Optical member

Abstract

An optical member includes a light guide (2). The light guide has an incident surface (2a, 7a) on which external light is incident, a first surface (2b) having a flat portion (3) and a prism portion (4) to which the incident light incident on the incident surface reaches for the first time, and a second surface (2c) disposed opposite the flat portion. The flat portion totally reflects the incident light toward the second surface. The second surface totally reflects the reflected light reflected by the flat portion toward the first surface. The prism portion has an emission surface (4a) that emits the incident light to the outside.

Description

Technical Field

[0001] This disclosure relates to an optical component that internally reflects a portion of light incident from an incident surface and emits both incident and reflected light from a surface different from the incident surface to the outside. Background Technology

[0002] JP 6372305 B discloses an optical component having a light guide and a translucent mirror. The light guide has an incident surface on which external light is incident, a first surface to which the external light first travels after incident on the incident surface, and a second surface opposite to the first surface. The translucent mirror is arranged adjacent to the first surface. In this optical component, a portion of the external light incident from the incident surface is reflected to the second surface by the translucent mirror, and the remainder is absorbed or transmitted by the translucent mirror. The optical component has a prism sheet, on which prisms are arranged on the first surface, and light transmitted through the translucent mirror is emitted to the outside through the prisms.

[0003] As a result, external light incident from the incident surface is emitted over a wide area by the prism onto a first surface different from the incident surface. Therefore, a user located near the first surface can visually identify the scene behind the incident surface. This optical component is used, for example, as a blind spot assist device arranged on a predetermined obstacle, which allows the user to visually identify the scene in a blind spot area that is blocked by the obstacle and cannot be directly seen by the user. Summary of the Invention

[0004] Semitransparent mirrors are made of, for example, a single-layer metal vapor deposition film obtained by depositing a metallic material or a dielectric multilayer coating film obtained by coating a dielectric material in multiple layers.

[0005] However, when a translucent mirror is composed of a single-layer metal vapor deposition film, the light absorption rate in the metal vapor deposition film is high, and the loss due to multiple light reflections in the translucent mirror increases. In this case, the scene perceived by the optical components appears darker to the user.

[0006] When a transmissive mirror is made of a dielectric multilayer coating, the dielectric multilayer coating has a smaller light absorption rate than a single-layer metal vapor deposition film, thus the light loss in the transmissive mirror can be suppressed.

[0007] However, in dielectric multilayer coatings, the reflectivity of a transmissive mirror varies depending on the incident angle and wavelength of light on the transmissive mirror. Compared to using metal vapor deposition films, the number of manufacturing steps is greater when using dielectric multilayer coatings. Therefore, when using dielectric multilayer coatings, the brightness and hue of the scene perceived by the user change depending on the angle at which the user observes the first surface, and the manufacturing cost of the optical components increases.

[0008] In view of the above, the purpose of this disclosure is to provide an optical component comprising a light guide having an incident surface, a first surface, and a second surface, wherein changes in brightness and hue of an external scene visually recognized through the first surface are suppressed, while light loss on the first surface is reduced.

[0009] According to one aspect of this disclosure, an optical component that internally reflects external light includes a light guide. The light guide has an incident surface to which external light is incident; a first surface, which is the surface to which incident light first reaches from the incident surface, and has a flat portion and a prism portion; and a second surface, arranged opposite to the flat portion. The flat portion totally reflects the incident light toward the second surface. The second surface totally reflects the reflected light from the flat portion toward the first surface. The prism portion has an exit surface that emits a portion of the incident light or a portion of the light reflected from the second surface to the outside.

[0010] The optical component includes a light guide having an incident surface, a first surface from which incident light first arrives, and a second surface opposite to the first surface. The first surface is composed of multiple prism portions and multiple flat portions. The flat portions totally reflect the incident light onto the second surface. The second surface reflects the light reflected by the flat portions back onto the first surface. As a result, the optical component can guide incident light inside the light guide without a translucent mirror, and there is no light absorption caused by a translucent mirror. Furthermore, the light reflectivity in the light guide is independent of the wavelength of the light. Therefore, the optical component has the ability to suppress variations in the brightness and hue of the external scene seen by the user through the first surface while reducing light loss in the light guide.

[0011] The reference numerals attached to components, etc., are examples of the correspondence between components, etc., and specific components, etc., in the embodiments described below. Attached Figure Description

[0012] Figure 1 This is a cross-sectional view showing the optical component according to the first embodiment.

[0013] Figure 2 This is a first explanatory diagram used to illustrate the light guided in the optical component of the first embodiment.

[0014] Figure 3 This is a second explanatory diagram used to illustrate the light guided in the optical component of the first embodiment.

[0015] Figure 4 This is an explanatory diagram used to illustrate the relationship between the width of the flat portion and the prism portion on the first surface and the amount of visible light.

[0016] Figure 5 This is a cross-sectional view showing a modification of the optical component of the first embodiment.

[0017] Figure 6 This is an illustrative diagram used to explain the noise generated in a prism section where the ejection surface and the facing surface are adjacent to each other.

[0018] Figure 7 It is a display Figure 5 An enlarged cross-sectional view of the prism portion in an optical component.

[0019] Figure 8 This is a cross-sectional view showing the optical component according to the second embodiment.

[0020] Figure 9 This is an explanatory diagram illustrating how light is guided in the optical component of the second embodiment.

[0021] Figure 10 This is a cross-sectional view showing a modification of the optical components of the second embodiment.

[0022] Figure 11 This is a cross-sectional view showing the optical component according to the third embodiment.

[0023] Figure 12 This is an explanatory diagram illustrating the light guided in the optical component of the third embodiment.

[0024] Figure 13 This is an explanatory diagram used to illustrate the gaps between light rays on the first surface.

[0025] Figure 14 This is an explanatory diagram illustrating the suppression of gaps in the optical component of the third embodiment.

[0026] Figure 15 This is an explanatory diagram used to illustrate the relationship between the gap and the angle of the inclined surface between the incident surface and the second surface.

[0027] Figure 16 It is a diagram showing the suppression of the gap caused by the angle of the inclined surface between the incident surface and the second surface.

[0028] Figure 17 This is a cross-sectional view showing the fourth surface in the optical component of the third embodiment.

[0029] Figure 18 This is a cross-sectional view showing a modification of the optical components of the third embodiment.

[0030] Figure 19 It is used for explanation Figure 18 An explanatory diagram of the first surface of the optical component.

[0031] Figure 20 This is a cross-sectional view showing the optical component according to the fourth embodiment.

[0032] Figure 21 This is an explanatory diagram illustrating the light guided in the optical component of the fourth embodiment.

[0033] Figure 22 This is an explanatory diagram used to illustrate the relationship between the angle of the inclined surface of the second prism portion of the incident section and the gap between the light rays.

[0034] Figure 23 This is an explanatory diagram used to illustrate the suppression of the gap caused by the angle of the tilted surface of the second prism portion of the incident section.

[0035] Figure 24 This is a cross-sectional view showing the optical component according to the fifth embodiment.

[0036] Figure 25 This is an explanatory diagram used to illustrate the gap created by the width of the incident portion.

[0037] Figure 26 This is an explanatory diagram used to illustrate the light loss caused by the width of the incident portion.

[0038] Figure 27 This is an explanatory diagram used to illustrate the suppression of light loss and gap caused by the width of the incident portion. Detailed Implementation

[0039] In the following description, embodiments of the present disclosure will be illustrated with reference to the accompanying drawings. In the following embodiments, the same reference numerals are assigned to the same or equivalent parts for description.

