US3786883A - Electromagnetically-compensated balance having series connected coils - Google Patents

Electromagnetically-compensated balance having series connected coils Download PDF

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Publication number
US3786883A
US3786883A US00287854A US3786883DA US3786883A US 3786883 A US3786883 A US 3786883A US 00287854 A US00287854 A US 00287854A US 3786883D A US3786883D A US 3786883DA US 3786883 A US3786883 A US 3786883A
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Prior art keywords
load
counter
tare
series
assemblies
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US00287854A
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English (en)
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P Kunz
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Mettler Toledo GmbH Germany
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Mettler Instrumente AG
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Assigned to METTLER-TOLEDO AG (METTLER-TOLEDO SA) (METTLER-TOLEDO LTD), IM LANGACHER GREIFENSEE, SWITZERLAND reassignment METTLER-TOLEDO AG (METTLER-TOLEDO SA) (METTLER-TOLEDO LTD), IM LANGACHER GREIFENSEE, SWITZERLAND CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). NOVEMBER 24, 1989 Assignors: METTLER INSTRUMENTE AG
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G7/00—Weighing apparatus wherein the balancing is effected by magnetic, electromagnetic, or electrostatic action, or by means not provided for in the preceding groups
    • G01G7/02—Weighing apparatus wherein the balancing is effected by magnetic, electromagnetic, or electrostatic action, or by means not provided for in the preceding groups by electromagnetic action
    • G01G7/04—Weighing apparatus wherein the balancing is effected by magnetic, electromagnetic, or electrostatic action, or by means not provided for in the preceding groups by electromagnetic action with means for regulating the current to solenoids
    • G01G7/045—Weighing apparatus wherein the balancing is effected by magnetic, electromagnetic, or electrostatic action, or by means not provided for in the preceding groups by electromagnetic action with means for regulating the current to solenoids having a PID control system

