Light modulation device with high light efficiency

Abstract

The invention relates to a light modulation device having pixels. Roughly half of the pixels are reflective pixels and the other half of the pixels are transmissive pixels. The reflective pixels are arranged in an alternating pattern with the transmissive pixels in the same substrate plane. The light modulation device further has a backplane having transistors and data lines for conducting signals to the pixels. Each pixel is assigned at least one transistor and at least two data lines. The transistors and data lines of each adjacent pair of a reflective pixel and a transmissive pixel are arranged underneath the reflective pixel.

Description

[0001] The present invention relates to a light modulating device which can be used in a display device for holographic reconstruction of an object or a scene. In particular, the present invention relates to a spatial light modulating device, in particular using a planar combination of adjacent modulating elements or pixels. In principle, the application of such a light modulating device in a display device can be found in mobile applications such as smartphones and tablets. However, other applications such as displays or televisions can also be present.

[0002] Furthermore, the present invention also relates to a display device, in particular a holographic display device, comprising such a spatial light modulating device according to the present invention. The display device is used to generate a two-dimensional and / or three-dimensional representation of a scene or content or object.

[0003] The present spatial light modulating device and display device are configured to be able to generate and display or represent two-dimensional (2D) and / or three-dimensional (3D) images. Of course, a two-dimensional image or a three-dimensional image also comprises two-dimensional or three-dimensional content or movies.

[0004] Direct view displays, projection displays (e.g. head-mounted displays (HMD)) and head-up displays (HUD) for a preferred three-dimensional representation of holographic images / content can also be considered as application fields of the present invention.

[0005] Today, flat panel displays with a screen thickness of less than or equal to a few centimeters are mainly used for displays of laptops, notebooks, smartphones or other vehicle or aircraft cockpits.

[0006] Holograms are encoded or written into the spatial light modulating device. Such holograms can generally have complex-valued data. In contrast, the spatial light modulating device generally only has a phase modulation or an amplitude modulation of the incident light, so it is designed as a phase modulator or an amplitude modulator, so it does not allow independent modulation of the phase and amplitude of the incident light.

[0007] Therefore, known hologram encoding methods use, for example, a combination of multiple pixels of a spatial light modulating device or two spatial light modulating devices (phase modulator and amplitude modulator) to represent a complex value consisting of amplitude and phase.

[0008] US 2012 / 0092735 A1 discloses a spatial light modulating device in which, for example, the light of multiple phase pixels of a phase modulator is combined by a beam combiner to represent a complex value. In this case, for example, an amplitude value of zero is produced by destructive interference of the light of two phase pixels. However, in such a spatial light modulating device, the contrast of the represented image or scene is adversely affected by errors in the pixel phase modulation.

[0009] In the case of a composite light modulator sandwich structure, in the light path of the display device, amplitude modulators and phase modulators are arranged in succession and combined with each other, so that a complex value per pixel is achieved. This, however, requires that the two spatial light modulation devices are aligned with each other pixel by pixel, which cannot be achieved in a simple manner. In other words, a sandwich structure for complex value modulation can be produced by arranging the individual spatial phase modulators and the individual spatial amplitude modulators with their glass substrates one behind the other. If the light rays from the addressable layer of a pixel of a spatial phase modulator, after passing through the glass substrate, are incident on the addressable layer of a pixel of a spatial amplitude modulator, the light rays have already been spread at the slits of the pixel due to the diffraction effect, with the result that crosstalk of the light rays from adjacent pixels will occur disadvantageously.

[0010] Furthermore, it is known that spatial light modulation devices for various fields of application must or should in general have the following properties: a large number of pixels and small pixel size (i.e. large space-bandwidth product), high modulation speed, high dynamic range, high diffraction efficiency, high precision and reproducible analog or digital control, high fill factor, suitability for light of different spectral ranges and different power densities. These are properties which are difficult to achieve in combination with the use of the above-mentioned light modulation devices.

[0011] US 2016 / 0327906 Al, however, describes a light modulation device designed as a sawtooth light modulator, in which the light repeatedly passes through a single modulation layer of the spatial light modulation device. The modulation layer has phase pixels and amplitude pixels arranged next to each other. By the light passing through the phase pixels and the amplitude pixels in succession in the light path, complex value modulation of the light is achieved. Advantageously, as in the case of a complex sandwich arrangement of spatial light modulation devices consisting of phase modulators and amplitude modulators, the contrast is achieved directly by the amplitude value of the amplitude pixels and not by interference, so that the susceptibility to errors is reduced. Furthermore, the light is modulated in a single layer of the spatial light modulation device, so that the work of aligning the phase pixels and the amplitude pixels with each other, which is the case in a sandwich arrangement of spatial light modulation devices, is eliminated.

[0012] According to US 2016 / 0327906 Al, the effective fill factor of the incident light is reduced due to the fact that the amplitude pixels and the phase pixels are arranged next to each other but are to be passed through in succession in the light path. For example, if the spatial light modulation device is illuminated by a backlight unit (BLU), approximately 50% of the light incident from the backlight unit is lost due to the fact that the phase pixels and the amplitude pixels are arranged next to each other.

[0013] If the phase modulation and the amplitude modulation are based on liquid crystals, it is often necessary to use polarized light. The required polarization of the light with respect to the orientation direction of the liquid crystal molecules (LC) is also typically different for amplitude modulation and phase modulation. This can lead to the need, for example, to rotate the polarization of the light in the optical path between passing through the amplitude pixels and the phase pixels. US 2016 / 0327906 A1 describes the use of a structured retarder to rotate the polarization of the light. It discloses the following: "The light hitting the structured retardation element in the form of a quarter wave plate QWP, which comprises quarter wave plate retardation element segments QWPS 20, introduces a A / 4 retardation for a single pass".

[0014] Figure 1 An arrangement of a spatial light modulating device with a structured retarder or retardation element as disclosed in US 2016 / 0327906 A1 is shown.

[0015] It is apparent that the light is emitted by the illumination unit at a defined angle and is incident on the spatial light modulating device SLM. The light is first incident on the polarization element P1, passes through the polarization element P1 and is incident on the phase pixel p with a defined polarization. At the rear end of the phase pixel p, which introduces a phase shift A mirror element SE is arranged. The light incident on the phase pixel p is reflected back from the mirror element SE, the light passes through the phase pixel again. Subsequently, the light passing through the phase pixel p is twice propagated to a reflection plane RP, which is provided with a structured reflector structure in the form of a mirror element M. The reflection plane RP has a structured retarder in the form of a l / 4 wave plate QWP, which introduces a A / 4 retardation for a single pass of the light. The structured retarder is subdivided into individual segments QWPS arranged on top of the mirror element M. The light is then reflected back from the mirror element M and passes through the retarder QWP again. In this way, a polarization state of the light is generated, which is orthogonal to the incident polarization of the light. The light reflected back from the mirror element M is then incident on the amplitude pixel a. A polarization filter P2 is arranged at the exit plane of the spatial light modulating device. After passing through the spatial light modulating device SLM, the light can be propagated to further elements of the display device (not shown here).

[0016] In other words, according to Figure 1light is obliquely incident from the left onto a spatial light modulator SLM with phase pixels and amplitude pixels. The light passes through a polarization element P1, a slit and a substrate S1 and then impinges in linearly polarized form on a phase pixel p. After passing through the phase pixel p, the light is reflected at a reflective element (mirror element SE), passes again through the phase pixel p, passes back through the substrate S1 and then first impinges on a retarder QWP. Subsequently, the light impinges on a mirror element M, is reflected and passes again through the retarder QWP and then again through the substrate S1 to an amplitude pixel a. Here, the thickness of the substrate S located between the slit or the reflection plane RP and the liquid crystal layer with the amplitude pixel a and the phase pixel p, the angle of incidence a of the collimated light and the pixel pitch of the pixels are coordinated with each other such that, after passing through the substrate S1 and being reflected at the mirror element M, the light beam which impinges on the center of the phase pixel p also impinges on the center of the amplitude pixel a. For example, if the substrate S1 has a thickness d1 and the pixel pitch of a single pixel, i.e. of an amplitude pixel or of a phase pixel, is p1, then the angle of incidence a is set by the illumination device to p1 = 2-d1-tan a. For example, if the thickness d1 of the substrate S1 is 50 micrometers and the pixel pitch is 15 micrometers, then the angle of incidence a will be set to 8.5 degrees. After passing through the amplitude pixel a, the light passes through a second substrate S2 and reaches a polarization filter P2 at the output of the spatial light modulator SLM.

[0017] If light which already has a linear polarization substantially, for example a laser, is used, then the polarization element P1 at the input of the spatial light modulator SLM serves only to further improve the polarization extinction ratio of the light or can also optionally be omitted.

[0018] In the case of use of an ECB (electrically controlled birefringence) mode or a similar liquid crystal mode (LC mode), for example, a quarter-wave plate is used as a retarder, the optical axis of which rotates by about 22.5° with respect to the polarization of the incident light. After two passes through the quarter-wave plate, the polarization direction of the light is rotated by 45°. In this case, however, the retarder must be structured. A further structured layer, namely a mirror, must be applied to the retarder. However, since the retarder is usually an organic layer, the structuring of the retarder can be significantly more complex than the structuring of a metal layer, for example a mirror.

[0019] However, the use of a structured retarder or retardation element in a spatial light modulator is complex to produce and requires precise alignment of the retarder with respect to the pixels of the spatial light modulator. Furthermore, in order to avoid diffraction effects, the position of the retarder should be very close to the modulation layer of the spatial light modulator. US 2016 / 0327906 A1 describes the use of polarized light and a structured retarder, but does not specify any details regarding the polarization direction of the light used, the orientation of the retarder axis and the type of liquid crystal modulation.

[0020] Furthermore, the use of small-sized pixels in a spatial light modulating device is advantageous for a holographic display or display device. In particular, for a holographic display having at least one virtual viewing window through which an observer in an observer plane can view a represented scene, the size of the virtual viewing window is proportional to the pitch of the complex-valued macro-pixels formed here from amplitude pixels and phase pixels, i.e. the sum of the pitches of the amplitude pixels and the phase pixels.

[0021] For example, a typical value for the desktop display macro-pixel pitch is 30 x 30 micrometers. For a complex sandwich structure consisting of multiple layers according to the prior art, as described above with regard to the sandwich structure arrangement of the spatial light modulating device, this would mean that also the individual pixels of the spatial light modulating device can have this size. However, for a spatial light modulating device comprising a single layer in which amplitude pixels and phase pixels are arranged next to each other, this means that the size of the amplitude pixels and the phase pixels would be 15 x 30 micrometers, respectively.

[0022] However, for a transmissive active matrix display having a matrix of thin film transistors for driving the pixels, the available pixel area is typically reduced due to the area occupied by the transistors (TFTs) of the pixels themselves and the data lines conducting the electrical signals from the display edge region to the pixels. A "black mask" is typically used to cover or blacken the area of the transistors and lines so that light not modulated in the prescribed manner cannot pass through these areas. Due to production requirements, the black mask is typically not arranged on the backplane substrate where the transistors and data lines are arranged, but on a substrate opposite to the backplane substrate, so that both substrates have to be aligned to each other so that the resulting tolerances can be accepted. However, this is typically not easy and time-consuming.

[0023] Typically, about 5 x 10 micrometers (horizontal x vertical) of the area or edge of the pixel is covered by the black mask and has to be subtracted from the pixel. For example, assuming a pixel size of 30 x 30 micrometers, an area of 25 x 20 micrometers is actually available as a pixel aperture, which corresponds to an area proportion of 55%.

[0024] For a pixel that is half as large in size, 15 x 30 micrometers, only an area of 10 x 20 micrometers is available as an aperture, which corresponds to an area proportion of only 44%.

[0025] Due to the absorption of a portion of the incident light by the black mask, the reduction of the pixel aperture size results in a reduction of the light efficiency of the spatial light modulating device. Furthermore, for smaller pixel apertures, the diffraction of the light also increases, so that the undesired cross-talk of the light between the pixels also increases, in which case, for example, light that is actually intended to first be incident on the phase pixel is directly incident on the amplitude pixel.

[0026] As already mentioned, the diffraction effect occurs at the slits or openings of the spatial light modulator device. Disadvantageously, light diffracted at the input-side slits can thus not be incident on the desired pixel (e.g. phase pixel) but on an adjacent pixel (e.g. amplitude pixel) which then exits the spatial light modulator device virtually only once modulated, i.e. only amplitude modulated or only phase modulated.

[0027] US 2016 / 0327906 A1 has mentioned that light diffracted at the input-side slits can advantageously be blocked by an output-side polarizer. However, US 2016 / 0327906 A1 gives no indication as to how this polarizer should be oriented. Since amplitude modulation of the light generally requires a specific setting of the output-side polarizer, this setting cannot be chosen independently of the setting for optimal suppression of the diffracted light.

[0028] It is therefore an object of the present application to provide and further develop a spatial light modulator device for complex-valued modulation of light according to US 2016 / 0327906 A1 in order to achieve, in particular, a higher light efficiency and a simpler production.

[0029] Furthermore, it is an object of the present application to provide a spatial light modulator device which enables an increase in the fill factor.

[0030] The present application is further based on the object of providing a spatial light modulator device which enables a reduction and, in most cases, avoidance of light crosstalk between adjacent pixels of the spatial light modulator device.

[0031] According to the application, this object is achieved by a spatial light modulator device having the features of claim 1.

