Piezoelectric resonator, method of using such a piezoelectric resonator, and multivariable sensor with such a piezoelectric resonator

Abstract

The invention relates to a piezoelectric resonator (1000) with a piezoelectric substrate (1100) having a base section (1110) and an excitation section (1120) and an electrode structure (1200) which is arranged at least partially on or in the excitation section (1120). Furthermore, the electrode structure (1200) comprises a first multifunctional electrode (1210) having a first main contact (1211) and a first secondary contact (1212). Furthermore, the invention comprises a multivariable sensor (4000) with the piezoelectric resonator (1000) and a method for using the piezoelectric resonator (1000).

Description

Technical Field

[0001] Piezoelectric resonators are important components in a wide range of electronic devices, especially in oscillators and filters. These resonators utilize the piezoelectric properties of specific materials to convert mechanical vibrations into electrical signals and vice versa. Background Technology

[0002] In the past, piezoelectric resonators were mainly developed in the form of crystal resonators and ceramic resonators. These resonators are characterized by their high stability and accuracy, making them ideal for applications in communications, the automotive industry, medical technology, and measurement technology.

[0003] A key area of ​​development is the integration of piezoelectric resonators into microelectromechanical systems (MEMS). MEMS resonators offer the advantage of miniaturized structures and can be used in a wide range of applications, such as sensing technology. The fabrication and qualification of these resonators require advanced manufacturing techniques and testing methodologies to ensure their performance and reliability.

[0004] In sensing technology, piezoelectric resonators are widely used, particularly for density and viscosity measurements in liquid media. These sensors perform precise measurements by first exciting the resonator to mechanical vibration, followed by analysis of the vibration's behavior, especially its damping characteristics. This allows for the accurate detection of changes in the density and / or viscosity of the surrounding medium. Such sensors are frequently used in industrial applications, such as for monitoring oil quality in machines and mobile machinery. Continuous monitoring of oil density and viscosity optimizes maintenance intervals and reduces downtime.

[0005] Despite technological advancements, challenges remain in optimizing the functionality and versatility of piezoelectric resonators. Summary of the Invention

[0006] The first aspect of the invention aims to address these challenges by providing a piezoelectric resonator with an innovative electrode structure. The second aspect of the invention relates to a method for using a piezoelectric resonator. The third aspect of the invention relates to the use of a piezoelectric resonator in a multivariable sensor. Advantageous designs and modifications of the various aspects of the invention are accordingly the object of the dependent claims.

[0007] According to a first aspect of the invention, a piezoelectric resonator includes a piezoelectric substrate with a base section and an excitation section, and an electrode structure, the electrode structure being arranged at least partially on or in the excitation section.

[0008] Here, the body made of piezoelectric material is referred to as the substrate, whose extension in one spatial direction (hereinafter referred to as the height or thickness of the substrate) is less than its extension in two spatial directions perpendicular to that spatial direction (hereinafter referred to as the length and width of the substrate). When the length of the piezoelectric substrate is mentioned below, it refers to the spatial extension direction of the substrate approximately corresponding to the extension of the substrate from the base section towards the excitation section. In an exemplary design, the substrate thickness can be between 100 and 350 micrometers, the width between 300 and 750 micrometers, and the length between 2500 and 10000 micrometers. These appropriate dimensions combine high stability with good vibration characteristics.

[0009] In the context of this document, all conductor tracks, electrodes, contacts, and other electronic structures are referred to as electrode structures, which, under certain circumstances, are included in the corresponding design schemes of piezoelectric resonators.

[0010] The base section is configured for connection to other components, such as the carrier or housing of a higher-level unit, like a multivariable sensor, which will be described in detail later. Furthermore, the electrical contacts, particularly contact pads, of the electrode structure can be arranged on the edge of the base section away from the excitation section, thereby spatially concentrating these electrical contacts for easy and reliable contact.

[0011] In the context of the arrangement of the electrode structure relative to the excitation section, "at least partially" means that the extension of the electrode structure along the length of the piezoelectric substrate overlaps with the piezoelectric substrate such that there is a non-zero intersection surface between the electrode structure and the excitation section. This makes it possible for the excitation section of the piezoelectric substrate to be effectively excited to mechanical vibration by a portion of the electrode structure (especially the electrodes). Preferably, the electrode structure overlaps with 25 percent of the length of the excitation section, more preferably with at least 50 percent of the length of the excitation section, and particularly preferably with approximately the entire length of the excitation section.

[0012] The arrangement of electrode structures (at least partially) on or within an excitation section indicates that various techniques can be used to connect or integrate the electrode structures to or into the piezoelectric substrate. When the electrode structures are (at least partially) arranged "on" the excitation section, it means that they are coated onto the surface of the piezoelectric substrate. For such an arrangement, methods such as physical vapor deposition (PVD) from the thin film technology group are considered, for example. Conversely, an arrangement (at least partially) within the piezoelectric substrate can mean that the electrode structures are embedded in the substrate body, i.e., by embedding the electrode structures into the surface of the substrate body, for example. Doping methods are considered for this purpose, for example. Similarly, in the sense of the invention, the arrangement of electrode structures between two bonded sublayers of a substrate constructed of multiple layers is understood as an arrangement within the substrate.

[0013] According to the present invention, the electrode structure of the piezoelectric resonator includes a first multifunctional electrode.

[0014] Conventional electrodes, as they are used in the prior art for charge transfer between the excitation section and the control electronics, have only one unique contact (hereafter referred to as a "single contact"), while the first multifunctional electrode has a first main contact and a first auxiliary contact. The first main contact and the first auxiliary contact can be constructed substantially the same, but are not directly shorted to each other, but are electrically separated from each other by the multifunctional electrode or are resistively, inductively, or capacitively coupled to each other only by the multifunctional electrode.

[0015] In other words, it becomes possible, through the first main contact and the first auxiliary contact, to implement various electronic measurements and / or operational functions using a multifunctional electrode, far exceeding the simple application of a potential or excitation signal (as is done with conventional electrodes in the prior art). For example, it is thus possible to perform voltage and / or resistance and / or capacitance measurements on the first multifunctional electrode between the first main contact and the first auxiliary contact. Similarly, for example, a heating current or test current can be guided through the first multifunctional electrode between the first main contact and the first auxiliary contact. Depending on the specific design of the first multifunctional electrode, a large number of additional measurement tasks or operational functions can thus be realized, as will be detailed in the examples below, thereby enabling the piezoelectric resonator to be used in a diverse and multifunctional manner, while simultaneously achieving a high degree of integration and miniaturization.

[0016] When a specific element, component, or functional unit is referred to as "first" here and below, this is solely for the purpose of clear naming. That is to say, the name should not be interpreted in a restrictive manner. Similarly, the name does not imply the presence or absence of other elements, components, or functional units of the same form. Therefore, naming a "first functional electrode" does not imply, nor exclude, the existence of a "second functional electrode." Furthermore, the first multifunctional electrode comprising a "first main contact" and a "first auxiliary contact" does not imply, nor exclude, that it also has other contacts.

[0017] In an exemplary design of the first aspect of the present invention, the electrode structure includes a first single-function electrode with a first single contact and a second single-function electrode with a second single contact.

[0018] When referring to a "second" element, component, or functional unit below, these names are merely for the purpose of explicit naming. This means that these names should be interpreted in no way restricted. Similarly, these names do not imply the presence or absence of another element, component, or functional unit of the same form. Therefore, the subsequent designation "second single-function electrode" neither implies nor excludes the existence of another functional electrode.

[0019] The first and second single-function electrodes may, for example, conform to conventional electrodes, as conventional electrodes are used in the prior art to excite piezoelectric resonators. They have only one unique contact sufficient to apply a potential or excitation signal. To clearly indicate that they have only one unique contact, these contacts are referred to as “single contacts” respectively. In contrast to the first multi-function electrode, these conventional electrodes are further referred to as “single-function” so as to illustrate that they are not suitable or constructed for implementing specific electronic measurements and / or operational functions that go beyond the simple application of the potential or excitation signal mentioned above.

