Optical components

Abstract

To provide an optical member which is thinned while securing the visibility of the outside view and the area of a display visual area.SOLUTION: The optical member includes a light guide body 2 having an entrance surface 2a for receiving entrance of outside view light, an emission surface 2b for reflecting incident light having entered from the entrance surface 2a and emitting the incident light to the outside, and a reflection surface 2c facing the emission surface 2b and reflecting the reflected light from the emission surface 2b to the emission surface 2b. The emission surface 2b has a plurality of prism parts 3 formed of a plurality of inclined surfaces 31 to 33 with different inclinations. The reflection surface 2c has a reflection part 41 inclined by the same degree as one of the inclined surfaces 31 to 33.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an optical member that reflects part of the incident light inside and emits the incident light and its reflected light to the outside from a surface different from the incident surface.

Background Art

[0002] Conventionally, examples of this type of optical member include those described in Patent Document 1. The optical member described in Patent Document 1 includes a light guide having an incident surface on which external light is incident, a first surface to which the external light incident from the incident surface first travels, and a second surface facing the first surface, and a semi-transmissive mirror disposed on the first surface side. In this optical member, part of the external light incident from the incident surface is reflected by the semi-transmissive mirror to the second surface, the remainder is absorbed or transmitted by the semi-transmissive mirror, and the light reflected by the semi-transmissive mirror on the second surface is reflected to the second surface side. Then, in this optical member, a prism sheet having a plurality of prisms is disposed on the first surface, and the light transmitted through the semi-transmissive mirror is configured to be emitted to the outside through the plurality of prisms.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, this type of optical member is required to be thinned while ensuring a wide display area (hereinafter referred to as "display viewing area") for allowing a user to view a scene behind the optical member on the side of the exit surface where a plurality of prisms are arranged. The distance between the first surface and the second surface arranged in parallel among the optical members, that is, the thickness, is determined by the incident angle of external light on the first surface and the second surface, the width of the display viewing area, and the number of reciprocations. And, in order to thin the optical member while ensuring a wide display viewing area, it is necessary to increase the number of times (hereinafter referred to as "number of reciprocations") that the incident external light reciprocates between the first surface and the second surface.

[0005] However, when the number of reciprocations is increased, the boundaries between the external lights incident on the first surface, that is, the boundaries between the external lights with different numbers of reciprocations and adjacent to each other increase, and the continuity of the external scene in the display viewing area may be impaired. Further, when the first surface of the optical member is constituted by a semi-transmissive mirror, the luminance of the external light guided decreases as the number of reciprocations increases, so that the luminance change in the display viewing area becomes large. Thus, when simply thinning the optical member and increasing the number of reciprocations of the incident external light, it is difficult to ensure the visibility in the display viewing area.

[0006] In view of the above points, an object of the present invention is to provide an optical member that is thinned, has a wide display viewing area, and can ensure the visibility of the external scene in the display viewing area.

Means for Solving the Problems

[0007] To achieve the above object, the optical member according to claim 1 is an optical member that reflects external light inside and guides it, and includes a light guide body (2) having an incident surface (2a) on which external light is incident, an exit surface (2b) where the incident light incident from the incident surface first arrives and reflects the incident light and emits it to the outside, and a reflecting surface (2c) that is disposed opposite to the exit surface and reflects the reflected light reflected by the exit surface toward the exit surface. The exit surface has an inclination corner that is different Along with, it is inclined with respect to the reference plane of the injection surface.It has multiple prism sections (3) composed of multiple inclined surfaces (31, 32, 33), and the reflective surface has the same inclination as one of the multiple inclined surfaces. corner It has the same inclined surface (41) which is the surface that was designated as such.

[0008] This optical component comprises a light guide having an incident surface, an exit surface, and a reflecting surface, with the exit surface having multiple prism sections composed of multiple inclined surfaces. The reflecting surface has the same inclination as one of the inclined surfaces of the prism section. As a result, the angle of light that enters the light guide from the incident surface, is reflected by the exit surface and heads toward the reflecting surface, is greater than the angle of light that heads toward the exit surface inside the light guide. Consequently, even if the distance between the reflecting surface and the exit surface, i.e., the thickness, is reduced, the width of one round trip between the reflecting surface and the exit surface of the incident light is increased, and a wider display field of view can be secured. Furthermore, since the width of one round trip between the reflecting surface and the exit surface of the incident light is secured to a predetermined level or more, even if the thickness is reduced, it is not necessary to excessively increase the number of round trips inside the light guide. Therefore, this optical component can be made thinner, widening the display field of view while ensuring the visibility of the surrounding scenery within the display field of view.

[0009] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view showing an optical component of the first embodiment. [Figure 2] This is an explanatory diagram of the light guide in the optical member of the first embodiment. [Figure 3] This is an enlarged cross-sectional view showing region III in Figure 1. [Figure 4] This is a schematic diagram showing the relationship between the inclination angle of each inclined surface constituting the prism section of the emission surface and the light guide. [Figure 5] This is an explanatory diagram showing the tilt angle of the back and the resulting suppression of gaps in the light guide. [Figure 6]This is a schematic diagram showing the optical components and light guide of a comparative example. [Figure 7] This is a cross-sectional view showing an optical component of the second embodiment. [Figure 8] This is a schematic diagram showing the prism portion and width of the first to third regions of the injection surface in the second embodiment. [Figure 9] This is an explanatory diagram of the light guide in the optical member of the second embodiment. [Figure 10] This is a cross-sectional view showing a first modified example of the optical member of the second embodiment. [Figure 11] This is a cross-sectional view showing a second modified example of the optical member of the second embodiment. [Figure 12] Figure 11 is an explanatory diagram of the light guide in the optical component. [Figure 13] This is an explanatory diagram illustrating the gap in light rays caused by a reflective surface having a prism section. [Figure 14] This is a cross-sectional view showing a third modified example of the optical member of the second embodiment. [Figure 15] This is an enlarged cross-sectional view showing region XV in Figure 14. [Figure 16] This figure corresponds to Figure 15 and is an enlarged cross-sectional view showing the cavity layer formation process. [Figure 17] This is a diagram corresponding to Figure 15, and is an enlarged cross-sectional view showing a modified example in which a reflective layer is present instead of a cavity layer. [Figure 18] This is a cross-sectional view showing an optical component of another embodiment. [Modes for carrying out the invention]

