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
  • G02B27/0149—Head-up displays characterised by mechanical features
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
  • G02B7/008—Mountings, adjusting means, or light-tight connections, for optical elements with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation

Definitions

• Assembly device suitable for assembling a screen with a partially transparent element and head-up display comprising such a device
• the present invention relates to techniques for assembling a screen with a partially transparent element, in particular for a vehicle head-up display.
• the principle of head-up displays is to project images, in particular useful for driving, directly into a driver's field of vision.
• head-up displays generally comprise an image generation device suitable for generating images and a device for projecting the generated images suitable for transmitting these images to a partially transparent blade placed in the field of vision of the driver, so that he can see these images and any information they contain without having to look away.
• This partially transparent blade is generally constituted either by the windshield of the vehicle, or by a dedicated combiner, placed between the windshield and the driver's eyes.
• Most of the image generation devices used today comprise a light source backlighting a screen (for example a screen of the TFT-LCD type) adapted to generate the images which are then transferred to an optical system generally comprising at least one magnifying mirror, before reaching the partially transparent blade.
• a screen for example a screen of the TFT-LCD type
• the head-up display comprises a box (generally opaque) which contains the image-generating device and the optical system in order to protect these elements against possible external attacks (dust, liquids, etc.).
• the screens in question absorb part of the light which backlights them, which causes them to heat up.
• the concentration rate of the solar flux is proportional to the magnification rate of the optical system of the head-up display. Indeed, the higher the magnification rate, the more the system is able to focus sunlight on the screen.
• partially transparent element of higher thermal conductivity than that of glass, directly plated on the screen in order to drain its heat towards a cold source.
• partially transparent elements can consist of a ceramic plate; for example, a single crystal (sapphire type in particular) is used.
• the ceramic plates can hardly be cut to the same size as the screen, which makes the assembly of the different layers relatively difficult. Added to this is the fact that the ceramic plate must always have perfect contact with a heat sink to facilitate heat drainage, which further complicates assembly.
• the centering of the screen with respect to the various surrounding optical elements is not easy to achieve.
• any deviation in the position of the screen has an impact on the shape of the virtual image; it may lose its rectangular shape and generate a distortion effect associated with a double image known as "Ghost Image”.
• the present invention proposes an assembly device suitable for assembling a screen comprising a central active part and a partially transparent element, with a contact face of said screen pressed against a contact face of said partially transparent element, characterized in that it comprises a support frame provided with a central opening suitable for positioning said central active part of said screen, which support frame comprises means for fixing said screen, and means for fixing said partially transparent element.
• Such an assembly device makes it possible to assemble the screen and the partially transparent element in a simple manner, with a minimum of constraints on the screen. It also facilitates the fixing of the screen and of the partially transparent element on a support structure (for example the case of the head-up display) and makes the centering of the screen simpler and more precise.
• said support frame comprises:
• Said screen receiving face may comprise said means for fixing said screen, and said partially transparent element receiving face may comprise said means for fixing said partially transparent element.
• said screen support plane is defined by two opposing plane parts arranged along a first axis
• said partially transparent element support plane is defined by two plane parts in opposition arranged along a second axis perpendicular to said first axis.
• said support frame may comprise (a) a recessed housing for said partially transparent element, the contour of which corresponds, except for clearance, to the contour of said partially transparent element, and (b) a housing embedding for said screen, the outline of which corresponds, except for clearance, to the outline of said screen.
• Said means for fixing said screen, and said means for fixing said partially transparent element may consist of elastic interlocking means of the type with a latching tab provided with a locking lug.
• the support frame may comprise at least two centering studs provided projecting from said partially transparent element receiving face, which centering studs are adapted to cooperate with mounting holes provided on a structure of support.
• the support frame may also comprise at least two fixing holes, each adapted for the passage of a clamping screw for fixing it to a support structure.
• the invention also proposes an image generating device comprising a light source producing a light beam and a screen through which the light beam passes and designed to modify the light beam so as to form an image, which generating device image device further comprises a partially transparent element through which the light beam passes and arranged to limit heating of said screen, and which image generating device further comprises a support structure provided with a window delimited by a window rim, on which around the window is fixed an assembly device as defined above, which assembly device supports said screen and said partially transparent element.
