Blind spot display device

Abstract

A blind spot display device displays an image of a blind spot blocked by an obstacle (92) and includes an incident surface (2a), a light guide member (2e), a first reflecting surface (3) near a display region, a second reflecting surface (2c) near a blind spot, and a plurality of prism portions (4) protruding toward the display region. An external environmental light beam enters the incident surface, is alternately reflected on the first and second reflecting surfaces while passing through the light guide member, and is emitted toward the display region through the prism portions. The apexes of the prism portions are disposed in a three-dimensional manner rather than along a plane.

Description

Technical Field

[0001] This disclosure relates to a blind spot display device. Background Technology

[0002] Traditionally, the blind spot display device described in JP 2015-143087A displays an image of a blind spot area obscured by an obstacle. The blind spot display device includes a semi-transparent plane mirror and a plane mirror attached to the obstacle and facing each other. The device also includes a semi-transparent member disposed between the semi-transparent plane mirrors and a plurality of prisms disposed between the semi-transparent plane mirror and the viewer. Light from the blind spot area enters the semi-transparent member and travels along it, while being repeatedly reflected between the semi-transparent plane mirrors. Of the light entering the semi-transparent member, a portion travels in the viewer's direction of view after being transmitted through the plurality of prisms. With this configuration, the viewer can visually identify the image of the blind spot area. The vertices of the plurality of prisms on the viewer's side are arranged on the same plane. Summary of the Invention

[0003] This disclosure provides a blind spot display device that displays an image of a blind spot obstructed by an obstacle. The blind spot display device includes an incident surface, a light guide member, a first reflective surface near the display area, a second reflective surface near the blind spot, and a plurality of prism portions protruding toward the display area. An ambient light beam enters the incident surface, is alternately reflected on the first and second reflective surfaces while passing through the light guide member, and is emitted toward the display area through each prism portion. The vertices of each prism portion are arranged in a three-dimensional manner rather than along a plane. Attached Figure Description

[0004] The above and other objects, features, and advantages of this disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. In the drawings:

[0005] Figure 1 This is a diagram showing a view of the first embodiment from the driver's seat in the direction toward the front pillar of the vehicle;

[0006] Figure 2 This is a cross-sectional view of the blind spot display device;

[0007] Figure 3 It is shown in Figure 2 A diagram showing the path of the external environmental beam on the cross-section shown;

[0008] Figure 4 Is Figure 2 Enlarged view of the exit surface on the cross-section shown;

[0009] Figure 5 Is Figure 2 An enlarged view of the external environment beam path on the cross-section shown;

[0010] Figure 6 Is Figure 2 Enlarged view of the inclined portion of the exit surface and the periphery of the exit surface on the cross-section shown;

[0011] Figure 7 This is a diagram showing a cross-section of the blind spot display device according to the second embodiment and the external environment beam path;

[0012] Figure 8 This is a diagram showing a comparison between the first embodiment and the second embodiment;

[0013] Figure 9 The blind spot display device according to the third embodiment is in Figure 2 Cross-sectional views of the same cross section shown;

[0014] Figure 10 It is shown Figure 9 A diagram of the external environment beam path on the cross-section shown;

[0015] Figure 11 It is an explanatory diagram used to illustrate the relationship between the angle of the inclined plane and the gap between the beams;

[0016] Figure 12 This diagram illustrates how adjusting the angle of the inclined plane can suppress the gap between beams.

[0017] Figure 13 The blind spot display device according to the fourth embodiment is in Figure 9 Cross-sectional views of the same cross section shown;

[0018] Figure 14 It is an explanatory diagram used to illustrate the relationship between the width of the incident surface and the gap between the beams;

[0019] Figure 15 It is an explanatory diagram used to illustrate the relationship between the width of the incident surface and the gap between the beams;

[0020] Figure 16 This is an explanatory diagram illustrating the relationship between the width of the incident surface and the gap between the beams; and

[0021] Figure 17 It is a view showing the driver's seat as the point of view in the direction of the vehicle's front pillar. Detailed Implementation

[0022] According to the inventors' research, in some cases, the blind spot display device viewed by the viewer is attached to the curved surface of an obstacle. When the blind spot display device disclosed in JP 2015-143087 A is attached to a curved surface, the shape of the display surface of the blind spot display device viewed from the user's viewpoint is significantly different from the shape of the obstacle viewed from the user's viewpoint. This difference in appearance between the display device and the obstacle may reduce the design appeal of the display device.

[0023] One object of this disclosure is to provide a blind spot display device wherein the display surface is configured to have a curved shape when viewed from a viewpoint.

[0024] According to one aspect of this disclosure, a blind spot display device displays an image of a blind spot obstructed by an obstacle. The blind spot display device includes an incident surface, a light guide member, a first reflecting surface, a second reflecting surface, and a plurality of prisms. An ambient light beam transmitted from the blind spot enters the incident surface. The light guide member guides the ambient light beam entering through the incident surface. The first reflecting surface is disposed opposite to the blind spot relative to the light guide member. The ambient light beam guided by the light guide member is reflected on the first reflecting surface. The second reflecting surface is disposed near the blind spot relative to the light guide member. The second reflecting surface is opposite to the first reflecting surface. The ambient light beam guided by the light guide member is reflected on the second reflecting surface. The prisms are disposed opposite to the blind spot relative to the light guide member and protrude toward a display area. The display area is defined as the area opposite to the blind spot relative to the light guide member. The ambient light beam is emitted toward the display area through the prisms after traveling through the light guide member. The ambient light beam enters the light guide member through the incident surface and is then alternately reflected on the first and second reflecting surfaces while traveling in an arrangement direction away from the incident surface by the plurality of prisms. A portion of the external ambient light beam is emitted toward the display area through the plurality of prisms. The vertices of the plurality of prisms are arranged in a three-dimensional manner rather than along a plane.

[0025] In the above configuration, the vertices of each prism are arranged in a three-dimensional manner, rather than along a plane. Therefore, the display surface of the blind spot display device is configured to have a curved shape.

[0026] In the following description, embodiments of the present disclosure will be illustrated with reference to the accompanying drawings. In the following embodiments, components that are identical or equivalent to those described in the foregoing embodiments will be denoted by the same reference numerals, and their description may be omitted. In the following embodiments, when only a portion of the configuration is described in one embodiment, the remaining configurations may employ the same configuration as those described in the preceding embodiments. The various embodiments described herein can be combined in part with each other, provided there are no technical contradictions, although these combinations are not explicitly described.

[0027] (First Embodiment)

[0028] The following is for reference Figures 1-6 The first embodiment is described. (As...) Figure 1 As shown, the blind spot display device 1 of this embodiment is attached to the front pillar 92 located near the driver's seat of the vehicle. The front pillar 92 is located between the side window 93 and the windshield 94 near the driver's seat of the vehicle, and the bottom of the front pillar is connected to the instrument panel 95 of the vehicle.

[0029] The blind spot display device 1 displays an image of the blind spot area blocked by the front pillar 92. For example, as Figure 1 As shown, even if part of the pedestrian 96 enters the blind spot area, the pedestrian can still be seen through the blind spot display device 1.

[0030] The blind spot area blocked by the front pillar 92 refers to the area of ​​the vehicle's exterior hidden behind the front pillar 92 from the viewpoint of an occupant sitting in the driver's seat. The front pillar 92 is a component that ensures the rigidity of the vehicle, but it also corresponds to an obstacle that causes this blind spot area.

[0031] The blind spot display device 1 is provided by optical components. For example... Figure 2 As shown, the blind spot display device 1 includes an incident surface 2a, an exit surface 2b different from the incident surface 2a, and a planar reflecting surface 2c facing the exit surface 2b. Since the reflecting surface 2c is located on the blind spot side, it is also called the blind spot-side reflecting surface. The blind spot-side reflecting surface 2c corresponds to the second reflecting surface. Figure 2 This is a cross-sectional view of the blind spot display device 1 taken along a cross section perpendicular to the vertical direction of the vehicle. In the following description, the term "cross section" refers to a cross section perpendicular to the vertical direction of the vehicle. The cross-sectional shape of the blind spot display device 1 may be the same at any location in the vertical direction of the vehicle, or it may vary depending on its position in the vertical direction of the vehicle.

[0032] The blind spot display device 1 includes an end face 2d arranged furthest from the incident surface 2a. The end face 2d connects the exit surface 2b and the blind spot side reflective surface 2c. The blind spot display device 1 also includes a translucent light guide member 2e surrounded by the incident surface 2a, the exit surface 2b, the blind spot side reflective surface 2c, and the end face 2d. The incident surface 2a, the exit surface 2b, the blind spot side reflective surface 2c, and the end face 2d also correspond to the respective surfaces of the light guide member 2e.

[0033] The exit surface 2b is located on the opposite side of the blind-side reflective surface 2c relative to the light guide member 2e. The light guide member 2e includes a plurality of display-side reflective surfaces 3 and a plurality of prism portions 4. The plurality of prism portions 4 are arranged side by side along the exit surface 2b in the direction from the incident surface 2a to the end face 2d. The display-side reflective surfaces 3 are arranged separately from each other, and each display-side reflective surface 3 is disposed between two prism portions 4. Each display-side reflective surface 3 arranged separately from each other is provided by a flat portion 3a that is flat and parallel to each other. The display-side reflective surface 3 corresponds to the first reflective surface. Figure 2The cross-section shown includes an incident surface 2a, an exit surface 2b, a blind-side reflective surface 2c, an end face 2d, and a light guide component 2e.

[0034] like Figure 3 As shown, in the blind spot display device 1, ambient light beams L1, L2, and L3 are incident from the blind spot region onto the incident surface 2a. After entering the incident surface 2a, the beams are guided by the light guide member 2e and transmitted through it. Each beam is alternately reflected on the display-side reflecting surface 3 and the blind spot-side reflecting surface 2c. During repeated reflections, the beams move away from the incident surface 2a in the arrangement direction of the multiple prisms 4, and a portion of the ambient light beam gradually passes through the prisms 4 towards the display side. The display side is also referred to as the display area, and represents the area opposite to the blind spot relative to the light guide member 2e. That is, the display side faces the driver's field of vision as the observer. A portion of the ambient light beam from the blind spot region enters the incident surface 2a, passes through the light guide member 2e, and exits the blind spot display device 1 from the end face 2d. The ambient light beams L1, L2, and L3 are reflected on the display-side reflecting surface 3 and the blind spot-side reflecting surface 2c. Figure 3 They travel parallel to each other in the cross-section shown.

[0035] The light guide component 2e is made of a resin material such as polyethylene terephthalate, polycarbonate, polyethylene, or acrylic resin, or a light-transmitting material such as glass. The light guide component is designed such that external ambient light beams L1, L2, and L3 are totally internally reflected at the display-side reflective surface 3 and the blind-side reflective surface 2c, thereby being guided within the light guide component. Specifically, the light guide component 2e has a refractive index n1 defined by the corresponding material, and the external medium outside the light guide component 2e has a refractive index n2. The angle of incidence of each external ambient light beam L1, L2, and L3 at the display-side reflective surface 3 and the blind-side reflective surface 2c is defined as Φ. Furthermore, when the external medium is air, the refractive index n2 = 1.

[0036] The light guide component satisfies the following numerical expression (1).

[0037] sinΦ≥n2 / n1 (1)

[0038] As a result, even when the blind spot display device 1 does not have a semi-transparent mirror, a portion of the external ambient light beams L1, L2, and L3 entering the incident surface 2a are totally reflected on the flat portion 3a of the display-side reflective surface 3 and the blind spot-side reflective surface 2c, and exit from the exit surface 2b.

