JP4285341B2

JP4285341B2 - Electrodeless discharge lamp lighting device

Info

Publication number: JP4285341B2
Application number: JP2004188789A
Authority: JP
Inventors: 進吾増本; 大志城戸; 紳司牧村; 明中城
Original assignee: Panasonic Corp; Matsushita Electric Works Ltd
Current assignee: Panasonic Corp; Panasonic Electric Works Co Ltd
Priority date: 2004-06-25
Filing date: 2004-06-25
Publication date: 2009-06-24
Anticipated expiration: 2024-06-25
Also published as: JP2006012640A

Description

本発明は、無電極放電灯に近接して配置された誘導コイルに高周波電力を供給することにより無電極放電灯を点灯させる無電極放電灯点灯装置に関するものである。 The present invention relates to an electrodeless discharge lamp lighting device for lighting an electrodeless discharge lamp by supplying high-frequency power to an induction coil disposed in the vicinity of the electrodeless discharge lamp.

従来から、バルブ内に放電ガスが封入されてなる無電極放電灯に近接して配置された誘導コイルに高周波電力を供給し、誘導コイルに高周波電磁界を発生させることにより無電極放電灯を点灯させる無電極放電灯点灯装置が提供されている（例えば、特許文献１参照）。 Conventionally, high-frequency power is supplied to an induction coil placed close to an electrodeless discharge lamp in which a discharge gas is sealed in a bulb, and the induction coil is caused to generate a high-frequency electromagnetic field, thereby lighting the electrodeless discharge lamp. An electrodeless discharge lamp lighting device is provided (see, for example, Patent Document 1).

この種の無電極放電灯点灯装置として、例えば図１１及び図１２に示すように、誘導コイルに供給される高周波電力を生成する電源回路を構成する回路部品が実装されたプリント配線板１と、プリント配線板１を収納するハウジング２とを備えるものがある。電磁ノイズの遮蔽のために、ハウジング２は金属で形成されることが多い。 As this type of electrodeless discharge lamp lighting device, for example, as shown in FIGS. 11 and 12, a printed wiring board 1 on which circuit components constituting a power supply circuit that generates high-frequency power supplied to an induction coil are mounted; Some have a housing 2 that houses a printed wiring board 1. In order to shield electromagnetic noise, the housing 2 is often made of metal.

この種の無電極放電灯装置において、プリント配線板１の印刷面に設けられた導電パターン（図示せず）を湿気から保護するために、従来は、図１１に示すようにハウジング２内においてプリント配線板１を封止樹脂３で封止したり、図１２に示すようにプリント配線板１に封止樹脂３を塗布して導電パターンを覆ったりしていた。
特開２００２−１４０９９６号公報 In this type of electrodeless discharge lamp apparatus, in order to protect a conductive pattern (not shown) provided on the printed surface of the printed wiring board 1 from moisture, conventionally, printing is performed in the housing 2 as shown in FIG. The wiring board 1 is sealed with the sealing resin 3, or the conductive resin is covered by applying the sealing resin 3 to the printed wiring board 1 as shown in FIG.
JP 2002-140996 A

ここで、封止樹脂３は空気に比べて比誘電率が高いため、図１１のようにハウジング２に封止樹脂３を充填してプリント配線板１を封止すると、プリント配線板１の導電パターンとハウジング２の内面との間に発生する浮遊容量が大きくなる。一般に、高周波電力を生成する電源回路は一部が誘導コイルと無電極放電灯とともに共振回路を構成し、この共振回路はＱ値が高いため、電源回路の出力は浮遊容量の影響を受けやすく、浮遊容量が大きいと始動時に無電極放電灯がちらつく、あるいは全く点灯しないなどの問題が発生するおそれがある。したがって、図１１のようにハウジング２に封止樹脂３を充填してプリント配線板１を封止する場合には、浮遊容量を小さくして上記の問題の発生を防止するために、プリント配線板１の印刷面に対向するハウジング２の内面とプリント配線盤１との間の距離を大きくとる必要があり、低背化が難しかった。 Here, since the relative dielectric constant of the sealing resin 3 is higher than that of air, when the printed wiring board 1 is sealed by filling the housing 2 with the sealing resin 3 as shown in FIG. The stray capacitance generated between the pattern and the inner surface of the housing 2 is increased. In general, a part of a power supply circuit that generates high-frequency power constitutes a resonance circuit together with an induction coil and an electrodeless discharge lamp. Since this resonance circuit has a high Q value, the output of the power supply circuit is easily affected by stray capacitance, If the stray capacitance is large, there may be a problem that the electrodeless discharge lamp flickers at start-up or does not light at all. Therefore, when the printed wiring board 1 is sealed by filling the housing 2 with the sealing resin 3 as shown in FIG. 11, the printed wiring board is used in order to reduce the stray capacitance and prevent the above problem from occurring. Therefore, it is necessary to increase the distance between the inner surface of the housing 2 facing the printing surface 1 and the printed wiring board 1, and it is difficult to reduce the height.

一方、図１２のようにプリント配線板１に封止樹脂３を塗布する場合、封止樹脂３とハウジング２の内面との間に空気を介在させることによる浮遊容量の低減及び低背化は可能である。しかし、プリント配線板１に封止樹脂３を塗布する場合、封止時に封止樹脂３がプリント配線板１から流れ落ちることがないように、封止樹脂３としては粘度の高いものを用いる必要があるので、封止樹脂３の流れを利用することができなかったため、製造コストが増大していた。また、封止樹脂３の厚さを均一にすることや、広い範囲を封止することが難しかった。 On the other hand, when the sealing resin 3 is applied to the printed wiring board 1 as shown in FIG. 12, the floating capacitance can be reduced and the height can be reduced by interposing air between the sealing resin 3 and the inner surface of the housing 2. It is. However, when the sealing resin 3 is applied to the printed wiring board 1, it is necessary to use a high-viscosity sealing resin 3 so that the sealing resin 3 does not flow down from the printed wiring board 1 during sealing. Therefore, since the flow of the sealing resin 3 could not be used, the manufacturing cost was increased. Further, it is difficult to make the thickness of the sealing resin 3 uniform and to seal a wide range.

本発明は上記事由に鑑みて為されたものであり、その目的は、低背化が可能であって、かつ製造の容易な無電極放電灯点灯装置を提供することにある。 The present invention has been made in view of the above reasons, and an object of the present invention is to provide an electrodeless discharge lamp lighting device that can be reduced in height and is easy to manufacture.

