JP7232360B2 - Polarizing beam splitters and display systems - Google Patents

Description

The present invention relates to polarizing beam splitters and display systems.

A polarizing beam splitter (PBS) is an optical element that splits incident light by reflecting some of the light and transmitting others according to its polarization, e.g., directing polarized light to a light modulator in a display system. It is used to direct the light modulated by the light modulator to the user.

US Pat. No. 5,300,009 discloses a display system comprising a PBS, a light source, reflective optical elements, and a light modulator. A front polarizer is placed between the PBS and the light source such that when light from the light source passes through the front polarizer, one of its polarization components (e.g., the S-polarization component) enters the PBS and is reflected by the polarizer of the PBS to the optical element. reflected towards. Further, a quarter-wave plate is arranged between the PBS and the reflective optical element, and the light reflected by the PBS and the light reflected by the reflective optical element pass through the quarter-wave plate to change the polarization. It is converted into P-polarized light, passes through the polarizer of the PBS, and is sent to the optical modulator. The reflective optical element may be a concave mirror, thereby converging light. The light modulator, for example an LCOS modulator, modulates incident light to form an image, converts it into S-polarized light, and reflects it toward the PBS. Light modulated by the light modulator enters the PBS and is reflected towards the user by the polarizer of the PBS. A refractive optical element may be placed between the PBS and the user to focus the light.
Patent Document 1: Japanese Patent Publication No. 2019-512108

Problem to be solved

However, in order to control the reflection and transmission of light by the polarizers of the PBS, optical elements for converting the polarization of the light must be placed between the PBS and each of the light source, reflective optical element, and light modulator. However, the size of the display system could not always be small enough.

General disclosure

(Item 1)
The polarizing beam splitter may comprise a first prism having mutually intersecting first, second and third surfaces.
The polarizing beam splitter has a fourth surface arranged to face the third surface, a fifth surface having a curved surface that intersects with the fourth surface, and a reflecting surface that reflects light inward. and a sixth surface that intersects each of the fourth and fifth surfaces.
The polarizing beam splitter may comprise a polarizing member having a polarizer arranged between the third surface and the fourth surface, and a first wave plate provided on one surface side of the polarizer facing the fourth surface. .
(Item 2)
The polarizing member may further have a second wave plate provided on the other surface side of the polarizer facing the third surface.
(Item 3)
The second surface may be provided with a reflective surface that reflects light inward.
(Item 4)
The second surface may be curved.
(Item 5)
The polarizing member may further comprise a viewing angle compensation film provided on the first waveplate.
(Item 6)
The first waveplate may be secured to the polarizer using a pressure sensitive adhesive.
(Item 7)
The display system may comprise a polarizing beam splitter according to any one of items 1-6.
The display system may comprise a display positioned opposite the first side or the second side.

It should be noted that the above summary of the invention does not list all the features of the invention. Subcombinations of these feature groups can also be inventions.

1 shows the configuration of a polarizing beam splitter according to this embodiment. 1 shows an exploded configuration of a polarizing beam splitter according to this embodiment. 1 shows a schematic configuration of a display system incorporating a polarizing beam splitter according to this embodiment. An example of the incident angle dependence of the phase difference caused by the wave plate is shown. An example of the viewing angle compensation effect of the optical characteristics by the optical compensation film is shown. An example of the wavelength dependence of the retardation caused by the wave plate is shown. An example of the wavelength dependence of retardation produced by a wave plate when an optical compensation film is provided is shown. 4 shows an example of the wavelength dependence of the fast axis caused by a wave plate. An example of the wavelength dependence of the fast axis generated by the wave plate when an optical compensation film is provided is shown. 4 shows the configuration of a polarizing beam splitter according to a first modified example; 1 shows an exploded configuration of a polarizing beam splitter according to a first modification; 1 shows a schematic configuration of a display system incorporating a polarizing beam splitter according to a first modified example; FIG. 11 shows the configuration of a polarization beam splitter according to a second modified example; FIG. FIG. 11 shows an exploded configuration of a polarizing beam splitter according to a second modification; FIG. FIG. 11 shows a schematic configuration of a display system incorporating a polarizing beam splitter according to a second modified example; FIG.

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. Also, not all combinations of features described in the embodiments are essential for the solution of the invention.

1A and 1B respectively show the configuration and the exploded configuration of a polarizing beam splitter (PBS) 1 according to this embodiment. PBS 1 is an optical element that splits incident light by reflecting part of the light (i.e., the S-polarization component) and transmitting the other (the P-polarization component) depending on the polarization, and consists of two prisms 10, 20 and A polarizing member 30 is provided.

