Eyepiece lens and display unit

An eyepiece lens includes: a first lens having positive refractive power, the first lens having a convex surface that faces toward an eye point side; and a second lens having positive refractive power, the second lens having a convex surface that faces toward the eye point side. The first and second lenses are arranged in order from the eye point side. Following conditional expressions are satisfied,3.0>(h×ω)1/2/E>1.2  (1)2.3>(L−E)/h>1.5  (2)where h is a height of the image at a horizontal end, ω is a half angle of view in a horizontal direction, E is a distance from an eye point to the first lens, the distance being an eye relief, and L is a distance from the eye point to the image.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Priority Patent Application JP 2013-108669 filed May 23, 2013, the entire contents of each which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to an eyepiece lens that magnifies an image (such as an image displayed on an image display device), and to a display unit suitable as a unit such as a head-mounted display that uses such an eyepiece lens.

As an display unit that uses an image display device, an electronic view finder, an electronic binocular, a head-mounted display, etc. are known.

SUMMARY

In a head-mounted display, in particular, it is desired that an eyepiece optical system and a main body of a display unit are compact and light in weight since the main body of the display unit is worn in front of one's eyes and are used for a long time. However, it is necessary to allow an angle of view to be wide in order to create a sense of immersion so that a user is drawn into an image or a picture. Therefore, glass has been used for the eyepiece optical system in some cases. Also, a plurality of pieces of glass that have different refractive indices and dispersion characteristics have been used in some cases in order to correct aberration, in particular, chromatic aberration. In such cases, it is possible to achieve favorable optical performance and to create a high sense of immersion while securing a wide angle of view. However, a user wears the heavy eyepiece optical system and the heavy main body of the display unit in front of his or her eyes due to the use of glass. A long-time use of such eyepiece optical system and display unit causes the user to be extremely tired.

Eyepiece optical systems disclosed in Japanese Unexamined Patent Application Publication Nos. 2005-134867 and 2009-145909 each use a plurality of pieces of glass to achieve a wide angle of view. A plurality of pieces of glasses having different refractive indices and different dispersion characteristics are used to favorably correct various aberrations such as chromatic aberration. By thus presenting a clear image, a high sense of immersion is successfully created. However, these eyepiece optical systems are extremely heavy due to the use of many pieces of glasses. Therefore, a long-time use of such eyepiece optical systems may cause symptoms that damage one's health such as fatigue in neck or shoulder. Further, the use of many pieces of expensive glass leads to high cost. Accordingly, it is difficult to provide such eyepiece optical systems to customers at a price which is easy to afford.

An eyepiece optical system disclosed in Japanese Unexamined Patent Application Publication No. 2010-266776 uses many resin lenses, and therefore it may be considered to be light in weight. Therefore, it may be considered that such an eyepiece optical system does not damage one's health even if being worn for a long time, and has superior wearing characteristics. It may be considered that the eyepiece optical system favorably corrects aberrations, has high performance as an optical system, and achieves favorable view of an image. However, this eyepiece optical system is not favorable to secure a wide angle of view. Therefore, it is difficult to create a high sense of immersion.

Accordingly, it is desired to develop an eyepiece optical system that is manufactured at low cost, magnifies an image on the image display device as large as possible, creates a high sense of immersion by achieving a wide angle of view which is important for a head-mounted display, has light weight, has favorable wearing characteristics, and does not cause a user to be tired even if being used for a long time. It is also desired to develop a display unit that uses such an eyepiece optical system.

It is desirable to provide an eyepiece lens and a display unit that are capable of magnifying an image with a wide angle of view, and of achieving performance suitably used for a unit such as a head-mounted display.

According to an embodiment of the present disclosure, there is provided an eyepiece lens including: a first lens having positive refractive power, the first lens having a convex surface that faces toward an eye point side; and a second lens having positive refractive power, the second lens having a convex surface that faces toward the eye point side. The first and second lenses are arranged in order from the eye point side. Following conditional expressions are satisfied,
3.0>(h×ω)1/2/E>1.2  (1)
2.3>(L−E)/h>1.5  (2)
where h is a height of the image at a horizontal end, ω is a half angle of view in a horizontal direction, E is a distance from an eye point to the first lens, the distance being an eye relief, and L is a distance from the eye point to the image.