Definitions

  • ABSTRACT An electromagnetically-compensated balance of the type including load and reference compensation coils for returning load and reference assemblies to their neutral positions relative to the balance housing, characterized in that the reference compensation coil is connected in series with reference current regulating means to define a series branch that is connected at one end with one terminal of a direct-current voltage source. Electronic switch means alternately connect the other end of said series branch in series with, and disconnect said other end of said series branch from, said load compensation coil and said voltage source, respectively.
  • the reference current regulating means are operable by a reference control voltage as a function of the displacement of the reference assembly from its neutral position
  • the electronic switch means are operable by a load control voltage to effect series connection between said load and reference compensation coils for time periods that correspond with the displacement of the load assembly from its neutral position.
  • Buffer means are provided for effecting a galvanic coupling between the load and reference coil switching circuits, and stabilizing meanssuch as a dummy load or a catching diode-are provided to; stabilizing the switching operation.
  • This invention relates to load-compensation balances including load and reference assemblies independently suspended from a stationary part of the balance, each of the assemblies being provided with a compensation coil arranged in a common magnetic field.
  • Detector means are provided for generating load and reference control signals the magnitudes of which are a function of the displacement of the load and reference assemblies from their initial neutral positions relative to the housing, respectively, said control signals being operable to regulate the currents flowing in said compensation coils, respectively.
  • Such balances are of the type disclosed in the U.S. patents to Baur No. 3,322,222 and Stroebel No. 3,688,854.
  • both the compensation coil of the reference assembly and also the compensation coil of the load assembly are fed by separate direct currents.
  • the result if determined by the difference between the two currents being related to the current in the reference coil (as determined, for example, by a balanced-bridge network).
  • the reference assembly movement is compensated by a constant direct current, position detector means being provided for detecting the position of the reference assembly to influence by way of correction coils the magnitude of the common magnetic field and thus indirectly the magnitude of the compensation current in the load coil.
  • a primary object of the present invention is to provide an electromagnetically compensated balance including a reference compensation coil connected in series with reference current regulating means to define a series branch, and electronic switch means operable to alternately connect and disconnect this series branch, respectively, in series with a load compensation coil and a direct-current voltage source.
  • the reference current regulating means are operable by a reference control voltage as a function of the displacement of the reference assembly from its normal neutral position
  • the electronic switch means are operable by a load control voltage to effect series connection between said load and reference compensation coils for time periods that correspond with the displacement of the load assembly from its neutral position.
  • a more specific object of the present invention is to provide an electromagnetically compensated balance of the type described above including buffer means arranged between the load and references compensation coils to form a galvanic coupling the amplification ratio of which is preferably lzl
  • This arrangement has the advantage that the analog action control circuit of the reference assembly cannot be influenced by interference pulses from the circuit of the load assembly.
  • a further object of the invention is to provide apparatus of the type described above including means for stabilizing the reference compensation coil circuit during the switching operation.
  • the stabilizing means includes dummy load means to which the reference compensation coil circuit is connected during the periods when it is disconnected from the load compensation coil.
  • the stabilizing means comprises a catching diode that connects the reference compensation coil with ground during the periods the reference compensation coil is disengaged from the load compensation coil.
  • the electronic switch means connects the load coil in series with the reference coil for time periods that correspond with the magnitude of the control voltage developed by the load position detector means, which control voltage is a function of the displacement of the load assembly from the neutral position.
  • the same oscillator means that develops a sawtooth waveform for operating a pulse length modulator that controls the operation of the electronic switch means provides also counting pulses that are supplied to a counter during the time period that the load coil is connected in series with the reference coil.
  • the balance includes counter and indicator means which during the duration of the flow of compensation current in the load coil utilizes high frequency pulses of constant frequency for digital indication or evaluation.
  • This method permits rapid and precise determination of the measuring value, with virtually any degree of resolution.
  • the arrangement is such that only one oscillator is used for supplying the counting pulses and also for controlling the pulse length modulator and the switching means.
  • the requirements made as to the stability of frequency of the oscillator do not have to be high, as fluctuations act in the same manner on the respective predetermined counting time as on the number of counted pulses.
  • the counter is a forward-reverse counter and there is provided a taring means which includes a forward-reverse logic circuit associated with the forward-reverse counter, a tare storage means and a zero detector, and a counter control means for controlling the above mentioned components, and a tare switch.
  • FIG. 1 is a diagrammatic cross-sectional view a first embodiment of the electromagnetically compensated balance of the present invention, the electrical circuit being illustrated in block diagram form;
  • FIG. 2 is a voltage versus time diagram illustrating the operation of the pulse length modulator