[0032] The spatial light modulator device according to the application has modulation elements in the form of pixels. The spatial light modulator device is designed substantially half of the pixels as reflective pixels and the other half of the pixels as transmissive pixels. The reflective pixels are arranged alternately with the transmissive pixels in the same or the same substrate plane of the spatial light modulator device. Furthermore, the spatial light modulator device comprises a backplane which comprises transistors and data lines for conducting signals to the pixels. Each pixel is assigned at least one transistor and at least two data lines. The transistor and the data lines of each pixel pair consisting of an adjacent reflective pixel and a transmissive pixel are arranged below the reflective pixel (in the direction of light propagation).

[0033] Advantageously, the spatial light modulation device comprises at least one transparent substrate and an addressable transmissive layer, which is preferably designed as a liquid crystal layer containing liquid crystal molecules and forms the pixels as modulation elements for modulating the incident light. Preferably, two substrates are provided, the addressable transmissive layer being embedded between the two substrates. Thus, the addressable transmissive layer, which can be designed as a liquid crystal layer, forms the pixels of the spatial light modulation device, which are capable of modulating the phase and amplitude of the incident light. According to the present application, the spatial light modulation device has only a single addressable transmissive layer or liquid crystal layer. Thus, the phase and amplitude of the light are modulated in adjacent pixels of the spatial light modulation device. This means that phase pixels and amplitude pixels are arranged or disposed in the same substrate plane in an alternating or alternating manner. In this way, the incident light passes through the phase pixels and the amplitude pixels in succession in the direction of light propagation. In principle, the order of the modulation of the amplitude and phase of the light can also be reversed. However, with regard to the liquid crystal modulation, it is generally more advantageous that the light passes through the phase pixels twice due to the reflection and only once through the amplitude pixels. In other words, there are reflective and transmissive pixels in the spatial light modulation device. Preferably, the phase pixels are designed as reflective pixels and the amplitude pixels are designed as transmissive pixels. By means of the electrodes on the substrate, the pixels can be controlled in a defined manner and the liquid crystal molecules of the liquid crystal layer can be aligned, preferably as an addressable transmissive layer. Furthermore, the spatial light modulation device according to the present application comprises a backplane with transistors and data lines, and even more elements, such as storage capacitors, however, these elements have no further relevance to the present application and are provided for controlling the spatial light modulation device. Each pixel, i.e. each phase pixel and each amplitude pixel, is assigned at least one transistor and at least two data lines. According to the present application, at least a part of the transistors and data lines of each adjacent pixel pair consisting of a reflective pixel and a transmissive pixel is arranged below or behind the reflective pixel of the pixel pair.

[0034] Since substantially half of the pixels, i.e. the phase pixels or the amplitude pixels, are designed as reflective pixels, the light does not pass through or penetrate the backplane with the transistors and data lines for the respective reflective pixel. According to the present application, the transistors and data lines, at least a part of the data lines, of each pixel pair consisting of a reflective pixel and a transmissive pixel can thus be arranged below the reflective pixel associated with the pixel pair, so that the aperture of the transmissive pixel is no longer reduced due to the at least one transistor associated with the pixel and at least a part of the data lines associated with the pixel. This means that, advantageously, the phase pixels are designed as reflective pixels and the amplitude pixels are designed as transmissive pixels, the transistors and data lines of each pixel pair consisting of a phase pixel and an amplitude pixel being arranged below the phase pixel designed as a reflective pixel associated with the pixel pair.

[0035] In this way, by providing transmissive and reflective pixels and the arrangement of at least a portion of the transistors and data lines according to the application, the configuration of the spatial light modulating device according to the application, the pixel aperture is significantly increased and the fill factor is significantly increased. Moreover, since the spatial light modulating device according to the application achieves a high light efficiency, the diffraction of light is minimized, thereby significantly reducing or avoiding undesired cross-talk between light from adjacent pixels.

[0036] For the sake of illustrating the application, it is assumed that the reflective pixels are designed as phase pixels and the transmissive pixels are designed as amplitude pixels, the light first passes through the phase pixels and then through the amplitude pixels. Of course, the light can also first pass through the amplitude pixels.

[0037] Further advantageous configurations and developments of the application are apparent from the further dependent claims.

[0038] In a particularly advantageous configuration of the application, the reflective pixels can be provided with a reflective layer, preferably a mirror element, the reflective layer being arranged at the rear end of the reflective pixel in the direction of light propagation. In the case of the use of a backlight device in the display device, this configuration of the spatial light modulating device according to the application can be preferred, such that the light, which is preferably incident first on the phase pixel, is reflected in the direction of the reflective plane downstream in the direction of light propagation and from said reflective plane to the amplitude pixel. Thus, a sawtooth-shaped light beam is generated inside the spatial light modulating device.

[0039] In another advantageous configuration of the application, the backplane can be provided with a black mask assigned to the transistors and data lines, the black mask being configured such that the black mask does not cover or obscure the edge region of the aperture of the pixel over the entire extension. The pixel can be designed in a rectangular manner, for example, the aperture of the pixel is limited on two opposite sides and is not limited on the other two opposite sides. Of course, the pixel can also have a different shape, for example, circular or hexagonal.

[0040] The backplane has a black mask assigned to the transistors and data lines of the pixels. Usually, the pixels are designed in a rectangular fashion and arranged in a matrix in the form of columns and rows. The pixels are individually addressed and controlled by the transistors. Therefore, the data lines are arranged horizontally and vertically and connected to the individual transistors of the pixels in this way. In order to prevent light that is not modulated in the prescribed manner from penetrating this area of the backplane equipped with transistors and data lines, a black mask is provided which covers or conceals this area of the transistors and data lines. In the case of this matrix-like arrangement of the pixels in rows and columns and the assigned vertical and horizontal data lines, the concealment of the vertical data lines by the black mask as in the prior art can be omitted since the black mask can simply be arranged simultaneously under the reflective pixels. Because, now, due to the reflective pixels and at least a portion of the transistors and data lines arranged under the reflective pixels, the area equipped with transistors and data lines and reduced pixel gap is significantly reduced compared to the spatial light modulator of the prior art, in particular for transmissive pixels, a larger pixel area can be used to modulate the light. Thus, the available fill factor of the spatial light modulator according to the present application is increased. Furthermore, now only the data lines that are not arranged under the reflective pixels need to be assigned a black mask and these data lines, e.g. the horizontal data lines, need to be concealed by the black mask. Compared to when the transistors and data lines cannot be arranged under the reflective pixels, the proportion of data lines that now have to be concealed by the black mask is much smaller. The problem of alignment tolerances is thereby reduced.

[0041] Advantageously, one side of the at least one transparent substrate can be provided with an addressable transmissive layer comprising the pixels, the other opposite side can be provided with a plane designed as a reflective plane.

[0042] The light entering the spatial light modulation device then passes through both the reflective and the transmissive pixels, the light being reflected between the two by a reflecting plane. In this way, light can pass through both the reflective and the transmissive pixels, which are located on one plane. As a result, a combined phase and amplitude pixel (combined reflective and transmissive pixel) of the spatial light modulation device is provided in order to realize a complex-valued spatial light modulation device. In other words, a phase pixel and an amplitude pixel are combined next to or adjacent to each other. The spatial light modulation device has an addressable transmissive layer for forming the pixels. The addressable transmissive layer can be a liquid crystal layer. However, other discrete implementations of the spatial light modulation device are also possible, for example, an electrically woven-based spatial light modulation device or a magneto-photonic crystal-based spatial light modulation device. The liquid crystal thickness of such an addressable transmissive layer required for a 2π phase modulation of the phase pixel is typically twice the liquid crystal thickness required for the amplitude modulation of the amplitude pixel. In the case of the present invention, the liquid crystal layer thickness of the amplitude pixel can be equal to the liquid crystal layer thickness of the phase pixel. This can preferably be realized by implementing a double-pass arrangement of the phase pixel. By using a reflecting plane provided at one side of the spatial light modulation device, a deflection of the light passing through the first pixel (phase pixel or amplitude pixel or reflective pixel or transmissive pixel) is introduced.

[0043] Thus, a display device for holographic reconstruction of a scene according to the present invention can be provided, which has a flat structure and allows to realize a complex light modulation.

[0044] According to the present invention, the reflecting plane can further be provided to comprise a mirror system at which the light is reflected between the reflective and the transmissive pixel. The mirror system can comprise mirror elements.

[0045] Thus, the mirror system can advantageously comprise mirror elements which are designed to have reflectivity at the side facing the addressable transmissive layer having the pixels or which are designed to have reflectivity at both sides, at the side facing the addressable transmissive layer having the pixels and at the side facing away from the addressable transmissive layer having the pixels.

[0046] If a mirror system is provided which comprises mirror elements designed to have reflectivity only at the side facing the addressable transmissive layer having the pixels, a spatial light modulation device can be provided which allows a light beam incident on the entrance plane of the spatial light modulation device to be directed preferably to a reflective pixel, preferably designed as a phase pixel, and to be phase-modulated by this reflective or phase pixel. The light beam is then reflected on the reflective layer of the reflective pixel and further directed to a respective mirror element of the mirror system in the reflecting plane, the light beam is reflected on the mirror element and guided or directed to a transmissive pixel, preferably designed as an amplitude pixel. The amplitude pixel modulates the intensity of the incident light, the light then exits the spatial light modulation device in the direction of the observer region of the reconstructed scene.

[0047] In contrast, if the arrangement comprises a mirror system designed with mirror elements that are reflective on both sides towards the side with the addressable transmissive layer with pixels and away from the side with the addressable transmissive layer with pixels, the light intensity or light efficiency of the spatial light modulator can thus be increased. For modulating light using two adjacent arranged pixels (reflective and transmissive or phase and amplitude) of the spatial light modulator, which involves a continuous passage of these pixels in the light path, it is necessary to block a part of the incident light at the input side of the spatial light modulator, so that the light is incident and directed only in the direction of the reflective or phase pixels and reaches the amplitude pixels only after passing the phase pixels. However, in arrangements according to the prior art, for example according to US 2016 / 0327906 Al, this light would be completely lost, so that the light efficiency of the spatial light modulator is adversely affected and thus reduced.

[0048] According to the present application, the mirror elements of the mirror system for reflection between the phase and amplitude pixels can be designed such that they not only have a reflective effect or act as mirrors on the inner side, i.e. towards the modulating transmissive layer or preferably the liquid crystal layer, but also reflect the light at or on the input side of the spatial light modulator.

[0049] For this purpose, it can be advantageous if the mirror elements of the mirror system are arranged with respect to the reflective and transmissive pixels such that each mirror element covers a part of the reflective pixels and a part of the transmissive pixels.

[0050] In this way, the light can preferably be guided from the phase / amplitude pixels via the mirror system in a zigzag shape to the amplitude / phase pixels of the spatial light modulator, so that the amplitude and phase pixels can be arranged in the same plane of the spatial light modulator.

[0051] It is therefore advantageous if the addressable transmissive layer can be arranged to be coupled to the reflective plane such that the incident light passes through both the reflective and transmissive pixels of the addressable transmissive layer, the light being reflected between the two by the reflective plane.

[0052] In a further advantageous configuration of the present application, an unstructured retardation element can be provided.

[0053] It is particularly advantageous if, in this case, the unstructured retardation element can be arranged in the reflective plane and can be configured to set the polarization of the incident light for the second passing pixel of an adjacent pixel pair consisting of a reflective and a transmissive pixel (the reflective and transmissive pixels being designed as phase and amplitude pixels and together forming a composite pixel pair or macro pixel) when the light passes through the pixel pair.

[0054] According to the invention, the spatial light modulation device comprises a region (i.e. unstructured or chaotically structured) retardation element which can be arranged in the reflection plane. The unstructured retardation element is provided in order to appropriately set the polarization of the light for the second pixel to pass between the corresponding two pixels (phase pixel and amplitude pixel). The reflective pixel (preferably the phase pixel) and the transmissive pixel (preferably the amplitude pixel) form a composite pixel pair or macro pixel.

[0055] By using an unstructured retardation element, the production of the spatial light modulation device can be significantly simplified, since the region or unstructured retardation element no longer needs to be aligned with the mirror elements of the mirror system in the reflection plane as is the case with the structured retarders of the prior art. Since a structured layer (i.e. a mirror system comprising mirror elements) has to be applied on the retardation element, the unstructured retardation element now allows a simpler implementation of the production process in a more time-saving manner. Furthermore, the retardation element (also referred to as retarder) is usually an organic layer which cannot be produced using semiconductor processes (e.g. mirror layers). Therefore, the structuring of the retardation element and the exact alignment with the mirror elements provided thereon can be avoided or circumvented.

[0056] The unstructured retardation element can be designed as a quarter-wave plate or an eighth-wave plate.

[0057] According to the invention, a compensating retardation element can also be provided.

[0058] To this end, it is advantageous if the compensating retardation element can be unstructured and can be designed as a quarter-wave plate or an eighth-wave plate, the compensating retardation element interacting with the unstructured retardation element such that the light incident on the first pixel to pass in the composite pixel pair or macro pixel has the required polarization.

[0059] The spatial light modulation device according to the invention can have a compensating retardation element, also referred to as compensating retarder, which can likewise be unstructured. The compensating retardation element is arranged in the spatial light modulation device such that the incident light passes through it upstream of the corresponding two pixels of the addressable transmissive layer in the direction of light propagation, the compensating retardation element appropriately setting the polarization of the light for the first pixel to pass.

