OPTICAL DEVICE

Abstract

Optical device designed to display an image of an outside scene of an area of ​​a blind spot (13) to a viewer (10) when an obstacle (12) is within a viewer's field of vision, wherein the optical device comprises: a light guide (2) with an incident surface (2a) onto which outside scene light (LV), coming from the area of ​​the blind spot (13), falls, a first surface (2b) having several flat sections (3) and several prism sections (4), wherein the outside scene light incident from the incident surface first reaches the first surface, and a second surface (2c) which is arranged opposite the flat sections of the first surface; wherein a light-shielding section (51, 52) is arranged on a surface of the light guide or at a position away from the light guide to block an external light (LD) that would enter the light guide, wherein The flat sections of the first surface totally reflect the outside scene light, which propagates within the light guide, towards the second surface. the second surface totally reflects the outdoor scene light, which was reflected through the flat sections, towards the first surface, Each of the prism sections has an exit surface (4a) for emitting outwards a portion of the external scene light incident from the incident surface and a portion of the external scene light reflected by the second surface, and an inclined surface (4b) which is arranged opposite to the viewer with respect to the exit surface. the light-shielding section comprises a first light-shielding section (51) designed to block external light incident on the inclined surface and a second light-shielding section (52) designed to block external light incident on the flat section in a predetermined direction. in a cross-sectional view that includes a normal to the exit surface and a normal to the flat section, θ is an angle formed between the normal to the flat section and a line connecting a center of a predetermined exit surface and an eye point center (15) of the observer, L is a distance between the center of the predetermined exit surface and the center of the eye point. DL is a distance between the eye center and an outer edge of the eyelids (14) of the viewer from the light guide in a direction perpendicular to the line connecting the center of the predetermined exit surface and the eye center, θmin is an angle defined by θ-tan -1 (DL / L) is represented a straight line A passes through a point (4c) where the exit surface and the inclined surface intersect, and the straight line A is symmetrically incident on the flat section at the angle θmin with respect to the normal to the flat section, a straight line B runs parallel to the straight line A and intersects at a point where the inclined surface and the flat section intersect, the straight line A intersects the flat section at a point P1, the straight line B intersects the flat section at a point P2, the exit surface intersects the flat section at a point P3, A distance Fa is defined between point P1 and point P3. A distance Fb is defined between point P2 and point P3. Fa < Fb is satisfied, and the second light-shielding section is arranged such that it covers straight line A and straight line B.

Description

Technical field

[0001] The present invention relates to an optical device in which light incident from an incident surface of a light guide propagates within the light guide and exits from an exit surface. State of the art

[0002] JP 6 372 305 B2 describes an optical device comprising a light guide, a semi-transparent flat mirror, a plane mirror, and a prism plate with prisms. The light guide has an incident surface onto which light from an external scene is incident, a first surface onto which the light from the external scene, entering the light guide from the incident surface, first reaches, and a second surface opposite the first surface. The semi-transparent flat mirror is arranged on the first surface of the light guide, and the plane mirror is arranged on the second surface. The semi-transparent flat mirror is positioned between the prism plate and the light guide.

[0003] Part of the light from the outside scene, entering through the optical surface of the light guide, is reflected by the semi-transparent flat mirror to the second surface, and the reflected light is reflected by the plane mirror back to the first surface. Part of the light not reflected by the semi-transparent flat mirror is absorbed by it, and the remainder passes through the semi-transparent flat mirror and is emitted from the prism's exit surface to the outside. The prism's exit surface faces the viewer, allowing the viewer to visually perceive the outside scene through the optical device.This optical device is used, for example, as a blind spot aid, enabling a viewer to perceive an outside scene in an area of ​​a blind spot that is blocked by a predetermined obstacle and cannot be directly viewed by the viewer.

[0004] DE 11 2018 005 770 T5 discloses a semiconductor package comprising: a housing with a wall section for surrounding a space in which a semiconductor chip is installed; a prism surface with prism tips and prism valleys; and a flat surface facing the prism surface, wherein the prism surface faces the semiconductor chip, the flat surface is attached to a cover, and the prism surface may have a dam that is formed in a direction of extension that differs from the direction of extension of the prism tips.

[0005] DE 11 2017 007 266 T5 discloses a display device in which a light ray of an image enters from an end face of a light guide plate and the light ray of the image, which is reflected or deflected by each of a plurality of emission structures present on the light guide plate, is emitted from a light exit surface of the light guide plate. A light reflection layer or a light absorption layer is formed on at least one of the optical surfaces present on the emission structure, with the exception of one optical surface that reflects or deflects the light ray of the image.

[0006] DE 11 2017 002 033 T5 discloses an optical element comprising a base section and a prism section. The base section is a transparent body formed in the shape of a flat plate. The prism section is formed on a surface of the base section. In a cross-section of the prism section along a predetermined direction, a first region, whose angle of inclination with respect to a surface opposite that surface is in the range of 0 degrees to 8 degrees, is continuous with a second region having a prism shape, and a proportion of the first region over the length in the predetermined direction is 60% or more, and less than 100%.

[0007] US Patent 2009 / 0161368A1 discloses a display comprising a light source for generating light, an optical waveguide for receiving and uniformly distributing the light in the direction of propagation by total internal reflection, and a matrix of image elements arranged on the top of the waveguide, wherein the image elements comprise electrically activated micromechanical actuators with optical properties for modulating the light for image generation.

[0008] WO 2017 / 077 934 A1 discloses a light guide and a virtual image display device. The light guide is equipped with: a coupling structure with a light-receiving surface that receives a light beam from a display element; and a light guide plate comprising a first light guide layer with a prismatic surface arranged to transmit a portion of the light beam entering and propagating through the coupling structure, and a second light guide layer covering the prismatic surface and having an exit surface from which the light beam transmitted through the prismatic surface exits. The refractive index of the coupling structure differs from the refractive index of the light guide plate. Summary

[0009] In the optical device described in JP 6 372 305 B2, the semi-transparent flat mirror consists of a vapor deposition metal film or a dielectric multilayer coating film. However, since the vapor deposition metal film has a high light absorption rate, if the semi-transparent flat mirror consists of a single-layer vapor deposition metal film, the loss of light reflected from the semi-transparent flat mirror increases. In this case, the view or scene perceived by the observer through the optical device is dark or darker.

