Spectacle lens for a display device which can be placed on the head of a user and which generates an image, and display device comprising such a spectacle lens

Abstract

The invention relates to a spectacle lens for a display device (1) which can be placed on the head of a user and which generates an image, wherein the spectacle lens (3) has a front face (23) and a rear face (11), an entry portion (28) and a deflection portion (18) spaced apart from the entry portion (28), and a light-guiding channel (21), wherein the spectacle lens (3) has a channel shell (13) in which the light-guiding channel (21) runs, and has a first lens (24; 25), wherein the light-guiding channel (21) guides light beams (L1) of the generated image, which are coupled into the spectacle lens (3) via the entry portion (28), up to the deflection portion (18), from which they are deflected in order to exit the spectacle lens (3) via the rear face (11), wherein the first lens (24; 25) comprises a first stack composed of a first plastic shell (30; 32) and a first reinforcement shell (31; 33), wherein the first reinforcement shell (31; 33) has a higher bending rigidity than the first plastic shell (30; 32).

Description

[0001] patent attorneys

[0002] GEYER, FEH NERS & PARTNER

[0003] Munich - Jena tooz technologies GmbH

[0004] Attorney's file: PAT 4377 / 070-PCT

[0005] Spectacle lens for a display device that can be placed on a user's head and produces an image, and display device with such a spectacle lens

[0006] The present invention relates to a spectacle lens having the features of the preamble of claim 1 and a display device with such a spectacle lens.

[0007] Such a spectacle lens can have two lenses (a push lens and a pull lens) and a waveguide located between them. When the lens is used as intended, the pull lens is closer to the user's eye than the push lens. Since collimated light with a focal plane at infinity is generally used to transport the generated image in the waveguide, the pull lens typically has a negative refractive power to shift the focus of the virtual image towards near vision. If farsightedness correction is required, the pull lens may have a positive refractive power. For viewing the surroundings, the influence of the pull lens is at least partially compensated by the positive refractive power of the push lens. The push-lens-waveguide-pull-lens arrangement is also referred to as the ARx stack.

[0008] The push and pull lenses serve two purposes: firstly, to "pull" the augmented image (or the virtually displayed image) from infinity to a finite distance from the user, and secondly, to implement visual correction for the user. For an immersive experience, a large field of view (FoV > 50°) of the augmented image is required. The field of view for a high-refractive-index waveguide is maximized when the adjacent medium is air (the medium with the lowest refractive index in the visible spectral range, n=1). Therefore, an air gap is used between the waveguide and the adjacent optical components (push and pull lenses).

[0009] The air gap must also be maintained even under external stress on the spectacle lens. For example, the push and pull lenses must not touch the waveguide under pressure, as this would disrupt the total internal resection of the waveguide and / or damage the waveguide, which can also disrupt the total internal resection. Pressure forces occur when cleaning the lens surfaces and are tested in the ophthalmological environment according to ISO 14889 (static pressure test) or FDA - 21 CFR 801 .410.

[0010] GEYER, FEH NERS & PARTNER

[0011] Munich - Jena

[0012] The ARx stack was tested for medical approval using the 2-ball drop test. To maintain the air gap, it must be sufficiently large, the lenses sufficiently thick, or the entire push-pull stack protected from pressure within a housing. Each of these approaches results in a large form factor (high overall thickness and weight of the ARx stack), which contradicts the current trend in HMD product development.

[0013] Lightweight spectacle lenses made of polymer materials (thiourethanes, episulfides, Mitsui Resin (MR-8, MR-7, MR-10, MR-174), polycarbonate (PC), polyallyldiglycol carbonate (CR-39), and polyamide) represent the state of the art in ophthalmology. The elastic modulus of the polymers used is approximately 20 times lower than that of mineral glass (~80 GPa), so their flexural stiffness is reduced by the same factor. Flexural stiffness determines the thickness of a spectacle lens or the size of the air gap between the lens and the waveguide to prevent contact under pressure.

[0014] For such spectacle lenses, form factor and weight are critical factors, as they are used in a display device worn on a user's head when used as intended.

[0015] Based on this, the object of the invention is to provide a spectacle lens of the type mentioned above in which the form factor and / or weight can be reduced. Furthermore, a display device with such a spectacle lens and a method for manufacturing such a spectacle lens are to be provided.

[0016] The invention is defined in independent claims 1 and 18. Advantageous embodiments are specified in dependent claims.

[0017] A spectacle lens is provided for a display device that can be placed on a user's head and generates an image. The spectacle lens has a front and a back, an entry section and a deflection section spaced apart from the entry section, as well as a light-guiding channel. The spectacle lens further comprises a channel shell in which the light-guiding channel runs, and a first lens. The light-guiding channel directs light beams of the generated image, which are coupled into the spectacle lens via the entry section, to the deflection section, from which they are deflected to exit the spectacle lens via the back. The first lens has a first lens side facing the channel shell and a second lens side facing away from the channel shell, and the channel shell has a first channel side facing the first lens. The first lens has an imaging effect (e.g.,for refractive error correction) and wherein the first lens side and the first canal side are spaced apart from each other in such a way that patent attorneys.

[0018] GEYER, FEH NERS & PARTNER

[0019] Munich - Jena

[0020] 3. A first air gap exists between them to allow total internal reflection of the light beams guided in the light channel at the first channel side. The first lens has a first stack consisting of a first plastic shell and a first reinforcing shell, the first reinforcing shell having a higher bending stiffness than the first plastic shell.