According to an embodiment of the present disclosure, there is provided a display unit including: an image display device; and an eyepiece lens configured to allow an image displayed on the image display device to be magnified. The eyepiece lens includes: a first lens having positive refractive power, the first lens having a convex surface that faces toward an eye point side; and a second lens having positive refractive power, the second lens having a convex surface that faces toward the eye point side. The first and second lenses are arranged in order from the eye point side. Following conditional expressions are satisfied,
3.0>(h×ω)1/2/E>1.2  (1)
2.3>(L−E)/h>1.5  (2)
where h is a height of the image at a horizontal end, ω is a half angle of view in a horizontal direction, E is a distance from an eye point to the first lens, the distance being an eye relief, and L is a distance from the eye point to the image.

In the eyepiece lens and the display unit according to the above-described embodiments of the present disclosure, the first and second lenses are arranged in order from the eye point side, and the configurations of the respective lenses are optimized. This allows an image to be magnified with a wide angle of view. Accordingly, it is possible to achieve performance that is suitably used for a unit such as a head-mounted display.

According to the eyepiece lens and the display unit according to the above-described embodiments of the present disclosure, the first and second lenses are arranged in order from the eye point side, and the configurations of the respective lenses are optimized. Therefore, an image is allowed to be magnified with a wide angle of view. Accordingly, it is possible to achieve performance that is suitably used for a unit such as a head-mounted display.

It is to be noted that the effects disclosed in the present specification are mere examples, and the effect of the embodiment of the present disclosure is not limited thereto. Also, the embodiment of the present disclosure may have additional effects.

DETAILED DESCRIPTION

An embodiment of the present disclosure will be described below in detail referring to the drawings. The description will be provided in the following order.

1. Basic Configuration of Lens

2. Functions and Effects

3. Example of Application to Display Unit

4. Numerical Examples of Lenses

5. Other Embodiments

1. Basic Configuration of Lens

FIG. 1illustrates a first configuration example of an eyepiece lens according to an embodiment of the present disclosure. This configuration example corresponds to a configuration of a lens in Numerical example 1 which will be described later. A configuration of the eyepiece lens according to the present embodiment will be appropriately described below in correspondence with the configuration example shown inFIG. 1. However, the technology of the present disclosure is not limited to the configuration examples illustrated in the drawings.

The eyepiece lens according to the present embodiment is substantially configured of two lenses that are a first lens L1and a second lens L2arranged in order from an eye point E.P. side along an optical axis Z1.

This eyepiece lens may be applicable, for example, as an eyepiece optical system in a display unit such as a head-mounted display200(FIGS. 41 and 42) which will be described later. In a case where this eyepiece lens is applied to the display unit such as the head-mounted display200, this eyepiece lens is used for magnifying an image displayed on an image display device100such as an LCD (Liquid Crystal Display) and an organic EL display as shown inFIG. 1. A component such as a sealant glass for protecting the image display device100may be arranged on a front surface of the image display device100.

The eye point E.P. corresponds to a position of a pupil of a viewer, and serves also as an aperture stop STO. The first lens L1has positive refractive power, and has a convex surface facing toward the eye point E.P. side. The second lens L2has positive refractive power, and has a convex surface facing toward the eye point E.P. side.

An image-sided surface of the first lens L1and an image-sided surface of the second lens L2each may desirably have an aspherical shape. The eye-point-E.P.-sided surface of the first lens L1may desirably have an aspherical shape that has an inflection point. The first lens L1and the second lens L2each may desirably be configured of a material that has a linear expansion coefficient of 20×10−6/° C. or larger.

In addition to the above, the eyepiece lens according to the present embodiment may desirably satisfy predetermined conditional expressions etc. which will be described later.

2. Functions and Effects

Next, description will be given of functions and effects of the eyepiece lens according to the present embodiment.

According to the eyepiece lens of the present embodiment, the first lens L1closer to the eye point E.P. is a convex lens that has a convex surface facing toward the eye point E.P. side, as a basic configuration. Therefore, it is possible to secure a wide angle of view for creating a high sense of immersion. Also, the second lens L2closer to the image display device100is a convex lens that has a convex surface facing toward the eye point E.P. side, as the basic configuration. Therefore, the second lens L2in combination with the first lens L1allows an image to be further magnified. Therefore, a wide angle of view is secured.

