Optical member

Abstract

To provide an optical member capable of suppressing the occurrence of a ghost image resulting from incident light from other than an incident plane while using a light guide formed of a light transmissive material.SOLUTION: An optical member 1 includes a light guide 2 formed of the light transmissive material, and a shading reverse cover 3 covering the whole area on the reflection surface, the light guide 2 having an incident part 2a consisting of a plurality of protruded incident prism parts 21, a reflection surface 2d neighboring the incident part, and an emission surface 2c for reflecting part of the incident light entering inside from the incident part 2a to the side of the reflection surface 2d with total reflection, the incident prism part 21 having an incident surface 21a as a surface where outside view light enters into the light guide, and an adjacent surface 21b as a surface adjacent to the incident surface, the reverse cover 3 being arranged abutting on the adjacent surface 21b of a rear prism part 211 adjacent to the reflection surface 2d out of the plurality of incident prism pars 21, while being spaced from the reflection surface 2d.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an optical member using a light guide that internally reflects part of the 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 Art

[0002] Conventionally, this type of optical member is, for example, attached to a light-shielding body, allows external light from a dead angle area generated by the light-shielding body to enter internally, reflects it internally, and emits the external light from a surface different from the incident surface of the external light, thereby serving as a dead angle assisting device for visually recognizing the dead angle area. Examples of such an optical member include those described in Patent Document 1.

[0003] The optical member described in Patent Document 1 is composed of a light-transmissive light guide. Part of the external light incident from the incident surface of the light guide is guided by total internal reflection inside, and is emitted to the outside from an emission part different from the incident surface, allowing a user on the emission surface side to visually recognize the external view of the dead angle. As a result, a half-mirrorless structure is achieved without the need for a half-mirror made of a reflective material different from the light guide on the emission part side, and losses due to absorption of external light in light guiding inside the light guide and variations in brightness due to wavelength are reduced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since the light guide in the optical member described in Patent Document 1 is made of a light-transmissive material, when it is attached to another light-shielding member, external scene light enters from the surface of the light guide other than the incident surface and facing the other light-shielding member. When the external scene light incident from the surface of the light guide other than the incident surface is emitted from the emission surface, it is visually recognized by the user as a ghost image.

[0006] Therefore, it is conceivable to form a light-shielding film on the surface of the light guide made of a light-transmissive material other than the incident surface and the emission surface. However, since the above optical member is configured to guide the incident light inside the light guide by total reflection, if a light-shielding film is formed, the total reflection condition will not be satisfied, and the user on the emission surface side will not be able to visually recognize the external scene in the blind spot.

[0007] In view of the above points, an object of the present disclosure is to provide an optical member that can suppress the generation of ghost images caused by incident light from other than the incident surface while using a light guide made of a light-transmissive material.

Means for Solving the Problems

[0008] According to one aspect of the present disclosure, there is provided an optical member, an incident portion (2a) including a plurality of protruding incident prism portions (21), a reflection surface (2d) adjacent to the incident portion, and an emission surface (2c) facing the incident portion and the reflection surface, which emits a part of the incident light (L2) incident from the incident portion to the outside and reflects the other part of the incident light to the side of the reflection surface by total reflection, and a light guide (2) made of a light-transmissive material, and a light-shielding back cover (3) covering at least the entire area of the reflection surface of the light guide. The surface of the incident prism portion that allows external scene light to enter the light guide is defined as the incident surface (21a), the surface adjacent to the incident surface is defined as the adjacent surface (21b), and the incident prism portion adjacent to the reflection surface among the plurality of incident prism portions is defined as the rear prism portion (211). The back cover abuts against the adjacent surface of the rear prism portion and is disposed with a gap from the reflection surface.

[0009] This optical member has a light guide with a mirrorless structure capable of light guiding by total reflection and a back cover, and the back cover covers the entire reflection surface facing a light shielding body (not shown) of the light guide with a gap therebetween. Thus, it becomes an optical member capable of suppressing the generation of ghost images caused by light entering the reflection surface from other than the incident surface of the light guide while using the light guide with a mirrorless structure.

[0010] Note that the reference signs with parentheses attached to each component etc. indicate an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are identical or equivalent to each other will be described with the same reference numerals.

[0013] (First Embodiment) The optical member 1 of the first embodiment will be described.

[0014] 〔Basic Configuration〕 The optical member 1 of the present embodiment is, for example, attached to a member or an obstacle that blocks the user's field of view and creates a blind spot, and is used as a blind spot assist device that allows the user to visually recognize the scenery in the blind spot area. The optical member 1 is, for example, in the case of in-vehicle use, attached to a predetermined light-shielding body such as a pillar of the vehicle to be mounted, guides the external scene light from the area that becomes a blind spot by the light-shielding body to the user's side, and allows the user to visually recognize the scenery in the blind spot area.