請求項１の発明は、バルブ内に放電ガスが封入されてなる無電極放電灯に近接して配置された誘導コイルに高周波電力を供給し、誘導コイルに高周波電磁界を発生させることにより無電極放電灯を点灯させる無電極放電灯点灯装置であって、
誘導コイルに供給される高周波電力を生成するための電源回路を構成する回路部品が実装されたプリント配線板と、プリント配線板の印刷面に設けられた導電パターンを印刷面に沿った面内で囲む充填枠と、充填枠に充填され導電パターンを覆う封止樹脂と、プリント配線板並びに充填枠が収納される金属製のハウジングと、ハウジングにおいてプリント配線板の印刷面に対向する内面と封止樹脂との間に隙間が空くようにプリント配線板をハウジング内で支持する支持手段と、充填枠によって囲まれた範囲に対してプリント配線板を挟んだ反対側を囲む部品面充填枠と、部品面充填枠に充填された部品面封止樹脂とを備えることを特徴とする。 According to the first aspect of the present invention, high frequency power is supplied to an induction coil disposed in the vicinity of an electrodeless discharge lamp in which a discharge gas is enclosed in a bulb, and a high frequency electromagnetic field is generated in the induction coil, thereby preventing electrodelessness. An electrodeless discharge lamp lighting device for lighting a discharge lamp,
A printed wiring board on which circuit components constituting a power supply circuit for generating high-frequency power supplied to the induction coil are mounted, and a conductive pattern provided on the printed surface of the printed wiring board within a plane along the printed surface. Surrounding filling frame, sealing resin filled in the filling frame and covering the conductive pattern, a metal housing housing the printed wiring board and the filling frame, and an inner surface facing the printed surface of the printed wiring board in the housing Support means for supporting the printed wiring board in the housing so that there is a gap between the resin, a part surface filling frame that surrounds the opposite side of the printed wiring board with respect to the area surrounded by the filling frame, and parts And a component surface sealing resin filled in the surface filling frame .

この発明によれば、封止時には充填枠によって封止樹脂の漏出が防止されるので、封止樹脂として粘度の低いものを用いることができるから、封止樹脂の塗布によって導電パターンを封止する場合に比べて製造が容易となる。また、プリント配線板の印刷面に対向する内面と封止樹脂との間に隙間を空けているから、ハウジング内に封止樹脂を充填してプリント配線板を封止する場合に比べ、プリント配線板の導電パターンとハウジングとの間の浮遊容量を小さく抑えながらも、プリント配線板とハウジングとの間の距離を小さくして低背化が可能となる。しかも、プリント配線板にスルーホールが設けられている場合にも、スルーホールを通じて印刷面に水が浸入することを防ぐことができる。 According to the present invention, since the sealing resin is prevented from leaking out by the filling frame at the time of sealing, a resin having a low viscosity can be used as the sealing resin. Therefore, the conductive pattern is sealed by applying the sealing resin. Manufacturing is easier than in the case. Also, since there is a gap between the inner surface facing the printed surface of the printed wiring board and the sealing resin, compared to the case where the printed wiring board is sealed by filling the housing with the sealing resin. While the stray capacitance between the conductive pattern of the board and the housing is kept small, the distance between the printed wiring board and the housing can be reduced to reduce the height. In addition, even when a through hole is provided in the printed wiring board, water can be prevented from entering the printing surface through the through hole.

請求項２の発明は、請求項１の発明において、充填枠と部品面充填枠とが互いに連結されていることを特徴とする。 The invention of claim 2 is characterized in that, in the invention of claim 1 , the filling frame and the component surface filling frame are connected to each other.

この発明によれば、充填枠及び部品面充填枠を同時にプリント配線板に取り付けることができるから、製造がさらに容易となる。 According to the present invention, since the filling frame and the component surface filling frame can be attached to the printed wiring board at the same time, the manufacturing is further facilitated.

請求項３の発明は、請求項１又は２の発明において、充填枠は、回路部品のうち比較的に発熱量の多い発熱部品を囲み、
印刷面に沿った面内で充填枠に囲まれるとともに発熱部品を印刷面に沿った面内で囲み充填枠よりもプリント配線板の厚さ方向へ突出する放熱用充填枠と、放熱用充填枠に充填された放熱用封止樹脂とを備え、放熱用封止樹脂をハウジングに接触させたことを特徴とする。 The invention of claim 3 is the invention of claim 1 or 2 , wherein the filling frame surrounds a heat generating component having a relatively large heat generation amount among the circuit components,
A heat-dissipating filling frame that is surrounded by a filling frame in a plane along the printing surface and that surrounds the heat-generating component within the surface along the printing surface and protrudes in the thickness direction of the printed wiring board from the filling frame, and a heat-dissipation filling frame And a heat-dissipating sealing resin filled with the heat-dissipating sealing resin in contact with the housing .

この発明によれば、放熱用封止樹脂を通じた発熱部品の放熱が可能となる。 According to the present invention, it is possible to radiate heat from the heat-generating component through the radiating sealing resin.

請求項４の発明は、バルブ内に放電ガスが封入されてなる無電極放電灯に近接して配置された誘導コイルに高周波電力を供給し、誘導コイルに高周波電磁界を発生させることにより無電極放電灯を点灯させる無電極放電灯点灯装置であって、誘導コイルに供給される高周波電力を生成するための電源回路を構成する回路部品が実装されたプリント配線板と、プリント配線板の印刷面に設けられた導電パターンを印刷面に沿った面内で囲む充填枠と、充填枠に充填され導電パターンを覆う封止樹脂と、プリント配線板並びに充填枠が収納される金属製のハウジングと、ハウジングにおいてプリント配線板の印刷面に対向する内面と封止樹脂との間に隙間が空くようにプリント配線板をハウジング内で支持する支持手段とを備え、充填枠は、回路部品のうち比較的に発熱量の多い発熱部品を囲み、充填する封止樹脂の量を、発熱部品が封止樹脂からプリント配線板の厚さ方向に突出する程度とし、発熱部品の封止樹脂から突出した部位を、熱伝導率の高い材料からなる伝熱体を介してハウジングに熱的に接続したことを特徴とする。 According to a fourth aspect of the present invention , high frequency power is supplied to an induction coil arranged in the vicinity of an electrodeless discharge lamp in which a discharge gas is sealed in a bulb, and a high frequency electromagnetic field is generated in the induction coil, thereby preventing the electrodeless. An electrodeless discharge lamp lighting device for lighting a discharge lamp, wherein a printed wiring board on which circuit components constituting a power supply circuit for generating high-frequency power supplied to an induction coil are mounted, and a printed surface of the printed wiring board A filling frame that encloses the conductive pattern provided in the plane along the printing surface, a sealing resin that fills the filling frame and covers the conductive pattern, a metal housing that houses the printed wiring board and the filling frame, And a supporting means for supporting the printed wiring board in the housing so that a gap is provided between the inner surface of the housing facing the printed surface of the printed wiring board and the sealing resin. Enclose the heat generating component that generates a relatively large amount of heat, and the amount of sealing resin to be filled is such that the heat generating component protrudes from the sealing resin in the thickness direction of the printed wiring board. The part protruded from is thermally connected to the housing through a heat transfer body made of a material having high thermal conductivity .

