SENSOR DEVICE AND CIRCUIT MEANS AND METHOD FOR CONTROLLING THE ENERGY CONSUMPTION OF A SENSOR DEVICE

Abstract

An energy-efficient sensor device, a circuit arrangement for operating an energy-efficient sensor device, and a method for controlling the energy consumption of a sensor device. In particular, the operating mode of a sensor device is adapted as a function of a temporal change in a received sensor signal.

Claims

1. A circuit arrangement for automatically controlling the energy consumption of a sensor device, the circuit arrangement being part of the sensor device, and the circuit arrangement comprising: an analog front-end circuit including an analog-to-digital converter configured to read out an analog sensor signal detected by a sensor element and to convert the analog sensor signal into a digital sensor signal; a digital back-end circuit configured to process the digital sensor signal; at least one differentiating device configured to ascertain a temporal change in the sensor signal; and a control device configured to select and set one of multiple predefined operating modes of the sensor device as a function of the temporal change in the sensor signal.

2. The circuit arrangement as recited in claim 1, wherein the at least one differentiating device includes an analog differentiating device configured to 31 ascertain a temporal change in the analog sensor signal, the control device being configured to select and set one of multiple predefined operating modes of the sensor device as a function of the temporal change in the analog sensor signal.

3. The circuit arrangement as recited in claim 1, wherein the at least one differentiating device includes a digital differentiating device configured to ascertain a temporal change in the digital sensor signal, wherein the control device is configured to select and set one of the predefined operating modes of the sensor device as a function of the temporal change in the digital sensor signal.

4. The circuit arrangement as recited in claim 1, wherein at least one energy-saving mode, in which the sensor device is deactivated at least in part and/or at times, may be set as the operating mode of the sensor device.

5. The circuit arrangement as recited in claim 2, wherein at least one of the following energy-saving modes are settable as one of the predefined operating modes: cyclic operation of the sensor device, with components of the sensor device being activated and deactivated in an alternating manner in predefined, successive time intervals in cyclic operation; continuous operation of the analog differentiating device, of the control device, and of the analog front-end circuit, without the analog-to-digital converter, while the digital back-end circuit is deactivated; cyclic operation of the analog differentiating device, of the control device, and of the analog front-end circuit, without the analog-to-digital converter, while the digital back-end circuit is deactivated.

6. The circuit arrangement as recited in claim 1, wherein, in order to set one of the predefined operating modes of the sensor device, the control device is configured to: selectively activate and deactivate the analog-to-digital converter of the analog front-end circuit and at least parts of the digital back-end circuit; and/or vary a sampling rate at which the analog sensor signal is sampled during the conversion into a digital sensor signal, by actuating the analog-to-digital converter and/or a downstream filter of the analog front-end circuit; and/or vary time intervals of a cyclic operation of individual components of the sensor device; and/or maintain a continuous operation of individual components of the sensor device.

7. A sensor device, comprising: a sensor element for detecting a sensor signal, the sensor element including a micromechanical pressure sensor element, and/or an acceleration sensor element, and/or a rotation rate sensor element, and/or a magnetic sensor element; and a circuit arrangement configured to automatically controlling energy consumption of the sensor device, the circuit arrangement including: an analog front-end circuit including an analog-to-digital converter configured to read out an analog sensor signal detected by the sensor element and to convert the analog sensor signal into a digital sensor signal, a digital back-end circuit configured to process the digital sensor signal, at least one differentiating device configured to ascertain a temporal change in the sensor signal, and a control device configured to select and set one of multiple predefined operating modes of the sensor device as a function of the temporal change in the sensor signal.

8. A method for automatically controlling the energy consumption of a sensor device, the sensor device including at least one sensor element configured to detect an analog sensor signal, an analog front-end circuit with an analog-to-digital converter configured to read out the detected analog sensor signal and to convert the detected analog sensor signal into a digital sensor signal, a digital back-end circuit configured to process the digital sensor signal, and a control device configured to automatically set one of multiple predefined operating modes of the sensor device, the method comprising the following steps: continuously monitoring a temporal change in the sensor signal; and depending on the temporal change in the sensor signal, either maintaining a present operating mode or setting a different predefined operating mode.

