JP3823234B2 - Load cell - Google Patents

Load cell Download PDF

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Publication number
JP3823234B2
JP3823234B2 JP33649296A JP33649296A JP3823234B2 JP 3823234 B2 JP3823234 B2 JP 3823234B2 JP 33649296 A JP33649296 A JP 33649296A JP 33649296 A JP33649296 A JP 33649296A JP 3823234 B2 JP3823234 B2 JP 3823234B2
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JP
Japan
Prior art keywords
circuit board
load cell
printed circuit
flexible printed
reinforcing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP33649296A
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Japanese (ja)
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JPH10176964A (en
Inventor
明生 広瀬
英裕 宮本
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Yamato Scale Co Ltd
Original Assignee
Yamato Scale Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Yamato Scale Co Ltd filed Critical Yamato Scale Co Ltd
Priority to JP33649296A priority Critical patent/JP3823234B2/en
Publication of JPH10176964A publication Critical patent/JPH10176964A/en
Application granted granted Critical
Publication of JP3823234B2 publication Critical patent/JP3823234B2/en
Anticipated expiration legal-status Critical
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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/14—Structural association of two or more printed circuits
    • H05K1/144—Stacked arrangements of planar printed circuit boards
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/18—Printed circuits structurally associated with non-printed electric components
    • H05K1/189—Printed circuits structurally associated with non-printed electric components characterised by the use of a flexible or folded printed circuit
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/0058—Laminating printed circuit boards onto other substrates, e.g. metallic substrates

