Optical Components

Abstract

To provide an optical member which reduces absorption loss of light in optical guiding, and suppresses brightness of outside view and color tone which a user recognizes through a first face from being changed.SOLUTION: An optical member comprises: an entrance surface 2a where outside light injects; a plurality of flat parts 3; a plurality of prism parts 4; a first face 2b where incident light from the entrance surface 2a firstly reaches; and a transparent material 2 with a second face 2c which is disposed opposite to the plurality of flat parts 3. The plurality of flat parts 3 work as a first reflection surface which totally reflects the incident light to the second face 2c, and the second face 2c works as a second reflection surface which totally reflects the reflectance from the flat parts 3 to the first face 2b. The plurality of prism parts 4 include injection surfaces 4a which inject the incident light to outside.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention 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 example of this type of optical member is described in Patent Document 1. The optical member described in Patent Document 1 has a light guide having an incident surface on which external light enters, a first surface to which the external light entering from the incident surface is initially directed, and a second surface opposite to the first surface, and a semi-transmitting mirror arranged on the first surface side. In this optical member, a part of the external light entering from the incident surface is reflected by the semi-transmitting mirror to the second surface, and the remaining part is absorbed or transmitted by the semi-transmitting mirror, and the second surface reflects the light reflected by the semi-transmitting mirror to the second surface side. In addition, this optical member has a prism sheet having a plurality of prisms arranged on the first surface, and the light transmitted through the semi-transmitting mirror is emitted to the outside via the plurality of prisms.

[0003] As a result, the outside light incident from the incident surface is emitted over a wide range through the multiple prisms on the first surface different from the incident surface, and the user on the first surface side can see a scene located behind the incident surface. This optical member is used, for example, as a blind spot auxiliary device that is placed on a predetermined obstacle and allows the user to see a scene in a blind spot area that is blocked by the obstacle and cannot be directly seen by the user. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6372305 Summary of the Invention [Problem to be solved by the invention]

[0005] Of the above optical members, the semi-transparent mirror is made of, for example, a single-layer metal deposition film obtained by depositing a metal material, or a dielectric multi-layer coating film obtained by coating multiple layers of a dielectric material.

[0006] However, if the semi-transparent mirror is constructed from a single layer of metal vapor deposition film, the light absorption rate of the metal vapor deposition film is high, and there is a large loss of light due to multiple light reflections on the semi-transparent mirror, so the scene viewed by the user through the optical component appears dark.

[0007] On the other hand, when the semi-transmitting mirror is made of a dielectric multi-layer coating film, the optical loss in the semi-transmitting mirror can be suppressed because the dielectric multi-layer coating film has a smaller optical absorptivity than a single-layer metal vapor deposition film.

[0008] However, a dielectric multilayer coating film requires more manufacturing steps than a metal vapor deposition film, and the reflectance of the semi-transparent mirror changes depending on the angle of incidence and wavelength of light on the semi-transparent mirror. Therefore, in this case, the brightness and color of the outside view perceived by the user changes depending on the angle at which the user views the first surface, and the manufacturing cost of the optical component increases.

[0009] In view of the above, an object of the present invention is to provide an optical element that reduces light loss at the first surface of a light guide having an entrance surface, a first surface, and a second surface, while suppressing changes in brightness and color tone of the external scene viewed by a user through the first surface. [Means for solving the problem]

[0010] In order to achieve the above object, the optical member according to claim 1 comprises: It is attached to a component that creates a blind spot and includes light from the blind spot.The optical member guides external scene light by internally reflecting it, and includes a light guide (2) having an entrance surface (2a, 7a) on which the external scene light is incident, a plurality of flat portions (3) and a plurality of prism portions (4), a first surface (2b) on which the incident light entering from the entrance surface first arrives, and a second surface (2c) arranged opposite the plurality of flat portions, the plurality of flat portions being first reflecting surfaces that reflect the incident light toward the second surface by total reflection, the second surface being a second reflecting surface that reflects the reflected light reflected by the flat portions toward the first surface by total reflection, and the plurality of prism portions having an exit surface (4a) that emits a portion of the incident light or a portion of the light reflected by the second surface to the outside. The first surface has a plurality of regions in which the ratio of the width of the prism portion to the width of the flat portion adjacent to each other is different, and the ratio of the width of the prism portion to the width of the flat portion is constant in each of the plurality of regions, and the ratio of the width of the flat portion to the width of the prism portion decreases as the region is located farther from the entrance surface, and the width of the flat portion is zero in a region of a predetermined width located farthest from the entrance surface among the plurality of regions, and the first surface is constituted only by a plurality of prism portions. . The optical member described in claim 4 is an optical member that internally reflects and guides external scene light, and includes a light guide (2) having an entrance surface (2a, 7a) on which external scene light is incident, a plurality of flat portions (3) and a plurality of prism portions (4), a first surface (2b) on which the incident light incident from the entrance surface first arrives, and a second surface (2c) disposed opposite the plurality of flat portions, the plurality of flat portions being a first reflecting surface that reflects the incident light toward the second surface by total reflection, the second surface being a second reflecting surface that reflects the reflected light reflected by the flat portions toward the first surface by total reflection, and the plurality of prism portions being a first reflecting surface that reflects the incident light toward the second surface by total reflection, The prism portion has an exit surface (4a) that emits a portion of the light or a portion of the light reflected by the second surface to the outside, and at least a portion of the prism portions among the plurality of prism portions is trapezoidal in shape having a top surface (4c) adjacent to the exit surface, an end point of the exit surface of the trapezoidal prism portion on the side of the adjacent flat portion is defined as a first end point (V), an end point of the top surface of the adjacent trapezoidal prism portion on the opposite side to the exit surface is defined as a second end point (P), an angle between a virtual line connecting the first end point and the second end point and a line along a normal direction to the plane formed by the flat portion is defined as ε, and an angle between the exit light emitted to the outside from the exit surface and the normal direction is defined as θ. 2 Then, the trapezoidal prism part has a relationship of ε>θ 2 Meet the following.

[0011] This optical member has a light guide having an incident surface, a first surface where the incident light from the incident surface first arrives, and a second surface opposite to the first surface, and the first surface is composed of a plurality of prism portions and a plurality of flat portions. In this optical member, the plurality of flat portions are the first reflecting surface that reflects the incident light to the second surface by total reflection, and the second surface is the second reflecting surface that reflects the light reflected by the flat portions to the first surface. As a result, this optical member can guide the incident light within the light guide without having a semi-transmitting mirror, does not cause light absorption due to the semi-transmitting mirror, and has a structure in which the reflectance of light within the light guide does not depend on the wavelength of the light. Therefore, this optical member has the effect of suppressing changes in the brightness and color tone of the outside scene viewed by the user through the first surface while reducing the loss of light within the light guide.

