JP4033058B2

JP4033058B2 - Acceleration sensor

Info

Publication number: JP4033058B2
Application number: JP2003188784A
Authority: JP
Inventors: 康明渡部; 直博谷口; 淳司松崎
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 2003-06-30
Filing date: 2003-06-30
Publication date: 2008-01-16
Anticipated expiration: 2023-06-30
Also published as: JP2005024350A

Description

【０００１】
【発明の属する技術分野】
本発明は、加速度センサチップが実装された回路基板をケース内に収納した加速度センサに関するものである。
【０００２】
【従来の技術】
一般に加速度センサとして、図４および図５に示すように、加速度を検出するセンサチップ（加速度センサチップ）２が実装された回路基板３をシールドケース１５’内に収納したセンサブロック１７が、ケース１内に収納されたものが提供されている。
【０００３】
ケース１は、図５（ａ）に示すように、外部回路（図示せず）に接続された相手側コネクタ（図示せず）に着脱自在なコネクタ４を備えた基台５と、基台５との間にセンサブロック１７を収納する上面開口の箱状のカバー６とで構成される。センサブロック１７はカバー６に保持されており、カバー６の内周面とセンサブロック１７との間には、ケース１に加わる衝撃がセンサブロック１７に伝わることを防ぐために、ゴム弾性を有する材料からなる緩衝部材９’が介在している。さらに、カバー６に保持されたセンサブロック１７と基台５に設けたコネクタ４とを接続するために、可撓性を有するフレキシブル回路基板１４が設けられている。
【０００４】
一方、センサブロック１７は、図５（ｂ）に示すように、センサチップ２および周辺回路１６（図４参照）の一部が実装された回路基板３をホルダ１８によってシールドケース１５’内に保持する。但し、周辺回路１６においてセンサチップ２にノイズを与える電子部品は、シールドケース１５’内に収納されずに、上述したフレキシブル回路基板１４に実装される。なお、シールドケース１５’は、一端部が回路基板３に接続され他端部がフレキシブル回路基板１４を介してコネクタ４に接続されるリード端子４’を備えたヘッダ１５ａ’と、ヘッダ１５ａ’との間に回路基板３を収納する上面開口の箱状の金属キャン１５ｂ’とで構成される。
【０００５】
ところで、加速度センサを組み立てる際には、センサブロック１７は、ヘッダ１５ａ’を開口面から露出させる形で緩衝部材９’とともにカバー６に挿入される。次に、リード端子４’とコネクタ４とをフレキシブル回路基板１４によって接続するとともに、フレキシブル回路基板１４をＵ字状に湾曲してセンサブロック１７と基台５との間に挟持する形で、基台５とカバー６とが組み合わされる（例えば、特許文献１参照）。
【０００６】
【特許文献１】
特開２００１−１８３３８７号公報（第３−４頁、図２）
【０００７】
【発明が解決しようとする課題】
しかし、上述した構成の加速度センサでは、ケース１内に回路基板３を収納するには、回路基板３をカバー６に収納し、さらに、基台５をカバー６に組み合わせる際にフレキシブル回路基板１４をリード端子４’とコネクタ４との両方に接続することにより回路基板３とコネクタ４とを接続する作業が必要であるので、組立作業が面倒であった。
【０００８】
本発明は、上記事由に鑑みて為されたものであって、組立作業が従来構成に比べて容易な加速度センサを提供することを目的とする。
【０００９】
【課題を解決するための手段】
請求項１の発明は、加速度センサチップが実装された回路基板と、回路基板を収納するケースと、回路基板とケースとの間に挿入されケースから回路基板に伝わる衝撃を吸収する緩衝部材と、ケースに取り付けられ緩衝部材を固定する押さえ板とを備え、ケースが、回路基板を外部回路と接続する端子部を有する基台と、基台とともに回路基板を収納する空間を形成するカバーとからなり、基台が、ケース内に突出し押さえ板が取り付けられる取付脚を備え、押さえ板が、互いに対向する一対の取付片と、両取付片を一体に連結する押さえ片とからなり、取付脚におけるカバーの内側面に夫々対向する側面とカバーの内側面との間に各取付片が挿入され、両取付片の間に取付脚の先端部を挟持する形に配設され、取付片と取付脚との一方に係合突片が突設されるとともに、他方に係合突片と係合する係合孔が形成され、カバーの内側面には、係合突片とは異なる部位で各取付片を取付脚との間に挟持する保持突片が突設されており、緩衝部材は取付脚の先端面と押さえ片との間に挟持されることを特徴とする。
