Optical arrangement and method for operating an optical arrangement

Abstract

The optical arrangement (1) comprises a radiation-permeable disc (2) and a piezoelectric excitation element (3). The excitation element (3) is arranged on a first main side (21) of the disc (2). The radiation-permeable disc (2) has a central region (4) and a border region (5) surrounding 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-permeable disc (2). The excitation element (3) is further configured to excite at least one non-rotationally-symmetrical bending mode in the border region (5) of the radiation-permeable disc (2), said bending mode generating a travelling wave in the border region (5).

Description

[0001] Description

[0002] Optical arrangement and method for operating an optical

[0003] arrangement

[0004] The invention relates to an optical arrangement and a method for operating such an optical arrangement.

[0005] In camera applications, particularly outdoor applications, there is typically a requirement for them to deliver perfect images even in rain or after they have become dirty. This is particularly the case when the camera is used in the automotive sector. If, for example, the camera is part of a sensor or a lidar system for an automobile, there is a need for a camera that functions well even in bad weather conditions in order to increase or ensure the vehicle’s autonomy. Outdoors, the camera could be a surveillance camera, for example. There is therefore a fundamental need to be able to clean the camera in order to remove rain or dirt from a cover or a lens of the camera.

[0006] Conventional cleaning systems are based on the cleaning effect of water jets and / or mechanical wiping systems. Alternatively, the camera can be cleaned with ultrasound. This process is also known as “ultrasonic lens cleaning”. Typically, a camera cover is set into vibration in order to atomise the water on it or to create a thin vapor film between the surface of the cover and the water so that the water can be easily removed. Typically, the cover is only set into vibration in a central region, while in an edge region the cover remains more or less at rest. 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 area is typically free of oscillations or vibrations, this leads to impairments in the recording quality of the camera and, for example, in the case of autonomous driving, the vehicle's autonomy may be insufficient.

[0007] The document US 10,682,675 B2 describes a system for lens cleaning using ultrasound.

[0008] One problem to be solved is to provide an improved optical arrangement that can function as a cover for a camera or a camera lens and enables improved cleaning in the edge region. Another problem to be solved is to specify a method for operating such an optical arrangement.

[0009] These objects are achieved by a subject matter having the features of independent patent claim 1 and by a method having the features of patent claim 19. Advantageous further developments and refinements are the subject matter of the respective dependent patent claims.

[0010] An optical arrangement is proposed which has a radiation-permeable disk and a piezoelectric excitation element. The excitation element is arranged on a first main side of the disk. The radiation-permeable disk has a central region and an edge region surrounding the central region. The excitation element is designed to excite at least one rotationally symmetric bending mode in the central region of the radiation-permeable disk. The excitation element is further designed to excite at least one non-rotationally symmetric bending mode in the edge region of the radiation-permeable disk, which bending mode generates a rotating wave in the edge region.

[0011] The radiation-permeable pane is, for example, a cover for a camera or a camera lens. This means that the pane is arranged in front of the camera or 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.

[0012] “Radiation-permeable” here and below means that the pane is permeable to incoming electromagnetic radiation, such as visible light. 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-permeable in a wavelength range in which, for example, a downstream camera is sensitive. If, for example, the camera is a camera for an infrared sensor, the pane is preferably radiation-permeable to electromagnetic radiation in the infrared wavelength range. The pane comprises, for example, a glass, a polymer and / or a laminated glass. The glass comprises, for example, a silicate glass, borosilicate glass, such as K9 glass (borosilicate) and / or an aluminum silicate 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 from a ceramic material such as a piezoceramic. This means that, by applying an electrical voltage, the excitation element can be spatially deformed, in particular, expanded or contracted. Thus, by applying an electrical voltage, a mechanical movement can be excited in the excitation element, which can be transferred to the disk.

[0013] If a corresponding voltage is excited during operation of the optical arrangement, a vibration, in particular a bending vibration, can be excited in the disk by means of the excitation element. The bending vibration preferably has several modes.

[0014] During operation, the disk is excited by means of the excitation element in such a way that at least one rotationally symmetric bending mode is generated in the central region of the disk. An associated deformation of the disk in the central region, which is due to the rotationally symmetric bending mode, is in particular rotationally symmetric. For example, the deformation is greatest in the center of the disk and then decreases evenly towards the edges. In particular, a deformation which is due to the rotationally symmetric bending mode is such that it is not present or essentially not present in the edge region. This means that no movement or essentially no movement of the disk is excited in the edge region by means of the rotationally symmetric bending mode. If, therefore, only the at least one rotationally symmetric bending mode were to be excited during operation, the edge region of the disk would essentially be at rest.The disadvantage of this is that it is not possible to achieve any cleaning effect in the edge area, as this requires oscillation or vibration of the pane.

[0015] Therefore, the excitation element is advantageously further configured to generate at least one non-rotationally symmetric bending mode in the edge region. These non-rotationally symmetric bending modes cause the disk in the edge region to oscillate or vibrate, thereby inducing a deformation of the disk in the edge region. In this case, several bending modes, preferably exactly three bending modes, can be superimposed, thereby generating a traveling wave in the edge region.

[0016] A "traveling wave" is understood here and in the following to be a wave which, in contrast to a standing wave, does not have fixed nodes. In the case of a traveling wave in the edge region, the nodes move along a contour of the disk. Thus, during operation of the optical arrangement, every region or essentially every region of the disk in the edge region is deformed and set into vibration, so that effective cleaning in the edge region is possible. The traveling wave results in particular from a combination of several bending modes, preferably exactly three bending modes.

[0017] The edge region preferably completely encloses the edge region in lateral directions. Lateral directions run parallel to a main extension plane of the disk. The edge region differs from the central region in particular in that no or essentially no deformation can be excited in the edge region by means of the rotationally symmetric bending mode. For example, in the edge region, the maximum amplitude of the bending vibration excited by the rotationally symmetric bending mode drops to a value of 1 / e times its maximum value.