[0021] According to the invention, a small form factor (low overall thickness and low weight) of the spectacle lens can be achieved while simultaneously correcting vision using the spectacle lens.

[0022] The channel shell is isolated from the first lens by the air gap. If a second lens is provided, the channel shell is preferably isolated from the second lens by a further air gap. Here, "air gap" specifically means that only a gaseous material is present between the channel shell and the first or second lens. This material can be air or a gas.

[0023] Due to the reinforcing shell with its higher flexural stiffness compared to the plastic shell, a reduction in the thickness of the first lens can be achieved. The invention thus enables the use of a very thin first lens (and / or a very thin second lens) in combination with an air gap.

[0024] The first plastic shell can be connected to the first reinforcing shell. This can be achieved, for example, using an adhesive and / or a clamping element (e.g., at the edge of the shells). Alternatively, the first plastic shell can be formed or molded onto the first reinforcing shell, e.g., by casting.

[0025] The first lens surface is preferably planar and / or the first channel surface is preferably planar. The air gap can (but need not) have a constant thickness along the light-guiding channel. In particular, the planar first lens surface and the planar first channel surface can be parallel to each other.

[0026] However, it is also possible that the first lens side and / or the first canal side are curved.

[0027] The first plastic shell can be made of a polymer material (e.g., thiourethane, episulfide, Mitsui Resin (MR-8, MR-7, MR-10, MR-174), polycarbonate (PC), polyallyldiglycol carbonate (CR-39), and polyamide). The first reinforcing shell can be made of, for example, glass (e.g., mineral glass material), a transparent ceramic, or a nanoparticle-reinforced composite, and / or one or more diamond layers. Patent attorneys

[0028] GEYER, FEH NERS & PARTNER

[0029] Munich - Jena

[0030] 4. In particular, the material forming the reinforcement shell has a higher modulus of elasticity than the polymer material of the plastic shell.

[0031] This allows the effective elastic modulus of the first lens, and thus the bending stiffness of the first lens, to be increased, while at the same time maintaining the optical properties such as transparency.

[0032] The bending stiffness is preferably chosen to be large enough to maintain the air gap under pressure. In particular, the air gap should always be larger than twice the wavelength of visible light (approx. 400-800 nm) to prevent the virtual image from the waveguide being coupled into the lens via an evanescent field.

[0033] The following scenarios can be preferably taken into account when designing the first lens so that the air gap can always be maintained:

[0034] Gripping / pressing of the outer surfaces during cleaning etc. (forces <10 N, see Lee et al., Science 370, 2020, 966-970 and DIN ISO 9211-4), static loads of up to 100 N according to DIN EN ISO 14889 and / or high-frequency impact loads according to FDA ball drop test, 21 CFR 801.410.

[0035] Preferably, the refractive index of the reinforcing shell can be matched to the refractive index of the plastic shell.

[0036] The bending stiffness can be characterized by the product of the modulus of elasticity and the area moment of inertia, where the modulus of elasticity of the first reinforcing layer is at least ten times the modulus of elasticity of the first plastic layer. Furthermore, the modulus of elasticity of the first reinforcing layer can be x times the modulus of elasticity of the first plastic layer, where x can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 50, 100, or higher (e.g., up to 1000). For diamond, with the theoretically highest modulus of elasticity of approximately 1000 GPa, the difference compared to the plastic materials (modulus of elasticity 1–5 GPa) can be approximately three orders of magnitude (a factor x of 1000).

[0037] The first plastic shell and / or the first reinforcing shell can / may produce the imaging effect of the first lens.

[0038] Both the first plastic shell and the first reinforcing shell in the first stack can extend to a circumferential edge of the first lens. In other words, the first plastic shell and the first reinforcing shell are flush with the circumferential edge of the patent holders.

[0039] GEYER, FEH NERS & PARTNER

[0040] Munich - Jena

[0041] 5. Form the first lens. Additionally or alternatively, neither the first plastic shell extends laterally over the first reinforcing shell, nor does the first reinforcing shell extend laterally over the first plastic shell.

[0042] The spectacle lens may have a first frame (e.g. a first clamping unit) that clamps the first stack (or the first lens) all the way around.

[0043] The first version or the first clamping unit can additionally seal the first air gap in a gas- and moisture-tight manner.

[0044] The first lens can be refractive and / or diffractive. Additionally or alternatively, the first lens can be a Fresnel lens.

[0045] The first plastic shell and the first reinforcement shell can be arranged in the first stack such that the first reinforcement shell is closer to the channel shell than the first plastic shell.

[0046] Furthermore, the reinforcing shell and the plastic shell can be bonded with an adhesive having the same refractive index. Therefore, the interfaces have no optical effect.

[0047] The difference between the refractive index of the first plastic shell for a first wavelength of 550 nm and the refractive index of the first reinforcing shell for the first wavelength can be less than or equal to 0.2.

[0048] The difference between the refractive index of the first plastic shell for the first wavelength and the refractive index of the adhesive for the first wavelength can be less than or equal to 0.1 (preferably less than 0.01 and most preferably less than 0.001).

[0049] Alternatively or additionally, surfaces forming the interfaces can have an anti-reflective coating to reduce reflections due to refractive index differences of the components.