[0010] The dielectric multilayer coating film exhibits a lower light absorption rate than the single-layer vapor deposition metal film. Therefore, if the semi-transparent flat mirror is made of a dielectric multilayer coating film, light loss due to the semi-transparent nature of the flat mirror can be prevented. However, the dielectric multilayer coating film requires more manufacturing steps than the vapor deposition metal film, which increases the manufacturing cost of the optical device. Since the reflectivity of the dielectric multilayer coating film changes depending on the angle of incidence and the wavelength of the light, the brightness and hue of the external scene change depending on the angle at which the observer views the first surface of the optical fiber.

[0011] The inventors of the present invention have arranged a flat section between the prisms and thus dispensed with the semi-transparent flat mirror according to JP 6 372 305 B2 in order to totally reflect the light from the outside scene that travels within the light guide. It should be noted that this configuration was created by the inventors and does not constitute a conventional technology.

[0012] However, as a result of detailed studies conducted by the inventors, it was discovered that such a configuration of the optical device presents the following problems. Specifically, if external light strikes the flat section at an angle symmetrical to the light from the external scene emitted from the optical device's exit surface towards the viewer's eyelids, and with respect to a normal of the flat section, the external light can be reflected by the flat section and reach the viewer's eyelids. Furthermore, the external light can propagate through the light guide from the flat section and then be emitted from another flat section, thus reaching the viewer's eyelids. In this case, the external light is superimposed on the light from the external scene emitted from the optical device's exit surface and is visually perceived by the viewer.

[0013] It is an object of the present invention to provide an optical device capable of improving the visibility of an image of an outdoor scene. This object is achieved by an optical device having the features of independent claim 1. The dependent claims are directed to advantageous embodiments of the invention.

[0014] To solve the above problem, an optical device according to a first aspect of the present invention comprises a light guide and a light-shielding section and is designed to display an image of an external scene of a blind spot area to a viewer when an obstacle is within the viewer's field of vision. The light guide has: an incident surface onto which light of an external scene coming from a blind spot area is incident; a first surface having several flat sections and several prism sections, wherein the light of the external scene incident from the incident surface first reaches the first surface; and a second surface arranged opposite the flat sections of the first surface.The light-shielding section is positioned on a surface of the optical fiber or at a location away from the optical fiber to block any external light entering the optical fiber. The flat sections of the first surface totally reflect the external light traveling within the optical fiber towards the second surface. The second surface totally reflects the external light reflected by the flat sections back towards the first surface. Each prism section has an exit surface for emitting outwards a portion of the external light incident at the incident surface and a portion of the external light reflected by the second surface, and an inclined surface that faces away from the viewer with respect to the exit surface.The light-shielding section has a first light-shielding section designed to block external light that would fall on the inclined surface, and a second light-shielding section designed to block external light that would fall on the flat section in a predetermined direction.In a cross-sectional view containing a normal to the exit surface and a normal to the flat section, θ is an angle formed between the normal to the flat section and a line connecting the center of a predetermined exit surface and the eye center of the viewer, L is a distance between the center of the predetermined exit surface and the eye center, DL is a distance between the eye center and an outer edge of an eyelid of the viewer opposite the light guide in a direction perpendicular to the line connecting the center of the predetermined exit surface and the eye center, and θmin is an angle formed by θ-tan. -1(DL / L) is represented, wherein a straight line A passes through a point where the exit surface and the inclined surface intersect, and the straight line A is incident on the flat section at an angle θmin with respect to the normal to the flat section, wherein a straight line B is parallel to the straight line A and is incident on a point ora meeting where the inclined surface and the flat section intersect, wherein the straight line A intersects the flat section at a point P1, wherein the straight line B intersects the flat section at a point P2, wherein the exit surface intersects the flat section at a point P3, wherein Fa is defined as a distance between point P1 and point P3, wherein Fb is defined as a distance between point P2 and point P3, where Fa < Fb is satisfied, and wherein the second light-shielding section is arranged such that it covers the straight line A and the straight line B.

[0015] Since the second light-shielding section is positioned to overlap straight lines A and B, any external light arriving at the flat section at an angle of incidence equal to or greater than that of straight line A is blocked by the second light-shielding section, preventing external light from being reflected through the flat section toward the viewer's eyelids. If the external light travels from the flat section into the light guide and is reflected by the second surface, it is prevented from being emitted from any other flat section toward the viewer's eyelids. The first light-shielding section prevents external light from propagating from the inclined surface into the light guide and from exiting the flat section or exit surface toward the viewer's eyelids.Therefore, it prevents external light from interfering with the image of the outside scene in the blind spot area displayed to the viewer. This optical device can thus clearly display the image of the outside scene in the blind spot area to the viewer and improve its visibility.

[0016] The reference numerals added to the components indicate an example of a correspondence between the components and special components in the embodiments described below. Brief description of the drawings Fig. Figure 1 is a schematic diagram showing an optical device according to a first embodiment, which is mounted on a device in which a viewpoint of an observer is fixed. Fig. Figure 2 is a schematic view of the optical device according to the first embodiment. Fig. Figure 3 is a cross-sectional view to illustrate optical paths of light from an outdoor scene and outdoor light in the optical device according to the first embodiment. Fig. 4 is a diagram from the perspective of direction IV in Fig. 2. Fig. Figure 5 is an enlarged view of area V of the Fig. 2. Fig. Figure 6 is a diagram to illustrate a positional relationship between the optical device and the eyelids of the viewer. Fig. Figure 7 is a cross-sectional view to illustrate optical paths of light from an outdoor scene and outdoor light in an optical device of a comparative example. Fig. Figure 8 is an enlarged view showing an optical device according to a second embodiment in accordance with Fig. 5 shows. Fig. Figure 9 is an enlarged view showing an optical device according to a third embodiment in accordance with Fig. 5 shows. Fig. Figure 10 is a schematic view of an optical device according to a further embodiment. Detailed description

