FR2670438A1 - Windscreen for a collimating driving system - Google Patents

Abstract

A windscreen (130) for a collimating driving system is formed such that its opposing large external surfaces (138 and 140) are not parallel. As a consequence, an image coming from a display source (14), and reflected by a large external surface (138) of the windscreen is superimposed on the image reflected by the opposite large external surface (140) of the windscreen (130).

Description

 The present invention relates to a combiner for a driving collimator system and, in particular, an automobile windshield fulfilling the function of a combiner for a steering collimator system and having a wedge-shaped configuration to eliminate the formation of images. doubles.

 A driving collimator system is a display device that displays information for an observer while the observer simultaneously views the real world around and through the display.

Piloting control systems are often incorporated into aircraft cockpits so that the pilot can monitor flight information. More recently, these systems have been used in land vehicles such as cars, trucks or the like. The display is generally positioned so that by examining the vehicle operating information, the observer does not have to look down at the vehicle dashboard and look away from the vehicle. field of vision at the front of the vehicle, as is normal for a driver.

 A collimator control system generally comprises a display projection system, a collimator and a combiner. The projection system includes a light source that projects the service information through the collimator, which generally aligns the projected light rays.

The collimated light is then reflected from the combiner, which is in the driver's field of view. In this way, important information about the vehicle, such as fuel and vehicle speed information, is displayed in the driver's field of vision through the windshield and allows the driver to maintain safely his gaze on the real world, while at the same time seeing the information displayed. The reflected images of the display can be focused at a point somewhere between the immediate front of the vehicle and the optical infinity.

 Laminated or laminated windshields were used as a combiner in a driving collimator system to reflect a display image, as taught in U.S. Patent No. 2,264,044 (Lee). However, it has been observed that a secondary image is reflected by the outer surface of the windshield. This secondary image is superimposed on the first image, but offset from it, and it reduces the overall clarity of the image.

 It would be advantageous to have, for a driving collimator, a windshield that plays the rake of the combiner and gives a clear display image, without the need to incorporate additional components on or in the windshield.

 U.S. Patent No. 1,871,877 (Buckman) discloses a display system comprising a glass sheet which is mounted on the windshield or on the dashboard and which reflects instrument information to the driver.

 U.S. Patent No. 2,264,044 (Lee) discloses a motor vehicle in which an illuminated tachometer display is reflected by the interior surface of the vehicle windshield.

 US Patent No. 2,641,152 (Mihalakis) discloses a vehicle projection device, in which instrument information is reflected by a reflective screen on the inner surface of the vehicle windshield. The reflective surface is frosted and can be metal, glass or plastic.

 U.S. Patent No. 2,750,833 (Gross) discloses an optical display system capable of eliminating duplicate images that are produced in reflector-type viewfinders as used in sighting systems for the guns of an aircraft. A collimated light beam is polarized and separated into two spokes. Then one of the two spoke branches is eliminated.

 U.S. Patent No. 3,276,813 (Shaw, Jr.) discloses a motor vehicle display system that uses a highly reflective coating on the interior surface of the vehicle windshield to reflect instrument information to the driver. .

 U.S. Patent No. 3,446,916 (Abel) discloses an image combiner using a portion of the ice of an aircraft, wherein the portion of the inner surface of the ice is coated with a partially reflective film.

 U.S. Patent Nos. 3,554,722, 3,591,261, and 3,647,285 (Harvey et al.) Disclose a double-glazed window structure that eliminates the troublesome fringe patterns produced in this structure when thick float glass is used. The window structure comprises a pair of spaced apart sheets of float glass, one or the other of which has a decreasing section between a thick edge and a thin opposing edge. have a decreasing section, they are arranged in such a way that a thick edge of one of the glass sheets is placed above a thin edge of the opposite glass sheet.

 U.S. Patent No. 3,899,241 (Nalobycky, Jr. et al.) Discloses a windshield for use in an aircraft and comprising a transparent reflective coating on the inner surface in the central portion of the field of view towards the aircraft. before, so as to form a vision image receiving area Information about the vehicle is reflected by the reflective coating towards the driver of the vehicle.

