Patent Application
20220400236
The present application claims the benefit under 35 U.S.C. § 119 of German Patent Application No. DE 10 2021 206 073.0 filed on Jun. 15, 2021, which is expressly incorporated herein by reference in its entirety.
Data glasses such as, for example, “Google Glasses,” are described in the related art. One conventional display method for such data glasses is the so-called retinal scan display described in U.S. Patent Application Publication No. US 2015/0362734 A1, which may include holographic optical elements (HOE) as imaging elements.
The present invention is directed to an optical system for a virtual retinal scan display. In accordance with an example embodiment of the present invention, the optical system includes at least one projector unit including a modulatable light source for generating at least one modulated light beam and including one movable deflection device for the at least one light beam, a scanning projection of an image content being generatable from that at least one light beam as a result of the movement of the movable deflection device, and at least one diverting unit, onto which the image content is projectable and which is configured to map the projected image content into an exit pupil and to guide it onto an eye of a user.
In accordance with an example embodiment of the present invention, it is provided that the optical system includes an optical exit pupil shifting unit situated in an optical path of the light beam for the manual or at least semi-automated spatial shifting of the exit pupil, and in particular, of an eye box of the optical system, preferably in directions which extend at least essentially in parallel to an exit pupil plane of the exit pupil. This may enable an advantageous spatial adjustability of an exit pupil position and/or of an eye box position. A viewing experience may advantageously be significantly improved. It may be advantageously ensured that an image remains visible even with a shifting of the data glasses or with an eye movement of the user. A simple adaptation to different user physiognomies (“one size fits all”) may be advantageously achieved. A particularly large effective total eye box may be advantageously achieved. An “effective total eye box” is understood to mean a spatial range of pupil positions of a user eye, in which the entire image content from at least one exit pupil of the virtual retinal scan display (RSD) is able to reach through the pupil of the user eye.
A “virtual retinal display” may be understood to mean a retinal scan display or a light field display, in which the image content may be scanned sequentially by the deflection of at least one light beam, in particular, of a laser beam of at least one temporally modulated light source such as, for example, one or multiple laser diodes, and is mapped by optical elements directly onto the retina of the user eye. The modulation of the light source takes place, in particular, on the basis of an image data output of an image source. The image source is designed, in particular, as an electronic image source, for example, as a graphic output, in particular, a (integrated) graphic map, of a computer or processor or the like. The image source may, for example, be integrally designed with a, for example, image processing unit of the optical system that dynamically modifies the output image data. Alternatively, the image source may be designed separately from the image processing unit and may convey the image data to the image processing unit of the optical system. The image data are designed, in particular, as color image data, for example, RGB image data. The image data may be designed, in particular, as still images or as moving images, for example, as videos. The image data are designed, in particular, for the purpose of enabling a representation of an image content to be mapped. The image processing unit is provided preferably for the purpose of modifying, in particular, distorting, copying, skewing, off-setting, scaling or the like the image data of the image source. The image processing unit is designed preferably for the purpose of generating copies of the image content, which are, in particular, modified, for example, distorted, skewed, offset and/or scaled.
In accordance with an example embodiment of the present invention, the projector unit is configured, in particular, to radiate the image content from the image data in the form of scanned and/or rasterized light beams. The projector unit includes, in particular, the movable deflection device. The movable deflection device may be designed as a MEMS mirror (micro-mirror actuator), in particular, at least for the controlled deflection of the at least one light beam of the light source of the projector unit. The MEMS mirror in this case may be movable/pivotable in two dimensions. Alternatively, the MEMS mirror may also be formed from two successively connected 1-D mirrors. Alternatively or in addition, the deflection device includes at least one connectable diffractive optical element in the form of a phase modulator and/or intensity modulator, which may be designed, for example, as a spatial light modulator (SLM) with a reflective design, for example, with a DMD or LCoS design, or with a transmissive design, for example, as an LCD. The temporally modulatable light source, in particular, is analog-modulated, an alternative TTL modulation, for example, also not being ruled out, however. The diverting unit includes, in particular, an arrangement of optical elements, for example, diffractive, reflective, refractive and/or holographic optical elements. However, the diverting unit preferably always includes at least one holographic optical element. The diverting unit is preferably at least partially integrally formed in at least one lens of data glasses. It is also possible, of course, that each lens of the data glasses includes a holographic optical element. The diverting lens is provided, in particular, for the purpose of diverting merely a portion of the intensity of the projected image content onto the user eye. At least one further portion of the intensity of the projected image content passes through the diverting unit. The diverting unit appears essentially transparent to a user, as viewed at least from a perpendicular viewing direction. The diverting unit forms, in particular, a projection area. The projection area forms, in particular, an area within which a light beam, when it strikes the diverting unit, is deflected/diverted in the direction of the user eye, in particular, in the direction of an eye pupil area of the optical system.
