Light source device and display device

Abstract

To improve uniformity of brightness.SOLUTION: A display device comprises: a first transparent substrate; a second transparent substrate including a first surface and a second surface different from the first surface; a liquid crystal layer positioned between the first transparent substrate and the second transparent substrate, and containing polymer dispersion type liquid crystal; a light emission part configured to emit illumination light for illuminating the liquid crystal layer; and a diffraction optical element facing the first surface, provided in a position overlapping the liquid crystal layer, and configured to diffract the illumination light.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a light source device and a display device. [Background technology]

[0002] In recent years, various display devices using polymer dispersed liquid crystal (Polymer Dispersed Liquid Crystal), which can be switched between a scattering state and a transparent state, have been proposed. For example, a display device includes a display panel including the polymer dispersed liquid crystal and a light source disposed along the side of a transparent substrate. In such display devices, brightness tends to decrease with increasing distance from the light source, and therefore, there is a demand for improved brightness uniformity. On the other hand, there is known a technique for guiding an image displayed at a position distant from the user and projecting the image onto the user's eyes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-32411 A [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-132328 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the embodiments is to provide a display device and a light source device that can improve the uniformity of luminance. [Means for solving the problem]

[0005] According to one embodiment, the display device comprises: The optical element includes a first transparent substrate, a second transparent substrate having a first surface and a second surface different from the first surface, a liquid crystal layer located between the first transparent substrate and the second transparent substrate and containing a polymer dispersed liquid crystal, a light emitting unit configured to emit illumination light for illuminating the liquid crystal layer, and a diffractive optical element located opposite the first surface and not overlapping with the liquid crystal layer, configured to diffract the illumination light.

[0006] According to one embodiment, the light source device comprises: The optical element includes a transparent substrate having a first surface and a second surface different from the first surface, a light-emitting unit configured to emit illumination light for illuminating the transparent substrate, and a diffractive optical element facing the first surface and configured to diffract the illumination light. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a plan view showing a first configuration example of a display device 1. As shown in FIG. [Figure 2] FIG. 2 is a cross-sectional view of the display device 1 taken along the line AB shown in FIG. [Figure 3] FIG. 3 is a diagram for explaining how part of the illumination light LI is diffracted. [Figure 4] FIG. 4 is a plan view showing a second configuration example of the display device 1. As shown in FIG. [Figure 5] FIG. 5 is a plan view showing a third configuration example of the display device 1. As shown in FIG. [Figure 6] FIG. 6 is a diagram for explaining a diffractive optical element OE applicable to the third configuration example. [Figure 7] FIG. 7 is a diagram for explaining another diffractive optical element OE that can be applied to configuration example 3. In FIG. [Figure 8] FIG. 8 is a plan view showing a fourth configuration example of the display device 1. As shown in FIG. [Figure 9] FIG. 9 is a plan view showing a fifth configuration example of the display device 1. As shown in FIG. [Figure 10] FIG. 10 is a plan view showing a sixth configuration example of the display device 1. As shown in FIG. [Figure 11]FIG. 11 is a cross-sectional view of the display device 1 taken along the line AB shown in FIG. [Figure 12] FIG. 12 is a plan view showing a seventh configuration example of the display device 1. As shown in FIG. [Figure 13] FIG. 13 is a plan view showing an eighth configuration example of the display device 1. As shown in FIG. [Figure 14] FIG. 14 is a plan view showing a configuration example 9 of the display device 1. As shown in FIG. [Figure 15] FIG. 15 is a diagram showing the light guide LG shown in FIG. [Figure 16] FIG. 16 is a plan view showing a configuration example 10 of the display device 1. As shown in FIG. [Figure 17] FIG. 17 is a plan view showing an eleventh configuration example of the display device 1. As shown in FIG. [Figure 18] FIG. 18 is a plan view showing a configuration example 12 of the display device 1. As shown in FIG. [Figure 19] FIG. 19 is a cross-sectional view showing an example of the configuration of the diffractive optical element OE. [Figure 20] FIG. 20 is a diagram for explaining Application Example 1 of the liquid crystal element. [Figure 21] FIG. 21 is a diagram illustrating a second application example of the liquid crystal element. [Figure 22] FIG. 22 is a diagram illustrating a third application example of the liquid crystal element. [Figure 23] FIG. 23 is a diagram illustrating a fourth application example of the liquid crystal element. [Figure 24] FIG. 24 is a cross-sectional view showing an example of the configuration of the display device 1 taken along line CD shown in FIG. [Figure 25] FIG. 25 is a cross-sectional view showing another example of the configuration of the display device 1 taken along the line CD shown in FIG. [Figure 26] FIG. 26 is a plan view showing the first modification. [Figure 27] FIG. 27 is a plan view showing the second modification. [Figure 28] FIG. 28 is a plan view showing the third modification. [Figure 29] FIG. 29 is a plan view showing the fourth modification. [Figure 30]FIG. 30 is a plan view showing the fifth modification. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment will be described with reference to the drawings. The disclosure is merely an example, and appropriate modifications that a person skilled in the art can easily make while maintaining the gist of the invention are naturally included within the scope of the present invention. Furthermore, the drawings may be schematic in terms of the width, thickness, shape, etc. of each part compared to the actual embodiment for the sake of clarity, but these are merely examples and are not intended to limit the interpretation of the present invention. Furthermore, in this specification and each drawing, components that perform the same or similar functions as those described above with reference to the previous drawings are designated by the same reference numerals, and redundant detailed descriptions may be omitted as appropriate.

[0009] In addition, to facilitate understanding, the drawings will depict mutually orthogonal X, Y, and Z axes as necessary. The direction along the X axis is referred to as the first direction X, the direction along the Y axis is referred to as the second direction Y, and the direction along the Z axis is referred to as the third direction Z. Viewing various elements parallel to the third direction Z is referred to as a planar view. Terms referring to the relative positions of two or more components, such as "on top," "above," "between," and "opposite," include not only cases where the two or more components are in direct contact with each other, but also cases where they are separated from each other by a gap or another component. The positive direction of the Z axis is referred to as "up" or "above."

[0010] FIG. 1 is a plan view showing a first configuration example of a display device 1. As shown in FIG.

