Spectacle lens for imaging optics, imaging device and data glasses

Abstract

Spectacle lens (1, 31, 51) for an imaging optic for generating a virtual image from a source image displayed on an image transmitter (63), comprising: - an inner surface facing the eye (3, 33, 53) and an outer surface facing away from the eye (5, 35, 55), - a coupling section (7, 37, 57) for coupling an imaging beam path originating from the initial image between the inner surface (3, 33, 53) and the outer surface (5, 35, 55) of the spectacle lens (1, 31, 51) and - an outcoupling structure (9, 39, 65) present in the spectacle lens (1, 31, 51) for coupling the imaging beam path out of the spectacle lens (1, 31, 51) towards the eye, wherein the imaging beam path is guided to the outcoupling structure (9, 39, 65) by reflections between the inner surface (3, 33, 53) and the outer surface (5, 35, 55), wherein between the coupling section (7, 37, 57) and the coupling out structure (9, 39, 65) in the region of the inner surface (3, 33, 53) and / or in the region of the outer surface (5, 35, 55) there is at least one concavely curved reflection surface (R3, TR2) as seen from the interior of the spectacle lens (1, 31, 51), the curvature of which differs from a basic curvature of the inner surface (3, 33, 53) or the outer surface (5, 35, 55) of the spectacle lens (1, 31, 51), characterized by the fact that at least the reflection surface (TR3) at which the last reflection of the imaging beam path before the output coupling structure (39) takes place is designed as a concave curved reflection surface.

Description

[0001] The present invention relates to a spectacle lens for an imaging optics system for generating a virtual image from an output image displayed on an image generator. The invention also relates to an imaging optics system and data glasses.

[0002] Data glasses are a special type of head-mounted display. A common form of head-mounted display uses screens that are worn in front of the eyes and present the user with electronic images, such as computer-generated images or images captured by cameras. Such head-mounted displays are often bulky and do not allow direct perception of the surroundings. More recently, head-mounted displays have been developed that are capable of combining electronic images with the directly perceived image of the surroundings, thus presenting the user with an electronic image without preventing direct perception of the surroundings. Such head-mounted displays, referred to below as data glasses, enable the use of this technology in everyday life.

[0003] When combining electronic images with the directly perceived image of the environment, one essentially distinguishes the following principles on which the combination can be based: 1. Use of normal glasses with a beam combiner attached (e.g. beam splitter cube). 2. Direct coupling of the light from the side via a reflection on the inside of the lens, with the support of diffraction gratings, Fresnel elements or similar. 3. Guiding the light of the electronic image by means of total internal reflection in the lens and merging the beam path of the electronic image with the immediate image of the surroundings using an output coupling structure arranged in the lens to output the beam path of the electronic image from the lens toward the eye. A corresponding lens is described, for example, in DE 10 2014 118 490 A1.

[0004] DE 10 2013 214 700 A1 discloses a spectacle lens for an image-generating display device having a front side and a back side, a coupling-in section and a coupling-out section, wherein the generated image is coupled in via the coupling-in section and guided in the spectacle lens by total internal reflection to the coupling-out section and coupled out via the coupling-out section.

[0005] The first principle works very well visually, but has very little social acceptance, as the front beam combiner is very conspicuous and large. Furthermore, it makes the glasses front-heavy.

[0006] The second principle can only be realized anatomically if the distance between the glasses and the head is greatly increased, which is also unacceptable.

[0007] The more promising approaches therefore rely on the third principle, i.e., the light guidance within the lens. The outcoupling structure can be designed as a diffraction grating, a semi-transparent tilted mirror, or in the form of semi-transparent Fresnel elements. In the case of a diffraction grating, the beam path of the electronic image is coupled out of the lens via the first-order diffraction maximum, for example, while the observation light can pass through the outcoupling structure as unaffected as possible via the zero-order diffraction maximum.

[0008] However, the decoupling process gives rise to the fundamental problems described below, which depend in particular on the principle used.

[0009] When coupling out the beam path of the electronic image using a diffraction grating, gratings of the same frequency must be used for both the input and output of the beam path to prevent unreasonable spectrum spreading. The étendue of the imaging beam, which for the purposes of further explanations can be viewed as the product of the horizontal field of view and the horizontal extent of the eye box (the area of ​​the light tube in the imaging beam path in which the eye pupil can move without vignetting the image), is severely restricted in this case. This is because, on the one hand, the diffraction angle for blue light must be large enough to achieve total internal reflection in the glass, but, on the other hand, it must not exceed 90 degrees for red light.Added to this are the requirements for the horizontal field of view, which further exacerbates this constraint. Diffraction efficiency is also problematic, as a lot of light is lost due to the double diffraction, and homogeneous efficiency across the spectrum is hardly achievable.

[0010] When coupling out the optical path of the electronic image using an inclined mirror, the maximum tolerable lens thickness represents a hard limit. To achieve total internal reflection, the output mirror must have a minimum tilt angle. Since it must fit into a relatively thin lens for aesthetic reasons, it can only be relatively narrow, which means that the transmitted étendue is very small.