この発明によれば、封止時には充填枠によって封止樹脂の漏出が防止されるので、封止樹脂として粘度の低いものを用いることができるから、封止樹脂の塗布によって導電パターンを封止する場合に比べて製造が容易となる。また、プリント配線板の印刷面に対向する内面と封止樹脂との間に隙間を空けているから、ハウジング内に封止樹脂を充填してプリント配線板を封止する場合に比べ、プリント配線板の導電パターンとハウジングとの間の浮遊容量を小さく抑えながらも、プリント配線板とハウジングとの間の距離を小さくして低背化が可能となり、さらに、伝熱体を通じた発熱部品の放熱が可能となる。 According to the present invention, since the sealing resin is prevented from leaking out by the filling frame at the time of sealing, a resin having a low viscosity can be used as the sealing resin. Therefore, the conductive pattern is sealed by applying the sealing resin. Manufacturing is easier than in the case. Also, since there is a gap between the inner surface facing the printed surface of the printed wiring board and the sealing resin, compared to the case where the printed wiring board is sealed by filling the housing with the sealing resin. While minimizing the stray capacitance between the conductive pattern of the board and the housing, the distance between the printed wiring board and the housing can be reduced, and the height can be reduced. Is possible.

請求項５の発明は、バルブ内に放電ガスが封入されてなる無電極放電灯に近接して配置された誘導コイルに高周波電力を供給し、誘導コイルに高周波電磁界を発生させることにより無電極放電灯を点灯させる無電極放電灯点灯装置であって、誘導コイルに供給される高周波電力を生成するための電源回路を構成する回路部品が実装されたプリント配線板と、プリント配線板の印刷面に設けられた導電パターンを印刷面に沿った面内で囲む充填枠と、充填枠に充填され導電パターンを覆う封止樹脂と、プリント配線板並びに充填枠が収納される金属製のハウジングと、ハウジングにおいてプリント配線板の印刷面に対向する内面と封止樹脂との間に隙間が空くようにプリント配線板をハウジング内で支持する支持手段とを備え、プリント配線板に接続される電線を、封止樹脂を通して引き出したことを特徴とする。 According to a fifth aspect of the present invention , high frequency power is supplied to an induction coil disposed in the vicinity of an electrodeless discharge lamp in which a discharge gas is enclosed in a bulb, and a high frequency electromagnetic field is generated in the induction coil, thereby preventing an electrode. An electrodeless discharge lamp lighting device for lighting a discharge lamp, wherein a printed wiring board on which circuit components constituting a power supply circuit for generating high-frequency power supplied to an induction coil are mounted, and a printed surface of the printed wiring board A filling frame that encloses the conductive pattern provided in the plane along the printing surface, a sealing resin that fills the filling frame and covers the conductive pattern, a metal housing that houses the printed wiring board and the filling frame, and a support means for supporting the printed circuit board so gap is formed between the opposing inner surfaces and the sealing resin on the printing surface of the printed wiring board in the housing in the housing, the printed circuit board The wire to be connected, characterized in that drawn through the sealing resin.

この発明によれば、封止時には充填枠によって封止樹脂の漏出が防止されるので、封止樹脂として粘度の低いものを用いることができるから、封止樹脂の塗布によって導電パターンを封止する場合に比べて製造が容易となる。また、プリント配線板の印刷面に対向する内面と封止樹脂との間に隙間を空けているから、ハウジング内に封止樹脂を充填してプリント配線板を封止する場合に比べ、プリント配線板の導電パターンとハウジングとの間の浮遊容量を小さく抑えながらも、プリント配線板とハウジングとの間の距離を小さくして低背化が可能となり、しかも、電線を伝ってハウジング内に水が浸入した場合にも、浸入した水は封止樹脂によって阻止されるから、プリント配線板への水の付着が防止される。 According to the present invention, since the sealing resin is prevented from leaking out by the filling frame at the time of sealing, a resin having a low viscosity can be used as the sealing resin. Therefore, the conductive pattern is sealed by applying the sealing resin. Manufacturing is easier than in the case. Also, since there is a gap between the inner surface facing the printed surface of the printed wiring board and the sealing resin, compared to the case where the printed wiring board is sealed by filling the housing with the sealing resin. While the stray capacitance between the conductive pattern of the board and the housing is kept small, the distance between the printed wiring board and the housing can be reduced, and the height can be reduced. Even in the case of intrusion, the infiltrated water is blocked by the sealing resin, so that the water adheres to the printed wiring board.

請求項６の発明は、バルブ内に放電ガスが封入されてなる無電極放電灯に近接して配置された誘導コイルに高周波電力を供給し、誘導コイルに高周波電磁界を発生させることにより無電極放電灯を点灯させる無電極放電灯点灯装置であって、誘導コイルに供給される高周波電力を生成するための電源回路を構成する回路部品が実装されたプリント配線板と、プリント配線板の印刷面に設けられた導電パターンを印刷面に沿った面内で囲む充填枠と、充填枠に充填され導電パターンを覆う封止樹脂と、プリント配線板並びに充填枠が収納される金属製のハウジングと、ハウジングにおいてプリント配線板の印刷面に対向する内面と封止樹脂との間に隙間が空くようにプリント配線板をハウジング内で支持する支持手段とを備え、充填枠が柔軟性を有する材料からなることを特徴とする。 According to the sixth aspect of the present invention , high frequency power is supplied to an induction coil disposed in the vicinity of an electrodeless discharge lamp in which a discharge gas is enclosed in a bulb, and a high frequency electromagnetic field is generated in the induction coil, thereby preventing the electrodeless. An electrodeless discharge lamp lighting device for lighting a discharge lamp, wherein a printed wiring board on which circuit components constituting a power supply circuit for generating high-frequency power supplied to an induction coil are mounted, and a printed surface of the printed wiring board A filling frame that encloses the conductive pattern provided in the plane along the printing surface, a sealing resin that fills the filling frame and covers the conductive pattern, a metal housing that houses the printed wiring board and the filling frame, and a support means for supporting the printed circuit board so gap is formed between the inner surface and the sealing resin which is opposed to the printing surface of the printed wiring board in the housing in the housing, the filling frame is flexible Characterized in that it consists of a material having.