[0060] Both delay elements, i.e. the unstructured delay element and the compensating delay element, act on the light incident thereon, thereby changing the polarization of the light. This means that the light incident on the spatial light modulation device according to the application has already passed the unstructured delay element before reaching the first pixel, e.g. a phase pixel, of the addressable transmissive layer to be passed, since the reflection plane of the unstructured delay element is arranged upstream of the addressable transmissive layer in the direction of light propagation in case of a backlit arrangement. In case of a front light illumination of the addressable transmissive layer of the spatial light modulation device, the reflection plane is located downstream of the addressable transmissive layer in the direction of light propagation. For example, if the light is to pass a phase pixel of the addressable transmissive layer first, in case of an ECB (electrically controlled birefringence) mode, the phase pixel requires linearly polarized light, the illumination device emits light or the light emitted by the illumination device is converted into linearly polarized light by a polarizer. The unstructured delay element then converts the linearly polarized light incident thereon into circular light. In order to cancel or compensate for this conversion of the light polarization, a compensating delay element can be provided, which is also designed in an unstructured manner, such that the combination of both delay elements acts on the incident light and thereby again generates linearly polarized light.

[0061] The unstructured delay element and the compensating delay element can have the same optical axis direction or their optical axes can be rotated by 90° with respect to each other.

[0062] Advantageously, two polarizers can be provided, one polarizer can be arranged in the light entry plane area of the light modulation device and the other polarizer can be arranged in the light exit plane area of the light modulation device.

[0063] For example, the polarizer arranged at the input side of the spatial light modulation device or in the light entry plane area of the spatial light modulation device can be rotated by 45° with respect to the required polarization at the phase pixel and the unstructured delay element and the compensating delay element can have the same optical axis of about 22.5° such that they together act as a half wave plate (1 / 2 wave plate). In this way, the polarization direction of the light can be rotated by 45° and thus the light will be incident at the phase pixel with the required polarization. Alternatively, the unstructured delay element and the compensating element can have optical axes which are rotated by 90° with respect to each other, the result of which is that their effects cancel each other out in total.

[0064] In another advantageous configuration of the application, the polarizer arranged in the light entry plane area of the light modulation device can be arranged to be designed as a transmissive polarizer for one specified polarization and as a reflective polarizer for another specified polarization and is preferably designed as a wire grid polarizer. In this scenario, a polarizer designed as a reflective polarizer means that light having a specific (e.g. linear) polarization is reflected at the polarizer. However, in addition, light having another (e.g. also linear) polarization can also be transmitted through the polarizer. For example, a wire grid polarizer reflects s-polarized light and transmits p-polarized light.

[0065] In order to further increase the light intensity of the spatial light modulation device, in conjunction with an embodiment of the mirror element of the mirror system, which is designed to have reflectivity on both sides, the polarizer arranged in the light entry plane area of the spatial light modulation device can be designed as a reflective polarizer. The optical axis of the compensating retardation element is aligned here with the mirror element of the mirror system, which is designed to have reflectivity on the side facing the addressable transmissive layer and on the side facing away from the addressable transmissive layer, the retardation element or retarder designed for light recirculation, and the polarizer arranged in the light entry plane area of the spatial light modulation device can be selected in such a way that the degree of polarization of the light reflected by the mirror element of the mirror system on the input side and directed back to the polarizer arranged in the input side or the light entry plane is rotated. Thus, all or at least a part of the light is reflected by the polarizer arranged in the light entry plane and is thus oriented or directed again in the direction of the pixels and can continue to be used.

[0066] The polarizer arranged in the light entry plane area can be designed as a wire grid polarizer. For example, the p-polarized light from the illumination unit is then transmitted by the wire grid polarizer. The s-polarized part of the light reflected by the mirror element in the reflection plane and directed back to the polarizer is then reflected at the polarizer.

[0067] In addition, the distance between the polarizer arranged in the light entry plane area of the light modulation device and the mirror element of the mirror system in the reflection plane can be set to the same value as the thickness of the at least one substrate between the mirror element of the mirror system and the addressable transmissive layer having the pixels.

[0068] By setting the distance between the polarizer arranged in the light entry plane area and the mirror element of the mirror system to a value that is approximately or almost the same as the substrate thickness between the mirror element of the mirror system and the addressable transmissive layer, it is achieved that, after reflection of the light at the polarizer arranged on the input side, the light reaches the openings or slits of the addressable transmissive layer and no longer impinges on the mirror element of the mirror system.

[0069] The orientation of the liquid crystal molecules of the pixels can be arranged to rotate the orientation of the liquid crystal molecules of the transmissive pixels by 45° with respect to the orientation of the liquid crystal molecules of the reflective pixels.

[0070] In one particular embodiment of the spatial light modulation device, a structured alignment or a structured orientation of the liquid crystal molecules of the liquid crystal layer, which is an addressable transmissive layer, can be provided as amplitude pixels and phase pixels. By optical alignment, the liquid crystal molecules in the amplitude pixels can be aligned and arranged in a manner rotated by 45° compared to the liquid crystal molecules in the phase pixels. For example, in the case of ECB mode and similar liquid crystal modes, this has the advantage that the polarization of the light between the amplitude pixels and the phase pixels either does not need to be rotated at all or can be rotated by 90°.

[0071] In the first case, without a polarization rotation of the light being provided, therefore, an unstructured retardation element between the amplitude pixels and the phase pixels is avoided. In the second case, if a 90° polarization rotation of the light is provided, the unstructured retardation element can be configured with its optical axis provided at approximately 45°.

[0072] According to the application, the polarizer provided in the light exit plane area of the light modulation device can also be provided with a polarization direction that is rotated by 90° with respect to the polarization direction of the light incident on the first pixel of the pixel pair consisting of the reflective pixel and the transmissive pixel when the light passes through the pixel pair.

[0073] If a structured alignment of the liquid crystal in the liquid crystal layer is used in the amplitude pixels and the phase pixels, in which the orientation of the liquid crystal molecules in the amplitude pixels is rotated by 45° with respect to the orientation of the liquid crystal molecules in the phase pixels, the polarization of the light between the amplitude pixels and the phase pixels can not be rotated, i.e. no unstructured retardation element or unstructured retarder is used. Furthermore, the output-side polarizer provided in the exit plane area of the spatial light modulation device can be used in a manner rotated by 90° with respect to the polarization of the light incident on the phase pixel, for example, as the first pixel of the pixel pair. In this case, the light directly incident on the amplitude pixel adjacent to the phase pixel due to the diffraction at the slit in the reflective plane will not be phase-modulated, but will likewise be amplitude-modulated. Therefore, the portion of the light transmitted by the polarizer provided in the light exit plane area of the spatial light modulation device is proportional to the amplitude of the pixel, i.e. the greater the absorption portion of the light, the smaller the amplitude of the pixel. This case is particularly advantageous for the effect that the pixel crosstalk due to the diffraction in this case does not have a disturbing influence on the contrast. Pixels that are represented as black and have an amplitude value equal to zero are actually still black, since for these pixels the diffracted light is completely filtered or absorbed.

[0074] Generally, this means that according to the application, the undesired diffracted light incident in each case on a pixel adjacent to the pixel whose light is to be modulated can be filtered by the polarizer arranged in the light exit plane area of the light modulating device. Preferably, the undesired diffracted light incident in each case on a pixel adjacent to the pixel whose light is to be modulated can be arranged to be filtered by the polarizer arranged in the light exit plane area of the light modulating device, depending on the amplitude value of the adjacent pixel.

[0075] Furthermore, it is advantageous that a color filter device having color filters of the primary colors RGB can be provided, the individual color filters being assigned alternately to the pixels.

[0076] Since the light passes successively through the amplitude pixel and the phase pixel in the direction of light propagation, it is basically sufficient for the color representation of a scene or object for either the phase pixel or the amplitude pixel to have a color filter. However, in order to reduce crosstalk, it is advantageous for both the amplitude pixel and the phase pixel to have a color filter. By way of example, the color filters can be arranged as vertical strips of the color filter device, such that the colors comprise in each case a (double) column of amplitude pixels and phase pixels arranged next to one another. The amplitude pixels and phase pixels in the (double) column located above or below the composite pixel pair consisting of an amplitude pixel and a phase pixel are assigned the same color filter, but the amplitude pixels and phase pixels located to the left or right of said pixel pair, i.e. assigned to another (double) column, are assigned another color filter.

[0077] Thus, advantageously, a composite pixel pair consisting of a reflective pixel and a transmissive pixel can be provided with color filters of the same color, and adjacent composite pixel pairs consisting of a reflective pixel and a transmissive pixel have color filters of different colors. Thus, both pixels of a composite pixel pair, i.e. the reflective pixel and the transmissive pixel, can each have a color filter of the same color. Alternatively, both pixels of a pixel pair have jointly only one color filter of one color, or only one color filter is assigned to both pixels of a pixel pair.

[0078] The use of color filters in the spatial light modulating device can also result in a reduction of crosstalk between the pixels due to the diffraction of light. If the spatial light modulating device is illuminated with light of a defined wavelength, light of an adjacent pixel or composite pixel pair which is assigned a color filter of another color is blocked by this color filter.

[0079] According to the application, the spatial light modulating device can be designed as a liquid crystal (LC) based spatial light modulating device, or as a multiple quantum well (MQW) based spatial light modulating device.

[0080] Of course, other light modulator configurations can also be employed.

[0081] For example, the spatial light modulation device according to the present application can be an electrically woven based spatial light modulation device for providing amplitude modulation and / or phase modulation.

[0082] Furthermore, the spatial light modulation device can be designed as a multiple quantum well (also referred to as multi-quantum well) (MQW) based device. This type of modulator can work in reflection or transmission, can be configured to modulate amplitude and / or phase. In general, the principle of serial combination of adjacent phase and amplitude pixels can also apply to non-liquid crystal based phase and amplitude modulators. By way of example, a magneto-photonic crystal (MPC) based spatial light modulation device can be used.

[0083] Furthermore, the object according to the present application is achieved by a display device having the features according to claim 29.

[0084] The display device according to the present application comprises an illumination device and a spatial light modulation device according to the present application. The illumination device can comprise at least one light source, for example a laser light source or a light emitting diode (LED). The display device according to the present application is used for holographic reconstruction of a scene or an object, preferably for displaying two-dimensional and / or three-dimensional images or content or information. The display device comprises a spatial light modulation device according to the present application, which comprises combined reflective and transmissive pixels designed as phase pixels and amplitude pixels. The illumination device is configured for illuminating the spatial light modulation device. In this way, the combined phase and amplitude pixels of the display panel are arranged so as to achieve a complex-valued display device.

[0085] Thus, a display device for holographic reconstruction of a scene is provided, which has a flat structure and allows to achieve complex light modulation.

[0086] The display device comprising these basic components can be equipped with further optical components, or the existing components can be arranged differently, for example in a way that a transmissive or reflective spatial light modulation device is created. In the case of a reflective spatial light modulation device, then a reflective plane is arranged downstream of the addressable transmissive layer in the direction of light, at which the incident light is reflected.

[0087] Advantageously, the illumination device can be arranged to provide oblique illumination of the light modulation device.

[0088] It can be preferred to use oblique or slanted illumination of the spatial light modulation device. By way of example, an illumination of the spatial light modulation device of 5° to 50°, preferably 5° to 20°, can be used. For a variety of liquid crystal modes, an angle range of 5° to 20° can be advantageous. For example, certain liquid crystal modes can also be illuminated at an angle of 45°. The oblique illumination can be provided by a variety of types of illumination devices. However, an illumination device based on volume gratings is preferred. This is due to the angular and spectral selectivity of the volume gratings based on Bragg diffraction.

[0089] The illumination device can be designed as a front-lighting illumination device or as a back-lighting illumination device.

[0090] By way of example, the display device according to the application can have a field lens as a further component, which is designed as a single component or as a combined field lens. The field lens can be designed as a diffractive lens or as a refractive lens. If the field lens is designed as a diffractive lens, it can have at least one volume grating. The combined field lens can preferably have at least one volume grating.

[0091] The display device comprises a field lens for focusing the light modulated by the spatial light modulating device with the desired information to a defined area or a defined position in the visual range or field of view of an observer who can observe the scene or object represented by the display device. The field lens can be provided as a separate component or as a single component or as a combined field lens in the display device. By way of example, the complex spatial light modulating device according to the application can also be used in a volume grating-based field lens used in the display device according to the application. To this end, the combined volume grating field lens has a first volume grating, which implements a plane-to-plane reconstruction, which can be, for example, a 0° (on-axis) to 30° tilted incidence plane wave. A second volume grating has a reconstruction of a 30° plane wave with respect to the on-axis field lens. The combination of the two volume gratings forms an on-axis volume grating field lens, which is referred to as a combined field lens.

[0092] Preferably, the first volume grating of the combined field lens can be eliminated using tilted incidence or oblique illumination, which leads to an off-axis propagation of the complex light. For example, an SLM plane with phase-modulated pixels and amplitude-modulated pixels to be combined can be illuminated at an angle of 30°, which leads to an off-axis propagation of -30° of the modulated wave field. As a result, the previously used pre- diffusion volume grating as a first element of the combined field lens is no longer required. This makes it possible to reduce the number of components used.

[0093] In a further advantageous configuration of the application, at least one tracking device can also be provided. Advantageously, the at least one tracking device can comprise at least one liquid crystal grating and / or at least one mirror element.

[0094] The display device according to the application can comprise at least one tracking device, for example a vertical tracking device for tracking the light in the vertical direction and / or a horizontal tracking device for tracking the light in the horizontal direction, which vertical tracking device and / or horizontal tracking device preferably has at least one liquid crystal grating.

[0095] The vertical tracking device and / or the horizontal tracking device are preferably arranged downstream of the complex spatial light modulating device in the direction of light propagation for tracking the light of the represented scene or object with respect to vertical and / or horizontal movements of an observer observing the scene or object.

