Optical member

Abstract

To provide an optical member capable of obtaining a wider visual field in a dead angle area even without increasing the size of a light guide.SOLUTION: A light guide 2 includes: a curved incident surface 2a irradiated with external light; an emission part 2b including a plurality of projection-shaped prism parts 3 and a plurality of flat parts 4 having a flat surface and adjacent to the incident surface 2a; and first and second inclined planes 2c and 2d facing the emission part 2b. The incident surface 2a is a curved surface having the center concaved more than the end part; when using a plane parallel to one virtual plane formed of the plurality of flat parts 4 as a parallel plane and using an angle formed between each surface of the light guide 2 and the parallel plane as an inclination angle, the first inclined surface 2c has the same inclination angle as the second inclined surface or an inclination angle different from that of the second inclined surface; and the first and second inclined surfaces 2c and 2d adjacent to each other are not parallel to the flat parts 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an optical member that internally reflects a portion of light incident from an incident surface and emits the incident light and its reflected light to the outside from a surface different from the incident surface. [Background technology]

[0002] Conventionally, an optical element of this type that is attached to a light-blocking shield and enables a user to view a blind spot caused by the shield is disclosed, for example, in Patent Document 1. The optical element disclosed in Patent Document 1 includes a translucent light guide, a semi-transmissive reflective surface that transmits / reflects a portion of the light incident from the light entrance surface of the light guide, a plurality of prisms that emit the light transmitted through the semi-transmissive reflective surface to the outside, and a reflective surface facing the semi-transmissive reflective surface that totally reflects the light reflected by the semi-transmissive reflective surface. This optical element guides a portion of the light incident from the light entrance surface by repeatedly reflecting it between the semi-transmissive reflective surface and the reflective surface, and emits a portion of the incident light to the outside from an exit portion composed of the plurality of prisms, thereby allowing a user standing on the side of the exit portion to view an outside view in the blind spot caused by the shield. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-013693 Summary of the Invention [Problem to be solved by the invention]

[0004] The optical element described in Patent Document 1 has a smaller portion protruding from the shielding body than a blind spot auxiliary device such as a reflector attached to a shielding body such as a wall, and is therefore easier to mount. Also, from the perspective of ensuring a wider field of view in the blind spot area, this optical element has a configuration in which the entrance surface of the light guide constitutes a single prism that is larger than the prism that constitutes the exit part, thereby increasing the area of ​​incidence of external light on the entrance surface.

[0005] However, in order to ensure a wider field of view in the blind spot area, it is necessary to increase the area of ​​the incident surface of this optical element, but in this case, the opposing distance between the semi-transmissive reflective surface and the reflective surface becomes larger, which increases the thickness of the light guide and makes the light guide larger. If the light guide becomes larger, the optical element becomes heavier, which reduces the mountability on the shielding body, and there is a concern that it will become difficult to manufacture, or even if it can be manufactured, the manufacturing cost will increase.

[0006] In view of the above, an object of the present disclosure is to provide an optical member that can ensure a wider field of view in blind spots without increasing the size of the light guide. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, the optical element comprises a light guide (2) made of a light-transmitting material having a curved incident surface (2a) onto which external light (L1) is incident, a plurality of protruding prism portions (3) and a plurality of flat portions (4) that are flat surfaces, an exit portion (2b) adjacent to the incident surface, a first inclined surface (2c) and a second inclined surface (2d) facing the exit portion, and a connecting surface (2e) connecting the incident surface and the first inclined surface, wherein the incident surface is a curved surface that is recessed more at the center than at the ends, a virtual plane parallel to one plane formed by the plurality of flat portions is defined as a parallel plane (VP), and the angle formed by each surface of the light guide with the parallel plane is defined as an inclination angle, the inclination angle of the first inclined surface is the same as or different from the inclination angle of the second inclined surface, and the first inclined surface is adjacent to the second inclined surface, and the first inclined surface and the second inclined surface are not parallel to the flat portions.

[0008] This optical element is configured so that a wide range of external light in the blind spot area is incident on the concavely curved entrance surface, and the incident light entering the light guide is guided by total reflection at the flat portion, the first inclined surface, and the second inclined surface, and then exits to the outside through the prism portion. Therefore, this optical element can ensure a wider field of view in the blind spot area provided by the attached light shield without increasing the size of the light guide. Furthermore, because the first inclined surface and the second inclined surface are not parallel to the flat portion and have the same or different inclination angles, external light incident on the entrance surface at different angles is separated by the first inclined surface and the second inclined surface and exits from different regions of the exit portion. Therefore, this optical element allows the viewer to see the external view in a wider range of the blind spot area while ensuring visibility.

[0009] According to another aspect of the present disclosure, there is provided an optical element comprising a light guide (2) made of a light-transmitting material, the light guide (2) having a curved incident surface (2a) onto which external scene light (L1) is incident, an exit portion (2b) adjacent to the incident surface, a smooth surface (2h) facing the exit portion, and a connecting surface (2e) connecting the incident surface and the smooth surface, the incident surface being a curved surface that is recessed more at the center than at the ends, and the exit portion having a first region (2ba) in which a plurality of protruding prism portions (3) and a plurality of first inclined portions (7) are alternately and repeatedly arranged, and a connecting surface (2e) adjacent to the first region and including a plurality of prism portions and a plurality of second inclined portions (8). ) are alternately and repeatedly arranged, and the plurality of prism portions are arranged parallel to each other with the same extension direction, and are perpendicular to the extension direction of the plurality of prism portions, the direction from the incident surface side to the opposite side of the incident surface is the light guiding direction (D2), the smooth surface is parallel to the light guiding direction, and the angle between each surface of the light guide and a parallel plane (VP) parallel to the smooth surface is the inclination angle, the inclination angle of the first inclined portion is different from the inclination angle of the second inclined portion, and the first inclined portion and the second inclined portion are not parallel to the smooth surface.

[0010] This optical element is configured so that a wide range of external light in the blind spot area is incident on the concavely curved entrance surface, and the incident light entering the light guide is guided by total reflection at the first inclined portion, the second inclined portion, and the smooth surface, and then exits to the outside through the prism portion. Therefore, this optical element can ensure a wider field of view in the blind spot area provided by the attached light shield without increasing the size of the light guide. Furthermore, because the first inclined portion and the second inclined portion are not parallel to the smooth surface but have different inclination angles, external light incident on the entrance surface at different angles is separated by the first inclined portion and the second inclined portion and exits from different regions of the exit portion. Therefore, this optical element allows the viewer to see the external scene in a wider range of the blind spot area while ensuring visibility.

