Polarization beam splitting apparatus, light source apparatus, display apparatus, and illumination system

Abstract

A polarization separation device is configured to separate light from a light source and emit a plurality of polarized light, and has a plurality of optical surfaces including a first optical surface, a second optical surface, and a third optical surface. The first optical surface is positioned closer to the incident portion of light on the polarization separation device than the second optical surface. The second optical surface is positioned closer to the incident portion than the third optical surface. It satisfies a predetermined inequality.

Description

Technology Field

[0001] The present disclosure relates to a polarization separation device, a light source device, a display device, and an illumination system. Background Technology

[0002] Japanese Patent Publication No. 2018-116261 discloses a head-mounted display (HMD) device in which a light beam from a light source is separated and emitted from a semi-transparent reflective surface. means of solving the problem

[0003] A polarization separation device according to one aspect of the present disclosure is configured to separate light from a light source and emit a plurality of polarized light. The polarization separation device has a plurality of optical surfaces including a first optical surface, a second optical surface, and a third optical surface. The first optical surface is positioned closer to the incident portion of the light on the polarization separation device than the second optical surface. The second optical surface is positioned closer to the incident portion than the third optical surface. The following inequality is satisfied:

[0004] 5≤TP1≤75

[0005] RS1≥75

[0006] At this time, TP1 is the transmittance (%) of the main wavelength of the polarized light polarized in the first direction on the first optical plane, and RS1 is the reflectance (%) of the main wavelength of the polarized light polarized in the second direction on the first optical plane. A light source device and a display device each having the above-described polarization separation device also constitute another aspect of the present disclosure.

[0007] One or more embodiments of a light source device according to one or more aspects of the present disclosure comprise a light source and a polarization separation unit configured to separate light from the light source and emit a plurality of polarized light. The polarization separation unit comprises a plurality of optical surfaces including a first optical surface, a second optical surface, and a third optical surface. The first optical surface is positioned closer to the incident portion of the light on the polarization separation unit than the second optical surface. The second optical surface is positioned closer to the incident portion than the third optical surface. The following inequality is satisfied:

[0008] 5≤TP1≤75

[0009] RS1≥75

[0010] At this time, TP1 is the transmittance (%) of the main wavelength of the polarized light polarized in the first direction on the first optical plane, and RS1 is the reflectance (%) of the main wavelength of the polarized light polarized in the second direction on the first optical plane. A display device having the light source device described above also constitutes another aspect of the present disclosure. A polarization separation device corresponding to the polarization separation part described above also constitutes another aspect of the present disclosure.

[0011] Another feature of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawings. The following description of embodiments is given by way of example. Brief explanation of the drawing

[0012] FIG. 1 is a configuration diagram of a light source device according to Example 1. FIGS. 2A, 2B, 2C, and 2D are drawings illustrating the film characteristics of the optical surface of a polarization separation device according to Example 1. FIGS. 3a and FIGS. 3b are configuration diagrams of a display device according to Example 1. FIGS. 4a and FIGS. 4b are configuration diagrams of a lighting system according to Example 1. FIG. 5 is a configuration diagram of a light source device according to Example 2. FIG. 6 is a configuration diagram of a light source device according to Example 3. FIG. 7 is a configuration diagram of a light source device according to Example 4. FIG. 8 is a configuration diagram of a light source device according to Example 5. Specific details for implementing the invention

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same reference numerals are used for identical components, and redundant descriptions are omitted.

[0014] Example 1

[0015] First, with reference to FIG. 1, a light source device (10) according to Embodiment 1 of the present disclosure will be described. FIG. 1 is a configuration diagram of a light source device (10). The light source device (10) is configured to include a light source (11), an optical system (12), a polarization separation unit (polarization separation device) (13), and a λ / 2 wavelength plate (phase plate) (14). The light source (11) is a light source such as an organic light-emitting diode (OLED), a light-emitting diode (LED), a laser, or a mercury lamp. The light beam emitted from the light source (11) passes through an optical system (12) having one or more lenses and is incident on the polarization separation unit (13). The optical system (12) is positioned between the light source (11) and the polarization separation unit (13).

[0016] The polarization separation unit (13) separates light (light beam) from a light source (11) and emits a plurality of polarized light (a plurality of light beams). The polarization separation unit (13) has a plurality of optical surfaces including a first optical surface (first polarization mirror) (13a), a second optical surface (second polarization mirror) (13b), a third optical surface (polarization beam splitter) (13c), and a fourth optical surface (mirror) (13d). The first optical surface (13a) is positioned closer to the incident light than the second optical surface (13b). The second optical surface (13b) is positioned closer to the incident light than the third optical surface (13c). The third optical surface (13c) is positioned closer to the incident light than the fourth optical surface (13d).