【００１０】
この発明によれば、回路基板は、基台とカバーとを組み合わせる前に、予め押さえ板によって基台に対して固定できるので、ケースを組み立てる際には、基台とカバーとを組み合わせるだけでケース内に回路基板を収納することができ、組立作業が従来構成に比べて容易になる。また、取付片は基台の取付脚から離れる向きの移動を夫々禁止されるので、ケースに衝撃力が作用した場合でも基台から押さえ板が脱落するのを防止できる。
【００１１】
また、請求項２の発明は、請求項１の発明において、前記緩衝部材が、前記回路基板の対向する側縁部に夫々取着され、前記押さえ板は、前記基台との間に緩衝部材を挟持することを特徴とする。
【００１２】
この発明によれば、緩衝部材は、回路基板の対向する側縁部に取着できる大きさであればよいので、回路基板をシールドケース内に収納したセンサブロックを囲む大きさに形成されていた従来構成の緩衝部材に比べて小型化でき、且つ製造コストを抑えられる。
【００１３】
また、請求項３の発明は、請求項１または請求項２の発明において、前記取付脚の先端面は前記ケースの外側面の一部である基準面に対して傾斜した傾斜面であることを特徴とする。
【００１４】
この発明によれば、回路基板を基準面に対して傾斜させるために他の部材を必要としないので、部品点数を抑えることができる。
【００１５】
また、請求項４の発明は、請求項３の発明において、前記カバーは一面開口の箱状であって、前記傾斜面はカバーの底板に対して傾斜し、前記押さえ板はカバーの底板との対向面が傾斜面に沿って傾斜しており、基台とカバーとの逆組み時に押さえ板に当接して逆組みを阻止する逆組阻止突片がカバーの内周面に突設されており、逆組阻止突片は、基台とカバーとの正組み時には押さえ板の傾斜によって押さえ板とカバーの底板との間に形成される隙間に位置することを特徴とする。
【００１６】
この発明によれば、基台とカバーとの組間違いが生じないから、組立の作業性が向上する。
【００１７】
また、請求項５の発明は、請求項１ないし請求項４のいずれかの発明において、前記コネクタが、前記基台から前記カバーと反対方向に突出する端子片と、前記回路基板に接続される接続片と、端子片と接続片とを一体に連結する連結片とを備え、連結片が可撓性を有することを特徴とする。
【００１８】
この発明によれば、基台に加わる衝撃は連結片の可撓性によって吸収されるから、基台から回路基板に衝撃が伝わることを防止できる。
【００２１】
【発明の実施の形態】
以下、本発明の実施形態を図面を参照して説明する。
【００２２】
本実施形態の加速度センサは、図１および図２に示すように、加速度を検出するセンサチップ（加速度センサチップ）２が実装された回路基板３が、ケース１内に収納されて構成される。
【００２３】
ケース１は、図１に示すように、外部回路（図示せず）に接続された相手側コネクタ（図示せず）に着脱自在な端子部としてのコネクタ４を備えた基台５と、基台５との間に回路基板３を収納する空間を形成する上面開口の箱状のカバー６とで構成される。カバー６の内側面には、開口部付近において上部の断面積を下部の断面積より大きくする段差６ｂが形成されており、基台５にカバー６を装置したときに、基台５の周縁部が段差６ｂに当接することによりカバー６が位置決めされる。コネクタ４は、基台５に挿通保持されるコンタクト１９（図２（ａ）参照）と、コンタクト１９の基台５からカバー６と反対方向に突出する部位を囲むように突設される筒状のコネクタハウジング２０とで構成される。
【００２４】
本実施形態は、基台５に設けられた取付脚７と、取付脚７に取り付けられる押さえ板８とを備える。取付脚７は、２枚設けられコンタクト１９の基台５からカバー６の底板６ａ側に突出する部位の周囲に互いに対向する形で突設される。各取付脚７は夫々先端面がカバー６の底板６ａに対して傾斜する傾斜面となった三角形状に形成されている。押さえ板８は、弾性を有し互いに対向する取付片８ａと、両取付片８ａを一体に連結する押さえ片８ｂとで断面コ字状に形成される。ここで、押さえ板８は、各取付片８ａ間の距離を、各取付脚７におけるカバー６の内側面に夫々対向する側面の間の距離に略等しく形成され、両取付片８ａの間に両取付脚７の先端部を挟持する形に配設される。
【００２５】