[0011] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing an optical member according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] 3A and 3B are explanatory diagrams of light guide in the optical member of the first embodiment. [Figure 4] FIG. 4 is an explanatory diagram of the inclination angle of a first inclined surface. [Figure 5] FIG. 10 is an explanatory diagram of the inclination angle of the second inclined surface. [Figure 6] FIG. 3 is a cross-sectional view showing an optical member of a comparative example, which corresponds to FIG. 2. [Figure 7] FIG. 10 is a diagram showing an example of a blind spot area obtained by an optical member of a comparative example. [Figure 8] 4A and 4B are diagrams illustrating an example of a blind spot area obtained by the optical member according to the first embodiment. [Figure 9] 10 is an explanatory diagram of the incident height and focal length when the incident surface is considered to be a concave lens. FIG. [Figure 10]FIG. 4 is a cross-sectional view showing a modified example of the optical member of the first embodiment. [Figure 11] FIG. 10 is a cross-sectional view showing an optical member according to a second embodiment, which corresponds to FIG. 2. [Figure 12] 10 is an explanatory diagram of light guide in an optical member according to a second embodiment, and corresponds to FIG. 3. FIG. [Figure 13] FIG. 4 is an explanatory diagram of the inclination angle of a first inclined portion. [Figure 14] FIG. 10 is an explanatory diagram of the inclination angle of a second inclined portion. [Figure 15] FIG. 10 is a cross-sectional view showing a modified example of the optical member of the second embodiment. [Figure 16] FIG. 10 is a cross-sectional view showing an optical member according to a third embodiment, which corresponds to FIG. 2. [Figure 17] 10 is a cross-sectional view showing a modified example of the optical member according to the embodiment, and corresponds to FIG. 2. FIG. [Figure 18] 10 is a cross-sectional view showing another modified example of the optical member according to the embodiment, which corresponds to FIG. 2. FIG. [Figure 19] 10 is a cross-sectional view showing another modified example of the optical member according to the embodiment, which corresponds to FIG. 2. FIG. [Figure 20] 20 is an explanatory diagram of light guide in the optical member of FIG. 19. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following embodiments, identical or equivalent parts will be denoted by the same reference numerals.

[0014] (First embodiment) An optical member 1 according to a first embodiment will be described with reference to the drawings.

[0015] In Fig. 1, to make it easier to understand the configuration of the light guide 2 (described later), a portion of the outer periphery of the light guide 2 that cannot be seen directly from the angle shown in Fig. 1 is shown with a dashed line. In Fig. 3, to make it easier to distinguish and see light from the blind spot area that is incident on the incident surface 2a (described later) at different angles, light for each predetermined angle range is shown with a solid line, a dashed line, and a dashed-dotted line, respectively. In Figs. 7 and 8, to make it easier to understand the area that the viewer can see through the optical member, the light that is incident on the incident surface and the light that is emitted from the emission portion toward the viewer's viewpoint are hatched, although they do not show cross sections.

[0016] [Basic configuration] The optical member 1 of the present embodiment is attached to, for example, a member or obstacle that blocks the user's field of view and creates a blind spot, and is used as a blind spot assistance device that allows the user to visually recognize the scene in the blind spot. In this specification, a case where the optical member 1 is attached to a light blocking body that creates a wide blind spot, such as a wall, will be described as a representative example, but the present invention is not limited to this example and the optical member 1 can also be attached to other obstacles, members, etc.

[0017] 1 and 2, the optical member 1 of this embodiment is composed of a light guide 2 made of a light-transmitting material. The light guide 2 has an incident surface 2a, an exit portion 2b, a first inclined surface 2c, a second inclined surface 2d, a connecting surface 2e, an end surface 2f, and a side surface 2g, and the exit portion 2b is composed of a plurality of protruding prism portions 3 and a plurality of flat portions 4. The optical member 1 guides light that enters the light guide 2 from the incident surface 2a within the light guide 2 by total reflection and emits the light to the outside from the prism portions 3 of the exit portion 2b, allowing a viewer positioned on the side of the exit portion 2b to view an external scene ahead of the incident surface 2a.

[0018] For ease of explanation, the direction normal to the flat portion 4 of the optical member 1 will be referred to as the "thickness direction D1," as shown in FIGS. 1 and 2. The thickness direction D1 can also be interpreted as the direction connecting the flat portion 4 with the first inclined surface 2c, the second inclined surface 2d, and the end surface 2f. The direction perpendicular to the thickness direction D1, extending from the incident surface 2a toward the end surface 2f, i.e., the direction along which light entering the light guide 2 from the incident surface 2a is guided, will be referred to as the "light guiding direction D2." The light guiding direction D2 can also be interpreted as the arrangement direction along which the multiple prism portions 3 and flat portions 4 are repeatedly arranged. The direction from one end of the incident surface 2a facing the exit portion 2b toward the other end on the opposite side will be referred to as the vertical direction, and the horizontal direction perpendicular to the vertical direction, i.e., the direction connecting the two opposing side surfaces 2g, will be referred to as the "width direction D3." The directions D1 to D3 indicated by arrows in each figure correspond to the above-mentioned directions.

[0019] Also, for ease of explanation, as shown in Figures 3 and 4, external light incident on the incident surface 2a is referred to as "external light L1," light entering the inside of the light guide 2 from the incident surface 2a is referred to as "incident light L2," and light emitted from the inside of the light guide 2 to the outside is referred to as "emitted light L3."

[0020] Furthermore, the region in front of the incident surface 2a as viewed from the exit portion 2b side is defined as the front region, and the angle between the traveling direction of the external scene light L1 and the thickness direction D1 is defined as the incident angle. The region of the front region where the incident angle of the external scene light L1 falls within a predetermined range centered on θa is referred to as the "first front region R1." The region of the front region adjacent to the first front region R1 where the incident angle of the external scene light L1 falls within a predetermined range centered on θb, which is different from θa, is referred to as the "second front region R2." The region of the front region adjacent to the second front region R2 where the incident angle of the external scene light L1 falls within a predetermined range centered on θc, which is different from θa and θb, is referred to as the "third front region R3." For example, if the maximum incident angle of light from the third front region R3 is 60°, θa, θb, and θc are approximately 10°, 30°, and 50°, respectively.

[0021] Of the external scene light L1, light from the first forward region R1, the second forward region R2, and the third forward region R3 will be referred to as "first external scene light L11," "second external scene light L12," and "third external scene light L13," respectively. Furthermore, of the incident light L2, the first external scene light L11, the second external scene light L12, and the third external scene light L13 that are incident will be referred to as "first incident light L21," "second incident light L22," and "third incident light L23," respectively. Of the emitted light L3, the first incident light L21, the second incident light L22, and the third incident light L23 that are emitted to the outside will be referred to as "first emitted light L31," "second emitted light L32," and "third emitted light L33," respectively.