The prism 10 is an input prism for inputting light from the outside. The prism 10 is, for example, a triangular prism-shaped cube having two side surfaces 14 and 15 parallel to each other and a first input surface 11, a second input surface 12, and a diagonal surface 13 defined between them as outer surfaces. be. The directions in which the side surfaces 14 and 15 extend perpendicular to each other are defined as the X-axis and Z-axis directions, and the direction in which the side surfaces 14 and 15 are spaced apart is defined as the Y-axis direction.

The side surfaces 14 and 15 have a right-angled triangular shape when viewed from the front (viewed in the +Y direction), and are arranged with the oblique sides facing the +X and +Z directions.

The first input surface 11 (an example of the first surface) is one outer surface of the prism 10 that is defined in the -X direction between one adjacent side (neighboring side on the -X side) of each of the side surfaces 14 and 15. and has a rectangular shape (square shape in this embodiment). External light is input into the prism 10 in the +X direction through the first input surface 11 .

A second input surface 12 (an example of a second surface) is another input surface of the prism 10 defined in the -Z direction between the other adjacent sides (neighboring sides on the -Z side) of the side surfaces 14 and 15. It is an outer surface and has a rectangular shape (square shape in this embodiment). Through the second input surface 12 , light is output from the prism 10 in the -Z direction, and external light is input into the prism 10 in the +Z direction.

A diagonal surface 13 (an example of a third surface) is yet another outer surface of the prism 10 defined between the oblique sides of the side surfaces 14 and 15 in the +X and +Z directions, and has a rectangular shape. Through the diagonal surface 13, light is output from the prism 10 in the +X direction or +Z direction, and external light is input into the prism 10 in the -Z direction.

Prism 10 is fabricated by injection molding using a transparent polymer, for example an acrylic resin such as polymethyl methacrylate resin (PMMA), a polymer such as ethylene tetracyclododecene copolymer (cyclic olefin copolymer, COC). can do. By using such a material, good optical properties, particularly high translucency, and strength can be obtained.

At least one of the first input surface 11 and the second input surface 12 of the prism 10 is curved in the same manner as the reflecting surface 22 of the prism 20 to be described later to bulge outward into an arch-like or dome-like shape, or inwardly. It may be formed into a curved surface that is recessed in an arch shape or an inverted dome shape. Thereby, the prism 10 develops a lens effect, and the light guided inside the prism 10 can be converged or diffused and output to the outside of the prism 10 .

The prism 20 is, for example, an output prism that outputs light forming an image to the outside. The prism 20 is, for example, a substantially triangular prism-shaped cube having two parallel side surfaces 24 and 25 and a diagonal surface 21 defined therebetween, a reflecting surface 22 and an output surface 23 as outer surfaces.

The side surfaces 24 and 25 have a shape in which a right-angled triangle in a front view (viewed in the +Y direction) is connected to an arcuate shape that curves outward with one adjacent side of the triangle as a chord, parallel to the XZ plane and It is arranged with the hypotenuse directed in the -X and -Z directions.

A diagonal surface 21 (an example of a fourth surface) is one outer surface of the prism 20 defined in the -X and -Z directions between the oblique sides of the side surfaces 24 and 25, and has a rectangular shape. The diagonal surface 21 is arranged opposite the diagonal surface 13 of the prism 10 in the PBS1. Through the diagonal surface 21, external light is input into the prism 20 in +Z direction or +X direction, and light is output from the prism 20 in -Z direction.

A reflecting surface 22 (an example of a fifth surface) is another outer surface of the prism 20 defined in a curved shape that intersects the diagonal surface 21 between the arcs of the side surfaces 24 and 25 toward the +Z direction. The expression that the reflecting surface 22, which is a curved surface, intersects the diagonal surface 21, which is a flat surface, means that the normal at any position on the reflecting surface 22 intersects (is not parallel to) the normal of the diagonal surface 21. do. In this embodiment, the curved surface is curved outward (+Z direction) in the XZ plane in an arch shape, but the curved surface is not limited to this, and may be a curved surface curved inward (−Z direction) in a reverse arch shape. , and may be curved not only in the XZ plane but also in the YZ plane to form a dome shape that bulges in the +Z direction or an inverted dome shape that is recessed in the -Z direction. With such a shape, the reflective surface 22 exhibits a lens effect that converges or diffuses light.

The reflecting surface 22 is provided with a reflecting film 22a. The reflective film 22a can be formed by a known thin film formation method such as vacuum deposition or sputtering using a metal such as silver, gold, or aluminum. Thereby, the reflecting surface 22 reflects the light entering the reflecting surface 22 in the +Z direction from inside the prism 20 while concentrating the light inward.

