Display device

Abstract

To provide a display device in which the decrease in display quality can be suppressed.SOLUTION: In one embodiment, a display device includes a display element configured to emit display light of linearly polarized light, a first retardation plate overlapping with the display element, an optical element overlapping with the display element and the first retardation plate and having a lens action, a second retardation plate overlapping with the optical element, and a reflective polarizing plate overlapping with the second retardation plate through an air layer and capable of rotation relative to the second retardation plate.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. In such display devices, there is a demand for reducing stray light caused by undesired reflected light in order to improve the display quality. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-148655 A [Patent Document 2] JP 2013-167779 A [Patent Document 3] JP 2009-54305 A [Patent Document 4] Japanese Patent Application Publication No. 9-105928 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the embodiment is to provide a display device capable of suppressing degradation of display quality. [Means for solving the problem]

[0005] According to one embodiment, the display device comprises: The liquid crystal display device includes a display element configured to emit linearly polarized display light, a first retardation plate overlapping the display element, an optical element overlapping the display element and the first retardation plate and having a lens function, a second retardation plate overlapping the optical element, and a reflective polarizing plate overlapping the second retardation plate via an air layer and capable of rotating relatively to the second retardation plate. [Brief description of the drawings]

[0006] [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 for explaining the first shaft angle θ1 and the second shaft angle θ2. [Figure 6] FIG. 6 is a diagram showing an example of the configuration of the adjustment mechanism 3 that adjusts the rotation angle of the second transparent support BS2. [Figure 7] FIG. 7 is a diagram showing another example of the configuration of the adjustment mechanism 3 that adjusts the rotation angle of the second transparent support BS2. [Figure 8] FIG. 8 is a diagram for explaining reflected light at an interface included in the display device DSP shown in FIG. [Figure 9] FIG. 9 is a diagram for explaining reflected light at an interface included in a display device DSP as a comparative example. [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 another example of the configuration of the display device DSP shown in FIG. [Figure 12] FIG. 12 is a diagram showing the simulation results. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] 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 duplicated detailed explanations may be omitted as appropriate.

[0008] 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.

[0009] 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. The display devices DSPR and DSPL are aligned in the second direction Y. Such glasses 1 can be used, for example, for providing virtual reality, augmented reality, and the like. The display devices DSPR and DSPL have substantially the same configuration, and will hereinafter be described simply as the display device DSP.

[0010] FIG. 2 is a diagram showing an example of the configuration of the display device DSP shown in FIG.

[0011] 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. As will be described in detail later, at least one of the second retardation plate R2 and the reflective polarizer RP is configured to be rotatable on the XY plane.

[0012] 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.

[0013] 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.

[0014] 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 and is fixed to 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 the first retardation plate R1. As will be described later, 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.

[0015] The holographic optical element HE corresponds to an example of an optical element having a lens effect. The holographic optical element HE overlaps the display element DE and the first retardation plate R1 in the third direction Z. 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 collecting the incident light.

[0016] The second retardation plate R2 overlaps the holographic optical element HE in the third direction Z. In one example, the second retardation plate R2 is laminated on 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 it. As will be described later, 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.

[0017] The first transparent support BS1 is formed in a flat plate shape and has a first surface S1 facing the first retardation plate R1 in the third direction Z, and a second surface S2 on the opposite side of the first surface S1. The first surface S1 and the second surface S2 are both planes parallel to the XY plane. In the illustrated example, a laminate of the holographic optical element HE and the second retardation plate R2 is disposed on the second surface S2. The laminate of the holographic optical element HE and the second retardation plate R2 may be disposed on the first surface S1. Alternatively, the holographic optical element HE may be disposed on the first surface S1, and the second retardation plate R2 may be disposed on the second surface S2.

[0018] The reflective polarizer RP overlaps the second retardation plate R2 in the third direction Z via an air layer A. As the reflective polarizer RP, a multi-layer thin film type or a wire grid type can be used. 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.