[0096] Preferably, at least one tracking device includes at least one liquid crystal grating. For example, a liquid crystal grating electrically controlled by electrodes can generate a one-dimensional phase profile. These controllable one-dimensional phase profiles can provide a wedge-shaped function suitable for tracking light sent to an observer's eye. Furthermore, cylindrical phase functions can be generated. Thus, in addition to setting up tracking by generating different grating periods and different local phase tilt angles, cylindrical lens functions can also be generated, which reduce the aberrations of tilt lens functions. Multiple liquid crystal gratings can be used in series. Thus, for example, two liquid crystal gratings with an angular offset of 90° can be stacked or arranged one on top of the other.

[0097] Then, if possible, there are various advantageous configurations of the teachings of the invention and / or combinations of the described exemplary embodiments or configurations with each other. For this purpose, reference should first be made to the patent claims dependent on the alternative independent patent claims, and secondly to the following explanation of preferred exemplary embodiments of the invention with reference to the accompanying drawings, in which the general preferred configuration of the teachings is also explained. In this context, the basic principles of the invention are explained based on the described exemplary embodiments, but are not intended to be limited thereto.

[0098] The attached diagram shows:

[0099] Figure 1 A schematic diagram of a spatial light modulation device according to the prior art is shown;

[0100] Figure 2 A top-view schematic diagram showing details of the pixel arrangement of a spatial light modulation device according to the prior art;

[0101] Figure 3 A top-view schematic diagram showing details of the pixel arrangement of the spatial light modulation device according to the present invention is shown;

[0102] Figure 4a A top schematic diagram of a spatial light modulation apparatus with an unstructured delay element according to the present invention is shown;

[0103] Figures 4b to 4d It shows according to Figure 4a A perspective schematic diagram of an embodiment of a spatial light modulation device (in which "pol" indicates polarization);

[0104] Figure 5 A schematic diagram of another embodiment of a spatial light modulation apparatus for setting up light recirculation according to the present invention is shown;

[0105] Figure 6 This shows the setting of in-plane mode and Figure 5 A schematic diagram of the corresponding spatial light modulation device;

[0106] Figure 7 shows a schematic diagram of the pixel arrangement of a spatial light modulation device with an unstructured arrangement of liquid crystal molecules;

[0107] Figure 8 A schematic diagram of the pixel arrangement of a spatial light modulation device with a structured arrangement of liquid crystal molecules is shown;

[0108] Figure 9 A schematic diagram of another configuration of a spatial light modulation apparatus for reducing crosstalk between adjacent pixels according to the present invention is shown; and

[0109] Figure 10 A schematic diagram of a display device according to the present invention, including a spatial light modulation device according to the present invention, is shown.

[0110] It should be briefly mentioned that the same elements / structural parts / assemblies may have the same reference numerals in the accompanying drawings.

[0111] exist Figure 2 The top view shows a basic configuration of a spatial light modulation device according to the prior art, showing only the pixel arrangement combined with the backplane. In the spatial light modulation device, a serial combination of phase pixels Pp and amplitude pixels Ap arranged laterally adjacent to each other in the same addressable transmissive layer or layer plane is provided. For example, the addressable transmissive layer used to form complex-valued pixels is preferably a liquid crystal layer. As can be seen, the phase pixels Pp and amplitude pixels Ap are therefore arranged adjacent to each other. Overall, in the spatial light modulation device, approximately 50% of the panel area is used for non-transparent structures, such as data lines and transistor structures arranged in the backplane.

[0112] like Figure 2 As can be seen, pixels are arranged in columns and rows in a matrix. Pixels are individually addressed from the backplane via transistor TFTs connected to vertical and horizontal data lines D. The transistor TFTs of pixels Pp and Ap are controlled by the data lines D (i.e., the so-called source and gate lines) arranged in the columns and rows. The transistor TFTs and data lines are configured to transmit signals to the individual pixels. The spatial light modulation device also has a black mask BM, which covers the panel area allocated to the data lines D and transistor TFTs of the backplane. The black mask BM is typically disposed on the substrate of the spatial light modulation device opposite the substrate of the backplane. In this way, the area of ​​the substrate allocated to the data lines D and transistor TFTs becomes black, so that no light can penetrate these areas of the spatial light modulation device.

[0113] Light incident on the spatial light modulation device first passes through the phase pixels Pp and then through the amplitude pixels Ap, or vice versa. In this case, however, the pixel gap is significantly reduced due to the associated transistors TFT arranged in each pixel Pp and Ap and due to the horizontal data lines D and vertical data lines D also passing through the pixels Pp and Ap. The transistors TFT and data lines D are thus completely covered by the black mask BM, which is slightly wider than the data lines D together with the transistors TFT themselves due to the alignment tolerances of the two substrates on which the black mask BM, the transistors TFT and the data lines D are arranged. The gap of the respective pixel Pp or Ap through which light should and can pass is thus significantly reduced by the transistors TFT, the data lines D and the black mask, in particular for small-sized pixels.

[0114] In contrast, Figure 3 A spatial light modulation device is shown, which, according to the present application, achieves or has a greater gap of the pixels Pp and Ap due to the specific arrangement of the transistors and data lines.

[0115] Figure 3 A top view of a spatial light modulation device according to the present application is shown, which has the same elements or components as the spatial light modulation device according to Figure 2 in terms of the basic setup. This means that the spatial light modulation device comprises an addressable transmissive substrate, which is preferably designed as a liquid crystal layer. The addressable transmissive layer forms a pixel layer with the pixels Pp and Ap and is embedded between two substrates. The pixel layer has phase pixels Pp and amplitude pixels Ap arranged alternately in one plane. Substantially half of the pixels of the addressable transmissive layer or pixel layer are designed as reflective pixels and the other half as transmissive pixels, so that reflective pixels and transmissive pixels are arranged alternately in the same plane. In the present exemplary embodiment, the phase pixels are designed as reflective pixels and the amplitude pixels as transmissive pixels, it is of course also possible that the amplitude pixels are designed as reflective pixels and the phase pixels as transmissive pixels. The phase pixels Pp form a composite pixel pair together with the amplitude pixel Ap adjacent thereto.

[0116] In this exemplary embodiment, the light coming from the illumination device and incident on the spatial light modulator device (in the following SLM) is now first incident on the phase pixels Pp designed as reflective pixels and reflected by the phase pixels Pp through a reflective layer provided at the phase pixels Pp, which can be designed as mirror elements. In this case, the reflective layer is provided at the back end of the reflective pixel, here the phase pixel Pp, in the direction of light propagation, so that the light passes through the phase pixel Pp, is incident on the reflective layer, is reflected by the reflective layer and passes through the phase pixel again. In this case, the phase of the light is modulated, changed or adjusted in accordance with the required information. After passing through the phase pixel, the light is further directed via the reflective plane in the direction of the transmissive pixel, i.e. here the amplitude pixel Ap, and passes through the transmissive pixel in order to be subjected to the corresponding amplitude modulation. As can be seen, Figure 2 and Figure 3 the slit of the pixels in Figure 3 the pixels Pp and Ap in Figure 2 have a relatively large difference. Figure 3 the fill factor of the SLM in Figure 2 is significantly larger than the fill factor of the SLM in Figure 3 The larger slit of the pixels Pp and Ap or the larger fill factor is actually achieved by the fact that substantially half of the pixel layer of the SLM is designed as reflective pixels and that the transistors TFT associated with each pixel pair having a phase pixel Pp and an amplitude pixel Ap and at least a portion of the data line D of this pixel pair of the backplane in which the transistors TFT and the data line D are arranged are arranged behind or below the reflective pixels of the respective pixel pair, so that when the light passes through the respective pixels, the transistors and the data line assigned to or associated with each pixel pair do not reduce or make the slit of these pixels smaller. This means that since substantially half of the pixel layer of the SLM is designed as reflective pixels, here phase pixels Pp, light cannot pass through these reflective pixels, but is reflected by them. That is, light incident on the phase pixels Pp designed as reflective pixels is not transmitted by these pixels, but is reflected. Therefore, an area through which light cannot pass can be formed or provided on the side of the reflective pixels or phase pixels Pp which faces away from the incident light. Therefore, this back area of the respective reflective pixel, here the phase pixel Pp, can be used to accommodate components. Thus, for the reflective pixels, the backplane including the transistors and the data lines does not pass through the light at all. In other words, the back or lower area of each reflective pixel of each pixel pair through which light cannot pass is configured in this way by the transistors TFT assigned to each individual pixel pair and at least a portion of the associated data line D arranged therein. Each pixel of the pixel layer is assigned at least one transistor TFT, so that both the reflective pixels, here the phase pixels Pp, and the transmissive pixels, here the amplitude pixels Ap, are assigned at least one transistor TFT, as can be seen inThe at least two transistors TFT of each pixel pair can be arranged behind or below the reflective pixel, i.e. here the phase pixel Pp, such that the at least one transistor TFT assigned to the transmissive pixel, here the amplitude pixel Ap, does not limit the slit of the transmissive pixel. As already described with respect to Figure 2 and Figure 3 As disclosed, the data lines D of the backplane are usually arranged or arranged in horizontal and vertical direction, i.e. the data lines D in each case laterally horizontally and laterally vertically limit the respective pixels Pp and Ap. In this case, at least the vertical data lines Dv of the at least one transistor TFT assigned to and controlling the transmissive pixel of the pixel pair can be arranged behind or below the reflective pixel of the pixel pair, such that at least these vertical data lines Dv of the pixel pair do not limit the slit or opening of the transmissive pixel. The arrangement of the vertical data lines Dv assigned to the reflective pixel is likewise arranged behind or below the reflective pixel. Thus, at least a part of the data lines and transistors TFT for each pair of amplitude pixel Ap and phase pixel Pp are arranged below the reflective pixel. Thus, all transistors TFT and all vertically oriented or vertically arranged data lines Dv can thus be arranged in the area behind or below the reflective pixel. However, the data lines Dh arranged in horizontal direction are still covered by the black mask BM such that light not modulated in the prescribed manner cannot penetrate. However, compared to Figure 3 now, the area of the pixel layer blackened or covered by means of the black mask BM is significantly smaller, i.e. the transmissive area of the SLM through which light can penetrate is significantly larger. As a result, the available fill factor of the SLM increases significantly due to the larger extent of the pixel slit. The transistors TFT and data lines D are configured to conduct signals to the respective pixels.

[0117] Generally, Figures 4a to 4d The arrangement of the transistors TFT and data lines Dv and Dh of the SLM is shown in a top view, wherein the transistors TFT and vertical data lines Dv of each pair of amplitude pixel Ap and phase pixel Pp are arranged in each case in the phase pixel. Only the horizontal data lines Dh still pass through all pixels of the pixel layer of the SLM. It goes without saying that the shown arrangement can also be arranged in a rotated 90 degrees manner and that the amplitude pixels Ap and phase pixels Pp can overlap each other. Since in this exemplary embodiment the phase pixels Pp are designed as reflective pixels, i.e. from the backplane the reflective layer is arranged above the data lines Dv and Dh, these do not cause any disturbances in the phase pixels Pp. On the other hand, for the amplitude pixels Ap designed as transmissive pixels, this makes it possible to use a larger part of the pixel area or pixel slit for the passage of light.

[0118] According to Figure 4a The described and illustrated SLM can be further configured as shown in the subsequent Figures 4 to 8.

[0119] Figures 4b to 4dA spatial light modulating device (SLM) is shown that allows for simple production, Figure 4a The basic setup and mode of operation are shown, Figure 3 Different embodiments of the SLM are shown.

[0120] Figures 4a to 4d A side view of the SLM with a single addressable transmissive layer 10 (here in the form of a liquid crystal layer) between two substrates 11 and 12 is shown. By applying an electric field to the liquid crystal layer by means of an electrode arrangement, for example, the arrangement of the liquid crystals in the liquid crystal layer can be changed and in this way the modulation of light can be performed. In this case, the phase and the amplitude of the light incident on the SLM are modulated in adjacent pixels of the SLM. The SLM thus alternately has phase pixels Pp and amplitude pixels Ap adjacent to each other in the same plane. As already mentioned, a phase pixel Pp and an adjacent amplitude pixel Ap form a composite pixel pair. Here the phase pixels Pp are designed as reflective pixels and the amplitude pixels Ap are designed as transmissive pixels. The phase pixels thus have a reflective layer 13 in their rear or back region, as Figure 3 described, under which transistors and data lines can be hidden and arranged. However, it is not necessary to arrange the transistors and data lines downstream of the reflective layer of the reflective pixels of the SLM in the direction of light propagation. This means that a SLM according to Figure 2 does not need to be configured according to Figure 4a i.e. with the transistors and data lines arranged downstream of the reflective pixels in the direction of light propagation. The transistors and data lines of the SLM backplane can also be arranged in the SLM in the conventional manner known from the prior art, for example as Figure 4b described and shown.

