1. A heads-up display, comprising:

a light source module for projecting a light beam;

the spatial light modulator is used for modulating the light beam into a first image and a second image and projecting image light of the first image and the second image;

an imaging screen set for reflecting the image light of the first image and the second image to the visible range of a user so that the user can see the first image and the second image; and

a control unit coupled to the spatial light modulator for inputting at least two modulation signals to control the light splitting mechanism of the spatial light modulator.

2. The head-up display of claim 1 wherein the spatial light modulator displays two computer holograms with one of a liquid crystal or liquid crystal on silicon panel and modulates at least one of phase and amplitude of the incident beam for diffraction imaging.

3. The head-up display of claim 1 wherein the spatial light modulator modulates the light beam in an angle-multiplexing beam-splitting scheme to image the first image and the second image at different angles and distances.

4. The head-up display of claim 3, wherein the at least two modulation signals comprise diffraction apertures of two gratings, which are respectively corresponding to imaging positions of the first image and the second image at different angles and distances, and the control unit inputs the two gratings into the spatial light modulator and controls the imaging positions of the reconstructed first image and the reconstructed second image according to the two gratings to respectively project the first image and the second image onto the imaging screen set.

5. The heads-up display of claim 1 wherein the set of imaging screens are transparent screens or reflective screens.

6. A heads-up display, comprising:

a light source module for projecting a light beam;

a spatial light modulator for modulating the light beam into a first image and a second image and projecting the first image and the second image;

an imaging screen set for reflecting the first image and the second image to the visual range of a user so that the user can see the first image and the second image; and

and the light splitting element is arranged between the spatial light modulator and the imaging screen set and is used for splitting the light beam into a penetrating light beam and a reflecting light beam, the penetrating light beam forms the first image, and the reflecting light beam forms the second image.

7. The head-up display of claim 6 wherein the spatial light modulator displays two computer holograms with one of a liquid crystal or liquid crystal on silicon panel and modulates at least one of phase and amplitude of the incident beam for diffraction imaging.

8. The head-up display of claim 7 wherein the spatial light modulator modulates the light beam with a polarization-multiplexing beam splitting scheme to image the first image and the second image at orthogonal imaging positions.

9. The head-up display of claim 6, further comprising at least one polarization control element disposed between the spatial light modulator and the beam splitting element, the polarization control element configured to change the light beam into two orthogonal polarizations.

10. The head-up display of claim 9, further comprising at least one wave plate disposed between the beam splitting element and the image screen set, the wave plate being configured to change the phase retardation of the two polarized lights.

Background

A head-up display (HUD) is used to display driving data (such as vehicle speed, fuel amount, navigation information, etc.) in a visible range in front of the eyes of the driver, so that the driver can see the projected image of the display and the situation in front of the vehicle at the same time.

In order to achieve the purpose of three-dimensional display, the existing head-up display needs a plurality of image generation modules for imaging so as to present two images located at different imaging positions, but the cost is high, or the focal length is adjusted by a focusing lens group so as to adjust the imaging position of a virtual image, but only images at a single distance can be presented at one time, and it is difficult to present two images located at different imaging positions at the same time.

Disclosure of Invention

The invention relates to a head-up display, which can achieve the effect of simultaneously displaying different images at different imaging positions by utilizing a spatial light modulator of a multi-light-splitting mechanism.

According to an aspect of the present invention, a head-up display is provided, which includes a light source module, a spatial light modulator, an imaging screen set and a control unit. The light source module is used for projecting a light beam. The spatial light modulator is used for modulating the light beam into a first image and a second image and projecting image light of the first image and the second image. The imaging screen set is used for reflecting the image light of the first image and the second image to the visible range of a user, so that the user can see the first image and the second image. The control unit is coupled to the spatial light modulator and is used for inputting at least two modulation signals to control a light splitting mechanism of the spatial light modulator.

