FR2792782A1 - Detection circuit for switch state monitoring, has common detector for several monitored units producing identical wake-up signal for any originating unit or state change - Google Patents

Abstract

Signals (X1,X2,X3) produced by any of e.g. 3 monitored units have separate inputs to a shared transmitter (D1). Changes in any one of them, due to an altered switching state, cause the transmitter to produce an output signal (Xe) which is applied to the inputs of two pulse-forming stages (I1,I2). One stage (I1) responds to a rising, the other (I2) to a falling front, in such a way that the output signal pulses (Xp1,Xp2) of both are identical in form. These outputs constitute the inputs to an OR gate (D2) producing the wake-up signal (Y). Energy consumption in the inactive mode is negligible, and in the active mode is minimized by choosing a pulse width low (e.g. 50-500 microseconds) compared to the interval between pulses (e.g. 5-20 ms).

Description

The invention relates to a circuit arrangement for the detection of

  switching of at least one actuating means, in particular switches used for activating an electronic circuit of a motor vehicle. Such circuit arrangements are used in automotive technology to control functions of the electrical circuit of a vehicle in a manner dependent on different switches, more specifically locks, for example door contact, trunk closing, contact lock, closing. tank, etc., and

  their respective switching states.

  For reasons of energy saving, such circuit arrangements include an active mode, in which the respective switching states of the various switches, more specifically locks, can be detected, and a rest mode. (or "sleep mode" = sleep mode) in which the energy supply is most of the time reduced compared to the active mode. In this rest mode, only the entry of a specific action is monitored and, in the event of entry, a wake-up signal is produced, in order to make

  thus switching the circuit arrangement to active mode.

  For this purpose, in DE 44 14 734 C2, it is for example the actuation of the handle of the driver's door

  which is monitored appropriately.

  However, in practice, there may be operating faults, such as for example a door left in error for too long open with the door contact monitored, and faulty operation of switches, for example a switch remaining "stuck", so that the corresponding switches or contacts remain in an undesired switching state and can no longer be used to produce

a wake-up signal.

  Furthermore, in the telecommunications technique, for example in DD 53160, DE 20 21 971 B2 and DE-S2005 / 21a, circuit arrangements are known which make it possible to detect a change in the switching state of a means d actuation. However, such circuit arrangements have the disadvantage of not having a rest mode with reduced energy consumption, so that it is necessary to fear the exhaustion of an autonomous energy source, for example an automobile battery. . This is why the invention aims to provide a circuit arrangement and a method for the detection of switching states of at least one actuating means, in particular of switches used for activating a circuit. motor vehicle electronics, which ensure, with low energy consumption, the production of a wake-up signal in a rest mode, even in the case of such faults

  faulty operation or operations.

  To this end, the subject of the invention is a circuit arrangement for the detection of switching states of at least one actuation means, in particular of switches used for activating an electronic circuit of a motor vehicle, comprising an idle mode and an active mode, characterized in that in idle mode, the circuit arrangement produces a wake-up signal when at least one actuating means changes from a first defined switching state to a second switching state defined, the circuit arrangement is arranged so as to produce the wake-up signal even when the second switching state changes to the first switching state and the circuit arrangement is arranged so as to present, in its resting mode, a

  practically zero energy consumption.

  For the same purpose, the invention also relates to a method for the detection of switching states of at least one actuating means, in particular of switches used for activating an electronic circuit of a motor vehicle, according to which, for at least one actuating means comprising at least two switching states, a respective different value is associated with each switching state, characterized in that each change in the values is transformed, in a rest mode in which the energy consumption is

  practically zero, in a wake-up signal.

  Thus, any change in the switching state of one or more switches is monitored, in such a way that a maneuvering fault, such as for example a door remaining by mistake too long open, causes, after its closing. , a change in the switching state of the door contact and produces a wake-up signal. A wake-up signal can also be produced when, despite closing the door in the manner provided, the door contact remains stuck in its previous switching state (door open) and is released by a new actuation,

  so that it signals a closing of the door.

