JP7466132B2 - Optical system, lighting system, display system and mobile object - Google Patents

Description

The present disclosure generally relates to optical systems, lighting systems, display systems, and moving bodies. More specifically, the present disclosure relates to optical systems, lighting systems, display systems, and moving bodies that control light incident on an entrance surface and emit it from an exit surface.

Patent Document 1 discloses an image display device (display system) that projects a virtual image into a target space. This image display device is an automobile HUD (Head-Up Display) device. Projected light, which is image light emitted from an automobile HUD device (optical system) inside the dashboard, is reflected by the windshield and directed toward the driver, who is the viewer. This allows the user (driver) to view images such as navigation images as virtual images, and the user (driver) views the virtual image as if it were superimposed on a background such as the road surface.

JP 2017-142491 A

The present disclosure aims to provide an optical system, a lighting system, a display system, and a moving body that can easily extract light uniformly from the entire area of the emission surface.

An optical system according to an aspect of the present disclosure includes a light guide member, a prism, and a light control body. The light guide member has an incident surface on which light is incident, and a first surface and a second surface opposed to each other. The second surface of the light guide member is an exit surface of the light. The prism is provided on the first surface and reflects light passing through the inside of the light guide member toward the second surface. The light control body is located between a light source and the incident surface. The light control body controls light output from the light source and incident on the incident surface. The light guide member includes a direct optical path that directly reflects the light incident from the incident surface at the prism and outputs it from the second surface. The optical axis of the light incident from the incident surface is inclined with respect to the first surface so that the distance to the first surface becomes smaller as the optical axis moves away from the incident surface. The light control body has a shape conversion function that converts a shape projected on a projection surface parallel to the incident surface from a first shape of the light output from the light source to a second shape of the light incident on the incident surface. The light control body includes an incident lens. The entrance lens has a primary entrance surface and a secondary entrance surface. The primary entrance surface is arranged to face the light source. The secondary entrance surface is located at least partially around the primary entrance surface and is oriented toward a normal to the primary entrance surface. The optical axis of the light source is inclined with respect to the normal to the primary entrance surface.
An optical system according to an aspect of the present disclosure includes a light guide member, a prism, and a light control body. The light guide member has an incident surface on which light is incident, and a first surface and a second surface opposed to each other. The second surface of the light guide member is an exit surface of the light. The prism is provided on the first surface and reflects light passing through the inside of the light guide member toward the second surface. The light control body is located between a light source and the incident surface. The light control body controls light output from the light source and incident on the incident surface. The light guide member includes a direct optical path that directly reflects the light incident from the incident surface at the prism and causes it to exit from the second surface. The optical axis of the light incident from the incident surface is inclined with respect to the first surface so that the distance to the first surface becomes smaller as the optical axis moves away from the incident surface. The light control body has a shape conversion function that converts a shape projected on a projection surface parallel to the incident surface from a first shape of the light output from the light source to a second shape of the light incident on the incident surface. The light control body has a plurality of lens surfaces on a surface facing the light source.
An optical system according to an aspect of the present disclosure includes a light guide member, a prism, and a light control body. The light guide member has an incident surface on which light is incident, and a first surface and a second surface opposed to each other. The second surface of the light guide member is an exit surface of the light. The prism is provided on the first surface and reflects light passing through the inside of the light guide member toward the second surface. The light control body is located between a light source and the incident surface. The light control body controls light output from the light source and incident on the incident surface. The light guide member includes a direct optical path that directly reflects the light incident from the incident surface at the prism and outputs it from the second surface. The optical axis of the light incident from the incident surface is inclined with respect to the first surface so that the distance to the first surface becomes smaller as the optical axis moves away from the incident surface. The light control body has a shape conversion function that converts a shape projected on a projection surface parallel to the incident surface from a first shape of the light output from the light source to a second shape of the light incident on the incident surface. An inclination angle of a surface of the light control body facing the light source with respect to an axis facing the light source varies in a circumferential direction about the axis.
An optical system according to an aspect of the present disclosure includes a light guide member, a prism, and a light control body. The light guide member has an incident surface on which light is incident, and a first surface and a second surface opposed to each other. The second surface of the light guide member is an exit surface of the light. The prism is provided on the first surface and reflects light passing through the inside of the light guide member toward the second surface. The light control body is located between a light source and the incident surface. The light control body controls light output from the light source and incident on the incident surface. The light guide member includes a direct optical path that directly reflects the light incident from the incident surface at the prism and outputs it from the second surface. The optical axis of the light incident from the incident surface is inclined with respect to the first surface so that the distance to the first surface becomes smaller as the optical axis moves away from the incident surface. The light control body has a shape conversion function that converts a shape projected on a projection surface parallel to the incident surface from a first shape of the light output from the light source to a second shape of the light incident on the incident surface. The surface of the light control body facing the light source has an asymmetric shape in one direction perpendicular to an axis facing the light source.
An optical system according to an aspect of the present disclosure includes a light guide member, a prism, and a light control body. The light guide member has an incident surface on which light is incident, and a first surface and a second surface opposed to each other. The second surface of the light guide member is an exit surface of the light. The prism is provided on the first surface and reflects light passing through the inside of the light guide member toward the second surface. The light control body is located between a light source and the incident surface, and controls light output from the light source and incident on the incident surface. The light guide member includes a direct optical path that directly reflects the light incident from the incident surface at the prism and causes it to exit from the second surface. The optical axis of the light incident from the incident surface is inclined with respect to the first surface so that the distance to the first surface decreases as the light axis moves away from the incident surface. The light control body includes an incident lens. The incident lens has a main incident surface and a secondary incident surface. The main incident surface is arranged to face the light source. The secondary incident surface is located in at least a part of the periphery of the main incident surface and is oriented toward the normal to the main incident surface. The secondary incidence surface has a first lens surface and a second lens surface, the first lens surface having a greater inclination angle with respect to the normal to the primary incidence surface than the second lens surface having a greater inclination angle with respect to the normal to the primary incidence surface.

An illumination system according to one aspect of the present disclosure includes the optical system and a light source that outputs light incident on the incident surface.

A display system according to one aspect of the present disclosure includes the lighting system and a display that receives light emitted from the lighting system and displays an image.

A mobile body according to one aspect of the present disclosure includes the display system and a mobile body on which the display system is mounted.

The present disclosure has the advantage that it is easy to extract light uniformly from the entire area of the exit surface.

Fig. 1A is a cross-sectional view showing an overview of an optical system according to embodiment 1. Fig. 1B is a schematic enlarged view of an area A1 in Fig. 1A. FIG. 2 is a conceptual diagram showing an outline of a light control unit of the optical system. FIG. 3 is a perspective view showing an outline of the optical system. FIG. 4 is an explanatory diagram of a display system using the above optical system. FIG. 5 is an explanatory diagram of a moving body equipped with the above-mentioned display system. Fig. 6A is a plan view of the optical system, Fig. 6B is a front view of the optical system, Fig. 6C is a bottom view of the optical system, and Fig. 6D is a side view of the optical system. Fig. 7A is a schematic diagram showing an enlarged area A1 of Fig. 6C, and Fig. 7B is a cross-sectional view taken along line B1-B1 of Fig. 7A. Fig. 8A is a perspective view showing the shape of the light control body of the same, Fig. 8B is a cross-sectional view taken along line B1-B1 in Fig. 8A, and Fig. 8C is a cross-sectional view taken along line C1-C1 in Fig. 8A. 9A and 9B are explanatory diagrams showing the light intensity distribution of the light control unit according to the embodiment of the present invention and a comparative example, respectively; 10A and 10B are explanatory diagrams showing the light intensity distribution of the light controller according to the embodiment of the present invention and a comparative example, respectively; 11A and 11B are explanatory diagrams showing the light intensity distribution when the light guide member is viewed from one side in the thickness direction in a case where light is emitted from the light control body to the light guide member according to the embodiment of the present invention, respectively. Fig. 12A is an explanatory diagram showing a light beam passing through the inside of the light control body of the above embodiment. Fig. 12B is an explanatory diagram showing a light beam passing through the inside of a light control body according to a comparative example. Fig. 12C is an explanatory diagram showing a light beam passing through the inside of a light control body according to another comparative example. Fig. 13A is a side view showing an overview of an optical system according to a first modified example, Fig. 13B is a schematic enlarged view of an area A1 in Fig. 13A, and Fig. 13C is a schematic enlarged view of an area A2 in Fig. 13A. 14A and 14B are side and cross-sectional views illustrating an overview of an optical system according to a second modified example. FIG. 15 is a front view showing an overview of a light control unit according to a third modified example. Fig. 16A is an explanatory diagram of an illumination system using an optical system according to a fourth modified example, and Fig. 16B is a schematic enlarged view of an area A1 in Fig. 16A. Fig. 17A is a plan view of a main part showing an example of an optical system according to the fifth modified example, and Fig. 17B is a plan view of a main part showing another example of an optical system according to the fifth modified example. Fig. 18A is a schematic diagram showing an example of a prism according to the sixth modified example, and Fig. 18B is a schematic diagram showing another example of a prism according to the sixth modified example. 19A and 19B are schematic diagrams showing still another example of a prism according to the sixth modified example; 20A and 20B are schematic diagrams showing still another example of a prism according to the sixth modified example; Fig. 21A is a schematic diagram showing an example of a prism according to the seventh modified example, Fig. 21B is a schematic diagram showing another example of a prism according to the seventh modified example, and Fig. 21C is a schematic diagram showing yet another example of a prism according to the seventh modified example. Fig. 22A is a bottom view showing an overview of an optical system according to embodiment 2. Fig. 22B is a schematic enlarged view of a first region of the optical system. Fig. 22C is a schematic enlarged view of a mixed region of the optical system. Fig. 22D is a schematic enlarged view of a second region of the optical system.

(Embodiment 1)
(1) Overview First, an overview of an optical system 100 according to the present embodiment and an illumination system 200 using the optical system 100 will be described with reference to FIGS. 1A to 3. FIG.

The optical system 100 according to this embodiment (see Figs. 1A and 1B) has a function of controlling light incident on the entrance surface 10 and emitting it from the exit surface (second surface 12). As shown in Figs. 1A and 1B, the optical system 100 includes a light guide member 1, a light control body 2, and a prism 3.

The optical system 100 and the light source 4 constitute the lighting system 200. In other words, the lighting system 200 according to this embodiment includes the optical system 100 and the light source 4. The light source 4 outputs light incident on the incident surface 10. As will be described in detail later, when the optical system 100 includes the light control body 2, the light from the light source 4 does not directly enter the light-guiding member 1, but enters the light-guiding member 1 through the light control body 2. In other words, the light source 4 emits light to the incident surface 10 (of the light-guiding member 1) through the light control body 2.

Thus, in this embodiment, the optical system 100 further includes a light control body 2 in addition to the light guide member 1 and the prism 3. The light control body 2 is located between the light source 4 and the incident surface 10 of the light guide member 1, and controls the light output from the light source 4 and incident on the incident surface 10. In particular, in this embodiment, the light guide member 1 and the light control body 2 are integrated as an integrally molded product. That is, in this embodiment, the light guide member 1 and the light control body 2 are integrally molded products and are inseparably integrated. In other words, the light control body 2 is seamlessly continuous with respect to the incident surface 10 of the light guide member 1, and the light guide member 1 and the light control body 2 are seamlessly integrated. Therefore, in this embodiment, the incident surface 10 of the light guide member 1 is a "virtual surface" defined inside the integrally molded product of the light guide member 1 and the light control body 2, and does not have a real entity.

In this embodiment, the light guide member 1 has an incident surface 10 on which light is incident, and a first surface 11 and a second surface 12 that face each other. The second surface 12 is the light exit surface. The prism 3 is provided on the first surface 11. The prism 3 reflects light that passes through the inside of the light guide member 1 toward the second surface 12.

Here, the light guide member 1 includes a direct optical path L1 (see Figures 1A and 1B). The direct optical path L1 is an optical path that causes the light incident from the incident surface 10 to be directly reflected by the prism 3 and emitted from the second surface 12. More specifically, the light guide member 1 includes an optical path (direct optical path L1) that causes the light that enters the light guide member 1 from the incident surface 10 to be emitted from the second surface 12 inside the light guide member 1 with only one reflection at the prism 3. When the light passing through the direct optical path L1 enters the light guide member 1 from the incident surface 10, it is not reflected anywhere other than by the prism 3, but reaches the second surface 12 with only one reflection at the prism 3, and is emitted directly to the outside of the light guide member 1 from the second surface 12.

In this embodiment, most of the light that enters the light-guiding member 1 from the incident surface 10 and exits from the second surface 12 is guided inside the light-guiding member 1 through the direct optical path L1. Therefore, in this embodiment, most of the light that enters the light-guiding member 1 from the incident surface 10 is not reflected anywhere other than by the prism 3, and is reflected only once by the prism 3 before being emitted outside the light-guiding member 1 from the second surface 12.

In the optical system 100 according to this embodiment, as shown in FIG. 1A, the optical axis Ax1 of the light incident from the incident surface 10 is inclined with respect to the first surface 11 so that the distance to the first surface 11 decreases the further away from the incident surface 10. That is, in this embodiment, the optical axis Ax1 of the light incident from the incident surface 10 is not parallel but inclined with respect to the first surface 11, and due to this inclination, the optical axis Ax1 approaches the first surface 11 the further away from the incident surface 10.

As a result, the light incident from the incident surface 10 approaches the first surface 11 as it moves away from the incident surface 10, that is, as it travels inside the light-guiding member 1, and is more likely to be incident on the first surface 11 (including the prism 3). Therefore, most of the light incident from the incident surface 10 is more likely to be incident on the first surface 11 before reaching the end surface 13 of the light-guiding member 1 that faces the incident surface 10. In other words, most of the light incident from the incident surface 10 is less likely to reach the end surface 13 of the light-guiding member 1 that is opposite the incident surface 10, so light is less likely to leak from the end surface 13. As a result, it is easier to increase the proportion of light emitted from the second surface 12 to the outside of the light-guiding member 1 through the direct optical path L1 to the light incident from the incident surface 10, and the light extraction efficiency can be improved.

In the optical system 100 according to this embodiment, as shown in FIG. 2, the light control body 2 has a shape conversion function. The shape conversion function is a function of converting the shape projected on the projection surface S1 parallel to the incident surface 10 from the first shape F1 of the light output from the light source 4 to the second shape F2 of the light incident on the incident surface 10. Here, the projection surface S1 is a "virtual surface" defined inside the light control body 2 and does not have a real body. In this embodiment, as an example, the projection surface S1 is the same surface as the incident surface 10. That is, in this embodiment, the shape of the light projected on the projection surface S1 (incident surface 10) parallel to the incident surface 10 is converted from the first shape F1 to the second shape F2 by the light control body 2 located between the light source 4 and the incident surface 10 of the light guide member 1.

