Sensor device for detecting a physical variable acting on the sensor device

Abstract

The invention relates to a sensor device (10) for detecting a physical variable (110) acting on the sensor device (10), in particular an ambient pressure acting on the sensor device (10), wherein the sensor device (10) has a sensor unit (11) which operates according to an optical measurement principle, and the sensor device (10) is designed to detect the physical variable (110) by means of the sensor unit (11) and to detect a movement of the sensor device (10), the movement being carried out in particular during the detection of the physical variable (110), and / or to at least partly compensate for an influence of the movement on the detection of the physical variable (110).

Description

[0001] R. 416383

[0002] - 1 -

[0003] Description

[0004] Sensor device for detecting a physical quantity acting on the sensor device

[0005] State of the art

[0006] Over the years, consumer electronics products such as mobile phones and smartwatches have become increasingly powerful and integrated more and more functions. This has been made possible by the inclusion of more and better sensors in these products to detect their own condition or the surrounding environment. A concrete example of such a sensor is the pressure sensor, which is now found in many consumer electronics products. Pressure sensors enable, for example, weather predictions by deriving weather changes based on the measured air pressure. Pressure sensors also allow for the determination of altitude changes, such as for tracking hikes or changes of floor in buildings where there may be no or only a weak GPS signal.One particular application is the automatic emergency call system, where the exact location of a fallen user is automatically transmitted to an emergency call center. A pressure sensor can be used to determine the floor on which the emergency occurred. The pressure sensor can also be used for fall detection itself, possibly in combination with an accelerometer.

[0007] Sensors can be based on different measurement principles, each with its own characteristic advantages and disadvantages. In the case of pressure sensors, a piezoresistive or capacitive measurement principle is classically used. A typical implementation of a piezoresistive pressure sensor is characterized by the fact that, compared to a capacitive pressure sensor, it can be operated more easily over a wide pressure range; however, a piezoresistive pressure sensor is comparatively susceptible to thermal effects. R. 416383

[0008] - 2 -

[0009] A typical implementation of a capacitive pressure sensor has low noise and low power consumption compared to a pressure sensor with a different measurement principle, but it is optimized for a specific operating point. A disadvantage of capacitive pressure sensors is their susceptibility to parasitic capacitances, which can interfere with the measurement signal.

[0010] In summary, both capacitive and piezoresistive pressure sensors have disadvantages that hinder their widespread and flexible use in consumer electronics.

[0011] Optical devices can be used to measure rotations or rotational speeds. This can be done, for example, using a fiber-optic gyroscope (IFOG) or a Sagnac interferometer.

[0012] However, the effect exploited by these optical arrangements means that many implementations of optical sensors, especially optical pressure sensors, are affected by spatial changes in the sensor device, particularly its rotation (and its derivatives such as rotational speed, rotational acceleration, and so on). In the case of sensors, this effect is considered a disturbance, as it can superimpose and thus distort the relevant output signal, e.g., the current applied pressure in the case of a pressure sensor.

[0013] The invention aims to solve, or at least reduce or optimize, the aforementioned problems in the prior art.

[0014] Disclosure of the invention

[0015] The invention relates to a sensor device for detecting a physical quantity acting on the sensor device, in particular an ambient pressure of the sensor device, wherein the sensor device comprises a sensor unit with an optical measuring principle, and wherein the sensor device is configured to detect the physical quantity by means of the sensor unit and to detect a movement of the sensor device, in particular during the detection of the physical quantity. R. 416383

[0016] - 3 - and / or to at least partially compensate for the influence of movement on the measurement of the physical quantity.

[0017] An advantage of this is that, due to its optical measuring principle, the sensor device is less susceptible to thermal effects or parasitic capacitances compared to prior art sensor devices with a different measuring principle. This allows the sensor device according to the invention to be used in a very wide range of consumer electronics products.

[0018] Furthermore, a reduction or elimination of interference caused by the movement of the sensor device can be achieved, resulting in a more robust and higher-performing sensor device. If movement is detected, the sensor device or a higher-level system, such as a mobile phone or smartwatch, can actively compensate for the disruptive influence of the movement on the measurement of the physical quantity, particularly by means of a suitable processing unit. Alternatively or additionally, the sensor device can be designed in such a way that the influence of the movement is passively compensated for during the measurement of the physical quantity.

[0019] The sensor unit can be designed, for example, as a pressure sensor. However, other sensor types are also conceivable, such as an environmental sensor, inertial sensor, gyroscope, accelerometer, magnetic sensor, humidity sensor, temperature sensor, gas sensor, particulate matter sensor, or microphone. The sensor unit uses an optical measurement principle to detect the physical quantity. This physical quantity could, for example, represent the ambient pressure of the sensor device. Depending on the sensor type, however, the physical quantity could also be, for example, acceleration, rotational speed, a magnetic field, humidity, temperature, sound, or material composition, each acting on the sensor device and the sensor unit it contains.

[0020] An optical measuring principle uses light to measure a physical quantity. Changes in the properties of light (e.g., intensity, phase, polarization, R. 416383)

[0021] - 4 -

[0022] Wavelength or frequency) caused by a change in the physical quantity is detected and converted into a measurable signal.

[0023] Motion refers to a spatial change of the sensor device over time. A sensor device's movement manifests itself particularly through a change in its position, orientation, or shape within three-dimensional space. Examples of motion include acceleration, rotation, or deformation.

[0024] The movement of the sensor device includes, in particular, at least an indirect spatial change of the sensor unit.

