Abstract:
The invention relates to a head-up display device that includes a retractable combiner having a display position and a storage position; and an actuating mechanism for moving the combiner from its storage position to its display position and vice versa. The mechanism comprises a lifter carriage bearing the combiner. The combiner is arranged standing on the lifter carriage. The lifter carriage executes a motion only in translation in order to reposition the combiner. A shutter element is provided in order to shut the deployment aperture. The shutter element is connected to the actuating mechanism so as to close or open the deployment aperture during at least part of the motion in translation of the lifter carriage.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit under 35 U.S.C. §371 of published PCT Patent Application Number PCT/EP 2012/073716, filed Nov. 27, 2012, claiming priority to French patent application number FR1160859 filed on 28 Nov. 2011, and published as WO2013/079479 on Jun. 6, 2013, the entire contents of which is hereby incorporated by reference herein. 
     
    
     TECHNICAL FIELD OF INVENTION 
       [0002]    The invention relates to a head-up display device, in particular for motor vehicles, lorries, buses, trains, aircraft etc. In particular, the invention relates to a head-up display device with retractable combiner. 
       BACKGROUND OF INVENTION 
       [0003]    A head-up display device typically includes a projection unit which produces a light beam intended to be directed towards a combiner in order to project images, in particular operating or driving information of a vehicle, in the form of a virtual image, in the field of view of the user, in particular of a pilot or driver of a motor vehicle. 
         [0004]    Originally designed for the display of information to pilots of combat aircraft, head-up display devices have today found their place in particular in the motor vehicle sector, more particularly in medium and high range cars. Head-up display devices are said to contribute to car safety as they allow drivers to read information without their eyes leaving the road in front of them. The virtual image containing the information displayed is in addition projected at a distance of some meters in front of the driver which allows him to read the information without modifying the accommodation of his eyes. 
         [0005]    Head-up display devices exist which use a part of the windscreen as a combiner, i.e. as the optical element which combines the light beam containing the information having to be presented to the user with the light emanating from the environment. Other head-up display devices include a combiner independent of the windscreen. Such a combiner comprises a plate having the necessary optical properties to deviate at least a substantial part of the beam emanating from the projection unit towards the user, while being sufficiently transparent to simultaneously allow the passage of a substantial part of the ambient light emanating from the environment. 
         [0006]    It has proved desirable to be able to protect the optical elements of the head-up display device, for example from ultraviolet rays which reduce their lifetime, dust, water and other damaging influences, risking deterioration of the projection quality. 
         [0007]    U.S. Pat. No. 5,394,203 describes a head-up display device comprising a combiner in the form of a reflective plate mounted tiltably and acting as a cover which is closed when the device is not in use. However, given that the plate acts as a cover, one of its sides remains exposed to the damaging influences. In the embodiment shown in the figures, the background of the plate is opaque, which obliges the driver to look at the road over the plate and which therefore greatly reduces the field of view of the driver. A similar device is shown in European patent application EP 2 093 094. 
         [0008]    Application WO 2007/057608 presents a head-up display device with retractable combiner. The combiner is mounted on a movable support so as to be able to be displaced between a display position, in which the combiner is upright in front of the user, and a storage position, in which the combiner is returned into the case which protects the whole of the optical and mechanical components of the head-up display device. 
         [0009]    However, a disadvantage of the head-up display device of application WO 2007/057608 is that the combiner sweeps through a considerable space on its deployment. In particular, the combiner is firstly displaced essentially horizontally in the direction of the windscreen, and is then lifted at its limit of travel. So that the combiner does not touch the windscreen, it is therefore necessary to install the whole of the head-up display device at a greater distance from the windscreen. 
         [0010]    An objective of the invention is to propose a head-up display device the combiner of which presents a smaller movement envelope (i.e. the space passed through by the combiner during its deployment or its retraction). 
