Optical system, lighting system, display system and mobile object

Abstract

To provide an optical system, an illuminating system, a display system, and a moving body that can adjust introduction efficiency of light.SOLUTION: A light guide member 1 comprises an incident surface 10 on which light is incident, and a first surface 11 and a second surface 12 opposed to each other. In the light guide member 1, the second surface 12 is an emitting surface for the light. A prism 3 is provided in the first surface 11, and reflects the light passing through the inside of the light guide member 1, toward the second surface 12. A light control body 2C is located between a light source 4 and the incident surface 10, and controls the light outputted from the light source 4 and to be made incident on the incident surface 10. The light guide member 1 includes a direct light path L1 in which the light incident from the incident surface 10 is directly reflected by the prism 3 and emitted from the second surface 12. In the light control body 2C, an incident lens 21 that is a surface opposed to the light source 4 has a symmetrical shape.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure generally relates to an optical system, an illumination system, a display system, and a moving object. More specifically, the present disclosure relates to an optical system, an illumination system, a display system, and a moving object that control light incident on an entrance surface and emits it from an exit surface. [Background technology]

[0002] 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) in the dashboard, is reflected by the windshield and directed toward the driver, who is the viewer. This allows the user (driver) to view an image such as a navigation image as a virtual image, and the user (driver) views the virtual image as if it were superimposed on a background such as the road surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-142491 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide an optical system, an illumination system, a display system, and a moving body that are capable of adjusting light capture efficiency. [Means for solving the problem]

[0005] An optical system according to an embodiment of the present disclosure includes a light guide member, a prism, and a light control body. The light guide member has an incident surface into 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. An entrance lens, which is an opposing surface of the light control body to the light source, has a symmetrical shape. The light control unit has a shape conversion function for converting a shape projected onto a projection plane parallel to the incident surface from a first shape of light output from the light source to a second shape of light incident onto the incident surface, the circumscribing circle of the second shape being larger than the circumscribing circle of the first shape. 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 into 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 outputs it from the second surface. An incident lens, which is a surface of the light control body facing the light source, has a symmetrical shape. 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 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.

[0006] 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.

[0007] 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.

[0008] A moving body according to one aspect of the present disclosure includes the display system and a moving body body on which the display system is mounted. Effect of the Invention

[0009] The present disclosure has the advantage that the light capture efficiency can be adjusted. [Brief description of the drawings]

[0010] [Figure 1] 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 region A1 in Fig. 1A. [Diagram 2] FIG. 2 is a conceptual diagram showing an outline of a light control unit of the optical system. [Diagram 3] FIG. 3 is a perspective view showing an outline of the optical system of the above embodiment. [Figure 4] FIG. 4 is an explanatory diagram of a display system using the above optical system. [Diagram 5] FIG. 5 is an explanatory diagram of a moving object equipped with the above display system. [Figure 6] Fig. 6A is a plan view of the optical system of the above, Fig. 6B is a front view of the optical system of the above, Fig. 6C is a bottom view of the optical system of the above, and Fig. 6D is a side view of the optical system of the above. [Figure 7] Fig. 7A is a schematic enlarged view of region A1 in Fig. 6C, and Fig. 7B is a cross-sectional view taken along line B1-B1 in Fig. 7A. [Figure 8] Fig. 8A is a perspective view showing the shape of the light control unit of the same embodiment, 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. [Figure 9] Fig. 9A is an explanatory diagram showing the light intensity distribution of the light controller according to the embodiment of the present invention, and Fig. 9B is an explanatory diagram showing the light intensity distribution of a light controller according to a comparative example. [Figure 10] Fig. 10A is an explanatory diagram showing the light intensity distribution of the light controller according to the embodiment of the present invention, and Fig. 10B is an explanatory diagram showing the light intensity distribution of a light controller according to a comparative example. [Figure 11] Fig. 11A is an explanatory diagram showing a light intensity distribution when the light guide member is viewed from one side in the thickness direction when light is emitted from the light control unit to the light guide member according to the embodiment of the present invention, and Fig. 11B is an explanatory diagram showing a light intensity distribution when the light guide member is viewed from one side in the thickness direction when light is emitted from the light control unit to the light guide member according to the comparative example. [Figure 12] Fig. 12A is an explanatory diagram showing a light beam passing through the inside of the light control unit of the above embodiment, Fig. 12B is an explanatory diagram showing a light beam passing through the inside of a light control unit according to a comparative example, and Fig. 12C is an explanatory diagram showing a light beam passing through the inside of a light control unit according to another comparative example. [Figure 13] 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. [Figure 14]Fig. 14A is a side view showing an overview of an optical system according to a second modified example, and Fig. 14B is a cross-sectional view showing an overview of the optical system according to the second modified example. [Figure 15] FIG. 15 is a front view showing an outline of a light control unit according to a third modified example. [Figure 16] 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. [Figure 17] Fig. 17A is a plan view of a main part showing an example of an optical system according to Modification 5. Fig. 17B is a plan view of a main part showing another example of an optical system according to Modification 5. [Figure 18] 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. [Figure 19] Fig. 19A is a schematic diagram showing still another example of a prism according to the sixth modified example, and Fig. 19B is a schematic diagram showing still another example of a prism according to the sixth modified example. [Figure 20] Fig. 20A is a schematic diagram showing still another example of a prism according to the sixth modified example, and Fig. 20B is a schematic diagram showing still another example of a prism according to the sixth modified example. [Figure 21] 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. [Figure 22] 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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (Embodiment 1) (1) Overview First, an overview of an optical system 100 according to this embodiment and an illumination system 200 using the optical system 100 will be described with reference to FIGS. 1A to 3. FIG.

[0012] An optical system 100 according to this embodiment (see FIGS. 1A and 1B) has a function of controlling light incident on an incident surface 10 and causing the light to exit from an exit surface (second surface 12). As shown in FIGS. 1A and 1B, the optical system 100 includes a light-guiding member 1, a light control body 2, and a prism 3.

[0013] The optical system 100 and the light source 4 constitute an illumination system 200. In other words, the illumination 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 a 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.

[0014] Thus, in this embodiment, the optical system 100 further includes the 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 substantial body.

[0015] In this embodiment, the light guiding member 1 has an incident surface 10 on which light is incident, and a first surface 11 and a second surface 12 opposed to each other. The second surface 12 is a surface from which light exits. The prism 3 is provided on the first surface 11. The prism 3 reflects light passing through the inside of the light guiding member 1 toward the second surface 12.

[0016] Here, the light guide member 1 includes a direct optical path L1 (see FIGS. 1A and 1B). The direct optical path L1 is an optical path in which light incident from the incident surface 10 is 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) in which light incident from the incident surface 10 into the light guide member 1 is emitted from the second surface 12 inside the light guide member 1 after only one reflection by 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 by anything other than the prism 3, but reaches the second surface 12 after only one reflection by the prism 3, and is emitted directly to the outside of the light guide member 1 from the second surface 12.

[0017] 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 through the inside of 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 by any part other than the prism 3, and is reflected only once by the prism 3, and is then exited from the light guiding member 1 from the second surface 12.

[0018] 1A, in the optical system 100 according to this embodiment, 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. 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 with increasing distance from the incident surface 10.

[0019] 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 guide 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 guide member 1 facing 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 guide member 1 opposite to the incident surface 10, so that light is less likely to leak from the end surface 13. As a result, the proportion of the 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 can be easily increased, and the light extraction efficiency can be improved.

[0020] In the optical system 100 according to the present embodiment, the light control unit 2 has a shape conversion function as shown in FIG. 2. The shape conversion function is a function of converting a shape projected on a projection plane 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. Here, the projection plane S1 is a "virtual plane" defined inside the light control unit 2 and does not have a real body. As an example, in the present embodiment, the projection plane S1 is the same plane as the incident surface 10. That is, in the present embodiment, the shape of the light projected on the projection plane 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 unit 2 located between the light source 4 and the incident surface 10 of the light guiding member 1.

[0021] This makes it possible to control the range of the light incident from the incident surface 10 inside the light guide member 1, regardless of the first shape F1, which is the shape of the light output from the light source 4. That is, the range of the light incident from the incident surface 10 inside the light guide 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 guide member 1. As a result, in the optical system 100, the light is more likely to reach the entire area of ​​the first surface 11, and it is easier to uniformly extract the light from the entire area of ​​the second surface 12, which is the exit surface.

