Patent Application
20240418690
The invention relates to a detection unit for a gas sensor, to a gas sensor, to a system for detecting a plurality of different target gases, and to a method for detecting a target gas.
Gas sensors are used to detect and analyze gases. Gas sensors with physical and chemical measurement principles are known. The present invention relates to colorimetric gas sensors, in which a gas-sensitive element comprises at least one gas-sensitive material that varies its optical properties as a function of the contact with a target gas. Such colorimetric gas sensors are used in particular when only a limited energy supply is available and/or the intention is to provide economical sensors.
Colorimetric gas sensors in which the detection of the target gas takes place by means of analyzing ambient light that passes through the gas-sensitive element of gas sensor are known. Such a gas sensor is known from EP 3 783 341 A1.
There is a need for economical gas sensors that can be employed by users who do not have professional access to measuring instruments specially developed for gas sensing technology. Particularly in the private sector, the demand for sensors to monitor environmentally critical and noxious gases is increasing greatly.
The object of the present invention is therefore to provide an economical means of gas detection. This object is achieved by a detection unit for a gas sensor, by a gas sensor comprising such a detection unit, by a system for detecting a plurality of different target gases, and by a method for detecting a target gas, each having one or more of the features disclosed herein. Advantageous configurations may be found in in the description and claims that follow.
The detection unit according to the invention, the gas sensor according to the invention and the system according to the invention for detecting a plurality of different target gases are preferably configured to carry out the method according to the invention, in particular a preferred embodiment thereof.
The method according to the invention is preferably configured to be carried out by means of a detection unit according to the invention, by means of a gas sensor according to the invention or by means of a system according to the invention for detecting a plurality of different target gases, in particular by means of preferred embodiments of these apparatuses.
The present invention is based on the discovery that mobile devices comprising an image acquisition unit are very widespread and may be used economically to detect a target gas. In particular, cellphones typically not only have image acquisition units that enable image acquisition with high quality, in particular good color rendering. Such devices furthermore have computer units and data memories that provide sufficient computing power to analyze the image data of the image acquisition unit by means of provided third-party programs (applications, “apps”).
In the present invention, such devices are used and supplemented with a detection unit in order to detect one or more target gases.
The object mentioned in the introduction is therefore achieved by a detection unit having one or more of the features disclosed herein:
The detection unit according to the invention for a gas sensor has at least one gas-sensitive element comprising at least one gas-sensitive material, the optical properties of which vary as a function of the contact with a target gas.
Such gas-sensitive materials are known from the prior art and in particular from EP 3 783 341 A1.
What is essential is that the detection unit is configured for removable arrangement on a mobile evaluation unit comprising an image acquisition unit, in order to form a gas sensor. The image acquisition unit of the mobile evaluation unit is therefore used to analyze ambient light that passes through the gas-sensitive element of the detection unit, and thereby detects a variation of the optical property of the gas-sensitive material and therefore the presence of the target gas.
The detection unit according to the invention comprises at least one optical lens, and the gas-sensitive element and the optical lens are arranged in such a way that ambient light that passes through the gas-sensitive element can be imaged by means of the optical lens. This enables a high-quality analysis of the ambient light that passes through the gas-sensitive element, which is not susceptible to error. The gas-sensitive element and the optical lens are therefore preferably configured in such a way that the ambient light passes through the gas-sensitive element, which is arranged on the mobile evaluation unit, and the information can be imaged onto the image acquisition unit by means of the optical lens.
The optical lens is preferably configured as a converging lens.
The detection unit according to the invention therefore enables economical detection of a target gas since already available mobile devices, for example a cellphone or a tablet computer, are employed as the mobile evaluation unit, and therefore only the detection unit, which preferably does not have any electrical or electronic components, is additionally necessary. Such a detection unit can be produced much more economically compared with previously known gas sensors, so that in combination with the mobile evaluation unit comprising an image acquisition unit, economical detection of a target gas is enabled for private users as well.
The object mentioned in the introduction is therefore likewise achieved by a gas sensor having one or more of the features disclosed herein. The gas sensor has a detection unit according to the invention, in particular an advantageous configuration thereof, and a mobile evaluation unit comprising an image acquisition unit, the mobile acquisition unit being configured as a cellphone or tablet computer.
The image acquisition unit is configured for position-resolved image acquisition, preferably by means of an image acquisition element that is known per se, in particular by means of at least one CCD chip.
