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

Abstract

The invention relates to a system for displaying a rear scene in a rearview mirror of a vehicle, the system having a rearview mirror which is movably arranged in the interior of the vehicle and in a front region of the vehicle, the rearview mirror having a housing and a mirror, the rearview mirror being movable such that a driver can view a rearward driving scene through the mirror, a display screen which is arrangeable in the interior of the vehicle and in a region such that a rear wall of the display screen faces the driver and at least partially blocks the driver's line of sight for viewing the rearward driving scene through the mirror, the system further comprising a retroreflector which is arranged on the rear wall of the display screen, a projector which is arranged in the interior of the housing of the rearview mirror and is fixed immovably to the vehicle such that the projector can emit light rays through the mirror toward the retroreflector, wherein the optical properties of the mirror are designed such that the mirror allows at least partial transmission of the light rays emitted by the projector toward the retroreflector and at least partial reflection of the light rays reflected by the retroreflector in the direction of the driver.

Description

Technical Field

[0001] This invention relates to a system that maintains the function of the interior rearview mirror even in the presence of a panoramic display screen. Background Technology

[0002] Vehicles are typically equipped with rearview mirrors, which are mirrors located in the front area (especially the windshield) (also known as interior rearview mirrors). Drivers can use these mirrors to look behind the vehicle, and especially through the rear windshield, observe traffic conditions (driving scenes behind the vehicle). Additionally, vehicles are known to be equipped with so-called panoramic displays. These displays are positioned between the front area of ​​the vehicle and the rear seats, allowing rear passengers to view the screen. Panoramic displays are often designed to be parallel to the headliner when not in use, and can be folded or moved to a usable position when in use. In the latter state, their arrangement obstructs the driver's view of the rear through the rearview mirrors.

[0003] Concepts already exist that use a reversing camera and a display screen in the rearview mirror to compensate for the rearview mirror's field of vision. However, this solution has a significant drawback. In this case, the image on the rearview mirror's display screen is very close to the eye, which is quite different from a traditional rearview mirror where the driver sees distant driving scenes. This shorter image distance requires the observer to make strong refocusing movements and change the convergence angle. This switching from far-sighted to near-sighted vision is both time-consuming and easily causes fatigue, especially when frequently looking at the rearview mirror.

[0004] Furthermore, the concept of a dual-display system exists, which involves placing another display screen behind the panoramic display screen, visible in the rearview mirror. In this case, an image captured, for example, by a camera positioned in the rear area of ​​the vehicle would be displayed on this screen. Such designs have been disclosed, for example, in EP 2 627 538 B1 or US 2008 0 136 911 A1.

[0005] However, in order to provide the driver with the best possible view of the area behind the vehicle (rear driving scene) via the rearview mirror while incorporating increasingly sophisticated in-vehicle entertainment features, there is still room for improvement. Therefore, the object of this invention is to provide a corresponding system. According to the invention, this object is achieved through the features of the independent claim. Advantageous designs are the subject of the dependent claims. Summary of the Invention

[0006] The present invention provides a system for displaying a rear view scene in a vehicle's rearview mirror, the system comprising: a rearview mirror movably arranged inside the vehicle and in the front region of the vehicle, the rearview mirror having a housing and a mirror, the rearview mirror being movable to allow a driver to observe a driving scene behind the vehicle through the mirror; a display screen arranged inside the vehicle and in a region such that the rear wall of the display screen faces the driver and at least partially obstructs the driver's view of the driving scene behind the vehicle through the mirror; the system further comprising: a retroreflector arranged on the rear wall of the display screen; and a projector arranged inside the housing of the rearview mirror and immovably fixed to the vehicle, such that the projector can emit light through the mirror toward the retroreflector, wherein the optical characteristics of the mirror are designed such that the mirror allows at least partial transmission of light emitted by the projector toward the retroreflector and at least partial reflection of light reflected by the retroreflector toward the driver.

[0007] Furthermore, the mirror structure is specified as a partially transparent mirror.

[0008] Furthermore, the mirror is specified as a semi-transparent mirror.

[0009] Furthermore, the mirror is configured as a circular polarizer with a reflective polarizing filter.

[0010] Further specified, the mirror structure is a thin film stack, which includes a reflective linear polarizer arranged close to the projector and a quarter-wavelength delay plate arranged away from the projector.

[0011] Furthermore, it is specified that the projector emits linearly polarized light.

[0012] Furthermore, the linear polarizer is configured to transmit s-polarized light and reflect p-polarized light, or vice versa.

[0013] Furthermore, the quarter-wavelength delay plate is oriented at a 45-degree angle relative to the linear polarizer, such that it converts the light emitted by the projector into circularly polarized light.

[0014] Furthermore, the system also includes a diffuser arranged on the retroreflector and facing the mirror.