[0011] There are fewer disadvantages when coupling out the beam path of the electronic image using Fresnel elements, as there is no spectral dependence, and the Fresnel element does not need to be tilted relative to the inner or outer surface like the output mirror. Nevertheless, even when coupling out the beam path using Fresnel elements, an increase in the étendue is desirable.

[0012] It is therefore an object of the present invention to provide a spectacle lens for an imaging optic that enables greater value for the étendue. Furthermore, it is an object of the invention to provide an imaging optic and data glasses that enable greater value for the étendue.

[0013] The first object is achieved by a spectacle lens according to claim 1, the further object by an imaging device according to claim 11 or data glasses according to claim 14. The dependent claims contain advantageous embodiments of the invention.

[0014] A spectacle lens according to the invention for imaging optics for generating a virtual image from an output image displayed on an image generator comprises an inner surface facing the eye and an outer surface facing away from the eye, a coupling section for coupling an imaging beam path emanating from the output image between the inner surface and the outer surface of the spectacle lens, and an outcoupling structure present in the spectacle lens for coupling the imaging beam path out of the spectacle lens toward the eye. The imaging beam path is guided to the outcoupling structure by reflections between the inner surface and the outer surface.Between the coupling-in section and the coupling-out structure, in the region of the inner surface and / or the outer surface of the spectacle lens according to the invention, there is at least one reflection surface that is concavely curved as seen from the interior of the spectacle lens – and thus exerts a collecting effect on the imaging beam path – whose curvature differs from a basic curvature of the inner surface or the outer surface of the spectacle lens. The coupling-out structure is then preferably designed exclusively to deflect the beam, i.e., without a collecting or scattering effect.

[0015] The concavely curved reflection surface creates a converging effect, which can be used to increase the étendue. If the beam path through the lens is viewed backward—that is, from the eye to the coupling section, and thus opposite to the actual path—the converging effect of the reflection surface can focus the essentially collimated beam of rays from the eyebox onto the coupling-out structure toward the coupling section.This means that, on the one hand, due to the tapered beam cross-section, a smaller lateral extent is required for the reflection surfaces following in the direction of the coupling section. On the other hand, it can be achieved that the beam bundle can have a significantly smaller bundle cross-section in the region of the coupling section compared to a spectacle lens without a concavely curved reflection surface, which facilitates coupling into the spectacle lens. This can reduce the space required between the imager and the spectacle lens, and in the best case scenario, the previously used coupling device for coupling an imaging beam path emanating from the output image between the inner and outer surfaces of the spectacle lens can be dispensed with. In this case, the imager can be arranged directly at the coupling section or in the immediate vicinity of the coupling section.In both cases, the coupling takes place without the need for an intermediate coupling device.

[0016] In the spectacle lens according to the invention, at least the reflection surface at which the last reflection of the imaging beam path occurs before the outcoupling structure is designed as a concavely curved reflection surface. As a result, the reduction in the beam cross-section of the imaging beam path (viewed backwards, i.e., from the eye to the coupling section and thus opposite to the actual path) begins earlier, so that the lateral extent of the subsequent reflection surfaces can be kept as small as possible for a given field angle, or the largest possible field angle can be achieved for a given lateral extent of the subsequent reflection surfaces. Furthermore, the reduction in the beam cross-section in the region of the coupling section can be achieved with a long focal length, so that the curvature of the reflection surface can be kept as small as possible compared to the basic curvature of the inner surface or outer surface of the spectacle lens.

[0017] It is also advantageous if at least the reflection surface at which the penultimate reflection of the imaging beam path occurs before the outcoupling structure is designed as a concavely curved reflection surface, since this is then located on the same surface of the spectacle lens as the outcoupling structure, which offers manufacturing advantages because both can then be manufactured in common work steps. Furthermore, if the concavely curved reflection surface is located on the outer surface of the spectacle lens, which is usually also concavely curved when viewed from the inside of the spectacle lens, the deviation from the basic curvature of the spectacle lens need not be as pronounced as if the concavely curved reflection surface were located on the inner surface of the spectacle lens, which, when viewed from the inside of the spectacle lens, usually has a convex curvature.

[0018] Of course, it is also possible to design two or more of the reflection surfaces as concavely curved reflection surfaces, so that the collecting effect can be distributed over several reflection surfaces, which in turn allows a smaller deviation of the respective reflection surfaces from the basic curvatures of the lens surfaces in which they are formed.

[0019] In the spectacle lens according to the invention, the reflections of the imaging beam path can be based at least partially on total internal reflection at the inner surface and / or the outer surface. In one embodiment of the spectacle lens, the at least one concavely curved reflection surface is a surface section formed in the inner surface and / or the outer surface of the spectacle lens, which, as viewed from the interior of the spectacle lens, is concavely curved and whose curvature differs from the basic curvature of the inner surface or the outer surface of the spectacle lens.

