DE102006043839A1 - Sensor system for e.g. seat belt lock, of motor vehicle for detecting such as seat position, has sensor devices interconnected with comparator circuit such that information about total-current strength is supplied via signal line of circuit - Google Patents

Abstract

The sensor system (SS) has a sensor device (SE1), which is operated independent of its operating condition with a current strength. Another sensor device (SE2) is operated independent of its operating condition with another current strength. The sensor devices are interconnected with a comparator circuit (KS) such that information about the total-current strength is supplied via a signal line of the comparator circuit. Outputs (A1-A4) of the comparator circuit are supplied to evaluation logic (AL), which determines the operating condition of the sensor devices.

Description

The The present invention relates to a sensor system and a sensor device.

From the DE 42 33 549 A1 is a device for detecting the rotational speed and the direction of rotation of a rotary drive using a rotatably connected to the rotary signaling or signal-changing element, a sensor and an electronic evaluation, in particular for windows and sunroofs in motor vehicles, known. In order to detect the rotational speed and direction of rotation of the rotary drive with high resolution of the rotational speed and direction with a sensor device, the magnetic flux density is periodically changed in a magnetic circuit during rotation of the signal-changing element, wherein the change of the magnetic flux density is rotational direction coded.

to Detecting the periodically changing magnetic flux density In a magnetic circuit, among other Hall sensors as Magnetic sensitive elements are used, where the size and direction the emitted Hall voltage is dependent on the applied magnetic field. Such a Hall sensor often works as a bistable switch, which outputs a positive output signal at its output, if he is penetrated by a magnetic field in a given direction becomes. This signal is retained until the Hall sensor is penetrated by an opposing magnetic field and thus at its output a zero signal is produced. Such Hall sensors are provided in integrated circuits, where for signal shaping additionally Amplifier, Triggers and the like are included.

It is known, the speed and the direction of rotation of a rotary drive by means of two mutually offset by 90 degrees Hall sensors determine in the centric on the rotary drive axis with this one rotatably connected NS magnetized ring magnet is arranged. During the rotation of the ring magnet, the two sides of the Ring magnets arranged Hall sensors each of a variable Magnetic field interspersed, and the occurring at the two sensors thereby magnetic field changes using Schmitt trigger in two offset by 90 degrees binary Pulse trains implemented. By counting The number of pulses per unit time can be the speed and by comparison the two pulse sequences determines the direction of rotation of the rotary drive become.

To capture positions, angular positions and distances of objects, as in the DE 102004024910 B3 described frequently Hall switch assemblies used. For this purpose, for example, a control magnet is brought into the vicinity of a Hall sensor, so that at this due to the changing magnetic field, which results in accordance due to the changed position or the changed distance, a changing measuring voltage, eg Hall voltage is generated. By means of a downstream Schwellwertauswerteschaltung, such as a comparator circuit or a comparator circuit with hysteresis (Schmitt trigger circuit), the change in position by means of control magnets can be digitally detected. So Hall sensors are used as so-called Hall switch assembly for position or distance detection of movable parts. Hall sensor elements or Hall switches are thus also used in particular for use as position or proximity switches in industrial applications and in particular in the automotive sector, these Hall sensors in a motor vehicle, for example for detecting gear shift lever positions, the seat adjustment, the mirror positions, in the buckle, with window regulators , in the sunroof or other applications can be used.

In the following, reference will now be made to the purely schematic in FIG 3 Hall switch element shown 10 explains its basic operation. As in 3 is shown, the Hall switch element 10 a first input terminal 10a for providing a supply voltage Vcc, a second input terminal 10b for providing a reference potential GND, eg ground potential, and an output terminal 10c for providing an output signal OUT. The Hall switch element 10 further comprises a Hall sensor element 12 , a control and supply device 14 and an evaluation and processing device 16 , As in 3 is shown, is the drive and supply device 14 provided to the Hall sensor element 12 to control with a suitable drive signal and also the evaluation and processing device 16 for example, to provide energy. The evaluation and processing device 16 is now provided, for example, to the output signal, for example, the Hall voltage of the Hall sensor element 12 to evaluate, with the evaluation and processing device 16 For example, as a comparator device or a comparator device with hysteresis (Schmitt trigger) is designed to be connected to the output terminal 10c output the output signal OUT, which is a switching state of the Hall switch element 10 represents.

The following will now be based on the 4A -C explains how a typical switching signal OUT of a Hall is obtained switch element. As in 4A is shown, is the Hall switch element 10 For example, the approach or removal of a control magnet or in general any change in a magnetic or a magnetic flux density, the Hall switch element 10 penetrates, represents and is based on a change in position of an object to be observed. The magnetic flux density will now be in the Hall sensor element 12 the Hall scarf terelements 10 in a proportional output voltage, such as a Hall voltage, converted.