[0011] The embodiments of the present invention will be described below 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.

[0012] (First Embodiment) The optical element 1 of the first embodiment will be described with reference to the drawings. The optical element 1 of this embodiment can be used as a blind spot assisting device, which is attached to, for example, a member or obstacle that obstructs the user's field of view and creates a blind spot, and allows the user to see the scenery in the blind spot area. For example, in the case of an in-vehicle application, the optical element 1 is attached to the pillar of the vehicle on which it is mounted, and guides ambient light from the area that becomes a blind spot due to the pillar towards the user, allowing the user to see the scenery in the blind spot area.

[0013] In Figure 4, hatching is applied to the light incident on optical element 1 and the light emitted from optical element 1 to the outside, in order to make the light guidance within optical element 1 easier to understand.

[0014] The optical component 1 includes a light guide 2 made of a light-transmitting material, as shown in Figure 1, for example. The light guide 2 includes an incident surface 2a into which light from the outside is incident, an exit surface 2b adjacent to the incident surface 2a, a reflecting surface 2c facing the exit surface 2b, an end surface 2d connecting the exit surface 2b and the reflecting surface 2c, and a back surface 2e connecting the incident surface 2a and the reflecting surface 2c. The optical component 1 causes light from the outside to be incident into the interior of the light guide 2 from the incident surface 2a, and while a portion of the incident light is repeatedly reflected between the exit surface 2b and the reflecting surface 2c, a portion of the light is emitted to the outside from the exit surface 2b. As a result, the optical component 1 allows a user on the side of the exit surface 2b to see the scenery in a blind spot area.

[0015] For the sake of explanation, as shown in Figure 2, for example, the light incident on the light guide 2 from the outside will be referred to as "external light L1," and the light from the external light L1 that enters the interior of the light guide 2 from the incident surface 2a will be referred to as "incident light." The light from the incident light that directly enters the exit surface 2b from the incident surface 2a will be referred to as "first incident light L 21 The reflected light that is part of the incident light that is reflected by the exit surface 2b and heads toward the reflection surface 2c is called the "second incident light L 22 It is called ". Also, the second incident light L 22 The light reflected by the reflective surface 2c and directed toward the emission surface 2b is called the "third incident light L 23The light emitted to the outside from a portion of the emission surface 2b is called "emission light L3," and the light that passes to the outside from the end surface 2d is called "afterglow L4."

[0016] 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 incident light is totally reflected by the first inclined surface 31 and the reflective surface 2c of the exit surface 2b, as shown in Figure 2, and guided inside. The details of this will be described later. The light guide 2 is configured such that the maximum thickness Td of the incident surface 2a is greater than the thickness Ts of the part where the exit surface 2b and the reflective surface 2c face each other. In other words, if the direction in which incident light travels while being reflected by the exit surface 2b and the reflective surface 2c is called the "light guiding direction D1", the light guide 2 is configured such that the thickness of the part where the exit surface 2b and the reflective surface 2c face each other in the light guiding direction D1 is thinner than the thickness of other parts. The light guiding direction D1 can also be said to be the direction from the end of the exit surface 2b on the incident surface 2a side to the end on the end surface 2d side. The maximum thickness Td can also be said to be the height of the incident surface.

[0017] The incident surface 2a is the surface that directs ambient light L1 into the interior of the light guide 2. The direction connecting the emission surface 2b and the reflection surface 2c is defined as the "thickness direction D2," and the incident surface 2a is inclined with respect to the thickness direction D2 at an angle ψ (<90°). The incident surface 2a, with an inclination angle ψ, receives the first incident light L1. 21 It is smaller than the light guide angle φ. The light guide angle φ is the first incident light L 21 This refers to the angle between the direction of propagation (incident direction) and the thickness direction D2. If the angle between the direction of propagation of the ambient light L1 incident on the incident surface 2a and the thickness direction D2 is defined as the "incident angle θ", then, according to the refraction condition, if ψ < π / 2 - φ, then the first incident light L 21 The light is refracted in a direction where φ is greater than the incident angle θ of the ambient light L1. That is, if ψ < π / 2 - φ is satisfied, the first incident light L 21 The light is guided to a wider area of ​​the emission surface 2b.

[0018] The emission surface 2b is composed of a plurality of first prism parts 3 configured to have a first inclined surface 31, a second inclined surface 32, and a third inclined surface 33 with different inclination angles respectively, as shown in FIG. 3 for example. Here, "inclined surface" refers to a surface that is inclined with respect to the "reference surface of the injection surface 2b," where the virtual plane obtained by flattening the entire injection surface 2b is considered the "reference surface of the injection surface 2b." The emission surface 2b is a prism array in which a plurality of first prism parts 3 are repeatedly arranged along the light guiding direction D1. The first prism part 3 is configured such that, for example, the first inclined surface 31, the second inclined surface 32, and the third inclined surface 33 are arranged in this order along the light guiding direction D1.

