Screen and its control method

Abstract

TITLE: Screen and its control method. Screen (100) comprising: - a first image-generating layer (105) illuminated by a first surface light guide (115) and a second surface light guide (155) to illuminate the image-generating layer (105) with parallel or stacked images, - a first lighting system (120) coupled to the first guide (115) and comprising light sources (125) arranged to emit in a first direction (130), and a second lighting system (160) coupled to the second guide (155) and comprising light sources (165) arranged in rows to emit in a second lighting direction (170), different from the first direction (130). Figure 1

Description

Title of the invention: Screen and its control method FIELD OF INVENTION

[0001] The present invention relates to a screen as well as to a vehicle equipped with such a screen and a method of controlling the screen as well as a control device and a computer program for implementing the method. STATE OF THE ART

[0002] The vehicles are equipped with screens which display different images of information for the driver and, in addition or alternatively, for the passenger.

[0003] DESCRIPTION AND ADVANTAGES OF THE INVENTION

[0004] The present invention relates to a screen, characterized in that it comprises: a first image-generating layer for generating an image to be emitted, a first surface-shaped light guide for illuminating the image-generating layer, a second surface-shaped light guide for illuminating the image-generating layer, the first light guide and the second light guide being parallel to each other and / or being stacked, at least a first lighting installation which is or can be coupled to the first light guide and comprises a set of light sources juxtaposed in rows to emit light in a first direction of illumination, the first lighting installation being practically parallel to one side of the first light guide;at least one second lighting installation which is or can be coupled to the second light guide and comprises a set of light sources arranged in rows to emit light in a second direction of lighting, in particular the second direction of lighting being different from the first direction of lighting.

[0005] The screen according to the invention reduces power consumption and thus cost, and also increases the screen's thermal resistance. At the same time, it allows for a different distribution of brightness during image generation, providing various viewing modes that reduce driver distraction and thus increase road safety.

[0006] As stated, the invention relates to a screen comprising an image-generating layer for generating an image to be displayed, as well as a first surface-shaped light guide for illuminating the image-generating layer and a second surface-shaped light guide for illuminating the image-generating layer. The first and second light guides are parallel and stacked. The screen comprises a first lighting system coupled to the first light guide and several light sources juxtaposed in rows to emit light in a First lighting direction. The first lighting installation is installed almost parallel to one side of the first light guide.

[0007] The screen also includes a second lighting installation coupled to a second light guide and comprising an array of light sources or light sources arranged in rows to emit light in the second lighting direction. According to the invention, the second lighting direction differs from the first lighting direction.

[0008] For example, the screen may be a device installed in a vehicle as a co-pilot display, also called a co-pilot display (CPD), with switched backlighting. The image-generating layer includes, for example, a transmission image generator, such as an LCD liquid crystal display. The LCD display may have backlighting with a first and a second surface light guide. The light guides are each coupled to a direction of illumination such that the power supply of the lighting system ensures lateral coupling within the light guide and its distribution across the surface. The first and second directions of illumination may also be called the first and second LED strips and are controlled independently of each other.The lighting directions can be provided along opposite sides of the screen; for example, the first lighting installation can, according to a particularly advantageous embodiment, be along one long side and the second lighting installation along the short side of the screen so that the light sources are distinguished from each other by their lighting directions.

[0009] To perform the functions of the devices described above, the number and position of the lighting system(s) used to illuminate the first light guide are generally of little importance, so other systems can also be used. However, an important factor is the position of the second lighting system, which must always be along the transverse side to generate a lighting direction that extends practically in the direction of the long side of the screen. For example, the long side is the side corresponding to the (x) axis, and the transverse side is the side corresponding to the (y) axis.This different arrangement of lighting directions relative to the screen, as well as the different arrangement of light guides in the layered structure of the screen, allows the screen to operate advantageously in different switching states that differ in the distribution of brightness generating an image on the image-generating layer.

[0010] By way of example, the screen is designed to have a limited viewing mode, powered only by the first lighting installation; this mode can also be called "limited viewing mode" or "first viewing mode", as opposed to a first switching state or private mode. In this viewing mode Limited by the concentration of light emission, the displayed image will only be visible from a viewing angle at which the observer's gaze must be as parallel as possible to the direction normal to the screen surface. Such a mode is advantageous, for example, if the screen displays sensitive data, such as private banking information that should not be seen by others. As another example, if the observers are the driver and passenger of a vehicle, the limited viewing mode can block distracting image content, such as moving images, thus increasing traffic safety.

[0011] Conversely, by activating the first lighting system in combination with the second lighting system, a free-viewing mode is established. This mode can also be called "free-viewing mode" or "second viewing mode"; for example, a second switching state or public mode can be set. In this free-viewing mode, the image will be viewed from a wide viewing angle, visible to several observers. An appropriate ratio of the power of the first LED strip and the second LED strip can be set so that the brightness requirements can be met as effectively as possible in the different viewing areas; at the same time, the brightness of the asymmetrical light distribution relative to the long side of the screen is limited in the viewing areas not concerned, for example, towards the side windows of the vehicle.

