Display module

Abstract

A display module includes a coherent light source, a beam splitter, a spatial light modulator, a lens system, a mirror, and a volumetric holographic optical element. The beam splitter is located above the coherent light source. The spatial light modulator is located on one side of the beam splitter and configured to modulate a plurality of light rays, each ray having an imaging plane different from the others. The lens system is located on the side of the beam splitter opposite to the spatial light modulator. The mirror is located on the side of the lens system opposite to the beam splitter. The volumetric holographic optical element is located above the mirror.

Description

Technical Field

[0001] This disclosure relates to a display module. Prior Technology

[0002] Currently, head-up display (HUD) systems play a crucial role in enhancing driving safety and convenience. HUDs project information such as vehicle speed and navigation instructions into the driver's field of vision, reducing the need for the driver to take their eyes off the road. Most existing HUDs use a single imaging surface to present different information; however, this imaging method is prone to information overlap and visual confusion, and it cannot simultaneously display multi-layered distance information, thus affecting driving safety. Summary of the Invention

[0003] One of the technical features disclosed herein is a display module.

[0004] According to one embodiment of this disclosure, a display module includes a coherent light source, a beam splitter, a spatial light modulator, a lens system, a mirror, and a volumetric holographic optical element. The beam splitter is located above the coherent light source. The spatial light modulator is located on one side of the beam splitter and configured to modulate a plurality of light rays, each of which has an imaging plane different from the others. The lens system is located on the side of the beam splitter opposite to the spatial light modulator. The mirror is located on the side of the lens system opposite to the beam splitter. The volumetric holographic optical element is located above the mirror.

[0005] In one embodiment of this disclosure, the lens system includes a first lens, a second lens, and a filter. The first lens is located on the side of the beam splitter opposite to the spatial light modulator. The second lens is located on the side of the first lens opposite to the beam splitter. The filter is located between the first lens and the second lens.

[0006] In one embodiment of this disclosure, the filter is located on the focal plane between the first lens and the second lens.

[0007] In one embodiment of this disclosure, the distance between the spatial light modulator and the first lens is the focal length of the first lens.

[0008] In one embodiment of this disclosure, the lens system is a four-times focal length system configured to filter higher-order stray light from the light modulated by the spatial light modulator.

[0009] In one embodiment of this disclosure, the display module further includes a windshield. The windshield is located above and attached to the volumetric holographic optical element.

[0010] In one embodiment of this disclosure, the spatial light modulator includes a substrate, a lower electrode layer, a first alignment layer, a liquid crystal layer, a second alignment layer, an upper electrode layer, and an encapsulation layer. The lower electrode layer is located on the substrate. The first alignment layer is located on the lower electrode layer. The liquid crystal layer is located on the first alignment layer. The second alignment layer is located on the liquid crystal layer. The upper electrode layer is located on the second alignment layer. The encapsulation layer is located on the upper electrode layer.

[0011] In one embodiment of this disclosure, a mirror is configured to reflect a plurality of light rays emitted from the lens system onto a volumetric holographic optical element.

[0012] In one embodiment of this disclosure, the beam splitter is located between the lens system and the spatial light modulator.

[0013] In one embodiment of this disclosure, the lens system is located between the reflector and the beam splitter.

[0014] In the above-disclosed embodiments, since the spatial light modulator is configured to modulate a plurality of light rays, and each of the light rays has an imaging surface different from the others, the driver can see images with different imaging surfaces (i.e., different distances) on the windshield, which improves the information overlap and visual confusion caused by a single imaging surface and enhances driving safety. Simple Explanation of the Diagram

[0015] The nature of this disclosure can be best understood by reading it in conjunction with the accompanying illustrations and by the embodiments described below. Note that, according to standard practice in the industry, the various features are not drawn to scale. In fact, the dimensions of the various features may be increased or decreased arbitrarily for clarity of explanation. Figure 1 shows a side view of a display module according to an embodiment of the present disclosure. Figure 2 shows a partially enlarged cross-sectional view of the spatial light modulator in Figure 1. Figure 3 shows a side view of the lens system in Figure 1. Figure 4 shows a magnified side view of the area near the spatial light modulator in Figure 1. Implementation

[0016] The following disclosure of embodiments provides many different implementations, or examples, for carrying out different features of the provided object. Specific examples of elements and arrangements are described below to simplify the subject matter. Of course, these examples are merely illustrative and are not intended to be limiting. Furthermore, element symbols and / or letters may be repeated in various examples. This repetition is for simplicity and clarity and does not in itself specify the relationship between the various embodiments and / or configurations discussed.

[0017] Spatial relative terms such as “below,” “under,” “lower,” “above,” and “upper” are used herein for descriptive purposes to describe the relationship between one element or feature and another, as shown in the accompanying drawings. Spatial relative terms are intended to cover different orientations of the device in use or operation other than those shown in the accompanying drawings. The device may be oriented in other ways (rotated 90 degrees or otherwise), and the spatial relative descriptors used herein shall be interpreted accordingly.