[0017] The first optical surface (13a) has the characteristic of transmitting 50% of P-polarized light (polarized light polarized in the first direction) and reflecting 50% of S-polarized light (polarized light polarized in the second direction). The second optical surface (13b) has the characteristic of transmitting 100% of P-polarized light and reflecting 50% of S-polarized light (transmitting 50% of S-polarized light). The third optical surface (13c) has the characteristic of transmitting 100% of P-polarized light and reflecting 100% of S-polarized light. The fourth optical surface (13d) has the characteristic of reflecting 100% of P-polarized light. Thus, the first polarizing mirror and the second polarizing mirror do not need to have a transmittance of 0% or 100% of P-polarized light or S-polarized light, respectively. The polarizing beam splitter has a transmittance of 0% for S-polarized light and 100% for P-polarized light. In this embodiment, P-polarized light is polarized light polarized in the x-direction (first direction), and S-polarized light is polarized light polarized in the y-direction (second direction).

[0018] The aforementioned characteristics of each optical surface possess ideal characteristics. In reality, each optical surface is composed of a dielectric film or a metal film, and the actual characteristics often deviate from the ideal characteristics. With reference to FIGS. 2a, 2b, 2c, and 2d, the film characteristics of the first optical surface (13a), the second optical surface (13b), the third optical surface (13c), and the fourth optical surface (13d) are described. FIGS. 2a, 2b, 2c, and 2d are drawings illustrating the film characteristics of the first optical surface (13a), the second optical surface (13b), the third optical surface (13c), and the fourth optical surface (13d), respectively. In FIGS. 2a, 2b, and 2c, the horizontal axis represents wavelength (nm) and the vertical axis represents transmittance (%), respectively. In FIG. 2d, the horizontal axis represents wavelength (nm) and the vertical axis represents reflectance (%), respectively.

[0019] In this embodiment, the first optical surface (13a), the second optical surface (13b), and the third optical surface are each composed of a dielectric multilayer film, and the fourth optical surface (13d) is composed of a metal film. Each optical surface may be composed of a dielectric multilayer film, a metal film, a wire grid, or a metasurface. Alternatively, each optical surface may be composed of a hybrid film in which a dielectric film and a metal film are mixed. The fourth optical surface (13d) may reflect light through total internal reflection.

[0020] In this embodiment, the primary material of the waveguide of the polarization separation unit (13) is, for example, S-BSL7 (OHARA), but is not limited thereto. Additionally, the waveguide may be made of plastic as long as it is a transparent material.

[0021] The light beam incident on the polarization separation unit (13) is divided (separated) into multiple light beams (rays) L1a, L1b, L1c, and L1d, and is emitted as a predetermined polarized light. Light beams L1a and L1d are emitted as P-polarized light. Light beams L1b and L1c are emitted as S-polarized light and are converted into P-polarized light at the λ / 2 wave plate (14). Light is emitted from the light source device (10) as P-polarized light that is magnified four times. The λ / 2 wave plate (14) may be placed on the emission side of light beams L1a and L1d to be configured to emit as S-polarized light. To increase the degree of polarization, a polarizing plate, etc., may be placed on the emission side of the λ / 2 wave plate (14).

[0022] Next, a display device (30) according to the present embodiment will be described with reference to FIGS. 3a and 3b. FIGS. 3a and 3b are configuration diagrams of the display device (30). FIG. 3a shows the display device (30) viewed from the y-direction, and FIG. 3b shows the display device (30) viewed from the x-direction. The display device (30) has a light guide plate (light guide element) (21). The light guide plate (21) has an incident part (21a) into which light from a light source (11) is incident, and an output part (22b) into which light is emitted.

[0023] The light source (11) of the light source device (10) is a light source that emits image light. The image light is a light beam emitted from a display element such as an OLED or LCD panel. In this embodiment, the light source (11) is an OLED light source that emits image light in a blue band (main wavelength 450 nm), a green band (main wavelength 520 nm), and a red band (640 nm), but is not limited to this.

[0024] The light beam emitted from the light source (11) (light from the light source (11)) passes through the optical system (12), enters the polarization separation unit (13), and is emitted from the light source device (10) as a P-polarized light beam (P-polarized light). The P-polarized light emitted from the light source device (10) enters the incident unit (21a). The light beam reflected from the incident unit (21a) propagates through the interior of the light guide plate (21) via total internal reflection, is divided into multiple light beams at the exit unit (21b), and is emitted into the pupil SP. The incident unit (21a) is composed of a reflective surface, and the exit unit (21b) is composed of multiple transmissive reflective surfaces. The incident unit (21a) and the exit unit (21b) may use a diffraction grating, a metasurface, or a holographic element.

