LENS FOR A DISPLAY DEVICE THAT CAN BE PLACED ON THE HEAD OF A USER AND PRODUCES AN IMAGE

Description

[0001] The present invention relates to a spectacle lens for a display device that can be placed on the head of a user and generates an image according to the preamble of claim 1, a display device with such a spectacle lens and a method for producing such a spectacle lens.

[0002] Such spectacle lenses are known, for example, from WO 2015 / 150269 A1 and have a front side, a back side, a coupling section, a deflection section spaced from the coupling section, an exit section in the back side and a light guide channel which guides light bundles from pixels of the generated image, which are coupled into the spectacle lens via the coupling section of the spectacle lens, in the spectacle lens to the deflection section, from which they are deflected in the direction of the exit section and then coupled out of the spectacle lens through the exit section.

[0003] Such a spectacle lens can be part of the imaging optics of a display device that can be placed on a user's head and generates an image. The imaging optics project the generated image when the display device is in place, allowing the user to perceive it as a virtual image. Thus, the spectacle lens contributes to the desired functionality of projecting the generated image into the user's field of vision.

[0004] Based on this, it is the object of the invention to further develop a spectacle lens of the type mentioned at the outset in such a way that it basically provides the function of image reflection for as many different users as possible.

[0005] Furthermore, a display device with such a spectacle lens and a manufacturing method for such a spectacle lens are to be provided.

[0006] The invention is defined in claim 1.

[0007] By designing the spectacle lens as a progressive lens and arranging the exit section outside the distance range and outside the near range (as seen in a top view of the back of the spectacle lens), the spectacle lens according to the invention can be provided for users who require progressive lenses. Since the exit section is arranged outside the distance range and outside the near range, the area of ​​the progressive lens is advantageously utilized which, due to the system's inherent aberrations (due to the so-called Minkwitz theorem) during normal use of the progressive lens, exhibits such high aberrations that these areas of the progressive lens are not used, or only used to a limited extent, by the user when looking through the progressive lens.

[0008] In the progressive lens according to the invention, the curvature (or the curvature profile) of the exit section differs from the curvature (or the curvature profile) of an intermediate region of the back side between the exit section and the near area in such a way that the refractive error correction is worse when viewing the surroundings through the exit section than when viewing the surroundings through the intermediate area.

[0009] The transition from the exit section to the surrounding area of ​​the rear side can be designed as a continuous and differentiable surface section. In particular, the entire rear side can be designed as a continuous and differentiable surface.

[0010] Furthermore, in the spectacle lens according to the invention, the front side can be curved and the back side can be curved.

[0011] The guidance of the light beams in the spectacle lens from the coupling section to the deflection section can be achieved by reflections (e.g. total internal reflections).

[0012] In the spectacle lens according to the invention, the back side can be designed as a free-form surface which effects the desired refractive error correction.

[0013] Furthermore, the exit section can be spherically or aspherically curved. In particular, the exit section can be designed as a freeform surface.

[0014] The front side of the lens can be spherically curved.

[0015] The spectacle lens according to the invention can also be designed such that the front side is designed as a freeform surface for correcting ametropia, and the back side is spherically curved. This design provides the advantage that the light beams are coupled out through the back side, and in particular through the exit section in the back, independently of the effect of the progressive lens, since the ametropia correction is achieved by the front side designed as a freeform surface. Furthermore, it is possible to design both the front side and the back side as freeform surfaces, which together achieve the desired ametropia correction.

[0016] In the spectacle lens according to the invention, the astigmatism in the exit section can be at least 1 diopter and in particular at least 2 diopters.

[0017] Furthermore, in the spectacle lens according to the invention, the astigmatism in the near field cannot be greater than 1 dioptre and in particular not greater than 0.5 dioptres.

[0018] In the spectacle lens according to the invention, the distance and near areas, viewed from the back of the lens, can be T-shaped together. In particular, the distance area can be located above the near area. The exit section can be arranged to the right or left of the near area.

[0019] The lens can be designed as a single-layer, double-layer, or multi-layer lens. To guide the light beams within the lens, reflections can occur on the front and / or back. One or more reflective or partially reflective layers are provided within the lens and at the light guide channel to guide the light beams. It is also possible to provide one or more reflective or partially reflective layers on the front and / or back to guide the light beams.

