Mirror shutter system

Abstract

Mirror-shutter system (100) comprising a plurality of microelements (1) which are configured as micromirrors and / or as microshutters, wherein each microelement (1) has an opaque surface body which is hinged on a translucent base plate (2) of the mirror-shutter system (100) by means of an edge-side mounting section (11), such that each microelement (1) is pivotable between an opaque closed position and at least one translucent open position, wherein the microelements (1) each have a layer structure comprising at least one compression layer (1a) and one tension layer (1b), wherein a compression compensation layer (1c) is arranged on the tension layer (1b) along a sheet section (12) of each microelement (1), such that each microelement (1) is subdivided into the following sections: - the leaf section (12), which is globally stress-free and has two essentially plane-parallel surfaces, - the edge-side mounting section (11), which is rigidly arranged on the base plate (2) of the mirror shutter system (100), and - an intermediate hinge section (13) which has a residual stress-induced curvature, whereby an open position of the microelement (1) is formed, wherein the totality of the microelements (1) in the respective closed position forms an irregular or unstructured lattice.

Description

[0001] The invention relates to a mirror shutter system comprising a plurality of microelements which are designed as micromirrors and / or as microshutters, wherein each microelement has an opaque sheet which is arranged in a hinge-like manner on a translucent base plate of the mirror shutter system by means of an edge-side fastening section, such that each microelement is pivotable between an opaque closed position and at least one translucent open position. STATE OF THE ART

[0002] Systems of shutters and mirrors, also known as shutter arrays and mirror arrays, which are constructed from a large number of actuatable microelements in the form of microshutters or micromirrors, belong to the so-called micro-opto-electro-mechanical systems (MOEMS) and are used for high-resolution light modulation or light guidance in a large number of different applications as projector elements (in particular the projection technology from Texas Instruments Inc. known under the brand name Digital Light Processing), routers, shutters or apertures, for example in the fields of optical information processing, projection displays, microscopy, endoscopy, lithography, laser structuring or as sunlight-conducting elements in the glazing of buildings.

[0003] The microelements constituting the system are miniaturized optical elements ranging in size from a few square micrometers to square millimeters, whose position, and thus their light-technical effect, can be actuated by active or passive control. The microelements are designed either as purely light-absorbing microshutters or, as micromirrors, they have at least one reflective surface. Typical thin-film processes are used to manufacture the system, particularly using deposition processes, lithography and etching steps, and sacrificial layer technologies.

[0004] For example, DE 103 58 967 A1 discloses a system in the form of a micromirror array for facade construction purposes, in which micromirror elements are arranged in a regular, planar matrix arrangement and are controlled individually or in groups via an addressing network by a central control unit. This creates the possibility of active sunlight steering with high spatial resolution, which enables a needs-based and personalized lighting situation in the space behind the facade. Detailed information on the production, function, and application principle of such a micromirror system can be found in HILLMER, Hartmut [et al.]: Optical MEMS-based micromirror arrays for active light steering in smart windows. In: Japanese Journal of Applied Physics, Vol. 57, 2018, H. 8S2, p. 08PA07. ISSN 1347-4065 (E); 0021-4922 (P). DOI: 10.7567 / JJAP.57.08PA07. URL: https: / / iopscience.iop.org / article / 10.7567 / JJAP.57.08PA07 / pdf [accessed on November 19.2020].

[0005] US 2009 / 0142050 A1 discloses a shutter system that performs the function of an iris diaphragm. For this purpose, the shutter system has a base plate with a circular, translucent section, over which a plurality of microshutters in the form of rollable, opaque diaphragm elements are arranged. In the unrolled, i.e., closed, state, the diaphragm elements each have an identical triangular contour, and in their regular arrangement, the entirety of the diaphragm elements covers the translucent section of the base plate. The diaphragm elements have a layered structure, wherein the residual stresses of the different layers are such that the diaphragm elements roll up. An electrostatic actuation principle is implemented to counteract this rolling up and to transfer and hold the diaphragm elements in the closed position.The intention is to actuate all aperture elements simultaneously and uniformly.

