DE102009028626A1 - Light modulation device for a display for representing two- or three-dimensional image content or image sequences, comprises light modulator and controller, where diffracting unit is arranged downstream of light modulator - Google Patents

Abstract

The light modulation device (10) comprises a light modulator (12) and a controller (14). A diffracting unit (20) is arranged downstream of the light modulator in the direction of propagation of a light wave field (16). The diffracting unit has a variable diffracting structure, by which the light wave field, varied by the light modulator, is diffracted in a variable and predeterminable manner. An independent claim is also included for a method for manufacturing a light modulation device.

Description

The The invention relates to a light modulation device for a display for displaying two- and / or three-dimensional image content or picture sequences. The light modulation device has a Light modulator and a control device. The phase and / or the amplitude of a substantially collimated lightwave field is with the light modulator depending on the location changeable to the light modulator. The light modulator is controllable with the control device. Furthermore, the concerns The present invention relates to a display and a method of manufacture a light modulation device.

Known Holographic displays are a light modulator (Spatial Light Modulator, SLM) with a matrix-like arrangement of Contain pixels. These may, for example, be light modulators which phase or amplitude or phase and the amplitude - d. H. complex valued - the with change or modulate the SLM of interacting light can.

By way of example only, an auto stereo display (ASD) according to the WO 2005/060270 A1 in which the current eye position of at least one observer is detected and the stereoscopic images are deflected in the direction of the left and right eye of the observer depending on the current eye position. This is achieved by means of a "backplane-skuttering" device. With respect to a holographic display, for example, the WO 2006/066919 A1 or the WO 2006/027228 A1 pointed. In a Fourier plane of such a holographic display higher diffraction orders arise. The spacing of these diffraction orders is proportional to the reciprocal of the pixel pitch of the SLM of the display, ie, the center-to-center spacing of the periodic light modulator structures. For holographic displays with a viewer window, a diffraction order must at least be the size of this viewer window. The pixel pitch of the SLM must therefore be selected according to the desired size of the observer window. As a rule, the viewer window must be only slightly larger than the diameter of an eye pupil, resulting in a relatively large pixel pitch of the SLM. A typical value would be 30 μm to 50 μm.

However, a holographic reconstruction is only visible when the viewer positions an eye on the viewer window. Either the viewer must therefore assume a fixed position or the observer window must follow the current eye position of the observer (tracking). For this purpose, a detection of the eye position and an arrangement for observer tracking are needed. Known arrangements for observer tracking, such as in the WO 2006/119920 A1 described light source tracking or as for example in the WO 2008/142108 A1 described electrowetting tracking, are structurally complex.

Known is also a field lens function to realize, either separately present or integrated in the tracking arrangement. Through this field lens function will light from different positions of the display to a specific one Focused position in a viewer plane. Z tracking, d. H. the tracking of the viewer window in the axial direction of the display (when moving the observer's eyes to the display or when moving away the viewer's eyes away from the display), requires for example, a variable field lens function.

On the other hand, the possibility of software or coding tracking is known, such as in the WO 2006/066906 A1 described. This encodes linear phase traces in the SLM pixels, optionally in addition to a hologram. The angle range within which a coding track can be used meaningfully, however, is also limited by the pitch of the SLM. In principle, although the tracking range may be several orders of diffraction in an encoding track, the intensity of the tracking viewer window would decrease in accordance with the intensity in the higher diffraction orders. As a rule, it would therefore make sense to have two or three diffraction orders, or at most only two, as the area for tracking the observers.

in principle It would also be possible to have a SLM with a smaller one To use pixel pitch. A sensible range of motion of a viewer in front of a holographic display but includes an angle of some Degree. For this purpose, a pitch in the area would be less Micrometers are needed. A 24 inch display with one Pitch of for example 2 microns would have for example about 40 billion pixels result in what Production, control and computer calculation of hologram data would not be feasible in real time.

Of the The present invention is therefore based on the object, a light modulation device, a display and a method for producing a light modulation device specify and further develop the type mentioned by which the above problems are overcome. Especially should be an easy-to-implement tracking the viewer window the holographic display or a tracking of the sweet Spots of an autostereoscopic display or beam deflection for multi-view displays.

In terms of The light modulation device is the object of the invention solved the teaching of claim 1. Further advantageous embodiments and further developments of the invention will become apparent from the dependent claims out.

According to the invention a light modulation device of the type mentioned by characterized in that in the propagation direction of the light wave field at least one diffraction device downstream of the light modulator is. The diffraction device has a variable diffraction structure on. With the diffraction structure this is changed by the light modulator Light wave field changeable deflectable in a predeterminable manner.

According to the invention, it has first been recognized that tracking of at least one observer window can be realized, in particular, by arranging a diffraction device, which has a variable diffraction structure, downstream of the light modulator in the propagation direction of the lightwave field. This can be used to change the diffraction structure of the diffraction device depending on the current eye position of a viewer such that the diffraction device generates prescribable higher diffraction orders of the light wave field influenced by the light modulator or deflects the light rays in the direction of the current eye position of a viewer by diffraction. In the individual diffraction orders, periodic repetitions of the light wave field influenced by the light modulator arise. The diffraction structure of the diffraction device is to be set or controlled by a control device such that a repetition of the light wave field influenced by the light modulator or of the observer window also arises at the current eye position of a viewer of the display. This allows the viewer to write the information written in the light modulator to the WO 2006/066919 A1 visually perceive the principles described.

in principle could the diffraction structure of the diffraction device a have any periodic structure. Here is in particular a two-dimensional lattice structure conceivable. Preferred is as Diffraction structure of the diffraction device a one-dimensional lattice structure or a sawtooth structure. So could an im Essentially vertical one-dimensional linear lattice structure be realized in the diffraction device to one in horizontal Direction diffracted periodic repetition or diffraction orders to create. Since the diffraction device is also suitable, to change the phase of the light wave field and here could distract individual parts of the light wave field locally the diffraction device may also be referred to as a phase deflector. Basically, in the diffraction device a one-dimensional linear lattice structure can be realized which has a predetermined angle relative to the horizontal.

The Diffraction structure of the diffraction device should be a grating period or have a periodic distance or course, which essentially of the order of the wavelength of the used light is located. In that regard, basically come Grating periods, which may be in an area, which can range from 200 nm to 30 μm. in this respect the effect of the diffraction device is not exclusively the a diffraction of the diffraction device passing through the light. Especially if the grating periods are in a range of greater when, for example, 10 μm, the mode of action is the diffraction device is that of an element which represents the phase of the Light changed. Accordingly, the following is the Diffraction device to understand in this context.

Prefers two diffractive devices are provided, of which one diffracting device only a vertical deflection and the other diffraction device only realized a horizontal deflection. These two diffraction devices are in analogy to a phase SLM as pixelated elements with a controllable phase modulation in many stages between 0 and about 2π of the wavelength used of the light, however, so that only a strip-shaped or only a columnar arrangement of pixels is present.

In a dimension or direction (horizontal or vertical) can be a very fine structuring can be set, making a smaller one Pixel pitch (or a small grid period) for a large one Angular range of viewer tracking can be realized can. Lie in the other dimension (vertical or horizontal) continuous pixels essentially over the entire Height or width of the diffraction device (which also the Implement the function of a phase deflector or a phased array can).

Of the Pixel pitch in the fine-structured direction is determined according to used wavelengths of lighting and for these wavelengths are chosen desired angular range.

For displays that require only a horizontal viewer tracking, for example, it is possible to use even a diffraction device. In addition, in general, the combination of diffraction devices with other means for observer tracking is possible, either to increase the tracking angle or horizontal and / or vertical deflection by un realize different methods.

The Terms horizontal and vertical are particular in this context generalized so as to understand that it is approximately perpendicular to two to each other arranged directions. In principle, could the entire tracking arrangement also be rotated, for example such that one tracking direction is +45 degrees diagonal and the other Tracking direction is -45 degrees diagonal.

in principle can for diffraction devices all the principles of operation which are also used for phase light modulators are known. In the embodiments, hereinafter, a Diffraction device described which on phase modulation means Liquid crystals based.

by virtue of the fine structuring is only in one dimension or direction Advantageously, the production and control of the diffraction device far less complex than, for example, in matrix form arranged liquid cells (an electrowetting cell array) the case may be. For example, there would be a diffraction device for realizing a diffraction in the horizontal direction for a display with a screen diagonal of 24 inches and a minimum grating structure / grating period of 2 μm only 265,000 Pixel; a diffraction device for realizing a diffraction in vertical direction only 150000 pixels. The number of pixels is in this fair smaller than a horizontally and vertically pixelated Light modulator with VGA resolution.

One binary grid with invariable diffraction structure - for example a polarization grating - has a largely invariable Grid period and thus realizes a substantially unchanging Deflection angle. With the variably controllable diffraction device however, with a plurality or a series of in the form of Phase stages formed diffraction structures in the diffraction device are writable by varying the quantization (ie the Number) of the phase levels and / or the slope of the linear phase curves the deflection or diffraction angle of the diffraction device passing through Light can be set variably in very fine steps / steps.

So could initially be a continuous linear increasing or declining phase progression that is specific to a particular corresponds to positive or negative deflection angle. Then the Phase values for the position of each pixel of the diffraction structure modulo 2π calculated. It becomes the representable phase level (Quantization) with the smallest difference to that calculated Value inscribed in the respective pixel of the diffraction structure. By calculating modulo 2π is automatically a continuous Phase characteristic of the light wavefront guaranteed.

