JP7700733B2 - blind spot assist device - Google Patents

Description

The present invention relates to a blind spot assistance device that uses an optical member that internally reflects a portion of the light that is 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.

Conventionally, an example of this type of optical member is that described in Patent Document 1. The optical member described in Patent Document 1 is attached to a pillar of a vehicle and used as part of a blind spot assistance device. This optical member includes a half mirror that reflects part of the outside light while transmitting the other, a mirror that reflects the light reflected by the half mirror back to the half mirror, and a case body that holds these in an opposing arrangement, and the case body is attached to the vehicle pillar.

When external light enters from the opposite side of the vehicle pillar, the optical member is configured so that the external light is repeatedly reflected between a pair of mirrors consisting of a mirror and a half mirror, and then passes through the half mirror arranged on the opposite side of the vehicle pillar. This makes it possible to visually recognize the external view in the blind spot area hidden by the vehicle pillar through the optical member.

JP 2015-147496 A

However, because the mirror and the half mirror are separate components in this optical component, if their relative positions become misaligned, the position of the outside scene as seen by the light transmitted through the half mirror, i.e., the position of the outside scene as seen by the user through the optical component, will differ from the actual position. To prevent this from happening, a housing is required to hold the pair of mirrors in place so that the relative positions do not shift, and a fixing member is required to fix the housing and the pair of mirrors. Furthermore, a configuration to prevent the relative positions of the pair of mirrors from shifting requires a large number of parts, and assembly to other components such as vehicle pillars is complex and requires high precision.

After extensive research, the inventors have devised a new optical element made of a single member that uses a light-guiding material and is capable of guiding incident external light inward using total reflection, and have created a new blind spot assistance device in which this optical element is held and fixed to another member such as a vehicle pillar. Because this new blind spot assistance device is a single member in which the optical element does not have two separate mirrors, there is no misalignment in the relative positions of the pair of mirrors, and the resulting misalignment between the position of the external scene and the actual scene is suppressed.

This new blind spot assistance device requires a certain gap between the holding member and the light reflecting surface, since the optical member is configured to utilize total reflection. However, as a result of further investigation by the inventors, it was found that when external light enters the gap between the optical member and the holding member, unintended light is superimposed on the light emitted to the outside from the exit surface of the optical member.

In view of the above, the present invention aims to suppress unintended light superposition in a blind spot assistance device that uses an optical member that does not cause a relative positional misalignment between two surfaces: an exit surface that reflects and transmits incident external light, and a reflecting surface that reflects the incident external light to the exit surface.

In order to achieve the above object, the blind spot assistance device described in claim 1 has an entrance surface (2a, 23a) on which external light enters, a plurality of exit portions (21) and a plurality of flat portions (22), an exit surface (2b) on which the incident light entering from the entrance surface first arrives, and a smooth surface (2c) arranged opposite the plurality of flat portions, an optical member (2) made of a translucent material, a storage portion (31) in which the optical member is stored, a holding member (3) that holds the optical member, and a storage portion for the optical member. The surface facing the smooth surface is the bottom surface (31a), and the optical member includes a light-shielding member (4) that is disposed at least at the end of the gap between the smooth surface and the bottom surface of the housing portion on the side of the entrance surface. The flat portions are first reflecting surfaces that reflect the incident light toward the smooth surface by total reflection, and the smooth surface is a second reflecting surface that reflects the light reflected by the flat portions toward the exit surface by total reflection. The exiting portions emit a portion of the incident light or a portion of the light reflected by the smooth surface to the outside on the side opposite the holding member.

This blind spot assistance device uses an optical member that is a single member made of a translucent material, and a portion of the outside light incident from the entrance surface of the optical member is reflected by total reflection at the flat portion and the smooth surface, while a portion of the incident outside light is emitted to the outside from the exit portion. This blind spot assistance device requires fewer components than conventional devices because there is no relative positional misalignment between the flat portion and the smooth surface of the optical member that function as a pair of mirrors, and the optical member has a structure that makes it easy and simple to assemble to the holding member. In addition, a light-shielding member is placed at the end of the gap between the smooth surface of the optical member and the bottom surface of the storage section of the holding member on the entrance surface side, preventing light from entering from the entrance surface side, so that unnecessary outside light does not enter the smooth surface, and unintended outside light does not overlap with the light emitted from the exit surface.

The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below.

1 is a perspective view of a blind spot assistance device according to a first embodiment; 1 is an exploded perspective view of a blind spot assistance device according to a first embodiment; 3 corresponds to the cross-sectional view taken along line III-III in FIG. 1 and shows the arrangement of the light-shielding member and the blocking of outside light by the light-shielding member. FIG. FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. FIG. 4 is a perspective view of the optical member as viewed from a different angle. FIG. 6 is a cross-sectional view taken along the line VI-VI of FIG. 5 . FIG. 2 is an explanatory diagram for explaining light guiding in the blind spot auxiliary device of the first embodiment. 10 is an explanatory diagram for explaining superposition of emitted light and unintended external light in a blind spot compensation device of a comparative example that does not have a light blocking member. FIG. FIG. 4 is a cross-sectional view showing a blind spot assistance device according to a modified example of the first embodiment. FIG. 4 is a cross-sectional view corresponding to FIG. 3 and showing a blind spot assistance device according to a second embodiment. 13 is an explanatory diagram for explaining light guiding in a blind spot auxiliary device of a second embodiment. FIG. FIG. 5 is a cross-sectional view corresponding to FIG. 3 and showing a blind spot assistance device according to a third embodiment. FIG. 7 is a cross-sectional view corresponding to FIG. 6 and showing an optical member according to a third embodiment. FIG. 13 is an explanatory diagram for explaining light guiding in a blind spot auxiliary device according to a third embodiment. FIG. 13 is a perspective view showing an optical member according to a blind spot assistance device of a fourth embodiment. FIG. 7 is a cross-sectional view corresponding to FIG. 6 and showing an example of the configuration of another optical member. FIG. 7 is a cross-sectional view corresponding to FIG. 6 and showing an example of the configuration of another optical member. FIG. 7 is a cross-sectional view corresponding to FIG. 6 and showing an example of the configuration of another optical member. FIG. 7 is a cross-sectional view corresponding to FIG. 6 and showing an example of the configuration of another optical member.

