System for displaying a rear scene in a rearview mirror of a vehicle

Abstract

A system is provided for displaying a rear scene in a rearview mirror of a vehicle, the system comprising: a rearview mirror movably arranged within the vehicle and in a front region thereof, having a housing and a mirror, the rearview mirror being movable such that a driver can view a rear driving scene through the mirror; a display that can be arranged within the vehicle and in a region such that a rear wall thereof faces towards the driver and at least partially blocks the driver's view of the rear driving scene via the mirror; the system further comprising: a retroreflector arranged on the rear wall of the display; a projector arranged within the housing of the rearview mirror and fixedly mounted on the vehicle such that it can emit light through the mirror towards the retroreflector;wherein the mirror is designed in such a way in its optical properties that it at least partially transmits light emitted by the projector in the direction of the retroreflector and at least partially reflects light reflected by the retroreflector in the direction of the driver.

Description

[0001] The invention relates to a system for maintaining the functionality of the interior mirror despite the panoramic display.

[0002] Vehicles usually have a rear-view mirror (also known as an interior mirror) located in the front area, particularly the windshield, which allows the driver to look towards the rear of the vehicle and thus, among other things, view the traffic behind the vehicle (the rear driving scene) through the rear window. Vehicles are also known to have so-called panoramic displays. Such a panoramic display is located between the front area and the rear seats so that the passengers in the rear seats can view the display. A panoramic display is also usually designed so that when not in use it is arranged, for example, parallel to the roof lining and can be folded down or retracted when in use. In the latter state it is arranged in such a way that it blocks the driver's view to the rear via the rear-view mirror.

[0003] There are already ideas to compensate for the view of the interior mirror using rearview cameras and a display in the interior mirror. However, this approach has a significant disadvantage. In this case, the image from the display in the interior mirror would be very close to the eyes, in contrast to a conventional rearview mirror, where the driver looks at a distant driving scene. This short image distance requires the viewer to significantly refocus and change the convergence angle. This transition from long-distance to close-up vision takes time and is tiring, especially if the viewer frequently looks into the interior mirror.

[0004] There is also already the idea of ​​a double-sided display, in which another display is arranged on the back of the panoramic display and is visible on the interior mirror. In this case, an image captured, for example, by a camera located at the rear of the vehicle is shown on this display. Such a design is known, for example, from EP 2 627 538 B1 or US 2008 / 0 136 911 A1.

[0005] In addition, an entertainment system for the rear seats of a vehicle is known from US 2008 / 0 211 735 A1.

[0006] However, there is still room for improvement in providing the driver with the best possible view of the area behind the vehicle (the rear driving scene) via an interior mirror, despite the increased number of entertainment functions within the vehicle. Therefore, it is an object of this invention to provide a corresponding system. This object is achieved according to the invention by the features of the independent patent claims. Advantageous embodiments are the subject of the dependent claims.

[0007] A system is provided for displaying a rear scene in a rearview mirror of a vehicle, the system comprising: a rearview mirror movably arranged within the vehicle and in a front region thereof, having a housing and a mirror, the rearview mirror being movable such that a driver can view a rear driving scene through the mirror; a display that can be arranged within the vehicle and in a region such that a rear wall thereof faces towards the driver and at least partially blocks the driver's view of the rear driving scene via the mirror; the system further comprising: a retroreflector arranged on the rear wall of the display; a projector arranged within the housing of the rearview mirror and fixedly mounted on the vehicle such that it can emit light through the mirror towards the retroreflector;wherein the mirror is designed in such a way in its optical properties that it at least partially transmits light emitted by the projector in the direction of the retroreflector and at least partially reflects light reflected by the retroreflector in the direction of the driver.

[0008] Furthermore, it is intended that the mirror is designed as a partially transparent mirror.

[0009] Furthermore, it is intended that the mirror is designed as a semi-transparent mirror.

[0010] Furthermore, it is intended that the mirror is designed as a circular polarizer with a reflective polarizing filter.

[0011] Furthermore, it is provided that the mirror is designed as a foil stack consisting of a reflective linear polarizer arranged close to the projector and a quarter-wave retardation plate arranged far from the projector.

[0012] Furthermore, the projector is designed to emit linearly polarized light.

[0013] Furthermore, it is provided that the linear polarizer is designed to transmit s-polarized light and reflect p-polarized light or vice versa.

[0014] Furthermore, it is intended that the quarter-wave retardation plate is arranged at an orientation of 45 degrees to the linear polarizer so that it converts the light emitted by the projector into circularly polarized light.

