JP2005084522A - Combiner optical system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combiner optical system with thickness-reducible constitution. <P>SOLUTION: The combiner optical system is equipped with a transparent substrate (15) in which the optical path of display luminous flux introduced from an image display surface (20a) is formed, a beam splitter (13) which is inserted into the optical path formed in the substrate and transmits at least a portion of the display luminous flux, and a main reflecting surface (17) which imparts optical power to the display luminous flux transmitted through the beam splitter and reflects the display luminous flux in a direction where the display luminous flux is made incident again on the beam splitter. The angle of the beam splitter to the top surface of the substrate is set to 20 to 40°. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a combiner optical system that is mounted on a portable device such as an eyeglass display and presents it to a user's eye by superimposing a display light beam emitted from an image display surface in the portable device on external light.

A combiner optical system may be used for viewers of eyeglass displays, wearable personal computers, cameras, and other portable devices (such as the combiner optical system of Patent Document 1).
The combiner optical system transmits external light incident from the outside and forms a virtual image of the image display surface in the portable device in front of the user's eyes.

In order to stabilize the position of the virtual image, the combiner optical system is fixed with respect to the user's head (see FIG. 3B of Patent Document 1).
Further, in order to facilitate the fixing, a device for reducing the weight is applied to the material and arrangement relationship of the optical members constituting the combiner optical system.
In addition, the combiner optical system disclosed in Patent Document 1 has a beam splitter (FIG. 8, reference numeral 360 in FIG. 8), a main reflection surface (FIG. 8, reference numeral 550 in Patent Document 1), and the like arranged close to the user's eye. It is also compact.
US Pat. No. 6,222,677

However, in order to stabilize the posture (attachment position and angle) of the combiner optical system, it is necessary not only to reduce the weight, but also to make the shape suitable for mounting on the user's eyes.
For this reason, it is desirable to make the main part of the combiner optical system the same size as the size of the eye, and to make it thin in the direction of the user's visual axis (that is, close to the shape of a so-called spectacle lens). In fact, it is considered that the posture is more stable when thinned even at the expense of compactness.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a combiner optical system that can be thinned.

  The combiner optical system according to claim 1, wherein a transparent substrate that internally forms an optical path of a display light beam introduced from an image display surface, a beam splitter inserted in the optical path formed in the substrate, An optical power is applied to the display light beam that has passed through the beam splitter, and a main reflection surface that reflects the display light beam in a direction in which the display light beam reenters the beam splitter, and the beam splitter includes the substrate The angle formed with the surface is 20 ° or more and 40 ° or less.

The combiner optical system according to claim 2 is the combiner optical system according to claim 1, wherein the main reflection surface is perpendicular to a principal ray of the display light beam emitted from a center of the image display surface. Features.
The combiner optical system according to a third aspect is the combiner optical system according to the first or second aspect, wherein the beam splitter is a polarization beam splitter, and the beam splitter is disposed between the beam splitter and the main reflecting surface. A quarter wavelength plate is inserted in the optical path of the display light beam.

The combiner optical system according to claim 4 is the combiner optical system according to claim 3, wherein the polarization beam splitter has a reflection wavelength selectivity with a wavelength of the display light beam as a selected wavelength. And
A combiner optical system according to a fifth aspect is the combiner optical system according to the fourth aspect, wherein the polarization beam splitter is formed of a reflection hologram.

Thus, if the angle formed by the beam splitter and the surface of the substrate is suppressed to 40 ° or less, the substrate can be thinned. Further, if the angle is ensured to be 20 ° or more, a polygonal optical path can be appropriately formed inside the substrate.
That is, according to the present invention, a combiner optical system having a thinnable configuration is realized.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1, 2, and 3.
In the present embodiment, a combiner optical system 1 mounted on an eyeglass display will be described.
First, the configuration of the combiner optical system 1 will be described.
The appearance of the eyeglass display is as shown in FIG. In FIG. 1, reference numeral 1 denotes a combiner optical system. The outline of the cross section of the combiner optical system 1 is as shown in FIG.

As shown in FIGS. 1 and 2, the combiner optical system 1 guides the display light beam emitted from the image display surface 20a of the light source unit 3 in the eyeglass display toward the pupil of the user's eye. In addition, what is shown with the code | symbol 16 in FIG. 1 is a mounting tool for mounting | wearing a user's head with an eyeglass display.
The position of the origin of the right-handed XYZ coordinates shown in FIGS. 1 and 2 is the position of the center of the user's pupil. This pupil is also the exit pupil (eye point EP) of the combiner optical system 1. 1 and 2, the Z axis of the XYZ coordinate system is the visual axis direction of the user's eyes, the Y axis is the left and right direction of the user, and the X axis is the vertical direction of the user.

