Backlight device and display device including the same

Abstract

Disclosed are a backlight device and a display device including the backlight device. The backlight device includes: a light source emitting coherent light; an optical path difference generator located on the light source, the optical path difference generator including an incident surface and a plurality of light-emitting surfaces, the light-emitting surfaces being parallel to the incident surface and having different separation distances from the incident surface; a condenser located on the optical path difference generator; a diffuser located on the condenser; and a collimator located on the diffuser.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0116777 filed on September 23, 2019, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0003] Aspects of embodiments of the present disclosure relate to a backlight device and a holographic three-dimensional image display device including the backlight device. Background Art

[0004] Holographic technology for displaying three-dimensional (3D) stereoscopic images uses the principle of recording interference signals and reproducing the interference signals, wherein the interference signals are obtained by superposition of light reflected by an object (or object wave) and light having coherence (e.g., coherent light, reference light, or reference wave).

[0005] The interference pattern recorded on the film is called a hologram. The interference pattern is formed by combining an object wave, which is formed by scattering laser light with high coherence by colliding with an object, with a reference wave incident in a different direction. When the object wave and the reference wave combine, an interference pattern is formed by the interference between them, and such an interference pattern records the intensity and phase information of the light wave.

[0006] Restoring a stereoscopic image recorded as a hologram into a 3D image by irradiating a reference light onto an interference pattern is called holography. A holographic 3D image display device includes a spatial light modulator and a backlight unit, the spatial light modulator is configured to form an interference pattern according to interference pattern data, and the backlight unit is configured to irradiate a reference wave (or coherent light) onto the spatial light modulator.

[0007] The backlight unit includes a diffusion plate that uniformly provides coherent light to the entire spatial light modulator. However, when the coherent light is irradiated onto the diffusion plate, speckles (or speckle patterns) may be generated in a 3D image while the coherent light is partially interfered with by the random phase pattern of the diffusion plate.

[0008] The above information disclosed in this Background section is for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute prior art. Summary of the invention

[0009] One or more embodiments of the present disclosure relate to a backlight device and a holographic 3D image display device capable of reducing speckles of a 3D image.

[0010] According to an exemplary embodiment of the present disclosure, a backlight device includes: a light source configured to emit coherent light; an optical path difference generator located on the light source, the optical path difference generator including an incident surface and a plurality of light emitting surfaces, the light emitting surfaces being parallel to the incident surface and having different separation distances from the incident surface; a condenser located on the optical path difference generator; a diffuser located on the condenser; and a collimator located on the diffuser.

[0011] In an exemplary embodiment, the optical path difference generator may include a first layer and a second layer located on the first layer, the second layer partially overlapping the first layer. A portion of the first layer may be exposed by the second layer and may include a first light emitting surface among a plurality of light emitting surfaces, and at least a portion of the second layer may overlap with the first layer and may include a second light emitting surface among a plurality of light emitting surfaces.

[0012] In an exemplary embodiment, the thickness of the second layer may be greater than the temporal coherence length of the coherent light.

[0013] In an exemplary embodiment, the temporal coherence length may be defined as the distance that the coherent light moves within the delay time, and the delay time may be defined as the amount of time until the coherence between the coherent light and the delayed light is reduced to a value of 0, the coherence being obtained by delaying the coherent light by the delay time.

[0014] In an exemplary embodiment, the thickness of the second layer may be equal to the thickness of the first layer.

[0015] In an exemplary embodiment, in a plan view, an area of ​​the second layer may be smaller than an area of ​​the first layer.

[0016] In an exemplary embodiment, an area of ​​the first light emitting surface may be equal to an area of ​​the second light emitting surface.

[0017] According to an exemplary embodiment of the present disclosure, a display device includes a backlight device and a light modulator located on the backlight device. The backlight device includes: a light source configured to emit coherent light; and an optical path difference generator located on the light source, the optical path difference generator including an incident surface and a plurality of light emitting surfaces, the light emitting surfaces being parallel to the incident surface and having different separation distances from the incident surface.

[0018] In an exemplary embodiment, the light source may include: a display panel including a plurality of pixels, each of the pixels including a light emitting element; and a first collimator located on the display panel, the first collimator including a plurality of collimating lenses respectively corresponding to the pixels. The optical path difference generator may include a pattern including each of the light emitting surfaces, the pattern being repeatedly arranged, and the pattern of the optical path difference generator may correspond to at least one pixel.

[0019] In an exemplary embodiment, the light modulator may include a liquid crystal display panel including a plurality of liquid crystal elements respectively corresponding to pixels.

[0020] In an exemplary embodiment, the pattern may include: a first sub-pattern located at a first layer; and a second sub-pattern located at a second layer different from the first layer, the area of ​​the second sub-pattern being smaller than the area of ​​the first sub-pattern. A portion of the first sub-pattern may be exposed by the second sub-pattern and may include a first light emitting surface among a plurality of light emitting surfaces, and at least a portion of the second sub-pattern may overlap with the first sub-pattern and may include a second light emitting surface among the plurality of light emitting surfaces.

[0021] In exemplary embodiments, each of the first sub-pattern and the second sub-pattern may have a circular plan shape or a quadrangular plan shape.

[0022] In an exemplary embodiment, the pattern may include a first layer having a first opening and a second layer located on the first layer, the second layer having a second opening overlapping the first opening. A portion of the first layer may be exposed by the second opening and may include a first light emitting surface among the plurality of light emitting surfaces, and at least a portion of the second layer may not overlap with the first opening and may include a second light emitting surface among the plurality of light emitting surfaces.

[0023] In an exemplary embodiment, the optical path difference generator may include a first layer and a second layer located on the first layer, the first layer may have a first opening having a width, the first opening extending in a first direction and being repeatedly arranged along a second direction intersecting the first direction, and the second layer may include a second opening having a width, the second opening extending in the second direction and being repeatedly arranged along the first direction.

[0024] In an exemplary embodiment, a thickness of the first layer may be greater than a temporal coherence length of the coherent light, and a thickness of the second layer may be greater than a thickness of the first layer.

[0025] In an exemplary embodiment, the pattern of the optical path difference generator may correspond to at least two of the pixels, the optical path difference generator may include a first layer and a second layer located on the first layer, each of the first layer and the second layer may have an opening extending in a first direction, the openings are repeatedly arranged along a second direction intersecting the first direction, and the openings of the first layer may partially overlap with the openings of the second layer.

[0026] In an exemplary embodiment, the backlight device may further include: a condenser located on the optical path difference generator; a diffuser located on the condenser; and a second collimator located on the diffuser. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and other aspects and features of the present disclosure will become more apparent to those skilled in the art from the following detailed description of exemplary embodiments with reference to the accompanying drawings.

[0028] Figure 1 is a diagram illustrating a display device according to an embodiment of the present disclosure.

[0029] Figure 2 It is shown that the Figure 1 A diagram of an example of a speckle reducer in a display device shown in .

[0030] Figure 3 It is shown that the Figure 2 A diagram of an example of an optical path difference generator in a speckle reducer is shown in FIG.

[0031] Figures 4 to 5 It is shown Figure 1 FIG. 4 is a diagram of an example of a display device shown in FIG.

