Optical system, lighting system, display system, and mobile object

Abstract

To improve efficiency of light extraction.SOLUTION: An optical system 100 comprises a light guide plate 1, an optical control body 2, and a prism 3. The light guide plate 1 has an incidence surface 10 that light is incident on, and a first surface 11 and a second surface 12 which face each other, and the second surface 12 is an emission surface for light. The optical control body 2 converges light traveling toward the incidence surface 10, and emits the converged light to the incidence surface 10. A prism 3 is provided on the first surface 11, and reflects light passing in the light guide plate 1 toward the second surface 12. The light guide plate 1 includes a direct optical path through which the light made incident from the incidence surface 10 is directly reflected by the prism 3 to be emitted from the second surface 12.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure generally relates to optical systems, lighting systems, display systems, and moving bodies. More specifically, the present disclosure relates to an optical system, a lighting system, a display system, and a moving body that control light incident from an incident surface and emit the light from an exit surface.

Background Art

[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 a head-up display (HUD) device for an automobile. Projection light, which is image light emitted from the in-vehicle HUD device (optical system) within the dashboard, is reflected by the windshield and directed toward the driver, who is the viewer. As a result, the user (driver) can visually recognize an image such as a navigation image as a virtual image, and visually recognize it as if the virtual image were superimposed on a background such as a road surface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present disclosure is to provide an optical system, a lighting system, a display system, and a moving body that can improve the light extraction efficiency.

Means for Solving the Problems

[0005] An optical system according to one aspect of the present disclosure includes a light guide plate, a light control body, and a prism. The light guide plate has an incident surface on which light is incident, and a first surface and a second surface facing each other, and the second surface is an emission surface of light. The light control body condenses light directed toward the incident surface and emits the condensed light to the incident surface. The prism is provided on the first surface and reflects light passing through the inside of the light guide plate toward the second surface. The light guide plate includes a direct optical path that directly reflects light incident from the incident surface by the prism and emits the light from the second surface. The light control body is integral with the light guide plate. The light control body condenses light that directly enters the light control body from a light source disposed outside the light control body. The incident surface is a virtual plane that is disposed to face the light incident surface of the light control body and is orthogonal to the second surface. The optical axis of the light control body is inclined toward the first surface with respect to the incident surface so that more light travels from the incident surface toward the first surface than from the incident surface toward the second surface in the light guide plate. The light control body is a single optical element. The light incident surface of the light control body is It has a refractive surface and a protrusion. The refractive surface is refracts the light emitted by the light source fold to control the divergence angle of the light . The protrusion is formed at the edge on the side of the first surface and the edge on the side of the second surface of the refractive surface, respectively. The protrusion protrudes toward the light source side from the refractive surface. The protrusion has an inner surface and an outer surface. The outer surface is curved so as to approach the inner surface side more on the light source side. The outer surface constitutes a total reflection surface that totally reflects the light that has entered the inside of the protrusion through the inner surface from the light source and emits the totally reflected light to the incident surface.

[0006] An illumination system according to one aspect of the present disclosure includes the above-described optical system and a light source. The light source emits light to the incident surface through the light control body.

[0007] A display system according to one aspect of the present disclosure includes the above-described illumination system and a display. The display receives the light emitted from the illumination system and displays an image.

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

Advantages of the Invention

[0009] The present invention has an advantage that it can improve the light extraction efficiency.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0011] (1) Overview The optical system 100 (see Figures 1A and 1B) of the present embodiment has a function of controlling the light incident from the incident surface 10 and emitting it from the emission surface (second surface 12). As shown in Figure 1, the optical system 100 includes a light guide plate 1, a light control body 2, and a prism 3. The optical system 100 constitutes an illumination system 200 together with a light source 4. In other words, the illumination system 200 includes the optical system 100 and the light source 4. The light source 4 emits light to the incident surface 10 through the light control body 2.

[0012] The light guide plate 1 has an incident surface 10 where light enters, and a first surface 11 and a second surface 12 that face each other, with the second surface 12 being the light exit surface. In this embodiment, the light guide plate 1 is flat, and the two surfaces facing each other in the thickness direction of the light guide plate 1 are the first surface 11 and the second surface 12, respectively. Also, one of the four side surfaces of the light guide plate 1 is the incident surface 10. That is, the light guide plate 1 is configured such that when light enters from the side surface that is the incident surface 10, the second surface 12, which is the light exit surface, emits surface light.

[0013] The light control body 2 condenses the light traveling toward the incident surface 10 and emits the condensed light to the incident surface 10. In this embodiment, the light emitted from the light source 4 enters the incident surface 10 of the light guide plate 1 through the light control body 2. Then, the light incident on the light control body 2 is controlled to narrow the divergence angle and is emitted toward the incident surface 10. In this embodiment, the light control body 2 controls the divergence angle of the light incident on the light control body 2 so that the optical path of the light emitted to the incident surface 10 approaches an optical path parallel to the second surface 12.

