CN1957269A - Optical elements and combiner optical systems and image-display units - Google Patents

Abstract

A light-propagating optical element having its internal reflection function and a see-through feature not damaged even if a member higher in reflective index than a surrounding medium is brought into close contact with the surface thereof. The optical element is characterized by comprising a plane substrate through the inside of which a predetermined light flux can propagate, and an optical function unit that is situated in close contact with the surface of the plane substrate the propagating predetermined light flux can reach, and has interfering or diffracting actions of reflecting the predetermined light flux and transmitting an external optical flux reaching the surface. This optical element, when used, can realize a combiner optical system that can easily mount functions such as a diopter correction, and an image display unit that can easily mount functions such as a diopter correction.

Description

Optical element, combiner optical system, and image display unit

technical field

The present invention relates to a light propagating optical element having see-through characteristics, a combiner optical system using the optical element, and an image display unit using the combiner optical system.

Background technique

A high refractive index material such as a glass substrate (transparent substrate) present in a low refractive index medium such as air, vacuum, or other gas causes light to be incident on it at angles greater than the critical angle only with transparent substrates. The internal reflection of the flux on it, while transmitting the light flux incident on it at an angle smaller than the critical angle, that is, it has internal reflection function and see-through characteristics.

One image display unit using such a transparent substrate as a light-propagating optical element is an eyeglass display (Patent Document 1, Patent Document 2, etc.).

In an eye display, a transparent substrate is placed in front of the viewer's eye, and the image transmission (carry) luminous flux from the image display element propagates in the transparent substrate to a position very close to the pupil of the viewing eye, and is superimposed on such as The external light flux is placed on a combiner of half mirrors in the transparent substrate and then incident on the pupil.

This glasses display enables the observer to simultaneously observe the image of the external field of view and the image of the image display element.

In order to realize the wide application of the glasses display, it is necessary to add the same function as the glasses (diopter correction) in addition to various other functions.

Patent Document 1: Japanese Unexamined Patent Application Publication No. 2001-264682

Patent Document 2: Japanese Internal Publication No. 2003-536102

Contents of the invention

The problem to be solved by the present invention

However, in an eye display utilizing the internal reflection function of a transparent substrate, it is impossible for the transparent substrate itself to have a curved surface, and thus it is impossible to have refractive power, and it is also impossible to paste another refractive member having a refractive index on the transparent substrate. (a plano-convex lens or a plano-concave lens having a refractive index equal to or greater than that of the transparent substrate).

Therefore, as a method of adding diopter correction, the idea currently considered is to attach such a refracting member on the surface of the transparent substrate via an air gap, but doing so involves various difficulties as described below.

For example, it is difficult to obtain mechanical strength while maintaining an air gap with required precision, and this method is accompanied by an increase in the number of parts, weight, thickness, etc., thereby increasing the complexity of the manufacturing process and increasing the cost. Also, depending on the positional relationship between the viewing eye and the transparent substrate, excessive light reflected by the air gap is sometimes incident on the viewing eye, impairing vision.

The present invention has been proposed in view of these problems, and an object of the present invention is to provide an optical element for light propagation having an internal reflection function and see-through characteristics, which will not damage the surface even if parts such as a refractor having a refractive index higher than that of the surrounding medium are in close contact with the surface thereof. The reflective features and perspective properties.

An object of the present invention is to provide a combiner optical system that can easily have a function such as diopter correction, and an image display unit that can easily have a function such as diopter correction.

means of solving problems

The optical element of the present invention is characterized in comprising a planar substrate capable of propagating predetermined luminous flux through the inside thereof; contact, and has the effect of reflecting the predetermined light flux, interfering with the external light flux reaching the surface, or diffracting the external light flux.

The optical functional unit may have a property of reflecting the predetermined light flux polarized along a specific direction and transmitting the light flux polarized along another direction.

The optical functional unit may have a property of reflecting a predetermined light flux reaching the surface at an incident angle equal to or greater than a critical angle with a desired reflective property. The critical angle is determined by the refractive indices of the planar substrate and air, and is the condition for total reflection of the luminous flux within the planar substrate.

Moreover, the optical functional unit may have a function of reducing the external light flux without increasing the light intensity attenuation of the predetermined light flux optical path.

The combiner optical system of the present invention is characterized in comprising: the optical element of the present invention and a combiner provided in the optical element in which image-carrying luminous flux emitted from a predetermined image display element propagates , and the optical element transmits to the viewing eye at least the external light flux directed from the external field of view with the planar substrate facing the viewing eye, the combiner reflection having propagated in the planar substrate in the direction of the viewing eye The image of the transmitted luminous flux, and transmits this external luminous flux.

The optical functional unit may be an optical film disposed on the surface of the planar substrate, and a second planar substrate may be disposed on the optical film.

Also, the second planar substrate may be a refractor for diopter correction.

Moreover, the optical functional unit may be provided on the outer surface of the planar substrate, and the entire optical system including the optical functional unit and the second planar substrate may have the ability to reduce the external light flux without increasing the image transmission light flux optical path Light intensity attenuation function.

The second substrate may have the property of absorbing visible light.

Moreover, the optical film may have the function of reducing the external light flux without increasing the light intensity attenuation of the image transmission light flux optical path.