この発明によれば、封止時には充填枠によって封止樹脂の漏出が防止されるので、封止樹脂として粘度の低いものを用いることができるから、封止樹脂の塗布によって導電パターンを封止する場合に比べて製造が容易となる。また、プリント配線板の印刷面に対向する内面と封止樹脂との間に隙間を空けているから、ハウジング内に封止樹脂を充填してプリント配線板を封止する場合に比べ、プリント配線板の導電パターンとハウジングとの間の浮遊容量を小さく抑えながらも、プリント配線板とハウジングとの間の距離を小さくして低背化が可能となり、しかも、充填枠に封止樹脂を充填する際にプリント配線板に反りが発生した場合でも充填枠が追従するから、プリント配線板と充填枠との間に隙間が生じにくいので、より確実に封止樹脂の漏出を防ぐことができる。 According to the present invention, since the sealing resin is prevented from leaking out by the filling frame at the time of sealing, a resin having a low viscosity can be used as the sealing resin. Therefore, the conductive pattern is sealed by applying the sealing resin. Manufacturing is easier than in the case. Also, since there is a gap between the inner surface facing the printed surface of the printed wiring board and the sealing resin, compared to the case where the printed wiring board is sealed by filling the housing with the sealing resin. while suppressing small stray capacitance between the conductive pattern and the housing of the plate, to reduce the distance between the printed circuit board and the housing enables height reduction, moreover, to fill the sealing resin filling frame Even when the printed wiring board is warped, the filling frame follows. Therefore, a gap is hardly formed between the printed wiring board and the filling frame, so that leakage of the sealing resin can be prevented more reliably.

請求項７の発明は、請求項１乃至請求項６のいずれかの発明において、封止樹脂として、粘度が３０００ｍＰａ・ｓ以下のものを用いたことを特徴とする。 The invention of claim 7 is characterized in that, in any of the inventions of claims 1 to 6 , a sealing resin having a viscosity of 3000 mPa · s or less is used.

本発明によれば、封止時の封止樹脂の漏出が充填枠により防止されるから、粘度が低い封止樹脂を用いて、封止樹脂の充填に要する時間を短縮することができるのである。 According to the present invention, since the leakage of the sealing resin at the time of sealing is prevented by the filling frame, the time required for filling the sealing resin can be shortened by using the sealing resin having a low viscosity. .

本発明によれば、導電パターンを囲む充填枠によって封止の際の封止樹脂の流出が防止されることにより、封止樹脂として粘度の低いものを用いることができるから、封止樹脂の塗布によって導電パターンを封止する場合に比べて製造が容易となる。また、プリント配線板の印刷面に対向する内面と封止樹脂との間に隙間を空けてプリント配線板を支持する支持手段を備えることにより、ハウジング内に封止樹脂を充填してプリント配線板を封止する場合に比べ、プリント配線板の導電パターンとハウジングとの間の浮遊容量を小さく抑えながらも、プリント配線板とハウジングとの間の距離を小さくして低背化が可能となる。 According to the present invention, since the sealing resin is prevented from flowing out at the time of sealing by the filling frame surrounding the conductive pattern, a sealing resin having a low viscosity can be used. Therefore, the manufacturing becomes easier as compared with the case where the conductive pattern is sealed. The printed wiring board is filled with the sealing resin by providing a supporting means for supporting the printed wiring board with a gap between the inner surface facing the printing surface of the printed wiring board and the sealing resin. Compared to the case of sealing, the stray capacitance between the conductive pattern of the printed wiring board and the housing can be kept small, and the distance between the printed wiring board and the housing can be reduced to reduce the height.

以下、本発明を実施するための最良の形態について、図面を参照しながら説明する。 The best mode for carrying out the present invention will be described below with reference to the drawings.

（実施形態１）
本実施形態は、図１に示すように、電源回路を構成する回路部品３が実装された長方形状のプリント配線板１と、プリント配線板１を収納した金属製のハウジング２とを備える。ハウジング２は、プリント配線板１を収納した収納凹部２１ａが一面に設けられた直方体形状のボディ２１と、収納凹部２１ａを覆うカバー２２（図９参照）とからなる。 (Embodiment 1)
As shown in FIG. 1, the present embodiment includes a rectangular printed wiring board 1 on which circuit components 3 constituting a power supply circuit are mounted, and a metal housing 2 that houses the printed wiring board 1. The housing 2 includes a rectangular parallelepiped body 21 in which a storage recess 21a storing the printed wiring board 1 is provided on one surface, and a cover 22 (see FIG. 9) covering the storage recess 21a.

本実施形態における回路部品１１はプリント配線板１の印刷面に表面実装されている。また、プリント配線板１には、印刷面に沿った面内において回路部品１１と導電パターン（図示せず）とを囲む充填枠４が例えば樹脂接着剤で貼着されている。充填枠４には、例えばウレタンを配合した合成樹脂やシリコーン樹脂のような封止樹脂３が充填され、この封止樹脂３により回路部品３と導電パターンとが封止され湿気から保護されている。 The circuit component 11 in the present embodiment is surface-mounted on the printed surface of the printed wiring board 1. Moreover, the filling frame 4 surrounding the circuit component 11 and the conductive pattern (not shown) is attached to the printed wiring board 1 with a resin adhesive, for example, in a plane along the printing surface. The filling frame 4 is filled with a sealing resin 3 such as a synthetic resin or a silicone resin blended with urethane, for example, and the circuit component 3 and the conductive pattern are sealed and protected from moisture by the sealing resin 3. .