[0018] During operation, the rotationally symmetric bending mode and the non-rotationally symmetric bending modes can be preferentially superimposed. Such superposition advantageously results in a complex movement of the disk and a corresponding deformation and bending vibration. This periodic movement or vibration can set the disk in motion or vibration essentially in all areas, enabling effective cleaning of the disk both in the edge area and in the central area.

[0019] The radiation-permeable disk is preferably circular. The excitation element is preferably annular, i.e., formed as a ring. An outer diameter of the annular excitation element can substantially correspond to a diameter of the circular disk. For example, the circular disk 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 disk is, for example, between 1 and 2 mm, for example 1.5 mm.

[0020] 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 can 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

[0021] The excitation element at least partially covers the edge region of the disc. It is possible that the edge region is completely covered by the excitation element in view of the first main side.

[0022] 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 independently of one another. The front-side contact regions can 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 sputtering. For example, the front-side contact regions comprise a metal or a metal alloy such as copper, aluminum, or gold.

[0023] During normal operation, a voltage can be applied to the front contact areas, which can deform the excitation element and induce movement or deformation in the disc. Different voltages can be applied to different front contact areas.

[0024] For example, the front-side contact elements can comprise front-side contact elements of the first type, the second type, and 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 a fixed amplitude and frequency. By applying three different voltages, in particular, several non-rotationally symmetric bending modes can be excited in the edge region. This can preferably generate the traveling wave in the edge region. In particular, each of the three voltages excites a non-rotationally symmetric bending mode in the disk. A superposition of these three bending modes advantageously results in the traveling wave in the edge region.

[0025] 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 amounts to, for example, 10 V. A first frequency of the first, second, and third voltages is, in particular, identical and amounts to, for example, approximately 17 kHz.

[0026] The first, second, and third voltages differ, in particular, only by a phase shift. A phase shift of the second voltage relative to the first voltage is, for example, 120°. A phase shift of the third voltage relative to the first voltage is, for example, 240°. The phase shift can also be selected differently, allowing, for example, the direction of the traveling wave to be specified.

[0027] Using the first amplitude and first frequency mentioned above, two wave trains can be excited in the edge region. This means that a wave generated in the edge region has two maxima and two minima which travel along the contour of the disc in the edge region. If, on the other hand, 10 V is selected as the second amplitude and approximately 39 kHz as the second frequency, this example results in three wave trains for the circulating wave. In this case, the traveling wave therefore 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 examples. In practice, these values ​​must be adjusted in particular in order to adapt the damping of the resulting bending oscillation to a load, for example, in particular the amount of water on the lens. The resonance frequency of the induced oscillation can also shift in the process.

[0028] By applying a fourth voltage to all front contact areas, the rotationally symmetric bending mode can be excited. The fourth voltage, for example, is a harmonic alternating voltage with a fixed amplitude and frequency. The amplitude is, for example, 10 V and the frequency is approximately 35 kHz. The voltage is preferably identical for all front contact areas, thus exhibiting no phase shift between the front contact areas of the first, second, or third type.

[0029] During normal operation, these voltages for the contact area of ​​the first type, the second type, and the third type can be superimposed. This results in particular in an applied voltage for the front contact area of ​​the first type that is a combination of the first and fourth voltages. For the front contact area of ​​the second type, this results in a voltage that is a combination of the second voltage and the fourth voltage, and for the front contact area of ​​the third type, this results in a voltage that is a combination of the third and the fourth voltages. It may be necessary to adapt the amplitudes and frequencies of the first, second, and third voltages, in particular in order to achieve sufficiently homogeneous acceleration of the disk during operation. For example, the first amplitude is adapted to 50 V and the second amplitude to 100 V.The first frequency can be adjusted to approximately 40 kHz and the second frequency can be adjusted to approximately 17 kHz.

[0030] The stated values ​​for the amplitude of the fourth voltage and the first / second amplitude and frequency of the fourth voltage and the first / second frequency are to be considered purely exemplary. In practice, these values ​​must be adjusted in particular to adapt the damping of the resulting bending vibration to, for example, a load, specifically the amount of water on the lens. This can also shift the resonance frequency of the induced vibration.

[0031] In a preferred development, the excitation element has a plurality of rear contact regions on a rear side facing away from the first main side of the pane. The rear contact regions can preferably be electrically controlled and / or operated independently of one another. Deformations or vibrations in the pane can be induced via the rear contact regions by applying a voltage. The rear contact regions comprise, for example, a metal or a metal alloy. In particular, the rear contact regions comprise the same materials as the front contact regions and are applied using the same methods. The rear contact regions can be present in addition to the front contact regions. However, it is also possible for the excitation element to have only rear contact regions.

[0032] If, for example, only contact areas are present on the rear side, i.e. in the case that the excitation element is free of contact areas on the front side and only has rear contact areas, the rear contact areas can preferably be contacted in a similar or identical manner to the front contact areas in the example explained above.

[0033] If, however, front and rear contact areas are present, a modified first voltage, a modified second voltage, and a modified third voltage can advantageously be applied to the front and rear contact elements. The amplitude of the modified voltages can, in particular, be selected to be a factor of 1 / V3 lower than the amplitudes of the corresponding first, second, and third voltages.

[0034] For example, the rear contact areas also comprise rear contact areas of the first type, the second type and the third type, wherein the first or the modified first voltage can be applied to the rear contacts of the first type, the second or the modified second voltage can be applied to the rear contact areas of the second type and the third or the modified third voltage can be applied to the rear contact areas of the third type.

[0035] A phase shift of the first voltage, second voltage and third voltage or the modified first voltage, the modified second voltage and the modified third voltage can be selected as described above.

[0036] Preferably, the front contact areas can be electrically contacted and / or operated independently of the rear contact areas.

[0037] For example, in a projection onto a common plane parallel to the front side, the front contact areas are offset from the rear contact areas. Alternatively, it is possible for the front contact areas and the rear contact areas to be congruent or substantially congruent with one another in this projection. The common plane may include the front side or the rear side.