[0006] US 2009 / 0040586 A1 discloses a micromirror system with aperture function, comprising a plurality of micromirrors configured to provide an adjustable aperture with a variety of aperture sizes by controlling the movements of the micromirrors. Furthermore, the micromirrors included in the aperture can form a micromirror array lens with variable focusing function.

[0007] US 2008 / 0049291 A1 discloses a micromirror array lens comprising a plurality of micromirrors arranged on a flat or curved surface to reflect incident light, each micromirror being individually movable. The micromirror array lens can form various optical elements, such as a variable focal length lens, a fixed focal length lens, an array of optical switches, a beam guider, a zone plate, a shutter, an aperture, a multifocal length lens, or other multifunctional optical elements.

[0008] WO 2008 / 075778 A1 discloses electrostatically actuatable thin-film structures for the formation of optical microelements, in particular as systems of micro-apertures or micro-mirrors.

[0009] Furthermore, shutter systems can serve as ring-shaped apertures in the illumination or imaging system in microscopy, for example in dark-field microscopy, interference microscopy or STED microscopy.

[0010] Particularly for demanding optical applications, one disadvantage of state-of-the-art shutter and mirror systems is the occurrence of disruptive artifacts in light modulation. In this context, diffraction effects are the first to be mentioned. The entirety of the small-scale microshutters or micromirrors forms an optical grating, which inevitably leads to diffraction effects during light passage. The diffractive structures are formed in particular by the attachment sections of the individual microelements, which are arranged rigidly on the system's base plate, for example as strip-shaped structures, or by material webs remaining between the individual microelements on the base plate due to manufacturing requirements, which outline the contours of the closed microelements.Diffraction at such an optical grating leads to a concentration of light around the principal diffraction directions (zero order) and to the propagation of light with attenuated intensity in deviating directions (higher diffraction orders). This can lead to undesirable inhomogeneities, blurring perceived by the observer, or color fringing. Another undesirable optical artifact is so-called ghost images, which can occur in mirror systems. Ghost images arise when the micromirrors are open or partially open. The image that the observer perceives when looking through the open or partially open mirror system is, at certain viewing angles, a superposition of the directly transmitted light (desired, viewing direction) with a ghost image reflected by the micromirrors (undesired).Even if the ghost image is very weak, it still interferes with the clear view through the mirror system, for example when used in a microscope or a window. DISCLOSURE OF THE INVENTION

[0011] It is therefore the object of the present invention to propose a generic mirror shutter system which allows a variable and spatially high-resolution modulation in the transmission and reflection of incident light, wherein in particular the transmission should be impaired by as few diffraction artifacts and ghost images as possible.

[0012] This object is achieved by a mirror shutter system according to claim 1. Advantageous developments of the invention are specified in the dependent claims.

[0013] The invention includes the technical teaching that the totality of the microelements forms an irregular or unstructured lattice in the respective closed position.

[0014] A core concept of the invention is to design the microelements with regard to their individual contour, size, and orientation relative to one another in such a way that their entirety is as structurally unstructured and random as possible, i.e., that in particular, as few parallel and / or equidistantly arranged diffracting structures as possible are present. Thus, when light passes through a mirror-shutter system according to the invention, grating diffraction effects—i.e., those diffraction effects resulting from the interference of light waves passing through different microelements—occur only to a very small extent, resulting in significantly more homogeneous light modulation and a clearer view for the viewer compared to prior art shutter systems.

[0015] The terms used here regarding different grid types are explained in more detail below.

[0016] The entirety of the microelements forms an essentially gapless and overlap-free partition of the light-active surface of the mirror-shutter system. This formally corresponds to a grid whose grid cells are formed by the microelements, with the corners and sides of the, for example, polygonal contours of the microelements representing the grid points and grid lines, respectively. The essential feature of the invention, which addresses the problem of diffraction artifacts, is expressed in the topology of the grid formed by the microelements.

[0017] The various grid types can be classified into structured and unstructured grids.