This makes it possible to control the range of the light incident from the incident surface 10 inside the light-guiding member 1, regardless of the first shape F1, which is the shape of the light output from the light source 4. In other words, the range of the light incident from the incident surface 10 inside the light-guiding member 1 is due to the second shape F2, which is the shape of the light incident on the incident surface 10, and the optical system 100 can convert the shape from the first shape F1 to the second shape F2. Therefore, according to this optical system 100, it is possible to control the light incident from the incident surface 10 so that the light reaches a relatively wide range inside the light-guiding member 1. As a result, in the optical system 100, it becomes easier for the light to reach the entire area of the first surface 11, and it becomes easier to extract the light uniformly from the entire area of the second surface 12, which is the exit surface.

In addition, in the optical system 100 according to this embodiment, as shown in FIG. 3, at least one of the first surface 11 and the second surface 12 has a light distribution control unit 14. The light distribution control unit 14 controls the light distribution of the light extracted from the second surface 12. As an example in this embodiment, of the first surface 11 and the second surface 12, only the second surface 12 has the light distribution control unit 14. In other words, the light distribution control unit 14 is provided on the second surface 12.

As a result, the light distribution of the light extracted from the second surface 12 of the light guide member 1 can be controlled by the light distribution control unit 14 provided in the light guide member 1. In particular, the light guide member 1 includes a direct light path L1 that causes the light incident into the light guide member 1 from the incident surface 10 to be emitted from the second surface 12 inside the light guide member 1 with only one reflection at the prism 3. In other words, after the light passing through the direct light path L1 enters the light guide member 1 from the incident surface 10, it is not reflected by anything other than the prism 3, and is only reflected once by the prism 3, and is emitted to the outside of the light guide member 1 from the second surface 12. Therefore, the shapes of the first surface 11 and the second surface 12 do not contribute to the light guide inside the light guide member 1, and even if the light distribution control unit 14 is provided in the light guide member 1, the light guide performance of the light guide member 1 is not easily deteriorated. As a result, while enabling light distribution control, light can be efficiently extracted from the second surface 12 to the outside of the light guide member 1 through the direct light path L1, and the light extraction efficiency can be improved.

2, the optical element 20 used as the light control body 2 in the optical system 100 according to this embodiment includes an input lens 21 and an output section 22. The optical element 20 outputs the light incident on the input lens 21 from the light source 4 from the output section 22. The input lens 21 has a main input surface 211 and a secondary input surface 212. The main input surface 211 is arranged to face the light source 4. The secondary input surface 212 is directed to the normal line L21 of the main input surface 211. The secondary input surface 212 is located in at least a part of the periphery of the main input surface 211. The optical axis Ax2 of the light source 4 is inclined with respect to the normal line L21 of the main input surface 211. Here, the normal line L21 of the main input surface 211 is, for example, a normal line of the main input surface 211 at the tip (the apex of the dome) if the main input surface 211 is dome-shaped. The normal L21 of the main incidence surface 211 is a "virtual line" and has no physical entity.

As a result, the optical axis Ax2 of the light source 4 is inclined with respect to the normal line L21 of the main incidence surface 211, so that the light from the light source 4 is incident on the incidence lens 21 of the optical element 20 in an asymmetric manner with respect to the normal line L21 of the main incidence surface 211. Therefore, it is possible to disrupt the balance of the light intensity incident from the light source 4 on the main incidence surface 211 of the incidence lens 21 and the secondary incidence surfaces 212 located around it. As a result, it is possible to improve the light capture efficiency of the optical element 20.

(2) Details Hereinafter, the optical system 100 according to this embodiment, the illumination system 200 using the optical system 100, the display system 300 using the illumination system 200, and the moving body B1 will be described in detail with reference to FIGS. 1A to 12C.

(2.1) Premise In the following description, the width direction of the light guiding member 1 (the direction in which the multiple light sources 4 are arranged in FIG. 3) is referred to as the "X-axis direction", and the depth direction of the light guiding member 1 (the direction in which the optical axis Ax1 extends in FIG. 1A) is referred to as the "Y-axis direction". In addition, in the following description, the thickness direction of the light guiding member 1 (the direction in which the first surface 11 and the second surface 12 are arranged in FIG. 1A) is referred to as the "Z-axis direction". The X-axis, Y-axis, and Z-axis that define these directions are mutually orthogonal. The arrows indicating the "X-axis direction", "Y-axis direction", and "Z-axis direction" in the drawings are merely indicated for the purpose of explanation and do not have any substance.

In addition, the term "extraction efficiency" in this disclosure refers to the ratio of the amount of light exiting from the second surface 12 (exit surface) of the light guide member 1 to the amount of light entering the entrance surface 10 of the light guide member 1. In other words, the light extraction efficiency becomes higher (larger) when the relative ratio of the amount of light exiting from the second surface 12 of the light guide member 1 to the amount of light entering the entrance surface 10 of the light guide member 1 becomes larger. As an example, if the amount of light entering the entrance surface 10 of the light guide member 1 is "100" and the amount of light exiting from the second surface 12 of the light guide member 1 is "10", the light extraction efficiency of the light guide member 1 is 10%.

In addition, in this disclosure, "capture efficiency" refers to the ratio of the amount of light captured by the optical element 20 (light control body 2) to the amount of light output from the light source 4. In other words, if the relative ratio of the amount of light captured by the optical element 20 to the amount of light output from the light source 4 increases, the light capture efficiency will be higher (larger). As an example, if the amount of light output from the light source 4 is "100" and the amount of light captured by the optical element 20 is "10", the light capture efficiency of the optical element 20 will be 10%.

In addition, the term "optical axis" in this disclosure refers to a virtual light ray that is representative of the light flux passing through the entire system. As an example, the optical axis Ax2 of the light source 4 coincides with the axis of rotational symmetry of the light emitted from the light source 4.

In addition, in this disclosure, "parallel" refers to two things being approximately parallel, that is, two things being strictly parallel, and also to a relationship in which the angle between the two things is within a range of a few degrees (e.g., less than 5 degrees).

In addition, in this disclosure, "orthogonal" refers to a relationship in which the two are approximately orthogonal, i.e., the two are strictly orthogonal, and the angle between the two is within a range of a few degrees (e.g., less than 5 degrees) of 90 degrees.

(2.2) Display System First, the display system 300 will be described with reference to FIGS.

As shown in FIG. 4, the lighting system 200 according to this embodiment constitutes the display system 300 together with the display unit 5. In other words, the display system 300 according to this embodiment includes the lighting system 200 and the display unit 5. The display unit 5 receives light emitted from the lighting system 200 and displays an image. The "image" here refers to an image displayed in a manner that is visible to the user U1 (see FIG. 5), and may be a figure, symbol, letter, number, design, photograph, or the like, or a combination of these. Images displayed on the display system 300 include videos (moving images) and still images (still images). Furthermore, "video" includes an image composed of multiple still images obtained by stop motion photography or the like.

As shown in FIG. 5, the display system 300 according to this embodiment constitutes a mobile body B1 such as an automobile together with a mobile body B11. In other words, the mobile body B1 according to this embodiment includes the display system 300 and the mobile body B11. The mobile body B11 is equipped with the display system 300. As an example in this embodiment, the mobile body B1 is an automobile (passenger car) driven by a person. In this case, the user U1 who views the image displayed on the display system 300 is a passenger of the mobile body B1, and as an example in this embodiment, it is assumed that the driver of the automobile serving as the mobile body B1 is the user U1.

In this embodiment, the display system 300 is used, for example, in a head-up display (HUD) mounted on the mobile body B1. The display system 300 is used, for example, to display driving assistance information related to the speed information, condition information, driving information, etc. of the mobile body B1 in the field of view of the user U1. Driving information of the mobile body B1 includes, for example, navigation-related information that displays the driving route, etc., and information related to ACC (Adaptive Cruise Control) that keeps the driving speed and following distance constant.

As shown in Figures 4 and 5, the display system 300 includes an image display unit 310, an optical system 320, and a control unit 330. The display system 300 further includes a housing 340 that houses the image display unit 310, the optical system 320, and the control unit 330.

The housing 340 is made of, for example, a synthetic resin molded product. The image display unit 310, the optical system 320, the control unit 330, etc. are housed in the housing 340. The housing 340 is attached to the dashboard B13 of the mobile body B11. Light reflected by the second mirror 322 (described later) of the optical system 320 is emitted to a reflecting member (windshield B12) through an opening on the top surface of the housing 340, and the light reflected by the windshield B12 is focused in the eye box C1. The reflecting member is not limited to the windshield B12, and may be realized, for example, by a combiner or the like arranged on the dashboard B13 of the mobile body B11.

According to such a display system 300, the user U1 visually recognizes a virtual image projected in the space in front of the moving body B1 (outside the vehicle) through the windshield B12. In this disclosure, the "virtual image" refers to an image that is formed as if an object actually exists by the divergent light rays when the light emitted from the display system 300 diverges on a reflective member such as the windshield B12. Therefore, the user U1 who is driving the moving body B1 visually recognizes an image as a virtual image projected by the display system 300 superimposed on the real space spreading in front of the moving body B1. In short, the display system 300 according to this embodiment displays a virtual image as an image. The images (virtual images) that the display system 300 can display include a virtual image E1 superimposed along the running surface D1 of the moving body B1, and a virtual image drawn three-dimensionally along a plane PL1 perpendicular to the running surface D1.

The image display unit 310 includes a case 311. The image display unit 310 has a function of displaying a stereoscopic image by a light field method that reproduces light emitted in multiple directions from an object in an image to make the object appear stereoscopic. However, the method in which the image display unit 310 stereoscopically displays a virtual image of a stereoscopically drawn object is not limited to the light field method. The image display unit 310 may adopt a parallax method in which images having parallax with each other are projected onto the left and right eyes of the user U1, respectively, to allow the user U1 to view a virtual image of a stereoscopically drawn object.

The image display unit 310 includes a display 5 and an illumination system 200 including an optical system 100. The display 5 is, for example, a liquid crystal display or the like, and displays an image upon receiving light emitted from the illumination system 200. In other words, the illumination system 200 emits light toward the display 5 from behind the display 5, and the light from the illumination system 200 passes through the display 5, causing the display 5 to display an image. In other words, the illumination system 200 functions as a backlight for the display 5.

The image display unit 310 includes a case 311. The case 311 houses an illumination system 200 including the optical system 100 and the light source 4, and a display 5. The illumination system 200 and the display 5 are held in the case 311. Here, the display 5 is arranged along the upper surface of the case 311, and one surface of the display 5 is exposed from the upper surface of the case 311. The illumination system 200 is arranged below the display 5 inside the case 311, and outputs light from below the display 5 toward the display 5. As a result, the upper surface of the case 311 forms a display surface 312 on which an image is displayed.

The image display unit 310 is housed inside the housing 340 with the display surface 312 facing the first mirror 321 (described later). The display surface 312 of the image display unit 310 has a shape (e.g., rectangular) that matches the range of the image to be projected onto the user U1, i.e., the shape of the windshield B12. A plurality of pixels are arranged in an array on the display surface 312 of the image display unit 310. The plurality of pixels of the image display unit 310 emit light in response to the control of the control unit 330, and an image is displayed on the display surface 312 by the light output from the display surface 312 of the image display unit 310.

The image displayed on the display surface 312 of the image display unit 310 is emitted to the windshield B12, and the light reflected by the windshield B12 is focused in the eye box C1. In other words, the image displayed on the display surface 312 is viewed by the user U1, whose viewpoint is within the eye box C1, through the optical system 320. At this time, the user U1 views a virtual image projected into the space in front of the moving body B1 (outside the vehicle) through the windshield B12.

The optical system 320 focuses the light output from the display surface 312 of the image display unit 310 into the eye box C1. In this embodiment, the optical system 320 includes, for example, a first mirror 321 which is a convex mirror, a second mirror 322 which is a concave mirror, and a windshield B12.

The first mirror 321 reflects the light output from the image display unit 310 and makes it incident on the second mirror 322. The second mirror 322 reflects the light incident from the first mirror 321 towards the windshield B12. The windshield B12 reflects the light incident from the second mirror 322 and makes it incident on the eye box C1.

The control unit 330 includes, for example, a computer system. The computer system is mainly composed of one or more processors and one or more memories as hardware. The functions of the control unit 330 (for example, the functions of the drawing control unit 331, the image data creation unit 332, and the output unit 333, etc.) are realized by the one or more processors executing a program recorded in one or more memories or storage units 334 of the computer system. The program is pre-recorded in one or more memories or storage units 334 of the computer system. The program may be provided through an electric communication line, or may be provided by recording it on a non-transitory recording medium such as a memory card, optical disk, or hard disk drive that can be read by the computer system.

The storage unit 334 is realized by a non-transitory recording medium such as a rewritable non-volatile semiconductor memory. The storage unit 334 stores programs and the like executed by the control unit 330. As already mentioned, the display system 300 is used to display driving assistance information related to the speed information, condition information, driving information, and the like of the moving body B1 in the field of view of the user U1. For this reason, the type of virtual image displayed by the display system 300 is determined in advance. The storage unit 334 stores image data for displaying virtual images (virtual image E1, which is an object of planar drawing, and virtual image E1, which is an object of three-dimensional drawing).

The drawing control unit 331 receives detection signals from various sensors 350 mounted on the moving body B1. The sensors 350 are sensors for detecting various information used, for example, in an advanced driver assistance system (ADAS). The sensors 350 include, for example, at least one of a sensor for detecting the state of the moving body B1 and a sensor for detecting the state around the moving body B1. The sensors for detecting the state of the moving body B1 include, for example, sensors for measuring the vehicle speed, temperature, remaining fuel, etc. of the moving body B1. The sensors for detecting the state around the moving body B1 include an image sensor for photographing the surroundings of the moving body B1, a millimeter wave radar, or LiDAR (Light Detection and Ranging), etc.

The drawing control unit 331 acquires one or more image data for displaying information related to the detection signal input from the sensor 350 from the storage unit 334 based on the detection signal. Here, when multiple types of information are to be displayed on the image display unit 310, the drawing control unit 331 acquires multiple image data for displaying the multiple types of information. Furthermore, the drawing control unit 331 determines position information related to the position at which the virtual image is to be displayed in the target space based on the detection signal input from the sensor 350. Then, the drawing control unit 331 outputs the image data and position information of the virtual image to be displayed to the image data creation unit 332.

