Fourier beam shaper and display device comprising the same

Abstract

The present disclosure provides a Fourier beam shaper and a display device including the Fourier beam shaper. The Fourier beam shaper includes: a waveguide; an input coupler configured to direct a plurality of light beams to the interior of the waveguide in a time-sequential manner; and a space transformer configured to output the plurality of light beams traveling in the waveguide through spatially different regions of the space transformer.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2019-0081521, filed on Jul. 5, 2019, and Korean Patent Application No. 10-2020-0069848, filed on Jun. 9, 2020, the disclosures of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates to a Fourier beam shaper and a display device including the Fourier beam shaper. Background Art

[0004] Recently, with the development of electronic devices and display devices capable of realizing virtual reality (VR), people's interest in such devices has increased. As the next step of VR, technologies (methods) for realizing augmented reality (AR) and mixed reality (MR) have been studied.

[0005] Unlike VR, which is based on a completely virtual world, AR is a display technology that displays the real world together with virtual objects or information superimposed (combined) on the real world, thereby further increasing the effect of reality. Although VR is limited to applications such as games or virtual experiences, the advantage of AR is that it can be applied to various real-world environments. In particular, AR has attracted attention as a next-generation display technology suitable for ubiquitous environments or Internet of Things (IoT) environments. AR can be an example of MR because AR displays a mixture of the real world and additional information (virtual world).

[0006] This imaging system uses an optical system to project the generated image onto the user's eyes. Generally, the optical system uses a lens, and the imaging system basically requires a distance between the spatial light modulator and the lens and a distance between the lens and the user's eyes to project the image onto the user's eyes. However, this increases the size of the imaging system. Summary of the invention

[0007] Provided are a Fourier beam shaper and a display device including the Fourier beam shaper.

[0008] According to an aspect of the embodiment, a Fourier-beam shaper includes: a waveguide; an input coupler configured to direct a plurality of light beams to an interior of the waveguide; and a space converter configured to output the plurality of light beams travelling in the waveguide through spatially different regions of the space converter.

[0009] The space transformer may be configured to direct and output a plurality of light beams in specific directions, respectively.

[0010] The space transformer may be configured to direct and output at least two of the plurality of light beams in different directions.

[0011] The space converter may include a plurality of selective transmission elements arranged in a direction intersecting a direction in which the plurality of light beams are output, and each of the plurality of selective transmission elements may be configured to transmit one of the plurality of light beams to an external space and not transmit other light beams of the plurality of light beams to an external space.

[0012] Each of the plurality of selectively transmissive elements may be configured to selectively transmit the plurality of light beams according to an optical characteristic of the selectively transmissive element.

[0013] The optical properties may include diffractive properties.

[0014] At least two of the plurality of selective transmission elements may differ in at least one of grating structure and material.

[0015] Each of the plurality of selective transmission elements may be configured to selectively transmit or not transmit the plurality of light beams according to an electrical signal applied to the selective transmission element.

[0016] Multiple light beams can be incident on the input coupler at different angles of incidence.

[0017] The space transformer may be configured to output multiple light beams through spatially different regions of the space transformer based on an incident angle.

[0018] The space transformer may be configured to focus the plurality of light beams at different locations in the external space, respectively.

[0019] The outer space may be in the user's pupil.

[0020] Each of the plurality of light beams may be a partial image of a frame image.

[0021] Each of the plurality of light beams may be a pixel image of the frame image.

[0022] The sizes of the multiple light beams output from the space transformer may be different from the sizes of the multiple light beams incident on the input coupler.

[0023] The sizes of the multiple light beams output from the space transformer may be larger than the sizes of the multiple light beams incident on the input coupler.

[0024] The input coupler may include: a first input coupler configured to direct a first beam of the plurality of beam unit images into the interior of the waveguide; and a second input coupler configured to direct a second beam of the plurality of beam unit images into the interior of the waveguide.

[0025] The first light beam and the second light beam may be synchronized and incident on the first input coupler and the second input coupler, respectively, at the same time period.

[0026] The waveguide may include: a first waveguide in which the first light beam travels; and a second waveguide in which the second light beam travels.

[0027] The space converter may include: a first space converter, arranged on a first waveguide and configured to output a first light beam through different regions of the first space converter to form a first subframe image in an external space; and a second space converter, arranged on a second waveguide and configured to output a second light beam through different regions of the second space converter to form a second subframe image in an external space.

[0028] The first sub frame image and the second sub frame image may be formed in different areas of the external space.

[0029] The first sub-frame image and the second sub-frame image may be different parts of the frame image.

[0030] According to an aspect of the embodiments, a display device includes: a Fourier-beam shaper; and a light source configured to output a plurality of light beams to the Fourier-beam shaper.

[0031] The display device may further include an exit pupil expander configured to expand the plurality of light beams output from the Fourier-beam shaper.

[0032] The exit pupil expander can transmit light corresponding to the real environment.

[0033] The display device may further include a spatial light modulator configured to add image information to the plurality of light beams output from the Fourier-beam shaper or the light source.

