Display device

Abstract

To provide a display device whose size can be reduced.SOLUTION: In one embodiment, a display device includes a display element including a display unit that displays images, a first retardation plate overlapping with the display element, a holographic optical element disposed adjacent to the display element without overlapping with the display element, a second retardation plate having a first surface that faces the first retardation plate and the holographic optical element through an air layer and a second surface on the opposite side of the first surface, and a reflective polarizing plate disposed on the second surface.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present embodiment relates to a display device. [Background technology]

[0002] In recent years, technology that provides, for example, virtual reality (VR) using a head-mounted display worn on the user's head has been attracting attention. The head-mounted display is configured to display images on a display provided in front of the user's eyes. This allows a user wearing the head-mounted display to experience a realistic virtual reality space. As an example of a technology for realizing such a head mounted display, a technology is known in which a holographic optical element is used to guide light from a display element to the user's pupil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-148655 A [Patent Document 2] JP 2010-33026 A [Patent Document 3] JP 2009-157026 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the embodiment is to provide a display device that can be made compact. [Means for solving the problem]

[0005] According to one embodiment, the display device comprises: The optical element includes a display element having a display unit for displaying an image, a first retardation plate overlapping the display element, a holographic optical element adjacent to the display element without overlapping the display element, a second retardation plate having a first surface facing the first retardation plate and the holographic optical element via an air layer and a second surface opposite the first surface, and a reflective polarizing plate disposed on the second surface.

[0006] According to one embodiment, the display device comprises: The display device comprises a display element having a display portion for displaying an image, a holographic optical element adjacent to the display element without overlapping the display element, a transparent substrate having a first main surface facing the display element and the holographic optical element and a second main surface opposite the first main surface, and a transparent adhesive layer for adhering the display element and the holographic optical element to the first main surface, respectively. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing an example of the appearance of glasses 1 to which the display device DSP of this embodiment is applied. [Diagram 2] FIG. 2 is a diagram showing an example of the configuration of the display device DSP shown in FIG. [Diagram 3] FIG. 3 is a diagram showing an example of the configuration of a display element DE applicable to the display device DSP shown in FIG. [Figure 4] FIG. 4 is a diagram for explaining the optical action of the display device DSP shown in FIG. [Diagram 5] FIG. 5 is a diagram showing another example of the configuration of the display device DSP shown in FIG. [Figure 6] FIG. 6 is a diagram showing another example of the configuration of the display device DSP shown in FIG. [Figure 7] FIG. 7 is a diagram showing another example of the configuration of the display device DSP shown in FIG. [Figure 8] FIG. 8 is a diagram showing another example of the configuration of the display device DSP shown in FIG. [Figure 9]FIG. 9 is a diagram showing another example of the configuration of the display device DSP shown in FIG. [Figure 10] FIG. 10 is a diagram showing another example of the configuration of the display device DSP shown in FIG. [Figure 11] FIG. 11 is a diagram showing an example of the configuration of a display element DE applicable to the display device DSP shown in FIG. [Figure 12] FIG. 12 is a diagram for explaining the optical action of the display device DSP shown in FIG. [Figure 13] FIG. 13 is a diagram showing another example of the configuration of the display device DSP shown in FIG. [Figure 14] FIG. 14 is a diagram showing another example of the configuration of the display device DSP shown in FIG. [Figure 15] FIG. 15 is a diagram for explaining an example of a method for manufacturing the holographic optical element HE. [Figure 16] FIG. 16 is a diagram for explaining another example of the method for producing the holographic optical element HE. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the present embodiment will be described with reference to the drawings. Note that the disclosure is merely an example, and those who are skilled in the art can easily conceive of appropriate modifications while maintaining the gist of the invention are naturally included in the scope of the present invention. In addition, the drawings may be schematic in terms of width, thickness, shape, etc. of each part compared to the actual embodiment in order to make the explanation clearer, but they are merely examples and do not limit the interpretation of the present invention. In addition, in this specification and each figure, components that perform the same or similar functions as those described above with respect to the previous figures are given the same reference numerals, and duplicate detailed explanations may be omitted as appropriate.

[0009] In addition, in the drawings, an X-axis, a Y-axis, and a Z-axis that are perpendicular to each other are shown as necessary to facilitate understanding. The direction along the X-axis is called the first direction X, the direction along the Y-axis is called the second direction Y, and the direction along the Z-axis is called the third direction Z. The X-axis, the Y-axis, and the Z-axis may intersect at an angle other than 90°. The plane defined by the X-axis and the Y-axis is called the XY plane, and viewing the XY plane is called planar view.

