Device and method for capacitive determination of the proportion of a substance in a material

Abstract

The invention relates to a device and a method for capacitive determination of the proportion of a substance in a material. The device comprises an oscillation circuit with a coil and a plate capacitor, wherein the oscillation circuit can be excited to oscillate at different frequencies or inductances. According to the invention, the frequency response or the resonance frequency of the oscillation circuit is recorded and evaluated with respect to characteristic features. On the basis of the frequencies which can be assigned to these characteristic features, the proportion of a particular substance in the material to be measured can be determined. The method for capacitive determination of the proportion of a substance in a material is based in particular on the fact that the dielectric properties of the substance are used in the method to determine the proportion of the substance in the material to be measured.

Description

Technical Field

[0001] This invention relates to an apparatus and method for capacitively determining the proportion of a substance in a material. The apparatus includes an oscillating circuit having a coil and a plate capacitor, wherein the oscillating circuit can be excited to oscillate at different frequencies or inductances. According to the invention, the frequency response or resonant frequency of the oscillating circuit is recorded and evaluated regarding characteristic features. Based on the frequencies that can be assigned to these characteristic features, the proportion of a specific substance in the material to be measured can be determined. The method for capacitively determining the proportion of a substance in a material is specifically based on the fact that the dielectric properties of the substance are used in this method to determine the proportion of the substance in the material to be measured. Background Technology

[0002] It is known in the art that the concentration or proportion of a substance in a material to be examined can be determined by optical methods. In these conventional methods known from the art, specifically, the optical properties of the substance whose proportion is to be determined are used to determine that proportion. Many optical methods are based on the fact that the substance whose proportion is to be determined is dissolved in a liquid, and the resulting solution is irradiated. The optical response to the irradiation is recorded and plotted in the form of a spectrum. The concentration of the substance can then be inferred from the spectrum of the absorbed and / or reflected radiation.

[0003] For example, such an optical measurement method is described in DE 41 22 925 A1. The invention described in the aforementioned patent application relates to an optical spectrometer having an irradiation device coupled to at least one optical waveguide for irradiating a substance to be spectroscopically examined, contained in a measurement sample chamber. The spectrometer includes a monochromator device and a detector arrangement. A disadvantage of the optical method described in DE 41 22 925 A1 is the necessity of using optical components to determine concentration. However, the use of optical components often results in high costs and considerable sensitivity of the acquired measurement equipment, making it unusable outside of a protected laboratory atmosphere. In this respect, in reality, and specifically in locations with high potential for vibration, noise, and / or contamination, such as construction sites, the use of optical methods and devices based on such methods is, even if possible, highly limited.

[0004] Furthermore, optical methods have the disadvantage that a liquid is always required to dissolve the substance to be measured. However, in some cases, such (preferably clean) solvent liquids are not always available. Specifically, the liquid needs to be examined to determine the refractive index transition or change between the optical measurement system and the sample. Due to the requirement for a solvent liquid, it is impossible, for example, to determine the proportion of a substance in a non-liquid-soluble substance or in air using optical methods.

[0005] Therefore, the objective of this invention is to overcome the shortcomings and defects of the prior art described above and to provide an apparatus and method for capacitively determining the proportion of substances in a material. Experts would welcome improvements to the method and apparatus if they could also be used to determine the proportion of substances in insoluble materials and if measurements could also be taken in air. It is also intended that the provided apparatus be usable in harsh environments (such as construction sites), where vibration and severe contamination are typically expected. Specifically, a robust, stable, and insensitive apparatus is intended. Another concern is making the provided method inexpensive and easy to use.

[0006] This objective is achieved through the subject matter of the independent claim. Advantageous embodiments relating to the subject matter of the independent claim can be found in the dependent claims. Summary of the Invention

[0007] According to the present invention, an apparatus for capacitively determining the proportion of substances in a material is provided, the apparatus comprising an oscillating circuit having a coil and a plate capacitor. The apparatus is characterized in that the plate capacitor can be filled with the material as a dielectric, and the frequency response of the dielectric is recorded and evaluated to determine the proportion of substances in the material.

[0008] In a second aspect, the present invention relates to a method for capacitively determining the proportion of substances in a material. The method is characterized by the following steps:

[0009] a) Provide the proposed apparatus.

