KR20200103092A - Optical sensor module for spectroscopic measurement - Google Patents

Abstract

The present invention relates to an optical sensor module for analyzing a fluid or object, such an optical sensor module, one or more for generating an electromagnetic beam in a wavelength range and emitting an electromagnetic beam in the direction of the fluid or object to be tested A light source; One or more detectors for receiving the reflected beam on the fluid and converting the received beam into electronic measurement signals; At least one base portion for positioning and aligning at least one light source and at least one detector on the circuit board; And one or more signal processing units for amplifying and processing the electronic measurement signals of one or more detectors, wherein the one or more light sources can be positioned parallel or inclined with respect to one or more detectors through one or more base portions on a circuit board.

Description

Optical sensor module for spectroscopic measurement

The invention relates to an optical sensor module for analyzing fluids or objects, according to the preamble of claim 1.

Optical sensor modules are already used in a number of applications. For example, non-dispersive infrared (NDIR) detectors can determine the CO ₂ content in the ambient air, or the moisture content in gases or other materials. In particular, sensors of this type can be used to detect and spectrally evaluate certain material properties and mixing ratios of media such as gas, solid or liquid, for example. One of the possible applications for a miniaturized optical sensor is the monitoring of cleaning or drying process parameters.

Sensors can perform reflection measurements, for example. In such a measurement method, the detector and the emitter are typically located on the same side of the measurement section, and the IR beam generated by the emitters is guided through the optical path, and this optical path can change over time, which is for example For example, this is because the spacing of the sensor to the measurement sample changes.

The basis for spectral evaluation of an optical sensor is a uniform spectral response, which can be made up of multiple wavelengths. When the sensor is formed in one plane, for example one circuit board, there are challenges, such as optimal beam focusing, for example to obtain a uniform spectral response.

There are also numerous applications where the distance between the object and the sensor module changes during measurement, especially in reflection measurement. Since even small deviations in the emitter and detector arrangement and the emitter's emission characteristics negatively affect the sensor's spacing dependence, the sensor's operating range can be severely limited for highly precise measurement tasks.

It is an object of the present invention to provide an optical sensor module having improved spectral uniformity, which can be manufactured technically simply.

This task is solved by the subject of each of the independent claims. Preferred embodiments of the invention are the subject of their respective dependent claims.

According to an aspect of the present invention, an optical sensor module for analyzing a fluid or object is provided. Such sensor modules have one or more light sources for generating an electromagnetic beam in one wavelength range and emitting the electromagnetic beam in the direction of the fluid or object to be tested. In addition, the sensor module has one or more detectors for receiving a beam reflected on a fluid or object and converting the received beam into electronic measurement signals. The sensor module has one or more bases for positioning and aligning one or more light sources and one or more detectors on a circuit board. One or more signal processing units of the sensor module are used to amplify and process electronic measurement signals of one or more detectors. In accordance with the present invention, one or more light sources can be positioned parallel or obliquely relative to one or more detectors through one or more bases on a circuit board.

In this case, the one or more light sources may be, for example, one or more infrared LEDs or infrared lasers.

In order to be able to implement the optical sensor concept as cost-effectively as possible, it is desirable to miniaturize the light source and simply configure the light path by the appropriate selection of design parameters, material parameters and optical components. In general, in order to realize miniaturization, a so-called through-hole component or an SMD mountable component for insert mounting is used. From this, all necessary components must be arranged as far as possible in one plane, for example on one circuit board or in one TO-cell. Through this structure, it is possible to perform the mounting of the elements very quickly and inexpensively.

Through the base, a mechanical structure that can be arranged on a circuit board for receiving at least one detector and at least one light source can be implemented. Accordingly, simple and inexpensive beam guidance or beam focusing through appropriate positioning of the optical components relative to each other can be implemented. In addition to the precise alignment of the optical components of the sensor module, the sensor module can be technically simply mounted or manufactured. Further, the light sources may be positioned or aligned relative to one or more detectors through the base in such a way that scattered light is reduced or prevented.

