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) is of multi-shell construction and has a channel shell (13), in which the light guiding channel (21) extends, and an inner shell (25), wherein the inner shell (25) takes the form of a Fresnel lens (25) with negative refractive power, wherein the Fresnel lens (25) has a first lens (31) with a Fresnel-patterned surface (33), which faces the channel shell (13), and a second lens (32), wherein the Fresnel-patterned surface (33) has alternately curved active surfaces (34) and interfering flanks (35) connecting the curved active surfaces (34), wherein the Fresnel-patterned surface (33) is configured in such a way as to be free of overhang, wherein the second lens (32) fills the Fresnel-patterned surface (33) in a form-fitting manner, and wherein the first lens (31) has a lower refractive index than the second lens (32).

Description

[0001] Spectacle lens for a display device that can be placed on the head of a user and generates an image, and display device with such a spectacle lens

[0002] The present invention relates to a spectacle lens having the features of the preamble of claim 1 and a display device having such a spectacle lens.

[0003] A spectacle lens of the type mentioned above is known from WO 2015 / 158833 A1. Such spectacle lenses can be used, for example, in a display device that can be placed on a user's head and generates an image, to provide so-called data glasses.

[0004] For such lenses, form factor and weight are critical factors because, when used as intended, they are used in a display device that is worn on a user's head.

[0005] 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 producing such a spectacle lens are to be provided.

[0006] The invention is defined in independent claims 1, 16 and 18. Advantageous further developments are specified in the dependent claims.

[0007] A spectacle lens is provided for a display device that can be placed on the head of a user and generates an image, the spectacle lens having a front and a back, an entrance section and a deflection section spaced from the entrance section, and a light guide channel. The spectacle lens has a multi-shell construction and has a channel shell in which the light guide channel runs, and an inner shell. The light guide channel extends from the entrance section to the deflection section and guides light beams of the generated image, which are coupled into the spectacle lens via the entrance section of the spectacle lens, to the deflection section (e.g. by at least one reflection), from which they are deflected to exit the spectacle lens via the inner shell.The inner shell is designed as a Fresnel lens with negative refractive power and comprises a first lens with a Fresnel-structured surface facing the channel shell, and a second lens. The Fresnel-structured surface facing the channel shell comprises alternating curved active surfaces and interference flanks connecting the curved active surfaces and is designed to be free of overhangs. The second lens fills the Fresnel-structured surface with a form-fitting fit and has a higher refractive index than the lens.

[0008] This Fresnel lens design allows for a spectacle lens with a small form factor and a low weight. At the same time, it is possible to correct vision defects using the Fresnel lens, and the Fresnel lens is easy to manufacture because its Fresnel-structured surface is free of overhangs. In particular, the technically limited and costly production of Fresnel structures with overhangs is unnecessary. For the first lens free of overhangs, standard processes (such as injection molding) can be used for production.

[0009] The interface of the first lens, which is simulated by the Fresnel-structured surface, can be convexly curved. This facilitates the formation or design of the Fresnel-structured surface so that it is free of overhangs.

[0010] The side of the second lens facing the channel shell can be curved. In this case, for example, there can be an air gap between the second lens and the channel shell.

[0011] Due to the curved design of the side of the second lens facing the canal shell, there is another optically effective surface or interface that can be used, for example, to correct vision defects.

[0012] The side of the first lens facing away from the channel shell may be curved.

[0013] Due to the curved design of the side of the first lens facing away from the canal shell, there is another optically effective surface or interface that can be used, for example, to correct vision defects.

[0014] In the case of the spectacle lens, at least one (in particular several or even all) of the interference flanks can be located in a shadow area that is not visually perceptible to the user during the intended use of the spectacle lens. The shadow area can, for example, be a solid angle area. For each area in which an interference flank is to be formed, one can define a shadow area that is not visually perceptible to the user during the intended use of the spectacle lens.When determining the shadow area, the refractive index of the inner shell, the refractive index of the second lens, the refractive power of the inner shell, the refractive power of the second lens, the curvature of the interface simulated by the Fresnel-structured surface, the curvature of the interface of the first lens facing away from the Fresnel-structured surface, and / or the lens-to-eye distance of the user for whom the lens is intended can be taken into account. The lens-to-eye distance of the user is understood to mean, in particular, the distance of the lens from a defined point on the eye (e.g., corneal vertex or ocular rotation point) during intended use.

[0015] The light guide channel can have a first and a second reflection surface, each extending from the entrance section to the deflection section, on which the light beams of the generated image are reflected. At least one of the two reflection surfaces can be designed as a flat surface.

[0016] The first reflection surface and / or the second reflection surface can be realized by a refractive index jump that ensures total internal reflection.

[0017] The refractive index jump can occur between the first shell and a layer (e.g. an adhesive layer) arranged between the first and the second or third shell.

[0018] The first reflection surface and / or the second reflection surface are / is thus formed by the interface of the first shell to the layer (e.g. to the adhesive layer).

[0019] The refractive index jump can occur between the first shell and the second or third shell.

[0020] The first reflection surface and / or the second reflection surface are / is thus formed by the interface of the first shell to the first or second shell.