The output surface 23 (an example of the sixth surface) intersects the diagonal surface 21 and the reflecting surface 22 in the +X direction between the adjacent sides (neighboring sides on the +X side) of the side surfaces 24 and 25. , and has a rectangular shape (square shape in this embodiment). Light is output from the prism 20 in the +X direction via the output surface 23 .

In the PBS 1 according to the present embodiment, the reflecting surface 22 of the prism 20 is formed into a curved surface to exhibit a lens effect. It may be formed into a curved surface that bulges in an arch shape or dome shape in the +X direction) or dents inward (−X direction) in a reverse arch shape or a reverse dome shape. As a result, the prism 20 develops a lens effect, converges or diffuses light traveling in the +X direction within the prism 20 , and outputs the light outside the prism 20 .

The prism 20 can be molded using the same material as the prism 10 .

The polarizing member 30 is an optical member that splits incident light by reflecting a portion of the light and transmitting the rest depending on the polarization, and includes a polarizer 31, wave plates 32 and 34, and optical compensation films 32a and 34a. include.

The polarizer 31 is an optical element that transmits the P-polarized component and reflects the S-polarized component. For example, a birefringent polarizer that is formed using a dielectric film, a thin film polarizer that utilizes the incident angle dependence of the reflectance of a dielectric film, or the like can be employed.

The wave plates 32 and 34 (examples of the second and first wave plates, respectively) are optical elements that provide a phase difference (that is, an optical path difference) between two polarization components to convert the polarization state. In this embodiment, the wavelength plate 32 converts linearly polarized light into circularly polarized light or vice versa by giving a phase difference of 1/4 wavelength when light is transmitted. employs a quarter-wave plate that converts P-polarization to S-polarization or S-polarization to P-polarization. The wave plates 32 and 34 are formed in the form of thin films using birefringent materials such as crystal and mica, for example. The wave plate 32 is fixed to one side of the polarizer 31 facing the diagonal surface 13 of the prism 10 via an adhesive layer 33 made of a translucent optical adhesive such as a pressure sensitive adhesive (PSA). be. The wave plate 34 is fixed to the other surface side of the polarizer 31 facing the diagonal surface 21 of the prism 20 via an adhesive layer 35 similar to the adhesive layer 33 .

In the display system 100 described later, a transmissive or self-luminous display is used in place of the reflective display 92 to allow light to enter the prism 10 from the first input surface 11 or the second input surface 12, Furthermore, when the light emitted from the diagonal surface 13 of the prism 10 does not need to be reflected by the polarizing member 30 and returned to the prism 10, such as when entering the prism 20 through the polarizing member 30, the polarizing member 30 has a wavelength plate 32. Also, the optical compensation film 32a may be omitted.

The optical compensation films 32a, 34a degrade the optical properties of the waveplates 32, 34 as the angle of incidence increases when light is incident on the waveplates 32, 34 at an angle of incidence other than 90 degrees. is an optical film that compensates for the viewing angle (also called a viewing angle compensation film). The optical compensation films 32a and 34a are formed into films and fixed on the wave plates 32 and 34 via adhesive layers (not shown) such as PSA, respectively. The optical compensation films 32a and 34a have retardation in the thickness direction opposite in sign to the retardation in the thickness direction of the wave plates 32 and 34, thereby canceling out the retardation in the thickness direction of the wave plates 32 and 34, thereby ensuring the viewing angle. be done. In addition, the optical compensation films 32a and 34a may further have an in-plane retardation of zero so that no in-plane retardation occurs. The viewing angle compensation effect of the optical characteristics by the optical compensation films 32a and 34a will be described later.

The polarizing member 30 is formed by sequentially laminating an optical compensation film 32a, a wave plate 32, a polarizer 31, a wave plate 34, and an optical compensation film 34a on a substrate such as a glass substrate or a film substrate via an adhesive layer. , can be formed while being held on the substrate. Alternatively, the polarizing member 30 is obtained by laminating the polarizer 31, the wavelength plate 32, and the optical compensation film 32a on the first substrate in order via an adhesive layer, fixing the second substrate thereon, and removing the first substrate. Then, the polarizer 31, the wave plate 32, and the optical compensation film 32a are transferred onto the second substrate, and the wave plate 34 and the optical compensation film 34a are sequentially placed on the polarizer 31 transferred onto the second substrate. It can be formed in a state of being held on the second substrate by laminating the substrate through the substrate. In these manufacturing methods, the polarizing member 30 is held with the optical compensation film 32a in contact with the substrate, and the surface of the optical compensation film 34a is exposed.