An “eye pupil” (Ramsden circle) is understood to mean, in particular, an image-side image of a (virtual) aperture diaphragm of the optical components of the optical system generating the image of the image content. In one intended use of the optical system, in particular, at least one of the exit pupils of the optical system overlaps with an entrance pupil of the user eye. The image content (or the respective mapping of the image content) situated preferably in a (virtual) entrance pupil of the optical components of the optical system is, in particular, mapped in the exit pupil. The exit pupil of the optical system forms, in particular, at least one part of an eye box. A diameter of the exit pupil is, in particular, smaller than an average diameter, preferably smaller than a minimum diameter of the entrance pupil of the user eye. An “eye box” in this case is understood to mean a spatial area within which all light beams of the scanning projection are able to pass the entrance pupil of the user eye. The spatial position of the exit pupil may be changed with the aid of the exit pupil shifting unit manually, for example, via a switch, adjusting dial or the like, or in an automated manner, for example, with the aid of an automatically controlled solenoid actuator or the like. The exit pupil plane may extend at least essentially in parallel with a lens of the data glasses. The optical exit pupil shifting unit includes, in particular, at least one optical element or a combination of multiple optical elements. The individual or combined optical elements may each be designed as diffractive optical elements and/or as reflective optical elements and/or as refractive elements, which act in particular, in an optically focusing and/or optically deflecting manner. It is possible that the spatial displacement of the exit pupil position is achieved by a spatial shift of at least one sub-component, in particular, of at least one optical element of the optical exit pupil shifting unit and/or by a manipulation of intrinsic optical characteristics of at least one sub-component, in particular, of at least one optical element of the optical exit pupil shifting unit such as, for example, a change of a refraction angle, of a refraction index, of a reflection angle, etc., for example, controlled by a mechanical change of shape or by applying an electrical signal such as a voltage.
In accordance with an example embodiment of the present invention, it is further provided that the optical exit pupil shifting unit is situated in the optical path of the light beam between the light source and the movable deflection device. An advantageous implementation of an optical system shifting the exit pupil position may be enabled as a result. A particularly space-saving implementation of the optical exit pupil shifting unit may be advantageously achieved, in particular, since the light beam in front of the deflection device still has a particularly small cross section. With a more compact design of the optical exit pupil shifting unit, it is advantageously possible to achieve a lower weight and with an automated activation, a lower energy consumption. It is possible, in particular, that a MEMS control or an actuator system identical to a MEMS control may be used for a manipulation/movement of at least one optical element of the exit pupil shifting unit. In addition, a higher resolution may be advantageously achieved in this case, since a shift/distortion of the projected image content on the retina may be kept particularly small in this case. It is possible that at least the light source, the optical exit pupil shifting unit and the movable deflection device are housed in a shared projector housing.
It is also provided that the optical exit pupil shifting unit is designed as an, in particular, single focal lens. In this way, advantageous characteristics with respect to the shift of the spatial position of the exit pupil may be achieved. A compact and, in particular, structurally uncomplicated (optionally currentless) implementation of the exit pupil shifting unit may be advantageously enabled. The focal lens is provided, in particular, for the purpose of spatially shifting a point of incidence of the light beam exiting the light source on the movable deflection unit. This shift is implemented by the optical system in a spatial shift of the point of incidence of the projected light beam scanned with the aid of the movable deflection unit on the diverting unit and thus in the spatial shift of the exit pupil position. A focal lens acts on the light beam, in particular, in a focusing manner. A slightly acentric striking of the light beam on the focal lens also results, in addition to the focusing, in a smaller deflection of the light beam from a straight beam direction.
