WO2013012360A1

WO2013012360A1 - Transparent element for providing a view point dependent information device and viewpoint dependent information device

Info

Publication number: WO2013012360A1
Application number: PCT/SE2011/000135
Authority: WO
Inventors: Victor TRENT; Pontus Larsson
Original assignee: Volvo Technology Corporation
Priority date: 2011-07-18
Filing date: 2011-07-18
Publication date: 2013-01-24

Abstract

The present invention discloses (i) a transparent element (44, 54) arranged or arrangeable at a mobile and/or immobile host object (42) for providing a viewpoint dependent information device (40) comprising information (34) for a target object (30), wherein the information (34) is perceptible for the target object (30) in dependence on the target object's (30) relative position to the host object (42), characterized in that the transparent element (44, 54) comprises at least one optical structure (46, 58) that controls the perceptibility of the information (34), (ii) a viewpoint dependent information device (40) comprising such a transparent element (44, 54) and (iii) a host object (42) comprising such a transparent element (44, 54) and/or such a viewpoint dependent information device (40).

Description

Transparent element for providing a view point dependent information device and viewpoint dependent information device

Description:

[0001] The present invention relates to a transparent element arranged or arrangeable at a mobile and/or immobile host object for providing a viewpoint dependent information device comprising information for a target object, wherein the information is perceptible for the target object in dependence on the target object's relative position to the host object. The present invention further relates to a viewpoint dependent information device comprising such a transparent element and to a host object comprising the same.

[0002] In the following the phrases "target object" or "target" are used for indicating a recipient of the information provided by the viewpoint dependent information device and the phrases "host object" or "host" or "host vehicle" are used for indicating an element which the transparent element or the viewpoint dependent information device is arranged at or attached to or arrangeable at or attachable to.

[0003] Persons or more generally target objects are usually provided with a plurality of information. Due to the plurality information it is necessary for a target object to filter relevant information from irrelevant information. Thereby relevant information is often location dependent. Such a location dependent or more generally viewpoint dependent relevant information may be for example a traffic sign, e.g. a speed limit, for an exit lane on a high way. This speed limit is irrelevant for the drivers remaining on the high way, but highly relevant for the drivers exiting the highway at this exit. Another viewpoint dependent relevant information may be for example if a person enters or approaches a dangerous location, e.g. a crossing or a blind spot of a vehicle, or enters an advertising area. [0004] Since there usually is an overflow of relevant and irrelevant information, there is always the risk that a target object disregards relevant information, which may cause hazardous situations. For example, accidents often happen in situations where a person (target object) is not aware of being in or close to a dangerous location as the target object has disregarded the corresponding information. E.g. in factories many accidents occur due to moving machineries and workers not being aware of them. Considering traffic accidents, many accidents are related to target objects being in the blind spot area around a vehicle (host vehicle), where the target object is not aware of the blind spot situation and/or has disregarded a corresponding warning.

[0005] It should be noted that the present invention deals with all kind of information and is not restricted to the situations where a target object is in a dangerous location or in a blind spot of a vehicle as mentioned above. A target object entering or approaching the blind spot of a vehicle (host object) is only a simple but descriptive example for the advantages of viewpoint dependent information, since the information of being in a blind spot is only relevant for a target object which is in fact in a blind spot.

[0006] In general, it is object of the present invention, to provide information to a target object in such a way that the risk of disregarding relevant information is reduced. It is another object of the present invention to provide a viewpoint dependent information device which is both precise and easy to arrange at, attach to, or integrate into a host object.

[0007] This objects are solved by a transparent element according to claim 1 , a viewpoint dependent information device according to claim 16, and a host object according to claim 32.

[0008] The invention is based on the idea to provide a transparent element which may cover at least partly an information sign which is provided on a host object, wherein the transparent element comprises at least one optical structure which is adapted to control the visibility of the information in dependence on a relative position of a target object to the information. Thereby a viewpoint dependent information device may be provided which is only perceptible for the target object in a certain relative position to the host object, particularly only if the target is within or close to an information area in which information provided by the viewpoint dependent information device is relevant for the target object.

[0009] In the following the phrase "viewpoint dependent information device" may regard the combination of transparent element and information, but it may also be used in situations, where the inventive transparent element is only placed on an already existing information device, whereby a viewpoint dependent information device is formed. Further, it should be understood that the host object may be an object onto which the information is attached or attachable, or which already comprises the information, e.g. is an information sign such as a traffic sign.

[0010] Preferably, the information may be an, even already existing, image, a warning sign, symbol, text, decal, or other device, arranged or arrangeable at the host object, which may be equipped with the inventive transparent element so that the information is only perceivable for a target when the target is within or close to the information area. The information would thus cease when the target is no longer within or close to the information area.

[0011] The primary difference of the invention compared to existing, static warning signs is that the invention provides information to the target object only, or warns the target object only, when the target object is in or very close to the information area. The advantage of this is twofold. First, the fact that something is changing at the host object draws the attention of the target object to the viewpoint dependent information device and thereby to the information. Therefore, there is a greater chance that the target object actually will notice the information as opposed to a situation where the information is continuously visible. Second, by adding the viewpoint dependence, the target object is provided only with information relevant for the location and may get a more intuitive understanding of where the information area of the host object starts and ends, which is particularly advantageously, if the information is a warning relating to a dangerous location.

[0012] For example, in case the host object is a truck and the driver of a passenger car is the target object, the viewpoint dependent information device is adapted not to be perceptible by the driver in the passenger car when the truck driver can see the passenger car in the truck's side mirrors. As the passenger car enters or approaches the truck's side blind spot area, the warning becomes perceivable for the driver of the passenger car who then becomes aware of the potentially hazardous situation and can take evasive action (e.g. pass the truck quickly or slow down or change the lane to a lane that is more remote from the truck than the current lane - until the warning is no longer is perceptible for him).

[0013] Although the above example deals with a situation where a truck and a passenger car are involved, the invention would be applicable to other situations. For example, the viewpoint dependent information device may warn workers in a factory or on a construction site of moving machineries e.g. of crossing construction machines at intersections or moving robots, or for alerting an operator at an assembly line not to move in the wrong direction.