[0012] In a third switching state, by activating only the second lighting system, a third limited viewing mode can be set. This mode differs from the first limited viewing mode in that the displayed image will only be visible from a first viewing angle, oriented laterally to the long side of the screen, and the displayed image will not be visible, or only faintly visible, in other viewing directions, for example, parallel to the normals to the surface and in the direction of a second, lateral viewing direction, opposite to the first lateral viewing direction. This situation can also be called "economy mode" or "driver mode" and is set, for example, if the display is to be limited to an observer positioned to the side, for example, the driver, while the image for the passenger's viewing direction and, for example, towards the side windows of the vehicle, will be blocked.

[0013] Overall, the described arrangement of the lighting installations advantageously reduces the screen's power consumption by always optimally adjusting the screen's light output according to the application. Furthermore, power consumption can be reduced by eliminating an appropriate overlap of the light output from the two light guides to avoid excessive brightness at undesired viewing angles in the vehicle, particularly in Directions oriented towards the side windows. Thanks to reduced power consumption, the brightness requirements for these characteristic viewing directions can be met with a smaller number of LEDs, thus lowering costs. Furthermore, the reduced power consumption decreases the risk of component overheating, meaning that a reduction in power consumption for the rear lighting will only be necessary in high ambient temperatures. This ensures, for example, that image content remains clearly legible even in high ambient temperatures inside the vehicle, despite bright ambient light. In particular, the advantageous power consumption will also increase the operating range of an electric vehicle. Moreover, the assembly describes lighting installations that enhance road safety because, in limited vision mode, the image will be blocked for the driver and will not risk distracting them.Furthermore, in all three viewing modes described, increasing screen quality in a vehicle environment eliminates annoying optical reflections of the image on the side windows or in the side mirrors.

[0014] In one embodiment, the screen includes a third lighting system. This third lighting system, which is or can be coupled to the second light guide, comprises a set of adjacent light sources connected in series to emit light in a direction opposite to the second direction. Thus, the third lighting system can be located, in particular, on the side of the second light guide opposite to the second lighting system. For example, the third lighting system can be located on the side of the screen, opposite the second lighting system, and operate independently or in combination with the first and second lighting systems. The optional extension of the mounting by the third lighting system allows for advantageous adjustment of both a symmetrical and asymmetrical distribution of brightness, depending on the application requirements.For the manufacturer, for example, for marketing reasons, this design might be a criterion because the image content for the passenger side can be seen from the outside (showroom effect). Similarly, in an unspecified application, when the driver approaches, and also or alternatively, the passengers, the vehicle is presented with image content visible from the outside. Thus, the third LED strip could be switched off in adjustment mode or operate only at reduced power.

[0015] According to another embodiment, the first lighting installation is designed to emit light in the first lighting direction at an angle of less than 150° to the second lighting direction, in particular at an angle of approximately 90° to the second lighting direction. For example, the first lighting installation will be provided along a long side and the second lighting installation along one transverse side of the screen, at a right angle to the longer side. Alternatively, the first lighting setup is designed so that the first lighting direction is at an angle between 150° and 210° to the second lighting direction, specifically, at an angle of at least approximately 180° to the second lighting direction. The first lighting direction in this example can be opposite to the second lighting direction.

[0016] The first lighting installation can be installed along one transverse side and the second lighting installation along the second transverse side of the screen, parallel to the first transverse side. The arrangement, with the first LED strip on one of the long sides in the (x) direction and the second LED strip on the transverse side in the (y) direction, is an alternative to installing both LED strips on the same side, one above the other. This arrangement is advantageous for improving the overall thermal performance by reducing the risk of hot spots. In other words, the heat output will be better distributed throughout the space, meaning that the power density per unit length will be reduced in public settings by this distributed arrangement.

[0017] According to another embodiment, the screen includes a reflective layer for reflecting light rays, and the reflective layer is provided on the side of the first light guide opposite the second light guide. For example, the reflective layer may be a surface reflector, for example, a reflective film, provided on the underside of the screen. The reflective layer can advantageously reflect the light distributed by the light guides and deflect it towards the image-generating layer.

[0018] According to another embodiment, the screen has a diffusion layer to distribute the light rays homogeneously. The diffusion layer is installed between the first and second light guides, and in particular, the diffusion layer is applied by bonding to the back and thus forms part of a first prismatic layer. For example, the diffusion layer is a diffusion layer of the sheet type or a diffusing film provided, for example, on the side of the first light guide opposite the reflective layer. Advantageously, the light rays emitted by the light guide will be distributed homogeneously over the surface by means of the diffusion layer, which acts as a diffuser; this will result in a surface light source that is uniformly illuminated.