  • FIG. 3 is a detailed schematic diagram of the buffer means of FIG. 1;
  • FIG. 4 is an electrical schematic diagram of a second embodiment of the invention.
  • the balance comprises a stationary portion 1 including a housing 2 which is made of magnetic material and is closed on all sides, and a permanent magnet 3 arranged centrally in the housing 2.
  • the housing 2 is secured by means of an annular flange 4 to a cantilever bracket 5 which in turn is fixedly connected with a column 6 that is carried by a fixed support.
  • the middle portion 7 of the permanent magnet 3 forms an annular air gap 9.
  • the annular load coil 10 which is a component of a load assembly 12 of the balance
  • the annular reference coil 11 which is a component of a reference assembly 13.
  • the load assembly 12 and the reference assembly 13 are each connected with the column 6, and thus guided parallel to each other, by two pairs of resilient suspension means 14 and 14' and 15 and 15', respectively.
  • a plurality of apertures 16 and 16 in the upper and lower end portions respectively of the housing 2 permit free vertical movement of the load assembly 12 and the reference assembly 13.
  • a balance pan 17 is arranged above the suspension means 14 of the load assembly 12, and secured thereto, for carrying the material to be weighed.
  • capacitors 18 and 18', 19 and 19' Arranged concentrically in pairs above and below the air gap 9 and symmetrically relative thereto, are four stationary annular capacitors 18 and 18', 19 and 19', respectively.
  • the capacitors l8 and 18 act as position detectors in respect of the reference assembly 13.
  • the negative terminal of the direct-current voltage source S is connected with the input terminal of change-over switch means 23 via current regulator means 21, reference compensation coil 11 and buffer means 22 (which includes at least one field effect transistor), thereby defining a first series branch.
  • the switch means 23 alternately connects this series branch with the positive terminal of the source via dummy load 24 and the load compensation coil 10, respectively.
  • the reference assembly 13 is returned to the neutral position.
  • the compensation current is passed by way of buffer means 22 to an electronic switch means 23 from which it can flow alternately to the load coil 10 or to a dummy load 24.
  • the buffer means 22 has a low input impedance and a high output impedance. It has an amplification ratio of 1:1 and forms a galvanic coupling between the switching circuits of the load assembly 12 and the reference assembly 13. This arrangement has the advantage that the analog action control circuit of the reference assembly cannot be influenced by interference pulses from the circuit of the load assembly.
  • the compensation current in the load coil 10 is controlled as follows. Upon deflection of the load assembly 12 out of the neutral position, for example under the weight of the material to be weighed, the two capacitors l8 and 18' produce a difference signal which is converted by difference signal generating means 25 and passed to current regulating means 26. The control voltage produced therein is applied to a pulse length modulator 27 which in turn is controlled by a quartz oscillator 28 having a frequency divider 29 connected downstream thereof. As shown in FIG. 2, in the pulse length modulator 27, a sawtooth voltage is continuously compared with the control voltage from the regulator 26.
  • One output of the pulse length modulator 27 leads to a switch control means in the form of a flip-flop 30 which, in conjunction with the second input from the oscillator 28, controls the switching times of the switch means 23, to provide a flow of current to the load coil 10 or to the dummy load 24.
  • the operation of the pulse length modulator 27 for varying the lengths of the pulses in accordance with the magnitude of the control voltage Vc (FIG. 2) is disclosed in greater detail in the copending Kunz application Ser. No. 222,960 filed Feb. 2, 1972 and the Naydan et al U.S. Pat. No. 3,028,550.
  • the weight, which is constant, of the reference assembly 13 is 200 g., while that of the load assembly 12 (without material to be weighed) is 400 g.
  • the weighing range selected is l,200 g., with an excess range (reserve) of 400 g.; the total possible weight which can be compensated of the load assembly is therefore 2,000 g.
  • the ratio of the coil windings is selected as l:l0, corresponding to the ration of the weight of the reference assembly l3 and the total possible weight of the load assembly 12, therefore the same rated current results in both coils at maximum load.
  • the frequency of the oscillator 28 is 10 MHz.
  • the full value which serves as a counting frequency, acts on the flip-flop 30 and also a gate 31 and an auxiliary logic means forming a counter control means 32.
  • the divider 29 reduces the oscillator frequency in the ratio 1120,000; pulse length modulator 27 connected downstream of the divider 29 therefore receives a pulse every 2 ms, which pulse returns the sawtooth voltage to zero and allows it to rise again, and after transmission by way of the flip-flop 30, switches the switch means 23 to pass the compensation current to the load coil 10.
  • the gate 31 is opened and counting pulses from the oscillator 28 are allowed to pass to act on a counter 33.
  • a second divider 34 which again reduces the frequency, this time in the ratio 1:100, and thus delivers a pulse to the counter control means 32 every 0.2 s, which pulse causes the condition of the counter 33 to be transmitted to an indication storage means 35 from which it passes to an indicator 36 (and at the same time to a binary coded decimal output 37). After the condition of the counter 33 has been transmitted, the counter 33 is set to zero.
  • the details of the counter and indicator means including the counter control means 32 are set forth in the copending Allenspach US. application Ser. No. 244,054 filed Apr. 14, 1972, and assigned to the assignee of the instant application.
  • tare storage means 38 there is connected in parallel with the indication storage means 35 a tare storage means 38, while there is also provided a forward-reverse logic circuit 39, a manually operable tare switch 40 which is connected to the counter control means 32, and a zero detector 41.
  • tare switch 40 When weighing with tare, after the tare switch 40 is actuated the value resulting from the tare weighing operation is also accommodated in the tare storage means 38. In subsequent weighing operations, the value of the tare storage means 38 is introduced into the counter 33 at the beginning of each weighing operation.