In the PBS 1, diagonal surfaces 13 and 21 of prisms 10 and 20 are opposed to each other, a polarizing member 30 (polarizer 31) is arranged between them, and they are fixed using an optical adhesive (not shown) such as PSA. It is formed by More specifically, first, the polarizing member 30 held on the substrate is supported with the surface of the optical compensation film 34a facing upward, and the prism 20 is placed above the polarizing member 30 with its diagonal surface 21 facing downward. , the right-angled sides of the polarizing member 30 and the prism 20 are aligned with each other, and the diagonal surface 21 of the prism 20 is pressed against the surface of the optical compensation film 34a via an optical adhesive. Next, the substrate is removed from the polarizing member 30 fixed on the diagonal surface 21 of the prism 20 . Finally, the prism 20 is supported with its diagonal surface 21 facing upward, and the prism 10 is positioned above the polarizing member 30 fixed on the diagonal surface 21 with its diagonal surface 13 facing downward. 30, prism 20, and prism 10 are positioned so that their right-angled sides overlap each other, and the diagonal surface 13 of prism 10 is pressed against the surface of optical compensation film 32a of polarizing member 30 via an optical adhesive. . Thereby, the polarizing member 30 is fixed between the prisms 10 and 20, and they are integrated as the PBS1.

FIG. 2 shows a schematic configuration of a display system 100 incorporating a PBS 1 according to this embodiment. The display system 100 is, for example, a system that forms image light by illuminating a display device 92 with light from a light source 91, converges the image light, and emits the image light toward a user through a light guide plate 93. , a light source 91 , a display 92 , and a light guide plate 93 .

The light source 91 is a device that generates illumination light for illuminating the display 92 . The light source 91 is arranged to face the first input surface 11 of the PBS 1 and emits the illumination light L<b>1 toward the first input surface 11 . A polarizing plate (not shown) may be provided on the light source 91 or the first input surface 11 . By passing through this, the illumination light L1 can enter the polarizing member 30 containing only the circularly polarized component that is converted into S-polarized light through the wave plate 32 as will be described later.

The display 92 is a device that generates image light. For example, the display 92 has a plurality of micromirrors arranged in a matrix on the light-receiving surface. A reflective spatial light modulator (SLM) that modulates light in a linear fashion, an LCOS-SLM that phase-modulates light by voltage-controlling a liquid crystal, or the like may be employed. The display 92 is arranged to face the second input surface 12 of the PBS 1, receives the illumination light L2 output from the second input surface 12, and converts the reflected light into the image light L3 through the second input surface 12. Place in PBS1.

The light guide plate 93 is an optical member that guides image light toward the user. The light guide plate 93 is arranged between the PBS 1 and the user so as to face the output surface 23 of the PBS 1, and guides the image light L5 output from the output surface 23 of the PBS 1 toward the user. Instead of the light guide plate 93 or together with the light guide plate 93, an optical device such as a lens element or an optical device including a plurality of such optical elements to guide the image light toward the user is arranged between the PBS 1 and the user. You may Alternatively, as mentioned above, the output surface 23 may be curved to take part of the function of a lens element or optical device.

In the display system 100 configured as described above, when the illumination light L1 is generated by the light source 91, the illumination light L1 first enters the prism 10 via the first input surface 11. As shown in FIG. Illumination light L1 then exits prism 10 via diagonal surface 13 and enters polarizing member 30 . Here, of the illumination light L1 that has entered the polarizing member 30, the component that is converted to S-polarized light by passing through the wave plate 32 (that is, the circularly-polarized component) is reflected by the polarizer 31 (it should be noted that it is converted to P-polarized light). The opposite circularly polarized component received may be cut by the light source 91 or a waveplate on the first input surface 11). Illumination light L2, which includes only the S-polarized component and is reflected by polarizer 31, returns to prism 10 via wave plate 32 of polarizing member 30, diagonal surface 13, and prism 10 via second input surface 12. It is output to the outside and enters the display 92 .

Next, when the display 92 is illuminated by the illumination light L2, the illumination light L2 is reflected to generate the image light L3. Image light L 3 enters prism 10 via second input surface 12 , exits prism 10 via diagonal surface 13 , and re-enters polarizing member 30 . Here, the illumination light L2 containing only the S-polarized component that was previously reflected by the polarizer 31 passes through the wave plate 32, is reflected by the display 92, and passes through the wave plate 32 again as image light L3. converted to P-polarized light. Accordingly, image light L3 is transmitted through polarizer 31 and enters prism 20 via wave plate 34 of polarizing member 30 and diagonal surface 21 .

After entering the prism 20, the image light L3 enters the curved reflecting surface 22, where it is converged inward and reflected. Converged image light L 4 exits prism 20 via diagonal surface 21 and enters polarizing member 30 . Here, the image light L3 containing only the P-polarized component that has previously passed through the polarizer 31 is transmitted through the wavelength plate 34, reflected by the reflecting surface 22, and transmitted through the wavelength plate 32 again as image light L4. converted to polarized light. Therefore, the image light L4 is reflected by the polarizer 31 and returns to the prism 20 as the image light L5 via the wave plate 34 of the polarizing member 30 and the diagonal surface 21 .