[0010] b) Fill the plate capacitor of the device with the material, wherein the proportion of substances in the material will be determined.

[0011] c) Different frequencies or inductors are set in the oscillation circuit of the device.

[0012] d) Record the frequency response or resonant frequency of the material.

[0013] e) Evaluate the frequency response or these resonant frequencies by searching for characteristic features.

[0014] f) Use the characteristic frequency fc that can be assigned to these characteristic features to determine the proportion of the substance.

[0015] One application area of ​​this invention is determining the proportion of quartz in dust samples. The quartz content in the dust to be measured is important information because quartz is associated with diseases such as silicosis or lung cancer. As many countries are making increasing efforts to better protect workers at mining or construction sites from high levels of dust exposure and the resulting negative health effects, there is great interest in practical, realistic, and cost-effective technical solutions for dust inspection. Experts would particularly welcome any possible method that can quickly and reliably determine the quartz content in the dust to be measured, enabling appropriate protective measures for the workers involved.

[0016] Therefore, it is conceivable to use the proposed device as a "dust dosimeter," which can be carried by workers on construction sites to determine the amount of quartz they are exposed to throughout the day. By analogy with a radiation dosimeter, the proposed device can record and store the acquired data or transfer this data to another device for further processing. For the purposes of this invention, it may also be preferred that the proposed device emit optical and / or acoustic warning signals, for example, indicating to workers that they have reached or are about to reach their maximum daily quartz exposure. For the purposes of this invention, it may also be preferred that the device be arranged on a vacuum cleaner or air purifier so that the quartz content in the dust in the area surrounding the vacuum cleaner or air purifier can be determined. Furthermore, for the purposes of this invention, it may be preferred that the device be used in the area surrounding or on a dust-generating device, such as a power tool, to directly examine the composition of the dust at its origin and specifically determine the quartz content.

[0017] One advantage of the proposed method and apparatus is that they eliminate the need for expensive and sensitive optical elements and measuring equipment. Therefore, the present invention provides an inexpensive and insensitive technical solution for determining the proportion of matter in a material (preferably dust) to be measured. This is specifically achieved by capacitively performing the method and apparatus for determining the proportion of matter, and by using the dielectric properties of the matter whose proportion is to be determined to determine the proportion of matter in the dust. For the purposes of the invention, it is particularly preferred that the determination of the proportion of matter in the dust occurs capacitively.

[0018] For the purposes of this invention, it is particularly preferred that, within the context of the proposed method, the dielectric properties or dielectric constant of the material to be measured are measured at different frequencies to determine the quartz content in the dust sample. Specifically, the spectrum is measured to obtain and evaluate the dielectric response of the dust sample. For the purposes of this invention, it is preferred that, at the start of the method, a short pulse or falling edge is applied to the electromagnetic oscillation circuit of the device.

[0019] For the purposes of this invention, it is preferable to charge the capacitor with short pulses of known energy or voltage. After the capacitor has been charged, the energy or voltage is suddenly removed, for example, by means of a short circuit, such as across a coil of an electromagnetic oscillating circuit. For the purposes of this invention, it is preferable that the excitation of the oscillating circuit can be performed similarly. Preferably, when the plate capacitor is being charged or when the oscillating circuit is being excited, the excited harmonic components are selected or set at frequencies that cause them to be set to excite the quartz resonance.

[0020] In response to this, the oscillating circuit begins to oscillate at its resonant frequency. Preferably, this resonant frequency can be recorded using the device's control unit. The frequency can also be adjusted using diodes, capacitors, and / or potentiometers until a frequency associated with quartz is reached. The dielectric property or dielectric constant of the material to be measured can be determined based on a value set for the inductor L. For the purposes of this invention, it is preferred that, for example, the quartz content in dust is related to the change in the dielectric property or dielectric constant of the dust within the resonant frequency range. In other words, the applicable relationship is: "The greater the change in dielectric property or dielectric constant at the resonant frequency, the more quartz is contained in the dust."

[0021] Another advantage of this invention is that it can also measure materials insoluble in water or liquids. Specifically, the proposed method and apparatus allow for the determination of the proportions of substances in the air. Therefore, a specific advantage of this invention is that capacitive measurements can be performed using mechanically insensitive components and without requiring a liquid solution medium.

