Light guide member

Abstract

To provide a light guide member capable of reducing the thickness while avoiding an increase in the number of reflections and an increase in the discontinuity of a visible image.SOLUTION: The light guide member includes an incident part 10, an output part 21, a reflection part 30, and an inclination part 40. The internal reflection angle φ inside the reflection part and output part is larger than the incident angle θ of outside light. The first inclination angle ψ of the incident part 10 with respect to the first normal l1 is smaller than the internal reflection angle φ. The height Td from the output part 21 to a second side 10b is larger than the interval T between the output part 21 and the reflection part 30. The second inclination angle ξ of the inclination part 40 with respect to the first normal l1 is smaller than the internal reflection angle φ.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a light guiding member that guides light from an outside scene. [Background technology]

[0002] The blind spot assistance device described in Patent Document 1 includes a semi-transparent mirror and a reflective mirror. The blind spot assistance device reflects light from a blind spot area back and forth between the semi-transparent mirror and the reflective mirror, and emits it toward a user. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-143087 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the blind spot assistance device, when the distance between the semi-transparent mirror and the reflecting mirror is narrowed, the number of reflections increases, resulting in a decrease in image quality and an increase in discontinuity in the visual image. For this reason, it is difficult to make the blind spot assistance device thinner. One aspect of the present disclosure provides an optical light guide member that can be made thin while avoiding an increase in the number of reflections and an increase in discontinuity in a visual image. [Means for solving the problem]

[0005] A light guide member according to one aspect of the present disclosure includes an incident portion (10, 11), an exit portion (21, 22), a reflecting portion (30), and an inclined portion (40). The incident portion has a first side (10a) and a second side (10b) facing the first side, and is configured to receive external light from an external scene. The exit portion is in contact with the first side so as to be inclined with respect to the incident portion, and is configured to transmit a part of the incident external light and reflect another part. The reflecting portion is disposed parallel to the exit portion at a distance from the exit portion, and is configured to reflect the incident external light. The inclined portion connects the second side and the side of the reflecting portion on the incident portion side. The internal reflection angle (φ) inside the reflecting portion and the exit portion is configured to be larger than the incident angle (θ) of the external light at the light guide cross section. The light guide cross section corresponds to a plane defined by a first normal (l1) to the exit portion and a second normal (l2) to the incident portion. A first tilt angle (ψ), which is the tilt angle of the incident portion with respect to the first normal, is configured to be smaller than the internal reflection angle. A height (Td) from the exit portion to the second side in the direction of the first normal is configured to be larger than the distance (T) between the exit portion and the reflecting portion. A second tilt angle, which is the tilt angle of the tilt portion with respect to the first normal, is configured to be smaller than the internal reflection angle.