[0025] Compensation refers to the balancing or elimination of an undesirable quantity or effect. This compensation can be passive, whereby the sensor device is designed in such a way that the measurement signal captured by the sensor unit is not affected at all, or only minimally, by the movement of the sensor device. Alternatively, or additionally, compensation can be active, whereby the sensor device subsequently corrects the measurement signal captured by the sensor unit, depending on the detected movement. This compensation can be performed directly by the sensor device or externally, particularly in a higher-level system such as a smartwatch, mobile phone, or headphones.

[0026] In particular, the sensor device may, in addition to the actual sensor unit, also include a temperature sensor unit which can be used by the sensor device for thermal compensation.

[0027] In particular, the sensor device may have a housing, wherein at least the sensor unit is arranged inside the housing.

[0028] The housing is typically a rigid casing that protects the sensor unit and other components located within it from negative external influences. Such negative influences can include, for example, unintentional mechanical shocks, moisture, or contamination. The arrangement R. 416383

[0029] - 5 - the sensor unit and the other components within the housing, that the sensor unit and the other components are arranged in a receiving space formed by the housing. Another advantage of a sensor device with a housing is that it results in an encapsulated sensor module that can be easily integrated as a component.

[0030] In particular, the housing can comprise a printed circuit board on which the sensor device components are arranged, and a surrounding side wall and / or potting compound around the sensor device components. Optionally, the housing can also include a cover. The components located inside the housing typically have solder pads for electrical contact. Bond connections, for example, can be used for electrical contact between the components.

[0031] Furthermore, the housing may have a through-opening from the interior of the housing to the environment of the sensor device. In particular, the sensor unit is positioned within the housing in such a way that it can interact with the surrounding environment. This is necessary, for example, for pressure sensors. These require an opening towards the one or two environments of the sensor device whose pressure is to be determined. Accordingly, the housing is designed to allow the pressure sensor module to be installed in such a way that the detection diaphragm of the sensor unit can be influenced as directly as possible by the ambient pressure. The environment of the sensor device can be understood as everything outside the housing. This direct contact with the environment makes pressure sensors susceptible to contamination such as deposits of solids (dust, particles, evaporation residues, production residues, etc.).) or liquids (water, chemicals, condensation), so that the pressure-sensitive membrane of the sensor unit or other components of the sensor device located within the housing are often protected from these environmental effects by protective mechanisms. This can be achieved by a gel-like, protective, but pressure-permeable protective layer or by an additional air-permeable protective membrane or an air filter R. 416383.

[0032] - 6 - The protective layer can be used in particular if no lid element is present.

[0033] In particular, the housing may also have a sealing element which serves to seal against a higher-level system such as a mobile phone or a smartwatch.

[0034] One embodiment of the invention provides that the sensor device comprises a processing unit and that the sensor unit comprises an optical source, an optical detector, and a sensor element, wherein the processing unit is configured to emit a light beam by means of the optical source within an optical path to the optical detector, wherein the sensor element at least partially encompasses the optical path and is configured such that, in the event of at least partial deformation and / or at least partial deflection and / or at least partial change of a physical property of the sensor element, which occurs in particular due to a change in the physical quantity to be measured by the sensor device, the optical path changes at least partially, and wherein the processing unit is configured toThe optical detector is used to detect changes in the light beam passing through the optical path and to determine the physical quantity based on these changes.

[0035] The advantage here is that the physical quantity can be determined quickly and reliably using the sensor unit.

[0036] The processing unit can be implemented as an application-specific integrated circuit (ASIC), which may include a microcontroller. Among other things, the processing unit controls the optical source and evaluates the output signals acquired by the optical detector, providing information about the light beam. Based on this information, the physical quantity can be determined.

[0037] Oversampling can occur during the acquisition of the measured values, so that several individual measurements are combined into a common output signal R. 416383

[0038] - 7 - are combined or averaged to reduce the noise of the output signals.

[0039] Furthermore, the processing unit can be set up to implement a FIFO (First In, First Out) principle for measurement acquisition and storage, in which output signals received in a free-running mode are filled into the FIFO memory in order to decouple the time of measurement from the readout by the user.

[0040] Furthermore, the processing unit can be configured to perform additional steps after measurement acquisition to appropriately condition the measurement signal. This can include, for example, compensation for sensor-specific behavior, nonlinearities, and / or temperature and / or humidity effects. In particular, the sensor device can have an integrated temperature sensor unit and / or humidity sensor unit for this purpose.

[0041] Furthermore, the processing unit can be configured to perform a

[0042] To trigger an interrupt when a configurable condition is met. This can include power-on reset, new measurement signals, reaching a specific FIFO fill level, complete filling of the FIFO memory, exceeding a predefined or relative output signal value, or exceeding a certain output signal value change.

[0043] In particular, the processing unit can be integrated into the sensor unit or arranged externally from the sensor unit, for example to be used by other sensor units.

[0044] In particular, the sensor device is designed such that a change in the physical quantity in the environment of the sensor device causes at least a partial deformation and / or at least a partial deflection and / or at least a partial change in a physical property of the sensor element of the sensor unit. The physical quantity in question is, in particular, ambient pressure, whereby a pressure change can be measured by means of the sensor unit.

[0045] Deformation refers to a change in the shape and / or size of a body under the influence of external forces or other effects, such as changes in stress, temperature, or pressure. The relative R. 416383

[0046] - 8 -

[0047] The positions of the particles within the body change. In particular, deformation can refer to the change in the shape of the sensor element's membrane under the influence of the pressure being measured. This deformation, which is typically elastic, leads to a change in the optical path, thus enabling pressure measurement. The deformation can encompass various types, such as bending, stretching, compression, or torsion. The precise type of deformation depends on the membrane's geometry, its mounting, the material, and the magnitude and orientation of the applied force. Displacement describes the deviation of a body or body part from its equilibrium position or a defined reference position. It is a vector that specifies both the magnitude and direction of the deviation.Unlike deformation, which describes a change in shape, displacement refers to a change in the position of a body or body part without necessarily altering its shape. Of course, displacement can also occur in conjunction with deformation, but this is not always the case.