The mobile evaluation unit has a computer unit and a memory unit (data memory unit) in order to run programs. In particular, the mobile evaluation unit is configured to run programs in order to evaluate image data that are acquired by means of the image acquisition unit.
This enables the above-described economical gas detection.
The object mentioned in the introduction is likewise achieved by a method having one or more of the features disclosed herein. The method has the following method steps:
This provides an economical method for detecting a target gas, which is straightforward for the user.
In one advantageous embodiment of the detection unit, the detection unit comprises a plurality of optical lenses that are arranged in a lens matrix in order to image a two-dimensional region in a plurality of focusing beams, in particular to image a plurality of focusing beams onto a plurality of differently positioned points of the image acquisition unit when the detection unit is arranged on the mobile evaluation unit.
This provides the advantage that a relatively large area can be imaged onto different detection regions of the image acquisition unit.
The detection unit is preferably arranged removably on the mobile evaluation unit by the user, preferably directly on the image acquisition unit. Typically, it is in this case not possible to establish reliably at which position, in particular in which detection region of the image acquisition unit, the gas-sensitive element of the detection unit is arranged. In one advantageous configuration, the detection unit therefore comprises at least one position mark in order to determine the position of the detection unit relative to the image acquisition unit when the detection unit is arranged on the mobile evaluation unit. The position of the gas-sensitive element relative to the image acquisition unit may thereby be determined straightforwardly, and therefore so can the pixels of the image acquisition unit onto which the ambient light that passes through the gas-sensitive element is focused by means of the optical lens or the plurality of optical lenses in order to image the gas-sensitive element onto the image acquisition unit.
In one advantageous configuration, the position mark is configured as a geometrical shape. The position of the gas-sensitive element may thereby be determined.
Advantageously, the position of the gas-sensitive element, particularly preferably of all gas-sensitive elements if the detection unit has several gas-sensitive elements, is specified, particularly preferably stored in the above-described data memory unit of the mobile evaluation unit. By means of the image acquisition unit, the position mark is acquired and the position of the gas-sensitive element, particularly preferably of all gas-sensitive elements if the detection unit has several gas-sensitive elements, is thereby determined. Preferably, the location and orientation (rotation) of the detection unit relative to the mobile evaluation unit is determined.
It is therefore advantageous that the position mark is configured as a geometrical figure with a rotational symmetry of less than or equal to 2, preferably without a rotational symmetry, in order to reduce, in particular prevent, any ambiguity in the determination of the location.
In one advantageous configuration, the position mark is arranged at a distance from the gas-sensitive element, in particular as a figure and/or pattern that is opaque, in particular configured to be absorbent or reflective, at least for light in the visible wavelength range, preferably in the wavelength range of from 380 nm to 780 nm.
In an alternative advantageous configuration, the position mark is integrated in the gas-sensitive element, and is particularly preferably formed from the gas-sensitive material of the gas-sensitive element.
In a further advantageous configuration, the gas-sensitive element is enclosed at least partially, preferably circumferentially, by an optically transparent region, preferably a region that is transparent in the visible wavelength range, particularly in the wavelength range of from 380 nm to 780 nm. In this advantageous configuration, the position and location, in particular rotation, of the gas-sensitive element relative to the image acquisition unit can therefore be determined by detecting the gas-sensitive element, in particular the edge or the edges of the gas-sensitive element. The transparent regions are preferably also used as a reference region for measuring an intensity variation of the ambient light and/or for a white balance, as respectively described elsewhere.
Advantageously, the gas-sensitive element is therefore configured as a position mark, particularly preferably configured with a shape that has a rotational symmetry of less than or equal to 2, preferably without a rotational symmetry, in order to reduce, in particular prevent, any ambiguity in the determination of the location.
For the detection of different target gases, it is advantageous to provide detection units comprising different gas-sensitive materials, which are suitable for detecting different target gases.
Typically, gas-sensitive materials for different target gases also have a different variation of the optical property upon contact with the target gas.
It is therefore advantageous to establish the evaluation of the data acquired by means of the image acquisition unit specifically for the gas-sensitive material respectively used.
In one advantageous configuration, the detection unit therefore comprises at least one identification mark in order to identify the detection unit by means of the image acquisition unit the detection unit arranged on the mobile evaluation unit.