[0020] The first and second single-function electrodes are respectively arranged at least partially on or in the excitation section, while the first multi-function electrode in this design is arranged at any location on the piezoelectric substrate, i.e., it may be arranged entirely on or in the base section or similarly at least partially on or in the excitation section. The expressions "at least partially" and "on or in" here express similar meanings as they have been expressed in the previous context regarding the arrangement of the electrode structure relative to the excitation section.

[0021] By incorporating two single-function electrodes (i.e., a first single-function electrode and a second single-function electrode) in this design, and arranging them at least partially on or within the excitation section, the excitation section of the piezoelectric substrate can be excited to mechanical vibration by applying excitation signals to the first and second single contacts, respectively. However, this design does not exclude the possibility that, if required by the substrate geometry (and, if necessary, the material properties of the selected piezoelectric material) or the desired form or quality of vibration, the electrode structure may also include additional single-function electrodes that also participate in the vibration excitation.

[0022] However, in this design, the first multifunctional electrode does not participate in the excitation of vibrations in the excitation zone, and therefore can be switched on at any time via the first main contact and the first auxiliary contact for the implementation of different measurement or operational functions. Therefore, it is not important whether the first multifunctional electrode is at least partially arranged on or within the excitation zone.

[0023] The piezoelectric resonator according to this design combines reliable vibration excitation and analysis of the excitation section with a large number of additional measurement and operation functions, which can be implemented simultaneously with vibration excitation or analysis using the first multi-functional electrode.

[0024] In another exemplary design of the first aspect of the invention, the electrode structure includes, in addition to the first multifunctional electrode, a first single-function electrode with a first single contact. Here, both the first single-function electrode and the first multifunctional electrode are arranged at least partially on or in the excitation section. The expressions “at least partially” and “on or in” here similarly express the meanings that have been correspondingly expressed in the previous context regarding the arrangement of the electrode structure relative to the excitation section.

[0025] By having two electrodes (i.e., a first single-function electrode and a first multi-function electrode) present in the same design, and with them at least partially arranged on or in the excitation section, the excitation section of the piezoelectric substrate can be excited to mechanical vibration by applying excitation signals to the first single contact of the first single-function electrode and to the first main contact and / or the first auxiliary contact of the first multi-function electrode, respectively. However, this design does not exclude the possibility, if required by the substrate geometry (and, if necessary, the material properties of the selected piezoelectric material) or the requirements for the form or quality of vibration, that the electrode structure also includes additional single-function electrodes or additional multi-function electrodes, which can also participate in vibration excitation.

[0026] In this design, the first multifunctional electrode thus possesses two functions, which can be associated with different operating or usage modes of the piezoelectric resonator:

[0027] In the first mode of use (which may also be referred to below as dynamic use or dynamic operation), the first multifunctional electrode directly participates in the excitation of vibrations in the region of the excitation segment. For this purpose, an excitation signal can be applied to the first multifunctional electrode through the first main contact, wherein either the same excitation signal is simultaneously applied to the first auxiliary contact or the first auxiliary contact is simultaneously electrically insulated from the excitation signal.

[0028] In the second mode of use (which may also be referred to below as static use or static operation), a number of additional measurement tasks or operational functions can be implemented using the multifunction electrode. For this purpose, the electrode is connected via a first main contact and a first auxiliary contact, and voltage, resistance, and / or capacitance measurements are performed on the first multifunction electrode, for example, between the first main contact and the first auxiliary contact. Similarly, the multifunction electrode can be electrically controlled, for example, by guiding a heating current or test current through the first main contact and the first auxiliary contact.

[0029] The piezoelectric resonator according to this design combines reliable vibration excitation and analysis of the excitation section with a large number of additional measurement and operational functions, which can be implemented using a first multifunctional electrode. Unlike the previously mentioned exemplary designs, vibration excitation and analysis, although performed, can be implemented non-parallel, i.e., not simultaneously, with the additional measurement and / or operational functions. This reduces the total number of conventional or single-function electrodes that must be at least partially arranged on or within the excitation section. This allows for a greater degree of miniaturization and integration while maintaining nearly the same level of versatility.

[0030] In another exemplary design of the first aspect of the invention, the electrode structure, in addition to the first multifunctional electrode, also includes a second multifunctional electrode with a second main contact and a second auxiliary contact. Here, both the first and second multifunctional electrodes are at least partially arranged on or in the excitation section. The expressions “at least partially” and “on or in” here similarly express the meanings that have been correspondingly expressed in the previous context regarding the arrangement of the electrode structure relative to the excitation section. The functions, designs, connections, possible advantages, usability, and differences from conventional (single-function) electrodes described above in the context of the first multifunctional electrode, the first main contact, and / or the first auxiliary contact are similarly applicable to the second multifunctional electrode, the second main contact, and the second auxiliary contact.

[0031] By incorporating two multifunctional electrodes (i.e., a first multifunctional electrode and a second multifunctional electrode) in this design, and having them at least partially arranged on or within the excitation section, the excitation section of the piezoelectric substrate can be excited to mechanical vibration by applying excitation signals to the first main contact and / or the first auxiliary contact of the first multifunctional electrode and to the second main contact and / or the second auxiliary contact of the second multifunctional electrode, respectively. However, this design may, if required by the substrate geometry (and, if necessary, the material properties of the selected piezoelectric material) or the requirements for the type or quality of vibration, also include additional single-function electrodes or additional multifunctional electrodes, which can also participate in vibration excitation.

[0032] Therefore, not only the first multifunctional electrode but also the second multifunctional electrode in this design have two functions, which are related to the two different operating or usage modes of the piezoelectric resonator, namely dynamic use and static use.

[0033] Here, the descriptions of dynamic or static use in the context of the previously exemplary design schemes are equally applicable to the first and second multifunctional electrodes.

[0034] As with the previously mentioned exemplary design, the piezoelectric resonator of this design also combines reliable vibration excitation and analysis of the excitation section with a large number of additional measurement and operation functions, which can be implemented using a first multifunctional electrode and a second multifunctional electrode. In particular, in this design, different measurement and operation functions can be implemented simultaneously using the first and second multifunctional electrodes, thereby allowing for more diverse uses of the piezoelectric resonator. Similarly, the total number of conventional or single-function electrodes that must be at least partially arranged on or within the excitation section can be further reduced. This allows for a higher degree of miniaturization and integration while maintaining high versatility.

[0035] In another exemplary design of the first aspect of the invention, the electrode structure, in addition to the first and second multifunctional electrodes from the previous examples, also includes a third multifunctional electrode with a third main contact and a third auxiliary contact, and a fourth multifunctional electrode with a fourth main contact and a fourth auxiliary contact. Here, the first, second, third, and fourth multifunctional electrodes are each at least partially arranged on or in the excitation section. The expressions “at least partially” and “on or in” here similarly express the meanings that have been correspondingly expressed in the previous context regarding the arrangement of the electrode structure relative to the excitation section. The functions, designs, connections, possible advantages, possibilities of use, and differences from conventional (single-function) electrodes described above in the context of the first multifunctional electrode, the first main contact, and / or the first auxiliary contact are similarly applicable to the second, third, and fourth multifunctional electrodes, the second, third, and fourth main contacts, and the second, third, and fourth auxiliary contacts.

[0036] When specific elements, components, or functional units are referred to as "third" and / or "fourth" here and below, this is solely for the purpose of explicit naming. That is to say, these names are not to be interpreted in a restrictive manner. Similarly, these names do not imply the presence or absence of other elements, components, or functional units of the same form. Therefore, naming a "third functional electrode" neither implies nor excludes the existence of other multifunctional electrodes. Furthermore, the inclusion of "third main contact" and "third auxiliary contact" in the terminology does not imply or exclude the presence of other contacts. The term "third main / auxiliary contact" is used more precisely here for the explicit association of these contacts with respect to the "third" multifunctional electrode.

[0037] Here, the piezoelectric substrate may, for example, have a tuning fork shape, and the excitation section may include a first zinken and a second zinken. Here, a first multifunctional electrode and a second multifunctional electrode may be at least partially disposed in or on the first zinken, while a third and fourth multifunctional electrode may be at least partially disposed in or on the second zinken. Through this appropriate design, the piezoelectric resonator can be precisely excited to vibrate, achieving a high degree of miniaturization, integration, and multifunctionality. Furthermore, the number of conventional or single-function electrodes that must be at least partially disposed on or in the excitation section is significantly reduced.