[0014] Another dangerous situation may arise at an airport. There, the inventive viewpoint dependent information device may alert persons of moving aircrafts, moving machineries or if e.g. a person stands too close to an engine of an aircraft.

[0015] Besides the use as warning, the inventive viewpoint dependent information device may also be used as traffic sign, e.g. at intersections so that a driver can only see the traffic signs in his/her direction, and/or for two parallel roads, where it might be confusing if a drivers sees the signs on the parallel road, for example speed signs, and/or at intersections so that a driver does not see the traffic light that is for other lanes than his own lane. Another application may be for example at an airport for directing passengers to the gates. A further possible application is a sea mark, e.g. a buoyage and/or lighting sign. For example the viewpoint dependent information device may be adapted to inform a skipper of a prohibition to anchor because of an electrical cable on the seabed. Another application is as "light house" during daylight, where dependent on the position of a vessel in a waterway, the viewpoint dependent information device shows a red or a green sign when the vessel is not positioned correctly in the waterway and a white sign when the vessel is positioned correctly. The viewpoint dependent information device then works similar to a lighthouse by daylight. Thereby, the same navigational aid is provided as by lighthouses, but during daytime and at very low cost.

[0016] Besides the above discussed applications it is also possible to use the viewpoint dependent information device for advertising purposes.

[0017] According to a preferred embodiment of the present invention, the viewpoint dependent information device may be adapted to inform a target object not only when the target object enters the information area, but also when the target object is approaching the information area. In case the information provided by the viewpoint dependent information device relates to dangerous situations, the target object may take countermeasures for avoiding the dangerous area at an early stage, preferably even before the target object has entered the dangerous area. Thereby, a hazardous situation for the target object due to the stay in a dangerous area (e.g. a blind spot area of another vehicle like a truck) may be avoided. The pre-warning may be realised by e.g. a change in colour, change in brightness, change of message etc. of the information perceived by the target object.

[00 8] Advantageously, the change may be realized by a viewpoint dependent information device which is adapted to show at least two different images, wherein it depends on the viewpoint of the target object which image is visible for the target object.

[0019] Further, the inventive viewpoint dependent information device provides a possibility to direct the target object's attention to the information, e.g. the warning, provided on them. This is due to a change in the appearance of the device when the target object approaches, enters or leaves the information area of the host object. If, additionally, the information or the warning is self-explaining, e.g. by showing the text "Blind Spot" or "Danger" when the target object is in the information area, the boundaries of the information area are intuitively communicated to the target object.

[0020] According to a preferred embodiment of the present invention, the viewpoint dependent perceptibility of the transparent element may be achieved by prismatic technology. Preferably, the transparent element has at least one prism-shaped structure, preferably a plurality of parallel oriented elongated prisms. The prism-shaped optical structure enables that only within a certain area, the boundaries of which are defined by a so-called "flip" angle, light passes through the optical structure and is reflected off the underlying surface (containing the information) and back to an observer. This means, if the target object is within or close to the information area, i.e. within the boundaries defined by the "flip" angle, the target object may see the information. If the target object is not within or close to the information area, i.e. is outside the boundaries defined by the "flip" angle, the light does not pass through the optical structure of the optical structure but is reflected back to the target object, thereby presenting a reflective surface. As a consequence the underlying information is invisible for the target object. Thereby, the awareness of the target object concerning the information provided by the viewpoint dependent information device may even be enhanced by the reflective surface of the viewpoint dependent information device, even if the underlying information itself is not (yet) perceptible as long the target object is not (yet) within the boundaries defined by the "flip" angle.

[0021] The boundaries of the information area may be defined by the geometry of the prismatic structure and/or the refractive index of the material of the prismatic structure. Advantageously, the at least one prism has an apex angle, which is adapted to the boundaries of the information area, so that the warning is only perceptible for a target object if the target object is within or close to the information area of the host object.

[0022] According to a further preferred embodiment, the viewpoint dependent perceptibility of the information may be based on lenticular technology, wherein preferably the transparent element comprises at least one, preferably semicircular, lens, wherein the lens is adapted to direct light to the information dependent on the target's relative position to the host object.

[0023] According to a further preferred embodiment, the viewpoint dependent perceptibility of the information may be based on holographic technology, wherein preferably the relative position of the target determines light amplitude and light phase reflected by the transparent element so that the information is shown or not.

[0024] According to a further preferred embodiment, the viewpoint dependent perceptibility of the information may be enhanced by at least one light obstructing element obstructing the view onto the information if the target object is outside the information area of the host object. This light obstructing element may be an opaque layer, which is preferably arranged at at least one of the sides of the optical structure providing the viewpoint dependent perceptibility, e.g. at the prismatic structure, lenticular structure or holographic structure.

[0025] Advantageously, the opaque layer may also be used for providing the above described pre-information. According to a preferred embodiment of the invention, a message or image may be printed onto the opaque layer informing the target object at an early stage of the approach to the information area.

[0026] According to a further preferred embodiment, the light obstructing element may be a microlouver layer, wherein the microlouver layer comprises miniature opaque louvers, preferably integrated in a transparent film. The miniature opaque louvers obstruct the light reflected off the viewpoint dependent information device from reaching other angels than those which refer to the information area.

[0027] Alternatively or additionally, the light obstructing element is at least one blind, preferably arranged at the circumference of the device, obstructing the view onto the image if the target object is outside the blind spot area of the host vehicle.

[0028] According to a further preferred embodiment, the light obstructing element is mechanically and/or electrically adjustable for calibrating the viewpoint dependent information device to the boundaries of the information area, wherein preferably the blinds are adjustable.

[0029] Thereby, different information area angles may be applied, so that an accurate determination of the information area is possible. Different information area angles and thereby also a different information areas may arise e.g. at different lane widths.

[0030] Advantageously, the viewpoint dependent information device is calibrated to the boundaries of the information area of the host object so that the information is only perceptible if the target object is within or close to the information areas of the host object. Preferably this is realized by exchanging the optical structure, e.g. the prismatic structures.

[0031] According to a preferred embodiment of the invention, the viewpoint dependent information device is arranged or arrangeable at the host object. The viewpoint dependent information device may be an individual device which is attachable to the host vehicle, or the viewpoint dependent information device may already be integrated into the host vehicle e.g. during

manufacturing, particularly during a painting or assembling process.

