CN113383306A - Glass vehicle side window and divider window with active projection transparent screen - Google Patents

Abstract

The invention relates to a vehicle glazing and display system (1) comprising: a vehicle composite glazing unit (10; 10 '; 10 ' ') comprising a layer or surface (12 a; 12 b; 14) switchable between an active first state and a second state, which in the first state diffusely reflects incident light directed to the glazing unit from a first side of the vehicle composite glazing unit (10; 10 '; 10 ' ') to a second side of the vehicle composite glazing unit (10; 10 '; 10 ' '), and has a maximum gain in the range of 0.03 to 0.8, preferably between 0.3 and 0.6, and an intrinsic viewing angle α for real image elements generated in the glazing plane, which intrinsic viewing angle α is greater than 60 ° in a first direction in a reflective geometry and greater than 30 ° in a second direction perpendicular to the first direction, and which layer or surface is transparent in the second state; a projector (4) for projecting an image to a vehicle glazing unit to generate a real image in the plane of the glazing unit, and wherein the vehicle composite glazing unit (10; 10 '; 10 ' ') is a side or bay window (3); and a projector control unit for switching the projector and switching the layer or surface.

Description

Glass vehicle side window and divider window with active projection transparent screen

Technical Field

The present invention is in the field of displaying information on a glazing element of a vehicle. More specifically, the invention is in the automotive field, but is not limited to this field, but may be implemented in buses, railway vehicles, boats, aircraft or other vehicles. More particularly, the present invention relates to a vehicle glazing and display system comprising a vehicle composite glazing unit and a projector for projecting an image onto the glazing unit.

Background

In this field of technology, there are many patents or patent applications which are to some extent the background of the present invention.

US 7157133 discloses the basic concept of diffuse reflection with an embedded diffusing surface.

EP 2185966 discloses an element having a diffusing surface on which a reflective layer is deposited, entirely in an envelope (envelope) of the same refractive index as the diffusing element. This component is designated as a reflective working numerical aperture expander (numerical aperture expander) that appears functionally to be a diffuser and a transparent element in transmission. In this patent, the integration of such elements in a head-up display (HUD) projection system for generating a virtual image is mentioned.

US 8519362B 2 belonging to Saint-Gobain describes a HUD system assembled into a car (car). It is based on a laminated windscreen, wherein the HUD function comes from the layer of luminophore material. US 7230767B 2 describes a display system in a passenger glass pane (pane) that uses a light emitting material that projects an image to the driver. The image is a virtual image focused several meters from the eyes of the driver and from the windshield.

The preparation of HUD systems integrated into laminated glass panes is described in patent EP 2883693 owned by Saint-Gobain.

As regards the general concept of transparent glazing units with a certain degree of diffuse reflection, there are several patent publications by Saint-Gobain, such as EP 2670594, EP 2856256, EP 2856533, EP 2872328, EP 3063002, WO 2012104547, WO 2018015702 and FR 305417. In these patent documents it is inter alia disclosed that such diffusely reflecting glazing may comprise a rough inner surface and a coating provided thereon, and that such glazing may be used for OLED display solutions or for projection-based display solutions.

EP 3395908 a1 discloses a transmission type screen as a head-up display for automotive applications, wherein the screen is particle based.

In EP 3151062 a1, a video projection arrangement for integration into a vehicle window is presented, wherein the window comprises a reflective film applied on a surface having random irregularities.

JP 20169271 a discloses a video display system equipped with a detection device to detect movement of an observer, wherein the display system can be operated by the movement of the observer.

CN 203340200U and CN 208156364U disclose projection on PLDC devices.

DE 102004051607 a1 discloses a device and a method for displaying digital images onto geometric and photometric non-trivial surfaces. In particular, this document discloses projecting an image onto a non-planar surface using one or more projectors. In particular, the projection method comprises a calibration with a camera connected to a control system adapted to control said one or more projectors for adjusting the projection of the image for each displayed pixel of the image.

In US 2015358574 a1, a display is used to simulate an environment. The display may be positioned behind the wall opening to provide a window effect. The display terminates its active image area outside of the area from which the displayed content is viewable to create a seemingly infinite simulated environment.

The glazing of WO 2014096717 a1 comprises: a variable light diffusing system having an active element based layer switchable between a transparent state and a translucent state; at least two substrates disposed on either side of the variable light diffusing system; and at least one substrate comprising a patterned set of discrete diffusing elements.

US 2019025692 a1 discloses a transparent screen with an image projected from a projector. The transparent screen includes a display panel including: a diffusion film which diffuses projection light from the projector; and a colored film disposed farther from the projector than the diffuser film. The colored film has a variable transmittance.

Disclosure of Invention

It is an object of the present invention to provide a vehicle glazing and display system comprising a vehicle composite glazing unit suitable for a wide range of applications in future mobile solutions. More specifically, it is an object to provide a system which makes it possible to display rich content to substantially all persons using the vehicle, or at least to all those persons sitting or standing close to the respective glazing unit. Furthermore, there is a need for a solution that can be implemented largely on the basis of available technology and that is safe, reliable and cost-effective.