[0039] For example, such as Figure 3As shown, each external ambient light beam L1, L2, L3 enters the incident surface 2a of the blind spot display device 1 at an incident angle θ1 and is refracted on the incident surface 2a. Then, each beam reaches the exit surface 2b. The external ambient light beams L2 and L3 reach the respective flat portions 3a of the display-side reflective surface 3 at the same light-guiding angle Φ and are totally reflected at the boundary plane between the light guide member and the outer side. Therefore, the external ambient light beams L2 and L3 are guided in the light guide member 2e toward the blind spot side reflective surface 2c and do not exit from the light guide member 2e. The external ambient light beam L2, which reaches the blind spot side reflective surface 2c at a light-guiding angle Φ, is again totally reflected on the blind spot side reflective surface 2c and guided in the light guide member 2e toward the exit surface 2b. The blind spot side reflective surface 2c also corresponds to the boundary plane between the light guide member and the outer side. A portion of the beam is refracted by the transmission surface 4a of a prism portion 4 and exits from the prism portion at an exit angle θ2, while the remaining portion of the beam is totally reflected by the flat portion 3a.

[0040] For example, Figure 3 As shown, when the ambient light beam L2 enters from the incident surface 2a, a portion of the beam reaches the transmission surface 4a of the prism section 4 and is refracted at the boundary, thus exiting to the outside at an exit angle of θ2. Even after repeated reflections on the flat portion 3a and the blind spot side reflecting surface 2c, the ambient light beam L3 does not reach the prism section 4. The ambient light beam L3 eventually reaches the end face 2d and is emitted to the outside as afterglow. As described above, each ambient light beam L1, L2 is alternately reflected on the display side reflecting surface 3 and the blind spot side reflecting surface 2c. During repeated reflections, the beam moves away from the incident surface 2a along the arrangement direction of the multiple prisms 4, and a portion of the ambient light beam gradually passes through the prisms 4 towards the display side. As a result, the observation area on the exit surface 2b side—that is, the area where the driver can visually recognize the ambient light beam emitted from the blind spot display device—can be widened. The driver corresponds to the user of the blind spot display device.

[0041] The incident angle θ1 refers to the angle between the normal direction of the plurality of flat portions 3a perpendicular to the exit surface 2b (hereinafter referred to as the flat portion normal direction) and the incident direction of each external environment beam L1, L2, L3 incident on the incident surface 2a. The guide angle Φ refers to the angle between the travel direction of each external environment beam L1, L2, L3 and the flat portion normal direction. The guide angle Φ also refers to the angle between the travel direction of each external environment beam L2, L3 relative to the blind-side reflecting surface 2c and its normal direction relative to the blind-side reflecting surface 2c. When the flat portion 3a is parallel to the blind-side reflecting surface 2c, the guide angle Φ on the flat portion 3a and the blind-side reflecting surface 2c has the same value, regardless of reflection count. The exit angle θ2 refers to the angle between the travel direction of the external environment beams L1, L2 emitted from the exit surface 2b and the flat portion normal direction. When the incident surface 2a is parallel to the transmission surface 4a of the prism section 4, the exit angle θ2 has the same value as the incident angle θ1. The orientation of the blind spot display device 1 is determined such that the normal direction of the flat portion and the normal direction of the incident surface 2a are parallel to the horizontal plane of the vehicle. As another example, the normal direction of the flat portion and the normal direction of the incident surface 2a can be tilted relative to the horizontal plane of the vehicle.

[0042] The external ambient beams L1, L2, and L3 are merely examples of external ambient beams transmitted from the blind spot region and entering the incident surface 2a. Some of the external ambient beams transmitted from the blind spot region and entering the incident surface 2a may have different incident angles θ1 and guide angles Φ than those of the aforementioned external ambient beams L1, L2, and L2. Some or all of the external ambient beams exiting from each transmission surface 4a reach the driver's eyelid EL. The external ambient beams as a whole are incident on the incident surface 2a at an incident angle θ1 of a certain width, and are totally internally reflected at the flat portion 3a and the blind spot side reflecting surface 2c at the guide angle Φ of the same width. The beams then exit from the transmission surface 4a toward the display side, and the exiting beams cover the entire field of vision of the eyelid EL.

[0043] The light guide angle Φ can be set based on, for example, the light guide angle corresponding to the maximum incident angle of the external ambient beam incident on the light guide member 2e. The maximum incident angle of the external ambient beam can be set to... Figure 3The angle between the normal direction of the flat portion shown and the virtual straight line extending from the center of the eyelid EL to the endpoint on the exit surface 2b side of the incident surface 2a. This is because an external environment beam with an incident angle equal to or greater than the maximum incident angle is transmitted from the area visible to the user. Optionally, at least a portion of the external environment beam can satisfy the guide angle Φ defined by the numerical expression (1) above. The portion of the external environment beam can include the entire external environment beam reaching the eyelid EL. When the eyelid EL cannot be defined, the portion of the external environment beam can be set without considering the eyelid. These apply to all relational expressions including Φ, θ1, and θ2, which will be described later.

[0044] In this embodiment, the incident surface 2a and the exit surface 2b of the external ambient light beam intersect. The incident surface 2a is inclined at an angle ψ relative to the normal direction of the flat portion. That is, in this embodiment, the incident surface 2a is inclined toward the flat portion such that the angle between the incident surface and the flat portion 3a is an acute angle. The incident surface 2a has an angle ψ relative to the normal direction of the flat portion. For example, as Figure 3 As shown, the tilt angle ψ can be set to be smaller than the guide angle Φ formed between (i) the direction of travel of the external ambient beams L1, L2, L3 after entering the incident surface 2a and (ii) the flat portion 3a or the blind-side reflecting surface 2c. In this case, based on the refraction condition ψ < π / 2 - Φ, the external ambient beams L1, L2, L3 are refracted in a certain direction so that the guide angle Φ is greater than the incident angle θ1 of the external ambient beams L2, L2, and L3. In this case, the external ambient beams can be guided towards a relatively wide range toward the exit surface 2b. The guide angle Φ is set under total internal reflection conditions, and the refractive index of the ordinary translucent resin material is 1.4 or greater. Therefore, n × sinΦ > 1, and thus Φ > 45.3 degrees. Therefore, the light guide member 2e has a structure that satisfies Φ > ψ.

[0045] The exit surface 2b includes a display-side reflecting surface 3, and the display-side reflecting surface 3 includes multiple flat portions 3a and multiple prism portions 4. The exit surface 2b has a stepped shape throughout. The stepped shape is a shape that includes multiple steps. Each of the multiple steps is called a display-side step and corresponds to a first step.

[0046] like Figure 2 and Figure 3 As shown, each display-side step 21 to 27 protrudes from the blind-spot-side reflective surface 2c toward the display side, and the positional form of each display-side step protruding from the blind-spot-side reflective surface is different from each other. In this embodiment, the distance from the blind-spot-side reflective surface 2c to the end of each display-side step along the protrusion direction is different from each other. The display side is the opposite side to the blind-spot side relative to the blind-spot-side reflective surface 2c where the blind spot is located. In this embodiment, the protrusion direction is parallel to the normal direction of the flat portion. In another example, the protrusion direction can be set to be non-parallel to the normal direction of the flat portion.

[0047] The longitudinal direction of each display-side step intersects the vertical direction of the vehicle, the direction from the incident surface 2a to the end face 2d, and the normal direction of the flat portion. The longitudinal direction of each display-side step is the direction in which the steps maintain the same orientation, that is, the direction that intersects with the arrangement direction of the multiple display-side steps. The multiple display-side steps 21 to 27 are arranged from the incident surface 2a toward the end face 2d.

[0048] On the exit surface 2b, a plurality of display-side steps 21 to 27 are arranged in a direction from the side closer to the incident surface 2a to the side farther away from the incident surface 2a. The exit surface 2b has inclined surfaces 21W, 22W, 23W, 24E, 25E, and 26E, each inclined surface being arranged between two adjacent display-side steps 21 to 27.

[0049] The display side step 22 protrudes further towards the display side than the display side step 21, the display side step 23 protrudes further towards the display side than the display side step 22, the display side step 24 protrudes further towards the display side than the display side step 23, the display side step 26 protrudes further towards the display side than the display side step 27, the display side step 25 protrudes further towards the display side than the display side step 26, and the display side step 24 protrudes further than the display side step 25.

[0050] Inclined surface 21W connects display-side step 21 and display-side step 22. Inclined surface 22W connects display-side step 22 and display-side step 23. Inclined surface 23W connects display-side step 23 and display-side step 24. Inclined surfaces 21W, 22W, and 23W are arranged facing the incident surface 2a instead of the end face 2d. That is, inclined surfaces 21W, 22W, and 23W are arranged towards the windshield 94. Inclined surface 24E connects display-side step 24 and display-side step 25. Inclined surface 25E connects display-side step 25 and display-side step 26. Inclined surface 26E connects display-side step 26 and display-side step 27. Inclined surfaces 24E, 25E, and 26E are arranged facing the end face 2d instead of the incident surface 2a. That is, inclined surfaces 24E, 25E, and 26E are arranged towards the eyelid.

[0051] Each display-side step 21 to 27 includes a plurality of flat portions 3a and a plurality of prism portions 4, wherein in each display-side step, the plurality of prism portions 4 and the plurality of flat portions 3a are arranged alternately from the incident surface 2a to the end face 2d. In each display-side step, the plurality of flat portions 3a are arranged at the same position along the protrusion direction of the display-side step. In the protrusion direction of the display-side step, the position of the plurality of flat portions 3a in one display-side step differs from the position of the plurality of flat portions 3a in another display-side step. In the protrusion direction of the display-side step, the position of the prism portions 4 in one display-side step differs from the position of the prism portions 4 in another display-side step.

[0052] Multiple display-side steps 21 to 27 and ramps 21W, 22W, 23W, 24E, 25E, and 26E constitute a virtual pseudo-surface 2f. The pseudo-surface has a non-planar three-dimensional shape substantially along the vertex positions of the multiple transmission surfaces 4a. The pseudo-surface 2f is smoothly set along the contour of the front pillar 92 to which the blind spot display device 1 is attached. With the blind spot display device 1 attached to the front pillar 92, the shape of the blind spot display device 1 on the display side is perceived by occupants in the vehicle as a pseudo-surface 2f smoothly set along the front pillar 92. Therefore, the visual design effect of the blind spot display device 1 can be improved.

[0053] In each display-side step 21 to 27, the ambient light beam is partially or completely reflected by the flat portion 3a included in the display-side step. In each display-side step 21 to 27, the ambient light beam is partially or completely transmitted through the transmission surface 4a of the prism portion 4 included in the display-side step, and then the beam is emitted toward the display side.

[0054] In this embodiment, the prism portion 4 is arranged at the intersection of the incident surface 2a and the display side step 21. The exit surface 2b can be formed by, for example, a known plastic molding method using a mold.

[0055] End face 2d connects exit surface 2b and blind-side reflector 2c on the opposite side of incident surface 2a. For example, the end face can be an inclined plane tilted at a predetermined angle relative to the blind-side reflector. A portion of the ambient light beam is repeatedly reflected by display-side reflector 3 and blind-side reflector 2c, ultimately failing to reach prism section 4. These ambient light beams are emitted outward from end face 2d as afterglow. Afterglow emission can be prevented by applying a light-shielding treatment, for example, by providing a light-absorbing film (not shown) on end face 2d. Therefore, ghosting caused by afterglow leakage can be suppressed.

[0056] like Figure 3 As shown, multiple flat portions 3a in each display-side step act as reflective surfaces, which totally reflect ambient light beams reaching the flat portions 3a towards the blind-side reflective surface 2c. Therefore, the light guide member 2e can guide ambient light beams within the light guide member without the need for a translucent mirror made of metallic or dielectric materials. Furthermore, losses caused by the absorption of ambient light beams by the flat portions 3a can be limited.

[0057] like Figure 4As shown, each flat portion 3a has a width Ws along the light guiding direction, in which the light beam is guided from the incident surface 2a toward the end surface 2d along the flat portion. The width Ws of each flat portion 3a is set such that the reflectivity of the external ambient light beam on the exit surface 2b is equal to or higher than a predetermined value. Specifically, in each display side step, multiple flat portions 3a reflect the external ambient light beam, and multiple prism portions 4 absorb and emit the external ambient light beam. Therefore, the reflectivity Rw of the exit surface 2b is determined by the proportion of the flat portions 3a. The reflectivity Rw of the exit surface 2b is represented by the following numerical expression (2), where Wp represents the width of the prism portion 4 in the light guiding direction. As described above, the prism portion 4 with a width of Wp is adjacent to the flat portion 3a with a width of Ws.

