Propagation optical system, virtual image display device, and head-mounted display

Abstract

To achieve a novel propagation optical system that is used for a light guide type virtual image display device and propagates an image displayed on an image display element to a light guide member.SOLUTION: A propagation optical system is used for a virtual image display device that causes a light guide member 30 to guide light from an image display element 10 on which an image is displayed and to emit the light from the light guide member to the outside to display a virtual image of the image, and propagates the light from the image display element to the light guide member. The propagation optical system has a first optical system RL, an intermediate optical element LI, and a second optical system LC arranged in order from the side of the image display element toward the side of the light guide member, and forms an intermediate image IN of the image displayed on the image display element between the first optical system and the second optical system. The intermediate optical element LI has a non-rotationally symmetrical curved surface that is non-rotationally symmetrical with respect to an optical axis, and of a cross section of the non-rotationally symmetrical curved surface including the optical axis, a specific cross section being a cross section having the strongest positive power has a non-arcuate cross-sectional shape.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a propagation optical system, a virtual image display device, and a head mounted display. [Background technology]

[0002] 2. Description of the Related Art Virtual image display devices, which enlarge a two-dimensional image by a virtual image optical system and display the enlarged virtual image for an observer to observe, have recently become widespread as HMDs (head mounted displays). HMDs are broadly divided into see-through and non-see-through types, and see-through types are used in combination with information terminals or AR (Augmented Reality), and recently, what are called "smart glasses" have been attracting attention. Non-see-through types are used in games and VR (Virtual Reality), and are widely loved because they provide a high level of immersion.

[0003] One type of virtual image display device known is one in which an "image to be displayed as a virtual image" is displayed on an image display element, the displayed image is propagated as image information to a light guide member through a propagation optical system, the propagated image information is guided by the light guide member, and is emitted as reflected light toward an observer, so that the observer observes an enlarged virtual image (hereinafter, for convenience, referred to as a "light guide type" (Patent Documents 1 and 2). The above-mentioned smart glasses are also of the light guide type. Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to realize a novel propagation optical system that is used in the light-guiding type virtual image display device and propagates an image displayed on an image display element to a light-guiding member. [Means for solving the problem]

[0005] The propagation optical system of the present invention includes a light guide member, a light display element, and a light guide member. The light is guided to the front The light is emitted to the outside from the light guide member. ByA propagation optical system is used in a virtual image display device that displays a virtual image of the image, and propagates light from the image display element to the light guiding member, and includes a first optical system, an intermediate optical element, and a second optical system arranged in this order from the image display element side to the light guiding member side, and an intermediate image of the image displayed on the image display element is formed between the first optical system and the second optical system, and the intermediate optical element has a non-rotationally symmetric curved surface that is shaped as non-rotationally symmetric with respect to an optical axis, and a cross-sectional shape of a specific cross section that is a cross section having the strongest positive power among cross sections including the optical axis of the non-rotationally symmetric curved surface is a non-arc shape. The rotationally asymmetric curved surface of the intermediate optical element is an anamorphic aspheric surface. do. Effect of the Invention

[0006] According to the present invention, it is possible to realize a novel propagation optical system that is used in a light-guiding type virtual image display device and propagates an image displayed on an image display element to a light-guiding member. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a conceptual diagram illustrating a virtual image display device. [Diagram 2] 1 is a diagram illustrating a configuration of a propagation optical system according to a first embodiment. [Diagram 3] FIG. 11 is a diagram illustrating a configuration of a propagation optical system according to a second embodiment. [Figure 4] FIG. 11 is a diagram illustrating a configuration of a propagation optical system according to a third embodiment. [Diagram 5] FIG. 13 is a diagram illustrating a configuration of a propagation optical system according to a fourth embodiment. [Figure 6] FIG. 13 is a diagram illustrating a configuration of a propagation optical system according to a fifth embodiment. [Figure 7] 1A and 1B are diagrams for explaining positions on a virtual image in a propagation optical system according to an embodiment. [Figure 8] 4A to 4C are diagrams showing lateral aberration of the propagation optical system of the first embodiment. [Figure 9] 11A to 11C are diagrams showing lateral aberration of the propagation optical system of the second embodiment. [Figure 10] 11A to 11C are diagrams showing lateral aberration of the propagation optical system of the third embodiment. [Figure 11] 11A to 11C are lateral aberration diagrams of the propagation optical system of Example 4. [Figure 12] 13A to 13C are diagrams showing lateral aberration of the propagation optical system of the fifth embodiment. [Figure 13] FIG. 13 is a diagram illustrating a configuration of a propagation optical system according to a sixth embodiment. [Figure 14] FIG. 13 is a diagram illustrating a configuration of a propagation optical system according to a seventh embodiment. [Figure 15] FIG. 13 is a diagram showing the configuration of a propagation optical system according to an eighth embodiment. [Figure 16] FIG. 13 is a diagram showing the configuration of a propagation optical system according to a ninth embodiment. [Figure 17] 13A to 13C are diagrams showing lateral aberration of the propagation optical system of Example 6. [Figure 18] 13 is a lateral aberration diagram of the propagation optical system of Example 7. FIG. [Figure 19] 13A to 13C are diagrams showing lateral aberration of the propagation optical system of Example 8. [Figure 20] 13A to 13C are lateral aberration diagrams of the propagation optical system of Example 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Please refer to Figure 1. Fig. 1 is an explanatory diagram of a virtual image display device using a propagation optical system according to the present invention, illustrating a state in which the virtual image display device is worn by an observer as an HMD. In Fig. 1, the symbol EY denotes the observer's eyes. If the x, y, and z directions are defined as in FIG. 1, the y direction (the direction perpendicular to the plane of the drawing in FIG. 1(a)) corresponds to the up-down direction in the normal wearing state. In FIG. 1, reference numeral 10 denotes an "image display element," reference numeral 20 denotes a "propagation optical system," and reference numeral 30 denotes a "light guiding member." An "image display element" is an element that displays an image to be observed as a virtual image, and an OLED (organic LED) array is suitable, but other elements such as an LD array, an LED array, or a DMD (digital micromirror device) can also be used. For the sake of concreteness, taking an OLED array as an example of an image display element, the size of the image display area (pixel array area) is, for example, 3 mm×4 mm, and the number of pixels is about 10,000.

[0009] When pixels corresponding to an image to be displayed are illuminated, an “image” is displayed in the image display area. Light from the displayed image enters the propagation optical system 20. The propagation optical system 20 of the present invention includes, in order from the image display element 10 side toward the light guide member 30 side, a first optical system RL, an intermediate optical element LI, and a second optical element LC. In the following description, the first optical system is referred to as a "relay optical system" and the second optical system is referred to as a "collimator optical system."

[0010] Light incident on the propagation optical system 20 from the image display element 10 forms an intermediate image IN of the image displayed on the image display element 10 between the first optical system, the relay optical system RL, and the second optical system, the collimator optical system LC. In FIG. 1, the intermediate image IN is formed between the intermediate optical element LI and the collimator optical system LC. However, the intermediate image IN may be formed between the relay optical system RL, which is the first optical system, and the intermediate optical element LI, or may be formed between the intermediate optical element LI and the relay optical system RL. In some cases, the image may be formed inside the LI. The intermediate image IN is an "object" for the virtual image observed by the observer. That is, the observer observes an enlarged virtual image formed behind the image display element 10 by the action of a second optical system (collimator optical system LC in the illustrated example) between the intermediate image LN and the light guiding member 30, through the light guiding member 30.

[0011] As shown in FIG. 1(a), the light guide member 30 is plate-shaped when viewed from the y direction, and the portion on the right side of the figure narrows in a wedge shape to form an observation light extraction portion 30B. When light from the propagation optical system 20 enters the light-guiding member 30 from the entrance portion 30A of the light-guiding member 30, the incident light becomes a guided light beam LP within the light-guiding member 30 and is guided toward the observation light extraction portion 30B while repeatedly reflecting on "surfaces that are parallel to each other in the z direction." The size of the incident portion 30A of the light guide member 30 is "approximately the same as the thickness of the light guide member" when viewed in the y direction, and is, for example, 2 to 3 mm. When viewed from the z - direction, the light - guiding member 30 has a rectangular shape as shown in Fig. 1(b), and the light - guiding light beam LP has a large width in the y - direction. The size of the light - guiding member 30 in the y - direction is about 20 - 30 mm. In the light - guiding member 30, in the part of the observation - light extraction portion 30B that is the "upper side in the z - direction" in Fig. 1(a), as shown in Fig. 1(b), narrow - width and strip - shaped planar portions 301 and planar portions 302 are arranged alternately. The planar portion 301 slopes downward to the right direction (x - direction) of Fig. 1(a) with a predetermined inclination angle, and the planar portion 302 is parallel to the xy plane. In this way, the planar portion 302 descends step - by - step, and together with the planar portion 301, it forms a "surface that narrows in a wedge - shape" toward the part of the observation - light extraction portion 30B that is the "lower side in the z - direction" in Fig. 1(a) as shown in Fig. 1(a). In the observation - light extraction portion 30B, the light - guiding light beam LP is reflected by the planar portion 301 with an inclination angle and is emitted as the observation - use image light LT toward the observer's eye EY. When this observation - use emitted light is incident on the eye EY, it forms an image on the retina as a "conjugate image of a virtual image", and the observer will see an enlarged virtual image of the image in the z - direction.