[0025] Next, a lighting system (40) according to the present embodiment will be described with reference to FIGS. 4a and 4b. FIGS. 4a and 4b are configuration diagrams of a lighting system. FIG. 4a shows the lighting system (40) viewed from the y-direction, and FIG. 4b shows the lighting system (40) viewed from the x-direction.

[0026] The lighting system (40) is configured to include a light source device (10) and a second polarization separation unit (31) and illuminates a liquid crystal panel (33). The light source (11) of the light source device (10) is an LED, a laser, a mercury lamp, etc. The emitted light beam from the light source (11) is parallelized in the optical system (12) and emitted as a plurality of P-polarized light beams (polarization in the x-direction) in the polarization separation unit (13).

[0027] P-polarized light emitted from the light source device (10) is separated into multiple light beams by the second polarization separation unit (31) and emitted, and passes through the λ / 4 wavelength plate (32) to illuminate the liquid crystal panel (33). The light beam modulated by the liquid crystal panel (33) passes through the second polarization separation unit (31) and is emitted from the illumination system (40). The illumination system (40) is applied to a projector that projects the light beam emitted from the illumination system (40) onto a surface to be illuminated through a projection system (not shown). The illumination system (40) may be applied to Augmented Reality (AR) glasses that project onto the pupil through an optical system and a light guide plate. Alternatively, the illumination system (40) is applied to a head-mounted display such as Virtual Reality (VR) or Mixed Reality (MR) that projects onto the pupil through an optical system.

[0028] The inequalities in this embodiment are described below. Each of the inequalities described below in this embodiment is applicable to each embodiment described later.

[0029] The following inequalities (1) and (2) may be satisfied:

[0030] 5≤TP1≤75 (1)

[0031] RS1≥75 (2)

[0032] At this time, TP1 is the transmittance (%) of the main wavelength of the polarized light (P-polarized light) polarized in the first direction on the first optical plane (13a), and RS1 is the reflectance (%) of the main wavelength of the polarized light (S-polarized light) polarized in the second direction on the first optical plane (13a).

[0033] When TP becomes greater than the upper limit of inequality (1), the relative light intensity of the light flux L1a increases. On the other hand, when TP1 is smaller than the lower limit of inequality (1), the relative light intensity weakens, and the light quantity distribution of the light flux emitted from the polarization separation unit (13) becomes non-uniform. When RS1 is smaller than the lower limit of inequality (2), unwanted polarized light is emitted from the light flux L1a, and the light utilization efficiency decreases.

[0034] Inequalities (1) and (2) may be replaced with the following inequalities (1a) and (2a):

[0035] 7≤TP1≤65 (1a)

[0036] RS1≥85 (2a)

[0037] Inequalities (1) and (2) may be replaced with the following inequalities (1b) and (2b):

[0038] 9≤TP1≤60 (1b)

[0039] RS1≥90 (2b)

[0040] The following inequalities (3) and (4) may be satisfied:

[0041] 5≤RS2≤75 (3)

[0042] TP2≥75 (4)

[0043] At this time, TP2 is the transmittance (%) of the main wavelength of the polarized light (P-polarized light) polarized in the first direction on the second optical plane (13b), and RS2 is the reflectance (%) of the main wavelength of the polarized light (S-polarized light) polarized in the second direction on the second optical plane (13b).

[0044] When RS2 becomes greater than the upper limit of inequality (3), the relative light intensity of the light flux L1b increases. On the other hand, when RS2 is smaller than the lower limit of inequality (3), the relative light intensity decreases, and the light quantity distribution of the light flux emitted from the polarization separation unit (13) becomes non-uniform. When TP2 is smaller than the lower limit of inequality (4), unwanted polarized light is emitted from the light flux L1b, and the light utilization efficiency decreases.

[0045] Inequalities (3) and (4) may be replaced with the following inequalities (3a) and (4a):

[0046] 7≤RS2≤65 (3a)

[0047] TP2≥85 (4a)

[0048] Inequalities (3) and (4) may be replaced with the following inequalities (3b) and (4b):

[0049] 9≤RS2≤60 (3b)

[0050] TP2≥90 (4b)

[0051] The following inequality (5) or inequality (6) may be satisfied:

[0052] IoS / IoP≤0.2 (5)

[0053] IoS / IoP≥5.0 (6)

[0054] At this time, IoP is the light intensity of the first-direction polarized light (P-polarized light) emitted from the polarization separation unit (13), and IoS is the light intensity of the second-direction polarized light (S-polarized light) emitted from the polarization separation unit (13).