[0015] Furthermore, it is provided that the system further comprises a diffuser which is arranged on the retroreflector and facing the mirror.

[0016] Furthermore, a vehicle is provided comprising the system.

[0017] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures of the drawing, which illustrate details of the invention, and from the claims. The individual features can be implemented individually or in combination in a variant of the invention.

[0018] Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawings. Fig. 1 shows a schematic representation of important components of the system according to an embodiment of the present invention. Fig. 2 shows an enlarged view of the rearview mirror with projector from Fig. 1. Fig. 3 schematically shows a beam path when using a partially transparent mirror of the rearview mirror according to an embodiment of the present invention. Fig. 4 schematically shows a beam path when using a mirror of the rearview mirror formed as a circular polarizer with a reflective polarizing filter according to an embodiment of the present invention.

[0019] In the following descriptions of the figures, the same elements or functions are provided with the same reference symbols.

[0020] The basic concept of the invention is that the rear scene normally visible to the driver through the rear view mirror arranged in the front area of ​​the vehicle is also visible to the driver in the rear view mirror when the view is obscured by a display arranged in an area behind the driver (e.g. in an area between the front seats and the rear seats and in the field of view of the mirror), such as a panoramic display. The term panoramic display is always used below, as this is the main application. Such a panoramic display can be a display with a housing (e.g. an LCD display) or without a housing (e.g. a screen). It can (due to its size) partially or completely block (or at least severely obstruct) the driver's view of a rear scene.The panoramic display can always obstruct the view when it is permanently installed or only when it is in the position of use, i.e. extended / folded down from the roof lining.

[0021] The problem is solved by the system described below, which is Fig. 1 is shown schematically. Fig. 2 shows an enlargement of the rearview mirror 11 with projector 2.

[0022] As is known, rearview mirrors 11 of a vehicle 1 have a housing 110 with which they are movably mounted (rotatable along two axes) in the interior of the vehicle 1. A mirror 111 is provided in an area facing the driver 3 or into the interior toward the rear of the vehicle 1, through which mirror, in particular, the driver 3 can view a rearward driving scene without having to turn around. The mirror 111 is adjusted—usually manually by the driver 3—so that it completely covers the so-called eyebox 30, i.e., the area in which the eye of the driver 3 can obtain the full viewing angle. Thus, the driver 3 can see the image reflected in the mirror 111 with both eyes.

[0023] According to the invention, a reflector, which is preferably formed as a retroreflector 121, is arranged on the side of the panoramic display 12 facing the driver 3, as shown in Fig. 1. A retroreflector 121 serves to reflect rays incident on it, e.g. light rays, regardless of the angle of incidence back into the same direction from which they struck it, i.e. back to the light source.

[0024] Furthermore, a projector 2 is provided behind the mirror 111 (and in the housing 110) of the rearview mirror 11, which emits images of a rearward driving scene (hereinafter also referred to simply as the image) through the mirror 111 toward the retroreflector 121. The light emitted by the projector 2 is advantageously linearly polarized light, but can also be unpolarized. The invention is described below with reference to a projector 2 that emits linearly polarized light.

[0025] Furthermore, the mirror 111 (or at least an exit window for the light emitted by the projector 2) of the rearview mirror 11 is formed in its optical properties such that light emerging from the projector 2 (and passing through the mirror 111) as well as light reflected by the retroreflector 121 to the mirror 111 is mirrored such that it is reflected in the direction of the observer (which is usually the driver 3).

[0026] According to the invention, the projector 2 is arranged in the housing 110 of the rearview mirror 11 and behind the mirror 111 (and thus not visible to the occupants of the vehicle 1). This projector is fixedly, i.e., immovably, connected to the vehicle 1, more precisely to the vehicle body 13, and is oriented such that it can project (moving) images toward the retroreflector 121 arranged on the rear of the panoramic display 12, i.e., project the desired image onto the retroreflector 121. The housing 110 of the rearview mirror 11, together with the mirror 111, is movably attached (rotatable about two axes) to the vehicle body 13, so that the mirror 111 can reflect the light rays reflected by the retroreflector 121, and thus the reflected image, toward the viewer (driver 3).

[0027] Furthermore, at least one recording device is provided at a rear (preferably outer) area of ​​the vehicle 1, e.g., a camera, which captures a rearward driving scene, normally directly captured via the rearview mirror 11, in real time and transmits it to the projector 2. Thus, a moving image is transmitted. The projector 2 serves to project the captured rearward driving scene through the mirror 111 onto the side of the panoramic display 12 facing the driver 3, i.e., onto the retroreflector 121 arranged there.