[0022] The light guide 2 is a substantially plate-shaped single member made of a light-transmitting material such as a resin material, e.g., polyethylene terephthalate, polycarbonate, polyethylene, or acrylic, or glass. The light guide 2 is formed, for example, by a known resin molding method using a mold (not shown). As shown in FIG. 3, the light guide 2 is configured such that a portion of incident light L2 from the incident surface 2a enters the prism portion 3 of the exit portion 2b, and the remaining portion of the incident light L2 is reflected by the flat portion 4, and this reflected light is directed toward the first inclined surface 2c or the second inclined surface 2d. The light guide 2 is designed so that the incident light L2 reflected by the flat portion 4 is totally reflected by the first inclined surface 2c, the second inclined surface 2d, and the flat portion 4, and is guided internally. Specifically, the refractive index of the material constituting the light guide 2 is defined as n, and the incident angle of the incident light L2 with respect to the flat portion 4, the first inclined surface 2c, or the second inclined surface 2d, i.e., the light guide angle, is defined as φ. The light guide angle φ here refers to the angle between the normal to the plane on which the incident light L2 is incident and the traveling direction of the incident light L2. In this case, the optical member 1 is designed to satisfy the following formula (1) when the external medium of the light guide 2 is an air layer with a refractive index of 1.

[0023] sinφ>1 / n (1) As a result, even though the light guide 2 does not have a reflective layer made of a reflective material such as a half mirror or a mirror, part of the incident light L2 is repeatedly reflected between the flat portion 4 and the inclined surfaces 2c and 2d, and the incident light L2 is emitted to the outside from an emission surface 3a (described later) of the prism portion 3. Note that the flat portion 4 and the inclined surfaces 2c and 2d are not parallel to each other and the inclination angles (described later) of the inclined surfaces 2c and 2d are different, so that the flat portion 4, the first inclined surface 2c, and the second inclined surface 2d have different light guide angles φ.

[0024] The incident surface 2a is a surface that allows external scene light L1 to enter the interior, as shown in Fig. 3, for example. The incident surface 2a is adjacent to the exit portion 2b and extends in a direction intersecting the exit portion 2b and the first inclined surface 2c. For example, the end of the incident surface 2a opposite to the exit portion 2b side protrudes beyond the first inclined surface 2c, the second inclined surface 2d, and the terminal surface 2f.

[0025] As shown in FIG. 1, the entrance surface 2a has different radii of curvature in the vertical and horizontal directions, and is a concave curved surface with the center in the vertical direction recessed more than the ends. Specifically, the entrance surface 2a has a curved shape with a predetermined radius of curvature in the vertical direction from the end on the exit section 2b side to the opposite end, and a toroidal curved surface with a linear planar shape in the width direction D3 perpendicular to the vertical direction. The toroidal curved surface may also be referred to as a toroidal surface. As a result, the entrance surface 2a has a shape that allows the magnification in the vertical direction and the magnification in the horizontal direction to be independently adjusted, thereby ensuring the range of the blind spot visible to the viewer located on the exit section 2b side.

[0026] The exit portion 2b is formed adjacent to and intersecting the incident surface 2a and includes, for example, multiple prism portions 3, which are triangular protrusions, and multiple flat portions 4 in a cross-sectional view. As shown in FIG. 2, the exit portion 2b is configured by repeatedly arranging the prism portions 3 and flat portions 4 from the incident surface 2a toward the terminal surface 2f. The exit portion 2b includes, for example, a first region 2ba, a second region 2bb, and a third region 2bc, in which the width ratio of the prism portions 3 to the flat portions 4 in the light guide direction D2 differs. The first region 2ba and the second region 2bb are configured by alternately arranging the prism portions 3 and the flat portions 4, and reflect and emit the incident light L2. The first region 2ba has a larger width ratio of the flat portions 4 than the second region 2bb, and reflects a larger proportion of the incident light L2 than the second region 2bb. The third region 2bc is configured only by multiple prism portions 3 and mainly emits the incident light L2 to the outside. That is, the output unit 2b is configured such that the width ratio of the flat portion 4 increases in the region of the regions 2ba to 2bc closer to the incident surface 2a, i.e., the reflectance of the incident light L2 inside the region is higher. That is, the output unit 2b is configured such that the ratio of the output of the incident light L2 in the regions 2ba to 2bc is approximately uniform, thereby making the amount of output light L3 approximately uniform and suppressing uneven brightness in the light guide direction D2.

[0027] The multiple prism portions 3 are protrusions that protrude from the flat portion 4, and extend, for example, along the width direction D3, are arranged parallel to one another, and have approximately the same height in the thickness direction D1. In this specification, "approximately the same" includes not only completely identical cases, but also cases where there are slight differences due to unavoidable factors such as processing errors, but are almost identical. For example, in a cross-sectional view, the multiple prism portions 3 each have an exit surface 3a located on the terminal surface 2f side, which emits a portion of the incident light L2 to the outside, and an adjacent surface 3b located on the incident surface 2a side, which is adjacent to the exit surface 3a.

[0028] The flat portions 4 are, for example, flat surfaces that face the first inclined surface 2c or the second inclined surface 2d, extend along the width direction D3, and are arranged parallel to one another. The flat portions 4 are, for example, arranged on the same plane, constituting a single plane. Because the incident light L2 from the incident surface 2a is incident at an angle equal to or greater than the critical angle, the flat portions 4 function as reflective surfaces that reflect the incident light L2 toward the first inclined surface 2c or the second inclined surface 2d by total reflection.

[0029] The first inclined surface 2c is, for example, a single flat inclined surface facing a portion of the flat portions 4 and inclined so as not to be parallel to the flat portions 4. A virtual plane parallel to one plane formed by the flat portions 4 is defined as a parallel plane VP, and the angle between each surface of the light guide 2 and the parallel plane VP is defined as an inclination angle. The first inclined surface 2c has an inclination angle α. The first inclined surface 2c is adjacent to the second inclined surface 2d and is formed closer to the incident surface 2a than the second inclined surface 2d. The first inclined surface 2c functions as a second reflecting surface that reflects a portion of the incident light L2 reflected by the flat portions 4 toward the exit portion 2b by total reflection, with the flat portions 4 serving as a first reflecting surface. Furthermore, since the incident surface 2a is a concave curved surface, the first inclined surface 2c also functions as a first adjusting surface that adjusts the reflection angle of the incident light L2, which has a larger incident angle than when the incident surface 2a is a flat surface.

