EP1151259A1 - Element d'equilibrage pour un capteur - Google Patents

Element d'equilibrage pour un capteur

Info

Publication number
EP1151259A1
EP1151259A1 EP00906275A EP00906275A EP1151259A1 EP 1151259 A1 EP1151259 A1 EP 1151259A1 EP 00906275 A EP00906275 A EP 00906275A EP 00906275 A EP00906275 A EP 00906275A EP 1151259 A1 EP1151259 A1 EP 1151259A1
Authority
EP
European Patent Office
Prior art keywords
trimming
resistance
resistors
adjustment
element according
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.)
Withdrawn
Application number
EP00906275A
Other languages
German (de)
English (en)
Inventor
Helmut Burfeindt
Martin Hauber
Wolfgang Bauch
Ursula Host
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.)
Hottinger Bruel and Kjaer GmbH
Original Assignee
Hottinger Baldwin Messtechnik GmbH
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 Hottinger Baldwin Messtechnik GmbH filed Critical Hottinger Baldwin Messtechnik GmbH
Publication of EP1151259A1 publication Critical patent/EP1151259A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D3/00—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups
    • G01D3/028—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure
    • G01D3/036—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure on measuring arrangements themselves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D3/00—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups
    • G01D3/028—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
    • G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
    • G01L1/2268—Arrangements for correcting or for compensating unwanted effects
    • G01L1/2281—Arrangements for correcting or for compensating unwanted effects for temperature variations

