Device and coating installation for determining optical properties of optically transparent substrate

Abstract

A device (24) for determining optical properties of an optically transparent substrate (14) provided with a substrate coating (12) on a first side (36) has a first operating mode and a second operating mode, in which a first emission unit (40) is active and a second emission unit (58) is inactive, and in which a second emission unit (58) is inactive. The first emission unit (40) is inactive and the second emission unit (58) is active such that, in an operating mode, reflected and transmitted electromagnetic radiation can be detected by means of the first detector unit (50) or the second detector unit (60). The invention further relates to a coating system (10).

Description

Technical Field

[0001] The invention relates to a device for determining optical properties of an optically transparent substrate and a coating system for producing an optically transparent substrate. Background Art

[0002] In the production of optically transparent substrates, such as those used in architectural glazing and solar modules, coatings are often applied to the substrates in order to achieve the desired property profile of the coated substrate, for example, with respect to transmission properties or thermal insulation. In this context, it is crucial to be able to reliably determine the quality of the coated substrates and the optical properties actually achieved.

[0003] In this context, devices are known in which coated substrates are inspected using a measuring unit configured to emit electromagnetic radiation toward the substrate. For this purpose, the measuring unit comprises a transmitting unit oriented perpendicularly to the surface of the substrate so that the substrate can be irradiated with electromagnetic radiation, which thus impinges perpendicularly on the substrate. A detector unit associated with the transmitting unit can measure the transmission and reflection of the electromagnetic radiation and draw conclusions about the quality of the coated substrate.

[0004] A particular disadvantage of known solutions is that they cannot simultaneously measure transmission and reflection at the coated substrate. This prolongs the necessary measurement time and is particularly disadvantageous in coating systems where the substrate moves in the process direction, requiring measurements to be performed on the moving substrate. The temporally offset measurements and the moving substrate result in a relatively large measurement area to be examined, making precise determination of substrate properties difficult. Summary of the Invention

[0005] The object of the present invention is to provide a device with which the optical properties of an optically transparent substrate can be determined reliably and precisely.

[0006] According to the present invention, the object is achieved by an apparatus for determining optical properties of an optically transparent substrate, the substrate being provided with a substrate coating on one side. The apparatus comprises a first measuring unit and a second measuring unit, wherein the first measuring unit is associated with a first side of the substrate and the second measuring unit is associated with a second side of the substrate, opposite the first side. The first measuring unit comprises a first transmitting unit for irradiating a measurement region of the substrate with directed electromagnetic radiation and a first detector unit. The second measuring unit comprises at least one second transmitting unit for irradiating the measurement region of the substrate with directed electromagnetic radiation and at least one second detector unit. The apparatus has a first operating mode and a second operating mode, wherein in the first operating mode, the first transmitting unit is active and the second transmitting unit is inactive, and in the second operating mode, the first transmitting unit is inactive and the second transmitting unit is active, such that in the first operating mode, electromagnetic radiation reflected by the substrate coating in the measurement region can be detected in the first detector unit, and electromagnetic radiation transmitted by the substrate in the measurement region can be detected in the second detector unit, and in the second operating mode, electromagnetic radiation transmitted by the substrate in the measurement region can be detected in the second detector unit.

[0007] The present invention is based on the basic idea of ​​using the same measurement area to determine different parameters of a coated, optically transparent substrate, which parameters allow conclusions to be drawn about the quality of the substrate, including the substrate coating applied thereto. The device according to the present invention is designed so that, in a first operating mode, reflection caused by the substrate coating, i.e., reflection associated with a first side of the substrate, and transmission through the substrate can be measured at the same time. In other words, after impinging on the coated substrate, the electromagnetic radiation emitted by the first transmitting unit interacts not only with the first detector unit associated with the first side of the substrate, but also with the second detector unit associated with the second side of the substrate. This method reduces the measurement duration and minimizes the size of the measurement area, regardless of whether the substrate remains stationary or moves during the measurement.

[0008] At the same time, different transmitting units are provided which can be used to determine different optical properties of the coated substrate in the same measurement region, wherein the respective measuring conditions are influenced by the coating applied to the first and / or second side of the substrate.

[0009] It goes without saying that the substrate coating on the first side can also only partially cover the first side. Furthermore, the second side can also be provided with a substrate coating, wherein the substrate coatings associated with the first and second sides can be identical or different. The substrate coating can also include one or more coatings. The only crucial factor is that the coating applied to the optically transparent substrate results in a coated substrate that is still optically transparent.

[0010] According to the present invention, the first and second transmitting units emit directed electromagnetic radiation. The term "directed electromagnetic radiation" in this context means that the electromagnetic radiation has no scattered light contribution, apart from the unavoidable scattered light contribution from the surroundings of the measurement region. This minimizes possible sources of error in the measurement data obtained with the aid of the detector unit, thereby optimizing the quality of the determination of the optical properties of the substrate.

[0011] In other words, the directed electromagnetic radiation is not diffuse light, so that the first emitting unit and the second emitting unit are not diffuse emitting units.

[0012] The first and / or second transmitting unit can be arranged relative to the first or second side of the substrate such that the emitted electromagnetic radiation has a first or second emission angle relative to the normal to the first or second side of the substrate in the range of 3° to 10°, for example, a first or second emission angle of 8°. In other words, in this embodiment, an angular offset of the corresponding transmitting unit relative to the surface of the coated substrate is selected that enables simultaneous measurement of reflection and transmission and also ensures that both measurements are performed in the same measurement area.

