Optical systems and image display devices

Abstract

Provided are an optical system and an image display device that enable improved color uniformity. An optical system (3) comprises a light guide member (4) that guides image light (L1), which includes first incident light (L11) in a first wavelength band and second incident light (L21) in a second wavelength band with a wavelength shorter than the first wavelength band, to a visual field region (8) as a virtual image. The light guide member (4) has a first split region (52) having a plurality of first split points that split the incident first light (L11) and a second split region (62) having a plurality of second split points that split the incident second light (L21). The plurality of first split points include first and second points (first split points (P11, P14)) corresponding respectively to first and second peripheral regions (81, 82) of the visual field region (8). The plurality of second split points include third and fourth points (second split points (Q11, Q14)) respectively corresponding to first and second peripheral regions (81, 82). The split efficiencies E1 to E4 at the first to fourth points satisfy the following equation (1).

Description

Technical Field

[0004]

[0001] The present disclosure relates to an optical system and an image display device.

Background Art

[0002] Patent Document 1 discloses an exit pupil expander. The exit pupil expander disclosed in Patent Document 1 uses a substrate provided with three layers of optical members. Each of the first to third layers has an incident diffraction grating and an exit diffraction grating. In Patent Document 1, in order to make the relative amounts of different color components of the exit light approach the relative amounts of different color components of the incident light, the diffraction gratings of each of the first to third layers have different diffraction periods. The diffraction period of the first layer is determined based on the wavelength of the red component. The diffraction period of the second layer is determined based on the wavelength of the green component. The diffraction period of the third layer is determined based on the wavelength of the blue component. [[ID=!]]

Prior Art Documents

Patent Documents

[0003] <00000!7>

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, incident light has red, green, and blue components. Here, light with a shorter wavelength is more likely to be absorbed inside the optical member. This tendency becomes more prominent as the refractive index of the optical member increases. In Patent Document 1, the more the blue component propagates inside the optical member, the more it is absorbed inside the optical member than the red and green components, and as a result, on the substrate, there may be a difference in color between a portion close to the incident diffraction grating and a portion far from the incident diffraction grating in the exit diffraction grating.

[0005] !> The present disclosure provides an optical system and an image display device that enable improvement in color uniformity.

Means for Solving the Problems

[0006] An optical system according to one aspect of the present disclosure includes a light guide member that guides image light, which forms an image output from a display element, as a virtual image into the user's field of view. The image light includes first light in a first wavelength band and second light in a second wavelength band with a shorter wavelength than the first wavelength band. The light guide member has a first coupling region, a first dividing region, a second coupling region, and a second dividing region. The first coupling region causes the first light to be incident into the light guide member so that the first light propagates within the light guide member. The first dividing region has a plurality of first dividing points that divide the first light incident into the light guide member from the first coupling region, and emits a plurality of first emitted light into the field of view. The second coupling region causes the second light to be incident into the light guide member so that the second light propagates within the light guide member. The second dividing region has a plurality of second dividing points that divide the second light incident into the light guide member from the second coupling region, and emits a plurality of second emitted light into the field of view. The field of view region has a first peripheral region at the first end in a predetermined direction within the plane of the field of view region, and a second peripheral region at the second end in the predetermined direction. The plurality of first division points include a first point and a second point aligned in the first propagation direction to divide the first light propagating in the first propagation direction corresponding to the predetermined direction. The first point corresponds to a point in the first peripheral region, and the second point corresponds to a point in the second peripheral region that is further from the first bonding region than the first point. The plurality of second division points include a third point and a fourth point aligned in the second propagation direction to divide the second light propagating in the second propagation direction corresponding to the predetermined direction. The third point corresponds to a point in the first peripheral region, and the fourth point corresponds to a point in the second peripheral region that is further from the second bonding region than the third point. If E1 is the splitting efficiency for the first light at the first point, E2 is the splitting efficiency for the first light at the second point, E3 is the splitting efficiency for the second light at the third point, and E4 is the splitting efficiency for the second light at the fourth point, then the splitting efficiencies E1, E2, E3, and E4 satisfy the following equation (1).

number

[0007] An image display device according to one aspect of this disclosure comprises the optical system described above and a display element. [Effects of the Invention]

[0008] Aspects of this disclosure enable improved color uniformity. [Brief explanation of the drawing]

[0009] [Figure 1] Schematic perspective view of the image display device of Embodiment 1 [Figure 2] Diagram illustrating the field of view [Figure 3] Front view of the first substrate of the light guide member of the image display device shown in Figure 1. [Figure 4] Front view of the second substrate of the light guide member of the image display device shown in Figure 1. [Figure 5] Graph of the division efficiency of the light guide member of the image display device of Embodiment 1 in Embodiment 1. [Figure 6] Graph of extracted light intensity for the comparative example. [Figure 7] Graph showing the ratio of the light intensity of the second light source to the first light source in the comparative example. [Figure 8] Graph of the division efficiency of the light guide member of the image display device of Embodiment 1 in Embodiment 2. [Figure 9] Graph of the division efficiency of the light guide member of the image display device of Embodiment 1 in Embodiment 3. [Figure 10] Graph of the division efficiency of the light guide member of the image display device of Embodiment 1 in Embodiment 4. [Figure 11] Graph of the division efficiency of the light guide member of the image display device of Embodiment 1 in Embodiment 5. [Figure 12] Graph of the division efficiency of the light guide member of the image display device of Embodiment 1 in Embodiment 6. [Figure 13] Graph of the division efficiency of the light guide member of the image display device of Embodiment 1 in Embodiment 7. [Figure 14] Graph of the division efficiency of the light guide member of the image display device of Embodiment 1 in Embodiment 8. [Figure 15] Graph of the division efficiency of the light guide member of the image display device of Embodiment 1 in Embodiment 9. [Figure 16] Schematic perspective view of the image display device of Embodiment 2 [Figure 17] Front view of the light guide member of the image display device shown in Figure 16. [Figure 18] Rear view of the light guide member of the image display device of FIG. 16

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, detailed descriptions that are more than necessary may be omitted. For example, detailed descriptions of well-known matters and duplicate descriptions of substantially the same configurations may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate the understanding of those skilled in the art. Note that the inventors provide the accompanying drawings and the following description so that those skilled in the art can fully understand the present disclosure, and do not intend to limit the subject matter described in the claims by these.

[0011] Unless otherwise specified, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Each of the drawings described in the following embodiments is a schematic diagram, and the ratios of the sizes and thicknesses of each component in each drawing do not necessarily reflect the actual dimensional ratios. Also, the dimensional ratios of each element are not limited to the ratios shown in the drawings.

[0012] In the present disclosure, expressions such as "directing light in the XX direction" and "propagating light in the XX direction" with respect to light mean that the light forming an image as a whole travels in the XX direction, and the light rays included in the light forming the image may be inclined with respect to the XX direction. For example, "light traveling in the XX direction" only requires that the principal ray of this light is directed in the XX direction, and the secondary rays of the light may be inclined with respect to the XX direction.

[0013] [1. Embodiments] [1.1 Embodiment 1] [1.1.1 Configuration] FIG. 1 is a schematic diagram of a configuration example of an image display device 1. The image display device 1 is, for example, a head-mounted display (HMD) that is worn on a user's head and displays an image (video). As shown in FIG. 1, the image display device 1 includes a display element 2 and an optical system 3.

[0014] The display element 2 outputs image light L1 to form an image (video) in order to display an image (video). Here, for simplicity, Figure 1 depicts the image light L1 as directional light, but in reality, it is incident on the optical system 3 as light with an angle corresponding to the field of view. The image light L1 includes light output from each point of the display element 2. In this embodiment, the image light L1 includes a first light L11 in a first wavelength band and a second light L21 in a second wavelength band with a shorter wavelength than the first wavelength band. That is, the upper limit of the second wavelength band is smaller than the lower limit of the first wavelength band. The first wavelength band is, for example, 510 nm to 780 nm. The first light L11 includes, for example, red light and green light. The first light L11 has, for example, a peak in the range of 495 nm to 570 nm and a peak in the range of 620 nm to 750 nm. The first light L11 may be red light or green light. The second wavelength band is, for example, 380 nm to 480 nm. The second light L21 is blue light. The second light L21 has a peak in the range of 450 nm to 495 nm. Each point of the display element 2 corresponds to, for example, each pixel (red, green, and blue pixels) of the display element 2. The optical axis of the display element 2 is the optical axis of the image light L1. The optical axis of the image light L1 is, for example, the optical axis of the light output from the center of the display element 2. Examples of the display element 2 include known displays such as liquid crystal displays, organic EL displays, and scanning MEMS mirrors.

[0015] The optical system 3 directs the image light L1 output by the display element 2 to a field of view 8 set for the user's eye. In the field of view 8, the user can view the image formed by the display element 2 with their own eyes without interruption. In particular, in this embodiment, the optical system 3 widens the field of view 8 by the action of pupil dilation. That is, the optical system 3 widens the field of view 8 by duplicating the pupil of the image light L1.

[0016] Figure 2 is an explanatory diagram of the field of view 8. The field of view 8 is defined by a rectangular plane. The field of view 8 includes a plurality of points R21-R24, R31-R34, R41-R44 (hereinafter collectively denoted by the symbol R). The plurality of points R correspond to the pupil positions of the image light L1 replicated by the optical system 3. The field of view 8 has a first peripheral region 81 on the first end 8a side in a predetermined direction A1 within the plane of the field of view 8, and a second peripheral region 82 on the second end 8b side in the predetermined direction A1. Furthermore, within the plane of the field of view 8, the field of view 8 has a third peripheral region 83 on the third end 8c side in a second predetermined direction A2 that intersects with the first predetermined direction A1, and a fourth peripheral region 84 on the fourth end 8d side in the second predetermined direction A2. For example, the first predetermined direction A1 corresponds to the horizontal direction, and the second predetermined direction A2 corresponds to the vertical direction. The first peripheral region 81 is a rectangular region extending from the first end 8a of the field of view region 8 toward the center.

[0017] The dimensions of the first peripheral region 81 in the first predetermined direction A1 are 25% of the dimensions of the field of view region 8 in the first predetermined direction A1. The dimensions of the first peripheral region 81 in the second predetermined direction A2 are equal to the dimensions of the field of view region 8 in the second predetermined direction A2. Therefore, the first peripheral region 81 occupies 1 / 4 of the field of view region 8 from its first edge 8a in the first predetermined direction A1.

[0018] The second peripheral region 82 is a rectangular region extending from the second end 8b of the field of view 8 toward the center. The dimensions of the second peripheral region 82 in the first predetermined direction A1 are 25% of the dimensions of the field of view 8 in the first predetermined direction A1. The dimensions of the second peripheral region 82 in the second predetermined direction A2 are equal to the dimensions of the field of view 8 in the second predetermined direction A2. Therefore, the second peripheral region 82 occupies 1 / 4 of the field of view 8 from the second end 8b in the first predetermined direction A1.

[0019] The third peripheral region 83 is a rectangular region extending from the third end 8c of the field of view 8 toward the center. The dimensions of the third peripheral region 83 in the second predetermined direction A2 are 25% of the dimensions of the field of view 8 in the second predetermined direction A2. The dimensions of the third peripheral region 83 in the first predetermined direction A1 are equal to the dimensions of the field of view 8 in the first predetermined direction A1. Therefore, the third peripheral region 83 occupies 1 / 4 of the field of view 8 in the second predetermined direction A2 from the third end 8c of the field of view 8.

[0020] The fourth peripheral region 84 is a rectangular region extending from the fourth edge 8d of the field of view 8 toward the center. The dimensions of the fourth peripheral region 84 in the second predetermined direction A2 are 25% of the dimensions of the field of view 8 in the second predetermined direction A2. The dimensions of the fourth peripheral region 84 in the first predetermined direction A1 are equal to the dimensions of the field of view 8 in the first predetermined direction A1. Therefore, the fourth peripheral region 84 occupies 1 / 4 of the field of view 8 from the fourth edge 8d in the second predetermined direction A2.

[0021] As shown in Figure 1, the optical system 3 comprises a light guide member 4 and a projection optical system 7.

[0022] The light guide member 4 guides the image light L1, which forms the image output from the display element 2, into the user's field of view area 8 as a virtual image. The light guide member 4 in Figure 1 comprises a first substrate 5 and a second substrate 6. Since the first substrate 5 and the second substrate 6 constitute the light guide member 4, the propagation of light within the first substrate 5 or the second substrate 6 may be referred to as the propagation of light within the light guide member 4.

[0023] Figure 3 is a front view of the first substrate 5 as seen from the display element 2 side. The first substrate 5 comprises a main body portion 50, a first coupling region 51, and a first dividing region 52.