The calculation of the phase values for the diffraction device can also be considered in analogy to a blazed grating:
Deflection angles are determined from the lateral nominal position of the observer window and its distance from the display in order to deflect light from a position on the display or light modulator towards the observer window.

A blazed grating is calculated whose grating period corresponds to the desired deflection angle, according to the general grating equation: sin α ± sinβ = mλ / g

there α is the angle of the incident light, β the Angle of the light deflected by the grid. m is the diffraction order. For a blaze grating, m = 1 · λ is usually the wavelength of the light used and g the lattice constant of the Blaze grid. The plus sign on the left side of the equation is to be applied when the incident beam and the diffracted beam Light beam are on the same side of the Einfallslosts. The reverse is true for the minus sign too.

This blazed grating is scanned with the sample points spaced from the pixel pitch of the diffraction device and the resulting samples written to the diffraction device. According to the sampling theorem, the blaze grating can be scanned correctly if the grating period g is at least twice the pixel pitch of the diffraction device. g ≥ 2p p denotes the pixel pitch of the diffraction device.

is If this condition is met, then in principle any Grating periods of the Blaze grating can be realized. Therefore, too finely graduated adjustable deflection possible (ie small tracking vessels), up to a maximum angle that the Blaze grating with a grating period twice the pixel pitch corresponds to the diffraction device.

An ideal Blaze grating directs all light into its 1st order. Ideally, higher orders would not result from the blaze grating itself, but only from its scanning with the pixel pitch of the diffraction device. By a non-ideal behavior, however, can also more Blaze orders arise, see, for example, the following remarks on temperature compensation.

in principle can have higher orders of the diffraction device used to increase the tracking range. This is possible in particular for a single viewer system. A higher order of the diffraction device would correspond the use of grating periods of the Blaze grating that are smaller as twice the pixel pitch of the diffraction device. In spite of The violation of the scanning theorem becomes a part of the light in one higher order of the diffraction device to the desired Steered position. In addition, but then creates a in usually brighter repetition of the viewer window even in the 0th order of the diffraction device. For sufficiently small Pitch the diffraction device, these orders are further apart as the eye relief and would be a single viewer do not bother.

Conversely, higher orders of the diffraction device can be reduced or suppressed by various methods, in particular in applications in which they are disturbing. Here, for example, the use of methods such as Pixelapodisation is conceivable, such. B. in the date of this application not yet published DE 10 2008 002 692.1 or PCT / EP2009 / 050476 described.

The Suppression of higher orders is particular needed for a multi-viewer system, if higher Orders that arise when tracking a single viewer, would disturb another viewer.

Preferably becomes a light modulator with two separate diffraction devices combined. In the light modulator, a hologram is encoded, wherein the light modulator has a relatively coarse pixel pitch (eg 30 μm × 30 μm) and a horizontal / vertical matrix of pixels. The one Diffraction device is for a horizontal and the other diffraction device is intended for vertical viewer tracking. Each of the two diffraction devices has a fine pitch (eg 1 μm), but is only structured in one dimension. The range of motion of the viewer is then about as big as you would with a much more complex system with a single light modulator with a pixel pitch of for example 1 μm × 1 μm and 160 billion pixels and design with coding tracking.

Farther could consider a field lens function by consideration corresponding phase terms and possibly Prismenterme at least partially be varied driven in the diffraction device. The field lens function corresponds to a local in different lateral positions on the Display or the light modulator different deflection angle. In other words, here would be no periodic structure are written in the diffraction device, which via the entire effective area of the diffraction device a having a substantially constant grating period. This is rather provided over the entire effective area of the Diffraction device a lattice structure or a diffraction structure inscribe which over the entire effective area the diffraction device a variable grating period or diffraction structure, so that hereby a field lens function is feasible. The pixel pitch of the diffraction device must then but be chosen so small that even the maximum necessary Deflection angle from the opposite light modulator or Display edge to the viewer still within the used diffraction order lies.

In an advantageous embodiment, the display additionally one in their optical property not changeable Field lens on. This field lens focuses on an average observer distance and a middle lateral viewer position. This can optionally refractive or diffractive, the latter for example by a corresponding dimensioned and arranged Bragg grating can be realized. In the latter case, the diffraction device in the beam path is preferred arranged after the Bragg grating, since this has a fixed angle of incidence needed. In the first case, the refractive lens can optionally be arranged before or after the diffraction device.

A Tracking a viewer window in the direction along the optical axis or in a direction perpendicular to the surface of the light modulator (Z-tracking) could by registered Phase terms representing auxiliary lenses in the light modulator and / or into the at least one diffraction device. A Compensation of aberrations of a field lens provided in the display could then be in the at least one diffraction device and done in the light modulator by coding. In this case, enough a larger one for a particular tracking angle range Pixel pitch of the diffraction device than when integrating the entire field lens function in the diffractive device and the light modulator needed would.

It should be noted in both cases that, in contrast to a pure deflection (prism), a spherical lens function (for example the phase terms for the entire field lens or for the additional lens for Z-tracking) or an aberration correction may not be completely independent of horizontal and vertical phase profiles can be disassembled. In the case of the lens function, this clearly corresponds to the difference between a single spherical lens and two crossed cylindrical lenses. The phase curves of the cylindrical lenses and the spherical lens would only coincide in the paraxial approximation, ie for a small aperture of the lenses. They differ for larger lenses. This means that the required horizontal phase curve on the display to deflect light to a particular observer position, for example at the top of the display can be different than in the middle or bottom and that the required vertical phase course, for example, left on the display to be different can be considered in the middle or right. On the other hand, it may not be possible to display the entire phase curve with the SLM alone because the sensibly codable local gradient of the phase curve is proportional to the reciprocal of the pixel pitch and the SLM generally has a comparatively large pixel pitch.

The phase curve φ (x, y) which represents the lens function or aberration correction is then advantageously decomposed in the following way: φ (x, y) = φ ₁ (x) + φ ₂ (y) + φ ₃ (x, y) where φ ₁ (x) is a phase function which depends only on the horizontal coordinate, φ ₂ (y) a phase function which depends only on the vertical coordinate. These components φ ₁ (x) and φ ₂ (y) are compensated or coded in the diffraction device for horizontal or vertical diffraction and the smaller component φ ₃ (x, y) in the light modulator.

In a preferred overall design of a holographic display, the latter has an illumination device which has an optical waveguide, from which the light running in the optical waveguide is evanescently coupled out by means of a volume grating located thereon. Such a lighting device is for example in the DE 10 2009 027 093.0 described. As a result, a substantially collimated light wave field is generated with a predeterminable polarization state. Such a lighting device can advantageously be made very flat. The illumination device is in this case designed and arranged such that the collimated light wave field propagates in the direction of the light modulator. The light modulator could be designed such that it modulates the light of the light wave field in a transmissive or in a reflective manner. Furthermore, downstream of the light modulator in the direction of propagation of the light wave field is a component which realizes a field lens function, for example a Bragg grating.

Especially The illumination device is preferably between the light modulator and the diffraction device arranged. This lighting device can be called a frontlight in this case. If one Component is provided which realizes a field lens function, is the lighting device between the light modulator and arranged the component implementing the field lens function. Of the Light modulator is reflective in this embodiment working light modulator, which is the phase of the with him interacting light. Between the lighting device and the light modulator is a λ / 4 plate or the like arranged optical component, so that the polarization state of the from the illumination device coupled out light once at Propagating in the direction of the light modulator is rotated 45 degrees and after reflection on the light modulator and again through the λ / 4 plate or by the optical component by more 45 degrees is turned. Accordingly, this is in the direction of the illumination device propagating light relative to that from the illumination device decoupled light turned by a total of 90 degrees, so that the am Light modulator relfektierte light the lighting device - and in particular their volume grid - essentially undisturbed can go through. The lighting device or the field lens function realizing component is the first diffraction device downstream, which diffracts the light in a horizontal or vertical direction realized. The first diffraction device is the second diffraction device subordinate to which a diffraction of the light into a vertical or realized horizontal direction.

Naturally can also be designed in the form of a backlight lighting device used, the essentially collimated lightwave field provide. The backlight are then in the propagation direction of the light wave field, a transmissive light modulator and the two diffraction devices arranged downstream. A field lens function realizing component could between the lighting device and the light modulator or between the light modulator and a Be diffraction arranged. In principle, a diffraction device also in a car stereo display or in a conventional one 2D display are used, in which the displayed image content for safety reasons only in the direction of the viewer's eyes to distract or to focus. Prerequisite for this is that this display is a coherent or partially coherent Lighting has.

It may be necessary to correct temperature variations in the diffraction device. Due to the development of heat in the electronics and the illumination device, displays often have a temperature gradient from the center to the edge. With the Tempe For example, the birefringence of the LC material decreases (LC = Liquid Crystals). In addition, the elastic constants of the LC material also change, which has an influence on the orientation of the LC material under a given tension. As a result, a temperature change can influence the phase modulation or the diffraction behavior of the diffraction device.

While one with a horizontally and vertically pixelated light modulator principle would have the opportunity through different Controlling the individual pixels to compensate for this temperature gradient, is this in a columnar or linear structure Modulator or in a column or line constructed Diffraction device is not the case. So there is a tendency the danger that, for example, in a controlled, vertical aligned column the center of the column another phase modulation causes as the top or bottom of the column. This effect is not wanted.