[0032] FIG. 6A to FIG. 6B It is shown that the Figure 5 Graphs of various examples of speckle reducers in display devices are shown in .

[0033] FIG. 7A to FIG. 7B It is shown that the Figure 5 Schematic diagrams of various other examples of speckle reducers in display devices are shown in .

[0034] Figure 8 It is shown that the Figure 5 FIG. 4 is a diagram of another example of a speckle reducer in a display device shown in FIG.

[0035] FIG. 9A to FIG. 9B It is shown that the Figure 5 FIG. 4 is a diagram of another example of a speckle reducer in a display device shown in FIG.

[0036] Fig.10 It is shown that the Figure 5 FIG. 4 is a diagram of another example of a speckle reducer in a display device shown in FIG. DETAILED DESCRIPTION

[0037] Hereinafter, exemplary embodiments will be described in more detail with reference to the accompanying drawings, in which the same reference numerals always represent the same elements. However, the present disclosure may be implemented in various different forms and should not be construed as being limited to the embodiments shown herein. On the contrary, these embodiments are provided as examples so that the present disclosure will be thorough and complete, and the aspects and features of the present disclosure will be fully conveyed to those skilled in the art. Therefore, processes, elements and techniques that are unnecessary for those of ordinary skill in the art to fully understand the aspects and features of the present disclosure may not be described. Unless otherwise stated, in all drawings and written descriptions, the same reference numerals represent the same elements, and therefore, descriptions thereof may not be repeated.

[0038] In the accompanying drawings, for the sake of clarity, the relative sizes of elements, layers and regions can be exaggerated and / or simplified. For ease of explanation, spatial relative terms such as "below", "below", "lower", "below", "above", "upper" can be used in this article to describe the relationship between an element or feature and another element or feature as shown in the drawings. It should be understood that, in addition to the orientations depicted in the drawings, spatial relative terms are intended to include different orientations of the device in use or in operation. For example, if the device in the drawings is turned over, the elements or features described as "below" or "below" or "below" other elements or features will be oriented to be "above" the other elements or features. Therefore, the exemplary terms "below" and "below" can include both above and below orientations. The device can be oriented in other ways (for example, rotated 90 degrees or in other orientations), and the spatial relative descriptors used in this article should be interpreted accordingly.

[0039] It should be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Therefore, without departing from the spirit and scope of the present disclosure, the first element, component, region, layer or section described below may be referred to as a second element, component, region, layer or section.

[0040] It should be understood that when an element or layer is referred to as being "on," "connected to," or "coupled to" another element or layer, it can be directly on, directly connected to, or directly coupled to the other element or layer, or there can be one or more intervening elements or layers. In addition, it should be understood that when an element or layer is referred to as being "between" two elements or layers, it can be the only element or layer between the two elements or layers, or there can be one or more intervening elements or layers.

[0041] The terms used herein are for the purpose of describing a particular embodiment, and are not intended to limit the present invention. As used herein, the singular forms "one" and "an" are intended to also include plural forms, unless the context clearly indicates otherwise. It should also be understood that when the terms "comprises", "comprising", "includes" and "including", "has", "have" and "having" are used in this specification, the existence of the features, integers, steps, operations, elements and / or components set forth is specified, but the existence or addition of one or more other features, integers, steps, operations, elements, components and / or their groups is not excluded. As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items. When a statement such as "at least one of" is after the list of elements, the entire list of modified elements is modified without modifying each element in the list.

[0042] As used herein, the terms "substantially," "about," and similar terms are used as approximate terms rather than as terms of degree, and are intended to account for the inherent deviations in measurements or calculations that one of ordinary skill in the art would recognize. In addition, when describing embodiments of the present disclosure, the use of "may" refers to "one or more embodiments of the present disclosure." As used herein, the terms "use," "using," and "used" may be considered synonymous with the terms "utilize," "utilizing," and "utilized," respectively. In addition, the term "exemplary" is intended to mean an example or illustration.

[0043] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present disclosure belongs. It should also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and / or this specification, and should not be interpreted in an idealized or overly formal sense, unless explicitly defined as such herein.

[0044] Figure 1 is a diagram illustrating a display device according to an embodiment of the present disclosure.

[0045] refer to Figure 1 The display device 10 (eg, a three-dimensional image display device or a holographic three-dimensional image display device) may include a backlight unit (eg, a backlight device) 100 and a light modulator (eg, a spatial light modulator) 200.

[0046] The backlight unit 100 may generate coherent light, and may emit coherent light in a first direction DR1 (e.g., an upward direction or a forward direction). Coherent light may refer to two or more beams of light that can cause interference because the phase and frequency (or wavelength) are constant in time or space. For example, the coherent light may be a laser. Coherence is divided into spatial coherence and temporal coherence. Spatial coherence may be determined by the degree of wavefront alignment of the advancing light, and temporal coherence may be determined by the time during which the correlation between time and intensity is maintained or substantially maintained when the intensity of the light is measured at a point according to the time.

[0047] The backlight unit 100 may include a light source (eg, a coherent light source) 110 and a speckle reducer 120 .

[0048] The light source 110 may emit the first coherent light CL1 in the first direction DR1. For example, the light source 110 may be a laser light source. However, the present disclosure is not limited thereto, and the light source 110 may be implemented as a display panel including a light emitting element for emitting monochromatic light. This will be described below with reference to Figure 4 Describe in more detail.

[0049] The speckle reducer 120 (or optical path difference generator) may include a plurality of optical paths arranged in a first direction DR1 relative to the light source 110. The plurality of optical paths may have different lengths from each other. The first coherent light CL1 irradiated from the light source 110 passes through the optical paths, and the second coherent light CL2 may be emitted by the speckle reducer 120. The second coherent light CL2 may include a plurality of beams (e.g., a plurality of light waves) having different phase distributions from each other according to the optical paths. Therefore, the spatial coherence of the second coherent light CL2 may be reduced. Figure 2 A more detailed configuration of the speckle reducer 120 is described.

[0050] The light modulator 200 may be disposed in the first direction DR1 relative to the backlight unit 100, and may express phase information of an object wave of an object by modulating coherent light (e.g., second coherent light CL2) provided from the backlight unit 100. For example, the light modulator 200 may express a three-dimensional (3D) image by modulating the coherent light.

[0051] In an implementation, the light modulator 200 may be implemented as a liquid crystal display panel, and may change the phase and polarization state of coherent light by using the birefringence property of liquid crystal.

[0052] As described above, since the coherent light (e.g., second coherent light CL2) provided from the speckle reducer 120 to the light modulator 200 includes a plurality of light beams having different phases from each other, even when the respective light beams generate speckles, the speckles may be different from each other. When different speckles overlap each other, the speckle brightness (e.g., the brightness of the speckle relative to the average brightness) may be reduced, and thus, the speckle (e.g., any speckle) may not be observed (e.g., may not be visible) in a three-dimensional image.

[0053] Figure 2 It is shown that the Figure 1 A diagram of an example of a speckle reducer in a display device shown in .

[0054] refer to Figure 1 and Figure 2 The speckle reducer 120 may include an optical path difference generator (eg, an optical structure) 121 , a condenser (eg, a condenser lens) 122 , a diffuser 123 , and a collimator (eg, a collimating lens) 124 .