The following describes embodiments of the present invention with reference to the drawings. In the following embodiments, parts that are identical or equivalent to each other are denoted by the same reference numerals.

First Embodiment
A blind spot assistance device 1 according to a first embodiment will be described with reference to the drawings.

In Figures 1 and 2, a portion of the invisible outer periphery of the holding member 3, which will be described later, is indicated by a dashed line. For ease of explanation, the direction of the holding member 3 along the light guide direction of the optical member 2, which will be described later, as shown in Figure 1, will be referred to as the "first direction D1," and the direction along the direction connecting the upper surface 2e and lower surface 2f of the optical member 2, which will be described later, will be referred to as the "second direction D2." D1 and D2 shown in Figures 2 and subsequent figures correspond to D1 and D2 shown in Figure 1.

The blind spot assistance device 1 of this embodiment includes an optical member 2, a holding member 3 having a storage section 31, and a light blocking member 4, as shown in FIG. 1 and FIG. 2, for example. As shown in FIG. 3 and FIG. 4, the blind spot assistance device 1 is configured such that the optical member 2 is attached to the storage section 31 of the holding member 3, and the light blocking member 4 is disposed at one end of the gap between the optical member 2 and the holding member 3. The blind spot assistance device 1 is configured to guide external light from a blind spot area by the holding member 3 inside the optical member 2 and emit it to the user side, thereby allowing the blind spot area to be viewed. The blind spot assistance device 1 is preferably applied to an in-vehicle application in which the holding member 3 is a pillar that obstructs the driver's field of vision in a vehicle such as an automobile, and allows the driver to view the blind spot area, but of course it can also be applied to blind spot assistance in other applications. In this specification, a case in which the blind spot assistance device 1 is used for an in-vehicle application will be described as a representative example.

As shown in FIG. 5, the optical member 2 is a light guide having an incident surface 2a, a smooth surface 2c adjacent to the incident surface 2a, an exit surface 2b facing the smooth surface 2c, and a terminal surface 2d facing the incident surface 2a. The optical member 2 has an upper surface 2e and a lower surface 2f that connect the exit surface 2b and the smooth surface 2c, and also connect the incident surface 2a and the terminal surface 2d. The optical member 2 is a single member whose base is made of a light-transmitting material, and in a situation where there is no incident light on the incident surface 2a, when the user looks at the optical member 2 alone from the exit surface 2b side, the user can see the scene on the smooth surface 2c side. As the light-transmitting material, for example, a resin material such as polyethylene terephthalate, polycarbonate, polyethylene, acrylic, or an inorganic material such as glass can be used. The optical element 2 does not have a mirror or a half mirror made of a reflective material with a reflectance equal to or higher than a predetermined value, and is designed to guide the incident light by total reflection on a surface made of a light-transmitting material. In this embodiment, the base of the optical element 2 refers to the portion excluding the light absorbing film 211 described later.

In this embodiment, the optical element 2 is fixed to the holding member 3 by being fitted into the housing portion 31 of the holding member 3, as shown in Fig. 4 for example. The optical element 2 is held by the holding member 3 with the smooth surface 2c facing the housing portion 31 and the exit surface 2b facing in the opposite direction to the holding member 3. The optical element 2 is fixed with a predetermined gap _D0 (for example, but not limited to, 1 mm or more) between the smooth surface 2c and the bottom surface 31a of the housing portion 31, so that the total reflection state at the smooth surface 2c can be ensured. The optical element 2 is attached to the holding member 3 so that the entrance surface 2a and the end surface 2d are located near the ends of the bottom surface 31a of the housing portion 31 in the first direction D1.

As shown in FIG. 6, for example, the optical element 2 has an exit surface 2b having a plurality of exit portions 21 and flat portions 22, which are arranged alternately and repeatedly. As shown in FIG. 7, for example, the optical element 2 allows outside light to enter the interior from the entrance surface 2a, and while repeatedly reflecting the incident light at the exit surface 2b and the smooth surface 2c, emits a portion of the light from the exit surface 2b to the outside, allowing a user standing on the exit surface 2b side to view the outside view.

7, for convenience of explanation, light from the outside of the optical member 2 to the incident surface 2a may be referred to as "external scene light _L1 ," and light of the external scene light _L1 that enters the inside of the optical member ₂ from the incident surface 2a may be referred to as "incident light _L2 ." Furthermore, light of the incident light L2 that is emitted from the exit surface 2b to the outside of the optical member 2 may be referred to as "emitted light _L3 ."