[0030] Similar to the first inclined surface 2c, the second inclined surface 2d is a single flat inclined surface that faces some of the flat portions 4 and is inclined so as not to be parallel to the flat portions 4. The second inclined surface 2d has an inclination angle β different from α, for example, which is larger than that of the first inclined surface 2c. The second inclined surface 2d functions as a third reflecting surface that reflects a portion of the incident light L2 reflected by the flat portions 4 toward the exit portion 2b by total reflection. Similar to the first inclined surface 2c, the second inclined surface 2d also functions as a second adjusting surface that adjusts the reflection angle of the incident light L2, which has a larger incident angle than when the incident surface 2a is a flat surface, because the incident surface 2a is a concave curved surface.

[0031] The inclination angle α of the first inclined surface 2c and the inclination angle β of the second inclined surface 2d are designed to have predetermined values ​​in order to adjust the reflection angle of the incident light L2. Details of this will be described later.

[0032] The connecting surface 2e is a surface connecting the incident surface 2a and the first inclined surface 2c, and is, for example, a single flat surface inclined so that the closer it is to the first inclined surface 2c, the closer it is to the terminal surface 2f. The connecting surface 2e is a surface that does not contribute to the guiding of the incident light L21 to L23, and its shape and the like can be changed as appropriate. The connecting surface 2e may be formed with a light-shielding film (not shown) to prevent unintended light from entering the light guide 2 and causing ghost images.

[0033] The terminal surface 2f is a surface connecting the second inclined surface 2d and the emission portion 2b, and is, for example, a single flat surface. The surface shape, inclination, etc. of the terminal surface 2f can be changed as appropriate as long as it does not prevent a portion of the incident light L2 reflected by the second inclined surface 2d from entering the emission portion 2b.

[0034] The side surface 2g is, for example, a single flat surface connecting the incident surface 2a, the exit portion 2b, the first inclined surface 2c, the second inclined surface 2d, the connecting surface 2e, and the terminal surface 2f, and is formed on both ends in the width direction D3. Like the connecting surface 2e, the side surface 2g is a surface that does not contribute to guiding the incident light L21 to L23, and the shape etc. of the side surface 2g may be appropriately changed, and a light-shielding film etc. (not shown) may be formed on the side surface 2g.

[0035] The basic configuration of the optical member 1 has been described above.

[0036] [Design of light guide and inclined surface in light guide body] Next, the design of the light guide and the inclination angles of the inclined surfaces 2c and 2d in the light guide body 2 will be described with reference to the drawings.

[0037] In Figures 4 and 5, for ease of explanation, the outline of the incident surface 2a as if it were a flat surface is shown by a dashed line, and the parallel plane VP passing through the boundary between the first inclined surface 2c and the connecting surface 2e is shown by a dotted line.

[0038] The light guide 2 receives external light L11 to L13 at different incident angle ranges from the first front region R1, the second front region R2, and the third front region R3 on the concavely curved incident surface 2a. The incident light L21 to L23 incident on the incident surface 2a has different light guide angles with respect to the imaginary plane formed by the flat portions 4, and is incident on the exit portion 2b side at different incident angles.

[0039] 3, the first incident light L21 is incident on the prism portion 3 and is emitted from the first region 2ba as the first emitted light L31. The second incident light L22 and the third incident light L23 are incident on the flat portion 4 at angles equal to or greater than the critical angle and are reflected by the first inclined surface 2c or the second inclined surface 2d at different reflection angles.

[0040] The first inclined surface 2c is designed to have an inclination angle α to totally reflect the second incident light L22 and the third incident light L23 reflected by the first region 2ba at different angles and separate these light beams. Specifically, as shown in FIG. 4, for example, assuming that the incident surface 2a is a virtual plane VPa indicated by the dashed line, the light guide angle of the virtual incident light LV1 incident from the virtual plane VPa relative to the flat portion 4 is θ1. In this case, when the external scene light L1 is incident from the concavely curved incident surface 2a, the increase in the light guide angle of the incident light L2 relative to the flat portion 4 is A, based on the incident surface 2a being the virtual plane VPa. The first inclined surface 2c is designed so that α = A / 2. As a result, the first inclined surface 2c reflects the second incident light L22 to the second region 2bb and the third incident light L23 reflected by the first region 2ba to the flat portion 4.

[0041] The second inclined surface 2d is designed to have an inclination angle β so that the third incident light L23 is mainly incident thereon and is totally reflected toward the third region 2bc. Specifically, as shown in FIG. 5, a light guide is assumed in which the incident surface 2a is a virtual plane VPa indicated by the dashed line, and a parallel plane VP is provided instead of the first inclined surface 2c and the second inclined surface 2d. In this case, θ2 is the light guide angle of the virtual reflected light LV2 when the light incident from the incident surface of the virtual plane VPa is reflected by the flat portion 4 and the parallel plane VP, and then reflected again by the flat portion 4. Using the light guide angle of the hypothetical light guide described above as a reference, the increase in the light guide angle of the incident light L2 when the external scene light L1 is incident from the concavely curved incident surface 2a, reflected by the flat portion 4 and the first inclined surface 2c, and then reflected again by the flat portion 4 is expressed as B. The light guide angle is then θ2 + B. In this case, the second inclined surface 2d is designed so that β=B / 2 is satisfied, so that the second inclined surface 2d reflects the third incident light L23 to the third region 2bc.

[0042] In this way, the light guide 2 has an incident surface 2a that is a concave curved surface, and the inclined surfaces 2c and 2d are inclined so that α = A / 2 and β = B / 2 are satisfied, respectively, as described above, so that the external scene light L1 from the different forward regions R1 to R3 is separated internally. As a result, the external scene light L11 from the first forward region R1 is emitted from the first region 2ba, the external scene light L12 from the second forward region R2 is emitted from the second region 2bb, and the external scene light L13 from the third forward region R3 is emitted from the third region 2bc, and each reaches the viewpoint of a viewer (not shown) on the emission portion 2b side. In other words, by adjusting the inclination angles of the inclined surfaces 2c and 2d, the light guide 2 emits light from the forward regions R1 to R3 without overlapping at the emission portion 2b, improving visibility in blind spots.

[0043] Furthermore, since the entrance surface 2a of the light guide 2 is a concave curved surface, light from a wider blind spot area enters the interior compared to when the entrance surface is flat, and this light is emitted from the emission section 2b, ensuring a wider field of view.

[0044] Here, the securing of a wide field of view by the optical member 1 will be described in comparison with a comparative optical member 10 having a flat incident surface 10a as shown in Fig. 6. Note that Figs. 7 and 8 show simplified views of the exit portions of the optical member 1 and the comparative optical member 10.

