CN115097637A

Movatterモバイル変換

Info

Publication number: CN115097637A
Application number: CN202211029426.0A
Authority: CN
Inventors: 魏一振; 陈飞鸿; 张卓鹏
Original assignee: Hangzhou Guangli Technology Co ltd
Current assignee: Hangzhou Guangli Technology Co ltd
Priority date: 2022-08-26
Filing date: 2022-08-26
Publication date: 2022-09-23
Anticipated expiration: 2042-08-26
Also published as: CN115097637B

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 output to projection light among 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 subject to projection ray apparatus spatial dimension, be favorable to head-up display to show driving information more effectively, 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-mentioned 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 on 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 rays 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 which have 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, according to a corresponding set proportion, partial diffraction and partial transmission on the entered polarized light 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 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 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 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.

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;

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 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 optical projector is limited by the installation space of the head-up display, and the size of the projection picture output by the optical projector is limited 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, and then the eye box corresponding to the head-up display system is enlarged is provided, and the wide application of the head-up display is facilitated. In order that those skilled in the art will better understand the disclosure, the invention will be described in further detail with reference to the accompanying drawings and specific embodiments. 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 projectionlight machine 1 for outputting projection light;

afirst polarizer 2 arranged on an output optical path of the projection light machine;

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

and the reflectingmirror 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 theoptical 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, thefirst polarizer 2 in this embodiment may be a device capable of modulating the projection light output by theprojection 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 reflectingmirror 4 in the present embodiment, it 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 previously described, PVG devices can exist in a variety of different implementations.

In the embodiment where the PVG device is amonolithic PVG element 30, the PVG device can be implemented by utilizing the characteristic that themonolithic 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, thefirst polarizer 2 may be a wave plate, or may be another type of polarizer, as long as the projection light output by theprojector 1 can be modulated to form linearly polarized light meeting the diffraction requirement of themonolithic PVG element 30, at this time, themonolithic 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 themirror 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.

In addition, in the embodiment shown in fig. 3, only onemonolithic PVG element 30 is included, and left-circularly polarized light, right-circularly polarized light and transmitted light output by themonolithic PVG element 30 in a single direction are located in the same plane, that is, themonolithic 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 projectionoptical 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 theprojection light engine 1 projects and displays two-dimensional images, and therefore, a two-dimensional pupil expansion is often required for theprojection light engine 1 to clearly display a specific embodiment of a projection picture. To this end, in an alternative embodiment of the present application, twomonolithic PVG elements 30 may be provided; take the example of a PVG device comprising a first monolithic PVG element and a second monolithic PVG element; accordingly, thefirst polarizer 2 includes a first polarizer one and a first polarizer two;

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

the projectionoptical machine 1, a first polarizer I arranged on an output light path of the projectionoptical 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 projectionlight 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 thesingle 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 amonolithic 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 theprojection light engine 1 and thefirst polarizer 2; the projection light output by the projectionlight machine 1 passes through the optical waveguide one-dimensional pupil and then enters thefirst 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 theprojection light engine 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 it by total reflection, since the surface of the waveguide element 6 is further provided with the outcoupling grating 62, the projection light, during total reflection propagation in the waveguide element 6, passes through the interface between the waveguide element 6 and the outcoupling grating 62 once, partial diffraction and partial reflection can occur, wherein the diffracted light can be coupled out of the waveguide element 6, the reflected light continues to travel onwards by total reflection, until it next reaches the interface between the waveguide 6 and the outcoupling grating 62 again, partial diffraction and partial reflection are generated again, so that one path of diffracted light is output again, and the multi-path diffracted light can be output from different positions of the waveguide element 6 by repeating the operation, so that 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 projectionlight machine 1 passes through the optical waveguide one-dimensional pupil expanding and is output to thefirst 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 thesingle PVG element 30. It is understood that the pupil expanding direction of thesingle 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, and a PVG may also be used, but a polarization device needs to be additionally arranged between the optical waveguide and the projectionoptical machine 1, and other embodiments may also 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 one is a reflection grating.