As shown in FIG. 7, for example, the optical member 2 is designed to satisfy the following formula (1) in order to totally reflect the incident light _L2 at the flat portion 22 of the exit surface 2b and the smooth surface 2c, which are made of a light-transmitting material.

sinφ≧n ₂ /n ₁ ...(1)
In formula (1), n ₁ is the refractive index of the optical member 2, and n ₂ is the refractive index of the external medium (e.g., air). φ is the angle of incidence of the incident light L ₂ to the flat portion 22, which is the angle between the normal direction (hereinafter simply referred to as the "normal direction") to the plane formed by the flat portion 22 or the smooth surface 2c and the traveling direction of the incident light L _2. As a result, the optical member 2 is configured such that a part of the incident light L ₂ from the incident surface 2a is totally reflected by the flat portion 22 and the smooth surface 2c and is emitted to the outside from the emission surface 2b, even without a semi-transparent mirror and a mirror made of a reflective material such as metal. It is preferable that the inclination angle ψ of the incident surface 2a with respect to the normal direction is smaller than the incident angle φ of the incident light L ₂ , i.e., the light guide angle. θ ₁ in FIG. 7 is the angle of incidence of the outside scene light L ₁ , which is the angle between the traveling direction of the outside scene light L ₁ and the normal direction.

The exit surface 2b is a surface where the incident light _L2 from the incident surface 2a first arrives. The exit surface 2b is, for example, a triangular protrusion in a cross-sectional view, and a plurality of similar exit portions 21 are arranged in parallel across a flat portion 22. The exit portions 21 of the exit surface 2b are portions that emit the incident light _L2 to the outside. The flat portion 22 of the exit surface 2b is a first reflecting surface that reflects the incident light _L2 toward the smooth surface 2c by total reflection. This allows the optical element 2 to guide the incident light _L2 inside without having a semi-transparent mirror made of a metal material or a dielectric material, and is configured such that no loss due to absorption of the incident light _L2 occurs in the flat portion 22.

Here, one imaginary plane formed by the flat portions 22 is a flat surface, the direction from the incident surface 2a toward the terminal surface 2d along the flat surface is a light guide direction, and the width in the light guide direction is _W22 . At this time, the flat portions 22 have a width _W22 at which the reflectance of the incident light _L2 on the exit surface 2b is equal to or greater than a predetermined value. Specifically, the flat portions 22 of the exit surface 2b are reflection portions of the incident light _L2 , and the exit portions 21 are absorption portions and exit portions of the incident light _L2 , so that the reflectance _RW of the exit surface 2b is determined by the ratio of the flat portions 22. The reflectance _RW of the exit surface 2b is expressed by the following formula (2), where _W21 is the width in the light guide direction of the exit portion 21 adjacent to the flat portion ₂₂ of width W22.

R _W = W ₂₂ / (W ₂₁ + W ₂₂ )...(2)
The flat portions 22 preferably have a width that satisfies R _W ≧0.5, that is, a width W ₂₂ at which the reflection of the incident light L ₂ at the emission surface 2b is greater than or equal to the emission, that is, W ₂₁ /W ₂₂ ≦ 1. In this case, the optical member 2 guides half or more of the incident light L ₂ at the emission surface 2b and emits the emission light L ₃ over a wider range of the emission surface 2b, making it possible to ensure the brightness of the emission light L ₃ .

Furthermore, when the optical member 2 satisfies the above formula (1) and the incident angle φ is the total reflection angle, the reflectance R _W at the exit surface 2b is determined, as shown in the above formula (2), only by the ratio of the widths of the exit portion 21 and the flat portion 22. In other words, since the reflectance R _W of the optical member 2 does not depend on the angle or wavelength of the incident light _L2 , the optical member 2 has the effect of suppressing changes in color tone and brightness of the exit light _L3 compared to conventional optical members using semi-transparent mirrors.

As shown in FIG. 7, the plurality of emission sections 21 have a first surface 21a and a second surface 21b that faces the first surface 21a and intersects with the first surface 21a. The first surface 21a is adjacent to the flat portion 22 and emits a part of the incident light _L2 to the outside. The first surface 21a is, for example, approximately parallel to the incident surface 2a. When the first surface 21a is parallel to the incident surface 2a, the emission angle θ2 of the emitted light _L3 from the first surface 21a is the same as the incident angle _{θ1 ,} so that the optical element 2 can allow a user on the side of the emission surface 2b to visually recognize the same light as the external scene light _L1 .

The emission angle _θ2 of the emitted light _L3 is the angle between the traveling direction of the emitted light _L3 and the normal direction. In addition, "substantially parallel" includes a case where the incident surface 2a and the first surface 21a are parallel, as well as a case where the incident surface 2a and the first surface 21a are approximately parallel due to unavoidable errors due to the processing accuracy of the optical member 2. The same meaning is applied to "substantially parallel" in the following specification.

The second surface 21b of the plurality of emission parts 21 is inclined at an inclination angle δ with respect to the normal direction. For example, the second surface 21b is preferably covered with a light absorbing film 211 from the viewpoint of suppressing reflection of the incident light _L2 on the second surface 21b and intrusion of external light from the emission surface 2b side. This can suppress ghosts in which the external light from the emission surface 2b side appears to overlap with the emission light _L3 , and noise caused by unintended reflected light of the incident light _L2 on the second surface 21b being emitted from the first surface 21a. The light absorbing film 211 is made of any light-shielding resin material or metal material, and is formed by any process such as printing or deposition.

The inclination angle δ of the second surface 21b is equal to _or larger than the emission angle θ2 of the emitted light _L3 , and equal to or larger than the incidence angle _θ1 of the outside light _L1 when the incidence surface 2a and the first surface 21a are parallel. As a result, the emitted light _L3 is emitted to the outside without being blocked by the second surface 21b. In addition, it is preferable that the inclination angle δ of the second surface 21b is smaller than the incidence angle φ (light guide angle) of the incident light _L2 at the flat portion 22. As a result, the incident light _L2 is prevented from being incident on the second surface 21b and interfering with it, and unintended reflection of the incident light _L2 at the second surface 21b and noise caused thereby can be suppressed.