[0006] In the light guide member according to one aspect of the present disclosure, the internal reflection angle is larger than the incident angle of external light, so that the number of internal reflections is suppressed while the light guide member can be thinned. In addition, the first inclination angle and the second inclination angle are smaller than the internal reflection angle, and the height from the exit portion to the second side is larger than the distance between the exit portion and the reflecting portion, so that the continuity of the visual image can be ensured. Therefore, it is possible to avoid discontinuity of the visual image and an increase in the number of reflections, and to realize a light guide member that can be thinned. [Brief description of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view of a light guide illustrating a configuration of a light guide member according to a first embodiment. [Diagram 2] 3A and 3B are diagrams illustrating a configuration of an emission portion of the light guide member according to the first embodiment. [Diagram 3] 11A and 11B are diagrams illustrating the guide of outside scene light rays at a central angle of view in a light guide member according to a reference example. [Figure 4]13A and 13B are diagrams illustrating the guide of outside scene light rays at a field angle smaller than the central field angle in a light guide member according to a reference example. [Diagram 5] FIG. 11 is a diagram showing the thickness of a light-guiding member when the angle of incidence and the angle of internal reflection are equal. [Figure 6] 11 is a diagram showing the thickness of a light guiding member when the internal reflection angle is larger than the incidence angle. FIG. [Figure 7] 13 is a diagram showing an incident angle, a first inclination angle, an incident angle, and an internal reflection angle in a light guide member according to a reference example. FIG. [Figure 8] 13 is a diagram showing the relationship between the second inclination angle of the light guide member according to the reference example and the continuity of the visual image. FIG. [Figure 9] 13A and 13B are diagrams illustrating light guided at a maximum incident angle in a light guide member according to a reference example. [Figure 10] 10 is a cross-sectional view of a light guide illustrating a configuration of a light guide member according to a second embodiment. FIG. [Figure 11] 13 is a diagram showing a configuration of an emission unit according to a second embodiment. FIG. [Figure 12] 11 is a cross-sectional view of a light guide illustrating a configuration of a light guide member according to a third embodiment. FIG. [Figure 13] 13A and 13B are diagrams illustrating configurations of an entrance section and an exit section according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. 1. First embodiment <1-1. Configuration> The configuration of an optical light guide member 101 according to this embodiment will be described with reference to Fig. 1 and Fig. 2. The optical light guide member 101 includes an incident portion 10, an exit portion 21, a reflecting portion 30, an inclined portion 40, a terminal portion 50, and a light-transmitting member 60. The incident portion 10, the exit portion 21, the reflecting portion 30, the inclined portion 40, the terminal portion 50, and the light-transmitting member 60 are formed of a light-transmitting resin material.

[0009] The incident portion 10 is a surface having a first side 10a and a second side 10b, and light L from an external scene is incident thereon at an incident angle θ. The exit portion 21 is in contact with the first side 10a so as to be inclined with respect to the incident portion 10. The exit portion 21 transmits a part of the light L incident thereon, and reflects another part at an internal reflection angle φ. Here, a surface defined by a normal line (hereinafter, a first normal line) l1 of the exit portion 21 and a normal line (hereinafter, a second normal line) l2 of the incident portion 10 is referred to as a light guiding cross section. FIG. 1 shows a light guiding cross section of a light guiding member 101.

[0010] The incident section 10 is inclined at a first inclination angle ψ with respect to the first normal line l1. The first side 10a and the second side 10b are perpendicular to the light guiding cross section. The second side 10b is separated from the exit section 21 by a height Td.

[0011] The reflecting portion 30 is a surface that is disposed parallel to the emitting portion 21 and spaced apart from the emitting portion 21. The reflecting portion 30 is spaced apart from the emitting portion 21 by a light guide width T. The reflecting portion 30 totally reflects the light L that is incident on the reflecting portion 30. Therefore, the internal reflection angle φ is expressed as follows: φ>sin -1 It is constructed to satisfy the (1 / n) condition.

[0012] The inclined portion 40 is a surface that connects the second side 10b and the side of the reflecting portion 30 on the incident portion 10 side. The inclined portion 40 is inclined at a second inclination angle ξ with respect to the first normal line l1. A light absorbing film is disposed on the inclined portion 40. The light absorbing film suppresses reflection of the light L that reaches the inclined portion 40.

[0013] The light absorbing film arranged on the inclined portion 40 suppresses the reflection of light rays that enter the entrance portion 10 in FIG. 1 but do not reach the exit portion 21 (i.e., light rays that enter the white portion above the upper dotted incident light ray that passes through Pa) that directly reach the inclined portion 40, thereby suppressing the occurrence of ghost images.

[0014] The terminal end portion 50 is a surface that connects the emission portion 21 and the reflection portion 30. The light-transmitting member 60 fills the inside surrounded by the emission portion 21, the reflection portion 30, the inclined portion 40, and the terminal end portion 50. That is, the light-guiding member 101 has a solid structure.

[0015] The emission unit 21 includes a transmission / reflection surface 210 and a prism array 211. The transmission / reflection surface 210 is provided in contact with the light-transmitting member 60 and parallel to the reflection unit 30. The transmission / reflection surface 210 reflects a part of the light L incident on the transmission / reflection surface 210 and transmits another part.

