CN115097637B - Head-up display - Google Patents

Abstract

The invention relates to the technical field of head-up display, in particular to a head-up display, which comprises a projection light machine, a light source and a display unit, wherein the projection light machine is used for outputting projection light; the first polarizer is arranged on an output light path of the projection light machine; a PVG device disposed in an output optical path of the first polarizer; wherein the PVG device comprises a monolithic PVG element and/or PVG array; and the reflector is arranged on the output optical path of the PVG device and is used for reflecting and outputting the light output by the PVG device. Utilize the PVG device to realize the pupil expansion output to projection light in this application to realize the enlargeing to the projection picture of head-up display output to a certain extent, avoid leading to the problem of corresponding eye box undersize because of the problem that is limited to projection ray apparatus space size, be favorable to head-up display more effectively to show driving information, be favorable to head-up display's wide application.

Description

Head-up display

Technical Field

The invention relates to the technical field of head-up display, in particular to a head-up display.

Background

Head-up display (HUD for short) is often used in aircraft, vehicle driving, through projecting important driving information such as speed per hour, navigation direction and vehicle (or aircraft) state to the windshield on to the driver is when looking at the field of vision outside the windshield, also can see this important driving information when not lowering the Head, not turning around, for the driver in time knows driving information provides great convenience, be favorable to shortening the reaction time of driver when meetting emergency, improve driving safety and driving experience.

Although the head-up display has many advantages, if the eye box corresponding to the head-up display is too small, the driver can only receive and view the required driving information in a specific small area, and the difficulty of obtaining the driving information by the driver is increased, which obviously brings a certain limitation to the application of the head-up display. Therefore, how to solve the problem that the eye box of the head-up display is too small to cause the head-up display to be inconvenient to use is very important for the wide application of the head-up display.

Disclosure of Invention

An object of the present invention is to provide a head-up display which realizes an expanded pupil of a projection screen of the head-up display to thereby enlarge an eye box of the head-up display.

To solve the above technical problem, the present invention provides a head-up display including:

a projection light machine for outputting projection light;

the first polarizer is arranged on an output light path of the projection light machine;

a PVG device disposed in an output optical path of the first polarizer; wherein the PVG device comprises a monolithic PVG element and/or PVG array;

the reflector is arranged on an output light path of the PVG device and is used for reflecting and outputting light output by the PVG device;

when the PVG device comprises the monolithic PVG element, the first polarizer is used for modulating the projection light output by the projection light machine into polarized light and outputting the polarized light to the monolithic PVG element; the single-chip PVG element is used for partially diffracting the polarized light and outputting one path of left-handed circularly polarized light, one path of right-handed circularly polarized light and one path of transmission light with different directions to the reflector;

when the PVG device is a PVG array, the first polarizer is configured to modulate the projection light into circularly polarized light and sequentially enter each PVG element in the PVG array, and each PVG element is configured to generate partial diffraction and partial transmission on the incident polarized light according to a corresponding set proportion to generate diffracted circularly polarized light output to the mirror and transmitted circularly polarized light output to a next adjacent PVG element; and the last PVG element of the PVG array is arranged to be fully diffracted incident to the mirror for incident transmitted circularly polarized light.

Optionally, the optical projection system further comprises a correction element arranged on an optical path between the optical projection machine and the reflecting mirror.

Optionally, the correcting element is any one of a flat mirror, a reflective volume holographic grating, and a free-form surface mirror.

Optionally, when the PVG device comprises the monolithic PVG element; an optical waveguide for performing one-dimensional pupil expansion on the projection light output by the projection light machine is also arranged between the projection light machine and the first polarizer;

and the projection light output by the projection light machine enters the first polarizer after passing through the optical waveguide one-dimensional pupil expansion.

Optionally, a correction element is disposed between the monolithic PVG element and the mirror, and the correction element is configured to reflect or diffract light output by the monolithic PVG element to the mirror. .

Optionally, when the PVG device is a PVG array including a plurality of PVG elements, a side of the PVG array facing away from the projection light engine is provided with a correction element; and the correcting element is a reflecting element or a diffracting element;

a wave plate is arranged between the PVG array and the correcting element;

each PVG element is used for sequentially transmitting the circular polarization output by the first polarizer, enabling the circular polarization to enter the correcting element through the wave plate, and sequentially performing partial diffraction on the circular polarization output by the wave plate after the circular polarization is diffracted or reflected by the correcting element and outputting the circular polarization to the reflecting mirror.

Optionally, when the PVG device is a PVG array, a side of the PVG array facing away from the first polarizer is provided with a correction element; and the correcting element is a reflecting element or a diffracting element; the correcting element is used for diffracting or reflecting the projection light rays output by the projection light machine and transmitted by the first polarizer and the PVG array in sequence to the PVG array;

the PVG optical fiber correction device further comprises a plurality of second polarizers which are sequentially arranged on an output optical path of the correction element, and each second polarizer is correspondingly arranged on an input optical path of one PVG element; the second polarizer is used for modulating light rays which are output by the correcting element and sequentially enter the PVG elements corresponding to the second polarizer into elliptically polarized light, so that the corresponding PVG elements can perform partial diffraction and partial transmission on the elliptically polarized light, and the polarization states of the elliptically polarized light formed by modulation of the second polarizers are not identical.

Optionally, when the PVG device is a PVG array, the PVG array includes a first PVG array and a second PVG array;

wherein the first PVG array comprises a plurality of first PVG elements arranged in sequence on an output optical path of the first polarizer; the second PVG array comprises a plurality of second PVG elements which are sequentially arranged on the diffraction output optical path of the first PVG array; the straight line where the first PVG array is located and the straight line where the second PVG array is located are not coincident or parallel;

each of the first PVG elements is configured to diffract the circularly polarized light output by the first polarizer to output diffracted light, and the diffracted light passes through each of the second PVG elements in sequence, and is partially diffracted and partially transmitted by each of the second PVG elements, and the formed diffracted light is incident on the mirror.

Optionally, a first wave plate and a first correction element are sequentially arranged on one side of the first PVG array, which is away from the projection light engine; and a second wave plate and a second correcting element are sequentially arranged on one side of the second PVG array, which is far away from the first PVG array.

Optionally, when the PVG device is a PVG array, each PVG element of the PVG array is respectively configured to diffract the polarized light component of the other wavelength band to transmit to the circularly polarized light component of the specific wavelength band in the incident polarized light, and the wavelength range of the diffractable circularly polarized light corresponding to each PVG element is different.