[0034] The display device may further include a direction adjusting member configured to adjust incident angles of the plurality of light beams incident on the Fourier-beam shaper. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following description in conjunction with the accompanying drawings, in which:

[0036] Figure 1 is a schematic diagram showing a display device including a Fourier-beam shaper according to an embodiment;

[0037] Figure 2 It is shown Figure 1 A view of the structure of the Fourier-beam shaper shown in;

[0038] Figure 3 is a view showing an example of a selective transmission element of a space transformer according to an embodiment;

[0039] Figure 4 is a view showing a portion of a Fourier-beam shaper including a selective transmission element according to another embodiment;

[0040] Figure 5 is a view showing a method of selectively outputting a plurality of light beams through a plurality of selective transmission elements according to an embodiment;

[0041] Figure 6 is a view showing a display device according to another embodiment;

[0042] Figure 7 is a view showing a display device according to another embodiment;

[0043] Figure 8 is a view showing a display device according to another embodiment;

[0044] Fig. 9 is a view showing a portion of a display device according to another embodiment;

[0045] Fig.10 is a view showing a display device including a Fourier-beam shaper according to another embodiment;

[0046] Fig.11 is a schematic diagram showing a display device configured to add an image to Fourier transformed light according to another embodiment;

[0047] Fig.12 is a view showing a Fourier-beam shaper including a spatial light modulator according to an embodiment;

[0048] Fig.13 is a block diagram showing a display device according to another embodiment;

[0049] Fig.14 is a view showing an electronic device to which a display device is applied according to an embodiment; and

[0050] Fig.15 is a view illustrating an electronic device to which a display device is applied according to another embodiment. DETAILED DESCRIPTION

[0051] Reference will now be made in detail to embodiments, examples of which are shown in the accompanying drawings, wherein the same reference numerals refer to the same elements throughout. In this regard, the present embodiment may have different forms and should not be construed as being limited to the description set forth herein. Therefore, the embodiments are described below only by reference to the accompanying drawings to explain various aspects. As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items. Expressions such as "at least one of", when used after a list of elements, modify the entire list of elements without modifying a single element in the list.

[0052] In the following description, when an element is referred to as being “on another element” or “on another element,” it may be directly on the other element while being in contact with the other element, or may be over the other element without being in contact with the other element.

[0053] Unless otherwise stated, singular terms may include plural forms. It should also be understood that the terms "include" and / or "comprising" used herein specify the presence of stated features or elements, but do not preclude the presence or addition of one or more other features or elements.

[0054] An element referred to by a definite article or a demonstrative pronoun may be construed as referring to one or more of the element even if the element is in the singular.

[0055] Terms such as "first" and "second" may be used to describe various elements, but these elements should not be limited by these terms. These terms are only used to distinguish one element from another element.

[0056] Figure 1 is a schematic diagram showing a display device 10 including a Fourier beam shaper according to an embodiment, Figure 2 It is shown Figure 1 A diagram showing the structure of the Fourier beam shaper 200 is shown. Figure 1 The display device 10 may include: a beam output device 100 that outputs a plurality of beams; a Fourier-beam shaper 200 that receives the beams and outputs the beams through spatially different regions; and a processor 300 that controls the beam output device 100 and / or the Fourier-beam shaper 200 to display an image.

[0057] The light beam output device 100 may output a plurality of light beams in a time sequence. Here, each light beam may correspond to a partial image of a frame image. For example, the light beam corresponds to a pixel image of a frame image, or may correspond to the sum of a plurality of pixel images included in the frame image. The light beam may be light in which different frequencies are mixed. For example, the light beam may be light in which red light, green light, and blue light are mixed.

[0058] The light beam output device 100 may include a light source 110 and a spatial light modulator 130. The light source 110 may provide coherent light. The light source 110 may include a laser diode. However, light having a certain degree of spatial coherence may be diffracted and modulated by the spatial light modulator 130 so that the light may have coherence, and thus another light source may be used as long as the light source can emit light having a certain degree of spatial coherence.

[0059] The light source 110 may include a plurality of light sources that output light having different wavelengths. For example, the light source 110 may include a first light source that outputs light in a first wavelength band, a second light source that outputs light in a second wavelength band different from the first wavelength band, and a third light source that outputs light in a third wavelength band different from the first wavelength band and the second wavelength band. The first wavelength band, the second wavelength band, and the third wavelength band may correspond to red light, green light, and blue light, respectively.

[0060] The spatial light modulator 130 may output light having image information by modulating the light output from the light source 110 under the control of the processor 300. The resolution of the modulated light may be determined by the spatial resolution of the spatial light modulator 130. For example, when the spatial light modulator 130 is constructed by one pixel, the modulated light corresponds to a pixel image. Alternatively, when the spatial resolution of the spatial light modulator 130 is 2*2, the resolution of the modulated light may also be 2*2. The spatial light modulator 130 may output light corresponding to a 2D image, a 3D image, or a holographic image having different depth information.

[0061] The spatial light modulator 130 may be an amplitude modulation spatial light modulator, a phase modulation spatial light modulator, or a composite spatial light modulator that modulates both amplitude and phase. In addition, the spatial light modulator 120 may be a transmissive light modulator, a reflective light modulator, or a transflective light modulator. For example, the spatial light modulator 130 may include a liquid crystal on silicon (LCoS) panel, a liquid crystal display (LCD) panel, a digital light projection (DLP) panel, an organic light emitting diode (OLED) panel, or a micro-organic light emitting diode (M-OLED) panel. Here, the DLP panel may include a digital micromirror device (DMD).

