JP4609160B2 - Optical element, combiner optical system, and information display device - Google Patents

Description

  The present invention relates to an optical element for see-through light propagation, a combiner optical system using the optical element, and an information display device using the combiner optical system.

High refractive index materials (transparent substrates) such as glass substrates that exist in low refractive index media such as air, vacuum, and other gases internally reflect the light beam incident on the transparent substrate at an angle larger than the critical angle. However, the incident light beam is transmitted at an angle smaller than the critical angle. That is, it has an internal reflection function and see-through property.
One of information display devices using this transparent substrate as an optical element for light propagation is an eyeglass display (Patent Document 1, Patent Document 2, etc.).

The eyeglass display has a transparent substrate placed in front of the observer's eyes, and the display light flux from the image display element propagates through the transparent substrate to just before the pupil of the observation eye, and is further provided in the transparent substrate. It is incident on the pupil superimposed on the external light flux on a combiner such as a half mirror.
With such an eyeglass display, an observer can observe the outside world and the image of the image display element at the same time.

In order to widely disseminate this eyeglass display, it is necessary to add a function (diopter correction function) similar to that of glasses together with various other functions.
JP 2001-264682 A Special table 2003-536102 gazette

However, an eyeglass display that uses the inner surface reflection function of a transparent substrate can have a transparent substrate surface with a curved surface to give the transparent substrate itself a refractive power, or another refractive member having a refractive power (a plano-convex lens or a flat plate). It is basically impossible to attach a concave lens to the surface of a transparent substrate.
For this reason, it is currently considered as a method for adding a diopter correction function to attach such a refracting member to the surface of the transparent substrate through an air gap. There is.

For example, it is difficult to obtain mechanical strength while maintaining the air gap interval with the required accuracy, and the number of parts, weight, thickness, and the like are increased, and the manufacturing process is complicated and expensive. Further, depending on the positional relationship between the observation eye and the transparent substrate, extra reflected light due to the air gap may enter the observation eye, and visibility may be impaired.
The present invention has been made in view of these problems, and even if a member having a refractive index higher than that of the surrounding medium, such as a refractive member, is in close contact with the surface, the internal reflection function and the see-through property are not impaired. An object of the present invention is to provide an optical element.

  An object of the present invention is to provide a combiner optical system that facilitates diopter correction and an information display device that facilitates diopter correction.

The optical element of the present invention is provided in close contact with a substrate on which a predetermined light beam can propagate and a surface of the substrate on which the propagating predetermined light beam can reach, and reflects the predetermined light beam. And an optical function unit having an interference function of transmitting an external light flux coming to the surface, wherein the optical function unit is formed of an optical multilayer film.

The optical multilayer film may be a dielectric optical multilayer film.
The dielectric optical multilayer film may be formed by laminating at least two types of layers having different refractive indexes .

The optical function unit may have a property of reflecting the predetermined light beam having a specific polarization direction and transmitting a light beam having another polarization direction.
Further, the optical function unit is determined by a refractive index between the substrate and air, and reaches the surface at a critical angle under a condition where a light beam inside the substrate is totally reflected or an incident angle larger than the critical angle. The light beam may be reflected with a desired reflection characteristic.

Also, combiner optical system of the present invention, the predetermined optical element of the present invention for propagating light flux emitted internally provided in the optical element, the light flux propagating inside of the optical element from the image display device And a combiner that reflects in the direction and transmits the external light flux.
Incidentally, combiner optical system of the present invention may comprise a refractive lens for diopter correction that is provided in close contact with the optical function section.

The information display element of the present invention includes an image display element and the combiner optical system of the present invention .

According to the present invention, an optical element for light propagation that does not impair the internal reflection function and see-through performance even when a member having a higher refractive index than the surrounding medium is in close contact with the surface is realized.
According to the present invention, a combiner optical system with easy diopter correction and an information display device with easy diopter correction are realized.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, FIG. 3, and FIG.
The present embodiment is an embodiment of an eyeglass display (corresponding to the information display device in the claims).
First, the configuration of the eyeglass display will be described.

As shown in FIG. 1, the present eyeglass display includes an image display optical system 1, an image introduction unit 2, a cable 3, and the like. The image display optical system 1 and the image introduction unit 2 are supported by a support member 4 similar to the frame of spectacles and are mounted on the observer's head (the support member 4 is from a temple 4a, a rim 4b, a bridge 4c, etc. Become.).
The image display optical system 1 has the same external shape as a spectacle lens and is supported from the periphery by a rim 4b.

The image introduction unit 2 is supported by the temple 4a. The image introduction unit 2 is supplied with video signals and power from the external device via the cable 3.
At the time of wearing, the image display optical system 1 is arranged in front of one eye of the observer (hereinafter referred to as “right eye” and “observation eye”). Hereinafter, the eyeglass display at the time of wearing will be described with reference to the positions of the observer and the observation eye.

Inside the image introduction unit 2, as shown in FIG. 2, a liquid crystal display element 21 (corresponding to the image display element in the claims) for displaying an image based on a video signal supplied via the cable 3, and a liquid crystal An objective lens 22 having a focal point is disposed in the vicinity of the display element 21.
The image introduction unit 2 emits the display light beam L1 (visible light) emitted from the objective lens 22 toward the right end portion of the surface of the image display optical system 1 on the viewer side.

The image display optical system 1 includes a substrate 13, a substrate 11, and a substrate 12 that are stacked in close contact with each other in order from the viewer's side.
Each of the substrate 13, the substrate 11, and the substrate 12 is made of a material (for example, optical glass) that is transparent to at least visible light.
Of these, the substrate 11 is a parallel plate that repeatedly reflects the display light beam L1 introduced from the image introduction unit 2 on the outside surface 11-1 and the observer side surface 11-2 (the substrate in claims). Corresponding to).

The substrate 12 arranged on the outside side of the substrate 11 serves to correct the diopter of the observation eye. The substrate 12 is a lens in which the observer-side surface 12-2 is a flat surface and the external-surface 12-1 is a curved surface.
The substrate 13 disposed on the observer side of the substrate 11 also serves to correct the diopter of the observation eye. The substrate 13 is a lens in which the external-side surface 13-1 is a flat surface and the observer-side surface 13-2 is a curved surface.

Note that the region of the surface 13-2 through which the display light beam L1 first passes is a flat surface that does not give any optical power to the display light beam L1.
In addition, an introduction mirror 11a for changing the angle of the display light beam L1 to an angle at which the inside of the substrate 11 can be internally reflected is formed in a region where the display light beam L1 first enters inside the substrate 11.

In addition, a half mirror 11b (corresponding to a combiner in claims) that reflects the internally reflected display light beam L1 in the direction of the pupil is provided in a region facing the pupil of the observation eye inside the substrate 11.
In place of the half mirror 11b, HOE (abbreviation of holographic optical element) having a property of deflecting light that matches a predetermined diffraction condition in a predetermined direction may be used. The combiner may be provided with optical power.

Here, between the substrate 12 and the substrate 11, a replacement film 12a is provided in close contact with both. Further, a replacement film 13a is provided between the substrate 13 and the substrate 11 in close contact with each other (the replacement films 12a and 13a correspond to the optical function section in the claims).
The replacement films 12a and 13a have a property of reflecting visible light incident at an incident angle near 60 ° and transmitting visible light incident at an incident angle near 0 °.

Next, details of the arrangement of each surface of the image display optical system 1 will be described based on the behavior of the display light beam L1.
As shown in FIG. 2, the display light beam L <b> 1 emitted from the display screen of the liquid crystal display element 21 in the image introduction unit 2 (shown only in the central view angle is shown) is near 0 ° via the lens 22. Since it is incident on the substrate 13 at an incident angle, it passes through the substitution film 13 a and enters the substrate 11.