If the evaluation and processing device is designed, for example, as a simple comparator device with a switching threshold S0, the result, for example, in FIG 4B illustrated course of the output signal, wherein when passing through the magnetic flux density or the resulting Hall voltage of the switching threshold So, a change in the output voltage, for example, between a first logic level "L" and a second logic level "H", the output signal is caused. A comparison of the magnetic flux density with the switching threshold So means that the output signal, ie the Hall voltage, of the Hall sensor element 12 is compared with a reference voltage as a switching threshold.

In 4C Now, an output signal OUT is shown, which is obtained by a comparator device with hysteresis, wherein an upper threshold S1 and a lower switching threshold S2 is provided, wherein the output signal when the upper threshold S1 passes from the first logic level to the second logic level , and wherein the output signal OUT only changes again from the second logic level to the first logic level when the second lower switching threshold S2 is exceeded. The first and second switching thresholds S1, S2 are, for example, arranged symmetrically about the basic switching threshold So.

The output terminal 10c the Hall switch element 10 is now generally connected to a microprocessor device which the switching signal OUT of the Hall switch element 10 evaluates. As already mentioned above, such Hall switch elements 10 For example, extensively used in automotive technology as a position or proximity switch, which, for example, to determine the gear shift lever position corresponding to the number or resolution of the positions to be detected, a plurality of switches are arranged spatially relatively close to each other. These Hall switch elements 10 However, are relatively far away from the switching state evaluating microprocessor device, such as the on-board computer of a motor vehicle arranged.

According to the prior art is of each Hall switch element 10 moved its own signal line to its own microprocessor input. This provision of a plurality of leads to the microprocessor device presents increased manufacturing overhead and hence increased manufacturing costs. Further, it is necessary for the microprocessor device to have sufficient input terminals to receive each output signal OUT of each Hall switch element 10 having. However, a large number of input terminals to be provided to a microprocessor means that, on the one hand, a relatively complex circuit layout of the microprocessor device is required with a large number of input terminals, and on the other hand, the dimensions of the microprocessor device must be kept relatively large due to the large number of pins, since the Size of a semiconductor chip is mainly determined by the number of pins required.

From the EP 0 363 512 A1 already an arrangement of two series-connected Hall generators is known in which the Hall signal paths are connected in series, resulting in an addition of their signal voltages.

From the DE 41 35 381 A1 For example, a Hall sensor chain is already known in which each Hall sensor has a Hall switch and a drive unit for the same. The Hall switches are activated sequentially and are connected to a common output line.

In the DE 102004024910 B3 a Hall switch arrangement comprises a plurality of series-connected Hall switch elements, wherein a first Hall switch element is designed to provide a first output signal having information about a switching state of the first Hall switch element, and wherein a second, downstream Hall switch element is formed to the first output signal receive the first Hall switch element and to provide a further output signal having the information about the switching state of the first Hall switch element and a further information about a switching state of the second Hall switch element. In this case, a plurality is preferably the same like Hall switch elements arranged concatenated, that is connected in series or cascaded, wherein at least the second Hall switch element or the optional subsequent Hall switch elements have an additional input. In this chain, one input terminal of a subsequent Hall switch element can now be connected to the output terminal of a preceding Hall switch element, wherein the output terminal of the last Hall switch element in the chain is connected to a single microprocessor input.

Of the The invention is based on the object of specifying a technical teaching, by the line overhead for supplying the output signals of a Variety of sensor devices to an evaluation reduced can be.

These The object is solved by the features of the independent claims. advantageous Further developments of the invention are the dependent claims remove.

According to the invention is a Sensor system provided with a first sensor device, the dependent on operated by their operating state with a first or a second current is, with a second Sensorein direction, depending on operated by their operating state with a third or a fourth current is, wherein the first and the second sensor means so with a comparator circuit are interconnected, that information about the Total current, with which the first sensor device is operated and with the second sensor device is operated via a signal line of the Supplied to the comparator circuit be, with the outputs the comparator circuit are supplied to an evaluation logic, and wherein the evaluation logic, in particular a processor device, an application-specific circuit device or a microcontroller, is set up so that it is determined in which operating state the first and / or the second sensor device are located.

The Sensor device, for example, a Hall sensor or a Hall switch include or a Hall sensor or a Hall switch be. The operating state of the sensor device can also by a switching state of the sensor device can be described and can from the physical quantity to be detected, such as a Magnetic field, depend.

The Total current is in particular the sum of the currents with which the first sensor device and the second sensor device are operated.

The first, second, third and fourth current strengths are preferably different.