 U.S. Patent Nos. 3,940,204 (Withrington) and 4,218,111 (Withrington et al.) Disclose an optical display system using holographic lenses.

 U.S. Patent No. 4,261,635 (Freeman) discloses a driving collimator system comprising a holographic combiner disposed within the vehicle windshield The hologram is in a substantially orthogonal position, midway along the an axis between the position of the observer's eye and the projection optics, so as to deflect the light from an image produced by the projection optics towards the observer's eye with a minimum of field aberration.

 U.S. Patent No. 4,398,799 (Swift) discloses a driving collimator system which simultaneously records the view of the exterior scene by the pilot and the projected display, reflecting the exterior scene and the superimposed display from a mirror mounted on the pilot's helmet and recording the reflected view with a camera mounted on the pilot's helmet.

 U.S. Patent No. 4,613,200 (Hartman) discloses a driving collimator system that uses two parallel holographic optical elements to reflect instrument information to the vehicle driver.One of the elements is part of the vehicle windshield. or is attached to it.

 U.S. Patent No. 4,711,544 (Iino et al.) Discloses a display system for a vehicle, in which instrument information is reflected by the front window of the vehicle so that the image display can be trained in a desired position, in alignment with the driver's line of sight without obstructing the driver's vision forward.

 The present invention provides, for a collimator steering system, a windshield that reduces the amount of double image formation that occurs when a laminated windshield is used as a combiner in the display system. The windshield acts as a combiner for the collimator control system without the need for additional elements or components to be incorporated on or in the windshield assembly. The windshield according to the present invention is realized in such a way that its opposite large outer surfaces are non-parallel and oriented relative to one another so that an image projected by a display source and reflected by a first large surface of the windshield is almost superimposed on the same image from the same source and reflected by the large opposite surface of the windshield.

 In a particular embodiment of the invention, the windshield comprises a pair of glass layers fixed to one another by an intermediate sheet of thermoplastic material whose thickness is thinner than one of its edges at its opposite edge. The decreasing section configuration of the intermediate layer may be obtained by casting the intermediate layer in the desired configuration or by subjecting said intermediate layer to a differential stretching to give it the desired shape.When the glass layers and the decreasing cross-sectional layer are assembled and laminated into a laminated unitary structure, the large opposite surfaces of the laminated structure are non-parallel and offset by a predetermined angle, so that the images that come from the display source and are reflected by opposite large surfaces of the laminated structure are substantially superimposed on one another.

 Fig. 1 is a diagram of a collimator steering system for a vehicle.

 Fig. 2 is a partial view in section on a larger scale, corresponding to FIG. 1 and showing a driving collimator using a windshield of the state of the art.

 Fig. 3 is a partial view in section on a larger scale, corresponding to FIG. i and showing a driving collimator using a windshield having the features of the present invention.

 Fig. 4 is an exploded sectional view of an alternative embodiment of the invention.

 The present invention relates to the elimination of dual image formation in a driving collimator system which uses an automotive windshield as a combiner, but it is understood that the present invention can be applied to any type of combiner having a laminated structure where the formation of double images must be eliminated.

 From what is shown in FIG. 1, the driving collimator system 10 comprises a motor vehicle windshield 12, an image source 14 and a projection assembly 16, preferably mounted immediately below the upper surface of the vehicle instrument panel 18 and arranged between the image source 14 and the windshield 12. Light rays, which emanate from the image source 14, are projected onto the windshield 12, which serves as a combiner according to what will be described later, and they are reflected in the field of view of the driver 20 of the vehicle.The light rays projected on the windshield 12 are collimated so as to create a virtual image in front of the car, preferably at a distance of 3 to 15 m (10 at 50 ft.) approximately ahead of the windshield 12.

 Although this is not a limitation of the present invention, the image source 14 is preferably a liquid crystal transmssion display device tLCD) which is suitably illuminated to project information-carrying light rays through 1 the projection assembly 16, on the windshield 12 at a location in the direct line of sight of the driver, while allowing a peripheral vision of the outside real world while the driver 20 monitors the display. It is conceivable that other viewing locations also provide an effective surveillance display on the windshield of the vehicle. The displayed image shown here) may include numerical or graphic symbols indicating for example the speed of the vehicle, the level of the vehicle. fuel, the number of engine revs, the temperature, and warning symbols.