[0015] Furthermore, the present invention also provides a vehicle having the aforementioned system.

[0016] Other features and advantages of the invention will become apparent from the following description of embodiments of the invention with the aid of the accompanying drawings, which illustrate details of the invention, and from the claims. Various features may be implemented individually or in any combination in variations of the invention. Attached Figure Description

[0017] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0018] Figure 1 A schematic diagram of key components of a system according to an embodiment of the present invention is shown.

[0019] Figure 2 A projector is shown. Figure 1 A magnified view of the rearview mirror in the image.

[0020] Figure 3 The optical path is schematically shown when using a partial transparent mirror of a rearview mirror according to an embodiment of the present invention.

[0021] Figure 4 The optical path is schematically illustrated when using a rearview mirror constructed as a circular polarizer with a reflective polarizing filter according to an embodiment of the present invention. Detailed Implementation

[0022] In the following description of the figures, the same elements or functions are referred to by the same reference numerals.

[0023] The basic concept of this invention is that even if the driver's line of sight is obstructed by a display screen, such as a panoramic display screen, located in the area behind the driver (e.g., in the area between the front and rear seats and within the field of view of the rearview mirror), the rear view that the rearview mirror, located in the area at the front of the vehicle, would normally provide to the driver can still be seen in the rearview mirror. The term "panoramic display screen" will be used throughout this invention because it is the primary application scenario. Such a panoramic display screen can be a housing-mounted display device (e.g., an LCD screen) or a housing-less display device (e.g., a screen). Due to its size, it may partially or completely obstruct (or at least severely impede) the driver's observation of the rear view. Here, if the panoramic display screen is fixedly mounted, it may always obstruct the view; or only when it is in its usable position (i.e., unfolded / folded down from the headliner).

[0024] The above problem is solved by the system described below, which... Figure 1 It is shown schematically in the diagram. Figure 2 An enlarged view of the rearview mirror 11 and the projector 2 is shown.

[0025] It is known that the rearview mirror 11 of vehicle 1 has a housing 110 through which the rearview mirror can be movably (rotatable about two axes) mounted in the interior area of ​​vehicle 1. The mirror 111 is positioned in an area facing the driver 3 or towards the rear of vehicle 1 and pointing towards the interior space, through which the driver 3 can observe the driving scene behind without turning around. Here, the mirror 111 is typically manually adjusted by the driver 3 so that it completely covers the so-called eyebox 30, even the area where the driver 3's eyes can obtain a full viewing angle. Therefore, the driver 3 can see the image reflected in the mirror 111 with both eyes.

[0026] According to the present invention, a reflector is arranged on the side of the panoramic display screen 12 facing the driver 3, which is preferably configured as a retroreflector 121, such as... Figure 1 As shown. Retroreflector 121 is used to reflect incident beams (e.g., light beams) back to their incident direction, i.e., back to the light source, regardless of the incident angle.

[0027] Furthermore, a projector 2 is disposed behind the mirror 111 of the rearview mirror 11 (and within the housing 110), which projects an image of the driving scene behind (hereinafter also simply referred to as the image) through the mirror 111 toward the retroreflector 121. Advantageously, the light emitted by the projector 2 is linearly polarized light, but it can also be unpolarized light. The invention will now be described based on the projector 2 emitting linearly polarized light.

[0028] Furthermore, the optical characteristics of the mirror 111 (or at least the light exit window emitted by the projector 2) of the rearview mirror 11 are designed such that light emitted from the projector 2 (and passing through the mirror 111) and light reflected from the retroreflector 121 to the mirror 111 are reflected so that they are emitted toward the observer (usually the driver 3).

[0029] According to the invention, the projector 2 is arranged within the housing 110 of the rearview mirror 11 and located behind the mirror 111 (therefore, it is not visible to the passengers of vehicle 1). The projector is fixedly (i.e., immovably) connected to vehicle 1 (more specifically, vehicle body 13) and is oriented such that it can emit (dynamic) images toward a retroreflector 121 arranged on the back of the panoramic display screen 12, i.e., project the desired image onto the retroreflector 121. The housing 110 of the rearview mirror 11 is movably (rotatable about two axes) fixed to the vehicle body 13 together with the mirror 111, so that the mirror 111 can reflect the light beam reflected by the retroreflector 121 and thus the reflected image toward the observer (driver 3).

[0030] Furthermore, at least one imaging device (e.g., a camera) is provided in the rear (preferably external) area of ​​vehicle 1. This imaging device captures in real time the driving scene behind the vehicle, which can usually be directly observed through the rearview mirror 11, and transmits it to the projector 2. Therefore, what is transmitted is a dynamic image. The projector 2 is used to project the captured driving scene behind the vehicle through the mirror 111 onto the driver-facing side of the panoramic display screen 12 (i.e., onto the retroreflector 121 arranged there).