[0040] (First Embodiment)

[0041] Reference Figures 1 to 4 The optical component 1 of the first embodiment is described. The optical component 1 can be used, for example, as a blind spot assist device attached to a component or obstacle obstructing a user's field of vision, so that the user can visually identify the scene in the blind spot. For example, in the case of vehicle use, the optical component 1 is attached to a pillar of the vehicle and directs external light from the blind spot caused by the pillar to the user, thereby providing a view of the blind spot.

[0042] exist Figure 4 In order to make it easier to understand the light guided in the optical component 1, shadow lines are added to the light to be incident on the optical component 1, the incident light and the light emitted from the optical component 1.

[0043] like Figure 1As shown, the optical component 1 includes a transparent light guide 2, which has an incident surface 2a, a first surface 2b different from the incident surface 2a, and a second surface 2c opposite to the first surface 2b. The first surface 2b has a flat portion 3 and a prism portion 4, and may be composed of the flat portion 3 and the prism portion 4. The light guide 2 also has a third surface 2d connecting the first surface 2b and the second surface 2c. In the optical component 1, as... Figure 2 and Figure 3 As shown, external light L1 is guided from the incident surface 2a inside the light guide 2 and emitted from a first surface 2b, which is different from the incident surface 2a.

[0044] For ease of explanation, the light incident from the incident surface 2a into the light guide 2 will be referred to as "incident light L2", and the light emitted from the prism portion 4 on the first surface 2b will be referred to as "emitted light L3". In addition, the light escaping from the third surface 2d will be referred to as "afterglow L4".

[0045] The light guide 2 is made of a transparent material such as glass, or a resin material such as polyethylene terephthalate, polycarbonate, polyethylene, or acrylic acid. The light guide 2 is designed such that the incident light L2 is totally reflected by the flat portion 3 and the second surface 2c and guided internally. Specifically, the light guide 2 is designed to satisfy formula (1), wherein the constituent material has a refractive index n1, the external medium of the light guide 2 has a refractive index n2 (e.g., in the case of an air layer, n2 = 1), and the incident light L2 has an angle of incidence Ф relative to the flat portion 3 and the second surface 2c.

[0046] Formula (1): sinФ≥n2 / n1

[0047] As a result, even though the light guide 2 does not have a semi-transparent mirror, a portion of the incident light L2 from the incident surface 2a is totally reflected by the flat portion 3 and the second surface 2c and emitted to the outside.

[0048] Specifically, for example, such as Figure 2 As shown, external light L1 is incident on the incident surface 2a of optical component 1 at an incident angle θ1, and is refracted in light guide 2 to become incident light L2, which first reaches the first surface 2b. A portion of the incident light L2 that reaches the flat portion 3 at a guiding angle Φ is totally internally reflected at the interface with the outside and is guided to the second surface 2c without being emitted to the outside. The incident light L2 that has reached the second surface 2c at a guiding angle Φ is totally internally reflected again at the interface with the outside and travels to the first surface 2b. A portion of the light is refracted at the exit surface 4a of prism portion 4 and emitted to the outside at an emission angle θ2; the remaining portion is totally internally reflected by flat portion 3. Additionally, as... Figure 3As shown, for example, a portion of the incident light L2 from the incident surface 2a first reaches the exit surface 4a of the prism portion 4 and is refracted at an emission angle θ2 and emitted to the outside. A portion of the incident light L2 that is repeatedly reflected by the flat portion 3 and the second surface 2c and does not reach the prism portion 4 eventually reaches the third surface 2d, and the afterglow L4 is refracted and emitted to the outside. As described above, the optical component 1 is configured such that emission from the first surface 2b and all internal reflections occur repeatedly within the light guide 2. Therefore, the observation area on the first surface 2b, i.e., the area where the user can visually identify the emitted light L3, can be increased.

[0049] "Incident angle θ1" refers to the angle defined between the incident direction of external light L1 about the incident surface 2a and the normal direction (hereinafter referred to as "normal direction") of the flat surface of the flat portion 3 relative to the first surface 2b. "Guiding angle Ф" is formed between the direction of travel of incident light L2 on the flat portion 3 and the normal direction. Alternatively, "guiding angle Ф" is formed between the direction of travel of incident light L2 on the second surface 2c and the normal direction relative to the second surface 2c. When the flat portion 3 and the second surface 2c are parallel, the guiding angle Ф in the flat portion 3 and the second surface 2c has the same value, regardless of the number of reflections. "Emission angle θ2" refers to the angle formed between the direction of travel of emitted light L3 and the normal direction relative to the flat surface of the flat portion 3, and has the same value as θ1 when the incident surface 2a and the emission surface 4a are parallel to each other. The guiding angle Ф is, for example, the guiding angle based on the maximum incident angle of external light L1 incident on the light guide 2. Figure 4 As shown, the maximum incident angle of external light L1 refers to the angle formed between the normal direction and the virtual straight line connecting the user's eye located near the first surface 2b and the endpoint of the incident surface 2a near the first surface 2b. The above reference is made because external light L1 exceeding the maximum incident angle includes light rays from the area that the user can directly observe without passing through the light guide 2.

[0050] External light L1 is incident on the incident surface 2a of the light guide 2. In this embodiment, the incident surface 2a intersects with the first surface 2b. The incident surface 2a is inclined at an angle ψ relative to the normal direction. That is, in this embodiment, the incident surface 2a is in an inclined state, so that the angle formed with the flat surface becomes an acute angle. Figure 2As shown, the tilt angle ψ of the incident surface 2a relative to the normal direction of the flat portion is smaller than the guiding angle Ф of the incident light L2 relative to the flat portion 3 and the second surface 2c. In this case, if the refraction condition satisfies ψ < π / 2 - Ф, the incident light L2 is refracted along the direction where Ф becomes larger than the incident angle θ1 of the external light L1, and is guided to a wider range than the first surface 2b. Furthermore, the light guide 2 is constructed to satisfy Ф > ψ, because Ф is the angle of total internal reflection, the refractive index of a normal transparent resin material is 1.4 or higher, and since n·sinФ > 1, Ф > 45.3.

[0051] Incident light L2 from incident surface 2a first reaches the first surface 2b of the light guide 2, which has a flat portion 3 and a prism portion 4. In this embodiment, the first surface 2b intersects the incident surface 2a at the prism portion 4, and the flat portion 3 and the prism portion 4 are arranged alternately and repeatedly toward the third surface 2d. The first surface 2b, having the flat portion 3 and the prism portion 4, is formed using a known plastic molding method, such as a mold.

[0052] The second surface 2c is a smooth surface substantially parallel to the first surface 2b. The second surface 2c serves as a reflective surface that totally reflects the incident light L2 reflected by the flat portion 3 back to the first surface 2b. That is, the second surface 2c is a second reflective surface paired with the first reflective surface formed by the flat portion 3 described below.

[0053] The third surface 2d connects the first surface 2b and the second surface 2c, and is, for example, an inclined surface tilted at a predetermined angle. A portion of the incident light L2 that is repeatedly reflected by the flat portion 3 and the second surface 2c and does not reach the prism portion 4 will escape to the outside as afterglow L4 from the third surface 2d. By performing a light-shielding process, such as arranging a light-absorbing film (not shown) on the third surface 2d, the emission of afterglow L4 can be prevented. Thus, noise such as ghosting caused by the leakage of afterglow L4 can be suppressed.

