Light guide element and image display device

Abstract

To provide a light guide element that has improved light utilization efficiency.SOLUTION: A light guide element (11) guides image light from an image display element to the pupil, and has an incident unit (13) on which the image light is incident; a separation unit (14) that separates the image light in the pupil (EP) in a first direction; and an emission unit (15) that emits the image light from the light guide element. The separation unit has a plurality of separation surfaces (M1-M15) different in spectral reflectance from each other, and the plurality of separation surfaces are formed of two or more layers of dielectric films.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a light guide element and an image display device. [Background technology]

[0002] Patent Document 1 discloses an image display device that includes a light guide plate that guides a displayed image to the pupil of a viewer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-37843 Summary of the Invention [Problem to be solved by the invention]

[0004] In the image display device disclosed in Patent Document 1, there is a lot of unnecessary light, which reduces the light utilization efficiency.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a light guide element with improved light utilization efficiency. [Means for solving the problem]

[0006] A light-guiding element according to one aspect of the present invention is a light-guiding element that guides image light from an image display element to a pupil, and has an entrance section where the image light is incident, a separation section that separates the image light at the pupil in a first direction, and an exit section that emits the image light from the light-guiding element, the separation section having a plurality of separation surfaces with different spectral reflectances, and the plurality of separation surfaces being composed of a dielectric film consisting of two or more layers.

[0007] Other objects and features of the present invention are illustrated in the following examples. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a light guide element with improved light utilization efficiency. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a configuration diagram of an image display device according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating the configuration of a light guide plate according to the first embodiment. [Figure 3] FIG. 2 is a diagram illustrating the configuration of a light guide plate according to the first embodiment. [Figure 4] FIG. 2 is a configuration diagram of a light source unit in the first embodiment. [Figure 5] FIG. 2 is a configuration diagram of a light source unit in the first embodiment. [Figure 6] FIG. 10 is a diagram illustrating the configuration of a light guide plate according to a second embodiment. [Figure 7] FIG. 10 is a diagram illustrating the configuration of a light guide plate according to a third embodiment. [Figure 8] 10 is a diagram showing the reflectance of S-polarized light at the first to third exit surfaces in Example 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals, and redundant explanations will be omitted. [Example]

[0011] First, an image display device 10 and a light guide plate (light guide element) 11 according to a first embodiment of the present invention will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a configuration diagram of the image display device 10. Fig. 2 is a configuration diagram of the xy cross section of the light guide plate 11. Fig. 3 is a configuration diagram of the xz cross section of the light guide plate 11.

[0012] The image display device 10 includes a light guide plate 11 and a light source unit 12. The light guide plate 11 is made of a transparent material such as glass or plastic, and guides image light from a liquid crystal panel (image display element) 44 of the light source unit 12 to a pupil EP. The light guide plate 11 includes a first surface 11a and a second surface 11b that are parallel to each other. The light guide plate 11 also includes an entrance section 13, a separation section 14 having a plurality of separation surfaces inclined at a predetermined angle (angle θ) with respect to the y axis in the xy cross section, and an exit section 15 having a plurality of separation surfaces (exit surfaces) inclined at a predetermined angle (angle φ) in the xz cross section.

[0013] Image light is incident on the entrance unit 13. The separation unit 14 separates the image light at the pupil EP in a first direction (y direction). The separation unit 14 also has a plurality of separation surfaces with different spectral reflectances. The exit unit 15 exits the image light from the light guide plate 11.

[0014] The light guide plate 11 in this embodiment is made of a glass material with a refractive index of 1.518, for example, but is not limited to this. The multiple separation surfaces have the property of reflecting light at a predetermined angle (angle α) with a predetermined reflectance, and are composed of multiple layers (multiple dielectric films, i.e., a dielectric film consisting of two or more layers) including high-refractive-index films and low-refractive-index films. Generally, film materials such as TiO2, Ta2O5, and ZnS are used for the high-refractive-index films, and film materials such as SiO2, MgF2, and Al2O3 are used for the low-refractive-index films. To improve transmittance to the outside world, an anti-reflection film is vapor-deposited on each of the first surface 11a and the second surface 11b.

[0015] Next, light source unit 12 will be described with reference to FIG. 4. FIG. 4 is a configuration diagram of light source unit 12. Light source unit 12 includes RGB laser light sources 41 (41R, 41G, 41B), a cross dichroic prism 42, an illumination optical system 43, a liquid crystal panel (image display element) 44, and a condenser lens 45. RGB laser light (P polarized light) emitted from laser light source 41 is combined by cross dichroic prism 42 and emitted to illumination optical system 43. The laser light incident on illumination optical system 43 uniformly illuminates liquid crystal panel 44. Image light (S polarized light) modulated by liquid crystal panel 44 is condensed at a predetermined position on light guide plate 11 via condenser lens 45. Light (P polarized light) not modulated by liquid crystal panel 44 is absorbed by a polarizing plate (not shown) or the like.

[0016] The P-polarized light and the S-polarized light correspond to the polarization directions defined by the separation surface (exit surface) of the exit section 15 of the light guide plate 11. In this embodiment, the wavelength of the laser light source 41B is 450 nm, the wavelength of the laser light source 41G is 520 nm, and the wavelength of the laser light source 41R is 640 nm. The dominant wavelength of the laser light source 41 is 520 nm, which has a high relative luminosity factor. Note that the image display device 10 of this embodiment is configured to emit light of three colors, RGB, but is not limited to this. For example, it may be configured to emit monochromatic light using only the laser light source 41G.

[0017] In this embodiment, instead of the liquid crystal panel 44, a reflective liquid crystal panel (LCOS) or a digital mirror device in which pixels are formed by tiny mirrors may be used as the image display element. The light source unit 12 may also be configured using a laser light source and a MEMS (Micro Electro Mechanical Systems). Alternatively, the light source unit 12 may be an OLED (Organic Light Emitting Diode) or a MicroLED.

[0018] Image light polarized in a predetermined direction (S-polarized light) emitted from light source unit 12 enters entrance section 13 of light guide plate 11, is deflected in a predetermined direction by reflecting surface 13a, and is totally reflected by first surface 11a and second surface 11b to propagate through light guide plate 11. The image light is then split into multiple light beams in the xy cross section by splitting section 14 (the eyebox of the observer's pupil EP in the y direction is enlarged) and guided to exit section 15.