These and further objects are solved by a vehicle glazing and display system according to claim 1. Preferred embodiments of the invention are the subject of the respective dependent claims.

A vehicle glazing and display system according to the invention comprises: a vehicular composite glazing unit comprising a layer or surface that diffusely reflects incident light directed to the glazing unit from a first side of the vehicular composite glazing unit; and a projector for projecting an image onto the vehicle glazing unit to generate a real image in the plane of the glazing unit, wherein in particular the image is visible from the second side. Vehicle composite glazing units are used in transmission geometries. A vehicle glazing unit is a window (a divider window) in the interior of a vehicle or a side window or a rear window of a vehicle. The vehicle glazing and display system further includes a projector control unit for switching the vehicle compound switching unit and switching the projector. Vehicle glazings with display systems exhibit a maximum gain (also referred to as peak gain) in the range 0.03 to 0.8, preferably between 0.3 and 0.6. The intrinsic viewing angle α of the real image element generated in the plane of the glazing is greater than 40 °, preferably greater than 60 ° and more preferably greater than 70 ° or greater in a first direction, and greater than 20 °, preferably greater than 30 °, in a second direction perpendicular to the first direction. When these intrinsic viewing angles are used under standard environmental conditions within practical applications, an actual viewing angle of more than 60 °, preferably more than 90 ° and more preferably more than 120 ° or more in a first direction, and more than 30 °, preferably more than 45 ° in a second direction perpendicular to the first direction can be achieved. The actual viewing angle depends on both the lighting environment and the projector used. Nevertheless, the actual viewing angle is a common feature of screen specifications and may be determined for selected environmental conditions associated with a particular use case. For standard environmental conditions and projector specifications, the following values may be used:

exterior illuminance 2200 Lux (car exterior); interior illuminance 100 Lux (car interior); flux from projector 3500 lumens; projection surface: 16:9 screen, 9 ″ diagonal (20 cm wide); the actual viewing angle can then be extracted from the gain curve via a mathematical formula.

The actual viewing angle was studied based on the contrast of the screen. The contrast of the screen is generally defined as the luminance ratio between white and black pictures, wherein a minimum ratio of 4.5:1 (white picture: black picture) is considered necessary for information reading. Based on this, the actual viewing angle can be derived as the viewing angle θ within a position that achieves at least a minimum contrast of 4.5: 1.

The intrinsic viewing angle alpha of the projection screen is measured at the full width at half maximum (FWHM) of the peak near the gain maximum, regardless of the value of the observation angle theta at the center of the peak. The θ =0 ° reference used for gain curve measurement corresponds to the specular reflection direction. Therefore, the intrinsic viewing angle α is a property of the screen and does not depend on the ambient brightness and projector specifications. Therefore, since the maximum value of the gain curve often occurs at θ =0 °, the intrinsic viewing angle can also be defined in this case as twice the observation angle θ at the gain curve position where the half-peak width (half maximum width) of the gain curve is achieved.

The viewing angle (intrinsic and actual) should be maximized because a large viewing angle is necessary to ensure that all passengers of the vehicle can clearly see the projected content at the same time (independent of the seat occupied by the individual). However, at a given total screen reflectivity, a compromise between high peak gain and large viewing angle must be found. Vehicle glazings according to the present invention provide such a good compromise between peak gain and viewing angle.

In a preferred embodiment of the invention, the transparent screen of the vehicle glazing has a maximum gain between 0.1 and 0.8 and an actual viewing angle in one direction of more than 60 ° and in the other direction of more than 30 °. Typically, actual viewing angle values between 120 ° and 150 ° in the horizontal plane and between 30 and 180 ° in the vertical plane are derived. Within the intrinsic angle definition, intrinsic viewing angles are derived which are more than 40 °, more preferably more than 60 °, even more preferably between 70 ° and 150 ° in the horizontal plane, and between 20 ° and 180 °, preferably between 30 ° and 180 ° in the vertical plane. The vertical and horizontal planes are defined in the assembled condition of the vehicle glazing in the body of a passenger car.

Due to the mentioned actual and inherent viewing angle, all occupants in the vehicle can see the display content when the projector is on if the second side of the display is directed towards the occupant. If the vehicle glazing unit is a side window or a rear window, the display is directed to an observer outside the vehicle. According to a further aspect of the invention, the displayed image is a real image. A real image differs from a virtual image in terms of the focal plane. For virtual images, the focal plane is at a distance from the projection screen, e.g. 1 meter or up to several meters. In contrast, for real images, the focal plane is close to the screen. In sections, the focal plane of the real image according to the invention has a maximum distance of 30 cm from the projection screen.

When the projector is off and the glazing is switched to a transparent state, the glazing is optically similar to a conventional glazing, maintaining transparency with a slightly higher haze value. Typical haze values for such glazing, measured according to the standard ASTM D1003, are between 1% and 10%, preferably between 4.5% and 9.5%. Turbidity measures the fraction of transmitted light that deviates from a straight path at an angle of greater than 2.5 °. A high haze value corresponds to a loss of contrast of the image projected on the screen. In the given range of low haze values, good transparency of the screen is obtained. Switching active glazing changes the haze, while the transparency of the glazing remains unchanged. Thus, a uniform background is created to concentrate the observer on the projected image and create privacy back.