[0054] like Figure 2 and Figure 3As shown, the flat portion 3 serves as a reflective surface that reflects the incident light L2, which has reached the flat portion 3, toward the second surface 2c via total internal reflection. As a result, the light guide 2 can guide the incident light L2 internally without requiring a transmissive mirror made of a metallic or dielectric material. Furthermore, no loss occurs due to the absorption of the incident light L2 in the flat portion 3. The flat portion 3 has a light guiding direction along the flat surface from the incident surface 2a to the third surface 2d, and has a width Ws in the light guiding direction, such that the reflectivity of the incident light L2 on the first surface 2b becomes equal to or higher than a predetermined value. Specifically, the flat portion 3 of the first surface 2b is the reflecting portion of the incident light L2, and the prism portion 4 is the absorbing and emitting portion for the incident light L2. Therefore, the reflectivity Rw of the first surface 2b is determined by the ratio of the flat portion 3. The reflectivity Rw of the first surface 2b is expressed by formula (2), where the width of the prism portion 4 adjacent to the flat portion 3 with width Ws in the light guiding direction is defined as Wp.

[0055] Formula (2): Rw=Ws / (Wp+Ws)

[0056] Preferably, the flat portion 3 satisfies Rw ≥ 0.5, i.e., Wp / Ws ≤ 1. That is, the flat portion 3 has a width Ws such that the reflection of the incident light L2 on the first surface 2b is equal to or greater than the emission of the incident light L2 on the first surface 2b. In this case, the light guide 2 guides more than half of the incident light L2 onto the first surface 2b and emits the emitted light L3 within a range wider than the first surface 2b, thus ensuring the brightness of the emitted light L3.

[0057] Furthermore, when the light guide 2 satisfies formula (1) and the guiding angle Ф is a total reflection angle, the reflectivity Rw of the first surface 2b is determined solely by the ratio of the width of the flat portion 3 to the width of the prism portion 4, as shown in formula (2). That is, in the optical component 1, the reflectivity Rw of the light guide 2 does not depend on the angle or wavelength of the incident light L2. Therefore, the variation in the hue and brightness of the emitted light L3 is suppressed compared to conventional optical components using a semi-transparent mirror.

[0058] The prism portion 4 is arranged adjacent to the flat portion 3 and has an emission surface 4a protruding outward from the flat portion 3 to emit a portion of the incident light L2 to the outside. Figure 1 As shown, the prism portion 4 has a protruding shape, having an ejection surface 4a and a facing surface 4b that faces and intersects the ejection surface 4a. The prism portions 4 are similar to each other.

[0059] The exit surface 4a of the prism portion 4 is substantially parallel to the incident surface 2a. When the exit surface 4a is parallel to the incident surface 2a, the emission angle θ2 of the emitted light L3 from the exit surface 4a is the same as the incident angle θ1, allowing a user located near the first surface 2b to visually identify the same ray as the external light L1 due to the optical component 1. The case where the incident surface 2a and the exit surface 4a are parallel includes the case where the incident surface 2a and the exit surface 4a are substantially parallel due to, for example, unavoidable errors in the manufacturing precision of the light guide 2. The term "substantially parallel" in this specification also applies hereafter.

[0060] like Figure 2 As shown, the facing surface 4b of the prism portion 4 is inclined at an angle δ relative to the normal direction and intersects with the emission surface 4a. The facing surface 4b is covered by a light-absorbing film 5, and both the reflection of incident light L2 on the facing surface 4b and the intrusion of external light from the first surface 2b are suppressed. As a result, noise such as ghosting caused by the overlap between emitted light L3 and external light from the first surface 2b is suppressed. Furthermore, noise caused by unintentional reflection of incident light L2 from the facing surface 4b and emission from the emission surface 4a can be suppressed. The light-absorbing film 5 is made of any light-shielding resin material, metal material, etc., and is formed by any process such as printing or vapor deposition.

[0061] The tilt angle δ of the facing surface 4b is greater than or equal to the emission angle θ2 of the emitted light L3. When the incident surface 2a and the exiting surface 4a are parallel, the tilt angle δ is greater than or equal to the incident angle θ1 of the external light L1. As a result, the emitted light L3 is emitted to the outside without being blocked by the facing surface 4b. In addition, it is preferable that the tilt angle δ of the facing surface 4b is smaller than the guiding angle Ф in the flat portion 3. As a result, it is possible to suppress the incident light L2 from entering the facing surface 4b and interfering with it, and it is possible to suppress unintentional reflection of the incident light L2 on the facing surface 4b and noise caused by reflection.

[0062] When the width Ws of the flat portion 3 and the width Wp of the prism portion 4 are both the same, a gap corresponding to the prism width Wp is formed between the reflected rays. If the relationship between the gap and the prism portion 4 in the rear portion changes periodically, uneven brightness, i.e., moiré fringes, may occur. From the viewpoint of suppressing such moiré fringes, it is preferable that Ws and Wp have values ​​within a predetermined range centered on a certain value, i.e., have a distribution. For example, the width Ws of the flat portion 3 in the light guiding direction is preferably within a predetermined range expressed by the following formula, in which the number of flat portions 3 on the first surface 2b is k1, and the average value Wsa is the center value.

[0063]

[0064] The width Wp of the prism portion 4 in the light guiding direction is preferably within a predetermined range represented by the following formula, in which the number of prism portions 4 on the first surface 2b is k2, and the average value Wpa is the center value.

[0065]

[0066] The predetermined range of Ws and Wp is, for example, ±10% of the center value. Because the values ​​of Ws and Wp are distributed in this way, gaps between reflected rays in the flat portion 3 and the periodic relationship between the subsequent prism portion 4 can be avoided, and the occurrence of moiré fringes can be suppressed. Furthermore, Ws and Wp can be located within the predetermined range from the center value as described above, and their values ​​can be appropriately changed. Additionally, k1 and k2 are, for example, natural numbers of 2 or greater.

[0067] Since the emitted light L3 is emitted only from the exit surface 4a of the prism portion 4 at an emission angle θ2 on the first surface 2b, the emitted light L3 reaching the user is as follows: Figure 4 The image shows a light and dark pattern with a period equal to the sum of the width Wp of the prism portion 4 and the width Ws of the flat portion 3. The pitch P of the emitted light L3 in the user's viewing direction... E It is represented by formula (3).

[0068] Formula (3): P E =(Wp+Ws)cosθ2

[0069] Preferably, the widths Ws and Wp of the adjacent flat portions 3 and prism portions 4 are designed such that the pitch P of the emitted light L3 is such that... E Less than 2mm. This is because the minimum pupil diameter in a bright location is 2mm or larger. When the pitch P of the emitted light L3... E When the value is less than 2 mm, the amount of emitted light L3 that is visually recognized by the user is averaged, and the change in brightness / darkness is suppressed when the user's viewpoint moves.

[0070] The flat portion 3 and the second surface 2c do not necessarily have to be perfectly parallel, depending on the distance between the blind spot area that the user wants to visually identify.