The display light beam L1 incident on the substrate 11 is incident on the introduction mirror 11a at a predetermined incident angle and reflected. The reflected display light beam L1 is incident on the substitution film 13a at an incident angle θ of about 60 °, and is reflected by the substitution film 13a toward the substitution film 12a. Since the incident angle with respect to the substitution film 12a is also θ, the display light beam L1 is also reflected by the substitution film 12a.
Therefore, the display light beam L1 propagates in the left direction of the observer away from the image introduction unit 2 while being repeatedly and alternately reflected by the replacement films 13a and 12a.

Thereafter, the display light beam L1 is incident on the half mirror 11b and reflected in the direction of the pupil of the observation eye.
Since the reflected display light beam L1 is incident on the substitution film 13a at an incident angle near 0 °, it passes through the substitution film 13a and enters the pupil of the observation eye through the substrate 13.
On the other hand, the external light flux L2 from the outside (far) is incident on the substitution film 12a through the substrate 12 at an incident angle near 0 °, so that it passes through the substitution film 12a and passes through the substrate 11 to the substitution film 13a. Incident at an incident angle near 0 °. The external light beam L2 passes through the substitution film 13a and enters the pupil of the observation eye through the substrate 13.

Here, the shape of the surface 12-1 on the outside world side of the substrate 12 and the shape of the surface 13-2 on the viewer side of the substrate 13 are set so as to correct the diopter of the observation eye.
Incidentally, diopter correction for the outside of the observation eye is achieved by a combination of the shapes of the surface 12-1 and the surface 13-2 arranged in the optical path of the external light flux L2. Diopter correction for the image of the observation eye is achieved by the shape of the surface 13-2 arranged in the optical path of the display light beam L1. In order to correct the diopter for the image of the observation eye, the position of the lens 22 in the optical axis direction and the position of the liquid crystal display element 21 in the optical axis direction may be adjusted.

In the above eyeglass display, the element arranged in the optical path from the liquid crystal display element 21 to the pupil corresponds to the combiner optical system in the claims.
Next, the replacement films 12a and 13a will be described in detail.
(1) Internal Total Reflection of Substrate 11 Generally, total internal reflection of the substrate 11 placed in a medium occurs when a critical angle θ _c expressed by the following formula (1) is exceeded.

θ _c = arcsin [n _m / n _g ] (1)
However, _nm is the refractive index of the medium, and _ng is the refractive index of the substrate 11. According to equation (1), it can be seen that in order for θ _c to exist, n _m < _ng must be satisfied.
For this reason, if the substrates 12 and 13 are directly attached to the surface of the substrate 11, the refractive index of the medium becomes too high and θ _c does not exist, and the internal reflection function is impaired.

On the other hand, when the air gap is provided on the surface of the substrate 11, the refractive index of the medium (air) is as low as 1 (n _m = 1.0), and therefore the material of the substrate 11 is a general optical glass BK7 ( _ng = 1). .56), the critical angle θ _c is approximately 40 ° according to the equation (1), and an internal reflection function is obtained.
Incidentally, the incident angle characteristic of the reflectance of the substrate 11 when the air gap is used is as shown in FIG.
(2) Dielectric optical multilayer film The following relation is clarified in the theory of dielectric optical multilayer film.

Consider a film configuration (below) of a symmetrical film consisting of a dielectric optical multilayer film sandwiched between substrates made of optical glass. Here, the symmetric film refers to a film configuration in which various types of layers are laminated symmetrically. In addition, in order to represent the configuration, a group of layers as one unit is listed with parentheses (the same applies hereinafter).
Substrate / (0.125L0.25H0.125L) ^k / substrate, or
Substrate / (0.125H0.25L0.125H) ^k / substrate In each layer group, H is a high-refractive index layer, L is a low-refractive index layer, the letter k in the upper right of each layer group is the number of times each layer group is stacked, and before each layer The number attached is the optical film thickness (nd / λ) with respect to the center wavelength of the incident light of each layer (the same applies hereinafter).

It is known that a symmetric film can be treated as an equivalent single film (equivalent film) having a certain virtual refractive index, and the symmetric film and the equivalent refractive index (equivalent refractive index) of this film are The theory is described in detail in HA.Macleod's “Thin-Film optical Filters 3 ^rd Edition”, and so on, so the details are omitted.
In this film configuration, when the equivalent refractive index of the equivalent film with respect to the normal incident light is selected to be the same as the refractive index of the substrate 11, no interface reflection occurs at all with respect to the normal incident light, and the transmittance is 100%. For light with a large incident angle, interface reflection occurs and the reflectance increases. This is because, in general, the apparent refractive index N of the dielectric changes as follows in accordance with the traveling angle θ of light in the dielectric.

N = ncosθ (s-polarized light)
N = n / cosθ (p-polarized light)
Where n is the refractive index of the dielectric. Incidentally, the amount of increase in the reflectance accompanying the increase in the incident angle is particularly remarkable for s-polarized light.
(3) Configuration of Substitution Films 12a and 13a The substitution films 12a and 13a do not impair both the internal reflection function of the substrate 11 described in (1) and the see-through property (= external visibility) of the substrate 11. It needs to be a thing. That is, it is necessary to have reflectivity with respect to the display light beam L1 and to have transparency with respect to the external light beam L2.

Therefore, the replacement films 12a and 13a reflect light incident at a critical angle or an angle larger than the critical angle, which is determined by a difference in refractive index between the substrate 11 and air, with high reflectance (preferably total reflection). Designed to have
In this embodiment, the property of the substitution films 12a and 13a is set to “a property of reflecting visible light incident at an incident angle near 60 ° and transmitting visible light incident at an incident angle near 0 °”. . This property can be obtained by the dielectric optical multilayer film described in (2).

Therefore, in this embodiment, dielectric optical multilayer films are used for the replacement films 12a and 13a.
The design method of the replacement films 12a and 13a is as follows.
The configuration of the substitution films 12a and 13a (unit layer group configuration, number of laminations, film thickness of each layer, refractive index of each layer, material of each layer, etc.) is an incident angle of light (60 ° in this case) that should obtain a high reflectance. Optimized for The refractive index of the substrate 11 is also optimized at the same time. The basic structure of the replacement films 12a and 13a is the symmetrical film described in (2).

However, since it is very rare that the solution obtained even if the theory described in (2) is simply applied and the refractive index of the existing thin-film material coincide, Apply 1 part.
The first idea is to insert several layers (matching layers) on the substrate 11 side for the purpose of matching with the substrate 11.

The second contrivance is to perform fine adjustment of absorption of the refractive index dispersion of the material and spectral / angular characteristics of reflectance / transmittance during optimization.
A third idea is to break symmetry (allowing asymmetry) as necessary.
A fourth idea is to use film thickness optimization design or automatic film composition synthesis by a computer.

A fifth idea is to design so that desired characteristics can be obtained only for s-polarized light (a dielectric optical multilayer film in which the amount of increase in reflectivity with increase in incident angle is significant with respect to s-polarized light). Because there is a nature.)
The sixth idea is to design such that a desired characteristic is obtained only for a specific wavelength.

The fifth device is effective when the light source of the liquid crystal display element 21 shown in FIG. 2 is s-polarized light. Further, even when the light source is p-polarized light, it is effective if the polarization direction is rotated by a phase plate or the like. There is an advantage that the degree of freedom of design is increased by limiting the polarization direction.
The sixth device is effective when the light source of the liquid crystal display element 21 shown in FIG. 2 emits light at a specific wavelength. There is an advantage that the degree of freedom of design is increased by limiting the wavelength.