[0012] The relay optical system RL and the collimator optical system LC constituting the propagation optical system 20 are rotationally symmetric with respect to the optical axis and have positive power. The intermediate optical element LI has a "non - rotationally symmetric curved surface with a non - rotationally symmetric shape" with respect to the optical axis (the optical axis shared by the relay optical system RL and the collimator optical system LC). For this non - rotationally symmetric curved surface, the "cross - section that has the strongest positive power among the cross - sections including the optical axis" is called the "specific cross - section". The "cross - section shape of the specific cross - section" is a non - circular - arc shape.

[0013] In order to reduce the lens diameter of the collimator lens LC while ensuring a certain optical overall length while having high performance, it is good for the propagation optical system to "form an intermediate image". The diameter of the relay optical system RL can be made relatively small. By having the relay optical system RL, it is possible to cope even when it is necessary to ensure the "distance between the image display element and the propagation optical system" due to mechanical or electrical system reasons. As described above, the propagation optical system 20 is configured by arranging, in this order from the image display element 10 side, the relay optical system RL, the intermediate optical element LI, and the collimator optical system LC. Since the intermediate image IN is formed between the relay optical system RL and the collimator optical system LC, the position of the “non-rotationally symmetric curved surface” of the intermediate optical element LI is close to the intermediate image IN, making it possible to reduce spherical aberration and coma aberration caused by non-rotational symmetry.

[0014] The "specific cross section" should preferably correspond to the horizontal direction of the displayed virtual image (x direction in FIG. 1). In this way, in the specific cross section with the strongest positive power, the off-axis chief rays of the propagation optical system 20 can be made to enter the light so as to intersect with the optical axis near the entrance part 30A of the light-guiding member 30, and the light can be efficiently propagated to the eye EY. In particular, even if the opening width in the direction corresponding to the specific cross section of the incident portion 30A of the light-guiding member 30 (the opening width in the yz plane) is small, the loss of the principal light beam due to the incident portion 30A can be reduced and the light utilization efficiency can be improved. In other words, even if the light-guiding member 30 is made thin (reduced in size and weight), the loss of the principal light beam can be reduced.

[0015] It is preferable that the "non-arc shape" of the specific cross section is a "shape in which the positive power decreases as the distance from the optical axis increases." In this way, each off-axis chief ray of the propagation optical system 20 can intersect with the optical axis at a position closer to the entrance part 30A, and the light can be more efficiently "propagated to the eye EY."

[0016] The above "shape in which the positive power weakens as it moves away from the optical axis" is a shape in which the maximum value of the "difference in the sag between the non-circular shape of a specific cross section and the arc of the paraxial curvature circle of the non-circular shape" (Sag) and the effective ray height (H) from the optical axis (H) are satisfied under the following conditions: (1) 0.02 < Sag / H < 0.25 It is preferable that the shape satisfies the above. The "sign of the amount of sag" is positive in the direction in which the positive power of the non-arc shape becomes weaker. If the upper limit of condition (1) is exceeded, the amount of asphericity becomes too large, and the "correction by the asphericity" tends to be excessive, whereas if the lower limit is exceeded, the correction tends to be insufficient. Therefore, whether the upper limit or the lower limit is exceeded, it tends to be difficult to effectively increase the efficiency of light transmission to the eye EY. It is more preferable that the parameter Sag / H of the condition (1) satisfies the following condition (1A):

[0017] In the following, the condition (1) etc. will also be referred to as "conditional formula (1)" etc.

[0018] (1A) 0.05 < Sag / H < 0.20 In addition, the relay optical system can be configured by arranging, in order from the image display element side to the intermediate optical element side, a first front group (hereinafter referred to as the ``relay pre-group'') and a first rear group (hereinafter referred to as the ``relay rear group''), both of which have positive power, so that the distance between the relay pre-group and the relay rear group is ``the widest in all relay optical systems.'' By doing so, it is possible to ensure an appropriate distance between the pre-relay group and the post-relay group, and to ensure the overall length of the propagation optical system, while at the same time making good correction for various aberrations. In this case, the thickness of the relay optical system: TLR, and the distance between the pre-relay group and the post-relay group: TLRa are as follows: (2) 0.4< TLRa / TLR <0.7 It is preferable to satisfy the following: If the upper limit of condition (2) is exceeded, the ratio of the spacing between the pre-relay group and the post-relay group to the thickness of the relay optical system becomes too large, the space required for the pre-relay group and the post-relay group becomes too small, and it becomes difficult to correct various aberrations in the relay optical system.If the lower limit is exceeded, the spacing between the pre-relay group and the post-relay group becomes too small, and it becomes difficult to satisfactorily correct various aberrations in the relay optical system while ensuring the overall length of the propagation optical system. When the relay optical system is constructed as described above using the pre-relay group and the post-relay group, it is preferable that the pre-relay group be constructed by arranging, in order from the image display element side to the intermediate optical element side, a positive lens, a negative lens, and a positive lens. By configuring the front relay group in this manner, it is possible to sufficiently correct chromatic aberration while in particular spherical aberration, coma, etc. It is desirable that the lens surfaces of the positive lens, negative lens, and positive lens be aspherical.

[0019] The rear relay group can be constructed by arranging, in order from the image display element side to the intermediate optical element side, a positive lens and a negative lens. With this configuration, residual aberrations in the pre-relay group and collimator optical system are corrected by two lenses, one positive and one negative, making it easy to sufficiently correct various aberrations. When the post-relay group is composed of a positive lens and a negative lens, it is preferable that the lens surfaces of the two lenses are aspheric.

[0020] In the above configuration, the distance from the non-rotationally symmetric curved surface of the intermediate optical element to the surface of the collimator optical system closest to the light guiding member: TLA, and the distance from the surface of the relay optical system closest to the image display element to the surface of the collimator optical system closest to the light guiding member: TL are set to satisfy the following conditions: (3) 0.1< TLA / TL <0.5 It is preferable to satisfy the following. The "spacing" is, of course, a value on the optical axis. If the upper limit of condition (3) is exceeded, the distance between the non-rotationally symmetric curved surface and the light-guiding member becomes too large, and the diameter of the intermediate optical element having the non-rotationally symmetric curved surface and the collimator optical system tends to become too large, whereas if the lower limit is exceeded, the distance between the non-rotationally symmetric curved surface and the light-guiding member becomes too small, the effect of the non-rotationally symmetric curved surface becomes small, and the incidence range on the light-guiding member tends to become too large. By satisfying condition (4), it is possible to further miniaturize the propagation optical system.

[0021] In the above configuration, the thickness of the collimator optical system: TLC and the thickness of the relay optical system: TLR are set under the following conditions: (4) 0.3< TLC / TLR <0.6 It is preferable to satisfy the following: If the upper limit of the condition (4) is exceeded, the collimator optical system becomes thick, and the diameters of the intermediate optical element having a rotationally asymmetric curved surface and the collimator optical system tend to become excessively large, whereas if the lower limit is exceeded, the collimator optical system becomes thin, and it tends to become difficult to correct various aberrations in the collimator optical system.

[0022] The propagation optical system of the present invention also satisfies the following condition: (5) -3.0< β_relay <-1.0 It is preferable to satisfy the following: When the image display area of ​​the image display element becomes large, electrical system components such as PCBs also become large, which tends to make miniaturization difficult. To widen the angle of view, the intermediate image needs to be relatively large. From this viewpoint, the condition (5) prescribes a suitable range for the lateral magnification: β_relay of the relay optical system.

[0023] The "non-rotationally symmetric curved surface" of the intermediate optical element can be, for example, a "toroidal surface" or a "cylindrical surface", and the intermediate optical element can be a "toroidal lens" or a "cylindrical lens". In this case, the cylindrical lens as the intermediate optical element has a power of 0 in the direction of the no curvature of the non-rotationally symmetric curved surface, which is the "second specific cross section, which is the cross section with the weakest positive power," and the curved surface shape in the cross section perpendicular to this direction is the "non-arcuate shape of the specific cross section." Such a cylindrical lens is easier to process than a free-form surface lens such as a toroidal lens, and the processing costs can be reduced.