Optionally, when the PVG device is a PVG array, an optical waveguide for performing one-dimensional pupil expansion on the projection light output by the projection light engine is further disposed between the projection light engine and the first polarizer;

and the projection light output by the projection light machine enters the first polarizer after passing through the optical waveguide one-dimensional pupil expansion.

The invention provides a head-up display, which comprises a projection light machine for outputting projection light; the first polarizer is arranged on an output light path of the projection light machine; a PVG device disposed in an output optical path of the first polarizer; wherein the PVG device comprises a monolithic PVG element and/or PVG array; the reflector is arranged on an output light path of the PVG device and is used for reflecting and outputting light output by the PVG device; when the PVG device comprises a single-chip PVG element, the first polarizer is used for modulating the projection light output by the projection light machine into polarized light and outputting the polarized light to the single-chip PVG element; the single-chip PVG element is used for partially diffracting the polarized light and outputting one path of left-handed circularly polarized light, one path of right-handed circularly polarized light and one path of transmission light with different directions to the reflector; when the PVG device is a PVG array, the first polarizer is used for modulating projection light into circularly polarized light and sequentially enabling the circularly polarized light to enter each PVG element in the PVG array, and each PVG element is used for generating partial diffraction and partial transmission on the circularly polarized light according to a corresponding set proportion to generate diffracted circularly polarized light output to the reflector and transmitted circularly polarized light output to the next adjacent PVG element; and the last PVG element of the PVG array is used to diffract incident transmitted circularly polarized light completely into the mirror.

The head-up display in the application is provided with the PVG device on an output light path of a projection light machine, and for a single PVG element, the characteristics that the single PVG element can simultaneously transmit and diffract incident polarized light and can generate diffracted light rays in two different directions are utilized to realize the expanded output of the same projected light ray to a plurality of different directions simultaneously, and the same projected light ray is reflected by a reflector and output to human eyes, so that the pupil expansion of the projected light ray is realized; for the PVG array, each PVG element transmits and diffracts part of the projection light in sequence, so that the projection light can be diffracted to the reflector in sequence through different PVG elements and then is reflected and output, and the expanded pupil output of the projection light can be realized.

From this, utilize PVG device to realize the pupil expansion output to projection light in this application to realize the pupil expansion to the projection light of head-up display output to a certain extent, make projection light's divergence angle increase, thereby avoid leading to the less and then leading to the less problem of head-up display corresponding eye box because of being limited by projection light machine spatial dimension's problem leads to projection light divergence angle, promote the convenience that the driver watched driving information, be favorable to head-up display's wide application.

Drawings

In order to more clearly illustrate the embodiments or technical solutions of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

FIG. 1 is a schematic diagram of a diffraction optical path of a reflective PVG provided in an embodiment of the present application;

FIG. 2 is a schematic diagram of a diffraction optical path of a transmissive PVG provided in an embodiment of the present application;

FIG. 3 is a schematic diagram of a first optical path structure of a head-up display according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of a second optical path structure of a head-up display according to an embodiment of the present application;

FIG. 5 is a schematic diagram of a third optical path structure of a head-up display according to an embodiment of the present application;

FIG. 6 is a schematic diagram illustrating a fourth optical path structure of a head-up display according to an embodiment of the present disclosure;

FIG. 7 is a schematic diagram illustrating a fifth optical path structure of a head-up display according to an embodiment of the present disclosure;

fig. 8 is a schematic diagram illustrating a sixth optical path structure of a head-up display according to an embodiment of the present disclosure.

Detailed Description

When the head-up display is used for airplane driving or automobile driving, a picture of driving information or the like displayed by the head-up display is mainly formed by imaging a reflected light beam projected onto a windshield through a projection light beam output by a projection light machine inside the head-up display by an optical system. It can be understood that when the divergence angle of the projection light output by the projection light machine reflected to human eyes through the windshield is small, the human eyes can receive the reflected projection light only in a small area, and the corresponding eye box of the driver is small; that is to say, when the driver obtains the virtual projection image displaying the driving information, the driver can only see the virtual projection image if the eyes of the driver are in a fixed small area, and in the dynamic driving process of the driver, it is obviously difficult to keep the eyes in a small eye box state, but the attention of the driver can be influenced to a certain extent, and potential safety hazards are generated. As a result, the screen size output from the head-up display is too small, which is not favorable for effective display of the driving information.

In order to output a large-sized projection image in the head-up display, more geometric optical elements, such as various optical lenses, need to be added in the projector to enlarge the output projection image. However, the size of the installation space of the projector is limited by the installation space of the head-up display, and the size of the projection picture output by the projector cannot be very large, which limits the size of the projection picture to a certain extent.

Therefore, the technical scheme that the pupil expanding of the projection light output by the head-up display can be achieved, the eye box corresponding to the head-up display system is enlarged, and the head-up display system is widely applied. In order that those skilled in the art will better understand the disclosure, reference will now be made in detail to the embodiments of the disclosure as illustrated in the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

For the understanding of the following embodiments, the characteristics of the PVG, which is called Polarization Volume grading, i.e. a polarizer holographic Grating, will be briefly described below. PVGs can be divided into reflective PVGs and transmissive PVGs; referring to fig. 1 and fig. 2, fig. 1 is a schematic diagram of a diffraction optical path of a reflective PVG provided in an embodiment of the present application; fig. 2 is a schematic diagram of a diffraction optical path of the transmissive PVG according to an embodiment of the present disclosure.

When polarized light is incident on the PVG, the polarized light can be partially diffracted and partially transmitted, forming one path of diffracted circularly polarized light and one path of transmitted circularly polarized light. According to the vector synthesis principle of polarized light, the polarized light entering the PVG can be linearly polarized light, circularly polarized light or elliptically polarized light as long as the polarized light can be obtained by vector synthesis of two circularly polarized lights; when the PVG is a reflective PVG, the diffracted circular polarized light is a reflective diffraction output; and when the PVG is transmission type PVG, the diffraction circular polarized light is transmission type diffraction output.

In addition, when linearly polarized light enters the PVG at a specific angle, the linearly polarized light can also generate another different diffraction and transmission from the above-mentioned diffraction and transmission, and two paths of diffraction light and one path of transmission light can be output after the diffraction and transmission, wherein the two paths of diffraction light are two paths of circularly polarized light with different polarization rotation directions and different output directions, and the output direction of the transmission light is also different from the output direction of the two paths of circularly polarized light, so that the linearly polarized light can output light in three different directions after passing through the PVG in the diffraction and transmission process.

