EP0231980B1 - Méthode pour la transmission de signaux de mesure d'au moins deux transducteurs par liaison à transmission optique - Google Patents

Méthode pour la transmission de signaux de mesure d'au moins deux transducteurs par liaison à transmission optique Download PDF

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Publication number
EP0231980B1
EP0231980B1 EP87200161A EP87200161A EP0231980B1 EP 0231980 B1 EP0231980 B1 EP 0231980B1 EP 87200161 A EP87200161 A EP 87200161A EP 87200161 A EP87200161 A EP 87200161A EP 0231980 B1 EP0231980 B1 EP 0231980B1
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EP
European Patent Office
Prior art keywords
pulses
time
signal
optical
pulse
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
EP87200161A
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German (de)
English (en)
Other versions
EP0231980A2 (fr
EP0231980A3 (en
Inventor
Jürgen Dipl.-Ing. Kordts
Reiner Uwe Dr. Orlowski
Ingobert Heinrich Gorlt
Gerhard Dr. Martens
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.)
Envec Mess und Regeltechnik GmbH and Co
Original Assignee
Envec Mess und Regeltechnik GmbH and Co
Philips Patentverwaltung GmbH
Philips Gloeilampenfabrieken NV
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.)
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Publication of EP0231980A2 publication Critical patent/EP0231980A2/fr
Publication of EP0231980A3 publication Critical patent/EP0231980A3/de
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Publication of EP0231980B1 publication Critical patent/EP0231980B1/fr
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
    • G08C19/00—Electric signal transmission systems
    • G08C19/16—Electric signal transmission systems in which transmission is by pulses
    • G08C19/24—Electric signal transmission systems in which transmission is by pulses using time shift of pulses
    • G—PHYSICS
    • G08—SIGNALLING
    • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
    • G08C23/00—Non-electrical signal transmission systems, e.g. optical systems
    • G08C23/06—Non-electrical signal transmission systems, e.g. optical systems through light guides, e.g. optical fibres