[0013] The angular tolerance of the first emission angle or the second emission angle can be defined by a tolerance range that is determined according to the substrate thickness and the substrate's refractive index. For example, with a substrate thickness of up to 30 mm and a substrate refractive index of up to 1.6, the angular tolerance is ±1.5°.

[0014] Preferably, the first transmitting unit, the second transmitting unit, the first detector unit and the second detector unit are arranged relative to each other so that a first connecting line extending from the first transmitting unit toward the second detector unit intersects a second connecting line in the measuring area of ​​the substrate, and the second connecting line extends from the second transmitting unit toward the first detector unit.

[0015] The first connecting line and the second connecting line therefore essentially correspond to the transmission beam path of the directed electromagnetic radiation emitted by the respective transmitting unit.

[0016] Parallel deviations of the transmitted beam path due to refraction effects in the substrate are not considered with respect to the first connecting line or the second connecting line, since these can be compensated for and thus tolerated by arranging the first detector unit or the second detector unit in the corresponding measuring cell.

[0017] The first and / or second detector units can include a visible light (VIS) spectrometer and / or a near-infrared (NIR) spectrometer. Thus, the respective detector units can be configured to detect electromagnetic radiation in the visible and near-infrared ranges of the spectrum. These wavelength ranges are particularly important for determining the properties of optically transparent substrates in order to check their suitability for intended applications. Detection with the aid of a visible light spectrometer allows, for example, the optical appearance of a coated substrate in the human eye, such as the color impression, to be determined. Using a near-infrared spectrometer, information about the thermal properties of the coated substrate can be obtained.

[0018] The first detector unit and / or the second detector unit may comprise sensor elements, by means of which electromagnetic radiation impinging from the substrate onto the respective detector unit may be detected, wherein in particular an intensity distribution may be determined depending on the wavelength of the incident electromagnetic radiation.

[0019] The sensor element may comprise a homogenization device, by means of which the electromagnetic radiation impinging on the sensor element may be homogenized.

[0020] The homogenized electromagnetic radiation can then be detected in a sensor of the sensor element.

[0021] For example, a homogenization device includes a collector and a homogenizer connected downstream of the collector along the optical path. The collector and homogenizer are arranged relative to each other so that the inlet opening of the homogenizer coincides with the focal point of the collector. This allows the size of the inlet opening of the homogenizer to be minimized, further reducing the influence of scattered light. In other words, the angular tolerance of the corresponding detector unit, i.e., the angular range within which electromagnetic radiation from the substrate can contribute to the detected signal, can be determined solely by the size of the inlet opening.

[0022] The homogenization device, in particular its homogenizer, has an exit opening through which the homogenized electromagnetic radiation can leave the homogenization device and reach the sensors of the sensor element, which are ultimately used for detection.

[0023] To further increase the measuring speed of the device, a switching element can be associated with the first and / or second transmitting unit, by means of which the source of electromagnetic radiation can be connected in order to actively switch the first or second transmitting unit. In particular, the switching element can be integrated into the corresponding transmitting unit. This design eliminates the need to switch the source of electromagnetic radiation itself on or off when the device switches from the first operating mode to the second operating mode. Instead, the time offset that must be observed when switching the operating mode of the device can be selected solely via the switching times of the switching elements used.

[0024] Preferably, the switching element has a switching time of 30 ms or less, in particular a switching time of 10 ms or less. Switching elements with corresponding switching times are known. For example, the switching element can be a fiber optic switch.

[0025] Fiber optic switches, also known as fiber switches, are characterized by extremely short switching times at high cycle rates. They have one or more piezoelectric actuators. The respective piezoelectric actuators establish or disconnect the connection between the fiber ends of the fiber optic switch. The fiber ends to be connected or disconnected are respectively associated with a connection point or output end of the fiber optic switch.

[0026] The optical fiber switch may have one or more connection locations to which a source of electromagnetic radiation is connected. In particular, the device may comprise a plurality of sources of electromagnetic radiation, wherein each of the plurality of sources of electromagnetic radiation is connected to another connection location.

[0027] Furthermore, the fiber optic switch can have one output or a plurality of outputs, which are connected to a transmitting unit associated with the fiber optic switch.

[0028] Of course, the fiber optic switch can also have a different number of connection points and output ends, for example, a plurality of connection points and a single output end.

[0029] Fiber optic switches are also characterized by a high attenuation between the connection channels, which is produced by connecting the corresponding fiber ends, so that the respectively established connection is not influenced, or at least as little as possible, by other available optical fibers of the fiber optic switch.

[0030] It goes without saying that the fiber optic switch must be at least partially transparent at least for the portion of the electromagnetic radiation generated by one or more sources of electromagnetic radiation and to be emitted by the respectively associated transmitting unit. For example, the fiber optic switch has an operating wavelength range of 250 nm to 2500 nm, in particular 275 nm to 2100 nm.

