Haptic Hologram

Abstract

The present invention relates to a system for generating haptic perception and holographic representations. The system comprises a light source for emitting light and a body comprising a substrate and at least one holographic optical element. The light source and the body comprising the holographic optical element are designed to generate a holographic representation in an interaction area. At the same time, the system comprises one or more acoustic transducers for emitting sound waves in the direction of the interaction area, whereby pressure variations in the interaction area can be perceived haptically. The system is characterized in that a substrate is arranged between the one or more acoustic transducers and the interaction area and has an audio channel in the form of an opening through which sound can propagate. The present invention also relates to the use of the system according to the invention for generating holographic representations and haptic perceptions.

Description

[Technical Field]

[0001] In a first aspect, the present invention relates to a system for generating haptic sensations and holographic images. The system includes a light source that emits light and a body that includes a substrate and at least one holographic optical element. The light source and the body that includes the holographic optical element are designed to generate a holographic image in an interaction area. At the same time, the system includes one or more acoustic transducers that emit sound waves in the direction of the interaction area, causing pressure variations in the interaction area to be tactilely perceived by the haptic sense.

[0002] The system is characterized in that the substrate is disposed between the acoustic transducer or transducers and the interaction area and includes an audio channel formed as an opening through which audio can propagate.

[0003] In another aspect, the invention relates to the use of a system according to the invention for generating holographic images and haptic perceptions. [Background technology]

[0004] Holography is a branch of optics that deals with the creation and construction of three-dimensional real images and can be considered an extension of photography. While photographic images are only two-dimensional representations of an object, holography leads to three-dimensional recording. In this regard, different types of recording of the object become available. In photography, for example, film shows the intensity of light reaching the film at each point. In contrast, in holography, additional optical information of the object is considered based on the wavefront emanating from the object, in particular amplitude and phase. Other information that can be registered in holographic recordings relates to the color spectrum and polarization, which opens up a wide range of design options. Traditionally, a recorded image is called a hologram, and an image generated based on a hologram by appropriate reconstruction is called a holographic image.

[0005] The development of holography technology allows holographic images to be freely generated and displayed in space. This process typically utilizes holographically generated microstructures, which are used to deflect light with a specific wavelength spectrum or at a specific angle of incidence. To the observer, real objects or animations can appear freely in space. In this regard, we refer to the real image seen in the holographic eyebox. Compared to two-dimensional images on a display, such representations have the advantage of being viewable from different sides, allowing the user to observe the holographic image from various viewpoints, resulting in a realistic image.

[0006] Additionally, it would be advantageous if such holographic images could be perceived or "felt" in space by force sensations. Particularly within the context of human machine interfaces (HMIs), this would be advantageous in that it would allow for optical perception and simultaneous tactile feedback. For example, holographic operating elements (keys, buttons, etc.) would be recognizable and could not only be optically displayed but also simultaneously be felt by the user.

[0007] To provide haptic feedback, the prior art discloses the use of an ultrasonic generator that can output perceptible feedback to a user using ultrasound. To this end, an ultrasonic signal can be amplitude-modulated at a low frequency and incident on the user's skin. The ultrasonic signal acts as a pressure variation on the skin, which can be perceived by the sense of force.

[0008] For example, U.S. Patent No. 9,612,658 B2 discloses a device for generating a sound field for tactile sensation. To this end, a user's hand, which is to perceive tactile signals, can be held over an electronic visual display. An array of ultrasonic transducers is positioned below the electronic visual display to generate a sound field corresponding to the information on the electronic visual display. The hand movement can be tracked by a hand tracker to enable appropriate pressure perception in different areas.

[0009] WO 2014 / 181084 A1 also discloses a device for generating a sound field by means of an array of ultrasonic transducers, for which a method is proposed for generating points in the sound field, which have a certain spatial relationship with respect to each other or with respect to the array.

[0010] DE 102017116012 A1 discloses a display device that, in addition to outputting an optical image, can additionally provide tactile feedback by generating a sound field. The display device includes an optical display having a plurality of pixels that creates an optical image on the front surface of the display device.

[0011] A plurality of acoustic transducers, preferably disposed on the rear surface of the display, are provided to generate a tactile sound field in the space in front of the display. In a preferred embodiment, control signals for the acoustic transducers are pre-distorted based on the acoustic characteristics of the display, thereby ensuring compensation or mitigation of acoustic distortions caused by the display. An alternative embodiment provides a display whose pixels include acoustically transparent areas adjacent to three sub-pixels of RGB colors. Preferably, the acoustic transducers are aligned with the acoustically transparent areas such that each acoustic transducer at least partially covers the acoustically transparent area. In this embodiment, the resulting size and location of the acoustically transparent areas are dictated by the pixel array of the display, which has a detrimental effect on the flexible generation of the sound field in the space in front of the display.

[0012] With regard to the combination of holographic images and haptic feedback, the prior art has so far disclosed only sporadic attempts, particularly with regard to the provision of operating elements in automobiles.

[0013] For example, German Patent Publication No. 102016214478A1 discloses a holographic display attached to the steering wheel of a car. Haptic feedback when the holographic display is operated can be achieved by ultrasonic pulses. When ultrasonic pulses are focused at the position in the holographic display operated by the user, this can provide the user with haptic feedback that can mimic the presence of an actual button. For example, an ultrasonic array for generating the ultrasonic pulses can be located in the steering column and / or in the dashboard area.

[0014] German Patent Application Publication No. 2016210213A1 describes a method for interaction between a vehicle occupant and an operating element. For this purpose, ultrasonic pulses, which can be arranged in an array, are generated by a plurality of ultrasonic transducers whose modulated individual signals are constructively superimposed on the surface of a virtual object, allowing for a haptic experience. For example, the virtual object can constitute an operating device. In this way, the user's operating gestures can be performed freely in space within the scope of highly automated driving operations and can be linked to haptic sensations.

[0015] German Patent Application Publication No. 102017211378A1 discloses a user interface for an automobile, including a display device with a holographic device. The holographic device generates representations freely in space, called holograms. The user interface may include an ultrasonic speaker mechanism for generating ultrasonic pulses on the user's skin that can be experienced by force. Thus, the user can feel a perceptible excitation from the ultrasonic waves, thereby providing haptic feedback when touching the hologram. The user should not be too distracted because they receive direct feedback from interacting with the hologram.

[0016] However, the devices and methods for haptic perception of holographic images known from the prior art at the moment have several drawbacks.

[0017] In particular, incorporating the components necessary to provide tactile sensations such as holographic images into each vehicle system is complex, which has adverse effects on production costs and control.

[0018] Additionally, known systems have limitations regarding application options, stemming from the inability to provide simultaneous haptic sensations and holographic representations with certain interaction gestures. Summary of the Invention [Problem to be solved by the invention]

[0019] It is an object of the present invention to provide a system for the haptic perception of holographic images that avoids the drawbacks of the prior art, in particular a system for the haptic perception of holographic images that is characterized by a compact structure and an efficient generation of holographic images and haptic perceptions with many interaction options, preferably using simple and cost-effective means. [Means for solving the problem]

[0020] The object is achieved by the features of the independent patent claims. Preferred embodiments of the invention are set forth in the dependent claims.

[0021] In a first aspect, the present invention relates to a system for generating haptic perception and holographic images in an interaction area, comprising: a. a light source that emits light; b. a body including a substrate and at least one holographic optical element, the light source and the body configured to generate a holographic image within an interaction area; c. one or more acoustic transducers that emit sound waves in the direction of the interaction area such that pressure variations are haptically tactile within the interaction area; Including, The method is characterized in that a substrate is disposed between the acoustic transducer or transducers and the interaction area, the substrate includes one or more audio channels, and the acoustic waves propagate at least partially through the one or more audio channels in the direction of the holographic image.

[0022] In particular, a compact structure of the system is made possible by the arrangement of the components, in particular by placing the substrate between the acoustic transducer and the interaction area. For example, the acoustic transducer can be located directly behind the body containing the holographic optical element. There is no need to integrate the components separately in different areas of the application system, e.g., in a vehicle.

[0023] Locating the components for generating the holographic image and haptic sensation on the optical and acoustic axes further avoids adverse shadowing effects that, for example, would impair the generation of the holographic image or haptic sensation when a manipulation gesture is performed in the interaction area. Instead, both the propagation of light for generating the holographic image and the propagation of sound for generating the haptic sensation in the interaction area are implemented to originate from the substrate or body.

[0024] Access to the interaction area is advantageously possible from either the front of the body or the substrate, which may not compromise the quality of the holographic image or haptic sensation.

[0025] Providing acoustic transducers behind the body or substrate relative to the interaction area does not attenuate the haptic experience here at all. Instead, the audio channel according to the invention ensures that the sound waves emitted by one or more acoustic transducers propagate in the direction of the holographic image with little distortion or attenuation, thereby enabling optimal haptic sensing thereof. In particular, acoustic waves are advantageously used in a particularly efficient manner, since the audio channel prevents any obstructions to the propagation of the sound waves.

[0026] Furthermore, there is a great deal of freedom in the design of the substrate for providing the acoustic waves. In particular, materials such as optical glass or plastic can be used that are optimized for manipulating light to generate holographic images but that can prevent the propagation of sound. Additionally, the substrate can be selected to have the desired rigidity so that there is no significant loss of pressure and / or intensity in the acoustic waves, and therefore no degradation of the haptic perception. Instead, it may be preferable to introduce a suitable sound channel into the substrate, the shape and / or size of which can be optimized according to the optical requirements, without at the same time accepting a degradation in the quality of the provided haptic experience.

[0027] It is also advantageous that the system according to the present invention can generate precise, specifically targeted pressure maxima and minima in the interaction region. Therefore, appropriate positioning of the audio channels can be used to ensure that desired pressures are obtained through interference in specific areas of the interaction region. As a result, the placement of the audio channels themselves can be used to create the desired constructive or destructive interference for generating pressure fluctuations that enable the haptic perception of holographic images.

[0028] The system according to the invention has proven particularly advantageous in the field of human-machine interaction (abbreviated as HMI). Therefore, information in the form of haptic feedback is transmitted particularly effectively by sound waves, which preferably propagate in the direction of the holographic image. In combination with the holographic image, various information can be provided in the process. Advantageously, operations can be designed safer and more efficiently with haptic feedback. For example, operations can be performed at least partially without vision, since the user experiences feedback regarding the operation and / or the operating element through the sense of touch. This increases safety, especially when using means of transportation, such as automobiles.

[0029] Furthermore, the system according to the invention can advantageously be provided in a particularly simple, compact and cost-effective manner.

[0030] In the context of the present invention, a holographic image preferably refers to an optical image generated with the aid of a holographic optical element. In this context, it can refer to any desired content, such as information, animation, or the projection of an object or operating element. In a preferred embodiment, the holographic image can be a three-dimensional projection of an object freely present in space, particularly within an interaction area. The holographic image can represent the object statically or dynamically. In this embodiment, the object preferably appears to the observer freely in space, i.e., preferably at a distance in front of the body. In this regard, this preferably relates to a real image visible within what is known as the holographic eyebox. Compared to a two-dimensional image formed on a display, such a representation advantageously can be viewed from different sides. Therefore, the observer can preferably observe the holographic image from different perspectives, resulting in a realistic view. In a preferred embodiment, the holographic image can appear at a distance of 1 mm, 2 mm, 5 mm, 10 mm, 2 cm, 5 cm, or more in front of the body comprising the substrate and at least one holographic optical element.

[0031] In another embodiment, the holographic image can be generated on a projection surface, which can be transparent, partially transparent, or opaque. For example, but not limited to, the holographic image can represent a control field, a joystick, a keyboard, and / or a trackball.