[0121] An illumination device (not shown) configured as a backlight device emits collimated light to the SLM. The illumination device emits collimated light at a defined illumination angle (for example 10°), resulting in an oblique illumination of the SLM, as Figure 4aThe illumination angle is advantageous for several liquid crystal modes. The light incident on the SLM additionally has a defined polarization state which can be produced by a polarizer 14 arranged in the light incidence plane area of the SLM. The light in the direction of light propagation first passes through the phase pixel Pp and then through the amplitude pixel Ap in this order. In this case, the order of the modulation of the amplitude and the phase of the light can also be reversed in principle. However, with regard to the liquid crystal modulation, it is preferred that the light passes through the phase pixel Pp twice due to the reflection at the reflective layer 13, while, in contrast, it passes through the amplitude pixel Ap only once. Between the phase pixel Pp and the amplitude pixel Ap in the direction of light propagation, a reflection plane 15 is arranged at which the light modulated in phase by the phase pixel Pp is reflected and directed into the direction of the amplitude pixel Ap. In other words, the first transparent substrate 11 thus has on one side the addressable transmissive layer 10 with pixels and on the other, opposite side a plane which is configured as a reflection plane 15. The light now thus first impinges on the phase pixel Pp in a composite pixel pair consisting of a phase pixel Pp and an amplitude pixel Ap and is reflected at the reflective layer 13 behind the phase pixel Pp, which can be designed as a mirror element or a mirror layer, thus resulting in the implementation of a double pass arrangement within the phase pixel Pp. The thickness of the liquid crystal layer 10 required for the 2l phase shift which has to be set by the phase pixel Pp is thus reduced. The light reflected by the phase pixel Pp now propagates to the reflection plane 15 with the mirror system. The mirror system has mirror elements 16 which are designed to be reflective on the side or area facing the liquid crystal layer 10 with the pixels Pp and Ap and are arranged with respect to the reflective and transmissive pixels, i.e. with respect to the phase pixel Pp and the amplitude pixel Ap, such that each mirror element 16 covers a portion of the reflective pixel and a portion of the transmissive pixel. After the light is reflected at the mirror elements 16 of the mirror system, the light is diverted to the transmissive amplitude pixel Ap and is subjected to the corresponding amplitude modulation there.

[0122] In addition, a region (i.e. unstructured) retardation element 17, which can also be referred to as a retarder, is arranged in the reflection plane 15. This unstructured retardation element 17 serves to appropriately set the polarization of the light for the second pass of the light through the pixel of the pixel pair when the light passes through the two adjacent pixels forming the pixel pair (reflective pixel, here phase pixel Pp, transmissive pixel, here amplitude pixel Ap). The unstructured retardation element 17 can be designed as a quarter wave plate or 1 / 4 wave plate or an eighth wave plate or 1 / 8 wave plate.

[0123] By way of example, the SLM can be operated in the ECB mode (electrically controlled birefringence mode), as Figure 4dAs shown in the perspective view. For this liquid crystal mode, the phase pixel Pp used to modulate the phase of the light requires linearly polarized light with a polarization direction parallel to the orientation (alignment direction) of the liquid crystal molecules in the liquid crystal layer 10. In contrast, the amplitude pixel Ap used to modulate the amplitude of the light requires light that is also linearly polarized, but has a polarization direction rotated relative to the orientation of the liquid crystal molecules in the liquid crystal layer 10. The polarization direction of the light in the amplitude pixel Ap should preferably be set in a manner that rotates 45° relative to the orientation of the liquid crystal molecules.

[0124] First, let me clarify and explain this invention. Figure 4a and 4b The SLM shown operates in ECB mode. Of course, the SLM can also operate in different LCD modes, which will be discussed later. Figure 4a Discussion. Then, the incident on the basis Figure 4b and 4b The polarized light on the SLM passes through the retardation element 17 in the direction of light propagation before reaching the reflecting phase pixel Pp, which is the first pixel in the pixel pair. In the case of the ECB mode used here, the retardation element 17 is designed as a quarter-wave plate. However, since the phase pixel Pp requires linearly polarized light, and the retardation element 17 converts the incident linearly polarized light into circular light, a compensation retardation element 18 is provided to compensate for this light conversion. Like the unstructured retardation element 17, the compensation retardation element 18 is configured in a regional or unstructured manner. The compensation retardation element 18 can also be designed as a quarter-wave plate. The compensation retardation element 18 compensates for the polarization conversion of the unstructured retardation element 17, such that, overall, the combination of retardation elements 17 and 18 acts on the light incident on the phase pixel Pp, thereby producing linearly polarized light again. In other words, the compensation retardation element 18 interacts with the unstructured retardation element 17 so that the light incident on the pixel to which the first pixel in the pixel pair passes has or produces the desired polarization. Therefore, the compensation delay element 18 is arranged upstream of the reflection plane 15 of the SLM in the optical direction, such that light passes through the reflection plane upstream of the corresponding two pixels of the pixel pair in the SLM in the optical path. The compensation delay element 18 appropriately sets the polarization of the light for the first pixel in the pixel pair through which the light is to pass. However, the compensation delay element 18 is not absolutely necessary as long as light with a predetermined polarization is incident on the SLM, and the polarization is converted by the unstructured delay element 17 into the linear polarization of the light required by the phase pixel Pp.

[0125] Therefore linearly polarized light present downstream of the non-structured retardation element 17 and the compensating retardation element 18 in the direction of the light now impinges on the phase pixel Pp, is changed in phase accordingly, and is turned as reflected light into the direction of the reflection plane 15 and impinges again on the non-structured retardation element 17, as indicated by the arrow. The non-structured retardation element 17 acts as a half-wave plate in the double pass of the light, and therefore rotates the polarization of the light by twice the angle between the direction of the polarization of the impinging light and the optical axis of the non-structured retardation element 17, i.e. by 2 x 22.5°, i.e. by 45°. Therefore the polarization of the light is rotated by 45° with respect to the linear vertical polarization of the light impinging on the phase pixel. This polarization state is used to set the required impinging polarization at the amplitude pixel Ap. After the polarization state of the light has been changed, the latter now impinges on and passes through the amplitude pixel Ap. After passing through the amplitude pixel Ap, the light passes through the second substrate 12 according to Figure 4c and impinges on a polarizer 19 arranged in the light exit plane area of the SLM. The polarizer 19 allows the light from the amplitude pixel Ap with the prescribed polarization to pass, so that the modulated light leaves the SLM in the direction of the downstream components or elements in the light path. The polarizer 19 is here designed to have an optical axis which is rotated by -45° with respect to the required optical polarization rotation at the phase pixel Pp.

[0126] It is not absolutely necessary to arrange the non-structured compensating retardation element 18 and the polarizer 14 in the light entrance plane area of the SLM in the SLM. If light which has already been polarized in a prescribed manner impinges on the SLM, both elements, i.e. the compensating retardation element 18 and the polarizer 14, are not necessary, the polarization of the light being such that in combination with the non-structured retardation element 17 a polarization of the light is established which is required for the pixel which first passes through in a pixel pair consisting of a phase pixel Pp and an amplitude pixel Ap. In particular, for the ECB mode, this is the case if circularly polarized light impinges on the SLM. For example, if circularly polarized light impinges on the SLM, and if the non-structured retardation element 17 is designed as a quarter-wave plate which converts the circularly polarized light into linearly polarized light, this linearly polarized light impinges on the ECB phase pixel as required.

[0127] Furthermore, it is also possible to arrange such a configuration in which one of the two elements is necessary and the other is not necessary. For the ECB mode, the non-structured compensating retardation element 18 is necessary if the illumination device has already emitted light with a prescribed linear polarization, and the polarizer 14 arranged in the light entrance plane area of the SLM is not necessary. However, despite this, in order to further improve the degree of polarization of the light, it can be advantageous to arrange a polarizer in the SLM.

[0128] According to Figure 4aThe polarizer 14, which is located on the input side or is arranged in the light entrance plane area of the SLM, rotates the required polarization of the light at the phase pixel Pp by 45°. In this case, both the unstructured retardation element 17 and the compensating retardation element 18 can have the same optical axis of 22.5°, so that they together act as a half-wave plate (1 / 2 wave plate). In this case, the polarization direction of the light is subsequently rotated by 45° when the light emitted by the illumination device passes through both retardation elements 17 and 18, and the light reaches the phase pixel Pp with the required linear polarization of the phase pixel Pp. In this exemplary embodiment, linear vertically polarized light reaches the phase pixel Pp and, after reflection in the reflection plane 15, is rotated by 45° by the unstructured retardation element 17 and is incident on the adjacent amplitude pixel Ap.

[0129] Alternatively, the unstructured retardation element and the compensating retardation element can have optical axes that are rotated by 90° relative to one another, so that their effects cancel each other out, as shown in another case according to the ECB mode of Figure 4a and Figure 4b This SLM has the same components as the SLM according to Figure 4b and is in principle similar in terms of functionality. The unstructured retardation element 170 arranged here is again designed as a quarter-wave plate, and the compensating retardation element 180 is likewise designed as a quarter-wave plate. However, the orientation of the optical axes of the quarter-wave plates and the missing quarter of the polarizer is different from that in Figure 4a If the polarization direction of the input-side polarizer 140 of the SLM or of the polarizer arranged in the light entrance plane area of the SLM is 0 degrees (0°), so that this polarizer 140 transmits linear vertically polarized light, and the optical axis of the compensating retardation element 180 is -67.5° and the optical axis of the unstructured retardation element 170 is +22.5°, then the light is still linearly polarized at 0° after passing through the compensating retardation element 180 and the unstructured retardation element 170. In this way, as in Figure 4c , linear vertically polarized light is incident on the phase pixel Pp, which is first passed through in the pixel pair in the addressable transmission layer 100. After passing through the compensating retardation element 180 and the unstructured retardation element 170, the path of the light is from the phase pixel Pp via the reflection plane 150 (mirror element 160 with mirror system) to the amplitude pixel Ap, until the output-side polarizer 190 or the polarizer arranged in the light exit plane area of the SLM, which corresponds to the previously described configuration of the SLM according to Figure 4d and 4b . A repeated description of the light path through the components of the SLM shown in Figure 4a will therefore be omitted.

[0130] For SLMs based on the ECB mode according to Figure 4dOther liquid crystal modes based on in-plane modulation, such as IPS mode (in-plane switching), or other modes based on in-plane rotation of the liquid crystal in an external electric field, require linearly polarized light for amplitude pixels and circularly polarized light for phase pixels. Here, the basic settings of an SLM based on in-plane modulation correspond in principle to... Figure 4a The SLM settings.

[0131] After light leaves the phase pixel and before it incident on the amplitude pixel in the pixel pair, the polarization of the light must therefore be changed from circularly polarized to linearly polarized. This can be determined according to... Figure 4a This can be achieved, for example, by using an unstructured delay element 1700 designed as an eighth-wave plate. In this case, light passes through the unstructured delay element 1700 twice; this element has an optical axis of 45°, so its total effect is that of a quarter-wave plate. In this case, an eighth-wave plate can be set as a compensating delay element 1800, whose optical axis is also 45° and is unstructured. Since this SLM setup corresponds in principle to... Figure 4a The SLM is configured such that light incident on the SLM first deflects to the phase pixel Pp, then reflects at the reflection plane 1500 before deflecting to the amplitude pixel. The other components of the SLM correspond to... Figures 4a to 4d The components of the SLM are as follows. This means that an addressable transmissive layer 1000 (preferably a liquid crystal layer) is embedded between two substrates, the layer having reflective pixels and transmissive pixels. Furthermore, a reflective plane 1500 with a mirror system, including mirror elements 1600 and an unstructured retardation element 1700, is provided in the light direction between the reflective phase pixel Pp and the transmissive amplitude pixel. Additionally, the SLM has a polarizer 1400 disposed in the light incident plane region of the SLM, the polarizer having a 0° optical axis, thereby transmitting linearly vertically polarized light to the compensation retardation element 1800. This light, rotated 45° by the compensation retardation element 1800, is incident on the unstructured retardation element 1700, and is rotated again by 45° via the unstructured retardation element 1700, thereby generating circular polarization. Subsequently, the circularly polarized light is incident on the phase pixel Pp, reflected at its rear end by the reflective layer 1300, and the reflected phase-modulated light is directed towards the reflective plane 1500. Viewed from the direction of light, the light passes through the unstructured delay element 1700, is incident on the mirror element 1600, and then passes through the unstructured delay element 1700 again, such that after passing through the unstructured delay element 1700, the light has now changed from circular polarization to linear polarization. In this case, linearly vertically polarized light is now incident on the amplitude pixel Ap. After the amplitude of the light is modulated, the light passes through a polarizer 1900 disposed in the light exit plane region of the SLM, the optical axis of which is 90°, causing the horizontally linearly polarized light to leave the polarizer 1900, thereby leaving the SLM.

[0132] In this way, according to the embodiments of the application Figure 3 , 4b , 4c and 4d, the structure of the unstructured retardation element 17, 170, 1700 can be dispensed with. As a result, the production of the SLM itself can be significantly simplified and facilitated, since an exact alignment of the area or unstructured retardation element 17, 170, 1700 with the mirror elements 16, 160, 1600 of the mirror system can be circumvented or avoided.

[0133] The SLM can similarly have other elements or components, such as an apodized profile or other polarization filter elements. However, since these are not essential to the application, they will not be described in detail.

[0134] As described in Figures 4a to 4d , these extensions and improvements of the application according to Figure 2 have been described in connection with an SLM with transistors and data lines arranged below the reflective pixels. However, it is also possible that the embodiments according to Figures 4a to 4d themselves can also be considered an invention, thus an extension and improvement of a conventional SLM according to the prior art, in which the transistors and data lines are not arranged directly below the reflective pixels, thus a conventional black mask is used. As described above, such an SLM already has reflective pixels, wherein the transmissive and reflective pixels are located or arranged in one and the same plane. Thus, this means that a conventional SLM according to the prior art as shown in Figure 5 can be set up, which is combined with the improvements / extensions and features described in the embodiments according to Figure 3 .

[0135] Thus, such an SLM has the following features:

[0136] A spatial light modulation device comprising:

[0137] • pixels, substantially half of the pixels are designed as reflective pixels, the other half of the pixels are designed as transmissive pixels, the reflective pixels and the transmissive pixels are arranged alternately on one and the same substrate plane.