A too small birefringence of the LC material would have for example As a result, the actual phase becomes proportional reduced to the target phase. This would be equivalent among other things to a blaze lattice of wrong height, so the 2π jumps not more votes. This would make higher blaze orders generated.

created by a temperature gradient a false deflection angle, so can this within a diffraction order of the light modulator by a compensated for additional linear phase curve in the light modulator become. But preferred is a device that the occurrence avoids a temperature gradient by the diffraction device or the entire display is actively temperature controlled. in this respect So could a temperature correction by a corresponding Coding in the light modulator and / or by controlling the temperature the diffraction device (for example by Peltier effect) respectively.

at Using a field lens in the beam path in front of the diffraction device traversed by the light, this causes light can enter obliquely into the diffraction device, or that the entrance angle into the diffraction device spatially varied. For a field lens with constant optical properties On the other hand, this angle of incidence is known and constant over time. This can be used for compensation.

is based the phase modulation in the diffraction device on a birefringent Material, so it should be noted that for an oblique Passage changes the effective birefringence. At the same Thickness of the phase modulator or the diffraction device would So an obliquely incident light beam another phase modulation experienced as a vertically incident light beam. A change the phase modulation by activation is only possible to a limited extent. In a line-shaped diffraction device For example, you can change the angle of incidence from left to right not readily via a drive voltage compensate.

Possible however, is a definable and unchangeable thickness variation in the phase modulating layer. So would for a line-shaped diffraction device the thickness of the LC layer from the middle to at least the left and right edge slightly increase or decrease, typically around 10 percent at 20 degrees oblique incidence of light. If two crossed diffraction devices are arranged one after the other, However, there is also a variable oblique idea the light from the first to the second diffraction device. In the rule becomes larger in the horizontal direction Tracking area needed as in the vertical direction. It So is advantageous, the diffraction device for the vertical Direction in the beam path to arrange first, because then the impact angle on the following diffraction device for the horizontal Direction are smaller than in the reverse arrangement.

To the oblique incidence of light on the diffraction device is following executed: in deflection could the angle of incidence also by the drive voltage of the diffraction device be compensated. In such a light incidence it can in principle to a crosstalk of a light beam to a neighboring pixel the diffraction device come. Crosstalk can be reduced be reduced by the layer thickness of the LC, for example by using materials with high birefringence. At known oblique angle, this can be done in principle by structured Electrodes on both substrates and / or a staggered arrangement compensated by electrodes on both substrates of the diffraction device become.

Farther could be a compensation of an oblique passage by the diffraction device due to the possibly provided component to realize the field lens function by the fact that the Thickness of the LC layer of the diffraction device adapted accordingly is or that both substrates of the diffraction device accordingly having staggered electrodes. This is therefore possible because the component, which realizes the field lens, at each location of the Component a predetermined and therefore known angular deflection of the the component has passing light. In that regard, the angle of incidence for a predeterminable position on the diffraction device known.

In terms of the control of the diffraction device should be noted the following: usually there it in a TFT display one transistor per pixel, which is also in the pixel is housed. At a small pixel pitch, as in the case of Diffraction device in the order of 2 microns can be provided, the transistors are usually wider as the individual rows or columns. With the help of a staggered Fanning at the edges of the display can the driving circuits by means of TFT (Thin Film Transistor) be accommodated on the substrate. Alternatively you can on the substrate Circuits in CoG technology (Chip on Glass) be applied to drive the electrodes.

According to one preferred embodiment is the diffraction device designed such that with the diffraction device a predetermined grid-shaped diffraction structure adjustable or inscribable is, which extends only in one direction. With others Words are in the inscribed in the diffraction device Diffraction structure around only a linear lattice structure. These Lattice structure can be binary or discrete or continuous Have gradients or sections of mixed forms thereof.

Prefers the diffraction device is designed such that the with the Diffraction device adjustable diffraction structure in the periodicity changeable is.

In In terms of design, the diffraction device could be used in the Essentially linear and substantially parallel to each other arranged electrodes which on a first substrate are arranged. The electrodes could thus be strip-shaped be educated. The diffraction device could be a second Substrate which is spaced from the first substrate is arranged. The second substrate could be a sheet-like Electrode or a plurality of substantially linearly formed and im Have substantially parallel to each other arranged electrodes. If the second substrate is a plurality of substantially linearly formed and having electrodes arranged substantially parallel to one another, could these electrodes to the linear electrodes of the substantially opposite or first substrate be arranged with a predetermined lateral offset. The alignment the electrodes of both substrates would be substantially parallel.

Thus, with the electrodes of the light modulation device, an electric field distribution can be realized, with which, for example, essentially a sawtooth curve - comparable to the representation of 3 - Can be generated with a nearly vertical sloping edge, at least one intermediate electrode layer is provided in a preferred embodiment between two substrates. The intermediate electrode layer has electrodes. Depending on the specific configuration of the intermediate electrode layer, electrodes could be arranged on at least one surface of the intermediate electrode layer. Particularly preferably, four intermediate electrode layers are provided between two substrates. The at least one intermediate electrode layer is preferably aligned parallel to a surface of a substrate. Both the electrodes provided on the substrates and the electrodes of the intermediate electrode layer can be electrically controlled individually in order to be able to realize a predetermined electrical potential curve as accurately as possible to a predetermined or desired ideal potential profile between the two substrates.

Comparable to the arrangement of arranged on the at least one substrate Electrodes are preferably the electrodes of the intermediate electrode layer formed substantially linearly, substantially parallel to each other and aligned in a predeterminable direction. This could be the electrodes of the interelectrode layer have a grating period which substantially corresponds to the grating period of a substrate arranged electrodes corresponds.

In a preferred embodiment, the distance between a substrate and an adjacent intermediate electrode layer and / or between two adjacent intermediate electrode layers predetermined. This distance could be a fraction of the distance two adjacent electrodes or a fraction of the grating period the electrodes of the substrate or the interelectrode layer correspond. For example, the width of the electrodes transverse to the longitudinal direction of the electrodes 1 micron, the Distance between two adjacent electrodes 1 micron, the Distance between the first substrate and the intermediate electrode layer adjacent thereto 0.5 μm, the distance between the interelectrode layer and the intermediate electrode layer adjacent thereto also 0.5 μm be. In that regard, in this example, the distance between a Substrate and an adjacent intermediate electrode layer or between two adjacent intermediate electrode layers smaller than the distance between two adjacent electrodes, namely, it corresponds half of that value and could be even smaller be.

In principle, the electrodes of the first and / or second substrate and / or of an intermediate electrode layer which are formed linearly and arranged parallel to one another could be aligned in a predeterminable direction. In this case, the linearly formed and mutually parallel electrodes of the first and / or second Subst rats and / or an intermediate electrode layer may be aligned substantially parallel to each other. For this purpose, it must be ensured in the production of the light modulation device according to the invention that the electrodes arranged in the different layers or on the substrates are each aligned parallel to one another.

The Electrodes of the first and / or second substrate are for the light used formed transparent. The first and / or the second substrate is transparent to the light used educated. The refractive index of the electrodes preferably corresponds essentially the refractive index of the substrate. In other words For example, the electrode material and the substrate material are selected or are designed such that they are essentially the same Have refractive index. This is especially for the Light of the wavelengths used.

Between the first and second substrates and / or between a substrate and a thereto adjacent intermediate electrode layer and / or between two adjacent intermediate electrode layers is according to a preferred embodiment, a material arranged with which local changes in refractive index for at least a polarization direction of the light by adjusting a Material influencing tax variable achievable is. In the case of the material influencing control variable It could be electrical or electrical Act electricity, causing the individual elements of the material itself change accordingly in their orientation and / or in their optical property. So the material could be liquid crystals or a Polymer layer - in particular a polyimide - with Liquid crystals or elongated Have nano-particles. In particular, the nano-particles could be metallic Carbon nanotubes (Carbo Nano Tubes) or nano-particles having a permanent electrical dipole distribution. It could also be used nano-particles, which have a belibige shape, which for the used Light birefringent are configured and which by, for example an electric field in its spatial orientation align.

If the light modulation device at least one intermediate electrode layer has, the material could be a relatively stable and suitably formed polymer layer with liquid crystals or with elongated nano-particles in intervals the polymer layer on which in the production directly the electrodes of the intermediate electrode layer are applied. Optionally, the polymer layer with a thin Protective layer to be coated before the electrodes of the inter-electrode layer can be applied to this protective layer to prevent the electrically conductive material, which is the electrodes the intermediate electrode layer forms enters the polymer layer. Alternatively, the material could be a flexible or viscous transparent Layer with or mixed therein nano-particles exhibit.

The elongated nano-particles could, for example be realized in the form of metallic ellipsoids, which is a Have a size smaller than λ / 2n is. λ is the wavelength of the used Light and n is the refractive index of the medium or of the material, in which the metallic ellipsoids are embedded. in this respect would the metallic ellipsoids and the embedding medium represent the above material. The metallic ellipsoids have an electric dipole. Free electrons of the dipole can in the electric field, which is induced by the incident light, not in a direction perpendicular to the main axis of the dipole swing. In a direction of movement parallel to the main axis of the In contrast, dipoles can be the electrons of a metallic one Ellipsoids swing; thus establishing a plasmon resonance becomes. In that regard, essentially parallel aligned metallic Ellipsoid anisotropy dar. With appropriate concentration of Metallic nano-particles in the surrounding medium can undergo birefringence realized the metallic ellipsoids and their embedding medium which depends on the orientation of the metallic ellipsoids. A comparable mode of action is metallic Carbo Nano Tubes whose geometry over process parameters in the Manufacturing are adjustable. The length of the metallic Carbo Nano Tubes is also chosen smaller than λ / 2n. In a similar way, metal molecules could of equal magnitude with two in theirs Length significantly different major axes are used.