[0012] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and specific components described in the embodiments described below. [Brief description of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing an optical member according to a first embodiment. [Diagram 2]FIG. 2 is a first explanatory diagram for explaining light guide in the optical member according to the first embodiment. [Diagram 3] FIG. 4 is a second explanatory diagram for explaining light guiding in the optical member according to the first embodiment. [Figure 4] 5 is an explanatory diagram for explaining the relationship between the width of a flat portion and a prism portion on a first surface and the amount of visible light. FIG. [Diagram 5] 5 is a cross-sectional view showing a modified example of the optical member of the first embodiment. FIG. [Figure 6] 11 is an explanatory diagram for explaining noise generation in a prism portion having a structure in which an exit surface and an opposing surface are adjacent to each other; FIG. [Figure 7] 6 is an enlarged cross-sectional view showing the configuration of a prism portion in the optical member of FIG. 5. [Figure 8] FIG. 6 is a cross-sectional view showing an optical member according to a second embodiment. [Figure 9] 13 is an explanatory diagram for explaining light guiding in an optical member according to a second embodiment. FIG. [Figure 10] FIG. 11 is a cross-sectional view showing a modified example of the optical member of the second embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing an optical member according to a third embodiment. [Figure 12] 13 is an explanatory diagram for explaining light guiding in an optical member according to a third embodiment. FIG. [Figure 13] FIG. 4 is an explanatory diagram for explaining light-guiding gaps in the first surface. [Figure 14] 13A and 13B are explanatory diagrams for explaining suppression of gaps in light guide in the optical member according to the third embodiment. [Figure 15] 11 is an explanatory diagram for explaining the relationship between the angle of an inclined surface located between the entrance surface and the second surface and the gap between light rays. FIG. [Figure 16] FIG. 13 is a diagram showing the gap suppression of light rays depending on the angle of the inclined surface located between the entrance surface and the second surface. [Figure 17] 13A to 13C are cross-sectional views showing other examples of the fourth surface of the optical member according to the third embodiment. [Figure 18] FIG. 11 is a cross-sectional view showing a modified example of the optical member of the third embodiment. [Figure 19]19 is an explanatory diagram for explaining the configuration of a first surface in the optical member in FIG. 18. [Figure 20] FIG. 13 is a cross-sectional view showing an optical member according to a fourth embodiment. [Figure 21] 13 is an explanatory diagram for explaining light guiding in an optical member according to a fourth embodiment. FIG. [Figure 22] 11 is an explanatory diagram for explaining the relationship between the angle of the inclined surface of the second prism portion constituting the entrance portion and the gap between light rays. FIG. [Figure 23] 13 is an explanatory diagram for explaining the suppression of gaps between light rays by the angle of the inclined surface of the second prism portion constituting the entrance portion. FIG. [Figure 24] FIG. 13 is a cross-sectional view showing an optical member according to a fifth embodiment. [Diagram 25] 11 is an explanatory diagram for explaining the occurrence of gaps in the light guide due to the width of the incident portion. FIG. [Figure 26] 11 is an explanatory diagram for explaining the occurrence of light loss due to the width of an entrance portion; FIG. [Figure 27] 11 is an explanatory diagram for explaining the suppression of light loss and the suppression of gaps in the light guide due to the width of the incident portion. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals.

[0015] (First embodiment) The optical member 1 of the first embodiment will be described with reference to Fig. 1 to Fig. 4. The optical member 1 of the present embodiment can be used as a blind spot assistance device that is attached to, for example, a member or obstacle that blocks the user's field of vision and creates a blind spot, and allows the user to visually recognize the scene in the blind spot. For example, in the case of an in-vehicle application, the optical member 1 is attached to a pillar of the vehicle in which it is mounted, and guides external light from the blind spot area caused by the pillar to the user's side, allowing the user to visually recognize the scene in the blind spot area.

[0016] In FIG. 4, in order to make it easier to understand the light guide within the optical member 1, the light that enters the optical member 1, and the light that exits from the optical member 1 to the outside are hatched.

[0017] As shown in Fig. 1, the optical member 1 includes a translucent light guide 2 having an incident surface 2a, a first surface 2b different from the incident surface 2a, and a second surface 2c opposite to the first surface 2b, the first surface 2b being composed of a plurality of flat portions 3 and prism portions 4. The light guide 2 constituting the optical member 1 further includes a third surface 2d connecting the first surface 2b and the second surface 2c. As shown in Fig. 2 and Fig. 3, the optical member 1 is configured such that external scene light L1 from the incident surface 2a is guided inside the light guide 2 and is emitted from the first surface 2b different from the incident surface 2a.

[0018] For ease of explanation, the light incident on the light guide 2 from the incident surface 2a is referred to as "incident light L2", and the light of the incident light L2 that is emitted to the outside from the prism portion 4 on the first surface 2b is referred to as "emitted light L3". In addition, the light of the incident light L2 that exits to the outside from the third surface 2d is referred to as "afterglow L4".

[0019] The light guide 2 is made of a translucent material such as a resin material such as polyethylene terephthalate, polycarbonate, polyethylene, or acrylic, or glass. The light guide 2 is designed so that the incident light L2 is totally reflected by the flat portion 3 and the second surface 2c and guided inside. Specifically, the light guide 2 is designed to satisfy the following formula (1), where the refractive index of the constituent material is n1, the refractive index of the external medium of the light guide 2 is n2 (for example, in the case of an air layer, n2=1), and the incident angle of the incident light L2 with respect to the flat portion 3 and the second surface 2c is φ.

[0020] sinφ≧n2 / n1 (1) As a result, the light guide 2 is configured such that, even without a semi-transparent mirror, part of the incident light L2 from the incident surface 2a is totally reflected by the flat portion 3 and the second surface 2c, and is emitted to the outside from the first surface 2b.

[0021] Specifically, as shown in FIG. 2, for example, the external scene light L1 is incident from the incident surface 2a of the optical member 1 at an incident angle θ1, refracts in the light guide 2 to become incident light L2, and first reaches the first surface 2b. A portion of the incident light L2 that reaches the flat portion 3 at a light guide angle φ is totally reflected at the interface with the outside and heads toward the second surface 2c without being emitted to the outside. The incident light L2 that reaches the second surface 2c at a light guide angle φ is totally reflected again at the interface with the outside and heads toward the first surface 2b, a part of which is refracted at the exit surface 4a of the prism portion 4 and emitted to the outside at an exit angle θ2, and the remaining part is totally reflected at the flat portion 3. Also, as shown in FIG. 3, for example, a portion of the incident light L2 from the incident surface 2a that first reaches the exit surface 4a of the prism portion 4 is refracted and emitted to the outside at an exit angle θ2. The portion of the incident light L2 that is repeatedly reflected by the flat portion 3 and the second surface 2c and does not reach the prism portion 4 finally reaches the third surface 2d, where the residual light L4 is refracted and emitted to the outside. As described above, the optical member 1 is configured such that in the light guide 2, the light is repeatedly emitted from the first surface 2b side of the light guide and totally reflected inside, thereby widening the viewing zone on the first surface 2b side, i.e., the area where the user can see the emitted light L3.

[0022] The "incident angle θ1" refers to the angle between the normal direction of the flat surface of the flat portions 3 of the first surface 2b (hereinafter referred to as the "flat portion normal direction") and the incident direction of the external scene light L1 to the incident surface 2a. The "light guide angle φ" refers to the angle between the traveling direction of the incident light L2 in the flat portion 3 and the flat portion normal direction, or the angle between the traveling direction of the incident light L2 in the second surface 2c and the normal direction to the second surface 2c. When the flat portion 3 and the second surface 2c are parallel, the light guide angle φ in the flat portion 3 and the second surface 2c has the same value regardless of the number of reflections. The "exit angle θ2" refers to the angle between the traveling direction of the exit light L3 and the flat portion normal direction, and has the same value as θ1 when the incident surface 2a and the exit surface 4a are parallel. The light guide angle φ is based on, for example, the light guide angle at the maximum incident angle of the external scene light L1 entering the light guide body 2. The maximum incidence angle of the external scene light L1 refers to the angle between a virtual line connecting the user's eye located on the first surface 2b side and the end point of the entrance surface 2a on the first surface 2b side, and the normal direction of the flat portion, as shown in Fig. 4. The reason for using the above as the criterion is that the external scene light L1 exceeding the maximum incidence angle includes light rays from an area that the user can directly view without passing through the light guide body 2.

[0023] The incident surface 2a of the light guide 2 is a surface on which the external light L1 is incident, and in this embodiment, it intersects with the first surface 2b. The incident surface 2a is inclined at an inclination angle ψ with respect to the normal direction of the flat portion. That is, in this embodiment, the incident surface 2a is inclined so that the angle between the incident surface and the flat surface is an acute angle. The inclination angle ψ of the incident surface 2a with respect to the normal direction of the flat portion is smaller than the light guide angle φ of the incident light L2 with respect to the flat portion 3 and the second surface 2c, as shown in FIG. 2, for example. At this time, if ψ<π / 2-φ according to the refraction condition, the incident light L2 is refracted in a direction in which φ is larger than the incident angle θ1 of the external light L1, and is guided to a wider range of the first surface 2b. Furthermore, since φ is the total reflection angle of the light guide 2, the refractive index of a normal light-transmitting resin material is 1.4 or more, so that φ>45.3 from n·sinφ>1, and the structure satisfies φ>ψ.