[0024] In the above configuration, by further satisfying the following conditions (6) and (7), it is possible to achieve even higher performance of the propagation optical system. (6) -0.5< Pos1 / Y <0.5 In condition (6), "Pos1" is the position on the optical axis of a non-rotationally symmetric surface. Distance from the intermediate image positionand it is considered negative when the rotationally asymmetric surface is on the "image display element side from the position of the intermediate image." "Y" is the diagonal length of the image display area of ​​the image display element. If either the upper or lower limit is exceeded, the distance between the non-rotationally symmetric curved surface and the intermediate image becomes large, and it tends to become difficult to suppress the occurrence of non-rotationally symmetric spherical aberration and coma aberration.

[0025] It is preferable that the propagation optical system also satisfies the following condition (7):

[0026] (7) 0.4< f_r / f_rf <0.8 "f_r" is the focal length of the relay optical system (>0), and "f_rf" is the focal length of the pre-relay group. The pre-relay group has the main image-forming function within the relay optical system, and it is important to have an appropriate power arrangement for the relay optical system. If the upper limit of condition (7) is exceeded, the focal length of the pre-relay group will be short, and if the lower limit is exceeded, the focal length of the pre-relay group will be long, and in either case, it tends to become difficult to sufficiently correct "the aberrations occurring in the pre-relay group."

[0027] By using the propagation optical system described above as the propagation optical system 20 in Figure 1, it is possible to realize a virtual image display device in which light from the image display element 10 displaying an image is propagated by the propagation optical system 20 to the light-guiding member 30, guided through the light-guiding member 30, and emitted to the outside from the light-guiding member 30, thereby displaying a virtual image of the image using the emitted light.

[0028] Moreover, the virtual image display device described with reference to FIG. 1 is an HMD, and therefore can be configured as a "glasses type" device like the above-mentioned "smart glasses."

[0029] Below are nine specific examples of propagation optical systems. 2 to 6 show five examples of lens configurations of the propagation optical system in sequence. 2 to 6, the X and Y directions are defined as follows. The Y direction (hereinafter also referred to as the "vertical direction") corresponds to the longitudinal direction of the image display area of ​​the image display element 10. The X direction (hereinafter also referred to as the "horizontal direction") corresponds to the lateral direction of the image display area. It should be noted that the Y direction is a "direction" and is different from the "diagonal length of the image display area of ​​the image display element" described above.

[0030] In the virtual image display devices according to Examples 1 to 5 described below, the size of the image display area is 3.12 mm in the Y direction (vertical direction) and 4.992 mm in the X direction (horizontal direction), with a diagonal length of 5.89 mm. Moreover, the size of the image display area in the propagation optical system in Example 4 is 2.97 mm in the Y direction (vertical direction), 5.28 mm in the X direction (horizontal direction), and the diagonal length is 6.06 mm. That is, in the virtual image display device shown in Fig. 1, the virtual image observed by the observer through the light guiding member 30 is a "horizontally elongated image" and is observed as a plane parallel to the xy plane in Fig. 1(a). Therefore, in correspondence with this virtual image, the longitudinal direction of the image display area is set to the horizontal direction (i.e., the "X direction"), and the lateral direction is set to the vertical direction (i.e., the "Y direction"). The direction perpendicular to the X and Y directions is defined as the Z direction, which coincides with the optical axis direction of the propagation optical system in FIGS. 2 to 6, (a) shows the "cross-sectional shape in the YZ plane" of the propagation optical system, and (b) shows the "cross-sectional shape in the XZ plane" of the propagation optical system. The left side of the figure is the object side. That is, in these figures, the up and down direction in (a) is the Y direction (vertical direction), and the up and down direction in (b) is the X direction (horizontal direction).

[0031] To avoid complexity, the same reference numerals are used in FIGS. That is, by using the symbols in FIG. 1, the image display surface that matches the image display area of ​​the image display element is denoted by the symbol The image display surface is denoted by reference numeral 10 (FIG. 5), a "cover glass" provided on the image display surface is denoted by reference numeral 11, a relay optical system is denoted by reference numeral RL, and a collimator optical system is denoted by reference numeral LC. The intermediate optical element is designated by the symbol LI, the symbol RL1 denotes the "pre-relay group," and the symbol RL2 denotes the "post-relay group." Also, the symbol S denotes the "aperture stop." In all of the examples of Figures 2 to 6, the propagation optical system is composed of a relay optical system RL, an intermediate optical element LI, and a collimator optical system LC arranged in that order from the image display element side (left side of the figure) to the light-guiding member (not shown) side (right side of the figure), and the relay optical system RL is made up of a pre-relay group RL1 and a post-relay group RL2. In each example, the pre-relay group RL1 is composed of three lenses, positive, negative, and positive, in that order from the image display element side, and the post-relay group RL2 is composed of two lenses, positive and negative, in the same order. The collimator optical system LC is composed of two lenses, negative and positive, in the same order.

[0032] The lenses that make up the pre-relay group RL1, the post-relay group RL2, and the collimator optical system LC are rotationally symmetrical about the optical axis (Z direction), and the pre-relay group RL1, the post-relay group RL2, and the collimator optical system LC, which are arranged in the optical axis direction (Z direction), are also rotationally symmetrical about the optical axis. The relay optical system RL and the pre-relay lens unit RL1 and the post-relay lens unit RL2 that constitute the relay optical system RL all have positive power, and the collimator optical system LC also has positive power. The intermediate optical element LI has no power in the YZ plane and positive power in the XZ plane.

[0033] That is, the intermediate optical element LI in the propagation optical system in FIGS. 2 to 6 is a "cylindrical lens" whose surface on the image display element side (the relay optical system RL side) is a cylindrical surface and whose surface on the collimator optical system LC side is a flat surface. The cylindrical surface is a "non-rotationally symmetric curved surface having a shape that is non-rotationally symmetric with respect to the optical axis," and the "specific cross section," which is the cross section including the optical axis of the non-rotationally symmetric curved surface and has the strongest positive power, is the XZ plane (the horizontal plane including the optical axis) as shown in Figures 2 to 6(b), and its shape is a non-circular arc shape.

[0034] Below, five specific examples of the virtual image display device using the propagation optical system shown in Figures 2 to 6 will be given. The meanings of symbols in Examples 1 to 5 are as follows. Rx: Radius of curvature in the XZ plane Ry: Radius of curvature in the YZ plane D: Surface spacing N d : Refractive index ν d :Abbe number The aspheric amount of an aspheric surface: ξ is expressed as C, h, K, A, and A. 4 , A 6 , A 8 , A 10 is expressed by the well-known formula (A) below. ξ = Ch 2 / {1+√(1-(1+K)C 2 h 2 )} +A 4 h 4 +A 6 h 6 +A 8 h 8 +A 10 h 10 (A)

[0035] In the following descriptions, the unit of "quantities having the dimension of length" is "mm" unless otherwise specified. Furthermore, in the following Examples 1 to 5, the light-guiding member is different from that described in FIG. 1 in that it is a parallel plate as a whole, and the portion corresponding to the observation light extraction section 30B in the example shown in FIG. 1 is composed of multiple semi-transparent surfaces inclined in the X direction.

[0036] "Example 1" The first embodiment is an embodiment that uses a propagation optical system having the lens configuration shown in FIG. The "angle of view" of the propagation optical system is as follows for the vertical direction (Y direction), horizontal direction (X direction), and diagonal direction. Angle of view: Vertical: 17.9 degrees Horizontal: 35.5 degrees Diagonal: 40.0 degrees Also, the virtual image distance is 1m. The data for Example 1 is shown in Table 1.

[0037] [Table 1]

[0038] In Table 1, the leftmost column is "Surface Number," which shows the sequential surface numbers from the image display element side, including the "aperture" surface. Surfaces marked with an "*" in the surface number column are "aspheric surfaces." The rightmost column lists the product names of the materials of the lenses, etc., along with their manufacturers. This labeling format is the same in Examples 2 to 5, which will be described in turn below. In FIG. 2 showing Example 1, reference numeral 11 denotes a cover glass provided in close contact with the “image display surface corresponding to the image display area” of the image display element, and in Table 1, surface number: 0 denotes the image display surface, and surface numbers: 1 and 2 denote both sides of the cover glass. Surface numbers 3 to 13 indicate a relay optical system RL, and surface numbers 3 to 8 on the image display element side of the stop surface number 9 indicate a front relay group RL1, and surface numbers 10 to 13 indicate a rear relay group RL2.