Furthermore, the optical film can be fabricated from metals and/or dielectrics.

Also, the optical film can be fabricated using a holographic optical film.

Also, a second optical film may be provided on the surface of the second planar substrate.

Also, the second optical film can be fabricated from metal and/or dielectric.

Also, the second optical film can be made of a holographic optical film.

Also, the second optical film can be made of an electrochromic film.

Also, the second optical film can be made of a photochromic film.

Moreover, the entire optical system including the optical functional unit and the second planar substrate can reduce the external light flux incident on the combiner by a higher reduction ratio than the rest of the external light flux.

The combiner optical system of the present invention may further include a guide mirror for guiding the image transmission light flux emitted from the image display unit in a direction enabling the image transmission light flux to be reflected by the inner surface in the planar substrate.

The image display unit of the present invention is characterized by comprising: an image display element for emitting image-transmitting light flux for image display, and the combiner optical system of the present invention for guiding the image-transmitting light flux to the viewing eye.

The image display unit may further include a mounting member with which the combiner optical system is worn on the observer's head.

Effect of the present invention

According to the invention, the realized optical element for propagating light has an internal reflective function and see-through properties which are not impaired even if parts of the refractor with a higher refractive index than the surrounding medium are in close contact with its surface.

According to the present invention, a combiner optical system that can easily have a function such as diopter correction, and an image display unit that can easily have a function such as diopter correction are realized.

Description of drawings

Fig. 1 is the exterior view of the eye display of the first embodiment;

Fig. 2 is a schematic cross-sectional view of the optical system part of the glasses display of the first embodiment taken along the observer's horizontal plane;

Fig. 3 is a graph showing the angular characteristic of the reflectance of a glass substrate existing in air;

FIG. 4 is a view showing an optical system for manufacturing HOE35;

5 is a graph showing angular characteristics of reflectance of the first example;

6 is a graph showing wavelength characteristics of reflectance of vertically incident light of the first example;

7 is a graph showing wavelength characteristics of reflectance of incident light at 60° of the first example;

8 is a graph showing angular characteristics of reflectance of the second example;

9 is a graph showing wavelength characteristics of reflectance of vertically incident light of a second example;

10 is a graph showing wavelength characteristics of reflectance of incident light at 60° of the second example;

11 is a graph showing angular characteristics of reflectance of a third example;

12 is a graph showing wavelength characteristics of reflectance of vertically incident light of a third example;

13 is a graph showing wavelength characteristics of reflectance of incident light at 60° of a third example;

FIG. 14 is a graph showing a film structure of a fourth example;

15 is a graph showing angular characteristics of reflectance of a fourth example;

16 is a graph showing wavelength characteristics of reflectance of vertically incident light of a fourth example;

17 is a graph showing reflectance wavelength characteristics of 60° incident light of a fourth example;

FIG. 18 is a graph showing a film structure of a fifth example;

19 is a graph showing angular characteristics of reflectance of a fifth example;

20 is a graph showing wavelength characteristics of reflectance of vertically incident light of a fifth example;

21 is a graph showing reflectance wavelength characteristics of 60° incident light of a fifth example;

Fig. 22 is a schematic cross-sectional view of the optical system part of the glasses display of the second embodiment taken along the observer's horizontal plane;

FIG. 23 is a view showing an optical system for manufacturing an HOE applied to the enhanced reflective film 22a of the second embodiment;

Fig. 24 is a graph showing the thin film structure of the sixth example;

25 shows the wavelength characteristics of the reflectance of incident light at small incident angles (0° to 20° incident angle) of the sixth example;

26 shows wavelength characteristics of reflectance of incident light at large incident angles (35°, 40° incident angles) of the sixth example;

Fig. 27 shows the angular characteristics of the reflectance of the insulating optical multilayer film of the sixth example to the light of each wavelength;

Fig. 28 is a schematic cross-sectional view of the optical system part of the glasses display of the third embodiment taken along the observer's horizontal plane;

FIG. 29 is a graph showing a film structure of a seventh example;

30 shows wavelength characteristics of reflectance of incident light at small incident angles (0° to 20°) of the seventh example;

31 shows wavelength characteristics of reflectance of incident light at large incident angles (35° to 50°) of the seventh example;

Fig. 32 shows the angular characteristics of the reflectance of the insulating optical multilayer film of the seventh example to the light of the corresponding wavelength;

Fig. 33 is a schematic cross-sectional view of the optical system part of the glasses display of the fourth embodiment taken along the observer's horizontal plane;

Fig. 34 is a schematic cross-sectional view of the optical system part of the glasses display of the fifth embodiment taken along the observer's horizontal plane;

Fig. 35 is an exploded view of the optical system part of the glasses display of the sixth embodiment;

FIG. 36 is a view illustrating a glasses display of a seventh embodiment;

Fig. 37 is an appearance diagram of the glasses display of the eighth embodiment;

38 is a detailed view of the optical system of the glasses display of the eighth example;

Fig. 39 shows the wavelength characteristics of the refractive index of the silver layer;

Fig. 40 shows the wavelength characteristics of the extinction coefficient of the silver layer;