In this context, it is provided that the focal lens is displaceably mounted for generating the spatial shift of the exit pupil in at least one plane, which is extended at least essentially perpendicularly to a propagation direction of the light beam in an area of the optical system situated (directly) in front of the focal lens. In this way, the spatial shift of the point of incidence of the light beam on the movable deflection device and the related advantageous effects with respect to a shift of the exit pupil may be advantageously achieved. The expression “essentially perpendicularly” is intended here to define, in particular, an orientation of a direction relative to a reference direction, the direction and the reference direction, viewed, in particular, in a projection plane, encompassing an angle of 90°, and the angle having a maximum deviation, in particular, of less than 8°, advantageously less than 5° and particularly advantageously less than 2°. An area situated in front of the lens is understood, in particular, to mean an area of the optical system situated in the beam direction of the light beam in front of the focal lens/an area of the optical system situated upstream of the beam relative to the focal lens.
In accordance with an example embodiment of the present invention, it is also provided that the focal lens is displaceably mounted for focusing the image content mapped in the exit pupil at least in a direction that extends at least essentially in parallel to a propagation direction of the light beam in the area of the optical system (directly) in front of the focal lens. In this way, an additional, in particular, particularly simple and space-saving and cost-saving focusing option may be advantageously created. This may also advantageously compensate for a slight defocusing produced by a shift of the focal lens perpendicularly to the propagation direction of the light beam. This may advantageously enable a sharpness of the projected image content to be corrected. In addition, an actuator system, which is already used for shifting the exit pupil position, may also be advantageously used for correcting the sharpness. A high degree of compactness may be achieved as a result.
Alternatively or in addition, it is provided that the optical exit pupil shifting unit is situated in the optical path of the light beam between the movable deflection device and the diverting unit. A preferably small aperture of the projector unit and/or a small spatial extension of the deflection direction, in particular, of the MEMS mirror (small MEMS aperture) may be advantageously achieved. In this way, costs, in particular, for the MEMS system may be advantageously held to a minimum. The optical exit pupil shifting unit situated in such a way is situated, in particular, within a close range of a beam outlet of the projector unit or within the projector unit, for example, within the shared projector housing. A close range in this context is understood to mean, in particular, an area formed by points, whose points are all less than 2 cm, preferably less than 1 cm, and preferably less than 0.5 cm away from the beam outlet of the projector unit. The beam outlet is designed, in particular, as an opening in the projector housing. The exit pupil shifting unit situated between the movable deflection device and the diverting unit forms, in particular, a part of the projection optical system and/or of an objective lens of the projector unit.
In accordance with an example embodiment of the present invention, it is additionally provided that the optical exit pupil shifting unit is designed as a multi-lens lens system including at least one first lens and including at least one second lens, the second lens being situated in the optical path of the light beam downstream from the first lens and, in particular, in parallel to the first lens. This may advantageously enable a simple design of a mechanically manipulatable optical exit pupil shifting unit. The lenses each have, in particular, focal lengths in the lower centimeter range. The multi-lens lens system has a focal length, in particular, of a few centimeters, for example in a range between 5 cm and 25 cm, in particular, 15 cm. The lenses are each designed, in particular, as thin lenses.
A simple and effective spatial shift of the exit pupil may be advantageously achieved if, in order to produce the spatial shift of the exit pupil, the first lens of the multi-lens system is displaceably mounted at least in a plane extending at least essentially in parallel to a main extension plane of the first lens. A “main extension plane” of an element is understood to mean a plane, which extends in parallel to a largest lateral surface of a smallest possible cuboid, which only just completely encloses the element and, in particular, runs through the midpoint of the cuboid. A distance between the two lenses remains, in particular, at least essentially the same in the case of a lateral shift of the first lens. The second lens remains, in particular, at least essentially immobile during the shift of the first lens. The first lens is, in particular, (laterally) displaceably mounted relative to the second lens.