ここで、充填枠４としては、例えばゴム系スポンジのような柔軟性を有する材料を用いることが望ましい。この構成を採用すれば、充填枠４に封止樹脂３を充填する際にプリント配線板１に反りが発生しても充填枠４が追従することによりプリント配線板１と充填枠４との間に隙間が生じにくいから、充填枠４からの封止樹脂３の漏出が防止される。 Here, as the filling frame 4, it is desirable to use a flexible material such as rubber sponge. If this configuration is adopted, even when the printed wiring board 1 is warped when the filling resin 4 is filled with the sealing resin 3, the filling frame 4 follows to cause the space between the printed wiring board 1 and the filling frame 4. Therefore, the sealing resin 3 is prevented from leaking from the filling frame 4.

また、封止樹脂３は、１液型でも２液混合型でもよいが、粘度（２液混合型の場合は混合直後の粘度）が３０００ｍＰａ・ｓ以下のものを用いることが、充填に要する時間を短縮するためには望ましい。 In addition, the sealing resin 3 may be a one-pack type or a two-pack type, but if the viscosity (viscosity immediately after mixing in the case of the two-pack type) is 3000 mPa · s or less, the time required for filling is used. It is desirable to shorten

充填枠４は、図１（ｂ）に示すように外周がプリント配線板１の印刷面よりも僅かに小さい角筒形状の４隅を内側へ曲げた形状としてあり、充填枠４及び封止樹脂３からプリント配線板１の４隅が露出するようになっている。そして、プリント配線板１の露出した４隅には、それぞれハウジング２へのねじ止めのためのねじＳ（図２（ｂ）参照）が挿通されるねじ挿通穴１ａが表裏に貫設されている。図２に示すように、収納凹部２１ａの底面の４隅には、それぞれ収納凹部２１ａの開口面へ向かって突出する台座突起２１ｂが例えば曲げ加工によって設けられていて、各台座突起２１ｂの頂点にはそれぞれねじ穴２１ｃが表裏に貫設されている。プリント配線板１は、印刷面を収納凹部２１ａの底面に向けて、露出した４隅がそれぞれ台座突起２１ｂにねじ止めされることによってハウジング２内に支持されている。また、台座突起２１ｂの突出寸法は、収納凹部２１ａの底面と封止樹脂３との間に隙間が空く程度に大きくしてある。つまり、台座突起２１ｂが支持手段である。 As shown in FIG. 1B, the filling frame 4 has a shape in which four corners of a rectangular tube shape whose outer periphery is slightly smaller than the printed surface of the printed wiring board 1 are bent inward, and the filling frame 4 and the sealing resin 3, the four corners of the printed wiring board 1 are exposed. In the exposed four corners of the printed wiring board 1, screw insertion holes 1 a through which screws S (see FIG. 2B) for screwing to the housing 2 are inserted are formed on the front and back sides. . As shown in FIG. 2, at the four corners of the bottom surface of the storage recess 21a, pedestal projections 21b projecting toward the opening surface of the storage recess 21a are provided by bending, for example, at the top of each pedestal projection 21b. Each has a screw hole 21c formed through the front and back. The printed wiring board 1 is supported in the housing 2 by screwing the exposed four corners to the base protrusion 21b with the printing surface facing the bottom surface of the housing recess 21a. Further, the projecting dimension of the base protrusion 21b is large enough to leave a gap between the bottom surface of the storage recess 21a and the sealing resin 3. That is, the base protrusion 21b is a support means.

ここで、プリント配線板１に接続される電線Ｃは、図３に示すように封止樹脂３を通して引き出すことが望ましい。この構成を採用すれば、ハウジング２外から電線Ｃを伝って水が浸入しても、水は封止樹脂３によって阻止されるから、プリント配線板１への水の付着が防止される。 Here, the electric wire C connected to the printed wiring board 1 is desirably drawn out through the sealing resin 3 as shown in FIG. If this configuration is adopted, even if water enters the electric wire C from the outside of the housing 2, the water is blocked by the sealing resin 3, so that the water is prevented from adhering to the printed wiring board 1.

さらに、プリント配線板１とハウジング２との間の絶縁のために、収納凹部２１ａの内面には絶縁シート５を配設することが望ましい。 Furthermore, for the insulation between the printed wiring board 1 and the housing 2, it is desirable to dispose the insulating sheet 5 on the inner surface of the housing recess 21a.

上記構成によれば、封止時には充填枠４によって封止樹脂３の漏出が防止されるので、封止樹脂３として粘度の低いものを用いることができるから、封止樹脂３の塗布によって導電パターンを封止する場合に比べて製造が容易となる。また、台座突起２１ｂによってプリント配線板１を支持することで、プリント配線板１の印刷面に対向する内面と封止樹脂３との間に隙間を空けているから、空気の比誘電率が封止樹脂３よりも小さいことにより、ハウジング２内に封止樹脂３を充填してプリント配線板１を封止する場合に比べ、プリント配線板１の導電パターンとハウジング２との間の浮遊容量を小さく抑えながらも、プリント配線板１とハウジング２との間の距離を小さくして低背化が可能となる。 According to the above configuration, since the sealing resin 3 is prevented from leaking out by the filling frame 4 at the time of sealing, a low-viscosity resin can be used as the sealing resin 3. Manufacture is facilitated compared to the case of sealing. In addition, since the printed wiring board 1 is supported by the base protrusion 21b, a gap is formed between the inner surface facing the printed surface of the printed wiring board 1 and the sealing resin 3, so that the relative dielectric constant of the air is sealed. By being smaller than the stop resin 3, the floating capacitance between the conductive pattern of the printed wiring board 1 and the housing 2 can be reduced compared to the case where the housing 2 is filled with the sealing resin 3 and the printed wiring board 1 is sealed. While keeping it small, the distance between the printed wiring board 1 and the housing 2 can be reduced to reduce the height.

なお、支持手段としては、ハウジング２に台座突起２１ｂやねじ穴２１ｃを設ける代わりに、ハウジング２に取り付けられてプリント配線板１を支持するスペーサ（図示せず）を用いてもよい。また、絶縁シート５に十分な機械的強度があれば、台座突起２１ｂやねじ穴２１ｃをハウジング２に設ける代わりに絶縁シート５に設けてもよい。 As the support means, instead of providing the base 2 with the base protrusion 21b and the screw hole 21c, a spacer (not shown) attached to the housing 2 and supporting the printed wiring board 1 may be used. Further, if the insulating sheet 5 has sufficient mechanical strength, the base protrusion 21 b and the screw hole 21 c may be provided in the insulating sheet 5 instead of being provided in the housing 2.