[0016] The prism array 211 is provided on the outer surface of the transmission-reflection surface 210, and includes a plurality of arranged prisms 211a. The prism array 211 converts the angle of the light L transmitted through the transmission-reflection surface 210 by a refraction action and emits the light. Specifically, the prism array 211 converts the incident angle φ into an emission angle θ by a refraction action. As a result, the angle of the light L emitted from the emission unit 21 becomes equal to the incident angle θ of the light L to the light guide member 101. Therefore, a visual image of the outside scene is displayed in the direction in which the outside scene actually exists. The prism array 211 may be changed to a prism sheet in which a plurality of prisms 211a are arranged, or may be changed to another periodic structure.

[0017] Each prism 211a includes an emission side surface 211b and an emission facing surface 211c facing the emission side surface 211b. Light L incident on the prism array 211 is emitted from the emission side surface 211b, and is not emitted from the emission facing surface 211c.

[0018] The emission side surface 211b is inclined at a third inclination angle ψ with respect to the first normal line l1. The third inclination angle ψ is equal to the first inclination angle ψ. That is, the emission side surface 211b is parallel to the incident portion 10. A light absorbing film is disposed on the emission facing surface 211c. This makes it possible to prevent external light reaching the emission portion 21 from the outside of the emission portion 21 from entering through the emission facing surface 211c or being reflected by the emission facing surface 211c. As a result, it is possible to prevent noise light from being mixed into the light L from the outside scene. Furthermore, it is possible to prevent noise light from being mixed in due to reflection of the emission light ray reaching the emission facing surface 211c from the inside of the prism.

[0019] The light guiding member 101 is configured so that the incident angle θ, the internal reflection angle φ, the first inclination angle ψ, the second inclination angle ξ, the light guiding width T, and the height Td satisfy predetermined conditions. The predetermined conditions are relationships for suppressing an increase in the number of reflections and discontinuity of a visual image inside the light guiding member 101, suppressing ghost images, and making the light guiding member 101 thinner. The predetermined conditions are described below.

[0020] The incident angle θ of light L from outside may be in the range of θ1-θ2 to θ1+θ2. FIG. 3 shows the guide of a light ray with a central angle of view θ1 among the angles of incidence θ1-θ2 to θ1+θ2. Meanwhile, FIG. 4 shows the guide of a light ray with a minimum angle of view θ1-θ2 among the angles of incidence θ1-θ2 to θ1+θ2. As shown in FIG. 4, when a light ray with an angle of view θ1-θ2 is incident on the light guide member 300 according to the reference example, the light ray incident on the transmission-reflection surface 120 reaches the transmission-reflection surface 120 and is reflected at an internal reflection angle φ1-φ2. At this time, if the inclination angle ψ of the incidence surface 110 is in a relationship of ψ>φ1-φ2, the light ray incident on the end portion close to the transmission-reflection surface 120 reaches the incidence surface 110 before reaching the reflection surface 130 after being reflected by the transmission-reflection surface 120, and is totally reflected by the incidence surface 110. Therefore, the optical path of the round-trip reflection changes depending on the incident position on the incident surface 110. As a result, in addition to the light ray with the normal internal reflection angle φ1-φ2, a light ray with an internal reflection angle φ1+φ2 is generated. Since the light ray with the internal reflection angle φ1+φ2 has the same internal reflection angle as the light ray from the field angle θ1+θ2, the light ray with the internal reflection angle φ1+φ2 is visually recognized as a ghost image (i.e., an inverted image) that appears at a position where the field angle is inverted. Therefore, by making ψ≦φ1-φ2<φ1(=φ), it is possible to prevent the incident light ray from reaching the incident surface 110 after being reflected by the transmissive-reflective surface 120 and generating a ghost image.

