸素分子が電子と衝突解離することにより、オゾンが生成されて、オゾンと負イオンの双方が含まれたオゾンを含むイオン化気体１０が発生することになる。
【００４０】
そして、パルス発振器２８により、金属針電極７に印加される負極性直流パルス高電圧のパルス周波数を制御しているので、放電時に流れる電流が低減されて、オゾンの生成量が抑制される。
なお、上述したように、オゾンは酸化力が強くオゾン濃度が高くなると有害であるため、イオン化気体１０中のオゾン濃度は作業基準値の０.１ppm以下になるように制御されている。
【００４１】
このようにして低濃度のオゾンを含んだイオン化気体１０を生成し、これを微生物が繁殖している物体１４に供給する。通常の場合は、空気を供給気体としているので、低濃度のオゾンを含んだイオン化空気１０が供給される。
而して、微生物が繁殖した物体１４表面に対してイオンおよびオゾンが継続して供給されることになるので、イオンとオゾンの相乗効果により、どちらか一方では微生物の繁殖を抑制できない濃度域でも、微生物の増殖を抑えられることになる。
なお、本実施の形態では、直流電圧をパルス発振器２８によりパルス化した後、パルストランス２９で昇圧して、直流パルス高電圧を作り出しているので、パルス発振器２８に耐高電圧のものを使用する必要がなくなり、装置コストが安くなる。
【００４２】
実施の形態３．
上記実施の形態２では、直流電圧をパルス発振器２８によりパルス化した後、パルストランス２９で昇圧して、直流パルス高電圧を作り出すものを示したが、図５の回路図で示したような電気回路を用いて、直流パルス高電圧を作り出すようにしても同様の効果が得られる。図において、３０ａ〜３０ｄは抵抗、３１ａ〜３１ｅはダイオード、３２ａ，３２ｂはコンデンサ、３３はサイリスタ、３４は昇圧トランスで、これらでパルス発生器を構成している。
【００４３】
次に動作について説明する。入力電源２１から供給された交流電圧をダイオード３１ａにより半波電圧に変換し、コンデンサ３２ｂに充電する。コンデンサ３２ｂに電荷が充電されると、コンデンサ３２ａと抵抗３０ｂから構成されたスイッチ部により、サイリスタ３３に信号が送られ、サイリスタ３３に電流が流れるようになると、コンデンサ３２ｂに蓄えられた電荷が昇圧トランス３４の一次側コイルに流れる。一次側コイルに電流が流れると、二次側コイルに起電力が発生し、交流のパルス高電圧が発生する。その発生した交流パルス高電圧をダイオード３１ｅによって半波整流し、直流パルス高電圧に変換する。
本実施例では、パルストランスを使用する必要がなく、通常のトランスを使用できるため、簡便で装置コストを低減できる。
【００４４】
参考例．
上記実施の形態１では、電離室５内の金属針電極７に負極性の直流パルス高電圧を印加するようにして、放電時に流れる電流を制御することによって、オゾン濃度を低く維持しつつ、負イオン濃度をできるだけ高めたイオン化気体１０を発生させる場合の例を示したが、図６の構成図に示すように、金属針電極７と対向して配置された金属平板接地電極８上に、セラミック、ガラス、石英等の誘電材料からなる平板状の誘電体９を蒸着または密着により取り付けるとともに、金属針電極７に直流高電圧を印加して、放電時に流れる電流を抑制するようにしても、オゾン濃度を低く維持しつつ、負イオン濃度をできるだけ高めたイオン化気体１０を発生させることができ、同様の微生物増殖抑制効果が得られる。誘電体９は放電電流制御手段として作用する。
【００４５】
ここで、この参考例における微生物繁殖防止装置で発生するオゾン量が、金属平板設置電極８に蒸着した誘電体９により低減できることを実証するために実施した他の実験例について説明する。
この実験例では、長さ１cmの金属針電極７を５mm間隔で５本配置し、この金属針電極７と、厚さ０.５mm の誘電体９を密着した幅１cm、長さ３cmの金属平板接地電極８のギャップ長を１０mm、金属針電極７に印加される負極性直流高電圧のゼロピーク電圧を８kV、両電極間を通過する空気の風速を 約５０cm／sとし、供給する空気の温度を２０℃、湿度を６０％とした。
【００４６】
このような条件下でイオンを発生させて、イオン発生量を測定した結果、イオン発生量は 約１×１０⁹個／ｓであり、誘電体９を取り除いた場合のイオン発生量は 約３×１０⁹個／ｓとなり、誘電体９の有無にかかわらず、負イオンの発生量はほぼ同等になることが確認された。
【００４７】
一方、放電により同時に発生するオゾンの発生量は、誘電体９が設置されていない場合、約１mg／hrであるが、誘電体９を取り付けることにより、オゾン発生量は約０.０１mg／hrに低下した。
以上のように、この参考例によれば、イオン化された気体１０のイオン濃度を十分高く維持しながら、オゾンを低濃度に維持できることがわかる。
また、この参考例では、パルス変換器２３を使用せずに、誘電体９の厚みを変更して、オゾンの発生量を低減化するとともに、制御しているので、装置構成が簡単で、装置を簡便に安く製作することができる効果がある。
【００４８】
実施の形態４．
図７は本発明の実施の形態４による微生物繁殖防止装置を示す構成図であり、図において、３５は微生物が繁殖する物体１４を収納する空間を有するとともに、電離室５において発生したオゾンを含むイオン化気体１０が供給されるイオン供給室である。
【００４９】
次に動作について説明する。
まず、ファン２がイオン供給室３５内部の気体１を供給口４から取り込み、通気路３を経て電離室５内に導く。
この電離室５内には、複数の金属針電極７と、この金属針電極７と対向して配置された金属平板接地電極８が、金属針電極７と金属平板接地電極８との間隔（ギャップ長）を数mmに保持して設けられている。ここで、昇圧変換器２２によって作られ、パルス変換器２３によってパルス化された数kVの負極性直流パルス高電圧を金属針電極７に印加すると、金属針電極７の先端近傍に、高い電界がかかり、コロナ放電が起こる。
【００５０】
従って、酸素分子を含有している気体１が放電中の電離室５内に導かれると、気体１に含まれる酸素分子等と電子が付着することにより、酸素分子等が負イオン化するとともに、酸素分子が電子と衝突解離することにより、オゾンが生成されて、オゾンと負イオンの双方が含まれたイオン化気体１０が生成する。
【００５１】
そして、この際、パルス変換器２３により、金属針電極７に印加される負極性直流パルス高電圧のパルス周波数を制御しているので、放電時に流れる電流が低減されて、オゾンの生成量が抑制される。
なお、オゾンは酸化力が強くオゾン濃度が高くなると有害であるため、気体１０中のオゾン濃度は作業基準値の０.１ppm以下になるように制御されている。
【００５２】
このようにして低濃度のオゾンを含んだイオン化気体１０が生成し、イオン供給室３５内の空間に放出される。通常の場合は、空気を供給気体としているので、低濃度のオゾンを含んだイオン化空気１０が供給される。
以上のように、微生物が繁殖した物体１４表面およびその物体１４を収納している空間に対してイオンおよびオゾンが継続して供給されることになるので、イオンとオゾンの相乗効果により、物体１４表面にすでに存在している微生物およびイオン供給室３５内の空間に浮遊し、物体１４表面に落下して新たに増殖を開始する微生物の増殖を抑えられることになる。
【００５３】
次に、低濃度のオゾンを含んだイオン化気体１０によって、イオン供給室３５内に収納された物体表面に存在する微生物の繁殖が抑えられることを実験例を用いて説明する。
【００５４】
【表２】

【００５５】
表２はこの実験例の実験結果を示したものであり、実験は微生物が繁殖する物体１４として鮪刺身を用い、これをイオン供給室３５、この場合は冷蔵庫内に温度０℃、湿度８５〜９５％の条件で３日間保存し、電離室５で発生したオゾンと負イオンを含んだ空気で連続的に処理したものである。
なお、電離室５内の金属針電極７に約−１０kVの電圧を印加して、イオン供給室３５内の負イオン濃度は約１０⁵個／cm³とし、オゾン濃度は約０.０５ppmとした。
【００５６】
比較項目として、負イオンおよびオゾンともに発生させずに０℃の空気で処理した場合、負イオン濃度約１０⁵個／cm³で、オゾン濃度０.００２ppm以下の０℃のイオン化空気で処理した場合、およびオゾン濃度約０.２ppmで、負イオン濃度約１０²個／cm³以下の０℃のオゾン化空気で処理した場合を加えた。なお、鮪刺身１４の表面の一般細菌のサンプリングはスタンプ法により、培地は標準寒天培地を用いた。
【００５７】
実験結果は、表２に示したように、イオンおよびオゾンを発生させずに空気で処理した場合、３日後のバクテリアのコロニー数は約１６００個／cm² であり、負イオン濃度約１０⁵ 個／cm³ でオゾン濃度０.００２ppm以下のイオン化空気で処理した場合、３日後のバクテリアのコロニー数は約１０００個／cm² となり、バクテリアの増殖は若干抑えられるが、その効果はあまり無いことが分った。
【００５８】
また、オゾン濃度約０.２ppmで負イオン濃度約１０² 個／cm³ 以下のオゾン化空気で処理した場合、３日後のバクテリアのコロニー数は約６００個／cm² となり、バクテリアの増殖はかなり抑えられる。ところが、オゾンで処理した場合、鮪刺身の外観はオゾンの強力な酸化作用により色が赤黒く変色し、品質が著しく低下するという問題が生じた。
【００５９】
一方、温度０℃、負イオン濃度約１０⁵個／cm³、オゾン濃度０.０５ppmのオゾンを含んだイオン化空気１０で処理した場合、３日後のバクテリアのコロニー数は約３００個／cm² シャーレとなり、増殖がかなり抑制されるという効果が得られた。また、処理３日後においても、外観の変化がみられず、また腐敗臭も感じられず、ほぼ初期の鮮度を完全に維持することができることが認められた。
【００６０】