[0055] The optical path difference generator 121 may be disposed in the first direction DR1 relative to the light source 110. The optical path difference generator 121 may have an incident surface (e.g., one incident surface) and a plurality of light emitting surfaces. The light emitting surfaces may be parallel to the incident surface, may have different separation distances from the incident surface, and may provide different optical paths in relation to the incident surface relative to the first coherent light CL1.

[0056] Reference Figure 3 The optical path difference generator 121 is described in more detail. After the optical path difference generator 121 is described in more detail, the condenser 122, the diffuser 123, and the collimator 124 will be described in more detail.

[0057] Figure 3 It is shown that the Figure 2 A diagram of an example of an optical path difference generator in a speckle reducer is shown in FIG.

[0058] refer to Figure 2 and Figure 3 , the optical path difference generator 121 (or the speckle reducer 120) may include a plurality of layers GP1 to GP6. Each of the plurality of layers GP1 to GP6 may be implemented as a plate including (e.g., made of) a material through which light can be transmitted, such as, for example, a glass plate. The layers GP1 to GP6 may be arranged parallel to each other. In other words, the optical path difference generator 121 may be configured with a plurality of (e.g., a stack of) glass plates (e.g., tiers) arranged in a stair shape.

[0059] The first layer GP1 of the layers GP1 to GP6 may be disposed closest to (eg, most adjacent to) the light source 110 (eg, see Figure 1), and may include (eg, may form or may constitute) an incident surface S_INC of the optical path difference generator 121.

[0060] The second layer GP2 may be disposed on the first layer GP1, and may partially overlap with the first layer GP1 (e.g., in the first direction DR1). The area of ​​the second layer GP2 may be smaller than the area of ​​the first layer GP1. For example, the width W of the second layer GP2 in the third direction DR3 may be equal to or substantially equal to the width W of the first layer GP1 in the third direction DR3, and the length (e.g., the second length) L2 of the second layer GP2 in the second direction DR2 may be shorter than the length (e.g., the first length) L1 of the first layer GP1 in the second direction DR2. However, the present disclosure is not limited thereto, and the area of ​​the second layer GP2 may be equal to or substantially equal to the area of ​​the first layer GP1. This will be described below with reference to Fig.9A Describe in more detail.

[0061] although Figure 3 An exemplary embodiment is shown in which the three side surfaces of the second layer GP2 are arranged on the same plane as the three side surfaces of the first layer GP1, or the three side surfaces of the second layer GP2 are arranged according to the three side surfaces of the first layer GP1 (for example, corresponding to the three side surfaces of the first layer GP1 or aligned with the three side surfaces of the first layer GP1), but the present disclosure is not limited thereto, and the arrangement of the first layer GP1 and the second layer GP2 is not limited to Figure 3 The embodiment shown in .

[0062] The portion of the first layer GP1 exposed by the second layer GP2 (e.g., not overlapping with the second layer GP2) may include (e.g., may form or may constitute) a first light emitting surface S_EX1 among the light emitting surfaces S_EX1 to S_EX6. At least a portion of the second layer GP2 overlapping with the first layer GP1 (e.g., in the first direction DR1) may include (e.g., may form or may constitute) a second light emitting surface S_EX2 among the light emitting surfaces S_EX1 to S_EX6. A side surface of the second layer GP2 (e.g., a side surface in a second direction DR2 intersecting or perpendicular to the first direction DR1) may be parallel or substantially parallel to the first coherent light CL1 advancing in the first direction DR1 (e.g., see Figure 2 ).

[0063] Similarly, the third layer GP3 may be disposed on the second layer GP2 and may partially overlap with the second layer GP2 (e.g., in the first direction DR1). The area of ​​the third layer GP3 may be smaller than the area of ​​the second layer GP2. The portion of the second layer GP2 that overlaps with the first layer GP1 (e.g., in the first direction DR1) and is exposed by the third layer GP3 (e.g., does not overlap with the third layer GP3) may include (e.g., may form or may constitute) the second light emitting surface S_EX2. In other words, the (n+1)th layer GPn+1 (where n is a positive integer, as an example, Figure 3 Only the first layer GP1 to the sixth layer GP6 are shown) may be disposed on the nth layer GPn and may partially overlap with the nth layer GPn. The area of ​​the (n+1)th layer GPn+1 may be smaller than the area of ​​the nth layer GPn. The portion of the nth layer GPn overlapping with the (n-1)th layer GPn-1 and exposed by the (n+1)th layer GPn+1 may include (e.g., may form or may constitute) the nth light emitting surface S_EXn (as an example, Figure 3 Only the first to sixth light emitting surfaces S_EX1 to S_EX6 are shown.

[0064] Therefore, if Figure 3 As shown in, the fourth layer GP4 can be arranged on the third layer GP3, and can partially overlap with the third layer GP3. The fourth layer GP4 may include (e.g., can be formed or can be composed of) a fourth light emitting surface S_EX4. The fifth layer GP5 can be arranged on the fourth layer GP4, and can partially overlap with the fourth layer GP4. The fifth layer GP5 may include (e.g., can be formed or can be composed of) a fifth light emitting surface S_EX5. In addition, the sixth layer GP6 can be arranged on the fifth layer GP5, and can partially overlap with the fifth layer GP5. The sixth layer GP6 may include (e.g., can be formed or can be composed of) a sixth light emitting surface S_EX6.

[0065] The first wave CL_W1 emitted by the first light emitting surface S_EX1 may be relative to the incident first coherent light CL1 (eg, see Figure 2) has a path difference corresponding to the first thickness T1 of the first layer GP1 (for example, in the first direction DR1). Similarly, the second wave CL_W2 emitted through the second light emitting surface S_EX2 may have a path difference corresponding to the sum of the second thickness T2 of the second layer GP2 (for example, in the first direction DR1) and the first thickness T1 of the first layer GP1. The third wave CL_W3 emitted through the third light emitting surface S_EX3 may have a path difference corresponding to the sum of the thicknesses of the first layer GP1, the second layer GP2, and the third layer GP3 (for example, T1+T2+T3), the fourth wave CL_W4 emitted through the fourth light emitting surface S_EX4 may have a path difference corresponding to the sum of the thicknesses of the first layer GP1 to the fourth layer GP4 (for example, T1+T2+T3+T4), and so on. In other words, the nth wave CL_Wn (as an example, Figure 3 Only the first to sixth waves CL_W1 to CL_W6 are shown to have a path difference corresponding to the sum of the thicknesses of the first to n-th layers GP1 to GPn (eg, T1+T2+ . . . +Tn).

[0066] In some embodiments, each of the thicknesses T1 to T6 of the first to sixth layers GP1 to GP6 may be greater than the coherent light (eg, Figure 2 . The temporal coherence length of the first coherent light CL1 shown in . The temporal coherence length can be defined as the distance that the coherent light moves during the delay time, and the delay time can be defined as a suitable or desired amount of time until the coherence between the coherent light (e.g., the first wave CL_W1) and the delayed light (e.g., the second wave CL_W2) is reduced to a value of 0, the coherence being obtained by delaying the coherent light by the delay time. The temporal coherence length can be proportional to the speed of the light (e.g., the coherent light) and can be inversely proportional to the refractive index of the medium (e.g., the square root of the refractive index). For example, the temporal coherence length can be a few μm to several hundred μm. In some embodiments, the spatial coherence of the first wave CL_W1 to the sixth wave CL_W6 can be reduced.