[0019] In this embodiment, the angle of the image light incident on the reflecting surface 13a of the incident unit 13 is assumed to be ±10° (angle within the glass). In FIG. 2, ray L22 represents the chief ray in the xy cross section, ray L21 represents the chief ray at +10° to the chief ray, and ray L23 represents the chief ray at -10° to the chief ray, and the angle γ of ray L22 with respect to the y axis is 40° (γ=40°). In FIG. 3, ray L32 represents the chief ray in the xz cross section, ray L31 represents the chief ray at +10° to the chief ray, and ray L33 represents the chief ray at -10° to the chief ray. The separation unit 14 is configured with multiple separation surfaces (15 separation surfaces) inclined at an angle θ. Multiple dielectric films M1 to 15 are formed on the multiple separation surfaces, respectively. In this embodiment, θ=20°. However, in this embodiment, the number of dielectric films (separation surfaces) is not limited to 15, and may be any other number.

[0020] The image light guided to the exit unit 15 is split into multiple light beams in the xz cross section (the eyebox in the second direction (x direction) of the observer's pupil EP is enlarged) and guided to the observer's pupil EP. The exit unit 15 is composed of multiple (12) separation surfaces (exit surfaces) inclined at a predetermined angle φ. The exit unit 15 has multiple exit surfaces with different spectral reflectances. Multiple dielectric films M21 to M32 are formed on each of the multiple exit surfaces. In this embodiment, φ = 30°. However, in this embodiment, the number of dielectric films (exit surfaces) is not limited to 12 and may be other numbers. The incident angles of the light beams L31, L32, and L33 reflected by the reflecting surface 13a of the entrance unit 13 with respect to the second surface 11b of the light guide plate 11 in the xz cross section are 70°, 60°, and 50°, respectively. The entrance unit 13 may be composed of a diffraction element, a metasurface, a holographic element, or the like.

[0021] Numerical Example 1 shows the reflectance (%) of S-polarized light and P-polarized light for the dielectric films M1-15 of the separator 14 at wavelengths of 450 nm, 520 nm, and 640 nm versus the incident angle of the film. Blank spaces indicate any reflectance. In this example, the dielectric films M1-15 are designed so that the reflectance of S-polarized light and the reflectance of P-polarized light are approximately equal. It should be noted that because light rays L21-L23 propagate while undergoing total internal reflection, the incident angle (°) of the dielectric film on the xy cross section does not coincide with the incident angle (°) of the dielectric film. For example, when light ray L32 (principal ray on the xz cross section) is incident at incident angles of 60°, 70°, and 80° on the xy cross section of the dielectric film, the incident angles of the dielectric film are 64.3°, 72.8°, and 81.4°, respectively.

[0022] The reason for matching the reflectance of S-polarized light and P-polarized light is explained below. The light beam from the incident unit 13 propagates through the light guide plate 11 while being totally reflected by the first surface 11a and the second surface 11b. Therefore, the relationship between P-polarized light and S-polarized light in the separation unit 14 changes depending on whether the light is incident on the dielectric film from the first surface 11a or the second surface 11b. Therefore, it is preferable to have S-polarized light incident on the separation surface of the exit unit 15. If the reflectance of P-polarized light is significantly lower than that of S-polarized light, the amount of image light emitted from the separation unit 14 decreases. On the other hand, if the reflectance of P-polarized light is significantly higher than that of S-polarized light, the amount of P-polarized light, which is unwanted light, increases in the image light emitted from the separation unit 14, resulting in increased unwanted light such as ghosts.

[0023] Light ray L21 (film incident angle 64.3°) is split into multiple light rays by the first to fifth dielectric films M1 to M5. Similarly, light ray L22 (film incident angle 72.8°) is split into multiple light rays by the sixth to tenth dielectric films M6 to M10, and light ray L23 (film incident angle 81.4°) is split into multiple light rays by the eleventh to fifteenth dielectric films M11 to M15. The multiple split light rays are guided to the exit portion 15 and then to the pupil EP. Therefore, the light flux in the y direction of the pupil EP can be condensed, thereby achieving high light utilization efficiency. In the case of a film incident angle of 72.8°, the light intensity distribution in the y direction within the pupil EP can be made uniform by increasing the reflectivity from the sixth dielectric film M6 to the tenth dielectric film M10.

[0024] Figures 5(a) and (b) show a design example of the dielectric film M6. The dielectric film M6 is an alternating film of high-refractive index TiO2 films and low-refractive index SiO2 films, with 34 film layers. The total SiO2 film thickness is 1250 nm, and the total TiO2 film thickness is 1190 nm. At a dominant wavelength of 520 nm for green (G) light and a dominant wavelength of 640 nm for red (R) light, the reflectance of S-polarized light and the reflectance of P-polarized light at angles of incidence on the film between 72.8° and 79.6° are approximately the same and are tilted at a predetermined reflectance. Blue (B) light with a dominant wavelength of 450 nm exhibits similar characteristics. The other dielectric films are also composed of alternating films of high-refractive index TiO2 films and low-refractive index SiO2 films.

[0025] The image light (S-polarized light) emitted from the separation unit 14 is totally reflected and propagates through the light guide plate 11, then split into multiple light beams at the emission unit 15 and directed to the viewer's pupil EP. The emission unit 15 is composed of 21st to 32nd dielectric films M21 to M32. Like the separation unit 14, the dielectric films M21 to M32 are composed of alternating high-refractive-index films of TiO2 and low-refractive-index films of SiO2. Numerical Example 2 shows the reflectance (%) of S-polarized light versus the incident angle of the dielectric films M21 to M32 of the separation unit 14 at dominant wavelengths of 450 nm, 520 nm, and 640 nm. Any reflectance can be used in the blank cells.

[0026] The first light ray L31 (incident angle 70°) is split into multiple light rays by the 21st to 26th dielectric films M21 to M26 and is directed to the pupil EP. The second light ray L32 (incident angle 60°) passes through the 21st to 23rd dielectric films M21 to M23, is split into multiple light rays by the 24th to 30th dielectric films M24 to M29 and is directed to the pupil EP. The third light ray L33 (incident angle 50°) passes through the 21st to 26th dielectric films M21 to M26, is split into multiple light rays by the 27th to 32nd dielectric films M27 to M33 and is directed to the pupil EP. Therefore, the light beam can be focused on the pupil EP, thereby achieving high light utilization efficiency.

[0027] The field of view angle [°] in the first direction (y direction, vertical direction) at the pupil EP is defined as ωV, and the field of view angle [°] in the second direction (x direction, horizontal direction) is defined as ωH. The position of the pupil EP is the position of the eye relief, and is generally placed at a position 10 mm to 30 mm from the exit portion of the light guide plate 11. In this embodiment, the eye relief is 20 mm. If the eye relief value is stated in the specifications, the value in the specifications can be used.