[0011] The display device 1 includes a transparent substrate 10, a transparent substrate 20, a liquid crystal layer LC, a seal SE, a light-emitting unit LE, and a diffractive optical element OE. The transparent substrate 10 and the transparent substrate 20 are each formed in a flat plate shape parallel to an XY plane defined by a first direction X and a second direction Y, and overlap each other in a planar view. The transparent substrate 10 extends further in the second direction Y than the transparent substrate 20. In the illustrated example, the transparent substrate 10 and the transparent substrate 20 are both formed in a quadrangle, but this is not limiting. For example, the transparent substrate 10 and the transparent substrate 20 may have any shape other than a quadrangle, such as a polygon, a circle, an ellipse, or a semicircle.

[0012] The liquid crystal layer LC is located between the transparent substrate 10 and the transparent substrate 20 and is sealed with a seal SE. In the enlarged schematic example shown in FIG. 1, the liquid crystal layer LC comprises a polymer-dispersed liquid crystal including a polymer PL and liquid crystal molecules LM. In one example, the polymer PL is a liquid crystal polymer and is formed in stripes extending along the first direction X. The liquid crystal molecules LM are dispersed in the gaps between the polymer PL and are oriented with their major axes aligned along the first direction X. Each of the polymer PL and the liquid crystal molecules LM has optical anisotropy or refractive index anisotropy. The responsiveness of the polymer PL to an electric field is lower than that of the liquid crystal molecules LM.

[0013] In one example, the alignment direction of the polymer PL hardly changes regardless of whether an electric field is applied or not. On the other hand, the alignment direction of the liquid crystal molecules LM changes in response to an electric field when a high voltage equal to or greater than a threshold value is applied to the liquid crystal layer LC. When no voltage is applied to the liquid crystal layer LC, the optical axes of the polymer PL and the liquid crystal molecules LM are parallel to each other, and light incident on the liquid crystal layer LC is transmitted through the liquid crystal layer LC with almost no scattering within the liquid crystal layer LC (transparent state). When a voltage is applied to the liquid crystal layer LC, the optical axes of the polymer PL and the liquid crystal molecules LM intersect with each other, and light incident on the liquid crystal layer LC is scattered within the liquid crystal layer LC (scattered state).

[0014] The configuration of the polymer dispersed liquid crystal including the polymer PL and the liquid crystal molecules LM is not limited to the above example.

[0015] The display device 1 has a display area DA for displaying an image. The display area DA includes a plurality of pixels PX arranged in a matrix in a first direction X and a second direction Y. In the illustrated example, the display area DA is formed in a rectangular shape as indicated by the dashed lines, but is not limited to this. For example, the display area DA may have any shape other than a rectangular shape, such as a polygon, a circle, an ellipse, or a semicircle.

[0016] As shown enlarged in FIG. 1, each pixel PX includes a switching element SW, a pixel electrode PE, a common electrode CE, a liquid crystal layer LC, etc. The switching element SW is formed, for example, by a thin film transistor (TFT) and is electrically connected to a scanning line G and a signal line S. The scanning line G extends in a first direction X and is electrically connected to the switching element SW in each of the pixels PX aligned in the first direction X. The signal line S extends in a second direction Y, intersecting the scanning line G, and is electrically connected to the switching element SW in each of the pixels PX aligned in the second direction Y. The pixel electrode PE is electrically connected to the switching element SW. Each pixel electrode PE faces the common electrode CE, and drives the liquid crystal layer LC (particularly, liquid crystal molecules LM) by an electric field generated between the pixel electrode PE and the common electrode CE. The capacitance CS is formed, for example, between an electrode having the same potential as the common electrode CE and an electrode having the same potential as the pixel electrode PE.

[0017] The scanning lines G, signal lines S, switching elements SW, and pixel electrodes PE are formed between a transparent substrate 10 and a liquid crystal layer LC. A common electrode CE is formed between the transparent substrate 20 and the liquid crystal layer LC.

[0018] The IC chip CP and a flexible printed circuit board (not shown) are mounted on the transparent substrate 10.

[0019] The light emitting unit LE is configured to emit illumination light LI for illuminating the liquid crystal layer LC. In configuration example 1, the light emitting unit LE faces the transparent substrate 20 and overlaps the transparent substrate 20 in a plan view.

[0020] The diffractive optical element OE is provided at a position where it does not overlap with the liquid crystal layer LC. In configuration example 1, the diffractive optical element OE faces the transparent substrate 20 and overlaps with the transparent substrate 20 and the light-emitting unit LE in a planar view. Furthermore, the diffractive optical element OE and the liquid crystal layer LC are aligned in the second direction Y in a planar view.

[0021] In the illustrated example, the two light-emitting units LE are arranged side by side at an interval in the first direction X. The diffractive optical element OE is formed in a strip shape extending in the first direction X. In plan view, the two light-emitting units LE overlap at both ends of the diffractive optical element OE. Note that there may be only one light-emitting unit LE.

[0022] The diffractive optical element OE is configured to diffract illumination light LI emitted from the light-emitting unit LE. Hereinafter, the grating surfaces arranged at a constant interval in the diffractive optical element OE will be referred to as the diffractive surface DS. In the diffractive optical element OE, a portion of the illumination light LI is diffracted by the diffractive surface DS. The diffractive surface DS on one end side (left side in the figure) of the diffractive optical element OE is tilted in a different direction from the diffractive surface DS on the other end side (right side in the figure) of the diffractive optical element OE.

[0023] FIG. 2 is a cross-sectional view of the display device 1 taken along the line AB shown in FIG.

[0024] The transparent substrate 20 has a main surface 20A facing the transparent substrate 10 in the third direction Z, and a main surface 20B opposite to the main surface 20A.

[0025] The diffractive optical element OE faces the main surface 20A in the third direction Z. The diffractive optical element OE is, for example, a thin film formed directly on the main surface 20A. The diffractive optical element OE may be formed as a sheet and bonded to the main surface 20A. An air layer is interposed between the diffractive optical element OE and the transparent substrate 10.

[0026] The light-emitting unit LE faces the main surface 20B in the third direction Z. Such a light-emitting unit LE includes a light-emitting element and is configured to emit illumination light LI toward the transparent substrate 20. The two light-emitting units LE face the diffractive optical element OE in the third direction Z, respectively, via the transparent substrate 20. In the illustrated example, the light-emitting unit LE emits illumination light LI in a direction oblique to the normal to the main surface 20B. Such a light-emitting unit LE can be realized by adding a light control element (for example, various optical elements such as a diffraction element) that controls the traveling direction of light emitted from the light-emitting element.