  • the forward reverse logic circuit 39 causes the counter 33 to count backwards, that is to say, the counting pulses entering therein are subtracted from the tare weight until the zero detector 41 signals that zero has been reached. This signal passes to the forward-reverse logic circuit 39 which then causes the counter 33 again to count in the forward direction.
  • the number of pulses passing into the counter 33 is equal to the number of pulses stored in the tare storage means 38; at the end of the measuring cycle of 0.2 s, the counter 33 has therefore reached zero, and this result is stored in the indication storage means 35 and is indicated at the indicator 36 and the binary coded decimal output 37.
  • the number of counting pulses passing into the counter 33 is greater (or lower respectively) than the number of pulses stored in the tare storage means 38.
  • the excess (or deficit respectively) is indicated in the indication storage means 35 at the end of the measuring cycle and for the duration of the next measuring cycle.
  • the dead load of the balance can also be taken into account, in the above described manner.
  • the dead load is eliminated from the indication.
  • the weight of the reference assembly 13 is compensated with direct current which flows continuously through the coil 11 while the weight of the load assembly 12 is compensated with direct current which flows through the coil 10 only intermittently, in the form of pulses of relatively short duration (less than 2ms), the amplitude of the two currents being identical.
  • the overall arrangement is a real mass comparison device of high precision and with direct digital indication of high resolution, but which does not require highly stable reference voltage sources or other expensive components such as digital voltmeters.
  • the frequency of the oscillator 28 also does not have to be particularly stable, as fluctuations act in the same manner both on the length of the compensation current pulses supplied to the load coil 10 and on the measuring time.
  • the electronic switch means 23' (which is illustrated schematically in the form of a single pole switch) merely connects and disconnects from the load compensation coil 10 the series branch including reference current regulator means 21', reference compensation coil 11, and buffer means 22.
  • the connection between buffer means 22' and switch means 23' is connected with ground via catching diode D, whereby a lower leakage power is achieved.
  • An electromagnetically-compensated balance including, in combination, a stationary housing (2); load (12) and reference (13) assemblies connected for independent movement relative to said housing, said assemblies normally having no-load neutral positions relative to said housing; load and reference (11) compensation coils connected with said load and reference assemblies, respectively; means (3) establishing a magnetic field common to said load and reference compensation coils; and means for energizing said load and reference compensation coils when the assemblies associated therewith are displaced from their neutral positions in such a manner relative to said magnetic field as to return said assemblies to their neutral positions, respectively, said energizing means comprising a. a direct-current voltage source (S) having a first terminal connected with one end of the load compensation coil;
  • S direct-current voltage source
  • a reference current regulator (21) connected in series with the reference compensation coil to define a series branch one end of which is connected with the other terminal of said voltage source;
  • switch means alternately operable between first and second conditions for connecting and disconnecting the other end of said series branch with the other end of said load compensation coil, respectively;
  • reference position detector means being connected with said reference current regulator means to regulate the current in said series branch as a function of the magnitude of the reference control voltage
  • load position detector means (18, 18', 25) for generating a load control voltage that corresponds with the displacement of the load assembly from its neutral position
  • said buffer means includes at least one field effect transistor.
  • said stabilizing means comprises a dummy load (24) connected at one end with said first terminal of said voltage source, said switch means being operable in said second condition to connect the other end of said dummy load with said series branch.
  • said stabilizing means comprises catching diode means (d) connected at one end between said series branch and said switch means, the other end of said catching diode means being connected with ground.
  • said means for controlling the operation of said switch means comprises sawtooth waveform generator means including an oscillator (28), and pulse length modulator means (27) for comparing said sawtooth waveform and said load control voltages to produce switch control voltage pulses the lengths of which are a function of said load control voltage.
  • Apparatus as defined in claim 8 and further including counter means (33) for counting pulses produced by said oscillator means during the time periods of said switch means is in said first condition, and indicator means (36) for indicating as a function of the total count of said counter means the load applied to said load assembly.
  • said counter means further includes a forward-reverse counter (33), and taring means for initially subtracting from said counter means counting pulses corresponding with the tare value of the balance, said taring means including tare store means (38) for storing the tare count, forward-reverse logic means (39) connected with said counter means, zero detector means (41) connected between said tare store means and said forward-reverse logic means for reversing the direction of said counter means when the count stored in said tare storage means equals zero, and counter control means (32) for introducing the initial tare count into said tare storage means and for controlling the operation of said forward-reverse logic means, said counter means, and said tare storage means.
  • taring means including tare store means (38) for storing the tare count, forward-reverse logic means (39) connected with said counter means, zero detector means (41) connected between said tare store means and said forward-reverse logic means for reversing the direction of said counter means when the count stored in said tare storage means

