Optical arrangement and method for operating an optical arrangement

Abstract

The optical arrangement (1) comprises a radiation-transmissive disk (2) and a piezoelectric excitation element (3). The excitation element (3) is arranged on a first main side (21) of the disk (2). The radiation-transmissive disk (2) has a central region (4) and an edge region (5) surrounding the central region. The excitation element (3) is designed to excite at least one rotationally symmetric bending mode in the central region (4) of the radiation-transmissive disk (2). The excitation element (3) is further designed to excite at least one non-rotationally symmetric bending mode in the edge region (5) of the radiation-transmissive disk (2), which generates a traveling wave in the edge region (5).

Description

The invention relates to an optical arrangement and to a method for operating such an optical arrangement.In camera applications, in particular in outdoor applications, it is typically desirable that they provide satisfactory images even in the case of rain or after soiling. This is the case in particular when the camera is used in the automotive sector. If, for example, the camera is part of a sensor or of a lidar system for an automobile, there is a need for a camera that functions well even under poor weather conditions in order to increase or ensure vehicle auto-driving. In the external area, the camera can be, for example, a surveillance camera. There is therefore a basic need to be able to clean the camera in order to remove rain or dirt from a cover or a lens of the camera.Conventional cleaning systems are based on a cleaning effect of water nozzles and / or mechanical wiping systems. Alternatively, the camera can be cleaned with ultrasound. Such a method is also known as "Ultra Sonic Lens Cleaning". Typically, a cover of the camera is vibrated so as to scatter the water thereon or to form a thin film of vapor between the surface of the cover and the water, so that the water can be easily ablated. Typically, the cover is only caused to oscillate in a central region, while the cover remains virtually at rest in an edge region. In other words, an excited bending mode in the cover has nodes at the edges of the cover or in the edge region. Since an edge region is thus typically free of oscillations or vibrations, this leads to impairment of a recording quality of the camera and, for example, in the application of autonomous driving, vehicle auto-driving may be insufficient.U.S. Pat. No. 10,682,675 B2 describes a system for lens cleaning by means of ultrasound.An object to be achieved is to provide an improved optical arrangement which can function as a cover for a camera or a camera lens and enables improved cleaning in the edge region. A further object to be achieved is to specify a method for operating such an optical arrangement.These objects are achieved by an object having the features of independent claim 1 and by a method having the features of claim 19. Advantageous refinements and refinements are the subject matter of the respectively dependent patent claims.An optical arrangement is proposed which has a radiation-transmissive disc and a piezoelectric excitation element. The excitation element is arranged on a first main side of the pane. The radiation-transmissive pane has a central region and an edge region encircling the central region. The excitation element is configured to excite at least one rotationally symmetrical bending mode into the central region of the radiation-transmissive disc. The excitation element is furthermore configured to excite at least one non-rotationally symmetrical bending mode in the edge region of the radiation-transmissive disc, which bending mode generates a revolving wave in the edge region.The radiation-transmissive pane is, for example, a cover for a camera or a camera lens. This means that the pane is arranged in particular in front of the camera or the camera lens and protects it from external influences such as rain or dirt. The optical arrangement is in particular a lens cleaning system for a camera lens or the like."Radiation-transmissive" here and below means that the pane is transmissive for incident electromagnetic radiation, such as visible light, for example. In particular, at least 70% or at least 80% or at least 90% or preferably at least 95% of the incident radiation is transmitted through the pane. In particular, the pane is radiation-transmissive in a wavelength range in which a camera arranged downstream, for example, is sensitive. If the camera is, for example, a camera for an infrared sensor, the pane is preferably radiation-transmissive for electromagnetic radiation in the infrared wavelength range. The pane comprises, for example, a glass, a polymer and / or a laminated glass. The glass includes, for example, a silicate glass, borosilicate glass such as K9 glass (borosilicate), and / or an aluminosilicate glass. The glass for the pane is preferably scratch-resistant and has anti-reflection properties.The excitation element is in particular a piezoelectric excitation element and is preferably formed with a ceramic such as a piezoceramic. That is, by applying an electrical voltage, the excitation element can spatially deform, in particular expand or contract. Thus, by applying an electric voltage, a mechanical movement can be excited in the excitation element, which can be transmitted to the pane.If a corresponding voltage is excited during operation of the optical arrangement, then a vibration, in particular a bending vibration, can be excited in the pane by means of the excitation element. The bending oscillation preferably has a plurality of modes.During operation, the disk is excited by means of the excitation element in such a way that at least one rotationally symmetrical bending mode is generated in the central region of the disk. An associated deformation of the disk in the central region, which is attributed to the rotationally symmetrical bending mode, is in particular rotationally symmetrical. For example, the deformation is greatest at the center of the disk and then falls off uniformly in the direction of the edges. In particular, a deformation which originates from the rotationally symmetrical bending mode is such that it is not present or is substantially not present in the edge region. This means that by means of the rotationally symmetrical bending mode, no movement or essentially no movement of the pane is excited in the edge region. If, therefore, during operation only the at least one rotationally symmetrical bending mode were excited, the edge region of the pane would be substantially at rest. Thus, disadvantageously, no cleaning effect can be achieved in the edge region, since a vibration or vibration of the pane is necessary for the latter.Therefore, the excitation element is advantageously further configured to generate at least one non-rotationally symmetrical bending modes in the edge region. These non-rotationally symmetrical bending modes set the pane in vibration or vibration in the edge region, in which deformation of the pane in the edge region is excited. In this case, a plurality of bending modes, preferably exactly three bending modes, can be superimposed, so that a moving wave is generated in the edge region.A "running wave" is understood here and below to mean a wave which, in contrast to a standing wave, does not have any fixed nodes. With the wave running in the edge region, the nodes travel along a contour of the disk. Thus, during operation of the optical arrangement of the optical arrangement, each region or substantially each region of the pane in the edge region is deformed and set in vibration, so that effective cleaning in the edge region is possible. The traveling wave results in particular from a combination of a plurality of bending modes, preferably exactly three bending modes.The edge region preferably completely encloses the edge region in lateral directions. Lateral directions extend parallel to a main extension plane of the pane. The edge region differs from the central region in particular in that no deformation or substantially no deformation can be excited in the edge region by means of the rotationally symmetrical bending mode. For example, in the edge region, a maximum amplitude of the bending vibration excited by the rotationally symmetrical bending mode falls to a value of 1 / e times its maximum value.During operation, the rotationally symmetrical bending mode and the non-rotationally symmetrical bending modes can preferably be superimposed. Such superposition