JP2004141745A - Apparatus and method for discharging fluid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for discharging a fluid, which are used in a production process of electronic parts, household electric appliances or the like and by which the discharge of each of various kinds of powder and various fluids such as an adhesive, creamy solder, a phosphor, grease, paint, a hotmelt, a chemical, food can be blocked/started at a high speed without compressing/pulverizing the powder. <P>SOLUTION: An application apparatus being this fluid discharging apparatus is constituted so that relatively different linear motions and relatively different rotatory motions are given respectively to a shaft and a cylinder, the fluid is conveyed by the relatively different rotatory motions and the discharge amount of the fluid is controlled by lessening/enlarging the gap to be formed between the fixed side and the rotating side by using the relatively different linear motions. A shape of a forcibly sending groove and that of a sealing groove are decided so that when the gap is small, the fluid can be discharged by making effective use of the forcibly sending groove and when the gap is large, the fluid can be blocked by making effective use of the sealing groove. As a result, the discharge of the fluid can be blocked/started at a high speed with high precision. <P>COPYRIGHT: (C)2004,JPO

Description

【００３９】
（１）式の右辺でＰｉが負なのは、内周側グルーブ６０のグルーブ角度が外周側と比べて１８０度位相が異なっており、流体のポンピング方向が逆だからである。
【００４０】
図３から、隙間ｈ＜１０μｍの範囲ではＰｓ＞０であり、図４（イ）のごとく、流体は吐出ノズル５６から吐出する。吐出ノズル５６の流体抵抗をＲｎとすれば、吐出量Ｑ＝Ｐｓ／Ｒｎである。従って、吐出流量Ｑは圧力Ｐｓにより、すなわち、０＜ｈ＜１０μｍの区間での隙間ｈの設定により調節することができる。一方、隙間ｈ＞１０μｍの範囲ではＰｓ＜０であり、図４（ロ）のごとく流体は吐出ノズル６からの流出は遮断される。
【００４１】
本発明が、前述した特開２００２−００１１９２号公報に記載された技術と異なるのは、性格の異なる２つの動圧グルーブの組み合わせにより、対向面の隙間を近接させたときに吐出を開放し、逆に離反させたときには吐出を遮断するという点である。
【００４２】
この方法を利用して連続塗布を行えば、２つの対向面間にスクイーズ作用と、動圧シール作用の両方を得ることができ、その相乗効果により極めて切れ味のよい塗布線の始終端制御することが可能である。
【００４３】
図５は、軸方向駆動手段による隙間ｈの変位入力波形の一例、図６は図５の変位入力波形を与えたときの上流側６１の箇所における圧力特性を示す。この変位入力波形を用いて、「吐出流体の急峻な遮断」、「遮断状態の継続的維持」、「すみやかな吐出開始」を実現することができる。
【００４４】
▲１▼ｔ＝ｔ_１が吐出遮断のタイミングであり、隙間をｈ＝５→２０μｍに増大させる。隙間増大による逆スクイーズ効果によって、２つの対抗面の間には大きな負圧が瞬時にして発生するため、流体の吐出は急峻に遮断される。
【００４５】
▲２▼隙間がｈ＝２０μｍに到達すると、逆スクイーズ効果による圧力発生は無くなるが、内周側動圧グルーブ６０の作用によって、流体は遠心方向にポンピング作用を受けて、吐出ノズル内部の流体は逆流を始める。
【００４６】
▲３▼ｔ＝ｔ_２で隙間ｈ＝２０→１０μｍに小さくなると、図３のグラフから、動圧シールのポンピング圧力は、大気圧Ｐ＝０ＭＰａ（ゲージ圧）を保つことになる。
【００４７】
Ｐ＝０ＭＰａの状態は継続的に維持されるために、吐出ノズル５６内部の流体の流動はなくなり、流体が遮断された状態は任意の時間保つことができる。
【００４８】
また、吐出ノズル内部の大気に接した流体のメニスカスは不動の状態を保つことになる。
【００４９】
▲４▼吐出再開のｔ＝ｔ_３では、比較的穏やかにピストンを下降させ、隙間ｈ＝１０→５μｍに小さくする。
【００５０】
上記▲２▼の段階で、内周側グルーブ６０の遠心方向のポンピング作用により、吐出ノズル５６の先端近傍の流通路には空隙部が形成されている。そのため、隙間ｈ＝１０→５μｍによって発生する適度な正のスクイーズ圧力は、描画線をスムーズに描き始めるのに有効である。
【００５１】
【表１】

【００５２】
さて、粘性流体が充填された２つの対抗面間を急峻に近接させる、或いは、離すことによって生じるスクイーズ圧力について少し補足する。流体軸受の動圧効果のひとつとして知られるスクイーズ圧力は次式で表すことができる。
【００５３】
【数２】

【００５４】
（２）式において、μは流体の粘性係数、ｈは２つの対抗面間の距離、ｄｈ／ｄｔはｈの微分（速度）、ｒ_０は２つの対抗面の外径、ｒ_ｉは２つの対抗面に例えば吐出ノズルが形成されている場合は内径である。
【００５５】
図７は、時間に対する２つの対抗面間の隙間、図８は時間に対するスクイーズ圧力特性を示すグラフである。ｔ＝ｔ_１で隙間を小さくすると、正のピーク圧が発生する。（２）式からわかるように、圧力の発生区間は隙間が変化している間だけである。ｔ＝ｔ_２で隙間を増大すると、負のピーク圧（逆スクイーズ効果）が発生する。