[0027] The illumination light LI emitted from the light-emitting unit LE is incident on the transparent substrate 20, and then propagates while repeatedly being totally reflected in the laminate of the transparent substrate 20 and the diffractive optical element OE. Then, a portion of the illumination light LI is diffracted in the second direction Y by the diffractive optical element OE.

[0028] FIG. 3 is a diagram for explaining how part of the illumination light LI is diffracted.

[0029] In the illustrated example, the diffractive optical element OE extends in a first direction X, has a width W along a second direction Y, and has a thickness T along a third direction Z. In such a diffractive optical element OE, the diffractive surface DS is an inclined surface that intersects with all of the first direction X, the second direction Y, and the third direction Z. In the diffractive optical element OE, the illumination light LI propagated along the first direction X is diffracted at the diffractive surface DS along the second direction Y. As described with reference to FIG. 1 , the diffractive optical element OE and the liquid crystal layer LC are aligned in the second direction Y, and therefore the illumination light LI diffracted in the second direction Y at the diffractive surface DS can illuminate the liquid crystal layer LC.

[0030] The orientation of the diffractive surface DS can be freely set. Furthermore, the diffraction efficiency of the diffractive optical element OE can be freely set. Therefore, the illumination light LI can be diffracted in a desired direction with a desired brightness. Therefore, regardless of the shape of the transparent substrate 20 or the shape of the display area DA, the illumination light LI reaches the entire display area DA with a desired amount of light, thereby improving brightness uniformity.

[0031] FIG. 4 is a plan view showing a second configuration example of the display device 1. As shown in FIG.

[0032] Configuration Example 2 differs from Configuration Example 1 in that the diffractive optical element OE extends in the second direction Y.

[0033] As in the first configuration example, the light emitting unit LE faces the transparent substrate 20 and overlaps the transparent substrate 20 in a plan view.

[0034] The diffractive optical element OE is provided at a position not overlapping with the liquid crystal layer LC, faces the transparent substrate 20, and overlaps with the transparent substrate 20 and the light-emitting unit LE in a planar view. In addition, the diffractive optical element OE and the liquid crystal layer LC are aligned in the first direction X in a planar view.

[0035] In the illustrated example, the two light-emitting units LE are arranged side by side at an interval in the first direction X. Furthermore, the two diffractive optical elements OE are arranged side by side at an interval in the first direction X. The liquid crystal layer LC is located between the two diffractive optical elements OE in a plan view. The two light-emitting units LE are each superimposed on one end of the diffractive optical element OE. Note that, similar to configuration example 1, the light-emitting units LE may be superimposed on both end portions of one diffractive optical element OE.

[0036] The diffractive surface DS of the diffractive optical element OE located on the left side of the figure is tilted in a different direction from the diffractive surface DS of the diffractive optical element OE located on the right side of the figure. When the illumination light LI emitted from the light-emitting unit LE reaches the diffractive optical element OE, it is diffracted by the diffractive surface DS in the first direction X and can illuminate the liquid crystal layer LC.

[0037] Even in such Configuration Example 2, the same effects as those in Configuration Example 1 can be obtained.

[0038] FIG. 5 is a plan view showing Configuration Example 3 of the display device 1.

[0039] [[ID=​​​​​​​​​​​​​​​​​​​​​​​​The diffractive optical element OE extends in the second direction Y and has a width W along the first direction X. In the diffractive optical element OE, the width W1 of one end portion where the light emitting portion LE overlaps is smaller than the width W2 of the other end portion where the light emitting portion LE does not overlap (W1 < W2). Thereby, it is possible to provide the diffractive optical element OE in which the diffraction efficiency at one end portion is smaller than the diffraction efficiency at the other end portion.

[0046] Note that, not limited to the examples shown in FIGS. 6 and 7, for example, the diffraction efficiency may be adjusted according to the refractive index distribution in the diffractive optical element OE.

[0047] FIG. 8 is a plan view showing Configuration Example 4 of the display device 1.

[0048] Configuration Example 4 is different from Configuration Example 3 in that the display device 1 further includes a light source unit LU. The light source unit LU is arranged along the side surface 20S extending in the first direction X of the transparent substrate 20. The light source unit LU includes a plurality of light emitting elements LD arranged in the first direction X. These light emitting elements LD are each configured to emit illumination light LI toward the side surface 20S.

[0049] In such Configuration Example 4, illumination light LI for illuminating the liquid crystal layer LC from three directions is formed by the two light emitting portions LE and the light source unit LU, and the uniformity of the luminance in the display region DA can be further improved.

[0050] FIG. 9 is a plan view showing Configuration Example 5 of the display device 1.

[0051] In Configuration Example 5, the display device 1 is formed in a rectangular shape having a long side in the first direction X. The three diffractive optical elements OE are each formed in a strip shape extending in the second direction Y and are arranged side by side at intervals in the first direction X. The diffractive optical element OE located at the center intersects the display region DA or the liquid crystal layer LC in a plan view.

[0052] In the illustrated example, the three light-emitting units LE are arranged at intervals in the first direction X and overlap one end of the diffractive optical element OE. The light-emitting unit LE located in the center may be omitted. The light source unit LU is disposed along the side surface 20S of the transparent substrate 20.

[0053] In such a display device 1, illumination light LI emitted from the left light-emitting element LE is diffracted to the right by the diffractive optical element OE. Similarly, illumination light LI emitted from the right light-emitting element LE is diffracted to the left by the diffractive optical element OE. Furthermore, illumination light LI emitted from the central light-emitting element LE or light source unit LU is diffracted to the left and right by the diffractive optical element OE. This allows for improved brightness uniformity even in a display device 1 having a horizontally elongated display area DA.

[0054] In the above configuration examples 1 to 5, the main surface (first main surface) 20A corresponds to the first surface, and the main surface (second main surface) 20B corresponds to the second surface. The main surface 20A and the main surface 20B are both surfaces along the XY plane.

[0055] FIG. 10 is a plan view showing a sixth configuration example of the display device 1. As shown in FIG.

[0056] Configuration Example 6 differs from Configuration Example 1 in that the light-emitting unit LE faces the side surface 20S of the transparent substrate 20. In a plan view, the diffractive optical element OE overlaps the transparent substrate 20, and the light-emitting unit LE overlaps neither the transparent substrate 20 nor the diffractive optical element OE.