さらに、各取付脚７における取付片８ａと対向する側面には係合突片１０が夫々（図では２個ずつ）突設され、各取付片８ａには係合突片１０と係合する係合孔１１が夫々（図では２個ずつ）貫設される。各係合突片１０は、取付脚７の先端側の一側面が取付脚７の先端面から離れる程に突出寸法を大きくするように傾斜し、他側面が取付脚７の側面に対して略直交する形に形成される。この構成により、押さえ板８を基台５に取り付ける際には、両取付脚７の先端部を両取付片８ａの間に挿入するように押圧すると、各取付片８ａの弾性により各係合突片１０が各係合孔１１に夫々嵌り込むので、押さえ板８は基台５に対して所謂スナップフィット固定される。また、カバー６の内側面には、図２（ｂ）に示すように、係合突片１０とは異なる部位で各取付片８ａを取付脚７との間に挟持する保持突片１２が突設されており、各取付片８ａは取付脚７から離れる向きの移動を夫々禁止されるので、基台５にカバー６を結合した状態では、係合突片１０が係合孔１１から抜け出すことがなく、基台５から押さえ板８が脱落するのを防止できる。なお、本例では、取付脚７に係合突片１０が設けられ取付片８ａに係合孔１１が設けられているが、取付脚７に係合孔１１を設け取付片８ａに係合突片１０を設ける構成を採用してもよい。
【００２６】
また、カバー６の底板６ａの内面には、図２（ａ）に示すように、基台５に向かって突出する逆組阻止突片１３が設けられている。逆組阻止突片１３は、基台５とカバー６とが逆組みされると押さえ板８に当接し、且つ基台５とカバー６とが正組みされると押さえ板８に当接しない位置および寸法に形成されている。
【００２７】
一方、ケース１に加わる衝撃が回路基板３に伝わるのを防ぐために、加速度センサは、ゴム弾性を有する部材からなる２個の緩衝部材９を有している。各緩衝部材９は夫々、図１に示すように、回路基板３の長手方向の側縁に沿って配設される結合片９ａと、回路基板３の長手方向に隣合う角部に夫々配設されるとともに結合片９ａの両端に夫々結合する２個１組の取着片９ｂとで構成される。各取着片９ｂは、回路基板３の角部の形状に沿って回路基板３の厚さ寸法と略等しい幅寸法で取着溝９ｃが形成されており、回路基板３の角部が取着溝９ｃに挿入されることにより回路基板３の角部に夫々取着される。また、取着溝９ｃの幅方向における各取着片９ｂの寸法は、押さえ板８の押さえ片８ｂと取付脚７の先端面との間の寸法より大きく設計されている。
【００２８】
ここに、回路基板３に取着された各緩衝部材９は、各取付脚７の先端面と押さえ片８ｂとの間に夫々挟持される。したがって、各緩衝部材９は、取着溝９ｃの幅寸法を小さくする向きに圧縮されることにより、回路基板３を夫々挟持する。なお、回路基板３が両取付片８ａの間に各緩衝部材９を夫々介して挟持されるように、両取付片８ａ間の距離を、回路基板３に取着された各緩衝部材９における回路基板３と夫々反対側の側面間の距離と略等しく設計することが望ましい。
【００２９】
また、上述したように、各緩衝部材９は、カバー６の底板６ａに対して傾斜するように形成された取付脚７の先端面に押さえ板８によって夫々固定されるので、カバー６の底板６ａに対して傾斜する。すなわち、各取着溝９ｃ内に夫々角部が挟持される回路基板３はカバー６の底板６ａに対して傾斜するから、回路基板３をカバー６の底板６ａに対して傾斜させるために、他の部材を必要としない。
【００３０】
ところで、基台５に設けたコネクタ４のコンタクト１９は、図２（ａ）に示すように、基台５からカバー６と反対方向に突出し相手側コネクタと接続可能な端子片４ａと、後述するように回路基板３に接続される接続片４ｂと、端子片４ａと接続片４ｂとを一体に連結するとともに可撓性を有する連結片４ｃとで構成される。すなわち、基台５に加わる衝撃は、連結片４ｃの可撓性によって吸収されるので、コネクタ４を介して回路基板３に伝わることが防止される。
【００３１】
なお、本実施形態では、図３に示すように、以下に説明するセンサユニット２１を採用している。センサユニット２１は、内層に接地層３ａを有する多層回路基板からなる回路基板３と、回路基板３との間に回路基板３に実装された電子部品を収納する空間を有する金属製のシールド板１５とで構成される。シールド板１５は、接続端子１５ａが複数個（図では４個）設けられており、各接続端子１５ａが回路基板３において接地層３ａと接続されたスルーホール３ｂに挿通接続されることによって、接地層３ａと電気的に導通している。この構成によって、接地層３ａとシールド板１５とに囲まれた部位の外部で発生するノイズは、接地層３ａおよびシールド板１５によって遮断され接地層３ａとシールド板１５とに囲まれた部位には影響しない。
【００３２】
ここに、センサチップ２と周辺回路１６とが接地層３ａとシールド板１５とで囲まれる部位に実装されることによって、比較的小さい信号を扱うセンサチップ２および周辺回路１６に、外部で発生するノイズが影響することはない。また、外部回路に接続されるコネクタ４のコンタクト１９は、接続片４ａが接地層３ａとシールド板１５とに囲まれる部位を避けて回路基板３に設けられる接続孔３ｃに挿通接続され、接地層３ａとシールド板１５とに囲まれる部位を避けて回路基板３に実装される貫通コンデンサＣ１を介して周辺回路１６に接続される（図２（ａ）参照）。その結果、外部回路からコネクタ４を介して周辺回路１６に供給される信号におけるノイズは、貫通コンデンサＣ１によって遮断されるので、接地層３ａとシールド板１５とに囲まれる部位に影響しない。