[0067] In an embodiment, the thicknesses T1 to T6 of the first to sixth layers GP1 to GP6 may be the same or substantially the same as each other. For example, each of the thicknesses T1 to T6 of the first to sixth layers GP1 to GP6 may be equal to or substantially equal to the temporal coherence length. The total thickness of the optical path difference generator 121 may be reduced or minimized.

[0068] In an embodiment, the light emitting surfaces S_EX1 to S_EX6 may have the same or substantially the same area as each other.Therefore, the first to sixth waves CL_W1 to CL_W6 having different path differences (or different phases) may be generated at the same or substantially the same (or similar) rates.

[0069] although Figure 3 An exemplary embodiment in which six layers GP1 to GP6 are included in the optical path difference generator 121 is shown, but the present disclosure is not limited thereto, and the optical path difference generator 121 may have any suitable or desired number of layers (e.g., less than six layers or more than six layers). For example, the speckle brightness in the three-dimensional image may be reduced according to the square root of the number of layers GP1 to GP6, and considering the relationship between the degree of reduction (e.g., the amount of reduction) of the speckle brightness and the number of layers, the optical path difference generator 121 may include more or fewer layers (e.g., 7 or more layers or 5 or less layers).

[0070] Return to reference Figure 2 The condenser 122 can be set in the first direction DR1 relative to the optical path difference generator 121, and can converge (for example, can concentrate) multiple beams of light (for example, the first wave CL_W1 to the sixth wave CL_W6) transmitted through the optical path difference generator 121 (for example, can converge the light CL_M1 whose spatial coherence is reduced) to generate converged light CL_M2.

[0071] The diffuser 123 may be disposed in the first direction DR1 relative to the condenser 122 and may diffuse the condensed light CL_M2 to generate diffused light CL_M3. Coherent light may be provided (eg, uniformly provided) to the entire (eg, all) light modulator 200 through the diffuser 123. The diffuser 123 may be disposed at a focal length of the condenser 122.

[0072] The collimator 124 may be disposed in the first direction DR1 with respect to the diffuser 123 and may convert the diffused light CL_M3 into parallel light (eg, CL2). The collimator 124 may be disposed to be spaced apart from the diffuser 123 by the above-mentioned focal length.

[0073] Different phases may be provided to the light CL_M1 whose spatial coherence is reduced by the diffuser 123 , and the light converted by the collimator 124 may be considered as overlapping lights having different phases from each other.

[0074] As reference Figure 1 As described, parallel light may be provided as the second coherent light CL2 to the optical modulator 200. When different speckle patterns generated by parallel light (eg, light having different phases from each other) overlap each other, the speckle brightness may be reduced.

[0075] As reference Figure 2 and Figure 3As described, the optical path difference generator 121 (or the speckle reducer 120) can provide different optical paths, can provide different phases to the coherent light transmitted through the optical path difference generator 121, and can generate different speckles, and the different speckles can overlap each other due to the different phases. Therefore, the speckle brightness can be reduced, and the speckle (e.g., any speckle) may not be observed (e.g., may not be easily observed or may not be easily noticed).

[0076] although Figure 2 An exemplary embodiment is shown in which the speckle reducer 120 includes a condenser 122, a diffuser 123, and a collimator 124 in addition to the optical path difference generator 121, but the present disclosure is not limited thereto. For example, in another embodiment, the speckle reducer 120 may include the optical path difference generator 121, but the condenser 122, the diffuser 123, and / or the collimator 124 may be omitted (e.g., may not be included).

[0077] Figure 4 and Figure 5 It is shown Figure 1 FIG. 1 is a diagram of an example of a display device shown in FIG. Figure 4 , a plan view of a display device 10_1 including a light source 410 and a light modulator 430 is shown. As used herein, a plan view refers to a view observed from a plane parallel to or substantially parallel to (or perpendicular to) the top surface of a relevant component, layer or element (e.g., display device 10_1). Figure 5 , a side view (eg, a cross-sectional view) of a portion of the display device 10_1 including the light source 410 is shown.

[0078] refer to Figure 1 and Figure 4 , the display device 10_1 may include a light source 410 , a speckle reducer 420 (eg, or an optical path difference generator), and a light modulator 430 .

[0079] The light source 410 may be implemented as a display device. For example, the light source 410 may be implemented as an organic light emitting display device. However, the present disclosure is not limited thereto, and the light source 410 may be implemented as an inorganic light emitting display device.

[0080] The light source 410 may include a first display panel 411 , a first scan driver 412 , a first data driver 413 , and a first controller 414 .

[0081] The first display panel 411 may include first scan lines BSL1 to BSLn (e.g., first backlight scan lines BSL1 to nth backlight scan lines BSLn) (where n is a positive integer), first data lines BDL1 to BDLm (e.g., first backlight data lines BDL1 to mth backlight data lines BDLm) (where m is a positive integer), and first pixels BP. The first scan lines BSL1 to BSLn may be arranged along the second direction DR2 with respect to each other, and each of the first scan lines BSL1 to BSLn may extend in a third direction DR3. The first data lines BDL1 to BDLm may be arranged along the third direction DR3 with respect to each other, and each of the first data lines BDL1 to BDLm may extend in the second direction DR2.

[0082] The first pixels BP may be disposed at (e.g., in or above) an area (e.g., a cross area) defined by the first scan lines BSL1 to BSLn and the first data lines BDL1 to BDLm, and each of the first pixels BP may be connected to at least one of the first scan lines BSL1 to BSLn and one of the first data lines BDL1 to BDLm. Each of the first pixels BP may include a light emitting element (e.g., a light emitting diode) and a transistor (e.g., at least one transistor) that supplies a driving current corresponding to a first data signal to the light emitting element. The light emitting element emits light having a desired brightness corresponding to the driving current, and may be an organic light emitting element or an inorganic light emitting element.

[0083] The first scan driver 412 may generate a first scan signal according to (e.g., based on) a first scan control signal SCS1, and may provide (e.g., may sequentially provide) the first scan signal to the first scan lines BSL1 to BSLn. The first scan control signal SCS1 may include a start signal, one or more clock signals, etc., and may be provided from the first controller 414. For example, the first scan driver 412 may include a shift register (e.g., a stage) that sequentially generates and outputs a first scan signal in the form of a pulse corresponding to the start signal in the form of a pulse by using a clock signal.

[0084] The first data driver 413 may generate a first data signal according to (e.g., based on) the second image data BDATA2 and the first data control signal DCS1 provided from the first controller 414, and may provide the first data signal to the first display panel 411. The first data control signal DCS1 may be a signal for controlling the operation of the first data driver 413, and may include a load signal (e.g., a data enable signal) for instructing output of a valid data signal, and the like.