• the support structure may be provided with a window delimited by a window rim comprising mounting holes in which the centering tenons of said support frame fit.
• the support structure can also be provided with a window delimited by a window periphery comprising fixing holes for fixing said support frame by means of clamping screws.
• said support structure may consist of a heat sink, or is thermally connected to a heat sink.
• said support structure comprises an upstream face, oriented on the side of said light source, and a downstream face, oriented on the opposite side to said light source, said assembly device which supports said screen and said partially transparent element being fixed on said downstream face of said support structure, with said partially transparent element oriented in the direction of said light source.
• said support structure comprises an upstream face, oriented on the side of said light source, and a downstream face, oriented on the side opposite to said light source, said assembly device which supports said screen and said partially transparent element being attached to said upstream face of said support structure, with said partially transparent element oriented in the opposite direction to said light source.
• the invention also proposes a head-up display, for example intended to equip a motor vehicle, comprising an image generation device as proposed above, and an optical system adapted to transmit in the direction of a blade partially transparent images generated by said image generation device.
• the head-up display comprises a protective casing, which protective casing comprises said support structure provided with a window delimited by a window surround, on which window surround is fixed said device assembly supporting said screen and said partially transparent element.
• FIG. 1 schematically represents the main elements of a head-up display according to the invention
• FIG. 2 is a schematic perspective view of a possible embodiment of the assembly device according to the invention, seen from the side of its face intended to receive the screen;
• FIG. 3 is a schematic perspective view of the assembly device illustrated in FIG. 2, seen from the side of its face intended to receive the partially transparent element;
• FIGS. 2 and 3 is a schematic perspective view of the assembly device illustrated in FIGS. 2 and 3, on which the partially transparent element and the screen are assembled, seen here from the side where the partially transparent element is mounted;
• FIG. 5 is a schematic perspective view of the equipped assembly device, as illustrated in FIG. 4, seen here from the screen mounting side;
• FIG. 6 is a schematic view in perspective and in section which illustrates the assembly of the assembly device equipped with the screen and the partially transparent element, on a support structure;
• FIG. 7 schematically presents a possibility of mounting the assembly device equipped with the screen and the partially transparent element, on the protective case of a head-up display;
• FIG. 8 schematically presents another possibility of mounting the assembly device equipped with the screen and the partially transparent element, on the protective case of a head-up display.
• the head-up display 2 represented in FIG. 1 comprises an image-generating device 4, which generates an upstream light beam Fi, and an optical system 6, which receives this upstream light beam Fi as input and projects outputs a downstream light beam Ff in the direction of a partially transparent blade 7, here the windshield of a vehicle (typically a motor vehicle) fitted with the head-up display 2.
• the downstream light beam Ff is thus incident on the partially transparent blade 7 and partially reflected on this partially transparent blade 7 in the direction of the driver's eyes (schematically represented by the reference O in FIG. 1).
• the light beam (generated by the image generation device 4 and transmitted as just indicated to the driver's eyes O) represents an image to be displayed, which the driver will thus see beyond the partially transparent blade 7, in the environment (outside the vehicle) facing it, without having to look away.
• the virtual image thus seen by the driver has been represented under the reference I.
• the image generating device 4 comprises a light source 11 and a screen 12.
• the image generating device 4 again comprises here, between the light source 11 and the screen 12, a reflector 13 and a diffuser 14.
• the optical system 6 is formed here of two mirrors 15 etl6.
• the optical system 6 used here indeed comprises a first mirror (here a plane mirror) 15 placed opposite the image generating device 4 and a second mirror 16 (here a curved mirror, with a shape defined for example to obtain the sharp virtual image I).
• the optical system 6 can comprise a single mirror, or a plurality of other types of mirrors and/or other optical elements such as one or more lenses for example.
• the upstream light beam Fi is thus reflected on the first mirror 15 in the direction of the second mirror 16, then on the second mirror 16 in the direction of the partially transparent blade 7, as clearly visible in Figure 1.