In accordance with an example embodiment of the present invention, it is further provided that the optical exit pupil shifting unit is designed as a phased array optical system, in particular, as a phased array optical element. An optical exit pupil shifting unit unaffected by mechanical position changes and/or of mechanical actuators may thereby be advantageously. A compact design may be advantageously enabled as a result. The phased array optical system is provided, in particular, for the purpose of manipulating a deflection, preferably a deflection angle, of the light beam as a function of an electrical signal (current/voltage) applied to the phased array optical system. With the aid of the technology of the phased array optical system, it is possible to guide the direction of light beams that exit the phased array optical element by dynamically controlling optical characteristics of a surface on a microscopic scale. The phased array optical element may be designed, in particular, as an optical phased array transmitter, which may replace or form, in particular, the light source of the projector unit and, optionally, also the movable deflection device of the projector unit. The optical phased array transmitter includes, in particular, a light source (laser), a power splitter, a phase shifter and an array of radiator elements. The output light of the laser source in the phased array transmitter, in particular, is divided into multiple branches using a power splitter tree in such a way that each branch is fed to an adjustable phase shifter. The light phase-shifted in this way is then fed to a radiating element (for example, to a nanophotonic antenna), which couples the light into the open space. The light radiated by the elements is combined in the far-field and forms the far-field pattern of the phased array optical element. By adjusting the relative phase shift between the elements, it is possible to form and guide the light beam.
In accordance with an example embodiment of the present invention, it is also provided that the optical system includes an image processing unit for, in particular, dynamically generating and outputting image data defining the image content to the projector unit, the image processing unit being provided for the purpose of adapting a distortion and/or a spatial size of the image data as a function of an instantaneous setting of the optical exit pupil shifting unit, in particular, by a change of a resolution, in such a way that when a setting of the optical exit pupil shifting unit is changed, the user perceives an essentially unchanged image content. A particularly advantageous visual impression may be advantageously achieved as a result, the perceptible images remaining free of cropped edges or the like. An unchanged image content may, in particular, be shifted, expanded, compressed, etc. as a result of the spatial shift of the exit pupil, so that after an adjustment, the image content potentially strikes a changed (for example, smaller or larger) surface of the retina. The image processing unit is provided, for example, for the purpose of shifting an image line near the edge further in the direction of an image center of a maximum possible image output area by reducing a resolution, in order to prevent a change of the image area near the edge in the perception of the user. In this way, all further image lines situated further inward must also be shifted, which is achievable by a reduction of the total resolution. The image processing unit is provided, in particular, for dynamically adapting the image data based on an eye-tracking of the user eye. That the image content “remains essentially the same” is understood to mean, in particular, that the image content is free of cropped (edge) areas.
In accordance with an example embodiment of the present invention, it is additionally provided that the optical system includes an eye-tracking unit, which is provided for the purpose of detecting at least one eye movement of the eye of the user, a control unit of the optical system being configured, based on the eye movement data of the eye of the user detected by the eye-tracking unit, to dynamically adapt a setting of the optical exit pupil shifting unit in such a way that the exit pupil remains in superposition with an entrance pupil of the eye of the user. As a result, a viewing experience may be advantageously significantly improved. The effective total eye box may be significantly enlarged as a result. The eye-tracking unit may also be provided for detecting and/or determining a rate of eye movement, a pupil position, a pupil size, a viewing direction, an accommodation state and/or a fixation distance of the eye. The eye-tracking unit is designed, in particular, as one component of the virtual retinal scan display, in particular, of the optical system. Detailed designs of eye trackers are described in the related art, so that no further discussion thereof will follow at this point. It is possible that the eye tracker unit includes a monocular or a binocular eye-tracking system. The eye tracker unit is preferably integrated at least partially in a component of the data glasses, for example, in a frame of the data glasses. The eye-tracking unit includes, in particular, a control unit, which is provided for the purpose of converting eye movement data detected by the eye-tracking unit into control commands for the exit pupil shifting unit, in particular, for actuators of the exit pupil shifting unit, which move the focal lens or the first lens of the multi-lens lens system. The control unit of the eye-tracking unit is provided, in particular, for controlling actuators of the exit pupil shifting unit. A “control unit” is understood to mean, in particular, a unit that includes at least control electronics. “Control electronics” are understood to mean, in particular, a unit including a processor unit, in particular, a processor and including a memory unit, in particular, a memory chip or the like, and including an operating program stored in the memory unit and executable by the processor unit.