[0028] In this embodiment, a mask with an opening of 2 mm x 2 mm is placed at the position of the eye relief (20 mm in this embodiment), and the range into which all light rays with a field of view ωV in the first direction are incident is defined as the size of the eyebox in the first direction. Similarly, the range into which all light rays with a field of view ωH in the second direction are incident is defined as the size of the eyebox in the second direction. If the eyebox value is listed in the specifications, the value in the specifications can also be used.

[0029] The preferred conditions for this example will now be described.

[0030] It is preferable that the angle θ (absolute value) (°) of the separator 14 with respect to the y direction satisfies the following conditional expression (1).

[0031] 5≦θ≦35 (1) If the lower limit of conditional expression (1) is exceeded, the dielectric film becomes approximately parallel to the y-axis, making it difficult to separate the light beams. On the other hand, if the upper limit of conditional expression (1) is exceeded, the difference in angle on the yz cross section becomes a large difference in the angle of incidence on the film, making it difficult to achieve the desired performance.

[0032] More preferably, the numerical range of conditional expression (1) is set as in the following conditional expression (1a).

[0033] 7≦θ≦30 (1a) More preferably, the numerical range of conditional expression (1) is set as in the following conditional expression (1b).

[0034] 10≦θ≦25 (1b) When the refractive index of the dielectric film having the highest refractive index in light of the dominant wavelength is nH and the refractive index of the dielectric film having the lowest refractive index is nL, it is preferable that the following conditional expression (2) be satisfied.

[0035] nH≧2.00, nL≦1.60 (2) To obtain the desired performance, a refractive index difference between the high refractive index film and the low refractive index film is required.

[0036] More preferably, the numerical range of conditional expression (2) is set as in the following conditional expression (2a).

[0037] nH≧2.10, nL≦1.55 (2a) is.

[0038] More preferably, the numerical range of conditional expression (2) is set as in the following conditional expression (2b).

[0039] nH≧2.20, nL≦1.50 (2b) The separation unit 14 has a first separation surface (M3), a second separation surface (M8), and a third separation surface (M13) as a plurality of separation surfaces. However, in this embodiment, the first to third separation surfaces are not limited to the dielectric films M3, M8, and M13, and may be any dielectric films arranged in order from closest to the incident unit 13.

[0040] Of the multiple separation surfaces, the nth (n=1, 2, 3) separation surface from the entrance portion 13 is referred to as the nth separation surface, the total film thickness [nm] of separation surfaces having a refractive index of 2.0 or more for light of the dominant wavelength is referred to as Hn, and the total film thickness [nm] of separation surfaces having a refractive index of 1.6 or less for light of the dominant wavelength is referred to as Ln. In this case, it is preferable that the multiple separation surfaces include at least one separation surface that satisfies the following conditional expression (3):

[0041] Hn≧100, Ln≧100 (3) To obtain the desired performance, a plurality of high refractive index films and low refractive index films each having a predetermined thickness or more are required.

[0042] In this embodiment, it is preferable to satisfy the following conditional expression (4).

[0043] H2≧100, L2≧100 (4) More preferably, the numerical range of conditional expression (4) is set as in the following conditional expression (4a).

[0044] H2≧400, L2≧400 (4a) More preferably, the numerical range of conditional expression (4) is set as in the following conditional expression (4b).

[0045] H2≧700, L2≧700 (4b) In this embodiment, it is preferable to satisfy the following conditional expressions (5) and (6).

[0046] H1≧100, L1≧100 (5) H3≧100, L3≧100 (6) More preferably, the numerical range of at least one of conditional expressions (5) and (6) is set as shown in the following conditional expressions (5a) and (6a), respectively.

[0047] H1≧400, L1≧400 (5a) H3≧400, L3≧400 (6a) More preferably, the numerical range of at least one of conditional expressions (5) and (6) is set as shown in the following conditional expressions (5a) and (6a), respectively.

[0048] H1≧700, L1≧700 (5b) H3≧700, L3≧700 (6b) To achieve the desired performance, the number of membrane layers on the second separation surface (M8) is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more.

[0049] The angle of incidence [°] of the chief ray on the nth separation surface is α, the reflectance [%] of the nth separation surface for S-polarized light of the dominant wavelength is Re(α, n, S), and the reflectance [%] of the nth separation surface for P-polarized light is Re(α, n, P). In this case, it is preferable that the multiple separation surfaces include at least one separation surface that satisfies the following conditional expression (7):

[0050] 0.7≦Re(α, n, P) / Re(α, n, S)≦1.6 (7) If the lower limit of condition (7) is exceeded, the amount of light decreases, which is undesirable, whereas if the upper limit of condition (7) is exceeded, unwanted light such as ghosts increases, which is undesirable.

[0051] In this embodiment, it is preferable to satisfy the following conditional expression (8).

[0052] 0.7≦Re(α, 2, P) / Re(α, 2, S)≦1.6 (8) More preferably, the numerical range of conditional expression (8) is set as in the following conditional expression (8a).

[0053] 0.8≦Re(α, 2, P) / Re(α, 2, S)≦1.4 (8a) More preferably, the numerical range of conditional expression (8) is set as in the following conditional expression (8b).

[0054] 0.9≦Re(α, 2, P) / Re(α, 2, S)≦1.2 (8b) In this embodiment, it is preferable to satisfy at least one of the following conditional expressions (9) and (10).

[0055] 0.7≦Re(α, 1, P) / Re(α, 1, S)≦1.6 (9) 0.7≦Re(α, 3, P) / Re(α, 3, S)≦1.6 (10) More preferably, the numerical range of at least one of the conditional expressions (9) and (10) is set as in the following conditional expressions (9a) and (10a), respectively.

[0056] 0.8≦Re(α, 1, P) / Re(α, 1, S)≦1.4 (9a) 0.8≦Re(α, 3, P) / Re(α, 3, S)≦1.4 (10a) More preferably, the numerical range of at least one of the conditional expressions (9) and (10) is set as shown in the following conditional expressions (9b) and (10b), respectively.

[0057] 0.9≦Re(α, 1, P) / Re(α, 1, S)≦1.2 (9b) 0.9≦Re(α, 3, P) / Re(α, 3, S)≦1.2 (10b) The exit unit 15 has a plurality of exit surfaces, namely, a first exit surface (M23), a second exit surface (M26), and a third exit surface (M30). However, in this embodiment, the first to third exit surfaces are not limited to the dielectric films M23, M26, and M30, and may be any dielectric films arranged in order from closest to the incident unit 13. The mth (m = 1, 2, 3) exit surface from the incident unit 13 among the plurality of exit surfaces is designated as the mth exit surface. The angle of incidence [°] of the chief ray onto the mth exit surface is designated as β, the reflectance [%] of the S-polarized light at the mth exit surface for light of the dominant wavelength is designated as Ro(β, m, S), and the reflectance [%] of the P-polarized light at the mth exit surface is designated as Ro(β, m, P). In this case, it is preferable that the plurality of exit surfaces include at least one exit surface that satisfies the following conditional expression (11):

[0058] Ro(β, m, P) / Ro(β, m, S)≦0.3 (11) If the upper limit of conditional expression (11) is exceeded, the transmittance of the outside world decreases, making it difficult to achieve the desired quality, which is undesirable.