 The following discussion will focus on the use of a prior art windshield as a combiner in a collimator system that projects an image & a finite distance ahead of the windshield. In particular, to refer to FIG. 2, the windshield 30 represents an assembly whose large opposite inner and outer surfaces are parallel to each other. More specifically, the windshield 30 comprises an outer glass layer 32 joined to an inner glass layer 34 by an intermediate layer 36. Because the thickness of the intermediate layer 36 is uniform and the large surfaces opposite of each glass layer are substantially parallel to each other, i.e. the inner surface 37 of the layer 32 is parallel to its outer surface 38 and the inner surface 39 of the layer 34 is parallel to its outer surface 40, the large outer surface 38 of the glass layer 32 is parallel to the large outer surface 40 of the glass layer 34 after the glass layers 32, 34 and the intermediate layer 36 have been counteracted. glues to form a laminated unitary structure. Although this is not a limitation of the invention, it will be appreciated for purposes of illustration in the following description that the surfaces 38 and 40 are planar. However, these surfaces may not be flat, as will be seen later.

 To continue to refer to fig. 2, a light beam A from the image source 14 is directed along the line 42 and a portion of the light is reflected by the surface 40 of the layer 34, along the line 44 to the eye 46 of the driver 20 of the vehicle.

Other light rays from the source 14 are directed along other lines. For example, a radius B is directed along the line 48 and reflected by the surface 40 along the line 50. However, the radius B along the line 50 is not directed towards the eye 46, which which will not be perceived by the observer 20. A portion of the light beam B which is directed along the line 48 will enter the windshield 30 and be refracted along the line 52. The gap angular between the lines 48 and 52 depends on the refraction angle when the light ray passes from the air to the glass layer 34. In turn, the refraction angle depends in part on the angle of incidence of the radius B on the surface 40 and relative densities of air and glass.Beam B passes through the layers of the windshield 30 and part of the light beam B is reflected by the surface 38 of the layer 32 along the line 54. It will be assumed that the refractive index of the intermediate layer 36 is the same as that of the glass layers 32 and 34, so that the ra The light yams do not undergo deformation by passing through the windshield layers 30 along the lines 52 and 54.

A portion of the light beam B leaves the windshield 30 at the surface 40 of the glass layer 34, where the direction of the light is changed again as a result of the difference in refractive indices between the windshield 30 and the according to what has been stated above, and is directed along the line 56 to the eye 46. By the fact that the light rays A and
B received by the eye 46 from the image source 14 follow two different lines, namely the lines 44 and 56, the observer 20 will perceive two images shifted, while there is in fact only a single image source 14. The first image 58, or virtual image, is the image seen by the observer 20 from the light directed along line 44. The second image 60 is the image seen by the observer 20 from the light directed along the line 56.When the observer looks at the two images, the virtual image 58 will appear brighter than the second image 60, because a greater part of the light coming from the image source 14, initially directed along line 42, will be directed along line 44, in comparison with the amount of light that is initially directed along line 48 and which is ultimately directed along line 56 to the observer 20. This situation, consisting of seeing two staggered images, is it is known as image splitting or ghost imaging and occurs when the outer surfaces of the windshield, i.e. the surfaces 38 and 40 of the windshield 30> are parallel to each other. other.