[0032] In general, haptic perception preferably refers to the active sensing of the size, color, texture, temperature, and / or mass of an object using the surface sensation of the skin, while tactile perception relates to the passive perception of mechanical stimuli. Surface sensation of the skin preferably refers to the skin's sensation of external stimuli imparted by receptors. In particular, this includes, among others, the sense of touch provided by mechanoreceptors. In a preferred embodiment, haptic perception may involve sensing an actual holographic image, e.g., its contour. However, it may also be preferable for local pressure fluctuations for haptic / tactile perception to be generated only spatially near the perceptible holographic image. For example, it may be preferable to project a holographic image onto a screen to generate a haptic perception above the screen, the perception corresponding to optical content projected onto the screen (e.g., into the manipulation field).

[0033] In the context of the present invention, the terms "haptic perception," "tactile perception," "haptic feedback," "force sensation," "haptic signal," and / or "haptics" can be used synonymously and can particularly refer to perceptions that can be imparted by (ultrasonic) pressure fluctuations in the air.

[0034] Preferably, the interaction area refers to a spatial region where a holographic image is optically perceived by a user and simultaneously allows haptic / tactile perception. Preferably, the interaction area can be increased or decreased in size depending on the respective arrangement of the system's components and / or the settings made. For example, it is known that sound intensity decreases in proportion to the square of the distance. For example, a specific arrangement of acoustic transducers can also increase the interaction area. A specific arrangement of audio channels can also increase the interaction area. Therefore, the interaction area can be reduced in size by the opposite. In addition, the interaction area can be increased or reduced in size depending on the positioning of light sources and / or holographic optical elements.

[0035] In another preferred embodiment, the interaction area may include an eyebox. Preferably, the eyebox refers to a plane or spatial area in which the holographic image is perceivable as a virtual image by a viewer or user. The virtual image plane, i.e., the plane in which the virtual image is generated, may be located on or behind the projection surface.

[0036] The light source includes any type of light emitting means used to convert electrical energy into light. The light source is preferably configured to emit light in the direction of the body. In particular, the body and the light source are designed to generate a holographic image. Preferably, providing the holographic image is performed by at least one holographic optical element.

[0037] Therefore, light emitted from the light source can be made to enter the light entrance region. Preferably, the light entrance region refers to the region on the substrate where the light enters the substrate. The light re-emerges at the light exit region to generate the holographic image. Similar to the light entrance region, the light exit region refers to the region on the substrate where the light emerges to generate the holographic image.

[0038] In the sense of the present invention, a holographic optical element (abbreviation HOE) preferably denotes a component that is provided holographically and performs an optical function. In a preferred embodiment, the at least one holographic optical element is a hologram that performs a specific optical function. Thus, the beam path of light incident on the body is influenced by the at least one holographic optical element. For example, the optical function can be transmission, reflection, diffraction, scattering, and / or deflection of light. Advantageously, holographic optical elements can be manufactured in a cost-effective manner. Furthermore, holographic optical elements are robust, not prone to failure, and stable over time. Furthermore, the at least one holographic optical element is characterized in that it can be designed to be particularly flat and therefore requires very little space.

[0039] The at least one holographic optical element is preferably designed to perform an optical function for multiple wavelengths, and for this purpose, for example, multiple holograms, each diffracting light of, for example, one wavelength, and / or multiple holograms diffracting light of multiple wavelengths, can be arranged in a hologram stack.

[0040] Preferably, the holographic image is generated in front of the body. The phrase "in front of" preferably refers to the area including the interaction area. Preferably, the acoustic transducer is behind the substrate. The phrase "behind" preferably refers to being located within the area where the acoustic transducer is present. These areas can also be described in terms of "front area" and "rear area" in the context of the present invention. In particular, the interaction area is in front of the substrate. Preferably, the front area and the rear area are separated from each other by the body.

[0041] In a preferred embodiment, the light source can be positioned in front of the substrate, so that light emitted from the front region reaches the surface of or within the body. When the light source is positioned in front of the substrate, it may be preferable that at least one holographic optical element includes a reflection hologram that reflects light rays incident from the front to generate a holographic image in the front region. Similarly, it may be preferable that at least one holographic optical element includes a transmission hologram, so that light rays from a front spatial direction initially pass through the transmission hologram without being diffracted. Preferably, the light rays can be reflected by the substrate or by another reflection hologram and then incident on the transmission hologram from the rear. Various combinations of reflection and / or transmission holograms are conceivable and can be used in the configurations according to the invention.

[0042] In a preferred embodiment, the light source can be positioned behind the substrate, so that light emitted from the rear region reaches the surface of or within the body. When the light source is positioned behind the main substrate, it may be preferable for at least one holographic optical element to include a transmission hologram that transmits light rays incident from the rear to generate a holographic image in the front region. Similarly, it may be preferable for at least one holographic optical element to include a reflection hologram, preferably such that light rays from a rear spatial direction initially pass through the reflection hologram without diffraction. Light rays can be reflected at the substrate or by another reflection hologram and then guided to the reflection hologram from a front direction. Various combinations of reflection and / or transmission holograms are conceivable and can be used in the configurations according to the present invention.

[0043] Furthermore, it may be preferable for the light source to be positioned so that the light beam is emitted at the edge of the main substrate, corresponding to an edge-lit configuration, in which case it may also be preferable to utilize a transmission hologram, a reflection hologram, or a combination of transmission and reflection holograms.

[0044] Furthermore, the at least one holographic optical element may be connected to the surface of the substrate. For example, the connection may be made by adhesive bonding and / or lamination. Furthermore, it is preferred that the at least one holographic optical element is connected to the substrate as a film. For example, the film may also be connected to the substrate only in a portion of the light entrance region and / or the light exit region. In an alternative embodiment, the connection between the at least one holographic optical element in the form of at least one film and the substrate may be formed over substantially the entire area.

[0045] In particular, the at least one holographic optical element is configured to modify the beam path of light, for example, by diffraction, reflection, transmission, and / or refraction. In a preferred embodiment, the at least one holographic optical element comprises a hologram. Rather than by the geometry of a transmitting or reflecting object, as is the case with lenses or mirrors, the at least one holographic optical element preferably modifies the light in the beam path by information stored in a hologram, for example, by a change in refractive index. In this case, the hologram used for the at least one holographic optical element is preferably not generated as an image of an actual object, but is preferably generated as a superposition of various planar or spherical light waves, the interference pattern of which produces the desired optical effect.

[0046] Preferably, at least one holographic optical element includes one or more holograms, each hologram being recorded at at least one predetermined wavelength. A holographic optical element may include, for example, multiple holograms, which may be arranged one above the other as a stack. For example, a holographic optical element may have multiple, preferably multiple, monochromatic holograms. Alternatively, a holographic optical element may include at least one hologram recorded at at least two predetermined wavelengths. Preferably, such holograms are recorded at three wavelengths in a predetermined color space, e.g., configured as an RGB hologram or a CMY hologram, or a hologram formed from multiple individual wavelengths in different color spaces. In these examples, R is red, G is green, B is blue, C is cyan, M is magenta, and Y is yellow.

[0047] Preferably, the at least one holographic optical element comprises a material selected from the group comprising photosensitive glass, dichromated gelatin, photopolymer, polycarbonate, and / or triacetate, in particular, these materials can be attached to the film and / or formed or provided as the film itself.

[0048] The body preferably comprises a substrate and at least one holographic optical element. For example, the substrate can be a circular or square wafer with a thickness in the centimeter, millimeter, or submillimeter range. The at least one holographic optical element is preferably connected to the surface of the substrate, i.e., the front and / or rear surface, or embedded in the substrate. The front and / or rear surfaces of the body can be in the form of planar surfaces. In this regard, the body can be in the form of, for example, a plane-parallel plate or a wafer. However, it is also possible to have embodiments in which the front and / or rear surface is curved. The body can comprise glass and / or plastic. Furthermore, the body can be monolithic or multilayered. The body can also be transparent or partially transparent. In particular, the substrate can also have a transparent or partially transparent embodiment. Preferably, the transparent or partially transparent body and / or substrate can transmit light from the light source.

[0049] In the sense of the present invention, an acoustic transducer preferably refers to a device that converts an electrical signal, in particular an acoustic signal. In particular, an acoustic signal refers to the controlled emission of sound waves. Therefore, in the context of the present invention, an acoustic transducer serves as a sound source.

[0050] In the sense of the present invention, an audio channel refers in particular to an opening in the substrate, through which audio can propagate in the interaction area in the direction of the holographic image. The audio channel or opening preferably extends from the rear surface to the front surface across the entire thickness of the substrate, or preferably over at least 50%, 60%, 70%, 80%, 90% or more of it. The opening is characterized by the absence of substrate material. The opening can be substantially filled with air. It may be preferable to introduce a different medium, preferably a sound-conducting medium, into the opening to form the audio channel.

[0051] Advantageously, sound pressure, and in particular fluctuations in sound pressure, can be sensed within the interaction area, thereby advantageously making the holographic image haptically perceptible. The haptic perception of the holographic image can be tailored by the placement, number, shape, and / or size of the openings depending on the application.

[0052] Advantageously, sound propagation for generating haptic sensations and light propagation for generating holographic images can be implemented along the optical or acoustic axis.

[0053] The prior art does not disclose such an arrangement because optical components have adverse transparency properties for sound, especially ultrasound: for example, glass and / or plastic as substrate materials are substantially opaque to sound waves, so that compact placement of an acoustic transducer on the optical axis behind the substrate did not appear to be feasible without adverse effects on haptic perception.

[0054] In contrast, the inventors have realised that by providing an audio channel within the substrate, audio, and in particular ultrasound, can advantageously be guided undistorted through the same (optical) substrate that produces the holographic image.

[0055] In another preferred embodiment, the system is characterized in that it is designed to generate holographic images by means of transmission and / or reflection holograms.

[0056] The at least one holographic optical element is preferably a reflection hologram and / or a transmission hologram. Preferably, the at least one holographic optical element performs an optical function, such as transmission and / or reflection. Advantageously, this allows for various geometric arrangements of the light source, body, and acoustic transducer components for generating a holographic image and, in particular, a haptic sensation in the interaction area. Advantageously, this also allows for adjusting the interaction area and optimizing it depending on the application and installation space. Advantageously, a user can move to multiple positions and simultaneously sense the holographic image optically and haptically.

[0057] The name of the type of hologram contained by the at least one holographic optical element preferably provides an indication as to the optical function performed and as to the arrangement of system components for reproducing the hologram.

[0058] A reflection hologram is a reflection hologram that reflects light incident from a light source, thereby functioning like a mirror. In the case of a reflection hologram, the light source can be located in front of or behind the substrate. For example, it may be preferable to place the light source in front of the substrate and direct its light emission from this front spatial direction to the reflection hologram. As a result, when a reflection hologram is used, the light entrance area and the light exit area may be the same, i.e., light rays enter the exit hologram through the light entrance area, are reflected by the reflection hologram, and re-emerge from the same area to display a holographic image. Similarly, it may be preferable to place the light source behind the substrate and direct its light emission from that spatial direction initially through the reflection hologram without diffraction. The light may preferably be reflected by the substrate or by another reflection hologram and then enter the reflection hologram from the front direction.

[0059] For a given wavelength, reflection holograms advantageously accept a wider angular spectrum with high efficiency and higher wavelength selectivity, so that colors can be separated from each other despite the wide angle of the incident spectrum. In particular, they advantageously allow a wide field of view for the holographic image and at the same time high illumination efficiency.

[0060] In some embodiments, it may be preferable to arrange two reflection holograms in series in the beam path, with the light source preferably located behind the substrate. The first reflection hologram allows light waves from the light source to pass substantially undiffracted to the second reflection hologram behind the first. The second reflection hologram reflects or diffracts the light back to the first reflection hologram, where it is reflected or diffracted to generate a holographic image in front of the substrate. As a result, reflection holograms arranged in this manner allow for a configuration similar to that of a transmission hologram, while still providing the aforementioned advantages of reflection holograms.