（実施形態２）
実施形態１において、プリント配線板１にピン挿入実装されている回路部品が存在する場合、ピン挿入実装のために設けられたスルーホールを通じて水がプリント配線板１の印刷面側に浸入することが考えられる。 (Embodiment 2)
In the first embodiment, when there is a circuit component that is pin-mounted on the printed wiring board 1, water may enter the printed surface side of the printed wiring board 1 through a through hole provided for pin insertion mounting. Conceivable.

本実施形態は、上記事由に鑑みて実施形態１を改良したものであり、図４に示すように、充填枠４によって囲まれた範囲に対してプリント配線板１を挟んだ反対側を囲む部品面充填枠４１を設けるとともに、部品面充填枠４１に部品面封止樹脂３１を充填したことを特徴とする。部品面充填枠４１及び部品面封止樹脂３１には、それぞれ充填枠４及び封止樹脂３と同様の材料を用いることができる。 In the present embodiment, the first embodiment is improved in view of the above-described reason, and as shown in FIG. 4, a part surrounding the opposite side of the printed wiring board 1 with respect to the range surrounded by the filling frame 4. A surface filling frame 41 is provided, and the component surface filling frame 41 is filled with a component surface sealing resin 31. The same material as the filling frame 4 and the sealing resin 3 can be used for the component surface filling frame 41 and the component surface sealing resin 31, respectively.

上記構成によれば、プリント配線板１の印刷面側へのスルーホールを通じた水の浸入を部品面封止樹脂３１によって防ぐことができる。また、プリント配線板１の部品面にピン挿入実装されている回路部品を部品面封止樹脂３１によって覆って湿気から保護することができる。 According to the above configuration, the component surface sealing resin 31 can prevent water from entering through the through hole to the printed surface side of the printed wiring board 1. Further, the circuit component that is pin-mounted on the component surface of the printed wiring board 1 can be covered with the component surface sealing resin 31 to be protected from moisture.

また、図５（ａ）（ｂ）に示すように、部品面充填枠４１を充填枠４と一体に形成してもよい。具体的には例えば、充填枠４をプリント配線板１の全周を囲む筒状に形成するとともに、プリント配線板１の４隅を挿通する穴を充填枠４に設けることにより、充填枠４を、図４の例での充填枠４と部品面充填枠４１とがプリント配線板１の辺に沿った４箇所でそれぞれ連結された形状としている。また、充填枠４の内周面には、プリント配線板１の端部が嵌合する溝４ａを設けている。この構成を採用すれば、部品面充填枠４１を別途に取り付ける必要がないから、図４の例に比べて製造が容易となる。 Further, as shown in FIGS. 5A and 5B, the component surface filling frame 41 may be formed integrally with the filling frame 4. Specifically, for example, the filling frame 4 is formed in a cylindrical shape surrounding the entire circumference of the printed wiring board 1 and the filling frame 4 is provided with holes through the four corners of the printed wiring board 1. The filling frame 4 and the component surface filling frame 41 in the example of FIG. 4 are connected to each other at four locations along the side of the printed wiring board 1. Further, a groove 4 a into which an end portion of the printed wiring board 1 is fitted is provided on the inner peripheral surface of the filling frame 4. If this configuration is adopted, it is not necessary to attach the component surface filling frame 41 separately, and therefore, manufacture becomes easier as compared with the example of FIG.

（実施形態３）
ところで、高周波電力を生成する電源回路として一般的に用いられているものはスイッチング素子を有し、スイッチング素子を高周波でオンオフすることによって高周波電力を生成している。したがって、スイッチング素子は比較的に発熱量が多くなる。そして、実施形態１においては、封止樹脂３とハウジング２との間に隙間を空けているので、図１１の従来例のようにハウジング２内に封止樹脂３を充填する場合に比べて放熱の効率が低下して上記スイッチング素子などの比較的に発熱量の多い発熱部品の放熱が不十分となる可能性がある。 (Embodiment 3)
By the way, what is generally used as a power supply circuit for generating high-frequency power has a switching element, and generates high-frequency power by turning on and off the switching element at high frequency. Therefore, the switching element generates a relatively large amount of heat. And in Embodiment 1, since the clearance gap is opened between the sealing resin 3 and the housing 2, compared with the case where the sealing resin 3 is filled in the housing 2 as in the conventional example of FIG. Efficiency may be reduced, and heat dissipation of a heat generating component having a relatively large heat generation amount such as the switching element may be insufficient.

本実施形態は上記事由に鑑みて実施形態１を改良したものであり、図６に示すように、発熱部品１２の印刷面からの突出寸法よりも封止樹脂３の厚さ寸法を小さくし、発熱部品１２を封止樹脂３から露出させている。さらに、熱伝導率の高い材料からなる伝熱体６を、絶縁シート５に設けた穴に挿通して、発熱部品１２において封止樹脂３から露出した部位と、収納凹部２１ａの底面とにそれぞれ接触させることにより、発熱部品１２を伝熱体６を介してハウジング２に熱的に接続している。 This embodiment is an improvement of the first embodiment in view of the above reasons, and as shown in FIG. 6, the thickness dimension of the sealing resin 3 is made smaller than the projecting dimension from the printing surface of the heat generating component 12, The heat generating component 12 is exposed from the sealing resin 3. Furthermore, the heat transfer body 6 made of a material having a high thermal conductivity is inserted into the hole provided in the insulating sheet 5, and is exposed to the portion exposed from the sealing resin 3 in the heat generating component 12 and the bottom surface of the storage recess 21a. By making contact, the heat generating component 12 is thermally connected to the housing 2 via the heat transfer body 6.

上記構成によれば、伝熱体６を通じた発熱部品１２の放熱が可能となる。 According to the above configuration, the heat generating component 12 can be dissipated through the heat transfer body 6.