[0038] If the front and rear contact areas are offset from each other, then, for example, each front contact area overlaps with at least two rear contact areas when projected into the common plane. Surprisingly, it has been found that this allows the number of contact areas to be reduced without affecting the excitation of several non-rotationally symmetric bending modes.

[0039] For example, to excite two wave trains, the excitation element has two front-side contact regions of the first type, two second type, and two third type. In addition, the excitation element can have two rear-side contact regions of the first type, two second type, and two third type. In the case of an offset arrangement, the excitation element advantageously has, for example, only one front-side contact region of the first type, two second type, and two third type, as well as one rear-side contact region of the first type, two second type, and two third type. In this case, the excitable standing wave has two wave trains in the edge region.

[0040] If, during normal operation, three wave trains are to be excited, the excitation element, in a staggered arrangement, has, for example, two contact areas of the first and third type and one contact area of ​​the second type. In comparison, in a non-staggered arrangement, the excitation element has two front-side contact areas of the first type, the second type, and the third type.

[0041] In the event that the excitation element has only front-side contact areas or rear-side contact areas, the excitation element preferably has a ground contact on a side opposite the contact areas. The ground contact can be formed by the entire corresponding front or rear side. If, for example, the excitation element has only front-side contact areas, 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 only rear-side contact areas, for example, the ground contact is preferably formed on the front side.

[0042] A distance between two adjacent front-side contact areas and / or two adjacent rear-side contact areas is, for example, between 0.2 mm and 1 mm inclusive. Alternatively or additionally, a distance between two front-side contact areas and / or two adjacent rear-side contact areas 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. Such a distance between the contact areas can prevent a coercive field strength from falling below a certain level. This can significantly reduce the risk of local overheating of the excitation element during operation.

[0043] 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 that electrically conductively connects the at least one front-side contact region and the at least one rear-side contact region. The metallization thus forms a contact connection of the excitation element. The side surface connects the front side of the excitation element to the rear side of the excitation element.

[0044] The front contact area can, for example, be a front contact area of ​​the fourth type that is electrically conductively connected to the ground contact. This allows the ground contact to be electrically conductively contacted from the front. Alternatively, it is possible for the front contact area to be electrically conductively connected to a rear contact area of ​​the first type, second type, or third type.

[0045] It is also possible for a plurality of contact regions, each of which is electrically conductively connected to a lateral-surface metallization, to be arranged on the front side. For example, the front side has front-side contact regions of the fourth type, the fifth type, and the sixth type, the front-side contact regions of the fourth type being electrically conductively connected to rear-side contact regions of the first type via a first lateral-surface metallization. Analogously, 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 lateral-surface second metallization, and the front-side contact regions of the sixth type can be electrically conductively connected to the rear contacts of the third type via a lateral-surface third metallization.This means that in this case, the front and rear contact areas of the first, second, and third type can be electrically contacted and operated exclusively from the front side. This facilitates electrical control of the excitation element.

[0046] The at least one metallization can be arranged on an outer side surface as well as an inner side surface of the excitation element, for example in the case that the excitation element is annular.

[0047] In a similar manner, the excitation element can be electrically contacted exclusively from the rear side. In this case, the lateral metallization connects the front contact areas of the first, second, and third types with the rear contact areas of the fourth, fifth, and sixth types in a correspondingly analogous manner.

[0048] In a further preferred embodiment, the optical arrangement comprises a flexible film between the radiation-permeable disk and the excitation element. The flexible film preferably has independently controllable electrical conduction regions that are electrically conductively connected to the excitation element. The flexible film is formed, for example, with polyimide. The conduction regions comprise, for example, a metal or a metal alloy such as copper.

[0049] In particular, the flexible film forms a mechanical connection between a housing of the optical arrangement and the disk 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 camera lens that 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.

[0050] A mechanical connection between the disk and the excitation element, as well as the housing, is preferably formed by the flexible film. For example, the flexible film forms the only mechanical connection between the disk / excitation element and the housing. The flexible film can, for example, be clamped or glued between two elements, such as a thread and a cover of the housing. The flexible film supports, in particular, the disk and the excitation element.

[0051] This allows the disc and excitation element to be flexibly arranged within the housing. Damping of the vibrating disc due to suspension is thus reduced. This means that the disc has a relatively high degree of freedom of movement. At the same time, the excitation element can be electrically controlled and operated via the conductive areas of the flexible foil.

[0052] The flexible foil is, for example, ring-shaped. An outer diameter is preferably larger than an outer diameter of the excitation element and a diameter of the disk. This advantageously allows the flexible foil to be connected to the housing. The outer diameter of the foil is, for example, 23 mm if the diameter of the disk is 21 mm.

[0053] If the excitation element has front and / or rear contact regions, at least some of these contact regions are preferably electrically conductively connected to the conduction regions of the flexible film. An electrical connection can also be achieved in part by means of metallization on the side of the excitation element. The front and rear contact regions can preferably be electrically contacted from the direction of the front or rear by means of the flexible film and its conduction regions. There is preferably a one-to-one assignment between the conduction regions of the flexible film and the front or rear contact regions. This means in particular that exactly one conduction region of the flexible film is assigned to each front or rear contact region 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 therefore preferably has two flexible films between which the excitation element is arranged. The further flexible film preferably has independently controllable electrical conduction regions which are electrically conductively connected to the excitation element. The further flexible film is preferably formed from the same materials as the flexible film and has a similar or identical geometric shape and dimensions.

[0054] The additional flexible film can form a further mechanical connection between the housing and the excitation element, or between the excitation element and the disk. This allows, in particular, the mechanical stability of the disk in the housing to be increased while simultaneously ensuring a relatively high degree of freedom of movement for the disk.