According to an aspect of the present invention, a head-up display is provided, which includes a light source module, a spatial light modulator, an imaging screen set and a light splitting element. The light source module is used for projecting a light beam. The spatial light modulator is used for modulating the light beam into a first image and a second image and projecting image light of the first image and the second image. The imaging screen set is used for reflecting the image light of the first image and the second image to the visible range of a user, so that the user can see the first image and the second image. The light splitting element is arranged between the spatial light modulator and the imaging screen group and is used for splitting the light beam into a penetrating light beam and a reflecting light beam, the penetrating light beam forms a first image, and the reflecting light beam forms a second image.

In order to better appreciate the above and other aspects of the present invention, the following detailed description of the embodiments is provided in conjunction with the accompanying drawings.

Drawings

Fig. 1 is a schematic diagram of a head-up display according to an embodiment of the invention.

FIG. 2 is a schematic diagram of a head-up display according to another embodiment of the invention.

FIG. 3 is a schematic diagram of a head-up display according to another embodiment of the invention.

Fig. 4 is a schematic diagram illustrating polarization splitting of the spatial light modulator by the polarization control element according to an embodiment of the invention.

Detailed Description

The following embodiments are provided for illustrative purposes only and are not intended to limit the scope of the present invention. The following description will be given with the same/similar reference numerals as used for the same/similar elements. Directional terms as referred to in the following examples, for example: up, down, left, right, front or rear, etc., are referred to only in the direction of the attached drawings. Accordingly, the directional terminology is used for purposes of illustration and is in no way limiting.

According to an embodiment of the present invention, a head-up display with a multi-beam splitting mechanism is provided for a vehicle to achieve two-dimensional or three-dimensional display. The head-up display only has a single light source module, and performs multi-wavelength light splitting on a single light beam by using the spatial light modulator so as to achieve the effect of simultaneously displaying different images at different imaging positions. Therefore, the head-up display does not need to use a plurality of image generation modules for imaging, so that the cost is saved. In addition, since the two-dimensional image does not contain depth information, the three-dimensional image cannot be reconstructed. The invention utilizes an angle multiplexing light splitting or polarization multiplexing light splitting mechanism to simultaneously display different images on imaging positions at different angles and distances, thereby achieving the purpose of three-dimensional display.

In one embodiment, the spatial light modulator modulates the light beam by a diffractive optical element such as a liquid crystal display element (lcd), a computer-generated holograms (CGH), etc., wherein the lcd element is a transmissive liquid crystal or reflective liquid crystal on silicon (LCoS) spatial light modulator, which can modulate the amplitude, phase and both of the incident light beam by controlling the tilt angle of the liquid crystal molecules with an applied voltage to adjust the polarization state or polarization angle of the incident light beam. In one embodiment, the control unit can input two computer holograms onto respective display surfaces of the liquid crystal display device and inject the two computer holograms into the liquid crystal display device in parallel beams at appropriate angles, and the beams are imaged by optical Fourier transform to reconstruct a target image light field in a Fourier plane. Therefore, as long as the distance between the imaging screen set and the two computer holograms can meet the far-field diffraction condition, the two reconstructed images can be respectively displayed on the imaging screen set.

In one embodiment, the head-up display with the multi-beam splitting mechanism can display real images of the first image and the second image on a reflective screen for a user to watch, or display virtual images of the first image and the second image on an imaging position outside a transparent screen (such as a windshield), so that a driver can see the projected images and the situation in front of the vehicle at the same time, thereby realizing the augmented reality.

Referring to fig. 1, a schematic diagram of a head-up display 100 according to an embodiment of the invention is shown. The head-up display 100 includes a light source module 110, a spatial light modulator 120, an imaging screen set 130, and a control unit 140. The light source module 110 is used for projecting a light beam L. The spatial light modulator 120 is used for modulating the light beam L into a first image and a second image and projecting image lights R1 and R2 of the first image and the second image. The imaging screen set 130 is used for reflecting the image lights R1 and R2 of the first image and the second image to the visible range of the eyes E of the user, so that the user sees the first image and the second image or respective virtual images of the first image and the second image. The control unit 140 is coupled to the spatial light modulator 120 and is configured to input at least two modulation signals to control the light splitting mechanism of the spatial light modulator 120.

