Light guide plate and image display device using the same

Abstract

To provide a light guide plate that can improve the transmittance of external light, while reducing light quantity unevenness with high efficiency in light utilization.SOLUTION: A light guide plate has a first surface and a second surface that are parallel to each other, and first to third separation surfaces that are inclined relative to the first surface. The angle (°) of the separation surfaces relative to the normal of the first surface, the incidence angle of an n-th (n: natural number) light beam incident on the first surface, and the reflectance of an m-th (m: 1, 2, 3) separation surface relative to light with a dominant wavelength incident at an incidence angle of 90-θn+ψ (°), are each appropriately set.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a light guide plate that guides a display image to a viewer's pupil. [Background technology]

[0002] Conventionally, there is known an image display device equipped with a light guide plate that guides a display image to the pupil of an observer. Fig. 12 is a conceptual diagram of light beams propagating inside the light guide plate of a conventional image display device. Light beams L10, L20, and L30 emitted from pixels of an image display element 110 pass through a projection optical system 120, enter an entrance section 131 at different angles of incidence, and are deflected, and then propagate inside the light guide plate 130 at different total reflection angles α10, α20, and α30 (α10<α20<α30). A portion of the light beams that enter the exit section 132 are deflected and head toward the pupil SP of the observer, and the other light beams propagate inside the light guide plate 130 by total reflection and enter the exit section 132. In conventional image display devices, the width of the area (effective area) where the lights L10, L20, and L30 overlap at the position of the observer's pupil SP is smaller than the width of the light beam emitted from the emission section 132, and a large amount of unnecessary light is generated relative to the effective area, significantly reducing the light utilization efficiency.

[0003] Patent Document 1 discloses a configuration in which an appropriate incident angle range with high reflectance and low incidence angle dependency is set for a plurality of separation surfaces in order to increase the intensity of each light ray incident on the observer's pupil. Patent Document 2 discloses a configuration in which different light reflectances are set for a plurality of semi-transmitting layers based on angle dependency in order to increase light guide efficiency, so that only the light of the angle component incident on the observer's pupil is reflected and the light of the other angle components is transmitted. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-165743 A [Patent Document 2] International Publication No. 2018 / 221026 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the configurations of Patent Documents 1 and 2, the reflectance is constant within the range of angles of incidence of the separation surface in the optical path along which the light from the image display element is deflected to the observer's pupil. This causes the light beams reflected by the separation surface at different exit angles to be non-uniform, resulting in non-uniform luminance within the range of viewing angles incident on the observer's pupil and a decrease in the transmittance of external light.

[0006] An object of the present invention is to provide a light guide plate capable of improving the transmittance of outside light while reducing unevenness in the amount of light with high light utilization efficiency. [Means for solving the problem]

[0007] A light guide plate according to one aspect of the present invention has a first surface and a second surface that are parallel to each other, and first to third separation surfaces that are inclined with respect to the first surface, and the angle [°] of each separation surface with respect to the normal line of the first surface is defined as ψ, and the angle of incidence [°] of the nth light ray (n: natural number) that is incident on the first surface is defined as θ. n (θ 1 +5<θ 2 <θ 3 -5), the incidence angle is 90-θ n The reflectance of the mth (m: 1, 2, 3) separation surface for the light of the dominant wavelength incident at +ψ[°] is Rs1 mn When Rs1 21 >Rs1 22 >Rs1 23 Rs1 31 <Rs1 32 Rs1 31 <Rs1 32 The present invention is characterized in that the following conditional expression is satisfied: Effect of the Invention