[0022] 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 light extracted from the second surface 12. In the present embodiment, as an example, 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.

[0023] This allows the light distribution of the light extracted from the second surface 12 of the light guiding member 1 to be controlled by the light distribution control unit 14 provided in the light guiding member 1. In particular, the light guiding member 1 includes a direct light path L1 that causes the light incident into the light guiding member 1 from the incident surface 10 to be emitted from the second surface 12 inside the light guiding 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 guiding 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 guiding 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 guiding of light inside the light guiding member 1, and even if the light distribution control unit 14 is provided in the light guiding member 1, the light guiding performance of the light guiding member 1 is not easily deteriorated. As a result, while light distribution control is possible, light can be efficiently extracted from the second surface 12 to the outside of the light-guiding member 1 through the direct optical path L1, and the light extraction efficiency can be improved.

[0024] As shown in FIG. 2, the optical member 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 unit 22. The optical member 20 outputs light incident on the input lens 21 from the light source 4 from the output unit 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 directed to a 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, if the main input surface 211 is dome-shaped, for example, the normal line L21 of the main input surface 211 is the normal line of the main input surface 211 at its tip (the apex of the dome). The normal L21 of the main incidence surface 211 is a "virtual line" and does not have any substance.

[0025] As a result, the optical axis Ax2 of the light source 4 is inclined with respect to the normal line L21 of the main incident surface 211, so that the light from the light source 4 is incident on the incident lens 21 of the optical member 20 in a manner asymmetric with respect to the normal line L21 of the main incident surface 211. This can disrupt the balance of the light intensity incident from the light source 4 on the main incident surface 211 of the incident lens 21 and the auxiliary incident surfaces 212 positioned therearound. As a result, the light capture efficiency of the optical member 20 can be improved.

[0026] (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.

[0027] (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 perpendicular to each other. The arrows indicating the "X-axis direction", "Y-axis direction", and "Z-axis direction" in the drawings are merely shown for the purpose of explanation and do not have any substance.

[0028] Furthermore, the term "extraction efficiency" in the present disclosure refers to the ratio of the amount of light exiting from the second surface 12 (exit surface) of the light guiding member 1 to the amount of light incident on the incident surface 10 of the light guiding 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 guiding member 1 to the amount of light incident on the incident surface 10 of the light guiding member 1 is larger. As an example, if the amount of light incident on the incident surface 10 of the light guiding member 1 is "100" and the amount of light exiting from the second surface 12 of the light guiding member 1 is "10", the light extraction efficiency of the light guiding member 1 is 10%.

[0029] Furthermore, in the present disclosure, "capture efficiency" refers to the ratio of the amount of light captured by the optical member 20 (light control body 2) to the amount of light output from the light source 4. In other words, the light capture efficiency increases (is larger) when the relative ratio of the amount of light captured by the optical member 20 to the amount of light output from the light source 4 increases. 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 member 20 is "10", the light capture efficiency of the optical member 20 is 10%.

[0030] In addition, the term "optical axis" in this disclosure means 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 rotational symmetry axis of the light emitted from the light source 4.

[0031] In addition, in this disclosure, "parallel" refers to two things being approximately parallel, that is, two things being strictly parallel, as well as a relationship in which the angle between the two things is within a range of a few degrees (for example, less than 5 degrees).

[0032] In addition, in this disclosure, "orthogonal" refers to a relationship in which the two elements are approximately orthogonal, that is, the two elements are strictly orthogonal, as well as the angle between the two elements being within a range of a few degrees (for example, less than 5 degrees) of 90 degrees.

[0033] (2.2) Display System First, the display system 300 will be described with reference to FIGS.

[0034] As shown in FIG. 4, the lighting system 200 according to this embodiment constitutes a display system 300 together with a display device 5. In other words, the display system 300 according to this embodiment includes the lighting system 200 and the display device 5. The display device 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, a symbol, a letter, a number, a design, a photograph, or the like, or a combination of these. Images displayed by the display system 300 include videos (moving images) and still images (still images). Furthermore, the "video" includes an image composed of a plurality of still images obtained by stop motion photography or the like.

[0035] 5, the display system 300 according to this embodiment constitutes a moving body B1 such as an automobile together with a moving body B11. In other words, the moving body B1 according to this embodiment includes the display system 300 and the moving body B11. The moving body B11 is equipped with the display system 300. As an example in this embodiment, the moving body B1 is an automobile (passenger car) driven by a person. In this case, a user U1 who views the image displayed on the display system 300 is a passenger of the moving body B1, and as an example in this embodiment, it is assumed that the driver of the automobile serving as the moving body B1 is the user U1.

[0036] In this embodiment, the display system 300 is used, for example, in a head-up display (HUD) mounted on the moving body B1. The display system 300 is used, for example, 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. The driving information of the moving body B1 includes, for example, navigation-related information that displays a driving route, and information related to ACC (Adaptive Cruise Control) that keeps the driving speed and inter-vehicle distance constant.

[0037] 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.

[0038] 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, and the like are accommodated in the housing 340. The housing 340 is attached to a dashboard B13 of the mobile body B11. Light reflected by a second mirror 322 (described later) of the optical system 320 is emitted to a reflecting member (windshield B12) through an opening on the upper surface of the housing 340, and the light reflected by the windshield B12 is collected in the eye box C1. The reflecting member is not limited to the windshield B12, and may be realized by, for example, a combiner or the like arranged on the dashboard B13 of the mobile body B11.

[0039] 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 the present 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 reflecting 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 image (virtual image) that the display system 300 can display includes a virtual image E1 superimposed along the traveling surface D1 of the moving body B1 and a virtual image drawn three-dimensionally along a plane PL1 perpendicular to the traveling surface D1.

[0040] 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 that allows the user U1 to view a virtual image of a stereoscopically drawn object by projecting images having parallax to the left and right eyes of the user U1.

[0041] 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 by receiving light emitted from the illumination system 200. That is, the illumination system 200 emits light from behind the display 5 toward 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.

[0042] 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.

[0043] The image display unit 310 is accommodated 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 to the user U1, that is, 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.

[0044] 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 collected in the eye box C1. That is, 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.

[0045] The optical system 320 focuses light output from the display surface 312 of the image display unit 310 onto 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.

[0046] 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.

[0047] 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 one or more processors execute programs recorded in one or more memories or storage units 334 of the computer system, thereby realizing functions of the control unit 330 (for example, functions of the drawing control unit 331, the image data creation unit 332, the output unit 333, etc.). The programs are recorded in advance in one or more memories or storage units 334 of the computer system. The programs may be provided through an electric communication line, or may be provided by recording them in a non-transitory recording medium such as a memory card, an optical disk, or a hard disk drive that is readable by the computer system.

[0048] 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 described, the display system 300 is used to display driving support 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).

[0049] 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 in, for example, an advanced driving system (ADAS: Advanced Driver Assistance System). 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 surrounding state of 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 surrounding state of the moving body B1 include an image sensor for photographing the surroundings of the moving body B1, a millimeter wave radar, a LiDAR (Light Detection and Ranging), etc.

[0050] Based on a detection signal input from the sensor 350, the rendering control unit 331 acquires one or more image data for displaying information related to the detection signal from the storage unit 334. Here, when multiple types of information are to be displayed on the image display unit 310, the rendering control unit 331 acquires multiple image data for displaying the multiple types of information. Furthermore, based on the detection signal input from the sensor 350, the rendering control unit 331 obtains position information related to a position at which a virtual image is to be displayed in a target space where the virtual image is to be displayed. Then, the rendering control unit 331 outputs the image data and the position information of the virtual image to be displayed to the image data creation unit 332.

[0051] 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.

[0052] 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, whereby an image (virtual image) is displayed by the display system 300. In this manner, the image (virtual image) displayed by the display system 300 is visually recognized by the user U1.

[0053] (2.3) Optical System Next, the optical system 100 will be described with reference to FIGS. 1A to 3 and 6A to 7B.

[0054] 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.

[0055] In this embodiment, the optical system 100 constitutes an illumination system 200 together with a plurality of light sources 4. That is, the illumination system 200 according to this embodiment includes the optical system 100 and a plurality of light sources 4.