[0019] According to another development, the screen has a first prismatic layer and a second prismatic layer for directing the light rays; the first prismatic layer and the second prismatic layer are installed between the first light guide and the second light guide. For example, the prismatic layers can The prismatic layers are installed between a first and a second light guide. The two prisms can be installed with a crossed orientation. The second prismatic layer can be at an angle of at least 25° to the longitudinal axis of the prisms, preferably with a 90° crossing angle to the first prismatic layer. Advantageously, the use of prismatic layers allows for a strong concentration of the light rays emitted by the first light guide relative to the normal to the surface, that is, parallel to the (z) direction of the installation.

[0020] According to another embodiment, the screen comprises at least one lamellar layer or several lamellar layers essentially oriented parallel to each other in the passing direction to concentrate the light rays and, in addition or alternatively, absorb diffuse radiation. The lamellar layer is installed between the first light guide and the second light guide. The lamellar layer is, for example, a lamellar film, for example, a light control film (LCF film), which is installed between the prismatic layers and the second light guide. The lamellar films advantageously allow for a more concentrated focus of the light rays by absorbing diffuse light. These light beams can then pass through the second light guide and further through the LCD panel with an unchanged direction.

[0021] In principle, other construction and application variants can also be envisaged, other backlit stacking components which separately or in combination advantageously ensure the same functions and allow a higher concentration of light rays from the lower area of ​​the rear lighting before passing through the second light guide and the other components installed on top.

[0022] The invention also relates to a vehicle with a variant of the screen described above. The screen can be installed on the passenger side, and the second lighting installation can be on the side of the screen opposite the driver's side. For example, the screen is integrated into the vehicle's dashboard. The visibility of the displayed image content can be modulated according to different switching states, which are determined by powering the screen in a single lighting direction or by powering both lighting directions in combination.

[0023] Advantageously, in the first application case, the image content will be blocked for the driver while the co-pilot or passenger will receive the image. This may be necessary, for example, if critical video information, such as moving images like movies, is displayed on the screen, so as not to distract the driver.

[0024] According to a second application, the screen can also display non-critical image content, for example, non-distracting status images, from various viewing angles, even if this is not permitted by law, regulations, or standards. Mounting the second lighting system on the side of the screen opposite the driver's side, in conjunction with a suitable, but not detailed, design of the light guide optics, also advantageously allows for asymmetrical image generation. The expression "opposite the driver's side" means, for example, that the correct lighting must be applied so that the second row of LEDs illuminates the upper light guide on the right-hand side (i.e., near the side of the window) relative to the driver's left side of the vehicle.This allows for the generation of a visible image for both the driver and passenger, while simultaneously minimizing the risk of reflection of the displayed image content through the vehicle's side window. This is particularly desirable in low-light conditions, such as during nighttime driving.

[0025] The invention also relates to a method for controlling a variant of the screen described above, the method comprising a single control step of the first lighting system to limit the distribution of brightness to the image-generating layer and thus provide a limited viewing mode. Alternatively, in the unilateral control step, only the second lighting system will be controlled to limit the distribution of brightness to the image-generating layer and generate a second limited viewing mode that differs from the first limited viewing mode. In addition, or alternatively, the method comprises a simultaneous control step of the first and second lighting systems to extend the distribution of brightness to the image-generating layer and thus provide a free viewing mode.

[0026] For example, in the unilateral, exclusive control step, the first lighting system is activated. Thus, the light from the first light guide will be distributed across the surface and reflected by a reflective layer to be guided exclusively towards the image-generating layer. The light rays can, for example, be distributed homogeneously across the surface using a diffuser and directed in all directions, i.e., diffusely.

[0027] After other prismatic films oriented, for example, crosswise, the light rays can be concentrated strongly with respect to a normal to the surface. A lamellar layer can concentrate the light rays even more strongly because the diffuse light will be absorbed. In the ideal case, a light beam will be obtained in the direction of the normal to the surface with the suppression of diffuse light as much as possible. This light beam can then pass through the second The light guide is in its non-functional switching state, followed by the image-generating layer. Through concentrated light emission, the displayed image will only be visible from a viewing angle whose direction of vision is as parallel as possible to the normal to the screen surface.

[0028] Unilateral control of the second lighting system, on the other hand, generates an even more limited viewing mode, such that, for example, the displayed image will be practically only perceptible within a viewing angle corresponding to the driver's direction, and at the same time the screen brightness will be severely limited in the direction perpendicular to the surface and at a viewing angle towards the side windows. This allows for a further asymmetrical distribution of brightness, which can be optimized by appropriately adjusting the brightness demand from the driver's viewing angle, while the unaffected viewing directions will remain practically unlit.

[0029] In the simultaneous control step, a free-viewing mode is generated in which the displayed image is visible over a wide viewing angle and thus to several people. To achieve this, the first and second lighting systems are powered simultaneously, and the power output is adjusted accordingly to meet the brightness requirements in the different viewing zones as effectively as possible. This method allows the light output of the first and second light guides to be advantageously combined through the principle of superposition. In short, an asymmetrical distribution of brightness is achieved, adapted to the actual brightness requirement.

