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
  • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
  • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
  • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
  • G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
  • G01D5/2006—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils
  • G01D5/202—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils by movable a non-ferromagnetic conductive element
• • 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
  • 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
  • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
  • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
  • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
  • G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
  • G01D5/2006—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils
  • G01D5/2013—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils by a movable ferromagnetic element, e.g. a core

Definitions

• the invention relates to a circuit for measuring distances, with at least two inputs, at least one measuring coil and with at least one signal source, at least two input signals being able to be generated by means of the signal source, the inputs being controllable by means of the input signals and the input signals being preferably preprocessed, contact the inputs of the measuring coil.
• the invention further relates to a method for measuring distances, in particular for operating a circuit for measuring distances, with at least two inputs, at least one measuring coil and with at least one signal source, wherein at least two input signals are generated by means of the signal source, the inputs using the Input signals are controlled and the input signals, preferably preprocessed, are applied to the inputs of the measuring coil,
• - measuring operation the circuit is controlled with two antiphase alternating voltages.
• a DC offset voltage signal - DC voltage component - is superimposed on the AC voltages. Since the current fed to both circuits The ends of the measuring coil must be the same, different voltages are established via the resistors assigned to the measuring coil, which are also assigned to an operational amplifier circuit, which are caused by the offset of the AC voltages and the measuring coil as well as the temperature-dependent components.
• the temperature-dependent output voltage - DC voltage - is determined with another operational amplifier.
• the overall transfer function is thus a low-pass function, which is smoothed by a further capacitance.
• the low pass results from the difference between a high pass and an amplification path matched with it.
• the temperature can be determined and temperature-related measurement errors can be corrected. However, these measurements are seldom inserted into the normal measurements with the purely AC input signals. During the measurement with purely alternating voltage input signals, a direct voltage component can also be determined, which is used to record and correct the temperature drift of the measuring coil.
• the known circuit is particularly problematic in that the occurring time constants of the filtering are very large and the known circuit is relatively large due to its structure and is therefore not suitable for use in which there is only a very small space for the circuit.
• the present invention is therefore based on the object of specifying a circuit and a method for measuring distances of the type mentioned at the outset, by means of which the circuit can be used even in a small space available for the circuit.
• the above object is achieved by a circuit for measuring distances with the features of claim 1.
• the circuit in question is then designed and developed in such a way that the input signals are applied to at least one preferably clocked SC network and are used to generate a measurement signal and / or an output signal which is dependent on the influence of temperature.
• a method for measuring distances of the type mentioned at the outset is designed such that the input signals are present at at least one preferably clocked SC network and are used to generate a measurement signal and / or an output signal which is dependent on the influence of temperature.
• the high-pass circuit is replaced by an equivalent passive double-resistive reference network, which has a voltage divider and an inductor comprises, which is connected in parallel to one of the resistors of the voltage divider.
• the transfer function of this filter is that of a high-pass first degree
• a known wave flow diagram can now be created using known methods.
• a three-port parallel adapter is used to adapt the different wave resistances of the three components of the reference network to each other.
• the wave flow diagram of a resistive voltage source is located on the left side of the three-port parallel adapter, the wave flow diagram of the inductance in the top center and the wave flow diagram of the terminating resistor on the right side. Since wave filters are time-discrete, a new frequency variable ⁇ is used instead of the complex frequency variable p
• T 1 / F is the sampling period and F is the sampling frequency.
• F the sampling frequency
• the adapter equations can be set up as follows:
• the signal can be inverted in the wave flow diagram of the inductance.
• At least two input signals could be essentially unipolar and / or in opposite phases.
• the input signals are preferably essentially square-wave voltages, since then input signals in phase opposition can be generated particularly easily.