【００３３】
上述した加速度センサを組み立てる際には、まず、回路基板３に取着された各緩衝部材９を押さえ片８ｂと取付脚７との間に挟持するように押さえ板８を基台５にスナップフィット固定するとともに、回路基板３とコネクタ４のコンタクト１９とを接続する。次に、基台５とカバー６とを、互いの間に回路基板３を収納する形で組み合わすことによりケース１を構成する。ここで、上述した逆組阻止突片１３によって基台５とカバー６との逆組みが阻止されるので、基台５とカバー６との組間違いが生じない。
【００３４】
【発明の効果】
以上説明したように、本発明では、回路基板は、基台とカバーとを組み合わせる前に、予め押さえ板によって基台に対して固定されるので、ケースを組み立てる際には、基台とカバーとを組み合わせるだけでケース内に回路基板を収納することができ、組立作業が従来構成に比べて容易になる。
【図面の簡単な説明】
【図１】本発明の実施形態を示す分解斜視図である。
【図２】同上を示し、（ａ）は側面断面図、（ｂ）は上面断面図である。
【図３】同上に用いるセンサユニットを示し（ａ）は上面図、（ｂ）は側面図である。
【図４】従来例を示す断面図である。
【図５】（ａ）は同上を示す分解斜視図、（ｂ）は同上の要部を示す分解斜視図である。
【符号の説明】
１ケース
２（加速度）センサチップ
３回路基板
４コネクタ
４ａ端子片
４ｂ接続片
４ｃ連結片
５基台
６カバー
７取付脚
８押さえ板
８ａ取付片
９緩衝部材
１０係合突片
１１係合孔
１２保持突片
１３逆組阻止突片[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an acceleration sensor in which a circuit board on which an acceleration sensor chip is mounted is housed in a case.
[0002]
[Prior art]
In general, as shown in FIGS. 4 and 5, as an acceleration sensor, a sensor block 17 in which a circuit board 3 on which a sensor chip (acceleration sensor chip) 2 for detecting acceleration is mounted is housed in a shield case 15 ′ includes a case 1. What is stored inside is provided.
[0003]
As shown in FIG. 5A, the case 1 includes a base 5 having a connector 4 that is detachable from a mating connector (not shown) connected to an external circuit (not shown), and a base 5 And a box-shaped cover 6 having an upper surface opening for housing the sensor block 17 therebetween. The sensor block 17 is held by the cover 6. A material having rubber elasticity is used between the inner peripheral surface of the cover 6 and the sensor block 17 in order to prevent an impact applied to the case 1 from being transmitted to the sensor block 17. The buffer member 9 ′ is interposed. Furthermore, in order to connect the sensor block 17 held by the cover 6 and the connector 4 provided on the base 5, a flexible circuit board 14 having flexibility is provided.