[0015] The optical member 1 of the present embodiment has, for example, as shown in FIG. 1, a light guide 2 and a back cover 3, and these are attached to a light-shielding body (not shown), and the back cover 3 is used in a state of facing the light-shielding body. The optical member 1 is configured to guide the external scene light inside the light guide 2 and emit it to the user side to allow the blind spot area to be visually recognized, and to prevent unnecessary light from entering the light guide 2 by the back cover 3.

[0016] As shown in FIG. 1 for example, the light guide 2 has a member including an incident portion 2a, a reflecting surface 2d adjacent to the incident portion 2a, an emitting surface 2c facing the incident portion 2a and the reflecting surface 2d, a side surface 2b connecting the incident portion 2a and the emitting surface 2c, and a terminal surface 2e connecting the emitting surface 2c and the reflecting surface 2d. As shown in FIG. 2 for example, the light guide 2 has an upper surface 2f and a lower surface 2g which are surfaces connecting the incident portion 2a, the side surface 2b, the emitting surface 2c, the reflecting surface 2d and the terminal surface 2e and facing each other. The light guide 2 is a transparent member which is a single member made of a light-transmissive material. As the light-transmissive material, for example, resin materials such as polyethylene terephthalate, polycarbonate, polyethylene, acrylic, or inorganic materials such as glass can be used. The light guide 2 has a mirrorless structure without a mirror made of a reflective material different from the light-transmissive material, and is designed to guide light by totally reflecting the incident light from the incident portion 2a inside. Since the light guide 2 has many common parts with those described in Patent Document 1, the characteristic parts will be mainly described in this specification.

[0017] As shown in FIG. 1 for example, the incident portion 2a is formed by repeatedly and continuously arranging a plurality of incident prism portions 21 which are triangular protrusions in a cross-sectional view with their extending directions aligned. As shown in FIG. 3 for example, one surface of the outer surface of the plurality of incident prism portions 21, which is opposite to the reflecting surface 2d adjacent to the incident portion 2a, is an incident surface 21a for allowing a part of the external scene light L1 to enter inside. The heights of the portions protruding from the reflecting surface 2d of the plurality of incident prism portions 21 are aligned to be substantially the same, and the incident surfaces 21a of each are arranged to be substantially parallel. "Substantially the same" includes cases where, in addition to being exactly the same, they are not exactly the same due to unavoidable errors such as processing errors but are approximately the same. One surface of the outer surface of the plurality of incident prism portions 21 on the reflecting surface 2d side is an adjacent surface 21b. The adjacent surface 21b has an inclination angle of a predetermined value or less so as not to inhibit the incidence of the external scene light L1 on the incident surface 21a of another adjacent incident prism portion 21.

[0018] Hereinafter, for convenience of explanation, as shown in FIG. 3, of the incident part 2a and the external scene light L1 from the reflection surface 2d side, the light that enters the interior from the incident part 2a is referred to as "incident light L2", and of the incident light L2, the light that is emitted to the outside from the emission prism part 22 described later is referred to as "emitted light L3". Note that in FIG. 2, in order to make the configuration of the optical member 1 easier to understand, a part of the outer contour of the light guide 2 and the back cover 3 described later that cannot be seen from the angle of FIG. 2 is shown by a dashed line.

[0019] The side surface 2b has, for example, an inclination of the plane formed by the surface such that the incident angle φ of the incident light L2 to the flat part 23 is φ or more so that the incident light L2 is not emitted to the outside from the side surface 2b. Note that the incident angle φ of the incident light L2 is the angle formed by the normal direction (hereinafter simply referred to as the "normal direction") with respect to the plane formed by the flat part 23 or the reflection surface 2d and the traveling direction of the incident light L2. The light guide 2 has a refractive index of the constituent material of n, and with the external medium being air (refractive index = 1), by satisfying the total reflection condition of the following formula (1), light guiding in a mirrorless structure is possible.

[0020] sinφ≧1 / n···(1) The emission surface 2c has, for example, a plurality of emission prism parts 22 that are triangular protrusions in a cross-sectional view, and a plurality of flat parts 23 that are adjacent to these and are planes substantially parallel to the reflection surface 2d. The emission surface 2c is the surface that the incident light L2 from the incident part 2a first reaches, and the emission prism parts 22 and the flat parts 23 are alternately and repeatedly arranged. The plurality of emission prism parts 22 have an emission part 22a that is the surface for emitting the incident light L2 to the outside and another surface 22b adjacent to this, and for example, are arranged in parallel with the extending directions aligned. The emission part 22a is, for example, parallel to the incident surface 21a. The plurality of flat parts 23 are, for example, flat surfaces located on the same plane, and are the first reflection surfaces that reflect the incident light L2 toward the reflection surface 2d by total reflection.