Description

【０００１】
【発明の属する技術分野】
この発明は、温度補償回路、Ａ／Ｄ変換回路、増幅回路等の電気回路部をプリント基板として具備したロードセルに関する。
【０００２】
【従来の技術】
近年のロードセルにおける配線方法としては、ケーブルの長さが短縮でき且つロードセル自体の温度特性も安定することからストレインゲージ近くまで延伸させたフレキシブルプリント基板が多く用いられている。又このロードセルに必要な電気的機能を搭載した基板も備えられるようになった。図２に従来の電気回路部基板を直接弾性体上のフレキシブルプリント基板に接続したロバーバル型ロードセルを示す。この図において１はロードセル本体、２は起歪部、３は剛体部、４は入出力の配線としてのフレキシブルプリント基板で、一般に樹脂製ベース材料の上に銅箔６による導体膜を形成し、これを更に樹脂材料でオーバーコーティングされている。７は電気回路部と接続する端子で、８は上記起歪部２上の４ヶ所に貼付されたストレインゲージで、上記フレキシブルプリント基板４の銅箔６に接続されている。９は両面接着用テープで片面はフレキシブルプリント基板へもう一方の面は電気回路部基板１０に貼着され、上記電気回路部基板はロードセルの歪み特性を乱さないために剛体部３の位置に貼付されている。又１１は電気回路部基板の脚で上記フレキシブルプリント基板の端子７と入出力線１５にそれぞれ接続されている。しかし、低原価を目的とするために上記のように電気回路基板１０を両面接着用テープによりロードセル本体の剛体部３に貼付されているが、電気回路部基板には種々の部品が取り付けられているので激しい凹凸面を持っている。従って両面接着用テープでの貼付では良好な密着性が確保できないという問題がある。図３はロバーバル型ロードセルに偏荷重が作用したときの図である。図に示すようにロバーバル型ロードセル１の一端をロードセル取付台２０に固定し、他端に載台１６を取り付け、この載台１６の左右端のいずれかに重り１７を載せる。重りの重量が矢印１８の方向に作用するものとすると該ロードセルには矢印１９のねじれモーメントが生ずる。重りの重量がロードセルの定格荷重に近い場合やそれを越えるような場合には矢印１９のモーメントは大きくなり、該ロードセルの固定側の剛体部３にも微少の変形が生ずる。特に材料コストの削減でロードセル全体がコンパクトに設計されている場合には特にこの傾向が強い。従って上記電気回路部基板がこの変形を受けたときは回路内の動作に支障が生ずるという問題がある。又、上記電気回路部はロードセルに貼付される前に単独で検査機械にかけられて動作確認が行われ良品のみが使用されるが、外部に引き出す信号線は直接この電気回路部に接続されているので、この信号線に加えられた外力が電気回路部に伝わることになり、電気回路内の動作に支障が生ずるという問題もある。
【０００３】
【発明が解決しようとする課題】
そこでこの発明は、前記の問題点を解決するために電気回路部基板をフレキシブルプリント基板に接続するとき、ロードセル剛体部に微少な変形が起こっても電気回路部が変形を起こさず安定した動作が発揮できるように簡単で確実な装置を備えたロードセルを提供しようとするものである。
【０００４】
【課題を解決するための手段】
上記の課題を達成するために、この発明は、起歪部にストレインゲージを貼付したロードセルにおいて、上記ストレインゲージに接続された導体パターンを展開したフレキシブルプリント基板をロードセル本体に貼付し、ロードセルの剛体部に貼付された上記フレキシブルプリント基板部分に両面接着用テープを貼着し、その上に補強用プリント基板を貼付し、更にその上に脚を上記補強用プリント基板のスルーホールを介してフレキシブルプリント基板の接点に接続するようにして温度補償回路、Ａ／Ｄ変換回路、増幅回路、安定化電源回路等を備えた電気回路部基板の導体部を経由して上記電気回路部基板に接続するように構成したものである。
【０００５】
【発明の実施の形態】
この発明によれば、電気回路部基板を補強用プリント基板のスルーホールに確実に半田付けにすることにより補強用プリント基板と電気回路部が確実に接続され、又平面性の良い上記補強用プリント基板をロードセルの剛体部に両面接着用テープにて貼付することで補強用プリント基板とロードセルとは密着される。従って電気回路部もロードセルに確実に接着されることになる。更に電気回路部からの信号は上記補強用プリント基板の導体部を経由して入出力線にて外部に接続されるがこの線に外力がかかったときでも電気回路部が安定な動作をするので正確な計量が可能となる。
【０００６】
【実施例】
本発明の実施例をロバーバル型ロードセルに適用した組み立て斜視図を図１に示す。この図において、１はロードセル本体、２は４ヶ所設けられた起歪部、３は計量器のベースに固定される剛体部、４は出入力の配線としてのフレキシブルプリント基板で、一般に耐熱ポリエステル、ポリイミド等の樹脂製ベース材料の上に銅箔６による導体膜を形成し、これをまた樹脂材料でオーバーコーティングされている。７は電気回路部と接続する端子で上記ロードセルの剛体部の側面上部となるよう配置されている。８は上記起歪部２の上面２ヶ下面２ヶの合計４ヶのストレインゲージで、上記フレキシブルプリント基板４の上下の銅箔６にそれぞれ接続されている。９は両面テープで片面はフレキシブルプリント基板４の剛体部の側面へ貼付された部分へ、もう一方は本発明の主要部である補強用プリント基板１２に貼付されている。１０は温度補償回路、Ａ／Ｄ変換回路、増幅回路、安定化電源回路等を備えた電気回路部のプリント基板で、この脚１１は上記補強用プリント基板１２に設けられたスルーホール１３を介して上記フレキシブルプリント基板４の接点７に半田により固定されている。１５は入出力線で補強用プリント基板１２の導体部１４を経由して電気回路部に接続されている。従ってロードセルに偏荷重が負荷され剛体部３に微少な変形が生じても補強用プリント基板１２によりその影響が遮断されて電気回路部まで悪い影響を与えることはない。又平面性のあるロードセルの剛体部３と同じく平面性のある補強用プリント基板１２とが両面テープ９を介して結合されるので安定した密着性を得ることができる。又入出力線のケーブルを動かしても電気回路部まで悪い影響を与えることもない。
【０００７】
【発明の効果】
この発明によれば、ロードセルに各種信号処理機能を有した電気回路部基板を貼付する際、補強用プリント基板を設け、この基板を介してロードセルの剛体部に取り付けているので、ロードセルに大きな偏荷重が負荷され上記剛体部に微少変形が生じても、基板上の電気回路部に悪影響を与えることがなく安定した動作により正確な計量ができるという効果がある。
【図面の簡単な説明】
【図１】この発明の実施例になるロバーバル型ロードセルの組み立て斜視図である。
【図２】従来のロバーバル型ロードセルの組み立て斜視図である。
【図３】ロードセルに偏荷重が負荷されるときの図である。
【符号の説明】
１ ロードセル本体
２ 起歪部
３ 剛体部
４ フレキシブルプリント基板
５ 樹脂製ベース材料
６ 銅箔
７ 端子
８ ストレインゲージ
９ 両面テープ
１０ 電気回路部基板
１１ 電気回路部基板の脚
１２ 補強用プリント基板
１３ スルーホール
１４ 補強用プリント基板の導体部
１５ 入出力線[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a load cell including an electric circuit section such as a temperature compensation circuit, an A / D conversion circuit, and an amplifier circuit as a printed circuit board.
[0002]
[Prior art]
As a wiring method in a load cell in recent years, a flexible printed circuit board extended to near a strain gauge is often used because the cable length can be shortened and the temperature characteristics of the load cell itself are stabilized. In addition, a substrate on which an electrical function necessary for the load cell is mounted can be provided. FIG. 2 shows a Robert load cell in which a conventional electric circuit board is directly connected to a flexible printed circuit board on an elastic body. In this figure, 1 is a load cell body, 2 is a strain generating portion, 3 is a rigid body portion, 4 is a flexible printed circuit board as input / output wiring, and a conductor film made of copper foil 6 is generally formed on a resin base material. This is further overcoated with a resin material. 