• the input signals could be proportional by means of at least one filter and / or filterable by means of a high pass.
• the SC network could have at least one SC amplifier. This would allow a particularly simple construction of the circuit.
• a first SC amplifier could be implemented as a positive delayed SC amplifier and / or multiply two inputs by one factor each. If the SC amplifier is implemented as a positive delayed SC amplifier, parasitic currents could be reduced in this way.
• a second SC amplifier could be implemented as a positive delayed SC amplifier and / or at least one of the input signals, preferably not amplified, could be delayed by a half period of the clock frequency.
• the SC network could have at least one SC integrator.
• the SC integrator could be implemented as a negative, non-delayed SC integrator and / or have a gain of one and / or be lossy.
• the output of the SC integrator could be applied in a particularly simple manner to a second input of the first SC amplifier.
• the outputs of the first SC amplifier and the second SC amplifier could be addable by means of an SC adder.
• a temperature-dependent output signal that could be used to compensate for the temperature influence could thus be tapped at the output of the SC adder.
• the output of the first SC amplifier could be applied to the inputs of the SC integrator and / or the SC adder. Additionally or alternatively, the output of the second SC amplifier could be present at a second input of the SC adder.
• the SC network could also have at least one SC amplifier and / or at least one SC integrator and / or at least one SC adder.
• the first and / or the second SC amplifier and / or the SC adder could not be implemented with a delay.
• the SC integrator could be implemented with a positive delay. The output signal could thus be inverted.
• the SC network could have at least one SC amplifier and / or at least one SC integrator and / or at least one SC differential amplifier.
• At least one of the input signals could be storable in the SC integrator.
• Another factor could be a capacity of the SC integrator can be deleted from the result in each clock period.
• An SC amplifier could advantageously be implemented as a positive delayed SC amplifier and / or at least one of the input signals not amplified and / or delayed by a half period of the clock frequency.
• the output of the SC amplifier and the SC integrator could be subtractable by means of an SC differential amplifier and / or delayed by a half period of the clock frequency.
• the output of the SC amplifier could be applied to the second input of the SC integrator in a particularly simple manner.
• the output signal could thus have a delay of one clock period.
• the method according to the invention could serve in particular to operate a circuit according to the above statements.
• a circuit operated by means of this method is particularly easy to integrate due to its good matching behavior.
• Fig. 1 in a schematic representation, a known circuit for
• Fig. 4 in a schematic representation, a wave flow diagram of the
• FIG. 5 in a schematic representation, an SC implementation of a
• FIG. 9 in a schematic representation, a further embodiment of a circuit according to the invention.
• Fig. 10 shows the transfer function of the circuit shown in Fig. 9.
• the known circuit for measuring distances is designed as a discrete circuit and has two inputs 1, 2 and a measuring coil 3.
• Two input signals e pos and e n8g can be generated by means of a signal source (not shown here).
• the inputs 1, 2 are controlled by means of the input signals e pos and e neg , the input signals e pos and e n ⁇ g being preprocessed at the inputs 1, 2 of the measuring coil 3.
• the known AC-excited circuit enables the measurement of a DC voltage component that is proportional to the temperature.
• the operational amplifiers following inputs 1, 2 form a voltage / current converter with their resistors.
• the current is coupled into the measuring coil 3 from both sides.
• the AC input signals e pos and e n8g shown in FIG. 2a are used to control the inputs.
• the input signals e pos and e n ⁇ g shown in FIG. 2b are used to determine the linearly dependent temperature behavior of the circuit and the measuring coil 3.
• the operational amplifier 5 assigned to the input 1 has a low-pass behavior in connection with the resistors R 2 , R 3 and the capacitance C 2
• the operational amplifier 6 assigned to the input 2 in connection with the resistors R. ,, R 3 and the capacities C, and C 2 has a bandpass behavior.
• the overall transfer function is a low-pass function for ideally on, which is smoothed by the capacitance C 2 .
• the low pass results from the difference between a high pass and an amplification path matched with it.
• the temperature can be determined and temperature-related effects can be corrected.
• FIG. 3 shows an equivalent passive double-resistive reference network of a high-pass circuit. It consists of a voltage source e, a voltage divider of the resistors R., and R 2 and an inductor L connected in parallel with the resistor R 2.
• the transfer function of this filter is that of a first-order high-pass filter
• the wave flow diagram comprises a three-port parallel adapter 7 in which the different wave resistances of the three components of FIG. 3 are matched to one another.
• the wave flow diagram of the resistive voltage source e is located on the left-hand side, the wave flow diagram of the inductance L in the top center and the terminating resistor R 2 on the right-hand side. Since wave filters are time-discrete, a new frequency variable ⁇ must be used instead of the complex frequency variable p
