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
  • G02B3/00—Simple or compound lenses
  • G02B3/0006—Arrays
• • 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
  • 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
  • G02B2027/0118—Head-up displays characterised by optical features comprising devices for improving the contrast of the display / brillance control visibility
• • 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
  • G02B2027/0123—Head-up displays characterised by optical features comprising devices increasing the field of view
• • 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
  • G02B2027/0132—Head-up displays characterised by optical features comprising binocular systems
• • 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
  • G02B2027/015—Head-up displays characterised by mechanical features involving arrangement aiming to get less bulky devices
• • 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
  • G02B2027/0161—Head-up displays characterised by mechanical features characterised by the relative positioning of the constitutive elements

Definitions

• the present invention relates to a head-up display, also called head-up display, head-up collimator or head-up display system, compact and having a large exit pupil. More particularly, the present invention relates to such a viewfinder whose energy consumption is reduced.
• the head-up displays also known as the HUD, of the English Head-Up Display
• HUD augmented reality display systems
• Such systems can be placed in the visor of a helmet, in the cockpit of an aircraft or within the cabin of a vehicle. They are thus positioned at a small distance from the eyes of the user, for example a few centimeters or tens of centimeters.
• Figure 1 illustrates, schematically, the operation of such a device.
• a semitransparent blade 10 is placed between the eye of the user 12 and a scene to be observed 14.
• the objects of the scene to be observed are generally located at infinity or at an angle important distance from the observer.
• a projection system is planned.
• This system comprises an element for displaying an image 16, for example a screen, located at the focal point object of an optical system 18.
• the image displayed on the screen is thus infinitely collimated by the optical system 18. The user does not have to make an effort of accommodation, which limits the visual fatigue of the latter.
• the projection system is placed perpendicular to the axis between the scene and the observer so that the beam from the optical system 18 reaches the semi-transparent plate perpendicular to this axis.
• the beam from the optical system 18 thus reaches the semi-transparent plate 10 at an angle of 45 ° with respect to its surface.
• the semi-transparent plate 10 combines the image of the scene 14 and the image resulting from the projection system 16-18, from which
• the observer 12 displays an image comprising the projected image superimposed on the image of the scene 14.
• the observer's eye In order to visualize the image projected by the projection system 16-18, the observer's eye must be placed in the reflection zone of the beam coming from the optical system 18 on the plate 10.
• An important constraint to be respected is to hold account possible movements of the head of the user in front of the projector, and therefore to provide a beam output of the optical system 18 as wide as possible. In other words, it is necessary to provide an optical system 18 whose output pupil is large, for example between a few centimeters and a few tens of centimeters, so that the head movements of the observer do not imply a loss of light. projected information.
• Another constraint of head-up systems is to provide a relatively compact device. Indeed, significant space constraints weigh on these devices ⁇ sitifs, especially when used in aircraft cockpits or car interiors of limited volume. To limit the size of head-up systems, it is necessary to provide devices whose focal length is reduced.
• An object of an embodiment of the present invention is to provide a compact head-up viewfinder having a large exit pupil.
• An object of an embodiment of the present invention is to provide such a device whose power consumption is reduced.
• an embodiment of the present invention provides a head-up viewfinder, including subscreens whose positions and dimensions are defined according to the length of the optical path and a maximum allowed movement length in a perpendicular plane. to the optical axis and located at a distance equal to the optical path length so that the information projected by all subscreens is viewed over the entire authorized movement length, characterized in that the subscreens have an increasing light intensity as a function of their distance from the main optical axis of the viewfinder.
• the positions and the dimensions of the subscreens are further defined according to the average deviation between the two eyes of a person.
• each sub-screen is associated with an optical subsystem, the subscreens being placed in the object focal plane of the optical subsystems.
• the optical subsystems are regularly distributed in a plane perpendicular to the main optical axis of the viewfinder.
• the projected information is an image that is distributed over all subscreens.
• the sub-screens are defined on the surface of a substrate.
• the subscreens are disjoint.
• the maximum allowed movement length is zero and the view of the observer is monocular, the subscreens being placed symmetrically on either side of the axis.
• main lens of the viewfinder each subscreen having a length along the first axis equal to fL / D, the subscreens being spaced edge to edge by a distance equal to L, f and L being, respectively, the focal length and the width of the optical subsystems, where D is the length of the optical path.