[0024] The main body 50 is made of a material that is transparent in the visible light region and has a first surface 50a and a second surface 50b in the thickness direction. The refractive index of the main body 50 with respect to the d line (wavelength 587.562 nm) is greater than 1.7. The internal absorption rate of the main body 50 with respect to the first light L11 is substantially 0. In this embodiment, the main body 50 is in the shape of a rectangular plate. As shown in Figure 1, the main body 50 is positioned with the first surface 50a facing the display element 2 side and the second surface 50b facing the viewing area 8 side (second substrate 6 side).

[0025] The first coupling region 51 causes the first light L11 to be incident into the light guide member 4 so that the first light L11 propagates within the light guide member 4. In this embodiment, the first coupling region 51 causes the first light L11 to be incident into the first substrate 5 (main body portion 50) of the light guide member 4 so that the first light L11 propagates in a first direction D1 (left direction in Figure 3) perpendicular to the thickness direction of the first substrate 5 (thickness direction of the main body portion 50). In this embodiment, the image light L1 includes the first light L11 and the second light L21. The first coupling region 51 is set to act more on the first light L11 than on the second light L21, causing the first light L11 of the image light L1 to be incident into the first substrate 5 and the second light L21 of the image light L1 to pass through the first substrate 5. However, a portion of the second light L21 may inevitably be incident into the first substrate 5. The first coupling region 51 is used for coupling the display element 2 and the light guide member 4. The first coupling region 51 causes the first light L11 of the image light L1 to be incident into the first substrate 5 so as to propagate through the first substrate 5 under total internal reflection conditions. Here, "coupling" refers to the state in which light propagates through the light guide member 4 under total internal reflection conditions. In this embodiment, the first direction D1 corresponds to the first predetermined direction of the field of view region 8.

[0026] The first bonding region 51 is composed of a periodic structure having a diffracting effect on the first light L11. The periodic structure of the first bonding region 51 is, for example, a transmission type diffraction grating. The first bonding region 51 is formed, for example, on the first surface 50a of the main body 50. The diffraction grating of the first bonding region 51 may include, for example, a plurality of recesses or protrusions that extend in a second direction D2 (downward in Figure 3) which is perpendicular to the thickness direction of the main body 50 of the first substrate 5 and intersects the first direction D1, and are arranged at predetermined intervals in the first direction D1. In this embodiment, the second direction D2 is also perpendicular to the first direction D1. The first bonding region 51 causes the first light L11 to be incident into the main body 50 under conditions of total internal reflection with respect to the first surface 50a and the second surface 50b by the diffracting effect. Due to the first coupling region 51, the first light L11 travels in the first direction D1 by undergoing total internal reflection within the first substrate 5 (i.e., within the main body 50) by the first surface 50a and the second surface 50b.

[0027] The size of the first coupling region 51 is set so that part or all of the first light L11 of the image light L1 from the display element 2 that has passed through the projection optical system 7 is incident on the first coupling region 51. In this embodiment, as shown in Figure 3, the first coupling region 51 is circular in shape.

[0028] The first divided region 52 divides the first light L11 that has entered the light guide member 4 from the first combined region 51 into a plurality of first emitted light L13 and emits them into the field of view region 8, thereby replicating and expanding the pupil of the first light L11 of the image light L1. In this embodiment, the plurality of first emitted light L13 are parallel to each other. "The plurality of first emitted light L13 are parallel to each other" does not mean that the plurality of first emitted light L13 are parallel to each other in a strict sense, but also includes the plurality of first emitted light L13 being approximately parallel to each other. Even if the plurality of first emitted light L13 are not parallel to each other in a strict sense, it is sufficient if the orientation of the plurality of first emitted light L13 is aligned to the extent that the plurality of first emitted light L13 are considered to be parallel in terms of optical design. Since the multiple first emitted light rays L13 are parallel to each other, the uniformity of the pupil arrangement of the image light L1 in the field of view 8 can be improved, thereby reducing the gap in the pupil of the image light L1 in the field of view 8.

[0029] The first divided region 52 in Figure 3 has multiple first division points P11-P14, P21-P24, P31-P34, and P41-P44 (hereinafter collectively denoted by the symbol P), and emits multiple parallel first emitted light rays L13 to the field of view region 8. The number of first division points P corresponds to the number of divisions of the first light ray L11. The distance between the first division points P depends on the refractive index of the first substrate 5. The larger the refractive index of the first substrate 5, the smaller the distance between the first division points P. Therefore, by increasing the refractive index of the first substrate 5, the distance between the first division points P can be reduced, thereby reducing the pupil break of the image light L1 in the field of view region 8.

[0030] The first divided region 52 in Figure 3 includes the first extended region 521 and the first ejection region 522.

[0031] The first extended region 521 is positioned in the first direction D1 so as to be aligned with the first bonding region 51. The first extended region 521 divides the first light L11 propagating within the light guide member 4, directing a plurality of first light L12 aligned in the first direction D1 toward the first emission region 522. In this embodiment, the first extended region 521 has first division points P11 to P14 among a plurality of first division points P11 to P14, P21 to P24, P31 to P34, and P41 to P44. The first division points P11 to P14 are aligned in the first direction D1. The first extended region 521 propagates the first light L11 from the first bonding region 51 along the first direction D1, and directs a portion of the first light L11 at each of the first division points P11 to P14 toward the second direction D2 as first light L12. In this way, the first expansion region 521 expands the pupil of the first light L11 in the first direction D1. That is, as shown in Figure 3, the first expansion region 521 duplicates and expands the pupil of the first light L11 of the image light L1 projected by the projection optical system 7 in the first direction D1 by dividing the first light L11 into a plurality of parallel first light L12 toward the first emission region 522.

[0032] The first extended region 521 is composed of a periodic structure having a diffraction effect on the first light L11. The periodic structure of the first extended region 521 is, for example, a reflective diffraction grating. The first extended region 521 is formed, for example, on the first surface 50a of the main body 50. The diffraction grating of the first extended region 521 may include, for example, a plurality of recesses or protrusions that extend along a direction inclined at 45 degrees with respect to the first direction D1 in a plane perpendicular to the thickness direction of the main body 50 and are arranged at predetermined intervals in a direction inclined at 135 degrees with respect to the first direction D1.

[0033] The size of the first extended region 521 is set so that all of the first light L11 from the first combined region 51 is incident on the first extended region 521. In this embodiment, as shown in Figure 3, the first extended region 521 is rectangular in shape. The length of the first extended region 521 in the first direction D1 is, for example, 100 mm or more.

[0034] The first emission region 522 is positioned in the second direction D2 so as to be aligned with the first extended region 521. The first emission region 522 emits multiple first beams L13 aligned in the second direction D2 as multiple first emission beams L13 to the field of view region 8 by dividing multiple first beams L12 from the first extended region 521. In this embodiment, the first emission region 522 has first division points P21~P24, P31~P34, and P41~P44 from among multiple first division points P11~P14, P21~P24, P31~P34, and P41~P44. The first division points P21, P31, and P41 are aligned in the second direction D2. The first division points P22, P32, and P42 are aligned in the second direction D2. The first division points P23, P33, and P43 are aligned in the second direction D2.

[0035] The first emission region 522 propagates the first light L12 from the first division point P11 of the first extended region 521 in the second direction D2, and at each of the first division points P21, P31, and P41, a portion of the first light L12 is emitted from the light guide member 4 as the first emitted light L13 to the field of view region 8. The first emission region 522 propagates the first light L12 from the first division point P12 of the first extended region 521 in the second direction D2, and at each of the first division points P22, P32, and P42, a portion of the first light L12 is emitted from the light guide member 4 as the first emitted light L13 to the field of view region 8. The first emission region 522 propagates the first light L12 from the first division point P13 of the first extended region 521 in the second direction D2, and at each of the first division points P23, P33, and P43, a portion of the first light L12 is emitted from the light guide member 4 as the first emitted light L13 to the field of view region 8.

[0036] In this way, the first emission region 522 expands the pupil of the first light L11 in the second direction D2. That is, as shown in Figure 1, the first emission region 522 duplicates and expands the pupil of the first light L11 projected by the projection optical system 7 in the second direction D2 by dividing the first light L11 into a plurality of parallel first emission lights L13 directed from the light guide member 4 toward the field of view region 8. The light divided at the first division points P21~P24, P31~P34, and P41~P44 of the first emission region 522 reaches a plurality of points R21~R24, R31~R34, and R41~R44 in the field of view region 8, respectively. Therefore, the first division points P21~P24, P31~P34, and P41~P44 correspond to a plurality of points R21~R24, R31~R34, and R41~R44 in the field of view region 8, respectively.

[0037] The first emission region 522 is composed of a periodic structure having a diffracting effect on the first light L11. The periodic structure of the first emission region 522 is, for example, a reflective diffraction grating. The first emission region 522 is formed, for example, on the first surface 50a of the main body 50. The diffraction grating of the first emission region 522 may include, for example, a plurality of recesses or protrusions extending in a first direction D1 and arranged at predetermined intervals in a second direction D2.

[0038] The size of the first emission region 522 is set so that all of the first light L12 from the first extended region 521 enters the first emission region 522. In this embodiment, as shown in Figure 3, the first emission region 522 is rectangular in shape. The length of the first emission region 522 in the first direction D1 is, for example, 100 mm or more. The length of the first emission region 522 in the second direction D2 is, for example, 100 mm or more.

[0039] Figure 4 is a front view of the second substrate 6 as seen from the display element 2 side. The second substrate 6 comprises a main body portion 60, a second coupling region 61, and a second dividing region 62.

[0040] The main body 60 is made of a material that is transparent in the visible light region and has a first surface 60a and a second surface 60b in the thickness direction. The refractive index of the main body 60 with respect to the d line (wavelength 587.562 nm) is greater than 1.7. The internal absorption rate of the main body 60 with respect to the second light L21 is greater than 0.05% / mm and less than 0.50% / mm. In this embodiment, the main body 60 is in the shape of a rectangular plate. As shown in Figure 1, the main body 60 is positioned with the first surface 60a facing the display element 2 side (first substrate 5 side) and the second surface 60b facing the viewing area 8 side.

[0041] The second coupling region 61 causes the second light L21 to be incident into the light guide member 4 so that the second light L21 propagates within the light guide member 4. In this embodiment, the second coupling region 61 causes the second light L21 to be incident into the second substrate 6 (main body portion 60) of the light guide member 4 so that the second light L21 propagates in a third direction D3 (left direction in Figure 4) perpendicular to the thickness direction of the second substrate 6 (thickness direction of the main body portion 60). The second coupling region 61 is used for coupling the display element 2 and the light guide member 4. The second coupling region 61 causes the second light L21 of the image light L1 to be incident into the second substrate 6 so that it propagates within the second substrate 6 under total internal reflection conditions. In this embodiment, the third direction D3 corresponds to the first predetermined direction A1 of the field of view 8. Therefore, the third direction D3 of the second substrate 6 corresponds to the first direction D1 of the first substrate 5.

[0042] The second bonding region 61 is composed of a periodic structure having a diffracting effect on the second light L21. The periodic structure of the second bonding region 61 is, for example, a transmission-type diffraction grating. The second bonding region 61 is formed, for example, on the first surface 60a of the main body 60. The diffraction grating of the second bonding region 61 may include, for example, a plurality of recesses or protrusions that extend in a fourth direction D4 (downward in Figure 4) which is perpendicular to the thickness direction of the main body 60 of the second substrate 6 and intersects the third direction D3, and are arranged at predetermined intervals in the third direction D3. In this embodiment, the fourth direction D4 is also perpendicular to the third direction D3. The fourth direction D4 corresponds to the second predetermined direction A2 of the field of view 8. Therefore, the fourth direction D4 of the second substrate 6 corresponds to the second direction D2 of the first substrate 5. The second bonding region 61 causes the second light L21 to be incident into the main body 60 under conditions of total internal reflection with respect to the first surface 60a and the second surface 60b by the diffracting effect. Due to the second coupling region 61, the second light L21 is totally reflected within the second substrate 6 (i.e., within the main body 60) by the first surface 60a and the second surface 60b, and travels in the third direction D3.

[0043] The size of the second coupling region 61 is set so that part or all of the second light L21 of the image light L1 from the display element 2 that has passed through the projection optical system 7 enters the second coupling region 61. In this embodiment, as shown in Figure 4, the second coupling region 61 is circular in shape.

