EP0327403A2 - Stellungsüberwachungsanordnung - Google Patents

Stellungsüberwachungsanordnung Download PDF

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Publication number
EP0327403A2
EP0327403A2 EP89301112A EP89301112A EP0327403A2 EP 0327403 A2 EP0327403 A2 EP 0327403A2 EP 89301112 A EP89301112 A EP 89301112A EP 89301112 A EP89301112 A EP 89301112A EP 0327403 A2 EP0327403 A2 EP 0327403A2
Authority
EP
European Patent Office
Prior art keywords
switch
output
monitoring system
terminal
signal
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Withdrawn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
EP89301112A
Other languages
English (en)
French (fr)
Other versions
EP0327403A3 (de
Inventor
Christopher James Brawn
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.)
ZF International UK Ltd
Original Assignee
Lucas Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lucas Industries Ltd filed Critical Lucas Industries Ltd
Publication of EP0327403A2 publication Critical patent/EP0327403A2/de
Publication of EP0327403A3 publication Critical patent/EP0327403A3/de
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
    • H01H9/16—Indicators for switching condition, e.g. "on" or "off"
    • H01H9/167—Circuits for remote indication

Definitions

  • This invention relates to a condition monitoring system and has particular reference, but not sole reference, to a system for monitoring the positions of switches in a car or other vehicle.
  • Hitherto known switch monitoring systems either drive a small current continuously through each switch being monitored, or drive a large current through the switch momentarily.
  • the total current consumption over a period of time can be excessive and cause the vehicle battery to be discharged if the vehicle is left at rest for too many days.
  • the drive signal is of fixed duration and the monitoring unit has to respond immediately otherwise it will fail to read the condition of the switch.
  • condition monitoring system arranged to provide at least first and second output drives to a device to be monitored and to receive at least first and second input signals from the monitored device, said device having a plurality of states and the system being further arranged to respond to the received input signals to select which output drive signal is applied to the device so that little or no current is drawn from the monitoring system by the device when the device is in any of its said states.
  • the device being monitored is a two-state or two-position switch.
  • the switch receives a low level output signal from the monitoring system so that it draws little or no current.
  • the switch changes position, it receives a high level output signal via the new contact which is made, but an input of the monitoring system res­ponds to this in order to apply a low level signal to the newly made contact. This ensures that little or no current is drawn by the switch in its new position.
  • the system may be used in a vehicle to monitor lock switches in a central door locking system, or door switches controlling courtesy lamps.
  • the system mini­mises the consumption of current. An instant of where this is particularly important is in the case of vehicles fitted with a burglar alarm system having a back-up battery, because the battery would be drained quite quickly if all the switches were continually drawing current.
  • a system for monitoring the condition of a switch SW which in this case comprises a two-position or two-state switch having a contact 10 connected at one end to a common point C and movable so that it makes either with point A or point B.
  • the switch SW may form a lock switch in a central door locking system or a door switch controlling a courtesy lamp.
  • the system will comprise a plurality of switches such as switch SW, each with its own set of the components shown which interconnect the switch SW with a central con­troller 20.
  • the controller 20 has an output OUT driving a buffer B1 the output of which is connected to the switch contact A.
  • the controller output also drives an inverting buffer B2 having its output connected to the switch contact B.
  • the common point C of the switch is connected through a buffer B3 to an input IN of the controller.
  • the controller 20 senses at step 100 whether the input IN is active (i.e. receiving current). Normally the input IN will be inactive: thus whilst the switch SW is in position A normally the out­put OUT of the controller will be providing a low level signal so that no current will pass through buffer B2 and switch 10 (via contact A) and buffer B3 to the controller input. So if at step 100 the input is found to be inactive, the controller 20 simply repeats step 100.
  • Step 110 will then check the status of the output OUT and, find­ing it inactive, the controller will sense at step 120 that the switch is now in position B.
  • the controller responds by driving the output OUT active i.e. to produce a high level signal.
  • the output of inverting buffer B2 is now at low level so that no current flows from this through the switch and back to the controller input. Accordingly, the input IN remains inactive and step 100 will be repeated again until the switch is changed back from position B to position A.
  • step 100 When eventually the switch is changed from position B to position A, step 100 will find that the input has become active, i.e. the high level which has been pre­vailing on the output OUT will now cause current to pass through buffer B1 and the switch (via contact A) and buffer B3 to the controller input IN.
  • Step 110 then checks and on finding that the output is in its active condition, the controller determines that the switch is now in position A (step 130). Consequently, step 135 drives the output OUT to its inactive state. In this condition, no current is available to flow through buffer B2 and the switch contact A back to the controller input.
  • the controller may comprise a hardware logic circuit or it may comprise a microprocessor, in either case having a low power mode which it normally adopts together with means for responding to the input IN to switch it to a high power mode for effecting the changeover action and then to return it to the low power mode immediately afterwards.
  • FIG. 3 there is shown a modified monitoring system which responds to output sensing rather than input sensing of the central controller 20.
  • the output OUT of the controller drives the switch contacts A and B through buffer B1 and inverting buffer B2 as in the system of Figure 1, but the common contact C of the switch is con­nected to ground. Also the contacts A and B are connected to respective inputs INA and INB of the controller through buffer B4 and B5.
  • step 200 the output is driven active. Current fails to flow through the switch (contact A being broken), so that step 210 indicates that INA is active. Under this condition step 210 is repeated. Eventually however when the switch is changed from position B to position A, current will pass through buffer B1 and the switch to bring the input of buffer B4 to low level. Step 210 now finds that INA is inactive and step 220 determines that the switch is now in position A. Accordingly step 230 responds by driving the output inactive. This prevents current from flowing through buffer B1 and the switch via contact A. Step 240 will now monitor input INB repetitively, finding it active (high level), because inverting buffer B2 provides a high level signal which is sensed via buffer B5.
  • step 240 Eventually when the switch is changed from position A to position B, step 240 will find that input INB has become inactive and step 250 determines that the switch is now in position B. Step 260 responds to drive the output OUT active. Now with the output at high level, the output of buffer B2 is low so no current is drawn through the switch and mean­while the output of buffer B1 is high and the input INA registers as active. The controller now returns to the step 210, in effect monitoring for the next change in state of the switch SW.
  • all inputs are high impedance inputs and all outputs are push-pull drivers.
  • the "output” and "inverted output” signals may be generated separately within the controller.

