JP7619176B2 - Propagation optical system, virtual image display device, and head-mounted display - Google Patents

Description

The present invention relates to a propagation optical system, a virtual image display device, and a head-mounted display.

There is a known virtual image display device that enlarges a two-dimensional image and displays the enlarged virtual image so that the viewer can view it. For example, Patent Document 1 describes a light-guiding type virtual image display device as an example of this type of virtual image display device.

As described in Patent Document 1, a light-guiding type virtual image display device is configured to propagate light from an image display element (hereinafter referred to as "image light") to a light-guiding member by a propagation optical system, guide the image light propagated from the propagation optical system by the light-guiding member, and emit the guided image light toward an observer so that the observer can observe the emitted image light as a magnified virtual image.

Patent No. 5421285

In order to ensure a wide angle of view in a light-guiding type virtual image display device, for example, it is possible to configure the propagation optical system with a large diameter. However, increasing the diameter of the propagation optical system is undesirable because it increases the size of the virtual image display device. In particular, in wearable devices such as head-mounted displays, the increase in size makes it difficult for the wearer to wear the device and increases the weight, increasing the burden on the wearer.

The present invention has been made in consideration of the above circumstances, and its purpose is to provide a propagation optical system that can be constructed in a compact size, and a virtual image display device and a head-mounted display that include such a propagation optical system.

The propagation optical system according to an embodiment of the present invention is an optical system that propagates light from an image display element that displays an image to a light guide member of a virtual image display device, and is configured to include a first optical system and a second optical system arranged in this order from the image display element side toward the light guide member side, and an intermediate image of the image is formed between the first optical system and the second optical system. An aperture is arranged in the first optical system. When the image formation position of the aperture, which is an object, by an optical element arranged on the light guide member side of the aperture among the optical elements included in the propagation optical system is defined as the aperture image formation position, the air conversion distance from the optical surface closest to the light guide member among the optical surfaces of each optical element included in the second optical system to the aperture image formation position is defined as TLS, and the distance from the optical surface closest to the image display element among the optical surfaces of each optical element included in the first optical system to the optical surface closest to the light guide member among the optical surfaces of each optical element included in the second optical system is defined as TL, the propagation optical system satisfies the following formula: 0.0<TLS/TL<0.3
Meet the following.

According to one embodiment of the present invention, there is provided a propagation optical system that can be configured to be compact, and a virtual image display device and a head-mounted display that include such a propagation optical system.

1 is a schematic diagram showing a state in which a head-mounted display, which is an example of a virtual image display device, is worn by a wearer, according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of an optical configuration of a propagation optical system according to an embodiment of the present invention. 1 is a perspective view showing a schematic configuration of a light guide member according to an embodiment of the present invention. 1 is a diagram showing an optical configuration of a propagation optical system according to a first numerical example of the present invention; 3A to 3C are diagrams showing spherical aberration, astigmatism, and distortion of the propagation optical system according to Numerical Example 1 of the present invention. 4A to 4C are diagrams showing lateral aberration of a propagation optical system according to Numerical Example 1 of the FIG. 11 is a diagram showing an optical configuration of a propagation optical system according to a second numerical example of the present invention. 6A to 6C are diagrams showing spherical aberration, astigmatism, and distortion of a propagation optical system according to a second numerical example of the present invention. 6A to 6C are diagrams showing lateral aberration of a propagation optical system according to a second numerical example of the present invention. FIG. 11 is a diagram showing an optical configuration of a propagation optical system according to a numerical example 3 of the present invention. 11A to 11C are diagrams showing spherical aberration, astigmatism, and distortion of a propagation optical system according to a third numerical example of the present invention. 11A to 11C are diagrams showing lateral aberration of a propagation optical system according to a third numerical example of the present invention. FIG. 11 is a diagram showing an optical configuration of a propagation optical system according to a numerical example 4 of the present invention. 11A to 11C are diagrams showing spherical aberration, astigmatism, and distortion of a propagation optical system according to Numerical Example 4 of the present invention. 11A to 11C are diagrams showing lateral aberration of a propagation optical system according to Numerical Example 4 of the present invention.

The following describes a propagation optical system, a virtual image display device, and a head-mounted display according to one embodiment of the present invention with reference to the drawings. In the following description, common or corresponding elements are denoted by the same or similar reference numerals, and duplicate descriptions are appropriately simplified or omitted.

Figure 1 is a schematic diagram showing a head-mounted display 1, which is an example of a virtual image display device, worn by a wearer. In Figure 1, the symbol EY indicates the wearer's left eye.