[0018] Structured grids have a regular topology, meaning that the grid cells are arranged in a regular grid, regardless of their cell geometry. In particular, the grid cells of structured grids can be uniquely indexed by tuples of integers, or in the case of a two-dimensional surface grid, by index pairs. If all grid cells of a structured grid have the same geometry - in this case it is referred to as a regular grid - the only information required to construct the entire grid is the grid origin, the orientation of the grid axes, the side lengths of the grid cells, and the number of grid cells per grid axis. The grid axes can, in particular, span a Cartesian coordinate system; however, for example,Polar coordinate representations are also suitable, for example to partition a circular area by a structured grid of ring segments, where the index pairs in this case denote a radial and a polar angle component. Regular grids, i.e. structured grids with similar grid cells, have a high degree of regularity and / or periodicity, i.e. they are characterized in particular by a large number of parallel and / or equidistant grid lines. In the present application of a grid made of microelements, this grid structure leads to disadvantageous diffraction effects of light passing through the aperture device. In the case of open microelements, the diffracting structures are formed by the edges of their surface bodies and the edge-side attachment sections of the individual microelements, as well as by the edges of closed microelements in the vicinity of an open microelement.In addition, as already mentioned above, due to the manufacturing process, web-shaped borders of the microelements can be arranged on the base plate of the mirror shutter system, the edges of which also contribute to light diffraction.

[0019] According to the invention, it is proposed to design the microelements with regard to their geometry, size and relative arrangement in such a way that their entirety forms an irregular or unstructured lattice.

[0020] An irregular grating is a structured grating composed of grid cells of different shapes. For example, the individual grid cells can have polygonal contours that differ at least partially from one another in the number of grid points and grid lines, as well as the angles enclosed by the grid lines. While such an irregular grating can be mapped onto a regular grating, it exhibits parallel and / or periodic structures to a significantly lesser extent, resulting in significantly more diffuse or almost no light diffraction patterns.

[0021] Unstructured gratings represent the most general grating type and exhibit neither a regular topology nor a uniform grid cell geometry. A specification for their construction must include the connectivity of each grid point with surrounding grid points. Unstructured gratings exhibit a particularly low degree of order and regular structures and are therefore particularly suitable for the purposes of the present invention for generating a low-structure diffraction pattern upon light transmission.

[0022] In an advantageous embodiment, the microelements each have an irregular polygonal contour in the closed position. The contour refers to the outline of the planar body forming the microelement in its main plane of extension. In the closed position, the microelements preferably assume a planar shape. In contrast to a regular polygon, an irregular polygon is characterized in that not all sides have the same length, and different angles are included between the sides. This ensures that the mirror-shutter system contains as few similar structures as possible, in particular as few parallel or equidistantly arranged line structures as possible. In particular, the edge side of the microelement that forms the fastening section can also be oriented differently from microelement to microelement.

[0023] Preferably, the number of sides of the polygonal contours of the microelements is between three and eight. This offers sufficient geometric variation possibilities to achieve the inventive structural simplicity of the entire microelement assembly. With even more complex contours or unfavorable angle combinations, there is also a risk of mutual entanglement when pivoting the microelements between the different positions.

[0024] In a further advantageous embodiment, the microelements, in the closed position, each have a contour consisting of at least partially curved lines. Such curved contours represent a further design option for varying the microelements and thus contribute to the inventive realization of light transmission with the lowest possible diffraction.

[0025] In particular, the mirror shutter system comprises actuating means for pivoting the microelements between the at least one open position and the closed position, wherein individual microelements and / or groups of microelements can be actuated by means of the actuating means. Electrostatically, magnetically, or thermally acting actuating means, for example, are known from the prior art. Preferably, the actuation is based on a concept in which groups of microelements can be pivoted simultaneously. The size and contour of such groups must be adapted both to the requirements of the addressed application and to the manufacturing constraints regarding passive addressing.

[0026] In a specific embodiment of the mirror shutter system according to the invention, the entirety of the microelements forms a circular, elliptical, or polygonal shape, or a freeform, wherein ring-segment-shaped groups of microelements can be actuated by means of the actuating means. This embodiment serves to form ring apertures with variable diameters and aperture angles, for example, for use in optical instruments.