Fig. 41 shows the wavelength characteristics of reflectance and transmittance of the flat substrate 11 side of the light reducing film 20 of the eighth embodiment;

Fig. 42 shows the angular characteristics of reflectance and transmittance of the flat substrate 11 side of the light reducing film 20 of the eighth embodiment;

FIG. 43 is a diagram showing the film structure of the light reducing film 20 of the first modified example of the eighth embodiment;

FIG. 44 shows the wavelength characteristics of the transmittance of the light reducing film 20 of the first modified example of the eighth embodiment;

FIG. 45 is a diagram showing a film structure of a light reducing film 20 of a second modified example of the eighth embodiment;

FIG. 46 shows the wavelength characteristics of the transmittance of the light reducing film 20 of the second modified example of the eighth embodiment;

47 (a) is a view for explaining reflection on the air-side interface of the planar substrate 11, and (b) is a view for explaining reflection on the light-reducing film 20-side interface of the planar substrate 11;

FIG. 48 shows angular characteristics of the reflectance on the planar substrate 11 side of the light reducing film 20 of the first modified example and the second modified example;

FIG. 49 shows wavelength characteristics of the refractive index of titanium oxide (TiO ₂ );

FIG. 50 shows wavelength characteristics of the extinction coefficient of titanium oxide (TiO ₂ );

FIG. 51 is a diagram showing a film structure of a light reducing film 20 of a third modified example of the eighth embodiment;

FIG. 52 shows the wavelength characteristics of the transmittance of the light reducing film 20 of the third modified example of the eighth embodiment;

FIG. 53 shows the wavelength characteristics of the reflectance on the planar substrate 11 side of the light reducing film 20 of the third modified example of the eighth embodiment;

Fig. 54 is an appearance diagram of the glasses display of the ninth embodiment;

Fig. 55 is a detailed view of the optical system of the glasses display of the ninth embodiment;

Fig. 56 is a graph showing the film structure of the light-reducing film 20, 40 of the ninth embodiment;

FIG. 57 shows the wavelength characteristics of the transmittance of the central region of the light-reducing film 20, 40 and the wavelength characteristics of the transmittance of the peripheral region of the light-reducing film 20;

58 shows the wavelength characteristics of the transmittance of the central region of the light reducing film 20, 40 of the first modified example of the ninth embodiment;

FIG. 59 shows angular characteristics (central region characteristics) of reflection on the planar substrate 11 side of the light reducing film 20 of the first modified example of the ninth embodiment;

Fig. 60 is a view for explaining the first exposure of the manufacture of a holographic optical film;

Fig. 61 is a view for explaining the second exposure of the manufacture of the holographic optical film;

Fig. 62 is an example of the glasses display of the tenth embodiment;

Figure 63 is a detailed view of the optical system of the glasses display

64 is a graph showing the relationship between the extinction coefficient k and the transmittance of a glass substrate having a refractive index of 1.50 and a thickness of 1 mm;

FIG. 65 shows the wavelength characteristics of the reflectance on the planar substrate 11 side of the first optical film 60;

FIG. 66 shows the angular characteristics of the reflectance of the first optical film 60 on the second planar substrate 70 side.

Detailed ways

【The first embodiment】

A first embodiment of the present invention will be described below with reference to FIGS. 1 , 2 , 3 and 4 .

This embodiment is an embodiment of the glasses display (corresponding to the image display unit in the claims).

First, the structure of the glasses display is described.

As shown in FIG. 1, the glasses display includes an image display optical system 1, an image input unit 2, a cable 3, and the like. The image display optical unit 1 and the image input unit 2 are supported by a support 4 similar to a spectacle frame, and are worn on the observer's head (the support 4 includes a temple 4a, a support ring 4b, a bridge 4c, etc.) .

This image shows that the optical system 1 has an appearance similar to a spectacle lens and its periphery is supported by the support ring 4b.

The image input unit 2 is supported by a temple 4a. The image input unit 2 is supplied with image signals and power from an external device via a cable 3 .

When the eyeglass display is worn, the image display optical system 1 is disposed in front of one eye of the observer (hereinafter, assumed to be the right eye and referred to as "observation eye"). The glasses display worn by the observed person will be described below according to the position of the observer and the viewing eyes.

As shown in FIG. 2, this image input unit 2 has: a liquid crystal display element 21 (corresponding to an image display element in the claims) that displays an image based on an image signal supplied via a cable 3; The objective lens 22.

The image input unit 2 emits image-transmitting light flux L1 (visible light) that exits from the objective lens 22 to the right end portion of the observer-side surface of the image display optical system 1 .

The image display optical system 1 includes a planar substrate 13, a planar substrate 11, and a planar substrate 12, which are superimposed in close contact in order from the viewer's side.

Planar substrate 13, planar substrate 11, and planar substrate 12 are each made of a material having a property of transmitting at least visible light (for example, optical glass).

Here, the planar substrate 11 is a planar-parallel plate that repeatedly causes internal reflection of the image-transmitting light flux L1 entering from the image input unit 2 on the outer surface 11-1 and the viewer's side surface 11-2 (corresponding to The planar substrate in the claim).