[0038] Similarly, at least the first and second multifunctional electrodes, but also, for example, the third and fourth multifunctional electrodes, may be arranged on different surfaces of the piezoelectric substrate or in different surfaces. For example, the first and / or third multifunctional electrodes may be arranged on or in the first surface of the substrate, while the second and / or fourth multifunctional electrodes may be arranged on or in the second surface of the substrate. Here, the first and second surfaces are opposite to each other. For example, the front side of the piezoelectric resonator is constructed from the first surface, and the back side is constructed from the second surface.

[0039] The expressions "at least partially" and "on or in" here express, respectively, the meanings of "at least partially" or "on or in" that have been expressed in the previous context regarding the arrangement of the electrode structure relative to the excitation section. With this design, the corresponding multifunctional electrodes can be constructed over a particularly large area, making them effective for the excitation and / or analysis of vibrations in the excitation section. Furthermore, the large-area design of the electrodes allows for improved sensitivity and measurement accuracy in implementing additional measurement or operational functions (e.g., in the previously mentioned static operation). It also facilitates the fabrication of the piezoelectric resonator.

[0040] The multifunctional electrodes present in the previously exemplary design schemes, namely the first multifunctional electrode, the second multifunctional electrode, the third multifunctional electrode and / or the fourth multifunctional electrode (hereinafter collectively referred to as "multifunctional electrodes"), may each have at least one of the following design schemes.

[0041] Regardless of the number of multifunctional electrodes on the piezoelectric resonator, each multifunctional electrode may include a resistance rail or a capacitor. Therefore, the most diverse combinations of resistance rails and capacitors can be conceived on or at the piezoelectric resonator, such as two or more capacitors, two or more resistance rails, or at least one resistance rail and at least one capacitor. Further embodiments and examples of this can be found in the description below.

[0042] For example, at least one of the multifunctional electrodes may have a resistance rail extending from a first end to a second end. Here, the first end is electrically connected to a corresponding main contact of the corresponding multifunctional electrode, and the second end is electrically connected to a corresponding secondary contact of the corresponding multifunctional electrode, so that resistance measurement of the resistance rail can be performed between the corresponding main contact and the secondary contact, or current can be guided through the resistance rail.

[0043] The material used to manufacture the resistance rail can have a temperature-dependent resistance, thus enabling temperature measurement by measuring the resistance between the corresponding main contact and the corresponding secondary contact of the respective multifunctional electrode.

[0044] Similarly, the material used to manufacture the resistance rail can also have a resistance that depends on the concentration of the target medium in the surrounding environment of the resistance rail. "Surrounding environment" here means that the target medium, especially when dissolved in the main medium, at least surrounds the excitation section of the piezoelectric resonator, and is in direct contact with the excitation section. The target medium can be, for example, water, and the main medium can be oil. With such a design, concentration measurement, such as humidity measurement, can be performed by means of resistance measurement between the corresponding main contacts and corresponding secondary contacts of the corresponding multifunctional electrodes. For example, excessively high water content in engine oil or hydraulic oil can lead to increased wear. By periodically measuring humidity, critical ranges can be determined in a timely manner, and appropriate measures can be taken.

[0045] Alternatively or additionally, the resistance rail can be configured as a heating resistor. This means that it is designed to be heated to a defined heating temperature when a heating current is guided through the corresponding main contacts and corresponding secondary contacts of the heating resistor. Here, the heating temperature can be determined, in particular, by the ambient or medium temperature (approximately 10 Kelvin above the medium temperature) or determined to an absolute value (e.g., slightly below 100°C). This enables a variety of measurement and operational functions, which are further illustrated below with examples.

[0046] Regardless of the material the resistance rail is made of or whether it is constructed as a heating resistor, the resistance rail can be zigzag-shaped. This allows for a significant increase in the length of the resistance rail between its first and second ends, while maintaining the same area requirement.

[0047] Furthermore, it can be specified that the resistive rail covers at least 50 percent, preferably even at least 75 percent, of the surface of the excitation region of the substrate or (if the piezoelectric substrate has a tuning fork shape) the surface of the interdigitated fingers, thereby enabling the corresponding multifunctional electrode to be used particularly efficiently for exciting and / or analyzing the vibration of the excitation segment and to achieve improved sensitivity and measurement accuracy in cases where additional measurement or operational functions are implemented.

[0048] Furthermore, at least one of the multifunctional electrodes may include, for example, a capacitor.

[0049] Here, the capacitor has a first capacitor electrode that is electrically connected to a corresponding main contact, and a second capacitor electrode that is electrically connected to a corresponding secondary contact.

[0050] Here, the capacitor can be configured, for example, as an interdigitated capacitor and constructed on or within the surface of the excitation section, covered with an insulating layer or passivation layer. Alternatively, the capacitor can also be configured as a parallel-plate capacitor, wherein the first capacitor electrode is insulated from the second capacitor electrode through a piezoelectric substrate or a sublayer of the piezoelectric substrate, and wherein the two capacitor electrodes are electrically insulated from the surrounding environment of the piezoelectric resonator through a sublayer of the substrate or through an insulating layer. Therefore, the dielectric constant of the medium surrounding the piezoelectric resonator can be measured by capacitance measurement between the respective main contacts and the respective secondary contacts of the respective multifunctional electrodes.

[0051] Similarly, the capacitor can be constructed in the form of a parallel-plate capacitor, wherein the first capacitor electrode is insulated from the second capacitor electrode by a dielectric interlayer. Here, the material forming the dielectric interlayer can be chosen such that its dielectric constant depends on the concentration of the target medium in the capacitor's surrounding environment. "Surrounding environment" here means that the target medium, particularly dissolved in the main medium, at least surrounds the excitation section of the piezoelectric resonator, and is in direct contact with the excitation section. The target medium can be, for example, water, while the main medium is oil.

[0052] This design allows for concentration measurements, such as humidity measurements, to be performed by capacitance measurement between the corresponding main contacts and corresponding secondary contacts of the respective multifunctional electrodes. Specifically, a first capacitor electrode is disposed as a planar electrode on or within the surface of the excitation section, at least partially covered by an intermediate layer, while a second capacitor electrode is disposed above the intermediate layer, facing the surrounding environment of the piezoelectric resonator. The second capacitor electrode may, in particular, have a comb-like structure, especially a comb-like structure with lateral teeth between the comb's interdigitates, or a grid structure or perforations, so that the intermediate layer is not completely obscured by the second capacitor electrode, and the target medium can effectively interact with the intermediate section.

[0053] Due to the planar design of the first capacitor electrode (i.e., a closed surface), which is arranged as the bottom layer of the capacitor on or within the surface of the substrate, the corresponding multifunctional electrode can be used particularly effectively to excite and / or analyze the vibration of the excitation segment, and it can achieve improved sensitivity and measurement accuracy when implementing additional measurement or operational functions. It may be specifically specified here that the planar first capacitor electrode covers at least 50%, preferably even at least 75%, of the surface of the excitation region of the substrate or (if the piezoelectric substrate has a tuning fork shape) the surface of the interdigitated fingers.

[0054] In another exemplary design of the first aspect of the invention, the piezoelectric substrate is made of quartz, particularly alpha quartz. Alpha quartz, as the material used for the piezoelectric substrate, has very high frequency stability, thereby enabling the piezoelectric resonator made therefrom to have a very high quality factor. This makes it possible to determine the resonant frequency very precisely. Furthermore, when quartz is formed by anisotropic etching along a specific crystal direction or at a specific cutting angle, the substrate made of alpha quartz has low thermal cross-sensitivity. Moreover, the anisotropic quartz etching process can be very well controlled technically, thereby producing the desired target shape with high precision and reliability.

[0055] In another exemplary design of the first aspect of the invention, the piezoelectric substrate is made of a piezoelectric single crystal, or includes at least one such piezoelectric single crystal, wherein, in particular, lithium niobate (LiNbO3) is mentioned. LiNbO3 has a higher piezoelectric coupling coefficient than the previously mentioned quartz.