[0020] In principle, total internal reflection may occur at the interface between the spectacle lens and the surrounding air. However, to protect the inner and outer surfaces or to achieve a specific optical effect or a desired aesthetic effect, the inner and / or outer surfaces may also be coated. In an advantageous embodiment of the spectacle lens with reflection based on total internal reflection, the spectacle lens therefore has a transparent base body with a first refractive index, in which the coupling section is located and into which the imaging beam path is coupled.This base body has an inner base body surface corresponding to the inner surface of the spectacle lens and an outer base body surface corresponding to the outer surface of the spectacle lens, and the at least one concavely curved surface section is formed in the inner base body surface and / or in the outer base body surface. In the region of the at least one concavely curved surface section, a first layer with a second refractive index is located on the inner base body surface and / or the outer base body surface. The second refractive index is selected in relation to the first refractive index such that total reflection of light rays from the imaging beam path occurs at the interface between the base body and the first layer.In other words, the second refractive index satisfies the condition n2 < n1 sin(θE), where θE represents an angle of incidence of the light rays of the imaging beam path emanating from the coupling section and incident on the respective reflection section, n1 represents the first refractive index, and n2 represents the second refractive index, and where the angle of incidence θ is selected such that at least 50% of the light rays of the imaging beam path, in particular at least 75% of the light rays of the imaging beam path, have an angle of incidence θ > θE. This ensures that at least 50% and in particular at least 75% of the light rays of the imaging beam path onto the reflection surface are reflected by total internal reflection. The higher the proportion of rays reflected by total internal reflection, the brighter the observable image appears for a given image brightness of the output image.

[0021] In the described advantageous embodiment of the spectacle lens with reflection based on total internal reflection, a second layer with a refractive index corresponding to the refractive index of the base material can be located above the first layer. In the context of the present description, corresponding refractive indices are understood to mean refractive indices that differ from one another by no more than 5‰, preferably no more than 1‰. This minimizes the optical effect of the reflective surface on transmitted ambient light rays. The second layer can in particular be a film with a refractive index corresponding to the refractive index of the base material or comprise such a film. The first layer and / or the second layer can be designed as an adhesive layer, which offers manufacturing advantages.In particular, the second layer can comprise an adhesive layer adjacent to the first layer and a film adjacent to the adhesive layer, with a refractive index corresponding to the base material. The use of a second layer formed as a film or comprising a film enables encapsulation of the spectacle lens to protect the first layer and the lens itself. It also allows the spectacle lens to be provided with additional near-surface functions. For example, an absorption or polarization film can be used to implement a sunglasses function to reduce the intensity of sunlight reaching the user's eye.

[0022] In order to increase the imaging quality of the spectacle lens, it is possible that in the spectacle lens according to the invention a free-form surface with properties that at least partially correct imaging errors is superimposed on the at least one concavely curved reflection surface.

[0023] An imaging device according to the invention for generating a virtual image comprises an image generator for displaying an output image and a spectacle lens according to the invention. The advantages to be achieved with the imaging device according to the invention arise from the statements regarding the spectacle lens according to the invention, which is why reference is made to the statements regarding the spectacle lens according to the invention. In particular, the imaging device according to the invention offers the possibility of arranging the image generator directly at the coupling section or directly in the vicinity of the coupling section, i.e. without the interposition of a coupling device. However, it is also possible for a coupling device to be present between the image generator and the coupling section for coupling an imaging beam path emanating from the output image between the inner surface and the outer surface of the spectacle lens. A coupling device can, for example,be designed as a prism with imaging effect.

[0024] Data glasses according to the invention comprise at least one imaging device according to the invention. As with the imaging device according to the invention, the advantages to be achieved with the data glasses according to the invention arise from the statements regarding the spectacle lens according to the invention, which is why reference is made to the statements regarding the spectacle lens according to the invention.

[0025] Further features, properties and advantages of the present invention will become apparent from the following description of embodiments with reference to the accompanying figures. Fig. Figure 1 illustrates the footprint overlap for a conventional spectacle lens with an inclined mirror for coupling out the imaging beam path. Fig. Figure 2 illustrates the footprint overlap for a conventional spectacle lens with a diffraction grating or a Fresnel element for coupling out the imaging beam path. Fig. 3 shows a conventional spectacle lens with an inclined, collecting mirror for coupling out the imaging beam path. Fig. Figure 4 illustrates the beam diameter of the imaging beam path in the region of the coupling section for a conventional spectacle lens with a Fresnel element for coupling out the imaging beam path. Fig. 5 shows a first embodiment of a spectacle lens according to the invention with a concavely curved reflection surface between the coupling section and the coupling-out structure. Fig. 6 shows a second embodiment of a spectacle lens according to the invention with a concavely curved reflection surface between the coupling section and the coupling-out structure. Fig. 7 shows a third embodiment of a spectacle lens according to the invention with a concavely curved reflection surface between the coupling section and the coupling-out structure. Fig. Figure 8 shows an example of a data glasses. Fig. 9 shows a spectacle lens with a prism as a coupling device

[0026] In order to explain the effect of the inventive design of the spectacle lens, reference will first be made to the Fig. 1 and Fig. 2 addresses the problem of the “footprint overlap”, which occurs in all three coupling variants (diffraction grating, tilted mirror and Fresnel elements), but is solved with varying degrees of success.