Definitions

  • the invention relates to a balancing element for a sensor according to the preamble of patent claim 1.
  • Such adjustment elements for transducers are used to compensate the temperature response of transducer circuits with strain gauges. These are particularly intended for load cells and other force and pressure transducers. The temperature response of such is understood here
  • Measuring point is the temperature-dependent change in the measuring signal despite complete absence (TKO) or complete constancy (TKK) of a mechanical load on the test object.
  • a temperature response can occur if the temperature of the sensor or its surroundings changes during the observation period.
  • the cause of such a temperature response can be the thermal expansion of the transducer material, the thermal expansion of the measuring grid material of the strain gauges and the temperature coefficient of the electrical resistance.
  • a measurement in which the test object experiences a change in temperature during mechanical stress provides the result of the sum of the mechanical strain and the thermal strain.
  • the thermal component of the strain indicator is included as an error.
  • balancing element It is known to largely compensate for this error by means of a balancing element. It is important that these balancing elements are also temperature-dependent in order to be able to largely correct the influence of temperature on the sensor.
  • circuits with trimming resistances in the feed lines and trimming resistors in the bridge branches are provided, with which the bridge is trimmed at different temperatures without and under load. Since these balancing circuits must always be arranged near the transducers for thermal reasons, these circuits are designed as separate switching elements and are usually attached to the transducer material.
  • PCBs based on epoxy resin are often provided, to which fixed-value resistors for the adjustment of the temperature response with a characteristic value (TKK adjustment) are soldered.
  • Thin enamelled copper wires are also used to adjust the temperature response at zero (TKO adjustment).
  • Known flexible printed circuit boards are also used as trimming elements, onto which the trimming resistors can be soldered into the circuits as thin enamelled copper wires or as foil resistors with nickel or copper foil as resistance material.
  • the flexible film can be glued directly onto the sensor body.
  • it is relatively expensive to manufacture the low-impedance trimming resistors with the required accuracy.
  • long wire lengths are usually required, which require a relatively large amount of space on the printed circuit board and which are very labor-intensive when adjusting. Otherwise, film resistors also have relatively poor heat transfer values, so that the compensation effect is flawed.
  • the invention is therefore based on the object of improving a balancing element for transducers of the type mentioned at the outset in such a way that the measurement accuracy of the transducer is increased, and this with minimal adjustment effort.
  • the invention has the advantage that a direct heat transfer to the sensor material is produced by the metallic carrier plate, so that a very precise temperature response compensation can be achieved, which also follows rapid temperature changes.
  • good dissipation of the inherent heat at the compensation resistors is advantageously achieved, so that an additional increase in resistance is avoided.
  • the invention also has the advantage that the matched resistors with their very low resistance values can be produced very precisely and extremely compactly in automated processes by means of the structured thin resistive film, so that no matched resistance differences have to be compensated for, only the slight manufacturing differences of the strain gauges having to be compensated manually .
  • FIG. 1 A schematic representation of a balancing element with connectable bridge circuit
  • 2 the layered structure of a balancing element
  • FIG. 3 an electrical circuit diagram of the balancing element with a transducer bridge circuit.
  • a balancing element 4 for a transducer with bridge circuit 1 is shown schematically, which is designed as a separate component and in which the essential balancing resistors 6, 19, 13, 18 are glued onto a metal carrier plate 20 as structured resistance foil 23.
  • the balancing element 4 essentially orders from a metallic carrier plate 20, which represents a carrier body.
  • This support body 20 must consist of a good heat-conducting material, so that this support plate 20 is preferably made of aluminum.
  • other metallic sheets or plates with good thermal conductivity can also be used.
  • This metallic carrier plate 20 is preferably used with material thicknesses of 0.2 to 1.5 mm.
  • a rectangular base of the carrier plate of approx. 18 x 20 mm has been chosen, since these dimensions are well suited to be attached to standard force transducers and load cells.
  • Support plates 20 of this type can, however, also be produced in other dimensions and shapes, insofar as this is necessary for the respective transducer. Square, round or modified base surface shapes are also conceivable.
  • a layer structure of the adjustment element 4 is shown in FIG. 2, according to which the thickness ratios of the individual layers are shown approximately to scale, but greatly enlarged.
  • the metallic carrier plate 20 is shown as the lower layer, which by far has the greatest layer thickness.
  • On a structured resistance film 23 is glued onto this metallic carrier plate 20, which contains the low-resistance trimming resistors 6, 19, 13, 18 and the conductor tracks 8 with soldering points 5, 7, 11, 12, 15, 16.
  • a homogeneous adhesive layer 22 of approximately 0.005 to 0.025 mm is provided, which at the same time serves as an insulation layer with respect to the carrier plate 20.
  • the overlying resistance foil 23 can consist of nickel, copper or another electrically conductive material with a high temperature coefficient.
  • This resistance film 23 is applied to the carrier plate 20 with a homogeneous thickness of approximately 0.005 to 0.025 mm.
  • This resistance foil 23 is structured with the aid of a photolithographic process, after which the resistors 6, 19, 13, 18, the conductor tracks 8 and the connection points 5, 7, 11, 12, 15, 16 are etched in a manner similar to the known production of strain gauges 2.
  • the conductor tracks 8, connection points 5, 7, 11, 12, 15, 16 and trimming resistors 6, 19, 13, 18 are arranged on the carrier plate 20 in a manner similar to that shown in FIG. 1.
  • the adjustment resistors 6, 19 are provided for the fine adjustment of the temperature response at the zero point and have a resistance value of approximately 0.1 ⁇ and are designed as a rectangular surface of the resistance foil 23 with an edge length of a few mm.
  • resistance values of 0.5 to 1 ⁇ or above may also be required. Since the resistance film 23 is an extremely homogeneous film, such resistance values can be produced with high accuracy without adjustment, so that these resistors 6, 19 do not increase the scatter of the temperature response at the zero point in the initial state.
  • the two trimming resistors 13, 18 for trimming the temperature response at the characteristic value are also designed as structured resistance foils 23 on the carrier plate 20.
  • These temperature-dependent resistors 13, 18th In the present sensor circuit, in which strain gauges 2 of 350 ⁇ are used, in connection with the parallel resistor 10, 17 for optimum linearization of the temperature response for the characteristic value and for an aluminum sensor have a resistance value of approx. 40 ⁇ .
  • This resistor is preferably designed as a measuring grid in order to ensure high accuracy with the smallest dimensions. Since these trimming resistors 13, 18 can be manufactured with a tolerance of ⁇ 0.1% due to the above-described design and due to the selected layer structure, a subsequent individual trimming of the temperature response for the characteristic value (TKK trimming) can be omitted.
  • the grid structure can be used to produce any resistance values that were previously determined by calculation or experiment for the corresponding sensor type.
  • resistance values of approx. 10 to 100 ⁇ may also be necessary for the adjustment resistors 13, 18.
  • the characteristic value (TKK adjustment) is a parallel resistor 10, 17 connected in parallel to the adjustment resistor 13, 18, which is subsequently soldered onto the provided connection points 9, 14.
  • a commercially available fixed resistor in SMD technology with the smallest possible temperature coefficient is provided, which for example has a resistance value of approximately 200 ⁇ .
  • resistance values of 70 to 200 ⁇ can be used. This resistance value of 200 ⁇ is determined for a temperature range from - 10 to + 40 ° C in order to linearize this range.
  • the other trimming resistors 6- r lB r 13- r ia are also provided for such a temperature range.
  • connection soldering points 5 are additionally provided on the left side of the carrier plate 20 for the connection of the strain gauges 2 and on the right in each case two connection soldering points A for the output signals and two connection soldering points E for the brine supply.
  • other connection soldering points 1, 11, 12 can also be arranged on the carrier plate 20, by means of which the electrical connection can be established.
  • the adjustment resistors 13, 18 for the adjustment of the temperature response at the characteristic value are measured and adjusted in a special adjustment method to the previously determined resistance value with high precision. Since these adjustment values can be determined beforehand on the basis of the type of transducer, these adjustment resistors 13, 18 are set to the determined value with high precision even before connection to the strain gauges 2.
  • a protective layer 24 is then applied in order to protect the circuit in those areas which no longer require contacting in the subsequent processes.
  • the lacquer 24 can be a so-called solder stop lacquer, as is usually used in printed circuit board technology and is applied by means of screen printing. Other order processes, such as. B. spraying, brushing, etc. are possible.
  • Fig. 3 of the drawing the electrical circuit diagram of the transducer with the balancing element 4 and the transducer bridge circuit 1 is shown.
  • the two half bridges shown with strain gauges 2 shown in FIG. 1 are connected to form a full bridge.
  • the full bridge can also be formed from a strain gauge quarter bridge or a strain gauge half bridge with additional bridge resistances.
  • the strain gauges 2 have resistance values of z. B. 350 ⁇ and should be used for a temperature range of - 10 to + 4-0 ° C.
  • an adjustment resistor R TKK is connected in series in each case in the feed line 15 for the adjustment of the temperature response at the characteristic value (TKk-adjustmentJ, to which a fixed resistor R- is connected in parallel.
  • the strain sensitivity of the strain gauges (k factor) and the modulus of elasticity of the transducer material are temperature-dependent.
  • Konstantan as a strain gauge strip material with a positive temperature coefficient of the k-factor (TKk> and the negative temperature efficiency of the
  • Elasticity modulus (TKE) of the transducer material both lead to an increase in the force, weight or pressure signal when subjected to mechanical loads, such as when the temperature rises.
  • TKE Elasticity modulus
  • the transducer is used with a reference mass or reference force at different temperatures mechanical stress and from the corresponding Abretewi- derstandswert for the balancing resistors 13, 18 and the par ⁇ allelwiderites 10, determines 17 that is necessary to compensate for this error. Since the trimming resistors R ⁇ cause a relatively strong increase in their resistance value with increasing temperature, an additional voltage drop occurs in the feed lines 15, which is caused by the positive temperature coefficient of the k factor (Tkk) and the negative temperature coefficient of the elasticity module (TKE) counteracts the measurement signal change caused by the sensor material.
  • the values for the trimming resistance and the parallel resistance can be determined on comparison bridges, which can then be transferred to all other sensors of the same type.
  • the adjustment resistances R ⁇ must be produced exactly with the determined resistance values, so that an individual characteristic value adjustment can then be omitted for all subsequent sensor circuits. Due to the selected thickness of the carrier plate 20, no changes in resistance due to warpage or tension in the carrier plate are to be expected in the case of the resistors thereon in the event of temperature changes.
  • the direct bonding 22 with the well thermally conductive carrier plate 20 brings about a rapid temperature compensation both in the event of external temperature effects and in the event of temperature changes which can arise due to self-heating of the resistors on the carrier plate, so that no additional measurement errors can occur as a result.
  • two temperature-dependent adjustment resistors R ⁇ are arranged in the lower bridge branch 25. If necessary, these compensate for unbalances in the manufacture and application of the expansion Measuring strips 2 are provided for TKO fine adjustment.
  • the adjustment unit 4 is connected to the strain gauges 2. Then the zero point of the sensor is measured in a mechanically unloaded state at different temperatures and the resulting TKO is determined. For the adjustment, depending on the sign of the TKO, one of the resistors 6, 19 is changed until the output signal of the bridge 1 is within the specified limits in the entire temperature range.
  • the adjustment is carried out by an "erasing process” in which the resistance layer 22 is reduced by abrasion, so that the resistance value increases. Since these resistance values can only be changed in one direction by "erasing” and since it is not possible to predict which sign the TKO will have, an adjustment resistor 6, 19 is provided in each bridge part in order to be able to carry out an adjustment in both directions.
  • the layer structure chosen ensures that the resistors 6, 19 on the carrier plate 20 have the same temperature and thus the same effect in the event of temperature changes.
  • 8 soldering points are provided in the balancing element 4 in the output conductor tracks, on which a high-resistance of z. B. 1 k ⁇ can be soldered for characteristic value adjustment.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Force In General (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