[0022] In the context of this invention, an apparatus comprising an oscillating circuit having a coil and a plate capacitor is provided. For the purposes of this invention, the apparatus is provided configured to perform the proposed method. The coil is preferably a conductive coil, the properties of which are preferably described by inductance L. For the purposes of this invention, it is preferred that the coil to be used and the properties of the coil, together with the plate capacitor, are selected depending on the substance to be detected or the material to be measured and on the properties of the plate capacitor, which together form the oscillating circuit of the proposed apparatus. For example, a value of approximately 100 μH can be selected as the starting point for operating the oscillating circuit. Those skilled in the art will understand that this value can vary by several orders of magnitude specifically with the size of the apparatus.

[0023] For the purposes of this invention, it is preferred that the plate capacitor comprises two plates between which a voltage can be applied. Two alternative methods can be used to perform the proposed method. According to the first method, a sinusoidal excitation signal can be applied to the oscillating circuit of the device (“sinusoidal sweep”), preferably using a constant voltage amplitude. In response to this excitation, the voltage drop across the capacitor is recorded, as if the electromagnetic oscillating circuit were a voltage divider. According to this first method, the voltage is recorded as a measured variable within a predetermined frequency, which can produce a voltage-frequency diagram. Figure 2 Such a diagram is shown as an example.

[0024] This first method can be described through the following steps:

[0025] a) Provide the proposed apparatus.

[0026] b) Fill the plate capacitor of the device with the material, wherein the proportion of substances in the material will be determined.

[0027] c) Set different frequencies in the oscillation circuit of the device.

[0028] d) Record the frequency response of the material.

[0029] e) Evaluate the frequency response by searching for characteristic features.

[0030] f) Use the characteristic frequency fc that can be assigned to these characteristic features to determine the proportion of the substance.

[0031] According to the second method, an electromagnetic oscillation circuit in which inductors L of different sizes can be set or "looped" is provided. In this second method, different inductors L represent specified variables. The electromagnetic oscillation circuit is then excited to oscillate, and the resonant frequency is recorded as the measured variable and / or plotted relative to the inductance. A frequency-inductance diagram is thus obtained. In the context of this second method, it is preferable that the electromagnetic oscillation circuit is designed such that when the first inductor is set, the electromagnetic oscillation circuit oscillates at a first resonant frequency of the quartz. This design is specifically achieved by setting a specific measurement inductor as a specified variable. Measurements can then be repeated for different inductors that can be looped in the oscillation circuit, during which the oscillation circuit preferably oscillates at a second or other resonance of the quartz.

[0032] This second method can be described by the following steps:

[0033] a) Provide the proposed apparatus.

[0034] b) Fill the plate capacitor of the device with the material, wherein the proportion of substances in the material will be determined.

[0035] c) Set different inductors in the oscillation circuit of the device.

[0036] d) Record the resonant frequency of the material.

[0037] e) Evaluate the resonant frequency by searching for characteristic features.

[0038] f) Use the characteristic frequency fc that can be assigned to these characteristic features to determine the proportion of the substance.

[0039] For the purposes of this invention, it is preferable to use a sufficiently large voltage amplitude to excite the oscillating circuit. For the purposes of this invention, if the voltage amplitude is set to excite resonance in the oscillating circuit, then the voltage amplitude is considered "sufficiently large".

[0040] The plates of the plate capacitor are preferably substantially parallel to each other. For the purposes of this invention, it is preferred that the plate capacitor includes connections for a voltage source and / or for a control unit. The parameters of the plate capacitor or its plates can preferably be selected depending on the substance to be detected or the material to be measured. For example, these parameters are the size of the plates of the plate capacitor or the distance between the plates. The geometric parameters of the plate capacitor preferably define the volume of dust to be measured that can be filled therein as a dielectric.

[0041] For the purposes of this invention, it is preferred that the material being measured and introduced into the measuring volume between the plates of the plate capacitor is preferably referred to as the "material to be measured". In a particularly preferred exemplary embodiment of the invention, the material to be measured is dust. For example, such dust may be present at construction sites, specifically when substrates such as walls, concrete, and limestone are processed with power tools such as core drills, saws, angle grinders, or cutting grinders or hammer drills, but not limited to these applications. Specifically, concrete or masonry may contain quartz, so that quartz-containing dust may be generated when processing such substrates. The inventors have recognized that the densities of concrete and quartz are approximately similar or equivalent, making this fact usable for capacitive determination of the quartz content in a dust sample.