Next, the effect of the present eyeglass display will be described.
In the eyeglass display, substitution films 12a and 13a are formed on the outside of the substrate 11 and the viewer side.
The properties of the replacement films 12a and 13a are set so as to reflect visible light incident at an incident angle of approximately 60 ° and transmit visible light incident at an incident angle of approximately 0 °.

The substrate 11 sandwiched between the replacement films 12a and 13a can reflect the display light beam L1 on the inner surface and transmit the external light beam L2 from the outside (far).
Therefore, although the substrates 12 and 13 having substantially the same refractive index as the substrate 11 are attached, the inner surface reflection function and see-through property of the substrate 11 are not impaired at all.
As a result, it was possible to mount the diopter correction function on the eyeglass display by a simple method of simply attaching the substrates 12 and 13.

If a material having light absorption is used as the substrates 12 and 13, the function of sunglasses can be imparted to the eyeglass display. Further, when only the function of sunglasses is necessary and diopter correction is not necessary, the substrates 12 and 13 may be parallel flat plates having light absorption.
(Other)
In the present embodiment, the display light beam L1 is set as visible light, and the properties of the substrate 11 and the replacement films 12a and 13a are set so as to reflect the visible light internally. However, the light source of the liquid crystal display element 21 emits light. When it has a spectrum, it should be set to a property that at least the light of the peak wavelength is internally reflected.

In the eyeglass display of this embodiment, diopter correction is achieved by two substrates (substrates 11 and 12) and two substitution films (substitution films 12a and 13a). Diopter correction may be achieved by a replacement film.
In this embodiment, the dielectric optical multilayer film is used as the replacement films 12a and 13a. However, HOE (corresponding to the diffractive optical surface in claims) may be used. The details of the configuration of the substitution films 12a and 13a using the dielectric optical multilayer film will be described in the examples described later, and the method for manufacturing the HOE will be described below.

FIG. 4 shows an optical system for manufacturing the HOE. This optical system manufactures an HOE that reflects the display light beam L1 incident at an incident angle θ with high reflectivity.
The laser light emitted from the laser light source 31 having the wavelength λ is divided into two by the beam splitter 32. The two divided laser beams are respectively enlarged by two beam expanders 33 and then incident on hologram photosensitive material 35 via two auxiliary prisms 34. As a result, the photosensitive material 35 is exposed. Here, the incident angle of the laser beam on the photosensitive material 35 is set to θ. If this photosensitive material 35 is developed, the HOE is completed.

The completed HOE has the property of diffracting and reflecting a light beam incident at a predetermined wavelength λ and a predetermined angle θ and totally transmitting light incident at an incident angle near 0 °.
Note that since the incident angle and wavelength of the light that the replacement films 12a and 13a should exhibit reflectivity are not one type, the photosensitive material 35 is subjected to multiple exposure while changing the angle θ and the wavelength of the laser light as necessary. become.

Further, when a resin-based material (resin sheet) is used as the hologram photosensitive material 35, a large area HOE can be manufactured at a low cost. Further, if the HOE is a resin sheet, it is only necessary to affix the HOE to the eyeglass display substrate 11 so that the practical value is high in terms of low cost and mass production.
In addition, an optical multilayer film made of a metal film, a semiconductor film, or the like may be used for the replacement films 12a and 13a of the present embodiment. However, the dielectric optical multilayer film is more preferable than the optical multilayer film because it absorbs less light.

Each of the above optical function sections (dielectric optical multilayer film, HOE, and other optical multilayer films) is preferably selected and used as the replacement films 12a and 13a according to the specifications and cost of the eyeglass display.
[First embodiment]
A first embodiment of the replacement films 12a and 13a made of a dielectric optical multilayer film will be described below.

This embodiment is an effective embodiment when the light source of the liquid crystal display element 21 is polarized. The basic configuration of this embodiment is, for example, as follows.
Substrate / (0.125L0.25H0.125L) ^k / substrate However, the refractive index of the substrate is 1.74, the refractive index of the high refractive index layer H is 2.20, and the refractive index of the low refractive index layer L is 1.48. is there. The substrate is composed of N-LAF35 manufactured by SCHOTT, the high refractive index layer H is made of any one of TiO ₂ , Ta ₂ O ₅ , and Nb ₂ O ₅ by adjusting the film forming conditions, and the low refractive index layer L is made of SiO _2. Consists of.

Incidentally, the dielectric optical multilayer film of this basic configuration is generally called a “short wavelength transmission filter”. There is a feature that the transmittance for light having a wavelength shorter than the predetermined wavelength is high and the reflectance for light having a wavelength longer than the predetermined wavelength is high.
In addition, a general dielectric optical multilayer film has a feature that the spectral characteristic when light is incident obliquely shifts to the short wavelength side according to the incident angle.

By combining these two characteristics and making the transmission band of vertically incident light coincide with the entire visible light (400 to 700 nm), and the incident angle is around the critical angle θ _c of the substrate 11, the reflection band on the long wavelength side is The basic configuration is optimized so as to overlap the entire visible light (400 to 700 nm). As a result of optimization, the present example was as follows.
Substrate / (0.125L0.28H0.15L) (0.125L0.25H0.125L) ⁴ (0.15L0.28H0.125L) / Substrate However, the refractive index of the substrate is 1.56 and the refractive index of the high refractive index layer H is 2. .30, the refractive index of the low refractive index layer L is 1.48, and the center wavelength λ is 850 nm. Substrate uses manufactured by SCHOTT N-BAK4, high refractive index layer H is configured by changing the film forming conditions from either _{TiO 2, Ta 2 O 5,} Nb 2 O 5.

FIG. 5 shows the angular characteristics of the reflectance of this embodiment, FIG. 6 shows the wavelength characteristics of the reflectance with respect to normal incident light, and FIG. 7 shows the wavelength characteristics of the reflectance with respect to 60 ° incident light. In the following figures, Rs is a characteristic for s-polarized light, Rp is a characteristic for p-polarized light, and Ra is an average characteristic for s-polarized light and p-polarized light.
As shown in FIG. 5, the angular characteristic of the reflectance of the present example is in good agreement with the angular characteristic of the reflectance of the glass substrate (see FIG. 3) when limited to s-polarized light. In addition, as shown in FIG. 6, the present example has a high transmittance for vertically incident visible light. Further, as shown in FIG. 7, the present example has a reflectance of approximately 100% with respect to visible light in a substantially entire area incident at 60 °.

In this embodiment, a matching layer is interposed between the substrate and the substrate. The matching layer plays the role of reducing ripples in the transmission band (wavelength region with low reflectance).
[Second Embodiment]
A second embodiment of the replacement films 12a and 13a made of a dielectric optical multilayer film will be described below.
This embodiment is an effective embodiment when the light source of the liquid crystal display element 21 is polarized. The basic configuration is as follows, for example.

Substrate / (0.125H0.25L0.125H) ^k / substrate By the way, this configuration is generally called “long wavelength transmission filter”. There is a feature that the transmittance for light having a wavelength longer than the predetermined wavelength is high and the reflectance for light having a wavelength shorter than the predetermined wavelength is high.
As a result of optimization, the present example was as follows.

Substrate / (0.3H0.27L0.14H) (0.1547H0.2684L0.1547H) ³ (0.14H0.27L0.3H) / Substrate However, the refractive index of the substrate is 1.56 and the refractive index of the high refractive index layer H is 2. .00, the refractive index of the low refractive index layer L is 1.48, and the center wavelength λ is 750 nm. The high refractive index layer H was configured by using any of ZrO ₂ , HfO ₅ , Sc ₂ O ₃ , Pr ₂ O ₆ , and Y ₂ O ₃ and adjusting the film forming conditions. The substrate and the low refractive index layer L were the same as those in the previous examples.

