Holographic display device based on phase change material

Abstract

The present invention relates to a holographic display device based on phase change materials, which has the characteristics of high resolution, high frame rate, multi-level regulation, low energy consumption, etc. The holographic display technology includes a laser backlight source, a data processor, a multi-level phase change spatial light modulation unit array, and an optical system. The holographic display technology based on phase change materials of the present invention can be widely used in but not limited to the following devices: smart phones, computers, televisions, medical equipment, educational equipment, entertainment equipment, military equipment, and any other electronic equipment that requires visual display.

Description

Technical Field

[0001] The present invention belongs to the technical field of phase change materials, and more specifically, relates to a holographic display device based on phase change materials. Background Art

[0002] Holographic display technology is a 3D display technology that records and reproduces all the visual information of a 3D object through the physical phenomena of interference and diffraction, as well as the intensity and phase information of light. This technology can display a real 3D space effect, allowing viewers to see three-dimensional images without any auxiliary equipment, greatly enhancing the visual experience. Holographic display has potential applications in various industries, including medical, education, entertainment, design and other fields, and can be used for fine image presentation and complex data visualization.

[0003] Although holographic display technology has great potential, it still faces some technical bottlenecks. First, the existing holographic display technology has a low resolution and cannot meet the needs of users in terms of details. Second, the slow response speed affects the smoothness of user viewing and operation and reduces the user experience. The existence of these problems limits the widespread application of holographic display technology and hinders its further development in various fields.

[0004] Phase change materials are a type of material with reversible phase change properties that can achieve rapid light response through electric field stimulation. Compared with traditional liquid crystal materials, phase change materials have faster light response speed (nanosecond level) and smaller pixel size (nanometer level), so they have great potential in improving key performance indicators such as resolution and switching speed of holographic display technology.

[0005] However, there are also some problems in applying phase change materials to holographic displays. For example, the extinction coefficient of phase change materials is larger than that of liquid crystal materials, which leads to increased light loss in the light modulation process and reduces the transmission efficiency of light waves. The intermediate state of phase change materials is not easy to control, and each layer of phase change film usually has only two states, which limits the display effect in color and grayscale.

[0006] The present invention designs a multi-level controlled phase-change holographic display technology. Through the design of multi-layer phase-change light modulation layers and anti-reflection layers, the phase-change material can present more states, thereby realizing high-resolution, high-refresh rate, multi-level controlled holographic display. The application of this technology will greatly enhance the visual effect of holographic display, promote the development of holographic display technology, and broaden its application scope in various fields. Summary of the invention

[0007] The present invention provides a holographic display technology based on phase change materials, aiming to achieve a holographic display technology with high resolution, high refresh rate, multi-level regulation and efficient transmission.

[0008] The holographic display technology based on phase change materials mainly includes a laser backlight source, a data processor, a multi-level phase change spatial light modulation unit array, and an optical system; the laser backlight source is used to emit a monochromatic or multi-color laser beam, and is a light source for generating a desired holographic image by controlling the color, intensity and direction of the laser; the data processor includes an image analysis module and a data encoding module, the image analysis module is used to analyze the input image data, and the data encoding module converts the analyzed data into a control signal for controlling the phase change spatial light modulation unit array; the multi-level phase change spatial light modulation unit array includes a substrate, a multi-level phase change light modulation pixel unit array, a transmittance-enhancing layer, a light shielding layer, and a crossbar control structure; the optical system includes a group of lenses or reflectors and an optical adjustment module, which are used to receive and process the laser beam emitted by the phase change spatial light modulation unit array, and adjust the propagation path of the beam according to the characteristics of the holographic image (such as size, shape and distance), thereby generating a holographic image.

[0009] The laser backlight source includes a laser emitter capable of emitting monochromatic or polychromatic laser light and a beam splitter for separating the laser light from the laser emitter into a plurality of independent laser beams.

[0010] The multi-level phase change light modulation pixel unit array includes multiple phase change control layers. A common electrode is arranged between adjacent phase change material layers. Each phase change material layer can independently control its phase change state by applying voltage, thereby realizing multi-level control of the laser backlight source.