[0042] In the context of this invention, the substance whose proportion is to be determined in the material to be measured is referred to as the "substance whose proportion is to be determined". In a particularly preferred exemplary embodiment of the invention, the substance whose proportion is to be determined is quartz. Quartz has the chemical composition SiO2 and specifically takes the form of a crystal lattice structure. Due to the structure of quartz, it can be polarized, and the polarization of the substance allows for a clear identification of the substance if the dielectric constant of the substance is measured and evaluated at a characteristic frequency. For the purposes of this invention, the relevant characteristic frequency of quartz is in the range of 10. 4 Hz to 10 6The range is Hz (i.e., approximately 10 kHz to 1000 kHz), and electrical measurements can be performed at these frequencies without any problems. The inventors have recognized that the dielectric properties of a material (specifically quartz) can be used to determine the proportion of the substance in a material to be measured (e.g., dust).

[0043] In the context of this invention, dust, which is the material to be measured, is introduced as the dielectric between the plates of a plate capacitor. The properties of the plate capacitor can preferably be described using the capacitance C of an electromagnetic oscillation circuit that is part of the proposed apparatus.

[0044] In the next step, different frequencies are set in the electromagnetic oscillation circuit of the device.

[0045] In other words, different frequencies can be applied to the oscillating circuit. For the purposes of this invention, it is preferred that the device includes a voltage source configured to excite the oscillating circuit to oscillate. In other words, the oscillation of the oscillating circuit can be implemented by the voltage source, preferably matching the voltage to be provided by the inductance L of the coil, the capacitance C of the capacitor, and the material properties of the material to be measured and the substance whose proportion is to be determined. In other words, the voltage to be provided by the voltage source is selected based on the variables just mentioned. For example, the material properties of the material to be measured and the substance whose proportion is to be determined can be density, dielectric constant, etc. For the purposes of this invention, it is specifically preferred that the determination of the proportion of the substance in the dust is capacitively generated.

[0046] For the purposes of this invention, it is preferable that the frequency applied to the dielectric or plate capacitor (i.e., the frequency being measured) is in the range of 0 kHz to 1000 kHz, preferably in the range of 10 kHz to 800 kHz, and most preferably in the range of 100 kHz to 500 kHz. These frequency ranges are particularly advantageous and suitable for determining the proportion of quartz in dust, since the characteristic frequency response of quartz in a particular testing apparatus is, for example, approximately 150 kHz and 250 kHz. Those skilled in the art will recognize that the specified values ​​can depend on the size, geometry, and / or moisture content of the material to be measured; this is why, for the purposes of this invention, it is preferable to perform calibrated measurements using the measuring apparatus to be used in order to, for example, determine the location of the characteristic frequencies. For the purposes of this invention, it is preferable that these frequencies are the resonant frequencies of the oscillating circuit, to transmit these resonant frequencies by applying different variables to the oscillating circuit or its components. For the purposes of this invention, it is preferable that the resonant frequencies of the electromagnetic oscillating circuit can be recorded or measured by a control unit, as further explained below, wherein the control unit may be part of the proposed device. The control unit is preferably configured as a microcontroller. For the purposes of this invention, it is also preferable that the quality of the electromagnetic oscillating circuit is measured by the control unit. For this purpose, the voltage drop across the coil and capacitor, as well as the phase angle, are measured and evaluated by a microcontroller.

[0047] For the purposes of this invention, it is preferable that the mass of the electromagnetic oscillation circuit can be used as a correction variable to eliminate measurement errors that may occur when the resonant frequencies of different substances whose proportions in the material are to be determined are very similar or within similar ranges. In addition to measuring the dielectric properties or dielectric constant of the material at a specific frequency, the mass of the electromagnetic oscillation circuit can also preferably be used to distinguish the resonant frequencies of the first and second substances from each other.