In addition, when the width W21 of the plurality of emission portions ₂₁ and the width _W22 of the plurality of flat portions ₂₂ are all the same, a gap of width W21 is formed in the reflected light beam, and the relationship between the gap and the subsequent emission portion 21 has a periodic change, which may cause uneven brightness, i.e., moire. From the viewpoint of suppressing such moire, it is preferable that _W21 and _W22 are values within a predetermined range centered on a certain value, i.e., have a distribution.

The smooth surface 2c is a second reflecting surface that reflects the incident light _L2 reflected by the flat portion 22 toward the exit surface 2b by total reflection. In other words, the smooth surface 2c is an optical surface that is approximately parallel to the flat portion 22 and functions as a pair of mirrors together with the flat portion 22. Therefore, the incident light _L2 from the entrance surface 2a is repeatedly incident and reflected at the flat portion 22 and the smooth surface 2c at an incident angle φ, and is emitted to the outside from the exit portion 21 over the entire area of the exit surface 2b while traveling along the light guide direction. The remaining part of the incident light _L2 is finally emitted to the outside from the terminal surface 2d.

The end surface 2d is a surface connecting the exit surface 2b and the smooth surface 2c on the opposite side to the entrance surface 2a, and is located at a position opposite to the entrance surface 2a, i.e., at the end in the light guide direction. As shown in FIG. 6, for example, the end surface 2d is inclined to intersect with the first surface 21a of the exit portion 21 (hereinafter referred to as the "end exit portion") located at the end opposite to the entrance surface 2a among the multiple exit portions 21. Note that the end surface 2d is not limited to the configuration shown in FIG. 6, and may be configured to form one surface together with the first surface 21a of the end exit portion 21, or the inclination may be adjusted so as to form a curved surface continuous with the holding member 3 described later. In the former case, the end surface 2d is approximately parallel to the entrance surface 2a.

The upper surface 2e and the lower surface 2f are non-optical surfaces that are not used to reflect the incident light _L2 . The width of the optical member 2 in the direction connecting the upper surface 2e and the lower surface 2f is approximately the same as the width of the accommodation portion 31 of the holding member 3 in the second direction D2. The optical member 2 is configured so that the upper surface 2e and the lower surface 2f are fitted into the holding member 3 and fixed.

The holding member 3 is a member to which the optical member 2 is attached, and in the case of an in-vehicle application, it is, for example, a vehicle pillar such as an A-pillar, or a pillar cover that covers the vehicle pillar. The holding member 3 has a storage section 31 in which the optical member 2 is stored, as shown in FIG. 2, for example. When the optical member 2 is attached to the holding member 3, the bottom surface 31a of the storage section 31 faces the smooth surface 2c of the optical member 2, and the side wall surface 31b adjacent to the bottom surface 31a faces the upper surface 2e and the lower surface 2f of the optical member 2, respectively. In the holding member 3, a part of the side wall surface 31b protrudes outward from the bottom surface 31a in the first direction D1. The part of the side wall surface 31b that protrudes outward from the bottom surface 31a is the protruding portion 31ba, and the protruding portion 31ba covers a predetermined area of the upper surface 2e and the lower surface 2f of the optical member 2 on the incident surface 2a side.

The light blocking member 4 is disposed at least at the end of the gap between the optical member 2 and the holding member 3 on the side of the incident surface 2a, and is a member for blocking part of the gap to block light. The light blocking member 4 is made of an elastic body such as rubber, resin, or silicon. The light blocking member 4 is also a light absorber made entirely or partially of a light absorbing material. For example, it is preferable that the width of the part of the light blocking member 4 that contacts the smooth surface 2c is a predetermined width or less (for example, 1 mm or less, although this is not limited thereto) so as to minimize the interference with the internal total reflection at the smooth surface 2c.

The light shielding member 4 is bonded to the optical member 2 by an optical adhesive such as OCA or OCR (not shown), or is bonded to the holding member 3 by any adhesive, and is integrated with the optical member 2 or the holding member 3. OCA is an abbreviation for Optical Clear Adhesive, and OCR is an abbreviation for Optical Clear Resin. As shown in FIG. 3, for example, when the optical member 2 is attached to the storage section 31 of the holding member 3, the light shielding member 4 prevents unintended light _L11 from the incident surface 2a side from being incident on the smooth surface 2c while ensuring a gap of a predetermined amount or more between the smooth surface 2c and the bottom surface 31a of the storage section 31. That is, the light shielding member 4 functions as a positioning member for the holding member 3 in addition to blocking light. This ensures total reflection inside the smooth surface 2c, and prevents unintended light _L11 from being superimposed on the exit light _L3 exiting from the exit surface 2b, which interferes with the visibility of the outside view.

Specifically, as shown in FIG. 8, in the case of the blind spot assistance device 100 of the comparative example that does not have the light blocking member 4, the external scene light _L1 is incident on the incident surface 2a of the optical member 2, and the unintended light _L11 is also incident on the gap with the holding member 3. Then, the incident light _L2 and the incident unintended light _L11 enter the inside of the optical member 2, and these lights are emitted from the first surface 21a of the emission part 21. As a result, the emitted light _L3 and the unintended light _L11 are superimposed on the emission surface 2b, and the external scene is prevented from being seen on the emission surface 2b. Thus, although the blind spot assistance device 100 of the comparative example has a new configuration using the optical member 2 made of a single member, the above-mentioned superimposition of light may cause the external scene to be prevented from being seen on the emission surface 2b.

In contrast, in the blind spot assistance device 1 of the present embodiment, the light blocking member 4 is disposed at the end of the gap between the optical member 2 and the holding member 3 on the side of the entrance surface 2a, so that unintended light _L11 from the outside on the entrance surface 2a side is not incident on the smooth surface 2c. This prevents the unintended light L11 from being superimposed on the exit light _L3 from the exit surface 2b, and ensures visibility of the outside scene on the exit surface 2b.