  According to one embodiment of the invention, the wake-up signal can be produced by a change in a switching state of at least two switches, independently of one another. This provides assurance that, even in the event of a complete failure or permanent malfunction of a switch, a wake-up signal can be as

  previously produced in a safe manner.

  According to the invention, the quiescent current in sleep mode is limited to a practically zero value. In active mode, for reasons of energy saving, it is possible that a switched or pulsed energy supply is used instead of a permanent energy supply and that consumption

  energy is advantageously reduced.

  This advantageous effect also occurs without monitoring any change in the switching state of at least one switch, but it is however described in detail only in the context of such a circuit arrangement. However, it is also possible to envisage correspondingly limiting the energy consumption of a conventional circuit arrangement in sleep mode to a practically zero value. The circuit arrangement according to the invention can also have one or more of the following features: - the wake-up signal can be produced by a change in a switching state of at least one of several actuation means , independently of the switching state of the other actuating means, - the circuit arrangement includes an active mode making it possible to detect the switching state of each individual actuating means which can be activated by means of the wake-up signal , - in active mode, a pulsed energy source is activated, - the pulses of the energy source have a pulse width between 50 and 500 gs and consist, between the individual pulses, in intervals between 5 and 20 ms, the circuit arrangement comprises, for the actuation means or means, a first circuit comprising a first pulse-forming stage, in order to produce a wake-up signal during a transition from the first state switching to the second switching state, and comprises, in a second circuit, a second pulse-forming stage comprising an inverter, in order to produce the wake-up signal when passing from the second switching state to the first switching state , - the first and second circuits partially overlap, - the second circuit includes the training stage

of pulses from the first circuit.

  The invention is described below in detail using

  examples of implementation shown in the drawings.

  On these, we see: in Figure 1, a block diagram of the general operation of a circuit arrangement according to the invention, in Figure 2, a connection diagram of

  the circuit arrangement for making a diagram

  block according to Figure 1 and, in Figure 3, a block diagram of the variation

  signals in a circuit according to figure 2.

  The circuit arrangement of Figure 1 comprises, for monitoring input signals X1, X2 and X3, two stages of pulse formation Il and I2 and a shared transmission unit D1. The signals Xl, X2 and X3 are applied, independently of one another, to the inputs of the shared transmission unit D1, which delivers any change in an input signal Xl, X2 or X3

as a signal Xe.

  The output of the shared transmission unit D1 is connected to the two inputs of the pulse-forming stages Il and I2, so that the signal Xe is applied both to the input of the pulse-forming stage Il at the entrance of the pulse formation stage I2. Stage II transforms a rising flank into a defined pulse and stage I2 transforms a descending flank into a pulse corresponding to the pulse of Il, therefore for example into a pulse

  positive Xpl, Xp2, as shown in the drawing.

  These respective positive pulses Xpl and Xp2 are combined, by means of an OR gate D2, to give the signal Y, namely the wake-up pulse. Of course, instead of being described by means of two stages of pulse formation Il and I2 and of the connection of their outputs by means of a gate D2, this function could also be described in an equivalent manner in the form of an equivalent circuit comprising only one stage of pulse formation which transforms both a positive flank and a negative flank respectively into

an impulse of the same form.

  According to the invention, the input signals X1, X2, X3 are due to a change in a switching state

  an actuating means, as explained above

  after. Of course, the number of input signals is not limited to Xl to X3, so that, depending on what is desired and depending on the field of application, it is possible to combine any number of signals input by means of Dl to give a signal Xe, without other stages of pulse formation being

necessary for this purpose.

  FIG. 2 represents, in the form of a diagram of

  connection, an embodiment of the block diagram of Figure 1.

  At the input X1, the circuit arrangement includes a switch S1, one side of which is connected to ground and the other side of which is connected, at a point 1, to the two cathodes of two decoupling diodes D12 and D13. On the anode side, the diode D12 is connected, with one side of a capacitor Cl1, at a point 1 'and at the same time, via a resistor R12, to a power supply of for example 12 V. The other side of the capacitor Cll is connected, at a point 1 "and via a resistor R01, to the + 12 V power supply and at the same time, at a point 2", to a side d '' a capacitor C21, to a collector of an NPN transistor T01 and, via a base resistor R02, to a base of a PNP transistor

T02.