[0021] The light guide member 310 according to the reference example shown in Fig. 5 includes an incident surface 110, a transmission reflection surface 120, and a reflection surface 130, and has a hollow structure. Incident light with an optical path width D is incident on the incident surface 110. The transmission reflection surface 120 reflects a part of the incident light at an internal reflection angle θ and transmits another part. The light that enters the inside of the light guide member 310 is reflected back and forth N times, and is emitted from the transmission reflection surface 120 to a display viewing zone S. The width of the display viewing zone S corresponds to the width of the light emitted from the transmission reflection surface 120. The wider the display viewing zone S, the wider the range of the outside scene that the user can view.

[0022] Since the internal reflection angle φ is equal to the incident angle θ, the light guide width T = D / (2 sin θ) and N+1 = S / D hold. Therefore, T = S / (2(N+1) sin θ). Therefore, by increasing the number of round trips of reflection N, the light guide width T can be reduced to make the device thinner.

[0023] However, increasing the number of round trips N increases the variation in luminance of the emitted light. Also, increasing the number of round trips N increases the number of boundaries of the optical path of the emitted light from the transmissive-reflective surface 120. As a result, discontinuity of the visual image in the display viewing zone S increases.

[0024] 6 has a solid structure in which the transmissive and reflective surfaces 120 and 130 are connected and integrated with each other using a transmissive member with a refractive index n. The internal reflection angle φ inside the light guide member 320 is larger than the incident angle θ. Therefore, T=S / (2(N+1)sinφ)

[0025] However, when the optical path inside the light-guiding member 320 is compressed by making the incident angle θ<the internal reflection angle φ, the first inclination angle ψ of the incident surface 110 cannot be increased. As a result, as shown in Fig. 7, a display gap occurs in the display viewing zone S, and the visual image becomes discontinuous. Therefore, in order to avoid discontinuity, it is necessary to make the first inclination angle ψ closer to the internal reflection angle φ.

[0026] ​ On the other hand, in order to reduce the thickness, it is necessary to increase the difference between the first angle α and the second angle β. That is, in order to reduce the thickness, it is necessary to increase the first angle α. α=π / 2-(θ+ψ), β=π / 2-(φ+ψ). In addition, in order to reduce the thickness, it is necessary to satisfy the condition θ<φ, and in order to satisfy the condition θ<φ, it is necessary to satisfy the condition α>0. Furthermore, since θ+α=φ+β=π / 2-ψ, when ψ and φ are approximately the same, it is necessary to satisfy the condition θ+ψ<φ+ψ<π / 2. That is, in order to reduce the thickness and avoid discontinuity of the visual image, θ<π / 4 must be satisfied. That is, for external light with an incident angle θ greater than π / 4, it is impossible to avoid discontinuity and reduce the thickness at the same time.

[0027] Therefore, in order to avoid discontinuity in the visual image while achieving a thin structure even when the incident angle θ exceeds π / 4, it is necessary to make the height Td greater than the light-guiding width T and make the second inclination angle ξ smaller than the internal reflection angle φ, while satisfying ψ<π / 4<φ. FIG. 8 shows a light guide member 340 configured so that the second inclination angle ξ is larger than the internal reflection angle φ. When ξ>φ, the uppermost light ray LA of the light L incident on the incident surface 110 does not pass through the end Pa. Therefore, a gap in the optical path occurs between the light ray LA and the light ray LB, and the visual image in the display viewing area S becomes discontinuous. The light ray LB is a light ray that enters from the incident surface 110, is reflected by the transmissive reflecting surface 120, and reaches the end Pa. The end Pa is the end of the reflecting surface 130 that is connected to the inclined surface 140. On the other hand, when ξ<φ, the light ray LA passes through the end Pa, so that no gap in the optical path occurs between the light ray LA and the light ray LB, and the continuity of the visual image in the display viewing area S is ensured.