[0008] According to the present invention, it is possible to provide a light guide plate capable of improving the transmittance of outside light while reducing unevenness in the amount of light with high light utilization efficiency. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram illustrating the configuration of a light guide plate according to the first embodiment. [Diagram 2] FIG. 2 is a configuration diagram of a light source unit according to the first embodiment. [Diagram 3] 1 is a diagram showing the reflectance of S-polarized light versus the angle of incidence of the dielectric film in Example 1. FIG. [Figure 4] FIG. 4 is a diagram showing the reflectance of S-polarized light of each dielectric film in Example 1. [Diagram 5] 4 is a diagram showing the transmittance of S-polarized light of the outside world in Example 1. FIG. [Figure 6] 1 is a diagram showing the reflectance of P-polarized light versus the angle of incidence of the dielectric film in Example 1. FIG. [Figure 7] FIG. 4 is a diagram showing the transmittance of unpolarized light from the outside world in Example 1. [Figure 8] 4 is a diagram showing the reflectance of S-polarized light on the first to third separation surfaces in Example 1. FIG. [Figure 9] 13 is a diagram showing the reflectance of S-polarized light on the fourth and fifth separation surfaces in Example 1. FIG. [Figure 10] FIG. 11 is a diagram illustrating the configuration of a light guide plate according to a second embodiment. [Figure 11] FIG. 11 is a configuration diagram of a light guide plate according to a third embodiment. [Figure 12] FIG. 13 is a conceptual diagram of a light flux propagating inside a light guide plate of a conventional image display device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to refer to the same components, and duplicated descriptions will be omitted. EXAMPLES

[0011] 1 is a configuration diagram of an image display device 30 of this embodiment. The image display device 30 has a light source unit 31 and a light guide plate 32. The light guide plate 32 is made of a transparent material such as glass or plastic, and has a first surface 32a and a second surface 32b that are parallel to each other, and a plurality of separation surfaces 32c that are inclined at a predetermined angle with respect to the first surface 32a. The plurality of separation surfaces 32c have the property of reflecting light at a predetermined angle with a predetermined reflectance, and are made of a plurality of layers including a high refractive index film and a low refractive index film. Generally, TiO 2 , Ta 2 O 5 , ZnS, etc. as a film material, and SiO 2 , MgF 2 , Al 2 O 3 In order to improve the transmittance of the outside world, an anti-reflection film is deposited on the first surface 32a and the second surface 32b.

[0012] FIG. 2 is a configuration diagram of the light source unit 31. The light source unit 31 includes an RGB laser light source 41, a cross dichroic prism 42, an illumination optical system 43, a liquid crystal panel 44 as an image display element, and a condenser lens 45. The RGB laser light (P polarized light) emitted from the laser light source 41 is combined by the cross dichroic prism 42 and emitted to the illumination optical system 42. The laser light incident on the illumination optical system 42 uniformly illuminates the liquid crystal panel 44, and the image light (S polarized light) modulated by the liquid crystal panel 44 is condensed at a predetermined position of the light guide plate 32 via the condenser lens 45. The light (P polarized light) not modulated by the liquid crystal panel 44 is absorbed by a polarizing plate (not shown) or the like. The P polarized light and the S polarized light correspond to the polarization direction defined by the separation surface 32c of the light guide plate 32. In this embodiment, the main wavelengths of the laser light source 41 are 450 nm, 520 nm, and 640 nm. Although the present embodiment shows a configuration of an image display device that emits light of three colors, RGB, it may be configured to emit monochromatic light using only a G laser light source, for example.

[0013] Also, a reflective liquid crystal panel (LCOS) or a digital mirror device in which tiny mirrors form pixels may be used as the image display element. Also, the light source unit 11 may be configured with a laser light source and a MEMS (Micro Electro Mechanical System). Furthermore, the light source unit 11 may be an OLED (Organic Light Emitting Diode) or a MicroLED.

[0014] Image light polarized in a predetermined direction (S-polarized light) emitted from light source unit 31 enters light guide plate 32, undergoes total reflection, propagates through light guide plate 32, and is split into multiple light beams by multiple separation surfaces 32c and guided to the viewer's pupil SP. Multiple separation surfaces 32c are composed of first to thirteenth dielectric films M1 to 13. FIG. 3 is a diagram showing the reflectance of S-polarized light versus the angle of incidence of green light with a dominant wavelength of 520 nm on the first to thirteenth dielectric films M1 to 13. Red light with a dominant wavelength of 640 nm and blue light with a dominant wavelength of 450 nm also show similar S-polarized reflectance characteristics.