[0138] • an unstructured retardation element arranged in a reflective plane, the reflective plane is arranged between the reflective pixels and the transmissive pixels in the direction of light propagation.

[0139] • at least one transparent substrate and an addressable transmissive layer, the addressable transmissive layer is preferably designed as a liquid crystal layer containing liquid crystal molecules and forms the pixels as modulation elements for modulating the incident light.

[0140] • the reflective pixels are designed as phase pixels, the transmissive pixels are designed as amplitude pixels.

[0141] • The reflective pixel has a reflective layer, preferably a mirror element, which is arranged at the back end of the reflective pixel in the direction of light propagation.

[0142] • The at least one transparent substrate has on one side an addressable transmissive layer comprising pixels and on the other opposite side a plane designed as a reflective plane.

[0143] • The reflective plane has a mirror system at which light is reflected between the reflective pixel and the transmissive pixel.

[0144] • The mirror system has mirror elements designed to be reflective on the side facing the addressable transmissive layer comprising pixels.

[0145] • The mirror elements of the mirror system are arranged with respect to the reflective pixel and the transmissive pixel such that each mirror element covers a portion of the reflective pixel and a portion of the transmissive pixel.

[0146] • The addressable transmissive layer is connected to the reflective plane such that the incident light passes the reflective pixel and the transmissive pixel of the addressable transmissive layer, the light being reflected between the two by the reflective plane.

[0147] • An unstructured retardation element is arranged in the reflective plane configured to set the polarization of the incident light for the second passing pixel of a pixel pair when the light passes the adjacent pixel pair consisting of the reflective pixel and the transmissive pixel, the reflective pixel and the transmissive pixel being designed as phase pixel and amplitude pixel, together forming a composite pixel pair.

[0148] • The unstructured retardation element is designed as a quarter wave plate or an eighth wave plate.

[0149] • A compensating retardation element, the compensating retardation element being unstructured, designed as a quarter wave plate or an eighth wave plate, the compensating retardation element interacting with the unstructured retardation element such that the light incident on the first passing pixel of the pixel pair has the required polarization.

[0150] • The optical axis of the unstructured retardation element and the compensating retardation element are the same or they are rotated by 90° with respect to each other.

[0151] • Two polarizers, one polarizer arranged in the light entrance plane area of the light modulation device and the other polarizer arranged in the light exit plane area of the light modulation device.

[0152] • A backplane comprising transistors and data lines for conducting signals to the pixels, each pixel being assigned at least one transistor and at least two data lines, the transistors and data lines of each adjacent pixel pair consisting of a reflective pixel and a transmissive pixel being arranged below the reflective pixel in the direction of light propagation.

[0153] • The backplane has black masks assigned to the transistors and data lines, the black masks being configured such that the black masks do not cover the edge regions of the pixel slits over their entire extension.

[0154] • The pixels are designed in a rectangular manner, the slits of the pixels being first on two opposite sides and being unrestricted on the other two opposite sides.

[0155] Figure 5 An embodiment of an SLM according to Figure 5 is shown which helps to increase the light intensity. Thus, here also the transistors and data lines are arranged under the reflective pixels in order to increase the fill factor of the SLM. It goes without saying that for an SLM according to Figure 4a the transistors and data lines of the backplane of the SLM are not absolutely necessary arranged behind the reflective pixels. A conventional arrangement of the transistors and data lines is equally feasible. Thus, Figure 3 a side view of a configuration of a spatial light modulating device for improving the light efficiency is shown. The basic setup of the SLM shown here corresponds in principle to the setup of an SLM according to Figures 4a to 4d .

[0156] That is to say, here the SLM has a single addressable transmissive layer 30 between the two substrates 31 and 32, here also in the form of a liquid crystal layer. The phase pixels Pp and the amplitude pixels Ap are again arranged as composite pixel pairs alternating with each other in one and the same plane of the SLM. Here, the phase pixels Pp are also designed as reflective pixels, the amplitude pixels Ap as transmissive pixels. In order to achieve the reflectivity of the phase pixels Pp, the phase pixels Pp have a reflective layer 33 in their rear end or back region, as Figure 5 is stated, under which reflective layer the transistors and data lines can but are not necessarily hidden and arranged.

[0157] An illumination device (not shown) emits collimated light onto the SLM, the illumination device being configured here as a backlight device, but can also be configured as a front light illumination device. The illumination device emits collimated light at a defined illumination angle (for example 10°), thereby producing an oblique illumination of the SLM. Furthermore, the light incident on the SLM has a defined polarization state, which is produced or further improved by a polarizer 34 arranged in the light incidence plane region of the SLM. It can be seen that the light in the direction of light propagation first passes through the phase pixels Pp and then through the amplitude pixels Ap, here also in the reverse order. Between the phase pixels Pp and the amplitude pixels Ap in the direction of light propagation a reflection plane 35 is arranged, at which the light modulated in phase by the phase pixels Pp is reflected and reflected in the direction of the amplitude pixels Ap. As Figure 5As shown, the light first impinges on the phase pixel Pp of the pixel pair, is reflected at the back end of the phase pixel Pp at a reflection layer 33, which can be designed as a mirror element or mirror layer, and passes again through the phase pixel Pp. The light reflected by the phase pixel Pp now propagates to a reflection plane 35 with a mirror system and an unstructured retardation element 38. The mirror elements 36 of the mirror system are designed to be reflective on the side or area facing the liquid crystal layer 30 with the pixels Pp and Ap and are arranged with respect to the reflective and transmissive pixels, i.e. with respect to the phase pixels Pp and the amplitude pixels Ap, such that each mirror element 36 covers a portion of the reflective pixels and a portion of the transmissive pixels. After the light has been reflected at the mirror elements 36 of the mirror system and has passed again through the unstructured retardation element 38, the light with the changed polarization state is directed to the transmissive amplitude pixels Ap and is there subjected to the respective amplitude modulation, as shown by the dashed beam path of the light in the figure. If the polarization state of the light is correct, the light emitted from the transmissive amplitude pixels Ap impinges on a polarizer 37 arranged in the light exit plane area of the SLM and is transmitted by said polarizer.

[0158] In order to modulate the light by two pixel pairs of adjacently arranged SLMs, the light successively passes through these pixels in the light path, it is necessary to block a certain proportion of the incident light in the light entry side area or input side of the SLM, so that the light is only directed in the direction of the pixel, preferably the phase pixel, which is to be passed first in the pixel pair, and only reaches the second pixel, preferably the amplitude pixel, in the pixel pair after passing the first pixel, e.g. the phase pixel. However, in arrangements according to the prior art, e.g. according to US 2016 / 0327906 Al, this light would be lost, which can have a disadvantageous effect on the light efficiency of the SLM.

[0159] In order to increase or improve the light efficiency of the SLM, in Figure 5 the mirror elements 36 for reflecting the light in the reflection plane 35 between the amplitude pixels Ap and the phase pixels Pp are designed such that the mirror elements 36 not only act as mirror elements or have a reflective effect on the inner side, i.e. towards the modulating liquid crystal layer 30, but they also reflect light on the input side or as seen from the direction of the illumination device. In other words, the mirror elements 36 are designed to be reflective on both sides, the side facing the liquid crystal layer 30 with the pixels Pp and Ap and the side facing away from the liquid crystal layer 30. In the light entry plane area of the SLM, the polarizer 34 is designed as a reflective polarizer, i.e. as a polarizer which is designed to be transmissive for one specified polarization and reflective for the other specified polarization. The reflective polarizer 34 can for example be designed as a wire grid polarizer (WGP). Furthermore, according to Figures 4a to 4dIn this exemplary embodiment, a compensation delay element 39, which may also be referred to as an optical recirculation delay element or an optical recirculation element, is also provided. The compensation delay element 39 or optical recirculation delay element 39 or optical recirculation element 39 is configured in an unstructured manner and is arranged downstream of the reflective polarizer 34 disposed in the light incident plane region of the SLM in the optical direction. In this case, to improve the optical efficiency of the SLM, the optical axis of the compensation delay element 39 is aligned with the optical axis of the reflective polarizer 34, such that light incident on the input side of the mirror element 36 is reflected by the mirror element and oriented or returned to the direction of the reflective polarizer 34, rotating relative to its polarization. Therefore, at least a portion of the light is reflected by the reflective polarizer 34 and again toward the first pixel in the pixel pair (here, in…). Figure 6 The direction of the phase pixel Pp is oriented for modulation, as shown by the solid black arrow. Preferably, for further modulation purposes, the reflective polarizer 34 directs the entire light in the direction of the first pixel in the pixel pair. Therefore, the compensation delay element 39 performs two tasks here: compensating for the effect of the unstructured delay element 38 (as shown by the solid black arrow). Figure 5 (Publicly available), and its effect as a light recycling element.

[0160] By setting the distance d2 between the reflective polarizer 34 and the mirror element 36 to a value that is almost the same as the thickness d1 of the substrate (here, the first substrate 31) between the mirror element 36 and the addressable transmissive layer 30 (in the form of a liquid crystal layer), the result is that after reflection at the reflective polarizer 34, the light reaches the opening or slit of the first pixel in the pixel pair and no longer incident on the mirror element 36.

[0161] Figure 6 It shows according to Figure 5 The SLM is used for an embodiment of the in-plane mode of the SLM. However, for clarity, Figure 3Only the area of the SLM after the reflection-type polarizer is set in the light entry plane area and after the light has passed the unstructured retardation element in the reflection plane is shown. The compensation retardation element 390, which is set in the SLM, in this case unstructured and designed as a quarter wave plate with its optical axis arranged at 45°, also serves to circularly polarize the reflected light from the reflection-type polarizer 340, which has its optical axis at 0°, so that the circularly polarized light reaches the phase pixel in the complex pixel pair consisting of a reflection pixel and a transmission pixel, preferably a reflection phase pixel and a transmission amplitude pixel, and can be passed through and modulated by said phase pixel. This means that after the linear vertically polarized light has entered the SLM through the reflection-type polarizer 340, which transmits linear vertically polarized light and reflects linear horizontally polarized light, it hits the compensation retardation element 390, which is designed as a quarter wave plate. The light then hits the mirror element 360 of the mirror system set in the reflection plane 350 and is reflected from said mirror element back to the reflection-type polarizer 340 through the compensation retardation element 390. After two passes through the compensation retardation element 390, the light is circularly polarized. After the light has been reflected at the mirror element 360 of the mirror system in the reflection plane 350, approximately 50% of the light is then reflected at the reflection-type polarizer 340, which then initially linearly polarizes the light again, i.e. linearly horizontally polarizes it, while the other 50% of the light is transmitted by the reflection-type polarizer 340 and optionally coupled back into the illumination device. After the reflected light has passed through the compensation retardation element 390 and the slit in the reflection plane 350 again, the light hits the unstructured retardation element 380, which has its optical axis also at 45° and is designed as a quarter wave plate. The compensation retardation element 390 and the unstructured retardation element 380 together act as a quarter wave plate and convert the horizontally linearly polarized light into right-handed circularly polarized light, so that the light can reach the phase pixel (not shown) in the direction of the arrow shown after it as circularly polarized light, if necessary. The further light propagation corresponds to the light path described. Figure 5

[0162] However, the arrangement for increasing the light efficiency is also very suitable for SLMs whose amplitude pixels and phase pixels modulate the light independently of the polarization. This is the case, for example, with SLMs based on electrical weaving or SLMs based on multiple quantum wells. The compensation retardation element 390 can then be designed as a quarter wave plate with its optical axis at 45° with respect to the polarizer 340. The polarization of the light reflected by the mirror element 360 and passed back to the reflection-type polarizer 340 through the compensation retardation element 390 is rotated by 90° and is completely reflected at the polarizer 340. In this case, the unstructured retardation element 380 is not required.

[0163] The arrangement has been combined Figure 5 and 4a ​The description of the exemplary embodiments of the application disclosed in Figure 6 and 6 is also applicable to the exemplary embodiments of the application described in Figure 2 and Figure 5 . The combination of such elements is expedient and advantageous. However, it is also possible for the embodiments according to Figure 2 and Figure 5 to be considered as an invention on their own and thus as an extension and improvement of the conventional construction of SLMs according to the prior art, in which the transistors and data lines are not arranged directly below the reflective pixels and thus a conventional black mask is used. As already mentioned above, such SLMs already have reflective pixels, wherein the transmissive pixels and the reflective pixels are located or arranged in one and the same plane. This means, therefore, that a conventional SLM arranged according to the prior art, for example as shown in Figure 8 and Figure 8 and 6 in combination with the improvements / extensions and features described in the embodiments according to Figure 8 and 6 .

[0164] Such a SLM thus has the following features:

[0165] A spatial light modulating device comprising:

[0166] • pixels, substantially half of the pixels being designed as reflective pixels and the other half of the pixels being designed as transmissive pixels, the reflective pixels and the transmissive pixels being arranged alternately in the same substrate plane.

[0167] • a compensating retardation element or a light recycling retardation element or a light recycling element, the compensating retardation element being a non-structured compensating retardation element and being designed as a quarter wave plate or an eighth wave plate.

[0168] • a polarizer arranged in the light entry plane area of the light modulating device, the polarizer being designed as a reflective polarizer, preferably as a wire grid polarizer.

[0169] • a further polarizer arranged in the light exit plane area of the light modulating device.

[0170] • at least one transparent substrate and an addressable transmissive layer, the addressable transmissive layer preferably being designed as a liquid crystal layer comprising liquid crystal molecules and forming the pixels as modulation elements for modulating the incident light.

[0171] • the reflective pixels being designed as phase pixels and the transmissive pixels being designed as amplitude pixels.