[0056] Since the multiple light control bodies 2 adopt a common configuration, unless otherwise specified below, the configuration described for one light control body 2 also applies to the other light control bodies 2. Furthermore, since the multiple prisms 3 adopt a common configuration, unless otherwise specified below, the configuration described for one prism 3 also applies to the other prisms 3. Furthermore, since the multiple light sources 4 adopt a common configuration, unless otherwise specified below, the configuration described for one light source 4 also applies to the other light sources 4.

[0057] 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 the present 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) having a certain area, but ideally, it can be considered as a point light source that emits light from one point on its surface. Therefore, in the following, the light source 4 will be described assuming that it is an ideal point light source.

[0058] 2, the light source 4 is disposed to face the incident surface 10 of the light guiding member 1 with a predetermined gap therebetween. The light control body 2 is located between the light source 4 and the incident surface 10 of the light guiding member 1.

[0059] In this embodiment, the light control body 2 is integrated with the light guide member 1. In the present disclosure, "integral" means that a plurality of elements (parts) can be physically handled as one unit. In other words, "a plurality of elements are integrated" means that the plurality of elements are integrated into one and can be handled as one member. In this case, the plurality of elements may be in an inseparable integral relationship, such as an integrally molded product, or the plurality of elements that are separately created 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.

[0060] More specifically, in this embodiment, as described above, the light guiding member 1 and the light control body 2 are integrated as an integrally molded product. That is, in this embodiment, the light guiding 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 guiding member 1 is a "virtual surface" defined inside the integrally molded product of the light guiding member 1 and the light control body 2, and does not have a physical entity.

[0061] Here, the multiple light sources 4 are arranged to be lined up at predetermined intervals in the X-axis direction, as shown in Fig. 3. The multiple light sources 4 correspond one-to-one to the multiple light control bodies 2. That is, the multiple light control bodies 2 are also arranged to be lined up in the X-axis direction, similar to 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.

[0062] The light guide member 1 is a member that takes in light from a light source 4 from an incident surface 10 into the light guide member 1 and guides the light through the light guide member 1 to a second surface 12 that is an 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 having a certain degree of thickness.

[0063] As described above, the light guide member 1 has the incident surface 10 on which light is incident, and the first surface 11 and the second surface 12 (exit surface) opposed to each other. Furthermore, the light guide member 1 has an end surface 13 opposed to the incident surface 10.

[0064] Specifically, in this embodiment, as shown in FIGS. 6A to 6D, the light guide member 1 has a rectangular plate shape, 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. One of the four end surfaces (circumferential surfaces) of the light guide member 1 is the incident surface 10. That is, 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. Both surfaces in the thickness direction (Z-axis direction) of the light guide member 1 respectively constitute the first surface 11 and the second surface 12. Furthermore, both surfaces in the short side direction (Y-axis direction) of the light guide member 1 respectively constitute the incident surface 10 and the end surface 13.

[0065] Thus, one of the two end faces of the light guiding member 1 facing each other in the Y-axis direction (the left face in FIG. 1A) is an incident face 10 into which 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 a first face 11 and a 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 an exit face that emits light from the inside of the light guiding member 1 to the outside. Therefore, when light enters the light guiding member 1 from one end face that is the incident face 10, the second face 12 that is the exit face emits light.

[0066] In this embodiment, the second surface 12 is a plane parallel to the XY plane. The incident surface 10 is a plane parallel to the XZ plane. The "XY plane" here is a plane including the X-axis and the Y-axis and perpendicular to the Z-axis. Similarly, the "XZ plane" here is a plane including the X-axis and the Z-axis and 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.

[0067] On the other hand, the first surface 11 is not parallel to the XY plane, but is a plane inclined with respect to the XY plane. That is, the first surface 11 and the incident surface 10 are not perpendicular to each other. Specifically, the first surface 11 is inclined with respect to the XY plane so as to approach the second surface 12 as it moves away from the incident surface 10. That is, in this embodiment, the first surface 11 and the second surface 12 are inclined with respect to each other.

[0068] In this embodiment, the second surface 12 is provided with a light distribution control unit 14. The light distribution control unit 14 includes a lens. In this embodiment, as an example, the light distribution control unit 14 includes a cylindrical lens. The light distribution control unit 14 will be described in detail in the section "(2.7) Light Distribution Control Unit."

[0069] 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 the light toward the incident surface 10 to make the light 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 so as 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 as an ideal point light source is controlled by the light control body 2 to be ideal parallel light.

[0070] Although details will be described in the section "(2.4) Oblique Light Entry", in this embodiment, as shown in Fig. 1A, the optical axis Ax1 of 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.

[0071] 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 portion constituting the incident surface 10 of the light-guiding member 1. That is, in this embodiment, the light control bodies 2 are integral with the light-guiding member 1. As already described, the multiple light control bodies 2 correspond one-to-one to the multiple light sources 4, respectively. Therefore, the multiple light control bodies 2 each control the spread angle of 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".

[0072] 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 incident light. Of course, the prisms 3 are not limited to a configuration in which all incident light is totally reflected, and may also include a configuration in which a portion of light passes through the inside of the prism 3 without being totally reflected.

[0073] In the light guiding member 1, most of the light incident from the incident surface 10 is not reflected at a portion of the first surface 11 or the second surface 12 other than the prism 3, and is reflected by the prism 3 to be emitted from the second surface 12. In other words, the light guiding member 1 includes a direct optical path L1 through which the light incident from the incident surface 10 is directly reflected by the prism 3 and emitted from the second surface 12.

[0074] 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 enlarged end view of a region A1 in FIG. 1A.

[0075] 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 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. Moreover, 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.

[0076] 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 an area A1 in Figure 6C is enlarged. Figure 7B is a diagram showing a schematic end face of line B1-B1 in Figure 7A. Although Figure 7A shows only a part of the first surface 11, in reality, the multiple prisms 3 are formed over substantially the entire area of ​​the first surface 11.

[0077] 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 arranged at intervals in the Y-axis direction as well. If the rows of the prisms arranged in the X-axis direction are the first row, the second row, the third row, etc., counting from the incident 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 such 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 incident surface 10, and the light incident on the light-guiding member 1 from the incident surface 10 is reflected by any one of the prisms 3.

[0078] 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 in 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 recessed portion of 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 direction in which the 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 on the reflecting surface 30 of the prism 3 is the same regardless of which prism 3 the light is incident on among the multiple prisms 3. 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.

[0079] Furthermore, as an example, the depth of the recesses of the prisms 3 (in other words, the height of the prisms 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 recesses of the prisms 3 is a dozen μm, and the pitch in the Y-axis direction of the multiple prisms 3 is a hundred and several tens of μm.

[0080] The light emission principle of the optical system 100 of this embodiment will be described below with reference to FIGS. 1A and 1B.

[0081] 1A, the light emitted from the light source 4 passes through the corresponding light control body 2, whereby the spread angle of the light 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.

[0082] As already described, the optical axis Ax1 of the light incident through the incident surface 10 of the light guiding member 1 is inclined with respect to the first surface 11 such that the distance to the first surface 11 decreases with increasing distance 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 and the end surface 13 of the light guiding member 1 opposite to the incident surface 10.

[0083] 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 along which the light incident from the incident surface 10 is 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.

[0084] Here, in this embodiment, as described above, the inclination angle θ1 of the reflecting surface 30 of the multiple prisms 3 is the same angle. 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, in any of the multiple prisms 3, the direction of the light reflected by the reflecting surface 30 is the same. Therefore, in this embodiment, all the light reaching 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 reaching the second surface 12 on the direct optical path L1 is incident on the second surface 12 at 90 degrees, that is, perpendicular to the second surface 12.

[0085] In this embodiment, since the multiple prisms 3 are arranged over the entire area of ​​the second surface 12, the light that has passed through the direct optical path L1 as described above is evenly emitted from the entire area of ​​the second surface 12 of the light-guiding member 1. As a result, the entire second surface 12 emits light.

[0086] The advantages of the optical system 100 of this embodiment will be described below with a comparison with a general light-guiding member (light-guiding plate).

[0087] In a typical light-guiding member, light incident from the incident surface of the light-guiding member is guided inside the light-guiding member while being repeatedly reflected multiple times on both surfaces (corresponding to first surface 11 and second surface 12) in the thickness direction of the light-guiding member. Then, a prism provided on one surface (corresponding to first surface 11) in the thickness direction of the light-guiding member breaks the condition of total reflection (i.e., incident angle ≧ critical angle), and light is emitted from the other surface (corresponding to second surface 12) in the thickness direction of the light-guiding member as an exit surface. As a result, even in a typical light-guiding member, the entire exit surface emits light.