【００５６】
特開２００２−００１１９２号公報に開示された技術のごとく、流体を遮断するために動圧シールを形成した２つの対抗面を近接させると、正のスクイーズ圧力が発生する。したがって、流体の遮断時には流量が過剰となり、描画線に流体塊ができる不具合となる。逆に流体を開放させるために、２つの対抗面間の隙間を増大させると、負のスクイーズ効果が発生する。実験の結果、この負圧は始点における描画線の欠落、細りになることがわかった。
【００５７】
前述したように、ニードルバルブを構成する細径のスプールを軸方向に高速で移動させることにより、吐出口を開閉させる従来ディスペンサーの場合でも課題は同様である。
【００５８】
本発明はこの点を根底から解決するもので、性格の異なる２つの動圧グルーブの組み合わせにより、上記例とは逆に、対抗面の隙間を近接させたときに吐出を開放し、隙間を増大させたときには吐出を遮断するという点を利用している。つまり本発明では、スクイーズ圧力と動圧シールは開放時には同時に正の圧力が発生し、また遮断時には同時に負の圧力が発生する。
【００５９】
圧力発生のレスポンスは、通常スクイーズ効果の方がはるかに高く、例えば、遮断時には負のスクイーズ圧力によって瞬時に流体が遮断される。負のスクイーズ圧力が有効な区間はピストンが上昇しているときだけであるが、ほどなくしてレスポンスの遅い動圧シールが遮断を継続する。かつ動圧シールの場合、スクイーズ効果を利用する場合と異なり、遮断状態を継続して維持することができる。
【００６０】
以下、本発明を電子部品の表面実装用ディスペンサーに適用した第１の実施形態について、図９を用いて説明する。
【００６１】
図９において、１は第１のアクチュエータであり、本実施形態では、高粘度流体を高速で間欠的に微小量かつ高精度に供給するために、高い位置決め精度が得られ、高い応答性を持つと共に大きな発生荷重が得られる超磁歪素子を用いた。
【００６２】
２は第１のアクチュエータ１によって駆動される中心軸である。第１のアクチュエータ１は、ハウジング３に収納されている。このハウジング３の下端部に配置されたハウジング４に、フロント側主軸５が回転自在かつ軸方向に微少移動可能に支持されている。６はフロント側主軸５とボルト７により、着脱自在にとりつけられ、シリンダ８に収納されたピストン（軸）、９はピストン６の吐出側端面とその対向面の間に形成されたスラスト流量制御部である。
【００６３】
このスラスト流量制御部に、図１で示した内周側グルーブと外周側グルーブが形成されている（図示せず）。
【００６４】
１０は流体シール、１１はピストン６とシリンダ８内面間の隙間で吸入側と吐出側を繋ぐ流通路である。シリンダ８には、ポンプ室１１と連絡する吸入口１２が形成されている。１３はシリンダ８の下端部に装着された吐出ノズルであり、１４はこの吐出ノズル１３を含む後述する吐出部である。
【００６５】
１５は第２のアクチュエータであり、ピストン６とシリンダ８の間に相対的な回転運動を与えるものである。モータロータ１６はリア側主軸１７に固着され、またモータステータ１８はハウジング１９に収納されている。
【００６６】
２０は超磁歪素子から構成される円筒形状の超磁歪ロッド、２１は超磁歪ロッド１６の長手方向に磁界を与えるための磁界コイルである。２２、２３は超磁歪ロッド２０にバイアス磁界を与えるための永久磁石ａ，ｂであり、超磁歪ロッド２０を中間に矜持する形で配置されている。
【００６７】
この永久磁石２２，２３は、超磁歪ロッド２０に予め磁界をかけて磁界の動作点を高めるもので、この磁気バイアスにより磁界の強さに対する超磁歪の線形性が改善できる。２４は超磁歪ロッド２０のリア側に配置され、かつリア側主軸１７と一体化した磁気回路のリア側ヨークである。前述したフロント側主軸５も、磁気回路のヨーク材も兼ねており、超磁歪ロッド２０のフロント側に配置されている。２５は磁界コイル２１の外周部に配置された円筒形状のヨーク材である。
【００６８】
２０→２２→２４→２５→５→２３→２０により、超磁歪ロッド２０の伸縮を制御する閉ループ磁気回路を形成している。なお、中心軸２はこの磁気回路に影響を与えないように、非磁性材料を用いている。すなわち、超磁歪ロッド２０、永久磁石２２，２３、磁界コイル２１により、磁界コイルに与える電流で超磁歪ロッドの軸方向の伸縮を制御できる超磁歪アクチュエータ（第１のアクチュエータ１）を構成している。
【００６９】
超磁歪材料は希土類元素と鉄の合金であり、例えばｂＦｅ_２，ＤｙＦｅ_２，ＳｍＦｅ_２などが知られおり、近年急速に実用化が進められている。上部中心軸１７は軸受２６により、ハウジング２７に対して回転自在に支持されている。
【００７０】
２８はフロント側主軸５と軸受スリーブ２９の間に装着されたバイアスバネである。この軸受スリーブ２９もまたハウジング４に対して、軸受３０によって回転自在に支持されている。バイアスバネ２８から加わる軸方向荷重により、超磁歪ロッド２０はバイアス永久磁石２２，２３を介在して、上下の部材５、２４に押圧される形で把持されている。この結果、超磁歪ロッド２０には常に軸方向に圧縮応力が加わるため、繰り返し応力が発生した場合に、引っ張り応力に弱い超磁歪素子の欠点が解消される。
【００７１】
ピストン６と一体化したフロント側主軸５は、軸受３０によって規制された軸受スリーブ２９に対して、軸方向に移動可能に収納している。
【００７２】
モータ１５から伝達された中心軸２の回転動力は、中心軸２とフロント側主軸５の間に設けられた回転伝達キー３１によって、フロント側主軸５に伝達される。この回転伝達キー３１は、回転動力は伝達するが、軸方向にはフリーとなるような角型の断面形状となっている（図示せず）。
【００７３】
上記構成により、モータ１５の回転動力は中心軸２とフロント側５のみに伝達され、脆性材料である超磁歪素子に捻りトルクは発生しない。３２は第２のアクチュエータであるモータ１５の上部に配置された上部中心軸１７の回転位置情報を検出するためのエンコーダである。
【００７４】
また、３３，３４はフロント側５（およびピストン６）の軸方向変位を検出するための変位センサーＡ及び変位センサーＢである。
【００７５】
上記構成により、本発明の流体塗布装置では、ポンプのピストン６は回転運動と微少変位の直線運動の制御を同時に、かつ独立して行うことができる。
【００７６】
更に、本実施形態では、第１のアクチュエータに超磁歪素子を用いたために、超磁歪ロッド２０（及びピストン６）を直線運動させるための動力を、外部から非接触で与えることができる。
【００７７】
超磁歪素子に加えた入力電流と変位は比例するため、変位センサーなしのオープンループ制御でも、前記ピストン６の軸方向位置決め制御は可能である。しかし本実施例のような位置検出手段を設けてフィードバック制御をすれば、超磁歪素子のヒステリシス特性も改善できるため、より高い精度の位置決めができる。