以上のように上記実験結果によると、低濃度のオゾンと高濃度の負イオンを含んだイオン化空気により、鮪刺身を高濃度のオゾン処理のように変色・変質させることなく、その表面に存在する微生物の繁殖を防止でき、初期の鮮度を維持できることがわかる。
【００６１】
上記実施の形態では、処理期間中イオン濃度およびオゾン濃度を一定に維持して処理を行うものについて示したが、処理期間中、パルス周波数の値を変更するようにして、イオン濃度は高濃度に保ちながら、オゾン濃度だけを変化させて、イオンでは連続処理およびオゾンでは間欠処理を行うようにしても、低濃度のオゾンと高濃度の負イオンを含む空気１０で連続処理するよりも、微生物増殖防止効果はやや低下するが、ほぼ同様の効果が得られる。
【００６２】
実施の形態５．
図８は本発明の実施の形態５による微生物繁殖防止装置を示す構成図であり、図において、３６は気体流制御手段で、この場合は金属針電極７と金属平板接地電極８の間の空間に気体１を強制的に流すとともに、気体流路断面を狭め両電極７，８間に流れる気体１の流速を速めるガス流方向制御板である。
【００６３】
次に動作について説明する。
まず、ファン２が外部の気体１を供給口４から取り込み、通気路３を経てガス流方向制御板３６に導く。
このガス流方向制御板３６に導かれた気体１は、ガス流方向制御板３６により流れる方向を変更され、電離室５内に設けられた複数の金属針電極７と、この金属針電極７と対向して配置された金属平板接地電極８との間の放電空間に供給される。ここで、昇圧変換器２２によって作られ、パルス変換器２３によってパルス化された数kVの負極性直流パルス高電圧を金属針電極７に印加すると、金属針電極７の先端近傍に、高い電界がかかり、コロナ放電が起こる。
【００６４】
そして、酸素分子を含有している気体１が放電中の電離室５内に導かれると、気体１に含まれる酸素分子等と電子が付着することにより、酸素分子等が負イオン化するとともに、酸素分子が電子と衝突解離することにより、オゾンが生成されて、オゾンと負イオンの双方が含まれたイオン化気体１０が生成される。
【００６５】
また、この度、金属針電極７と金属平板接地電極８の両電極間に流れる気体１のガス流速と、オゾンおよび負イオンの発生量の関係を実験により調べた結果、ガス流速が早くなるほど、負イオンの発生量は増加するが、オゾンの発生量は変わらないことが確認された。
このことから、両電極７，８間に流す気体１の流速を高めることにより、オゾンの生成量を抑制しながら、気体１中に高濃度の負イオンを発生させることができるようになることが分かる。
【００６６】
本実施の形態５においては、放電時に流れる電流を抑制するように構成するとともに、ガス流方向制御板３６により金属針電極７と金属平板接地電極８間に流れる気体の流速を速くしているので、オゾンの発生を抑制してオゾン濃度を低濃度に維持しつつ、負イオンの発生量をより良好に増加させることができ、より高濃度の負イオンを含むイオン化気体が得られる。
このようにして生成した低濃度のオゾンおよび高濃度のイオンを含んだイオン化気体１０が微生物が繁殖している物体１４に供給されると、上記実施の形態と同様、イオンとオゾンの相乗効果により微生物の増殖を抑えられる。
【００６７】
なお、ガス流方向制御板３６の設置場所は、生成したイオンの衝突による消滅を防ぐという点から、電離室５の上流側に設けるのが望ましい。
【００６８】
実施の形態６．
上記実施の形態５では、金属針電極７と金属平板接地電極８間の放電空間に、ガス流方向制御板３６により気体１を流すものを示したが、図９の電離室５部分を示す模式斜視図に示したように、電離室５内において、０.１〜０.２mm程度の複数の金属細線２４と、この金属細線２４と対向して配置された金属格子状接地電極２５を設けるとともに、この金属細線２４の上流側にガス流方向制御板３６を設けて、金属細線電極２４近傍のみに気体１が流れるようにし、気体流路を絞って気体１の流速が速くなるようにしても同様の効果が得られる。
また、放電電極を金属細線としていることにより、金属細線近傍に気体１を流す際の圧力損失を小さくすることができ、大風量の気体をながすことができる効果がある。
【００６９】
実施の形態７．
図１０は本発明の実施の形態７による微生物繁殖防止装置を示す構成図であり、図において、３７は一方の通気路内に設置され、ファン２により取り込まれる気体１中のオゾンを分解するためのオゾン分解装置であり、本実施の形態では二酸化マンガン、活性アルミナ等のオゾン分解触媒が用いられている。また、３８は一方の通気路と他方の通気路の合流部分に設けられ、オゾン分解装置３７を通過する気体１の流量と通過しない気体１の流量の比率を制御し、電離室５に取り込まれる気体中のオゾン濃度を調節するガス流量制御装置である。このオゾン分解装置とガス流量制御装置でオゾン濃度調節手段を構成している。
【００７０】
次に動作について説明する。
まず、ファン２およびガス流量制御装置３８により、オゾン分解装置３７を通過する気体１と通過しない気体１が、ある混合比率で混合されて取り込まれ、通気路３を介して電離室５内に導かれる。
この電離室５内には、複数の金属針電極７と、この金属針電極７と対向して配置された金属平板接地電極８が、金属針電極７と金属平板接地電極８との間隔（ギャップ長）を数mmに保持して設けられている。ここで、昇圧変換器２２によって作られ、パルス変換器２３によってパルス化された数kVの負極性直流パルス高電圧を金属針電極７に印加されると、金属針電極７の先端近傍に、高い電界がかかり、コロナ放電が起こる。
【００７１】
この放電中の電離室５内に酸素分子を含有している気体１が導かれると、気体１に含まれる酸素分子等と電子が付着することにより、酸素分子等が負イオン化するとともに、酸素分子が電子と衝突解離することにより、オゾンが生成されて、オゾンと負イオンの双方が含まれたイオン化気体１０が取り出される。
【００７２】
この際、オゾン分解装置３７とガス流量制御装置３８により、電離室５に吸入される気体１中のオゾン濃度が一定に維持されるようにしているので、電離室５ではオゾンを一定量を発生させるようにするだけで、一定濃度のオゾンを含んだイオン化気体１０が微生物が繁殖している物体１４に供給できる。
これにより、微生物が繁殖する物体１４に供給するオゾンを含んだイオン化気体１０中のオゾン濃度を制御しやすくなるとともに、高濃度に達すると有害であるオゾンを低い濃度域に維持でき、安全で効率的に微生物の増殖を防止することができる。
【００７３】
実施の形態８．
上記実施の形態７では、オゾン分解装置３７とガス流量制御装置３８により、電離室５に吸入される気体１中のオゾン濃度が一定に維持されるものを示したが、図１１の構成図に示したように、電離室５の上流側に、オゾン分解用加熱電線３９を設けて、オゾン分解用加熱電線３９の温度が一定になるように制御して、気体１中のオゾンが常に一定量分解されるようにして、電離室５に吸入される気体１中のオゾン濃度が一定に維持されるようにしても同様の効果が得られる。
また、部品点数を低減でき、装置の構成が簡単で、制御が容易になる。
【００７４】
実施の形態９．
図１２は本発明の実施の形態９による微生物繁殖防止装置を示す構成図であり、図において、４０は金属針電極７に流れ込む電流値を測定する電流計、４１は電流計４０からの入力信号を受けて、昇圧変換器２２に出力信号を送る制御装置である。
【００７５】
次に動作について説明する。
まず、ファン２が外部の気体１を供給口４から取り込み、通気路３を介して電離室５内に導く。
この電離室５内には、複数の金属針電極７と、この金属針電極７と対向して配置された金属平板接地電極８が、金属針電極７と金属平板接地電極８との間隔（ギャップ長）を数mmに保持して設けられている。ここで、昇圧変換器２２によって作られ、パルス変換器２３によってパルス化された数kVの負極性直流パルス高電圧を金属針電極７に印加すると、金属針電極７の先端近傍に、高い電界がかかり、コロナ放電が起こり、低濃度のオゾンと負イオンが含まれたイオン化気体１０が生成される。
【００７６】
なお、この実施の形態では、この際に、電流計４０により金属針電極７に流れ込む電流値を計測している。そして、電流値が増加傾向にあることが認識されると、電流計４０から制御装置４１に信号が送られ、制御装置４１から昇圧変換器２２に信号が送られて、金属針電極７に印加される電圧が低減され、放電時に流れる放電電流が増加して、オゾンの生成量が増加するのを防止できるようにしている。
【００７７】
また、電流計４０で電流の増減を絶えず測定することは電極の汚れ具合をモニタリングすることになるので、金属針電極７のメンテナンス時期を容易に知ることができるようになる。
さらにまた、異常電流が流れた場合は、金属針電極７に高電圧を印加することを停止でき、火災などが発生するのを未然に防止することができる。
これにより、微生物が繁殖する物体１４に供給するオゾンを含んだイオン化気体１０中のオゾン濃度を制御しやすくなるとともに、高濃度に達すると有害であるオゾンを低い濃度域に維持でき、安全で効率的に微生物の増殖を防止することができる。
【００７８】
実施の形態１０．
上記実施の形態９では、電流計４０により、金属針電極７に流れ込む電流値を計測し、制御装置４１を介して電流計４０から昇圧変換器２２に信号を送り、金属針電極７に印加される電圧が低減させるようにして、気体１中のオゾン濃度が一定に維持されるものを示したが、図１３の構成図で示したように、金属平板接地電極８とアースとの間に、電流計４０を設けて、両電極７，８間に流れる放電電流を測定するようにしても同様の効果が得られる。
また、電流計４０を高電圧が印加されていない部分に設置しているので、電流計４０の仕様を高電圧仕様にする必要がなく、装置コストを低減できる効果がある。
【００７９】
【発明の効果】
