FR2594563A1 - Compact and retractible head-up collimated-display device - Google Patents

Abstract

The device enables the instantaneous elevation field of view to be increased using a mounting having two parallel mirrors and producing a minimum masking effect. The two mirrors 4, 5 are placed inside the casing 1 in order to produce the increase in the elevation pupil and a single mirror 6, placed outside the casing, constitutes the optical combining system. A mechanism 8 for retracting the combining mirror, which is positioned 6 above the casing beyond the field of view of the external background, is also added with the purpose of reducing the masking effect during the periods when the collimator is not being used. The invention applies to aeronautics in order to form a head-up sight, preferably for using in a low position.

Description

COLLIMATE HIGH HEAD VISUALIZATION DEVICE,
COMPACT AND RETRACTABLE
The present invention relates to a collimated head-up display device, compact and retractable. These devices, generally used on board aircraft, make it possible to observe a collimated synthetic image superimposed on the natural vision of the landscape seen through the ice of the cokpit. They are often referred to as head-up viewfinders, or HUD (short for Head-tJp
Display).

 These sighting devices include an optical combination of images to transmit towards the observer the radiation coming from the landscape and to reflect towards the observer the radiation corresponding to a synthetic image to be displayed. This is produced by an optical collimator assembly comprising an optical objective and luminous objects representing the image of the symbols to be displayed and which are positioned in the focal plane of the objective. To do this, the light object generating means often use a cathode ray tube, providing a high definition of the symbols on the screen, this image then being sent back to infinity by the objective.

 The invention advantageously applies to a head-up viewfinder mounted in the low position, that is to say in which the combination optics is disposed towards the bottom of the windshield, but can also be applied to a mounting in the high position or the combination optics is arranged towards the top of the windshield.

 It is essential that the pilot sees all of the luminous objects projected without annoying movements of the head and without having to get too close to the semi-transparent glass of the collimating device through which the observation is made.

 The image of the edge of the lens in the glass acts like an optical pupil. The useful field of the device is constituted, in monocular vision, by a cone centered on the eye and resting on the optical pupil and, in binocular vision, by a set of two cones centered respectively on the eyes of the observer and s '' each pressing the optical pupil. The vision of the markers according to a viewing direction considered, remains ensured for displacements of each eye included in an area corresponding to that of the optical pupil.

 It is important to obtain a large optical pupil to increase the comfort of the pilot by ensuring him an easy vision at a distance sufficiently far from the semitransparent glass.

 In practice, the increase in the dimensions of the optical pupil is generally carried out to the detriment of the dimensions and the compactness of the device. The latter in head-up mounting must have a dimension as small as possible, in particular according to the direction of the height, so as to facilitate its installation and to not cause any discomfort for the vision and the movements of the pilot.

For collimator devices having good optical qualities and in particular, operation free from distortions or parallax, the minimum possible height of the housing is substantially imposed by the diameter of the objective.

 I1 is known to increase in elevation the optical pupil of the device and consecutively the instantaneous field of vision of the observer without modifying the diameter of the optical objective, using a second plane glass arranged parallel to the first ice.

A solution of this kind described in French Patent No. 2 389 911 uses a second semi-transparent lens arranged at a distance further from the optical objective to produce an additional pupil and obtain a resultant pupil enlarged towards the high sites relative to the initial optical pupil. The semi-transparent treatment on the first ice is limited above.

 In these materials, the electronic module generating light objects and the collimating optics are maintained in a housing to which the optics for combining images are also mechanically attached. The latter as well as the mechanical uprights which support it present a mask which can be significant. We are well aware that this mask effect is very annoying for operation if it is located in the field of vision of the observer through the windshield. This mask effect is further increased in versions with two windows of the aforementioned type. In addition, in head-up versions mounted in the high position and in particular used on helicopters, it is also necessary to consider the mask effect produced by the housing.

 The object of the invention is to produce a head-up viewfinder which satisfies both instantaneous vision criteria in a wide field in elevation and a minimal mask effect of the combination optics situated outside the housing, so remedy the aforementioned faults and limitations.

 According to the invention, this object is achieved by having an assembly of two parallel flat windows inside the housing to produce the effect of increasing pupil in elevation, by having only one flat window outside the housing and which is the combination optic. I1 results in a higher compactness of the optical part outside the housing and increased optical quality, the perception of the external landscape being effected only through a single lens; The mask effect is reduced, in particular by the use of smaller amounts.

 In addition, to increase the pilot's comfort, provision is made to retract the combination lens when the collimator is not in use, bringing it to a rest position outside the field of observation of the outside landscape through the windshield. broken.

 According to the invention, it is proposed to produce a head-up viewfinder comprising an optical collimating objective and a semi-transparent combination lens to visualize infinite light data and observe them superimposed on the landscape, electronic means generating light data. to visualize, a box fixed to the carrier vehicle and containing the electronic generating means and the collimation optics, and a mounting of two parallel flat mirrors to enlarge the optical pupil in elevation and correlatively the instantaneous field of vision of the data. is placed entirely inside the housing downstream of the collimating objective and is composed of a first semi-transparent mirror followed by a second reflecting mirror, the combination glass located outside the housing ensuring reflection towards the observer of collimated data in the enlarged pupil produced by the assembly.