The combiner optical system 1 includes a parallel substrate 15. Further, the substrate 15 includes a main reflection surface 17, a polarization beam splitter (PBS) 13, a quarter wavelength plate 14, and the like.
The outer edge of the substrate 15 is adjusted to a size and shape like a spectacle lens, and is arranged to face the user's eyes.
The image display surface 20a is disposed at a position sufficiently away from the user's eyes. The wavelength of the display light beam emitted from the image display surface 20a is set to a predetermined wavelength of visible light, and the polarization direction of the display light beam is adjusted to p-polarized light in advance.

The material of the substrate 15 is made of a material that is at least transparent to visible light having a predetermined wavelength. It is desirable to use an optical resin for weight reduction.
The angle range of the display light beam that diverges from each position on the image display surface 20a is appropriately limited. This can be realized, for example, by using illumination light that illuminates the image display surface 20a that has been sufficiently collimated (parallel light flux) in advance.

The PBS 13 is provided in a posture inclined in front of the user's eyes. The angle θ formed by the PBS 13 with the user-side surface 15a or the external-side surface 15b of the substrate 15 is not less than 20 ° and not more than 40 °.
The PBS 13 has a reflection wavelength selectivity that reflects the predetermined wavelength as a selected wavelength and does not reflect visible light of other wavelengths.

The arrangement position and the arrangement angle of the image display surface 20a are such that the display light beam emitted from the image display surface 20a is internally reflected alternately by the user-side surface 15a and the external-side surface 15b of the substrate 15 to form a broken line optical path. The angle formed between the substrate 15 and the optical path and the PBS 13 is selected to be an appropriate value.
The region (boundary surface) 15c where the display light beam emitted from the image display surface 20a first enters on the substrate 15 is from the center of the image display surface 20a in order to avoid the presence of an asymmetric element with respect to the image formation of the light beam. The plane is substantially perpendicular to the principal ray of the emitted display light beam.

The main reflection surface 17 is provided at a position where the display light beam transmitted through the PBS 13 can be reflected.
The main reflection surface 17 has a curvature or a diffraction pattern for applying optical power to the display light beam.
The posture of the main reflection surface 17 is set such that the principal ray of the display light beam emitted from the center of the image display surface 20 a is incident on the main reflection surface 17 perpendicularly.

The quarter-wave plate 14 is inserted in the optical path of the display light beam between the PBS 13 and the main reflection surface 17 (as close as possible to the main reflection surface 17).
Next, the behavior of light in the combiner optical system 1 will be described.
The p-polarized display light beam emitted from the image display surface 20a is internally reflected inside the substrate 15 and then enters the PBS 13, passes through the PBS 13, passes through the quarter-wave plate 14, and enters the main reflecting surface 17. . The display light beam passes through the quarter-wave plate 14 again and is incident again on the PBS 13 while being brought close to a parallel light beam by reflection on the main reflection surface 17.

Since the display light beam reciprocating the quarter-wave plate 14 becomes s-polarized light, the display light beam re-entering the PBS 13 is reflected by the PBS 13. Since the angle formed by the optical path of the display light beam with the PBS 13 is an appropriate value, the display light beam reflected by the PBS 13 travels in the direction of the user's eye and enters the eye pupil in a state close to a parallel light beam.
Therefore, an enlarged virtual image of the image display surface 20a is formed on the external side of the PBS 13. In this state, it appears to the user that the image display surface 20a is in front of the eyes. In addition, since the PBS 13 transmits most of the external light incident from the outside, the observer can also see the outside with a virtual image.

Next, the effect of this combiner optical system 1 will be described.
First, the optical elements arranged on the visual axis (Z-axis) of the user's eye are only the substrate 15 and the PBS in the substrate 15, and are fewer than the conventional example.
Moreover, the angle θ between the PBS 13 and the user-side surface 15a or the external-side surface 15b of the substrate 15 is 40 ° or less, which is 5 ° smaller than that of the conventional example (45 °). If it is smaller by 5 °, the distance between the user-side surface 15a and the external-side surface 15b of the substrate 15 is reliably reduced.

Therefore, the thickness of the combiner optical system 1 in the visual axis direction (Z direction) is thinner than that of the conventional example.
In addition, since the angle θ formed by the PBS 13 and the user-side surface 15a or the external-side surface 15b of the substrate 15 is 20 ° or more, a polygonal optical path is appropriately formed inside the substrate 15. That is, in the user-side surface 15a or the external-side surface 15b of the substrate 15, the region that reflects the display light beam n-th time and the region that reflects the n + 1-th time can be made independent (not overlapped).

Incidentally, when the angle θ formed by the PBS 13 and the user-side surface 15a or the external-side surface 15b of the substrate 15 is less than 20 °, it is difficult to properly form the optical path.
In addition, since the angular range of the light beam that diverges from each position on the image display surface 20a is appropriately limited, it is possible to suppress the stray light and avoid the occurrence of a ghost due to the stray light near the virtual image.