以上のように、本発明の活性粒子発生方法においては、活性粒子発生電極に供給する電圧を間欠的にするパルス発生器を備え、上記パルス発生器のパルス周波数を制御して、イオン濃度をほぼ一定に保ちながらオゾン濃度を変化させ、０．１ｐｐｍ以下のオゾンと少なくとも１０ ⁴ 個／ｃｍ ³ のイオンを発生させるようにしたので、オゾン濃度を低濃度域に保ちながら、微生物の増殖防止能力の高い活性粒子発生方法を得ることができる。
【図面の簡単な説明】
【図１】 本発明の実施の形態１による微生物繁殖防止装置を示す構成図である。
【図２】 本発明の実施の形態１に係るパルス周波数と負イオンおよびオゾンの発生量との関係を示す特性図である。
【図３】 本発明の実施の形態１による微生物繁殖防止装置の変形例を示す構成図である。
【図４】 本発明の実施の形態２による微生物繁殖防止装置を示す構成図である。
【図５】 本発明の実施の形態３に係る微生物繁殖防止装置のパルス発生器の構成を示す回路図である。
【図６】 本発明の参考例による微生物繁殖防止装置を示す構成図である。
【図７】 本発明の実施の形態４による微生物繁殖防止装置を示す構成図である。
【図８】 本発明の実施の形態５による微生物繁殖防止装置を示す構成図である。
【図９】 本発明の実施の形態６による微生物繁殖防止装置の電離室部分を示す模式斜視図である。
【図１０】 本発明の実施の形態７による微生物繁殖防止装置を示す構成図である。
【図１１】 本発明の実施の形態８による微生物繁殖防止装置を示す構成図である。
【図１２】 本発明の実施の形態９による微生物繁殖防止装置を示す構成図である。
【図１３】 本発明の実施の形態１０による微生物繁殖防止装置を示す構成図である。
【図１４】 従来の微生物繁殖防止装置を示す構成図である。
【符号の説明】
１ 気体、２ ファン、３ 通気路、４ 供給口、５ 電離室、７ 金属針電極、８ 金属平板接地電極、９ 誘電体、１０ オゾンを含むイオン化気体、 １４ 物体、２１ 入力電源、２２ 昇圧変換器、２３ パルス変換器、２４ 金属細線電極、２５ 金属格子状接地電極、２６ 整流器、２７ コンデンサ、２８ パルス発振器、２９ パルストランス、３０ａ〜３０ｄ 抵抗、３１ａ〜３１ｄ ダイオード、３２ａ，３２ｂ コンデンサ、３３ サイリスタ、３４ トランス、３５ イオン供給室、３６ ガス流方向制御板、３７ オゾン分解装置、３８ ガス流量制御装置、３９ オゾン分解用加熱電線、４０ 電流計、 ４１ 制御装置。[0001]
BACKGROUND OF THE INVENTION
The present invention uses active particles such as ions and ozone to provide food, cooking utensils, and other food-related foods necessary for consumption, as well as object surfaces that require prevention of microbial growth for public health, and those The present invention relates to a method for preventing the growth of microorganisms and a device therefor, which prevent the growth of microorganisms existing in a space for storing the object.
[0002]
[Prior art]
FIG. 14 is a block diagram showing a conventional microbial growth prevention apparatus disclosed in, for example, Japanese Patent Laid-Open No. 7-115946, in which 1 is an external gas, 2 is a fan (blower) for taking in gas 1, and 3 is a fan 2 is an air passage through which the gas 1 taken in by 2 is vented, 4 is a supply port for taking in the gas 1, 5 is installed in the air passage 3, and the gas 1 is removed by ionizing electrons to the taken-in gas 1. An ionization chamber for ionization, 6 is a bushing made of an insulating material, 7 is a metal needle electrode made of a metal material such as tungsten, stainless steel, or nickel, 8 is a metal flat plate ground electrode arranged facing the metal needle electrode 7, 9 Is a plate-like dielectric made of a dielectric material such as ceramic, glass, quartz, or the like, which is attached to the metal flat plate ground electrode 8 by vapor deposition or adhesion, and 10 is an ozono ionized in the ionization chamber 5 11 is installed in the air passage 3, decomposes ozone contained in the ionized gas 10 containing ozone in the ionization chamber 5, and removes ozone from the ionized gas 10 containing ozone. The ozone decomposition chamber is filled with an ozone decomposition catalyst such as manganese dioxide or activated alumina. 12 is an insulator that electrically insulates the ozone decomposition chamber 11 from the air passage 3, 13 is an ionized gas that does not contain ozone, 14 is an object through which microorganisms propagate, and 15 is a space that houses an object 14 through which microorganisms propagate. The ion treatment chamber is supplied with ionized gas 13 that does not contain ozone and has ozone removed in ozone decomposition chamber 11, 16 is a high-pressure generator, and 17 ionizes ionized gas 13 that does not contain ozone. A gas inlet 18 for supplying to the processing chamber 15 is a gas outlet for releasing the ionized gas 13 containing no used ozone outside the ion processing chamber 15.
[0003]
Next, the operation will be described.
First, the fan 2 takes in the external gas 1 from the supply port 4 and guides it into the ionization chamber 5 through the air passage 3.
In the ionization chamber 5, there are a plurality of metal needle electrodes 7 and a metal flat plate ground electrode 8 attached in close contact with a dielectric 9 disposed opposite to the metal needle electrodes 7. The gap (gap length) is set to several millimeters. When an AC high voltage of several kV is applied between the electrodes 7 and 8, a high electric field is applied near the tip of the metal needle electrode 7 and corona discharge. A discharge called occurs.