Concretely, liquid crystals could be arranged between the first and the second substrate and / or between a substrate and an intermediate electrode layer adjacent thereto and / or between two adjacent intermediate electrode layers, which crystals can be influenced in their orientation by applying a specifiable electrical voltage to the electrodes , The electrodes of the first and / or the second substrate preferably each have insulating layers, so that the liquid crystals are not in electrical contact with the electrodes. The insulating layer is also to be selected such that the refractive index is largely matched to that of the electrodes and / or to that of the substrate, and that the insulation layer for the light used is transparent. In this case, it would be possible to compensate for any height differences which may be caused by the application of the electrode material on the substantially planar substrate with the insulating layer. Finally, the insulating layer could also form a substantially planar surface to the layer of liquid crystals.

For a diffraction device based on liquid crystals For example, this can be similar in structure to a ECB-SLM (ECB = Electrically Controlled Birefringence). Usually lies in the absence of an electric field an orientation the liquid crystals largely parallel to the substrate Surface forces. Parallel in this plane to the substrate during manufacture (for example, by mechanical Rubbing) one direction. For this purpose, a layer could be provided be with which the liquid crystals are preoriented can, for example, by the mechanical introduction (eg by brushing) corresponding wells.

Prefers takes place in the case of a diffraction device with linear Electrodes the alignment of the LC molecules on the surface a substrate parallel to the longitudinal direction of the electrodes, because then sharper transitions in the LC Orientation between adjacent electrodes when creating a Tension are possible.

For an arrangement based on activation of liquid crystals based, wherein the dimension of the electrodes in the same order of magnitude is how the thickness of the LC layer is for a phase modulation required by 2π, the case may occur the activation of the LC via the individual electrodes is not completely independent of each other. For example For example, the phase value realized at a certain position in the diffraction device will, not only from the voltage on an electrode, but also depend on the voltage on at least one neighboring electrode.

In contrast to a phase SLM in which an activation for realizing a phase value for this pixel is generally independent for each pixel, it is therefore proposed in one embodiment of the invention to realize blaze gratings of different periods, the voltage values of one set each of electrodes corresponding to a grating period, once to determine that they give the desired phase profile. These voltage values can be z. B. in stored form for the control ready. For this purpose, in particular an arrangement of the electrodes on the opposite substrates may be helpful, as they are in 7 is shown.

With the diffraction device, in particular, diffraction structures are generated with which local phase changes of the light interacting with the diffraction structures of the diffraction device can be realized (phase grating). It could be problematic to realize small periods of the diffraction structures, since possibly only a few electrodes are arranged in a small space, for example only 5, in order to set a predefinable phase adjustment of the diffraction device for a specific operating state. A preferred example of a diffraction structure or a predefinable phase adjustment is a sawtooth profile, which can be realized, for example, with the LC layer of the diffraction device. This is in 8th shown. The electrode arrangement of in 8th shown electrodes is similar to that according to 5 formed, ie above is a sheet-like electrode 32 and opposite are line-shaped electrodes 26 arranged in a plane E ₁ (the substrates are in 8th Not shown). With φ (x) is shown an example of a set phase characteristic of the LC layer which results in light passing through the diffraction device when the electrodes 26 with a distribution of voltages with respect to the potential U _{c of} the electrode 32 be charged.

If the electrodes are made very wide, ie, for example, the duty cycle is increased from 0.5 to 0.8, so that the electrodes occupy 80% of the period, then a less stepped phase ramp could be realized, but the range of the 2π- (phases ) Jump or 2π-stage, which by the reference PS in 8th would be significantly less steep than this 8th the case is. This form of general, locally undifferentiated and non-variably selectable smoothing represents a low-pass filter, ie reduces the highest spatial frequency still to be represented of the synthetic, variable phase grating.

A buried, in the plane E ₂ arranged second layer of transparent electrodes 54 , which for example has the same distance of the first electrode layer and the same or a different duty cycle, can be used to purposefully achieve a smoothing of the step profile at the locations at which a phase ramp is to be realized, and at the same time a sharp edge of the 2π- Level to allow. In 9 this is shown.

In the region of the edge of the sawtooth-shaped phase step, which rises as linearly as possible, the electrodes become 54 the plane E _2, for example, set to the mean value of the voltage of its two adjacent electrodes of the plane E ₁ . Of this rule, however, are the electrodes 54 the Ebe except E ₂ , which lie directly below the 2π jump to be realized. They carry a voltage U _2π , which realizes the sharpest possible edge.

Of the Advantage of a second electrode comb structure buried lies in the fact that on the border of the dissolution of the example used contact copy lithography line widths are used can, for example, be twice as wide as the Line widths that would have to be used if both Electrode comb structures would lie in a common plane.

The level at the top - in 10 not shown substrate - is executed in an advantageous embodiment in the form of two, superimposed electrode comb structures in two different planes E ₃ and E ₄ . This is in 10 shown. In comparison to the design 9 As a result, a steeper course of the edges of the phase stages is achieved. The electrodes 26 . 54 For example, they are made of ITO (Indium Tin Oxide) and embedded in high refractive glass such as SF66 so as not to be optically effective as a phase grating.

With In other words, it is preferably provided that at least one Substrate of the diffraction device electrodes in at least two different and planes parallel to a surface of the substrate are arranged. The arranged in the different levels Electrodes can be arranged laterally offset from each other be. The dimensions of the electrodes and / or their distances with each other can differ or largely be equal.

According to one Particularly preferred embodiment, the electrodes the diffraction device connected such that an electric Field distribution in the diffraction device adjusts, with which at least partially a sawtooth Refractive index distribution with a predeterminable periodicity results. This can be achieved, for example, in that with respect to a Direction of the juxtaposed electrodes, each with different electrical voltages are applied.

Accordingly results between the two substrates of the diffraction device an electric field, with which the between the two substrates arranged material can be influenced such that a set sawtooth refractive index profile. This is an active state in which two and / or three-dimensional image content are generated.

Farther could be provided that in preparation for another active state in which the diffraction device is another Diffraction structure, the electrodes of the diffraction device be connected so that an electric field distribution in the diffraction device, with which a substantially homogeneous refractive index distribution results. Could do this respectively adjacent electrodes of a substrate, each with electrical Voltages of different signs are applied, so that the electric field lines of an example positively charged Electrode to the two adjacent negatively charged electrodes - and not to the oppositely disposed electrode of the other substrate - run. Accordingly, results an electric field distribution whose electric field lines a relatively small angle relative to the surface of the substrate have, so that in a middle area between the two substrates resulting electric field lines, which essentially aligned parallel to the surfaces of the two substrates are. This is an inactive state in which no two- and / or three-dimensional image contents are displayed. This can advantageously arranged between the two substrates Material very quickly converted into a defined neutral state from which the material is returned to an active state can be, in which realizes another diffraction structure becomes.

In order to to realize a high refresh rate for the next one active state a predetermined diffraction structure or refractive index distribution can be set very quickly, according to a preferred embodiment already in the setting a substantially homogeneous refractive index distribution the electrodes the diffraction device connected such that an electric Field distribution yields the ones to be generated next Refractive index distribution prepared. This could be, for example be achieved in that at places where a large refractive index difference or a phase jump should take place, the electrodes arranged there each be subjected to a corresponding voltage, so that in these places - already in the inactive state - a appropriate refractive index distribution is prepared or already partially stops.

In order that a diffraction structure can be adjusted quickly, the electrodes of the diffraction device are each subjected to an initially increased electrical voltage over time, as is necessary for setting the refractive index distribution to be generated. The electrical voltage is then set to values that are used to set the Refractive index distribution is required.

Preferably is in the propagation direction of the light wave field of the diffraction device downstream of a further diffraction device. In the further diffraction device is a diffraction structure of a periodicity adjustable, which has a predeterminable direction or structure that differs from the predeterminable direction or structure of the periodicity a set diffraction structure of the light modulator downstream differs (first) diffraction device. This allows an observer tracking take place in a different direction than that possible with the first diffraction device is.

The two diffraction devices could be arranged in such a way to each other be that the predeterminable direction or the structure of the periodicity the diffraction structure of the (first) diffraction device substantially perpendicular to the predeterminable direction or structure of the periodicity the diffraction structure of the further diffraction device is. In the concrete The first and the second diffraction device could respectively a substrate of substantially linear design, substantially arranged parallel to each other and in a predeterminable direction having aligned electrodes. The two diffraction devices are arranged to each other such that the linear formed Electrodes of the first diffraction device substantially perpendicular to the linearly formed electrodes of the second diffraction device are aligned. The electrodes of the two diffraction devices can in this case arranged in substantially parallel to each other Layers lie.