[0027] With reference to Fig. Figure 1 describes the problem of footprint overlap for a conventional spectacle lens 101 with an inclined output mirror for outputting the imaging beam path. It shows a section of the spectacle lens 101, which, in addition to the inner surface 103 and the outer surface 105 of the spectacle lens 101, also shows the output mirror 107, which is inclined by the tilt angle α to the outer surface 105. It also shows Fig. 1 the field of view angle δ of the horizontal field of view and the eye box 109. The eye box 109 is the three-dimensional area of ​​the light tube in the imaging beam path in which the eye pupil (in Fig. 1 not shown) without causing vignetting of the image. Since the distance of the eye relative to the smart glasses is essentially constant, the eye box can be reduced to a two-dimensional eye box that only takes into account the rotational movements of the eye. In this case, the eye box essentially corresponds to the exit pupil of the smart glasses at the location of the entrance pupil of the eye. The latter is usually determined by the eye's pupil.

[0028] Although data glasses are a system with an imaging beam path running from the imager to the eyebox 109, it is helpful to understand the "footprint overlap" by considering the beam path in the opposite direction, i.e., from the eyebox 109 to the imager. Therefore, the following explanations consider a light tube emanating from the eyebox 109, with the boundaries of the light tube being determined by the field of view angle δ of the beams propagating from each point of the eyebox toward the lens.

[0029] A beam emanating from the eyebox 109, which is reflected by the mirror 107 at the leftmost point A, strikes the outer surface 105 of the spectacle lens 101 at point B after reflection by the mirror 107 and total internal reflection at point 111 of the inner surface 103. This point B must no longer be located on the mirror 107, since otherwise the beam would be reflected a second time by the mirror 107 and thus lost for the image. To reduce the problem of "footprint overlap" in the present example, the output mirror 107 would have to be lengthened in order to increase the distance between points A and B, although the angle α by which the mirror 107 is tilted would have to remain unchanged. This would, however, increase the thickness of the spectacle lens.The calculation rule for the necessary lens thickness d for a given width b of the eye-box, a given distance I of the eye-box from the spectacle gas 101 and a given field of view angle δ is:. d=(b+l tanδ)tanα.

[0030] Fig. Figure 2 illustrates the problem of "footprint overlap" for a conventional ophthalmic lens 101 with a diffraction grating or a Fresnel element as the outcoupling structure 112 for outcoupling the imaging beam path. In this case, the calculation rule for the required ophthalmic lens thickness d for a given width b of the eyebox, a given distance I of the eyebox from the ophthalmic gas 101, and a given field of view angle δ is: d=(b+l tanδ)2tanα, where, in the case of the diffraction grating, the angle α represents the angle of deflection of the rays caused by diffraction. In the case of the Fresnel element, the angle α represents the tilt angle by which the Fresnel facets of the Fresnel element are inclined relative to the outer surface 105 of the spectacle lens 101. The above formulas contain some approximations, which, however, do not distort the basic relationship.

[0031] You can already see from Fig. 2 (which has the same scale as Fig. 1), that a significantly smaller lens thickness d or, in other words, a larger étendue is possible. As a rule of thumb, for the same lens thickness, with the diffraction grating or the Fresnel element, an étendue about twice as large is possible than with the inclined mirror made of Fig. 1.

[0032] A further problem affecting the étendue, in addition to the “footprint overlap,” is the increase in the bundle diameter in the imaging beam path with increasing distance from the outcoupling structure towards the incoupling section in the lens. This can be counteracted in the case of an inclined outcoupling mirror by providing the outcoupling mirror with a collecting effect (concave mirror). This is shown schematically in Fig. 3, which shows the spectacle lens 101, the inclined concave mirror 113 and the coupling section 115. In Fig. 3 it can be seen that due to the collecting effect of the output mirror the light passes well through the input coupling section 115 of the spectacle lens 101.

[0033] In the case of diffractive coupling, it is possible to put more diffractive power into the coupling grating in a similar way, but this is hardly manageable in terms of correction technology, since planar imaging gratings also have a spectrally dependent back focus and the other higher-order aberrations are also spectrally variable.

[0034] The Fresnel variant also poses problems in this regard, as it is necessary to ensure that beam areas emanating from the same imaging point are deflected approximately similarly by all Fresnel facets. Otherwise, image performance would be impaired. The pupil is segmented to a certain extent by the Fresnel illumination, and this must be counteracted by a non-imaging behavior of the Fresnel element. Thus, essentially, only a deflection analogous to a DMD chip is permitted. Fig. Figure 4 shows that, due to the non-collimating behavior of the Fresnel element 112, it is very difficult for the light to pass unhindered through the spectacle exit opening. Particularly in the case of a diffraction grating or a Fresnel element as the outcoupling structure 112, the increase in the beam diameter in the imaging beam path with increasing distance from the outcoupling structure represents a factor limiting the étendue.