[0019] The second transparent support BS2 is formed in a flat plate shape and has a third surface S3 and a fourth surface S4 on the opposite side of the third surface S3. The third surface S3 and the fourth surface S4 are both planes parallel to the XY plane. The reflective polarizing plate RP is disposed on the third surface S3. The reflective polarizing plate RP may be disposed on the fourth surface S4. The first transparent support BS1 and the second transparent support BS2 are glass substrates or resin substrates.

[0020] The optical function in the display device DSP will be briefly explained below. As shown 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 first transparent support BS1, the holographic optical element HE, and the second retardation plate R2, and is reflected by the reflective polarizing plate RP via the air layer A. The display light DL reflected by the reflective polarizing plate RP passes through the air layer A and then passes through the holographic optical element HE. The display light DL reflected by the holographic optical element HE passes through the second retardation plate R2, then passes through the air layer A and passes through the reflective polarizing plate RP, and further passes through the second transparent support BS2, and is focused on the user's pupil E by 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 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.

[0023] 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 an area of ​​the liquid crystal panel PNL that is configured to display an image.

[0024] 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 the side surface LGa of the light guide plate LG in the first direction X. 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] Light emitted from the light source LS is propagated while being totally reflected inside the light guide plate LG. Of the propagated light, light that does not meet the total reflection conditions is emitted from the light guide plate LG toward the liquid crystal panel PNL. The light emitted from the light guide plate LG is refracted by the prism sheet PS to form illumination light that is emitted along the third direction Z. The liquid crystal panel PNL selectively modulates the illumination light in the display section DA. Then, a portion of the illumination light forms linearly polarized display light DL when transmitted through the second polarizer P2.

[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 transmitted through the first phase difference plate R1 and converted into the first circularly polarized light CP1. The first circularly polarized light CP1 transmitted through the first phase difference plate R1 is transmitted through the holographic optical element HE, and then transmitted through the second phase difference plate R2 to be converted into the first linearly polarized light LP1. Of the first circularly polarized light CP1 transmitted through the first phase difference plate R1, the first circularly polarized light CP1 reflected by the holographic optical element HE is transmitted through the first phase difference plate R1 again to be converted into the second linearly polarized light, and then absorbed by the second polarizer P2. The second linearly polarized light LP2 is linearly polarized light having a polarization axis perpendicular to that of the first linearly polarized light LP1.

[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 that has passed through the second phase difference plate R2 is reflected and diffracted by the holographic optical element HE. The second circularly polarized light CP2 that has been reflected by the holographic optical element HE passes through the second phase difference plate R2 and is converted into the second linearly polarized light LP2. Of the second circularly polarized light CP2 that has passed through the second phase difference plate R2, the second circularly polarized light CP2 that has passed through the holographic optical element HE is not reflected to the user side and does not contribute to display.

[0030] The second linearly polarized light LP2, which is reflected by the holographic optical element HE and then passes through the second phase difference plate R2, 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.

[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] However, light that reaches the pupil E through an optical path different from the optical path shown by the solid line in FIG. 4 becomes so-called stray light, which leads to a decrease in display quality. In the example shown in FIG. 4, from the viewpoint of suppressing stray light, it is important that the first linearly polarized light LP1 of the light traveling from the second retarder R2 toward the reflective polarizer RP after passing through the holographic optical element HE is precisely perpendicular to the transmission axis Trp of the reflective polarizer RP. If the first linearly polarized light LP1 of the light traveling from the second retarder R2 toward the reflective polarizer RP is not precisely perpendicular to the transmission axis Trp of the reflective polarizer RP, some of the light is transmitted, generating stray light. One of the reasons why the first linearly polarized light LP1 is not precisely perpendicular to the transmission axis Trp of the reflective polarizer RP is the mismatch between the first axis angle between the transmission axis T2 of the second polarizer P2 and the slow axis of the first retarder R1 and the second axis angle between the transmission axis Trp of the reflective polarizer RP and the slow axis of the second retarder R2.

[0034] Therefore, in this embodiment, the second polarizer P2 and the first retarder R1 are fixed to each other, while the reflective polarizer RP and the second retarder R2 are configured to be relatively rotatable in the XY plane. This will be described in more detail below.