The image data creation unit 332 creates image data for displaying a virtual image of the display target based on the image data and position information input from the drawing control unit 331.

The output unit 333 outputs the image data created by the image data creation unit 332 to the image display unit 310, and causes the display surface 312 of the image display unit 310 to display an image based on the created image data. The image displayed on the display surface 312 is projected onto the windshield B12, causing the display system 300 to display an image (virtual image). In this way, the image (virtual image) displayed by the display system 300 is visually recognized by the user U1.

(2.3) Optical System Next, the optical system 100 will be described with reference to FIGS. 1A to 3 and 6A to 7B.

In this embodiment, the optical system 100 includes a light-guiding member 1, a plurality of light control bodies 2, and a plurality of prisms 3. That is, the optical system 100 according to this embodiment includes a plurality of light control bodies 2, and further includes a plurality of prisms 3.

In addition, in this embodiment, the optical system 100 and the multiple light sources 4 constitute the illumination system 200. That is, the illumination system 200 according to this embodiment includes the optical system 100 and the multiple light sources 4.

The multiple light control bodies 2 have a common configuration, and therefore, unless otherwise specified below, the configuration described for one light control body 2 is also the same for the other light control bodies 2. Furthermore, the multiple prisms 3 have a common configuration, and therefore, unless otherwise specified below, the configuration described for one prism 3 is also the same for the other prisms 3. Furthermore, the multiple light sources 4 have a common configuration, and therefore, unless otherwise specified below, the configuration described for one light source 4 is also the same for the other light sources 4.

The light source 4 is, for example, a solid-state light-emitting element such as a light-emitting diode (LED) element or an organic electro-luminescence (OEL) element. In this embodiment, as an example, the light source 4 is a chip-shaped light-emitting diode element. In reality, such a light source 4 emits light from its surface (light-emitting surface) with a certain area, but ideally, it can be considered as a point light source that emits light from a single point on its surface. Therefore, in the following, the light source 4 will be described assuming that it is an ideal point light source.

In this embodiment, as shown in FIG. 2, the light source 4 is disposed so as to face the incident surface 10 of the light guide member 1 at a predetermined distance. The light control body 2 is located between the light source 4 and the incident surface 10 of the light guide member 1.

In this embodiment, the light control body 2 is integral with the light guide member 1. In this disclosure, "integral" refers to a mode in which multiple elements (parts) can be physically handled as one unit. In other words, multiple elements being integral means that multiple elements are integrated into one and can be handled as one member. In this case, the multiple elements may be in an inseparable integral relationship, such as an integrally molded product, or multiple elements created separately may be mechanically joined by, for example, welding, adhesion, or crimping. In other words, the light guide member 1 and the light control body 2 may be integrated in an appropriate manner.

More specifically, in this embodiment, as described above, the light guide member 1 and the light control body 2 are integrated as an integrally molded product. In other words, in this embodiment, the light guide member 1 and the light control body 2 are an integrally molded product and are inseparably integrated. Therefore, as described above, the incident surface 10 of the light guide member 1 is a "virtual surface" defined inside the integrally molded product of the light guide member 1 and the light control body 2, and does not have a physical entity.

The multiple light sources 4 are arranged in a line at a predetermined interval in the X-axis direction, as shown in FIG. 3. The multiple light sources 4 correspond one-to-one with the multiple light control bodies 2. In other words, the multiple light control bodies 2 are also arranged in a line in the X-axis direction, just like the multiple light sources 4. Here, the pitch of the multiple light sources 4 in the X-axis direction is equal to the pitch of the multiple light control bodies 2.

The light guide member 1 is a member that takes in light from the light source 4 from the entrance surface 10 into the light guide member 1 and guides the light through the light guide member 1 to the second surface 12, which is the exit surface, that is, guides the light. In this embodiment, as an example, the light guide member 1 is a molded product made of a translucent resin material such as acrylic resin, and is formed into a plate shape. In other words, the light guide member 1 is a light guide plate with a certain thickness.

As described above, the light guide member 1 has an incident surface 10 through which light is incident, and a first surface 11 and a second surface 12 (exit surface) that face each other. Furthermore, the light guide member 1 has an end surface 13 that faces the incident surface 10.

Specifically, in this embodiment, as shown in Figures 6A to 6D, the light guide member 1 is a rectangular plate, and two surfaces facing each other in the thickness direction of the light guide member 1 are the first surface 11 and the second surface 12. Furthermore, one of the four end surfaces (circumferential surfaces) of the light guide member 1 is the incident surface 10. In other words, the light guide member 1 is formed in a rectangular shape in a plan view (seen from one side in the Z-axis direction). Here, as an example, the light guide member 1 is formed in a rectangular shape with a smaller dimension in the Y-axis direction than in the X-axis direction. Then, both sides of the light guide member 1 in the thickness direction (Z-axis direction) respectively constitute the first surface 11 and the second surface 12. Furthermore, both sides of the light guide member 1 in the short side direction (Y-axis direction) respectively constitute the incident surface 10 and the end surface 13.

Thus, one of the two end faces (the left face in FIG. 1A) of the light-guiding member 1 facing each other in the Y-axis direction is the incident face 10 into which the light emitted from the multiple light sources 4 enters through the multiple light control bodies 2. The two faces of the light-guiding member 1 facing each other in the Z-axis direction are the first face 11 and the second face 12. The first face 11 is the bottom face in FIG. 1A, and the second face 12 is the top face in FIG. 1A. The second face 12 is the exit face that emits light from the inside of the light-guiding member 1 to the outside. Therefore, the light-guiding member 1 receives light from one end face, which is the incident face 10, and the second face 12, which is the exit face, emits light.

In this embodiment, the second surface 12 is a plane parallel to the X-Y plane. The incident surface 10 is a plane parallel to the X-Z plane. The "X-Y plane" here refers to a plane that includes the X-axis and the Y-axis and is perpendicular to the Z-axis. Similarly, the "X-Z plane" here refers to a plane that includes the X-axis and the Z-axis and is perpendicular to the Y-axis. In other words, the second surface 12 is a plane perpendicular to the Z-axis, and the incident surface 10 is a plane perpendicular to the Y-axis. Therefore, the second surface 12 and the incident surface 10 are perpendicular to each other.

On the other hand, the first surface 11 is not parallel to the X-Y plane, but is a plane inclined relative to the X-Y plane. In other words, the first surface 11 and the incident surface 10 are not perpendicular to each other. Specifically, the first surface 11 is inclined relative to the X-Y plane so that the first surface 11 approaches the second surface 12 as it moves away from the incident surface 10. In other words, in this embodiment, the first surface 11 and the second surface 12 are inclined relative to each other.

In this embodiment, the light distribution control unit 14 is provided on the second surface 12. The light distribution control unit 14 includes a lens. In this embodiment, as an example, it includes a cylindrical lens. The light distribution control unit 14 will be described in detail in the section "(2.7) Light Distribution Control Unit."

The light control body 2 is disposed between the light source 4 and the incident surface 10 of the light guide member 1. The light control body 2 controls the light output from the light source 4 and incident on the incident surface 10. In this embodiment, the light control body 2 has a collimating function that makes the light output from the light source 4 closer to parallel light. That is, the light control body 2 is a collimating lens that, when light that spreads radially from the light source 4 is incident, focuses this light toward the incident surface 10, making it closer to parallel light. Here, the light emitted from the light source 4 is incident on the incident surface 10 of the light guide member 1 through the light control body 2. Therefore, the light from the light source 4 is controlled by the light control body 2 having the collimating function to narrow the spread angle, and is emitted toward the incident surface 10 of the light guide member 1. In this embodiment, it is assumed that the light from the light source 4, which is an ideal point light source, is controlled by the light control body 2 to be ideal parallel light.

Details will be explained in the section "(2.4) Oblique Light Entry", but in this embodiment, as shown in FIG. 1A, the optical axis Ax1 of the light incident from the incident surface 10 of the light-guiding member 1 is inclined with respect to the first surface 11 so that the distance to the first surface 11 decreases with increasing distance from the incident surface 10. Therefore, the parallel light emitted from the light control body 2 to the incident surface 10 of the light-guiding member 1 becomes parallel light inclined with respect to the first surface 11 so that the distance to the first surface 11 decreases with increasing distance from the incident surface 10. Also, the dotted arrows in the drawings conceptually represent light rays (or optical paths) and do not have any substance.

In this embodiment, as shown in FIG. 3, the multiple light control bodies 2 are formed to be aligned in the X-axis direction at the end constituting the incident surface 10 of the light guide member 1. That is, in this embodiment, the light control bodies 2 are integral with the light guide member 1. As already described, the multiple light control bodies 2 correspond one-to-one to the multiple light sources 4. Therefore, the multiple light control bodies 2 each control the spread angle of the light emitted by the corresponding light source 4, and emit the light to the incident surface 10. The shape of the light control body 2 will be described in detail in the sections "(2.5) Shape conversion function" and "(2.6) Asymmetric shape".

The prism 3 is provided on the first surface 11 and reflects light passing through the inside of the light-guiding member 1 toward the second surface 12. In this embodiment, a plurality of prisms 3 are provided on the first surface 11. The prisms 3 are configured to totally reflect the incident light. Of course, the prisms 3 are not limited to totally reflecting all the incident light, and may also include a configuration in which some light passes through the inside of the prism 3 without being totally reflected.

In the light guide member 1, most of the light incident from the incident surface 10 is not reflected at any part of the first surface 11 or the second surface 12 except the prism 3, but is reflected by the prism 3 and is emitted from the second surface 12. In other words, the light guide member 1 includes a direct optical path L1 that causes the light incident from the incident surface 10 to be directly reflected by the prism 3 and emitted from the second surface 12.

In this embodiment, the prism 3 is formed on the first surface 11 so that its cross section viewed from one side in the X-axis direction forms a triangular recess. The prism 3 is formed, for example, by processing the first surface 11 of the light-guiding member 1. As shown in FIG. 1B, the prism 3 has a reflecting surface 30 that reflects light incident through the inside of the light-guiding member 1 toward the second surface 12. FIG. 1B is a schematic end view in which the area A1 in FIG. 1A is enlarged.

The angle θ1 between the reflecting surface 30 and the first surface 11 (i.e., the inclination angle of the reflecting surface 30) is an angle such that the incident angle θ0 of the light incident on the reflecting surface 30 is equal to or greater than the critical angle. In other words, the reflecting surface 30 is inclined with respect to the first surface 11 so that the incident light is totally reflected. In addition, the inclination angle θ1 of the reflecting surface 30 is set so that the light totally reflected by the reflecting surface 30 is incident on the second surface 12 in a direction perpendicular to the second surface 12.

In this embodiment, as shown in Figures 7A and 7B, the multiple prisms 3 are arranged in a zigzag pattern on the first surface 11 when viewed from one side in the Z-axis direction. Here, Figure 7A is a schematic plan view in which area A1 in Figure 6C is enlarged. Figure 7B is a drawing that shows a schematic end face of line B1-B1 in Figure 7A. Although Figure 7A shows only a portion of the first surface 11, in reality, the multiple prisms 3 are formed over substantially the entire area of the first surface 11.

Specifically, each prism 3 has a length in the X-axis direction, and the prisms 3 are arranged at intervals in the longitudinal direction (X-axis direction). Furthermore, the prisms 3 are also arranged at intervals in the Y-axis direction. If the rows of prisms arranged in the X-axis direction are the first, second, third, etc., counting from the entrance surface 10 side in the Y-axis direction, the prisms 3 included in the even-numbered rows and the prisms 3 included in the odd-numbered rows are shifted from each other in the X-axis direction. Here, the prisms 3 included in the even-numbered rows and the prisms 3 included in the odd-numbered rows are arranged so that their ends in the longitudinal direction (X-axis direction) overlap in the Y-axis direction. With this arrangement, the prisms 3 are arranged without gaps in the X-axis direction as viewed from the entrance surface 10, and the light entering the light-guiding member 1 from the entrance surface 10 is reflected by one of the prisms 3.

In this embodiment, as an example, the multiple prisms 3 are all the same shape. Therefore, as shown in FIG. 7B, the inclination angle θ1 of the reflecting surface 30 is the same for the multiple prisms 3 arranged in the Y-axis direction. In addition, the size of the prisms 3, such as the longitudinal dimension of the prisms 3 and the depth of the recess as the prism 3 (in other words, the height of the prism 3), is also the same for the multiple prisms 3. That is, in this embodiment, the prisms 3 are arranged in a row in the direction in which light is incident on the incident surface 10 (Y-axis direction). Here, the multiple prisms 3 are the same shape. Therefore, if the incident angle θ0 of the light incident on the reflecting surface 30 is constant, the direction of the light reflected by the reflecting surface 30 of the prism 3 is the same regardless of which of the multiple prisms 3 the light is incident on. Therefore, it is possible to make all the light reflected by the multiple prisms 3 incident in a direction perpendicular to the second surface 12.

Furthermore, as an example, the depth of the recess as the prism 3 (in other words, the height of the prism 3) is 1 μm or more and 100 μm or less. Similarly, as an example, the pitch in the Y-axis direction of the multiple prisms 3 is 1 μm or more and 1000 μm or less. As a specific example, the depth of the recess as the prism 3 is several tens of μm, and the pitch in the Y-axis direction of the multiple prisms 3 is several hundred μm.

The light emission principle of the optical system 100 of this embodiment will be explained below with reference to Figures 1A and 1B.

First, as shown in FIG. 1A, the light emitted from the light source 4 passes through the corresponding light control body 2, whereby the spread angle is controlled. Then, the light with the controlled spread angle is emitted from the light control body 2 toward the incident surface 10 of the light-guiding member 1. In this embodiment, the light emitted from the light control body 2 becomes parallel light parallel to the second surface 12, and is incident perpendicularly to the incident surface 10.

As already mentioned, the optical axis Ax1 of the light incident from the incident surface 10 of the light-guiding member 1 is inclined with respect to the first surface 11 so that the distance to the first surface 11 decreases the farther away from the incident surface 10. Therefore, most of the light incident on the incident surface 10 reaches the first surface 11 without reaching the second surface 12 or the end surface 13 opposite the incident surface 10 of the light-guiding member 1.

As shown in FIG. 1B, most of the light incident on the incident surface 10 is totally reflected by the reflecting surface 30 of one of the multiple prisms 3 provided on the first surface 11, without being reflected by the first surface 11 and the second surface 12. In other words, the light guide member 1 includes a direct optical path L1 that causes the light incident on the incident surface 10 to be directly reflected by the prism 3 and emitted from the second surface 12. Furthermore, in this embodiment, the direct optical path L1 includes an optical path of light totally reflected by the prism 3. The light totally reflected by the reflecting surface 30 of the prism 3 follows an optical path perpendicular to the second surface 12 and is emitted from the second surface 12.