7 is a terminal connected to the electric circuit portion, and 8 is a strain gauge affixed at four locations on the strain generating portion 2 and is connected to the copper foil 6 of the flexible printed circuit board 4. 9 is a double-sided adhesive tape, one side is attached to the flexible printed circuit board and the other side is attached to the electric circuit board 10, and the electric circuit board is attached to the position of the rigid part 3 so as not to disturb the distortion characteristics of the load cell. Has been. Reference numeral 11 denotes a leg of the electric circuit board, which is connected to the terminal 7 and the input / output line 15 of the flexible printed board. However, in order to reduce the cost, the electric circuit board 10 is attached to the rigid body portion 3 of the load cell main body with the double-sided adhesive tape as described above, but various parts are attached to the electric circuit board. Because it has a severe uneven surface. Therefore, there is a problem that good adhesion cannot be ensured by sticking with a double-sided adhesive tape. FIG. 3 is a diagram when an unbalanced load is applied to the Rovalval type load cell. As shown in the figure, one end of the robust load cell 1 is fixed to the load cell mounting base 20, the mounting base 16 is attached to the other end, and a weight 17 is placed on either the left or right end of the mounting base 16. Assuming that the weight weight acts in the direction of arrow 18, a torsional moment of arrow 19 is generated in the load cell. When the weight weight is close to or exceeds the rated load of the load cell, the moment of the arrow 19 increases, and a slight deformation occurs in the rigid portion 3 on the fixed side of the load cell. This tendency is particularly strong when the entire load cell is designed to be compact in order to reduce material costs. Therefore, when the electric circuit board is subjected to this deformation, there is a problem that the operation in the circuit is hindered. In addition, the above-mentioned electric circuit section is applied to the inspection machine alone before being attached to the load cell, the operation is confirmed, and only non-defective products are used. However, the signal line drawn out is directly connected to this electric circuit section. Therefore, the external force applied to the signal line is transmitted to the electric circuit unit, which causes a problem that the operation in the electric circuit is hindered.
[0003]
[Problems to be solved by the invention]
Therefore, in the present invention, when the electric circuit board is connected to the flexible printed circuit board in order to solve the above-described problems, even if a slight deformation occurs in the rigid body of the load cell, the electric circuit does not deform and the stable operation is achieved. It is an object of the present invention to provide a load cell having a simple and reliable device that can be used.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, in a load cell in which a strain gauge is attached to a strain generating portion, a flexible printed circuit board in which a conductor pattern connected to the strain gauge is developed is attached to a load cell body, and a rigid body of the load cell A double-sided adhesive tape is affixed to the flexible printed circuit board part that is affixed to the part, a reinforcing printed circuit board is affixed thereon, and a leg is then printed on the flexible printed circuit board through the through hole of the reinforcing printed circuit board. Connected to the electrical circuit board via the conductor part of the electrical circuit board provided with a temperature compensation circuit, an A / D conversion circuit, an amplifier circuit, a stabilized power supply circuit, etc. It is configured.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