[0015] In this embodiment, the incidence angle θ 1 ,θ 2 ,θ 3 (θ 1 +5<θ 2 <θ 3 The light rays from the first surface 32a (second surface 32b) to the separation surface are respectively designated as the first light ray L31, the second light ray L32, and the third light ray L33. If the angle [°] of each separation surface with respect to the normal of the first surface 32a (second surface 32b) is designated as ψ, the incident angle ψ1 of the nth light ray (n: natural number) from the first surface 32a to the separation surface is n [°] is 90-θn+ψ. Also, the angle of incidence ψ2 of the nth light ray from the second surface 32b to the separation surface n [°] is 90-θn-ψ. In this embodiment, the angle ψ is 30°, and the incident angle θ 1 ,θ 2 ,θ 3 are 50°, 60°, and 70°, respectively, and the incidence angle ψ1 1 , ψ1 2 , ψ1 3 ,ψ2 1 ,ψ2 2 ,ψ2 3are 70°, 60°, 50°, 10°, 0°, and −10°, respectively. The second light ray L32 is the center of the light beam propagating within the light guide plate 32.

[0016] The first light ray L31 is split into multiple light rays by the first to seventh dielectric films M1 to M7 and is guided to the pupil SP. The second light ray L32 passes through the first to third dielectric films M1 to M3, is split into multiple light rays by the fourth to tenth dielectric films M4 to M10 and is guided to the pupil SP. The third light ray L33 passes through the first to sixth dielectric films M1 to M6, is split into multiple light rays by the seventh to thirteenth dielectric films M7 to M13 and is guided to the pupil SP. Therefore, the light beam can be condensed on the pupil SP, thereby achieving high light utilization efficiency.

[0017] 4(a) to 4(c) show the incidence angle ψ1 of green light with a dominant wavelength of 520 nm. 1 FIG. 1 is a diagram showing the reflectance of S-polarized light for each dielectric film when the incident angle ψ1 is 70°, 60°, and 50°. 1 When the incident angle ψ1 is 70°, the reflectance increases from the first dielectric film M1 to the seventh dielectric film M7, and decreases from the eighth dielectric film M8 to the thirteenth dielectric film M13. 1 When the incident angle ψ1 is 60°, the reflectance is low in the first to third dielectric films M1 to M3, increases from the fourth dielectric film M4 to the tenth dielectric film M10, and decreases from the eleventh dielectric film M11 to the thirteenth dielectric film M13. 1 When the angle is 50°, the reflectance is low in the first to sixth dielectric films M1 to M6 and increases from the seventh dielectric film M7 to the thirteenth dielectric film M13. By making the reflectance of the dielectric films that collect the light beam on the pupil SP increase in the x direction, the light intensity distribution within the pupil SP can be made uniform.

[0018] Generally, the reflectance is high on the high incidence angle side, but by lowering the reflectance on the high incidence angle side of the dielectric films at the back in the x direction (especially the tenth to thirteenth dielectric films M10 to M13), it is possible to increase the transmittance while reducing the angular unevenness in the transmittance of external light.

[0019] Fig. 5 is a diagram showing the relationship between the angle of incidence of external light incident on light guide plate 32 for green light with a dominant wavelength of 520 nm and the average transmittance of S-polarized light of first to thirteenth dielectric films M1 to 13. Fig. 5(a) is a schematic diagram defining the angle of incidence of external light on light guide plate 32, where ω(+) indicates a positive angle and ω(-) indicates a negative angle. Fig. 5(b) shows the average transmittance versus the angle of incidence for this embodiment and a conventional example (when the reflectance on the high incidence angle side is not reduced).

[0020] Since light in the outside world is generally unpolarized, in order to reduce the reflectance of P-polarized light, the first to thirteenth dielectric films M1 to M13 are formed at an incidence angle ψ1 1 , ψ1 3 are 70° and 50°, respectively, to satisfy the following Brewster condition.