According to a preferred embodiment, the electrodes of the diffraction device, which are substantially linear and arranged substantially parallel to one another, are oriented at an angle relative to the horizontal in such a way that a light distribution of the light diffracted at the diffraction device results in a viewer plane, which results in an occurrence of light intensities in observer eyes which are adjacent to observer eyes with a visibility area are largely suppressed. This is of particular importance when the light mutation device according to the invention is used for a display for displaying holographic three-dimensional image contents, which according to the in the WO 2006/0669191 A1 described principles works. In this case, a 3D scene coded into the light mutation device can be holographically reconstructed with at least partially coherent light for at least one observer. The observer sees the reconstruction or the three-dimensional scene when his eyes coincide with the visibility region in the observer plane generated for his position. If the observer changes his distance from the display or moves laterally in front of the display, he is tracked to the visibility area. For this purpose, a position detection system determines the position of the observer's eyes, and thus also the deflection angle of the light bundles from the optical axis of the display to the observer eye, and updates the position data. The position detection system is connected to the light modulator via control means. The visibility range of a detected observer eye is specified for a region between two adjacent diffraction orders and thus two adjacent light source images. This prevents that an intensity maximum lies in this eye and disturbs the viewing of the reconstruction. In contrast, the shape of the aperture of the modulator cell determines the distribution of the total intensity of a light source to its generated individual light source images. In principle, crosstalk of the intensities or perception of diffraction orders may occur in an eye adjacent to the currently generated visibility region. This can be reduced or completely suppressed with different approaches. A similar effect could be caused by the at least one diffraction device arranged downstream of the light modulator, which diffraction device is likewise to be reduced or suppressed. This can be achieved by the corresponding orientation of the electrodes at a predeterminable angle relative to the horizontal.

Of the Light modulator and / or the diffraction device points along at least one direction a periodic structure with a predeterminable periodicity on. The light modulator usually has a matrix-shaped Structure on, d. H. a lattice structure in two different Directions. The diffraction device preferably has a periodic structure in only one direction. In concrete terms, it is envisaged that the light modulator and the diffraction device a periodic Having structure with a predetermined periodicity. The periodicity of the diffraction device is less than the periodicity of the light modulator or the periodicity the diffraction device is equal to the periodicity of Light modulator. The periodicity of the diffraction device could, for example, be smaller by a factor than the periodicity of the light modulator having a value which is in one Range is between 2 and 150.

The diffraction device has individual diffraction elements into which binary, discrete or continuous values can be set. These values could correspond in particular to adjusted orientations of the liquid crystals which cause corresponding phase changes of the light passing through the respective diffraction element of the diffraction device. The set or Inscribed values of the diffraction elements of the diffraction device form the diffraction structure. In particular, a diffraction element could be an electrode and the LC material arranged at this electrode.

A Field lens function for the display could thereby be achievable that predetermined phase terms in the diffraction device be enrolled.

alternative or additionally could be a focusing optical Component be provided with which a field lens function for the display can be realized. The focusing optical component could be in the form of a Bragg grid predeterminable property be executed.

As already indicated, could be a temperature compensation be provided, which an active temperature control with at least a temperature sensor and at least one thermodynamic element - for example a Peltier element - has. A Peltier element can doing locally for cooling, heating and / or for temperature measurement (U (T)) are used. Alternatively or in addition could be a temperature compensation by registered mail realized a predetermined phase profile in the light modulator become.

One predefinable deflection angle for light of different wavelengths would be adjustable even if the light modulator and the diffraction device is time-sequential with light of different wavelengths be illuminated. Synchronous to this one will be used on the currently used Wavelength of light tuned diffraction structure in the diffraction device inscribed. This can be for the three Basic colors red, green and blue take place, giving a color representation the image content is possible with the display.

Prefers the diffraction device is arranged adjacent to the light modulator. An optionally provided further diffraction device is arranged adjacent to the first diffraction device. Adjacent In this context, it should be understood in particular that none another optical component between the light modulator and the diffraction device or between the two diffraction devices is arranged or that the respective components are in close proximity are arranged to each other. With in close proximity could be a distance range of 0 to 10 mm. It is also conceivable that at least two of the following components designed as a sandwich: the light modulator, the diffraction device and the other diffraction device. In this case, the manufacturing process one component directly attached to the other component Service. Individual components of the sandwich could be one Have common component, in particular a substrate. In the Sandwich could also implement the field lens function Be integrated component.

In terms of a display is the task given by the teaching of claim 32 solved. Accordingly an inventive display characterized by a light modulation device according to any one of the claims 1 to 31. The display is designed such that stereoscopic image content and / or stereoscopic multi-view image content and / or holographic Image content can be displayed. Such a display (3D display) is So able to create three-dimensional image content for the human Representing perception in three dimensions. Regarding the possible Embodiments of the light modulation device is avoided from repetitions to the previous part of the description directed.

For 3D displays, it is advantageous to switch between a 3D mode and a 2D mode to realize where transmit conventional two-dimensional image data in 2D mode or can be displayed.

in principle it is for the inventive 3D display conceivable to maintain the viewer tracking, and re of the displayed content, the information for the 3D scene by replacing a 2D image content. Would be advantageous However, to realize a switch to a 2D display in the way that a stationary large viewer area is present and no tracking of a small observer window is required to the current eye position of the viewer.

• (a) Es ist eine zusätzliche optische Einrichtung vorgesehen, welche in dem Aufbau und in der Form ein schaltbares streuendes Medium umfasst. Im inaktiven bzw. ausgeschalteten Zustand ist das Medium transparent. Im eingeschalteten Zustand wirkt das Medium streuend. Als schaltbares Streumedium kommen beispielsweise Polymer Dispersed Liquid Crystals (PDLC) in Frage. Die zusätzliche optische Einrichtung könnte auf der dem Betrachter zugewandten Seite des Displays angeordnet sein, sozusagen als letzte optische Komponente des Displays. Im aktiven Zustand der optischen Einrichtung wäre die Beugungseinrichtung zu deaktivieren. Hierdurch wäre der 2D-Modus des 3D-Displays realisiert. Falls die optische Einrichtung deaktiviert und die Beugungseinrichtung aktiviert ist, befindet sich das 3D-Display im 3D-Modus. Bei dieser Möglichkeit ist daher eine zusätzliche Komponente im Aufbau erforderlich.

Therefore, two possibilities of 3D-2D switching are proposed:

• (A) An additional optical device is provided, which comprises in the structure and in the form of a switchable scattering medium. When inactive or switched off, the medium is transparent. When switched on, the medium has a scattering effect. Suitable switchable scattering medium are, for example, polymer-dispersed liquid crystals (PDLC). The additional optical device could be arranged on the side of the display facing the observer, so to speak as the last optical component of the display. In the active state of the optical device, the diffraction device would be deactivated. This would realize the 2D mode of the 3D display. If the optical device is deactivated and the diffraction device is activated, the 3D display is in 3D mode. With this possibility, therefore, an additional component is under construction required.

• (b) Die Beugungseinrichtung selbst wird zwischen zwei Betriebsmodi umgeschaltet. In dem einen Betriebsmodus (3D-Modus) wird die Beugungseinrichtung derart angesteuert, dass sie auf eine gezielte Position Licht ablenkt. In dem anderen Betriebsmodus (2D-Modus) wird die Beugungseinrichtung derart angesteuert, dass sie eine streuende Funktion aufweist. Dazu wird eine codierte Diffusorfunktion verwendet. Dies kann beispielsweise durch eine zufällige Phasenverteilung oder auch durch eine gezielt optimierte Phasenverteilung realisiert werden, die anstelle eines regelmäßigen Gitters durch entsprechende Ansteuerung in der Beugungseinrichtung eingestellt wird. Werden zwei gekreuzte Beugungseinrichtungen verwendet, so wird die erste zur horizontalen und die zweite zur vertikalen Streuung verwendet.

The second preferred option is:

• (b) The diffraction device itself is switched between two modes of operation. In the one operating mode (3D mode), the diffraction device is driven in such a way that it deflects light to a specific position. In the other operating mode (2D mode), the diffraction device is driven in such a way that it has a scattering function. For this a coded diffuser function is used. This can be realized for example by a random phase distribution or by a specifically optimized phase distribution, which is adjusted instead of a regular grid by appropriate control in the diffraction device. If two crossed diffraction devices are used, the first is used for horizontal and the second for vertical dispersion.

Holographic displays use full-parallax holograms or single-parallax holograms. Single-parallax holograms represent a simplification with regard to the computation or coding effort. Single-parallax holograms permit, inter alia, the use of a lighting device which is coherent only in the coding direction or in the parallax direction. In one direction (the coding direction) a viewer window can be generated, in another direction (perpendicular thereto) a sweet spot, compare for example WO 2006/027228 A1 ,

A Diffraction device required for viewer tracking usually coherent light. It is not that requires coherence over the entire area the diffraction device is present. It is for the function Rather, the diffraction device is sufficient if the coherence over some Periods of the grid is present.

It is therefore proposed, a lighting device (under use the well-known van-Cittert-Zernike theorem) in their dimensions, Properties and in particular in their angle spectrum regarding the distribution of the pointing vectors emitted by the illumination device Make light so that the viewer tracking in a single-parallax hologram coding perpendicular to the coding direction with there is partial coherence of a diffraction device, such that multiple grating periods of the diffraction device still largely spatially coherently illuminated to each other but different pixels of the SLM are largely incoherent to each other. This allows the viewer tracking be carried out coherently, but continue to do so Sweet spot to be generated.

at a pixel pitch of the SLM of, for example, 50 microns and a Pitch of the diffraction device of 2 microns, it would be for example, possible, about 25 grating periods of the diffraction device coherently, but adjacent pixels of the SLM largely incoherent to illuminate.

• a) Beschichten eines ersten Substrats mit Elektroden,
• b) Aufbringen einer Materialschicht auf einer Oberfläche des ersten Substrats,
• c) Aufbringen eines zweiten, mit Elektroden beschichteten Substrats, wobei die zwei Substrate derart zueinander ausgerichtet werden, dass die linear ausgebildeten und parallel zueinander angeordneten Elektroden des ersten Substrats im Wesentlichen parallel zu den linear ausgebildeten und parallel zueinander angeordneten Elektroden des zweiten Substrats ausgerichtet sind.