【００７８】
なお、内周側グルーブ（図１の６０）と外周側グルーブ（図１の５９）は、個別にはスラスト動圧軸受として知られているものである。これらスラスト軸受の隙間に対する圧力特性は、回転角速度、スラスト軸受の内外径、溝深さ、溝角度、グルーブ幅とリッジ幅の比などで決定される。
【００７９】
本実施形態では、外周側グルーブは隙間の変化に対して発生圧力の変化が鋭敏な特性Ａを有し、内周側グルーブは隙間の変化に対して発生圧力の変化が鈍感な特性Ｂを有するが、このＡとＢの配置方法は逆でもよい。
【００８０】
また、本実施形態では、溝深さと内外径の大きさの違いで特性Ａ，Ｂを選択したが、どのようなパラメータでＡとＢの特性を選択してもよい。また動圧溝を形成する面はピストン側、その対向面のいずれでもよい。
【００８１】
また、内周側グルーブと外周側グルーブを形成する２つの対向面の形状は、平面でなくてもよく、球面或いは円錐面などでもよい。
【００８２】
流体の遮断時、吐出ノズルの開口部６１近傍の流体は、内周側グルーブ６０の作用によって遠心方向のポンピング作用（図４の（ロ）の矢印）を受けているために、開口部６１近傍は負圧（大気圧以下）となる。この効果により、遮断後、吐出ノズル５６内部に残存していた流体は再びポンプ内部に吸引される。
【００８３】
その結果、吐出ノズル先端で表面張力による流体塊ができることはなく、糸引き、洟垂れが解消されるのである。本発明では、ポンプ内部への流体の吸引の度合いは、隙間ｈの設定により微妙に調整できるため、吸引過ぎることのない適度な状態を設定することができる。
【００８４】
また、微少粒子が含まれた接着剤のような粉流体を塗布する場合は、ギャップδの最小値δｍｉｎは微少粒子径φｄよりも大きく設定すればよい。
【００８５】
【数３】

【００８６】
より大きなギャップを得るためには、ピストンの外径を大きくかつ溝深さ、溝角度等に適切な値を選べば良い。或いは、動圧溝を形成した円筒形状のツバを設けてもよい。
【００８７】
本実施形態では、圧送溝、シール溝をピストンのスラスト端面のみに形成したが、いずれかの溝のポンピング作用を補助する溝をピストン軸の円周面あるいはその対向面に形成してもよい。
【００８８】
軸方向駆動手段としては、ムービングマグネットなどのリニアモータ、電磁ソレノイド等を用いることができる。本実施例では、軸方向駆動手段に超磁歪素子を用いたが、微少流量を扱うポンプでは、「非接触シール」を構成するためのギャップδのストロークは数十ミクロンのオーダでよく、超磁歪素子、ピエゾ素子などの電磁歪素子のストロークの限界は問題とならなかった。
【００８９】
また、高粘度流体を吐出させる場合、スクイーズ作用によって大きな吐出圧の発生が予想される。この場合、第１のアクチュエータ１には高い流体圧に抗する大きな推力が要求されるため、数百〜数千Ｎの力が容易に出せる電磁歪型アクチュエータが好ましい。電磁歪素子は、数ＭＨｚ以上の周波数応答性を持っているため、主軸を高い応答性で直線運動させることができる。そのため、高粘度流体の吐出量を高いレスポンスで高精度に制御できる。
【００９０】
また、軸方向駆動手段に超磁歪素子を用いた場合、圧電素子を用いる場合と比べて、伝導ブラシも省略できることから、モータ（回転手段）の負荷を軽減できると共に、全体構成が極めてシンプルとなるため、稼動部の慣性モーメントを極力小さくでき、ディスペンサーの細径化が可能である。
【００９１】
本実施形態では、ピストンとハウジングを相対的に回転させながら、軸方向駆動手段によって、両部材を相対的に軸方向に移動させる構成にした。すなわち、この場合、ピストンはモータと超磁歪素子で構成される２自由度アクチュエータにより駆動される。
【００９２】
本実施形態のような２自由度アクチュエータではなく、軸方向駆動手段と回転手段は個別に構成してもよい。例えば、特開２００２−１４３７４５号公報に記載された技術のように、ピストンはモータによって回転のみを与えて、固定側に設けられた圧電素子などのアクチュエータでピストン端面間の隙間を制御してもよい。
【００９３】
本実施形態では、ピストンは１軸の構成であったが、前述した特開２００２−００１１９２号公報に記載された技術のように、２重ピストンの構成でもよい。この場合、ピストンとこのピストンを収納するスリーブのいずれの端面（或いはその対向面）に外周側グルーブと内周側グルーブを形成してもよい。或いは、スリーブ側だけに外周側グルーブと内周側グルーブをセットで形成してもよい。
【００９４】
【発明の効果】
本発明を用いた流体回転装置により、次の効果が得られる。
１．高速吐出遮断と開始ができる。
２．粉体の圧搾破損による流路の詰まり、流体の特性変化などのトラブルが発生しない。
３．更に以下示す特徴を、本発明のポンプは合わせ持つことができる。
【００９５】
▲１▼高粘度流体の高速塗布ができる。
【００９６】
▲２▼超微少量を高精度で吐出できる。
【００９７】
本発明を、例えば表面実装のディスペンサー、ＰＤＰ，ＣＲＴディスプレイの蛍光体塗布、液晶パネルのシール材塗布等に用いれば、その長所をいかんなく発揮でき、効果は絶大なものがある。
【図面の簡単な説明】
【図１】本発明の原理を示すモデル図
【図２】２つの動圧溝の発生圧力と隙間の関係の解析結果を示す図
【図３】２つの動圧溝を合成した場合の発生圧力と隙間の関係を示す図
【図４】ピストン端面部の流体の流動状態を示し、（イ）は隙間が小、（ロ）は隙間が大のときを示すモデル図
【図５】ピストン端面部の隙間と時間の関係を示す図
【図６】発生圧力と時間の関係を示す図
【図７】ピストン端面部の隙間と時間の関係を示す図
【図８】スクイーズ圧力と時間の関係を示す図
【図９】本発明の具体的に実施の形態であるディスペンサーの正面断面図
【図１０】従来のエアー式ディスペンサーの正面断面図
【符号の説明】
５１　軸
５２　ハウジング
６３　ポンプ室
５５　吸入口
５６　吐出口
５４　回転させる手段
５３　軸方向駆動手段
５９　圧送溝
６０　シール溝[0001]
TECHNICAL FIELD OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention can be used in production processes in the fields of electronic components and home electric appliances, and discharges / discharges various liquids such as adhesives, cream solders, phosphors, greases, paints, hot melts, chemicals, and foods in a fixed amount. And a fluid discharge method for the same.