[0032] Preferably, the viewpoint dependent information device is a passive decal, which is, preferably adhesively or magnetically, attachable to the host object. [0033] Besides a mobile host object as the above described vehicles or moving machineries, it is also possible to attach the viewpoint dependent information device to an immobile host object, such as a building or building part, a part of a landscape, e.g. a rock or a tree, or a traffic sign post.

[0034] Advantageously, the viewpoint dependent information device may comprise a fluorescent material and/or a reflective material and/or a phosphorescent material and/or a chemoluminescent material. By using these kinds of materials, a perceptibility of the viewpoint dependent information device is also given during night time. Additionally, during day time, the perceptibility is enhanced.

[0035] According to a further preferred embodiment of the invention, the viewpoint dependent information device is illuminatable, preferably from its backside. This also enhances the perceptibility of the viewpoint dependent information device. Advantageously, for illuminating the viewpoint dependent information device, on or more lamps and/or one or more LEDs, preferably LED backlight, and/or one or more electroluminescent elements, such as an electroluminated sheet, electroluminated panel and/or electroluminated wire are used. These illumination devices provide an energy saving illumination and are relatively flat so that the viewpoint dependent information device does not become bulky.

[0036] According to a further preferred embodiment of the invention, the viewpoint dependent information device is a computer display. For providing the viewpoint dependent perceptibility, the computer display may be equipped with an optical filter arrangement which, in particular for computer screen applications, is often called "privacy filter", which may be realized by the microlouvers or the prismatic structures, placed on the surface of the display.

[0037] For saving energy, it is advantageous if the viewpoint dependent information device is further adapted to be controlled such that the illumination of the viewpoint dependent information device or an activation of the computer display is performed only upon detection of a target object entering or approaching the information area of the host object. Further, it is also possible to control the illumination of the viewpoint dependent information device so that the illumination flashes in order to further increase the attention of the target object to the viewpoint dependent information device.

[0038] Further it should be noted that a host object can be equipped with more than one type of viewpoint dependent information devices.

Advantageously, a target object's attention can be stimulated and guided by different information when approaching, or being within, the information area whereby it is ensured that the target object is in fact made aware of the information area.

[0039] Consequently, the viewpoint dependent information device may further comprise an acoustic device which is adapted to direct an auditory alert which is only audible for a target object, if the target object is within or close to the information area of the host object. This sound directing is possible by applying a technology using specially arranged loudspeakers, preferably by an ultrasonic parametric array. An ultrasonic parametric array, such as known as "Audio Spotlight", is a technique where an array of ultrasonic transducers is used to produce audible sound with very high directivity. In this technique, the transducers project a narrow beam of modulated ultrasound that is powerful enough (100 to 1 10 dB) to substantially change the speed of sound in the air that it passes through. The air within the beam then behaves nonlinearly and extracts the modulation signal from the ultrasound, resulting in sound that can be heard only along the path of the beam. The basics of this technology are described at

http://www.holosonics.com/tech_directivity.html.

[0040] Another possibility for providing an acoustic viewpoint dependent information is for example to use directional loudspeakers the directionality of which is based on the electrostatic principle. This technology is also known as "sound shower". High directivity is in this case achieved by having a transducer (a loudspeaker) which has an area which is large in comparison to the wavelength of the sound it emits. The electrostatic principle is especially suitable for constructing loudspeakers which both are flat and have a large area. Further information is given by Panphonics Directional Speakers Sound Shower, available at http://www.panphonics.com/directional-speakers.html.

[0041] A further preferred embodiment uses a loudspeaker phased array using traditional loudspeakers which are controlled by a digital signal processing technology and provide an adjustable beam of sound. The focused speaker arrays consist of multiple small, high quality loudspeakers contained in a very thin, unobtrusive unit providing good sound quality and directional audio control. In this technique, a special device (usually a Digital Signal Processor - DSP) controls the phase (or time delay) and relative amplitude of the signal sent to each loudspeaker, in order to create a pattern of

constructive and destructive interference in the wave front which results in a narrow main lobe. More information is available at http://dakotaspeaker.com.

[0042] According to another preferred embodiment a so called "Sound Dome" may be used. This is a parabolic loudspeaker providing a directed sound. Using this technique, one or more loudspeaker drivers are mounted at the focal point of a parabola pointing away from the receiver, toward the parabolic surface. The sound is bounced off the parabolic dish and leaves the dish focused in plane waves. Further information is available at

http://www.browninnovations.com/sound_domes.html.

[0043] As mentioned above, also the acoustic device may further be adapted to be controlled such that an activation of the acoustic information is performed only upon detection of a target object entering or approaching the information area. For providing such a control a controller and detector as explained below with reference to the target object detecting system (TODS) may be used.

[0044] According to a further preferred embodiment, the viewpoint dependent information device is individually manufactured for each host object or for each host object type having substantially similar information areas. For example, the allowed blind spot areas for a vehicle are clearly defined - in Europe for instance by EU-Directive 2003/97/EC of the European Parliament and of the EU-Council - so that the viewpoint dependent information device may be calibrated to the allowable boundaries without measuring the blind spot areas of the host vehicle directly. This provides the possibility to manufacture the appropriate viewpoint dependent information device (for instance in form of a decal) that is adapted to each and every type of host vehicle and to give detailed information where the decal is to be mounted at the corresponding host vehicle. This in turn creates a retrofitting possibility, which is available and useable for all vehicles concerned without the need to visit a repair shop in order to be retrofitted with such viewpoint dependent information devices. Thus, it is for example possible to sell viewpoint dependent information devices (a decal for instance) at a gas station which the driver easily can mount to the vehicle all by himself. This fact may increase the acceptance and the spread of such devices, which in turn may increase the safety on the streets.

[0045] According to a further preferred embodiment of the invention, the calibration to the boundaries of the information area of the host object is performed once during fitting up of the host object.

[0046] According to a further preferred embodiment of the invention, the calibration is performed, manually or automatically, if a change in the boundaries of the information areas to be expected, e.g. dependent on a change in a lane width a vehicle is travelling on. Thereby, the viewpoint dependent information devices can be individually and continuously be adapted to different driving situations. For that it may be possible that the transparent sheet with the optical structure e.g. the prismatic structure is exchangeable.