Here, in this embodiment, as described above, the inclination angle θ1 of the reflecting surface 30 is the same in the multiple prisms 3. By the parallel light parallel to the second surface 12 being incident on such multiple prisms 3, the incident angle θ0 of the light incident on the reflecting surface 30 is also constant. Therefore, the direction of the light reflected by the reflecting surface 30 is the same in any of the multiple prisms 3. Therefore, in this embodiment, all the light that reaches the second surface 12 on the direct optical path L1 is incident on the second surface 12 at the same angle. Here, the "same angle" may include not only the strictly same angle, but also an error of up to about 2 degrees or 3 degrees. Ideally, all the light that reaches the second surface 12 on the direct optical path L1 is incident at 90 degrees, that is, perpendicular to the second surface 12.

In this embodiment, multiple prisms 3 are arranged across the entire area of the second surface 12, so that the light that passes through the direct optical path L1 as described above is emitted evenly from the entire area of the second surface 12 of the light-guiding member 1. This results in the entire second surface 12 emitting light.

The advantages of the optical system 100 of this embodiment are explained below, along with a comparison with a typical light-guiding member (light-guiding plate).

In a typical light-guiding member, light incident on the entrance surface of the light-guiding member is guided inside the light-guiding member while being repeatedly reflected multiple times on both surfaces in the thickness direction of the light-guiding member (corresponding to first surface 11 and second surface 12). Then, a prism provided on one surface in the thickness direction of the light-guiding member (corresponding to first surface 11) breaks the condition of total reflection (i.e., incident angle ≧ critical angle), and light is emitted from the other surface in the thickness direction of the light-guiding member (corresponding to second surface 12) which serves as the exit surface. As a result, even in a typical light-guiding member, the entire exit surface emits light.

However, in a typical light-guiding member as described above, the light incident from the incident surface of the light-guiding member is guided to a part of the light-guiding member away from the incident surface by repeatedly reflecting multiple times on both sides of the light-guiding member in the thickness direction. Therefore, the more times the light is totally reflected, the more likely it is that the condition for total reflection (i.e., incident angle ≧ critical angle) will be violated, and the more likely it is that light will leak from one surface of the light-guiding member in the thickness direction (corresponding to first surface 11).

In particular, when an optical system including a light-guiding member is applied to a head-up display mounted on a moving body B1, such as the display system 300 according to this embodiment, a relatively narrow viewing angle and high light intensity are required for the light-guiding member. That is, in a head-up display, it is preferable for the light distribution to be controlled from the light-guiding member in accordance with the optical system 320, so a narrower viewing angle is required compared to light-guiding members for the backlight of a typical liquid crystal display. Since it is difficult to narrow the viewing angle with a typical light-guiding member, when a typical light-guiding member is used in a head-up display, light is likely to be emitted in unnecessary directions.

On the other hand, in the optical system 100 according to the present embodiment, since the optical control body 2 and the prism 3 are provided as described above, most of the light incident on the incident surface 10 of the light-guiding member 1 follows the direct optical path L1. In other words, in this embodiment, most of the light incident on the incident surface 10 of the light-guiding member 1 does not repeat total reflection at the first surface 11 and the second surface 12, but directly enters the prism 3 and exits from the second surface 12. For this reason, in this embodiment, unlike a general light-guiding member, the conditions for total reflection are not broken, so light is less likely to leak from the first surface 11, and as a result, the light extraction efficiency can be improved. In addition, since most of the light incident on the incident surface 10 is parallel light, the light is less likely to spread, and the light reflected by the prism 3 and exiting from the second surface 12 can maintain a relatively narrow exit angle. In the optical system 100 according to the present embodiment, a relatively large light intensity can be achieved by using the direct optical path L1 while exiting most of the light incident on the incident surface 10 at such a narrow angle.

In this embodiment, the light emitted from the second surface 12 via the direct optical path L1 is 50% or more of the light incident on the light-guiding member 1 from the incident surface 10. That is, although some of the light incident on the incident surface 10 of the light-guiding member 1 may not pass through the direct optical path L1, in this embodiment, the majority (more than half) of the light incident on the incident surface 10 is emitted from the second surface 12 via the direct optical path L1. As a result, the light extraction efficiency of the light-guiding member 1 is at least 50%. It is more preferable that the light extraction efficiency of the light-guiding member 1 is 70% or more, and may further be 80% or more.

In this way, the light extraction efficiency of the light guide member 1 is improved, and optical elements such as a reflective sheet, a prism sheet, a reflective polarizing film (DBEF: Dual Brightness Enhancement Film), and a Fresnel lens sheet are not required on the first surface 11 side of the light guide member 1. In other words, since light is less likely to leak from the first surface 11, sufficient light extraction efficiency can be achieved without placing these optical elements on the first surface 11 side of the light guide member 1.

(2.4) Oblique Light Entry Next, a configuration regarding light entry (light incidence) from the incidence surface 10 of the light-guiding member 1 will be described in detail with reference to FIGS. 1A and 1B. FIG.

In other words, in the optical system 100 according to this embodiment, as shown in FIG. 1A, the optical axis Ax1 of the light incident from the incident surface 10 is inclined with respect to the first surface 11 so that the distance to the first surface 11 decreases with increasing distance from the incident surface 10. In particular, in this embodiment, parallel light is incident from the light control body 2 on the incident surface 10 of the light-guiding member 1, and all of the light rays contained in this parallel light are inclined with respect to the first surface 11. Moreover, in this embodiment, the first surface 11 is a flat surface, and the light rays contained in the parallel light incident on the incident surface 10 of the light-guiding member 1 are inclined at the same angle with respect to the first surface 11.

Specifically, the first surface 11 and the second surface 12 are not parallel and are inclined to each other. That is, as described above, the second surface 12 is a plane parallel to the X-Y plane, whereas the first surface 11 is not parallel to the X-Y plane and is inclined to the X-Y plane. Here, the first surface 11 is inclined to the X-Y plane so as to approach the second surface 12 as it moves away from the incident surface 10. In short, the thickness of the light-guiding member 1 is not constant, but changes so as to become gradually thinner in a certain direction, because the first surface 11 and the second surface 12, which are both surfaces in the thickness direction, are inclined to each other. In this embodiment, the first surface 11 is inclined to the second surface 12 in the Y-axis direction so as to approach the second surface 12 as it moves away from the incident surface 10. Therefore, the thickness of the light-guiding member 1 is largest at the end on the incident surface 10 side, and gradually decreases in the Y-axis direction as it moves away from the incident surface 10, that is, as it moves closer to the end surface 13.

On the other hand, the light incident from the incident surface 10 is controlled by the light control body 2 to be parallel light parallel to the second surface 12. In other words, the optical axis Ax1 of the light incident from the incident surface 10 is parallel to the second surface 12. Therefore, the optical axis Ax1 of the light incident from the incident surface 10 is inclined at a predetermined inclination angle with respect to the first surface 11, and this inclination angle is the same as the inclination angle of the first surface 11 with respect to the X-Y plane (second surface 12).

More specifically, as shown in FIG. 1A, the light control body 2 has a path generating section 23 that forms light paths L31, L32, and L33 between the light source 4 and the incident surface 10. When viewed from the incident surface 10, the path generating section 23 extends along a straight line (here, optical axis Ax1) that is inclined with respect to the first surface 11, and forms light paths L31, L32, and L33 between the light source 4 and the incident surface 10. In other words, in this embodiment, as described above, the light control body 2 is integral with the light-guiding member 1.

In other words, the light control body 2 includes a portion (path generating section 23) that protrudes along the optical axis Ax1 inclined with respect to the first surface 11 when viewed from the incident surface 10 of the light guide member 1. The light control body 2 forms optical paths L31, L32, and L33 between the light source 4 and the incident surface 10 at this path generating section 23. Therefore, the light from the light source 4 enters the incident surface 10 along the optical axis Ax1 inclined with respect to the first surface 11 through the path generating section 23 of the light control body 2. In other words, the light from the light source 4 enters the incident surface 10 of the light guide member 1 through the inside of the light control body 2 (path generating section 23). In this way, the optical axis Ax1 of the light entering from the incident surface 10 is inclined at a predetermined inclination angle with respect to the first surface 11.

According to the above-mentioned configuration, the light incident on the light-guiding member 1 from the incident surface 10 passes through the inside of the light-guiding member 1 and is obliquely incident on the first surface 11. In other words, the light incident on the light-guiding member 1 from the incident surface 10 is actively incident on the first surface 11. At this time, by the light being incident on the multiple prisms 3 formed on the first surface 11, the light is reflected by the reflecting surface 30 of the prisms 3 toward the second surface 12 as shown in FIG. 1B. As a result, the light incident on the light-guiding member 1 from the incident surface 10 passes through the direct optical path L1 and is emitted from the second surface 12.

In this way, the light incident from the incident surface 10 approaches the first surface 11 as it moves away from the incident surface 10, that is, as it travels inside the light-guiding member 1, and is more likely to be incident on the first surface 11 (including the prism 3). Therefore, most of the light incident from the incident surface 10 is more likely to be incident on the first surface 11 before reaching the end surface 13 of the light-guiding member 1 that faces the incident surface 10. In particular, by actively directing the light toward the first surface 11, most of the light incident from the incident surface 10 can be emitted from the second surface 12 in the direct optical path L1 while reducing the dimension of the light-guiding member 1 in the Y-axis direction. In other words, it is possible to efficiently emit light from the second surface 12 while suppressing light leakage from the end surface 13. As a result, it is easy to increase the proportion of light emitted from the second surface 12 to the outside of the light-guiding member 1 from the incident surface 10 through the direct optical path L1, and the light extraction efficiency can be improved.

In addition, in this embodiment, as shown in FIG. 1A, the end face 13 is bisected in the Z-axis direction into an inclined surface 131 and a vertical surface 132. In other words, the end face 13 includes the inclined surface 131 and the vertical surface 132. The inclined surface 131 is a plane that is inclined with respect to the incident surface 10 so that the distance from the incident surface 10 in the Y-axis direction is greater on the second surface 12 side than on the first surface 11 side. On the other hand, the vertical surface 132 is a plane that is parallel to the incident surface 10. Here, the inclined surface 131 is adjacent to the second surface 12, and the vertical surface 132 is adjacent to the first surface 11.

By having such an inclined surface 131 on the end face 13, even if a portion of the light incident from the incident surface 10 reaches the end face 13 without being incident on the first surface 11, it is possible for this light to be emitted from the second surface 12. That is, when a portion of the light incident from the incident surface 10 is incident on the inclined surface 131 of the end face 13, this light is totally reflected by the inclined surface 131 toward the second surface 12 and is emitted from the second surface 12. As a result, in addition to the light emitted from the second surface 12 to the outside of the light-guiding member 1 through the direct optical path L1, even the light that reaches the end face 13 can be effectively extracted from the second surface 12, and the light extraction efficiency can be further improved.

(2.5) Shape Transformation Function Next, the shape transformation function of the light control unit 2 will be described in detail with reference to FIG. 2 and FIGS. 8A to 11B.

In other words, in the optical system 100 according to this embodiment, as shown in FIG. 2, the light control unit 2 has a shape conversion function that converts the shape projected on the projection surface S1 parallel to the incident surface 10 from the first shape F1 of the light output from the light source 4 to the second shape F2 of the light incident on the incident surface 10. In FIG. 2, the shape (first shape F1) of the light output from the light source 4 projected on the projection surface S1 and the shape (second shape F2) of the light incident on the incident surface 10 projected on the projection surface S1 are each shown in a bubble. Thus, in this embodiment, the light control unit 2 has a shape conversion function that converts the projection shape of the light on the projection surface S1 (here, the incident surface 10) in addition to the collimation function that brings the light output from the light source 4 closer to parallel light.

According to the shape conversion function, the light output from the light source 4 is projected onto the projection surface S1 in a shape converted from the first shape F1 to the second shape F2, and is incident on the entrance surface 10. The second shape F2 is a shape converted by the shape conversion function based on the first shape F1, and is a shape different from the first shape F1. As an example, in this embodiment, as shown in FIG. 2, the first shape F1 is a shape based on a circle, while the second shape F2 is a shape based on a rectangle.

More specifically, the second shape F2 is a shape in which the first shape F1, which is based on a circle, is deformed to become closer to a rectangle by protruding at least one corner F21. In other words, the second shape F2 is a shape in which the first shape F1 is expanded as if stretched in all four directions. With this shape transformation function, the first shape F1 is approximated by the inscribed circle of the second shape F2. Therefore, the circumscribed circle of the second shape F2 is larger than the circumscribed circle of the first shape F1.

In other words, the second shape F2 is a shape in which at least one corner F21 is added to the first shape F1 so as to make the first shape F1 closer to a polygonal shape. With this shape conversion function, light is incident on the incident surface 10 such that its projection (illumination) area becomes the second shape F2, which is less rounded than the first shape F1. Thus, by allowing light to be incident on the vicinity of the corners of the incident surface 10, more uniform light is incident on the entire area of the incident surface 10.

In this embodiment, as described above, a plurality of light sources 4 and a plurality of light control bodies 2 are provided. Therefore, the plurality of light control bodies 2 convert the shape of the light incident on the incident surface 10 by the shape conversion function for the light incident from the corresponding light sources 4, so that more uniform light is incident on the entire area of the incident surface 10. For example, when light of the first shape F1 based on a circular shape is incident on the incident surface 10, gaps or overlapping areas are likely to occur between the light incident on the incident surface 10 from two adjacent light sources 4. In contrast, when light of the second shape F2 based on a rectangular shape is incident on the incident surface 10, gaps or overlapping areas are unlikely to occur between the light incident on the incident surface 10 from two adjacent light sources 4.

The shape transformation function described above can be realized, for example, by the configuration of the light control body 2 described below.

That is, in this embodiment, as shown in Figures 8A to 8C, the light control body 2 (optical member 20) has an entrance lens 21. Figure 8B is a cross-sectional view taken along line B1-B1 in Figure 8A. Figure 8C is a cross-sectional view taken along line C1-C1 in Figure 8A.

The incident lens 21 has a main incident surface 211 and a secondary incident surface 212. The main incident surface 211 is disposed so as to face the light source 4. The secondary incident surface 212 is oriented toward a normal line L21 of the main incident surface 211. The secondary incident surface 212 is located at least partially around the main incident surface 211. The secondary incident surface 212 may be parallel (i.e., not inclined) or inclined with respect to the normal line L21 of the main incident surface 211.