advantageously results in a complex movement of the pane and a corresponding deformation and flexural vibration. As a result of this periodic movement or vibration, the pane can be set in movement or vibration substantially in all regions, with the result that effective cleaning of the pane is possible both in the edge region and in the central region.The radiation-transmissive disc is preferably circular. The excitation element is preferably ring-shaped, i.e. designed as a ring. An outer diameter of the annular excitation element may substantially correspond to a diameter of the circular disk. For example, the circular disc has a diameter of 15 mm to 25 mm, for example 21 mm. The diameter is measured in particular in a direction parallel to the first main side. A thickness of the pane is, for example, between 1 and 2 mm, for example 1.5 mm.An outer diameter of the excitation element is, for example, between 15 mm and 25 mm, for example 21 mm, and an inner diameter is, for example, between 13 mm and 18 mm, for example 15 mm. A thickness of the excitation element may correspond to a thickness of the disk. The thickness of the excitation element is, for example, between 1 mm and 2 mm, for example 1.5 mm.In particular, in view of the first main side of the pane, the excitation element at least partially covers the edge region of the pane. It is possible for the edge region to be completely covered by the excitation element in view of the first main side.In a preferred embodiment, the excitation element comprises a plurality of front-side contact regions on a front side facing the first main side of the pane. The front-side contact regions can be electrically contacted and / or operated in particular independently of one another. The front-side contact regions may be formed with a thin metal layer on the front side of the excitation element. The front-side contact regions can be produced, for example, by means of sputtering. For example, the front side contact regions comprise a metal or a metal alloy such as copper or aluminum or gold.During normal operation, a voltage can be applied to the front-side contact regions, by means of which voltage the excitation element can be deformed and can excite a movement or deformation in the pane. In this case, different voltages can be applied to different front-side contact regions.For example, the front-side contact elements can comprise front-side contact elements of the first type, of the second type and of the third type. For example, during operation, a first voltage is applied to the front-side contact elements of the first type, a second voltage is applied to the front-side contact elements of the second type, and a third voltage is applied to the contact elements of the third type. The first, second and third voltages are, for example, harmonic alternating voltages with fixed amplitude and frequency. By applying three different voltages, in particular a plurality of non-rotationally symmetrical bending mode modes can be excited in the edge region. The running wave can thus preferably be generated in the edge region. In this case, in particular, a non-rotationally symmetrical bending mode is excited in the pane by each of the three stresses. Superposition of these three bending modes advantageously results in the running wave in the edge region.The first voltage, the second voltage, and the third voltage each preferably have an amplitude and a frequency. A first amplitude of the first, second and third voltages is in particular identical and is, for example, 10 V. A first frequency of the first, second and third voltages is in particular identical and is, for example, approximately 17 kHz.The first, second and third voltages differ in particular only by a phase offset. A phase offset of the second voltage to the first voltage is, for example, 120°. A phase offset of the third voltage with respect to the first voltage is, for example, 240°. The phase offset can also be chosen differently, whereby, for example, the direction of the current wave can be predefined.With the above-mentioned first amplitude and first frequency, two wave trains can be excited in the edge region. This means that a generated wave in the edge region has two maxima and two minima, which travel along the contour of the pane in the edge region.If, on the other hand, 10 V is selected as the second amplitude and approximately 39 kHz is selected as the second frequency, then three wave trains result for the rotating wave in this example. In this case, the moving wave thus has three maxima and three minima in the edge region. The values mentioned for the first / second amplitude and the first / second frequency are to be regarded as purely exemplary. In the application, these values are to be adjusted in particular in order to adapt a damping of the resulting bending vibration to a load, for example, that is to say in particular a quantity of water on the lens. The resonant frequency of the induced oscillation can also shift.By applying a fourth voltage to all front-side contact regions, the rotationally symmetrical bending mode can be excited. The fourth voltage is, for example, harmonic alternating voltages with fixed amplitude and frequency. The amplitude is, for example, 10 V and the frequency is, for example, about 35 kHz. The voltage is preferably identical for all front-side contact regions, i.e. it does not have a phase offset between the front-side contact regions of the first, second or third type.During normal operation, these voltages for the contact region of the first type, second type and third type can be superimposed. This results in particular in an applied voltage for the front-side contact region of the first type, which is a combination of the first and fourth voltages. For the front-side contact region of the second type, a voltage results which is a combination of the second voltage and the fourth voltage, and for the front-side contact region of the third type, a voltage results which is a combination of the third and the fourth voltage. It may be necessary to adapt the amplitudes and frequencies of the first, second, third voltages, in particular in order to achieve a sufficiently homogeneous acceleration of the pane during operation. For example, the first amplitude is adjusted to 50 V and the second amplitude to 100 V. The first frequency may be adjusted to about 40 kHz and the second frequency may be adjusted to about 17 kHz.The values mentioned for the amplitude of the fourth voltage and the first / second amplitude and the frequency of the fourth voltage and the first / second frequency are to be regarded as purely exemplary. In the application, these values are to be adjusted in particular in order to adapt a damping of the resulting bending vibration to a load, for example, that is to say in particular a quantity of water on the lens. The resonant frequency of the induced oscillation can also shift.In a preferred development, the excitation element has a plurality of rear-side contact regions on a rear side facing away from the first main side of the pane. The rear-side contact regions can preferably be electrically actuated and / or operated independently of one another. Via the rear contact regions, deformations or oscillations can be induced in the pane by applying a voltage. The rear-side contact regions comprise, for example, a metal or a metal alloy. In particular, the rear-side contact regions comprise the same materials as the front-side contact regions and are applied by the same methods.The rear side contact regions may be provided in addition to the front side contact regions. However, it is also possible for the excitation element to have only rear-side contact regions.If, for example, only contact regions are present on the rear side, that is to say in the case that the excitation element on the front side is free of contact regions and has only rear-side contact regions, then the rear-side contact regions can preferably be contacted in a similar or similar manner to the front-side contact regions in the example explained above.If, on the other hand, front-side and rear-side contact regions are present, it is advantageously possible to apply a modified first voltage, a modified second voltage and a modified third voltage to the front-side and rear-side contact elements. The amplitude of the modified voltages can be selected to be lower by a factor of less than the amplitudes of the corresponding first, second and third voltages.For example, the rear-side contact regions likewise comprise rear-side contact regions of the