Further, the posture of the main reflection surface 17 is set such that the principal ray of the display light beam emitted from the center of the image display surface 20a is perpendicularly incident on the main reflection surface 17, so that the virtual image is formed. Aberrations are minimized.
Further, the PBS 13 has a reflection wavelength selectivity and transmits all light having a wavelength different from that of the display light beam. Therefore, the see-through property (external light transmission property) of the combiner optical system 1 is high.
(Other)
It should be noted that illumination light is used to limit the angle range of the light beam that diverges from each position on the image display surface 20a, but a field lens may be inserted on the exit side of the image display surface 20a instead.

In addition, a transmissive or reflective two-dimensional image display element such as an LCD or a self-luminous two-dimensional image display element such as an EL is disposed on the image display surface 20a.
Further, instead of arranging the two-dimensional image display element directly on the image display surface 20a, an intermediate image formed by projecting the two-dimensional image display element by the relay optical system may be arranged. Further, a two-dimensional image by optical scanning may be formed on the image display surface 20a.

Further, the shape of the image display surface 20a is not limited to a flat surface, and may be a spherical surface convex toward the substrate 15 side.
The boundary surface 15c of the substrate 15 is not limited to a flat surface, and may be a concave or convex curved surface. It is desirable to optimize the shape so that various aberrations can be easily suppressed.
Further, an additional lens may be inserted between the image display surface 20 a and the substrate 15. By inserting an additional lens, it becomes easy to control curvature of field and correct chromatic aberration. The additional lens may be bonded to the substrate 15 or separated from the substrate 15.

If the loss of light amount is allowed, a BS (beam splitter) may be provided instead of the PBS 13 and the quarter wavelength plate 14 may be omitted. At this time, it is not necessary to preliminarily adjust the display light flux to p-polarized light.
In addition, the PBS 13 having the reflection wavelength selectivity described above includes a polarization separation film made of a GBO (Giant Birefringent Optics) film, a polarization separation film made of a reflection hologram, a polarization separation film made of an optical multilayer film, and a polarization of a wire grid structure. It can be realized by a separation membrane.

Incidentally, in manufacturing a polarization separation film made of a hologram, in order to control the reflection wavelength band, multiple exposure in which the irradiation light wavelength or irradiation light angle is slightly shifted may be applied.
Further, when there is no need to increase the see-through property of the combiner optical system 1, it is not necessary to provide the reflective wavelength selectivity to the PBS 13. PBS 13 having no reflection wavelength selectivity can be easily realized by a polarization separation film made of aluminum or the like.

The main reflection surface 17 can be realized by a metal film, a dielectric film, a reflection hologram, or the like.
The positional relationship between the PBS 13 and the main reflection surface 17 may be as shown in FIG. 3 in addition to that shown in FIG.
The main reflection surface 17 of FIG. 2 reflects the display light beam that is reflected once by the user-side surface 15a of the substrate 15 after passing through the PBS 13, whereas the main reflection surface 17 of FIG. The displayed light beam is directly reflected.

  Further, the formation position of the main reflection surface 17 is not limited to the inside of the substrate 15 but may be the end surface of the substrate 15.

The first embodiment of the present invention will be described below.
The optical path diagram of the combiner optical system of the present embodiment is as shown in FIG. In FIG. 4, some surfaces that do not act on the optical path are omitted. Also, each element in FIG. 4 is assigned the same reference numeral as the corresponding element in the embodiment (the same applies to FIGS. 6, 8, 10, and 12).

  The data of this combiner optical system is as shown in Tables 1 and 2.

なお、表１，表２に示すデータの光線追跡の方向は、射出瞳（アイポイントＥ．Ｐ．）から画像表示面２０ａへ向かう方向とした。また、座標系は、射出瞳の中心に原点を有した右手系のＸＹＺ座標を採用した。ＸＹＺ座標系のＺ軸は使用者の眼の視軸方向、Ｙ軸は使用者の左右方向、Ｘ軸は使用者の上下方向である。また、表１，表２中の数値の単位は、個別の指定のあるものを除き、長さは［ｍｍ］である。また、表１において、屈折率，分散はｄ線に対する値である。また、表２において「Ｘ」はＸ座標値、「Ｙ」はＹ座標値、「Ｚ」はＺ座標値、「Ａ」はＸ軸からの傾き角度、「Ｂ」はＹ軸からの傾き角度、「Ｃ」はＺ軸からの傾き角度を示す（以上、他の各表においても同様）。

The direction of ray tracing of the data shown in Tables 1 and 2 was a direction from the exit pupil (eye point EP) toward the image display surface 20a. As the coordinate system, a right-handed XYZ coordinate having an origin at the center of the exit pupil was adopted. The Z axis of the XYZ coordinate system is the visual axis direction of the user's eyes, the Y axis is the left and right direction of the user, and the X axis is the vertical direction of the user. In addition, the unit of numerical values in Tables 1 and 2 is [mm] except for those individually specified. In Table 1, the refractive index and dispersion are values for the d-line. In Table 2, “X” is an X coordinate value, “Y” is a Y coordinate value, “Z” is a Z coordinate value, “A” is an inclination angle from the X axis, and “B” is an inclination angle from the Y axis. , “C” indicates an inclination angle from the Z axis (the same applies to the other tables).