According to this invention, the reinforcing printed circuit board and the electric circuit section are securely connected by reliably soldering the electric circuit section board to the through hole of the reinforcing printed circuit board, and the reinforcing printed board having good flatness is provided. The printed circuit board for reinforcement and the load cell are brought into close contact with each other by sticking the substrate to the rigid portion of the load cell with a double-sided adhesive tape. Therefore, the electric circuit portion is also securely bonded to the load cell. Furthermore, the signal from the electric circuit section is connected to the outside via an input / output line via the conductor section of the reinforcing printed circuit board, but the electric circuit section operates stably even when an external force is applied to this line. Accurate weighing is possible.
[0006]
【Example】
FIG. 1 shows an assembled perspective view in which an embodiment of the present invention is applied to a Robert type load cell. In this figure, 1 is a load cell main body, 2 is a strain generating portion provided at four places, 3 is a rigid body portion fixed to the base of a measuring instrument, 4 is a flexible printed circuit board as an input / output wiring, generally heat resistant polyester, A conductor film made of copper foil 6 is formed on a resin base material such as polyimide, and this is also overcoated with a resin material. Reference numeral 7 denotes a terminal connected to the electric circuit portion, which is arranged to be an upper part of the side surface of the rigid body portion of the load cell. Reference numeral 8 denotes a total of four strain gauges, the upper surface 2 and the lower surface 2 of the strain generating portion 2, which are connected to the upper and lower copper foils 6 of the flexible printed board 4, respectively. Reference numeral 9 denotes a double-sided tape, one side of which is attached to the side of the rigid body portion of the flexible printed circuit board 4, and the other is attached to the reinforcing printed circuit board 12 which is the main part of the present invention. Reference numeral 10 denotes a printed circuit board of an electric circuit section provided with a temperature compensation circuit, an A / D conversion circuit, an amplifier circuit, a stabilized power supply circuit, etc. This leg 11 is connected through a through hole 13 provided in the reinforcing printed circuit board 12. The flexible printed circuit board 4 is fixed to the contact 7 by soldering. An input / output line 15 is connected to the electric circuit portion via the conductor portion 14 of the reinforcing printed circuit board 12. Therefore, even if an eccentric load is applied to the load cell and a slight deformation occurs in the rigid body portion 3, the influence is blocked by the reinforcing printed circuit board 12, and the electric circuit portion is not adversely affected. In addition, since the rigid portion 3 of the load cell having flatness and the reinforcing printed circuit board 12 having flatness are coupled via the double-sided tape 9, stable adhesion can be obtained. Also, moving the input / output cable does not adversely affect the electrical circuit.
[0007]
【The invention's effect】
According to the present invention, when the electric circuit board having various signal processing functions is attached to the load cell, the reinforcing printed circuit board is provided and attached to the rigid body of the load cell via this board. Even if a load is applied and the rigid body portion is slightly deformed, there is an effect that accurate measurement can be performed by a stable operation without adversely affecting the electric circuit portion on the substrate.
[Brief description of the drawings]
FIG. 1 is an assembled perspective view of a robust load cell according to an embodiment of the present invention.
FIG. 2 is an assembled perspective view of a conventional robust valve.
FIG. 3 is a diagram when an unbalanced load is applied to the load cell.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Load cell main body 2 Strain part 3 Rigid part 4 Flexible printed circuit board 5 Resin base material 6 Copper foil 7 Terminal 8 Strain gauge 9 Double-sided tape 10 Electric circuit board 11 Leg of electric circuit board 12 Reinforcement printed board 13 Through hole 14 Reinforced printed circuit board conductor 15 Input / output line