[0017] In the following, embodiments of the present invention are described with reference to the drawings. In the following embodiments, the same or equivalent parts are designated by the same reference numerals, and their description is not repeated. First embodiment

[0018] An optical device according to a first embodiment is described with reference to the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. 6 described. As it is in Fig. As shown in Figure 1, the optical device 1 of the present embodiment is mounted on a device 11 in or on which a viewpoint of an observer 10 is fixed. In this embodiment, a vehicle is described as an example of the device 11. The vehicle has a front pillar 12 as an obstacle within the front field of vision of the observer 10 (for example, a driver). The optical device 1 is arranged on the inside of the front pillar 12 of the vehicle. The optical device 1 serves as a blind spot aid that can display an image of an external scene of an area of ​​a blind spot 13 for the observer 10. The area of ​​the blind spot 13 is not directly viewed by the observer 10 due to the front pillar 12.

[0019] As it is in the Fig. 2, Fig. 3 to Fig. As shown in Figure 4, the optical device 1 includes a light guide 2 and a light-shielding section 51, 52. Fig. 2 and Fig. Figure 3 shows cross-sections of the optical device 1, but the diagonal dashed lines have been omitted to better illustrate the details. This also applies to the Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9 to Fig. 10. In Fig. 4, coming from direction IV of the Fig. In section 2, the light shielding section 51, 52 is shown with diagonal dashed lines to distinguish it from the light guide 2, even though it is not a cross-section.

[0020] As it is in the Fig. 2 and Fig. As shown in Figure 3, the optical fiber 2 has an incident surface 2a onto which light coming from the area of ​​the blind spot 13 (hereinafter referred to as "outside scene light LV") falls. The optical fiber 2 has a first surface 2b, which is the first surface reached by the outside scene light LV incident from the incident surface 2a. The optical fiber 2 has a second surface 2c, which is opposite the first surface 2b, and a third surface 2d, which is opposite the incident surface 2a and connects the first surface 2b and the second surface 2c. The first surface 2b of the optical fiber 2 has flat sections 3 and prism sections 4. The flat sections 3 and the prism sections 4 are arranged alternately on the first surface 2b.The prism section 4 has an exit surface 4a facing the viewer 10 and an inclined surface 4b opposite the exit surface 4a, such that it does not face the viewer 10 with respect to the external scene light LV entering the incident surface 2a. For the sake of simplicity, the flat sections 3 and the prism sections 4 are shown larger in each figure than they actually are.

[0021] The optical fiber 2 consists of a transparent material, for example a resin material such as polyethylene terephthalate, polycarbonate, polyethylene, acrylic or glass. Fig. 3 are examples LV1, LV2 and LV3 of the outdoor scene light LV indicated with bold arrows, which enter the incidence surface 2a of the light guide 2 from the area of ​​the blind spot 13, propagate within the light guide 2 and are emitted from the exit surface 4a in the direction of the viewer 10.

[0022] As it is in Fig. As shown in Figure 3, the flat sections 3 of the first surface 2b reflect the outside scene light LV, which propagates within the light guide 2, completely towards the second surface 2c. The second surface 2c is arranged opposite the flat sections 3 and reflects the outside scene light LV, which is reflected by the flat sections 3, completely towards the first surface 2b. The exit surface 4a of the prism section 4 emits outwards a portion of the outside scene light LV incident from the incident surface 2a and a portion of the outside scene light LV reflected by the second surface 2c.

[0023] In particular, the optical fiber 2 is configured as follows. First, θ1 is defined as the angle between the external scene light LV, which is incident on the incident surface 2a from the outside of the optical fiber 2, and a normal to the flat section 3. Furthermore, Φ is defined as the angle of incidence between the external scene light LV, which propagates inside the optical fiber 2, and the normal to the flat section 3. Here, the optical fiber 2 is configured such that it satisfies the relationship θ1 < Φ (Formula 1).

[0024] As it is in Fig. As shown in Figure 3, the outside scene light LV, which propagates within the light guide 2, has an angle of incidence Φ with respect to the flat section 3, and the outside scene light LV, which is reflected by the flat section 3, also has an angle of incidence Φ with respect to the second surface 2c. n1 represents the refractive index of the light guide 2, and n2 represents the refractive index of the medium that contacts the light guide 2. In this embodiment, the medium that contacts the light guide 2 is air, and its refractive index n2 is equal to 1. The light guide 2 is configured such that it satisfies the relationship sinΦ > n2 / n1 (Formula 2).

[0025] This means that the angles of the incident surface 2a, the flat section 3, and the second surface 2c, as well as the material of the light guide 2, are configured such that the angle of incidence Φ of the external scene light LV with respect to the flat section 3 and the angle of incidence Φ of the external scene light LV reflected by the flat section 3 with respect to the second surface 2c are greater than a critical angle. With this configuration, the light guide 2 does not require a semi-transparent mirror or any other reflector, and the external scene light LV incident from the incident surface 2a undergoes total internal reflection by the flat sections 3 and the second surface 2c and propagates to the external surface 4a, where it is emitted to the outside.

[0026] Since, in the present embodiment, the flat sections 3 and the second surface 2c are parallel to each other, the angle of incidence Φ of the external scene light LV with respect to the flat section 3 and the angle of incidence Φ of the external scene light LV with respect to the second surface 2c are equal. Note that the flat section 3 and the second surface 2c do not have to be parallel to each other while the relationship of formula 2 is satisfied.

[0027] As it is in Fig. As shown in Figure 3, with the configuration above, for example, the outside scene light LV, which comes from the area of ​​the blind spot 13, enters the incident surface 2a at a predetermined angle of incidence θ1, is refracted, and propagates to the second surface 2b. Of the outside scene light LV incident from the incident surface 2a, the outside scene light LV2, which reaches the exit surface 4a of the prism section 4 of the first surface 2b, is emitted earliest from the exit surface 4a to the outside.