[0035] FIG. 5 is a diagram for explaining the first shaft angle θ1 and the second shaft angle θ2.

[0036] As described above, the transmission axis T2 of the second polarizer P2 is parallel to, for example, the second direction Y. The slow axis AX1 of the first retardation plate R1 intersects with the transmission axis T2 or the second direction Y in the XY plane. The first axis angle θ1 corresponds to the angle between the transmission axis T2 and the slow axis AX1. In order to convert the first linearly polarized light LP1 transmitted through the second polarizer P2 into the first circularly polarized light CP1, the first axis angle θ1 is set to 45°.

[0037] The transmission axis Trp of the reflective polarizer RP is, for example, parallel to the first direction X. The slow axis AX2 of the second retardation plate R2 intersects with the transmission axis Trp or the first direction X in the XY plane. The second axis angle θ2 corresponds to the angle between the transmission axis Trp and the slow axis AX2. The second axis angle θ2 is set to be the same as the first axis angle θ1, and is set to 45° here.

[0038] The third axis angle θ3, which corresponds to the angle between the slow axis AX1 and the slow axis AX2, is set to 90°.

[0039] In order to realize a state in which the first linearly polarized light LP1 and the transmission axis Trp of the reflective polarizer RP are precisely perpendicular to each other, it is sufficient to match the first axis angle θ1 and the second axis angle θ2. For this purpose, at least one of the second retardation plate R2 and the reflective polarizer RP is configured to be rotatable on the XY plane, and when a mismatch occurs between the first axis angle θ1 and the second axis angle θ2, the second axis angle θ2 can be matched to the first axis angle θ1 by rotating at least one of the second retardation plate R2 and the reflective polarizer RP. This makes it possible to suppress undesired stray light and suppress a deterioration in display quality.

[0040] An example in which the second transparent support BS2 on which the reflective polarizing plate RP is arranged is rotated will be described below.

[0041] FIG. 6 is a diagram showing an example of the configuration of the adjustment mechanism 3 that adjusts the rotation angle of the second transparent support BS2.

[0042] In the glasses 1, a display device DSPR for the right eye and a display device DSPL for the left eye are each held by a frame 2. In each of the display devices DSPR and DSPL, a second transparent support BS2 on which a reflective polarizing plate RP is arranged is formed in a circular shape. For example, as shown in an enlarged view, the second transparent support BS2 of the display device DSPR has a circular outer edge Ebs. The dial-type adjustment mechanism 3 has a circular contact portion 3a that contacts the outer edge Ebs.

[0043] In the illustrated example, when the adjustment mechanism 3 rotates clockwise, the second transparent support BS2 rotates counterclockwise around its center Obs as the rotation axis. That is, the adjustment mechanism 3 can adjust the rotation angle of the second transparent support BS2. As the second transparent support BS2 rotates, the reflective polarizing plate RP rotates. This allows the orientation of the transmission axis Trp of the reflective polarizing plate RP in the XY plane to be adjusted.

[0044] For example, if the diameter of the second transparent support BS2 is 60 mm and the diameter of the contact portion 3a is 6 mm, when the adjustment mechanism 3 rotates by 10°, the second transparent support BS2 and the reflective polarizing plate RP rotate by 1°.

[0045] Although not shown, the first transparent support BS1 on which the second retardation plate R2 is disposed is fixed to the frame 2 and does not rotate.

[0046] In this way, by rotating the reflective polarizer RP with respect to the fixed second retardation plate R2, the second axis angle θ2 can be finely adjusted and aligned with the first axis angle θ1.

[0047] FIG. 7 is a diagram showing another example of the configuration of the adjustment mechanism 3 that adjusts the rotation angle of the second transparent support BS2.

[0048] In each of the display devices DSPR and DSPL, the second transparent support BS2 on which the reflective polarizing plate RP is disposed is formed in a non-circular shape. For example, as shown in an enlarged view, the second transparent support BS2 of the display device DSPR is formed in a substantially rectangular shape and has four sides E1 to E4 as an outer edge Ebs. Side E1 faces side E3, and side E2 faces side E4.