[0044] The second division region 62 divides the second light L2 that has entered the light guide member 4 from the second coupling region 61 into a plurality of second emitted light L23 and emits them into the field of view region 8, thereby replicating and expanding the pupil of the second light L21 of the image light L1. In this embodiment, the plurality of second emitted light L23 are parallel to each other. "The plurality of second emitted light L23 are parallel to each other" does not mean that they are parallel to each other in a strict sense, but also that they are approximately parallel to each other. In other words, even if the plurality of second emitted light L23 are not parallel to each other in a strict sense, it is sufficient if the orientation of the plurality of second emitted light L23 is aligned to the extent that they can be considered parallel from an optical design perspective. The parallelism of the plurality of second emitted light L23 improves the uniformity of the arrangement of the pupil of the image light L1 in the field of view region 8, thereby reducing the gap in the pupil of the image light L1 in the field of view region 8.

[0045] The second division region 62 in Figure 4 has multiple second division points Q11-Q14, Q21-Q24, Q31-Q34, Q41-Q44 (hereinafter collectively denoted by the symbol Q), and emits multiple parallel second emitted light beams L23 to the field of view region 8. The number of second division points Q corresponds to the number of divisions of the second light beam L21. The distance between the second division points Q depends on the refractive index of the second substrate 6. The larger the refractive index of the second substrate 6, the smaller the distance between the second division points Q. Therefore, increasing the refractive index of the second substrate 6 reduces the distance between the second division points Q, thereby reducing the pupil breakout of the image light L1 in the field of view region 8.

[0046] The second divided region 62 in Figure 4 includes the second extended region 621 and the second ejection region 622.

[0047] The second extended region 621 is positioned in the third direction D3 so as to be aligned with the second bonding region 61. The second extended region 621 divides the second light L21 propagating within the light guide member 4, directing a plurality of second light L22 aligned in the third direction D3 toward the second emission region 622. In this embodiment, the second extended region 621 has second division points Q11 to Q14, among a plurality of second division points Q11 to Q14, Q21 to Q24, Q31 to Q34, and Q41 to Q44. The second division points Q11 to Q14 are aligned in the third direction D3. The second extended region 621 propagates the second light L21 from the second bonding region 61 along the third direction D3, directing a portion of the second light L21 at each of the second division points Q11 to Q14 toward the fourth direction D4 as second light L22. In this way, the second extended region 621 expands the pupil of the second light L21 in the third direction D3. That is, as shown in Figure 4, the second extended region 621 duplicates and expands the pupil of the second light L21 of the image light L1 projected by the projection optical system 7 in the third direction D3 by dividing the second light L21 into a plurality of parallel second light L22s toward the second output region 622.

[0048] The second extended region 621 is composed of a periodic structure having a diffraction effect on the second light L21. The periodic structure of the second extended region 621 is, for example, a reflective diffraction grating. The second extended region 621 is formed, for example, on the first surface 60a of the main body 60. The diffraction grating of the second extended region 621 may include, for example, a plurality of recesses or protrusions that extend along a direction inclined at 45 degrees with respect to the third direction D3 in a plane perpendicular to the thickness direction of the main body 60 and are arranged at predetermined intervals in a direction inclined at 135 degrees with respect to the third direction D3.

[0049] The size of the second extended region 621 is set so that all of the second light L21 from the second combined region 61 is incident on the second extended region 621. In this embodiment, as shown in Figure 4, the second extended region 621 is rectangular in shape. The length of the second extended region 621 in the third direction D3 is, for example, 100 mm or more.

[0050] The second emission region 622 is positioned in the fourth direction D4 so as to be aligned with the second extended region 621. The second emission region 622 emits multiple second beams L23 aligned in the fourth direction D4 as multiple second emission beams L23 to the field of view region 8 by dividing multiple second beams L22 from the second extended region 621. In this embodiment, the second emission region 622 has second division points Q21~Q24, Q31~Q34, and Q41~Q44, among multiple second division points Q11~Q14, Q21~Q24, Q31~Q34, and Q41~Q44. Second division points Q21, Q31, and Q41 are aligned in the fourth direction D4. Second division points Q22, Q32, and Q42 are aligned in the fourth direction D4. Second division points Q23, Q33, and Q43 are aligned in the fourth direction D4.

[0051] The second emission region 622 propagates the second light L22 from the second division point Q11 of the second extended region 621 in the fourth direction D4, and at each of the second division points Q21, Q31, and Q41, a portion of the second light L22 is emitted from the light guide member 4 as the second emitted light L23 to the field of view region 8. The second emission region 622 propagates the second light L22 from the second division point Q12 of the second extended region 621 in the fourth direction D4, and at each of the second division points Q22, Q32, and Q42, a portion of the second light L22 is emitted from the light guide member 4 as the second emitted light L23 to the field of view region 8. The second emission region 622 propagates the second light L22 from the second division point Q13 of the second extended region 621 in the fourth direction D4, and at each of the second division points Q23, Q33, and Q43, a portion of the second light L22 is emitted from the light guide member 4 as the second emitted light L23 to the field of view region 8.

[0052] In this way, the second emission region 622 expands the pupil of the second light L21 in the fourth direction D4. That is, as shown in Figure 1, the second emission region 622 duplicates and expands the pupil of the second light L21 projected by the projection optical system 7 in the fourth direction D4 by dividing the second light L21 into a plurality of parallel second emission beams L23 directed from the light guide member 4 toward the field of view region 8. The light divided at the second division points Q21~Q24, Q31~Q34, and Q41~Q44 of the second emission region 622 reaches a plurality of points R21~R24, R31~R34, and R41~R44 in the field of view region 8, respectively. Therefore, the second division points Q21~Q24, Q31~Q34, and Q41~Q44 correspond to a plurality of points R21~R24, R31~R34, and R41~R44 in the field of view region 8, respectively. Multiple second division points Q11~Q14, Q21~Q24, Q31~Q34, Q41~Q44 and multiple first division points P11~P14, P21~P24, P31~P34, P41~P44 correspond to the same points R21~R24, R31~R34, R41~R44 in field of view 8.

[0053] The second emission region 622 is composed of a periodic structure having a diffraction effect on the second light L21. The periodic structure of the second emission region 622 is, for example, a reflective diffraction grating. The second emission region 622 is formed, for example, on the first surface 60a of the main body 60. The diffraction grating of the second emission region 622 may include, for example, a plurality of recesses or protrusions extending in the third direction D3 and arranged at predetermined intervals in the fourth direction D4.

[0054] The size of the second emission region 622 is set so that all of the second light L22 from the second extended region 621 is incident on the second emission region 622. In this embodiment, as shown in Figure 4, the second emission region 622 is rectangular in shape. The length of the second emission region 622 in the third direction D3 is, for example, 100 mm or more. The length of the second emission region 622 in the fourth direction D4 is, for example, 100 mm or more.

[0055] In the light guide member 4 shown in Figure 1, the first substrate 5 and the second substrate 6 face each other with an air layer 41 in between. More specifically, the first substrate 5 and the second substrate 6 are arranged such that the thickness direction of the main body portion 50 of the first substrate 5 coincides with the thickness direction of the main body portion 60 of the second substrate 6, and the second surface 50b of the main body portion 50 and the first surface 60a of the main body portion 60 face each other with the air layer 41 in between. The direction that coincides with the thickness direction of the main body portion 50 of the first substrate 5 and the thickness direction of the main body portion 60 of the second substrate 6 is the thickness direction of the light guide member 4. Viewed from the thickness direction of the light guide member 4, the first bonding region 51 and the first dividing region 52 (first extended region 521 and first emission region 522) of the first substrate 5 overlap with the second bonding region 61 and the second dividing region 62 (second extended region 621 and second emission region 622) of the second substrate 6.

[0056] Image light L1 from the display element 2 is incident on the first coupling region 51 of the first substrate 5 of the light guide member 4, and the first coupling region 51 directs the first light L11 of the image light L1 towards the first dividing region 52. In the first dividing region 52, the first extended region 521 divides the first light L11 from the first coupling region 51 into multiple first light L12 at multiple first division points P11 to P14 and directs them towards the first emission region 522. The first emission region 522 divides the multiple first light L12 at multiple first division points P21 to P24, P31 to P34, and P41 to P44 and emits multiple first emitted light L13 into the field of view region 8. The image light L1 that has passed through the first coupling region 51 is incident on the second coupling region 61 of the second substrate 6. The second combining region 61 directs the second light L21 of the image light L1 towards the second dividing region 62. In the second dividing region 62, the second extended region 621 divides the second light L21 from the second combining region 61 into multiple second light L22 at multiple second division points Q11 to Q14 and directs them towards the second emission region 622. The second emission region 622 divides the multiple second light L22 at multiple second division points Q21 to Q24, Q31 to Q34, and Q41 to Q44, and emits multiple second emission light L23 into the field of view region 8.

[0057] In the light guide member 4, the first emitted light L13 from the first division points P21~P24, P31~P34, and P41~P44 of the first emission region 522 reaches multiple points R21~R24, R31~R34, and R41~R44 in the field of view region 8, respectively. The second emitted light L23 from the second division points Q21~Q24, Q31~Q34, and Q41~Q44 of the second emission region 622 reaches multiple points R21~R24, R31~R34, and R41~R44 in the field of view region 8, respectively. Therefore, a virtual image is formed at multiple points R21~R24, R31~R34, and R41~R44 in the field of view region 8 by the first emitted light L13 and the second emitted light L23.

[0058] In the light guide member 4, the first division point P11 (first point) and the second division point Q11 (third point) correspond to the same points R21, R31, and R41 in the first peripheral region 81 of the field of view 8. The first division point P14 (second point) and the second division point Q14 (fourth point) correspond to the same points R24, R34, and R44 in the second peripheral region 82 of the field of view 8. The first division point P21 (fifth point) and the second division point Q21 (seventh point) correspond to the same point R21 in the third peripheral region 83 of the field of view 8. The first division point P41 (sixth point) and the second division point Q41 (eighth point) correspond to the same point R41 in the fourth peripheral region 84 of the field of view 8. The first division point P22 (fifth point) and the second division point Q22 (seventh point) correspond to the same point R22 in the third peripheral region 83 of the field of view 8. The first division point P42 (6th point) and the second division point Q42 (8th point) correspond to the same point R42 in the 4th peripheral region 84 of the field of view 8. The first division point P23 (5th point) and the second division point Q23 (7th point) correspond to the same point R23 in the 3rd peripheral region 83 of the field of view 8. The first division point P43 (6th point) and the first division point Q43 (8th point) correspond to the same point R43 in the 4th peripheral region 84 of the field of view 8. The first division point P24 (5th point) and the second division point Q24 (7th point) correspond to the same point R24 in the 3rd peripheral region 83 of the field of view 8. The first division point P44 (6th point) and the second division point Q44 (8th point) correspond to the same point R44 in the 4th peripheral region 84 of the field of view 8.

[0059] The more equal the ratio of the light intensity of the first emitted light L13 to the light intensity of the second emitted light L23 at multiple points R21-R24, R31-R34, and R41-R44 in the field of view 8, the higher the color uniformity. Conversely, the more varied the ratio of the light intensity of the first emitted light L13 to the light intensity of the second emitted light L23 at multiple points R21-R24, R31-R34, and R41-R44 in the field of view 8, the lower the color uniformity. In other words, the more varied the ratio of the light intensity of the second emitted light L21 to the light intensity of the first emitted light L11 in the image light L1 at multiple points in the field of view 8, the lower the color uniformity. The degree of color uniformity can be evaluated, for example, by the standard deviation of the ratio of the light intensity of the second emitted light L21 to the light intensity of the first emitted light L11 in the image light L1 at multiple points in the field of view 8. In this embodiment, the second wavelength band of the second light L21, which is the source of the second emitted light L23, is shorter than the first wavelength band of the first light L11, which is the source of the first emitted light L13. Light with shorter wavelengths is more easily absorbed inside the light guide member 4. This tendency becomes more pronounced as the refractive index of the material of the light guide member 4 increases. Therefore, the amount of light from the second emitted light L23 tends to decrease further at the second division point, which is farther from the second bonding region 61. As a result, the color tint from the first emitted light L13 may become stronger at the point corresponding to the second division point, which is farther from the second bonding region 61.

[0060] In this embodiment, considering color uniformity, the light guide member 4 is configured such that the first division region 52 has different division efficiencies depending on the position of the first division point P, and the second division region 62 has different division efficiencies depending on the position of the second division point Q. The division efficiency at the first division point P is defined as the ratio of the amount of light extracted at the first division point P to the amount of light of the first light incident on the first division point P. The division efficiency at the second division point Q is defined as the ratio of the amount of light extracted at the second division point Q to the amount of light of the first light incident on the second division point Q. In the first division region 52, the division efficiency at the first division point P is determined by the shape of the periodic structure in the region corresponding to the first division point P. Factors determining the shape of the periodic structure include the aspect ratio, height, and inclination of the diffraction grating. The shape of the periodic structure should be set so that the desired division efficiency is obtained at each division point P. The same applies to the division efficiency at the second division point Q in the second division region 62.