Moreover, by allowing the image-sided surface of the first lens L1and the image-sided surface of the second lens L2to have aspherical shapes as a preferable configuration, aberration, in particular, comma aberration is favorably corrected with a small number of lenses. Also, even when a position of one's eye moves with respect to the optical axis Z1during viewing, for example, even when a viewing position shifts in a lateral or vertical direction, the image on the image display device100is not disturbed much. Thus, such a configuration contributes to securing favorable visibility. In particular, the aspherical shape of the image-sided surface of the second lens L2allows a light ray from the image display device100to enter the optical system at an angle which is not so large. As a result, color shift which may be caused by a color filter in the image display device100is prevented. Thus, such a configuration contributes to favorably magnifying an image or a picture with less color shift.

By allowing the eye-point-E.P.-sided surface of the first lens L1to have an aspherical shape that has an inflection point as a preferable configuration, it is possible to favorably correct occurrence of aberration in a case where the position of one's eye moves with respect to the optical axis Z1during viewing. Therefore, such a configuration contributes to securing favorable visibility without causing the image on the image display device100to be disturbed much even when the position of one's eye moves during the viewing.

Moreover, by favorably configuring each of the first lens L1and the second lens L2of the material having a linear expansion coefficient of 20×10−6/° C., it is possible to provide an extremely-light eyepiece lens that is less likely to cause a user to be tired even with wearing the eyepiece lens in front of one's eyes for a long time, and that largely magnifies the image from the image display device100and secures a wide angle of view.

The eyepiece lens according to the present embodiment achieves more favorable performance by optimizing the configurations of the respective lenses so as to satisfy at least one, preferably, two or more in combination, of the following conditional expressions.
3.0>(h×ω)1/2/E>1.2  (1)

In the above-described Conditional expression (1), h is a height of the image at a horizontal end (seeFIG. 1), ω is a half angle of view in a horizontal direction, and E is a distance (an eye relief) from the eye point E.P. to the first lens L1(seeFIG. 1).

It is to be noted that, when the eyepiece lens according to the present embodiment is applied to a display unit such as the head-mounted display200(FIGS. 41 and 42) which will be described later, h is a height at a horizontal end of an image displayed on the image display device100. For example, when the image display device100has a quadrangular shape, a maximum height of the image is a height h′ at a diagonal end. The height h at the horizontal end has a value smaller than that of the height h′ at the diagonal end as shown inFIG. 1. The height h at the horizontal end is used in the conditional expressions taking into consideration visibility in a case where the eyepiece lens is applied to a display unit such as the head-mounted display200.

Conditional expression (1) shows a relationship of the horizontal half angle of view ω and the eye relief E with respect to the height h at the horizontal end of the image, based on the above-described basic configuration. Basically, as the image to be magnified is larger, it is easier to secure a wide angle of view. Also, as the distance between the eye point E.P. and the first lens L1is shorter, it is easier to secure a wide angle of view as well. Specifically, when a value of (h×ω)1/2/E is smaller than the range shown in Conditional expression (1), it is difficult to achieve a wide angle of view while keeping favorable quality of image. This may lead, for example, to loss of attractiveness as the display unit in the case where the eyepiece lens is applied to the head-mounted display. When the value of (h×ω)1/2/E is larger than the range shown in Conditional expression (1), the distance between the eye point E.P. and the first lens L1becomes excessively short. This may lead, for example, to degradation in wearing characteristics in the case where the eyepiece lens is applied to the head-mounted display. For example, this may set a condition in wearing the head-mounted display. Examples of such a condition may include that the head-mounted display is unwearable when the viewer wears eyeglasses.

It is to be noted that the numerical range of Conditional expression (1) may be preferably set as in following Conditional expression (1)′ in order to achieve a wide angle of view while keeping more favorable quality of image.
2.6>(h×ω)1/2/E>1.4  (1)′
2.3>(L−E)/h>1.5  (2)

In the above-described Conditional expression (2), L is a distance from the eye point E.P. to the image (seeFIG. 1).

Conditional expression (2) shows a relationship of a value obtained by subtracting a length of the eye relief E from a total length L of the optical system with respect to the height h at the horizontal end of the image, based on the above-described basic configuration. When a value of (L−E)/h is larger than the range shown in Conditional expression (2), the length from the eye-point-E.P.-sided surface of the first lens L1to the image display device100becomes long. Therefore, although aberration is favorably corrected, for example, in the case where the eyepiece lens is applied to the head-mounted display, the head-mounted display becomes too long to wear in front of one's eyes. Thus, such a configuration degrades wearing characteristics. Also, in such a configuration, the image display device100which is a weight object is located in a position away from one's eyes. Therefore, a moment originating on the position of one's eye is caused, which further degrades the wearing characteristics. When the value of (L−E)/h is smaller than the range shown in Conditional expression (2), the above-described point is improved and the wearing characteristics are improved. However, in reverse, it becomes difficult to correct aberration by the optical system, and therefore, optical performance is degraded. As a result, for example, in the case where the eyepiece lens is applied to the head-mounted display, it is difficult to create a sense of immersion with a clear image.