[0088] 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 portion 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 broken, and the more likely it is that light will leak from one surface (corresponding to first surface 11) in the thickness direction of the light-guiding member.

[0089] In particular, when an optical system including a light guide member is applied to a head-up display mounted on a moving body B1, as in the display system 300 according to this embodiment, the light guide member is required to have a relatively narrow viewing angle and a large light intensity. That is, in a head-up display, it is preferable that the light distribution is controlled from the light guide member in accordance with the optical system 320, and therefore a narrower viewing angle is required compared to a light guide member for a backlight of a general liquid crystal display. Since it is difficult to narrow the viewing angle with a general light guide member, when a general light guide member is used in a head-up display, light is likely to be emitted in unnecessary directions.

[0090] 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. That is, in the present 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 the present embodiment, unlike a general light guiding member, the condition for total reflection is not broken, so that 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 realized by using the direct optical path L1 while exiting most of the light incident on the incident surface 10 at such a narrow angle.

[0091] 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%. The light extraction efficiency of the light guiding member 1 is more preferably 70% or more, and may further be 80% or more.

[0092] In this way, the light extraction efficiency of the light guide member 1 is improved, and therefore 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 unlikely to leak from the first surface 11, sufficient light extraction efficiency can be achieved without arranging these optical elements on the first surface 11 side of the light guide member 1.

[0093] (2.4) Oblique light incidence Next, a configuration regarding light incidence (light incidence) from the incident surface 10 of the light guide member 1 will be described in detail with reference to FIGS. 1A and 1B. FIG.

[0094] 1A, in the optical system 100 according to this embodiment, the optical axis Ax1 of the light incident from the incident surface 10 is inclined with respect to the first surface 11 such 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 to the incident surface 10 of the light guiding member 1, and therefore 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.

[0095] Specifically, the first surface 11 and the second surface 12 are non-parallel and inclined to each other. That is, as described above, the second surface 12 is a plane parallel to the XY plane, whereas the first surface 11 is not parallel to the XY plane and is inclined to the XY plane. Here, the first surface 11 is inclined to the XY 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 guide 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 guide 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.

[0096] On the other hand, the light incident from the incident surface 10 is controlled by the light control body 2 to become parallel light parallel to the second surface 12. That is, 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 the inclination angle is the same as the inclination angle of the first surface 11 with respect to the XY plane (second surface 12).

[0097] 1A, the light control body 2 has a path generating unit 23 that forms light paths L31, L32, and L33 between the light source 4 and the incident surface 10. The path generating unit 23 extends along a straight line (here, the optical axis Ax1) inclined with respect to the first surface 11 when viewed from the incident surface 10, and forms the light paths L31, L32, and L33 between the light source 4 and the incident surface 10. That is, in this embodiment, the light control body 2 is integral with the light-guiding member 1 as described above.

[0098] In other words, when viewed from the incident surface 10 of the light guiding member 1, the light control body 2 includes a portion (path generating unit 23) that protrudes along the optical axis Ax1 inclined with respect to the first surface 11. The light control body 2 forms optical paths L31, L32, and L33 between the light source 4 and the incident surface 10 at the path generating unit 23. Therefore, the light from the light source 4 passes through the path generating unit 23 of the light control body 2 and enters the incident surface 10 along the optical axis Ax1 inclined with respect to the first surface 11. That is, the light from the light source 4 passes through the inside (path generating unit 23) of the light control body 2 and enters the incident surface 10 of the light guiding member 1. 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.

[0099] 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 toward the first surface 11. At this time, the light is incident on the multiple prisms 3 formed on the first surface 11, and is reflected by the reflecting surfaces 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.

[0100] 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 guide member 1, and is therefore 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 guide 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 guide 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 the 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.

[0101] 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 inclined with respect to the incident surface 10 such 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 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.

[0102] Since the end face 13 has such an inclined surface 131, even if a part of the light incident from the incident surface 10 reaches the end face 13 without being incident on the first surface 11, the light can be emitted from the second surface 12. That is, when a part of the light incident from the incident surface 10 is incident on the inclined surface 131 of the end face 13, the 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 has reached the end face 13 can be effectively extracted from the second surface 12, and the light extraction efficiency can be further improved.

[0103] (2.5) Shape conversion function Next, the shape transforming function of the light control unit 2 will be described in detail with reference to FIG. 2 and FIGS. 8A to 11B.

[0104] That is, in the optical system 100 according to this embodiment, as shown in Fig. 2, the light control unit 2 has a shape conversion function of converting the shape projected on the projection surface S1 parallel to the incident surface 10 from a first shape F1 of the light output from the light source 4 to a 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 of converting the projection shape of the light on the projection surface S1 (here, the incident surface 10) in addition to the collimating function of bringing the light output from the light source 4 closer to parallel light.

[0105] 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 a first shape F1 to a second shape F2, and is then 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.

[0106] 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 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.

[0107] In other words, the second shape F2 is a shape obtained by adding at least one corner F21 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 the projection (illumination) area thereof 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.

[0108] 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 the light is more uniformly incident on the entire area of ​​the incident surface 10. For example, when the light of the first shape F1 based on a circular shape is incident on the incident surface 10, a gap or an overlapping portion is likely to occur between the light incident on the incident surface 10 from two adjacent light sources 4. In contrast, when the light of the second shape F2 based on a quadrangle is incident on the incident surface 10, a gap or an overlapping portion is unlikely to occur between the light incident on the incident surface 10 from two adjacent light sources 4.

[0109] The shape transformation function as described above can be realized, for example, by the configuration of the light control body 2 described below.

[0110] That is, in this embodiment, as shown in Figures 8A to 8C, the light control body 2 (optical member 20) includes 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.

[0111] The entrance lens 21 has a main entrance surface 211 and a secondary entrance surface 212. The main entrance surface 211 is disposed so as to face the light source 4. The secondary entrance surface 212 is oriented toward a normal line L21 of the main entrance surface 211. The secondary entrance surface 212 is located on at least a portion of the periphery of the main entrance surface 211. The secondary entrance surface 212 may be parallel (i.e., not inclined) or inclined with respect to the normal line L21 of the main entrance surface 211.

[0112] Here, the entrance lens 21 takes in the light output from the light source 4 from the main entrance surface 211 and the auxiliary entrance surface 212. Therefore, when passing through the entrance lens 21, at least a part of the light from the light source 4 is refracted at the main entrance surface 211 or the auxiliary entrance surface 212 depending on the angle of incidence of the light to the main entrance surface 211 or the auxiliary entrance surface 212. In this manner, the light control body 2 refracts at least a part of the light incident on the main entrance surface 211 or the auxiliary entrance surface 212, thereby emitting the light toward the entrance surface 10 of the light-guiding member 1.

[0113] The light control body 2 further includes an outer peripheral surface 213. The outer peripheral surface 213 is located on the opposite side to the normal line L21 of the main incident surface 211 when viewed from the auxiliary incident surface 212. The outer peripheral surface 213 totally reflects the light incident from the auxiliary incident surface 212 to the incident surface 10 of the light guiding member 1. That is, at least a part of the light incident from the auxiliary incident surface 212 to the light control body 2 is totally reflected by the outer peripheral surface 213 and is emitted toward the incident surface 10 of the light guiding member 1.

[0114] The light control body 2 has a plurality of lens surfaces 201 to 205 on a surface facing the light source 4. The "facing surface" here means a facing surface, that is, the surface of the light control body 2 facing the light source 4 is a surface of the light control body 2 that faces the light source 4. In the present 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 the main entrance surface 211 and the auxiliary entrance surface 212, and in the present embodiment, as an example, the auxiliary entrance surface 212 is divided into a plurality of lens surfaces 201 to 205. The auxiliary entrance surface 212 is divided into a plurality of (here, five) lens surfaces 201 to 205 in the circumferential direction centered on the axis of the light control body 2 facing the light source 4. The "facing axis" here means a virtual axis extending in the facing direction. That is, the opposing axis of the light control body 2 with respect to the light source 4 is a virtual axis extending from the light control body 2 along a direction in which the light control body 2 faces the light source 4. In the present embodiment, as an example, the opposing axis of the light control body 2 with respect to the light source 4 is a normal line L21 (see FIG. 2) of the main incident surface 211.