[0014] The prism 3 is provided on the first surface 11 and reflects the light passing through the inside of the light guide plate 1 toward the second surface 12. In this embodiment, a plurality of prisms 3 are provided on the first surface 11. The prism 3 is configured to totally reflect the incident light. Of course, the prism 3 is not limited to the mode of totally reflecting all the incident light, and may also include a mode in which some of the light passes through the inside of the prism 3 without total reflection.

[0015] In the light guide plate 1, most of the light incident from the incident surface 10 is reflected by the prism 3 and exits from the second surface 12 without being reflected at the portion of the first surface 11 or the second surface 12 excluding the prism 3. That is, the light guide plate 1 includes a direct optical path L1 that directly reflects the light incident from the incident surface 10 by the prism 3 and emits it from the second surface 12 (see FIG. 3B).

[0016] As described above, in the present embodiment, light with a controlled divergence angle is directly reflected by the prism 3 provided on the first surface 11 of the light guide plate 1 through the light control body 2 and emitted from the second surface 12. Therefore, in the present embodiment, there is an advantage that the light extraction efficiency can be improved as compared with a mode in which light is emitted from the second surface 12 while repeating total reflection on the first surface 11 and the second surface 12 of the light guide plate 1. The "extraction efficiency" as used in the present disclosure refers to the ratio of the amount of light emitted from the second surface 12 (emission surface) of the light guide plate 1 to the amount of light incident on the incident surface 10 of the light guide plate 1.

[0017] (2) Details Hereinafter, the optical system 100 of the present embodiment and the display system 300 using the optical system 100 will be described.

[0018] (2.1) Display System First, the display system 300 will be described. The display system 300 is used, for example, in a head-up display mounted on a vehicle (mobile body) B1, and is used to display driving support information related to, for example, the speed information, condition information, and driving information of the vehicle B1 in the field of view of the user A1. Examples of the driving information of the vehicle B1 include navigation-related information for displaying a driving route and the like, and ACC (Adaptive Cruise Control)-related information for keeping the driving speed and the inter-vehicle distance constant.

[0019] As shown in FIGS. 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.

[0020] The display system 300 is mounted on the mobile body main body B11 of the vehicle B1, which is a mobile body. That is, the mobile body (vehicle) B1 includes the display system 300 and the mobile body main body B11 on which the display system 300 is mounted.

[0021] The housing 340 is made of, for example, a molded product of synthetic resin. The housing 340 houses an image display unit 310, an optical system 320, a control unit 330, etc. The housing 340 is attached to the dashboard B13 of the moving body main body B11. The light reflected by the second mirror 322 (described later) of the optical system 320 is emitted to the reflecting member (windshield B12) through the opening on the upper surface of the housing 340, and the light reflected by the windshield B12 is condensed on the eyeglass case C1. Note that the reflecting member may be realized by a combiner provided on the moving body main body B11.

[0022] The image display unit 310 includes a display device 311 and a lens array 312 disposed on the display surface 313 of the display device 311. The image display unit 310 has a function of displaying a stereoscopic image by a light field method that shows an object three-dimensionally by reproducing light emitted from an object in an image in a plurality of directions.

[0023] The display device 311 is housed inside the housing 340 with the display surface 314 facing the first mirror 321 (described later). The display surface 314 of the display device 311 has a shape (for example, a rectangular shape) that matches the range of the image projected onto the user A1, that is, the shape of the windshield B12. A plurality of pixels are arranged in an array on the display surface 314 of the display device 311. The plurality of pixels of the display device 311 emit light according to the control of the control unit 330, and an image displayed on the display surface 314 is formed by the light output from the display surface 314 of the display device 311. The display device 311 is realized by a display 5 and an illumination system 200 including an optical system 100. The display 5 is, for example, a liquid crystal display or an organic EL (Electro Luminescence) display, etc., and displays an image by receiving light emitted from the illumination system 200. That is, it can be said that the display system 300 includes the illumination system 200 and the display 5.

[0024] On the display surface 314 of the display device 311, a lens array 312 is arranged. Here, the surface of the lens array 312 becomes the display surface 313 of the image display unit 310. The lens array 312 has a plurality of lenses arranged in an array.

[0025] The image displayed on the display surface 314 of the display device 311 is visually recognized by the user A1 having a viewing point in the eyepiece box C1 through the lens array 312 and the optical system 320. Therefore, the user A1 can visually recognize the virtual image E1 superimposed along the traveling surface D1 of the automobile B1 and the virtual image stereoscopically drawn along the plane PL1 orthogonal to the traveling surface D1.

[0026] Note that the method by which the image display unit 310 stereoscopically displays the virtual image of the object to be stereoscopically drawn is not limited to the light field method. The image display unit 310 may adopt a parallax method in which images having a parallax with each other are projected onto the left and right eyes of the user A1, respectively, so that the user A1 can visually recognize the virtual image of the object to be stereoscopically drawn.

[0027] The optical system 320 condenses the light output from the display surface 313 of the image display unit 310 onto the eyepiece box C1. In the present embodiment, the optical system 320 includes, for example, a first mirror 321 that is a convex mirror, a second mirror 322 that is a concave mirror, and a windshield B12.