[0050] Additionally or alternatively, the reinforcement shell and the plastic shell can be bonded with a removable adhesive.

[0051] Preferably, the connection between the reinforcing shell and the plastic shell is reversible and / or detachable, so that the plastic shell can be replaced and / or renewed. If the patent attorneys

[0052] GEYER, FEH NERS & PARTNER

[0053] Munich - Jena

[0054] 6. Since the plastic shell provides (or contributes to) refractive error correction, it is easy to adapt to a changing refractive error of the user.

[0055] The surfaces of the first lens that border air can be coated with an anti-reflective coating.

[0056] The side of the first lens facing away from the channel shell may be provided with a hard layer, a hard coating or a hardcoat.

[0057] The plastic shell alone or the first lens as a whole can be designed as a refractive spectacle lens or as a refractive and diffractive Fresnel lens.

[0058] The reinforcing shell can be integrated into the design of the first lens, giving it not only a purely mechanical but also an optical function. This approach can further reduce the thickness of the first lens.

[0059] The reinforcement shell can consist of a laminate made of several layers of different materials.

[0060] The first lens preferably has a first mount that connects the reinforcing shell to the plastic shell and / or the first lens to the canal shell. The first mount can be designed to prevent rotation of the reinforcing shell relative to the plastic shell and / or rotation of the first lens relative to the canal shell. Preferably, the first mount clamps the reinforcing shell to the plastic shell circumferentially. This increases the bending stiffness compared to a resting position of the first lens on the canal shell without clamping (loose bearing).

[0061] The first lens holder or clamp can also be designed to athermize the first lens. Athermizing the first lens in this context means, in particular, that the optical properties of the first lens are (as far as possible) insensitive to changes in ambient temperature, or that the optical properties of the first lens do not change, or only change slightly, when the ambient temperature changes.

[0062] The first version, or the surrounding clamp, can be used to hermetically seal the air gap to prevent contamination, condensation, and similar issues. Patent attorneys

[0063] GEYER, FEH NERS & PARTNER

[0064] Munich - Jena

[0065] 7

[0066] The spectacle lens can have a second lens, which has a third lens face facing the channel shell and a fourth lens face away from the channel shell. The channel shell also has a second channel face facing the second lens, and the second lens can have an imaging function. The third lens face and the second channel face can be spaced apart from each other such that a second air gap exists between them to allow total internal reflection of the light beams guided in the light channel at the second channel face. The second lens can have a second stack consisting of a second plastic shell and a second reinforcing shell, the second reinforcing shell having a higher bending stiffness than the second plastic shell.

[0067] The second lens can be formed in the same way as the first lens and may be further developed.

[0068] For example, both the second plastic shell and the second reinforcing shell in the second stack can extend to a peripheral edge of the second lens. In other words, the second plastic shell and the second reinforcing shell are flush with the peripheral edge of the second lens. Neither the second plastic shell nor the second reinforcing shell extends laterally beyond the second plastic shell.

[0069] The second plastic shell can be connected to the second reinforcing shell. This can be achieved, for example, using a second adhesive and / or a clamping unit (e.g., at the edge of the shells). Alternatively, the second plastic shell can be formed or molded onto the second reinforcing shell, e.g., by casting.

[0070] The spectacle lens according to the invention makes it possible to provide display devices (e.g. HMDs) that can be placed on a user's head and generate an image, with smaller form factors and large viewing angles due to the air gap.

[0071] The spectacle lens can have an exit point on its back surface through which the deflected light beams exit the lens. Furthermore, the deflecting section can redirect the light beams, which have been guided up to it, towards the exit point in such a way that they exit the lens through the exit point and are thus coupled out of the lens.

[0072] The deflection section and the exit section can be spatially separated sections. However, it is also possible for the deflection section and the exit section to coincide spatially, e.g., if the deflection section is designed as a surface lattice. Patent attorneys

[0073] GEYER, FEH NERS & PARTNER

[0074] Munich - Jena

[0075] 8

[0076] In the first spectacle lens, the deflection section can have a single reflective or semi-reflective deflection element or several reflective and / or semi-reflective deflection elements arranged side by side. With several reflective or semi-reflective deflection elements arranged side by side, a desired deflection function and, if necessary, a certain imaging function of the deflection section can be achieved, for example, in a Fresnel-like manner (this can, of course, also be achieved with a single reflective or semi-reflective deflection element). The reflective or semi-reflective deflection elements can be reflective or semi-reflective surface sections, which can also be referred to as reflective or semi-reflective facets. The reflective or semi-reflective surface sections can each be planar. However, it is also possible that the reflective or semi-reflective surfaces can be...The partially reflective surface sections themselves are curved (for example, spherically or aspherically curved, or freeform). Similarly, the single reflective or partially reflective deflecting element can be flat or curved (for example, spherically or aspherically curved, or freeform).

[0077] Additionally or alternatively, the deflection section can have at least one holographic element, at least one volume holographic element and / or at least one diffractive element.

[0078] The reflectivity of the respective reflective deflection elements (or the single reflective deflection element) can, for example, range from 2% to 100% (including the limits of this range). Thus, the reflective deflection elements can be partially reflective or fully reflective.

[0079] The spectacle lens according to the invention can in particular have a curved back surface and / or a curved front surface. The entry section can be formed in the back surface and / or in the channel shell.