[0004]
On the other hand, as shown in FIG. 5B, the sensor block 17 holds the circuit board 3 on which the sensor chip 2 and a part of the peripheral circuit 16 (see FIG. 4) are mounted in a shield case 15 ′ by a holder 18. To do. However, an electronic component that gives noise to the sensor chip 2 in the peripheral circuit 16 is mounted on the flexible circuit board 14 described above without being housed in the shield case 15 ′. The shield case 15 ′ has a header 15a ′ having a lead terminal 4 ′ having one end connected to the circuit board 3 and the other end connected to the connector 4 via the flexible circuit board 14, and a header 15a ′. And a box-shaped metal can 15b ′ having an upper surface opening for accommodating the circuit board 3 therebetween.
[0005]
By the way, when the acceleration sensor is assembled, the sensor block 17 is inserted into the cover 6 together with the buffer member 9 ′ so as to expose the header 15a ′ from the opening surface. Next, the lead terminal 4 ′ and the connector 4 are connected by the flexible circuit board 14, and the flexible circuit board 14 is bent in a U shape and sandwiched between the sensor block 17 and the base 5. The stand 5 and the cover 6 are combined (for example, refer to Patent Document 1).
[0006]
[Patent Document 1]
JP 2001-183387 A (page 3-4, FIG. 2)
[0007]
[Problems to be solved by the invention]
However, in the acceleration sensor having the above-described configuration, in order to store the circuit board 3 in the case 1, the circuit board 3 is stored in the cover 6, and the flexible circuit board 14 is mounted when the base 5 is combined with the cover 6. Since it is necessary to connect the circuit board 3 and the connector 4 by connecting to both the lead terminal 4 ′ and the connector 4, the assembly work is troublesome.
[0008]
The present invention has been made in view of the above-described reasons, and an object thereof is to provide an acceleration sensor that can be easily assembled as compared with a conventional configuration.
[0009]
[Means for Solving the Problems]
The invention of claim 1 is a circuit board on which an acceleration sensor chip is mounted; a case that houses the circuit board; a buffer member that is inserted between the circuit board and the case and absorbs an impact transmitted from the case to the circuit board ; A holding plate that is attached to the case and fixes the buffer member , and the case includes a base having a terminal portion that connects the circuit board to an external circuit, and a cover that forms a space for housing the circuit board together with the base. The base includes a mounting leg that protrudes into the case and to which the pressing plate is attached, and the pressing plate includes a pair of mounting pieces facing each other and a pressing piece that integrally connects both mounting pieces, and covers the mounting leg. Each mounting piece is inserted between a side surface facing the inner side surface of the cover and the inner side surface of the cover, and the tip of the mounting leg is sandwiched between the two mounting pieces. One side of The projecting piece protrudes, and the other is formed with an engaging hole for engaging with the engaging projecting piece, and each mounting piece is attached to the mounting leg at a site different from the engaging projecting piece on the inner surface of the cover. A holding projecting piece sandwiched therebetween is projected, and the buffer member is sandwiched between the tip end surface of the mounting leg and the pressing piece .
[0010]
According to the present invention, the circuit board can be fixed to the base in advance by the pressing plate before combining the base and the cover. Therefore, when assembling the case, the base board and the cover are simply combined. The circuit board can be accommodated therein, and the assembling work becomes easier as compared with the conventional configuration. In addition, since the attachment pieces are prohibited from moving away from the attachment legs of the base, it is possible to prevent the pressing plate from dropping from the base even when an impact force is applied to the case.
[0011]
According to a second aspect of the present invention, in the first aspect of the present invention, the buffer member is attached to each of opposite side edge portions of the circuit board, and the pressing plate is disposed between the base and the buffer member. It is characterized by pinching.
[0012]
According to the present invention, the buffer member may be of a size that can be attached to the opposite side edge portions of the circuit board, and thus is formed in a size surrounding the sensor block in which the circuit board is housed in the shield case. The size can be reduced as compared with the buffer member having the conventional configuration, and the manufacturing cost can be reduced.
[0013]
According to a third aspect of the present invention, in the first or second aspect of the invention, the front end surface of the mounting leg is an inclined surface inclined with respect to a reference surface that is a part of the outer surface of the case. Features.
[0014]
According to the present invention, since no other member is required to incline the circuit board with respect to the reference plane, the number of components can be suppressed.