[0021] Hereinafter, for convenience of explanation, the direction orthogonal to the extending direction of the emission prism portion 22 and along the arrangement direction of the plurality of emission prism portions 22 is referred to as the "first direction D1", and the direction along the above normal direction is referred to as the "second direction D2". Also, the direction along the extending direction of the incident prism portion 21 and the emission prism portion 22 is referred to as the "third direction D3". Among the first direction D1, the direction from the side surface 2b toward the end surface 2e is the direction in which the incident light L2 is guided, and can also be said to be the light guiding direction. The second direction D2 corresponds to the thickness direction of the light guide 2.

[0022] The reflecting surface 2d is a second reflecting surface that reflects the incident light L2 reflected by the flat portion 23 to the emission surface 2c side by total reflection. When the emission surface 2c directed toward the user side is the surface, the reflecting surface 2d is the surface corresponding to the back surface. The entire area of the reflecting surface 2d is covered by the back cover 3 with a gap so that the external scene light L1 does not enter.

[0023] Here, for example, as shown by the broken-line arrow in FIG. 3, if the back cover 3 is not provided, a part of the external scene light L1 directly enters the inside from the reflecting surface 2d, and this incident light is emitted as unintended ghost light L4 from the emission surface 2c. When the ghost light L4 reaches the user's eyes together with the emission light L3, the user will visually recognize the scene due to the ghost light L4 as well as the scene in the dead angle area due to the emission light L3. In order to suppress the generation of such ghost images and improve the visibility of the dead angle area, the optical member 1 has a structure that prevents the external scene light L1 from entering the reflecting surface 2d by the back cover 3.

[0024] The end surface 2e is the surface where a part of the incident light L2 finally reaches. The end surface 2e may form a single plane together with the emission portion 22a of the emission prism portion 22, may have other surface shapes, and may have an arbitrary shape.

[0025] The upper surface 2f and the lower surface 2g are non-optical surfaces that are not used for guiding, i.e., reflecting, the incident light L2 inside the light guide 2, similar to the side surface 2b. The upper surface 2f and the lower surface 2g are each, for example, a single flat surface connecting the incident portion 2a, the light emitting surface 2c, the reflecting surface 2d, and the end surface 2e, and are arranged in parallel, but may have an arbitrary shape as long as it does not hinder the guiding of the incident light L2.

[0026] The back cover 3 is a light-shielding member that prevents the external scene light L1 from entering the reflecting surface 2d. The back cover 3 is, for example, in the shape of a flat plate and may be entirely composed of an arbitrary light-shielding material such as resin or metal, or may have a configuration in which part or all of the outer surface is painted with black paint or the like. Thus, the back cover 3 only needs to be configured not to transmit light, and the material and configuration can be appropriately changed. The back cover 3 is preferably composed of, for example, a black light-shielding member having a visible light absorption rate of a predetermined value or more.

[0027] The back cover 3 preferably has, for example, a surface facing the reflecting surface 2d that is a rough surface that is less likely to reflect light compared to a mirror surface. Thereby, for example, when external light from the light emitting surface 2c enters the light guide 2 and is emitted from the reflecting surface 2d to the back cover 3, the suppression of the reflection of the emitted light on the surface of the back cover 3 improves the visibility of the dead angle region visually recognized by the user by the light emitting surface 2c. Here, the rough surface means a surface that has not been subjected to a flattening process such as mirror finishing with a surface roughness of a predetermined value or less.

[0028] For example, as shown in FIG. 4, the back cover 3 is composed of a plate member 31 and an elastic body 32 attached to the end of the plate member 31. The plate member 31 has an arbitrary configuration that does not transmit light. The back cover 3 is arranged such that, among the plurality of incident prism portions 21, the one closest to the reflecting surface 2d is defined as the rear prism portion 211, and the elastic body 32 abuts against the adjacent surface 21b of the rear prism portion 211. The elastic body 32 is a member having light-shielding properties and elasticity, such as black rubber, for example. While preventing the rear prism portion 211 from being damaged by contact with the back cover 3, it fills the gap between the rear prism portion 211 and the plate member 31, thereby serving to prevent light from entering the reflecting surface 2d. The back cover 3 is arranged with a gap so that the plate member 31 and the elastic body 32 do not contact the reflecting surface 2d, so as not to inhibit the total reflection of the incident light L2 on the reflecting surface 2d.

[0029] Note that if a black paint is applied to the reflecting surface 2d of the light guide 2 to form a light-shielding film, the total reflection condition of the above formula (1) will not be satisfied, and the light guiding function will be impaired. Therefore, the light guide 2 having a mirrorless structure cannot be directly processed for light shielding on the reflecting surface 2d.

[0030] The back cover 3 has a width Wr1 in the first direction D1 of the reflecting surface 2d of the light guide 2 and a width Wr2 in the third direction D3. The width in the first direction D1 is set to Wc1 that is Wr1 or more, and the width in the third direction D3 is set to Wc2 that is Wr2 or more. In other words, the back cover 3 has a planar size that is equal to or larger than the reflecting surface 2d so as to cover the entire area of the reflecting surface 2d. Thereby, the back cover 3 prevents external scene light L1 from entering the reflecting surface 2d and suppresses the generation of ghost images.