[0115] The inclination angle of the surface of the light control unit 2 facing the light source 4 with respect to the axis facing the light source 4 varies in the circumferential direction centered on the axis. Specifically, the surface of the light control unit 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 plurality of lens surfaces 201 to 205 with respect to the axis facing the light source 4 (here, the normal line L21) are not constant in the circumferential direction centered on the axis facing the light source 4. Specifically, the inclination angles of the lens surfaces 202 and 204 with respect to the axis facing the light source 4 are larger than the inclination angles of the lens surfaces 201, 203, and 205 with respect to the axis facing 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 than the lens surfaces 201, 203, and 205.

[0116] Furthermore, the surface of the light control body 2 facing the light source 4 has an asymmetric shape in one direction perpendicular to the axis (here, normal line L21) facing the light source 4. 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.

[0117] According to the configuration described above, a shape conversion function can be realized in the light control body 2, and the range reached by the light incident from the incident surface 10 inside the light-guiding member 1 can be controlled regardless of the first shape F1, which is the shape of the light output from the light source 4.

[0118] 9A to 11B are diagrams showing the results of comparison between the light control unit 2 of the optical system 100 according to this embodiment and a light control unit 2X according to a comparative example. The light control unit 2X according to the comparative example has a secondary incident surface 212 that is not divided into a plurality of lens surfaces 201 to 205, but is composed of one continuous curved surface.

[0119] In Fig. 9A to Fig. 11B, the range where the light from the light source 4 reaches is typically represented by a shaded region (dots). Here, the shaded region 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) in a case where 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) in a case where light is emitted from the light control body 2X according to the comparative example to the light guide member 1. Fig. 11A and Fig. 11B both show the intensity distribution (illuminance distribution) of light incident on the light guide member 1 from one light control body 2, 2X.

[0120] That is, in the light control unit 2 according to this embodiment, as shown in Fig. 9A and Fig. 10A, the light output from the light source 4 enters the light control unit 2 from the entrance lens 21 and spreads over a relatively wide range inside the light control unit 2. In particular, according to the shape conversion function of the light control unit 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 of the main entrance surface 211 when viewed from one of the extension directions of the normal line L21 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 L21) than lens surfaces 201, 203, and 205, the light rays incident on lens surfaces 202 and 204 are refracted so as to have a larger inclination angle with respect to normal L21. As a result, the light incident from lens surfaces 202 and 204 of secondary incident surface 212 can easily reach the corners of light control body 2.

[0121] 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 in 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 line L21 of the primary entrance surface 211, and reaches only within a certain range from the normal line L21. As a result, the light does not easily reach the corners of the light control body 2X, and the range that the light reaches is narrower when viewed from one side in the extension direction of the normal line L21 of the primary entrance surface 211 than in the light control body 2 according to the present embodiment.

[0122] 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, the light reaches a substantially rectangular region when the light guide member 1 is viewed from one side in the thickness direction (Z-axis direction). In contrast, according to the light control body 2X of the comparative example, as shown in FIG. 11B, the light reaches a substantially elliptical region when the light guide member 1 is viewed from one side in the thickness direction (Z-axis direction). Therefore, when light is incident on the light guide member 1 from a plurality of light control bodies 2, in this embodiment, the light is more likely to reach the entire first surface 11 and the light is more likely to be extracted uniformly from the entire second surface 12 than in the comparative example.

[0123] (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.

[0124] That is, the optical member 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 unit 22, as shown in FIG. 2. The optical member 20 outputs light incident on the input lens 21 from the light source 4 from the output unit 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 a 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.

[0125] 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 YZ plane. The "YZ 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.

[0126] More specifically, the optical axis Ax2 of the light source 4 and the normal line L21 of the main incident surface 211 intersect on the surface (light emitting surface) of the light source 4. In other words, the light source 4 is disposed so that the center point of its light emitting surface is located on the normal line L21 of the main incident surface 211. In addition, the light source 4 is held in a position inclined by an inclination angle θ2 toward the first surface 11 side. As a result, the light from the light source 4 is incident on the entrance lens 21 of the optical member 20 in a form asymmetric with respect to the normal line L21 of the main incident surface 211.

[0127] Incidentally, 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 rays emitted from the light source 4 is "100%" and the intensity of each light ray from the light source 4 is expressed as a percentage of the maximum intensity, the light emitted from the light source 4 contains light rays with various intensities, such as 10%, 20%, or 30%. In the following, it is assumed that the intensity of the light ray on the optical axis Ax2 of the light source 4 is the maximum intensity, that is, 100%, and the intensity of the light ray decreases as the angle with respect to the optical axis Ax2 increases.

[0128] As shown in FIG. 12A, the light beams incident on the entrance lens 21 from the light source 4 include 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 lower 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 be lower in intensity than 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.

[0129] Specifically, these light rays are arranged in the order of the principal light ray L11, the first auxiliary light ray L12, and the second auxiliary light ray L13 from the first surface 11 side (the lower side in FIG. 12A) in the Z-axis direction perpendicular to the normal line L21 of the principal entrance surface 211. That is, the principal light ray L11, the first auxiliary light ray L12, and the second auxiliary light ray L13 are arranged from the first surface 11 side in order of decreasing intensity.

[0130] 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. That is, 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%. That is, the intensities of the first auxiliary light ray L12 and the second auxiliary light ray L13 are the same.

[0131] On the other hand, 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, as shown in FIG. 12A. 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%. That is, the intensities of the third auxiliary light beam L14 and the fourth auxiliary light beam L15 are the same.

[0132] 12A, neither the third auxiliary light ray L14 nor the fourth auxiliary light ray L15 is incident on the optical member 20. In other words, the third auxiliary light ray L14 nor the fourth auxiliary light ray L15 reaches 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 smaller intensity than the chief ray L11, the first auxiliary light ray L12, and the second auxiliary light ray L13, the loss caused by not reaching the incident surface 10 is small.

[0133] 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 circumferential surface 213 toward the incident surface 10. As a result, the chief ray L11 is emitted from the emission portion 22 toward the incident surface 10.

[0134] Moreover, the auxiliary incident surface 212 has an asymmetric shape with respect to the normal line L21 of the main incident surface 211. In this embodiment, the incident lens 21 has an asymmetric shape in the Z-axis direction. Specifically, the incident lens 21 has the auxiliary incident surface 212 (lens surfaces 202, 203, 204) only on one side in the Z-axis direction when viewed from the main incident surface 211, and the other side in the Z-axis direction is open.

[0135] That is, light rays with relatively high intensity, including the main 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) has the incident lenses 21 concentrated 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), thereby making it easy to keep the dimension t1 in the Z-axis direction small.

[0136] 12B shows an optical system 100Y as a comparative example including an optical member 20Y, and an illumination system 200Y including the optical system 100Y. In the illumination system 200Y according to this comparative example, the optical member 20Y has a symmetric shape in the Z-axis direction with respect to a normal line L21 of the main incidence surface 211. Specifically, the optical member 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 member 20 according to this embodiment, as viewed from the normal line L21 of the main incidence surface 211.

[0137] 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. That is, 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.

[0138] In such a comparative example, as shown in FIG. 12B, the main 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 main 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 light rays with relatively high intensity, including the main ray L11, the first auxiliary ray L12, and the second auxiliary ray L13, are incident on the incident surface 10 of the light guide member 1. However, since the optical member 20Y according to the comparative example adopts a symmetric shape in the Z-axis direction, the dimension t2 in the Z-axis direction is larger than the dimension t1 of the optical member 20 according to this embodiment.

[0139] 12C shows an optical system 100Z as a comparative example including another optical member 20Z, and an illumination system 200Z including the optical system 100Z. 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 comparative example described above, thereby making the optical member 20Z 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.

[0140] 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. That is, 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.

[0141] In such a comparative example, as shown in Fig. 12C, the main light ray L11 is located on the optical axis Ax2 of the light source 4. In addition, the third auxiliary light ray L14 and the fourth auxiliary light ray L15 are located on both sides of the main light ray L11 in the Z-axis direction. However, the first auxiliary light ray L12 and the second auxiliary light ray L13 leak out from the optical member 20Z and do not enter the incident surface 10 of the light guide 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 light ray L12 and the second auxiliary light ray L13, do not enter the incident surface 10 of the light guide member 1, and the light extraction efficiency is significantly lower than that of this embodiment.