[0010] FIG. 1 is a perspective view showing an example of the appearance of glasses 1 to which the display device DSP of this embodiment is applied. The glasses 1 include, for example, a display device DSPR for the right eye and a display device DSPL for the left eye. Each of the display devices DSPR and DSPL includes a display element DE and a holographic optical element HE. The display element DE and the holographic optical element HE are aligned in a first direction X. The display devices DSPR and DSPL are aligned in a second direction Y. Note that the display element DE and the holographic optical element HE may be aligned in the second direction Y, or may be aligned in a direction different from the first direction X and the second direction Y.

[0011] The display devices DSPR and DSPL have substantially the same configuration, and will hereinafter be described simply as the display device DSP.

[0012] FIG. 2 is a diagram showing an example of the configuration of the display device DSP shown in FIG.

[0013] The display device DSP includes a display element DE, a first retardation plate R1, a holographic optical element HE, a second retardation plate R2, and a reflective polarizer RP. The display element DE, the first retardation plate R1, the holographic optical element HE, the second retardation plate R2, and the reflective polarizer RP are all formed in a flat plate shape along the XY plane. A normal Nhe of the holographic optical element HE, a normal Nrp of the reflective polarizer RP, and a normal Nde of the display element DE are parallel to each other and to the third direction Z.

[0014] The display element DE includes an illumination device IL, a liquid crystal panel PNL, a first polarizing plate P1, and a second polarizing plate P2. The first polarizing plate P1 is disposed between the illumination device IL and the liquid crystal panel PNL in the third direction Z. The liquid crystal panel PNL is disposed between the first polarizing plate P1 and the second polarizing plate P2 in the third direction Z. The transmission axis T1 of the first polarizing plate P1 and the transmission axis T2 of the second polarizing plate P2 are orthogonal to each other. In one example, the transmission axis T1 is parallel to the first direction X, and the transmission axis T2 is parallel to the second direction Y. Such a display element DE is configured to emit linearly polarized display light DL from the second polarizing plate PL2. The polarization axis of the display light DL when emitted from the second polarizing plate PL2 is parallel to the transmission axis T2. The display light DL when emitted from the second polarizing plate PL2 is, for example, divergent light.

[0015] The configuration of the display element DE is not limited to the illustrated example. For example, the display element DE may be a display panel equipped with a self-luminous light-emitting element such as an organic electroluminescence (EL) element, a micro LED, or a mini LED. When the display element DE is a display panel equipped with a light-emitting element, the illumination device and the first polarizing plate are omitted.

[0016] The first retardation plate R1 overlaps the display element DE in the third direction Z. In the illustrated example, the first retardation plate R1 overlaps the second polarizing plate P2. Such a first retardation plate R1 is a quarter-wave plate, and imparts a phase difference of a quarter wavelength to light of a predetermined wavelength that is transmitted through it. Although not described in detail, the slow axis of the first retardation plate R1 intersects with the transmission axis T1 of the first polarizing plate P1 at an angle of about 45°. In this specification, the state in which two members "overlap" is defined as a state in which part of one member exists on the normal line of the other member. The "overlapping" state includes a state in which two members are in contact with each other, a state in which two members are bonded to each other, and a state in which there is a space or another member between the two members.

[0017] The holographic optical element HE is disposed adjacent to the display element DE in the first direction X without overlapping with the display element DE in the third direction Z. The holographic optical element HE is supported by a support BS1. The holographic optical element HE is a resin film on which an interference fringe pattern is recorded, and has a lens effect of diffracting incident light of a specific wavelength in a predetermined direction and focusing the incident light.

[0018] The second retardation plate R2 is disposed so as to face the first retardation plate R1 and the holographic optical element HE in the third direction Z via an air layer A. The second retardation plate R2 has a first surface R2a and a second surface R2b opposite to the first surface R2a. The first surface R2a and the second surface R2b face each other in the third direction Z. The first surface R2a corresponds to a surface facing the first retardation plate R1 and the holographic optical element HE. Such a second retardation plate R2 is a quarter-wave plate, and imparts a phase difference of a quarter wavelength to light of a predetermined wavelength that is transmitted through the second retardation plate R2. Although not described in detail, the slow axis of the second retardation plate R2 intersects with the transmission axis T2 of the second polarizing plate P2 at an angle of about 45° and is perpendicular to the slow axis of the first retardation plate R1.