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • General Physics & Mathematics (AREA)
  • Control Of Stepping Motors (AREA)
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  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
US00287854A 1971-09-22 1972-09-11 Electromagnetically-compensated balance having series connected coils Expired - Lifetime US3786883A (en)

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JP (1) JPS5149428B2 (de)
CH (1) CH529999A (de)
DE (1) DE2233850B2 (de)
FR (1) FR2153235B1 (de)
NL (1) NL7210824A (de)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3860077A (en) * 1973-03-06 1975-01-14 Mettler Instrumente Ag Electrical balance with taring means
US3890833A (en) * 1972-08-18 1975-06-24 Precisa Ag Pressure measuring apparatus
FR2321118A1 (fr) * 1975-08-11 1977-03-11 Sartorius Werke Gmbh Dispositif dynamometrique ou de pesage sans fleau a compensation electromagnetique
US4062416A (en) * 1975-04-23 1977-12-13 Sartorius-Werke Gmbh Electromagnetically compensating beamless dynamometer or weighing machine
US4099587A (en) * 1975-11-18 1978-07-11 Mettler Instrumente, Ag Electromagnetic compensation weighing apparatus including preloading and load-responsive current components
US4156361A (en) * 1976-01-14 1979-05-29 Sartorius-Werke Gmbh Calibratable electromagnetically compensating balance
US4189017A (en) * 1977-09-20 1980-02-19 Mettler Instrumente Ag Weighing apparatus including digitalization error correcting means
US4236590A (en) * 1978-01-27 1980-12-02 Sartorius Gmbh Balance with compensated loading and reference systems
FR2494434A1 (fr) * 1980-11-19 1982-05-21 Sartorius Gmbh Balance electrique comportant un poids ou levier de calibrage
US4354563A (en) * 1980-06-06 1982-10-19 Mettler Instrumente Ag Electromagnetic weighing apparatus having multiple air gaps
US4373596A (en) * 1980-08-22 1983-02-15 Peter Kunz Weighing apparatus with electromagnetic force compensation
US4494022A (en) * 1983-06-10 1985-01-15 Shimadzu Corporation Electromagnetic force-transducer
US4614245A (en) * 1982-10-05 1986-09-30 Yamato Scale Company, Limited Device for measuring force
US4627505A (en) * 1984-06-29 1986-12-09 Mettler Instrumente Ag Weighing apparatus and method for automatically monitoring a constant current source
US4676329A (en) * 1985-10-18 1987-06-30 Arthur Reichmuth Weighing apparatus including auxiliary tare store means
US5184690A (en) * 1990-02-28 1993-02-09 Shimadzu Corporation Electronic balance
US20070075810A1 (en) * 2005-09-30 2007-04-05 Shimadzu Corporation Electromagnetic-force-balancing-type electronic balance
US20080053249A1 (en) * 2006-09-05 2008-03-06 Mettler-Toledo Ag Force-measuring device and reference unit
DE102016009098A1 (de) 2016-07-27 2018-02-01 Fresenius Medical Care Deutschland Gmbh Vorrichtung und Verfahren zur Prüfung eines Wägesystems eines Blutbehandlungsgerätes
RU2782678C1 (ru) * 2021-12-20 2022-10-31 Федеральное государственное казённое военное образовательное учреждение высшего образования "Военная академия материально-технического обеспечения имени генерала армии А.В. Хрулева" Министерства обороны Российской Федерации Устройство для возбуждения непрерывных колебаний струны импульсом полусинусоидальной формы

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2658628C3 (de) * 1976-12-23 1982-01-07 Sartorius GmbH, 3400 Göttingen Elektromagnetisch kompensierende Kraftmeß- oder Wägevorrichtung
JPS5396136U (de) * 1977-01-07 1978-08-04
CH623133A5 (de) * 1977-12-06 1981-05-15 Mettler Instrumente Ag
JPS56143920A (en) * 1980-04-11 1981-11-10 Nippon Kontoroola- Seisakusho:Kk Automatic balance type weight detector

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US3133606A (en) * 1961-06-28 1964-05-19 Farrington Machines Inc Scales
US3172493A (en) * 1961-07-17 1965-03-09 Oskar Glemser Apparatus for the continuous measurement of variations in the weight of a substance
US3186504A (en) * 1961-09-08 1965-06-01 Philips Corp Weighing apparatus
US3295368A (en) * 1964-07-13 1967-01-03 W C Dillon & Company Inc Electrical load cell
US3322222A (en) * 1964-11-12 1967-05-30 Baur Fritz Compensated electromagnetic balance
US3688854A (en) * 1971-03-01 1972-09-05 Mettler Instrumente Ag Balance with electromagnetic compensation

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3133606A (en) * 1961-06-28 1964-05-19 Farrington Machines Inc Scales
US3172493A (en) * 1961-07-17 1965-03-09 Oskar Glemser Apparatus for the continuous measurement of variations in the weight of a substance
US3186504A (en) * 1961-09-08 1965-06-01 Philips Corp Weighing apparatus
US3295368A (en) * 1964-07-13 1967-01-03 W C Dillon & Company Inc Electrical load cell
US3322222A (en) * 1964-11-12 1967-05-30 Baur Fritz Compensated electromagnetic balance
US3688854A (en) * 1971-03-01 1972-09-05 Mettler Instrumente Ag Balance with electromagnetic compensation