[0019] The first inclined surface 31, as shown in FIGS. 2 and 3 for example, is a surface that reflects the first incident light L 21 and the third incident light L 23 by total reflection and functions as a mirror. The first inclined surface 31 is inclined at an angle α1 with respect to the thickness direction D2, as shown in FIG. 4 for example. Specifically, the first inclined surface 31 is such that the angle α1 is greater than the light guiding angle φ and less than 90°. The first inclined surface 31 is inclined such that the angle formed by the advancing direction of the first incident light L 21 and the third incident light L 23 and the normal direction to the first inclined surface 31 is greater than the light guiding angle φ. Thereby, the first incident light L 21 and the third incident light L 23 are incident on the first inclined surface 满足φ < α1 and are reflected by the first inclined surface 满足α1 < π / 2 so that the angle with respect to the thickness direction D2 becomes ε greater than the light guiding angle φ. [[ID=​​​​​​​​​​​​​​23 It becomes possible to reflect the light.

[0022] The second inclined surface 32 is adjacent to the first inclined surface 31 and is inclined at an angle β1 different from α1 with respect to the thickness direction D2. The second inclined surface 32 receives the first incident light L 21 and the third incident light L 23 The inclination angle β1 is smaller than the light guide angle φ so that the first incident light L does not directly enter and cause unintended reflection. 21 and the third incident light L 23 Of the light that does not reach the first inclined surface 31, it is incident on the third inclined surface 33 without being blocked by the second inclined surface 32. The second inclined surface 32 may be covered with a light-absorbing film (not shown) to suppress the generation of ghost images caused by the intrusion of unintended ambient light.

[0023] The third inclined surface 33 receives the first incident light L, as shown in Figures 2 and 4, for example. 21 and the third incident light L 23 This is the surface from which the light is emitted to the outside as emitted light L3. The third inclined surface 33 is inclined at an angle γ that is different from α1 and β1 with respect to the thickness direction D2, as shown in Figure 4, for example. Preferably, the third inclined surface 33 has an inclination where γ is equal to ψ, that is, it is parallel to the incident surface 2a. As a result, the emitted light L3 is emitted at the same angle as the ambient light L1, the discrepancy between the scene caused by ambient light L1 and the scene caused by emitted light L3 is suppressed, and visibility at the emission surface 2b is improved.

[0024] In this embodiment, the reflective surface 2c has a plurality of second prism sections 4, each consisting of a reflective section 41 and an adjacent surface 42 adjacent to it. The reflective surface 2c is a prism array in which the plurality of second prism sections 4 are repeatedly arranged along the light guide direction D1.

[0025] The reflective portion 41, as shown in Figure 2, for example, reflects the second incident light L 22It is a surface that reflects light by total internal reflection and functions as a mirror. The reflective portion 41 is inclined at an angle α1 with respect to the thickness direction D2, as shown in Figure 3, for example, and is the same inclined surface as the first inclined surface 31. In other words, the reflective portion 41 is parallel to the first inclined surface 31. As a result, the second incident light L on the reflective portion 41 22 The angle of incidence becomes δ, and since equation (1) above is satisfied, the reflecting section 41 is designed to produce total internal reflection of the incident light, similar to the first inclined surface 31. The third incident light L reflected by the reflecting section 41 23 The first incident light L 21 Similarly, the light rays will become ray rays with a light guide angle φ and head towards the emission surface 2b.

[0026] The adjacent surface 42 is a surface adjacent to the reflective portion 41 and is inclined at a different angle with respect to the thickness direction D2 than the reflective portion 41. The adjacent surface 42 is, for example, a surface adjacent to the second incident light L 22 The inclination angle with respect to the thickness direction D2 is adjusted as appropriate to prevent direct incidence of the light.

[0027] The terminal surface 2d is the surface connecting the emission surface 2b and the reflection surface 2c, and is, for example, an inclined surface tilted at a predetermined angle. At the terminal surface 2d, a portion of the incident light L2 that was repeatedly reflected by the first inclined surface 31 and the reflection section 41 and did not reach the third inclined surface 33 is emitted to the outside as afterglow L4.

[0028] The end surface 2d may be subjected to light-shielding treatment, such as by placing a light-absorbing film (not shown). This can suppress the generation of ghosting due to leakage of afterglow L4. The end surface 2d may also have a configuration that is continuous with the third inclined surface 33 of the end of the multiple first prism sections 3 that is located on the opposite end from the incident surface 2a, that is, it may have the same inclination as the third inclined surface 33. In this case, the afterglow L4 from the end surface 2d also becomes emitted light L3, and the loss of light rays can be suppressed.

[0029] The back surface 2e is an inclined surface that linearly connects the end 2a1 of the incident surface 2a opposite to the exit surface 2b and the end 2c1 of the reflective surface 2c opposite to the end surface 2d, as shown in Figure 2, for example. The back surface 2e is inclined at an angle ξ with respect to the thickness direction D2 that is smaller than the light guide angle φ. As a result, as shown in Figure 5, the first incident light L 21 A portion of it passes near the end 2c1, and the second incident light L 22 A portion of it will be incident on the reflective portion 41 near the end 2c1. In other words, the first incident light L passing through the vicinity 21 The third incident light L reflected by the reflective portion 41 near the end 2c1 23 Since the gap between the two (i.e., the light guide gap) is suppressed, the visibility of the scene that the user sees on the emission surface 2b is improved.