[0048] A physical property is a measurable characteristic of a physical system that can be determined without altering its chemical composition. It describes the state or behavior of a system under specific conditions. Examples of physical properties include temperature, density, polarization, transparency, refractive index, and volume. If the density of the material in the sensor element changes, the refractive index typically also changes. This affects the propagation of light along the optical path and can, for example, cause a phase shift in the light beam. Deformation of the membrane can also affect the reflectivity of the sensor element. This alters the intensity of the reflected light and can thus be detected. Similar to reflectivity, transmission—the proportion of light that passes through the optical path—can also be affected by deformation.

[0049] In particular, the sensor element is designed as a MEMS (microelectromechanical system) component. R. 416383

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[0051] The optical source, for example, is designed as a thermal radiator, laser, or light-emitting diode (LED) and serves to emit a beam of light. The laser can be edge-emitting or surface-emitting. The LED can be made of semiconductor material or organic materials, for example.

[0052] Here, a light ray can be understood as a narrow bundle of light waves propagating in a specific direction. The wavefronts of the light, i.e., the surfaces of equal phase, are perpendicular to the direction of propagation of the ray. Due to diffraction and other wave effects, a light ray spreads out with increasing distance. Furthermore, the intensity of the light is not uniformly distributed across the cross-section of the ray, but typically has a maximum in the center and decreases towards the edges (e.g., Gaussian intensity distribution).

[0053] The optical source can be arranged within the housing, in particular essentially integrated into the sensor element, and the light beam can be coupled into the optical path, in particular by means of a grating coupler and / or a taper. The optical source can be arranged above, below, or next to the sensor element, or integrated within the sensor element.

[0054] The light beam emitted by the optical source has, for example, a wavelength in the ultraviolet wavelength range (100 to 400 nm), in the optical range (400 to 780 nm) or in the infrared range (780 to 3000 nm), in particular within the 850 nm band, the O-band (“original”, 1260 to 1360 nm), the E-band (“extended”, 1360 to 1460 nm), the S-band (“short”, 1460 to 1530 nm), the C-band (“conventional”, 1530 to 1565 nm) or the L-band (“long”, 1565 to 1625 nm).

[0055] A grating coupler is an optical element that couples light between different waveguides or between a waveguide and a free-space beam. It consists of a periodic structure (the grating) on ​​or near the waveguide. The grating diffracts the light, thus enabling the transition between the different modes. Grating couplers are often used to couple light into an optical chip or to distribute light between different areas of a chip. In particular, a grating coupler can be used to couple light from the source into the waveguide. R. 416383

[0056] - 10 - of the sensor element. A taper is a tapered waveguide whose cross-section gradually changes. It serves to couple light between waveguides with different cross-sections or between a waveguide and a free-space beam. The gradual change in cross-section minimizes reflections and achieves efficient coupling. In particular, a taper can be used to couple light from the source into the waveguide of the sensor element and / or to focus the light beam onto the diaphragm within the sensor element.

[0057] The optical detector is designed, for example, as a photodiode and serves to detect the light beam captured by the optical source.

[0058] The light beam travels along an optical path that passes at least partially through the sensor element. The sensor element is designed to respond to the physical quantity in such a way that a change in this physical quantity affects the optical path at least partially encompassed by the sensor element, which in turn alters the light beam traveling along the optical path. This change in the light beam can be detected by the optical detector.

[0059] The change in the light beam can include a phase shift, a change in intensity distribution, and / or a change in amplitude. This change can be caused by the action of the physical quantity on the sensor element and, consequently, on the optical path. In the context of optical sensors, the intensity distribution typically refers to the distribution of light intensity across the cross-section of the light beam. A typical light beam, for example, would have a Gaussian intensity distribution, meaning the intensity of the light beam is highest at its center and decreases towards the edges.If the physical quantity causes a deformation of the sensor element and the optical path it encompasses, the intensity distribution of the light beam can change accordingly. The measurement of the light beam by the optical detector and the information it contains about the intensity distribution, in turn, allow conclusions to be drawn about the change in the physical quantity. R. 416383.

[0060] - 11 -

[0061] In particular, changing the optical path, for example by changing the effective refractive index, can have an influence on the phase or amplitude of the light ray passing through the optical path.

[0062] In particular, the optical detector can have one or more measuring elements, wherein multiple measuring elements are arranged along a straight line, as a two-dimensional array, or as a three-dimensional arrangement, and wherein the measuring elements are oriented radially and / or orthogonally to the light beam emanating from the optical source. If multiple measuring elements are used, a differential measurement can be performed, which is more robust and precise than a single measurement. In the simplest case, a change in the intensity of the light beam can be measured with a single measuring element. However, an arrangement of at least two measuring elements is often more advantageous. For example, the light that is mixed in a multimode interferometer with two outputs can be detected with two measuring elements.If one measuring element detects a higher intensity, the measured intensity at the other measuring element decreases, thus implementing a differential measurement principle. In the subsequent signal processing, the measured signals of the two measuring elements are preferably subtracted from each other.

[0063] Even more measuring elements can be used to fully exploit the principle. For example, when using frequency combs, these can be divided according to frequency using a wavelength demultiplexer. This allows each frequency to be measured on its own measuring element, and the resulting signals can then be combined.

[0064] In particular, the optical source and the optical detector can be designed as a surface emitter with an integrated photodiode. This enables a convenient combination of optical source and optical detector in a single element, thereby saving space, complexity, and / or costs, as well as achieving better performance of the sensor device. This concept can utilize self-mixing interference (SMI) and allows precise measurements of R. 416383.

