An electrooptical device for a sensing device, an arrangement, as well as a sensing device

Abstract

The present invention relates to an electrooptical device (4) for a sensing device (2), comprising at least one substrate (8) and at least a first electrode (7) on the substrate (8), characterized in that, the first electrode (7) is patterned arranged on the substrate (8), wherein a predefined distance (d) between fingers (9) of the patterned first electrode (7) is selected such, that depending on a current flow through the fingers (9) a heating of the first electrode (7) is performed. Furthermore, the present invention relates to an arrangement (3), as well as to a sensing device (2).

Description

[0001] Description

[0002] An electrooptical device for a sensing device, an arrangement, as well as a sensing device

[0003] The present invention relates to an electrooptical device for a sensing device, comprising at least one substrate and at least a first electrode on the substrate. Furthermore, the present invention relates to an arrangement for a sensing device, as well as to a sensing device.

[0004] Automobile radar sensors are typically operating with radiation in the millimeter wave length range (GHz - THz). There are integrated behind plastic covers in cars, such as the brand emblem or the bumpers. Driving the car in freezing rain or similar meteorological conditions may result in the formation of thick ice layer on the emblem or bumper. This may reduce dramatically the transmission of radiation in the millimeter range radiation and even make the radar operation impossible, comprising thus the safety of the driver.

[0005] Stopping the car and mechanically removing the ice layer from the frozen external surface is not convenient. Using a uniform indium tin oxide (ITO) electrode layer, traditionally used for example in the liquid crystal display industry, to heat that surface is impossible since it introduces very high losses for Gigahertz radiation. Using a heater that surrounds the radar from the periphery is not efficient from the energy point of view.

[0006] Furthermore, it is known that radar sensors are integrated behind plastic covers in motor vehicles, such as the brand emblem or the bumpers. The radars emitted radiation is reflected at the surface of these parts, relating to an attenuation of the transmitted radiation which causes false detection and a decrease of the achievable maximum range and resolution.

[0007] According to the state of the art, automated driving of, for example an SAE level 4 and 5, requires the safe and environmental perception. In general, the motor vehicles environment is detected using different sensors modalities, such as radars, Lidars and cameras. Often, the sensor systems aim for a 360 degree environmental perception and / or detect all static and dynamic objects around the motor vehicle. Lidars are frequently used for precise distance measurements and can also be used for classification purposes. Current approaches for 360 3-dimensional perception require either a multitude of single sensors which are combined or larger sensors which provide a 360 degree detection of the environment. Moreover, Lidar systems can be prone to adversarial weather conditions such as rain, fog or direct light sources. Radar sensors are well established within the automotive industry and provide reliable and robust environmental data. Even in poor visual conditions, such as rain, fog, snow and dust.

[0008] However, a state of the art radom covering the radar sensor from environmental influences or hiding for design reasons the radar, have huge losses to the transmitted radiation in the order larger than 2.5 decibel (db) due to reflection and absorption of the radiation in gigahertz spectral domain.

[0009] US 2017 / 0 334 397 A1 discloses a heater for vehicular sensors, which is configured to pass sensing energy and thereby permit placement of the heater directly over the sensing area in the path of the sensed energy. In this way, direct heating of the sensing area is provided minimizing the energy necessary to prevent icing and improving deicing speed.

[0010] WO 2018 / 109 308 A1 relates to a device for protecting a motor vehicle radar, comprising at least a current generator and a cover, that cover including at least one transmission area through which waves from the radar can travel. The device is characterized in that the transmission area comprises a coating forming an electrical resistor, and in that the current generator can generate a current in the coating.

[0011] DE10 2013 200 364 A1 discloses a body part for a motor vehicle, in particular in the form of a bumper or a bumper strip, that body part being made of plastic and having on its rear side a surface for a sensor, preferable a radar sensor, which can be fitted on the rear side, a heating device in the form of an electrically conductive layer being assigned to this surface.

[0012] It is an object of the present invention to provide an electrooptica I device, an arrangement, as well as a sensing device, by which an improved heating of the electrooptical device is provided.

[0013] This object is solved by an electrooptical device, an arrangement, as well as a sensing device according to the independent claims. Advantageous embodiments are presented in the dependent claims.