[0030] According to one embodiment, the method includes a step of controlling a third lighting installation. This third lighting installation can be controlled simultaneously with the first lighting installation and in addition to, or alternatively with, the second lighting installation to extend the distribution of brightness to the image-generating layer and increase the free-vision mode.

[0031] For example, the third lighting installation can be provided on the opposite side to the second lighting installation. By controlling the second and third lighting installations, a symmetrical or asymmetrical distribution of brightness is advantageously achieved, which allows the generated image to be seen optimally from different viewing angles or from all sides of the screen.

[0032] This method can be implemented, for example, in the form of a program or a circuit or in the mixed form of a program and a circuit, for example, by a control device.

[0033] The invention as presented also relates to a control device designed to perform all the steps of a variant of this process in suitable installations. This variant embodiment of the invention is in the form of a device for The command allows the invention to solve the problem posed quickly and efficiently.

[0034] The control device comprises, for this purpose, at least one processing unit for handling signals or data, at least one memory unit for storing signals or data, at least one interface to a sensor or actuator for storing sensor signals or for transmitting control signals to the actuator, and / or at least one communication interface for storing and transmitting data that will be integrated into a communication protocol. The processing unit comprises, for example, a signal processor, a microcontroller, or a similar means, and includes Flash memory, EEPROM memory, or a magnetic memory unit. The communication interface is designed to store or transmit data via a wireless and / or wired connection; the communication interface may also transmit or receive data via the wired connection.This data is electrical or optical data originating from or emitted by a corresponding data transmission line.

[0035] A control device is an electrical device according to the invention that processes sensor signals and generates control or data signals based on the sensor signals. The control device has an interface in the form of a circuit or a program. In the case of a circuit embodiment, the interface is, for example, part of an ASIC system that incorporates the various functions of the control device. It is also possible to have dedicated interfaces with integrated switching circuits and formed at least in part from discrete components. In the case of a program embodiment, the interfaces are program modules, for example, in the microcontroller, alongside other program modules.

[0036] A variant of the screen as presented above includes a control device. This combination has the advantage of optimally combining all the advantages described above.

[0037] The invention also relates to a computer program product or simply a computer program comprising program code recorded on a machine-readable medium or a memory medium such as a semiconductor memory, a hard disk or an optical memory to enable the execution, application and control of the steps of the process according to any of the embodiments presented above, in particular when the program product or, more simply, the program is executed by a computer. Brief description of the drawings

[0038] The present invention will be described in more detail below with the aid of embodiment examples shown in the accompanying drawings in which the various identical or similar elements bear the same reference numerals, as follows:

[0039] [Fig-1] Diagram of an example of a screen implementation,

[0040] [Fig.2] Diagram of an example of a screen brightness curve,

[0041] [Fig.3] Schematic top view of a screen with a third installation lighting according to an example of implementation,

[0042] [Fig.4] Diagram of a brightness curve of an example of an embodiment of screen,

[0043] [Fig.5] Schematic side view of an example of a vehicle equipped with a screen,

[0044] [Fig.6] Schematic top view of an example embodiment of a vehicle equipped from a screen,

[0045] [Fig.7] Flowchart of a method for controlling a screen according to an example of realization,

[0046] [Fig.8] Flowchart of a method for controlling a screen of an example of realization,

[0047] [Fig.9] Schematic cross-sectional view of another example of a screen embodiment,

[0048] [Fig. 10] diagram of the brightness curve of an example embodiment of a screen.

[0049] DESCRIPTION OF EMBODIMENT METHODS OF THE INVENTION

[0050] Figure 1 shows a screen 100 of an embodiment. In this embodiment, the screen has a rectangular shape and comprises a stack of surface layers. By way of example only, the stack in this representation has an image-generating layer 105 for generating an image to be displayed. This image-generating layer 105 of the example embodiment is in the form of an LCD liquid crystal panel.

[0051] The lower side of the screen 100 according to the figure includes, by way of example only, a reflective layer 110 for reflecting light rays; this layer is made, by way of example only, of a reflective film. The reflective film in this embodiment reflects light rays arriving through the reflective layer 110 next to the first light guide 115 to illuminate the image-generating layer 105. The first light guide 115 is coupled to a first lighting system 120 to provide the light. The lighting system 120 comprises a set of light sources, or light sources, arranged in series 125 to emit light in a first direction of radiation 130. The light sources 125 are implemented, by way of example only, as LEDs; therefore, the first lighting system 120 is called the first light guide 1. LEDs. The first lighting installation 120 is parallel to the long side of the first light guide 115.

[0052] In this embodiment, the screen 100 also includes a diffusion layer 135 for homogeneously distributing the light rays, which are represented, for illustrative purposes only, as a diffusion film and are also called diffusers. The screen in this embodiment has a first prismatic layer 140 and a second prismatic layer 145 for guiding the light rays; these are represented, for illustrative purposes only, as prismatic films. The second prismatic layer 145 in this embodiment is arranged at an angle, given only by way of example, of 90° to the longitudinal axis of the prisms in the first prismatic layer 140.