[0031] In particular, the switching frequency of the fiber optic switch is in the range of 0.005 Hz to 30 Hz, for example, 0.01 Hz to 20 Hz. In this way, the switching process can be repeated by the fiber optic switch even after a short time delay. The measurement region can have a length of 30 mm or less, in particular 20 mm or less, for example 12 mm or less. In this way, it is possible to determine the optical properties of the substrate particularly accurately, because the measurement data obtained in the measurement represent a relatively small region of the substrate, thereby minimizing or eliminating errors by averaging the measurement data. A measurement region of this length can be achieved by the design according to the invention and coordination between the first transmitting unit, the first detector unit, the second transmitting unit, and the second detector unit.

[0032] The geometric shape of the measurement region on the substrate surface, i.e., its cross-section, is not subject to further restrictions. For example, the measurement region can be circular, elliptical, square, or rectangular. In any case, the length of the measurement region refers to the extent of the measurement region along the direction in which the measurement region is at its largest.

[0033] In one variant, the first measuring unit and / or the second measuring unit comprises a third transmitting unit for irradiating the measuring region of the substrate with directed electromagnetic radiation, and a third detector unit associated with the third transmitting unit. The third transmitting unit is arranged relative to the first side or the second side of the substrate such that the emitted electromagnetic radiation has a third emission angle relative to a normal to the first side or the second side of the substrate.

[0034] The third emission angle can be selected flexibly depending on which property of the coated substrate is to be determined using the measurement data obtained in the third detector unit.

[0035] In particular, the third emission angle lies in the range of 45° to 65°.

[0036] The optical properties of a coated substrate can vary significantly depending on the angle from which it is viewed. The third emission unit enables reliable determination of the substrate's appearance even at relatively steep angles relative to the substrate's surface. This makes it possible to determine, in particular, the color of the optical substrate on the first or second side.

[0037] Furthermore, it can be checked in this manner that the coated substrate does not exhibit a so-called "flip" effect. This is understood to mean that the optical impression, in particular the color impression, produced by the coated substrate on the observer changes significantly or abruptly with relatively small changes in the viewing angle.

[0038] It goes without saying that the third transmitting unit can be associated not only with the first side, in particular as a component of the first measuring unit, but also with the second side, in particular as a component of the second measuring unit. The third transmitting unit can also be integrated into both the first measuring unit and the second measuring unit.

[0039] In order to be able to achieve an optimal measurement depending on the application, the third emission unit can be adjusted in steps or continuously. In this way, the color impression can be determined at different observation angles via the third emission unit.

[0040] The time at which the third transmitting unit is activated can be selected flexibly. For example, the third transmitting unit can be active in the first operating mode and / or the second operating mode. Because the third transmitting angle deviates (significantly) from the first and second transmitting angles, for example by more than 40°, the electromagnetic radiation emitted by the first transmitting unit, the second transmitting unit, and the third transmitting unit is not affected or is only insignificantly affected.

[0041] The electromagnetic radiation preferably has a wavelength in the range of 350 nm to 2500 nm, for example, in the range of 350 nm to 1600 nm, preferably in the range of 350 nm to 1200 nm, and more preferably in the range of 380 nm to 1000 nm. At wavelengths below 350 nm, UV characteristics of the coated substrate have been measured, which are not significant for the impression the coated substrate creates when the optical substrate is observed with the human eye. Wavelengths above 2500 nm are technically difficult to achieve. Furthermore, measurements at wavelengths above 2500 nm may result in larger error margins due to ambient thermal influences.

[0042] Furthermore, at least one measuring head can be provided, which has a first measuring unit and / or a second measuring unit, wherein the measuring head can be moved along the substrate.

[0043] In this way, the optical properties of the coated substrate can be measured at different positions of the coated substrate. In addition, if the substrate moves within the device, the measuring head can follow the substrate, so that the smallest possible measurement area is also achieved in this case.

[0044] The apparatus can include a transport device by which the substrates can be moved in the processing direction, in particular, the substrates can be moved in the processing direction at a speed of several meters per minute. For example, the speed at which the substrates can be moved in the processing direction is in the range of 9 m / min to 25 m / min. In this way, the throughput of the coated substrates being inspected in the apparatus according to the invention can be increased and the handling of the coated substrates within the apparatus can be facilitated.

[0045] Preferably, the transport device is combined with the above-described movable measuring head, wherein the movement of the measuring head is coordinated with the movement of the substrate.

[0046] The measuring head preferably has a traversing speed that is equal to or greater than the speed at which the substrate moves in the processing direction. For example, the measuring head speed is up to 800 mm / s, preferably up to 600 mm / s. However, it goes without saying that the traversing speed of the measuring head only needs to be adapted to the respective measuring method being performed.

[0047] Preferably, the device is configured to determine optical properties of the substrate in a plurality of measurement regions, wherein for each of the measurement regions, at least one measurement in the device's first operating mode and one in the device's second operating mode are performed. In other words, the device is configured to scan the coated substrate. This allows the distribution of properties of the coated substrate over its extent to be determined, from which the homogeneity or uniformity of the coated substrate over the various measurement regions can be determined.

[0048] The measuring head can be moved not only along the transport direction of the substrate, but also in a transverse direction, perpendicular to the transport direction. This allows the optical properties of the substrate to be determined not only along a previously defined line parallel to the transport direction, but also distributed over the substrate. In other words, the measurement area can be arbitrarily selected on the substrate.