[0018] Figure 1 illustrates a side view of a display module 100 according to an embodiment of the present disclosure. Referring to Figure 1, the display module 100 includes a coherent light source 110, a beam splitter 120, a spatial light modulator 130, a lens system 140, a reflector 150, and a volumetric holographic optical element 160. The beam splitter 120 is located above the coherent light source 110. The spatial light modulator 130 is located to one side of the beam splitter 120 and is configured to modulate a plurality of light rays L1, L2, each of which has an imaging plane different from the others. For example, the imaging position S1 of light ray L1 can be located at an infinite distance from the volumetric holographic optical element 160 (i.e., an infinite image distance), and the imaging position S2 of light ray L2 can be located at a distance of twenty meters from the volumetric holographic optical element 160. In Figure 1, a group of light rays (e.g., light ray L1) is illustrated as two light rays; however, this representation is only intended to illustrate the illumination range of light ray L1 and is not intended to limit the number of emitted light rays. Lens system 140 is located on one side of beam splitter 120 relative to spatial light modulator 130. Reflector 150 is located on one side of lens system 140 relative to beam splitter 120. Volumetric holographic optics 160 is located above reflector 150. Furthermore, display module 100 includes windshield 170. Windshield 170 is located above and fitted to volumetric holographic optics 160.

[0019] In this embodiment, the beam splitter 120 is located between the lens system 140 and the spatial light modulator 130. Furthermore, in this embodiment, the lens system 140 is located between the mirror 150 and the beam splitter 120. Additionally, the lower surface of both the volumetric holographic optical element 160 and the windshield 170 is curved. That is, the volumetric holographic optical element 160 has the function of compensating for the curvature of the lower surface of the windshield 170, making the lower surface of the volumetric holographic optical element 160 equivalent to a plane mirror. In practical applications, the curved volumetric holographic optical element 160 is formed by the interference of two plane waves, and during its formation, the volumetric holographic optical element 160 has the same overall shape as when it is completed, so that the curvature information of the volumetric holographic optical element 160 is written into the element.

[0020] Since the spatial light modulator 130 is configured to modulate multiple light rays L1 and L2, and each of the light rays L1 and L2 has an imaging surface different from the others, the driver can see images with different imaging surfaces (i.e., different distances) on the windshield 170, which improves the information overlap and visual confusion caused by a single imaging surface and enhances driving safety.

[0021] Figure 2 shows a partially enlarged cross-sectional view of the spatial light modulator 130 in Figure 1. Referring to Figure 2, the spatial light modulator 130 includes a substrate 132, a lower electrode layer 133, a first alignment layer 134, a liquid crystal layer 135, a second alignment layer 136, an upper electrode layer 137, and an encapsulation layer 138. The lower electrode layer 133 is located on the substrate 132. The first alignment layer 134 is located on the lower electrode layer 133. The liquid crystal layer 135 is located on the first alignment layer 134. The second alignment layer 136 is located on the liquid crystal layer 135. The upper electrode layer 137 is located on the second alignment layer 136. The encapsulation layer 138 is located on the upper electrode layer 137. The material of the substrate 132 may include glass, silicon, or any suitable transparent optical material. In this embodiment, a driving circuit is disposed on the substrate 132 of the spatial light modulator 130. The driving circuit is configured to control a plurality of pixels of the spatial light modulator 130 through the lower electrode layer 133 and the upper electrode layer 137. The first alignment layer 134 and the second alignment layer 136 have the same alignment direction and are configured to control the arrangement of liquid crystal polymers in the liquid crystal layer 135. The liquid crystal layer 135 contains a plurality of liquid crystal polymers and is configured to modulate the phase or amplitude of light L1. In practical applications, the driving circuit controls the arrangement direction of the liquid crystal polymers in the liquid crystal layer 135 through the lower electrode layer 133 and the upper electrode layer 137, thereby changing the refractive index of the liquid crystal layer 135 to modulate the phase or amplitude of light L1.

[0022] Figure 3 shows a side view of the lens system 140 in Figure 1. Referring to Figures 1 and 3, in this embodiment, the lens system 140 is a four-fold focal length system configured to filter higher-order stray light from the spatial light modulator 130, specifically light rays L1 and L2. The lens system 140 includes a first lens 142, a second lens 144, and a filter 146. The first lens 142 is located on one side of the beam splitter 120 relative to the spatial light modulator 130. The second lens 144 is located on one side of the first lens 142 relative to the beam splitter 120. The filter 146 is located between the first lens 142 and the second lens 144. Furthermore, the filter 146 is located on the focal plane between the first lens 142 and the second lens 144. In this embodiment, the first lens 142 is configured to receive light from the input surface I and perform a Fourier transform. The first lens 142 has a focal length f1, and the distance between the input surface I and the first lens 142 is equal to the focal length f1 of the first lens 142. Furthermore, the distance between filter 146 and first lens 142 is equal to the focal length f1 of first lens 142. This design allows first lens 142 to project light onto filter 146 (i.e., the focal plane of first lens 142) and convert it into a spectral distribution. Second lens 144 has a focal length f2. Second lens 144 is configured to receive the spectral information converted by first lens 142 and output the spectral information to output surface O after inverse Fourier transform. The distance between second lens 144 and output surface O is equal to the focal length f2 of second lens 144. Furthermore, the distance between second lens 144 and filter 146 is equal to the focal length f2 of second lens 144. Filter 146 has an opening 147, which is configured to allow partial light to pass through, thereby filtering high-order stray light generated by spatial light modulator 130. In some embodiments, filter 146 can be a baffle or a mask. In some embodiments, filter 146 contains light-absorbing or reflective material.