Here, the entrance lens 21 takes in the light output from the light source 4 from the main entrance surface 211 and the secondary entrance surface 212. Therefore, when passing through the entrance lens 21, at least a portion of the light from the light source 4 is refracted at the main entrance surface 211 or the secondary entrance surface 212 depending on the angle of incidence of the light ray to the main entrance surface 211 or the secondary entrance surface 212. In this way, the light control body 2 refracts at least a portion of the light incident on the main entrance surface 211 or the secondary entrance surface 212, and emits it toward the entrance surface 10 of the light-guiding member 1.

The light control body 2 further includes an outer peripheral surface 213. When viewed from the auxiliary incident surface 212, the outer peripheral surface 213 is located on the opposite side of the normal line L21 of the main incident surface 211. The outer peripheral surface 213 totally reflects the light incident from the auxiliary incident surface 212 into the light control body 2 toward the incident surface 10 of the light-guiding member 1. In other words, at least a portion of the light incident from the auxiliary incident surface 212 into the light control body 2 is totally reflected by the outer peripheral surface 213 and emitted toward the incident surface 10 of the light-guiding member 1.

The light control body 2 has a plurality of lens surfaces 201 to 205 on the surface facing the light source 4. The "facing surface" here means the facing surface, that is, the surface of the light control body 2 facing the light source 4 is the surface of the light control body 2 that faces the light source 4. In this embodiment, as an example, the surface of the light control body 2 facing the light source 4 is made of the entrance lens 21 of the light control body 2. As described above, the entrance lens 21 has a main entrance surface 211 and a secondary entrance surface 212, and in this embodiment, as an example, the secondary entrance surface 212 is divided into a plurality of lens surfaces 201 to 205. The secondary entrance surface 212 is divided into a plurality of (here, five) lens surfaces 201 to 205 in the circumferential direction centered on the axis facing the light source 4 in the light control body 2. The "facing axis" here means a virtual axis extending in the facing direction. In other words, the axis of the light control body 2 facing the light source 4 is a virtual axis extending from the light control body 2 along the direction in which the light control body 2 and the light source 4 face each other. In this embodiment, as an example, the axis of the light control body 2 facing the light source 4 is the normal L21 of the main incidence surface 211 (see FIG. 2).

The inclination angle of the surface of the light control body 2 facing the light source 4 with respect to the axis of the light source 4 varies in the circumferential direction centered on the axis of the light source 4. Specifically, the surface of the light control body 2 facing the light source 4 (here, the entrance lens 21) includes a plurality of lens surfaces 201 to 205 as described above. The inclination angles of the lens surfaces 201 to 205 with respect to the axis of the light source 4 (here, the normal line L21) are not constant in the circumferential direction centered on the axis of the light source 4. Specifically, the inclination angle of the lens surfaces 202 and 204 with respect to the axis of the light source 4 is larger than the inclination angle of the lens surfaces 201, 203, and 205 with respect to the axis of the light source 4. In other words, the lens surfaces 202 and 204 are configured to have a larger inclination with respect to the normal line L21 compared to the lens surfaces 201, 203, and 205.

The surface of the light control body 2 facing the light source 4 has an asymmetric shape in one direction perpendicular to the axis of opposition to the light source 4 (here, normal line L21). In this embodiment, the entrance lens 21, which is the surface of the light control body 2 facing the light source 4, has an asymmetric shape in the Z-axis direction. Specifically, the entrance lens 21 has a secondary entrance surface 212 (lens surfaces 202, 203, 204) only on one side in the Z-axis direction when viewed from the primary entrance surface 211, and the other side in the Z-axis direction is open.

With the configuration described above, the light control body 2 can achieve a shape conversion function, and the range within the light-guiding member 1 that the light incident on the incident surface 10 reaches can be controlled regardless of the first shape F1, which is the shape of the light output from the light source 4.

FIGS. 9A to 11B are diagrams showing the results of a comparison between the optical control unit 2 of the optical system 100 according to this embodiment and an optical control unit 2X according to a comparative example. The optical control unit 2X according to the comparative example has a secondary incidence surface 212 that is not divided into a plurality of lens surfaces 201 to 205, but is composed of a single continuous curved surface.

9A to 11B, the range where the light from the light source 4 reaches is shown by a shaded area (dots). The shaded area is set in three stages according to the intensity of the light from the light source 4, and the area with the higher light intensity is shaded darker. FIG. 11A shows the light intensity distribution (strictly speaking, illuminance distribution) on the first surface 11 when the light guide member 1 is viewed from the first surface 11 side in the thickness direction (Z axis direction) when light is emitted from the light control body 2 according to this embodiment to the light guide member 1. FIG. 11B shows the light intensity distribution (strictly speaking, illuminance distribution) on the first surface 11 when the light guide member 1 is viewed from the first surface 11 side in the thickness direction (Z axis direction) when light is emitted from the light control body 2X according to the comparative example to the light guide member 1. Both FIG. 11A and FIG. 11B show the intensity distribution (illuminance distribution) of light incident on the light guide member 1 from one light control body 2, 2X.

9A and 10A, in the light control body 2 according to this embodiment, the light output from the light source 4 enters the light control body 2 from the entrance lens 21 and spreads over a relatively wide range inside the light control body 2. In particular, according to the shape conversion function of the light control body 2, the projection shape on the projection surface S1 (entrance surface 10) is converted from a first shape F1 (see FIG. 2) based on a circle to a second shape F2 (see FIG. 2) based on a rectangle. Specifically, the light incident on the lens surfaces 202 and 204 reaches a position farther away from the normal line L21 when viewed from one of the extension directions of the normal line L21 of the main entrance surface 211 than the light incident on the lens surfaces 201, 203, and 205. That is, since lens surfaces 202 and 204 have a larger inclination angle with respect to the opposing axis (here, normal line L21) than lens surfaces 201, 203, and 205, the light rays incident on lens surfaces 202 and 204 are refracted so that the inclination angle with respect to normal line L21 is larger. As a result, the light incident on lens surfaces 202 and 204 of secondary incident surface 212 makes it easier for the light to reach the corners of light control body 2.

In contrast, in the light control body 2X according to the comparative example, as shown in FIG. 9B and FIG. 10B, the light output from the light source 4 enters the light control body 2X from the entrance lens 21 and remains within a relatively narrow range inside the light control body 2X. Specifically, the light that enters the secondary entrance surface 212 spreads uniformly when viewed from one side in the extension direction of the normal L21 of the primary entrance surface 211, and reaches only within a certain range from the normal L21. As a result, light does not easily reach the corners of the light control body 2X, and compared to the light control body 2 according to this embodiment, the range that the light reaches is narrower when viewed from one side in the extension direction of the normal L21 of the primary entrance surface 211.

Therefore, according to the light control body 2 of this embodiment, as shown in FIG. 11A, the light incident from the incident surface 10 spreads over a relatively wide range even inside the light guide member 1. On the other hand, according to the light control body 2X of the comparative example, as shown in FIG. 11B, the range where the light incident from the incident surface 10 reaches is limited to a relatively narrow range even inside the light guide member 1. More specifically, according to the light control body 2 of this embodiment, as shown in FIG. 11A, when the light guide member 1 is viewed from one side in the thickness direction (Z axis direction), the light reaches a substantially rectangular area. In contrast, according to the light control body 2X of the comparative example, as shown in FIG. 11B, when the light guide member 1 is viewed from one side in the thickness direction (Z axis direction), the light reaches a substantially elliptical area. Therefore, when light is incident on the light guide member 1 from multiple light control bodies 2, in this embodiment, the light is more likely to reach the entire area of the first surface 11 than in the comparative example, and the light is more likely to be extracted uniformly from the entire area of the second surface 12.

(2.6) Asymmetric Shape Next, the asymmetric shape of the light control unit 2 will be described in detail with reference to FIG. 2 and FIGS. 12A to 12C.

That is, the optical element 20 used as the light control body 2 in the optical system 100 according to this embodiment includes an input lens 21 and an output section 22, as shown in FIG. 2. The optical element 20 outputs light incident on the input lens 21 from the light source 4 from the output section 22. The input lens 21 has a main input surface 211 and a secondary input surface 212. The main input surface 211 is disposed so as to face the light source 4. The secondary input surface 212 is oriented toward the normal line L21 of the main input surface 211. The secondary input surface 212 is located at least in a part of the periphery of the main input surface 211. The optical axis Ax2 of the light source 4 is inclined with respect to the normal line L21 of the main input surface 211.

In the example of FIG. 2, the optical axis Ax2 of the light source 4 is inclined by an inclination angle θ2 toward the first surface 11 with respect to the normal L21 of the main incidence surface 211 when viewed from one side in the X-axis direction. Here, the optical axis Ax2 of the light source 4 and the normal L21 of the main incidence surface 211 are both parallel to the Y-Z plane. The "Y-Z plane" here is a plane that includes the Y axis and the Z axis and is perpendicular to the X axis. In other words, the optical axis Ax2 of the light source 4 and the normal L21 of the main incidence surface 211 are both perpendicular to the X axis.

More specifically, the optical axis Ax2 of the light source 4 and the normal L21 of the main incidence surface 211 intersect on the surface (light-emitting surface) of the light source 4. In other words, the light source 4 is positioned so that the center point of its light-emitting surface is located on the normal L21 of the main incidence surface 211. The light source 4 is then held in a position tilted by an inclination angle θ2 toward the first surface 11. As a result, the light from the light source 4 is incident on the entrance lens 21 of the optical member 20 in an asymmetric manner with respect to the normal L21 of the main incidence surface 211.

The light source 4 has directionality, and the intensity of the light output from the light source 4 changes depending on the direction viewed from the light source 4. For example, if the maximum intensity of the light beam emitted from the light source 4 is "100%" and the intensity of each light beam from the light source 4 is expressed as a percentage of the maximum intensity, the light emitted from the light source 4 contains light beams of various intensities, such as 10%, 20%, or 30%. In the following, it is assumed that the intensity of the light beam on the optical axis Ax2 of the light source 4 is maximum, that is, 100%, and that the intensity of the light beam decreases as the angle with respect to the optical axis Ax2 increases.

As shown in FIG. 12A, the light beam incident on the entrance lens 21 from the light source 4 includes a main ray L11, a first auxiliary ray L12, and a second auxiliary ray L13. The first auxiliary ray L12 and the second auxiliary ray L13 are all smaller in intensity than the main ray L11. Here, the main ray L11, the first auxiliary ray L12, and the second auxiliary ray L13 are arranged in the order of the main ray L11, the first auxiliary ray L12, and the second auxiliary ray L13 in a direction perpendicular to the normal line L21 of the main entrance surface 211. The first auxiliary ray L12 and the second auxiliary ray L13 only need to have an intensity smaller than that of the main ray L11. For example, if the intensity of the main ray L11 is 90%, the intensity of the first auxiliary ray L12 and the second auxiliary ray L13 is less than 90%. The intensities of the first auxiliary light beam L12 and the second auxiliary light beam L13 may be the same or different from each other.

Specifically, these light rays are arranged in the Z-axis direction perpendicular to the normal line L21 of the main incidence surface 211, in the order of main light ray L11, first auxiliary light ray L12, and second auxiliary light ray L13, from the first surface 11 side (lower side in FIG. 12A). In other words, main light ray L11, first auxiliary light ray L12, and second auxiliary light ray L13 are arranged from the first surface 11 side in order of decreasing intensity.

Here, in this embodiment, the intensity of the main light ray L11 is the maximum intensity among the light rays incident on the entrance lens 21 from the light source 4. In other words, the intensity of the main light ray L11 is 100%. In contrast, the intensities of the first auxiliary light ray L12 and the second auxiliary light ray L13 are both less than 100%. As an example, in this embodiment, it is assumed that the intensities of the first auxiliary light ray L12 and the second auxiliary light ray L13 are both 70%. In other words, the intensities of the first auxiliary light ray L12 and the second auxiliary light ray L13 are the same.

On the other hand, as shown in FIG. 12A, the light beams emitted from the light source 4 include a third auxiliary light beam L14 and a fourth auxiliary light beam L15 in addition to the main light beam L11, the first auxiliary light beam L12, and the second auxiliary light beam L13. The third auxiliary light beam L14 and the fourth auxiliary light beam L15 have lower intensities than the first auxiliary light beam L12 and the second auxiliary light beam L13, respectively. The intensities of the third auxiliary light beam L14 and the fourth auxiliary light beam L15 may be the same or different from each other. As an example, in this embodiment, it is assumed that the intensities of the third auxiliary light beam L14 and the fourth auxiliary light beam L15 are both 10%. In other words, the intensities of the third auxiliary light beam L14 and the fourth auxiliary light beam L15 are the same.

In the example of FIG. 12A, neither the third auxiliary light ray L14 nor the fourth auxiliary light ray L15 enters the optical member 20. In other words, the third auxiliary light ray L14 nor the fourth auxiliary light ray L15 reach the incident surface 10 of the light-guiding member 1. However, since the third auxiliary light ray L14 and the fourth auxiliary light ray L15 have sufficiently low intensity compared to the principal light ray L11, the first auxiliary light ray L12, and the second auxiliary light ray L13, the loss due to not reaching the incident surface 10 is small.

Furthermore, in this embodiment, the chief ray L11 is incident on the auxiliary incident surface 212. That is, of the main incident surface 211 and the auxiliary incident surface 212 in the incident lens 21, the chief ray L11 is incident on the auxiliary incident surface 212. As shown in FIG. 12A, the chief ray L11 incident on the auxiliary incident surface 212 is refracted at the auxiliary incident surface 212 and is totally reflected by the outer peripheral surface 213 toward the incident surface 10. As a result, the chief ray L11 is emitted from the exit portion 22 toward the incident surface 10.

The secondary incidence surface 212 also has an asymmetric shape with respect to the normal line L21 of the primary incidence surface 211. In this embodiment, the incidence lens 21 has an asymmetric shape in the Z-axis direction. Specifically, the incidence lens 21 has the secondary incidence surface 212 (lens surfaces 202, 203, 204) only on one side in the Z-axis direction when viewed from the primary incidence surface 211, and the other side in the Z-axis direction is open.

In other words, light rays with relatively high intensity, including the principal ray L11, the first auxiliary ray L12, and the second auxiliary ray L13, are concentrated on the first surface 11 side (lower in FIG. 12A) of the optical member 20 (light control body 2) when viewed from the normal line L21 of the main incident surface 211. Therefore, the optical member 20 (light control body 2) consolidates the incident lenses 21 only in the portion where the light rays with relatively high intensity are concentrated, and adopts an asymmetric shape that simplifies the opposite side (upper in FIG. 12A), making it easier to keep the dimension t1 in the Z-axis direction small.

