Display device

Abstract

The vehicle display device (10) with an infrared camera includes a display (18) and a backlight unit (26), the display (18) having a front surface with a display surface (24) and a rear surface, the backlight unit (26) having a backlight light source (38) and a light guide (28), the light guide (28) having a light exit surface (30), an opposite rear surface (32), and a peripheral edge surface (34) connecting the front surface to the rear surface (32), the backlight light source (38) irradiating visible light onto at least a partial region of the edge surface (34). There is no optical light diffusion element in the space between the rear surface of the display (18) and the light exit surface (30) of the light guide (28). The display device 10 further includes a reflective film, an infrared light source 46, and an infrared photodiode array 48. The reflective film is disposed on or opposite the rear surface of the light guide 28 and is configured to reflect backlight 36 and transmit infrared light. The reflective film has a rear surface opposite the light guide 28, and the infrared light source 46 and the infrared photodiode array 48 are all disposed opposite the rear surface of the reflective film. Infrared light from the infrared light source 46 passes through the reflective film, the light guide 28, and the display 18 to reach an area in front of the display surface 24. The infrared light from the infrared light source 46 reflected by objects that may be present in this area passes through the display 18, the light guide 28, and the reflective film to reach the infrared photodiode array 48.

Description

[Technical Field]

[0001] The present invention relates to a vehicle display device with an infrared camera, and more particularly to a display device in which the infrared camera is positioned behind the display surface of the display, i.e., behind the surface of the display device that is usually surrounded by a frame around the display. [Background technology]

[0002] To increase vehicle safety, it has long been known to monitor the interior of a vehicle for possible safety risks, in particular to detect the driver's face, for example by using eyelid movements to enable early detection of driver fatigue and to output a corresponding warning signal.

[0003] For various reasons, it is desirable for the camera used for this purpose to be a component of the display device used in the instrument panel. To accommodate the camera in such a display device, the frame that usually surrounds the display device is generally suitable. However, for optical reasons, there is an increasing trend to make this frame as narrow as possible, so that in this area there is no space left to accommodate the camera. The same can be said for the edge area of ​​the display itself, which is usually colored black on the display surface.

[0004] For example, it is known to place an infrared camera behind the display and its backlight unit. An example of such a concept is described in EP 3608147. However, this known system results in the use of two different stacks of "optical films," one for the infrared camera and one for the actual display surface, which may not be desirable.

[0005] From US 2010 / 0073584 A1, a vehicle display device with an infrared camera is known, in which no reflective polarizing filter is arranged behind the display for the backlight light that backlights the display.

[0006] From DE 10 2009 002 184 A1 a head-up display is known which is provided with a projection unit, the projection light of which passes through a reflective polarizing film before reaching the windscreen.

[0007] Further display devices are described in DE 102019001333 A1 and DE 102016224246 A1. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] European Patent Application Publication No. 3608147 [Patent Document 2] US Patent Application Publication No. 2010 / 0073584 [Patent Document 3] German Patent Application Publication No. 102009002184 [Patent Document 4] German Patent Application Publication No. 102019001333 [Patent Document 5] German Patent Application Publication No. 102016224246 Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a vehicle display device with an infrared camera in which the configuration and arrangement of the individual optical layers, photoelectric layers and lighting layers are the same for the display surface area and for the infrared camera. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention proposes Especially the LCD display, A backlight unit; A reflective film; Infrared light source and an infrared photodiode array; a first specularly reflective polarizing film; An infrared camera-equipped vehicle display device comprising: the display has a front surface having a display surface and a rear surface; the backlight unit has a backlight light source and a light guide, the light guide has a light exit surface, an opposite rear surface, and a peripheral edge surface connecting the front surface to the rear surface; the backlight source irradiates visible light onto at least a partial region of the edge surface; a space between the rear surface of the display and the light exit surface of the light guide is free of optical light diffusing elements; the reflective film is disposed on or opposite the rear surface of the light guide and is configured to reflect backlight and transmit infrared light; the reflective film has a rear surface opposite the light guide; the infrared light source and the infrared photodiode array are all disposed opposite the rear surface of the reflective film; the first specularly reflective polarizing film is disposed on or opposite the rear surface of the display and is configured to reflect visible backlight light, the polarization of which is offset from the polarization direction of a polarizing filter on the rear side of the display; the backlight reflected by the specular reflective polarizing film can be reflected back by the reflective film after changing the polarization direction of the backlight to the direction of the specular reflective polarizing film; The display device is one in which infrared light from the infrared light source passes through the reflective film, the light guide, the first specular reflective polarizing film, and the display to reach an area in front of the display surface, and the infrared light from the infrared light source reflected by an object that may be present in this area passes through the display, the first specular reflective polarizing film, the light guide, and the reflective film to reach the infrared photodiode array.