[0028] The external scene light LV, incident at the incident surface 2a, is emitted by the external scene lights LV1 and LV3 to the flat section 3 of the first surface 2b, where it undergoes total internal reflection at the interface with the outside. The external scene lights LV1 and LV3 propagate within the light guide 2 towards the second surface 2c without being emitted to the outside. Having reached the second surface 2c, the external scene lights LV1 and LV3 undergo another total internal reflection at the interface with the outside and propagate within the light guide 2 towards the first surface 2b. A portion of the external scene light LV1 is emitted from the exit surface 4a by one of the prism sections 4 at a predetermined emission angle θ2, and the remaining external scene light LV3 undergoes total internal reflection through the flat section 3.

[0029] The exterior scene light LV3, which does not reach prism section 4 after being repeatedly reflected by the flat section 3 and the second surface 2c, finally reaches the third surface 2d and is emitted to the outside as afterglow. The emission of the afterglow can be prevented by providing a light-absorbing film (not shown) or similar material on the third surface 2d.

[0030] In this way, the exterior scene lights LV1 and LV3 are alternately reflected by the flat section 3 and the second surface 2c and move gradually from the incident surface 2a in the direction in which the prism sections 4 are arranged. Part of the exterior scene light LV is emitted by the prism sections 4 towards the viewer 10. As a result, the area in which the viewer 10 can visually perceive the exterior scene lights LV1 and LV2 emitted by the light guide 2 can be enlarged.

[0031] The “angle of incidence θ1” refers to the angle formed by the direction of incidence of the external scene light LV on the incidence surface 2a and the normal to the flat section 3. The “angle of emission θ2” refers to the angle formed by the direction of propagation of the external scene light LV, emitted from the exit surface 4a, and the normal to the flat section 3. Furthermore, in this embodiment, the flat sections 3 and the second surface 2c are parallel to each other, and the incidence surface 2a and the exit surface 4a are also parallel to each other. As shown in Fig. As shown in Figure 3, the angle ψ formed between the incident surface 2a and the normal to the flat section 3 is the same as the angle ψ formed between the exit surface 4a and the normal to the flat section 3. Therefore, the angle of incidence θ1 of the outside scene light LV incident on the incident surface 2a is the same as the angle of emission θ2 of the outside scene light LV emitted from the exit surface 4a.

[0032] The light-shielding section 51, 52 comprises a first light-shielding section 51, which is arranged on the inclined surface 4b of the prism section 4, and a second light-shielding section 52, which is arranged at a position facing the flat section 3. A material for the first light-shielding section 51 and the second light-shielding section 52 is, for example, a light-absorbing material, a light-diffusion material, a retroreflective material, or the like. The first light-shielding section 51 is arranged on each of the inclined surfaces 4b of the prism sections 4. The first light-shielding section 51 is formed on the surface of the inclined surface 4b of the prism section 4 by any process such as printing or vapor deposition.Therefore, the first light-shielding section 51 can prevent external light LD coming from all directions from entering the inclined surface 4b of the prism section 4.

[0033] The second light-shielding section 52 is arranged for each of the flat sections 3 in a position facing the flat sections 3. As shown in the Fig. 2 and Fig. As shown in Figure 3, the second light-shielding section 52 is located at a position remote from, or separate from, the flat section 3 and does not contact it. Since the flat section 3 is in contact with air, the conditions for total internal reflection at the flat section 3 are maintained. As shown in Figure 3, the second light-shielding section 52 is located at a position remote from, or separate from, the flat section 3 and does not contact it. Fig. As shown in Figure 4, one end and the other end of the second light-shielding section 52 are fixed to respective supports 7 and 8.

[0034] As it is in Fig. As shown in Figure 3, the second light-shielding section 52 is positioned to block the outside light LD arriving at the flat section 3 in a predetermined direction (hereinafter referred to as "predetermined outside light LD"). When the predetermined outside light LD is reflected through the flat section 3 after reaching it from various directions, the reflected light reaches the eyelids of the viewer 10. When the predetermined outside light LD propagates within the light guide 2 from the flat section 3, the predetermined outside light LD is reflected through the second surface 2c and then reaches another flat section 3, from which it is emitted to reach the eyelids of the viewer 10.

[0035] When the optical device 1 is mounted on a vehicle, the eyelids are located in an eye area of ​​the right eye and the left eye of the viewer 10 (i.e. the driver), which is represented by an oval in the side view and the top view, as defined, for example, by the Japanese industrial standard D0021:1998 or ISO 4513:2010.

[0036] As it is in Fig. As shown in Figure 5, the second light-shielding section 52 is arranged such that it overlaps with or covers the straight line A and the straight line B. This allows the second light-shielding section 52 to prevent the predetermined external light LD from entering the flat section 3. Furthermore, the second light-shielding section 52 is located in an area between the flat section 3 and the straight line C, as shown in Figure 5. Fig. Figure 5 shows that the second light-shielding section 52 is positioned such that it does not block the path of the outside scene light LV, which is emitted from the exit surfaces 4a towards the eyelids of the viewer 10. The technical significance of the arrangement of the second light-shielding section 52 at the position defined by the straight lines A, B, and C is described below.

[0037] Fig. Figure 6 is a diagram showing the positional relationship between the optical device 1 and the eyelids 14 of the viewer 10. Since the optical device 1 of the present embodiment is mounted on the “device 11 in which the viewpoint of the viewer 10 is fixed”, the positional relationship between the optical device 1 and the eyelids 14 of the viewer 10 is unique or unambiguously defined.

[0038] As it is in Fig. As shown in Figure 6, L represents a distance between the center of a predetermined exit surface 4a (for example, the exit surface 4a closest to the incidence surface 2a) of the optical device 1 and the eye center 15 of the observer 10. The eye center 15 is a point equidistant from the center of the left eyelid 14a and the center of the right eyelid 14b. In general, the distance L is, for example, approximately 650 to 700 mm.

[0039] DL represents a distance between the eye center 15 of the observer 10 and an outer edge of the eyelids 14a of the observer 10 away from the light guide 2 in a direction perpendicular to a line connecting the center of the predetermined exit surface 4a and the eye center 15. In general, the distance DL is, for example, 75 mm.