[0014] One aspect of the invention relates to an electrooptical device for a sensing device comprising at least one substrate and at least a first electrode on the substrate. According to an embodiment the first electrode is patterned arranged on the substrate, wherein a predefined distance between fingers of the patterned first electrode is selected such, that depending on a current flow through the fingers a heating of the electrode is performed.

[0015] Therefore, the electrooptical device may have a double function, namely that the electrooptical device may generate an electrical field for manipulating sensor beams and also may heat the substrate and therefore deicing may be realized.

[0016] In particular, the invention describes an electrode material with specific sheet resistance range and a spatial pattern of that electrode to be used for the fabrication of heaters for a device operating in the millimeter wave length range. The described material are well- mastered material, for example ITO (Indium-Tin-Oxide), and with the choice of its spatial distribution, in particular its patterning, and the sheet resistance, which provides the most efficient heating with lowest possible radiative losses, this double function can be realized.

[0017] This has the advantage of a low radiation loss and the need of less power. Furthermore, no degradation of resolution and no degradation of range is provided. Furthermore, the material is well-established and a mass produced material. The electrooptical device is easy to integrate with existing radar modules. Furthermore, it is possible for lamination on curved surfaces. Furthermore, an easy customization, in particular resistance, pattern, and losses, for particular radar antennas design may be provided.

[0018] In particular, one of the best transparent electrode materials for visible electrooptical applications may be the thin film material (ITO). With the appropriate choice of the deposition conditions and physical parameters of the film, it may provide rather lower sheet resistance (Rs), for example, as low as 10 Ohm per square. From the other hand, with appropriate thickness of the ITO layer and with index matching layers, this ITO films, in particular the deposited on the substrate, can also provide very low optical or radiative losses, for example at the order of 0.1 percent for the visible range of wave length. This is the reason, why they are widely used in the industry, both as electrooptical electrodes as well as heaters. And the production is very well mastered.

[0019] These materials are now used in the Gigahertz-Terahertz frequency spectrum, but unfortunately, their absorption is very high there. Therefore, it is discovered that one can use the ITO electrodes as heater with low radiative losses for devices operating in the millimeter wave length range, if ITO material with a specific range of heat resistance is used, and if it is a pattern in a specific spatial distribution, in particular specific periodicities.

[0020] The proposed invention is thus based on the elements that a spatial sub-wave length pattern, for example with a period T that is noticeable smaller than the wave length of the radar radiation, and with a special range of the sheet resistance of the ITO electrode, and with a specific orientation of the ITO lanes, for example aligned along the z-axis if the electric field of radiation, in particular emitted and received by the radar, is mostly along the y-axis.

[0021] According to an embodiment the fingers are arranged in the parallel to each other. In particular, the fingers may have a predefined gap to each other and may provide a predefined width. The gap and the width may be provided as the period T. In particular, T may then be the claimed distance. Therefore, a current through the fingers of the electrode may provide a heating and in particular because of the parallel formation the heating is provided for the electrooptical device, in particular for the substrate.

[0022] In another embodiment the fingers are arranged in a serpentine shape. In other words, the fingers may be arranged in a meander form. This has the advantage, that only one electrical contact may be used and on the other hand a big area for heating may be provided.

[0023] In another embodiment the fingers have a predefined width of each finger and a predefined gap between each other. In particular, the gap as well as the width are predefined depending on the material used and the sensing beams, which are received or sent by the sensing device. Therefore, depending on individual parameters, the fingers can be provided.

[0024] In another embodiment at least a second electrode is arranged on the substrate. In particular, with the second electrode and for example with a different operation signal in the first electrode and the second electrode an electrical field between the first electrode and the second electrode may be generated, and therefore a manipulation of sensing beams of the sensing device may be provided.

[0025] In another embodiment fingers of the second electrode and the fingers of the first electrode are arranged interlocked to each other. Therefore, between the interlocked fingers a predefined electrical field can be generated, and therefore an easy way for manipulating sensing beams may be provided. According to another embodiment a first operation signal for the first electrode and a second operation signal, which is different to the first operation signal is provided. In particular according to the serpentine form as well as the interlocked fingers not only a heating is possible, but also the generation of the electric field between these fingers, which can be used for additional electrooptic control. Thus, if the difference of potentials, applied to the first electrode and the second electrode is not zero, then a current is flowing through it with a corresponding heating effect at the first electrode and the second electrode. Furthermore, if the average voltage, applied to the first electrode and the second electrode is different, this can be used to generate the electric field between the two electrodes.