FIG. 8 shows the angular characteristics of the reflectance of this embodiment, FIG. 9 shows the wavelength characteristics of the reflectance with respect to the normal incident light, and FIG. 10 shows the wavelength characteristics of the reflectance with respect to the incident light of 60 °.
As shown in FIGS. 8, 9, and 10, according to this example, good characteristics similar to those of the first example can be obtained with respect to s-polarized light.
In this embodiment, a long wavelength transmission filter is used as a basic configuration. According to the theory described in (2) of the first embodiment, a short wavelength transmission filter is suitable. However, when considering a refractive index of an existing thin film material, a long wavelength transmission filter is Often, a design solution with a basic configuration is obtained.

[Third embodiment]
A third embodiment of the replacement films 12a and 13a made of a dielectric optical multilayer film will be described below.
This embodiment is an effective embodiment when the light source of the liquid crystal display element 21 is non-polarized light. As a result of optimization, the present example was as follows.
Substrate / (0.25H0.125L) (0.125L0.25H0.125L) ⁴ (0.125L0.25H) / Substrate However, the refractive index of the substrate is 1.75, the refractive index of the high refractive index layer H is 2.30, low The refractive index of the refractive index layer L is 1.48, and the center wavelength λ is 1150 nm. The substrate used was N-LAF4 manufactured by SCHOTT. The high refractive index layer H was formed by adjusting any one of TiO ₂ , Ta ₂ O ₅ , and Nb ₂ O ₅ while adjusting the film forming conditions, and the low refractive index layer L was formed by forming SiO ₂ .

FIG. 11 shows the angular characteristics of the reflectance of this embodiment, FIG. 12 shows the wavelength characteristics of the reflectance with respect to the normal incident light, and FIG. 13 shows the wavelength characteristics of the reflectance with respect to the incident light of 60 °.
As shown in FIGS. 11, 12, and 13, according to this example, good characteristics can be obtained for both p-polarized light and s-polarized light.
When the configuration of the present embodiment is modeled, the following symmetric configuration is obtained.

Substrate / (Matching layer group I) ^k1 , (Symmetric layer group) ^k2 , (Matching layer II) ^k3 / Substrate Each layer group is made by repeatedly laminating low refractive index layer L and high refractive index layer H (LHL or HLH) ), And the reflectance is set to be increased with respect to incident light of 60 °. Since the central layer group tends to reflect normal incident light, the film thickness of each of the matching layer groups I and II is optimized and adjusted for the purpose of suppressing this reflection.

At the time of design, the number of laminations k1, k2, and k3 of each layer group of this model is increased or decreased according to the incident angle of light, the refractive index of the substrate, etc., and the film thickness of each layer of the matching layer groups I and II is adjusted. do it.
Also, when the relationship with one substrate is different from the relationship with the other substrate (when the refractive index of the two substrates is different, or when the adhesive layer is interposed only between the one substrate, etc.) In this case, the number of stacking of the matching layer groups I and II and the film thickness of each layer may be adjusted individually.

At present, techniques for optimizing the film thickness by computer and automatic synthesis of the film structure are also widespread. When this method is used, the obtained design solution may slightly deviate from the basic configuration described above. However, it can still be regarded as a partial adjustment of the basic configuration (a modification of the basic configuration).
[Fourth embodiment]
Hereinafter, a fourth embodiment of the replacement films 12a and 13a made of a dielectric optical multilayer film will be described.

  This embodiment is an effective embodiment when the light source of the liquid crystal display element 21 is polarized. Further, the present embodiment is an embodiment to which a technique for automatically synthesizing a film configuration by a computer is applied. Table 1 shows the film configuration of this example.

表１に示すとおり、全層数は１９、基板の屈折率は１．５６、高屈折率層Ｈの屈折率は２．２０、低屈折率層Ｌの屈折率は１．４６、中心波長λは５１０ｎｍである。基板はＳＣＨＯＴＴ社製Ｎ−ＢＡＫ４を用い、高屈折率層Ｈは第１実施例と同じものを用い、低屈折率層ＬはＳｉＯ₂を用い、成膜条件を調整して形成した。

As shown in Table 1, the total number of layers is 19, the refractive index of the substrate is 1.56, the refractive index of the high refractive index layer H is 2.20, the refractive index of the low refractive index layer L is 1.46, the center wavelength λ Is 510 nm. The substrate was N-BAK4 manufactured by SCHOTT, the same high refractive index layer H as in the first example was used, and the low refractive index layer L was formed using SiO ₂ with the film forming conditions adjusted.

FIG. 14 shows the angular characteristics of the reflectance of this embodiment, FIG. 15 shows the wavelength characteristics of the reflectance with respect to the normal incident light, and FIG. 16 shows the wavelength characteristics of the reflectance with respect to the incident light of 60 °.
As shown in FIGS. 14, 15, and 16, good characteristics can be obtained according to this embodiment. In particular, as shown in FIG. 15, the transmittance for vertically incident light is particularly improved.
[Fifth embodiment]
The fifth embodiment of the replacement films 12a and 13a made of a dielectric optical multilayer film will be described below.

  This embodiment is an effective embodiment when the light source of the liquid crystal display element 21 is non-polarized light. Further, the present embodiment is an embodiment to which a technique for automatically synthesizing a film configuration by a computer is applied. The film configuration of this example is as shown in Table 2.

表２に示すとおり、全層数は４０、基板の屈折率は１．５６、高屈折率層Ｈの屈折率は２．２０、低屈折率層Ｌの屈折率は１．３８４５、中心波長λは５１０ｎｍである。基板はＳＣＨＯＴＴ社のＮ−ＢＡＫ４を用い、高屈折率層Ｈは先の実施例と同じものを用いた。低屈折率層Ｌは、ＭｇＦ₂、ＡｌＦ₃の何れかを成膜条件を調整して形成している。

As shown in Table 2, the total number of layers is 40, the refractive index of the substrate is 1.56, the refractive index of the high refractive index layer H is 2.20, the refractive index of the low refractive index layer L is 1.3845, the center wavelength λ Is 510 nm. The substrate used was N-BAK4 manufactured by SCHOTT, and the high refractive index layer H was the same as in the previous example. The low refractive index layer L is formed of MgF ₂ or AlF ₃ by adjusting the film forming conditions.

FIG. 17 shows the angular characteristics of the reflectance of this embodiment, FIG. 18 shows the wavelength characteristics of the reflectance with respect to the normal incident light, and FIG. 19 shows the wavelength characteristics of the reflectance with respect to the incident light of 60 °.
As shown in FIG. 17, FIG. 18, and FIG. 19, according to this embodiment, good characteristics can be obtained. In particular, as shown in FIGS. 18 and 19, the transmittance for vertically incident light and the reflectance for 60 ° incident light are improved.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. This embodiment is an embodiment of an eyeglass display. Here, differences from the first embodiment will be mainly described.
FIG. 20 is a schematic cross-sectional view obtained by cutting the optical system portion of the eyeglass display along the observer's horizontal plane. As shown in FIG. 20, the optical system portion of the present eyeglass display includes an image introduction unit 2 and a single substrate 11 (the image introduction unit 2 includes a liquid crystal display element 21 and a lens 22, and the substrate 11 is The introduction mirror 11a and the half mirror 11b are installed inside.).