[0002]
[Prior art]
Liquid ejecting devices (dispensers) have been used in various fields, but with the recent demand for miniaturization and high recording density of electronic components, a small amount of fluid material can be dispensed with high accuracy and stability. There is a demand for a technique for controlling discharge. Taking the field of surface mounting (SMT) as an example, in the trend of high-speed mounting, miniaturization, high-density, high-quality, and unmanned, the issues of dispensers can be summarized as follows:
(1) High accuracy of coating amount and miniaturization of one coating amount
(2) Discharge time can be shortened, that is, high-speed discharge can be cut off and started
(3) Capable of handling high-viscosity powder fluids
It is. Conventionally, in order to discharge a liquid at a very small flow rate, dispensers such as an air pulse method, a screw groove method, and a micro pump method using an electromagnetic strain element have been put to practical use.
[0003]
[Patent Document 1]
JP 2002-001192 A
[Patent Document 2]
JP-A-2002-143745
[0004]
[Problems to be solved by the invention]
Among the above-mentioned conventional techniques, a dispenser using an air pulse method as shown in FIG. 10 is widely used, and the technique is introduced in, for example, "Automation Technology '93 .25 Vol. 7". A dispenser according to this method applies a constant amount of air supplied from a constant pressure source to a pulse in a container (cylinder) 200 and discharges a fixed amount of liquid from the nozzle 201 corresponding to an increase in the pressure in the cylinder 200. It is.
[0005]
However, this air pulse type dispenser has a drawback that response is poor. This drawback is due to the compressibility of the air 202 enclosed in the cylinder and the nozzle resistance when passing air pulses through a narrow gap.
[0006]
That is, in the case of the air pulse method, the time constant T = RC of the fluid circuit determined by the volume C of the cylinder and the nozzle resistance R is large, and for example, about 0.07 to 0.1 seconds after the input pulse is applied to start the discharge. We have to expect a delay.
[0007]
In the field of circuit formation described above, or in the fields of forming electrodes and ribs for picture tubes such as PDPs and CRTs, applying sealing materials for liquid crystal panels, and manufacturing processes for optical discs, etc., in addition to the above (1) to (3), There are strong demands for fine coating technology as follows.
[0008]
(4) I want to stop coating quickly at any timing after continuous spraying. I want to start the continuous coating rapidly after a shorter time. For that purpose, it is ideal that the flow rate can be controlled, for example, on the order of 0.01 seconds.
[0009]
{Circle around (5)} In the above {circle around (4)}, there is no thinning, breakage or generation of a fluid mass at the start point of the drawing line.
[0010]
In the case of the air method, the start and end can often be corrected by means of software that applies an air pulse. However, poor responsiveness is fatal and poses a substantial challenge in terms of production tact.
[0011]
To eliminate the drawbacks of the air pulse method, a needle valve is provided at the inlet of the discharge nozzle, and the discharge port is opened and closed by moving a small-diameter spool constituting the needle valve at a high speed in the axial direction. Dispensers have been put to practical use. When the discharge is opened / closed using a needle valve, there are the following problems.
[0012]
At the time of opening, a negative pressure is generated when the needle-like portion (convex portion) of the spool is detached from the concave portion that accommodates the convex portion, and as a result, the start of ejection is delayed. This tendency is more remarkable in the case of a high-viscosity fluid, and the starting point becomes thin or cut when drawing a drawing line. At the time of interruption, there was a problem that a fluid mass was formed at the end point of the drawing line due to the generation of the positive pressure.
[0013]
In the case of the needle valve system, when the fluid is shut off, the gap between the relatively moving members becomes zero, and the powder having an average particle diameter of several to several tens of microns is mechanically pressed and destroyed. Due to various inconveniences that occur as a result, it is often difficult to apply the method to application of an adhesive, a conductive paste, or a phosphor mixed with powder.
[0014]
For the same purpose, a screw groove type dispenser which is a viscous pump has already been put to practical use. In the case of the screw groove type, a pump characteristic which is hardly dependent on the nozzle resistance can be selected, so that a preferable result can be obtained in the case of continuous application, but the intermittent application is not good in terms of the characteristics of the viscous pump. Therefore, in the conventional screw groove type,
(1) An electromagnetic clutch is interposed between the motor and the pump shaft, and this electromagnetic clutch is connected or released at the time of discharge ON / OFF.
[0015]
(2) Use a DC servomotor to start or stop rapid rotation.
[0016]
However, since the response is determined by the time constant of the mechanical system in any of the above cases, the high-speed intermittent operation is limited. The responsiveness is better than that of the air pulse method, but the limit is about 0.05 seconds even in the shortest time.
[0017]
In addition, since there are many uncertainties in the rotational characteristics of the pump shaft during transient response (at the start and stop of rotation), it is difficult to strictly control the flow rate, and the coating accuracy per dot is limited. Even when a continuous line is drawn at a high speed using this screw groove type, it is difficult to draw the start and end of the drawn line with high quality.
[0018]
In order to respond to various recent demands related to the above-described minute flow rate application of a high-viscosity fluid / powder fluid, the present inventors have proposed a piston and a cylinder as disclosed in JP-A-2002-001192. Between the fixed side and the rotating shaft side using linear motion to change the relative gap between the fixed side and the rotating shaft side. A coating means for controlling the shutoff / release of fluid by a thrust dynamic pressure seal formed on the surface has been proposed.
[0019]
Further, the present inventors have disclosed in Japanese Patent Application Laid-Open No. 2002-001192 that the piston has a double structure having two output shafts, and that the two output shafts are driven in opposite phases at the start and end, so that the piston A method for eliminating the change in the volume of the end face and the change in the pressure accompanying the change in the volume is proposed.
[0020]
The present invention solves the problem of starting and ending with a simpler configuration than the above proposal. That is, two dynamic pressure grooves are combined to form a dynamic pressure seal. Contrary to the conventional technology, when the thrust surface and the opposing surface are brought close to each other, the fluid is released, and when the thrust surface is separated from the thrust surface, the fluid is released. The dynamic pressure seal is provided with a "pressure characteristic with respect to the gap" so that it can be shut off.