By the identification of the detection unit, and correspondingly the knowledge thereby obtained about the gas-sensitive material of the detection unit arranged on the mobile evaluation unit, the evaluation of the data, which is specifically adapted for this gas-sensitive material, may take place by means of the image acquisition unit of the mobile evaluation unit.
In one advantageous development of the method according to the invention, a detection unit comprising an identification mark is therefore used. Furthermore, the detection unit is identified by means of the image acquisition unit and identification mark, and, as a function of the identification, one of several evaluation methods stored in the mobile evaluation unit is used for the analysis of the ambient light that passes through the gas-sensitive light.
Typical gas-sensitive materials already differ in their optical properties, in particular their color, in the initial state in the absence of contact with the target gas. In one economical alternative advantageous configuration, the identification of the detection unit takes place via an analysis of the ambient light that passes through the gas-sensitive element by means of the image acquisition unit. With the aid of characteristic data, in particular with the aid of specific spectral data for the different gas-sensitive materials, identification of the detection unit may thus take place without an identification mark being necessary.
In one advantageous configuration, the gas-sensitive element is configured as an identification mark. For this purpose, the gas-sensitive element has a specific shape, which is detected by means of the image acquisition unit in order to identify the detection unit. In particular, several detection units comprising gas-sensitive elements for different target gases may differ from one another in that, in one advantageous configuration, the gas-sensitive elements have different shapes.
The identification mark is preferably configured as a character code, particularly preferably as an optoelectronically readable script, preferably as a barcode or two-dimensional code (matrix barcode), in particular a QR code or data matrix code.
Because of the use of ambient light as the light source, there are typically measurement conditions with a different luminous intensity and different spectra of the light that passes through the detection unit.
In one advantageous configuration, the detection unit therefore comprises at least one reference region that is not gas-sensitive for the target gas and is arranged in such a way that the ambient light that passes through the reference region can be imaged by means of the optical lens or a further optical lens of the detection unit, in particular so that the detection unit arranged on the mobile evaluation unit can be imaged onto the image acquisition unit.
This offers the advantage that the ambient light passing through the reference region can be acquired separately by means of the image acquisition unit, and the intensity and/or the spectrum of the ambient light can be deduced by evaluating these image data and these data are used in the evaluation of the image data that are associated with the ambient light that passes through the gas-sensitive element.
In this case, it is particularly advantageous that the optical properties of the reference region correspond substantially to the optical properties of the gas-sensitive element in the absence of contact with the target gas. In this way, a comparison of the data of the ambient light that passes through the reference region, which are ascertained by means of the image acquisition unit, with the ambient light that passes through the gas-sensitive element is straightforwardly possible, and a deviation that indicates a variation of the optical properties of the gas-sensitive element and therefore a presence of the target gas can be straightforwardly detected.
In one advantageous development of the method according to the invention, a detection unit comprising a reference region that is not gas-sensitive for the target gas is therefore used, and ambient light that passes through the reference region is analyzed by means of the image acquisition unit.
In an alternative advantageous configuration, the reference region is configured to be optically transparent, preferably configured to be transparent in the visible wavelength range, particularly in the wavelength range of from 380 nm to 780 nm. In this configuration, an intensity variation of the ambient light that passes through the reference region is also acquired and taken into account in the evaluation as before. Preferably, the intensity of the ambient light that passes through the reference region and is acquired by means of the image acquisition unit, is therefore additionally acquired and a ratio is formed, in the present case as the quotient of this reference intensity to the light intensity of the ambient light that passes through the gas-sensitive element. Erroneous detections in the event of a varying intensity of the ambient light may be avoided by taking this reference intensity into account.
In one advantageous development, the ambient light that passes through the reference region is additionally used for a white balance, as described further below.
In order to increase the accuracy when acquiring a color variation of the gas-sensitive element by means of the image acquisition unit, it is advantageous to carry out a color calibration, preferably before method step B. Advantageously, the detection unit therefore has a calibration scale that comprises several colored areas, particularly preferably a calibrated color pattern, preferably an RGB or CMYK color scale. The ambient light that passes through the calibration scale is acquired by means of the image acquisition unit. The calibration data, in particular the color data of the calibration scale, are furthermore predefined, in particular stored in a memory unit of the mobile evaluation unit. A color calibration of the image acquisition unit is carried out by means of these data, preferably before carrying out the gas detection.