[0031] According to the present embodiment, there is provided an optical member 1 having a mirrorless structure light guide 2 capable of light guiding by total reflection and a back cover 3, and the back cover 3 covers the entire area of the reflecting surface 2d of the light guide 2 facing a light shielding body (not shown) with a gap. Thus, it becomes an optical member 1 that can suppress the generation of ghost images caused by light from outside the incident surface 21a of the light guide 2 while using the mirrorless structure light guide 2. Further, the optical member 1 can also obtain the following effects.

[0032] (1) The optical member 1 has a rough surface on the surface of the back cover 3 that faces the light guide 2 without undergoing a smoothing process. As a result, surface reflection of light on the surface of the back cover 3 is suppressed, and the incidence of unintended light toward the emission surface 2c is reduced, making it possible to further improve the visibility of the dead angle region on the emission surface 2c side.

[0033] (2) The optical member 1 has a light-shielding elastic body 32 at the portion of the back cover 3 that contacts the rear prism portion 211 of the light guide 2. As a result, while preventing the light guide 2 from being damaged by the back cover 3, the gap at the contact portion between the rear prism portion 211 of the light guide 2 and the back cover 3 is filled, and the effect of further suppressing the direct incidence of external scene light L1 on the reflection surface 2d is obtained.

[0034] (Second Embodiment) The optical member 1 of the second embodiment will be described.

[0035] The optical member 1 of the present embodiment is different from the first embodiment in that, for example, as shown in FIG. 5, it has a holder 10 for the light guide 2 that includes a part of the back cover 3. In the present embodiment, this difference will be mainly described.

[0036] In FIG. 5, similar to FIG. 1, a part of the outline of the light guide 2 that cannot be seen at the angle shown in FIG. 5 is indicated by a broken line, and a part of the outline of the upper cover 4 and the lower cover 5 to be described later is also indicated by a broken line in the same way. This is the same for FIG. 11 to be described later. In FIG. 6, the outline of the portion of the light guide 2 that overlaps with the holder 10 and the portion of the outline of the upper cover 4 to be described later that cannot be seen at the angle shown in FIG. 6 are indicated by broken lines. This is the same for FIG. 9 to be described later. Note that FIG. 7 is a cross-sectional view at the position of the flat portion 23 of the emission surface 2c.

[0037] The holder 10 includes, for example, as shown in FIG. 5, in addition to the back cover 3, an upper cover 4 and a lower cover 5.

[0038] The upper cover 4 faces the upper surface 2f of the light guide 2 and is a member that holds the upper surface 2f of the light guide 2. For example, a groove-shaped recess 41 for holding the light guide 2 is formed on the facing surface 4a of the upper cover 4 that faces the upper surface 2f of the light guide 2. As shown in FIG. 6, for example, the upper cover 4 has a surface adjacent to the facing surface 4a and on the reflection surface 2d side rather than the emission surface 2c of the light guide 2 as the end surface 4b, and the back cover 3 is attached to the end surface 4b. The upper cover 4 has a width in the first direction D1 that is larger than the width of the back cover 3 in the same direction and covers the entire area of the upper surface 2f of the light guide 2. The upper cover 4 has a curved shape with the end of the injection side surface 4c, which is the surface on the opposite side of the end surface 4b, chamfered. As a result, the surface of the upper cover 4 on the user side has a rounded shape without corners, preventing the user from getting injured.

[0039] The lower cover 5 is a member that pairs with the upper cover 4 and is used to hold the light guide 2 together with the upper cover 4. For example, the lower cover 5 faces the lower surface 2g of the light guide 2, and a groove-shaped recess 51 for holding the light guide 2 is formed on the facing surface 5a that faces the lower surface 2g. The lower cover 5 has a width in the first direction D1 that is larger than the width of the back cover 3 in the same direction and covers the entire area of the lower surface 2g of the light guide 2. As shown in FIG. 7, for example, the lower cover 5 basically has the same structure as the upper cover 4, and the back cover 3 is attached to the end surface 5b, which is a surface adjacent to the facing surface 5a and located on the reflection surface 2d side rather than the emission surface 2c of the light guide 2. For example, for the same reason as the upper cover 4, the lower cover 5 has a curved shape with the end of the injection side surface 5c, which is the opposite surface of the end surface 5b, chamfered.

[0040] Note that the back cover 3 may be integrated with the upper cover 4 and the lower cover 5, or may be a separate body. In the latter case, it is attached to the upper cover 4 and the lower cover 5 by any method such as fastening members such as screws (not shown) or an adhesive. Also, the back cover 3 is attached so as to connect the two covers at a position closer to the end faces 4b and 5b than the recesses 41 and 51 on the upper cover 4 and the lower cover 5. Thereby, the holder 10 can hold the light guide 2 while securing a gap between the reflecting surface 2d of the light guide 2 and the back cover 3. For example, as shown in FIG. 8, the back cover 3 may be attached not to the end faces 4b and 5b of the covers 4 and 5, but to the opposing faces 4a and 5a on the side closer to the end faces 4b and 5b than the recesses 41 and 51.