[0020] The deflection section can have a reflective or a partially reflective deflection surface. Furthermore, it is possible for the deflection section to have several reflective or partially reflective deflection surfaces arranged next to one another. The deflection section can be designed to purely deflect the beam. However, it is also possible for the deflection section to additionally have an imaging property. This can be achieved by a corresponding arrangement of the deflection surfaces (which can also be referred to as facets). Additionally or alternatively, this can be achieved by a curvature of the deflection surfaces or of the individual deflection surfaces.

[0021] The reflective or partially reflective facets can be arranged offset from one another in the manner of a zigzag line or a sawtooth line.

[0022] The deflection surface(s) preferably extend only over a portion of the lens, rather than the entire thickness (extension from the front to the back). In particular, the deflection surface(s) can be designed as buried deflection surface(s) that extend just to the front or not to the front. Any depressions created by the deflection surfaces can be designed to create a continuous front surface.

[0023] Furthermore, 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 an imaging optic that is fastened to the holding device and has a spectacle lens according to the invention and that images the generated image in the state of the holding device exposed to the user's head in such a way that the user can perceive it as a virtual image.

[0024] The imaging optics can comprise the spectacle lens as the sole optical element. However, it is also possible for the imaging optics to comprise at least one further optical element in addition to the spectacle lens. The at least one further optical element can be spaced apart from the spectacle lens or connected to it. Furthermore, it is possible for the at least one further optical element to be formed integrally with the spectacle lens.

[0025] The display device may include a control unit that controls the image generation module.

[0026] The image generation module can, in particular, comprise a planar imager, such as an LCD module, an LCoS module, an OLED module, or a tilting mirror array. The imager can comprise a plurality of pixels, which can be arranged, for example, in rows and columns. The imager can be self-luminous or non-self-luminous.

[0027] The image generation module can in particular be designed to generate a monochromatic or a multi-colored image.

[0028] The display device according to the invention may comprise further elements known to the person skilled in the art which are necessary for the operation of the display device.

[0029] Furthermore, a method for producing a spectacle lens according to the invention is provided, in which various refractive error ranges, each determined by a range of aberrations to be corrected, are defined, a curvature of the exit section is calculated for each refractive error range and this exit section is assigned to the refractive error range, the refractive error range is determined in which the aberration value of the spectacle lens to be produced falls, the curvature of the back of the spectacle lens to be produced is calculated such that the exit section assigned to the determined refractive error range is selected and its curvature is retained and not changed when calculating the curvature of the back, and the spectacle lens is produced based on the calculated curvature of the back.

[0030] The aberration to be corrected could, for example, be spherical aberration. The refractive error ranges can then extend over ± 2 diopters, ± 1 diopter, or ± 0.5 diopters. This makes it possible, for example, to divide refractive errors from the range of -10 to +10 diopters into 5, 10, or 20 refractive error ranges and to calculate exactly one curvature for the exit section for each of these refractive error ranges and assign it to this refractive error range. This means that only 5, 10, or 20 curvatures need to be calculated for the exit section. This can be done once, and then the calculated curvatures for the exit section can be used to individually design a spectacle lens. This significantly simplifies the production of a progressive lens for a user.It has been shown that this approach can achieve excellent imaging properties for the representation of the virtual image.

[0031] The aberration to be corrected can be a single aberration (such as spherical aberration) or several different aberrations.

[0032] The method according to the invention for producing a spectacle lens can be further developed so that the spectacle lens according to the invention (including its further developments) can be produced.

[0033] 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.

[0034] The invention is explained in more detail below, for example, with reference to the accompanying drawings, which also disclose essential features of the invention. They show: Fig. 1 is a schematic perspective view of an embodiment of the display device according to the invention; Fig. 2 is an enlarged partial sectional view of the first spectacle lens including a schematic representation of the image generation module; Fig. 3 is a schematic sectional view of the first spectacle lens; Fig. 4 is a plan view of the back 15 of the first spectacle lens; Fig. 5 is a plan view of the back of a further embodiment of the first spectacle lens with level lines for spherical aberration; Fig. 6 is a plan view of the back of the first spectacle lens 3 according to Fig. 5 with astigmatism level lines; Fig. 7 a plan view of the back of a conventional first spectacle lens in the same way as in Fig. 5; Fig. 8 a plan view of the back of a conventional spectacle lens in the same way as in Fig. 6 , and Figs. 9 to 11 enlarged partial sectional views of further embodiments of a first spectacle lens according to the invention including a schematic representation of the image generation module.