[0062] The light beam output device 100 may further include a direction adjusting member 150 that changes the travel path of light output from the spatial light modulator 130 so that the light can be incident on the Fourier-beam shaper 200 at a given angle. The direction adjusting member 150 may be an actuator for adjusting the position of the spatial light modulator 130 to change the travel path of light, or may be an optical device for directly changing the travel path of light output from the spatial light modulator 130. The optical device may be an active optical device capable of variously adjusting the travel path of light under the control of the processor 300.

[0063] Until a plurality of light beams corresponding to one frame image are output, the direction adjusting member 150 can adjust the travel path of the light beam so that the light beam can advance in different travel paths. For example, when the resolution of the light beam is 2*2 and the resolution of the frame image is 20*20, the direction adjusting member 150 can control 100 light beams so that the 100 light beams can advance in 100 different travel paths.

[0064] The processor 300 may control the light beam output device 100 to output light. The output cycle of light may be determined based on the resolution of the frame image to be formed, the resolution of the light modulated by the spatial light modulator 130, and the frame time. For example, when the frame time is 1 / 60 seconds and the resolution of the light at the spatial light modulator 130 is 1 / 10 of the resolution of the frame image, the processor 300 may control the light beam output device 100 so that light may be output at a cycle of 1 / (60*10) seconds.

[0065] refer to Figure 1 , it is described that the spatial light modulator 130 outputs light having image information by modulating light, but the embodiment is not limited thereto. For example, the light source 110 may output light having image information under the control of the processor 300. In this case, the spatial light modulator 130 may not be used, and the direction adjustment member 150 may be an actuator for controlling the position of the light source 110, or an optical device for adjusting the travel path of the light output from the light source 110.

[0066] The Fourier-beam shaper 200 may receive a plurality of light beams from the light beam output device 100, and may output the light beams through different regions thereof to form a frame image in an external space. Figure 2 The Fourier-beam shaper 200 may include a waveguide 210, an input coupler 220 that guides a plurality of light beams into the interior of the waveguide 210, and a space transformer 230 that is configured such that the light beams traveling in the waveguide 210 may be output through spatially different regions of the space transformer 230.

[0067] The waveguide 210 may include a transparent member such as a glass material or a transparent plastic material, so that when the light beam travels in the waveguide 210 by total reflection, the size of the light beam incident on the waveguide 210 may vary. Therefore, the size of the light beam incident on the input coupler 220 may be different from the size of the light beam output through the space transformer 230. The light output from the light beam output device 100 may be a dot-type light, but the light traveling in the waveguide 210 may be a surface-type light because the light beam size increases while being repeatedly totally reflected in the waveguide 210. In addition, the light is uniformly distributed while traveling in the waveguide 210. Therefore, the size of the light beam output through the space transformer 230 may be larger than the size of the light beam incident on the input coupler 220.

[0068] The input coupler 220 may be arranged in the region of the waveguide 210. The input coupler 220 is shown as being located at an edge portion of the upper surface of the waveguide 210, but is not limited thereto. Alternatively, the input coupler 220 may be arranged in the lower region of the waveguide 210. The input coupler 220 may include a diffraction member BD that diffracts and transmits light incident on the input coupler 220. For example, the input coupler 220 may include a grating structure. The input coupler 220 may have diffraction characteristics to diffract and transmit incident light regardless of the incident angle of the incident light.

[0069] The space transformer 230 may include a plurality of selective transmission elements ST so that a plurality of light beams traveling in the waveguide 210 may be output through spatially different regions of the space transformer 230. The selective transmission elements ST may be two-dimensionally arranged on the waveguide 210. The selective transmission elements ST may be arranged continuously or discontinuously.

[0070] Each of the selective transmission elements ST can transmit one of the multiple light beams to the outside, and can block other light beams in the light beams. Each of the selective transmission elements ST can transmit or not transmit light according to its optical characteristics. For example, each of the selective transmission elements ST can transmit or not transmit light according to its diffraction characteristics. Alternatively, each of the selective transmission elements ST can transmit or not transmit light when its optical characteristics are changed by an electrical signal.

[0071] Each of the plurality of selective transmission elements ST may direct light in a specific direction and output light. For example, when light passes through the selective transmission element ST, at least two of the selective transmission elements ST may direct and output light in different directions. The degree of directionality of the selective transmission element ST may be determined by the optical characteristics of the selective transmission element ST (such as diffraction characteristics), and the optical characteristics of the selective transmission element ST may be changed by an electrical signal.

[0072] The time required for the spatial converter 230 to output all the multiple beams forming the frame image may be equal to the output period of the frame image, i.e., the frame time. For example, the beam output device 100 may output n beams corresponding to one frame image at intervals of 1 / n of the frame time. Each of the multiple selective transmission elements ST may direct and output one of the n beams. When all n beams are output, the user may recognize the frame image. Since the n beams are formed in different areas of the external space (e.g., the pupil E of the user), the user may recognize the n beams as one image.