[0015]
According to a fourth aspect of the present invention, in the third aspect of the present invention, the cover is a box having a single opening, the inclined surface is inclined with respect to the bottom plate of the cover, and the pressing plate is connected to the bottom plate of the cover. The opposing surface is inclined along the inclined surface, and a reverse assembly blocking protrusion that protrudes against the holding plate and prevents reverse assembly when the base and cover are reversely assembled protrudes from the inner peripheral surface of the cover The reverse assembly blocking protrusion is characterized in that it is located in a gap formed between the press plate and the bottom plate of the cover by the inclination of the press plate when the base and the cover are normally assembled .
[0016]
According to the present invention, there is no mistake in assembling the base and the cover, so that assembly workability is improved.
[0017]
According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the connector is connected to the terminal board projecting from the base in a direction opposite to the cover, and to the circuit board. A connection piece and a connection piece for connecting the terminal piece and the connection piece integrally are provided, and the connection piece has flexibility.
[0018]
According to the present invention, since the impact applied to the base is absorbed by the flexibility of the connecting piece, it is possible to prevent the impact from being transmitted from the base to the circuit board.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0022]
As shown in FIGS. 1 and 2, the acceleration sensor of the present embodiment is configured by housing a circuit board 3 on which a sensor chip (acceleration sensor chip) 2 for detecting acceleration is mounted in a case 1.
[0023]
As shown in FIG. 1, the case 1 includes a base 5 having a connector 4 as a terminal portion detachable from a mating connector (not shown) connected to an external circuit (not shown), and a base 5 and a box-shaped cover 6 having an upper surface opening that forms a space for housing the circuit board 3. On the inner side surface of the cover 6, a step 6 b is formed in the vicinity of the opening so that the upper cross-sectional area is larger than the lower cross-sectional area, and when the cover 6 is installed on the base 5, the peripheral edge of the base 5 The cover 6 is positioned by contacting the step 6b. The connector 4 protrudes so as to surround a contact 19 inserted and held in the base 5 (see FIG. 2A) and a portion of the contact 19 that protrudes from the base 5 in the direction opposite to the cover 6. Connector housing 20.
[0024]
This embodiment includes a mounting leg 7 provided et the the base 5, and a retainer plate 8 attached to the attachment leg 7. Two mounting legs 7 are provided so as to be opposed to each other around a portion protruding from the base 5 of the contact 19 toward the bottom plate 6 a of the cover 6. Each mounting leg 7 is formed in a triangular shape in which the tip surface is an inclined surface inclined with respect to the bottom plate 6 a of the cover 6. The presser plate 8 is formed in a U-shaped cross section with an attachment piece 8a having elasticity and facing each other, and a presser piece 8b integrally connecting the two attachment pieces 8a. Here, the holding plate 8 is formed so that the distance between the mounting pieces 8a is substantially equal to the distance between the side surfaces of the mounting legs 7 facing the inner side surface of the cover 6, and between the mounting pieces 8a. The tip of the mounting leg 7 is disposed so as to be sandwiched.
[0025]
Further, engaging projections 10 are respectively provided on the side surfaces of the mounting legs 7 facing the mounting pieces 8a ( two in the drawing), and each mounting piece 8a is engaged with the engaging protrusion 10. Each of the engagement holes 11 is provided (two in the figure). Each engaging protrusion 10 is inclined so that one side surface of the front end side of the mounting leg 7 becomes larger as the protrusion dimension increases as the distance from the front end surface of the mounting leg 7 increases. It is formed in an orthogonal shape. With this configuration, when the presser plate 8 is attached to the base 5, if the tip ends of the two attachment legs 7 are pressed so as to be inserted between the two attachment pieces 8 a, the engagement protrusions 8 a are elastically engaged with each engagement protrusion. Since the pieces 10 are fitted into the respective engagement holes 11, the presser plate 8 is so-called snap-fit fixed to the base 5. Further, as shown in FIG. 2 (b), holding protrusions 12 that hold the attachment pieces 8 a between the attachment legs 7 at portions different from the engagement protrusions 10 protrude from the inner surface of the cover 6. Since each of the mounting pieces 8a is prohibited from moving away from the mounting leg 7, the engaging protrusion 10 is pulled out of the engaging hole 11 when the cover 6 is coupled to the base 5. The presser plate 8 can be prevented from falling off from the base 5. In this example, the engagement protrusion 10 is provided on the attachment leg 7 and the engagement hole 11 is provided on the attachment piece 8a. However, the engagement hole 11 is provided on the attachment leg 7 and the engagement protrusion 8a is engaged. A configuration in which the piece 10 is provided may be employed.