[0055] The further film is preferably provided if the excitation element has front and rear contact areas. In this case, in particular the flexible film is set up for electrical contacting of the front contact areas and the further flexible film is set up for electrical contacting of the rear contact areas. There is preferably a one-to-one assignment between the conducting areas of the flexible film and the front contact areas. This means, in particular, that exactly one conducting area of ​​the flexible film is assigned to each front contact area and vice versa. In an analogous manner, there can also be a one-to-one assignment between the rear contact areas and the further conducting areas of the further flexible film.

[0056] If the side surface of the excitation element has a metallization, preferably at least one of the conduction regions of the flexible film or the further flexible film is electrically conductively connected to the side surface metallization.

[0057] The flexible film and / or the further flexible film preferably has a web. The web extends in a direction transverse to a main direction of extension 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 externally contacted. This means that the line regions of the flexible film and consequently the front and / or rear contact regions of the excitation element can be electrically controlled via the connection regions of the web. The web is thus designed for externally energizing or controlling the excitation element.

[0058] In a further preferred embodiment, the arrangement comprises a housing and a cover element. The housing has an opening in which the radiation-permeable pane is arranged. A cover element is arranged on a second main side of the pane, which is opposite the first main side. The cover element is arranged in particular such that the opening is hermetically sealed by the cover element together with the pane. This means in particular that the cover element extends from the pane to the housing. Any possible gap between the pane and the housing is thus covered by the cover element as far as the second main side is concerned.

[0059] The cover element is, for example, a film and is preferably formed from a plastic such as polyimide. A diameter of the cover element is preferably larger than a diameter of the disk. For example, the diameter of the disk is 21 mm and the diameter of the cover element is 30 mm. A gap between the disk and the housing can be 2 mm. The cover element can be annular, wherein, when viewed from the second main side, an opening in the cover element can be seen. The cover element is preferably attached to the disk and the housing by means of adhesive.

[0060] The cover element advantageously prevents moisture, dirt, or other contaminants from penetrating the interior of the housing. Furthermore, the cover element can increase the mechanical stability of the pane in the housing. By forming the cover element as a film, a relatively high degree of freedom of movement of the pane in the housing can be achieved.

[0061] Furthermore, a method for operating an optical arrangement is specified. The method can be used, in particular, to operate an optical arrangement described here. This means that all features disclosed for the optical arrangement are also disclosed for the method, and vice versa.

[0062] The method for operating the optical arrangement comprises

[0063] Exciting at least one rotationally symmetrical bending mode in the central region of the disk by means of the excitation element, such that the disk is excited to at least a first bending oscillation, the first bending oscillation being a standing wave, and the first bending oscillation having nodes in the edge region of the disk. This means in particular that the first bending oscillation has maxima and minima in the middle or in the center of the disk. Deformation of the disk decreases towards the edge region of the disk and falls to zero or essentially zero at the edge of the disk. This means that by means of the first bending oscillation the disk is only deformed and oscillates in the central region. A deformation or oscillation in the edge region is not excited or reached by the rotationally symmetrical bending mode or the first bending oscillation. The first bending oscillation comprises in particular a wave train.

[0064] The method for operating the optical arrangement further comprises exciting at least one non-rotationally symmetric bending mode at least in the edge region of the disc by means of the excitation element, so that the disc is excited to a second bending oscillation at least in the edge region, wherein the second bending oscillation is a traveling wave and the second bending oscillation has traveling nodes in the edge region.

[0065] 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 migrate along a contour of the disk. This means that, on average, no region of the edge region is at rest, since the disk is deformed in every area in the edge region by the traveling wave during operation.

[0066] In particular, the traveling wave has at least two wave trains. For example, the traveling wave can have two or three wave trains, depending on the control of the excitation element.

[0067] The method further comprises superimposing the rotationally symmetric bending modes and the non-rotationally symmetric bending modes to form a total bending oscillation of the disk. Thus, the total bending oscillation of the disk is composed of the first bending oscillation and the second bending oscillation in a non-trivial manner.

[0068] A superposition of the rotationally symmetric bending modes and the non-rotationally symmetric bending modes ensures, in particular, that during operation of the optical arrangement, the disk is, on average, not at rest in any area. This means, in particular, that during operation, the disk is deformed and moved in every area or point on the second main side. This advantageously allows a cleaning effect of the disk to be achieved in all areas and points of the disk.

[0069] Further advantages and advantageous embodiments and further developments of the optical arrangement and of the method for operating the optical arrangement emerge from the exemplary embodiments presented below in conjunction with schematic drawings. Identical, similar and similarly acting elements are provided with the same reference symbols in the figures. The figures and the relative sizes of the elements shown in the figures are not generally to scale. Rather, individual elements may be shown exaggeratedly large for clarity and / or better understanding.

[0070] Figures 1 to 4 show an optical arrangement described here according to a first embodiment in different views,

[0071] Figure 5 is a perspective view of a flexible film for an optical arrangement described here,

[0072] Figure 6 is a perspective sectional view of an optical arrangement described here according to a second embodiment,

[0073] Figures 7 to 17 show various embodiments of contact areas of an excitation element for an optical arrangement described here,

[0074] Figures 18A to 21D show various exemplary bending vibrations that can be excited during operation of a disk of an optical arrangement described here.

[0075] Figures 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 disk 2 of the optical arrangement 1. The optical arrangement 1 comprises a radiation-permeable disk 2 and an excitation element 3 on a first main side 21 of the disk 2. The optical arrangement 1 is in particular a cover for a camera or a camera lens. Preferably, the disk 2 is radiation-permeable to radiation that is to be captured by the camera. The optical arrangement 1 is in particular part of a lens cleaning system for the camera lens.

[0076] The excitation element 3 is a piezoceramic excitation element and is formed from a piezoceramic. By applying a voltage to the excitation element 3, it can be expanded or contracted. Thus, a deformation of the disc 2 can be induced by the excitation element 3.

[0077] The disk 2 is circular and the excitation element 3 is annular. An outer diameter 31 of the excitation element 3 substantially corresponds 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, also 21 mm. A thickness 24 of the disk 2 is, for example, 1.5 mm and a thickness 34 of the excitation element 3 is, for example, also 1.5 mm. The thicknesses 24, 34 are measured perpendicular to the first main side 21.