Landscapes

  • Arrangements For Transmission Of Measured Signals (AREA)
  • Keying Circuit Devices (AREA)
EP19890301112 1988-02-05 1989-02-03 Stellungsüberwachungsanordnung Withdrawn EP0327403A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8802625 1988-02-05
GB888802625A GB8802625D0 (en) 1988-02-05 1988-02-05 Condition monitoring system

Publications (2)

Publication Number Publication Date
EP0327403A2 true EP0327403A2 (de) 1989-08-09
EP0327403A3 EP0327403A3 (de) 1990-12-05

Family

ID=10631148

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890301112 Withdrawn EP0327403A3 (de) 1988-02-05 1989-02-03 Stellungsüberwachungsanordnung

Country Status (2)

Country Link
EP (1) EP0327403A3 (de)
GB (1) GB8802625D0 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997025729A1 (en) * 1996-01-11 1997-07-17 Fusion Meters Limited Switch status sensor
GB2350951A (en) * 1999-06-07 2000-12-13 Ford Motor Co Improved CMOS mechanical switch monitor circuit

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1157296B (de) * 1959-04-21 1963-11-14 Bbc Brown Boveri & Cie Rueckmelde- und Kontrollanordnung fuer die Schaltstellung eines Schuetzes oder fuer die Stellung eines mechanischen Geraetes
DE3001940C2 (de) * 1980-01-21 1983-01-27 Siemens AG, 1000 Berlin und 8000 München Anordnung zur Ermittlung der Schaltstellung eines Schalters und zur Überwachung der zugehörigen Leitung auf Kurzschluß und Unterbrechung
DE3228686A1 (de) * 1982-07-31 1984-02-02 Edmund 7016 Gerlingen Zottnik Verfahren und vorrichtung zur erfassung von sdchalterstellungen
FR2536903B1 (fr) * 1982-11-29 1985-10-25 Commissariat Energie Atomique Dispositif de controle de l'etat d'un commutateur

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997025729A1 (en) * 1996-01-11 1997-07-17 Fusion Meters Limited Switch status sensor
US6255748B1 (en) 1996-01-11 2001-07-03 Fusion Meters Limited Switch status sensor
GB2350951A (en) * 1999-06-07 2000-12-13 Ford Motor Co Improved CMOS mechanical switch monitor circuit

Also Published As

Publication number Publication date
EP0327403A3 (de) 1990-12-05
GB8802625D0 (en) 1988-03-02

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