[0021] The first and / or second reflection surface can be configured, for example, such that it only reflects the light beams if their angle of incidence is greater than a predetermined first critical angle. Furthermore, the first and / or second reflection surface can be configured such that it is transmissive for angles of incidence in the range from 0° to a predetermined second critical angle of less than 90°. The second critical angle is less than or equal to the first critical angle. These transmission / reflection properties are preferably present for radiation in the visible wavelength range.

[0022] The first critical angle can be, for example, in the range of 45° - 65°, preferably in the range of 50° - 60°. The second critical angle can be, for example, in the range of 30° - 60°, preferably in the range of 35° - 45°.

[0023] The first and / or second reflection surface can comprise an interference layer system or be formed as an interference layer system. The interference layer system can be formed from at least two different materials with different refractive indices. In particular, the interference layer system can comprise two, three, four, five, or more different materials. The refractive indices of the materials can be in the range from 1.4 to 2.5 at a wavelength of 546 nm.

[0024] The second lens may be made of an optical plastic material which in particular contains nanoparticles (e.g. TiO2, ZrO2 and / or diamond nanoparticles).

[0025] Since the optical path length through the second lens is typically on the order of a few hundred microns, scattering from such nanoparticles is likely a negligible problem. By using nanoparticles, not only the dispersion but also the average refractive index of the medium can be adjusted.

[0026] The second lens may be made of an adhesive which cures or is cured after being positively filled and / or introduced into the space between the channel shell and the first shell, of a thermally formable material, of a liquid (which may, for example, be encapsulated) and / or of a gel (which may, for example, be encapsulated).

[0027] The first lens and / or the second lens can each be designed as a GRIN lens (or as a gradient lens or gradient index lens). This is understood in particular to mean that the lens effect is caused by a (preferably continuous) change in the refractive index in the material of the respective lens.

[0028] The spectacle lens may have an outer shell arranged such that the channel shell lies between the inner shell and the outer shell, the outer shell having a positive refractive power. The first lens may have a refractive index m and an Abbe number vi, the second lens may have a refractive index n2 and an Abbe number v2, and the outer shell may have a refractive index ns and an Abbe number vs, wherein materials with such refractive indices and the Abbe numbers may be selected such that

[0029] Under the condition that AP ges should be as small as possible, it is understood here in particular that APges is chosen so that p is the effective Abbe number v e rr = 9es larger or comparable to typical spectacle lenses Pges is chosen, i.e. v e y > 20, v e y > 30, v e y > 40 or v e y > 50. The curvature of the side of the outer shell facing away from the waveguide is defined as pp U sh and the boundary surface of the first lens, simulated by means of the Fresnel-structured surface, is called pp u ii. The total refractive power of the lens is denoted by Ptotal. The difference between the refractive power in the blue and the refractive power in the red spectral range is called AP ge s is called.

[0030] The material of the second lens can fix the first lens to the canal shell.

[0031] Furthermore, the material of the second lens can be tinted. The tint can be permanent. However, it is also possible for the second lens to be switchable between tinted and untinted. For example, an electrochromic material and / or an electrochromic layer can be used for the second lens.

[0032] The second lens can have at least one active lens (e.g., liquid crystals) with adjustable refractive power. Such an active lens allows for a tunable refractive power for vision correction or, in combination with another active element, for a variably adjustable focus position of the virtual image.

[0033] Furthermore, a liquid or a moldable material can be used as the material for the second lens.

[0034] The refractive index of the second lens (or the medium in the space between the first lens and the channel shell) can be adjusted, e.g., by adding a variable proportion of nanoparticles and / or selecting a suitable plastic, which allows for continuous variation of the refractive index. This allows the overall refractive power of the Fresnel lens to be individually adapted to the user within certain limits using the same first lens. Thus, customized vision correction can be provided for the widest possible range of users using as few variants of the first lens as possible. Fewer variants allow for standardization of manufacturing processes and the use of fewer tools, thus reducing costs.

[0035] The advantageous angular range within which the interference edges can be aligned depends particularly on the difference in the refractive index of the first and second Fresnel lens elements. This dependence can be used to customize the lens for different corneal vertex distances (CVDs) as well as different distances between the cornea and the eyeball's center of rotation. Thus, the same first Fresnel lens element can be used for a wider range of users.

[0036] The spectacle lens can have an exit section on the rear side through which the deflected light beams exit the lens. Furthermore, the deflection section can redirect the light beams guided to it toward the exit section in such a way that they exit the lens through the exit section and are thus decoupled from the lens.

[0037] 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 grating.

[0038] In the first spectacle lens, the deflection section can have a single reflective or partially reflective deflection element or a plurality of reflective and / or partially reflective deflection elements arranged next to one another. With a plurality of reflective or partially reflective deflection elements arranged next to one another, a desired deflection function and, if appropriate, a certain imaging function of the deflection section can be realized, for example in a Fresnel-like manner (this can of course also be realized with a single reflective or partially reflective deflection element). The reflective or partially reflective deflection elements can be reflective or partially reflective surface pieces, which can also be referred to as reflective or partially reflective facets. The reflective or partially reflective surface pieces can each be flat. However, it is also possible for the reflective orThe partially reflective surface pieces themselves are curved (for example, spherically, aspherically, or free-form). Similarly, the single reflective or partially reflective deflection element can be flat or curved (for example, spherically, aspherically, or free-form). 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 for deflection.