[0019] The reflective polarizer RP is disposed on the second surface R2b of the second retardation plate R2. In the illustrated example, the laminate of the reflective polarizer RP and the second retardation plate R2 is supported by a transparent support BS2. As the reflective polarizer RP, a multilayer thin film type, a wire grid type, or the like can be applied. Such a reflective polarizer RP is configured to reflect a first linearly polarized light and transmit a second linearly polarized light different from the first linearly polarized light. The transmission axis Trp of the reflective polarizer RP and the transmission axis T2 of the second polarizer P2 are mutually orthogonal. In one example, the transmission axis Trp is parallel to the first direction X, the polarization axis of the first linearly polarized light is orthogonal to the transmission axis Trp, and the polarization axis of the second linearly polarized light is parallel to the transmission axis Trp.

[0020] The optical function in the display device DSP will be briefly explained below. As indicated by the dashed line, the display light DL emitted from the display element DE passes through the first retardation plate R1, then passes through the air layer A, passes through the second retardation plate R2, and is reflected by the reflective polarizing plate RP. The display light DL reflected by the reflective polarizing plate RP passes through the air layer A and is reflected by the holographic optical element HE. The display light DL reflected by the holographic optical element HE passes through the air layer A again, passes through the second retardation plate R2, then passes through the reflective polarizing plate RP, and is focused on the user's pupil E due to the lens action of the holographic optical element HE.

[0021] FIG. 3 is a diagram showing an example of the configuration of a display element DE applicable to the display device DSP shown in FIG.

[0022] The liquid crystal panel PNL is of a transmissive type and includes a first substrate SUB1, a second substrate SUB2, and a liquid crystal layer LC. The liquid crystal layer LC is held between the first substrate SUB1 and the second substrate SUB2 in the third direction Z, and is sealed by a seal SE. The liquid crystal panel PNL is disposed between the illumination device IL and the first retardation plate R1 in the third direction Z. The first polarizing plate P1 is disposed between the illumination device IL and the liquid crystal panel PNL in the third direction Z, and is bonded to, for example, the first substrate SUB1. The second polarizing plate P2 is disposed between the liquid crystal panel PNL and the first retardation plate R1 in the third direction Z, and is bonded to, for example, the second substrate SUB2. The display section DA is a region of the liquid crystal panel PNL that is configured to display an image. The normal Nde of the display element DE corresponds to, for example, the normal of the first substrate SUB1 or the second substrate SUB2.

[0023] The illumination device IL includes a light guide plate LG and a light source LS. The light guide plate LG faces the first polarizing plate P1 in the third direction Z. The light source LS faces a side surface LGa of the light guide plate LG in the first direction X. The light source LS is disposed on the opposite side of the light guide plate LG to the holographic optical element HE in the first direction X. The liquid crystal panel PNL is located between the light source LS and the holographic optical element HE in the first direction X.

[0024] Although not described in detail, the light source LS includes a light emitting element configured to emit light of a blue wavelength, a light emitting element configured to emit light of a green wavelength, and a light emitting element configured to emit light of a red wavelength. As these light emitting elements, for example, laser elements are applied.

[0025] The light emitted from the light source LS is propagated while being totally reflected inside the light guide plate LG. Among the propagated light, the light not meeting the total reflection condition is emitted from the light guide plate LG toward the liquid crystal panel PNL to form the illumination light. The illumination light incident on the liquid crystal panel PNL is inclined with respect to the normal line Nde. The liquid crystal panel PNL selectively modulates the illumination light in the display section DA. Then, a part of the illumination light is transmitted through the second polarizer P2 to form the linearly polarized display light DL.

[0026] FIG. 4 is a diagram for explaining the optical action of the display device DSP shown in FIG.

[0027] First, the display light DL of the first linearly polarized light LP1 transmitted through the second polarizer P2 of the display element DE is converted into the first circularly polarized light CP1 by transmitting through the first retardation plate R1. The first circularly polarized light CP1 transmitted through the first retardation plate R1 is converted into the first linearly polarized light LP1 by transmitting through the second retardation plate R2.

[0028] The first linearly polarized light LP1 that has passed through the second retardation plate R2 is reflected by the reflective polarizing plate RP. The first linearly polarized light LP1 that has been reflected by the reflective polarizing plate RP passes through the second retardation plate R2 and is converted into the second circularly polarized light CP2. The second circularly polarized light CP2 is circularly polarized in the opposite direction to the first circularly polarized light CP1.