[0030] The above describes the basic configuration of the optical element 1 of this embodiment. With the above configuration, the optical element 1 can guide incident light by total internal reflection without the need for a semi-transparent mirror or mirror made of a different material from the light guide 2. Furthermore, the optical element 1 can ensure a wide viewing area S on the ejection surface 2b while making the thickness Ts of the portion where the ejection surface 2b and the reflective surface 2c face each other thinner than in conventional designs.

[0031] In this context, the display area S refers to the maximum width between the emitted light beams L3 at both ends in the light guide direction D1 of the emission surface 2b, as shown in Figure 2, for example.

[0032] Next, the thickness Ts of the optical element 1 will be explained in comparison with the comparative example optical element 100 shown in Figure 6.

[0033] The comparative optical member 100, like optical member 1, has a light-transmitting light guide 101 and is configured to guide ambient light L1 by total internal reflection without having a semi-transparent mirror or mirror made of other materials. The optical member 100 has an incident surface 101a, an exit surface 101b, a reflecting surface 101c, and an end surface 101d, and the thickness T of the portion of the exit surface 101b that is the light-reflecting part, the flat portion 103, and the portion facing the reflecting surface 101c are uniform. In other words, the optical member 100 has multiple flat portions 103 and reflecting surfaces 101c that are parallel to each other. The exit surface 101b is made up of a repeating arrangement of a prism portion 102 that emits incident light to the outside and a flat portion 103 that reflects incident light by total internal reflection. The prism section 102 has an emission section 102a that emits incident light to the outside, and an adjacent surface 102b adjacent to the flat section 103 on the incident surface 101a side. The optical member 100 receives the first incident light L 21 The light is reflected at the flat section 103 at a light guide angle φ, and the second incident light L 22 As a result, the second incident light L 22 The light is incident on the reflective surface 101c at a light guide angle φ and is reflected to the emission surface 101b by total internal reflection.

[0034] In the comparative example optical member 100, the direction normal to the flat portion 103 and the reflective surface 101c is the thickness direction D2.

[0035] Here, in order to ensure a wide viewing area in the optical element 100, the width in the light guiding direction D1 when the incident light makes one round trip between the flat portion 103 and the reflective surface 101c is defined as the "round trip width W," and it is necessary to ensure that the round trip width W is greater than or equal to a predetermined value. In order to widen the round trip width W, it is necessary to increase the thickness T of the optical element 100. The round trip width W in the optical element 100 is expressed by the following equation (3).

[0036] W = 2 × T × tanφ (3) In other words, in order to ensure a display viewing area greater than a predetermined value, the optical element 100 needs to either make the light guide angle φ as large as possible with respect to the incident angle θ, or make its thickness T greater than a predetermined value. However, the latter method goes against the need for miniaturization, so the former method is preferable to achieve both a display viewing area and miniaturization.

[0037] Here, let α2 be the angle between the normal direction to the incident surface 101a and the direction in which the background light L1 travels, and the angle between this normal direction and the first incident light L 21 Let β2 be the angle with respect to the direction of propagation, and let n0 be the refractive index of the light guide 101. The light guide angle φ satisfies equation (4) below. Also, when ψ is the inclination angle of the incident surface 101a with respect to the thickness direction D2, equations (5) and (6) below hold.

[0038] sinβ² = sinα² / n₀···(4) α² = π / 2 - θ - ψ···(5) β² = π / 2 - φ - ψ···(6) According to equations (4) through (6), in order to make the light guide angle φ as large as possible compared to the incident angle θ, it is necessary to increase α2. However, increasing α2 increases the proportion of reflection of ambient light L1 at the incident surface 101a, as well as the proportion of reflection of incident light at the exit portion of the prism section 102 parallel to the incident surface 101a, so there is a concern about the loss of light rays due to reflection.

[0039] Therefore, the optical component 100 has limitations in reducing its thickness T while ensuring a display viewing area greater than a predetermined size, making it difficult to achieve both securing a display viewing area and reducing the thickness.

[0040] On the other hand, the reciprocating width W in the optical element 1 is expressed by the following equation (7).

[0041] W=Ts×tanε+Ts×tanφ=Ts(tanε+tanφ)···(7) When the reciprocating width W of the optical member 1 and the optical member 100 of the comparative example is the same, according to equations (3) and (7), equation (8) holds between the thickness Ts of the optical member 1 and the thickness T of the optical member 100.

[0042] Ts = 2×T×tanφ / (tanε + tanφ) ··· (8) Since the optical member 1 is designed such that φ < ε < π / 2, tanε > tanφ, and tanφ / (tanε + tanφ) is less than 1 / 2, that is, Ts < T. That is, the optical member 1 has a thinner configuration while securing the same display viewing area as the optical member 100. Further, unlike the optical member 100, the optical member 1 does not need to increase α2 above a predetermined value, so an effect of suppressing light loss due to reflection on the incident surface 2a and the third inclined surface 33 is also obtained.

[0043] According to the present embodiment, the external scene light L1 incident on the incident surface 2a at an incident angle θ becomes the first incident light L with a light guiding angle φ larger than θ. 21 And the first incident light L 21 is incident on the reflection portion 41 as the second incident light L with a light guiding angle ε larger than φ on the first inclined surface 31. 22 Thus, the optical member 1 can secure the reciprocating width W required for the incident light to make a round trip between the emission surface 2b and the reflection surface 2c while reducing the thickness Ts of the portion where the emission surface 2b and the reflection surface 2c face each other. Therefore, it is possible to achieve both securing the display viewing area and thinning. Further, since it does not have a semi-transmissive mirror or a mirror made of a material different from the light guide 2 and guides the incident light by total reflection, light loss due to light absorption in the light guide 2 is suppressed, and the visibility of the external scene on the emission surface 2b is improved compared to the conventional case.