[0048] For the purposes of this invention, it is particularly preferred that the electromagnetic oscillation circuit of the proposed device is excited to oscillate at different frequencies, wherein the frequency response of the dielectric (i.e., the dust to be measured) is subsequently recorded and evaluated to determine the proportion of the substance whose proportion is to be determined in the dust. For the purposes of this invention, these steps are preferably also referred to as “setting different frequencies in the oscillation circuit of the device” and “recording the frequency response of the dust”.

[0049] For the purposes of this invention, it is preferred that the device includes a control unit configured to record the frequency response of the dielectric. The control unit of the device is preferably configured as a microcontroller. The control unit is preferably a freely programmable processor that can have integrated peripheral functions. For the purposes of this invention, the control unit is specifically configured to control the sensors and / or recording devices of the proposed device. The control unit may also be configured to store and / or evaluate the measured values ​​recorded by the sensors and / or recording devices.

[0050] In the context of this invention, a microcontroller is used to record and evaluate the frequency response of the dust to be measured. Specifically, the voltage between the plates of a plate capacitor is measured and plotted against different frequencies, thereby obtaining a frequency-voltage plot (see...). Figure 2 ).

[0051] For the purposes of this invention, it is preferable that the control unit is also configured to apply different frequencies to the dielectric. This can be achieved, for example, by enabling the control unit to turn the voltage on or off. For the purposes of this invention, it may also be preferable that the electromagnetic oscillation circuit is excited by a voltage source. For the purposes of this invention, it is most preferable to use a voltage source controlled by the control unit to excite the electromagnetic oscillation circuit or apply different frequencies to the dielectric.

[0052] In other words, the microcontroller can also be used to apply different frequencies to the electromagnetic oscillation circuit of the proposed device, and in the context of this invention, to record and evaluate the dielectric's response to different frequencies in order to determine the proportion of substances in the dust.

[0053] For the purposes of this invention, it is particularly preferred that the response of the material to be measured be recorded in the form of voltage. For example, the frequency response of a dielectric (i.e., the material to be measured) can be plotted as a frequency-voltage graph. The frequency applied to or used to excite the oscillating circuit is plotted on the x-axis of the graph, while the frequency response of the dust is plotted on the y-axis. The frequency response of the material to be measured can then be evaluated by searching for characteristic features in the graph. Specifically, characteristic features of the curves in the frequency-voltage graph can be examined. According to an alternative second method, a frequency-inductance graph can preferably be evaluated. In other words, characteristic peaks can be searched in the frequency-voltage graph, which are specifically determined by the characteristic frequency fc of the particular material. For the purposes of this invention, this preferably means that different substances in the material to be measured can be identified by the location of characteristic features in the frequency-voltage graph. For example, such peaks for quartz are at frequencies approximately 150 kHz and 250 kHz. In other words, in the context of this invention, if a peak or anomaly appears at frequencies approximately 150 kHz and 250 kHz in the frequency-voltage graph representing the frequency response of the dust, it can be inferred that quartz is present in the dust sample to be measured. For the purposes of this invention, it is preferred that, in the case of crystalline materials, the characteristic frequency fc is typically generated by the lattice structure of the material. In a preferred exemplary embodiment of the invention, this results in characteristic frequencies fc1≈150kHz and fc2≈250kHz when the desired proportion of quartz in a dust sample is determined.

[0054] For the purposes of this invention, it is preferable to achieve greater frequency variation by setting inductances of different sizes, where the inductance describes the properties of the coil in the oscillating circuit. For example, relays, analog switches, and / or gyroscope circuits can be used to set different inductance sizes. Tests have shown that, for example, analog switch or gyroscope circuits are particularly insensitive to vibration. Therefore, for the purposes of this invention, it is therefore preferable that the device includes relays, analog switches, and / or gyroscope circuits for setting different frequencies in the oscillating circuit. Preferably, in this way, the inductance of the coil in the oscillating circuit can be changed, and the change in the coil's inductance advantageously causes a change in the frequency of the oscillating circuit. For example, different inductance settings can be performed by connecting an electric ring to the coil of the oscillating circuit.