With regard to the method for producing a light modulation device, the object mentioned in the introduction is achieved by the teaching of claim 35. Accordingly, the inventive method for producing a light modulation device according to one of claims 1 to 31 is used. The manufacturing method comprises the following method steps:

• a) coating a first substrate with electrodes,
• b) applying a layer of material on a surface of the first substrate,
• c) applying a second electrode-coated substrate, wherein the two substrates are aligned such that the linearly formed and mutually parallel electrodes of the first substrate are aligned substantially parallel to the linearly formed and arranged parallel to each other electrodes of the second substrate.

in the Step b) could be, for example, a thin polymer film be laminated, the liquid crystals or carbon nano Tubes or metallic elliptical nanoparticles contains.

According to step e) could now another layer of material, for example another polymer film to be laminated.

• d) nach Schritt b) wird eine Elektroden aufweisende Zwischenelektrodenschicht auf die Materialschicht aufgebracht,
• e) auf der Zwischenelektrodenschicht wird eine weitere Materialschicht aufgebracht.

Furthermore, the further method steps could be provided:

• d) after step b) an electrode electrode having intermediate electrode layer is applied to the material layer,
• e) on the intermediate electrode layer, a further material layer is applied.

The Steps d) and e) can be performed at least once more become.

in this connection could be the first substrate and the at least one inter-electrode layer be aligned with each other so that the linear formed and electrodes of the first substrate arranged parallel to one another essentially parallel to the linear and parallel arranged electrodes of the intermediate electrode layer are aligned.

For applying electrodes to a substrate according to method step a) or to a material layer according to method step d), a "lift Off "process to be used. Alternatively, electrodes could be deposited by depositing an electrically conductive film of liquid or gas phase onto the substrate or onto the material layer. A photoresist is laminated, spin-coated or even sprayed on. The photoresist is exposed with a striped pattern. The exposure can z. B. done in contact copy. The strips can also be produced in the form of a two-beam interference pattern. The exposed photoresist is z. B. developed with KOH (AZ Hoechst). The exposed lines of the conductive layer are etched away with a solution. The remainder, ie remaining photoresist is removed with Remover. The gaps between the electrodes could be filled by z. B. a non-conductive, sufficiently transparent material from the liquid or gas phase is deposited.

It Now there are different ways of teaching the present Invention in an advantageous manner and further develop. On the one hand is subordinate to the claim 1 Claims and on the other hand to the following explanation of the preferred embodiments of the invention to refer to the drawing. In conjunction with the explanation of the preferred embodiments of the invention The drawings are also generally preferred embodiments and further developments of the teaching explained. In the drawing each show in a schematic representation

1 in a plan view a first embodiment of the present invention,

2 in a plan view, a second embodiment of the present invention,

3 an example of a diffraction structure inscribed in the diffraction device in a schematic diagram representation,

4 in a partial exploded view of a first embodiment of a structure of a diffraction device,

5 in a sectional view of a part of the diffraction device 4 .

6 in a sectional view a part of another embodiment of a diffraction device,

7 in a sectional view a part of another embodiment of a diffraction device,

8th to 11 each in a side view part of another embodiment of a diffraction device and the hereby adjustable phase delay,

12 in a schematic representation, the orientation of the electrodes of a first and a second diffraction device,

13 to 15 each in a side view of a part of a diffraction device, which is respectively controlled differently or which is in different operating conditions and

16 in a schematic diagram, a voltage curve as a function of time, with which an electrode of the diffraction device can be acted upon.

In The figures are the same or similar components with the same Reference number marked.

1 shows a light modulation device 10 for a not shown in the figures display for displaying two- and / or three-dimensional image content. The light modulation device 10 has a light modulator ( 12 , SLM) and a control device 14 on. The light modulator 12 is using a collimated lightwave field 16 illuminated by the in 1 indicated arrows is indicated. The phase and / or amplitude of the collimated lightwave field 16 can with the light modulator 12 depending on the location of the light modulator 12 to be changed. For this purpose, the light modulator 12 individual (enlarged) pixels 18 on, which are arranged in a matrix. The light modulator 12 is from the controller 14 driven. According to the invention in the propagation direction of the lightwave field 16 the light modulator 12 at least one controllable diffraction device 20 downstream. The diffraction device 20 is also from the controller 14 controlled, but could be controlled by a separate control unit. Depending on the control of the diffraction device 20 has the diffraction device 20 a variable diffraction structure. With the diffraction structure that is the light modulator 12 changed light wave field 16 variably bent in a predeterminable manner.

In 3 is a schematic diagram of an example of one in the diffraction device 20 inscribed diffraction structure 22 shown. Here is the light wave field 16 through the diffraction device 20 markable phase delay as a function of the pixels or of the location in the horizontal direction / X direction of the light modulator 12 shown. The diffraction device 20 is formed such that with the diffraction device 20 adjustable diffraction structure 22 is variable in the periodicity. In concrete terms, the periodicity 24 the diffraction structure 22 be enlarged or reduced. Also the shape of the diffraction structure 22 is changeable. So z. B. a rectangular function, a sawtooth function, a sine function or another predetermined function by discrete steps or continuously (depending on the specific structural design of the diffraction device 20 ) or exactly in the diffraction device 20 be enrolled.

4 shows an embodiment of a diffraction device in a partial exploded view 20 with substantially linearly formed and substantially mutually parallel electrodes 26 , The electrodes 26 are on a first substrate 28 arranged and extend substantially over the entire length of the substrate 28 , At the top of the electrodes 26 or the first substrate 28 are contacts 29 for the electrodes 26 provided with which the electrodes 26 can be contacted electrically and from an in 4 Not shown control device can be acted upon by electrical voltage. The diffraction device 20 has a second substrate 30 on which of the first substrate 28 spaced apart. The second substrate 30 has a sheet-like electrode 32 on.

5 shows the diffraction device 20 in a sectional view, wherein the diffraction device 20 is to continue to think to the left and to the right or on both sides so that the diffraction device 20 spread over the entire width of the 1 shown light modulator 12 extends. The width B of the strip-shaped and on the first substrate 28 provided electrodes 26 is 1.5 microns in this embodiment. The width of the gap G between two adjacent electrodes 26 is 0.5 μm. Other values for the stripe width of the electrodes 26 and the spaces between adjacent electrodes 26 are possible and depend in particular on the application of the display and the specific design of the light modulator 12 from. 6 shows in a sectional view another embodiment of a diffraction device 20 , here both on the first substrate 28 as well as on the second substrate 30 in each case strip-shaped electrodes 26 are provided.

7 shows in a sectional view another embodiment of a diffraction device 20 which is essentially similar in structure to that in 6 shown diffraction device 20 is trained. At the in 7 shown diffraction device 20 are the ones on the upper substrate 28 arranged electrodes 26 opposite to the lower substrate 28 arranged electrodes 26 laterally offset from each other.

Between the first substrate 28 and the second substrate 30 the in 5 and 6 shown diffraction device 20 is a layer 34 provided with liquid crystals (Liquid Crystals = LC). The liquid crystals can be influenced in their orientation by the fact that at the electrodes 26 a predetermined electrical voltage is applied. With the reference number 36 is an insulating layer characterized, which prevents the liquid crystals with the electrodes 26 respectively. 32 to be in electrical contact.

The electrodes 26 respectively. 32 of the first and second substrates 28 . 30 are transparent to the light used. The same applies to the first and the second substrate 28 . 30 , The refractive index of the electrodes 26 . 32 essentially corresponds to the refractive index of the substrate 28 respectively. 30 , The refractive index of the electrodes 26 . 32 In addition, it also essentially corresponds to the refractive index of the insulating layer 36 ,

2 shows a further embodiment of a light modulation device according to the invention 10 in which in the propagation direction of the lightwave field 16 the first diffraction device 20 another diffraction device 38 is subordinate. In the further diffraction device 38 For example, a diffraction structure of a periodicity that has a direction Y or structure that is different from the direction X or structure of the periodicity can be set 24 a set diffraction structure 22 the light modulator 12 downstream (first) diffraction device 20 different. In concrete terms are the two diffraction devices 20 . 38 arranged such that the direction X or the structure of the periodicity 24 the diffraction structure 22 the first diffraction device 20 substantially perpendicular to the direction Y or structure of the periodicity of the diffraction structure of the further diffraction device 38 stands. Accordingly, with the first diffraction device 20 a tracking of Bertachteraugen a viewer in the horizontal direction X done. With the second diffraction device 38 can be a tracking of the viewer's eyes of a viewer in the vertical direction Y.

The first and the second diffraction device 20 . 38 each have a substrate having substantially linearly formed and substantially mutually parallel electrodes 26 on. The two diffraction devices 20 . 38 are arranged to each other such that the linearly formed electrodes 26 the first diffraction device 20 substantially perpendicular to the linearly formed electrodes 26 the second diffraction device 38 are aligned. The light modulator 12 and the first and the second diffraction device 20 . 38 be from the controller 14 driven.

The light modulator 12 and the diffraction device 20 have a periodic structure with a predeterminable periodicity, wherein the periodicity of the diffraction device 20 smaller than the periodicity of the light modulator 12 is. Specifically, the periodicity of the diffraction device is 20 depending on the control and the specific embodiment 2 microns. The periodicity of the light modulator is 50 μm in the horizontal and in the vertical direction. To avoid moiré effects, a non-periodic period can also be used.