[0026] According to another embodiment, at least the first electrode are comprising a layer of indium tin oxide and / or copper and / or gold and / or silver and / or carbon nanotubes and / or silver nanowires and / or a conductive polymer. This examples are not exhaustive. In particular, one of the frequently used electrode materials for visible electro-optic applications is the thin film of ITO. With appropriate choice of the deposition conditions and the physical parameters of the film, it can provide rather low sheet resistance (Rs), for example, as low as 10 Ohm / Sqaure. From the other hand, with appropriate index matching layers, ITO films, in particular deposited on the substrate, can also provide very low optical or radiative losses, mostly due to the absorption and reflection, for example at the order of 0.2%. According to an advantageous form it may be used at the gigahertz or terahertz frequency spectrum, but unfortunately, their absorption may be very high, such as at the order of 10 db. The losses can be dramatically reduced with the specific choice of the ITO material, in particular the range of the Rs, and its spatial distribution pattern. In particular, the ITO shows excellent transmission when its lines / fingers are along Y-axis, that is, perpendicular to the polarization of the radiation, in particular along X-axis. The loss, in particular introduced by the ITO pattern, is at the order of a fraction of 1 db . Therefore, this gives a significant design freedom for various electro-optic applications.

[0027] In another embodiment the substrate is a transparent substrate. For example, the transparent substrate may be a glass, plastic or a composite substrate. Therefore, different types of substrate may be provided, wherein the electro-optical device is high flexible to be arranged or used.

[0028] In another embodiment the distance is additionally chosen depending on an adhesive between the substrate and the first electrode. In particular, the design of the electrodes must be taken into account, also the geometrical and material parameters surrounding the heater. For example, thermo-conductive adhesive may be used to improve the heat distribution and to avoid the degradation effect due to the fingers shaped electrode pattern. Therefore, an improved manner for operating the electrooptical device is provided.

[0029] Another aspect of the invention relates to an arrangement for a sensing device comprising at least an electrooptical device according to the preceding aspect and at least one electrical field generating device and / or an electrical field receiving device.

[0030] According to an embodiment of the arrangement, the first electrode is arranged essentially perpendicular to the generated and / or received electrical field. In particular, according to this embodiment, the transmission loss is reduced dramatically.

[0031] In another embodiment the arrangement is configured for generating and / or receiving an electrical field in an at least Gigahertz spectrum or higher. Therefore, the arrangement can be used, for example, for radars in order to capture surroundings of, for example, a motor vehicle.

[0032] In another embodiment, the arrangement comprises a plurality of electro-optical devices according to the preceding aspect, wherein the electro-optical devices are stacked. For example, two or more “sandwiches” may be assembled one after another, like a stack, with a possible relative shift, to enhance the diffraction properties of the arrangement.

[0033] Another aspect of the invention relates to a sensing device, comprising at least an arrangement according to the preceding aspect.

[0034] According to an embodiment of the sensing device, the sensing device is configured as a radar sensor.

[0035] Another aspect of the invention relates to a motor vehicle comprising at least the sensing device.

[0036] Advantageous embodiments of the electrooptical device are to be regarded as advantageous embodiments of the arrangement, as well as the sensing device.

[0037] In particular an electronic computing device / computing unit may be provided, for example for generating the operation signals. A computing unit may in particular be understood as a data processing device, which comprises processing circuitry. The computing unit can therefore in particular process data to perform computing operations. This may also include operations to perform indexed accesses to a data structure, for example a look-up table, LUT.

[0038] In particular, the computing unit may include one or more computers, one or more microcontrollers, and / or one or more integrated circuits, for example, one or more application-specific integrated circuits, ASIC, one or more field-programmable gate arrays, FPGA, and / or one or more systems on a chip, SoC. The computing unit may also include one or more processors, for example one or more microprocessors, one or more central processing units, CPU, one or more graphics processing units, GPU, and / or one or more signal processors, in particular one or more digital signal processors, DSP. The computing unit may also include a physical or a virtual cluster of computers or other of said units.