According to the above PVG characteristics, when the PVG diffracts the incident polarized light, the ratio of the diffracted light to the transmitted light can be adjusted and set through the set incident angle, polarization state and thickness of the PVG, and even the diffraction efficiency of the polarized light which is incident at a certain specific angle and satisfies the specific polarization state can be close to or even reach 100%.

Based on the above discussion, in the head-up display in the present application, the PVG device can be used to implement the pupil expansion of the projection light output by the projection light machine, so as to implement the display of the large-size image of the head-up display.

Refer to fig. 3, 4, 5, 6, 7, 8; FIG. 3 is a schematic diagram of a first optical path structure of a head-up display according to an embodiment of the present disclosure; FIG. 4 is a schematic diagram of a second optical path structure of a head-up display according to an embodiment of the present application; FIG. 5 is a schematic diagram of a third optical path structure of a head-up display according to an embodiment of the present application; FIG. 6 is a fourth optical path schematic diagram of a head-up display according to an embodiment of the present disclosure; FIG. 7 is a schematic diagram illustrating a fifth optical path structure of a head-up display according to an embodiment of the present disclosure; fig. 8 is a schematic diagram illustrating a sixth optical path structure of a head-up display according to an embodiment of the present disclosure.

It should be noted that, in the optical paths referred to in the above drawings, only straight lines or lines with arrows substantially illustrate the transmission paths of light rays, and the exact correspondence relationship that should be satisfied between the incident angle, the reflection angle, and the diffraction angle in diffraction, reflection, and transmission is not strictly observed between the incident light rays and the outgoing light rays. And are simply shown in the various figures as a plurality of optical elements parallel to one another, such as between a plurality of PVG elements in a PVG array, and not necessarily parallel to one another.

In particular embodiments of the present application, the optical path of the heads-up display may substantially comprise:

a projection light machine 1 for outputting projection light;

the first polarizer 2 is arranged on an output light path of the projection light machine;

a PVG device disposed on an output optical path of the first polarizer 2;

and the reflecting mirror 4 is arranged on the output optical path of the PVG device and is used for reflecting and outputting the light output by the PVG device.

It should be noted that the optical projection engine 1 in this embodiment may specifically adopt an optical engine formed by any one type of light source, such as an LED, an OLED, a Mini-LED, a Micro-LED, and an L-COS, and is an image source for providing a head-up display with data images, such as driving information.

In addition, the first polarizer 2 in this embodiment may be a device capable of modulating the projection light output by the projection light engine 1 into a specific polarized light, specifically into a specific linearly polarized light or an elliptically circularly polarized light, depending on the type of the PVG device.

Further, with the reflector 4 in the present embodiment, which is essentially the windshield; the windshield can be provided with a reflection increasing and reflection reducing coating to increase the reflectivity of light output by the PVG device and increase the transmissivity of natural light; the holographic film can be pasted on the windshield, so that the projection light can be efficiently reflected and diffracted into human eyes, and meanwhile, the high-efficiency transmission of natural light can be guaranteed.

As with the different operating characteristics of PVGs described above, PVG devices can exist in a variety of different implementations.

In the embodiment where the PVG device is a monolithic PVG element 30, the PVG device can be implemented by utilizing the characteristic that the monolithic PVG element 30 can diffract linearly polarized light to generate two different circularly polarized lights and one transmitted light.

In the embodiment shown in fig. 3, the first polarizer 2 may be a wave plate, or may be another type of polarizer, as long as the projection light output by the projector 1 can be modulated to form linearly polarized light meeting the diffraction requirement of the monolithic PVG element 30, at this time, the monolithic PVG element 30 is configured to partially diffract and partially transmit the linearly polarized light, and output one path of left-handed circularly polarized light, one path of right-handed circularly polarized light, and one path of transmission light to the mirror 4, where the directions of the left-handed circularly polarized light, the right-handed circularly polarized light, and the transmission light are different from each other.

It can be understood that, in the embodiment of the present application, the monolithic PVG element 30 partially diffracts the linearly polarized light to form two paths of diffracted light, that is, one path of left-handed circularly polarized light and one path of right-handed circularly polarized light, and also partially transmits the linearly polarized light to form one path of transmitted light. The output direction of the transmitted light is the same as the direction of the linearly polarized light incident to the monolithic PVG element 31, and the left circularly polarized light and the right circularly polarized light are respectively output in opposite directions deviating from the transmitted light by a certain angle, so that the linearly polarized light is divided into three paths of light output in different directions, the expansion of the divergence angle of the linearly polarized light is realized, the three paths of light output in different directions are reflected by the reflector 4 and output to human eyes, and the pupil expansion of a projection picture output by the head-up display can be realized to a certain extent.

In addition, in the embodiment shown in fig. 3, only one monolithic PVG element 30 is included, and left-circularly polarized light, right-circularly polarized light and transmitted light output by the monolithic PVG element 30 in a single direction are located in the same plane, that is, the monolithic PVG element 30 can only realize pupil expansion of the projected light in a plane parallel to the planes of the left-circularly polarized light, the right-circularly polarized light and the transmitted light. In the embodiment that only one-dimensional pupil expansion is required for the projection image output by the projection optical engine 1, the embodiment similar to that shown in fig. 3 can be used to realize clear display of the projection image.

However, in practical applications, most of the projection light machine 1 projects and displays two-dimensional images, and therefore, a specific embodiment of the projection light machine 1 needs to perform two-dimensional pupil expansion to clearly display a projection picture. To this end, in an alternative embodiment of the present application, two pieces of the monolithic PVG element 30 may be provided; take the example that the PVG device includes a first monolithic PVG element and a second monolithic PVG element; accordingly, the first polarizer 2 includes a first polarizer one and a first polarizer two;

the optical path structure of the head-up display may include:

the projection optical machine 1, a first polarizer I arranged on an output light path of the projection optical machine 1, a first monolithic PVG element arranged on the output light path of the first polarizer, a second polarizer II arranged on the output light path of the first monolithic PVG element, a second monolithic PVG element arranged on the output light path of the second polarizer, and a mirror arranged on the output light path of the second monolithic PVG element; wherein the first monolithic PVG element and the second monolithic PVG element do not have mutually parallel pupil expanding directions for incident linearly polarized light rays.