[0059] In this embodiment, it is preferable to satisfy the following conditional expression (12).

[0060] Ro(β, 2, P) / Ro(β, 2, S)≦0.3 (12) More preferably, the numerical range of conditional expression (12) is set as in the following conditional expression (12a).

[0061] Ro(β, 2, P) / Ro(β, 2, S)≦0.2 (12a) More preferably, the numerical range of conditional expression (12) is set as in the following conditional expression (12b).

[0062] Ro(β, 2, P) / Ro(β, 2, S)≦0.1 (12b) In this embodiment, it is preferable to satisfy at least one of the following conditional expressions (13) and (14).

[0063] Ro(β, 1, P) / Ro(β, 1, S)≦0.3 (13) Ro(β, 3, P) / Ro(β, 3, S)≦0.3 (14) More preferably, the numerical range of at least one of the conditional expressions (13) and (14) is set as shown in the following conditional expressions (13a) and (14a), respectively.

[0064] Ro(β, 1, P) / Ro(β, 1, S)≦0.2 (13a) Ro(β, 3, P) / Ro(β, 3, S)≦0.2 (14a) More preferably, the numerical range of at least one of the conditional expressions (13) and (14) is set as shown in the following conditional expressions (13b) and (14b), respectively.

[0065] Ro(β, 1, P) / Ro(β, 1, S)≦0.1 (13b) Ro(β, 3, P) / Ro(β, 3, S)≦0.1 (14b) When the refractive index of the light guide plate 11 is nG, the plurality of separation surfaces preferably include at least one separation surface that satisfies the following conditional expressions (15) and (16).

[0066] Re(α+ωV / nG, 1, P)>1.1×Re(α, 1, P) (15) Re(α, n, P)>1.1×Re(α-ωV / nG, n, P) (16) If the conditions (15) and (16) are not satisfied, the image light cannot be focused on the desired eye box, and the light utilization efficiency decreases, which is undesirable.

[0067] In this embodiment, it is preferable to satisfy the following conditional expression (17):

[0068] Re(α+ωV / nG, 1, P)>1.1×Re(α, 1, P) (17) More preferably, the numerical range of conditional expression (17) is set as in the following conditional expression (17a).

[0069] Re(α+ωV / nG, 1, P)>1.5×Re(α, 1, P) (17a) More preferably, the numerical range of conditional expression (17) is set as in the following conditional expression (17b).

[0070] Re(α+ωV / nG, 1, P)>2.0×Re(α, 1, P) (17b) In this embodiment, it is preferable to satisfy the following conditional expression (18).

[0071] Re(α, 2, P)>1.1×Re(α-ωV / nG, 2, P) (18) More preferably, the numerical range of conditional expression (18) is set as in the following conditional expression (18a).

[0072] Re(α, 2, P)>1.5×Re(α-ωV / nG, 2, P) (18a) More preferably, the numerical range of conditional expression (18) is set as in the following conditional expression (18b).

[0073] Re(α, 2, P)>2.0×Re(α-ωV / nG, 2, P) (18b) In this embodiment, the field of view of the pupil EP is preferably 30° or more. The light-collecting effect of this embodiment is particularly effective in image display devices with large field of view, which significantly reduces light utilization efficiency. More preferably, the field of view is 35° or more. Even more preferably, the field of view is 40° or more.

[0074] When the distribution of the eyebox illuminance [lx] is divided into five equal parts in the y direction, the maximum value of the average illuminance is LVH and the minimum value is LVL, it is preferable to satisfy the following conditional expression (19):

[0075] LVH / LVL≦2.5 (19) If conditional expression (19) is deviated from, the illuminance becomes significantly uneven, making it difficult to obtain the desired image quality, which is undesirable.

[0076] More preferably, the numerical range of conditional expression (19) is set as in the following conditional expression (19a).

[0077] LVH / LVL≦2.0 (19a) More preferably, the numerical range of conditional expression (19) is set as in the following conditional expression (19b).

[0078] LVH / LVL≦1.6 (19b) When the illuminance [lx] of the dominant wavelength incident on the incident portion 13 is Li and the illuminance emitted into the eye box region in the y direction (the width in the x direction is not specified) is Ly [lx], it is preferable to satisfy the following conditional expression (20):

[0079] Ly / Li≧0.40 (20) If conditional expression (20) is deviated from, the desired light utilization efficiency cannot be obtained, resulting in a dark image display device, which is undesirable.

[0080] More preferably, the numerical range of conditional expression (20) is set as in the following conditional expression (20a):

[0081] Ly / Li≧0.50 (20a) More preferably, the numerical range of conditional expression (20) is set as in the following conditional expression (20b).

[0082] Ly / Li≧0.60 (20b) When the illuminance of polarized light in the first direction (P polarized light) emitted into the eyebox area in the y direction (the width in the x direction is not specified) is Ly1 [lx] and the illuminance of polarized light in the second direction (S polarized light) is Ly2 [lx], it is preferable to satisfy the following conditional expression (21):

[0083] |Ly1−Ly2| / (Ly1+Ly2)≧0.5 (21) If condition (21) is deviated from, the amount of unwanted light increases, resulting in an increase in unwanted light such as ghosts.

[0084] More preferably, the numerical range of conditional expression (21) is set as in the following conditional expression (21a).

[0085] |Ly1−Ly2| / (Ly1+Ly2)≧0.65 (21a) More preferably, the numerical range of conditional expression (21) is set as in the following conditional expression (21b).

[0086] |Ly1−Ly2| / (Ly1+Ly2)≧0.80 (21b) The light source unit 12 emits image light of RGB visible light. The peak wavelength in the wavelength range of 500 nm to 580 nm (red band) is defined as the first wavelength, the peak wavelength in the wavelength range of 590 nm to 670 nm (green band) is defined as the second wavelength, and the peak wavelength in the wavelength range of 430 nm to 490 nm (blue band) is defined as the third wavelength. The amount of light of the first wavelength [W / mm 2 ] is defined as Ei1, the amount of light of the second wavelength as Ei2, and the amount of light of the third wavelength as Ei3. Furthermore, the amount of light of the first wavelength emitted into the eye box region in the y direction is defined as Ey1, the amount of light of the second wavelength as Ey2, and the amount of light of the third wavelength as Ey3. In this case, it is preferable to satisfy the following conditional expressions (22) to (24).