[0045] Optical element 10 of the comparative example includes plane incident surface 10a, exit portion 10b corresponding to exit portion 2b, smooth surface 10c facing exit portion 10b, connecting surface 10d connecting entrance surface 10a and smooth surface 10c, and terminal surface 10e. Exit portion 10b is configured such that prism portions 11 corresponding to prism portion 3 and flat portions 12 that are flat surfaces are alternately arranged in a repeated pattern, with the multiple prism portions 11 arranged in parallel with the same extension direction. Smooth surface 10c is parallel to the multiple flat portions 12.

[0046] As shown in FIG. 7 , the optical element 10 of the comparative example is attached to a wall-shaped light blocking body 100, and emits light incident on the incident surface 10a from the emission portion 10b, allowing the viewer to view a portion of a blind spot area created by the light blocking body 100. For example, assume that a viewer is facing forward in a direction along the wall-shaped light blocking body 100, with the side from which a portion of the optical element 10 of the comparative example protrudes being the front and the opposite side being the rear, and is located behind the optical element 10. In this case, the viewer's field of view in the area in front of the viewer that is closer to the light blocking body 100 than the viewer's front is mainly comprised of two areas: an area R4 that is not hidden by the light blocking body 100, and a predetermined area R5 in front of the light blocking body 10a. The predetermined area R5 is a portion of the blind spot area and is visible due to the light L3 emitted from the optical element 10.

[0047] For ease of explanation, the viewpoint of the viewer is defined as Pe, and the angle formed by the region R4 projected onto the viewpoint Pe of the viewer at the viewpoint Pe is defined as θ3. Furthermore, when the predetermined region R5 is projected directly onto the viewpoint Pe without passing through the optical member 10, the angle formed by the predetermined region R5 at the viewpoint Pe is defined as θ4.

[0048] For example, when the linear distance X between the viewer's viewpoint Pe and the center position of the emission portion 10b of the optical member 10 is 650 mm, the angle θ3 of the region R4 is approximately 30°. Furthermore, when the width W of the emission portion 10b of the optical member 10 is 200 mm and the thickness T of the portion where the emission portion 10b faces the smooth surface 10c is 15 mm, the angle θ4 of the predetermined region R5 is approximately 10°. In other words, in this case, by using the optical member 10 of the comparative example, the viewer can ensure a field of view that includes the predetermined region R5 with a blind spot of approximately 10° in addition to the approximately 30° of the region R4.

[0049] Here, if it is desired to ensure a wider predetermined region R5, i.e., to increase θ4, it is necessary to increase the area of ​​the incident surface 10a of the optical element 10 of the comparative example. For example, if θ4 is increased from approximately 10° to 30°, the thickness T exceeds 45 mm, and the optical path length for reflection at the exit portion 10b and the smooth surface 10c becomes long. Therefore, the width W must also be increased to approximately 600 mm, which results in a very large optical element 10 of the comparative example. Such an increase in size makes processing difficult due to the increased weight and size of the optical element 10, increases manufacturing costs, and also increases the amount of optical element 10 that protrudes from the light blocking body 100.

[0050] In contrast, as shown in Fig. 8, the optical member 1 of this embodiment has a concavely curved entrance surface 2a, which allows external scene light L1 from a wider area of ​​the blind spot to be captured by the entrance surface 2a. For example, when a predetermined area R5 is projected onto the entrance surface 2a, the angle θ5 formed by the predetermined area R5 at the entrance surface 2a is set to be greater than 10°. For example, by appropriately designing the radius of curvature of the concavely curved surface according to the angular range of external scene light L1 in the blind spot that is desired to be captured by the entrance surface 2a, it is possible to set θ5 to approximately 30°. Note that the angles θ3 to θ5 correspond to the visual angle.

[0051] Here, when the incident surface is flat like the optical element 10 of the comparative example, the area that can be viewed by the viewer at the exit portion without reducing the view in the blind spot is approximately θ4 = 10°, i.e., a viewing angle of approximately 10°. To allow the viewer to view a predetermined area R5 at θ4 = 30° without reducing the view in the blind spot, the optical element must be enlarged. However, the optical element 1 has a toroidal curved incident surface 2a, and by adjusting the radius of curvature, it is possible to allow the viewer to view a reduced view in the blind spot. Therefore, when the width W of the exit portion 2b is 200 mm, the maximum thickness T of the portion where the exit portion 2b and the second inclined surface 2d face each other is 15 mm, and the linear distance between the viewer and the center position of the exit portion 2b is 650 mm, the optical element 1 is capable of allowing the viewer to view a blind spot with a viewing angle of 30°. In other words, because the entrance surface 2a of the optical member 1 is a toroidal curved surface, it is possible to visually recognize a wider blind spot area while maintaining a thickness T and width W that are similar to those of the comparative optical member 10. In the above example, the optical member 1 reduces the scene at a visual angle of 30° in the blind spot area to about one-third the size in the vertical direction of the concave curved surface, but does not reduce it in the width direction D3, and the scene obtained is visually recognized at the exit portion 2b.

[0052] In addition, by forming the incident surface 2a into a toroidal curved surface with different radii of curvature in the vertical and horizontal directions, the vertical reduction magnification x and the horizontal reduction magnification y can be independently adjusted in the optical member 1. For example, when the angle range to be viewed at the exit portion 2b is adjusted by the vertical magnification x and the horizontal magnification y, it can be expressed as a polynomial as ax + b + cx 2 +dy 2 +ex 3 +fy 3 +gx 4 +hy 4 In this way, the x and y terms are independent of each other and there are no mutual terms. Note that a, b, c, d, e, f, g, and h in the above polynomial example are arbitrary coefficients.

[0053] Furthermore, the incident surface 2a is regarded as a concave lens, and external scene light L with incident angles A and B is incident on the incident surface 2a as shown in Figs. 9(a) and 9(b).A , L B When these rays are incident on the incident surface 2a, the incident height is h A , h B and the focal length of the concave lens is f. Note that for ease of viewing, Figures 9(a) and (b) only show a portion of the incident surface 2a of the light guide 2, and omit other portions. The focal length f is expressed as f = r(n-1), where r is the radius of curvature of the concave curved surface of the incident surface 2a and n is the refractive index of the material that makes up the light guide 2. Incident height h A , h B is the distance in the thickness direction D1 between the height center hc of the incident surface 2a in the thickness direction D1 and the incident positions P2 and P3 on the incident surface 2a of light with an incident angle A or B that reaches point P1 at the height center hc and focal length f. In this case, it is preferable that the light guide 2 is designed to satisfy the following expressions (2) and (3):

[0054] tanA=h A / f···(2) tanB=h B / f···(3) As a result, the optical element 1 prevents the external light L1 from the first forward region R1, the second forward region R2, and the third forward region R3 from being emitted in an overlapping state at the emission portion 2b, thereby achieving the effect of further improving visibility in blind spot areas.

