Frequency generator assembly

This application is the U.S. National Phase Application of PCT International Application No. PCT/EP2012/074999, filed Dec. 10, 2012, which claims priority to German Patent Application No. 10 2011 089 813.1, filed Dec. 23, 2011, the contents of such applications being incorporated by reference herein.

The invention relates to a frequency generator assembly according to the precharacterizing clause of claim 1 and to the use of the frequency generator assembly in motor vehicles.

It is known practice to use controlled crystal oscillators as frequency generator assemblies for generating an electrical clock signal.

An aspect of the invention proposes a frequency generator assembly which does not resort to such a relatively expensive crystal oscillator.

A sensor element which comprises the at least one micromechanical seismic mass of the oscillator is preferably understood as meaning an inertial sensor element; this sensor element is in the form of a rate-of-rotation sensor element, in particular.

The entire oscillator is preferably in the form of a micromechanical rate-of-rotation sensor element and the at least one seismic mass is designed and operated in such a manner that it is designed both to record a rate of rotation about at least one axis and, in particular simultaneously, is in the form of a seismic mass of the oscillator of the frequency generator assembly, in which case the electrical clock signal is generated or influenced on the basis of the oscillation frequency of this at least one seismic mass.

A clock signal is preferably understood as meaning an electrical binary signal, the alternating frequency of which is designed to be substantially constant, in particular, or alternatively is preferably designed to be changing or aperiodic.

The frequency generator assembly preferably comprises a control unit which is designed in such a manner that the oscillation of the at least one seismic mass of the oscillator is adjusted to a defined frequency value, in particular its natural frequency.

The oscillator preferably comprises a drive device which drives the at least one seismic mass or excites it to oscillate or influences the oscillation of the seismic mass, and a reading device which records the deflection of the at least one seismic mass with respect to the at least one oscillation mode. The drive device and the reading device are particularly preferably designed according to the electrostatic operating principle.

The oscillator and its at least one seismic mass, in particular its two seismic masses, are expediently designed and operated in such a manner that they are in the form of a micromechanical rate-of-rotation sensor element for a drive mode and a reading mode with respect to the design of the oscillator. In this case, the frequency generator assembly is particularly preferably designed in such a manner that the electrical clock signal is generated on the basis of the oscillation or oscillation frequency of the at least one seismic mass in its drive mode.

The frequency generator assembly is preferably designed in such a manner that the electrical clock signal is generated or influenced by a frequency multiplication unit. A frequency multiplication unit is understood as meaning, in particular, a unit for frequency conversion which particularly preferably need not have an integer form.

The frequency generator assembly preferably has a temperature sensor which is designed in such a manner that it directly or indirectly records the temperature of at least the oscillator in the environment/vicinity of the oscillator. In particular, the temperature sensor is linked in this case to the frequency multiplication unit via a calibration unit or interacts with such a calibration unit, and the frequency generator assembly is designed in such a manner that the frequency of the clock signal is set independently of the temperature of the oscillator and particularly preferably independently of the temperature dependence of the natural frequency of the oscillator.

The temperature sensor is expediently arranged in the signal processing device, in particular in the control unit in this case. The signal processing device or the control unit is particularly preferably connected and/or coupled to the oscillator in this case in a thermally conductive manner.

It is preferred for the frequency generator assembly to be connected to an external circuit unit comprising at least one microprocessor and to provide this circuit unit with the clock signal.

It is expedient that the external circuit unit is in the form of an external microcontroller, and this microcontroller is at least partially operated in a clocked manner by means of the clock signal from the frequency generator assembly.

It is preferred for the external circuit unit and the frequency generator assembly to belong to a sensor cluster or to form parts of a sensor cluster and, in particular, to have a common housing. In this case, this sensor cluster particularly preferably comprises at least one rate-of-rotation sensor element and at least one acceleration sensor element.

An aspect of the invention also relates to the use of the frequency generator assembly in motor vehicles, in particular for providing the clock signal for at least one external microcontroller and/or an external sensor assembly.

Further preferred embodiments emerge from the subclaims and the following description of an exemplary embodiment using a FIGURE.

FIG. 1 shows, in a schematic illustration, an exemplary frequency generator assembly comprising an oscillator 1 which is also in the form of a rate-of-rotation sensor element and is simultaneously used as such. A seismic mass 11 is excited to oscillate by means of the drive device 12 , the frequency of which oscillation is adjusted to the natural frequency of the seismic mass by the control unit 23 . The oscillator has a reading device 13 for this control circuit and for recording the deflections of the drive mode of the seismic mass 11 of the oscillator 1 . This reading device 13 or oscillator 1 is connected to a signal processing device 2 which has a frequency multiplication unit 21 so that an electrical clock signal can be generated at a desired, defined frequency f on the basis of the regular oscillation frequency of the seismic mass. The frequency generator assembly also comprises a temperature sensor 3 which records the temperature of the oscillator 1 and provides a calibration unit 22 of the signal processing device 2 with this temperature information, as a result of which the clock signal f is generated independently of the temperature or in a temperature-compensated manner. In this case, the temperature sensor 3 is integrated in the control unit 23 , for example, and is thermally coupled to the oscillator 1 .

This clock signal f is made available to an external microcontroller 4 , this microcontroller being operated in a clocked manner on the basis of this clock signal f or using this clock signal.