[0039] The reflectivity of the respective reflective deflection elements (or of the single reflective deflection element) can, for example, be in the range of 2 - 100% (including the range limits). Thus, the reflective deflection elements can be partially reflective or reflective.

[0040] Each of the shells (in particular the channel shell) can be designed as a plane-parallel plate, as a plate with one curved side, or as a plate with two curved sides. The facing sides of two shells connected to each other (e.g., by means of an adhesive layer) can preferably have complementary curvatures.

[0041] The spectacle lens according to the invention can, in particular, have a curved rear side and / or a curved front side. The entrance section can be formed in the rear side and / or in the channel shell.

[0042] The light beams of the image generation module are preferably guided to the deflection section by one or more reflections (in particular total internal reflections).

[0043] If the parting plane or the surface of the first shell and / or the further shells exhibits changes in curvature, e.g. in order to influence the light conduction in the first shell, an index match of the adhesive to the first shell and / or the second or third shell is useful, as this has a positive influence on the transparency performance.

[0044] Each of the bowls can be made of glass or plastic.

[0045] A display device is provided with a holding device that can be placed on the head of a user, an image generation module that is fastened to the holding device and generates an image, and a spectacle lens according to the invention (including all further developments) that is fastened to the holding device. The generated image is coupled into the first shell via an entry section, guided in the first shell by at least reflection to the deflection section, and deflected at the first deflection section to exit the spectacle lens via the inner shell, so that the user can perceive it as a virtual image when the holding device is placed on the head. The display device can have 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.

[0046] The image generation module and / or an image generator unit of the image generation module can / may, in particular, comprise a planar image generator, such as an LCD module, an LCoS module, an OLED module, a pLED, or a tilting mirror array. Each image generator can comprise a plurality of pixels, which can be arranged, for example, in rows and columns. Each image generator can, for example, be self-luminous or non-self-luminous.

[0047] Each imager can preferably produce a monochromatic image, whereas different imagers can produce monochromatic images at different wavelengths.

[0048] The imaging module can, for example, comprise a polychromatic imager, a combination of two or more monochromatic imagers, or a combination of a duochromatic imager and a monochromatic imager. Typical configurations of such imaging modules with multiple imagers comprise an overlay unit that overlays the light beams of the multiple imagers into a common light beam. Such an overlay unit can be implemented, for example, as a beam splitter cube (also called an X-cube) or as a so-called rod combiner, which are known to those skilled in the art.

[0049] The image generation module can generate the image with a first lateral chromatic aberration that (partially or completely) compensates for a second lateral chromatic aberration in the virtual image generated by the spectacle lens.

[0050] Since the out-coupling deflection section should be as invisible as possible and also interfere as little as possible with the light arriving from the surroundings to the viewer's eye, deflection sections are generally preferred that have high transmission in the transparent state and thus low reflectivity for the light beam(s) to be coupled out of the at least two-color image. Typical values ​​for the ratio of reflection to transmission are 50%, 30%, 10%, or 2%, uniformly across the visible wavelength range.

[0051] A method for producing a spectacle lens according to the invention (including all further developments) is provided, which comprises the following steps: A) producing the first lens with the Fresnel-structured surface and form-fitting filling of the Fresnel-structured surface with the material of the second lens in order to produce the Fresnel lens,

[0052] B) Providing the channel shell, and

[0053] C) mechanically bonding the Fresnel lens to the channel shell to produce the ophthalmic lens.

[0054] The following sub-steps can be carried out in step A:

[0055] A1 ) Producing at least two different types of the first lens with different Fresnel-structured surfaces,

[0056] A2) Selecting a type of the first lens depending on a desired total refractive power of the inner shell and a lens-to-eye distance of a user for whom the spectacle lens is intended, A3) Selecting the refractive index of the second lens such that an adaptation to the desired total refractive power of the inner shell and to the lens-to-eye distance of the user for whom the spectacle lens is intended is carried out.

[0057] The lens-to-eye distance of the user is understood to mean in particular the distance of the lens from a defined point of the eye (e.g. corneal vertex or eye rotation point) when used as intended.

[0058] In step A3, the refractive index of the second lens can further be selected such that at least one of the interference edges (in particular several or all of the interference edges) lies in a shadow area which is not optically detectable by the user during the intended use of the spectacle lens.

[0059] The shadow area can, for example, be a solid angle area. For each area in which an interference flank is to be formed, a shadow area can be defined that is not optically perceptible to the user during intended use of the spectacle lens. When determining the shadow area, the refractive index of the inner shell, the refractive index of the second lens, the refractive power of the inner shell, the refractive power of the second lens, the curvature of the interface recreated by the Fresnel-structured surface, the curvature of the interface of the first lens facing away from the Fresnel-structured surface, and / or the lens-to-eye distance of the user for whom the spectacle lens is intended can be taken into account.It is understood that the features mentioned above and those to be explained below can be used not only in the combinations indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