It is to be noted that the numerical range of Conditional expression (2) may be preferably set as in following Conditional expression (2)′ in order to achieve more favorable wearing characteristics and high optical performance.
2.1>(L−E)/h>1.7  (2)′
3.7>(f1×f2)1/2/f>1.4  (3)

In the above-described Conditional expression (3), f is a total focal length, f1is a focal length of the first lens L1, and f2is a focal length of the second lens L2.

Conditional expression (3) shows a relationship of the focal length f1of the first lens L1and the focal length f2of the second lens L2with respect to the total focal length f of this eyepiece lens. When a value of (f1×f2)1/2/f is larger than the range shown in Conditional expression (3), power of one of the first lens L1and the second lens L2becomes excessively weak. Therefore, it is difficult to maintain the wide angle of view. For example, when the eyepiece lens is applied to the head-mounted display, it may be desirable to allow distortion to occur in some degrees, and to create an aggregation-like state around the center of the screen to create a high-resolution-like state. When the value of (f1×f2)1/2/f is smaller than the range shown in Conditional expression (3), the power of the first lens L1becomes excessively close to the power of the second lens L2. Therefore, it is difficult to create the aggregation-like state around the center of the screen and to create a high-resolution-like state.

It is to be noted that the numerical range of Conditional expression (3) may be preferably set as in following Conditional expression (3)′ in order to achieve higher optical performance.
3.3>(f1×f2)1/2/f>1.7  (3)′
40>|(R3+R5)/(R3−R5)|  (4)

In the above-described Conditional expression (4), R3is a paraxial curvature radius of the image-sided surface of the first lens L1, and R5is a paraxial curvature radius of the image-sided surface of the second lens L2.

Conditional expression (4) shows a relationship between the paraxial curvature radius R3of the image-sided surface of the first lens L1and the paraxial curvature radius R5of the image-sided surface of the second lens L2. By allowing Conditional expression (4) to be satisfied, various aberrations, in particular, Petzval sum is adjusted, and astigmatism is corrected.

It is to be noted that the numerical range of Conditional expression (4) may be preferably set as in following Conditional expression (4)′ in order to achieve higher optical performance.
35>|(R3+R5)/(R3−R5)|  (4)′
1.9>R4/f2>0.4  (5)

In the above-described Conditional expression (5), R4is a paraxial curvature radius of the eye-point-E.P.-sided surface of the second lens L2.

Conditional expression (5) shows a relationship of the focal length f2of the second lens L2with respect to the paraxial curvature radius R2of the eye-point-E.P.-sided surface of the second lens L2. By allowing Conditional expression (5) to be satisfied, it is possible to correct aberration and secure a wide angle of view while securing favorable visibility without allowing the power of the second lens L2to be so strong. When a value of R4/f2is larger than the upper limit in Conditional expression (5), the power of the second lens L2becomes excessively strong. Therefore, although a wide angle of view is secured, error sensitivity with respect to manufacturing error becomes high due to the strong power, which leads to degradation in manufacturing characteristics. When the value of R4/f2is smaller than the lower limit in Conditional expression (5), the power of the second lens L2becomes excessively weak. Therefore, it is difficult to keep the wide angle of view. Also, it is difficult to create the aggregation-like state in the screen by allowing distortion to be occurred.

It is to be noted that the numerical range of Conditional expression (5) may be preferably set as in following Conditional expression (5)′ in order to achieve higher optical performance.
1.8>R4/f2>0.6  (5)′
1.0>R2/f1>0.1  (6)

In the above-described Conditional expression (6), R2is a paraxial curvature radius of the eye-point-E.P.-sided surface of the first lens L1.