When projection light output by the projection light machine 1 passes through the first polarizer, the projection light can be modulated into linear polarized light, and the linear polarized light is incident on the first single-chip PVG element to be output to form three paths of light in different directions, so that one-dimensional pupil expansion of the projection light is realized, the three paths of light in different directions pass through the second polarizer, the linear polarized light is re-modulated to form linear polarized light and is incident on the second single-chip PVG element, the three paths of polarized light in different directions respectively realize pupil expansion, and the pupil expansion direction of the first single-chip PVG element are not parallel to each other and can be perpendicular to each other, so that two-dimensional pupil expansion of the projection light can be realized, namely two-dimensional pupil expansion output of the head-up display is realized, and the size of a projection display picture is expanded.

Of course, in practical applications, other optical elements with a pupil expanding function and the single PVG element 30 may be used to implement a two-dimensional pupil expansion of the projection image of the head-up display. Referring to fig. 4, in an alternative embodiment of the present application, on the basis that the PVG device includes a monolithic PVG element 30, an optical waveguide for performing one-dimensional pupil expansion on the projection light output by the projection light engine is further disposed between the projection light engine 1 and the first polarizer 2; the projection light output by the projection light machine 1 passes through the optical waveguide one-dimensional pupil expanding and then enters the first polarizer 2.

Referring to fig. 4, the optical waveguide includes a waveguide member 6, an incoupling grating 61 disposed on the waveguide member 6, and an outcoupling grating 62 disposed on the waveguide member 6. The projection light output by the projection light machine 1 is incident on the waveguide element 6, because the coupling-in grating 61 couples the projection light into the waveguide element 6 and transmits the projection light in a total reflection manner, and because the surface of the waveguide element 6 is also provided with the coupling-out grating 62, in the process of total reflection transmission of the projection light in the waveguide element 6, partial diffraction and partial reflection can be generated every time the projection light passes through the interface between the waveguide element 6 and the coupling-out grating 62, wherein the diffraction light can be output by the coupling-out waveguide element 6, and the reflection light continuously transmits forwards in a total reflection manner until the next time the projection light reaches the interface between the waveguide element 6 and the coupling-out grating 62 again, partial diffraction and partial reflection are generated again, so that one path of diffraction light is output again, so that the multi-path diffraction light can be output from different positions of the waveguide element 6 repeatedly, and the one-dimensional pupil expansion of the projection light in the total reflection transmission direction in the waveguide element 6 is realized.

The projection light output by the projection light machine 1 passes through the optical waveguide one-dimensional pupil expanding and is output to the first polarizer 2, and then the projection light can be modulated to form linearly polarized light, and the two-dimensional pupil expanding of the projection light is realized through the single PVG element 30. It is understood that the pupil expanding direction of the single PVG element 30 for the projection light and the pupil expanding direction of the optical waveguide for the projection light should not be parallel and may be perpendicular to each other.

For the incoupling grating 61 in the optical waveguide, a polarizer holographic grating, a surface relief grating, or a volume holographic grating may be used; for the coupling grating 62 in the optical waveguide, a volume holographic grating may be used, or PVG may be used, but a polarization device needs to be additionally disposed between the optical waveguide and the projection optical engine 1, or other embodiments may be used, which are not listed in this application. The incoupling grating 61 and the outcoupling grating 62 may be transmission gratings or reflection gratings, and most preferably, in the present embodiment, the incoupling grating 61 and the outcoupling grating 62 are located on the same side of the waveguide 6, and one of them is a transmission grating and the other is a reflection grating.

Further, it is considered that the single PVG element 30 inevitably distorts the projection screen formed by the projection light in the process of realizing the pupil expansion of the projection light. For this purpose, in an alternative embodiment of the present application, a correction element 5 may be further disposed in the optical path between the projection light engine 1 and the mirror 4, and the correction element 5 is mainly used for correcting the projection light. Different types of optical elements can be used for the correction element 5 depending on the position in which it is arranged.

In an alternative embodiment of the present application, the correcting element 5 may be disposed between the monolithic PVG element 30 and the mirror 4, and the correcting element 5 may be a reflective element or a diffractive element; the optical path structure of the head-up display may include a projection light 1, a first polarizer 2, a monolithic PVG element 30, a correction element 5, and a mirror 4 in this order.

Projection light output by the projection light machine 1 forms circularly polarized light through the first polarizer 2, the circularly polarized light enters the single-chip PVG element 30 and then enters the correcting element 5 from the single-chip PVG element 30, the light entering the correcting element 5 is reflected or diffracted, image distortion is corrected and then output to the reflector 4, and finally the corrected light is reflected and output to human eyes through the reflector 4.

In the present embodiment, the correcting element 5 may be a mirror or a diffractive element, and may be any optical element of a flat mirror combination element, a reflective volume holographic grating, and one or more free-form surface mirrors, for example, which is not limited in this application. It is understood that the present application does not exclude the embodiment in which the correcting element 5 is an optical lens, and for example, the correcting element may be disposed between the projector 1 and the first polarizer 2, and the specific operation and principle thereof may refer to the principle of correcting distortion of an image, which is conventional in the optical field, and therefore, the present application does not describe in detail.

In an alternative embodiment of expanding the projection light output by the projection light engine in two dimensions, the optical path structure of the head-up display may include: a projection light machine 1, an optical waveguide, a first polarizer 2, a monolithic PVG element 30, a correction element 5 and a mirror 4.

The light transmission path and the optical path elements in this embodiment are similar to those in the above embodiments, and are not described again in this embodiment.

In another optional embodiment of the present application, the two-dimensional pupil expansion of the projection light output by the projection light engine may include: the projection optical machine 1, a first polarizer I, a first monolithic PVG element, a correction element I, a first polarizer II, a second monolithic PVG element, a correction element II and a reflecting mirror 4.

In this embodiment, the projection light output by the projection light engine sequentially passes through the first polarizer and the first monolithic PVG element, outputs diffracted light to be incident on the first correcting element, is diffracted, reflected or transmitted by the first correcting element, is incident on the second polarizer, is incident on the second correcting element by the second polarizer, and is finally output by the second correcting element, which is incident on the mirror. This embodiment is equivalent to having two sets of optical path structures composed of the first polarizer 20, the single PVG element 30, and the correcting element 5, and the working manner and principle of each optical element in each set of optical path structure are the same as those of the embodiment shown in fig. 3, and are not described again here.

Based on the above discussion, embodiments of the PVG device including the PVG array 31 will be described in further detail below.

In an alternative embodiment of the present application, referring to fig. 5, the optical path structure of the head-up display may include a projector light machine 1, a first polarizer 2, a PVG array 31, and a mirror 4.