When the gas 1 is introduced into the ionization chamber 5 during discharge, the oxygen molecules and the like contained in the gas 1 collide with each other and the oxygen molecules and the like are ionized, so that the gas 1 contains ions.
[0004]
However, since the external gas 1 contains oxygen molecules, ozone is generated simultaneously with the generation of ions by corona discharge. Incidentally, since this ozone has strong oxidizing power, it is harmful when the ozone concentration becomes high.
Therefore, an ozone decomposition catalyst is disposed in the ozone decomposition chamber 11 in an electrically insulating manner from the air passage 3 on the downstream side in the air passage 3 through which the ionized gas 10 containing ozone flows, and ozone is contained by the ozone decomposition catalyst. Ozone is removed from the ionized gas 10 to produce an ionized gas 13 that does not contain ozone.
[0005]
In this way, the ionized gas 13 that does not contain ozone is supplied to the ion processing chamber 15 having a space for housing the object 14 on which the microorganisms propagate, and the propagation of microorganisms attached to the object 14 is suppressed.
[0006]
[Problems to be solved by the invention]
A conventional microbial growth prevention apparatus is configured as described above, and ions generated by this apparatus have an effect of suppressing the growth of microorganisms. However, there is a limit to the amount of ions that can be generated, and the higher the ion concentration in the gas, the greater the amount of ion self-decomposition. There was a point. In addition, with ions alone, there is a problem that when the ion treatment is stopped, a sufficient microorganism growth inhibitory effect cannot be obtained, for example, microorganisms start growing again.
On the other hand, in order to suppress the growth of microorganisms using ozone, it is necessary to treat with an ozone concentration of 0.1 ppm or more, but in the concentration range of 0.1 ppm or more, due to the high oxidizing power of ozone, For example, some foods have problems such as discoloration and alteration, and corrosion of equipment.
[0007]
As a result of intensive studies in order to solve the above problems, the present invention includes ozone controlled to a low concentration in a gas containing ions that suppress the growth of microorganisms, and synergies between ozone and ions. It has been found that the ability to prevent the growth of microorganisms can be enhanced by the effect.
[0008]
  Object of the present inventionHas a high ability to prevent the growth of microorganisms, which can generate ions at a high concentration, and can also control ozone to a low concentration by suppressing the amount of ozone generated.Active particle generation methodIs to get.
[0011]
[Means for Solving the Problems]
  The active particle generation method of the present invention is a gas containing oxygen supplied by a fan to the active particle generation chamber by a discharge caused by applying a direct current pulse voltage between the active particle generation electrodes arranged in the active particle generation chamber. Is an active particle generation method for ionizing and ozonizing, controlling the pulse frequency of the DC pulse voltage while keeping the flow rate of the gas constant,The ozone concentration is controlled while keeping the ion concentration substantially constant, and ozone of 0.1 ppm or less and at least 10 ^Four Piece / cm ^Three This generates a gas containing the ions.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a microbial growth preventing apparatus according to Embodiment 1 of the present invention. In the figure, 1 is an external gas, 2 is a fan that takes in gas 1, 3 is an air passage through which gas 1 taken in by fan 2 is vented, 4 is a supply port for taking in gas 1, and 5 is installed in air passage 3 An active particle generation chamber that ionizes and ozonizes the gas 1 taken in by discharge generated by applying a high voltage between the active particle generation electrodes described below. In this case, an ionization chamber, 6 is made of an insulating material. Bushings 7 and 8 are active particle generating electrodes. In this case, a metal needle electrode 7 made of a metal material such as tungsten, stainless steel, nickel, etc., and a metal flat plate ground electrode 10 facing the metal needle electrode 7, 10 Is an ionized gas containing ozone ionized in the ionization chamber 5 (referred to as ionized gas), 14 is an object on which microorganisms propagate, 21 is a discharge in the vicinity of the metal needle electrode 7 An input power supply for supplying electric power as a high voltage source, 22 is a boost converter for converting and boosting the primary voltage supplied from the input power supply 21, and 23 is a pulsed high voltage boosted by the boost converter 22. This is a pulse converter. In the present embodiment, a case will be described in which the input power supply 21 is set to AC 100 V, and the input AC 100 V is output as a negative DC high voltage by the boost converter 22.
[0015]
Next, the operation will be described.
First, the fan 2 takes in the external gas 1 from the supply port 4 and guides it into the ionization chamber 5 through the ventilation path 3.
In the ionization chamber 5, a plurality of metal needle electrodes 7 and a metal flat plate ground electrode 8 disposed so as to face the metal needle electrode 7 are spaced between the metal needle electrode 7 and the metal flat plate ground electrode 8 ( (Gap length) is maintained at several mm. Here, when a negative DC pulse high voltage of several kV produced by the step-up converter 22 and pulsed by the pulse converter 23 is applied to the metal needle electrode 7, a high electric field is generated near the tip of the metal needle electrode 7. Corona discharge occurs.
[0016]
When the gas 1 containing oxygen molecules is introduced into the ionization chamber 5 during discharge, the oxygen molecules and the like contained in the gas 1 are attached to the electrons, thereby negatively ionizing the oxygen molecules and the like. Oxygen molecules collide and dissociate with electrons to generate ozone, and ionized gas 10 containing ozone containing both ozone and negative ions is generated.
[0017]
In addition, in the present embodiment, since the pulse frequency of the negative DC pulse high voltage applied to the metal needle electrode 7 is controlled by the pulse converter 23, the current flowing during discharge is reduced, and the amount of ozone generated Is suppressed.
In addition, since ozone has a strong oxidizing power and a high ozone concentration, it is harmful to the human body and may corrode the material of the constituent object. Therefore, the ozone concentration in the ionized gas 10 is considered to be safe. It is necessary to control so that the reference value is 0.1 ppm or less. In addition, when applying such a gas containing ozone to food preservation, it has been found through experiments that if the ozone concentration exceeds 0.05 ppm, the food itself will be altered and discolored. When using gas, it became clear that the ozone concentration should be 0.05 ppm or less.
[0018]
Therefore, in the present embodiment, the amount of ozone generated is suppressed as described above, and the ionized gas 10 containing low-concentration (0.05 ppm or less) ozone is generated. To supply. In a normal case, since air is used as the supply gas 1, ionized air 10 containing low-concentration ozone is supplied.
Further, the ion concentration in the ionized air 10 at this time depends on the state of the object 14 on which the microorganisms are propagated.^Three It is necessary to increase the concentration to several hundred times, and when this concentration range is reached, microorganisms (bacteria) that prevent growth appear. However, the ion concentration is preferably 1000 times or more, that is, 10 times.^FourPiece / cm^ThreeThe above is effective in preventing the growth of various microorganisms. Therefore, 10^FourPiece / cm^ThreeThe ionized gas containing the above high concentration ions is supplied.
As described above, since ions and ozone are continuously supplied to the surface of the object 14 on which microorganisms have propagated (attached), the proliferation of microorganisms is suppressed on either side due to the synergistic effect of ions and ozone. Even in a concentration range where it is impossible, the growth of microorganisms can be suppressed.
[0019]
Here, a description will be given of an experimental example carried out to demonstrate that only a large amount of negative ions can be generated while maintaining the ozone concentration in the ionized gas 10 at a low concentration by controlling the current flowing during discharge.
FIG. 2 is a characteristic diagram showing the relationship between the pulse frequency of the applied voltage and the amount of negative ions and ozone generated. The solid characteristic curve indicates the relationship between the pulse frequency and the negative ion generation amount, and the broken characteristic curve indicates the relationship between the pulse frequency and the ozone generation amount. In this experimental example, five metal needle electrodes 7 each having a length of 1 cm are arranged at intervals of 5 mm, and the gap length between the metal needle electrode 7 and a metal flat plate ground electrode 8 having a width of 1 cm and a length of 3 cm is 10 mm. The negative peak DC pulse high voltage applied to 7 is 8 kV, the air velocity passing between both electrodes is about 1 m / s, the temperature of the supplied air is 20 ° C., and the humidity is 60%. It is.
[0020]
As can be seen from FIG. 2, it was confirmed that the ozone generation amount increased in a linear function as the pulse frequency increased, but the negative ion generation amount became substantially constant.
For example, when the pulse frequency is 500 Hz, the negative ion concentration is 3 × 10 3 while maintaining the ozone concentration in the air with a gas flow rate of 50 L / min at 0.03 ppm.⁶ Piece / cm^Three Can be.