[0039] Surface numbers 14 and 15 indicate an intermediate optical element LI. The intermediate optical element LI is a cylindrical lens, and the surface facing the image display element is an aspheric cylindrical lens surface, and Rx of surface number 14 is the “paraxial curvature” of the non-circular arc shape in a specific cross section. Surface numbers 16 to 19 indicate the collimator optical system LC, surface numbers 20 and 21 indicate parallel plate-like light guiding members, and the surface distance between surface numbers 20 and 21 is a value converted according to the number of reflections within the light guiding member. The distance from surface 21 to the observer's eye is the "eye relief" and is 15 mm.

[0040] "Aspheric data" Table 2 shows the aspheric surface data for the aspheric surfaces (Table 1) marked with an "*" (except for surface number 14).

[0041] [Table 2]

[0042] In the notation in Table 2, for example, "-2.61811E-04" is "-2.61811 x 10 -4 " The same applies below.

[0043] Table 3 shows the aspheric surface data in the XZ plane of surface number 14, which is the “specific cross section.”

[0044] [Table 3]

[0045] "Parameter value of the conditional expression" Table 4 shows the values ​​of conditional expressions (1) to (7) for the propagation optical system in Example 1.

[0046] [Table 4]

[0047] The value of "H" in the parameter of conditional formula (1) in Table 4 is "H=6.0 mm."

[0048] "Example 2" The second embodiment is an embodiment that uses a propagation optical system having the lens configuration shown in FIG. The "angle of view" of the propagation optical system is as follows for the vertical direction (Y direction), horizontal direction (X direction), and diagonal direction. Angle of view: Vertical: 18.1 degrees Horizontal: 35.4 degrees Diagonal: 39.8 degrees Also, the virtual image distance is 1m. The data for Example 2 is shown in Table 5.

[0049] [Table 5]

[0050] In FIG. 3 showing Example 2, reference numeral 11 denotes a cover glass provided in close contact with the image display surface of the image display element, and in Table 5, surface number: 0 denotes the image display surface, and surface numbers: 1 and 2 denote both sides of the cover glass. Surface numbers 3 to 13 indicate a relay optical system RL, and surface numbers 3 to 8 on the image display element side of the stop surface number 9 indicate a front relay group RL1, and surface numbers 10 to 13 indicate a rear relay group RL2.

[0051] Surface numbers 14 and 15 indicate an intermediate optical element LI. The intermediate optical element LI is a cylindrical lens, and the surface facing the image display element is an aspheric cylindrical lens surface, and Rx of surface number 14 is the “paraxial curvature” of the non-circular arc shape in a specific cross section. Surface numbers 16 to 19 indicate the collimator optical system LC, surface numbers 20 and 21 indicate parallel plate-like light guiding members, and the surface distance between surface numbers 20 and 21 is a value converted according to the number of reflections within the light guiding member. The distance from surface 21 to the observer's eye is the "eye relief" and is 15 mm.

[0052] "Aspheric data" The aspheric data of the aspheric surfaces is shown in Table 6 following Table 2.

[0053] [Table 6]

[0054] Table 7 shows the aspheric surface data in the XZ plane of surface number 14, which is the “specific cross section”.

[0055] [Table 7]

[0056] "Parameter value of the conditional expression" Table 8 shows the values ​​of conditional expressions (1) to (7) of the propagation optical system of the second embodiment.

[0057] [Table 8]

[0058] The parameter "H" in conditional formula (1) is "H=6.0 mm."

[0059] "Example 3" The third embodiment is an embodiment that uses a propagation optical system having the lens configuration shown in FIG. The "angle of view" of the propagation optical system is as follows for the vertical direction (Y direction), horizontal direction (X direction), and diagonal direction. Angle of view: Vertical: 18.1 degrees Horizontal: 35.9 degrees Diagonal: 40.1 degrees Also, the virtual image distance is 1m. The data for Example 3 is shown in Table 9.

[0060] [Table 9]

[0061] In FIG. 4 showing Example 3, reference numeral 11 denotes a cover glass provided in close contact with the image display surface of the image display element, and in Table 9, surface number: 0 denotes the image display surface, and surface numbers: 1 and 2 denote both sides of the cover glass. Surface numbers 3 to 13 indicate a relay optical system RL, and surface numbers 3 to 8 on the image display element side of the stop surface number 9 indicate a front relay group RL1, and surface numbers 10 to 13 indicate a rear relay group RL2.

[0062] Surface numbers 14 and 15 indicate an intermediate optical element LI. The intermediate optical element LI is a cylindrical lens, and the surface facing the image display element is an aspheric cylindrical lens surface, and Rx of surface number 14 is the “paraxial curvature” of the non-circular arc shape in a specific cross section.

[0063] Surface numbers 16 to 19 indicate the collimator optical system LC, surface numbers 20 and 21 indicate parallel plate-like light guiding members, and the surface distance between surface numbers 20 and 21 is a value converted according to the number of reflections within the light guiding member. The distance from surface 21 to the observer's eye is the "eye relief" and is 15 mm.

[0064] "Aspheric data" The aspheric data of the aspheric surfaces is shown in Table 10 following Table 2.

[0065] [Table 10]

[0066] Table 11 shows the aspheric surface data in the XZ plane of surface number 14, which is the “specific cross section”.

[0067] [Table 11]

[0068] "Parameter value of the conditional expression" Table 12 shows the values ​​of conditional expressions (1) to (7) of the propagation optical system of Example 3.

[0069] [Table 12]

[0070] The parameter "H" in conditional formula (1) is "H=6.0 mm."

[0071] "Example 4" The fourth embodiment is an embodiment that uses a propagation optical system having the lens configuration shown in FIG. The "angle of view" of the propagation optical system is as follows for the vertical direction (Y direction), horizontal direction (X direction), and diagonal direction. Angle of view: Vertical: 17.2 degrees Horizontal: 36.0 degrees Diagonal: 40.0 degrees Also, the virtual image distance is 1m. The data for Example 4 is shown in Table 13.

[0072] [Table 13]

[0073] In FIG. 5 showing Example 4, reference numeral 10 indicates the image display surface of the image display element, and in Table 13, surface number: 0 indicates the image display surface, surface numbers: 1 to 11 indicate the relay optical system RL, surface numbers: 1 to 6 on the image display element side of the aperture with surface number: 7 indicate the front relay group RL1, and surface numbers: 8 to 11 indicate the rear relay group RL2. Surface numbers 12 and 13 indicate an intermediate optical element LI. The intermediate optical element LI is a cylindrical lens, and the surface facing the image display element is an aspheric cylindrical lens surface, and Rx of surface number 12 is the “paraxial curvature” of the non-circular arc shape in a specific cross section. Surface numbers 14 to 17 indicate the collimator optical system LC, surface numbers 18 and 19 indicate parallel plate-like light guiding members, and the surface distance between surface numbers 18 and 19 is a value calculated according to the number of reflections within the light guiding member. The distance from surface 21 to the observer's eye is the "eye relief" and is 15 mm.

[0074] "Aspheric data" The aspheric data of the aspheric surfaces is shown in Table 14 following Table 2.

[0075] [Table 14]

[0076] Table 15 shows the aspheric surface data in the XZ plane of surface number 12, which is the “specific cross section.”

[0077] [Table 15]

[0078] "Parameter value of the conditional expression" Table 16 shows the values ​​of conditional expressions (1) to (7) for the propagation optical system of Example 4.

[0079] [Table 16]

[0080] The parameter "H" in conditional formula (1) is "H=6.0 mm."

[0081] "Example 5" The fifth embodiment uses a propagation optical system having the lens configuration shown in FIG. The "angle of view" of the propagation optical system is as follows for the vertical direction (Y direction), horizontal direction (X direction), and diagonal direction. Angle of view: Vertical (Y) 19.6 degrees, Horizontal (X) 34.7 degrees, Diagonal 40.0 degrees The virtual image distance is "virtually infinite."

[0082] The data for Example 5 are shown in Table 17 following Table 1.

[0083] [Table 17]

[0084] "Aspheric data" The aspheric data of the aspheric surfaces is shown in Table 18 following Table 2.

[0085] [Table 18]

[0086] Table 19 shows the aspheric surface data in the XZ plane of surface number 14, which is the “specific cross section”.

[0087] [Table 19]

[0088] Table 20 shows the values ​​of conditional expressions (1) to (7) for the propagation optical system of Example 5.

[0089] [Table 20]

[0090] The parameter "H" in conditional formula (1) is "H=6.0 mm."

[0091] 8 to 12 show "transverse aberration diagrams" relating to the propagation optical systems used in Examples 1 to 5. FIG.