The planar substrate 12 is arranged on the outer side of the planar substrate 11 to correct the diopter of the observed eye. The planar substrate 12 is a lens whose outer side surface 12-1 is a flat surface and whose viewer side surface 12-2 is a curved surface.

The planar substrate 13 disposed on the observer side of the planar substrate 11 also functions to correct the diopter of the viewing eye. The flat substrate 13 is a lens whose outer surface 13-1 is flat and whose viewer-side surface 13-2 is curved.

In addition, on the surface 13 - 2 , the region through which the image transmission light flux L1 first passes is a plane, which does not have optical capability for the image transmission light flux L1 .

Also, on the inside of the planar substrate 11, a region on which the image-transmitting light flux L1 is first incident, there is formed a guide mirror 11a which changes the angle of the image-transmitting light flux L1 so that it can pass through the planar substrate 11. The angle reflected by the inner surface.

And, in this planar substrate 11, in the area facing the pupil of the observation eye, a half mirror 11b (corresponding to the synthesizer in the claims) is provided, which reflects the reflected light from the inner surface along the direction of the pupil. The image transmits light flux.

Instead of the half mirror 11b, an HOE (which stands for a hologram optical element) having a property of polarizing light matching a predetermined diffraction condition along a predetermined direction may be used. Also the combiner can have an optical function.

Here, between the planar substrate 12 and the planar substrate 11, a substitute film 12a is provided in close contact with both. Moreover, between the planar substrate 13 and the planar substrate 11, a substitute film 13a is provided in close contact with both (the substitute films 12a, 13a correspond to the optical functional unit in the claims).

Instead of the thin films 12a, 13a, each has a property of reflecting visible light incident thereon at an incident angle of approximately 60°, and transmitting visible light incident thereon at an incident angle of approximately 0°.

Hereinafter, the detailed arrangement of the corresponding surfaces of the image display optical system 1 will be described according to the condition of the image transmission light flux L1.

As shown in FIG. 2, since the image transmission luminous flux L1 emitted from the display screen of the liquid crystal display element 21 of this image input unit 2 (only the image transmission luminous flux of the viewing central angle is shown) enters with an incident angle of about 0° via the objective lens 22. The planar substrate 13, the image-transmitting light flux L1 is incident on the planar substrate 11 through the replacement film 13a.

The image-transmitting light flux L1 entering the planar substrate 11 is incident on and reflected by the guide mirror 11a at a predetermined incident angle. The reflected image-transmitting light flux L1 is incident on the substitute film 13a at an incident angle θ of about 60°, and thus is reflected on the substitute film 13a to be directed toward the substitute film 12a. The image-transmitted light flux L1 is also incident on the substitute film 12a at an angle of incidence θ, and is therefore also reflected on the substitute film 12a.

Consequently, the image-transmitting light flux L1 propagates in the direction to the left of the observer, further away from the image input unit 2, while being alternately and repeatedly reflected on the replacement films 12a, 13a.

Thereafter, this image-transmitting light flux L1 is incident on the half mirror 11b to be reflected in the direction of the pupil of the viewing eye.

The reflected image-transmitting light flux L1 is incident on the substitute film 13 a at an angle of incidence of approximately 0° and thus passes through it to be incident on the pupil of the viewing eye via the planar substrate 13 .

The external luminous flux L2 from the external field of view (far point) is incident on the substitute film 12a via the planar substrate 12 at an angle of incidence of approximately 0°, and thus passes through the substitute film 12a at an incident angle of approximately 0° via the planar substrate 11. Angular incidence on the substitute film 13a. The external light flux L2 passes through the replacement film 13 a to be incident on the pupil of the viewing eye via the planar substrate 13 .

Here, the shape of the outer surface 12-1 of the planar substrate 12 and the shape of the observer-side surface 13-2 of the planar substrate 13 are set so as to perform diopter correction of the viewing eye.

Furthermore, diopter correction of the observation eye for the external field of view is achieved by a combination of the shape of the surface 12-1 and the shape of the surface 13-2 disposed in the optical path of the external light flux L2. Diopter correction for the viewing eye of the image is achieved by the shape of the surface 13-2 arranged in the optical path of the image-transmitting luminous flux L1. In order to realize diopter correction for the viewing eye of the image, the position of the objective lens 22 along the optical axis direction and the position of the liquid crystal display element 21 along the optical axis direction are adjusted simultaneously.

In the glasses display described above, the elements provided in the optical path from the liquid crystal display element 21 to the pupil correspond to the combiner optical system in the claims.

Next, the alternative thin films 12a, 13a will be described in detail.

(1) Regarding total internal reflection in the planar substrate 11

In general, when the incident angle exceeds a critical angle _θc represented by the following expression (1), total internal reflection occurs in the planar substrate 11 disposed in the medium,

θ _C ＝arc sin[n _m /n _g ]......(1) where

n _m is the refractive index of the medium, and _ng is the refractive index of the planar substrate 11 . This expression (1) shows that, in order to apply to the existence of θ _C , it is necessary to make n _m <n _g .

Therefore, passing directly through the planar substrates 12, 13 on the surface of the planar substrate 11 will make the refractive index of the medium too high, which does not allow the existence of θ _C , so that the internal reflection function is destroyed.