[0055] If IoS / IoP is greater than the upper limit of inequality (5) or less than the lower limit of inequality (6), the unwanted light emitted from the polarization separation unit (13) increases, and the light utilization efficiency decreases.

[0056] Inequalities (5) and (6) may be replaced with the following inequalities (5a) and (6a):

[0057] IoS / IoP≤0.15 (5a)

[0058] IoS / IoP≥6.5 (6a)

[0059] Inequalities (5) and (6) may be replaced with the following inequalities (5b) and (6b):

[0060] IoS / IoP≤0.10 (5b)

[0061] IoS / IoP≥10.0 (6b)

[0062] The following inequalities (7) and (8) may be satisfied:

[0063] TP3≥75 (7)

[0064] RS3≥75 (8)

[0065] At this time, TP3 is the transmittance (%) of the main wavelength of the polarized light (P-polarized light) polarized in the first direction on the third optical plane (13c), and RS3 is the reflectance (%) of the main wavelength of the polarized light (S-polarized light) polarized in the second direction on the third optical plane (13c).

[0066] If TP3 is smaller than the lower limit of inequality (7) or RS3 is smaller than the lower limit of inequality (8), the light flux L1c emitted as unwanted polarized light increases, and the light utilization efficiency decreases.

[0067] Inequalities (7) and (8) may be replaced with the following inequalities (7a) and (8a):

[0068] TP3≥85 (7a)

[0069] RS3≥85 (8a)

[0070] Inequalities (7) and (8) may be replaced with the following inequalities (7b) and (8b):

[0071] TP3≥90 (7b)

[0072] RS3≥90 (8b)

[0073] The following inequality (9) may be satisfied:

[0074] RP4≥75 (9)

[0075] At this time, RP4 is the reflectance (%) of the main wavelength of the polarized light (P-polarized light) polarized in the first direction on the fourth optical plane (13d).

[0076] If RP4 is smaller than the lower limit of inequality (9), the amount of light emitted from the light flux L1d decreases, and the light utilization efficiency decreases.

[0077] Inequality (9) may be replaced with the following inequality (9a):

[0078] RP4≥85 (9a)

[0079] Inequality (9) may be replaced with the following inequality (9b):

[0080] RP4≥90 (9b)

[0081] The following inequality (10) may be satisfied:

[0082] 0.3≤IiS / IiP≤0.7 (10)

[0083] At this time, IiP is the light intensity of the first-direction polarized light (P-polarized light) incident on the polarization separation unit (13), and IiS is the light intensity of the second-direction polarized light (S-polarized light) incident on the polarization separation unit (13).

[0084] If IiS / IiP is greater than the upper limit of the inequality (10) or less than the lower limit, the light intensity distribution of the light beam emitted from the polarization separation unit (13) becomes non-uniform.

[0085] Inequality (10) may be replaced with the following inequality (10a):

[0086] 0.35≤IiS / IiP≤0.65 (10a)

[0087] Inequality (10b) may be replaced with the following inequality (10b):

[0088] 0.40≤IiS / IiP≤0.60 (10b)

[0089] The following inequality (11) may be satisfied:

[0090] 80 / n≤TP1≤320 / n (11)

[0091] At this time, n (in this embodiment, n=4) is the number of multiple optical planes in the polarization separation unit (13).

[0092] When TP1 becomes larger than the upper limit of inequality (11), the relative light intensity of the light flux L1a becomes stronger, and the light quantity distribution of the light flux emitted from the polarization separation unit (13) becomes non-uniform. On the other hand, when TP1 becomes smaller than the lower limit of inequality (11), the relative light intensity of the light flux L1a becomes weaker, and the light quantity distribution of the light flux emitted from the polarization separation unit (13) becomes non-uniform.

[0093] Inequality (11) may be replaced with the following inequality (11a):

[0094] 100 / n≤TP1≤300 / n (11a)

[0095] Inequality (11) may be replaced with the following inequality (11b):

[0096] 140 / n≤TP1≤260 / n (11b)

[0097] The following inequality (12) may be satisfied:

[0098] 80 / n≤RS2≤320 / n (12)

[0099] When RS2 becomes greater than the upper limit of inequality (12), the relative light intensity of the light flux L1b becomes stronger, and the light quantity distribution of the light flux emitted from the polarization separation unit (13) becomes non-uniform. On the other hand, when RS2 becomes smaller than the lower limit of inequality (12), the relative light intensity of the light flux L1b becomes weaker, and the light quantity distribution of the light flux emitted from the polarization separation unit (13) becomes non-uniform.