• the maximum permitted movement length is non-zero
• the observer's vision is monocular device and the device comprises a number Q of optical sub-system and sub-projectors, the subscreens being placed symmetrically on either side of the main optical axis of the viewfinder, the centers of the subscreens being placed at a distance from each other equal to fL / D + L, each sub-screen having a length along the first axis equal to f / D (L + B), within the limit of an area of a dimension equal to QfL / D centered on the optical axis of the associated optical subsystem, f and L being, respectively, the focal length and the width of the optical subsystems, where D is the length of the optical path.
• the maximum allowed movement length is zero and the view of the observer is binocular, the subscreens being placed symmetrically on either side of the axis.
• main viewfinder lens each subscreen having a length along the first axis equal to fL / D, except the sub-screens furthest from the main optical axis having a length equal to f / D (L + y / 2), the subscreens being spaced edge to edge by a distance equal to L, f and L being, respectively, the focal length and the width of the optical subsystems, where D is the length of the optical path.
• the maximum allowed movement length is equal to an average difference between the two eyes of a person and the view of the observer is binocular
• the subscreens being placed symmetrically on either side of the main optical axis of the viewfinder, each sub-screen having a length along the first axis equal to fL / D, the subscreens being distant edge-to-edge by a distance equal to L where f and L are, respectively, the focal distance and the width of the optical subsystems, where D is the length of the optical path.
• the maximum movement length allowed is greater than an average difference between the two eyes of a person
• the view of the observer is binocular and the device comprises a number Q of optical sub-systems and sub-projectors, the sub-screens being placed symmetrically of on both sides of the main optical axis of the viewfinder, the centers of the sub-screens being placed at a distance from each other equal to fL / D + L, each sub-screen having a length along the first axis equal to f / D (L + By), within the limit of an area of a dimension equal to QfL / D centered on the optical axis of the associated optical subsystem, f and L being, respectively, the focal distance and the width of the optical subsystems, where D is the optical path length.
• the viewfinder comprises an odd number of sub-screens along the first axis, the intensity of illumination of the sub-screen of rank i being equal to the intensity of illumination of the sub-screen.
• central screen (i 1) multiplied by the following factor:
• f and L being, respectively, the focal length and the width of the optical subsystems, where D is the optical path length.
• the viewfinder comprises an even number of sub-screens along the first axis, the intensity of illumination of the sub-screen of rank i being equal to the intensity of illumination of the sub-screen.
• central screen (i 1) multiplied by the following factor:
• D 2f D 2f f and L being, respectively, the focal length and the width of the optical subsystems, where D is the length of the optical path.
• each sub-screen consists of a matrix of organic light-emitting diode cells.
• Figure 1 previously described, illustrates the principle of operation of a head-up display
• Figure 2 illustrates the principle of operation of a head-up display according to an embodiment of the present invention
• FIGS 3 to 5 illustrate different observations made using the devices of Figures 1 and 2;
• Figures 6 to 8 illustrate optical structures for determining geometric rules for designing a screen of an improved head-up display
• FIGS 9 and 10 illustrate the subscreen distribution according to one embodiment of the present invention.
• FIGS. 11 and 12 illustrate rules for the formation of head-up display sub-projectors according to one embodiment of the present invention.
• a compact head-up viewfinder that is to say comprising a projection system having a space of less than a few tens of centimeters and having a large exit pupil
• elementary projection systems each projection subsystem operating in the same way and projecting a portion of an image to be superimposed on a real image.
• Figure 2 schematically shows a head-up viewfinder according to one embodiment.
• the device comprises a semitransparent plate 10 which is placed between the observer 12 and a scene to be observed 14.
• the surface of the semi-transparent plate 10 forms an angle, for example of 45.degree. axis between the scene and the observer, and does not disturb the arrival of rays from the scene to the observer.
• the semitransparent plate can be replaced by an interference filter performing the same function as a semi-transparent plate.
• a projection system of an image to be superimposed on the image of the scene is planned. It comprises an image source 24, for example a screen, associated with an optical system 26.
• the projection system is placed here perpendicularly to the axis between the scene and the observer, and the beam that comes from the optical system 26 reached the semi-transparent plate perpendicular to this axis.
• the semi-transparent plate 10 combines, i.e. superimposes, the image of the scene 14 and the projected image from the optical system 26, whereby the observer views the superimposed projected image to the real image of the scene 14.