[0021]
With this configuration, it is possible to simultaneously utilize both the squeeze effect and the dynamic pressure sealing effect at the start or end of the application, and it is possible to realize extremely accurate start / end control of the application line.
[0022]
[Means for Solving the Problems]
The fluid ejection device according to the first aspect of the present invention includes a means for relatively rotating a shaft and a housing for housing the shaft, an axial driving means for varying a gap between an end surface of the shaft and an opposing surface thereof, And a fluid discharge device comprising a fluid suction port and a fluid discharge port communicating the outside with a pump chamber formed by the housing, wherein the pump is formed on a relative movement surface between an end surface of the shaft and a facing surface thereof. When the gap is small, it is composed of a pumping groove for pumping the fluid flowing into the chamber toward the discharge port side, and a seal groove formed on the relative moving surface and for pumping the fluid in a direction opposite to the pumping groove. The pumping groove and the seal groove are formed such that the fluid is shut off when the pumping groove discharges a fluid and the gap is large.
[0023]
At this time, it is preferable that each of the pressure feed groove and the seal groove is formed on either the outer peripheral side or the inner peripheral side of the relative movement surface.
[0024]
It is preferable that the pressure feeding groove is formed on the outer peripheral side of the relative moving surface and the seal groove is formed on the inner peripheral side.
[0025]
Further, it is preferable that the groove depth of the seal groove is larger than that of the pressure feeding groove.
[0026]
In the second fluid discharge method of the present invention, when the gap between the relative moving surfaces is large, the fluid pumping action of the seal groove acts, and when the gap is small, the fluid pumping action of the fluid by the pumping groove acts. The seal groove and the pressure feed groove are formed on the relative moving surface, and when the fluid is released, the gap is narrowed, so that the fluid flows out of the discharge port by the pressure feed groove, and when the fluid is shut off, the seal groove serves as the seal groove. It is characterized in that the action of causing the fluid to flow in the direction opposite to the discharge port is given to the fluid, and the discharge is interrupted.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
[1] Model diagram showing the principle of the present invention
FIG. 1 is a model diagram showing the principle of the present invention.
[0028]
In FIG. 1, reference numeral 51 denotes a piston, which is housed movably in an axial direction and a rotational direction with respect to a fixed housing. The piston 51 is driven by an axial drive means (arrow 53) and a rotational drive means (arrow 54). 55 is a fluid suction port formed in the housing, and 56 is a discharge nozzle.
[0029]
Further, 57 is an end face of the piston, and 58 is an opposing face thereof. Reference numeral 59 denotes an outer peripheral side thrust groove (pressure feeding groove) formed on a relative movement surface between the piston end surface 57 and the opposing surface 58, and reference numeral 60 denotes an inner peripheral side thrust groove (seal groove). Both black portions indicate the grooves of the dynamic pressure groove, and white portions indicate the peaks.
[0030]
An axial driving means 53 (specific structure is not shown) is provided between the piston 51 and the housing 52, and changes the relative position in the axial direction between the two members 51, 52. The gap h between the piston end face 57 and the opposing face 58 can be changed by the axial driving means 53. Incidentally, the generated pressure Ps of the dynamic pressure groove indicates a value of 61 points on the upstream side of the discharge nozzle 56. 62 is a coating fluid supplied between the piston 51 and the housing 52, and 63 is a pump chamber formed by the piston 51 and the housing 52.
[0031]
[2] About the principle of the present invention
The present invention combines two dynamic pressure type viscous pumps having different "generated pressure characteristics with respect to the gap",
{Circle around (1)} When the gap h is reduced, the outer peripheral side thrust groove (pressure feeding groove) 59 mainly works effectively, and the fluid is moved in the centripetal direction to perform discharge.
[0032]
{Circle around (2)} Conversely, when the gap h is increased, the inner circumferential thrust groove (seal groove) 60 mainly works effectively, and the function of moving the fluid in the centrifugal direction works, so that the fluid is shut off.
[0033]
The above (1) and (2) are realized by controlling the distance between the opposing surfaces while relatively rotating the two opposing surfaces forming the dynamic pressure groove.
[0034]
FIG. 2 is an analysis result obtained by obtaining the relationship between the generated pressure of the thrust dynamic pressure groove and the gap under the conditions shown in Table 1. FIG. 2A shows the characteristics of the outer circumferential groove, and FIG. 2B shows the characteristics of the inner circumferential groove.
[0035]
The outer circumferential groove is formed with a shallow groove depth of hg = 10 μm. Therefore, as the gap h becomes smaller, the generated pressure Po sharply increases. Conversely, when the gap h increases, the generated pressure Po decreases significantly. That is, in the outer circumferential groove, the change in the generated pressure is sharp with respect to the change in the gap, and an effective pressure is generated only in a small gap area.
[0036]
On the other hand, the inner peripheral groove is formed so that the groove depth is hg = 50 μm deeper than the outer peripheral groove. Therefore, the change in the generated pressure Pi is insensitive to the change in the gap h, and the absolute value of the generated pressure Pi is low even in an area where the gap is small. The magnitude of the pressure generated in both grooves is reversed at a gap h = 10 μm.
[0037]
FIG. 3 shows the relationship between the generated pressure Ps (the pressure on the upstream side 61 of the discharge nozzle) and the gap h when the two thrust dynamic pressure grooves are combined. When the generated pressure of the outer circumferential groove is Po and the generated pressure of the inner circumferential groove is Pi, the combined generated pressure Ps is
[0038]
(Equation 1)

[0039]
The reason why Pi is negative on the right side of the equation (1) is that the groove angle of the inner circumferential groove 60 is 180 degrees out of phase as compared with the outer circumferential groove, and the pumping direction of the fluid is opposite.
[0040]
From FIG. 3, Ps> 0 in the range of the gap h <10 μm, and the fluid is discharged from the discharge nozzle 56 as shown in FIG. Assuming that the fluid resistance of the discharge nozzle 56 is Rn, the discharge amount Q = Ps / Rn. Therefore, the discharge flow rate Q can be adjusted by the pressure Ps, that is, by setting the gap h in the section of 0 <h <10 μm. On the other hand, in the range of the gap h> 10 μm, Ps <0, and the fluid is prevented from flowing out from the discharge nozzle 6 as shown in FIG.