According to a further preferred aspect, the reflective layer or surface within the glazing unit has a visible light transmission in the transparent state of greater than 60%, preferably 70% or greater (e.g. 80% or greater). These transmittance values (also called the global luminescence transmittance T)_L) Quantifying the ability of a reflective layer or surface to transmit light having a wavelength between 400 nm and 800 nm, which is the spectral range visible to the human eye. For those measurements, it is not necessary to distinguish between diffuse and non-diffuse light. Nevertheless, the technique according to the invention is also applicable to glazings requiring lower light transmission.

To measure the gain and determine the appropriate viewing angle of the transparent screen, the brightness of the screen must be measured with the viewing angle with the projector illuminating the screen at normal incidence (0 °). The brightness of an ideal screen (referred to as the lambertian reference for Spectralon) was measured under the same conditions. An ideal screen is defined as a screen whose brightness does not depend on the projection or viewing angle and whose reflectivity is 100%. A lambertian reference screen is a surface that perfectly follows the lambertian cosine law, which states that: the luminous intensity observed from an ideal diffusely reflecting surface is proportional to the cosine of the angle between the direction of the incident light and the surface normal. The human eye can only recognize brightness, which is a measure of the luminous intensity per unit area of light traveling in a given direction and describes the amount of light reflected from a particular area. Therefore, a lambertian surface with ideal diffuse reflection is seen by the human eye as exhibiting the same brightness and brightness (brightness) regardless of the observation angle at which it is observed. An ideal lambertian diffuser can be obtained experimentally with a commercially available reference material called "Spectralon" made of sintered Polytetrafluoroethylene (PTFE). To retrieve the screen gain at each observation angle, a ratio between the screen brightness and the ideal screen brightness is calculated. The peak gain of the screen is the maximum gain value achievable by the screen. The maximum gain (also called peak gain) is often measured at 0 °, but some specially designed screens may have their maximum gain at other observation angles. It is noted that for a transparent screen, the values at 0 ° may not be measurable due to hot spots (specular reflection of the projector's light on the outer flat glazing surface), and are therefore extrapolated from the gain at small angles.

The preferred intrinsic viewing angle is defined in terms of gain as being within the full width half maximum of the gain curve (see fig. 3). This definition is an inherent definition. Gain represents the brightness of the projection screen relative to the brightness of an ideal screen (which is a perfect lambertian diffuser).

An alternative, more practical definition of viewing angle would be to define the actual viewing angle as one in which the contrast is below 4.5:1, but this definition depends on the viewing and lighting conditions and the projector. Thus, the intrinsic definition of viewing angle within the full width at half maximum of the gain curve is preferred. The gain curve may be determined as already described and has the shape of a gaussian curve, for example.

The inventors have detected that observation angles that are not just below half the intrinsic viewing angle (i.e., within the full width at half maximum of the gain curve) are suitable for practical applications of transparent screens. Sufficient observation results can be achieved at observation angles lower than half of the actual viewing angle in the range of 120 ° to 180 ° in the horizontal plane, preferably 120 ° to 150 ° in the horizontal plane, and 30 ° to 180 ° in the vertical plane.

To achieve sufficient contrast, the projector should have an output flux higher than 1000 lumens, better higher than 3000, ideally between 2000 and 10' 000. The optimum projector flux value must be selected depending on the environmental conditions.

The projection screen size may be large, depending on the projector brightness; position and screen gain and viewing angle. In operation of the system, typical image sizes are greater than 10 "(25 cm), typically between 10" (25 cm) and 60 "(152 cm), with between 30" (76 cm) and 50 "(127 cm) being preferred. Image size is measured as a diagonal dimension in inches, which is common in the field of screen technology. With the present technique, glazing units having a diagonal dimension of 2 m, preferably 1 m, are possible.

Since the available distance (projection distance) between the projector and the glazing in a direction orthogonal to the glass surface is typically between 2 cm and 60 cm, preferably between 7 cm and 40 cm, the preference is to use a short-throw (short-throw) projector. For short throw projectors, the throw ratio (size of the image/distance between the projector and the screen) is typically large. In short throw projectors, there is often folding optics (folding optics) so that the projector image can be displayed in a plane perpendicular to the output lens. The projector may be a projector having a conventional lamp, an LED, or a LASER as an illumination device.

In the present case, the projector is preferably arranged in a frame element or box of the vehicle, more preferably in the frame element and above, below or laterally to a side window or a partition window suitable as a composite glazing unit for a vehicle. Preferably, the projector is arranged in a frame element or box of the vehicle above or below the window, or the projector is arranged in the gap, in particular below the separating window. There may be two or more projectors arranged side by side and/or opposite each other. Where several projectors are projected on the same vehicle composite glazing unit, the projectors may be aligned to project a common single image. The number of projectors is selected depending on the size and geometry of the vehicle composite glazing unit. Instead of side windows, especially in the case of autonomous vehicles or public transport, rear windows can be used. The side, rear or divider windows extend vertically or are inclined from vertical by a small angle, for example 5 to 20 °.