[0049] The screw-type adjustment mechanism 3 contacts the vicinity of the side E1 of the side E2. The vicinity of the corner where the sides E3 and E4 intersect contacts the fixed point 4 of the frame 2. Elastic bodies 5 such as springs are respectively interposed between the side E1 and the frame 2, and between the side E4 and the frame 2. In the illustrated example, when the adjustment mechanism 3 is rotated and pushed toward the side E2, the second transparent support BS2 rotates counterclockwise around the fixed point 4 as the rotation axis. In other words, the adjustment mechanism 3 can adjust the rotation angle of the second transparent support BS2. As the second transparent support BS2 rotates, the reflective polarizing plate RP rotates. This makes it possible to adjust the orientation of the transmission axis Trp of the reflective polarizing plate RP in the XY plane.

[0050] For example, if the second transparent support BS2 is a square, the length of each of the sides E1 to E4 is 50 mm, the screw diameter of the adjustment mechanism 3 is 2 mm, and the screw pitch of the adjustment mechanism 3 is 0.25 mm, when the adjustment mechanism 3 rotates once, the second transparent support BS2 and the reflective polarizing plate RP rotate 0.46°.

[0051] Although not shown, the first transparent support BS1 on which the second retardation plate R2 is disposed is fixed to the frame 2 and does not rotate.

[0052] In this way, by rotating the reflective polarizer RP with respect to the fixed second retardation plate R2, the second axis angle θ2 can be finely adjusted and aligned with the first axis angle θ1.

[0053] 6 and 7, the second transparent support BS2 may be fixed to the frame 2, and the first transparent support BS1 may be rotated by the adjustment mechanism 3. In this case, the second retardation plate R2 rotates with respect to the fixed reflective polarizing plate RP, thereby enabling fine adjustment of the second axis angle θ2.

[0054] Next, the influence of reflection at the interfaces included in the display device DSP will be examined.

[0055] FIG. 8 is a diagram for explaining reflected light at an interface included in the display device DSP shown in FIG.

[0056] The interfaces considered here are an interface B1 between the second retardation plate R2 and the air layer A, and an interface B2 between the reflective polarizing plate RP and the air layer A.

[0057] When a part of the light traveling from the holographic optical element HE toward the second phase difference plate R2 is reflected at the interface B1, this reflected light is not reflected toward the pupil E and does not contribute to display. Even if a part of the light traveling from the second retardation plate R2 to the reflective polarizer RP is reflected by the interface B2, this reflected light also does not reach the pupil E and does not contribute to display.

[0058] When a portion of the light traveling from the reflective polarizer RP toward the second retardation plate is reflected at the interface B2, this reflected light remains in the polarization state of the first linear polarization, does not pass through the reflective polarizer RP, and does not contribute to the display. When a part of the light traveling from the reflective polarizer RP toward the second retardation plate is reflected at the interface B1, this reflected light also does not pass through the reflective polarizer RP and does not contribute to display.

[0059] In other words, according to this embodiment, in addition to being able to suppress stray light caused by mismatch between the first axis angle θ1 and the second axis angle θ2, it is also possible to suppress stray light caused by undesired reflections at the interfaces B1 and B2.

[0060] FIG. 9 is a diagram for explaining reflected light at an interface included in a display device DSP as a comparative example.

[0061] The illustrated comparative example differs from the present embodiment shown in Fig. 8 in that a second retardation plate and a reflective polarizing plate RP are laminated, and an air layer A is interposed between the holographic optical element HE and the second retardation plate R2. The interfaces considered here are the interface B11 between the holographic optical element HE and the air layer A, and the interface B12 between the second retardation plate R2 and the air layer A.