また、伝熱体６を設ける代わりに、図７に示すように、発熱部品１２において封止樹脂３から露出した部位を印刷面に沿った面内において囲む放熱用充填枠４２を封止樹脂３に貼着し、放熱用充填枠４２には熱伝導率の高い合成樹脂からなる放熱用樹脂３２を充填して発熱部品１２を封止してもよい。この構成を採用すれば、放熱用樹脂３２を通じた発熱部品１２の放熱が可能である。また、伝熱体６のように発熱部品１２に対する位置がずれて放熱の効率が低下するようなことがない。 Further, instead of providing the heat transfer body 6, as shown in FIG. 7, the heat-dissipating filling frame 42 that surrounds the portion exposed from the sealing resin 3 in the heat-generating component 12 within the plane along the printing surface is provided. The heat-generating component 12 may be sealed by filling the heat-dissipating filling frame 42 with a heat-dissipating resin 32 made of a synthetic resin having a high thermal conductivity. If this configuration is adopted, the heat generating component 12 can be dissipated through the heat dissipating resin 32. In addition, unlike the heat transfer body 6, the position with respect to the heat generating component 12 is not shifted and the efficiency of heat dissipation is not reduced.

さらに、図８に示すように、放熱用充填枠４２を、充填枠４に囲まれかつ印刷面からの突出寸法が充填枠４よりも大きい形状とし、放熱用充填枠４２を充填枠４と同時にプリント配線板１に取り付けるようにしてもよい。この構成を採用すれば、放熱用充填枠４２の取り付けと充填枠４の取り付け、放熱用封止樹脂３２の充填と封止樹脂３の充填とをそれぞれ同時に行うことができるから、図７の例に比べて製造が容易となる。 Further, as shown in FIG. 8, the heat dissipating filling frame 42 is formed in a shape surrounded by the filling frame 4 and having a protruding dimension from the printing surface larger than that of the filling frame 4. You may make it attach to the printed wiring board 1. FIG. If this configuration is adopted, the heat radiation filling frame 42 and the filling frame 4 can be attached, and the heat radiation sealing resin 32 and the sealing resin 3 can be simultaneously filled. Compared to the above, manufacturing becomes easier.

なお、本実施形態においては、伝熱体６や放熱用封止樹脂３２が支持手段ともなり得るから、台座突起２１ｂの数を減らすことができる。 In the present embodiment, since the heat transfer body 6 and the heat radiation sealing resin 32 can also serve as support means, the number of base protrusions 21b can be reduced.

（実施形態４）
本実施形態の基本構成は実施形態１と共通であるので、共通する構成については同じ符号を付して図示並びに説明を省略する。 (Embodiment 4)
Since the basic configuration of the present embodiment is the same as that of the first embodiment, the same components are denoted by the same reference numerals, and illustration and description thereof are omitted.

実施形態１ではプリント配線板１の印刷面を収納凹部２１ａの底面に向けていたのに対し、本実施形態は図９に示すようにプリント配線板１の印刷面を収納凹部２１ａの開口に向けていることを特徴とする。また、支持手段としては、台座突起２１ｂを設ける代わりに、収納凹部２１ａの内側面から内側へ突設された棚状突起２１ｄに、プリント配線板１を載置している。 In the first embodiment, the printed surface of the printed wiring board 1 is directed toward the bottom surface of the storage recess 21a. In the present embodiment, the printed surface of the printed wiring board 1 is directed toward the opening of the storage recess 21a as shown in FIG. It is characterized by. Moreover, as a support means, instead of providing the base protrusion 21b, the printed wiring board 1 is placed on a shelf-like protrusion 21d that protrudes inward from the inner surface of the storage recess 21a.

上記構成によれば、プリント配線板１を収納凹部２１ａに収納した後に封止樹脂３を充填することができるから、製造の自由度が向上している。ここで、プリント配線板１の部品面に回路部品１１が実装されている場合、印刷面を上向きとしてプリント配線板１を平面上に安定した姿勢で載置することができないから、充填枠４に封止樹脂３を充填する際は何らかの手段でプリント配線板１を支持する必要がある。しかし、プリント配線板１をボディ２に取り付けた後に封止樹脂３を充填すれば、プリント配線板１はボディ２に支持されるから、充填枠４に封止樹脂３を充填する際にプリント配線板１を支持する手段を別途に用意する必要がない。 According to the said structure, since the sealing resin 3 can be filled after accommodating the printed wiring board 1 in the accommodation recessed part 21a, the freedom degree of manufacture is improving. Here, when the circuit component 11 is mounted on the component surface of the printed wiring board 1, the printed wiring board 1 cannot be placed in a stable posture on the plane with the printing surface facing upward. When filling the sealing resin 3, it is necessary to support the printed wiring board 1 by some means. However, if the sealing resin 3 is filled after the printed wiring board 1 is attached to the body 2, the printed wiring board 1 is supported by the body 2, so that when the filling frame 4 is filled with the sealing resin 3, the printed wiring There is no need to prepare a separate means for supporting the plate 1.

さらに、図１０に示すように、充填枠４を一端部が内側へ折り返された筒形状とし、プリント配線板１を充填枠４に収納して充填枠４の折り返された一端をプリント配線板１の部品面の周縁部に貼着することにより、封止樹脂３がプリント配線板１の印刷面と部品面の周縁部とに跨るようにしてもよい。この構成を採用すれば、プリント配線板１と充填枠４との結合部がプリント配線板１の印刷面から離れることになるから、プリント配線板１と充填枠４との間からプリント配線板１の印刷面への水の浸入をより確実に防ぐことができる。 Further, as shown in FIG. 10, the filling frame 4 has a cylindrical shape with one end folded back inward, the printed wiring board 1 is housed in the filling frame 4, and the folded end of the filling frame 4 is connected to the printed wiring board 1. By adhering to the peripheral part of the component surface, the sealing resin 3 may straddle the printed surface of the printed wiring board 1 and the peripheral part of the component surface. If this configuration is adopted, the connecting portion between the printed wiring board 1 and the filling frame 4 is separated from the printing surface of the printed wiring board 1, so that the printed wiring board 1 is interposed between the printed wiring board 1 and the filling frame 4. It is possible to more reliably prevent water from entering the printing surface.