[0011] The side lengths of the phase change regions of the multiple phase change regulation layers are in the range of 0.5um to 100um, the total thickness of the multiple phase change layers is in the range of 20nm to 100nm, and the thickness of a single phase change layer is ≥5nm.

[0012] The structure of the anti-reflection layer is H(LH)x, where H is a high refractive index and low extinction coefficient thin film layer, L is a low refractive index and low extinction coefficient thin film layer, X is the number of film layer group periods, X≥1, and the optical thickness of each film layer is one quarter of the use wavelength.

[0013] The light shielding layer is made of black photoresist and is arranged in a staggered manner with the light modulation pixel unit array in a region to reduce the crosstalk of diffracted light.

[0014] The crossbar control structure includes a horizontal electrode layer composed of a plurality of horizontal electrodes and a vertical electrode layer composed of a plurality of vertical electrodes. The plurality of horizontal electrodes and the plurality of vertical electrodes form a crosspoint array, and there is a light modulation pixel unit in the middle of each crosspoint.

[0015] The optical system includes one or more lenses for adjusting the focus or direction of the laser backlight source, a polarizer for controlling the polarization state of the laser beam, and an optical adjustment module for automatically adjusting the working states of the lens, polarizer and spatial light modulator according to a control signal received from a data processor to optimize the quality of the holographic image.

[0016] Holographic display technology can be widely used in but not limited to the following devices: smartphones, computers, televisions, medical equipment, educational equipment, entertainment equipment, military equipment, and any other electronic device that requires visual display. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the structure of the holographic display device of the present invention;

[0018] Figure 2 It is a structural schematic diagram of a multi-level phase change modulation unit of the present invention;

[0019] Figure 3 Schematic diagram of the structure of the anti-reflection layer of the present invention;

[0020] Figure 4 is a schematic diagram of the crossbar control electrode structure of the present invention;

[0021] Figure numerals: 101 laser emitter, 102 beam splitter, 103 multi-level phase change spatial light modulation unit array, 104 optical system, 201 upper electrode, 202 phase change material layer, 203 common electrode, 204 phase change material layer, 205 lower electrode, 301 high refractive index and low extinction coefficient thin film layer, 302 low refractive index and low extinction coefficient thin film layer, 303 high refractive index and low extinction coefficient thin film layer. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] The present invention aims to provide a holographic display technology based on phase change materials, which has the characteristics of fast response speed, high resolution, multi-level regulation and high light utilization rate.

[0024] like Figure 1As shown, it is a schematic diagram of the structural distribution of the present invention, the laser emitter 101 emits monochromatic or multi-color laser, the beam splitter 102 separates the laser from the laser emitter into multiple independent laser beams, the multi-level phase change spatial light modulation unit array 103 modulates the phase or amplitude of the laser according to the information, and the optical system 104 is used to adjust the focus or direction of the laser.

[0025] The multi-level phase change spatial light modulation unit array 103 includes a substrate, a multi-level phase change light modulation pixel unit array, an anti-reflection layer, a light shielding layer, and a crossbar control structure;

[0026] The optical system 104 includes a group of lenses or reflectors and an optical adjustment module, which is used to receive and process the laser light beam emitted by the phase change spatial light modulation unit array, and adjust the propagation path of the light beam according to the characteristics of the holographic image (such as size, shape and distance), thereby generating a holographic image.

[0027] The holographic display device also includes the data processor, which includes an image parsing module and a data encoding module, the image parsing module is used to parse the input image data, and the data encoding module converts the parsed data into a control signal for controlling the phase change spatial light modulation unit array;

[0028] like Figure 2 As shown, it is a schematic diagram of the structure of the multi-level phase change modulation unit of the present invention. Phase change material layers 202 and 204 are sandwiched between the upper electrode 201 and the lower electrode 205, and a common electrode 203 is provided between adjacent phase change material layers. Each phase change material layer 202 and 204 can independently control its phase change state by applying voltage, thereby realizing multi-level regulation of the laser backlight source. The side length of the phase change region of the phase change regulation layer is in the range of 0.5um to 100um, the total thickness of multiple phase change layers is in the range of 20nm to 100nm, and the thickness of a single phase change layer is ≥5nm.