• the system of Figure 2 operates in the same way as the system of Figure 1.
• the optical system 26 comprises a set of optical subsystems 26A, 26B and 26C of the same focal length.
• the image source 24 is placed at a distance from the optical system 26 equal to the object focal distance of each of the optical subsystems 26A to 26C.
• three sub-screens 24A, 24B and 24C are shown. Note that this number may be more or less important.
• Each sub-screen 24A, 24B and 24C is associated with an optical subsystem 26A, 26B, 26C. Contrary to what is shown, the subscreens can be shifted from the optical axes of the associated optical subsystems, as will be seen below.
• the projection system therefore comprises a plurality of sub-projectors.
• each optical subsystem has an opening, called elemental, "moderate".
• the elementary aperture of an optical subsystem is defined as the ratio of its own focal distance to the size of its own exit pupil.
• the parallel association of the sub-projectors thus makes it possible to obtain an optical system whose opening is particularly weak insofar as, for the same distance between screen and projection optics, a large total exit pupil is obtained. , equal to the sum of the exit pupils of each optical subsystem.
• the optical system thus has a small opening while being formed of simple elementary optical structures. The compactness of the complete device is thus ensured.
• the screen 24 is provided so that each sub-screen 24A, 24B, 24C displays part of the information, the complete information being recombined by the brain of the observer. For this, the image that one wishes to project in augmented reality is divided into blocks which are distributed on the various subscreens.
• the screen 24 may be comprised of a cell array comprising organic light emitting diodes ⁇ (English OLED, Organic Light-Emitting Diode) or a matrix of LCD sub-screens or picture .
• organic light emitting diodes ⁇ English OLED, Organic Light-Emitting Diode
• LCD sub-screens or picture a matrix of LCD sub-screens or picture .
• one or more layers of organic materials are formed between two conductive electrodes, the assembly extending on a substrate.
• the upper electrode is transparent or semi-transparent and is usually made of a thin layer of silver whose thickness may be of the order of a few nanometers. When a suitable voltage is applied between the two electrodes, a phenomenon of electroluminescence appears in the organic layer.
• FIG. 3 is illustrated an image 30 which is displayed on a screen such as the screen 16 of FIG. 1 (thus with a single-shot optic).
• a frame 32 which surrounds the image 30, schematically represents the exit pupil of the projection device 18 of FIG. 1.
• the exit pupil 32 is slightly wider than the displayed image. by the screen 30.
• the observer observes all the information contained in the image 30, as long as the observer's head remains in what is called the "eye box" the device (in English eye-box or head motion box).
• This "eye box” is defined as the space where the observer can move his head while receiving all the projected information. In other words, as long as the observer's head remains in the eye box, he receives all the projected information.
• FIG. 4 illustrates the view of the information by an observer, in the case where the head-up viewfinder comprises a single-pupillary optics (case of FIG. 1), when the head of the observer leaves the eye box. .
• the exit pupil 34 portion seen by the observer
• the image 30 which implies that only a portion 30 'of the image 30 is seen by the observer.
• Figure 5 is illustrated the vision of the information by an observer, in the case where the head-up viewfinder has a multi-pupil optical (Figure 2), when the head of the observer out of the eye box.
• the exit pupil 36 seen by the observer is shifted with respect to the image 30, which implies that only a portion 30 "of the image 30 is accessible to the observer.
• the portion 30 is viewed in a fragmented manner.
• each sub-projector has its own eye box.
• the observer when the observer leaves the overall eye box of the device, it also leaves the eye box of each of the sub-projectors, which causes a fragmentation of the image seen by the observer.
• the final image seen by the observer consists of a set of vertical bands 30 "(in the case of a lateral displacement of the observer's head) of portions of the image 30.
• the positioning and the size of the sub-screens of a head-up viewfinder with multi-pupil optics must be adapted according to a predefined desired eye box.
• a predefined desired eye box Various cases will be described below, starting from an eye box of zero size (only one position of the observer ensures the reception of all the information), the projected image filling the whole of the surface of the exit pupil.
• Figures 6 to 8 illustrate optical structures for determining geometric rules for enhanced placement of OLED subscreens.
• optical subsystems 26] _ and 262 extend symmetrically on either side of the principal optical axis of the device.
• the goal is to determine the area of each subscreen useful when the observer closes an eye
• optical path (monocular vision), that is to say the portion of each sub-screen seen by the eye, if the eye is placed on the main optical axis of the device at a distance D from the optical system 26.