[0058] Rw=Ws / (Wp+Ws) (2)

[0059] Multiple flat portions 3a satisfy Rw ≥ 0.5. That is, the width Ws of the flat portion is set such that the reflection of the external ambient light beam on the emission surface 2b is equal to or greater than the emission of the external ambient light beam. Therefore, the widths Wp and Ws satisfy the relationship Wp / Ws ≤ 1. In the above-described configuration of the blind spot display device 1, half or more of the external ambient light beam is reflected on the emission surface 2b and guided in a direction away from the incident surface 2a. Therefore, the external ambient light beam can be emitted from a wider range of the emission surface 2b, and the brightness of the external ambient light beam emitted to the display side through the emission surface 2b can be ensured.

[0060] When the above numerical expression (1) is satisfied and the light guide angle φ is the reflection angle, as shown in numerical expression (2), the reflectivity Rw of the exit surface 2b is defined only by the width ratio of the flat portion 3a to the prism portion 4. In other words, the reflectivity Rw does not depend on the incident angle or wavelength of the external ambient light beam incident on the incident surface 2a. Therefore, compared with conventional optical components using a semi-transparent mirror, the changes in the color and brightness of the external ambient light beam transmitted through the prism portion 4 and emitted outward are suppressed.

[0061] In the exit surface 2b, each prism portion 4 is disposed adjacent to the flat portion 3a and protrudes towards the display side relative to the flat portion 3a. Each prism portion 4 has a transmission surface 4a, which emits a portion of the external ambient light beam passing through the light guide member 2e outward. Each prism portion 4 also has a facing surface 4b that faces the transmission surface 4a and intersects with the transmission surface 4b. In each prism portion 4, the transmission surface 4a is disposed on the end face 2d side, and the facing surface 4b is disposed on the incident surface 2a side. In each prism portion 4, the transmission surface 4a intersects with the facing surface 4b at the apex of the prism portion 4 in the protruding direction. The cross-sectional shapes of the plurality of prism portions 4 are similar to each other. The dimensions of all prism portions 4 may be the same or different.

[0062] In the protruding direction of each display-side step 21 to 27, the position of the flat portion 3a in one display-side step differs from the position of the flat portion in another display-side step. Similarly, in the protruding direction of each display-side step 21 to 27, the vertex position of the prism portion 4 in one display-side step differs from the vertex position of the prism portion in another display-side step. Therefore, the vertex positions of the multiple prism portions 4 are set in a three-dimensional manner, not along a plane. Note that the term "not along a plane" excludes cases where the setting deviates from a planar setting due to unavoidable manufacturing errors. For example, the term "not along a plane" means that when the shortest vertex distance from the vertex position of each prism portion 4 to a certain reference plane P is d, the reference plane is defined such that the sum of the shortest vertex distances d of all prism portions 4 is minimized. In this case, when the average of the shortest distances d of all prism portions 4 is 3% or more of the longest vertex distance X of a prism portion, the vertices of the prism portions 4 are considered to be set in a three-dimensional manner rather than as a whole along a plane. Here, the longest vertex distance X is the distance between the two vertices of all prism portions 4 that are farthest from each other.

[0063] In each display-side step, as described above, the position of the flat portion 3a in the protruding direction differs from that in the other display-side step. Therefore, the flat portion 3a is positioned in a three-dimensional manner in the protruding direction, rather than being arranged as a whole along a plane. Here, the term "not along a plane" has the same meaning as the prism portion 4.

[0064] Each transmission surface 4a is parallel to the incident surface 2a. When the transmission surface 4a is parallel to the incident surface 2a, the exit angle θ2 of each external ambient light beam L1, L2, L3 emitted from the transmission surface 4b is the same as the incident angle θ1. Therefore, through the blind spot display device 1, the user can visually identify the same light beam as the external ambient light beam L1 on the exit surface 2b side. As described above, the incident surface 2a is parallel to the transmission surface 4a. The term "parallel" includes the case where the incident surface 2a is approximately parallel to the transmission surface 4a, taking into account the unavoidable errors due to the manufacturing precision of the light guide member 2e. This also applies to the term "parallel" in the following description of this disclosure.

[0065] For example, such as Figure 4As shown, the opposing surfaces 4b of each prism portion 4 are angled with the normal direction of the flat portion at an angle δ and intersect the transmission surface 4a. Each opposing surface 4b is covered by a light-absorbing film (not shown). The light-absorbing film suppresses the reflection of external ambient light beams passing through the light guide member 2e on the opposing surfaces 4b and the entry of external ambient light beams from the exit surface 2b. Therefore, it is possible to suppress ghosting that occurs when the external ambient light beam emitted from the transmission surface 4a to the display side overlaps with the external ambient light beam present on the display side. Furthermore, it can suppress unintentional reflection of external ambient light beams passing through the light guide member 2e on the opposing surfaces 4b and noise caused by the emission of external ambient light beams from the transmission surface 4a. The light-absorbing film can be made of any light-shielding resin material or light-shielding metal material and can be arranged on the opposing surfaces by appropriate processing (e.g., printing or vapor deposition).

[0066] The opposing surface 4b has a tilt angle δ equal to or greater than the exit angle θ2. The exit angle θ2 is the angle at which the external ambient light beam is emitted from each transmission surface 4a. When the incident surface 2a is parallel to the transmission surface 4a, the tilt angle δ is equal to or greater than the incident angle θ1 of the external ambient light beam L1. Therefore, the external ambient light beam emitted from each transmission surface 4a is emitted outward without being blocked by the opposing surface 4b. The tilt angle δ of each opposing surface 4b can be set to be smaller than the light guide angle Φ set relative to the adjacent flat portion 3a. With this configuration, interference caused by the external ambient light beam incident on the opposing surface 4b during its travel in the light guide member 2e can be suppressed. Therefore, the possibility of unintended reflection of the external ambient light beam on the opposing surface 4b during its travel in the light guide member 2e can be suppressed, and noise caused by such unintended reflection can be suppressed.

[0067] When the width Ws of each flat portion 3a is the same as the width Wp of each prism portion 4, the reflected beam includes a gap corresponding to the width Wp of the prism portion. The relationship between the gap included in the reflected beam and the prism portion 4 in the subsequent stage varies periodically, and this variation causes uneven brightness, which is called a moiré pattern. From the viewpoint of suppressing this moiré pattern, Ws and Wp can be set to a predetermined ratio instead of being the same value.

[0068] For example, in the blind spot display device 1, the value obtained by dividing the standard deviation of the width Ws of all flat portions 3a by the average width Ws of all flat portions 3a can be set within a predetermined range. The lower limit of the predetermined range can be 0.2, 0.3, 0.5, or 1.2. The upper limit of the predetermined range can be 0.5, 0.8, 1.0, 1.5, or 2.0. Note that the width Ws of all flat portions 3a can be set within ±10% of the average value.

[0069] For example, in the blind spot display device 1, the value obtained by dividing the standard deviation of the width Wp of all prism sections 4 by the average width Wp of all prism sections 4 can be set within a predetermined range. The lower limit of the predetermined range can be 0.2, 0.3, 0.5, or 1.2. The upper limit of the predetermined range can be 0.5, 0.8, 1.0, 1.5, or 2.0. Note that the width Wp of all prism sections 4 can be set within ±10% of the average value.

[0070] The values ​​of widths Ws and Wp are distributed as described above. Therefore, the periodic relationship between the gap included in the external ambient beam reflected on the flat portion 3a and the subsequent prism portion 4 can be avoided, thereby suppressing the occurrence of moiré patterns.

[0071] On the exit surface 2b, the external ambient light beam exits only from the transmission surface 4a of the prism section 4 at an exit angle θ2. Therefore, as... Figure 5 As shown by the dashed line portion, the ambient light beam reaching the user has a pattern of bright and dark, and its period width is equal to the sum of the width Ws of the flat portion 3a and the width Wp of the prism portion 4. The pitch Pe of the ambient light beam with the eyelid EL center as the viewpoint is represented by the following numerical expression (3).

[0072] Pe=(Wp+Ws)×cosθ2 (3)

[0073] The widths Ws of the adjacent flat portions 3a and the widths Wp of the prism portions 4 can be designed such that the pitch Pe of the ambient light beam emitted toward the display side is less than 2 mm. This is because in bright environments, the minimum pupil diameter of a person is equal to or greater than 2 mm. By setting the pitch Pe of the emitted ambient light beam to less than 2 mm, the amount of ambient light beam perceived by the user's vision is averaged, and brightness variations caused by viewpoint movement can be suppressed.

[0074] It should be noted that the multiple flat portions 3a may not be completely parallel to the blind spot side reflective surface 2c. The multiple flat portions 3a may be arranged non-parallel to the blind spot side reflective surface 2c, corresponding to the distance of the blind spot area that the user wants to visually identify.

[0075] When the multiple flat portions 3a are parallel to the blind spot-side reflective surface 2c, the light guiding angle Φ has a constant value, regardless of their position within the light guiding member 2e. Therefore, the exit angle θ2 of the emitted ambient light beam also has a constant value. Despite different user viewpoints, ambient light beams with the same exit angle θ2 enter the user's eye. Thus, the aforementioned state is identical to the state where a light beam emitted from infinity enters the user's eye. That is, when the blind spot area to be visually identified by the user is located at a predetermined distance from the user or longer (e.g., tens to hundreds of meters), the multiple flat portions 3a can preferably be parallel to the blind spot-side reflective surface 2c.

[0076] When the plurality of flat portions 3a are slightly angled to the blind spot-side reflector 2c, the light guiding angle Φ changes depending on the position within the light guiding member 2e. Therefore, the exit angle θ2 of the emitted ambient light beam varies depending on the user's viewpoint. This state is equivalent to a light beam entering the user's eye from a finite distance equal to or less than a predetermined value (e.g., a few meters to tens of meters). That is, when the blind spot area to be visually identified by the user is located at a predetermined distance or less from the user, the plurality of flat portions 3a can preferably not be parallel to the blind spot-side reflector 2c. In this case, the plurality of flat portions 3a and the blind spot-side reflector 2c can be arranged such that the distance between them increases in a direction away from the incident surface 2a. In other words, the plurality of flat portions 3a and the blind spot-side reflector 2c can be arranged to have an open shape in a direction away from the incident surface 2a. When multiple flat sections 3a and blind-side reflective surfaces 2c are arranged in a closed shape in a direction away from the incident surface 2a, the ambient light beam emitted from the device travels in scattering directions that are far apart from each other, and the emitted light beam cannot be focused as an image in the human eye.

[0077] According to this embodiment, the exit surface 2b, where the ambient light beam incident from the incident surface 2a first reaches, includes a display-side reflecting surface 3 composed of multiple flat portions 3a and multiple prism portions 4. Therefore, even without using a translucent mirror, the ambient light beam can be guided by the display-side reflecting surface. Thus, compared to the manufacturing process and cost of conventional optical components including translucent mirrors, the manufacturing process can be simplified and manufacturing costs reduced. In the blind spot display device 1, the ambient light beam is totally reflected by the flat portion 3a and the blind spot-side reflecting surface 2c opposite to the flat portion 3a. Therefore, light absorption loss in the light guide member 2e can be suppressed. The reflectivity Rw of the ambient light beam on the exit surface 2b is determined by the ratio between the width Ws of the adjacent flat portions 3a and the width Wp of the prism portions 4. Therefore, the reflectivity Rw does not depend on the wavelength or angle of the ambient light beam. Therefore, while suppressing light absorption loss in the light guide member 2e, changes in the brightness and hue of the ambient environment as perceived by the user through the exit surface 2b can also be suppressed.