[0047] According to a further preferred embodiment of the invention, the vehicle is a vehicle-trailer-combination, particularly a truck trailer combination, and the calibration is performed, manually or automatically, if the vehicle- trailer-combination changes. [0048] According to a further embodiment of the invention, the viewpoint dependent information device may further comprise at least one detector for detecting a target object within or close to the host object's information area. Additionally, the viewpoint dependent information device may further comprise a controller which is adapted to control the viewpoint dependent information device to be perceptible when a target object is detected to be within or close to the information area.

[0049] According to a further preferred embodiment of the invention, the at least one detector comprises at least one sensor, particularly a camera, and/or a radar sensor, for detecting a target object.

[0050] A system comprising a detector for detecting a target object entering the information area and the controller for issuing an information upon detection of a target object entering the information area is named a target object detection system (TODS) in the following.

[0051] According to a further preferred embodiment of the invention, the viewpoint dependent information device may further be arranged at a mechanical device, which is controlled e.g. by the target object detecting system to be on display upon detection of a target object within or close to the information area. This mechanical device may be a mechanical arm, which extends or pops out upon detection of a target object within the information area.

[0052] According to a further embodiment of the invention, the target object may further comprise an internal interface which is adapted to receive an information signal from an outside source, particularly from the host object, wherein the viewpoint dependent information device of the host object is adapted to transmit the information signal to the target object's internal interface upon detection of the target object being within information area of the host object. This has the advantage, that e.g. a driver can be directly informed by means of e.g. a driver assistance system, which also reduces the possibility to disregard the viewpoint dependent information. [0053] According to a further preferred embodiment of the invention, the target object's internal interface is at least one of an information display, a telltale light, a sound system and a driver assistance system, whereby preferably at least one of an audio, visual and tactile warning can be issued.

[0054] According to a further preferred embodiment of the invention, the viewpoint dependent information device is adapted to transmit an information signal to the target object's interface by means of at least one of a wireless computer network, particularly for traffic safety, Global Positioning System (GPS)/Differential GPS (DGPS), Radio Data System (RDS) or similar.

[0055] Further advantages and preferred embodiments are defined in the claims, the Figures and the description.

[0056] In the following, the invention will be discussed with help of the attached Figures. The description thereof is considered as exemplification of the principles of the invention and is not intended to limit the scope of the claims.

[0057] The Figures show:

Fig. 1 : a schematic illustration of typical blind spot areas of a truck-trailer-combination;

Fig. 2: a schematic illustration of the functioning of a preferred embodiment of the invention;

Fig. 3: a schematic illustration of a further preferred embodiment of the invention indicating a blind spot warning zone;

Fig. 4: a schematic illustration of the preferred embodiment

shown in Fig. 3 indicating a blind spot warning zone and a blind spot pre-warning zone;

Fig. 5: a schematic cross sectional view of a first preferred

embodiment of the inventive viewpoint dependent information device; Fig. 6: a schematic illustration of the functioning principle of the preferred embodiment depicted in Fig. 5;

Fig. 7: a schematic cross sectional view of a second preferred embodiment of the inventive viewpoint dependent information device;

Fig. 8: a schematic cross sectional view of a third preferred

embodiment of the inventive viewpoint dependent information device; and

Fig. 9: a schematic cross sectional view of a fourth preferred embodiment of the inventive viewpoint dependent information device.

[0058] In the following same or similar parts in the Figures are indicated by the same reference numerals

[0059] In the description of Figs. 1 to 4, the principle of the invention will be explained in relation to the exemplary application of the viewpoint dependent information device as blind spot warning device for warning a road user (target object) of a blind spot area of a vehicle, particularly of a truck. Consequently, the host object or host vehicle is the vehicle and the target object is the other road user, particularly the driver of another car. The information indicated by the inventive viewpoint dependent information device is in the illustrated examples a blind spot warning which is adapted to warn other road users if they are in the potentially dangerous situation of the blind spot area of the host object.

[0060] Fig. 1 shows a schematic top view of a truck-trailer combination 10 comprising the cabin 12 of the truck (the other details of the truck or omitted for clarity reasons) and a trailer 14. Usually, the driver of the truck 10 can directly observe his environment through the windscreen and the side windows of the truck's cabin 12. Thereby, areas 16, 18 and 20 outside the cabin 12 are directly visible for the driver of the truck 10. Indirectly through mirrors (not shown), the areas indicated by reference signs 22 and 24 are also visible for the driver of the truck. However, there remain a number of blind spot areas 1 to 8, which are not, neither directly nor indirectly, observable for the driver of the truck 10.

[0061] While additional mirrors can increase the driver's area of view, this solution can have negative aerodynamic effects and also increase the complexity of the driver interface. Moreover, mirrors are difficult to adjust and wide angle mirrors provide only distorted views of the surrounding traffic.

[0062] Active systems which detect and warn the driver of objects present in the blind spot areas may be another solution to the problem. However, this still does not solve the key problem in many blind spot accidents namely that the road user in the blind spot area of another vehicle is not aware of that he cannot be seen by the driver of said other vehicle. If the road user knows that he is within the blind spot area of said other vehicle it is easy for him to avoid the blind spot area of said other vehicle for instance simply by passing the other vehicle or letting the other vehicle pass. What is more difficult for the road user is realizing that he is in a blind spot area of the other vehicle.

[0063] As explained above, the current invention may be used for resolving the blind spot problem by warning road users (target objects) surrounding the host vehicle as they enter or approach a blind spot area of the host vehicle by means of a viewpoint dependent blind spot warning device (sign or similar) attached to the host vehicle's exterior, which is only perceptible for the target object dependent on the position of the target object relative to the host vehicle.

[0064] Preferably, the inventive viewpoint dependent blind spot warning device comprises a warning sign, symbol, text, or other device, arranged at, attached to or integrated into, the host vehicle's exterior which is perceivable for a target object only when the target object is within or close to the blind spot area(s) of the host vehicle. The warning would thus disappear for the target object once the target object is no longer within the host vehicle's blind spot area.

[0065] A visualization of how this works is shown in Figures 2, 3 and 4.