Further, it is considered that thesingle 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, acorrection element 5 may be further disposed in the optical path between theprojection light engine 1 and themirror 4, and thecorrection element 5 is mainly used for correcting the projection light. Different types of optical elements can be used for thecorrection element 5 depending on the position in which it is arranged.

In an alternative embodiment of the present application, the correctingelement 5 may be disposed between themonolithic PVG element 30 and themirror 4, and the correctingelement 5 may be a reflective element or a diffractive element; the optical path structure of the head-up display may include a projectionoptical machine 1, afirst polarizer 2, amonolithic PVG element 30, acorrection element 5, and amirror 4 in this order.

Projection light output by the projectionlight machine 1 forms circularly polarized light through thefirst polarizer 2, the circularly polarized light is incident to the single-chip PVG element 30 and then is incident to thecorrection element 5 from the single-chip PVG element 30, the light incident to thecorrection element 5 is reflected or diffracted, image distortion is corrected and then output to thereflector 4, and finally the corrected image is reflected and output to human eyes through thereflector 4.

In this embodiment, the correctingelement 5 may be a mirror or a diffractive element, for example, any one of an optical element, such as a flat mirror combining element, a reflective volume holographic grating, and one or more free-form surface mirrors, which is not limited in this application. It is understood that the present application does not exclude the embodiment in which the correctingelement 5 is an optical lens, and for example, the correcting element may be disposed between theprojector engine 1 and thefirst 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 will not be described in detail.

In an alternative embodiment of two-dimensional pupil expansion of the projection light output by the projection light engine, the optical path structure of the head-up display may include: a projectionlight machine 1, an optical waveguide, afirst polarizer 2, amonolithic PVG element 30, acorrection element 5 and amirror 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 expanding of the projection light output by the projector, the optical path structure of the head-up display may include: the projectionoptical 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 reflectingmirror 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, thesingle PVG element 30, and the correctingelement 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 thePVG 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 projectorlight machine 1, afirst polarizer 2, aPVG array 31, and amirror 4.

Thefirst polarizer 2 is used for modulating the projection light into polarized light and sequentially entering each PVG element in thePVG 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 thePVG array 31 is used to diffract incident transmitted circularly polarized light completely to themirror 4.

In this embodiment, the projection optical engine and the reflector are both the same as the projectionoptical engine 1 in any of the above embodiments, and details are not described here. Unlike the embodiment in which the PVG device is amonolithic PVG element 30, thefirst polarizer 2 in this embodiment is a device for modulating the projection light output by theprojection 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., afirst PVG element 311, asecond PVG element 312, and athird 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 projectionlight machine 1 passes through thefirst polarizer 2, the projection light can be modulated by thefirst 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 is output to the human eye by themirror 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 themirror 4 and is 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 thePVG array 31, therefore, the diffraction efficiency of the PVG element three 313 is set to one hundred percent, i.e. total diffraction of the incident transmitted light.

Referring to fig. 5, it can be seen that, each PVG element in thePVG array 31 sequentially diffracts and outputs the projection light onto thereflector 4, so as to realize the diffusion output of the projection light onto thereflector 4, and the diffused projection light is reflected to the human eyes through thereflector 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 this embodiment, the last PVG element in the optical path direction, that is, the 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 light energy that is not diffracted can be ignored.

