Electricity: measuring and testing – Magnetic – Magnetometers
Reexamination Certificate
2002-05-23
2004-07-06
Le, N. (Department: 2862)
Electricity: measuring and testing
Magnetic
Magnetometers
C324S537000
Reexamination Certificate
active
06759844
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to a Hall sensor component with a Hall sensor through which an electric current flows and which sends a Hall signal, which depends on a magnetic field acting on the Hall sensor and the electric current, and a processing device arranged downstream of the Hall sensor for processing an input signal, which sends an output signal associated with the input signal.
BACKGROUND OF THE INVENTION
Hall sensors have been known from the prior art. They comprise, in principle, a conductive sensor surface, through which a current flows. If a magnetic field interacts with the sensor surface through which the current flows, the charged particles generated by the current are deflected on the basis of the Lorentz force, as a result of which an electric field is generated in the sensor surface, which is the cause for a voltage being present at lateral edges of the sensor surface. This voltage, which is called the Hall voltage, is proportional to the product of the magnetic flux density of the magnetic field and the current flowing through the sensor surface, so that the magnetic flux density can be determined by measuring the Hall voltage at a known current except for a proportionality factor, which depends, among other things, on the geometric dimensions of the sensor surface.
Hall sensors are available commercially, e.g., in the form of Hall sensor components, in which a processing device, which processes the Hall signal sent by the Hall sensor for an evaluation and sends a signal associated with the Hall signal as an output signal, is arranged downstream of the Hall sensor proper. Both the Hall sensor and the processing device are integrated in a single housing.
Hall sensor components are equipped with different processing devices for different possible applications. One possible application is, e.g., the determination of the magnetic flux density of the magnetic field acting on the Hall sensor by means of the Hall sensor component. The processing device is preferably designed for this purpose such that there is a linear dependence between the signal intensity of the output signal and the magnetic flux density in the broadest possible range.
Another possible application is the use of a Hall sensor component in conjunction with a magnet as a switching device subject to little friction loss, which can be switched into at least two switching states with a switch lever. A magnet, which is brought into the range of action of a Hall sensor component associated with the first switching state in a first switching state of the two switching states, is provided at the switch lever. The range of action is defined here as the area in space around the Hall sensor component, into which the magnet must be brought in order to bring about such an increase in the value of the Hall sensor that a first threshold value preset by the processing device will be exceeded. By setting this threshold value, it is thus possible to set the distance in space between the magnet and the Hall sensor provided in the Hall sensor component, below which distance the actual distance is to drop and at which the first switching state is considered to be switched on. Furthermore, a second threshold value, by which the distance in space between the magnet and the Hall sensor, which is to be exceeded and at which the first switching state is considered to be switched off, is preset by the processing device. The second threshold value may differ from the first threshold value, so that a so-called switching hysteresis is provided by the processing device. The processing device may be equipped, e.g., with a Schmitt trigger as a threshold value transducer to embody this switching hysteresis. The Hall sensor component may, of course, also be arranged at the switch lever in such low-friction switching devices. The Hall sensor component can be introduced in this case into the magnetic field of the magnet by moving the switch lever.
However, the more circuits are arranged downstream of the Hall sensor proper in the Hall sensor component, the greater is also the risk for failure of the Hall sensor component because of a defect in one of these circuits. If a prior-art Hall sensor component fails because of such a defect, the problem frequently arises that the ability of the Hall sensor component to function cannot be checked in the installed state or during operation, so that the defect is not recognized.
SUMMARY OF THE INVENTION
The basic object of the present invention is to provide a Hall sensor component in which the possibility of checking its ability to function is improved.
The Hall sensor component according to the present invention has a Hall sensor, through which an electric current flows, and a processing device for processing an input signal. The Hall sensor sends a Hall signal, which depends on a magnetic field acting on the Hall sensor and on the electric current. A processing device, which sends an output signal that is associated with and depends on the input signal, is arranged downstream of the Hall sensor. The Hall sensor and the processing device form one assembly unit, to which a diagnosis signal generated by a signal generator is sent. The Hall sensor is linked indirectly or directly with the diagnosis signal, and the Hall signal linked with the diagnosis signal is sent to the processing device as an input signal.
Since the Hall signal which is directly or indirectly linked with the diagnosis signal is sent according to the present invention to the processing device, the output signal is also affected by the diagnosis signal in a characteristic manner. However, two signal components, of which a first signal component characterizes the magnetic field and the second signal component characterizes the diagnosis signal, are thus derived according to the present invention from the output signal, the first signal component of the output signal being hereinafter called the magnetic component and the second signal component of the output signal being called the diagnosis component.
The diagnosis signal used may be any signal insofar as the diagnosis component and the magnetic component can be derived from the output signal. However, the diagnosis signal is preferably a periodic square wave signal.
The diagnosis signal can be sent to the Hall sensor in different ways. According to a first alternative, the Hall sensor may be directly linked with the diagnosis signal. The direct linking of the Hall signal and the diagnosis signal takes place only at or behind the output of the Hall sensor and may be embodied, e.g., by adding the Hall signal and the diagnosis signal by means of an analog adder to form a mixed signal, which will then form the input signal of the processing device.
However, according to a second alternative, the Hall signal may also be linked indirectly with the diagnosis signal by the electric current flowing through the Hall sensor being controlled as a function of the diagnosis signal.
If a periodic square wave signal, which alternatingly assumes a logic H (high) level and a logic L (low) level as a signal state, is sent to the Hall sensor in the case of the indirect linking of the Hall signal and the diagnosis signal, the current flowing through the Hall sensor is preferably switched on and off as a function of the signal state of the square wave signal. This means that the current is switched on when the square wave signal has a logic H level, and the current is switched off when the square wave signal has a logic L level or vice versa. The current flowing through the Hall sensor may be supplied by the signal generator.
The signal generator may be arranged outside the Hall sensor component, in which case the diagnosis signal is sent via a connection provided at the Hall sensor component. However, the signal generator is preferably integrated within the Hall sensor component.
If the processing device has a switching hysteresis with two threshold values regarding its input, and if the diagnosis signal is a periodic signal, the frequency of the diagnosis signal is pr
Aurora Reena
Le N.
McGlew and Tuttle , P.C.
ZF Lemförder Metallwaren AG
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