[0041] It is preferable that at least the surfaces of the upper cover 4 and the lower cover 5 facing the light guide 2 are rough surfaces with light-shielding properties. Thereby, external light does not enter the upper surface 2f or the lower surface 2g of the light guide 2 from the upper cover 4 and the lower cover 5 sides, and surface reflection of light on the opposing faces 4a and 5a is suppressed, making it difficult for unintended light to reach the emission surface 2c and improving the visibility of the dead angle region. The upper cover 4 and the lower cover 5 are, like the back cover 3, partially or entirely made of an arbitrary material with light-shielding properties.

[0042] In the present embodiment, for example, the light guide 2 has a structure in which both ends of the incident prism portion 21 and the emission prism portion 22 do not reach the upper surface 2f and the lower surface 2g as shown in FIG. 5 so that it can be attached to the upper cover 4 and the lower cover 5. Thereby, the prism portions 21 and 22 of the light guide 2 can be inserted without interfering with the recesses 41 and 51 of the upper cover 4 and the lower cover 5, and can be held by the holder 10. Also, the light guide 2 may have any shape that can be attached to the holder 10, such as a structure having protrusions on the upper surface 2f and the lower surface 2g that match the width of the recesses 41 and 51, or the structure may be appropriately changed within a range that does not hinder the guiding of the incident light L2. The same applies to the upper cover 4 and the lower cover 5.

[0043] According to the present embodiment, in addition to the above-described first embodiment, an optical member 1 having a structure that can be fixed to a light-shielding member (not shown) while maintaining the positional relationship between the light guide 2 and the back cover 3 is provided. Further, the optical member 1 can also obtain the following effects.

[0044] (1) The optical member 1 has a structure in which the upper cover 4 and the lower cover 5 each have recesses 41 and 51 for holding the light guide 2. Thereby, the optical member 1 is held in a state where the light guide 2 is fitted into the recesses 41 and 51 of the upper cover 4 and the lower cover 5 that form a pair in the holder 10.

[0045] (2) The optical member 1 is attached so as to connect the upper cover 4 and the lower cover 5 at a position where the back cover 3 is closer to the end faces 4b and 5b side than the recesses 41 and 51 of the upper cover 4 and the lower cover 5. Thereby, the optical member 1 has a structure in which a gap between the reflection surface 2d of the light guide 2 and the back cover 3 is secured while holding the light guide 2 by the holder 10.

[0046] (3) The optical member 1 has a light-shielding rough surface on the surfaces of the upper cover 4 and the lower cover 5 that face the light guide 2. Thereby, the intrusion of external light from the upper cover 4 and lower cover 5 sides into the light guide 2 and the surface reflection of light on the surfaces of both covers on the light guide 2 side are suppressed, and the visibility of the dead angle region by the light guide 2 is further improved.

[0047] (4) The optical member 1 has the upper cover 4 and the lower cover 5 with a width in the first direction D1 corresponding to the light guide direction being larger than that of the back cover 3, covering the entire upper surface 2f and lower surface 2g. Thereby, the intrusion of unintended external light into the upper surface 2f and lower surface 2g of the light guide 2 is prevented, and the visibility of the dead angle region by the light guide 2 is further improved.

[0048] (5) The optical member 1 has a curved shape without corners at the ends of the injection side surfaces 4c and 5c of the upper cover 4 and the lower cover 5. Thereby, the end portions of the part of the holder 10 facing the user side have a rounded shape without sharp corners, and the structure can prevent the user from being injured.

[0049] (Embodiment 3) The optical member 1 of the third embodiment will be described.

[0050] The optical member 1 of the present embodiment is different from the second embodiment in that the holder 10 further has a rear cover 6, as shown in FIG. 9, for example. In the present embodiment, this difference will be mainly described.

[0051] In FIGS. 9 and 10, portions of the outer contour of the rear cover 6 that are not visible at the angle shown in FIG. 9 are indicated by broken lines. In FIG. 10, as in FIG. 2, portions of the outer contour of the back cover 3 that are not visible are indicated by broken lines.

[0052] In the present embodiment, the holder 10 has, in addition to the back cover 3, the upper cover 4, and the lower cover 5, a rear cover 6 that further covers the end face 2e side of the light guide 2. The holder 10 has, with the side face 2b of the light guide 2 as the front face and the end face 2e as the rear face, in the present embodiment, in addition to the upper face 2f and the lower face 2g of the light guide 2, further covers the end face 2e, and the portion excluding the back cover 3 has a U-shaped configuration.