[0085] The first controller 414 may receive the first image data BDATA1 and the control signal CS from the outside (e.g., from a graphics processor), may generate the first scan control signal SCS1 and the first data control signal DCS1 according to (e.g., based on) the control signal CS, and may convert the first image data BDATA1 into the second image data BDATA2 corresponding to the pixel arrangement of the first display panel 411. The first scan driver 412, the first data driver 413, and the first controller 414 may be implemented as integrated circuits, and at least two of the first scan driver 412, the first data driver 413, and the first controller 414 may be included in one integrated circuit (e.g., may be integrally formed as one integrated circuit).

[0086] like Figure 5 As shown in , the first display panel 411 may further include a first collimator (eg, a collimating lens array) LA that converts diffuse light emitted from the first display panel 411 (eg, from the first pixels BP) into parallel light.

[0087] The speckle reducer 420 may be arranged relative to the first display panel 411 (eg, see Figure 4 ) is disposed in the first direction DR1 and may cover a light emitting area of ​​the first display panel 411.

[0088] The light modulator 430 may be implemented as a liquid crystal display device.

[0089] The light modulator 430 may include a second display panel (eg, a liquid crystal display panel) 431 , a second scan driver 432 , a second data driver 433 , and a second controller 434 .

[0090] Similar to the first display panel 411, the second display panel 431 may include second scan lines SSL1 to SSLn (e.g., first to n-th light modulation scan lines SSL1 to SSLn), second data lines SDL1 to SDLm (e.g., first to m-th light modulation data lines SDL1 to SDLm), and second pixels SP. The second scan lines SSL1 to SSLn may be arranged along the second direction DR2, and each of the second scan lines SSL1 to SSLn may extend in a third direction DR3. The second data lines SDL1 to SDLm may be arranged along the third direction DR3, and each of the second data lines SDL1 to SDLm may extend in the second direction DR2.

[0091] The second pixels SP may be arranged to correspond to the first pixels BP (e.g., one-to-one correspondence), and each of the second pixels SP may be connected to at least one of the second scan lines SSL1 to SSLn and one of the second data lines SDL1 to SDLm. Each of the second pixels SP may include a liquid crystal element and a transistor (e.g., at least one transistor) that provides a second data signal to the liquid crystal element. The liquid crystal element may polarize incident light corresponding to the second data signal. One pixel of the display device 10_1 may include at least one second pixel SP and at least one first pixel BP.

[0092] Similar to the first scan driver 412, the second scan driver 432 may generate a second scan signal according to (e.g., based on) the second scan control signal SCS2, and may provide (e.g., may sequentially provide) the second scan signal to the second scan lines SSL1 to SSLn. The second scan driver 432 may operate in synchronization with the first scan driver 412. For example, when the first scan driver 412 selects a first pixel BP, the second scan driver 432 may select a second pixel SP corresponding to the selected first pixel BP.

[0093] Similar to the first data driver 413 , the second data driver 433 may generate a second data signal according to (eg, based on) the second interference pattern data SDATA2 and the second data control signal DCS2 provided from the second controller 434 .

[0094] Similar to the first controller 414, the second controller 434 can receive the first interference pattern data SDATA1 and the control signal CS, can generate a second scan control signal SCS2 and a second data control signal DCS2 according to (e.g., based on) the control signal CS, and can convert the first interference pattern data SDATA1 into second interference pattern data SDATA2 that can be used by the second data driver 433.

[0095] The second scan driver 432, the second data driver 433, and the second controller 434 may be implemented as an integrated circuit, and at least two of the second scan driver 432, the second data driver 433, and the second controller 434 may be included in one integrated circuit (e.g., may be integrally formed as one integrated circuit). In an exemplary embodiment, the second controller 434 may be integrally configured with the first controller 414 (e.g., may be integrally formed).

[0096] refer to Figure 5, the first display panel 411 may include a first substrate SUB1 and a plurality of light emitting elements LD1 to LD4. The light emitting elements LD1 to LD4 may be disposed on the first substrate SUB1. Each of the light emitting elements LD1 to LD4 may be included in a first pixel BP (e.g., may be formed in the first pixel BP or may constitute the first pixel BP). In other words, one light emitting element LD may form (e.g., may constitute) one pixel. The light emitting elements LD1 to LD4 may be distinguished from each other by reference lines LREF1 to LREF5. Partition walls may be disposed between the light emitting elements LD1 to LD4 to prevent or substantially prevent light diffused from adjacent light emitting elements from being introduced into other light emitting elements.

[0097] In some embodiments, at least some of the light emitting elements LD1 to LD4 may emit light having different colors (e.g., different monochromatic colors) from each other. For example, the first light emitting element LD1 (e.g., and the fourth light emitting element LD4) may emit light having a first color (e.g., red), the second light emitting element LD2 may emit light having a second color (e.g., green), and the third light emitting element LD3 may emit light having a third color (e.g., blue), but the present disclosure is not limited thereto.

[0098] The first collimator (eg, collimating lens array) LA may include a lens array corresponding to each of the light emitting elements LD1 to LD4 (eg, Figure 4 The collimating lens LE corresponds to the first pixel BP shown in FIG. The collimating lens LE may convert diffuse light emitted from each of the light emitting elements LD1 to LD4 into parallel light.

[0099] In some embodiments, a polarization device for polarizing the parallel light may be disposed on the first collimator LA.

[0100] The speckle reducer 420 (e.g., an optical path difference generator) may include a pattern (e.g., an optical structure or a unit optical structure) EU that is repeatedly arranged and provides a plurality of light paths. The pattern EU may be arranged corresponding to each of the light emitting elements LD1 to LD4 (or may be arranged corresponding to each first pixel BP). However, the present disclosure is not limited thereto, and the pattern EU may be arranged to correspond to a plurality of light emitting elements or a plurality of pixels.

[0101] The second display panel 431 of the light modulator 430 may include a second substrate SUB2 and a plurality of liquid crystal elements LC1 to LC4. The liquid crystal elements LC1 to LC4 may be disposed on the second substrate SUB2. As described above, the liquid crystal elements LC1 to LC4 may be disposed to correspond to the corresponding light emitting elements LD1 to LD4 and may be included in the second pixel SP (e.g., may be formed in the second pixel SP or may constitute the second pixel SP).

[0102] As mentioned above Figure 4 and Figure 5 As described, the light source 410 may be implemented as a light emitting display device (eg, an organic light emitting display device), and the light modulator 430 may be implemented as a liquid crystal display device.

[0103] Fig. 6A and Figure 6B It is shown that the Figure 5 , which are diagrams of various examples of speckle reducers in display devices. Fig. 6A and Figure 6B Each speckle reducer is shown implemented as a reference Figure 3 The optical path difference generator 121 described above is an embodiment of the present disclosure, but the present disclosure is not limited thereto. For example, the speckle reducer may also be as described in reference Figure 2 As described, a condenser 122, a diffuser 123 and / or a collimator 124 are included.

[0104] refer to Figure 5 and Fig. 6A , the speckle reducer 420 (eg, an optical path difference generator) may include a first layer GP1, a second layer, and a third layer. Fig. 6A and Figure 6B 2 shows an embodiment in which the speckle reducer 420 includes three layers. However, the present disclosure is not limited thereto, and the speckle reducer 420 may include, for example, four or more layers.