[0061] In the case of a transmission hologram, light from the light source is transmitted. When a transmission hologram is used, the light source is preferably located in front of or behind the substrate. For example, it may be preferable to locate the light source behind the substrate and direct its light emission toward the transmission hologram, which diffracts light rays from this spatial direction behind. In this case, the light entrance and light exit areas are particularly located on opposite sides of the substrate. Similarly, it may be preferable to locate the light source in front of the substrate and initially direct its light emission from that spatial direction through the transmission hologram without diffraction. Preferably, the light can be reflected within the substrate and then enter the transmission hologram from the rear direction and be diffracted by the transmission hologram, so that the holographic image is generated in the front area. To avoid color distortion, a transmission hologram may be preferred. Furthermore, holographic images from transmission holograms advantageously have a large depth of field, i.e., the distinguishable area is extended, especially when observation is in focus.

[0062] In another preferred embodiment, the system is designed to generate a holographic image using an edge-lit configuration. Preferably, the edge-lit configuration refers to the emission of light to the edge or peripheral region of the substrate and the emission of light to generate a holographic image in the front region. In the edge-lit configuration, at least one holographic optical element can preferably be embedded on or within the substrate for this purpose. Furthermore, the at least one holographic optical element can be a reflection hologram and / or a transmission hologram, even in the edge-lit configuration. Preferably, the substrate is designed as a light guide when an edge-lit configuration is used. As a result, illumination from the light source can propagate light within or through the substrate by reflection, preferably by total internal reflection, and a holographic image can be displayed in the interaction area.

[0063] It is particularly advantageous when an edge-lit configuration is used that the light source can be integrated into the body and / or substrate itself, thereby ensuring a particularly compact and carefully aligned display of the holographic image. In particular, the holographic image can appear particularly sharp, so that the viewer experiences a particularly realistic image of the object. The use of reflection holograms for this purpose can be preferred, as these can be used to optimize brightness and sharpness of contours for a particularly realistic display.

[0064] The edge of the substrate preferably refers to a lateral region of the substrate having a thickness substantially smaller than the length and / or width of the substrate. For example, the thickness of the edge can be about 0.2 mm, about 0.5 mm, about 1 mm, 5 mm, 10 mm, or 50 mm. In this case, the ratio of the thickness to the length and / or width of the edge of the substrate can be greater than 1:10, greater than 1:50, or greater than 1:100. In the context of the present invention, the terms substrate periphery and edge can be used synonymously.

[0065] In another preferred embodiment, the system is characterized in that the substrate comprises an in-coupling region and an out-coupling region at different locations on the substrate, and light propagates within the substrate between the in-coupling region and the out-coupling region by reflection, preferably by total internal reflection.

[0066] As a result, the substrate advantageously also functions as a light guide, through which light can propagate to provide a holographic image in the interaction area. In this regard, the terms "in-coupling area" and "out-coupling area" are intended to describe the entrance and exit portions of the substrate when the substrate itself is designed as a light guide.

[0067] In this regard, the in-coupling region preferably refers to the region of the substrate that allows light to pass through the substrate and where the light is coupled into the substrate. Preferably, the in-coupling region may include a holographic optical element that is used to couple the light into the substrate.

[0068] The in-coupling region may also have a transparent or partially transparent configuration in some embodiments. For a desired transmittance, the in-coupling of radiation, e.g., by a diffractive structure, is precisely so efficient that sufficient radiant power is incident on the out-coupling region. A partially transparent in-coupling region may be implemented such that the in-coupling efficiency is, for example, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50% or more. In this case, the in-coupling efficiency refers to the proportion of light that can be transmitted and thus introduced into the substrate.

[0069] In particular, the in-coupling of light into the substrate refers to the incidence and propagation of light therein. The propagation of light within the substrate is preferably by reflection, particularly preferably by total internal reflection. By total internal reflection, in particular, the light is not emitted uncontrollably from the area, but is instead steered in a targeted manner towards the out-coupling area, and a holographic image is displayed in or from the area of ​​the out-coupling area.

[0070] The principle of total internal reflection can be illustrated by the incidence of light on an interface between two media. When a light beam passes from a first medium with a different optical density to a second medium, two phenomena can occur at the interface: either part of the light is refracted and enters the second medium, or part of the light is reflected and remains in the first medium. If the optical density of the first medium is higher than that of the second medium, the refracted beam will run parallel to the interface above a certain angle of incidence. If the angle of incidence becomes even larger, the light will no longer enter the second medium and the light beam will be totally reflected. This is called total internal reflection. In the context of the present invention, the term "total internal reflection" refers to total internal reflection within the substrate, which preferably functions as a light guide.

[0071] Total internal reflection can occur at the front surface, the rear surface, and within the substrate. It is also possible to provide a reflective or partially reflective layer or coating to propagate light within the substrate by reflection, preferably by total internal reflection.

[0072] Preferably, the propagation of light along or within the substrate can also be implemented using an edge-lit configuration. Preferably, in this regard, light enters at one edge of the substrate and propagates within the substrate, preferably to at least one holographic optical element, which may be, for example, a hologram. As a result of the effect of the HOE, the light preferably emerges in the out-coupling region to display a holographic image, preferably within the interaction region.

[0073] Preferably, the out-coupling region refers to an area of ​​the substrate as a light guide from which light is out-coupled to form a holographic image in the interaction region. Preferably, the out-coupling region may include a holographic optical element used to out-couple light from the substrate.

[0074] Like the in-coupling region, the out-coupling region can have a transparent or partially transparent form in some embodiments. For example, the out-coupling efficiency of the out-coupling region can be, for example, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50% or more. In this case, the out-coupling efficiency indicates the percentage of light that can be transmitted and therefore exit the substrate.

[0075] In another preferred embodiment, the system is characterized in that the in-coupling region is arranged around the periphery of the substrate and / or the in-coupling region comprises a first holographic optical element, and light can be in-coupled into the substrate and deflected within the substrate by the first holographic optical element.

[0076] Advantageously, the light beam path within the substrate can be precisely set by a first holographic optical element having an appropriate optical function to allow the light to propagate within the substrate. The first holographic optical element can be present on the front surface, rear surface, edge and / or within the substrate.

[0077] Preferably, the first holographic optical element is in the form of a reflection or transmission hologram. If the light in-coupling is implemented by an edge-lit configuration, it is also preferred that the first holographic optical element is a reflection or transmission hologram.

[0078] In another embodiment, the in-coupling region can include a diffractive structure, which is formed on the front and / or rear surface of the substrate. For example, the diffractive structure of the in-coupling region can be in the form of an embedded diffractive structure or a diffractive structure on the front or rear surface of the substrate. Similarly, the diffractive structure of the in-coupling region can include a transmissive or reflective relief grating.

[0079] In another preferred embodiment, the system is characterized in that the out-coupling region includes a second holographic optical element, and light for generating the holographic image in the interaction region exits through the out-coupling region.

[0080] Advantageously, the light is coupled out in a targeted manner by the second holographic optical element, so that a holographic image can be generated at a desired location within the interaction area. In another embodiment, the second holographic optical element can be in the form of a reflection or transmission hologram. Advantageously, the light enters the interaction area by reflection or transmission, such that a holographic image appears within the interaction area.

[0081] In another embodiment, the out-coupling region includes a diffractive structure. The diffractive structure of the out-coupling region can be in the form of an embedded diffractive structure or a diffractive structure on the front or rear surface of the substrate. In particular, a reflective or transmissive hologram can be provided as the diffractive structure. Furthermore, the diffractive structure of the out-coupling region can be a transmissive or reflective relief grating. The out-coupling region can also include mirrors, prisms, and / or reflective or transmissive Fresnel structures. These variations can be provided as an alternative to or in addition to the diffractive structure of the out-coupling region.

[0082] Preferably, the diffractive structure refers to an optical element for shaping a light beam emitted from a light source. Preferably, the diffractive structure comprises a microstructure, which is provided, for example, by photolithography. In the microstructure, the different optical path lengths of the component beams cause phase modulation, thereby generating an interference pattern. Additionally, the amplitude is modulated by constructive and destructive interference. Therefore, by clever design, the intensity pattern and / or path of the beam can be manipulated to generate a holographic image.

[0083] In another preferred embodiment, the system is characterized in that the system comprises 2, 3, 5, 10, 20, 50, 100 or more acoustic transducers, preferably arranged in an array.

[0084] The acoustic transducer is preferably configured to emit light waves in the direction of the holographic image. In particular, the acoustic transducer is preferably arranged "behind the substrate" in this case, i.e., the substrate is arranged between the interaction area and the acoustic transducer. Advantageously, the sound field can be generated within the interaction area by a plurality of transducers, in particular by an array. In this regard, the sound fields can be differentiated by pressure and / or intensity distribution, preferably providing different haptic sensations on the human skin in different areas of the holographic image. In particular, different forces act on the skin, reproducing the shape and / or structure of the object visualized by the holographic image through a haptic sensation. For example, the joystick and / or keyboard of a car can be represented as a holographic image. Touched areas of the joystick and / or keyboard keys can have different pressure and / or force sensations than other parts of these objects.

[0085] Preferably, one or more acoustic transducers are connected to one or more phase control components. Advantageously, the phase of the sound waves emitted by the acoustic transducers can be controlled in an open-loop and / or closed-loop manner by the phase control components. It is particularly advantageous here that the phase can be set such that pressure is maximized and / or minimized in specific regions of the holographic image and / or interaction area, thereby generating a particularly realistic haptic perception of the holographic image.

[0086] In another embodiment of the present invention, the acoustic transducer produces a predetermined distribution of pressure patterns that results in a first haptic sensation of the holographic image in one portion of the interaction area and a second haptic perception of the holographic image in another portion of the interaction area.

[0087] By providing different haptic sensations, a system according to the present invention allows a user to, for example, accurately position their hand to identify and / or embody a shape, structure, and / or input. Furthermore, the system can be configured to provide haptic feedback to the user, for example, when the user's hand is in the correct position for interaction with the holographic image. For example, vibrations can be transmitted when the user's fingers are placed over the play and / or pause controls or volume control areas of the keyboard of the holographic image. Alternatively, the perceived strength or intensity of the feedback can be increased. For example, there can also be haptic feedback when a control gesture ends. In particular, the system can be configured to register a user's gestures and / or controls on, within, and / or along the holographic image.

[0088] The acoustic transducers are preferably arranged in an array. In the sense of the present invention, an array refers to the arrangement, i.e., the geometric configuration, of the acoustic transducers. For example, the acoustic transducers can be arranged in one, two, or three dimensions. Preferably, the acoustic transducers are arranged in a grid and / or have a constant distance from each other. For example, the distance between the acoustic transducers can be up to about 250 mm, about 200 mm, about 150 mm, about 100 mm, about 50 mm, about 20 mm, about 10 mm, about 5 mm, about 2 mm, or about 1 mm.

[0089] In another embodiment, it may be preferable to use beamforming techniques for sound propagation, so that by controlling the phase control components, sound waves can be emitted in a directionally interfering manner, for example to obtain a specific pressure rise in a specific area.

[0090] Preferably, the system according to the invention comprises a control unit configured for closed-loop control of the phase, intensity, intensity distribution, pressure and / or frequency of the acoustic transducer. Advantageously, the acoustic transducer can emit over an angle along the plane of at most 180°, preferably at most 120°, particularly preferably at most 80°, very particularly preferably at most 50°, even more preferably at most 30°, very preferably at most 10°, so that the sound waves can be emitted in a particularly focused manner.

[0091] Advantageously, sound waves can pass through the substrate with little distortion by the audio channel, resulting in the user experiencing a particularly realistic haptic perception of the holographic image. For example, a desired pressure of 10-50 Pa (Pascals) can be achieved over an angular range of about 40-70° at a distance of about 10-40 cm. Audio parameter settings can preferably be set and / or controlled by a control unit.

[0092] Preferably, the system also includes a controller for controlling components of the system, such as the ultrasound transducer or the light source.

[0093] In the sense of the present invention, a control unit preferably refers to a computing unit such as a processor, processor chip, microprocessor, and / or microcontroller for automatically controlling the components of the system, e.g., the ultrasound transducer, by specifying parameters of the sound waves (e.g., phase, intensity, pressure, frequency, etc.). In another preferred embodiment, the control unit may be a computing machine, e.g., a computer, a computing device, or a computing system. The components of the controller may be configured conventionally or individually for the respective implementation. Preferably, the controller includes a processor, a memory, and computer code (software / firmware) for controlling the components of the device.