本発明の実施形態１を示す図であり、（ａ）は断面図、（ｂ）はプリント配線板の下面図である。It is a figure which shows Embodiment 1 of this invention, (a) is sectional drawing, (b) is a bottom view of a printed wiring board. 同上を示す図であり、（ａ）はボディの平面図、（ｂ）はボディへのプリント配線板の取り付け方を示す説明図である。It is a figure which shows the same as the above, (a) is a top view of a body, (b) is explanatory drawing which shows how to attach the printed wiring board to a body. 同上に電線を接続した状態を示す断面図である。It is sectional drawing which shows the state which connected the electric wire to the same. 本発明の実施形態２を示す断面図である。It is sectional drawing which shows Embodiment 2 of this invention. 同上の別の形態を示す図であり、（ａ）は断面図、（ｂ）はプリント配線板の下面図である。It is a figure which shows another form same as the above, (a) is sectional drawing, (b) is a bottom view of a printed wiring board. 本発明の実施形態３を示す断面図である。It is sectional drawing which shows Embodiment 3 of this invention. 同上の別の形態を示す断面図である。It is sectional drawing which shows another form same as the above. 同上の更に別の形態を示す断面図である。It is sectional drawing which shows another form same as the above. 本発明の実施形態４を示す断面図である。It is sectional drawing which shows Embodiment 4 of this invention. 同上の別の形態を示す断面図である。It is sectional drawing which shows another form same as the above. 従来例を示す断面図である。It is sectional drawing which shows a prior art example. 別の従来例を示す断面図である。It is sectional drawing which shows another prior art example.

Explanation of symbols

１プリント配線板
２ハウジング
３封止樹脂
４充填枠
６伝熱体
１１回路部品
１２発熱部品
２１ボディ
２１ａ収納凹部
２１ｂ台座突起
２１ｄ棚状突起
２２カバー
３１部品面封止樹脂
３２放熱用封止樹脂
４１部品面充填枠
４２放熱用充填枠
Ｃ電線 DESCRIPTION OF SYMBOLS 1 Printed wiring board 2 Housing 3 Sealing resin 4 Filling frame 6 Heat-transfer body 11 Circuit component 12 Heating component 21 Body 21a Housing recessed part 21b Base protrusion 21d Shelf-shaped protrusion 22 Cover 31 Parts surface sealing resin 32 Heat radiation sealing resin 41 Parts side filling frame 42 Heat radiation filling frame C Electric wire

Claims

An electrodeless lamp that turns on the electrodeless discharge lamp by supplying high-frequency power to an induction coil arranged in the vicinity of an electrodeless discharge lamp in which a discharge gas is enclosed in a bulb and generating a high-frequency electromagnetic field in the induction coil. A discharge lamp lighting device,
A printed wiring board on which circuit components constituting a power supply circuit for generating high-frequency power supplied to the induction coil are mounted, and a conductive pattern provided on the printed surface of the printed wiring board within a plane along the printed surface. Surrounding filling frame, sealing resin filled in the filling frame and covering the conductive pattern, a metal housing housing the printed wiring board and the filling frame, and an inner surface facing the printed surface of the printed wiring board in the housing Support means for supporting the printed wiring board in the housing so that there is a gap between the resin, a part surface filling frame that surrounds the opposite side of the printed wiring board with respect to the area surrounded by the filling frame, and parts An electrodeless discharge lamp lighting device comprising: a component surface sealing resin filled in a surface filling frame .

2. The electrodeless discharge lamp lighting device according to claim 1, wherein the filling frame and the component surface filling frame are connected to each other .

The filling frame encloses heat generating parts with relatively large heat generation among circuit parts,
A heat-dissipating filling frame that is surrounded by a filling frame in a plane along the printing surface and that surrounds the heat-generating component within the surface along the printing surface and protrudes in the thickness direction of the printed wiring board from the filling frame, and a heat-dissipation filling frame an electrodeless discharge lamp lighting device according to claim 1 or 2, wherein the a filled radiating sealing resin, and the heat radiating sealing resin in contact with the housing.

An electrodeless lamp that turns on the electrodeless discharge lamp by supplying high-frequency power to an induction coil arranged in the vicinity of an electrodeless discharge lamp in which a discharge gas is enclosed in a bulb and generating a high-frequency electromagnetic field in the induction coil. A discharge lamp lighting device,
A printed wiring board on which circuit components constituting a power supply circuit for generating high-frequency power supplied to the induction coil are mounted, and a conductive pattern provided on the printed surface of the printed wiring board within a plane along the printed surface. Surrounding filling frame, sealing resin filled in the filling frame and covering the conductive pattern, a metal housing housing the printed wiring board and the filling frame, and an inner surface facing the printed surface of the printed wiring board in the housing A support means for supporting the printed wiring board in the housing so that a gap is left between the resin and the resin;
The filling frame encloses heat generating parts with relatively large heat generation among circuit parts,
The amount of sealing resin to be filled is such that the heat-generating component protrudes from the sealing resin in the thickness direction of the printed wiring board, and the portion protruding from the sealing resin of the heat-generating component is transferred from a material having high thermal conductivity. an electrodeless discharge lamp lighting device you characterized by being thermally connected to the housing via a heat member.

An electrodeless lamp that turns on the electrodeless discharge lamp by supplying high-frequency power to an induction coil arranged in the vicinity of an electrodeless discharge lamp in which a discharge gas is enclosed in a bulb and generating a high-frequency electromagnetic field in the induction coil. A discharge lamp lighting device,
A printed wiring board on which circuit components constituting a power supply circuit for generating high-frequency power supplied to the induction coil are mounted, and a conductive pattern provided on the printed surface of the printed wiring board within a plane along the printed surface. Surrounding filling frame, sealing resin filled in the filling frame and covering the conductive pattern, a metal housing housing the printed wiring board and the filling frame, and an inner surface facing the printed surface of the printed wiring board in the housing A support means for supporting the printed wiring board in the housing so that a gap is left between the resin and the resin;
The wires are connected to the printed wiring board, an electrodeless discharge lamp lighting device you characterized in that drawn through the sealing resin.

An electrodeless lamp that turns on the electrodeless discharge lamp by supplying high-frequency power to an induction coil arranged in the vicinity of an electrodeless discharge lamp in which a discharge gas is enclosed in a bulb and generating a high-frequency electromagnetic field in the induction coil. A discharge lamp lighting device,
A printed wiring board on which circuit components constituting a power supply circuit for generating high-frequency power supplied to the induction coil are mounted, and a conductive pattern provided on the printed surface of the printed wiring board within a plane along the printed surface. Surrounding filling frame, sealing resin filled in the filling frame and covering the conductive pattern, a metal housing housing the printed wiring board and the filling frame, and an inner surface facing the printed surface of the printed wiring board in the housing A support means for supporting the printed wiring board in the housing so that a gap is left between the resin and the resin;
An electrodeless discharge lamp lighting device you characterized in that the filling frame is made of a material having flexibility.

The electrodeless discharge lamp lighting device according to any one of claims 1 to 6, wherein a sealing resin having a viscosity of 3000 mPa · s or less is used .