阅读说明：本技术 用于机动车辆驾驶员的平视显示系统的投影设备及对应的系统 (Projection device for a head-up display system for a driver of a motor vehicle and corresponding system ) 是由 F.格兰德克勒克 P.默米洛德 A-C.佩特鲁奇 于 2019-06-06 设计创作，主要内容包括：本发明涉及一种投影设备(1),该设备包括：生成具有设定的主方向(15)的照明光束的至少一个装置(2)；将由生成装置(2)生成的照明光束的光散射成散射的光束的构件；以及具有两个相对的面的平坦的成像屏幕(4),入射面接收散射的光束,而相对的出射面产生设定的主方向(16)的显示光束；该散射光的构件由在生成装置(2)的出口与成像屏幕(4)之间放置的平坦的漫射器(3)构成。根据本发明,漫射器(3)平行于成像屏幕(4)并且施加为抵靠成像屏幕(4)的入射面,漫射器(3)和成像屏幕(4)相对于由生成装置(2)生成的照明光束的主方向(15)倾斜,并且漫射器(3)的光散射指示量对于与由生成装置(2)生成的照明光束的主方向(15)对准的方向具有最大值。还呈现了一种包括该设备的平视显示系统。(The invention relates to a projection device (1), comprising: at least one device (2) generating an illumination beam having a set main direction (15); a means for scattering light of the illumination beam generated by the generation device (2) into a scattered beam; and a flat imaging screen (4) having two opposite faces, the entrance face receiving the scattered light beam and the opposite exit face generating a display beam of a set main direction (16); the means for scattering light is constituted by a flat diffuser (3) placed between the outlet of the generating device (2) and the imaging screen (4). According to the invention, the diffuser (3) is parallel to the imaging screen (4) and applied against an entrance face of the imaging screen (4), the diffuser (3) and the imaging screen (4) are inclined with respect to a main direction (15) of the illumination beam generated by the generating means (2), and the light scattering indicative quantity of the diffuser (3) has a maximum value for a direction aligned with the main direction (15) of the illumination beam generated by the generating means (2). A head-up display system including the apparatus is also presented.)

1. A projection device (1) comprising at least:

-generating means (2) for generating an illumination beam having a determined main direction (15),

-a member for scattering the light of said illumination beam generated by the generation means (2) into a scattered beam, and

-a flat imaging screen (4) comprising two opposite faces, an input face receiving said scattered light beam and an opposite output face producing a display beam having a determined main direction (16),

a light scattering member constituted by a flat diffuser (3) arranged between the output of the generating means (2) and the imaging screen (4),

it is characterized in that the preparation method is characterized in that,

-the diffuser (3) is parallel to the imaging screen (4),

-the diffuser (3) and the imaging screen (4) are inclined with respect to a main direction (15) of the illumination beam generated by the generating means (2), and

-the light scattering indicative quantity of the diffuser (3) has a maximum value for a direction aligned with a main direction (15) of the illumination light beam generated by the generating means (2).

2. A projection device (1) as claimed in claim 1, characterized in that the diffuser (3) is applied against an input face of the imaging screen (4).

3. The projection device (1) according to claim 1, characterized in that the diffuser (3) is applied against the input face of the imaging screen (4) by a block of material of uniform thickness, which is sandwiched between the diffuser (3) and the imaging screen (4).

4. A projection device (1) according to claim 3, wherein the block of material is selected from a block of homogeneous or heterogeneous material.

5. A projection device (1) as claimed in any one of the preceding claims, characterized in that the means (2) for generating an illumination beam comprise a reflector (7) consisting of a hollow and internally reflecting tube.

6. A projection device (1) as claimed in claim 5, characterized in that the diffuser (3) is arranged against a downstream end of the reflector (7).

7. A projection device (1) as claimed in claim 5 or claim 6, characterized in that the reflector (7) is metallic and forms a heat radiator of the means (2) for generating the illumination beam.

8. A projection device (1) according to any of the preceding claims, wherein the diffuser (3) and the imaging screen (4) are inclined at an angle in the range of 5 ° to 30 ° with respect to the normal of the main direction (15) of the illumination beam.

9. Head-up display system comprising a projection device according to any one of claims 1 to 8, a partial reflector (13) and an optical system (12) designed to transmit the display light beam in the direction of the partial reflector (13).

10. The heads-up display system of claim 9, wherein the partial reflector is a windshield, and wherein the diffuser and the imaging screen are tilted at an angle of approximately 10 ° with respect to a normal to a primary direction (15) of the illumination beam.