[0080] The back and / or the front can have a spherical curvature, an aspherical curvature, a toric curvature and / or a freeform curvature.

[0081] If only the back surface is curved, the front surface is flat. Conversely, if only the front surface is curved, the back surface is flat.

[0082] The light beams of the image-generating module are preferably guided through one or more total internal reflections to the deflection section. Patent attorneys

[0083] GEYER, FEH NERS & PARTNER

[0084] Munich - Jena

[0085] 9

[0086] A display device is provided comprising a holding device that can be placed on the user's head, an image generation module attached to the holding device which generates an image, and a spectacle lens according to the invention (including all further developments) attached to the holding device, wherein the generated image is coupled into the first shell via the entry section, guided in the first shell by at least reflection to the deflection section and deflected at the first deflection section in order to exit the spectacle lens via the inner shell, so that the user can perceive it as a virtual image in the state of the holding device being placed on the head.

[0087] The display device can include a control unit that controls the image generation module. In particular, the control unit can control the image generation module based on supplied image data.

[0088] The image generation module and / or an image sensor unit of the image generation module may, in particular, comprise a planar image sensor, such as an LCD module, an LCoS module, an OLED module, a pLED, or a tilting mirror matrix. Each image sensor may have a plurality of pixels, which may be arranged, for example, in rows and columns. Each image sensor may, for example, be self-illuminating or non-self-illuminating.

[0089] Each image sensor can preferentially produce a monochromatic image, while different image sensors can produce monochromatic images with different wavelengths.

[0090] The image generation module can, for example, comprise a polychromatic image source, a combination of two or more monochromatic image sources, or a combination of a duochromatic and a monochromatic image source. Typical configurations of such image generation modules with multiple image sources include a superposition unit that combines the light beams of the multiple image sources into a single, common light beam. Such a superposition unit can be implemented, for example, as a beam splitter cube (also called an X-cube) or as a so-called rod combiner, both of which are known to those skilled in the art.

[0091] The image generation module can produce the image with a first lateral chromatic aberration that (partially or completely) compensates for a second lateral chromatic aberration caused by the spectacle lens in the virtual image.

[0092] Since the decoupling deflection section should be as invisible as possible and should also impair the light coming from the surroundings to the viewer's eye as little as possible, patent attorneys

[0093] GEYER, FEH NERS & PARTNER

[0094] Munich - Jena

[0095] 10. Generally, deflection sections are preferred that exhibit high transmission in transparent light and, consequently, low reflectivity for the light beam(s) of the at least two-color image to be extracted. Typical reflectivity values ​​are, for example, 50%, 30%, 10%, or 2%, uniformly across the visible wavelength range.

[0096] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations given, but also in other combinations or on their own, without leaving the scope of the present invention.

[0097] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying drawings, which also disclose essential features of the invention. These exemplary embodiments serve only for illustration and are not to be interpreted as limiting. For example, a description of an exemplary embodiment with a plurality of elements or components is not to be interpreted as meaning that all of these elements or components are necessary for implementation. Rather, other exemplary embodiments may also contain alternative elements and components, fewer elements or components, or additional elements or components. Elements or components of different exemplary embodiments may be combined with one another unless otherwise specified. Modifications and variations described for one of the exemplary embodiments may also be applicable to other exemplary embodiments.To avoid repetition, identical or corresponding elements in different figures are designated with the same reference symbols and are not explained multiple times. The figures show:

[0098] Fig. 1 is a schematic perspective representation of an embodiment of the display device according to the invention;

[0099] Fig. 2 shows an enlarged partial sectional view of the first spectacle lens including a schematic representation of the first image generation module according to Fig. 1;

[0100] Fig. 3 is an enlarged partial sectional view of the first spectacle lens according to Fig. 1; Fig. 4 is an enlarged partial sectional view of a conventional spectacle lens;

[0101] Fig. 5 is a diagram showing the thickness and mass of the outer lens of the conventional lens.

[0102] The spectacle lens 24' of Fig. 4 is shown as a function of the air gap thickness g;

[0103] Fig. 6A is a diagram showing the thickness of the outer lens 24 with a plastic shell 30, which has a thickness of 0.5 mm, as a function of the air gap thickness g;

[0104] Fig. 6B is a diagram showing the thickness of the outer lens 24 with a plastic shell 30 having a thickness of 1.0 mm as a function of the air gap thickness g; Patent Attorneys

[0105] GEYER, FEH NERS & PARTNER

[0106] Munich - Jena

[0107] 11 Fig. 6C shows a diagram in which the thickness of the outer lens 24 with a plastic shell 30, which has a thickness of 1.5 mm, is shown as a function of the air gap thickness g;

[0108] Fig. 7A is a diagram showing the mass of the outer lens 24 with a plastic shell 30 having a thickness of 0.5 mm as a function of the air gap thickness g;

[0109] Fig. 7B is a diagram showing the mass of the outer lens 24 with a plastic shell 30 having a thickness of 1.0 mm as a function of the air gap thickness g, and

[0110] Fig. 7C is a diagram showing the mass of the outer lens 24 with a plastic shell 30 having a thickness of 1.5 mm as a function of the air gap thickness g;

[0111] In the embodiment shown in Fig. 1, the display device 1 according to the invention comprises a holding device 2 that can be placed on the user's head, which can, for example, be designed in the manner of a conventional eyeglass frame, as well as a first and a second lens 3, 4, which are attached to the holding device 2. The first lens 3 and / or the second lens 4 can each be designed as a lens according to the invention. The holding device 2 with the lenses 3, 4 can, for example, be designed as sports glasses, sunglasses, and / or glasses for correcting a visual impairment, wherein a virtual image can be projected into the user's field of vision via the first lens 3, which can also be referred to as a multifunctional lens, as described below.