Definitions

  • the invention relates to a method for transmitting at least two measured values by means of light pulses directed from an optical transmitter over an optical transmission path to an optical receiver, the time interval between which is evaluated as a measure of the measured value.
  • a method of this type is known from EP-A1 00 75 701.
  • Optical transmission links and in particular optical fibers (LWL) are insensitive to electromagnetic interference. They are suitable for use in potentially explosive environments and enable measured values to be transmitted over long distances.
  • Energy from a voltage source is required for the electronic processing of the measured values and for the formation of the optical transmission pulses.
  • the required voltage is generated by photo elements, to which light output is supplied via an optical line.
  • batteries could also be provided in the measuring device. In any case, it is desirable to keep the energy consumption of the measuring device low.
  • the invention is therefore based on the object of designing the method of the type mentioned at the outset in such a way that the energy consumption for the optical transmission of the measured values is reduced.
  • the solution is achieved in that the measured values are transmitted directly in cyclical succession in always the same order, that an optical measurement pulse is transmitted for each measured value, the time interval from which an optical measurement pulse assigned to a previous measured value forms a measure of the size of the measured value, and that for each Cycle of measured values an optical identification pulse is transmitted, the time interval from a previous optical measurement pulse is smaller than the minimum possible time interval between two successive optical measurement pulses.
  • the invention is based on the knowledge that the majority of the energy required is used to form the optical signals. It was recognized that considerably less energy is required for the pulsed transmission which is already considered as an alternative in the known case than for transmission by means of modulated continuous light. In addition, the measurement information during pulse transmission cannot be falsified by variable attenuations of the transmission path.
  • the optical transmission path could be a free beam path.
  • a single optical fiber is preferably used, by means of which the measured values are transmitted in chronological succession.
  • One of the measured values is identified in the receiving device with the aid of the identification pulse.
  • measured values have to be transmitted, which can be in the range from zero to a maximum value
  • two successively transmitted optical measuring pulses are sent at a time interval t o + t n ', the constant time t o being greater than t k and the time t n 'depends on the measured value.
  • the minimum possible length of time between successive measurement pulses is certainly greater than the time interval between an identification pulse and the previous measurement pulse, so that a clear identification of the identification pulse can always be achieved at the receiving end.
  • a preferred embodiment of the invention is characterized in that the original measured values are converted into electrical square-wave signals, the duration of which depends in a predetermined manner on the size of the measured values, so that the start of the square-wave signal of the subsequently measured value is initiated by the termination of each square-wave signal and that an identification signal with a constant delay time compared to the start of a square wave signal associated with a predetermined measurement signal is generated.
  • the square-wave signals can subsequently be converted into needle pulses by differentiating stages, which are supplied as a sum signal to a control stage of an LED via a common line.
  • a preferred embodiment of the invention for which only a small amount of electronic circuit elements is required, is characterized in that the needle-pulse-shaped electrical output signals of the optical receiver, if necessary after amplification are converted by means of a flip-flop into square-wave pulses, the duration of which is greater than the delay time t k of the identification pulse and less than the difference between a minimum possible measurement time t 1 or t 2 and the delay time t k that these square-wave pulses are fed to a first input of a first AND gate are, while the input signal of the flip-flop is fed to the second input of the first AND gate, so that in-phase signals are generated at the output of the first AND gate, and that the inverted output signal of the flip-flop and the input signal of the flip-flop to a second AND gate are supplied, at the output of which successive signals are generated in accordance with the time interval between the measuring pulses.
  • the sizes of two measured values m1 and m2 are scanned by means of the capacitive sensors 1 and 2 by means of the transmission device shown in FIG.
  • the transmitting device finally forms optical pulses 3 from the determined capacitance values of the sensors 1 and 2, which are passed into the optical fiber and transmitted to the receiving device shown in FIG. 3.
  • a capacitive pressure sensor consists, for example, of a cylindrical base body, on the end faces of which metallized membranes are arranged, the spacings of which from counter electrodes change depending on the pressure.
  • the transmitting device consists of an oscillator stage 4, a differentiating and decoding stage, which contains the differentiating stages 5, 6 and 7 and a monostable flip-flop 8, and an optical transmitting stage with a light source, which preferably consists of a semiconductor laser diode 10.
  • Rectangular pulses a and b are generated by the oscillator stage 4, as shown in FIG. 2 as a function of time.
  • the time length t1 of each pulse a contains the information about the size of the capacitance of the sensor 1 and thus about the measured variable m1.
  • the time length t2 of the pulse b is a measure of the measured value m2.
  • a rectangular pulse sequence c ( Figure 2) is passed to the differentiating stage 6, at whose output a current pulse sequence f of Figure 2 institute.Der start of pulses c at the time t k with respect to the beginning of the to be identified Impulse b delayed.
  • the delay time t k can be predetermined by the capacitance C 1 and the resistor R 1. It must be less than the minimum possible value of the times t 1 and t 2.
  • tn t O + t1 ′
  • t2 t O + t2 ′.
  • the time t n contains the information about the nth measured value.
  • the fixed time t o results from the fact that the capacitances of sensors 1 and 2 already have a finite value if the measured variables m1 and / or m2 have the value zero.
  • the diodes D1, D2 and D3 suppress negative signals, so that a voltage sum signal according to g according to FIG. 2 is present at the control connection of the electronic switch 9, which voltage voltage consists of the sum of the needle-shaped signals d, e and f.
  • the light source is connected to the DC voltage U via the switch 9.
  • the light source 10 forms optical needle signals 3, which have the chronological sequence of the signals g according to FIG. 2.
  • the capacitor C2 which had previously been charged via the charging resistor R2, is discharged very quickly via the light source.
  • the short-term but high current flow through the light source then generates an optical pulse.
  • C2 can then recharge via R 2.
  • the average power consumption is low because the light source is only connected for a short time.
  • the peak current required to generate high optical pulses is taken from capacitor C2 to reduce the load on the voltage source.
  • a voltage Uo which is constantly regulated by a circuit, not shown, is required for the power supply of stages 4 to 8. Overall, only an average current of about 30 uA is required to power the entire transmitter.
  • the optical pulse signals 3, which run according to g in FIG. 2, are passed to the photodiode 11 of the receiving device shown in FIG Signals a and b correspond to Figure 2.
  • the output signals o and p are fed together with intermediate signals k and l to an evaluation circuit (not shown), at whose output a DC voltage proportional to the difference between the measured values (m1-m2) is then output.
  • an evaluation circuit can be constructed in a manner known to those skilled in the art, for example in the manner described in the earlier application P 35 28 416.1. In this way, for example, a pressure difference of a differential pressure sensor can be read directly.
  • the photodiode 11 of the photo amplifier 12 is followed by a current-voltage converter.
  • the photodiode 11 generates an electrical current from the optical signal, which then appears as a voltage signal at the output of the operational amplifier OP1.
  • This signal h is amplified again with the operational amplifier OP2.
  • the DC signal is separated in this stage with the capacitor C3 so that the dark current of the photodiode 11 and offset currents of the operational amplifier OP1 have no influence.
  • the signal is limited with the Zener diode D4 so that no overdrive can occur.
  • the comparator K then generates a TTL-compatible pulse signal i (see FIG. 4).
  • a reference voltage is generated with the resistors R3 and R4.
  • the comparator K switches when the input signal is larger than the reference signal. Interference signals contained in the signal h which are smaller than the reference signal are thus suppressed.
  • the needle pulse-shaped output signal of the comparator K now passes through the decoding circuit 13. There, the rectangular original signal is regenerated from the needle pulses.
  • the pulse diagram of this stage is shown in FIG. 4.
  • the monostable flip-flop reacts to the falling edge of the needle pulses i of the comparator K.
  • the pulse time t m of the monostable flip-flop MFF must be greater than the time t k and less than the time t 2.
  • the non-inverted output signal of the monostable flip-flop MFF reaches the gate U1, to which the needle pulse signal is also present.
  • the gate U1 then ensures that only the additional pulse of the needle pulse signal is passed on. This signal then reaches the reset input of the D flip-flop DFF.
  • the inverted output signal of the monostable flip-flop MFF reaches the gate U2. At its output the needle pulse signal appears without the additional pulse. This signal is now sent to the "clock" input of the D flip-flop, which works as a bistable flip-flop, which means that it jumps with every needle pulse.
  • a square-wave signal then appears at the output Q of the D flip-flop, the pulse time being high corresponding to the pulse time t 1 and thus the sensor capacitance C1 and the pulse time at low level corresponding to C2.
  • the correct assignment takes place with the additional pulse, which was blanked with the gate U1 and is at the reset input of the D flip-flop D-FF. This pulse appearing in time t 2 forces a reset of the D flip flop, so that a low level appears at output Q during this time.
  • the invention was explained on the basis of the description of a transmission of only two measured values for simplicity of illustration.
  • An advantageous application example is the pressure difference measurement.
  • it is advantageous not to transmit the value of the pressure difference directly, but rather the individual pressure values.
  • the energy expenditure for electronic conversion and evaluation of the pressure values for the pressure difference value can be delivered at the receiving end.
  • the circuits shown can be modified in a manner familiar to the person skilled in the art in order to be able to transmit more than two measured values, even then only one identification pulse being required.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Arrangements For Transmission Of Measured Signals (AREA)
  • Optical Communication System (AREA)