On the other hand, FIG. 12B shows an optical system 100Y as a comparative example equipped with an optical element 20Y, and an illumination system 200Y equipped with the same. In the illumination system 200Y according to this comparative example, the optical element 20Y has a symmetric shape in the Z-axis direction with respect to the normal line L21 of the main incidence surface 211. Specifically, the optical element 20Y employs a configuration on the opposite side (upper side in FIG. 12A) that is symmetric to the configuration on the first surface 11 side (lower side in FIG. 12A) of the optical element 20 according to this embodiment, as viewed from the normal line L21 of the main incidence surface 211.

Furthermore, in the illumination system 200Y according to the comparative example, the optical axis Ax2 of the light source 4 is located on the normal line L21 of the main incidence surface 211. In other words, in the comparative example, the optical axis Ax2 of the light source 4 is parallel to the normal line L21 of the main incidence surface 211.

In this comparative example, as shown in FIG. 12B, the principal ray L11 is located on the optical axis Ax2 of the light source 4. In addition, in the Z-axis direction, the third auxiliary ray L14 and the fourth auxiliary ray L15 are located on both sides of the principal ray L11, and the first auxiliary ray L12 and the second auxiliary ray L13 are located on both sides of them. As a result, in the illumination system 200Y according to the comparative example, all of the relatively high intensity light rays including the principal ray L11, the first auxiliary ray L12, and the second auxiliary ray L13 are incident on the incident surface 10 of the light-guiding member 1. However, in the optical member 20Y according to the comparative example, a symmetric shape in the Z-axis direction is adopted, so the dimension t2 in the Z-axis direction is larger than the dimension t1 of the optical member 20 according to this embodiment.

On the other hand, FIG. 12C shows an optical system 100Z as a comparative example equipped with a different optical member 20Z, and an illumination system 200Z equipped with the same. In the illumination system 200Z according to this comparative example, the optical member 20Z is configured by removing both ends in the Z-axis direction of the optical member 20Y according to the above comparative example, thereby making it thinner. The dimension t3 in the Z-axis direction of this optical member 20Z is the same as the dimension t1 of the optical member 20 according to this embodiment.

Furthermore, in the illumination system 200Z according to the comparative example, the optical axis Ax2 of the light source 4 is located on the normal line L21 of the main incidence surface 211. In other words, in the comparative example, the optical axis Ax2 of the light source 4 is parallel to the normal line L21 of the main incidence surface 211.

In this comparative example, as shown in FIG. 12C, the principal ray L11 is located on the optical axis Ax2 of the light source 4. In addition, the third auxiliary ray L14 and the fourth auxiliary ray L15 are located on both sides of the principal ray L11 in the Z-axis direction. However, the first auxiliary ray L12 and the second auxiliary ray L13 leak out from the optical member 20Z and do not enter the incident surface 10 of the light-guiding member 1. As a result, in the illumination system 200Z according to the comparative example, light rays with relatively high intensity, including the first auxiliary ray L12 and the second auxiliary ray L13, do not enter the incident surface 10 of the light-guiding member 1, and the light extraction efficiency is significantly lower than that of the present embodiment.

As described above, the optical element 20 according to this embodiment can improve the light capture efficiency of the optical element 20 while being more compact than the comparative examples shown in Figures 12B and 12C.

(2.7) Light Distribution Control Unit Next, the light distribution control unit 14 will be described in detail with reference to FIG.

That is, in this embodiment, at least one of the first surface 11 and the second surface 12 has a light distribution control unit 14. The light distribution control unit 14 controls the distribution of light extracted from the second surface 12, which is the emission surface. In this embodiment, as an example, the light distribution control unit 14 is provided on the second surface 12. Furthermore, in this embodiment, the light distribution control unit 14 is integrated with the light guide member 1 as a one-piece molded product. That is, in this embodiment, the light guide member 1 and the light distribution control unit 14 are one-piece molded products and are inseparably integrated.

In short, in this embodiment, the light guide member 1 includes a direct optical path L1 that causes light that enters the light guide member 1 from the entrance surface 10 to exit from the second surface 12 inside the light guide member 1 after only one reflection at the prism 3. Therefore, the shapes of the first surface 11 and the second surface 12 do not contribute to the guiding of light inside the light guide member 1, and even if the light distribution control unit 14 is provided on the first surface 11 or the second surface 12, the light guide performance of the light guide member 1 is unlikely to deteriorate.

Specifically, in this embodiment, the light distribution control unit 14 includes a lens. In other words, the light distribution control unit 14 functions as a lens, an optical element that refracts light to diverge or converge it. This allows the light distribution control unit 14 to control the light distribution by refracting the light extracted from the second surface 12, which is the exit surface, to diverge or converge it.

More specifically, the light distribution control unit 14 includes a multi-lens consisting of a group of small lenses 141. In this embodiment, each of the small lenses 141 is formed in a semi-cylindrical shape. Such small lenses 141 are arranged side by side in the X-axis direction. Here, the small lenses 141 are formed without gaps over the entire area of the second surface 12. A multi-lens consisting of a group of small lenses 141 of such a shape constitutes a so-called cylindrical lens.

(3) Modifications The first embodiment is merely one of various embodiments of the present disclosure. Various modifications of the first embodiment are possible depending on the design, etc., as long as the object of the present disclosure can be achieved. The figures described in the first embodiment are schematic diagrams, and the size and thickness ratios of the components in the figures do not necessarily reflect the actual dimensional ratios.

Below, we will list some variations of the first embodiment. The variations described below can be applied in appropriate combination with the first embodiment.

(3.1) First Modification As shown in FIGS. 13A to 13C, an optical system 100A according to a first modification differs from the optical system 100 according to embodiment 1 in the inclination angle θ3 of the reflecting surface 30 of the prism 3A with respect to the first surface 11.

That is, as shown in FIG. 13B, the inclination angle θ3 of the reflecting surface 30 of the prism 3A with respect to the first surface 11 is smaller than the maximum angle when the light incident from the incident surface 10 is totally reflected toward the second surface 12 along the direct optical path L1. In other words, the inclination angle θ3 of the reflecting surface 30 of the prism 3A in this modified example is smaller than the inclination angle θ1 (see FIG. 1B) of the reflecting surface 30 of the prism 3 in the first embodiment. As a result, even if the incident angle θ4 of the light incident on the reflecting surface 30 varies slightly, the incident angle θ4 is less likely to fall below the critical angle. In other words, even if the incident angle θ4 of the light incident on the reflecting surface 30 varies slightly, the light incident on the reflecting surface 30 is more likely to be totally reflected by the reflecting surface 30. As a result, the light leaking from the light guide member 1 through the reflecting surface 30 can be reduced, leading to improved light extraction efficiency.

However, in this modified example, the light ray incident on the second surface 12 via the direct optical path L1 follows an optical path that is inclined with respect to the Z axis. As a result, as shown in FIG. 13A, the light emitted from the second surface 12 is not emitted in a direction perpendicular to the second surface 12 (Z axis direction), but is emitted obliquely with respect to the normal to the second surface 12.

Therefore, as shown in FIG. 13C, the normal line L22 of the second surface 12A may be inclined with respect to the optical axis of the light incident on the second surface 12A on the direct optical path L1. In the example of FIG. 13C, the second surface 12A is not parallel to the XY plane, but is a plane inclined at an angle θ5 with respect to the XY plane. Here, the second surface 12A is inclined with respect to the XY plane so as to approach the first surface 11 as it moves away from the incident surface 10. As a result, the normal line L22 of the second surface 12A is inclined with respect to the optical axis of the light incident on the second surface 12A on the direct optical path L1. Therefore, the light incident on the second surface 12A on the direct optical path L1 is refracted at the second surface 12A and is emitted in a direction perpendicular to the XY plane. In other words, the light incident on the second surface 12A at an incident angle θ6 is emitted from the second surface 12A at an emission angle θ7 (>θ6).

(3.2) Second Modification The optical system 100B according to the second modification differs from the optical system 100 according to embodiment 1 in that the entire light control body 2B is inclined with respect to the light-guiding member 1, as shown in Figures 14A and 14B.

That is, to realize the configuration described in the section "(2.4) Oblique Light Entry", it is sufficient that the optical axis Ax1 of the light incident from the incident surface 10 of the light guide member 1 is inclined with respect to the first surface 11 so that the distance to the first surface 11 decreases the farther from the incident surface 10. According to this modified example, both surfaces in the thickness direction (Z-axis direction) of the light control body 2B are inclined with respect to the light guide member 1, so that the entire light control body 2B is inclined with respect to the light guide member 1. Even with this configuration, it is easy to increase the proportion of light emitted from the second surface 12 to the outside of the light guide member 1 through the direct optical path L1 to the light incident from the incident surface 10, and the light extraction efficiency can be improved.

In particular, in this modified example, as shown in FIG. 14B, the optical axis Ax1 of the light incident from the incident surface 10 of the light-guiding member 1 is inclined not only with respect to the first surface 11 but also with respect to the second surface 12. Here, the optical axis Ax1 is inclined with respect to the second surface 12 such that the distance to the second surface 12 increases the farther away from the incident surface 10. If the optical axis Ax1 is inclined with respect to the second surface 12 in this manner, as shown in FIG. 14B, it becomes more difficult for the light incident on the incident surface 10 to reach the end surface 13. As a result, it becomes easier to efficiently emit light from the second surface 12 while suppressing leakage of light from the end surface 13.

In addition, in this modified example, as shown in FIG. 14B, the light emitted from the second surface 12 is not emitted in a direction perpendicular to the second surface 12 (Z-axis direction), but is emitted obliquely with respect to the normal to the second surface 12. That is, in this modified example, as in the first modified example shown in FIG. 13A, the light ray incident on the second surface 12 via the direct optical path L1 follows an optical path inclined with respect to the Z-axis, and therefore is incident obliquely on the second surface 12.

In this way, the light emitted from the second surface 12 through the direct optical path L1 is not limited to being emitted in a direction perpendicular to the second surface 12, and may be inclined at an appropriate angle with respect to the normal to the second surface 12. Furthermore, the direction of the light emitted from the second surface 12 through the direct optical path L1 may or may not be uniform across the entire area of the second surface 12. If the direction of the light emitted from the second surface 12 is not uniform across the entire area of the second surface 12, the light will be emitted in different directions for each part of the second surface 12.

In particular, when the optical system 100B including the light guide member 1 is applied to a head-up display mounted on the moving body B1, it is preferable that the light distribution from the light guide member 1 is controlled to match the optical system 320, as described above. In other words, it is preferable to widen the light emitted from the optical system 100B in the range entering the optical system 320 to match the optical system 320. That is, it is preferable that the viewing angle of the emitted light is narrow, that is, the directivity is high, at each portion of the second surface 12, which is the exit surface of the light guide member 1, to match the optical system 320. On the other hand, it is preferable that the direction of the emitted light is different for each portion of the second surface 12, which is the exit surface of the light guide member 1, to match the optical system 320.

However, the fact that the light emitted from the second surface 12 through the direct optical path L1 is inclined with respect to the normal to the second surface 12 does not presuppose a configuration in which the optical axis Ax1 is inclined with respect to the second surface 12. In other words, in a case in which the optical axis Ax1 is parallel to the second surface 12 as in embodiment 1, the light emitted from the second surface 12 through the direct optical path L1 may be inclined at an appropriate angle with respect to the normal to the second surface 12. Conversely, in a configuration in which the optical axis Ax1 is inclined with respect to the second surface 12, the light emitted from the second surface 12 through the direct optical path L1 may be emitted in a direction perpendicular to the second surface 12.

(3.3) Third Modification The optical control body 2C according to the third modification differs from the optical system 100 according to the first embodiment in that it has a symmetrical shape in the thickness direction (Z-axis direction) as shown in FIG. 15 .

That is, in this modified example, the surface of the light control body 2C facing the light source 4 has a symmetrical shape in one direction (Z-axis direction) perpendicular to the axis facing the light source 4 (here, normal line L21 of the main incident surface 211). In other words, the entrance lens 21, which is the surface of the light control body 2C facing the light source 4, has a symmetrical shape. Specifically, the entrance lens 21 has a secondary incident surface 212 around the entire circumference of the main incident surface 211. The secondary incident surface 212 is divided into multiple (here, eight) lens surfaces 201 to 208.

(3.4) Fourth Modification An illumination system 200 using the optical system 100 according to the fourth modification differs from the illumination system 200 according to the first embodiment in that the illumination system 200 is arranged in parallel with the display 5, as shown in FIGS. 16A and 16B .

That is, in this modified example, the second surface 12 of the light-guiding member 1, which is the emission surface of the lighting system 200, is arranged parallel to the back surface of the display 5. However, with such an arrangement, the second surface 12 is inclined with respect to the horizontal plane, and the light emitted straight from the second surface 12 is emitted diagonally upward from the image display unit 310, as shown in FIG. 16A. Therefore, as shown in FIG. 16B, it is preferable to change the shape of the light distribution control unit 14 provided on the second surface 12 and control the light distribution of the light emitted from the second surface 12 with the light distribution control unit 14. That is, according to the light distribution control unit 14 as shown in FIG. 16B, the light emitted from the second surface 12 is emitted upward from the image display unit 310.

(3.5) Fifth Modification As shown in FIGS. 17A and 17B, an optical system 100 according to a fifth modification differs from the optical system 100 according to the first embodiment in the configuration of a light distribution control unit 14A (or 14B).

In the example of FIG. 17A, the light distribution control unit 14A includes a lens array. The lens array here is a type of multi-lens consisting of a group of multiple small lenses. In the light distribution control unit 14A, multiple small lenses are arranged in a matrix so that multiple small lenses are lined up in the vertical direction (Y-axis direction) and horizontal direction (X-axis direction) of the second surface 12. Each of the multiple small lenses may be a convex lens or a concave lens.

In the example of FIG. 17B, the light distribution control unit 14B includes a Fresnel lens. The Fresnel lens here is a lens in which a single lens is divided into concentric regions, thereby minimizing the amount of protrusion (or recession) in the lens. As an example here, the light distribution control unit 14B is a Fresnel lens in which a convex lens is divided into concentric regions around the center of the second surface 12.

(3.6) Sixth Modification As shown in FIGS. 18A to 20B, an optical system 100 according to a sixth modification has prisms 3B, 3C, 3D, 3E, 3F, and 3G whose shapes differ from those of the optical system 100 according to the first embodiment.