[0039] In various embodiments, the computing unit includes one or more hardware and / or software interfaces and / or one or more memory units.

[0040] A memory unit may be implemented as a volatile data memory, for example a dynamic random access memory, DRAM, or a static random access memory, SRAM, or as a nonvolatile data memory, for example a read-only memory, ROM, a programmable read-only memory, PROM, an erasable programmable read-only memory, EPROM, an electrically erasable programmable read-only memory, EEPROM, a flash memory or flash EEPROM, a ferroelectric random access memory, FRAM, a magnetoresistive random access memory, MRAM, or a phase-change random access memory, PCRAM.

[0041] The sensing device may be used in an electronic vehicle guidance system. An electronic vehicle guidance system may be understood as an electronic system, configured to guide a vehicle in a fully automated or a fully autonomous manner and, in particular, without a manual intervention or control by a driver or user of the vehicle being necessary. The vehicle carries out all required functions, such as steering maneuvers, deceleration maneuvers and / or acceleration maneuvers as well as monitoring and recording the road traffic and corresponding reactions automatically. In particular, the electronic vehicle guidance system may implement a fully automatic or fully autonomous driving mode according to level 5 of the SAE J3016 classification. An electronic vehicle guidance system may also be implemented as an advanced driver assistance system, ADAS, assisting a driver for partially automatic or partially autonomous driving. In particular, the electronic vehicle guidance system may implement a partly automatic or partly autonomous driving mode according to levels 1 to 4 of the SAE J3016 classification. Here and in the following, SAE J3016 refers to the respective standard dated April 2021.

[0042] Guiding the vehicle at least in part automatically may therefore comprise guiding the vehicle according to a fully automatic or fully autonomous driving mode according to level 5 of the SAE J3016 classification. Guiding the vehicle at least in part automatically may also comprise guiding the vehicle according to a partly automatic or partly autonomous driving mode according to levels 1 to 4 of the SAE J3016 classification.

[0043] The sensing device may be configured as environmental sensing system. For example, an environmental sensor system can be understood as a sensor system, which is able to generate sensor data or sensor signals, which depict, represent or image an environment of the environmental sensor system. In particular, the ability to capture or detect electromagnetic or other signals from the environment, cannot be considered a sufficient condition for qualifying a sensor system as an environmental sensor system. For example, cameras, lidar systems, radar systems or ultrasonic sensor systems may be considered as environmental sensor systems.

[0044] Further features of the invention are apparent from the claims, the figures and the figure description. The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of figures and / or shown in the figures may be comprised by the invention not only in the respective combination stated, but also in other combinations. In particular, embodiments and combinations of features, which do not have all the features of an originally formulated claim, may also be comprised by the invention. Moreover, embodiments and combinations of features, which go beyond or deviate from the combinations of features set forth in the recitations of the claims may be comprised by the invention.

[0045] In the following, the invention will be explained in detail with reference to specific exemplary implementations and respective schematic drawings. In the drawings, identical or functionally identical elements may be denoted by the same reference signs. The description of identical or functionally identical elements is not necessarily repeated with respect to different figures.

[0046] Therefore, the drawings show in:

[0047] Fig. 1 a schematic side view according to an embodiment of a motor vehicle comprising an embodiment of a sensing device; Fig. 2 a schematic perspective view according to an embodiment of an electrooptical device; and

[0048] Fig. 3 a schematic top view according to an embodiment of an electrooptical device.

[0049] In the figures the same elements are comprising the same reference signs.

[0050] Fig. 1 shows a schematic side view according to an embodiment of a motor vehicle 1. The motor vehicle 1 comprises a sensing device 2. The sensing device 2 is for example configured as a radar sensor. Alternatively, the sensing device 2 may be configured as a communication device, for example for a communication with a satellite.

[0051] The sensing device 2 comprises at least an arrangement 3. The arrangement 3 comprises at least one electrooptical device 4 and at least one electrical field generation device 5 and / or one electrical field receiving device 6.