[0057] In the illustrated example, the two light-emitting units LE are arranged side by side at an interval in the first direction X. The diffractive optical element OE is formed in a strip shape extending in the first direction X and is located between the two light-emitting units LE. In other words, one of the two light-emitting units LE is located on one end side of the diffractive optical element OE, and the other is located on the other end side of the diffractive optical element OE. Note that there may be only one light-emitting unit LE.

[0058] FIG. 11 is a cross-sectional view of the display device 1 taken along the line AB shown in FIG.

[0059] The transparent substrate 20 has a main surface 20A facing the transparent substrate 10 in the third direction Z, and a side surface 20S intersecting with the main surface 20A. The side surface 20S here is a surface along the YZ plane defined by the second direction Y and the third direction Z.

[0060] The diffractive optical element OE faces the main surface 20A in the third direction Z. Between the diffractive optical element OE and the transparent substrate 10, an air layer is interposed.

[0061] The light-emitting unit LE faces the side surface 20S in the first direction X and is configured to emit illumination light LI toward the transparent substrate 20. After being incident on the transparent substrate 20, the illumination light LI emitted from the light-emitting unit LE propagates while repeatedly being totally reflected in the laminate of the transparent substrate 20 and the diffractive optical element OE. Then, a portion of the illumination light LI is diffracted in the diffractive optical element OE along the second direction Y.

[0062] In this configuration example 6, the same effects as those in the above configuration example 1 can be obtained.

[0063] FIG. 12 is a plan view showing a seventh configuration example of the display device 1. As shown in FIG.

[0064] Configuration Example 7 differs from Configuration Example 6 in that the diffractive optical element OE extends in the second direction Y.

[0065] The light-emitting portion LE faces a side surface 20S of the transparent substrate 20 in the second direction Y. In the seventh configuration example, the side surface 20S that the light-emitting portion LE faces is a surface along the XZ plane defined by the first direction X and the third direction Z.

[0066] The diffractive optical element OE is provided at a position not overlapping with the liquid crystal layer LC, faces the transparent substrate 20, and overlaps with the transparent substrate 20 in a planar view. In addition, the diffractive optical element OE and the liquid crystal layer LC are aligned in the first direction X in a planar view.

[0067] In the illustrated example, the two light-emitting units LE are arranged side by side in the first direction X with a gap therebetween. The two diffractive optical elements OE are also arranged side by side in the first direction X with a gap therebetween. The liquid crystal layer LC is located between the two diffractive optical elements OE in a plan view. The two light-emitting units LE are each located on one end side of the diffractive optical element OE. Note that, similar to configuration example 6, the light-emitting units LE may be located on one end side and the other end side of one diffractive optical element OE.

[0068] In the seventh configuration, the same effects as those in the first configuration can be obtained.

[0069] FIG. 13 is a plan view showing an eighth configuration example of the display device 1. As shown in FIG.

[0070] Configuration Example 8 differs from Configuration Example 7 in that the diffraction efficiency of the diffractive optical element OE differs between one end side and the other end side. That is, in the diffractive optical element OE, the diffraction efficiency at one end close to the light-emitting unit LE is lower than the diffraction efficiency at the other end farther away from the light-emitting unit LE. Such a diffractive optical element OE is configured similarly to the diffractive optical element described in Configuration Example 3. For example, as described with reference to FIG. 6, a diffractive optical element OE having a configuration in which the thickness T1 of one end is smaller than the thickness T2 of the other end is applicable. Alternatively, as described with reference to FIG. 7, a diffractive optical element OE having a configuration in which the width W1 of one end is smaller than the width W2 of the other end is applicable.

[0071] In this configuration example 8 as well, the uniformity of luminance can be improved.

[0072] In Configuration Example 8, a light source unit LU may be further added as described in Configuration Example 4. Furthermore, as described in Configuration Example 5, a diffractive optical element OE that intersects with the display area DA may be added, similar to the display device 1 having a rectangular display area DA.

[0073] In the above-described configuration examples 6 to 8, the main surface (first main surface) 20A corresponds to the first surface, and the side surface 20S corresponds to the second surface. The main surface 20A is a surface along the XY plane. The side surface 20S is a surface along the YZ plane in configuration example 6, and a surface along the XZ plane in configuration examples 7 and 8.

[0074] FIG. 14 is a plan view showing a configuration example 9 of the display device 1. As shown in FIG.

[0075] In configuration example 9, the display device 1 further includes a transparent light guide LG. The light guide LG extends in the first direction X and is located between the diffractive optical element OE and the transparent substrate 20 in the second direction Y. The light guide LG is made of, for example, glass or resin. The light guide LG has a side surface LGS1 facing the side surface 20S of the transparent substrate 20. For example, the light guide LG is bonded to the side surface 20S.

[0076] The diffractive optical element OE extends in the first direction X and faces a side surface of the light guide LG in the second direction Y. The diffractive optical element OE also faces a side surface 20S of the transparent substrate 20 via the light guide LG. The light emitting unit LE faces the other side surface of the light guide LG. In a plan view, the light emitting unit LE overlaps both end portions of the light guide LG, and the diffractive optical element OE does not overlap the light guide LG. The light guide LG will be described in detail below.

[0077] FIG. 15 is a diagram showing the light guide LG shown in FIG.

[0078] The light guide LG has a side surface LGS1, a side surface LGS2, a side surface LGS3, an end surface LGE1, and an end surface LGE2. The side surface LGS2 is a surface that intersects with the side surface LGS1. The side surface LGS3 is a surface that faces the side surface LGS1 and also intersects with the side surface LGS2. The end surface LGE1 is a surface that intersects with the side surface LGS1. The end surface LGE2 is a surface that faces the end surface LGE1 and also intersects with the side surface LGS1.

[0079] In the illustrated example, the light guide LG is formed as a rectangular parallelepiped extending in the first direction X. When the side surface LGS1 is a surface along the XZ plane, the side surface LGS2 is a surface along the XY plane, and the side surface LGS3 is a surface along the XZ plane. In addition, the end surfaces LGE1 and LGE2 are surfaces along the YZ plane.

[0080] The diffractive optical element OE faces the side surface LGS3 in the second direction Y. The diffractive optical element OE may be formed directly on the side surface LGS3, or may be bonded to the side surface LGS3.