In addition, for each PVG element in thePVG 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 entering 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 dimension 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 light energy ratio of diffraction and transmission of the PVG element one 311 to the incident light of circularly polarized light can be set to 1: 2; the ratio of diffraction to transmission of the light output by thesecond PVG element 312 to the light output by thefirst PVG element 311 is 1: 1; finally, the third 313 PVG element diffracts the incident light completely; therefore, the energy ratio of the diffracted light output by the PVG element I311, the PVG element II 312 and thePVG element III 313 is 1:1:1 respectively. When the three PVG elements output diffracted light to different positions on thereflector 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, aPVG 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 thePVG array 31 is a transmissive PVG capable of partially diffracting and partially transmitting right circularly polarized light is taken as an example, and in practical applications, an embodiment that each PVG element in thePVG array 31 can partially diffract and partially transmit left circularly polarized light is not excluded as long as thefirst polarizer 2 is correspondingly configured to modulate the light output by the projectionoptical engine 1 into left circularly polarized light. Furthermore, each PVG element in thePVG 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 theprojector 1, the pupil can also 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 projectorlight machine 1, afirst polarizer 2, aPVG array 31, and amirror 4; and each PVG element of thePVG 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.

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 thePVG 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 band, a plurality of PVG elements capable of diffracting circularly polarized light may be provided for each or for each of the projection light beams in a certain wavelength band, and the diffraction efficiencies of the PVG elements for circularly polarized light in the diffractible wavelength band 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 thefirst polarizer 2, so that the circularly polarized light component in the red waveband in the polarized light output by the first polarizer may sequentially pass through the first two R-PVG elements to undergo partial diffraction and partial transmission, and completely diffract through the third R-PVG element, while the circularly polarized light component in the green waveband is sequentially passed through the three R-PVG elements to undergo partial diffraction and partial projection, and is completely diffracted at 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 light imaging pictures with different color wave bands and the pupil expansion of each color wave band light can be realized.

It is considered that thePVG 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 reflective element or a diffractive element as an example, thecorrection element 5 is disposed on the side of thePVG array 31 facing away from the projectionoptical machine 1; awave plate 70 is also arranged between thePVG array 31 and the correctingelement 5;

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

Referring to fig. 6, the projection light output by the projector 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 and be completely transmitted, then enters the correction element through the wave plate 70, passes through the wave plate 70 again after being reflected or diffracted by the correction element 5, the projection light passes through the wave plate 70 twice, the projection light is also converted from left-handed circularly polarized light to right-handed circularly polarized light, the right-handed circularly polarized light enters each PVG element in the PVG array 31 again, first enters the PVG element three 313 to generate partial diffraction and partial transmission, as in the above embodiment, the diffracted light formed by diffraction enters the reflector 4 and is reflected by the reflector 4 and output to human eyes, while the transmitted light enters the PVG element two 312 to generate partial diffraction and partial transmission in the PVG element two 312, similarly, the diffracted light is incident on the reflector, and the transmitted light is incident on the PVG element one 311, where the PVG element one 311 is the last PVG element of the PVG array 31 along the optical path, and can completely diffract the incident light to the reflector 4, thereby implementing pupil expansion of the projected light.

Set upprojection ray machine 1 andcorrection element 5 respectively in this embodiment in the both sides ofPVG array 31 for projection light passes throughPVG 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, thePVG 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 applications. In another alternative embodiment of the present application, the optical path structure of the head-up display may include:

a projectionlight machine 1, afirst polarizer 2, aPVG array 31, acorrection element 5, a plurality of second polarizers and a reflecting mirror;

the side of thePVG array 31 facing away from thefirst polarizer 2 is provided with acorrective element 5; and the correctingelement 5 is a reflecting element or a diffractive element; the correctingelement 5 is used for diffracting or reflecting the projection light output by the projectionlight machine 1 and transmitted by thefirst polarizer 2 and thePVG array 31 in sequence to thePVG array 31;

the device also comprises a plurality of second polarizers which are sequentially arranged on the output optical path of the correctingelement 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 correctingelement 5 and sequentially incident to the PVG elements corresponding to the second polarizer into elliptically polarized light, so that the corresponding PVG elements partially diffract and partially transmit the elliptically polarized light.