[0011] The display device according to the present invention, which may also have operating functions if necessary, comprises a display, typically implemented in LCD technology, having a front surface with a viewing surface and a rear surface. Behind the display, a backlight unit is provided, which has a light guide, which has a light exit surface, an opposite rear surface, and a peripheral edge surface connecting the front surface to the rear surface. A backlight source in the backlight unit supplies its visible backlight light to the light guide from the edge side (edge ​​type). The light guide itself is typically configured as a plate or thin film. The space between the rear surface of the display and the light exit surface of the light guide is free of any optical light diffusion elements.

[0012] A reflective film for reflecting backlight and transmitting infrared light (hereinafter also referred to as infrared light) is provided facing the rear surface of the light guide, and this infrared-transmitting reflective film may be a component of the rear surface of the light guide. The reflective film has a rear surface opposite the light guide. An example of a material that transmits infrared light and reflects (visible) light is described in, for example, U.S. Patent No. 5,233,465.

[0013] An infrared source (hereinafter also referred to as an infrared light source) and an infrared photodiode array (as an infrared camera) are provided facing the rear surface of the infrared transmitting and reflecting film. Infrared light from the infrared light source passes through the reflecting film, the light guide, and the display to reach an area in front of the display surface. There, it is reflected by an object such as a hand or a person (driver monitoring), and reaches the infrared photodiode array via the display, the light guide, and the infrared transmitting and reflecting film.

[0014] According to another aspect of the present invention, a display device includes a first specular-reflective polarizing film disposed on or facing the rear of the display, the first specular-reflective polarizing film configured to reflect visible backlight light, the polarization of which is offset from the polarization direction of the polarizing filter on the rear side of the display, such that the backlight reflected by the specular-reflective polarizing film can be re-polarized back into the direction of the specular-reflective polarizing film and reflected back. The (first) specular-reflective polarizing film reflects backlight light, the polarization of which does not match the direction of the polarizing filter on the rear side of the display. Such backlight light is then reflected back to the infrared-transmitting reflective film, where it is re-polarized and reflected back. This allows light that would otherwise be absorbed by the polarizing filter on the rear side of the display to be used for backlighting the display. A specularly reflective polarizer that can be used in the framework of this embodiment and in the developments of the invention described below is offered by the American company 3M under the name 3M APF (3m-automotive-reflective-polarizer-3m-arp-320-tech-data-sheet.pdf).

[0015] The display device concept of the present invention has the advantage that no space is required in the frame or edge area of ​​the display device to accommodate an infrared camera, maximizing the size of the display surface, although this reduces the luminous intensity of the display backlight, since the entire display device, i.e., the display and backlight unit, must be transparent to infrared light.

[0016] Light guide films with minimal prism structures are particularly suitable as light guides for backlight units. Such light guide films are sold, for example, by the Finnish company Nanocomp Oy (https: / / www.nanocomp.fi / wp-content / uploads / 2022 / 04 / nanocomp_directional_light_guide_film_lowres_4-2022.pdf).

[0017] Such a light guide film can also be disposed by optical bonding on a conventional light guide that does not have a structure on the light exit surface.

[0018] This light-guiding film provides optimal homogenization of the backlight light without the need for additional light-diffusing elements that are typically placed between the backlight unit and the display.

[0019] In another useful embodiment of the present invention, the first specularly reflective polarizing film also reflects infrared light, the polarization of which is shifted from the polarization direction of the polarizing filter on the rear side of the display, and an infrared-reflecting film is disposed below the infrared light source to reflect the infrared light reflected by the first specularly reflective polarizing film with a different polarization direction. In this way, the specularly reflective polarizing film can also be used to enhance the utilization of infrared light.

[0020] Preferably, a second specular-reflective polarizing film for reflecting infrared light is disposed on or facing the rear surface of the infrared-transmitting-reflective film, and its polarization is shifted from the polarization direction of the polarizing filter on the rear surface side of the display, and an infrared-reflective film for changing the polarization direction of the infrared light reflected by the second specular-reflective polarizing film and reflecting it is disposed below the infrared light source. Thus, in this embodiment, the second specular-reflective polarizing film contributes to improving the infrared light yield.