[0092] These lateral aberration diagrams show the lateral aberration at combinations of positions "1, 2, 3" in the vertical direction (up and down direction) and positions (a), (b), and (c) in the horizontal direction (sideways direction) in the virtual image shown in Figure 7. Taking the lateral aberration diagram shown in Fig. 8 as an example, the left diagram in Fig. 8 is at position (a) on the virtual image shown in Fig. 7, and the lateral aberrations at positions "1, 2, 3" in Fig. 7 are shown successively from bottom to top in the left diagram in Fig. 8. The left side in this left diagram relates to the "XZ cross section," and the right side relates to the "YZ cross section." That is, the left diagram in FIG. 8 is at positions (1,(a)), (2,(a)), and (3,(a)) on the virtual image in FIG. Similarly, the central image in FIG. 8 corresponds to positions (1,(b)), (2,(b)), and (3,(b)) on the virtual image in FIG. 7, and the right image in FIG. 8 corresponds to positions (1,(c)), (2,(c)), and (3,(c)) on the virtual image in FIG. 7. 9 to 12 are the same as in FIG. As is clear from the lateral aberrations shown in FIGS. 8 to 12, the propagation optical systems used in Examples 1 to 5 have excellent performance. Furthermore, all of the propagation optical systems of Examples 1 to 5 have wide angles of view in the horizontal, vertical, and diagonal directions, and in particular, an extremely wide angle of view of 35 degrees or more is achieved in the horizontal direction (the longitudinal direction of the image display area), ensuring very good imaging performance.

[0093] Above, Examples 1 to 5 have been described as specific examples of the propagation optical system 20 in Fig. 1. In Examples 1 to 5, the rotationally asymmetric surface of the intermediate optical element L1 was a cylindrical lens surface, had an aspheric shape in a specific cross section, and had zero power in the second specific cross section. The "non-rotationally symmetric surface" of the intermediate optical element included in the propagation optical system of the present invention is not limited to the cylindrical lens surface as described above. In addition to the toroidal surface and the like given above as examples of the rotationally asymmetric surface, various other surfaces are possible. Hereinafter, a case will be described in which an "anamorphic aspheric surface" is used as the rotationally asymmetric surface. In this specification, the term "anamorphic aspheric surface" is as follows. Considering the "sections including the optical axis" of an anamorphic aspheric surface, the section with the strongest positive power among these sections is called "specific section 1." Among the sections including the optical axis, the section perpendicular to this specific section 1 is called "specific section 2." The term "anamorphic aspheric surface" as used in this specification refers to a rotationally asymmetric surface in which the cross-sectional shapes at specific cross section 1 and specific cross section 2 are both aspheric. The "specific cross section" described above is the same as the above specific cross section 1, but the "second specific cross section" in the above description corresponds to the "direction of no curvature of the cylindrical lens" and has a straight cross-sectional shape. The second specific cross section of the anamorphic aspheric surface differs from the second specific cross section in that the cross-sectional shape of the second specific cross section is aspheric.

[0094] In the specific examples 6 to 9 given below, the surface shape of the non-rotational body main surface is specified by the following formula (B). Z={CxX 2 +CyY 2} / [1+√(1-(1+Kx)Cx 2 X 2 -(1+Ky)Cy 2 Y 2 )] +AR 4 ·((1-AP 4 )X 2 +(1+AP 4 )Y2 ) 2 +AR 6 ·((1-AP 6 )X 2 +(1+AP 6 )Y 2 ) 3 +AR 8 ·((1-AP 8 )X 2 +(1+AP 8 )Y 2 ) 4 +AR 10 ·((1-AP 10 )X 2 +(1+AP 10 )Y 2 ) 5 (B) In formula (B), Cx is the paraxial curvature in the X-axis direction (the reciprocal of the paraxial radius of curvature), Cy is the paraxial curvature in the Y-axis direction, X and Y are the position coordinates of the anamorphic aspheric surface from the optical axis, and Z is the anamorphic aspheric surface amount at these position coordinates.

[0095] The meanings of the other symbols are as follows:

[0096] Kx: X-axis conic constant Ky: Y-axis conic constant AR 4 : Rotationally symmetric fourth-order coefficient AR 6 : Rotationally symmetric sixth order coefficient AR 8 : Rotationally symmetric 8th order coefficient AR 10 : Rotationally symmetric 10th order coefficient AP 4 : Rotationally asymmetric fourth-order coefficient AP 6 : Rotationally asymmetric sixth order coefficient AP 8 : Rotationally asymmetric eighth-order coefficient AP 10 : Rotationally asymmetric 10th order coefficient The X-axis direction corresponds to the horizontal direction described above, and the Y-axis direction corresponds to the vertical direction.

[0097] The relay optical system LR and the collimator optical system LC are rotationally symmetric with respect to the optical axis and have positive power.

[0098] As mentioned above, in order to reduce the lens diameter of the collimator lens LC while maintaining high performance and a certain degree of optical total length, it is better for the propagation optical system to "form an intermediate image", and the diameter of the relay optical system RL can be made relatively small. By having the relay optical system RL, it is also possible to deal with cases where it is necessary to secure "the distance between the image display element and the propagation optical system" for mechanical or electrical reasons. Referring to Figure 1, the propagation optical system 20 is composed of, in order from the image display element 10 side, a relay optical system RL, an intermediate optical element LI, and a collimator optical system LC. Since the intermediate image IN is formed between the relay optical system RL and the collimator optical system LC, the position of the "anamorphic aspheric surface" of the intermediate optical element LI is close to the intermediate image IN, and spherical aberration and coma aberration caused by non-rotational symmetry can be reduced.

[0099] It is preferable that the "specific cross section 1" of the anamorphic aspheric surface corresponds to the horizontal direction of the displayed virtual image (x direction in FIG. 1). In this way, in the specific cross section 1, the main rays off the axis of the propagation optical system 20 can be made to intersect with the optical axis near the entrance part 30A of the light-guiding member 30, and the light can be efficiently propagated to the eye EY. In particular, even if the opening width in the direction corresponding to the specific cross section 1 of the incident part 30A of the light-guiding member 30 (opening width in the xy plane) is small, the loss of the chief ray due to the incident part 30A can be reduced and the light utilization efficiency can be improved. In other words, even if the light-guiding member 30 is made thin (reduced in size and weight), the loss of the chief ray can be reduced.

[0100] It is preferable that the "specific cross section 2" corresponds to the vertical direction of the displayed virtual image (the y direction in FIG. 1). In this way, in the specific cross section 2, the principal rays off the axes of the propagation optical system 20 can be made to enter the specific cross section 2 so as to intersect with the optical axis near the eye EY, and the light can be efficiently propagated to the eye EY.

[0101] In the above configuration, the shape of the anamorphic aspheric surface is such that the paraxial radius of curvature Rp of the "specific cross section 1" having the strongest positive power among the cross sections, and the paraxial radius of curvature Rn of the specific cross section 2 perpendicular to the specific cross section 1, are set to satisfy the following conditions: (11) -0.9 <(Rp+Rn) / (Rp-Rn) < -0.3 It is preferable that the shape satisfies the above. If the upper limit value of condition (11) is exceeded, the difference in power between the specific cross section 1, which has the strongest positive power, and the specific cross section 2 perpendicular to it, becomes excessively large, and the off-axis chief rays of the propagation optical system 20 at the specific cross section 1 intersect with the optical axis on the propagation optical system side rather than near the entrance portion 30A of the light-guiding member 30, which makes it difficult to efficiently propagate light to the eye EY. If the lower limit value is exceeded, the difference in power between the specific cross section 1, which has the strongest positive power, and the specific cross section 2 perpendicular to it, becomes too small, and in the specific cross section 1, the off-axis chief rays of the propagation optical system 20 intersect with the optical axis on the eye EY side rather than near the entrance portion 30A of the light-guiding member 30, making it difficult to efficiently propagate light to the eye EY.

[0102] The paraxial radius of curvature can be determined by measuring the surface and fitting it using the least squares method. In order to achieve higher performance, it is preferable that the paraxial radius of curvature Rn of the specific cross section 2 is negative.

[0103] It is preferable that the "non-arc shape" of the specific cross section 1 is a "shape in which the positive power decreases the farther away from the optical axis." In this way, the off-axis chief rays of the propagation optical system can intersect with the optical axis at a position closer to the entrance part 30A, and the light can be more efficiently "propagated to the eye EY."

[0104] The above-mentioned "shape in which the positive power becomes weaker as it moves away from the optical axis" is a shape in which the maximum sag amount: Sagp of the shape of a specific cross section 1 having the strongest positive power among the cross sections of the anamorphic aspheric surface, and the sag amount: Sag_rp of a cross section formed by a circle of the paraxial curvature of the cross section at the same ray height, are satisfied under the following conditions: (12) 0.6 < Sagp / Sag_rp < 1.0 It is preferable that the shape satisfies the above. If the upper limit of condition (12) is exceeded, the high off-axis chief ray of the propagation optical system 20 will intersect with the optical axis closer to the propagation optical system than the vicinity of the entrance part 30A of the light-guiding member 30, making it difficult to efficiently propagate light to the eye EY. Conversely, if the lower limit of condition (12) is exceeded, the high off-axis chief ray of the propagation optical system 20 will intersect with the optical axis closer to the eye EY than the vicinity of the entrance part 30A of the light-guiding member 30, making it difficult to efficiently propagate light to the eye EY.