[0056] In another exemplary design of the first aspect of the invention, the piezoelectric substrate is manufactured as a single piece. This reduces the number of components and connectors, thereby lowering manufacturing costs and, compared to designs where the substrate is formed from multiple interconnected layers or sheets, improving the vibration and measurement characteristics of the piezoelectric resonator, as well as its stability and tolerance to mechanical, chemical, or other environmental loads.

[0057] According to a second aspect of the invention, a method for using a piezoelectric resonator according to a first aspect of the invention or according to one of the exemplary design schemes mentioned therein comprises the following steps, which are performed indirectly or directly in any order:

[0058] - Step A: Perform electrical measurement of the first multifunctional electrode between the first main contact and the first auxiliary contact, or electrically manipulate the first multifunctional electrode through the first main contact and the first auxiliary contact, and - Step B: Apply an excitation signal to the first multifunctional electrode through the first main contact, wherein either the same excitation signal is applied to the first auxiliary contact simultaneously or the first auxiliary contact is electrically isolated from the excitation signal simultaneously.

[0059] Step A corresponds to the previously described "static usage" of the piezoelectric resonator, while step B corresponds to the "dynamic usage." Regardless of which step is performed first, the piezoelectric resonator can be used automatically, multifunctionally, and therefore in many ways by the indirect or direct sequence of these steps. The sequence of these steps can be performed consecutively, for example, in a periodic variation, thereby allowing for the continuous execution of multiple measurement or operational tasks, for example. Here, "indirect" sequence or "indirectly" sequential execution means that at least one other additional step is performed between these steps (regardless of which is performed first). Conversely, if the steps are performed directly in sequence, this corresponds to "direct" sequence or "directly" sequential execution.

[0060] In an exemplary design of the second aspect of the invention, the first multifunctional electrode has a capacitor and the electrical measurements in step A include capacitance measurement and / or voltage measurement.

[0061] When the capacitor is configured as an interdigitated capacitor or when the capacitor has a first capacitor electrode and a second capacitor electrode (the second capacitor electrode is insulated from the first capacitor electrode through a piezoelectric substrate or a sublayer of the piezoelectric substrate), the dielectric constant of the medium surrounding the piezoelectric resonator can be effectively measured, as previously described with respect to the first aspect of the invention.

[0062] When the capacitor is constructed in the form of a parallel-plate capacitor, wherein the first capacitor electrode is insulated from the second capacitor electrode by a dielectric interlayer and the material constituting the dielectric interlayer is selected such that the dielectric constant of the dielectric interlayer depends on the concentration of the target medium in the environment surrounding the capacitor, so that the concentration measurement of the target medium can be effectively implemented as previously described with respect to the first aspect of the invention.

[0063] In another exemplary design of the second aspect of the invention, the first multifunctional electrode has a resistance rail and the electrical measurement in step A includes a resistance measurement.

[0064] Temperature measurement can be effectively implemented when the resistance rail is made of a material with resistance that depends on temperature.

[0065] When the resistance rail is made of a material having a resistance that depends on the concentration of the target medium in the surrounding environment of the resistance rail, the concentration measurement of the target medium can be effectively implemented, as previously explained with respect to the first aspect of the invention.

[0066] In another exemplary design of the second aspect of the invention, the first multifunctional electrode has a heating resistor, and the electrical operation in step A includes guiding heating current through the heating resistor via a first main contact and a first auxiliary contact.

[0067] In this design (where the first multifunctional electrode has a heating resistor), the piezoelectric resonator can be selectively and briefly heated via the heating resistor. This allows for thermal desorption and cleaning of the piezoelectric resonator, where contaminants, (especially organic) deposits, and the like are effectively removed from its surface when heated. Simultaneously, heating reduces the viscosity of many media. Particularly when the excitation section of the piezoelectric resonator is excited to vibrate immediately following step A and then in step B, the removal of contaminants and deposits from its surface is achieved more effectively.

[0068] Here, the electrode structure may, for example, simultaneously have a second multifunctional electrode, which is also at least partially arranged on or in the excitation section, and the second multifunctional electrode has a second main contact and a second auxiliary contact, and the second multifunctional electrode is constructed in the form of a parallel plate capacitor, wherein the first capacitor electrode is insulated from the second capacitor electrode by a dielectric interlayer, and the material constituting the dielectric interlayer is selected such that the dielectric constant of the dielectric interlayer depends on the concentration of the target medium in the environment surrounding the capacitor.

[0069] Here, the first multifunctional electrode is at least partially disposed on or therein on the first surface of the piezoelectric substrate, while the second multifunctional electrode is at least partially disposed on or therein on the second surface of the piezoelectric substrate, the second surface being opposite to the first surface. This arrangement effectively achieves the following: when the heating resistor is electrically operated in step A, the second multifunctional electrode and, consequently, the dielectric interlayer surrounded by the second multifunctional electrode, can be targeted for heating.

[0070] The heating effect can be achieved particularly efficiently when the first multifunctional electrode and the second multifunctional electrode are arranged to at least partially overlap in a top view of one of the surfaces.

[0071] By targeting the medium with heat, residues of the target medium that may accumulate in the dielectric interlayer can be effectively thermally desorbed, allowing for accurate measurement of the target medium's concentration. This method proves particularly useful when the target medium is water, i.e., when the second multifunctional electrode is configured as a humidity sensor. Effective thermal desorption of the dielectric interlayer is achieved by heating to a temperature slightly below 100°C. Thermal desorption of water minimizes potential interference with humidity measurement, allowing the humidity sensor to once again provide accurate and less erroneous humidity readings.

[0072] In another exemplary design of the second aspect of the invention, the first multifunctional electrode again has a heating resistor, and the electrode structure additionally has a second multifunctional electrode, which is also at least partially disposed on or therein the excitation section, and has a second main contact and a second auxiliary contact. Here, the second multifunctional electrode has a resistance rail with a temperature-dependent resistance, and the first and second multifunctional electrodes are disposed together, however, laterally offset, on or therein on a surface of the piezoelectric substrate. The aforementioned lateral offset can be understood in particular as the spacing between the first and second multifunctional electrodes.

[0073] In this design, the electrical manipulation in step A during the first duration T1 includes guiding heating current through the heating resistor via the first main contact and the first auxiliary contact, wherein, immediately or at least partially simultaneously during the second duration T2, a resistance measurement between the second main contact and the second auxiliary contact is performed on the resistance rail of the second multifunctional electrode. The flow velocity of the medium surrounding the piezoelectric resonator in the lateral offset direction between the first and second multifunctional electrodes can be inferred from the magnitude and / or time shift of the measurable temperature increase on the second multifunctional electrode relative to the start and / or end of duration T1.

[0074] Specifically, it can be specified here that a first multifunctional electrode with a heating resistor is positioned before a second multifunctional electrode with a resistance rail in the flow direction of the flowing medium. That is, the medium is first heated on the heating resistor of the first multifunctional electrode and then moves further along the flow direction toward the second multifunctional electrode. The temperature of the medium is measured on the second multifunctional electrode, from which the flow velocity of the medium can be derived.

[0075] Here, "at least partially simultaneous" can in particular mean that the second duration T2 begins simultaneously with the first duration T1, but continues after the first duration ends, or begins with a fixed time offset relative to the first duration T1.

[0076] In an exemplary design in which the piezoelectric substrate has a tuning fork shape with a first interdigitate and a second interdigitate, the method can be applied particularly effectively when both, i.e., the first and second multifunctional electrodes, are arranged on the same side of the substrate or in the same side, but on different interdigitates. The previously described offset, i.e., the spacing between the first and second multifunctional electrodes, can be achieved by arranging them on different interdigitates.

[0077] Regarding lateral offset, i.e., spacing, it is also possible that this lateral offset can be set by the thickness of the piezoelectric substrate. The previously described measurement of the medium flow rate can be performed by arranging two multifunctional electrodes on two different, particularly opposing, surfaces of the piezoelectric substrate. The two opposing surfaces can be, for example, the front and back sides of the piezoelectric substrate.

[0078] According to a third aspect of the invention, the multivariable sensor includes a piezoelectric resonator according to the first aspect of the invention or one of the exemplary designs described above, as well as control electronics and a first switch.