It can be understood that the number of the second polarizers in this embodiment 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 correctingelement 5 is firstly incident on thethird polarizer 73 and modulated into elliptically polarized light, thethird PVG element 313 partially diffracts the elliptically polarized light to form diffracted light to be incident on the reflectingmirror 4, and also partially transmits the diffracted light to be output to thesecond polarizer 72, and is modulated again to form elliptically polarized light in another polarization state to be incident on thesecond PVG element 312, thesecond PVG element 312 partially diffracts the elliptically polarized light to form diffracted light to be output to the reflectingmirror 4, and generates partially transmitted light to be incident on thefirst polarizer 71, and is modulated again by thefirst polarizer 71 to form elliptically polarized light in another polarization state, and is finally completely diffracted by thefirst PVG element 311.

It should be noted that, it is necessary for each second polarizer to modulate light that needs to be incident into the corresponding PVG element into elliptically polarized light with different polarization states, in order to implement adjustment of the proportion of diffraction and transmission of the incident light by each PVG element, for the elliptically polarized light with different polarization states, directions of maximum vibration vectors of polarization of the elliptically polarized light are different, and then diffraction efficiencies of the elliptically polarized light that is finally input into the PVG element are also different, and for a specific polarization state of the elliptically polarized light that is modulated and formed by each second polarizer, this application is not specifically limited as long as it is satisfied that energy balance of the diffracted light of each PVG element is finally equalized, or it is satisfied with application requirements.

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

Based on the above discussion, thePVG 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, thePVG array 31 comprises a first PVG array 32 and asecond PVG array 33;

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

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

Still further, in an embodiment where the PVG device includes the first PVG array 32 and thesecond PVG array 33, it is also possible to add acorrective element 5 in the optical path, thecorrective element 5 may include a firstcorrective element 51 and a secondcorrective element 52, and referring to fig. 8, the specific optical path of the corresponding head-up display may include:

one side of the first PVG array 32, which is away from theprojection light engine 1, is sequentially provided with a first wave plate 701 and afirst correction element 51; thesecond wave plate 702 and the second correctingelement 52 are sequentially arranged on the side of thesecond PVG array 33 facing away from the first PVG array 32.

The diffracted light beams diffracted and output by eachfirst PVG element 321 are incident on thesecond PVG array 33, the diffracted light beams also belong to circularly polarized light, the circularly polarized light is transmitted through thesecond PVG array 33, and is incident on thesecond correction element 52 through thesecond wave plate 702, so that the circularly polarized light is diffracted or reflected by thesecond correction element 52 and is output to thesecond PVG array 33 through thesecond wave plate 702 again, eachsecond PVG element 331 in thesecond 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 thefirst PVG element 321, details are not repeated here, and finally the light beams diffracted and output by thesecond PVG element 331 are incident on thereflector 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 thesecond wave plate 702; and each PVG element in the first PVG array 32 and thesecond 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 applications, 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 projectionoptical machine 1, an optical waveguide for performing one-dimensional pupil expansion on projection light output by the projection optical machine, afirst polarizer 2, aPVG array 31 and areflector 4.

Optionally, awave plate 70 and acorrective element 5 may also be provided between thePVG array 31 and themirror 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 thePVG array 31 for the light output by the optical waveguide is the same as the pupil expanding mode of thePVG 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 projectionlight machine 1, afirst polarizer 2, a single-chip PVG element 30, aPVG array 31 and a reflectingmirror 4;

alternatively, acorrection element 5 for correcting the distortion may be further added between themonolithic PVG element 30 and thePVG array 31, and between thePVG array 31 and themirror 4.

The working manner of themonolithic PVG element 30 and thePVG array 31 in this embodiment is similar to that in the above embodiment, and detailed description thereof is omitted 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 should be noted that, in this document, relational terms such as first and second, and the like are 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 elements inherent in the list. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical 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

1. A head-up display, comprising:

a projection light machine for outputting projection light;

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;

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 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 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;

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 device also comprises a plurality of second polarizers which are sequentially arranged on the output optical path of the correcting element, 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 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;

9. A head-up display as claimed in claim 8, characterized in that the side of the first PVG array facing away from the projection light engine is provided in succession 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;