[0035] At the Fig. 1 In the embodiment shown, 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 holding device 2 with the spectacle lenses 3 and 4 is designed as progressive lenses for correcting ametropia, wherein a virtual image can be projected into the user's field of vision via the first spectacle lens 3, as described below.

[0036] For this purpose, the display device 1 comprises an image generation module 5, which can be arranged in the area of ​​the right temple 2, as shown in Fig. 1 is shown schematically. The image generation module 5 can be a planar image generation element 6 ( Fig. 2 ), such as an OLED, a CMOS or an LCoS chip or a tilting mirror matrix, with a large number of pixels arranged in columns and rows, for example.

[0037] The spectacle lenses 3 and 4, and in particular the first spectacle lens 3, are described only by way of example together with the display device 1 according to the invention. The spectacle lenses 3, 4, or at least the first spectacle lens 3, are each individually designed as a spectacle lens 3, 4 according to the invention.

[0038] As best seen from the enlarged schematic partial sectional view in Fig. 2As can be seen, the display device 1 has an imaging optics 7, which contains an optical element 8 arranged between the image generating element 6 or the image generator 6 and the first spectacle lens 3. Furthermore, the first spectacle lens 3 itself also serves as part of the imaging optics 7.

[0039] A light beam 9 can emanate from each pixel of the imager 6. By appropriately controlling the pixels of the imager 6 by means of a control unit 10, which can be part of the image generation module 5, the desired image can be generated. Fig. 2 The beam path of a light beam is shown as a representative of the light bundles 9, so that the light beam 9 is also referred to below.

[0040] The light beam 9 emanating from the imager 6 passes through the optical element 8 and enters the first spectacle lens 3 via a coupling section 11 (here, the end face of the first spectacle lens 3) and is guided therein along a light guide channel 12 to a deflection section 13. The deflection section 13 here has several partially reflective deflection surfaces 14 (which can also be referred to as partially reflective facets) arranged side by side, at which the light beams 9 are reflected toward a rear side 15 of the first spectacle lens 3, so that the light beams 9 exit the first spectacle lens 3 via an exit section 16 of the rear side 15. Thus, a user, when wearing the display device 1 according to the invention on their head as intended, can perceive the image generated by the imager 6 as a virtual image when looking at the deflection section 13. Fig. 2For clarity, the pivot point 17 of the user's eye and the eyebox 18 or exit pupil 18 of the imaging optics 7 are shown. The eyebox 18 is the area in which the user's eye can move and can still perceive the generated image as a virtual image.

[0041] Although in the described embodiment the coupling is carried out into the front side of the first spectacle lens 3 and thus the coupling section 11 is formed on the front side of the first spectacle lens, it is also possible to carry out a coupling via the back side 15 of the first spectacle lens 3.

[0042] As shown in the schematic diagram in Fig. 2As shown, the rear side 15 and a front side 19 of the first spectacle lens 3 are each curved. The first spectacle lens 3 is furthermore formed with two shells and comprises an outer shell 20 and an inner shell 21. The side of the outer shell 20 facing away from the inner shell 21 forms the curved front side 19 of the first spectacle lens 3, and the side of the inner shell 21 facing away from the outer shell 20 forms the rear side 15 of the first spectacle lens 3.

[0043] To form the light guide channel 12, a first reflective surface 22 is formed between the outer and inner shells 20, 21, which extends from the coupling section 11 to the deflection section 13. Furthermore, a second reflective surface 23 can be formed on the front side 19, opposite the first reflective surface 22, which in turn extends from the coupling section 11 to the deflection section 13. The two reflective surfaces 22 and 23 are preferably partially reflective. The light beams coupled in via the coupling section 11 can thus be guided in the light guide channel 12 by reflections on the reflective surfaces 22 and 23 from the coupling section 11 to the deflection section 13. The second reflective surface 23 can also be omitted.In this case, a total internal reflection for the light beams 9 is preferably effected on the front side 19 in the region of the light guide channel 12 in order to ensure the desired guidance of the light beams in the light guide channel 12.