9. The method as recited in claim 8, wherein the temporal change in the analog sensor signal is monitored, and when the sensor device is in an energy-saving mode in which the analog sensor signal is not being converted into a digital sensor signal and/or the temporal change in the digital sensor signal is not being determined, and a different operating mode is set only when the temporal change in the analog sensor signal exceeds a predefined threshold value for a predefined duration.

10. The method as recited in claim 9, wherein, when the sensor device is in the energy-saving mode and the temporal change in the analog sensor signal exceeds a predefined threshold value for a predefined duration, a different operating mode is set in which at least the analog-to-digital converter of the analog front-end circuit and a digital differentiating device for the digital sensor signal are activated at least at times.

11. The method as recited in claim 8, wherein the temporal change in the digital sensor signal is monitored, and when the sensor device is in an operating mode in which the analog sensor signal is being converted into a digital sensor signal and the temporal change in the digital sensor signal is being determined, a different operating mode is set only when the temporal change in the digital sensor signal exceeds or falls below a predefined threshold value for a predefined duration.

12. The method as recited in claim 11, wherein, when the temporal change in the digital sensor signal exceeds the predefined threshold value for the predefined duration, a different operating mode is set by: increasing a sampling rate at which the analog sensor signal is sampled during the conversion into the digital sensor signal, and/or varying a length of time intervals of a cyclic operation of individual components of the sensor device; and/or maintaining a continuous operation of at least individual components of the sensor device.

13. The method as recited in claim 11, wherein, when the temporal change in the digital sensor signal falls below the predefined threshold value for the predefined duration, a check is carried out as to whether an up-to-date level of the sensor signal corresponds to a level of the sensor signal in the energy-saving mode.

14. The method as recited in claim 13, wherein, wherein the up-to-date level of the sensor signal corresponds to the level of the sensor signal in the energy-saving mode, the energy-saving mode is set as the new operating mode.

15. The method as recited in claim 13, wherein, when the up-to-date level of the sensor signal does not correspond to the level of the sensor signal in the energy-saving mode, a different operating mode is set by: reducing a sampling rate of the sensor signal; and/or switching to a cyclic operation of individual components of the sensor device; and/or varying a length of time intervals of a cyclic operation of individual components of the sensor device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Further features and advantages of the present invention are explained below with reference to the figures.

[0019] FIG. 1 shows a block diagram of a sensor device including a circuit arrangement for automatically controlling the energy consumption according to one specific example embodiment of the present invention.

[0020] FIG. 2 shows a flowchart based on a method for automatically controlling the energy consumption of a sensor device according to one specific example embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0021] FIG. 1 shows a schematic illustration of a sensor device 100 according to one specific example embodiment of the present invention. Sensor device 100 includes at least one sensor 2 and circuit arrangement 1 for controlling the energy consumption of sensor device 100. Sensor 2 may be any arbitrary sensor which sensorially detects one or multiple parameters, such as for example temperature, pressure, humidity, brightness, speed, acceleration, or any arbitrary other parameter. For example, sensor 2 may be a micromechanical pressure sensor element, an acceleration sensor element, a rotation rate control sensor element, or a magnetic sensor element.

[0022] In the exemplary embodiment shown here, the parameter is detected capacitively and is converted into an analog sensor signal by a capacitance/voltage converter 10. However, any arbitrary other way of providing the analog sensor signal is of course also possible.

[0023] Circuit arrangement 1 include an analog front-end circuit 30. Capacitance/voltage converter 10 is part of this analog front-end circuit 30, which further includes an analog-to-digital converter 32 with variable sampling rate and resolution. By way of this analog-to-digital converter 32, the analog sensor signal is converted into a digital sensor signal.

[0024] Further processing of the digitized sensor signal may take place for example in a digital back-end circuit 40, which is likewise part of circuit arrangement 1. For example, digital back-end circuit 40 may include any arbitrary suitable components, such as for example a digital filter 43 including variable filter parameters which is arranged downstream of analog-to-digital converter 32. Any additional arbitrary components, such as for example an amplifier, a first-in first-out (FIFO) memory or an output interface, are of course possible. In particular, the processed sensor signal may be transferred to one or multiple further devices via a wired or wireless interface. The transfer may in this case take place using any arbitrary suitable format or protocol.