[0021] Typically, the infrared light source emits near-infrared light, and therefore the infrared photodiode array is a near-infrared photodiode array. The photodiode array can basically be configured one-dimensionally or two-dimensionally.

[0022] As described above, by incorporating a touch sensor system that can be realized by a touch panel, for example, the display surface of the display can also be used to input commands by touching the display surface.

[0023] Furthermore, an infrared optical lens may be disposed between the infrared transmitting and reflecting film and the infrared photodiode array.

[0024] According to a useful aspect of the present invention, a diffusion layer for scattering backlight may be provided in the space between the light exit surface of the light guide and the rear surface of the display, and the diffusion layer may transmit infrared light from the infrared light source without scattering it. According to another useful aspect of the present invention, the diffusion layer that is neutral to infrared light may be disposed between the light guide and the specular reflective polarizing film, or between the specular reflective polarizing film and the display. The advantage of a diffusion layer that is neutral to infrared light is that it scatters backlight light but does not scatter infrared light. The latter is particularly advantageous for infrared light photography using an infrared camera.

[0025] Thus, the present invention excels in providing a backlight unit that backlights the display brightly enough and with the required luminous intensity and uniformity, while allowing infrared light to reach the camera through the display without the image being blurred or blurred by the infrared light, but rather resulting in an infrared image that is sharp enough for editing or processing to extract the necessary information from the infrared image.

[0026] Similar to using the edge-based concept for backlighting a display with visible light, it can also be applied to providing infrared light: behind the infrared-transparent-reflective film there is a light guide that is illuminated from the side by the infrared light, refracting the infrared light and directing it back towards the infrared-transparent-reflective film.

[0027] In order to allow infrared light to reach the infrared photodiode array, for example as scattered light, it is advantageous to optically screen the infrared photodiode array with respect to the infrared light source or the above-mentioned infrared light guide.

[0028] In the variants of the invention described so far, no diffuser is provided in the space between the light exit surface of the light guide and the rear surface of the display. However, such a diffuser may be advantageous if only backlight light is to be diffused. Diffusing films are known in the prior art that scatter or transmit light without scattering, depending on the wavelength of the light. See, for example, https: / / onlinelibrary.wiley.com / doi / full / 10.1002 / adma.202105868.

[0029] It is advantageous to place a diffuser that functions according to such wavelengths in the space between the light exit surface of the light guide and the rear surface of the display, and this diffuser scatters the backlight and transmits the infrared light of the infrared light source without scattering it. This "neutral" diffuser for infrared light can be placed between the specular polarizing film and the display or light guide, if present.

[0030] The present invention will be described in detail below using the first modified embodiment of the present invention described above with reference to the drawings. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a diagram showing an example of an application of a display device according to one embodiment of the present invention. [Figure 2] FIG. 2 shows a (very schematic) first example of an optical layer stack for a display device. [Figure 3] FIG. 3 shows a (very schematic) second example of an optical layer stack for a display device. DETAILED DESCRIPTION OF THE INVENTION

[0032] 1 shows an example of an application of a display device 10 according to the invention with a rear-mounted infrared camera 12. In this embodiment, both are arranged in the vehicle's instrument panel 14, with the infrared camera 12 pointed towards the driver 16. The information extracted from the camera images is application-specific and is known in principle, and therefore does not need to be described in detail within the framework of the present invention.

[0033] FIG. 2 shows a first embodiment of the individual optical and electro-optical layers of display device 10 in a highly schematic manner, with the thicknesses of the individual layers and their spacing not being drawn to scale.

[0034] 2, the display device 10 comprises, for example, an LCD display 18 with a touch sensor system 20 arranged behind a cover glass 22. Thus, in this embodiment, the display device 10 is also used for inputting commands by touching a display surface 24.

[0035] A backlight unit 26 is provided behind the display 18 for backlighting the display 18 with visible light. For this purpose, the backlight unit 26 comprises a light guide 28 having a light exit surface 30 facing the display 18 and an opposite rear surface 32. The two or main surfaces of the light guide 28 are connected by a peripheral edge surface 34. A partial area of ​​this edge surface 34 is illuminated with backlight light 36, which is achieved by a plurality of backlight sources 38, for example in the form of LEDs. The light exit surface 30 is provided with an additional light guide film 40 having a minimal optical prism structure. This light guide film 40 is, for example, provided by the Finnish company Nanocomp Oy.