[0053] In the figure, the diffusion layer 135, the first prismatic layer 140, and the second prismatic layer 145 are positioned above the first light guide 115. In this embodiment, there is a lamellar layer 150 above the second prismatic layer 145. The lamellar layer 150 is used only as an example, as a light control film (LCF film) to concentrate the light rays and absorb the diffuse light rays. In this other embodiment, the lamellar layer may also consist of several superimposed lamellar films oriented primarily parallel to the passing direction.

[0054] In this embodiment, a second surface light guide 155 is located between the lamellar layer 150 and the image-generating layer 105 to illuminate the image-generating layer 105. The second light guide 155 is coupled to a second lighting system 160 similar to the first lighting system 120, with a set of juxtaposed light sources arranged in rows 165, implemented, for example, in the form of LEDs. Accordingly, the second lighting system is thus called the second LED strip. The light sources 165 of the second lighting system 160 are designed to emit light rays in a second radiation direction 170; this second radiation direction 170 differs from the first radiation direction 130.Thus, in this example, the first ray beam direction 130 forms an angle of less than 90° with the second ray beam (or lighting) direction 170. In other words, the first LED strip is positioned on one of the long sides in the (x) direction, while the second LED strip is positioned on the transverse side of the screen 100 in the (y) direction. The two lighting systems 120 and 160 are controlled both independently and simultaneously or in combination.

[0055] The single (unilateral) power supply of the first lighting system 120 couple and distributes the light laterally across the surface in the first light guide 115. The light rays are distributed homogeneously across the surface by the diffuser, thus corresponding to a homogeneous, illuminated surface light source. The light rays are then oriented in all directions, i.e., they are diffused. Furthermore, after passing through the prismatic film, the light rays are already highly concentrated in the direction normal to the surface, i.e., parallel to the (z) direction of the system. The lamellar film then concentrates the light rays even more strongly by absorbing the diffuse light. This results in a light beam in the direction normal to the surface with the suppression of the diffuse light component.After this light beam passes through the second light guide 155, which is neutral for this switching state, the image-generating layer 105 is illuminated and generates an image. The concentrated light emission produces an image that is only visible within a very limited viewing angle when the view is practically parallel to the normal to the screen surface. This results in a very limited viewing mode, which can also be called the "first switching state" or "private mode".

[0056] By powering the first lighting system 120 in combination with the second lighting system 160, a free-viewing mode is generated, which can also be called the "second switching state" or "public mode." To achieve this free-viewing mode, the two LED strips 1 and 2 are powered in combination with an appropriate, adjustable ratio between the power P_1 of the first LED strip and the power P_2 of the second LED strip to meet the brightness requirements in the different viewing areas as closely as possible. The light emission from the first and second light guides 115, 155 is combined by the principle of superposition. In short, an asymmetrical brightness curve is obtained, adapted to the actual brightness demand in the image-generating layer 105.

[0057] The exclusive (unilateral) power supply of the second lighting system 160, on the other hand, generates another limited vision mode which is called the "third switching state" or "driver mode" or "economy mode". To obtain this second limited vision mode, the second LED strip is powered and an appropriate power P_2 is set for the power supply of the second LED strip to meet as closely as possible the brightness requirements in the lateral vision zones and to block the normal mode on the surface. This results in a brightness curve adapted to the actual brightness demand, which is asymmetrical in the image-generating layer 105.

[0058] Figure 2 shows diagram 200 of the brightness curve of an example embodiment of a screen like the one described in the preceding figure. The intermediate curve corresponds to a brightness curve 205, symmetrical in the limited viewing mode of the screen; in this mode, only the light emanating from the first light guide is present. The light is concentrated from a median viewing area A+ of the screen so that the generated image is visible within a viewing angle of an observer oriented along the normal to the screen surface. The light emitted solely by the second light guide generates an asymmetrical brightness curve 210, of which, by way of example, the left side of the screen is represented here by viewing areas A and B. The combined operation of the two lighting systems correspondingly generates an asymmetrical brightness curve 215 with an image generated in viewing areas A+, A, and B.

[0059] The dashed section schematically represents, and only as an example, the required brightness or luminance in specific viewing ranges. As an example only, as shown, L(A+)>=L(A)>L(B); however, other brightness profiles can, in principle, be selected. As in the combined mode, brightness levels are primarily adjusted in ranges A and B, mainly independently of the brightness in range A+. This embodiment also allows for compensating the perceived brightness for the driver's vision across multiple juxtaposed displays (e.g., on the central display intended for the driver and passenger) by adjusting an appropriate power level to compensate, respectively and simultaneously, for a generally higher brightness for the passenger, optimized in range A+.