[0035] Fig. Figure 5 shows a first embodiment of a spectacle lens 1 according to the invention for overcoming the problem mentioned. The spectacle lens 1 has an inner surface 3 facing the eye and an outer surface 5 facing away from the eye. At the edge of the spectacle lens, there is also a coupling section 7, via which an imaging beam path, which is generated by a light emitted by an image generator (in Fig. 5 not shown), is coupled into the spectacle lens 1 between the inner surface 3 and the outer surface 5. The spectacle lens 1 comprises a Fresnel element 9, which in the present exemplary embodiment serves as an outcoupling structure for coupling the imaging beam path out of the spectacle lens 1 in the direction of the eye (not shown). An imaging beam of the imaging beam path coupled into the spectacle lens 1 via the coupling section 7 is guided via reflections at reflection surfaces R1, R2, R3 and R4 to the Fresnel element 9, from which the beam is then coupled out of the spectacle lens 1 in the direction of the eye box.

[0036] In the Fig. 5, the imaging beam is guided to the Fresnel element 9 via four total reflections at the reflection surfaces R1, R2, R3 and R4. The total reflections of the reflection surfaces R1 and R3 occur on the outer surface 5 of the spectacle lens 1, whereas the total reflections of the reflection surfaces R2 and R4 occur on the inner surface 3 of the spectacle lens 1. The reflection surfaces R1, R2 and R4 have a curvature that corresponds to the basic curvature of the spectacle lens 1. The basic curvature of a spectacle lens is typically spherical, with the radii being approximately the same if no ametropia is to be corrected with the spectacle lens, or can be different if ametropia is to be corrected. The reflection surface R3, on the other hand, has a concave curvature as seen from the inside of the spectacle lens, which deviates from the basic curvature of the outer surface 5 of the spectacle lens 1.As a rule, the basic curvature of the outer surface 5 of the spectacle lens 1 is also concave when viewed from the inside of the lens, but the curvature of the reflection surface R3 deviates from the basic curvature in such a way that it has a greater concavity than the basic curvature. This additional concave curvature of the reflection surface R3 focuses a beam emanating from the eyebox 109, allowing a focus to be achieved in or near the coupling section 7. This allows the beam to be coupled into the spectacle lens even through a relatively narrow coupling section 7, allowing a large étendue to be achieved. Note that in the just-mentioned observation, the imaging beam path was again viewed backwards, i.e., from the eyebox 109 toward the image generator instead of from the image generator toward the eyebox 109.

[0037] Because in the spectacle lens according to the invention the collecting effect is not like in the inclined concave mirror Fig. 3 is caused by the outcoupling structure, when using a Fresnel structure 9 as the outcoupling structure, this can be used primarily for beam deflection. This allows the advantageous properties of the Fresnel structure 9 regarding footprint overlap to be combined with the advantages of the collecting effect of a concave mirror. Since the concavely curved reflection surface R3 does not need to be tilted relative to the outer surface 5, there is no restriction of the étendue, so that a large étendue, a large field of view angle δ, and a large eye box can be realized simultaneously. Furthermore, the coupling can take place via a relatively narrow coupling section, so that the provision of a special coupling structure can be dispensed with if necessary.

[0038] For comparison: If the étendue E is simplified to be the product of the field of view angle δ of the horizontal field of view and the horizontal width of the eyebox, then with a glass thickness of 4 mm in the case of the Fig. 2, the spectacle lens shown in the prior art has an étendue E of 4 mm x 7.5 degrees = 30 mm*degrees. Fig. In the variant of the spectacle lens according to the invention shown in Figure 5, however, an étendue of E = 8mm x 12grd = 96 mm*grd can be achieved.

[0039] A second embodiment of a spectacle lens according to the invention is shown in Fig. 6. The spectacle lens 31 of the second exemplary embodiment differs from that of the first exemplary embodiment in that it has a spectacle-lens-shaped base body 32, into whose outer surface 35 (hereinafter referred to as the base body outer surface) the Fresnel structure 39 and the concave reflection surface R3 are embossed. A two-layer coating 41 is applied to the base body outer surface 35, wherein the first layer 43, directly adjacent to the reflection surface R3 and the Fresnel structure 39, has a lower refractive index than the material of the base body 32, and the second, outer layer 45 has a refractive index adapted to the refractive index of the material of the base body 32. The adaptation of the refractive index of the outer layer 45 is selected such that, in the present exemplary embodiment, it differs from the refractive index of the base body material by no more than 1 ‰.Depending on the application, a somewhat larger difference in refractive index may be permitted. In any case, however, the refractive index of the outer layer 45 should not differ by more than 5 ‰ from the refractive index of the base body material. On the outside, the outer layer 45 has a radius of curvature suitable for the outer surface of the coated spectacle lens 31, which essentially corresponds to the basic curvature of the base body 32. The coating 41 can prevent the concave reflection surface R3 from negatively influencing the ambient light passing through it. The inner layer 43 with the low refractive index ensures that total internal reflection takes place at the interface between the base body 32 and the coating 41 in the region of the reflection surface R3 and in the region of the Fresnel facets.