Finally, the image light L5 returned to the prism 20 is output from the prism 20 via the output surface 23 and radiated toward the user via the light guide plate 93. FIG.

In the PBS 1 according to the present embodiment, wave plates 32 and 34 are provided on both sides of the polarizer 31 in the polarizing member 30, respectively. By forming the reflecting surface 22 of the prism 20 in a curved shape, it is possible to compactly configure a polarization beam splitter having a lens function, that is, a lens-integrated polarization beam splitter.

The viewing angle compensation effect by the optical compensation films 32a and 34a provided on the wave plates 32 and 34 of the polarizing member 30 will be described. A demonstration sample was constructed by laminating a wave plate similar to the wave plates 32 and 34 on a substrate and an optical compensation film similar to the optical compensation films 32a and 34a thereon via a PSA. A comparative sample was constructed by fixing only the wave plate on the substrate using PSA. In this example, a blue plate (float glass) having a thickness of 0.7 mm was used as a substrate, a retardation film (FM143) manufactured by Teijin Limited as a wavelength plate, and an NV film manufactured by JX Liquid Crystal Co., Ltd. as an optical compensation film. For the optical compensation film, the in-plane retardation Re = (nx- ny) d=0, that is, nx=ny, and the retardation in the thickness direction Rth=((nx+ny)/2-nz)d is the opposite sign of that of the phase plate, that is, <0. In other words, since the in-plane retardation of the optical compensation film is zero, no in-plane retardation occurs. cancel. In this example, an NV film with Rth=−100 nm was adopted so as to substantially offset Rth=91.8 nm (wavelength: 550 nm) of the wave plate. The demonstration sample and the comparative sample were irradiated with light at an angle, and the phase difference of the light transmitted through the samples was measured using AxoScan (manufactured by Optoscience Co., Ltd.).

3A and 4A show the incident angle dependence and wavelength dependence, respectively, of the phase difference of light generated by the wave plate measured using the comparative sample. The incident angle of light is given with reference to the normal direction of the wave plate. At light wavelengths of 450 nm, 550 nm, 590 nm, and 630 nm, the phase difference is the smallest when the incident angle is 0 degrees, and tends to increase gradually as the incident angle increases. The increase in phase difference at 60 degrees with respect to an incident angle of 0 degrees is 3.50 nm, 5.21 nm, 5.51 nm, and 5.53 nm for wavelengths of 450 nm, 550 nm, 590 nm, and 630 nm, respectively.

3B and 4B show the incident angle dependence and wavelength dependence, respectively, of the phase difference of light produced by the wave plate measured using the demonstration sample. The incident angle of light is given with reference to the normal direction of the wave plate. At light wavelengths of 450 nm, 550 nm, 590 nm, and 630 nm, the phase difference is almost constant from 0 to 40 degrees of incidence, and tends to decrease as the angle of incidence exceeds 50 degrees. The increase in retardation at 60 degrees for 0 degrees of incidence is −0.87 nm, −1.92 nm, −2.05 nm, and −1.80 nm for wavelengths of 450 nm, 550 nm, 590 nm, and 630 nm, respectively. be. As can be seen by comparison with the measurement results of the comparative sample, the provision of the optical compensation film reduces the incident angle dependency of the retardation received by the light transmitted through the wave plate to less than half. In other words, it can be seen that the deterioration of the phase difference caused by the oblique incidence of the light is compensated for the phase difference received by the light passing through the wave plate, and optical characteristics equivalent to those of normal incidence can be obtained over a wide range of incident angles.

FIG. 5A shows an example of the wavelength dependence of the fast axis angle caused by the wave plate measured using the comparative sample. The incident angle of light is given with reference to the normal direction of the wave plate. In the wavelength range of 400 to 780 nm, the fast axis angle for incident angles of 0 degrees and 20 degrees is almost constant regardless of the increase in wavelength, and the fast axis angle for incident angles of 40 degrees and 60 degrees is less than the wavelength. Slowly increases with growth. It also increases toward 0 degrees with increasing incident angle. The increase in the fast axis angle at 60 degrees with respect to the 0 degree incident angle is about 6-9 degrees.