[0094] Preferably, the control unit may be a programmable circuit board, a microcontroller, or any other component for receiving and processing data signals from the components of the system, in particular the acoustic transducers or the light sources. Preferably, the control unit also includes a computer usable or computer readable medium, such as a hard disk drive, a random access memory (RAM), a read-on memory (ROM), a flash memory, etc., on which preferably the computer software or code is installed. The computer code or software for controlling the components of the system according to the invention may be written in any desired programming language or model-based development environment, such as C / C++, C#, Objective-C, Java, Basic / Visual Basic, MATLAB, Simulink, StateFlow, LabView, or Assembler.

[0095] The phrase "a controller is configured to perform certain operational steps, such as controlling the phase, intensity distribution, pressure, and / or frequency of an acoustic transducer," may include customer-specific or standard software that is installed on the controller and initiates and controls these operational steps.

[0096] In another preferred embodiment, the system is characterized in that the acoustic transducer is an ultrasonic transducer configured to emit sound in the frequency range of 20 kHz to 100 kHz, preferably 30 kHz to 60 kHz.

[0097] Particularly efficient haptic perception can be advantageously achieved as a result of the use of ultrasound transducers. Furthermore, ultrasound transducers have proven valuable in the technical field of haptic or tactile sensation projection for optimal and easy generation of haptic feedback. In this context, ultrasound transducers refer to acoustic transducers that emit ultrasound waves in a particular appropriate frequency range.

[0098] In another preferred embodiment, the system is characterized in that the pressure fluctuations are generated by acoustic sound waves with a carrier frequency and a modulation frequency, the carrier frequency preferably being between 20 kHz (kilohertz) and 100 kHz and / or the modulation frequency being in the range of 0.1 Hz (hertz) and 500 Hz, particularly preferably in the range of 150 Hz and 250 Hz, which can preferably be controlled by a control unit.

[0099] Modulation of acoustic waves with frequencies between 0.1 Hz and 500 Hz advantageously allows the user to perceive the holographic image particularly well haptically, in particular because the mechanoreceptors of the human skin are particularly sensitive to these frequencies. Holographic images can therefore be advantageously combined with particularly realistic haptic perception.

[0100] In another embodiment, the acoustic transducer can emit sound in such a way that control points are defined within the interaction area. Preferably, a control point refers to a marking at a specific location within the interaction area. The control point can be distinguished by an area assigned a specific amplitude and / or a specific phase. Therefore, the control point can also be modeled such that the acoustic transducer is positioned directly below the control point. Preferably, the spacing between the control points is such that it substantially corresponds to the wavelength of the sound. The control unit is preferably configured to define such control points within the interaction area. Advantageously, the control points can define shapes and / or portions of the holographic image. For example, a volume including multiple edges and / or corners can be modeled by the control points, resulting in the control points being located at the edges and / or corners, thereby perceiving a predetermined pressure. The control points can also define shapes that the user can feel as part of a haptic feedback system. Preferably, the user can perform interactions that can be felt within the area.

[0101] In another preferred embodiment, the system is characterized in that the light source is arranged in or outside the substrate, the light source preferably being a laser and / or an LED.

[0102] In particular, mounting the light source within the substrate advantageously results in a particularly compact design of the system according to the invention. As a result of this compact design, the system according to the invention can be integrated into a wide variety of possible applications. Mounting the light source outside the substrate is advantageous in that it allows for greater variety and flexibility in terms of the type of light source and the illumination and / or emission of the body and / or the substrate. For example, this relaxes the requirements for compactness of the light source and also allows the substrate to be mounted in different positions, if it is desired to direct a tailored angle of incidence of light towards the body and / or the substrate.

[0103] It is also preferred that at least one holographic optical element is implemented as a volume hologram at the front surface, the rear surface, and / or within the substrate. A volume hologram preferably refers to a hologram written in a relatively thick photosensitive layer. This can be preferably implemented by transmission or reflection techniques. Advantageously, a series of Bragg reflection surfaces is obtained as a result of the interference of the object and reference beams within the hologram volume. A volume hologram can therefore also be considered as a holographic grating, i.e., an optical grating generated by holography. As a result, a volume hologram advantageously has a non-negligible range of light beam propagation directions, and the Bragg condition applies when reconstructing the volume hologram.

[0104] For this reason, volume holograms have wavelength and / or angle selectivity. The ability of volume holograms to simultaneously store multiple images makes it possible, among other things, to create color holograms. A light source emitting the three primary colors blue, green, and red can be used to record the hologram. After exposure, three holograms are simultaneously stored in the volume hologram. Reconstruction of color holograms takes advantage of the fact that each partial hologram can only be reconstructed in the color in which it was recorded. Consequently, the reconstructed extracts of the three colors are superimposed, forming a faithful color image if the color components are correctly weighted.

[0105] Furthermore, the volume hologram has the advantage that it can deflect various light rays particularly precisely in the direction of the exit or output coupling area in the interaction area and / or deflect said light rays within the substrate in embodiments in which the substrate acts as a light guide.

[0106] In a preferred embodiment, the light source is coherent, particularly preferably partially coherent. A coherent light source is characterized by emitting a coherent light beam. Coherence preferably refers to the property of light waves in which the phase relationship between two wave trains is fixed. A fixed phase relationship between two wave trains allows for spatially stable interference patterns to be obtained. With regard to coherence, a distinction can be made between temporal and spatial coherence. Spatial coherence preferably represents a measure of the fixed phase relationship between wave trains perpendicular to the propagation direction and is obtained, for example, for parallel light beams. Temporal coherence preferably represents a measure of the fixed phase relationship between wave trains along the propagation direction and is obtained, in particular, for narrow-band, preferably monochromatic light beams.

[0107] Coherence length preferably refers to the maximum path length difference or time of flight difference that two light beams have from a starting point, during which a stable interference pattern (in space and time) is obtained while they are overlapping. Coherence time preferably refers to the time required for light to travel the coherence length.

[0108] In a preferred embodiment, the light source is a laser. Particularly preferably, this is a narrow-band, preferably monochromatic laser, with a preferred wavelength in the visible range (preferably 400 nm to 780 nm). Non-exhaustive examples include solid-state lasers, preferably semiconductor lasers or laser diodes, gas lasers, or dye lasers.

[0109] Other light sources, preferably coherent light sources, may also be preferably used.Narrow band light sources, preferably monochromatic light sources, including for example light emitting diodes (LEDs), optionally in combination with monochromators, are also preferred.

[0110] In particular, the use of LEDs is advantageous in that they are particularly compact and can be particularly easily integrated in a particularly cost-effective manner into the system according to the invention.

[0111] In another preferred embodiment, the system is characterized in that one or more audio channels are formed as openings in the substrate.

[0112] Advantageously, light can be transmitted in a targeted manner in or through the substrate, thereby generating a holographic image in the interaction area, and sound can similarly pass through the substrate via the apertures. In particular, the holographic image can be configured to be haptically perceptible in a particularly efficient manner. As a result, perforated substrates can be used to generate holographic images and can be combined with acoustic transducers to obtain haptic feedback.

[0113] In this case, a consideration regarding the distance between the acoustic transducer and the holographic image is that the sound intensity falls off in proportion to the square of the distance. Therefore, the acoustic transducer is preferably positioned so that pressure variations that can be felt on a person's skin reach the interaction area through the opening. In this regard, it may be preferable to position the sound channel directly next to and / or around the second holographic optical element.

[0114] By appropriately positioning the sound channels, particularly in the form of openings in the substrate, it is possible to advantageously generate sound pressure patterns that are suitable for being perceived as haptic signals. The sound pressure patterns can be distinguished by pressure maxima and / or minima within the interaction area, particularly along the holographic image. In particular, constructive and / or destructive interference can be used to generate pressure fluctuations at desired points, allowing forward-propagating wavefronts of the sound waves to cancel each other out. For example, it may be preferable for outward-propagating wavefronts to interfere destructively in the far area and constructively in the near area, particularly in the interaction area.

[0115] Advantageously, a defined pressure field buildup with respect to the pressure pattern can be obtained within the interaction area, in particular depending on the power of the acoustic transducer, and in particular therefore making it possible to generate different sound pressures in a very localized manner suitable for being perceived as haptic signals.

[0116] In another preferred embodiment, the system is characterized in that one or more of the sound channels have an oval and / or quadrilateral cross section.

[0117] Advantageously, the geometry of the sound channel can influence the propagation of sound waves and / or light.

[0118] An elliptical cross section of the sound channel is therefore advantageous in that the sound modes are only slightly affected. In particular, the sound modal spectrum is not modulated at all or only slightly. Preferably, a sound channel with an elliptical cross section allows particularly good and easy control of the passage of sound. In this case, it has been found that the more round the cross section of the sound channel, the larger the resulting modal spectrum. In particular, an elliptical cross section also includes the circular shape of the sound channel. Consequently, an elliptical cross section of the sound channel is particularly advantageous for the propagation of sound through the substrate.

[0119] However, for light rays passing through the sound channel, its elliptical cross section may cause these light rays to be refracted. In particular, the light rays may scatter outwards, where outwards preferably refers to beam paths that move away from the center of the light beam. Therefore, the elliptical cross section of the sound channel may act like a diverging lens for light passing through the sound channel in the substrate.

[0120] To compensate for the influence of the sound channel, it may be preferable to introduce a lens and / or a corresponding optical function, e.g., a holographic optical element with a lens function, which can advantageously refocus the outwardly scattered light so that the light is aligned in a targeted manner for the purpose of generating a holographic image. In a preferred embodiment, a holographic optical element with a focusing lens function is used to compensate for a sound channel with an elliptical cross section. In this case, the lens or holographic optical element with a focusing lens function can have an inverse optical function for the curved sound channel. Advantageously, light can pass through over many incident light angles and / or the color can appear correctly.

[0121] In contrast, a quadrilateral cross-section of the sound channel has been found to be particularly advantageous for the transmission of light rays within the substrate, since, with proper alignment, light is not or only very little refracted at the quadrilateral surface. In particular, it is preferred to use a gap as the sound channel. Preferably, a gap refers to a rectangular cross-section whose width in the direction of light propagation is significantly smaller than its length in the direction perpendicular thereto. For example, the gap can be narrower than its length by a factor of 3, 5, 10, or more. In particular, quadrilateral cross-sections also include rectangles, squares, trapezoids, parallelograms, and / or rhombuses. In other embodiments, the cross-section can also be a diagonal, triangular, pentagonal, hexagonal, heptagonal, octagonal, or other polygonal shape. This does not limit the geometric shape of the sound channel, particularly as an aperture in the substrate. A polygonal cross-section is advantageous in that it is easier to provide substantially right-angled interfaces through which light can be incident substantially perpendicularly, thereby advantageously minimizing aberrations.

[0122] In another preferred embodiment, the system is characterized in that one or more of the sound channels can have a tilt angle within the substrate, thereby allowing the sound waves to be focused onto the holographic image.

[0123] The sound channel preferably has a tilt angle when a line drawn at a point on the edge of the sound channel has a profile different from that of the longitudinal and / or lateral axes of the substrate. In the context of the present invention, this may also be called tilt. Advantageously, tilting the sound channel makes it possible to obtain a higher sound pressure in the interaction area. In particular, the holographic image can be perceived haptically with a higher intensity. It is particularly preferred that the acoustic transducer is also present in a tilted state. In this case, the sound pressure, and therefore the intensity, can be intensified to a particularly high degree, and haptic perception can be generated in particular detail. An acoustic transducer having substantially the same tilt angle as the tilted sound channel is particularly preferred.

