CN114690411A - Vehicle-mounted imaging device based on MEMS array - Google Patents

Abstract

The invention discloses a vehicle-mounted imaging device based on an MEMS array, which comprises: light source: the device is used for emitting a plurality of parallel lights to form a rough light beam; MEMS micro-galvanometer array mechanism: reflecting the coarse light beam emitted by the light source according to a certain angle; an imaging lens: the MEMS micro-vibration mirror array mechanism is provided with a positive focal length and is used for converging light beams reflected by the MEMS micro-vibration mirror array mechanism into a real image; or the optical fiber has a negative focal length and is used for diverging the light beam reflected by the MEMS micro-vibration mirror array mechanism into a virtual image. The invention has the advantages that: the light source of the parallel coarse light beams is matched with the MEMS micro-vibration mirror array mechanism, so that large eye box range viewing can be realized without a screen, and the space occupied by the MEMS part can be further reduced by adopting the MEMS micro-vibration mirror array mechanism relative to a single MEMS micro-vibration mirror, so that the purpose of small volume and large view field is realized.

Description

Vehicle-mounted imaging device based on MEMS array

Technical Field

The invention relates to a vehicle-mounted imaging device based on a MEMS array.

Background

The AID is called for short by vehicle-mounted aerial imaging equipment, the HUD is different from a conventional head-up display device HUD, the imaging of the HUD is generally positioned outside a front windshield of an automobile, a human eye sight direction forms a virtual image, the AID equipment forms a real image between the front windshield of the automobile and a driver and a passenger, and the AID equipment can be used for performing man-machine interaction with equipment such as gesture recognition besides displaying content.

HUD, AID are used for instrument platform before the car, can improve navigating mate and motormeter's mutual experience, especially when driving at a high speed, can show and reduce the navigating mate because the number of times that watches the instrument and hang down, have improved the security. For HUD, AID device presentations where it is desirable not to obstruct the driving view, the CHUD or other solution with a scatter curtain is less secure.

And the installation of HUD, AID can occupy certain space, and the bigger formation of image size corresponds bigger space and occupies. Under on-vehicle HUD, AID scene, instrument platform space is limited before the car, and this has just restricted HUD, AID equipment's formation of image size. In limited instrument mesa space before the car, the space that can dodge on the upper and lower direction is limited, and the space that can dodge on the horizontal direction is great, and HUD, AID equipment applied to instrument mesa before the car are the trend of future toward the flattening development.

The existing aerial imaging equipment is based on the air projection technology, and mainly comprises:

1. the first is a negative refraction flat plate mode, and an equilarge real image is reconstructed in the air by introducing the negative refraction flat plate and reflecting the inner surface of the front windshield of the automobile;

2. the second is a medium 'screen' mode, a scattering surface (such as a projection curtain) is arranged at an imaging position, and an image formed by a projection light machine is scattered and then scattered to human eyes;

3. the third reflection scheme similar to the head-up display HUD adopts a free-form surface reflector to form a real image;

4. the fourth is a tiny MEMS array based imaging scheme.

With the first negative refraction plate approach, as shown in fig. 1, the real image 4 and the image source 1 are mirrored about the negative refraction plate 8, and the line of sight at the eye box 5 generally extends to the negative refraction plate, which may cause partial occlusion. The first way to solve the problem of shielding is to increase the included angle between the observation sight line and the normal line of the negative refraction flat plate, and simultaneously to make the negative refraction flat plate parallel to the table top of the front instrument of the automobile as much as possible, the area of the negative refraction flat plate is required to be increased rapidly by changing the way, the length of the negative refraction flat plate is easily over 1 meter, and obviously, the method is unrealistic. The second solution that shelters from is, once with the help of the reflection of windscreen before the car, but general windscreen before the car still has 250 ~ 300 mm's distance to the instrument mesa before the car, because negative refraction dull and stereotyped magnification is only 1, then the image source will be far away from the negative refraction dull and stereotyped, so the volume of system is generally great, and under this situation, can form a virtual image that is located windscreen before the car outside, rather than the real image. In addition, due to the technical characteristics of the imaging mode of the negative refraction flat plate, on one hand, obvious stray light exists; on the other hand, the image quality of the image cannot be fine and smooth, and the quality of the image also depends on the distance between the reflective arrays inside the negative refraction flat plate.