[0040] DR represents a distance between the eye center 15 of the observer 10 and an outer edge of the eyelids 14b of the observer 10 adjacent to the light guide 2 in the direction perpendicular to a line connecting the center of the predetermined exit surface 4a and the eye center 15. In general, the distance DR is, for example, 75 mm.

[0041] Note that L, DL and DR are not limited to the exemplary values, but are determined depending on the device 11 (in this embodiment the vehicle type) in which the optical device 1 is or will be mounted.

[0042] The angle θ is defined between the normal to the flat section 3 and the line connecting the center of the predetermined exit surface 4a and the eye point 15 of the observer 10. The angle θmin is given by the formula θ-tan -1 (DL / L) represents the angle θmax. The angle θmax is given by the formula θ+tan. -1(DR / L) represents. The light guide 2 is designed such that the emission angle θ2 of the external scene light LV, which enters the incident surface 2a from the area of ​​the blind spot 13 and propagates through the light guide 2 to be emitted from the external surface 4a, is set in a range between θmax and θmin.

[0043] As it is in Fig. As shown in Figure 5, the straight line A is defined such that it passes through point 4c, where the exit surface 4a and the inclined surface 4b intersect, and is symmetrically perpendicular to the flat section 3 at an angle θmin with respect to the normal to the flat section 3. The straight line B is defined such that it is parallel to the straight line A and is perpendicular to point P2, where the inclined surface 4b and the flat section 3 intersect.

[0044] The straight line A and the flat section 3 intersect at point P1. The straight line B and the flat section 3 intersect at point P2. The exit surface 4a and the flat section 3 intersect at point P3. Point P2 can also be defined as the point where the inclined surface 4b and the flat section 3 intersect. The distance Fa is defined between point P1 and point P3. The distance Fb is defined between point P2 and point P3. The distance Fb is, for example, approximately 1 mm.

[0045] Here, the optical device 1 of this embodiment exhibits the relationship Fa < Fb. That is, the point P1 where the straight line A intersects the flat section 3 lies in the middle of the flat section 3. The predetermined external light LD propagates in the area between the straight lines A and B, thus preventing it from reaching the eyelids 14 of the viewer 10 after reflection and penetration of the flat section 3 upon arrival from different directions. Therefore, the second light-shielding section 52 is arranged such that it covers the straight lines A and B. In other words, the second light-shielding section 52 is arranged to shield the area between the straight lines A and B.

[0046] If the second light-shielding section 52 is arranged such that it covers the straight lines A and B or the area between them, the second light-shielding section 52 can block the predetermined external light LD incident on the flat section 3 in a predetermined direction. In other words, the second light-shielding section 52 can prevent the predetermined external light LD from entering the flat section 3. The predetermined external light LD incident on the area opposite to the incident surface 2a with respect to the straight line B is prevented by the first light-shielding section 51 from entering the light guide 2.

[0047] The external scene light LV, emitted from the exit surface 4a and directed towards the eyelids 14 of the viewer 10, propagates through the area opposite to the flat section 3 with respect to the straight line C. Therefore, the second light-shielding section 52 is located in an area between the flat section 3 and the straight line C. This makes it possible to position the second light-shielding section 52 in a location that does not obstruct the path of the external scene light LV, which is emitted from the exit surfaces 4a towards the eyelids 14 of the viewer 10.

[0048] The second light-shielding section 52 can have any shape, arrangement position and arrangement angle, as long as it covers the straight lines A and B or the area between them and is located in the area between the flat section 3 and the straight line C.

[0049] An optical device 100 of a comparative example is described for comparison with the optical device 1 of the first embodiment. Note that the optical device 100 of the comparative example was produced by the applicant of the present invention and does not represent prior art.

[0050] As it is in Fig. As shown in Figure 7, the optical device 100 of the comparative example has the same configuration as the optical device 1 of the first embodiment, except that the second light-shielding section 52 is not present. That is, the optical device 100 of the comparative example contains the first light-shielding section 51, but not the second light-shielding section 52. Therefore, in the optical device 100 of the comparative example, the predetermined external light LD falls on the flat section 3. As indicated by an arrow LD4 in Fig. As indicated, for example, in Figure 7, a portion of the external light LD4 of the predetermined external light LD, incident on the flat section 3, is reflected by the flat section 3 and reaches the eyelids 14 of the viewer 10. As indicated by the arrow LD5, another portion of the external light LD5 of the predetermined external light LD, incident on the flat section 3, propagates from the flat section 3 within the light guide 2, is reflected by the second surface 2c, and reaches the eyelids 14 of the viewer 10 from another flat section 3. In this case, the viewer 10 sees the external light LD4, LD5 superimposed on the external scene light LV2, LV1 emitted by the optical device 100 of the comparison example, thus reducing the visibility of the external scene image.

[0051] In comparison to the optical device 100 of the comparative example, the optical device 1 of the present embodiment has the following effects. (1) The optical device 1 of the first embodiment comprises the first light-shielding section 51 for blocking the external light LD incident on the inclined surface 4b, and the second light-shielding section 52 for blocking the predetermined external light LD incident on the flat section 3 in a predetermined direction. The second light-shielding section 52 is arranged such that it covers the straight line A and the straight line B, or the area between them.

[0052] Accordingly, the second light-shielding section 52 prevents the predetermined external light LD from being reflected through the flat section 3 towards the eyelids 14 of the viewer 10. It also prevents the predetermined external light LD from propagating from the flat section 3 into the light guide 2, being reflected through the second surface 2c, and then exiting from another flat section 3 towards the eyelids 14 of the viewer 10. The first light-shielding section 51 also prevents the predetermined external light LD from propagating from the inclined surface 4b into the light guide 2 and exiting from the flat section 3 or the exit surface 4a towards the eyelids 14 of the viewer 10. Therefore, it prevents the predetermined external light LD from being superimposed on the image of the external scene of the blind spot area 13 displayed to the viewer 10.Therefore, the optical device 1 can clearly display the image of the outside scene of the area of ​​the blind spot 13 to the viewer 10 and increase its visibility.