[0172] • the reflective pixels having a reflective layer, preferably a mirror element, the reflective layer being arranged at the back end of the reflective pixels in the direction of light propagation.

[0173] • the at least one transparent substrate having on one side the addressable transmissive layer comprising the pixels and on the other, opposite side a plane designed as a reflective plane.

[0174] • the reflective plane has a mirror system at which light is reflected between the reflective pixels and the transmissive pixels.

[0175] • the mirror system has mirror elements designed to be reflective on both sides towards and away from the addressable transmissive layer with pixels.

[0176] • the mirror elements of the mirror system are arranged relative to the reflective pixels and the transmissive pixels such that each mirror element covers a portion of the reflective pixels and a portion of the transmissive pixels.

[0177] • the addressable transmissive layer is coupled to the reflective plane such that incident light passes through both the reflective pixels and the transmissive pixels of the addressable transmissive layer, the light being reflected between the two by the reflective plane.

[0178] • the distance between the polarizer arranged in the light incidence plane area of the light modulating device and the mirror elements of the mirror system in the reflective plane is set to the same value as the thickness of at least one substrate between the mirror elements of the mirror system and the addressable transmissive layer with pixels.

[0179] • a backplane comprising transistors and data lines for conducting signals to the pixels, each pixel being assigned at least one transistor and at least two data lines, the transistors and data lines of each adjacent pair of pixels consisting of a reflective pixel and a transmissive pixel being arranged below the reflective pixel in the direction of light propagation.

[0180] • the backplane has a black mask assigned to the transistors and data lines, the black mask being configured such that the black mask does not cover edge regions of the pixel gap over its entire extension.

[0181] • the pixels are designed in a rectangular manner, the gap of the pixels being limited on two opposite sides and not limited on the other two opposite sides.

[0182] • an unstructured retardation element arranged in the reflective plane arranged between the reflective pixels and the transmissive pixels in the direction of light propagation.

[0183] • the unstructured retardation element is arranged in the reflective plane configured for setting a polarization of incident light for a second passing pixel of an adjacent pair of pixels consisting of a reflective pixel and a transmissive pixel when light passes through the pair of pixels, the reflective pixel and the transmissive pixel being designed as phase pixels and amplitude pixels, together forming a complex pixel pair.

[0184] • the unstructured retardation element is designed as a quarter wave plate or an eighth wave plate.

[0185] Another embodiment of an SLM is shown in Fig. 7. In this exemplary embodiment, an unstructured arrangement of amplitude pixels and phase pixels according to the prior art, i.e. an unstructured arrangement of the orientation of the liquid crystal molecules, is used in the SLM. Fig. 7 thus shows a pixel arrangement of an SLM, in which an unstructured arrangement of the liquid crystal molecules LCM is shown in a top view. This unstructured arrangement of the liquid crystal molecules LCM is feasible both in the ECB mode and in the in-plane mode of the SLM. As can be seen, in this pixel arrangement, the phase pixels Pp and the amplitude pixels Ap are also arranged adjacent in the same plane. The liquid crystal molecules LCM of the phase pixels Pp are arranged in the same or similar manner as the liquid crystal molecules LCM of the amplitude pixels Ap. Here, the molecular longitudinal axes of the liquid crystal molecules LCM, i.e. the longitudinal axes of the phase pixels Pp and the molecular longitudinal axes of the amplitude pixels Ap, all point in the same direction.

[0186] However, in order to simplify the setup of the SLM, according to Figures 4a to 6 Exemplary embodiments of an SLM are provided, in which a structured arrangement of the liquid crystal molecules LCM of the phase pixels Pp and the amplitude pixels Ap is provided. Figures 4a to 6 This is shown in a top view. In this case, the liquid crystal molecules LCM2 in the amplitude pixels Ap are arranged in a manner rotated by 45° compared to the liquid crystal molecules LCM1 in the phase pixels Pp by means of optical alignment. This has the advantage in the case of the ECB mode and similar liquid crystal modes that the optical polarization between the phase pixels Pp and the amplitude pixels Ap either does not need to be rotated at all or can be rotated by 90°.

[0187] In the first case without a setup of an optical polarization rotation, it is possible to avoid a setup of an unstructured or even structured retardation element in the beam path between the phase pixels and the amplitude pixels, as Figure 8 is shown. In the second case described above, the polarization of the light is rotated by 90°, it is possible to set up an unstructured retardation element, as Figure 8 is shown, which is preferably designed as a quarter-wave plate, the optical axis of which is set to approximately 45°.

[0188] It is possible to set up an SLM according to Figure 9This structured arrangement of the liquid crystal molecules LCM in the pixels of the SLM in order to reduce the crosstalk between adjacent pixels of the addressable transmissive layer of the SLM. This is because the light is diffracted at the slits of the SLM, thus creating a diffraction effect, which disadvantageously leads to the diffracted light not only being incident on the first pixel (preferably phase pixel) of the composite pixel pair in the same plane of the SLM to be passed through, but also on the second pixel (preferably amplitude pixel) arranged next to the first pixel. As a result, the light incident on the second pixel of the pixel pair only has a modulation of this type of pixel before it exits from the SLM, that is to say, for example, the light is only incident on the amplitude pixel, thus only modulating its amplitude, and leaves the SLM without a phase modulation. In order to counter this, a polarizer arranged in the light exit plane area of the SLM can be provided. However, this polarizer needs to be specifically set up such that the light modulated only by the second pixel is not actually transmitted or not allowed to pass through the SLM.

[0189] If an ECB mode is used in the SLM, for example, in which the polarization of the light between the phase pixel and the amplitude pixel is rotated by 45°, and a polarizer needs to be arranged in the light exit plane area of the SLM, which is parallel or perpendicular to the polarization of the light incident on the SLM, then the polarizer on the output side or the polarizer arranged in the light exit plane area of the SLM also has to be rotated by 45° with respect to the polarization incident on the first pixel (for example phase pixel) of the pixel pair. Then, if due to the diffraction, light is directly incident on the adjacent second pixel (for example amplitude pixel) of the pixel pair, due to its incorrect polarization, its amplitude is not even modulated in the first place, but the light passes through the amplitude pixel as the second pixel and is incident on the output side polarizer arranged in the light exit plane area of the SLM. The polarizer arranged in the light exit plane area of the SLM absorbs and filters about 50% of this light, but the other 50% of the light can pass through the polarizer. Thus, the output side polarizer only partially filters but does not completely filter the undesired light incident on the second pixel of the pixel pair. In contrast, the filtering effect of the 50% of the diffracted light is the same for all pixels of the SLM, independent of the set amplitude and phase values.

[0190] However, if the structured alignment of the liquid crystals in the amplitude pixels and phase pixels of the SLM is used as disclosed and described above, in which the orientation of the liquid crystal molecules in the amplitude pixels is rotated by 45° with respect to the orientation of the liquid crystal molecules in the phase pixels, as Figure 9If the polarization of the light is not rotated between the phase pixel and the amplitude pixel, then it can not be necessary to rotate the polarization of the light. This means that no structured or unstructured retardation elements need to be provided in the SLM for rotating the polarization of the light. The polarizer provided in the light exit plane area of the SLM is provided in such a way that it rotates the polarization of the light by 90° with respect to the polarization of the light incident on the phase pixel. However, in this case the light directly incident on the second pixel of the composite pixel pair (e.g. the amplitude pixel adjacent to the phase pixel) due to diffraction at the SLM opening will also be modulated in amplitude, since the orientation of the liquid crystal molecules in the second pixel is rotated by 45° with respect to the orientation of the liquid crystal molecules in the first pixel of the pixel pair through which the light passes. However, this light is not subsequently phase modulated. Thus, the proportion of light transmitted by the polarizer provided in the light exit plane area of the SLM is proportional to the amplitude of the pixel.

[0191] This configuration of the SLM described is particularly advantageous, since in this case the crosstalk between the pixels of the addressable transmission layer of the SLM due to diffraction of the light does not have a disturbing effect on the contrast of the SLM. The pixels designed as composite pixel pairs and having an amplitude value of zero (0) also remain at amplitude 0, despite the diffraction or non-transmission of light, since the diffracted light is completely filtered for these pixels.

[0192] Figure 4a An embodiment of the SLM is shown in which the desired light path, i.e. the reflection of the incident light at the first pixel of the composite pixel pair and at the mirror element of the mirror system in the reflection plane, is completely through the polarizer provided in the light exit plane area of the SLM, while the light which due to the diffraction of the slit at the input of the SLM (i.e. in the plane of the mirror element) does not fall on the first pixel of the pixel pair and which directly passes through the second pixel of the pixel pair is then filtered according to the amplitude value of the light at the output side or the polarizer provided in the light exit plane area of the SLM.

[0193] As Figure 8As shown, the SLM has a first substrate 61 and a second substrate 62, between which an addressable transmissive layer 63, preferably a liquid crystal layer, is embedded. Here, the addressable transmissive layer 63 also has reflective pixels and transmissive pixels, the reflective pixels preferably being phase pixels Pp and the transmissive pixels preferably being amplitude pixels Ap. The reflective pixels or phase pixels Pp have a reflective layer 64 at their rear end, at which the incident light is reflected. The reflective layer 64 can be designed as a mirror element. The transistors and data lines of the backplane can be arranged behind or below the reflective layer 64 in order to increase the aperture of the pixels and the fill factor of the SLM. However, this is not absolutely necessary, the transistors and data lines of the backplane can also be arranged and provided in a conventional manner with respect to the addressable transmissive layer 63. Between the phase pixels Pp and the amplitude pixels Ap, in the direction of the light, a reflective plane 65 is provided, at which the phase pixels Pp and the amplitude pixels Ap are also arranged alternately next to each other in such a way that they form a composite pixel pair in one and the same plane. A mirror system comprising a mirror element 66 is provided in the reflective plane, at which the light reflected by the phase pixels Pp is incident, reflected and directed in the direction of the transmissive amplitude pixels Ap. This process corresponds in principle to the optical path according to Figure 9 .

[0194] Then, in order to reduce or avoid crosstalk between adjacent pixels, for example between a phase pixel Pp and an adjacent amplitude pixel Ap, as shown in Figure 9 and Figure 4a , the liquid crystal molecules LCM2 of the amplitude pixels Ap are oriented in such a way that they are rotated by 45° with respect to the liquid crystal molecules LCM1 of the phase pixels Pp. This is evident from the different orientations or representations of the liquid crystal molecules LCM1 and LCM2 in Figure 9 . As shown by the black solid arrows, the light or light of further increased polarization, which is polarized by a polarizer 68 provided in the light entrance plane region of the SLM, passes through the aperture 67 present in the reflective plane 63, is incident on the phase pixel Pp to modulate the phase, is reflected at the reflective layer 64 and is further directed to the reflective plane 65, where it is likewise reflected at the mirror element 66 and then turned in the direction of the amplitude pixel Ap. There, as described with respect to Figure 3 , the light is amplitude-modulated and passes through an output-side or polarizer 69 provided in the light exit plane region of the SLM and then exits the SLM. However, at the aperture 67, the incident light is also diffracted, so that a portion of this diffracted light portion does not incident on the phase pixel Pp, but on the pixel adjacent to the phase pixel Pp, namely the amplitude pixel Ap, as shown in Figure 8The light incident on the adjacent pixel, here the amplitude pixel Ap, is amplitude-modulated but not phase-modulated and, after passing through the second substrate 62, is incident on a polarizer 69 arranged in the light exit plane area of the SLM. Depending on the amplitude value, the light is then filtered or completely absorbed by the polarizer 69, so that the light does not leave or exit the SLM.

[0195] In addition, a color filter of the primary colors RGB (red, green, blue) can be used to reduce crosstalk between adjacent pixels in the SLM due to diffraction. In this case, the color filter is assigned to the pixels of the SLM, in which case, for example, each pixel is subdivided into three subpixels and a red, green and blue color filter is assigned to the three subpixels. This is repeated alternately in the pixel arrangement, since in each case an amplitude pixel and a phase pixel have the same color filter, but adjacent pairs of amplitude and phase pixels have different color filters. If the SLM is subsequently illuminated with a specific wavelength, the light of the adjacent pixels having a different assigned color filter not corresponding to the current wavelength will be blocked by their color filter. This, for example, prevents a situation in which light that would have originally been incident first on a phase pixel and then on an amplitude pixel in the same pixel pair passes through the adjacent amplitude pixel due to diffraction.

[0196] The application has been described in connection with Figure 3 and / or 4a to 4d (i.e. SLMs in which transistors and data lines are arranged below the reflective pixels). Figure 8 and 9 The exemplary embodiments of the application disclosed in Figure 9 are particularly expedient and advantageous in combination, in particular in combination with the features according to Figure 2 and Figures 3 to 9 It is also possible, however, for the embodiments according to Figure 2 and Figures 3 to 9 to be considered as an invention in their own right, thus being an extension and improvement of the conventional construction of SLMs according to the prior art, in which transistors and data lines are not arranged directly below the reflective pixels, thus a conventional black mask being used. As mentioned above, such SLMs already have reflective pixels, in which the transmissive pixels and the reflective pixels are located or arranged in the same plane. This means, therefore, that a conventional SLM arranged according to the prior art, as described and illustrated in Figure 10 , can be provided in combination with the improvements / extensions and features described in the embodiments according to Figure 10 and 9 .

[0197] Such a SLM thus has the following features:

[0198] A spatial light modulation device, comprising:

[0199] • The pixels, substantially half of the pixels are designed as reflective pixels, the other half of the pixels are designed as transmissive pixels, the reflective pixels and the transmissive pixels are arranged alternately on the same substrate plane.

