Head-up display
By introducing a microcontroller and photoelastic modulator into the optical waveguide display, combined with specially designed grating areas and light absorption areas, the problems of stray light coupling and interference in open environments are solved, achieving clearer image display effects.
Patent Information
- Application Number
- CN202511063917.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-30
- Publication Date
- 2025-09-16
AI Technical Summary
In an open environment, optical waveguide displays are prone to stray light coupling, diffraction light interference and signal overlap, affecting the viewing experience.
The combined design of a microcontroller, a photoelastic modulator, an optical coupling region, an optical waveguide, a grating region and a light absorption region is adopted. The spatial polarization state of the image is modulated by the photoelastic modulator, and the specially designed grating region is used to filter out stray light, while the light absorption region absorbs stray light to improve image clarity.
Effectively reduce the impact of stray light on the viewing experience, ensuring that users only see clear structured light, improving the overall viewing experience.
Smart Images
Figure CN120652685A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of electronic equipment, and in particular to a head-up display. Background Art
[0002] With the widespread use of various automotive auxiliary displays and optical waveguides, displays integrating optical waveguides with vehicles and various transportation vehicles have also seen significant development. In optical waveguide applications, the typical approach is to use an optical engine to project the required light into the waveguide's coupling region. This is feasible in enclosed or low-noise environments, but the situation becomes slightly different in open environments.
[0003] Because related optical waveguides all use fixed gratings to couple light into the waveguide, these gratings are generally sensitive to incident angle and wavelength but lack the ability to selectively couple spatial patterns. Therefore, in strong light environments or with multiple signals, they are prone to problems such as stray light coupling, diffracted light interference, and signal overlap. This can lead to unnecessary additional noise when using these optical waveguides, affecting the viewing experience. Summary of the Invention
[0004] Based on this, the present application provides a head-up display to improve the viewing experience.
[0005] According to one embodiment of the present application, a head-up display includes a microcontroller, a photoelastic modulator, a light coupling region, an optical waveguide, a grating region, and a light absorption region. The microcontroller is configured to process pixel displacement of an image. The photoelastic modulator is electrically connected to the microcontroller and configured to modulate the spatial polarization state of the image to a spatial frequency. The light coupling region is optically coupled to the photoelastic modulator and configured to couple in the image. The optical waveguide is optically coupled to the light coupling region and is located between the light coupling region and the photoelastic modulator. The grating region is located next to the light coupling region and directly contacts the optical waveguide, and is configured to couple out the image of the spatial frequency. The light absorption region is arranged around the optical waveguide.
[0006] In one embodiment of the present application, the grating region is further configured to reflect stray light to the light absorption region.
[0007] In one embodiment of the present application, the photoelastic modulator is further configured to modulate two different spatial polarization states according to pixel displacement.
[0008] In one embodiment of the present application, the light absorbing region includes a non-reflective black light absorbing material.
[0009] In one embodiment of the present application, the head-up display further includes a light source configured to emit a processed image to the photoelastic modulator.
[0010] In one embodiment of the present application, the microcontroller is further configured to synchronize the light source and the photoelastic modulator.
[0011] In one embodiment of the present application, the grating region is further configured to cause destructive interference of light that does not conform to the spatial frequency.
[0012] In one embodiment of the present application, pixel shifting includes inserting a black pixel between two pixels of the original image.
[0013] In one embodiment of the present application, the light coupling region directly contacts the grating region.
[0014] In one embodiment of the present application, the outcoupling efficiency of the grating region when the electric field is perpendicular to the diffraction plane is higher than the outcoupling efficiency when the electric field is parallel to the diffraction plane.
[0015] In the above-mentioned embodiment of the present application, since the head-up display has a photoelastic modulator and a specially designed grating area, light that does not conform to the spatial frequency modulated by the photoelastic modulator (i.e., stray light) will be filtered out by the grating when coupled out, thereby reducing the impact of stray light on the viewing experience, leaving only the structured light modulated by the photoelastic modulator in the user's eyes, making the overall viewing experience clearer. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] When accompanied by Figure 1 When read together, the embodiments of the present application are best understood from the following description. Note that according to standard practice in this industry, various features are not drawn to scale. In fact, the dimensions of various features may be arbitrarily increased or decreased for clarity of discussion.