In the blind spot assistance device 1 of the present embodiment, the optical member 2 that guides the incident light _L2 is composed of a single member, and there is no positional misalignment between the emission surface 2b that reflects the incident light _L2 and emits it to the outside, and the smooth surface 2c that reflects the incident light _L2 , i.e., the portions that function as a pair of mirrors. In addition, the blind spot assistance device 1 does not require a fixing member for suppressing the relative positional misalignment of the portions of the optical member 2 that function as a pair of mirrors, and has a smaller number of parts than the conventional device, and does not require precision in assembling to the holding member 3. Furthermore, the blind spot assistance device 1 has a gap of a predetermined amount or more between the optical member 2 and the holding member 3, and can ensure total reflection on the smooth surface 2c. In addition, the blind spot assistance device 1 prevents unintended light from entering the smooth surface 2c from the outside by the light shielding member 4, so that other unintended light is suppressed from superimposing on the emission light _L3 , and visibility of the outside scene on the emission surface 2b can be ensured.

(Modification of the first embodiment)
9, the blind spot assistance device 1 may be configured such that the light blocking member 4 is disposed on the end of the smooth surface 2c on the side of the terminal surface 2d in addition to the end of the smooth surface 2c on the side of the incident surface 2a. This prevents unintended light _L11 from the outside on the side of the terminal surface 2d from entering the smooth surface 2c of the optical member 2.

According to this modified example, in addition to the effects of the first embodiment described above, the blind spot assistance device 1 also has the effect of preventing unintended light _L11 from the outside on the terminal face 2d side from being superimposed on the emitted light _L3 , thereby further improving the visibility of the outside scene at the emission face 2b.

Second Embodiment
A blind spot assistance device 1 according to a second embodiment will be described. In Fig. 11, in order to make it easier to understand the light guide in the optical member 2 according to this embodiment, the outside light _L1 , the incident light _L2 , _L21 , _L22 , and the exit light _L3 are hatched, although a cross section is not shown.

The blind spot assistance device 1 of this embodiment differs from the first embodiment in that, as shown in FIG. 10, the entrance surface 2a of the optical member 2 protrudes beyond the smooth surface 2c in the thickness direction of the optical member 2, and part of the exit surface 2b is an exit area 2b1 composed only of the exit portion 21. This difference will be mainly described in this embodiment.

In the present embodiment, the optical member 2 has an incident surface 2a that protrudes from the smooth surface 2c in the thickness direction, and the surface of the portion of the incident surface 2a that protrudes from the smooth surface 2c is adjacent to the smooth surface 2c, forming an inclined surface 2g that is inclined toward the smooth surface 2c. In other words, the optical member 2 has a configuration in which the incident surface 2a is, so to speak, a part of one large prism portion, and has a thickness partially larger than the thickness between the smooth surface 2c and the flat portion 22. The inclined surface 2g is formed with a light absorbing film 211, for example, similar to the second surface 21b of the exit portion 21, and is a surface on which the outside scene light _L1 is not incident.

In this embodiment, the optical member 2 has a larger area of the incident surface 2a than the first embodiment, and therefore the area of the portion of the exit surface 2b where the incident light _L2 from the incident surface 2a first reaches is larger. The optical member 2 is capable of guiding more light, and is configured to have no gaps in the light guiding. The "light guiding gap" here means a gap in the light guiding direction between adjacent exit lights _L3 across an exit section 21 that does not emit light, in a state where an exit section 21 where the incident light _L2 does not reach is generated on the exit surface 2b, that is, an exit section 21 that does not emit the exit light _L3 to the outside is generated. In other words, the exit surface 2b is in a state where all of the multiple exit sections ₂₁ emit the exit light L3, and no gaps are generated in the external scene visually recognized by the user.

In the present embodiment, the optical member 2 has an emission region 2b1, which is a partial region of the emission surface 2b from the end portion on the terminal surface 2d side, that is composed of only a plurality of emission portions 21. The emission region 2b1 is a region that does not reflect the incident light _L2 reflected by the smooth surface 2c, and is a region where the emission light _L3 is mainly emitted from the first surface 21a to the outside.

11, for example, the width of the portion of the exit surface 2b where the incident light _L2 from the entrance surface 2a first reaches in the light guide direction of the optical member 2 is denoted as _La . Also, the width of the optical member 2 in the light guide direction from the end of the entrance surface 2a on the exit surface 2b side to the end of the smooth surface 2c on the terminal surface 2d side is denoted as _Lb. In this case, it is preferable that the optical member 2 is configured to satisfy the following expressions (3) and (4).

L _a = (2N-1) x T ₀ x tanφ... (3)
L _b =2N×T ₀ ×tanφ...(4)
In formulas (3) and (4), N is a positive integer. When the optical member 2 satisfies formulas (3) and (4), the end of the incident light _L2 ( _L22 in FIG. 11) that reaches the smooth surface 2c by repeated reflection at the exit surface 2b coincides with the upper end of the terminal surface 2d. As a result, the terminal surface 2d is in a state where only the light reflected at the smooth surface 2c is incident, while the light reflected at the flat portion 22 of the exit surface 2b is not incident. In other words, the light emitted from the terminal surface 2d is only emitted to the side of the exit surface 2b, and is not emitted to the side of the smooth surface 2c. Therefore, the optical member 2 can emit guided light in the user's viewing direction without waste.

In addition to satisfying the above formula, by making the portion of the emission surface 2b beyond _La into the emission region 2b1, all of the incident light _L2 that reaches the emission region 2b1 can be emitted in the user's viewing direction. In other words, the number of emission sections 21 in the portion beyond _La can be minimized, and the length of the optical member 2 in the light guide direction can be reduced.