[0041]
The present invention is different from the technique described in the above-mentioned Japanese Patent Application Laid-Open No. 2002-001192 in that, by combining two dynamic pressure grooves having different characteristics, the discharge is opened when the gap between the opposing surfaces is brought close to each other. On the other hand, when they are separated, the ejection is cut off.
[0042]
If continuous application is performed using this method, both the squeezing action and the dynamic pressure sealing action can be obtained between the two opposing surfaces, and the start and end of the extremely sharp coating line can be controlled by the synergistic effect. Is possible.
[0043]
FIG. 5 shows an example of a displacement input waveform of the gap h by the axial driving means, and FIG. 6 shows a pressure characteristic at a location on the upstream side 61 when the displacement input waveform of FIG. 5 is given. By using this displacement input waveform, it is possible to realize "steep cutoff of the discharge fluid", "continuous maintenance of the cutoff state", and "swift discharge start".
[0044]
(1) t = t ₁ Is the timing of discharge interruption, and the gap is increased from h = 5 to 20 μm. Since a large negative pressure is instantaneously generated between the two opposing surfaces due to the reverse squeeze effect due to the increase in the gap, the discharge of the fluid is sharply shut off.
[0045]
{Circle around (2)} When the gap reaches h = 20 μm, pressure generation due to the reverse squeeze effect is eliminated, but the fluid is subjected to a pumping action in the centrifugal direction by the action of the inner peripheral side dynamic pressure groove 60, and the fluid inside the discharge nozzle is Start reflux.
[0046]
(3) t = t ₂ When the gap h is reduced from 20 to 10 μm, the pumping pressure of the dynamic pressure seal is maintained at the atmospheric pressure P = 0 MPa (gauge pressure) from the graph of FIG.
[0047]
Since the state of P = 0 MPa is continuously maintained, the fluid in the discharge nozzle 56 does not flow, and the state in which the fluid is shut off can be maintained for an arbitrary time.
[0048]
In addition, the meniscus of the fluid in contact with the atmosphere inside the discharge nozzle remains immobile.
[0049]
(4) t = t for resuming discharge ₃ Then, the piston is lowered relatively gently to reduce the gap h from 10 to 5 μm.
[0050]
In the step (2), a void is formed in the flow passage near the tip of the discharge nozzle 56 due to the centrifugal pumping action of the inner circumferential groove 60. Therefore, an appropriate positive squeeze pressure generated by the gap h = 10 → 5 μm is effective to start drawing a drawing line smoothly.
[0051]
[Table 1]

[0052]
Now, the squeeze pressure generated when the two opposing surfaces filled with the viscous fluid are brought into close proximity or separated from each other is supplemented a little. The squeeze pressure known as one of the dynamic pressure effects of the fluid bearing can be expressed by the following equation.
[0053]
(Equation 2)

[0054]
In the equation (2), μ is the viscosity coefficient of the fluid, h is the distance between the two opposing surfaces, dh / dt is the derivative (speed) of h, r ₀ Is the outer diameter of the two opposing faces, r _i Is the inner diameter when, for example, a discharge nozzle is formed on the two opposing surfaces.
[0055]
FIG. 7 is a graph illustrating a gap between two opposing surfaces with respect to time, and FIG. 8 is a graph illustrating a squeeze pressure characteristic with respect to time. t = t ₁ , A positive peak pressure is generated. As can be seen from the equation (2), the pressure is generated only during the period when the gap is changing. t = t ₂ When the gap is increased by the above, a negative peak pressure (reverse squeeze effect) occurs.
[0056]
As in the technique disclosed in Japanese Patent Application Laid-Open No. 2002-001192, when two opposing surfaces on which a dynamic pressure seal is formed are brought close to each other to block fluid, a positive squeeze pressure is generated. Therefore, when the fluid is shut off, the flow rate becomes excessive, which causes a problem that a fluid mass is formed on the drawing line. Conversely, increasing the gap between the two opposing surfaces to release the fluid will cause a negative squeeze effect. As a result of the experiment, it was found that this negative pressure caused the drawing line to be missing or thin at the starting point.
[0057]
As described above, the problem is the same in a conventional dispenser that opens and closes a discharge port by moving a small-diameter spool constituting a needle valve at a high speed in an axial direction.
[0058]
The present invention solves this point fundamentally, and by combining two dynamic pressure grooves having different characteristics, contrary to the above example, when the gap between the opposing surfaces is made closer, the discharge is opened and the gap is increased. Utilizing the fact that the discharge is interrupted when it is performed. That is, in the present invention, the squeeze pressure and the dynamic pressure seal generate a positive pressure at the same time when they are opened, and generate a negative pressure at the same time when they are shut off.
[0059]
The response of pressure generation is usually much higher in the squeeze effect, for example, when shutting off, the fluid is instantaneously shut off by a negative squeeze pressure. The section where the negative squeeze pressure is effective is only when the piston is rising, but soon the dynamic pressure seal with a slow response continues to shut off. Moreover, in the case of the dynamic pressure seal, unlike the case where the squeeze effect is used, the cutoff state can be continuously maintained.
[0060]
Hereinafter, a first embodiment in which the present invention is applied to a dispenser for surface mounting electronic components will be described with reference to FIG.
[0061]
In FIG. 9, reference numeral 1 denotes a first actuator. In this embodiment, high-precision fluid is supplied intermittently in a minute amount and with high precision at a high speed, so that high positioning accuracy is obtained and high responsiveness is obtained. In addition, a giant magnetostrictive element capable of obtaining a large generated load was used.
[0062]
Reference numeral 2 denotes a central axis driven by the first actuator 1. The first actuator 1 is housed in a housing 3. A front-side main shaft 5 is supported by a housing 4 arranged at the lower end of the housing 3 so as to be rotatable and slightly movable in the axial direction. Reference numeral 6 denotes a piston (shaft) detachably mounted by a front-side main shaft 5 and bolts 7 and housed in a cylinder 8, and 9 denotes a thrust flow control unit formed between the discharge-side end surface of the piston 6 and its facing surface. It is.
[0063]
The inner circumferential groove and the outer circumferential groove shown in FIG. 1 are formed in the thrust flow control unit (not shown).
[0064]
Reference numeral 10 denotes a fluid seal, and reference numeral 11 denotes a flow passage connecting the suction side and the discharge side with a gap between the piston 6 and the inner surface of the cylinder 8. The cylinder 8 has a suction port 12 communicating with the pump chamber 11. Reference numeral 13 denotes a discharge nozzle mounted on the lower end of the cylinder 8, and reference numeral 14 denotes a discharge unit including the discharge nozzle 13 and described later.