Preferably:
I1> I2,
I3> I4,
I1 + I4 ≠ I2 + I3,
in which:
I1: first current,
I2: second current,
I3: third current,
I4: fourth current.

at Compliance with these rules is out of the total amperage or a correlated size always derivable, whether the first sensor device with the first or second amperage is operated, and whether the second sensor device with the third or fourth current is operated.

Information about the amperage can by the current strength itself or in the form of a correlating size, for example a voltage, present or signaled.

With the invention it is achieved that with only one signal line information about the operating state of the first and the second sensor device are transmitted to a comparator circuit with downstream evaluation logic. This simultaneous signaling of various information via a signal line is based on a coding of the total current strength such that the information about the individual currents with which the first and the second sensor device are operated by a comparator circuit with downstream corresponding evaluation logic and thus the information about the current operating conditions of the first and the second sensor device can be determined. For this purpose, it is necessary that the two sensor devices each operable with two different currents are.

Preferably the sensor device comprises a switching device, wherein the Sensor device designed in such a way is that the switching device depending on the operating condition the sensor device opened or is closed or will.

Especially simple is the signaling of a total amperage then when the sensor devices are connected in parallel with each other.

Particularly preferably, the comparator circuit is designed such that it outputs at least four output signals. The four output signals can be binary coded, so that a maximum of 16 states can be distinguished by the four output signals. Four of the states can each correspond to the following current intensities, which are simultaneously assigned to the various sensor devices, and thus indicate the current operating states of the two sensor devices.
I1 and I3;
I1 and I4;
I2 and I3;
I2 and I4.

The Evaluation logic is then preferably set up based on is determined on the output signals, in which operating state the first and / or the second sensor device are located. Further Output signals can be used to assess the entire circuit.

Preferably is between the sensor devices and the comparator circuit a conversion circuit connected to the amperage, with the first sensor device is operated, and the current, with the second sensor device is operated, in a representative of the total amperage To convert total voltage signal, which is supplied to the comparator circuit.

Of course it lies It is also within the scope of the invention, in addition to the first and second sensor device provide further sensor devices and this according to the To carry out invention and to override so over a signal line and the operating conditions of these other sensor devices to signal.

As well It is within the scope of the invention, if parts of the sensor system software put into practice.

in the The invention also provides a sensor device with two Power supply inputs, the is set up such that, during operation, it is connected via a first power supply input in dependence of operated in their operating state with a first or a second current and that they are in operation over a second power supply input depending on its operating state operated with a third or a fourth current.

Thereby an implementation of the sensor system according to the invention is based on two identical types, identical or identical sensor devices allows which operated only at different power supply inputs become. Thereby can Sensor devices according to the invention and thus sensor systems according to the invention be put into practice particularly economically.

Preferably the sensor device comprises a switching device, wherein the Sensor device designed in such a way is that the switching device depending on the operating condition the sensor device opened or closed.

in the The invention will now be described by way of example with reference to FIG closer to the following figures explains:

1 shows a simplified schematic diagram of a sensor system;

2 shows a simplified schematic diagram of a sensor device;

3 shows a schematic diagram of a known Hall switch element according to the prior art;

4A -C show the output signal and the switching state of a known Hall switch element according to the prior art.

1 shows a sensor system SS with two sensor devices SE1, SE2. The sensor devices SEI, SE2 each comprise a Hall switch H1, H2 and a resistor R1, R2. Depending on the switching state of the Hall switch H1, H2, the two sensor devices SEI, SE2 are operated in different operating states and with different current intensities.

The first sensor device SE1 is connected to a first current I1 or a second current I2, and the second sensor device SE2 with a third current I3 or a fourth current I4 operated or supplied.

For example:
I1>I2;
I3>I4;
I1 + I4 ≠ I2 + I3.

The current currents I1 or I2 and I3 or I4 are added up and the corresponding from the operating state of the sensor devices SE1, SE2 dependent total amperage a conversion circuit including a series resistor R3, a shunt resistor R4, and an operational amplifier OVU and is supplied with a power source SQ, in one corresponding total voltage implemented.

The current total voltage dependent on the operating state of the sensor devices SE1, SE2 supplied to a comparator circuit KS, the four operational amplifiers OV1, OV2, OV3, OV4 and four reference resistors R7, R8, R9, R10, the operational amplifiers OV1, OV2, OV3, OV4 the supply voltage at the inverting input Supplied to VCC becomes.

At the four signal outputs A1, A2, A3, A4 of the comparator circuit KS are binary coded information about the total voltage and therefore the total current I before, then through a Evaluation logic AL are evaluated, so. that the total current or Total voltage in the current operating states of the sensor devices SE1, SE2, which are binary coded at the logic outputs L1, L2 are output.