In the example of FIG. 18A, the multiple prisms 3B are arranged so as to line up along an arc when viewed from one side in the Z-axis direction. Here, the multiple prisms 3B are arranged in an arc shape that is convex on the opposite side to the entrance surface 10. In other words, in this modified example, at least some of the prisms 3B are inclined with respect to the entrance surface 10 when viewed from the direction in which the first surface 11 and the second surface 12 are lined up (the Z-axis direction).

In the example of FIG. 18B, the multiple prisms 3C included in the even-numbered rows and the multiple prisms 3C included in the odd-numbered rows are positioned so that their respective longitudinal ends (X-axis direction) do not overlap in the Y-axis direction. With this arrangement, the multiple prisms 3C are lined up with a small gap in the X-axis direction when viewed from the entrance surface 10. The multiple prisms 3C arranged in this manner may also be arranged to line up along an arc when viewed from one side in the Z-axis direction, as in the example of FIG. 18A.

In the example of FIG. 19A, the multiple prisms 3D are each formed in a straight line parallel to the X-axis when viewed from one side in the Z-axis direction. In the example of FIG. 19A, the multiple prisms 3D are formed on the first surface 11 of the light-guiding member 1 so as to be lined up at intervals in the Y-axis direction. In other words, in the example of FIG. 19A, the prisms 3D are arranged so as to be lined up in the direction in which light is incident on the entrance surface 10 (the Y-axis direction).

In the example of FIG. 19B, the multiple prisms 3E are each formed in a curved shape that extends in an arc when viewed from one side in the Z-axis direction. Here, the prisms 3E are formed in an arc shape that is convex on the opposite side to the incident surface 10. In the example of FIG. 19B, the multiple prisms 3E are formed on the first surface 11 of the light-guiding member 1 so as to be lined up at intervals in the Y-axis direction. In other words, in the example of FIG. 19B, the multiple prisms 3E are arranged so as to be lined up in the direction in which light is incident on the incident surface 10 (the Y-axis direction).

In the example of FIG. 20A, the multiple prisms 3F included in the even-numbered rows and the multiple prisms 3F included in the odd-numbered rows are arranged in positions such that their respective ends in the longitudinal direction (X-axis direction) do not overlap in the Y-axis direction. In addition, the multiple prisms 3F are arranged so as to be aligned in a free curve when viewed from one side in the Z-axis direction. The "free curve" here includes various free curves such as, for example, a C-shape, a U-shape, a J-shape, or an S-shape. Here, the multiple prisms 3F are arranged in a free curve that is convex on the opposite side to the incident surface 10. In other words, in this modified example, at least some of the prisms 3F are inclined with respect to the incident surface 10 when viewed from the direction in which the first surface 11 and the second surface 12 are aligned (the Z-axis direction).

In the example of FIG. 20B, similar to the example of FIG. 20A, the multiple prisms 3G are arranged so as to be aligned in a free-form curve when viewed from one side in the Z-axis direction. Here, the multiple prisms 3G are arranged in a free-form curve that is convex toward the entrance surface 10. In other words, in this modified example, at least some of the prisms 3G are inclined with respect to the entrance surface 10 when viewed from the direction in which the first surface 11 and the second surface 12 are aligned (the Z-axis direction).

In order to achieve a narrow viewing angle in an optical system, it is preferable that the optical path of the light emitted from the second surface 12 is as perpendicular to the second surface 12 as possible. Here, the light emitted by the light source 4 has a narrowed spread angle by the light control body 2. However, in the XY plane, not all of the light incident on the incident surface 10 follows an optical path perpendicular to the incident surface 10, and some of the light follows an optical path spreading in the X-axis direction. Therefore, when the prism 3 is linear and parallel to the X-axis, some of the light incident on the incident surface 10 will be obliquely incident on the reflecting surface 30 of the prism 3 in the XY plane. In this case, the light totally reflected by the reflecting surface 30 of the prism 3 follows an optical path at an angle to the second surface 12, rather than a path perpendicular to the second surface 12, which may make it difficult to achieve a narrow viewing angle.

On the other hand, in the modified examples shown in Figures 18A, 19B, 20A, and 20B, at least a portion of prisms 3B, 3E, 3F, and 3G is inclined with respect to the entrance surface 10 when viewed from the Z-axis direction. In other words, in this modified example, light incident on entrance surface 10 tends to be perpendicular to reflecting surface 30 of prisms 3B, 3E, 3F, and 3G in the X-Y plane. Therefore, in these modified examples, light totally reflected by reflecting surface 30 of prisms 3B, 3E, 3F, and 3G tends to follow an optical path perpendicular to second surface 12, which has the advantage of making it easier to achieve a narrow viewing angle.

In the modified example shown in FIG. 18A, the multiple prisms 3B may be arranged in an arc shape that is convex toward the entrance surface 10. In the modified example shown in FIG. 19B, the prism 3E may be formed in an arc shape that is convex toward the entrance surface 10. Furthermore, as shown in FIGS. 20A and 20B, the multiple prisms 3F and 3G arranged in a free-form curve when viewed from one side in the Z-axis direction may have a shape that is continuous in the longitudinal direction, as shown in FIG. 19B.

21A to 21C, the cross-sectional shapes of prisms 3H, 3I, and 3J of optical system 100 according to the seventh modification are different from those of optical system 100 according to embodiment 1. Figures 21A to 21C are schematic diagrams corresponding to Figure 1B, in which a main part of optical system 100 (area A1 in Figure 1A) is enlarged.

21A, the reflecting surface 30 of the prism 3H is formed in a curved shape, not a flat surface. In the example of FIG. 21A, the reflecting surface 30 of the prism 3H is a convex curved surface that is convex on the side opposite the second surface 12, i.e., the side opposite the incident surface 10, when viewed from one side in the X-axis direction. Here, the reflecting surface 30 of the prism 3H is curved only in a cross section parallel to the Y-Z plane, i.e., a cross section perpendicular to the X-axis, and is linear in a cross section parallel to the X-Y plane, i.e., a cross section perpendicular to the Z-axis. However, this is not limited to the example of FIG. 21A, and the reflecting surface 30 of the prism 3H may be a concave curved surface that is curved so as to be convex on the second surface 12 side, i.e., the incident surface 10 side, when viewed from one side in the X-axis direction. Furthermore, the reflecting surface 30 of the prism 3H may be curved only in a cross section parallel to the X-Y plane, i.e., a cross section perpendicular to the Z-axis, or may be curved in both a cross section parallel to the Y-Z plane and a cross section parallel to the X-Y plane.

In the example of FIG. 21B, the reflecting surface 30 of the prism 3I is formed in a polygonal shape, not a flat surface. The "polygonal surface" here means a surface formed by combining a plurality of planes with different orientations, as if forming a surface of a part of a polyhedron, and is a so-called curved surface. In the example of FIG. 21B, the reflecting surface 30 of the prism 3I is a polygonal surface (convex surface) that is curved so as to be convex on the opposite side to the second surface 12, that is, the opposite side to the incident surface 10, when viewed from one side in the X-axis direction. Here, the reflecting surface 30 of the prism 3I is curved only in a cross section parallel to the Y-Z plane, that is, a cross section perpendicular to the X-axis, and is linear in a cross section parallel to the X-Y plane, that is, a cross section perpendicular to the Z-axis. However, the example of FIG. 21B is not limited to this, and the reflecting surface 30 of the prism 3I may be a polygonal surface (concave surface) that is curved so as to be convex on the second surface 12 side, that is, the incident surface 10 side, when viewed from one side in the X-axis direction. Furthermore, the reflecting surface 30 of the prism 3I may bend only in a cross section parallel to the X-Y plane, i.e., in a cross section perpendicular to the Z axis, or may bend in both a cross section parallel to the Y-Z plane and a cross section parallel to the X-Y plane.

In the example of FIG. 21C, the side 31 of the prism 3J is formed in a curved shape rather than a flat surface. The side 31 is the surface of the inner surface of the prism 3J that intersects with the reflecting surface 30, that is, the surface opposite the incident surface 10 when viewed from the reflecting surface 30. In the example of FIG. 21C, the side 31 of the prism 3J is a concave curved surface that is curved so as to be convex on the opposite side of the reflecting surface 30, that is, the opposite side of the incident surface 10, when viewed from one side in the X-axis direction. Here, the side 31 of the prism 3J is curved only in a cross section parallel to the Y-Z plane, that is, a cross section perpendicular to the X-axis, and is linear in a cross section parallel to the X-Y plane, that is, a cross section perpendicular to the Z-axis. However, the example of FIG. 21C is not limited to this, and the side 31 of the prism 3J may be a convex curved surface that is curved so as to be convex on the reflecting surface 30 side, that is, the incident surface 10 side, when viewed from one side in the X-axis direction. Furthermore, the side surface 31 of the prism 3J may be curved only in a cross section parallel to the X-Y plane, i.e., in a cross section perpendicular to the Z axis, or may be curved in both a cross section parallel to the Y-Z plane and a cross section parallel to the X-Y plane.

Furthermore, the side surface 31 of the prism 3J is not limited to being curved, and may be formed into a polygonal surface, similar to the reflecting surface 30 of the prism 3I in FIG. 21B. In this case, similar to the case of a curved surface, the side surface 31 of the prism 3J may be a polygonal surface (concave surface) bent so as to be convex on the side opposite the reflecting surface 30 when viewed from one side in the X-axis direction, or may be a polygonal surface (convex surface) bent so as to be convex on the reflecting surface 30 side.

As in this modification, the cross section of the prism 3 as viewed from one side in the X-axis direction is not limited to a triangular shape, and any suitable shape can be adopted. Furthermore, the cross-sectional shapes of the prisms 3H, 3I, and 3J described above may be adopted in combination with each other, or may be combined with the shapes of the prisms 3B, 3C, 3D, 3E, 3F, and 3G described in the sixth modification.

If the reflecting surface 30 is curved or polygonal, the distribution of light reflected by the prism 3 (reflecting surface 30) and emitted from the second surface 12, specifically the spread angle or direction of the light, can be controlled by the reflecting surface 30. Therefore, depending on the shape of the prism 3 (reflecting surface 30), it is possible to match the distribution of light emitted from the second surface 12 to the optical characteristics of, for example, the display 5 or the optical system 320. In addition, by adopting an appropriate shape such as a curved or polygonal shape for at least one of the reflecting surface 30 and the side surface 31, it is possible to improve the releasability during molding (manufacturing process) of the light-guiding member 1, thereby improving production efficiency.

(3.8) Other Modifications The first surface 11 may be a surface perpendicular to the incident surface 10, and the second surface 12 may be a surface inclined with respect to the X-Y plane without being perpendicular to the incident surface 10. Furthermore, both the first surface 11 and the second surface 12 may be a surface inclined with respect to the X-Y plane without being perpendicular to the incident surface 10.

The multiple prisms 3 do not have to all have the same shape. For example, the multiple prisms 3 may include multiple types of prisms 3 that are different in the inclination angle θ1 of the reflecting surface 30, the longitudinal dimension of the prism 3, or the depth of the recess as the prism 3 (in other words, the height of the prism 3). In particular, in the display system 300 as a head-up display, in order to make the brightness of the displayed virtual image uniform, it is preferable to uniformize the intensity of the light emitted from the second surface 12, which is the exit surface of the light-guiding member 1. In this case, if the light intensity distribution (strictly speaking, the illuminance distribution) on the first surface 11 is not uniform, it is preferable to uniformize the intensity of the light emitted from the second surface 12 by making the shape of the prism 3 different for each part of the first surface 11. In this way, the multiple prisms 3 may adopt different shapes for each part of the first surface 11.

The light guide member 1 only needs to include the direct optical path L1, and it is not essential that all of the light incident on the incident surface 10 passes through the direct optical path L1. In other words, the light guide member 1 may include an indirect optical path in which, for example, the light is reflected one or more times on the first surface 11 or the second surface 12, and then reflected by the prism 3 and emitted from the second surface 12.

In addition, instead of multiple prisms 3, only one prism 3 may be provided on the first surface 11. In this case, the prism 3 may be formed over the entire surface of the first surface 11 and may have multiple reflecting surfaces 30 with different inclination angles.

In addition, in the first embodiment, the prism 3 is formed by processing the first surface 11 of the light guide member 1, but this is not limited to the above. For example, the prism 3 may be provided on the first surface 11 by attaching a prism sheet on which the prism 3 is formed to the first surface 11. In this case, the prism sheet may have one prism 3 formed thereon, or may have multiple prisms 3 formed thereon.

Furthermore, the prism 3 is not limited to a concave shape with respect to the first surface 11, i.e., a shape recessed from the first surface 11, but may be a convex shape with respect to the first surface 11, i.e., a shape protruding from the first surface 11. Even for the prism 3 that has a convex shape with respect to the first surface 11, various shapes may be adopted, as exemplified in the sixth and seventh modified examples.

The light distribution control unit 14 only needs to control the light distribution of the light extracted from the second surface 12, and may be provided on at least one of the first surface 11 and the second surface 12. That is, in the first embodiment, the light distribution control unit 14 is provided on the second surface 12 as the exit surface, but the present invention is not limited to this configuration. The light distribution control unit 14 may be provided on the first surface 11, or on both the first surface 11 and the second surface 12. In the first embodiment, the light distribution control unit 14 is integrated with the light-guiding member 1 as a one-piece molded product, but the present invention is not limited to this configuration. For example, the light distribution control unit 14 may be provided on the second surface 12 by attaching a light distribution sheet on which the light distribution control unit 14 is formed to the second surface 12.

In addition, the light distribution control unit 14 is not limited to a lens, and may be, for example, a diffusion sheet, a prism, or a diffraction grating.

The moving body B1 on which the display system 300 is mounted is not limited to an automobile (passenger car), but may be, for example, a large vehicle such as a truck or a bus, a motorcycle, a train, an electric cart, construction machinery, an aircraft, or a ship, etc.

The display system 300 is not limited to a configuration that displays a virtual image such as a head-up display. For example, the display system 300 may be a liquid crystal display or a projector device. The display system 300 may also be a display device of a car navigation system, an electronic mirror system, or a multi-information display mounted on the mobile body B11.

In addition, the lighting system 200 is not limited to a configuration used in the display system 300, and may be used for industrial purposes such as resin curing or plant cultivation, or lighting purposes including emergency lights.

In addition, the light control body 2 is not an essential component of the optical system 100 and may be omitted. In other words, the optical system 100 only needs to include the light guide member 1 and the prism 3, and the light control body 2 may be omitted as appropriate.