[0029] The second circularly polarized light CP2 transmitted through the second phase difference plate R2 is reflected and diffracted by the holographic optical element HE. The second circularly polarized light CP2 reflected by the holographic optical element HE is transmitted through the second phase difference plate R2 and converted into the second linearly polarized light LP2. The second linearly polarized light LP2 is linearly polarized light having a polarization axis perpendicular to the first linearly polarized light LP1.

[0030] The second linearly polarized light LP2 transmitted through the second phase difference plate R2 is transmitted through the reflective polarizing plate RP and is focused on the pupil E of the user due to the lens action of the holographic optical element HE.

[0031] The first linearly polarized light LP1 described with reference to FIG. 4 may be replaced with the second linearly polarized light LP2, and the first circularly polarized light CP1 may be replaced with the second circularly polarized light CP2.

[0032] According to this configuration example, the thickness along the third direction Z can be made thinner and the weight can be reduced, compared to an optical system including optical components made of glass, resin, etc. Therefore, the display device DSP can be made smaller.

[0033] Furthermore, the display element DE and the holographic optical element HE are aligned in the first direction X without overlapping in the third direction Z. That is, there is no holographic optical element HE between the display element DE and the reflective polarizer RP in the third direction Z. For this reason, the display light DL is not reflected by the holographic optical element HE in the optical path of the display light DL from the display element DE to the reflective polarizer RP. Therefore, assuming that almost all of the reflected light from the reflective polarizer RP is reflected by the holographic optical element HE, almost 100% of the display light DL emitted from the display element DE can be focused on the pupil E, improving the light utilization efficiency.

[0034] FIG. 5 is a diagram showing another example of the configuration of the display device DSP shown in FIG. The configuration example shown in Fig. 5 differs from the configuration example shown in Fig. 2 in that a light shielding body LSM is arranged on the back side of the holographic optical element HE. In the illustrated example, the light shielding body LSM overlaps the support body BS1 in the third direction Z. The holographic optical element HE is located between the second retardation plate R2 and the light shielding body LSM in the third direction Z. The light shielding body LSM may be a film adhered to the support body BS1, or may be a plate material that can be attached to and detached from the glasses. The light shielding body LSM may also be a liquid crystal element or the like that is configured to be able to change the transmittance of external light. Glasses equipped with a display device DSP having such an example configuration can be used, for example, to provide virtual reality.

[0035] FIG. 6 is a diagram showing another example of the configuration of the display device DSP shown in FIG. The configuration example shown in Fig. 6 differs from the configuration example shown in Fig. 2 in that the holographic optical element HE is configured to transmit external light AL. A user can view the image displayed on the display element DE while viewing the surrounding environment of the display device DSP. Glasses equipped with a display device DSP having such a configuration example can be used, for example, to provide augmented reality.

[0036] FIG. 7 is a diagram showing another example of the configuration of the display device DSP shown in FIG. The configuration example shown in FIG. 7 differs from the configuration example shown in FIG. 2 in that the first retardation plate R1, the second retardation plate R2, and the holographic optical element HE are each covered with an antireflection layer AR. If the anti-reflection layer AR were not present, undesired reflected light would be generated at the interface between the first retardation plate R1 and the air layer, the interface between the second retardation plate R2 and the air layer, and the interface between the holographic optical element HE and the air layer. Such undesired reflected light would reach the user's pupil E via an optical path different from the normal optical path of the display light DL, which could cause a deterioration in display quality. 7, reflections at the interface between the first retardation plate R1 and the air layer, reflections at the interface between the second retardation plate R2 and the air layer, and reflections at the interface between the holographic optical element HE and the air layer are suppressed, thereby making it possible to suppress deterioration of display quality.

[0037] FIG. 8 is a diagram showing another example of the configuration of the display device DSP shown in FIG. The configuration example shown in Fig. 8 differs from the configuration example shown in Fig. 2 in that the display light DL is parallel light. In this configuration example, in the first direction in which the display element DE and the holographic optical element HE are aligned, the width Wda of the display unit DA is equal to the width Whe of the holographic optical element HE. When the display light DL is a diverging light, the width Whe needs to be set larger than the width Wda. In the configuration example shown in Fig. 8, the width Whe of the holographic optical element HE can be made smaller than that in the configuration example shown in Fig. 2, and the display device DSP can be further miniaturized. In addition, since the emission angle of the display light DL is constant, the optical design is easy. Although not shown, an anti-reflection layer AR may be applied in the same manner as in the configuration example shown in FIG.