In the second medium screen mode, light is scattered by the existence of a layer of medium, so that the image with a large eye box range can be visible under the condition of a smaller aperture angle of projection light. The mode can be adopted only under special conditions, namely, the requirement of image transparency is not met, but the mode of a projection curtain and an air water curtain cannot be used for actually getting on a vehicle due to the fact that the images are not shielded by the air intelligent imaging equipment based on the automobile front instrument platform.

As also shown in fig. 2, which represents a conventional solution, the image source 7 is composed of a two-dimensional array of pixels, and the common image sources are a transmissive LCD screen, a reflective LCOS screen, and a DMD chip. After passing through the imaging lens 3 or the reflective system, the image source reproduces a magnified or reduced real image 4 at a specific position. When the human eyes watch the image at the position of the eye box 5, the requirement of an observation area exists, so that each pixel point on an image source is required to have a certain light-emitting aperture angle, the light-emitting of the pixel point is realized through backlight illumination, and a backlight light source is a light source with a certain light-emitting angle. If the flat light irradiation is carried out at a single angle, the observation in a certain area cannot be realized; the light rays can of course be diverged by adding a diffuser film behind the flat light, but the illumination beam impinging on the image source must be essentially divergent light.

As shown in fig. 3, a small volume solution based on the two-dimensional MEMS10 is provided, because the two-dimensional MEMS10 and the laser light source 9 combination can be small in volume by using the beamlets 11 for imaging, but the different positions of the viewing must be realized by means of the screen 12 with scattering function.

For the third reflection mode similar to the head-up display HUD, the machining precision of the free-form surface reflector is generally required to be high, the field angle of the scheme is generally limited to about 12 × 3 °, a larger field angle is required, a larger optical aperture is required, the scheme also faces the problem of sunlight stray light, the reflectivity of the reflector is more than 85%, and the stray light is more easily observed by human eyes if the stray light exists. At the same time, the solution is generally bulky.

For a fourth imaging scheme based on a micro-MEMS array, such as "spatial imaging device" disclosed in publication No. CN109254410A, a design idea of achieving flattening is given based on the essence of human vision. According to the technical characteristics of the scheme, we also find some limitations of the scheme; firstly, the diameter of the pupil of a human eye is considered, the pupil is generally distributed at 2-8 mm, and if no image is lost when an observation area is watched, the MEMS array is required to be very dense; the larger the distance ratio of the observation area to the area to be displayed to the MEMS array and the area to be displayed is, the denser the MEMS array is, and the number of MEMS is very large under the condition of large-size imaging; secondly, considering the requirement of imaging resolution, forming light rays in different directions of an aerial image point, wherein the aperture of a light beam is small enough; thirdly, the number of fibers and MEMS array elements is the same, which is extremely large in view of resolution requirements.

Disclosure of Invention

The invention aims to provide a vehicle-mounted imaging device based on an MEMS array, which can effectively solve the problems of large volume and small field of view of the conventional vehicle-mounted imaging device.

In order to solve the technical problems, the invention is realized by the following technical scheme: an on-board imaging device based on a MEMS array, comprising:

light source: the device is used for emitting a plurality of parallel lights to form a rough light beam;

MEMS micro-galvanometer array mechanism: reflecting the coarse light beam emitted by the light source;

an imaging lens: the MEMS micro-vibration mirror array mechanism is provided with a positive focal length and is used for converging light beams reflected by the MEMS micro-vibration mirror array mechanism to form a real image; or the optical fiber has a negative focal length and is used for diverging the light beam reflected by the MEMS micro-vibration mirror array mechanism into a virtual image.

Preferably, at least one beam splitter is further arranged on a light path between the light source and the MEMS micro-vibration mirror array mechanism.

Preferably, a beam splitter is further arranged on a light path between the light source and the MEMS micro-vibration mirror array mechanism, one part of a coarse light beam emitted by the light source is reflected to the MEMS micro-vibration mirror array mechanism through the beam splitter, and the other part of the coarse light beam penetrates through the beam splitter.

Preferably, the beam splitter has a light transmittance of 50% and a reflectance of 50%.

Preferably, two beam splitters arranged in parallel are further arranged on a light path between the light source and the MEMS micro-vibration mirror array mechanism and are respectively a first beam splitter and a second beam splitter, one part of a coarse light beam emitted by the light source is reflected to the MEMS micro-vibration mirror array mechanism through the first beam splitter, the other part of the coarse light beam irradiates the second beam splitter through the first beam splitter, one part of the coarse light beam irradiating the second beam splitter is reflected to the MEMS micro-vibration mirror array mechanism, and the other part of the coarse light beam irradiates the second beam splitter.