Note that while FIG. 1 shows a monocular head mounted display, binocular head mounted displays also fall within the scope of the present invention. A binocular head mounted display has, for example, a configuration similar to the monocular head mounted display 1 of FIG. 1 on the right eye side across the midline of the face. An example of a binocular head mounted display is smart glasses, which are glasses-type wearable devices. Note that monocular smart glasses that have a virtual image display device on only one eye side also fall within the scope of the present invention. Another example of a virtual image display device to which the present invention can be applied is a head-up display.

As shown in FIG. 1, the head mounted display 1 includes an image display element 10, a propagation optical system 20, and a light guide member 30. Light from the image display element 10 is propagated by the propagation optical system 20, and the propagated light is guided by the light guide member 30 and emitted to display a virtual image. In other words, the image display element 10, the propagation optical system 20, and the light guide member 30 constitute a light guide type virtual image display device.

Note that Figure 1 illustrates the main components necessary for explaining this embodiment, and some components, such as a housing that holds these main components (e.g., a glasses-type frame in the case of smart glasses), are omitted from the illustration as appropriate.

The head mounted display 1 is required to enable the wearer to view a virtual image with a wide angle of view. In order to ensure a wide angle of view, it is possible to configure the propagation optical system 20 with a large diameter. However, due to size constraints imposed by the fact that the glasses are worn by a person, there is a limit to configuring the propagation optical system 20 with a large diameter. For example, in the case of smart glasses, the propagation optical system 20 is built into the temples (also called "temples") of the frame. If the temples become thicker due to the large diameter of the propagation optical system 20, it becomes difficult for the wearer to wear the smart glasses, or the weight becomes heavier, increasing the burden on the wearer.

The propagation optical system 20 according to this embodiment is configured to prevent the propagation optical system 20 from becoming too large while ensuring a wide angle of view. In other words, the propagation optical system 20 can be configured to be small while ensuring a wide angle of view.

In the following description, the first horizontal direction in which the image display element 10 and the propagation optical system 20 are aligned is referred to as the z direction, the second horizontal direction perpendicular to the z direction is referred to as the y direction, and the vertical direction perpendicular to both the y direction and the z direction is referred to as the x direction. The mutually perpendicular X direction, Y direction, and Z direction form a right-handed system. Note that the names of the directions are used for convenience to explain the relative positional relationships of the components, and do not indicate absolute directions. Depending on the posture of the wearer wearing the head mounted display 1, for example, the z direction is not necessarily horizontal, but may be vertical.

The image display element 10 is an element that displays an image to be observed as a virtual image, and examples thereof include an OLED (Organic Light Emitting Diode) array, an LD (Laser Diode) array, an LED (Light Emitting Diode) array, a MEMS (Micro Electro Mechanical Systems), a DMD (Digital Micromirror Device), etc. When the image display element 10 is configured with an OLED array, for example, the size of the image display area (pixel array area) is 3 mm x 4 mm, and the number of pixels is about 10,000.

Light emitted from each pixel of the image display element 10 (i.e., image light) is incident on the propagation optical system 20.

Figure 2 is a diagram showing an example of the optical configuration of the propagation optical system 20. As shown in Figure 2, the propagation optical system 20 is composed of, in order from the image display element 10 side toward the light guide member 30 side, a relay optical system RL, which is a first optical system, and a collimator optical system LC, which is a second optical system. The relay optical system RL and the collimator optical system LC are rotationally symmetric with respect to the optical axis AX and have positive power.

In this embodiment, the expression "arranged" does not exclude configuration examples in which another optical element is added within the scope of the technical concept of the present invention. Examples of configuration examples that are not excluded include a configuration example in which a parallel plate that does not substantially contribute to the optical performance of the propagation optical system 20 is added, and a configuration example in which another optical element is added while maintaining the configuration and effect of the propagation optical system 20 according to this embodiment. In other words, a configuration in which an optical element of such a configuration is added to the propagation optical system 20 consisting of the first optical system (relay optical system RL) and the second optical system (collimator optical system LC) is also within the scope of the present invention.

The relay optical system RL forms an intermediate image IN of the image light incident from the image display element 10 between the relay optical system RL and the collimator optical system LC.

The intermediate image IN is the object for the virtual image observed by the wearer of the head mounted display 1. That is, the wearer observes an enlarged virtual image formed behind the image display element 10 through the light guiding member 30 by the action of the collimator optical system LC located between the intermediate image IN and the light guiding member 30.