[0112] The display device 1 includes an image generation module 5, which can be arranged in the area of ​​the right temple of the holding device 2, as shown schematically in Fig. 1.

[0113] The image generation module 5 can include an image sensor unit 7 for generating a first image, as schematically illustrated in Fig. 2. For this purpose, the image sensor unit 7 comprises a planar image generation element 8, to which an image sensor optic 9 is arranged. However, it is also possible that the image sensor optic 9 is not provided and can therefore be omitted. The planar image generation element 8 can, for example, comprise an OLED element, an LCD element, an LCoS element, a pLED, or a tilting mirror matrix, each comprising a plurality of pixels arranged, for example, in rows and columns. A single light beam L1 is shown schematically as a representative of the light beams emitted by the planar image generation element 8.

[0114] As can be further seen in Fig. 2, a control unit 10 with, for example, a processor P and a memory M is provided for controlling the image generation module 5. The control unit 10, which can, for example, be arranged on the holding device 2, controls in patent attorneys

[0115] GEYER, FEH NERS & PARTNER

[0116] Munich - Jena

[0117] 12. Depending on the supplied image data, the image generation module 5, and in particular the image generation element 8, is activated such that the first image is generated according to the image data. The light beams L1 emitted by the image generation element 8 pass through the image transmitter optics 9 and then enter the first spectacle lens 3. The area of ​​entry can also be referred to as the entry surface 12.

[0118] The first spectacle lens 3 is multi-layered and comprises a channel shell 13, an outer shell 24 (hereinafter also referred to as outer lens 24), and an inner shell 25 (hereinafter also referred to as inner lens 25). The channel shell 13 is the middle shell located between the outer shell 24 and the inner shell 25. The shells 13, 24, and 25 are connected in such a way that an air gap 26 exists between the channel shell 13 and the outer shell 24, and an air gap 27 exists between the channel shell 13 and the inner shell 25, so that the light L1 is guided in the channel shell 13 by total internal reflection. For this purpose, a frame 40 can be provided, for example, which connects the outer lens 24 to the channel shell 13 in such a way that the air gap 26 is sealed gas- and moisture-tight from the environment.Furthermore, a socket 41 can be provided which connects the inner lens 25 to the channel shell 13 in such a way that the air gap 27 is sealed gas- and moisture-tight from the environment.

[0119] In the embodiment described here, the channel shell 13 is designed as a plane-parallel plate, except for the area of ​​the entrance surface 12. The inner shell 25 is designed as a lens 25 with negative refractive power, and the outer shell 24 is designed as a lens with positive refractive power. The side of the outer shell 24 facing away from the channel shell 13 forms the front 23 of the first spectacle lens 3, and the side of the inner shell 25 facing away from the channel shell 13 forms the back 11 of the first spectacle lens 3.

[0120] Due to the air gaps 26, 27, the light beams L1 are only reflected if their angle of incidence is 0 EWith respect to the surface perpendicular F (shown as a dashed line in Fig. 2) of a surface element where total internal reflection is to take place, the corresponding critical angle 0 is larger. G For angles of incidence in the range from 0° to the critical angle 0 G The canal shell 13 is transmissive, so that the user can perceive the surroundings with his eye A through the first lens 3, as indicated by the arrow U in Fig. 2.

[0121] These transmission and reflection properties are predominantly present for radiation in the visible wavelength range. Patent attorneys

[0122] GEYER, FEH NERS & PARTNER

[0123] Munich - Jena

[0124] 13 Furthermore, the channel shell 13 has a buried deflection section 18 which includes one (or more, not shown in Fig. 2) partially reflective deflection element 19, which can also be referred to as a partially reflective facet 19.

[0125] As previously described, the light beams L1 enter the first lens 3 via the entrance surface 12. The entrance surface 12 is formed on a lateral entrance section 28 of the channel shell 13, which, in the embodiment described here, projects laterally beyond the outer and inner shells 24, 25. In addition to the entrance surface 12, the lateral entrance section 28 has a (here, planar) deflecting surface 29, which deflects the light beams L1 in a first direction (here, the y-direction) towards the deflecting section 18 such that the light beams L1 are guided by total internal reflection at the interfaces of the channel shell 13 to the corresponding air gap 26, 27 and up to the deflecting section 18. The deflecting surface 29 can be, for example, reflective or partially reflective. It is also possible to design the deflecting surface 29 to be diffractive. In this case, the deflection surface can (but does not have to) also be parallel to channel side 36 or 39, or a part of channel side 36 (e.g.The channel side 39 can be a reflective grating or a reflective hologram, or a transmissive grating or a transmissive hologram, so that the inclined side for the deflection surface 29 does not need to be provided. The channel shell 13 can, for example, be designed as a plane-parallel plate.

[0126] The deflecting section 18 then deflects the light beams L1 such that the deflected light beams L1 exit the first lens 3 via the inner lens 25 and thus via the back surface 11, creating a virtual image that the user can perceive with their eye A. The area through which the light beams L1 exit can also be referred to as the exit section 22 or exit surface 22.