[0049] Because the substrate can be moved along the transport direction, it is sufficient to design the measuring head to be movable only in the transport direction and the transverse direction, that is, only in two mutually perpendicular directions of movement. This simplifies the structure and thus reduces the cost of the measuring head and the entire device.

[0050] In this design, for example, multiple measurement areas of a substrate measured in succession can be measured along a measurement line extending obliquely to the transport direction and the transverse direction, which is obtained by combining the movement of the substrate along the transport direction and the movement of the measuring head along the transverse direction.

[0051] It is of course also possible that the measuring head can be moved in any spatial direction in order to be able to more flexibly select the measuring regions to be measured successively.

[0052] In addition, the device can include a unit for measuring the surface resistance of the substrate, in particular for performing eddy current measurements in the measurement region of the substrate. Using the surface resistance, the properties of the substrate can be examined using complementary methods for determining optical properties, in order to determine other parameters of the coated substrate and / or to verify information obtained using the detector unit. For example, the crystal structure of the substrate and / or its coating can be inferred using eddy current measurements.

[0053] The object of the invention is also achieved by a coating plant for producing an optically transparent substrate having a substrate coating applied on a first side thereof, the coating plant comprising an apparatus as described above for determining optical properties of an optically transparent substrate.

[0054] The properties and features of the device according to the invention apply correspondingly to the coating installation according to the invention, and vice versa, and reference is made to the above explanations.

[0055] The device for determining the optical properties can be connected directly to the cladding modules of the cladding installation or can be physically separated from the cladding installation.

[0056] In one variant, the device for determining optical properties is integrated into the coating system, allowing the optical properties of optically transparent substrates to be checked during the coating process. For example, a measurement area is selected in a coated portion of the substrate, while another portion of the substrate is coated upstream in the coating system's processing direction. This variant makes it possible to adjust the coating process based on specific optical properties.

[0057] In an alternative and preferred variant, the device for determining optical properties is a separate facility module of the coating facility, so that the device for determining optical properties is not influenced by other modules of the coating facility. In other words, the device according to the invention is used in particular as an "ex situ" measurement device. Furthermore, this design allows the production of the coated substrate to be separated temporally and / or spatially from the determination of the optical properties of the coated substrate, thereby increasing flexibility in the method for producing the coated substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Further features and characteristics of the invention are apparent from the following description of exemplary embodiments, which are not to be understood as limiting, and from the accompanying drawings, to which reference is made. In the drawings:

[0059] Figure 1 shows a cladding installation according to the invention,

[0060] Figure 2 A device for determining an optical property according to the invention is shown, as described in Figure 1 As used in cladding facilities,

[0061] Figure 3 Shown in the first operating mode Figure 2 The equipment in

[0062] Figure 4 Shown in the second operating mode Figure 2 The equipment in

[0063] Figure 5 Shown with Figure 2 A similar further embodiment of the device according to the invention, and

[0064] Figure 6 Show Figure 2 Schematic diagram of selected parts of the detection unit of the device. DETAILED DESCRIPTION

[0065] Figure 1 A coating installation 10 for applying a substrate coating 12 to an optically transparent substrate 14 is schematically shown (see FIG. Figure 2 ).

[0066] Substrate 14 is composed of, for example, glass or plastic and is substantially flat. For example, substrate 14 is a plate having a rectangular cross-section and external dimensions of up to 4 meters by 9 meters. However, as long as substrate 14 is optically transparent and can be handled by coating facility 10, there are no further limitations on the type and shape of the substrate.

[0067] Hereinafter, the substrate 14 provided with the substrate cover 12 is also referred to as a “covered substrate 14 ”.

[0068] The coating installation 10 has a loading module 16 , a coating module 18 , a cleaning module 20 and an unloading module 22 , which are arranged one after another along a processing direction B.

[0069] The loading module 16 serves to load the substrate 14 onto a roller arrangement 23 of the coating installation 10 , by means of which the substrate 14 can be moved in the processing direction B.

[0070] In the coating module 18, a substrate coating 12 is applied to the substrate 14. The type of substrate coating 12 is not further limited as long as the coated substrate 14 is also optically transparent. For example, the substrate coating 12 is an anti-reflective coating, a thermal coating, and / or a protective coating.

[0071] In the cleaning module 20 , any residues from the coating process in the coating module 18 are removed.

[0072] The coated substrate 14 can be removed in the unloading module 22 , for example, by means of a removal mechanism (not shown).

[0073] Figure 1 The number and types of modules of the cladding installation 10 shown in FIG. 1 are merely exemplary, so that other and / or additional modules may of course also be present in the cladding installation 10 .

[0074] Furthermore, the coating installation 10 has a device 24 for determining optical properties of the optically transparent substrate 14 .

[0075] like Figure 1 As schematically shown in FIG, the device 24 is arranged separately from the remaining modules of the coating system 10 so that the device 24 can be operated independently of these modules. Of course, the device 24 can also be integrated into the sequence of the remaining modules of the coating system 10 along the processing direction B. For example, the device 24 can be arranged between the cleaning module 20 and the unloading module 22.

[0076] The device 24 has a transport device 26 , by means of which the substrate 14 can be moved along the processing direction B through the device 24 , for example at a speed of 5 m / min or less.

[0077] Furthermore, the device 24 has a measuring head 28 which comprises a first measuring unit 30 and a second measuring unit 32 .