       SUMMARY OF THE INVENTION 
       [0011]    A head-up display device comprises a projector to generate a light beam loaded with information to be displayed, a retractable combiner having a display position to display the information in the field of view of a user and a storage position, an optical system defining an optical path between the projector and the combiner when the latter is in its display position and an actuation mechanism to displace the combiner from its storage position into its display position and vice versa. The display position and the storage position are respectively on either side of an opening for deployment of the combiner. In accordance with one aspect of the invention, the actuation mechanism comprises a lifting carriage carrying the combiner. The combiner is arranged upright (i.e. essentially vertical, the angle between the vertical and the combiner being 25° at the maximum) on the lifting carriage. The actuation mechanism is so configured that the lifting carriage executes a travel solely in translation to move the combiner between its storage position and its display position. The head-up display device comprises in addition a closure element (e.g. a shutter, a clapper, a cover etc.) to close the deployment opening when the combiner is in its storage position. The closure element is linked to the actuation mechanism so as to close, open respectively the deployment opening during at least a part of the travel in translation of the lifting carriage. In other words, the closure element is displaced between the position of closure and the position of opening of the deployment opening at the same time as the lifting carriage is displaced over at least a part of its travel in translation. 
         [0012]    In accordance with the invention, the combiner is mounted pivotably on the lifting carriage so that, in the display position of the combiner, the direction in which the combiner sends back the light beam loaded with the information to be displayed can be adjusted. Preferably, the combiner is kept upright on the lifting carriage by spring means. The combiner coming into abutment against a stop when it has reached its display position, the lifting carriage bears against the spring means at the end of its travel in translation and thus causes the combiner to pivot. To adjust the direction in which the combiner sends back the light beam loaded with the information to be displayed, the limit of travel of the carriage is adjustable. 
         [0013]    Preferably, the actuation mechanism includes a guiding means, e.g. a rail, a rod, a groove, etc., defining the trajectory of the lifting carriage. 
         [0014]    The actuation mechanism preferably includes a driving means, e.g. an electric motor. 
         [0015]    In accordance with an advantageous embodiment of the invention, the lifting carriage is displaceable in translation by means of a drive screw transmission, a belt transmission, a cord or a rack and pinion transmission. 
         [0016]    The closure element preferably comprises an actuation arm and can pivot about an axis, the actuation arm cooperating with the lifting carriage through at least one slideway, the at least one slideway having a layout so designed that the closure element pivots about its axis during the at least one part of the travel in translation of the lifting carriage. 
         [0017]    In accordance with a preferred embodiment of the invention, the optical path between the projector and the combiner when the latter is in its display position passes through the deployment opening of the combiner and the closure element protects the exposed optical elements from water and dust. 
         [0018]    In accordance with another preferred embodiment of the invention, the optical path between the projector and the combiner when the latter is in its display position passes through a second opening. This second opening can preferably be closed by a second closure element, the second closure element being linked to the actuation mechanism so as to close or open the second opening during at least a part of the travel in translation of the lifting carriage. The second closure element is preferably mounted pivotably and linked to the closure element of the deployment opening so as to be driven simultaneously with the closure element of the deployment opening. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0019]    Other features and characteristics of the invention will become apparent from the detailed description of some advantageous embodiments presented below, by way of illustration, with reference to the attached drawings. These show: 
           [0020]      FIG. 1 : a side view of a head-up display device in accordance with a first embodiment of the invention, the combiner being in its storage position; 
           [0021]      FIG. 2 : a side view of the device of  FIG. 1 , the combiner being in its display position; 
           [0022]      FIG. 3 : a three-dimensional view of a head-up display device in accordance with a second embodiment of the invention, the combiner being in its storage position; 
           [0023]      FIG. 4 : a three-dimensional view of the device of  FIG. 3 , the combiner being in an intermediate position between the storage position and the display position; 
           [0024]      FIG. 5 : a three-dimensional view of the device of  FIG. 3 , the combiner being in the display position; 
           [0025]      FIG. 6 : a side view of a head-up display device in accordance with a second embodiment of the invention; 
           [0026]      FIGS. 7 to 10 : sections in the vertical plane including the pivoting axis of the combiner of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0027]      FIGS. 1 and 2  show, diagrammatically, a head-up display device  10  in accordance with a first embodiment of the invention. The device  10  includes a system for retraction of the combiner.  FIG. 1  shows the device  10  in its inactive position (combiner  20  in storage position) while  FIG. 2  shows the device  10  in the active position (combiner  20  in display position). 