Conditional expression (6) shows a relationship of the focal length f1of the first lens L1with respect to the paraxial curvature radius of the eye-point-E.P.-sided surface of the first lens L1. When a value of R2/f1is larger than the upper limit of Conditional expression (6), the power of the first lens L1becomes excessively strong. Therefore, error sensitivity with respect to manufacturing error becomes high, which leads to degradation in manufacturing characteristics. When the value of R2/f1is smaller than the lower limit of Conditional expression (6), the power of the first lens L1becomes excessively weak. Therefore, it is difficult to correct aberration. In particular, when the position of one's eye moves with respect to the optical axis Z1during viewing, for example, when the viewing position shifts in the lateral or vertical direction, visibility is degraded as a result.

It is to be noted that the numerical range of Conditional expression (6) may be preferably set as in following Conditional expression (6)′ in order to achieve higher optical performance.
0.8>R2/f1>0.19  (6)′
1.2>(D2+D4)/(D3+D5)>0.2  (7)

In the above-described Conditional expression (7), D2is a central thickness of the first lens L1, D3is a spacing between the first lens L1and the second lens L2, D4is a central thickness of the second lens L2, and D5is a spacing between the second lens L2and the image.

Conditional expression (7) shows a relationship of the spacing D3between the first lens L1and the second lens L2and the spacing D5between the second lens L2and the image, that are thicknesses (D3and D5) of air lenses, with respect to the central thickness D2of the first lens L1and the central thickness D4of the second lens L2. When a value of (D2+D4)/(D3+D5) is larger than the upper limit in Conditional expression (7), the central thickness D2of the first lens L1and the central thickness D4of the second lens L2become excessively thick. As a result, weight of the optical system increases. Due to the heavy weight of the optical system, for example, in a case where the eyepiece lens is applied to the head-mounted display, the wearing characteristics are degraded as a result. When the value of (D2+D4)/(D3+D5) is smaller than the lower limit in Conditional expression (7), the thickness of the first lens L1or the second lens L2, or both become excessively thin. Therefore, the power is not allowed to be sufficiently strong to keep the wide angle of view. As a result, the wide angle of view and the high sense of immersion are degraded.

It is to be noted that the numerical range of Conditional expression (7) may be preferably set as in following Conditional expression (7)′ in order to achieve higher optical performance.
1.0>(D2+D4)/(D3+D5)>0.4  (7)′

As described above, according to the present embodiment, it is possible to magnify the image on the image display device100as large as possible at low cost. Also, for example, it is possible to achieve an eyepiece optical system that is light in weight, has favorable wearing characteristics, and does not allow a user to be tired even with long-time use, while achieving a wide angle of view and creation of a high sense of immersion which are important, for example, in a case where the eyepiece optical system is applied to a unit such as the head-mounted display.

3. Example of Application to Display Unit

FIGS. 41 and 42illustrate a configuration example of the head-mounted display200as an example of a display unit to which the eyepiece lens according to the present embodiment is applied. The head-mounted display200includes a main body section201, a forehead support section202, a nose support section203, a head band204, and a headphone205. The forehead support section202is provided at an upper-middle part of the main body section201. The nose support section203is provided at a lower-middle part of the main body section201.

When the user wears the head-mounted display200at one's head, the forehead support section202becomes in contact with forehead of the user, and the nose support section203becomes in contact with nose of the user. Further, the head band204becomes in contact with the back of the head of the user. Thus, the weight of the unit is dispersed to the entire head in this head-mounted display200. Thus, it is possible to wear this head-mounted display200with reducing the load on the user.

The headphone205for left and right ears is provided. This allows audio sound to be provided independently to one's left ear and to one's right ear.

The main body section201includes a circuit substrate, an optical system, etc. for displaying an image. The main body section201includes a left-eye display section210L and a right-eye display section210R as shown inFIG. 42. This allows an image to be provided independently to one's left eye and to one's right eye. The left-eye display section210L includes the image display device100for left eye and an eyepiece optical system for left eye that magnifies the image displayed on the image display device100for left eye. The right-eye display section210R includes the image display device100for right eye and an eyepiece optical system for right eye that magnifies the image displayed on the image display device100for right eye. The eyepiece lens according to the present embodiment is applicable as the above-described respective eyepiece optical systems for left and right eyes.

It is to be noted that image data is supplied from an image reproducing unit which is not illustrated to the image display device100. It is also possible to perform three-dimensional display by supplying three-dimensional image data from the image reproducing unit and displaying images that have parallaxes on the left-eye display section210L and the right-eye display section210R.