[0017] Figure 1 2 is a cross-sectional view of a head-up display according to one embodiment of the present application.
[0018] Figure 2 for Figure 1 Schematic diagram of pixel displacement of the head-up display.
[0019] Figure 3 for Figure 1 Schematic diagram of the photoelastic modulator modulating the image in the head-up display.
[0020] Figure 4 for Figure 1 A partial enlarged view of the optical waveguide and grating area of the head-up display.
[0021] Figure 5 for Figure 1 Schematic diagram of a head-up display in which the grating area reflects light of another polarization state to the light absorption area.
[0022] Figure 6 for Figure 1 Schematic diagram of the grating area of the head-up display reflecting stray light to the light-absorbing area.
[0023] Description of reference numerals:
[0024] 100: head-up display;
[0025] 110: microcontroller;
[0026] 120: photoelastic modulator;
[0027] 130: light coupling region;
[0028] 140: optical waveguide;
[0029] 150: grating area;
[0030] 160: light absorption area;
[0031] 170: light source;
[0032] 200: original image;
[0033] 210: pixel displacement;
[0034] 220: image signal;
[0035] 300: structured light;
[0036] A: Stray light;
[0037] A±1: scattered light;
[0038] P1, P2, P3: pixels;
[0039] TE: polarization state;
[0040] TM: polarization state. DETAILED DESCRIPTION
[0041] The embodiments disclosed below provide many different embodiments, or examples, for implementing the various features of the provided objectives. Specific examples of components and arrangements are described below to simplify the present invention. Of course, these examples are merely examples and are not intended to be limiting. Furthermore, the present invention may repeat element symbols and / or letters in each example. This repetition is for the purpose of simplicity and clarity and does not, in itself, specify the relationship between the various embodiments and / or configurations discussed.
[0042] Spatially relative terms such as "below," "beneath," "lower," "above," "upper," and the like may be used herein for descriptive purposes to describe one element or feature's relationship to another element or feature as illustrated in the accompanying drawings. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the accompanying drawings. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein should likewise be interpreted accordingly.
[0043] As used herein, "approximately," "about," "approximately," or "substantially" generally means within 20 percent, or within 10 percent, or within 5 percent of a given value or range. Numerical values given herein are approximate, indicating that the use of terms such as "approximately," "about," "approximately," or "substantially" can be inferred when not explicitly stated.
[0044] Figure 1 FIG is a cross-sectional view of a head-up display 100 according to an embodiment of the present application. Figure 1 The head-up display includes a microcontroller 110, a photoelastic modulator 120, a light coupling region 130, an optical waveguide 140, a grating region 150, and a light absorption region 160. The microcontroller 110 is configured to process pixel shift of an image (to be Figure 2 The photoelastic modulator 120 is electrically connected to the microcontroller 110 and configured to modulate the spatial polarization state of the image to a specific spatial frequency. At this spatial frequency, the spatial polarization state of the image will be the same at every fixed distance (the Figure 3 Detailed description). The light coupling-in region 130 is optically coupled to the photoelastic modulator 120 and is configured to couple the image into the optical waveguide 140. The optical waveguide 140 is optically coupled to the light coupling-in region 130 and is located between the light coupling-in region 130 and the photoelastic modulator 120. The grating region 150 is located next to the light coupling-in region 130 and directly contacts the optical waveguide 140, and is configured to couple out the image that conforms to the spatial frequency. The light absorption region 160 is arranged around the optical waveguide 140. In some embodiments, the light absorption region 160 may be discontinuously arranged, but may be composed of several shells, which does not affect the implementation of the present application. In some embodiments, the light coupling-in region 130 directly contacts the grating region 150.
[0045] Because the head-up display 100 has a photoelastic modulator 120 and a specially designed grating area 150, light that does not conform to the spatial frequency modulated by the photoelastic modulator 120 (i.e., stray light) will be filtered out by the grating area 150 during outcoupling, thereby reducing the impact of stray light on the viewing experience. Only the structured light modulated by the photoelastic modulator 120 remains in the user's eyes, making the overall viewing experience clearer.