In the present eyeglass display, a reflection enhancing film 22a is provided in close contact with each of the observer-side surface and the external-side surface of the substrate 11.
The reflection enhancement film 22a has at least the same function as the substitution films 12a and 13a (the same function as the air gap). That is, the reflection enhancement film 22a is reflective to the display light beam L1 (in this case, visible light incident near an incident angle of 60 °) that should be reflected from the inside of the substrate 11 and should be transmitted through the substrate 11. L1 and the external light flux L2 (here, visible light incident near an incident angle of 0 °) are transmissive.

However, the incident angle range θg of visible light that can be reflected by the reflection enhancing film 22a is larger than that of the replacement films 12a and 13a. Specifically, the lower limit of the incident angle range θg is It is smaller than the critical angle θ _c (≈40 °), for example, set to 35 °, etc. (Note that the upper limit of the incident angle range θg is around 90 ° as in the case of the substitution films 12a and 13a and the substrate 11 in the air. And less than 90 °).

The incident angle range θg of the display light beam 11 that can be reflected on the inner surface of the substrate 11 provided with the reflection enhancement film 22a is expanded more than when the substrate 11 is alone in the air. If the incident angle range θg is enlarged, the angle of view of the image that can be observed by the observation eye is enlarged.
If the lower limit of the incident angle range θg of visible light that can be reflected by the reflection enhancement film 22a is too small, the following problem may occur. That is, a part of the external light beam L2 cannot pass through the reflection enhancing film 22a, and the visibility of the external environment is deteriorated, or a part of the display light beam L1 deflected by the half mirror 11b is transferred from the substrate 11 to the outside (exit pupil). There is a possibility of loss due to the inability to inject. For this reason, the lower limit of the incident angle range θg of visible light that can be reflected by the reflection enhancing film 22a is between 0 ° and θ _c in consideration of the angle of view of the display light beam L1 and the incident angle when it is internally reflected. It needs to be set to an appropriate value.

The reflection enhancing film 22a having such characteristics is constituted by a dielectric optical multilayer film, HOE (holographic optical element), or the like. Among these, the details of the configuration of the reflection enhancement film 22a using the dielectric optical multilayer film will be described in an embodiment described later. The manufacturing method of the HOE is basically the same as the manufacturing method described in the first embodiment (see FIG. 4).
However, in this manufacturing method, as shown in FIG. 21, the auxiliary prism 34 only needs to be inserted into one of the laser beams incident on the photosensitive material 35 (because the reflection enhancement film 22a of this embodiment is in contact with 2). Because one of the two media is air.)

Further, the value of the angle θ (incident angle of the laser beam with respect to the hologram photosensitive material 35) in the optical system of FIG. 21 is set to the central incident angle range of the light that the reflection enhancing film 22a should exhibit reflectivity.
Again, since the incident angle and wavelength of light that the reflection enhancing film 22a should exhibit reflectivity are not one type, the photosensitive material 35 is subjected to multiple exposure while changing the angle θ and the wavelength of the laser beam as necessary. become.

Further, when a resin-based material (resin sheet) is used as the hologram photosensitive material 35, a large area HOE can be manufactured at a low cost. Further, if the HOE is a resin sheet, it is only necessary to affix the HOE to the eyeglass display substrate 11 so that the practical value is high in terms of low cost and mass production.
In addition, an optical multilayer film made of a metal film, a semiconductor film, or the like may be used for the reflection enhancement film 22a of the present embodiment. However, the dielectric optical multilayer film is more preferable than the optical multilayer film because it absorbs less light.

Each of the above optical function sections (dielectric optical multilayer film, HOE, and other optical multilayer films) is desirably selected and used as the reflection enhancement film 22a according to the specifications and cost of the eyeglass display.
[Sixth embodiment]
The sixth embodiment will be described below. This example is an example of a dielectric optical multilayer film suitable as the reflection enhancing film 22a of the eyeglass display of the second embodiment.

In the present embodiment, the light source of the liquid crystal display element 21 of the eyeglass display has an emission spectrum (the R color, the G color, and the B color have peaks), and the light source of the liquid crystal display element 21 Was assumed to be polarized. In this embodiment, a method of automatically synthesizing the film configuration by a computer is applied.
Table 3 shows the film configuration of the dielectric optical multilayer film of this example.

表３に示すとおり、全層数は５１、基板１１の屈折率は１．６０、高屈折率層の屈折率は２．３、低屈折率層の屈折率は１．４６である。基板はＳＣＨＯＴＴ社のＮ−ＳＫ１４を用い、高屈折率層は第１実施例と同じものを用いた。低屈折率層にはＳｉＯ₂を用い、成膜条件を調整して形成した。

As shown in Table 3, the total number of layers is 51, the refractive index of the substrate 11 is 1.60, the refractive index of the high refractive index layer is 2.3, and the refractive index of the low refractive index layer is 1.46. The substrate used was N-SK14 manufactured by SCHOTT, and the same high refractive index layer as in the first example was used. The low refractive index layer was formed by using SiO ₂ and adjusting the film forming conditions.

  FIG. 22 is a wavelength characteristic of reflectance with respect to light with a small incident angle (incidence angle of 0 ° to 20 °) of the dielectric optical multilayer film of this example. In FIG. 22, Ra (0 °), Ra (5 °), Ra (10 °), Ra (15 °), and Ra (20 °) are incident angles of 0 °, 5 °, 10 °, 15 °, It is the reflectance for incident light at 20 ° (both are average values of the reflectance for the s-polarized component and the reflectance for the p-polarized component of the incident light).

As is clear from FIG. 22, the dielectric optical multilayer film of the present example exhibits a transmittance of 80% or more over substantially the entire visible light region when the incident light has an incident angle of 0 ° to 20 °.
FIG. 23 shows the wavelength characteristics of the reflectance with respect to light with a large incident angle (incidence angles of 35 ° and 40 °) of the dielectric optical multilayer film of this example. In FIG. 23, Rs (35 °) and Rs (40 °) are reflectivities with respect to light having incident angles of 35 ° and 40 °, respectively (both reflectivities with respect to the s-polarized component of incident light).

As is apparent from FIG. 23, the dielectric optical multilayer film of the present example exhibits approximately 100% reflectivity over the entire visible light region as long as it is s-polarized light having an incident angle of 40 °. In addition, s-polarized light having an incident angle of 35 ° exhibits a reflectivity of 80% or more for each of R, G, and B components (460, 520, and 633 nm) in the visible light range.
FIG. 24 shows the angle characteristics of the reflectance with respect to light of each wavelength of the dielectric optical multilayer film of this example. In FIG. 24, Rs (633 nm), Rs (520 nm), and Rs (460 nm) are reflectivities for light (R color, G color, and B color) having wavelengths of 633 nm, 520 nm, and 460 nm, respectively (all are s-polarized light of incident light). Reflectance of component).

As is apparent from FIG. 24, the dielectric optical multilayer film of the present example has a reflection of 80% or more at an incident angle of 35 ° or more if it is light of each component of R color, G color, and B color in the visible light range. Showing gender.
As described above, the lower limit of the incident angle range θg of visible light (here, s-polarized R color, G color, and B color light) in which the dielectric optical multilayer film of the present embodiment exhibits reflectivity is 35 °. This is smaller than the critical angle θ _c = 38.7 ° of the substrate 11 (refractive index 1.60) assumed in this example.

Therefore, in the eyeglass display using the dielectric optical multilayer film of this embodiment as the reflection enhancement film 22a, the lower limit of the incident angle range θg of the display light beam L1 that reflects the substrate 11 on the inner surface is the critical angle θ _c = 38.7. It is also reduced by 3.7 ° from 35 ° to 35 °.
As a result, the eyeglass display can transmit the display light beam L1 having an incident angle range θg = 35 ° to 65 °, that is, the display light beam L1 having an angle of view of 30 °.