[0028] Therefore, the predetermined conditions for realizing a thin structure, suppressing ghost images, and suppressing an increase in the number of repetitions and discontinuity of the visual image are (i) incident angle θ<internal reflection angle φ, (ii) first inclination angle ψ<internal reflection angle φ, (iii) height Td<light guide width T, and (iv) second inclination angle ξ<internal reflection angle φ. By adjusting the height Td within a range where Td>T for the desired incident angle θ, it is possible to realize an optical light guide member 101 that also satisfies the conditions (i), (ii), and (iv).

[0029] Moreover, the height Td is minimum when the light ray incident on the inclined surface 140 is parallel to the inclined surface 140. If the height Td is smaller than this, the incident light ray interferes with the inclined surface 140. That is, when the distance between the intersection point of the uppermost light ray LA and the lowermost light ray LB and the transmission-reflection surface 120 coincides with the light guide width T, the height Td is minimum, and this relationship is Td≧2T×tanφ / (tanφ+tanψ). If ψ<φ<π / 2, Td>T is always satisfied. Furthermore, the required value for the height of Td is maximum (i.e., the minimum required height) when the angle ψ of the incident portion is small and the inclination angle ξ of the inclined surface 140 is small. The condition for minimizing the inclination angle ξ is that the incident angle θ is 0. Only when the first inclination angle ψ is a positive value, a light ray with θ=0 can be incident, so the minimum value of the first inclination angle ψ is 0. When the first inclination angle ψ=0, the height Td of the incident portion is calculated as Td=2T from the above formula. Since it is desirable to make the height of the incident portion as small as possible in order to make the light guiding member thinner, the maximum value of Td that can accommodate a wide range of incident angles without wasting height is 2T.

[0030] Furthermore, when the incident angle θ of light L from outside falls within the range of θ1-θ2 to θ1+θ2, if the ray with the maximum incident angle θ1+θ2 does not pass through the end Pa, a gap will occur in the optical path and the visual image will become discontinuous. Therefore, as shown in Fig. 9, the internal reflection angle φ is set to the reflection angle when the incident angle θ is the maximum incident angle θ1+θ2 so that the ray with the maximum incident angle θ1+θ2 passes through the end Pa.

[0031] Furthermore, when the range of the incident angle θ is θ1-θ2 to θ1+θ2 and the range of the internal reflection angle φ is φ1-φ2 ​​to φ1+φ2, the light-guiding member 101 is configured to satisfy the condition ξ<φ1-φ2 ​​in order to ensure continuity of the visual image.

[0032] <1-2.Effects> According to the first embodiment described above in detail, the following effects are achieved. (1) Since the internal reflection angle φ is larger than the incident angle θ, the number of internal reflections is suppressed while the optical light-guiding member 101 can be thinned. Furthermore, since the first inclination angle ψ and the second inclination angle ξ are smaller than the internal reflection angle φ and the height Td is larger than the light-guiding width T, the continuity of the visual image in the display viewing zone S can be ensured. Furthermore, since the height Td is equal to or smaller than twice the light-guiding width T, the height of the incident portion can be limited to a certain value or less. Therefore, it is possible to avoid discontinuity in the visual image and an increase in the number of reflections, and to realize an optical light-guiding member that can be thinned.

[0033] (2) Since the emission section 21 is composed of a double structure of the transmissive-reflecting surface 210 and the prism array 211, a portion of the light L incident on the emission section 21 can be reflected and another portion can be emitted at the same angle as the incident angle θ.

[0034] (3) By providing the light absorbing member on the inclined portion 40, it is possible to suppress reflection of the light L that reaches the inclined portion 40 from inside the light guide member 101. As a result, it is possible to suppress the occurrence of ghost images in the display viewing zone S.

[0035] 2. Second Embodiment <2-1. Differences from the first embodiment> The second embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and the preceding description will be referred to.

[0036] The optical light guiding member 101 according to the first embodiment includes the emission portion 21. In contrast, as shown in Fig. 10, the optical light guiding member 102 according to the second embodiment differs from the first embodiment in that it includes an emission portion 22 instead of the emission portion 21.