  On the emitter side, the transistor T01 is grounded and, on the emitter side, the transistor T02 is connected to the + 12 V power supply. The collector of T02 constitutes the output for the output signal Y, this collector being at the mass via the resistor R03. At input X2, the circuit arrangement includes a switch S2 which, on the one hand, is grounded and, on the other hand, is connected, by a point 2 "'and

  in point 2, with the two diode cathodes D22 and D23.

  On the anode side, diode D22 is connected, at point 2 ', to the side of capacitor C21 located opposite point 2 "and at the same time, via a resistor R22, to the power supply + 12 V. R01 constitutes the resistance by which each of the capacitors Cll and C21 are charged, R12 the discharge resistance of Cil and R22 the discharge resistance of C21. The switch S2 is connected, by a point 2 "', to one side of a capacitor C22, the other side of which is connected, via a resistor R26, to the base of the transistor TO1. This base is itself grounded by

  through a resistor R27.

  At input X3, the circuit arrangement includes a switch S3 which is connected on the one hand to the + 12 V power supply and on the other hand, by a point 3, to one side of a capacitor C32 and at the same time

  to ground via a resistor R32.

  The other side of capacitor C32 is connected, likewise

  as R26 and R27, at the base of transistor TO1.

  The operation of this circuit arrangement of FIG. 2 is explained below using the diagram

signal passing in figure 3.

  The input signals X1 and X2 are each produced by means of a switch which, when closed, allows a connection to ground, so that, when the switch S1 is closed, a negative edge is present at the connection point of the cathodes of D12 and D13 and, because of its opening, a positive flank appears as a signal Xi. Similarly, the signal X2 is present at connection point 2 of the cathodes of D22 and D23. On the other hand, the switch corresponding to the input signal X3 is produced in the form of a switch which, when closed, allows connection at a high level, for example + 12 V, so that its closure causes the presence of a positive flank at point 3 and its opening that of a negative flank. If the switch corresponding to X2 closes allowing a ground connection, for example due to an actuation of the door contact due to an opening of the door, there is at points 2 and 2 'a corresponding negative edge to the signal 2al of FIG. 3, which is derived by means of the capacitor to give a negative Dirac pulse 2a2. This negative Dirac pulse is applied via the base resistor R02 to the base of the PNP transistor T02 and controls the latter until, under the effect of its charge, the capacitor C21 limits the current passing through to such an extent that a value exceeding the threshold value of transistor T02 occurs at point 2 "and again makes this transistor non-conductive. The discharge time is thus essentially determined by the RC circuit R01-C21, given that for this purpose, the current flow through the emitter of transistor T02 towards the base of the latter by crossing the basic resistance R02 is relatively weak. At the output Y which, in the normal case, is connected to the ground by R02, there is, under the effect of the conduction and non-conduction of the transistor T02, a positive pulse 2a3 conforming to

Figure 3.

  If the switch corresponding to X2 remains closed for longer, points 2 and 2 'remain, as described above, at the LOW level (ground) and point 2 ", once the charge of C21 has been completed, at level + 12 V. If then the switch of X2 is opened again, the points 2, 2 ′ are therefore at a level of 12 V and the point 2 "also remains at this level, so that the capacitor

  C21 discharges again through R22.

  On the other hand, during the opening, the level of point 2 "', which was at 0 V when closing, also changes to + 12 V (signal 2bl). The capacitor C22, which, when closing the switch X2, had discharged to ground through it, then charges again essentially through R26 and R27 and, to a greater extent

  weaker, negligible, using base current

  emitter of transistor Ti01, so that a positive level is applied to the base of transistor NPN T01 and makes it conductive, until the capacitor C22 is charged to a point such that the basic voltage increases below the threshold value of transistor T01 (signal 2b2). Finally, because of this, there is a negative pulse 2b3 on the collector of transistor T01 which, through the basic resistance R02, makes the transistor T02 conductive and non-conductive, so that the signal 2b3 is inverted and gives the output Y a

signal in the form of 2a3.