[0021]

number

[0022] where n H is the refractive index of the high refractive index film that constitutes the dielectric film for light of the dominant wavelength. L is the refractive index of the low refractive index film that constitutes the dielectric film for light of the dominant wavelength. G is the refractive index of the light guide plate 32 for light with a dominant wavelength of 520 nm. H ,n L ,n G are 2.402, 1.457, and 1.518, respectively, and the Brewster condition κ is 55.1°. Fig. 6 is a diagram showing the reflectance of P-polarized light versus the angle of incidence of light with a dominant wavelength of 520 nm for green light for the first to thirteenth dielectric films M1 to M13. The reflectance at angles of incidence between 50° and 60° is nearly 0%, and the reflectance can be reduced at angles of incidence between 50° and 70°.

[0023] In this embodiment, the viewing angle H in the x direction is 38.6°, and the upper limit value ψ1 of the angular distribution of the light beams propagating within the light guide plate 32 and incident on the multiple separation surfaces 32c is H and the lower limit ψ1 L is obtained by the following formula:

[0024] ψ1 H =ψ1 2 +SN(H / 2) ψ1 L =ψ1 2 -SN(H / 2) SN(x)=sin -1 [(sinx) / nG] Here, the unit of SN(x) is °. In this embodiment, the upper limit value ψ1 H and the lower limit ψ1 L are 72.5° and 47.5°, respectively. 1 , ψ1 3 is defined as follows using the viewing angle in the x direction:

[0025] ψ1 1 =ψ1 2 +SN(H / 2)×0.8 ψ1 3 =ψ1 2 -N(H / 2)×0.8 Fig. 7 is a diagram showing the relationship between the angle of incidence of external green light having a dominant wavelength of 520 nm that is incident on light guide plate 32 and the average transmittance of unpolarized light of first to thirteenth dielectric films M1 to M13. As shown in Fig. 7, it is possible to improve the transmittance of external light while reducing unevenness in the amount of light with high light utilization efficiency.

[0026] The conditions satisfied by this embodiment are described below. The first dielectric film M4 is the first separation surface, the seventh dielectric film M7 is the second separation surface, and the tenth dielectric film M10 is the third separation surface. If the eyebox size is d (mm), the surface that passes through or is closest to the normal line from the center of the eyebox is the second separation surface. Also, the surface that passes through or is closest to the normal line from the position d / 2 in the negative x direction from the center of the eyebox is the first separation surface, and the surface that passes through or is closest to the normal line from the position d / 2 in the positive x direction from the center of the eyebox is the third separation surface. Figure 8 is a diagram showing the reflectance of S-polarized light versus the angle of incidence of light of the dominant wavelength for the first to third separation surfaces. The nth light ray (incident angle ψ1 n ) is the reflectance of S-polarized light at the mth (m: 1, 2, 3) separation surface Rs1 mnIn this case, the first to third separation surfaces satisfy the following conditional expressions (1) to (3).

[0027] Rs1 21 >Rs1 22 >Rs1 23 (1) Rs1 31 <Rs1 32 (2) Rs1 31 <Rs1 32 (3) If conditional formula (1) is not satisfied, luminance unevenness will be large, and if conditional formulas (2) and (3) are not satisfied, the transmittance of external light will increase.

[0028] It is preferable that the first to third separation surfaces satisfy the following conditional expressions (1a) to (3a).

[0029] Rs1 21 >1.2×Rs1 22 >1.2×Rs1 23 (1a) 1.2×Rs1 31 <Rs1 32 (2a) 1.2×Rs1 31 <Rs1 32 (3a) It is more preferable that the first to third separation surfaces satisfy the following conditional expressions (1b) to (3b).

[0030] Rs1 21 >1.4×Rs1 22 >1.4×Rs1 23 (1b) 1.4×Rs1 31 <Rs1 32 (2b) 1.4×Rs1 31 <Rs1 32 (3b) The reflectance of the first separation surface satisfies the following conditional expression (4).