[0028] 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 toward the windshield B12. The windshield B12 reflects the light incident from the second mirror 322 and makes it incident on the eyepiece box C1.

[0029] The control unit 330 includes, for example, a computer system. The computer system mainly includes one or more processors as hardware and one or more memories. By executing a program recorded in one or more memories or the storage unit 334 of the computer system by one or more processors, the functions of the control unit 330 (for example, functions such as the drawing control unit 331, the image data creation unit 332, and the output unit 333) are realized. The program is pre-recorded in one or more memories or the storage unit 334 of the computer system. Note that the program may be provided through a telecommunication line, or may be provided by being recorded on a non-transitory recording medium such as a memory card, an optical disk, or a hard disk drive that can be read by the computer system.

[0030] The storage unit 334 is realized by a non-transitory recording medium such as a rewritable non-volatile semiconductor memory, for example. The storage unit 334 stores programs and the like executed by the control unit 330. Also, as already described, the display system 300 of the present embodiment is used to display driving support information related to the speed information, condition information, driving information, etc. of the automobile B1 in the field of view of the user A1. Therefore, the types of virtual images displayed by the display system 300 are predetermined. And image data for displaying virtual images (the virtual image E1 which is an object of planar drawing and the virtual image which is an object of three-dimensional drawing) are pre-stored in the storage unit 334.

[0031] The drawing control unit 331 receives detection signals from various sensors 350 mounted on the automobile B1. The sensor 350 is, for example, a sensor for detecting various types of information used in an advanced driver assistance system (ADAS). The sensor 350 includes, for example, at least one of sensors for measuring the vehicle speed, temperature, remaining fuel, etc. of the automobile B1, an image sensor for photographing the surroundings of the automobile B1, and sensors such as a millimeter wave radar and a LiDAR (Light Detection and Ranging) for detecting objects existing around the automobile B1.

[0032] Based on the detection signal input from the sensor 350, the drawing control unit 331 acquires one or more pieces of image data for displaying information regarding this detection signal from the storage unit 334. Here, when displaying multiple types of information on the image display unit 310, the drawing control unit 331 acquires multiple pieces of image data for displaying the multiple types of information. Also, based on the detection signal input from the sensor 350, the drawing control unit 331 obtains position information regarding the position where the virtual image is to be displayed in the target space where the virtual image is to be displayed. Then, the drawing control unit 331 outputs the image data of the virtual image to be displayed and the position information to the image data creation unit 332.

[0033] Based on the image data and the position information input from the drawing control unit 331, the image data creation unit 332 creates image data for displaying the virtual image to be displayed.

[0034] The output unit 333 outputs the image data created by the image data creation unit 332 to the display device 311, and causes an image based on the created image data to be displayed on the display surface 314 of the display device 311. The image displayed on the display surface 314 is condensed onto the eyebox C1 via the lens array 312 and the optical system 320, and the virtual image is visually recognized by the user A1.

[0035] (2.2) Optical System Next, the optical system 100 will be described with reference to FIGS. 1A to 3B. The optical system 100 includes a light guide plate 1, a plurality of light control bodies 2, and a plurality of prisms 3. The optical system 100 constitutes an illumination system 200 together with a plurality of light sources 4. In the following description, the width direction of the light guide plate 1 (the direction in which the plurality of light sources 4 are arranged in FIG. 2) is the "X direction", and the depth direction of the light guide plate 1 (the direction in which the plurality of prisms 3 are arranged in FIG. 1A) is the "Y direction". Also, in the following description, the thickness direction of the light guide plate 1 (the direction in which the first surface 11 and the second surface 12 are arranged in FIG. 1A) is the "Z direction".

[0036] Note that the arrows indicating the "X direction", "Y direction", and "Z direction" in the drawings are merely for illustrative purposes and do not have a physical entity. Also, the dashed arrows in the drawings conceptually represent the optical paths of the light emitted from the light source 4 and passing through the inside of the light guide plate 1.

[0037] The light source 4 is a solid light-emitting element such as, for example, a light-emitting diode (LED) element or an organic electro-luminescence (OEL) element. In the present embodiment, as shown in FIG. 2, a plurality of light sources 4 are arranged at intervals in the X direction so as to face the incident surface 10 of the light guide plate 1. The plurality of light sources 4 respectively correspond one-to-one with a plurality of light control bodies 2 provided on the incident surface 10 of the light guide plate 1.

[0038] The light guide plate 1 is formed of a light-transmissive material such as, for example, an acrylic resin and has a flat plate shape. One of the two side surfaces (the left surface in FIG. 1A) facing each other in the Y direction of the light guide plate 1 is the incident surface 10 through which the light emitted from the plurality of light sources 4 enters through the plurality of light control bodies 2 respectively. The two surfaces facing each other in the Z direction of the light guide plate 1 are the first surface 11 and the second surface 12 respectively. The first surface 11 is the lower surface in FIG. 1A, and the second surface 12 is the upper surface in FIG. 1A. And the second surface 12 is an emission surface through which the light passing through the inside of the light guide plate 1 is emitted to the outside.