According to an embodiment of the optical sensor module, one detector can be positioned at the center between two or more light sources within one or more bases. By opposing arrangement of two or more light sources having the same wavelength range, the spectral uniformity of the sensor module can be optimized. In particular, this can compensate for variations in the wavelength ranges of the light sources. This leads to an improved distribution of spectral components of the generated beams within the measurement volume in which the sample or object is positioned, and can achieve a more uniform spectral distribution.

According to a further embodiment of the optical sensor module, one light source can be positioned at the center between two or more detectors within one or more bases. As an alternative to the detector arrangement between a plurality of light sources, a broadband light source or emitter may be used in combination with a plurality of detectors for detecting a specific spectral range. Due to this, variations in the emission characteristics of the light source can be compensated for by a detectable larger wavelength range of a plurality of detectors that are the same or different.

According to a further embodiment of the optical sensor module, at least one base portion has a shape of rotational symmetry, and at least one base portion has at least one socket for receiving the detector and at least one socket for receiving the light source. Through the receptacles or sockets provided in the base, the optical components can be inserted formally into the base. In particular, one or more light sources and one or more detectors can be optimally aligned optically in a state inserted into the receptacles.

According to a further embodiment of the optical sensor module, the one or more base portions shield the one or more detectors arranged in the socket from electromagnetic beams at least by region. Due to this, undesirable crosstalk of light sources to one or more detectors or scattered light in the housing can be reduced or prevented. Thus, the usable dynamic range of the sensor can be expanded. Alternatively or additionally, the base can advantageously act on multiple reflections on the corresponding reflective surfaces, in the receiving area of one or more detectors, thereby improving the performance of the sensor module.

According to a further embodiment of the optical sensor module, the optical sensor module has one or more spacing sensors for detecting spacing of one or more detectors with respect to an object.

With an additional sensor, a gap measurement can be performed that can be used to compensate for the existing gap dependency of the sensor module. Accordingly, the operating range of the sensor module can be expanded.

According to a further embodiment of the optical sensor module, the at least one signal processing unit has an offset tracking portion of the electrical measurement signals and/or a variable amplification portion of the electrical measurement signals. Due to this, since one or more signal processing units may have a signal conditioning unit and a signal processing unit, the sensor module can be adapted to application-specific requirements.

According to a further embodiment of the optical sensor module, the optical sensor module has a temperature sensor for performing temperature compensation. Due to this, in the evaluation of the measurement signals of one or more detectors by the one or more signal processing units, the thermal effect on the beam properties of the emitter or one or more detectors and on the materials to be tested can be taken into account. In particular, through the additional temperature information, influences due to temperature in the range of processing of the measurement signals can be compensated.

According to a further embodiment of the optical sensor module, one or more light sources, one or more detectors, one or more bases, one or more signal processing units and one or more energy supply units are arranged in a closeable housing to be fluidly sealed. Preferably, the housing can be closed by a cover and can be sealed against environmental influences, for example by sealing means such as O-rings. The housing may be made of plastic, or may be made of metal impregnated or varnished to be waterproof. Thus, the sensor module can be used even in a humid environment, and the components of the sensor module are arranged to be protected within the housing.

According to a further embodiment of the optical sensor module, the housing has one or more windows for transmitting electromagnetic beams of one or more light sources. Thus, an electromagnetic beam generated by one or more light sources can be emitted from the housing. In this case, in particular the optical components of the sensor module can be arranged to be protected in the housing.

According to a further embodiment of the optical sensor module, the one or more detectors are positionable to directly contact one or more windows through one or more bases arranged within the housing. One or more detectors may be positioned within the housing through one or more bases such that the detector is arranged in direct contact with the window of the housing. In particular, since the detector can be positioned orthogonal to the flat extension of the window, reflection can be reduced. Depending on the configuration of the at least one base, the receiving portion of the detector can shield the detector against the window on the circumferential side, thereby protecting the detector from scattered light from the housing.