[0065] - 12 -

[0066] Speeds and distances, especially of the pressure-sensitive measuring membrane.

[0067] The sensor element can comprise a membrane that is at least partially free, wherein the membrane is deformable and / or deflectable, for example, by a pressure change acting on the membrane, and wherein the membrane is at least partially adjacent to and / or encompasses the optical path.

[0068] Due to its isolation, the membrane can move or deform when the ambient pressure changes, thus affecting the optical path. For this purpose, the membrane is positioned between two volumes, deforming according to the pressure ratio between the two volumes.

[0069] A membrane is a thin, planar structure that separates two spaces and is typically flexible and / or elastic. It can be made of various materials, such as plastics, metals, ceramics, or even biological tissue. In particular, a membrane often incorporates a semiconductor material. It is typically impermeable to air, so pressure differences cause deformation that does not reverse through diffusion. "Free" in this context means that the membrane is at least partially unsupported or unfixed by other structures and is therefore freely movable. For example, the membrane might only be attached at its edges or at specific points, while the central area is free to move. It is essentially "cut out" or "detached" and can deform or deflect under the influence of forces, in this case, pressure.The attachment points serve to position and hold the membrane, but still allow sufficient movement for pressure measurement.

[0070] The optical path can, in particular, comprise an optical waveguide whose optical properties, such as dispersion or effective refractive index, and / or shape are variable due to external influence. The optical path is transparent to wavelengths of the optical source, allowing the light beam to propagate within it. The waveguide can be implemented in various ways, as shown in R. 416383.

[0071] - 13 - for example, web, slot, ribbed waveguides or similar, as well as combinations thereof. Web waveguides are easy to design and manufacture. Slotted waveguides can achieve increased sensitivity due to a more focused light field. Ribbed waveguides have the advantage of lower loss, allowing for a longer sensor area. Multiple waveguides or optical paths, as well as other optical components such as mirrors, optical splitters, or optical combiners, can also be used.

[0072] Furthermore, the sensor element can have a cavity, with the membrane spanning the cavity. Alternatively or additionally, the sensor device can be designed such that a first pressure from a first region of the sensor device's environment acts on the top side of the membrane, and a second pressure from a second region of the sensor device's environment acts on the underside of the membrane. Accordingly, the sensor device can be designed as an absolute pressure sensor or as a differential pressure sensor.

[0073] A cavity is a void within the sensor element. The cavity serves to create a defined space within the sensor element, which is spanned by the membrane.

[0074] In particular, the cavity can be hermetically sealed to enable an absolute pressure sensor. In absolute pressure sensors, one volume is formed by the environment whose pressure is to be detected, while the other volume is formed by a sealed cavity with near-vacuum within the sensor element. Alternatively, the cavity has another opening to a further region of the sensor device's environment to function as a differential pressure sensor. An alternative embodiment of the sensor element as a differential pressure sensor does not have a cavity, but rather a free-standing membrane that is connected on both sides to the corresponding environments of the sensor device.

[0075] In particular, the membrane features a T-shaped element extending from the membrane into the cavity. This allows, among other things, more precise adjustment of the membrane's sensitivity or stiffness (through the stiffening element) and a less non-linear response. 416383

[0076] - 14 -

[0077] The behavior of the sensor in response to pressure changes (through the plate) is affected. A simple diaphragm of an absolute pressure sensor flexes, causing the distances to a counter surface to vary across the diaphragm area and, in particular, to change by varying degrees. Integrating a T-shaped element into the diaphragm ensures uniform movement of the diaphragm even under larger pressure changes and improves the linearity of the sensor. This is achieved because the plate of the T-shaped element and the counter surface of the cavity always remain parallel, and the distance changes uniformly across the entire diaphragm area.

[0078] The T-shaped element, for example, is formed from a stem-shaped stiffening element and a plate element placed on top of it, with the stiffening element being arranged between the plate element and the actual membrane surface.

[0079] A measurement to capture a physical quantity can proceed as follows. A trigger signal, such as user input or an automatic trigger (e.g., within a free-running mode), initiates a measurement. This can also include preparatory measures not explicitly listed, such as setting parameters, activating power domains, updating internal state machines, and similar actions. In the next step, the optical source is activated, and the resulting light beam interacts with the optical path of the sensor element, which is acting upon the physical quantity. The light beam is then captured by the optical detector and typically converted into an electrical signal. To conserve energy, the optical source should optionally be deactivated after signal acquisition is complete.Subsequently, the information acquired by the optical detector is processed. This can include conversion to a digital signal, but also downstream processing steps such as compensation of the measurement signal for temperature effects or nonlinearities, as well as oversampling steps or, in particular, digital filtering. Feedback effects may occur, for example, between the detector and the source, signal processing and the source, and / or the end of the measurement and R. 416383.

[0080] - 15 - the beginning, for example by setting new triggers for a connection measurement.

[0081] The information from the light beam is then used to determine the physical quantity.

[0082] In particular, the processing unit can be configured to activate the optical source and / or the optical detector only during a measurement process. This results in lower energy consumption for the sensor device, as the corresponding components are only used when needed. Furthermore, this can also extend the sensor device's lifespan. These advantages are particularly relevant when using the sensor device in consumer electronics.

[0083] The measurement process can be designed as a one-time measurement or as a periodic measurement cycle.

[0084] In particular, the sensor device can be designed to offer different operating modes in which different components are active to varying degrees. Examples of operating modes include standby mode, measurement mode, post-processing mode (measuring component deactivated, but signal processing active), forced mode (where the user intentionally performs a measurement), free-running mode (where measurements are taken at regular intervals, with this rate referred to as ODR (output data rate)), and / or non-stop mode (where measurements are taken continuously).