[0124] In another preferred embodiment, the system is characterized in that the one or more audio channels partially or completely surround a light-injection region or an out-coupling region in the substrate, where surrounding preferably means that the one or more audio channels are arranged in a manner that surrounds the light-injection region or out-coupling region, and that the one or more audio channels are not arranged in the light-injection region or out-coupling region itself.

[0125] Advantageously, arranging the audio channel along the contour of the light emission region or output coupling region allows for particularly efficient provision of pressure fluctuations within the interaction region for generating haptic signals. In particular, sound waves can advantageously be emitted in a particularly focused manner in the direction of the holographic image, resulting in particularly good pressure fluctuations and therefore realistic haptic perception. Advantageously, the holographic image can be particularly faithfully related to the pressure fluctuations, for example, in terms of shape, contour, size, etc.

[0126] In another preferred embodiment, the system is characterized in that the one or more sound channels as openings in the substrate are filled with a material, preferably a fluid, particularly preferably water, glycerin, oil, in particular silicone oil, the material preferably having an optical refractive index that substantially corresponds to the refractive index of the substrate.

[0127] Terms such as substantially, approximately, about, and the like preferably refer to a tolerance range of less than ±20%, preferably less than ±10%, particularly preferably less than ±5%, in particular less than ±1%, and always include the exact value. Preferably, similar refers to values ​​that are approximately the same. Part preferably refers to at least 5%, particularly preferably at least 10%, in particular at least 20% or at least 40%.

[0128] Advantageously, by filling the sound channel with a material having a refractive index similar to that of the substrate material, the light rays are refracted less, which eliminates or simplifies subsequent compensation or collimation. The smaller the difference between the refractive index of the material filling the sound channel and the substrate material, the smaller the angular change the light rays undergo, and therefore any collimation that may be performed can be performed without error. Advantageously, this allows the light to be directed without aberrations in the direction of the light exit or light out-coupling region to display a holographic image.

[0129] Oil, preferably optical oil, has been found to be a particularly preferred material for filling the sound channel. In a preferred embodiment, the substrate comprises glass, in particular optical glass or optical plastic, with a refractive index between 1.4 and 1.6, preferably about 1.5. Advantageously, oil, in particular optical oil, can be selected with a similar refractive index between about 1.4 and about 1.6, preferably about 1.5, thus minimizing unwanted refraction effects. Furthermore, oil is characterized by good sound conduction, and therefore sound waves also propagate through the oil-filled sound channel in the direction of the holographic image with little distortion or attenuation.

[0130] In a preferred embodiment, the material filling the one or more sound channels is a fluid having a high surface tension, preferably at least 20 mN / m (millinewtons per meter) at room temperature (20°C), preferably at least 30 mN / m, 40 mN / m, 50 mN / m, 60 mN / m, or more. A high surface tension of the fluid material reduces the risk of the material spilling out of the one or more sound channels. To fill one or more channels, a person skilled in the art can select a material with a preferred surface tension based on known physical laws, depending on the geometry of the sound channel (particularly the cross-section of the sound channel) to ensure that the fluid remains reliably within the sound channel.

[0131] In another preferred embodiment, the system is characterized in that one or more sound channels as openings in the substrate are filled with a material, preferably a fluid, and a membrane or film is present on the substrate formed over at least the region of the one or more filled sound channels. The fluid can preferably be one of the aforementioned preferred fluids having an optical refractive index substantially corresponding to the refractive index of the substrate. Preferably, the fluid can also be air, in which case the membrane or film essentially provides a protection function against contamination.

[0132] Preferably, a film or membrane is formed on both surfaces of the substrate to close off one or more filled sound channels on both sides, which advantageously allows for particularly reliable sealing of the fluid material regardless of the surface tension or geometry of the sound channel.

[0133] Preferably, the film or membrane is transparent to light from the light source. Furthermore, the film or membrane preferably has a refractive index similar to that of the substrate material and / or the material filling the sound channel. Preferably, the membrane or film is impermeable to the trapped fluid material. In preferred embodiments, the film or membrane has a layer thickness of less than 1 mm, preferably 500 μm, 400 μm, 300 μm, 200 μm or less. The membrane or film is preferably vibrable.

[0134] For example, the membrane can be a silicone membrane, and the film can be, for example, a transparent plastic film, such as a PMMA film (polymethyl methacrylate film). The membrane or film can be attached to the substrate surface, at least in the area of ​​the sound channels, by an optical adhesive or an additional OCA film (OCA stands for optically clear adhesive). Preferably, the optical adhesive or OCA film has a similar refractive index to the membrane, film, or substrate material, thereby ensuring a smooth, even composite material. Preferably, the membrane or film confines the fluid in one or more sound channels with few air bubbles. Therefore, there is preferably no air entrapment in the sound channels, which advantageously allows light to pass through the filled sound channels substantially without aberrations.

[0135] In a preferred embodiment, a film lid is applied to the membrane or film. Preferably, the film lid is characterized by having a higher mechanical stability than the film or membrane. For example, it may be preferable for the layer thickness of the film lid to be greater than that of the film or membrane by a factor of 2, 3, 4, 5, 10 or more. For example, the film lid serves to cover and protect the membrane or film. Preferably, the film lid has openings or holes in the area of ​​the sound channels, and the number, shape and size of the openings or holes preferably correspond to the number, shape and size of the sound channels. The film lid can preferably comprise the same material as the substrate, for example optical plastic (e.g., PMMA) or optical glass.

[0136] In a preferred embodiment, the numerous or multiple sound channels contain a material with a refractive index similar to that of the substrate material. In another preferred embodiment, all sound channels are filled with material. In a particularly preferred embodiment, sound channels arranged along or around the light exit or out-coupling region are filled with material. It may also be preferable to fill only sound channels located in the light beam path with a material, preferably a fluid, particularly preferably water, glycerin, oil, preferably silicone oil. In a preferred embodiment, the system is characterized in that one or more sound channels are sealed with a membrane or film. Air or a fluid with a refractive index matched to the refractive index of the substrate, as described above, can be present in the sound channel. Providing a membrane or film advantageously makes it possible to reliably prevent dust from entering the sound channel without impairing sound propagation. Cleaning of the sound channel is not required.

[0137] If no membrane or film is provided to close the sound channel, periodic cleaning of the sound channel may be preferable. To facilitate cleaning of the sound channel, optimization of the shape, particularly the dimensions, of the sound channel may be performed. It may also be preferable for cleaning to be performed by the acoustic transducer itself. For example, one or more acoustic transducers may be designed to generate sound waves that serve to remove dust from the sound channel. In particular, it may be possible to generate sound waves with a sound pressure level that is higher than the average value for providing haptic sensation, preferably by a factor of 1.5, 2, 3, 5, 10, or more.

[0138] Similarly, it may be preferable to apply pulsed sound waves in the sense of "blowing-free" the audio channels in order to remove possible contamination. Therefore, particularly with appropriate configuration in the control unit, one or more acoustic transducers may be designed to emit stronger sound or ultrasound waves within a predetermined time period in order to remove possible contamination from the audio channels. Such cleaning may preferably be performed at regular intervals or depending on the degree of contamination, and it may also be preferable to selectively clean audio channels that are likely to be dirty.

[0139] In another preferred embodiment, the system is characterized in that the substrate comprises one or more holographic optical elements in front of and / or behind the one or more audio channels, which may be configured for optical compensation, deflection, and / or magnification performed on light upon propagation through the one or more audio channels. In this context, in front or behind preferably means upstream or downstream with respect to light propagation within the substrate.

[0140] As a result, advantageously, the light beam can be steered in a targeted manner towards the light output or out-coupling region to generate a holographic image in the interaction region, and / or the path of the beam can be configured to be particularly simple. In a preferred embodiment, the second holographic optical element is located in the light output region or out-coupling region. It may therefore be preferable for the light to be steered towards the second holographic optical element before it is emitted into the interaction region for generating the holographic image.

[0141] The unwanted refractive effect of the sound channel on the light beam can be preferably compensated for by a holographic optical element for compensating the light beam. For example, a compensating HOE can be configured to compensate for the divergence effect of the sound channel by recollimating the light beam. Correction of color effects by ensuring that colors appear correctly using a compensating holographic optical element can also be desirable. In this case, the holographic optical element for compensating light, also called a compensating HOE, can be embedded in front of the sound channel, behind the sound channel, in particular on the front and / or rear surface of the substrate, and / or even within the substrate. The compensating HOE preferably has an inverse optical function for the sound channel, which affects the propagation of the light beam within the substrate and preferably contributes to reducing aberrations.

[0142] In the case of an oval sound channel, the compensation function may for example be in the form of collimation such that the effect of the sound channel is compensated for, ie, offset.

[0143] In a preferred embodiment, the system may also include one or more holographic optical elements configured to deflect the light so that the light beam is steered substantially around the sound channel. In the context of the present invention, these HOEs are called deflecting HOEs. Advantageously, the light beam and the sound channel do not come into contact with each other as a result of the appropriate deflection. In particular, no divergence and / or refraction occurs due to the sound channel in this case, which advantageously results in a faithful holographic image, particularly without distortion.

[0144] In another preferred embodiment, the light can also be fanned out, collimated and manipulated in the direction of the light exit area or the out-coupling area. In the sense of the present invention, expanding the light preferably means increasing the light beam diameter, i.e. the size of the light beam. In particular, the beam diameter relates to the diameter of any line extending perpendicular to the beam axis and cutting it. Advantageously, expanded holographic images can be generated by expanding the light beam. For example, the light beam can be expanded by a holographic optical element that has the effect of a diverging lens, i.e. that emits the light over a large area and in particular deflects the light in the direction of the light exit or the out-coupling area.

[0145] In another embodiment, multiple holographic optical elements can be used to expand the light. In the context of the present invention, this can be called pupil dilation. This term is inspired by the dilation of a person's pupil when a greater amount of light must pass through the iris of the eye, for example, to recognize objects in the dark. In the context of the present invention, pupil dilation means an increase in the size at which light is manipulated into the light exit or out-coupling area.

[0146] In another preferred embodiment, the system is characterized in that the substrate includes an input coupling region and an output coupling region, one or more audio channels at least partially surround the output coupling region, light passing into the output coupling region of the substrate is manipulated to pass through the audio channels by one or more holographic optical elements, and / or light passing into the output coupling region of the substrate is manipulated to pass through the audio channels by the optical channels, and one or more holographic optical elements that expand the light and collimate and manipulate it into the output coupling region are preferably downstream of the audio channels.

[0147] The above-mentioned options for mounting holographic optical elements for light compensation, deflection, and / or magnification can also be used, in particular, when the substrate functions as a light guide. In the context of the present invention, holographic optical elements contributing to the above-mentioned optical functions can be called compensation HOEs, deflection HOEs, or magnification HOEs. In particular, it may be preferable to arrange several such holographic optical elements on and / or in the substrate. In a preferred embodiment, the compensation HOEs, deflection HOEs, or magnification HOEs are selected from the group comprising one or more reflection holograms and / or transmission holograms.

[0148] Furthermore, it is preferred that the substrate connects the optical channels and that the light source illuminates the optical channels and causes the light to enter the substrate via the optical channels. In particular, the light can then be deflected in a targeted manner so that it does not have to propagate through the audio channels but instead propagates around the audio channels. The light is preferably coupled into the optical channels such that total internal reflection always occurs at the interface between the optically dense material (higher refractive index) of the optical channels and the optically less dense material (lower refractive index) surrounding the optical channels.

[0149] Advantageously, the system according to the invention provides many options for manipulating the light, in particular for passing through the audio channel, and propagating said light to the exit or out-coupling region for displaying the holographic image, and in particular ensures that the holographic image does not suffer from aberrations as a result of the geometry of the audio channel, in this case without the need for additional costs (or compensating HOEs).

[0150] In another preferred embodiment, the system is characterized in that the substrate comprises a material which is an optical plastic, preferably selected from the group comprising polymethyl methacrylate (PMMA), polycarbonate (PC), cycloolefin polymer (COP), cycloolefin copolymer (COC), and / or an optical glass, preferably selected from the group comprising borosilicate glass, B270, N-BK7, N-SF2, P-SF68, P-SK57Q1, P-SK58A, and / or P-BK7.