• the distance D between the optical subsystems 26 ] _ and 262 and the observer is called optical path.
• the optical path and thus the distance D that we will consider later, corresponds to the light path between the optical subsystems 26] _ and 262 and the observer, for example through the semi-reflective blade 10.
• a device comprising three sub-projectors consisting of three sub-screens 24 ' ] _, 24 * 2 and 24 * 3 formed on a substrate 40 facing three optical subsystems 26' ] , 26 * 2 and 26 * 3.
• the substrate 40 is placed in the object focal plane of the optical subsystems 26 '], 26 * 2 and 26 * 3.
• the central sub-projector (24 '2, 26 * 2) has its optical axis coincident with the main optical axis of the device and the peripheral sub-projectors extend symmetrically with respect to the main optical axis of the device.
• the portion 42 'of a peripheral sub-screen accessible in monocular vision by an eye placed on the main optical axis of the device, at a distance D from the optical system 26.
• the surface of this sub-screen visible by an eye (monocular vision) placed on the main optical axis of the device is equal to fL / D.
• FIG. 8 shows the case of FIG. 6 with a projector comprising two sub-projectors each consisting of a sub-screen 24], 242 and an optical subsystem 26]. to the subscreen region which is accessible to an observer in binocular vision.
• the two eyes of the observer R and L are placed on either side of the main optical axis of the device, at a distance y / 2 of this main optical axis (y being thus the gap between the two eyes of the observer).
• the right eye R respectively the left eye L
• the useful surface of the sub-screen 24 that is to say the surface of the screen 24 which is seen at least by one eye of the user, has a width equal to fL / D + fy / 2D.
• the head of the observer In order to define the useful area of each of the subscreens in operation, it must be taken into account that the head of the observer is likely to move, according to a maximum amplitude that is predefined. Note that, vertically, the head of an observer is less subject to movement and vision is monocular. However, The following teachings apply to both vertical head movement and lateral movement.
• the maximum accepted movement length of the head (equal to the size of the eye box along a first axis, for example horizontal) will be called B.
• B thus corresponds to the maximum peak-to-peak amplitude in motion of the accepted head.
• Subscreen positioning rules are defined below so that if the observer's head moves in a direction a distance less than or equal to B / 2, or in an opposite direction of a distance less than or equal to B / 2, the view of the information given by all the subscreens is always complete, ie each pixel of each subscreen is seen at least by one both eyes of the observer when describing the entire eye box.
• the sizing and positioning rules of each of the subscreens vary according to whether it is desired to have an amplitude in motion that is zero or not authorized, and that one places oneself in binocular or monocular vision. (eg binocular vision horizontally, monocular vertically).
• the inventor has shown that the reasoning leading to the sizing of the sub-screens in a direction in which the vision is monocular with a non-zero eye box also applies to the case where the vision is binocular with an eye box B is greater than the distance between the two eyes y of the observer.
• Figures 9 and 10 illustrate rules for positioning and sizing sub-screens on a substrate according to one embodiment.
• the sub-screens 24] _ 245 are placed in the object focal plane of the optical subsystems 26] _ 265 so that, in monocular vision, the reconstituted image fill all the exit pupil.
• the eye box has a dimension B zero (the slightest movement of the head of the observer implies a loss of information).
• a simple calculation makes it possible to obtain that the subscreens have a length in the plane of the figures equal to fL / D and are separated by a distance equal to the size of the optical subsystems L.
• the sub-screens are more or less offset from the optical axis of the associated optical subsystem, as a function of their distance from the main optical axis of the projection system.
• regions 50j to 5 ⁇ 5 which are placed in the object focal plane of the optical subsystems 26j to 265 and which are centered on the optical axis of the optical subsystems 26 ] _ to 265.
• Each region 50j_ to 5 ⁇ 5 has a length equal to QfL / D, in this case 5fL / D.
• each sub-screen 24 ] _ to 245 is placed opposite a portion of the region 50j_ to 5 ⁇ 5 corresponding to its rank, that is to say that the subscreens at the ends of the device are placed at the ends of the regions 50j_ to 5 ⁇ 5 on both sides of the device.
• the illustration of the regions 50j_ to 5 ⁇ 5 makes it possible to represent the part of the image that the corresponding sub-screen must display: the sub-screens at the periphery thus display a peripheral portion of the image.
