Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/01—Head-up displays
  • G02B27/0101—Head-up displays characterised by optical features
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
  • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
  • G02B26/0875—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more refracting elements
  • G02B26/0883—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more refracting elements the refracting element being a prism
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/01—Head-up displays
  • G02B27/0179—Display position adjusting means not related to the information to be displayed
  • G02B2027/0181—Adaptation to the pilot/driver

Definitions

• Imaqe generation unit and head-up display provided with such an image generation unit
• the present invention relates to an image generation unit, used in particular in a head-up display for a vehicle.
• an image generation unit comprising:
• a backlighting device comprising at least one light source and an optical system configured, from the light emitted by the source, to produce a light beam for illuminating the screen.
• the invention also relates to a head-up display comprising such an image generation unit.
• the invention applies particularly advantageously in the case where it is desired to adjust the position of an eye zone, at the level of which a user must place his eye in order to be able to visualize the image produced by the generating unit. picture.
• an optical projection system for projecting the light beam coming from the screen of this image generation unit into a partially transparent plate disposed in front of the driver's eyes (made for example by means of the windshield of the vehicle), so as to form, by reflection by said blade, a virtual image of the screen.
• the virtual image comprising the information to be displayed, is then superimposed visually on the environment facing the vehicle.
• zone ocular an area of space, called here zone ocular, reached, at the output of the display, by at least a portion of the light beam emitted by the screen of the image generation unit (this ocular zone corresponds for example to the exit pupil of the display) .
• the present invention provides an image generation unit as defined in the introduction, further comprising adjustment means for changing the orientation of the illumination light beam with respect to the screen, said adjusting means leaving said source fixed with respect to said optical system.
• the adjustment means mentioned above may for example comprise a pivot link allowing a rotation of the entire backlight device relative to the screen.
• the adjustment means may also comprise a prism arranged in the path of the illumination light beam, between the backlight device and the screen, the prism being rotatably mounted relative to the screen about an axis of rotation.
• the structure of the image generation unit is advantageously simple and compact. In particular, it is more compact than in the case of an orientation adjustment of the illumination light beam produced by means of a pivoting plane mirror.
• the axis of rotation of the prism is parallel to a ridge of the prism
• a distance separating the prism from the screen is less than a predetermined maximum deviation
• the illuminating light beam extends transversely over a given width, and said maximum deviation is equal to said width;
• said maximum deviation is less than half said width
• the optical system of the backlight device comprises a reflector by means of which is produced the light beam of illumination;
• the screen is a liquid crystal display
• the screen comprises an active zone for the generation of the image, and said given width on which the illumination light beam extends transversely is less than one dimension of the active zone of the screen.
• the invention also provides a head-up display comprising an image generation unit as described above.
• the head-up display further comprises an optical projection system, for projecting the light beam coming from the screen of the image generation unit towards a partially transparent blade, so as to form, by reflection by said blade, a virtual image of the screen.
• the screen of the image generation unit is fixed relative to the projection optical system, even when the average direction of the illumination light beam is changed relative to the screen.
• a change in the average direction of the illumination light beam makes it possible, in the display, to adjust the position of the aforementioned ocular zone, while maintaining the virtual image (of the screen) fixed in the environment viewed through the blade.
• the projection optical system is corrected by at least one optical aberration (such as geometric aberration), said correction being optimized for a given position of the screen with respect to the optical system.
• at least one optical aberration such as geometric aberration
• FIG. 1 shows schematically a head-up display comprising an image generation unit which implements the teachings of the invention
• FIG. 2 shows schematically, in more detail, the image generation unit of Figure 1;
• FIG. 3 schematically shows an image generation unit according to another embodiment
• FIG. 4 schematically shows an image generation unit according to yet another embodiment.
• Figure 1 shows schematically a display 1 head high, intended to equip a vehicle, for example a motor vehicle, a train, a boat such as a barge, a tram or a bus.
• a vehicle for example a motor vehicle, a train, a boat such as a barge, a tram or a bus.
• the display 1 comprises an image generation unit for generating an image to be displayed.
• the generation unit 10; 10 '; 10 "comprises a screen 12, electrically controllable to generate the image to be displayed This screen 12 is for example made by means of a liquid crystal screen.
• the display 1 also comprises, here, a projection optical system, for projecting the light beam F 'which emerges from the screen 12 to a partially transparent strip 2.