[0040] In order for total reflection to occur at the interface between the base body 32 and the inner layer 43 of the coating 41, the angles of incidence θ E of the rays of the imaging beam path relative to the surface normal of a surface element at which the total reflection is to take place, is greater than the critical angle θ G for the occurrence of total reflection. The critical angle is determined by the ratio of the first refractive index n1, i.e. the refractive index of the material of the base body 32, to the second refractive index n2, i.e. the refractive index of the inner layer 43 of the coating 41, and can be calculated from the equation θG=arcsin(n2 / n1) For a given angle of incidence θ Eof the rays of the imaging beam path onto the reflective surface element, which results from the design of the base body 32 and the coupling of the imaging beam path into the base body 32 through the coupling section 37, and a given refractive index n1 of the material of the base body 32, the refractive index n2 required for the occurrence of total reflection at the interface of the base body 32 to the inner layer 43 of the coating 41 can be determined. Total reflection occurs when the inequality n2 <n1 sin(θE) is satisfied. Since sin(θ E ) is always less than or equal to 1, the second refractive index n2 must be smaller than the first refractive index n1. How much smaller than n1 depends on the angle of incidence θ E on the surface element - and thus on the design of the base body 32 and the coupling of the imaging beam path into the base body 32.

[0041] Although the coating 41 only needs to be present in the area of ​​the Fresnel structure 39 and the concave reflection surface R3, it is advantageous from a manufacturing point of view if the coating 41 is applied as in the Fig. 6 is applied to the entire outer surface 35 of the base body.

[0042] Within the scope of the present invention, several of the reflection surfaces can also be designed as concave reflection surfaces and thus have a collecting effect. The concave reflection surfaces can be arranged on both the inner surface of the base body and the outer surface of the base body. A corresponding embodiment is described in Fig. 7. The figure shows a spectacle lens 51 comprising a base body 52 with an inner surface 53 facing the user's eye and an outer surface 55 facing away from the user's eye. Furthermore, the spectacle lens 51 comprises coatings 59, 61 applied to the inner surface 53 and the outer surface 55 of the base body.

[0043] The base body 52 is provided at its edge with a coupling section 57. Via the coupling section 57, a beam of an imaging beam path emanating from an image generator 63 is coupled into the base body 52 between the base body inner surface 53 and the base body outer surface 55. In the present exemplary embodiment, the imaging beam path in the base body 52 is guided via three reflection surfaces TR1, TR2, and TR3, at which total reflection of the imaging beam occurs, to an outcoupling structure in the form of a Fresnel element 65, from which the imaging beam path is coupled out of the spectacle lens 51 in the direction of the user's eye.

[0044] The reflection surface TR1 and the reflection surface TR3 are formed in the inner surface 53 of the base body 52, whereas the reflection surface TR2 and the Fresnel structure 65 are formed in the outer surface 55 of the base body 52. ​​If the base body 52 is injection-molded from a plastic, for example, the reflection surfaces TR1, TR2, and TR3 and the Fresnel structure 65 can be embossed into the respective base body surface, for example, using a suitable injection mold.

[0045] In the Fig. In the embodiment shown in Figure 7, all three reflection surfaces TR1, TR2 and TR3 have a concave curvature, so that they have a collecting effect.

[0046] The coatings 59, 61 applied to the base body inner surface 53 and the base body outer surface 55 are each composed of several layers. An adhesive layer 67 with a low refractive index is applied directly adjacent to the base body inner surface 53 and the base body outer surface 55, respectively. The refractive index of the adhesive layer 67 is selected such that total reflection of the imaging beam path occurs at the interface between the base body inner surface 53 and the adhesive layer 67, or between the base body outer surface 55 and the adhesive layer 67. The criteria that the refractive index of the adhesive layer 67 must meet are derived from the above-described inequality 2.

[0047] In the present embodiment, the facets 69 of the Fresnel structure 65 are partially mirrored, so that the coupling out does not occur by total internal reflection. Therefore, in the present embodiment, the adhesive layer 67 with the low refractive index is not applied over the Fresnel structure 65.

[0048] Above the adhesive layer 67 with the low refractive index, there is a further adhesive layer 71 on both the base body inner surface 53 and the base body outer surface 55. This adhesive layer has a refractive index that is matched to the refractive index of the base body 52 such that the two refractive indices differ from each other by no more than 5‰ and preferably by no more than 1‰. This refractive index-matched adhesive layer 71 is located over the entire low-refractive index adhesive layer. Furthermore, the refractive index-matched adhesive layer 71 is also applied to the Fresnel structure 65.

[0049] In the present embodiment, a protective film 73 is located above the refractive index-matched adhesive layer 71, the refractive index of which is also matched to the refractive index of the base body 52. ​​The refractive index of the protective film 73 is also selected with respect to the refractive index of the base body 52 such that the two refractive indices differ from each other by no more than 5‰, preferably by no more than 1‰. The radii of curvature of the surfaces of the protective films 73 forming the outer surface of the spectacle lens and the inner surface of the spectacle lens each correspond to the basic curvature of the spectacle lens 51, which corresponds to the basic curvature of the base body 52.