It is to be noted that, although an example in which the display unit is applied to the head-mounted display200has been described above, the range of application of the display unit according to the present embodiment is not limited to the head-mounted display200. The display unit according to the present embodiment is applicable to a unit such as an electronic binocular and an electronic view finder in a camera.

Also, the eyepiece lens according to the present embodiment is not limitedly used in order to magnify the image displayed on the image display device100, and is applicable also to an observation unit such as those magnifying an optical image formed by an objective lens.

EXAMPLES

4. Numerical Examples of Lenses

Next, description will be given of specific numerical examples of the eyepiece lens according to the present embodiment.

Symbols etc. in tables and the description below represent the following. “Si” represents the number of an i-th surface where 1 is attached to the eye point E.P. and the number becomes larger in order as the relevant surface is closer to the image side. “Ri” represents a curvature radius (mm) of the i-th surface. “Di” represents a spacing (mm) on the optical axis between the i-th surface and the (i+1)th surface. “Ndi” represents a value of a refractive index of the d-line (having a wavelength of 587.6 nm) of a material (a medium) of an optical component that has the i-th surface. “vdi” represents a value of an Abbe number, with respect to the d-line, of the material of the optical component that has the i-th surface. A surface having a curvature radius of “∞” is a planar surface or an aperture surface (an aperture stop STO).

A shape of an aspherical surface is represented by the following expression. In the later-described respective tables that show aspherical surface coefficients, for example, “E-i” represents an exponential expression having 10 as a base, i.e., “10−i”. To give an example, “0.12345E-05” represents “0.12345×10−5”.

In the above-described expression, Z is a depth of the aspherical surface, Y is a height from the optical axis, R is a paraxial curvature radius, K is a conic constant, and Ai is an aspherical surface coefficient of i-th order (i is an integer of 3 or larger).

Configuration Common to Respective Numerical Examples

Any of eyepiece lenses according to the respective numerical examples below has a configuration that satisfies the above-described basic configuration of the lens. Also, the respective lens surfaces of the first lens L1and the second lens L2are aspherical.

Numerical Example 1

Tables 1 and 2 show specific lens data corresponding to an eyepiece lens1according to a first configuration example shown inFIG. 1. In particular, Table 1 shows basic lens data thereof, and Table 2 shows data related to aspherical surfaces.FIG. 2shows spherical aberration, astigmatism, and distortion as various aberrations of the eyepiece lens1according to this Numerical example 1. Each aberration is obtained by tracing a light ray from the eye point E.P. side. In each aberration diagram, a solid line shows aberration at a wavelength of 545 nm, a dashed-dotted line shows aberration of at a wavelength of 460 nm, and a dashed line shows aberration at a wavelength of 620 nm. In the astigmatism diagram, X represents aberration in a sagittal direction and Y represents aberration in a meridional direction. The same is applicable to aberration diagrams in Numerical examples 2 to 20 which will be described later.

Numerical Example 2

Tables 3 and 4 show specific lens data corresponding to an eyepiece lens2according to a second configuration example shown inFIG. 3. In particular, Table 3 shows basic lens data thereof, and Table 4 shows data related to aspherical surfaces.FIG. 4shows various aberrations of the eyepiece lens2according to this Numerical example 2.

Numerical Example 3

Tables 5 and 6 show specific lens data corresponding to an eyepiece lens3according to a third configuration example shown inFIG. 5. In particular, Table 5 shows basic lens data thereof, and Table 6 shows data related to aspherical surfaces.FIG. 6shows various aberrations of the eyepiece lens3according to this Numerical example 3.

Numerical Example 4

Tables 7 and 8 show specific lens data corresponding to an eyepiece lens4according to a fourth configuration example shown inFIG. 7. In particular, Table 7 shows basic lens data thereof, and Table 8 shows data related to aspherical surfaces.FIG. 8shows various aberrations of the eyepiece lens4according to this Numerical example 4.

Numerical Example 5

Tables 9 and 10 show specific lens data corresponding to an eyepiece lens5according to a fifth configuration example shown inFIG. 9. In particular, Table 9 shows basic lens data thereof, and Table 10 shows data related to aspherical surfaces.FIG. 10shows various aberrations of the eyepiece lens5according to this Numerical example 5.

Numerical Example 6

Tables 11 and 12 show specific lens data corresponding to an eyepiece lens 6 according to a sixth configuration example shown inFIG. 11. In particular, Table 11 shows basic lens data thereof, and Table 12 shows data related to aspherical surfaces.FIG. 12shows various aberrations of the eyepiece lens6according to this Numerical example 6.