[0024] The first surface 2b of the light guide 2 is the surface where the incident light L2 from the incident surface 2a first reaches, and has a plurality of flat portions 3 and a plurality of prism portions 4. In this embodiment, the first surface 2b has a configuration in which the portion intersecting with the incident surface 2a is the prism portion 4, and the flat portions 3 and the prism portions 4 are alternately arranged toward the third surface 2d. The first surface 2b having the flat portions 3 and the prism portions 4 is formed, for example, by a known plastic molding method using a mold or the like.

[0025] The second surface 2c is a smooth surface substantially parallel to the first surface 2b. The second surface 2c functions as a reflecting surface that reflects the incident light L2 reflected by the flat portions 3 toward the first surface 2b by total reflection. In other words, the second surface 2c is a second reflecting surface that forms a pair with the flat portions 3 described below as the first reflecting surface.

[0026] The third surface 2d is a surface connecting the first surface 2b and the second surface 2c, and is, for example, an inclined surface inclined at a predetermined angle. A part of the incident light L2 that is repeatedly reflected by the flat portion 3 and the second surface 2c and does not reach the prism portion 4 escapes from the third surface 2d as afterglow L4. It is possible to prevent the emission of afterglow L4 by applying a light-shielding treatment such as disposing a light-absorbing film (not shown) on the third surface 2d. This makes it possible to suppress the occurrence of ghosts due to the leakage of afterglow L4.

[0027] 2 and 3, the flat portions 3 function as reflecting surfaces that reflect the incident light L2 that reaches the flat portions 3 toward the second surface 2c by total reflection. This allows the light guide 2 to guide the incident light L2 inside without having a semi-transparent mirror made of a metal or dielectric material, and prevents loss of the incident light L2 due to absorption in the flat portions 3. The flat portions 3 have a light guide direction along the flat surfaces from the incident surface 2a toward the third surface 2d, and a width in the light guide direction W. S The width W at which the reflectance of the incident light L2 on the first surface 2b becomes equal to or greater than a predetermined value is SSpecifically, the flat portions 3 of the first surface 2b are reflection portions of the incident light L2, and the prism portions 4 are absorption portions and emission portions of the incident light L2. Therefore, the reflectance R of the first surface 2b is W is determined by the ratio of the flat portion 3. The reflectance R of the first surface 2b W is the width W S The width of the prism portion 4 adjacent to the flat portion 3 in the light guide direction is W P This is expressed by the following equation (2).

[0028] R W =W S / (W P +W S ) · · · (2) The flat portions 3 are R W ≧0.5, that is, the width W at which the reflection of the incident light L2 on the first surface 2b is greater than or equal to the emission S , that is, W P / W S It is preferable that the width satisfies the condition ≦1. In this case, the light guide 2 guides half or more of the incident light L2 at the first surface 2b and emits the exit light L3 from a wider range of the first surface 2b, thereby ensuring the brightness of the exit light L3.

[0029] In addition, when the light guide 2 satisfies the above formula (1) and the light guide angle φ is the total reflection angle, the reflectance R W As shown in the above formula (2), the reflectance R of the light guide 2 is determined only by the ratio of the widths of the flat portion 3 and the prism portion 4. W Since this structure does not depend on the angle or wavelength of the incident light L2, changes in the color tone and brightness of the emitted light L3 are suppressed compared to conventional optical components that use semi-transparent mirrors.

[0030] The multiple prism portions 4 are disposed adjacent to the flat portion 3, protrude from the flat portion 3 to the outside, and have an exit surface 4a that emits a portion of the incident light L2 to the outside. The multiple prism portions 4 have a protruding shape having an exit surface 4a and an opposing surface 4b that faces the exit surface 4a and intersects with the exit surface 4a, and are similar to one another, as shown in Fig. 1, for example.

[0031] The exit surface 4a of the multiple prism parts 4 is approximately parallel to the entrance surface 2a. When the exit surface 4a is parallel to the entrance surface 2a, the exit angle θ2 of the exit light L3 from the exit surface 4a is the same as the entrance angle θ1, so that the optical member 1 can make the user on the first surface 2b side visually recognize the same light as the outside scene light L1. Note that, "approximately parallel" includes not only the case where the entrance surface 2a and the exit surface 4a are parallel, but also the case where the entrance surface 2a and the exit surface 4a are approximately parallel due to unavoidable errors due to the processing accuracy of the light guide 2. The same applies to "approximately parallel" in the following specification.

[0032] The facing surface 4b of the multiple prism parts 4 is inclined at an inclination angle δ with respect to the normal line of the flat part and intersects with the exit surface 4a, as shown in FIG. 2, for example. The facing surface 4b is covered with a light absorbing film 5, which suppresses reflection of the incident light L2 at the facing surface 4b and intrusion of external light from the first surface 2b side. This makes it possible to suppress ghosts in which external light from the first surface 2b side appears to overlap with the exit light L3, and noise caused by unintended reflected light of the incident light L2 at the facing surface 4b being emitted from the exit surface 4a. The light absorbing film 5 is made of any light-shielding resin material or metal material, and is formed by any process such as printing or deposition.

[0033] The inclination angle δ of the opposing surface 4b is equal to or larger than the emission angle θ2 of the emitted light L3, and equal to or larger than the incidence angle θ1 of the external scene light L1 when the incidence surface 2a and the emission surface 4a are parallel. As a result, the emitted light L3 is emitted to the outside without being blocked by the opposing surface 4b. In addition, it is preferable that the inclination angle δ of the opposing surface 4b is smaller than the light guide angle φ of the flat portion 3. This prevents the incident light L2 from being incident on the opposing surface 4b and interfering with it, and can suppress unintended reflection of the incident light L2 on the opposing surface 4b and noise resulting therefrom.

[0034] In addition, the width W of the flat portions 3 S and the width W of the plurality of prism portions 4 P are all the same, the reflected light is reflected by the prism width W PA gap is created, and the relationship between the gap and the prism portion 4 at the rear portion changes periodically, which may cause uneven brightness, i.e., moire. S and W P For example, it is preferable that the width W of the flat portions 3 in the light guide direction is within a predetermined range centered on a certain value, that is, has a distribution. S The average value W is expressed by the following formula Sa It is preferable that the value is within a predetermined range having a center value of

[0035]

number

[0036]

number

[0037] In the first surface 2b, the emergent light L3 is emitted only from the emergent surface 4a of the prism portion 4 at an emergent angle θ2. Therefore, the emergent light L3 reaching the user is incident on the prism portion 4 at an emergent angle θ2, which is the width W of the prism portion 4 as shown in FIG.P and the width W of the flat part 3 S The pitch P of the emitted light L3 from the user's viewpoint is E is expressed by the following equation (3).

[0038] P E =(W P +W S ) cosθ2 (3) The adjacent flat portion 3 and prism portion 4 are spaced apart from each other by a pitch P E Width W should be less than 2 mm. S , W P This is because the minimum pupil diameter of a human being in a bright place is 2 mm or more, and the pitch P of the emitted light L3 is E By setting the distance to less than 2 mm, the amount of emitted light L3 visually recognized by the user is averaged, and changes in brightness associated with movement of the user's viewpoint are suppressed.

[0039] The flat portions 3 and the second surface 2c do not necessarily need to be completely parallel, and may be in a form in which these surfaces are not parallel depending on the distance of the blind spot that is desired to be visually recognized by the user.