• the blade 2 then reflects at least part of this light beam to the eyes of a user of the display, here to the eyes of the driver of the vehicle.
• the projection optical system here comprises a folding mirror 3 and a concave mirror 4, arranged in the optical path of the light beam F ', between the screen 1 1 and the partially transparent plate 2.
• the partially transparent blade is formed here by the windshield of the vehicle (which bears the reference 2 in Figure 1).
• a dedicated component called combiner, disposed between the windshield of the vehicle and the eyes of the driver.
• the optical projection system forms, with the blade 2, a virtual image of the screen 12. This virtual image is formed relative to the blade 2, the opposite of the user.
• the blade 2 is partially transparent, it allows the user to visualize an environment, for example a road environment, through the blade.
• the virtual image is visually superimposed on this environment, so that the user can view it without distracting from the environment.
• the display 1 may comprise, downstream of the screen 12, one or more optional optical components (not shown), such as a protection window or a polarizing filter.
• the projection optical system could comprise a different number of mirrors, or optical components.
• the projection optical system could comprise a single mirror.
• eye zone ZO or eye box, literal translation of the word "eyebox”"used in English
• This eye area is sometimes referred to as the Anglo-Saxon eye-box.
• the light beam F 'coming from the screen 12 has, immediately at the output of this screen, a mean direction of propagation x 0 .
• This mean direction of propagation x 0 corresponds to the direction of the main light ray emerging from the screen 12, or, otherwise formulated, to the mean direction defined by the radiation indicator at the output of the screen 12.
• the image generation unit 10; 10 '; 10 " which will be described in detail below, is configured to allow adjustment of this mean propagation direction x 0 (or, otherwise formulated, a setting of the orientation of the light beam F 'coming out of the screen). This direction makes it possible to move the ocular zone ZO, and to bring it thus vis-à-vis one of the eyes of the user.
• This setting also makes the display compatible with different height settings of the driver's seat.
• the image generation unit 10; 10 '; 10 is more precisely configured to allow this adjustment of the orientation of the light beam F 'coming out of the screen 12, while leaving this screen 12 fixed with respect to the projection optical system (in terms of position as well as orientation).
• the virtual image of the screen is formed in the same position, in the environment facing the vehicle, regardless of the position setting of the eye area.
• the display 1 is configured to operate in a so-called augmented reality mode in which the elements to be displayed, for example a light line for underlining or materializing a running lane border, must superimpose on given elements of the environment viewed through the blade 2.
• the elements to be displayed for example a light line for underlining or materializing a running lane border
• the concave mirror 4 of the projection optical system is corrected here with at least one optical aberration, such as a geometric aberration.
• This correction is optimized for a given position and orientation of the screen 12. It is therefore particularly interesting, in terms of the quality of formation of the virtual image, that, as here, the screen remains positioned at this position. given and retains said given orientation.
• the projection optical system be omitted, the image generation unit then being oriented so as to directly direct the light beam coming from the screen towards the partially transparent blade made by means of a combiner. In the context of this variant, it can then be provided that, when the orientation of the light beam coming out of the screen is changed, the screen nevertheless remains fixed (in terms of position as well as orientation) with respect to to the combiner.
• the image generation unit 10; 10 '; 10 “comprises, in addition to the screen 12 mentioned above, a backlighting device 1 1 comprising:
• At least one source of light here several, and
• an optical system configured, from the light emitted by these sources 1 10, to produce a lighting light beam F of the screen 12.
• the light sources 1 10 are made here by means of light-emitting diodes.
• the optical system comprises a reflector 1 13, and, optionally, a diffuser 1 14.
• the reflector comprises reflecting lateral walls shaped, by reflection, to direct the light emitted by the sources 1 10 in the same direction x given.
• the reflector thus makes it possible to collimate the light emitted by the sources 1 10.
• the diffuser 11 made for example by means of a film having a smooth face and an opposite grained face, diffuses the light that it receives into a cone of diffusion of reduced angular aperture, for example less than 30 degrees.
• a non-conical diffusion but more important in one direction than in the other, for example a diffusion 20 ° x 40 ° (diffusion in a solid angle of width 20 ° in a first direction and width 40 ° in a second direction perpendicular to the first direction).