Note that L _a may be within a range of ±10% of the value represented by (2N-1)×T ₀ ×tan φ. Also, L _b may be within a range of ±10% of the value represented by 2N×T ₀ ×tan φ. This is because a deviation of about 10% may occur due to the angle of incident light, and if L _a and L _b are within the above ranges, the effect of minimizing light guide loss is expected.

In this embodiment, the light shielding member 4 is disposed, for example, in the portion of the gap between the optical member 2 and the housing portion 31 located on the inclined surface 2g and the end portion on the terminal surface 2d side, but may be disposed only in the portion located on the inclined surface 2g. In this embodiment, the light shielding member 4 disposed in the portion located on the inclined surface 2g can prevent unintended outside light, i.e., light _L11 , from being incident on the smooth surface 2c, and can suppress the superposition of unnecessary light _L11 on the emitted light L3. In this embodiment, the "end portion on the incident surface 2a side" of the gap between the optical member 2 and the holding member 3 means an area closer to the incident surface 2a than the smooth surface 2c. In addition, the portion of the light shielding member 4 that abuts against the inclined surface 2g does not contact the smooth surface 2c, so its width is arbitrary. Furthermore, the portion of the light shielding member 4 that abuts against the inclined surface 2g only needs to be able to block unintended light _L11 from reaching the smooth surface 2c, and the arrangement and height of the inclined surface 2g in the first direction D1 can be appropriately changed.

According to this embodiment, in addition to the effects of the first embodiment, the light _L2 incident on the entrance surface 2a of the optical member 2 can be guided to the exit surface 2b and the terminal surface 2d without waste, and the blind spot assistance device 1 can obtain the effect of minimizing the loss of light rays. Furthermore, when the optical member 2 is configured to satisfy the above formulas (3) and (4), the area of the exit region 2b1 can be minimized while minimizing the loss of light rays, and the length in the light guide direction and therefore the manufacturing cost can be reduced.

Third Embodiment
A blind spot auxiliary device 1 according to a third embodiment will be described. In Fig. 14, like Fig. 11, the outside light _L1 , the incident light _L2 , and the exiting light _L3 are hatched, although the cross section is not shown.

As shown in FIG. 12, the blind spot assistance device 1 of this embodiment has an optical member 2 that has an entrance portion 2h made up of multiple prism portions 23 on the plane of the smooth surface 2c instead of the entrance surface 2a, and an entrance side surface 2i that connects the entrance portion 2h and the exit surface 2b. In this respect, the blind spot assistance device 1 differs from the first embodiment. This embodiment will mainly describe this difference.

In this embodiment, the optical element 2 has an incident portion 2h arranged on the plane of the smooth surface 2c, instead of the incident surface 2a, as shown in, for example, Figures 12 and 13. The optical element 2 further has an incident side surface 2i connecting the incident portion 2h and the exit surface 2b, and is fixed to the holding member 3 with the incident portion 2h protruding outward from the housing portion 31.

The incident portion 2h is formed by repeatedly and continuously arranging a plurality of prism portions 23 having similar shapes with the same orientation. The plurality of prism portions 23 are, for example, triangular in cross section, and one surface of the outer surface opposite to the smooth surface 2c is an incident surface 23a through which a part of the outside light _L1 is incident inside. The plurality of prism portions 23 are, for example, arranged so that the respective incident surfaces 23a are substantially parallel. The surface of the plurality of prism portions 23 facing the smooth surface 2c is an adjacent surface 23b. The inclination angle of the adjacent surface 23b of each of the plurality of prism portions 23 is set to a predetermined angle or less so as not to impede the incidence of the outside light _L1 on the incident surface 23a of the other adjacent prism portion 23.

In the incident section 2h, each of the valleys, which are the contact points between the incident surface 23a and the adjacent surface 23b of the adjacent prism section 23, is located on the plane formed by the smooth surface 2c. In other words, as shown in Fig. 14, for example, in the incident section 2h, the optical path length of the incident light _L2 from the incident surface 23a to the flat portion 22 of the exit surface 2b is substantially the same in each prism section 23. This provides the effect of minimizing distortion of the outside scene image visually recognized by the user due to the exit light _L3 exiting from the exit section 21 of the exit surface 2b, which will be described later.

The incidence side surface 2i is preferably inclined to an incidence angle φ or more of the incident light _L2 to the flat portion 22 so that the incident light _L2 is not emitted to the outside from the incidence side surface 2i.

As shown in FIG. 14 , for example, the optical member 2 is preferably designed to satisfy the following formula (5), where _T0 is the height in the normal direction between the flat portion 22 and the smooth surface 2c, and _W2a is the width of the incident portion 2h in the light guide direction.

W _2a = 2T ₀ ×tanφ...(5)
In the case of _W2a = _2T0 x tanφ, the optical member 2 is configured such that the area of the region of the emission surface 2b where the incident light _L2 from the incident portion 2h first reaches is large, while the reflected light from the region reaches only the smooth surface 2c, as shown in Fig. 14. This prevents the light guide gaps between the emission portions 21 and the flat portion 22 from occurring between the emission light L3 from the emission surface _2b , and suppresses the light loss from the incident portion 2h. Note that "light loss from the incident portion 2h" refers to the light loss caused when the incident light _L2 reflected by the flat portion 22 reaches the incident portion 2h again and is emitted to the outside from the incident portion 2h.

In addition, since a deviation of about 10% can occur due to the angle of the incident light, if W _I is within the range of the value expressed by 2T ₀ × tan φ ±10%, the optical element 2 will be configured in such a way that the above-mentioned light loss and the influence of the light guiding gaps are reduced.