[0040] Specifically, when the flat portions 3 and the second surface 2c are parallel, the light guide angle φ of the incident light L2 is constant regardless of the position on the light guide 2, and therefore the emission angle θ2 of the emitted light L3 is constant. This state is the same as when a light ray from infinity enters a human eye, because the emitted light L3 with the same emission angle θ2 enters the user's eye even if the user's viewpoint position is different. In other words, when the blind spot area that is desired to be viewed by the user is located at a position at a distance of a predetermined distance or more (for example, tens to hundreds of meters) from the user, it is preferable that the flat portions 3 and the second surface 2c are parallel.

[0041] On the other hand, when one of the flat parts 3 and the second surface 2c is slightly inclined with respect to the other surface, the light guide angle φ of the incident light L2 changes depending on the position in the light guide 2. This state is the same as when a light ray enters a human eye from a finite distance of, for example, several meters to several tens of meters, since the exit angle θ2 of the exit light L3 changes depending on the user's viewpoint position. In other words, when the blind spot area that the user wants to view is located at a finite distance from the user that is less than a certain distance, the flat parts 3 and the second surface 2c are preferably not parallel. In this case, the flat parts 3 and the second surface 2c need to be arranged in a direction in which the distance between these two opposing surfaces increases as they move away from the entrance surface 2a, that is, in a direction in which these two surfaces open. This is because, when the flat parts 3 and the second surface 2c are arranged in the opposite direction, that is, in a direction in which the two surfaces close, the exit light L3 is emitted in a direction away from each other, and the image cannot be fused with both eyes of the human eye.

[0042] According to this embodiment, the first surface 2b, which is the first surface that the incident light L2 from the incident surface 2a reaches, is configured to have a plurality of flat portions 3 and prism portions 4, so that the optical member 1 is capable of guiding the incident light L2 without having a semi-transmitting mirror. This simplifies the manufacturing process and reduces the manufacturing cost compared to conventional optical members that have semi-transmitting mirrors. In addition, the light guide 2 is configured so that the incident light L2 is totally reflected by the flat portions 3 and the second surface 2c facing the flat portions 3, so that the absorption loss of light in the light guide 2 is suppressed. Furthermore, the reflectance R of the incident light L2 on the first surface 2b is W The width W of the adjacent flat portion 3 S and the width W of the prism part 4 P Since it is determined by the ratio of W does not depend on the wavelength or angle of the incident light L2. Therefore, the optical member 1 of the present embodiment can suppress changes in brightness and color tone of the outside scene viewed by the user through the first surface 2b while suppressing light loss in the light guide 2.

[0043] (Modification of the first embodiment) The optical member 1 of the first embodiment may be configured such that some of the prism portions 4 have a top surface 4c connecting the exit surface 4a and the opposing surface 4b, as shown in Fig. 5. In this case, the light absorbing film 5 is disposed so as to cover the top surface 4c, not the opposing surface 4b.

[0044] In this modification, the multiple prism parts 4 are trapezoidal in shape, with an exit surface 4a, an opposing surface 4b, and a top surface 4c, except for the prism part 4 closest to the entrance surface 2a. The multiple trapezoidal prism parts 4 are all aligned to the same height, with the height being the distance from the flat part 3 to the top surface 4c along the normal direction of the flat part. The top surface 4c of the multiple trapezoidal prism parts 4 is at the same height as the apex (the intersection of the exit surface 4a and the opposing surface 4b) of the prism part 4 closest to the entrance surface 2a. The top surface 4c of the multiple trapezoidal prism parts 4 is parallel to the second surface 2c.

[0045] The multiple trapezoidal prism portions 4 are configured such that even when incident light L2 is incident on the opposing surface 4b and is reflected at the opposing surface 4b, the reflected light travels toward the top surface 4c and is blocked by the light absorbing film 5.

[0046] Specifically, for example, as shown in Fig. 6, in a structure in which the exit surface 4a and the opposing surface 4b of a plurality of prism portions 4 are adjacent to each other and intersect, when the incident light L2 is incident on the opposing surface 4b, the incident light L2 is reflected by the opposing surface 4b, and the reflected light can be emitted from the exit surface 4a. The light of the incident light L2 that directly reaches the exit surface 4a and is emitted is referred to as the exit light L. 3a The reflected light from the opposing surface 4b is emitted from the exit surface 4a as light L 3b When emitted as 3a , L 3boverlap, causing noise. Even if the opposing surface 4b is inclined at an inclination angle δ (<light guide angle φ), the difference between the light guide angle φ and the inclination angle δ is generally about 10°, and it is difficult to provide a larger angle difference. In addition, when the incident light L2 with an incident angle close to 90° is incident on the opposing surface 4b, it is difficult to completely suppress the interface reflection and to block the reflected light with the light absorbing film 5, so that the reflected light escapes to the outside from the exit surface 4a. As a result, the prism section 4 having a structure in which the exit surface 4a and the opposing surface 4b are adjacent to each other and intersect may not be able to suppress the generation of noise caused by the opposing surface 4b.

[0047] In contrast, the trapezoidal prisms 4 have a top surface 4c between the exit surface 4a and the opposing surface 4b, and therefore the inclination angle of the opposing surface 4b is significantly shifted from the light guide angle φ. As a result, even if the incident light L2 is incident on and reflected by the opposing surface 4b, the reflected light travels toward the top surface 4c and does not reach the exit surface 4a, so that the exit light L 3b Therefore, it is possible to prevent noise caused by the above.

[0048] 7, the trapezoidal prism portion 4 has an angle ε between the virtual straight line VL1 connecting points V and P and the normal direction of the flat portion, which is larger than the emission angle θ2 of the emitted light L3. Point V is a first end point of the emission surface 4a of the prism portion 4 on the adjacent flat portion 3 side, and point P is a second end point of the top surface 4c of another prism portion 4 adjacent to the prism portion 4 on the opposing surface 4b side. This allows the emitted light L3 from a certain prism portion 4 to be emitted to the outside without being blocked by the opposing surface 4b of the adjacent prism portion 4, thereby suppressing loss of the emitted light L3 from the emission surface 4a.

[0049] This modified example also provides the optical member 1 with the same effects as those of the first embodiment. In addition, since the multiple prism portions 4 have a trapezoidal shape with a top surface 4c, it is possible to prevent noise generation caused by reflection of the incident light L2 on the opposing surface 4b of the prism portion 4.

[0050] Second embodiment The optical member 1 of the second embodiment will be described with reference to Fig. 8 and Fig. 9. In Fig. 9, in order to make it easier to understand the light guide in the optical member 1, external light L1 and incident light L 21 ~L 23 and the emitted light L 31 ~L 33 A part of these rays is shown and these rays are hatched.

[0051] 8, the optical member 1 of this embodiment differs from the above-described first embodiment in that the first surface 2b has three regions 2ba, 2bb, and 2bc, and the width ratios of the adjacent flat portions 3 and prism portions 4 between the regions 2ba, 2bb, and 2bc are different. In this embodiment, this difference will be mainly described.

[0052] In this embodiment, the first surface 2b is divided into a first region 2ba, a second region 2bb, and a third region 2bc, in that order from the incident surface 2a side, and the ratio of the width of the adjacent flat portion 3 and the prism portion 4 is different for each of these regions. Specifically, the width of the adjacent flat portion 3 and the prism portion 4 in the first region 2ba is W S1 , W P1 In the second region 2bb, the width of the adjacent flat portion 3 and prism portion 4 is W S2 , W P2 And, W S1 / W P1 W S2 / W P2 The third region 2bc is formed only of the prism portion 4, and the ratio of the width of the flat portion 3 to the width of the prism portion 4 is zero. In other words, the ratio of the width of the flat portion 3 to the width of the prism portion 4, i.e., W s / W p is getting smaller.