[0060] The invention is explained in more detail below using exemplary embodiments with reference to the attached drawings, which also disclose features essential to the invention. These exemplary embodiments are for illustrative purposes only and are not to be interpreted as restrictive. For example, a description of an embodiment with a large number of elements or components should not be interpreted to mean that all of these elements or components are necessary for implementation. Rather, other embodiments may also contain alternative elements and components, fewer elements or components, or additional elements or components. Elements or components of different embodiments may be combined with one another unless otherwise stated. Modifications and variations described for one of the embodiments may also be applicable to other embodiments.To avoid repetition, identical or corresponding elements in different figures are designated by the same reference numerals and are not explained more than once. The figures show:

[0061] Fig. 1 is a schematic perspective view of an embodiment of the display device according to the invention;

[0062] Fig. 2 is an enlarged partial sectional view of the first spectacle lens including a schematic representation of the first image generation module according to Fig. 1;

[0063] Fig. 3 is an enlarged partial sectional view of the first spectacle lens according to Fig. 1; Fig. 4 is an enlarged view of detail B of Fig. 3;

[0064] Fig. 5 is an enlarged view of a Fresnel-structured surface with overhang;

[0065] Fig. 6 is an enlarged partial sectional view of a spectacle lens according to another embodiment of the invention;

[0066] Fig. 7 is an enlarged partial sectional view of a spectacle lens according to another embodiment of the invention;

[0067] Fig. 8 is an enlarged partial sectional view of a spectacle lens according to another embodiment of the invention;

[0068] Fig. 9 is an enlarged partial sectional view of a spectacle lens according to another embodiment of the invention;

[0069] Fig. 10 is a schematic lens section of the Fresnel lens 15, and Fig. 11 is an enlarged partial sectional view of the first spectacle lens including a schematic representation of the first image generation module according to a further embodiment of the invention.

[0070] In the embodiment shown in Fig. 1, the display device 1 according to the invention comprises a holding device 2 which can be placed on the head of a user and which can be designed, for example, in the manner of a conventional spectacle frame, as well as a first and a second spectacle lens 3, 4 which are fastened to the holding device 2. The first spectacle lens 3 and / or the second spectacle lens 4 can be designed individually as spectacle lenses according to the invention or as a spectacle lens according to the invention. The holding device 2 with the spectacle lenses 3, 4 can be designed, for example, as sports glasses, sunglasses and / or glasses for correcting ametropia, wherein a virtual image can be projected into the user's field of vision via the first spectacle lens 3, which can also be referred to as a multifunctional lens, as described below.

[0071] For this purpose, the display device 1 comprises a first image generation module 5, which can be arranged in the region of the right temple of the holding device 2, as shown schematically in Fig. 1.

[0072] The first image generation module 5 can have a first image generator unit 7 for generating a first image, as shown schematically in Fig. 2. For this purpose, the first image generator unit 7 comprises a first planar image generation element 8, downstream of which a first image generator optics 9 is arranged. The first planar image generation element 8 can have, for example, an OLED element, an LCD element, an LCoS element, a pLED or a tilting mirror matrix, each of which comprises a multiplicity 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 first planar image generation element 8.

[0073] As can further be seen from Fig. 2, a control unit 10 with, for example, a processor P and a memory M is provided for controlling the first image generation module 5. The control unit 10, which can be arranged, for example, on the holding device 2, controls the first image generation module 5 and in particular the first image generation element 8 as a function of supplied image data such that a first image is generated in accordance with the image data. The light beams L1 emitted by the first image generation element 8 pass through the first imaging optics 9 and then enter the first spectacle lens 3. The region of the entrance can also be referred to as the entrance surface 12. The first spectacle lens 3 is of multi-shell design and has a channel shell 13 as well as an outer shell 24 and an inner shell 25.The channel shell 13 is the middle shell located between the outer shell 24 and the inner shell 25. The shells 13, 24, 25 are connected to one another in such a way that a reflection surface 26 (hereinafter also referred to as the outer reflection surface 26) is provided between the channel shell 13 and the outer shell 24, and a reflection surface 27 (hereinafter also referred to as the inner reflection surface 27) is provided between the channel shell 13 and the inner shell 25. Alternatively, it is possible for the surface of the channel shell 13 to be the reflection surface and / or for the light to be guided in the channel shell 13 by total internal reflection.

[0074] In the embodiment described here, the channel shell 13 is designed as a plane-parallel plate with the exception of the area of ​​the entrance surface 12. The inner shell 25 is designed as a Fresnel lens 25 with negative refractive power, as will be described in more detail below. 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 side 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 side 11 of the first spectacle lens 3.

[0075] The outer reflection surface 26 can be realized by an angle-dependent reflection layer 26, which reflects the light beams L1 only when their angle of incidence 9 E relative to the surface normal F (shown as a dashed line in Fig. 2) of a surface element at which the reflection is to take place, is greater than a predetermined first critical angle 0G The outer reflection surface 26 can further be designed to be transmissive for angles of incidence in the range from 0° to a predetermined second critical angle of less than 90°. The second critical angle is less than or equal to the first critical angle 0 G .

[0076] These transmission / reflection properties are preferential for radiation in the visible wavelength range.