[0027] In an advantageous embodiment, the actuating means constitute an electrostatic operating principle, for which the base plate of the mirror-shutter system comprises an electrically conductive material, and the microelements comprise or form electrodes. The actuating means comprise a controllable voltage source for applying electrical voltage signals between the base plate and the electrodes. The base plate and the electrodes represent components of the actuating means, and by generating a potential difference using the voltage source, an electrostatic force can be generated between the microelements and the base plate.

[0028] Preferably, the baseplate comprises a plurality of mutually electrically insulated baseplate segments, and the electrodes are electrically connected to form a plurality of mutually electrically insulated fields, wherein the baseplate segments and the fields are each individually electrically connected to the voltage source. By applying an electrical voltage between individual baseplate segments and fields, the microelements can be specifically actuated in subfields that correspond to the geometric overlap of the active baseplate segments and fields.

[0029] The microelements of the mirror shutter system according to the invention each have a layer structure which comprises at least one compressively stressed layer and one tensilely stressed layer, wherein along a sheet section of each microelement a compressively stressed compensation layer is arranged on the tensilely stressed layer, such that each microelement is divided into the following sections: - the blade section, which is globally stress-free and has two essentially plane-parallel surfaces, - the edge-side fastening section, which is rigidly arranged on the base plate of the mirror shutter system, and - an intermediate hinge section which has a residual stress-induced curvature, whereby an open position of the microelement is formed.

[0030] Without an applied electrical voltage, the microelements are in a maximally open position, which, due to the residual stresses present, is caused by a curvature of the hinge section between the fastening section, which is positively fixed to the base plate, and the stress-compensated blade section. For example, the hinge section has a radius of curvature that is one-hundredth to one-third of the length of the longest side of the contour of the respective microelement.

[0031] Preferably, the leaf section is oriented substantially orthogonally to the base plate in the maximum open position of the respective microelement. In such a vertical position, maximum light transmission is achieved, and this position is assumed when the microelements are not subject to any electrostatic force from an applied electrical voltage, so that the hinge sections are rolled up purely according to their inherent mechanical stresses.

[0032] Between this orthogonal extreme position and the closed position of the microelements, further intermediate positions can preferably be assumed, which represent corresponding gray values ​​with regard to the transmittance. Starting from the maximum open position of the microelements, the microelements can be continuously closed by applying a continuously increasing electrical voltage between the base plate and the electrodes up to a threshold voltage at which the microelements close completely. In one embodiment of the mirror shutter system according to the invention with microelements in the form of micromirrors, this variety of adjustable orientation angles of the microelements is used by controlling the actuating means to specifically direct light.

[0033] In a further advantageous embodiment, the width of the hinge sections of different microelements varies, so that a roll-up angle of the hinge sections varies in the at least one open position of the microelements. The width of the respective hinge section refers to its extension between the fastening section and the blade section. The curvature is approximately constant along each hinge section, and the respective roll-up angle accordingly describes the central angle of the circular arc formed by the hinge section.The variation in the width of the hinge sections thus results in a variation in the position of the leaf sections around an average value in each open position of the microelements. Such a position variation is particularly advantageous in the case of microelements designed as micromirrors because it results in a significant suppression of the ghost images mentioned above and thus the quality of the optical image is further improved with the mirror shutter system according to the invention.

[0034] In an advantageous embodiment, the layer structure of each microelement comprises at least one electrically conductive layer, which forms the respective electrode. It is known from the prior art, for example, to use aluminum alloys to construct a layer stack provided with dedicated residual stresses.

[0035] Furthermore, the base plate of the mirror shutter system preferably also has a layered structure comprising a translucent, electrically conductive base layer and a translucent, electrically insulating insulation layer, with the attachment portion of each microelement being arranged on the insulation layer. The insulation layer thus serves to electrically separate the base layer from the electrodes arranged on the microelements or formed by them.

[0036] In particular, the sides of the microelement contours range in length from 1 micrometer to 2 millimeters. Taking manufacturing constraints into account, microelements of this size can address all relevant applications.