[0100] Inequality (12) may be replaced with the following inequality (12a):

[0101] 100 / n≤RS2≤300 / n (12a)

[0102] Inequality (12) may be replaced with the following inequality (12b):

[0103] 140 / n≤RS2≤260 / n (12b)

[0104] In the present embodiment, the second optical surface (13b) may be composed of a plurality of dielectric films. The second optical surface (13b) is, for example, composed of 14 layers of Al2O3 (n=1.62, λ=550 nm) and 14 layers of SiO2 (n=1.46, λ=550 nm) alternately stacked. The plurality of dielectric films included in the second optical surface (13b) may include at least 5 layers of dielectric films. The following inequalities (13) and (14) may be satisfied:

[0105] nG <nH2<1.2×nG (13)

[0106] 0.8×nG <nL2<nG (14)

[0107] At this time, nG is the refractive index of the waveguide of the polarization separation part (13), nH2 is the refractive index of at least 5 layers of dielectric film (in this embodiment, Al2O3) having the highest refractive index on the second optical plane (13b), and nL2 is the refractive index of at least 5 layers of dielectric film (in this embodiment, SiO2) having the lowest refractive index on the second optical plane (13b).

[0108] If nH2 is greater than the upper limit of inequality (13) or less than the lower limit, or if nL2 is greater than the upper limit of inequality (14) or less than the lower limit, the desired membrane characteristics cannot be obtained.

[0109] Inequalities (13) and (14) may be replaced with the following inequalities (13a) and (14a):

[0110] nG <nH2<1.15×nG (13a)

[0111] 0.85×nG <nL2<nG (14a)

[0112] Inequalities (13) and (14) may be replaced with the following inequalities (13b) and (14b):

[0113] nG <nH2<1.10×nG (13b)

[0114] 0.90×nG <nL2<nG (14b)

[0115] In the present embodiment, the first optical surface (13a) may be composed of a plurality of dielectric films. The first optical surface (13a) is, for example, composed of 21 layers of TiO2 (n=2.39, λ=550 nm) and 20 layers of Al2O3 (n=1.62, λ=550 nm) alternately stacked. The first optical surface (13a) may include at least 5 layers. The following inequalities (15) and (16) may be satisfied:

[0116] 2.0 <nH1<3.0 (15)

[0117] 1.4 <nL1<2.0 (16)

[0118] At this time, nH1 is the refractive index of the dielectric film (Al2O3 in this embodiment) having the highest refractive index among at least five layers on the first optical plane (13a).

[0119] If nH1 is greater than the upper limit of inequality (15) or inequality (16), or less than the lower limit, the desired membrane properties cannot be obtained.

[0120] Inequalities (15) and (16) may be replaced with the following inequalities (15a) and (16a):

[0121] 2.1 <nH1<2.8 (15a)

[0122] 1.45 <nL1<1.8 (16a)

[0123] Inequalities (15) and (16) may be replaced with the following inequalities (15b) and (16b):

[0124] 2.2 <nH1<2.6 (15b)

[0125] 1.5 <nL1<1.7 (16b)

[0126] The following inequality (17) may be satisfied:

[0127] 30≤θ≤60 (17)

[0128] At this time, θ(°) is the absolute value of the angle between the optical axis O1 of the optical system (12) and the first optical plane (13a), as shown in FIG. 1.

[0129] If the lower limit of the θ inequality (17) is lower or greater than the upper limit, the light flux reflected totally from the side of the waveguide of the polarization separation unit (13) increases, and the light utilization efficiency decreases.

[0130] Inequality (17) may be replaced with the following inequality (17a):

[0131] 35≤θ≤55 (17a)

[0132] Inequality (17) may be replaced with the following inequality (17b):

[0133] 40≤θ≤50 (17b)

[0134] The third optical surface (13c) is composed of, for example, 22 layers of SiO2 (n=1.46, λ=550 nm) and 21 layers of Y2O3 (n=1.80, λ=550 nm) alternately stacked.

[0135] The fourth optical surface (13d) may be composed of a metal film. The fourth optical surface (13d) may be composed of a single layer of Ag (silver). Accordingly, a high reflectance of P-polarized light in the visible band can be obtained.