[0142] As described above, in the optical member 20 according to this embodiment, the light capture efficiency of the optical member 20 can be improved while achieving a reduction in size, as compared to the comparative examples in FIGS. 12B and 12C.

[0143] (2.7) Light distribution control section Next, the light distribution control unit 14 will be described in detail with reference to FIG.

[0144] That is, in this embodiment, at least one of the first surface 11 and the second surface 12 has a light distribution control section 14. The light distribution control section 14 controls the light distribution of the light extracted from the second surface 12, which is the emission surface. In this embodiment, as an example, the light distribution control section 14 is provided on the second surface 12. Furthermore, in this embodiment, the light distribution control section 14 is integrated with the light guiding member 1 as a one-piece molded product. That is, in this embodiment, the light guiding member 1 and the light distribution control section 14 are an one-piece molded product and are inseparably integrated.

[0145] In short, in this embodiment, the light guiding member 1 includes a direct optical path L1 that causes light that enters the light guiding member 1 from the incident surface 10 to exit from the second surface 12 inside the light guiding 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 guiding 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 guiding performance of the light guiding member 1 is unlikely to deteriorate.

[0146] Specifically, the light distribution control unit 14 in this embodiment includes a lens. That is, the light distribution control unit 14 has a function of a lens as an optical element for refracting light to diverge or converge. As a result, the light distribution control unit 14 can control the light distribution by refracting the light extracted from the second surface 12, which is the exit surface, to diverge or converge the light.

[0147] 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.

[0148] (3) Variations 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.

[0149] Below, we will list some modified examples of the first embodiment. The modified examples described below can be applied in appropriate combination with the first embodiment.

[0150] (3.1) First Modification As shown in FIGS. 13A to 13C, optical system 100A according to the first modification differs from optical system 100 according to the first embodiment in the inclination angle θ3 of reflecting surface 30 of prism 3A relative to first surface 11.

[0151] 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 modification 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 to some extent, the incident angle θ4 is unlikely 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 to some extent, the light incident on the reflecting surface 30 is 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 an improvement in the light extraction efficiency.

[0152] However, in this modified example, 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. As a result, as shown in Fig. 13A, the light emitted from the second surface 12 is emitted obliquely with respect to the normal to the second surface 12, rather than in a direction perpendicular to the second surface 12 (the Z axis direction).

[0153] 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. That is, 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).

[0154] (3.2) Second Modification An optical system 100B according to the second modification example differs from the optical system 100 according to the first embodiment in that the entire light control body 2B is inclined with respect to the light-guiding member 1, as shown in FIGS. 14A and 14B.

[0155] That is, to realize the configuration described in the section "(2.4) Oblique Light Entry", it is sufficient that the optical axis Ax1 of light incident from the incident surface 10 of the light guiding member 1 is inclined with respect to the first surface 11 such that the distance to the first surface 11 decreases with increasing distance from the incident surface 10. According to this modification, both surfaces in the thickness direction (Z-axis direction) of the light control body 2B are inclined with respect to the light guiding member 1, so that the entire light control body 2B is inclined with respect to the light guiding 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 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.

[0156] In particular, in this modification, as shown in FIG. 14B, the optical axis Ax1 of 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 with increasing distance 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, the light incident on the incident surface 10 is less likely 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.

[0157] 14B, the light emitted from second surface 12 is not emitted in a direction perpendicular to second surface 12 (Z-axis direction) but obliquely with respect to the normal to second surface 12. That is, in this modification, as in the first modification shown in FIG. 13A, the light ray incident on second surface 12 via direct optical path L1 follows an optical path inclined with respect to the Z-axis and is therefore obliquely incident on second surface 12.

[0158] 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 over the entire area of ​​the second surface 12. If the direction of the light emitted from the second surface 12 is not uniform over the entire area of ​​the second surface 12, the light will be emitted in different directions for each part of the second surface 12.

[0159] In particular, when the optical system 100B including the light guiding member 1 is applied to a head-up display mounted on a moving body B1, it is preferable that the light distribution from the light guiding member 1 is controlled in accordance with the optical system 320, as described above. In other words, it is preferable that the light emitted from the optical system 100B is expanded in the range of incidence into the optical system 320 in accordance with 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, in each part of the second surface 12, which is the emission surface of the light guiding member 1, in accordance with the optical system 320. On the other hand, it is preferable that the direction of the emitted light is different for each part of the second surface 12, which is the emission surface of the light guiding member 1, in accordance with the optical system 320.

[0160] 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 the first embodiment, 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.

[0161] (3.3) Third Modification As shown in FIG. 15, the light control unit 2C according to the third modification differs from the optical system 100 according to the first embodiment in that it has a symmetric shape in the thickness direction (Z-axis direction).

[0162] That is, in this modification, the surface of the light controller 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). That is, the incident lens 21, which is the surface of the light controller 2C facing the light source 4, has a symmetrical shape. Specifically, the incident 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 a plurality of lens surfaces 201-208 (here, eight).

[0163] (3.4) Fourth Modification An illumination system 200 using the optical system 100 of the fourth modified example differs from the illumination system 200 of embodiment 1 in that the illumination system 200 is arranged parallel to the display 5, as shown in Figures 16A and 16B.

[0164] That is, in this modification, 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, so that the light emitted straight from the second surface 12 is emitted obliquely 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 by 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.

[0165] (3.5) Fifth Modification As shown in FIGS. 17A and 17B, the optical system 100 according to the fifth modified example differs from the optical system 100 according to the first embodiment in the configuration of the light distribution control unit 14A (or 14B).

[0166] 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 small lenses. In the light distribution control unit 14A, the small lenses are arranged in a matrix such that the small lenses are lined up in multiples in the vertical direction (Y-axis direction) and horizontal direction (X-axis direction) of the second surface 12. Each of the small lenses may be a convex lens or a concave lens.

[0167] 17B, ​​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 to reduce the amount of protrusion (or recession) in the lens. As an example, light distribution control unit 14B is a Fresnel lens in which a convex lens is divided into concentric regions around the center of second surface 12.

[0168] (3.6) Sixth Modification As shown in FIGS. 18A to 20B, the optical system 100 according to the sixth modified example differs from the optical system 100 according to the first embodiment in the shapes of the prisms 3B, 3C, 3D, 3E, 3F, and 3G.

[0169] 18A, the multiple prisms 3B are arranged so as to line up along a circular arc when viewed from one side in the Z-axis direction. Here, the multiple prisms 3B are arranged in a circular arc shape that is convex on the opposite side to the incident surface 10. In other words, in this modification, at least some of the prisms 3B 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 lined up (the Z-axis direction).

[0170] 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 arranged at positions such that their respective ends in the longitudinal direction (X-axis direction) do not overlap in the Y-axis direction. With this arrangement, the multiple prisms 3C are lined up with small gaps in the X-axis direction as viewed from the entrance surface 10. The multiple prisms 3C arranged in this manner may also be lined up along an arc as viewed from one side in the Z-axis direction, as in the example of Fig. 18A.

[0171] In the example of Fig. 19A, the multiple prisms 3D are 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 to be lined up at intervals in the Y-axis direction on the first surface 11 of the light guide member 1. That is, in the example of Fig. 19A, the multiple prisms 3D are provided to be lined up in the direction in which light is incident on the incident surface 10 (the Y-axis direction).

[0172] In the example of Fig. 19B, the multiple prisms 3E are each formed in a curved shape extending in an arc shape 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 guide member 1 so as to be lined up at intervals in the Y-axis direction. That is, in the example of Fig. 19B, the multiple prisms 3E are provided so as to be lined up in the direction in which light is incident on the incident surface 10 (the Y-axis direction).

[0173] 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 at positions such that their 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 shape when viewed from one side in the Z-axis direction. The "free curve" here includes various free curves such as a C-shape, a U-shape, a J-shape, or an S-shape. Here, the multiple prisms 3F are arranged in a free curve shape 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).

[0174] 20B, similarly to the example of FIG. 20A, the multiple prisms 3G are arranged so as to be aligned in a free curve when viewed from one side in the Z-axis direction. Here, the multiple prisms 3G are arranged in a free curve that is convex toward the incident surface 10. In other words, in this modification, at least some of the prisms 3G 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).

[0175] Incidentally, in order to realize 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 perpendicular to the second surface 12 as much 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 is 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 having an angle with respect to the second surface 12, rather than an optical path perpendicular to the second surface 12, so that it may be difficult to realize a narrow viewing angle.