[0046] In this embodiment, the head-up display 100 further includes a light source 170, located between the microcontroller 110 and the photoelastic modulator 120. The light source 170 is configured to emit an image processed by the microcontroller 110 to the photoelastic modulator 120. The microcontroller 110 is also configured to synchronize the light source 170 with the photoelastic modulator 120. Because the photoelastic modulator 120 can achieve a higher temporal frequency than both the light source 170 and the microcontroller 110, the microcontroller 110 reduces the temporal frequency of the photoelastic modulator 120 to ensure synchronization between the photoelastic modulator 120 and the light source 170, thereby modulating appropriate structured light.
[0047] Figure 2 for Figure 1 Schematic diagram of pixel displacement 210 of the head-up display 100. Figure 2 When the microcontroller 110 of the head-up display 100 receives the signal of the original image 200, the microcontroller 110 does not immediately output the original image, but performs pixel shift 210. The pixel shift 210 includes inserting a black pixel between two pixels of the original image 200. For example, Figure 2 For example, the original image 200 is divided into four pixels. When the pixels are shifted by 210, a black pixel will be inserted between any two pixels. If there is an empty pixel and its four sides are all black pixels, then a black pixel will also be filled in when the pixels are shifted by 210 (for example Figure 2 Therefore, assuming that there is a pixel point with coordinates (X1, Y1) before the pixel shift of 210, then after the pixel shift of 210, the pixel after the shift (X2, Y2) can be expressed as follows:
[0048] (X2, Y2) = (2X1-1, 2Y1-1) ... Formula 1
[0049] Specifically, in the image signal 220 after the pixel shift 210, only pixels where both (X2, Y2) are odd numbers are pixels of the original image 200. Pixels where either or both (X2, Y2) are even numbers are black pixels. After the pixel shift 210 is completed, the microcontroller 110 will continue to output the image signal 220 to the light source 170.
[0050] Figure 3 for Figure 1 Schematic diagram of the photoelastic modulator 120 modulating the image of the head-up display 100. Figure 3. After the image signal 220 is transmitted to the photoelastic modulator 120, the microcontroller 110 synchronously controls the temporal frequency of the photoelastic modulator 120 so that the photoelastic modulator 120 can perform special spatial modulation on the spatial frequency of the image signal 220. The photoelastic modulator is also configured to modulate two different spatial polarization states according to pixel displacement. Specifically, the photoelastic modulator 120 is configured so that the image signal 220, after modulation, presents a TE polarization state (the electric field is perpendicular to the diffraction plane) at the position where the image is present, and presents a TM polarization state (the electric field is within the diffraction plane) at the position of the black pixel. This design is achieved by using the microcontroller 110 to adjust the temporal frequency of the photoelastic modulator 120 and the light source 170 to be consistent, and this design enables the structured light 300 to have a unique spatial frequency, which can help filter light after the structured light 300 enters the waveguide.
[0051] Figure 4 for Figure 1 A partial enlarged view of the optical waveguide 140 and the grating area 150 of the head-up display 100. Figure 4 After the photoelastic modulator 120 has completed the modulation of the structured light 300, the structured light 300 is directed toward the light coupling region 130 (see FIG. Figure 1 ) transmission, the light coupling region 130 then couples the structured light 300 into the optical waveguide 140. The structured light 300 is then totally reflected in the optical waveguide 140 and simultaneously transmitted to the grating region 150. Due to the modulation of the structured light 300 by the photoelastic modulator 120, the Nyquist frequency of the structured light image is half the spatial frequency of the original structured light 300. Therefore, the Bragg grating period Λ can be determined according to the wavelength λ, the spatial frequency f0, and the coupling angle θ, namely:
[0052] ...Formula 2
[0053] ...Formula 3
[0054] where n effis the equivalent refractive index. The frequency of the coupling position of the structured light image is f0=1 / 2d, and the coupling position of the structured light image without an image is f0=1 / d, where d is the distance between the two closest lights coupled into the waveguide (for example, the distance between the pixel P1 with a signal and the stray light A). Therefore, the grating shape and grating period can be calculated. Such a design can make a design on the grating area 150 that only allows the structured light 300 in the TE polarization state to be coupled out to the user's eyes. This is because the outcoupling efficiency of the grating area 150 when the electric field is perpendicular to the diffraction plane (i.e., TE polarization) is higher than the outcoupling efficiency when the electric field is parallel to the diffraction plane (i.e., TM polarization). In some embodiments, the outcoupling efficiency of the grating area 150 when the electric field is parallel to the diffraction plane is essentially zero. In addition, the grating area 150 is also configured to cause destructive interference of light that does not conform to the spatial frequency, further filtering out light from the external environment that has not undergone any special modulation. In some embodiments, the grating region 150 also has the function of filtering out high-order scattered light (such as first-order scattered light A±1 of stray light A), ensuring that the image entering the user's field of view is free of high-order scattered light.