[0105] The second layer may be disposed on the first layer GP1 and may include a first sub-pattern GP_P1. The first sub-pattern GP_P1 may be provided with respect to the pattern EU distinguished by the reference lines LREF1 to LREF4 (eg, see Figure 5 ) are spaced apart from each other, and a portion of the first layer GP1 may be exposed by the first sub-pattern GP_P1 at (eg, in or above) the pattern EU. The portion of the first layer GP1 exposed by the first sub-pattern GP_P1 may include (eg, may form or may constitute) the above reference Figure 3 Described is the first light emitting surface S_EX1.

[0106] For example, Fig. 6A As shown in the plan view of the first pattern EU_1 in FIG. 1 , the first sub-pattern GP_P1 may have a circular planar shape (eg, a circular shape when viewed in a plan view). However, the present disclosure is not limited thereto. For example, Fig. 6A As shown in the plan view of the second pattern EU_2 in FIG. 1 , the first sub-pattern GP_P1 may have a quadrilateral planar shape (eg, a quadrilateral shape when viewed in a plan view). However, Fig. 6AThe plane shape shown in FIG. 1 is merely illustrative, and the first sub-pattern GP_P1 may have any suitable plane shape, such as, for example, a polygonal shape (eg, a pentagonal shape, a hexagonal shape, etc.), an elliptical shape, or other suitable plane shapes.

[0107] Similarly, the third layer may be disposed on the second layer and may include a second sub-pattern GP_P2. The second sub-pattern GP_P2 may be relative to the pattern EU (eg, see Figure 5 ) are spaced apart from each other. The area of ​​the second sub-pattern GP_P2 may be smaller than the area of ​​the first sub-pattern GP_P1, and may be arranged to overlap with the first sub-pattern GP_P1. A portion of the first sub-pattern GP_P1 may be exposed by the second sub-pattern GP_P2 at (e.g., in or above) the pattern EU. The portion of the first sub-pattern GP_P1 exposed by the second sub-pattern GP_P2 may include (e.g., may form or may constitute) the above reference Figure 3 Described second light emitting surface S_EX2.

[0108] The second sub-pattern GP_P2 may have a shape corresponding to the first sub-pattern GP_P1. For example, the second sub-pattern GP_P2 may have any suitable planar shape, such as a polygonal shape (e.g., a quadrilateral shape, a pentagonal shape, a hexagonal shape, etc.), a circular shape, an elliptical shape, or other suitable planar shapes.

[0109] refer to Figure 6B , the speckle reducer 420_1 (eg, an optical path difference generator) may include a first layer GP1, a second layer GP2, and a third layer GP3.

[0110] The second layer GP2 may be disposed on the first layer GP1 and may include a first opening (eg, a first opening pattern or a first hole) OP1. The first opening OP1 may be formed with respect to a pattern EU (eg, see FIG. 1 ) distinguished by reference lines LREF1 to LREF3. Figure 5 ) are spaced apart from each other, and a portion of the first layer GP1 may be exposed by the first opening OP1 at (eg, in or above) the pattern EU.

[0111] For example, Figure 6B As shown in the plan view of the third pattern EU_3 in FIG. 1 , the first opening OP1 may have a circular planar shape (eg, a circular shape when viewed in a plan view). However, the present disclosure is not limited thereto. Figure 6B As shown in the plan view of the fourth pattern EU_4 in FIG. 1 , the first opening OP1 may have a quadrilateral planar shape (eg, a quadrilateral shape when viewed in a plan view). However, Figure 6BThe planar shape shown in FIG. 1 is merely illustrative, and the first opening OP1 may have any suitable planar shape, such as, for example, a polygonal shape (eg, a pentagonal shape, a hexagonal shape, etc.), an elliptical shape, or other suitable planar shapes.

[0112] Similarly, the third layer GP3 may be disposed on the second layer GP2 and may include a second opening OP2. The second opening OP2 may be opposite to the pattern EU (eg, see Figure 5 ) are spaced apart from each other. The area of ​​the second opening OP2 may be greater than the area of ​​the first opening OP1, and may be arranged to overlap with the first opening OP1. A portion of the first layer GP1 and a portion of the second layer GP2 may be exposed by the second opening OP2 at the pattern EU (e.g., in the middle or on). The second opening OP2 may have a shape corresponding to the first opening OP1. For example, the second opening OP2 may have any suitable planar shape, for example, such as a polygonal shape (e.g., a quadrilateral shape, a pentagonal shape, a hexagonal shape, etc.), a circular shape, an elliptical shape, or other suitable planar shapes.

[0113] As mentioned above Fig. 6A and Figure 6B As described, the speckle reducer (eg, optical path difference generator) may include a pattern (eg, optical structure or unit optical structure) EU corresponding to a pixel (eg, first pixel BP).

[0114] Fig. 7A and Figure 7B It is shown that the Figure 5 Schematic diagrams of various other examples of speckle reducers in display devices are shown in . Figure 5 A plan view of a portion of a speckle reducer 420 is shown as an example in Fig. 7A and Figure 7B Shown in.

[0115] refer to Figure 4 , Figure 5 and Fig. 7A , the speckle reducer 420_2 (eg, an optical path difference generator) may include a first layer GP1 and a second layer GP2.

[0116] The first layer GP1 may include a first opening OP1. The first opening OP1 may have a width (eg, a certain width or a predetermined width), may extend in the second direction DR2, and may be repeatedly arranged along the third direction DR3.

[0117] The second layer GP2 may be disposed on the first layer GP1 and may include a second opening OP2. The second opening OP2 may have a width (e.g., a specific width or a predetermined width), may extend in the third direction DR3, and may be repeatedly arranged along the second direction DR2. The second layer GP2 may be the same or substantially the same as the first layer GP1 (e.g., may be substantially the same as the first layer GP1), but rotated 90 degrees on a plane.

[0118] The reference area A0 at (e.g., in the middle or above) the pattern EU, where the first opening OP1 and the second opening OP2 are not provided (e.g., not overlapping with the first opening OP1 and the second opening OP2) may include (e.g., may form or may constitute) a first light emitting surface among a plurality of light emitting surfaces of the pattern EU. The first area A1 at (e.g., in the middle or above) the pattern EU, where the first opening OP1 is provided and the second opening OP2 is not provided (e.g., overlaps with the first opening OP1 and does not overlap with the second opening OP2) may include (e.g., may form or may constitute) a second light emitting surface. Similarly, at the pattern EU (e.g., in the middle or above), a second area A2 at which the second opening OP2 is provided (e.g., in the middle or above) and the first opening OP1 is not provided may include (e.g., may be formed or may be constituted of) a third light-emitting surface, and a third area A3 at the pattern EU (e.g., in the middle or above) at which the first opening OP1 and the second opening OP2 are provided (e.g., in the middle or above) (e.g., overlapping with the first opening OP1 and the second opening OP2) may include (e.g., may be formed or may be constituted of) a fourth light-emitting surface.

[0119] In an embodiment, the second layer GP2 may have a thickness different from that of the first layer GP1. For example, the thickness of the second layer GP2 may be twice the thickness of the first layer GP1. The four areas A0 to A3 may provide four optical paths having different lengths from each other.