[0055] For the purposes of this invention, it is preferable to achieve small frequency variations by using capacitors of different sizes; for example, the capacitors describe the properties of a capacitor diode that can be connected in series or parallel with a plate capacitor in an oscillating circuit. For the purposes of this invention, it is preferable that the device includes capacitor diodes for setting different frequencies in the oscillating circuit, and these capacitor diodes can be connected in series or parallel with a plate capacitor in the oscillating circuit. Therefore, for the purposes of this invention, it is preferable that the capacitance of the capacitor diodes can be used to set different frequencies in the oscillating circuit. Depending on the desired frequency change sign within the oscillating circuit, the capacitor diodes can be connected in series or parallel with a plate capacitor in the oscillating circuit. For the purposes of this invention, it is preferable that the capacitor diodes represent electrically controlled capacitors, the control of which preferably occurs by means of a control unit.

[0056] For the purposes of this invention, it is preferable that the variable inductance of the coil and the capacitance of the diode are set by the control unit. This process is also preferably referred to as looping. By setting different inductances and capacitances, the (resonant) frequency of the electromagnetic oscillation circuit of the proposed device changes and different frequencies are applied to the material to be measured. By means of the properties of the dielectric material and / or the properties of the substance whose proportion is to be determined, the desired proportion of the substance can therefore be determined based on the electrical parameters of the electromagnetic oscillation circuit.

[0057] The inventors have recognized that the relative permittivity or dielectric constant of the material to be measured is approximately proportional to the quartz content in the material of the capacitor or the volume of dust. Therefore, if, for example, the dielectric constant measured when measuring dust without quartz is 1, and the dielectric constant measured when measuring a material with a high quartz content (almost 100%) is 5, then when measuring dust with an unknown quartz content, a dielectric constant of 3 can be used to infer that the quartz content in this dust sample is in the range of approximately 50%. This assignment is also based on the knowledge that quartz and concrete have similar densities. This determined quartz proportion can advantageously be correlated with the volume of air from which the dust sample is extracted or filtered, in order to determine, for example, the quartz content in the breathable air of workers at a construction site.

[0058] For the purposes of this invention, it is preferable to induce frequency changes by setting different inductances, where the inductance describes the properties of the coil in the oscillation circuit of the device. For example, a relay can be used to set inductances of different sizes. For the purposes of this invention, it is also preferable to induce frequency changes by setting different capacitances, where the capacitance describes the properties of a capacitor diode that can be connected in series or parallel with a plate capacitor in the oscillation circuit.

[0059] In an exemplary embodiment, the present invention relates to a sensor device for determining the proportion of a substance in dust, the sensor device having a plate capacitor that can be filled with dust as a dielectric, measuring and evaluating the frequency response or spectral shift of the dielectric to determine the proportion of the substance in the dust. For the purposes of the invention, the substance to be determined in proportion to the dust is quartz. Information regarding the proportion of quartz in a dust sample is of great interest because quartz is considered to have health-damaging properties.

[0060] For the purposes of this invention, it may also be preferred that the capacitor is not necessarily filled with the material to be measured, but rather that the capacitor measures the material from one side. The material to be measured can be spatially close to the plate capacitor, and the material to be measured can cause changes in the measured variable that can be recorded by the capacitor. These changes can be detected and evaluated using this capacitive measurement method.

[0061] In a further exemplary embodiment of the invention, it is preferred to use an electromagnetic oscillation circuit with a variable frequency for measurement, wherein the resonant frequency, mass, and voltage drop of the electromagnetic oscillation circuit are measured via a coil and a capacitor. Additionally, different inductors and capacitors can be used to adjust the resonant frequency of the electromagnetic oscillation circuit. For the purposes of the invention, it is preferred to use a plate capacitor to perform the proposed method for determining the proportion of a substance by introducing the material to be measured (here, a dust sample) between the plates of the plate capacitor.

[0062] For the purposes of this invention, it is preferable to use a second electromagnetic oscillation circuit whose waveform can be superimposed on the waveform of the previously used plate capacitor to improve the measurement.

[0063] In other words, in the context of the proposed apparatus, it may be preferable that the apparatus includes a second oscillation circuit whose measurements can be superimposed on those of the first oscillation circuit in order to further improve the accuracy and reliability of the determination method and apparatus.