[0053] In other words, the flat portions 3 have a larger width in a region located closer to the incident surface 2a, and the width is zero in the region farthest from the incident surface 2a, i.e., the flat portions 3 are not arranged at all. The prism portions 4 are similar in shape and may have the same width and height in each region, or may have different widths and heights. In addition, the width W of the flat portions 3 and the prism portions 4 in the regions 2ba to 2bc is S , W P For example, as in the first embodiment, each of the widths W of the flat portions 3 and the prism portions 4 is set to a value within a predetermined range centered on a constant value (for example, the average value expressed by the formula 1 or 2). This makes it possible to suppress the occurrence of moire caused by the periodic structure of the flat portions 3 and the prism portions 4. Furthermore, since the period of the structure differs from region to region, the width W S , W P Even if the value of the pixel value is constant, the occurrence of moire can be suppressed.

[0054] Here, the first surface 2b is W s / W p The effect of being constituted by a plurality of regions with different thicknesses will be described below. For example, as shown in FIG. 9, a case in which external light L1 enters the light guide 2 and is reflected twice by the flat portion 3 will be described as a representative example.

[0055] For convenience of explanation, the portion of the incident light L2 from the incident surface 2a that first reaches the flat portion 3 is referred to as the “incident light L 21 " and the incident light L 21 The part of the light reflected by the flat portion 3 is called the "incident light L 22 " and the incident light L 22 The part of the light reflected by the flat portion 3 is called the "incident light L 23 " and " 21 The part of the light emitted from the prism portion 4 is called "emitted light L 31 " and the incident light L 22 The part of the light emitted from the prism portion 4 is called "emitted light L 32 " and the incident light L 23 The part of the light emitted from the prism portion 4 is called "emitted light L 33 " respectively.

[0056] When the ratio of the widths of the adjacent flat portions 3 and prism portions 4 is the same over the entire area of ​​the first surface 2b as in the first embodiment, the reflectance R W Therefore, the amount of incident light L2 decreases at a constant rate as the number of reflections increases due to light guiding. For example, the reflectance R W = 0.6, and the incident light L 21 When the incident light L is 100%, 22 For 100×0.6=60%, the emitted light L 31 The ratio is 100-60=40%. Also, the incident light L 23 For 60×0.6=36%, the emitted light L 32 For the incident light L, it is 60-36=24%. 23 The reflected portion of the light is 36 × 0.6 = 21.6%, and the emitted light L 33 For W, the result is 36-21.6=14.4%. s / W p When is constant, the amount of emitted light L3 decreases as the number of reflections increases, so that the position on the first surface 2b farther from the entrance surface 2a appears darker.

[0057] In contrast, in this embodiment, the first surface 2b is W s / W p Each region has a different reflectance R W For example, the reflectance R W 2 / 3, the reflectance R of the second region 2bb W 1 / 2, and the reflectance R of the third region 2bc W In this case, the incident light L 21 When the incident light L is 100%, 22 For 100×2 / 3 ≒ 67%, the emitted light L 31 For the incident light L, it is 100-67 ≒ 33%. 23 For , 67 × 1 / 2 ≒ 34%, the emitted light L 32 For the third region 2bc, the incident light L 23 Since all of the light emitted is 33The rate for W is about 33%. s / W p Different reflectances, i.e., R W By configuring the first surface 2b with a plurality of regions having different wavelengths, the emitted light L 31 ~L 33 This allows the light amounts to be averaged to be approximately the same, thereby reducing uneven brightness depending on the user's viewpoint position.

[0058] In the above, a case where the first surface 2b is composed of three regions 2ba to 2bc has been described as a representative example, but the present invention is not limited to this, and the first surface 2b may be composed of a plurality of regions, and may be two regions, or may be four or more regions. For example, when the maximum number of reflections of the incident light L2 on the second surface 2c is m times (m is a natural number of 1 or more), the first surface 2b is composed of m+1 regions. In this case, the first region, the second region, ..., the (m+1)th region are defined in order from the entrance surface 2a, and are represented by W S / W P becomes smaller from the first region toward the (m+1)th region, and becomes zero in the (m+1)th region. For example, when the first surface 2b is composed of four regions, the reflectance R W should be 3 / 4 in the first region, 2 / 3 in the second region, 1 / 2 in the third region, and 0 in the fourth region. Then, in the case of the first surface 2b divided into four, the amount of emitted light L3 in each region is 100×(1-3 / 4)=25% in the first region, 75×(1-2 / 3)=25% in the second region, 50×(1-1 / 2)=25% in the third region, and the remaining 25% in the fourth region. In this way, when the first surface 2b is composed of m+1 regions, the W of the kth region is Sk / (W Pk +W Sk ) to W Sk / (W Pk +W Sk By satisfying the relationship expressed as m+1-k / m+2-k, the amount of light L3 emitted in each region becomes uniform, where k is an integer between 1 and m, and the reflectance in the m+1 region is 0.

[0059] According to this embodiment, in addition to the same effects as those of the first embodiment, the optical member 1 has an effect of averaging the amount of light emitted from the first surface 2b, thereby ensuring brightness.

[0060] (Modification of the second embodiment) In the optical member 1 of the second embodiment, as shown in FIG. 10, the prism parts 4 may be trapezoidal in shape, except for the prism part 4 closest to the incident surface 2a and the prism part 4 in the third region 2bc farthest from the incident surface 2a. The trapezoidal prism part 4 has a top surface 4c between the exit surface 4a and the opposing surface 4b, and the top surface 4c is covered with a light absorbing film 5, as in the modified example of the first embodiment. In addition, the top surface 4c of the trapezoidal prism part 4 is parallel to the second surface 2c and has the same height as the apex of the other prism part 4 that does not have the top surface 4c. This suppresses the generation of noise caused by the reflection of the incident light L2 on the opposing surface 4b. In the region where the prism parts 4 are adjacent to each other, it is difficult to form a top surface 4c of a sufficient width in the prism part 4, so that only the prism parts 4 adjacent to the flat part 3 among the plurality of prism parts 4 are formed into a trapezoid shape having a top surface 4c.

[0061] According to this modification, the optical member 1 can obtain the same effects as those of the second embodiment, and can also obtain the effect of suppressing the generation of noise in the region having the trapezoidal prism portion 4.

[0062] Third embodiment The optical member 1 of the third embodiment will be described with reference to Fig. 11 to Fig. 16. In Fig. 13 and Fig. 14, the external light L1, the incident light L2, and the exiting light L3 are hatched to make it easier to understand the light guide in the optical member 1.

[0063] 11, the optical member 1 of this embodiment differs from the above-described first embodiment in that the light guide 2 has a fourth surface 6 between the incident surface 2a and the second surface 2c, and the fourth surface 6 protrudes from the second surface 2c. This difference will be mainly described in this embodiment.

[0064] In this embodiment, the light guide 2 has a fourth surface 6 connecting the incident surface 2a and the second surface 2c, and the fourth surface 6 protrudes outward from the second surface 2c. The distance between the second surface 2c and the flat portions 3 in the normal direction of the flat portions is defined as height T0, and the distance between the end of the incident surface 2a on the fourth surface 6 side and the flat portions 3 in the normal direction of the flat portions is defined as height T1. d As a result, the light guide 2 is T d >T0.

[0065] In the present embodiment, the light guide 2 has a fourth surface 6, so that the area of ​​the incident surface 2a is larger than that of the above-described embodiments, as shown in, for example, Fig. 12. Therefore, the light guide 2 has a large area where the incident light L2 from the incident surface 2a first reaches the first surface 2b, making it possible to guide more light and eliminating gaps in the light guide.

[0066] Here, the "light guiding gap" will be described with reference to FIG. 13. In the case where the light guide 2 does not have the fourth surface 6 and the incident surface 2a and the second surface 2c are adjacent to each other and intersect with each other, the emitted light L3 may be emitted through a plurality of flat portions 3 and a prism portion 4, as shown in FIG. 13. The large gap between the emitted light L3 through the plurality of flat portions 3 and the prism portion 4 is the "light guiding gap", and the light guiding gap is an area where the guided outside scene light L1 cannot be seen by the user. In other words, when the light guiding gap occurs, the continuity of the outside scene light L1 guided by the user on the first surface 2b, that is, the continuity of the display, cannot be ensured.