[0073] In a structure in which a frame image of the same phase is incident on a waveguide, the distance between the waveguide and the beam output device may need to be equal to or greater than a certain value. However, since the Fourier-beam shaper 200 independently receives light and outputs light, the distance between the beam output device 100 and the Fourier-beam shaper 200 is not limited. This makes it possible to reduce the distance between the beam output device 100 and the Fourier-beam shaper 200. In addition, since the Fourier-beam shaper 200 forms a frame image by outputting a plurality of beams through different regions of the Fourier-beam shaper 200, the display device 10 can simply display the frame image by outputting the beam using the beam output device 100. Therefore, the light source 110 and the spatial light modulator 130 included in the beam output device 100 can have a small size. In addition, since each of the selective transmission elements ST of the Fourier-beam shaper 200 directs light in a specific direction, an additional optical device such as a lens may not be required. Therefore, the display device 10 can have a simple structure.

[0074] Figure 3 2 is a view showing an example of a selective transmission element ST of the space transformer 230 according to an embodiment. Figure 3 As shown, the selective transmission element ST may include a diffraction member having a grating structure. Each of the selective transmission elements ST may have a grating G having a varying shape, pitch (p), height (h), direction (d), material, etc. Therefore, the diffraction efficiency of each of the selective transmission elements ST may vary according to the incident angle of light. Figure 3 In FIG. 1 , the gratings G of the selective transmission element ST have different directions, but the embodiment is not limited thereto.

[0075] For example, the diffraction efficiency of each of the selective transmission elements ST may be equal to or greater than a first reference value of light incident at a specific incident angle, and may be less than a second reference value of light incident at other incident angles. Here, the second reference value may be equal to or less than the first reference value. Therefore, each of the selective transmission elements ST in the space transformer 230 may diffract and transmit light incident at a specific incident angle, but may totally reflect light incident at a different angle from the specific incident angle to the waveguide 210. Because the selective transmission element ST is capable of selectively diffracting and transmitting a plurality of light beams, the space transformer 230 may output light through different regions thereof.

[0076] When transmitting light, each of the selective transmission elements ST can output light in a specific direction. The degree of directionality of each of the selective transmission elements ST can be determined by the incident angle of light, the diffraction characteristics of the selective transmission element ST (such as the grating structure of the selective transmission element ST), or the material of the selective transmission element ST.

[0077] Although it is mentioned that the diffraction characteristics of each of the selective transmission elements ST depend on factors such as the material, shape, pitch (p), height (h), or direction (d) of the grating (G) of the selective transmission element ST, the selective transmission element ST is not limited thereto. For example, the diffraction characteristics of the selective transmission element ST may be changed by an electrical signal applied to the selective transmission element ST.

[0078] Figure 4 FIG. 1 is a view showing a portion of a Fourier beam shaper including a selective transmission element according to another embodiment. Figure 4 As shown, the spatial transformer 230 of the Fourier-beam shaper may include: an output coupler 231 disposed on the waveguide 210 and a selective transmission element ST disposed on the output coupler 231. The output coupler 231 may include a grating structure that diffracts and transmits light.

[0079] The transmittance of each of the selective transmission elements ST can be changed according to the electrical signal applied thereto. Each of the selective transmission elements ST may include: a base layer 232; a plurality of electro-optic particles 233 dispersed in the base layer 232 and having optical properties that change according to the electrical signal applied thereto for controlling the transmittance; and an electrode portion 234 for applying an electrical signal to the electro-optic particles 233.

[0080] The base layer 232 may include a transparent polymer material. For example, the base layer 232 may include a transparent curable resin.

[0081] Electro-optic particles 233 may include materials having an electro-optic effect. The electro-optic effect refers to a phenomenon in which optical properties change according to an electric field, and properties of electro-optic particles 233 (such as refractive index, phase delay or polarization properties) may change depending on the presence and / or intensity of an electric field.

[0082] The electro-optic particles 233 may include liquid crystal. At least one of the refractive index and polarization characteristics of the liquid crystal may change according to the presence of an electric field and / or the intensity of the electric field. For example, the electro-optic particles 233 may include polymer dispersed liquid crystal (PDLC), polymer network liquid crystal (PNLC), cholesteric liquid crystal, smectic liquid crystal, etc.

[0083] When an electric field is applied to the base layer 232, the electro-optic particles 233 may refract the incident light equally, so the electro-optic particles 233 may be transparent. Therefore, the electro-optic particles 233 may transmit the incident light. That is, when an electric signal is applied to the selective transmission element ST, the selective transmission element ST enters the transmission mode and transmits light.

[0084] On the contrary, when no electric field is applied to the base layer 232, the electro-optical particles 233 refract the incident light in different directions using different refractive indices according to the position of the incident light, so the electro-optical particles 233 may be opaque. Therefore, the electro-optical particles 233 scatter the incident light without transmitting the incident light. That is, when no electric signal is applied to the selective transmission element ST, the selective transmission element ST enters the non-transmission mode and does not transmit light.

[0085] In another example, when an electric field is applied to electro-optical particle 233, electro-optical particle 233 may enter a non-transmission mode, in which electro-optical particle 233 refracts light in different directions using different refractive indices depending on the position of the light, and when no electric field is applied to electro-optical particle 233, electro-optical particle 233 may enter a transmission mode, in which electro-optical particle 233 refracts light equally.