[0039] In the present embodiment, the second surface 12 is a surface orthogonal to the incident surface 10, in other words, a surface parallel to the XY plane. On the other hand, the first surface 11 is not orthogonal to the incident surface 10 and is a surface inclined with respect to the XY plane. Specifically, the first surface 11 is inclined so as to approach the second surface 12 as it moves away from the incident surface 10. That is, in the present embodiment, the first surface 11 and the second surface 12 are inclined with respect to each other.

[0040] The light control body 2 is, for example, a collimator lens, which condenses the light directed toward the incident surface 10 and emits the condensed light to the incident surface 10. Specifically, as shown in FIG. 3A, the light control body 2 has a refracting surface 20 and a total reflection surface 21. The refracting surface 20 refracts a part of the light emitted from the light source 4 and emits the refracted light to the incident surface 10. The total reflection surface 21 totally reflects a part of the light emitted from the light source 4 and emits the totally reflected light to the incident surface 10. In this way, the light control body 2 controls to narrow the divergence angle of the light emitted from the light source 4 by refracting part or all of the light emitted from the light source 4. Therefore, the light control body 2 controls the divergence angle of the light emitted from the light source 4 so that the optical path of the light emitted from the light control body 2 approaches an optical path perpendicular to the incident surface 10, in other words, an optical path parallel to the second surface 12.

[0041] In the present embodiment, as shown in FIG. 2, the plurality of light control bodies 2 are formed to be arranged in the X direction at an end portion constituting the incident surface 10 of the light guide plate 1. That is, in the present embodiment, the light control body 2 is integral with the light guide plate 1. Further, as already described, the plurality of light control bodies 2 respectively correspond one-to-one to the plurality of light sources 4. Therefore, the plurality of light control bodies 2 respectively control the divergence angle of the light emitted from the corresponding light source 4 and emit the light to the incident surface 10.

[0042] The prism 3 is formed on the first surface 11 so that a cross section viewed from the X direction becomes a triangular concave portion by processing an end portion constituting the first surface 11 of the light guide plate 1. As shown in FIG. 1B, the prism 3 has a reflecting surface 30 that reflects the light incident through the inside of the light guide plate 1 toward the second surface 12. Note that FIG. 1B is an enlarged view of a portion surrounded by a dashed-dotted line in FIG. 1A.

[0043] The angle θ1 formed by the reflecting surface 30 and the first surface 11 (i.e., the inclination angle of the reflecting surface 30) is such that the incident angle θ0 of the light incident on the reflecting surface 30 is equal to or greater than the critical angle. That is, the reflecting surface 30 is inclined with respect to the first surface 11 so that the incident light is totally reflected. Further, the inclination angle θ1 of the reflecting surface 30 is set such that the light totally reflected by the reflecting surface 30 is emitted in a direction including a direction substantially perpendicular to the second surface 12. Here, the incident angle θ0 of the light incident on the plurality of prisms 3 is different for each prism 3.

[0044] In the present embodiment, as shown in FIG. 2, the plurality of prisms 3 are each formed in a linear shape parallel to the X direction when viewed from the Z direction. And the plurality of prisms 3 are formed so as to be arranged at intervals in the Y direction at an end portion constituting the first surface 11 of the light guide plate 1. That is, in the present embodiment, the prisms 3 are provided so as to be arranged in a plurality in the direction (Y direction) in which light is incident on the incident surface 10. Specifically, the plurality of prisms 3 are provided at intervals in the Y direction so that the light passing through the inside of the light guide plate 1 and heading toward the first surface 11 is reflected by any one of the plurality of prisms 3.

[0045] Hereinafter, the light emission principle of the optical system 100 of the present embodiment will be described with reference to FIGS. 3A and 3B. First, as shown in FIG. 3A, the light emitted from the light source 4 passes through the corresponding light control body 2, whereby the divergence angle is controlled. Then, the light with the controlled divergence angle is emitted from the light control body 2 toward the incident surface 10 of the light guide plate 1. The optical path of the light emitted from the light control body 2 is an optical path substantially perpendicular to the incident surface 10, in other words, an optical path substantially parallel to the second surface 12. Further, as already described, the first surface 11 is inclined so as to approach the second surface 12 as it moves away from the incident surface 10. For this reason, most of the light incident on the incident surface 10 reaches the first surface 11 without reaching the second surface 12 and the side surface 13 of the light guide plate 1 facing the incident surface 10.

[0046] Then, as shown in FIG. 3B, most of the light incident on the incident surface 10 is totally reflected by the reflecting surface 30 of any one of the plurality of prisms 3 provided on the first surface 11 without being reflected by the first surface 11 and the second surface 12. That is, the light guide plate 1 includes a direct optical path L1 that directly reflects the light incident from the incident surface 10 by the prism 3 and emits it from the second surface 12. Further, in the present embodiment, the direct optical path L1 includes the optical path of the light totally reflected by the prism 3. The light totally reflected by the reflecting surface 30 of the prism 3 travels along an optical path that is almost orthogonal to the second surface 12 and is emitted from the second surface 12. As a result, the entire second surface 12 emits surface light.