[0028] The retroreflector 121 can be a coating, a film, or a reflective (flat) component applied to the back of the panoramic display 12. This retroreflector 121 serves to reflect (moving) images of a rearward driving scene projected onto the retroreflector 121 by the projector 2 arranged in the rearview mirror 11 toward the rearview mirror 11 and by the mirror 111 of the rearview mirror 11 toward the driver 3, so that the driver can see the image emitted by the projector 2 in the mirror 111 of the rearview mirror 11.

[0029] Since the projector 2 is arranged behind the mirror 111 and the projection must pass through the mirror 111 before reaching the retroreflector 121, the mirror 111 must have suitable optical properties so that the image can also be seen by the viewer (driver 3) in the mirror 111. For this purpose, the mirror 111, or at least an exit window thereof, is formed either as a partially transparent mirror 111.0 or as a circular polarizer with a reflective polarizing filter.

[0030] In Fig. Figure 3 shows a design in which the mirror 111 is shown as a partially transparent mirror 111.0, here as a semi-transparent mirror 111.0, which transmits 50% of the light and reflects 50%. The design as a semi-transparent mirror 111.0 is a preferred design when using a partially transparent mirror 111.0, as this allows the highest efficiency for the projector light to be achieved. This is a highly simplified representation, as it shows the intensity of the projector light in the beam path without considering Fresnel or scattering losses.

[0031] The reflection levels of the mirror 111 are not limited and can be selected by the person skilled in the art depending on the desired brightness of the image on the mirror 111 of the rearview mirror 11.

[0032] The following describes the course of the light rays emitted by the projector 2 with reference to Fig. 3, in which the design of the mirror 111 is shown as a partially transparent mirror 111.0 with a reflection factor of 50% (i.e., as a semi-transparent mirror 111). In the illustrated design, the projector 2 emits linearly polarized light with 100% intensity in the direction of the retroreflector 121 provided on the panoramic display 12. After the light passes through the exit window (the mirror 111 or a predetermined portion thereof), the intensity of the light is reduced to 50% due to the partial transparency of the mirror 111. The retroreflector 121 of the panoramic display 12, in turn, reflects the light rays incident on it back towards the mirror 111 (more precisely, back to the exit window) without loss. After reflection at the partially transparent mirror 111.0, in turn, light is reflected towards the viewer with 50% intensity, so that in this example a total of 25% of the intensity of the light rays emitted by projector 2 reaches the viewer (driver 3).

[0033] In case the mirror 111 is formed as a circular polarizer with a reflective polarizing filter, as in Fig. As shown in Figure 4, the mirror 111 (the exit window) comprises or is formed from a foil stack consisting of a reflective linear polarizer 111.1 (reflective polarizing filter) positioned near the projector and a quarter-wavelength (λ / 4) retardation plate 111.2 positioned far from the projector. This arrangement has an efficiency of 100% (great simplification) when neglecting Fresnel, scatter, and other losses. Furthermore, this variant is the most energy-efficient implementation.

[0034] The following describes the course of the light rays emitted by the projector 2 with reference to Fig.4 and the design of the mirror 111 as a circular polarizer with a reflective polarizing filter. In the illustrated design, the projector 2 emits linearly polarized light (s- or p-polarized) with an intensity of 100% toward the retroreflector 121 provided on the panoramic display 12. This light strikes the reflective linear polarizer 111.1 and is ideally transmitted at 100%. For this purpose, the polarizing filter of the linear polarizer 111.1 is aligned such that it transmits the light emitted by the projector and reflects other, linearly polarized light (e.g., it transmits s-polarized light if emitted by the projector 2 and reflects p-polarized light). The light then passes through the quarter-wave retardation plate 111.2 (also called a lambda / 4 retarder), which is oriented (preferably at 45° to the polarizer) so that the linearly polarized light is rotated into circularly polarized light. The intensity is unaffected.

[0035] The retroreflector 121 of the panoramic display 12 reflects the light incident there and now circularly polarized without loss and without a change in polarization (the retroreflector 121 is designed as a circularly polarization-maintaining retroreflector 121).

[0036] The circularly polarized light now passes through the quarter-wave retardation plate 111.2 for the second time and is transformed into linearly polarized light (in the above example, p-polarized light). The linearly polarized light then hits the reflective polarizing filter (also called a polarization filter) of the linear polarizer 111.1 and is reflected back toward the viewer without loss. It then passes through the quarter-wave retardation plate 111.2 again without loss and is once again converted into circularly polarized light. The viewer (driver 3) receives 100% of the emitted intensity.