Numerical Example 7

Tables 13 and 14 show specific lens data corresponding to an eyepiece lens7according to a seventh configuration example shown inFIG. 13. In particular, Table 13 shows basic lens data thereof, and Table 14 shows data related to aspherical surfaces.FIG. 14shows various aberrations of the eyepiece lens7according to this Numerical example 7.

Numerical Example 8

Tables 15 and 16 show specific lens data corresponding to an eyepiece lens8according to an eighth configuration example shown inFIG. 15. In particular, Table 15 shows basic lens data thereof, and Table 16 shows data related to aspherical surfaces.FIG. 16shows various aberrations of the eyepiece lens8according to this Numerical example 8.

Numerical Example 9

Tables 17 and 18 show specific lens data corresponding to an eyepiece lens9according to a ninth configuration example shown inFIG. 17. In particular, Table 17 shows basic lens data thereof, and Table 18 shows data related to aspherical surfaces.FIG. 18shows various aberrations of the eyepiece lens9according to this Numerical example 9.

Numerical Example 10

Tables 19 and 20 show specific lens data corresponding to an eyepiece lens10according to a tenth configuration example shown inFIG. 19. In particular, Table 19 shows basic lens data thereof, and Table 20 shows data related to aspherical surfaces.FIG. 20shows various aberrations of the eyepiece lens10according to this Numerical example 10.

Numerical Example 11

Tables 21 and 22 show specific lens data corresponding to an eyepiece lens11according to an eleventh configuration example shown inFIG. 21. In particular, Table 21 shows basic lens data thereof, and Table 22 shows data related to aspherical surfaces.FIG. 22shows various aberrations of the eyepiece lens11according to this Numerical example 11.

Numerical Example 12

Tables 23 and 24 show specific lens data corresponding to an eyepiece lens12according to a twelfth configuration example shown inFIG. 23. In particular, Table 23 shows basic lens data thereof, and Table 24 shows data related to aspherical surfaces.FIG. 24shows various aberrations of the eyepiece lens12according to this Numerical example 12.

Numerical Example 13

Tables 25 and 26 show specific lens data corresponding to an eyepiece lens13according to a thirteenth configuration example shown inFIG. 25. In particular, Table 25 shows basic lens data thereof, and Table 26 shows data related to aspherical surfaces.FIG. 26shows various aberrations of the eyepiece lens13according to this Numerical example 13.

Numerical Example 14

Tables 27 and 28 show specific lens data corresponding to an eyepiece lens14according to a fourteenth configuration example shown inFIG. 27. In particular, Table 27 shows basic lens data thereof, and Table 28 shows data related to aspherical surfaces.FIG. 28shows various aberrations of the eyepiece lens14according to this Numerical example 14.

Numerical Example 15

Tables 29 and 30 show specific lens data corresponding to an eyepiece lens15according to a fifteenth configuration example shown inFIG. 29. In particular, Table 29 shows basic lens data thereof, and Table 30 shows data related to aspherical surfaces.FIG. 30shows various aberrations of the eyepiece lens15according to this Numerical example 15.

Numerical Example 16

Tables 31 and 32 show specific lens data corresponding to an eyepiece lens16according to a sixteenth configuration example shown inFIG. 31. In particular, Table 31 shows basic lens data thereof, and Table 32 shows data related to aspherical surfaces.FIG. 32shows various aberrations of the eyepiece lens16according to this Numerical example 16.

Numerical Example 17

Tables 33 and 34 show specific lens data corresponding to an eyepiece lens17according to a seventeenth configuration example shown inFIG. 33. In particular, Table 33 shows basic lens data thereof, and Table 34 shows data related to aspherical surfaces.FIG. 34shows various aberrations of the eyepiece lens17according to this Numerical example 17.

Numerical Example 18

Tables 35 and 36 show specific lens data corresponding to an eyepiece lens18according to an eighteenth configuration example shown inFIG. 35. In particular, Table 35 shows basic lens data thereof, and Table 36 shows data related to aspherical surfaces.FIG. 36shows various aberrations of the eyepiece lens18according to this Numerical example 18.

Numerical Example 19

Tables 37 and 38 show specific lens data corresponding to an eyepiece lens19according to a nineteenth configuration example shown inFIG. 37. In particular, Table 37 shows basic lens data thereof, and Table 38 shows data related to aspherical surfaces.FIG. 38shows various aberrations of the eyepiece lens19according to this Numerical example 19.