[0085] Furthermore, the sensor device can have a housing, wherein the optical source, the optical detector, the sensor element and the processing unit are arranged within the housing in such a way that a change in the physical quantity can cause at least partial deformation and / or at least partial deflection and / or at least partial change in the physical property of the sensor element.

[0086] This allows for the provision of a sensor device that is particularly easy to integrate into a higher-level system, for example, an R. 416383.

[0087] - 16 -

[0088] The sensor can be integrated into a mobile phone or smartwatch. This is partly because all necessary components of the sensor device are compactly arranged within the housing, eliminating the need for additional external components to capture the physical data. The housing protects the components from unwanted external influences such as moisture or mechanical stress, which could potentially damage them. Integration into a miniaturized housing, particularly based on established MEMS technology, makes the sensor device exceptionally compact and cost-effective to manufacture.

[0089] One embodiment of the invention provides that the sensor unit is designed in such a way that the influence of the movement of the sensor device on the detection of the physical quantity can be at least partially compensated by the design of the sensor unit.

[0090] The advantage here is that the sensor unit is designed to compensate for the influence of movement directly. This eliminates the need for downstream signal processing, allowing the sensor unit to capture a measurement signal without delay, exhibiting no or only minimal interference caused by movement. This type of compensation can be described as passive compensation. Passive compensation can therefore operate without delay and is also very energy-efficient, especially compared to active compensation.

[0091] A further embodiment of the invention provides that the optical path of the sensor unit and / or the light beam passing through the optical path is designed to be opposite in direction and / or mirror-symmetric.

[0092] The advantage here is that this represents a simple way to implement the self-compensation of the movement by the sensor unit itself.

[0093] One possible design for the sensor unit is to ensure that the light beam travels symmetrically within the sensor element, for example, by being reflected in a mirror. Thus, the R. 416383

[0094] - 17 -

[0095] The light beam traverses the optical path twice in opposite directions or with slight deviations. All motion effects thus essentially have a double impact on the light beam, but with opposite signs. This results in the interference signals caused by the movement canceling each other out or at least reducing their effect. This is particularly advantageous because the optical signal travels at the speed of light, meaning that even arbitrarily fast and erratic movements can be treated as static situations. This approach is especially suitable when a large portion of the sensor unit can be traversed in both directions, for example, when using a vertical cavity surface-emitting laser (VCSEL) with an integrated photodiode (ViP), where the source and detector are located together.

[0096] It is also possible for the light beam to travel along the optical path in only one direction, while the optical path itself is arranged in the opposite direction. For example, a certain number of turns of the optical path could run clockwise, followed by the same number of turns counterclockwise. It is important to note that the path segments should be as close to each other as possible, taking into account the slightly different radii. Alternatively, the opposing path segments can be superimposed to achieve identical radii.

[0097] Opposing here means that the light beam and / or the optical paths run in opposite directions.

[0098] According to a further embodiment of the invention, the sensor device has a further sensor unit, wherein the sensor device is configured to detect the movement of the sensor device, particularly during the detection of the physical quantity, by means of the further sensor unit and / or to at least partially compensate for the influence of the movement on the detection of the physical quantity, particularly by means of the further sensor unit.

[0099] An advantage here is that, depending on the design of the additional sensor unit, either passive or active compensation of the movement's influence can be achieved. Passive compensation can be achieved by R. 416383

[0100] - 18 - the sensor unit and the other sensor unit are designed and arranged in such a way that the movement has no influence on a final measurement result, as the interfering influences acting on the two sensor units cancel each other out. Such passive compensation can therefore function without delay and is also very energy-efficient, especially compared to active compensation.

[0101] In contrast, active compensation uses information about the sensor device's movement, acquired by an additional sensor unit, to compensate for errors in the sensor unit's output signal that were caused by the sensor device's movement. Such active compensation can be performed by the sensor device itself or by a higher-level system. Advantageously, the degree of compensation can be adjusted, or external factors can be taken into account, such as the sensor's movement within a reference system when compensation is required with respect to a different reference system.

[0102] According to a further embodiment of the invention, the additional sensor unit is designed at least as an accelerometer and / or as a gyroscope.

[0103] The advantage here is that by designing the additional sensor unit as an inertial sensor, precise motion detection is possible, the influence of which can then be actively compensated by the sensor device or a higher-level system. A further advantage is that such inertial sensors typically have a significantly higher measurement rate than environmental sensors, such as pressure sensors, and are therefore well-suited as a basis for the active compensation of motion influence due to their excellent resolution. This also results in a multi-sensor system that can detect several physical quantities and consequently offers a wide range of applications. Typical motion sensors consist of several individual detectors, for example, three structures for detecting accelerations and / or three further structures for detecting rotations.Typical measuring principles of such sensors are capacitive or piezoresistive. R. 416383.

[0104] - 19 -

[0105] According to a further embodiment of the invention, the additional sensor unit is provided to have an optical measuring principle.

[0106] The advantage here is that both sensor units of the sensor device have an identical measuring principle. Therefore, the movement of the sensor device affects both sensor units, although this may be desirable for the second sensor unit in order to determine or compensate for the influence on that unit.