On the other hand, if the gap is provided on the surface of the planar substrate 11, the low refractive index (n _m = 1.0) of the medium (air) enables it to perform the internal reflection function, because when the material of the planar substrate 11 is a general optical For glass BK7 ( _ng = 1.56), expression (1) gives a critical angle θ _C of about 40°.

Furthermore, when an air gap is used, the incident angle characteristic of the reflectance of the planar substrate 11 is shown in FIG. 3 .

(2) Regarding insulating optical multilayer films

The following relationship is found in the theory of insulating optical multilayer films.

The film structure (described below) of a symmetrical film made of an insulating optical multilayer film sandwiched between two planar substrates made of optical glass will be discussed below. Here, a symmetric thin film refers to a thin film structure in which various layers are stacked centrally symmetrically. A layer group as a unit is placed in parentheses, and its structure is shown in the parentheses (the application of the layer group is described below).

planar substrate/(0.125L0.25H0.125L) ^k /planar substrate, or

Planar substrate/(0.125H0.25L0.125H) ^k /planar substrate

In each layer group, H represents a high refractive index layer, L represents a low refractive index layer, the superscript k on the right of each layer group represents the number of layers in each layer group, and the number written before each layer group represents the number of layers in each layer group. The thickness of the optical layers on each layer for the center wavelength of light incident on each layer (which applies to the description below).

It is known that symmetrical thin films can be treated as equivalent single thin films (equivalent thin films) with virtual refractive indices, and the theory of symmetrical thin films and the equivalent refractive index of such thin films (equivalent refractive index) is described in detail in HA. "Thin-Film optical Filters 3 ^rd Edition" by Macleod et al., so a detailed description thereof is omitted here.

In this film structure, if the equivalent refractive index of the equivalent film for vertically incident light is set to be the same as that of the planar substrate 11, the equivalent film does not cause interfacial reflection of vertically incident light, so It has 100% transmittance for such light, but causes interfacial reflection of incident light at large incident angles, thus increasing the reflection of such light. The reason for this is because the apparent refractive index N of the dielectric generally changes according to the propagation angle θ of light in the dielectric.

N=ncosθ(s-polarized light)

N=n/cosθ(p-polarized light)

Note that n is the refractive index of the dielectric. Furthermore, the increase in reflectance is particularly pronounced for s-polarized light as a function of the angle of incidence.

(3) Regarding the structure of the replacement films 12a, 13a

Not compromising the internal reflection of the planar substrate 11 mentioned in (1) and the see-through properties (equal to external visibility) of the planar substrate 11 are necessary for the replacement films 12a, 13a. That is, they need to have a property of reflecting the image transmission light flux L1 and a property of transmitting the external light flux L2.

Accordingly, the alternative films 12a, 13a are configured so as to have the property of reflecting with high reflectance (preferably total reflection) light incident thereon at or at an angle greater than the critical angle determined by the planar substrate 11 and The difference in the refractive index between the air is determined.

In this embodiment, the properties of the replacement films 12a, 13a are set to "the property of reflecting visible light incident thereon at an incident angle of approximately 60° and transmitting visible light incident thereon at an incident angle of approximately 0°". Such properties can be obtained by the insulating optical multilayer film described in (2).

Therefore, in this embodiment, insulating optical multilayer films are used as substitute films 12a, 13a.

The method of constructing the replacement membranes 12a, 13a is as follows.

The structure of the replacement film 12a, 13a (the structure of the unit layer group, the number of overlaps, the thickness of each layer, the refractive index of each layer, the material of each layer, etc.) presents high reflectivity according to the incident angle of light (here 60° )optimize. At the same time, the refractive index of the planar substrate 11 is optimized. The basic structure of the alternative membranes 12a, 13a is the symmetrical membrane described in (2).

However, even when the theory described in (2) is simplified and applied, the obtained solution and the refractive index existing in the thin film material do not match each other, therefore, all or part of the following measures are employed in the configuration.

The first measure is to insert several layers (matching layers) on one side of the planar substrate 11, the purpose of which is to achieve matching with the planar substrate 11.

A second measure is to absorb the refractive index profile in the material and to fine-tune the spectral/angular properties of the reflection/transmission of the material during optimization.

A third measure is to break symmetry (allow asymmetry) as needed.

The fourth measure is the optimization of the structure and the automatic synthesis of the film structure by means of a computer using layer thickness.

A fifth measure is to construct the film so as to have a property for s-polarized light only (since insulating optical multilayer films have the property of increasing the amount of their reflectance with increasing angle of incidence, this property is particularly pronounced for s-polarized light) the desired characteristics.

A sixth measure is to structure the film so as to have the desired properties only for predetermined wavelengths.

Furthermore, the fifth measure is effective when the light source of the liquid crystal display element 21 shown in FIG. 2 is an s-polarized light source. The fifth measure can also be made effective in the case of a p-polarized light source if its polarization direction is rotated by means of a phase plate or the like. Restricting the direction of polarization is advantageous because the degree of freedom of construction is thereby enhanced.

The sixth measure is effective when the light source of the liquid crystal display element 21 shown in FIG. 2 emits light having a certain wavelength. Restricting the wavelength is advantageous because the degree of freedom of construction is thereby enhanced.