[0031] The retroreflector 121 may be a coating, a thin film, or a reflective (planar) component applied to the back of the panoramic display screen 12. The retroreflector 121 is used to reflect a (dynamic) rear driving scene image projected onto the retroreflector 121 by the projector 2 arranged in the rearview mirror 11 back to the direction of the rearview mirror 111, and reflected to the direction of the driver 3 through the mirror 111 of the rearview mirror 11, so that the driver can see the image emitted by the projector 2 in the mirror 111 of the rearview mirror 11.

[0032] Since the projector 2 is positioned behind the mirror 111 and the projection must pass through the mirror 111 to reach the retroreflector 121, the mirror 111 must have appropriate optical properties so that the observer (driver 3) can see the image in the mirror 111. For this purpose, the mirror 111 (or at least its exit window) is either constructed as a partially transparent mirror 111.0 or as a circular polarizer with a reflective polarizing filter.

[0033] Figure 3 One embodiment is shown where mirror 111 is configured as a partially transparent mirror 111.0 (here, a semi-transparent mirror 111.0), allowing 50% of the light to pass through and reflecting 50% of the light. The semi-transparent mirror 111.0 design is preferred when using a partially transparent mirror 111.0 because it achieves the highest efficiency of the projector light in this case. This illustration is a highly simplified diagram because the intensity of the projector light in the optical path does not account for Fresnel losses or scattering losses.

[0034] The reflectivity of mirror 111 is not limited, and those skilled in the art can select it based on the desired brightness of the image on mirror 111 of the rearview mirror 11.

[0035] The following will be referenced Figure 3 Describe the propagation path of the light emitted by projector 2. Figure 3The mirror 111 shown is constructed as a partially transparent mirror 111.0 with a reflectivity of 50% (i.e., a semi-transparent mirror 111). In the illustrated embodiment, the projector 2 emits linearly polarized light with an intensity of 100% towards the retroreflector 121 disposed on the panoramic display screen 12. After the light passes through the exit window (mirror 111 or a predetermined portion thereof), the light intensity is reduced to 50% due to the partial transparency of mirror 111. The retroreflector 121 of the panoramic display screen 12 then reflects the incident light beam back to the direction of mirror 111 without loss (more specifically, back to the exit window). After being reflected by the partially transparent mirror 111.0, 50% intensity of the light is reflected back to the observer's direction; therefore, in this example, a total of 25% of the intensity of the light beam emitted by the projector 2 reaches the observer (driver 3).

[0036] If mirror 111 is constructed as a circular polarizer with a reflective polarizing filter (such as...) Figure 4 As shown), mirror 111 (emission window) has or is composed of a thin-film stack, which includes a reflective linear polarizer 111.1 (reflective polarizing filter) arranged close to the projector and a quarter-wavelength (λ / 4) delay plate 111.2 arranged away from the projector. Ignoring Fresnel loss, scattering loss, and other losses, the efficiency of this arrangement is 100% (highly simplified). Furthermore, this variant is the most energy-efficient implementation.

[0037] The following will be referenced Figure 4 The image describes the path of the light beam emitted by the projector 2, along with a mirror 111 constructed as a circular polarizer with a reflective polarizing filter. In the illustrated embodiment, the projector 2 emits linearly polarized light (s-polarized or p-polarized light) with 100% intensity toward a retroreflector 121 disposed on the panoramic display screen 12. This light is incident on a reflective linear polarizer 111.1 and ideally transmits 100%. For this purpose, the polarizing filter of the linear polarizer 111.1 is oriented such that it transmits the light emitted by the projector and reflects other linearly polarized light (e.g., if the projector 2 emits s-polarized light, the polarizing filter transmits s-polarized light and reflects p-polarized light). The light then passes through a quarter-wavelength delay plate 111.2 (also called a λ / 4 delayer), which is oriented (advantageously at 45° relative to the polarizer) such that the linearly polarized light is converted into circularly polarized light. The intensity remains unaffected.

[0038] The retroreflector 121 of the panoramic display 12 reflects the light rays that are incident on it there and are now circularly polarized without loss and without changing the polarization state (the retroreflector 121 is constructed to maintain circular polarization).

[0039] The circularly polarized light now passes through the quarter-wave delay plate 111.2 for the second time and changes to linearly polarized light (p-polarized light in the example above). This linearly polarized light is now incident on the reflective polarizing filter (also called the polarizing filter) of the linear polarizer 111.1 and is reflected without loss to the observer's direction, while again passing without loss through the quarter-wave delay plate 111.2 and changing back to circularly polarized light. The observer (driver 3) finally receives 100% emission intensity.