The first polarizer 2 is used for modulating the projection light into polarized light and sequentially entering each PVG element in the PVG array 31; each PVG element is used for generating diffraction circular polarized light output to the reflecting mirror and transmission circular polarized light output to the next adjacent PVG element according to the corresponding set proportion of the incident polarized light and partial diffraction and partial transmission; and the last PVG element in the PVG array 31 is used to diffract incident transmitted circularly polarized light completely to the mirror 4.

In this embodiment, the projection optical engine and the reflection mirror are both the same as the projection optical engine 1 in any of the above embodiments, and are not described herein again. Unlike the embodiment in which the PVG device is a monolithic PVG element 30, the first polarizer 2 in this embodiment is a device for modulating the projection light output by the projection light engine 1 into polarized light that meets the requirements of the PVG element.

Taking the embodiment shown in fig. 5 as an example, the PVG array includes three PVG elements, i.e., a first PVG element 311, a second PVG element 312, and a third PVG element 313. And each PVG element is a transmission type PVG element which can generate partial diffraction transmission to the right-handed circularly polarized light. After the projection light output by the projection light machine 1 passes through the first polarizer 2, the projection light may be modulated by the first polarizer 2 to form right-handed circularly polarized light, the right-handed circularly polarized light is firstly incident on the PVG element one 311, the PVG element one 311 partially diffracts and partially transmits the right-handed circularly polarized light, the diffracted light formed by partial diffraction is incident on the mirror and output to the human eye by the mirror 4, and the transmitted light formed by partial transmission is incident on the PVG element two 312, obviously, the transmitted light is also the right-handed circularly polarized light, and can be partially reflected and partially transmitted again by the PVG element two 312, the formed diffracted light is also incident on the mirror 4 and reflected to the human eye, and the formed transmitted light is incident on the PVG element three 313, because the PVG element three 313 is the last PVG element in the optical path direction in the PVG array 31, therefore, the diffraction efficiency of the PVG element three 313 is set to one hundred, and the incident transmitted light is totally diffracted.

Referring to fig. 5, it can be seen that, each PVG element in the PVG array 31 sequentially diffracts and outputs the projection light onto the reflector 4, so as to realize the diffusion output of the projection light onto the reflector 4, and the diffused projection light is reflected to the human eyes through the reflector 4, so as to form an expanded projection screen, that is, to realize the expanded pupil of the projection screen output by the head-up display.

It can be understood that, in the PVG array in the present embodiment, the last PVG element in the optical path direction, i.e. PVG element three 313, diffracts the incident circularly polarized light completely, and the diffraction efficiency reaches one hundred percent, and is not absolutely complete diffraction, but is close to complete diffraction, or it can be considered that the diffraction efficiency reaches one hundred percent approximately, and the undiffracted light energy can be ignored.

In addition, for each PVG element in the PVG array 31, the proportion of partial diffraction and partial transmission of the incident polarized light can be set based on actual needs, and specifically can be adjusted and set by setting the thickness size, polarization state, incident angle of incident light and the like of the PVG element; when the polarized light incident to the PVG element is circularly polarized light, the ratio of diffraction to transmission of the circularly polarized light is mainly adjusted by setting the thickness of the PVG element, and similar situations in subsequent embodiments are not repeated.

For example, in the embodiment shown in fig. 5 including three PVG elements, the ratio of light energy diffracted and transmitted by the PVG element one 311 for circularly polarized incident light can be set to 1; the ratio of diffraction to transmission of the light output by the PVG element one 311 by the PVG element two 312 is 1; finally, the third 313 PVG element diffracts the incident light completely; therefore, for the first PVG element 311, the second PVG element 312, and the third PVG element 313, the ratio of diffracted light energy output is 1. When the three PVG elements output diffracted light to different positions on the reflector 4 to form a projection picture, the brightness uniformity of the whole projection picture can be ensured.

It is understood that the PVG array including only three PVG elements is only an alternative embodiment of the present application, and in practical applications, a PVG array 31 including more PVG elements may be provided based on actual needs and requirements of an installation environment, and the operation manner and principle thereof are similar to those of the embodiment shown in fig. 5.

In addition, in the above embodiment, the example that each PVG element in the PVG array 31 is a transmissive PVG which can partially diffract and partially transmit right-handed circularly polarized light is taken as an example, and in practical application, an embodiment that each PVG element in the PVG array 31 can partially diffract and partially transmit left-handed circularly polarized light is not excluded, as long as the first polarizer 2 is correspondingly configured to modulate the light output by the projection light engine 1 into left-handed circularly polarized light. Furthermore, each PVG element in the PVG array 31 is not necessarily transmissive to circularly polarized light, but may also be reflective, which is not limited in this application.

In addition, in the process of expanding the pupil of the projection light output by the projector 1, the pupil can be expanded according to different color bands. In an optional embodiment of the present application, the optical path structure of the head-up display may include a projector light machine 1, a first polarizer 2, a PVG array 31, and a mirror 4; and each PVG element of the PVG array 31 is also sequentially disposed on the output optical path of the first polarizer; and each PVG element is used for diffracting the polarized light components of other wave bands and transmitting the polarized light components of the other wave bands to the circularly polarized light components of a specific wave band in incident polarized light, and the wave band ranges of the diffractible circularly polarized light corresponding to the PVG elements are different.

Similarly, in the present embodiment, the optical path configuration shown in fig. 5 may be used as a reference, and for convenience of simplification of description, the PVG element one 311, the PVG element two 312, and the PVG element three 313 in the PVG array shown in fig. 5 may be respectively configured to correspond to an R-PVG element that can diffract circularly polarized light in a red wavelength band, a G-PVG element that diffracts circularly polarized light in a green wavelength band, and a B-PVG element that diffracts circularly polarized light in a blue wavelength band.

The projection light output by the projection light machine 1 is modulated by the first polarizer 2 to form polarized light synthesized by red waveband circularly polarized light, green waveband circularly polarized light and blue waveband circularly polarized light, when the polarized light passes through the PVG element one 311, the red waveband circularly polarized light is totally diffracted and incident to the reflector 4, the green waveband circularly polarized light and the blue waveband circularly polarized light are transmitted and incident to the PVG element two 312, the PVG element two 312 is utilized to totally diffract the green waveband circularly polarized light and incident to the reflector 4, the blue waveband circularly polarized light is transmitted and incident to the PVG element three 313, and the light is totally diffracted and output to the reflector 4 through the PVG element 313.