[0037] Another exemplary application of the mirror shutter system according to the invention concerns ultrafast laser safety goggles for protecting against laser attacks, for example, pilots in the cockpit during takeoff or landing of an aircraft, as well as security personnel (police and military). The goggles currently used for this purpose are based on optical filters that only protect against certain wavelengths and distort color perception, which is critical not only at night. PREFERRED EMBODIMENT OF THE INVENTION

[0038] Further measures improving the invention are presented in more detail below, together with the description of preferred embodiments of the invention, with reference to the figures. They show: Fig. 1 a plan view of fields and microelements of a first embodiment, Fig. 2 a perspective view of a section of the first embodiment with partially opened microelements, Fig. 3 an exploded view of the fields and the base plate of the first embodiment, Fig. 4 a representation of the first embodiment of the mirror shutter system according to the invention, Fig. 5 exemplary switching states of the first embodiment, Fig. 6 a plan view of microelements of a second embodiment, Fig. 7 a plan view of microelements of a third embodiment, Fig. 8 a perspective view of a fourth embodiment with partially opened microelements, Fig. 9 a plan view of microelements of a fifth embodiment, and Fig. 10 and Fig. 11 schematic cross-sectional partial views of a microelement of a mirror shutter system according to the invention.

[0039] Fig. 1 shows a plan view of fields 10a-10e and microelements 1 of a first mirror shutter system 100 according to the invention. The microelements 1 are electrically interconnected to form the mutually electrically insulated fields 10a-10e. The entirety of the microelements 1 forms a circular shape, which is segmented into the four annular fields 10b-10e and the circular inner field 10a. Each of the five fields 10a-10e can be subjected to an electrical potential independently of the other fields. The enlarged partial views show the two inner fields 10a and 10b, as well as their structure from the individual microelements 1. The microelements 1 comprise the blade section 12 and the edge-side fastening section 11, which is indicated here only as a line and over which the microelements 1 are arranged on the base plate of the mirror shutter system 100.The irregular polygonal contours of microelements 1 here have three, four, or five sides and vary among themselves in terms of their geometric aspect ratios and surface areas. In the closed position shown here, the entirety of microelements 1 forms an unstructured lattice.

[0040] Depending on the application, the microelements 1 can be designed as micromirrors or as microshutters, i.e. they can either be used to specifically direct light or to vary the degree of transmission. This applies not only to the exemplary embodiment shown here, but can in principle apply to any mirror-shutter system according to the invention. Based on a thin-film process used for production, the microelements 1 are usually made of a metal, so that a mirror effect is also present in microelements 1 that function as microshutters. If required, the mirror effect can be suppressed, for example by setting a pronounced surface roughness of the microelements 1 during production. If the mirror effect is otherwise desired, particularly smooth surfaces can be used during production, whereby these can be used as a wear protection measure if necessary.can still be sealed with a hard and transparent protective layer, e.g. made of TiO2.

[0041] Furthermore, dielectric multilayer mirrors can be applied to increase reflectivity or spectral properties. In principle, it may also be advantageous for specific applications to provide a mirror-shutter system 100 according to the invention, whose microelements 1 are designed partly as micromirrors and partly as microshutters.

[0042] In Fig. 2 is an exemplary switching state of the embodiment of the Fig. 1. In this diagram, all microelements 1 in fields 10a and in a section of 10b are in a light-permeable, open position, while the microelements 1 in the remaining fields of 10b are all closed. The closed state of the microelements 1 is generated by an applied and sufficiently large electrical voltage between the microelements 1 and the base plate segments (not shown here) arranged underneath. The open microelements 1 are not subject to electrostatic attraction. The leaf sections of the open microelements 1 are pivoted by approximately 90° relative to the closed position, so that the local transmittance is maximized.

[0043] Fig. Figure 3 shows a schematic exploded view of the fields 10a-10e along with their electrical leads 32 and the base plate 2 of the first embodiment. The base plate 2 comprises the non-conductive insulation layer 22 and the base layer 21, which is electrically divided into the base plate segments 2a-2c. Both the base layer 21 and the insulation layer 22 are made of an optically transparent material. Applying an electrical voltage between the base plate segments 2a-2c and the fields 10a-10e creates an electrostatic force directed toward closing the microelements. The enlarged partial view of the lead architecture of the fields 10a-10e shows the leads 32, which are electrically insulated from each other and from the non-addressed fields.