[0044] In Fig. 3 A schematic sectional view in the zx plane of the first spectacle lens 3 is shown, which is designed as a progressive lens. The front side 19 is spherically curved, and the rear side 15 has an aspherical curvature with increasing curvature in the x-direction (and thus with decreasing radii of curvature r1, r2, r3, r4, r5 in the x-direction), so that the upper area is corrected for distance vision and the lower area for near vision. For clarity, the curvature profile with a constant radius of curvature r1 is shown in dashed lines and is designated by the reference numeral 15'.

[0045] The radius of curvature r1 thus denotes the curvature for distance vision. The radius of curvature r5 denotes the radius of curvature for near vision, and the radii of curvature r2 - r4 are the radii of curvature in the transition zone between distance and near vision. Thus, the first lens exhibits a smooth (i.e., continuous) diopter transition between the (upper) distance portion and the (lower) near portion. The necessary higher curvature of the first lens 3 in the lower portion leads to astigmatic errors in the transition zone in the lateral field of view. This effect is often referred to as the Minkwitz theorem.

[0046] This astigmatic error is shown in the schematic plan view of the back 15 in Fig. 4They are schematically represented as contour lines for equal astigmatic errors. Lines L1, L2, L3, L4, and L5 correspond to an astigmatic error of 0, 1, 2, 3, and 4 diopters, respectively. Thus, for example, the astigmatic error at line L3 is 2 diopters. The astigmatic error here is understood to be the difference between the refractive power in the y-direction and the refractive power in the x-direction.

[0047] Thus, the progressive lens 3 has an upper distance area F for distance vision and a lower near area N for near vision, whereby the near area N has a significantly smaller extent in the y-direction than the distance area F due to the unavoidable astigmatic error in the lateral field of view (Minkwitz theorem). The distance area F and the near area N thus together form a T-shape when viewed from above onto the back 15.

[0048] The first spectacle lens 3 is now designed so that the exit section 16 (in the illustration of Fig. 4 seen) is located at the bottom right, so that a user with the display device attached relative to the straight view G ( Fig. 2) has to look down to the right in order to be able to perceive the generated image as a virtual image. In order to ensure that the image is displayed with as little as possible astigmatic errors (which occur precisely in this area of ​​the progressive lens 3 on the aspherical rear side 15), the curvature of the rear side 15 in the exit section 16 is different or distinct from the curvature of the area surrounding the rear side 15 immediately adjacent to the exit section 16. In particular, the entire imaging optics 7 and therefore also the curvature of the exit section 16 are designed such that the image is as distortion-free as possible. This can, for example, lead to a poorer visual correction when viewing the surroundings through the exit section 16, if no image is generated and is displayed as a virtual image, compared to the case in which there would be no special adaptation of the curvature of the exit section 16.It can also be said that the refractive error correction is worse when viewing the surroundings through the exit section 16 than when viewing the surroundings through a section 24 that lies between the exit section 16 and the near field N.

[0049] In Fig. 5 The back of an embodiment of the progressive lens 3 according to the invention is shown in plan view, with the refractive power (spherical power) in diopters indicated by level lines. The dimensions in the x- and y-directions are given in millimeters. The progressive lens is designed for a user who requires no correction for distance vision and a correction of +2 diopters for near vision. Fig. 6 is in the same way as in Fig. 5 a plan view of the back 15 of the lens of Fig. 5 shown, where in Fig. 6 Level lines for the astigmatism of the progressive lens 3 are shown. As can be seen from the illustrations in Figs. 5 and 6As can be seen, the exit section 16 is located outside the distance range F and outside the near range N in the lower lateral (here right) field of view. In this range, there is a low refractive power (here a range of 0.75 diopters) and a high astigmatism (here in the range of ≥ 2). However, the curvature of the exit section 16 is designed to enable a good and thus as error-free as possible perception of the generated image as a virtual image.