Thus, it can be seen that by controlling the pulse frequency, the negative ion concentration can be increased while keeping the ozone concentration in a low concentration region.
[0021]
In the above experimental example, the number of needles of the metal needle electrode 7 is the same as the area of the metal plate ground electrode 8 of 3 cm² However, if the number is further increased, the amount of negative ions generated can be increased. However, since the amount of ozone generated increases at the same time, it is necessary to lower the pulse frequency.
[0022]
In the above experimental example, the zero peak voltage of the DC pulse high voltage is 8 kV and the gap length is 10 mm. However, if it is within a certain range (corona discharge region), the applied voltage can be further increased or the gap length can be increased. By further shortening, the amount of negative ions generated can be increased. However, since the amount of ozone generated increases at the same time, it is necessary to lower the pulse frequency. Furthermore, if the applied voltage is further increased beyond the above region or the gap length is further shortened, a short circuit occurs, which is very dangerous.
[0023]
In this experimental example, air with a wind speed of about 1 m / s was passed between the electrodes 7 and 8, but when the air wind speed was changed in the range of 0.1 to 3.0 m / s, negative ions were generated. The amount increases as the wind speed increases. However, since the flow rate of the air flowing through the air passage 3 increases, the ozone concentration in the air decreases, so it is necessary to increase the pulse frequency.
[0024]
Next, it will be described using experimental examples that the propagation of microorganisms can be suppressed by the ionized gas 10 containing ozone at a low concentration.
[0025]
[Table 1]

[0026]
Table 1 shows a petri dish holding bacteria (Staphylococcus aureus) artificially planted on an agar medium as an object 14 on which microorganisms propagate, and the effect of mixed gas treatment containing negative ions and ozone was examined. is there. Here, the concentration of negative ions in the ionized air 10 containing ozone supplied to the petri dish is about 10%.⁶ Piece / cm^Three It was. At this time, the voltage applied between the electrodes in the ionization chamber 5 was about 15 kV.
The temperature of the air 1 supplied to the object (petri dish) 14 on which the microorganisms propagate is 20 ° C., the humidity is 80 to 90%, and the negative ion concentration is about 10%.⁶Piece / cm^ThreeThen, it was continuously treated with ionized air 10 containing ozone having an ozone concentration of 0.03 ppm for 3 days.
As a comparison item, when processing with air at 20 ° C. without generating both negative ions and ozone, the concentration of negative ions is about 10⁶ Piece / cm^Three In the case of treatment with ionized air at 20 ° C. with an ozone concentration of 0.002 ppm or less, and at an ozone concentration of 0.05 ppm, a negative ion concentration of about 10² Piece / cm^Three The case where it processed with the following ozonized air of 20 degreeC was added.
[0027]
As shown in Table 1, the experimental results show that, when treated with air at 20 ° C. without generating ions and ozone, the number of bacterial colonies after 3 days is about 900 per petri dish, and the negative ion concentration is about 10⁶Piece / cm^ThreeWhen treated with ionized air at an ozone concentration of 0.002 ppm or less at 20 ° C., the number of bacterial colonies immediately after the treatment for 3 days was about 100 / dish, and an effect of suppressing the growth of microorganisms was observed. When stopped, the number of bacterial colonies reached about 700 / petri dish, and it was found that sufficient microbial growth prevention effect could not be obtained by ion treatment. The ozone concentration is 0.05 ppm and the negative ion concentration is about 10²Piece / cm^ThreeWhen treated with the following ozonized air at 20 ° C., the number of bacterial colonies after 3 days was about 800 per petri dish, and the growth of bacteria was slightly suppressed by ozone treatment, but it was found that the effect was not so much. .
[0028]
On the other hand, a temperature of 20 ° C. and a negative ion concentration of about 10⁶Piece / cm^ThreeIn the case of treatment with ionized air 10 containing ozone having an ozone concentration of 0.03 ppm, the number of bacterial colonies after 3 days was 0 per petri dish, and the effect of completely suppressing growth was obtained.
Moreover, when the agar medium treated with ionized air 10 containing ozone was stopped and allowed to stand at room temperature (about 20 ° C.), almost no bacterial regrowth was observed.
[0029]
As described above, according to the above experimental results, in the bacteria planted in the agar medium, the ionized gas 10 containing ozone has a synergistic effect of ozone and negative ions compared to the case of ionized gas alone or ozone alone. It was found that the ability to prevent the growth of microorganisms can be increased and bacteria can be killed.
[0030]
Table 1 shows the effect of ionized gas containing low concentration of ozone using Staphylococcus aureus, aerobic cocci, but other bacteria such as Pseudomonas aeruginosa, Escherichia coli and Salmonella Similar effects were obtained with aerobic bacilli such as.
In addition, it is considered that the same effect can be obtained for Bacillus genus bacteria, which are aerobic bacilli that form spores, and fungi such as fungi, and the growth can be suppressed.
[0031]
In this experimental example, the ozone concentration is about 0.03 ppm and the negative ion concentration is about 10 ppm.⁶Piece / cm^ThreeIn this case, the effect of suppressing the growth of microorganisms in the treatment of ionized air containing ozone is shown. However, the negative ion concentration and the ozone concentration in the ionized gas 10 containing ozone supplied to the object 14 where the microorganisms are propagated are It is preferable to change according to the type of microorganisms present on the surface of the object 14, the treatment method, and the like.
[0032]
In the above-described embodiment, the effect in the case of processing using the ionized gas 10 containing ozone and negative ions has been shown. However, a positive DC pulse high voltage is generated by the boost converter 22 and the pulse converter 23. A positive DC pulse high voltage is applied to the metal needle electrode 7 in the ionization chamber 5 to generate positive ions and ozone, and the ionized gas 10 containing the ozone and positive ions is propagated to the object 14 where the microorganisms propagate. Even if it supplies, the same effect is acquired, but the effect of preventing the proliferation of microorganisms is larger in the negative ion than in the positive ion.
[0033]
Further, an AC pulse high voltage is created by the boost converter 22 and the pulse converter 23, and the AC pulse high voltage is applied to the metal needle electrode 7 in the ionization chamber 5 to generate negative ions, positive ions, and ozone. The same effect can be obtained by supplying the ionized gas 10 containing ozone and positive and negative ions to the object 14 on which the microorganism propagates. However, the ionized gas 10 contains equal amounts of negative ions and positive ions. In this case, positive ions and negative ions are recombined, and the disappearance of the ions is accelerated, and the effect of preventing the growth of microorganisms is reduced. Therefore, it is desirable to generate only unipolar ions in the gas 10.
[0034]
In the above-described embodiment, the ion concentration and the ozone concentration are kept constant during the treatment period. However, during the treatment period, the value of the pulse frequency is changed to increase the ion concentration. While maintaining the concentration, only the ozone concentration may be changed to treat the object 14 on which the microorganisms propagate.
[0035]
Furthermore, in the above experimental example, an example in which the metal needle electrode 7 and the metal flat plate ground electrode 8 disposed opposite to the metal needle electrode 7 are provided in the ionization chamber 5, is as shown in FIG. In addition, the ionization chamber 5 is provided with a plurality of fine metal wires 24 having a diameter of about 0.1 to 0.2 mm and a metal grid-like ground electrode 25 arranged to face the fine metal wires 24. The same effect was obtained in the discharge that occurs when a negative DC pulse high voltage is applied. FIG. 3 (a) is a block diagram showing a modification of the microbial growth preventing apparatus according to Embodiment 1 of the present invention, and FIG. 3 (b) is a schematic cross-sectional view showing a portion of a fine metal wire 24. FIG.
[0036]
Embodiment 2. FIG.
4 is a block diagram showing a microbial growth prevention apparatus according to Embodiment 2 of the present invention. In the figure, 26 is a rectifier that converts an AC voltage supplied from an input power supply 21 into a DC voltage, and 27 is a DC voltage store. A capacitor, 28 is a pulse oscillator that pulses DC voltage, and 29 is a pulse transformer that boosts DC pulse voltage. Here, the pulse generator includes a capacitor 27, a pulse oscillator 28, and a pulse transformer 29. Note that when the voltage supplied from the input power supply 21 is a DC voltage, the rectifier 26 is not necessary.
[0037]
Next, the operation will be described.
First, the fan 2 takes in the external gas 1 from the supply port 4 and guides it into the ionization chamber 5 through the ventilation path 3.