[0031] Rs1 11 >Rs1 12 >Rs1 13 (4) If condition (4) is not satisfied, significant unevenness in luminance occurs.

[0032] It is preferable that the reflectance of the first separation surface satisfies the following conditional formula (4a).

[0033] Rs1 11 >1.2×Rs1 12 >1.2×Rs1 13 (4a) It is further preferable that the reflectance of the first separation surface satisfies the following conditional formula (4b).

[0034] Rs1 11 >1.4×Rs1 12 >1.4×Rs1 13 (4b) The nth ray (incident angle ψ2 n ) is the reflectance of S-polarized light of the mth separation surface at Rs2 mn When this is set, it is preferable to satisfy the following conditional expression (5):

[0035] Rs2 m3 <0.050 (5) If conditional formula (5) is deviated from, not only will the amount of unnecessary light in the light guide plate 22 increase, causing ghost light, but the light utilization efficiency will also decrease.

[0036] It is more preferable that the following conditional expression (5a) be satisfied.

[0037] Rs2 m3 <0.035 (5a) It is further preferable that the following conditional expression (5b) be satisfied:

[0038] Rs2 m3 <0.020 (5b) The nth ray (incident angle ψ1 n ) is the reflectance of P-polarized light at the mth separation surface Rp1 mn When this is set, it is preferable to satisfy the following conditional expression (6):

[0039] Rs1 22 >2×Rp122 (6) If conditional formula (6) is deviated from, the transmittance of external light passing through the light guide plate 22 drops significantly.

[0040] It is more preferable that the following conditional expression (6a) be satisfied.

[0041] Rs1 22 >3×Rp1 22 (6a) It is further preferable that the following conditional expression (6b) be satisfied:

[0042] Rs1 22 >5×Rp1 22 (6b) It is preferable that the angle ψ [°] of each of the plurality of separation surfaces 32c with respect to the normal to the first surface 32a (second surface 32b) satisfies the following conditional expression (7).

[0043] 5<ψ<45 (7) If the upper or lower limit of condition (7) is exceeded, the incidence angle ψ1 n becomes smaller, making it difficult to satisfy the Brewster condition, and the transmittance of light from the outside world decreases significantly.

[0044] It is more preferable that the following conditional expression (7a) be satisfied.

[0045] 10<ψ<42 (7a) It is further preferable that the following conditional expression (7b) be satisfied:

[0046] 20<ψ<39 (7b) External light is generally unpolarized, and in order to reduce the reflectance of P-polarized light, it is preferable that the second separation surface satisfy the following conditional expression (8).

[0047]

number

[0048] In addition, n His the refractive index of the first film, which has a higher refractive index for the dominant wavelength light among the first and second films, whose total thickness is on the second separation surface. n L is the refractive index of the second film, which has a lower refractive index for light of the dominant wavelength among the first and second films and has a total film thickness on the second separation surface.

[0049] If the upper or lower limit of condition (8) is exceeded, the Brewster condition cannot be satisfied within the angular range of the effective luminous flux, and the transmittance of external light drops significantly.

[0050] It is more preferable that the following conditional expression (8a) be satisfied.

[0051]

number

[0052] It is further preferable that the following conditional expression (8b) be satisfied:

[0053]

number

[0054] The dielectric film of this embodiment has a film characteristic that combines the characteristics of a polarization separation film and a half mirror film, so that the incident angle ψ 2 In order to separate the polarized light at an angle of 60°, it is preferable that the difference in refractive index between the high refractive index film and the low refractive index film is large, and it is preferable that the refractive index of the substrate is low. Specifically, it is preferable that the following conditional expressions (9) and (10) are satisfied.

[0055] n H -n L ≧0.6 (9) n G ≦1.7 (10) If the lower limit of condition (9) or the upper limit of condition (10) is exceeded, the Brewster condition cannot be satisfied, and the transmittance of external light drops significantly.

[0056] It is more preferable that the following conditional expressions (9a) and (10a) be satisfied.

[0057] n H -n L ≧0.7 (9a) n G ≦1.65 (10a) It is further preferable that the following conditional expressions (9b) and (10b) be satisfied.