[0120] Although reference Fig. 7A An embodiment in which the first layer GP1 and the second layer GP2 include the first opening OP1 and the second opening OP2, respectively, is described, but the present disclosure is not limited thereto. Fig. 6A As described, the first layer GP1 may include the first sub-pattern GP_P1 instead of the first opening OP1, and the second layer GP2 may include the second sub-pattern GP_P2 instead of the second opening OP2.

[0121] refer to Figure 7B , the speckle reducer 420_3 (eg, an optical path difference generator) and Fig. 7A The difference between the speckle reducer 420_2 shown in FIG. 4 and FIG. 5 is that the speckle reducer 420_3 may further include a third layer GP3 and a fourth layer GP4.

[0122] The third layer GP3 may include a third opening OP3, and the fourth layer GP4 may include a fourth opening OP4. The third opening OP3 and the fourth opening OP4 may be the same or substantially the same as the first opening OP1 and the second opening OP2, respectively (e.g., may be substantially the same or similar to the first opening OP1 and the second opening OP2), and therefore, a repeated description thereof may not be repeated. The third opening OP3 and the fourth opening OP4 may overlap the first opening OP1 and the second opening OP2, respectively.

[0123] At the pattern EU (e.g., in the middle or above), the fourth area A4 at which the first opening OP1 and the third opening OP3 are disposed (e.g., in the middle or above), may include (e.g., may form or may constitute) a fifth light-emitting surface among the plurality of light-emitting surfaces of the pattern EU. At the pattern EU (e.g., in the middle or above), the fifth area A5 at which the first opening OP1, the second opening OP2, and the third opening OP3 are disposed (e.g., in the middle or above), may include (e.g., may form or may constitute) a sixth light-emitting surface. At the pattern EU (e.g., in the middle or above), the sixth area A6 at which the second opening OP2 and the fourth opening OP4 are disposed (e.g., in the middle or above), may include (e.g., may form or may constitute) a seventh light-emitting surface of the pattern EU. Similarly, at the pattern EU (e.g., in the middle or above), the seventh area A7 where the first opening OP1, the second opening OP2 and the fourth opening OP4 are arranged (e.g., in the middle or above) may include (e.g., may form or may constitute) the eighth light-emitting surface of the pattern EU, and at the pattern EU (e.g., in the middle or above), the eighth area A8 where the first opening OP1, the second opening OP2, the third opening OP3 and the fourth opening OP4 are arranged (e.g., in the middle or above) may include (e.g., may form or may constitute) the ninth light-emitting surface of the pattern EU.

[0124] When the first to fourth layers GP1 to GP4 have different thicknesses from each other (eg, when the thickness of the upper layer is twice the thickness of the lower layer), the nine areas A0 to A8 may provide eight optical paths having different lengths from each other.

[0125] Although reference Figure 7B An embodiment in which the third layer GP3 and the fourth layer GP4 include the third opening OP3 and the fourth opening OP4, respectively, is described, but the present disclosure is not limited thereto. Fig. 6A As described, the third layer GP3 may include the third sub-pattern GP_P3 instead of the third opening OP3, and the fourth layer GP4 may include the fourth sub-pattern GP_P4 instead of the fourth opening OP4.

[0126] Figure 8 It is shown that the Figure 5 FIG. 4 is a diagram of another example of a speckle reducer in a display device shown in FIG. Figure 8 It is shown in Fig. 6A 4 is a side view of a corresponding speckle reducer 420_4 of the speckle reducer 420.

[0127] refer to Figure 5 , Fig. 6A and Figure 8 , Figure 8 The speckle reducer 420_4 shown in FIG. Fig. 6A The difference of the speckle reducer 420_4 shown in FIG. 4 may be that the pattern EU included in the speckle reducer 420_4 may correspond to the light emitting elements LD1 to LD4 (eg, see Figure 5 )

[0128] In addition, the sizes of the first sub-pattern GP_P1 and the second sub-pattern GP_P2 in the streak reducer 420_4 may be different from Fig. 6A In addition to the size of the first sub-pattern GP_P1 and the second sub-pattern GP_P2 of the speckle reducer 420, the speckle reducer 420_4 is Fig. 6A The speckle reducer 420 shown in FIG. 4 is the same or substantially the same (eg, substantially the same or similar) as that shown in FIG. 4 , and thus, a redundant description thereof may not be repeated.

[0129] In the pattern EU, each of the first sub-pattern GP_P1 and the second sub-pattern GP_P2 may be symmetrical to each other with respect to (eg, about) the second reference line LREF2. Figure 3 The optical path difference generator 121 described above may be formed between the first reference line LREF1 and the second reference line LREF2. Figure 3 The described optical path difference generator 121 may be formed between the second reference line LREF2 and the third reference line LREF3 to be reversed in the second direction DR2.

[0130] As mentioned above Figure 8 As described, the pattern EU of the speckle reducer 420_4 may correspond to two pixels in the second direction DR2.

[0131] Fig.9A and Fig. 9B It is shown that the Figure 5 FIG. 4 is a diagram of another example of a speckle reducer in a display device shown in FIG. Fig.9A A side view of a speckle reducer 420_5 (eg, an optical path difference generator) is shown in FIG. Fig. 9B A plan view of speckle reducer 420_5 is shown in FIG.

[0132] refer to Figure 5 , Fig.9Aand Fig. 9B , the speckle reducer 420_5 may include a first layer GP1, a second layer GP2, and a third layer GP3.

[0133] The first layer GP1 may include a first opening OP1. The first opening OP1 may have a width (e.g., a specific width or a predetermined width) in the second direction DR2, may extend in the third direction DR3, and may be repeatedly arranged along the second direction DR2. The first opening OP1 may be disposed corresponding to two pixels in the second direction DR2 (e.g., between the first reference line LREF1 and the third reference line LREF3). However, the present disclosure is not limited thereto.

[0134] The second layer GP2 may include a second opening OP2. The second opening OP2 may have a width (e.g., a specific width or a predetermined width) in the second direction DR2, may extend in the third direction DR3, and may be repeatedly arranged along the second direction DR2. The width of the second opening OP2 in the second direction DR2 may be equal to or substantially equal to the width of the first opening OP1 in the second direction DR2. The second opening OP2 may partially overlap with the first opening OP1 in the first direction DR1. In other words, the second opening OP2 may be disposed to partially stagger the first opening OP1 (e.g., partially not overlap with the first opening OP1).

[0135] Similarly, the third layer GP3 may include a third opening OP3. The third opening OP3 may have a width (e.g., a specific width or a predetermined width) in the second direction DR2, may extend in the third direction DR3, and may be repeatedly arranged along the second direction DR2. The width of the third opening OP3 in the second direction DR2 may be equal to or substantially equal to the width of the first opening OP1 in the second direction DR2. The third opening OP3 may partially overlap with the second opening OP2 in the first direction DR1, and may partially overlap with the first opening OP1 (or not overlap with the first opening OP1). In other words, the first opening OP1, the second opening OP2, and the third opening OP3 may be arranged to be partially staggered (e.g., partially non-overlapping) from each other.

[0136] refer to Figure 3 The described optical path difference generator 121 may be disposed between each of the reference lines LREF1 to LREF5 .