• the head-up display 2 also comprises a casing 8 (generally opaque) which encloses the image-generating device 4 and the optical system 6, in particular in order to protect these elements against possible external attacks (dust, liquids , etc.).
• a casing 8 generally opaque which encloses the image-generating device 4 and the optical system 6, in particular in order to protect these elements against possible external attacks (dust, liquids , etc.).
• the housing 8 comprises an opening 10 through which passes the light beam projected by the optical system 6 in the direction of the partially transparent blade 7 (that is to say here the light beam reflected by the second mirror 16) .
• the opening 10 of the housing 8 is closed by a window 17 (sometimes called “cover window”) formed for example of a sheet of plastic material of the polycarbonate type with a thickness of between 0.25 mm and 0.75 mm.
• a window 17 (sometimes called “cover window") formed for example of a sheet of plastic material of the polycarbonate type with a thickness of between 0.25 mm and 0.75 mm.
• the partially transparent blade 7 can be a combiner dedicated to the head-up display 2, placed between the windshield of the vehicle and the eyes of the driver, on the path of the downstream light beam Ff.
• the light source 11 consists of one or more light-emitting diodes (or LEDs for "Light Emitting Diode”).
• This light source 11 backlights the screen 12 and the transmission of light from the light source 11 to the screen 12 has been represented by the orientation arrow L in Figure 1.
• the screen 12 here is a liquid crystal display (or LCD for "Liquid Crystal Display”), for example of the type with thin film transistors (or TFT for "Thin Film Transistor”).
• LCD liquid crystal display
• TFT thin film transistors
• Such an LCD screen 12 comprises an assembly of elements (or blades) in the form of plates, comprising in particular, in the direction of the path of the light L: an input polarizer, a matrix of liquid crystals and a polarizer Release.
• the input polarizer and the output polarizer of the screen 12 can be absorption polarizer filters (hence significant heating at the level of these polarizers).
• the input polarizer and the output polarizer of the screen 12 respectively have a first axis and a second axis perpendicular to each other (in the context of the so-called “normally off” technology, or NB for "normally black” ). It is recalled that the axis of a polarizer is the rectilinear polarization direction of the light beam after passing through the polarizer.
• the light beam between the input polarizer and the output polarizer will be polarized along the first axis (axis of the input polarizer) and no light will therefore be emitted at the output of the output polarizer.
• the polarization of certain parts of the light beam is modified at the level of the liquid crystal matrix so that the light is emitted at the output of the output polarizer at the regions corresponding to said portions of the light beam.
• these blades or plates constituting the input polarizer, the liquid crystal matrix and the output polarizer can be associated with other blades or plates, such as glass plate(s), matrix of colored or other elements.
• the screen 12 made up of its various blades or associated plates is in the form of a rectangular plate having a length which may be greater than 40 mm, a width which may be greater than 30 mm, and a thickness which may be greater than 1mm.
• This rectangular plate has two opposite flat faces.
• the screen 12 comprises a central active part 12a corresponding to the positioning of the liquid crystal matrix, bordered by a peripheral surround 12b. It also includes connectors (also called “LCD connector cable” or “TFT flex”), produced here in the form of electrical cables in a ribbon and not shown in FIG. 1, adapted to provide the screen 12 with its power supply and its control signals.
• LCD connector cable also called “TFT flex”
• FIG. 1 also shows the luminous flux Fs coming from the sun (hereinafter referred to as "solar flux Fs”), capable of entering the box 8 and coming to be concentrated on the screen 12 by effect magnifying glass due to the mirrors 15, 16 of the optical system 6, and therefore risking causing the screen 12 to overheat.
• solar flux Fs the luminous flux coming from the sun
• the image generation device 4 of the head-up display 2 comprises a partially transparency 18 associated with said screen 12.
• this partially transparent element 18 is in the form of a plate, one of the faces of which is placed in contact with one face of the screen 12, this partially transparent element 18 thus being adapted to limit, or even avoid, heating of said screen 12, and/or to evacuate at least part of the heat generated at the level of said screen 12.