Here, for example, there is a type of smart glass in which the image display element and the light guide member are integrated. In this type of smart glass, most of the weight is concentrated in the lens part. Therefore, when wearing the smart glasses, a large load is placed on the wearer's nose, making it difficult for the wearer to wear the smart glasses for long periods of time.

In contrast, light-guiding type smart glasses have a propagation optical system disposed between the image display element and the light-guiding member, so that the image display element and the light-guiding member are physically separated. In light-guiding type smart glasses, the image display element is built into the temple (more specifically, near the temple), for example. This distributes the load on the wearer to three points: the nose and both ears, making it easier for the wearer to wear the smart glasses for long periods of time.

As such, the propagation optical system needs to have a certain overall length in order to physically separate the image display element and the light-guiding member. At the same time, the propagation optical system is also required to have a small diameter.

In order to maintain good optical performance (wide angle of view, well-corrected aberrations, etc.) while ensuring a certain overall length and keeping the diameter of the collimator optical system LC small, the propagation optical system 20 of this embodiment is configured to form an intermediate image IN of the image light by the relay optical system RL.

The relay optical system RL is an optical system that only transfers an image. Therefore, it is not difficult to configure the relay optical system RL with a small diameter so that it can be built into the temples of smart glasses, for example. Also, by configuring the propagation optical system 20 to include a relay optical system RL, it is possible to accommodate cases where it is necessary to ensure a distance between the image display element 10 and the propagation optical system 20 for mechanical or electrical reasons, for example.

Figure 3 is a perspective view showing the schematic configuration of the light-guiding member 30. As shown in Figure 3, the light-guiding member 30 includes a first light-guiding member 31 and a second light-guiding member 32.

The image light propagated by the propagation optical system 20 is incident on the first light guiding member 31. For convenience, in FIG. 3, the image light incident from the propagation optical system 20 is denoted by the symbol L1.

A number of first mirrors 31a are arranged in the y direction inside the first light guiding member 31. The image light L1 propagated by the propagation optical system 20 is incident on the first mirror 31a that is located furthest on the negative side in the y direction among the multiple first mirrors 31a. For the sake of convenience, only six first mirrors 31a are shown in the schematic diagram of FIG. 3. In reality, the number of first mirrors 31a is greater than this.

The first mirror 31a is a mirror coated with a specific reflectance and transmittance, and reflects a portion of the incident image light L1 and transmits a portion of the image light L1. The image light L1 incident on the first light-guiding member 31 is distributed by reflection and transmission at each of the first mirrors 31a. By repeatedly distributing the image light L1 through reflection and transmission, the image light L1 becomes light that spreads in the y direction.

In the following description, for convenience, the image light that spreads in the y direction is denoted by the reference symbol L2. Also, in FIG. 3, for convenience, each ray of the image light L2 is denoted by the reference symbol L3.

The image light L2 is incident on the second light guiding member 32. A second mirror 32a and a plurality of third mirrors 32b are arranged inside the second light guiding member 32. The plurality of third mirrors 32b are arranged side by side in the x direction.

The second mirror 32a reflects the image light L2 (in other words, each light ray L3) incident from the first light guiding member 31 toward the negative side of the x direction. As a result, the image light L2 is guided in the second light guiding member 32 toward the negative side of the x direction and is incident on the third mirror 32b.

Like the first mirror 31a, the third mirror 32b is a mirror coated with a specific reflectance and transmittance, and reflects a portion of the incident image light L2 and transmits a portion of the image light L2. The image light L2 reflected by the second mirror 32a is distributed by reflection and transmission by each third mirror 32b. By repeatedly distributing the image light L2 by reflection and transmission, the image light L2 becomes light that spreads in the x direction as well as the y direction, and is emitted from the second light-guiding member 32 to the outside (specifically, toward the wearer's eye EY). Note that, for convenience, only five third mirrors 32b are shown in the schematic diagram of FIG. 3. In reality, the number of third mirrors 32b is greater than this.

In the following description, for convenience, the image light that spreads in two dimensions, the x and y directions, is denoted by the reference symbol L4. Also, in FIG. 3, for convenience, each ray of the image light L4 is denoted by the reference symbol L5. Note that, to clarify the drawing, only some of the ray L5 are denoted by the reference symbol.

When the image light L4 enters the eye EY, it is formed on the retina as a conjugate image of a virtual image. As a result, the wearer sees an enlarged virtual image of the image displayed on the image display element 10.