[0064] The provision of the second electromagnetic oscillation circuit takes into account the knowledge that the "ideal" frequency of the oscillation circuit may deviate from the actual frequency. This could be due to factors such as air humidity or thermal expansion of the plate capacitor, but this list is not exhaustive. Therefore, a second electromagnetic oscillation circuit not filled with dust can be used. For the purposes of this invention, it is preferable to excite the first and second oscillation circuits in substantially the same manner and substantially simultaneously. Depending on the phase shift between the oscillation circuits, the maximum sum of the voltage values ​​of the two oscillation circuits is twice the voltage value of one of the two oscillation circuits, or the voltages cancel each other out, resulting in a total voltage of 0V. If the first electromagnetic oscillation circuit is filled with the material to be measured, the oscillation frequency of the first electromagnetic oscillation circuit preferably varies. There is interference between the preferred waveform voltage curves, and the jumping frequencies of the two oscillation circuits are advantageously proportional to the quartz content of the material in the plate capacitor filled into the first oscillation circuit. A key advantage of this embodiment of the invention is that any influence of air humidity or temperature is not within the scope of the evaluation of the interference value or the jumping of the two oscillation circuits, and the quartz content thus determined is not falsified.

[0065] Further advantages will become apparent in the following description of the accompanying drawings. The drawings, description, and claims contain numerous combinations of features. Those skilled in the art will also readily consider these features individually and combine them to form further useful combinations. Attached Figure Description

[0066] In the accompanying drawings, identical and similar parts are indicated by the same reference numerals. In the accompanying drawings:

[0067] Figure 1 A schematic diagram of a preferred embodiment of the device is shown;

[0068] Figure 2 The graphs showing the recorded voltage versus different frequencies are shown, and these different frequencies can be set in an oscillating circuit to determine the desired proportions of the material. Detailed Implementation

[0069] Figure 1A schematic diagram of a preferred embodiment of device 1 is shown. Device 1 includes an electromagnetic oscillation circuit 2, which in turn includes a coil L and a capacitor C. The capacitor C is formed as a plate capacitor. The plate capacitor preferably has two plates with an electric field between them. Materials such as dust can be filled into the volume formed between the plates of the plate capacitor. For the purposes of this invention, it is preferable to examine the constituent substances of such material and the proportions of these substances in the material.

[0070] Different frequencies can be applied to the oscillation circuit 2. Corresponding oscillations are then excited by the voltage source 3. The voltage source 3 is preferably configured as a frequency generator or a sine wave generator. For the purposes of this invention, it is also preferable that the control unit 4 and the voltage source 3 form a single unit.

[0071] Furthermore, device 1 may include a control unit 4, preferably configured as a microcontroller. For the purposes of this invention, it is preferred that the control unit 4 be configured to record the frequency and quality of the oscillation circuit 2. Furthermore, the control unit 4 may be configured to electrically set or "loop" the capacitors and inductors of the oscillation circuit 2. For the purposes of this invention, it is preferred that the control unit 4 include means for voltage measurement, for example, the means may be configured as an oscilloscope with integrated options for performing a fast Fourier transform. For the purposes of this invention, it is particularly preferred that the control unit 4 is specifically designed to perform frequency measurement.

[0072] The oscilloscope is preferably configured to record the amplitude of the frequency across capacitor C. For the purposes of this invention, it is preferred that, in the proposed method, the amplitude of the frequency across capacitor C represents the measured variable. Particularly preferred for the purposes of this invention is that the amplitude is recorded within a sinusoidal frequency range. This preferably means exciting the electromagnetic oscillation circuit 2 with a preferably sinusoidal excitation signal that can be generated by a frequency generator. The peak value of the voltage across the empty capacitor C is then compared with the peak value of the capacitor C filled with dust-containing quartz. The resonant frequency can be determined by the position of the peak value in a frequency-inductance diagram or a voltage-frequency diagram.