Further, as shown in FIG. 22, the dielectric optical multilayer film of the present example has a high transmittance for visible light of light with a small incident angle (0 ° to 20 °), so that the visibility of the outside of the eyeglass display is visible. Is reliably maintained, and there is no loss of the display light beam L1 incident on the exit pupil from the substrate 11.
[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. This embodiment is an embodiment of an eyeglass display. Here, differences from the first embodiment will be mainly described.

FIG. 25 is a schematic cross-sectional view obtained by cutting the optical system portion of the eyeglass display along the observer's horizontal plane. As shown in FIG. 25, the present eyeglass display includes a reflection enhancing film 22a instead of the replacement films 12a and 13a in the eyeglass display of the first embodiment (see FIG. 2).
This reflection enhancement film 22a has the same function as that of the second embodiment. That is, the lower limit of the visible light incident angle range θg at which the reflection enhancing film 22 a exhibits reflectivity is set lower than the critical angle θ _c of the substrate 11.

Therefore, this eyeglass display can obtain the effect of diopter correction as in the first embodiment and the effect of widening the angle of view as in the second embodiment.
Note that the manufacturing method in the case where the reflection enhancing film 22a is made of HOE is the same as the manufacturing method described in the first embodiment (see FIG. 4).
However, the value of the angle θ (incident angle of the laser beam with respect to the hologram photosensitive material 35) in the optical system of FIG. 4 is set to the central incident angle range of the light that the reflection enhancing film 22a should exhibit reflectivity.

Again, since the incident angle and wavelength of light that the reflection enhancing film 22a should exhibit reflectivity are not one type, the photosensitive material 35 is subjected to multiple exposure while changing the angle θ and the wavelength of the laser beam as necessary. become.
[Seventh embodiment]
The seventh embodiment will be described below. This example is an example of a dielectric optical multilayer film suitable as the reflection enhancing film 22a of the eyeglass display of the third embodiment.

In this embodiment, it is assumed that the light source of the liquid crystal display element 21 of the eyeglass display is polarized. In this embodiment, a method of automatically synthesizing the film configuration by a computer is applied.
Table 4 shows the film configuration of the dielectric optical multilayer film of this example.

表４に示すとおり、全層数は４４、基板１１の屈折率は１．５６、高屈折率層の屈折率は２．３、低屈折率層の屈折率は１．４６である。基板及び高屈折率層は、第２実施例と同じものを用い、低屈折率層はＳｉＯ₂を用い、成膜条件を調整して形成した。

As shown in Table 4, the total number of layers is 44, the refractive index of the substrate 11 is 1.56, the refractive index of the high refractive index layer is 2.3, and the refractive index of the low refractive index layer is 1.46. The substrate and the high refractive index layer were the same as those in the second example, and the low refractive index layer was formed using SiO ₂ while adjusting the film formation conditions.

FIG. 26 shows the wavelength characteristics of the reflectance with respect to light with a small incident angle (incident angle of 0 ° to 20 °) in the dielectric optical multilayer film of this example. In FIG. 26, Ra (0 °), Ra (10 °), and Ra (20 °) are reflectivities with respect to incident light at incident angles of 0 °, 10 °, and 20 °, respectively (all with respect to the s-polarized component of the incident light). The average value of the reflectance and the reflectance for the p-polarized component).
As is apparent from FIG. 26, the dielectric optical multilayer film of the present example exhibits a transmittance of 70% or more over substantially the entire visible light region when the incident light has an incident angle of 0 ° to 20 °.

FIG. 27 shows the wavelength characteristics of the reflectance with respect to light having a large incident angle (incident angle of 35 ° to 50 °) in the dielectric optical multilayer film of this example. In FIG. 27, Rs (35 °), Rs (40 °), and Rs (50 °) are reflectivities with respect to incident light at incident angles of 35 °, 40 °, and 50 °, respectively (all with respect to the s-polarized component of the incident light). Reflectance).
As is clear from FIG. 27, the dielectric optical multilayer film of the present example exhibits a reflectivity of 65% or more over substantially the entire visible light region as long as it is s-polarized light having an incident angle of 35 ° to 50 °. .

FIG. 28 shows the angle characteristics of the reflectance with respect to light of each wavelength of the dielectric optical multilayer film of this example. In FIG. 28, Rs (633 nm), Rs (520 nm), and Rs (460 nm) are reflectivities with respect to light (R color, G color, and B color) having wavelengths of 633 nm, 520 nm, and 460 nm, respectively (s polarization of incident light). Reflectance of component).
As is apparent from FIG. 28, the dielectric optical multilayer film of the present example has a light intensity of 65% or more at an incident angle of 35 [deg.] Or more for light of R, G, and B colors in the visible light range. Shows reflectivity.

That is, the lower limit of the incident angle range θg of visible light (here, s-polarized light with wavelengths of 633 nm, 520 nm, and 460 nm) in which the dielectric multilayer film of this example exhibits reflectivity is 35 °. This is smaller than the critical angle θ _c = 39.9 ° of the substrate 11 (refractive index 1.56) assumed in this example.
Therefore, in the eyeglass display using the dielectric optical multilayer film of this embodiment as the reflection enhancement film 22a, the lower limit of the incident angle range θg of the display light beam 11 that reflects the substrate 11 on the inner surface is the critical angle θ _c = 39.9. It is also reduced by 4.9 ° from 35 ° to 35 °.

In addition, as shown in FIG. 26, the dielectric optical multilayer film of the present example has a high transmittance for visible light of light with a small incident angle (0 ° to 20 °). Is maintained, and there is no loss of the display light beam L1 incident on the exit pupil from the substrate 11.
[Fourth Embodiment]
The fourth embodiment of the present invention will be described below with reference to FIG. In this embodiment, the above-described reflection enhancement film is applied to an eyeglass display of a type having a large exit pupil.

  FIG. 29 is a schematic cross-sectional view obtained by cutting the optical system portion of the eyeglass display of the present embodiment along the observer's horizontal plane. As shown in FIG. 29, in the present eyeglass display, a plurality of half mirrors 11b parallel to each other are arranged in a substrate 11 that internally reflects a display light beam L1. Each of the plurality of half mirrors 11 b reflects the display light beam L 1 that is internally reflected from the substrate 11 and that is incident within a predetermined angle range, and forms an exit pupil outside the substrate 11. The size of the exit pupil is larger by the number of the half mirrors 11b. Such a large exit pupil is advantageous in that the degree of freedom of the position of the pupil of the observation eye is increased.

In this eyeglass display, the reflection enhancing film 22a is formed in close contact with each of the observer-side surface and the external-side surface of the substrate 11. The reflection enhancement film 22a expands the incident angle range θg of the display light beam L1 that can reflect the substrate 11 on the inner surface in the same manner as in the above-described embodiment. Therefore, the angle of view of this eyeglass display is also enlarged.
[Fifth Embodiment]
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG. In this embodiment, the above-described reflection enhancing film is applied to another type of eyeglass display having a large exit pupil.

FIG. 30 is a schematic cross-sectional view obtained by cutting the optical system portion of the eyeglass display of the present embodiment along the observer's horizontal plane. As shown in FIG. 30, in the present eyeglass display, a plurality of half mirrors for forming a large exit pupil are arranged outside the substrate 11. The plurality of half mirrors are provided inside the substrate 12 arranged on the outside or observer side (in FIG. 30, outside). The plurality of half mirrors are of two types: a plurality of half mirrors 11b _L parallel to each other and a plurality of half mirrors 11b _R parallel to each other in different postures.