The electrodes 26 the diffraction device 38 can be considered as individual diffractive elements into which - in cooperation with a part of the liquid crystal layer 34 - Discrete or continuous values can be set by applying predeterminable electrical voltages.

In the in the 1 and 2 shown displays is a field lens function of the display can be achieved that a trained in the form of a Bragg grating focusing optical component 40 is provided. With the component become the light rays of the light wave field 16 that the light modulator 12 go through, in the direction of the central viewer positions 42 focused or distracted. The central viewer positions 42 are symmetrical to the middle axis 44 the light modulation device 10 and at a distance D from the light modulator 12 arranged. The central viewer positions 42 consist of two viewer windows 46 . 48 , With the diffraction device 20 it is possible a lateral tracking of the viewer window 46 . 48 to the current position of the observer's eyes 50 . 52 thereby ensuring that appropriate diffraction structures 22 in the diffraction device 20 be enrolled. The tracked observer windows are denoted by the reference numerals 46 ' and 48 ' characterized.

The display, which one in the 1 or 2 shown light modulation device 10 and / or which is designed according to one of claims 1 to 20, may in concrete be configured such that stereoscopic and / or stereoscopic multi-view image contents and / or holographic image contents can be displayed.

11 shows a schematic side view of another embodiment of a diffraction device 20 which is essentially similar in structure to that in 6 shown diffraction device 20 is trained. At the in 11 shown diffraction device 20 are three intermediate electrode layers 56 intended. Each intermediate electrode layer 56 has several electrodes 58 on, whose width, spacing and arrangement substantially the width, spacing and arrangement of the electrodes 26 which correspond to the first substrate 28 or on the second substrate 30 are arranged. Between the first substrate 28 and the intermediate electrode layer adjacent thereto 58 is a material 62 arranged, which has a polyimide layer. The polyimide layer is such that, on the one hand, it has an essentially form-invariant structure and, on the other hand, has spaces (not shown) in which liquid crystals are arranged. By applying electrical voltages to the individual electrodes 26 respectively. 58 For example, the liquid crystals freely floating in the polyimide layer can be aligned according to the field distribution of the resulting electric field, and accordingly, the diffraction means 20 affect passing light. Between the intermediate electrode layers 56 and between the second substrate 30 and the intermediate electrode layer adjacent thereto 56 is also the material 62 arranged. Each with solid lines are insulating layers 64 indicated, which in the manufacturing process of the diffraction device according to the invention 20 prevent the electrode material of the electrodes applied in a coating process 58 in the material layer 62 diffused.

The electrodes 58 the intermediate electrode layers 56 could be in the respective intermediate electrode layer 56 laterally offset to the electrodes 26 of the first and second substrates, respectively 28 . 30 be arranged. It is also conceivable, the width and the respective distance of the electrodes 58 at least one intermediate electrode layer 56 deviating from the width or the distance of the electrodes 26 to choose.

12 shows a schematic representation of an embodiment of an alignment of the electrodes 26 a first diffraction device 20 opposite the electrodes 26 a second diffraction device 20 ' , Here are the electrodes 26 the first diffraction device 20 at an angle α = 55 degrees to the horizontal 60 arranged. The electrodes 26 the second diffraction device 20 ' are at an angle α + 90 degrees = 145 degrees from the horizontal 60 arranged. Accordingly, the electrodes 26 the first diffraction device 20 perpendicular to the electrodes 26 the second diffraction device 20 ' aligned. In such an arrangement of the electrodes 26 on the respective substrates of the diffraction devices 20 . 20 ' can the electrodes 26 be contacted on all four sides of the respective substrate.

The 13 to 15 show one each Part of a diffraction device 20 , In the 13 shown diffraction device 20 is in an inactive for the representation of image content, in which the electric field lines 66 is aligned in a central region between the two substrates substantially parallel to the surface of the substrates. This is done in this embodiment in that in each case adjacent electrodes of a substrate with respective electrical voltages of different sign (with + or - indicated) are applied, so that the electric field lines 66 from a positively charged electrode 26 to the two adjacent negatively charged electrodes 26 - And not to the opposite electrode arranged 26 of the other substrate - run. In this way, advantageously, the material (not shown) arranged between the two substrates can very quickly be converted into a defined neutral state, from which the material is returned to an active state, in which another diffraction structure is realized.

Alternatively to the in 13 The wiring of the electrodes shown could also be an in 14 shown circuitry may be provided to the electrodes, according to which the electrodes of the two substrates are subjected to a substantially wedge-shaped voltage waveform. Both the electrodes of the first and the electrodes of the second substrate are in this case subjected to electrical voltage of the same polarity. This could be realized by applying a predeterminable voltage (indicated by "1+") to the electrode marked on the far left and to the electrodes adjacent thereto on the right in each case a slightly higher predetermined additional voltage (indicated by "2+", .. ., "16+"). In that regard, this results in an electric field distribution, which in the right area of the diffraction device 20 is formed most strongly between the two substrates and which drops substantially wedge-shaped to the left. This is due to the thickness of the electric field lines 66 in 14 indicated. It should be noted that in the 13 to 15 drawn field lines 66 are indicated only schematically. In the given or other wiring of the electrodes different configurations may result for the actual electric field lines.

In 15 is another embodiment of a wiring of the electrodes 26 the diffraction device 20 shown in an inactive for the image display state. In this case, even when setting a substantially homogeneous refractive index distribution, the electrodes 26 the diffraction device 20 such that an electric field distribution results which prepares the refractive index distribution φ (x) (shown dotted) to be generated next. This is achieved by placing in places 68 at which a large refractive index difference or a phase jump is to take place, the electrodes arranged there 26 are each acted upon by a predetermined positive voltage, so that at these points - even in the inactive state - a corresponding refractive index distribution is prepared. The remaining electrodes 26 are applied with a predetermined negative voltage. As a result, a predefinable diffraction structure or refractive index distribution can be set very quickly for the next active state, which allows a high refresh rate.

16 shows an embodiment of a voltage curve as a function of time, with which an electrode 26 the diffraction device 20 can be applied. Accordingly, at least one electrode 26 the diffraction device 20 in the course of time, in each case with an initially increased electrical voltage U ₀ applied, as this is initially required for setting the refractive index distribution to be generated. The electrical voltage is then set in each case to a value U _S , which is required for setting the refractive index distribution to be generated. As a result, another diffraction structure can also be adjusted very quickly in an advantageous manner.

Finally be particularly noted that the above discussed Embodiments only for the description of the claimed Doctrine serve, but not on the embodiments limit.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• WO 2005/060270 A1 [0003]
• WO 2006/066919 A1 [0003, 0011]
• WO 2006/027228 A1 [0003, 0094]
• - WO 2006/119920 A1 [0004]
• WO 2008/142108 A1 [0004]
• - WO 2006/066906 A1 [0006]
• - DE 102008002692 [0030]
• - EP 2009/050476 [0030]
• - DE 102009027093 [0038]
• WO 2006/0669191 A1 [0081]

Claims (37)