[0078] The disk 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 directions parallel to the first main side 21. The excitation element 3 is designed to excite a rotationally symmetric bending mode in the central region 4. The rotationally symmetric bending mode deforms the disk 2 in the central region, so that a first bending oscillation of the disk 2 is excited in the central region 4. The first bending oscillation is rotationally symmetric. This means that during operation of the optical arrangement 1, the first bending oscillation in the central region 4, preferably in the middle of the disk 2, has alternating local maxima and local minima, which decrease in the direction of the edge region 4. In the edge region 4, the first bending oscillation has essentially no amplitude.This means that by exciting the rotationally symmetric bending mode no deformation or movement of the disc 2 in the edge region 5 can be achieved.

[0079] In addition, the excitation element 3 is designed to excite non-rotationally symmetric bending modes in the edge region 5. In particular, during normal operation, three non-rotationally symmetric bending modes are excited in the edge region 5. A superposition of the three non-rotationally symmetric bending modes results in a traveling wave in the edge region 5. A second bending oscillation, which is formed by the traveling wave, has local maxima and local minima in the edge region, which move along a contour of the disk 2 in the edge region 5 during operation of the optical arrangement 1. The local maxima and local minima of the second bending oscillations decrease linearly in the direction of the central region 4.

[0080] During normal operation, the first and second bending vibrations are superimposed, resulting in a complex overall bending vibration. By superimposing the first and second bending vibrations, the entire disk 2 can be set into vibration, both in the central region 4 and in the edge region 5.

[0081] For example, the optical arrangement 1 is used as a cover or protection for a camera or camera lens. In this case, there is basically the desire to protect the camera or camera lens from dirt or water and, if necessary, to remove dirt and water from the camera and camera lens, in other words to clean the pane 2 of the optical arrangement 1. This cleaning is achieved by ultrasonic cleaning. The pane 2 is set into 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 be used, for example, as a cover for optical sensors, for example in the automotive sector, or for surveillance cameras, particularly outdoors.

[0082] 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 pane 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 contact. The connection points are electrically conductively connected to the conduction regions of the flexible film 10. The excitation element 3 can therefore be electrically contacted via the web.

[0083] The composite of the disc 2, the excitation element 3 and the flexible film 10 is arranged in a housing 100. In particular, this composite is in an opening 103 of the

[0084] Housing 100 is arranged. A mechanical connection between the housing 100 and the disc 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.

[0085] 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 glued between the thread 101 and the cover 102. For example, the cover 102 is screwed or glued onto the thread 101.

[0086] The cover element 13 is arranged on a second main side 22 of the disk 2, which is opposite the first main side 21. The cover element 13 is designed as a film and formed with polyimide. The cover element 13, together with the disk 2, hermetically seals the opening 103 of the housing 100. For this purpose, the cover element 13 extends from the disk 2 to the housing 100. A gap between the housing 100 and the disk 2 is thus hermetically sealed.

[0087] The cover element 13 is annular and has an outer diameter of 30 mm. Viewed from the second main side 22, the disk 2, in particular the central region 5 of the disk 2, can be seen in an opening of the cover element 13.

[0088] Because the mechanical connection between the disk 2 and the housing 100 is formed solely by the foils 10, 13, the disk 2 has a relatively high degree of freedom of movement. This means that the damping of the overall bending vibration of the disk 2 is relatively low.

[0089] Figures 3 and 4 show the optical arrangement 1 according to the first embodiment in a perspective view. In Figure 3, a front side of the optical arrangement 1 is shown with a view of the second main side 22 of the disc 2, and in Figure 4, the optical arrangement 1 is shown with a view of the first main side 21 of the disc 2. As can be seen in Figures 3 and 4, the housing

[0090] 100 on a side facing away from the disc 2 a thread

[0091] 101. The optical assembly can be mounted on a camera or camera lens using thread 101.

[0092] Figure 5 shows a flexible film 10 as used in the first exemplary embodiment of the optical arrangement 1 according to Figures 1 to 4. The flexible film 10 is designed as a ring, and an outer diameter of the flexible film 10 is larger than the diameter 24 of the disk 2. Thus, the film 10 can 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 conduction regions are formed with copper.

[0093] The flexible film 10 has a web 12 that extends transversely, in particular perpendicularly, to a main extension direction 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 extension plane of the flexible film 10, these connection points are advantageously particularly easily accessible externally, as can also be seen in Figure 4.

[0094] Figure 6 shows an optical arrangement 1 according to a second exemplary embodiment in a perspective sectional view. The optical arrangement 1 according to Figure 6 differs particularly from the optical arrangement 1 according to the first exemplary embodiment in that the optical arrangement 1 according to the second exemplary embodiment has an additional flexible film 11.

[0095] 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. Like the flexible film 10, the further flexible film 11 has conductive 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 its arrangement on the excitation element 3.

[0096] By means of the flexible film 10, in particular, the front side 31 of the excitation element 3 can be electrically conductively contacted, and by means of the further flexible film 11, for example, the rear side 32 of the excitation element 3 can be electrically conductively contacted. By means of the further flexible film 11, in particular, a mechanical connection to the housing 100 is also formed.

[0097] Figure 7 shows a perspective view of the front side 31 of an excitation element 3 for an optical arrangement 1 described here. The excitation element 3 has a plurality of front-side contact regions 6. The front-side contact regions 6 are, for example, sputtered and comprise copper.

[0098] In the exemplary embodiment of Figure 7, the excitation element 3 has two front-side contact areas of the first type 61, two front-side contact areas of the second type 62, and two front-side contact areas of the third type 63. Clockwise, as viewed from the front side 31, a contact area of ​​the second type 62 follows a contact area of ​​the first type 61. Further, a contact area of ​​the second type 62 is followed by a contact area of ​​the third type 63, which is then again followed by a contact area of ​​the first type 61.