[0200] • The orientation of the liquid crystal molecules of the pixels can be arranged such that the orientation of the liquid crystal molecules of the transmissive pixels is rotated by 45° with respect to the orientation of the liquid crystal molecules of the reflective pixels.

[0201] • A polarizer arranged in the light exit plane area of the light modulation device, which polarizes the light incident on the first pixel of the pixel pair by 90° with respect to the polarization of the light incident on the first pixel of the pixel pair by the reflective pixels and the transmissive pixels.

[0202] • In each case, the undesired diffracted light incident on the pixels adjacent to the pixels of the light to be modulated can be filtered by the polarizer arranged in the light exit plane area of the light modulation device.

[0203] • In each case, the undesired diffracted light incident on the pixels adjacent to the pixels of the light to be modulated can be filtered by the polarizer arranged in the light exit plane area of the light modulation device, depending on the amplitude value of the adjacent pixels.

[0204] • A further polarizer, which is arranged in the light entrance plane area of the light modulation device.

[0205] • At least one transparent substrate and an addressable transmissive layer, the addressable transmissive layer is preferably designed as a liquid crystal layer containing liquid crystal molecules and forms the pixels as modulation elements for modulating the incident light.

[0206] • The reflective pixels are designed as phase pixels, the transmissive pixels are designed as amplitude pixels.

[0207] • The reflective pixels have a reflective layer, preferably a mirror element, which is arranged at the rear end of the reflective pixels in the direction of light propagation.

[0208] • The at least one transparent substrate has on one side an addressable transmissive layer containing the pixels and on the other opposite side a plane designed as a reflective plane.

[0209] • The reflective plane has a mirror system, at which the light is reflected between the reflective pixels and the transmissive pixels.

[0210] • The mirror system has mirror elements, which are designed to be reflective on the side facing the addressable transmissive layer with the pixels.

[0211] • The mirror elements of the mirror system are arranged with respect to the reflective pixels and the transmissive pixels such that each mirror element covers a portion of the reflective pixels and a portion of the transmissive pixels.

[0212] • An addressable transmission layer is coupled to a reflective plane, so that incident light passes through the reflective and transmission pixels of the addressable transmission layer, and the light is reflected between the two through the reflective plane.

[0213] • The backplane includes transistors and data lines for transmitting signals to pixels, with each pixel allocated at least one transistor and at least two data lines, and the transistors and data lines of each adjacent pixel pair consisting of a reflective pixel and a transmissive pixel are arranged below the reflective pixel (in the direction of light propagation).

[0214] • The backplane has black masks assigned to transistors and data lines, and the black masks are configured so that they do not cover the edge areas of the pixel gaps throughout the entire extension.

[0215] • The pixels are designed in a rectangular shape, with the gaps between pixels restricted on two opposite sides and unrestricted on the other two opposite sides.

[0216] Figure 10 The SLM disclosed and illustrated herein can be used in display devices for representing two-dimensional and / or three-dimensional objects or scenes. Such display devices include... ​ As shown.

[0217] ​ A preferred configuration of the display device according to the invention is described. For example, the display device can be used with the liquid crystal in ECB mode, or it can be used with the SLM operating in in-plane mode. For the addressable transparent layer 80 comprising complex-valued pixels (e.g., pixel pairs consisting of phase pixels Pp and amplitude pixels Ap), the liquid crystal layer in the SLM is preferably used. In addition to the SLM, the display device has an illumination device 81, here in the form of a backlight device, which generates light by means of at least one light source and emits it onto the SLM. The SLM requires polarized light, the polarization state of which is either already set in the illumination device 81 or can be set by a polarizer 82 (e.g., a polarizer 82 disposed in the light incident plane region of the SLM). ​ As shown, linearly polarized light enters the SLM, which is formed in a sandwich configuration by an addressable transmission layer 80 and a reflective plane 83. The reflective plane 83 is disposed between a polarizer 82 and the addressable transmission layer 80, and together with the polarizer 82, forms the light incident plane of the SLM. Corresponding transmission substrates 85 and 86 are disposed as spacers between the addressable transmission layer 80 and the reflective plane 83, and between the addressable transmission layer 80 and the polarizer 84 disposed in the light emitting region of the SLM. When ECB mode is used in the addressable transmission layer 80, the phase pixel Pp, which is the first pixel in the composite pixel pair incident upon light entering the SLM, changes the phase of the light without changing its polarization state. This can be attributed to the orientation of the liquid crystal in the addressable transmission layer 80.

[0218] Light incident on a phase pixel Pp is reflected by the reflective layer 87 located at the back end of the phase pixel Pp, passes again through the phase pixel and is directed back in the direction of the illumination device 81. In this way, the light is incident on a reflection plane 83 having a mirror system comprising mirror elements 88 and an unstructured retardation element 89 which introduces a defined retardation. The light is reflected by the mirror elements 88 and converted by the unstructured retardation element 89 into linearly polarized light which is rotated by 45° for the subsequent amplitude pixel Ap which is the second pixel in the composite pixel pair. After the light is incident on the amplitude pixel Ap, it is amplitude modulated and exits the SLM through a polarizer 84 arranged in the light exit plane of the SLM. After passing through the SLM, the light propagates in the direction of a field lens 89 which can be, for example, a volume grating or a stack of volume gratings or polarization gratings. The field lens 89 can be, in particular, a combined field lens which can have at least one volume grating and focuses the light exiting from the SLM, i.e. the light modulated with the information of the object or scene to be represented, onto a focal plane in the viewing region. The field lens 89 provides a virtual viewing window VW at the entrance plane of the observer's eye 90 through which the observer can view the represented scene or the represented object. In the case of eye movement and / or observer movement to a different position, vertical and / or horizontal tracking of the light can be provided using a vertical tracking device 91 and / or a horizontal tracking device 92. The tracking devices 91 and 92 can preferably comprise liquid crystal gratings.

[0219] If the light exits the SLM with an appropriately sized tilt angle, for example about 30°, a field lens based on an off-axis volume grating can be used. This means that no additional volume grating needs to be installed upstream of the field lens. This is only the case when a combined field lens as described above is used. The combined volume grating field lens has a first volume grating which achieves a plane-to-plane reconstruction which can be, for example, a 0° (on-axis) to 30° tilted through plane light wave. The second volume grating has a reconstruction of the 30° plane light wave with respect to the on-axis field lens. The combination of the two volume gratings forms an on-axis volume grating field lens, referred to as a combined field lens.

[0220] A variety of liquid crystal modes can be used in the display device, for example a TN (twisted nematic) mode or an in-plane mode whereby a rotation of the liquid crystal in the plane is achieved, for example a HAN mode.

[0221] The SLM or spatial light modulation device according to the application can be designed, for example, as a liquid crystal (LC) based spatial light modulation device or a multiple quantum well (MQW) based spatial light modulation device.

[0222] The application is not limited to the exemplary embodiments shown here. Furthermore, other embodiments or exemplary embodiments described and combinations of exemplary embodiments are possible. Finally, it should be expressly pointed out that the exemplary embodiments described above are primarily intended for describing the application, but the application is not intended to be restricted to the exemplary embodiments.

Claims

1. Light modulation device comprising: - pixels, substantially half of the pixels being designed as reflective pixels, the other half of the pixels being designed as transmissive pixels, the reflective pixels being arranged alternately with the transmissive pixels on the same substrate plane, - a backplane comprising transistors and data lines for conducting signals to the pixels, each pixel being assigned at least one transistor and at least two data lines, the transistors and data lines of each adjacent pair of pixels consisting of a reflective pixel and a transmissive pixel being arranged below the reflective pixel, - wherein two polarizers are provided, one polarizer being arranged in the light entrance plane area of the light modulation device, the other polarizer being arranged in the light exit plane area of the light modulation device, - wherein the polarizer provided in the light entrance plane area of the light modulation device is configured to be transmissive for one prescribed polarization and reflective for the other prescribed polarization, and - wherein the distance between the polarizer provided in the light entrance plane area of the light modulation device and the mirror elements of a mirror system in the reflective plane is set to a value which is almost the same as the thickness of at least one substrate between the mirror elements of the mirror system and an addressable transmissive layer having the pixels.

2. The optical modulation device of claim 1, wherein, - provided with at least one transparent substrate and the addressable transmissive layer, the addressable transmissive layer forming the pixels as modulation elements for modulating the incident light.

3. The light modulation device of claim 2, wherein, - the addressable transmissive layer is designed as a liquid crystal layer containing liquid crystal molecules.

4. The optical modulation device according to claim 1 or 2, wherein - the reflective pixels are designed as phase pixels and the transmissive pixels are designed as amplitude pixels.

5. The optical modulation device according to claim 1 or 2, wherein - the reflective pixels have a reflective layer provided at the back end of the reflective pixels in the direction of light propagation.

6. The optical modulation device according to claim 1 or 2, wherein - the backplane has a black mask assigned to the transistors and the data lines, the black mask being configured such that the black mask does not cover the edge area of the aperture of the pixels over the entire extension.

7. The light modulation device of claim 6, wherein, - the pixels are designed in a rectangular manner, the aperture of the pixels being confined at two opposite sides and not confined at the other two opposite sides.

8. The optical modulation device of claim 2, wherein, - one side of the at least one transparent substrate has the addressable transmissive layer containing the pixels, the opposite other side has a plane designed as the reflective plane.

9. The light modulation device of claim 8, wherein, - the reflective plane comprises a mirror system at which light is reflected between the reflective pixels and the transmissive pixels.

10. The optical modulation device of claim 9, wherein, - the mirror system comprises mirror elements which are designed to be reflective on one side towards the addressable transmissive layer containing the pixels or which are designed to be reflective on both sides towards and away from the addressable transmissive layer containing the pixels.

11. The optical modulation device of claim 10, wherein, - the mirror elements of the mirror system are arranged relative to the reflective pixels and the transmissive pixels such that each mirror element covers a part of the reflective pixels and a part of the transmissive pixels.

12. The light modulation device of claim 2, wherein, - the addressable transmissive layer is coupled to the reflective plane such that the incident light passes the reflective pixels and the transmissive pixels of the addressable transmissive layer, between which the reflective plane reflects.

13. The light modulation device of claim 1, wherein, - provided with unstructured delay elements.

14. The light modulation device of claim 13, wherein, The non-structured retardation element is arranged in the reflection plane and is configured to set a polarization of light for a second passing pixel of a pixel pair when the incident light passes through an adjacent pixel pair consisting of a reflection pixel and a transmission pixel, the reflection pixel and the transmission pixel being designed as phase pixel and amplitude pixel and jointly forming a composite pixel pair.

15. The light modulation device according to any one of claims 13 and 14, wherein, The non-structured retardation element is designed as a quarter wave plate or an eighth wave plate.

16. The light modulation device of claim 1, wherein, A compensation retardation element is provided.

17. The light modulation device of claim 16, wherein, The compensation retardation element is a non-structured compensation retardation element and is designed as a quarter wave plate or an eighth wave plate, the compensation retardation element interacting with the non-structured retardation element such that light incident on a first passing pixel of a pixel pair has a desired polarization.

18. The light modulation device of claim 16 or 17, wherein, The non-structured retardation element and the compensation retardation element have the same optical axis direction or their optical axes are rotated by 90° with respect to each other.

19. The light modulation device of claim 1, wherein, The polarizer provided in the light exit plane area of the light modulation device is configured as a wire grid polarizer.

20. The light modulation device of claim 1, wherein, The orientation of the liquid crystal molecules of the pixels is set such that the orientation of the liquid crystal molecules of the transmission pixel is rotated by 45° with respect to the orientation of the liquid crystal molecules of the reflection pixel.

21. The light modulation device of claim 1 or 20, wherein, The polarization direction of the polarizer provided in the light exit plane area of the light modulation device is rotated by 90° with respect to the polarization direction of light incident on a first pixel of a pixel pair consisting of a reflection pixel and a transmission pixel when passing through the pixel pair.

22. The light modulation device of claim 21, wherein, In each case, the undesired diffracted light incident on a pixel adjacent to a pixel to be modulated can be filtered by the polarizer provided in the light exit plane area of the light modulation device.

23. The light modulation device of claim 22, wherein, In each case, the undesired diffracted light incident on a pixel adjacent to a pixel to be modulated can be filtered by the polarizer provided in the light exit plane area of the light modulation device depending on the amplitude value of the adjacent pixel.

24. The light modulation device of claim 1, wherein, A color filter device is provided, the color filter device having color filters of the primary colors RGB, each color filter being assigned to the pixels alternately.

25. The light modulating device of claim 24, wherein, Each color filter is assigned to the pixels such that a composite pixel pair consisting of a reflection pixel and a transmission pixel has color filters of the same color, adjacent composite pixel pairs consisting of a reflection pixel and a transmission pixel have color filters of different colors.

26. The light modulation device of claim 1, wherein, The light modulation device is configured as a liquid crystal (LC) based spatial light modulation device or a multiple quantum well (MQW) based spatial light modulation device.

27. A display device comprising an illumination device and a light modulation device according to any one of claims 1 to 26.

28. The display device of claim 27, wherein, The illumination device provides oblique illumination of the light modulation device.

29. The display device of any one of claims 27 and 28, wherein, A field lens is provided, the field lens being designed as a single component or a combined field lens.

30. The display device of claim 29, wherein, The combined field lens comprises at least one volume grating.

31. The display device of any one of claims 27 or 28, wherein, At least one tracking device is provided.

32. The display device of claim 31, wherein, The at least one tracking device comprises at least one liquid crystal grating and / or at least one mirror element.

Images