[0078] The inclined surfaces 24E, 25E, and 26E will be described below. Each inclined surface 24E, 25E, and 26E is parallel to some or all of the transmissive surfaces 4a in an adjacent display-side step (i.e., a predetermined step) located near the incident surface 2a relative to the inclined surface. Among the multiple transmissive surfaces 4a in the adjacent display-side steps 24, 25, and 26 located near the incident surface 2a relative to the inclined surface, a particular transmissive surface 4a belongs to the inclined surface. This particular transmissive surface 4a is also parallel to the inclined surface. Except for the transmissive surface included in the inclined surface, some or all of the transmissive surfaces 4a are parallel to the inclined surface.

[0079] Since the inclined surfaces 24E, 25E, and 26E are tilted at the aforementioned angles, the ambient light beam, such as the ambient light beam L2, that passes through the light guide member 2E and reaches the inclined surfaces 24E, 25E, and 26E passes through the inclined surfaces 24E, 25E, and 26E and travels toward the display side.

[0080] The ambient light beams emitted from the inclined planes 24E, 25E, and 26E are parallel to the light beams that pass through some or all of the transmission surfaces 4a of the adjacent display-side steps 24, 25, and 26 near the incident surface 2a relative to the inclined planes. The ambient light beams emitted from the inclined planes 24E, 25E, and 26E are transmitted toward the display side at the same angle as the ambient light beams entering the incident surface 2a from outside the blind spot display device 1.

[0081] Therefore, the ambient light beams emitted from the inclined planes 24E, 25E, and 26E enable the driver, as the viewer, to visually recognize a view identical to the external environment.

[0082] For each inclined plane 24E, 25E, and 26E, the display-side step located near the incident surface 2a is called the preceding step, and the display-side step located near the end face 2d is called the following step. The following step corresponds to a specific step.

[0083] exist Figure 6 In the cross-section of the blind spot display device 1 shown, the length difference h between the flat portion 3a of the previous step closest to the next step and the flat portion 3a of the next step closest to the previous step in the opposite protrusion direction of the display side step is represented by the following numerical expression (4). The opposite protrusion direction is the direction opposite to the protrusion direction of the display side step.

[0084] h≤Wse / {tanΦ×(1-tanψ×tanΦ)} (4)

[0085] Here, Ψ is the acute angle of the inclined plane connecting the previous step and the next step relative to the opposite protruding direction. In the above expression (4), Φ is an acute angle and equal to the light guide angle Φ, which is formed between the external ambient light beam and the opposite protruding direction when the external ambient light beam passes through the light guide member 2e and exits from the exit surface 2b. In the above expression (4), Wse is the width of the prism portion 4 of the previous step, which is positioned closest to the next step in a direction perpendicular to the opposite protruding direction. The transmission surface 4a of the prism portion 4 closest to the next step constitutes part of the inclined plane.

[0086] In the above configuration, in the previous step, the ambient light beam L4 reflected at the point closest to the inclined surface in the flat section 3a is not blocked by the inclined surface and can pass through the light guide member 2e and move towards the blind spot side reflective surface 2c. Therefore, it is possible to prevent the ambient light beam L4 from escaping from the blind spot display device 1 due to the inclined surface blocking the beam, thus preventing it from becoming unnecessary light. In other words, the generation of unnecessary light can be suppressed. Note that... Figure 6 The cross section shown is... Figure 2 The cross-sections shown are the same.

[0087] The following describes the bevels 21W, 22W, and 23W. Each bevel 21W, 22W, and 23W is provided by a light-shielding surface. For example, each bevel 21W, 22W, and 23W can be completely covered by a light-absorbing film (not shown). Each bevel 21W, 22W, and 23W can be completely covered by different materials to serve as a light-shielding surface. Therefore, ambient light beams will not be emitted from the light guide member 2e through the bevels 21W, 22W, and 23W. External light from outside the blind spot display device 1 is also prevented from passing through the bevels 21W, 22W, and 23W into the light guide member 2e.

[0088] For each inclined plane 21W, 22W, and 23W, the display-side step located near the incident surface 2a is called the preceding step, and the display-side step located near the end face 2d is called the following step. The preceding step corresponds to a predetermined step.

[0089] The tilt angle of each of the ramps 21W, 22W, and 23W is set such that the ambient light beam emitted from the transmissive surface 4a, which is closest to the next step in the preceding step, toward the display side is not blocked by the ramp. More specifically, the ramp is parallel to some or all of the opposing surfaces 4b (i.e., the surfaces near the incident side) included in the preceding step. The tilt angle is set such that at least a portion of the ambient light beam transmitted through the transmissive surface 4a and emitted toward the display side is not blocked by the ramp. For example, the tilt angle may be set such that all ambient light beams transmitted through the transmissive surface 4a and emitted toward the display side are not blocked by the ramp. For example, the tilt angle may be set such that only a portion of the ambient light beams transmitted through the transmissive surface 4a and emitted toward the display side are not blocked by the ramp. For example, the tilt angle may be set such that the ambient light beam transmitted through the transmissive surface 4a and reaching the center of the eyelid EL is not blocked by the ramp. As another example, the tilt angle may be set such that the ambient light beam transmitted through the transmissive surface 4a, emitted toward the display side, and reaching the eyelid EL at its side end in the vehicle width direction is not blocked by the ramp.

[0090] The opposing surfaces 4b of each prism section 4 are arranged at a certain angle so that the opposing surfaces do not block the external ambient light beam directed toward the center end in the vehicle width direction toward the driver's eyelid EL. In other words, the external ambient light beam emitted from the transmission surface 4a of each prism section 4 will not be blocked by the adjacent opposing surfaces 4b arranged near the end face 2d.

[0091] Each ramp 21W, 22W, 23W is parallel to part or all of the opposing surface 4b in the preceding step. Therefore, it prevents the ambient light beam emitted from the transmission surface 4a of the preceding step towards the display side from being blocked by the length difference between two adjacent display-side steps. That is, by avoiding the length difference between two adjacent display-side steps, the ambient light beam emitted from the transmission surface 4a of the preceding step towards the display side can reach the driver's eyelids.

[0092] like Figure 2 and Figure 3 As shown, among the display-side steps 21 to 27, display-side step 24 protrudes most towards the display side, and display-side steps 21, 22, and 23 are positioned closer to the incident surface 2a than display-side step 24. In each display-side step 21 to 24, the prism portion 4 is arranged at its end on the incident surface 2a side, rather than on the flat portion 3a. With this configuration, the reflection and transmission of unnecessary light entering the display-side step from the outside of the blind spot display device 1 can be suppressed by the opposing surface 4b of the prism portion 4, which has light-shielding properties.

[0093] Of the display-side steps 21 to 27, display-side step 24 protrudes most towards the display side, and display-side steps 25, 26, and 27 are positioned closer to the end face 2d than display-side step 23. In each of the display-side steps 24 to 27, the prism portion 4 is arranged at its end on the end face 2d side, rather than on the flat portion 3a. The prism portion 4 arranged at its end on the end face 2d side of each display-side step has a width Wse in a direction perpendicular to the protrusion direction of the display-side step. The width Wse of the prism portion 4 arranged at its end on the end face 2d side of each display-side step is larger than the width of the other prism portions 4 in the same display-side step. By setting the width Wse of the end prism portion 4 to be greater than the width of the other prism portions 4, unwanted light can be prevented even if the slope height h in the opposite protrusion direction increases in view of the above numerical expression (4).

[0094] Each of the inclined surfaces 21W, 22W, and 23W is away from the incident surface 2a and becomes closer to the end face 2d in the direction toward the display side. Therefore, when the light guide component 2e is integrally molded using a molding die, the removal of the light guide component from the die can be performed in an easy manner.

[0095] As described above, the display-side vertex of the prism portion 4 is arranged in a three-dimensional manner rather than along a plane. With this arrangement, the display-side surface of the blind spot display device 1 appears to have a curved shape. For example, the prism portion 4 can be arranged such that the visual shape of the display-side surface of the blind spot display device 1 conforms to the surface shape of the front post 92 to which the blind spot display device is attached.

[0096] (i) The display-side reflective surface 3 is divided into a plurality of flat portions 3a, and the plurality of flat portions 3a are arranged alternately with a plurality of prism portions 4. That is, each flat portion 3a is sandwiched by a prism portion 4, and each prism portion 4 is sandwiched by a flat portion 3a. Each prism portion 4 protrudes further toward the display side than its adjacent portion (i.e., adjacent flat portion 3a) of the display-side reflective surface 3. The display-side reflective surface 3 is arranged in a three-dimensional manner as a whole rather than along a plane.

[0097] By arranging the display-side reflective surface 3 in a three-dimensional manner as described above, the need to achieve the three-dimensional shape solely through the protrusion level of the prism section 4 is reduced, and variations in the protrusion level of the prism section 4 can be suppressed. Therefore, the possibility that an ambient light beam emitted from a particular prism section 4 towards the display side can be blocked by another prism section can be reduced.

[0098] (ii) The exit surface 2b has multiple prism portions 4, and the display-side reflecting surface 3 has a stepped shape overall. As described above, the exit surface 2b includes multiple display-side steps 21 to 27. The multiple display-side steps 21 to 27 include a preceding step and a following step. The following step is adjacent to the preceding step and is farther away from the incident surface 2a relative to the preceding step. The following step protrudes further towards the display side than the preceding step. The preceding step corresponds to a specific display-side step, and the following step corresponds to the next display-side step. The inclined surfaces 21W, 22W, and 23W connecting the preceding step and the following step are arranged at an inclined angle, at which the ambient light beam from the prism portion passing through the preceding step (closest to the following step) toward the display side is not blocked by the inclined surface.

[0099] Since the slope is inclined as described above, the appearance of the display side surface of the blind spot display device 1 can have a curved shape, while suppressing the possibility that the visibility of external ambient light beams will be impaired by the slope.

[0100] (iii) In the plurality of prism sections 4, the inclined surfaces 21W, 22W, and 23W are configured to be parallel to the incident-side surface of at least one prism section in the preceding step. The incident-side surface of at least one prism section is a surface disposed in the prism section near the incident surface 2a. Similar to the incident surface 2a of the prism section 4 in the preceding step, the possibility of the visibility of the external ambient light beam being impaired by the inclined surfaces 21W, 22W, and 23W can be suppressed.

[0101] (iv) The above numerical expression (4) is based on a cross-section parallel to the external ambient light beam. The cross-section includes an incident surface 2a, a light guide member 2e, a display-side reflector 3, a blind-side reflector 2c, and multiple prism sections 4. By suppressing the height h as described above, it is possible to suppress the possibility that the light reflected from the portion of the display-side reflector 3 closest to the next step in the previous step will be blocked by the inclined surfaces 24E, 25E, and 26E connecting the previous and next steps before reaching the blind-side reflector 2c. As a result, light utilization efficiency can be improved.

[0102] (Second Embodiment)

[0103] The following will refer to Figure 7 and Figure 8 A second embodiment of this disclosure will be described. In this second embodiment, the main differences from the first embodiment will be described. In the blind spot display device 1 of this embodiment, the construction of the inclined surfaces 21W, 22W, 23W and the end face 2d differs from that of the first embodiment.

[0104] like Figure 7 As shown, each of the ramps 21W, 22W, and 23W becomes closer to the incident surface 2a and farther away from the end face in the direction toward the display side (i.e., toward the interior of the vehicle). More specifically, each of the ramps 21W, 22W, and 23W is a translucent plane arranged parallel to the incident surface 2a. The end face 2d is also a translucent plane arranged parallel to the incident surface 2a.