  The variation of the signal of Xl differs from the signal of X2 which has just been described only by the fact that it does not occur in this case of connection location, corresponding to point 2 "', towards the base of the transistor T01i, more precisely to the RC circuit connected upstream. On the other hand, points 1, 1 'and 1 "correspond to points 2, 2' and 2". It follows that the levels applied at 1, 1 'and 1 " when the switch of Xl is closed correspond to the levels of points 2, 2 'and 2 "when the switch of X2 is closed and therefore also cause a positive pulse having the form to appear at output Y of 2a3. Since there is no point corresponding to point 2 "', it does not occur, in this circuit arrangement and during the transition from the closed state to the open state of the X2, no corresponding command of the transistor Ti01 making it conductive and non-conductive. Of course, it is however possible to imagine providing such a connection point corresponding to point 2 "'and also providing for X1 a wake-up signal as well

  for a falling edge than for a rising edge.

  For X3, a level of 0 V is applied at point 3, through R31, when the switch is open, this level passing to the level + 12 V when the switch closes allowing a connection to this level + 12 V ( signal 3al). The capacitor C32, discharged in the quiescent state, is then charged through R32 and R27, so that a positive level is applied to the base of the NPN transistor TOi, which was previously at a zero level through R27, and makes this transistor T01 conductive. This command in the conductive state is present until the capacitor C32 is charged to such a point (signal 3a2) that the level on the basis of T01 drops below the threshold value and again makes T01 not driver. In this way, there is a negative pulse on the collector of TOi in the form of 2b3, which, as previously described, is reversed by giving on the

  output Y a positive pulse in the form of 2a3.

  When the switch of X3 opens, the base of TOi remains, through R27, at a level of O V and the capacitor C32 previously charged discharges towards the

  ground through resistance R31.

  In the circuit represented in FIG. 2, it is for example only at input X2 that the production of a wake-up signal is carried out during any changes in the switching state of the switch of X2, whereas, on the other hand, for Xl and X3, it is respectively only a change by negative flank in the case of X1 and by positive flank in the case of X3 which is used for the production of a wake-up signal. It could of course be provided for several switches of the type corresponding to X2, but also also several of the type corresponding to X1 and / or X3, depending on the field of application of such a circuit. Similarly, the number of input signals, more precisely switches, could be increased or decreased, diodes corresponding to D12 and D22 having to be installed for the decoupling of the circuits. This presents an arbitrary circuit arrangement, which can be widened and can be modified, which can be adapted to the fields

of the most diverse uses.

  As shown in Figure 2, the circuit arrangement includes an additional + 12 VGESCH power supply which can advantageously be switched or pulsed. This is decoupled by means of diodes D12, D13, D22 and D23 vis-à-vis the previously exposed circuit and the + 12 V power supply and is only switched on in active mode. The circuit is for example carried out by means of the application of the wake-up signal by means of a switching unit,

for example a microprocessor.

  Due to the decoupling of the power supplies, the operation of the circuit arrangement is not affected, so that in active mode the switching state of the switch of X1 can be queried by the intermediate of the voltage divider R14 and R15 in Xal, for example by means of a microprocessor, since, when the switch X1 is open, there is a positive level in Xal, having for example the form of a pulse , which, when the switch of Xl is closed, changes to a zero signal (for example in the form of a low level pulse). The signals present in Xal and Xa2 depend in active mode on the energy source used and, in the embodiment, thanks to the pulsed + 12 V_GESCH energy source, they are in the form of a pulse (level high or low). However, it would also be possible to imagine producing constant levels (high or low) for Xal and Xa2 using a

  permanent energy source in active mode.

  Regarding the switch corresponding to

  X2, the signal at Xa2 behaves in an analogous way.

  On the other hand, X3 should be considered as a special case in which the circuit is not supplied in active mode by the pulsed energy source. In this case, it is only when the switch S3 is closed that a constant high level is applied in Xa3 via a voltage divider R33 and R34. X3 should only indicate that a detailed interrogation of the state of a switch is also possible with a permanent power source, a switch which closes allowing a connection to + 12V can also be used as an alternative instead a switch that closes allowing a ground connection. In this case, as already explained for the rest or sleep mode for the circuits X1, X2 and X3, energy is consumed, except for low leakage currents, only

when a switch is closed.