If a position above the side, divider or rear windows is selected, it is less likely that a passenger inside the car will reach the projector and be injured or damage the projector. The above also applies to the arrangement between the driver's seat or another seat and the partition window. If the divider window is arranged behind the backrest of the seat, there is usually some space in which the projector can be arranged and which is not well accessible to the passengers. Even if the explanation is given by referring to the driver's seat, it may be another seat having a partition window arranged behind the backrest.

The above mentioned calibration is also necessary if the vehicle composite glazing unit is not flat. For calibration, the projector(s) is connected to a projector complex unit, which optionally comprises a camera.

By suitable arrangement of the respective (first and second side) surfaces of the glazing unit and in particular the diffuse reflective sheet coating or surface, respectively, the above-referenced generation of hot spots in the glazing unit can be suppressed to some extent. In a preferred embodiment, the hot spot is directed at least to the ground of the vehicle, where it does not annoy the occupants of the vehicle. In order to position the projector between the driver's seat and the partition window, hot spots may in principle occur at the roof above the driver's seat. However, by applying a dark fabric at the roof of the vehicle, the hot spot may not give glare to the driver. As an additional means for suppressing hot spots, at least one local blinder (blind) may be arranged in a suitably predefined position close to the output lens of the projector.

The image projected on the transparent screen is due to diffuse reflection. The reflection of a glazing is defined as the diffuse reflection when incident radiation having a given angle of incidence on the glazing is reflected in multiple directions. Specular reflection occurs when incident radiation on a glazing with a given angle of incidence is reflected at an angle of reflection equal to the angle of incidence. Likewise, transmission is defined as specular when incident radiation having a given angle of incidence is transmitted at a transmission angle equal to the angle of incidence. However, in order to maintain transparency across the glazing, the first and second sides of the glazing are flat and therefore cause specular reflection from the projector beam. For a side window or a rear window of the vehicle, the first side is defined as the inner side pointing towards the interior of the vehicle and the outer side is the second side. For a divider window, the first side is the side facing the projector. To achieve this experience, the light reaching the eyes of the vehicle occupants should be provided by "diffuse reflection" of the projected image on the glass. Specular reflections on the first and second sides of the glazing should be avoided. Specular reflections, also referred to as "hot spots," emit glaring light to an observer when directed at the observer. The direction of the hot spot can be obtained via the reflection law, which states that: the angle of reflection is equal to the angle of incidence. In order to avoid glaring light being emitted to the observer through the hot spot, the hot spot and the viewing direction of all passengers of the vehicle preferably exhibit an angular distance of at least 5 °, more preferably at least 10 °, most preferably at least 20 °.

With respect to the configuration of the vehicular composite glazing unit, according to a first aspect of the invention, the glazing unit comprises a first side glass or plastic pane, a second side glass or plastic pane, and a diffusely reflective plastic sheet laminated between the first side glass or plastic pane and the second side glass or plastic pane. The glazing is switchable between a first state in which incident light is diffusely reflected and a second state in which incident light is transmitted, comparable to a transparent glazing. The first state may be an active state and the second state may be a passive state, or vice versa. Thus, the glazing unit has a transparent and translucent state.

In embodiments of this aspect, the diffusely reflective sheet is an adhesive sheet or is embedded between two adhesive films or layers for bonding the first side glass or plastic pane to the second side glass or plastic pane.

In an embodiment, the diffuse reflective coating of the diffuse reflective plastic sheet or coated glass or plastic pane comprises nanoparticles or microparticles within a transparent substrate. More specifically, the nanoparticles or microparticles are or comprise liquid crystal particles, in particular polymer dispersed liquid crystals. The nanoparticles or microparticles may further comprise silica or a polymer. Metal or metal oxide particles may also be used. More specifically, the nanoparticles or microparticles may have a spherical shape and/or be transparent or translucent.

In particular, the diffusely reflective plastic sheet may be a PDLC (polymer dispersed liquid crystal) or inverse PDLC layer. The PDLC layer is particularly translucent if no current is applied, and transparent if current is applied. The reverse PDLC layer is particularly transparent if no current is applied, and translucent if a current is applied. Under comparable projection properties, the PDLC layer exhibits better contrast and higher brightness of the projected image than the inverse PDLC layer. However, the application of an inverted PDLC layer may be advantageous if the composite glazing unit for a vehicle is used only in special situations and a clear view through the composite glazing unit for a vehicle is desired in most cases. Conversely, the PDLC layer is advantageous if the vehicle composite glazing unit should be used primarily for projecting images, or if high contrast and/or brightness is desired.

In an embodiment, a vehicle composite glazing unit comprises: a first region comprising switchable glazing; and a second region, which is non-switchable. In particular, the first side glass or plastic pane and the second side glass or plastic pane extend throughout the first and second regions, while in the first region the diffuse reflective sheet is sandwiched between the first side glass or plastic pane and the second side glass or plastic pane, and a second polymer film having a similar or same thickness as the diffuse reflective sheet, in particular comprising Polyethylene (PE), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polyvinyl butyral (PVB), triacetyl cellulose (TAC) or polycarbonate, is sandwiched in the second region. The first and second areas may be optically distinguishable by the print frame.