In the ionization chamber 5, a plurality of metal needle electrodes 7 and a metal flat plate ground electrode 8 disposed to face the metal needle electrode 7 are spaced from each other (gap between the metal needle electrode 7 and the metal flat plate ground electrode 8). (Long) is provided at several mm.
[0038]
An AC voltage is supplied from the input power source 21 to the rectifier 26, where the AC voltage is converted into a DC voltage. The converted DC voltage is stored in the capacitor 27 and is pulsed by the pulse oscillator 28 to be supplied to the pulse transformer 29 as a DC pulse voltage. When a DC pulse high voltage generated by the pulse transformer 29 is applied to the metal needle electrode 7, a high electric field is applied near the tip of the metal needle electrode 7 and corona discharge occurs.
[0039]
Therefore, when the gas 1 containing oxygen molecules is introduced into the ionization chamber 5 during discharge, oxygen molecules and the like contained in the gas 1 are attached to the electrons, thereby negatively ionizing the oxygen molecules and the like. When molecules collide and dissociate with electrons, ozone is generated, and ionized gas 10 containing ozone containing both ozone and negative ions is generated.
[0040]
Since the pulse frequency of the negative DC pulse high voltage applied to the metal needle electrode 7 is controlled by the pulse oscillator 28, the current flowing at the time of discharge is reduced, and the amount of ozone generated is suppressed.
Note that, as described above, ozone has a strong oxidizing power and is harmful when the ozone concentration becomes high. Therefore, the ozone concentration in the ionized gas 10 is controlled to be 0.1 ppm or less of the operation standard value.
[0041]
In this way, an ionized gas 10 containing a low concentration of ozone is generated and supplied to the object 14 on which the microorganisms are propagated. In normal cases, since air is used as the supply gas, ionized air 10 containing low-concentration ozone is supplied.
Thus, since ions and ozone are continuously supplied to the surface of the object 14 on which the microorganisms have propagated, the synergistic effect of the ions and ozone can prevent the growth of microorganisms on either side. The growth of microorganisms can be suppressed.
In the present embodiment, the DC voltage is pulsed by the pulse oscillator 28 and then boosted by the pulse transformer 29 to create a DC pulse high voltage. There is no need, and the device cost is reduced.
[0042]
Embodiment 3 FIG.
In the second embodiment, the DC voltage is pulsed by the pulse oscillator 28 and then boosted by the pulse transformer 29 to generate the DC pulse high voltage. However, the electric voltage as shown in the circuit diagram of FIG. Even if a DC pulse high voltage is produced using a circuit, the same effect can be obtained. In the figure, 30a to 30d are resistors, 31a to 31e are diodes, 32a and 32b are capacitors, 33 is a thyristor, 34 is a step-up transformer, and these constitute a pulse generator.
[0043]
Next, the operation will be described. The AC voltage supplied from the input power supply 21 is converted into a half-wave voltage by the diode 31a, and the capacitor 32b is charged. When the capacitor 32b is charged, a signal is sent to the thyristor 33 by the switch unit composed of the capacitor 32a and the resistor 30b. When a current flows through the thyristor 33, the charge stored in the capacitor 32b is boosted. It flows to the primary side coil of the transformer 34. When a current flows through the primary coil, an electromotive force is generated in the secondary coil, and an alternating pulse high voltage is generated. The generated AC pulse high voltage is half-wave rectified by the diode 31e and converted to a DC pulse high voltage.
In this embodiment, it is not necessary to use a pulse transformer, and a normal transformer can be used. Therefore, the apparatus cost can be reduced easily.
[0044]
Reference example.
  In the first embodiment, a negative DC pulse high voltage is applied to the metal needle electrode 7 in the ionization chamber 5 to control the current flowing at the time of discharge, thereby maintaining a low ozone concentration while maintaining a low ozone concentration. Although an example in the case of generating the ionized gas 10 with the ion concentration increased as much as possible has been shown, as shown in the configuration diagram of FIG. 6, the ceramic is formed on the metal flat plate ground electrode 8 arranged to face the metal needle electrode 7. A plate-like dielectric 9 made of a dielectric material such as glass or quartz is attached by vapor deposition or adhesion, and a DC high voltage is applied to the metal needle electrode 7 to suppress the current flowing during discharge. While maintaining the concentration low, the ionized gas 10 having a negative ion concentration increased as much as possible can be generated, and the same microbial growth inhibitory effect can be obtained. The dielectric 9 acts as a discharge current control means.
[0045]
  Where thisReference exampleAnother experimental example carried out in order to demonstrate that the amount of ozone generated in the microbial growth prevention apparatus in FIG. 1 can be reduced by the dielectric 9 deposited on the metal plate installation electrode 8 will be described.
  In this experimental example, five metal needle electrodes 7 having a length of 1 cm are arranged at intervals of 5 mm, and a metal plate having a width of 1 cm and a length of 3 cm in which the metal needle electrode 7 and a dielectric 9 having a thickness of 0.5 mm are in close contact. The gap length of the ground electrode 8 is 10 mm, the zero peak voltage of the negative DC high voltage applied to the metal needle electrode 7 is 8 kV, the wind speed of the air passing between both electrodes is about 50 cm / s, and the temperature of the supplied air is The temperature was 20 ° C. and the humidity was 60%.
[0046]
As a result of generating ions under such conditions and measuring the amount of generated ions, the amount of generated ions was about 1 × 10⁹The number of ions generated when the dielectric 9 is removed is about 3 × 10.⁹It was confirmed that the amount of negative ions generated was almost the same regardless of the presence or absence of the dielectric 9.
[0047]
  On the other hand, the amount of ozone generated simultaneously by discharge is about 1 mg / hr when the dielectric 9 is not installed, but the ozone generation amount is about 0.01 mg / hr by attaching the dielectric 9. Declined.
  As above, thisReference exampleAccording to the above, it is understood that ozone can be maintained at a low concentration while maintaining the ion concentration of the ionized gas 10 sufficiently high.
  Also thisReference exampleThen, without using the pulse converter 23, the thickness of the dielectric 9 is changed to reduce the amount of ozone generated and controlled, so the device configuration is simple and the device can be manufactured easily and inexpensively. There is an effect that can be done.
[0048]
Embodiment4.
  FIG. 7 shows an embodiment of the present invention.4In the figure, reference numeral 35 denotes an ion supply chamber to which an ionized gas 10 containing ozone generated in the ionization chamber 5 is supplied while having a space for housing an object 14 on which microorganisms propagate. It is.
[0049]
Next, the operation will be described.
First, the fan 2 takes in the gas 1 inside the ion supply chamber 35 from the supply port 4 and guides it into the ionization chamber 5 through the air passage 3.
In the ionization chamber 5, a plurality of metal needle electrodes 7 and a metal flat plate ground electrode 8 disposed to face the metal needle electrode 7 are spaced from each other (gap between the metal needle electrode 7 and the metal flat plate ground electrode 8). (Long) is provided at several mm. Here, when a negative DC pulse high voltage of several kV produced by the step-up converter 22 and pulsed by the pulse converter 23 is applied to the metal needle electrode 7, a high electric field is generated near the tip of the metal needle electrode 7. Corona discharge occurs.
[0050]
Therefore, when the gas 1 containing oxygen molecules is introduced into the ionization chamber 5 during discharge, oxygen molecules and the like contained in the gas 1 are attached to the electrons, thereby negatively ionizing the oxygen molecules and the like. When molecules dissociate with electrons, ozone is generated, and ionized gas 10 containing both ozone and negative ions is generated.
[0051]
At this time, since the pulse frequency of the negative DC pulse high voltage applied to the metal needle electrode 7 is controlled by the pulse converter 23, the current flowing at the time of discharge is reduced and the generation amount of ozone is suppressed. Is done.
Since ozone has a strong oxidizing power and is harmful when the ozone concentration becomes high, the ozone concentration in the gas 10 is controlled to be 0.1 ppm or less of the work standard value.
[0052]
In this way, the ionized gas 10 containing low-concentration ozone is generated and released into the space inside the ion supply chamber 35. In normal cases, since air is used as the supply gas, ionized air 10 containing low-concentration ozone is supplied.
As described above, ions and ozone are continuously supplied to the surface of the object 14 on which the microorganisms have propagated and the space in which the object 14 is stored. The growth of microorganisms already existing on the surface and the microorganisms floating in the space in the ion supply chamber 35 and falling on the surface of the object 14 and newly starting to grow can be suppressed.
[0053]
Next, it will be described using experimental examples that the ionized gas 10 containing low-concentration ozone can suppress the growth of microorganisms existing on the surface of the object stored in the ion supply chamber 35.