[0099] During normal operation, a first voltage is applied to the contact areas of the first type 61, a second voltage to the contact areas of the second type 62, and a third voltage to the contact areas of the third type 63. The applied voltages can deform the excitation element 3, which comprises a piezoceramic. This deformation is transferred to the disk 2. With suitable control of the excitation element 3, the disk can be set into vibration. This means that by means of the first, second and third voltages, three non-rotationally symmetric bending modes can be excited in the edge region 5 of the disk 2. A superposition of these bending modes results in the second bending vibration.

[0100] In the exemplary embodiment in Figure 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 disk 2 (see Figure 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 120° out of phase with the first voltage. The third voltage is 240° out of phase with the first voltage.

[0101] Furthermore, during operation, a fourth voltage is applied to the contact regions 6, which is applied jointly to all 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. The fourth voltage can be used to excite the rotationally symmetric bending mode and consequently the first bending oscillation in the central region 4 of the disk 2. The overall bending oscillation can thus be generated by simultaneously applying or suitably superimposing the first, second, third and fourth voltages.

[0102] Figure 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 on the front side 31. The front-side contact regions 6 of the first type 61, the second type 62, and the third type 63 follow one another in the order described in connection with Figure 7.

[0103] In a manner analogous to that described in connection with Figure 7, a first voltage can be applied to the contact areas of the first type 61, a second voltage to the contact areas of the second type 62, a third voltage to the contact areas of the third type 63, and then a fourth voltage to all front-side contact areas 6. In contrast to the embodiment of Figure 7, a second bending vibration can be excited with the contact areas 6 according to Figure 8, which second bending vibration has three wave trains. This means that the traveling wave in the edge area 5 has three maxima and three minima (see Figure 20).

[0104] Figure 9 shows a perspective view of the rear side 32 of the excitation element 3 according to Figures 7 or 8. The rear side 32 has a ground contact 8. This means that the rear side 32 is preferably free of an electrical potential. The ground contact 8 forms, in particular, the entire rear side of the excitation element 3.

[0105] In contrast to Figures 7 to 9, it is possible for the front side 31 to have the ground contact 8 and the rear side 32 to be provided with rear contact regions 7, in particular rear contact regions of the first type 71, the second type 72, and the third type 73. The rear contact regions 7 are arranged on the rear side 32 in a manner analogous to the front contact regions 6. In this case, electrical contact is made in a manner analogous to the electrical contact of the front contact regions 6, as described in connection with Figures 6 and 7.

[0106] Figures 10 and 11 show the excitation element 3 according to Figures 7 and 9 in a perspective view, wherein the excitation element 3 of Figure 10 additionally has a metallization 9 on a side surface 35. The side surface 35 connects in particular the front side 31 to the back side 32. The ground contact 8 can be pulled from the back side 32 to the front side 31 via the metallization 9. This means that the metallization 9 forms a re-contact for the ground contact 8. The ground contact 8, like the front-side contact elements 6, can therefore be electrically contacted via the front side 31. The excitation element 3 can therefore be electrically contacted via the flexible film 10, as shown for example in Figure 1.

[0107] 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 contact regions 7, wherein the ground contact 8 of the front side 31 is drawn to the rear side 32 via the metallization 9. In this case, electrical contact with the excitation element 3 can be established exclusively via the rear side 32.

[0108] It is also possible for the excitation element 3 to have front-side contact areas 6 and rear-side contact areas 7. Via metallizations 9 on the side surface 35, the front-side contact elements 6 can be reconnected to the rear side 32, or the rear-side contact elements 7 can be reconnected to the front side 31. In this case, it is possible for electrical contact between the front and rear contact areas 6, 7 to be established exclusively from the direction of the front side 31 or the rear side 32.

[0109] Figures 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, the second type 72, and the 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, the second type 62, 72, and the third type 63, 73 is correspondingly as described in Figure 7.

[0110] In a projection onto a common plane parallel to the front side 31, i.e., for example, a plane in which the front side 31 lies, the front contact areas 6 overlap with the rear contact areas 7. Such an overlap is, in particular, complete. This means that, in the projection onto the common plane, the front contact areas 6 completely cover the rear contact areas 7, and vice versa. Each front contact area of ​​the first type 61 overlaps with a rear contact area of ​​the second type 62. Each front contact area of ​​the second type 62 overlaps with a rear contact area of ​​the third type 73. Each front contact area of ​​the third type 63 overlaps with a rear contact area of ​​the first type 71.

[0111] Electrical contact between the contact regions 6, 7 is made 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 the amplitude. The modified first voltage has an amplitude that is lower than the first voltage by a factor of 1:3. The same applies accordingly to the modified second and the modified third voltage. Figures 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 analogously to the front-side contact regions 6 according to Figure 8.In a projection onto the front side 31, the front contact areas 6 and the rear contact areas 7 overlap, in particular, completely. Each front contact area of ​​the first type 61 overlaps with a rear contact area of ​​the second type 62. Each front contact area of ​​the second type 62 overlaps with a rear contact area of ​​the third type 73. Each front contact area of ​​the third type 63 overlaps with a rear contact area of ​​the first type 71.

[0112] As with the arrangement of the contact areas 6, 7 according to Figures 12 and 13, the modified first voltage, the modified second voltage, the modified third voltage and the fourth voltage can be applied to the contact areas 6, 7 of Figures 14 and 15 in order to generate the overall bending vibration in the disc 2.

[0113] Figure 16 shows a combined view of a front side 31 and a back side 32 of an excitation element 3. On the front side 31, the excitation element 3 comprises a front contact region of the first type 61, a front contact region of the second type 62 and a front contact region of the third type 63. On the back side 32, represented by the inner ring in Figure 16, the excitation element comprises a back contact region of the first type 71, a back contact region of the second type 72 and a back contact region of the third type 73. The front contact regions 6 and the back contact regions 7 are arranged offset from one another in a projection into a common plane, for example the front side 31. This means in particular that in the projection each front contact region 6 overlaps with at least two back contact regions 7 and vice versa.Compared to Figures 12 and 13, the proportion of the front contact areas 6 and rear contact areas 7 can be reduced, and simultaneously, by applying the first, second, third, and fourth voltages, the first and second bending oscillations can be excited. The second bending oscillation comprises two wave trains.