(Embodiment 2)
22A to 22D, the optical system 100C according to this embodiment differs from the optical system 100 according to the first embodiment in that it includes a plurality of types of prisms 301, 302 having mutually different shapes. Hereinafter, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

That is, in this embodiment, the prisms 301 and 302 are arranged in a line in the direction in which light is incident on the incident surface 10 (Y-axis direction). The multiple prisms 301 and 302 include a first prism 301 and a second prism 302. The first prism 301 and the second prism 302 have different inclination angles θ11 and θ12 of the reflecting surface 30 with respect to the first surface 11. Specifically, the reflecting surface 30 of the first prism 301 is inclined at an inclination angle θ11 with respect to the first surface 11, and the reflecting surface 30 of the second prism 302 is inclined at an inclination angle θ12 with respect to the first surface 11. The inclination angle θ11 is larger than the inclination angle θ12. In other words, the first prism 301 has a larger inclination angle of the reflecting surface 30 with respect to the first surface 11 than the second prism 302.

Here, the first surface 11 includes a first region Z1 and a second region Z3. The first region Z1 is a region in which a plurality of first prisms 301 are arranged. The second region Z3 is a region in which a plurality of second prisms 302 are arranged. In other words, the first prisms 301 and the second prisms 302, which have different shapes, are basically arranged separately in the first region Z1 and the second region Z3. In the first region Z1, as shown in FIG. 22B, a plurality of first prisms 301 are arranged side by side. In contrast, in the second region Z3, as shown in FIG. 22D, a plurality of second prisms 302 are arranged side by side.

The first surface 11 further includes a mixed region Z2 between the first region Z1 and the second region Z3. The mixed region Z2 is a region in which both the first prism 301 and the second prism 302 are mixed. That is, in the mixed region Z2, the first prism 301 and the second prism 302 are mixed, as shown in FIG. 22C.

In this disclosure, "mixed" means to exist intermixed. In other words, in the mixed region Z2, the second prism 302 exists between the first prisms 301 and 301, or the first prism 301 exists between the second prisms 302 and 302. In this way, in the mixed region Z2, the first prism 301 and the second prism 302 exist intermixed. Due to the existence of such a mixed region Z2, the region near the boundary between the first prism 301 and the second prism 302 is not completely divided into the region where the first prism 301 exists (first region Z1) and the region where the second prism 302 exists (second region Z3).

Furthermore, the mixed region Z2 includes a first mixed region Z21 and a second mixed region Z22. The first mixed region Z21 is located on the first region Z1 side as viewed from the intermediate position C10 between the first region Z1 and the second region Z3. The second mixed region Z22 is located on the second region Z3 side as viewed from the intermediate position C10. The density of the first prisms 301 is higher in the first mixed region Z21 than in the second mixed region Z22.

Specifically, as shown in FIG. 22A, the first surface 11 is divided into a first region Z1, a mixed region Z2, and a second region Z3 in the Y-axis direction. The first region Z1, the mixed region Z2, and the second region Z3 are arranged in the order of the first region Z1, the mixed region Z2, and the second region Z3 from the light control body 2 side (the incident surface 10 side). The mixed region Z2 is divided into a first mixed region Z21 and a second mixed region Z22 at its intermediate position C10 in the Y-axis direction. The first mixed region Z21 and the second mixed region Z22 are arranged in the order of the first mixed region Z21, the second mixed region Z22 from the light control body 2 side (the incident surface 10 side).

The first prisms 301 are arranged at a higher density in the first mixture region Z21 than in the second mixture region Z22. As an example, assume that multiple prisms 301, 302 are arranged at equal pitch. In this case, the ratio of the second prisms 302 to the first prisms 301 in the second mixture region Z22 is 2:1, whereas the ratio of the second prisms 302 to the first prisms 301 in the first mixture region Z21 is 1:2.

As a modification of the second embodiment, the multiple prisms 301, 302 may further include a third prism in addition to the first prism 301 and the second prism 302. In other words, the multiple prisms 301, 302 may include three or more types of prisms 301, 302 having different inclination angles θ11, θ12 with respect to the first surface 11 of the reflecting surface 30.

The various configurations (including modified examples) described in embodiment 2 can be adopted in appropriate combination with the various configurations (including modified examples) described in embodiment 1.

(summary)
As described above, the optical system (100, 100A to 100C) according to the first aspect includes a light guide member (1), a prism (3, 3A to 3J), and a light control body (2, 2B, 2C). The light guide member (1) has an incident surface (10) on which light is incident, and a first surface (11) and a second surface (12, 12A) facing each other. The second surface (12, 12A) of the light guide member (1) is an exit surface of the light. The prism (3, 3A to 3J) is provided on the first surface (11) and reflects light passing through the inside of the light guide member (1) toward the second surface (12, 12A). The light control body (2, 2B, 2C) is located between the light source (4) and the incident surface (10). The light control body (2, 2B, 2C) controls the light output from the light source (4) and incident on the incident surface (10). The light guide member (1) includes a direct optical path (L1) that causes light incident from the incident surface (10) to be directly reflected by the prisms (3, 3A to 3J) and emitted from the second surface (12, 12A). The light control body (2, 2B, 2C) has a shape conversion function that converts a shape projected onto a projection surface (S1) parallel to the incident surface (10) from a first shape (F1) of light output from the light source (4) to a second shape (F2) of light incident on the incident surface (10).

According to this aspect, it is possible to control the range within the light-guiding member (1) that the light incident from the incident surface (10) reaches, regardless of the first shape (F1) that is the shape of the light output from the light source (4). In other words, the range within the light-guiding member (1) that the light incident from the incident surface (10) reaches is due to the second shape (F2) that is the shape of the light that is incident on the incident surface (10). In addition, the optical system (100, 100A to 100C) can change its shape from the first shape (F19) to the second shape (F2). Therefore, this optical system (100, 100A to 100C) can control the light incident from the entrance surface (10) so that the light reaches a relatively wide area inside the light-guiding member (1). As a result, in the optical system (100, 100A to 100C), it becomes easier for the light to reach the entire first surface (11), and it becomes easier to extract the light uniformly from the entire second surface (12, 12A), which is the exit surface.

In the optical system (100, 100A to 100C) according to the second aspect, in the first aspect, the circumscribing circle of the second shape (F2) is larger than the circumscribing circle of the first shape (F1).

According to this aspect, the second shape (F2) is enlarged compared to the first shape (F1), making it easier to improve the light extraction efficiency.

The optical system (100, 100A to 100C) according to the third aspect is the first or second aspect, in which the second shape (F2) is a shape in which at least one corner (F21) is added to the first shape (F1) so as to make the first shape (F1) closer to a polygonal shape.

According to this aspect, the second shape (F2) is enlarged compared to the first shape (F1), making it easier to improve the light extraction efficiency.

The optical system (100, 100A to 100C) according to the fourth aspect is any one of the first to third aspects, in which a plurality of light sources (4) and a plurality of light control bodies (2, 2B, 2C) are provided.

This aspect makes it easier for light from multiple light sources (4) and multiple light control bodies (2, 2B, 2C) to be introduced into the light-guiding member (1).

The optical system (100, 100A-100C) according to the fifth aspect is any one of the first to fourth aspects, in which the light control body (2, 2B, 2C) has a plurality of lens surfaces (201-205) on the surface facing the light source (4).

This aspect makes it easier for light from the light source (4) to be captured by the light control body (2, 2B, 2C).

The optical system (100, 100A to 100C) according to the sixth aspect is any one of the first to fifth aspects, in which the inclination angle of the surface of the light control body (2, 2B, 2C) facing the light source (4) with respect to the facing axis with the light source (4) varies in the circumferential direction around the facing axis.

This aspect makes it easier for light from the light source (4) to be captured by the light control body (2, 2B, 2C).

The optical system (100, 100A to 100C) according to the seventh aspect is any one of the first to sixth aspects, in which the surface of the light control body (2, 2B, 2C) facing the light source (4) has an asymmetric shape in one direction perpendicular to the axis of facing the light source (4).

This aspect makes it easier to make the light control body (2, 2B, 2C) thinner.

The illumination system (200) according to the eighth aspect includes an optical system (100, 100A to 100C) according to any one of the first to seventh aspects, and a light source (4) that outputs light incident on the incident surface (10).

This aspect makes it easier to extract light uniformly from the entire emission surface.

The display system (300) according to the ninth aspect includes the lighting system (200) according to the eighth aspect and a display (5) that receives light emitted from the lighting system (200) and displays an image.

This aspect makes it easier to extract light uniformly from the entire emission surface.

The mobile body (B1) according to the tenth aspect includes the display system (300) according to the ninth aspect and a mobile body (B11) on which the display system (300) is mounted.

This aspect makes it easier to extract light uniformly from the entire emission surface.

The configurations according to the second to seventh aspects are not essential to the optical system (100, 100A to 100C) and may be omitted as appropriate.

REFERENCE SIGNS LIST 1 Light guide member 2, 2B, 2C Light control body 3, 3A to 3J Prism 4 Light source 5 Display 10 Incident surface 11 First surface 12, 12A Second surface 100, 100A to 100C Optical system 200 Illumination system 201 to 205 Lens surface 300 Display system Ax1 Optical axis Ax2 Optical axis B1 Moving body B11 Moving body main body F1 First shape F2 Second shape F21 Corner S1 Projection surface L1 Direct optical path

Claims (12)

a light guide member having an incident surface on which light is incident, and a first surface and a second surface opposed to each other, the second surface being an exit surface of the light;
a prism provided on the first surface and configured to reflect light passing through the inside of the light guiding member toward the second surface;
a light control unit that is located between a light source and the incident surface and controls light that is output from the light source and incident on the incident surface;
the light guide member includes a direct optical path that causes the light incident on the incident surface to be directly reflected by the prism and emitted from the second surface,
an optical axis of the light incident on the incident surface is inclined with respect to the first surface such that a distance to the first surface decreases with increasing distance from the incident surface;
the light control unit has a shape conversion function of converting a shape projected onto a projection plane parallel to the incident surface from a first shape of the light output from the light source to a second shape of the light incident on the incident surface ,
The light control unit includes an entrance lens,
The entrance lens is
a main incidence surface disposed opposite the light source;
a secondary incidence surface located at least partially around the primary incidence surface and oriented in a direction normal to the primary incidence surface;
The optical axis of the light source is inclined with respect to the normal to the main incidence surface.
Optical system. a light guide member having an incident surface on which light is incident, and a first surface and a second surface opposed to each other, the second surface being an exit surface of the light;
a prism provided on the first surface and configured to reflect light passing through the inside of the light guiding member toward the second surface;
a light control unit that is located between a light source and the incident surface and controls light that is output from the light source and incident on the incident surface;
the light guide member includes a direct optical path that causes the light incident on the incident surface to be directly reflected by the prism and emitted from the second surface,
an optical axis of the light incident on the incident surface is inclined with respect to the first surface such that a distance to the first surface decreases with increasing distance from the incident surface;
the light control unit has a shape conversion function of converting a shape projected onto a projection plane parallel to the incident surface from a first shape of the light output from the light source to a second shape of the light incident on the incident surface,
The light control body has a plurality of lens surfaces on a surface facing the light source.
Optical system. a light guide member having an incident surface on which light is incident, and a first surface and a second surface opposed to each other, the second surface being an exit surface of the light;
a prism provided on the first surface and configured to reflect light passing through the inside of the light guiding member toward the second surface;
a light control unit that is located between a light source and the incident surface and controls light that is output from the light source and incident on the incident surface;
the light guide member includes a direct optical path that causes the light incident on the incident surface to be directly reflected by the prism and emitted from the second surface,
an optical axis of the light incident on the incident surface is inclined with respect to the first surface such that a distance to the first surface decreases with increasing distance from the incident surface;
the light control unit has a shape conversion function of converting a shape projected onto a projection plane parallel to the incident surface from a first shape of the light output from the light source to a second shape of the light incident on the incident surface,
An inclination angle of a surface of the light control body facing the light source with respect to an axis facing the light source varies in a circumferential direction around the axis.
Optical system. a light guide member having an incident surface on which light is incident, and a first surface and a second surface opposed to each other, the second surface being an exit surface of the light;
a prism provided on the first surface and configured to reflect light passing through the inside of the light guiding member toward the second surface;
a light control unit that is located between a light source and the incident surface and controls light that is output from the light source and incident on the incident surface;
the light guide member includes a direct optical path that causes the light incident on the incident surface to be directly reflected by the prism and emitted from the second surface,
an optical axis of the light incident on the incident surface is inclined with respect to the first surface such that a distance to the first surface decreases with increasing distance from the incident surface;
the light control unit has a shape conversion function of converting a shape projected onto a projection plane parallel to the incident surface from a first shape of the light output from the light source to a second shape of the light incident on the incident surface,
The surface of the light control body facing the light source has an asymmetric shape in one direction perpendicular to an axis facing the light source.
Optical system. The circumscribing circle of the second shape is larger than the circumscribing circle of the first shape.
The optical system according to any one of claims 1 to 4. The second shape is a shape obtained by adding at least one corner to the first shape so as to make the first shape closer to a polygonal shape.
The optical system according to any one of claims 1 to 5. The light source and the light control unit are each provided in plurality.
The optical system according to any one of claims 1 to 6. a light guide member having an incident surface on which light is incident, and a first surface and a second surface opposed to each other, the second surface being an exit surface of the light;
a prism provided on the first surface and configured to reflect light passing through the inside of the light guiding member toward the second surface;
a light control unit that is located between a light source and the incident surface and controls light that is output from the light source and incident on the incident surface;
the light guide member includes a direct optical path that causes the light incident on the incident surface to be directly reflected by the prism and emitted from the second surface,
an optical axis of the light incident on the incident surface is inclined with respect to the first surface such that a distance to the first surface decreases with increasing distance from the incident surface;
The light control unit includes an entrance lens,
The entrance lens is
a main incidence surface disposed opposite the light source;
a secondary incidence surface located at least partially around the primary incidence surface and oriented in a direction normal to the primary incidence surface;
the secondary incidence surface has a first lens surface and a second lens surface;
an inclination angle of the first lens surface with respect to the normal line of the main incidence surface is larger than an inclination angle of the second lens surface with respect to the normal line;
Optical system. The surface of the light control body facing the light source has an asymmetric shape in one direction perpendicular to an axis facing the light source.
9. The optical system of claim 8. An optical system according to any one of claims 1 to 9;
The light source outputs light incident on the incident surface.
Lighting system . A lighting system according to claim 10;
a display that receives light emitted from the lighting system and displays an image.
Display system. A display system according to claim 11;
A mobile body having the display system mounted thereon.
Mobile body.

Images