11. Head-up display system according to claim 9, wherein the partial reflector is a combiner and wherein the diffuser and the imaging screen are inclined at an angle of approximately 20 ° with respect to a normal to a main direction of the illumination beam (15).

Technical Field

The present invention generally relates to the field of driving assistance for motor vehicles. The invention relates more particularly to a projection device intended for a head-up display system for a driver of a motor vehicle and to a corresponding system.

Background

In order to make it easier and safer to drive motor vehicles, it is desirable to avoid drivers having to divert their line of sight from the road on which they are traveling.

For this reason, it is known to use head-up display systems that allow head-up display, designed to project information (speed of the vehicle, direction to be taken, etc.) flush with the driver's line of sight in order to assist them in driving. For this purpose, the device projecting this information is implemented in a head-up display system.

The projection device mainly comprises a device for generating a light beam and an imaging screen. In general, a fold mirror is used to reflect an image produced by a projection device to a partially reflective plate that is disposed flush with the line of sight of the driver while driving. A fold mirror may be incorporated into the projection device.

One problem encountered with the known system is that it is difficult to achieve a uniform illumination of the projected information. In addition, stray reflections from external light sources off the optical elements of the head-up display system and in particular its projection apparatus must be avoided. Among these external light sources, sunlight may be reflected at certain angles by the optical elements of the projection device and impair the driver and the reading of the projected information.

The present invention may solve these problems by proposing a specific arrangement of optical elements of a projection device.

Disclosure of Invention

Therefore, according to the present invention, a projection device is proposed, comprising at least:

-means for generating an illumination beam having a determined main direction,

-a member for scattering the light of the illumination beam generated by the generating means into a scattered light beam, and

a flat imaging screen comprising two opposite faces, an input face receiving the scattered light beam and an opposite output face producing a display beam having a determined main direction,

the light scattering means consists of a flat diffuser arranged between the output of the generating device and the imaging screen.

According to the invention, the diffuser is parallel to the imaging screen, the diffuser and the imaging screen are inclined with respect to the main direction of the illumination beam generated by the generation means, and the light scattering indicator of the diffuser has a maximum value for a direction aligned with the main direction of the illumination beam generated by the generation means.

Since the optical scattering indicia are aligned with the primary direction of the illumination beam, the optical efficiency of the system is optimized, while portions of the diffuser and imaging screen can be tilted and parallel (or even pressed against each other), thereby avoiding viewing stray images in the virtual image produced by the head-up display system.

It is understood that in the context of the present invention, the terms "upstream", "downstream" or "input", "output" or their equivalents (indicating the position of the various optical components along the optical path) are substantially determined with reference to the direction of propagation of light from the light source of the device generating the light beam along the optical path towards the driver.

Other non-limiting and advantageous features of the device according to the invention (which may be employed individually or in technical combination) are as follows:

the diffuser is flat and comprises opposite main faces that are flat and parallel to each other,

the imaging screen is flat and comprises opposite main faces that are flat and parallel to each other,

-the imaging screen is of the transmissive type,

the diffuser is made of molded or injected plastic,

-the diffuser is made of a plastic selected from the group consisting of polyacrylates and polycarbonates,

-a diffuser is applied against the input face of the imaging screen,

-applying a diffuser against the input face of the imaging screen by a block of material of uniform thickness, the block of material being sandwiched between the diffuser and the imaging screen,

-the pieces of material are selected from pieces of homogeneous or heterogeneous material,

the block of material consists of a homogeneous transparent plastic,

the block of material is constituted by a network of optical fibers parallel to each other and perpendicular to two parallel faces of the block, so as to form a collimated light guide,

the means for generating the illumination beam comprise a reflector consisting of a hollow and an internal reflection tube,

the reflector comprises an upstream end close to the light source and a downstream end opposite thereto,

the reflector forms an illumination beam at the output of the means for generating an illumination beam with a divergence reduced compared to the main direction of the illumination beam, said divergence being between 0 ° and 20 ° (inclusive),

preferably, the divergence is between 0 ° and 12.5 ° (inclusive),

-the diffuser is arranged against the downstream end of the reflector,

the shape of the imaging screen is circular, square or rectangular,

the shape of the diffuser is the same as the shape of the imaging screen,

the shape of the diffuser is circular, square or rectangular,

the cross-sectional shape of the reflector is the same as the shape of the imaging screen,

the cross-sectional shape of the reflector is circular, square or rectangular,

the reflector is metallic and forms the heat radiator of the means for generating the illumination beam,