[0078] The measuring head 28 is connected to a control module 34 in a signal-transmitting manner, so that components of the measuring head 28 can be controlled by means of the control module 34 and measurement data collected by the measuring head 28 can be transmitted to the control module 34 and evaluated by the control module.

[0079] The control module 34 is also configured to control other components of the device 24 .

[0080] exist Figure 2 , selected components of the device 24 and their arrangement relative to the coated substrate 14 are shown in detail.

[0081] As in Figure 2 As can be seen in FIG. 1 , in the illustrated embodiment, the substrate cover 12 completely covers a first side 36 of the substrate 14 , while no substrate cover is present on a second side 38 of the substrate 14 opposite the first side 36 .

[0082] Of course, the substrate 14 may also be different from the Figure 2 . For example, substrate covering 12 can also be applied only to a partial region of first side 36 of substrate 14. Furthermore, substrate covering 12 can also include multiple partial layers. Furthermore, substrate covering 12 can be present not only on first side 36 but also on second side 38 of substrate 14.

[0083] The first measuring unit 30 has a first transmitting unit 40 which is configured to emit directed electromagnetic radiation onto a measuring region 42 of the substrate 14 .

[0084] To this end, first transmitting unit 40 is connected to a first source 44 of electromagnetic radiation, wherein a switching element 46 is provided between first source 44 and first transmitting unit 40, by means of which first source 44 can be switched on. In other words, switching element 46 can determine whether electromagnetic radiation from source 44 reaches first transmitting unit 40 and, therefore, whether first transmitting unit 40 is active or inactive. The switching times of first transmitting unit 40 are therefore determined by the switching times of switching element 46.

[0085] The switching element 46 is preferably a fiber optic switch in order to enable particularly fast switching and in particular to have a switching time of 30 ms or less.

[0086] Furthermore, there is a second source 48 of electromagnetic radiation, which can likewise be switched on via the switching element 46 .

[0087] First source 44 and second source 48 preferably provide electromagnetic radiation of different wavelengths or wavelength ranges, so that electromagnetic radiation directed via first emission unit 40 of different wavelengths can be emitted depending on whether first source 44 and / or second source 48 is switched on via switching element 46 .

[0088] For example, the first source 44 provides electromagnetic radiation having a wavelength in the visible range of the spectrum, and the second source 48 provides electromagnetic radiation having a wavelength in the near infrared range of the spectrum.

[0089] Sources 44 and 48 are, for example, LEDs and / or halogen lamps.

[0090] In principle, instead of a plurality of sources 44 and 48 , there can also be only a single source of the electromagnetic radiation, if this single source alone can provide electromagnetic radiation in the desired wavelength range.

[0091] It goes without saying that the switching element 46 is coordinated with the type and number of sources 44 and 48 used in each case. Thus, the switching element 46 can have one or more connection points for the sources 44 and 48 and one or more outputs, which are connected to the respectively associated transmitting units. Figures 2 to 4 The embodiment shown in FIG. 1 shows a variant in which the switching elements 46 each have a plurality of connection points and a single output.

[0092] exist Figure 5 , a further variant is shown in which the switching element 46 associated with the first transmitting unit 40 has a plurality of connections and a single output, while the switching element 46 associated with the second transmitting unit 58 has a plurality of connections and a plurality of outputs.

[0093] The measuring region 42 has a length of 30 mm or less, wherein said length describes the extent of the measuring region 42 along the direction in which the measuring region 42 is at its largest. Figure 2 In the variant shown in FIG, this is a run parallel to the process direction B.

[0094] The first measuring unit 30 further comprises a first detector unit 50 , which comprises a sensor element 52 (shown only schematically here), a visible light spectrometer 54 and a near infrared spectrometer 56 .

[0095] The sensor element 52 is basically configured to detect electromagnetic radiation incident on the sensor element 52 , wherein the intensity distribution can be determined based on the wavelength of the incident electromagnetic radiation. Based on these measurement data, an evaluation can be performed in a visible light spectrometer 54 (for the visible range of the spectrum) or in a near-infrared spectrometer 56 (for the near-infrared range of the spectrum), which allows inferences to be drawn about the optical properties of the coated substrate 14 .

[0096] In an alternative embodiment, the sensor element 52 may include a homogenization device 70. Figure 6 An exemplary configuration of a homogenization device 70 is schematically shown in FIG.

[0097] The homogenization device 70 has a collector 72 and a homogenizer 74 .

[0098] If electromagnetic radiation (indicated by arrows) impinges on the collector 72 , the incident radiation is focused onto a focal point 75 of the collector 72 .

[0099] An inlet opening 76 of a homogenizer 74 , which is designed as an integrating sphere, for example, is arranged at the focal point 75 . Electromagnetic radiation entering the homogenizer 74 via the inlet opening 76 can leave the homogenizer 74 again via an outlet opening 78 and be guided to a sensor 80 that detects the electromagnetic radiation.

[0100] Figure 6 By way of example, the course of one of the beams incident on the homogenizer 74 via the inlet opening 76 toward the outlet opening 78 is shown. Of course, the actual course depends on the angle of incidence and the design of the inner side of the homogenizer 74 .

[0101] This embodiment makes it possible, in particular, to separate the sensor 80 from the homogenization device 70 for collimating the incident electromagnetic radiation. This further simplifies the design.