 In order to reduce the degree of image splitting in the windshield 30, it is provided according to the present invention to modify the structure of the windshield. Although this is not a limitation of the present invention, from FIG. 3 which illustrates a preferred embodiment of the present invention, the windshield 130 comprises an outer glass layer 132 joined to an inner glass layer 134 by an intermediate layer 136 between the large inner surfaces 137 and 139 of the layers 132 and 134 respectively . The intermediate layer 136 is manufactured in such a way that there is a gradual thinning of its thickness, that is to say that the material of the intermediate layer gradually decreases in thickness from one of its edges to its edge. As a result of this "wedge" shape of the intermediate layer, when the components of the windshield are assembled and laminated, the large outer surface 138 of the glass layer 132 and the large outer surface 140 of the layer of glass 134 are not parallel. It has been found that by selecting the degree of mutual divergence of the glass layers 132 and 134 of the windshield 130, it is possible to reduce the formation of a double image which is observed when using a windshield as shown in FIG. 2 as a combiner. The effective corner angle X required to reduce the formation of a dual image depends in part on the thickness of the windshield, the windshield material and the relative positions and orientations of the image source 14, Breeze 130 and the driver 20 of the vehicle. While not a limitation of the present invention, the intermediate layer 136 may be cast in place to produce the desired corner angle X. Alternatively, the intermediate layer 136 may be subjected to differential stretching in any manner known in the art, particularly as described in U.S. Patent No. 4,201,351 (Tolliver) and US Pat. No. 4 554 713 <Chabel) which are hereby incorporated by reference.

To refer again to FIG. 3, the light ray
A 'from the image source 14 is directed along the line 142 and reflected by the surface 140 along the line 144 to the eye 46 of the observer. Another light beam B 'is directed along the line 148 and, as previously indicated, a portion of the light beam is reflected by the surface 140 along the line 150, so that it is not not seen by the observer 20. The remaining portion of the B 'ray is refracted through the glass layers 132, 134 and the intermediate layer 136 along the line 152, similar to what has been indicated above> then it is reflected from the surface 138 of the glass layer 132 along the line 154 and refracted leaving the windshield 130 to the eye 46 of the observer.However, unlike the windshield 30 of the fig. 2 where the line 56 followed by the radius B has a different orientation from that of the line 44 followed by the radius A, the corner angle X in FIG. 3 is such that the refracted light from the light beam B 'leaves the windshield 130 along the line 144, that is to say it is superimposed on the light of the radius h' reflected by the surface 140 of the glass layer 134. Accordingly, the images seen by the observer 20 and resulting from the light rays A 'and
B 'are superimposed on one another, so that there is only one image 158.

 It should be noted that in a windshield, the surfaces 138 and 140 of the glass layers 132 and 134, respectively, are often not flat, but rather have a curved shape. However, the relative degree of curvature of the windshield 130 in the small region used as the combiner is relatively small, so that the region constituting the combining portion of the windshield 130 is almost flat. In addition, if this is necessary because of an excessive curvature of the windshield in the area serving as a combiner, it is possible to deform the image from the image source 14, for example by incorporating lens systems. additional (not shown) in the projection assembly 16 (shown only in Fig. 1) to compensate for the curvature of the windshield surfaces.

 In a particular embodiment of the invention, the windshield 130 comprises 0.2 mm (0.090 in.) Thick glass layers and two intermediate layers of polyvinylbutryl. Each intermediate layer initially has a thickness of 0.05 mm <0.020 in.) And has been subjected to differential stretching, so that each intermediate layer has a thinning of about 0.076 mm (0.003 in.) Over a width of 91 mm. cm (36 in.)> of the intermediate layer, for a combined thickness difference of about 0.152 mm (0, 006 in.) from top to bottom when these layers are incorporated into the windshield 130. To refer in fig. 1, it was found that a windshield thus constructed, mounted in a vehicle with an installation angle Y of about 30 "and an angle of incidence Z of about 65 between the windshield 12 and the light rays from the image source, significantly reduced the degree of dual imaging in a collimating flight control system compared to a conventional non-wedge windshield .

 While the windshield configuration 130 of the present invention as shown in FIG. 3, comprises two glass sheets, each of which has large generally parallel opposed surfaces and an intermediate layer of decreasing cross-section, it is obvious to those skilled in the art, on the basis of the teachings of the present description, that other windshield configurations can be used to give one. a wedge-shaped windshield configuration similar to that shown in FIG. 3.In particular, to refer to fig. 4, one or the other of the glass layers 232 and 234 may have a decreasing section, so that when the assembly 230 is laminated to form a unitary laminated structure using a In the unstretched intermediate layer 236, the opposing surfaces 238 and 240 of the windshield 230 are non-parallel and are oriented relative to each other so as to eliminate double image formation. It is furthermore conceivable that only one or more intermediate layers of decreasing section be used in combination with one or more layers of decreasing section glass, so that the final laminated assembly gives the windshield structure having the configuration required to reduce dual imaging.