The aberration diagram of this combiner optical system is as shown in FIG.
The aberration diagram shown in FIG. 5 is a lateral aberration diagram. In FIG. 5, “Y-FAN” is a lateral aberration diagram in the Y direction, and “X-FAN” is a lateral aberration diagram in the X direction. The central coordinates (X °, Y °) are the angles of view (the same applies to FIGS. 7, 9, and 11).

The second embodiment of the present invention will be described below.
The optical path diagram of the combiner optical system of the present embodiment is as shown in FIG. In FIG. 6, some surfaces that do not act on the optical path are omitted.
The data of this combiner optical system is as shown in Tables 3 and 4.

なお、１１面（非球面）の定義式は、式（１）のとおりである。

In addition, the definition formula of 11 surfaces (aspherical surface) is as Formula (1).

このコンバイナ光学系の収差図は、図７のとおりである。

The aberration diagram of this combiner optical system is as shown in FIG.

The third embodiment of the present invention will be described below.
The optical path diagram of the combiner optical system of this example is as shown in FIG. In FIG. 8, some surfaces that do not act on the optical path are omitted.
The data of this combiner optical system are as shown in Tables 5 and 6.

このコンバイナ光学系の収差図は、図９のとおりである。

The aberration diagram of this combiner optical system is as shown in FIG.

The fourth embodiment of the present invention will be described below.
The optical path diagram of the combiner optical system of this example is as shown in FIG. In FIG. 10, some surfaces that do not act on the optical path are omitted.
The data of this combiner optical system are as shown in Tables 7 and 8.

このコンバイナ光学系の収差図は、図１１のとおりである。

The aberration diagram of this combiner optical system is as shown in FIG.

The fifth embodiment of the present invention will be described below.
The optical path diagram of the combiner optical system of the present embodiment is as shown in FIG. In FIG. 12, some surfaces that do not act on the optical path are omitted.
The data of this combiner optical system are as shown in Table 9 and Table 10.

It is an external view of an eyeglass display. It is the schematic of the cross section of the combiner optical system 1 of embodiment. It is the schematic of the cross section of another combiner optical system 1 of embodiment. It is an optical path figure of the combiner optical system of 1st Example. FIG. 6 is an aberration diagram (lateral aberration diagram) of the combiner optical system of the first example. It is an optical path figure of the combiner optical system of 2nd Example. It is an aberration diagram (lateral aberration diagram) of the combiner optical system of the second example. It is an optical path figure of the combiner optical system of 3rd Example. It is an aberration diagram (lateral aberration diagram) of the combiner optical system of the third example. It is an optical path figure of the combiner optical system of 4th Example. It is an aberration diagram (lateral aberration diagram) of the combiner optical system of the fourth example. It is an optical path figure of the combiner optical system of 5th Example.

Explanation of symbols

1 Combiner optical system 20a Image display surface 13 Beam splitter (BS), polarization beam splitter (PBS)
14 1/4 wavelength plate 15 Substrate 15a User side surface 15b External field side surface 15c Boundary surface 17 Main reflection surface P. Exit pupil (eye point)

Claims (5)

A transparent substrate that internally forms an optical path of a display light beam introduced from the image display surface;
A beam splitter inserted into the optical path formed in the substrate;
The optical power is applied to the display light beam transmitted through the beam splitter, and a main reflection surface that reflects the display light beam in a direction in which the display light beam re-enters the beam splitter,
An angle formed by the beam splitter and the surface of the substrate is 20 ° or more and 40 ° or less. The combiner optical system according to claim 1,
The combiner optical system, wherein the main reflection surface is perpendicular to a principal ray of the display light beam emitted from the center of the image display surface. The combiner optical system according to claim 1 or 2,
The beam splitter is a polarizing beam splitter;
A combiner optical system, wherein a quarter-wave plate is inserted in an optical path of the display light beam between the beam splitter and the main reflection surface. The combiner optical system according to claim 3,
The combiner optical system, wherein the polarization beam splitter has a reflection wavelength selectivity with a wavelength of the display light beam as a selection wavelength. The combiner optical system according to claim 4,
The combiner optical system, wherein the polarization beam splitter is made of a reflection hologram.

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