[0067] In contrast, in the optical member 1 of this embodiment, the light guide 2 has a fourth surface 6, and the height T dis greater than the height T0 of the second surface 2c. As a result, in the optical member 1, as shown in FIG. 14, for example, the incident light L2 reaches a wide area of ​​the first surface 2b, and the area of ​​the incident light L2 that is reflected by the flat portion 3 and reaches the second surface 2c first is also increased. No gap is generated between the area of ​​the first surface 2b where the incident light L2 reaches first and the area of ​​the first surface 2b where the light reflected by the flat portion 3 and the second surface 2c reaches again. As a result, as shown in FIG. 14, for example, the exit light L3 is emitted from all the prism portions 4 of the first surface 2b, and no gap is generated in the light guide. Therefore, the optical member 1 of this embodiment has a structure in which no gap is generated in the light guide and the continuity of the display is ensured.

[0068] The fourth surface 6 is covered with a light absorbing film 5 to prevent the intrusion of unintended external light and the occurrence of ghost images due to interface reflection. Specifically, when a light ray is incident on the incident surface 2a at an angle smaller than the incident angle θ1, a part of the light ray reaches the fourth surface 6. The light absorbing film 5 absorbs the light that reaches the fourth surface 6 in this manner, and prevents unintended light, such as light reflected at a portion other than the second surface 2c, from traveling toward the first surface 2b, thereby suppressing the occurrence of ghost images.

[0069] The fourth surface 6 is an inclined surface that linearly connects an end of the incident surface 2a and an end of the second surface 2c as shown in Fig. 11. The fourth surface 6 is designed such that the inclination angle ξ with respect to the normal direction of the flat portion does not cause a "gap in the light beam" when the incident light L2 from the incident surface 2a is guided.

[0070] Specifically, for example, as shown in FIG. 15, when the inclination angle ξ of the fourth surface 6 is larger than the light guide angle φ of the incident light L2, a gap between the light rays may occur.

[0071] For the sake of convenience, the end of the incident surface 2a on the second surface 2c side will be referred to as the "first end 2aa," and the portion of the incident light that is incident from the vicinity of the first end 2aa will be referred to as the "incident light L 2aIn addition, the end of the second surface 2c on the side of the incident surface 2a is referred to as the "second end 2ca", and the portion of the incident light reflected in the vicinity of the second end 2ca is referred to as the "incident light L 2b " It is called.

[0072] When the inclination angle ξ of the fourth surface 6 is greater than the light guide angle φ, the incident light L 2a passes through a position away from the second end 2ca, and the incident light L reflected near the second end 2ca 2b A gap is created between the incident light L 2a and the incident light L 2b The gap between the first surface 2b and the prism portion 4 is called a "light beam gap." When this light beam gap occurs, the incident light L2 may not reach some of the prism portions 4 constituting the first surface 2b. In this case, a light guide gap occurs, and it becomes impossible to ensure the continuity of the display.

[0073] Therefore, the fourth surface 6 is configured to satisfy the relationship of the inclination angle ξ<the light guide angle φ. In this case, as shown in FIG. 2a passes through the vicinity of the second end 2ca, and the incident light L 2b As a result, no gap is generated between the light guide 2 and the first surface 2b of the optical member 1, and no gap is generated in the light guide, so that the optical member 1 can ensure continuity of display on the first surface 2b.

[0074] In addition, when the incident angle θ1 of the external light L1 is θ1±Δθ1 and the light guide angle φ of the incident light L2 has a range of φ±Δφ, the fourth surface 6 can suppress the occurrence of gaps between the light rays within the range of θ1±Δθ1 by satisfying the inclination angle ξ<φ-Δφ.

[0075] In the above, the fourth surface 6 is an inclined surface, and the inclination angle ξ is smaller than the light guide angle φ. However, the fourth surface 6 is not limited to a single inclined surface, and may have a configuration having multiple surfaces or a curved surface. For example, the fourth surface 6 may have a rectangular shape having two surfaces as shown in FIG. 17. In this way, when the fourth surface 6 is configured as a configuration other than a single inclined surface, the fourth surface 6 is not particularly limited in its outer shape as long as the incident light L2 incident from the vicinity of the first end 2aa passes through the vicinity of the second end 2ca. Specifically, the inclination angle ξ can be said to be the angle between the virtual straight line VL2 connecting the first end 2aa and the second end 2ca and the normal direction of the flat portion, as shown in FIG. 16 and FIG. 17. Therefore, the fourth surface 6 may have any shape as long as it satisfies ξ<φ, but regardless of the shape, the region from the first end 2aa to the second end 2ca is covered with the light absorbing film 5.

[0076] Incidentally, it is preferable that the inclination angle ψ of the incident surface 2a is smaller than π / 2-θ1. When the incident surface 2a, which is a refracting surface of the external scene light L1, satisfies ψ<π / 2-θ1, the light guide angle φ of the refracted incident light L2 becomes larger than the incident angle θ1 of the external scene light L1. As a result, the light guide body 2 can be configured such that the initial arrival width of the incident light L2 is wider and the light guide width, i.e., the height T0 of the second surface 2c, is smaller than when the light guide angle is assumed to be θ1.

[0077] According to this embodiment, in addition to the same effects as those of the first embodiment, the optical member 1 has an advantage that no gap is generated in the light guide and continuity of the display on the first surface 2b can be ensured.

[0078] (Modification of the third embodiment) 18, the optical member 1 of the third embodiment may be configured such that the first surface 2b has a prism region 2bp consisting only of a prism portion 4. The optical member 1 may be configured such that the third surface 2d is an inclined surface that is continuous with the exit surface 4a of the prism portion 4 that is closest to the third surface 2d among the multiple prism portions 4. In other words, the third surface 2d, i.e., the end surface of the light guide 2, is parallel to the entrance surface 2a together with the exit surface 4a.

[0079] For example, as shown in FIG. 19, the width of the light guide 2 in the light guide direction is L a The width in the light guide direction from the end of the first surface 2b on the side of the incident surface 2a to the prism region 2bp is L b In this modification, the light guide 2 is configured to satisfy the following expressions (4) and (5).

[0080] L a =(2N-1)×T0×tanφ (4) L b = 2N × T0 × tanφ (5) In the formulas (4) and (5), N is a positive integer. When the light guide 2 satisfies the formulas (4) and (5), the end of the incident light L2 that reaches the second surface 2c after being repeatedly reflected by the first surface 2b (L in FIG. 19) 22 ) coincides with the upper end of the third surface 2d, which is the end surface. As a result, only the light reflected by the second surface 2c is incident on the third surface 2d, while the light reflected by the first surface 2b is not incident on the third surface 2d. In other words, the light emitted from the third surface 2d is emitted only to the first surface 2b side, and is not emitted to the second surface 2c side. Therefore, the light guide 2 can emit the guided light in the viewing direction of the user without waste.

[0081] In addition to satisfying the above formula, the first surface 2b has a thickness L a By making the portion exceeding the prism region 2bp, all of the incident light L2 that reaches the prism region 2bp can be emitted in the direction of the user's view. aTherefore, the number of prism portions 4 exceeding this range can be minimized, and the length of the light guide 2 in the light guide direction can be reduced.

[0082] In addition, L a may be within the range of ±10% of the value represented by (2N-1) × T0 × tanφ. b may be within the range of ±10% of the value indicated by 2N × T0 × tanφ. This is because a deviation of about 10% may occur depending on the angle of the incident light, and L a , L b If is within the above range, the effect of minimizing the loss of light guided is expected.

[0083] According to this modification, the optical member 1 has an effect of suppressing loss of guided light in addition to the effects of the third embodiment. Moreover, the optical member 1 has a configuration in which the length of the light guide 2 in the light guide direction is minimized.