Preferably, the first beam splitter has a light transmittance of 75% and a reflectance of 25%; the second beam splitter had a light transmittance of 50% and a reflectance of 50%.

Preferably, the MEMS micro-galvanometer array mechanism includes a plurality of MEMS micro-galvanometers arranged in a rectangular array.

Preferably, the imaging lens has a positive focal length, and the imaging lens is a fresnel lens or a fresnel lens group.

Preferably, the imaging lens has a negative focal length, and the imaging lens is a concave lens or a combination of a concave lens and one or more lenses.

Preferably, the light beam emitted by the light source is a monochromatic light beam, or the light beam emitted by the light source is R, G, B three-color mixed light beam.

Compared with the prior art, the invention has the advantages that: when the imaging lens has a positive focal length, aerial imaging is realized by imaging real images, and man-machine interaction is facilitated; and when the imaging lens has a negative focal length, the virtual image will be presented for use as a HUD. The light source of the parallel coarse light beams is matched with the MEMS micro-vibration mirror array mechanism, so that large eye box range viewing can be realized without a screen, and the space occupied by the MEMS part can be further reduced by adopting the MEMS micro-vibration mirror array mechanism relative to a single MEMS micro-vibration mirror, so that the purpose of small volume and large view field is realized.

Drawings

FIG. 1 is a schematic diagram of a conventional negative refraction plate;

FIG. 2 is a schematic diagram of a prior art aerial imaging system;

FIG. 3 is a schematic diagram of a prior art two-dimensional MEMS scheme;

FIG. 4 is a schematic diagram of a first embodiment of the vehicle-mounted imaging device based on the MEMS array, which uses a positive focal length imaging lens according to the present invention;

FIG. 5 is a schematic structural diagram of a MEMS micro-galvanometer array mechanism adopted in the MEMS array-based vehicle-mounted imaging device of the invention;

FIG. 6 is a schematic diagram of a second embodiment of the vehicle-mounted imaging device based on the MEMS array, which uses a positive focal length imaging lens according to the present invention;

FIG. 7 is a schematic diagram of a third embodiment of the vehicle-mounted imaging device based on the MEMS array, which uses a positive focal length imaging lens.

FIG. 8 is a schematic diagram of a fourth embodiment of the vehicle-mounted imaging device based on the MEMS array according to the invention, wherein a negative focal length imaging lens is adopted.

The reference signs are: the device comprises a light source 1, an MEMS micro-vibration mirror array mechanism 2, an MEMS micro-vibration mirror 21, an imaging lens 3, a real image 4, an eye box 5, a beam splitter 6, a first beam splitter 61, a second beam splitter 62, an image source 7, a negative refraction flat plate 8, a laser light source 9, a two-dimensional MEMS10, a thin beam 11, a screen 12 and a virtual image 13.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

The first embodiment is as follows:

referring to fig. 4 and 5, the embodiment of the MEMS array based vehicle-mounted imaging apparatus of the present invention includes: the MEMS micro-vibration mirror array mechanism comprises a light source 1, an MEMS micro-vibration mirror array mechanism 2 and an imaging lens 3, wherein the light source 1 is used for emitting a thick light beam formed by a plurality of parallel lights, the inclined angle irradiates the MEMS micro-vibration mirror array mechanism 2, the light beam emitted by the light source 1 covers the surface of the whole MEMS micro-vibration mirror array mechanism 2, each MEMS micro-vibration mirror 21 in the MEMS micro-vibration mirror array mechanism 2 can independently control the reflection angle, the imaging lens 3 has a positive focal length, the parallel lights are reflected into the parallel lights through the MEMS micro-vibration mirror array mechanism 2 and form a real image 4 in the air after being converged through the imaging lens 3, and the user can view the complete real image 4 as long as the user is in an area covered by an eyebox 5.

The MEMS micro-mirror array mechanism 2 is formed by splicing a plurality of MEMS micro-mirrors 21 in a rectangular array, and the arrangement of the MEMS micro-mirrors 21 is not limited to the form shown in fig. 5, nor is the size of a single MEMS unit, and is specifically determined according to the refresh frequency of the MEMS micro-mirrors 21 and the angular deflection precision.