[0073] Figure 2 The graphs showing the recorded voltage versus different frequencies are shown. These different frequencies can be set in the oscillating circuit 2 to determine the desired proportion of the substance. Figure 2 The upper part a) shows the voltage-frequency diagram for dust-free quartz, while Figure 2 The lower part b) shows the voltage-frequency diagram of dust containing quartz. In other words, Figure 2 The material to be measured in the upper part a) is free of quartz dust, and Figure 2The material to be measured in the lower part b) is dust containing quartz. On the x-axis of the voltage-frequency graph, the frequency or resonant frequency f of the oscillating circuit is plotted in kilohertz (kHz), while on the y-axis of the voltage-frequency graph, the voltage U recorded by the control unit 4 is plotted in volts (V). Figure 2 The graph shown allows for the evaluation of frequency response by searching for characteristic features, as proposed using a voltage-frequency graph according to the first evaluation method. Specifically, the characteristic frequency fc, which can be assigned to the characteristic feature, is used to determine the proportion of the material.

[0074] Figure 2 The lower part b) clearly shows the characteristic frequencies fc1 and fc2, which are approximately 150 kHz and 250 kHz. The positions of these characteristic frequencies fc1 and fc2 indicate the presence of quartz in the dust being examined, which is used to fill the plate capacitor C of device 1. Figure 2 In the example of the invention shown, quartz is the substance whose proportion is to be determined in the material to be measured (here, dust).

[0075] List of reference numerals

[0076] 1 device

[0077] 2. Oscillating Circuit

[0078] 3 Voltage Source

[0079] 4 Control Unit

[0080] L coil

[0081] C capacitor

Claims

1. An apparatus (1) for capacitively determining the proportion of quartz in a material, the apparatus comprising an oscillating circuit (2) having a coil L and a plate capacitor C. Its features are, The plate capacitor C can be filled with the material as a dielectric, wherein the device (1) is configured to record and evaluate the frequency response of the dielectric in order to determine the proportion of quartz in the material, wherein the device (1) is configured to set different frequencies.

2. The apparatus (1) as described in claim 1. Its features are, The device (1) is configured to determine the proportion of quartz in the material by means of capacitance.

3. The apparatus (1) as described in claim 1 or 2. Its features are, The device (1) includes a voltage source (3) configured to excite the oscillation circuit (2) to oscillate.

4. The apparatus (1) as described in claim 1 or 2. Its features are, The device (1) includes a control unit (4) configured to record the frequency response of the dielectric.

5. The apparatus (1) as described in claim 4. Its features are, The control unit (4) is also configured to apply different frequencies to the dielectric.

6. The apparatus (1) as described in claim 5. Its features are, The frequency applied to the dielectric is in the range of 0 kHz to 1000 kHz.

7. The apparatus (1) as described in claim 6. Its features are, The frequency applied to the dielectric is in the range of 10 kHz to 800 kHz.

8. The apparatus (1) as described in claim 6. Its features are, The frequency applied to the dielectric is in the range of 100 kHz to 500 kHz.

9. The apparatus (1) as described in claim 1 or 2. Its features are, The device (1) includes capacitor diodes for setting different frequencies in the oscillation circuit (2).

10. The apparatus (1) as claimed in claim 9. Its features are, These capacitors and diodes can be connected in series or in parallel to the plate capacitor of the oscillating circuit (2).

11. The apparatus (1) as described in claim 1 or 2. Its features are, The device (1) includes relays, analog switches and / or gyroscope circuits for setting different frequencies in the oscillation circuit.

12. A method for capacitively determining the proportion of quartz in a material, Its features The following are the steps: a) Provide an apparatus (1) as described in any one of the preceding claims. b) Fill the plate capacitor C of the device (1) with the material, wherein the proportion of quartz in the material will be determined. c) Different frequencies or inductors are set in the oscillation circuit (2) of the device (1). d) Record the frequency response or resonant frequency of the material. e) Evaluate the frequency response or these resonant frequencies by searching for characteristic features. f) Use the characteristic frequency fc that can be assigned to these characteristic features to determine the proportion of the quartz.

13. The method as described in claim 12, Its features are, In this method, the dielectric properties of quartz are used to determine the proportion of quartz in the material.

14. The method as described in claim 12 or 13, Its features are, These frequency changes are caused by setting different inductors, which describe the properties of the coil L of the oscillating circuit (2) of the device (1).

15. The method as described in claim 12 or 13, Its features are, These frequency variations are caused by setting different capacitors, which describe the properties of the capacitor diode and / or the plate capacitor C of the oscillating circuit (2).

16. The method as described in claim 12 or 13, Its features are, The material includes dust.

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