Having a composition comprising titanium oxide TiO_xPlastic sheets with a diffuse reflective coating of particles or silver particles and plastic sheets with an organic diffuse reflective coating comprising cholesteric liquid crystals have proved to be particularly suitable for screen applications according to the invention. Most preferably, the diffusely reflective plastic sheet comprises liquid crystal particles aligned within a matrix.

Preferably, the diffuse reflective plastic sheet comprises a Polyethylene (PE), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polyvinyl butyral (PVB), triacetyl cellulose (TAC), or polycarbonate sheet. Such sheets are essentially commercially available or may be manufactured at the request of the manufacturer of the vehicle composite glazing unit, which is tailored to meet the specific optical requirements according to the invention.

The diffuse reflection plastic sheet has the advantages that: they can be inserted only at screen locations and are therefore easier to adjust.

The system of the invention brings significant advantages, at least in embodiments, which opens up a wide range of applications in future mobile concepts, including driver driven or autonomous cars, buses, trains or subway vehicles, boats, airplanes and helicopters.

Within the framework of this concept, users will require a wide range of information to be displayed to all of them (not just the driver) in a convenient and flexible way, and large-size displays implemented by means of the invention are very attractive in this respect. On the other hand, the glass window used for displaying the information is still completely transparent and may direct the projection of light to the outside of the vehicle-which may disturb outside persons or even be dangerous-outside the intended eye movement range of other road users.

The main application of the invention is to display content on glass in vehicles (also autonomous vehicles, buses, taxis, trains, tractors, airplanes). This may provide information internally to vehicle occupants and also externally to pedestrians, cyclists, bus and train occupants, other road users or to external users.

We can also think of infotainment systems integrated into glass to enable use in mixed reality environments: this means that the eyes of the occupant will see an image of the external environment combined with the image projected on the glazing. This is some kind of "augmented reality".

In the same way, security information, travel information, entertainment, video-like (like video) and advertising may be shown on the glass pane. This can result in the use of the glazing surface of the vehicle as an advertising surface while maintaining transparency.

Some security features can be introduced by this technique: the images are surprisingly visible from both the interior and exterior of the vehicle, and may display some information to the interior or exterior user, depending on the need. It is to be noted that such an image visible from outside the vehicle corresponds to diffuse light and therefore does not give off dazzling light to other road users and is therefore not in contradiction to the requirements of the inventors.

Likewise, external users may therefore also benefit from the presented system. For example, by displaying safety support features (flashing lights, etc.) on the windshield or side windows, awareness of external traffic participants may be enhanced. This may increase confidence in the autonomous vehicle for other road users or for occupants.

In the context of public transportation, we can think of information about routes, transportation purposes, next stops, final destinations on the windows of buses, trains, etc.

As such, the advertising industry would have a great interest in client targeting and context enhancement (context enhancement).

The present invention can be combined with other technologies such as, for example, HUD, any specific coating, Smart-WS, etc. It is possible to include this technology (transparent display in the glazing) in other more complex systems, such as integrating a camera for interaction with the vehicle occupants (e.g. skype conversation with the party projected on the glazing).

In the following, some preferred embodiments of the invention are described.

A vehicle glazing and display system comprising: a vehicle composite glazing unit comprising a layer or surface switchable between a first state and a second state, the layer or surface in the first state diffusely reflecting incident light directed to the glazing unit from a vehicle first side of the vehicle composite glazing unit (10, 10', 10 "), and having a maximum gain in the range 0.03 to 0.8, preferably between 0.3 and 0.6, and preferably a viewing angle for real image elements generated in the glazing plane, the viewing angle being greater than 60 °, preferably greater than 90 °, and more preferably 120 ° or greater in a first direction and greater than 30 °, preferably greater than 45 °, in a second direction perpendicular to the first direction, and the layer or surface being transparent in the second state; a projector for projecting an image onto a vehicle glazing unit to generate a real image in the plane of the glazing unit; and a projector control unit for switching the layer or surface and controlling the projector.

Preferably, the vehicle glazing and display system is adapted to view the projected image in a transmission geometry, i.e. from a second side of the vehicle composite glazing unit, the second side facing the first side of the vehicle composite glazing unit.

The first side of the vehicle composite glazing unit is preferably at the interior of the vehicle.

Preferably, the projector control unit is adapted to switch the vehicle composite glazing unit into the first state forcibly if the projector is open.

Preferably, the projector control unit is adapted to calibrate the projection of the image on a pixel basis. The projector control unit may include a camera.

Preferably, the glazing unit has a typical haze value in the range 1% to 6%, preferably between 2.5% and 4.5%, and/or the reflective layer or surface within the glazing unit has a visible light transmission of greater than 70%, preferably 80% or more.

Preferably, the vehicle glazing and display system is suitable as a side window or a divider window in a car, boat or airplane/helicopter.

Preferably, the vehicle glazing and display unit are adapted to be viewed from a first side of the vehicle.

Preferably, the projector is adapted to be arranged in a vehicle frame part of the vehicle, in particular above a side window separating the windows.