In addition, inside the substrate 11, an introduction mirror 11 a for deflecting the display light beam L 1 incident on the substrate 11 to an angle at which the inner surface can be reflected, and a folding mirror 11 c for folding the display light beam 11 reflected from the inner surface of the substrate 11 are provided. It is done. Due to the action of the folding mirror 11c, the display light beam L1 of the present eyeglass display reciprocates while reflecting the substrate 11 on the inner surface.
The posture of one half mirror 11b _L among the plurality of half mirrors is set so as to deflect the display light beam L1 in the forward path toward the observer side, and the posture of the other half mirror 11b _R is in the forward path. Is set to deflect the display light beam L1 toward the viewer. Therefore, the whole of the plurality of half mirrors 11b _L and 11b _R has a configuration in which roof type half mirrors are closely arranged.

In this eyeglass display, the reflection enhancing film is provided in close contact with each of the space between the substrate 12 and the substrate 11 and the surface of the substrate 11 on the viewer side.
Among these, the reflection enhancing film 22a on the observer side of the substrate 11 is the same as that of the above-described embodiment, and exhibits reflectivity with respect to the display light beam L1 that internally reflects the substrate 11.
On the other hand, the reflection enhancing film 22a ′ on the outside side of the substrate 11 is slightly different from that of the above-described embodiment, and exhibits semi-transparency with respect to the display light beam L1 that internally reflects the substrate 11.

That is, the reflection enhancement film 22a ′ exhibits transparency (total transparency) to the display light beam L1 and the external light beam L2 (here, visible light incident near an incident angle of 0 °) to be transmitted through the substrate 11. The display beam L1 (in this case, visible light incident near an incident angle of 60 °) to be internally reflected inside the substrate 11 is semi-transmissive. Then, the lower limit of the incident angle range showing the semi-transmissivity is set to a value smaller than the critical angle θ _c of the substrate 11.

Due to the translucency of the reflection enhancement film 22a ′, the display light beam L1 reciprocating in the substrate 11 enters the substrate 12 at a certain rate. The entered display light beam L1 is deflected toward the viewer by the plurality of half mirrors 11b _L and 11b _R in the substrate 12. The display light beam L1 deflected by the plurality of half mirrors 11b _L and 11b _R is transmitted through the reflection enhancing film 22a ′, the substrate 11 and the reflection enhancing film 22a to form a large exit pupil.

Further, the above-described reflection enhancement films 22a and 22a ′ expand the incident angle range of the display light beam L1 that can be internally reflected, as in the above-described embodiment. Therefore, the angle of view of the eyeglass display is also enlarged.
In the present eyeglass display, with folding mirror 11c are provided, but a half mirror is provided two, can be omitted and the folding mirror 11c and one of the half mirror 11b _R. However, it is preferable to provide them because the amount of light in the exit pupil is made uniform.

[Sixth Embodiment]
The sixth embodiment of the present invention will be described below with reference to FIG. In this embodiment, the above-described reflection enhancement film is applied to an eyeglass display of a type having a larger exit pupil.
FIG. 31 is an exploded view of the optical system portion of the eyeglass display of the present embodiment. As shown in FIG. 31, this eyeglass display is obtained by applying the same principle as the eyeglass display of the fifth embodiment and enlarging the exit pupil in two vertical and horizontal directions as viewed from the observer. . The eyeglass display also has a function of correcting the diopter of the observation eye.

  In FIG. 31, the display light beam L1 emitted from the image introduction unit 2 first enters the substrate 11 '. The substrate 11 ′ guides the display light beam L <b> 1 together with the substrate 12 ′, and expands the diameter of the display light beam L <b> 1 in the vertical direction viewed from the observer. The display light beam L1 enters the substrate 11. The substrate 11 guides the display light beam L1 together with the substrate 12, and expands the diameter of the display light beam L1 in the lateral direction viewed from the observation eye. The display light beam L1 forms an exit pupil near the observation eye.

Further, a substrate 13 is provided on the viewer side of the substrate 11, and the diopter correction of the observation eye with respect to the outside world is performed by the optical power of the surface on the observation eye side of the substrate 13 and the surface on the outside world side of the substrate 12. Is planned.
The same principle as that of the substrates 11 and 12 of the fifth embodiment is applied to each of the first optical system including the substrates 11 ′ and 12 ′ and the second optical system including the substrates 11 and 12. Further, the arrangement direction of each optical surface is rotated by 90 ° between the first optical system and the second optical system.

  That is, what is indicated by reference numeral 11a ′ inside the substrate 11 ′ is an introduction mirror that deflects the display light beam L1 incident on the substrate 11 ′ to an angle at which it can be internally reflected, and reference numeral 11c ′ indicates that the substrate 11 ′. Is a folding mirror that folds back the display light beam L1 that has been internally reflected. What is indicated by reference numeral 12a 'on the substrate 12' is a plurality of roof-type half mirrors arranged closely (see FIG. 30 for details).

  Reference numeral 11a inside the substrate 11 is an introduction mirror that deflects the display light beam L1 incident on the substrate 11 to an angle at which it can be internally reflected, and reference numeral 11c indicates a display in which the substrate 11 is internally reflected. This is a folding mirror that folds the light beam L1. What is indicated by reference numeral 12a in the substrate 12 is a plurality of roof-type half mirrors arranged closely (see FIG. 30 for details).

In the above eyeglass display, the location where the reflection enhancing film is provided is between the substrate 11 ′ and the substrate 12 ′, between the substrate 11 ′ and the substrate 13 ′, between the substrate 11 and the substrate 12, and between the substrate 11 and Each between the substrates 13.
However, the characteristic of the reflection enhancement film provided between the substrate 11 ′ and the substrate 12 ′ is required to transmit the display light beam L1 that internally reflects the substrate 11 ′ to the substrate 12 ′ at a certain ratio. Its characteristics are the same as those of the reflection enhancing film 22a ′ of the fifth embodiment.

In addition, the characteristic of the reflection enhancement film provided between the substrate 11 and the substrate 12 is also required to transmit the display light beam L1 that internally reflects the substrate 11 to the substrate 12 at a certain ratio. Its characteristics are the same as those of the reflection enhancing film 22a ′ of the fifth embodiment.
The above-described reflection enhancement film expands the incident angle range of the display light beam L1 capable of reflecting the substrate 11 ′ on the inner surface and the incident angle range of the display light beam L1 capable of reflecting the substrate 11 on the inner surface. Moreover, the enlargement direction on the substrate 11 ′ and the enlargement direction on the substrate 11 are rotated by 90 °.

Therefore, in the present eyeglass display, both the vertical field angle and the horizontal field angle are enlarged.
[Seventh Embodiment]
The seventh embodiment of the present invention will be described below with reference to FIG. In this embodiment, the above-described reflection enhancement film is applied to an eyeglass display of a type having many surfaces subjected to internal reflection.

  FIG. 32A is a schematic perspective view of an optical system portion of the present eyeglass display. FIG. 32B is a schematic cross-sectional view obtained by cutting the optical system portion along the observer's horizontal plane (ZX plane in FIG. 32A). FIG. 32C is a schematic cross-sectional view obtained by cutting the optical system portion at the front of the observer (YX plane in FIG. 32A). FIG. 32D is a diagram for explaining the angle of view of the present eyeglass display.

As shown in FIGS. 32A, 32B, and 32C, this eyeglass display adjusts the location and orientation of the introduction mirror 11a and the plurality of half mirrors 11b, and is used for internal reflection of the substrate 11. The total number of four surfaces is the surface on the viewer side, the surface on the outside world side, and two surfaces sandwiched between the two surfaces. These four surfaces are all flat surfaces.
FIG. 32 (d) shows two angles of view θb _−air and θa _−air of the image viewed from the observation eye of the present eyeglass display.