first type, of the second type and of the third type, it being possible for the first or the modified first voltage to be applied to the rear-side contacts of the first type, the second or the modified second voltage to be applied to the rear-side contact regions of the second type and the third or the modified third voltage to be applied to the rear-side contact regions of the third type.A phase offset of the first voltage, second voltage and third voltage, and the modified first voltage, the modified second voltage and the modified third voltage, respectively, may be selected as described above.Preferably, the front-side contact regions can be electrically contacted and / or operated independently of the rear-side contact regions.For example, in a projection into a common plane parallel to the front side, the front-side contact regions are arranged offset from the rear-side contact regions. Alternatively, it is possible for the front-side contact regions and the rear-side contact regions to be congruent or substantially congruent with respect to one another in this projection. The common plane may include the front side or the back side.If the front-side and rear-side contact regions are arranged offset with respect to one another, then, in the projection into the common plane, each front-side contact region, for example, overlaps with at least two rear-side contact regions. It has surprisingly been found that the number of contact regions can be reduced in this way without influencing the excitation of a plurality of non-rotationally symmetrical bending modes.For example, for excitation of two wave trains, the excitation element has in each case two front-side contact regions of the first type, of the second type and of the third type. In addition, the excitation element can each have two rear-side contact regions of the first type, of the second type and of the third type. In an offset arrangement, the excitation element advantageously has, for example, only a front-side contact region of the first type, second type and third type and a rear-side contact region of the first type, second type and third type. In this case, the stimulable standing wave has two wave trains in the edge portion.If three wave trains are to be excited during normal operation, then in an offset arrangement the excitation element has, for example, in each case two contact regions of the first and third type and one contact region of the second type. In comparison thereto, in the case of an offset arrangement the excitation element has in each case two front-side contact regions of the first type, of the second type and of the third type.In the case that the excitation element has only front-side contact regions or rear-side contact regions, the excitation element preferably has a ground contact on a side which is opposite the contact regions. The ground contact can be formed by the entire corresponding front side or rear side. If, for example, the excitation element has only front-side contact regions, the ground contact is formed on the rear side and can be formed by the rear side. If, on the other hand, the excitation element has, for example, only rear-side contact regions, then the ground contact is preferably formed on the front side.A distance between two adjacent front-side contact regions and / or two adjacent rear-side contact regions is, for example, between 0.2 mm and 1 mm inclusive.Alternatively or additionally, a distance between two front-side contact regions and / or two adjacent rear-side contact regions is between one third and one half of a thickness of the excitation element. The excitation element has, for example, a thickness between 0.2 mm and 1.7 mm inclusive, preferably between 0.2 mm and 0.7 mm inclusive. The thickness of the excitation element is, for example, 0.5 mm or approximately 0.5 mm. By such a distance between the contact regions, dropping below a coercive field strength can be prevented. A risk of local overheating of the excitation element during operation can thus be significantly reduced.In a further preferred embodiment, the excitation element has at least one front-side contact region and at least one rear-side contact region. On a side surface of the excitation element, the excitation element preferably has at least one metallization which connects the at least one front-side contact region and the at least one rear-side contact region to one another in an electrically conductive manner. The metallization thus forms a contacting of the excitation element. The side surface connects the front side of the excitation element to the rear side of the excitation element.The front-side contact region can be, for example, a front-side contact region of fourth type, which is electrically conductively connected to the ground contact. The ground contact can thus be electrically conductively contacted from the front side. Alternatively, it is possible for the front-side contact region to be electrically conductively connected to a rear-side contact region of the first type, of the second type or of the third type.It is likewise possible for a plurality of contact regions, each of which is electrically conductively connected to a side-surface metallization, to be arranged on the front side. For example, the front side has front side contact regions of fourth type, fifth type and sixth type, wherein the front side contact regions of fourth type are electrically conductively connected to rear side contact regions of first type via a first side-surface metallization. In an analogous manner, the front-side contact regions of the fifth type can be electrically conductively connected to the rear-side contact regions of the second type via a side-surface second metallization, and the front-side contact regions of the sixth type can be electrically conductively connected to the rear-side contacts of the third type via a side-surface third metallization. That is, in this case, the front-side and rear-side contact regions of the first, second and third types can be electrically contacted and operated exclusively from the direction of the front side. This makes it easier to electrically actuate the excitation element.The at least one metallization can be arranged on an outer side surface and also on an inner side surface of the excitation element, for example in the case that the excitation element is ring-shaped.In an analogous manner, the excitation element can be electrically contacted exclusively on the rear side. In this case, the side-surface metallization connects the front-side contact regions of the first type, of the second type, of the third type to rear-side contact regions of the fourth type, of the fifth type and of the sixth type in a correspondingly analogous manner.In a further preferred embodiment, the optical arrangement comprises a flexible film between the radiation-transmissive pane and the excitation element. The flexible film preferably has electrical line regions which can be controlled independently of one another and are connected to the excitation element in an electrically conductive manner. The flexible film is formed with polyimide, for example. The lead portions include, for example, a metal or a metal alloy such as copper.In particular, the flexible film forms a mechanical connection between a housing of the optical arrangement and the pane and / or the excitation element. The disk is arranged in particular together with the excitation element in an opening of a housing. The housing can be arranged, for example, on the camera or the camera lens which is to be covered by the optical arrangement. For this purpose, the housing has, for example, a thread on a side facing away from the disk.A mechanical connection between the disk and the excitation element and the housing is preferably formed by means of the flexible film. For example, the flexible film forms the only mechanical connection between the disc / excitation element and the housing. The flexible film can be clamped or glued, for example, between two elements, for example a thread and a cover of the housing. The flexible film carries in particular the pane and the excitation element. The disk and the excitation element are thus arranged flexibly in the housing. Damping of the oscillating disc due to a suspension is thus reduced. This means that the pane has a relatively high freedom of movement. At the same time, the excitation element can be electrically controlled and operated via the line regions of the flexible film.The flexible film is, for example, of annular configuration. An outer