[0151] These materials feature optical properties that are favorable for holography and are suitable for industrial-scale manufacturing. They are advantageously characterized by cost-effective continuous production with consistent, top-notch optical quality. Furthermore, further processing allows for a wide variety of geometrical dimensions and complex geometries.

[0152] In another aspect, the invention relates to the use of a system according to the invention for generating haptic perception and holographic images in an interaction area, which can therefore advantageously be perceived particularly efficiently and optimally from a force sensation point of view, in particular the pressure difference corresponds to the geometric design of the object to be represented by the holographic image, resulting in a particularly realistic impression for the user.

[0153] Those skilled in the art will appreciate that the technical features, definitions, and advantages of the preferred embodiments described for the system according to the present invention for generating haptic perception and holographic images equally apply to the use of the system for generating haptic perception and holographic images, and vice versa.

[0154] In particular, the system according to the invention can be used in many fields of application, in particular in a variety of modern technological applications.

[0155] For example, the system according to the invention can be advantageously used in connection with operating areas, such as holographic buttons. In the sense of the present invention, a holographic button refers to a generated holographic image that can be operated by a user. The user's operation can in particular involve touching. For example, touching can result in the execution of a specific function. For example, it can be envisioned that the system according to the invention displays a keyboard and / or a joystick as a holographic image. In this case, the user can operate, for example, the keyboard and / or the joystick via the holographic image, without having to touch the actual keyboard and / or the joystick in the process. This applies to any object that can be visualized by holographic imaging. This is particularly advantageous from a hygienic point of view, since the object itself does not need to be touched. This is particularly relevant, for example, in the case of devices that are typically used by many users, such as a car gear selector and / or elevator operating buttons.

[0156] In a preferred embodiment, the system includes a detector, which is preferably designed to identify a manipulation gesture relative to the holographic image. The detector is preferably a photodetector for detecting electromagnetic radiation, preferably visible or infrared light. Non-limiting examples include digital image sensors, such as CCD or CMOS sensors, or photodiodes, photocells, or phototransistors, which may preferably be present arranged as an array.

[0157] While the holographic image and haptic perception can be generated in an interaction area in front of the body, the detector preferably allows for detection of manipulation gestures performed within the interaction area. Preferably, a manipulation gesture refers to a user's contactless interaction with the holographic image. For example, if a holographic button or keyboard is generated within the interaction area, the manipulation gesture can be a tap, sweep, or swipe input. For example, in a holographic image in the form of a joystick, the manipulation gesture can similarly correspond to a joystick movement.

[0158] The measurement data obtained by the detector is preferably transmitted to a control or computing unit configured to identify the manipulation gesture, and suitable computer code (software / firmware) for this purpose can preferably be stored and present in the control or computing unit.

[0159] In a preferred embodiment, the system is configured to adjust the display of the holographic image and / or tactile feedback in response to the identified manipulation gesture. For example, it may be preferable to recognize activation of a holographic button either by changing the color and / or shape of the holographic button and / or haptically by pressure variations. Similarly, with respect to a joystick, it may be preferable to update the haptic sensation and / or holographic image of the joystick based on the recognized manipulation gesture.

[0160] As a result, this can provide a particularly easy-to-use manipulation system that allows highly realistic interaction with holographic objects due to contactless manipulation.

[0161] Various arrangements of the detector are possible with regard to positioning, and it is preferred that the detector detects electromagnetic radiation from the interaction region, for which optical components for steering, collimation and / or focusing, such as lenses, mirrors, diffractive structures or holographic optical elements, can be provided.

[0162] In a preferred embodiment, the detector is located behind the body, and thus on the opposite side of the interaction area. In this embodiment, the detector is therefore on the same side of the body as the acoustic transducer. By providing suitable optical components, such as lenses, one or more planes from the interaction area are preferably imaged onto the detector, such as a CCD sensor or CMOS sensor, so that the manipulation gesture can be identified based on the measured data. In this embodiment, the detector is preferably positioned on the optical axis together with the holographic image or the holographic optical element for generating the holographic image.

[0163] To allow any desired positioning of the detector, it may be preferable to provide a second light guide or waveguide which serves to transmit light in the direction of the detector. Preferably, the second waveguide may be a functionalized waveguide as known from WO 2020 / 157306 A1, the contents of which are incorporated herein by reference in their entirety.

[0164] For example, the second waveguide may include a second body having a front surface and a rear surface, the body including a partially transparent second in-coupling region and a second out-coupling region spaced therefrom. Preferably, the second in-coupling region may be positioned on the optical axis with the holographic image and may include a diffractive structure that deflects at least a portion of radiation from a manipulation gesture detected in the interaction region such that the deflected portion propagates within the second body to the second out-coupling region by reflection as in-coupled radiation. The deflected portion of the in-coupled radiation is preferably steered by the second out-coupling region to the detector.

[0165] In this embodiment, the terms second input-coupling region and second output-coupling region refer to regions that input- and output-coupling, respectively, radiation related to a manipulation gesture to be detected from the interaction region. Therefore, the second input-coupling and output-coupling regions can also be referred to as detection input-coupling and detection output-coupling regions in this embodiment. Generally, these regions are not the same as the aforementioned (first) input- and output-coupling regions for generating a holographic image. Similarly, it may be preferable to refer to the second waveguide as a detection waveguide. The embodiments described specifically for a (first) body having a substrate that functions as a light guide preferably equally apply to a second body that serves as a waveguide for radiation to be detected.

[0166] For example, the transparent body can be in the form of a plane-parallel plate. The partially transparent body can be made of glass and / or plastic. It can be one piece or comprise multiple pieces. In particular, the transparent body can transmit radiation or light from the visible wavelength range (preferably 400 nm to 780 nm). Furthermore, it can be transparent to the near infrared (780 nm to 3000 nm, preferably 780 nm to 1400 nm) and / or the entire infrared range (3000 nm to 1 mm, preferably 3000 nm to 50 μm).

[0167] The second in-coupling region can likewise have a transparent or partially transparent configuration. With the desired transparency, the in-coupling of radiation, for example via a diffractive structure, can be very efficient, so that sufficient radiation power is incident on the out-coupling region. A partially transparent second in-coupling region can be implemented such that the in-coupling efficiency is, for example, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50% or more. In this case, the in-coupling efficiency refers to the fraction of radiation detected from the interaction that can be transmitted and thus introduced into the substrate of the second body.

[0168] The transparent or partially transparent second in-coupling region is preferably implemented such that the deflection has no imaging optical function (e.g. has no focusing effect). In particular, the reflection can be total internal reflection at the front and / or rear surface of the transparent body. However, it is also possible to provide a reflective or partially reflective layer or coating for this purpose.

[0169] The out-coupling region of the transparent second body may deflect at least a portion of the in-coupled radiation incident thereon such that the deflected portion exits the second body, preferably via the front or rear surface of the transparent second body towards the detector.

[0170] The second out-coupling region can likewise be partially transparent. In particular, the out-coupling efficiency of the second out-coupling region can be 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50% or more. In particular, the out-coupling efficiency of the second out-coupling region can be in the range of 2% to 50%, and thus the transmittance of the second out-coupling region is in the range of 50% to 98%.

[0171] A partially transparent embodiment is advantageous, for example, when the second in-coupling region and the second out-coupling region are in the form of diffractive structures (e.g., volume holograms). In that case, the second in-coupling region and the second out-coupling region can be in the form of, for example, a film, which is advantageous from a production engineering point of view. However, it is also possible for the second out-coupling region to have maximum out-coupling efficiency. For example, this can be achieved by a reflective coating (preferably a full-surface reflective coating).

[0172] The second in-coupling region and the second out-coupling region can be implemented such that they do not provide any optical imaging function in addition to deflection. However, it is also possible for the second in-coupling region and / or the second out-coupling region to provide an optical imaging function in addition to deflection, and thus perform optical imaging. Thus, the optical imaging function can be, for example, that of a converging or diverging lens, a concave or convex lens, and the curved surface can be a (centered or decentered) spherical or aspherical curved surface.

[0173] In a preferred embodiment, the second out-coupling region also comprises a diffractive structure. The diffractive structure of the second in-coupling region and / or the second out-coupling region can be realized as an embedded diffractive structure, as a diffractive structure between two substrates, or as a diffractive structure embodied on the front or rear surface.

[0174] In particular, a reflective or transmissive hologram can be provided as the diffractive structure for the second in-coupling or out-coupling region. Furthermore, the diffractive structure of the second in-coupling or out-coupling region can also be a transmissive or reflective relief grating. The second out-coupling region can also include mirrors, prisms, and / or reflective or transmissive Fresnel structures. These variations can be provided instead of or in addition to the diffractive structure.

[0175] The second in-coupling region is particularly preferably implemented as a reflection volume hologram with incident angle-dependent wavelength selectivity, which therefore has a high transmission over a wide angle and wavelength range.

[0176] This makes it possible to provide a detector system which allows optical detection of manipulation gestures within the interaction area, advantageously without affecting the quality of the holographic image produced. The second in-coupling area for the detected radiation is preferably arranged on the optical axis with the holographic image in the (first) body or with the holographic element provided therefor, but this does not interfere with the holographic imaging.

[0177] For this purpose, it may be preferable that the wavelength of the radiation to be detected from the manipulation gesture in the interaction area and the wavelength of the radiation from the light source for generating the hologram are different: for example, detection may be performed in the invisible wavelength range (e.g., in the infrared range), while the holographic image is generated in the visible range.

[0178] The diffractive structures or holographic elements in the (first) body (for generating the holographic image) or in the second body (for detecting the manipulation gesture) can preferably be designed for different wavelengths, for example, a reflective volume hologram in the second body can be designed to reflect infrared radiation for the radiation to be detected from the interaction area and transmit light for generating the holographic image in the visible range.

[0179] In a preferred embodiment, the system combined with the detector comprises an IR radiation source (infrared radiation source), which is preferably designed to provide IR radiation to the interaction area. In particular, IR radiation relates to infrared radiation in the range of 780 nm to 1 μm, preferably 780 nm to 50 μm. Particularly preferably, the infrared radiation emitted by the IR radiation source is radiation in the near-infrared range (780 nm to 3 μm, preferably 780 nm to 1400 nm).

[0180] In addition to a second waveguide for guiding the radiation to be detected from the interaction area to the detector, the (first) body preferably serves to generate a holographic image, or its substrate also serves as a light guide, preferably as a guide for light in the visible wavelength range.

[0181] The second body for detecting the manipulation gesture can preferably be a separate component from the (first) body for generating the holographic image. For example, the second body for detection can be located in front of or behind the (first) body that provides beam guidance for the holographic image. In this case, it may be preferable for the first and second bodies to be located apart from each other. Similarly, the first and second bodies may be interconnected to achieve a multi-layer structure. Preferably, the (first) body guides radiation from the light source (e.g., in the visible range) to generate the holographic image, while the second body guides radiation (e.g., also in the visible range or infrared range) from the interaction area to the detector for detecting the manipulation gesture.

[0182] Advantageously, in these embodiments, both the detector (for detecting the manipulation gesture) and the light source (for generating the holographic image) can be flexibly and advantageously positioned depending on the available installation space: corresponding first and second in-coupling or out-coupling regions can easily be provided in the first or second body for this purpose.

[0183] The two bodies themselves can form a compact unit, behind which the acoustic transducer is arranged as mentioned above. The embodiment is characterized by a particularly compact configuration. In particular, the installation depth of the system can be very shallow, so that in this direction it requires very little installation space. The system is easy to install and offers a wide range of application options.

[0184] To ensure a subsequent reliable haptic perception within the interaction area, it is preferable that the second body for detecting manipulation gestures also have audio channels, which are preferably arranged so as to be congruent with the audio channels arranged in the substrate of the first body for generating the holographic image. As will be appreciated by those skilled in the art, the preferred embodiments described above with respect to the configuration of audio channels in the substrate of the (first) body equally apply to providing audio channels in the second body (or its substrate) that serve to guide the beam for detecting manipulation gestures.