In this way, the light-guiding member 30 is configured to expand the eye box (the range in which the virtual image is visible) in two dimensions, the x and y directions.

The relay optical system RL has an aperture A. By disposing an aperture A within the relay optical system RL, the generation of unnecessary light is suppressed by appropriately setting the optical path within the relay optical system RL, and flare and ghosting are suppressed.

Here, the imaging position of the object, aperture A, is referred to as the "aperture imaging position P." The aperture imaging position P is the imaging position of aperture A by the optical elements included in the propagation optical system 20 that are arranged closer to the light guide member 30 than aperture A.

As shown in FIG. 1 , when an air-equivalent distance from an optical surface OP2 closest to the light guide member 30 among the optical surfaces of each optical element included in the collimator optical system LC to a diaphragm image-forming position P is defined as TLS, and a distance from an optical surface OP1 closest to the image display element 10 among the optical surfaces of each optical element included in the relay optical system RL to an optical surface OP2 is defined as TL, the propagation optical system 20 is expressed by the following formula (1):
0.0<TLS/TL<0.3...(1)
Meet the following.

When the aperture image-forming position P is closer to the light-guiding member 30 than the optical surface OP2, the spacing TLS has a positive value, and when the aperture image-forming position P is closer to the image display element 10 than the optical surface OP2, the spacing TLS has a negative value.

Near the aperture imaging position P, the on-axis chief ray and the off-axis chief ray intersect on the optical axis AX. Therefore, the effective range of the light beam (image light L1) can be made small near the aperture imaging position P. Therefore, when the above formula (1) is satisfied, the entrance portion of the first light guiding member 31 onto which the image light L1 propagated by the propagation optical system 20 is incident can be made small.

When TLS/TL exceeds the upper limit in the above formula (1), the interval TLS is too large, making it difficult to reduce the effective range of the speed of light near the entrance portion of the first light-guiding member 31. Therefore, it becomes necessary to design the entrance portion of the first light-guiding member 31 to be large.

When TLS/TL falls below the lower limit in the above formula (1), the aperture image position P is closer to the image display element 10 than the optical surface OP2, making it difficult to reduce the effective range of the speed of light near the entrance portion of the first light guiding member 31. Therefore, it becomes necessary to design the entrance portion of the first light guiding member 31 to be large.

It is more preferable that the propagation optical system 20 satisfies the following formula (2).
0.0<TLS/TL<0.2...(2)

The relay optical system RL is composed of a front group G1 and a rear group G2 arranged in that order from the image display element 10 side toward the light guide member 30 side. Here, the widest gap between the optical elements included in the relay optical system RL is designated by the symbol TLRa. The front group G1 is composed of optical elements arranged on the image display element 10 side of the gap TLRa. The rear group G2 is composed of optical elements arranged on the light guide member 30 side of the gap TLRa.

By appropriately setting the distance TLRa, it is possible to set the overall length of the propagation optical system 20 to an appropriate length (in the example of smart glasses, a length that allows the image display element 10 to be placed at the temple (near the temple) as described above) while effectively correcting various aberrations.

As shown in FIG. 2, aperture A is disposed between the front group G1 and the rear group G2 (in other words, the distance TLRa). Note that the position of aperture A is not limited to between the front group G1 and the rear group G2. As shown in Numerical Example 3 or 4 described later, aperture A may be disposed within the front group G1.

By placing aperture A near or within front group G1, it is possible to effectively correct various aberrations while keeping the diameter of the relay optical system RL small.

When the total length of the relay optical system RL is TLR, the propagation optical system 20 is expressed by the following formula (3):
0.3<TLRa/TLR<0.6...(3)
It is desirable to satisfy the following.

When TLRa/TLR exceeds the upper limit in the above formula (3), the proportion of the distance TLRa between the front group G1 and the rear group G2 in the total length of the relay optical system RL becomes too large, and the space for arranging the front group G1 and the rear group G2 becomes small, making it difficult to effectively correct various aberrations.

When TLRa/TLR falls below the lower limit in the above formula (3), the distance TLRa between the front group G1 and the rear group G2 becomes too small, making it difficult to satisfactorily correct various aberrations within the relay optical system RL while maintaining the overall length of the propagation optical system 20.

Preferably, the front group G1 is composed of a positive lens L11, a negative lens L12, and a positive lens L13 arranged in this order from the image display element 10 side toward the light guide member 30 side.