[0058] n H -n L ≧0.8 (9b) n G ≦1.60 (10b) In order to design the dielectric film, it is preferable to satisfy the following conditional formula (11), where R [nm] is the central wavelength of at least one spectrum of the light beam emitted from the light source, and W [nm] is the half-width of the spectrum.

[0059] 0.00 <W / R<0.03 (11) In this embodiment, the central wavelength R is 450 nm, 520 nm, or 640 nm, which are the main wavelengths of the laser light source 41. If the upper limit value of conditional formula (11) is exceeded, it is necessary to achieve a predetermined reflectance over a wide wavelength range, which makes film design very difficult, resulting in a decrease in light utilization efficiency and uneven brightness.

[0060] It is more preferable that the following conditional expression (11a) be satisfied.

[0061] 0.00 <W / R<0.02 (11a) It is further preferable that the following conditional expression (11b) be satisfied:

[0062] 0.000 <W / R<0.015 (11b) Table 1 shows the membrane configurations of the first to third separation surfaces. Table 1 (unit: nm) JPEG2025063481000006.jpg23598

[0063] The total thickness of the high refractive index film of the second separation film (the seventh dielectric film M7) is M H [nm], the total thickness of the low refractive index film is M L When expressed in [nm], it is preferable to satisfy the following conditional expressions (12) and (13).

[0064] M H >400 (12) M L >300 (13) The second separation film has film properties that combine the properties of a polarization separation film and a half mirror film, and requires about twice as many film layers as a general film. Therefore, if the lower limits of conditional expressions (12) and (13) are exceeded, it is difficult to achieve the desired performance.

[0065] It is more preferable to satisfy the following conditional expressions (12a) and (13a).

[0066] M H >500 (12a) M L >400 (13a) It is further preferable that the following conditional expressions (12b) and (13b) be satisfied.

[0067] M H >600 (12b) M L >500 (13b) The number of membrane layers of the second separation membrane is preferably 20 or more. If the number of membrane layers is small, it is difficult to achieve the desired performance. The number of membrane layers of the second separation membrane is more preferably 25 or more, and further preferably 30 or more.

[0068] The second dielectric film M2 is a fourth separation surface, and the twelfth dielectric film M12 is a fifth separation surface. Fig. 9 is a diagram showing the reflectance of S-polarized light versus the angle of incidence of light of the dominant wavelength on the fourth and fifth separation surfaces. It is preferable that the fourth separation surface satisfies the following conditional expressions (14) to (16).

[0069] Rs1 42 <0.05 (14) Rs1 43 <0.05 (15) Rs1 42 <Rs1 41 (16) Incident angle ψ1 2 , ψ1 3 However, the 60° and 50° rays are partially reflected by the fourth separation surface, resulting in a decrease in light utilization efficiency and ghost light.

[0070] It is more preferable to satisfy the following conditional expressions (14a) to (16a).

[0071] Rs1 42 <0.03 (14a) Rs1 43 <0.04 (15a) Rs1 42 <Rs1 41 (16a) It is further preferable that the following conditional expressions (14b) to (16b) be satisfied.

[0072] Rs1 42 <0.02 (14b) Rs1 43 <0.03 (15b) Rs1 42 <Rs1 41 (16b) It is preferable that the fifth separation surface satisfies the following conditional expression (17).

[0073] Rs1 52 <Rs1 53 (17) If condition (17) is deviated from, the transmittance of external light increases.

[0074] It is more preferable that the following conditional expression (17a) be satisfied:

[0075] 1.2×Rs1 52 <Rs1 53 (17a) It is further preferable that the following conditional expression (17b) be satisfied:

[0076] 1.4×Rs1 52 <Rs1 53 (17b) When a three-color (RGB) light source is used, it is desirable to satisfy each conditional expression at the peak wavelength (dominant wavelength) of each of the red, green, and blue bands. EXAMPLES

[0077] 10 is a configuration diagram of an image display device 120 of this embodiment. The image display device 120 has a light source unit 121 and a light guide plate 122. The light guide plate 122 has a first surface 122a and a second surface 122b that are parallel to each other, a plurality of separation surfaces 122c inclined at a predetermined angle with respect to the first surface 122a, and a deflection means 122d.