[0066] In Fig. 2, a truck 10 is the host object and a driver of a passenger car 30 is the target object. The truck 10 is equipped with a viewpoint dependent blind spot warning device comprising a warning 34 (depicted only in the right panel of Figure 2), which is only perceptible for a road user within or close to the blind spot area. As long as the truck driver can see the passenger car 30 in the truck's side mirrors 32, the warning 34 cannot be seen by the driver in the passenger car 30. This situation is illustrated in the left panel of Figure 2. As the passenger car 30 enters the truck's side blind spot area 1 ; 2, the warning 34 becomes perceivable by the driver of the passenger car 30 as can be seen on the right panel in Fig. 2. The driver of the passenger car 30 then becomes aware of the potentially hazardous situation and can take evasive action (for instance by passing the truck 10 quickly or by slowing down until the warning 34 is no longer visible for him).

[0067] Fig. 3 depicts the same situation as in Fig. 2, only viewed from above with the truck's cabin 12 and a viewpoint dependent information device 40 attached to e.g. a door of the cabin 12. At a first stage I (corresponding to the situation illustrated in the left panel of Fig. 2), the warning 34 is not perceptible for the target object, i.e. the passenger car 30, and may appear e.g. as a black sign, a reflective surface, or a sign in the colour of the outer surface of the cabin 12 of the truck 10.

[0068] As the driver of the passenger car 30 approaches the blind spot area of the truck 10 and subsequently crosses the boundary of said blind spot area defined by angle a at stage II (corresponding to the situation illustrated in the right panel of Fig. 2), the warning 34 of the viewpoint dependent information device 40 becomes perceptible for the driver of the passenger car 30, depicting e.g. the message "Blind Spot" or "You are in the blind spot" or appear as a sign turning from e.g. black colour or from the colour of the outer surface of the cabin 12 of the host vehicle 10 into e.g. a bright red or bright orange sign.

[0069] Instead of warning the driver of the passenger car 30 only if he is crossing the boundary of the blind spot area and entering the blind spot area of the host vehicle, i.e. the truck 10, it is also possible to pre-warn the driver of the passenger car 30 by informing him that he is approaching a blind spot area of another vehicle near to him. Such an embodiment of the present invention is schematically illustrated in Fig. 4.

[0070] In this depicted embodiment of the invention, the warning sign 34 of the viewpoint dependent information device 40 is not perceptible to the driver of the passenger car 30 in stage I, as already described in relation to Figures 2 and 3. As the driver of the passenger car 30 approaches the blind spot area of the truck 10 he is informed by the warning 34 of the viewpoint dependent information device 40 at the host vehicle 10 of this approach by a pre-warning (see stage II). If the driver of the passenger car 30 continues approaching the blind spot area of the host vehicle 10 and finally enters the blind spot area itself, the warning sign 34 of the viewpoint dependent information device 40 changes again and shows the blind spot warning (see stage III).

[0071] This change of information may also be performed by e.g. changing colour (e.g. from black to yellow (or orange) to red), by changing message (no message, pre-warning message, warning message), changing brightness (dark, semi-dark, bright), or in case of an additional acoustic device by changing loudness (silent, normal, loud). Preferably, the boundaries of the three stages l-lll are sharply defined so that a sudden change of the warning draws the attention of the driver of the target vehicle 30 to the viewpoint dependent information device of the host vehicle 10. However, it is also possible to gradually change the appearance of the viewpoint dependent information device.

[0072] Fig. 5 depicts a sectional view through a first preferred embodiment of an inventive viewpoint dependent information device 40. In this embodiment, the viewpoint dependent information device 40 comprises a decal 41 with an information (34 in Figs. 3 and 4) printed on, which is preferably adhesively or magnetically attachable or laminatable or moldable to a host object 42, e.g. to the door of a truck as shown in Fig. 2, to an aircraft, to a traffic sign, to a wall of a building, or even to a tarmac of a road.

[0073] On the top surface of the information decal 41 a first preferred embodiment of the inventive transparent element 44 is arranged. The depicted inventive transparent element 44 is designed as transparent sheet comprising several, parallel arranged elongated prisms 46. The prisms 46 may have a triangular of other suitable "prismatic" shape. The geometry of the prisms 46 is defined by an apex angle Θ, which in turn determines the visibility of the information decal 41 and is adapted to the boundaries of the information area of the host object 42. Besides the apex angle Θ also the refractive index of the material of the transparent sheet 44 may influence the visibility of the information decal 41. It should be noted that even if in the Figs. 5, 6 and 7 symmetric equal-sided prisms are illustrated, also asymmetric odd-sided prisms may be used.

[0074] By changing the geometry, in particular the apex angle Θ, of the prismatic structure 46, and/or by changing the refractive index of the material of the transparent sheet 44, different so-called "flip" angles and thereby different boundaries of the information area may be obtained. Within the boundaries defined by the "flip" angle, light passes through the prism 46 and is reflected off the information decal 41 and back to an observer. This means, if the target object is within or close to the information area, i.e. within the boundaries defined by the "flip" angle, the target object may see the information. If the target object is not within or close to the information area, i.e. is outside the boundaries defined by the "flip" angle, the light does not pass through the optical structure of the optical structure but is reflected back to the target object, thereby presenting a reflective surface. As a consequence the underlying information is invisible for the target object. Thereby, the awareness of the target object concerning the information provided by the viewpoint dependent information device may even be enhanced by the reflective surface of the viewpoint dependent information device, even if the underlying information itself is not (yet) perceptible as long the target object is not (yet) within the boundaries defined by the "flip" angle.

[0075] The transparent sheet 44 may be permanently attached to the information decal 41 e.g. by laminating or gluing e.g. the edges of the transparent sheet 44 to the information decal 41. However, it is also possible that the transparent sheet 44 is removably attached to the information decal 41 . By changing the transparent sheet 44 and thereby the geometry of the prisms 46 and/or the material of the transparent sheet 44, the viewpoint dependent information device 40 is calibratable to different boundaries of the information area concerned.

[0076] Preferably, between the transparent sheet 44 and the information decal 41 remains a gap 47, the function of which will explained in the following with reference to Fig. 6.

[0077] The influences of the apex angle Θ and the refractive index on the visibility of the information decal 41 are depicted more in detail in Fig. 6, showing a schematic view of light beams passing through the transparent sheet 44.