[0071] Specifically, when the flat portion 3 is parallel to the second surface 2c, the guiding angle Φ of the incident light L2 is constant and independent of its position within the light guide 2, thus the emission angle θ2 of the emitted light L3 is constant. Since the emitted light L3 with the same emission angle θ2 also enters the user's eye, this is the same as light entering the eye from infinity, even if the user's viewpoint is different. That is, when the blind spot area identified by the user's vision is located at a predetermined distance from the user or further (e.g., tens to hundreds of meters), it is preferable that the flat portion 3 and the second surface 2c are parallel to each other.

[0072] When one of the flat portion 3 and the second surface 2c is slightly tilted relative to the other, the guiding angle Φ of the incident light L2 changes according to its position in the light guide 2. In this state, since the emission angle θ2 of the emitted light L3 varies according to the user's viewpoint position, it is the same as when light enters the human eye from a finite distance below a predetermined distance, such as several meters to tens of meters. That is, when the blind spot area to be visually identified by the user is located at a finite distance less than or equal to the predetermined distance from the user, it is preferable that the flat portion 3 and the second surface 2c are not parallel. In this case, the distance between the flat portion 3 and the second surface 2c, which are facing each other, increases with distance from the incident surface 2a. If the flat portion 3 and the second surface 2c are arranged close to each other, the emitted light L3 is emitted in a direction away from each other, and binocular fusion cannot be achieved.

[0073] According to this embodiment, the first surface 2b, where the incident light L2 from the incident surface 2a first reaches, has a flat portion 3 and a prism portion 4. Therefore, the optical component 1 can guide the incident light L2 without a translucent mirror. As a result, compared to conventional optical components with translucent mirrors, the manufacturing process can be simplified and manufacturing costs can be reduced. Furthermore, since the light guide 2 is configured such that the incident light L2 undergoes total internal reflection through the flat portion 3 and the second surface 2c facing the flat portion 3, light absorption loss in the light guide 2 is suppressed. Additionally, since the reflectivity Rw of the incident light L2 on the first surface 2b is determined by the ratio of the width Ws of the adjacent flat portions 3 to the width Wp of the prism portion 4, the reflectivity Rw is independent of the wavelength and angle of the incident light L2. Therefore, the optical component 1 of this embodiment can suppress changes in the brightness and hue of the external scene visually perceived by the user through the first surface 2b, while also suppressing light loss in the light guide 2.

[0074] (Modification of the first embodiment)

[0075] like Figure 5 As shown, in optical component 1, a portion of prism portion 4 may have a top side 4c connecting the emitting surface 4a and the facing surface 4b. In this case, the light-absorbing film 5 is arranged to cover the top side 4c instead of the facing surface 4b.

[0076] In this modification, except for the prism portion 4 closest to the incident surface 2a, the prism portion 4 has a trapezoidal shape, having an exiting surface 4a, a facing surface 4b, and a top side 4c. The prism portions 4 are arranged at the same height from the flat portion 3 to the top side 4c in the normal direction. The top side 4c of the prism portions 4 is positioned at the same height as the apex of the prism portion 4 closest to the incident surface 2a (the intersection between the exiting surface 4a and the facing surface 4b). In the prism portion 4, the top side 4c is parallel to the second surface 2c.

[0077] In the prism section 4, even if the incident light L2 is incident on the facing surface 4b and reflected on the facing surface 4b, the reflected light is also guided to the top side 4c and shielded by the light absorption film 5.

[0078] Specifically, such as Figure 6 As shown, when the exiting surface 4a and the facing surface 4b intersect adjacent to each other, if the incident light L2 is incident on the facing surface 4b, the incident light L2 is reflected by the facing surface 4b, and the reflected light can be emitted from the exiting surface 4a. When the incident light L2 directly reaches the exiting surface 4a, this light is emitted as the emitted light L... 3a It is emitted. If the emitted light L 3a The reflected light on the surface 4b and the emitted light L emitted from the exiting surface 4a are the same as the reflected light on the surface 4b. 3b Overlapping will generate noise. Even if the facing surface 4b is tilted at an angle δ (< the guide angle Ф), the difference between the guide angle Ф and the tilt angle δ is usually about 10°, and it is difficult to provide an angle difference greater than 10°. Furthermore, if incident light L2 with an incident angle close to 90° is incident on the facing surface 4b, it is difficult to completely suppress interface reflection and shield the reflected light with the light absorption film 5. In this case, the reflected light escapes from the exiting surface 4a to the outside. As a result, when the exiting surface 4a and the facing surface 4b intersect adjacent to each other, it may be impossible to suppress the generation of noise caused by the facing surface 4b.

[0079] Conversely, when the prism portion 4 has a trapezoidal shape, since the top side 4c exists between the exiting surface 4a and the facing surface 4b, the tilt angle of the facing surface 4b deviates significantly from the guiding angle Ф. As a result, even if the incident light L2 is incident on and reflected at the facing surface 4b, the reflected light is guided towards the top side 4c and will not reach the exiting surface 4a, thus preventing the emitted light L2 from being affected by the exiting surface 4a. 3b The noise caused.

[0080] like Figure 7 As shown, in prism section 4, the angle ε formed between the normal direction and the virtual straight line VL1 connecting points V and P is greater than the emission angle θ2 of the emitted light L3. Point V is the first endpoint of the emitting surface 4a of a certain prism section 4 adjacent to the flat portion 3, and point P is the second endpoint of the top side 4c of another prism section 4 adjacent to the ...

[0081] This modification also provides an optical component 1 that has the same effect as the first embodiment. Furthermore, since the prism portion 4 has a trapezoidal shape containing a top side 4c, it is possible to obtain an effect that prevents noise from being generated due to the reflection of incident light L2 on the facing surface 4b of the prism portion 4.

[0082] (Second Embodiment)

[0083] Reference Figure 8 and Figure 9 The optical component 1 of the second embodiment is described. Figure 9 In order to easily understand the light guided in optical component 1, a portion of external light L1 and incident light L2 are shown. 21 To L 23 and emitted light L 31 To L 33 And add shadows to the light.

[0084] In the optical component 1 of this embodiment, as Figure 8 As shown, the first surface 2b has three regions 2ba, 2bb, and 2bc, and the width ratio of the adjacent flat portion 3 to the prism portion 4 differs among regions 2ba, 2bb, and 2bc. This difference from the first embodiment will be primarily described in this embodiment.

[0085] In this embodiment, the first surface 2b is sequentially divided from the incident surface 2a into, for example, a first region 2ba, a second region 2bb, and a third region 2bc, and the width ratio of adjacent flat portions 3 and prism portions 4 differs between regions 2ba, 2bb, and 2bc. Specifically, in the first region 2ba, the width of the flat portion 3 is W. S1 And the width of prism part 4 is W P1 In the second region 2bb, the width of the flat portion 3 is W. S2 And the width of prism part 4 is W P2 Value W S1 / W P1 Greater than W S2 / W P2 The third region 2bc consists only of the prism portion 4, and the width of the flat portion 3 is zero relative to the width of the prism portion 4. In the first surface 2b, the ratio of the width of the flat portion 3 to the width of the prism portion 4, i.e., Ws / Wp, is smaller in the region far from the incident surface 2a.

[0086] In other words, the width of the flat portion 3 is larger in the region near the incident surface 2a, and its width is zero in the region furthest from the incident surface 2a, i.e., no flat portion is arranged there. The prism portion 4 has a similar shape and can have the same width and height in each region, or it can have different widths and heights in each region. Furthermore, in regions 2ba to 2bc, each of the width Ws of the flat portion 3 and the width Wp of the prism portion 4 is within a predetermined range centered on a constant value (e.g., an average value expressed by Formula 1 or Formula 2), as in the first embodiment. As a result, the generation of moiré fringes caused by the periodic structure of the flat portion 3 and the prism portion 4 can be suppressed. In addition, since the structural period of each region is different, the generation of moiré fringes can be suppressed even when the width Ws of the flat portion 3 and the width Wp of the prism portion 4 are constant values ​​in each region.