[0053] The rear cover 6 is a member that connects the upper cover 4 and the lower cover 5, covers the end face 2e side of the light guide 2, and holds the light guide 2. For example, the rear cover 6 has a groove-shaped recess 61 formed in the opposing surface 6a that faces the end face 2e of the light guide 2 for holding the light guide 2. Note that the recess 61 may have a shape that fits with a part or all of the end face 2e, and its shape, dimensions, etc. can be appropriately changed according to the shape of the end face 2e of the light guide 2. The rear cover 6 has a width in the third direction D3 that is larger than the width of the back cover 3 in the same direction and covers the entire area of the end face 2e of the light guide 2. The rear cover 6 has basically the same structure as the upper cover 4 and the lower cover 5, as shown in FIG. 10, for example. The back cover 3 is attached to the end face 6b that is adjacent to the opposing surface 6a and is located on the reflection surface 2d side rather than the light emitting surface 2c of the light guide 2. The rear cover 6 has a curved shape with chamfered ends at the injection side surface 6c, which is the opposite surface of the end face 6b, for the same reason as the upper cover 4 and the lower cover 5, for example.

[0054] In this embodiment, the upper cover 4 and the lower cover 5 have a curved shape with chamfered ends of the injection side surfaces 4c and 5c excluding the rear cover 6 side, and the ends on the rear cover 6 side are flat surfaces without a step due to the attachment of the rear cover 6.

[0055] The rear cover 6 may be integral with part or all of the back cover 3, the upper cover 4, and the lower cover 5, or may be separate. In the latter case, it is attached to the upper cover 4 or the like by any method such as fastening members or adhesives (not shown). By having the rear cover 6, the holding body 10 has a structure that can more stably hold and fix the light guide 2 while preventing misalignment between the upper cover 4 and the lower cover 5. Also, in this embodiment, the back cover 3 may be attached to the ribs formed by the portions on the end face 4b to 6b side of the concave portions 41, 51, 61 among the opposing faces 4a, 5a, 6a of the covers 4, 5, 6. Further, it is preferable that the covers 4, 5, 6 have a larger thickness, i.e., width in the second direction D2, except for the portions facing the incident prism portion 21 among the ribs, as this can surely ensure a gap between the back cover 3 and the reflecting surface 2d of the light guide 2.

[0056] For example, it is preferable that at least the opposing face 6a of the rear cover 6 is a rough surface with light-shielding properties. This can suppress the intrusion of unintended external light into the end face 2e through the rear cover 6 and the surface reflection of light on the opposing face 6a of the rear cover 6, further improving the visibility of the dead angle region by the light guide 2. Similar to the upper cover 4 and the lower cover 5, the rear cover 6 may be made of any material with light-shielding properties not only for the opposing face 6a but also entirely.

[0057] According to this embodiment, in addition to the effects of the second embodiment, the optical member 1 has a structure that can more stably hold and fix the light guide 2 while preventing misalignment between the upper cover 4 and the lower cover 5. Also, the following effects can be obtained for the optical member 1.

[0058] (1) In the optical member 1, at least the face of the rear cover 6 facing the light guide 2 is a rough surface with light-shielding properties. This can suppress the intrusion of external light into the end face 2e through the rear cover 6 and the surface reflection of light on the opposing face 6a, and also obtain the effect of further improving the visibility of the dead angle region by the light guide 2.

[0059] (2) The optical member 1 has a recess 61 on the opposing surface 6a of the rear cover 6 for holding the light guide 2. As a result, in addition to the upper cover 4 and the lower cover 5, the optical member 1 can also hold the light guide 2 by the rear cover 6, and the structure for fixing the light guide 2 becomes more stable.

[0060] (3) Similar to the upper cover 4 and the lower cover 5, the optical member 1 has a structure that can prevent the user from being injured by making the end of the injection side surface 6c of the rear cover 6 have a curved shape without corners.

[0061] (Fourth Embodiment) The optical member 1 of the fourth embodiment will be described.

[0062] The optical member 1 of the present embodiment is different from the second embodiment in that, for example, as shown in FIG. 11, ribs 24 are formed near the end of the reflecting surface 2d of the light guide 2. In the present embodiment, this difference will be mainly described.

[0063] In the present embodiment, the light guide 2 has, for example, protruding rib-shaped ribs 24 projecting from the reflecting surface 2d near the upper surface 2f and the lower surface 2g of the reflecting surface 2d. As shown in FIG. 12, for example, the ribs 24 are formed inside the portions inserted into the recess 41 of the upper cover 4 and the recess 51 of the lower cover 5 of the reflecting surface 2d, and two ribs 24 are formed at both ends or in the vicinity thereof in the third direction D3. The two ribs 24 are, for example, linearly extended along the first direction D1 and arranged in parallel. The ribs 24 are parts that prevent the rear cover 3 from contacting the reflecting surface 2d of the light guide 2 and inhibiting the total reflection of the incident light L2 on the reflecting surface 2d even when the rear cover 3 is deformed by heat or the like.