• the partially transparent element 18 used is preferably a transparent ceramic, for example a single crystal such as sapphire.
• simple oxide MgO, Al2O3, ZrO2, Y2O3, SC2O3 or LU2O3
• complex oxide Y3Al5O12, MgAl2O4 or ZNAI2O4, even Lu 2 TiO3, Lu2Zr2O 7 , LusNbO?, LaGdZr 2 O 7 , Lag,33SisO
• This partially transparent element 18 is used in the form of a plate or blade having two opposite flat faces and the thickness of which can be between 0.5 and 3 mm (for example between 0.8 and 1.2 mm ).
• This plate or blade may have a rectangular shape, the length of which may be greater than or equal to 25 mm, and the width of which may also be greater than or equal to 25 mm.
• the partially transparent element 18 is chosen from materials having a thermal conductivity greater than 5 W/mK and preferably greater than 40 W/mK, in order to obtain good heat dissipation.
• the partially transparent character of the partially transparent element 18 (whose transmittance is advantageously between 80 and 90%) allows it to absorb part of the sunlight (of the order of 5% to 15% sunlight in the visible spectrum), thus protecting the screen 12.
• the partially transparent element 18 can also be chosen to absorb in the infrared to contribute to reducing the thermal load in this region of the solar light spectrum (for example the sapphire makes it possible to filter the infrared beyond 5 pm) .
• the screen 12 and the partially transparent element 18 are assembled by an assembly device 20, with a contact face of said screen 12 pressed against a face of contact with said partially transparent element 18, and this head-up display 2 comprises a support structure 22 on which said assembly device 20 is fixed.
• the support structure 22 is an integral part of the image generation device 4. It can be part of the box 8 of the head-up display 2, or be integrated into this box 8.
• FIGS. 4 and 5 show the two faces of the assembly device 20 equipped, one with the screen 12 and the other with the partially transparent element 18.
• the corresponding assembly device 20 comprises a support frame 201, as well as fixing means 202 for fixing the screen 12, and fixing means 203 for fixing the partially transparent element 18.
• the support frame 201 is of generally planar shape and it is provided with a central opening 2011, here rectangular, which is adapted to the positioning of the central active part 12a of the screen 12.
• This support frame 201 is delimited by an outer border 2012, an inner border 2013 (which defines the central opening 2011), a screen receiving face 2014 and a partially transparent element receiving face 2015 (located opposite the screen receiving face 2014).
• the screen receiving face 2014 of the support frame 201 (FIG. 2) comprises a mounting housing 204 arranged to receive the screen 12.
• the recessed housing 204 for the screen 12 is delimited by an outline 205 and by a screen support plane 206 against which a contact face of said screen 12 is intended to bear.
• the outline 205 of the mounting housing 204 corresponds, except for clearance, to the outline of the screen 12.
• these two outlines have a generally rectangular shape.
• the screen support plane 206 is defined by two plane parts 206a and 206b, in opposition, arranged along a first axis X on either side of the central opening 2011.
• the two plan parts 206a and 206b extend along the two long sides of the rectangular central opening 2011.
• the screen-receiving face 2014 comprises the aforementioned fixing means 202 of the screen 12.
• These fixing means 202 of the screen 12 consist of elastic interlocking means of the snap-in tongue type 2021 fitted with a locking pin 2022.
• These snap tabs 2021 are here 4 in number distributed around the periphery of the contour 205 of the mounting housing 204. They are each bordered by two lateral slots 2023 formed in the support frame 201 allowing their elasticity to be improved. .
• a notch 207 adapted to the passage of the connectors of the screen 12. This notch 207 extends the plane part 206b of the support plane screen 206 to the outer edge 2012 of the support frame 201.
• the partially transparent element receiving face 2015 of the support frame 201 (FIG. 3) comprises a mounting housing 208 arranged to receive the partially transparent element 18.
• the embedding housing 208 for the partially transparent element 18 is delimited by an outline 208a and by a partially transparent element support plane 209 against which a contact face of said partially transparent element 18 is intended to come take support.
• the outline 208a of the mounting housing 208 corresponds, except for clearance, to the outline of the partially transparent element 18.