[0037] The advantage of this design is that because the light is circularly polarized, it can also be seen with polarized sunglasses.

[0038] If the projector emits unpolarized light, it is linearly polarized after passing through the polarizing filter (linear polarizer 111.1). The remaining beam path is the same.

[0039] In all cases, the light is reflected towards the viewer (driver 3) by the corresponding orientation of the mirror 111 after being reflected by the retroreflector 121 of the panoramic display 12.

[0040] If the retroreflector 121 reflects the light to the mirror 111 without any significant scattering, only a very small area of ​​the eyebox 30 is illuminated. In the worst case, this can result in only one eye of the viewer (driver 3) being able to see the projector image in the mirror 111. In order to illuminate a sufficiently large area of ​​the eyebox 30, a diffuser 121.1 can be applied to the retroreflector 121 of the panoramic display 12 (i.e., facing the mirror 111). This diffuser can exhibit varying degrees of scattering in the horizontal and vertical directions, e.g., 3° ​​horizontal, 1° vertical, or 5° horizontal, 2° vertical, etc. A diffuser 121.1 can be provided as a coating, a film, or a separate component on the retroreflector 121.

[0041] The proposed system significantly improves the problem of strong refocusing, which occurs in systems that display a camera image directly in the rearview mirror 11.

[0042] Furthermore, a very compact and efficient setup is provided, since the use of the retroreflector 121 reflects the light from projector 2 very precisely back to the projector 2 and thus to the mirror 111. This means that hardly any light is lost in angles that do not reach the eye of the driver 3. This not only creates a very energy-efficient system, it is also barely visible from the outside.

[0043] The system is preferably installed in vehicles with a panoramic display, as this blocks the driver's view to the rear. List of reference symbols 1 vehicle 11 Rearview mirror 110 housings 111 Mirror / Exit window 111.0 partially transparent mirror 111.1 reflective linear polarizer 111.2 Quarter-wave delay plate 12 panoramic display 121 Retroreflector 121.1 Diffuser 13 Vehicle body 2 projectors 3 drivers / viewers 30 Eyebox

Claims

[1] System for displaying a rear scene in a rearview mirror (11) of a vehicle (1), the system comprising: - a rearview mirror (11) movably arranged within the vehicle (1) and in a front region thereof, comprising a housing (110) and a mirror (111), wherein the rearview mirror (11) can be moved such that a driver (3) can view a rear driving scene through the mirror (111), - a display (12) which can be arranged within the vehicle (1) and in an area such that a rear wall thereof faces towards the driver (3) and at least partially blocks the driver's (3) view of the rear driving scene via the mirror (111), the system further comprising: - a retroreflector (121) arranged on the rear wall of the display (12), - a projector (2) arranged within the housing (110) of the rearview mirror (11) and fixedly mounted on the vehicle (1) in such a way that it can emit light through the mirror (111) in the direction of the retroreflector (121), wherein - the mirror (111) is designed in such a way in its optical properties that it at least partially transmits light emitted by the projector (2) in the direction of the retroreflector (121) and at least partially reflects light reflected by the retroreflector (121) in the direction of the driver (3). [2] System according to claim 1, wherein the mirror (111) is designed as a partially transparent mirror (111.0). [3] System according to claim 2, wherein the mirror (111) is designed as a semi-transparent mirror (111.0). [4] System according to claim 1, wherein the mirror (111) is designed as a circular polarizer with a reflective polarizing filter. [5] System according to claim 4, wherein the mirror (111) is designed as a foil stack comprising a reflective linear polarizer (111.1) arranged close to the projector and a quarter-wave retardation plate (111.2) arranged remote from the projector. [6] System according to one of the preceding claims, wherein the projector (2) emits linearly polarized light. [7] System according to claim 6 with reference back to claim 5, wherein the linear polarizer (111.1) is arranged to transmit s-polarized light and reflect p-polarized light or vice versa. [8] System according to claim 5, wherein the quarter wave plate (111.2) is arranged in an orientation of 45 degrees to the linear polarizer (111.1) so that it converts the light emitted by the projector (2) into circularly polarized light. [9] System according to one of the preceding claims, further comprising a diffuser (121.1) arranged on the retroreflector (121) and facing the mirror (111). [10] Vehicle (1) comprising the system according to one of the preceding claims.

Images