• T 1 / F is the sampling period and F is the sampling frequency.
• F the sampling frequency
• the adapter equations to be calculated can be set up as follows:
• the signal can be inverted in the wave flow diagram of the inductance.
• FIG. 5 shows an SC implementation of the high-pass circuit according to the invention.
• the circuit here has an SC network, an SC amplifier 8 being used to simulate equation 13.
• the input signal e pos and the input signal b 2 * of the SC amplifier 8 are delayed positively and multiplied by the coefficients ⁇ - and ⁇ 2 in accordance with equation 13.
• the output of the SC amplifier 8 is also the output of the high-pass circuit.
• Equation 13 is simulated as capacitance relationships in the signal paths. Equation 13 and equation 15 are implemented by a non-delayed negative SC integrator 9. By coupling the output signal of the SC integrator 9 into the SC amplifier 8 in phase ⁇ , the feedback loop is closed. The transfer function of this high pass circuit is shown in Fig. 6. The time-discrete high-pass function of the high-pass circuit is clearly recognizable here.
• FIG. 7 A circuit according to the invention for measuring distances is shown in FIG. 7.
• the circuit comprises two inputs 1, 2, a signal source (not shown here) and a measuring coil (also not shown).
• the inputs 1, 2 are controlled by means of two input signals e pos and e n ⁇ g generated by the signal source.
• the input signals e pos and e n ⁇ g are applied to a clocked SC network and are used to generate a measurement signal and / or an output signal U which is dependent on the influence of temperature.
• Part of the circuit corresponds to the high-pass circuit of FIG. 5.
• the circuit also has an SC amplifier 10, the input signal e neg being present at the output of the operational amplifier of the SC amplifier 10 at the same time as the SC amplifier 8 the output signal supplies at the operational amplifier.
• the timing of the SC amplifier 10 is also with the Clocking of the upper SC amplifier 8 identical.
• the input signal e n ⁇ g is shifted to the output with a positive delay of half a clock period.
• the SC network has an SC adder 11, which serves to add the two input signals, ie the output signals of the SC amplifiers 8 and 10.
• the SC network is a positive delayed SC circuit, which has a total delay of one clock period. If this is too high, the input amplifiers and the output amplifier could also not be implemented with a delay. The SC integrator must then be implemented with a positive delay. In this case the output signal is inverted.
• FIG. 8 shows the transfer function of the circuit of FIG. 9. It can be clearly seen that the SC network has a low-pass behavior and is therefore very well suited for DC voltage measurement.
• b 2 * can be derived as follows:
• the output voltage of the high pass is the voltage across the resistor R 2 or the voltage across the inductor L, since both elements are connected in parallel.
• the voltage of the inductance is defined by
• the output voltage is therefore the difference between the incident wave a 2 and the negative reflected wave b 2 divided by 2. Without the division, a maximum level of OdB is again obtained, which is why the signal can again be added to the input signal e neg .
• a circuit that realizes this is shown in FIG. 9.
• the circuit comprises a positive delayed SC amplifier 12, a lossy SC integrator 13 and an SC differential amplifier 14.
• the factor (1- ⁇ 2 ) can be seen in FIG. 9 by the lossy SC integrator 13 realize.
• ⁇ 2 is less than 1
• the integrator capacitance of size (1- ⁇ 2 ) C is used and a capacitance of size ⁇ 2 C is connected in parallel, which is periodically discharged.
• ⁇ 2 is always less than 1. Since the output value at the SC integrator 13 should always be positive, the input signal e pos positive delayed by ⁇ multiplied. The output voltage of the high pass is generated by means of the SC differential amplifier 14. The difference a 2 -b 2 * is generated with the input capacitance for the lossy integrator 13. For this purpose, the SC differential amplifier 14 is initialized with ⁇ and the output signal U is thus inverted. As already described with reference to FIG. 7, the second input signal e n8g is applied to the SC amplifier 12 and passed on to the SC differential amplifier 14.
• the transfer function of the circuit shown in FIG. 9 is shown in FIG. 10. It can be seen that apart from a phase rotation of 180 °, no change compared to the transfer function in FIG. 8 can be observed. Due to the good matching properties of the circuits, the measured DC voltage output signal U is very well suited for a temperature correction.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Transmission And Conversion Of Sensor Element Output (AREA)
• Amplifiers (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Related Child Applications (1)

Publications (1)

Family

ID=7699625

Family Applications (1)

Country Status (5)

Families Citing this family (33)

Citations (1)

Family Cites Families (11)

• 2002
  • 2002-09-19 JP JP2003531122A patent/JP2005504286A/ja active Pending
  • 2002-09-19 WO PCT/DE2002/003507 patent/WO2003027613A1/de not_active Ceased
  • 2002-09-19 DE DE10243631A patent/DE10243631A1/de not_active Ceased
  • 2002-09-19 DE DE50214778T patent/DE50214778D1/de not_active Expired - Lifetime
  • 2002-09-19 EP EP02774385A patent/EP1427996B1/de not_active Expired - Lifetime
• 2004
  • 2004-03-18 US US10/803,298 patent/US7061230B2/en not_active Expired - Fee Related
• 2008
  • 2008-06-09 JP JP2008150873A patent/JP4796605B2/ja not_active Expired - Fee Related

Patent Citations (1)

Also Published As

Similar Documents

Legal Events