Claims (7)

  1. Procédé pour la transmission de valeurs de mesure issues au moins de deux détecteurs, au moyen d'impulsions lumineuses envoyées à partir d'un transmetteur optique vers un récepteur optique par un trajet de transmission optique et dont la distance dans le temps est évaluée comme mesure de la valeur de mesure, caractérisé en ce que les valeurs de mesure (m1, m2) sont toujours transmises dans le même ordre de succession et cycliquement les unes immédiatement après les autres, en ce que par valeur de mesure est transmise une impulsion optique de mesure dont la distance dans le temps (t₁, t₂) par rapport à une impulsion optique de mesure associée à une valeur de mesure précédente constitue une mesure de la grandeur de la valeur de mesure, et en ce que pour chaque cycle de valeurs de mesure est transmise une impulsion d'identification dont la distance dans le temps (tk) par rapport à une impulsion optique de mesure associée à une valeur de mesure précédente est inférieure à la plus petite distance possible dans le temps entre deux impulsions de mesure optiques.
  2. Procédé selon la revendication 1, caractérisé en ce que deux impulsions de mesure optiques successivement transmises sont émises avec une distance dans le temps de to + tn', le temps constant to étant supérieur à tk et le temps tn' étant dépendant de la valeur de mesure.
  3. Procédé selon la revendication 1 ou 2 , caractérisé en ce que le trajet de transmission est constitué par un seul guide de lumière à l'entrée duquel les impulsions de mesure ainsi que l'impulsion d'identification sont introduites par une source lumineuse, notamment une diode laser semiconductrice (10) pour être dirigées vers un photodétecteur (11).
  4. Procédé selon l'une des revendications 1 à 3, caractérisé en ce que les valeurs de mesure originales (m₁, m₂) sont converties en signaux électriques rectangulalres (a, b) dont la durée (t₁, t₂) d'une manière prédéterminée est dépendante de la grandeur de la valeur de mesure, en ce que le début d'un signal rectangulaire (a ou b) de la suivante valeur de mesure est introduite par la fin de chaque signal rectangulaire (a ou b) et en ce qu'est engendré un signal d'identification (c, f) à un retard constant tk par rapport au début du signal rectangulaire (b) associé à un signal de mesure prédéterminée (m₂).
  5. Procédé selon la revendication 4, caractérisé en ce que les signaux rectangulaires (a, b, c) sont convertis en impulsions en pointe par des étages différenciateurs (5, 6, 7).
  6. Procédé selon la revendication 5, caractérisé en ce que les impulsions en pointe (d, e, f) sont appliquées par un conducteur commun à un étage de commande (9), à une DEL ou à une diode semiconductrice 10.
  7. Procédé selon l'une des revendications 1 à 6, caractérisé en ce que les signaux de sortie électriques en forme d'impulsion en pointe du récepteur optique (12) sont convertis le cas échéant après amplification au moyen d'un multivibrateur (MFF) en impulsions rectangulaires dont la durée tm est supérieure au retard tk et inférieur à la différence entre un temps de mesure t₁ ou t₂ aussi court que possible et le retard tk, en ce que ces impulsions rectangulaires (k) sont appliquées à une première entrée d'une première porte ET (U1), alors que le signal d'entrée (i) du multivibrateur (MFF) est appliqué à l'autre entrée de la première porte ET, de sorte que sur la sortie de la première porte ET apparaissent des signaux (m) présentant la même phase que les impulsions d'identification (f), et en ce que le signal de sortie inversé (1) et le signal d'entrée (i) du multivibrateur (MFF) sont appliqués à une seconde porte ET (U2) sur la sortie de laquelle apparaissent des signaux en pointe successifs (n) en conformité avec la distance dans le temps entre les impulsions de mesure.
EP87200161A 1986-02-07 1987-02-03 Méthode pour la transmission de signaux de mesure d'au moins deux transducteurs par liaison à transmission optique Expired - Lifetime EP0231980B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3603800 1986-02-07
DE19863603800 DE3603800A1 (de) 1986-02-07 1986-02-07 Verfahren zur uebertragung von mindestens zwei messwerten ueber eine optische uebertragungsstrecke