• these two outlines have a generally rectangular shape.
• the partially transparent element support plane 209 is defined by two plane parts 209a and 209b, in opposition, arranged along a second axis Y on either side of the central opening 2011.
• the two plan parts 209a and 209b extend along the two short sides of the rectangular central opening 2011.
• the partially transparent element receiving face 2015 comprises the aforementioned means 203 for fixing the partially transparent element 18.
• These fixing means 203 for the partially transparent element 18 are similar to the fixing means 202 of the screen 12. They consist of elastic interlocking means of the snap-in tongue type 2031 provided with a locking lug 2032.
• These snap tabs 2031 are here 2 in number arranged vis-à-vis the edge of the plan parts 209a and 209b. In this case, they are placed approximately on the median axis of the length of the central opening 2011, that is to say centered or approximately centered on the width of the short sides of this central opening 2011.
• the partially transparent element support plane 209 is located in the same plane as the screen support plane 206.
• the dimension of the recessed housing 204 of the screen 12 and the dimension of the recessed housing 208 of the partially transparent element 18 are independent of each other and respectively adapted to the dimension of the screen 12 and that of the partially transparent element 18.
• the surface of the partially transparent element plate 18 is much greater than the central opening 2011 of the support frame 201.
• the support frame 201 therefore allows the fixing of the screen 12 on its screen receiving face 2014, and the fixing of the partially transparent element 18 on its partially transparent element receiving face 2015, with a contact face of said screen 12 pressed against a contact face of partially transparent element 18.
• the face of the partially transparent element 18 intended to be in contact with one face of the screen 12 can be one or the other of its two opposite flat faces.
• the face of the screen 12 intended to be in contact with a face of the partially transparent element 18 can be one or the other of its two opposite faces.
• the contact faces of the screen 12 and of the partially transparent element 18 are those which bear against the plane parts 206a and 206b, on the one hand, and on the parts of plan 209a and 209b, on the other hand.
• the support frame 201 further comprises centering studs 2016, projecting from the receiving face of the partially transparent element 2015, which are adapted to cooperate with recessed holes provided on the support structure 22 of the head-up display 2.
• These 2016 centering studs are here two in number, but there could be more of them. In the illustrated embodiment they are arranged on the short sides of the rectangular support frame 201.
• the support frame 201 also comprises fixing holes 2017 each adapted to the passage of a tightening screw for fixing the assembly device 20 on the support structure 22 of the head-up display 2.
• These 2017 fixing holes are here two in number, but they could be more numerous. In the illustrated embodiment they are arranged on the short sides of the rectangular support frame 201.
• the equipment of the assembly device 20 consists in positioning the partially transparent element 18 and the screen 12 in their respective recessed housing 208 and 204, on the dedicated faces 2015 and 2014 of the support frame 201, such as shown in Figures 4 and 5.
• the partially transparent element plate 18 is fitted or snapped into its recessed housing 208 by exerting a force separating the two locking lugs 2032 from the snap tabs 2031.
• the outline 208a of the mounting housing 208 which corresponds to the outline of the partially transparent element 18, ensures locking of the latter on the assembly device 20 without the possibility of movement. In position, this prevents the partially transparent element 18 from slipping under the effect of vibrations.
• the screen 12 is also nested or snapped into its recessed housing 204 by exerting a force separating the four locking lugs 2022 from the snap tabs 2021.
• the side of the screen 12 opposed to connectors 12c can be introduced under the lugs 2022 of the snap tabs 2021 opposite, then a force is applied to the opposite edge of the screen 12 to ensure its complete fitting into its recessed housing 204.
• the outline 205 of the mounting housing 204 which corresponds to the outline of the screen 12, ensures locking of the latter on the assembly device 20 without the possibility of movement. In situation, this prevents the screen 12 from slipping under the effect of vibrations.
• the support planes 206 and 209 are located in the same plane and thus designed in such a way that when the screen 12 and the partially transparent element 18 are positioned on the assembly device 20, the contact between them is direct and perfect (that is to say that their facing faces are perfectly applied one against the other).