[0044] (Second Embodiment) The optical member 1 of the second embodiment will be described with reference to the drawings.

[0045] The optical member 1 of the present embodiment is different from the first embodiment in that the configuration of the emission surface 2b is changed, for example, as shown in FIG. 7. In the present embodiment, this difference will be mainly described.

[0046] In this embodiment, the ejection surface 2b is composed of, for example, a first region 2ba, a second region 2bb, and a third region 2bc, extending from the incident surface 2a towards the end surface 2d. The first region 2ba and the second region 2bb are prism arrays in which a plurality of first prism sections 3 are repeatedly arranged, but the ratio of the width of the first inclined surface 31 to the width of the second inclined surface 32 to the third inclined surface 33 is different. The third region 2bc is a prism array in which a plurality of prism sections are repeatedly arranged, having the second inclined surface 32 and the third inclined surface 33, but not the first inclined surface 31.

[0047] For the sake of explanation, as shown in Figure 8, for example, the widths of the first inclined surface 31 in the light guide direction D1 for the first region 2ba and the second region 2bb will be Pa1 and Pa2, respectively. Also, for the first region 2ba to the third region 2bc, the widths of the second inclined surface 32 to the third inclined surface 33 in the light guide direction D1 will be Pb1, Pb2, and Pb3, respectively.

[0048] In Figure 8, a hypothetical straight line connecting both ends of the first prism section 3 and the extension of the second inclined surface 32 are shown as dashed lines, and the intersection point P between the hypothetical straight line and the extension is also shown. The hypothetical straight line in Figure 8 is parallel to the light guide direction D1. Widths Pa1 and Pa2 are the widths from the end of the first inclined surface 31 to the intersection point P, and widths Pb1 and Pb2 are the widths from the intersection point P to the end of the third inclined surface 33. In other words, widths Pa1 and Pa2 are the first widths that contribute to reflection, i.e., the reflection widths. Widths Pb1, Pb2, and Pb3 are the second widths that contribute to emission, i.e., the emission widths. Hereinafter, the ratio of the width of the first inclined surface 31 (reflection width) to the sum of the reflection width and emission width in the first prism section 3 is referred to as the "reflection width ratio".

[0049] The first region 2ba and the second region 2bb are configured such that Pa1 / Pb1 > Pa2 / Pb2. In other words, the first region 2ba is a prism array with a higher ratio of the first inclined surface 31 that functions as a mirror compared to the second region 2bb. That is, the optical element 1 of this embodiment is configured such that the ratio of the first inclined surface 31 in the prism array increases in the order of the third region 2bc, the second region 2bb, and the first region 2ba. As a result, the amount of emitted light L3 in each region 2ba to 2bc is made approximately uniform, and the brightness in the display viewing area becomes approximately constant.

[0050] As in the first embodiment, if the ratio of the width of the first inclined surface 31 to the width of the second inclined surface 32 to the third inclined surface 33 is the same across the entire area of ​​the ejection surface 2b, then the ratio of the reflection width in the first prism section 3, i.e., the reflectance R, becomes constant. In other words, the amount of incident light L2 decreases at a constant rate as the number of reflections by light guidance increases. For example, if the reflectance R = 0.6 and the first incident light L 21 When the light intensity of the first reflected light at the emission surface 2b is set to 100%, the light intensity of the first reflected light at the emission surface 2b is 100 × 0.6 = 60%, and the light intensity of the remaining emitted light L3 is 100 - 60 = 40%. Next, the light intensity of the second reflected light at the emission surface 2b is 60 × 0.6 = 36%, and the light intensity of the remaining emitted light L3 is 60 - 36 = 24%. Then, the light intensity of the third reflected light at the emission surface 2b is 36 × 0.6 = 21.6%, and the light intensity of the remaining emitted light L3 is 36 - 21.6 = 14.4%. In this way, when the ratio of the reflection width at the emission surface 2b is constant, the light intensity of the emitted light L3 decreases with each reflection, such as 40% for the first emitted light L3, 24% for the second emitted light L3, and 14.4% for the third emitted light L3. Therefore, the further away from the incident surface 2a is in the display viewing area, the darker it appears to the user.

[0051] In contrast, in this embodiment, the injection surface 2b is composed of multiple regions with different ratios of reflection width, and the reflectance R is different for each region. For example, suppose the injection surface 2b is configured such that the reflectance R of the first region 2ba is 2 / 3, the reflectance R of the second region 2bb is 1 / 2, and the reflectance R of the third region 2bc is 0.

[0052] As shown in Figure 9, for example, the emitted light L3 that is emitted from the first region 2ba is called "first emitted light L 31 "The thing emitted from the second region 2bb is called "second emitted light L 32 "The thing emitted from the third region 2bc is called "Third Emitted Light L 33 They are referred to as "[...]" respectively.