[0136] Example 2

[0137] Next, with reference to FIG. 5, a light source device (50) according to Embodiment 2 of the present disclosure will be described. FIG. 5 is a configuration diagram of a light source device (50). The light source device (50) is configured to include a light source (51), an optical system (52), a polarization separation unit (53), and a λ / 2 wavelength plate (phase plate) (54).

[0138] The polarization separation section (53) has a first optical plane (53a), a second optical plane (53b), a fifth optical plane (53c), a third optical plane (53d), a sixth optical plane (53e), and a fourth optical plane (53f) in order from the incident section of light from the light source (51).

[0139] The first optical surface (53a) has the characteristic of transmitting 33.3% of P-polarized light and reflecting 100% of S-polarized light. The second optical surface (53b) has the characteristic of transmitting 100% of P-polarized light and reflecting 33.3% of S-polarized light. The fifth optical surface (53c) has the characteristic of transmitting 100% of P-polarized light and reflecting 50.0% of S-polarized light. The third optical surface (53d) has the characteristic of transmitting 100% of P-polarized light and reflecting 100% of S-polarized light. The sixth optical surface (53e) has the characteristic of reflecting 50.0% of P-polarized light. The fourth optical surface (53f) has the characteristic of reflecting 100% of P-polarized light.

[0140] The light beam incident on the polarization separation unit (53) is divided into multiple light beams L5a, L5b, L5c, L5d, L5e, and L5f, and is emitted as a predetermined polarized light. Light beams L5a, L5e, and L5f are emitted as P-polarized light. Light beams L5b, L5c, and L5d are emitted as S-polarized light and are converted into P-polarized light at the λ / 2 wavelength plate (54). Light is emitted from the light source device (50) as P-polarized light that is magnified six times.

[0141] Example 3

[0142] Next, with reference to FIG. 6, a light source device (60) according to Embodiment 3 of the present disclosure will be described. FIG. 6 is a configuration diagram of a light source device (60). The light source device (60) is configured to include a light source (61), an optical system (62), a polarization separation unit (63), and a λ / 2 wavelength plate (phase plate) (64).

[0143] The polarization separation section (63) has a first optical plane (63a), a second optical plane (63b), a fifth optical plane (63c), a sixth optical plane (63d), a third optical plane (63e), a seventh optical plane (63f), an eighth optical plane (63g), and a fourth optical plane (63h) in order from the incident section of light from the light source (61).

[0144] The first optical surface (63a) has the characteristic of transmitting 25.0% of P-polarized light and reflecting 100% of S-polarized light. The second optical surface (63b) has the characteristic of transmitting 100% of P-polarized light and reflecting 25.0% of S-polarized light. The fifth optical surface (63c) has the characteristic of transmitting 100% of P-polarized light and reflecting 33.3% of S-polarized light. The sixth optical surface (63d) has the characteristic of transmitting 100% of P-polarized light and reflecting 50.0% of S-polarized light.

[0145] The third optical surface (63e) has the characteristic of transmitting 100% of P-polarized light and reflecting 100% of S-polarized light.

[0146] The seventh optical surface (63f) has the characteristic of reflecting 33.3% of P-polarized light. The eighth optical surface (63g) has the characteristic of reflecting 50% of P-polarized light. The fourth optical surface (63h) has the characteristic of reflecting 100% of P-polarized light.

[0147] The light beam incident on the polarization separation unit (63) is divided into multiple light beams L6a, L6b, L6c, L6d, L6e, L6f, L6g, and L6h, and is emitted as a predetermined polarized light. Light beams L6a, L6f, L6g, and L6h are emitted as P-polarized light. Light beams L6b, L6c, L6d, and L6e are emitted as S-polarized light and are converted into P-polarized light at the λ / 2 wavelength plate (64). Light is emitted from the light source device (60) as P-polarized light magnified eight times.

[0148] Example 4

[0149] Next, with reference to FIG. 7, a light source device (70) according to Embodiment 4 of the present disclosure will be described. FIG. 7 is a configuration diagram of a light source device (70). The light source device (70) is configured to include a light source (71), an optical system (72), a polarization separation unit (73), and a λ / 2 wavelength plate (phase plate) (74). The polarization separation section (73) is symmetric with respect to the optical axis O7. The polarization separation section (73) has a first optical plane (73a), a second optical plane (73b), a third optical plane (73c), and a fourth optical plane (73d) in order from the incident section of light from the light source (71). The first optical plane (73a) has the characteristic of transmitting 50% of P-polarized light and reflecting 100% of S-polarized light. The second optical plane (73b) has the characteristic of transmitting 100% of P-polarized light and reflecting 50% of S-polarized light. The third optical plane (73c) has the characteristic of transmitting 100% of P-polarized light and reflecting 100% of S-polarized light. The fourth optical plane (73d) has the characteristic of reflecting 100% of P-polarized light.