 The features and advantages of the present invention will appear in the following description given by way of example, using the appended figures which represent: - Fig.l, a general diagram of a display device according to the invention - Fig.2, an embodiment showing the housing and the arrangement of the image generator and associated optics; - Fig.3 and Fig.4, the same embodiment showing for elevation the entire device before the combination glass respectively in the operating position and in the retracted position; - Fiv.5, an exemplary embodiment of the mechanism for retracting the combination glass in the operating position of the collimator; - Fig.6, the same retraction mechanism in the rest position corresponding to a non-operation of the collimator; ; - Fig.7, an example of an installation for protecting the combination glass in the retracted position, for a head-up display device mounted in the low position.

 Referring to Figure 1, there are the essential elements of the collimator according to the invention, comprising, in a housing 1: an image generator 2, for example of the cathode ray tube type; a collimator optic 3 for projecting the image located in the focal plane to infinity; a partially transparent mirror 4 and a reflecting mirror 5. Part of the radiation from optics 3 is reflected by the mirror 4 and another part by the mirror 5, these two elements being arranged in parallel and successively on the axis Z of the optics 3. They are inclined on the optical axis Z to return the radiation to the combination lens 6 located outside the housing 1. The lens 6 has an inclination which can be of the same order as that of the elements 4 and S, or different; the inclination value will generally be determined to make the normal direction of sight Z1 of the observer coincide with the center of the instantaneous field of vision 83 of the collimated image in the enlarged pupil. A crossing glass 7 allows the passage of radiation while preserving the tightness of the housing 1. The glass 6 is partially transparent or of holographic type, to ensure the reflection of the radiation coming from the image generator 2 and the transmission of the radiation coming of the external landscape, and allow simultaneous observation for an observer in O.

 In addition, a retracting mechanism 8 allows the window 6 to be folded down into the rest position referenced 6R when it is not desired to use the collimating device and in order to free the visual field of the window 6 and its mechanical coupling uprights. to the housing. The retraction mechanism 8 makes it possible to position the glass 6R parallel to the crossing glass 7.

 The assembly of the two mirrors 4 and 5 acts like a double ice system mentioned previously and having the aim of increasing the instantaneous field of observation in site of the collimated image. This increase has been represented by the pupils P1 and P2 respectively resulting in the image of the pupil of the objective 3 seen through the combination glass 6 after reflection on the mirror 4 on the one hand and on the mirror 5 of somewhere else. The production of mirrors 4 and 5 in particular from the dimensional point of view and the extent of the reflective treatments is a function in particular of the shape desired for the enlarged pupil, of the position of the observation point O, of the total field to be produced. The advantage provided in the proposed solution is that the two optics 4 and 5 are out of the visual field of observation since they are located in the housing 1. They therefore present no discomfort to the observer. Considering an increase of the pupil towards the high sites it is the mirror 5 which produces it in this assembly.

 The semi-transparent glass 6 outside the housing 1 reflects the radiation returned by the elements 4 and 5 and corresponding to the enlarged pupil, towards the observer; moreover, this ice conventionally transmits radiation from the landscape. As can be seen, the glass 6 is not necessarily parallel to the mirrors 4 and 5. The combination optics reduced to a single glass 6 placed in the enlarged field produces a minimal mask effect.

 In addition, provision is made to protect the combination glass 6 in the rest position 6R using a curtain, an example of which will be given later in FIG. 7. This protection makes it possible to avoid damaging the glass and suppress parasitic reflections, in particular solar, which could annoy the pilot. In the rest position, the glass stored on the top of the collimator box creates a minimum mask on low plane visibility, given these shapes.

 Figures 2 to 4 show an exemplary embodiment. In Figure 2 there is shown the housing 1 in top view with the crossing glass 7. The housing is partially open to show inside the arrangement of the image generator 2 of the cathode ray tube type and the collimator optics associated comprising a first group of lenses 3A and a second group of lenses 35 with, between the two groups, a reflecting reflecting mirror 11. This arrangement makes it possible to save on the overall dimensions of the housing by making it possible to return the tube Z laterally .

 Figure 3 shows the general arrangement of Figure 1 in the operating position, the glass 6 being raised, there is also shown the glass 12 of the porthole of the cockpit. For the sake of simplification, the mechanisms for coupling the glass 6 to the housing or the retracting device 8 have not been shown.

 In FIG. 4, the same elements are shown in the rest position, during the periods of non-operation of the collimator device. The glass 6R in the retracted position is stored on the top of the housing above the crossing glass 7 creating a minimum mask, or even zero, for the low visibility of the landscape through the porthole 12.

 An exemplary embodiment of the retraction device is shown in Figure 5 in the operating position and in Figure 6 in the rest position. This device for retracting the ice 6 makes it possible to free the field of vision of the exterior landscape as much as possible by the pilot during the flight phases not using the collimator. The required precision requires reproducibility of the positioning of the partially transparent glass 6 in the use position.