[0176] 18A, 19B, 20A, and 20B, at least a portion of each of the prisms 3B, 3E, 3F, and 3G is inclined with respect to the incident surface 10 when viewed from the Z-axis direction. That is, in this modification, the light incident on the incident surface 10 tends to be perpendicular to the reflecting surface 30 of the prisms 3B, 3E, 3F, and 3G in the XY plane. Therefore, in these modifications, the light totally reflected by the reflecting surface 30 of the prisms 3B, 3E, 3F, and 3G tends to follow an optical path perpendicular to the second surface 12, which has the advantage of making it easier to achieve a narrow viewing angle.

[0177] 18A, the multiple prisms 3B may be arranged in an arc shape that is convex toward the incident 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 incident surface 10. Furthermore, as shown in Figs. 20A and 20B, the multiple prisms 3F, 3G arranged in a free curve shape 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.

[0178] (3.7) Seventh Modification 21A to 21C, optical system 100 according to the seventh modification differs from optical system 100 according to embodiment 1 in the cross-sectional shapes of prisms 3H, 3I, and 3J. 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.

[0179] In the example of FIG. 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 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 3H is curved only in a cross section parallel to the YZ plane, that is, a cross section perpendicular to the X-axis, and is linear in a cross section parallel to the XY plane, that is, a cross section perpendicular to the Z-axis. However, without being limited to the example of FIG. 21A, 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, 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 3H may be curved only in a cross section parallel to the XY plane, that is, a cross section perpendicular to the Z-axis, or may be curved in both a cross section parallel to the YZ plane and a cross section parallel to the XY plane.

[0180] 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 joining 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 side opposite to the second surface 12, i.e., the side opposite 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 YZ plane, i.e., a cross section perpendicular to the X-axis, and is linear in a cross section parallel to the XY plane, i.e., a cross section perpendicular to the Z-axis. However, the reflecting surface 30 of the prism 3I is not limited to the example of FIG. 21B, and may be a polygonal surface (concave 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 3I may be bent only in a cross section parallel to the XY plane, that is, in a cross section perpendicular to the Z axis, or may be bent in both cross sections parallel to the YZ plane and the XY plane.

[0181] In the example of FIG. 21C, the side surface 31 of the prism 3J is formed in a curved shape, not a flat surface. The side surface 31 is a surface of the inner surface of the prism 3J that intersects with the reflecting surface 30, that is, a surface on the opposite side of the incident surface 10 as viewed from the reflecting surface 30. In the example of FIG. 21C, the side surface 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, on the opposite side of the incident surface 10, as viewed from one side in the X-axis direction. Here, the side surface 31 of the prism 3J is curved only in a cross section parallel to the YZ plane, that is, a cross section perpendicular to the X-axis, and is linear in a cross section parallel to the XY 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 surface 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, on the incident surface 10 side, as 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 XY plane, that is, in a cross section perpendicular to the Z axis, or may be curved in both a cross section parallel to the YZ plane and a cross section parallel to the XY plane.

[0182] Furthermore, the side surface 31 of the prism 3J is not limited to being curved, and may be formed into a polygonal surface like the reflecting surface 30 of the prism 3I in Fig. 21B. In this case, like the 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 opposite side to 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.

[0183] As in this modification, the cross section of the prism 3 viewed from one side in the X-axis direction is not limited to a triangular shape, and any appropriate shape can be adopted. Furthermore, the cross-sectional shapes of the prisms 3H, 3I, and 3J described above may be combined 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.

[0184] 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 also possible to improve the mold releasability and improve production efficiency, for example, during molding (manufacturing process) of the light guide member 1.

[0185] (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 XY plane and not 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 XY plane and not perpendicular to the incident surface 10.

[0186] Moreover, the multiple prisms 3 do not all have to 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), etc. 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 emission surface of the light guide 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.

[0187] Furthermore, 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 from the incident surface 10 passes through the direct optical path L1. In other words, the light guide member 1 may include, for example, an indirect optical path in which light is reflected one or more times by the first surface 11 or the second surface 12, and then reflected by the prism 3 to be emitted from the second surface 12.

[0188] Also, 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.

[0189] 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 embodiment. 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, one prism 3 or a plurality of prisms 3 may be formed on the prism sheet.

[0190] Furthermore, the prism 3 is not limited to a concave shape with respect to the first surface 11, that is, a shape recessed from the first surface 11, but may be a convex shape with respect to the first surface 11, that is, a shape protruding from the first surface 11. Even for the prism 3 having a convex shape with respect to the first surface 11, various shapes may be adopted, as exemplified in the sixth and seventh modified examples.

[0191] Moreover, the light distribution control section 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 section 14 is provided on the second surface 12 as an exit surface, but the present invention is not limited to this configuration. The light distribution control section 14 may be provided on the first surface 11, or on both the first surface 11 and the second surface 12. Furthermore, in the first embodiment, the light distribution control section 14 is integrated with the light guide member 1 as an integrally molded product, but the present invention is not limited to this configuration. For example, the light distribution control section 14 may be provided on the second surface 12 by attaching a light distribution sheet on which the light distribution control section 14 is formed to the second surface 12.

[0192] Furthermore, the light distribution control section 14 is not limited to a lens, and may be, for example, a diffusion sheet, a prism, a diffraction grating, or the like.

[0193] Furthermore, 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 two-wheeled vehicle, a train, an electric cart, construction machinery, an airplane, or a ship.

[0194] Moreover, 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. Moreover, the display system 300 may be a display device of a car navigation system, an electronic mirror system, or a multi-information display mounted on the mobile body B11.

[0195] Furthermore, 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.

[0196] Furthermore, the light control body 2 is not an essential component of the optical system 100 and may be omitted. That is, the optical system 100 only needs to include the light guiding member 1 and the prism 3, and the light control body 2 can be omitted as appropriate.

[0197] (Embodiment 2) 22A to 22D, optical system 100C according to this embodiment differs from optical system 100 according to embodiment 1 in that it includes multiple types of prisms 301, 302 that are different in shape from each other. Hereinafter, common reference symbols are used for configurations similar to those of embodiment 1, and descriptions thereof will be omitted as appropriate.

[0198] That is, in this embodiment, the prisms 301, 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, 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, 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 with respect to the first surface 11 at an inclination angle θ11, and the reflecting surface 30 of the second prism 302 is inclined with respect to the first surface 11 at an inclination angle θ12. 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.

[0199] 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. That is, 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.

[0200] 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.

[0201] In the present disclosure, "mixed" means to exist in a mixed state. 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 in a mixed state. Due to the existence of such a mixed region Z2, the region where the first prism 301 exists (first region Z1) and the region where the second prism 302 exists (second region Z3) are not completely divided in two near the boundary between the first prism 301 and the second prism 302.

[0202] Furthermore, the mixture region Z2 includes a first mixture region Z21 and a second mixture region Z22. The first mixture region Z21 is located on the first region Z1 side as viewed from an intermediate position C10 between the first region Z1 and the second region Z3. The second mixture 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 mixture region Z21 than in the second mixture region Z22.

[0203] 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 this order from the light controller 2 side (the incident surface 10 side). The mixed region Z2 is divided into a first mixture region Z21 and a second mixture region Z22 at a middle position C10 in the Y-axis direction. The first mixture region Z21 and the second mixture region Z22 are arranged in this order from the light controller 2 side (the incident surface 10 side).

[0204] In the first mixture region Z21, the first prisms 301 are arranged at a higher density than in the second mixture region Z22. As an example, assume that a plurality of prisms 301, 302 are arranged at equal pitches. 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.

[0205] 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 of the reflecting surface 30 with respect to the first surface 11.

[0206] The various configurations (including modified examples) described in the second embodiment can be adopted in appropriate combination with the various configurations (including modified examples) described in the first embodiment.

[0207] (summary) As described above, the optical system (100, 100A to 100C) according to the first aspect includes a light guide member (1) and a prism (3, 3A to 3J). 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 the light passing through the inside of the light guide member (1) toward the second surface (12, 12A). 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, 3A to 3J) and exit from the second surface (12, 12A). At least one of the first surface (11) and the second surface (12, 12A) has a light distribution control section (14, 14A, 14B) that controls the distribution of light extracted from the second surface (12, 12A).