-the diffuser and the imaging screen are inclined at an angle between 5 and 30 with respect to the normal to the main direction of the illumination beam,

-the diffuser and the imaging screen are inclined at an angle between 10 and 20 with respect to the normal to the main direction of the illumination beam,

the diffuser and the imaging screen are inclined at an angle of approximately 12.5 ° with respect to the normal to the main direction of the illumination beam,

in the case of the partially reflecting plate being a windscreen, the diffuser and the imaging screen are inclined at an angle of approximately 10 ° with respect to the normal to the main direction of the illumination beam,

in case the partially reflecting plate is a combiner, the diffuser and the imaging screen are tilted at an angle of approximately 20 ° with respect to the normal to the main direction of the illumination beam,

the projection device further comprises an output folding mirror downstream of the imaging screen, that is to say on the output face side of the imaging screen.

-the output folding mirror is flat,

the output folding mirror is not flat,

the output folding mirror is free-form,

the device further comprises an intermediate folding mirror between the output of the reflector and the diffuser, in order to change the direction of the light beam between the means generating the illumination beam and the diffuser,

the intermediate folding mirror is flat,

the intermediate folding mirror is not flat

The intermediate folding mirror being free-form

The projection device comprises an intermediate folding mirror and an output folding mirror,

-if an intermediate folding mirror is arranged in the projection device, the output folding mirror is omitted,

-the vehicle is selected from: cars, trucks, buses or coaches.

The invention also relates to a head-up viewing system for viewing a light display by a driver of a vehicle, said system comprising a device for projecting a display light beam according to the invention and an optical system designed to project the display light beam in the direction of a partial reflector.

In other words, this is a head-up display system comprising a projection device according to the invention, a partial reflector and an optical system designed to transmit a display light beam in the direction of the partial reflector.

Other non-limiting and advantageous features of the system according to the invention (which may be employed individually or in technical combination) are as follows:

the head-up display system further comprises an output folding mirror downstream of the imaging screen of the projection device,

the projection device further comprises an output folding mirror reflecting the light path towards a partially reflective display panel of the system,

in the system, the partially reflective display panel is a partially reflective panel specific to the head-up display system and mounted in the vehicle, or else a windshield of the vehicle.

In the system, the partially reflective display panel is colored or opaque,

in the system, the windshield includes, in the area where the partial reflector is formed, a treatment aimed at avoiding ghost images.

Detailed Description

The following description, with reference to the drawings provided as non-limiting examples, will assist in understanding the content of the invention and how it may be carried into effect.

In the drawings:

fig. 1 shows a schematic view of a projection device according to the invention and intended for a head-up display system for a vehicle driver, an

Fig. 2 shows a schematic view of a head-up display system comprising a projection device according to the invention.

Fig. 1 shows a projection device 1 for projecting a light beam representing an image, the projection device 1 comprising, along an optical path from upstream to downstream: a device 2 for generating an illumination beam having a main direction 15, a diffuser 3 for generating a scattered beam, and an imaging screen 4 for generating a display beam having a main direction 16. The diffuser 3 and the imaging screen 4 are flat elements parallel to each other and preferably adjacent to each other. However, it may be provided that the diffuser 3 and the imaging screen 4 are separated by a space filled with a transparent material, in particular a uniform/constant thickness block made of a homogeneous or inhomogeneous material and for example made of a transparent homogeneous plastic, or that the block comprises a network of optical fibers parallel to each other and perpendicular to two parallel faces of the block so as to form a collimating light guide. The block is then sandwiched between a diffuser and an imaging screen, which are always parallel to each other.

The imaging screen 4 may form an image intended to be projected. The imaging screen 4 does not deflect the light beam passing through it: the main direction of the light beam passing through the inclined imaging screen remains practically unchanged and is at least parallel between the input and the output of the imaging screen. In particular, the imaging screen has flat and parallel input/upstream and output/downstream faces, and if it is considered for the sake of simplicity to be a homogeneous medium (or a succession of such media), there is a slight shift/translation of the rays not perpendicular to the interfaces, due to the inclination of the imaging screen and therefore to the fact that their paired optical interfaces produce a compensated refraction. The imaging screen 4 thus comprises two opposite faces, an input face receiving the scattered light beam and an opposite output face generating the display light beam. The imaging screen 4 may be of any transmissive type, for example a passive or active liquid crystal (or LCD of "liquid crystal display"), and is preferably of the thin film transistor (or TFT) type.