[0044] Fig. Figure 4 shows a schematic representation of the first exemplary embodiment of the mirror shutter system 100 according to the invention, which has the above-described structure with the fields 10a-10e and with a layer structure and a segmentation of the base plate 2. The actuating means 3 further comprise the controllable voltage source 31, which here, for example, has eight channels for individually contacting the three base plate segments 2a-2c of the bottom layer 21 and the five fields 10a-10e, as well as, for example, a microcontroller, driver, and switch. An exemplary switching state is shown in which the ring-shaped area of ​​the field 10b, shown in black, is closed, i.e., a corresponding electrical voltage is applied between the field 10b and the base plate segment 2a. With this configuration, the Fig. 2 shows the switching state as a section of the mirror shutter system 100.

[0045] Fig. Figure 5 shows exemplary switching states of the first embodiment, with the geometric figures shown corresponding to the closed, i.e., opaque, sections of the respective arrays of microelements. The bottom sub-image also shows a vertical plan view of arrays 10a-10e and the baseplate segments 2a-2c arranged beneath them (outlined by dashed lines), which clearly shows the overlap between arrays 10a-10e and baseplate segments 2a-2c, which is relevant for the actuation of the microelements. The electrostatic actuation is directed toward closing the microelements; accordingly, the microelements assume the open position in their electrically voltage-free state.For example, the switching state shown in partial image (a), in which all microelements of field 10e are closed and all other fields (not shown) are open, is realized by applying a voltage sufficient to completely close the microelements between field 10e and all three baseplate segments 2a-2c, while the remaining fields are at the same electrical potential as the baseplate segments. In the switching state of partial image (b), in which only the microelements in two opposite sections of field 10d are closed, an electrical voltage is applied between field 10d and baseplate segments 2a and 2c, whereas baseplate segment 2b is at the same electrical potential as field 10d, so that the microelements in the overlap area of ​​field 10d with baseplate segment 2b are in their open position.The switching state of partial image (h) is obtained by applying an electrical voltage between the fields 10a and 10b and the base plate segments 2b. Other exemplary switching states are shown in the remaining partial images, with a multitude of further switching states being feasible with the present embodiment of the mirror shutter system according to the invention.

[0046] Fig. Figure 6 shows a plan view of the microelements 1 of a second embodiment of a mirror shutter system according to the invention, with all microelements 1 in the closed position. The geometry and arrangement of the microelements 1 are similar to the first embodiment. However, the difference is that between some of the microelements 1, the webs 14 are applied to the base plate located beneath the microelements 1. In the illustration of Fig. 6, the webs 14 are shown as contour lines of the respective microelements 1 with a larger line width. The webs 14 can, for example, be in the form of a widened fastening section 11 and / or as a border of the leaf sections 12 (in the closed position). The webs 14 are, for example, opaque. In the open positions of the microelements 1, the presence of such webs 14 does indeed reduce the global transmittance of the mirror-shutter system. However, the webs 14 represent a further degree of freedom for the inventive reduction of the degree of order of the grating formed by the entirety of the microelements 1 and can contribute to a further homogenization of the transmitted light impression. In addition to the number and orientation of the webs 14, their width can also be varied with further advantage.

[0047] Fig. Figure 7 shows a plan view of a portion of the microelements 1 of a third embodiment of a mirror shutter system according to the invention, with all microelements 1 being in an open position, in which the leaf sections of the microelements 1 protrude perpendicularly from the plane of the drawing. The ring-like fields known from the first embodiment appear nine times in the image section and are each differently shaped and arranged at irregular intervals from one another, with the spaces between them also being filled with polygonally contoured microelements 1. The entirety of the microelements 1 forms an unstructured grid.