[0208] According to this embodiment, the light distribution of the light extracted from the second surface (12, 12A) of the light guiding member (1) can be controlled by the light distribution control section (14, 14A, 14B) provided in the light guiding member (1). In particular, the light passing through the direct optical path (L1) enters the light guiding member (1) from the incident surface (10) and is not reflected by any other than the prisms (3, 3A to 3J), and is reflected only once by the prisms (3, 3A to 3J), and is emitted to the outside of the light guiding member (1) from the second surface (12, 12A). Therefore, the shapes of the first surface (11) and the second surface (12, 12A) do not contribute to the guiding of light inside the light guiding member (1), and even if the light distribution control section (14, 14A, 14B) is provided in the light guiding member (1), the light guiding performance of the light guiding member (1) is not easily deteriorated. As a result, while enabling light distribution control, light can be efficiently extracted from the second surface (12, 12A) to the outside of the light-guiding member (1) through the direct optical path (L1), thereby improving the light extraction efficiency.

[0209] In the optical system (100, 100A to 100C) according to the second aspect, in the first aspect, the light distribution control section (14, 14A, 14B) is provided on the second surface (12, 12A).

[0210] According to this embodiment, the light distribution of the light transmitted through the second surface (12, 12A) can be efficiently controlled by the light distribution control section (14, 14A, 14B).

[0211] In the optical system (100, 100A to 100C) according to the third aspect, in the first or second aspect, the light distribution control section (14, 14A, 14B) includes a lens.

[0212] According to this aspect, by providing the light distribution control section (14, 14A, 14B) with a lens function, there is no need to provide a separate lens sheet or the like, and the number of parts can be reduced.

[0213] In the optical system (100, 100A to 100C) according to the fourth aspect, in the third aspect, the light distribution control section (14, 14A, 14B) includes a multi-lens made up of a group of a plurality of small lenses (141).

[0214] According to this aspect, by providing the light distribution control section (14, 14A, 14B) with a multi-lens function, it is not necessary to provide a separate multi-lens sheet or the like, and the number of parts can be reduced.

[0215] In the optical system (100, 100A to 100C) according to the fifth aspect, in the third aspect, the light distribution control section (14, 14A, 14B) includes a Fresnel lens.

[0216] According to this embodiment, the light distribution control section (14, 14A, 14B) can be made thinner.

[0217] In the optical system (100, 100A to 100C) according to the sixth aspect, in any of the first to fifth aspects, the inclination angle (θ1, θ11, θ12) of the reflecting surface (30) of the prism (3, 3A to 3J) 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, 12A) on the direct optical path (L1).

[0218] According to this embodiment, even if the angle of incidence of light incident on the reflecting surface (30) varies to some extent, the angle of incidence is less likely to fall below the critical angle, and the light is more likely to be totally reflected by the reflecting surface (30).

[0219] In the optical system (100, 100A to 100C) according to the seventh aspect, in the sixth aspect, the normal to the second surface (12, 12A) is inclined with respect to the optical axis of the light incident on the second surface (12, 12A) on the direct optical path (L1).

[0220] According to this embodiment, the direction of the light emitted from the second surface (12, 12A) can be adjusted.

[0221] In an optical system (100, 100A to 100C) according to an eighth aspect, in any one of the first to seventh aspects, the prisms (3, 3A to 3J) are arranged side by side in the direction in which light is incident on the entrance surface (10). The prisms (3, 3A to 3J) have the same shape.

[0222] According to this embodiment, since the multiple prisms (3, 3A to 3J) have the same shape, it becomes easier to extract light uniformly from the second surface (12, 12A).

[0223] In the optical system (100, 100A to 100C) according to the ninth aspect, in any one of the first to seventh aspects, the prisms (3, 3A to 3J) are arranged in a line in the direction in which light is incident on the incident surface (10). The plurality of prisms (3, 3A to 3J) include a first prism (301) and a second prism (302). The first prism (301) and the second prism (302) have different inclination angles (θ1, θ11, θ12) with respect to the first surface (11) of the reflecting surface (30).

[0224] According to this embodiment, the plurality of prisms (3, 3A to 3J) have different shapes, which makes it easier to differentiate the light distribution of the light extracted from the second surface (12, 12A).

[0225] In the optical system (100, 100A to 100C) according to the tenth aspect, in the ninth aspect, the first surface (11) includes a first region (Z1) in which a plurality of first prisms (301) are arranged, and a second region (Z3) in which a plurality of second prisms (302) are arranged.

[0226] According to this embodiment, it becomes easier to differentiate the distribution of light extracted from the second surface (12, 12A) between the first region (Z1) and the second region (Z3).

[0227] In the optical system (100, 100A to 100C) according to the eleventh aspect, in the tenth aspect, 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 where both the first prism (301) and the second prism (302) are mixed.

[0228] According to this embodiment, it is easy to prevent a sudden change in the distribution of light extracted from the second surface (12, 12A) at the boundary between the first region (Z1) and the second region (Z3).

[0229] In the optical system (100, 100A to 100C) according to the twelfth aspect, in the eleventh aspect, the mixture region (Z2) includes a first mixture region (Z21) and a second mixture region (Z22). The first mixture region (Z21) is located on the first region (Z1) side as viewed from an intermediate position (C10) between the first region (Z1) and the second region (Z3). The second mixture 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 mixture region (Z21) than in the second mixture region (Z22).

[0230] According to this embodiment, it is easier to prevent a sudden change in the light distribution of the light extracted from the second surface (12, 12A) near the boundary between the first region (Z1) and the second region (Z3).

[0231] An illumination system (200) according to a thirteenth aspect includes an optical system (100, 100A to 100C) according to any one of the first to twelfth aspects, and a light source (4) that outputs light incident on the incident surface (10).

[0232] According to this embodiment, it is possible to improve the light extraction efficiency.

[0233] A display system (300) according to a fourteenth aspect includes the lighting system (200) according to the thirteenth aspect, and a display (5) that receives light emitted from the lighting system (200) and displays an image.

[0234] According to this embodiment, it is possible to improve the light extraction efficiency.

[0235] A moving body (B1) according to a fifteenth aspect includes the display system (300) according to the fourteenth aspect, and a moving body (B11) on which the display system (300) is mounted.

[0236] According to this embodiment, it is possible to improve the light extraction efficiency.

[0237] The configurations according to the second to twelfth aspects are not essential for the optical system (100, 100A to 100C) and can be omitted as appropriate. [Explanation of symbols]

[0238] 1 Light guide member 2,2B,2C Light control body 3,3A~3J Prism 4 light source 5 Display 10 Entrance plane 11 Page 1 12,12A 2nd side 14, 14A, 14B Light distribution control section 30 reflective surface 100,100A~100C Optical System 141 Small Lens 200 Lighting System 300 Display System 301 First Prism 302 Second Prism Ax1 optical axis Ax2 optical axis B1 Mobile B11 Mobile body C10 intermediate position L1 Direct optical path Z1 1st area Z2 mixed area Z3 2nd area Z21 1st mixed area Z22 2nd mixed area θ1, θ11, θ12 Inclination angle

Claims

1. 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 an interior 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 entrance lens, which is a surface of the light control body facing the light source, has a symmetrical shape; 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 circumscribing circle of the second shape is larger than the circumscribing circle of the first shape. Optical system.

2. A light-guiding 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 for light; a prism provided on the first surface and configured to reflect light passing through an interior 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 entrance lens, which is a surface of the light control body facing the light source, has a symmetrical shape; 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 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. Optical system.

3. The entrance lens has a main entrance surface arranged to face the light source and a secondary entrance surface located at least partially around the main entrance surface, The entrance lens has a symmetric shape in one direction perpendicular to the normal line of the main entrance surface.

3. An optical system according to claim 1 or 2.

4. The normal to the main incidence surface is inclined with respect to the optical axis of the light source.

4. The optical system of claim 3.

5. The secondary incidence surface is divided into eight lens surfaces.

5. An optical system according to claim 3 or 4.

6. The secondary incidence surface is oriented normal to the primary incidence surface. The optical system according to any one of claims 3 to 5.

7. An optical system according to any one of claims 1 to 6; The light source outputs light incident on the incident surface. Lighting system.

8. A lighting system according to claim 7, a display that receives light emitted from the lighting system and displays an image. Display system.

9. A display system according to claim 8, A mobile body having the display system mounted thereon. Mobile body.

Images