[0064] Note that the ribs 24 are, for example, part of the light guide 2 and are formed by a molding method using a mold (not shown) similar to the prism parts 21 and 22. The ribs 24 are formed at both ends or in the vicinity thereof in the third direction D3, and it is only necessary to prevent the rear cover 3 from contacting the reflecting surface 2d, and the number, shape, etc. thereof may be appropriately changed.

[0065] According to the present embodiment, in addition to the effects of the second embodiment, the optical member 1 has a structure that more reliably prevents the back cover 3 from contacting the reflecting surface 2d of the light guide 2.

[0066] (Other embodiments) Although the present disclosure has been described based on examples, it should be understood that the present disclosure is not limited to such examples and structures. The present disclosure includes various modifications and modifications within an equivalent range. In addition, various combinations and forms, and further, other combinations and forms including only one of those elements, more, or less, fall within the scope and spirit of the present disclosure.

[0067] In addition, in each of the above embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where it is explicitly stated that they are particularly essential and cases where they are considered to be clearly essential in principle. Further, in each of the above embodiments, when numerical values such as the number, numerical value, amount, range, etc. of the components of the embodiment are mentioned, they are not limited to the specific number, except in cases where it is explicitly stated that they are particularly essential and cases where they are clearly limited to a specific number in principle. Further, in each of the above embodiments, when referring to the shape, positional relationship, etc. of the components, etc., they are not limited to the shape, positional relationship, etc., except in cases where it is explicitly stated and cases where they are clearly limited to a specific shape, positional relationship, etc. in principle.

[0068] (Viewpoint of the present disclosure) The above-described present disclosure can be grasped from, for example, the viewpoints shown below.

[0069] [First viewpoint] An optical member, An incident portion (2a) composed of a plurality of protruding incident prism portions (21), a reflecting surface (2d) adjacent to the incident portion, and a light emitting surface (2c) facing the incident portion and the reflecting surface, which emits a part of the incident light (L2) incident from the incident portion to the outside and reflects the other part of the incident light to the side of the reflecting surface by total reflection, and a light guide (2) made of a translucent material. A light-shielding back cover (3) that covers at least the entire area of the reflecting surface of the light guide. Of the incident prism portions, the surface that allows external light to enter the inside of the light guide is defined as an incident surface (21a), the surface adjacent to the incident surface is defined as an adjacent surface (21b), and among the plurality of incident prism portions, the incident prism portion adjacent to the reflecting surface is defined as a rear prism portion (211). The back cover is an optical member that abuts against the adjacent surface of the rear prism portion and is disposed with a gap from the reflecting surface. [Second aspect] The surface of the back cover facing the reflecting surface is a rough surface, and the optical member according to the first aspect. [Third aspect] The portion of the back cover that abuts against the rear prism portion is an elastic body (32) having light-shielding properties, and the optical member according to the first or second aspect. [Fourth aspect] The light guide has an upper surface (2f) and a lower surface (2g) which are two surfaces connecting the incident portion, the light emitting surface and the reflecting surface. The back cover constitutes a part of a holding body (10) that holds the light guide. The holding body further includes, in addition to the back cover, an upper cover (4) facing the upper surface and holding the upper surface, and a lower cover (5) facing the lower surface and holding the lower surface, and the optical member according to any one of the first to third aspects. [Fifth aspect] The upper cover has a recess (41) that holds the upper surface of the light guide. The lower cover has a recess (51) that holds the lower surface of the light guide, and the optical member according to the fourth aspect. [Sixth aspect] An end face (4b, 5b) is defined as a face adjacent to the face on which the recess is formed among the upper cover and the lower cover, and is closer to the reflecting face than the emitting face. The back cover is attached so as to connect the upper cover and the lower cover at a position closer to the end face than the recess among the upper cover and the lower cover, for the optical member according to the fifth aspect. [Seventh aspect] For the optical member according to any one of the fourth to sixth aspects, the opposing faces (4a, 5a) of the upper cover and the lower cover facing the light guide are light-shielding faces and rough faces. [Eighth aspect] A light guiding direction (D1) is defined as a direction orthogonal to the extending direction of the incident prism part and along the direction in which the plurality of incident prism parts are arranged. For the optical member according to any one of the fourth to seventh aspects, the upper cover and the lower cover have a width in the light guiding direction that is larger than the width of the back cover in the light guiding direction. [Ninth aspect] An end face (2e) is defined as a face connecting the emitting face, the reflecting face, the upper face and the lower face of the light guide. The holder is located on the side of the end face and further has a back cover (6) connecting at least the upper cover and the lower cover, for the optical member according to any one of the fourth to eighth aspects. [Tenth aspect] For the optical member according to the ninth aspect, the face (6a) of the back cover facing the light guide is a light-shielding face and a rough face. [Eleventh aspect] The back cover faces the end face and has a recess (61) for holding the end face, for the optical member according to the ninth or tenth aspect. [Twelfth aspect] An emitting side face (4c, 5c, 6c) is defined as a face adjacent to the opposing faces (4a, 5a, 6a) of the upper cover, the lower cover and the back cover facing the light guide, and is closer to the emitting face side than the reflecting face. The upper cover, the lower cover, and the rear cover are the optical member according to any one of the ninth to eleventh aspects, wherein an end portion of the injection side surface has a curved shape without corners. [Aspect 13] The light guide has protruding rib (24) protruding from the reflection surface in the vicinity of the upper surface and the lower surface of the reflection surface, and is the optical member according to any one of the fourth to twelfth aspects.