The imaging lens 3 can adopt a single Fresnel lens or a Fresnel lens group, and the size and the weight of the whole device can be further reduced by utilizing the light and thin characteristics of the Fresnel lens. The MEMS micro-galvanometer array mechanism 2 modulates incident parallel light into parallel light with different angles, and the parallel light with one angle can finally form a real image point in the air after passing through the imaging lens 3; then, the MEMS array can reconstruct a picture in the air by modulating the incident parallel light into different angles.

If only a monochromatic image is required to be displayed, the light source 1 emits a light beam of a single color, and if a color image is to be displayed, the light source 1 may use R, G, B three-color mixed light beams.

The larger the normal included angle between the light source 1 and the surface of the MEMS micro-oscillating mirror array mechanism 2 is, the smaller the distance between the imaging lens 3 and the MEMS micro-oscillating mirror array mechanism 2 can be, which can effectively shorten the volume of the system, but the larger the normal included angle is, the smaller the requirement on the size of the MEMS micro-oscillating mirror 21 is, the more the number of the MEMS micro-oscillating mirrors 21 is required, so that the proper normal included angle between the light source 1 and the MEMS micro-oscillating mirror array mechanism 2 is to be selected according to the actual cost.

The light source 1 of the parallel coarse light beams is matched with the MEMS micro-vibration mirror array mechanism 2, so that large-size eye box 5 range viewing can be realized without a screen, and the space occupied by the MEMS can be further reduced by adopting the MEMS micro-vibration mirror array mechanism 2 relative to a single MEMS, so that the purpose of small volume and large view field is realized.

Example two:

as shown in fig. 6, the difference from the first embodiment is that: a beam splitter 6 is additionally arranged between a light source 1 and the MEMS micro-vibration mirror array mechanism 2, the surface of the beam splitter 6 is provided with a coating film, so that light irradiated on the beam splitter 6 is transmitted by 50% and reflected by 50% at a first incident surface, and an anti-reflection film is also coated on a second incident surface of the light on the beam splitter 6 to ensure that the light is transmitted as far as possible. The first incident surface of the beam splitter 6 is transmitted by 50% and reflected by 50%, and the utilization rate of light is the highest.

The coarse light beams emitted by the light source 1 irradiate the beam splitter 6 and are reflected to the MEMS micro-vibration mirror array mechanism 2 by the beam splitter 6, the reflection angle of each MEMS micro-vibration mirror 21 in the MEMS micro-vibration mirror array mechanism 2 can be independently adjusted to form a plurality of beams of parallel light, the parallel light beams pass through the beam splitter 6 and are converged through the imaging lens 3 to form a real image 4, and the user can view the complete real image 4 as long as the user is in an area covered by the eye box 5.

Example three:

as shown in fig. 7, the difference from the first embodiment is that: two beam splitters 6 are added between the light source 1 and the MEMS micro-vibration mirror array mechanism 2, after the two beam splitters 6 are added, the distance between the imaging lens 3 and the MEMS micro-vibration mirror array mechanism 2 can be reduced, the incident aperture of the light source 1 can also be reduced, and therefore the size of the system can be obviously reduced.

The two beam splitters 6 are arranged in parallel, a first beam splitter 61 is arranged close to the light source 1, a second beam splitter 62 is arranged far away from the light source 1, one part of light emitted by the light source 1 is reflected to the MEMS micro-vibration mirror array mechanism 2 through the first beam splitter 61, the other part of the light irradiates the second beam splitter 62 through the first beam splitter 61, one part of the light penetrates through the second beam splitter 62, the other part of the light is reflected to the MEMS micro-vibration mirror array mechanism 2 through the second beam splitter 62, the light reflected by the MEMS micro-vibration mirror array mechanism 2 penetrates through the first beam splitter 61 or/and the second beam splitter 62 and then is converged into a real image 4 through the imaging lens 3, and finally the complete real image 4 is observed by a user in the range of the eye box 5. The light transmittance of the first beam splitter 61 is 75%, and the reflectance is 25%; the second beam splitter 62 has a light transmittance of 50% and a reflectance of 50%, and maximizes efficiency and brightness uniformity.