FIG. 5B shows an example of the wavelength dependence of the fast axis angle caused by the waveplate measured using the demonstration sample. The incident angle of light is given with reference to the normal direction of the wave plate. In the wavelength range of 400 to 780 nm, the fast axis angle for incident angles of 0 degrees and 20 degrees is almost constant regardless of the increase in wavelength, and the fast axis angle for incident angles of 40 degrees and 60 degrees is less than the wavelength. It increases slowly with increasing wavelength, exhibits a maximum at about 600 nm, and further decreases slowly with increasing wavelength. In the wavelength ranges of 400 to 480 nm and 700 to 780 nm, the fast axis angle increases in the negative direction as the incident angle increases. The axis angle decreases in the positive direction. The amount of change in the fast axis angle at 60 degrees with respect to the incident angle of 0 degrees is about -4 to 2 degrees, which is about half the change in the comparative sample.

Therefore, by providing the optical compensation films 32a and 34a on the wave plates 32 and 34, respectively, as in the polarizing member 30 according to the present embodiment, the optical effect of oblique incidence of light is substantially the same as that of perpendicular incidence. It becomes possible to obtain a phase difference.

A PBS 1 according to this embodiment includes a prism 10 having a first input surface 11, a second input surface 12, and a diagonal surface 13 that intersect with each other, a diagonal surface 21 arranged to face the diagonal surface 13, and a pair of A prism 20 having a reflecting surface 22 which is formed in a curved shape intersecting with a corner surface 21 and provided with a reflecting film 22a for reflecting light inward, and an output surface 23 intersecting with each of the diagonal surface 21 and the reflecting surface 22. , a polarizing member 30 having a polarizer 31 arranged between the diagonal surfaces 13 and 21 and a wave plate 34 provided on one side of the polarizer 31 facing the diagonal surface 21 . By providing the wave plate 34 in the polarizing member 30 adjacent to the polarizer 31, the reflecting surface 22 of the prism 20 can be formed into a curved surface, and the lens element and the reflecting optical element can be integrated with the prism 20. As a result, it is possible to provide a lightweight and compact PBS 1 having a lens function and a small number of parts.

In the PBS 1 according to the present embodiment, the prism 10 has a first input surface 11 that receives the illumination light L1 and a second input surface 12 that receives the image light L3 generated by illuminating the display 92 using the illumination light L2. However, when there is no need to input the illumination light L1 to the PBS 1, such as when generating image light using a transmissive display or a self-luminous display, the prism 10 has one input surface Only the input surface needs to be provided.

6A and 6B respectively show the configuration and disassembled configuration of the PBS 1a according to the first modification. The PBS 1a comprises two prisms 10a, 20 and a polarizing member 30. FIG. Here, the prism 20 and the polarizing member 30 are constructed in the same manner as those described above.

The prism 10a is an input prism for inputting image light from the outside. The prism 10a is, for example, a triangular prism-shaped cube having two parallel side surfaces 14 and 15 and an input surface 11, a reflecting surface 12, and a diagonal surface 13 defined therebetween as outer surfaces. The side surfaces 14 , 15 , the input surface 11 and the diagonal surface 13 are configured in the same manner as the first input surface 11 and the diagonal surface 13 . The directions in which the side surfaces 14 and 15 extend perpendicular to each other are defined as the X-axis and Z-axis directions, and the direction in which the side surfaces 14 and 15 are spaced apart is defined as the Y-axis direction.

The reflecting surface 12 (an example of the second surface) is an outer surface of the prism 10 defined in the −Z direction between adjacent sides on the −Z side of the side surfaces 14 and 15, and has a rectangular shape (this embodiment square shape). A reflective film 12 a is provided on the reflective surface 12 . The reflective film 12a can be formed by a known thin film forming method such as vacuum deposition or sputtering using a metal such as silver, gold, or aluminum. Thereby, the reflective surface 12 reflects inwardly (+Z direction) the light entering the reflective surface 12 in the -Z direction from inside the prism 10 .

Similar to the prism 10, the prism 10a also uses a transparent polymer such as an acrylic resin such as polymethyl methacrylate resin (PMMA) or a polymer such as ethylene-tetracyclododecene copolymer (cyclic olefin copolymer, COC). can be molded by injection molding. By using such a material, good optical properties, particularly high translucency, and strength can be obtained.

FIG. 7 shows a schematic configuration of a display system 100a incorporating a PBS 1a according to the first modified example. The display system 100a is a system that converges image light generated by the display 92a and radiates it toward the user through the light guide plate 93, and includes the PBS 1a, the display 92a, and the light guide plate 93 described above. The light guide plate 93 is constructed in the same manner as described above.

The display 92a is a device that generates image light. As the display 92a, for example, a transmissive liquid crystal microdisplay using a backlight, a self-luminous organic EL display, or a micro LED display can be adopted. The display 92a is arranged to face the input surface 11 of the PBS 1a, and emits the image light L1 toward the input surface 11. As shown in FIG. Note that the image light L1 may be generated so as to include only the circularly polarized light component that is converted into S-polarized light when passing through the wave plate 32 of the polarizing member 30 .