[0081] The light-emitting unit LE faces the side surface LGS2 in the third direction Z. In the illustrated example, the two light-emitting units LE face both end portions of the side surface LGS2. Note that one light-emitting unit LE may face one end portion of the side surface LGS2.

[0082] The illumination light emitted from the light-emitting unit LE enters the light guide LG and then propagates through the light guide LG while repeatedly undergoing total reflection. After that, part of the illumination light is diffracted along the second direction Y by the diffractive optical element OE.

[0083] This provides the same effect as in the first configuration example.

[0084] FIG. 16 is a plan view showing a configuration example 10 of the display device 1. As shown in FIG.

[0085] Configuration Example 10 differs from Configuration Example 9 in that the light guide LG and the diffractive optical element OE extend in the second direction Y. The light guide LG is located between the diffractive optical element OE and the transparent substrate 20 in the first direction X, and is bonded to, for example, the side surface 20S along the YZ plane.

[0086] The light emitting element LE faces the light guide LG and overlaps the light guide LG in a plan view.

[0087] In the illustrated example, two light emitting units LE are arranged at an interval in the first direction X, two diffractive optical elements OE are arranged at an interval in the first direction X, and two light guides LG are arranged at an interval in the first direction X. The liquid crystal layer LC is located between the two light guides LG in a plan view. The two light emitting units LE are overlapped with one end of each light guide LG. Note that, similar to configuration example 9, the light emitting units LE may be overlapped with both end portions of one light guide LG.

[0088] In this configuration example 10 as well, the same effects as those in configuration example 1 can be obtained.

[0089] FIG. 17 is a plan view showing an eleventh configuration example of the display device 1. As shown in FIG.

[0090] Configuration Example 11 differs from Configuration Example 9 in that the light-emitting units LE face the end faces LGE1 and LGE2 of the light guide LG in the first direction X. The diffractive optical element OE faces the side face LGS3 of the light guide LG. In other words, the light guide LG and the diffractive optical element OE are located between the two light-emitting units LE.

[0091] In this configuration example 11 as well, the same effects as those in configuration example 1 can be obtained.

[0092] FIG. 18 is a plan view showing a configuration example 12 of the display device 1. As shown in FIG.

[0093] Configuration Example 12 differs from Configuration Example 10 in that the light emitting portion LE faces the end face LGE1 of the light guide LG. In this configuration example, the same effects as in the first configuration example can be obtained.

[0094] In the above configuration examples 9 to 12, the light guide LG is arranged between the transparent substrate 20 and the diffractive optical element OE, but the light guide LG may be omitted and the diffractive optical element OE may be formed directly on the side surface 20S of the transparent substrate 20 or may be adhered to the side surface 20S.

[0095] In addition, the side surface LGS2 corresponds to the second surface in Configuration Examples 9 and 10. In Configuration Examples 11 and 12, the end surface (first end surface) LGE1 and the end surface (second end surface) LGE2 correspond to the second surface.

[0096] The above-mentioned diffractive optical element OE is, for example, a holographic optical element, which has an interference fringe pattern and is configured to diffract a portion of incident light in a predetermined direction.

[0097] The diffractive optical element OE may also be a liquid crystal element containing cholesteric liquid crystal. The cholesteric liquid crystal contains a plurality of liquid crystal molecules arranged in a spiral that rotates in one direction. Such cholesteric liquid crystal is configured to diffract circularly polarized light in the same direction as the spiral direction and transmit circularly polarized light in the opposite direction to the spiral direction. The wavelength band of the circularly polarized light diffracted by the cholesteric liquid crystal is set according to the helical pitch and refractive index anisotropy of the cholesteric liquid crystal.

[0098] The following describes the case where the diffractive optical element OE is a liquid crystal element.

[0099] Fig. 19 is a cross-sectional view showing an example of the configuration of a diffractive optical element OE. Note that Fig. 19 shows an enlarged schematic view of the cholesteric liquid crystal in which a plurality of liquid crystal molecules are arranged in a spiral shape.

[0100] The diffractive optical element OE described in the above configuration examples 1 to 12 is bonded to, for example, the transparent substrate 20 or the light guide LG. The diffractive optical element OE includes a diffractive element OE1, a diffractive element OE2, and a diffractive element OE3. The diffractive elements OE1, OE2, and OE3 are stacked. The stacking order of the multiple diffractive elements is not limited to the example shown in the figure. The diffractive elements OE1, OE2, and OE3 are configured to diffract illumination light of different wavelength bands.

[0101] The diffraction element OE1 contains a cholesteric liquid crystal CL1. The cholesteric liquid crystal CL1 has a helical pitch P1. The helical pitch indicates one period of the helix (the layer thickness along the helical axis required for the liquid crystal molecules to rotate 360 ​​degrees).

[0102] The diffractive element OE2 includes a cholesteric liquid crystal CL2. The cholesteric liquid crystal CL2 has a helical pitch P2. The helical pitch P2 is different from the helical pitch P1 and is larger than the helical pitch P1 (P1). <P2)。

[0103] The diffractive element OE3 includes a cholesteric liquid crystal CL3. The cholesteric liquid crystal CL3 has a helical pitch P3. The helical pitch P3 is different from the helical pitch P1 and the helical pitch P2, and is larger than the helical pitch P2 here (P2 <P3)。

[0104] In the illustrated example, the cholesteric liquid crystals CL1, CL2, and CL3 are all twisted in the same direction, but any one of them may be twisted in a direction different from the other two.

[0105] In the diffractive optical element OE having such a configuration, for example, the diffractive element OE1 is configured to diffract, with a diffractive surface DS1, illumination light in a first wavelength band including a blue component from among the incident illumination light. The diffractive element OE2 is configured to diffract, with a diffractive surface DS2, illumination light in a second wavelength band including a green component from among the illumination light. The diffractive element OE3 is configured to diffract, with a diffractive surface DS3, illumination light in a third wavelength band including a red component from among the illumination light.

[0106] In this way, when a diffractive element is configured to diffract illumination light in a specific wavelength band, by using multiple diffractive elements with different diffracting wavelength bands, it is possible to diffract light across almost the entire visible light range. While the case where multiple diffractive elements are stacked has been described in Fig. 19, multiple diffractive elements may also be arranged side by side in a planar view. Furthermore, the diffractive optical element OE may include two diffractive elements, or may include four or more diffractive elements.