[0114] Figure 17 shows an embodiment of an excitation element 3 described here, viewed from the front side 31 and rear side 32, in which the front contact regions 6 and the rear contact regions 7 are arranged offset from one another. The exemplary embodiment of Figure 17 differs from the exemplary embodiment of Figure 16 in particular in that three wave trains can be excited in the second bending oscillation with the excitation element 3 of Figure 17. Therefore, Figures 16 and 17 differ in the front contact regions 6 and the rear contact regions 7.

[0115] In the embodiments of Figures 16 and 17, in the projection onto the common plane, each front-side contact region of the first type 61 overlaps with a rear-side contact region of the second type 72 and a rear-side contact region of the third type 73. Furthermore, each front-side contact region of the second type 62 overlaps with a rear-side contact region of the first type 71 and a rear-side contact region of the third type 73. In addition, each front-side contact region of the third type 63 overlaps with a rear-side contact region of the first type 71 and a rear-side contact region of the second type 71.

[0116] This arrangement of the front and rear contact areas 6, 7 satisfies a predetermined polarity direction 60, represented by the arrows 60 in Figures 16 and 17. The polarity direction 60 points from a contact area of ​​the first type 61, 71 to a contact area of ​​the third type 63, 73, from a contact area of ​​the second type 62, 72 to a contact area of ​​the first type 61, 71, and from a contact area of ​​the first type 61, 71 to a contact area of ​​the third type 63, 73 to a contact area of ​​the second type 62, 72.

[0117] The polarity direction 60 is predetermined by the sequence of contact areas of the first type, second type and third type. The polarity direction 60 ensures in particular that during operation there is a phase shift between the first voltage and the second and third voltages such that a superposition of the three bending modes produces a standing wave. This is achieved in Figures 16 and 17 in particular in that, viewed counterclockwise in the polarity direction 60, a contact area of ​​the first type 61, 71 is followed by a contact area of ​​the third type 73, 63, a contact area of ​​the third type 73, 63 is followed by a contact area of ​​the second type 62, 72, and a contact area of ​​the second type 62, 72 is followed by a contact area of ​​the first type 71, 61. Thus, in the polarity direction 60, the sequence of the first, second and third contact areas 61, 71, 62, 72, 63, 73 in Figures 16 and 17 corresponds to Figures 14 and 15.Therefore, with the arrangement of the contact areas 6 according to Figures 16 and 17, similar or identical modes can be excited in the disc 2 as in Figures 14 and 15, wherein the total number of contact areas 6 is reduced compared to Figures 14 and 15.

[0118] Figures 18A and 18B illustrate a first bending oscillation, such as may occur during operation of the optical arrangement 1. Figure 18A illustrates a deformation 80 of the disk 2 at a first time, and Figure 18B illustrates the deformation 80 at a later time during a period of the first bending oscillation.

[0119] During the first bending vibration, the disk 2 deforms in the central region 5. This means that the deformation 80 of the disk 2 is maximum in the central region. In the embodiment shown in Figure 18, the maximum deformation is, for example, 2.3 • 10- The deformation decreases towards the edge region and amounts to 0 m or essentially 0 m in the edge region. During operation of the optical arrangement 1, the disk 2 oscillates so that the deformation 80 reaches a maximum in the central region and decreases to zero over time before returning to its maximum value.

[0120] Figures 19A and 19B illustrate the second bending oscillation, wherein a traveling wave of the second bending oscillation 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 traveling wave and maxima and minima of the second bending oscillation migrate along a contour of the disk 2. Figure 19A shows a deformation 80 at a first point in time and Figure 19B shows the deformation 80 at a later second point in time during a period of the second bending oscillation. As can be seen from the comparison, the maxima and minima have migrated along the contour of the disk 2. A maximum deformation 80 of the disk 2 is approximately 8.3 m .

[0121] Figure 20 illustrates a second bending oscillation of the disk 2. Figure 20 shows a deformation 80 of the disk 2 at two different points in time, Figure 20A at a first point in time, Figure 20B at a later second point in time during a period of the second bending oscillation. In contrast to the second bending oscillation in Figure 19, the second bending oscillation in Figure 20 has three wave trains. Like Figure 19, the second bending oscillation in Figure 20 is a traveling wave, with the local maxima and minima traveling along the contour of the disk 2. A maximum deformation 80 is approximately 3.5 • 10-^ m.

[0122] Figure 21 shows a total bending oscillation resulting from the superposition of the first and second bending oscillations of the disk 2. Figure 21A shows a deformation 80 of the disk 2 at a first point in time, Figure 21B shows the deformation 80 at a later second point in time, Figure 21C shows the deformation 80 at a further later point in time, and Figure 21D shows the deformation 80 at a further later point in time during a period of the total bending oscillation.

[0123] As can be seen from Figures 21A to 21D, local maxima and minima form both in the edge region and in the central region of the disk 2. A maximum deformation 80 of the disk 2 amounts to approximately 4.5 • 10-7 m. As can be seen in Figure 21, a superposition of the first and second bending oscillations causes essentially all regions or all points of the disk 2 to bend or oscillate or vibrate or move during operation of the optical arrangement 1. Thus, by combining the first and second

[0124] Bending vibration, i.e. a superposition of the rotationally symmetric bending modes and non-rotationally symmetric bending modes, excite an overall bending vibration, by which the disc 2 essentially in all

[0125] areas during operation of the optical arrangement 1. This allows the optical arrangement 1 to be ultrasonically cleaned of dirt, water residues, or rain using the overall bending vibration. Advantageously, the cleaning effect is not limited to the central area, but can be achieved in all areas of the pane 2.