[0105] It is preferable that the "non-arc shape" of the specific cross section 2 is a "shape in which the power decreases the farther away from the optical axis." In this way, the off-axis chief ray of the propagation optical system can intersect with the optical axis at a position closer to the entrance part 30A, and the light can be more efficiently "propagated to the eye EY."

[0106] The "shape in which the power decreases as it moves away from the optical axis" of the specific cross section 2 is determined by the following condition: the maximum value of the sag amount of the shape of the specific cross section 2 perpendicular to the specific cross section 1, which has the strongest positive power among the cross sections of the anamorphic aspheric surface, Sagn, and the sag amount of the cross section made by the circle of the paraxial curvature of the cross section, Sag_rn, at the same ray height. (13) 0.6 < Sagn / Sag_rn < 1.0 It is preferable that the shape satisfies the above.

[0107] If the upper limit of condition (13) is exceeded, the off-axis chief ray of the propagation optical system 20 will intersect with the optical axis behind the eye EY, making it difficult to efficiently propagate light to the eye EY.

[0108] Conversely, if the lower limit of condition (13) is exceeded, the off-axis chief ray of the propagation optical system 20 will intersect with the optical axis in front of the eye EY, making it difficult to efficiently propagate light to the eye EY.

[0109] Of course, even when an anamorphic aspheric surface is used, it is preferable to satisfy any one or more of the conditions (2) to (7) described above, and by satisfying any one or more of these conditions, it is possible to further improve the performance of the propagation optical system.

[0110] Regarding the above condition in relation to the anamorphic aspheric surface, in condition (6), "Pos1" is the position on the optical axis of the anamorphic aspheric surface. distance from the position of the intermediate image and the intermediate image is negative when it is on the image display element side of the anamorphic aspheric surface. “Y” is the diagonal length of the image display region of the image display element. If the upper or lower limit of condition (6) is exceeded, the distance between the anamorphic aspheric surface and the intermediate image becomes large, making it difficult to suppress the occurrence of non-rotationally symmetric spherical aberration and coma aberration.

[0111] Also, even when an anamorphic aspheric surface is used, the relay optical system can be configured by arranging, in order from the image display element side to the intermediate optical element side, the aforementioned "pre-relay group" and "post-relay group," both of which have positive refractive power, so that the distance between the pre-relay group and the post-relay group is "the widest in all relay optical systems." By doing so, it is possible to ensure an appropriate distance between the pre-relay group and the post-relay group, and to ensure the overall length of the propagation optical system, while at the same time making good correction for various aberrations. In this case as well, by making the thickness of the relay optical system: TLR and the distance between the pre-relay group and the post-relay group: TLRa satisfy condition (2), the space for the pre-relay group and the post-relay group can be made an appropriate size, and good correction of various aberrations can be achieved within the relay optical system while ensuring the overall length of the propagation optical system. When the relay optical system is constructed as described above using the pre-relay group and the pre-relay group, it is preferable that the pre-relay group be constructed by arranging, in order from the image display element side to the intermediate optical element side, a positive lens, a negative lens, and a positive lens. By configuring the front relay group in this manner, it is possible to sufficiently correct chromatic aberration while in particular spherical aberration, coma, etc. It is preferable that the lens surfaces of the positive lens, negative lens, and positive lens are aspheric.

[0112] The rear relay group can be constructed by arranging, in order from the image display element side to the intermediate optical element side, a positive lens and a negative lens. With this configuration, residual aberrations in the pre-relay group and collimator optical system are corrected by two lenses, one positive and one negative, making it easy to sufficiently correct various aberrations. When the post-relay group is composed of a positive lens and a negative lens, it is preferable that the lens surfaces of the two lenses are aspheric.

[0113] In addition, in condition (3), if TLA is the distance from the anamorphic aspheric surface of the intermediate optical element to the surface of the collimator optical system closest to the light-guiding member, and TL is the distance from the surface of the relay optical system closest to the image display element to the surface of the collimator optical system closest to the light-guiding member, then the propagation optical system can be made compact by having TLA and TL satisfy condition (3).

[0114] By satisfying the condition (4), even in the case of using an anamorphic aspheric surface, it is possible to properly maintain the thickness of the collimator optical system while preventing the diameters of the intermediate optical element having the anamorphic aspheric surface and the collimator optical system from becoming excessively large, thereby enabling favorable correction of various aberrations in the collimator optical system.

[0115] Moreover, by satisfying the condition (5), the lateral magnification of the relay optical system: β_relay can be set within a suitable range.

[0116] Similarly to the above, by satisfying conditions (6) and (7), it is possible to achieve even higher performance in the propagation optical system.

[0117] Examples 6 to 9 below are specific examples of a propagation optical system that uses an "anamorphic aspheric surface" as a rotationally asymmetric surface. FIGS. 13 to 16 sequentially show the lens configurations of the propagation optical systems of Examples 6 to 9 following FIGS. 2 to 6. FIG. The X and Y directions are defined in the same manner as in FIGS. In Examples 6 to 9, the size of the image display element is 3.12 mm in the Y direction (vertical direction), 4.992 mm in the X direction (horizontal direction), and diagonal length: 5.89 mm, which is the same as in Examples 1, 2, 3, and 5 given above.

[0118] That is, in the virtual image display device shown in Fig. 1, the virtual image observed by the observer through the light guiding member 30 is a "horizontally elongated image" and is observed as a plane parallel to the xy plane in Fig. 1(a). In correspondence with this virtual image, the longitudinal direction of the image display area is the horizontal direction ("X direction"), and the lateral direction is the vertical direction ("Y direction"). The direction perpendicular to the X and Y directions is taken as the Z direction, which coincides with the optical axis direction of the propagation optical system in FIGS. 13 to 16, (a) shows the "cross-sectional shape in the YZ plane" of the propagation optical system, and (b) shows the "cross-sectional shape in the XZ plane" of the propagation optical system. The left side of the figure is the object side. Therefore, the up-down direction in (a) of these figures is the Y direction, and the up-down direction in (b) is the X direction.

[0119] 13 to 16 are the same as those in FIGS. 2 to 6. That is, by using the symbols in FIG. 1, the "cover glass" provided on the image display surface that matches the image display area of ​​the image display element is represented by symbol 11, the relay optical system is represented by symbol RL, and the collimator optical system is represented by symbol LC. The intermediate optical element is designated by the reference character LII, the reference character RL1 denotes the "pre-relay group," and the reference character RL2 denotes the "post-relay group." Also, the reference character S denotes the "aperture stop." Reference numeral 30 in FIGS. 13 to 16 denotes a "light guide member."

[0120] In the examples of Figures 13 to 16, the propagation optical system is composed of a relay optical system RL, an intermediate optical element LII, and a collimator optical system LC, arranged in that order from the image display element side (the left side of the figure) to the light-guiding member 30 side, and the relay optical system RL is composed of a pre-relay group RL1 and a post-relay group RL2. In each example, the pre-relay group RL1 is composed of three lenses, positive, negative, and positive, in that order from the image display element side, and the post-relay group RL2 is composed of two lenses, positive and negative, in the same order. The collimator optical system LC is composed of two lenses, negative and positive, in the same order.

[0121] The lenses that make up the pre-relay group RL1, the post-relay group RL2, and the collimator optical system LC are rotationally symmetrical about the optical axis (Z direction), and the pre-relay group RL1, the post-relay group RL2, and the collimator optical system LC, which are arranged in the optical axis direction (Z direction), are also rotationally symmetrical about the optical axis. The relay optical system RL and the pre-relay lens unit RL1 and the post-relay lens unit RL2 that constitute the relay optical system RL all have positive power, and the collimator optical system LC also has positive power. The intermediate optical element LII in the propagation optical system in Figures 13 to 16 is a lens having an "anamorphic aspheric surface", with the surface on the image display element side (the relay optical system RL side) being anamorphic aspheric and the surface on the collimator optical system LC side being flat. An anamorphic aspheric surface is a "non-rotationally symmetric curved surface," and "specific cross section 1," which is the cross section including the optical axis of the non-rotationally symmetric curved surface and has the strongest positive power, is the XZ plane (the horizontal plane including the optical axis) as shown in Figures 13 to 16(a), and specific cross section 2 shown in Figures 13 to 16(b) is the YZ plane, and both are non-arc shapes.