[0127] Thus, in the channel shell 13 there is a light guidance channel 21 which extends along the first direction from the entry section 12 to the deflection section 18.

[0128] Since collimated light L1 with a focal plane at infinity is generally used to transport the generated image in the channel shell 13 (which can also be called a waveguide), the inner lens 25 typically has a negative refractive power to pull the focus of the virtual image towards the near range for the user (e.g., 0.5 m - 2 m). Therefore, the inner lens 25 can also be called a pull lens 25. For correcting the refractive error of highly hyperopic spectacle wearers, it may be necessary for the inner lens 25 to have a positive refractive power.

[0129] For viewing the surroundings, the influence of the pull lens 25 is compensated by the outer lens 24 with positive refractive power. Therefore, the outer lens 24 can also be called a push lens 24. Patent attorneys

[0130] GEYER, FEH NERS & PARTNER

[0131] Munich - Jena

[0132] The outer lens 24 can be designated as 14. It is optional that the outer lens 24 can be omitted. The outer shell 24 can be omitted, for example, if the focus position of the virtual image is not adjusted. In that case, the pull lens 25 is preferably only required for refractive error correction.

[0133] In addition to adjusting the focus plane of the virtual image, the Pull lens 25 can be used for individual refractive correction for users with visual impairments.

[0134] In order to make the air gaps 26, 27 as thin as possible, to make the thickness of the outer and inner lenses 24, 25 as small as possible and / or to provide the outer and inner lenses 24, 25 with the lowest possible weight, both the outer lens 24 and the inner lens 25 each have a sandwich-like composite or a stack of a plastic shell 30, 32 and a reinforcing shell 31, 33, wherein the respective reinforcing shell 31, 33 has a higher bending stiffness than the respective plastic shell 30, 32.

[0135] The plastic shell 30 and the reinforcing shell 31 of the outer lens 24 can, in particular, form a flush circumferential edge of the outer lens 24. One can also say that the circumferential edges of the plastic shell 30 and the reinforcing shell 31 are aligned or flush. Additionally or alternatively, neither the plastic shell 30 nor the reinforcing shell 31 extends laterally beyond the plastic shell 30.

[0136] The outer lens 24 has a lens side 34 facing the channel shell 13 and a lens side 35 facing away from the channel shell 13, and the channel shell 13 has a channel side 36 facing the outer lens 24, wherein the lens side 34 and the channel side 36 are spaced apart from each other such that the air gap 26 exists between them to allow total internal reflection of the light beams L1 guided in the light guiding channel 21 at the channel side 36. Similarly, the inner lens 25 has a lens side 37 facing the channel shell 13 and a lens side 38 facing away from the channel shell 13, and the channel shell 13 has a channel side 39 facing the inner lens 25, wherein the lens side 37 and the channel side 39 are spaced apart from each other such that the air gap 27 exists between them to allow total internal reflection of the light beams L1 guided in the light guiding channel 21 at the channel side 39.

[0137] Since the outer and inner lenses have essentially the same structure, the outer lens 24 will be described primarily below. Patent attorneys

[0138] GEYER, FEH NERS & PARTNER

[0139] Munich - Jena

[0140] 15 The outer lens 24 is designed such that, under pressure loads occurring during normal use (e.g., when cleaning the spectacle lens 3), it deforms but does not touch the canal shell 13 or, when deformed, maintains a distance of at least twice the wavelength of approximately 1 pm, in order not to disturb the desired total internal reflection in the canal shell 13 and / or to avoid damage to the canal side 36 that could impair the desired total internal reflection in the canal shell 13. The same applies to the inner lens 25.

[0141] Figure 3 shows the deflection of the outer lens 24 when a compressive force P1 is applied to the front surface 23. The deflected outer lens 24 is shown with solid lines, and the non-deflected outer lens 24 (when no compressive force P1 is applied) is shown with dotted lines. The same representation is shown for the deflected inner lens 25 (due to a compressive force P2) in Figure 3.

[0142] The bending stiffness D, characterized by the product of the modulus of elasticity E and the area moment of inertia I (D = E • I), is therefore selected accordingly for the outer lens 24. Thus, the effective modulus of elasticity of the outer lens 24 can be adjusted by combining the thin plastic shell 30 with the reinforcing shell 31, made of, for example, glass, so that the desired bending stiffness for the outer lens 24 is achieved. Compared to a conventional outer lens made entirely of plastic, the desired bending stiffness can be achieved with a smaller form factor (e.g., thickness and / or weight of the outer lens 24).

[0143] Provided that the outer lens 24 is clamped all around the edge (e.g. by means of the mount 40), the maximum deflection w can be determined. maxThe composite of plastic shell 30 and reinforcing shell 31 is calculated as follows, assuming a circular disk of constant thickness for both the plastic shell 30 and the reinforcing shell 31: where P is the compressive force, r is the radius of the respective shell 30, 31 and D is the bending stiffness of the

[0144] Outer lens 24 with 0 = is. ​​Each shell / 'has the thickness t t , the

[0145] Elastic modulus E^ and Poisson's ratio Thus, shell thickness (design) and

[0146] The modulus of elasticity (material selection) is an important parameter for influencing deflection.