[0029] like Figure 3 As shown, it is a schematic diagram of the structure of the anti-reflection layer of the present invention; the structure of the anti-reflection layer is H(LH)x, wherein H is a high refractive index and low extinction coefficient thin film layer 301, 303, L is a low refractive index and low extinction coefficient thin film layer 302, X is the number of periods of the film layer group (X≥1), and the optical thickness of each film layer is one quarter of the working wavelength, which is used to improve the transmittance.

[0030] like Figure 4 The figure is a schematic diagram of the crossbar control electrode structure of the present invention; the crossbar control structure is a two-layer electrode layer, and the crossbar control structure is formed by a plurality of horizontal control electrodes and vertical electrodes to form a crosspoint array, and there is a light modulation pixel unit in the middle of each crosspoint.

[0031] The laser passes through the light modulation pixel unit, and the phase change material of the phase change material layer can be converted between a crystalline state and an amorphous state under electrical stimulation or laser stimulation, thereby changing the transmittance of the phase change layer. The two transparent electrode layers, i.e., the upper electrode 201 and the lower electrode 205, sandwiching the phase change material in the multi-level phase change modulation unit can control the crystallization state of the phase change material by applying voltage. Specifically, a pulse voltage or laser pulse of medium intensity is applied to the phase change material layer. Under the action of the current or laser pulse, the temperature of the phase change material rises to a temperature range above the crystallization temperature and below the melting temperature, and is maintained for a certain period of time. At this time, the lattice is orderly arranged to form a crystalline state, thereby realizing the transition from amorphous to crystalline state; a short and strong voltage or laser pulse is applied to the phase change material to raise the temperature of the phase change material to above the melting temperature, thereby destroying the long-range order of the crystalline state. The pulse falling edge is very short, resulting in the phase change material being quickly cooled to below the crystallization temperature, thereby fixing the phase change material in the amorphous state, thereby realizing the transition from the crystalline state to the amorphous state. The intensity of the spatial incident light is modulated by the change in transmittance of the phase change material of the phase change material layer when the amorphous state and the crystalline state are mutually transformed.

[0032] The phase change material of the phase change material layer may include the following chalcogenides and their alloys, including but not limited to: GST, GSST, IST, GeTe, SbTe, BiTe, InSb, InSe, GeSb, SbSe, GaSb, GaSb, GeSbTe, AgInSbTe, InSbTe, AgSbTe, Ag2In4Sb 76 Te 17 (AIST), in addition, the atomic percentage in the above chemical formulas can be variable. The phase change material layer may further include at least one dopant, such as C, N. Preferably, the phase change material is Sb2Te3. Under the same thickness, the transmittance change of Sb2Te3 before and after the phase change is the largest, and the phase change temperature of Sb2Te3 is low, the voltage or laser amplitude required for the transition is low, and the pulse width is narrow, which is convenient for reducing the energy consumption of the entire device and improving the response speed of the phase change material, thereby improving the image refresh rate of the device and showing a better effect.

[0033] The thickness of the phase change material layer is in the range of 20nm to 100nm. As the thickness of the phase change material layer increases, the transmittance of visible light decreases, and the temperature required for the crystallization of the phase change material increases, so the more suitable thickness is 30nm. The phase change material of the phase change material layer can be driven by laser or voltage. When driven by voltage, the transparent electrodes on both sides of the phase change layer apply voltage to cause the phase change material to undergo phase change.

[0034] The transmittance of the phase change layer of the phase change modulation unit varies greatly in different states. The phase change material is stable in the crystalline and amorphous states, so the voltage or laser can be removed when the phase change material is in a stable state, so the power consumption of the entire device is very low.

[0035] The phase change modulation unit switches between the crystalline and amorphous states very quickly, that is, the time required for a single pixel to change from dark to bright or from bright to dark is very short, about less than 100ns, which fully meets the requirements for device response speed in various scenarios.