[0122] Specific examples 6 to 9 of the virtual image display device using the propagation optical system shown in FIGS. 13 to 16 will be given below. The symbols in Examples 6 to 9 have the same meanings as in Examples 1 to 5 described above, and the aspheric surface is expressed by the above-mentioned formula (A), and the anamorphic aspheric surface is expressed by the above-mentioned formula (B). The unit of measurement for quantities having a dimension of length is "mm" unless otherwise specified. In Examples 6 to 9, the light-guiding member used is a parallel plate-like member as described in Examples 1 to 5, and the portion corresponding to the observation light extraction section 30B in the example shown in Figure 1 is composed of multiple semi-transparent surfaces inclined in the Y direction.

[0123] Also in Table 21 showing data for Examples 6 to 9, in the surface numbers shown in the leftmost column of the table, surface number: 0 indicates the image display surface, surface numbers: 1 and 2 indicate both sides of the cover glass, surface numbers: 3 to 13 indicate the relay optical system RL, surface numbers: 3 to 8 on the image display element side of the aperture with surface number: 9 indicate the front relay group RL1, and surface numbers: 10 to 13 indicate the rear relay group RL2.

[0124] Surface numbers 14 and 15 indicate an intermediate optical element LII. The intermediate optical element LII is a lens having an anamorphic aspheric surface, and its image display element side is the anamorphic aspheric surface. Rx of surface number 14 is the “paraxial curvature” of the non-circular arc shape in specific cross section 1, and Ry is the “paraxial curvature” of the non-circular arc shape in specific cross section 2. Surface numbers 16 to 19 indicate the collimator optical system LC, surface numbers 20 and 21 indicate parallel plate-like light guiding members, and the surface distance between surface numbers 20 and 21 is a value converted according to the number of reflections within the light guiding member.

[0125] "Example 6" The sixth embodiment is an embodiment that uses a propagation optical system having the lens configuration shown in FIG. The "angle of view" of the propagation optical system is as follows for the vertical direction (Y direction), horizontal direction (X direction), and diagonal direction.

[0126] Angle of view: Vertical (Y) 18.5 degrees, Horizontal (X) 35.4 degrees, Diagonal 40.0 degrees Virtual image distance: 1m. The data for Example 6 is shown in Table 21.

[0127] [Table 21]

[0128] "Aspheric data" The aspheric data of the aspheric surfaces is shown in Table 22 following Table 2.

[0129] [Table 22]

[0130] "Anamorphic aspheric coefficients" The conic constants of the anamorphic aspheric surfaces are given in Table 23.

[0131] [Table 23]

[0132] The rotationally symmetric coefficients of the anamorphic aspheric surface are given in Table 24.

[0133] [Table 24]

[0134] The rotationally asymmetric coefficients of the anamorphic aspheric surface are shown in Table 25.

[0135] [Table 25]

[0136] "Parameter value of the conditional expression" Table 26 shows the parameter values ​​of each conditional expression of the propagation optical system of Example 6.

[0137] [Table 26]

[0138] The ray height for calculating the parameter of conditional expression (12) is H=5.9, and the ray height for calculating the parameter of conditional expression (13) is H=3.7.

[0139] "Example 7" The seventh embodiment is an embodiment that uses a propagation optical system having the lens configuration shown in FIG. The "angle of view" of the propagation optical system is as follows for the vertical direction (Y direction), horizontal direction (X direction), and diagonal direction.

[0140] Angle of view: Vertical (Y) 18.8 degrees, Horizontal (X) 35.5 degrees, Diagonal 40.0 degrees Virtual image distance: 1m. The data for Example 7 are shown in Table 27.

[0141] [Table 27]

[0142] "Aspheric data" The aspheric data of the aspheric surfaces is shown in Table 28 following Table 2.

[0143] [Table 28]

[0144] "Anamorphic aspheric coefficients" The conic constants of the anamorphic aspheric surfaces are given in Table 29.

[0145] [Table 29]

[0146] The rotationally symmetric coefficients of the anamorphic aspheric surface are given in Table 30.

[0147] [Table 30]

[0148] The rotationally asymmetric coefficients of the anamorphic aspheric surface are shown in Table 31.

[0149] [Table 31]

[0150] "Parameter value of the conditional expression" Table 32 shows the parameter values ​​of the conditional expressions of the propagation optical system of Example 7.

[0151] [Table 32]

[0152] The ray height for calculating the parameter of conditional expression (12) is H=5.9, and the ray height for calculating the parameter of conditional expression (13) is H=3.7.

[0153] "Example 8" The eighth embodiment is an embodiment that uses a propagation optical system having the lens configuration shown in FIG. The "angle of view" of the propagation optical system is as follows for the vertical direction (Y direction), horizontal direction (X direction), and diagonal direction.

[0154] Angle of view: Vertical (Y) 18.9 degrees, Horizontal (X) 35.3 degrees, Diagonal 40.0 degrees Virtual image distance: 1m. The data for Example 8 are shown in Table 33.

[0155] [Table 33]

[0156] "Aspheric data" The aspheric data of the aspheric surfaces is shown in Table 34 following Table 2.

[0157] [Table 34]

[0158] "Anamorphic aspheric coefficients" The conic constants of the anamorphic aspheric surfaces are given in Table 35.

[0159] [Table 35]

[0160] The rotationally symmetric coefficients of the anamorphic aspheric surface are given in Table 36.

[0161] [Table 36]

[0162] The rotationally asymmetric coefficients of the anamorphic aspheric surface are shown in Table 37.

[0163] [Table 37]

[0164] "Parameter value of the conditional expression" Table 38 shows the parameter values ​​of each conditional expression of the propagation optical system of Example 8.

[0165] [Table 38]

[0166] The ray height for calculating the parameter of conditional expression (12): H=5.9, and the ray height for calculating the parameter of conditional expression (13): H=3.7.

[0167] "Example 9" The ninth embodiment is an embodiment that uses a propagation optical system having the lens configuration shown in FIG. The "angle of view" of the propagation optical system is as follows for the vertical direction (Y direction), horizontal direction (X direction), and diagonal direction.

[0168] Angle of view: Vertical (Y) 19.5 degrees, Horizontal (X) 34.6 degrees, Diagonal 40.0 degrees Virtual image distance: 1m. The data for Example 9 are shown in Table 39.

[0169] [Table 39]

[0170] "Aspheric data" The aspheric data of the aspheric surfaces is shown in Table 40 following Table 2.

[0171] [Table 40]

[0172] "Anamorphic aspheric coefficients" The conic constants of the anamorphic aspheric surfaces are given in Table 41.

[0173] [Table 41]

[0174] The rotationally symmetric coefficients of the anamorphic aspheric surface are given in Table 42.

[0175] [Table 42]

[0176] The rotationally asymmetric coefficients of the anamorphic aspheric surface are shown in Table 43.

[0177] [Table 43]

[0178] "Parameter value of the conditional expression" Table 44 shows the parameter values ​​of each conditional expression of the propagation optical system of Example 9.

[0179] [Table 44]

[0180] The ray height for calculating the parameter of conditional expression (12) is H=5.9, and the ray height for calculating the parameter of conditional expression (13) is H=3.7.

[0181] Figures 17 to 20 show "transverse aberration diagrams" relating to the propagation optical systems used in Examples 6 to 9, following the example of Figures 8 to 12. As in Figures 8 to 12, these diagrams show the transverse aberration at positions combining positions "1, 2, 3" in the vertical direction (up-down direction) and positions (a), (b), and (c) in the horizontal direction (side-by-side direction) in the virtual image shown in Figure 7. As is clear from the lateral aberrations shown in FIGS. 17 to 20, the propagation optical systems used in Examples 6 to 9 have excellent performance. Like Examples 1 to 5, the propagation optical systems of Examples 6 to 9 all have wide angles of view in the horizontal, vertical, and diagonal directions, and in particular, an extremely wide angle of view of 35 degrees or more is achieved in the horizontal direction (the longitudinal direction of the image display area), ensuring very good imaging performance.

[0182] It should be noted that all of the illustrated aberration diagrams are calculated based on the assumption that an image is formed using an ideal lens with a focal length of 17 mm.

[0183] By using the propagation optical system shown in Examples 1 to 9, a high-performance virtual image display device can be configured as an HMD in the form of "glasses-type display such as smart glasses." In particular, even when a thin light-guiding member is used, good image performance can be ensured due to high light utilization efficiency and a wide angle of view, so that the virtual image display device can be made lightweight and compact.