[0047] Here, a part of the light incident on the incident surface 10 travels toward the second surface 12 without going toward the first surface 11 and the side surface 13. The light traveling toward the second surface 12 can be totally reflected by the second surface 12. Then, since the light totally reflected by the second surface 12 travels toward the first surface 11, this light is totally reflected by the reflecting surface 30 of any one of the plurality of prisms 3. The light totally reflected by the reflecting surface 30 of the prism 3 travels along an optical path that is almost orthogonal to the second surface 12 and is emitted from the second surface 12, similarly to the light traveling along the direct optical path L1. That is, in the present embodiment, the light guide plate 1 may further include an indirect optical path L2 that reflects the light incident from the incident surface 10 by the second surface 12 and then reflects it by the prism 3 and emits it from the second surface 12.

[0048] Hereinafter, the advantages of the optical system 100 of the present embodiment will be described in comparison with the optical system 400 of the comparative example. The optical system 400 of the comparative example is different from the optical system 100 of the present embodiment in that it does not include a plurality of light control bodies 2 and a plurality of prisms 3, as shown in FIGS. 6A and 6B. Further, the optical system 400 of the comparative example is different from the optical system 100 of the present embodiment in that the first surface 501 is inclined with respect to the second surface 502 so that the light incident on the first surface 501 of the light guide plate 401 is totally reflected.

[0049] In the optical system 400 of the comparative example, the light emitted from the light source 402 enters the incident surface 500 of the light guide plate 401 without controlling the divergence angle. Therefore, in the optical system 400 of the comparative example, the light incident on the incident surface 500 is almost evenly divided into the light traveling toward the first surface 501 and the light traveling toward the second surface 502. And in the optical system 400 of the comparative example, similar to a general light guide plate, the light incident on the incident surface 500 is emitted from the second surface 502 while repeating total reflection at the first surface 501 and the second surface 502. As a result, in the optical system 400 of the comparative example, the entire second surface 502 emits surface light.

[0050] However, the optical system 400 of the comparative example is designed to cause the entire second surface 502 to emit surface light by repeating total reflection of light at the first surface 501 and the second surface 502 of the light guide plate 401. For this reason, the more the number of total reflections of light increases, the easier it is for the total reflection condition (that is, the incident angle ≥ critical angle) to collapse, and the higher the possibility that light leaks from the first surface 501.

[0051] In particular, when applying an optical system to a head-up display mounted on the vehicle B1 as in the display system 300 of the present embodiment, the optical system is required to have a narrow viewing angle and high light intensity as compared with an optical system including a general light guide plate. In order to narrow the viewing angle, it is necessary to reduce the area of the emission surface of the light guide plate, that is, to reduce the size of the light guide plate. However, the smaller the light guide plate is, the shorter the distance (light guide distance) that the light incident on the light guide plate can reach. And the shorter the light guide distance is, the more light leaks from the side surface facing the incident surface without being emitted from the emission surface of the light guide plate, and it becomes difficult to ensure sufficient light intensity (in other words, light extraction efficiency).

[0052] Therefore, in order to ensure sufficient light intensity even in a light guide plate with a short light guiding distance, it is conceivable to incline the first surface 501 of the light guide plate 401 with respect to the second surface 502 as in the optical system 400 of the comparative example. However, as already described, even in the optical system 400 of the comparative example, light easily leaks from the first surface 501, and as a result, it is difficult to ensure sufficient light extraction efficiency.

[0053] On the other hand, in the optical system 100 of the present embodiment, since the light 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 guide plate 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 guide plate 1 directly enters the prism 3 and exits from the second surface 12 without repeating total reflection at the first surface 11 and the second surface 12. For this reason, in the present embodiment, unlike the optical system 400 of the comparative example, the condition of total reflection is not broken, so light hardly leaks from the first surface 11, and as a result, the light extraction efficiency can be improved.

[0054] Note that a part of the light incident on the incident surface 10 of the light guide plate 1 follows the indirect optical path L2, but since the total reflection that occurs before reaching the prism 3 is only the total reflection at the second surface 12, compared with the optical system 400 of the comparative example, the condition of total reflection is less likely to be broken, and light hardly leaks from the first surface 11.

[0055] Thus, the optical system 100 of the present embodiment is designed to avoid the number of total reflections of the light passing through the inside of the light guide plate 1 as much as possible compared with the optical system 400 of the comparative example, so that the light extraction efficiency can be improved.

[0056] In addition, in the present embodiment, the first surface 11 and the second surface 12 are inclined with respect to each other. For this reason, in the present embodiment, the degree of narrowing the spread angle of the light incident on the incident surface 10 by the light control body 2 can be made smaller compared to the case where the first surface 11 and the second surface 12 are parallel to each other. Therefore, in the present embodiment, compared to the case where the first surface 11 and the second surface 12 are parallel to each other, it is not necessary to increase the distance between the light control body 2 and the corresponding light source 4, and as a result, there is an advantage that it is easy to reduce the size of the lighting system 200.