[0077] The angle-dependent outer reflection surface 26 can be designed, for example, as an interference layer system, which, for example, has alternating thin layers with higher and lower refractive indices. In the general case, the interference layer system can consist of k optical layers Si, S2, ... Sk (k > 2) made of m materials Mi ... M m(m > 2), which differ in their refractive indices Ni... Nj (j > 2). Specific examples of such an interference layer system are described, for example, in WO 2015 / 158833 A1, and therein in particular on page 4, lines 16-30, page 9, line 34 - page 10, line 31 in conjunction with Figures 3-5, and on page 11, lines 5-26 in conjunction with Figures 7-10. The corresponding disclosure is hereby incorporated into the present description.

[0078] The inner reflection surface 27 can be designed in the same way as the outer reflection surface 26

[0079] It is further possible for the outer and / or inner reflection surface 26, 27 to be realized by a transparent adhesive layer whose refractive index is lower than the refractive index of the channel shell 13, wherein the refractive indices are selected such that the light beams are guided in the channel shell 13 by total internal reflection. The outer and / or inner reflection surface 26, 27 is thus formed by the interface between the channel shell 13 and the respective adhesive layer.

[0080] It is also possible for the outer reflection surface 26 to be realized by a refractive index jump between the channel shell 13 and the outer shell 24, whereby the refractive index of the outer shell 24 is lower than the refractive index of the channel shell 13. The precise refractive index values ​​are selected such that the light beams in the channel shell 13 are guided by total internal reflection. The outer reflection surface 26 is thus formed by the interface between the channel shell 13 and the outer shell 24. Alternatively, the outer reflection surface 26 can be realized by a surface coating of the channel shell 13 with a material with a lower refractive index.

[0081] Furthermore, the channel shell 13 has a buried first deflection section 18 which comprises one (or more, not shown in Fig. 2) partially reflective deflection element 19, which can also be referred to as partially reflective facet 19.

[0082] As already described, the light beams L1 enter the first spectacle 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 exemplary embodiment described here, protrudes 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) deflection surface 29, which deflects the light beams L1 in a first direction (here the y-direction) toward the deflection section 18 such that the light beams L1 are guided by reflections on both reflection surfaces 26, 27 in the channel shell 13 to the first deflection section 18. To ensure that this guidance can take place in the channel shell 13, both reflection surfaces 26, 27 each extend from the entrance section 28 to the first deflection section 18.The first deflection section 18 then deflects the light beams L1 such that the deflected light beams L1 exit the first spectacle lens 3 via the Fresnel lens 25 and thus via the rear side 11, thus creating a virtual image that the user can perceive with his 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.

[0083] Thus, a first light guide channel 21 is present in the channel shell 13, which extends along the first direction from the entry section 12 to the first deflection section 18.

[0084] 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 referred to as a waveguide), the inner shell 25 has a negative refractive power to pull the focus position of the virtual image into the near range for the user (e.g., 0.5 m - 2 m). Therefore, the inner shell 25 can also be referred to as a pull lens 25.

[0085] For viewing the surroundings, the influence of the pull lens 25 is compensated by the outer shell 24 with positive refractive power. Therefore, the outer shell 24 can also be referred to as a push lens 24. Since the outer shell 24 can also be omitted, it is shown in dashed lines in Fig. 2 (together with the outer reflective layer 26). The outer shell 24 can be omitted, for example, if the focus position of the virtual image is not adjusted. In this case, the pull lens 25 is preferably only needed for correcting ametropia.

[0086] In addition to adjusting the focal plane of the virtual image, the pull lens 25 can be used for individual refraction correction for visually impaired users.

[0087] As can be seen in the sectional view of the first spectacle lens 3 of Figs. 1 and 2 shown in Fig. 3, the inner shell 25 is formed in two parts and comprises a first lens 31 and a second lens 32.

[0088] The first lens 31 has a Fresnel-structured surface 33 facing the channel shell 13. As can be seen in particular from the enlarged view of detail B of Fig. 3 in Fig. 4, the Fresnel-structured surface 33 comprises alternating curved active surfaces 34 and interference flanks 35 connecting the curved active surfaces 34, wherein the curved active surfaces 34 provide a desired curved boundary surface in a Fresnel-like manner.

[0089] The second lens 32 is configured to form-fit the Fresnel-structured surface 33. Since the second lens 32 is made of a material with a higher refractive index than the material from which the first lens 31 is made, the Fresnel-structured surface 33 can be configured to be free of overhangs. It can also be said that the Fresnel-structured surface 33 has no undercuts. At the same time, the inner shell 25 can have a negative refractive power.

[0090] The fact that the Fresnel-structured surface 33 is free of overhangs or has no undercuts is understood here in particular to mean that there is a direction from which a projection of all peaks S does not lie on an effective surface of the Fresnel-structured surface 33. In particular, there is a solid angle range which has an opening angle of greater than 5° in at least one plane, from which a projection of all peaks S does not lie on an effective flank of the Fresnel-structured surface 33. For comparison, Fig. 5, in the same way as Fig. 4, shows an enlarged section of a Fresnel-structured surface 33' of a solution not according to the invention, in which overhangs or undercuts are present. The projection of the peaks S' lie on adjacent effective surfaces 34'. There is therefore, for example, an overhang U1.

[0091] The inner shell 25 can thus be provided as a Fresnel lens 25 with negative refractive power, wherein the Fresnel lens 25 has aligned and buried interference flanks 35 without overhang. The space between the Fresnel-structured surface 33 and the channel shell 13 is thus not filled, as is usually the case, with a medium having a lower optical refractive index than that of the first lens 31, but rather, by means of the second lens 32, with a material having a higher refractive index than the material of the first lens 31.