[0087] Ey1 / Ei1≧0.40 (22) Ey2 / Ei2≧0.40 (23) Ey3 / Ei3≧0.40 (24) More preferably, the numerical ranges of conditional expressions (22) to (24) are set as shown in the following conditional expressions (22a) to (24a), respectively.

[0088] Ey1 / Ei1≧0.50 (22a) Ey2 / Ei2≧0.50 (23a) Ey3 / Ei3≧0.50 (24a) More preferably, the numerical ranges of conditional expressions (22) to (24) are set as shown in the following conditional expressions (22b) to (24b), respectively.

[0089] Ey1 / Ei1≧0.60 (22b) Ey2 / Ei2≧0.60 (23b) Ey3 / Ei3≧0.60 (24b) When the illuminance [lx] emitted into the eyebox region in the x direction (the width in the y direction is not specified) is Lx, it is preferable to satisfy the following conditional expression (25):

[0090] Lx / Li≧0.40 (25) If conditional expression (24) is deviated from, the desired light utilization efficiency cannot be obtained, resulting in a dark image display device, which is undesirable.

[0091] More preferably, the numerical range of conditional expression (25) is set as in the following conditional expression (25a):

[0092] Lx / Li≧0.50 (25a) More preferably, the numerical range of conditional expression (25) is set as in the following conditional expression (25b).

[0093] Lx / Li≧0.60 (25b) The amount of light of the first wavelength emitted into the eye box area in the x direction [W / mm 2 ] is Ex1, and the light intensity of the second wavelength [W / mm2 ] to Ex2, the light intensity of the third wavelength [W / mm 2 In this case, it is preferable that the following conditional expressions (26) to (28) be satisfied.

[0094] Ex1 / Ei1≧0.40 (26) Ex2 / Ei2≧0.40 (27) Ex3 / Ei3≧0.40 (28) More preferably, the numerical ranges of conditional expressions (26) to (28) are set as shown in the following conditional expressions (26a) to (28a), respectively.

[0095] Ex1 / Ei1≧0.50 (26a) Ex2 / Ei2≧0.50 (27a) Ex3 / Ei3≧0.50 (28a) More preferably, the numerical ranges of conditional expressions (26) to (28) are set as shown in the following conditional expressions (26b) to (28b), respectively.

[0096] Ex1 / Ei1≧0.60 (26b) Ex2 / Ei2 ≥ 0.60 (27b) Ex3 / Ei3≧0.60 (28b) When the average maximum reflectance of the P-polarized light and the S-polarized light of the separating unit 14 in the principal ray of the dominant wavelength is Rmax and the average minimum reflectance of the P-polarized light and the S-polarized light is Rmin, it is preferable to satisfy the following conditional expression (29):

[0097] Rmin / Rmax≦0.20 (29) More preferably, the numerical range of conditional expression (29) is set as in the following conditional expression (29a):

[0098] Rmin / Rmax≦0.15 (29a) More preferably, the numerical range of conditional expression (29) is set as in the following conditional expression (29b).

[0099] Rmin / Rmax≦0.10 (29b) In this embodiment, the plurality of separation surfaces includes at least one separation surface that satisfies the following conditional expressions (30) and (31).

[0100] Re(α, n, P)≦10.0 (30) Re(α, n, S)≦10.0 (31) Any deviation from conditions (30) and (31) is undesirable because it increases the amount of unnecessary light that illuminates outside the eyebox.

[0101] It is preferable that the first separation surface (M3) satisfies the following conditional expressions (32) and (33).

[0102] Re(α, 1, P)≦10.0 (32) Re(α, 1, S)≦10.0 (33) More preferably, the numerical ranges of the conditional expressions (32) and (33) are set as shown in the following conditional expressions (32a) and (33a), respectively.

[0103] Re(α, 1, P) ≤ 7.0 (32a) Re(α, 1, S) ≤ 7.0 (33a) More preferably, the numerical ranges of the conditional expressions (32) and (33) are set as shown in the following conditional expressions (32b) and (33b), respectively.

[0104] Re(α, 1, P)≦4.0 (32b) Re(α, 1, S)≦4.0 (33b) When designing a dielectric film, it is preferable to satisfy the following conditional formula (34), where R is the central wavelength [nm] of at least one spectrum of a light beam emitted from a light source, and W is the half-width [nm] of the spectrum:

[0105] 0.00 <W / R<0.03 (34) In this embodiment, the central wavelength R is 450 nm, 520 nm, or 640 nm, which are the dominant wavelengths of the laser light source 41. If the upper limit of conditional formula (34) is exceeded, it becomes necessary to achieve a predetermined reflectance over a wide wavelength range, which makes film design difficult, resulting in a decrease in light utilization efficiency and uneven brightness.

[0106] More preferably, the numerical range of conditional expression (34) is set as in the following conditional expression (34a):

[0107] 0.00 <W / R<0.02 (34a) More preferably, the numerical range of conditional expression (34) is set as in the following conditional expression (34b).

[0108] 0.000 <W / R<0.015 (34b) In this embodiment, it is preferable to configure the injection section 15 as follows.

[0109] For example, in Fig. 3, the rays with incident angles θ1, θ2, θ3 (θ1+5<θ2<θ3-5) on the first surface 32a are designated as the first ray L31, the second ray L32, and the third ray L33, respectively. If the angle [°] of each separation surface with respect to the normal to the first surface 11a (second surface 11b) is designated as φ, then the incident angle φ1 of the qth ray (q: natural number) from the first surface 11a to the separation surface (exit surface) is n [°] is 90-θ q +φ. In addition, the incident angle of the qth ray from the second surface 11b to the separation surface (exit surface) is φ2 q [°] is 90-θ q For example, the angle φ is 30°, the incident angles θ1, θ2, and θ3 are 50°, 60°, and 70°, respectively, and the incident angles φ11, φ12, φ13, φ21, φ22, and φ23 are 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 11.

[0110] The first light ray L31 is split into multiple light rays by, for example, the 21st to 27th dielectric films M21 to 27 and is guided to the pupil EP. The second light ray L32 passes through the 21st to 23rd dielectric films M21 to M23, is split into multiple light rays by the 24th to 30th dielectric films M24 to M30 and is guided to the pupil EP. The third light ray L33 passes through the 21st to 26th dielectric films M21 to M26, is split into multiple light rays by the 27th to 33rd dielectric films M27 to M32 and is guided to the pupil EP. Therefore, the light beam can be focused on the pupil EP, thereby achieving high light utilization efficiency.