The detector according to the invention is particularly suitable for use in washing machines or dishwashers.

In the following, preferred embodiments of the invention are described in more detail on the basis of very simplified schematic drawings. in this case,
1A is an exploded perspective view illustrating a base portion having a plurality of light sources and a detector of a sensor module according to a first embodiment of the present invention.
1B is an exploded perspective view illustrating a base portion having a plurality of light sources and one detector of a sensor module according to a second embodiment of the present invention.
2 is a diagram schematically illustrating irradiation through a sensor module according to a second embodiment.
3A is an exploded perspective view showing a sensor module according to a first embodiment of the present invention.
3B is an exploded perspective view showing a sensor module according to a second embodiment of the present invention.
4 is a circuit diagram schematically showing a signal processing unit of a sensor module according to an embodiment of the present invention.
5 is a diagram schematically showing a sensor module according to a third embodiment of the present invention.

In the drawings, the same structural elements each have the same reference numerals.

1A shows an exploded perspective view of a base 1 with a plurality of light sources 2 and a detector 4 of a sensor module 6, according to a first embodiment of the present invention.

The base 1 has a shape of rotational symmetry and has six receiving portions 8 each for receiving one light source 2. Receptacles 8 for receiving light sources 2 are arranged around one receptacle 10 for receiving one detector 4. Further, the receiving portions 10 for receiving the detector 4 are arranged displaced relative to the receiving portions 8 of the light source 2 in the emission direction of the light sources 2.

According to the first embodiment of the sensor module 6, the light sources 2 and the detector 4 are arranged parallel to each other in the base 1 or in the receiving parts 8, 10 of the base 1 Position can be set.

In this case, the light sources 2 are for example infrared LEDs with a diameter of 3 mm or 5 mm. The light sources 2 can emit an electromagnetic beam within a wavelength range of 800 nm to 1000 nm.

Since the base 1 is formed flat at an end opposite to the receiving part 10 of the detector 4, the base 1 can be arranged in a form-coupled manner on a flat circuit board. The base 1 has passage bores for the contacts of the light sources 2 and the detector 4, which are guided through the base 1 in a direction opposite to the beam direction of the light sources 2. Accordingly, the contact portions guided through the base portion 1 are aligned toward each other, so that they can be optimally positioned on the circuit board.

1B shows an exploded perspective view of a base portion 1 having a plurality of light sources 2 and one detector 4 of a sensor module 6, according to a second embodiment of the present invention. Unlike the first embodiment of the sensor module 6, the light sources 2 in this embodiment are arranged at an angle relative to the detector 4. In particular, the light sources 2 are arranged to be inclined or inclined toward the axis of rotation of the base portion 1 which is rotationally symmetric. This can be achieved by means of the receiving portions 8 of the light sources 2 formed to be inclined correspondingly. Due to this, an overlapping area of the electromagnetic beams generated by the light sources 2 can be formed, and this overlapping area forms a uniform emission area of the light sources 2 and makes the manufacturing tolerance of the light sources 2 You can compensate.

Fig. 2 schematically shows irradiation through the sensor module 6 according to the second embodiment. In particular, a cross section of the base 1 is shown. In this case, the inclined arrangement of the light sources 2 with respect to the detector 4 and the direction of travel of the contact portions of the detector 4 and the light sources 2 are shown.

As the detector 4 is arranged displaced relative to the light sources 2 within the base 1, the detector 4 can be positioned so as to directly contact the window 12 of the sensor module 6. In this case, the detector 4 is arranged in the base portion 1 so that a wall portion 11 surrounding the receiving portion 10 of the detector 4 can protect and shield the detector 4 from control light. Preferably, the base portion 1 positions the sensor module 6 on the window 12 such that there is no or minimum clearance between the wall portion 11 and the window 12.

The electromagnetic beam generated by the light sources 2 is emitted from the sensor module 6 through the window 12. By means of a plurality of light sources 2, an overlapping area A is generated which is constituted as the sum of electromagnetic beams generated from all light sources 2. Due to this, the manufacturing tolerance of the light sources 2 can be compensated.