[0057] (3) Modification The above-described embodiment is merely one of various embodiments of the present disclosure. The above-described embodiment can be variously modified according to design and the like as long as the object of the present disclosure can be achieved. Each drawing described in the above-described embodiment is a schematic drawing, and the ratio of the size and thickness of the components in the drawing does not necessarily reflect the actual dimensional ratio.

[0058] Hereinafter, modifications of the above-described embodiment will be listed. The modifications described below can be applied in appropriate combination with the above-described embodiment.

[0059] (3.1) First modification As shown in FIG. 7A, the optical system 100A of the first modification is different from the optical system 100 of the above-described embodiment in that the prism 3 is divided into a plurality (here, three) of small prisms 31. That is, in this modification, the prism 3 has a plurality of small prisms 31 that are divided so as to be spaced apart from each other. In FIG. 7A, only one of the plurality of prisms 3 arranged in the Y direction is shown. Further, in FIG. 7A, only the portion corresponding to one light source 4 and one light control body 2 among one prism 3 is shown.

[0060] The plurality of small prisms 31 are all arranged in an arc shape when viewed from the Z direction. That is, in this modified example, at least a part (small prism 31) of the prism 3 is inclined with respect to the incident surface 10 when viewed from the direction (Z direction) in which the first surface 11 and the second surface 12 are arranged. Further, in this modified example, two or more of the plurality of small prisms 31 are arranged so as to be arranged in a curved shape when viewed from the direction (Z direction) in which the first surface 11 and the second surface 12 are arranged.

[0061] By the way, in order to realize a narrow viewing angle in the 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 from the light source 4 has its divergence angle narrowed by the light control body 2. However, as shown in FIG. 7A, 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 light follows an optical path that spreads in the X direction. Therefore, when the prism 3 is linearly parallel to the X direction as in the above-described embodiment, a part of the light incident on the incident surface 10 is incident on the reflection surface 30 of the prism 3 obliquely in the XY plane. In this case, the light totally reflected by the reflection surface 30 of the prism 3 follows an optical path having an angle with respect to the second surface 12 instead of an optical path perpendicular to the second surface 12, so that it may be difficult to realize a narrow viewing angle.

[0062] On the other hand, in this modified example, at least a part of the prism 3 is inclined with respect to the incident surface 10 when viewed from the Z direction. That is, in this modified example, the light incident on the incident surface 10 is incident on the reflection surface 30 of the small prism 31 almost perpendicularly in the XY plane. For this reason, in this modified example, the light totally reflected by the reflection surface 30 of the small prism 31 easily follows an optical path almost perpendicular to the second surface 12, and as a result, there is an advantage that a narrow viewing angle is easily realized.

[0063] In this modified example, the plurality of small prisms 31 may be arranged as shown in FIG. 7B so that the center of an arc approximating a curved arrangement is located on the side opposite to the light control body 2 with the prism 3 interposed therebetween when viewed from the Z direction.

[0064] Also, in this modified example, the plurality of small prisms 31 may be arranged so as not to be arranged in a curved shape when viewed from the Z direction as shown in FIG. 7C. In this aspect, there is an advantage that the time required for processing to form the plurality of small prisms 31 can be shortened. Further, in this aspect, since the plurality of small prisms 31 are randomly arranged, there is an advantage that unevenness of the light emitted from the second surface 12 can be easily suppressed.

[0065] (3.2) Second modified example As shown in FIGS. 8A and 8B, the optical system 100B of the second modified example is different from the optical system 100 of the above-described embodiment in that the first surface 11 and the second surface 12 of the light guide plate 1 are not inclined with respect to each other, and both are surfaces orthogonal to the incident surface 10. Further, the optical system 100B of this modified example is different from the optical system 100 of the above-described embodiment in that the light source 4 and the light control body 2 are arranged so as to be inclined with respect to the incident surface 10.

[0066] That is, the optical system 100B of this modified example is designed such that most of the light incident on the incident surface 10 is directed toward the first surface 11 by inclining the light source 4 and the light control body 2 with respect to the incident surface 10. Therefore, in this modified example, as in the above-described embodiment, most of the light incident on the incident surface 10 follows the direct optical path L1, so that the light extraction efficiency can be improved without performing processing for providing an inclined surface on the light guide plate 1. Therefore, in this modified example, there is an advantage that the design of the light guide plate 1 is easier compared to the above-described embodiment.

[0067] Note that in FIG. 8B, the light guide plate 1 includes only the direct optical path L1, but may include the indirect optical path L2.