[0052] In particular, the electrooptical device 4 may comprise a first electrode 7 (Fig. 2), which may be in particular arranged essentially perpendicular to the generated and / or received electrical field. Furthermore, the arrangement 3 is configured for generating and / or receiving an electrical field in at least a Gigahertz spectrum or higher.

[0053] Fig. 2 shows a schematic perspective view according to an embodiment of the electrooptical device 4. In particular, Fig. 2 shows that the electrooptical device 4 comprises at least one substrate 8 and at least the first electrode 7 on the substrate 8. The first electrode 7 is patterned arranged on the substrate 8, wherein a predefined distance d between fingers 9 of the patterned first electrode 7 is selected such, that depending on a current flow through the fingers 9 a heating of the first electrode 7 is performed.

[0054] Fig. 2 shows in particular, that the fingers 9 are arranged in parallel to each other. Furthermore, Fig. 2 shows, that the fingers 9 have a predefined width w of each finger 9 and a predefined gap g between each other.

[0055] The at least first electrode 7 may comprise a layer of indium tin oxide and / or copper and / or gold and / or silver and / or carbon nanotubes and / or silver nanowires and / or a conductive polymer. Furthermore, the substrate 8 may be a transparent substrate. Furthermore, the distance d is additionally chosen depending on an adhesive between the substrate 8 and the first electrode 7.

[0056] In particular Fig. 2 shows the schematic three-dimensional view of a possible pattern of the ITO layer. Furthermore, contact zones 10 for contacting the electrooptical device 4 with for example an electronic computing device for operating the electrooptical device 7 are provided. Furthermore, contacts 11 to the electronic computing device are shown.

[0057] A key information, necessary for this invention, is the dependence of mm waves’ transmission (or losses) upon the Rs of the ITO. If the ITO layer is uniform, the radiative losses decrease monotonically with the increase of its Rs.

[0058] In general, this dependence is expected since the thickness of the ITO must be increased to reduce its Rs. Thus, one could think that continuously increasing the value of Rs to reduce radiative losses may be beneficial. However, the relative loss measurements, performed by using an ITO pattern, demonstrates the opposite. The patterned ITO with sub wavelength periodicity shows the same tendency for the radiation polarized along the ITO lanes (parallel to y axis). In contrast, losses for the perpendicular direction (when ITO lanes are along the z axis) show the opposite tendency.

[0059] In addition to the loss aspect, also the efficiency of heat generation when using such ITO structures has to be taken into consideration. Here again, the dependence of the efficiency of heat generation is not obvious.

[0060] The achieved temperature elevation also is non-monotonic. Thus, the design with a width of for example w=150 pm and g=150 pm demonstrates an efficient approach. However, the final pattern periodicity must be optimized for a particular radar design, considering the working wavelengths, antennas positions and the required power consumption and the range of temperatures.

[0061] It is important to mention that the operation of the radar is not affected noticeably because of the positioning of these electrodes in front of it.

[0062] Fig. 3 shows a schematic top view according to an embodiment of an electrooptical device 4. In particular Fig. 3 shows the first electrode 7 as well as a second electrode 12. In particular, Fig. 3 shows that fingers 9 of the electrode 7, 12 are arranged in a serpentine shape.

[0063] Furthermore Fig. 3 shows, that fingers 9 of the second electrode 12 and fingers 9 of the first electrode 7 are arranged interlocked to each other. Therefore it is possible, that a first operation signal for the first electrode 7 and a second operation signal 13, which is different to the first operation signal 13, may be provided.

[0064] In particular it is proposed, that a heater uses the linear periodic ITO lanes, in particular the patterned ITO lanes, orientated perpendicular to the electric field of the sensing device radiation, but with a specific sheet resistance Rs as well as a specific width w and gaps g. the pattern, shown in Fig. 3, is only for example. It is also possible to use a serpentine shaped electrode fingers 9 allowing not only the heating but also the generation of the electric field between these fingers 9, which can be used for additional electrooptic control.

[0065] Thus, if the difference of potentials applied to extremities, for example with the first operation signal 13, is not zero, then a current is flowing through it with a corresponding heating effect. The same applies with the second operation signal 14. However, if the average voltage applied with the first operation signal 13 is different from the average voltage applied to the second operation signal 14, then also an electric field between the first electrode 7 and the second electrode 12 is provided.