[0026]
Further, as shown in FIG. 2 (a), a reverse assembly blocking protrusion 13 that protrudes toward the base 5 is provided on the inner surface of the bottom plate 6 a of the cover 6. The reverse assembly blocking protrusion 13 is in contact with the holding plate 8 when the base 5 and the cover 6 are reversely assembled, and is not in contact with the holding plate 8 when the base 5 and the cover 6 are assembled together. And are formed to dimensions.
[0027]
On the other hand, in order to prevent the impact applied to the case 1 from being transmitted to the circuit board 3, the acceleration sensor has two buffer members 9 made of rubber elastic members. As shown in FIG. 1, each buffer member 9 is disposed at a coupling piece 9 a disposed along a side edge in the longitudinal direction of the circuit board 3 and a corner portion adjacent to the circuit board 3 in the longitudinal direction. And a set of two attachment pieces 9b respectively connected to both ends of the connection piece 9a. Each attachment piece 9b is formed with an attachment groove 9c having a width dimension substantially equal to the thickness dimension of the circuit board 3 along the shape of the corner part of the circuit board 3, and the corner part of the circuit board 3 is attached to the attachment part 9b. By being inserted into the grooves 9c, they are respectively attached to the corners of the circuit board 3. Further, the dimension of each attachment piece 9 b in the width direction of the attachment groove 9 c is designed to be larger than the dimension between the holding piece 8 b of the holding plate 8 and the tip surface of the mounting leg 7.
[0028]
Here, each buffer member 9 attached to the circuit board 3 is sandwiched between the tip surface of each mounting leg 7 and the pressing piece 8b. Therefore, each buffer member 9 holds the circuit board 3 by being compressed in a direction to reduce the width dimension of the attachment groove 9c. It should be noted that the distance between the mounting pieces 8a is set to a circuit in each buffer member 9 attached to the circuit board 3 so that the circuit board 3 is sandwiched between the mounting pieces 8a. It is desirable to design the distance approximately equal to the distance between the substrate 3 and the opposite side surface.
[0029]
Further, as described above, each buffer member 9 is fixed to the front end surface of the mounting leg 7 formed so as to be inclined with respect to the bottom plate 6 a of the cover 6 by the pressing plate 8, and therefore the bottom plate 6 a of the cover 6. Tilt against. That is, since the circuit board 3 in which the corners are sandwiched in the respective attachment grooves 9c is inclined with respect to the bottom plate 6a of the cover 6, in order to incline the circuit board 3 with respect to the bottom plate 6a of the cover 6, The member of is not required.
[0030]
By the way, as shown in FIG. 2A, the contact 19 of the connector 4 provided on the base 5 projects from the base 5 in the opposite direction to the cover 6 and can be connected to the mating connector, as will be described later. Thus, the connection piece 4b connected to the circuit board 3, and the terminal piece 4a and the connection piece 4b are integrally connected to each other, and the connection piece 4c is flexible. That is, since the impact applied to the base 5 is absorbed by the flexibility of the connecting piece 4 c, it is prevented from being transmitted to the circuit board 3 through the connector 4.
[0031]
In this embodiment, as shown in FIG. 3, a sensor unit 21 described below is employed. The sensor unit 21 includes a circuit board 3 formed of a multilayer circuit board having a ground layer 3 a as an inner layer, and a metal shield plate 15 having a space for storing electronic components mounted on the circuit board 3 between the circuit board 3. It consists of. The shield plate 15 is provided with a plurality of connection terminals 15a (four in the figure), and each connection terminal 15a is inserted into and connected to a through hole 3b connected to the ground layer 3a in the circuit board 3, thereby connecting the shield plate 15. It is electrically connected to the formation 3a. With this configuration, noise generated outside the portion surrounded by the ground layer 3a and the shield plate 15 is blocked by the ground layer 3a and the shield plate 15 and is not surrounded by the portion surrounded by the ground layer 3a and the shield plate 15. It does not affect.