[0078] At very acute angles of incidence, αι , and corresponding acute angles of viewing, a light beam may pass through the prism 46 and is reflected back from the information decal 41 so that the information decal 41 and therefore the information 34 can be seen (see Fig. 6a). As the light beam incident angle and the viewing angle become less acute, the reflected light beams are oriented more and more perpendicular to the surface normal of the information decal 41 . However, at angles above a certain angle of incidence (a₂), the light beam which travels through the prism 46 has such an critical angle relative the surface normal (a_c) that it undergoes total internal reflection (see Fig. 6b) so that the light beam cannot penetrate the prism 46 anymore and, consequently, does not reach the underlying information decal 41 anymore. As a

consequence, the information decal 41 becomes obstructed at viewing angles corresponding to or greater than 02, and the driver of the target vehicle instead sees a reflective surface, only.

[0079] Total internal reflection is an optical phenomenon that occurs at a boundary layer between two transparent medium having different refractive indices, such as air present in gap 47 and the material of the transparent sheet 44. Usually, when light crosses the boundary between the materials with different refractive indices, the light will be partially refracted and partially reflected at the boundary surface. At the certain critical angle a_c, the light is no longer refracted but instead totally reflected, even if the boundary surface is not reflective. However, total internal reflection can only occur where light travels from a medium with a higher refractive index n1 to a medium with a lower refractive index n2. In the present case, this happens when the light beam is passing from the transparent sheet 44 to gap 47 filled with e.g. air, but not when it passes from air to the transparent sheet 44.

[0080] The critical angle a_c can be determined by Snell's law of refraction: a_c = arcsin (n2/n1 ). Provided the transparent sheet 44 is made from transparent plastic, e.g. Polymethacrylmethylimid (PMMI), which has a refractive index of n2= 1.53, total reflection occurs roughly at angles a_c > 40°. Consequently, changing the refractive index of the material of the transparent sheet 44 changes also the critical angle a_c for the total reflection, whereby in turn the viewpoint dependent information device may be calibrated to the boundaries of the information area.

[0081] As mentioned above, total internal reflection only occurs if a light beam passes from the transparent sheet 44 to a material having a lower refractive index, particularly air. Consequently, when attaching the transparent sheet 44 to the information decal 41 it should be ensured that either a small gap 47 filled with air remains between the back of the transparent prism sheet 44 and the information decal 41 or the material directly adjacent to the transparent sheet 44 has a refractive index which is lower than the refractive index of the transparent sheet 44. For example, the information decal 41 and the transparent sheet 44 may be glued together using a glue or adhesive having a refractive index that is lower than the refractive index of the transparent sheet 44.

[0082] At very flat angles of incidence (βι , with β-ι equal to or larger than ₂), the light is guided through the prismatic structure 46 instead of being reflected towards the observer (i.e. the driver of the target vehicle), which also is an effect rendering the warning sign invisible for a driver of a target vehicle that is outside the critical stages l-lll, see Fig. 6c.

[0083] By changing the geometry, in particular the apex angle Θ, of the prismatic structure 46, and/or by changing the refractive index of the material of the transparent sheet 44, different "flip" angles and thereby different boundaries of the blind spot area may be obtained.

[0084] A positive side effect of the prismatic sheet 44 is that it provides a reflective surface (without the information 34) at viewing angles greater than ct2, which is believed to attract the attention of target objects to the viewpoint dependent information device 40 prior to seeing the information 34.

[0085] The embodiment depicted in Fig. 7 is an alternative to the

embodiment depicted in Fig. 5, where a transparent prismatic sheet 44 is placed in front of the information decal 41. In Fig. 7 however, the "flip" effect has been enhanced by putting an opaque layer 48 on every second side 50 of the prism surfaces 46. The opaque layers 48 efficiently block out the light beams at flat angles of incidence β while light beams at very acute angles (a) can pass through the transparent sides 52 of the prisms 46. Thus, when the target object views the warning sign at flat angles of incidence β, he sees only the opaque layer 48 and not the underlying information 34. As the target object moves to steeper (acute) angles of incidence a, i.e. as the target object enters the information area, the information 34 becomes visible through the transparent sides 52 of the prisms 46.

[0086] Additionally, the opaque layer 48 may be used for issuing a pre- warning to the target vehicle, e.g. by a message or image printed on, attached to or arranged at the opaque layer 48.

[0087] Preferably, the thickness of the transparent sheet 44 is only a few millimeters, so that the overall dimension of the viewpoint dependent information device remains quite flat.

[0088] Fig. 8 depicts a sectional view through a third preferred embodiment of an inventive viewpoint dependent information device 40. In this

embodiment, the viewpoint dependent information device 40 comprises on the top surface of the information decal 41 an inventive transparent element which is designed as a microlouver layer 54, which comprises a transparent film 56 and opaque miniature louvers 58 integrated into the transparent film 56. The opaque miniature louvers 58 may be constituted by an opaque layer, preferably having the same colour as the surface of the host object 42 which can be e.g. laminated between transparent plastic strips. The distance between the miniature louvers 58 and the thickness of the film determine the light obstructing angle and thereby the boundaries of the information area.

[0089] For example, for a target object viewing the decal from angles αι and θ2 the information decal 41 is visible. Thereby the angles CM and a₂

correspond to the information area angles, so that the information is only visible if the target object is within or close to the blind spot zone of the vehicle. At angles such as a₃ and a₄, the decal becomes invisible for the target object due to the opaque layers.

[0090] Preferably, the thickness of the film is only a few millimeters, so that the overall dimension of the viewpoint dependent information device remains quite flat. [0091] It should be further noted, that both a microlouver and a prismatic sheet may be placed on top of each other. Thereby an even better restriction to the information area boundaries may be achieved.