[0086] Therefore, according to the electrical signal applied to the selective transmission element ST, one of the selective transmission elements ST can enter the transmission mode to output the light diffracted from the output coupler 231, and the other selective transmission elements ST can enter the non-transmission mode to not output the light diffracted from the output coupler 231. The electrical signal can be synchronized with the light output from the light beam output device 100, and the selective transmission element ST can selectively transmit the light. Therefore, the space transformer 230 can output light through its spatially different regions.

[0087] Figure 52 is a view showing a method of selectively outputting a plurality of light beams through a plurality of selective transmission elements ST according to an embodiment. Figure 5 As shown, light may be incident on the input coupler 220 at a certain incident angle. The input coupler 220 diffracts the light and transmits the light to the waveguide 210. When traveling in the waveguide 210, the light may pass through one of the selective transmission elements ST that meets certain conditions, but may not pass through other selective transmission elements ST among the selective transmission elements ST.

[0088] For example, when the selective transmission element ST is composed of diffraction members having different diffraction characteristics, the selective transmission element ST having a low diffraction efficiency relative to the incident angle of the light may totally reflect the incident light into the waveguide 210, and the selective transmission element ST having a high diffraction efficiency relative to the incident angle of the light may diffract and transmit the incident light. Therefore, the light may be output to the outside only through the selective transmission element ST. For example, when the light beam L1 is incident at a first incident angle θ1, the first selective transmission element ST1 having a high diffraction efficiency may diffract and transmit the light beam L1, but the other selective transmission elements ST may totally reflect the light beam L1 into the waveguide 210. For example, when the light beam L2 is incident at a second incident angle θ2, the second selective transmission element ST2 having a high diffraction efficiency may diffract and transmit the light beam L2, but the other selective transmission elements ST may totally reflect the light beam L2 into the waveguide 210.

[0089] Alternatively, when the selective transmission element ST includes the electro-optical particles 233 whose optical characteristics are changed by an electric signal applied thereto, the selective transmission element ST brought into the transmission mode by the electric signal may transmit the incident light, while the selective transmission element ST brought into the non-transmission mode by the electric signal may not transmit the incident light. Therefore, light can be output to the outside only through the selective transmission element ST in the transmission mode.

[0090] For example, the light beam L1 incident at the first incident angle θ1 may pass through the first selective transmission element ST1 in the transmission mode, but may be scattered or totally reflected by the other selective transmission elements ST in the non-transmission mode into the waveguide 210. In addition, the light beam L2 incident at the second incident angle θ2 may pass through the second selective transmission element ST2 in the transmission mode, but may be scattered or totally reflected by the other selective transmission elements ST in the non-transmission mode into the waveguide 210.

[0091] Figure 6 1 is a view showing a display device 10a according to another embodiment. Figure 1 and Figure 6 , Figure 6The display device 10a shown may further include an exit pupil expander 400. The exit pupil expander 400 may expand light output from the Fourier beam shaper 200 in one direction (eg, the x-axis direction). Figure 6 Although not shown in the figure, the exit pupil expander 400 may include a waveguide, an input coupler, and an output coupler. The input coupler and the output coupler of the exit pupil expander 400 may also include a diffraction member. However, the input coupler and the output coupler of the exit pupil expander 400 may have diffraction characteristics for diffracting and transmitting light regardless of the incident angle of the light.

[0092] In addition, the exit pupil expander 400 may include a transparent material so that light corresponding to the real environment R, for example, light reflected or generated in the real environment R, may be transmitted to the pupil E of the user through the exit pupil expander 400. Therefore, the user may simultaneously recognize a frame image formed by the Fourier-beam shaper 200 and the real environment R. However, this is a non-limiting example. The exit pupil expander 400 may direct only the light output from the Fourier-beam shaper 200 to the pupil E of the user.

[0093] Using a single beam output device 100 and a single Fourier-beam shaper 200, as many beams as the number of selective transmission elements ST may be required to form one frame image. In addition, as the number of beams increases, the output period of the beams decreases. This may increase the signal processing load of the processor 300.

[0094] In some embodiments, the display apparatus may use multiple beam output devices and multiple Fourier-beam shapers to form a frame image.

[0095] Figure 7 is a view showing a display device 10 b according to another embodiment. Figure 7 The display device 10b shown may include a plurality of beam output devices 101 and a plurality of Fourier-beam shapers 201. Each of the beam output devices 101 may output a plurality of beams to the corresponding Fourier-beam shaper 201, and one frame image may be formed by the plurality of beams output from the Fourier-beam shaper 201.

[0096] Each of the light beam output devices 101 may include a light source, a spatial light modulator, and a direction adjustment member, but is not limited thereto. Figure 1 The descriptions are basically the same, so their detailed descriptions will be omitted.

[0097] Each of the Fourier-beam shapers 201 may further include a waveguide 211, an input coupler 221, and a space transformer 231. The input coupler 221 may be a diffraction member arranged in a region of the waveguide 211 to diffract and transmit incident light. For example, the input coupler 221 may have a grating structure and may have diffraction characteristics for diffracting and transmitting incident light regardless of the incident angle of the incident light.

[0098] The space transformer 231 may include a plurality of selective transmission elements ST so that a plurality of traveling light beams may be output through spatially different regions of the space transformer 231. The selective transmission elements ST may be arranged one-dimensionally on the waveguide 210. However, this is a non-limiting example. Alternatively, the selective transmission elements ST may be arranged two-dimensionally.