         [0028]    The device  10  includes a projector  12  to generate a light beam loaded with the image representing the information to be displayed to the driver of the vehicle. The projector  12  includes a liquid crystal display  14  and a light source  16  (coherent or non-coherent, depending on the type of combiner, which can be diffractive or reflective) producing a backlighting light beam. The liquid crystal display  14  operates as a spatial light modulator and produces the image which will be displayed to the driver. The optical path between the projector  12  and the display position of the combiner  20  is defined by an optical system. In the example shown, this comprises a plurality of deviation mirrors  18  which send back the light beam from the projector  12  onto the combiner  20 , when the latter is in its display position ( FIG. 2 ). 
         [0029]    During the operation of the device  10 , the light beam loaded with the image generated by the liquid crystal display  14  is deviated towards the driver of the vehicle by the combiner  20 . Consequently, from the viewpoint of the driver, the image appears as a virtual image behind the combiner  20 , on the driver&#39;s eye—combiner axis  21 . The combiner  20  of  FIGS. 1 and 2  is of the transmission type. 
         [0030]    The combiner  20  is retractable by means of a retraction system (actuation mechanism), discussed in more detail below. In addition to its display position, the combiner  20  has a storage position inside the case (not shown) of the head-up display device  10 . The combiner  20  is mounted upright on a lifting carriage  22  which displaces it between the display and storage positions. The lifting carriage  22  is configured to execute a travel in vertical translation. The trajectory of the lifting carriage  22  is defined by guiding means (not shown in  FIGS. 1 and 2 ) which can comprise rails, rods or any other suitable guiding means. The lifting carriage is driven via a drive screw (worm) transmission by an electric motor  24 . The motor is coupled to the drive screw  26  by a belt transmission  28 . When the motor  24  is running, the drive screw rotates on itself. The lifting carriage  22  includes a nut  30  engaged on the drive screw  26 . 
         [0031]    To protect the inside of the case of the head-up display device  10  (e.g. from dust), the deployment opening of the combiner and the opening allowing the light beam to exit the case can be closed by respective closure elements  32 ,  34 . 
         [0032]    The closure element  32  of the deployment opening of the combiner is in the form of a clack mounted to pivot about an axis  36 . The clack  32  is attached to an actuation arm  38  provided with a slideway  40  cooperating with a sliding piece  42  of the lifting carriage  22 . The layout of the slideway  40  is so formed that the sliding piece  42 , which is displaced in vertical translation with the lifting carriage  22 , causes pivoting of the actuation arm  38  and therefore of the clack  32  about the axis  36  during at least a part of the travel of the lifting carriage  22 . 
         [0033]    It will be noted, in particular, that the slideway  40  is so formed that the clack  32  is out of the path of the combiner  20  before the upper edge of the latter has reached the level of the opening. In the storage position of the combiner, the upper edge of the combiner  20  is at a certain distance d from the clack  32 . Consequently, the section  44  of the slideway which the sliding piece  42  travels over the distance d at the start of the travel between the storage position and the display position of the combiner  20  has a form such that the clack  32  is tipped entirely out of the path of the combiner  20 . 
         [0034]    The closure element  34  is also linked to the retraction system, more particularly to the actuation arm  38 . The closure element  34  is so mounted as to pivot about an axis  46  by at least one arm  52 . The actuation arm  38  of the clack  32  acts as its actuator. When the actuation arm  38  is moved about the axis  36 , it rotates the closure element  34  about its axis  46 . In the example shown, the mechanical linkage between the actuation arm  38  and the closure element  34  is provided by a sliding piece  48 , fixed to the actuation arm  38 , which slides in a slideway  50  formed in the arm  52  of the closure element  34 . 