[0079] Control electronics can be configured, for example, in the form of integrated circuits, particularly as microcontrollers. This allows for high functionality in a small form factor, robust construction, and low current consumption.

[0080] The first switch is configured to electrically connect or provide the first main contact and the first auxiliary contact of the first multifunctional electrode separately to the control electronics in the first switch position, and to insulate the first auxiliary contact from the control electronics and / or short-circuit the first auxiliary contact from the first main contact in the second switch position, while the first main contact remains electrically connected or provided to the control electronics.

[0081] In this context, “electrical connection or provision” specifically means establishing electrical contact between the electronic interface of the control electronics and the first primary contact or the first secondary contact.

[0082] The first switch can be configured as a separate element or component, serving as an electronic connection between the control electronics and the first multi-function electrode. Alternatively, the control electronics and the first switch can also be combined in a single unit, such as in a microcontroller. In such a design, the first primary contact and the first secondary contact can be permanently connected to different electronic interfaces of the microcontroller (e.g., to different contact pins or inputs). The function of the switch, i.e., the implementation of the first or second switch position, is then purely logically mapped in the firmware stored in the microcontroller, which is also referred to below as wiring logic.

[0083] Regardless of how the first switch is designed (e.g., physically as a separate component or integrated into the microcontroller as wiring logic in data technology), the first switch in the first switch position enables the control electronics to perform a wide range of different measurement tasks or operational functions between the first main contact and the first auxiliary contact.

[0084] For example, the control electronics may be configured to perform voltage and / or resistance and / or capacitance measurements on a first multifunctional electrode between a first primary contact and a first secondary contact. The measurement results may be provided directly as a first measurement signal for further processing in an external unit, or they may be processed by the control electronics itself and provided as a first processed measurement value signal. In this context, "measurement signal" means a primary measurement result, such as resistance measured on a resistance rail, while the "processed measurement value signal" corresponds to a target quantity (e.g., ambient temperature) calculated based on the primary measurement result.

[0085] Alternatively or additionally, if the electrode includes a heating resistor, control electronics may be configured to guide a heating current or test current through the first multifunctional electrode between the first main contact and the first auxiliary contact.

[0086] In the second switch position, the control electronics, conversely, are positioned such that an excitation signal can be applied to the first multi-functional electrode via the first main contact, causing the first multi-functional electrode to participate in the vibration excitation of the excitation section and immediately afterward, the excitation signal is turned off, and an attenuation signal is received via the first main contact, which is then provided as a second measurement signal or as a second processed measurement value signal. During this period, the first auxiliary contact is either insulated from the control electronics (which, in the case where the first switch is implemented as part of an integrated control electronics device in the form of wiring logic in a microcontroller, could mean that no excitation signal, and in particular no potential, is applied to the first auxiliary contact), or the first auxiliary contact is short-circuited to the first main contact (which, in the case where the first switch is implemented as part of an integrated control electronics device in the form of wiring logic in a microcontroller, could mean that the same excitation signal is simultaneously and simply applied to the first auxiliary contact). In this context, "measurement signal" means a primary measurement result, such as the vibration frequency, vibration amplitude, or vibration damping derived from the attenuation signal, while the "processed measurement value signal" corresponds to a target quantity (e.g., viscosity or density) calculated based on the primary measurement result.

[0087] In an example design of the third aspect of the invention, a multivariable sensor is configured to implement one or more of the previously mentioned methods according to the second aspect of the invention using control electronics and piezoelectric resonators of respective configurations.

[0088] As can be seen from the foregoing, the multivariable sensor can automatically implement the switching between steps A and B mentioned herein in the method according to the second aspect of the invention via a first switch. The position of the first switch then corresponds precisely to the wiring configuration of the first multifunctional electrode, as required in the corresponding step A of the method (“static operation” or “static use”), while the position of the second switch corresponds to the wiring configuration, as required in the corresponding step B of the method (“dynamic operation” or “dynamic use”). Accordingly, these usage methods can be readily implemented by control electronics, for example, by storing corresponding instructions in the firmware of the control electronics configured as a microcontroller.

[0089] When the piezoelectric resonator according to one of the methods has additional multifunctional electrodes besides the first multifunctional electrode, such as a second multifunctional electrode with a second main contact and a second auxiliary contact, the first switch can be configured to simultaneously wire the contacts of all existing multifunctional electrodes, as previously described regarding the wiring of the first main contact and the first auxiliary contact of the first multifunctional electrode. Alternatively, the multivariable sensor can also have its own switch for each existing multifunctional electrode, i.e., a second switch for the second multifunctional electrode, a third switch for the third multifunctional electrode, and / or a fourth switch for the fourth multifunctional electrode. For any other switch, the same similarities described previously regarding the design and function of the first switch for the first multifunctional electrode apply to the design and function of any other switch for the respective associated multifunctional electrode.

[0090] This design of the multivariable sensor enables a large number of additional measurement and operational functions, making it extremely versatile and multifunctional.

[0091] In another exemplary design of the third aspect of the invention, the multivariable sensor includes a housing with a process interface and a signal interface.

[0092] The process interface is configured to be connected to a measurement point on a container or fluid pipeline, such as the oil tank of a mobile work machine. Furthermore, the process interface is sealed by a seal that prevents the medium from entering the housing of the multivariable sensor from the container or fluid pipeline. The excitation section extends beyond the seal, while the base section extends at least partially into the housing cavity. Thus, the excitation section can effectively interact with the medium within the container or fluid pipeline, while the base section is effectively protected from contact with the medium.

[0093] The seal can be configured, for example, as a glass through-hole, in which the piezoelectric substrate is embedded. This design achieves a particularly reliable and durable seal at the process interface, and also exhibits high resistance to chemical damage. Simultaneously, the glass connection used for sealing reinforces the piezoelectric substrate in the transition region between the excitation and base sections, effectively shielding the base section from oscillations and vibrations of the excitation section. When "glass" is used in this context, it can be understood specifically as inorganic glassy materials, such as oxide glasses (e.g., silicate glass, borosilicate glass, aluminosilicate glass, or other technical glasses) and / or glassy brazing materials, especially glass solder or glass powder, which may also be a (partially) crystalline or devitrified glass solder.

[0094] The disclosure of this document is not limited to the features of the exemplary embodiments and / or improvements mentioned above, but also includes any combination of these features, provided that they are not logically mutually exclusive. Attached Figure Description

[0095] Another exemplary design of the present invention is illustrated below with reference to the accompanying drawings. Wherein:

[0096] Figure 1A and 1B An exemplary design of a piezoelectric resonator is schematically shown in perspective views (front and back views, respectively).

[0097] Figure 2A and 2B The cross-sectional diagrams schematically illustrate the following: Figure 1A Different design schemes for piezoelectric resonators

[0098] Figure 3 A partial schematic view showing the proportions of the data. Figure 1A piezoelectric resonator,

[0099] Figure 4A The design of a first example of a multivariable sensor is schematically shown in a cross-sectional view.

[0100] Figure 4B The design of a second example of a multivariable sensor is schematically shown in a cross-sectional view.

[0101] Figure 5 Another implementation of a piezoelectric resonator is illustrated schematically.

[0102] Corresponding components are labeled with the same reference numerals in all drawings. Detailed Implementation

[0103] Figure 1A and 1B An exemplary design of a piezoelectric resonator 1000 according to a first aspect of the present invention is shown.

[0104] The piezoelectric resonator includes a piezoelectric substrate 1100 and an electrode structure 1200. The piezoelectric substrate has a tuning fork shape with an upper base section 1110 and a lower excitation section 1120. The lower excitation section has a first interdigital finger 1121 and a second interdigital finger 1122.

[0105] exist Figure 1A The piezoelectric resonator 1000 is shown in a front view or front view, making the first surface 1101 of the substrate 1100 visible. The electrode structure 1200 includes a first multifunctional electrode 1210, which is constructed on or in the first surface 1101 on the first interdigitator 1121.