[0126] Reference sign

[0127] 1 optical arrangement

[0128] 2 radiation-permeable pane

[0129] 3 piezoelectric excitation element

[0130] 4 Central area

[0131] 5 Marginal area

[0132] 6 front contact areas

[0133] 7 rear contact areas

[0134] 8 Ground contact

[0135] 9 Metallization

[0136] 10 flexible foil

[0137] 11 additional flexible foil

[0138] 12 jetty

[0139] 13 Cover film

[0140] 21 first main page

[0141] 22 second main page

[0142] 23 diameters

[0143] 24 thickness

[0144] 31 Front

[0145] 32 Back

[0146] 33 Outer diameter of the excitation element

[0147] 34 thickness

[0148] 35 side surface

[0149] 60 polarity direction

[0150] 61 front contact of the first kind

[0151] 62 front contact of the second type

[0152] 63 front contact of the third kind

[0153] 71 rear contact of the first kind

[0154] 72 rear contact of the second type

[0155] 73 rear contact of the third kind

[0156] 80 Deformation

[0157] 100 Housing 101 Thread

[0158] 102 Cover

Claims

Patent claims 1. Optical arrangement (1) comprising a radiation-permeable 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-permeable pane (2) has a central region (4) and an edge region (5) surrounding the central region, - the excitation element (3) is designed to be arranged in the central region (4) of the radiation-permeable disc (2) to excite at least one rotationally symmetric bending mode, and - the excitation element (3) is designed to excite at least one non-rotationally symmetric bending mode in the edge region (5) of the radiation-transmissive pane (2), which bending mode generates a traveling wave in the edge region (5) is generated.

2. Arrangement (1) according to claim 1, wherein - the radiation-permeable disc (2) is circular, - the excitation element (3) is ring-shaped, - an outer diameter (33) of the annular excitation element (3) substantially corresponds to a diameter (23) corresponds to 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 separated from the Excitation element (3) is covered.

3. Arrangement (1) according to claim 1 or 2, wherein - the excitation element (3) is arranged on a front side facing the first main side (21) of the disc (2) (31) a plurality of front contact areas (6), and - the front contact areas (6) can be electrically contacted independently of one another.

4. Arrangement (1) according to one of the preceding claims, wherein - the excitation element (3) has a plurality of rear contact areas (7) on a rear side (32) facing away from the first main side (21), and - the rear contact areas (7) can be electrically contacted independently of one another.

5. Arrangement (1) according to claims 3 and 4, wherein - the front contact areas (6) and the rear contact areas (7) can be electrically contacted independently of one another, and - in a projection into a common plane parallel to the front side (31), the front contact areas (6) are arranged offset from the rear contact areas (7).

6. Arrangement (1) according to one of claims 3 or 4, wherein a ground contact (8) is arranged on a side of the excitation element (3) which is opposite the contact areas (6, 7).

7. Arrangement (1) according to one of claims 3 to 6, wherein a distance between two adjacent front contact areas (6) and / or two adjacent rear contact areas (7) is between 0.2 mm and 1 mm inclusive.

8. 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 contact areas (6) and / or two adjacent rear contact areas (7) is between one third and one half of the thickness (34) of the excitation element (3).

9. Arrangement (1) according to one of the preceding claims, wherein - the excitation element (3) has at least one front contact area (6) and at least one rear contact area (7), and - the excitation element (3) has at least one metallization (9) on a side surface (35) which electrically conductively connects at least one front-side contact region (6) and at least one rear-side contact region (7) to one another.

10. Arrangement (1) according to one of the preceding claims, wherein a flexible film (10) is arranged between the radiation-permeable pane (2) and the excitation element (3), the flexible film (10) having independently controllable electrical conduction regions which are electrically conductively connected to the excitation element (3).

11. Arrangement (1) according to claim 10 further comprising a housing (100), wherein a mechanical connection between the housing (100) and the disc (2) and / or the excitation element (3) is formed by the flexible film (10).

12. Arrangement (1) according to claim 10 or 11 with reference to claim 3 or 4, wherein the conduction regions of the flexible film (10) are electrically conductively connected to the front contact regions (6) or rear contact regions (7).

13. 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 independently controllable electrical conduction regions which are electrically conductively connected to the excitation element (3).

14. Arrangement (1) according to claim 13 with reference to claim 11, wherein the further flexible film (11) provides a further mechanical connection between the housing (100) and the disc (2) and / or the Excitation element (3) is formed.

15. Arrangement (1) according to claim 13 or 14 with reference to claim 3 and 4 or with reference to claim 5, wherein the conduction regions of the flexible film (10) between the pane (2) and the excitation element (3) are electrically conductively connected to the front-side contact regions (6), and the further conduction regions of the further flexible film (11) are electrically conductively connected to the rear-side contact regions (7).

16. Arrangement (1) according to one of claims 10 to 15 with reference 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).

17. 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 extension direction of the flexible film (10), and - the web (12) has connection areas via which the line areas of the flexible film (10) can be externally contacted.

18. 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-permeable disc (2) is arranged, - the cover element (13) is arranged on a second main side (22) of the disc (2) which is opposite the first main side (21), and - the opening (103) is hermetically sealed by the cover element (13) together with the disk (2).

19. A method for operating an optical arrangement (1) according to one of the preceding claims, comprising: - Excitation of at least one rotationally symmetric bending mode in the central region (4) of the disc (2) by means of the excitation element (3), so that the disc is excited to at least a first bending oscillation, wherein the first bending oscillation is a standing wave and the first bending vibration has node points in the edge region (5), - Excitation of at least one non-rotationally symmetric bending mode at least in the edge region (5) of the disc (2) by means of the excitation element (3), so that the disc (2) is excited to a second bending oscillation at least in the edge region (5), wherein the second bending oscillation is a traveling wave and the second bending oscillation has traveling nodes in the edge region - Superposition of the rotationally symmetric bending mode and the non-rotationally symmetric bending mode to form an overall bending vibration of the disc (2).

20. The 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 vibration has at least two wave trains.

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