[0087] Here, the effect obtained by the first surface 2b, composed of multiple regions with different Ws / Wp values, will be described. For example, as Figure 9 As shown, as a typical example, external light L1 is incident on light guide 2 and reflected twice by the flat portion 3.

[0088] For ease of explanation, the portion of the incident light L2 from the incident surface 2a until it first reaches the flat portion 3 will be referred to as "incident light L". 21 The incident light L reflected by the flat part 3. 21 A portion is called "incident light L". 22 The incident light L reflected by the flat part 3. 22 A portion is called "incident light L". 23 "The incident light L emitted from prism section 4" 21 A portion is called "emitting light L" 31 "The incident light L emitted from prism section 4" 22 A portion is called "emitting light L" 32 "The incident light L emitted from prism section 4" 23 A portion is called "emitting light L" 33 ".

[0089] As in the first embodiment, when the width ratio of adjacent flat portions 3 and prism portions 4 is the same throughout the entire region of the first surface 2b, the reflectivity Rw is constant, thus the amount of incident light L2 decreases at a constant rate with increasing reflection count. For example, when the reflectivity Rw equals 0.6 and the incident light L2... 21 When defined as 100%, the incident light L 22 The amount is 100 × 0.6 = 60%, and the emitted light L 31 The amount is 100-60=40%. In addition, the incident light L... 23The amount is 60 × 0.6 = 36%, and the emitted light L 32 The amount is 60-36=24%. Incident light L 23 The amount of reflected light is 36 × 0.6 = 21.6%, and the emitted light L 33 The amount is 36-21.6=14.4%. When the value Ws / Wp is constant as described above, the amount of emitted light L3 decreases with the increase of the number of reflections, making the position of the incident surface 2a, which is far from the first surface 2b, appear darker.

[0090] Conversely, according to this embodiment, the first surface 2b is composed of multiple regions with different Ws / Wp values, and the reflectivity Rw of each region is different. For example, the first surface 2b is configured such that the reflectivity Rw of the first region 2ba is 2 / 3, the reflectivity Rw of the second region 2bb is 1 / 2, and the reflectivity Rw of the third region 2bc is 0. In this case, when the incident light L... 21 When defined as 100%, the incident light L 22 It is approximately 67% (100 × 2 / 3), and the emitted light L 31 It is approximately 33% (100-67). Additionally, the incident light L... 23 The value is 67 × 1 / 2 ≈ 34%, and the emitted light L 32 It is approximately 33% (67-34≈33%). Incident light L 23 All light is emitted in the third region 2bc, thus emitting light L. 33 Approximately 33%. Thus, when the first surface 2b is composed of multiple regions with different Ws / Wp values, i.e., different reflectivities Rws, it is possible to emit light L... 31 To L 33 The amount of light is averaged to ensure that there is a uniform amount of light. Therefore, it is possible to reduce brightness unevenness caused by the user's viewpoint position.

[0091] The first surface 2b is not limited to being composed of three regions 2ba to 2bc, but can also be composed of two or more regions. For example, when the maximum number of reflections of the incident light L2 on the second surface 2c is m (m: a natural number greater than or equal to 1), the first surface 2b is composed of (m+1) regions. In this case, the Ws / Wp value decreases from the first region adjacent to the incident surface 2a to the (m+1) region, and will be zero in the (m+1) region. For example, when the first surface 2b is composed of four regions, the reflectivity Rw in the first region is 3 / 4, the reflectivity Rw in the second region is 2 / 3, the reflectivity Rw in the third region is 1 / 2, and the reflectivity Rw in the fourth region is 0. Therefore, when the first surface 2b is divided into four regions, the light intensity of emitted light L3 in the first region is 100×(1-3 / 4)=25%, the light intensity of emitted light L3 in the second region is 75×(1-2 / 3)=25%, the light intensity of emitted light L3 in the third region is 50×(1-1 / 2)=25%, and the light intensity of emitted light L3 in the fourth region is the remaining 25%. As described above, when the first surface 2b consists of (m+1) regions, the Wsk / (Wpk+Wsk) of the k-th region is represented by Wsk / (Wpk+Wsk)=(m+1-k) / (m+2-k), making the amount of emitted light L3 uniform across the regions. Note that k is an integer greater than or equal to or less than m, and the reflectivity in the (m+1) region is 0.

[0092] According to this embodiment, in addition to the same effect as in the first embodiment, the amount of emitted light on the first surface 2b is averaged, and the optical component 1 has the effect of ensuring brightness.

[0093] (Modification of the second embodiment)

[0094] like Figure 10 As shown, except for the prism portion 4 closest to the incident surface 2a and the prism portion 4 furthest from the incident surface 2a in the third region 2bc, the prism portion 4 in the second embodiment can be a trapezoidal shape with a top side 4c. The trapezoidal prism portion 4 has a top side 4c between the exiting surface 4a and the facing surface 4b, and the top side 4c is covered by a light-absorbing film 5, as in the modification of the first embodiment. Furthermore, the top side 4c can be parallel to the second surface 2c and at the same height as the apex of the other prism portion 4 that does not have a top side 4c. As a result, the trapezoidal prism portion 4 suppresses noise caused by the reflection of the incident light L2 on the facing surface 4b. In regions where the prism portions 4 are adjacent to each other, it is difficult to form a sufficiently wide top side 4c on the prism portion 4, so only the prism portion 4 adjacent to the flat portion 3 has a trapezoidal shape with a top side 4c.

[0095] According to this modification, the optical component 1 has the same effect as the second embodiment, and also has the effect of suppressing noise generation in the area with the trapezoidal prism portion 4.

[0096] (Third Embodiment)

[0097] Reference Figures 11 to 16 The optical component 1 of the third embodiment is described. Figure 13 and Figure 14 In order to make it easier to understand the light guided in the optical component 1, the external light L1, the incident light L2, and the emitted light L3 are represented by shaded lines.

[0098] In the optical component 1 of this embodiment, as Figure 11 As shown, unlike the first embodiment, the light guide 2 has a fourth surface 6 located between the incident surface 2a and the second surface 2c, and the fourth surface 6 protrudes from the second surface 2c. This difference will be mainly described in this embodiment.

[0099] In this embodiment, the light guide 2 has a fourth surface 6 connecting the incident surface 2a and the second surface 2c, and the fourth surface 6 has a shape that protrudes outward from the second surface 2c. Height To is the distance between the second surface 2c and the flat portion 3 in the normal direction of the flat portion. Height Td is the distance between the end of the incident surface 2a adjacent to the fourth surface 6 and the flat portion 3 in the normal direction. The light guide 2 is constructed to satisfy the relationship Td > To.

[0100] In this embodiment, as Figure 12 As shown, due to the fourth surface 6, the area of ​​the incident surface 2a of the light guide 2 is increased compared to the embodiment described above. Therefore, because the area of ​​the incident light L2 from the incident surface 2a reaching the first surface 2b for the first time is increased, the light guide 2 is able to guide more light. Consequently, gaps between the guided light rays do not occur.