[0078] The plurality of separation surfaces 122c have first to thirteenth dielectric films M1 to M13 deposited on every two separation surfaces in the same manner as in Example 1. This makes it possible to increase the number of separation surfaces with the same number of dielectric films, thereby enabling the miniaturization of the light guide plate 122. The deflection means 122d is composed of a diffraction element, a metasurface, a holographic element, or the like, and deflects the light beam from the light source 121 to propagate within the light guide plate 122.

[0079] In this embodiment, the same dielectric film is disposed on every two separation surfaces, but the same dielectric film may be disposed on every three separation surfaces. EXAMPLES

[0080] FIG. 11 is a configuration diagram of the light guide plate 130 of this embodiment. This is an optical configuration in which a light beam from a light source is two-dimensionally replicated and emitted to a pupil SP. 131a is an incident portion, 131b is a first light replicating portion, and 131c is a second light replicating portion. A light beam from a light source enters the incident portion 131a and propagates through the light guide plate 131 by total reflection, and is separated into multiple light beams in the y direction by the first light replicating portion 131b. The first light replicating portion 131b is composed of multiple half mirrors that reflect a part of the light beam. The light beam replicated by the first light replicating portion 131b enters the second light replicating portion 131c, is separated into multiple light beams in the x direction, and is emitted to the pupil SP. The second light replicating portion 131c corresponds to the multiple separation surfaces 32c of the first embodiment. The first light replicating portion 131b may be composed of a diffraction element, a metasurface, a holographic element, or the like.

[0081] The disclosure of this embodiment includes the following configuration. (Configuration 1) The separator has a first surface and a second surface which are parallel to each other, and a first to a third separation surface which are inclined with respect to the first surface, The angle [°] of each separation surface with respect to the normal line of the first surface is ψ, and the incident angle [°] of the nth (n: natural number) light ray incident on the first surface is θ n (θ 1 +5<θ 2 <θ 3 -5), the incidence angle is 90-θ n The reflectance of the mth (m: 1, 2, 3) separation surface for the light of the dominant wavelength incident at +ψ[°] is Rs1 mn When Rs1 21 >Rs1 22 >Rs1 23 Rs1 31 <Rs1 32 Rs1 31 <Rs1 32 A light guide plate characterized by satisfying the following conditional expressions: (Configuration 2) Incident angle is 90-θ n The reflectance of the mth separation surface for the light of the dominant wavelength incident at -ψ [°] is Rs2 mn When Rs2 m3 <0.05 2. The light guide plate according to configuration 1, which satisfies the following conditional expression: (Configuration 3) The reflectance of the first separation surface is Rs1 11 >Rs1 12 >Rs1 13 3. The light guide plate according to configuration 1 or 2, which satisfies the following conditional expression: (Configuration 4) Incident angle is 90-θ n The reflectance of the mth separation surface for the light of the dominant wavelength incident at +ψ [°] and the incident angle of 90-θ n The reflectance of the mth separation surface for light of the dominant wavelength incident at −ψ [°] is the reflectance of S-polarized light, Incident angle is 90-θ n The reflectance of the mth separation surface for the P-polarized light of the dominant wavelength incident at +ψ[°] is Rp1 mn When Rs1 22 >2×Rp1 22 4. The light guide plate according to any one of configurations 1 to 3, which satisfies the following conditional expression: (Configuration 5) the first to third separation surfaces are formed of a plurality of dielectric films, On the second separation surface, of the first and second films having a total thickness of 1st and 2nd films, the film having a higher refractive index for the light of the dominant wavelength is designated as the first film, and the film having a lower refractive index is designated as the second film, and the refractive index of the first film is n H , the refractive index of the second film is n L The refractive index of the light guide plate with respect to the light of the dominant wavelength is n G When