[0106] exist Figure 2A (It is shown in enlarged form in) Figure 1A As indicated by the cross-section AA passing through the first interdigitated finger 1121, the first multifunctional electrode 1210 here includes a capacitor 3000 or a capacitor 3000 configured as such. The capacitor 3000 includes a first capacitor electrode 3001, which forms the closed bottom surface of the capacitor 3000. A dielectric interlayer 3003 is disposed above the first capacitor electrode, and a second capacitor electrode 3002 is disposed above the dielectric interlayer. The first capacitor electrode 3001 is electrically connected to a first main contact 1211, and the second capacitor electrode 3002 is electrically connected to a first secondary contact 1212 of the first multifunctional electrode. The dielectric interlayer 3003 has a dielectric constant that depends on the concentration of the target medium in the environment surrounding the capacitor, such as the concentration of water, thereby allowing the capacitor 3000 to be used as a humidity sensor. Because the second capacitor electrode 3002 has a comb-like structure with lateral interdigitated fingers, the dielectric surrounding the piezoelectric resonator 1000 can directly contact the dielectric intermediate layer 3003, thereby enabling the dielectric intermediate layer to effectively interact with the dielectric.

[0107] Figure 2B The above description was displayed. Figure 2A An alternative implementation scheme. The figure also shows a magnified portion of the first forked finger 1121. Unlike in... Figure 2A The implementation scheme shown herein includes capacitor 3000 in... Figure 2B The alternative embodiment shown is mounted on a largely flat substrate. The second capacitor electrode 3002 is partially covered by a dielectric interlayer 3003. Further reference can be made to the above-described alternative embodiment. Figure 2A Explanation of the procedure.

[0108] Furthermore, electrode structure 1200 includes a third multifunctional electrode 1230, which is constructed on or within the first surface 1101 on the second interdigital finger 1122 (see [link to documentation]). Figure 1A ).

[0109] As in Figure 3 (It is shown in a magnified detail view in) Figure 1A As can be seen in area B marked with a circle, the third multi-functional electrode 1230 also includes a capacitor 3000' or a capacitor configured as such. The capacitor 3000' is configured as an interdigitated capacitor, meaning that the first capacitor electrode 3001' and the second capacitor electrode 3002' of the capacitor 3000' each have a comb-like structure and are arranged alternately but electrically insulated from each other. The first capacitor electrode 3001' is electrically connected to the third main contact 1231, and the second capacitor electrode 3002' is electrically connected to the third auxiliary contact 1232 of the third multi-functional electrode 1230.

[0110] exist Figure 1B The piezoelectric resonator 1000 is shown in a rear view or from the back side, making the second surface 1102 of the substrate 1100 visible, which is opposite to the first surface 1101. The electrode structure 1200 includes a second multifunctional electrode 1220 formed on or in the second surface 1102 on the first interdigitator 1121, and the electrode structure 1200 includes a fourth multifunctional electrode 1240 formed on or in the second surface 1102 on the second interdigitator 1122.

[0111] The second multi-functional electrode 1220 includes a resistance rail 2000 extending from a first end 2001 to a second end 2002. The first end 2001 is electrically connected to a second main contact 1221, and the second end 2002 is electrically connected to a second auxiliary contact 1222 of the second multi-functional electrode 1220. Similarly, the fourth multi-functional electrode 1240 also includes a resistance rail 2000' extending from a first end 2001' to a second end 2002'. The first end 2001' is electrically connected to a fourth main contact 1241, and the second end 2002' is electrically connected to a fourth auxiliary contact 1242 of the fourth multi-functional electrode 1240. The resistance rails (2000, 2000') may, for example, have a spiral or zigzag orientation in the region between the first ends (2001, 2001') and the second ends (2002, 2002').

[0112] Furthermore, the electrode structure 1200 also includes a first single-function electrode 1250 and a second single-function electrode 1260. The first single-function electrode can only be connected by a contact through a first single contact 1251, and the second single-function electrode can only be connected by a contact through a second single contact 1261. The first single-function electrode 1250 and the second single-function electrode 1260 each have only one unique contact sufficient to apply a potential or excitation signal. To explicitly state that they each have only one unique contact, the contacts are referred to as "single contacts." This differs from the first multi-function electrode 1210 (see...). Figure 1A These conventional electrodes are also referred to as “single-function” for the purpose of explaining that they are not suitable for or constructed to perform specific electronic measurement and / or operational functions that exceed the simple application of the aforementioned potential or excitation signal.

[0113] The first single-function electrode 1250 extends circumferentially over the three sides of the first interdigital finger 1121, and the second single-function electrode is correspondingly arranged circumferentially on the three sides of the second interdigital finger 1122. Thus, the single-function electrodes can effectively participate in the excitation of the vibration of the interdigital fingers 1121 and 1122 in the excitation region 1120. For example, they can be used as the back potential or zero potential relative to the respective common excitation potential of the first and second multi-function electrodes 1210 and 1220 or the third and fourth multi-function electrodes 1230 and 1240.

[0114] piezoelectric resonator 1000 in Figures 1A to 3 The design shown is therefore suitable for implementing the previously mentioned method according to the second aspect of the invention, thereby achieving all the advantages mentioned in its context.

[0115] Furthermore, the piezoelectric resonator 1000 can be used as a component of the multivariable sensor 4000 in order to effectively realize the advantages mentioned in the context of the third aspect of the invention.

[0116] Such an exemplary design according to the third aspect of the present invention is Figure 4A The exemplary design of the multivariable sensor 4000 shown includes a piezoelectric resonator 1000 with a substrate 1100 and an electrode structure, and control electronics 4100 with a first switch 4110 and a second switch 4120, the first and second switches being electrically connected to a first main contact 1211 and a first auxiliary contact 1212 of a first multi-function electrode 1210 or to a second main contact 1221 and a second auxiliary contact 1222 of a second multi-function electrode 1220 of the electrode structure, respectively. The control electronics 4100 is electrically connected to a signal interface 4230 configured for communication and data exchange with a computer, control center, or similar device (not shown). The piezoelectric resonator 1000 may, in particular, have the features described above. Figures 1A to 3Features and design schemes in [the text].

[0117] The multivariable sensor 4000 has a housing 4200 with a process interface 4220 and a housing cavity 4210, wherein a seal 4221 is provided that seals the housing cavity 4210. The seal 4221 is constructed as a glass molded part, wherein a piezoelectric resonator 1000 is embedded in a through-hole of the seal 4221 by glass brazing such that when the multivariable sensor 4000 is coupled to a process, such as to an oil tank, via its process interface 4220, the excitation section 1120 extends from the seal and is in contact with the medium.

[0118] exist Figure 4B Another possible implementation of the multivariable sensor 4000 is shown. Regarding some features, such as the housing 4200, the housing cavity 4210, and the sealing of the housing 4200 relative to the piezoelectric resonator 1000 by means of the seal 4221, [the following is unclear and requires further context]. Figure 4A The implementation schemes are largely similar and partially identical.

[0119] Conversely, the piezoelectric resonator 1000 does not have two separate interdigitated fingers (as this is according to...). Figure 4A In contrast to the implementation scheme, it has a one-piece closed shape with substrate 1100; in other words, it depicts only a single interdigitated finger. In particular, the single interdigitated finger can correspond to its similar shape in... Figure 5 The implementation shown in the figure. This also applies to the implementation of the piezoelectric resonator 1000 that can be set here.

[0120] An electrode structure 1200 is arranged on the substrate 1100, which can be designed as a first, second, third, or fourth multifunctional electrode (1210, 1220, 1230, 1240). Accordingly, the multifunctional electrode may include a capacitor or a resistor rail. Wires on and / or within the substrate 1100 establish connections to two contacts, namely a first main contact 1211 and a first auxiliary contact 1212. Additional connections to the control electronics 4100 are established from the first main contact 1211 and the first auxiliary contact 1212, respectively. A first switch 4110 (as is also present in...) Figure 4A (As can be identified in the text) are considered optional features.

[0121] Figure 5 Another general embodiment of the piezoelectric resonator 1000 is schematically shown. The piezoelectric resonator 1000 includes a piezoelectric substrate 1100 with a base section 1110 and an excitation section 1120. The piezoelectric substrate 1100 is distinguished from... Figure 1A and 1B The implementation plan is constructed as a unique "cross finger".