[0040] The advantage of this embodiment is that, since the light is circularly polarized, it can be seen even when wearing polarized sunglasses.

[0041] If the projector emits unpolarized light, the light becomes linearly polarized after passing through a polarizing filter (linear polarizer 111.1). The rest of the optical path is the same.

[0042] In all cases, after the light is reflected by the retroreflector 121 of the panoramic display 12, the light is reflected in a corresponding direction by the mirror 111 toward the observer (driver 3).

[0043] If there is no significant scattering when the light reflected from the retroreflector 121 reaches the mirror 111, only a very small area of ​​the viewing window 30 will be illuminated. In the worst case, this could result in the observer (driver 3) only being able to see the projector image in the mirror 111 with one eye. To illuminate a reasonably large area of ​​the viewing window 30, a diffuser 121.1 can be provided on the retroreflector 121 of the panoramic display screen 12 (i.e., facing the mirror 111). This diffuser can have different scattering characteristics in the horizontal and vertical directions, such as 3° horizontally and 1° vertically, or 5° horizontally and 2° vertically, etc. The diffuser 121.1 can be provided on the retroreflector 121 in the form of a coating, a thin film, or a separate component.

[0044] The proposed system significantly improves upon the severe refocusing problem present in systems that display camera images directly in the interior rearview mirror 11.

[0045] Furthermore, a very compact and efficient setup is provided: by using the retroreflector 121, the light from the projector 2 is reflected back to the projector 2 in a very targeted manner, and then reflected back to the mirror 111. That is to say, there is almost no light loss within the angular range that cannot reach the driver 3's eyes. Therefore, not only is a very energy-efficient system achieved, but the system is also virtually invisible from the outside.

[0046] The system is preferably installed in vehicles with panoramic displays, because the driver's rear view is obstructed in such vehicles.

[0047] List of reference numerals in the attached diagram:

[0048] 1 vehicle

[0049] 11 Rearview Mirrors

[0050] 110 housing

[0051] 111 Mirrors / Exit Window

[0052] 111.0 Partial Transmission Lens

[0053] 111.1 Reflective Linear Polarizer

[0054] 111.2 Quarter Wavelength Delay Plate

[0055] 12 panoramic displays

[0056] 121 retroreflector

[0057] 121.1 Diffuser

[0058] 13 vehicle bodies

[0059] 2 projectors

[0060] 3 Drivers / Observers

[0061] 30 windows.

Claims

1. A system for displaying a rear view scene in a rearview mirror (11) of a vehicle (1), the system having: - A rearview mirror (11) movably arranged inside the vehicle (1) and in the front area of ​​the vehicle, the rearview mirror having a housing (110) and a mirror (111), the rearview mirror (11) being movable to allow the driver (3) to observe the driving scene behind through the mirror (111); - A display screen (12) that can be arranged inside the vehicle (1) and in one area such that the rear wall of the display screen faces the driver (3) and at least partially obstructs the driver's (3's) view of the driving scene behind through the mirror (111). The system also includes: - A retroreflector (121) is arranged on the rear wall of the display screen (12). - A projector (2) is arranged inside the housing (110) of the rearview mirror (11) and fixed immovably to the vehicle (1), such that the projector can emit light through the mirror (111) toward the retroreflector (121). The optical characteristics of the mirror (111) are designed such that light emitted by the projector (2) toward the retroreflector (121) is at least partially transmitted through the mirror, and light reflected by the retroreflector (121) is at least partially reflected toward the driver (3).

2. The system according to claim 1, wherein, The mirror (111) is constructed as a partially transparent mirror (111.0).

3. The system according to claim 2, wherein, The mirror (111) is constructed as a semi-transparent mirror (111.0).

4. The system according to claim 1, wherein, The mirror (111) is constructed as a circular polarizer with a reflective polarizing filter.

5. The system according to claim 4, wherein, The mirror (111) is constructed as a thin film stack, which includes a reflective linear polarizer (111.1) arranged close to the projector and a quarter-wavelength delay plate (111.2) arranged away from the projector.

6. The system according to any one of the preceding claims, wherein, The projector (2) emits linearly polarized light.

7. The system according to claim 6, wherein, The linear polarizer (111.1) is configured to transmit s-polarized light and reflect p-polarized light, or to transmit p-polarized light and reflect s-polarized light.

8. The system according to claim 4 or 5, wherein, The quarter-wave delay plate (111.2) is oriented at 45 degrees relative to the linear polarizer (111.1) so that the quarter-wave delay plate converts the light emitted by the projector (2) into circularly polarized light.

9. The system according to any one of the preceding claims, the system further comprising a diffuser (121.1) arranged on the retroreflector (121) and facing the mirror (111).

10. A vehicle (1) having a system according to any one of the preceding claims.

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