[0111] The 24th dielectric film M24 is defined as the first exit surface, the 24th dielectric film M27 as the second exit surface, and the 30th dielectric film M30 as the third exit surface. If the eyebox size is d (mm), the surface that passes through or is closest to the normal from the center of the eyebox is defined as the second exit surface. Also, the surface that passes through or is closest to the normal from a position d / 2 from the center of the eyebox in the negative x direction is defined as the first exit surface, and the surface that passes through or is closest to the normal from a position d / 2 from the center of the eyebox in the positive x direction is defined as the third exit surface. Figure 8 is a diagram showing the reflectance of S-polarized light versus the incident angle of light of the dominant wavelength on the first to third exit surfaces. The qth ray (incident angle φ1 q ) the reflectivity of S-polarized light at the pth (p: 1, 2, 3) exit surface is Rs1 pq In this case, it is preferable that the first to third exit surfaces satisfy the following conditional expressions (35) to (37).

[0112] Rs1 21 >Rs1 22 >Rs1 23 (35) Rs1 31 <Rs1 32 (36) Rs1 33 <Rs1 32 (37) If conditional expression (35) is not satisfied, brightness unevenness will be large, and if conditional expressions (36) and (37) are not satisfied, the transmittance of external light will increase.

[0113] More preferably, the first to third exit surfaces satisfy the following conditional expressions (35a) to (37a).

[0114] Rs1 21 >1.2×Rs1 22 >1.2×Rs1 23 (35a) 1.2 x Rs1 31 <Rs1 32 (36a) 1.2 x Rs1 33 <Rs1 32 (37a) It is more preferable that the first to third exit surfaces satisfy the following conditional expressions (35b) to (37b).

[0115] Rs1 21 >1.4×Rs1 22 >1.4×Rs1 23 (35b) 1.4 x Rs1 31 <Rs1 32 (36b) 1.4 x Rs1 33 <Rs1 32 (37b) Since the 21st to 33rd dielectric films M21 to M33 have film properties that combine the properties of a polarization separation film and a half mirror film, it is preferable that the refractive index nG of the substrate be low in order to separate polarization at an incident angle ψ12 of 60°. Specifically, it is preferable that the following conditional expression (38) be satisfied:

[0116] nG≦1.70 (38) If the upper limit of conditional expression (38) is exceeded, the Brewster condition cannot be satisfied, and the transmittance of external light drops significantly.

[0117] It is more preferable to satisfy the following conditional expression (38a):

[0118] nG≦1.65 (38a) It is more preferable that the following conditional expression (38b) be satisfied:

[0119] nG≦1.60 (38b) Numerical Example 3 and Numerical Example 4 are other numerical examples of the separation unit 14 in this embodiment. Numerical Example 3 is a numerical example in which the number of types of dielectric films is reduced from 15 to 8. Numerical Example 4 is a numerical example in which the illuminance distribution is made more uniform. Numerical Example 3 shows a configuration in which the same dielectric film is arranged on every two separation surfaces, but this is not limited to this, and a configuration in which the same dielectric film is arranged on every three or four separation surfaces may also be used.

[0120] In this embodiment, the separation surface between the separation section 14 and the emission section 15 is configured with a dielectric film formed thereon, but it may also be configured with a structure composed of a microstructure such as a metasurface, a holographic element, or the like. [Example]

[0121] Next, a light guide plate 61 according to a second embodiment of the present invention will be described with reference to Fig. 6. Fig. 6 is a structural diagram of the light guide plate 61 according to this embodiment. The light guide plate 61 includes an incident portion 63, a separation portion 64 having a plurality of separation surfaces inclined at a predetermined angle in the xy cross section, and an exit portion 65 having a plurality of separation surfaces inclined at a predetermined angle in the xz cross section. As in the first embodiment, first to fifteenth dielectric films M1 to M15 are deposited on the separation portion 64. The separation portion 64 has a configuration in which unnecessary separation surfaces that do not contribute to the collection of image light into the eyebox are reduced, making it possible to reduce unnecessary light and improve light utilization efficiency. [Example]

[0122] Next, a light guide plate 71 according to a third embodiment of the present invention will be described with reference to FIG. 7. FIG. 7 is a structural diagram of the light guide plate 71 according to the third embodiment. The light guide plate 71 includes an incident portion 73, a separation portion 74 having a plurality of separation surfaces inclined at a predetermined angle in the xy cross section, an exit portion 75 having a plurality of separation surfaces inclined at a predetermined angle in the xz cross section, and a reflection surface 76. As in the first embodiment, the first to fifteenth dielectric films M1 to M15 are deposited on the separation portion 74. By reflecting the image light from the incident portion 73 by the reflection surface 76, the light guide plate 71 can be made smaller. (Numerical Example 1)

[0123] [Table 1]

[0124] (Numerical Example 2)

[0125] [Table 2]

[0126] (Numerical Example 3)

[0127] [Table 3]

[0128] (Numerical Example 4)

[0129] [Table 4]

[0130] According to each embodiment, it is possible to provide a light guide element and an image display device with improved light utilization efficiency. Also, according to each embodiment, it is possible to improve the luminance distribution and reduce unevenness in the amount of light.