[0037] 11 shows an enlarged view of a portion of the emission section 22. The emission section 22 is composed of a transmission type hologram. The emission section 22 converts the angle φ into an angle θ' by transmission diffraction. That is, the emission section 22 converts a light beam incident at an angle φ into a light beam at an angle θ'.

[0038] Here, by setting θ' so as to satisfy the condition sinθ'=sinθ / n, the light ray with angle θ' is emitted at angle θ from the emission unit 22. Therefore, the angle of the light L emitted from the emission unit 22 becomes equal to the incident angle θ of the light L to the light-guiding member 102.

[0039] Furthermore, by appropriately adjusting the diffraction efficiency of the hologram, the light can be split into a light diffracted by the hologram (i.e., a light ray with an angle θ') and a light ray LC that passes through the hologram and is reflected at the interface with air and guided in. Note that emission unit 22 may be any member having a diffraction function, and may be a diffractive optical member such as a diffraction grating other than a hologram.

[0040] <2-2.Effects> According to the second embodiment described above in detail, in addition to the effects (1) and (3) of the first embodiment described above, the following effect is also obtained.

[0041] (4) Since the emission section 22 is composed of a hologram, by appropriately adjusting the diffraction efficiency, it is possible to reflect a portion of the light L incident on the emission section 22 and emit another portion at the same angle as the incident angle θ.

[0042] 3. Third Embodiment <3-1. Differences from the first embodiment> The third embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configurations, and the preceding description will be referred to.

[0043] The light guiding member 101 according to the first embodiment includes the incident portion 10. In contrast, as shown in Fig. 12, the light guiding member 103 according to the third embodiment differs from the first embodiment in that it includes an incident portion 11 instead of the incident portion 10.

[0044] 13, the entrance portion 11 is configured with a prism array in which a plurality of prisms 111a are arranged. By configuring the entrance portion 11 with a prism array, the height Td can be made smaller than in the first and second embodiments by utilizing the steps of the prism array while maintaining the first inclination angle ψ.

[0045] Each prism 111a includes an incident side surface 111b and an incident facing surface 111c facing the incident side surface 111b. The incident side surface 111b is inclined at a first inclination angle ψ with respect to a first normal line l1. That is, the incident side surface 111b and the exit side surface 211b are parallel to each other. Light L from an outside scene is incident on the incident side surface 111b and exits from the exit side surface 211b. Since the incident side surface 111b and the exit side surface 211b are parallel to each other, chromatic dispersion of the light L at the time of incidence is offset at the time of emission.

[0046] A light absorbing film is disposed on the incident facing surface 111c. The incident facing surface 111c is parallel to the exit facing surface 211c. The incident facing surface 111c and the exit facing surface 211c are inclined at a predetermined angle with respect to the first normal line l1. This predetermined angle is close to the incident angle θ. The inclination angle δ of the third normal line l3 with respect to the first normal line l1 is equal to the inclination angle of the second normal line l2, and the relationship between the inclination angle δ and the first inclination angle ψ is δ+ψ=π / 2. As described above, in order to achieve a thin shape, the condition θ+ψ<φ+ψ<π / 2 is satisfied. Therefore, φ<δ is satisfied, and the inclination angle δ is larger than the internal reflection angle φ. The third normal line l3 is a normal line to the incident side surface 111b. This suppresses the optical path from being lost, and also suppresses the user from seeing the prism slope.

[0047] Incidentally, the incident portion 11 may be changed to a prism sheet in which a plurality of prisms 111a are arranged, or may be changed to another periodic structure. <3-2.Effects> According to the third embodiment described above in detail, in addition to the effects (1) and (3) of the first embodiment described above, the following effect is also obtained.

[0048] (5) Since the incident portion 11 is formed of a prism array, the height Td can be made smaller while maintaining the first inclination angle ξ, compared to when the incident portion 11 is a smooth surface. (6) Since the exit side surface 211b and the entrance side surface 111b are configured to be parallel to each other, the chromatic dispersion of the light L at the time of incidence can be offset at the time of emission.