Publications (3)

Publication Number Publication Date
EP0231980A2 EP0231980A2 (fr) 1987-08-12
EP0231980A3 EP0231980A3 (en) 1989-08-02
EP0231980B1 true EP0231980B1 (fr) 1993-10-13

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Application Number Title Priority Date Filing Date
EP87200161A Expired - Lifetime EP0231980B1 (fr) 1986-02-07 1987-02-03 Méthode pour la transmission de signaux de mesure d'au moins deux transducteurs par liaison à transmission optique

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US (1) US4864648A (fr)
EP (1) EP0231980B1 (fr)
JP (1) JPS62186398A (fr)
DE (2) DE3603800A1 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3937572A1 (de) * 1989-11-11 1991-05-16 Hartmann & Laemmle Elektronisc Einrichtung zur uebertragung mindestens zweier als impulsfolgen erzeugter informationssignale
DE4215167A1 (de) * 1992-05-08 1993-11-11 Bayerische Motoren Werke Ag Faseroptische Vorrichtung in Kraftfahrzeugen
US5460182A (en) * 1992-09-14 1995-10-24 Sextant Medical Corporation Tissue penetrating apparatus and methods
US5762609A (en) * 1992-09-14 1998-06-09 Sextant Medical Corporation Device and method for analysis of surgical tissue interventions
US5772597A (en) * 1992-09-14 1998-06-30 Sextant Medical Corporation Surgical tool end effector
JP3320996B2 (ja) * 1996-11-26 2002-09-03 株式会社東芝 波長多重光伝送装置
FI115677B (fi) 2003-12-19 2005-06-15 Suunto Oy Rannetietokone

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2643949C3 (de) * 1976-09-29 1981-06-19 Siemens AG, 1000 Berlin und 8000 München Schaltungsanordnung zum impulsmäßigen Übertragen von analogen Spannungswerten beider Polaritäten
DE3138073A1 (de) * 1981-09-24 1983-04-14 Siemens AG, 1000 Berlin und 8000 München Anordnung zur uebertragung von messwerten zu einer entfernten stelle
DE3138074A1 (de) * 1981-09-24 1983-04-14 Siemens AG, 1000 Berlin und 8000 München Anordnung zur uebertragung von messwerten zu einer entfernten stelle
JPS58154097A (ja) * 1982-03-08 1983-09-13 横河電機株式会社 光学伝送システム
US4513403A (en) * 1982-08-04 1985-04-23 Exploration Logging, Inc. Data encoding and synchronization for pulse telemetry
US4694504A (en) * 1985-06-03 1987-09-15 Itt Electro Optical Products, A Division Of Itt Corporation Synchronous, asynchronous, and data rate transparent fiber optic communications link
DE3528416C2 (de) * 1985-08-08 1996-04-18 Envec Mess Und Regeltechn Gmbh Auswerteschaltung für einen kapazitiven Sensor

Also Published As

Publication number Publication date
DE3787735D1 (de) 1993-11-18
EP0231980A2 (fr) 1987-08-12
DE3603800A1 (de) 1987-08-13
JPS62186398A (ja) 1987-08-14
EP0231980A3 (en) 1989-08-02
US4864648A (en) 1989-09-05

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