[0055] Note that, for the second external scene light L12 having the incident angle θb, the light guide angle of the second incident light L22 with respect to the flat portion 4 is increased by A compared to when the incident surface 2a is flat. Also, for the third external scene light L13 having the incident angle θc, the light guide angle of the third incident light L23 with respect to the flat portion 4 is increased by B compared to when the incident surface 2a is flat and has a surface equivalent to the parallel plane VP instead of the inclined surfaces 2c and 2d.

[0056] According to this embodiment, in the optical member 1, a wide range of external scene light L1 in the blind spot region is incident on the concave incident surface 2a, and the incident light L2 that enters the light guide 2 is guided by total reflection at the flat portion 4, the first inclined surface 2c, and the second inclined surface 2d, and is emitted to the outside from the prism portion 3. Therefore, the optical member 1 can ensure a wider field of view in the blind spot region by the attached light blocking body 100, without increasing the size of the light guide 2.

[0057] Furthermore, because the first inclined surface 2c and the second inclined surface 2d are not parallel to the flat portion 4 and have different inclination angles α and β, external scene light L1 that is incident at different angles on the incident surface 2a is separated by the first inclined surface 2c and the second inclined surface 2d and emitted from different regions of the emission portion 2b. Therefore, this optical member allows the viewer to view the external scene in a wider range of blind spot areas and ensures that visibility is maintained.

[0058] (Modification of the first embodiment) 10, the optical member 1 may have a prism array configuration in which the first inclined surface 2c and the second inclined surface 2d are not a single flat surface but are made up of multiple prism portions having inclined surfaces of the same inclination. Specifically, the first inclined surface 2c is made up of a repeated arrangement of multiple protruding prism portions 5, each having an inclined surface 5a with an inclination angle α and an adjacent surface 5b adjacent thereto. The second inclined surface 2d is made up of a repeated arrangement of multiple protruding prism portions 6, each having an inclined surface 6a with an inclination angle β and an adjacent surface 6b adjacent thereto. For example, the heights of the prism portions 5, 6 in the thickness direction D1 of the first inclined surface 2c and the second inclined surface 2d are approximately the same.

[0059] This embodiment also provides an optical member 1 that can achieve the same effects as the first embodiment. Furthermore, by forming the inclined surfaces 2c and 2d into a prism array with approximately the same height in the thickness direction D1, the thickness of the portion of the light guide 2 where the emission portion 2b faces the inclined surfaces 2c and 2d can be reduced, which also has the effect of reducing the weight of the light guide 2. Furthermore, the vertices of the prism portions 5 and 6 that form the inclined surfaces 2c and 2d are configured to be located on approximately the same plane, which also has the effect of facilitating attachment to the light blocking body 100.

[0060] (Second embodiment) The optical member 1 of the second embodiment will be described with reference to FIGS.

[0061] 11, the optical member 1 of this embodiment differs from the first embodiment in that the configuration of a portion of the emission section 2b is changed and that a single smooth surface 2h is provided instead of the inclined surfaces 2c and 2d. This difference will be mainly described in this embodiment.

[0062] The light guide direction D2 in this embodiment is a direction along the plane of the smooth surface 2h, and corresponds to the direction from the incident surface 2a toward the terminal surface 2f along the arrangement direction of the plurality of prism portions 3. Alternatively, the light guide direction D2 in this embodiment can be said to be a direction along the arrangement direction of the plurality of prism portions 3 arranged in parallel in the exit portion 2b, and perpendicular to the extension direction of the plurality of prism portions 3.

[0063] In this embodiment, the first region 2ba is formed by alternately arranging prism portions 3 and first inclined portions 7, which are flat surfaces with an inclination angle α. In this embodiment, the second region 2bb is formed by alternately arranging prism portions 3 and second inclined portions 8, which are flat surfaces with an inclination angle β. In this embodiment, the portion of the light guide 2 that connects the connection surface 2e and the terminal surface 2f is a single flat surface, called a smooth surface 2h. That is, in the light guide 2, the first inclined portions 7 correspond to the first inclined surface 2c, the second inclined portions 8 correspond to the second inclined surface 2d, and the smooth surface 2h corresponds to the flat portion 4.

[0064] The first inclined portion 7 and the second inclined portion 8 have inclination angles α and β, respectively, and serve to adjust the reflection angles of incident light beams L21 to L23 having different light guide angles. Since the light reflected by the first inclined portion 7 or the second inclined portion 8 is incident at an angle equal to or greater than the critical angle, the smooth surface 2h reflects the light beam back toward the exit portion 2b by total reflection. As a result, the light guide 2 is configured such that the first incident light beam L21 mainly exits from the first region 2ba, the second incident light beam L22 mainly exits from the second region 2bb, and the third incident light beam L23 exits from the third region 2bc, as shown in FIG. 12, for example.

[0065] 13, assuming that incident surface 2a is a virtual plane VPa indicated by a dashed line, the light-guiding angle of virtual incident light LV3 incident from virtual plane VPa with respect to parallel plane VP is θ6. In this case, when external scene light L1 is incident from incident surface 2a, which has a concave curve, and the increase in the light-guiding angle of incident light L2 with respect to parallel plane VP is A, based on the case when incident surface 2a is virtual plane VPa, the light-guiding angle is θ6 + A. In this case, first inclined portion 7 is designed so that α = A / 2.

[0066] 14, assume a light guide having an incident surface 2a that is a virtual plane VPa indicated by a dashed line, and a parallel plane VP that passes through the boundary between the inclined portion 7 and the prism portion 3, instead of the first inclined portion 7 and the second inclined portion 8. In this case, the light guide angle of the virtual reflected light LV4 is θ7 when the light incident from the incident surface of the virtual plane VPa is reflected from the parallel plane VP and the smooth surface 2h, and then incident on the parallel plane VP of the second region 2bb. Using the light guide angle of the above-described hypothetical light guide as a reference, when external scene light L1 enters the concavely curved incident surface 2a, reflects from the first inclined portion 7 and the smooth surface 2h, and then incidents on the parallel plane VP in the second region 2bb, the increase in the light guide angle of the incident light L2 is B. The light guide angle is θ7 + B. In this case, the second inclined portion 8 is designed so that β = B / 2.

[0067] As a result, in the optical member 1, similarly to the first embodiment, external scene light L11 to L13 having different incident angles are separated by the inclined portions 7 and 8. Then, light corresponding to the external scene light L11 is emitted from the first region 2ba, the external scene light L12 is emitted from the second region 2bb, and the external scene light L13 is emitted from the third region 2bc, thereby improving visibility in blind spot areas.