[0147] If the outer and inner lenses 24, 25 are each designed in the conventional manner as pure polymer lenses 24', 25', a deflection would occur under a pure point load P1' and P2'. Patent attorneys

[0148] GEYER, FEH NERS & PARTNER

[0149] Munich - Jena

[0150] 16 result, as shown schematically in Figure 4. In this process, the polymer lens 24', 25' can undesirably touch the canal shell 13'.

[0151] When testing spectacle lenses, for example, a central point load P of 100 N is applied. Based on such a central point load, the thickness t and the mass m of the polymer lens 24', 25' can be calculated as a function of the air gap thickness g as follows, where the polymer lens 24', 25' is approximated as a circular disk of constant thickness:

[0152] 3 3Pr 2 (lv 2 )

[0153] -J 4nEg with central compressive force P = 100 N, radius r of the polymer lens 24', 25', where r = 25 mm, and elastic modulus E and transverse contraction v of the polymer material of the polymer lens 24', 25', where E = 3.5 GPa and v = 0.35. The mass m can then be calculated as follows: m = pnr 2t where the density p of the polymer material of the polymer lens 24', 25' 1.34 g / cm³ 3 amounts.

[0154] Figure 5 shows the thickness t and mass m of the polymer lens 24', 25' as a function of the air gap thickness g. With an air gap thickness g of 0.2 mm, the polymer lens 24', 25' has a thickness of approximately 2.65 mm and a mass m of approximately 7 grams.

[0155] Figures 6A-6C show the reduced thickness of the outer lens 24 compared to a pure polymer disk 24', 25' according to Figure 4 due to the increased flexural stiffness for plastic shells 30 of varying thicknesses, depending on the air gap thickness g. In Figure 6A, the thickness of the plastic shell 30 is 0.5 mm, in Figure 6B 1.0 mm, and in Figure 6C 1.5 mm. The thickness of the entire outer lens 24 is shown with a solid line K1, the thickness of the reinforcing shell 31 with a dotted line K2, and the thickness of an equivalent polymer disk 24', 25', which would have the same flexural stiffness, with a dashed line K3. In Figures 6A-6C, the respective thicknesses in mm are shown along the ordinate, and the air gap thickness g in mm is shown along the abscissa.

[0156] The arrows R1-R3 indicate the achievable thickness reduction of the outer shell 24 compared to the pure polymer lens 24', 25'. Patent attorneys

[0157] GEYER, FEH NERS & PARTNER

[0158] Munich - Jena

[0159] Figures 7A-7C show the total mass of the outer lens 24 compared to a pure polymer disk 24', 25' according to Figure 4 for different thicknesses of plastic shells 30 as a function of the air gap thickness g. In Figure 7A, the thickness of the plastic shell 30 is 0.5 mm, in Figure 7B 1.0 mm, and in Figure 7C 1.5 mm. The mass of the entire outer lens 24 is shown with a solid line K4, the mass of the reinforcing shell 31 with a dotted line K5, and the mass of an equivalent polymer disk 24', 25', which would have the same bending stiffness, with a dashed line K6. In Figures 7A-7C, the respective masses are shown in grams along the ordinate and the air gap thickness g in mm along the abscissa.

[0160] The arrows R4 and R5 in Figures 7A and 7B show the achievable thickness reduction of the outer shell 24 compared to the pure polymer disk 24', 25'. Figure 7C shows an increase in mass with a thicker plastic shell 30.

[0161] The results according to Figures 6A-6C and 7A-7C show the potential of the composite approach for the outer lens 24 and the inner lens 25 to reduce the form factor, especially when thin plastic shells 30, 32 are used.

[0162] In the display device 1 according to the invention, the virtual image is projected into the user's field of vision via the first lens 3. Projection via the second lens 4 is also possible. Furthermore, the display device 1 can be designed such that information or virtual images are projected via both lenses 3 and 4. The projection can be arranged to create a three-dimensional image impression. However, this is not mandatory.

[0163] The lenses 3, 4 can have a refractive power of zero or a non-zero refractive power (particularly for correcting a refractive error). In particular, both the front surface 23 and the back surface 11 can be curved. The front surface 23 is specifically spherically curved. However, the front surface 23 can generally be spherically, aspherically, toricly, and / or freeformly curved. If the lens 3, 4 has a non-zero refractive power to correct a refractive error, the curvature of the back surface 11 is usually chosen accordingly to achieve the corresponding correction. The back surface 11 can have a curvature other than spherical (including a shape that provides a progressive or multifocal lens effect). In general, the back surface can be spherically, aspherically, toricly, and / or freeformly curved.Of course, it is also possible that the curvature of the back, together with the curvature of the front, achieves the desired correction of refractive error. Patent attorneys.

[0164] GEYER, FEH NERS & PARTNER

[0165] Munich - Jena

[0166] 18

[0167] The holding device 2 need not be designed as a spectacle-like holding device. Any other type of holding device is also possible, with which the display device 1 can be placed on and worn on the head.