[0107] Hereinafter, a case where a liquid crystal element containing cholesteric liquid crystal is applied as the diffractive optical element OE will be described. Note that, although a case where a liquid crystal element is applied to the above-mentioned Configuration Example 1 will be described here, it goes without saying that a similar liquid crystal element can also be applied to the other Configuration Examples 2 to 12.

[0108] 20 is a diagram for explaining Application Example 1 of the liquid crystal element, in which the transparent substrate 20 is indicated by a dashed line.

[0109] The light-emitting unit LE includes a light-emitting element LE1, a light-emitting element LE2, and a light-emitting element LE3. The light-emitting element LE1, the light-emitting element LE2, and the light-emitting element LE3 are arranged at different positions without overlapping with each other, and are aligned in the second direction Y in the illustrated example. The light-emitting element LE1, the light-emitting element LE2, and the light-emitting element LE3 are configured to emit illumination light of different wavelength bands.

[0110] For example, the light-emitting element LE1 is configured to emit light in a first wavelength band including a blue component, the light-emitting element LE2 is configured to emit light in a second wavelength band including a green component, and the light-emitting element LE3 is configured to emit light in a third wavelength band including a red component.

[0111] In the diffractive optical element OE, the diffractive elements OE1, OE2, and OE3 are stacked.

[0112] The light emitting elements LE1, LE2, and LE3 overlap the diffractive elements OE1, OE2, and OE3, respectively, with the transparent substrate 20 sandwiched therebetween. In the illustrated example, the two light emitting units LE are aligned in the first direction X and overlap both end portions of the diffractive optical element OE.

[0113] Light in a first wavelength band emitted from the light-emitting element LE1 is diffracted by the diffraction element OE1 after passing through the transparent substrate 20. Light in a second wavelength band emitted from the light-emitting element LE2 is diffracted by the diffraction element OE2 after passing through the transparent substrate 20. Light in a third wavelength band emitted from the light-emitting element LE3 is diffracted by the diffraction element OE3 after passing through the transparent substrate 20.

[0114] FIG. 21 is a diagram illustrating a second application example of the liquid crystal element.

[0115] Application example 2 differs from application example 1 in that the light-emitting elements LE1, LE2, and LE3 are aligned in the first direction X.

[0116] In the diffractive optical element OE, the diffractive elements OE1, OE2, and OE3 are stacked.

[0117] The light emitting elements LE1, LE2, and LE3 overlap the diffractive elements OE1, OE2, and OE3, respectively, with the transparent substrate 20 sandwiched therebetween. In the illustrated example, the two light emitting units LE are aligned in the first direction X and overlap both end portions of the diffractive optical element OE.

[0118] FIG. 22 is a diagram illustrating a third application example of the liquid crystal element.

[0119] Application example 3 differs from application example 1 in that diffraction element OE1, diffraction element OE2, and diffraction element OE3 are arranged at different positions without overlapping with each other. In the illustrated example, diffraction element OE1, diffraction element OE2, and diffraction element OE3 are aligned in the second direction Y.

[0120] The light emitting elements LE1, LE2, and LE3 are aligned in the second direction Y. The light emitting element LE1 overlaps the diffraction element OE1, the light emitting element LE2 overlaps the diffraction element OE2, and the light emitting element LE3 overlaps the diffraction element OE3.

[0121] FIG. 23 is a diagram illustrating a fourth application example of the liquid crystal element.

[0122] In Application Example 4, the diffractive optical element OE includes a diffractive element OE1 and a diffractive element OE2. The diffractive elements OE1 and OE2 extend in a first direction X and are arranged at an interval in a second direction Y. Each of the diffractive elements OE1 and OE2 diffracts a wide wavelength band. For example, the diffractive element OE1 is configured to diffract illumination light in a wavelength band including a blue component and a green component, and the diffractive element OE2 is configured to diffract illumination light in a wavelength band including a green component and a red component.

[0123] The light-emitting unit LE includes light-emitting elements LE1, LE2, LE3, and LE4. For example, the light-emitting element LE1 is configured to emit light in a first wavelength band including a blue component. The light-emitting element LE2 is configured to emit light in a second wavelength band including a green component. The light-emitting element LE3 is configured to emit light in the second wavelength band including a green component. The light-emitting element LE4 is configured to emit light in a third wavelength band including a red component.

[0124] The light-emitting elements LE1 and LE2 are adjacent to each other and overlap the diffraction element OE1. The light-emitting elements LE3 and LE4 are adjacent to each other and overlap the diffraction element OE2. The light-emitting elements LE2 and LE3 are arranged in the second direction Y at an interval.

[0125] In the above Application Examples 1 to 4, for example, the light-emitting element LE1 corresponds to the first light-emitting element, and the light-emitting element LE2 or the light-emitting element LE3 corresponds to the second light-emitting element. Also, the diffraction element OE1 corresponds to the first diffraction element, the diffraction element OE2 corresponds to the second diffraction element, and the diffraction element OE3 corresponds to the third diffraction element.

[0126] Next, a specific cross-sectional structure of the display device 1 will be described. Here, a description will be given of Configuration Example 1. Note that various wirings, insulating layers, switching elements, etc. are omitted from the illustration.

[0127] FIG. 24 is a cross-sectional view showing an example of the configuration of the display device 1 taken along line CD shown in FIG.

[0128] The transparent substrate 10 and the transparent substrate 20 face each other in the third direction Z. The liquid crystal layer LC is located between the transparent substrate 10 and the transparent substrate 20 and is sealed with a seal SE. The pixel electrodes PE of each pixel PX are located between the transparent substrate 10 and the liquid crystal layer LC and are covered with an alignment film AL1. A common electrode CE facing the plurality of pixel electrodes PE is located between the transparent substrate 20 and the liquid crystal layer LC and is covered with an alignment film AL2. The liquid crystal layer LC is in contact with the alignment films AL1 and AL2.

[0129] The transparent substrate 10 and the transparent substrate 20 may be glass substrates or resin substrates. The pixel electrode PE and the common electrode CE are transparent electrodes made of a transparent conductive material such as indium tin oxide (ITO).

[0130] The light-emitting unit LE and the diffractive optical element OE face each other across the transparent substrate 20 in the third direction Z. The diffractive optical element OE faces an area of ​​the main surface 20A that does not overlap with the seal SE. The light-emitting unit LE faces an area of ​​the main surface 20B that does not overlap with the seal SE.