[0101] Reference Figure 13 Describe the "gap between light rays". If the light guide 2 does not have a fourth surface 6, and the incident surface 2a intersects the second surface 2c adjacent to each other, for example, as... Figure 13 As shown, the emitted light L3 is emitted in a state where it is separated from the flat portion 3 and the prism portion 4. The large gap GAP1 between the emitted light L3 passing through the flat portion 3 and the prism portion 4 is the "gap between light rays," and the external light L1 guided here cannot be visually recognized by the user. That is, if there is a gap between the guided light rays, the continuity of the external light L1 on the first surface 2b cannot be ensured, that is, the continuity displayed to the user.

[0102] Conversely, in the optical component 1 of this embodiment, the light guide 2 has a fourth surface 6, and the height Td of the incident surface 2a is greater than the height To of the second surface 2c. As a result, as... Figure 14 As shown, the incident light L2 reaches the wide area of ​​the first surface 2b and is reflected by the flat portion 3. Therefore, the area of ​​the second surface 2c that the incident light L2 first reaches also increases. Therefore, there will be no gap between the area of ​​the first surface 2b that the incident light L2 first reaches and the area of ​​the first surface 2b that the incident light L2 reaches again after being reflected by the flat portion 3 and the second surface 2c. As a result, as... Figure 14 As shown, the emitted light L3 is emitted from all the prism portions 4 of the first surface 2b, and no gaps are created between the light rays. Therefore, the optical component 1 according to this embodiment does not create gaps between light rays and ensures display continuity.

[0103] The fourth surface 6 is covered with a light-absorbing film 5 to suppress noise such as ghosting caused by unintentional intrusion of external light and interface reflection. Specifically, when light rays with an angle smaller than the incident angle θ1 are incident on the incident surface 2a, a portion of the light rays reaches the fourth surface 6. The light-absorbing film 5 absorbs the light reaching the fourth surface 6 in such a way that unintentional light, such as light reflected in a portion different from the second surface 2c, is directed toward the first surface 2b. Therefore, the generation of noise such as ghosting is limited.

[0104] like Figure 11 As shown, the fourth surface 6 is an inclined surface that linearly connects the end of the incident surface 2a and the end of the second surface 2c. The fourth surface 6 is designed such that the inclination angle ξ relative to the normal direction does not create a "light gap" in the guidance of the incident light L2 from the incident surface 2a.

[0105] Specifically, such as Figure 15 As shown, when the tilt angle ξ of the fourth surface 6 is greater than the guiding angle Ф of the incident light L2, gaps may appear between the light rays.

[0106] For ease of explanation, the end of the incident surface 2a adjacent to the second surface 2c will be referred to as the "first end 2aa", and a portion of the incident light incident from near the first end 2aa will be referred to as the "incident light L". 2a Furthermore, the end of the second surface 2c adjacent to the incident surface 2a is referred to as the "second end 2ca", and a portion of the incident light reflected near the second end 2ca is referred to as the "incident light L". 2b ".

[0107] When the tilt angle ξ of the fourth surface 6 is greater than the guiding angle Ф, the incident light L 2a By passing a position away from the second end 2ca, and the incident light L 2aThe incident light L reflected near the second end 2ca 2b There is a gap between them. Incident light L 2a and incident light L 2b The gap between them is called the "gap between light rays". When a gap between light rays is created, the incident light L2 may not reach a portion of the prism portion 4 on the first surface 2b. In this case, a gap is created between the light rays, and the continuity of the display cannot be guaranteed.

[0108] Therefore, the fourth surface 6 is constructed to satisfy the condition that the tilt angle ξ is less than the guiding angle Ф. In this case, as... Figure 16 As shown, the incident light L 2a It passes near the second end 2ca and is incident on light L. 2a With incident light L 2b There are no gaps between them. As a result, the light guide 2 does not have gaps between light rays, that is, gaps between the guided light rays, and the optical component 1 can ensure the display continuity on the first surface 2b.

[0109] Furthermore, in the fourth surface 6, when the incident angle θ1 of the external light L1 varies with θ1±Δθ1 and the guiding angle Ф of the incident light L2 varies with Ф±ΔФ, the gap between the light rays can be suppressed within the range of θ1±Δθ1 when the tilt angle ξ<Ф-ΔФ is satisfied.

[0110] In the above description, the fourth surface 6 is an inclined surface, and as a typical example, the inclination angle ξ is smaller than the guiding angle Ф. However, the fourth surface 6 is not limited to the single inclined surface described above, and may also have multiple surfaces or curved surfaces. For example, as Figure 17 As shown, the fourth surface 6 can have a rectangular shape containing two surfaces. When the fourth surface 6 has a structure other than a tilted surface, the shape is not particularly restricted while the incident light L2 incident from near the first end 2aa passes near the second end 2ca. Specifically, as Figure 16 and 17 As shown, the tilt angle ξ is formed by the virtual straight line VL2 connecting the first end 2aa and the second end 2ca and the normal direction. Therefore, the fourth surface 6 can have any shape while satisfying ξ < Ф, but the region from the first end 2aa to the second end 2ca is covered by the light-absorbing film 5.

[0111] The incident surface 2a preferably has a tilt angle ψ less than π / 2 - θ1. When the incident surface 2a of the refracted external light L1 satisfies ψ < π / 2 - θ1, the guiding angle Ф of the refracted incident light L2 becomes greater than the incident angle θ1 of the external light L1. As a result, compared with the case where the guiding angle is assumed to be θ1, the light guide 2 is constructed such that the initial arrival width of the incident light L2 is wider, while the guiding width, i.e., the height To of the second surface 2c, can be limited.

[0112] According to this embodiment, in addition to having the same effects as the first embodiment, the optical component 1 also has the effects of preventing gaps between the guided light and ensuring the continuity of the display on the first surface 2b.

[0113] (Modification of the third embodiment)

[0114] like Figure 18 As shown, in the optical component 1 of the third embodiment, the first surface 2b has a prism region 2bp consisting only of the prism portion 4. Furthermore, the third surface 2d is an inclined surface continuous with the exit surface 4a of the prism portion 4 closest to the third surface 2d. In other words, the third surface 2d is the end surface of the light guide 2 and, together with the exit surface 4a, is parallel to the incident surface 2a.

[0115] like Figure 19 As shown, the light guide 2 has a width La in the light guiding direction, and the first surface 2b extending from the end adjacent to the incident surface 2a to the prism region 2bp has a width Lb in the light guiding direction. The light guide 2 is constructed to satisfy formulas (4) and (5).

[0116] Formula (4): La=(2N-1)×To×tanФ

[0117] Formula (5): Lb=2N×To×tanФ

[0118] In formulas (4) and (5), N is a positive integer. When the light guide 2 satisfies formulas (4) and (5), the end of the incident light L2 that reaches the second surface 2c due to repeated reflection on the first surface 2b ( Figure 19 L in 22 The light guide 2 coincides with the upper end surface of the third surface 2d. As a result, only the light reflected by the second surface 2c is incident on the third surface 2d, while the light reflected by the first surface 2b is not incident on the third surface 2d. That is, the emitted light from the third surface 2d is emitted only toward the first surface 2b, but not toward the second surface 2c. Therefore, the light guide 2 can emit guided light in the user's viewing direction without any waste.