[0150] Among the light beams incident on the polarization separation unit (73), the light beam in the +x direction from the optical axis O7 is divided into a plurality of light beams (first light beams) L7a1, L7b1, L7c1, and L7d1. Among the light beams incident on the polarization separation unit (73), the light beam in the -x direction from the optical axis O7 is divided into a plurality of light beams (second light beams) L7a2, L7b2, L7c2, and L7d2.

[0151] Light beams L7a1, L7d1, L7a2, and L7d2 are emitted as P-polarized light, and light beams L7b1, L7c1, L7b2, and L7c2 are emitted as S-polarized light and are converted into P-polarized light at a λ / 2 wavelength plate (74). Light is emitted from the light source device (70) as P-polarized light that is magnified three times.

[0152] Example 5

[0153] Next, with reference to FIG. 8, a light source device (80) according to Embodiment 5 of the present disclosure will be described. FIG. 8 is a configuration diagram of a light source device (80). The light source device (80) is configured to include a light source (81), an optical system (82), a polarization separation unit (83), and a λ / 2 wavelength plate (phase plate) (84).

[0154] The polarization separation unit (83) has a first substrate (831), a second substrate (832), a third substrate (833), and a fourth substrate (834) in order from the incident portion of light from the light source (81). The incident surface of the first substrate (831) has the characteristic of transmitting 50% of P-polarized light and reflecting 100% of S-polarized light. The incident surface of the second substrate (832) has the characteristic of transmitting 100% of P-polarized light and reflecting 50% of S-polarized light. The incident surface of the third substrate (833) has the characteristic of transmitting 100% of P-polarized light and reflecting 100% of S-polarized light. The incident surface of the fourth substrate (834) has the characteristic of reflecting 100% of P-polarized light. A reflection-preventing film is formed on the output surfaces of the first substrate (831), the second substrate (832), the third substrate (833), and the fourth substrate (834), respectively.

[0155] The light beam incident on the polarization separation unit (83) is divided into multiple light beams L8a, L8b, L8c, and L8d, and is emitted as a predetermined polarized light. Light beams L8a and L8d are emitted as P-polarized light. Light beams L8b and L8c are emitted as S-polarized light and are converted into P-polarized light at the λ / 2 wavelength plate (84). Light is emitted from the light source device (80) as P-polarized light that is magnified four times.

[0156] The following inequality (18) may be satisfied:

[0157] di≤1.0(i=1, 2, 3) (18)

[0158] At this time, di(mm) is the thickness of the i-th substrate.

[0159] When di becomes larger than the upper limit of the inequality (18), asymmetry occurs and image quality deteriorates.

[0160] Inequality (18) may be replaced with the following inequality (18a):

[0161] di≤0.7(i=1, 2, 3) (18a)

[0162] Inequality (18) may be replaced with the following inequality (18b):

[0163] di≤0.5(i=1, 2, 3) (18b)

[0164] Each embodiment can provide a light source device, a display device, and a polarization separation device with increased light utilization efficiency.

[0165] Although the present invention has been described with reference to exemplary embodiments, it is obvious that the invention is not limited to these embodiments. The scope of protection of the following claims shall be interpreted as broadly as possible to encompass all variations, equivalent structures, and functions.