[0061] Therefore, the uniformity of color in the first predetermined direction A1 of the field of view 8 was evaluated by varying the dispersion efficiency at the first division point P of the first extended region 521 and the dispersion efficiency at the second division point Q of the second extended region 621. As a result, it was confirmed that the variation in the uniformity of color in the first predetermined direction A1 of the field of view 8 can be reduced when the first extended region 521 and the second extended region 621 satisfy the following equation (2). Accordingly, in this embodiment, the first extended region 521 and the second extended region 621 are configured to satisfy the following equation (2).

[0062]

number

[0063] The division efficiency E1 is the division efficiency for the first light L11 at the first point. The division efficiency E2 is the division efficiency for the first light L11 at the second point. The first and second points are selected from among a plurality of first division points P11 to P14 that are aligned in the first propagation direction to divide the first light L11 propagating in the first propagation direction corresponding to the first predetermined direction A1. The first propagation direction coincides with the first direction D1. The first point corresponds to the first peripheral region 81, and the second point is further from the first coupling region 51 than the first point and corresponds to the second peripheral region 82. In this embodiment, the first division point P11 corresponds to the first point, and the first division point P14 corresponds to the second point.

[0064] The division efficiency E3 is the division efficiency for the second light L21 at the third point. The division efficiency E4 is the division efficiency for the second light L21 at the fourth point. The third and fourth points are selected from among a plurality of second division points Q11 to Q14, which are aligned in the second propagation direction to divide the second light L21 propagating in the second propagation direction corresponding to the first predetermined direction A1. The second propagation direction coincides with the third direction D3. The third point corresponds to the first peripheral region 81, and the fourth point is further from the second coupling region 61 than the third point and corresponds to the second peripheral region 82. In this embodiment, the second division point Q11 corresponds to the third point, and the second division point Q14 corresponds to the fourth point.

[0065] By satisfying equation (2) above, variations in color uniformity in the first predetermined direction A1 of the field of view 8 can be reduced. Furthermore, if the division efficiency E2 is greater than the division efficiency E1 and the division efficiency E4 is greater than the division efficiency E3, variations in brightness in the first predetermined direction A1 of the field of view 8 can be reduced.

[0066] The uniformity of color in the second predetermined direction A2 of the field of view 8 was evaluated by varying the dispersion efficiency at the first division point P of the first extended region 521 and the dispersion efficiency at the second division point Q of the second extended region 621. As a result, it was confirmed that the variation in the uniformity of color in the second predetermined direction A2 of the field of view 8 can be reduced when the first extended region 521 and the second extended region 621 satisfy the following equation (3). Therefore, in this embodiment, the first extended region 521 and the second extended region 621 are configured to satisfy the following equation (3).

[0067]

number

[0068] The splitting efficiency E5 is the splitting efficiency for the first light L11 at the fifth point. The splitting efficiency E6 is the splitting efficiency for the first light L11 at the sixth point. The fifth and sixth points are selected from among a plurality of first splitting points P, specifically from the first splitting points P21, P31, P41, first splitting points P22, P32, P42, first splitting points P23, P33, P43, and first splitting points P24, P34, P44, which are aligned in the third propagation direction to split the first light L12 propagating in the third propagation direction corresponding to the second predetermined direction A2. The third propagation direction coincides with the second direction D2. The fifth point corresponds to the third peripheral region 83, and the sixth point is further from the first coupling region 51 than the fifth point and corresponds to the fourth peripheral region 84. In this embodiment, the pairs of first division points P21 and P41, P22 and P42, P23 and P43, and P24 and P44 correspond to the fifth and sixth points, respectively.

[0069] The division efficiency E7 is the division efficiency for the second light L21 at the seventh point. The division efficiency E8 is the division efficiency for the second light L21 at the eighth point. The seventh and eighth points are selected from among a plurality of second division points Q, specifically from the second division points Q21, Q31, Q41, second division points Q22, Q32, Q42, second division points Q23, Q33, Q43, and second division points QP24, Q34, Q44, which are aligned in the fourth propagation direction to divide the second light L22 propagating in the fourth propagation direction corresponding to the second predetermined direction A2. The fourth propagation direction coincides with the fourth direction D4. The seventh point corresponds to the third peripheral region 83, and the eighth point is further from the second coupling region 61 than the seventh point and corresponds to the fourth peripheral region 84. In this embodiment, the pairs of second division points Q21 and Q41, Q22 and Q42, Q23 and Q43, and Q24 and Q44 correspond to the seventh and eighth points, respectively.

[0070] By satisfying equation (3) above, variations in color uniformity in the second predetermined direction A2 of the field of view 8 can be reduced. Furthermore, if the division efficiency E6 is greater than the division efficiency E5 and the division efficiency E8 is greater than the division efficiency E7, variations in brightness in the second predetermined direction A2 of the field of view 8 can be reduced.

[0071] The projection optical system 7 projects image light L1 that forms the image output from the display element 2. In this way, the projection optical system 7 causes the image light L1 from the display element 2 to enter the light guide member 4. As shown in Figure 1, the projection optical system 7 is located between the display element 2 and the first coupling region 51 and the second coupling region 61 of the light guide member 4. For example, the projection optical system 7 collimates the image light L1 from the display element 2 and causes it to enter the first coupling region 51 and the second coupling region 61. The projection optical system 7 causes the image light L1 to enter the first coupling region 51 and the second coupling region 61 as substantially collimated light. The projection optical system 7 is, for example, a biconvex lens.

[0072] [1.1.2 Examples] The following describes embodiments of the light guide member 4. Embodiments 1 to 9 relate to the first extended region 521 and the second extended region 621. Embodiments 1 to 9 are merely some of the feasible embodiments of the first extended region 521 and the second extended region 621 of the light guide member 4.

[0073] [1.1.2.1 Example 1] In Example 1, the extraction efficiency of the first extended region 521 is 80%. The extraction efficiency of the second extended region 621 is also 80%. The number of divisions of the first light L11 in the first extended region 521 and the number of divisions of the second light L21 in the second extended region 621 are 10, and the number of first division points P and second division points Q are also 10. In the first extended region 521, the internal absorption rate for the first light L11 is 0, and in the second extended region 621, the internal absorption rate for the second light L21 is 0.2% / mm. For simplification, the distance between the first division points P and the distance between the second division points Q were set to 10 mm.

[0074] In the first extended region 521, the division efficiency of the first division point P is set so that the amount of light extracted at the first division point P is equal to each other (here, 0.08% of the incident light amount of the first light L11). In the second extended region 621, the division efficiency of the second division point Q is set so that the amount of light extracted at the second division point Q is equal to each other (here, 0.08% of the incident light amount of the second light L21). When the amount of light extracted at the first division point P is equal to each other and the amount of light extracted at the second division point Q is equal to each other, the ratio of the amount of light of the second emitted light L23 to the amount of light of the first emitted light L13 at multiple points in the field of view region 8 becomes equal to each other, thus improving the uniformity of color.

[0075] Figure 5 is a graph of the division efficiency for Example 1. In Figure 5, curve F1 shows the change in division efficiency with respect to the number of divisions in the first extended region 521. Curve F2 shows the change in division efficiency with respect to the number of divisions in the second extended region 621. The division efficiency for a division count of "1" in the first extended region 521 corresponds to the division efficiency E1 for the first light source L11 at the first point. The division efficiency for a division count of "10" in the first extended region 521 corresponds to the division efficiency E2 for the first light source L11 at the second point. The division efficiency for a division count of "1" in the second extended region 621 corresponds to the division efficiency E3 for the second light source L21 at the third point. The division efficiency for a division count of "10" in the second extended region 621 corresponds to the division efficiency E4 for the second light source L21 at the fourth point. This point is the same for Examples 2 to 5.

[0076] In Example 1, as the number of divisions increases, the division efficiency of the second extended region 621 becomes higher than that of the first extended region 521. In Example 1, the division efficiency E1 is 0.08, the division efficiency E2 is 0.29, the division efficiency E3 is 0.08, and the division efficiency E4 is 0.44. The division efficiency E2 is greater than the division efficiency E1. The division efficiency E4 is greater than the division efficiency E3. If we let the left side of equation (2) be ε, then the left side ε of equation (2) is 0.65, and thus satisfies equation (2).

[0077] Here, as a comparative example, consider the case where the division efficiencies at the first division point P are equal and the division efficiencies at the second division point Q are equal. In the comparative example, the division efficiency at the first division point P that makes the extraction efficiency of the first extended region 521 80% is 0.15, and the division efficiency that makes the extraction efficiency of the second extended region 621 80% is 0.17. In this case, the left-hand side ε of equation (2) is 1.28, and does not satisfy equation (2) above.

[0078] Figure 6 is a graph of the extracted light intensity for the comparative example. In Figure 6, curve G1 shows the change in extracted light intensity with respect to the number of divisions in the first extended region 521. Curve G2 shows the change in extracted light intensity with respect to the number of divisions in the second extended region 621. The values ​​on the vertical axis (extracted light intensity) in Figure 6 are the values ​​when the incident light intensity of the first light L11 and the incident light intensity of the second light L21 are each set to 1. From Figure 6, it can be seen that in the comparative example, the extracted light intensity in the first extended region 521 and the second extended region 621 decreases as the number of divisions increases. Figure 7 is a graph showing the change in the ratio of the light intensity of the first emitted light L13 to the light intensity of the second emitted light L23 at multiple points in the field of view region 8, that is, the ratio of the light intensity of the first light L11 to the light intensity of the second light L21 in the image light L1 at each point in the field of view region 8. As is clear from Figure 7, the ratio of the light intensity of the first emitted light L13 to the light intensity of the second emitted light L23 at multiple points in the field of view region 8 increases as the number of divisions increases. In other words, the more divisions there are, the lower the proportion of the second light source L21 in the image light source L1 becomes at each point in the field of view 8, thus worsening the uniformity of the color.

[0079] [1.1.2.2 Example 2] Example 2 differs from Example 1 in that the extraction efficiency of the second extended region 621 is 60%. In Example 2, the division efficiency of the second division point Q is set such that the extracted light amounts at the second division point Q are equal (here, 0.06% of the incident light amount of the second light L21). In Example 2 as well, the ratio of the light amount of the first emitted light L13 and the light amount of the second emitted light L23 at multiple points in the field of view region 8 is equal, thereby improving color uniformity.

[0080] Figure 8 is a graph of the division efficiency for Example 2. In Example 2, the division efficiency of the second extended region 621 is generally lower than that of the first extended region 521. In Example 2, the division efficiency E1 is 0.08, the division efficiency E2 is 0.29, the division efficiency E3 is 0.06, and the division efficiency E4 is 0.17. The division efficiency E2 is greater than the division efficiency E1. The division efficiency E4 is greater than the division efficiency E3. The left-hand side ε of equation (2) is 0.69, and satisfies equation (2) above.

[0081] [1.1.2.3 Example 3] Example 3 differs from Example 1 in that the internal absorption rate for the second light L21 in the second extended region 621 is 0.1% / mm. In Example 3 as well, the ratio of the light intensity of the first emitted light L13 to the light intensity of the second emitted light L23 at multiple points in the field of view region 8 is equal to each other, thus improving color uniformity.

[0082] Figure 9 is a graph of the division efficiency for Example 3. In Example 3, although not to the same extent as in Example 1, the division efficiency of the second extended region 621 becomes higher than that of the first extended region 521 as the number of divisions increases. In Example 3, the division efficiency E1 is 0.08, the division efficiency E2 is 0.29, the division efficiency E3 is 0.08, and the division efficiency E4 is 0.35. The division efficiency E2 is greater than the division efficiency E1. The division efficiency E4 is greater than the division efficiency E3. The left side ε of equation (2) is 0.82, and satisfies equation (2) above.

[0083] [1.1.2.4 Example 4] Example 4 differs from Example 1 in that the extraction efficiency of the first extended region 521 is 60%. In Example 4, the division efficiency of the first division point P is set such that the extracted light amounts at the first division point P are equal (here, 0.06% of the incident light amount of the first light L11). In Example 4 as well, the ratio of the light amount of the first emitted light L13 and the light amount of the second emitted light L23 at multiple points in the field of view region 8 are equal, thereby improving color uniformity.