By configuring the front group G1 in this way, chromatic aberration can be effectively corrected, and in particular spherical aberration and coma aberration can be effectively corrected. In order to effectively correct aberrations, it is desirable to configure each lens surface of the positive lens L11, the negative lens L12, and the positive lens L13 with an aspheric surface.

Preferably, the rear group G2 is composed of a positive lens L21 and a negative lens L22 arranged in this order from the image display element 10 side toward the light guide member 30 side.

By configuring the rear group G2 in this way, the remaining aberrations in the front group G1 and the collimator optical system LC can be corrected with two lenses, one positive and one negative, and various aberrations can be suppressed even better. In order to correct aberrations better, it is desirable to configure each lens surface of the positive lens L21 and the negative lens L22 with an aspheric surface.

When the distance from the optical surface OP1 to the diaphragm A is TLA and the diagonal length of the image display area of the image display element 10 is Y, the propagation optical system 20 is expressed by the following formula (4):
2<TLA/Y<5...(4)
It is desirable to satisfy the following.

Here, the image light emitted from the image display element 10 is strongest when it is parallel to the optical axis AX. Therefore, the more light the propagation optical system 20 can take in, the more light it can take in. By satisfying the above formula (4), the propagation optical system 20 can take in more light (especially light parallel to the optical axis AX) while keeping the diameter of the relay optical system RL small.

When TLA/Y exceeds the upper limit in the above formula (4), the distance from the image display element 10 to the aperture A becomes too large, making it difficult for the propagation optical system 20 to take in a large amount of light while keeping the diameter of the relay optical system RL small.

When TLA/Y in the above formula (4) falls below the lower limit, the angle of the off-axis chief ray with respect to the optical axis AX becomes too large, making it difficult to capture a large amount of peripheral light.

When the size of the diagonal opening of the diaphragm A is AP, the propagation optical system 20 is expressed by the following equation (5):
0.5<AP/Y<2.0...(5)
It is desirable to satisfy the following.

When AP/Y exceeds the upper limit in the above formula (5), the aperture A becomes too large, making it difficult to keep the diameter of the relay optical system RL small.

If AP/Y falls below the lower limit in the above formula (5), the aperture A becomes too small, making it difficult for the propagation optical system 20 to capture a large amount of light.

When the lateral magnification of the relay optical system RL is β_relay, the propagation optical system 20 is expressed by the following equation (6):
-2.0<β_relay<-1.0...(6)
It is desirable to satisfy the following.

When the image display area of the image display element 10 becomes larger, electrical system components such as the PCB (Printed Circuit Board) also become larger, making miniaturization difficult. On the other hand, to widen the angle of view, the intermediate image IN needs to be relatively large. From this perspective, the above formula (6) specifies the preferred range of the lateral magnification β_relay of the relay optical system RL.

The collimator optical system LC is composed of a lens L31 and a lens L32 arranged in this order from the image display element 10 side toward the light guide member 30 side. As explained above, the propagation optical system 20 is composed of a relay optical system RL and a collimator optical system LC.

By configuring the propagation optical system 20 with a relay optical system RL and a collimator optical system LC, it is possible to effectively correct various aberrations even though the collimator optical system LC has a simple configuration (specifically, a two-element configuration).

When the lens L31 is a positive lens, the focal length of the collimator optical system LC is fc, and the focal length of the lens L31 is fc1, the propagation optical system 20 is expressed by the following formula (7):
0.5<fc1/fc<1.0...(7)
It is desirable to satisfy the following.

If the above formula (7) is not satisfied, it becomes difficult to effectively correct various aberrations while positioning the aperture image position P at an appropriate position.

Next, specific numerical examples 1 to 4 of the propagation optical system 20 are shown. The common points between numerical examples 1 to 4 are as follows:

<Common features of Numerical Examples 1 to 4>
Diagonal length Y: 6 mm
Numbers 1 and 2 on the front: Surfaces of the image display element 10 (number 2 is the pixel array surface)
Table numbers 3 to 13: optical surfaces of the optical elements of the relay optical system RL. Table numbers 14 to 17: optical surfaces of the optical elements of the collimator optical system LC. Table numbers 18 to 19: parallel plate (specifically, light guiding member 30).
Eye relief: 15mm
Aberration diagram: Calculated when imaging with an ideal lens with a focal length of 17 mm