[0053] In this case, the first incident light L 21 When the light intensity of is set to 100%, the amount of reflected light in the first region 2ba is 100 × 2 / 3 ≈ 67%, and the first emitted light L 31 The light intensity is 100 - 67 ≈ 33%. Also, the light intensity of the reflected light in the second region 2bb is 67 × 1 / 2 ≈ 34%, and the second emitted light L 32 The light intensity becomes 67-34≈33%, and in the third region 2bc, the third incident light L 23 Since all of it will be emitted, the third emitted light L 33 The amount of light is approximately 33%. In this way, by configuring the emission surface 2b with multiple regions having different ratios of reflection width, i.e., reflectance R, the emitted light L 31 ~L 33 The light intensity can be averaged to be roughly the same, reducing brightness unevenness in the display area.

[0054] In the above explanation, the case where the injection surface 2b is composed of three regions 2ba to 2bc was used as a representative example, but it is not limited to this. The injection surface 2b can be composed of multiple regions, such as two regions or four or more regions.

[0055] For example, if the maximum number of reflections of incident light L2 at the reflective surface 2c is m times (m: a natural number greater than or equal to 1), then the exit surface 2b is composed of m+1 regions. In this case, starting from the incident surface 2a, the regions are designated as the 1st region, the 2nd region, ... the (m+1)th region, and the ratio of the reflection widths decreases from the 1st region to the (m+1)th region, becoming zero in the (m+1)th region. For example, if the exit surface 2b is composed of four regions, the reflectance R in each region should be 3 / 4 in the 1st region, 2 / 3 in the 2nd region, 1 / 2 in the 3rd region, and 0 in the 4th region. Then, in the case of the four divided emission surface 2b, 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. Thus, when the emission surface 2b is composed of m+1 regions, the P of the x-th region is... ax / (P ax +P bx ) to P ax / (P ax +P bx The relationship is expressed as ) = (m+1-x) / (m+2-x), which ensures that the amount of emitted light L3 is uniform in each region. Note that x is an integer between 1 and m, and the reflectance in the m+1 region is 0.

[0056] Furthermore, in the first to (m+1)th regions, with reflection widths Pa1 to Pa(m+1) and emission widths Pb1 to Pb(m+1), the optical element 1 satisfies the following equation (9).

[0057] Pa1 / Pb1>Pa2 / Pb2>…>Pam / Pbm>Pa(m+1) / Pb(m+1)...(9) Furthermore, the multiple first prism sections 3 are composed of inclined surfaces of the same angle, except for the region closest to the terminal surface 2d that does not have the first inclined surface 31, and the width and height may be the same or different in each region. In addition, in the first to mth regions, the reflection widths Pa1 to Pam and the emission widths Pb1 to Pbm are preferably within a predetermined range centered on a constant value expressed by the following formulas 10 to 13, where k1 to km is the number of prism sections 3 in each region.

[0058]

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[0059]

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[0060]

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[0061]

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[0062] According to this embodiment, in addition to the same effects as the first embodiment described above, the optical member 1 is obtained in which the amount of light emitted from the emission surface 2b is averaged, thereby ensuring brightness. Furthermore, when the reflection width and emission width in each region of the emission surface 2b are within a predetermined range centered on a certain value, the effect of suppressing the occurrence of moiré patterns is also obtained.

[0063] (First modified example of the second embodiment) The optical element 1 may be configured such that, as shown in Figure 10, for example, the width Lc of the reflective portion 41 in the light guide direction D1 is partially or entirely different in the second prism portion 4 depending on the location. In other words, the optical element 1 may be a random surface, so to speak, in which the value of Lc on the reflective surface 2c is random. As a result, the second incident light L on the reflective surface 2c 22 The reflection pattern is no longer constant and periodic, and the third incident light L into the second region 2bb and the third region 2bc 23 The incidence pattern becomes random, which can suppress the occurrence of moiré patterns.

[0064] This modified version also provides the same effects as the second embodiment described above, as well as an optical component 1 that suppresses the occurrence of moiré patterns. In this modified version, even if the reflection width and the injection width are constant in each region of the injection surface 2b, the occurrence of moiré patterns can be suppressed because the reflection surface 2c is a random surface.

[0065] (Second modified example of the second embodiment) The optical element 1 may have a configuration in which the reflective surface 2c is a single flat surface 2ca, as shown in Figure 11, for example. In this case, the first prism portion 3 at the exit surface 2b is configured such that the first inclined surface 31 is parallel to the flat surface 2ca. As a result, the optical element 1, as shown in Figure 12, receives reflected light from the first region 2ba and the second region 2bb, i.e., the second incident light L 22 The light is reflected by the flat surface 2ca and directed toward the exit surface 2b. In addition, as a result, the optical element 1 receives the third incident light L 23 The gaps between them are suppressed.

[0066] Specifically, for example, as shown in Figure 13, if the reflective surface 2c has a configuration in which multiple second prism sections 4 are present, the second incident light L 22 There are edge portions that do not contribute to the reflection. Therefore, the third incident light L is generated by being reflected by different reflecting parts 41. 23 A gap in the light rays is created between them.

[0067] On the other hand, in this modified example, since the reflective surface 2c is a uniform flat surface 2ca, the gaps in the light rays, i.e., the periodic reflection pattern caused by the prism array of the reflective surface 2c, do not occur, and thus the occurrence of moiré can be suppressed. In addition, in this modified example, the second incident light L is directed to the reflective surface 2c. 22 Since there are no edge portions that do not contribute to reflection, there is no scattering of light at the edge portions, and this scattered light becomes the third incident light L 23 It does not superimpose. Therefore, unintended scattered light does not superimpose on the emitted light L3, resulting in an improved visibility of the surrounding scenery within the display area.