[0025] According to the example embodiment of the present invention, circuit arrangment 1 include at least one differentiating device 31, 41 that monitors the analog and/or the digitized sensor signal and detects a temporal change in the sensor signal. In the exemplary embodiment shown here, an analog differentiating device 31 is provided, which monitors the analog sensor signal provided by capacitance/voltage converter 10 and detects a change in the analog sensor signal, for example a deviation of the sensor signal by more than a predefined threshold value or a change in the sensor signal by more than a predefined value within a predetermined period of time. Here, a digital differentiating device 41 is additionally provided in digital back-end circuit 40, which detects a change in the digitized sensor signal.

[0026] The deviation determined by analog differentiating device 31 and/or digital differentiating device 41, in particular the deviation of the sensor signal over time, is provided to a control device 42 that is designed to select and set one of multiple predefined operating modes of sensor device 100 as a function of the temporal change in the sensor signal. For this purpose, control device 42 may vary the operation of individual components of sensor device 100, in particular the operating mode of analog-to-digital converter 32 and/or of filter 43, in particular in digital back-end circuit 40 as a function of the ascertained change in the sensor signal.

[0027] For example, control device 42 may put the corresponding components of sensor device 100 into a sleep mode if the analog sensor signal does not change or at least does not change significantly. For example, control device 42 may put analog-to-digital converter 32 and/or components 41 and 43 in digital back-end circuit 40 into the sleep mode for as long as the analog sensor signal does not change by more than a predefined threshold value. Alternatively, the corresponding components may also remain in the sleep mode for as long as the analog sensor signal does not change by more than a predefined threshold value within a predefined period of time. Any other criteria for maintaining the sleep mode or setting the sleep mode are of course also possible.

[0028] If a predetermined event is detected on the basis of the monitoring by at least one of differentiating devices 31, 41, for example a deviation of the sensor signal by more than a predetermined value or a deviation of the sensor signal by more than a predetermined value within a predetermined period of time, control device 42 selects a different predefined operating mode for sensor device 100 and initiates the switch to this different operating mode. For this purpose, control device 42 may for example activate analog-to-digital converter 32 and/or the necessary further components to carry out any arbitrary operations, such as for example an analog-to-digital conversion, filtering, storing, data transfer or the like.

[0029] To further optimize the operating behavior of sensor device 100, in particular to optimize the energy consumption, it is additionally also possible to dynamically adapt one or multiple settings of the components of sensor device 100, such as for example of analog-to-digital converter 32. For example, a clock rate for processing the digitized sensor data within sensor device 100, in particular in digital back-end circuit 40, may be adapted as a function of the change in the sensor signal determined by analog and/or digital differentiating device 31, 41. For example, the data may be processed at a higher processing rate if a rapid change in the sensor signal has been detected by differentiating devices 31, 41. Conversely, the processing rate may be reduced if differentiating devices 31, 41 have detected that the sensor signal is changing only slowly.

[0030] In addition or as an alternative, it is also possible for example to adapt operating parameters, such as for example a sampling rate of an analog-to-digital converter 32, as a function of the rate of change in the sensor signal. For example, the sampling rate of analog-to-digital converter 32 may be increased if analog and/or digital differentiating device 31, 41 establishes that the sensor signal at input terminal 10 is changing rapidly. Analogously, the sampling rate of analog-to-digital converter 32 may be reduced if the sensor signal is changing more slowly. Of course, any other arbitrary parameters that may be dynamically adapted as a function of the temporal change in the sensor signal at input terminal 10 are also possible.

[0031] If the analog sensor signal is not changing or at least is not changing significantly, then optionally analog-to-digital converter 32 and/or further components of sensor device 100, in particular of digital back-end circuit 40, may be put into the sleep mode. In this sleep mode, for example, the processing of the sensor data may then be limited or optionally even abandoned entirely. For example, it is possible that no processing of sensor data takes place during the sleep mode. Alternatively, it is also possible for example that a limited processing of sensor signals takes place in a sleep mode. For example, an optional brief processing of sensor signals may take place cyclically even in the sleep mode. For example, a processing of the sensor signals may take place for a predetermined period of time. The processing of the sensor signals may subsequently be paused for a further period of time, in order to process the sensor signals thereafter again for a predetermined period of time. In this way, an at least limited further processing of the sensor signals may take place even in the case of constant sensor signals or sensor signals that are changing only a little.