[Numerical Example 1]
4 is a diagram showing an optical configuration of the propagation optical system 20 according to the first numerical embodiment of the present invention. As shown in FIG. 4, the propagation optical system 20 is configured by arranging a relay optical system RL and a collimator optical system LC in order from the image display element 10 side. The front group G1 of the relay optical system RL is configured by arranging, in order from the image display element 10 side, a meniscus lens (positive lens L11) convex on the light guide member 30 side, a biconcave lens (negative lens L12), and a biconvex lens (positive lens L13). The rear group G2 of the relay optical system RL is configured by arranging, in order from the image display element 10 side, a meniscus lens (positive lens L21) convex on the light guide member 30 side, and a biconcave lens (negative lens L22). The diaphragm A is disposed between the front group G1 and the rear group G2 (in other words, the interval TLRa). The collimator optical system LC is composed of, in order from the image display element 10 side, a biconvex lens (lens L31) having positive power and a meniscus lens (lens L32) having positive power and convex toward the light guide member 30 side.

The specific numerical configuration of the propagation optical system 20 according to Numerical Example 1 is shown in Table 1. The numbers in Table 1 are given to each surface of the image display element 10, the propagation optical system 20, and the light guide member 30, in order from the image display element 10 side. In Table 1, R (unit: mm) indicates the radius of curvature of each surface of the optical element, D (unit: mm) indicates the thickness of the optical element on the optical axis or the spacing between the optical elements, Nd indicates the refractive index of the d-line (wavelength 587.56 nm), and νd indicates the Abbe number of the d-line. The product name and manufacturer of the material of the optical element are written to the right of the Abbe number. In Numerical Example 1, the diagonal angle of view of the virtual image is 40.5 degrees, and the maximum object height is 3 mm.

[Table 1]

In Table 1, the surfaces marked with a number "*" are aspheric. Table 2 shows the data for each aspheric surface. In Table 2, the label E indicates a power with 10 as the base and the number to the right of E as the exponent. The radius of curvature R of the aspheric element indicates the radius of curvature on the optical axis (paraxial radius of curvature). The aspheric shape is expressed by the following formula, where Z is the sag amount, C is the paraxial curvature (1/R), h (unit: mm) is the height from the optical axis, K is the conic coefficient, and A ₄ , A ₆ , ... are aspheric coefficients of even orders of 4th or higher.

Z＝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

The table format is the same for the following numerical examples 2 to 4.

[Table 2]

Figure 5 shows various aberration diagrams (spherical aberration, astigmatism, and distortion) of the propagation optical system 20 according to Numerical Example 1. The spherical aberration diagram in Figure 5 shows spherical aberration at the d-line and g-line (435.84 nm). The solid line shows spherical aberration at the d-line, and the dotted line shows spherical aberration at the g-line. The astigmatism diagram in Figure 5 shows astigmatism at the d-line (i.e., the difference between the sagittal image surface and the meridional image surface). The solid line shows aberration in the sagittal direction, and the dashed line shows aberration in the meridional direction. The vertical axis of the spherical aberration diagram and the astigmatism diagram shows the image height, and the horizontal axis shows the amount of aberration. The vertical axis of the distortion diagram in Figure 5 shows the image height, and the horizontal axis shows the distortion rate at the d-line.

Figure 6 is a diagram of lateral aberration of the propagation optical system 20 according to Numerical Example 1. The diagram of lateral aberration shows the lateral aberration at the d-line and the g-line at each image height. The solid line shows the lateral aberration at the d-line, and the dotted line shows the lateral aberration at the g-line. The lateral aberration is measured in the X and Y directions. The left diagram of Figure 6 (the diagram with "Y-FAN" added to the upper column) shows the lateral aberration in the Y direction, and the right diagram of Figure 6 (the diagram with "X-FAN" added to the upper column) shows the lateral aberration in the X direction.

As described below, in Numerical Example 1, all of the above expressions (1) to (7) are satisfied.
TLS/TL: 0.11 (see equations (1) and (2))
TLRa/TLR: 0.46 (see formula (3))
TLA/Y: 3.81 (see formula (4))
AP/Y: 1.00 (see formula (5))
β_relay: -1.46 (see formula (6))
fc1/fc: 0.79 (see formula (7))

The propagation optical system 20 according to Numerical Example 1 satisfactorily corrects various aberrations (see Figures 5 and 6), while ensuring a wide angle of view (a diagonal angle of view exceeding 40 degrees), thereby achieving good image performance. Furthermore, the propagation optical system 20 according to Numerical Example 1 achieves various effects by satisfying the above expressions (1) to (7).