The light source module 110 may be an optical module, a laser light source, or a Light Emitting Diode (LED) light source, and the light source module 110 may project a light beam L to the spatial light modulator 120, where the light beam L may be a parallel light or a spherical wave, and the light beam L is modulated into the first image and the second image by the spatial light modulator 120 and imaged. The image lights R1 and R2 of the respective images are projected to the set of imaging screens 130 via the spatial light modulator 120 for the user to view.

The spatial light modulator 120 may be an optical device such as a transmissive liquid crystal panel, a reflective liquid crystal on silicon panel, or the like. As shown in fig. 1, the spatial light modulator 120 displays two computer holograms a1, B1, for example, by a liquid crystal or liquid crystal on silicon panel, and modulates at least one of the phase and amplitude of the incident light beam L to perform diffraction imaging. In order to achieve the angular multiplexing, the at least two modulation signals include diffraction apertures of two gratings a2 and B2, which are respectively used to adjust the first image and the second image to imaging positions with different angles and distances. The control unit 140 inputs the diffraction apertures (i.e., modulation signals) of the two gratings a2 and B2 into the spatial light modulator 120, and controls the imaging positions of the reconstructed first image and second image according to the two gratings a2 and B2, so that the image lights R1 and R2 of the first image and the second image are respectively projected to the first screen 131 and the second screen 132 of the imaging screen group 130 for the user to view.

The imaging screen set 130 may be a transparent screen or a reflective screen. If a reflective screen is used, real images of the first image and the second image may be displayed on the reflective screen. The reflective screen may be a flat mirror or a concave mirror (concave mirror) 136. If a transparent screen is used, the first image and the second image generate virtual images through the transparent screen, and the respective virtual images are displayed at the imaging positions. In one embodiment, the transparent screen may be a vehicle windshield 134 or a beam splitter called a combiner (combiner).

Referring to fig. 2, a schematic diagram of a head-up display 101 according to another embodiment of the invention is shown. The head-up display 101 includes a light source module 110, a spatial light modulator 120, an imaging screen assembly 130, and a light splitting element 150. The light source module 110 is used for projecting a light beam L. The spatial light modulator 120 is used for modulating the light beam L into a first image and a second image and projecting image lights R1 and R2 of the first image and the second image. The imaging screen set 130 is used for reflecting the image lights R1 and R2 of the first image and the second image to the visible range of the eyes E of the user, so that the user sees the first image and the second image or respective virtual images of the first image and the second image. The light splitting element 150 is disposed between the spatial light modulator 120 and the image screen assembly 130, and the light splitting element 150 is configured to split the light beam L into a penetrating light beam and a reflecting light beam, where the penetrating light beam forms a first image and the reflecting light beam forms a second image.

As described in the above embodiments, the spatial light modulator 120 may be an optical element such as a transmissive liquid crystal panel, a reflective liquid crystal on silicon panel, or the like. The spatial light modulator 120 displays two computer holograms, for example, by a liquid crystal or liquid crystal on silicon panel, and modulates at least one of the phase and amplitude of the incident light beam L to perform diffraction imaging. The difference between the above embodiments is that the light splitting element 150 is used to split the light beam L into a transmitted light beam and a reflected light beam. The transmitted light beam can pass through the light splitting element 150 to form a first image on the first screen 131, and then the image light R1 of the first image is reflected by the light splitting element 150 and projected to the transparent screen, so as to present a virtual image VM1 of the first image outside the transparent screen. The reflected light beam may be reflected by the light splitting element 150 to form a second image on the second screen 132, and then the image light R2 of the second image may pass through the light splitting element 150 and be projected to the transparent screen, so as to present a virtual image VM2 of the second image outside the transparent screen. In one embodiment, the transparent screen may be a vehicle windshield 134 or a beam splitter called a combiner (combiner).

In addition, the head-up display 101 may further include at least one polarization control element 151, 152 disposed between the spatial light modulator 120 and the light splitting element 150, wherein the polarization control element 151, 152 is used to change the light beam L into two orthogonal polarized lights LP1, LP 2. The polarization control elements 151, 152 are, for example, polarizers or waveplates 153, 154. That is, the two orthogonal polarized lights LP1 and LP2 are divided into a transmitted light beam and a reflected light beam by the light splitting element 150, and then the first image on the first screen 131 and the second image on the second screen 132 are overlapped by the light splitting element 150 and finally projected to the transparent screen. By the polarization multiplexing mechanism, the image output by the spatial light modulator 120 can be spatially divided into two orthogonally polarized light fields.