In accordance with an example embodiment of the present invention, data glasses including the optical system and a method for projecting image contents onto the retina of a user with the aid of the optical system are also provided, the exit pupil and, in particular, an eye box of the optical system being spatially shifted manually or in an at least semi-automated manner by an optical exit pupil shifting unit situated in an optical path of the light beam, preferably in directions which extend at least essentially in parallel to an exit pupil plane of the exit pupil. This may enable an advantageous spatial adjustability of an exit pupil position and/or of an eye box position. A viewing experience may be advantageously significantly improved. This may advantageously result in an image remaining visible even with a shifting of the data glasses or with an eye movement of the user.
The optical system according to the present invention, the data glasses according to the present invention and the method according to the present invention are not to be limited to the application and specific embodiment described above. The optical system according to the present invention, the data glasses according to the present invention, and the method according to the present invention may, in particular, include a number differing from a number of individual elements, components and units as well as method steps cited herein for fulfilling an operating principle. In addition, in the case of the value ranges indicated in this description, values also lying within the aforementioned limits are to be considered as described and as arbitrarily useable.
Further advantages result from the description of the figures below. Four exemplary embodiments of the present invention are represented in the figures. The figures and the description contain numerous features in combination. Those skilled in the art will purposely also view the features individually and combine them to form meaningful further combinations, in view of the disclosure herein.
Optical system 30a forms a virtual retinal scan display (cf. the highly simplified representation in
Optical system 30a includes a diverting unit 18a. The image content is projected onto diverting unit 18a. Diverting unit 18a is integrated into one of the eyeglass lenses 70a, 72a. Diverting unit 18a is static. Diverting unit 18a is configured to map the projected image content into an exit pupil 20a of optical system 30a, in particular, into an exit pupil 20a formed by optical system 30a. Diverting unit 18a is configured to guide (deflect) light beams 14a in the direction of eye 22a of the user. For the image content to be able to be successfully projected onto retina 68a of eye 22a of the user, exit pupil 20a must overlap with an entrance pupil 64a of eye 22a of the user. Optical system 30a includes an eye-tracking unit 60a. Eye-tracking unit 60a is provided for the purpose of detecting an eye movement of eye 22a of the user. Control unit 62a of optical system 30a is configured, based on the eye movement data of eye 22a of the user detected by eye-tracking unit 60a, to dynamically adapt a setting of an optical exit pupil shifting unit 26a (cf.
Optical exit pupil shifting unit 26a is situated in optical path 24a of light beam 14a. Optical exit pupil shifting unit 26a represented in the exemplary embodiment of
Focal lens 38a is also displaceably mounted in a further direction 44a, which extends in parallel to propagation direction 42a of light beam 14a in front of focal lens 38a. The shift of focal lens 38a in further direction 44a serves to focus the image content mapped in exit pupil 20a. The shift of focal lens 38a in further direction 44a serves to compensate for/to offset the slight defocusing generated by the shift of focal lens 38a in plane 40a (see also
Three further exemplary embodiments of the present invention are shown in
As a result of the shift of exit pupil 20b, a change of an image projected on a retina 68b of eye 22b of the user may also be generated. An effect occurring as a result is schematically represented in
It is noted that a meaningful combination of the exemplary embodiment including multi-lens lens system 46b and of the exemplary embodiment including focal lens 38a is possible.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 206 073.0 | Jun 2021 | DE | national |