[0092] The material of the second lens 32 is preferably moldable during assembly of the first lens 31. This is understood here in particular to mean that the optical surface is defined by the first lens 31 or by the Fresnel-structured surface 33 and that the material of the second lens 32 fills the intermediate space in a form-fitting manner. The material of the second lens 32 can be, for example, a curable adhesive, a liquid, or another (for example, thermally) moldable material. By introducing a material with a higher refractive index between the first lens 31 and the waveguide 13, the curvature of the interface simulated by the Fresnel-structured surface 33 is convex for negative refractive powers, so that overhangs in the Fresnel-structured surface 33 are avoided.

[0093] To ensure total internal reflection in the channel shell 13 on the side facing the inner shell, the previously described inner reflection surface 27 is arranged between the channel shell 13 and the inner shell 25. The material of the second lens 32 is fundamentally freely selectable, as long as it is moldable and / or as long as a form-fitting filling of the Fresnel-structured surface 33 is possible. Curing of this material is not absolutely necessary. An encapsulated liquid is also possible. In this case, it is preferable to provide a mechanical holder (not shown) that holds the channel shell 13 and the inner shell 25.

[0094] Fig. 6 schematically shows an embodiment in which no push lens is provided and in which the pull lens 25 with buried Fresnel structure has a refractive power of -6 dpt (dpt = diopter). The pull lens 25 is made of PMMA (m = 1.49), and an adhesive for optical applications with ns = 1.9 is introduced into the space between the waveguide 13 to form the second lens 32. The optically effective surface has a radius of curvature of approximately 7 cm for this refractive index combination, and a resulting Fresnel-structured surface 33 or Fresnel surface 33 with a structure height of 0.3 mm is shown as an example in Fig. 6.

[0095] The optical insulation layer 27 (or inner reflection surface 27) on the surface of the waveguide 13 facing the eye A can be designed, for example, as a dielectric stacking sequence, as a material with a low refractive index and / or as a porous layer with, for example, n < 1.2 in order to maintain the total reflection condition.

[0096] Fig. 7 schematically shows a further exemplary embodiment, wherein the materials and the Fresnel-structured surface 33 are selected to be the same as in the exemplary embodiment described in connection with Fig. 6. However, in the exemplary embodiment according to Fig. 7, the second lens 32 with a high refractive index is not used to hold the first lens 31 on the waveguide 13. Instead, an additional optical surface 40 is provided on the side of the second lens 32 facing away from the first lens 31, and an air gap 41 is formed towards the waveguide 13. The additional optical surface 40 of the second lens 32 can, for example, be used for user-specific correction of a visual impairment (such as astigmatic visual impairment).

[0097] Fig. 8 shows an embodiment in which the surface 42 facing away from the waveguide 13 (which can be, for example, the back side 11 of the first spectacle lens 3) is not flat as before, but curved, so that an additional optical effect can be provided. The additional optical surface 42 of the first lens 31 can, for example, be used for user-specific correction of a visual impairment (such as, for example, astigmatic visual impairment). The materials and the Fresnel-structured surface 33 (or Fresnel structure 33) are selected to be the same as in the embodiment according to Fig. 6. It is also possible to design the pull lens 25 such that it has both curved surfaces 40 and 42 according to Figs. 7 and 8.

[0098] In addition to form factors, such as high thickness (e.g., edge thickness), and weight, transverse chromatic aberrations are another problem with high-power spectacle lenses. The use of the Fresnel lens 25 enables advantageous form factors. Transverse chromatic aberrations can be significantly reduced or even eliminated in the spectacle lens 3, 4 according to the invention through a suitable choice of materials.

[0099] As shown in Fig. 9, the first spectacle lens 3 comprises the push lens 24 (with a refractive index ns and an Abbe number V3) and the pull lens 25. The pull lens 25 comprises the second lens 32

[0100] (with a refractive index n2 and an Abbe number V2) and the first lens 31 (with a refractive index m and an Abbe number vi). As an example, the optical surfaces should be spherical. The curvature of the side 23 of the push lens 24 facing away from the waveguide 13 is pp Ush and the curvature underlying the Fresnel surface 33 is pp u ii.

[0101] The total refractive power and the chromatic refractive error in the visible range of this lens system can be described in good approximation as follows, neglecting the distances between the lenses 24, 31, 32:

[0102] For example, polycarbonate (ni = n3 ~ 1.59, vi = V3 ~ 29) is chosen as the material for the push lens 24 and the first lens 31. A medium with a refractive index of n2 = 2.0 is used as the filler material or the material of the second lens 32. A high refractive index in the filler material can be achieved, for example, by admixing oxide nanoparticles or diamond nanoparticles in an optical plastic material.

[0103] With this choice of material, if the push lens 24 is to have a refractive power of 1 dpt and the pull lens 25 a refractive power of -6 dpt, the push lens 24 will have a curvature of Ppush ~ l- 7 ■ l / m and for the pull lens 25 a curvature of p Puii « 14 ■ 1 / m. To minimize transverse chromatic aberrations, it is preferable that This is fulfilled for an Abbe number of the backfill material of

[0104] The light used to create the virtual image does not pass through the outer shell and therefore exhibits a different transverse chromatic aberration. This can be digitally compensated by the image sensor.