[0107] According to a further embodiment of the invention, the sensor device is configured such that the additional sensor unit utilizes the optical source and / or the optical detector of the sensor unit. An advantage here is that optical sensor units typically require an optical source, an optical detector, and optical structures that interact with the quantity to be detected. Depending on the specific implementation, several sources and detectors, as well as a larger number of optical structures and other elements such as waveguides, optical paths, dividers, or combiners / collectors, may be required. Typically, not only are optical structures that interact with the quantity to be detected needed, but also optical reference structures that do not interact.In a sensor device with multiple sensor units, each employing a different optical measurement principle, it is advantageous to reuse some of these optical elements, particularly optical sources and / or detectors and / or parts of the waveguides or optical paths. Specifically, this could mean using one optical source for multiple sensor units and, for example, directing the light beam via an optical splitter into different optical structures that interact with different physical quantities. This could be, for instance, one sensor element used for pressure detection and another for rotation detection, based, for example, on the well-known concept of a laser gyroscope. In particular, the split light beams passing through the sensor elements can be guided to a common optical detector using a combiner, collector, or mirror.This synergy eliminates potentially redundant R. 416383.

[0108] - 20 -

[0109] This eliminates the need for multiple components, which can advantageously reduce the size, cost, susceptibility to errors, and / or energy consumption of the entire sensor device. Ideally, the different sensor subsystems should be controlled serially to ensure unambiguous signal differentiation. However, parallel control is also possible in principle, as long as the signals can be distinguished, for example, by using different frequencies or structured input signals.

[0110] According to a further embodiment of the invention, the sensor unit and the further sensor unit are designed and arranged in such a way that influences on the detection of the physical quantity generated by the movement of the sensor device at least partially compensate each other, in particular by the sensor unit and the further sensor unit having optical paths arranged in opposite directions and / or mirror symmetrically and / or light rays passing through the optical paths in opposite directions and / or mirror symmetrically.

[0111] The advantage here is that the influence of movement on the measurement of the physical quantity is passively compensated. In this case, the second sensor unit also measures the physical quantity. For example, the two optical structures are arranged as mirror images. In this scenario, movement effects have a positive impact on one sensor unit and a negative impact on the second sensor unit (positive and negative effects can, of course, also be inverted). This results in the effect caused by movement being mutually canceling each other out.

[0112] According to a further embodiment of the invention, it is provided that the sensor unit and the further sensor unit are each connected as part of a bridge circuit and, in particular, form different bridge elements of the bridge circuit.

[0113] The advantage here is that this provides a simple way to implement passive compensation for the influence of motion on the measurement of the physical quantity. In particular, this also allows for the compensation of other disturbances, such as those caused by temperature changes. R. 416383

[0114] - 21 -

[0115] Accordingly, it is advantageous to use the two sensor units as two measuring elements and to design them in such a way that motion effects (and other effects such as temperature influences) are compensated for. For example, the sensor units can be arranged in parallel but connected in a mirror image configuration. In this case, motion effects affect the optical structures equally, but their effect cancels out in the inverted connection.

[0116] One obvious implementation is derived from a Wheatstone bridge circuit, which, as a full bridge, consists of two reference elements and two measuring elements and can compensate for disturbances such as temperature influences. Besides a full bridge, other implementations suitable for compensating for motion effects can also be used, e.g., a cleverly chosen half-bridge.

[0117] Furthermore, the sensor element can include at least one additional optical path for an additional light beam, whereby the additional optical path is not influenced by the physical quantity. This additional optical path can be used as a reference path, which, together with the optical path serving as the measurement path, can be used to achieve a good output signal, good common-mode rejection, and compensation for temperature influences. In particular, the sensor device can form a corresponding half-bridge circuit consisting of the measurement path and the reference path. Specifically, by comparing the signals from the measurement path and the reference path, high measurement accuracy and compensation for disturbances, such as temperature drift, can be achieved.

[0118] Drawings

[0119] Fig. 1 shows a first embodiment of a sensor device according to the invention in a side sectional view.

[0120] Fig. 2 shows a second embodiment of a sensor device according to the invention in a side sectional view. R. 416383

[0121] - 22 -

[0122] Fig. 3 shows a third embodiment of a sensor device according to the invention in a side sectional view.

[0123] Fig. 4 shows a circuit diagram of a sensor device designed according to the invention.

[0124] Fig. 5 shows a section of a fourth embodiment of a sensor device according to the invention in a schematic top view.

[0125] Description of exemplary implementations

[0126] Fig. 1 shows a first embodiment of a sensor device according to the invention in a perspective view.

[0127] The figure shows a sensor device 10 for detecting a physical quantity 110 acting on the sensor device 10, wherein the sensor device 10 is particularly suitable for applications in consumer electronics such as in a mobile phone or a smartwatch. The physical quantity 110 is symbolized here by an arrow as the pressure of a medium, e.g., air, acting on the sensor device 10 in the vicinity of the sensor device 10.

[0128] The sensor device 10 comprises a sensor unit 11 with an optical measuring principle and a processing unit 15. The sensor unit 11 in turn comprises an optical source 20, an optical detector 30 and a sensor element 40.

[0129] The processing unit 15, implemented as an ASIC, is configured to emit a light beam 21 via the optical source 20 within an optical path 25 towards the optical detector 30. The light beam 21 travels through the optical path 25, which passes through the sensor element 40. The optical path 25 can, for example, be configured as a waveguide. R. 416383

[0130] - 23 -

[0131] The sensor element 40 encompasses the optical path 25 at least partially and is designed such that, in the event of at least partial deformation and / or at least partial deflection and / or at least partial change of a physical property of the sensor element 40, which occurs in particular due to a change in the physical quantity 110 to be measured by the sensor device 10, the optical path 25 changes at least in certain areas.

[0132] For this purpose, the sensor element 40 has a membrane 41 that is at least partially isolated, and the membrane 41 is deformable and / or deflectable by a change in pressure acting on it. The membrane 41 borders at least partially on the optical path 25. If the membrane 41 is deformed accordingly by a change in pressure, this directly affects the optical path 25 and the light beam 21.