[0054]
[Table 2]

[0055]
Table 2 shows the experimental results of this experimental example. In the experiment, sashimi was used as the object 14 on which the microorganisms propagated, and this was placed in the ion supply chamber 35, in this case, in the refrigerator at a temperature of 0 ° C and a humidity of 85-85. It is stored for 3 days under the condition of 95% and continuously treated with air generated in the ionization chamber 5 and containing ozone and negative ions.
A voltage of about −10 kV is applied to the metal needle electrode 7 in the ionization chamber 5 so that the negative ion concentration in the ion supply chamber 35 is about 10^FivePiece / cm^ThreeThe ozone concentration was about 0.05 ppm.
[0056]
As a comparison item, when both negative ions and ozone are not generated and treated with air at 0 ° C., the concentration of negative ions is about 10^FivePiece / cm^ThreeIn the case of treatment with ionized air at 0 ° C. with an ozone concentration of 0.002 ppm or less, and with an ozone concentration of about 0.2 ppm, a negative ion concentration of about 10²Piece / cm^ThreeThe case where it processed with the following ozonized air of 0 degreeC was added. The sampling of general bacteria on the surface of the sashimi 14 was performed by a stamp method, and a standard agar medium was used as the medium.
[0057]
As shown in Table 2, the experimental results show that when treated with air without generating ions and ozone, the number of bacterial colonies after 3 days is about 1600 / cm.² The negative ion concentration is about 10^Five Piece / cm^Three In the case of treatment with ionized air having an ozone concentration of 0.002 ppm or less, the number of bacterial colonies after 3 days is about 1000 / cm.² As a result, the growth of bacteria was slightly suppressed, but it was found that the effect was not so much.
[0058]
Also, the ozone concentration is about 0.2 ppm and the negative ion concentration is about 10² Piece / cm^Three When treated with the following ozonated air, the number of bacterial colonies after 3 days is about 600 / cm.² Thus, bacterial growth is significantly suppressed. However, when treated with ozone, the appearance of the sashimi sashimi turns red and black due to the strong oxidizing action of ozone, resulting in a problem that the quality is remarkably deteriorated.
[0059]
On the other hand, the temperature is 0 ° C. and the negative ion concentration is about 10^FivePiece / cm^ThreeWhen treated with ionized air 10 containing ozone with an ozone concentration of 0.05 ppm, the number of bacterial colonies after 3 days is about 300 / cm.² It became a petri dish and the effect that proliferation was suppressed considerably was acquired. In addition, even after 3 days of treatment, no change in appearance was observed, no rot odor was felt, and it was confirmed that the initial freshness could be completely maintained.
[0060]
As described above, according to the above experimental results, the sashimi is present on the surface of the ionized air containing low-concentration ozone and high-concentration negative ions without being discolored or altered like high-concentration ozone treatment. It can be seen that the propagation of microorganisms can be prevented and the initial freshness can be maintained.
[0061]
In the above embodiment, the ion concentration and the ozone concentration are kept constant during the treatment period. However, the ion frequency is set to a high concentration by changing the pulse frequency value during the treatment period. Even if only the ozone concentration is changed, and the continuous treatment is performed with ions and the intermittent treatment is performed with ozone, microbial growth is greater than continuous treatment with air 10 containing low-concentration ozone and high-concentration negative ions. Although the prevention effect is slightly reduced, almost the same effect can be obtained.
[0062]
Embodiment5.
  FIG. 8 shows an embodiment of the present invention.5In the figure, 36 is a gas flow control means, and in this case, the gas 1 is forced to flow into the space between the metal needle electrode 7 and the metal plate ground electrode 8, It is a gas flow direction control plate that narrows the cross section of the gas flow path and increases the flow velocity of the gas 1 flowing between the electrodes 7 and 8.
[0063]
Next, the operation will be described.
First, the fan 2 takes in the external gas 1 from the supply port 4 and guides it to the gas flow direction control plate 36 through the ventilation path 3.
The flow direction of the gas 1 guided to the gas flow direction control plate 36 is changed by the gas flow direction control plate 36, and a plurality of metal needle electrodes 7 provided in the ionization chamber 5, It is supplied to the discharge space between the metal flat plate ground electrodes 8 arranged facing each other. Here, when a negative DC pulse high voltage of several kV produced by the step-up converter 22 and pulsed by the pulse converter 23 is applied to the metal needle electrode 7, a high electric field is generated near the tip of the metal needle electrode 7. Corona discharge occurs.
[0064]
When the gas 1 containing oxygen molecules is introduced into the ionization chamber 5 during discharge, the oxygen molecules and the like contained in the gas 1 are attached to the electrons, thereby negatively ionizing the oxygen molecules and the like. When the molecule collides and dissociates with the electrons, ozone is generated, and an ionized gas 10 containing both ozone and negative ions is generated.
[0065]
In addition, as a result of investigating the relationship between the gas flow rate of the gas 1 flowing between both the metal needle electrode 7 and the metal plate ground electrode 8 and the generation amount of ozone and negative ions, the more negative the gas flow rate, the more negative the gas flow rate. It was confirmed that although the amount of ions generated increased, the amount of ozone generated did not change.
Therefore, by increasing the flow rate of the gas 1 flowing between the electrodes 7 and 8, it is possible to generate high-concentration negative ions in the gas 1 while suppressing the generation amount of ozone. I understand.
[0066]
  This embodiment5Is configured to suppress the current flowing during discharge, and the gas flow direction control plate 36 increases the flow velocity of the gas flowing between the metal needle electrode 7 and the metal plate ground electrode 8, so that the generation of ozone is prevented. While suppressing and maintaining the ozone concentration at a low concentration, the amount of negative ions generated can be increased more favorably, and an ionized gas containing a higher concentration of negative ions can be obtained.
  When the ionized gas 10 containing the low-concentration ozone and the high-concentration ions generated in this way is supplied to the object 14 on which the microorganisms are propagated, the synergistic effect of the ions and ozone is similar to the above embodiment. Controls the growth of microorganisms.
[0067]
The gas flow direction control plate 36 is preferably installed upstream of the ionization chamber 5 from the viewpoint of preventing disappearance due to collision of generated ions.
[0068]
Embodiment6.
  Embodiment above5In FIG. 9, the gas flow direction control plate 36 allows the gas 1 to flow into the discharge space between the metal needle electrode 7 and the metal flat plate ground electrode 8, but the schematic perspective view showing the ionization chamber 5 portion of FIG. As described above, in the ionization chamber 5, a plurality of fine metal wires 24 of about 0.1 to 0.2 mm and a metal grid-like ground electrode 25 arranged to face the fine metal wires 24 are provided. The same effect can be obtained by providing a gas flow direction control plate 36 on the upstream side of the gas so that the gas 1 flows only in the vicinity of the fine metal wire electrode 24 and the gas flow passage is narrowed to increase the flow velocity of the gas 1. It is done.
  Further, since the discharge electrode is made of a fine metal wire, the pressure loss when the gas 1 flows near the fine metal wire can be reduced, and there is an effect that a large amount of gas can be flown.
[0069]
Embodiment7.
  FIG. 10 shows an embodiment of the present invention.7In the figure, reference numeral 37 denotes an ozonolysis apparatus for decomposing ozone in the gas 1 that is installed in one air passage and is taken in by the fan 2. In the form, an ozone decomposition catalyst such as manganese dioxide or activated alumina is used. Reference numeral 38 is provided at the junction of one air passage and the other air passage, and controls the ratio of the flow rate of the gas 1 that passes through the ozonolysis device 37 to the flow rate of the gas 1 that does not pass and is taken into the ionization chamber 5. It is a gas flow rate control device that adjusts the ozone concentration in the gas. This ozone decomposition device and gas flow rate control device constitute an ozone concentration adjusting means.
[0070]
Next, the operation will be described.
First, the gas 1 that passes through the ozonolysis device 37 and the gas 1 that does not pass through the fan 2 and the gas flow rate control device 38 are mixed and taken in at a certain mixing ratio, and are introduced into the ionization chamber 5 through the air passage 3. It is burned.
In the ionization chamber 5, a plurality of metal needle electrodes 7 and a metal flat plate ground electrode 8 disposed to face the metal needle electrode 7 are spaced from each other (gap between the metal needle electrode 7 and the metal flat plate ground electrode 8). (Long) is provided at several mm. Here, when a negative DC pulse high voltage of several kV produced by the step-up converter 22 and pulsed by the pulse converter 23 is applied to the metal needle electrode 7, it is high near the tip of the metal needle electrode 7. An electric field is applied and corona discharge occurs.