[0062] The reflected light to be noted here is the light reflected at interfaces B11 and B12 among the light reflected by the reflective polarizer RP. The light reflected at interfaces B11 and B12 toward the reflective polarizer RP is converted into the second linearly polarized light LP2 when it passes through the second retardation plate R2. As a result, a part of the reflected light on an optical path different from the optical path shown by the solid line passes through the reflective polarizer RP and reaches the pupil E as stray light, resulting in a deterioration in display quality.

[0063] Moreover, in the comparative example shown here, the second polarizer P2 and the first retardation plate R1 are stacked, and the second retardation plate R2 and the reflective polarizer RP are stacked, so that when a mismatch occurs between the first axis angle θ1 and the second axis angle θ2, neither the first axis angle θ1 nor the second axis angle θ2 can be adjusted, which may result in a further deterioration of the display quality.

[0064] Compared to such a comparative example, this embodiment is advantageous in that it can suppress stray light and suppress deterioration of display quality.

[0065] FIG. 10 is a diagram showing another example of the configuration of the display device DSP shown in FIG. The configuration example shown in Fig. 10 differs from the configuration example shown in Fig. 2 in that the first retardation plate R1, the second retardation plate R2, and the reflective polarizing plate RP are each covered with an antireflection layer AR. In the illustrated example, the first surface S1 of the first transparent support BS1 and the fourth surface S4 of the second transparent support BS2 are also each covered with an antireflection layer AR. 10, undesired reflections are suppressed at the interface between the first retardation plate R1 and the air layer, the interface between the first surface S1 and the air layer, the interface between the second retardation plate R2 and the air layer, the interface between the reflective polarizer RP and the air layer, and the interface between the fourth surface S4 and the air layer, thereby preventing degradation of display quality.

[0066] FIG. 11 is a diagram showing another example of the configuration of the display device DSP shown in FIG. The configuration example shown in FIG. 11 differs from the configuration example shown in FIG. 2 in that, as an optical element having a lens effect, instead of a holographic optical element HE, a semi-transparent layer (half mirror) HM is used, the side facing the second phase difference plate R2 being formed in a concave shape. In the illustrated example, the first transparent support BS1 is formed as a plano-convex lens. That is, in the first transparent support BS1, the first surface S1 is formed as a convex surface, and the second surface S2 is formed as a flat surface parallel to the XY plane. The semi-transmitting layer HM is disposed on the first surface S1. The second retardation plate R2 is disposed on the second surface S2.

[0067] The optical function in the display device DSP will be briefly explained below. As shown 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 semi-transmitting layer HM, then passes through the first transparent support BS1 and the second retardation plate R2, and is reflected by the reflective polarizing plate RP via the air layer A. The display light DL reflected by the reflective polarizing plate RP passes through the air layer A and passes through the second retardation plate R2 and the first transparent support BS1, and is reflected by the semi-transmitting layer HM. The display light DL reflected by the semi-transmitting layer HM passes through the first transparent support BS1 and the second retardation plate R2, then passes through the air layer A and passes through the reflective polarizing plate RP, and is further transmitted through the second transparent support BS2, and is focused on the user's pupil E by the lens action of the semi-transmitting layer HM.

[0068] In this configuration example as well, the same effects as those in the above configuration example can be obtained.

[0069] Although not shown, an anti-reflection layer AR may be applied in the same manner as in the configuration example shown in FIG.

[0070] Next, the inventors verified the influence of the misalignment between the first axis angle θ1 and the second axis angle θ2 by simulation.

[0071] FIG. 12 is a diagram showing the simulation results. The simulation conditions are as follows: The orientation of the transmission axis T2 of the second polarizer P2 in the XY plane is taken as the reference, and the transmission axis T2 is set to an orientation of 0°. The slow axis AX1 of the first retardation plate R1 is set to an orientation of 45°, and the first axis angle θ1 is 45°. The slow axis AX2 of the second retardation plate R2 is designed to have an orientation of 135°, and the amount of deviation from the design value is represented as Δθr. The transmission axis Trp of the reflective polarizing plate RP is designed to have an orientation of 90°, and the amount of deviation from the designed value is represented as Δθp. The retardation Δn·d of the first retardation plate R1 and the second retardation plate R2 is both 144 nm. Δn is a parameter indicating the refractive index anisotropy or birefringence of each retardation plate. d corresponds to the thickness of each retardation plate.