[0105] Therefore, each of the inclined planes 21W, 22W, and 23W is parallel to the incident surface 2a and is semi-transparent. With this configuration, ambient light beams emitted from adjacent transmission surfaces 4a positioned relative to the inclined planes and close to the incident surface 2a are incident on the inclined planes at a near-perpendicular angle of incidence without being reflected by the inclined planes. For example, among ambient light beams L7, L8, and L9 incident on the incident surface 2a at angles different from those of ambient light beams L1, L2, and L3, ambient light beams L8 and L9 enter inclined planes 21W and 23W, respectively. Since each of the inclined planes 21W, 22W, and 23W is parallel to the incident surface 2a, the angle of incidence is θ1+ψ. This angle of incidence is the same as the angle of incidence when the same ambient light beam is incident on the incident surface 2a, i.e., the acute angle θ1+ψ formed between the ambient light beam and the incident surface 2a. Light beams re-entering from the inclined planes 21W, 22W, and 23W pass through the light guide member 2e without being blocked. The beam is then emitted from another transmission surface 4a and reaches the occupant. This configuration reduces the likelihood that the ambient light beam transmitted from the incident surface 2a will be reflected by the inclined surfaces 21W, 22W, and 23W and travel in an unintended direction. The ambient light beam that re-enters the inclined surfaces 21W, 22W, and 23W and exits from the transmission surface 4a is parallel to the ambient light beam exiting from the other transmission surface 4a and does not pass through the inclined surfaces 21W, 22W, and 23W. Therefore, light utilization efficiency can be improved.

[0106] End face 2d is parallel to the incident surface 2a and is semi-transparent. An ambient light beam travels through the light guide member 2e, is reflected at the exit surface 2b and the blind spot side reflecting surface 2c, and then reaches end face 2d. The ambient light beam reaching end face 2d passes through end face 2d and heads towards the outside of the blind spot display device. Similar to the ambient light beam exiting from the transmission surface 4a, the ambient light beam exiting from end face 2d travels parallel to the ambient light beam entering the incident surface 2a. Therefore, the observation area for visually recognizing the ambient light beam is further widened.

[0107] In this embodiment, the light guide member 2e can be integrally molded or constructed by lamination molding. The light guide member 2e can be constructed by molding multiple thin plates and stacking multiple thin plates in the protruding direction of the blind spot display device 1, each thin plate having a plane intersecting the normal direction of the flat portion.

[0108] The correct use of the blind spot display device 1 according to the first embodiment and the blind spot display device according to the second embodiment will now be described. In the blind spot display device 1 of the first embodiment, the external environment light beam emitted from the transmission surface 4a, which may be reflected in an unexpected direction by the inclined surfaces 21W, 22W, and 23W, is the external environment light beam that reaches the driver's eyelid at the outer end in the vehicle width direction (e.g., the right end of a right-hand drive vehicle). Figure 8 As shown, the external ambient light beam L6 exits from the adjacent transmission surface 4a near the incident surface 2a, enters the inclined surfaces 21W, 22W, and 23W, and then reaches the outer end of the eyelid in the vehicle width direction. The angle of the external ambient light beam L6 exiting from the transmission surface 4a relative to the protrusion direction is set to θer. When the angle θer is greater than the tilt angle ε of the opposing surface 4b relative to the protrusion direction, the beam L6 is highly likely to be reflected in an unintended direction by the inclined surfaces 21W, 22W, and 23W. In this case, the configuration of the second embodiment can be applied.

[0109] In this embodiment, for each incident surface 21W, 22W, 23W, the prism portion 4 adjacent to the incident surface 2a in the preceding step can have a width Wse greater than the width of other prism portions 4 in the same preceding step. The width of the prism portion 4 is defined as the length of the prism portion 4 in the direction perpendicular to the protrusion direction of the display side step. By increasing the width Wse, the ambient light beam incident from the inclined plane can reach the transmission surface 4a of the multiple prism portions 4 included in the subsequent step. Therefore, the light utilization efficiency can be further improved.

[0110] (i) In this embodiment, the ambient light beam passes through the inclined planes 21W, 22W, and 23W connecting the previous step (corresponding to a specific display side step) and the next step (corresponding to the next display side step). The ambient light beam passes through the prism portion 4 of the previous step. Then, the ambient light beam enters the inclined planes 21W, 22W, and 23W. The inclined planes 21W, 22W, and 23W are tilted such that the angle of incidence of the ambient light beam relative to the inclined planes 21W, 22W, and 23W is the same as the angle of incidence θ1+ψ of the ambient light beam relative to the incident surface 2a.

[0111] The inclined surfaces 21W, 22W, and 23W are inclined in the manner described above. Therefore, when light that has passed through the prism section 4 toward the display side into the inclined surfaces 21W, 22W, and 23W, the light is again guided through the light guide member 2e. Thus, interference (i.e., vignetting) caused by reflections of external ambient light beams onto the inclined surfaces 21W, 22W, and 23W can be suppressed, and light utilization efficiency can be improved.

[0112] (ii) Each inclined plane 21W, 22W, 23W is parallel to the incident plane 2a. Since the inclined planes are parallel to the incident plane 2a, the angles satisfy the relationship described in (i) above.

[0113] In this embodiment, the configuration of the blind spot display device 1 (not described) can be configured to be the same as the corresponding configuration of the blind spot display device 1 in the first embodiment. Therefore, the same effect as in the first embodiment can be obtained by using the same configuration as in the first embodiment. The configuration of the end face 2d in this embodiment is also applicable to the first embodiment.

[0114] (Third Embodiment)

[0115] The following will refer to Figures 9 to 12 A third embodiment of this disclosure is described. In this third embodiment, the main differences from the first embodiment will be described. Figure 10 In order to illustrate the light guided in the light guide member 2e of the blind spot display device in an easily understandable way, different patterns are applied to the passage areas of the external ambient light beams L11, L12, L13, and L14.

[0116] like Figure 9 and Figure 10 As shown, the blind spot display device 1 of this embodiment differs from the first embodiment in that it includes an inclined surface 6 disposed between the incident surface 2a and the blind spot-side reflective surface 2c. The inclined surface forms part of the surface of the light guide member 2e. The inclined surface 6 protrudes from the blind spot-side reflective surface 2c toward the blind spot side. This difference will be mainly described in this embodiment.

[0117] The maximum distance between the blind-side reflecting surface 2c and the flat portion 3a in the direction normal to the flat portion is defined as height T0. The distance between the end of the incident surface 2a adjacent to the inclined surface 6 and the flat portion 3a in the direction normal to the flat portion is defined as height Td. Heights T0 and Td satisfy the relationship Td>T0.

[0118] By setting the inclined plane 6, the area of ​​the incident surface 2a is increased compared to the incident surface 2a in the first embodiment. In this configuration, the area of ​​the incident surface 2a through which the external ambient light beam enters the light guide member 2e is increased. Therefore, the area of ​​the external ambient light beam that first reaches the exit surface 2b increases accordingly. Thus, the amount of external ambient light beam guided by the light guide member 2e can be increased, and the gap of the guided beam can be reduced. The gap of the guided beam is the area where the user cannot visually identify the guided external ambient light beam, also known as the beam gap. When the gap of the guided beam is generated, the continuity of the external ambient light beam, i.e., the continuity displayed on the exit surface 2b, cannot be assured to the user.

[0119] The inclined surface 6 is covered with a light-absorbing film (not shown) to suppress the generation of ghosting images caused by unintentional incident light beams from the external environment and reflections of these beams at the interface. Specifically, when a light beam is incident on the incident surface 2a at an angle smaller than the incident angle θ1, a portion of the beam reaches the inclined surface 6. The light-absorbing film arranged on the inclined surface 6 absorbs the light reaching the inclined surface 6. Therefore, unwanted beams, such as those reflected at a portion different from the blind-side reflecting surface 2c, are prevented from being directed toward the exit surface 2b, thereby suppressing the generation of ghosting images.

[0120] like Figure 9 and Figure 10 As shown, the inclined surface 6 has a linear shape and connects the end of the incident surface 2a and the end of the blind-side reflecting surface 2c. The inclined surface 6 is designed such that the tilt angle ξ relative to the normal direction of the flat portion does not cause beam gaps in the guided external ambient beam L1 entering from the incident surface 2a.

[0121] For example, such as Figure 11 As shown, when the tilt angle ξ of the inclined plane 6 is greater than the guiding angle Φ of the external ambient beam L1, gaps may appear between the beams.

[0122] Specific examples are described below. For ease of explanation, the end of the incident surface 2a adjacent to the blind-side reflecting surface 2c is referred to as the first end 2aa, and the ambient light beam incident from the point adjacent to the first end 2aa is referred to as the incident beam L2a. The end of the blind-side reflecting surface 2c adjacent to the incident surface 2a is referred to as the second end 2ca, and the ambient light beam reflected at the point adjacent to the second end 2ca is referred to as the incident beam L2b.

[0123] When the tilt angle ξ of the inclined plane 6 is greater than the light guiding angle Φ, a gap is created between the incident light beam L2a passing through a point far from the second end portion 2ca and the incident light beam L2b reflected at a point adjacent to the second end portion 2ca. The gap between the incident light L2a and the incident light L2b is called the beam gap. When a beam gap occurs, the ambient light beam does not reach the portion of the prism section 4 included in the exit surface 2b. In this case, a gap appears in the guided beam, and the continuity of the display cannot be guaranteed.

[0124] Considering the above points, the inclined plane 6 is configured such that the tilt angle ξ of the inclined plane 6 is less than the light guide angle Φ. In this case, as... Figure 12 As shown, the incident light L2a passes through the point adjacent to the second end 2ca, and no gap is created between the incident light L2a and the incident light L2b. Therefore, the light guide member 2e has no gap between the light beams, nor between the guided light beams. Thus, the blind spot display device 1 can ensure the continuity of the display on the emitting surface 2b.

[0125] When the incident angle θ1 of the external ambient beam L1 is within the range of θ1±Δθ1 and the guiding angle Φ of the incident beams L2a and L2b is within the range of Φ±ΔΦ, the tilt angle ξ of the inclined plane 6 is configured to satisfy the relationship ξ<Φ-ΔΦ so that the generation of the beam gap is limited to the incident angle range of θ1±Δθ1.

[0126] The incident surface 2a can have a tilt angle ψ less than π / 2 - θ1. When the incident surface 2a (the refractive surface of the external ambient beam L1) satisfies the relationship ψ < π / 2 - θ1, the guiding angle Φ of the refracted incident beams L2a and L2b becomes greater than the incident angle θ1 of the external ambient beam L1. Therefore, in the light guide member 2e, the initial arrival width of the incident beams L2a and L2b becomes wider. Compared to the case where the guiding angle is θ1, the light guide width, i.e., the height T0 of the blind-side reflecting surface 2c, can be reduced to achieve a compact size.

[0127] The following describes the configuration of the blind spot display device 1, which differs from the first embodiment except for the inclined surface 6. As in the first embodiment, the emission surface 2b of this embodiment has a stepped shape, generally comprising multiple display-side steps. Specifically, the emission surface includes display-side steps 21, 22, 23, 24, 25, and 26 similar to those in the first embodiment, and the display-side step 27 of the first embodiment is omitted in this embodiment. The emission surface 2b of this embodiment includes inclined surfaces 21W, 22W, 23W, 24E, and 25E similar to those in the first embodiment, and the inclined surface 26E of the first embodiment is omitted in this embodiment.

[0128] The blind spot side reflector 2c of this embodiment has a stepped shape and includes multiple steps, such that the blind spot side reflector 2c is arranged in a three-dimensional manner rather than along a plane. Each of the multiple steps included in the blind spot side reflector 2c is called a blind spot side step and protrudes toward the blind spot side. Each blind spot side step corresponds to a second step. The positions of each blind spot side step in the protrusion direction are different from each other.

[0129] On the blind-spot side reflector 2c, multiple blind-spot side steps 31, 32, 33, and 34 are arranged along a direction from the side closer to the incident surface 2a to the side farther from the incident surface 2a. The blind-spot side steps 31 to 34 are parallel to each other in the protruding direction. The blind-spot side reflector 2c includes blind-spot side connecting surfaces 31E, 32E, and 33E, each of which is arranged between two adjacent blind-spot side steps 31 to 34. The blind-spot side connecting surfaces are also referred to as connecting surfaces.

[0130] The blind spot side step 32 is more recessed towards the display side than the blind spot side step 31, the blind spot side step 33 is more recessed towards the display side than the blind spot side step 32, and the blind spot side step 34 is more recessed towards the display side than the blind spot side step 33. Therefore, the blind spot side connecting surfaces 31E, 32E, and 33E face the end face 2d instead of the incident surface 2a. The blind spot side steps 31 to 34 and the blind spot side connecting surfaces 31E, 32E, and 33E constitute a pseudo-surface 2g. The pseudo-surface 2g is approximately composed of the blind spot side steps 31 to 34 and the blind spot side connecting surfaces 31E, 32E, and 33E.