[0050] In Figs. 7 and 8 is a conventional progressive lens 3' in the same way as in Figs. 5 and 6 shown. Thus, in Fig. 7 in plan view of the back 15" the refractive power (spherical effect) in diopters and in Fig. 8 The astigmatism is shown for a lens that is supposed to have no correction in the distance range F and a correction of + 2 diopters in the near range N. As a comparison of the Figures 7 and 8 with the Figures 5 and 6shows, in the conventional spectacle lens 3' there is less astigmatism in the lower right field of view than in the comparable area (exit section 16) of the spectacle lens 3 according to the invention according to Fig. 6 This shows that the spectacle lens 3 according to the invention has poorer properties for viewing in the lower right field of view than a conventional progressive lens 3' for the same user with the same conditions (i.e., here, a distance range F without a refractive error correction and a near range N with a refractive error correction of +2 diopters). However, since this lower right field of view is not usable by the user due to the nature of the progressive lens, this deterioration in viewing is not a disadvantage. On the contrary, this actually unused area of ​​the progressive lens 3 is now advantageously used to generate the desired virtual image.

[0051] The curvature of the exit section 16 can be spherical or aspherical, for example. Preferably, the transition between the exit section 16 and the immediately adjacent region of the rear side 15 (e.g., section 24) is designed to be continuous and differentiable. In particular, the entire rear side 15 is preferably designed as a continuous and differentiable surface.

[0052] In the embodiment described here, the inner shell 21 or the curvature of the back 15 serves as a correction surface that provides the desired progressive lens functionality.

[0053] The first lens 3 can also be designed with three layers, as in Fig. 9 is shown schematically. The representation of Fig. 9 corresponds to that of Fig. 2 and like elements are designated by like reference numerals. As in Fig. 9As shown, a second outer shell 25 is arranged on the outer shell 20 and is connected (e.g., glued) to the outer shell 20. The side of the second outer shell 25 facing away from the inner shell 21 forms the front side.

[0054] In the embodiment described here, the outer shell 20, which in the three-shell design can also be referred to as the channel shell 24, is thicker in the area of ​​the light-guiding channel 12 than in the remaining area. Of course, the channel shell 20 can also be designed with a constant thickness. Furthermore, the channel shell 20 extends over the entire first spectacle lens 3 and can thus also be referred to as a spacer shell 20, since it is always located between the inner shell 21 and the second outer shell 25, so that the second outer shell 25 is never in direct contact with the inner shell 21.

[0055] However, it is also possible for the channel shell 20 not to extend over the entire first spectacle lens 3. In particular, the channel shell 20 may extend only in the region of the light-guiding channel 12. In this case, in the other regions where the channel shell 20 is not present, there may be direct contact between the inner shell 21 and the second outer shell 25, as shown in Fig. 10 is shown schematically.

[0056] In Fig. 11a further embodiment is shown in which the light guide channel 12 in the first spectacle lens 3 is formed by a plane-parallel channel plate 26. The reflections for guiding the light rays 9 take place on the two side surfaces 27 and 28 of the channel plate 26. This can be achieved by a corresponding reflective layer on the side surfaces 27, 28. Furthermore, it is possible to arrange the channel plate 26 in the spectacle lens 3 such that there is a small air gap between the side surfaces 27 and 28 and the rest of the spectacle lens 3, so that light is guided by total internal reflection on the side surfaces 27 and 28. The spectacle lens 3 can be designed with a single shell or with at least two shells, as indicated by the dashed line 29.

[0057] 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 the virtual image is projected via both spectacle lenses 3, 4. The projected image can be projected in such a way that a three-dimensional image impression is created. However, this is not absolutely necessary.

[0058] The holding device 2 does not have to be designed as a glasses-like holding device 2. Any other type of holding device 2 is also possible, with which the display device 1 can be placed and worn on the head.