[0092] Since the viewpoint dependent information device may be arranged at a host object's exterior it may also be subject to pollution. Consequently, a protective layer may be arranged on top of the optical layers for avoiding pollution and for easy cleaning. Thereby the protective layer may also fill the gaps between the individual prisms 46 of the prismatic structure depicted in Figures 5, 6 and 7. Since the material of the protective layer may also influence the optical properties of the optical structure, the optical properties of the protective layer are preferably adapted to the used optical structure. For example it is advantageous, if the material of the protective layer has a refractive index which is similar or substantially identical to the refractive index of air. Thereby, it is ensured that the protective layer does not influence the functioning of the optical structure. On the other hand the refractive index may be chosen to be different from air, whereby it is possible to enhance the optical properties of the optical structure. For example, in case the information area is very narrow it might be easier to adapt the material of the protective layer so that the optical structure provides the corresponding information area boundaries, than adapting the optical structure itself.

[0093] It goes without saying that the above discussed geometric forms of the prisms or microlouvers are exemplary only, and also other geometric structures may be used.

[0094] For providing a viewpoint dependent information device which has a very low air resistance the viewpoint dependent information device may be molded into the material and/or structure of the host object. Thereby it is also possible to integrate the viewpoint dependent information device to host objects made from carbon fibers or similar.

[0095] The transparent sheet 44 may also be provided by at least part of the glass of a window, e.g. of a side window of a vehicle, whereby the optical structures for providing the viewpoint dependency may be integrally provided by the window glass. Such a glass may also be the glass of a traffic light so that direction signals may be provided by the same traffic light.

[0096] The information decal may be a simple sticker which is placed behind the corresponding part of the window comprising the optical structures. Such a sticker may be made from a one way mirror film (window privacy film), which is transparent when viewed from one side (e.g. from the inside of the cabin 12) and provides a reflective surface when viewed from the other side (e.g. from the outside). Thereby the information provided on the sticker does not obstruct the view e.g. for a driver.

[0097] As mentioned above, blind spot accidents are very common and e.g. truck drivers encounter blind spot situations daily. It is therefore of great interest for e.g. truck manufacturers and haulage companies to endorse a technology which attempts to solve the blind spot problem. The above described embodiments involve rather simple, passive technologies and are therefore inexpensive and easy to develop and to mass produce which would result in a correspondingly low price for such devices for Original Equipment Manufacturers (OEMs) and end customers. Such solutions make it possible to integrate the viewpoint dependent information device in a very simple and easy way both into the production state of a vehicle and as a retro-fit option.

[0098] Even if some of the above described embodiments are more technically complex and require that a TODS is installed in the target vehicle or supplied with the warning device, they provide a novel and efficient solution to the blind spot problem. These embodiments are particularly suitable for new manufactured vehicles.

[0099] Besides the application in a vehicle, the inventive viewpoint dependent information device is also applicable as traffic sign or as sea mark. Fig. 9 depicts an embodiment of the viewpoint dependent information device 40 which is used as sea mark indicating a water way. [00100] The viewpoint dependent information device 40 in Fig. 9 comprises a three sided geometric object 60, wherein each side 60a, 60b, and 60c comprises information decals 62, 64, and 66, respectively. Each information decal 62, 64, 66 is provided in a different colour e.g. red for information decal 62, white for information decal 64 and green for information decal 66. On top of each decal 62, 64, 66, a transparent sheet 44 is arranged which is adapted to the boundaries of the information areas 72, 74, 76 provided by the differently coloured decals 62, 64, 66. Dependent on where a target object is positioned in the sea, he may see a red, white or green sign, so that he can easily determine whether he is positioned correctly in the waterway. Thus, the viewpoint dependent information device is comparable to a lighthouse, wherein the information area 72 corresponds to the red sector of a light house, the information area 74 corresponds to the white sector of a light house and the information area 76 corresponds to the green sector of a light house. Thereby an effective and cheap navigational aid is provided.

[00101] As can be derived from the above given examples, the application possibilities for the inventive viewpoint dependent information device are manifold and it is not possible to give an example for each and every application. However, the different applications are encompassed by the scope of the claims and a person skilled in the art may come up with a plurality of application possibilities without being inventive.

Reference numerals:

1 - 8 blind spot areas (information areas)

10 truck

2 driver cabin

14 trailer

16 - 24 visible areas for a vehicle driver

30 passenger car

32 side mirror

34 information; warning sign

40 viewpoint dependent information device

41 decal

42 host object

44 transparent sheet

46 optical structure - prism-shaped

47 gap

48 opaque layer

50 opaque side of prism

52 transparent side of prism

54 microlouver layer

56 transparent film

58 louvers

Θ apex angle of prism

Oi - α_4> β, β light beam incident angles (and corresponding viewing a_c critical angle for total inner reflection

Claims

Claims:

1. Transparent element (44, 54) arranged or arrangeable at a mobile

and/or immobile host object (42) for providing a viewpoint dependent information device (40) comprising information (34) for a target object (30), wherein the information (34) is perceptible for the target object (30) in dependence on the target object's (30) relative position to the host object (42), characterized in that the transparent element (44, 54) comprises at least one optical structure (46, 58) that controls the perceptibility of the information (34).

2. Transparent element according to claim 1 , wherein the optical structure (46, 58) is calibrated to boundaries of an information area in which the information (34) provided by the viewpoint dependent information device (41) is relevant for the target object (30) so that the information (34) is only perceptible if the target object (30) is within or close to the information area.

3. Transparent element according to any one of the preceding claims, wherein the transparent element (44, 54) is adapted to make information (34) visible for the target object (30) if the target object (30) is within or close to the information area, wherein the information (34) is depicted as at least one image.

4. Transparent element according to any one of the preceding claims, wherein the transparent element (44, 54) is adapted to make information (34) visible for the target object (30) if the target object (30) is within or close to the information area, wherein the information (34) is depicted as at least two images.

5. Transparent element according to any one of the preceding claims, wherein the transparent element (44, 54) is further adapted to inform the target object (30) of the target object's (30) approach to the information area, preferably by issuing a pre-information, which is only perceptible if the target object (30) is close to the information area.

6. Transparent element according to any one of the preceding claims, wherein the transparent element (44, 54) comprises at least one optical structure (46) which controls the visibility of the information based on prismatic technology, wherein preferably the transparent element (44) comprises at least one prism-shaped optical element (46), preferably a plurality of parallel oriented elongated prisms.

7. Transparent element according to claim 6, wherein between the

information sign (34) and the transparent element (44) a material is present which has a lower refractive index than the material of the transparent element (44), wherein preferably said material is air or an adhesive.