[0084] Figure 10 is a graph of the division efficiency for Example 4. In Example 4, the division efficiency of the second extended region 621 is generally higher than that of the first extended region 521. In Example 4, the division efficiency E1 is 0.06, the division efficiency E2 is 0.13, the division efficiency E3 is 0.08, and the division efficiency E4 is 0.35. The division efficiency E2 is greater than the division efficiency E1. The division efficiency E4 is greater than the division efficiency E3. The left side ε of equation (2) is 0.88, and satisfies equation (2) above.

[0085] [1.1.2.5 Example 5] Example 5 differs from Example 1 in that the extraction efficiencies of the first extended region 521 and the second extended region 621 are each 60%, and the internal absorption rate for the second light L21 in the second extended region 621 is 0.3% / mm. In Example 5, the division efficiency of the first division point P is set so that the extracted light amounts at the first division point P of the first extended region 521 are equal (here, 0.06% of the incident light amount of the first light L11). In the second extended region 621, the division efficiency of the second division point Q is set so that the extracted light amounts at the second division point Q are equal (here, 0.06% of the incident light amount of the second light L21). In Example 5 as well, the ratio of the light amount of the first emitted light L13 and the light amount of the second emitted light L23 at multiple points in the field of view 8 is equal, improving color uniformity.

[0086] Figure 11 is a graph of the division efficiency for Example 5. In Example 5, as in Example 1, the division efficiency of the second extended region 621 becomes higher than that of the first extended region 521 as the number of divisions increases. In Example 5, the division efficiency E1 is 0.06, the division efficiency E2 is 0.13, the division efficiency E3 is 0.06, and the division efficiency E4 is 0.20. The division efficiency E2 is greater than the division efficiency E1. The division efficiency E4 is greater than the division efficiency E3. The left side ε of equation (2) is 0.64, and satisfies equation (2) above.

[0087] [1.1.2.6 Example 6] In Example 6, the extraction efficiency of the first extended region 521 is 60%. The extraction efficiency of the second extended region 621 is 60%. The number of divisions of the first light L11 in the first extended region 521 and the number of divisions of the second light L21 in the second extended region 621 are 15, and the number of first division points P and second division points Q are also 15. In the first extended region 521, the internal absorption rate for the first light L11 is 0, and in the second extended region 621, the internal absorption rate for the second light L21 is 0.1% / mm. For simplification, the distance between the first division points P and the distance between the second division points Q were set to 10 mm.

[0088] In the first extended region 521, the division efficiency of the first division point P is set so that the amount of light extracted at the first division point P is equal to each other (here, 0.04% of the incident light amount of the first light L11). In the second extended region 621, the division efficiency of the second division point Q is set so that the amount of light extracted at the second division point Q is equal to each other (here, 0.04% of the incident light amount of the second light L21). In Example 6 as well, the ratio of the light amount of the first emitted light L13 and the light amount of the second emitted light L23 at multiple points in the field of view region 8 is equal to each other, thereby improving color uniformity.

[0089] Figure 12 is a graph of the division efficiency for Example 1. In Figure 12, curve F1 shows the change in division efficiency with respect to the number of divisions in the first extended region 521. Curve F2 shows the change in division efficiency with respect to the number of divisions in the second extended region 621. The division efficiency for a division count of "1" in the first extended region 521 corresponds to the division efficiency E1 for the first light source L11 at the first point. The division efficiency for a division count of "15" in the first extended region 521 corresponds to the division efficiency E2 for the first light source L11 at the second point. The division efficiency for a division count of "1" in the second extended region 621 corresponds to the division efficiency E3 for the second light source L21 at the third point. The division efficiency for a division count of "15" in the second extended region 621 corresponds to the division efficiency E4 for the second light source L21 at the fourth point. This point is the same for Examples 7 to 9.

[0090] In Example 6, as the number of divisions increases, the division efficiency of the second extended region 621 becomes higher than that of the first extended region 521. In Example 1, the division efficiency E1 is 0.04, the division efficiency E2 is 0.09, the division efficiency E3 is 0.04, and the division efficiency E4 is 0.11. The division efficiency E2 is greater than the division efficiency E1. The division efficiency E4 is greater than the division efficiency E3. The left-hand side ε of equation (2) is 0.79, and satisfies equation (2) above.

[0091] [1.1.2.7 Example 7] Example 7 differs from Example 6 in that the internal absorption rate for the second light L21 in the second extended region 621 is 0.3% / mm. In Example 7 as well, the ratio of the light intensity of the first emitted light L13 to the light intensity of the second emitted light L23 at multiple points in the field of view region 8 is equal to each other, thus improving color uniformity.

[0092] Figure 13 is a graph of the division efficiency for Example 7. In Example 7, compared to Example 6, the division efficiency of the second extended region 621 becomes higher than that of the first extended region 521 as the number of divisions increases. In Example 7, the division efficiency E1 is 0.04, the division efficiency E2 is 0.09, the division efficiency E3 is 0.04, and the division efficiency E4 is 0.20. The division efficiency E2 is greater than the division efficiency E1. The division efficiency E4 is greater than the division efficiency E3. The left side ε of equation (2) is 0.46, and satisfies equation (2) above.

[0093] [1.1.2.8 Example 8] Example 8 differs from Example 6 in that the extraction efficiency of the first extended region 521 is 75%. In Example 8, the division efficiency of the first division point P is set such that the extracted light amounts at the first division point P are equal (here, 0.05% of the incident light amount of the first light L11). In Example 8 as well, the ratio of the light amount of the first emitted light L13 and the light amount of the second emitted light L23 at multiple points in the field of view region 8 is equal, improving color uniformity.

[0094] Figure 14 is a graph of the division efficiency for Example 8. In Example 8, the division efficiency of the second extended region 621 is generally lower than that of the first extended region 521. In Example 8, the division efficiency E1 is 0.05, the division efficiency E2 is 0.17, the division efficiency E3 is 0.04, and the division efficiency E4 is 0.11. The division efficiency E2 is greater than the division efficiency E1. The division efficiency E4 is greater than the division efficiency E3. The left-hand side ε of equation (2) is 0.74, and satisfies equation (2) above.

[0095] [1.1.2.9 Example 9] Example 9 differs from Example 8 in that the internal absorption rate for the second light L21 in the second extended region 621 is 0.3% / mm. In Example 9 as well, the ratio of the light intensity of the first emitted light L13 to the light intensity of the second emitted light L23 at multiple points in the field of view region 8 is equal to each other, thus improving color uniformity.

[0096] Figure 15 is a graph of the division efficiency for Example 9. In Example 9, the division efficiency of the second extended region 621 is lower than that of the first extended region 521 when the number of divisions is small, but as the number of divisions increases, the division efficiency of the second extended region 621 becomes higher than that of the first extended region 521. In Example 9, the division efficiency E1 is 0.05, the division efficiency E2 is 0.17, the division efficiency E3 is 0.04, and the division efficiency E4 is 0.20. The division efficiency E2 is greater than the division efficiency E1. The division efficiency E4 is greater than the division efficiency E3. The left side ε of equation (2) is 0.43, and satisfies equation (2) above.

[0097] [1.1.2.10 Other Examples] Examples 1 to 9 all relate to the first extended region 521 and the second extended region 621. However, the conditions of Examples 1 to 9 are applicable to the first emission region 522 and the second emission region 622 of the light guide member 4. That is, the first emission region 522 and the second emission region 622 The first extended region 521 and the second extended region 621 may be designed in the same manner. Examples 1 to 9 described above can be applied to the first ejection region 522 and the second ejection region 622 by substituting the division efficiencies E1, E2, E3, and E4 with division efficiencies E5, E6, E7, and E8, respectively.

[0098] In Examples 1 to 9, the division efficiency of the first extended region 521 and the second extended region 621 increases monotonically as the number of divisions increases. However, the division efficiency does not necessarily have to continue increasing with increasing number of divisions, and may have a portion that does not change (flat).

[0099] [1.1.3 Effects, etc.] The optical system 3 described above includes a light guide member 4 that guides the image light L1, which forms the image output from the display element 2, as a virtual image into the user's field of view 8. The image light L1 includes a first light L11 in a first wavelength band and a second light L21 in a second wavelength band shorter than the first wavelength band. The light guide member 4 has a first coupling region 51, a first dividing region 52, a second coupling region 61, and a second dividing region 62. The first coupling region 51 causes the first light L11 of the image light L1 to be incident into the light guide member 4 so that the first light L11 propagates within the light guide member 4. The first dividing region 52 has a plurality of first dividing points P that divide the first light L11 that has been incident into the light guide member 4 from the first coupling region 51, and emits a plurality of first emitted light L13 into the field of view 8. The second coupling region 61 causes the second light L21 from the image light L1 to be incident into the light guide member 4 so that the second light L21 propagates within the light guide member 4. The second dividing region 62 has a plurality of second dividing points Q that divide the second light L21 that has been incident into the light guide member 4 from the second coupling region 61, and emits a plurality of second emitted light L23 into the field of view region 8. The field of view region 8 has a first peripheral region 81 on the side of the first end 8a in a predetermined direction A1 in the plane of the field of view region 8, and a second peripheral region 82 on the side of the second end 8b in the predetermined direction A1. The plurality of first dividing points P include first dividing point P11 (first point) and first dividing point P14 (second point) that are aligned in the first direction D1 (first propagation direction) so as to divide the first light L11 that propagates in the first direction D1 (first propagation direction) corresponding to the predetermined direction A1. The first division point P11 (first point) corresponds to points R21, R31, and R41 in the first peripheral region 81. The first division point P14 (second point) is further from the first coupling region 51 than the first division point P11 (first point) and corresponds to points R24, R34, and R44 in the second peripheral region 82. The multiple second division points Q include second division points Q11 (third point) and fourth point Q14 (fourth point) which are aligned in the third direction D3 (second propagation direction) to divide the second light L21 propagating in the third direction D3 (second propagation direction) corresponding to a predetermined direction A1. The second division point Q11 (third point) corresponds to points R21, R31, and R41 in the first peripheral region 81. The second division point Q14 (the fourth point) is further from the second connecting region 61 than the second division point Q11 (the third point), and corresponds to points R24, R34, and R44 within the second peripheral region 82.If we denote the division efficiency for the first light L11 at the first division point P11 (first point) as E1, the division efficiency for the first light L11 at the first division point P14 (second point) as E2, the division efficiency for the second light L21 at the second division point Q11 (third point) as E3, and the division efficiency for the second light L21 at the second division point Q14 (fourth point) as E4, then the division efficiencies E1, E2, E3, and E4 satisfy the following equation (4).

number

[0100] In optical system 3, the division efficiency E2 is greater than the division efficiency E1. The division efficiency E4 is greater than the division efficiency E3. This configuration enables improved uniformity of brightness in the first predetermined direction A1 of the field of view 8.

[0101] In optical system 3, the first division point P11 (first point) and the second division point Q11 (third point) correspond to the same points R21, R31, and R41 in the first peripheral region 81. The first division point P14 (second point) and the second division point Q14 (fourth point) correspond to the same points R24, R34, and R44 in the second peripheral region 82. This configuration enables further improvement of color uniformity.

[0102] In the optical system 3, the first peripheral region 81 occupies one-quarter of the field of view 8 from its first end 8a in the first predetermined direction A1. The second peripheral region 82 occupies one-quarter of the field of view 8 from its second end 8b in the first predetermined direction A1. This configuration enables further improvement of color uniformity.

[0103] In the optical system 3, the first divided region 52 has a first expanded region 521 and a first emission region 522. The first expanded region 521 divides the first light L11 propagating within the light guide member 4, directing a plurality of first light beams L12 aligned in a first direction D1 perpendicular to the thickness direction of the light guide member 4 toward the first emission region 522. The first emission region 522 divides the plurality of first light beams L12 from the first expanded region 521, emitting a plurality of first light beams L12 aligned in a second direction D2 perpendicular to the thickness direction of the light guide member 4 and intersecting the first direction D1 as a plurality of first emitted light beams L13 toward the field of view region 8. The second divided region 62 has a second expanded region 621 and a second emission region 622. The second extended region 621 divides the second light L21 propagating within the light guide member 4, directing multiple second light beams L22 aligned in the third direction D3 corresponding to the first direction D1 towards the second emission region 622. The second emission region 622 divides the multiple second light beams L22 from the second extended region 621, emitting multiple second light beams L22 aligned in the fourth direction D4 corresponding to the second direction D2 as multiple second emission beams L23 into the field of view region 8. The first extended region 521 has a first point and a second point, while the second extended region 621 has a third point and a fourth point. This configuration enables the extension of the pupil of the image light L1 in two directions.

[0104] In the optical system 3, the length of the first extended region 521 in the first direction D1, the length of the first exit region 522 in the second direction D2, the length of the second extended region 621 in the third direction D3, and the length of the second extended region 621 in the fourth direction D4 are all 100 mm or more. This configuration can provide the user with a field of view 8 of sufficient size.