Of these, the angle of view θb _-air is the angle range θb of the display light beam L1 in which the two surfaces of the substrate 11 on the viewer side and the external surface side can be internally reflected, as shown in FIG. Determined by _-g .
_Further , as shown in FIG. _32C , the angle of view θa- _air is determined by the angle range θa- _g of the display light beam L1 in which the other two surfaces of the substrate 11 can be internally reflected.
This can be expressed as follows.

^{_{θa -air = sin -1 [n g}} sinθa -g]
^{_{θb -air = sin -1 [n g}} sinθb -g]
That is, the angle of view θb _−air and θa _−air become larger as the angle ranges θa _−g and θb _−g of the display light beam L1 that can reflect the substrate 11 on the inner surface are larger.
And in this eyeglass display, the locations where the reflection enhancing film is provided are four surfaces of the substrate 11 that are used for internal reflection. In FIGS. 32B and 32C, reference numeral 22a denotes a reflection enhancing film. The characteristics of the reflection enhancement film 22a are the same as those of the reflection enhancement film 22a in the above-described embodiment. The lower limit of the incident angle range of visible light that the reflection enhancement film 22a exhibits reflectivity is the critical angle θ _{c of the} substrate 11. Is lower than.

Therefore, the angle ranges θb _−g and θa _−g (FIGS. 32B and 32C) of the display light beam L1 that can reflect the substrate 11 on the inner surface are enlarged. As a result, the angles of view θb- _air and θa- _air (FIG. 32 (d)) of the present eyeglass display are also enlarged.
Note that the two reflection enhancement films 22a shown in FIG. 32C do not face the observation eye, and therefore do not need to transmit the external light flux.

Therefore, if the aspect ratio of the liquid crystal display element 21 is not 1: 1, the liquid crystal display element 21 may be arranged so that the longer angle of view corresponds to the angle of view θa- _air .
The substrate 11 of the present eyeglass display is a columnar base having a rectangular cross section, but a columnar base having a triangular cross section, a columnar base having a parallelogram cross section, and a columnar base having a pentagonal cross section. It is also possible to use other columnar substrates having different cross sections.

  In the above embodiment, only the eyeglass display has been described. However, the present invention is also applicable to a camera, binoculars, a microscope, a telescope finder, and the like.

It is an external view of the eyeglass display of 1st Embodiment. It is the schematic sectional drawing which cut | disconnected the optical system part of the eyeglass display of 1st Embodiment by the observer's horizontal surface. It is a figure which shows the angle characteristic of the reflectance of the glass substrate which exists in the air. It is a figure which shows the optical system which manufactures HOE35. It is a figure which shows the angle characteristic of the reflectance of 1st Example. It is a figure which shows the wavelength characteristic of the reflectance with respect to the normal incident light of 1st Example. It is a figure which shows the wavelength characteristic of the reflectance with respect to 60 degrees incident light of 1st Example. It is a figure which shows the angle characteristic of the reflectance of 2nd Example. It is a figure which shows the wavelength characteristic of the reflectance with respect to the normal incident light of 2nd Example. It is a figure which shows the wavelength characteristic of the reflectance with respect to the incident light of 60 degrees of 2nd Example. It is a figure which shows the angle characteristic of the reflectance of 3rd Example. It is a figure which shows the wavelength characteristic of the reflectance with respect to the normal incident light of 3rd Example. It is a figure which shows the wavelength characteristic of the reflectance with respect to the incident light of 60 degrees of 3rd Example. It is a figure which shows the angle characteristic of the reflectance of 4th Example. It is a figure which shows the wavelength characteristic of the reflectance with respect to normal incidence light of 4th Example. It is a figure which shows the wavelength characteristic of the reflectance with respect to the incident light of 60 degrees of 4th Example. It is a figure which shows the angle characteristic of the reflectance of 5th Example. It is a figure which shows the wavelength characteristic of the reflectance with respect to the normal incident light of 5th Example. It is a figure which shows the wavelength characteristic of the reflectance with respect to the incident light of 60 degrees of 5th Example. It is a schematic sectional drawing formed by cut | disconnecting the optical system part of the eyeglass display of 2nd Embodiment in an observer's horizontal surface. It is a figure which shows the optical system which manufactures HOE applied to the reflection enhancing film 22a of 2nd Embodiment. It is a wavelength characteristic of the reflectance with respect to the light (incident angle 0 degree-20 degrees) of the small incident angle of 6th Example. It is a wavelength characteristic of the reflectance with respect to the light (incidence angle 35 degrees, 40 degrees) of the large incident angle of 6th Example. It is an angle characteristic of the reflectance with respect to the light of each wavelength of the dielectric optical multilayer film of 6th Example. It is a schematic sectional drawing formed by cut | disconnecting the optical system part of the eyeglass display of 3rd Embodiment in an observer's horizontal surface. It is a wavelength characteristic of the reflectance with respect to the light (incident angle 0 degree-20 degrees) of the small incident angle of 7th Example. It is a wavelength characteristic of the reflectance with respect to the light (incidence angle 35 degrees-50 degrees) of the large incident angle of 7th Example. It is an angle characteristic of the reflectance with respect to the light of each wavelength of the dielectric optical multilayer film of 7th Example. It is a schematic sectional drawing formed by cut | disconnecting the optical system part of the eyeglass display of 4th Embodiment in an observer's horizontal surface. It is a schematic sectional drawing formed by cut | disconnecting the optical system part of the eyeglass display of 5th Embodiment in an observer's horizontal surface. It is an exploded view of the optical system part of the eyeglass display of 6th Embodiment. It is a figure for demonstrating the eyeglass display of 7th Embodiment.

Explanation of symbols

1: image display optical system, 2: image introduction unit, 11 and 12 and 13: substrate, 12a and 13a: substitution film, 22a and 22a ′: reflection enhancement film, 22: lens, 21: liquid crystal display element, 11a: introduction Mirror, 11b: Half mirror, 11c: Folding mirror

Claims (8)

A substrate through which a predetermined luminous flux can propagate;
An optical function unit provided in close contact with the surface of the substrate where the predetermined light beam that propagates is reachable, and having an interference function of reflecting the predetermined light beam and transmitting an external light beam arriving on the surface; With
The optical function unit is
An optical element comprising an optical multilayer film. The optical element according to claim 1,
The optical multilayer film is
An optical element characterized by being a dielectric optical multilayer film. The optical element according to claim 2,
The dielectric optical multilayer film is:
An optical element comprising at least two types of layers having different refractive indexes. In the optical element according to any one of claims 1 to 3 ,
The optical function unit is
An optical element characterized by reflecting the predetermined light beam having a specific polarization direction and transmitting a light beam having another polarization direction. In the optical element according to any one of claims 1 to 4 ,
The optical function unit is
The predetermined luminous flux reaching the surface at a critical angle under a condition where the luminous flux inside the substrate is totally reflected, or an incident angle larger than the critical angle, determined by the refractive index of the substrate and air, with a desired reflection characteristic. An optical element characterized by having a reflective property. The optical element according to any one of claims 1 to 5 , wherein a display light beam emitted from the image display element is propagated inside;
A combiner optical system comprising: a combiner that is provided in the optical element and reflects the display light beam propagating through the optical element in a predetermined direction and transmits the external light beam. The combiner optical system according to claim 6 ,
A combiner optical system comprising a dioptric lens for diopter correction provided in close contact with the optical function unit. An image display element;
Information display device characterized by comprising a combiner optical system according to claim 6 or claim 7.

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