[0102] Furthermore, interfering influences caused by scattered light can be further minimized.

[0103] The visible light spectrometer 54 and the near-infrared spectrometer 56 are therefore connected to a sensor 80 which detects the homogenized electromagnetic radiation emerging through the exit opening 78 .

[0104] The second measuring unit 32—analogously to the first measuring unit 30—has a second transmitting unit 58, which is configured to transmit directed electromagnetic radiation onto the same measuring region 42 of the substrate 14 that can also be illuminated by the first measuring unit 30. However, the illumination of the measuring region 42 by the second transmitting unit 58 takes place from the second side 38 of the substrate 14.

[0105] The second transmitting unit 58 is likewise connected to the first source 44 and the second source 48 of electromagnetic radiation via the switching element 46 of the second measuring unit 32 .

[0106] The second transmitting unit 58 also has a second detector unit 60, which, similar to the first detector unit 50, also includes (in Figure 2 ) sensor element 52, a visible light spectrometer 54 and a near infrared spectrometer 56 (shown only schematically in FIG).

[0107] Similar to the first detector unit 50, the second detector unit 60 can also comprise a homogenization device 70, as in Figure 6 As shown in .

[0108] First and second transmitting units 40 and 58 are oriented relative to coated substrate 14 such that electromagnetic radiation emitted by first and second transmitting units 40 and 58 is incident at first and second emission angles α1 and α2 relative to normal 59 to first and second sides 36 and 38 of substrate 14 .

[0109] According to the invention, the first emission angle α1 and the second emission angle α2 are not equal to 0° and are in particular in the range of 3° to 10°, for example 8°.

[0110] Second measuring unit 32 further comprises a third transmitting unit 62, which is also configured to illuminate the same measuring region 42 with electromagnetic radiation as first transmitting unit 40 and second transmitting unit 58. For this purpose, third transmitting unit 62, like second transmitting unit 58, is also connected to first source 44 and second source 48.

[0111] As in Figure 2 As can be seen in FIG, the third transmitting unit 62 is not connected to the first source 44 and the second source 48 via the switching element 46 of the second measuring unit 32. Of course, the third transmitting unit 62 can also have a similar switching element 46.

[0112] It is also possible that the switching element 46 has a plurality of outputs as described above, wherein one of the outputs is connected to the third transmitting unit 62. Figure 5 , wherein the further embodiment further corresponds to Figures 2 to 4 , so that the embodiments of the embodiment are also similarly applicable to the embodiment according to Figure 5 implementation method.

[0113] The second measuring unit 32 furthermore has a third detector unit 64 which is associated with the third transmitting unit 62 and comprises the sensor element 52 and the visible light spectrometer 54 .

[0114] The electromagnetic radiation emitted by the third emission unit 62 impinges on the second side 38 of the substrate 14 at a third emission angle α3 relative to the normal 59, wherein the third emission angle α3 is significantly greater than the first emission angle α1 and the second emission angle α2. For example, the third emission angle α3 is in the range of 45° to 65°.

[0115] Similar to the first detector unit 50 and the second detector unit 60, the third detector unit 64 may also comprise a homogenization device 70, as in Figure 6 As shown in .

[0116] The device 24 further comprises a unit 65 for measuring the surface resistance of the coated substrate 14, i.e., a unit for performing eddy current measurements. The unit 65 comprises two measuring probes 66 and 68, wherein the measuring probe 66 is associated with the first side 36 of the coated substrate 14 and the measuring probe 68 is associated with the second side 38 of the coated substrate 14.

[0117] The unit 65 enables the determination of properties of the coated substrate 14 based on the induction of electric currents in the coated substrate 14 , thereby providing the possibility of determining properties of the coated substrate 14 via methods complementary to optical measurement methods.

[0118] Here, the unit 65 checks the same measurement region 42 that is also illuminated by the emission units 40 , 58 and 62 , for example after the substrate 14 has been moved in the process direction B up to the height of the measuring probes 66 and 68 .

[0119] The control of the unit 65 in coordination with the other measurements can be ensured via the control module 34 , which is likewise connected to the unit 65 in a signal-transmitting manner and controls it.

[0120] The following is based on Figure 3 and Figure 4 The mode of operation of the device 24 according to the invention will be explained in more detail.

[0121] According to the invention, the device 24 has a first operating mode (see Figure 3 ) and the second operating mode (see Figure 4 ). The first operating mode and the second operating mode differ in which of the transmitting units 40 and 58 are active.

[0122] In the first operating mode, the first transmitting unit 40 is active and the second transmitting unit 58 is inactive (see Figure 3In other words, in the first operating mode, the connection between the first transmitting unit 40 and the sources 44 and 48 of the first measuring unit 30 is conducted via the switching element 46 of the first measuring unit 30, while the connection between the second transmitting unit 58 and the sources 44 and 48 of the second measuring unit 30 is blocked via the switching element 46 of the second measuring unit 30.

[0123] Therefore, in the first operating mode, the measurement region 42 is irradiated with electromagnetic radiation exclusively by the first transmitting unit 40. The electromagnetic radiation impinging on the coated substrate 14 partially passes through the coated substrate 14 and is partially reflected by the coated substrate 14, i.e., by the substrate coating 12, resulting in a transmitted beam path (indicated in the figure by arrows) and a reflected beam path (indicated in the figure by dashed arrows).