[0071]
When the gas 1 containing oxygen molecules is introduced into the ionization chamber 5 during discharge, the oxygen molecules and the like contained in the gas 1 are attached to the electrons, thereby negatively ionizing the oxygen molecules and the like. As a result of collisional dissociation with electrons, ozone is generated, and the ionized gas 10 containing both ozone and negative ions is taken out.
[0072]
At this time, since the ozone concentration in the gas 1 sucked into the ionization chamber 5 is kept constant by the ozone decomposition device 37 and the gas flow rate control device 38, a certain amount of ozone is generated in the ionization chamber 5. The ionized gas 10 containing a constant concentration of ozone can be supplied to the object 14 on which microorganisms are propagated simply by making it occur.
This makes it easy to control the ozone concentration in the ionized gas 10 containing ozone supplied to the object 14 on which the microorganisms propagate, and can maintain ozone that is harmful when it reaches a high concentration in a low concentration range, which is safe and efficient. In particular, the growth of microorganisms can be prevented.
[0073]
Embodiment8.
  Embodiment above7In FIG. 11, the ozone concentration in the gas 1 sucked into the ionization chamber 5 is kept constant by the ozone decomposition device 37 and the gas flow rate control device 38. As shown in the configuration diagram of FIG. An ozone decomposing heating wire 39 is provided upstream of the ionization chamber 5, and the temperature of the ozone decomposing heating wire 39 is controlled to be constant so that ozone in the gas 1 is always decomposed by a certain amount. The same effect can be obtained even if the ozone concentration in the gas 1 sucked into the ionization chamber 5 is kept constant.
  Further, the number of parts can be reduced, the configuration of the apparatus is simple, and the control becomes easy.
[0074]
Embodiment9.
  FIG. 12 shows an embodiment of the present invention.94 is a configuration diagram showing a microbial growth prevention apparatus according to FIG. 1. In the figure, 40 is an ammeter for measuring a current value flowing into the metal needle electrode 7, 41 is an input signal from the ammeter 40, and is output to the boost converter 22. It is a control device that sends a signal.
[0075]
Next, the operation will be described.
First, the fan 2 takes in the external gas 1 from the supply port 4 and guides it into the ionization chamber 5 through the ventilation path 3.
In the ionization chamber 5, a plurality of metal needle electrodes 7 and a metal flat plate ground electrode 8 disposed to face the metal needle electrode 7 are spaced from each other (gap between the metal needle electrode 7 and the metal flat plate ground electrode 8). (Long) is provided at several mm. Here, when a negative DC pulse high voltage of several kV produced by the step-up converter 22 and pulsed by the pulse converter 23 is applied to the metal needle electrode 7, a high electric field is generated near the tip of the metal needle electrode 7. As a result, corona discharge occurs, and ionized gas 10 containing low-concentration ozone and negative ions is generated.
[0076]
In this embodiment, the current value flowing into the metal needle electrode 7 is measured by the ammeter 40 at this time. When it is recognized that the current value tends to increase, a signal is sent from the ammeter 40 to the control device 41, and a signal is sent from the control device 41 to the step-up converter 22 to be applied to the metal needle electrode 7. The voltage generated is reduced, the discharge current flowing during discharge is increased, and the generation amount of ozone can be prevented from increasing.
[0077]
In addition, by continuously measuring the increase / decrease in current with the ammeter 40, the degree of contamination of the electrode is monitored, so that the maintenance time of the metal needle electrode 7 can be easily known.
Furthermore, when an abnormal current flows, the application of a high voltage to the metal needle electrode 7 can be stopped, and a fire or the like can be prevented from occurring.
This makes it easy to control the ozone concentration in the ionized gas 10 containing ozone supplied to the object 14 on which the microorganisms propagate, and can maintain ozone that is harmful when it reaches a high concentration in a low concentration range, which is safe and efficient. In particular, the growth of microorganisms can be prevented.
[0078]
Embodiment10.
  Embodiment above9Then, the current value flowing into the metal needle electrode 7 is measured by the ammeter 40 and a signal is sent from the ammeter 40 to the step-up converter 22 via the control device 41 to reduce the voltage applied to the metal needle electrode 7. In this way, the ozone concentration in the gas 1 is maintained constant. As shown in the configuration diagram of FIG. 13, an ammeter 40 is provided between the metal plate ground electrode 8 and the ground. Even if the discharge current flowing between the electrodes 7 and 8 is measured, the same effect can be obtained.
  In addition, since the ammeter 40 is installed in a portion where a high voltage is not applied, it is not necessary to change the specification of the ammeter 40 to a high voltage specification, and there is an effect that the apparatus cost can be reduced.
[0079]
【The invention's effect】
  As described above, the active particle generation method of the present invention includes a pulse generator that intermittently supplies a voltage supplied to the active particle generation electrode, and controls the pulse frequency of the pulse generator,The ozone concentration is changed while keeping the ion concentration substantially constant, and ozone of 0.1 ppm or less and at least 10 ppm ^Four Piece / cm ^Three Of ozone concentrationWhile maintaining a low concentration rangeAn active particle generation method having a high ability to prevent the growth of microorganisms can be obtained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a microbial growth prevention apparatus according to a first embodiment of the present invention.
FIG. 2 is a characteristic diagram showing the relationship between the pulse frequency and the amount of negative ions and ozone generated according to Embodiment 1 of the present invention.
FIG. 3 is a configuration diagram showing a modification of the microbial growth preventing apparatus according to Embodiment 1 of the present invention.
FIG. 4 is a block diagram showing a microbial growth prevention apparatus according to Embodiment 2 of the present invention.
FIG. 5 is a circuit diagram showing a configuration of a pulse generator of a microbial growth prevention apparatus according to Embodiment 3 of the present invention.
FIG. 6 of the present inventionReference exampleIt is a block diagram which shows the microorganisms propagation prevention apparatus by JIS.
FIG. 7 shows an embodiment of the present invention.4It is a block diagram which shows the microorganisms propagation prevention apparatus by JIS.
FIG. 8 shows an embodiment of the present invention.5It is a block diagram which shows the microorganisms propagation prevention apparatus by JIS.
FIG. 9 shows an embodiment of the present invention.6It is a model perspective view which shows the ionization chamber part of the microbial growth prevention apparatus by JIS.
FIG. 10 shows an embodiment of the present invention.7It is a block diagram which shows the microorganisms propagation prevention apparatus by JIS.
FIG. 11 shows an embodiment of the present invention.8It is a block diagram which shows the microorganisms propagation prevention apparatus by JIS.
FIG. 12 shows an embodiment of the present invention.9It is a block diagram which shows the microorganisms propagation prevention apparatus by JIS.
FIG. 13 shows an embodiment of the present invention.10It is a block diagram which shows the microorganisms propagation prevention apparatus by JIS.
FIG. 14 is a block diagram showing a conventional microbial growth prevention apparatus.
[Explanation of symbols]
  DESCRIPTION OF SYMBOLS 1 Gas, 2 Fan, 3 Air flow path, 4 Supply port, 5 Ionization chamber, 7 Metal needle electrode, 8 Metal plate ground electrode, 9 Dielectric, 10 Ionized gas containing ozone, 14 objects, 21 Input power supply, 22 Boost conversion 23 Pulse converter 24 Metal fine wire electrode 25 Metal grid ground electrode 26 Rectifier 27 Capacitor 28 Pulse oscillator 29 Pulse transformer 30a-30d Resistor 31a-31d Diode 32a 32b Capacitor 33 Thyristor , 34 transformer, 35 ion supply chamber, 36 gas flow direction control plate, 37 ozone decomposition device, 38 gas flow rate control device, 39 heating wire for ozone decomposition, 40 ammeter, 41 control device.

Claims (2)

Active particle generation that ionizes and ozonizes a gas containing oxygen supplied by a fan to the active particle generation chamber by a discharge generated by applying a DC pulse voltage between the active particle generation electrodes arranged in the active particle generation chamber In this method, the pulse frequency of the direct-current pulse voltage is controlled while keeping the gas flow rate constant, the ozone concentration is controlled while keeping the ion concentration substantially constant, and ozone of 0.1 ppm or less and at least 10 ⁴ A method for generating active particles, comprising generating a gas containing ions / cm ³ ions. Active particles generating method according to claim 1, wherein the generating many 0.1ppm or less ozone than 0.002ppm a gas containing at least 10 ⁴ / cm ³ ions.

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