[0185] In another embodiment, it may be preferable for the first and second bodies to form a unit, i.e., preferably designed as a (single) body that serves both as a waveguide for radiation for generating a holographic image and as a waveguide for radiation for detecting a manipulation gesture. In other words, it may be preferable to provide only a (first) body having a (preferably monolithic) substrate, within which both radiation for generating a holographic image and radiation for detecting a manipulation gesture are guided, as described above. Consequently, such a body preferably includes both a first input-coupling and output-coupling region for radiation for generating a holographic image and a second input-coupling and output-coupling region for radiation for detecting a manipulation gesture from the interaction region. Advantageously, the first and second input-coupling and output-coupling regions can be positioned independently of each other within the body, depending on the requirements for positioning the light source (for generating a hologram) or the detector (for detecting a manipulation gesture). Rather than providing two bodies or waveguides, it is advantageous for the body for generating a hologram to simultaneously serve as a detection waveguide. Firstly, this allows for a particularly compact configuration, which advantageously allows for the integration of a system with a very shallow installation depth, and secondly, this embodiment avoids an interface between the two bodies, which allows for a particularly high quality to be continuously obtained in terms of the detection of the holographic image and the operating gestures.

[0186] In a preferred embodiment of the system, a plurality of input-coupling portions can be provided in the second body for detecting manipulation gestures, said input-coupling portions steering radiation of the manipulation gesture to be detected from the interaction area to a plurality of assigned output-coupling portions. Thus, the second input-coupling area and the second output-coupling area preferably comprise the same number of input-coupling portions and output-coupling portions, respectively, which can be arranged, for example, in a line or in a matrix. Preferably, a sensor portion of a detector can be assigned to each output-coupling portion.

[0187] Preferably, the detector is configured to continuously measure the intensity of radiation incident on each input coupling portion and provide it to the controller. Preferably, the controller is configured to determine the distance of the input means (e.g., a hand) of the manipulation gesture in front of the respective input coupling portion based on the measured intensity. Ambient light can be used for detection. A decrease in the measured intensity of the input coupling portion indicates that a shadow has been cast on the input coupling portion due to the proximity of the input means (e.g., a finger of a hand). Similarly, active illumination of the input means within the interaction area, for example, by a separate light source (e.g., by an LED frame), is also possible. Such configurations of preferred functionalized waveguides are disclosed, for example, in WO 2022 / 022904 A1, the contents of which are incorporated herein by reference in their entirety.

[0188] In WO 2022 / 022904 A1, a functionalized waveguide is used to provide a contactless area sensor, particularly intended to enable contactless input in a selected area in front of an optoelectronic display, such as an LCD or OLED element. According to the present invention, the aforementioned detection principle for contactless determination of the distance of an object in front of an optoelectronic display can also be used to identify manipulation gestures in the interaction area. For example, for this purpose, an array of input coupling sections can be provided, preferably on the second body, with the input coupling sections covering the dimensions of the interaction area. By determining the intensity with a suitable detector array, it is possible to detect the distance of an input means (e.g., a hand) from the first or second body. Advantageously, by providing an array, e.g., a matrix, of input coupling sections, the distance of the input means in different areas in front of the first or second body can also be simultaneously detected. A preferably identified two-dimensional distance surface allows conclusions to be drawn regarding the performed manipulation gesture.

[0189] In a preferred embodiment, the input coupling portions are adaptable to the holographic image being generated. For example, if a holographic keyboard is being generated, the input coupling portions may preferably correspond to the individual holographic keys. Pressing of a holographic key can preferably be determined based on a decrease in the intensity of the corresponding input coupling portion. This embodiment therefore allows for a simple and reliable detection of user interactions with operating elements represented by a holographic image.

[0190] The system according to the invention will now be described in more detail with reference to non-limiting examples. [Brief explanation of the drawings]

[0191] [Figure 1a-b] 1 shows a diagram of edge-lit in-coupling of light via a first holographic optical element. [Figure 2] A schematic diagram of the sound field is shown. [Figure 3a-b] 10 shows a view of the audio channel around the second holographic optical element in plan and side views. [Figure 4] 10 shows in plan view a view of the sound channels all around the second holographic optical element. [Figure 5] 1 shows a diagram of a system according to the invention in plan view. [Figure 6a-b] 1 shows a diagram of the effect of different cross sections of the audio channel on the path of the beam of light. [Figure 7a-b] 1 shows an illustration of the effect of the compensation HOE. [Figure 8a-b] 1 shows a diagram of the compensation HOE arrangement. [Figure 9a-b] 1 shows a view of the audio channel as a gap in plan and side view. [Figure 10a-b] 1 shows a diagram of a tilted sound channel and tilted acoustic transducer arrangement. [Figure 11] 1 shows a diagram of the path of a beam through a tilted audio channel. [Figure 12]1 shows a diagram of a system according to the invention with an optical channel and an enlarged HOE. [Figure 13] 1 shows a diagram of a system according to the present invention in combination with a magnification HOE with pupil dilation. [Figure 14] 1 shows diagrams of possible configurations of deflection HOEs. [Figure 15a-b] 1 shows a diagram of a sound channel filled with material. [Figure 16] 1 shows a diagram of multiple compensation HOEs. DETAILED DESCRIPTION OF THE INVENTION

[0192] Detailed Description of the Drawings FIG. 1 shows a schematic diagram of various options for emitting and / or coupling light into a substrate 5 .

[0193] FIG. 1a illustrates an embodiment in which light enters the substrate via an edge-lit geometry. In this case, light from a light source 7 is emitted toward the substrate 5. For example, the light source 7 can be an LED. In particular, the light can enter the substrate 5 laterally and be in-coupled through a side, i.e., enter the substrate from an edge. Within the substrate, the light can propagate toward a second holographic optical element 15, which is used to generate a holographic image 3 in a desired area, i.e., the user can perceive the holographic image 3 optically (visually) and by force or touch. In particular, the second holographic optical element 15 can be configured as an out-coupling hologram, so that the holographic image 3 appears to float freely within the interaction area.

[0194] 1b shows an embodiment in which light enters the substrate 5 by a first holographic optical element 13. As a result of the first holographic optical element 13, light of a specific wavelength (and therefore a specific color) and at a specific angle of incidence can be coupled into the substrate 5 and directionally deflected according to a received function. In particular, the light can be directionally steered in the direction of the second holographic optical element 15 to generate a holographic image 3 within the interaction area.

[0195] FIG. 2 shows a schematic diagram of a sound field that can be generated by the emission of sound waves by an acoustic transducer (not shown here). Depending on the arrangement of the audio channels (not shown here), interference phenomena can result in sound pressure and / or sound pressure patterns for haptic perception. In particularly close areas, constructive interference can result in particularly strong haptic signals being perceived, while in far areas, outgoing sound waves cause destructive interference, weakening the haptic signal so that it cannot be felt by the user once it leaves the interaction area. Preferably, the pressure field can be increased in a predetermined manner, which depends on the power of the acoustic transducer, the arrangement of the audio channels, and / or their geometric configuration. For example, it is possible to obtain a sound field increase of up to about three times between different spatial portions within the interaction area.

[0196] The configuration of different pressure variations within the interaction area can generate a particularly realistic haptic perception of the holographic image 3. For example, the holographic image 3 can represent an object such as a joystick. With the system 1 according to the present invention, the area of ​​the joystick that is to be grasped can have a higher pressure than the area that represents the contour. The haptic perception allows the user to get the impression that he or she is grasping an object, e.g., a joystick, in his or her hand. Preferably, the acoustic transducer can use beamforming of sound waves to generate particularly directionally focused, and therefore intense, sound waves in specific areas of the interaction area.

[0197] FIG. 3 shows in plan and side view the arrangement of the audio channels surrounding the out-coupling region containing the second holographic optical element 15.

[0198] 3a shows a plan view of one embodiment of a system 1 according to the present invention. In this case, the audio channel 11 partially surrounds the out-coupling region including the second holographic optical element 15. The audio channel is not located in the region from which the light ray or beam emitted by the light source 7 propagates in the direction of the second holographic optical element 15 (indicated by the arrow in the figure). As a result, the light is not unnecessarily deflected, for example as a result of a lensing effect that may be caused by the audio channel 11. Instead, the light can advantageously propagate uninterrupted in the direction of the holographic optical element 15, generating the holographic image 3 in the interaction region. The audio channel 11 is formed as an opening in the substrate 5.

[0199] Figure 3b shows a side view of this embodiment. As is evident from the side view, the substrate 5 is positioned between the acoustic transducer 9 and the interaction area. Acoustic waves propagate through the audio channel 11 in the direction of the holographic image 3, further generating a haptic signal for the user within the interaction area due to pressure variations.

[0200] 4 shows a plan view of sound channel 11 completely surrounding the output coupling region including second holographic optical element 15. In this embodiment of system 1 according to the invention, sound channel 11 is arranged as an aperture around the entire periphery of second holographic optical element 15, and sound waves pass through said aperture to generate a particularly focused and / or broad-area haptic signal.

[0201] 5 shows a plan view of another embodiment of a system according to the invention. A light source 7 emits light towards a substrate 5. The figure shows that the light is deflected while propagating through an audio channel 11. This is because the substrate material and the medium within the audio channel 11 may have different refractive indices. An acoustic transducer 9 is behind the substrate 5, and emitted sound waves (indicated by the circle around the acoustic transducer 9) pass through the audio channel 11.

[0202] In particular, ultrasound can be emitted by an acoustic transducer. When ultrasound is used, tactile or haptic sensations for the user are triggered by sound pressure fluctuations within the interaction area. In this case, ultrasound has been found to be particularly advantageous for generating particularly realistic haptic perceptions for the user.

[0203] The light propagates in the direction of the second holographic optical element 15, so that the holographic image 3 can appear in front of the exit or out-coupling area of ​​the substrate 5. Thus, the system 1 according to the present invention allows for the generation of both the holographic image 3 and haptic sensations, and the substrate 5 does not block or obstruct sound.

[0204] FIG. 6 shows the effect that different geometric cross sections of the sound channel have on the propagation of light within the substrate 5.

[0205] 6a shows the influence of a polygonal cross section on the propagation of light. It is clear that an undeflected or only slightly deflected light beam can be obtained by an audio channel having a polygonal cross section, in particular a quadrilateral cross section. For this purpose, the boundaries of the audio channel 11 are preferably oriented perpendicular to the propagation direction of the light beam. This is advantageous for the design of the optical unit of the system 1 according to the invention, since the path of the light can be particularly easily controlled, for example by installing optical components and / or holographic optical elements. As a result, a polygonal cross section, in particular a quadrilateral cross section, of the audio channel 11 is particularly suitable for obtaining an efficient and simple path of the beam.

[0206] Figure 6b shows the effect on light propagation of an elliptical cross-section of the sound channel 11. The elliptical cross-section of the sound channel 11 is advantageous for the propagation of sound waves, since the modal spectrum changes little or not at all with the elliptical shape.

[0207] However, when passing through an audio channel 11 having an elliptical cross section (a circular cross section is shown), the light beam may lose its collimation and be refracted outward. Therefore, the elliptical cross section may have an effect similar to that of a diverging lens. As explained in more detail below, various compensation options can be provided to recollimate the light beam.

[0208] FIG. 7 shows the effect of the compensating HOE 17 of the preferred embodiment.

[0209] In Figure 7a, a compensation HOE 17 is present and is arranged so that the light passes through it after passing through the audio channel 11. As a result, the light can be collimated, for example, if the audio channel has the effect of a diverging lens.

[0210] 7b shows another option for compensating for unwanted effects that the audio channel 11 may have on light propagation. In the illustrated embodiment, the compensation HOE 17 is positioned so that light first passes through it and then through the audio channel 11. The compensation HOE 17 can be configured to pre-compensate for the refractive effects of the audio channel, for example by the compensation HOE 17 having an optical function. The compensation HOE 17 is preferably designed so that it can accept different incident light angles and correctly blend different wavelengths, avoiding chromatic aberrations in the propagation of light within the substrate.