[0032]
Here, the sensor chip 2 and the peripheral circuit 16 are mounted on a portion surrounded by the ground layer 3a and the shield plate 15, so that the sensor chip 2 and the peripheral circuit 16 that handle relatively small signals are generated externally. Noise is not affected. Further, the contact 19 of the connector 4 connected to the external circuit is inserted and connected to a connection hole 3c provided in the circuit board 3 so as to avoid a portion where the connection piece 4a is surrounded by the ground layer 3a and the shield plate 15, It is connected to the peripheral circuit 16 via a feedthrough capacitor C1 mounted on the circuit board 3 while avoiding a portion surrounded by 3a and the shield plate 15 (see FIG. 2A). As a result, noise in the signal supplied from the external circuit to the peripheral circuit 16 via the connector 4 is blocked by the feedthrough capacitor C1, and thus does not affect the portion surrounded by the ground layer 3a and the shield plate 15.
[0033]
When assembling the acceleration sensor described above, first, the presser plate 8 is snap-fit to the base 5 so that each buffer member 9 attached to the circuit board 3 is sandwiched between the presser piece 8 b and the mounting leg 7. While fixing, the circuit board 3 and the contact 19 of the connector 4 are connected. Next, the case 1 is configured by combining the base 5 and the cover 6 so as to accommodate the circuit board 3 between them. Here, since the reverse assembly prevention protrusion 13 prevents the reverse assembly of the base 5 and the cover 6, no erroneous assembly of the base 5 and the cover 6 occurs.
[0034]
【The invention's effect】
As described above, in the present invention, the circuit board is fixed to the base by the holding plate in advance before combining the base and the cover. Therefore, when assembling the case, the base and the cover The circuit board can be accommodated in the case simply by combining the two, and the assembling work becomes easier as compared with the conventional configuration.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing an embodiment of the present invention.
2A is a side sectional view, and FIG. 2B is a top sectional view.
3A is a top view of the sensor unit used in the above, and FIG. 3B is a side view thereof.
FIG. 4 is a cross-sectional view showing a conventional example.
5A is an exploded perspective view showing the same as above, and FIG. 5B is an exploded perspective view showing the main part of the same.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Case 2 (acceleration) sensor chip 3 Circuit board 4 Connector 4a Terminal piece 4b Connection piece 4c Connection piece 5 Base 6 Cover 7 Attachment leg 8 Holding plate 8a Attachment piece 9 Buffer member 10 Engagement protrusion 11 Engagement hole 12 Holding Projection 13 Reverse Assembly Blocking Projection

Claims

A circuit board on which the acceleration sensor chip is mounted; a case that houses the circuit board; a buffer member that is inserted between the circuit board and the case and absorbs an impact transmitted from the case to the circuit board; and a buffer member that is attached to the case. The case includes a base having a terminal portion that connects the circuit board to an external circuit, and a cover that forms a space for housing the circuit board together with the base. The holding plate includes a pair of mounting pieces that are opposed to each other and a holding piece that integrally connects the two mounting pieces, and faces the inner surface of the cover of the mounting leg. Each mounting piece is inserted between the side surface and the inner side surface of the cover, and the tip of the mounting leg is sandwiched between the mounting pieces, and the engaging protrusion on one of the mounting piece and the mounting leg. Is projected Both are provided with an engagement hole that engages with the engagement projection piece on the other side, and a holding projection piece that holds each attachment piece between the attachment leg at a location different from the engagement projection piece on the inner side surface of the cover Is provided, and the shock-absorbing member is sandwiched between the tip end surface of the mounting leg and the pressing piece .

2. The acceleration sensor according to claim 1, wherein the buffer member is attached to opposite side edge portions of the circuit board, and the pressing plate sandwiches the buffer member between the base plate and the base plate.

The acceleration sensor according to claim 1, wherein the front end surface of the mounting leg is an inclined surface that is inclined with respect to a reference surface that is a part of the outer surface of the case .

The cover has a box shape with an opening on one side, the inclined surface is inclined with respect to the bottom plate of the cover, and the holding plate is inclined with respect to the bottom plate of the cover along the inclined surface, A reverse assembly blocking protrusion is provided on the inner peripheral surface of the cover to prevent reverse assembly by abutting against the holding plate during reverse assembly with the cover. 4. The acceleration sensor according to claim 3, wherein the acceleration sensor is located in a gap formed between the presser plate and the bottom plate of the cover sometimes due to the inclination of the presser plate .

The terminal portion includes a terminal piece protruding from the base in a direction opposite to the cover, a connection piece connected to the circuit board, and a connection piece that integrally connects the terminal piece and the connection piece. acceleration sensor according to any one of claims 1 to 4, characterized in that the piece flexible.