[0133] Furthermore, the sensor element 40 has a hermetically sealed cavity 43, with the membrane 41 spanning the cavity 43. The membrane 41 causes a change in the optical path 25 when the pressure changes. The light beam 21 is guided in such a way that the influence of the movement of the sensor device 10 on the detection of the physical quantity 110 can be at least partially compensated by the design of the sensor unit 11. This is achieved by ensuring that the light beam 21 traveling through the optical path 25 is mirror-symmetrical and is reflected accordingly at the wall of the cavity 41 opposite the optical source 20 and the optical detector 30. Alternatively or additionally, the optical path 25 could also be designed to run in the opposite direction to guide the light beam 21 accordingly.

[0134] The processing unit 15 is also configured to detect changes in the light beam 21 traversing the optical path 25 using the optical detector 30 and to determine the physical quantity 110 as a function of this change. The change in the light beam 21 can, for example, include a phase shift and / or a change in the intensity distribution and / or a change in the amplitude. R. 416383

[0135] - 24 -

[0136] In particular, the processing unit 15 can be configured to control the optical source 20 and / or the optical detector 30 only during a measurement process.

[0137] Furthermore, the sensor device 10 has a housing 60. The housing 60 comprises a printed circuit board 62 and a laterally surrounding, in particular metallic, side wall 63 and defines a receiving space within which the sensor unit 11 with optical source 20, optical detector 30 and sensor element 40, as well as the processing unit 15, are arranged such that a change in the physical quantity 110 can cause at least partial deformation and / or at least partial deflection and / or at least partial alteration of the physical property of the sensor element 40. The processing unit 15 is mounted on the printed circuit board 62. The sensor element 40 is in turn arranged on the processing unit 15, with electrical connections between the printed circuit board 62, the processing unit 15 and the sensor element 40 being established by corresponding bond wires 65.The electrical components are covered by a protective layer 64, which is of a particularly gel-like nature and is designed in such a way that the physical quantity 110 is transmitted to the sensor element 40 via the protective layer 64.

[0138] In particular, the housing 60 has a through-opening 61 from the interior of the housing to the environment of the sensor device 10. The through-opening 61 allows the medium to be measured to enter the interior of the housing unimpeded from the environment of the sensor device 10, where it can interact with the membrane 41 of the sensor element 40 via the protective layer 64. Furthermore, a sealing element 66, designed as an O-ring, is arranged on the housing 60, which enables the integration of the sensor device 10 into a higher-level system (not shown), such as a mobile phone or a smartwatch.

[0139] The optical source 20 comprises, for example, a laser which emits the light beam 21. The optical source 20 is integrated into the sensor element 40, wherein the light beam 21 can be coupled into the optical path 25, in particular by means of a grating coupler and / or a taper. R. 416383

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[0141] The optical detector 30 can, for example, comprise a multimode interferometer and / or frequency comb and / or detector for resonance peak displacements and / or macroscopic resonator, wherein the optical detector 30 is also integrated into the sensor element 40.

[0142] In an alternative embodiment not shown in the illustration, the sensor device 10 can be designed such that a first pressure from a first area of ​​the environment of the sensor device 10 acts on the top of the membrane 41 and a second pressure from a second area of ​​the environment of the sensor device 10 acts on the underside of the membrane 41.

[0143] In another alternative embodiment, not shown in the illustration, the membrane 41 can also at least partially encompass the optical path 25 and accordingly the optical path 25 can be integrated into the membrane 41.

[0144] Fig. 2 shows a second embodiment of a sensor device according to the invention in a side sectional view.

[0145] A sensor device 10 similar to that shown in Fig. 1 is depicted. However, the sensor device 10 according to Fig. 2 has a further sensor unit 12, wherein the sensor device 10 is configured to detect the movement of the sensor device 10, in particular during the detection of the physical quantity 110, by means of the further sensor unit 12 and / or to at least partially compensate for the influence of the movement on the detection of the physical quantity 110, in particular by means of the further sensor unit 12.

[0146] Here, the additional sensor unit 12 is configured at least as an accelerometer and / or as a gyroscope and can, for example, have an optical, a capacitive, or a piezoresistive measuring principle. The processing unit 15 can be configured to detect the movement of the sensor device 10 by means of the additional sensor unit 12 and to determine the influence of the movement on the R. 416383 detected by means of the sensor unit 11.

[0147] - 26 - to actively compensate, at least partially, for the physical quantity after its detection.

[0148] The sensor unit in turn has a sensor element 40 with integrated optical source 20 and integrated optical detector 30.

[0149] The membrane 41 has a T-shaped element 42 that extends from the membrane 41 into the cavity 43. The optical path 25 borders the element 42 of the membrane 41 and can be influenced by a movement of the membrane 41, which in turn affects the light beam 21. The light beam 21 is guided in such a way that reflections at the walls of the cavity 43 of the sensing element 40 and the T-shaped element 42 of the membrane 41 are used, for example, to achieve a change in the light beam 21 caused by a change in path length.

[0150] Alternatively or additionally, an increase in ambient pressure can deform the membrane 41 in such a way that the T-shaped element 42 of the membrane 41 moves into the optical path 25 or squeezes the optical path 25 and thereby partially blocks the light beam 21, thus changing the intensity distribution of the light beam 21.

[0151] Fig. 3 shows a third embodiment of a sensor device according to the invention in a side sectional view.