[0068] This embodiment also provides an optical member 1 that can achieve the same effects as the first embodiment. Furthermore, the light guide 2 has a smooth surface 2h along the light guide direction D2 instead of the inclined surfaces 2c and 2d, and the emission section 2b has inclined sections 7 and 8 instead of the flat section 4, thereby reducing the thickness T and achieving a weight reduction effect, as in the modified example of the first embodiment. Furthermore, the optical member 1 has a smooth surface 2h, which makes it easier to attach to the light blocking body 100.

[0069] (Modification of the second embodiment) As shown in FIG. 15, for example, the optical element 1 may have, instead of a smooth surface 2h, a third inclined surface 2i composed of inclined surfaces 2ia and 2ib inclined at different predetermined angles relative to a parallel plane VP along the light guiding direction D2.

[0070] This modification also provides the optical member 1 that can achieve the same effects as the first embodiment.

[0071] (Third embodiment) An optical member 1 according to the third embodiment will be described with reference to Fig. 16. In Fig. 16, similar to Fig. 3, the outline of the light blocking body 100 is shown by a broken line for ease of viewing.

[0072] The optical member 1 of this embodiment differs from the first embodiment in that the shape of the end of the incident surface 2a opposite to the exit portion 2b is changed, as shown in Fig. 16. This difference will be mainly described in this embodiment.

[0073] In this embodiment, the incident surface 2a has a curved shape in which the end opposite the emission portion 2b is curved, forming a curved portion 9 that is rounded and has a predetermined or greater radius of curvature and no corners. The curved portion 9 is provided to prevent a person from being injured even if the person collides with a portion of the optical member 1 that protrudes from the light blocking body 100. The curved portion 9 may have any curved surface shape that does not have a sharp shape such as a corner that could injure a person, and the radius of curvature can be changed as appropriate.

[0074] For the same reason as above, the end of the incident surface 2a on the side of the exit portion 2b may also be formed into a rounded curved shape similar to that of the curved portion 9.

[0075] This embodiment also provides the optical member 1 that can achieve the same effects as those of the first embodiment. Furthermore, since the end of the incident surface 2a of this optical member 1 is formed as the curved portion 9, even if a person passing near the light blocking body 100 accidentally comes into contact with the optical member 1, the person can be prevented from being injured, and an effect of further improving safety can be achieved.

[0076] (Other embodiments) (1) Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one, or less than one, are also within the scope and spirit of the present disclosure.

[0077] For example, the optical member 1 of the first and second embodiments described above may have a curved portion 9 at the end of the incident surface 2a. Furthermore, the optical member 1 of the second embodiment may have a prism array structure in which prism portions having the same inclination angle α of the first inclined surface 2c and the same inclination angle β of the second inclined surface 2d are repeated, as in the modified example of the first embodiment. Although the optical members 1 of the first embodiment and its modified examples have been described with the inclination angle α of the first inclined surface 2c and the inclination angle β of the second inclined surface 2d being different, this is not limiting and the inclination angles may be the same. In other words, the optical member 1 of the first embodiment may have a single inclined surface 2j with an inclination angle γ, instead of the first inclined surface 2c and the second inclined surface 2d with different inclination angles, as shown in FIG. 17 . Note that the inclination angle γ, like the inclination angles α and β, is appropriately designed depending on the angle change of the incident light L2 when the incident surface 2a is assumed to be a flat surface and when it is a toroidal curved surface. In this way, the optical element 1 can be configured by freely combining some or all of the components of each of the above-mentioned embodiments and their variations within the possible range, and may also be configured by combining some or all of the configurations of the variations described below.

[0078] 18, the optical member 1 may be configured such that the connecting surface 2e is shaped to conform to the portion of the light blocking body 100 to which it is attached, and the gap between the connecting surface 2e and the light blocking body 100 is equal to or smaller than a predetermined value. As a result, when the optical member 1 is attached to the light blocking body 100, there is almost no gap between the end of the incident surface 2a opposite to the emission portion 2b and the light blocking body 100, and the same effect as in the third embodiment can be obtained.

[0079] (3) In the optical member 1, the first inclined surface 2c and the second inclined surface 2d may be curved surfaces concave toward the exit portion 2b and may be toroidal surfaces similar to the entrance surface 2a, as shown in Fig. 19. In this case, the first inclined surface 2c and the second inclined surface 2d may be toroidal surfaces whose radii of curvature change in the light guide direction D2 and whose radii of curvature are linear in the width direction D3, and each may have a different radii of curvature in the light guide direction D2. In this optical member 1, as shown in Fig. 20, the second incident light L22 reflected by the first inclined surface 2c is emitted from the second region 2bb, and the third incident light L23 reflected by the second inclined surface 2d is emitted from the third region 2bc. In this optical member 1, the first inclined surface 2c and the second inclined surface 2d are toroidal curved surfaces whose radii of curvature change in the light-guiding direction D2, so that the second incident light L22 and the third incident light L23 are reflected over different ranges by the output portion 2b. In this optical member 1, the first incident light L21 from the first front region R1 is output as the first output light L31 without passing through the inclined surfaces 2c and 2d, and the second incident light L22 from the second front region R2 is reflected over a wide range by the first inclined surface 2c and output as the second output light L32. In addition, in this optical member 1, the third incident light L23 from the third front region R3 is reflected over a wide range by the second inclined surface 2d, but in a range different from the first inclined surface 2c, and output as the third output light L33.

[0080] As a result, the optical member 1 is configured to emit external light L11-L13 from the first front region R1, the second front region R2, and the third front region R3 from the emission portion 2b at different magnification rates. In other words, in the optical member 1, the inclined surfaces 2c and 2d are toroidal curved surfaces, so that the display sizes of the second region 2bb and the third region 2bc are adjusted independently, improving the difference in display size among the regions 2ba-2bc in the emission portion 2b and providing an effect of improving visibility.

[0081] (4) It goes without saying that in each of the above embodiments, the elements constituting the embodiments are not necessarily essential unless they are specifically stated as essential or are clearly considered essential in principle. Furthermore, in each of the above embodiments, when the numbers, values, amounts, ranges, etc. of the components of the embodiments are mentioned, they are not limited to the specific numbers unless they are specifically stated as essential or are clearly limited to a specific number in principle. Furthermore, in each of the above embodiments, when the shapes, positional relationships, etc. of the components are mentioned, they are not limited to the shapes, positional relationships, etc. unless they are specifically stated or are clearly limited to a specific shape, positional relationship, etc. in principle. [Explanation of symbols]

[0082] 2...Light guide, 2a...Incidence surface, 2b...Emission part, 2ba...First area, 2bb...Second area 2c...first inclined surface, 2d...second inclined surface, 2e...connecting surface, 2h...smooth surface, 3...prism part 4...flat portion, 7...first inclined portion, 8...second inclined portion, D1...thickness direction, D2...light guide direction VP...parallel plane, VPa...virtual plane, VL1, VL3...virtual incident light VL2, VL4...Virtual reflected light