[0082]

number

[0083] 6. The light guide plate according to any one of configurations 1 to 5, which satisfies the following conditional expression: (Configuration 6) The total thickness of the first film is M H [nm], the total thickness of the second film is M H When [nm] is used, M H >400 M L >300 6. The light guide plate according to configuration 5, which satisfies the following condition: (Configuration 7) 7. The light guide plate according to configuration 5 or 6, wherein the number of film layers on the second separation surface is 20 or more. (Configuration 8) A light guide plate according to any one of configurations 1 to 7; a light source that emits a light beam of a predetermined polarized light incident on the light guide plate. (Configuration 9) When the central wavelength of at least one spectrum of the light beam emitted from the light source is R [nm] and the half width of the spectrum is W [nm], 0.00 <W / R<0.03 9. The image display device according to configuration 8, wherein the following condition is satisfied:

[0084] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0085] 32 Light guide plate 32a 1st page 32b 2nd side 32c separation plane

Claims

1. The substrate has a first surface and a second surface which are parallel to each other, and first to third separation surfaces which are inclined with respect to the first surface, The angle [°] of each separation surface with respect to the normal line of the first surface is ψ, and the incident angle [°] of the nth light ray (n: natural number) incident on the first surface is θ ｎ (θ １ +5<θ ２ <θ ３ -5), the incidence angle is 90-θ ｎ The reflectance of the mth (m: 1, 2, 3) separation surface for the light of the dominant wavelength incident at +ψ [°] is Rs1 ｍｎ When Rs1 ２１ >Rs1 ２２ >Rs1 ２３ Rs1 ３１ <Rs1 ３２ Rs1 ３１ <Rs1 ３２ A light guide plate characterized by satisfying the following conditional expressions:

2. Incident angle is 90-θ ｎ The reflectance of the mth separation surface for the light of the dominant wavelength incident at -ψ [°] is Rs2 ｍｎ When Rs2 ｍ３ <0.05 2. The light guide plate according to claim 1, which satisfies the following condition:

3. The reflectance of the first separation surface is Rs1 １１ >Rs1 １２ >Rs1 １３ 3. The light guide plate according to claim 1, wherein the following condition is satisfied:

4. Incident angle is 90-θ ｎ +ψ [°], and the reflectance of the mth separation surface for the light of the dominant wavelength incident at an angle of 90-θ ｎ The reflectance of the mth separation surface for light of the dominant wavelength incident at −ψ [°] is the reflectance of S-polarized light, Incident angle is 90-θ ｎ The reflectance of the mth separation surface for the P-polarized light of the dominant wavelength incident at +ψ [°] is Rp1 ｍｎ When Rs1 ２２ >2×Rp1 ２２ 3. The light guide plate according to claim 1, wherein the following condition is satisfied:

5. the first to third separation surfaces are formed of a plurality of dielectric films, On the second separation surface, of the first and second films having a total thickness of 1st and 2nd films, the film having a higher refractive index for the light of the dominant wavelength is designated as the first film, and the film having a lower refractive index is designated as the second film. The refractive index of the first film is n Ｈ , the refractive index of the second film is n Ｌ The refractive index of the light guide plate with respect to the light of the dominant wavelength is n Ｇ When [0010] 3. The light guide plate according to claim 1, wherein the following condition is satisfied:

6. The total thickness of the first film is M Ｈ [nm], the total thickness of the second film is M Ｈ When [nm], M Ｈ >400 M Ｌ >300 6. The light guide plate according to claim 5, which satisfies the following condition:

7. The light guide plate according to claim 5 , wherein the number of film layers on the second separation surface is 20 or more.

8. The light guide plate according to claim 1 or 2; a light source that emits a light beam of a predetermined polarized light incident on the light guide plate.

9. When the central wavelength of at least one spectrum of the light beam emitted from the light source is R [nm] and the half width of the spectrum is W [nm], 0.00<W / R<0.03 9. The image display device according to claim 8, wherein the following condition is satisfied:

Images