[0152] In this variant, the sensor device 10, like the sensor device according to Fig. 2, has a sensor unit 11 and a further sensor unit 12. Both the sensor unit 11 and the further sensor unit 12 have an optical measuring principle and both serve to detect the physical quantity 110. The further sensor unit 12 has a further sensor element 45, which has a further membrane 46 over a further cavity 48. In addition, the further sensor unit 12 has a further optical source 22 and a further optical detector 32. Here, the sensor unit 11 and the further sensor unit 12 are designed and arranged in such a way that influences on the detection of the physical quantity 110 generated by the movement of the sensor device 10 at least partially compensate for each other, as the sensor unit 11 and the further sensor unit 12 R. 416383

[0153] - 27 - light rays 21, 23 passing through the optical paths 25, 26 in a mirror-symmetric manner. A possible connection of the two sensor units 11 and 12 is shown by way of example in Fig. 4. An alternative embodiment of the two optical paths 25 and 26 is shown by way of example in Fig. 5.

[0154] Fig. 4 shows a circuit diagram of a sensor device designed according to the invention.

[0155] The diagram shows a simplified circuit diagram of a Wheatstone bridge circuit configured as a full bridge, as exemplified by the sensor device 10. The optical source 20 emits light into the optical paths 25 and 26, which serve as measurement paths, and into the additional optical paths 27, which serve as reference paths but are not influenced by the physical quantity 110. Here, the optical path 25 of the sensor unit 11 and the additional optical path 26 of the additional sensor unit 12 are each connected as part of a bridge circuit and form different bridge elements of the bridge circuit.

[0156] The optical detector 30 uses at least one measuring element 31 to detect the change that the respective light beam undergoes in the respective path 25, 26. The processing unit 15 acquires the signals acquired by the optical detector 30, thereby compensating for temperature influences and other disturbances, which increases the measurement accuracy of the sensor device 10.

[0157] In an alternative embodiment, not shown in the illustration, the circuitry of the sensor device 10 can be designed as a half-bridge and have an optical source 20, an optical detector 30 and only two optical paths, which in particular form the reference path and the measurement path.

[0158] Fig. 5 shows a section of a fourth embodiment of a sensor device according to the invention in a schematic top view. R. 416383

[0159] - 28 -

[0160] The optical path 25 of sensor unit 11 and the further optical path 26 of the further sensor unit 12 are shown. The optical paths 25 and 26 are fed by a common optical source 20 and run in a mirror-symmetric arrangement up to a common optical detector 30. The sensor device 10 is therefore designed such that the further sensor unit 12 uses the optical source 20 and the optical detector 30 of sensor unit 11.

[0161] Optical paths 25 and 26 are of course fully defined, with the dashed lines serving only to avoid creating intersections in the visualization.

Claims

1. R. 416383 - 29 - Claims 1. Sensor device (10) for detecting a physical quantity (110) acting on the sensor device (10), in particular an ambient pressure of the sensor device (10), wherein the sensor device (10) has a sensor unit (11) with an optical measuring principle, and wherein the sensor device (10) is configured to detect the physical quantity (110) by means of the sensor unit (11) and to detect any movement of the sensor device (10) that occurs, in particular during the detection of the physical quantity (110), and / or to at least partially compensate for any influence of the movement on the detection of the physical quantity (110).

2. Sensor device (10) according to claim 1, characterized in that the sensor device (10) comprises a processing unit (15) and that the sensor unit (11) comprises an optical source (20), an optical detector (30) and a sensor element (40), wherein the processing unit (15) is configured to emit a light beam (21) by means of the optical source (20) within an optical path (25) towards the optical detector (30), wherein the sensor element (40) at least partially encompasses the optical path (25) and is configured such that, in the event of at least partial deformation and / or at least partial deflection and / or at least partial change of a physical property of the sensor element (40), which occurs in particular due to a change in the physical quantity (110) to be measured by the sensor device (10), the optical path (25) changes at least partially.and wherein the processing unit (15) is configured to detect a change in the light beam (21) passing through the optical path (25) by means of the optical detector (30) and to determine the physical quantity (110) as a function of this change.

3. Sensor device (10) according to one of the preceding claims, characterized in that the sensor unit (11) is designed such that the influence of the movement of the sensor device (10) on the detection of the R. 416383 - 30 - physical quantity (110) can be at least partially compensated for by the design of the sensor unit (11).

4. Sensor device (10) according to claim 3, characterized in that the optical path (25) of the sensor unit (10) and / or the light beam (21) passing through the optical path (25) is designed to be opposite in direction and / or mirror-symmetric.

5. Sensor device (10) according to one of the preceding claims, characterized in that the sensor device (10) has a further sensor unit (12), wherein the sensor device (10) is configured to detect the movement of the sensor device (10) which occurs in particular during the detection of the physical quantity (110) by means of the further sensor unit (12) and / or to at least partially compensate for the influence of the movement on the detection of the physical quantity (110) in particular by means of the further sensor unit (12).

6. Sensor device (10) according to claim 5, characterized in that the further sensor unit (12) is configured at least as an accelerometer and / or as a gyroscope.

7. Sensor device (10) according to claim 5 or 6, characterized in that the further sensor unit (12) has an optical measuring principle.

8. Sensor device (10) according to claim 7, characterized in that the sensor device (10) is designed such that the further sensor unit (12) uses the optical source (20) and / or the optical detector (30) of the sensor unit (11).

9. Sensor device (10) according to claim 7 or 8, characterized in that the sensor unit (11) and the further sensor unit (12) are designed and arranged such that influences on the detection of the physical quantity (110) generated by the movement of the sensor device (10) at least partially compensate each other, in particular by the sensor unit (11) and the further sensor unit (12) being arranged in opposite directions and / or in a mirror-symmetric manner. R. 416383 - 31 - arranged optical paths (25, 26) and / or oppositely directed and / or mirror-symmetrical light rays (21, 23) passing through the optical paths (25, 26).

10. Sensor device (10) according to claim 9, characterized in that the sensor unit (11) and the further sensor unit (12) are each connected as part of a bridge circuit and in particular form different bridge elements of the bridge circuit.

Images