[Numerical Example 2]
7 is a diagram showing the optical configuration of the propagation optical system 20 according to Numerical Example 2 of the present invention. As shown in FIG. 7, the shape type (i.e., "biconcave", "biconvex", "meniscus", etc.) of each lens arranged in the propagation optical system 20 according to Numerical Example 2 is the same as that in Numerical Example 1. The specific numerical configuration of the propagation optical system 20 according to Numerical Example 2 is shown in Table 3. The data of each aspheric surface in Numerical Example 2 is shown in Table 4. In Numerical Example 2, the diagonal angle of view of the virtual image is 50.4 degrees, and the maximum object height is 3 mm.

[Table 3]

[Table 4]

Figure 8 shows various aberration diagrams (spherical aberration, astigmatism, and distortion) of the propagation optical system 20 according to Numerical Example 2. Figure 9 shows lateral aberration diagrams of the propagation optical system 20 according to Numerical Example 2.

As described below, in the second numerical example, all of the above formulas (1) to (7) are satisfied.
TLS/TL: 0.09 (see equations (1) and (2))
TLRa/TLR: 0.48 (see formula (3))
TLA/Y: 3.68 (see formula (4))
AP/Y: 1.17 (see formula (5))
β_relay: -1.52 (see formula (6))
fc1/fc: 0.88 (see formula (7))

In the propagation optical system 20 according to Numerical Example 2, various aberrations are also well corrected (see FIGS. 8 and 9), a wide angle of view (particularly an angle of view exceeding 50 degrees in the diagonal direction) is ensured, and good image performance is achieved. In addition, in the propagation optical system 20 according to Numerical Example 2, various effects are achieved by satisfying the above expressions (1) to (7).

[Numerical Example 3]
FIG. 10 is a diagram showing the optical configuration of the propagation optical system 20 according to the numerical example 3 of the present invention. As shown in FIG. 10, in the numerical example 3, the positive lens L11 and the positive lens L21 are biconvex lenses. In the numerical example 3, the shape type of each lens other than the positive lens L11 and the positive lens L21 is the same as that of the numerical example 1. In the numerical example 3, the aperture A is disposed in the front group G1 (specifically, between the negative lens L12 and the positive lens L13). The specific numerical configuration of the propagation optical system 20 according to the numerical example 3 is shown in Table 5. The data of each aspheric surface in the numerical example 3 is shown in Table 6. In the numerical example 3, the angle of view in the diagonal direction of the virtual image is 40.3 degrees, and the maximum object height is 3 mm.

[Table 5]

[Table 6]

Figure 11 shows various aberration diagrams (spherical aberration, astigmatism, and distortion) of the propagation optical system 20 according to Numerical Example 3. Figure 12 shows lateral aberration diagrams of the propagation optical system 20 according to Numerical Example 3.

As described below, in Numerical Example 3, all of the above formulas (1) to (7) are satisfied.
TLS/TL: 0.10 (see equations (1) and (2))
TLRa/TLR: 0.45 (see formula (3))
TLA/Y: 3.28 (see formula (4))
AP/Y: 0.93 (see formula (5))
β_relay: -1.34 (see formula (6))
fc1/fc: 0.81 (see formula (7))

In the propagation optical system 20 according to Numerical Example 3, various aberrations are also well corrected (see FIGS. 11 and 12), a wide angle of view (a diagonal angle of view exceeding 40 degrees) is ensured, and good image performance is achieved. In addition, in the propagation optical system 20 according to Numerical Example 3, various effects are achieved by satisfying the above expressions (1) to (7).

[Numerical Example 4]
FIG. 13 is a diagram showing an optical configuration of the propagation optical system 20 according to the numerical example 4 of the present invention. As shown in FIG. 13, in the numerical example 4, the positive lens L11 is a biconvex lens. In the numerical example 4, the shape type of each lens other than the positive lens L11 is the same as that of the numerical example 1. Also, in the numerical example 4, as in the numerical example 3, the aperture A is disposed between the negative lens L12 and the positive lens L13. The specific numerical configuration of the propagation optical system 20 according to the numerical example 4 is shown in Table 7. The data of each aspheric surface in the numerical example 4 is shown in Table 8. In the numerical example 4, the angle of view in the diagonal direction of the virtual image is 45.4 degrees, and the maximum object height is 3 mm.

[Table 7]

[Table 8]

Figure 14 shows various aberration diagrams (spherical aberration, astigmatism, and distortion) of the propagation optical system 20 according to Numerical Example 4. Figure 15 shows lateral aberration diagrams of the propagation optical system 20 according to Numerical Example 4.