diameter is preferably greater than an outer diameter of the excitation element and a diameter of the disk. Advantageously, the flexible film can be connected to the housing. The outer diameter of the film is, for example, 23 mm in the case where the diameter of the disk is 21 mm.If the excitation element has front-side and / or rear-side contact regions, at least some of these contact regions are preferably electrically conductively connected to the line regions of the flexible film. An electrical connection can also be achieved partially by means of side-surface metallizations of the excitation element. Preferably, the front-side and rear-side contact regions can be electrically contacted from the direction of the front or rear side by means of the flexible film and the line regions thereof. Between the line regions of the flexible film and the front-side or rear-side contact regions there is preferably a one-to-one assignment. This means in particular that each front-side or rear-side contact region is assigned exactly one line region of the flexible film and vice versa.In a preferred development, the optical arrangement has a further flexible film on a side of the excitation element facing away from the pane. The arrangement thus preferably has two flexible films, between which the excitation element is arranged. The further flexible film preferably has electrical line regions which can be controlled independently of one another and are electrically conductively connected to the excitation element. The further flexible film is preferably formed with the same materials as the flexible film and has a similar or the same geometric shape and dimensions.A further mechanical connection can be formed between the housing and the excitation element or the excitation element and the pane via the further flexible film. In this way, in particular a mechanical stability of the pane in the housing can be increased and at the same time a relatively high freedom of movement of the pane can be ensured.The further film is preferably provided if the excitation element has front-side and rear-side contact regions. In this case, in particular the flexible film is configured for electrically contacting the front-side contact regions and the further flexible film is configured for electrically contacting the rear-side contact regions. Between the conducting areas of the flexible film and the front contact areas there is preferably a one-to-one assignment. This means in particular that each front-side contact region is assigned exactly one line region of the flexible film and vice versa. In an analogous manner, there can likewise be a one-to-one association between the rear-side contact regions and the further line regions of the further flexible film.If the side face of the excitation element has a metallization, at least one of the conduction regions of the flexible film or of the further flexible film is preferably electrically conductively connected to the side-face metallization.Preferably, the flexible film and / or the further flexible film has a web. The web extends in a direction transverse to a main extension direction of the flexible film. The web preferably has connection regions via which the line regions of the flexible film and / or the further line regions of the further flexible film can be contacted externally. That is to say that the line regions of the flexible film can be electrically actuated via the connection regions of the web and consequently the front-side and / or rear-side contact regions of the excitation element. The web is thus designed for external energization or actuation of the excitation element.In a further preferred embodiment, the arrangement has a housing and a cover element. The housing has an opening in which the radiation-transmissive pane is arranged. On a second main side of the pane, which is opposite the first main side, a cover element is arranged. The cover element is arranged in particular in such a way that the opening is hermetically sealed by the cover element together with the pane. This means in particular that the cover element engages from the pane onto the housing. A possible gap between the pane and the housing is thus covered by the cover element in view of the second main side.The cover element is, for example, a film and is preferably formed with a plastic such as polyimide. A diameter of the cover element is preferably greater than a diameter of the disk. For example, the diameter of the disk is 21 mm and the diameter of the cover member is 30 mm. A gap between the disc and the housing may be 2 mm. The cover element can be annular, wherein viewed from the second main side, it can be seen in an opening of the cover element. The cover element is preferably fastened to the pane and the housing by means of adhesive bonding.The cover element advantageously prevents moisture, dirt or other contaminants from entering the interior of the housing. Furthermore, a mechanical stability of the pane in the housing can be increased by the cover element. By forming the cover element as a film, a relatively high freedom of movement of the pane in the housing can be achieved at the same time.Furthermore, a method for operating an optical arrangement is specified. The method can be used in particular to operate an optical arrangement described here. That is, all features disclosed for the optical arrangement are also disclosed for the method and vice versa.The method for operating the optical arrangement comprises exciting at least one rotationally symmetrical bending mode in the central region of the pane by means of the excitation element, so that the pane is excited at least to a first bending vibration, wherein the first bending vibration is a standing wave, and the first bending vibration has nodes in the edge region of the pane. This means in particular that the first bending oscillation has maxima and minima in the center or in the center of the pane. A deformation of the pane decreases in the direction of the edge region of the pane and decreases to zero or substantially to zero at the edge of the pane. That is, by means of the first bending vibration, the disc is deformed and vibrates only in the central region. A deformation or oscillation in the edge region is not excited or achieved by the rotationally symmetrical bending mode or the first bending oscillation. The first flexural oscillation comprises, in particular, a wave train.The method for operating the optical arrangement further comprises exciting at least one non-rotationally symmetrical bending mode at least in the edge region of the pane by means of the excitation element, so that the pane is excited at least in the edge region to a second bending vibration, wherein the second bending vibration is a moving wave and the second bending vibration has migrating nodes in the edge region.For example, at least three or exactly three bending modes are excited in the edge region with the excitation element. Local maxima and local minima of the second bending oscillation resulting from the superposition of the bending modes are preferably present in the edge region and travel in the edge region along a contour of the pane. That is, on average, no region of the edge region is at rest, since the disk in the edge region is deformed in each region by the moving wave during operation.The moving shaft has in particular at least two shaft trains. For example, the moving wave can have two or three wave trains, depending on the actuation of the excitation element.The method further comprises superimposing the rotationally symmetric bending modes and the non-rotationally symmetric bending modes to form a total bending vibration of the pane. Thus, the total flexural vibration of the pane is composed of the first flexural vibration and the second flexural vibration in a nontrivial manner.Superposition of the rotationally symmetrical bending modes and non-rotationally symmetrical bending modes has the effect, in particular, that during operation of the optical arrangement the disk is on average not at rest in any region. That is, in particular, during operation, the disc is deformed and moved in each region or point on the second main side. This advantageously allows a cleaning effect of the pane to be achieved in all regions and points of the pane.Further advantages and advantageous embodiments and developments of the optical arrangement and of the method for operating the optical arrangement result from the exemplary embodiments illustrated below in conjunction with schematic drawings. Identical, similar