[0184] Although a preferred embodiment of the invention has been described above, the invention is not limited to the specific embodiment described above, and various modifications and variations are possible within the spirit of the invention described in the claims, unless otherwise specifically limited in the above description. The effects described in the embodiments of the present invention are merely a list of preferred effects resulting from the invention, and the effects of the invention are not limited to "those described in the embodiments." [Explanation of symbols]

[0185] 10 Image display element 20 Propagation Optics 30 Light guide member EY Eyes RL Relay Optical System RL1 Relay front group RL2 Relay rear group LI Intermediate Optical Element LII. Intermediate optical element with anamorphic aspheric surface IN intermediate image LC Collimator Optical System [Prior art documents] [Patent documents]

[0186] [Patent Document 1] Patent No. 5698297 [Patent Document 2] Patent No. 5421285

Claims

1. A propagation optical system used in a virtual image display device that displays a virtual image of an image by guiding light from an image display element on which an image is displayed to a light guiding member and emitting the light to an outside from the light guiding member, the propagation optical system propagating light from the image display element to the light guiding member, a first optical system, an intermediate optical element, and a second optical system are arranged in this order from the image display element side toward the light guiding member side, and an intermediate image of an image displayed on the image display element is formed between the first optical system and the second optical system, the intermediate optical element has a non-rotationally symmetric curved surface having a shape that is non-rotationally symmetric with respect to an optical axis, and a cross-sectional shape of a specific cross-section that is a cross-section having the strongest positive power among cross-sections of the non-rotationally symmetric curved surface including the optical axis is a non-arcuate cross-section; A propagation optical system, wherein the non-rotationally symmetric curved surface of the intermediate optical element is an anamorphic aspheric surface.

2. A propagation optical system for use in a virtual image display device that displays a virtual image of an image by guiding light from an image display element on which an image is displayed to a light guiding member and emitting the light from the light guiding member to the outside, the propagation optical system propagating light from the image display element to the light guiding member, a first optical system, an intermediate optical element, and a second optical system are arranged in this order from the image display element side toward the light guiding member side, and an intermediate image of an image displayed on the image display element is formed between the first optical system and the second optical system, the intermediate optical element has a non-rotationally symmetric curved surface having a shape that is non-rotationally symmetric with respect to an optical axis, and a cross-sectional shape of a specific cross-section that is a cross-section having the strongest positive power among cross-sections of the non-rotationally symmetric curved surface including the optical axis is a non-arcuate cross-section; the second optical system is a propagation optical system including a negative lens and a positive lens arranged in this order from the intermediate optical element side toward the light guiding member side.

3. A propagation optical system for use in a virtual image display device that displays a virtual image of an image by guiding light from an image display element on which an image is displayed to a light guiding member and emitting the light from the light guiding member to the outside, the propagation optical system propagating light from the image display element to the light guiding member, a first optical system, an intermediate optical element, and a second optical system are arranged in this order from the image display element side toward the light guiding member side, and an intermediate image of an image displayed on the image display element is formed between the first optical system and the second optical system, the intermediate optical element has a non-rotationally symmetric curved surface having a shape that is non-rotationally symmetric with respect to an optical axis, and a cross-sectional shape of a specific cross-section that is a cross-section having the strongest positive power among cross-sections of the non-rotationally symmetric curved surface including the optical axis is a non-arcuate cross-section; The first optical system is a propagation optical system comprising, in order from the image display element side to the intermediate optical element side, a first front group and a first rear group, both of which have positive power, and the distance between the first front group and the first rear group is the widest in the first optical system.

4. A propagation optical system for use in a virtual image display device that displays a virtual image of an image by guiding light from an image display element on which an image is displayed to a light guiding member and emitting the light from the light guiding member to the outside, the propagation optical system propagating light from the image display element to the light guiding member, a first optical system, an intermediate optical element, and a second optical system are arranged in this order from the image display element side toward the light guiding member side, and an intermediate image of an image displayed on the image display element is formed between the first optical system and the second optical system, the intermediate optical element has a non-rotationally symmetric curved surface having a shape that is non-rotationally symmetric with respect to an optical axis, and a cross-sectional shape of a specific cross-section that is a cross-section having the strongest positive power among cross-sections of the non-rotationally symmetric curved surface including the optical axis is a non-arcuate cross-section; The propagation optical system, wherein the intermediate optical element is a cylindrical lens.

5. 5. The propagation optical system according to claim 1 , A propagation optical system, wherein the non-circular shape of the specific cross section has a shape in which the positive power decreases as the distance from the optical axis increases.

6. 6. The propagation optical system according to claim 5, The maximum value of the difference in sag between the non-arcuate shape of the specific cross section and the arc of the paraxial circle of curvature of the non-arcuate shape: Sag, and the effective ray height from the optical axis: H are satisfied under the condition: (1) 0.02 < Sag / H < 0.25 A propagation optical system that satisfies the above.

7. 2. The propagation optical system according to claim 1, Among the cross sections of the anamorphic aspheric surface, the paraxial radius of curvature of the cross section having the strongest positive power: Rp, and the paraxial radius of curvature of the cross section perpendicular to the cross section having the strongest positive power: Rn are (11) -0.9 <(Rp+Rn) / (Rp-Rn)<-0.3 A propagation optical system that satisfies the above.

8. 8. A propagation optical system according to claim 1, A propagation optical system, characterized in that the shape of a cross section having the strongest positive power among the cross sections of the anamorphic aspheric surface is a shape in which the positive power becomes weaker as it moves away from the optical axis.

9. 9. The propagation optical system according to claim 8, The maximum value of the sag amount of the shape of the cross section having the strongest positive power among the cross sections of the anamorphic aspheric surface: Sagp, and the sag amount of the cross section formed by the circle of the paraxial curvature of the cross section at the same ray height: Sag_rp are satisfied under the following conditions: (12) 0.6 < Sagp / Sag_rp < 1.0 A propagation optical system that satisfies the above.

10. A propagation optical system according to any one of claims 1 and 7 to 9, The maximum value of the sag amount of the shape of a cross section perpendicular to the cross section having the strongest positive power among the cross sections of the anamorphic aspheric surface: Sagn, and the sag amount of a cross section formed by a circle of the paraxial curvature of the cross section at the same ray height: Sag_rn are satisfied under the following conditions: (13) 0.6 < Sagn / Sag_rn < 1.0 A propagation optical system that satisfies the above.

11. 4. The propagation optical system according to claim 3, The thickness of the first optical system: TLR, and the distance between the first front group and the first rear group: TLRa are satisfied under the following conditions: (2) 0.4< TLRa / TLR <0.7 A propagation optical system that satisfies the above.

12. The propagation optical system according to claim 3 or 11, the first front group is configured by three lenses, arranged in this order from the image display element side to the intermediate optical element side: a positive lens, a negative lens, and a positive lens;

13. A propagation optical system according to any one of claims 3, 11 and 12, the first rear group is configured by arranging, in order from the image display element side toward the intermediate optical element side, a positive lens and a negative lens, in this order, a propagation optical system.

14. A propagation optical system according to any one of claims 1 to 13, A distance TLA from the non-rotationally symmetric curved surface of the intermediate optical element to a surface of the second optical system closest to the light guide member, and a distance TL from a surface of the first optical system closest to the image display element to a surface of the second optical system closest to the light guide member are satisfied under the following conditions: (3) 0.1< TLA / TL <0.5 A propagation optical system that satisfies the above.

15. A propagation optical system according to any one of claims 1 to 14, The thickness of the second optical system: TLC, and the thickness of the first optical system: TLR are determined under the following conditions: (4) 0.3< TLC / TLR <0.6 A propagation optical system that satisfies the above.

16. A propagation optical system according to any one of claims 1 to 15, The lateral magnification of the first optical system: β_relay is determined as follows: (5) -3.0<β_relay<-1.0 A propagation optical system that satisfies the above.

17. 17. A propagation optical system according to claim 1, The distance between the position on the optical axis of the non-rotationally symmetric curved surface and the position of the intermediate image: Pos1, and the diagonal length of the image display area of ​​the image display element: Y are satisfied under the following conditions: (6) -0.5< Pos1 / Y <0.5 A propagation optical system that satisfies the above.

18. A propagation optical system according to any one of claims 1 to 17, the first optical system is configured to include, in order from the image display element side to the intermediate optical element side, a first front group and a first rear group, both of which have positive power; The focal length of the first optical system: f_r (>0), and the focal length of the first front group: f_rf are set to satisfy the following condition: (7) 0.4< f_r / f_rf <0.8 A propagation optical system that satisfies the above.

19. A virtual image display device which transmits light from an image display element displaying an image to a light guiding member by a propagation optical system, guides the light through the light guiding member, and emits the light to the outside from the light guiding member, thereby displaying a virtual image of the image by the emitted light, A virtual image display device using the propagation optical system according to claim 1 .

20. A head-mounted display having a virtual image display device according to claim 19.

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