[0049] (7) Since the incident surface 111c and the exit surface 211c are configured to be parallel to each other, the prism slope is prevented from being seen by the user. (4. Other embodiments) Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms.

[0050] (a) The light-guiding member 102 according to the second embodiment includes the incident portion 10, but instead of the incident portion 10, it may include an incident portion configured with a diffractive optical member such as a diffraction grating or a hologram.

[0051] (b) Multiple functions possessed by one component in the above embodiments may be realized by multiple components, or one function possessed by one component may be realized by multiple components. Also, multiple functions possessed by multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, part of the configuration of the above embodiments may be omitted. Also, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. [Explanation of symbols]

[0052] 10,11...Incidence part, 10a...First side, 10b...Second side, 21,22...Emission part, 30...Reflection part, 40...Slope part, 50...Terminal part, 60...Transparent member, 101,102,103...Light guide Members, 111a, 211a...Prism, 111b...Incidence side surface, 111c...Incidence opposing surface, 210...Transmission / reflection surface, 211...Prism array, 211b...Emission side surface, 211c...Emission opposing surface.

Claims

1. An incident portion (10, 11) having a first side (10a) and a second side (10b) opposite to the first side and configured to receive external light from an external scene; an emission section (21, 22) that is in contact with the first side so as to be inclined with respect to the incidence section and is configured to transmit a part of the incident external light and reflect another part of the incident external light; A reflecting section (30) arranged parallel to the emitting section and spaced apart from the emitting section and configured to reflect the incident external light; a sloped portion (40) connecting the second side and a side of the reflecting portion on the incident side, The internal reflection angle (φ) inside the reflecting portion and the emitting portion is an angle with a first normal (l1) of the emitting portion as a reference line in the light guiding cross section, and is configured to be larger than the incident angle (θ) of the external light in the light guiding cross section, and the light guiding cross section corresponds to a plane defined by the first normal and a second normal (l2) of the incident portion, a first inclination angle (ψ) of the incident portion is an angle based on the first normal line at the light guiding cross section, and is configured to be smaller than the internal reflection angle; A height (Td) from the emission portion to the second side in the direction of the first normal is configured to be larger than a distance (T) between the emission portion and the reflection portion, A second inclination angle (ξ), which is an inclination angle of the inclined portion, is an angle based on the first normal line at the light guiding cross section, and is configured to be equal to or smaller than the internal reflection angle. Light guide member.

2. The height is configured to be equal to or less than twice the interval. The light guide member according to claim 1 .

3. the sum of the first tilt angle (ψ) and the internal reflection angle (φ) is less than π / 2; The light guide member according to claim 1 .

4. The emission portion (22) is configured by a first periodic structure. The light guide member according to any one of claims 1 to 3.

5. The incident portion (11) is composed of the first periodic structure. The light guide member according to claim 4 .

6. The first periodic structure includes a diffraction grating or a hologram. The light guide member according to claim 4 or 5.

7. The emission section (21) is configured with a double structure of a reflection / transmission section (210) and a second periodic structure (211). The light guide member according to any one of claims 1 to 3.

8. The incident portion (11) is composed of the second periodic structure. The light guide member according to claim 7 .

9. The second periodic structure includes a prism array or a prism sheet in which a plurality of prisms (211a) are arranged along the light guiding cross section. The light guide member according to claim 8 .

10. Each prism of the emission section includes an emission side surface (211b) configured to emit the external light, and an emission opposing surface (211c) opposing the emission side surface, Each prism of the incident portion includes an incident side surface (111b) configured to receive the external light, and an incident opposing surface (111c) opposing the incident side surface, The exit side surface is configured to be parallel to the entrance side surface. The light guide member according to claim 9 .

11. The exit surface is configured to be parallel to the entrance surface. The light guide member according to claim 10.

12. The internal reflection angle is the total reflection angle. The light guide member according to any one of claims 1 to 11.

13. The inclined portion has a light absorbing member. The light guide member according to any one of claims 1 to 12.

Images