[0124] The electromagnetic radiation of the transmission beam path impinges on the sensor elements 52 of the second detector unit 60, while the electromagnetic radiation of the reflection beam path impinges on the sensor elements 52 of the first detector unit 50. Thus, according to the invention, in the first operating mode, the transmission and reflection properties of the coated substrate 14 are simultaneously examined when irradiated from the first side 36.

[0125] In the second operating mode, the second transmitting unit 58 is active and the first transmitting unit 40 is inactive (see Figure 4 In other words, in the second operating mode, the connection between the second transmitting unit 58 and the sources 44 and 48 of the second measuring unit 32 is conducted via the switching element 46 of the second measuring unit 32, while the connection between the first transmitting unit 40 and the sources 44 and 48 of the first measuring unit 30 is blocked via the switching element 46 of the first measuring unit 30.

[0126] Therefore, in the second operating mode, the measurement region 42 is irradiated with electromagnetic radiation by the second transmitting unit 58. The electromagnetic radiation impinging on the coated substrate 14 partially passes through the coated substrate 14 and is partially reflected by the coated substrate 14, so that a transmitted beam path (indicated in the figures by dash-dotted arrows) and a reflected beam path (indicated in the figures by dash-dotted arrows) are again obtained.

[0127] The electromagnetic radiation of the transmission beam path impinges on the sensor element 52 of the first detector unit 50, while the electromagnetic radiation of the reflection beam path impinges on the sensor element 52 of the second detector unit 60. Thus, according to the present invention, in the second operating mode, the transmission and reflection properties of the coated substrate 14 are simultaneously examined when irradiated from the second side 38.

[0128] Additionally, in the illustrated embodiment, third transmitting unit 62 is active both in the first operating mode and in the second operating mode, so that measurement region 42 is additionally irradiated with electromagnetic radiation by third transmitting unit 62. This electromagnetic radiation is reflected by second side 38 of substrate 14 and impinges on sensor element 52 of third detection unit 64 (indicated in the drawing by dashed-dash arrows). A color impression can be determined by third detector unit 64, which an observer of substrate 14 receives when observing second side 38 of substrate 14 at an observation angle corresponding to the third emission angle.

[0129] In principle, it is also possible that the third transmitting unit 62 is active only in the first operating mode or only in the second operating mode. For this purpose, the third transmitting unit 62 can be associated with its own switching element 46 as described above, so that the sources 44 and 48 themselves still do not need to be switched on and off.

[0130] Furthermore, it is possible to determine, using the third detector unit 64, any scattered light contribution that occurs when the second transmitting unit 58 is in operation in the second operating mode, in particular if the third transmitting unit 62 is not in operation in the second operating mode. In this manner, the scattered light contribution can be taken into account when evaluating measurements in the second operating mode. If the third detector unit 64 is associated with the first side 36 of the coated substrate 14, the same applies to the first operating mode.

[0131] The switch between the first operating mode and the second operating mode can be performed very quickly and is limited only by the switching time of the switching element 46. Furthermore, the device 24 according to the present invention is characterized by a significant reduction in the total measurement time for determining the optical properties of the substrate 14, since the number of individual measurements to be performed is minimized by the simultaneous determination of the transmission and reflection properties of the coated substrate 14 (from the first side 36 in the first operating mode and from the second side 38 in the second operating mode). Furthermore, this method allows for a relatively small measurement region 42 in which all measurements are performed, allowing the optical properties of the coated substrate 14 to be determined with high local resolution.

[0132] Preferably, the measuring head 28, the first measuring unit 30, the second measuring unit 32 and / or the unit 65 for measuring the surface resistance of the substrate 14 as a whole can be moved along the substrate 14. In this way, on the one hand, different areas of the substrate 14 can be examined, and on the other hand, movements of the substrate 14 along the processing direction B can be compensated in order to minimize the size of the measurement area 42 or to ensure that the same measurement area 42 is examined in different operating modes and by the unit 65. In particular, multiple measurements can also be carried out.

[0133] Overall, the device 24 according to the invention is characterized by a high degree of flexibility in determining the optical properties of the coated substrate 14 and the possibility of realizing particularly small measurement regions.