[0050] By applying one of several refractive index-matched layers or films to the adhesive layer 67 with a low refractive index or the Fresnel structure 65, an influence of the ambient light perceptible to the user when passing through the Fresnel structure 65 or the reflection surfaces TR1, TR2 and TR3 can be avoided.

[0051] In addition to the protective function, the film 73 used in the present embodiment can have additional functions. For example, it can be equipped with an absorption or polarization function, so that the spectacle lens can be used as a lens for sunglasses.

[0052] In the example just described, a base body was used that was manufactured from an organic glass by means of an injection molding process. However, the base body can also be made from a mineral glass. In contrast to the Fig. In the exemplary embodiment shown in Figure 7, it is possible to provide only the reflection surface TR2 in the outer surface 55 of the base body with a concave effect. The curvatures of the reflection surfaces TR1 and TR3 then do not deviate from the basic curvature of the base body 52. ​​Since in this case there is no collecting effect of the reflection surfaces TR1 and TR3 in the area of ​​the inner surface 53 of the base body, the reflection surfaces TR1 and TR3 do not have a negative effect on ambient light passing through the spectacle lens 51, so that the coating system on the inner surface of the base body can be dispensed with if the reflection surfaces TR1 and TR3 are not concave. Of course, it is also possible to provide only the reflection surfaces TR1 and TR3 on the inner surface of the base body with a collecting effect. In this case, the coating system 59 would be present on the inner surface 53 of the base body.Since the reflection surface TR2 in the outer surface 55 of the base body then has no collecting effect, the coating system 61 on the outer surface 55 of the base body is not required. Only the Fresnel structure 65 is then filled with a material with a refractive index match to prevent any negative influence of ambient light passing through the Fresnel structure 65.

[0053] In the case of Fig. In the embodiment described in Figure 7, it is also possible to additionally overlay one or more of the reflection surfaces TR1, TR2 and TR3 with a free-form surface, so that in addition to the collecting effect, an aberration-reducing effect of the corresponding reflection surface can also be achieved.

[0054] The following describes a pair of data glasses with a spectacle lens according to the invention. The spectacle lens is part of an imaging optics system for generating a virtual image from an output image displayed on an image generator. A corresponding pair of data glasses 201 is shown in Fig. 8 shown.

[0055] The data glasses 201 comprise two lenses 203, 205 according to the invention, which are held by a frame 207 with two temples 209, 211. The lenses 203, 205 can be designed as described in the exemplary embodiments. An image generator, which can be designed as a liquid crystal display (LCD or LCoS display, LCoS: Liquid Crystal on Silicon), a light-emitting diode-based display (LED display), an organic light-emitting diode-based display (OLED display), etc., is located in the temple 209, 211 or between the temple 209, 211 and the respective lens 203, 205, for example, adjacent to the coupling section of the respective lens. A coupling device can be arranged between the imager and the spectacle lens as part of the imaging optics, which supports the coupling of an imaging beam path emanating from the imager into the spectacle lens via the coupling section.The coupling device can, for example, be designed as a prism with an entrance surface, a first mirror surface, and a second mirror surface, and can be made of glass or transparent plastic, with the entrance surface and the mirror surfaces being formed by surfaces of the prism. Such a spectacle lens 91 with a prism 93 as the coupling device is shown in . Fig. 9. Of the prism 93, Fig. 9 the entrance surface 75 and the reflection surfaces 97, 99 can be seen.

[0056] The present invention has been described in detail using exemplary embodiments for explanatory purposes. However, a person skilled in the art will recognize that the invention is not limited to the design of the exemplary embodiments. In particular, in all exemplary embodiments, any number of the reflection surfaces can be provided with a collecting effect. Likewise, in all exemplary embodiments, it is possible to overlay any number of the reflection surfaces with free-form surfaces to correct aberrations. Furthermore, the light guidance in the spectacle lens does not necessarily have to be achieved by means of total reflection. Light guidance using mirrored or partially mirrored surfaces is fundamentally also possible. The coatings mentioned in the exemplary embodiments can also have more than the described layers or fewer than the described layers. For example, in the embodiments with reference to Fig.In the exemplary embodiment described in Figure 7, the refractive index-matched adhesive layer can be omitted if the outcoupling via the Fresnel structure occurs by means of total internal reflection, the adhesive layer with a low refractive index is also applied over the Fresnel structure, and the adhesive layer is suitable as an adhesive for fixing the protective film. Likewise, the number of total internal reflections used between the incoupling section and the outcoupling structure can be more than 4 or less than 3. Finally, it should be noted that although the outcoupling structure in the exemplary embodiments is a Fresnel structure, the present invention can in principle also be used for spectacle lenses with a diffractive outcoupling structure. It is also not excluded that the present invention is used in conjunction with an inclined mirror as the outcoupling structure.The present invention is therefore intended to be limited only by the appended claims.