Optionally, it is possible to configure the base 1 to be movable so that one or more individual light sources 2 and/or detector 4 can be aligned. For this, an actuator assigned to the light source 2 or the detector may be provided. Further, optionally, the base portion 1 may be configured in a multi-member type, and one member of the base portion 1 can be moved relative to the other member. Due to this multi-member configuration, the light source 2 or the detector 4 can each be aligned towards a different element. In one particular embodiment, each member of the multi-membered configuration of the base 1 is provided with its own actuator, so that each member can be controlled and positioned independently of each other. Control of one or more actuators can be carried out via the signal processing unit 26, for example in accordance with the measurement signals of the detector 6.

3A and 3B are exploded perspective views of sensor modules 6 according to the first and second embodiments of the present invention. The sensor module 6 has a housing 14 that can be closed with a cover 18 so as to be fluidly sealed by a sealing ring 16. The cover 18 has an external blocking portion for installing the window 12. Through the window 12, the generated electromagnetic beams can be emitted from the housing 14 of the sensor module 6. In this case, the window 12 can be positioned on the cover 18 using a sealing ring 16. For example, window 12 may be glued within a recess of cover 18.

Further, the sensor module 6 has a first circuit board 20. On the first circuit board 20, the base 1 is fixed via screw connections 22. In this case, the light sources 2 and the detector 4 can be electrically conductively clamped or soldered with the circuit board 20.

Further, the sensor module 6 has a first circuit board 20 and a second circuit board 24 electrically conductively connected. On the second circuit board 20, for example, a power supply of the sensor module 6; One or more signal processing units 26 for evaluating the electrical signals of the detector 4 are arranged. The power supply may be formed through, for example, a battery or an external current connection.

Each of the components 18, 1, 24 can be securely fixed to each other and/or to the housing 14 via threaded connections 28.

4 schematically shows a circuit diagram of the signal processing unit 26 of the sensor module 6 according to an embodiment of the present invention. In particular, an exemplary circuit of the signal path of electrical measurement signals generated by the detector 4 in this case is shown.

The detector 4 is shown with a transimpedance amplifier 30 connected downstream. In this case, the transimpedance amplifier 30 may be arranged on the first circuit board 20, for example, and the amplified measurement signals of the detector 4 are controlled through corresponding data lines not provided with reference numerals. 2 can be transferred to the circuit board 24.

On the second circuit board 24, for example, a differential amplifier 32 may be provided. By means of the differential amplifier 32, offset corrections of different measurement signals of different light sources 2 through the digital-to-analog converter 34 of the signal processing unit 26 can be performed. Due to this, the measurement signals can be converted into a linear region of subsequent circuit elements.

In this case, the second operational amplifier 36 is arranged on the second circuit board 24. The second operational amplifier 36 enables variable amplification of signals processed by the signal processing unit 26. Particularly preferred is the use of a variable amplification section in different detection regions and an offset tracking section of the differential amplifier 32, for example in a very weak moisture dependent signal. Within the detection area, the measurement signal can be more accurately tracked by the digital-to-analog converter 34, and the amplification can be switched to a higher level.

5 schematically shows a sensor module 6 according to a third embodiment of the present invention. Unlike the embodiments of the present invention described above, the sensor module 6 has a temperature sensor 38 and an interval sensor 40. Through the temperature sensor 38, temperature dependent deviations in the emission characteristics of the object 42, the light sources 2, the detector 4 or the fluid to be tested are further evaluated by the signal processing unit 26. Can be considered in

In this case, the gap sensor 40 may be an optical sensor or an ultrasonic sensor. Through the distance sensor 40, the distance dependency of the measurement signals reflected from the object 42 may be compensated.

Due to the tolerances to the system and component plane, misadjustment of the optical elements with respect to each other can occur. This misadjustment can be problematic in spectroscopy applications, typically where one or more wavelengths of the measurement channel are compared to the wavelength of a reference channel. This misadjustment results in a sensor-specific spacing dependency, which can be compensated for through the use of the spacing sensor 40.