[0105] In the optical system 3, the field of view 8 has a third peripheral region 83 on the third end 8c side in the second predetermined direction A2 that intersects the first predetermined direction A1, which is a predetermined direction A1, and a fourth peripheral region 84 on the fourth end 8d side in the second predetermined direction A2, within the plane of the field of view 8. The plurality of first division points P include first division points P21 to P24 (fifth point) and first division points P41 to P44 (sixth point) that are aligned in the second direction D2 (third propagation direction) to divide the first light L12 propagating in the second direction D2 (third propagation direction) corresponding to the second predetermined direction A2. The first division points P21 to P24 (fifth point) correspond to points R21, R22, R23, and R24 in the third peripheral region 83. The first division points P41-P44 (sixth point) are further from the first coupling region 51 than the first division points P21-P24 (fifth point) and correspond to points R41, R42, R43, and R44 in the fourth peripheral region 84. The multiple second division points Q include second division points Q21-Q24 (seventh point) and second division points Q41-Q44 (eighth point) which are aligned in the fourth direction D4 (fourth propagation direction) to divide the second light L22 propagating in the fourth direction D4 (fourth propagation direction) corresponding to the second predetermined direction A2. The second division points Q21-Q24 (seventh point) correspond to points R21, R22, R23, and R24 in the third peripheral region 83. The second division points Q41-Q44 (point 8) are further from the second bonding region 61 than the second division points Q21-Q24 (point 7), and correspond to points R41, R42, R43, and R44 within the fourth peripheral region 84. If we let E5 be the division efficiency for the first light L12 at the first division points P21-P24 (point 5), E6 be the division efficiency for the first light L12 at the first division points P41-P44 (point 6), E7 be the division efficiency for the second light L22 at the second division points Q21-Q24 (point 7), and E8 be the division efficiency for the second light L22 at the second division points Q41-Q44 (point 8), then the division efficiencies E5, E6, E7, and E8 satisfy equation (5) below.

number

[0106] In optical system 3, the division efficiency E6 is greater than the division efficiency E5. The division efficiency E8 is greater than the division efficiency E7. This configuration enables improved brightness uniformity in the second predetermined direction A2 of the field of view 8.

[0107] In optical system 3, the first division points P21-P24 (5th point) and the second division points Q21-Q24 (7th point) correspond to the same points R21-R24 in the third peripheral region 83. The first division points P41-P44 (6th point) and the second division points Q41-Q44 (8th point) correspond to the same points R41-R44 in the fourth peripheral region 84. This configuration enables improved color uniformity.

[0108] In the optical system 3, the third peripheral region 83 occupies one-quarter of the field of view 8 from the third end 8c in the second predetermined direction A2. The fourth peripheral region 84 occupies one-quarter of the field of view 8 from the fourth end 8d in the second predetermined direction A2. This configuration enables improved color uniformity.

[0109] In the optical system 3, the light guide member 4 comprises first and second substrates 5 and 6 facing each other with an air layer 41 in between. The first bonding region 51 and the first dividing region 52 are provided on the first substrate 5. The second bonding region 61 and the second dividing region 62 are provided on the second substrate 6. This configuration enables improved color uniformity.

[0110] In the optical system 3, the first divided region 52 has a diffraction grating as a structure that defines a plurality of first divided points P. The second divided region 62 has a diffraction grating as a structure that defines a plurality of second divided points Q. This configuration enables improved color uniformity.

[0111] In optical system 3, the first wavelength band is between 510 nm and 780 nm. The second wavelength band is between 380 nm and 480 nm. This configuration enables improved color uniformity.

[0112] In the optical system 3, the refractive index of the light guide member 4 with respect to the d line is greater than 1.7. This configuration can reduce pupil breaks in the image light L1 in the field of view 8.

[0113] In the optical system 3, the internal absorption rate of the light guide member 4 for the second light L21 is greater than 0.05% / mm and less than 0.50%. This configuration enables improved color uniformity.

[0114] The optical system 3 further includes a projection optical system 7 that directs the image light L1 as substantially collimated light into the first coupling region 51 and the second coupling region 61 of the light guide member 4. This configuration enables improved color uniformity.

[0115] In the optical system 3, multiple first emitted light rays L13 are parallel to each other. Multiple second emitted light rays L23 are parallel to each other. This configuration can reduce pupil breaks in the image light L1 in the field of view 8.

[0116] The image display device 1 described above comprises an optical system 3 and a display element 2. This configuration enables improved color uniformity.

[0117] [1.2 Embodiment 2] [1.2.1 Structure] Figure 16 is a schematic diagram of an example configuration of the image display device 1A. The image display device 1A differs from the image display device 1 in that it has an optical system 3A that is different from the optical system 3 of the image display device 1. The optical system 3A differs from the optical system 3 in that it has a light guide member 4A that is different from the light guide member 4 of the optical system 3.

[0118] Similar to the light guide member 4, the light guide member 4A guides the image light L1 that forms the image output from the display element 2 into the user's field of view area 8 as a virtual image. The light guide member 4A in Figure 16 is composed of a single substrate.

[0119] The light guide member 4A comprises a main body 40, a first coupling region 51, a first dividing region 52, a second coupling region 61, and a second dividing region 62.

[0120] The main body 40 is formed of a material that is transparent in the visible light region and has a first surface 40a and a second surface 40b in the thickness direction. In this embodiment, the first surface 40a is treated as the front surface of the light guide member 4A, and the second surface 40b is treated as the rear surface of the light guide member 4A. The refractive index of the main body 40 with respect to the d line (wavelength 587.562 nm) is greater than 1.7. The internal absorption rate of the main body 40 with respect to the first light L11 is substantially 0. The internal absorption rate of the main body 40 with respect to the second light L21 is greater than 0.05% / mm and less than 0.50%. In this embodiment, the main body 40 is in the shape of a rectangular plate. As shown in Figure 16, the main body 40 is positioned with the first surface 40a facing the display element 2 side and the second surface 40b facing the viewing area 8 side.

[0121] Figure 17 is a front view of the light guide member 4A as seen from the display element 2 side. The first coupling region 51 and the first dividing region 52 are provided on the first surface 40a of the main body portion 40. In this embodiment, the first coupling region 51 and the first dividing region 52 are formed on the first surface 40a of the main body portion 40. The first coupling region 51 and the first dividing region 52 do not need to be formed by processing the first surface 40a of the main body portion 40 itself; they may be provided by joining a separate member to the first surface 40a of the main body portion 40.

[0122] Figure 18 is a rear view of the light guide member 4A as seen from the field of view area 8 side. The second coupling area 61 and the second dividing area 62 are provided on the second surface 40b of the main body portion 40. In this embodiment, the second coupling area 61 and the second dividing area 62 are formed on the second surface 40b of the main body portion 40. The second coupling area 61 and the second dividing area 62 do not need to be formed by processing the second surface 40b of the main body portion 40 itself; they may be provided by joining a separate member to the second surface 40b of the main body portion 40.

[0123] In the light guide member 4A shown in Figure 16, the first coupling region 51 and the first dividing region 52 (first extended region 521 and first emission region 522) of the light guide member 4A overlap with the second coupling region 61 and the second dividing region 62 (second extended region 621 and second emission region 622) of the second substrate 6, respectively, when viewed from the thickness direction of the light guide member 4A.

[0124] Image light L1 from the display element 2 is incident on the first coupling region 51 of the first surface 40a of the light guide member 4A, and the first coupling region 51 directs the first light L11 of the image light L1 towards the first dividing region 52. In the first dividing region 52, the first extended region 521 divides the first light L11 from the first coupling region 51 into multiple first light L12 at multiple first division points P11 to P14 and directs them towards the first emission region 522. The first emission region 522 divides the multiple first light L12 at multiple first division points P21 to P24, P31 to P34, and P41 to P44 and emits multiple first emitted light L13 into the field of view region 8. The image light L1 that has passed through the first coupling region 51 is incident on the second coupling region 61 of the second surface 40b of the light guide member 4A. The second combining region 61 directs the second light L21 of the image light L1 towards the second dividing region 62. In the second dividing region 62, the second extended region 621 divides the second light L21 from the second combining region 61 into multiple second light L22 at multiple second division points Q11 to Q14 and directs them towards the second emission region 622. The second emission region 622 divides the multiple second light L22 at multiple second division points Q21 to Q24, Q31 to Q34, and Q41 to Q44, and emits multiple second emission light L23 into the field of view region 8.

[0125] In the light guide member 4A, similar to the light guide member 4, the first emitted light L13 from the first division points P21~P24, P31~P34, and P41~P44 of the first emission region 522 reaches multiple points R21~R24, R31~R34, and R41~R44 in the field of view region 8, respectively. The second emitted light L23 from the second division points Q21~Q24, Q31~Q34, and Q41~Q44 of the second emission region 622 reaches multiple points R21~R24, R31~R34, and R41~R44 in the field of view region 8, respectively. Therefore, a virtual image is formed at multiple points R21~R24, R31~R34, and R41~R44 in the field of view region 8 by the first emitted light L13 and the second emitted light L23.

[0126] [1.2.2 Effects, etc.] In the optical system 3A described above, the light guide member 4A is composed of a single substrate. This configuration enables miniaturization of the light guide member 4A.

[0127] The image display device 1A described above comprises an optical system 3A and a display element 2. This configuration enables improved color uniformity.

[0128] [2. Variant] The embodiments of this disclosure are not limited to those described above. The embodiments can be modified in various ways depending on the design, etc., as long as the objectives of this disclosure can be achieved. The following lists some modifications of the embodiments. The modifications described below can be combined and applied as appropriate.

[0129] In one modified example, in the light guide members 4 and 4A, the first extended region 521 and the second extended region 621 satisfy equation (2) above, but the first emission region 522 and the second emission region 622 do not necessarily satisfy equation (3) above. Instead of the first extended region 521 having the first and second points and the second extended region 621 having the third and fourth points, the first emission region 522 may have the first and second points and the second emission region 622 may have the third and fourth points. This is similar to the case where the first extended region 521 and the second extended region 621 do not satisfy equation (2) above, but the first emission region 522 and the second emission region 622 satisfy equation (3) above.

[0130] In one modified example, the number of first division points P and the number of second division points Q are not particularly limited. In Embodiment 1, the first division points P and the second division points Q are arranged in a 4x4 matrix, but this is merely one example.

[0131] In one modified example, the first divided region 52 does not necessarily have to have both the first divided region 52 and the first emission region 522. In this case, the first divided region 52 expands the pupil of the image light L1 in only one direction. The same applies to the second divided region 62.

[0132] In one modified example, the light intensity of the second light source L21 may be greater than that of the first light source L11. The second light source L21 is more easily absorbed by the light guide member 4 than the first light source L11. Therefore, by setting the light intensity of the second light source L21 to be greater than that of the first light source L11 beforehand, the effect of internal absorption by the light guide member 4 can be reduced. This configuration enables further improvement of color uniformity.

[0133] In one modified example, if equation (2) above is satisfied, the division efficiency E2 may be less than or equal to the division efficiency E1, and the division efficiency E4 may be less than or equal to the division efficiency E3. Similarly, if equation (3) above is satisfied, the division efficiency E6 may be less than or equal to the division efficiency E5, and the division efficiency E8 may be less than or equal to the division efficiency E7.

[0134] In one modified example, the first division point P11 (first point) and the second division point Q11 (third point) do not necessarily correspond to the same points R21, R31, and R41 within the first peripheral region 81; they may correspond to different points within the first peripheral region 81. The first division point P14 (second point) and the second division point Q14 (fourth point) do not necessarily correspond to the same points R24, R34, and R44 within the second peripheral region 82; they may correspond to different points within the second peripheral region 82. The first division points P21 to P24 (fifth points) and the second division points Q21 to Q24 (seventh points) do not necessarily correspond to the same points R21 to R24 within the third peripheral region 83; they may correspond to different points within the third peripheral region 83. The first division points P41-P44 (sixth point) and the second division points Q41-Q44 (eighth point) do not necessarily correspond to the same points R41-R44 within the fourth peripheral region 84; they may correspond to different points within the fourth peripheral region 84.

[0135] In one modified example, the first peripheral region 81 may occupy less than 1 / 4 of the field of view 8 from the first edge 8a of the field of view 8 in the first predetermined direction A1. For example, the first peripheral region 81 may occupy 1 / 8 of the field of view 8 from the first edge 8a of the field of view 8 in the first predetermined direction A1, and may coincide with the first edge 8a of the field of view 8. By narrowing the range of the first peripheral region 81, further improvement in color uniformity becomes possible. The same applies to the second peripheral region 82, the third peripheral region 83, and the fourth peripheral region 84.