[0119] Furthermore, in addition to satisfying formulas (4) and (5), by setting the portion of the first surface 2b beyond La as the prism region 2bp, all incident light L2 that has reached the prism region 2bp can be emitted in the user's viewing direction. That is, the number of prism portions 4 in the region beyond La can be minimized, and the length of the light guide 2 in the light guiding direction can be reduced.

[0120] The value La can be within ±10% of the value expressed as (2N-1)×To×tanФ. Furthermore, Lb can be within ±10% of the value expressed as 2N×To×tanФ. This is because a deviation of approximately 10% may occur depending on the angle of the incident light. When each of La and Lb is within the aforementioned range, the effect of minimizing the loss of the guiding light is expected.

[0121] According to this modification, in addition to having the effects of the third embodiment, the optical component 1 also has the effect of suppressing the loss of the guiding light. Furthermore, in the optical component 1, the length of the light guide 2 in the light guiding direction is minimized.

[0122] (Fourth Embodiment)

[0123] Reference Figures 20 to 23 The optical component 1 of the fourth embodiment is described. Figure 22 and Figure 23 In the diagram, external light L1 and incident light L2 are represented by shading. A portion of external light L1 incident on the light guide 2 and a portion of external light L1 not incident on the light guide 2 are represented by different shading.

[0124] like Figure 20 As shown, the optical component 1 of this embodiment has an incident portion 8 composed of a plurality of second prism portions 7. The incident portion 8 is the outer surface connecting the first surface 2b and the second surface 2c of the light guide 2, and is opposite to the third surface 2d. This difference from the first embodiment will be mainly described in this embodiment.

[0125] In this embodiment, the light guide 2 has an incident portion 8, which is a region located between the first surface 2b and the second surface 2c and on the opposite side of the third surface 2d. The incident portion 8 is composed of a second prism portion 7, while the prism portion 4 on the first surface 2b is referred to as the "first prism portion".

[0126] The second prism portion 7 is shaped to have a first surface 7a corresponding to the incident surface 2a and a second surface 7b that intersects adjacent to the first surface 7a. The second prism portions 7 are adjacent to each other and arranged parallel to each other along the direction connecting the first surface 2b and the second surface 2c.

[0127] For ease of explanation, the direction connecting the first surface 2b and the second surface 2c will be referred to as the "prism arrangement direction". The second prism portion 7 is arranged in the prism arrangement direction.

[0128] like Figure 21 As shown, the second prism portion 7 has an angle ω formed between the prism arrangement direction and the normal direction of the flat portion, and the angle ω is less than or equal to the guide angle Ф.

[0129] In the second prism section 7, the first surface 7a is substantially parallel to the ejection surface 4a of the first surface 2b. For example... Figure 21 As shown, the first surface 7a has an angle ψ that forms with the normal direction, and this angle ψ is, for example, set to be the same as the tilt angle of the incident surface 2a in various embodiments.

[0130] In the second prism portion 7, an angle σ is formed between the plane of the second surface 7b and the normal direction. Angle σ is greater than or equal to the incident angle θ1 of the external light L1 and less than or equal to the guiding angle Ф of the incident light L2. That is, it is preferable to satisfy θ1≤σ≤Ф in order to limit the formation of gaps between the light rays incident from the first surface 7a.

[0131] Specifically, when σ < θ1, such as Figure 22 As shown, the light ray L1 incident from the first surface 7a of the second prism portion 7 reaches the position between the vertex and the valley of the second prism portion 7 and escapes to the outside. Furthermore, since a portion of the external light ray L1 is blocked by adjacent second prism portions 7, the external light ray L1 does not reach the entire area of ​​the first surface 7a except for the second prism portion 7 located closest to the first surface 2b. As a result, the incident light L1 from the first surface 7a of a certain second prism portion 7... 2a A gap is created between the incident light L2b from the first surface 7a of the second prism portion 7 adjacent to that second prism portion 7. In this case, because a gap is created in the incident light from the first surface 7a and the periodic light rays reach the first surface 2b, moiré fringes may occur.

[0132] When θ1≤σ≤Ф is satisfied, such as Figure 23 As shown, a portion of the external light L1 is incident from the first surface 7a of a certain second prism portion 7 and reaches the area between the vertices and valleys of the second prism portion 7 to escape to the outside. However, when θ1≤σ≤Ф is satisfied, the proportion of light escaping to the outside is smaller compared to the case where σ<θ1 is satisfied. Furthermore, the external light L1 reaches the entire area of ​​the first surface 7a of the second prism portion 7 without being blocked by adjacent second prism portions 7. As a result, the incident light L2a from a certain second prism portion 7 and the incident light L from an adjacent second prism portion 7... 2b There are no gaps between them, and they can suppress the occurrence of moiré fringes.

[0133] like Figure 23 As shown, when the height of the second prism part 7 in the normal direction is h and ω=Ф is satisfied, the maximum height of the incident part 8 in the normal direction is To+h.

[0134] According to this embodiment, the optical component 1 has the same effect as in the first embodiment.

[0135] (Fifth Embodiment)

[0136] The optical component 1 of the fifth embodiment will be referred to Figures 24 to 27 Describe it. In Figures 25 to 27 In order to make it easy to understand the light guided in the optical component 1, a portion of the external light L1, the incident light L2, and the emitted light L3 are shown and represented by shadows.

[0137] In the optical component 1 of this embodiment, as Figure 24 As shown, the light guide 2 has an incident portion 8 adjacent to the second surface 2c. Both the incident portion 8 and the second surface 2c are arranged opposite to the first surface 2b. The difference between this embodiment and the first embodiment is that the light guide 2 has a fifth surface 2e connecting the incident portion 8 and the first surface 2b. This difference will be mainly described in this embodiment.

[0138] In this embodiment, the light guide 2 has an incident portion 8, and the prisms are arranged along the surface formed by the second surface 2c. A fifth surface 2e is defined between the incident portion 8 and the first surface 2b. Similar to the fourth embodiment, the incident portion 8 is composed of second prism portions 7 arranged adjacent to each other and parallel to each other. Furthermore, in the second prism portions 7, the first surface 7a is substantially parallel to the exiting surface 4a on the first surface 2b.

[0139] In this embodiment, the incident portion 8 has a configuration in which the valley of the second prism portion 7 lies on the plane formed by the second surface 2c. That is, in the incident portion 8, the virtual plane formed by the valley of the second prism portion 7 is arranged parallel to the flat portion 3. As a result, the optical path length of the light rays that first reach the first surface 2b from the incident portion 8 is always the same, regardless of the position of the incident portion 8. Therefore, the distortion of the external scene visually perceived by the user through the emitted light L3 is minimized. When the incident light L2 incident from the incident portion 8 is reflected by the flat portion 3 and reaches the second surface 2c, the length of the optical path is constant. When the incident light L2 reflected by the second surface 2c reaches the first surface 2b, the length of the optical path is constant.

[0140] The incident portion 8 has a width W in the light guiding direction. I Furthermore, from the viewpoint of minimizing the gap between light rays on the first surface 2b while suppressing light loss, the width W is preferred. I It satisfies formula (6).

[0141] Formula (6): W I =2To×tanФ

[0142] When W I When <2To×tanФ, such as Figure 25As shown, the area of ​​the first surface 2b that the incident light L2 first reaches from the incident portion 8 becomes smaller. As a result, a gap GAP2 is generated between the emitted light L3 that first reaches the first surface 2b and the emitted light L3 that reaches the first surface 2b after being reflected once by the flat portion 3 and the second surface 2c.