The effect of the glasses display will be described below.

In the glasses display, substitute films 12a, 13a are formed on the outside of the flat substrate 11 and on the viewer's side.

The properties of the replacement films 12a, 13a are arranged such that they reflect visible light incident thereon at an angle of incidence of approximately 60° and transmit visible light incident thereon at an angle of incidence of approximately 0°.

The planar substrate 11 sandwiched by these replacement films 12a, 13a can cause internal reflection of the image-transmitting light flux L1 and can transmit the external light flux L2 from the outer field of view (far point).

Therefore, even if the planar substrates 12 and 13 having the same refractive index as the planar substrate 11 are pasted, the internal reflection function and see-through characteristics of the planar substrate 11 are not impaired.

As a result, the spectacle display can have diopter correction with a simple method of sticking only the substrates 12, 13.

Furthermore, the use of light absorbing materials for the planar substrates 12, 13 enables the spectacle display to function as sunglasses. In cases where only sunglass functionality is necessary and no diopter correction is required, the planar substrates 12, 13 may be light-absorbing planar row plates.

(other)

In this embodiment, the image transmission luminous flux L1 is visible light, and the properties of the flat substrate 11 and the replacement films 12a, 13a are set to reflect visible light on the inner surface, but it should be noted that when the light source of the liquid crystal display element 21 has an emission spectrum , this property can be set such that the inner surface reflects at least light of its peak wavelength.

Moreover, in the glasses display of this embodiment, the diopter correction is realized through two planar substrates (planar substrates 11, 12) and two substitute films (substitute films 12a, 13a), but the diopter correction can be achieved through one planar substrate and an alternative film implementation.

Also, in this embodiment, insulating optical multilayer films are used as the substitute films 12a, 13a, but HOE may be used. The details of the structure of the alternative films 12a, 13a' using the insulating optical multilayer film will be described in Examples described later, and here, the method of manufacturing the HOE will be described below.

Figure 4 shows the optical system used to fabricate the HOE. This optical system produces an HOE that reflects with high reflectance an image-transmitting light flux L1 incident thereon at an angle of incidence θ.

A laser beam having a wavelength λ emitted from a laser light source 31 is split into two beams by a beam splitter 32 . The two separated laser beams are respectively expanded by two beam expanders 33 and then incident on the holographic photosensitive material 35 via two auxiliary prisms 34 respectively. The photosensitive material 35 is thus exposed. Here, the incident angle of the laser beam on the holographic material is set as θ. The photosensitive material 35 is developed to accomplish the HOE.

The completed HOE has properties of causing diffraction/reflection of light flux having a predetermined wavelength λ incident thereon at a predetermined angle θ, and completely transmitting light incident thereon at an incident angle of about 0°.

In addition, the incident angles and wavelengths of light corresponding to the reflective properties of the alternative films 12a, 13a are different, so the photosensitive material 35 is exposed multiple times when the angle θ and wavelength of the laser beam are varied as required.

Furthermore, using a resin-based material (resin sheet) as the photosensitive material 35 enables low-cost manufacture of an HOE having a large area. Moreover, if the HOE is a resin sheet, the HOE can be closely contacted with the planar substrate 11 of the glasses display by pasting the HOE, which has high practical value in terms of cost reduction and mass production.

Alternatively, a multilayer optical film made of a metal film, a semiconductor film, or the like may be used as each of the substitute films 12a, 13a of this embodiment. However, an insulating optical multilayer film is more preferred because it absorbs less light than such a multilayer optical film.

Preferably, the above-described optical functional units (insulating optical multilayer film, HOE and other multilayer optical films) are selectively used as replacement films 12a, 13a according to specs and costs displayed by the glasses.

first instance

A first example of the alternative films 12a, 13a made of an insulating optical multilayer film will be described below.

This example is an effective example when the light source of the liquid crystal display element 21 is a polarized light source. The basic structure of this example is as follows, for example

Planar substrate/(0.125L0.25H0.125L) ^k /planar substrate

The refractive index of the planar substrate was 1.74, the disposition rate of the high refractive index layer H was 2.20, and the refractive index of the low refractive index layer L was 1.48.

N-LAF35 manufactured by SCHOTT was used as a planar substrate, one of TiO ₂ , Ta ₂ O ₅ and Nb ₂ O ₅ was used to form the high-refractive index layer H under adjusted film deposition conditions, and SiO ₂ was used to form The low refractive index layer L.

In addition, an insulating optical multilayer film having such a basic structure is generally called a "short-wavelength transmission filter". It has a characteristic of exhibiting a high transmittance for light whose wavelength is shorter than a predetermined wavelength, and exhibits a high reflectance for light whose wavelength is longer than the predetermined wavelength.

Another characteristic of a general insulating optical multilayer film is that when light is obliquely incident thereon, its spectral characteristics shift to the short wavelength side according to the incident angle.

By combining these two properties. The transmission band of vertically incident light becomes matched with the entire visible spectrum (400-700 nanometers) in advance, and the basic structure is optimized so that when the incident angle reaches around the critical angle θ _C of the planar substrate 11, the long-wavelength side reflection band Matches the entire visible spectrum (400-700 nm).