[0066] Obviously, there is also the question of the substrate 8. The thicker is the substrate 8, higher will be losses. However, fortunately the LCD industry today can handle relatively thin substrates, in particular at the order of 100 micrometers to 200 micrometers. In some cases, the processed substrates can be even 40 micrometer thick. Moreover, thin plastic substrates, such as TPX (polymethylpentene) or PET (Polyethylene terephthalate) can provide additional flexibility and robustness at the same time the losses remain relatively low. Thus, with an appropriate choice of the ITO pattern, in particular the width w and the gap g, its sheet resistance Rs and the substrate, in particular material thickness, an efficient heater for Gigahertz to Terahertz radiation devices can be provided.

[0067] It is further important to mention that the design of the electrodes 7, 12 must be made taken into account also the geometrical and material parameters surrounding the heater. For example, thermo-conductive adhesive may be used to improve the heat distribution and to avoid the degradation effect due to fingers-shaped electrode pattern. Reference list

[0068] 1 Motor vehicle

[0069] 2 Sensing device

[0070] 3 Arrangement

[0071] 4 Electrooptical device

[0072] 5 Electrical field generating device

[0073] 6 Electrical field receiving device

[0074] 7 First electrode

[0075] 8 Substrate

[0076] 9 Finger

[0077] 10 Contact elements

[0078] 11 Contacts

[0079] 12 Second electrode

[0080] 13 First operation signal

[0081] 14 Second operation signal d Distance g Gap w Width'

Claims

Patent Claims1. An electrooptical device (4) for a sensing device (2), comprising at least one substrate (8) and at least a first electrode (7) on the substrate (8), characterized in that, the first electrode (7) is patterned arranged on the substrate (8), wherein a predefined distance (d) between fingers (9) of the patterned first electrode (7) is selected such, that depending on a current flow through the fingers (9) a heating of the first electrode (7) is performed.

2. The electrooptical device (4) according to claim 1, characterized in that the fingers (9) are arranged in parallel to each other.

3. The electrooptical device (4) according to claim 1 or 2, characterized in that the fingers (9) are arranged in a serpentine shape.

4. The electrooptical device (4) according to any of claims 1 to 3, characterized in that the fingers (9) have a predefined width (w) of each finger (9) and a predefined gap (g) between each other.

5. The electrooptical device (4) according to any of claims 1 to 4, characterized in that at least a second electrode (12) is arranged on the substrate (8).

6. The electrooptical device (4) according to claim 5, characterized in that fingers (9) of the second electrode (12) and the fingers (9) of the first electrode (7) are arranged interlocked to each other.

7. The electrooptical device (4) according to claim 5 or 6, characterized in thata first operation signal (13) for the first electrode (7) and a second operation signal (14), which is different to the first operation signal (13), for the second electrode (12) is provided.

8. The electrooptical device (4) according to any of claims 1 to 7, characterized in that at least the first electrode (7) is comprising a layer of Indium Tin Oxide and / or copper and / or gold and / or silver and / or carbon nano tubes and / or silver nano wires and / or a conductive polymer.

9. The electrooptical device (4) according to any of claims 1 to 8, characterized in that the substrate (8) is a transparent substrate (8).

10. The electrooptical device (4) according to any of claims 1 to 9, characterized in that the distance (d) is additionally chosen depending on an adhesive between the substrate (8) and the first electrode (7).

11. An arrangement (3) for a sensing device (2) comprising at least an electro optical device (4) according to any of claims 1 to 10 and at least one electrical field generating device (5) and / or an electrical field receiving device (6).

12. The arrangement (3) according to claim 11 , characterized in that the first electrode (7) is arranged essentially perpendicular to the generated and / or received electrical field.

13. The arrangement (3) according to claim 11 or 12, characterized in that the arrangement (3) is configured for generating and / or receiving an electrical field in at least a GHz-Spectrum or higher.

14. A sensing device (2), comprising at least an arrangement (3) according to any of claims 11 to 13.

15. A sensing device (2) according to claim 14, characterized in that the sensing device (2) is configured as a radar sensor.

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