Advantageously, the detection unit comprises a flexible film as the carrier substrate and the gas-sensitive element and the optical lens are formed in the carrier substrate and/or arranged on the carrier substrate. This enables simple handling of the detection unit.
It is within the scope of the invention that the gas-sensitive material of the gas-sensitive element is arranged on the carrier substrate, preferably on the front side of the carrier substrate that faces away from the detection unit of the evaluation unit, which is arranged on the mobile evaluation unit.
It is within the scope of the invention that the optical lens is arranged on an opposite side of the carrier substrate from the gas-sensitive element.
In one advantageous configuration, the optical lens and the gas-sensitive element are arranged on a common side of the carrier substrate. In particular, it is advantageous that the optical lens is arranged between the gas-sensitive element and the carrier substrate. In this way, direct contact between the optical lens and the mobile evaluation unit is not necessary.
It is likewise within the scope of the invention that the gas-sensitive element is formed in the carrier substrate by the gas-sensitive material being embedded into the carrier substrate. This provides a robust structure.
In a further advantageous configuration, the optical lens is formed in the carrier substrate. It is within the scope of the invention that the optical lens is formed in the carrier substrate by modifying the refractive index. It is likewise within the scope of the invention that the optical lens is formed by embossing or stamping.
In one advantageous configuration, the optical lens is configured as a Fresnel lens. This enables economical production and a small overall thickness of the detection unit.
Advantageously, the carrier substrate comprises an adhesive layer in order to arrange the detection unit removably on the mobile evaluation unit. This ensures simple handling for the user. For residue-free removable arrangement of the carrier substrate on the mobile evaluation unit, an adhesive based on rubber or acrylate is preferably used as the adhesive.
It is within the scope of the invention that the detection unit has precisely one gas-sensitive element comprising precisely one gas-sensitive material. In this way, the detection of a target gas may take place economically.
It is within the scope of the invention that the detection unit has a plurality of gas-sensitive elements lying next to one another. In one advantageous configuration, these gas-sensitive elements comprise the same gas-sensitive material. In this way, redundant measurements may be carried out in order to increase the accuracy of the measurement.
In a further advantageous configuration, the detection unit has a plurality of gas-sensitive elements lying next to one another and comprising different gas-sensitive materials, so that several target gases can be detected without the detection unit having to be replaced.
The present invention furthermore enables the economical provision of a system which is suitable for detecting different target gases:
The system according to the invention for detecting a plurality of different target gases has a plurality of detection units according to the invention, in particular according to an advantageous configuration, each detection unit being configured to detect a different target gas than the other detection units and comprising a different identification mark and/or a different reference region than the other detection units.
The system furthermore has a mobile evaluation unit comprising an image acquisition unit, in particular a cellphone or a tablet computer, the mobile evaluation unit being configured to identify the detection unit as a function of the optical data of the identification mark and/or of the reference region of the detection unit that are acquired by means of the image acquisition unit.
The user may thus select the corresponding detection unit according to the desired target gas and arrange it on the mobile evaluation unit. With the aid of the identification mark of the detection unit and/or of the reference region, the mobile evaluation unit automatically identifies the detection unit arranged on the evaluation unit and correspondingly selects the appropriate evaluation of the image data, ascertained by means of the image acquisition unit, of the ambient light that passes through the gas-sensitive element of the detection unit.
Advantageously, a plurality of evaluation methods are therefore stored in a data memory of the mobile evaluation unit and a selection of the evaluation method for detecting a target gas takes place as a function of the identification of the detection unit.
It is in this case within the scope of the invention that the evaluation methods for different target gases differ merely in parameters of the evaluation method that are specific for a respective target gas. It is likewise within the scope of the invention to provide different evaluation methods, having different evaluation steps, for different target gases.
In one advantageous configuration of the method according to the invention, the position of the gas-sensitive element relative to the image acquisition unit is determined in order to localize an analysis region of the image acquired by the image acquisition unit, on which the ambient light that passes through the gas-sensitive element is incident. As described above, this ensures that only the relevant regions, in particular the relevant pixels, of the image acquisition unit on which the ambient light passing through the gas-sensitive element is incident are used for the detection of the target gas.