[0084] (Fourth embodiment) An optical member 1 of a fourth embodiment will be described with reference to Fig. 20 to Fig. 23. In Fig. 22 and Fig. 23, the outside light L1 and the incident light L2 are hatched, and the part of the outside light L1 that is incident on the light guide 2 and the part that is not incident thereon are indicated by different hatching.

[0085] 20, the optical member 1 of this embodiment differs from the above-described first embodiment in that an outer surface of the light guide 2 that connects the first surface 2b and the second surface 2c, and that is a surface opposite to the third surface 2d, serves as an entrance portion 8 made up of a plurality of second prism portions 7. In this embodiment, this difference will be mainly described.

[0086] In this embodiment, the light guide 2 has an area between the first surface 2b and the second surface 2c, which is located on the opposite side to the third surface 2d, as the incident portion 8. The incident portion 8 is composed of a plurality of second prism portions 7, with the plurality of prism portions 4 constituting the first surface 2b being referred to as "first prism portions."

[0087] The second prism portions 7 each have a first surface 7a corresponding to the entrance surface 2a and a second surface 7b adjacent to and intersecting with the first surface 7a. The second prism portions 7 are adjacent to each other and arranged in parallel along a direction connecting the first surface 2b and the second surface 2c.

[0088] For ease of explanation, the direction connecting first surface 2b and second surface 2c, ie, the direction along the arrangement direction of the plurality of second prism portions 7, will be referred to as the "prism arrangement direction" hereinafter.

[0089] As shown in FIG. 21, for example, the angle ω between the prism arrangement direction and the normal direction to the flat portion of the second prism portions 7 is equal to or smaller than the light guide angle φ.

[0090] The first surface 7a of each of the second prism portions 7 is substantially parallel to the exit surface 4a of the first surface 2b. As shown in Fig. 21, the first surface 7a forms an angle ψ with the normal direction of the flat portion, and ψ is set to be approximately the same as the inclination angle of the entrance surface 2a in each of the above embodiments.

[0091] In the second prism portions 7, the angle σ between the plane of the second surface 7b and the normal direction of the flat portion is preferably equal to or larger than the incident angle θ1 of the external scene light L1 and equal to or smaller than the light guide angle φ of the incident light L2, i.e., θ1≦σ≦φ. This is to prevent gaps from occurring between the light beams incident from the first surface 7a.

[0092] Specifically, when σ<θ1, as shown in FIG. 22, for example, part of the outside light L1 incident from the first surface 7a of a second prism portion 7 reaches between the apex and valley of the second prism portion 7 and escapes to the outside. Also, because part of the outside light L1 is blocked by the adjacent second prism portion 7, the outside light L1 does not reach the entire first surface 7a of the multiple second prism portions 7, except for the second prism portion 7 located closest to the first surface 2b. As a result, the incident light from the first surface 7a of one second prism portion 7 is not reflected as the incident light L 2aThe light incident on the first surface 7a of the second prism portion 7 adjacent to the one second prism portion 7 is defined as the incident light L 2b As the incident light L 2a , L 2b In this case, gaps will occur in the light incident from the first surface 7a, and periodic light rays will reach the first surface 2b, which may cause moire.

[0093] On the other hand, when θ1≦σ≦φ is satisfied, as shown in FIG. 23, for example, part of the outside light L1 enters through the first surface 7a of a certain second prism portion 7, reaches between the apex and valley of the second prism portion 7, and escapes to the outside. However, when θ1≦σ≦φ is satisfied, the proportion of this light escaping to the outside is smaller than when σ<θ1. Also, the outside light L1 reaches the entire first surface 7a of the multiple second prism portions 7 without being blocked by adjacent second prism portions 7. As a result, the incident light L from a certain second prism portion 7 2a and the incident light L from the adjacent second prism portion 7. 2b No gap is generated between the two, and the occurrence of moire can be suppressed.

[0094] For example, as shown in FIG. 23, when the height of the second prism portion 7 along the normal to the flat portion is h and ω=φ is satisfied, the maximum height of the incident portion 8 along the normal to the flat portion is T0+h.

[0095] According to this embodiment, the optical member 1 can obtain the same effects as those of the first embodiment.

[0096] Fifth embodiment The optical member 1 of the fifth embodiment will be described with reference to Fig. 24 to Fig. 27. In Fig. 25 to Fig. 27, in order to make it easier to understand the light guide in the optical member 1, a portion of the external light L1, the incident light L2, and the exiting light L3 are shown, and these light rays are hatched.

[0097] 24, the optical member 1 of this embodiment differs from the above-described first embodiment in that the light guide 2 is adjacent to the second surface 2c, has an incident portion 8 disposed opposite the first surface 2b together with the second surface 2c, and has a fifth surface 2e connecting the incident portion 8 and the first surface 2b. In this embodiment, this difference will be mainly described.

[0098] In this embodiment, the light guide 2 has an incident portion 8 whose prism arrangement direction is along the plane of the second surface 2c, and a fifth surface 2e is formed between the incident portion 8 and the first surface 2b. As in the fourth embodiment, the incident portion 8 is made up of a plurality of second prism portions 7 arranged adjacent to each other and in parallel. Moreover, the first surfaces 7a of the plurality of second prism portions 7 are substantially parallel to the exit surface 4a of the first surface 2b.

[0099] In this embodiment, the entrance portion 8 is configured such that the valleys of the second prism portions 7 are located on the plane of the second surface 2c. That is, the entrance portion 8 is arranged such that the virtual plane of the valleys of the second prism portions 7 is parallel to the flat portions 3. As a result, the optical path length of the light beam that first reaches the first surface 2b from the entrance portion 8 is the same regardless of the position in the entrance portion 8, so that the distortion of the outside scene image visually recognized by the user due to the exit light L3 is minimized. Note that the optical path length when the incident light L2 incident from the entrance portion 8 is reflected by the flat portion 3 and reaches the second surface 2c, and the optical path length when the incident light L2 reflected by the second surface 2c reaches the first surface 2b are also constant.

[0100] The width of the incident portion 8 in the light guide direction is W I From the viewpoint of minimizing the gap of the light guide on the first surface 2b while suppressing the light loss, W I It is preferable that the following formula (6) is satisfied.

[0101] W I = 2T0 × tanφ (6) W I25, for example, in the case of the light guide 2, the area of ​​the region of the first surface 2b where the incident light L2 first arrives from the incident portion 8 becomes small. As a result, a light guide gap is generated between the emitted light L3 from the region where the incident light L2 first arrives at the first surface 2b and the emitted light L3 that is emitted after the incident light L2 is reflected once by the flat portion 3 and once by the second surface 2c and arrives at the first surface 2b.

[0102] W I When >2T0×tanφ, the light guide 2 has a configuration in which the area of ​​the region on the first surface 2b where the incident light L2 from the incident portion 8 first arrives becomes large, as shown in FIG. 26, for example, and no gaps in the light guide as described above occur. However, as a result of the region on the second surface 2c side where the reflected light from that region arrives becoming larger, a portion of the light reflected from the region on the first surface 2b where the incident light L2 from the incident portion 8 first arrives reaches the incident portion 8. Since the incident portion 8 does not have a reflective surface on the first surface 2b side, when the incident light L2 from the first surface 2b side reaches the incident portion 8, the reaching light escapes to the outside. In this way, W I If >2T0×tanφ, a light loss occurs in which the light passes through the incident portion 8 to the outside.

[0103] W I When W = 2T0 × tanφ, the light guide 2 has a configuration in which the area of ​​the region on the first surface 2b where the incident light L2 from the entrance portion 8 first reaches becomes large, while the reflected light from that region reaches only the second surface 2c, as shown in Fig. 27 for example. As a result, no gaps are generated between the emitted light L3 from the first surface 2b, which are separated by a plurality of flat portions 3 and prism portions 4, and the loss of light from the entrance portion 8 is suppressed. Note that a deviation of about 10% can occur depending on the angle of the incident light, so W I If is within the range of ±10% of the value expressed by 2T0×tanφ, the light guide 2 has a configuration in which the above-mentioned light loss and the influence of gaps in the light guide are reduced.