[0053] Furthermore, in the first embodiment, the straight line A is defined such that it passes through the point 4c where the outer surface 4a and the inclined surface 4b intersect, and is defined such that it falls onto the flat section 3 at an angle θmin symmetrically with respect to the normal to the flat section 3. The second light-shielding section 52 is arranged such that it covers the straight line A. This allows the second light-shielding section 52 to block the external light LD arriving at the flat section 3 at an angle of incidence equal to or greater than that of the straight line A. Therefore, the second light-shielding section 52 can prevent the external light LD from reaching the eyelids 14 of the observer 10.

[0054] Since in the first embodiment the second light-shielding section 52 is arranged such that it overlaps with the straight lines A and B, the second light-shielding section 52 can be arranged at a required location to prevent the predetermined external light LD from reaching the viewer 10.

[0055] (2) In the first embodiment, the second light-shielding section 52 is arranged in an area between the flat section 3 and the straight line C. Accordingly, the second light-shielding section 52 does not block the path of the outside scene light LV emitted from the exit surfaces 4a towards the eyelids 14 of the viewer 10. Therefore, the optical device 1 can clearly display the image of the outside scene in the area of ​​the blind spot 13 for the viewer 10 and improve its visibility.

[0056] (3) In the first embodiment, the second light-shielding section 52 and the flat section 3 do not contact each other, and the flat section 3 contacts the air. Accordingly, the condition of total internal reflection can be maintained in the flat section 3 of the light guide 2, and the outside scene light LV can propagate within the light guide 2.

[0057] (4) In the first embodiment, the second light-shielding section 52 is arranged such that it does not cover or obstruct the area through which the external scene light LV, emitted from the exit surface 4a towards the eyelids 14 of the viewer 10, passes. Accordingly, the second light-shielding section 52 does not block the path of the external scene light LV emitted from the exit surfaces 4a towards the eyelids 14 of the viewer 10. Therefore, the optical device 1 can clearly display the image of the external scene in the area of ​​the blind spot 13 for the viewer 10 and increase its visibility.

[0058] (5) In the first embodiment, the second light-shielding section 52 comprises a light-absorbing material, a light-diffusion material, or a retroreflective material. Thus, the material forming the second light-shielding section 52 is only an example.

[0059] (6) In the first embodiment, the outdoor scene light LV propagating within the light guide 2 has an angle of incidence Φ with respect to the flat section 3, and the outdoor scene light LV reflected by the flat section 3 has an angle of incidence Φ with respect to the second surface 2c. The refractive index of the light guide 2 is defined as n1, and the refractive index of the medium in contact with the light guide 2 is defined as n2. Here, the light guide 2 satisfies the relationship sinΦ > n2 / n1. Accordingly, the flat section 3 can totally reflect the outdoor scene light LV towards the second surface 2c. Furthermore, the second surface 2c can totally reflect the outdoor scene light LV reflected by the flat section 3 towards the first surface 2b.Therefore, the optical fiber 2 can satisfy total internal reflection conditions with respect to the flat section 3 and the second surface 2c without the need for a semi-transparent mirror or any other mirror.

[0060] (7) In the first embodiment, the angle θ1 is defined between the external scene light LV, which is incident from the outside of the light guide 2 onto the incident surface 2a, and the normal to the flat section 3, and the external scene light LV, which propagates inside the light guide 2, has an angle of incidence Φ with respect to the flat section 3. The light guide 2 is configured such that it satisfies the relationship θ1 < Φ. Accordingly, the angle of the incident surface 2a is set such that the external scene light LV is totally reflected by the flat section 3 of the light guide 2. Second embodiment

[0061] The second embodiment is described with reference to Fig. The second embodiment differs from the first embodiment in that the arrangement of the second light-shielding section 52 is different and a total reflection retention section 6 is added. The remaining configuration is the same as in the first embodiment, and mainly only the parts that differ from the first embodiment are described.

[0062] As it is in Fig. As shown in Figure 8, in the second embodiment, the second light-shielding section 52 contacts the flat section 3. The second light-shielding section 52 is arranged for each of the flat sections 3. The material used for the second light-shielding section 52 can be, for example, a light-absorbing material, a light-diffusion material, a retroreflective material, or something similar to that used in the first embodiment. The second light-shielding section 52 can be formed on the surface of the flat section 3 by any process, such as printing or vapor deposition.

[0063] The straight lines A, B and C, which are in Fig. The second light-shielding section 52, shown in Figure 8, is the same as that described in the first embodiment. The second light-shielding section 52 is arranged such that it covers both straight line A and straight line B. In other words, the second light-shielding section 52 is arranged such that it covers at least one area between straight lines A and B on the flat section 3. As a result, the second light-shielding section 52 can block the predetermined external light LD incident on the flat section 3 in the predetermined direction (that is, the external light LD arriving at the flat section 3, being reflected by and entering the flat section 3, and ultimately reaching the eyelids 14 of the observer 10).

[0064] Since the second light-shielding section 52 contacts the flat section 3, the second light-shielding section 52 is naturally located in an area between the flat section 3 and the straight line C. Therefore, the second light-shielding section 52 does not obstruct the path of the outside scene light LV, which is emitted from the exit surface 4a towards the eyelids 14 of the viewer 10.

[0065] Furthermore, in the second embodiment, the total reflection retention section 6 is arranged within the optical fiber 2. The total reflection retention section 6 is positioned within the optical fiber 2 at a location corresponding to the second light-shielding section 52, between the second surface 2c and the flat section 3. The total reflection retention section 6 is dimensioned such that it has a size equal to or greater than that of the second light-shielding section 52. A surface of the total reflection retention section 6 adjacent to the second surface 2c is a plane parallel to the flat section 3. Additionally, the refractive index of the total reflection retention section 6 is less than the internal refractive index of the optical fiber 2, and the difference between the refractive index of the total reflection retention section 6 and the internal refractive index of the optical fiber 2 is 0.11 or greater.Furthermore, in the second embodiment, the angle and material of each part of the light guide 2 are designed such that the relationship of formula 2 given above is satisfied. In the second embodiment, with respect to formula 2, the total reflection retaining section 6 is the medium that contacts a part of the light guide 2. Therefore, in the second embodiment as well, the total reflection condition can be maintained at the interface between the light guide 2 and the total reflection retaining section 6, and the outside scene light LV can propagate within the light guide 2. As described in . Fig. As shown in Figure 8, the outside scene light LV, which propagates within the light guide 2, is totally reflected at the surface of the total reflection holding section 6 adjacent to the second surface 2c.