[0068] (3.3) Third modified example The optical system 100C of the third modification example is different from the optical system 100 of the above-described embodiment in that the first surface 11 and the second surface 12 of the light guide plate 1 are not inclined with respect to each other, and both are surfaces orthogonal to the incident surface 10. Further, as shown in FIG. 9, the optical system 100C of this modification example is different from the optical system 100 of the above-described embodiment in that the depths d1, d2, and d3 of the plurality of prisms 3 (here, three prisms 3A, 3B, and 3C) are different from each other. The depths d1, d2, and d3 of the three prisms 3A, 3B, and 3C become deeper as they go in the traveling direction of the light incident on the incident surface 10 (rightward in FIG. 9).

[0069] That is, the optical system 100C of this modification example is designed such that most of the light incident on the incident surface 10 is totally reflected by any one of the plurality of prisms 3 by making the depths of the plurality of prisms 3 different from each other. Therefore, in this modification example, as in the above-described embodiment, most of the light incident on the incident surface 10 follows the direct optical path L1, so that the light extraction efficiency can be improved without performing the process of providing an inclined surface on the light guide plate 1. Therefore, this modification example has the advantage that the design of the light guide plate 1 is easier compared to the above-described embodiment.

[0070] Note that in FIG. 9, the light guide plate 1 includes only the direct optical path L1, but may include the indirect optical path L2.

[0071] (3.4) Other modification examples In the above-described embodiment, the first surface 11 may be a surface orthogonal to the incident surface 10, and the second surface 12 may be a surface inclined with respect to the XY plane without being orthogonal to the incident surface 10. Further, in the above-described embodiment, both the first surface 11 and the second surface 12 may be surfaces inclined with respect to the XY plane without being orthogonal to the incident surface 10.

[0072] In the above-described embodiment, only one prism 3 instead of a plurality of prisms 3 may be provided on the first surface 11. In this case, the prism 3 may be formed over the entire first surface 11 and may have a plurality of reflecting surfaces 30 with different inclination angles from each other.

[0073] In the above-described embodiment, the prism 3 is formed by processing the end portion constituting the first surface 11 of the light guide plate 1, but is not limited to this aspect. 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 may be formed on the prism sheet, or a plurality of prisms 3 may be formed.

[0074] Not limited to the first modification, in the above-described embodiment, the second modification, and the third modification, the prisms 3 may be divided so as to be spaced apart from each other in the X direction. Also, in the first modification, the prism 3 may be connected without being divided into a plurality of small prisms 31.

[0075] (Summary) As described above, the optical system (100, 100A to 100C) according to the first aspect includes a light guide plate (1), a light control body (2), and a prism (3). The light guide plate (1) has an incident surface (10) on which light is incident, and a first surface (11) and a second surface (12) facing each other, and the second surface (12) is a light exit surface. The light control body (2) condenses the light traveling toward the incident surface (10) and emits the condensed light to the incident surface (10). The prism (3) is provided on the first surface (11) and reflects the light passing through the inside of the light guide plate (1) toward the second surface (12). The light guide plate (1) includes a direct optical path (L1) that directly reflects the light incident from the incident surface (10) by the prism (3) and emits it from the second surface (12).

[0076] According to this aspect, there is an advantage that the light extraction efficiency can be improved.

[0077] In the optical system (100, 100A to 100C) according to the second aspect, in the first aspect, the direct optical path (L1) includes the optical path of the light that is totally reflected by the prism (3).

[0078] According to this aspect, there is an advantage that the light extraction efficiency is likely to be improved as compared with the case where the light is not totally reflected by the prism (3).

[0079] In the optical system (100, 100A to 100C) according to the third aspect, in the first or second aspect, the light control body (2) is integrated with the light guide plate (1).

[0080] According to this aspect, there is an advantage that it is easier to control the light incident on the incident surface (10) as compared with the case where the light control body (2) is separate from the light guide plate (1).

[0081] In the optical system (100, 100A) according to the fourth aspect, in any one of the first to third aspects, the first surface (11) and the second surface (12) are inclined with respect to each other.

[0082] According to this aspect, there is an advantage that the light extraction efficiency is likely to be improved as compared with the case where the first surface (11) and the second surface (12) are parallel to each other.

[0083] In the optical system (100, 100A to 100C) according to the fifth aspect, in any one of the first to fourth aspects, the light guide plate (1) further includes an indirect optical path (L2). The indirect optical path (L2) is an optical path in which the light incident from the incident surface (10) is reflected by the second surface (12), then reflected by the prism (3), and emitted from the second surface (12).

[0084] According to this aspect, there is an advantage that it is easier to control the direction of the light emitted from the second surface (12).

[0085] In the optical system (100, 100A to 100C) according to the sixth aspect, in any of the first to fifth aspects, the prisms (3) are provided so as to be arranged in a plurality in the direction in which light is incident on the incident surface (10).

[0086] According to this aspect, there is an advantage that the light extraction efficiency can be improved.

[0087] In the optical system (100A) according to the seventh aspect, in any of the first to sixth aspects, at least a part of the prism (3) is 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 arranged.

[0088] According to this aspect, there is an advantage that it is easy to control the direction of the light emitted from the second surface (12).