[0036] According to the present invention, no light diffusing elements, such as light diffusing films, are provided between the backlight unit 26 and the display 18, as these may be detrimental to infrared light, as will be further described below.

[0037] An infrared transmitting / reflecting film 42, which is also part of the backlight unit 26, is provided below the light guide 28, i.e., facing the rear surface 32. This reflective film reflects backlight toward the display 18.

[0038] An infrared light source 46, for example, an LED, is provided facing the rear surface 44 of the infrared transmitting and reflective film 42. In addition, an infrared camera 12, for example, an infrared photodiode array 48, is also provided facing the rear surface 44 of the infrared transmitting and reflective film 42.

[0039] It is also optional, but beneficial, to provide an infrared-neutral diffusing layer 59 between the light guide 28 and the (first) specular-reflective polarizer 50, or between the (first) specular-reflective polarizer 50 and the display 18, which scatters the backlight but transmits infrared light without scattering it. This homogenizes the backlighting of the display 18, which is advantageous for infrared imaging by the infrared camera 48, without scattering infrared light that reaches the area in front of the display 18 or in front of its cover glass 22, or that may be reflected therefrom.

[0040] A (first) specular-reflective polarizing film 50 is provided between the backlight unit 26 and the rear surface of the display 18, and reflects backlight light having a polarization direction that is offset from the polarization direction of a polarizing film 52 on the rear side of the display 18 (for clarity, the polarizing film on the front side of the display 18 is not shown) toward the infrared-transmitting-reflective film 42, where the backlight light is reflected back with its polarization direction changed again, as indicated by arrows 54, 56, and 58. In this way, substantially all of the backlight light from the backlight source 38 can also be used to illuminate the backside of the display 18.

[0041] The (first) specularly reflective polarizer 50 can also be used to reflect back infrared light from the infrared light source 46 whose polarization direction is shifted from that of the polarizer 52 on the rear side of the display. However, this requires an additional infrared reflector, not shown in FIG. 2.

[0042] Alternatively, a laser diode that emits only light in a polarization direction corresponding to the polarizing film 52 on the rear side of the display 18 can be used as the infrared light source.

[0043] In the "optical stack" embodiment of Figure 2, the light-guiding film 40 and the (first) specularly reflective polarizing film 50 are optional and both layers may be omitted.

[0044] The light from the infrared light source 46 passes through the backlight unit 26, then through the display, touch sensor system and cover glass, and reaches the area in front of the display device 10, where it is reflected by any monitoring or detection targets that may be present there, and is finally captured as a reflected image by the infrared camera 12.

[0045] It is also optional, but beneficial, to provide an infrared-neutral diffusing layer 59 between the light guide 28 and the (first) specular-reflective polarizer 50, or between the (first) specular-reflective polarizer 50 and the display 18, which scatters the backlight but transmits infrared light without scattering it. This homogenizes the backlighting of the display 18, which is advantageous for infrared imaging by the infrared camera 48, without scattering infrared light that reaches the area in front of the display 18 or in front of its cover glass 22, or that may be reflected therefrom.

[0046] 3 illustrates this case, where the optical stack of display device 10 includes a layer that reflects infrared light with a polarization direction offset from that of polarizing film 52 on the rear side of display 18 to enhance infrared light yield. Layers and elements in FIG. 3 that are the same as those in FIG. 2 are labeled with the same reference numerals in FIG. 3 as in FIG. 2.

[0047] If the polarization direction of the light from the infrared light source 46 does not match the rear polarizing film 52, it is reflected by the second specular polarizing film 60 and reaches, for example, an infrared reflecting film 62 located below the infrared light source 46. The infrared light reflected therefrom changes its polarization direction back to the direction of the second specular polarizing film 60, and if the polarization direction is correct, passes through the second specular polarizing film 60 (as indicated by arrows 64, 66, and 68 in FIG. 3 ) and reaches the area in front of the display device 10, where it is reflected back by the object to be monitored or detected and is captured by the infrared camera 12. [Explanation of symbols]