[0036] The function of the anti-reflection layer is to solve the problem of weak energy of transmitted light caused by interface reflection and certain extinction coefficient of phase change materials. The transmitted light treated by the anti-reflection film can not only improve the transmittance, but also greatly reduce the energy of continuous reflection of light between components, thereby improving the utilization efficiency of spatial light. The low refractive index material of the anti-reflection layer may include the following materials, including but not limited to: SiO2, Al2O3, In2O3, MgF2; the high refractive index material of the anti-reflection layer may include the following materials, including but not limited to: ZnS, TiO2, etc.

[0037] The holographic display device can be widely used in but not limited to the following devices: smart phones, computers, televisions, medical equipment, educational equipment, entertainment equipment, military equipment and any other electronic devices that require visual display.

[0038] Through the above embodiments, we can see that this holographic display technology based on phase change materials has the characteristics of fast response speed, high resolution, multi-level regulation, high light utilization rate, etc., and can be used in a wide range of applications.

[0039] It is easy for those skilled in the art to understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A holographic display device based on phase change material, characterized in that: The device includes a laser light source, a data processor, a multi-level phase-change light modulation unit array, and an optical system; The laser backlight source is used to emit a monochromatic or polychromatic laser beam, and to generate a desired holographic image by controlling the color, intensity and direction of the laser. The data processor includes an image analysis module and a data encoding module, the image analysis module is used to analyze the input image data, and the data encoding module converts the analyzed data into a control signal for controlling the multi-level phase change light modulation unit array; The multi-level phase-change light modulation unit array comprises a substrate, a phase-change material layer, and a crossbar control structure; the multi-level phase-change light modulation unit array is used to modulate the phase or amplitude of the laser so that the phase-change material layer can realize the mutual conversion between the crystalline state and the amorphous state; The optical system is used to receive and process the laser beam emitted by the phase change light modulation unit array, and adjust the propagation path of the beam according to the characteristics of the holographic image, so as to generate a holographic image; The multi-level phase change light modulation unit array comprises a plurality of the phase change material layers, a common electrode is arranged between adjacent phase change material layers, and each phase change material layer can independently control its phase change state by applying a voltage, thereby realizing multi-level regulation of the laser light source; The multi-level phase change optical modulation unit array further includes an anti-reflection layer, the structure of the anti-reflection layer is H(LH)x, wherein H is a high refractive index and low extinction coefficient thin film layer, L is a low refractive index and low extinction coefficient thin film layer, X is the number of film layer group periods, X≥1, and the optical thickness of each film layer is one quarter of the use wavelength; The side lengths of the phase change regions of the phase change material layers are in the range of 0.5um to 100um, the total thickness of the phase change material layers is in the range of 20nm to 100nm, and the thickness of a single phase change material layer is ≥5nm; The crossbar control structure comprises a horizontal electrode layer composed of a plurality of horizontal electrodes and a vertical electrode layer composed of a plurality of vertical electrodes. The plurality of horizontal electrodes and the plurality of vertical electrodes form a cross point array, and there is a light modulation pixel unit in the middle of each cross point.

2. The holographic display device based on phase change material according to claim 1, characterized in that: The laser light source comprises a laser emitter capable of emitting monochromatic or polychromatic laser light and a beam splitter, wherein the beam splitter is used to separate the laser light from the laser emitter into a plurality of independent laser beams.

3. The holographic display device based on phase change material according to claim 1, characterized in that: The multi-level phase-change light modulation unit array further includes a light shielding layer, which is made of black photoresist and is arranged in a staggered manner with the light modulation unit array in terms of region, so as to reduce crosstalk of diffracted light.

4. The holographic display device based on phase change material according to claim 1, characterized in that: The optical system includes one or more lenses for adjusting the focus or direction of the laser, and a polarizer for controlling the polarization state of the laser beam. The optical system also includes an optical adjustment module for automatically adjusting the working state of the one or more lenses, the polarizer and the multi-level phase change light modulation unit array according to the control signal received from the data processor to optimize the quality of the holographic image.

5. A mobile terminal, characterized in that: The terminal comprises the holographic display device according to any one of claims 1-4.

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