[0023] Figure 4 shows a partially enlarged side view of the vicinity of the spatial light modulator 130 in Figure 1. Referring to Figures 1 and 4, in some embodiments, the spatial light modulator 130 may be a phase modulator. In some embodiments, the spatial light modulator 130 may be an amplitude modulator. In some embodiments, the spatial light modulator 130 may be a combination of a phase modulator and an amplitude modulator. In some embodiments, the distance between the spatial light modulator 130 and the first lens 142 is the focal length f1 of the first lens 142. That is, the spatial light modulator 130 is located on the input surface I (see Figure 3) of the lens system 140. The spatial light modulator 130 is configured to calculate information about the input light. After calculating the wave function φ of the light, an Iterative Fourier Transform Algorithm (IFTA) is introduced to extract the pure phase data of the wave function φ. This is used by the phase modulator. The pure phase data u is then taken as its conjugate u*, and the two terms are added together to obtain the pure amplitude data, which is used by the amplitude modulator.

[0024] In this embodiment, the spatial light modulator 130 has a modulation capability A. According to the Nyquist-Shannon sampling theorem, when the side length of each pixel of the spatial light modulator 130 is d, the modulation capability A of the spatial light modulator 130 can be expressed by the following formula:

[0025] Where λ is the wavelength of the input light and f1 is the focal length of the first lens 142. Therefore, the size of the opening 147 of the filter 146 of the lens system 140 is the modulation capability A.

[0026] The foregoing outlines the features of several embodiments, enabling those skilled in the art to better understand the nature of this disclosure. Those skilled in the art should understand that they can readily use this disclosure as the basis for designing or modifying other processes and structures to achieve the same objectives and / or advantages as the embodiments described herein. Those skilled in the art should also recognize that such equivalent constructions do not depart from the spirit and scope of this disclosure, and that various changes, substitutions, and alterations can be made to them without departing from the spirit and scope of this disclosure.

[0027] 100: Display Module 110: Coherent Light Source 120: Beam Spectroscope 130: Spatial light modulator 132:Substrate 133: Lower electrode layer 134: First alignment layer 135: Liquid Crystal Layer 136: Second alignment layer 137: Upper electrode layer 138: Encapsulation layer 140: Lens System 142: First Lens 144: Second Lens 146: Filter 147: Opening 150: Reflector 160: Volumetric Holographic Optical Element 170: Windshield A: Modulation capability E: Observer f1, f2: Focal length I: Input surface O: Output surface L1, L2: Light rays S1, S2: Imaging positions

[0028] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A display module comprising: a co-modulated light source; a beam splitter located above the co-modulated light source; a spatial light modulator located on one side of the beam splitter; the spatial light modulator comprising: a substrate; a lower electrode layer located on the substrate; a first alignment layer located on the lower electrode layer; a liquid crystal layer located on the first alignment layer; a second alignment layer located on the liquid crystal layer; an upper electrode layer located on the second alignment layer; and an encapsulation layer located on the upper electrode layer; a lens system located on one side of the beam splitter relative to the spatial light modulator; the lens system comprising: a first lens located on one side of the beam splitter relative to the spatial light modulator; a second lens located on one side of the first lens relative to the beam splitter; and a filter located between the first lens and the second lens; a reflector located on one side of the lens system relative to the beam splitter; and a volumetric holographic optical element located above the reflector.

2. The display module as described in claim 1, wherein the filter is located on a focal plane between the first lens and the second lens.

3. The display module as claimed in claim 1, wherein a distance between the spatial light modulator and the first lens is the focal length of the first lens.

4. The display module as claimed in claim 1, wherein the lens system is a four-times focal length system configured to filter higher-order stray light from the light modulated by the spatial light modulator.

5. The display module as described in claim 1 further includes: a windshield located above and attached to the volumetric holographic optical element.

6. The display module as claimed in claim 1, wherein the reflector is configured to reflect a plurality of light rays emitted from the lens system onto the volumetric holographic optical element.

7. The display module as described in claim 1, wherein the beam splitter is located between the lens system and the spatial light modulator.

8. The display module as described in claim 1, wherein the lens system is located between the reflector and the beam splitter.

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