[0048] In Fig. Figure 8 shows an exemplary switching state of a fourth embodiment of a mirror shutter system according to the invention. In this diagram, all microelements 1 in fields 10a and 10c are in a light-transmitting open position, while the microelements 1 in the remaining fields 10b, 10d, and 10e are all closed. The closed state of the microelements 1 is generated by an applied and sufficiently large electrical voltage between the microelements 1 and the base plate segments (not shown here) arranged underneath. The open microelements 1 are not subject to electrostatic attraction. The leaf sections 12 of the open microelements 1 are pivoted approximately 90° relative to the closed position, so that the local transmittance is maximized.

[0049] Fig. 9 shows a plan view of a portion of the microelements 1 in the closed position of a fifth exemplary embodiment of a mirror shutter system according to the invention. The microelements 1 each have a contour consisting of partially curved lines. Only the fastening sections 11 are each formed as rectilinear, while the blade sections 12 otherwise have a curved contour. The use of curved contours and / or their combination with rectilinear sections represents a further advantageous possibility for reducing the regularity of the grid formed by the entirety of the microelements 1. The fastening sections 11 are deliberately oriented differently here, and the microelements 1 are formed differently from one another and asymmetrically.

[0050] Fig. Figure 10 shows a cross-sectional partial view of the mirror shutter system according to the invention. The illustration includes the base plate 2 and a single microelement 1, which are accommodated between two transparent cover plates 4. The microelement 1 forms an electrode and is made of an electrically conductive material for this purpose. The base plate 2 comprises, in a layered structure, the translucent and electrically conductive base layer 21 and the translucent and electrically insulating insulation layer 22 arranged thereon. The microelement 1 is arranged with its fastening section 11 on the insulation layer 22, and the pivoting movement of the blade section 12, which is characterized by two essentially plane-parallel surfaces, takes place via a curvature of its hinge section 13. In the Fig. In the state shown in Figure 10, an electrical voltage is applied between the microelement 1 and the base layer 21 by the voltage source 31 via the leads 32, so that an electrostatic attraction between the base layer 21 and the microelement 1 leads to the latter closing into the illustrated horizontal, i.e. closed, position of the blade section 12. Two open positions of the microelement 1 are shown in dashed lines, namely the maximum open position oriented essentially orthogonally to the base plate 2, which corresponds to maximum transmission, and a half-open intermediate position in which an angle of approximately 45° exists between the blade section 12 and the base plate 2.The maximum open position is assumed when microelement 1 and base layer 21 are at the same electrical potential, and in the partially open intermediate position, a lower electrical voltage is applied compared to the closed position. By appropriately varying the applied electrical voltage, a variety of partially open intermediate positions with different angles of the blade section 12 relative to the base plate 2 can be achieved.

[0051] Fig.Figure 11 shows a detailed cross-section around the hinge section 13 of the microelement 1. This shows the layer structure of the microelement 1, which has a compressively stressed layer 1a arranged at the bottom and a tensile-stressed layer 1b. The effect of these residual stresses consists in the illustrated curvature of the microelement 1 along its hinge section 13 by the roll-up angle w. Along the fastening section 11, this curvature is prevented by the positive connection to the base plate 2, and along the blade section 12, the compressively stressed compensation layer 1c ensures that the global, i.e., effectively effective, residual stress in the blade section 12 disappears, thus preventing any curvature there. The size of the roll-up angle w can be influenced in particular by the width of the hinge section 13.A variation in the width of the hinge sections 13 among the microelements 1 constituting the mirror shutter system consequently leads to a variation of the roll-up angle w in each open position of the microelements 1, whereby the formation of disturbing ghost images in the reflected light impression can be avoided.

[0052] The invention is not limited in its implementation to the preferred embodiment described above. Rather, a number of variants are conceivable, which utilize the presented solution even in fundamentally different embodiments. All features and / or advantages apparent from the claims, the description, or the drawings, including structural details or spatial arrangements, may be essential to the invention both individually and in a wide variety of combinations. List of reference symbols: 100 mirror shutter system 10a-e fields 1 microelement 1a compressive strained layer 1b tensile stressed layer 1c compensation layer 11 Fastening section 12 sheet sections 13 Hinge section 14 jetty 2 base plate 2a-c base plate segment 21 Soil layer 22 Insulation layer 3 Actuating means 31 Voltage source 32 supply line 4 cover plate w Roll-up angle