and identically acting elements are provided with the same reference numerals in the figures. The figures and the relative sizes of the elements shown in the figures with respect to one another are not to be regarded as being fundamentally true to scale. Rather, individual elements may be represented with exaggerated size for better representability and / or for better understanding. FIGS. 1 to 4 show an optical arrangement according to a first exemplary embodiment described here in different views, FIG. 5 is a perspective view of a flexible film for an optical assembly described herein, FIG. 6 shows a perspective sectional view of an optical arrangement described here according to a second exemplary embodiment, FIGS. 7 to 17 show different exemplary embodiments for contact regions of an excitation element for an optical arrangement described here, FIGS. 18A to 21D show various exemplary bending oscillations which can be excited during operation of a pane of an optical arrangement described here.FIGS. 1 and 2 show an optical arrangement 1 described here according to a first exemplary embodiment in a sectional view and in a perspective sectional view, respectively. The sectional plane runs perpendicular to a main extension plane of a pane 2 of the optical arrangement 1.The optical arrangement 1 comprises a radiation-transmissive pane 2 and an excitation element 3 on a first main side 21 of the pane 2. Preferably, the pane 2 is radiation-transmissive for radiation which is to be captured by the camera. The optical arrangement 1 is in particular part of a lens cleaning system for the camera lens.The excitation element 3 is a piezoceramic excitation element and is formed with a piezoceramic. By applying a voltage to the excitation element 3, this expansion or contraction can be achieved. A deformation of the pane 2 can thus be induced by means of the excitation element 3.The disk 2 is circular and the excitation element 3 is ring-shaped. An outer diameter 31 of the excitation element 3 corresponds substantially to a diameter 23 of the disk 2. the outer diameter 31 is, for example, 21 mm and the diameter 23 of the disk 2 is, for example, likewise 21 mm. A thickness 24 of the pane 2 is, for example, 1.5 mm and a thickness 34 of the excitation element 3 is, for example, likewise 1.5 mm. The thicknesses 24, 34 are measured perpendicular to the first main side 21.The pane 2 has a central region 4 and a circumferential edge region 5. The edge region 5 preferably completely encloses the central region 4 in lateral directions. Lateral directions are the following directions parallel to the first main side 21.The excitation element 3 is configured to excite a rotationally symmetrical bending mode in the central region 4. The disk 2 is deformed in the central region by the rotationally symmetrical bending mode, so that a first bending vibration of the disk 2 is excited in the central region 4. The first bending vibration is rotationally symmetrical. That is to say that during operation of the optical arrangement 1, the first bending oscillation in the central region 4, preferably in the center of the pane 2, alternately has local maxima and local minima, which drop in the direction of the edge region 4. In the edge region 4, the first bending oscillation exhibits essentially no amplitude. This means that by exciting the rotationally symmetrical bending mode, no deformation or movement of the pane 2 in the edge region 5 can be achieved.Furthermore, the excitation element 3 is configured to excite non-rotationally symmetrical bending modes in the edge region 5. In particular, three non-rotationally symmetrical bending modes are excited in the edge region 5 during normal operation. A superposition of the three non-rotationally symmetrical bending modes results in a running wave in the edge region 5. a second bending oscillation, which is formed by the running wave, has local maxima and local minima in the edge region, which during operation of the optical arrangement 1 move in the edge region 5 along a contour of the pane 2. The local maxima and local minima of the second bending oscillations decrease linearly in the direction of the central region 4.In the intended operation, the first and second bending oscillations are also superimposed, resulting in a complex overall bending oscillation. The superposition of the first and second flexural oscillations can ensure that the entire pane 2 is set in oscillation both in the central region 4 and in the edge region 5.For example, the optical assembly 1 is used as a cover or guard for a camera or camera lens. In this case, there is fundamentally the desire to protect the camera or camera lens from dirt or water and, if appropriate, to remove dirt and water from the camera and camera lens, that is to say to clean the pane 2 of the optical arrangement 1. This cleaning is achieved by ultrasonic cleaning. In this case, the pane 2 is set in vibration by means of the excitation element 3, so that dirt or water is removed from the pane 2. The optical arrangement 1 described here can serve, for example, as covers for optical sensors, for example in the automobile sector, or for monitoring cameras, in particular in the exterior sector.The optical arrangement 1 further comprises a flexible film 10. The flexible film 10 has conduction regions which are electrically conductively connected to the excitation element 3. The flexible film 10 is arranged between the disc 2 and the excitation element 3. The flexible film 10 has a web 12 which comprises connection points. The connection points are designed for electrical contacting. The connection points are electrically conductively connected to the line regions of the flexible film 10. The excitation element 3 can thus be electrically contacted via the web.The composite of the pane 2, the excitation element 3 and the flexible film 10 is arranged in a housing 100.In particular, this composite is arranged in an opening 103 of the housing 100. A mechanical connection between the housing 100 and the pane 2 and the excitation element 3 is formed in particular exclusively by the flexible film 10 and a cover element 13 designed as a film.The housing 100 has, for example, a first part formed as a thread 101 and a second part formed as a cover 102. The flexible film 10 can be clamped or bonded between the thread 101 and the cover 102. For example, the cover 102 is screwed or bonded to the thread 101.The cover element 13 is arranged on a second main side 22 of the pane 2, which is opposite the first main side 21. The cover element 13 is formed as a film and is formed with polyimide. The cover element 13, together with the pane 2, hermetically seals the opening 103 of the housing 100. For this purpose, the cover element 13 engages from the pane 2 onto the housing 100. A gap between the case 100 and the disk 2 is thus hermetically sealed.The cover element 13 is of annular configuration and has an outer diameter of 30 mm. With regard to the second main side 22, the pane 2, in particular the central region 5 of the pane 2, can be seen in an opening of the cover element 13.Because a mechanical connection between the pane 2 and the housing 100 is formed only by the foils 10, 13, the pane 2 has a relatively high freedom of movement. That is, attenuation of the total bending vibration of the glass 2 is relatively small.FIGS. 3 and 4 show the optical arrangement 1 according to the first exemplary embodiment in a perspective view. In FIG. 3, a front side of the optical arrangement 1 is shown with a view to the second main side 22 of the disk 2, and in FIG. 4, the optical arrangement 1 is shown with a view to the first main side 21 of the disk 2. As can be seen in FIGS. 3 and 4, the housing 100 has a thread 101 on a side facing away from the disk 2. The thread 101 can be used to mount the optical arrangement on a camera or a camera lens.FIG. 5 shows a flexible film 10 as used in the first exemplary embodiment of the optical arrangement 1 according to FIGS. 1 to 4. The flexible film 10 is designed as a ring and an outer diameter of the flexible film 10 is greater than the diameter 24 of the disk 2. the film 10 can thus serve in the housing 100 as a mechanical suspension for the disk 2 and the excitation element 3. The outer diameter of the film 10 is in particular 23 mm or more. The flexible film is formed with polyimide. The lead portions are formed with copper.The flexible film 10 has a web 12 which extends transversely, in particular perpendicularly, to a main direction of extension of the flexible film 10. The web 12 has the