 The forms of the invention which have been described herein represent preferred embodiments and different variations thereof, presented for the purpose of illustration. It is understood that various modifications can be made without departing from the scope of the invention.

Claims (20)

 1.- Flaky ice including.  characterized by means (1S6) for securing said first layer to said second layer such that the opposing large outer surfaces (138,140) of said crystal <130) are non-parallel and oriented relative to each other so that an image projected by a display source (14) and reflected by an external surface <138) of said mirror is substantially superimposed on an image projected by said display source and reflected by the large opposite external surface (140) of said ice.  a second rigid layer (134);  a first rigid layer (132);  2.- Flaky ice cream comprising:  a first layer (132) having opposing large internal (C137) and external (138) surfaces;  a second layer (134) having large inner (139) and outer (140) opposite surfaces;  characterized by means (136) for securing said large inner surface (137) of said first layer (132) to said large inner surface (139) of said second layer (134) so that said large outer surfaces (138 and 140 ) said layers are non-parallel to one another and oriented so that an image projected by a display source C14) and reflected by said outer surface (138) of said first layer (132) is substantially superimposed on an image projected by said display source and reflected by said large outer surface (140) of said second layer (134).  3. Ice according to claim 2, characterized in that said large areas of said first and second layers (132 and 134) are non-planar.  4. Ice according to claim 2, characterized in that said outer surface C138 or 140) of each of said layers (132 and 134) is parallel to said inner surface <137 or 139) of said corresponding layer.  5. Ice according to claim 4, characterized in that said layers (132 and 134) are glass layers and said fixing means (136) are a decreasing section sheet of a thermoplastic material.  6. Ice according to claim 5, characterized in that said large areas of said first and second layers (132 and 134) are non-planar.  7. Ice according to claim 2, characterized in that at least one of said layers (132 and 134) has a gradually decreasing thickness.  8. Ice according to claim 7, characterized in that said layers (132 and 134) are glass and said fixing means <136) are a sheet of a thermoplastic material.  9. Ice according to claim 8, characterized in that said large areas of said first and second layers (132 and 134) are non-planar.  10. Ice according to claim 8, characterized in that said sheet <136) of thermoplastic material has a gradually decreasing thickness.  11. Collimator driving system for a vehicle, comprising: means (14) for projecting a desired display, and a windshield (130), characterized in that the windshield has opposite first and second large surfaces ( 138, 140) non-parallel, oriented relative to each other so that an image projected by said display means and reflected by said first large surface (138) of said windshield is substantially superimposed on said image reflected by said second large surface (140) of said windshield C130).  12. A system according to claim 11, characterized in that said large opposite surfaces (138 and 140) of said windshield tel30) are non-planar.  13.- System according to claim 11, characterized in that said windshield cl30) comprises first and second layers (132 and 134) transparent and rigid, and means (136) for uniting together said first and second layers to form a unitary structure.  14. The system of claim 13, characterized in that the large opposite surfaces (137 and 138 or 139 and 140) of each of said layers (132 and 134) are substantially parallel to each other.  15. The system of claim 14, characterized in that said transparent layers (132 and 134), are glass layers and said union means (136) comprise a progressively decreasing section sheet of a thermoplastic material.  16. The system of claim 15, characterized in that said large areas of said first and second layers (132 and 134) are non-planar.  17.- System according to claim 13, characterized in that at least one of said layers (132 and 134) has a gradually decreasing thickness.  18. The system of claim 17, characterized in that said transparent layers <132 and 134) are glass layers and said union means (136) comprises a sheet of a thermoplastic material.  19. The system of claim 18, characterized in that said large areas of said first and second layers (132 and 134) are non-planar.  20. The system of claim 18, characterized in that said sheet <136) of thermoplastic material has a gradually decreasing thickness.