• the fixing means 202 and 203 are designed so that they effectively clamp the screen 12 and the partially transparent element 18.
• a compact sub-assembly is thus obtained formed of the assembly device 20 equipped with the screen 12 and the partially transparent element 18, these last two elements being in tight and secure contact.
• films, blades or plates can be associated with the screen 12 and with the partially transparent element 18, such as for example polarizing films (reflective polarizers installed on the rear face of the screen 12 on the light source 11 side to recycle the light from the backlight) or infrared films (reflecting infrared films placed on the face of the screen 12 on the side of the optical system 6 to send back by reflection the infrared radiation of the sun which enters inside the head-up display).
• polarizing films reflective polarizers installed on the rear face of the screen 12 on the light source 11 side to recycle the light from the backlight
• infrared films reflecting infrared films placed on the face of the screen 12 on the side of the optical system 6 to send back by reflection the infrared radiation of the sun which enters inside the head-up display.
• the fixing means 202 and 203 will be adapted accordingly, to obtain optimum clamping of the various constituent elements of the stack.
• the assembly device 20 equipped with the screen 12 and the partially transparent element 18 is fixed to the support structure 22 of the head-up display 2 in the manner illustrated in FIG. 6.
• the support structure 22 is an integral part of the image generation device 4; and it can be part of the box 8 of the head-up display 2, or be integrated into this box 8.
• this support structure 22 consists of a heat sink, or is thermally connected to a dedicated heat sink, in order to ensure the heat dissipation function from the center of the screen 12.
• the support structure 22 consists of a wall of the box 8.
• This support structure 22 comprises a window 23 delimited by a window rim 24 on which the assembly device 20 is fixed.
• the periphery of the window 24 includes mounting holes 24a in which the centering studs 2016 of the support frame 201 are fitted. It also includes mounting holes 24b for fixing the support frame 201 by means of screws clamping 25. These fixing holes 24b can be tapped to avoid the use of a locking nut.
• the clamping screws 25 can be provided long enough to also assemble the reflector 13 from the outside of the box 8.
• the box 8 (and therefore the support structure 22) is preferably made of a material with a thermal conductivity greater than or equal to 15 W/m.K.
• the box 8 can be made of metal (aluminum, magnesium, steel, etc.).
• the active part 12a of the screen 12 is located opposite the window 23.
• the assembly device 20 thus makes it possible to center the screen 12 and the partially transparent element 18 with respect to their environment; it also makes it possible to assemble the screen 12, the partially transparent element 18 and also any additional films, and to guarantee good contact between them.
• the assembly device 20 is fixed to the support structure 22 depending on the thermal stress that is to be managed.
• the support structure 22 comprises an upstream face, oriented on the side of the light source 11, and a downstream face, oriented on the side opposite to this light source 11, then, as illustrated in Figure 7 , the assembly device 20 which supports the screen 12 and the partially transparent element 18, can be fixed on the downstream face of the support structure 22, with the partially transparent element 18 in contact with said support structure 22 and oriented towards the light source 11.
• the assembly device 20 is fixed inside the box 8, with the partially transparent element 18 placed on the side of the rear face of the screen 12 so that it faces the light source 11.
• the assembly device 20 which supports the screen 12 and the partially transparent element 18, can be fixed on the upstream face of the support structure 22, with the element partially transparent 18 in contact with said support structure 22 and oriented away from the light source 11.
• the assembly device 20 is fixed to the outside of the box 8, with the partially transparent element 18 placed on the side of the front face of the screen 12 so that it faces the solar light.

Applications Claiming Priority (2)

Publications (1)

Family

ID=74668936

Family Applications (1)

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Family Cites Families (5)

• 2020
  • 2020-10-26 FR FR2010969A patent/FR3115611B1/fr active Active
• 2021
  • 2021-10-26 EP EP21799042.3A patent/EP4232866A1/de active Pending
  • 2021-10-26 CN CN202180073449.9A patent/CN116438481A/zh active Pending
  • 2021-10-26 WO PCT/EP2021/079693 patent/WO2022090233A1/fr unknown

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