  Of course, the different circuits for example shown for Xl, X2 and X3 can be combined in any way to give a circuit arrangement and can thus be adapted, in the most different fields, to the respective conditions each time required. In the circuit arrangement shown in the example of implementation, which comprises different superimposed circuits, the energy consumption in rest mode is practically zero, since, in the normal case, all the switches being open , it does not pass current apart from the leakage currents by the diodes, the capacitors and the transistors. In this mode, the switch that produces a wake-up signal is not detected

precisely.

  This wake-up signal can be used to switch on the voltage supply to a microprocessor, for example by means of a voltage regulator. This advantageously makes it possible to limit the energy consumption of a circuit arrangement to practically zero, since this arrangement does not consume energy in

rest mode.

  Increased energy consumption of the circuit arrangement takes place only in active mode, the circuit, now detailed, detecting the switching states of the various switches. However, this increased energy consumption can advantageously be kept at a low value by using a pulsed energy source5 comprising, between the pulses, fairly long intervals in comparison with the pulse width. The

  intervals may be several ms, for example 10 ms. For this purpose, the value of the pulse width can for example be chosen from a range of 50 to 500 gs.

Claims (9)

  1. Circuit arrangement for the detection of switching states of at least one actuating means (Si, S2, S3), in particular of switches used for activating an electronic circuit of a motor vehicle, comprising a rest mode and an active mode, characterized in that: - in rest mode, the circuit arrangement produces a wake-up signal (Y, 2a3) - when at least one actuation means (Si, S2, S3 ) goes from a first defined switching state to a second defined switching state, the circuit arrangement is arranged so as to produce the wake-up signal (Y, 2a3) even when switching from the second switching state to the first switching state and - the circuit arrangement is arranged so as to present, in its idle mode, a consumption of practically zero energy.   2. Circuit arrangement according to claim 1, characterized in that the wake-up signal (Y, 2a3) can be produced by a change in a switching state of at least one of several actuation means (S1 , S2, S3), independently of the switching state of the other actuation means (Si, S2, S3). 3. Circuit arrangement according to any one   claims 1 and 2, characterized in that   the circuit arrangement comprises an active mode making it possible to detect the switching state of each individual actuation means (S1, S2, S3) which can be   activated by means of the wake-up signal (Y, 2a3).   4. Circuit arrangement according to claim 3, characterized in that in active mode, an energy source   pulsed (+ 12 V_GESCH) is activated.   5. Circuit arrangement according to claim 4, characterized in that the pulses of the energy source (+ 12 V_GESCH) have a pulse width between 50 and 500 ys and consist, between the individual pulses, in intervals understood between 5 and 20 ms.   6. Circuit arrangement according to any one   claims 1 to 5, characterized in that   the circuit arrangement comprises, for the actuating means or means (Si, S2, S3), a first circuit comprising a first pulse-forming stage (II), in order to produce a wake-up signal (Y, 2a3 ) upon transition from the first switching state to the second switching state, and comprises, in a second circuit, a second pulse-forming stage (I2) comprising an inverter, in order to produce the wake-up signal (Y, 2a3) when switching from the second switching state to first switching state.   7. Circuit arrangement according to claim 6, characterized in that the first and the second circuits are partially overlap.   8. Circuit arrangement according to claim 7, characterized in that the second circuit comprises the stage   of pulse formation (Il) of the first circuit.   9. Method for the detection of switching states of at least one actuating means (S1, S2, S3), in particular of switches used for activating an electronic circuit of a motor vehicle, according to which, for at least one actuating means (Si, S2, S3) comprising at least two switching states, a different value (0, + 12 V) respective is associated with each switching state, characterized in that each change of values ( 0 - 12 V, 12 - 0 V) is transformed, in a quiescent mode in which the energy consumption is practically zero, into a wake-up signal (Y, 2a3).