[0089] In the optical system (100, 100A to 100C) according to the eighth aspect, in any of the first to seventh aspects, the prism (3) has a plurality of small prisms (31) that are divided so as to be spaced apart from each other.

[0090] According to this aspect, there is an advantage that it is easier to form the prism (3) on the first surface (11) compared to the case where the prism (3) is not divided.

[0091] In the optical system (100A) according to the ninth aspect, in the eighth aspect, two or more of the plurality of small prisms (31) are arranged so as to be arranged in a curved shape when viewed from the direction in which the first surface (11) and the second surface (12) are arranged.

[0092] According to this aspect, there is an advantage that it is easy to control the direction of the light emitted from the second surface (12).

[0093] The lighting system (200) according to the 10th aspect includes the optical system (100, 100A to 100C) of any one of the 1st to 9th aspects and a light source (4). The light source (4) emits light to the incident surface (10) through the light control body (2).

[0094] According to this aspect, there is an advantage that the light extraction efficiency can be improved.

[0095] The display system (300) according to the 11th aspect includes the lighting system (200) according to the 10th aspect and a display (5). The display (5) receives the light emitted from the lighting system (200) and displays an image.

[0096] According to this aspect, there is an advantage that the light extraction efficiency can be improved.

[0097] The moving body (B1) according to the 12th aspect includes the display system (300) according to the 11th aspect and a moving body main body (B11) on which the display system (300) is mounted.

[0098] According to this aspect, there is an advantage that the light extraction efficiency can be improved.

[0099] Regarding the configurations according to the 2nd to 9th aspects, they are not essential configurations of the optical system (100) and can be omitted as appropriate.

Explanation of Reference Numerals

[0100] 1 Light guide plate 10 Incident surface 11 First surface 12 Second surface 2 Light control body 3 Prism 31 Small prism 4 Light source 5 Display 100, 100A to 100C Optical system 200 Lighting system 300 Display system B1 Automobile (mobile body) B11 Mobile body main body L1 Direct optical path L2 Indirect optical path

Claims

1. A light guide plate having an incident surface on which light is incident, and a first surface and a second surface facing each other, wherein the second surface is an emission surface of light; A light control body that condenses light directed toward the incident surface and emits the condensed light to the incident surface; A prism provided on the first surface that reflects light passing through the inside of the light guide plate toward the second surface; and The light guide plate includes a direct optical path that directly reflects light incident from the incident surface by the prism and emits the light from the second surface; The light control body is integral with the light guide plate; The light control body condenses light that directly enters the light control body from a light source disposed outside the light control body; The incident surface is a virtual plane disposed opposite to the light incident surface of the light control body and orthogonal to the second surface; The optical axis of the light control body is inclined toward the first surface with respect to the incident surface such that more light travels from the incident surface toward the first surface than from the incident surface toward the second surface in the light guide plate; The light control body is a single optical element; The light incident surface of the light control body: Is a refracting surface that controls the divergence angle of the light by refracting the light emitted by the light source; And protrusions respectively formed at an edge portion on the first surface side and an edge portion on the second surface side of the refracting surface; The protrusions protrude toward the light source side from the refracting surface; The protrusions have an inner surface and an outer surface; The outer surface is curved so as to approach the inner surface side as it approaches the light source side; The outer surface constitutes a total reflection surface that totally reflects light that has passed through the inner surface from the light source and entered the inside of the protrusion, and emits the totally reflected light to the incident surface; An optical system.

2. The light control body refracts or totally reflects light incident on the incident surface on a surface opposite to the light guide plate and emits the light to the incident surface. The optical system according to Claim 1.

3. A plurality of the prisms are provided; The depths of the plurality of prisms increase as they extend in the traveling direction of the light incident on the incident surface. The optical system according to Claim 1 or 2.

4. The direct optical path includes an optical path of light that is totally reflected by the prism. The optical system according to any one of Claims 1 to 3.

5. The first surface and the second surface are inclined with respect to each other. The optical system according to any one of Claims 1 to 4.

6. The light guide plate further includes an indirect optical path in which light incident from the incident surface is reflected by the second surface and then reflected by the prism and emitted from the second surface. The optical system according to any one of claims 1 to 5.

7. The prisms are provided so as to be arranged in a plurality in the direction in which light is incident on the incident surface. The optical system according to any one of claims 1 to 6.

8. At least a part of the prism is inclined with respect to the incident surface when viewed from the thickness direction of the light guide plate. The optical system according to any one of claims 1 to 7.

9. The prism has a plurality of small prisms divided so as to be spaced apart from each other. The optical system according to any one of claims 1 to 8.

10. Two or more of the plurality of small prisms are arranged so as to be arranged in a curved shape when viewed from the thickness direction of the light guide plate. The optical system according to claim 9.

11. The optical system according to any one of claims 1 to 10, and the light source that emits light to the incident surface through the light control body. An illumination system.

12. The illumination system according to claim 11, and a display that receives the light emitted from the illumination system and displays an image. A display system.

13. The display system according to claim 12, and a mobile body main body on which the display system is mounted. A mobile body.

Images