[0066] The total internal reflection retention section 6 is, for example, formed from an air layer. The following method is conceivable as a method for manufacturing the total internal reflection retention section 6. In the manufacturing process, for example, the material of the optical fiber 2 is assembled from several elements, and some of these elements are formed with a recess to create the total internal reflection retention section 6, and then the elements are joined together. Thus, it is possible to form an air layer as the total internal reflection retention section 6 within the optical fiber 2.

[0067] The optical device 1 of the second embodiment can achieve the same effects as the first embodiment, and can also achieve the following effects.

[0068] In the second embodiment, the second light-shielding section 52 and the flat section 3 are in contact with each other. Furthermore, the total internal reflection retention section 6 is arranged within the light guide 2 at a position corresponding to the second light-shielding section 52, between the second surface 2c and the flat section 3. The refractive index of the total internal reflection retention section 6 is smaller than the internal refractive index of the light guide 2, and the difference between the refractive index of the total internal reflection retention section 6 and the internal refractive index of the light guide 2 is 0.11 or greater. Accordingly, the total internal reflection condition can be maintained at the interface between the light guide 2 and the total internal reflection retention section 6, and the external scene light LV can propagate within the light guide 2. Third embodiment

[0069] The third embodiment is described with reference to Fig. 9 described. In the third embodiment, the configurations of the second light-shielding section 52 and the total reflection retention section 6 differ from those of the second embodiment. The main focus is on describing the parts that differ from the first embodiment.

[0070] As it is in Fig. As shown in Figure 9, in the third embodiment, the flat section 3 of the light guide 2 and the total reflection retaining section 61 are in contact with each other. The second light-shielding section 52 is arranged on the total reflection retaining section 61 opposite, or in the opposite direction to, the light guide 2. The total reflection retaining section 61 and the second light-shielding section 52 are present for each of the flat sections 3. The material of the second light-shielding section 52 can be, for example, a light-absorbing material, a light-diffusion material, a retroreflective material, or something similar to that used in the first embodiment. The second light-shielding section 52 can have direct contact with the total reflection retaining section 61, or another medium (for example, an adhesive) can be located between the second light-shielding section 52 and the total reflection retaining section 61.

[0071] The straight lines A, B and C, which are in Fig. The second light-shielding section 52, shown in Figure 9, is the same as that described in the first embodiment. The second light-shielding section 52 is arranged to cover both straight line A and straight line B. In other words, the second light-shielding section 52 is arranged to cover at least the area between straight lines A and B in the flat section 3. As a result, the second light-shielding section 52 can block the external light LD incident on the flat section 3 in a predetermined direction (that is, the external light LD arriving at the flat section 3, being reflected by the flat section 3, and entering the flat section 3 to eventually reach the eyelids 14 of the observer 10).

[0072] Furthermore, the second light-shielding section 52 is located in an area between the flat section 3 and the straight line C. Therefore, the second light-shielding section 52 does not interfere with the path of the external scene light LV, which is emitted from the exit surface 4a towards the eyelids 14 of the viewer 10.

[0073] As described above, the total reflection retention section 61 is arranged between the flat section 3 of the optical fiber 2 and the second light-shielding section 52. The flat section 3 of the optical fiber 2 and the total reflection retention section 61 have surface contact (i.e., close contact). Furthermore, the refractive index of the total reflection retention section 61 is lower than the internal refractive index of the optical fiber 2, and the difference between the refractive index of the total reflection retention section 61 and the internal refractive index of the optical fiber 2 is 0.11 or greater. The total reflection retention section 61 is made, for example, of magnesium fluoride. In the third embodiment, the angle and material of each respective part of the optical fiber 2 are designed such that the relationship of the formula 2 above is satisfied.In the third embodiment, with respect to formula 2, the total reflection retention section 61 is the medium that contacts a portion of the flat section 3 of the light guide 2. Therefore, even in the third embodiment, the total reflection condition can be maintained at the surface between the flat section 3 of the light guide 2 and the total reflection retention section 61, and the external scene light LV can propagate within the light guide 2. As shown in . Fig. As shown in Figure 9, the outside scene light LV, which propagates within the light guide 2, is totally reflected at the interface between the flat section 3 and the total reflection holding section 61.

[0074] The optical device 1 of the third embodiment can achieve the same effects as the first embodiment and also the following effects.

[0075] In the third embodiment, the total internal reflection retention section 61 is positioned between the second light-shielding section 52 and the flat section 3. The total internal reflection retention section 61 and the flat section 3 are in contact with each other. The refractive index of the total internal reflection retention section 61 is smaller than the internal refractive index of the light guide 2, and the difference between the refractive index of the total internal reflection retention section 61 and the internal refractive index of the light guide 2 is 0.11 or greater. Because the flat section 3 and the total internal reflection retention section 61 are in contact with each other, the total internal reflection condition can be maintained in the flat section 3, and the outside scene light LV can propagate within the light guide 2.

[0076] Other embodiments (1) In each embodiment, a vehicle is described as an example of the “device 11 in which the viewpoint of the observer 10 is fixed” in which the device 1 is mounted. The optical device 1 can be installed in various devices 11 in which the viewpoint of the observer 10 is fixed. (2) In each embodiment, the prism section 4 is triangular, but is not limited to this shape and can have any shape such as a trapezoid. (3) In each embodiment, the incidence surface 2a is formed on the surface connecting the first surface 2b and the second surface 2c. As shown in Fig.As shown in Figure 10, the incident surface 2a can alternatively be formed by a part of the second surface 2c that is in a prism shape. In this case, the angle ψ formed between the normal to the flat section 3 and the incident surface 2a formed on the prism on the second surface 2c is the same as the angle ψ formed between the exit surface 4a and the normal to the flat section 3. (4) In each embodiment, the second light-shielding section 52 is arranged for part of the flat section 3 such that it overlaps with straight line A and straight line B. However, the second light-shielding section 52 can also be arranged such that it covers the entire flat section 3. (5) In each embodiment, the right front pillar (that is, the right A-pillar) is described by way of example as an obstacle present within the view in front of the observer 10. However, the obstacle may also be the left A-pillar, the B-pillar, the C-pillar or the D-pillar when the optical device is mounted on the vehicle.