Explanation of Reference Numerals

[0070] 2... light guide, 2a... incident portion, 2c... emission surface, 2d... reflection surface, 2e... end surface, 2f... upper surface, 2g... lower surface, 21... incident prism portion, 21a... incident surface, 21b... adjacent surface, 211... rear prism portion, 24... rib, 3... back cover, 32... elastic body, 4... upper cover, 4a... opposing surface of the upper cover, 4b... end surface of the upper cover, 4c... incident side surface of the upper cover, 41... recess of the upper cover, 5... lower cover, 5a... opposing surface of the lower cover, 5b... end surface of the lower cover, 5c... incident side surface of the lower cover, 51... recess of the lower cover, 6... rear cover, 6a... opposing surface of the rear cover, 6c... incident side surface of the rear cover, 61... recess of the rear cover, 10... holder, D1... light guide direction (first direction), L2... incident light

Claims

1. An optical member, comprising: an incident portion (2a) formed by a plurality of protruding incident prism portions (21); a reflecting surface (2d) adjacent to the incident portion; and an emitting surface (2c) facing the incident portion and the reflecting surface, which emits a part of incident light (L2) incident from the incident portion to the outside and reflects the other part of the incident light to the side of the reflecting surface by total reflection, and the light guide (2) is made of a translucent material; a light-shielding back cover (3) that covers at least the entire area of the reflecting surface of the light guide; wherein, among the incident prism portions, the surface for allowing external light to enter the inside of the light guide is defined as an incident surface (21a), the surface adjacent to the incident surface is defined as an adjacent surface (21b), and among the plurality of incident prism portions, the incident prism portion adjacent to the reflecting surface is defined as a rear prism portion (211); the back cover abuts against the adjacent surface of the rear prism portion and is disposed with a gap from the reflecting surface.

2. The optical member according to claim 1, wherein the surface of the back cover facing the reflecting surface is a rough surface.

3. The optical member according to claim 1, wherein the portion of the back cover in contact with the rear prism portion is an elastic body (32) having light-shielding properties.

4. The light guide has an upper surface (2f) and a lower surface (2g) which are two surfaces connecting the incident portion, the emitting surface and the reflecting surface; the back cover forms a part of a holding body (10) for holding the light guide; the holding body further includes, in addition to the back cover, an upper cover (4) facing the upper surface and holding the upper surface, and a lower cover (5) facing the lower surface and holding the lower surface.

5. The upper cover has a recess (41) for holding the upper surface of the light guide; The lower cover has a recess (51) for holding the lower surface of the light guide.

6. Among the upper cover and the lower cover, the surface adjacent to the surface on which the recess is formed and closer to the reflecting surface than the emitting surface is defined as an end surface (4b, 5b); The back cover is attached so as to connect the upper cover and the lower cover at a position closer to the end surface than the recess of the upper cover and the lower cover.

7. The optical member according to claim 4, wherein the surfaces (4a, 5a) of the upper cover and the lower cover facing the light guide are light-shielding surfaces and rough surfaces.

8. Taking the direction perpendicular to the extending direction of the incident prism part and along the direction in which the plurality of incident prism parts are arranged as the light guiding direction (D1), The optical member according to claim 4, wherein the widths of the upper cover and the lower cover in the light guiding direction are larger than the width of the back cover in the light guiding direction.

9. Taking the surface connecting the light emitting surface, the reflecting surface, the upper surface and the lower surface of the light guide as the end surface (2e), The holding body is located on the side of the end surface and further has a rear cover (6) connecting at least the upper cover and the lower cover. The optical member according to claim 4.

10. The optical member according to claim 9, wherein the surface (6a) of the rear cover facing the light guide is a light-shielding surface and a rough surface.

11. The optical member according to claim 9, wherein the rear cover faces the end surface and has a recess (61) for holding the end surface.

12. Taking the surfaces adjacent to the surfaces of the upper cover, the lower cover and the rear cover facing the light guide and closer to the light emitting surface than the reflecting surface as the injection side surfaces (4c, 5c, 6c), The optical member according to claim 9, wherein the ends of the injection side surfaces of the upper cover, the lower cover and the rear cover have a curved shape without corners.

13. The optical member according to claim 4, wherein the light guide has protruding rib-shaped ribs (24) protruding more than the reflecting surface near the upper surface and the lower surface of the reflecting surface.

Images