Advantageously, the position of the gas-sensitive element is determined with the aid of one or more of the following features a circumferential edge of the gas-sensitive element, which has different optical properties than the gas-sensitive element;
In one advantageous configuration of the method according to the invention, a white balance (AWB-automatic white balance) of the image acquisition unit takes place between method steps A and B in order to reduce the risk of erroneous detection. In particular, it is advantageous that the detection unit has at least one reference region that does not comprise a gas-sensitive element, in particular which is configured to be optically transparent at least in the visible wavelength range, preferably in the wavelength range of from 380 nm to 780 nm. The ambient light which is detected by means of the image acquisition unit and passes through the white balance region, is therefore not modified by absorption of a gas-sensitive element and is used to carry out the white balance.
Gasochromic dyes have the capability of varying their color in the visible spectral range during the reaction with a target gas. Ideally, the dye and the gas match like a “key and lock” so that only a particular gas selectively initiates the color variation. The color variation of the gas-sensitive material corresponds directly to the absorption variation of the light that passes through the gas-sensitive material, and is specific for the respective dye. This variation may be detected with the image acquisition unit of the mobile evaluation unit, in particular by means of a camera chip.
Examples of color-sensitive dyes and the detectable target gases are given in Table 1 below.
In order to avoid incorrect measurements, it is advantageous to carry out at least one self-test, in which at least one of the following checks is carried out, before method step B, preferably between method steps A and B:
Such checks make it possible to identify faulty detection units. With the aforementioned check criterion a), for example, it is possible to identify wrong detection units, as well as damaged detection units in which the gas-sensitive element is damaged and therefore has a different shape. With test criterion b), for example, it is possible to identify wrong detection units without or with unknown gas-sensitive material. It is likewise possible to identify if the detection unit used has already come into contact with the target gas and a color change has already taken place.
Preferably, a warning is emitted to the user in the event of the test criterion or criteria not being satisfied, in particular an optical and/or acoustic warning by means of a display unit and/or a loudspeaker unit of the mobile evaluation unit.
The optical lens is preferably configured as a converging lens and preferably has a focal length in the range of from 1 mm to 2 cm.
Further advantageous features and configurations will be explained below with the aid of exemplary embodiments and the figures, in which:
All the figures show schematic representations that are not true to scale. Reference signs that are the same in the figures denote elements that are the same or have the same effect.
The detection unit has a gas-sensitive element 1 comprising a gas-sensitive material. The gas-sensitive element is configured in a manner known per se as a gasochromic layer, so that the optical absorption properties vary as a function of the contact with a target gas. In the present case, the gas-sensitive material of the gas-sensitive element is formed as bromophenol blue in order to detect ammonia (NH3) as the target gas.
Examples of alternative configurations with alternative dyes and the target gases that can be detected with them are given in the aforementioned Table 1.
The detection unit comprises an optical lens 2 configured as a converging lens, which is arranged on an optically transparent lens carrier element 3. The optical lens and the lens carrier element 3 are formed in the present case from polymers.
The gas-sensitive element 3 is arranged on the lens carrier element 3.
The detection unit is configured for removable arrangement on a mobile evaluation unit comprising an image acquisition unit, in order to form a gas sensor.
For this purpose, the detection unit according to the first exemplary embodiment comprises a carrier substrate 4 configured as a flexible film, which is optically transparent and is formed from polymers.
The gas-sensitive element 1 and the optical lens 2 are arranged in such a way that the ambient light that passes through the gas-sensitive element 1 is focused by means of the optical lens 2.
By means of the carrier substrate 4, the detection unit is arranged on the mobile evaluation unit so that the ambient light that passes through the gas-sensitive element 1 can be imaged by means of the optical lens 2 onto the image acquisition unit of the mobile evaluation unit 5, as explained in more detail below in
Because of the low weight of the detection unit, there is already a sufficient grip on the mobile evaluation unit by the air pressure of the surroundings.
In one development of the first exemplary embodiment, the carrier substrate 4 is configured as an adhesion film in order to achieve a better grip.
In an alternative development, the carrier substrate 4 has in the present case an adhesive layer based on rubber on the side facing away from the optical lens 2 in order to arrange the detection unit removably on the mobile evaluation unit. In an alternative configuration, the adhesive layer is one or adhesive layers based on acrylate. The use of other adhesive layers also lies within the scope of the invention.
The image acquisition unit 6 of the mobile evaluation unit 5 comprises a first camera shown at the top in
The edges of the lens carrier element 3 are represented by dashes.
The ambient light passes through both the gas-sensitive element 1 and the region enclosing the gas-sensitive element 1, and is focused by means of the optical lens 2 onto the image acquisition unit 6 of the mobile evaluation unit 5 so that the gas-sensitive element is imaged onto the image acquisition unit 6.