In addition, the head-up display 101 may further include at least one wave plate (wave plate)153, 154 disposed between the light splitting element 150 and the image screen set 130, wherein the wave plate 153, 154 is used to change the phase retardation (phase retardation) of the two polarized lights LP1, LP 2. As shown in fig. 2, the first wave plate 153 is disposed between the light splitting element 150 and the first screen 131, and the second wave plate 154 is disposed between the light splitting element 150 and the second screen 132. By the polarization multiplexing mechanism, the image output by the spatial light modulator 120 can be spatially divided into two orthogonally polarized light fields.

The polarization control elements 151 and 152 and the wave plates 153 and 154 may be used simultaneously or separately, and the number of the polarization control elements and the wave plates may be one or more, which is not limited in this embodiment.

Referring to fig. 3, a schematic diagram of a head-up display 102 according to another embodiment of the invention is shown. The light splitting mechanism employed by the head-up display 102 of this embodiment is similar to that of the embodiment of fig. 2, except that: the transmitted light beam can pass through the light splitting element 150 to form a first image on the first screen 131, for example, the first screen 131 is a transparent screen, and then the first image is generated into a virtual image VM1 by the first screen 131, so that the virtual image VM1 of the first image is shown outside the transparent screen (for example, the windshield 134). In addition, the reflected light beam may be reflected to an optional reflector 133 via the light splitting element 150, and form a second image on the second screen 132, where the second screen 132 is, for example, a transparent screen, and then the second image generates a virtual image through the second screen 132, so as to present the virtual image VM2 of the second image outside the transparent screen (e.g., the windshield 134).

As with the above embodiments, the head-up display 102 further includes at least one polarization control element 151, 152 disposed between the spatial light modulator 120 and the light splitting element 150, wherein the polarization control element 151, 152 is used to change the light beam L into two orthogonal polarized lights LP1, LP 2. In addition, the head-up display 100 may further include at least one wave plate 153, 154 disposed between the beam splitting element 150 and the image screen set 130, wherein the wave plate 153, 154 is used to change the phase retardation of the two polarized lights LP1, LP 2.

The polarization control elements 151 and 152 and the wave plates 153 and 154 may be used simultaneously or separately, and the number of the polarization control elements and the wave plates may be one or more, which is not limited in this embodiment.

Fig. 4 is a schematic diagram showing the spatial light modulator 120 performing polarization splitting by the polarization control elements 151 and 152 according to an embodiment of the invention. In one embodiment, the spatial light modulator 120 is used to display two computer holograms A1, B1 on respective display surfaces. In order to achieve polarization-multiplexed light splitting, when the spatial light modulator 120 outputs two computer holograms a1 and B1, two polarization control devices 151 and 152 with different polarization states are respectively disposed in front of the corresponding two computer holograms a1 and B1, so that the incident light beam L passes through the two polarization control devices 151 and 152 to become two orthogonal polarized lights LP1 and LP2, which is beneficial to the subsequent polarization-multiplexed light splitting.

The head-up display of the embodiment of the invention can avoid the problem that the existing head-up display needs a plurality of image generating modules for imaging or the focus is adjusted by the adjustable focus lens group, but only images with single distance can be presented at one time and two images positioned at different imaging positions are difficult to be presented at the same time. In addition, the head-up display of the above embodiment utilizes the spatial light modulator to perform multi-wavelength light splitting on a single light beam, such as an angle multi-wavelength light splitting mechanism or a polarization multi-wavelength light splitting mechanism, and simultaneously displays different images at imaging positions with different angles and distances, thereby achieving the purpose of three-dimensional display and also achieving the purpose of reality expansion.

In summary, although the present invention has been described with reference to the above embodiments, the present invention is not limited thereto. Various modifications and alterations may be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention should be determined by the appended claims.