[0143] When W I When >2To×tanФ, such as Figure 26 As shown, the area of ​​the first surface 2b that the incident light L2 first reaches from the incident portion 8 increases. Therefore, there is no gap between the guided light rays. However, since the area of ​​the second surface 2c that the reflected light reaches becomes larger, a portion of the light initially reflected by the first surface 2b reaches the incident portion 8. Since the incident portion 8 does not have a reflective surface facing the first surface 2b, when the incident light L2 from the first surface 2b reaches the incident portion 8, the light is transmitted to the outside. Therefore, when W I When the value is greater than 2To×tanФ, light loss will occur because a portion of the light escapes from the incident part 8 to the outside.

[0144] When W I When = 2To × tanФ, as Figure 27 As shown, in the light guide 2, the area of ​​the first surface 2b that the incident light L2 first reaches from the incident portion 8 increases, while the reflected light only reaches the second surface 2c. As a result, no gap is created between the emitted light L3 emitted from the first surface 2b while being separated by the flat portion 3 and the prism portion 4. This suppresses light loss from the incident portion 8. Since a deviation of approximately 10% can occur depending on the angle of the incident light, if W I Within ±10% of the value represented by 2To×tanФ, light loss can be reduced, and the effects of gaps can be minimized.

[0145] According to this embodiment, the optical component 1 has the same effect as in the first embodiment. Furthermore, the incident portion 8 and the first surface 2b are substantially parallel to each other, and the length of the optical path within the light guide 2 is constant, regardless of the position of the incident portion 8. Therefore, the optical component 1 is not affected by the arrangement of the light guide 2. For example, even if the light guide 2 rotates around a direction other than the normal direction, light rays incident horizontally to the incident portion 8 are still emitted horizontally from the first surface 2b. Therefore, the optical component 1 is not affected by arrangements such as the mounting posture of the light guide 2.

[0146] (Other embodiments)

[0147] Although this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and modifications within the equivalent scope. Furthermore, various combinations and patterns, and furthermore, other combinations and patterns including only one of these elements, or above or below, are also included within the scope or concept of this disclosure.

[0148] In the third to fifth embodiments, a portion of the prism portion 4 along the first surface 2b may have a trapezoidal shape defining a top side 4c. Furthermore, in the fourth and fifth embodiments, the first surface 2b may have multiple regions where the ratio of the width Ws of the flat portion 3 to the width Wp of the prism portion 4 is different. As described above, the optical component 1 is not limited to each embodiment and its modifications, and can be freely combined unless they are obviously incompatible.

Claims

1. An optical member comprising: a light guide having an incident surface on which external light is incident; a first surface having a plurality of flat portions and a plurality of prism portions, incident light incident from the incident surface reaching the first surface for the first time, and a second surface disposed opposite the plurality of flat portions, wherein the plurality of flat portions are first reflecting surfaces to totally reflect the incident light toward the second surface, the second surface is a second reflecting surface to totally reflect reflected light reflected by the flat portions toward the first surface, the plurality of prism portions have an emission surface to emit a portion of the incident light or a portion of light reflected by the second surface to the outside, the first surface has a plurality of regions, a ratio of a width of the flat portions to a width of the prism portions adjacent to each other being different between the plurality of regions, and as the plurality of regions are located farther from the incident surface, the ratio of the width of the flat portions to the width of the prism portions is smaller, and the width of the flat portions is zero in a region farthest from the incident surface.

2. The optical member according to claim 1, wherein an incident angle of the incident light with respect to a flat surface formed by the plurality of flat portions and an incident angle of light reflected by the flat portions with respect to the second surface are defined as Φ, a refractive index of the light guide is defined as n1, a refractive index of a medium in contact with the light guide is defined as n2, and the light guide satisfies a relation of sin Φ > n2 / n1.

3. The optical member according to claim 2, wherein an angle between an incident direction of the external light on the incident surface and a normal direction with respect to the flat portions is defined as θ1, an angle between the incident surface and the normal direction is defined as ψ, and the light guide satisfies relations of Φ > θ1 and π / 2 - Φ > ψ.

4. The optical member according to claim 1, wherein the plurality of prism portions disposed on the first surface are first prism portions, the light guide has an incident portion having a plurality of second prism portions, and the incident surface is an outer surface of each of the plurality of second prism portions and is parallel to the emission surface of the first prism portions.

5. The optical member of claim 4, wherein, the incident portion is disposed on a plane formed by the second surface.

6. The optical member according to claim 1, wherein a normal direction is defined with respect to a flat surface formed by the flat portions, an end point of the incident surface opposite the first surface is defined as a first end portion, a distance in the normal direction between the first end portion and the flat surface is defined as a height Td, a distance in the normal direction between the flat portions and the second surface is defined as a height To, the incident surface satisfies a relation of Td > To, an end point of the second surface adjacent to the incident surface is defined as a second end portion, an angle formed between the normal direction and a virtual straight line connecting the first end portion and the second end portion is defined as ξ, the second end portion is disposed farther from the first end portion as the first end portion is located farther from the incident surface, and the light guide satisfies a relation of ξ > π / 2 - Φ. an angle of incidence of the incident light with respect to the flat surface is defined as Ф, and the light guide satisfies a relationship of ξ < Ф.

7. The optical member of claim 6, wherein, the light guide is covered with a light-absorbing film in a region from the first end portion to the second end portion.

8. The optical member according to claim 1, wherein a number of the plurality of regions is defined as m + 1 (m: a natural number of 1 or more), in a kth (1≤k≤m) region from the incident surface among the plurality of regions, a width of the prism portion is defined as Wpk, and a width of the flat portion is defined as Wsk, and the kth region satisfies a relationship of Wsk / (Wpk+Wsk)=(m+1-k) / (m+2-k).

9. The optical member of any one of claims 1-8, wherein, the plurality of flat portions are parallel to the second surface.

10. The optical member of any one of claims 1-8, wherein, the exit surface is parallel to the incident surface.

11. The optical member according to any one of claims 1 to 8, wherein a width of the prism portion is defined as Wp, and a width of the flat portion adjacent to the prism portion is defined as Ws, an angle formed between an incident direction of the external light on the incident surface and a normal direction with respect to a flat surface formed by the flat portion is defined as θ1, and the first surface satisfies a relationship of pf(Wp+Ws)cosθ1<2mm.

12. The optical member according to any one of claims 1 to 8, wherein the prism portion has a facing surface facing the exit surface, an angle formed between the facing surface and a normal direction with respect to a flat surface formed by the flat portion is defined as δ, an angle formed between emitted light emitted outward from the exit surface and the normal direction is defined as θ2, and the facing surface satisfies a relationship of δ≥θ2.

13. The optical member of any one of claims 1-8, wherein, at least a part of the prism portion has a trapezoidal shape having a top side adjacent to the exit surface.

14. The optical member according to claim 13, wherein each of the prism portions has a trapezoidal shape with a top side, one of the prism portions has a first end point which is an end point of the exit surface adjacent to the flat portion, another prism portion adjacent to the one of the prism portions has a second end point which is an end point of the top side opposite to the exit surface, an angle formed by a virtual straight line connecting the first end point and the second end point and a normal direction with respect to a flat surface formed by the flat portion is ε, an angle formed by emitted light emitted outward from the exit surface and the normal direction is θ2, and the prism portion having the trapezoidal shape satisfies a relationship of ε>θ2.

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