[0059] Since different visual impairments occur in practice, the curvature of the rear side 15 can, for example, be individually adjusted so that visual impairments in the range from -10 to +10 diopters can be corrected. Since the imaging optics 7 of the data channel must also be adjusted to the individual visual impairment, the curvature of the exit section 16 would also have to be adjusted for each visual impairment. This would require the design of an individual data channel (imaging optics 7) for each visual impairment. However, this would be very complex. The data channel can therefore advantageously be designed for a predetermined visual impairment range. For example, the diopter range from -10 diopters to +10 diopters can be divided into 5, 10 or 20 ranges, each of which would then cover a width of ± 2 diopters, ± 1 diopter or ± 0.5 diopter.This results in 5, 10, or 20 individually designed and pre-calculated data channels, for which all dimensions and curvatures are already specified. The curvature of the exit section 16 is also pre-defined. When designing the curvature of the inner side 15 in the remaining area, the curvature of the exit section 16 is then fixed and not changed. This allows for a simple, customized progressive lens 3 to be manufactured, which also provides excellent imaging properties for the displayed virtual image or for the data projection.

Claims

1. A spectacle lens for a display device (1) which can be placed on the head of a user and generates an image, wherein the spectacle lens (3) comprises a front side (19) and a rear side (15), an input section (11) and a deflection section (13) separated from the input section (11), an exit section (16) in the rear side (15), and a light guide channel (12) which guides light beams (9) from pixels of the generated image, which are input into the spectacle lens (3, 4) through the input section (11) of the spectacle lens (3, 4), in the spectacle lens (3, 4) as far as the deflection section (13), by which they are deflected in the direction of the exit section (16) and are then output from the spectacle lens (3, 4) through the exit section (16), wherein the light guide channel (12) within the spectacle lens (3, 4) comprises a reflective or partially reflective layer (22) at which at least one reflection takes place for guiding the light beams, wherein the spectacle lens (3, 4) is configured as a progressive power lens with a far-field region (F) and a near-field region (N), and the exit section (16), as seen in a plan view of the rear side (15) of the spectacle lens (3, 4), lies outside the far-field region (F) and outside the near-field region (N), characterized in that, wherein the curvature of the exit section (16) differs from the curvature of an intermediate region (24) of the rear side between the exit section (16) and the near-field region (N) in such a way that the ametropia correction when viewing the environment through the exit section (16) is inferior than when viewing the environment through the intermediate region (24).

2. The spectacle lens as claimed in claim 1, wherein the entire rear side (15) is configured as a continuous and differentiable surface.

3. The spectacle lens as claimed in one of the preceding claims, wherein the front side (19) is configured to be curved and the rear side (15) is configured to be curved.

4. The spectacle lens as claimed in one of the preceding claims, wherein the rear side (15) is configured as a freeform surface which carries out the ametropia correction.

5. The spectacle lens as claimed in one of the preceding claims, wherein the exit section (16) is configured to be spherically curved.

6. The spectacle lens as claimed in one of claims 1 to 4, wherein the exit section (16) is configured to be aspherically curved.

7. The spectacle lens as claimed in one of the preceding claims, wherein the front side is spherically curved.

8. The spectacle lens as claimed in one of the preceding claims, wherein the astigmatism in the exit section (16) is more than 1 diopter or more than 2 diopters.

9. The spectacle lens as claimed in one of the preceding claims, wherein the astigmatism in the near-field region (N) is not more than 1 diopter or not more than 0.5 diopters.

10. A display device having a holding device (2) which can be placed on the head of a user, an image generation module (5), which generates an image and which is fastened on the holding device (2), and imaging optics, which are fastened on the holding device (2) and which comprise a spectacle lens (3, 4) as claimed in one of the preceding claims and which image the generated image in the state of the holding device (2) placed on the head of the user, so that the user can perceive it as a virtual image.

11. A method for producing a spectacle lens as claimed in one of claims 1 to 9, wherein different ametropia ranges, which are respectively determined by a range of the aberrations to be corrected, are defined, for each ametropia range, a curvature profile of the exit section is calculated and this exit section is assigned to the ametropia range, the ametropia range in which the aberration value of the spectacle lens to be produced lies is determined, the curvature profile of the rear side of the spectacle lens to be produced is calculated therewith that the exit section assigned to the ametropia range determined is selected and its curvature profile is kept constant and not changed during the calculation of the curvature profile of the rear side, and the spectacle lens is produced on the basis of the calculated curvature profile of the rear side.