[0038] FIG. 9 is a diagram showing another example of the configuration of the display device DSP shown in FIG. The configuration example shown in Fig. 9 differs from the configuration example shown in Fig. 2 in that the normal Nde of the display element DE is inclined with respect to the normal Nrp of the reflective polarizer RP. The display element DE has an end DEa close to the holographic optical element HE and an end DEb opposite to the end DEa. The display element DE is inclined so that the end DEb is closer to the reflective polarizer RP than the end DEa. The normal Nhe of the holographic optical element HE is parallel to the normal Nrp. The display light DL emitted along the normal line Nde of the display element DE may be divergent light or parallel light. The display element DE is configured to display an image in consideration of distortion so that a normal image is focused on the pupil E. According to this configuration example, the width along the first direction X can be reduced, and the display device DSP can be further miniaturized. In addition, compared to the configuration example shown in Fig. 2 etc., the inclination of the emission angle of the display light DL is small, making the optical design easier and allowing the application of an existing illumination device IL for emitting the display light in the front direction. Although not shown, an anti-reflection layer AR may be applied in the same manner as in the configuration example shown in FIG.

[0039] FIG. 10 is a diagram showing another example of the configuration of the display device DSP shown in FIG.

[0040] The display device DSP includes a display element DE, a holographic optical element HE, a transparent substrate SB, and a transparent adhesive layer AD. The display element DE, the holographic optical element HE, and the transparent substrate SB are all formed in a flat plate shape along the XY plane.

[0041] The display element DE includes an illumination device IL, a liquid crystal panel PNL, a first polarizer P1, and a second polarizer P2, similar to the configuration example shown in Fig. 2. When the display element DE is a display panel including light-emitting elements, the illumination device and the first polarizer are omitted.

[0042] The holographic optical element HE is disposed adjacent to the display element DE in the first direction X without overlapping with the display element DE in the third direction Z. The holographic optical element HE is supported by a support BS1. The holographic optical element HE diffracts incident light of a specific wavelength in a predetermined direction and has a lens effect of focusing the incident light.

[0043] The transparent substrate SB is disposed so as to face the display element DE and the holographic optical element HE in the third direction Z. The liquid crystal panel PNL is disposed between the illumination device IL and the transparent substrate SB in the third direction Z. The transparent substrate SB has a first main surface SBa and a second main surface SBb opposite to the first main surface SBa. The first main surface SBa and the second main surface SBb face each other in the third direction Z. The first main surface SBa corresponds to a surface facing the display element DE and the holographic optical element HE. The second main surface SBb is in contact with a low refractive index layer having a refractive index lower than that of the transparent substrate SB. In the illustrated example, the low refractive index layer is air. Such a transparent substrate SB is a glass substrate or a resin substrate.

[0044] The transparent adhesive layer AD bonds the display element DE and the holographic optical element HE to the first main surface SBa, respectively. The refractive index of the transparent adhesive layer AD is desirably the same as that of the transparent substrate SB in order to prevent the generation of undesirable reflective interfaces.

[0045] The optical function in the display device DSP will be briefly explained below. The display light DL emitted from the display element DE is incident on the transparent substrate SB after passing through the transparent adhesive layer AD, as indicated by the dashed line. The display light DL incident on the transparent substrate SB is totally reflected at the second main surface SBb. In other words, the display element DE is configured to emit the display light DL at an angle at which the display light DL is totally reflected at the second main surface SBb. The display light DL reflected by the transparent substrate SB is reflected by the holographic optical element HE after passing through the transparent adhesive layer AD. The display light DL reflected by the holographic optical element HE passes through the transparent adhesive layer AD again, passes through the transparent substrate SB, and is focused on the user's pupil E by the lens action of the holographic optical element HE.

[0046] FIG. 11 is a diagram showing an example of the configuration of a display element DE applicable to the display device DSP shown in FIG.

[0047] The display element DE includes a liquid crystal panel PNL, an illumination device IL, and a prism sheet PS. The prism sheet PS is disposed between the liquid crystal panel PNL and the illumination device IL in the third direction Z.