[0122] In addition, an electrode structure 1200 is provided, which is at least partially arranged on or therein the excitation section 1120. The electrode structure 1200 includes a first multifunctional electrode 1210 having a first main contact 1211 and a first auxiliary contact 1212. According to... Figure 5 The above-described implementation scheme of the piezoelectric resonator can be used particularly in Figure 4B In the multivariable sensor described in [the text].

[0123] The prior description of the invention and the scope of the following claims are referred to herein as follows, namely, in Figure 1A , 1B The corresponding designations or names of the various multifunctional electrodes in 2A, 2B, 3, 4A, 4B, and 5 are purely exemplary and / or arbitrarily considered as the first multifunctional electrode 1210, the second multifunctional electrode 1220, the third multifunctional electrode 1230, or the fourth multifunctional electrode 1240. This means that virtually any other numbering, order, or designation is conceivable and possible. Accordingly, the multifunctional electrode of capacitor 3000 / 3000' is, for example, in... Figure 2A and 2B The exemplary design shown is not limited to the understanding that it must be the first multifunctional electrode 1210 or "the first multifunctional electrode 1210" and that the second, third or fourth multifunctional electrodes may also be designed in one of the forms shown.

[0124] This invention is not limited to the specific embodiments described above. Modifications may be made within the scope of the following claims. Similarly, features from the dependent claims may be combined with each other.

[0125] List of reference numerals

[0126] 1000 piezoelectric resonator

[0127] 1100 piezoelectric substrate

[0128] 1110 Basic Section

[0129] 1120 incentive section

[0130] 1121 First interdigitated finger

[0131] 1122 Second interdigitated finger

[0132] 1101 First Surface

[0133] 1102 Second Surface

[0134] 1200 electrode structure

[0135] 1210 First Multifunctional Electrode

[0136] 1211 First Main Contact

[0137] 1212 First Contact

[0138] 1220 Second Multifunctional Electrode

[0139] 1221 Second Main Contact

[0140] 1222 Second Contact

[0141] 1230 Third Multifunctional Electrode

[0142] 1231 Third Main Contact

[0143] 1232 Third contact

[0144] 1240 Fourth Multifunctional Electrode

[0145] 1241 Fourth Main Contact

[0146] 1242 Fourth Contact

[0147] 1250 First Monofunctional Electrode

[0148] 1251 First Single Contact

[0149] 1260 Second Monofunctional Electrode

[0150] 1261 Second Single Contact

[0151] 2000, 2000' resistance rails

[0152] 2001, 2001' First end

[0153] 2002, 2002' Second end

[0154] 3000, 3000' capacitors

[0155] 3001, 3001' First capacitor electrode

[0156] 3002, 3002' Second capacitor electrode

[0157] 3003 dielectric intermediate layer

[0158] 4000+ variable sensors

[0159] 4100 Control Electronic Device

[0160] 4110 First Switch

[0161] 4120 Second Switch

[0162] 4200 housing

[0163] 4210 Shell Inner Cavity

[0164] 4220 Process Interface

[0165] 4221 seal

[0166] 4230 signal interface

Claims

1. The piezoelectric resonator (1000) includes: - A piezoelectric substrate (1100) with a base section (1110) and an excitation section (1120), and - An electrode structure (1200) is arranged at least partially on or in the excitation section (1120). Its features are, The electrode structure (1200) includes a first multifunctional electrode (1210), which has a first main contact (1211) and a first auxiliary contact (1212).

2. The piezoelectric resonator (1000) according to claim 1, wherein, The electrode structure (1200) includes - A first single-function electrode (1250) with a first single contact (1251), and - A second single-function electrode (1260) with a second single contact (1261). Wherein, the first single-function electrode (1250) and the second single-function electrode (1260) are respectively at least partially arranged on or in the excitation section (1120), and The first multifunctional electrode (1210) is disposed on or in the base section (1110) and / or at least partially disposed on or in the excitation section (1120).

3. The piezoelectric resonator (1000) according to claim 1, wherein, The first multifunctional electrode (1210) is at least partially disposed on or within the excitation section (1120), and The electrode structure (1200) includes a first single-function electrode (1250) with a first single contact (1251), which is also at least partially disposed on or in the excitation section (1120).

4. The piezoelectric resonator (1000) according to claim 1, wherein, The first multifunctional electrode (1210) is at least partially disposed on or within the excitation section (1120), and The electrode structure (1200) includes a second multifunctional electrode (1220), which is also at least partially arranged on or in the excitation section (1120) and has a second main contact (1221) and a second auxiliary contact (1222).

5. The piezoelectric resonator (1000) according to claim 4, wherein, The first multifunctional electrode (1210) is at least partially disposed on or in the first surface (1101) of the piezoelectric substrate (1100), and The second multifunctional electrode (1220) is at least partially disposed on or in the second surface (1102) of the piezoelectric substrate (1100), the second surface being opposite to the first surface (1101).

6. The piezoelectric resonator (1000) according to claim 4 or 5, wherein, The electrode structure (1200) includes - A third multifunctional electrode (1230), which is also at least partially disposed on or in the excitation section (1120) and the third multifunctional electrode (1230) has a third main contact (1231) and a third auxiliary contact (1232), and - A fourth multifunctional electrode (1240), which is also at least partially arranged on or in the excitation section (1120) and the fourth multifunctional electrode (1240) has a fourth main contact (1241) and a fourth auxiliary contact (1242).

7. The piezoelectric resonator (1000) according to claim 6, wherein, The third multifunctional electrode (1230) is at least partially disposed on or in the first surface (1101) of the piezoelectric substrate (1100), and The fourth multifunctional electrode (1240) is at least partially disposed on or in the second surface (1102) of the piezoelectric substrate (1100), the second surface being opposite to the first surface (1101).

8. The piezoelectric resonator (1000) according to claim 6 or 7, wherein, The piezoelectric substrate (1100) has a tuning fork shape with at least two interdigits (1121, 1122), wherein the excitation section (1120) includes a first interdigit (1121) and a second interdigit (1122), and wherein - The first multifunctional electrode (1210) and the second multifunctional electrode (1220) are at least partially disposed in or on the first interdigital finger (1121), and - The third multifunctional electrode (1230) and the fourth multifunctional electrode (1240) are at least partially arranged in or on the second interdigital finger (1122).

9. The piezoelectric resonator (1000) according to any one of the preceding claims, wherein, The piezoelectric substrate (1100) is composed of or includes such a piezoelectric single crystal, particularly quartz or lithium niobate, and / or wherein the piezoelectric substrate (1100) is constructed in one piece.

10. The piezoelectric resonator (1000) according to any one of the preceding claims, wherein, The first multifunctional electrode (1210) includes - Resistance rails (2000, 2000') or - Capacitors (3000, 3000').

11. The piezoelectric resonator (1000) according to claim 10, wherein, The resistance rails (2000, 2000') - Has a temperature-dependent resistance, and / or - It has resistance, which depends on the concentration of the target medium in the environment surrounding the resistance rails (2000, 2000'), and / or - Constructed as a heating resistor, and / or - It has a zigzag shape, and / or Among them, the capacitors (3000, 3000') - Constructed as an interdigitated capacitor, or - It has a first capacitor electrode (3001) and a second capacitor electrode (3002), the second capacitor electrode (3002) being insulated from the first capacitor electrode (3001) through the piezoelectric substrate (1100) or a sublayer of the piezoelectric substrate (1100), or - It has a first capacitor electrode (3001) and a second capacitor electrode (3002), the second capacitor electrode (3002) being insulated from the first capacitor electrode (3001) by a dielectric interlayer (3003), wherein the dielectric constant of the dielectric interlayer (3003) depends on the concentration of the target medium in the environment surrounding the capacitor (3000, 3000').

12. The piezoelectric resonator (1000) according to any one of claims 4 to 8, wherein, The second multifunctional electrode (1220) includes - Resistance rails (2000, 2000') or - Capacitors (3000, 3000').