Claims

Claim 1 A polarization separation device configured to separate light from a light source and emit a plurality of polarized light, comprising a plurality of optical surfaces including a first optical surface, a second optical surface, and a third optical surface, wherein the first optical surface is positioned closer to the incident portion of the light on the polarization separation device than the second optical surface, and the second optical surface is positioned closer to the incident portion than the third optical surface, and the polarization separation device satisfies the following inequality: 5≤TP1≤75 RS1≥75 where TP1 is the transmittance (%) of the main wavelength of the polarized light polarized in the first direction on the first optical plane, and RS1 is the reflectance (%) of the main wavelength of the polarized light polarized in the second direction on the first optical plane. Claim 2 A light source device comprising a light source and a polarization separation device as described in Claim 1. Claim 3 In Clause 2, a light source device satisfying the following inequality: TP2≥75 5≤RS2≤75 where TP2 is the transmittance (%) of the main wavelength of the polarized light polarized in the first direction on the second optical surface, and RS2 is the reflectance (%) of the main wavelength of the polarized light polarized in the second direction on the second optical surface. Claim 4 In Clause 2, a light source device satisfying the following inequality: IoS / IoP ≤ 0.2 or IoS / IoP ≥ 5.0, where IoP is the light intensity of the polarized light polarized in the first direction emitted from the polarization separation device, and IoS is the light intensity of the polarized light polarized in the second direction emitted from the polarization separation device. Claim 5 In Clause 2, a light source device satisfying the following inequality: TP3≥75 RS3≥75 where TP3 is the transmittance (%) of the main wavelength of the polarized light polarized in the first direction on the third optical plane, and RS3 is the reflectance (%) of the main wavelength of the polarized light polarized in the second direction on the third optical plane. Claim 6 A light source device according to claim 2, wherein the first optical surface is a first polarizing mirror, the second optical surface is a second polarizing mirror, and the third optical surface is a polarizing beam splitter. Claim 7 In claim 2, the polarization separation device has a fourth optical plane, the third optical plane is positioned closer to the incident portion than the fourth plane, and the light source device satisfies the following inequality: RP4≥75 where RP4 is the reflectance (%) of the main wavelength of the polarized light polarized in the first direction on the fourth optical plane. Claim 8 In claim 7, the light source device in which the fourth optical surface is a mirror. Claim 9 In Clause 2, a light source device satisfying the following inequality: 0.3≤IiS / IiP≤0.7, where IiP is the light intensity of the first-direction polarized light incident on the polarization separation device, and IiS is the light intensity of the second-direction polarized light incident on the polarization separation device. Claim 10 A light source device further equipped with a phase plate in Clause 2. Claim 11 In item 10, the above-mentioned phase plate is a light source device disposed on the respective emission side of the second optical plane and the third optical plane. Claim 12 In Clause 2, a light source device satisfying the following inequality: 80 / n≤TP1≤320 / n, where n is the number of optical planes. Claim 13 In Clause 2, a light source device satisfying the following inequality: 80 / n≤RS2≤320 / n where n is the number of optical planes and RS2 is the reflectance (%) of the main wavelength of the polarized light polarized in the second direction on the second optical plane. Claim 14 In claim 2, the second optical surface comprises a plurality of dielectric films, and the light source device satisfies the following inequality: nG <nH2<1.2×nG 0.8×nG <nL2<nG이때 nG는 상기 편광 분리장치의 도파부의 굴절률이고, nH2는 상기 제2광학면 상의 가장 높은 굴절률을 갖는 적어도 5층의 유전체막의 굴절률이고, nL2는 상기 제2광학면 상의 가장 낮은 굴절률을 갖는 적어도 5층의 유전체막의 굴절률이다. Claim 15 A light source device according to claim 2, further comprising an optical system having multiple lenses. Claim 16 In claim 15, the optical system is a light source device disposed between the light source and the polarization separation device. Claim 17 A light source device according to claim 2, wherein the polarized light polarized in the first direction is P-polarized light and the polarized light polarized in the second direction is S-polarized light. Claim 18 A light source device satisfying the following inequality in any one of Clauses 2 through 17: 100≥RS1≥75. Claim 19 In Clause 5, a light source device satisfying the following inequality: 100≥TP3≥75 100≥RS3≥75. Claim 20 In Clause 7, a light source device satisfying the following inequality: 100≥RP4≥75. Claim 21 A light source device as described in any one of claims 2 to 17, 19 and 20, and a display device having a light guide element. Claim 22 In Clause 21, a display device satisfying the following inequality: 100≥RS1≥75. Claim 23 In claim 1, a polarization separation device satisfying the following inequality: 100≥RS1≥75. Claim 24 An illumination system comprising a light source device as described in any one of claims 2 to 17, 19 and 20, a second polarization separator, and a liquid crystal panel, wherein a light beam emitted from the light source is parallelized by the polarization separator and emitted as a first plurality of light beams of light polarized in the first direction, and the light polarized in the first direction emitted from the light source device is divided by the second polarization separator and emitted as a second plurality of light beams to illuminate the liquid crystal panel, and the light beam is modulated by the liquid crystal panel and passes through the second polarization separator to be emitted from the illumination system. Claim 25 In claim 24, a lighting system further comprising a projector that projects a luminous flux emitted from the lighting system onto a surface to be illuminated. Claim 26 In paragraph 25, a lighting system applied to an Augmented Reality (AR) device, Virtual Reality (VR) device, or Mixed Reality (MR) device configured to project onto the pupil. Claim 27 Use of the polarization separation device described in claim 1 in a projector configured to project a light beam onto a surface to be irradiated.

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