The means 2 for generating an illumination beam comprise at least one illumination led 5 mounted on a printed circuit board 6 and a reflector 7. More generally, the light source may be formed by a plurality of light emitting diodes carried by a printed circuit board or by a single light emitting diode of suitable power. The reflector 7 forms an internally reflective light guide intended to produce a substantially collimated illumination beam with a determined main direction 15, having a relatively low divergence, by reflecting at least some of the light rays produced by the light source 5. In one variation, the light guide is non-internally reflective. The generating means 2 can thus generate an illumination beam whose main direction 15 is determined and substantially perpendicular to the printed circuit board 6 in fig. 1, the main axis of the emission cone of the one or more illumination light emitting diodes 5 being perpendicular to the printed circuit board 6. Thus, in the illustration of fig. 1, the main axis 15 of the illumination beam is vertical.

The diffuser 3 and the imaging screen 4 are inclined (for example by an angle between 5 ° and 30 °, here 12.5 °) with respect to the main direction 15 of the illumination beam, that is to say that the main direction 15 of the illumination beam does not perpendicularly illuminate the input face of the diffuser: there is a non-zero angle of incidence (normal to the plane of the diffuser). In fact, the inclination may depend on how the partial reflecting plate 13 is formed: if it is a windscreen an angle of approximately 10 is selected, if it is a dedicated combiner an angle of approximately 20 is selected. It will be recalled that this angle is the angle formed by the diffuser 3 and the imaging screen 4 with respect to the normal of the main direction 15 of the illumination beam.

The diffuser 3 is preferably positioned against the downstream end of the reflector 7 and therefore has an inclined aperture, said reflector 7 having the general shape of a truncated cone with a narrow apex upstream on the printed circuit board 6 side and a wide base downstream inclined (not perpendicular) to the main axis of said reflector. The wide downstream base of the reflector 7 (which is open) is applied against the diffuser 3 over its entire periphery. Because the diffuser 3 is so positioned against the downstream end of the reflector 7, the interior region of the reflector 7 (between the upstream printed circuit board 6 and the one or more light emitting diodes 5 and the downstream diffuser 3) is substantially isolated from the environment, preventing dust or other dirt from being able to enter therein.

In some variants, the shape of the reflector 7 is adapted so as to homogenize the distribution of the light on the upstream input face of the diffuser 3. The reflector 7 may form a heat radiator intended to radiate/remove heat generated by the one or more light emitting diodes 5 of the device 2 generating the illumination beam.

The diffuser 3 is a member for scattering the light of the illumination light beam generated by the generation device 2. The diffuser is a translucent plate comprising an input face and an output face, and the diffuser is designed to scatter light incident on the input face through the output face in accordance with the already mentioned optical scattering indications. The input face of the diffuser 3 (or translucent plate) faces the light source 5; the output face of the diffuser 3 (or translucent plate) faces the input face of the imaging screen 4 (and is here pressed into contact with the input face of the imaging screen 4).

The diffuser 2 produces a scattered light beam with a determined main direction at the output depending in particular on the optical scattering indicator quantity 8 of the diffuser. This light scattering indicator quantity 8 defines the light intensity as a function of the viewing angle at the output of the diffuser 3. Thus, the scatter indication has a maximum value for a direction corresponding to the main direction 16 of the scattered beam. In the context of the present invention, the optical scattering indicator quantity 8 is defined such that the main direction of the scattered light beam (leaving the diffuser) is inclined with respect to the normal of the plane of the diffuser 3 (or translucent plate).

In order to obtain a scattering indication quantity having a maximum value for a direction inclined with respect to a direction perpendicular to the plane of the diffuser 3, one face of the diffuser 3 is provided with a diffractive optical element (or DOE).

Such diffractive optical elements include, for example, arrays of microlenses and/or arrays of prisms.

The structural features of these diffractive optical elements (for example, the shape and diameter of the microlenses and/or the apex angle and length of the basic pattern of prisms) are determined so as to obtain a desired optical prescription having a maximum value for a direction inclined with respect to a direction perpendicular to the plane of the diffuser 3, as already indicated.

The diffuser 3 equipped with diffractive optical elements can be made of plastic, for example, polycarbonate or poly (methyl methacrylate), for example, by compression molding.

For this purpose, a molding is used, which has the desired dimensions of the diffuser and which has a pattern on one face corresponding to the diffractive optical element described above. Plastic is injected into the mold and pressure is applied so as to imprint the pattern of the mold into the plastic, whereby a diffractive optical element can be obtained.

As a variant, a holographic diffuser may be used in order to obtain the scattering according to the above-mentioned optical scattering indications.