[0131] The disclosure of each embodiment includes the following configuration. (Configuration 1) A light guide element that guides image light from an image display element to a pupil, an incident portion onto which the image light is incident; a separation unit that separates the image light at the pupil in a first direction; an emission section that emits the image light from the light guide element, the separation unit has a plurality of separation surfaces with different spectral reflectances, A light guide element, wherein the plurality of separation surfaces are made up of a dielectric film consisting of two or more layers. (Configuration 2) When the angle [°] of the plurality of separation surfaces with respect to the first direction is θ, 5≦θ≦35 2. The light guide element according to configuration 1, wherein the following condition is satisfied: (Configuration 3) For light of the dominant wavelength, when the refractive index of the separation surface with the highest refractive index among the plurality of separation surfaces is nH and the refractive index of the separation surface with the lowest refractive index is nL, nH≧2.00, nL≦1.60 3. The light guide element according to configuration 1 or 2, wherein the following condition is satisfied: (Configuration 4) When the n-th separation surface from the incident portion among the plurality of separation surfaces is designated as the n-th separation surface, the total film thickness [nm] of the separation surfaces having a refractive index of 2.0 or more for light of the dominant wavelength is designated as Hn, and the total film thickness [nm] of the separation surfaces having a refractive index of 1.6 or less for light of the dominant wavelength is designated as Ln, The plurality of separation surfaces are Hn≧100, Ln≧100 4. The light guide element according to any one of configurations 1 to 3, comprising at least one separation surface that satisfies the following conditional expression: (Configuration 5) 5. The light guide element according to any one of configurations 1 to 4, wherein the exit portion has a plurality of exit surfaces with different spectral reflectances. (Configuration 6) A light guide element that guides image light from an image display element to a pupil, an incident portion onto which the image light is incident; a separation unit that separates the image light at the pupil in a first direction; an emission section that emits the image light from the light guide element, the separation unit has a plurality of separation surfaces with different spectral reflectances, When the n-th separation surface from the entrance portion among the plurality of separation surfaces is the n-th separation surface, the angle of incidence [°] of the chief ray on the n-th separation surface is α, the reflectance [%] of S-polarized light at the n-th separation surface for light of the dominant wavelength is Re(α, n, S), and the reflectance [%] of P-polarized light at the n-th separation surface is Re(α, n, P), The plurality of separation surfaces are 0.7≦Re(α, n, P) / Re(α, n, S)≦1.6 A light guide element comprising at least one separation surface that satisfies the following conditional expression: (Configuration 7) the emission section has a plurality of emission surfaces with different spectral reflectances, Let the m-th exit surface from the entrance portion among the plurality of exit surfaces be the m-th exit surface, the angle of incidence [°] of the chief ray onto the m-th exit surface be β, the reflectance [%] of S-polarized light at the m-th exit surface for light with a dominant wavelength be Ro(β, m, S), and the reflectance [%] of P-polarized light at the m-th exit surface be Ro(β, m, P), The plurality of exit surfaces are Ro(β, m, P) / Ro(β, m, S)≦0.3 7. The light guide element according to configuration 6, comprising at least one exit surface that satisfies the following condition: (Configuration 8) When the refractive index of the light guide element is nG and the viewing angle (°) in the first direction is ωV, The plurality of separation surfaces are Re(α+ωV / nG, 1, P)>1.1×Re(α, 1, P) Re(α, n, P)>1.1×Re(α-ωV / nG, n, P) 9. The light guide element according to configuration 7 or 8, comprising at least one separation surface that satisfies the following conditional expression: (Configuration 9) The plurality of separation surfaces are Re(α, n, P)≦10.0 Re(α, n, S)≦10.0 9. The light guide element according to any one of configurations 6 to 8, comprising at least one separation surface that satisfies the following conditional expression: (Configuration 10) When the average maximum reflectance of P-polarized light and S-polarized light in the principal ray of the dominant wavelength is Rmax, and the average minimum reflectance of the P-polarized light and the S-polarized light is Rmin, Rmin / Rmax≦0.20 10. The light guide element according to any one of configurations 1 to 9, wherein the following conditional expression is satisfied: (Configuration 11) the light guide element has a first surface and a second surface parallel to each other; the emission section has a first emission surface, a second emission surface, and a third emission surface that are inclined with respect to the first surface and have different spectral reflectances; The angle [°] of each exit surface relative to the normal of the first surface is φ, and the incident angle [°] of the qth (q: natural number) ray incident on the first surface is θ q (θ1+5<θ2<θ3-5), incident angle [°] is 90-θ q The reflectance (%) of the pth (p: 1, 2, 3) exit surface for the light of the dominant wavelength incident at +φ is Rs1 pq When Rs1 21 >Rs1 22 >Rs1 23 Rs1 31 <Rs1 32 Rs1 33 <Rs1 32 11. The light guide element according to any one of configurations 1 to 10, wherein the following conditional expression is satisfied: (Configuration 12) 12. An image display device comprising the light guide element according to any one of configurations 1 to 11 and the image display element. (Configuration 13) an image display element; a light guide element that guides image light from the image display element to a pupil, The light-guiding element is an incident portion onto which the image light is incident; a separation unit that separates the image light at the pupil in a first direction; an emission section that emits the image light from the light guide element, When the illuminance [lx] of the dominant wavelength incident on the incident portion is Li, and the amount of light [lx] emitted to the eye box region in the first direction is Ly, Ly / Li≧0.40 An image display device characterized in that the following conditional expression is satisfied: (Configuration 14) 14. The image display device according to configuration 13, wherein the separation section has a plurality of separation surfaces with different spectral reflectances. (Configuration 15) When the angle [°] of the plurality of separation surfaces with respect to the first direction is θ, 5≦θ≦35 15. The image display device according to claim 14, wherein the following condition is satisfied: (Configuration 16) Let Ly1 be the illuminance [lx] of polarized light in the first direction projected into the eyebox region in the first direction, and Ly2 be the illuminance [lx] of polarized light in the second direction. |Ly1-Ly2| / (Ly1+Ly2)≧0.5 16. The image display device according to configuration 15, wherein the following condition is satisfied: (Configuration 17) The peak wavelength in the red band is the first wavelength, the peak wavelength in the green band is the second wavelength, and the amount of light of the first wavelength incident on the incident portion [W / mm 2 ] is Ei1, the amount of light of the second wavelength incident on the incident portion [W / mm 2 ] is Ei2, the amount of light of the first wavelength [W / mm 2 ] is Ey1, and the amount of light of the second wavelength emitted into the eye box region in the first direction is Ey2, Ey1 / Ei1≧0.40 Ey2 / Ei2≧0.40 17. The image display device according to any one of configurations 13 to 16, wherein the following condition is satisfied: (Configuration 18) When the illuminance [lx] projected onto the region of the eye box in a second direction perpendicular to the first direction is Lx, Lx / Li≧0.40 18. The image display device according to any one of configurations 13 to 17, wherein the following condition is satisfied: (Configuration 19) The amount of light of the first wavelength [W / mm 2 ] is Ex1, the light intensity of the second wavelength [W / mm 2 ] is Ex2, Ex1 / Ei1≧0.40 Ex2 / Ei2≧0.40 19. The image display device according to configuration 17 or 18, wherein the following condition is satisfied: (Configuration 20) When the central wavelength [nm] of at least one spectrum of the light beam emitted from the light source is R and the half-width [nm] of said spectrum is W, 0.00 <W / R<0.03 20. The image display device according to any one of configurations 13 to 19, wherein the following condition is satisfied:

[0132] 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]

[0133] 11 Light guide plate (light guide element) 13 Input part 14 Separation section 15 Injection part M1~M15 Dielectric film (separation surface)

Claims

1. A light guide element that guides image light from an image display element to a pupil, an incident portion onto which the image light is incident; a separation unit that separates the image light at the pupil in a first direction; an emission section that emits the image light from the light guide element, the separation unit has a plurality of separation surfaces with different spectral reflectances, A light guide element, wherein the plurality of separation surfaces are formed of a dielectric film consisting of two or more layers.