[0048] The liquid crystal panel PNL, like the configuration example shown in FIG. 3, is of a transmissive type, and includes a first substrate SUB1, a second substrate SUB2, and a liquid crystal layer LC.

[0049] The illumination device IL includes a light guide plate LG and a light source LS. The light guide plate LG faces the prism sheet PS in the third direction Z. The light source LS faces a side surface LGa of the light guide plate LG in the first direction X. The light source LS is disposed on the opposite side of the light guide plate LG to the holographic optical element HE in the first direction X. The liquid crystal panel PNL is located between the light source LS and the holographic optical element HE in the first direction X.

[0050] The light emitted from the light source LS is propagated while being totally reflected inside the light guide plate LG. Among the propagated light, the light not meeting the total reflection condition is emitted from the light guide plate LG toward the liquid crystal panel PNL to form the illumination light. When the illumination light passes through the prism sheet PS, it is refracted at an angle such that it is totally reflected by the second main surface SBb as described above. The illumination light that passes through the prism sheet PS is incident on the liquid crystal panel PNL. The liquid crystal panel PNL selectively modulates the illumination light in the display section DA. Then, a part of the illumination light passes through the second polarizing plate P2 to form the linearly polarized display light DL.

[0051] FIG. 12 is a diagram for explaining the optical action of the display device DSP shown in FIG.

[0052] First, the display light DL of the first linearly polarized light LP1 transmitted through the second polarizer P2 of the display element DE is incident on the transparent substrate SB and is totally reflected by the second main surface SBb. The display light DL totally reflected by the second main surface SBb is reflected and diffracted by the holographic optical element HE. The display light DL reflected by the holographic optical element HE is transmitted through the transparent substrate SB and is focused on the user's pupil E by the lens action of the holographic optical element HE.

[0053] 12 may be replaced with the second linearly polarized light LP2. Furthermore, the polarization state of the display light DL after passing through the second polarizer P2 does not need to be maintained as linearly polarized light.

[0054] According to this configuration example, the same effects as those of the configuration example shown in FIG. 2 can be obtained. Furthermore, optical components such as a retardation plate or a reflective polarizing plate are not required, which allows weight reduction and cost reduction to be achieved. Moreover, compared to the configuration example shown in FIG. 2, the thickness along the third direction Z can be further reduced. Furthermore, since there is no interface between the display element DE and an air layer, and no interface between the holographic optical element HE and an air layer, undesirable reflection on the optical path of the display light DL can be suppressed.

[0055] FIG. 13 is a diagram showing another example of the configuration of the display device DSP shown in FIG. The configuration example shown in FIG. 13 differs from the configuration example shown in FIG. 10 in that a light blocking body LSM is disposed on the back side of the holographic optical element HE. The configuration of the light blocking body LSM is similar to the configuration example described with reference to FIG. Glasses equipped with a display device DSP having such an example configuration can be used, for example, to provide virtual reality.

[0056] FIG. 14 is a diagram showing another example of the configuration of the display device DSP shown in FIG. The configuration example shown in Fig. 14 differs from the configuration example shown in Fig. 10 in that the holographic optical element HE is configured to transmit external light AL. A user can view the image displayed on the display element DE while viewing the surrounding environment of the display device DSP. Glasses equipped with a display device DSP having such a configuration example can be used, for example, to provide augmented reality.

[0057] A method for producing the holographic optical element HE will be briefly described below.

[0058] FIG. 15 is a diagram for explaining an example of a method for manufacturing the holographic optical element HE.

[0059] The photosensitive resin PP is formed on one surface of a transparent support BS. The support BS here may be the same as the support BS1 shown in FIG. 2 or may be a separate body from the support BS1.

[0060] The object light Ob is a parallel light, and is irradiated toward the photosensitive resin PP via the lens L1. At this time, the object light Ob is irradiated from a direction along the normal line Nbs of the support BS. The reference light Rf is a parallel light, and is irradiated toward the photosensitive resin PP via the lens L2. At this time, the reference light Rf is irradiated from a direction tilted with respect to the normal Nbs of the support BS. The reference light Rf and the object light Ob are lights of the same wavelength, and interfere with each other at the position of the photosensitive resin PP. In the photosensitive resin PP, interference fringes of the reference light Rf and the object light Ob are recorded. This produces a holographic optical element HE that has a lens effect equivalent to that of a concave mirror for incident light (divergent light) from a direction inclined to the normal Nbs. The holographic optical element HE produced in this way can be used, for example, as the holographic optical element HE of the display device DSP shown in FIG. 2 etc.