Preferably, the vehicle glazing and display system comprises at least a second projector adapted to be arranged beside or opposite the projector. The at least second projector is preferably connected to the projector control unit and adapted to be calibrated by the projector control unit.

Preferably, the projector control unit is connected or connectable to or comprises a camera.

Preferably, the at least one partial camouflage is arranged close to the output lens of the projector such that hot spots are avoided in the glazing plane of the glazing unit.

Preferably, the projector is adapted to provide an output flux of at least 1,000 lumens, preferably 3000 lumens or more.

Preferably, the vehicle glazing and display system is adapted to generate, in its assembled state, a real image in the glazing plane having a horizontal extension of at least 25 cm, preferably between 40 cm and 200 cm, preferably between 50 cm and 150 cm.

Preferably, the glazing unit comprises a first side glass or plastic pane, a second side glass or plastic pane, and a diffusely reflective plastic sheet laminated between the first side glass or plastic pane and the second side glass or plastic pane.

Preferably, the diffusely reflective sheet is an adhesive sheet or is embedded between two adhesive films or layers for bonding the first side glass or plastic pane to the second side glass or plastic pane.

Preferably, the glazing unit comprises a first side glass or plastic pane, a second side glass or plastic pane, and an adhesive film or layer for bonding the first side glass or plastic pane to the second side glass or plastic pane, wherein the first side surface of the first side or second side glass or plastic pane, respectively, contacting the adhesive film or layer comprises the diffuse reflective coating.

Preferably, the diffuse reflective coating of the diffuse reflective plastic sheet or coated glass or plastic pane comprises nanoparticles or microparticles within a transparent substrate.

Preferably, the nano-or microparticles comprise liquid crystal particles, and optionally further comprise silica or a polymer.

Preferably, the diffusely reflective plastic sheet is a PDLC layer or an inverse PDLC layer.

Preferably, the nanoparticles or microparticles have a spherical shape and/or are transparent or translucent.

Preferably, the diffusely reflective plastic sheet comprises a PE, PET, TAC, PVB, PMMA or polycarbonate sheet.

Preferably, the glazing unit comprises a first switchable region and a second non-switchable region.

Preferably, the vehicle glazing and display system are integrated within the interior of the sedan.

Drawings

Embodiments and aspects of the invention are illustrated in the drawings. Shown in the drawings are:

figure 1 is a first schematic view of a first embodiment of a vehicle glazing and display system according to an embodiment of the invention,

figure 2 is a second schematic view of a vehicle glazing and display system according to an embodiment of the invention,

FIG. 3 is a diagram for explaining the definition of the term "gain" in the context of the present invention, an

Fig. 4A-4C are schematic cross-sectional illustrations of embodiments of a vehicle composite glazing unit.

Detailed Description

Fig. 1 and 2 show an exemplary arrangement of a vehicle glazing and display system 1 in a bus 2 for projecting an image onto a separating window 3 of the bus by means of a projector 4 arranged in the spacing between a driver's seat 5 and the separating window 3. The projector 4 is arranged at a first side of the partition window, while an observer 20 (in particular, an occupant of the vehicle) is located at a second side of the partition window. An image generated by the projector in the plane of the glazing is shown and designated by the numeral 6.

In an exemplary geometry, the projector may be a commercially available short throw projector having a brightness of 3500 lumens and a contrast ratio of 13'000:1 and arranged internally between the driver seat 5 and the divider window 3, about 20 cm below the window and a distance orthogonal to the window of about 20 cm.

Exemplary structures of the partition window 3 are: a stack of two clear glasses (clear glasses) in the non-projection area, the PVB layer being laminated in the middle; and a Polymer Dispersed Liquid Crystal (PDLC) sheet in the projection area, the PDLC sheet laminated between two transparent glass layers. The projected area and the non-projected area may be divided by a printed black frame.

In this embodiment, the screen has a width of 80 cm and a height of 100 cm. In the case presented, the viewing area has a height of only 40 cm, but may be higher.

In the present embodiment, it is also possible to observe the projected image from the seating position as well as from the standing position.

It is also possible to project the screen only on a part of the glass pane comprising the switchable area using optical elements that directly control the light from the source (projector) or change the characteristics of the projector. In particular, only at the inside of the thick black frame, the diffusive elastic sheet 14 (e.g. PDLC layer) is sandwiched between two glass panes. Thus, the region inside the frame is the first region. The area outside the frame is the second area in which the thermo-elastic interlayer 13 is sandwiched between the two panes of glass, wherein the thermo-elastic interlayer 13 and the diffusive elastic sheet 14 have the same thickness in order to avoid mechanical stresses. Layer stack examples are depicted in fig. 4A-C. The invention may include the use of a darker interlayer foil or any darker element that will help increase contrast by reducing transmission while maintaining transparency.

The required brightness and the flux of light to be transmitted by the projector vary depending on the projection direction.

If the system must be integrated in an existing bus, it is sometimes impossible to avoid hot spots due to packaging and space limitations, and it is therefore necessary to resort to other methods to avoid hot spots for passengers.