• the illumination light beam F finally delivered by the backlighting device 1 1 is generally collimated, c 'i.e. formed of substantially light rays parallel to each other.
• the reflective walls of the reflector 1 13 are shaped here so that the illumination light beam F has the most uniform light intensity possible (in a section of this beam).
• the diffuser 1 14 further improves the homogeneity of the light intensity within this beam.
• the backlight device 1 1 also comprises a printed circuit board 1 1 1 for mounting and power supply sources 1 10, and means for discharging the thermal energy released by these sources 1 10, such only cooling fins 1 12.
• the image generation unit 10; 10 '; 10 “comprises adjustment means for modifying the orientation of the illumination light beam F with respect to the screen 12, these adjustment means leaving the sources 1 10 fixed with respect to the optical system of the backlighting device.
• the mean direction x, of the illumination light beam F, the orientation of which is modified by the adjustment means, is the average direction presented by this light beam immediately upstream of the screen 12 (that is to say just before the screen 12, from the point of view of the direction of propagation of this light beam).
• the adjustment means thus allow a modification of the angle of incidence i 2 formed between the mean direction x, of the illumination light beam F, and a direction normal to the screen 12.
• the average direction xo of the light beam F 'coming out of the screen 12 depends directly on the average direction x, the illumination light beam F incident on this screen.
• these two directions x, and x 0 are even identical (the liquid crystal screen does not deviate the light beam passing through it).
• the adjustment means of the image generation unit 10; 10 '; 10 "thus make it possible to modify the mean direction x 0 of the light beam F coming out of the screen 12, and thus to modify the position of the ocular zone ZO with respect to the display 1.
• the illumination light beam F advantageously retains the same characteristics, in particular its level of homogeneity. lighting, which has been optimized here thanks to shape of the reflector 1 13.
• the image generation unit 10; 10 '; 10 "actually makes it possible to modify the orientation of the average direction x 0 of the light beam F 'which leaves the screen 12, while keeping the screen 12 fixed with respect to the display 1 (which, as explained above , is particularly interesting in practice).
• the adjustment means of the image generation unit 10 comprise a prism 13 disposed in the path of the light beam of FIG. illumination F, between the backlighting device 1 1 and the screen 12.
• the prism 13 deflects the illuminating beam of illumination F.
• the mean direction x of the illumination light beam F at the input of the prism 13 (which corresponds to the average direction of this beam at the output of the backlighting device 1 1)
• the prism 13 is rotatably mounted relative to the screen 12 about an axis of rotation z. It has an inlet face 131 and an outlet face 132 defining between them a stop 133.
• the axis of rotation z of the prism is parallel to this stop 133 (that is to say parallel to the generatrix of the prism).
• a rotation of the prism 13 around its axis of rotation z modifies the angle of incidence formed between the mean direction x of the illumination light beam F incident on the prism 13, and a direction normal to the entry face 131 of the prism.
• the deflection angle D introduced by the prism 13 depends on this angle of incidence.
• a rotation of the prism 13 around its axis of rotation z thus makes it possible to modify the deflection angle D, and thus to adjust the mean direction x, of the light beam of FIG. F lighting incident on screen 12.
• the prism 13 is formed for example of a transparent plastic material, to reduce its cost, its weight and its fragility compared to a glass prism.
• the prism is more precisely formed of a material of the polymethyl methacrylate (PMMA) type, whose refractive index n is equal, on average over all wavelengths of the visible, to about 1, 5 .
• PMMA polymethyl methacrylate
• it could be a transparent polycarbonate, or a cyclic olefin polymer or copolymer (such as Zeonex).
• An antireflection treatment may be applied on the entry face 131 and the exit face 132 of the prism 13, so that the introduction of the prism into the path of the illumination light beam only induces a minimal power loss for this beam.
• the aperture angle a of the prism 13, formed between its input faces 131 and exit 132, may for example be between 8 degrees and 30 degrees. It is here equal to 24 degrees.
• the rotation of the prism makes it possible to move the ocular zone ZO over a given distance, upwards or downwards, with respect to a reference position of this ocular zone.
• This distance d is here equal to 6 centimeters, to allow the position of the ocular zone to be adapted to a wide range of users having different sizes.
• the illumination light beam F comes out of the prism with a mean direction x, forming an angle
• the illumination light beam F comes out of the prism with a mean direction x, making an angle - max with the reference direction x ref .