[0061] FIG. 16 is a diagram for explaining another example of the method for producing the holographic optical element HE.

[0062] The manufacturing method shown in Fig. 16 differs from the manufacturing method shown in Fig. 15 in that the reference light Rf is a parallel light and is irradiated toward the photosensitive resin PP without passing through a lens. The reference light Rf and the object light Ob are light of the same wavelength and interfere with each other at the position of the photosensitive resin PP. In the photosensitive resin PP, interference fringes of the reference light Rf and the object light Ob are recorded. This produces a holographic optical element HE that has a lens effect equivalent to that of a concave mirror for incident light (parallel light) from a direction inclined to the normal Nbs. The holographic optical element HE produced in this way can be used, for example, as the holographic optical element HE of the display device DSP shown in FIG. 8.

[0063] As described above, according to this embodiment, it is possible to provide a display device that can be made compact.

[0064] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0065] DSP…display device DE: Display element PNL: Liquid crystal panel IL: Lighting device R1…First retardation plate R2…Second retardation plate RP…Reflection type polarizing plate HE...Holographic Optical Element SB…Transparent substrate AD…Transparent adhesive layer LSM: Light shielding body

Claims

1. A display element including a display unit for displaying an image; a first retardation plate overlapping the display element; a holographic optical element adjacent to the display element without overlapping the display element; a second retardation plate having a first surface facing the first retardation plate and the holographic optical element via an air layer, and a second surface opposite to the first surface; A reflective polarizing plate disposed on the second surface; A display device comprising:

2. the display element is configured to emit linearly polarized display light, the first retardation plate and the second retardation plate are quarter-wave plates, The display device according to claim 1 , wherein the reflective polarizing plate is configured to reflect a first linearly polarized light and transmit a second linearly polarized light different from the first linearly polarized light.

3. The display device according to claim 1 , wherein the holographic optical element has a lens effect and is configured to reflect the light reflected by the reflective polarizing plate toward the reflective polarizing plate.

4. The display device according to claim 3 , further comprising a light blocking body disposed on a rear side of the holographic optical element.

5. The display device according to claim 3 , wherein the holographic optical element is configured to transmit external light.

6. 2. The display device according to claim 1, wherein the display element comprises: an illumination device; a liquid crystal panel arranged between the illumination device and the first retardation film; a first polarizing plate arranged between the illumination device and the liquid crystal panel; and a second polarizing plate arranged between the liquid crystal panel and the first retardation film.

7. The lighting device includes a light guide plate and a light source facing a side surface of the light guide plate, The display device according to claim 6 , wherein the liquid crystal panel is located between the light source and the holographic optical element in a direction in which the display element and the holographic optical element are aligned.

8. The display device of claim 1 , wherein the first retarder, the second retarder, and the holographic optical element are each covered with an anti-reflection layer.

9. The display device according to claim 1 , wherein the width of the display portion in a direction in which the display element and the holographic optical element are aligned is equal to the width of the holographic optical element.

10. a normal to the holographic optical element is parallel to a normal to the reflective polarizer; The display device according to claim 1 , wherein a normal to the display element is inclined with respect to a normal to the reflective polarizing plate.

11. A display element including a display unit for displaying an image; a holographic optical element adjacent to the display element without overlapping the display element; a transparent substrate having a first major surface facing the display element and the holographic optical element and a second major surface opposite the first major surface; a transparent adhesive layer that adheres the display element and the holographic optical element to the first main surface, respectively; A display device comprising:

12. The display device according to claim 11 , wherein the display element is configured to emit display light that is totally reflected by the second main surface.

13. The display device according to claim 11 , wherein the holographic optical element has a lens effect and is configured to reflect the light reflected by the second main surface toward the transparent substrate.

14. The display device according to claim 13 , further comprising a light blocking body disposed on a rear side of the holographic optical element.

15. The display device of claim 13 , wherein the holographic optical element is configured to transmit external light.

16. The display device according to claim 11 , wherein the display element comprises an illumination device, a liquid crystal panel disposed between the illumination device and the transparent substrate, and a prism sheet disposed between the illumination device and the liquid crystal panel.

17. The lighting device includes a light guide plate and a light source facing a side surface of the light guide plate, The display device according to claim 16 , wherein the liquid crystal panel is located between the light source and the holographic optical element in a direction in which the display element and the holographic optical element are aligned.

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