[0048] 10 Display device 12 Infrared camera 14 Instrument panel 16 Driver 18 Display 20 Touch Sensor System 22 Coverslip 24 Display surface 26 Backlight unit 28 Light guide 30 Light exit surface 32 Rear surface of light guide 34 Edge surface of light guide 36 Backlight 38 Backlight source 40 Light-guiding film 42 Infrared transmitting and reflective film 44 Rear surface of infrared transmission / reflection film 46 Infrared Light Source 48 infrared photodiode array 50 First specular reflective polarizing film 52 Polarizing film on the rear side of the display 54 Arrow 56 Arrow 58 Arrow 59 Infrared-neutral backlight diffusion layer 60 Second specular polarizing film 62 Infrared reflective film 64 Arrow 66 Arrow 68 Arrow

Claims

1. a display (18); A backlight unit (26); a reflective film (42); an infrared light source (46); an infrared photodiode array (48); a first specularly reflective polarizing film (50); An infrared camera-equipped vehicle display device comprising: the display (18) has a front surface with a display surface (24) and a rear surface; The backlight unit (26) has a backlight light source (38) and a light guide (28), the light guide (28) having a light exit surface (30), an opposite rear surface (32), and a peripheral edge surface (34) connecting the front surface to the rear surface (32); The backlight source (38) irradiates visible light onto at least a partial region of the edge surface (34), the space between the rear surface of the display (18) and the light exit surface (30) of the light guide (28) is free of any optical light diffusing elements; the reflective film (42) is disposed on or facing the rear surface of the light guide (28) and is configured to reflect backlight (36) and transmit infrared light; the reflective film (42) has a rear surface opposite the light guide (28); the infrared light source (46) and the infrared photodiode array (48) are all positioned facing the rear surface of the reflective film (42); the first specularly reflective polarizing film (50) is disposed on or opposite the rear surface of the display (18) and is configured to reflect visible backlight light (36) with a polarization that is offset from the polarization direction of the polarizing filter on the rear side of the display (18); The backlight (36) reflected by the specular reflective polarizing film (50) can be reflected back by the reflective film (42) after changing its polarization direction toward the specular reflective polarizing film (50); A display device in which infrared light from the infrared light source (46) passes through the reflective film (42), the light guide (28), the first specular reflective polarizing film (50), and the display (18) to reach an area in front of the display surface (24), and the infrared light from the infrared light source (46) reflected by an object that may be present in this area passes through the display (18), the first specular reflective polarizing film (50), the light guide (28), and the reflective film (42) to reach the infrared photodiode array (48).

2. 2. The display device according to claim 1, wherein the light guide (28) is configured as a light guide film (40).

3. 2. The display device according to claim 1, wherein the light guide (28) comprises a light guide film (40) and a light guide plate bonded together by an optical adhesive layer.

4. 4. The display device according to claim 1, wherein the first specularly reflective polarizing film (50) also reflects infrared light, the polarization of which is shifted from the polarization direction of the polarizing filter on the rear side of the display (18), and an infrared-reflecting film (62) is disposed below the infrared light source (46) to reflect the infrared light reflected by the first specularly reflective polarizing film (50) with a changed polarization direction.

5. 5. The display device according to claim 1, further comprising: a second specular reflective polarizing film (60) arranged on or opposite the rear surface of the reflective film (42); and an infrared reflective film (62) arranged below the infrared light source (46), wherein the second specular reflective polarizing film (60) is configured to reflect infrared light, the polarization of which is deviated from the polarization direction of the polarizing filter on the rear surface side of the display (18), and the infrared reflective film (62) is configured to reflect the infrared light reflected by the second specular reflective polarizing film (60) with a different polarization direction.

6. 6. The display device according to claim 1, wherein the infrared light source (46) emits near-infrared light, and the infrared photodiode array is a near-infrared photodiode array.

7. 7. A display device according to any one of claims 1 to 6, characterized in that the infrared photodiode array (48) is two-dimensional.

8. 8. The display device according to claim 1, further comprising a touch panel for manually inputting commands by touching the display surface (24) of the display (18).

9. 9. A display device according to any one of claims 1 to 8, comprising at least one optical lens arranged between the reflective film (42) and the infrared photodiode array (48).

10. 10. The display device according to claim 1, wherein a diffusion layer (59) for scattering backlight light is provided in a space between the light exit surface of the light guide (28) and the rear surface of the display (18), and the diffusion layer (59) transmits infrared light from the infrared light source (46) without scattering it.

11. 11. The display device of claim 10, wherein the diffusing layer (59) that is neutral to infrared light is arranged between the light guide (28) and the specular polarizing film (50) or between the specular polarizing film (50) and the display (18).

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