[0060] The viewing ranges A+, A, and B are generally defined as viewing angle ranges in a spherical polar coordinate system and are used to specify the brightness emitted by the screen in this viewing detail in space. For simplicity, and only as an example, in the transformed Cartesian diagram 200, we only have the horizontal limitation of the viewing range (x-axis) in a horizontal cutting plane (for example, for a vertical angle of 0°), although the visibility range is also defined by a vertical component.

[0061] Figure 3 is a schematic top view of an exemplary embodiment of a screen 100 comprising a third lighting system 300. The screen 100 thus represented corresponds to or is similar to the screen described in Figures 1 and 3, with the difference that the screen 100 of this exemplary embodiment comprises a third lighting system 300. The third lighting system 300 is installed solely as an example, on the side of the second light guide, opposite the second lighting system 160, and it can be coupled to the second light guide. The third lighting system 300 is congruent with the first and The second lighting system 120, 160 consists of a set of light sources 305 arranged in a row to emit light in a third radiation direction 310 opposite to the second radiation direction 165. In this embodiment, the screen 100 also includes a control unit 320 to independently control the lighting systems 120, 160, and 300 and generate an image with different brightness curves. Thus, by controlling the second and third lighting systems 160 and 300, which are opposite each other, in combination with the lighting system 120, a symmetrical or asymmetrical brightness curve can be generated.

[0062] Figure 4 shows a graph 400 of an example of an embodiment of the brightness curve of a screen like the one described using Figure 3. This graph also shows the brightness curve 410 for controlling the third lighting system. The brightness curve 410 corresponds, by way of example, only practically to the symmetrical plane brightness curve 210 of the second lighting system. The third lighting system can also be controlled to have a brightness curve 410 with a greater or lesser amplitude than that of the brightness curve 210. In the diagram shown, this results from the simultaneous control of the first, second, and third lighting systems with a brightness curve 415 shown only as an example, so that the image on the screen is visible from all sides.According to another example, with appropriate control, an asymmetrical brightness curve will be obtained.

[0063] Fig. 5 is a schematic side view of an example of a vehicle 500 equipped with a screen 100. The screen 100 shown corresponds to or is close to the screen described in Figures 1 and 3. By way of example only, the screen 100 is integrated into the dashboard 505 of the vehicle 500.

[0064] Figure 6 shows a schematic top view of an example vehicle 500 equipped with a screen 100. The vehicle 500 as shown corresponds to or is analogous to the vehicle described in Figure 5, and the screen 100 corresponds to or is analogous to the screen described with reference to Figures 1, 3, and 5. The vehicle in this example embodiment is divided into a driver's side 600 on the left side of the figure and a passenger's side 605 on the right side. The screen 100 in this example embodiment is installed on the passenger side 605, and the second lighting installation is on the side of the screen opposite the driver's side 600. When the image is generated in limited vision mode, it is mainly visible within a vision range A+ and according to the passenger's viewing angle 610; This passenger viewing angle 610 is, for example, practically parallel to the normal to the surface of the screen 100.However, when the image is generated in free vision mode, it is visible in the vision range A+, A and B and . Thus, it is visible from both the passenger's viewing angle 610 and the driver's viewing angle 615. The driver's viewing angle 615 corresponds to the viewing angle of the driver seated on the driver's side 600 of the vehicle 500. The visibility of the displayed image content is modulated according to the three switching states. Correspondingly, the image content can be blocked for the driver while still allowing an image to be displayed for the passenger.

[0065] Figure 7 shows a flowchart of a method 700 for controlling a screen According to one embodiment, the method 700 presented is used to control a screen such as the one described in Figures 1, 3, 5, and 6. The method 700 includes a step 705 for unilaterally controlling the first lighting system to limit the distribution of brightness on the image-generating layer and thus provide a limited first viewing mode. In another embodiment, the unilateral control step, as an alternative to the first lighting system, controls the second lighting system to limit the distribution of brightness on the image-generating layer and provide a second limited viewing mode, different from the first limited viewing mode.

[0066] The method 700 includes a step 710 for simultaneously controlling the first and second lighting installations to extend the brightness distribution over the image-generating layer and provide a free-viewing mode. In another embodiment, the method may perform only the unilateral control step or the simultaneous control step. In other words, with the method 700 of this embodiment, we have a control method adapted to the screen described above. For private mode, only the first LED strip is powered. The brightness curve corresponds primarily to a symmetrical curve like the one described using [Fig. 2]. In public mode, the first and second LED strips are powered in combination by adjusting an appropriate ratio of the powers of the first and second LED strips to fulfill the brightness requirements for the different viewing ranges as closely as possible.Thus, the light emission from the lower light guide and that from the upper light guide are superimposed (superposition principle). In short, an asymmetrical brightness curve is obtained, adapted to the actual brightness requirements, as described in [Fig. 2]. When integrating the screen into a vehicle, in step 710 of the simultaneous control, the half of the image screen facing the vehicle's side window remains cut off.