Plane substrate/(0.125L0.28H0.15L)(0.125L0.25H0.125L) ⁴ (0.15L0.28H0.125L)/Plane substrate

The refractive index of the planar substrate is 1.56, 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 central wavelength λ is 850 nm.

N-BAK4 manufactured by SCHOTT was used as a _flat substrate, and the high-refractive index layer H was formed of one of _TiO2 , _Ta2O5 , and _Nb2O5 under adjusted film deposition conditions _.

In this example, FIG. 5 , FIG. 6 and FIG. 7 show the angular characteristic of reflectance for vertically incident light, the wavelength characteristic of reflectance, and the wavelength characteristic of reflectance for 60° incident light, respectively. In the drawings described below, Rs is a characteristic of s-polarized light, Rp is a characteristic of p-polarized light, and Ra is an average characteristic of s-polarized light and p-polarized light.

As shown in Fig. 5, the angular characteristic of the reflectance of this example matches well that of the glass substrate (see Fig. 3) when limiting the characteristic of s-polarized light. Also, as shown in FIG. 6, this example has a high transmittance for vertically incident visible light. Also, as shown in FIG. 7, this example has a reflectance of substantially 100% for incident light at 60° throughout substantially the entire visible light spectrum.

In this instance, for example, a matching layer is used to reduce fluctuations in the transmission band (wavelength range where the reflectance is low).

second instance

A second example of the alternative films 12a, 13a made of an insulating optical multilayer film will be described below.

This example is an effective example when the light source of the liquid crystal display element 21 is a polarized light source. The basic structure of this example is as follows, for example

Planar substrate/(0.125H0.25L0.125H) ^k /planar substrate

In addition, this structure is often called "long-band transmission filter". It has a characteristic of high transmittance for light whose wavelength is longer than a predetermined wavelength, and a characteristic of high reflectance for light whose wavelength is shorter than the predetermined wavelength.

As a result of optimization, this example has the following structure.

Planar substrate (0.3H0.27L0.14H) (0.1547H0.2684L0.1547H) ³ (0.14H0.27L0.3H)/planar substrate

The refractive index of the planar substrate was 1.56, the refractive index of the high refractive index layer H was 2.00, the refractive index of the low refractive index layer L was 1.48, and the center frequency λ was 750 nm.

One of ZrO ₂ , HfO ₂ , Sc ₂ O ₃ , Pr ₂ O ₆ , and Y ₂ O ₃ is used to form the high refractive index layer H under adjusted film deposition conditions. The same materials are used for the planar substrate and the low-refractive index layer L as in the previously described examples.

In this example, FIG. 8 , FIG. 9 , and FIG. 10 show angular characteristics of reflectance and wavelength characteristics of reflectance for vertically incident light, and wavelength characteristics of reflectance for 60° incident light.

As shown in FIGS. 8, 9 and 10, this example provides good characteristics for s-polarized light, which are substantially the same as those of the first example.

In this example, a long wavelength band transmission filter is used as the basic structure. However, according to the theory described in the first embodiment (2), the short-wavelength transmission filter is suitable, but according to the study of the refractive index existing in the thin film material, this method using the long-wavelength transmission filter Basic structures often provide design solutions.

third example

A third example of the alternative films 12a, 13a made of an insulating optical multilayer film is described below.

This example is an effective example when the light source of the liquid crystal display element 21 is not a polarized light source. As a result of optimization, this instance has the following structure

Plane substrate/(0.25H0.125L)(0.125L0.25H0.125L) ⁴ (0.125L0.25H)/Plane substrate

The refractive index of the planar substrate was 1.75, the refractive index of the high refractive index layer H was 2.30, the refractive index of the low refractive index layer L was 1.48, and the center frequency λ was 1150 nm.

N-LAF4 manufactured by SCHOTT was used as the planar substrate. The high refractive index layer H was formed using one of TiO ₂ , Ta ₂ O ₅ , and Nb ₂ O ₅ under adjusted film deposition conditions, while SiO ₂ was deposited to form the low refractive index layer L.

11 , 12 and 13 show the angular characteristics of reflectance for vertically incident light, the wavelength characteristics of reflectance, and the wavelength characteristics of reflectance for 60° incident light.

As shown in FIG. 11 , FIG. 12 and FIG. 13 , good characteristics for both p-polarized light and s-polarized light can be obtained according to this embodiment.

The structure of this example was molded into the symmetrical structure described below.

Planar substrate/(matching layer group I) ^k1 (symmetrical layer group) ^k2 (matching layer group II) ^k3 /planar substrate

Each layer set is fabricated with repeated overlapping low-refractive-index layers L · high-refractive-index layers H (LHL or HLH) and arranged to have increased reflectance for 60° incident light. The central layer group helps to reflect vertically incident light, therefore, in order to reduce this reflection, the layer thickness of each layer in matching layer groups I and II is adjusted by optimization.

In the construction, the number of stacked layers k1, k2, k3 of each layer group of this model is increased/decreased, and the layer thickness of each layer in matching layer groups I, II depends on the incident angle of light and the refractive index of the planar substrate adjust.

In the case where the relation to one planar substrate is different from the relation to the other planar substrate (e.g. where the two planar substrates differ in refractive index or where an adhesive layer is placed between this instance and one of the planar substrates Bottom), the number of stacked layers of matching layer groups I and II and the layer thickness of each layer can be adjusted individually.