This is ensured by a mechanical stop system 29. The displacement of the glass 6 between its normal position of use as a combination element, and that of storage indicated 6R is done by means of a mechanical assembly which can consist as shown in a rod 22 and two elements 21 and 23 provided with slides to be able to slide one into the other. This mechanical assembly makes it possible to bring the glass 6 into its position 6R by a translational movement of the element 23 relative to the element 21 in the direction A along a slide while simultaneously providing a rotation of angle o (of element 21 around an axis of rotation 24. Direction A corresponds to the longitudinal direction of element 21 passing through the center of rotation 24 of this element. During this movement the link 22 has - even rotated at an angle 8 around its axis 25. The support part 23 which slides in 21 is connected to the link 22 via a rotation axis 26. The assembly is controlled manually by the pilot.

 FIG. 6 represents the retracting device after execution of its respective movements and positioning of the glass in its rest position 6R.

 Figure 7 shows an exemplary embodiment of the ice protection means 6 in the retracted position 6R. To avoid scratching it and also to prevent parasitic reflections from external sources, in particular from the sun, towards the observer. This assembly consists of an opaque curtain 31 which can be pulled manually by a tongue 32 to cover the glass 6R. The lateral parts of the curtain and the end upright 33 slide by the lateral edges in slides 35. The shape of the end strip 33 can be made for example so as to be able to snap into a corresponding notch 36 in each of the slides for be kept at the end of travel in the locking position. The curtain by its other end is made integral with a mechanical axis 37 which can rotate by means of rolling bearings 38. The rolling bearings are secured by their outer ring of the housing 1. A return spring 40 makes it possible to bring back the curtain which wraps around Paxe 37 to release the glass 6R and restore it to its operating position 6.

 The description above admits of numerous variants conforming to the exposed characteristics of the invention. In particular, the cathode ray tube can be replaced by another light source such as a screen with liquid crystals, with light-emitting diodes, with plasma, etc. The lens 6 advantageously comprises a hologram to improve the contrast and the transparency of the landscape and for increase the reflection rate of collimated imagery and in doing so considerably increase the energy efficiency of the combination optics.

Claims (10)

 1. Head-up collimated display device, comprising an optical collimating objective and a semi-transparent combination lens for infinitely viewing light data and observing them superimposed on the landscape, electronic means generating light data to be displayed , a box fixed to the carrier vehicle and containing the electronic generating means and the collimation optics, and an assembly of two parallel flat mirrors to enlarge the optical pupil in elevation and correlatively the instantaneous field of vision of the data, the device being characterized by the fact that said assembly is disposed entirely inside the housing (1) downstream of the collimating objective (3) and is composed of a first semi-transparent mirror (4) followed by a second mirror (5 ) reflecting, the combination glass located outside the housing ensuring the reflection towards the observer of the collimated data in the enlarged pupil produced by ledi t mounting.  2. Device according to claim 1, characterized in that it further comprises a mechanical retracting device (8) of the combination glass allowing it to be brought back into a rest position (6R) lying outside the field of observation desired for the vision of the external landscape.  3. Device according to claim 2, characterized in that the rest position (6R) corresponds to a positioning of the combination glass (6) substantially parallel to a crossing glass (7) which is provided with the housing (1) for allow the radiation corresponding to said collimated data to pass into the enlarged pupil.  4. Device according to claim 2 or 3, characterized in that the mechanical retraction device comprises a link (22) and two elements (21, 23) sliding one inside the other along slides, one of these elements (21) supporting the combination glass (6).  5. Device according to any one of claims 2 to 4, characterized in that it further comprises a means for protecting the combination glass (6), this protection means (31) covering the glass (6 ) in the rest position (6R) and preventing stray reflections.  6. Device according to claim S, characterized in that said protection means is constituted by a curtain (31) opaque for ambient radiation and which is placed above the combination glass in the rest position (6R).  7. Device according to any one of claims 1 to 6, characterized in that in the housing (1) is included, downstream of the collimating optics (3), said first plane mirror (4) semitransparent then said second reflecting plane mirror (5), these two mirrors being arranged in parallel and inclined on the optical axis (Z! of the collimating optics (3) to return the collimated radiation outside the housing towards the combination glass (6 ), the crossing of the housing being effected through a crossing glass (7).  8. Device according to claim 7, characterized in that the electronic means generating light data (2) comprise a cathode ray tube (2) and that the collimation optics (3) consists of two groups of lenses (3A and 3B ) and a reflecting mirror (11) to allow a lateral arrangement of the tube.  9. Device according to any one of claims 1 to 8, characterized in that the combination lens (6) is produced with a hologram adapted to optimize the rate of reflection of the radiation of the collimated image and that of transmission of the radiation exterior from the landscape.  10. Device according to any one of claims 1 to 9, characterized in that the housing (1) is located below the combination glass (6) for use in the low position.