Therefore, when the circularly polarized light in each of the three different color waveband ranges is diffracted and output to the reflector and is output by the reflector to form a projection picture, the imaging areas with different diffraction are mutually dispersed, so that the diffusion among different colors of light in the projection light can be realized, and the effect of displaying the imaging pictures with different colors in different areas is formed. In practical application, different information or pictures can be projected and displayed by using projection lights with different colors, for example, driving speed information is information that a driver needs to pay more attention to, red light can be used for projection and display, the remaining oil amount is important information next to the driving speed, green light can be used for projection and display, and the current environmental temperature and other secondary information can be sampled for projection and display by using blue light.

It can be understood that, in practical applications, the division of different wavelength bands of the projection light is not limited to the division of three primary colors of red, green and blue, for example, a yellow wavelength band, a purple wavelength band, an orange wavelength band, etc., that is, in the PVG array 31, the wavelength band range of the diffractible circularly polarized light corresponding to each PVG element is not limited to three wavelength bands of red, green and blue, but may also be other different wavelength bands, which is not limited in this application.

In addition, considering that a separate pupil expansion may be required for each of the projection light beams in the wavelength range, a plurality of PVG elements capable of diffracting circularly polarized light may be provided for each or a certain wavelength range, and the diffraction efficiencies of the PVG elements for circularly polarized light in the diffractible wavelength range may be different from each other.

For example, three R-PVG elements, three G-PVG elements, and a B-PVG element may be sequentially disposed on the output light path of the first polarizer 2, so that the red-band circularly polarized light component in the polarized light output by the first polarizer may sequentially pass through the first two R-PVG elements to be partially diffracted and partially transmitted, and completely diffracted by the third R-PVG element, while the green-band circularly polarized light component sequentially passes through the three R-PVG elements to be transmitted, then passes through the three G-PVG elements to be partially diffracted and partially projected, and completely diffracts by the last G-PVG element; and the circularly polarized light component of the blue waveband is transmitted by the three R-PVG elements and the three G-PVG elements in sequence and finally enters the B-PVG element for complete diffraction.

Therefore, the regional display of the imaging pictures of the light rays with different color wave bands and the pupil expansion of the light rays with each color wave band can be realized.

It is considered that the PVG array 31 and various other optical elements inevitably cause distortion of a projection picture during transmission of projection light. Therefore, in this embodiment, a correction element may be further added, and taking the correction element as a reflection element or a diffraction element as an example, the correction element 5 is disposed on the side of the PVG array 31 facing away from the projection optical machine 1; a wave plate 70 is also arranged between the PVG array 31 and the correcting element 5;

each PVG element is configured to sequentially transmit the circular polarization output by the first polarizer 2, and to enter the correction element through the wave plate 70, and sequentially perform partial diffraction on the circularly polarized light output by the wave plate 70 after diffraction or reflection by the correction element, and output the circularly polarized light to the mirror 4.

Referring to fig. 6, the projection light output by the projection light machine 1 passes through the first polarizer 2 to form left-handed polarized light, so that the left-handed polarized light can pass through each PVG element in the PVG array 31 completely and transmit through the wave plate 70, and then enters the correction element through the wave plate 70, and passes through the wave plate 70 again after being reflected or diffracted by the correction element 5, and the projection light passes through the wave plate 70 twice, and the projection light is also converted from left-handed circularly polarized light to right-handed circularly polarized light, and the right-handed circularly polarized light enters each PVG element in the PVG array 31 again, and first enters the PVG element three 313 to generate partial diffraction and partial transmission.

Set up projection ray machine 1 and correction element 5 respectively in this embodiment in the both sides of PVG array 31 for projection light passes through PVG array 31 twice, makes the light path that is used for rectifying projection light and is used for realizing the light path of projection light diffraction pupil coincide in space to a certain extent, and then makes whole light path structure more compact, is favorable to head-up display's lightweight.

In addition, the PVG array 31 in this embodiment may also transmit right-handed circularly polarized light, and diffraction of each PVG element on left-handed circularly polarized light may also be transmissive diffraction, which is not necessarily reflective diffraction as shown in fig. 6, and details are not described again in this embodiment.

In addition, in the embodiment shown in fig. 6, the conversion of the rotation direction of the circularly polarized light is realized by using a wave plate, but the wave plate is not necessarily used in practical application. In another alternative embodiment of the present application, the optical path structure of the head-up display may include:

a projection light machine 1, a first polarizer 2, a PVG array 31, a correction element 5, a plurality of second polarizers and a reflecting mirror;

the side of the PVG array 31 facing away from the first polarizer 2 is provided with a corrective element 5; and the correcting element 5 is a reflecting element or a diffractive element; the correcting element 5 is used for diffracting or reflecting the projection light output by the projection light machine 1 and transmitted by the first polarizer 2 and the PVG array 31 in sequence to the PVG array 31;

the device also comprises a plurality of second polarizers which are sequentially arranged on the output optical path of the correcting element 5, and each second polarizer is correspondingly arranged on the input optical path of one PVG element; the second polarizer is used for modulating light rays output by the correcting element 5 and sequentially incident to the PVG elements corresponding to the second polarizer into elliptically polarized light, so that the elliptically polarized light is partially diffracted and partially transmitted by the corresponding PVG elements.

It can be understood that, in this embodiment, the number of the second polarizers is the same as the number of the PVG elements in the PVG array 31, and one second polarizer is correspondingly disposed on the input optical path of each PVG element; taking the embodiment shown in fig. 7 as an example, the PVG array 31 is closest to the correction element by a third PVG element 313, a second polarizer third 73 corresponding to the third PVG element 313 is disposed between the third PVG element 313 and the correction element 5, a second polarizer second 72 corresponding to the second PVG element 312 is disposed between the second PVG element 312 and the third PVG element 313, and a second polarizer first 71 corresponding to the first PVG element 311 is disposed between the second PVG element 312 and the first PVG element 311; then, the projection light output by the projection light engine 1 sequentially passes through the first polarizer 2 and the PVG array 31 to be transmitted and incident to the correction element 5, and is reflected or diffracted by the correction element 5 to be incident to the PVG array 31 again, and before the light output from the correction element 5 sequentially enters each PVG element, obviously, the light may first pass through the second polarizer corresponding to each PVG element and is modulated into corresponding elliptically polarized light by the second polarizer; and the polarization states of the elliptically polarized light modulated and formed by the second polarizers are not identical.