In this embodiment, the light blocking member 4 is disposed, for example, at the end of the gap between the bottom surface 31a of the storage section 31 and the smooth surface 2c on the side of the entrance section 2h and the end on the side of the terminal surface 2d, but may be disposed only at the end on the side of the entrance section 2h.

In addition to the effects of the first embodiment, this embodiment provides a blind spot assistance device 1 in which the optical path lengths from the entrance surface 23a to the exit surface 2b of the multiple prism sections 23 that make up the entrance section 2h are approximately the same, minimizing distortion of the outside scene image viewed by the user at the exit surface 2b.

Fourth Embodiment
A blind spot assistance device 1 according to a fourth embodiment will be described with reference to Fig. 15. In Fig. 15, the outline of a portion of an optical member 2 is indicated by a dashed line.

The blind spot assistance device 1 of this embodiment differs from the first embodiment in that a light-shielding film 5 is formed on a portion of the upper surface 2e and the lower surface 2f of the optical member 2 that are not optical surfaces, as shown in FIG. 15, for example. This difference will be mainly described in this embodiment.

In this embodiment, the optical member 2 is covered with a light-shielding film 5 at the end regions of the upper surface 2e and the lower surface 2f on the side of the incident surface 2a and the end surface 2d. The light-shielding film 5 is a thin film of about 10 micrometers made of any light-absorbing material such as black paint, and is formed by spray coating or the like. This allows the optical member 2 to suppress unintended incidence of external light from the upper surface 2e and the lower surface 2f and unintended reflection at the upper surface 2e and the lower surface 2f inside, and is configured so that noise is not generated in the external view visible from the exit surface 2b side. The light-shielding film 5 may be formed over the entire area of the upper surface 2e and the lower surface 2f. The light-shielding film 5 may have a thickness and material that can block unintended external light that is about to enter the upper surface 2e and the lower surface 2f of the optical member 2 while not interfering with the attachment of the optical member 2 to the holding member 3, and the thickness and material may be changed as appropriate.

In addition to the effects of the first embodiment, this embodiment provides a blind spot assistance device 1 that can suppress noise caused by unintended incidence of outside light from the upper surface 2e and the lower surface 2f, and further improves visibility of the outside scene at the exit surface 2b.

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

(1) The optical member 2 may be formed to have a substantially trapezoidal shape in cross section, for example as shown in FIG. 16, except for the multiple emission sections 21 that are located at the ends on the side of the incident surface 2a. The multiple emission sections 21, except for some of the emission sections 21, do not have the first surface 21a and the second surface 21b adjacent to each other, and the tip surface thereof is a flat third surface 21c that connects the first surface 21a and the second surface 21b.

In the emission part 21 having the third surface 21c, the light absorbing film 211 is formed on the third surface 21c, not on the second surface 21b. As a result, even if the incident light L2 is incident on the second surface 21b and unintended reflection occurs, the unintended reflected light is blocked by the light absorbing film 211 formed on the third surface 21c and is not emitted to the outside from the emission surface 21b. As a result, the unintended reflected light on the second surface 21b is superimposed on the emitted light _L3 emitted to the outside from the first surface 21a, and an effect of suppressing the generation of noise is obtained.

(2) As shown in FIG. 17, the optical member 2 may have a configuration in which the emission surface 2b is divided into a plurality of regions, and the interval between the emission portions 21 varies for each divided region. In this case, for example, the emission surface 2b is divided into three regions, a first region 2ba, a second region 2bb, and a third region 2bc, along the light guide direction from the incident surface 2a side, and the interval between the emission portions 21 is made smaller in the region closer to the terminal surface 2d side. Specifically, the ratio of the width _W21 of the emission portion 21 to the width _W23 of the flat portion 22 is larger in the second region 2bb than in the first region 2ba. The third region 2bc is composed of only the emission portion 21.

More specifically, the reflectance R _W inside the exit surface 2b expressed by W ₂₂ /W ₂₁ is, for example, 2/3 in the first region 2ba, 1/2 in the second region 2bb, and 0 in the third region 2bc. In this case, assuming that the incident light L ₂ from the entrance surface 2a is 100%, the first region 2ba reflects about 67%, which corresponds to 2/3 of the incident light L ₂ , to the smooth surface 2c, and emits the remaining about 33% from the exit portion 21 to the outside. The second region 2bb reflects about 34%, which corresponds to 1/2 of the incident light L ₂ , which is about 67% reflected in the first region 2ba, to the smooth surface 2c, and emits the remaining about 33% from the exit portion 21 to the outside. The third region 2bc emits about 33% of the incident light L ₂ , which is the reflected light in the second region 2bb, to the outside from the exit portion 21. As a result, the optical member 2 has a structure in which the amount of emitted light _L3 in each of the first region 2ba to the third region 2bc is averaged to be approximately the same, and uneven brightness depending on the user's viewpoint position is reduced.

18, the optical member 2 may have the other emission portions 21, except for the emission portion 21 located on the incident surface 2a side of the first region 2ba and the emission portion 21 located in the third region 2bc located closest to the terminal surface 2d, each of which has a substantially trapezoidal shape in cross section. In this case, in addition to the effect of reducing the brightness unevenness described above, the optical member 2 can also obtain the effect of suppressing noise caused by the reflection of unintended incident light _L2 on the second surface 21b of the emission portion 21 in the first region ca and the second region 2bb.

(3) The optical member 2 may be configured, for example as shown in FIG. 19, such that the arrangement direction of the multiple prism portions 23 constituting the entrance portion 2h is the prism arrangement direction, and the prism arrangement direction is the direction connecting the exit surface 2b and the smooth surface 2c. Even in this case, the optical member 2 has a structure in which there is no relative positional deviation between the two paired reflecting surfaces, i.e., the flat portion 22 and the smooth surface 2c, and no precision is required when attaching it to the holding member 3.