connection regions with which the line regions and ultimately the excitation element 3 can be electrically contacted. Due to the arrangement of the web perpendicular to the main plane of extension of the flexible film 10, these connection points are advantageously particularly easily accessible externally, as can also be seen in FIG. 4.FIG. 6 shows an optical arrangement 1 according to a second exemplary embodiment in a perspective sectional view. The optical arrangement 1 according to FIG. 6 differs in particular from the optical arrangement 1 according to the first exemplary embodiment in that the optical arrangement 1 according to the second exemplary embodiment has a further flexible film 11.The further flexible film 11 is arranged in particular on a rear side 32 of the excitation element 3 facing away from the first main side 21. The further flexible film 11, like the flexible film 10, has line regions and a web. In particular, the further flexible film 11 corresponds to the flexible film 10 in almost all features, with the exception of the arrangement on the excitation element 3.In particular, the front side 31 of the excitation element 3 can be electrically conductively contacted by means of the flexible film 10 and, for example, the rear side 32 of the excitation element 3 can be electrically conductively contacted by means of the further flexible film 11. By means of the further flexible film 11, in particular a mechanical connection to the housing 100 is likewise formed.FIG. 7 shows a perspective view of the front side 31 of an excitation element 3 for an optical arrangement 1 described here. The front-side contact regions 6 are for example sputtered and comprise copper.In the exemplary embodiment of FIG. 7, the excitation element 3 has two front-side contact regions of the first type 61, two front-side contact regions of the second type 62 and two front-side contact regions of the third type 63. In the clockwise direction, viewed on the front side 31, a contact region of the second type 62 follows a contact region of the first type 61, and a contact region of the second type 62 is further followed by a contact region of the third type 63, which is again followed by a contact region of the first type 61.During normal operation, a first voltage is applied to the first type contact regions 61, a second voltage is applied to the second type contact regions 62, and a third voltage is applied to the third type contact regions 63. The applied voltages can deform the excitation element 3, which comprises a piezoceramic. This deformation is transmitted to the disc 2. With suitable control of the excitation element 3, the disc can thus be set in oscillation. This means that three non-rotationally symmetrical bending modes can be excited in the edge region 5 in the pane 2 by means of the first, second and third stresses. Superposition of these bending modes produces the second bending vibration.In the exemplary embodiment of FIG. 7, the second bending oscillation has two wave trains. This means that the bending oscillation has two maxima and two minima which run along a contour of the pane 2 (compare FIG. 19 ).The first, second and third voltages each have the same amplitude and frequency. In particular, the first, second and third voltages are each a harmonic alternating voltage. The amplitude is, for example, 10 V and the frequency is, for example, 16.78 kHz. The second voltage is phase shifted by 120° from the first voltage. The third voltage is phase shifted by 240° from the first voltage.Furthermore, in operation, a fourth voltage is applied to the contact regions 6, which is applied jointly to all the contact regions 6. The fourth voltage is preferably also a harmonic alternating voltage and has a frequency of 10 V and a frequency of 34.5 kHz. By means of the fourth stress, the rotationally symmetrical bending mode and consequently the first bending vibration in the central region 4 of the pane 2 can be excited. By applying or suitably superimposing the first, second, third and fourth voltages simultaneously, the overall bending oscillation can thus be generated.FIG. 8 shows an alternative embodiment of the excitation element 3, in which three front-side contact regions 6 of the first type 61, the second type 62 and the third type 63 are arranged in each case on the front side 31. The front-side contact regions of the first type 61, the second type 62 and the third type 63 follow one another in the sequence described in connection with FIG. 7.A first voltage can be applied to the first type contact regions 61 in an analogous manner, as described in connection with FIG. 7, a second voltage can be applied to the second type contact regions 62, a third voltage can be applied to the third type contact regions 63 and then all front side contact regions 6 a fourth voltage. In contrast to the embodiment of FIG. 7, a second bending oscillation can be excited with the contact regions 6 according to FIG. 8, which second bending oscillation has three wave trains. This means that the running wave in the edge region 5 has three maxima and three minima (compare FIG. 20 ).FIG. 9 shows a perspective view of the rear side 32 of the excitation element 3 according to FIG. 7 or 8. That is, the rear side 32 is preferably free of an electrical potential. The ground contact 8 forms in particular the complete rear side of the excitation element 3.In contrast to FIGS. 7 to 9, it is possible for the front side 31 to have the ground contact 8 and for the rear side 32 to be provided with rear-side contact regions 7, in particular rear-side contact regions of the first type 71, second type 72 and third type 73. The rear-side contact regions 7 are arranged on the rear side 32 in a correspondingly analogous manner to the front-side contact regions 6. In this case, electrical contacting is correspondingly analogous to the electrical contacting of the front-side contact regions 6, as described in connection with FIGS. 6 and 7.FIGS. 10 and 11 show the excitation element 3 according to FIGS. 7 and 9 in a perspective view, wherein the excitation element 3 of FIG. 10 additionally has a metallization 9 on a side surface 35. The side surface 35 connects the front side 31 to the rear side 32.The ground contact 8 can be drawn from the rear side 32 onto the front side 31 via the metallization 9. This means that the metallization 9 forms a changeover contact for the ground contact 8. Thus, the excitation element 3, as shown for example in FIG. 1, can be electrically contacted via the flexible film 10.It is also possible for the ground contact 8 to be arranged on the front side 31 and for the rear side 32 to have rear-side contact regions 7, wherein the ground contact 8 of the front side 31 is drawn onto the rear side 32 via the metallization 9. In this case, electrical contacting of the excitation element 3 can take place exclusively via the rear side 32.It is likewise possible for the excitation element 3 to have front-side contact regions 6 and rear-side contact regions 7. Metallizations 9 on the side surface 35 can be used to make contact with the front-side contact elements 6 on the rear side 32 or to make contact with the rear-side contact elements 7 on the front side 31. In this case, it is possible that electrical contacting of the front-side and rear-side contact regions 6, 7 can take place exclusively from the direction of the front side 31 or the rear side 32.FIGS. 12 and 13 illustrate an excitation element 3 in which front-side contact regions 6 of the first type 61, the second type 62 and the third type 63 are arranged on the front side 31. Rear-side contact regions 7 of the first type 71, second type 72 and third type 73 are arranged on the rear side of the excitation element 3. The arrangement of the contact regions of the first type 61, 71, second type 62, 72 and third type 63, 73 is correspondingly as described in FIG. 7.In a projection onto a common plane parallel to the front side 31, that is to say for example a plane in which the front side 31 lies, the front-side contact regions 6 overlap with the rear-side contact regions 7. That is, in the projection onto the common plane, the front contact regions 6 completely cover the rear contact regions 7 and vice versa. Each front-side contact region of the first type 61 overlaps a rear-side contact region of the second type 62, each front-side contact region of the second type 62 overlaps a rear-side contact region of the third type 73, and each front-side contact region of the third type 63 overlaps a rear-side contact region of the first type 