[0105] In the spectacle lens 3 according to the invention (e.g., according to Figures 3, 6-9), the refractive index of the medium in the space between the first lens 31 and the waveguide 13 (in particular the refractive index of the second lens 32) can be adjusted, e.g., by a variable proportion of admixed nanoparticles, which enables a continuous change in the refractive index. As a result, the total refractive power of the pull lens 25 can be individually adjusted to the user within certain limits using the same first lens 31. It is advantageous to provide individual vision correction for the widest possible range of users using as few variants of first lenses 31 as possible. A few variants allow processes to be standardized and a small number of tools to be used, thus saving costs. The total refractive power Pp u ii of the inner shell 25 can be approximated by

[0106] Ppull = P ( n 2 — nl. Here, p corresponds to the curvature of the interface 33i simulated by the Fresnel-structured surface 33 (as shown in the schematic lens section in Fig. 10), n2 to the refractive index of the medium of the second lens 32, and ni to the refractive index of the medium of the first lens 31.

[0107] An advantageous angular range 43, hereinafter referred to as the shadow range 43, within which the interference flanks 35 are aligned or can be located (see Fig. 10), depends on the difference in the refractive index of the first lens 31 and the filler material of the second lens 32. This dependence can be used to customize the lens for different corneal vertex distances (CVD) as well as different distances between the cornea and the eyeball's center of rotation. Analogous to the previous point, the same first lens 31 can be used for a wider range of users.

[0108] The following example serves to illustrate this: For a first HSA, an interference flank is oriented at angle ßo so that it lies in the shadow area 43 between the angles ßi ...ß2. For a second HSA, which is smaller than the first HSA, and with the same choice of media and surfaces, the shadow area shifts into the angular range ßi ..ßa', where ßi'>ßi and ßa'>ß2.

[0109] If the interference edge in the case of the second HSA is no longer in the shadow area 43, because e.g. ßo<ßi', a higher refractive index ns' of the medium of lens 32 can be selected in order to enlarge the shadow area 43 so that the original interference edge 35 is again in the shadow area 43.

[0110] The adjustment of the refractive index n2 therefore enables individual adaptation to the required refractive power and the shadow zone for a wider range of users starting from a small set of Fresneled surfaces 33.

[0111] The first image generation module 5 and the first spectacle lens 3 are designed such that a user wearing the display device 1 according to the invention on his head can perceive the first image generated by the first image generation module 5 as a first virtual image with his first eye A (here the right eye) (Figs. 1 and 2).

[0112] The first imaging unit 7 can be configured to generate and output a monochromatic (and thus single-color) image. However, it can also be configured to generate and output a multicolor image.

[0113] Furthermore, it is possible to provide several image generator units 7, 7' and 7" (Fig. 11) which, for example, generate and output a red, green and blue partial image, which is then superimposed by means of a superposition unit 45 (for example a color generator cube) to form a common beam L1, as shown for the first image generation module 5 in Fig. 10.

[0114] Depending on the reflectivity of the deflection elements 19, the first virtual image can be perceived by the user in superimposition with the surroundings. With very high reflectivity, and in particular with a reflectivity of 100%, the user can only perceive the first virtual image and not the surroundings, at least in the area of ​​the first deflection section 18, if a certain distance between the first deflection elements 19 is not exceeded. If the certain distance between adjacent deflection elements 19 is exceeded, ambient light can reach the eye unhindered between them, so that even with 100% reflectivity of the deflection elements 19, a view of the surroundings is possible, resulting in a quasi-perforated / segmented 100% mirror.

[0115] In the display device 1 according to the invention, the virtual image is projected into the user's field of vision via the first spectacle lens 3. Of course, it is also possible to project it via the second spectacle lens 4. Furthermore, the display device 1 can be designed such that information or virtual images are projected via both spectacle lenses 3, 4. The projecting can be done in such a way that a three-dimensional image impression is created. However, this is not absolutely necessary.

[0116] The spectacle lenses 3, 4 can have a refractive power of zero or a refractive power other than zero (in particular for correcting a visual impairment). In particular, both the front side 23 and the back side 11 can be curved. The front side 23 is in particular spherically curved. If the spectacle lens 3, 4 has a refractive power other than zero in order to correct a visual impairment, the curvature of the back side 11 is generally selected accordingly to achieve the corresponding correction. The back side 11 can have a curvature that deviates from the spherical shape.

[0117] The holding device 2 does not have to be designed as a glasses-like holding device. Any other type of holding device is also possible, allowing the display device 1 to be placed and worn on the head.