[0136] In one modified example, the length of the first extended region 521 in the first direction D1, the length of the first ejection region 522 in the second direction D2, the length of the second extended region 621 in the third direction D3, and the length of the second extended region 621 in the fourth direction D4 do not all have to be 100 mm or more, and at least one of them may be 100 mm or more.

[0137] In one modified example, the first divided region 52 may have a volume hologram element (holographic diffraction grating) or a half mirror instead of a diffraction grating as a structure defining a plurality of first divided points P. Furthermore, the first divided region 52 may have at least one selected from the group consisting of a diffraction grating, a volume hologram element, and a half mirror as a structure defining a plurality of first divided points P. Similarly, the second divided region 62 may have at least one of a diffraction grating, a volume hologram element, and a half mirror as a structure defining a plurality of second divided points Q.

[0138] In one modified example, the first wavelength band is not limited to 510 nm to 780 nm. The second wavelength band is not limited to 380 nm to 480 nm. The refractive index of the light guide member 4 with respect to the d line may be 1.7 or less. The internal absorption rate of the light guide member 4 with respect to the second light L21 is not limited to a range greater than 0.05% / mm and less than 0.50%, but is sufficient as long as it is higher than the internal absorption rate with respect to the first light L11.

[0139] In one modified example, the light guide members 4 and 4A may have multiple sets of coupling regions and dividing regions corresponding to multiple lights of different wavelength bands (different colors) contained in the image light L1. For example, the light guide member 4 may have a set of coupling region and dividing region for expanding the pupil of red light in the image light L1, a set of coupling region and dividing region for expanding the pupil of green light in the image light L1, and a set of coupling region and dividing region for expanding the pupil of blue light in the image light L1. This configuration enables further improvement of color uniformity.

[0140] For example, the light guide member may comprise first to third substrates. The first and second substrates face each other with a first air layer in between. The second and third substrates face each other with a second air layer in between. The first substrate may have a pair of coupling region and dividing region for expanding the pupil of red light L1 of the image light. The second substrate may have a pair of coupling region and dividing region for expanding the pupil of green light L1 of the image light. The third substrate may have a pair of coupling region and dividing region for expanding the pupil of blue light L1 of the image light. The first to third substrates may be arranged such that the image light L1 is incident on the coupling region of the first substrate, the coupling region of the second substrate, and the coupling region of the third substrate in this order.

[0141] For example, the light guide member may comprise a single substrate comprising a first set of a coupling region and a dividing region for expanding the pupil of the red light L1 image, a second set of a coupling region and a dividing region for expanding the pupil of the green light L1 image, and a third set of a coupling region and a dividing region for expanding the pupil of the blue light L1 image. The first set may be a diffraction grating composed of an uneven structure provided on a first surface in the thickness direction of the substrate. The second set may be a volume hologram element provided inside the substrate. The third set may be a diffraction grating composed of an uneven structure provided on a second surface in the thickness direction of the substrate. The substrate may be arranged so that its first surface faces the projection optical system.

[0142] In one modified example, the order in which the image light L1 is incident on the first coupling region 51 and the second coupling region 61 is not particularly limited. In the light guide member 4 of Embodiment 1, the first substrate 5 is located between the projection optical system 7 and the second substrate 6 in the optical path of the image light L1 from the projection optical system 7. In contrast, the second substrate 6 may be located between the first substrate 5 and the projection optical system 7 in the optical path of the image light L1 from the projection optical system 7. In this case, the loss of the second light L21 in the second wavelength band generated by the first substrate 5 can be reduced. This is also true when the light guide member has three or more coupling regions.

[0143] In one modified example, the projection optical system 7 may comprise a first optical element and a second optical element, rather than being a single optical element. The first optical element is, for example, a cemented lens combining a negative meniscus lens and a biconvex lens, and the second optical element is a cemented lens combining a positive meniscus lens and a negative meniscus lens. Note that the optical system 3 does not necessarily have to include the projection optical system 7.

[0144] In embodiments 1 and 2, the projection optical system 7 and the first and second bonding regions 51 and 61 are aligned in a straight line, but the projection optical system 7 and the first and second bonding regions 51 and 61 do not necessarily have to be aligned in a straight line. In other words, the optical path of the image light L1 from the projection optical system 7 to the first and second bonding regions 51 and 61 is not necessarily straight. For example, the image light L1 from the projection optical system 7 may be reflected by a reflector and incident on the first and second bonding regions 51 and 61. In this case, the optical path of the image light L1 from the projection optical system 7 to the first and second bonding regions 51 and 61 is not straight, but for example, L-shaped.

[0145] [3. Appearance] As is clear from the above embodiments and modifications, this disclosure includes the following embodiments. In the following, reference numerals are enclosed in parentheses solely to indicate their correspondence with the embodiments.

[0146] The first embodiment is an optical system (3;3A) comprising a light guide member (4;4A) that guides image light (L1) that forms an image output from a display element (2) into the user's field of view (8) as a virtual image. The image light (L1) includes a first light (L11) in a first wavelength band and a second light (L21) in a second wavelength band with a shorter wavelength than the first wavelength band. The light guide member (4;4A) has a first coupling region (51), a first dividing region (52), a second coupling region (61), and a second dividing region (62). The first coupling region (51) causes the first light (L11) to be incident into the light guide member (4;4A) so that the first light (L11) propagates within the light guide member (4;4A). The first dividing region (52) has a plurality of first dividing points (P) that divide the first light (L11) that has been incident on the light guide member (4;4A) from the first combining region (51), and emits a plurality of first emitted light (L13) into the field of view region (8). The second combining region (61) causes the second light (L21) to be incident on the light guide member (4;4A) so that the second light (L21) propagates through the light guide member (4;4A). The second dividing region (62) has a plurality of second dividing points (Q) that divide the second light (L21) that has been incident on the light guide member (4;4A) from the second combining region (61), and emits a plurality of second emitted light (L23) into the field of view region (8). The field of view region (8) has a first peripheral region (81) on the side of the first end (8a) in a predetermined direction (A1) within the plane of the field of view region (8), and a second peripheral region (82) on the side of the second end (8b) in the predetermined direction (A1). The plurality of first division points (P) include a first point (P11) and a second point (P14) aligned in the first propagation direction (D1) so as to divide the first light (L11) propagating in the first propagation direction (D1) corresponding to the predetermined direction (A1). The first point (P11) corresponds to the points (R21, R31, R41) in the first peripheral region (81). The second point (P14) is further from the first coupling region (51) than the first point (P11) and corresponds to the points (R24, R34, R44) in the second peripheral region (82). The plurality of second division points (Q) include a third point (Q11) and a fourth point (Q14) aligned in the second propagation direction (D3) so as to divide the second light (L21) propagating in the second propagation direction (D3) corresponding to the predetermined direction (A1).The third point (Q11) corresponds to the points (R21, R31, R41) in the first peripheral region (81). The fourth point (Q14) is further from the second bonding region (61) than the third point (Q11) and corresponds to the points (R24, R34, R44) in the second peripheral region (82). If E1 is the division efficiency for the first light (L11) at the first point (P11), E2 is the division efficiency for the first light (L11) at the second point (P14), E3 is the division efficiency for the second light (L21) at the third point (Q11), and E4 is the division efficiency for the second light (L21) at the fourth point (Q14), then the division efficiencies E1, E2, E3, and E4 satisfy the following equation (6).

number

[0147] A second embodiment is an optical system (3;3A) based on the first embodiment. In the second embodiment, the amount of light of the second light (L21) is greater than the amount of light of the first light (L11). This embodiment enables further improvement of color uniformity.

[0148] A third embodiment is an optical system (3;3A) based on the first or second embodiment. In the third embodiment, the division efficiency E2 is greater than the division efficiency E1. The division efficiency E4 is greater than the division efficiency E3. This embodiment enables improved uniformity of brightness in a predetermined direction of the field of view.

[0149] A fourth embodiment is an optical system (3;3A) based on any one of the first to third embodiments. In the fourth embodiment, the first point (P11) and the third point (Q11) correspond to the same points (R21, R31, R41) in the first peripheral region (81). The second point (P14) and the fourth point (Q14) correspond to the same points (R24, R34, R44) in the second peripheral region (82). This embodiment enables further improvement of color uniformity.

[0150] A fifth embodiment is an optical system (3;3A) based on any one of the first to fourth embodiments. In the fifth embodiment, the first peripheral region (81) occupies one-quarter of the field of view (8) from the first end (8a) of the field of view (8) in the predetermined direction (A1). The second peripheral region (82) occupies one-quarter of the field of view (8) from the second end (8b) of the field of view (8) in the predetermined direction (A1). This embodiment enables further improvement of color uniformity.

[0151] The sixth embodiment is an optical system (3;3A) based on any one of the first to fifth embodiments. In the sixth embodiment, the first divided region (52) has a first extended region (521) and a first output region (522). The first extended region (521) divides the first light (L11) propagating within the light guide member (4;4A), thereby directing a plurality of first light rays (L12) aligned in a first direction (D1) perpendicular to the thickness direction of the light guide member (4;4A) toward the first output region (522). The first emission region (522) emits multiple first light beams (L13) into the field of view region (8) as the multiple first emitted light beams (L13) by splitting the multiple first light beams (L12) from the first extended region (521) and aligning in a second direction (D2) that is perpendicular to the thickness direction of the light guide member (4;4A) and intersects the first direction (D1). The second divided region (62) has a second extended region (621) and a second emission region (622). The second extended region (621) directs multiple second light beams (L22) aligning in a third direction (D3) corresponding to the first direction (D1) towards the second emission region (622) by splitting the second light beams (L21) propagating within the light guide member (4;4A). The second emission region (622) emits multiple second light beams (L23) arranged in a fourth direction (D4) corresponding to the second direction (D2) by dividing the multiple second light beams (L22) from the second extension region (621) into the field of view region (8) as the multiple second emitted light beams (L23). The first extension region (521) has the first and second points and the second extension region (621) has the third and fourth points, or the first emission region (522) has the first and second points and the second emission region (622) has the third and fourth points. This embodiment enables the extension of the pupil of the image light (L13) in two directions.

[0152] A seventh embodiment is an optical system (3;3A) based on the sixth embodiment. In the seventh embodiment, at least one of the lengths of the first extended region (521) in the first direction (D1), the first exit region (522) in the second direction (D2), the second extended region (621) in the third direction (D3), and the second extended region (621) in the fourth direction (D4) is 100 mm or more. This embodiment can provide the user with a field of view (8) of sufficient size.

[0153] The eighth embodiment is an optical system (3;3A) based on the sixth or seventh embodiment. In the eighth embodiment, the field of view (8) has, in the plane of the field of view (8), a third peripheral region (83) on the third end (8c) side in a second predetermined direction (A2) different from the first predetermined direction (A1), which is the predetermined direction (A1), and a fourth peripheral region (84) on the fourth end (8d) side in the second predetermined direction (A2). The plurality of first division points (P) include fifth points (P21~P24) and sixth points (P41~P44) aligned in the third propagation direction (D2) to divide the first light (L12) propagating in the third propagation direction (D2) corresponding to the second predetermined direction (A2). The fifth points (P21~P24) correspond to points (R21, R22, R23, R24) in the third peripheral region (83). The sixth points (P41-P44) are further from the first coupling region (51) than the fifth points (P21-P24) and correspond to points (R41, R42, R43, R44) within the fourth peripheral region (84). The plurality of second division points (Q) include seventh points (Q21-Q24) and eighth points (Q41-Q44) that are aligned in the fourth propagation direction (D4) to divide the second light (L22) propagating in the fourth propagation direction (D4) corresponding to the second predetermined direction (A2). The seventh points (Q21-Q24) correspond to points (R21, R22, R23, R24) within the third peripheral region (83). The eighth point (Q41~Q44) is further from the second bonding region (61) than the seventh point (Q21~Q24) and corresponds to the points (R41, R42, R43, R44) within the fourth peripheral region (84). If E5 is the division efficiency for the first light (L12) at the fifth point (P21~P24), E6 is the division efficiency for the first light (L12) at the sixth point (P41~P44), E7 is the division efficiency for the second light (L22) at the seventh point (Q21~Q24), and E8 is the division efficiency for the second light (L22) at the eighth point (Q41~Q44), then the division efficiencies E5, E6, E7, and E8 satisfy the following equation (7).

number

[0154] The ninth embodiment is an optical system (3;3A) based on the eighth embodiment. In the ninth embodiment, the division efficiency E6 is greater than the division efficiency E5. The division efficiency E8 is greater than the division efficiency E7. This configuration enables improved uniformity of brightness in a second predetermined direction of the field of view.