[0099] The selective transmission element ST may have different optical characteristics, so that light satisfying a certain condition may only pass through the selective transmission element ST, and light not satisfying the condition may not pass through the selective transmission element ST. The optical characteristics of the selective transmission element ST may be determined during the manufacturing process of the selective transmission element ST, or may be changed according to an electrical signal applied to the selective transmission element ST.

[0100] For example, the selective transmission element ST may have a diffraction characteristic. Each of the selective transmission elements ST may diffract and transmit light incident at a specific incident angle, but may totally reflect light incident at a different incident angle into the waveguide 211. Since the selective transmission element ST is capable of selectively diffracting and transmitting a plurality of light beams, the space transformer 231 may output light through different regions thereof.

[0101] Alternatively, the selective transmission element ST may include electro-optical particles 233 whose optical properties are changed by an electrical signal applied thereto. Each of the selective transmission elements ST may transmit incident light in a transmission mode, and may scatter or totally reflect the incident light into the waveguide 211 in a non-transmission mode.

[0102] In addition, each of the selective transmission elements ST can direct light in a specific direction while transmitting light. Therefore, the plurality of light beams output from the space converter 231 can form a frame image in the external space. The external space can be a space within the pupil E of the user.

[0103] Each of the beam output devices 101 may output a plurality of beams to the corresponding Fourier-beam shaper 201. The beam output devices 101 may be synchronized so as to output a plurality of beams at the same time period, and the Fourier-beam shaper 201 may output a plurality of beams at the same time period, thereby forming one frame image. For example, each of the Fourier-beam shapers 201 may form a line frame image by outputting light through different regions thereof, and one frame may be formed by the line frame images respectively formed by the Fourier-beam shapers 201.

[0104] Each of the beam output devices 101 can output as many beams as the number of the selective transmission elements ST of the corresponding Fourier-beam shaper 201, and one frame can be formed by a plurality of beams output from the Fourier-beam shaper 201. Therefore, the output cycle of the beam can be increased. Therefore, the load of the processor 300 can be reduced.

[0105] Figure 8 is a view showing a display device 10 c according to another embodiment. Figure 8 The display device 10c may include: a first light beam output device 102 and a second light beam output device 103, each of which outputs a plurality of light beams; a first Fourier-beam shaper 202 and a second Fourier-beam shaper 203, each of which forms a half-frame image using the light beam. Since each of the first Fourier-beam shaper 202 and the second Fourier-beam shaper 203 forms a half-frame image to form one frame image, the output period of the light beam can be increased compared to the case where one light source and one Fourier-beam shaper are used to form one frame image.

[0106] refer to Figure 7 and Figure 8 , it is described that each of the Fourier-beam shapers 201, 202, and 203 forms a partial image of a frame image, such as a line frame image or a half frame image. However, this is a non-limiting example. The Fourier-beam shaper and the beam output device may be combined differently to form a partial image. For example, one frame image may be formed by a quarter frame image formed by four beam output devices and four Fourier-beam shapers.

[0107] Figure 8 The display device 10c shown may further include an exit pupil expander 400. The exit pupil expander 400 may expand the light beam output from the first Fourier-beam shaper 202 and the light beam output from the second Fourier-beam shaper 203.

[0108] Fig. 9 1 is a view showing a portion of a display device 10d according to another embodiment. Fig. 9, the first waveguide 212 of the first Fourier-beam shaper 202a and the second waveguide 213 of the second Fourier-beam shaper 203a may partially overlap each other in a direction (e.g., in the Y-axis direction) perpendicular to the length directions of the first waveguide 212 and the second waveguide 213. As the lengths of the first waveguide 212 and the second waveguide 213 increase, uniformity of light traveling in the first waveguide 212 and the second waveguide 213 may increase.

[0109] Fig.10 2 is a diagram showing a display device 10e including a Fourier beam shaper 200b according to another embodiment. Fig.10 As shown, the beam output device 100b may include a light source 110, a waveguide 160, and a spatial light modulator 130b. The beam output device 100b may output light corresponding to a frame image by using the waveguide 160 and the spatial light modulator 130b. The Fourier-beam shaper 200b may include a plurality of selective transmission elements ST. The selective transmission elements ST may have different directivities according to the regions where the selective transmission elements ST are located, and thus may direct incident light in different directions. Even when the beam output device 100b outputs a frame image, the selective transmission elements ST of the Fourier-beam shaper 200b may transmit light while directing the light in a specific direction according to the optical characteristics of the selective transmission elements ST. Therefore, a frame image may be formed in an external space.

[0110] In the above description, it is assumed that light having image information is incident on the Fourier-beam shaper, but the embodiment is not limited thereto. For example, the image information may be added to the light output from the Fourier-beam shaper, or the Fourier-beam shaper may include a spatial light modulator configured to add the image information.

[0111] Fig.11 is a schematic diagram showing a display device 10f configured to add an image to Fourier transformed light according to another embodiment. Fig.11 As shown, the Fourier-beam shaper 200 can output multiple light beams received from the light source 110 as spatially separated light beams, i.e., Fourier-transformed light beams. The Fourier-beam shaper 200 may include a waveguide, an input coupler configured to direct the multiple light beams into the waveguide, and a space converter configured so that the light beams traveling in the waveguide can be output through different regions of the space converter. The space converter may include a plurality of selective transmission elements so that the light beams traveling in the waveguide can be output through spatially different regions of the space converter. The selective transmission elements may be arranged continuously or discontinuously.