[0065]
Reference numeral 15 denotes a second actuator, which gives a relative rotational movement between the piston 6 and the cylinder 8. The motor rotor 16 is fixed to a rear main shaft 17, and the motor stator 18 is housed in a housing 19.
[0066]
Reference numeral 20 denotes a cylindrical giant magnetostrictive rod composed of giant magnetostrictive elements, and reference numeral 21 denotes a magnetic field coil for applying a magnetic field in the longitudinal direction of the giant magnetostrictive rod 16. Reference numerals 22 and 23 denote permanent magnets a and b for applying a bias magnetic field to the giant magnetostrictive rod 20, and are arranged in such a manner that the giant magnetostrictive rod 20 is held in the middle.
[0067]
The permanent magnets 22 and 23 apply a magnetic field to the giant magnetostrictive rod 20 in advance to increase the operating point of the magnetic field, and the magnetic bias can improve the linearity of the giant magnetostriction with respect to the strength of the magnetic field. Reference numeral 24 denotes a rear yoke of a magnetic circuit which is arranged on the rear side of the giant magnetostrictive rod 20 and is integrated with the rear main shaft 17. The front-side main shaft 5 also serves as a yoke material of the magnetic circuit, and is disposed on the front side of the giant magnetostrictive rod 20. Reference numeral 25 denotes a cylindrical yoke member arranged on the outer peripheral portion of the magnetic field coil 21.
[0068]
20 → 22 → 24 → 25 → 5 → 23 → 20 forms a closed loop magnetic circuit for controlling the expansion and contraction of the giant magnetostrictive rod 20. The center shaft 2 is made of a non-magnetic material so as not to affect the magnetic circuit. That is, the giant magnetostrictive rod 20, the permanent magnets 22 and 23, and the magnetic field coil 21 constitute a giant magnetostrictive actuator (first actuator 1) capable of controlling the expansion and contraction of the giant magnetostrictive rod in the axial direction by a current applied to the magnetic field coil. .
[0069]
The giant magnetostrictive material is an alloy of a rare earth element and iron, for example, bFe ₂ , DyFe ₂ , SmFe ₂ And the like, and practical use has been rapidly promoted in recent years. The upper center shaft 17 is rotatably supported by a housing 27 by a bearing 26.
[0070]
Reference numeral 28 denotes a bias spring mounted between the front-side main shaft 5 and the bearing sleeve 29. This bearing sleeve 29 is also rotatably supported by the housing 4 with respect to the housing 4. The giant magnetostrictive rod 20 is gripped by the upper and lower members 5 and 24 via the bias permanent magnets 22 and 23 by the axial load applied from the bias spring 28. As a result, the compressive stress is always applied to the giant magnetostrictive rod 20 in the axial direction, so that when a repetitive stress is generated, the defect of the giant magnetostrictive element which is weak in the tensile stress is solved.
[0071]
The front main shaft 5 integrated with the piston 6 is accommodated in the bearing sleeve 29 regulated by the bearing 30 so as to be movable in the axial direction.
[0072]
The rotational power of the central shaft 2 transmitted from the motor 15 is transmitted to the front main shaft 5 by a rotation transmission key 31 provided between the central shaft 2 and the front main shaft 5. The rotation transmission key 31 has a rectangular cross-sectional shape (not shown) that transmits rotational power but is free in the axial direction.
[0073]
With the above configuration, the rotational power of the motor 15 is transmitted only to the center shaft 2 and the front side 5, and no torsional torque is generated in the giant magnetostrictive element, which is a brittle material. Reference numeral 32 denotes an encoder for detecting the rotational position information of the upper central shaft 17 disposed above the motor 15 as the second actuator.
[0074]
Reference numerals 33 and 34 denote a displacement sensor A and a displacement sensor B for detecting an axial displacement of the front side 5 (and the piston 6).
[0075]
According to the above configuration, in the fluid application device of the present invention, the piston 6 of the pump can simultaneously and independently control the rotational movement and the linear movement with minute displacement.
[0076]
Further, in the present embodiment, since the giant magnetostrictive element is used for the first actuator, power for linearly moving the giant magnetostrictive rod 20 (and the piston 6) can be applied from outside without contact.
[0077]
Since the input current applied to the giant magnetostrictive element is proportional to the displacement, the axial positioning control of the piston 6 is possible even with open loop control without a displacement sensor. However, if feedback control is performed by providing the position detecting means as in the present embodiment, the hysteresis characteristics of the giant magnetostrictive element can be improved, and positioning with higher accuracy can be performed.
[0078]
The inner circumferential groove (60 in FIG. 1) and the outer circumferential groove (59 in FIG. 1) are individually known as thrust dynamic pressure bearings. The pressure characteristics of the thrust bearing with respect to the gap are determined by the rotational angular velocity, the inner and outer diameters of the thrust bearing, the groove depth, the groove angle, the ratio between the groove width and the ridge width, and the like.
[0079]
In the present embodiment, the outer circumferential groove has a characteristic A in which a change in generated pressure is sharp with respect to a change in the gap, and the inner circumferential groove has a characteristic B in which the change in generated pressure is insensitive to a change in the gap. However, the arrangement method of A and B may be reversed.
[0080]
In the present embodiment, the characteristics A and B are selected based on the difference between the groove depth and the size of the inner and outer diameters. However, the characteristics of A and B may be selected using any parameter. The surface on which the dynamic pressure groove is formed may be either the piston side or the opposing surface.
[0081]
Further, the shape of the two opposing surfaces forming the inner circumferential groove and the outer circumferential groove may not be a flat surface, but may be a spherical surface or a conical surface.
[0082]
When the fluid is shut off, the fluid near the opening 61 of the discharge nozzle is subjected to the centrifugal pumping action (arrow (b) in FIG. 4) by the action of the inner circumferential groove 60, so that the fluid near the opening 61. Becomes negative pressure (atmospheric pressure or less). Due to this effect, after the cutoff, the fluid remaining inside the discharge nozzle 56 is sucked into the pump again.
[0083]
As a result, a fluid mass due to surface tension is not formed at the tip of the discharge nozzle, and stringing and dropping are eliminated. In the present invention, the degree of suction of the fluid into the pump can be finely adjusted by setting the gap h, so that an appropriate state without excessive suction can be set.