[0155] A tenth embodiment is an optical system (3;3A) based on the eighth or ninth embodiment. In the tenth embodiment, the fifth point (P21-P24) and the seventh point (Q21-Q24) correspond to the same points (R21-R24) in the third peripheral region (83). The sixth point (P41-P44) and the eighth point (Q41-Q44) correspond to the same points (R41-R44) in the fourth peripheral region (84). This embodiment enables improved color uniformity.

[0156] The eleventh embodiment is an optical system (3;3A) based on any one of the eighth to tenth embodiments. In the eleventh embodiment, the third peripheral region (83) occupies one-quarter of the field of view region (8) from the third end (8c) of the field of view region (8) in the second predetermined direction (A2). The fourth peripheral region (84) occupies one-quarter of the field of view region (8) from the fourth end (8d) of the field of view region (8) in the second predetermined direction (A2). This embodiment enables improved color uniformity.

[0157] The twelfth embodiment is an optical system (3) based on any one of the first to eleventh embodiments. In the twelfth embodiment, the light guide member (4; 4A) comprises first and second substrates (5, 6) facing each other with an air layer (41) in between. The first bonding region (51) and the first dividing region (52) are provided on the first substrate (5). The second bonding region (61) and the second dividing region (62) are provided on the second substrate (6). This embodiment enables improved color uniformity.

[0158] The thirteenth embodiment is an optical system (3A) based on any one of the first to twelfth embodiments. In the thirteenth embodiment, the light guide member (4A) is composed of a single substrate. This embodiment enables miniaturization of the light guide member (4A).

[0159] The fourteenth embodiment is an optical system (3;3A) based on any one of the first to thirteenth embodiments. In the fourteenth embodiment, the first division region (52) has at least one of a diffraction grating, a volume hologram element, and a half mirror as a structure defining the plurality of first division points (P). The second division region (62) has at least one of a diffraction grating, a volume hologram element, and a half mirror as a structure defining the plurality of second division points (Q). This embodiment enables improved color uniformity.

[0160] The 15th embodiment is an optical system (3;3A) based on any one of the 1st to 14th embodiments. In the 15th embodiment, the first wavelength band is 510 nm to 780 nm. The second wavelength band is 380 nm to 480 nm. This embodiment enables improved color uniformity.

[0161] The sixteenth embodiment is an optical system (3;3A) based on any one of the first to fifteenth embodiments. In the sixteenth embodiment, the refractive index of the light guide member (4;4A) with respect to the d line is greater than 1.7. This embodiment can reduce pupil break of the image light (L1) in the field of view region (8).

[0162] The seventeenth embodiment is an optical system (3;3A) based on any one of the first to sixteenth embodiments. In the seventeenth embodiment, the internal absorption rate of the light guide member (4;4A) for the second light (L21) is greater than 0.05% / mm and less than 0.50% / mm. This embodiment enables improved color uniformity.

[0163] The 18th embodiment is an optical system (3;3A) based on any one of the 1st to 17th embodiments. In the 18th embodiment, the optical system (3;3A) further comprises a projection optical system (7) that causes the image light (L1) to be incident as substantially collimated light on the first coupling region (51) and the second coupling region (61) of the light guide member (4;4A). This embodiment enables improved color uniformity.

[0164] The 19th embodiment is an optical system (3;3A) based on any one of the 1st to 18th embodiments. In the 19th embodiment, a plurality of first emitted light (L13) are parallel to each other. A plurality of second emitted light (L23) are parallel to each other. This embodiment can reduce pupil break of the image light (L1) in the field of view region (8).

[0165] The 20th embodiment is an image display device (1; 1A) comprising an optical system (3; 3A) based on any one of the first to 19 embodiments and the display element (2). This embodiment enables improved color uniformity.

[0166] The above embodiments 2 through 19 are not mandatory.

[0167] As described above, embodiments have been explained as examples of the technology in this disclosure. For this purpose, accompanying drawings and a detailed description have been provided. Accordingly, the components described in the accompanying drawings and detailed description may include not only components essential for solving the problem, but also components that are not essential for solving the problem, in order to illustrate the above technology. Therefore, the mere presence of such non-essential components in the accompanying drawings and detailed description should not be immediately assumed to mean that those non-essential components are essential. Furthermore, since the above embodiments are for illustrative purposes of the technology in this disclosure, various modifications, substitutions, additions, omissions, etc., can be made within the scope of the claims or equivalents thereof. [Industrial applicability]

[0168] This disclosure is applicable to optical systems and image display devices. Specifically, this disclosure is applicable to optical systems for guiding image light from a display element into the user's field of view as a virtual image, and to image display devices equipped with this optical system. [Explanation of symbols]

[0169] 1.1A Image Display Device 2 Display elements 3,3A optical system 4,4A Light guide member 41 Air layer 5. First substrate 51 1st bond area 52 1st divided area 521 First Expansion Area 522 1st output area 6. Second board 61 2nd bond area 62 Second divided area 621 Second Expansion Area 622 2nd output area 7 Projection optical system 8 field of view 8a 1st end 8b 2nd end 8c 3rd end 8d 4th end 81 First Peripheral Region 82 Second Peripheral Area 83 Third Peripheral Area 84. Fourth Peripheral Area L1 Image Light L11,L12 1st light L13 1st output light (1st light) L21,L22 2nd light L23 2nd output light (2nd light) P11~P14,P21~P24,P31~P34,P41~P44 1st division point Q11~Q14,Q21~Q24,Q31~Q34,Q41~Q44 2nd division point R21~R24, R31~R34, R41~R44 points D1 First direction (first propagation direction) D2 Second direction (third propagation direction) D3 Third direction (second propagation direction) D4 Fourth direction (fourth propagation direction)

Claims

1. It includes a light guide member that guides the image light that forms the image output from the display element into the user's field of view as a virtual image, The image light includes a first light in a first wavelength band and a second light in a second wavelength band with a shorter wavelength than the first wavelength band. The light guide member is A first coupling region that causes the first light to be incident into the light guide member so that the first light propagates within the light guide member, A first dividing region having a plurality of first dividing points that divide the first light incident into the light guide member from the first coupling region, and emitting a plurality of first emitted light to the field of view region, A second coupling region that causes the second light to be incident into the light guide member so that the second light propagates within the light guide member, A second dividing region having a plurality of second dividing points that divide the second light incident into the light guide member from the second coupling region, and emitting a plurality of second emitted light to the field of view region, It has, The field of view region comprises a first peripheral region at the first end in a predetermined direction within the plane of the field of view region, and a second peripheral region at the second end in the predetermined direction. The plurality of first division points include a first point and a second point aligned in the first propagation direction so as to divide the first light propagating in the first propagation direction corresponding to the predetermined direction, The first point corresponds to a point within the first peripheral region, The second point is further from the first bonding region than the first point, and corresponds to a point within the second peripheral region. The plurality of second division points include third and fourth points aligned in the second propagation direction so as to divide the second light propagating in the second propagation direction corresponding to the predetermined direction, The third point corresponds to a point within the first peripheral region, The fourth point is further from the second bonding region than the third point, and corresponds to a point within the second peripheral region. If we denote the division efficiency for the first light at the first point as E1, the division efficiency for the first light at the second point as E2, the division efficiency for the second light at the third point as E3, and the division efficiency for the second light at the fourth point as E4, The division efficiencies E1, E2, E3, and E4 are, [Math 1] Satisfying optical system.

2. In the aforementioned image light, the amount of light of the second light is greater than the amount of light of the first light. The optical system according to claim 1.

3. The aforementioned division efficiency E2 is greater than the aforementioned division efficiency E1. The division efficiency E4 is greater than the division efficiency E3. The optical system according to claim 1 or 2.

4. The first and third points correspond to the same points within the first peripheral region, The second and fourth points correspond to the same points in the second peripheral region, The optical system according to claim 1 or 2.

5. The first peripheral region occupies 1 / 4 of the field of view from the first end of the field of view in the predetermined direction. The second peripheral region occupies 1 / 4 of the field of view from the second end of the field of view in the predetermined direction. The optical system according to claim 1 or 2.

6. The first divided region comprises a first extended region and a first ejection region. The first extended region directs a plurality of first beams of light, arranged in a first direction perpendicular to the thickness direction of the light guide member, toward the first emission region by splitting the first beam of light propagating within the light guide member. The first emission region emits multiple first light beams into the field of view area as multiple first emitted light beams by splitting the multiple first light beams from the first extended region, and aligning them in a second direction that is perpendicular to the thickness direction of the light guide member and intersects the first direction. The aforementioned second divided region has a second extended region and a second ejection region, The second extended region directs a plurality of second beams of light, arranged in a third direction corresponding to the first direction, toward the second emission region by splitting the second beam of light propagating within the light guide member. The second emission region emits multiple second beams of light, arranged in a fourth direction corresponding to the second direction, into the field of view region by splitting the multiple second beams of light from the second extended region, as the multiple second emitted beams. The first expansion region has the first point and the second point and the second expansion region has the third point and the fourth point, or the first ejection region has the first point and the second point and the second ejection region has the third point and the fourth point, The optical system according to claim 1 or 2.

7. At least one of the lengths of the first expansion region in the first direction, the first emission region in the second direction, the second expansion region in the third direction, and the second expansion region in the fourth direction is 100 mm or more. The optical system according to claim 6.

8. The field of view region has, within the plane of the field of view region, a third peripheral region on the third end side in a second predetermined direction that intersects with the first predetermined direction which is the predetermined direction, and a fourth peripheral region on the fourth end side in the second predetermined direction. The plurality of first division points include fifth and sixth points aligned in the third propagation direction so as to divide the first light propagating in the third propagation direction corresponding to the second predetermined direction, The fifth point corresponds to a point within the third peripheral region, The sixth point is further from the first bonding region than the fifth point, and corresponds to a point within the fourth peripheral region. The plurality of second division points include seventh and eighth points aligned in the fourth propagation direction so as to divide the second light propagating in the fourth propagation direction corresponding to the second predetermined direction, The seventh point corresponds to a point within the third peripheral region, The eighth point is further from the second bonding region than the seventh point, and corresponds to a point within the fourth peripheral region. If we denote the division efficiency for the first light at the fifth point as E5, the division efficiency for the first light at the sixth point as E6, the division efficiency for the second light at the seventh point as E7, and the division efficiency for the second light at the eighth point as E8, The division efficiencies E5, E6, E7, and E8 are, [Math 2] Satisfying the conditions, The first extended region has the first point and the second point, and the second extended region has the third point and the fourth point, The first ejection region has the fifth and sixth points, and the second ejection region has the seventh and eighth points, The optical system according to claim 6.

9. The aforementioned division efficiency E6 is greater than the aforementioned division efficiency E5. The division efficiency E8 is greater than the division efficiency E7. The optical system according to claim 8.

10. The fifth and seventh points correspond to the same points within the third peripheral region, The sixth and eighth points correspond to the same points in the fourth peripheral region, The optical system according to claim 8.

11. The third peripheral region occupies 1 / 4 of the field of view from the third end of the field of view in the second predetermined direction. The fourth peripheral region occupies 1 / 4 of the field of view from the fourth end of the field of view in the second predetermined direction. The optical system according to claim 8.

12. The light guide member comprises a first and second substrate facing each other with an air layer in between, The first bonding region and the first dividing region are provided on the first substrate. The second bonding region and the second dividing region are provided on the second substrate. The optical system according to claim 1 or 2.

13. The light guide member is composed of a single substrate. The optical system according to claim 1 or 2.

14. The first divided region has at least one of a diffraction grating, a volume hologram element, and a half mirror as a structure that defines the plurality of first divided points. The second division region has at least one of a diffraction grating, a volume hologram element, and a half mirror as a structure that defines the plurality of second division points. The optical system according to claim 1 or 2.

15. The first wavelength band is 510 nm to 780 nm. The second wavelength band is between 380 nm and 480 nm. The optical system according to claim 1 or 2.

16. The refractive index of the light guide member with respect to the d line is greater than 1.

7. The optical system according to claim 1 or 2.

17. The internal absorption rate of the light guide member for the second light is greater than 0.05% / mm and less than 0.50% / mm. The optical system according to claim 1 or 2.

18. The system further includes a projection optical system that causes the aforementioned image light to be incident on the first and second coupling regions of the light guide member as substantially collimated light. The optical system according to claim 1 or 2.

19. The plurality of first emitted light rays are parallel to each other, The plurality of second emitted light rays are parallel to each other. The optical system according to claim 1 or 2.

20. The optical system according to claim 1 or 2, The aforementioned display button, Equipped with, Image display device.

Images