Light modulation device for a display for displaying two- and / or three-dimensional image contents, with a light modulator ( 12 , SLM) and a control device ( 14 ), wherein the phase and / or the amplitude of a substantially collimated light wave field ( 16 ) with the light modulator ( 12 ) depending on the location on the light modulator ( 12 ) is variable, wherein the light modulator ( 12 ) with the control device ( 14 ) is controllable, characterized in that in the propagation direction of the light wave field ( 16 ) the light modulator ( 12 ) at least one controllable diffraction device ( 20 . 38 ), which depends on the activation of the diffraction device ( 20 ) a variable diffraction structure ( 22 ), and that with the diffraction structure ( 22 ) from the light modulator ( 12 ) Modified light wave field changeable deflectable in a predeterminable manner. Light modulation device according to claim 1, characterized in that the diffraction device ( 20 ) is designed such that with it a predetermined grid-shaped or sawtooth-shaped diffraction structure ( 22 ) is adjustable, which extends only in a predetermined direction (X). Light modulation device according to claim 1 or 2, characterized in that the diffraction device ( 20 ) is designed such that with the diffraction device ( 20 ) adjustable diffraction structure ( 22 ) in the periodicity ( 24 ) is changeable. Light modulation device according to one of claims 1 to 3, characterized in that the diffraction device ( 20 ) substantially linearly formed and arranged substantially parallel to each other electrodes ( 26 ), which on a first substrate ( 28 ) are arranged. Light modulation device according to claim 4, characterized in that the diffraction device ( 20 ) a second substrate ( 30 ), which of the first substrate ( 28 ) and that the second substrate ( 30 ) a sheet-like electrode ( 32 ) or a plurality of substantially linearly formed and substantially mutually parallel electrodes ( 26 ) having. Light modulation device according to one of claims 4 to 5, characterized in that the electrodes ( 26 . 32 ) of the first and / or second substrate ( 28 . 30 ) are transparent to the light used and / or that the first and / or the second substrate ( 28 . 30 ) is transparent to the light used. Light modulation device according to one of claims 4 to 6, characterized in that on at least one substrate electrodes ( 26 . 32 ) are arranged in at least two different planes parallel to a surface of the substrate, and in that the electrodes arranged in the different planes ( 26 . 54 ) are laterally offset from each other. Light modulation device according to one of claims 4 to 7, characterized in that between two substrates ( 28 . 30 ) at least one intermediate electrode layer ( 56 ) - preferably four intermediate electrode layers - is or are and that the intermediate electrode layer ( 56 ) Electrodes ( 58 ) having. Light modulation device according to claim 8, characterized in that the electrodes ( 58 ) of the interelectrode layer ( 56 ) are formed substantially linearly, arranged substantially parallel to one another and aligned in a predeterminable direction. Light modulation device according to claim 8 or 9, characterized in that the distance between a substrate ( 28 ) and an adjacent intermediate electrode layer ( 56 ) and / or between two adjacent intermediate electrode layers ( 56 ) is predetermined and preferably a fraction of the distance between two adjacent electrodes ( 26 ; 56 ) or the grating period of the electrodes ( 26 ; 56 ) of the substrate ( 28 ) or the interelectrode layer ( 56 ), for example 1/2 or less. Light modulation device according to one of claims 4 to 10, characterized in that the linearly formed and mutually parallel electrodes ( 26 . 32 ) of the first and / or second substrate ( 28 . 30 ) and / or an intermediate electrode layer ( 56 ) are aligned in a predeterminable direction. Light modulation device according to one of claims 4 to 11, characterized in that the linearly formed and mutually parallel electrodes ( 26 . 32 ) of the first and / or second substrate ( 28 . 30 ) and / or an intermediate electrode layer ( 56 ) are aligned substantially parallel to each other. Light modulation device according to one of claims 4 to 12, characterized in that the refractive index of the electrodes ( 26 . 32 ) substantially the refractive index of the substrate ( 28 . 30 ) or that the electrode material and the substrate material are designed such that they have substantially the same refractive index. Light modulation device according to one of claims 4 to 13, characterized in that between the first and the second substrate ( 28 . 30 ) and / or between a substrate ( 28 ) and an adjacent intermediate electrode layer ( 56 ) and / or between two adjacent intermediate electrode layers ( 56 ) a material is arranged with which local changes in the refractive index for at least one polarization direction of the light can be achieved by adjusting a material influencing the control variable. Light modulation device according to claim 14, characterized characterized in that the material is liquid crystals or that the material is a polymer layer - in particular a Polyimide layer - with liquid crystals or with elongated nano-particles, for example Carbo Nano Tubes, or that the material is a flexible or viscous layer having elongated nano-particles. Light modulation device according to one of claims 4 to 15, characterized in that between the first and the second substrate ( 28 . 30 ) and / or between a substrate ( 28 ) and an adjacent intermediate electrode layer ( 56 ) and / or between two adjacent intermediate electrode layers ( 56 ) Liquid crystals ( 34 ) are arranged, which in their orientation can be influenced by the fact that at the electrodes ( 26 . 32 ) A predetermined electrical voltage is applied, and that means could be provided, with which a pre-alignment of the liquid crystals in a direction parallel to the linear direction of the electrodes can be predetermined. Light modulation device according to one of claims 4 to 16, characterized in that the electrodes of the diffraction device ( 20 ) are connected such that an electric field distribution in the diffraction device ( 20 ), with which results at least partially a sawtooth refractive index distribution with a predeterminable periodicity. Light modulation device according to one of claims 4 to 17, characterized in that the electrodes of the diffraction device ( 20 ) are connected such that an electric field distribution in the diffraction device ( 20 ), which results in a substantially homogeneous refractive index distribution. Light modulation device according to claim 18, characterized in that for setting a substantially homogeneous refractive index distribution, the electrodes of the diffraction device ( 20 ) such that an electric field distribution results which prepares the refractive index distribution to be generated next. Light modulation device according to one of claims 4 to 19, characterized in that the electrodes of the diffraction device ( 20 ) are each subjected to an initially increased electrical voltage in the course of time, as this is necessary for adjusting the refractive index distribution to be generated, and that the electrical voltage is then set in each case to values which is required for adjusting the refractive index distribution to be generated. Light modulation device according to one of claims 1 to 20, characterized in that in the propagation direction of the light wave field ( 16 ) of the diffraction device ( 20 ) a further diffraction device ( 38 ) is arranged downstream, that in the further diffraction device ( 38 ) a diffraction structure of a periodicity is adjustable, which has a predeterminable direction (Y) or structure which differs from the predeterminable direction (X) or structure of the periodicity ( 24 ) of a set diffraction structure ( 22 ) of the light modulator ( 12 ) downstream diffraction device ( 20 ) is different. Light modulation device according to one of claims 1 to 21, characterized in that the two diffraction devices ( 20 . 38 ) are arranged to one another such that the predeterminable direction (X) or the structure of the periodicity ( 24 ) of the diffraction structure ( 22 ) of the diffraction device ( 20 ) substantially perpendicular to the predeterminable direction (Y) or structure of the periodicity of the diffraction structure of the further diffraction device ( 38 ) stands. Light modulation device according to one of claims 1 to 22, characterized in that the first and the second diffraction device ( 20 . 38 ) one substrate each ( 28 ) having substantially linearly formed, substantially parallel to each other and aligned in a predetermined direction electrodes ( 26 ) and that the two diffraction devices ( 20 . 38 ) are arranged to each other such that the linearly formed electrodes ( 26 ) of the first diffraction device ( 20 ) substantially perpendicular to the linearly formed electrodes ( 26 ) of the second diffraction device ( 38 ) are aligned. Light modulation device according to one of claims 4 to 23, characterized in that the substantially linearly formed and substantially mutually parallel electrodes ( 26 ) at an angle (α) relative to the horizontal ( 60 ) are aligned such that a light distribution of the at the diffraction device ( 20 ) diffracted light in a viewer plane, which indicates an occurrence of light intensities in observer eyes, which are adjacent to observer eyes with a visibility area, are largely suppressed. Light modulation device according to one of claims 1 to 24, characterized in that the light modulator ( 12 ) and / or the diffraction device ( 20 . 38 ) has a periodic structure with a predeterminable periodicity. Light modulation device according to one of claims 1 to 25, characterized in that the light modulator ( 12 ) and the diffraction device ( 20 . 38 ) have a periodic structure with a predeterminable periodicity and that the periodicity of the diffraction device ( 20 . 38 ) smaller than the periodicity of the light modulator ( 12 ), for example by a factor that has a value that is in a range between 2 and 150. Light modulation device according to one of claims 1 to 26, characterized in that the diffraction device ( 20 . 38 ) has individual diffraction elements into which discrete or continuous values can be set. Light modulation device according to one of claims 1 to 27, characterized in that a field lens function of the display can be achieved in that predeterminable phase terms in the diffraction device ( 20 . 38 ) and / or that a focusing optical component ( 40 ) is provided, for example, a Bragg grating specifiable property. Light modulation device according to one of claims 1 to 28, characterized by a temperature compensation, which has an active temperature control with at least one temperature sensor and at least one thermodynamic element - for example a Peltier element - and / or which by writing a predetermined phase curve in the light modulator ( 12 ) is feasible. Light modulation device according to one of claims 1 to 29, characterized in that the light modulator ( 12 ) and the diffraction device ( 20 . 38 ) is time-sequentially illuminatable with light of different wavelength, that in synchronism therewith a diffraction structure tuned to the currently used wavelength of the light ( 22 ) in the diffraction device ( 20 . 38 ), whereby with the tuned diffraction structure ( 22 ) A predeterminable deflection angle for light of different wavelengths is adjustable. Light modulation device according to one of claims 1 to 30, characterized in that the diffraction device ( 20 ) is arranged adjacent to the light modulator and / or that an optionally provided further diffraction device ( 38 ) adjacent to the first diffraction device ( 20 ) is arranged. Display characterized by a light modulation device ( 10 ) according to one of claims 1 to 31, wherein the display is designed such that stereoscopic and / or stereoscopic multi-view image content and / or holographic image content can be displayed. Display according to Claim 32, characterized a controllable optical device is provided, which in an operating state optically substantially transparent and optically scattering in another operating state, and that by controlling the optical device, the display in one 3D mode or in a 2D mode is operable. Display according to claim 32, characterized in that for operating the display in a 3D-mode with the diffraction device ( 20 ) in a first operating mode, a viewer tracking is feasible and that for operating the display in a 2D mode in a second operating mode, the diffraction device ( 20 ) is controllable such that it has a scattering function. Method for producing a light modulation device ( 10 ) according to one of claims 1 to 31, which comprises the following method steps: a) coating of a first substrate ( 28 ) with electrodes ( 26 ), b) application of a material layer ( 62 ) on a surface of the first substrate ( 28 ), c) applying a second, with electrodes ( 26 ) coated substrate ( 30 ), the two substrates ( 28 . 30 ) are aligned with each other in such a way that the linearly formed and mutually parallel electrodes ( 26 ) of the first substrate ( 28 ) substantially parallel to the linearly formed and mutually parallel electrodes ( 26 ) of the second substrate ( 30 ) are aligned. A method according to claim 35, which comprises the further method steps: d) wherein after step b) an electrode ( 58 ) having intermediate electrode layer ( 56 ) on the material layer ( 62 ) is applied, e) wherein on the intermediate electrode layer ( 56 ) another layer of material ( 62 ) and f) wherein steps d) and e) could be carried out at least once more. The method of claim 36, wherein the first Substrate ( 28 ) and the at least one intermediate electrode layer ( 56 ) are aligned with each other in such a way that the linearly formed and mutually parallel electrodes ( 26 ) of the first substrate ( 28 ) substantially parallel to the linearly formed and mutually parallel electrodes ( 58 ) of the interelectrode layer ( 56 ) are aligned.

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