[0072] 12, the horizontal axis represents the amount of deviation Δθr (°), and the vertical axis represents the amount of leakage light (au). As described with reference to FIG. 9, leakage light is undesired stray light caused by a mismatch between the second axis angle θ2 and the first axis angle θ1, and corresponds to light that passes through the reflective polarizing plate RP and reaches the pupil E.

[0073] The solid line in the figure shows the simulation results of the amount of leakage light that occurs when the misalignment amount Δθp is 0°. When the misalignment amount Δθr is 0°, the second axis angle θ2 is equal to the first axis angle θ1, which is 45°. In this case, the amount of leakage light is at a minimum. It was confirmed that as the absolute value of the misalignment amount Δθr increases, the difference between the first axis angle θ1 and the second axis angle θ2 increases, and the amount of leakage light increases.

[0074] The dashed line in the figure shows the simulation results of the amount of leakage light that occurs when the misalignment amount Δθp is 2°. When the misalignment amount Δθr is 2°, the second axis angle θ2 is equal to the first axis angle θ1, which is 45°. In this case, the amount of leakage light is at a minimum. It was confirmed that as the misalignment amount Δθr increases or decreases from 2°, the difference between the first axis angle θ1 and the second axis angle θ2 increases, and the amount of leakage light increases.

[0075] The dashed dotted line in the figure shows the simulation results of the amount of leaking light that occurs when the misalignment amount Δθp is 5°. When the misalignment amount Δθr is 5°, the second axis angle θ2 is equal to the first axis angle θ1, which is 45°. In this case, the amount of leaking light is at a minimum. It was confirmed that as the misalignment amount Δθr increases or decreases from 5°, the difference between the first axis angle θ1 and the second axis angle θ2 increases, and the amount of leaking light increases.

[0076] As described above, according to the present embodiment, it is possible to provide a display device capable of suppressing degradation of display quality.

[0077] 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]

[0078] DSP…display device DE: Display element PNL: Liquid crystal panel IL: Illumination device P1: First polarizing plate P2: Second polarizing plate R1: First retardation plate R2: Second retardation plate RP: Reflective polarizing plate HE: Holographic optical element HM: Semi-transparent layer SB1...First transparent support SB2...Second transparent support 1... Glasses 2... Frame 3... Adjustment mechanism

Claims

1. A display element configured to emit linearly polarized display light; a first retardation plate overlapping the display element; an optical element overlapping the display element and the first retardation plate and having a lens function; A second retardation plate overlapping the optical element; a reflective polarizing plate overlapping the second retardation plate via an air layer and rotatable relative to the second retardation plate; A display device comprising:

2. 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. 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.

4. The display device according to claim 1 , wherein the optical element is a holographic optical element and is configured to reflect the light reflected by the reflective polarizer toward the reflective polarizer.

5. 2. The display device according to claim 1, wherein the optical element is a semi-transmissive layer having a concave surface facing the second retardation plate, and is configured to reflect light reflected by the reflective polarizing plate toward the reflective polarizing plate.

6. a first transparent support on which the optical element and a second retardation plate are disposed; The display device according to claim 1 , further comprising: a second transparent support on which the reflective polarizing plate is disposed.

7. The display device according to claim 1 , wherein the first retardation plate, the second retardation plate, and the reflective polarizer are each covered with an anti-reflection layer.

8. The display device according to claim 6 , further comprising an adjustment mechanism for adjusting a rotation angle of the first transparent support or the second transparent support.

9. The first transparent support or the second transparent support is formed in a circular shape, The display device according to claim 8 , wherein the adjustment mechanism is configured to rotate the display device about a center of the first transparent support or the second transparent support as a rotation axis.

10. The display device according to claim 8 , wherein the adjustment mechanism is configured to rotate about a fixed point in contact with an outer edge of the first transparent support or the second transparent support as a rotation axis.

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