[0134] Reference Signs List

[0135] 10 Cladding facilities

[0136] 12 Substrate cladding

[0137] 14 substrate

[0138] 16 Loading Module

[0139] 18 Cladding Modules

[0140] 20 Cleaning Module

[0141] 22 Uninstalling modules

[0142] 23 roller device

[0143] 24 Equipment for determining optical properties

[0144] 26 Transport device

[0145] 28 measuring heads

[0146] 30 First measurement unit

[0147] 32 Second measurement unit

[0148] 34 control module

[0149] 36 First side of substrate

[0150] 38 Second side of substrate

[0151] 40 First Launch Unit

[0152] 42 measurement areas

[0153] 44 First Source

[0154] 46 Switching Elements

[0155] 48 Second Source

[0156] 50 First detector unit

[0157] 52 sensor elements

[0158] 54 Visible light spectrometer

[0159] 56 Near-infrared spectrometer

[0160] 58 Second Launch Unit

[0161] 59 Normals

[0162] 60 Second detector unit

[0163] 62 Third Launch Unit

[0164] 64 Third detector unit

[0165] 65 Unit for performing surface resistance measurements

[0166] 66 Measuring probe

[0167] 68 Measuring probe

[0168] 70 Homogenization equipment

[0169] 72 Collector

[0170] 74 Homogenizer

[0171] 75 Focus

[0172] 76 Entering the opening

[0173] 78 exit opening

[0174] 80 sensors

Claims

1. A device (24) for determining optical properties of an optically transparent substrate (14), said substrate being provided with a substrate cover (12) on a first side (36), wherein the device (24) includes a first measurement unit (30) and a second measurement unit (32), wherein the first measurement unit (30) is associated with the first side (36) of the substrate (14) and the second measurement unit (32) is associated with a second side (38) of the substrate (14) opposite the first side (36), wherein the first measuring unit (30) comprises a first transmitting unit (40) for irradiating a measuring region (42) of the substrate (14) with directed electromagnetic radiation and a first detector unit (50), wherein the second measuring unit (32) comprises at least one second transmitting unit (58) for irradiating a measuring region (42) of the substrate (14) with directed electromagnetic radiation and at least one second detector unit (60), The device (24) has a first operating mode and a second operating mode, wherein in the first operating mode, the first transmitting unit (40) is activated and the second transmitting unit (58) is inactivated, and in the second operating mode, the first transmitting unit (40) is inactivated and the second transmitting unit (58) is activated, such that In the first operating mode, electromagnetic radiation reflected by the substrate coating (12) in the measurement region (42) can be detected in the first detector unit (50), and electromagnetic radiation transmitted by the substrate (14) in the measurement region (42) can be detected in the second detector unit (60), and In the second operating mode, electromagnetic radiation reflected by the substrate (14) in the measurement region (42) can be detected in the second detector unit (60).

2. The device (24) according to claim 1, wherein the first emitting unit (40) and / or the second emitting unit (58) is arranged relative to the first side (36) or the second side (38) of the substrate (14) so ​​that the emitted electromagnetic radiation has a first emission angle or a second emission angle in the range of 3° to 10° relative to a normal (59) to the first side (36) or the second side (38) of the substrate (14).

3. The device (24) according to claim 1 or 2, wherein the substrate (14), the first transmitting unit (40), the second transmitting unit (58), the first detector unit (50) and the second detector unit (60) are arranged relative to each other so that a first connecting line extending from the first transmitting unit (40) toward the second detector unit (60) intersects a second connecting line in the measuring area (42) of the substrate (14), and the second connecting line extends from the second transmitting unit (58) toward the first detector unit (50).

4. The device (24) according to any one of the preceding claims, wherein the first detector unit (50) and / or the second detector unit (60) comprises a visible light spectrometer (54) and / or a near infrared spectrometer (56).

5. A device (24) according to any of the preceding claims, wherein a switching element (46) is associated with the first transmitting unit (40) and / or the second transmitting unit (58), by means of which a source (44, 48) of electromagnetic radiation can be switched on in order to actively switch the first transmitting unit (40) or the second transmitting unit (58), in particular, wherein the switching element (46) is integrated into the corresponding transmitting unit (40, 58).

6. The device (24) of claim 5, wherein the switching element (46) has a switching time of 30 ms or less.

7. The device (24) according to any one of the preceding claims, wherein the measuring region (42) has a length of 30 mm or less.

8. The device (24) according to claim 1 , wherein the first measuring unit (30) and / or the second measuring unit (32) comprises a third transmitting unit (62) for irradiating the measuring region (42) of the substrate (14) with directed electromagnetic radiation and a third detector unit (64) associated with the third transmitting unit (14), wherein the third transmitting unit (14) is arranged relative to the first side (36) or the second side (38) of the substrate (14) such that the emitted electromagnetic radiation has a third emission angle relative to the normal (59) to the first side (36) or the second side (38) of the substrate (14), in particular, wherein the third emission angle is in the range of 45° to 65°.

9. The device (24) according to claim 8, wherein the third emission angle is adjustable in steps or continuously.

10. The device (24) according to any one of the preceding claims, wherein the electromagnetic radiation has a wavelength in the range of 350 nm to 2500 nm.

11. The device (24) according to any of the preceding claims, wherein at least one measuring head (28) is provided, the measuring head having the first measuring unit (30) and / or the second measuring unit (32), and wherein the measuring head (28) is movable along the substrate (14).

12. The device (24) according to claim 1, wherein the device (24) comprises a transport device (26) by means of which the substrate (14) can be moved along the processing direction.

13. The device (24) according to claim 12 with reference to claim 11, wherein the device (24) is configured to determine the optical properties of the substrate (14) in a plurality of measurement areas (42), wherein for each measurement area in the measurement areas (42), at least a measurement in a first operating mode of the device (24) and a measurement in a second operating mode of the device (24) are performed.

14. The device (24) according to claim 1 , wherein the device (24) comprises a unit (65) for performing a measurement of the surface resistance of the substrate (14), in particular for performing an eddy current measurement in a measuring region (42) of the substrate (14).

15. A coating facility (10) for producing an optically transparent substrate (14) having a substrate coating (12) applied to a first side (36) of the substrate (14), the coating facility comprising an apparatus (24) for determining optical properties of the optically transparent substrate (14) according to any of the preceding claims.

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