Claims

[1] Spectacle lens (1, 31, 51) for an imaging optics for generating a virtual image from an output image displayed on an image generator (63), comprising: - an inner surface (3, 33, 53) facing the eye and an outer surface (5, 35, 55) facing away from the eye, - a coupling section (7, 37, 57) for coupling an imaging beam path emanating from the output image between the inner surface (3, 33, 53) and the outer surface (5, 35, 55) of the spectacle lens (1, 31, 51) and - a coupling-out structure (9, 39, 65) present in the spectacle lens (1, 31, 51) for coupling the imaging beam path out of the spectacle lens (1, 31, 51) in the direction of the eye, wherein the imaging beam path is guided to the coupling-out structure (9, 39, 65) by reflections between the inner surface (3, 33, 53) and the outer surface (5, 35, 55), wherein between the coupling section (7, 37, 57) and the coupling-out structure (9, 39, 65) in the region of the inner surface (3, 33, 53) and / or in the region of the outer surface (5, 35, 55) there is at least one concavely curved reflection surface (R3, TR2) as seen from the interior of the spectacle lens (1, 31, 51), the curvature of which differs from a basic curvature of the inner surface (3, 33, 53) or the outer surface (5, 35, 55) of the spectacle lens (1, 31, 51), characterized by , that at least that reflection surface (TR3) at which the last reflection of the imaging beam path occurs before the coupling-out structure (39) is designed as a concavely curved reflection surface. [2] Spectacle lens (1, 31, 51) according to claim 1, characterized by that the coupling-out structure (9, 39, 64) is designed exclusively to deflect the beam. [3] Spectacle lens (1, 31, 51) according to one of the preceding claims, characterized bythat at least that reflection surface (R3, TR2) at which the penultimate reflection of the imaging beam path takes place before the coupling-out structure (9, 39, 65) is designed as a concavely curved reflection surface. [4] Spectacle lens (1, 31, 51) according to one of the preceding claims, characterized by in that the reflections of the imaging beam path are based on total reflection on the inner surface (3, 33, 53) and / or the outer surface (5, 35, 55) and the at least one concavely curved reflection surface (R1, R2, R3, R4, TR1, TR2, TR3) is a surface section formed in the inner surface (3, 33, 53) and / or the outer surface (5, 35, 55) of the spectacle lens (1, 31, 51), which, viewed from the interior of the spectacle lens (1, 31, 51), is concavely curved and the curvature of which differs from the basic curvature of the inner surface (3, 33, 53) or the outer surface (5, 35, 55) of the spectacle lens (1, 31, 51). [5] Spectacle lens (31, 51) according to claim 4, characterized by , that - the spectacle lens (31, 51) has a transparent base body (32, 52) with a first refractive index, into which the imaging beam path is coupled, wherein the base body (32, 52) has an inner base body surface (33, 53) corresponding to the inner surface (13) of the spectacle lens (31, 51) and an outer base body surface (35, 55) corresponding to the outer surface of the spectacle lens (31, 51), and the at least one concavely curved surface section is formed in the inner base body surface (33, 53) and / or in the outer base body surface (35, 55), - in the region of the at least one concavely curved surface section on the base body inner surface (33, 53) and / or the base body outer surface (35, 55) there is a first layer (43, 67) with a second refractive index which is selected in relation to the first refractive index such that a total reflection of light rays of the imaging beam path occurs at the interface between the base body (32, 52) and the first layer (43, 67). [6] Spectacle lens (31, 51) according to claim 5, characterized by that above the first layer (43, 67) there is at least one second layer (45, 71, 73) with a refractive index corresponding to the refractive index of the material of the base body (32, 52). [7] Spectacle lens (51) according to claim 6, characterized by that the second layer is or comprises a film (73) with a refractive index corresponding to the refractive index of the material of the base body (32, 52). [8] Spectacle lens (51) according to one of claims 5 to 7, characterized by that the first layer is or comprises an adhesive layer (67) and / or the second layer is or comprises an adhesive layer (71). [9] Spectacle lens (51) according to claim 7 and claim 8, characterized by that the second layer comprises an adhesive layer (71) adjacent to the first layer (67) and a film (73) adjacent to the adhesive layer (71) with a refractive index corresponding to the refractive index of the material of the base body (32, 52). [10] Spectacle lens (1, 31, 51) according to one of the preceding claims, characterized by that a free-form surface with aberration-correcting properties is superimposed on the at least one concavely curved reflection surface (R1, R2, R3, R4, TR1, TR2, TR3). [11] Imaging device for generating a virtual image with an image generator (63) for displaying an output image and a spectacle lens (51) according to one of the preceding claims. [12] Imaging device according to claim 11, characterized by that the image generator (63) is arranged directly on the coupling section (57) or directly in the vicinity of the coupling section (57). [13] Imaging device according to claim 11, characterized by that between the image generator (63) and the coupling section (57) there is a coupling device (93) for coupling an imaging beam path emanating from the output image between the inner surface and the outer surface of the spectacle lens (1, 31, 51). [14] Data glasses with at least one imaging device according to one of claims 11 to 13.

Images