[0032] FIG. 2 shows a flowchart based on a method for controlling the energy consumption of a sensor device 100 according to one specific example embodiment of the present invention. The method may include any arbitrary steps as already described above in connection with sensor device 100. Analogously, sensor device 100 may also include any arbitrary components suitable for implementing the method described below.

[0033] The method may in particular be applied to a sensor device 100 including a sensor element 2, an analog front-end circuit 30, and a digital back-end circuit 40.

[0034] At the start, in step Sl, the method may initially be in a state of particularly low energy consumption (Ultra Low Power, ULP). For example, all components apart from input interface 10 may be deactivated. As the method continues, for example in step S2, an analog differentiating device 31 may be activated to check an input signal for a possible temporal change. Here, analog differentiating device 31 may be operated for example in continuous operation over a relatively long period of time. Alternatively, it is also possible that analog differentiating device 31 is activated only cyclically for predetermined time intervals in each case, and then is deactivated thereafter for further predetermined time intervals in each case.

[0035] In step S3, a check may be carried out as to whether the magnitude of a temporal change delta_a in the received analog signal exceeds a predefined threshold value S_a. If the magnitude of the temporal change delta_a is less than the predefined threshold value S_a, the components of sensor device 100 remain in their up-to-date state. Otherwise, if the magnitude delta_a of the temporal change in the analog input signal exceeds the predefined threshold value S_a, further components of sensor device 100 may be activated in step S4. For example, an analog-to-digital converter 32 of analog front-end circuit 30 may be activated. Furthermore, components of digital back-end circuit 40 may also be activated.

[0036] In step S5, with back-end circuit 40 activated, a temporal change in the received sensor signal may be monitored in the digital domain by a digital differentiating device 41. If it is established in step S6 that the temporal change in the digitized sensor signal is approximately constant, the system may maintain its present operating state. Otherwise, a check may be carried out in step S7 as to whether the temporal change in the received sensor signal has increased or decreased.

[0037] If it is established in step S7 that the temporal change in the sensor signal is increasing further, the operation of the components in sensor device 100, in particular in analog-to-digital converter 32 or in digital back-end circuit 40, may be adapted accordingly for example in step S8. For example, a sampling rate for the analog-to-digital conversion in analog-to-digital converter 32 may be increased. If some components, for example components of digital back-end circuit 40, are being operated in a cyclic operation, the duty cycle of the cyclic operation may be adapted if it is detected that the temporal change in the sensor signal is increasing. For example, the pauses between two active operating periods may be shortened. Furthermore, a switch from cyclic operation to continuous operation may also take place for example.

[0038] If, in contrast, it is established in step S7 that the temporal change in the sensor signal is decreasing compared to the previous point in time, then initially a check may be carried out in step S9 as to whether an active operation of sensor device 100 is still necessary. If, for example, it is established in step S7 that the temporal change in the received sensor signal has fallen below a corresponding threshold value or other criteria are met (and the amplitude of the received sensor signal has fallen below a predefined threshold value), thereby justifying an at least partial deactivation of sensor device 100, sensor device 100 may be switched to the ultra low power mode described above.

[0039] If, in contrast, it is established in step S9 that the temporal change in the received sensor signal has decreased only a little, the operating mode of sensor device 100 may be adapted accordingly. For example, in step S10, a sampling rate of analog-to-digital converter 32 may be reduced. If all or at least some of the components of sensor device 100 are in a continuous operating mode, then in step S10 the continuous operating mode may optionally also be switched to a cyclic operating mode, in which at least some of the components are activated only temporarily and are thereafter deactivated for a predetermined period of time. If at least some of the components of sensor device 100 are already being operated in a cyclic operating mode, the operating parameters of this cyclic operation may optionally also be adapted. For example, the pauses between two active phases may be increased, or the operating duration of the active phases may be shortened.

[0040] In summary, the present invention relates to an energy-efficient sensor device, to a circuit arrangement for operating an energy-efficient sensor device, and to a method for controlling the energy consumption of a sensor device. In particular, the operating mode of a sensor device is adapted as a function of a temporal change in a received sensor signal.