[0131] Although not described in detail, the light-emitting unit LE includes a red light-emitting unit, a green light-emitting unit, and a blue light-emitting unit as light-emitting elements. These red light-emitting unit, green light-emitting unit, and blue light-emitting unit may be turned on sequentially or all at the same time. As described above, the diffractive optical element OE includes a holographic optical element or a liquid crystal element including cholesteric liquid crystal.

[0132] In such a display device 1, when a voltage is applied to each pixel PX, illumination light emitted from the light-emitting unit LE is scattered by the liquid crystal layer LC of each pixel PX. When the liquid crystal layer LC is in a transparent state, when the display device 1 is observed from the main surface 10A side, the background can be observed through the display device 1. Similarly, when the display device 1 is observed from the main surface 20B side, the background can be observed through the display device 1.

[0133] FIG. 25 is a cross-sectional view showing another example of the configuration of the display device 1 taken along the line CD shown in FIG.

[0134] The configuration example shown in FIG. 25 differs from the configuration example shown in FIG. 24 in that the display device 1 further includes a transparent substrate 30. The transparent substrate 30 is located between the transparent substrates 10 and 20 in the third direction Z. A liquid crystal layer LC is located between the transparent substrates 10 and 30 and sealed with a seal SE. A common electrode CE facing the plurality of pixel electrodes PE is located between the transparent substrate 30 and the liquid crystal layer LC and is covered with an alignment film AL2. The transparent substrate 30 is adhered to the main surface 20A of the transparent substrate 20 via a transparent adhesive layer AD. The adhesive layer AD has a refractive index equivalent to that of the transparent substrates 20 and 30. Therefore, undesired interface reflection between the transparent substrates 20 and 30 is suppressed.

[0135] The light-emitting unit LE and the diffractive optical element OE face each other in the third direction Z, sandwiching the transparent substrate 20 therebetween. The diffractive optical element OE faces an area of ​​the main surface 20A that does not overlap with the transparent substrate 30. The light-emitting unit LE faces an area of ​​the main surface 20B that does not overlap with the transparent substrate 30.

[0136] In this configuration example, the transparent substrate 20 functions as a cover member and is thicker than the transparent substrates 10 and 30 that sandwich the liquid crystal layer LC. In each of the configuration examples shown in FIGS. 24 and 25, the diffractive optical element OE may be disposed on the main surface 10A of the transparent substrate 10. In addition, in the display device 1 shown in Figures 20 to 25, the light-emitting unit LE has a red light-emitting unit, a green light-emitting unit, and a blue light-emitting unit, and field sequential driving is used to display an image by sequentially lighting up these red light-emitting unit, green light-emitting unit, and blue light-emitting unit.

[0137] Next, some modified examples will be described.

[0138] FIG. 26 is a plan view showing the first modification.

[0139] The transparent substrate 20 is formed in a substantially semicircular shape in a plan view. In the illustrated example, the transparent substrate 20 has a linear edge portion 20L along the first direction X and an arc-shaped edge portion 20C. The light source unit LU is disposed along the edge portion 20L.

[0140] The diffractive optical element OE is disposed along the edge 20C in the vicinity of the light source unit LU. In one example, the diffractive optical element OE faces the main surface of the transparent substrate 20, as in Configuration Example 1, but may face the edge 20C of the transparent substrate 20.

[0141] The light emitting portion LE overlaps one end of the diffractive optical element OE. The light emitting portion LE may face the edge portion 20L or the edge portion 20C of the transparent substrate 20.

[0142] FIG. 27 is a plan view showing the second modification.

[0143] In Modification 2, the transparent substrate 20 is formed in a circular shape in a plan view. The diffractive optical element OE is formed in an annular shape and faces the main surface of the transparent substrate 20, as in Configuration Example 1, etc., but may face a circular edge portion 20C of the transparent substrate 20. The light-emitting portion LE overlaps the diffractive optical element OE, but may face the edge portion 20C. In the illustrated example, there is one light-emitting portion LE, but there may be multiple light-emitting portions LE.

[0144] FIG. 28 is a plan view showing the third modification.

[0145] Modification 3 differs from Modification 2 in that the diffractive optical element OE is formed in a U-shape. The diffractive optical element OE faces the main surface of the transparent substrate 20, but may face a circular edge portion 20C of the transparent substrate 20. The light-emitting unit LE overlaps the diffractive optical element OE, but may face the edge portion 20C.

[0146] FIG. 29 is a plan view showing the fourth modification.

[0147] Modification 4 differs from Modification 2 in that the transparent substrate 20 is formed in a circular ring shape in a plan view. That is, the transparent substrate 20 has a through-hole 20H in the center. The diffractive optical element OE is formed in a circular ring shape, but may also be formed in a U-shape as in Modification 3.

[0148] FIG. 30 is a plan view showing the fifth modification.

[0149] Modification 5 differs from Modification 2 in that the transparent substrate 20 has a cutout portion 20K. The diffractive optical element OE is disposed over almost the entire periphery of the transparent substrate 20, excluding the cutout portion 20K. The diffractive optical element OE faces the main surface of the transparent substrate 20, but may face an edge portion 20C of the transparent substrate 20. The light-emitting portion LE faces the side surface 20S of the transparent substrate 20 at the cutout portion 20K, but may face the edge portion 20C or the main surface of the transparent substrate 20.

[0150] According to such modifications 1 to 5, the light emitted from the light-emitting unit LE is diffracted by the diffraction surface DS of the diffractive optical element OE, and can illuminate almost the entire area of ​​the transparent substrate 20 regardless of the shape of the transparent substrate 20.

[0151] In the above-described embodiment, for example, the transparent substrate 10 corresponds to the first transparent substrate, the transparent substrate 20 corresponds to the second transparent substrate, and the transparent substrate 30 corresponds to the third transparent substrate.

[0152] In the above embodiment, the description has been given focusing on the configuration of the display device 1, but the combination of the transparent substrate 20, the light emitting unit LE, and the diffractive optical element OE can be configured as a light source device.

[0153] The light emitting unit LE shown in each example may include, in addition to the light emitting element, a light control element that controls the traveling direction of light emitted from the light emitting element.