[0067] Figure 8 shows the flowchart of a method 700 for controlling a screen according to an exemplary embodiment. The method 700 thus presented corresponds to or is analogous to the method described with reference to Figure 7, except that it includes an additional step. In this exemplary embodiment, the method 700 includes a Step 800 involves controlling a third lighting system simultaneously with the first and second lighting systems to extend the brightness distribution across the image-generating layer and enlarge the free-viewing mode. This results in a symmetrical brightness curve, as described in [Fig. 4]. In another embodiment, the third lighting system can be controlled independently or simultaneously with the first and second lighting systems to obtain an asymmetrical brightness curve.

[0068] Figure 9 is a schematic cross-sectional view of another screen 900. The screen 900 is analogous to the screen described using Figures 1, 3, 5, and 6 for the construction of the different layers. Thus, the image screen 900 in this example embodiment has a surface reflector 905, a lower surface light guide 910, and an upper surface light guide 915 with light-diffusing structures provided, for example, on the lower side, a lower LED strip 920, shown only as an example, as being parallel to one of the two long sides of the lower light guide 910, and an upper LED strip 925 parallel to one of the two long sides of the upper light guide 915. The two LED strips 920 and 925 in this example embodiment are both on the same side of the screen 900. In another example embodiment, the LED strips can be placed either on the same long side or on opposite sides.In this embodiment example, the screen also includes a stack of optical films between the two light guides 910, 915 to group the diffuse light rays coming out of the lower light guide 910.

[0069] This stack or assembly comprises, by way of example, only a diffuser film 930, a first prismatic film 935, a second prismatic film 940, and a lamellar film 945. Above the upper light guide 915, there is an image layer 950 to generate an image. Controlling the two light guides 910, 915 of the screen in this example embodiment allows only two distinct viewing modes (public mode and private mode). Installing the LED strips 920, 925 as described presents other disadvantages compared to the screen described with reference to Figures 1, 3, 5, and 6. Thus, to meet the brightness requirement of the public mode according to the passenger's angle, a very high power consumption is required. This results in a relatively smooth curve and, in particular, one that is almost always symmetrical in public mode, as shown in [Fig.

[10] ; this translates into the realization of the optical design of the second light guide in conjunction with the illumination of the second light guide on the selected large side. Correspondingly, on the one hand, the target brightness is significantly exceeded according to the viewing angles in the viewing ranges A and B and, furthermore, in public mode, due to the practically symmetrical curve, there will always be significant brightness in the direction of the side window, even though this is undesirable in adjustment mode.

[0070] This design is also the reason why this driver mode or economy mode arrangement cannot be guaranteed. In other words, there is excess, unnecessary brightness. Thus, to achieve the target brightness within the relevant ranges, power levels greater than 40 W are required (power based on a 12.3-inch diagonal display in 8:3 format). Such high power is generally unacceptable for vehicle applications. Therefore, to avoid damaging the display system through overheating, even at low ambient temperatures, the lighting power must be reduced, which results in the brightness requirement for the passenger viewing angle not being met. Since the two LED strips 920 and 925 are on the same long side in the (x) direction—that is, they are superimposed—the heat is concentrated in this area.This can result in additional hot spots if both LED strips are powered simultaneously in public mode. Consequently, the electrical power of the backlighting or the brightness must be reduced to prevent unacceptable overheating and damage to the module. As a result, the required brightness levels will not be met. Furthermore, due to the essentially symmetrical curve for the passenger viewing angle, even in public mode at wide lateral viewing angles (greater than 40°) with high brightness levels, depending on the vehicle's geometry and the integration location of the CDD co-pilot display in the dashboard, there is a risk of reflections of the displayed image onto the vehicle's side windows. This is undesirable, especially in dark environments (such as during nighttime driving).

[0071] Figure 10 shows a graph of a brightness curve for an example embodiment of a screen like the one described above with reference to Figure 9. Alongside the brightness curve of the screen described with reference to Figures 1, 3, 5, and 6, with a brightness curve of 1005 for the limited viewing mode, the practically flat brightness curve of the screen in Figure 9 in the free viewing mode is shown. In particular, the curve is still essentially symmetrical, as indicated, and therefore the right half of the screen towards the side glass cannot be darkened. It follows that this device can only operate in two viewing modes.