2. When the angle [°] of the plurality of separation surfaces with respect to the first direction is θ, 5≦θ≦35 2. The light guide element according to claim 1, wherein the following condition is satisfied:

3. For light of the dominant wavelength, when the refractive index of the separation surface having the highest refractive index among the plurality of separation surfaces is nH and the refractive index of the separation surface having the lowest refractive index is nL, nH≧2.00, nL≦1.60 2. The light guide element according to claim 1, wherein the following condition is satisfied:

4. When the n-th separation surface from the incident portion among the plurality of separation surfaces is defined as the n-th separation surface, the total film thickness [nm] of the separation surfaces having a refractive index of 2.0 or more for light of the dominant wavelength is defined as Hn, and the total film thickness [nm] of the separation surfaces having a refractive index of 1.6 or less for light of the dominant wavelength is defined as Ln, The plurality of separation surfaces are Hn≧100, Ln≧100 2. The light guide element according to claim 1, comprising at least one separation surface that satisfies the following condition:

5. The light guide element according to claim 1 , wherein the light exit portion has a plurality of light exit surfaces with different spectral reflectances.

6. A light guide element that guides image light from an image display element to a pupil, an incident portion onto which the image light is incident; a separation unit that separates the image light at the pupil in a first direction; an emission section that emits the image light from the light guide element, the separation unit has a plurality of separation surfaces with different spectral reflectances, When the n-th separation surface from the entrance portion among the plurality of separation surfaces is the n-th separation surface, the angle of incidence [°] of the chief ray on the n-th separation surface is α, the reflectance [%] of S-polarized light at the n-th separation surface for light of the dominant wavelength is Re(α, n, S), and the reflectance [%] of P-polarized light at the n-th separation surface is Re(α, n, P), The plurality of separation surfaces are 0.7≦Re(α, n, P) / Re(α, n, S)≦1.6 A light guide element comprising at least one separation surface that satisfies the following conditional expression:

7. the emission section has a plurality of emission surfaces with different spectral reflectances, Let the m-th exit surface from the entrance portion among the plurality of exit surfaces be the m-th exit surface, let the angle of incidence [°] of the chief ray onto the m-th exit surface be β, let the reflectance [%] of S-polarized light at the m-th exit surface for light with a dominant wavelength be Ro(β, m, S), and let the reflectance [%] of P-polarized light at the m-th exit surface be Ro(β, m, P). The plurality of exit surfaces are Ro(β, m, P) / Ro(β, m, S)≦0.3 7. The light guide element according to claim 6, comprising at least one exit surface that satisfies the following condition:

8. When the refractive index of the light-guiding element is nG and the viewing angle (°) in the first direction is ωV, The plurality of separation surfaces are Re(α+ωV / nG, 1, P)>1.1×Re(α, 1, P) Re(α, n, P)>1.1×Re(α−ωV / nG, n, P) 7. The light guide element according to claim 6, comprising at least one separation surface that satisfies the following condition:

9. The plurality of separation surfaces are Re(α, n, P)≦10.0 Re(α, n, S)≦10.0 7. The light guide element according to claim 6, comprising at least one separation surface that satisfies the following condition:

10. When the average maximum reflectance of P-polarized light and S-polarized light in the principal ray of the dominant wavelength is Rmax and the average minimum reflectance of the P-polarized light and the S-polarized light is Rmin, Rmin / Rmax≦0.20 2. The light guide element according to claim 1, wherein the following condition is satisfied:

11. the light guide element has a first surface and a second surface that are parallel to each other; the emission section has a first emission surface, a second emission surface, and a third emission surface that are inclined with respect to the first surface and have different spectral reflectances; The angle [°] of each exit surface with respect to the normal to the first surface is defined as φ, and the incident angle [°] of the qth (q: natural number) ray incident on the first surface is defined as θ ｑ (θ １ +5<θ ２ <θ ３ -5), the incident angle [°] is 90-θ ｑ The reflectance (%) of the pth (p: 1, 2, 3) exit surface for the light of the dominant wavelength incident at +φ is Rs1 ｐｑ When Rs1 ２１ >Rs1 ２２ >Rs1 ２３ Rs1 ３１ <Rs1 ３２ Rs1 ３３ <Rs1 ３２ 2. The light guide element according to claim 1, wherein the following condition is satisfied:

12. An image display device comprising: the light guide element according to claim 1; and the image display element.

13. an image display element; a light guide element that guides image light from the image display element to a pupil, The light-guiding element is an incident portion onto which the image light is incident; a separation unit that separates the image light at the pupil in a first direction; an emission section that emits the image light from the light guide element, When the illuminance [lx] of the dominant wavelength incident on the incident portion is Li, and the amount of light [lx] emitted to the eye box region in the first direction is Ly, Ly / Li≧0.40 An image display device characterized in that the following conditional expression is satisfied:

14. 14. The image display device according to claim 13, wherein the separation unit has a plurality of separation surfaces with different spectral reflectances.

15. When the angle [°] of the plurality of separation surfaces with respect to the first direction is θ, 5≦θ≦35 15. The image display device according to claim 14, wherein the following condition is satisfied:

16. When the illuminance [lx] of the polarized light in the first direction emitted into the eye box region in the first direction is Ly1 and the illuminance [lx] of the polarized light in the second direction is Ly2, |Ly1−Ly2| / (Ly1+Ly2)≧0.5 16. The image display device according to claim 15, wherein the following condition is satisfied:

17. The peak wavelength in the red band is defined as a first wavelength, the peak wavelength in the green band is defined as a second wavelength, and the amount of light of the first wavelength incident on the incident portion [W / mm ２ ] is Ei1, the amount of light of the second wavelength incident on the incident portion [W / mm ２ ] is Ei2, the amount of light of the first wavelength [W / mm ２ ] is Ey1, and the amount of light of the second wavelength emitted into the eye box region in the first direction is Ey2, Ey1 / Ei1≧0.40 Ey2 / Ei2≧0.40 14. The image display device according to claim 13, wherein the following condition is satisfied:

18. When the illuminance [lx] emitted to the region of the eye box in a second direction perpendicular to the first direction is Lx, Lx / Li≧0.40 14. The image display device according to claim 13, wherein the following condition is satisfied:

19. The amount of light of the first wavelength [W / mm] emitted to the region of the eye box in a second direction perpendicular to the first direction ２ ] is Ex1, the light amount of the second wavelength [W / mm ２ ] is set to Ex2, Ex1 / Ei1≧0.40 Ex2 / Ei2≧0.40 18. The image display device according to claim 17, wherein the following condition is satisfied:

20. When the central wavelength [nm] of at least one spectrum of the light beam emitted from the light source is R and the half-width [nm] of the spectrum is W, 0.00<W / R<0.03 14. The image display device according to claim 13, wherein the following condition is satisfied:

Images