The mobile evaluation unit 5 comprises a computing unit and a data memory unit. An evaluation program is stored in the data memory unit in order to analyze the image data of the image acquisition unit 6 by means of the computer unit.
Even if there is no contact between a target gas and the gas-sensitive element 1, the position of the gas-sensitive element can be ascertained by means of analyzing the position-resolved image data of the image acquisition unit 6, since the gas-sensitive element has an absorption and therefore a characteristic color even in the absence of contact with the target gas and can therefore be localized in the image data of the image acquisition unit 6, for example by filtering over pixels with the corresponding color values.
During the evaluation, a localization of those pixels which acquire ambient light that passes through the gas-sensitive element initially takes place as described above.
Since the gas-sensitive material used and its optical properties are known, a color spectrum that corresponds to the color of the gas-sensitive element upon contact with the target gas is furthermore predefined in the evaluation program.
By means of the evaluation program, whether a color change takes place in the predefined spectrum at the pixels of the image acquisition unit 6 that are assigned to the gas-sensitive element is then repeatedly checked. If there is a color change, a warning message that the target gas has been detected is emitted to the user on a display unit of the mobile evaluation unit 5, which is arranged on the opposite side of the mobile evaluation unit 5 from the image acquisition unit 6.
In an alternative configuration, the light intensity is used by means of the evaluation program and the image acquisition unit 6 only as an indicator in order to detect a variation of the optical properties of the gas-sensitive element and therefore a presence of the target gas. With such an evaluation, the risk exists that a variation of the intensity of the ambient light leads to an erroneous detection. In one development of the exemplary embodiment, the intensity of the ambient light acquired by means of the image acquisition unit 6, which does not pass through the gas-sensitive element, is therefore additionally acquired and a ratio is formed, in the present case as the quotient of this reference intensity to the light intensity of the ambient light that passes through the gas-sensitive element. Erroneous detections in the event of a varying intensity of the ambient light may be avoided by taking this reference intensity into account.
In a variant of the exemplary embodiment represented in
The detection unit according to the second exemplary embodiment has in total nine gas-sensitive elements comprising different gas-sensitive materials, so that 9 different target gases can be detected. The nine gas-sensitive elements are arranged in a square 3×3 matrix on the lens carrier element 3. In the sectional representation according to
In the plan view from above shown in
The rectangular grid formed by the distances between the gas-sensitive elements can therefore be detected by means of the image sensor 6a of the image acquisition unit 6. The position of the detection unit relative to the mobile evaluation unit 5 can be deduced with the aid of the location of the rectangular grid. In particular, whether all 9 fields of the rectangular grid are acquired by means of the image acquisition unit 6 is checked. If this is not the case, an error message is emitted to the user via the optical display of the mobile evaluation unit 5 so that they can position the detection unit correctly.
The third exemplary embodiment shown in
In contrast to the 1st and 2nd exemplary embodiments of a detection unit, the detection unit represented in
The optical lenses 2 comprise an adhesive layer in order to arrange the detection unit on the mobile evaluation unit 5. For illustration,
An essential difference from the first exemplary embodiment represented in
The gas-sensitive element comprises a plurality of angular elements. The position of the angle elements is acquired by means of the image sensor so that the position and rotation of the gas-sensitive element relative to the image sensor can be acquired. Furthermore, the detection unit can be distinguished from other detection units that comprise a gas-sensitive element, the shape and/or individual elements of which are configured differently than that shown in
The detection unit is identified with the aid of the shape of the gas-sensitive element, so that the evaluation takes place specifically for the gas-sensitive element applied on the mobile evaluation unit, and the target gas detected by this gas-sensitive detection unit can be displayed in plain text to the user on an optical display of the mobile evaluation unit 5.
The gaps between the angular elements of the gas-sensitive element are optically transparent for light in the visible range, so that the intensity of the ambient light can be measured by means of the pixels of the image sensor of the image acquisition unit 6 which acquire ambient light that passes through these gaps, and a fluctuation in the intensity of the ambient light can be taken into account as described above by forming the quotient during the evaluation.
This application mis a 371 National Phase of International Application No. PCT/EP2022/086825, filed Dec. 20, 2021, which is incorporated herein by reference as if fully set forth.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/086825 | 12/20/2021 | WO |