Claims

1. An optical member, The light guide (2) is made of a light-transmitting material and has a curved entrance surface (2a) on which external light (L1) is incident, a plurality of protruding prism portions (3) and a plurality of flat portions (4) which are flat surfaces, an exit portion (2b) adjacent to the entrance surface, a first inclined surface (2c) and a second inclined surface (2d) facing the exit portion, and a connecting surface (2e) connecting the entrance surface and the first inclined surface; The entrance surface is a curved surface having a center recessed inward relative to the ends, a virtual plane parallel to one plane formed by the plurality of flat portions is defined as a parallel plane (VP), and an angle between each surface of the light guide and the parallel plane is defined as an inclination angle, the inclination angle of the first inclined surface is the same as or different from the inclination angle of the second inclined surface, and the first inclined surface is adjacent to the second inclined surface, The optical member, wherein the first inclined surface and the second inclined surface are not parallel to the flat portion.

2. The optical member according to claim 1 , wherein the first inclined surface and the second inclined surface are flat surfaces, and the inclination angles are different from each other.

3. A direction along the parallel plane from the incident surface toward the first inclined surface and the second inclined surface is defined as a light guide direction (D2), and a direction along the first inclined surface and the second inclined surface that is perpendicular to the light guide direction is defined as a width direction, The optical element according to claim 1 , wherein the first inclined surface and the second inclined surface have different radii of curvature in the light guiding direction and in the width direction, are toroidal curved surfaces concave toward the exit portion, and have different radii of curvature in the light guiding direction.

4. It is assumed that there is a flat imaginary plane (VPa) at the position of the incident surface, and the light guide angle of the imaginary incident light (LV1) incident on the light guide body from the imaginary plane with respect to the flat portion is θ1, The light guide angle of the light incident from the incident surface and passing through a position of the flat portion where the virtual incident light reaches is defined as θ1+A, and the inclination angle of the first inclined surface is defined as α. The first inclined surface satisfies α=A / 2, When it is assumed that the virtual incident light is reflected in the order of the flat portion and the parallel surface passing through the boundary between the connection surface and the first inclined surface, and is again incident on the flat portion as virtual reflected light (LV2), a light guide angle of the virtual reflected light with respect to the flat portion is θ2, The light guide angle of the reflected light, which is incident on the incident surface, is reflected in this order by the flat portion and the first inclined surface, and is then incident on the flat portion again, is defined as θ2+B, and the inclination angle of the second inclined surface is defined as β. The optical member according to claim 2 , wherein the second inclined surface satisfies β=B / 2.

5. Considering the incident surface as a concave lens, the radius of curvature of the incident surface is r, the focal length is f, and the refractive index of the light guide is n, the incidence surface satisfies f=r / (n−1); The direction along the normal direction to the flat portion is defined as a thickness direction (D1), the position of the height center of the incident surface in the thickness direction is defined as hc, and a point at the height center position away from the incident surface by the focal length is defined as P1. The incident height of the light passing through P1 and having an incident angle of A along the thickness direction from the height center on the incident surface is defined as h Ａ The incident height of the light B passing through P1 and having an incident angle of B along the thickness direction from the height center on the incident surface is defined as h Ｂ As, The incidence surface is tan A = h Ａ / f, and tan B = h Ｂ / f is satisfied.

6. An optical member, The light guide (2) is made of a light-transmitting material and has a curved incident surface (2a) on which external scene light (L1) is incident, an exit portion (2b) adjacent to the incident surface, a smooth surface (2h) facing the exit portion, and a connecting surface (2e) connecting the incident surface and the smooth surface, The entrance surface is a curved surface having a center recessed inward relative to the ends, The emission section has a first region (2ba) in which a plurality of protruding prism portions (3) and a plurality of first inclined portions (7) are alternately and repeatedly arranged, and a second region (2bb) adjacent to the first region and in which a plurality of the prism portions and a plurality of second inclined portions (8) are alternately and repeatedly arranged, The plurality of prism portions are arranged in parallel with each other with the same extension direction, a light guiding direction (D2) perpendicular to the extension direction of the plurality of prism portions and from the side of the incident surface toward the opposite side to the incident surface, the smooth surface being parallel to the light guiding direction; The angle between each surface of the light guide and a parallel plane (VP) that is parallel to the smooth surface is defined as an inclination angle, and the inclination angle of the first inclined portion is different from the inclination angle of the second inclined portion, The optical member, wherein the first inclined portion and the second inclined portion are not parallel to the smooth surface.

7. It is assumed that a flat imaginary plane (VPa) is present at the position of the incident surface, and the light guide angle of the imaginary incident light (LV3) incident on the light guide body from the imaginary plane with respect to the parallel plane is θ6. The light guide angle of the light incident from the incident surface and passing through a position on the parallel surface where the virtual incident light reaches is defined as θ6+A, and the inclination angle of the first inclined portion is defined as α, The first inclined portion satisfies α=A / 2, When it is assumed that the virtual incident light passes through the boundary between the first inclined portion and the prism portion, is reflected on the parallel surface and the smooth surface in that order, and is again incident on the parallel surface as virtual reflected light (LV4), a light guide angle of the virtual reflected light with respect to the parallel surface is θ7, The incident light is incident on the incident surface, is reflected by the first inclined portion and the smooth surface in this order, and is incident on the second inclined portion. The light guide angle of the reflected light with respect to the parallel surface is θ7+B, and the inclination angle of the second inclined portion is β. The optical member according to claim 6 , wherein the second inclined portion satisfies β=B / 2.

8. Considering the incident surface as a concave lens, the radius of curvature of the incident surface is r, the focal length is f, and the refractive index of the light guide is n, the incidence surface satisfies f=r / (n−1); The direction along the normal direction to the smooth surface is defined as a thickness direction (D1), the position of the height center of the incident surface in the thickness direction is defined as hc, a point at the height center position away from the incident surface by the focal length is defined as P1, and the incident height of the light A at an incident angle passing through P1 along the thickness direction from the height center on the incident surface is defined as h Ａ The incident height of the light B passing through P1 from the height center on the incident surface along the thickness direction is defined as h Ｂ As, The incidence surface is tan A = h Ａ / f, and tan B = h Ｂ / f is satisfied.

9. 9. The optical element according to claim 1, wherein a direction from one end of the incident surface on the side of the exit portion to the other end on the opposite side is defined as a vertical direction, and a direction perpendicular to the vertical direction is defined as a horizontal direction, and the incident surface is a toroidal surface having a radius of curvature in the vertical direction and a radius of curvature in the horizontal direction that are different.

Images