13. The piezoelectric resonator (1000) according to claim 12, wherein, The resistance rails (2000, 2000') - Has a temperature-dependent resistance, and / or - It has resistance, which depends on the concentration of the target medium in the environment surrounding the resistance rails (2000, 2000'), and / or - Constructed as a heating resistor, and / or - It has a zigzag shape, and / or Among them, the capacitors (3000, 3000') - Constructed as an interdigitated capacitor, or - It has a first capacitor electrode (3001) and a second capacitor electrode (3002), the second capacitor electrode (3002) being insulated from the first capacitor electrode (3001) through the piezoelectric substrate (1100) or a sublayer of the piezoelectric substrate (1100), or - It has a first capacitor electrode (3001) and a second capacitor electrode (3002), the second capacitor electrode (3002) being insulated from the first capacitor electrode (3001) through the dielectric intermediate layer (3003), wherein the dielectric constant of the dielectric intermediate layer (3003) depends on the concentration of the target medium in the environment surrounding the capacitor (3000, 3000').

14. The piezoelectric resonator (1000) according to any one of claims 6 to 8, wherein, The third multifunctional electrode (1230) and / or the fourth multifunctional electrode (1240) include - Resistance rails (2000, 2000') or - Capacitors (3000, 3000').

15. The piezoelectric resonator (1000) according to claim 14, wherein, The resistance rails (2000, 2000') - Has a temperature-dependent resistance, and / or - It has resistance, which depends on the concentration of the target medium in the environment surrounding the resistance rails (2000, 2000'), and / or - Constructed as a heating resistor, and / or - It has a zigzag shape, and / or Among them, the capacitors (3000, 3000') - Constructed as an interdigitated capacitor, or - It has a first capacitor electrode (3001) and a second capacitor electrode (3002), the second capacitor electrode (3002) being insulated from the first capacitor electrode (3001) through the piezoelectric substrate (1100) or a sublayer of the piezoelectric substrate (1100), or - It has a first capacitor electrode (3001) and a second capacitor electrode (3002), the second capacitor electrode (3002) being insulated from the first capacitor electrode (3001) by a dielectric interlayer (3003), wherein the dielectric constant of the dielectric interlayer (3003) depends on the concentration of the target medium in the environment surrounding the capacitor (3000, 3000').

16. A method for using the piezoelectric resonator (1000) according to any one of the preceding claims, comprising the following steps: - Step A: Perform electrical measurements on the first multifunctional electrode (1210) between the first main contact (1211) and the first auxiliary contact (1212), or The first multifunctional electrode (1210) is electrically controlled through the first main contact (1211) and the first auxiliary contact (1212), and - Step B: Apply an excitation signal to the first multifunctional electrode (1210) through the first main contact (1211), wherein, Either the same excitation signal is simultaneously applied to the first auxiliary contact (1212), or the first auxiliary contact (1212) is simultaneously electrically insulated from the excitation signal.

17. The method according to claim 16, wherein, The first multifunctional electrode (1210) has capacitors (3000, 3000'), and wherein The electrical measurements in step A include capacitance measurements and / or voltage measurements.

18. The method according to claim 16 or 17, wherein, The first multifunctional electrode (1210) has resistance rails (2000, 2000'), and wherein The electrical measurements in step A include resistance measurements.

19. The method according to any one of claims 16 to 18, wherein, The first multifunctional electrode (1210) has a heating resistor, and wherein The electrical operation in step A includes guiding heating current through the heating resistor via the first main contact (1211) and the first auxiliary contact (1212).

20. The method according to claim 19, wherein, - The electrode structure (1200) has a second multifunctional electrode (1220), which is also at least partially arranged on or in the excitation section (1120), and the second multifunctional electrode (1220) has a second main contact (1221) and a second auxiliary contact (1222), and - The second multifunctional electrode (1220) is constructed in the form of a parallel-plate capacitor, wherein the first capacitor electrode (3001) is insulated from the second capacitor electrode (3002) by a dielectric interlayer (3003), and the material forming the dielectric interlayer (3003) is selected such that the dielectric constant of the dielectric interlayer (3003) depends on the concentration of the target dielectric in the environment surrounding the capacitor (3000), and - The first multifunctional electrode (1210) is at least partially disposed on or in the first surface (1101) of the piezoelectric substrate (1100), and the second multifunctional electrode (1220) is at least partially disposed on or in the second surface (1102) of the piezoelectric substrate (1100), the second surface being opposite to the first surface (1101).

21. The method according to claim 19, wherein, - The electrode structure (1200) has a second multifunctional electrode (1220), which is also at least partially arranged on or in the excitation section (1120), and the second multifunctional electrode (1220) has a second main contact (1221) and a second auxiliary contact (1222), and - The second multifunctional electrode (1220) has a resistance rail (2000) with a resistance that depends on temperature, and - The first multifunctional electrode (1210) and the second multifunctional electrode (1220) are jointly arranged on one surface or in one surface of the piezoelectric substrate (1100), however, arranged in a laterally offset manner, and In step A - During the first time period T1, the heating current is guided through the heating resistor via the first main contact (1211) and the first auxiliary contact (1212), and immediately or at least partially simultaneously... - During time period T2, resistance measurement is performed on the resistance rail (2000) of the second multifunctional electrode (1220) between the second main contact (1221) and the second auxiliary contact (1222).

22. Multivariable sensor (4000), including - Piezoelectric resonator (1000) according to any one of claims 1 to 15. - Control electronics (4100), and - First switch (4110). in, The first switch (4110) is configured to, - In the first switching position, the first main contact (1211) and the first auxiliary contact (1212) are electrically connected to or provided to the control electronics (4100) separately from each other, and - In the second switch position, the first auxiliary contact (1212) is insulated from the control electronics (4100), and / or the first auxiliary contact (1212) is shorted from the first main contact (1211), wherein the first main contact (1211) is electrically connected to or provided to the control electronics (4100).

23. The multivariable sensor (4000) according to claim 22, wherein, The control electronics (4100) are configured to, - When the first switch (4110) is in the first switch position, an electrical measurement of the first multifunctional electrode (1210) is performed between the first main contact (1211) and the first auxiliary contact (1212) and provided as a first measurement signal and / or a first processed measurement value signal, and / or The first multifunctional electrode (1210) is electrically controlled through the first main contact (1211) and the first auxiliary contact (1212). as well as - When the first switch (4110) is in the second switch position, an excitation signal is applied to the first multifunctional electrode (1210) through the first main contact (1211), causing the first multifunctional electrode (1210) to participate in the vibration excitation of the excitation section (1120), and Then the excitation signal is turned off and the attenuation signal is received through the first main contact (1211) and provided as a second measurement signal and / or a second processed measurement value signal.

24. The multivariable sensor (4000) according to claim 23, wherein, - The first multifunctional electrode (1210) includes resistance rails (2000, 2000'). Wherein, when the first switch (4110) is in the first switch position, the control electronics (4100) is configured to, Resistance measurement of the resistance rails (2000, 2000') is performed between the first main contact (1211) and the first auxiliary contact (1212) and provided as a first measurement signal and / or a first processed measurement value signal, and / or A heating current or test current is directed through the resistance rails (2000, 2000') between the first main contact (1211) and the first auxiliary contact (1212), and / or - The first multifunctional electrode (1210) includes a capacitor (3000) with a first capacitor electrode (3001) and a second capacitor electrode (3002). The first capacitor electrode (3001) is connected to the first main contact (1211), and the second capacitor electrode (3002) is connected to the first auxiliary contact (1212). When the first switch (4110) is in the first switch position, the control electronics (4100) is configured to perform capacitance and / or voltage measurement of the capacitor (3000) between the first main contact (1211) and the first auxiliary contact (1212) and provide it as a first measurement signal and / or as a first processed measurement value signal.

25. The multivariable sensor (4000) according to any one of claims 22 to 24, wherein, The control electronics (4100) are configured to implement the method according to any one of claims 17 to 22.

26. The multivariable sensor (4000) according to any one of claims 22 to 25, comprising a housing (4200) with a process interface (4220) and a signal interface (4230), wherein, The process interface (4220) is sealed by a seal (4221), and The excitation section (1120) extends beyond the seal and is disposed outside the housing (4200), and The base section (1110) extends at least partially into the inner cavity (4210) of the housing.

27. The multivariable sensor according to claim 26, wherein, In particular, the seal (4221) is configured as a glass through-hole and the piezoelectric substrate (1100) is embedded in the glass through-hole.

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