Numerical Example 20

Tables 39 and 40 show specific lens data corresponding to an eyepiece lens20according to a twentieth configuration example shown inFIG. 39. In particular, Table 39 shows basic lens data thereof, and Table 40 shows data related to aspherical surfaces.FIG. 40shows various aberrations of the eyepiece lens20according to this Numerical example 20.

Other Numerical Data of Respective Examples

Table 41 summarizes values related to the above-described respective conditional expressions for the respective numerical examples. Tables 42 and 43 each summarize values of parameters used in the above-described respective conditional expressions for the respective numerical examples. As can be seen from Table 41, each of the values in the respective numerical examples falls within a range of the related numerical values in each conditional expression.

5. Other Embodiments

The technology of the present disclosure is not limited to the above description of the embodiment and Examples, and various modifications may be made.

For example, the shapes and the numerical values shown in the above-described respective numerical examples are mere examples for embodying the present technology, and should not be used to limitedly understand the technical range of the present technology.

In the above-described embodiment and Examples, the configuration substantially configured of two lenses has been described. However, a lens substantially having no refractive power may be further included.

It is possible to achieve at least the following configurations from the above-described example embodiments and the modifications of the disclosure.

a first lens having positive refractive power, the first lens having a convex surface that faces toward an eye point side; and

a second lens having positive refractive power, the second lens having a convex surface that faces toward the eye point side,

the first and second lenses being arranged in order from the eye point side, wherein

where h is a height of the image at a horizontal end,

ω is a half angle of view in a horizontal direction,

E is a distance from an eye point to the first lens, the distance being an eye relief, and

L is a distance from the eye point to the image.

[2] The eyepiece lens according to [1], wherein a following conditional expression is satisfied,
3.7>(f1×f2)1/2/f>1.4  (3)

where f is a total focal length,

f1 is a focal length of the first lens, and

f2 is a focal length of the second lens.

[3] The eyepiece lens according to [1] or [2], wherein a following conditional expression is satisfied,
40>|(R3+R5)/(R3−R5)|  (4)

where R3 is a paraxial curvature radius of an image-sided surface of the first lens, and

R5 is a paraxial curvature radius of an image-sided surface of the second lens.

[4] The eyepiece lens according to any one of [1] to [3], wherein a following conditional expression is satisfied,
1.9>R4/f2>0.4  (5)

where R4 is a paraxial curvature radius of the eye-point-sided surface of the second lens.

[5] The eyepiece lens according to any one of [1] to [4], wherein a following conditional expression is satisfied,
1.0>R2/f1>0.1  (6)

where R2 is a paraxial curvature radius of the eye-point-sided surface of the first lens.

[6] The eyepiece lens according to any one of [1] to [5], wherein a following conditional expression is satisfied, wherein
1.2>(D2+D4)/(D3+D5)>0.2  (7)

wherein D2 is a central thickness of the first lens,

D3 is a spacing between the first lens and the second lens,

D4 is a central thickness of the second lens, and

D5 is a spacing between the second lens and the image.

[7] The eyepiece lens according to any one of [1] to [6], wherein an image-sided surface of the first lens and an image-sided surface of the second lens each have an aspherical shape.

[8] The eyepiece lens according to any one of [1] to [7], wherein the eye-point-sided surface of the first lens has an aspherical shape that has an inflection point.

[9] The eyepiece lens according to any one of [1] to [8], wherein the first and second lenses are each configured of a material having a linear expansion coefficient of 20×10−6/° C. or larger.

[10] The eyepiece lens according to any one of [1] to [9], further including a lens substantially having no refractive power.

[11] A display unit including:

an image display device; and

an eyepiece lens configured to allow an image displayed on the image display device to be magnified,

the eyepiece lens including

a first lens having positive refractive power, the first lens having a convex surface that faces toward an eye point side, and

a second lens having positive refractive power, the second lens having a convex surface that faces toward the eye point side,

the first and second lenses being arranged in order from the eye point side, wherein

where h is a height of the image at a horizontal end,

ω is a half angle of view in a horizontal direction,

E is a distance from an eye point to the first lens, the distance being an eye relief, and

L is a distance from the eye point to the image.

[12] The display unit according to [11], wherein the eyepiece lens further includes a lens substantially having no refractive power.