After the beam splitter 6 is adopted in the second and third embodiments, there is no size limitation on the size of the single MEMS micro-galvanometer 21 in the MEMS micro-galvanometer array mechanism 2, and as long as the effective interval between the MEMS micro-galvanometer 21 is small enough to satisfy that no image loss occurs at different viewing positions, the number of MEMS will be small. Of course, three or even more pieces of beam splitter 6 can be used to further reduce the system size.

Example four

As shown in fig. 8, the difference from the first, second and third embodiments is that the imaging lens 3 has a negative focal length, so that the light beam reflected from the MEMS micro-mirror array mechanism 2 will diverge after passing through the imaging lens 3, and will form a virtual image 13 on the side of the imaging lens 3 located on the MEMS micro-mirror array mechanism 2. Imaging lens 3 can be a slice of concave lens, also can be the combination of concave lens and convex lens, as long as guarantee that whole imaging lens 3's focus is the negative focal length can to realize the HUD function.

In comparison with the conventional MEMS scheme, the above scheme eliminates the screen because of the coarse beam illumination, a large beam aperture that is suitable for human eyes can be formed; compared with the conventional negative refraction flat plate and similar HUD schemes, the system can remarkably reduce the volume of the system due to the adoption of the structure of the coarse light beam illumination and the beam splitter 6, namely the effects of smaller volume and larger field of view are realized.

The above description is only an embodiment of the present invention, but the technical features of the present invention are not limited thereto, and any changes or modifications within the technical field of the present invention by those skilled in the art are covered by the present invention.

Claims (10)

1. Vehicle-mounted imaging device based on MEMS array, its characterized in that: the method comprises the following steps:

light source: the device is used for emitting a plurality of parallel lights to form a rough light beam;

MEMS micro-galvanometer array mechanism: reflecting the coarse light beam emitted by the light source;

an imaging lens: the MEMS micro-vibration mirror array mechanism is provided with a positive focal length and is used for converging light beams reflected by the MEMS micro-vibration mirror array mechanism to form a real image; or the optical fiber has a negative focal length and is used for diverging the light beam reflected by the MEMS micro-vibration mirror array mechanism into a virtual image.

2. The MEMS array based vehicular imaging apparatus of claim 1 wherein: and at least one beam splitter is arranged on a light path between the light source and the MEMS micro-vibration mirror array mechanism.

3. The MEMS array based vehicular imaging apparatus of claim 2 wherein: and a beam splitter is further arranged on a light path between the light source and the MEMS micro-vibration mirror array mechanism, one part of the coarse light beam emitted by the light source is reflected to the MEMS micro-vibration mirror array mechanism through the beam splitter, and the other part of the coarse light beam penetrates through the beam splitter.

4. The MEMS array based vehicular imaging apparatus of claim 3 wherein: the light transmittance and the reflectivity of the beam splitter are respectively 50% and 50%.

5. The MEMS array based vehicular imaging apparatus of claim 2 wherein: two beam splitters which are arranged in parallel are further arranged on a light path between the light source and the MEMS micro-vibration mirror array mechanism and are respectively a first beam splitter and a second beam splitter, one part of a thick light beam emitted by the light source is reflected to the MEMS micro-vibration mirror array mechanism through the first beam splitter, the other part of the thick light beam irradiates the second beam splitter through the first beam splitter, one part of the thick light beam irradiating the second beam splitter is reflected to the MEMS micro-vibration mirror array mechanism, and the other part of the thick light beam irradiates the second beam splitter.

6. The MEMS array based vehicular imaging apparatus of claim 5 wherein: the light transmittance of the first beam splitter is 75%, and the reflectivity is 25%; the second beam splitter has a light transmittance of 50% and a reflectance of 50%.

7. The MEMS array based vehicular imaging apparatus of claim 1 wherein: the MEMS micro-vibration mirror array mechanism comprises a plurality of MEMS micro-vibration mirrors which are arranged according to a rectangular array.

8. The MEMS array based vehicular imaging apparatus of claim 1 wherein: the imaging lens has a positive focal length, and is a Fresnel lens or a Fresnel lens group.

9. The MEMS array based vehicular imaging apparatus of claim 1 wherein: the imaging lens has a negative focal length, and is a concave lens or a combination of a concave lens and one or more lenses.

10. The MEMS array based vehicular imaging apparatus of claim 1 wherein: the light beam emitted by the light source is a monochromatic light beam; alternatively, the light beam emitted by the light source is R, G, B three-color mixed light beam.

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