As described below, in Numerical Example 4, all of the above formulas (1) to (7) are satisfied.
TLS/TL: 0.11 (see equations (1) and (2))
TLRa/TLR: 0.44 (see formula (3))
TLA/Y: 2.79 (see formula (4))
AP/Y: 0.93 (see formula (5))
β_relay: -1.23 (see formula (6))
fc1/fc: 0.81 (see formula (7))

In the propagation optical system 20 according to Numerical Example 4, various aberrations are also well corrected (see FIGS. 14 and 15), a wide angle of view (a diagonal angle of view exceeding 40 degrees) is ensured, and good image performance is achieved. In addition, in the propagation optical system 20 according to Numerical Example 4, various effects are achieved by satisfying the above expressions (1) to (7).

The above is an explanation of exemplary embodiments of the present invention. The embodiments of the present invention are not limited to those described above, and various modifications are possible within the scope of the technical concept of the present invention. For example, the embodiments of the present application also include appropriate combinations of embodiments explicitly shown as examples in the specification or obvious embodiments.

1: Head-mounted display 10: Image display element 20: Propagation optical system 30: Light guide member 31: First light guide member 31a: First mirror 32: Second light guide member 32a: Second mirror 32b: Third mirror A: Diaphragm G1: Front group G2: Rear group LC: Collimator optical system RL: Relay optical system

Claims (12)

In a propagation optical system that propagates light from an image display element that displays an image to a light guiding member of a virtual image display device,
a first optical system 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 the image is formed between the first optical system and the second optical system,
A stop is disposed in the first optical system,
When an image-forming position of the aperture, which is an object, by an optical element included in the propagation optical system that is disposed closer to the light-guiding member than the aperture is defined as an aperture image-forming position, an air-equivalent distance from an optical surface of each optical element included in the second optical system that is closest to the light-guiding member to the aperture image-forming position is defined as TLS, and a distance from an optical surface of each optical element included in the first optical system that is closest to the image display element to an optical surface of each optical element included in the second optical system that is closest to the light-guiding member is defined as TL, the following formula is satisfied: 0.0<TLS/TL<0.3
Fulfilling
Propagation optics. the first optical system includes a front group and a rear group arranged in this order from the image display element side to the light guide member side,
the front group includes an optical element disposed closer to the image display element than the widest interval among the intervals between the optical elements included in the first optical system,
the rear group is made up of optical elements disposed closer to the light guide member than the widest interval,
the diaphragm is disposed within the front group or between the front group and the rear group;
The transmission optical system according to claim 1 . When the total length of the first optical system is TLR and the widest interval is TLRa, the following formula is satisfied: 0.3<TLRa/TLR<0.6
Fulfilling
The transmission optical system according to claim 2 . the front group includes, in order from the image display element side to the light guide member side, a positive lens, a negative lens, and a positive lens.
The propagation optical system according to claim 2 or 3. the rear group includes a positive lens and a negative lens arranged in this order from the image display element side to the light guide member side.
The propagation optical system according to claim 2 . When the distance from the optical surface of each optical element included in the first optical system that is closest to the image display element to the diaphragm is TLA and the diagonal length of the image display element is Y, the following formula 2<TLA/Y<5 is satisfied.
Fulfilling
The propagation optical system according to claim 1 . When the size of the diagonal opening of the diaphragm is AP and the diagonal length of the image display element is Y, the following formula is satisfied: 0.5<AP/Y<2.0
Fulfilling
The propagation optical system according to claim 1 . When the lateral magnification of the first optical system is β_relay, the following formula is satisfied: −2.0<β_relay<−1.0
Fulfilling
The propagation optical system according to claim 1 . the first optical system is a relay optical system,
the second optical system is a collimator optical system,
The second optical system is configured by disposing two lenses.
The propagation optical system according to claim 1 . a lens of the second optical system disposed on the image display element side is a positive lens,
When the focal length of the second optical system is fc and the focal length of the positive lens disposed on the image display element side is fc1, the following formula is satisfied: 0.5<fc1/fc<1.0
Fulfilling
The transmission optical system according to claim 9 . an image display element for displaying an image;
A propagation optical system according to claim 1 , which propagates light from the image display element;
a light guide member that guides the light propagated by the propagation optical system and outputs the light for displaying a virtual image;
Equipped with
Virtual image display device. The virtual image display device according to claim 11,
Head-mounted display.