[0211] Figure 8 shows another possible arrangement of the compensating HOE 17. In Figure 8a the compensating HOE 17 is embedded in the substrate 5, while in Figure 8b the substrate is on the surface of the substrate 5. For example, the compensating HOE 17 can be connected by being laminated to the substrate 5, for example in the form of a film, and / or bonded with an adhesive.

[0212] Concomitantly, the illustrated options for connecting to the substrate 5 apply equally to all holographic optical elements in the figures. Preferably, the holographic optical elements can be applied on and / or in the substrate 5.

[0213] 9 shows a view of the sound channel 11 as a gap in plan and side view. A polygonal, and in particular a quadrilateral, cross section of the sound channel 11 has been found to be particularly advantageous for the path of the beams, as this reduces the complexity of the path of the beams.

[0214] 9a shows in plan view a number of audio channels 11 arranged to surround an out-coupling region containing a second holographic optical element 15, the audio channels 11 being formed as gaps. The audio channels 11 in the form of gaps are arranged such that light first passes through the gaps and then propagates to the second holographic element 15 to generate the holographic image 3.

[0215] Figure 9b shows the same arrangement as that of Figure 9a in side view.

[0216] FIG. 10 shows an embodiment of the system 1 according to the invention in which the sound channel 11 and / or the acoustic transducer 9 are present at an angle.

[0217] 10a shows that audio channel 11 is tilted. As a result, sound waves propagating through audio channel 11 exhibit different diffraction behavior than when audio channel 11 is not tilted. In this case, tilted audio channel 11 is characterized by a tilt angle. Advantageously, this can increase sound pressure at specific locations within the interaction area, resulting in a more pronounced haptic signal.

[0218] 10b shows an embodiment of the system 1 according to the invention in which the sound channel 11 and the acoustic transducer 9 are present at an angle. It turns out advantageously here that the pressure variations perceptible by sound pressure and haptics can be increased up to a certain range.

[0219] FIG. 11 shows another embodiment of the system 1 according to the invention in which the beam paths and the sound channels 11 are tilted.

[0220] 11a shows the beam path of a light ray propagating through an inclined sound channel. Here, it is clear that the light is refracted in the sound channel 11 because the substrate material and the material located within the sound channel 11 have different refractive indices. Therefore, the system 1 according to the present invention should preferably be designed such that the refractive effects of the sound channel are compensated for or the light is guided through the sound channel.

[0221] 11b shows an embodiment in which some but not all of the sound channels 11 are tilted, resulting in a consistently higher sound pressure in the interaction area, which advantageously results in a stronger haptic perception of the holographic image 3.

[0222] FIG. 12 shows an embodiment of the system 1 according to the present invention, in which the magnifying HOE 21 is arranged. Furthermore, the system 1 according to the present invention includes a light channel 23. A light source emits light in the direction of the light channel 23. Advantageously, the light channel 23 is connected to the substrate 5, where the light is steered in a targeted manner through the audio channel 11. As a result, the light is advantageously not refracted and therefore does not need to be compensated for. Instead, the light channel 23 continues to guide the light to the magnifying HOE 21. The magnifying HOE 21 expands the light, particularly with respect to the propagation area. As a result, the light is steered over a wide area, preferably collimated, towards the second holographic optical element 15 to display the holographic image 3.

[0223] 13 shows an embodiment of the system 1 according to the invention, which includes an expansion HOE 21. In this case, multiple holographic optical elements are arranged side by side to obtain pupil dilation. Light from the light source 7 is very narrowly coupled into the substrate 5, deflected, and propagates around the sound channel 11, causing pupil dilation by the expansion HOE 21 in the form of multiple holographic optical elements. In this process, the light is also expanded, and the light is preferably expanded and collimated and guided by the multiple holographic optical elements to a second holographic element.

[0224] FIG. 14 shows another option for steering the light through the sound channel 11 in a targeted manner. This is particularly advantageous for embodiments in which the sound channel has an elliptical cross section, since the light can then be reflected outward. In this process, an additional polarizing HOE 19 is utilized to steer the light through the sound channel 11 in a targeted manner, in particular by total internal reflection. The light then reaches the second holographic optical element 15, which generates the holographic image 3. The polarizing HOE 19 can here be in the form of a transmission and / or reflection hologram. In particular, multiple light sources 7, in particular two light sources 7, can also be used.

[0225] FIG. 15a shows an embodiment in which several sound channels 11 are filled with a material. Preferably, the material has a refractive index similar to that of the substrate material. Advantageously, the smaller the difference in refractive index between the substrate material and the material used to fill the sound channels 11, the smaller the reflection effects or angular changes that the light undergoes on its path to the second holographic optical element 15 to ultimately generate the holographic image 3. Oil has proven particularly advantageous as a filling material for the sound channels 11, since oils, especially optical oils, can be tailored to be particularly close to the preferred optical glass or plastic, while at the same time being selected to have a refractive index that registers good sound transmission. Materials such as glycerin, water, and / or silicone oil can also be advantageously used to fill the sound channels 11.

[0226] FIG. 15b shows a schematic cross-section of a portion of the substrate 5 (indicated by a dashed line) that includes the sound channel 11 filled with a material, preferably a fluid. A film or membrane 25 is formed along the sound channel 11 to surround the material (indicated by black fill). Preferably, the film or membrane 25 is formed on both sides of the surface of the substrate 5 to close the filled sound channel 11. Preferably, the film or membrane 25 is transparent to light from the light source and opaque to the enclosed material, preferably a fluid. For example, the membrane can be a silicone membrane, and the film can be, for example, a transparent plastic film, such as a PMMA film (polymethyl methacrylate film), present in the sound channel area and formed on the substrate surface by an optical adhesive or OCA film (not shown here). It may be preferable to form a film lid 27 on the film or membrane 25 to cover and protect the film or membrane 25. In the area of ​​the sound channel 11, the film lid 27 has an opening 29, which in terms of shape and size corresponds to the shape and size of the sound channel 11 (cross-section). Preferably, the film lid material 27 may be made of the same material as the substrate 5 .

[0227] 16 shows an embodiment of the system according to the invention in which multiple compensation HOEs 17 are arranged. In this case, each compensation HOE 17 is arranged in front of and behind the circular sound channel 11. Advantageously, this can facilitate light compensation, since the light is focused by the compensation HOE 17 in front of the sound channel 11, causing the light rays to be perpendicularly incident on the boundary when entering and exiting the sound channel. This makes it possible to particularly efficiently avoid unwanted refraction effects and imaging aberrations. [Explanation of symbols]

[0228] 1 System 2. Input coupling region 3. Holographic Images 4 Output Coupling Area 5. Substrate 7 light source 9 Acoustic Transducers 11 audio channels 13 First holographic optical element 15 Second Holographic Optical Element 17 Compensation HOE 19 Deflection HOE 21 Enlarged HOE 23 optical channels 25 Film or membrane 27 Film lid material 29 Opening in film lid

Claims

1. A system (1) for generating haptic perception and holographic images (3) in an interaction area, comprising: a. a light source (7) that emits light; b. a body comprising a substrate (5) and at least one holographic optical element (13, 15, 17, 19, 21, 23), said light source (7) and said body being designed to generate a holographic image (3) within said interaction area; c) one or more acoustic transducers (9) that emit sound waves in the direction of said interaction area so that pressure variations are haptically perceptible within said interaction area (3); Including, The system (1) is characterized in that the substrate (5) is arranged between the one or more acoustic transducers (9) and the interaction area, the substrate (5) includes one or more sound channels (11), and the sound waves propagate at least partially through the one or more sound channels (11) in the direction of the holographic image (3).

2. characterised in that it is designed to generate the holographic image (3) by means of a transmission and / or reflection hologram, A system (1) according to claim 1.

3. the substrate comprises an in-coupling region (2) and an out-coupling region (4) at different positions on the substrate, the light propagating in the substrate (5) between the in-coupling region (2) and the out-coupling region (4) by reflection, preferably total internal reflection, A system (1) according to claim 1.

4. the in-coupling area (2) is arranged on the periphery of the substrate (5) and / or the in-coupling area (2) comprises a first holographic optical element (13), the light being in-coupled into the substrate (5) and deflectable within the substrate (5) by the first holographic optical element (13), A system (1) according to claim 3.

5. the out-coupling area (4) comprises a second holographic optical element (15), and light for generating the holographic image (3) in the interaction area exits through the out-coupling area (4), A system (1) according to claim 3.

6. 2, 3, 5, 10, 20, 50, 100 or more acoustic transducers (9), said acoustic transducers (9) preferably arranged in an array. A system (1) according to claim 1.

7. characterised in that the acoustic transducer (9) is an ultrasonic transducer adapted for sound emission in the frequency range of 20 kHz to 100 kHz, preferably 30 kHz to 60 kHz; A system (1) according to claim 1.

8. The pressure fluctuations are generated by acoustic sound waves having a carrier frequency and a modulation frequency, the carrier frequency being preferably 20 to 100 kHz and / or the modulation frequency being in the range of 0.1 Hz to 500 Hz, particularly preferably in the range of 150 Hz to 250 Hz. A system (1) according to claim 1.

9. the light source (7) is arranged inside or outside the substrate (5), the light source (7) being preferably a laser and / or an LED; A system (1) according to claim 1.

10. the one or more sound channels (11) are formed as openings in the substrate (5), A system (1) according to claim 1.

11. characterised in that the one or more sound channels (11) have an elliptical and / or quadrilateral cross section, A system (1) according to claim 1.

12. characterised in that the one or more sound channels (11) have an inclination angle in the substrate, thereby making it possible to focus the sound waves on the holographic image (3), A system (1) according to claim 1.

13. the one or more sound channels (11) partially or completely surround an outlet or out-coupling area (4) in the substrate (5), A system (1) according to claim 1.

14. 2. The system (1) according to claim 1, characterized in that one or more sound channels (11) are filled as openings in the substrate (5) with a material, preferably a fluid, particularly preferably water, glycerin, oil, preferably silicone oil, said material having a refractive index that substantially corresponds to the refractive index of the substrate.

15. one or more sound channels (11) are present as openings in the substrate (5) filled with a material, preferably a fluid, and a membrane or film (25) is present formed on the substrate (5) over the area of ​​at least one of the filled sound channels or a plurality of the filled sound channels (11), A system (1) according to claim 1.

16. characterised in that the substrate (5) comprises one or more holographic optical elements in front of and / or behind one or more sound channels (11) configured for compensation (17), deflection (19) and / or magnification (21) of the light that the light experiences by propagation in the one or more sound channels (11), A system (1) according to claim 1.

17. the substrate (5) comprises an in-coupling region (2) and an out-coupling region (4), the one or more audio channels (11) at least partially surrounding the out-coupling region (4), the light passing to the out-coupling region (4) of the substrate (5) is steered through the audio channels by one or more holographic optical elements (19) and / or the light passing to the out-coupling region (4) of the substrate (5) is guided through the audio channel (11) by an optical channel (23), and one or more holographic optical elements (21) are preferably downstream of the audio channels, expanding the light and steering it in a collimated state to the out-coupling region, A system (1) according to claim 1.

18. characterised in that the substrate (5) comprises a material which is an optical plastic, preferably selected from the group comprising polymethyl methacrylate (PMMA), polycarbonate (PC), cycloolefin polymer (COP), cycloolefin copolymer (COC), and / or an optical glass, preferably selected from the group comprising borosilicate glass, B270, N-BK7, N-SF2, P-SF68, P-SK57Q1, P-SK58A and / or P-BK7, A system (1) according to claim 1.

19. Preferably, the device comprises a detector designed to identify a manipulation gesture relating to the holographic image. A system (1) according to claim 1.

20. Use of the system (1) according to claim 1 for generating haptic perceptions and holographic images (3) within an interaction area.

Images