[0055] Figure 5 for Figure 1 Schematic diagram of the grating area 150 of the head-up display 100 reflecting light of another polarization state TM to the light absorption area 160. Figure 5 If the light of the non-corresponding polarization state (assuming it is TM polarization state) happens to hit the outcoupling grating designed for TE polarization state light, then at this time, due to the equivalent refractive index n of the two polarization states eff Because the polarization states are different, they cannot be coupled out smoothly. Therefore, in this case, the light of the non-corresponding polarization state will be refracted out of the optical waveguide 140 and then go to the external light absorption area 160. The light absorption area 160 is composed of a non-reflective black light-absorbing material, so the reflected light will be directly absorbed and will not be seen by the user.
[0056] Figure 6 for Figure 1 Schematic diagram of the grating area 150 of the head-up display 100 reflecting stray light A to the light absorption area 160. Figure 6 , in the case where the light hitting the grating area 150 is stray light A, Figure 5 The situation is similar. Due to the equivalent refractive index n eff Different from the above, the stray light A cannot be coupled out smoothly, but will be reflected to the light absorption area 160. Therefore, the grating area 150 is also configured to reflect the stray light A to the light absorption area 160. The light absorption area 160 is also responsible for absorbing the stray light A so that the stray light A will not enter the user's eyes. It is worth mentioning that Figure 6The embodiment described here is the case when the stray light A is not high-order scattered light. If it is high-order scattered light, the scattering direction will be different, but because the spatial frequency does not meet the setting requirements of the grating area 150, it will still not be successfully coupled out into the user's field of view.
[0057] The foregoing summarizes the features of several embodiments so that those skilled in the art can better understand the various aspects of the present application. Those skilled in the art will appreciate that they can easily use this application as a basis for designing or modifying other processes and structures to achieve the same purposes and / or achieve the same advantages as the embodiments described herein. Those skilled in the art will also appreciate that such equivalent constructions do not depart from the spirit and scope of the present application, and that various changes, substitutions, and modifications may be made herein without departing from the spirit and scope of the present application.
Claims
1. A head-up display, characterized in that: The head-up display comprises: a microcontroller configured to process pixel shifting of an image; a photoelastic modulator electrically connected to the microcontroller and configured to modulate the spatial polarization state of the image to a spatial frequency; an optical coupling region, optically coupled to the photoelastic modulator and configured to couple the image; an optical waveguide optically coupled to the light coupling-in region and located between the light coupling-in region and the photoelastic modulator; a grating region, located adjacent to the light coupling region and directly contacting the optical waveguide, configured to couple out the image at the spatial frequency; and The light absorbing region is arranged around the optical waveguide.
2. The head-up display according to claim 1, wherein: The grating region is further configured to reflect stray light toward the light absorption region.
3. The head-up display according to claim 1, wherein: The photoelastic modulator is further configured to modulate two different spatial polarization states according to the pixel displacement.
4. The head-up display according to claim 1, wherein: The light absorbing area includes a non-reflective black light absorbing material.
5. The head-up display according to claim 1, wherein: The head-up display further includes: The light source is configured to emit the processed image to the photoelastic modulator.
6. The head-up display according to claim 5, wherein: The microcontroller is further configured to synchronize the light source with the photoelastic modulator.
7. The head-up display according to claim 1, wherein: The grating region is further configured to cause destructive interference of light that does not conform to the spatial frequency.
8. The head-up display according to claim 1, wherein: The pixel shifting includes inserting a black pixel between two pixels of the original image.
9. The head-up display according to claim 1, wherein: The light coupling region directly contacts the grating region.
10. The head-up display according to claim 1, wherein: The out-coupling efficiency of the grating region when the electric field is perpendicular to the diffraction plane is higher than the out-coupling efficiency when the electric field is parallel to the diffraction plane.