(4) The optical member 2 may be configured to adopt, or freely combine, some or all of the components in the other embodiments (1) to (3) described above in the first to fourth embodiments or their modifications, except when they are clearly incompatible. For example, in the blind spot assistance device 1 of the first to fourth embodiments, the optical member 2 may have a part of the emission section 21 in a substantially trapezoidal shape, or the emission surface 2b may be partitioned into a plurality of regions, and the spacing between the emission sections 21 may be changed for each partitioned region. Also, for example, in the first to third embodiments and their modifications, the optical member 2 may be configured to have a light-shielding film 5 formed on a part or all of the upper surface 2e and the lower surface 2f. Also, for example, in the second embodiment, the optical member 2 may be configured such that the emission surface 2b does not have an emission region 2b1. In this way, the blind spot assistance device 1 may be configured to freely combine the components in each of the above embodiments and modifications within the possible range.

(5) It goes without saying that in each of the above embodiments, the elements constituting the embodiment are not necessarily essential, except when expressly stated as essential or when it is clearly considered essential in principle. Furthermore, in each of the above embodiments, when the numbers, values, amounts, ranges, etc. of the components of the embodiment are mentioned, they are not limited to the specific numbers, except when expressly stated as essential or when it is clearly limited to a specific number in principle. Furthermore, in each of the above embodiments, when the shapes, positional relationships, etc. of the components, etc. are mentioned, they are not limited to the shapes, positional relationships, etc., except when expressly stated as essential or when it is clearly limited to a specific shape, positional relationship, etc. in principle.

(Features of the present invention)
[Claim 1]
A blind spot assistance device,
an optical member (2) made of a light-transmitting material, the optical member having an entrance surface (2a, 23a) on which external scene light is incident, a plurality of exit portions (21) and a plurality of flat portions (22), an exit surface (2b) where incident light incident from the entrance surface first reaches, and a smooth surface (2c) disposed opposite the plurality of flat portions;
a holding member (3) having a storage portion (31) in which the optical member is stored and holding the optical member;
a light-shielding member (4) disposed at least at an end portion on the side of the entrance surface of a gap between a surface of the optical member including the smooth surface and the bottom surface of the storage section, the surface of the storage section facing the smooth surface of the optical member being a bottom surface (31a);
the flat portions are first reflecting surfaces that reflect the incident light toward the smooth surface by total reflection,
the smooth surface is a second reflecting surface that reflects the light reflected by the flat portion to the exit surface by total reflection,
A blind spot assistance device, wherein the plurality of emission sections emit a portion of the incident light or a portion of the light reflected by the smooth surface to the outside on the opposite side to the holding member.
[Claim 2]
The blind spot assistance device according to claim 1 , wherein the light blocking member is also disposed at an end of the gap opposite to the incident surface.
[Claim 3]
The blind spot assistance device according to claim 1 or 2, wherein the light blocking member is made of an elastic material.
[Claim 4]
4. The blind spot assistance device according to claim 1, wherein the light blocking member is made of a light absorbing material.
[Claim 5]
The blind spot assistance device according to claim 1 , wherein the light blocking member is a member integrated with the optical member or the holding member.
[Claim 6]
A blind spot assistance device as described in any one of claims 1 to 5, wherein the optical element has two opposing surfaces connecting the smooth surface and the emission surface, which are an upper surface (2e) and a lower surface (2f), and at least a portion of the upper surface or the lower surface of the optical element is covered by a light-shielding film (5).

2... Optical member, 21... Output section 21... Flat part, 2a, 23a... Incident surface,
2b...Injection surface 2b...Smooth surface, 2e...Upper surface 2e...Lower surface,
3: holding member, 31: storage section, 31a: bottom surface, 4: light shielding member,
5. Light-shielding film

Claims (6)

A blind spot assistance device,
an optical member (2) made of a light-transmitting material, the optical member having an entrance surface (2a, 23a) on which external scene light is incident, a plurality of exit portions (21) and a plurality of flat portions (22), an exit surface (2b) where incident light incident from the entrance surface first reaches, and a smooth surface (2c) disposed opposite the plurality of flat portions;
a holding member (3) having a storage portion (31) in which the optical member is stored and holding the optical member;
a light-shielding member (4) disposed at least at an end portion of a gap between the smooth surface of the optical member and the bottom surface of the housing section, the surface of the housing section facing the smooth surface of the optical member being a bottom surface (31a), the light-shielding member (4) being disposed at a side of the entrance surface of the gap between the smooth surface of the optical member and the bottom surface of the housing section,
the flat portions are first reflecting surfaces that reflect the incident light toward the smooth surface by total reflection,
the smooth surface is a second reflecting surface that reflects the light reflected by the flat portion to the exit surface by total reflection,
A blind spot assistance device, wherein the plurality of emission sections emit a portion of the incident light or a portion of the light reflected by the smooth surface to the outside on the opposite side to the holding member. The blind spot assistance device according to claim 1, wherein the light blocking member is also disposed at the end of the gap opposite the incident surface. The blind spot assistance device according to claim 2, wherein the light blocking member is made of an elastic material. The blind spot assistance device according to claim 3, wherein the light blocking member is made of a light absorbing material. The blind spot assistance device according to claim 4, wherein the light blocking member is a member integrated with the optical member or the holding member. The blind spot assistance device according to any one of claims 1 to 5, wherein the optical member has two opposing surfaces that connect the smooth surface and the emission surface, the upper surface (2e) and the lower surface (2f), and at least a portion of the upper surface or the lower surface of the optical member is covered with a light-shielding film (5).

Images