         [0035]      FIGS. 3 ,  4 , and  5  show three-dimensional views of the functional elements of interest to the invention of a head-up display device  110  in accordance with a second embodiment of the invention. 
         [0036]    The device  110  includes a projector  112  to generate a light beam loaded with the image representing the information to be displayed. The projector  112  includes a liquid crystal display  114  and a light source  116  (coherent or non-coherent, depending on the type of combiner, which can be diffractive or reflective) producing a backlighting light beam. The liquid crystal display  114  acts as a spatial light modulator and produces the image which will be displayed to the driver. The optical path between the projector  112  and the display position of the combiner  120  is defined by an optical system. In the example of  FIGS. 3 to 5 , the optical system comprises a deviation minor  122  which sends back the light beam from the projector  112  onto the combiner  20 , when the latter is in its display position ( FIG. 5 ). 
         [0037]    The combiner  120  is retractable by means of an actuation mechanism. In addition to its display position, the combiner  120  has a storage position inside the case (not shown) of the head-up display device  110 . The combiner  120  is mounted upright on a lifting carriage  122  which displaces it between the storage ( FIG. 3 ) and display ( FIG. 5 ) positions.  FIG. 4  shows an intermediate position. The lifting carriage  122  is configured to execute a travel in vertical translation. The trajectory of the lifting carriage  122  is defined by guiding means (not shown in  FIGS. 3 to 5 ) which can comprise rails, rods or any other suitable guiding means. The lifting carriage  122  is driven via a drive screw transmission by an electric motor  124 . The motor  124  is coupled to the drive screw  126  by a belt transmission  128 . When the motor  124  is running, the drive screw  126  rotates about itself. The lifting carriage  122  includes a nut  130  engaged on the drive screw  126 . 
         [0038]    During the operation of the device  110 , the light beam loaded with the image generated by the liquid crystal display  114  is deviated towards the driver of the vehicle by the combiner  120 . Consequently, from the viewpoint of the driver, the image appears as a virtual image behind the combiner  120 , on the driver&#39;s eye—combiner axis. The combiner  120  of  FIGS. 3 to 5  is of the reflective type. 
         [0039]    Contrarily to the embodiment of  FIGS. 1 and 2 , the device of  FIGS. 3 to 5  presents a common opening for the deployment of the combiner and the passage of the light beam. Consequently, a single closure element  132  is sufficient. The closure element is only shown partially in  FIG. 3  in order not to hide the components situated behind it. 
         [0040]    The closure element  132  is formed as a clack mounted pivotably about an axis  136 . The clack  132  is attached to an actuation arm  138  which cooperates with the lifting carriage  122  via a mechanism with slideways. The lifting carriage  122  is in particular provided with a sliding piece  142  cooperating with a slideway  140  of the linking piece  143 . The layout of the slideway  140  is so formed that the sliding piece  142 , which is displaced in vertical translation with the lifting carriage  122 , causes the linking piece  143  to pivot relative to the case (not shown) about the axis  145 . The linking piece  143  being linked to the actuation arm  138  via the sliding piece  147  and the slideway  149  therefore causes the clack  132  to pivot about the axis  136  during at least a part of the travel of the lifting carriage  122 . 
         [0041]    As in the preceding embodiment, the movements of the combiner  120   122  and of the clack  132  are coordinated that there is no conflict (i.e. the clack  132  is moved out of the path of the combiner  120  before the upper edge of the latter has reached the level of the deployment opening.) 