• an eye box is desired to obtain, always by monocular vision at a distance D of the projection device, a dimension equal to B] _ relatively low.
• the solid lines delimit the zone of the visible focal plane when the eye moves to the left in the figure (by a distance B ] _ / 2) and the dashed lines delimit the zone of the visible focal plane when the 'eye moves right in the figure (from a distance B ] _ / 2).
• an eye box still in monocular vision at a distance D from the projection device, a dimension equal to B2 relatively large.
• the solid line delimits the limit of the visible focal plane when the eye moves to the left in the figure (by a distance B2 / 2) and the dashed line delimits the limit of the visible focal plane when the eye moves to the right in the figure (from a distance B2 / 2).
• each sub-screen has a dimension greater than fL / D.
• the image to be superimposed on the real image is in these two cases distributed over portions of each of the subscreens of dimensions equal to fL / D.
• the information displayed on the rest of the subscreens is redundant with the neighboring subscreens, which ensures the dimensions of the desired eye boxes.
• Figures 9 and 10 provide the following sizing and positioning rules. It is chosen to form a matrix of QxQ 'sub-projectors, Q and Q' which can be odd or even. In both directions of the projector, the sub-projectors are arranged symmetrically with respect to the main optical axis of the projector.
• the sub-screens are placed symmetrically with respect to the main optical axis of the device, have dimensions equal to fL / D and are spaced edge-to-edge by a distance L (the centers of the subscreens are thus distant by a distance equal to L + fL / D).
• the subscreens have dimensions equal to f / D (L + B).
• the edge to edge of the subscreens is then less than L.
• the magnification of the subscreens is made so as not to leave an area of a dimension equal to QfL / D centered on the optical axis of the subset. the associated optical system, where Q is the number of sub-projectors in the direction considered.
• the peripheral sub-screens have a dimension equal to (L + y / 2) f / D, where y is the difference between the two eyes of a person. Note that in the literature, the average difference mQ there are between the two eyes of a person is between
• all subscreens have dimensions equal to fL / D and are spaced edge to edge of a distance L.
• the centers of the sub-screens are thus separated by a distance equal to L + fL / D.
• the subscreens are centered in the same way as above (the centers of the subscreens are placed at a distance from each other). the others are equal to fL / D + L but are larger by (By) f / 2D on both sides, so the subscreens have a dimension equal to (L + By) f / D. subscreens is therefore smaller than L.
• the subscreen magnification occurs so as not to exceed an area of QfL / D dimension centered on the optical axis of the associated optical subsystem, where Q is the number of sub-projectors along the axis of movement considered.
• the formation of screens consisting of sub-screens whose dimensions and positioning are defined in the above manner reduces the consumption of the device, since only useful portions of a screen, or only small screens, are powered.
• the subdivisions of the subscreens proposed above can correspond directly to the practical realization of upper electrodes of OLED screens, which can be powered by conductive tracks (not shown) of sizes adapted to the transmission of a power supply current of high amperage.
• each sub-screen 24-j ', 24'-j_ sees its optical subsystem 26j_, 26'_ associated at an angle more and more. closed.
• the composition of the image, viewed by the observer is made with a gradient of luminance which decreases from the center to the edge of the image.
• many screens, including OLED-based screens are not Lambertian light sources that ensure, regardless of the observation point of the screen, the reception of the same luminance. It is therefore necessary to take this phenomenon into account.
• FIG 11 illustrates a subscreen 24'-j which is decentered with respect to the main optical axis of the device (represented in dotted lines), associated with an optical subsystem 26 1 of dimension equal to L and of focal length f (the sub-screen is located at a distance f from the optical subsystem).
• the device comprises an odd number of sub-projectors.
• D being the length of the optical path to the observer, the angle ' j _ is defined by:
• the flux passing through the lens 26 varies proportion 1 ⁇ tionally to the value 2n (1-cos ( 'j_ / 2)).
• FIG. 12 is a curve of the ratio r'-j as a function of the rank i of the optical subsystem in the device, on either side of the main optical axis of the device.
• the intensity of illumination of this sub-screen must be at least 1.5 times the intensity of illumination of the central sub-screen. It will be noted that, for a device comprising an even number of sub-projectors along an axis considered, the ratio r-j is then defined with respect to the optical subsystem of rank 1 by:
• ⁇ 3 ⁇ 4_ arctanl + arctan

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