In particular, when measuring through the sensor module 6 in the reflection mode, the distance between the sensors 4 and 6 with respect to the object 42 may change, so the distance sensor 40 for measuring the distance is used as the sensor module 6 By incorporating into, the possibility of compensating for the spacing dependence of the measurement signals is achieved.

In addition, Fig. 5 shows an overview of all relevant components of the sensor module 6 according to the third embodiment of the present invention.

A further embodiment relates to a method for evaluating the electronic measurement signals received by the detector 4, which method can be implemented, for example, in the signal processing unit 26. In this case, the measurement signals are processed so that the signal processing unit 26 represents one or more signals depending on the intensity of the beam returning from the one or more light sources 2 onto the detector 4. It is also conceivable that the signals of the signal processing unit 26 are generated according to the measurement parameters of the temperature sensor 38 and/or the interval sensor 40.

Claims (13)

It is an optical sensor module 6 for analyzing the fluid or object 42,
-At least one light source 2 for generating an electromagnetic beam of one wavelength range and emitting an electromagnetic beam in the direction of the fluid or object 42 to be tested,
-One or more detectors 4 for receiving the beam reflected on the fluid or object 42 and converting the received beam into electronic measurement signals,
-At least one base 1 for positioning and aligning at least one light source 2 and at least one detector 4 on the circuit board 20,
-In the optical sensor module, comprising at least one signal processing unit (26) for amplifying and processing the electronic measurement signals of at least one detector (4),
An optical sensor module, characterized in that at least one light source (2) can be positioned parallel or inclined with respect to at least one detector (4) via at least one base (1) on a circuit board (20). The optical sensor module according to claim 1, wherein one detector (4) is centerable between two or more light sources (2) within at least one base (1). The optical sensor module according to claim 1, wherein one light source (2) is centerable between two or more detectors (4) within one or more bases (1). The method according to any of the preceding claims, wherein at least one base (1) has a shape of rotational symmetry, and at least one base (1) comprises at least one socket (10) for receiving the detector (4) and Optical sensor module, having at least one socket (8) for receiving a light source (2). 5. Optical sensor module according to any of the preceding claims, wherein at least one base (1) shields at least one detector (4) arranged in the socket (10) from electromagnetic beams at least area by region. The method according to any of the preceding claims, wherein the optical sensor module (6) has at least one distance sensor (40) for detecting the distance of at least one detector (4) with respect to the object (42). Optical sensor module. 7. Optical according to any of the preceding claims, wherein at least one signal processing unit (26) has an offset tracking section (32) of electrical measurement signals and/or a variable amplification section (36) of electrical measurement signals. Sensor module. 8. Optical sensor module according to any of the preceding claims, wherein the optical sensor module (6) has a temperature sensor (38) for performing temperature compensation. The method according to any one of the preceding claims, wherein at least one light source (2), at least one detector (4), at least one base (1), at least one signal processing unit (26) and at least one energy supply unit are , An optical sensor module arranged in a closureable housing (14, 18) to be fluidly sealed. 10. Optical sensor module according to any of the preceding claims, wherein the housing (14, 18) has at least one window (12) for transmitting the electromagnetic beam of at least one light source (2). 10. Optical sensor module according to claim 9, wherein the at least one detector (4) is positionable in direct contact with at least one window (12) through at least one base (1) arranged in the housing (14, 18). A method for evaluating the sensor signal of the sensor module according to any one of claims 1 to 11, generated by one or more light sources (2) and emitted in the direction of the fluid or object to be tested (42), A method for evaluating a sensor signal of a sensor module, wherein the detector signal of the detector 4 is amplified and processed according to the electromagnetic beam reflected by the detector 4. 13. The method according to claim 12, wherein the sensor signal is varied according to the measurement parameters of the temperature sensor (38) and/or the interval sensor (40).

Images