8. Transparent element according to claim 6 or 7, wherein the at least one prism-shaped optical element (46) has an apex angle (Θ), which is adapted to the boundaries of the information area.

9. Transparent element according to any one of the preceding claims, wherein the boundaries of the information area are defined by a refractive index of the material of the transparent element (44) and/or the geometry of the at least one prism-shaped optical element (46).

10. Transparent element according to any one of the preceding claims, wherein the visibility of the information (34) is further controlled by at least one light obstructing element obstructing the view onto the information (34) if the target object (30) is outside the boundaries of the information area.

11. Transparent element according to claim 10, wherein the light

obstructing element is an opaque layer (48), which is preferably arranged at one side of the at least one prism of the optical structure (46) and/or wherein the light obstructing element is a microlouver layer (54).

12. Transparent element according to any one of the preceding claims, wherein the transparent element (44) comprises at least one optical structure which controls the visibility of the information based on lenticular technology, wherein preferably the transparent element (44) comprises at least one, preferably semicircular, lens, wherein the lens is adapted to direct light to the information (34) dependent on the target object's (30) relative position.

13. Transparent element according to any one of the claims 4 to 2,

wherein the transparent element (44) comprises at least one optical structure which controls the visibility of the information based on holographic technology, wherein preferably the relative position of the target object (30) determines light amplitude and light phase reflected by the viewpoint dependent information device (40) so that one of the images is shown.

14. Transparent element according to any one of the preceding claims, wherein the transparent element (44) further comprises a protective layer for protecting the at least one optical structure, wherein the protective layer is preferably made from a material having a refractive index which is adapted to the optical structure, preferably has a refractive index similar to air. 5. Transparent element according to any one of the preceding claims, wherein the transparent element (44) is removably or irremovably attached or attachable to a host object (42) and/or the information (34).

16. Viewpoint dependent information device arranged or arrangeable at a mobile and/or immobile host object (42) comprising information (34) for a target object (30), wherein the information (34) is perceptible for the target object (30) in dependence on the target object's relative position to the host object (42), characterized in that the viewpoint dependent information device (40) comprises at least one transparent element (44, 54) according to any one of the preceding claims.

17. Viewpoint dependent information device according to claim 16

comprising a transparent element according to claim 10, wherein preferably the light obstructing element is at least one blind, preferably arranged at the circumference of the viewpoint dependent information device (40), obstructing the view onto the information (34) if the target object (30) is outside the boundaries of the information area.

18. Viewpoint dependent information device according to claim 17, wherein the at least one light obstructing element is mechanically and/or electrically adjustable for calibrating to the boundaries of the

information area.

19. Viewpoint dependent information device according to any one of the claims 6 to 18, wherein the viewpoint dependent information device (40) comprises a fluorescent material and/or a reflective material and/or a phosphorescent material and/or a chemoluminescent material.

20. Viewpoint dependent information device according to any one of the claims 6 to 19, wherein the viewpoint dependent information device (40) is illuminatable, preferably from a backside and/or preferably by means of at least one of: one or more lamps, one or more LEDs and one or more electroluminescent elements, such as an electroluminated elements, electroluminated panels or electroluminated wires.

21. Viewpoint dependent information device according to any one of the claims 16 to 20, wherein the information (34) is displayed on a computer display.

22. Viewpoint dependent information device according to any one of claims 20 to 21 , wherein the viewpoint dependent information device (40) is further adapted to be controlled such that an illumination of the viewpoint dependent information device (40) and/or an activation of the computer display is performed upon detection of a target object (30) entering or approaching the boundaries of the information area.

23. Viewpoint dependent information device according to any one of the claims 16 to 22, wherein the calibration to the boundaries of the information area is performed once during fitting up of the host object (42).

24. Viewpoint dependent information device according to any one of the claims 16 to 23, wherein the calibration to the boundaries of the information is performed, manually or automatically, if a change in the boundaries of the information area is to be expected, particularly dependent on a change in the host object's (42) environment.

25. Viewpoint dependent information device according to any one of the claims 16 to 24, wherein the viewpoint dependent information device (40) is individually manufactured for each host object (42) and/or for each type of host object (42) with substantially similar information areas.

26. Viewpoint dependent information device according to any one of the claims 16 to 25, wherein the host object (42) is a vehicle (10), such as a truck, a car, a bus, a construction equipment, an agricultural equipment, a train, a ship, or an aircraft, or a vehicle-trailer- combination, such as a truck-trailer-combination, a car-trailer- combination, particularly a car-caravan-combination, a bus-trailer- combination, particularly a bus-coach-combination, or a construction of agricultural equipment towing a trailer or tool, and wherein the information area is a blind spot area (1-8) of the vehicle (10) or vehicle- trailer-combination, wherein preferably the calibration to the blind spot area of the vehicle-trailer-combination is preformed automatically or manually, each time the vehicle-trailer-combination changes.

27. Viewpoint dependent information device according to any one of the claims 16 to 25, wherein the host object (42) is a mobile or moving object such as a moving machinery, particularly a vehicle, a moving machinery in a factory, or a robot, and the information area is an area in which it is potentially dangerous for a target object (30) to be present in.

28. Viewpoint dependent information device according to any one of claims 16 to 25, wherein the host object (42) is an at least temporarily immobile object such as a traffic sign, a sea mark, a navigation mark, a building, a part of a building, a road, any kind of landform, such as a rock or a tree, a scaffold, or a support structure.

29. Viewpoint dependent information device according to any one of the claims 16 to 28, further comprising an at least one detector element for detecting the presence of a target object (30) within or near the boundaries of the information area.

30. Viewpoint dependent information device according to claim 29, further comprising at least one sensor, particularly a camera, and/or a radar sensor, for detecting the target object (30).

31. Viewpoint dependent information device according to any one of the claim 16 to 30, wherein the viewpoint dependent information device (40) is arranged at a mechanical device, preferably a mechanical arm, which is controlled by a controller to display the viewpoint dependent information device upon detection of a target object (30) within or near the boundaries of the information area, preferably by extending or popping up.

32. Host object (42) comprising a transparent element (44, 54) according to any one of claims 1 to 15 and/or a viewpoint dependent information device (40) according to any one of claims 16 to 31.