[0068] This modified version also provides the same effects as the second embodiment described above, as well as an optical member 1 that suppresses the occurrence of moiré patterns and improves the visibility of the surrounding scenery in the display area.

[0069] (Third modified example of the second embodiment) The optical element 1 may have a cavity layer 5 near the injection surface 2b, for example, as shown in Figure 14.

[0070] The cavity layer 5 is, for example, a plate-shaped space containing air. The cavity layer 5 is located in a region of the emission surface 2b that is composed of multiple first prism sections 3 having a first inclined surface 31, such as the first region 2ba and the second region 2bb. In other words, the cavity layer 5 is located in a region of the emission surface 2b other than the region that does not reflect incident light. With the reflective section 41 of the reflective surface 2c as the first reflective surface, the surface of the cavity layer 5 located on the opposite side of the first inclined surface 31, as shown in Figure 15, for example, is the second reflective surface 5a that reflects incident light. The width of the cavity layer 5 in the light guide direction D1 is appropriately changed in each region to match the width of the adjacent first inclined surface 31, so as not to obstruct the incidence of light to the third inclined surface 33.

[0071] The second reflective surface 5a has the same inclination as the reflective portion 41 (first reflective surface), that is, it is parallel to the reflective portion 41. The second reflective surface 5a is formed, for example, by the presence of air with a lower refractive index than the light guide 2 in the cavity layer 5, thereby reflecting the first incident light L 21 or third incident light L 23This surface is subject to total internal reflection.

[0072] In this modified example, a light-absorbing film 6 is formed on the outer surface of the first inclined surface 31. The light-absorbing film 6 is made of any material that absorbs visible light, such as black paint, and is formed by any method such as spray coating. This makes it possible to suppress unwanted ambient light from entering the light guide 2 from the exit surface 2b side, and the generation of noise and ghost images caused by this.

[0073] In this modified example, the light guide 2, as shown in Figure 16, comprises a base portion 21 having a reflective surface 2c and a plurality of third prism portions 7 parallel to the reflective surface 2c, and a prism sheet 22 having a plurality of first prism portions 3. The light guide 2 is formed, for example, by bonding the base portion 21 and the prism sheet 22 together with an optical adhesive (not shown).

[0074] The base portion 21, for example, has a prism array on the side opposite to the reflective surface 2c, where multiple third prism portions 7 are repeatedly arranged. Each third prism portion 7 has, for example, a fourth inclined surface 71 parallel to the reflective portion 41 and an adjacent surface 72. The fourth inclined surface 71 is the portion to which the prism sheet 22 is attached, forming part of the inner wall of the cavity layer 5. In other words, part of the fourth inclined surface 71 becomes the second reflective surface 5a. The inclination angle of the adjacent surface 72 with respect to the thickness direction D2 is appropriately adjusted so that total internal reflection of incident light does not occur.

[0075] The prism sheet 22 has a configuration in which, for example, the surface opposite to the ejection surface 2b has a plurality of protrusions 221 having a surface parallel to the adjacent surface 72, and a plurality of recesses 222 adjacent to the protrusions 221 and having a bottom surface parallel to the fourth inclined surface 71. The protrusions 221 come into contact with the adjacent surface 72 when the base 21 and the prism sheet 22 are bonded together, for example. On the other hand, the bottom surface of the recesses 222 is at a position away from the fourth inclined surface 71, so that they form, for example, a plate-shaped cavity layer 5.

[0076] This modified version also provides the same effects as the second embodiment described above, and by arranging the light-absorbing film 6 on the first inclined surface 31, it suppresses the intrusion of unwanted ambient light from the emission surface 2b side, resulting in an optical component 1 that suppresses the generation of noise and ghost images.

[0077] Furthermore, the optical member 1 may have a configuration in which, for example as shown in Figure 17, a reflective film 8 made of any material having a visible light reflectance of a predetermined or higher (not limited to, but for example, 99% or higher) is placed in place of the cavity layer 5. In this case, the optical member 1 has a reflective film 8 that is formed by any method such as sputtering instead of the recess 222. In this case as well, the optical member 1 can be formed by the same method as described above, and the same effects as the modified example can be obtained.

[0078] (Other embodiments) This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence range. In addition, various combinations and forms, as well as other combinations and forms including one, more, or less of those elements, fall within the scope and concept of this disclosure.

[0079] (1) For example, the optical member 1 may be configured by combining the first embodiment and any one of the first to third modifications of the second embodiment, or by combining the first or second modification of the second embodiment with the third modification. In this way, the optical member 1 can be configured by freely combining each embodiment and its modifications to the extent possible.

[0080] (2) Furthermore, the optical member 1 may have a configuration in which the back surface 2e is not a single surface connecting the ends 2a1 and 2c1 in a straight line, as shown in Figure 18, but rather has two or more surfaces between the ends 2a1 and 2c1. In this case, the angle between the virtual straight line VL when the ends 2a1 and 2c1 are connected in a straight line and the thickness direction D2 should be ξ (<φ). Also, the back surface 2e may be a curved surface. Thus, the shape of the back surface 2e is arbitrary in each of the above embodiments and its modifications.