Claims

Patent claims 1 . Spectacle lens for a display device (1) that can be placed on the head of a user and generates an image, wherein the spectacle lens (3) has a front side (23) and a back side (11), an entry section (28) and a deflection section (18) spaced from the entry section (28), as well as a light guide channel (21), wherein the spectacle lens (3) is constructed in several layers and has a channel shell (13) in which the light guide channel (21) runs, and an inner shell (25), wherein the light guide channel (21) extends from the entry section (28) to the deflection section (18) and guides light beams (L1) of the generated image, which are coupled into the spectacle lens (3) via the entry section (28) of the spectacle lens (3), to the deflection section (18), from which they are deflected in order to exit the spectacle lens (3) via the inner shell (25), wherein the inner shell (25) is designed as a Fresnel lens (25) with negative refractive power, characterized in thatthat the Fresnel lens (25) has a first lens (31) with a Fresnel-structured surface (33) and a second lens (32), wherein the Fresnel-structured surface (33) faces the channel shell (13) and has alternating curved active surfaces (34) and interference edges (35) connecting the curved active surfaces (34), wherein the Fresnel-structured surface (33) is designed such that it is free of overhangs, wherein the second lens (32) fills the Fresnel-structured surface (33) in a form-fitting manner, and wherein the first lens (31) has a lower refractive index than the second lens (32).

2. Spectacle lens according to claim 1, wherein the boundary surface of the first lens (31) adjusted by means of the Fresnel-structured surface (33) is convexly curved.

3. Spectacle lens according to claim 1 or 2, wherein the side of the second lens (32) facing the channel shell (13) is curved.

4. Spectacle lens according to one of the above claims, wherein the side of the first lens (31) facing away from the channel shell (13) is curved.

5. Spectacle lens according to one of the above claims, wherein at least one of the interference edges (35) lies in a shadow area (43) which is not optically detectable by the user during the intended use of the spectacle lens (3).

6. Spectacle lens according to one of the above claims, in which the light guide channel (21) has a first and a second reflection surface (26, 27), each extending from the entry section (28) to the deflection section (18) and on which the light beams (L1) of the generated image are reflected, wherein preferably at least one of the two reflection surfaces (26, 27) is designed as a flat surface.

7. Spectacle lens according to one of the above claims, wherein the second lens (32) is made of an optical plastic material which in particular contains nanoparticles.

8. Spectacle lens according to one of the above claims, wherein the first lens (31) and / or the second lens (32) are / is designed as GRIN lenses.

9. Spectacle lens according to one of the above claims, wherein the spectacle lens (3) has an outer shell (24) arranged such that the channel shell lies between the inner shell (25) and the outer shell (24), the outer shell (24) having positive refractive power.

10. Spectacle lens according to claim 9, wherein the first lens (31) has a refractive index m and an Abbe number vi, the second lens (32) has a refractive index n2 and an Abbe number V2 and the outer shell (24) has a refractive index ns and an Abbe number vs, p being the effective Abbe number v e rt = 9es is chosen to be greater than 20, 30, 40 Pges or 50, wherein the curvature of the side (23) of the outer shell (24) facing away from the channel shell (21) is defined as ppush, the boundary surface of the first lens (31) simulated by means of the Fresnel-structured surface is defined as pp u ii, and the total refractive power of the lens is denoted by Ptotal , . is, where 11. Spectacle lens according to one of the above claims, wherein the material of the second lens (32) fixes the first lens (31) to the channel shell (13). 12 Spectacle lens according to one of the above claims, wherein the material of the second lens (32) is tinted.

13. Spectacle lens according to one of the above claims, wherein the second lens (32) is switchable between tinted and non-tinted.

14. Spectacle lens according to one of the above claims, wherein the second lens (32) has at least one active optic with adjustable refractive power.

15. Spectacle lens according to one of the above claims, wherein a liquid or a moldable material is used as the material for the second lens (32).

16. A display device comprising a holding device (2) which can be placed on the head of a user, an image generation module (5) which is fastened to the holding device (2) and which generates an image, and a spectacle lens (3) fastened to the holding device (2) according to one of the above claims, wherein the generated image is coupled into the first shell (13) via the entry section (12), guided in the first shell (13) by at least reflection to the deflection section (18), and deflected at the first deflection section (18) in order to exit from the spectacle lens (3) via the inner shell (25), so that the user can perceive it as a virtual image when the holding device (2) is placed on the head.

17. Display device according to claim 16, wherein the image generation module (5) generates the image with a first lateral chromatic aberration which compensates for a second lateral chromatic aberration generated by the spectacle lens (3) in the virtual image.

18. A method for producing a spectacle lens according to any one of claims 1 to 15, comprising the steps: A) producing the first lens (31) with the Fresnel-structured surface (33) and form-fitting filling of the Fresnel-structured surface (33) with the material of the second lens (32) in order to produce the Fresnel lens, B) Providing the channel shell (13), and C) mechanically connecting the Fresnel lens to the channel shell (13) to produce the spectacle lens (3, 4).

19. The method according to claim 18, wherein the following substeps are carried out in step A: A1 ) Producing at least two different types of the first lens (31) with different Fresnel-structured surfaces (33), A2) selecting a type of the first lens depending on a desired total refractive power of the inner shell (25) and a lens-eye distance of a user for whom the lens is intended, and A3) Selecting the refractive index of the second lens (32) in such a way that an adaptation to the desired total refractive power of the inner shell (25) and to the lens-eye distance is carried out.

20. The method according to claim 19, wherein in step A3 the refractive index of the second lens (32) is selected such that at least one of the interference edges (35) lies in a shadow area (43) which is not optically detectable by the user during the intended use of the spectacle lens (3).

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