Since hot spots are caused by specular reflection of light projected by the projector and reaching the eyes of the occupant, one way to eliminate hot spots is to disturb some of the light from the projector, for example placing an opaque non-reflective barrier that partially reduces or captures the projection surface on the glass. Hot spots can also be avoided by reducing the image size, so that the angular area where (hit) specular reflection can be encountered by an observer can be reduced.

In an embodiment, the elimination of hot spots is performed by identifying the hot spot locations of all occupants, and then placing a non-reflective optical surface (a piece of dark paper or a piece of dark material) between the projector and the portion of the vehicle window where the hot spot occurs.

However, in the current position of the projector, it is not possible to send out glaring light to the driver or any seated or standing passenger, since the projector projects mainly in the back side of the driver towards the roof of the vehicle.

The image projected on the transparent screen is due to diffuse reflection. However, in order to maintain transparency across the glazing, the first side (face 4) and the ground side (face 1) of the glazing are smooth and therefore cause specular reflection from the projector beam. In this context, a smooth surface is a surface without 3-dimensional structuring. Of course, the second side pane and the first side pane exhibit a 3-dimensional curvature. To achieve this experience, the light reaching the eyes of the vehicle occupants should be given by "diffuse reflection" of the projected image on the glass, and specular reflection (on the first side (face 4) and second side (face 1) faces) of the glazing should be avoided. Depending on the embodiment of the transparent screen, the first side of the glazing (sides 2 and 3) may be textured or smooth, wherein the smooth surface induces specular reflection and the structured surface causes diffuse reflection (see the embodiments of fig. 4A, 4B and 4C).

In the depicted embodiment, by switching the PDLC layer to the first state (i.e., the translucent state) when the projector is turned on by the projector control unit (not shown), glare to the occupant is further avoided. By this safety feature, it is avoided to open the projector while the separate window is transparent.

Fig. 3 shows a diagram for explaining an important parameter "gain" with respect to a screen (e.g., the window 3 in fig. 1), which is referred to as further explained above. The gain measurement is performed using a luminance meter and a video projector. For a given angle of incidence of the projected light, the brightness was measured at various observation angles. The projection angle is set as close to 0 ° (orthogonal to the screen) as possible. When the projection angle is kept fixed, the gain depends only on the observation angle θ. Therefore, the luminance meter position is adjusted so that the luminance meter is aligned with the specular reflection when the observation angle is set to 0 ° in the horizontal plane; since the mirror direction is taken as a reference for the observation angle measurement, the observation angle is therefore indeed equal to 0 °. Brightness measurements (measured in the horizontal plane) are performed from 5 ° to 75 ° every five degrees in an unlit environment isolated from any light source other than the video projector. Spectralon measured under the same conditions was used to normalize the brightness measurements and extract the gain from them. The intrinsic viewing angle α can be derived from these measurements as the full width at half maximum of the gain curve and depicts an angular width that causes the gain to exceed half the peak gain.

Fig. 4A-4C illustrate an exemplary embodiment of a vehicle composite glazing unit (or a laminated glazing unit) according to the present invention.

Fig. 4A shows a glazing unit 10 of substantially conventional construction, i.e. consisting of a first side glass pane 11 and a second side glass pane 12 bonded together as a switchable diffusive elastic sheet 14 by means of an interlayer containing liquid crystal particles. The diffusive elastic sheet 14 is switchable between an active state and a passive state. The second side glass pane 12 includes a second side surface (also denoted as face I) and a first side surface (also denoted as face II). The second side glass may be transparent glass or colored glass, and the first side glass may be transparent glass or colored glass. The first side glass pane 11 also comprises a first side surface (face III) and a second side surface (face IV). In order to achieve a high transparency of the glazing in the transparent state, an index matching of the refractive index between the glass and the interlayer is necessary. The two dielectric materials should have substantially the same refractive index, or their refractive indices should be substantially equal, which is defined as the absolute value of the difference between their refractive indices at 550 nm being less than or equal to 0.15. Preferably, the absolute value of the difference in refractive index at 550 nm between the constituent materials of the two layers is less than 0.05, more preferably less than 0.015. This applies not only to the particular embodiment of fig. 4a with PVB as the interlayer and the structured glass surface as the diffusing layer, but also to other embodiments like this.

Fig. 4B shows a glazing unit 10' corresponding to a conventional laminated glazing unit comprising a first side glass pane 11 and a second side glass pane 12, and an interlayer joining the glass panes 11, 12 together. However, the intermediate layer 13 is a multilayer including: a first thermoplastic interlayer 13.1 (preferably a PVB sheet) and a second thermoplastic interlayer 13.2 (preferably a PVB sheet), and a diffusely reflective sheet 14, such as PET or PMMA, embedded between the two thermoplastic interlayers (PVB sheets).

The reflectivity of the sheet 14 is due to transparent or translucent nanoparticles or microparticles randomly distributed in the material of the sheet. These may be, in particular, liquid crystal particles, for example. In a modified embodiment, the sheet 14 may additionally have one surface thereof provided with nano-or microstructures, similar to the surface 12a of the second side glass pane 12 in fig. 3A, and also coated with a thin reflective coating as mentioned for the surface 12 a.