71.Electrical contacting of the contact regions 6, 7 is effected in particular without ground. This means that the excitation element 3 does not have a ground contact 8. In particular, a modified first voltage, a modified second voltage, a modified third voltage and the fourth voltage can be applied to the contact regions 6, 7, as explained above. The modified first voltage corresponds to the first voltage except for in amplitude. The modified first voltage has an amplitude that is a factor less than the first voltage. The same applies analogously to the modified second and the modified third voltage.FIGS. 14 and 15 show an alternative arrangement of the front-side contact regions 6 and rear-side contact regions 7. the front-side contact regions 6 are arranged correspondingly analogously to the front-side contact regions 6 according to FIG. 8. In a projection onto the front side 31, the front-side contact regions 6 and the rear-side contact regions 7 overlap in particular completely. Each front-side contact region of the first type 61 overlaps a rear-side contact region of the second type 62, each front-side contact region of the second type 62 overlaps a rear-side contact region of the third type 73, and each front-side contact region of the third type 63 overlaps a rear-side contact region of the first type 71.As in the arrangement of the contact regions 6, 7 according to FIGS. 12 and 13, the modified first voltage, the modified second voltage and the modified third voltage and the fourth voltage can be applied to the contact regions 6, 7 of FIGS. 14 and 15 in order to generate the overall bending vibration in the pane 2.FIG. 16 shows a combined view of a front side 31 and a rear side 32 of an excitation element 3. On the front side 31, the excitation element 3 comprises a front-side contact region of the first type 61, a front-side contact region of the second type 62 and a front-side contact region of the third type 63. On the rear side 32, represented by the inner ring in FIG. 16, the excitation element comprises a rear-side contact region of the first type 71, a rear-side contact region of the second type 72 and a rear-side contact region of the third type 73.The front-side contact regions 6 and the rear-side contact regions 7 are arranged offset with respect to one another in a projection into a common plane of, for example, the front side 31. This means in particular that in the projection each front contact region 6 overlaps with at least two rear contact regions 7 and vice versa. In comparison with FIGS. 12 and 13, the proportion of the front-side contact regions 6 and rear-side contact regions 7 can thus be reduced and, at the same time, the first and second flexural oscillations can be excited by applying the first, second, third and fourth voltages. The second flexural vibration comprises two wave trains.FIG. 17 shows an embodiment of an excitation element 3 described here in a view of the front side 31 and rear side 32, in which front-side contact regions 6 and rear-side contact regions 7 are arranged offset with respect to one another. The exemplary embodiment of FIG. 17 differs from the exemplary embodiment of FIG. 16 in particular in that three wave trains can be excited in the second bending vibration with the excitation element 3 of FIG. 17. Therefore, FIGS. 16 and 17 differ in the front-side contact regions 6 and rear-side contact regions 7.In the embodiments of FIGS. 16 and 17, in the projection onto the common plane, each front-side first-type contact region 61 overlaps with a rear-side second-type contact region 72 and a rear-side third-type contact region 73. Further, each front-side second-type contact region 62 overlaps with a rear-side first-type contact region 71 and a rear-side third-type contact region 73.This arrangement of the front-side and rear-side contact regions 6, 7 fulfills a predefined polarity direction 60, illustrated by the arrows 60 in FIGS. 16 and 17. the polarity direction 60 points from a first-type contact region 61, 71 to a third-type contact region 63, 73, from a second-type contact region 62, 72 to a first-type contact region 61, 71 and from a first-type contact region 61, 71 to a third-type contact region 63, 73 to a second-type contact region 62, 72.The polarity direction 60 is predefined by the sequence of the contact regions of the first type, of the second type and of the third type. The polarity direction 60 ensures, in particular, that during operation a phase offset of the first voltage with respect to the second and third voltages is fulfilled in such a way that superposition of the three bending modes generates a standing wave. This is achieved in FIGS. 16 and 17 in particular in that, viewed in the counterclockwise direction 60, a contact region of the first type 61, 71 follows a contact region of the third type 73, 63, a contact region of the second type 62, 72 follows a contact region of the third type 73, 63, and a contact region of the second type 62, 72 follows a contact region of the first type 71, 61. Thus, in the polarization direction 60, the sequence of the first, second and third contact regions 61, 71, 62, 72, 63, 73 in FIGS. 16 and 17 is corresponding to FIGS. 14 and 15.FIGS. 18A and 18B illustrate a first bending oscillation, as can occur during operation of the optical arrangement 1. FIG. 18A illustrates a deformation 80 of the disc 2 at a first time and FIG. 18B illustrates the deformation 80 at a later time during a period of the first bending vibration.In the case of the first bending vibration, the pane 2 deforms in the central region 5. In the exemplary embodiment of FIG. 18, a maximum deformation is, for example, 2.3·10 -6 m. The deformation decreases in the direction of the edge region and amounts to 0 m or substantially 0 m in the edge region. During operation of the optical arrangement 1, the disc 2 oscillates, so that the deformation 80 becomes maximum in the central region and decreases to zero over time before it again assumes its maximum value.FIGS. 19A and 19B illustrate the second bending vibration, wherein a running wave of the second bending vibration has two wave trains. The second bending oscillation is a superposition of three phase-shifted bending modes, so that the second bending oscillation is a running wave and maxima and minima of the second bending oscillation travel along a contour of the pane 2. FIG. 19A shows a deformation 80 at a first point in time and FIG. 19B shows the deformation 80 at a later second point in time during a period of the second bending vibration. As can be seen from the comparison, the maxima and minima have moved along the contour of the pane 2. A maximum deformation 80 of the pane 2 is approximately 8.3·10 -7 m.FIG. 20 illustrates a second bending vibration of the pane 2. FIG. 20 shows a deformation 80 of the pane 2 at two different points in time, FIG. 20A at a first point in time, FIG. 20B at a later second point in time during a period of the second bending vibration. In contrast to the second flexural oscillation of FIG. 19, the second flexural oscillation of FIG. 20 has three wave trains. Like FIG. 19, the second bending oscillation of FIG. 20 is a running wave, wherein the local maxima and minima travel along the contour of the pane 2. A maximum deformation 80 is about 3.5·10 -7 m.FIG. 21 shows a total bending vibration resulting from superposition of the first and second bending vibrations of the pane 2, FIG. 21A showing a deformation 80 of the pane 2 at a first point in time, FIG. 21B showing the deformation 80 at a later second point in time, FIG. 21C showing the deformation 80 at a further later point in time and FIG. 21D showing the deformation 80 at a further later point in time during a period of the total bending vibration.As can be seen from FIGS. 21A to 21D, local maxima and minima form both in the edge region and in the central region of the pane 2. A maximum deformation 80 of the pane 2 is about 4.5·10-7 m. As can be seen in FIG. 21, superposition of the first and second bending oscillations causes essentially all regions or all points of the pane 2 to flex or oscillate or vibrate or move during operation of the optical arrangement 1.Thus, by a combination of the first and second bending oscillations, i.e. a superposition of the rotationally symmetrical bending modes and non-rotationally symmetrical bending modes, it is possible to excite a total bending oscillation, by means of which the pane 2 is set in oscillation substantially in all regions during operation of the optical arrangement 1. The optical arrangement 1 can thus be cleaned by ultrasonic cleaning of dirt, water residues or rain by means of the overall bending vibration. A cleaning effect is advantageously not limited to the central region, but can be achieved in all regions of the pane 2.Reference numerals denote reference numerals1 Optical arrangement 2 Radiation-transmissive disc 3 Piezoelectric excitation element 4 Central region 5 Edge region 6 Front-side contact regions 7 Rear-side contact regions 8 Ground contact 9 Metallization 10 Flexible film 11 Further flexible film 12 Web 13 Covering film 21 First main side 22 Second main side 23 Diameter 24 Thickness 31 Front side 32 Rear side 33 Outer diameter of the excitation element 34 Thickness 35 Side surface 60 Polarity direction 61 Front-side contact of first type 62 Front-side contact of second type 63 Front-side contact of third type 71 Rear-side contact of first type 72 Rear-side contact of second type 73 Rear-side contact of third type 80 Deformation 100 Housing 101 Thread 102 CoverReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedU.S. Pat. No. 10,682,675 B2