[0112] Each of the selective transmission elements may transmit one of the light beams to the outside according to the optical characteristics of the selective transmission element, and may block the other light beams in the light beam. The selective transmission element may include a plurality of diffraction members having different diffraction characteristics, or may include a plurality of optical particles whose optical characteristics are variable according to an electrical signal. The structure of the Fourier-beam shaper 200 is substantially the same as described above, and thus a detailed description thereof will be omitted.

[0113] The light emitted from the light source 110 may not have image information, and the Fourier-beam shaper 200 may output the light without image information to a different space. In addition, the spatial light modulator 130c may add image information to the light output from the Fourier-beam shaper 200. The light output from the Fourier-beam shaper 200 is temporally and spatially separated light, and thus the spatial light modulator 130c may add image information to the temporally and spatially separated light incident thereon. Since the light beam output from the spatial light modulator 130c is a temporally and spatially separated sub-image, Fig.11 The display device 10f can provide a frame image by focusing the sub-image.

[0114] Fig.12 1 is a diagram showing a Fourier-beam shaper 200a including a spatial light modulator 130d according to an embodiment. Fig.12 As shown, the Fourier-beam shaper 200a includes: a waveguide 210a and a space converter 230a separated from each other; and a spatial light modulator 130d arranged between the waveguide 210a and the space converter 230a. An input coupler 211a onto which light is incident from a light source (not shown) may be arranged on the waveguide 210a, and an output coupler 231a through which light traveling in the waveguide 210a is output to the spatial light modulator 130d may be arranged on the waveguide 210a.

[0115] The light output from the waveguide 210a may be modulated by the spatial light modulator 130d to have image information. The light having the image information, i.e., the image light, is incident on the space converter 230a. The selective transmission element included in the space converter 230a may transmit a specific light beam according to the optical characteristics of the selective transmission element, and may block other light beams. The optical characteristics of the selective transmission element may change according to the electrical signal applied thereto, or may not change. The optical characteristics may be diffraction characteristics, scattering characteristics, reflection characteristics, refraction characteristics, etc.

[0116] According to an embodiment, the display apparatus may be implemented as a single hardware device or a combination of multiple hardware devices. For example, the display apparatus may include: a slave device including a light source unit and an optical scanner; and a master device including a processor.

[0117] Fig.13 is a block diagram showing a display device 10g according to another embodiment. Fig.13 , the display device 10g may include: a slave device S, which includes a beam output device 100, a Fourier-beam shaper 200, and a first communication unit 510; and a master device M, which includes a second communication unit 520 and a processor 300. The beam output device 100 and the Fourier-beam shaper 200 have the same structure as described above, so their detailed description will be omitted. The slave device S may be implemented as a wearable device such as a head-mounted display device, and the master device M may be an electronic device such as a cellular phone or a computer separate from the wearable device.

[0118] The first communication unit 510 and the second communication unit 520 may provide a control command of the processor 300 to the beam output device 100 and the Fourier-beam shaper 200. The first communication unit 510 and the second communication unit 520 may include a short-range wireless communication unit, a mobile communication unit, and the like.

[0119] The method of controlling the beam output device 100 and the Fourier-beam shaper 200 by using the processor 300 may be implemented as a software program including instructions stored in a computer-readable storage medium. The computer may read the instructions from the storage medium and may perform operations based on the read instructions according to the embodiment, and may include the display device of any one of the above-described embodiments.

[0120] Despite Figures 11 to 13 Not shown, but the exit pupil expander can be arranged to expand light corresponding to the image in one direction.

[0121] Each of the display devices 10, 10a, 10b, 10c, 10d, 10e, 10f, and 10g and the Fourier-beam shapers 200 and 200a can be used as a component of a wearable device. For example, the display devices 10, 10a, 10b, 10c, 10d, 10e, 10f, and 10g can be applied to a head mounted display (HMD). In addition, the display devices 10, 10a, 10b, 10c, 10d, 10e, 10f, and 10g can be applied to a glasses type display or a goggle type display. The wearable electronic device can operate in an interactive relationship with a smartphone (or connected to a smartphone). Fig.14 and Fig.15 is a view showing an electronic device to which the display device of the embodiment can be applied.

[0122] Although the Fourier beam shaper and the display device including the same have been described according to the embodiments with reference to the accompanying drawings, they are described only for illustrative purposes, and a person skilled in the art will appreciate that various changes and other equivalent embodiments may be made thereto.

[0123] It should be understood that the embodiments described herein should be considered only as descriptive and not for limiting purposes. The description of features or aspects in each embodiment should generally be considered as applicable to other similar features or aspects in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope defined by the appended claims.