As can be seen from fig. 1, the light scattering indicator quantity of the diffuser 3 has a maximum for a direction aligned with the main direction 15 of the illumination light beam, thus making the main direction 16 of the scattered light beam parallel to the main direction 15 of the illumination light beam.

The type of light scattering produced by the diffuser can be selected from the following types of scattering: linear, circular, gaussian circular, elliptical, or other scattering types. The diffuser may be made of plastic, for example in particular injection molded.

The overall optical pointing quantity 10 of the projection device 1 can be defined in all the elements forming the projection device 1 (generating means 2, diffuser 3 and imaging screen 4) and has a maximum value for a determined main direction, for example with respect to the plane of the printed circuit board 6. In fig. 1, the overall optical pointing quantity 10 has a maximum value for a direction perpendicular to the plane of the printed circuit board 6.

It is also possible to define a target optical pointing quantity 9 desired to be obtained, and this target optical pointing quantity 9 corresponds to a value suitable for the head-up display system in which the projection apparatus is to be installed. The optical scattering indicator quantity 8 will thus be selected to give an overall optical indicator quantity 10 in the projection device 1 corresponding to the desired target optical indicator quantity 9.

Fig. 2 shows a head-up display system 11 intended for adaptation in a vehicle, for example a motor vehicle of the automotive type.

The head-up display system comprises an image projection device 1 driven by a computer (not shown) and an optical projection system essentially consisting of an output folding mirror 12 and a partial reflector 13, which are intended to project an image towards a driver 14 of the vehicle along a projection axis 17 of the image between the output folding mirror 12 and the partial reflector 13 and then along a projection axis 18 of the image between the partial reflector 13 and the driver 14. The partial reflecting plate 13 may be a specific dedicated element or correspond to the windshield of the vehicle. It is understood that in fig. 2, the light beam shown is represented by an axis which is the main direction of said light beam, the cross section of the beam itself may be circular, square or rectangular, or even other shapes, as the case may be.

Since the diffuser 3 and the imaging screen 4 are adjacent in the projection device 2, the mounting and adjustment of these elements is simplified. Furthermore, any stray reflections are avoided which may occur at the optical interfaces of the elements when they are separated from each other or in particular tilted with respect to each other. The fact that the imaging screen 4 is not perpendicular to the illumination and display beams avoids stray reflections, and in particular reflections from sunlight. With this, any reflection from the sunlight is not reflected into the driver's view, but passes to the outside of the output folding mirror 12.

As shown in fig. 2, the imaging screen 4 may generate, under the control of a computer (not shown), an image projected into the field of view of the driver 14 when the line of sight direction of the driver faces the traffic lane and projected into the partial reflection plate 13 located in the same line of sight direction. The head-up display system is more specifically designed to project a virtual image into the field of view of the driver of the vehicle.

To this end, the head-up display system 11 therefore comprises an output folding mirror 12 and a partial reflector 13, the latter being placed in the field of view of a driver 14 of the vehicle. Optionally, the system may further comprise a magnifying lens/refractor (not shown). Preferably, the output folding mirror 12 is incorporated into the projection device 1, but in some variations the folding mirror may be separate.

Preferably, the partial reflector 13 is a combiner arranged in the passenger compartment of the motor vehicle between the windscreen of the vehicle and the eyes of the driver 14. As a variant, the partial reflecting plate 13 should be formed by the windshield itself.

The partially reflective plate 13 in fig. 2 comprises a partially reflective curved optical pane, where the magnifying function is performed. It may be a polycarbonate injected portion that is bent to enlarge the size of the image seen by the driver 14.

A computer (not shown) that prepares an image intended to be projected typically includes a processor and a storage unit, such as a memory including a rewritable non-volatile memory or a hard disk.

The head-up display system shown may display a two-dimensional image, but in some variant embodiments the head-up display system may be supplemented with an autostereoscopic filter, in particular at the output of the imaging screen 4, in order to allow the display of images in virtual three dimensions by the visual depth effect of the driver, the projected images appearing on different planes of the driver 14.

In various embodiments, means are provided for implementing means for magnifying an image projected by an imaging screen, in particular with means as described above, and/or implementing a magnifying lens or a refractor in the path of the projected image. Shape correction means using software and/or using hardware means may also be provided, for example wherein the surface of one or more non-flat folding mirrors and/or at least one additional lens/refractor is designed to take account of the fact that an image may be projected onto a curved surface making it visible. Anti-scatter grids may also be added, for example, downstream of the imaging screen 4 and/or upstream of the diffuser 3.