Claims (1)

起歪体にストレインゲージを貼付したロードセルにおいて、導体パターンに展開され上記ストレインゲージに接続されており、ロードセル本体に貼付されたフレキシブルプリント基板の接続部と、該接続部に接続されるスルーホールを有し外部接続用導体パターンを有する補強用プリント基板と、上記フレキシブルプリント基板の接続部と上記補強用プリント基板との間に介在し両者を接着する接着部材と、脚が上記補強用プリント基板のスルーホールを介して上記フレキシブルプリント基板の接続部に接続されるようになっており、温度補償回路、Ａ／Ｄ変換回路、増幅回路、安定化電源回路等を備えた各種信号処理機能を有する電気回路部のプリント基板とで構成され、偏荷重によりロードセルの剛体部に微少な変形が生じても、上記電気回路部の安定した動作により正確な計量値が得られることを特徴とするロードセル。In a load cell in which a strain gauge is attached to a strain generating body, the conductive pattern is developed and connected to the strain gauge, and a connection portion of a flexible printed circuit board attached to the load cell body and a through hole connected to the connection portion are provided. A reinforcing printed circuit board having a conductor pattern for external connection, an adhesive member interposed between and bonded to the connecting portion of the flexible printed circuit board and the reinforcing printed circuit board, and a leg of the reinforcing printed circuit board Electricity having various signal processing functions including a temperature compensation circuit, an A / D conversion circuit, an amplifier circuit, a stabilized power supply circuit, and the like, which is connected to the connecting portion of the flexible printed circuit board through a through hole. Even if a slight deformation occurs in the rigid body of the load cell due to an unbalanced load, Load cell, characterized in that accurate weighing result obtained by the stable operation of the circuit portion.
JP33649296A 1996-12-17 1996-12-17 Load cell Expired - Lifetime JP3823234B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP33649296A JP3823234B2 (en) 1996-12-17 1996-12-17 Load cell

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP33649296A JP3823234B2 (en) 1996-12-17 1996-12-17 Load cell

Publications (2)

Publication Number Publication Date
JPH10176964A JPH10176964A (en) 1998-06-30
JP3823234B2 true JP3823234B2 (en) 2006-09-20

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
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Country Status (1)

Country Link
JP (1) JP3823234B2 (en)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001343294A (en) * 2000-05-31 2001-12-14 Ishida Co Ltd Load cell and balance
AU2001292095A1 (en) * 2000-10-05 2002-04-15 Industrial Dataloggers Limited Strain gauge devices
JP4743959B2 (en) * 2000-12-26 2011-08-10 大和製衡株式会社 Load cell
JP4887260B2 (en) * 2006-10-31 2012-02-29 アイシン精機株式会社 Passenger load sensor for vehicle seat
US8215178B2 (en) 2007-05-02 2012-07-10 Flexco Industries Inc. Sensor device to monitor deformation in structural members, such as solid structures
JP2009053005A (en) * 2007-08-27 2009-03-12 Hitachi Metals Ltd Semiconductor strain sensor, and mounting method of semiconductor strain sensor
JP5487672B2 (en) * 2009-03-27 2014-05-07 パナソニック株式会社 Physical quantity sensor
JP6632817B2 (en) * 2015-06-25 2020-01-22 大和製衡株式会社 Parallelogram load cell
JP7074407B2 (en) * 2017-09-19 2022-05-24 ミネベアミツミ株式会社 Force sensor device
CN109989229A (en) * 2018-01-02 2019-07-09 合肥日上电器股份有限公司 A kind of water level sensor
JP2023056768A (en) * 2021-10-08 2023-04-20 日本電産コパル電子株式会社 sensor

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