[0004]

Claims

Optical arrangement (1) comprising a radiation-transmissive disc (2) and a piezoelectric excitation element (3), wherein - the excitation element (3) is arranged on a first main side (21) of the disc (2), - the radiation-transmissive disc (2) has a central region (4) and an edge region (5) encircling the central region, - the excitation element (3) is configured to excite at least one rotationally symmetrical bending mode in the central region (4) of the radiation-transmissive disc (2), and - the excitation element (3) is configured to excite at least one non-rotationally symmetrical bending mode in the edge region (5) of the radiation-transmissive disc (2), said bending mode generating a moving wave in the edge region (5).Arrangement (1) according to claim 1, wherein - radiation-transmissive disc (2) is circular, - the excitation element (3) is annular, - an outer diameter (33) of the annular excitation element (3) substantially corresponds to a diameter (23) of the circular disc (2), and - in view of the first main side (21), the edge region (5) of the disc (2) is at least partially covered by the excitation element (3).Arrangement (1) according to Claim 1 or 2, wherein - the excitation element (3) has a plurality of front-side contact regions (6) on a front side (31) facing the first main side (21) of the pane (2), and - the front-side contact regions (6) can be electrically contacted independently of one another.Arrangement (1) according to one of the preceding claims, wherein - the excitation element (3) has a plurality of rear-side contact regions (7) on a rear side (32) facing away from the first main side (21), and - the rear-side contact regions (7) can be electrically contacted independently of one another.Arrangement (1) according to claims 3 and 4, wherein - the front-side contact regions (6) and the rear-side contact regions (7) are electrically contactable independently of one another, and - in a projection into a common plane parallel to the front side (31), the front-side contact regions (6) are arranged offset from the rear-side contact regions (7).Arrangement (1) according to either of Claims 3 and 4, wherein a ground contact (8) is arranged on a side of the excitation element (3) which is opposite the contact regions (6, 7).Arrangement (1) according to one of claims 3 to 6, wherein a distance between two adjacent front side contact regions (6) and / or two adjacent rear side contact regions (7) is between 0.2 mm and 1 mm inclusive.Arrangement (1) according to one of Claims 3 to 7, wherein - the excitation element (3) has a thickness (34) of between 0.2 mm and 0.7 mm inclusive, and - a distance between two adjacent front-side contact regions (6) and / or two adjacent rear-side contact regions (7) is between one third and one half of the thickness (34) of the excitation element (3).Arrangement (1) according to one of the preceding claims, wherein - the excitation element (3) has at least one front-side contact region (6) and at least one rear-side contact region (7), and - the excitation element (3) has at least one metallization (9) on a side surface (35), said metallization electrically conductively connecting at least one front-side contact region (6) and at least one rear-side contact region (7) to one another.Arrangement (1) according to one of the preceding claims, wherein a flexible film (10) is arranged between the radiation-transmissive pane (2) and the excitation element (3), the flexible film (10) having electrical conduction regions which can be controlled independently of one another and are electrically conductively connected to the excitation element (3).Arrangement (1) according to claim 10, further comprising a housing (100), wherein a mechanical connection between the housing (100) and the pane (2) and / or the excitation element (3) is formed by the flexible film (10).Arrangement (1) according to claim 10 or 11 when referring back to claim 3 or 4, wherein the conducting areas of the flexible film (10) are electrically conductively connected to the front-side contact areas (6) or rear-side contact areas (7).Arrangement (1) according to one of Claims 10 to 12, further comprising a further flexible film (11) on a side of the excitation element (3) facing away from the pane (2), wherein the further flexible film (11) has further electrical conduction regions which can be controlled independently of one another and are electrically conductively connected to the excitation element (3).Arrangement (1) according to claim 13 when referring back to claim 11, wherein the further flexible film (11) forms a further mechanical connection between the housing (100) and the pane (2) and / or the excitation element (3).Arrangement (1) according to claim 13 or 14 when referring back to claim 3 and 4 or when referring back to claim 5, wherein the conducting areas of the flexible film (10) between the pane (2) and the excitation element (3) are electrically conductively connected to the front-side contact areas (6), and the further conducting areas of the further flexible film (11) are electrically conductively connected to the rear-side contact areas (7).Arrangement (1) according to one of Claims 10 to 15 when appended to Claim 9, wherein at least one of the conduction regions of the flexible film (10) is electrically conductively connected to the at least one metallization (9) of the excitation element (3).Arrangement (1) according to one of Claims 10 to 16, wherein - the flexible film (10) has a web (12), - the web (12) extends in a direction transverse to a main direction of extent of the flexible film (10), and - the web (12) has connection regions via which the line regions of the flexible film (10) can be contacted externally.Arrangement (1) according to one of the preceding claims, further comprising a housing (100) and a cover element (13), wherein - the housing (100) has an opening (103) in which the radiation-transmissive pane (2) is arranged, - the cover element (13) is arranged on a second main side (22) of the pane (2) which is opposite the first main side (21), and - the opening (103) is hermetically sealed by the cover element (13) together with the writing (2).Method for operating an optical arrangement (1) according to one of the preceding claims, comprising: - excitation of at least one rotationally symmetrical bending mode in the central region (4) of the pane (2) by means of the excitation element (3) such that the pane is excited at least to a first bending vibration, wherein the first bending vibration is a standing wave and the first bending vibration has nodes in the edge region (5), - excitation of at least one non-rotationally symmetrical bending mode at least in the edge region (5) of the pane (2) by means of the excitation element (3) such that the pane (2) excites to a second bending vibration at least in the edge region (5), wherein the second bending vibration is a running wave and the second bending vibration has migrating nodes in the edge region, - superposition of the rotationally symmetrical bending mode and the non-rotationally symmetrical bending mode to form a total bending vibration of the pane (2).Method according to claim 19, wherein at least three bending modes are excited in the edge region (5) by means of the excitation element (3) and the at least three bending modes are superimposed to form the second bending oscillation, and - the second bending oscillation has at least two wave trains.

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