[0077] The present invention is not limited to the embodiments described above, but can be suitably modified within the scope of the claims. The embodiments described above are not independent of one another and can be suitably combined, unless the combination is obviously impossible. Furthermore, it need not be said that in each of the embodiments described above, components of an embodiment are not necessarily essential, except in cases where the components are specifically specified as essential components, in cases where the components are clearly evident in principle as essential components, and similar cases.In each of the embodiments described above, where numerical values ​​such as the number, a numerical value, a quantity, a range, and the like of the components of the embodiment are mentioned, the present invention is not limited in principle to that specific number, except where the numerical values ​​are expressly deemed essential. Where, in the respective embodiments described above, the shape of an element or the positional relationship between elements is mentioned, the present invention is not limited to that specific shape or positional relationship unless specifically stated otherwise or the present invention is limited in principle to that specific shape or positional relationship.

Claims

Optical device designed to display an image of an outside scene of an area of ​​a blind spot (13) to a viewer (10) when an obstacle (12) is within the viewer's field of vision, the optical device comprising: a light guide (2) with an incident surface (2a) onto which outside scene light (LV) coming from the area of ​​the blind spot (13) is incident; a first surface (2b) having several flat sections (3) and several prism sections (4), wherein the outside scene light incident from the incident surface first reaches the first surface; and a second surface (2c) arranged opposite the flat sections of the first surface; wherein a light-shielding section (51, 52) is arranged on a surface of the light guide or at a position away from the light guide to block any outside light (LD) that would enter the light guide.wherein the flat sections of the first surface totally reflect the outside scene light propagating within the light guide towards the second surface, the second surface totally reflects the outside scene light reflected by the flat sections towards the first surface, each prism section has an exit surface (4a) for emitting outwards part of the outside scene light incident from the incident surface and part of the outside scene light reflected by the second surface, and an inclined surface (4b) arranged opposite to the viewer with respect to the exit surface, the light-shielding section has a first light-shielding section (51) designed to block outside light incident on the inclined surface, and a second light-shielding section (52) designed to block outside light incident on the flat section in a predetermined direction,to block, in a cross-sectional view containing a normal to the exit surface and a normal to the flat section, θ is an angle formed between the normal to the flat section and a line connecting a center of a predetermined exit surface and the eye point center (15) of the viewer, L is a distance between the center of the predetermined exit surface and the eye point center, DL is a distance between the eye point center and an outer edge of the eyelids (14) of the viewer from the light guide in a direction perpendicular to the line connecting the center of the predetermined exit surface and the eye point center, θmin is an angle represented by θ-tan-1(DL / L), a straight line A passes through a point (4c) where the exit surface and the inclined surface intersect,and the straight line A falls on the flat section at an angle θmin symmetrically with respect to the normal to the flat section, a straight line B runs parallel to the straight line A and falls on a point where the inclined surface and the flat section intersect, the straight line A intersects the flat section at a point P1, the straight line B intersects the flat section at a point P2, the exit surface intersects the flat section at a point P3, a distance Fa is defined between point P1 and point P3, a distance Fb is defined between point P2 and point P3, Fa < Fb is satisfied, and the second light-shielding section is arranged such that it covers the straight line A and the straight line B. Optical device according to claim 1, wherein DR is a distance between the eye center and an outer edge of the eyelids of the viewer adjacent to the light guide in the direction perpendicular to the line connecting the center of the predetermined exit surface and the eye center, θmax is an angle represented by θ+tan-1(DR / L), a straight line C passes through an intersection between the exit surface and the flat section and is incident on the flat section at the angle θmax with respect to the normal to the flat section, and the second light-shielding section is arranged in a region between the flat section and the straight line C. Optical device according to claim 1 or 2, wherein the second light-shielding section and the flat section do not contact each other and the flat section contacts air. Optical device according to claim 1 or 2, wherein the second light-shielding section and the flat section are in contact with each other, a total reflection retention section (6) is arranged at a position corresponding to the second light-shielding section within the light guide between the second surface and the flat section, a refractive index of the total reflection retention section is less than an internal refractive index of the light guide, and a difference between the refractive index of the total reflection retention section and the internal refractive index of the light guide is equal to or greater than 0.

11. Optical device according to claim 1 or 2, wherein a total reflection retention section (61) is arranged between the second light-shielding section and the flat section, the flat section and the total reflection retention section are in surface contact with each other, a refractive index of the total reflection retention section is less than an internal refractive index of the optical fiber, and a difference between the refractive index of the total reflection retention section and the internal refractive index of the optical fiber is equal to or greater than 0.

11. Optical device according to one of claims 1 to 5, wherein the second light-shielding section is arranged such that it does not cover an area through which an external scene light, emitted from the exit surface towards the eyelids of the viewer, passes. Optical device according to any one of claims 1 to 6, wherein the second light-shielding section comprises a light-absorbing material, a light-diffusion material and / or a retroreflective material. Optical device according to any one of claims 1 to 7, wherein the outside scene light propagating within the light guide has an angle of incidence Φ with respect to the flat section, and the outside scene light reflected through the flat section has an angle of incidence Φ with respect to the second surface, n1 is a refractive index of the light guide, n2 is a refractive index of a medium contacting the light guide, and the light guide is designed such that it satisfies the relationship sinΦ > n2 / n1. Optical device according to any one of claims 1 to 8, wherein θ1 is an angle formed between the external scene light incident on the incident surface from the outside of the light guide and the normal to the flat section, Φ is an angle of incidence of the external scene light propagating inside the light guide with respect to the normal to the flat section, and the light guide is designed such that it satisfies the relationship θ1 < Φ.

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