[0137] Fig.10 It is shown that the Figure 5 FIG. 4 is a diagram of another example of a speckle reducer in a display device shown in FIG. Fig.10 A side view of a speckle reducer 420_6 (eg, an optical path difference generator) is shown.

[0138] refer to Figure 5 and Fig.10 , the speckle reducer 420_6 may include a first layer GP1_1 , a second layer GP2_1 , and a third layer GP3_1 .

[0139] The first layer GP1_1 , the second layer GP2_1 , and the third layer GP3_1 may have different thicknesses from each other.

[0140] For example, the first thickness T1 of the first layer GP1_1 may correspond to Figure 5 The first light emitting element LD1 described above emits light (eg, red light or a wavelength of red light). The second thickness T2 of the second layer GP2_1 may correspond to the wavelength T2 of the first light emitting element LD1. Figure 5 The light emitted by the second light emitting element LD2 described above (eg, green light or a wavelength of green light), and the third thickness T3 of the third layer GP3_1 may correspond to the value from the reference Figure 5 The third light emitting element LD3 is described to emit light (eg, blue light or a wavelength of blue light).

[0141] The first layer GP1_1 may include a first opening OP1. The first opening OP1 may (eg, corresponding to the reference Figure 5 The first light emitting element LD1 described above is disposed between the first reference line LREF1 and the second reference line LREF2. The first wave CL_W1 transmitted through the first opening OP1 between the first reference line LREF1 and the second reference line LREF2 may have an optical path difference (or phase difference) corresponding to the first thickness T1 relative to the reference wave CL_W0 transmitted while avoiding the first opening OP1.

[0142] The second layer GP2_1 may include a second opening OP2. The second opening OP2 may (eg, corresponding to the reference Figure 5 The second light emitting element LD2 is disposed between the second reference line LREF2 and the third reference line LREF3. The second wave CL_W2 transmitted through the second opening OP2 between the second reference line LREF2 and the third reference line LREF3 may have an optical path difference (or phase difference) corresponding to the second thickness T2 relative to the reference wave CL_W0.

[0143] The third layer GP3_1 may include a third opening OP3. The third opening OP3 may (eg, corresponding to the reference Figure 5 The third light emitting element LD3 is disposed between the third reference line LREF3 and the fourth reference line LREF4. The third wave CL_W3 transmitted through the third opening OP3 between the third reference line LREF3 and the fourth reference line LREF4 may have an optical path difference (or phase difference) corresponding to the third thickness T3 relative to the reference wave CL_W0.

[0144] In other words, the speckle reducer 420_6 can provide the corresponding light emitting elements LD1 to LD3 (eg, see Figure 5 ) of different patterns (e.g., different optical structures or different unit optical structures) EU (e.g., see Figure 5 ).

[0145] In the backlight device and the holographic 3D image display device according to one or more embodiments of the present disclosure, different light paths may be provided for the coherent light passing through the optical path difference generator. Different phases may be provided to the coherent light transmitted through the optical path difference generator, and due to the different phases, different speckles overlapping each other may be generated. Therefore, the speckle brightness may be reduced, and the speckle (e.g., any speckle) may not be observed (e.g., may not be easily observed or may not be easily noticed).

[0146] Although various exemplary embodiments have been disclosed herein, and although specific terms are used to describe the exemplary embodiments, they are used and interpreted only in a general and descriptive sense, and not for limiting purposes. In some cases, as will be apparent to one of ordinary skill in the art, unless otherwise specifically noted, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments. Therefore, it will be understood by those skilled in the art that various modifications and changes in form and / or detail may be made to the exemplary embodiments disclosed herein without departing from the spirit and scope of the present disclosure as set forth in the appended claims and their equivalents.

Claims

1. A backlight device for a holographic three-dimensional image, comprising: a light source configured to emit coherent light; an optical path difference generator, located on the light source, the optical path difference generator comprising an incident surface and a plurality of light emitting surfaces, the light emitting surfaces being parallel to the incident surface and having different separation distances from the incident surface; A condenser, located on the optical path difference generator; a diffuser, located on the concentrator; as well as A collimator is located on the diffuser.

2. The backlight device according to claim 1, wherein: The optical path difference generator comprises: First level; and a second layer, located on the first layer, the second layer partially overlapping the first layer, wherein a portion of the first layer is exposed by the second layer and includes a first light emitting surface among the plurality of light emitting surfaces, and At least a portion of the second layer overlaps with the first layer and includes a second light emitting surface among the plurality of light emitting surfaces.

3. The backlight device according to claim 2, wherein: The thickness of the second layer is greater than the temporal coherence length of the coherent light.

4. The backlight device according to claim 3, wherein: The temporal coherence length is defined as the distance the coherent light travels during the delay time, and Here, the delay time is defined as the amount of time until the coherence between the coherent light and the delayed light, which is obtained by delaying the coherent light by the delay time, decreases to a value of 0.

5. The backlight device according to claim 2, wherein: In a plan view, an area of ​​the second layer is smaller than an area of ​​the first layer.

6. A display device for holographic three-dimensional images, comprising: Backlight device; as well as A light modulator is located on the backlight device. Wherein, the backlight device comprises: a light source configured to emit coherent light; and an optical path difference generator, located on the light source, the optical path difference generator comprising an incident surface and a plurality of light emitting surfaces, the light emitting surfaces being parallel to the incident surface and having different separation distances from the incident surface, The light modulator expresses a three-dimensional image by modulating the light passing through the optical path difference generator.

7. The display device according to claim 6, wherein: The light source comprises: A display panel including a plurality of pixels, each of the pixels including a light emitting element; and a first collimator, located on the display panel, wherein the first collimator comprises a plurality of collimating lenses corresponding to the pixels respectively; wherein the optical path difference generator includes a pattern, the pattern includes each of the light emitting surfaces, the pattern is repeatedly arranged, and The pattern of the optical path difference generator corresponds to at least one pixel among the plurality of pixels.

8. The display device according to claim 7, wherein: The patterns include: A first sub-pattern located at the first layer; and a second sub-pattern located at a second layer different from the first layer, wherein an area of ​​the second sub-pattern is smaller than an area of ​​the first sub-pattern, wherein a portion of the first sub-pattern is exposed by the second sub-pattern and includes a first light emitting surface among the plurality of light emitting surfaces, and At least a portion of the second sub-pattern overlaps with the first sub-pattern and includes a second light emitting surface among the plurality of light emitting surfaces.

9. The display device according to claim 7, wherein: The patterns include: a first layer having a first opening; and a second layer, located on the first layer, the second layer having a second opening overlapping the first opening, wherein a portion of the first layer is exposed by the second opening and includes a first light emitting surface among the plurality of light emitting surfaces, and At least a portion of the second layer does not overlap with the first opening and includes a second light emitting surface among the plurality of light emitting surfaces.

10. The display device according to claim 7, wherein: The optical path difference generator includes a first layer and a second layer located on the first layer; The first layer has first openings having a width, the first openings extending in a first direction and repeatedly arranged along a second direction intersecting the first direction; as well as The second layer includes second openings having a width, the second openings extending in the second direction, and being repeatedly arranged along the first direction.

Images