[0154] As described above, according to this embodiment, it is possible to provide a display device and a light source device that can improve the uniformity of luminance.

[0155] All display devices and light source devices that can be implemented by a person skilled in the art by appropriately modifying the design based on the display device and light source device described above as embodiments of the present invention also fall within the scope of the present invention as long as they include the gist of the present invention.

[0156] Within the scope of the concept of the present invention, a person skilled in the art may conceive of various modifications, and these modifications are also understood to fall within the scope of the present invention. For example, even if a person skilled in the art appropriately adds or deletes components or modifies the design of the above-described embodiment, or adds or omits steps or modifies conditions, these modifications are also included within the scope of the present invention as long as they maintain the gist of the present invention.

[0157] Furthermore, with regard to other effects brought about by the aspects described in the above embodiments, those that are clear from the description in this specification or that can be appropriately thought of by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0158] 1...Display device 10...Transparent substrate 20...Transparent substrate 30...Transparent substrate LC...Liquid crystal layer DA: Display area PE: Pixel electrode CE: Common electrode OE: Diffractive optical element LE: Light emitting part LG: Light guide LU: Light source unit

Claims

1. a first transparent substrate; a second transparent substrate having a first surface and a second surface different from the first surface; a liquid crystal layer located between the first transparent substrate and the second transparent substrate and including a polymer dispersed liquid crystal; a light emitting unit configured to emit illumination light for illuminating the liquid crystal layer; a diffractive optical element disposed opposite the first surface and not overlapping with the liquid crystal layer, the diffractive optical element configured to diffract the illumination light; Equipped with Display device.

2. the first surface is a first main surface of the second transparent substrate facing the first transparent substrate, the second surface is a second main surface of the second transparent substrate opposite to the first main surface, The light emitting portion faces the second surface. The display device according to claim 1 .

3. The diffractive optical element is formed in a strip shape, the light emitting portion overlaps one end of the diffractive optical element; The display device according to claim 2 .

4. The diffractive optical element is formed in a strip shape, the light emitting portion overlaps both end portions of the diffractive optical element; The display device according to claim 2 .

5. the first surface is a first main surface of the second transparent substrate facing the first transparent substrate, the second surface is a side surface of the second transparent substrate that intersects with the first main surface, The light emitting portion faces the second surface. The display device according to claim 1 .

6. The diffractive optical element is formed in a strip shape, the light emitting portion is located on one end side of the diffractive optical element; The display device according to claim 5 .

7. The diffractive optical element is formed in a strip shape, the light emitting portion is located on one end side and the other end side of the diffractive optical element; The display device according to claim 5 .

8. In the diffractive optical element, the thickness of one end is smaller than the thickness of the other end. The display device according to claim 3 or 6.

9. In the diffractive optical element, the width of one end is smaller than the width of the other end. The display device according to claim 3 or 6.

10. Further, a light guide is provided, the light guide is located between the second transparent substrate and the diffractive optical element; The light emitting portion faces the light guide. The display device according to claim 1 .

11. the light guide has a first side surface facing a side surface of the second transparent substrate and a second side surface intersecting the first side surface, The light emitting portion faces one end of the second side surface of the light guide. The display device according to claim 10.

12. the light guide has a first side surface facing a side surface of the second transparent substrate and a second side surface intersecting the first side surface, The light emitting portion faces both end portions of the second side surface of the light guide body. The display device according to claim 10.

13. the light guide includes a first side surface facing a side surface of the second transparent substrate and a first end surface intersecting the first side surface, the light emitting portion faces the first end surface of the light guide body; The display device according to claim 10.

14. the light guide includes a first side surface facing a side surface of the second transparent substrate, a first end surface intersecting the first side surface, and a second end surface opposite to the first end surface; the light emitting portion faces the first end surface and the second end surface of the light guide body; The display device according to claim 10.

15. The light emitting unit a first light-emitting element configured to emit light in a first wavelength band; a second light-emitting element configured to emit light in a second wavelength band different from the first wavelength band, The diffractive optical element is a first diffraction element configured to diffract the illumination light in the first wavelength band; a second diffraction element configured to diffract the illumination light in the second wavelength band; The display device according to claim 1 .

16. the first diffraction element and the second diffraction element are stacked, the first light-emitting element and the second light-emitting element overlap with the first diffraction element and the second diffraction element, respectively; The display device according to claim 15.

17. the first diffraction element is disposed at a position different from that of the second diffraction element, the first light-emitting element overlaps the first diffraction element, The second light-emitting element is overlapped with the second diffraction element. The display device according to claim 15.

18. the diffractive optical element comprises a holographic optical element or a liquid crystal element including a cholesteric liquid crystal; The display device according to claim 1 .

19. a seal for sealing the liquid crystal layer between the first transparent substrate and the second transparent substrate; the diffractive optical element faces a region of the first surface that does not overlap with the seal; The display device according to claim 1 .

20. a pixel electrode located between the first transparent substrate and the liquid crystal layer; a common electrode located between the second transparent substrate and the liquid crystal layer; 20. The display device according to claim 19.

21. further comprising a third transparent substrate located between the first transparent substrate and the second transparent substrate; the liquid crystal layer is sealed between the first transparent substrate and the third transparent substrate; the third transparent substrate is bonded to the first main surface of the second transparent substrate; the diffractive optical element faces a region of the first main surface that does not overlap with the third transparent substrate; The display device according to claim 1 .

22. a pixel electrode located between the first transparent substrate and the liquid crystal layer; a common electrode located between the third transparent substrate and the liquid crystal layer; The display device according to claim 21.

23. a transparent substrate having a first surface and a second surface different from the first surface; a light emitting unit configured to emit illumination light for illuminating the transparent substrate; a diffractive optical element facing the first surface and configured to diffract the illumination light; Equipped with Light source device.

24. the first surface is a first main surface of the transparent substrate, the second surface is a second main surface of the transparent substrate opposite to the first main surface, The light emitting portion faces the second surface.

24. The light source device according to claim 23.

25. the first surface is a first main surface of the transparent substrate, the second surface is a side surface of the transparent substrate that intersects with the first main surface, The light emitting portion faces the second surface.

24. The light source device according to claim 23.

26. Further, a light guide is provided, the first surface is a side surface of the transparent substrate, the light guide is located between the transparent substrate and the diffractive optical element; The light emitting portion faces the light guide.

24. The light source device according to claim 23.

Images