[0084]
When a powder fluid such as an adhesive containing fine particles is applied, the minimum value δmin of the gap δ may be set to be larger than the fine particle diameter φd.
[0085]
[Equation 3]

[0086]
In order to obtain a larger gap, it is sufficient to increase the outer diameter of the piston and select appropriate values for the groove depth, the groove angle, and the like. Alternatively, a cylindrical flange having a dynamic pressure groove may be provided.
[0087]
In the present embodiment, the pressure feed groove and the seal groove are formed only on the thrust end face of the piston. However, a groove for assisting the pumping action of any of the grooves may be formed on the circumferential surface of the piston shaft or on the opposing surface thereof.
[0088]
As the axial driving means, a linear motor such as a moving magnet, an electromagnetic solenoid, or the like can be used. In the present embodiment, a giant magnetostrictive element is used for the axial driving means. However, in a pump handling a minute flow rate, the stroke of the gap δ for forming a “non-contact seal” may be on the order of several tens of microns, The limit of the stroke of an electrostrictive element such as an element or a piezo element was not a problem.
[0089]
Further, when discharging a high-viscosity fluid, a large discharge pressure is expected to be generated due to the squeezing action. In this case, since the first actuator 1 is required to have a large thrust against high fluid pressure, it is preferable to use an electromagnetic strain type actuator which can easily output a force of several hundred to several thousand N. Since the electromagnetic distortion element has a frequency response of several MHz or more, the main axis can be linearly moved with high response. Therefore, the discharge amount of the high-viscosity fluid can be controlled with high response and high accuracy.
[0090]
Further, when a giant magnetostrictive element is used for the axial driving means, the conductive brush can be omitted as compared with the case where a piezoelectric element is used, so that the load on the motor (rotating means) can be reduced and the overall configuration is extremely simple. Therefore, the moment of inertia of the moving part can be minimized, and the diameter of the dispenser can be reduced.
[0091]
In the present embodiment, both members are relatively moved in the axial direction by the axial driving means while the piston and the housing are relatively rotated. That is, in this case, the piston is driven by a two-degree-of-freedom actuator constituted by a motor and a giant magnetostrictive element.
[0092]
Instead of the two-degree-of-freedom actuator as in the present embodiment, the axial driving means and the rotating means may be configured separately. For example, as in the technique described in Japanese Patent Application Laid-Open No. 2002-143745, the piston is given only rotation by a motor, and the gap between the piston end faces is controlled by an actuator such as a piezoelectric element provided on the fixed side. Good.
[0093]
In the present embodiment, the piston has a single-shaft configuration, but may have a double-piston configuration as in the technique described in JP-A-2002-001192 described above. In this case, the outer peripheral side groove and the inner peripheral side groove may be formed on any end surface (or the opposing surface) of the piston and the sleeve for accommodating the piston. Alternatively, the outer circumferential groove and the inner circumferential groove may be formed as a set only on the sleeve side.
[0094]
【The invention's effect】
The following effects can be obtained by the fluid rotating device using the present invention.
1. High-speed discharge interruption and start can be performed.
2. No troubles such as clogging of the flow path and change in fluid characteristics due to powder compression damage occur.
3. Further, the pump of the present invention can have the following features.
[0095]
(1) High-speed application of high-viscosity fluid is possible.
[0096]
(2) A very small amount can be discharged with high precision.
[0097]
If the present invention is used, for example, for dispensers of surface mount, for applying phosphors for PDPs and CRT displays, and for applying seal materials for liquid crystal panels, the merits of the present invention can be fully exhibited, and the effect is enormous.
[Brief description of the drawings]
FIG. 1 is a model diagram showing the principle of the present invention.
FIG. 2 is a diagram showing an analysis result of a relationship between a pressure generated in two dynamic pressure grooves and a gap.
FIG. 3 is a diagram illustrating a relationship between a generated pressure and a gap when two dynamic pressure grooves are combined.
FIG. 4 is a model diagram showing a flow state of a fluid at a piston end face portion, in which (a) shows a small gap and (b) shows a large gap.
FIG. 5 is a diagram showing a relationship between a gap at a piston end face and time.
FIG. 6 is a diagram showing a relationship between generated pressure and time.
FIG. 7 is a diagram showing a relationship between a gap at a piston end surface and time.
FIG. 8 is a diagram showing a relationship between squeeze pressure and time.
FIG. 9 is a front sectional view of a dispenser according to a specific embodiment of the present invention.
FIG. 10 is a front sectional view of a conventional pneumatic dispenser.
[Explanation of symbols]
51 axes
52 Housing
63 Pump room
55 inlet
56 outlet
54 Means for rotating
53 axial drive means
59 Pumping groove
60 Seal groove

Claims (5)

Means for relatively rotating the shaft and a housing for housing the shaft, axial driving means for varying the gap between the end surface of the shaft and its opposing surface, a pump chamber formed by the shaft and the housing, and an external A fluid discharge device comprising a fluid inlet and a fluid outlet for communicating
A pumping groove formed on the end surface of the shaft and a relative movement surface thereof and a pumping groove for pumping the fluid flowing into the pump chamber to a discharge port side, and a direction opposite to the pumping groove formed on the relative movement surface. When the gap is small, the pressure-feeding groove discharges the fluid, and when the gap is large, the seal-groove is configured such that the fluid is shut off. A fluid ejection device, wherein a seal groove is formed. The fluid ejection device according to claim 1, wherein each of the pressure feeding groove and the seal groove is formed on one of an outer peripheral side and an inner peripheral side of the relative movement surface. The fluid ejection device according to claim 2, wherein the pressure-feeding groove is formed on an outer peripheral side of the relative moving surface, and the seal groove is formed on an inner peripheral side of the relative moving surface. The fluid discharge device according to claim 1, wherein the groove depth of the seal groove is larger than that of the pressure feed groove. When the gap between the relative moving surfaces is large, the pumping action of the fluid by the seal groove acts, and when the gap is small, the relative movement of the seal groove and the pumping groove is performed such that the pumping action of the fluid by the pumping groove acts. When the fluid is released, the gap is narrowed so that the gap is narrowed so that the fluid flows out of the discharge port by the pressure feeding groove, and when the fluid is shut off, the fluid flows in the direction opposite to the discharge port by the seal groove. A fluid discharge method, wherein the discharge is interrupted by giving an action to the fluid.

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