• these two extreme angular positions of the prism correspond to an angle of incidence, respectively equal to 0 degrees, and 20 degrees.
• a rotation amplitude of the 20 degree prism is therefore necessary here to obtain the desired displacement amplitude of the ocular zone Z0 (here 60 mm).
• the prism 13 is movable continuously, in rotation about its axis of rotation z, between these two extreme angular positions. It can also be expected that it can occupy a number of discrete angular positions, for example the number of 20, between these two extreme angular positions.
• the various light rays of this beam are incident on the prism 13 substantially with the same angle of incidence H, and are thus deflected by the prism of the same deviation angle D.
• This distance e is for example equal to the distance separating the prism from the screen where they are closest to each other.
• the maximum deviation e ma x may be equal to a transverse width l_F presented by the illumination light beam F.
• the (lateral) displacement of the the screen 12 illuminated by this beam remains negligible compared to the extent of this illuminated area.
• this maximum gap e ma x is equal to half the transverse width L F of the light beam.
• the screen is disposed downstream of the prism without an optical component intermediate between the prism and the screen, which allows positioning of the prism 13 as close to the screen 12 (so as not to overload FIG. this figure is not represented on the scale, and the distance separating the prism 13 from the screen 12 is exaggerated in relation to the reality).
• the backlighting device 1 1 is such that, here, the transverse width L F on which this light beam extends (in the plane of the screen) is less than one dimension L 2 of an active area of the screen.
• This active area of the screen corresponds to the region of this screen at any point from which it is possible to generate an image. This is the area occupied by the pixels of the screen (electrically controllable).
• 2 of this active zone, greater than the transverse width L F of the beam, corresponds to the width of this active zone, in the plane of the screen 12, perpendicular to the axis of rotation z of the prism.
• this active zone is wider than the area of the screen 12 illuminated by the illumination light beam F, it is possible here to generate an image at this illuminated zone, even when this illuminated zone is moving relative to the screen because of the orientation adjustment of the illumination light beam.
• the illumination light beam is wide, it is mainly at the periphery of this light beam that the chromatic dispersion introduced by the prism 13 modifies the chromatic properties of the beam.
• the chromatic dispersion introduced by the prism 13 modifies the chromatic properties of the beam.
• the means for adjusting the orientation of the illumination light beam F comprise a pivot connection allowing rotation of the assembly. of the backlighting device 1 1 relative to the screen 12, rather than the prism described above (this prism is then omitted).
• the image generation unit 10 ' is configured to allow an amplitude of rotation of the backlighting device 1 1 of plus or minus max, that is to say, plus or minus 4 degrees (the extreme angle max has been defined above) about the axis of rotation z 'defined by this pivot connection.
• This axis of rotation z ' is parallel to the screen 12 of the image generation unit 10'. As shown in FIG. 3, this axis of rotation z 'is situated at the level of the screen: it extends in the plane defined by an exit face of this screen. Positioning the axis of rotation z 'of the backlighting device 1 1 at the level of the screen 12 makes it possible to effectively reduce the displacement of the illuminated area of the screen, generated by a change in the orientation of the light beam. F. lighting
• the backlighting device 1 1 is disposed as close as possible to the screen 12, and that it is configured so that the lighting light beam extends transversely over a width L F less than the dimension L-
• the means for adjusting the orientation of the illumination light beam F comprise at the same time:
• the change in orientation of the illumination light beam F is then obtained by combining a rotation of the premium 13 around its axis of rotation z, and an overall rotation of the backlight device 11 around its axis of rotation. z '. Combining these two rotations makes it possible, for an orientation modification of the given illumination light beam F, to reduce the corresponding rotational amplitudes for the prism and the backlighting device.
• the orientation change of the illumination light beam F can be obtained in a shorter time than when only a pivoting of the prism, or backlighting device is employed.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Instrument Panels (AREA)
• Devices For Indicating Variable Information By Combining Individual Elements (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=60450774

Family Applications (1)

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Family Cites Families (5)

• 2017
  • 2017-07-31 FR FR1757309A patent/FR3069655B1/fr active Active
• 2018
  • 2018-07-31 WO PCT/EP2018/070804 patent/WO2019025470A1/fr unknown
  • 2018-07-31 EP EP18750153.1A patent/EP3662318A1/de not_active Withdrawn

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