L'invention concerne un élément d'équilibrage (4) pour un circuit de détection pourvu de jauges de contrainte (2) montées en pont (1). L'élément d'équilibrage (4) selon l'invention est constitué d'une plaque support métallique (20) sur laquelle est collée de manière isolante un film de résistance structuré (24). A partir du film de résistance (23) sont formées, sous forme plane ou de grille, les résistances d'équilibrage à basse impédance (6, 19) ainsi que les résistances d'équilibrage à haute impédance (13, 18) pour la compensation du coefficient de température à zéro (TKO) et pour la compensation du coefficient de température à valeur caractéristique (TKK). L'élément d'équilibrage (4) peut facilement être relié au capteur par l'intermédiaire de la plaque support plane (20), à l'aide d'un plastique approprié et avec une bonne transmission thermique. Sur le capteur achevé, l'élément d'équilibrage est protégé des détériorations mécaniques par une matière de scellement.
EP00906275A 1999-02-08 2000-02-03 Element d'equilibrage pour un capteur Withdrawn EP1151259A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE1999105156 DE19905156A1 (de) 1999-02-08 1999-02-08 Abgleichelement für einen Aufnehmer
DE19905156 1999-02-08
PCT/EP2000/000862 WO2000047965A1 (fr) 1999-02-08 2000-02-03 Element d'equilibrage pour un capteur