Taking the embodiment shown in fig. 7 as an example, the circularly polarized light output by the correcting element 5 is firstly incident on the third polarizer 73 and modulated into elliptically polarized light, the third PVG element 313 partially diffracts the elliptically polarized light to form diffracted light to be incident on the mirror 4, and also partially transmits the diffracted light to be output to the second polarizer 72, and is modulated again to form elliptically polarized light of another polarization state to be incident on the second PVG element 312, the second PVG element 312 partially diffracts the elliptically polarized light to form diffracted light to be output to the mirror 4, and generates partially transmitted light to be incident on the first polarizer 71, and is modulated again by the first polarizer 71 to form elliptically polarized light of another polarization state, and is finally completely diffracted by the first PVG element 311.

It should be noted that, each second polarizer is required to modulate light that needs to be incident into the corresponding PVG element into elliptically polarized light with different polarization states, in order to adjust the proportion of diffraction and transmission of the incident light by each PVG element, for the elliptically polarized light with different polarization states, the directions of the maximum vibration vectors of the polarization are different, and further the diffraction efficiency that is finally input into the PVG element is also different, for the specific polarization state of the elliptically polarized light that is modulated and formed by each second polarizer, no specific limitation is made in this application, as long as the energy balance of the diffracted light of each PVG element is finally satisfied, or the application requirements are satisfied.

In addition, it can be understood that, in the process that the projection light output by the projection light engine 1 passes through the first polarizer 2 and then is transmitted through the PVG array 31, the projection light does not pass through each second polarizer, that is, when the projection light output by the first polarizer 2 is transmitted in the PVG array 31 and the light output by the correcting element 5 is incident on the PVG array 31, the projection light passes through different regions of each PVG element in the PVG array 31, and two light paths pass through the PVG array 31 and do not overlap with each other in space.

Based on the above discussion, the PVG array 31 mainly includes only one row of PVG elements to implement a one-bit extended pupil of the projection light in the above embodiment, and in practical applications, two rows of PVGs may also be used to implement a two-dimensional extended pupil of the projection light.

In an alternative embodiment of the present application, the PVG array 31 comprises a first PVG array 32 and a second PVG array 33;

wherein the first PVG array 32 includes a plurality of first PVG elements 321 sequentially disposed on an output optical path of the polarizer; the second PVG array 33 comprises a plurality of second PVG elements 331 arranged in series on the diffracted output optical path of the first PVG array 31; and the straight line of the first PVG array 32 and the straight line of the second PVG array 33 are not coincident or parallel;

the diffracted light, which is diffracted and output by each first PVG element 321 with respect to the output circularly polarized light of the polarizer, passes through each second PVG element 331 in turn, is partially diffracted and partially transmitted by each second PVG element 331, and the resulting diffracted light is incident on the mirror 4.

Similar to the embodiment shown in fig. 5, the PVG array in this embodiment is provided with two rows, the projection light is modulated by the first polarizer 2 to form circularly polarized light, and then enters the first PVG array 32, and the diffraction and transmission modes of the circularly polarized light by each first PVG element 321 in the first PVG array 32 are the same as those of the embodiment shown in fig. 5; what is different is that the diffracted light output by each first PVG array 32 is incident on the second PVG array 33, and the diffracted light output by each first PVG element 321 by each second PVG element 331 in the second PVG array 33 is also partially diffracted and partially transmitted, and the diffraction and transmission modes are completely the same as the transmission and diffraction modes of the circularly polarized light by the first PVG elements 321, so that the light diffracted and output by each second PVG element 331 is sequentially incident on the reflector 4, and thus the two-dimensional pupil expansion of the projected light is realized.

Still further, in an embodiment where the PVG device includes the first PVG array 32 and the second PVG array 33, a corrective element 5 may also be added in the optical path, the corrective element 5 may include a first corrective element 51 and a second corrective element 52, and referring to fig. 8, the specific optical path of the corresponding head-up display may include:

the first wave plate 701 and the first correcting element 51 are sequentially arranged on one side of the first PVG array 32, which is far away from the projection light engine 1; the second wave plate 702 and the second correcting element 52 are sequentially arranged on the side of the second PVG array 33, which faces away from the first PVG array 32.

Similar to the embodiment shown in fig. 6, in this embodiment, the projection light output by the projection light machine is modulated into circularly polarized light by the first polarizer 2, the circularly polarized light is transmitted by the first PVG array 32, enters the first correcting element 51 through the first wave plate 701, is reflected or diffracted by the first correcting element 51, and is output to the first PVG array 32 through the first wave plate 701 again, the rotation direction of the circularly polarized light after passing through the first wave plate 701 twice is changed, when the circularly polarized light enters the first PVG array 32, each first PVG element 321 may perform partial diffraction and partial transmission on the incident circularly polarized light in sequence, and the diffraction and transmission modes are the same as those of the embodiment shown in fig. 6, and are not repeated herein.

The diffracted light beams diffracted and output by each first PVG element 321 are incident on the second PVG array 33, the diffracted light beams also belong to circularly polarized light, the circularly polarized light is transmitted through the second PVG array 33, and is incident on the second correction element 52 through the second wave plate 702, so that the circularly polarized light is diffracted or reflected by the second correction element 52 and is output to the second PVG array 33 through the second wave plate 702 again, each second PVG element 331 in the second PVG array 33 also diffracts and partially transmits the incident circularly polarized light, the operation mode and principle thereof are the same as those of the first PVG element 321, details are not repeated here, and finally the light beams diffracted and output by the second PVG element 331 are incident on the reflector 4.

It is understood that, in the present embodiment, it is also contemplated to use a plurality of second polarizers instead of the first wave plate 701 and the second wave plate 702; and each PVG element in the first PVG array 32 and the second PVG array 33 can set a reasonable incident angle of light or a thickness of the PVG element according to actual needs, and finally diffraction and transmission of circularly polarized light according to a set proportion are achieved.

Of course, in practical application, it is not necessary to use two columns of PVG arrays, and in an alternative embodiment of the present application, the optical path structure of the head-up display may further include:

the projection optical system comprises a projection optical machine 1, an optical waveguide for performing one-dimensional pupil expansion on projection light output by the projection optical machine, a first polarizer 2, a PVG array 31 and a reflector 4.

Optionally, a wave plate 70 and a corrective element 5 may also be provided between the PVG array 31 and the mirror 4.

For the pupil expanding mode of the optical waveguide for the projection light, refer to the embodiment corresponding to fig. 4, and the pupil expanding mode of the PVG array 31 for the light output by the optical waveguide is the same as the pupil expanding mode of the PVG array 31 in any of the above embodiments, and for this reason, the details are not repeated in this embodiment.