Claims

[1] A mirror shutter system (100) comprising a plurality of microelements (1) configured as micromirrors and / or as microshutters, wherein each microelement (1) has an opaque sheet-like body which is hingedly mounted on a translucent base plate (2) of the mirror shutter system (100) by means of an edge-side fastening section (11), such that each microelement (1) is pivotable between an opaque closed position and at least one translucent open position, wherein the microelements (1) each have a layer structure comprising at least one compressively stressed layer (1a) and one tensile-stressed layer (1b), wherein a compressively stressed compensation layer (1c) is arranged on the tensile-stressed layer (1b) along a sheet section (12) of each microelement (1), such that each microelement (1) is divided into the following sections: - the blade section (12), which is globally stress-free and has two essentially plane-parallel surfaces, - the edge-side fastening section (11), which is rigidly arranged on the base plate (2) of the mirror shutter system (100), and - an intermediate hinge section (13) which has a residual stress-induced curvature, whereby an open position of the microelement (1) is formed, wherein the totality of the microelements (1) forms an irregular or unstructured lattice in the respective closed position. [2] Mirror shutter system (100) according to claim 1, characterized by that the microelements (1) each have an irregular polygonal contour in the closed position. [3] Mirror shutter system (100) according to claim 2, characterized by that the number of sides of the polygonal contours of the microelements (1) is between 3 and 8. [4] Mirror shutter system (100) according to claim 1, characterized by that the microelements (1) in the closed position each have a contour of at least partially curved lines. [5] Mirror shutter system (100) according to one of the preceding claims, characterized by that the mirror shutter system (100) has actuating means (3) for pivoting the microelements (1) between the at least one open position and the closed position, wherein individual microelements (1) and / or groups of microelements (1) can be actuated by means of the actuating means (3). [6] Mirror shutter system (100) according to claim 5, characterized by that the entirety of the microelements (1) forms a circular or elliptical or polygonal shape or a free form, wherein ring-segment-shaped groups of microelements (1) can be actuated by means of the actuating means (3). [7] Mirror shutter system (100) according to claim 5 or 6, characterized by that the actuating means (3) constitute an electrostatic operating principle, for which purpose the base plate (2) of the mirror shutter system (100) comprises an electrically conductive material and the microelements (1) comprise or form electrodes, wherein the actuating means (3) comprise a controllable voltage source (31) for applying electrical voltage signals between the base plate (2) and the electrodes. [8] Mirror shutter system (100) according to claim 7, characterized by that the base plate (2) has a plurality of mutually electrically insulated base plate segments (2a, 2b, 2c) and the electrodes are electrically connected together to form a plurality of mutually electrically insulated fields (10a, 10b, 10c, 10d, 10e), wherein the base plate segments (2a, 2b, 2c) and the fields (10a, 10b, 10c, 10d, 10e) are each individually electrically connected to the voltage source (31). [9] Mirror shutter system (100) according to one of the preceding claims, characterized by that the hinge section (11b) has a radius of curvature which is one hundredth to one third of the length of the longest side of the contour of the respective microelement (1). [10] Mirror shutter system (100) according to one of the preceding claims, characterized by that the blade section (12) is aligned substantially orthogonally to the base plate (2) in a maximum open position of the respective microelement (1). [11] Mirror shutter system (100) according to one of the preceding claims, characterized by that the width of the hinge sections (13) of different microelements (1) varies, so that a rolling angle (w) of the hinge sections (13) varies in the at least one open position of the microelements (1). [12] Mirror shutter system (100) according to one of the preceding claims, characterized bythat the layer structure of each microelement (1) has at least one electrically conductive layer, whereby the electrode is formed in each case. [13] Mirror shutter system (100) according to one of the preceding claims, characterized by that the base plate (2) has a layer structure which comprises a translucent, electrically conductive base layer (21) and a translucent, electrically insulating insulation layer (22), wherein the fastening section (12) of each microelement (1) is arranged on the insulation layer (22). [14] Mirror shutter system (100) according to one of the preceding claims, characterized by that the sides of the contours of the microelements (1) have a length of 1 micrometer to 2 millimeters.

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