         [0042]    The combiner  120  is fixed to a combiner support  154  which is pivotable on the lifting carriage  122 . The combiner support  154  is prestressed into a certain position relative to the lifting carriage  122  by a spring (not shown in  FIGS. 3 to 5 ), which allows the combiner  120  to be kept upright on the lifting carriage  122 . When the display position of the combiner is reached, the combiner support  154  comes into abutment against one or more stops  156  (fixed relative to the case). At the limit of upward travel, the lifting carriage  122  bears against the spring which keeps the combiner  120  upright. It thus causes the combiner  120  to pivot by an angle dependent on its limit of travel. Consequently, the angle of tilt of the combiner  120  in the display position can be adjusted by adjustment of the limit of travel of the lifting carriage  122 . 
         [0043]    It should be noted that the same principle of adjustment of the tilt of the combiner can be used in the embodiment of  FIGS. 1 and 2 . 
         [0044]    It will be appreciated that the invention considerably reduces the volume (the space) necessary for the deployment of the combiner, and, consequently, the complexity of integration of a head-up display device. The integration of a head-up display device between the dashboard and the windscreen of a motor vehicle is therefore facilitated in comparison with the head-up display devices of the state of the art. 
         [0045]      FIGS. 6 to 10  show a detail of a head-up display device  210  in accordance with a particularly advantageous embodiment of the invention, derived from the embodiment of  FIGS. 3 to 5 .  FIG. 6  shows a side view of the head-up display device  210  when the lifting carriage  222  and the combiner  220  are in the last part of their translation trajectory. 
         [0046]      FIGS. 7 to 10  are sections in the vertical plane including the pivot axis  264  of the combiner  220 , at different stages at the limit of travel of translation of the combiner  220 . The figures show a part of the base  258  of the combiner  220 . The base  258  is attached to the combiner  220  and can pivot with it, relative to the carriage  222 , on a substantially horizontal axis. The base  258  includes two snap-fit spindles  260  raised on either side of the base  258  on the pivot axis. Each of the spindles  260  is intended to snap into a hollow  262  formed in a respective stop  256  which limits the movement in translation of the combiner  220 . 
         [0047]    The snap-fit spindle  260  is mounted axially movably on the pivot axis. The spindle is maintained on the pivot axis  264  by a guiding socket  266  and is pushed towards the outside of the socket  266 , by a spring  268 , so as to project on the side of the base  258  of the combiner. As shown in  FIG. 8 , the stop  256  cooperating with the spindle  260  presents a ramp  270  against which the spindle  260  comes into abutment when the combiner  220  is moved from its rest position towards its display position. At the limit of travel of the combiner  220 , the spindle  260  is therefore pushed by the ramp  270  into the guiding socket  266 . At the upper end of the ramp  270  is the hollow  262 , the shape of which corresponds approximately to the negative of the shape of the spindle  260 . When the spindle  260  arrives at the height of the hollow  262 , the spring  268  pushes it into the hollow  262 , which prevents the continuation of the movement of translation of the combiner  220  and of its base  258 . It will be noted that the spindle  260  and the hollow  262  act as indexing means which define the position of the combiner  220  apart from a degree of freedom (i.e. the tilt of the combiner.) This immobilisation permits significant reduction in the vibrations of the combiner  220  and therefore of the virtual image produced in the field of view of the user. 
         [0048]    It will be recalled that the tilt of the combiner (see  FIG. 6 ) can be adjusted by adjustment of the limit of travel of the lifting carriage  222 . When the combiner  220  and its base  258  are immobilized on the axis  272  passing through the snap-fit hollows, any continuation of the movement in translation of the lifting carriage results in pivoting of the combiner  220  about the pivot axis  264  (which then coincides with the axis  272  passing through the snap-fit hollows.) Simultaneously, the spring  274  (see  FIG. 6 ) which keeps the combiner  220  upright on the carriage  222  is tensioned. 
         [0049]    When the movement of the carriage  222  is reversed, the tension of this spring  274  serves to straighten up the combiner  220 . Then, the snap-fit spindles  260  are released and the combiner  220  is moved into its retraction position while being upright on the lifting carriage  222 .