In the display system 100a configured as described above, when the image light L1 is generated by the display 92a, the image light L1 first enters the prism 10a via the input surface 11. As shown in FIG. Image light L 1 then exits prism 10 via diagonal surface 13 and enters polarizing member 30 . Here, of the image light L1 that has entered the polarizing member 30, the component that is converted to S-polarized light by passing through the wavelength plate 32 (that is, the circularly-polarized component) is reflected by the polarizer 31 (converted to P-polarized light). The opposite circular polarization component is transmitted through the polarizer 31). The image light L2 containing only the S-polarized component reflected by the polarizer 31 returns to the prism 10a via the wave plate 32 of the polarizing member 30 and the diagonal surface 13. FIG.

The image light L2 that has returned to the prism 10a then enters the reflecting surface 12 and is reflected therefrom. The reflected image light L3 exits the prism 10a via the diagonal surface 13 and enters the polarizing member 30 again. Here, the image light L2 containing only the S-polarized component that was previously reflected by the polarizer 31 is transmitted through the wavelength plate 32, reflected by the reflecting surface 12, and transmitted through the wavelength plate 32 again as the image light L3. converted to P-polarized light. Accordingly, image light L3 is transmitted through polarizer 31 and enters prism 20 via wave plate 34 of polarizing member 30 and diagonal surface 21 .

After entering the prism 20, the image light L3 enters the curved reflecting surface 22, where it is converged inward and reflected. Converged image light L 4 exits prism 20 via diagonal surface 21 and enters polarizing member 30 . Here, the image light L3 containing only the P-polarized component that has previously passed through the polarizer 31 is transmitted through the wavelength plate 34, reflected by the reflecting surface 22, and transmitted through the wavelength plate 32 again as image light L4. converted to polarized light. Therefore, the image light L4 is reflected by the polarizer 31 and returns to the prism 20 as the image light L5 via the wave plate 34 of the polarizing member 30 and the diagonal surface 21 .

Finally, the image light L5 returned to the prism 20 is output from the prism 20 via the output surface 23 and radiated toward the user via the light guide plate 93. FIG.

8A and 8B respectively show the configuration and disassembled configuration of PBS 1b according to the second modification. The PBS 1b comprises two prisms 10b, 20 and a polarizing member 30. FIG. Here, the prism 20 and the polarizing member 30 are constructed in the same manner as those described above.

The prism 10b is an input prism for inputting image light from the outside. The prism 10b is, for example, a substantially triangular prism-shaped cube having two parallel side surfaces 14 and 15 and an input surface 11, a reflecting surface 12, and a diagonal surface 13 defined therebetween as outer surfaces. The input surface 11 and the diagonal surface 13 are configured in the same manner as the first input surface 11 and the diagonal surface 13 described above. The directions in which the side surfaces 14 and 15 extend perpendicular to each other are defined as the X-axis and Z-axis directions, and the direction in which the side surfaces 14 and 15 are spaced apart is defined as the Y-axis direction.

The side surfaces 14 and 15 have a shape in which a right-angled triangle in a front view (viewed in the +Y direction) and an arcuate curve that curves outward with one adjacent side as a chord are connected, parallel to the XZ plane and It is arranged with the oblique sides facing the +X and +Z directions.

The reflecting surface 12 (an example of the second surface) is an outer surface of the prism 20 defined in a curved shape that intersects the input surface 11 and the diagonal surface 13 between the arcs of the side surfaces 14 and 15 in the -Z direction. be. It should be noted that the expression that the reflecting surface 12, which is a curved surface, intersects the input surface 11 and the diagonal surface 13, which are flat surfaces, means that the normal at any position on the reflecting surface 12 intersects the normals of the input surface 11 and the diagonal surface 13. It means to do (not parallel). In the present embodiment, the curved surface is curved outward (−Z direction) in the XZ plane in an arch shape, but the curved surface is not limited to this, and may be a curved surface curved inward (+Z direction) in a reverse arch shape. , the XZ plane as well as the YZ plane. With such a shape, the reflective surface 12 exhibits a lens effect that converges or diffuses light.

The reflecting surface 12 is provided with a reflecting film 12a. The reflective film 12a can be formed by a known thin film forming method such as vacuum deposition or sputtering using a metal such as silver, gold, or aluminum. Thereby, the reflecting surface 12 reflects the light entering the reflecting surface 12 in the -Z direction from the inside of the prism 10 while concentrating the light inward.