Claims

1. A Fourier beam shaper, comprising: A waveguide comprising: a first waveguide in which the first light beam travels and a second waveguide in which the second light beam travels; an input coupler configured to direct a plurality of light beams into the interior of the waveguide, and comprising: a first input coupler configured to direct a first light beam of the plurality of light beams into the interior of the waveguide in a time-sequential manner, and a second input coupler configured to direct a second light beam of the plurality of light beams into the interior of the waveguide in a time-sequential manner; and a space converter configured to output a plurality of light beams traveling in the waveguide through spatially different regions of the space converter, and comprising: a first space converter disposed on the first waveguide and configured to temporally output a first light beam through different regions of the first space converter to form a first subframe image in an external space, and a second space converter disposed on the second waveguide and configured to temporally output a second light beam through different regions of the second space converter to form a second subframe image in an external space; wherein each of the plurality of light beams is a partial image of a frame image, The first waveguide and the second waveguide partially overlap with each other in a direction perpendicular to the length direction of the first waveguide and the second waveguide, the first input coupler and the second input coupler do not overlap with each other in a direction perpendicular to the length direction of the first waveguide and the second waveguide, and the first space transformer and the second space transformer do not overlap with each other in a direction perpendicular to the length direction of the first waveguide and the second waveguide.

2. The Fourier beam shaper according to claim 1, wherein: The space transformer is configured to direct and output the plurality of light beams in specific directions, respectively.

3. The Fourier beam shaper according to claim 1, wherein: The space transformer is configured to direct and output at least two of the plurality of light beams in different directions.

4. The Fourier beam shaper according to claim 1, wherein: The space converter includes a plurality of selective transmission elements, which are arranged in a direction intersecting a direction in which the plurality of light beams are output, and each of the plurality of selective transmission elements is configured to transmit one of the plurality of light beams to an external space and not to transmit other light beams of the plurality of light beams to an external space.

5. The Fourier beam shaper according to claim 4, wherein: Each of the plurality of selectively transmissive elements is configured to selectively transmit the plurality of light beams according to an optical characteristic of the selectively transmissive element.

6. The Fourier beam shaper according to claim 5, wherein: The optical properties include diffraction properties.

7. The Fourier beam shaper according to claim 5, wherein: At least two of the plurality of selective transmission elements differ in at least one of grating structure and material.

8. The Fourier beam shaper according to claim 5, wherein: Each of the plurality of selective transmission elements is configured to selectively transmit or not transmit the plurality of light beams according to an electrical signal applied to the selective transmission element.

9. The Fourier beam shaper according to claim 1, wherein: The multiple light beams are incident on the input coupler at different incident angles.

10. The Fourier beam shaper according to claim 9, wherein: The space converter is configured to output the plurality of light beams through spatially different regions of the space converter based on the incident angle.

11. The Fourier beam shaper according to claim 1, wherein: The space transformer is configured to focus the plurality of light beams at different positions in the external space, respectively.

12. The Fourier beam shaper according to claim 11, wherein: The external space is in the user's pupil.

13. The Fourier beam shaper according to claim 1, wherein: Each of the plurality of light beams is a pixel image of the frame image.

14. The Fourier beam shaper according to claim 1, wherein: The sizes of the plurality of light beams output from the space transformer are different from the sizes of the plurality of light beams incident on the input coupler.

15. The Fourier beam shaper according to claim 14, wherein: The sizes of the plurality of light beams output from the space transformer are larger than the sizes of the plurality of light beams incident on the input coupler.

16. The Fourier beam shaper according to claim 1, wherein: The first light beam and the second light beam are synchronized and incident on the first input coupler and the second input coupler, respectively, at the same time period.

17. The Fourier beam shaper according to claim 1, wherein: The first sub frame image and the second sub frame image are formed in different areas of the external space.

18. The Fourier beam shaper according to claim 17, wherein: The first sub-frame image and the second sub-frame image are different parts of a frame image.

19. A display device comprising: Fourier-beam shaper, including: A waveguide comprising: a first waveguide in which the first light beam travels and a second waveguide in which the second light beam travels; an input coupler configured to direct a plurality of light beams into the interior of the waveguide, and comprising: a first input coupler configured to direct a first light beam of the plurality of light beams into the interior of the waveguide in a time-sequential manner, and a second input coupler configured to direct a second light beam of the plurality of light beams into the interior of the waveguide in a time-sequential manner; and a space converter configured to output a plurality of light beams traveling in the waveguide through spatially different regions of the space converter, and comprising: a first space converter disposed on the first waveguide and configured to temporally output a first light beam through different regions of the first space converter to form a first subframe image in an external space, and a second space converter disposed on the second waveguide and configured to temporally output a second light beam through different regions of the second space converter to form a second subframe image in an external space; wherein each of the plurality of light beams is a partial image of a frame image, wherein the first waveguide and the second waveguide partially overlap each other in a direction perpendicular to the length direction of the first waveguide and the second waveguide, the first input coupler and the second input coupler do not overlap each other in a direction perpendicular to the length direction of the first waveguide and the second waveguide, and the first space transformer and the second space transformer do not overlap each other in a direction perpendicular to the length direction of the first waveguide and the second waveguide; and A light source is configured to output a plurality of light beams to the Fourier beam shaper.

20. The display device of claim 19, further comprising an exit pupil expander configured to expand the plurality of light beams output from the Fourier-beam shaper.

21. The display device according to claim 20, wherein: The exit pupil expander transmits light corresponding to the real environment.

22. The display device according to claim 19, further comprising a spatial light modulator configured to add image information to the plurality of light beams output from the Fourier-beam shaper or from the light source.

23. The display device according to claim 19, further comprising a direction adjusting member configured to adjust incident angles of the plurality of light beams incident on the Fourier-beam shaper.

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