[0072] NOMENCLATURE OF MAIN ELEMENTS

[0073] 100 Screen

[0074] 105 Image generating layer

[0075] 110 Reflective layer

[0076] 115 First light guide

[0077] 120 First lighting installation

[0078] 125 Light source

[0079] 130 First direction of illumination / direction of radiation

[0080] 135 Diffusion layer

[0081] 140 First prismatic layer

[0082] 145 Second prismatic layer

[0083] 150 Lamellar layer

[0084] 155 Second light guide

[0085] 160 Second lighting installation

[0086] 165 Light source

[0087] 170 Second direction of radiation

[0088] 200 Graph

[0089] 205 Symmetrical brightness curve

[0090] 210 Asymmetric brightness curve

[0091] 300 Third lighting installation

[0092] 305 Light source

[0093] 400 Graph

[0094] 410 Brightness curve

[0095] 415 Symmetrical brightness curve

[0096] 500 Vehicle

[0097] 600 Driver's side

[0098] 605 Passenger side

[0099] 610 Passenger's viewing angle

[0100] 615 Driver's viewing angle

[0101] 700 Method for controlling a screen

[0102] 705 Step in the process

[0103] 710 Step in the process

[0104] 900 Screen

[0105] 905 Reflector

[0106] 910 Light guide

[0107] 915 Light guide

[0108] 920 LED cord

[0109] 925 LED cord

[0110] 930 Film diffuser [YES] 935 First prismatic film

[0112] 940 Second prismatic film

[0113] 945 Lamellar film

[0114] 950 Image layer

Claims

Demands

1. Screen (100), comprising: - a first image-generating layer (105) for generating an image to be emitted, - a first surface-shaped light guide (115) for illuminating the image-generating layer (105), - a second surface-shaped light guide (155) for illuminating the image-generating layer (105), the first light guide (115) and the second light guide (155) being parallel to each other and / or being stacked, - at least one first lighting installation (120) coupled to the first light guide (115) and comprising an array of light sources (125) juxtaposed in rows for emitting light in a first lighting direction (130), the first lighting installation (120) being practically parallel to one side of the first light guide (115),- at least one second lighting installation (160) coupled to the second light guide (155) and comprising a set of light sources (165) juxtaposed in rows to emit light in a second lighting direction (170) screen characterized in that the first lighting installation is on a long side and the second lighting installation is on the short side of the screen so that the lighting sources are distinguished from each other by their lighting directions, the two lighting installations (120, 160) being controlled both independently of each other and also simultaneously or in combination.

2. Screen (100) according to claim 1, comprising: a third lighting installation (300) coupled to the second light guide (155) and comprising an array of light sources (305) juxtaposed in rows to emit light in a third lighting direction (310) opposite to the second lighting direction (165), and the third lighting installation (300) being installed on the side of the second light guide (155), opposite to the second lighting installation (160).

3. Screen (100) according to any one of the preceding claims, wherein the first lighting installation (120) is made to emit in the first lighting direction (130) at an angle less than 150° to the second lighting direction (170), in particular at an angle that is practically 90° to the second lighting direction (170), or the first lighting installation (120) is made to emit in the first lighting direction (130) at an angle greater than 150° and at an angle less than 210° to the second lighting direction (170), in particular at an angle practically 180° to the second lighting direction (170).

4. Screen (100) according to any one of the preceding claims, comprising: a reflective layer (110) for reflecting light rays, the reflective layer (110) being provided on the side of the first light guide (115) opposite the second light guide (155).

5. Screen (100) according to any one of the preceding claims, comprising: a diffusion layer (135) for distributing light rays homogeneously, the diffusion layer (130) being provided between the first light guide (115) and the second light guide (155) and in particular the diffusion layer (130) is made as back side applied as bonding coating by the material of a first prismatic layer (140).

6. Screen (100) according to any one of the preceding claims, comprising: a first prism layer (140) and a second prism layer (145) for directing light rays, the first prism layer (140) and the second prism layer (145) being located between the first light guide (115) and the second light guide (155).

7. Screen (100) according to any one of the preceding claims, comprising: at least one lamellar layer (150) for concentrating light rays and / or for absorbing diffuse light rays, the lamellar layer (150) being provided between the first light guide (115) and the second light guide (155).

8. Vehicle (500) comprising a screen (100) according to any one of the preceding claims, - the screen (100) being installed on the passenger side (605) of the vehicle (500), and - the second lighting installation (160) being on the side of the screen (100) not turned towards the driver's side (600).

9. A method (700) for controlling a screen (100) according to any one of claims 1 to 7, the method (700) comprising the following steps (705, 710) of: - uniquely controlling (705) the first lighting installation (120) to limit the distribution of brightness on the image-generating layer (105) and a first limited viewing mode, or uniquely controlling (705) the second lighting installation (160) to limit the distribution of brightness to the image-generating layer (105) and a second limited viewing mode that differs from the first limited viewing mode, and / or - simultaneously controlling (710) the first lighting installation (120) and the second lighting installation (160) to extend the distribution of brightness on the image-generating layer (105) and generate a free viewing mode.

10. Method (700) according to claim 9, comprising: a step (800) of controlling a third lighting installation (300) at the same time as the first lighting installation (120) and / or the second lighting installation (160) to further extend the distribution of brightness on the image-generating layer (105) and enlarge the free visibility mode.

11. Control device (320) designed to carry out steps (705, 710) of process (700) according to any one of claims 9 or 10 with corresponding units.

12. Screen (100) according to any one of claims 1 to 7, comprising a control device (320) according to claim 11.

13. Computer program designed to perform steps (705, 710) of the process (700) according to any one of claims 9 or 10, when the program is executed by computer.

14. Machine-readable memory support comprising the recording of the computer program according to claim 13.

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