Similar to prism 10, prism 10b also uses transparent polymers such as acrylic resins such as polymethyl methacrylate resin (PMMA) and polymers such as ethylene-tetracyclododecene copolymer (cyclic olefin copolymer, COC). can be molded by injection molding. By using such a material, good optical properties, particularly high translucency, and strength can be obtained.

FIG. 9 shows a schematic configuration of a display system 100b incorporating a PBS 1b according to the second modified example. The display system 100b is a system that converges the image light generated by the display 92a and emits it toward the user through the light guide plate 93, and includes the PBS 1b, the display 92a, and the light guide plate 93 described above. The display 92a and the light guide plate 93 are constructed in the same manner as those described above.

In the display system 100b, when the image light L2 enters the curved reflective surface 12 within the prism 10b, it is converged and reflected inward by this, and the converged image light L3 is polarized through the diagonal surface 13. It functions similarly to the previously described display system 100a, except that it enters member 30. FIG.

In the PBS 1b according to the modified example, the reflecting surface 12 of the prism 10b is formed into a curved surface to exhibit a lens effect. Alternatively, it may be formed into a curved surface that bulges like a dome, or that is recessed inward like an inverted arch or inverted dome. Thereby, the prism 10 develops a lens effect, and the light guided inside the prism 10 can be converged or diffused and output to the outside of the prism 10 .

In the modified PBSs 1a and 1b, the polarizing member 30 may be configured by laminating the polarizer 31, the wavelength plate 34, and the optical compensation film 34a in order via an adhesive layer. In such a case, the display 92a may generate image light L1 containing only the S-polarized component.

In the PBSs 1a and 1b according to the modifications, the wave plate 34 is provided on at least one surface of the polarizer 31 in the polarizing member 30, so that the wave plate, lens element, and reflecting optical element independent of the PBSs 1a and 1b are not used. By forming the reflecting surface 22 of the prism 20 in a curved shape, it is possible to compactly construct a polarization beam splitter having a lens function, that is, a lens-integrated polarization beam splitter.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is obvious to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the description of the scope of the claims that forms with such modifications or improvements can also be included in the technical scope of the present invention.

The execution order of each process such as actions, procedures, steps, and stages in devices, systems, programs, and methods shown in claims, specifications, and drawings is etc., and it should be noted that they can be implemented in any order unless the output of a previous process is used in a later process. Regarding the operation flow in the claims, specification, and drawings, even if explanations are made using "first," "next," etc. for the sake of convenience, it means that it is essential to carry out in this order. isn't it.

Reference Signs List 10, 10a, 10b, 20 Prism 11 First input surface (input surface) 12 Second input surface (reflective surface) 12a Reflective film 13 Diagonal surface 14, 15 Side surface 21 Diagonal surface 22 Reflective surface 22a Reflective film 23 Output surface 24, 25 Side surface 30 Polarizing member 31 Polarizer 32, 34 Wave plate 32a, 34a Optical compensation film , 33, 35... adhesive layer 91... light source 92, 92a... indicator 93... light guide plate 100, 100a, 100b... display system, L1, L2... illumination light (image light), L3, L4, L5... image light.

Claims (8)

a first prism having first, second, and third surfaces that intersect each other;
A fourth surface arranged to face the third surface, and a reflecting surface formed in a curved surface shape intersecting the fourth surface and reflecting light inward toward the fourth surface. a second prism having five surfaces and a sixth surface that intersects with each of the fourth surface and the fifth surface;
A polarizer arranged between the third surface and the fourth surface, a first wave plate provided on one surface side of the polarizer facing the fourth surface, and a wave plate provided on the first wave plate a polarizing member comprising a viewing angle compensation film;
wherein the viewing angle compensation film has a retardation in the thickness direction opposite in sign to the retardation in the thickness direction of the first wave plate. 2. The polarizing beam splitter according to claim 1, wherein the second surface is provided with a reflective surface that reflects light inward toward the third surface. 3. The polarizing beam splitter of claim 2, wherein said second surface is curved. 4. The polarizing beam splitter according to any one of claims 1 to 3, wherein said second prism is integrally molded including said fourth surface, said fifth surface and said sixth surface. 5. The polarizing beam splitter of any one of claims 1-4, wherein the first waveplate is secured to the polarizer using a pressure sensitive adhesive. The polarizing beam splitter according to any one of claims 1 to 5, wherein the polarizing member further has a second wave plate provided on the other surface side of the polarizer that faces the third surface. The polarizing member further includes another viewing angle compensation film provided on the second wave plate, and the another viewing angle compensation film has thickness direction retardation opposite in sign to thickness direction retardation of the second wave plate. 7. A polarizing beam splitter according to claim 6, comprising: a polarizing beam splitter according to any one of claims 1 to 7 ;
a display arranged to face the first surface or the second surface;
display system.

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