[0131] Because the positions of the blind-spot side steps 31 to 34 differ from each other in the protrusion direction, the blind-spot side reflector 2c has a three-dimensional arrangement that is not along a plane. Note that the term "not along a plane" excludes situations where the arrangement deviates from a planar arrangement due to unavoidable manufacturing errors. For example, the term "not along a plane" means that when the shortest distance d from the position of each blind-spot side step 31, 32, 33, 34 to a specific reference plane P is d, the reference plane P is defined such that the sum of the shortest distances d among all blind-spot side steps 31, 32, 33, 34 is minimized. In this case, when the average d of the shortest distances d of all blind-spot side steps is 5% or greater than the longest distance Y of the blind-spot side reflector 2c, the blind-spot side reflector 2c is considered to be arranged in a three-dimensional manner rather than along a plane. Here, the longest distance Y is the distance between the two farthest points on the blind-spot side reflector 2c.

[0132] Due to the shapes of the blind spot side reflective surface 2c and end face 2d, the light guide member 2e has an overall meniscus shape, wherein the blind spot side surface has a shape approximating a pseudo-curved surface 2g, and the display side surface has a shape approximating a pseudo-curved surface 2f. This shape of the light guide member 2e reduces the possibility of physical interference between the front pillar 92 and the blind spot display device 1. Therefore, the blind spot display device 1 can be easily attached to a target object, such as the front pillar.

[0133] Similar to the exit surface 2b in the first embodiment, each blind-side step 31, 32, 33, 34 performs total internal reflection on external ambient light beams incident from the incident surface 2a and totally reflected by the flat portion 3a. The blind-side connecting surfaces 31E, 32E, 33E can be made light-shielding by arranging a light-absorbing film (not shown) on the blind-side connecting surfaces through a light-shielding treatment. This configuration prevents external ambient light beams traveling through the light guide member 2e from passing through the blind-side connecting surfaces 31E, 32E, 33E, being reflected on the front pillar 92, and then re-entering the light guide member 2e. Therefore, ghosting caused by reflection of the beam on the front pillar 92 can be reduced. Alternatively, the blind-side connecting surfaces 31E, 32E, 33E may not have light-shielding properties and allow the beam to pass through the blind-side connecting surfaces. In this case, when the components constituting the front pillar 92 have light-blocking properties at the portions of the blind spot side connection surfaces 31E, 32E, and 33E, the same effect as when the blind spot side connection surfaces 31E, 32E, and 33E have light-blocking properties can be achieved.

[0134] The locations of the blind spot side connection surfaces 31E, 32E, and 33E will be described below. For example... Figure 9 and Figure 10 As shown, compared to the inclined surface 21W, the blind-side connecting surfaces 31E, 32E, and 33E are located further away from the incident surface 2a. With this configuration, the blind-side connecting surfaces 31E, 32E, and 33E can reduce the gap in the guided beam. Here, the gap in the guided beam is created by the inclined surfaces 21W, 22W, and 23W, which have a stepped shape. For example, as... Figure 10 As shown, ambient light beams L11 and L12 are reflected by display-side steps 21 and 22, respectively, and then reflected again by blind-side steps 31 and 32, respectively. When the beams are reflected by display-side steps 21 and 22, a gap Px is created between the ambient light beams L11 and L12. This gap is reduced (e.g., completely eliminated) by the height difference between blind-side steps 31 and 32, and then the ambient light beams L11 and L12 are guided to the next display-side step. To achieve this, among the plurality of inclined planes 21W, 22W, and 23W, at least the inclined plane 21W closest to the incident surface 2a is positioned closer to the incident surface 2a than all blind-side connecting surfaces 31E, 32E, and 33E.

[0135] like Figure 10As shown, in an ambient light beam incident on the incident surface 2a at an incident angle θ1, the ambient light beam L11 is first totally reflected by the flat portion 3a of the display-side step 21, and then travels through the light guide member 2e. Afterwards, the ambient light beam L11 is further totally reflected by the blind-side step 31. The ambient light beam L11, totally reflected on the blind-side step 31, deviates from the blind-side connecting surface 31E and reaches the display-side step 24 without impacting the blind-side connecting surface 31E. In other words, the blind-side connecting surface 31E is arranged at a position where it does not obstruct the ambient light beam L11.

[0136] In an ambient light beam incident on the incident surface 2a at an incident angle θ1, the ambient light beam L12 is first totally reflected by the flat portion 3a of the display-side step 22, travels through the light guide member 2e, and then reaches the blind-side step 32. The ambient light beam L12 is totally reflected on the blind-side step 32 and then reaches the display-side step 24. The ambient light beam L2 reaches the blind-side step 32 without impacting the blind-side connecting surface 31E.

[0137] The blind spot side connection surface 31E is positioned such that the ambient light beam L11 reflected by the blind spot side step 31 reaches the display side step 24 without being blocked by the blind spot side connection surface 31E. The blind spot side connection surface is positioned such that all ambient light beams L12 reach the blind spot side step 32 without being blocked by the blind spot side connection surface 31E. In other words, the blind spot side connection surface 31E is arranged in a beam non-passage area where neither ambient light beam L11 nor ambient light beam L12 passes.

[0138] When the blind spot side connection surface 31E is not positioned as described above, one or both of the external ambient beams L11 and L12 are blocked by the blind spot side connection surface 31E. Therefore, when the external ambient beams L1 and L2 are emitted outward from the transmission surface 4a of the display side step 24, the gap generated between the guided external ambient beams L2 and L1 increases.

[0139] By arranging the blind spot side connection surface 31E in a beam-non-passage region where neither the external ambient beam L11 nor the external ambient beam L12 passes, the gap between the external ambient beams L11 and L12 is reduced when they are emitted outward from the transmission surface 4a of the display-side step 24. Therefore, brightness uniformity in the image viewed by the driver can be suppressed. The same applies to the blind spot side connection surfaces 32E and 33E.

[0140] like Figure 9 and Figure 10As shown, in the display-side step 26 closest to the end face 2d, no flat portion 3a is provided, and multiple prism portions 4 are arranged adjacently and continuously. When an external ambient light beam undergoes total internal reflection on the display-side step 24 closest to the end face 2d, the reflected beam will strike the end face 2d and generate unwanted light. By arranging prism portions 4 adjacently and continuously on the display-side step 24 closest to the end face 2d, the amount of external ambient light beam emitted from the transmission surface 4a of the prism portion 4 to the display side is increased, thereby improving light utilization efficiency and limiting the generation of unwanted light.

[0141] Two adjacent display-side steps constitute a pair of display-side steps. In this pair, the display-side step closer to the driver (i.e., farther from the incident surface 2a) is located more inside the vehicle width direction (i.e., on the display side in the direction of the normal to the flat portion) than the other display-side step. This pair of display-side steps is also referred to as a pair of display-side steps. The configuration of this embodiment includes multiple pairs of display-side steps, namely a pair including display-side steps 21 and 22, a pair including display-side steps 22 and 23, and a pair including display-side steps 23 and 24.

[0142] Two adjacent blind spot side steps constitute a pair of blind spot side steps. In this pair, the blind spot side step closer to the driver (i.e., farther from the incident surface 2a) is located further inside in the vehicle width direction (i.e., the display side in the direction of the normal to the flat portion) compared to the other blind spot side step. This pair of blind spot side steps is also referred to as a blind spot side step pair. The configuration of this embodiment includes multiple pairs of blind spot side steps, namely a pair including blind spot side steps 31 and 32, a pair including blind spot side steps 32 and 33, and a pair including blind spot side steps 33 and 34.

[0143] In this embodiment, the number of display-side step pairs is equal to the number of blind-side step pairs. When the number of display-side step pairs is greater than the number of blind-side step pairs, the gap generated between adjacent ambient light beams guided by total internal reflection from the light guide increases. The driver can visually perceive this gap as brightness non-uniformity. Therefore, when the gap generated between adjacent ambient light beams guided by total internal reflection from the light guide increases, the brightness non-uniformity of the ambient light beams increases. When the number of display-side step pairs is less than the number of blind-side step pairs, the amount of unnecessary light generated when the ambient light beams enter the blind-side connecting surface increases. Here, the blind-side connecting surface corresponds to the height difference between two adjacent blind-side steps. Therefore, light utilization efficiency decreases. When the number of display-side step pairs is set to be equal to the number of blind-side step pairs, compared to the case where the number of display-side step pairs is different from the number of blind-side step pairs, brightness non-uniformity decreases and light utilization efficiency increases.

[0144] (i) As described above, the blind spot side reflective surface 2c of this embodiment has a stepped shape and includes multiple blind spot side steps 31, 32, 33, and 34, so that the blind spot side reflective surface 2c is arranged in a three-dimensional manner instead of along a plane. The shape of the blind spot side reflective surface reduces the possibility of physical interference between the front pillar 92 and the blind spot display device 1. The front pillar 92 is the target object to which the blind spot display device 1 is attached.

[0145] (ii) The blind spot display device 1 has multiple blind spot side connecting surfaces 31E, 32E, and 33E, each connecting surface connecting two adjacent blind spot side steps 31, 32, 33, and 34. Compared to the inclined surface 21W connecting the display side step 21 closest to the incident surface 2a and the second display side step 22 closest to the incident surface 2a, the blind spot side connecting surfaces 31E, 32E, and 33E are positioned further away from the incident surface 2a. With this configuration, the blind spot side connecting surfaces 31E, 32E, and 33E can reduce the gap generated in the guided beam. As described above, the gap in the guided beam is generated by the inclined surfaces 21W, 22W, and 23W, which have a step shape.

[0146] (iii) In this embodiment, the number of display-side step pairs is equal to the number of blind-side step pairs. Compared to setting the number of display-side step pairs to be different from the number of blind-side step pairs, this configuration can reduce brightness non-uniformity and improve light utilization efficiency.

[0147] In this embodiment, the configuration of the blind spot display device 1 (not described) can be configured to be the same as the corresponding configuration of the blind spot display device 1 in the first embodiment. In this embodiment, by using the same configuration as the first embodiment, the same effects as the first embodiment can be obtained. In this embodiment, the same changes made to the first embodiment as in the second embodiment can also be applied.

[0148] (Fourth Embodiment)

[0149] The following will refer to Figures 13 to 17 A fourth embodiment of this disclosure is described. In this fourth embodiment, the main differences from the third embodiment will be described. Figure 13 As shown, compared to the blind spot display device 1 according to the third embodiment, the blind spot display device 1 of this embodiment does not have the inclined surface 6, and the position of the incident surface 2a is different from that of the third embodiment. Furthermore, compared to the third embodiment, the blind spot display device 1 of this embodiment also includes the inclined surface 7. In the exit surface 2b, the inclined surface 23W and the display-side step 24 are removed. In the blind spot-side reflective surface 2c, the blind spot-side connecting surface 33E and the blind spot-side step 34 are removed.

[0150] The distance T from the flat portion 3a of the display-side step 21 to the blind-side step 31 along the normal direction of the flat portion is the same as the distance from the flat portion 3a of the display-side step 22 to the blind-side step 32 along the normal direction of the flat portion. The distance T from the flat portion 3a of the display-side step 21 to the blind-side step 31 along the normal direction of the flat portion is the same as the distance from the flat portion 3a of the display-side step 23 to the blind-side step 33 along the normal direction of the flat portion.

[0151] A light-absorbing film (not shown) can be applied to the inclined surface 7 by applying a light-blocking treatment. Therefore, the incident and emission of unwanted light can be suppressed.

[0152] In this embodiment, the incident surface 2a is arranged parallel to the exit surface 2b and the blind-side reflective surface 2c. The incident surface 2a is arranged away from the exit surface 2b. One end of the incident surface 2a is connected to the end of the blind-side reflective surface 2c without a step (i.e., height difference). The other end of the incident surface 2a is connected to one end of the inclined surface 7. The other end of the inclined surface 7, opposite to the incident surface 2a, is connected to the exit surface 2b. The incident surface 2a is arranged opposite to the display-side step 21 of the exit surface 2b.