[0081] (3) It goes without saying that, in each of the above embodiments, the elements constituting the embodiment are not necessarily essential unless explicitly stated to be particularly essential or unless they are clearly considered essential in principle. Furthermore, in each of the above embodiments, when numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiment are mentioned, the embodiment is not limited to those specific numbers unless explicitly stated to be particularly essential or unless it is clearly limited to a specific number in principle. Furthermore, in each of the above embodiments, when the shape, positional relationship, etc. of the components are mentioned, the embodiment is not limited to those shapes, positional relationships, etc. unless explicitly stated or unless it is clearly limited to a specific shape, positional relationship, etc. in principle. [Explanation of Symbols]

[0082] 2...light guide, 2a...incident surface, 2a1...end of the incident surface opposite to the exit surface 2b...exjection surface, 2c...reflecting surface, 2c1...end of the reflecting surface on the incident surface side 3...First prism section, 31...First inclined surface, 32...Second inclined surface, 33...Third inclined surface 4...Second prism section, 41...Reflecting section, 42...Adjacent surface D2...Thickness direction, Pa1~Pa(m+1)...Width of the first inclined surface Pb1~Pb(m+1)...Width from the second inclined surface to the third inclined surface Td: Maximum thickness of the incident surface (incident surface height), Ts: Distance between the ejection surface and the reflecting surface. VL…An imaginary line connecting the edge of the incident surface and the edge of the reflecting surface.

Claims

1. An optical component that reflects ambient light internally to guide it, The light guide (2) comprises an incident surface (2a) into which the ambient light is incident, an exit surface (2b) to which the incident light incident from the incident surface first reaches and which reflects and emits the incident light to the outside, and a reflective surface (2c) positioned opposite to the exit surface which reflects the reflected light from the exit surface toward the exit surface. The injection surface has a plurality of prism sections (3) which are composed of a plurality of inclined surfaces (31, 32, 33) that have different inclination angles and are inclined with respect to a reference surface of the injection surface. The optical member has a reflective surface which is the same inclined surface (41) as one of the plurality of inclined surfaces, with the same inclination angle.

2. The optical member according to claim 1, wherein one of the plurality of inclined surfaces that emits a portion of the incident light to the outside is designated as an emission section (33), and the emission section is parallel to the incident surface.

3. The plurality of prism sections constituting the ejection surface are referred to as the first prism section. The optical member according to claim 1, wherein the reflective surface has a plurality of second prism portions (4) having a reflective portion (41) which is a surface that reflects the light reflected from the incident light at the exit surface back to the exit surface, and adjacent surfaces (42) adjacent to the reflective portion.

4. The optical member according to claim 3, wherein the reflective portion is parallel to one of the plurality of inclined surfaces (31) that reflects the incident light.

5. Let n be the refractive index of the light guide, and let δ be the angle between the direction normal to one of the plurality of inclined surfaces that reflects the incident light (31) and the reflecting surface, and the direction in which the incident light travels. The optical member according to claim 1, wherein the one inclined surface and the reflective surface are inclined such that sinδ > 1 / n.

6. The direction connecting the ejection surface and the reflecting surface, perpendicular to the reference plane of the ejection surface, is defined as the thickness direction (D2), the angle between the incident direction of the ambient light on the incident surface and the thickness direction is defined as θ, the angle between the direction in which the incident light traveling toward the ejection surface travels and the thickness direction is defined as φ, and the angle between the direction in which the incident light traveling toward the reflecting surface travels and the thickness direction is defined as ε. The optical member according to claim 1, wherein one of the plurality of inclined surfaces that reflects the incident light (31), and the incident surface are inclined such that ε > φ > θ.

7. The direction connecting the ejection surface and the reflective surface, which is perpendicular to the reference plane of the ejection surface, is defined as the thickness direction (D2), the angle between the direction in which the incident light traveling toward the ejection surface propagates and the thickness direction is defined as φ, and the angle between the incident surface and the thickness direction is defined as ψ. The optical member according to claim 1, wherein the incident surface is inclined such that ψ < φ.

8. The optical member according to claim 1, wherein the injection surface has three or more of the inclined surfaces.

9. In the light guide, the direction in which the incident light is reflected and propagated by the emission surface and the reflection surface, and which is parallel to the reference surface of the emission surface, is defined as the light guide direction (D1), and of the plurality of inclined surfaces, one surface that reflects a portion of the incident light is defined as the first inclined surface (31), the surface adjacent to the first inclined surface is defined as the second inclined surface (32), and the surface located on the opposite side of the second inclined surface from the first inclined surface, which emits a portion of the incident light to the outside, is defined as the third inclined surface (33). The ejection surface has a plurality of regions (2ba to 2bc) in which the ratio of the first width (Pa1 to Pa(m+1)) of the first inclined surface in the light guide direction to the second width (Pb1 to Pb(m+1)) from the second inclined surface to the third inclined surface in the light guide direction is different. The optical member according to claim 8, wherein the ratio of the first width to the second width is smaller for each of the multiple regions that are located further from the incident surface.

10. The direction connecting the injection surface and the reflective surface, which is perpendicular to the reference plane of the injection surface, is defined as the thickness direction (D2), and the distance from the injection surface to the end of the incident surface opposite to the injection surface (2a1) is defined as the incident surface height (Td). The incident surface height is greater than the distance (Ts) between the injection surface and the reflective surface in the thickness direction. Let ξ be the angle between the imaginary straight line (VL) connecting the end portion and the end portion of the reflective surface on the incident surface side (2c1) and the thickness direction, and let φ be the angle between the direction in which the incident light traveling toward the emission surface propagates and the thickness direction. The optical member according to claim 1, wherein the light guide satisfies ξ < φ.

11. With the aforementioned reflective surface as the first reflective surface, the light guide has a second reflective surface (5a, 8) inside that reflects the incident light to the first reflective surface. The optical member according to claim 1, wherein the second reflective surface is parallel to the same inclined surface among the first reflective surfaces.

Images