Fig. 4C shows a further exemplary laminated glazing unit 10 ″ comprising a first side glass pane 11 and a second side glass 12 laminated to each other by means of a thin PVB sheet as a thermoplastic interlayer 13. In this example, the first side surface 12a of the second side glass pane 12 has a diffuse reflective coating 12 b. Such a coating may comprise nanoparticles or microparticles, in particular liquid crystal particles, as mentioned above in relation to fig. 4B, in a transparent matrix.

Reference numerals

Vehicle glazing and display system

2 vehicle

3 vehicle window

4 projector

5 driver's seat

6 images on glazing units

10; 10'; 10 '' vehicle compound glass window unit

11 first side glass pane

12 second side glass pane

12a first side surface of a second side glass pane

12b coating on second side glass pane

13; 13.1, 13.2 thermoplastic interlayer (preferably, PVB sheet)

14 diffuse reflection sheet

15 reflective coating

20 observer

Claims (15)

1. A vehicle glazing and display system (1) comprising: a vehicle composite glazing unit (10; 10 '; 10 ' ') comprising a layer or surface (12 a; 12 b; 14) switchable between an active first state and a second state, the layer or surface diffusely reflects incident light directed to the glazing unit from a first side of the vehicular composite glazing unit (10; 10 '; 10' ') to a second side of the vehicular composite glazing unit (10; 10'; 10 '') in the first state, and has a maximum gain in the range of 0.03 to 0.8, preferably between 0.3 and 0.6, and a natural viewing angle alpha preferably for real image elements generated in the plane of the glazing, the intrinsic viewing angle a is greater than 60 ° in a first direction and greater than 30 ° in a second direction perpendicular to the first direction in a reflective geometry, and the layer or surface is transparent in the second state; a projector (4) for projecting an image to the vehicle glazing unit to generate a real image in the plane of the glazing unit, and wherein the vehicle composite glazing unit (10; 10 '; 10 ' ') is a side or divider glazing (3); and a projector control unit for switching the projector and the switching of the layer or surface.

2. Vehicle glazing and display system (1) according to claim 1, the glazing unit comprising an electrochromic or polymer dispersed liquid crystal layer.

3. Vehicle glazing and display system (1) according to claim 1 or 2, wherein the projector (4) is adapted to be arranged in a frame or compartment above or below a side window or above or below a divider window.

4. Vehicle glazing and display system (1) according to any of claims 1 to 3, wherein the projected distance as given by the direction orthogonal to the glass surface is between 2 cm and 60 cm.

5. Vehicle glazing and display system (1) according to any of the preceding claims, wherein the vehicle glazing and display system (1) comprises at least a second projector adapted to be arranged beside the projector (4) or opposite to the projector (4).

6. Vehicle glazing and display system (1) according to any of the preceding claims, wherein the projector (4) is adapted to provide an output flux of at least 1,000 lumens, preferably 3000 lumens or more.

7. Vehicle glazing and display system (1) according to any of the preceding claims, adapted to generate in its assembled state a real image in the glazing plane having a horizontal extension of at least 25 cm, preferably between 40 cm and 200 cm, preferably between 50 cm and 150 cm.

8. Vehicle glazing and display system (1) according to any of the preceding claims, wherein the vehicle composite glazing unit (10; 10'; 10 ") comprises a first side glass or plastic pane (11), a second side glass or plastic pane (12), and a diffusely reflective plastic sheet (14) laminated between the first and second side glass or plastic panes, wherein the diffusely reflective plastic sheet is switchable between a first state and a transparent second state.

9. Vehicle glazing and display system (1) according to claim 8, wherein the diffusely reflective sheet (14) is an adhesive sheet or is embedded between two adhesive films (13.1, 13.2) or layers for bonding the first side glass or plastic pane (11) to the second side glass or plastic pane (12).

10. Vehicle glazing and display system (1) according to claim 8 or 9, wherein the glazing unit comprises a first side glass or plastic pane (11), a second side glass or plastic pane (12), and an adhesive film (13) or layer for bonding the first side glass or plastic pane to the second side glass or plastic pane, wherein a first surface (12 a) of the first side or second side glass or plastic pane contacting the adhesive film or layer comprises a diffuse reflective coating (12 b) or is treated so that the surface is a diffuse reflector, respectively.

11. Vehicle glazing and display system (1) according to any of claims 8 to 10, wherein the diffusely reflective coating (12 b) of the diffusely reflective plastic sheet (14) or coated glass or plastic pane (12) comprises nano-or micro-particles within a transparent substrate.

12. Vehicle glazing and display system (1) according to claim 11, wherein the nano-or microparticles are silica or polymer or liquid crystal particles.

13. Vehicle glazing and display system (1) according to claim 12, wherein the nano-or microparticles have a spherical shape and/or are transparent or translucent.

14. Vehicle glazing and display system (1) according to any of claims 8 to 10, wherein one surface of the diffusely reflective plastic sheet (14) comprises random nano-or microstructures and in particular the other surface is polished.

15. The vehicle glazing and display system (1) according to any of claims 8, 9 or 10 to 14, wherein the diffusely reflective plastic sheet (14) comprises a PE, PET, TAC, PVB, PMMA or polycarbonate sheet.

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