[0153] The incident surface 2a has a plurality of incident prism portions 41 arranged continuously adjacent to each other from the end of the incident surface 2a near the inclined surface 7 (i.e. the end of the incident surface adjacent to the windshield 94) toward the end surface 2d.

[0154] Each incident prism portion 41 includes an incident transmission surface 41a and an opposing surface 41b. Each of the incident transmission surface 41a and the opposing surface 41b protrudes toward the blind spot side and is translucent. In each incident prism portion 41, the incident transmission surface 41a is arranged further away from the end face 2d than the opposing surface 41b. That is, in each incident prism portion, the opposing surface 41b is arranged closer to the end face 2d than the incident transmission surface 41a.

[0155] Each incident transmission surface 41a is arranged parallel to the transmission surface 4a of each prism portion 4 included in the display-side reflective surface. That is, the tilt angle ψ (which is an acute angle formed between the normal direction of the flat portion and the incident transmission surface 41a) is the same as the tilt angle ψ (which is an acute angle formed between the normal direction of the flat portion and the transmission surface 4a). Therefore, when the external ambient light beam incident on the incident transmission surface 41a finally exits from the transmission surface 4a, the external ambient light beam incident on the incident transmission surface 41a is parallel to the external ambient light beam emitted from the transmission surface 4a.

[0156] A light-absorbing film (not shown) can be arranged on each opposing surface 41b by applying a light-blocking treatment. Therefore, the incident and outgoing of unwanted light passing through the opposing surface 41b can be suppressed.

[0157] The reason for the above-mentioned setting of the incident surface 2a will be described below. For example... Figure 13 As shown, external ambient light beams L21, L22, and L23 pass through light guide member 2e after entering from incident surface 2a. Figure 13 In order to illustrate the light guided in the light guide member 2e in an easily understandable way, different patterns are applied to the passage areas of the external ambient light beams L21, L22, and L23.

[0158] After entering the incident surface 2a, the ambient light beam L21 is emitted through the transmission surface 4a of the display-side step 21 or the transmission surface 4a of the display-side step 22, without being reflected even once by the flat portion 3a. The arrangement direction of the incident transmission surface 41a of the incident prism portion 41 is parallel to the arrangement direction of the transmission surface 4a of the display-side step 21. Therefore, the ambient light beam L21 incident on different incident transmission surfaces 41 has the same optical length from incident to exit on the incident surface 2a. Here, the term "exit" means that the beam reaches a plane that is perpendicular to the normal direction of the flat portion and closer to the user position than the exit surface 2b.

[0159] The ambient light beam L22 is reflected only once by the flat portion 3a after entering the incident surface 2a, and further reflected once by the blind spot side step 31 or blind spot side step 32. Then, the ambient light beam L22 reaches the display side step 22 or display side step 23, and is emitted outward through the transmission surface 4a of the display side step 22 or 23. When the ambient light beam L22 is reflected by the flat portion 3a of the display side step 21, it is subsequently reflected by the blind spot side step 31. When the ambient light beam L22 is reflected by the flat portion 3a of the display side step 22, it is subsequently reflected by the blind spot side step 32. As described above, the distance from the flat portion 3a of the display side step 21 to the blind spot side step 31 along the normal direction of the flat portion is the same as the distance from the flat portion 3a of the display side step 22 to the blind spot side step 32 along the normal direction of the flat portion. Therefore, the external ambient light beam L22 incident on different incident transmission surfaces 41a has the same optical length from incident to exit on the incident surface 2a.

[0160] After entering the incident surface 2a, the ambient light beam L23 is reflected twice by the flat portion 3a and then twice more by the blind spot side step. The first reflection on the blind spot side step can be a reflection on blind spot side steps 31 or 32, and the second reflection can be a reflection on blind spot side steps 32 or 33. Then, the ambient light beam L23 reaches the display side step 22 or 23 and is emitted outward through the transmission surface 4a of the display side step 22 or 23. When the ambient scene light L23 is reflected by the flat portion 3a of the display side step 21, the ambient light beam L23 is subsequently reflected by the blind spot side step 31. When the ambient light beam L23 is reflected by the flat portion 3a of the display side step 22, the ambient light beam L23 is subsequently reflected by the blind spot side step 32. When the ambient light beam L23 is reflected by the flat portion 3a of the display side step 23, the ambient light beam L23 is subsequently reflected by the blind spot side step 33. As described above, the distance from the flat portion 3a of the display-side step 21 to the blind-side step 31 along the normal direction of the flat portion is the same as the distance from the flat portion 3a of the display-side step 22 to the blind-side step 32 along the normal direction of the flat portion. The distance from the flat portion 3a of the display-side step 21 to the blind-side step 31 along the normal direction of the flat portion is the same as the distance from the flat portion 3a of the display-side step 23 to the blind-side step 33 along the normal direction of the flat portion. Therefore, the ambient light beam L23 incident on different incident transmission surfaces 41a has the same optical length from incident to exit on the incident surface 2a.

[0161] The optical path lengths of the external environmental beam L21 from the incident surface 2a to the exit, the optical path lengths of the external environmental beam L22 from the incident surface 2a to the exit, and the optical path lengths of the external environmental beam L23 from the incident surface 2a to the exit are all different from each other.

[0162] On the exit surface 2b, the optical path length becomes constant in each of the relatively wide ranges of the emitted external environment beam L21, the relatively wide ranges of the emitted external environment beam L22, and the relatively wide ranges of the emitted external environment beam L23. Therefore, the distortion in the external environment image visually recognized by the emitted beams can be roughly divided into a first boundary region and a second boundary region. The first boundary region is the area between the ranges of the emitted external environment beam L21 and L22. The second boundary region is the area between the ranges of the emitted external environment beam L22 and L23.

[0163] Within the range of the emitted ambient light beam L21, when the optical path length of the ambient light beam L21 varies depending on the distance from the incident surface 2a to the transmission surface 4a, it is assumed that the ambient light beam enters the incident surface 2a of the blind spot display device 1 in a direction angled to the vehicle's horizontal plane. In this case, the ambient light beam L21, which has the same position in the vertical direction of the vehicle when entering the incident surface 2a, has different positions on a plane perpendicular to the normal direction of the flat portion in the vertical direction of the vehicle. The plane perpendicular to the normal direction of the flat portion is defined as a plane closer to the driver's position than the exit surface 2b. As a result, distortion of the ambient light beam may occur. For example, when the ambient light beam L21 is transmitted from an infinitely far position as described above, the arrival position of the ambient light beam L21 in the vertical direction of the vehicle depends on the difference in optical path length caused by the blind spot display device 1. It is assumed that when the ambient light beam reaches the eyelid EL, the position of the ambient light beam entering the incident surface 2a changes. In a configuration where the angular relationship between the incident surface 2a and the transmission surface 4a remains the same at every position in the vertical direction of the vehicle, the external ambient beam L21 will not be distorted even if the optical path length of the external ambient beam is different. This is because the external ambient beam L21 is incident on the incident surface 2a as a parallel beam. When the external ambient beam L21 is transmitted from a finite distance, even if the position of the external ambient beam in the vertical direction of the vehicle is the same when entering the incident surface 2a, the position of the external ambient beam may change when the beam reaches each eyelid EL of both eyes. Distortion of the external ambient beam L21 occurs because the position of the external ambient beam is offset in the vertical direction of the vehicle. When a person views a fixed point, when there is parallax in the straight line connecting the left and right eyes, image generation is achieved by adjusting the convergence angle of the left and right eyes. In most cases, the direction of the straight line is usually consistent with the horizontal direction of the vehicle. In the case of parallax in the vertical direction of the vehicle, it is difficult to adjust the convergence angle of the left and right eyes, and visibility tends to deteriorate due to the aforementioned distortion of the external ambient beam L21. This is an example of how the orientation of the blind spot display device 1 is determined such that the normal direction of the flat portion and the normal direction of the incident surface 2a are parallel to the horizontal plane of the vehicle.

[0164] The following describes an example of the blind spot display device 1 rotating at an angle equal to or greater than 0 degrees and less than 90 degrees around the normal direction of the flat portion, which serves as the axis. That is, an example of the blind spot display device 1 being tilted will be described. In this configuration, it is assumed that the ambient light beam L21 enters the incident surface 2a in the horizontal direction of the vehicle. In such an example, within the range of the emission of the ambient light beam L21, when the optical path length of the ambient light beam L21 changes according to the distance from the incident surface 2a to the transmission surface 4a, the ambient light beam L21 that has entered the incident surface 2a is emitted from the transmission surface 4b along the horizontal direction of the vehicle in a configuration where the incident surface 2a is parallel to the transmission surface 4a. As described above, the blind spot display device 1 is placed in a tilted manner. Therefore, due to the refraction of the ambient light beam L21 on the incident surface 2a, it is deflected in the vertical direction of the vehicle. That is, when the external ambient light beam L21 is emitted through the transmission surface 4a, its position in the vertical direction of the vehicle is offset from its position in the vertical direction of the vehicle when it enters the incident surface 2a. The position offset increases with the increase of the optical path length. Within the range of the emitted external ambient light beam L21, when the optical path length changes, distortion of the external ambient light beam L21 occurs, i.e., parallax in the vertical direction of the vehicle. As described in this embodiment, within the range of the emitted external ambient light beam L21, the optical path length is constant regardless of the distance from the incident surface 2a to the transmission surface 4a, and the parallax of the external ambient light beam incident on the incident surface can be reduced in the vertical direction of the vehicle.

[0165] In the display side step 23, prism sections 4 and flat sections 3a are alternately arranged within the emission range of the external ambient beam L22. Within the emission range of the external ambient beam L23, only multiple prism sections 4 are continuously arranged without flat sections 3a. This is because, within the emission range of the external ambient beam L23, all the external ambient beam L23 is emitted through the transmission surface 4a without reflection, which improves light utilization efficiency.

[0166] The width W of the incident prism section 41 (i.e., prism array) arranged on the incident surface 2a in the arrangement direction is equal to or slightly different from the value obtained by the expression 2T×tanΦ. For example, the width W is within ±5% of the value obtained by the expression 2T×tanΦ. Here, Φ is the guiding angle of the external ambient light beam incident at an incident angle of θ1.

[0167] Reference Figure 14 , Figure 15 and Figure 16 Describe the reason. In Figure 13 In order to illustrate the light guided in the light guide member 2e in an easily understandable way, a pattern is applied to the area through which the external ambient light beam passes. Figure 14The optical path of the ambient light beam is shown when W = 2T × tanΦ. In this case, the ambient light beam L31, incident from the incident transmission surface 41a closest to the windshield 94 (i.e., the side furthest from the end face 2d) of the incident surface 2a, is reflected by the flat portion 3a of the display side step 21 closest to the vehicle windshield 94. The ambient light beam L31 is further reflected by the blind spot side step 31 closest to the windshield 94 and travels towards the transmission surface 4a of the blind spot side step 31 or the transmission surface 4a of the blind spot side step 32. The ambient light beam L32 enters the incident transmission surface 41a furthest from the windshield 94 (i.e., closest to the end face 2d) of the incident surface 2a, and then travels towards the transmission surface 4a of the blind spot side step 31 or the transmission surface 4a of the blind spot side step 32. In this case, there is almost no gap between the ambient light beam L31 and the ambient light beam L32. That is, the non-uniformity of the brightness of the ambient light beam can be reduced.

[0168] Figure 15 The optical path of the external ambient beam is shown when the width W is less than the value obtained by the expression 2T×tanΦ. In this case, the gap between the external ambient beams L32 and L31 increases, that is, the brightness non-uniformity of the external ambient beams increases.