Claims

patent attorneys GEYER, FEH NERS & PARTNER Munich - Jena 19 tooz technologies GmbH Attorney's file: PAT 4377 / 070-PCT Patent claims 1. Spectacle lens for a display device (1) that can be placed on a user's head and generates an image, wherein the spectacle lens (3) has a front (23) and a back (11), an entry section (28) and a deflection section (18) spaced apart from the entry section (28), and a light guiding channel (21), wherein the spectacle lens (3) has a channel shell (13) in which the light guiding channel (21) runs and a first lens (24; 25), wherein the light guiding channel (21) guides light beams (L1) of the generated image, which are coupled into the spectacle lens (3) via the entry section (28), to the deflection section (18), from which they are deflected to exit the spectacle lens (3) via the back (11), wherein the first lens (24; 25) has a first lens side (34; 37) facing the channel shell (13). as well as a second lens side (35; 38) facing away from the canal shell (13) and the canal shell (13) one of the first lenses (24;25) having a first channel side (36; 39) facing the first channel side (34; 25), wherein the first lens (24; 25) has an imaging effect, wherein the first lens side (34; 37) and the first channel side (36; 39) are spaced apart from each other such that a first air gap (26; 27) exists between them to allow total internal reflection of the light beams (L1) guided in the light guidance channel (21) at the first channel side (36; 39), characterized in that the first lens (24; 25) has a first stack of a first plastic shell (30; 32) and a first reinforcing shell (31; 33), wherein the first reinforcing shell (31; 33) has a higher bending stiffness than the first plastic shell (30; 32).

2. Spectacle lens according to claim 1, wherein the bending stiffness is the product of the modulus of elasticity and the area moment of inertia, and wherein the modulus of elasticity of the first reinforcing shell (31; 33) is at least ten times the modulus of elasticity of the first plastic shell (30; 32). patent attorneys GEYER, FEH NERS & PARTNER Munich - Jena 20 3. Spectacle lens according to one of the above claims, wherein the first reinforcing shell (31 ; 33) comprises glass material, transparent ceramic material and / or at least one diamond layer.

4. Spectacle lens according to one of the above claims, wherein the first reinforcing shell (31 ; 33) comprises a laminate of several different materials.

5. Spectacle lens according to one of the above claims, wherein the first plastic shell (30; 32) comprises a polymer material.

6. Spectacle lens according to one of the above claims, wherein the first plastic shell (30; 32) and / or the first reinforcing shell (31; 33) effect the imaging action of the first lens.

7. Spectacle lens according to one of the above claims, wherein both the first plastic shell (30; 32) and the first reinforcing shell (31; 33) in the first stack extend to a circumferential edge of the first lens (24; 25).

8. Spectacle lens according to one of the above claims, wherein a first clamping unit (40; 41 ) is provided which clamps the first lens (24; 25) circumferentially.

9. Spectacle lens according to claim 8, wherein the first clamping unit (40; 41 ) seals the first air gap in a gas- and moisture-tight manner and / or ensures athermalization of the spectacle lens.

10. Spectacle lens according to one of the above claims, wherein the first lens (24; 25) is refractive and / or diffractive.

11. Spectacle lens according to one of the above claims, wherein the first lens (24; 25) is designed as a Fresnel lens.

12. Spectacle lens according to one of the above claims, wherein the difference between the refractive index of the first plastic shell (30; 32) for a first wavelength of 550 nm and the refractive index of the first reinforcing shell (31; 33) for the first wavelength is less than or equal to 0.

2.

13. Spectacle lens according to one of the above claims, wherein the side of the first plastic shell (30; 32) facing the first reinforcing shell (31; 33) has an anti-reflective coating and / or wherein the side of the first reinforcing shell (31; 33) facing the first plastic shell (30; 32) has an anti-reflective coating. patent attorneys GEYER, FEH NERS & PARTNER Munich - Jena 21 14. Spectacle lens according to one of the above claims, wherein the first plastic shell (30; 32) is connected to the first reinforcing shell (31; 33) with a releasable adhesive, wherein preferably the difference between the refractive index of the first plastic shell (30; 32) for the first wavelength and the refractive index of the adhesive for the first wavelength is less than or equal to 0.

1.

15. Spectacle lens according to one of the above claims, wherein the side of the first plastic shell (30; 32) facing away from the first reinforcing shell (31; 33) has an anti-reflective coating and / or wherein the side of the first plastic shell (30; 32) the guiding side of the first reinforcement shell (31 ; 33) has an anti-reflective coating.

16. Spectacle lens according to one of the above claims, wherein the side of the first plastic shell (30; 32) facing away from the first reinforcing shell (31 ; 33) has a hard coating.

17. Spectacle lens according to one of the above claims, wherein a second lens is provided, the lens having a third lens side facing the channel shell and a fourth lens side facing away from the channel shell, and the channel shell having a second channel side facing the second lens, wherein the second lens has an imaging effect, wherein the third lens side and the second channel side are spaced apart from each other such that a second air gap exists between them to enable total internal reflection of the light beams guided in the light-guiding channel at the second channel side, wherein the second lens has a second stack of a second plastic shell and a second reinforcing shell, wherein the second reinforcing shell has a higher bending stiffness than the second plastic shell.

18. Display device comprising a holding device (2) that can be placed on the head of a user, an image generation module (5) attached to the holding device (2) which generates an image, and a spectacle lens (3) attached to the holding device (2) according to one of the above claims, wherein the generated image is coupled into the spectacle lens via the entry section (28), guided in the channel shell (13) by at least one internal total reflection to the deflection section (18) and deflected at the deflection section (18) to exit the spectacle lens (3) via the back side, so that the user can perceive the generated image as a virtual image when the holding device (2) is placed on the head.

Images