In yet another alternative embodiment of the present application, the optical path structure of the head-up display may further include:

a projection optical machine 1, a first polarizer 2, a single-chip PVG element 30, a PVG array 31 and a reflecting mirror 4;

alternatively, a correction element 5 for correcting the distortion may be further added between the monolithic PVG element 30 and the PVG array 31, and between the PVG array 31 and the mirror 4.

The operation of the monolithic PVG element 30 and the PVG array 31 in this embodiment is similar to that in the above-described embodiment, and will not be described in detail here.

In summary, the head-up display provided by the present application fully utilizes the single PVG element in the PVG device to expand the pupil of the projection light to a certain extent, and the PVG array can finally realize the pupil expansion of the projection light output by the projection light machine by utilizing the characteristics of partial diffraction and partial transmission of the projection light by each PVG element, so as to expand the area and the field angle of the projection light output by the head-up display, thereby increasing the eye box of the corresponding driver, facilitating the improvement of the convenience for the driver to obtain the driving information carried by the projection picture of the head-up display, and further ensuring the driving safety when the head-up display is applied to projecting the driving information.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Furthermore, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include the inherent elements. Without further limitation, an element defined by the phrases "comprising one of 8230; \8230;" 8230; "does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element. In addition, parts of the above technical solutions provided in the embodiments of the present application, which are consistent with the implementation principles of corresponding technical solutions in the prior art, are not described in detail so as to avoid redundant description.

The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims (11)

1. A head-up display, comprising:

a projection light machine for outputting projection light;

the first polarizer is arranged on an output light path of the projection light machine;

a PVG device disposed in an output optical path of the first polarizer; wherein the PVG device comprises a monolithic PVG element and/or PVG array;

the reflector is arranged on an output light path of the PVG device and is used for reflecting and outputting light output by the PVG device;

when the PVG device comprises the monolithic PVG element, the first polarizer is used for modulating the projection light output by the projection light machine into polarized light and outputting the polarized light to the monolithic PVG element; the single-chip PVG element is used for partially diffracting the polarized light and outputting one path of left-handed circularly polarized light, one path of right-handed circularly polarized light and one path of transmission light with different directions to the reflector;

when the PVG device is a PVG array, the first polarizer is used for modulating the projection light into polarized light and sequentially entering each PVG element in the PVG array; each PVG element is used for generating partial diffraction and partial transmission of incident polarized light according to a corresponding set proportion to generate diffraction circular polarized light output to the reflecting mirror and transmission circular polarized light output to the next adjacent PVG element; and the last PVG element of the PVG array is arranged to be fully diffracted incident to the mirror for incident transmitted circularly polarized light.

2. A heads-up display as claimed in claim 1 further comprising a corrective element disposed in the optical path between the projector engine and the mirror.

3. A head-up display as claimed in claim 2, characterized in that the correction element is any one of an optical element of a flat mirror, a reflective volume holographic grating, a free-form mirror.

4. A heads-up display as claimed in any one of claims 1 to 3, wherein when the PVG device comprises the monolithic PVG element; an optical waveguide for performing one-dimensional pupil expansion on the projection light output by the projection optical machine is also arranged between the projection optical machine and the first polarizer;

and the projection light output by the projection light machine enters the first polarizer after passing through the optical waveguide one-dimensional pupil expanding.

5. A heads-up display as claimed in claim 4 wherein a corrective element is provided between the monolithic PVG element and the mirror for reflecting or diffracting light output by the monolithic PVG element to the mirror.

6. A head-up display as claimed in any one of claims 1 to 3, wherein when the PVG device is a PVG array comprising a plurality of PVG elements, a side of the PVG array facing away from the light projector is provided with a corrective element; and the correcting element is a reflecting element or a diffracting element;

a wave plate is arranged between the PVG array and the correcting element;

each PVG element is used for sequentially transmitting the circular polarization output by the first polarizer, enabling the circular polarization to enter the correcting element through the wave plate, and sequentially performing partial diffraction on the circularly polarized light output by the wave plate after the circularly polarized light is diffracted or reflected by the correcting element and outputting the circularly polarized light to the reflecting mirror.

7. A head-up display as claimed in any one of claims 1 to 3, wherein when the PVG device is a PVG array, a side of the PVG array facing away from the first polarizer is provided with a corrective element; and the correcting element is a reflecting element or a diffracting element; the correcting element is used for diffracting or reflecting the projection light rays output by the projection light machine and transmitted by the first polarizer and the PVG array in sequence to the PVG array;

the PVG optical fiber correction device further comprises a plurality of second polarizers which are sequentially arranged on an output optical path of the correction element, and each second polarizer is correspondingly arranged on an input optical path of one PVG element; the second polarizer is used for modulating light rays which are output by the correcting element and sequentially enter the PVG elements corresponding to the second polarizer into elliptically polarized light, so that the corresponding PVG elements can perform partial diffraction and partial transmission on the elliptically polarized light, and the polarization states of the elliptically polarized light formed by modulation of the second polarizers are not identical.

8. A heads-up display as claimed in any one of claims 1 to 3 wherein when the PVG device is a PVG array, the PVG array comprises a first PVG array and a second PVG array;

wherein the first PVG array comprises a plurality of first PVG elements arranged in sequence on an output optical path of the first polarizer; the second PVG array comprises a plurality of second PVG elements which are sequentially arranged on the diffraction output optical path of the first PVG array; the straight line where the first PVG array is located and the straight line where the second PVG array is located are not coincident or parallel;

each of the first PVG elements is configured to diffract the output circularly polarized light of the first polarizer to output diffracted light, and the diffracted light passes through each of the second PVG elements in sequence, is partially diffracted and partially transmitted by each of the second PVG elements, and is incident on the mirror.

9. A head-up display as claimed in claim 8 wherein a side of the first PVG array facing away from the projection light engine is provided in sequence with a first wave plate and a first corrective element; and a second wave plate and a second correcting element are sequentially arranged on one side of the second PVG array, which is far away from the first PVG array.

10. A head-up display as claimed in any one of claims 1 to 3 wherein, when the PVG device is a PVG array, each PVG element of the PVG array is adapted to diffract other bands of polarized light components for transmission of a specific band of circularly polarized light component of incident polarized light, and the corresponding diffractable circularly polarized light of each PVG element has a different band range.

11. A head-up display as claimed in any one of claims 1 to 3, wherein when the PVG device is a PVG array, an optical waveguide for one-dimensional pupil expansion of the projected light output by the optical projector is further provided between the optical projector and the first polarizer;

and the projection light output by the projection light machine enters the first polarizer after passing through the optical waveguide one-dimensional pupil expansion.

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