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3890833A (en) * 1972-08-18 1975-06-24 Precisa Ag Pressure measuring apparatus
US3860077A (en) * 1973-03-06 1975-01-14 Mettler Instrumente Ag Electrical balance with taring means
US4062416A (en) * 1975-04-23 1977-12-13 Sartorius-Werke Gmbh Electromagnetically compensating beamless dynamometer or weighing machine
FR2321118A1 (fr) * 1975-08-11 1977-03-11 Sartorius Werke Gmbh Dispositif dynamometrique ou de pesage sans fleau a compensation electromagnetique
US4099587A (en) * 1975-11-18 1978-07-11 Mettler Instrumente, Ag Electromagnetic compensation weighing apparatus including preloading and load-responsive current components
US4156361A (en) * 1976-01-14 1979-05-29 Sartorius-Werke Gmbh Calibratable electromagnetically compensating balance
US4189017A (en) * 1977-09-20 1980-02-19 Mettler Instrumente Ag Weighing apparatus including digitalization error correcting means
US4236590A (en) * 1978-01-27 1980-12-02 Sartorius Gmbh Balance with compensated loading and reference systems
US4354563A (en) * 1980-06-06 1982-10-19 Mettler Instrumente Ag Electromagnetic weighing apparatus having multiple air gaps
US4373596A (en) * 1980-08-22 1983-02-15 Peter Kunz Weighing apparatus with electromagnetic force compensation
FR2494434A1 (fr) * 1980-11-19 1982-05-21 Sartorius Gmbh Balance electrique comportant un poids ou levier de calibrage
US4614245A (en) * 1982-10-05 1986-09-30 Yamato Scale Company, Limited Device for measuring force
US4494022A (en) * 1983-06-10 1985-01-15 Shimadzu Corporation Electromagnetic force-transducer
US4627505A (en) * 1984-06-29 1986-12-09 Mettler Instrumente Ag Weighing apparatus and method for automatically monitoring a constant current source
US4676329A (en) * 1985-10-18 1987-06-30 Arthur Reichmuth Weighing apparatus including auxiliary tare store means
US5184690A (en) * 1990-02-28 1993-02-09 Shimadzu Corporation Electronic balance
US7365275B2 (en) * 2005-09-30 2008-04-29 Shimadzu Corporation Electromagnetic-force-balancing-type electronic balance
US20070075810A1 (en) * 2005-09-30 2007-04-05 Shimadzu Corporation Electromagnetic-force-balancing-type electronic balance
US20080053249A1 (en) * 2006-09-05 2008-03-06 Mettler-Toledo Ag Force-measuring device and reference unit
US7690273B2 (en) * 2006-09-05 2010-04-06 Mettler-Toledo Ag Force-measuring device and reference unit
CN101140182B (zh) * 2006-09-05 2013-10-16 梅特勒-托利多公开股份有限公司 测力装置和基准单元
DE102016009098A1 (de) 2016-07-27 2018-02-01 Fresenius Medical Care Deutschland Gmbh Vorrichtung und Verfahren zur Prüfung eines Wägesystems eines Blutbehandlungsgerätes
WO2018019423A1 (de) 2016-07-27 2018-02-01 Fresenius Medical Care Deutschland Gmbh Vorrichtung und verfahren zur prüfung eines wägesystems eines blutbehandlungsgerätes
DE102016009098B4 (de) 2016-07-27 2018-06-14 Fresenius Medical Care Deutschland Gmbh Vorrichtung und Verfahren zur Prüfung eines Wägesystems eines Blutbehandlungsgerätes
RU2782678C1 (ru) * 2021-12-20 2022-10-31 Федеральное государственное казённое военное образовательное учреждение высшего образования "Военная академия материально-технического обеспечения имени генерала армии А.В. Хрулева" Министерства обороны Российской Федерации Устройство для возбуждения непрерывных колебаний струны импульсом полусинусоидальной формы

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Publication number Publication date
FR2153235B1 (de) 1976-10-29
DE2233850A1 (de) 1973-04-05
CH529999A (de) 1972-10-31
FR2153235A1 (de) 1973-05-04
DE2233850B2 (de) 1974-02-28
JPS4841767A (de) 1973-06-18
NL7210824A (de) 1973-03-26
JPS5149428B2 (de) 1976-12-27

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