In the following, the mode of operation of the sensor system SS is further illustrated by means of an example:
Depending on the operating state, the first sensor device SE1 should be able to be operated with the current intensities I1 = 5 mA and I2 = 15 mA.

The second sensor device SE2 is intended depending on the operating condition with the currents I3 = 6.5 mA and I4 = 13.5 mA be operable.

In the executed Example can optionally by further comparator stages and open leads and short circuits be detected. Open lines are for example characterized in that the total amperage is below the defined values remains (e.g., 0 <I <5mA); Short circuits in that exceeded the defined maximum current is (e.g., I> 28.5 mA).

The following assignments then apply: Total current strength I Operating state of the sensor devices Signals at the logic outputs I1, I2 0 <I <5 mA No Hall sensor connected Error; line break 5 mA <I <6.5 mA - First sensor device SEI (Hall sensor 1) connected - without magnetic field - Second sensor device SE2 (Hall sensor 2) not connected Error; Line interruption sensor 2 6.5 mA <I <11.5 mA - Hall sensor 2 connected - without magnetic field - Hall sensor 1 not connected Error; Line interruption sensor 1 11.5 mA - Both Hall sensors connected - without magnetic field State output 00 21.5 mA - Both Hall sensors connected - Hall sensor 1 with magnetic field - Hall sensor 2 without magnetic field State output 01 18.5 mA - Both Hall sensors connected - Hall sensor 1 without magnetic field - Hall sensor 2 with magnetic field State output 10 28.5m A - Both Hall sensors connected - Hall sensor 1 with magnetic field - Hall sensor 2 with magnetic field State output 11 I> 28.5 mA Short circuit or wrong sensor error

2 shows a sensor device SE3, which, for example, in the just described sensor system SS according to differently connected connected to the location of the first sensor device SE1 and the location of the second sensor device SE2 can occur.

The Sensor device SE3 comprises a Hall switch H3 two diodes D1, D2 and three resistors R10, R11, R12, which are connected to the power supply inputs E1, E2 are interconnected, depending on whether the first power supply input E1 or the second power supply input E2 for power supply is used, depending on from the operating state of the sensor device SE3, the sensor device SE3 with a first current I1 or a second current I2 or a third current I3 or a fourth current I4 is operated.

Claims (8)

Sensor system (SS) with a first sensor device (SE1), which is operated depending on their operating state with a first or a second current strength (I1, I2), with a second sensor device (SE2), depending on their operating state with a third or a fourth current intensity (I3, I4) is operated, wherein the first and the second sensor device (SE1, SE2) are connected in such a way with a comparator circuit (KS), that information about the total current strength, with which the first sensor device (SEI) and the second sensor device (SE2) are operated, are supplied via a signal line of the comparator circuit (KS), wherein outputs (A1, A2, A3, A4) of the comparator circuit (KS) an evaluation logic (AL) are supplied, and wherein the evaluation logic (AL) is arranged such that it is determined in which operating state, the first and / or the second Sensor device (SE1, SE2) are located. Sensor system (SS) according to claim 1, wherein a sensor device (SE1, SE2) comprises a switching device, wherein the sensor device (SE1, SE2) executed in such a way is that the switching device depending on the operating condition the sensor device (SE1, SE2) is opened or closed. Sensor system (SS) according to one of the preceding claims, at the sensor devices (SE1, SE2) connected in parallel to each other are. Sensor system (SS) according to one of the preceding claims, at the comparator circuit (KS) at least four output signals (A1, A2, A3, A4) and in which the evaluation logic (AL) is set up in this way is that determined based on the output signals (A1, A2, A3, A4) In which operating state, the first and / or the second Sensor device (SE1, SE2) are located. Sensor system (SS) according to one of the preceding claims, at the at least one sensor device (SE1, SE2) a Hall sensor includes. Sensor system (SS) according to one of the preceding claims, at between the sensor devices (SE1, SE2) and the comparator circuit (KS) a conversion circuit is connected to the current, with the first sensor device (SE1) is operated, and the current, with the second sensor device (SE2) is operated, in a representative of the total amperage Total voltage signal that the comparator circuit (KS) supplied becomes. Sensor device (SE3) with two power supply inputs (E1, E2), which is set up in such a way that they operate over a first power supply input (E1) depending on their operating state is operated with a first or a second current, and that they over during operation a second power supply input (E2) depending operated by their operating state with a third or a fourth current becomes. Sensor device (SE3) according to claim 7 with a Switching device wherein the sensor device (SE3) is designed such that the switching device depending on the operating condition the sensor device (SE3) opened or closed.