[0169] Figure 16 The optical path of the ambient light beam is shown when the width W is greater than the value obtained by the expression 2T×tanΦ. In this case, the ambient light beam L31 incident from the incident transmission surface 41a closest to the windshield 94 on the incident surface 2a is reflected by the flat portion 3a of the display side step 21 closest to the vehicle windshield 94. The reflected beam then strikes the opposite surface 41b of the incident surface 2a. When the opposite surface 41b is translucent, the ambient light beam L31 is emitted outward through the light guide member 2e. When the opposite surface 41b has light-blocking properties, the ambient light beam L31 is blocked by the opposite surface 41b. That is, loss of the ambient light beam occurs. Figure 16 As shown, when the width W is greater than the value obtained by the expression 2T×tanΦ, there is almost no gap between the ambient beams. Therefore, if the loss of the ambient beams is acceptable, the width W can be set to W≥2T×tanΦ. By setting this width W, the unevenness of brightness can be reduced.

[0170] This embodiment includes two display-side step pairs: one pair consisting of display-side step 21 and display-side step 22, and another pair consisting of display-side step 22 and display-side step 23. These two display-side step pairs are partially identical to those described in the third embodiment. This embodiment also includes two dead-spot-side step pairs: one pair consisting of dead-spot-side step 31 and dead-spot-side step 32, and another pair consisting of dead-spot-end step 32 and dead-spot-end step 33. These two dead-spot-side step pairs are partially identical to those described in the third embodiment. Therefore, effects similar to those of the first embodiment can be achieved. When the number of display-side step pairs is set equal to the number of dead-spot-side step pairs, compared to the case where the number of display-side step pairs is different from the number of dead-spot-side step pairs, brightness non-uniformity is reduced and light utilization efficiency is improved.

[0171] Figure 17 The blind spot display device 1 according to this embodiment is shown attached to the front pillar 92 of a vehicle. In this state, the incident surface 2a is arranged toward the blind spot area blocked by the front pillar 92.

[0172] In this embodiment, the configuration of the blind spot display device 1 (not described) can be the same as the corresponding configuration of the blind spot display device 1 according to the first to third embodiments. In this embodiment, by using the same configuration as the first to third embodiments, the same effects as the first to third embodiments can be obtained.

[0173] (Other embodiments)

[0174] This disclosure is not limited to the above embodiments and may be modified as appropriate. The above embodiments are not independent of each other and may be appropriately combined unless such combination is obviously impossible. The components(one or more) of each of the above embodiments are not necessarily necessary unless specifically stated that the components(one or more) are necessary in the above embodiments or unless the components(one or more) are obviously necessary in principle. The quantities, values, numbers, ranges, etc., mentioned in the description of the above embodiments are not necessarily limited to the specific values, numbers, or ranges described, unless they are specifically described as necessary or understood to be necessary in principle. When multiple values ​​are exemplified for a parameter, a single value may also be used among the multiple values ​​unless an exclusion statement is made or it is obviously impossible in principle. The shape, positional relationship, etc., of the structural elements mentioned in the above embodiments are not limited to the described shape, positioning relationship, etc., unless specifically described in principle or obviously required to be limited. This disclosure also includes the following modifications based on the above embodiments and are included within the equivalent scope of the above embodiments. The following modifications may be independently chosen to be applied to or not applied to the above embodiments. That is, the following modifications may be appropriately combined with each other and may be applied to the above embodiments.

[0175] (First Amendment Example)

[0176] In each of the above embodiments, the display-side reflective surface 3 of the emitting surface 2b has a plurality of flat portions 3a and a plurality of prism portions 4 arranged alternately with each other. Specifically, each flat portion 3a is sandwiched between two prism portions 4, and each prism portion 4 is sandwiched between two flat portions. Each of the plurality of flat portions 3a is separated from each other, and each of the plurality of prism portions 4 is separated from each other. Through the plurality of flat portions 3a, the external ambient light beam can be totally reflected toward the blind-side reflective surface 2c. This configuration can be modified as follows. For example, the reflective portion for totally reflecting the external ambient light beam toward the blind-side reflective surface 2c may not be provided between the prism portions 4. Optionally, as disclosed in JP 2015-143087a, the reflective portion for totally reflecting the external ambient light beam may be provided at a position between the prism portion 4 and the blind-side reflective surface 2c.

[0177] (Second Amendment)

[0178] In each of the above embodiments, the emitting surface 2b has multiple display-side steps, and the protrusion level of the flat portion 3a towards the display side in one display-side step is different from the protrusion level of the flat portion 3a towards the display side in another display-side step. This configuration can be modified as follows. For example, in each display-side step, the protrusion level of the flat portion 3a towards the display side can be the same for each other. In this configuration, by setting the protrusion levels of the multiple prism portions 4 towards the display side to be different for each other, the end faces of the vertices of the multiple prism portions 4 can be arranged in a three-dimensional manner instead of along a plane.

[0179] (Third Amendment Example)

[0180] In the above embodiment, the flat portion 3a has a flat shape. In another example, the flat portion may have a shape other than a flat shape. In some embodiments, the blind spot side 2c is smoothly shaped. Optionally, the blind spot side reflective surface 2c does not necessarily have to be smooth.

[0181] (Fourth Amendment Example)

[0182] The blind spot display device 1 disclosed herein is attached to the front pillar 92 of a vehicle. The target object to which the blind spot display device 1 is attached can be any object other than the front pillar 92 of the vehicle. For example, the blind spot display device 1 can be attached to the center pillar of the vehicle located in the longitudinal direction. Alternatively, the blind spot display device 1 can be attached to a location outside the vehicle. For example, when the blind spot display device 1 is attached to a door of a building, the blind spot display device 1 can provide a similar effect.

Claims

1. A blind spot display device that displays an image of a blind spot obstructed by an obstacle, the blind spot display device comprising: An incident surface through which an ambient light beam enters, and the ambient light beam is transmitted from the blind point; A light guide component that guides the light beam entering the external environment through the incident surface; A first reflective surface is disposed opposite to the blind spot relative to the light guide member, and the external ambient light beam guided by the light guide member is reflected on the first reflective surface; A second reflective surface is arranged close to the blind spot relative to the light guide member. The second reflective surface is opposite to the first reflective surface, and the external ambient light beam guided by the light guide member is reflected on the second reflective surface. and Multiple prisms, arranged opposite to the blind spot relative to the light guide member and protruding towards the display area, are provided. The display area is defined as the region opposite to the blind spot relative to the light guide member. The ambient light beam, after traveling through the light guide member, is emitted towards the display area through the multiple prisms. in The ambient light beam enters the light guide member through the incident surface, and then travels along the arrangement direction of the plurality of prisms away from the incident surface while being alternately reflected on the first and second reflecting surfaces. A portion of the external ambient light beam is emitted toward the display area through the plurality of prisms, and The vertices of the plurality of prisms are arranged in a three-dimensional manner rather than along a plane.

2. The blind spot display device according to claim 1, wherein... The first reflective surface comprises a plurality of sub-surfaces separated from each other, and the plurality of sub-surfaces are arranged alternately with the plurality of prism portions. Each of the plurality of prism portions protrudes further toward the display area than any of the adjacent two of the plurality of sub-surfaces, and The first reflective surface is arranged in a three-dimensional manner rather than along a plane.

3. The blind spot display device according to claim 2, wherein... The plurality of prism portions and the first reflecting surface as a whole have a stepped shape, and the stepped shape includes a plurality of first steps. The plurality of first steps includes a specific first step and a subsequent first step arranged adjacent to the specific first step in a direction away from the incident surface. The latter first step protrudes further toward the display area than the particular first step. The specific first step is connected to the subsequent first step via an inclined plane. One of the external ambient light beams, directed toward the display area, passes through one of the plurality of prisms, which is included in the specific first step and is arranged closest to the latter first step. The ramp is arranged such that one of the external ambient light beams is not blocked by the ramp.

4. The blind spot display device according to claim 3, wherein... The plurality of prism portions includes a specific prism portion arranged on the specific first step, and the specific prism portion has a surface arranged close to the incident surface. The inclined surface connecting the specific first step and the subsequent first step is parallel to the surface of the specific prism portion that is arranged near the incident surface.

5. The blind spot display device according to claim 2, wherein... The plurality of prism portions and the first reflecting surface as a whole have a stepped shape, and the stepped shape includes a plurality of first steps. The plurality of first steps includes a specific first step and a subsequent first step arranged adjacent to the specific first step in a direction away from the incident surface. The latter first step protrudes further toward the display area than the particular first step. The specific first step is connected to the subsequent first step via an inclined plane. The plurality of prism portions includes a specific prism portion arranged on the specific first step. One of the external ambient light beams passes through the specific prism portion toward the display area, and then enters the inclined plane, and The inclined plane is tilted such that the angle of incidence of one of the external ambient beams relative to the inclined plane is equal to the angle of incidence of one of the external ambient beams relative to the incident plane (θ1+Ψ).

6. The blind spot display device according to claim 5, wherein... The inclined plane is parallel to the incident plane.

7. The blind spot display device according to claim 2, wherein... The plurality of prism portions and the first reflecting surface as a whole have a stepped shape, and the stepped shape includes a plurality of first steps. The plurality of first steps includes a specific first step and a preceding first step arranged adjacent to the specific first step in the direction toward the incident surface. The preceding first step protrudes further toward the display area than the specific first step. The external ambient light beam enters the incident surface parallel to the cross-section of the blind spot display device. The cross-section of the blind spot display device includes the incident surface, the light guide member, the first reflective surface, the second reflective surface, and the plurality of prism portions. The distance (h) defined in the protruding direction between the portion of the first reflective surface arranged in the preceding first step and the portion of the first reflective surface arranged in the preceding first step and the portion of the first reflective surface arranged in the preceding first step and the portion of the first reflective surface closest to the preceding first step satisfies the following relationship expression. The protruding direction is defined as the direction in which the specific first step or the preceding first step protrudes towards the display area. The inclined angle (Ψ) of the slope connecting the specific first step and the previous first step relative to the protruding direction is an acute angle, and satisfies the following relationship expression: When the ambient light beam passes through the light guide member and is reflected on the first reflective surface, the light guide angle (Φ) of the ambient light beam relative to the protruding direction is defined, and the light guide angle satisfies the following relationship expression. Of the plurality of prism portions, one included in the preceding first step is configured to be closest to the specific first step, and the width (Wse) of said one of the plurality of prism portions is defined in a direction perpendicular to the protrusion direction, and the width (Wse) satisfies the following relational expression. The relational expression is h≤ Wse / {tanΦ×(1- tanψ×tanΦ)}.

8. The blind spot display device according to any one of claims 2-7, wherein The second reflective surface has a stepped shape, and the stepped shape includes a plurality of second steps, and The second reflective surface is arranged in a three-dimensional manner rather than along a plane.

9. The blind spot display device according to any one of claims 3-7, wherein The second reflective surface has a stepped shape, and the stepped shape includes a plurality of second steps (31, 32, 33, 34). The second reflective surface is arranged in a three-dimensional manner rather than along a plane. The blind spot display device further includes multiple connecting surfaces, each of which connects two adjacent second steps in the plurality of second steps. In a direction away from the incident surface, the plurality of connecting surfaces are arranged further away than the inclined surface connecting the one of the plurality of first steps closest to the incident surface and the other of the plurality of first steps closest to the incident surface.

10. The blind spot display device according to any one of claims 3-7, wherein The second reflective surface has a stepped shape, and the stepped shape includes a plurality of second steps (31, 32, 33, 34). The second reflective surface is arranged in a three-dimensional manner rather than along a plane. A portion of the plurality of first steps is arranged such that one of the plurality of first steps farther from the incident surface protrudes more toward the display area than its adjacent one closer to the incident surface. The portion of the plurality of first steps is divided into one or more pairs of first steps, each pair of first steps comprising two adjacent first steps. A portion of the plurality of second steps is arranged such that one of the plurality of second steps farther from the incident surface is positioned closer to the display area than its adjacent counterpart closer to the incident surface. The portion of the plurality of second steps is divided into one or more pairs of second steps, each pair of second steps comprising two adjacent second steps from the plurality of second steps, and The number of the one or more first step pairs is equal to the number of the one or more second step pairs.

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