[0104] According to this embodiment, the optical member 1 has the same effect as that of the first embodiment. Moreover, in this optical member 1, the incident portion 8 and the first surface 2b are arranged substantially parallel to each other, and the optical path length in the light guide 2 is constant regardless of the position of the incident portion 8, so that the optical member 1 is not affected by the arrangement of the light guide 2. For example, even if the light guide 2 is rotated around an axis in a direction other than the normal direction of the flat portion, the light beam that is horizontally incident on the incident portion 8 is emitted horizontally from the first surface 2b as it is, so that the optical member 1 is not affected by the arrangement of the light guide 2, i.e., the mounting posture.

[0105] (Other embodiments) Although the present disclosure has been described based on the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, and other combinations and forms including only one element, more than one, or less than one, are also within the scope and concept of the present disclosure.

[0106] For example, in the optical member 1 of the third to fifth embodiments, a part of the prism portions 4 constituting the first surface 2b may be a trapezoid having a top surface 4c. Also, in the optical member 1 of the fourth and fifth embodiments, the width W S and the width W of the prism part 4 P In this manner, the optical member 1 is not limited to the above-described embodiments and their modifications, and may be in any combination except in cases where they are clearly incompatible. [Explanation of symbols]

[0107] 2...Light guide, 2a...Incidence surface, 2aa...First end, 2ca...Second end, 2b...first surface, 2c...second surface, 3...flat portion, 4...prism portion, 4a: exit surface, 4b: opposing surface, 5: light absorbing film, 7: second prism portion, 7a...Incidence surface, 8...Incidence part

Claims

1. An optical member attached to a member that generates a blind spot, which internally reflects and guides external light, including light from the blind spot, The light guide (2) has an incident surface (2a, 7a) on which the external scene light is incident, a plurality of flat portions (3) and a plurality of prism portions (4), a first surface (2b) on which the incident light incident from the incident surface first reaches, and a second surface (2c) disposed opposite the plurality of flat portions, the flat portions are first reflecting surfaces that reflect the incident light toward the second surface by total reflection, the second surface is a second reflecting surface that reflects the light reflected by the flat portion toward the first surface by total reflection, The plurality of prism portions each have an exit surface (4 a) that emits a portion of the incident light or a portion of the light reflected by the second surface to the outside, the first surface has a plurality of regions in which the ratio of the width of the prism portion to the width of the flat portion adjacent to each other is different, a ratio of a width of the prism portion to a width of the flat portion is constant in each of the plurality of regions, and a ratio of a width of the flat portion to a width of the prism portion is smaller in the region located farther from the entrance surface, An optical member, wherein the width of the flat portion is zero in the region of a predetermined width located farthest from the incident surface among the plurality of regions, and the optical member is composed only of a plurality of prism portions.

2. When the number of the regions is m+1 (m: a natural number equal to or greater than 1), the width of the prism portion and the flat portion in the kth region from the entrance surface (1≦k≦m) among the regions is W Ｐｋ , W Ｓｋ As, W Ｓｋ / (W Ｐｋ +W Ｓｋ 2. The optical member according to claim 1, wherein m=(m+1−k) / (m+2−k).

3. The angle between the normal direction to the surface of the flat portions and the opposing surface (4b) of the plurality of prism portions is δ, and the angle between the normal direction and the opposing surface of the plurality of prism portions is θ. ２ Then, δ ≥ θ ２ The optical member according to claim 1 or 2, which satisfies the above.

4. An optical element that internally reflects and guides external scene light, The light guide (2) has an incident surface (2a, 7a) on which the external scene light is incident, a plurality of flat portions (3) and a plurality of prism portions (4), a first surface (2b) on which the incident light incident from the incident surface first reaches, and a second surface (2c) disposed opposite the plurality of flat portions, the flat portions are first reflecting surfaces that reflect the incident light toward the second surface by total reflection, the second surface is a second reflecting surface that reflects the light reflected by the flat portion toward the first surface by total reflection, The plurality of prism portions each have an exit surface (4 a) that emits a portion of the incident light or a portion of the light reflected by the second surface to the outside, At least a part of the prism portions among the plurality of prism portions has a trapezoid shape having a top surface (4c) adjacent to the exit surface, An end point of the exit surface of the trapezoidal prism portion on the side of the adjacent flat portion is defined as a first end point (V), an end point of the top surface of the adjacent trapezoidal prism portion on the opposite side to the exit surface is defined as a second end point (P), an angle between a virtual line connecting the first end point and the second end point and a line along a normal direction to the surface formed by the flat portion is defined as ε, and an angle between the exit light emitted to the outside from the exit surface and the normal direction is defined as θ. ２ As, The trapezoidal prism portion has a diameter ε>θ ２ Optical components that meet the above requirements.

5. The angle of incidence of the incident light with respect to the surface formed by the flat portions and the angle of incidence of the light reflected by the flat portions with respect to the second surface are denoted by φ, and the refractive index of the light guide is denoted by n １ The refractive index of the medium in contact with the light guide is n ２ As, The light guide has a relationship of sinφ>n ２ / n １ The optical member according to claim 1 , which satisfies the following:

6. The angle between the incident direction of the external light on the incident surface and the normal direction to the plane of the flat portion is defined as θ １ and the angle between the incident surface and the normal direction is ψ. The light guide has a relationship of φ>θ １ and π / 2−φ>ψ.

7. The plurality of prism portions arranged on the first surface are defined as first prism portions, and the light guide has an entrance portion (8) constituted by a plurality of second prism portions (7), 7. The optical member according to claim 1, wherein the entrance surface is a first surface (7a) of an outer surface of each of the plurality of second prism portions that is parallel to the exit surface of the first prism portion.

8. The optical member according to claim 7 , wherein the incident portion is disposed on a plane defined by the second surface.

9. The normal direction to the plane of the flat portion is defined as the flat portion normal direction, the end point of the incident surface located on the opposite side to the first surface is defined as a first end portion (2aa), and the distance along the flat portion normal direction between the first end portion and the plane of the flat portion is defined as a height T ｄ The distance between the flat portion and the second surface along the normal direction of the flat portion is defined as height T ０ As, The entrance surface is T ｄ >T ０ Fulfilling An end point of the second surface on the side of the incident surface is defined as a second end (2ca), an angle between a virtual line connecting the first end and the second end and a line along the normal direction of the flat portion is defined as ξ, and an incident angle of the incident light with respect to the surface defined by the flat portion is defined as φ, The optical member according to claim 1 , wherein the light guide satisfies ξ<φ.

10. The optical member according to claim 9 , wherein the light guide is covered with a light absorbing film (5) in a region from the first end to the second end.

11. The width of the incident surface is W Ｉ The normal direction to the plane of the flat portion is defined as the flat portion normal direction, and the distance between the flat portion and the second surface along the flat portion normal direction is defined as height T ０ and the incident angle of the incident light with respect to the plane of the flat portion is φ. the first surface has a plurality of regions in which the ratio of the width of the prism portion to the width of the flat portion adjacent to each other is different, The width of the plurality of regions is W Ｉ = 2T ０ 11. The optical member according to claim 1, wherein the difference is within ±10% of the value represented by tan φ.

12. The optical member according to claim 1 , wherein the flat portions are parallel to the second surface.

13. The optical member according to claim 1 , wherein the exit surface is parallel to the entrance surface.

14. The widths of the adjacent prism portions and flat portions are each W Ｐ , W Ｓ The angle between the incident direction of the external light to the incident surface and the normal direction to the plane of the flat portion is defined as θ １ As, The first surface is (W Ｐ +W Ｓ ) cosθ １ The optical member according to claim 1 , wherein the thickness satisfies the range of 1 mm to 2 mm.

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