Publications (1)

Publication Number Publication Date
EP1151259A1 true EP1151259A1 (fr) 2001-11-07

Family

ID=7896835

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00906275A Withdrawn EP1151259A1 (fr) 1999-02-08 2000-02-03 Element d'equilibrage pour un capteur

Country Status (4)

Country Link
EP (1) EP1151259A1 (fr)
CN (1) CN1157595C (fr)
DE (1) DE19905156A1 (fr)
WO (1) WO2000047965A1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5870699B2 (ja) * 2012-01-10 2016-03-01 ミツミ電機株式会社 センサ出力補正回路及びセンサ出力補正装置、並びにセンサ出力補正方法
DE102015110050A1 (de) * 2015-06-23 2016-12-29 Endress + Hauser Flowtec Ag Feldgerät mit Kompensationsschaltung zur Eliminierung von Umgebungseinflüssen
DE102015214407A1 (de) * 2015-07-29 2017-02-02 Robert Bosch Gmbh Vorrichtung zur Erfassung mindestens einer Eigenschaft eines Mediums und Verfahren zum Abgleich eines Signals der Vorrichtung
CN106370097A (zh) * 2016-08-26 2017-02-01 中航电测仪器股份有限公司 一种用于复合材料的应变计及其制备方法
CN114777970B (zh) * 2022-05-23 2023-04-11 电子科技大学 高刚度测力刀柄上基于柔性电路板的薄膜应变计电桥电路

Family Cites Families (7)

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Publication number Priority date Publication date Assignee Title
DE1490986C3 (de) * 1962-10-01 1974-04-04 Xerox Corp., Rochester, N.Y. (V.St.A.) Verfahren zur Herstellung eines elektrischen Widerstandselements mit teilweiser Entfernung der Widerstandsschicht zwecks Einstellung der Widerstandseigenschaften
US4217785A (en) * 1979-01-08 1980-08-19 Bofors America, Inc. Erasable-foil-resistance compensation of strain gage transducers
DE3113745A1 (de) * 1981-04-04 1982-10-21 Robert Bosch Gmbh, 7000 Stuttgart Duennschicht-dehnungsmessstreifen und verfahren zu seiner herstellung
DE4227764A1 (de) * 1992-08-24 1994-03-03 Schenck Ag Carl Sensor zum Erfassen mechanischer Belastungen
JP2768219B2 (ja) * 1993-06-24 1998-06-25 日本電気株式会社 歪量検出装置並びにその駆動回路及び増幅回路
DE19646441A1 (de) * 1996-11-11 1998-05-14 Heusler Isabellenhuette Elektrischer Widerstand und Verfahren zu seiner Herstellung
DE19753800C2 (de) * 1997-12-04 1999-12-30 Mannesmann Vdo Ag Verfahren zur Herstellung eines elektrischen Widerstandes sowie eines mechanisch-elektrischen Wandlers

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0047965A1 *

Also Published As

Publication number Publication date
CN1157595C (zh) 2004-07-14
WO2000047965A1 (fr) 2000-08-17
DE19905156A1 (de) 2000-08-10
CN1339103A (zh) 2002-03-06

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