Moreover, at present, the method of optimizing the structure of the layer thickness by computer and the method of automatic synthesis of the thin film structure is also widely used. When using this method, the resulting scheme sometimes deviates slightly from the basic structure described above. but. This can be considered as the basic structure with its adjusted components (modified basic structure).

Fourth instance

A fourth example of the alternative films 12a, 13a made of an insulating optical multilayer film is described below.

This example is an effective example when the light source of the liquid crystal display element 21 is a polarized light source. And this example is an example where the method of automatically synthesizing the thin film structure with a computer is applied thereto. The basic structure of this example is shown in Figure 14.

As shown in Figure 14, the total number of layers is 19, the refractive index of the planar 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, and the central wavelength λ is 510 nanometers .

N-BAK4 manufactured by SCHOTT was used as the planar substrate, and the same high-refractive-index layer H was used as in the first example. _SiO2 was used to form the low refractive index layer L under adjusted film deposition conditions.

15, 16, and 17 show the angular characteristics of the reflectance for vertically incident light, the wavelength characteristics of the reflectance, and the wavelength characteristics of the reflectance for 60° incident light in this example.

As shown in FIGS. 15, 16 and 17, according to this example, good characteristics can be obtained. In particular, as shown in FIG. 16, the transmittance for vertically incident light is greatly improved.

Fifth instance

A fifth example of the alternative films 12a, 13a made of an insulating optical multilayer film is described below.

This example is an effective example when the light source of the liquid crystal display element 21 is not a polarized light source. And this example is an example where the method of automatically synthesizing the thin film structure with a computer is applied thereto. The basic structure of this example is shown in Figure 18.

As shown in Figure 18, the total number of layers is 40, the refractive index of the planar 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, and the central wavelength λ is 510 nanometers .

N-BAK4 manufactured by SCHOTT was used as the planar substrate, and the same high-refractive-index layer H as in the first example was used, and one of _MgF2 and _AlF2 was used to form the low-refractive-index layer L.

19, 20, and 21 respectively show the angular characteristic of reflectance for vertically incident light, the wavelength characteristic of reflectance, and the wavelength characteristic of reflectance for 60° incident light in this example.

As shown in FIGS. 19, 20 and 21, according to this example, good characteristics can be obtained. In particular, as shown in FIGS. 20 and 21 , the transmittance for vertically incident light and the reflectance for 60° incident light are improved.

【Second Embodiment】

A second embodiment of the present invention will be described below with reference to FIGS. 22 and 23 . This embodiment is an embodiment of a glasses display. Here, differences from the first embodiment will be mainly described.

Fig. 22 is a schematic sectional view of the optical system part of the glasses display taken along the observer's horizontal plane. As shown in Figure 22, the optical system part of this glasses display comprises image input unit 2 and planar substrate 11 (this image input unit 2 has liquid crystal display element 21 and objective lens 22 installed therein, and this planar substrate 11 has guide mirror 11 and a half mirror 11b) installed therein.

In the glasses display, reinforced reflective films 22a are respectively provided on the viewer's side surface and the outside surface of the planar substrate 11 so as to be in close contact with the corresponding surfaces.

Each enhanced reflective film 22a has at least the same function as the replacement films 12a, 13a (same function as the air gap). Specifically, the enhanced reflective film 22a exhibits reflective properties (here, visible light incident with an incident angle of about 60°) to the pattern transmission light flux L1 that will be reflected on the inner surface in the planar substrate 11, and will pass through the planar substrate 11. The image-transmitting light flux L1 and the external light flux L2 (here, visible light incident at an incident angle of about 0°) of the substrate 11 exhibit a transmissive property.

However, the incident angle range of the visible light that the enhanced reflective film 22a can reflect is wider than the incident angle range that the alternative films 12a, 13a can reflect visible light. Specifically, the lower limit of the incident angle is set to be smaller than the critical angle θ _C of the planar substrate 11. (≈40°), for example, set it to 35°, etc. The upper limit of the angle of incidence [theta] _g , similarly to each of the alternative films 12a, 13a and the planar substrate 11 in air as a single element, is about 90[deg.].

The incident angle range θ _g of the image transmission luminous flux L1 reflected by the inner surface of the planar substrate 11 having the enhanced reflection film 22a thereon is larger than that when the planar substrate 11 exists in air as a single element. This increased incidence angle range θ _g results in an increased viewing angle of the image that can be observed by the viewing eye.

If the lower limit of the range of incident angles of visible light that the enhanced reflective film 22a can reflect is set too low, the following problems arise. That is, it is possible that part of the external light flux L2 cannot pass through the enhanced reflective film 22a, resulting in poor external visibility, or the image transmission light flux L1 polarized by the half mirror 11b cannot be emitted from the flat substrate 11 to the outside (outgoing light Pupil), resulting in attenuation. Therefore, the lower limit of the range of incident angles of visible light that can be reflected by the enhanced reflective film 22a must be set between about 0° _˜θC in consideration of the viewing angle of the image transmission light flux L1 and its incident angle during internal reflection.

Also, the enhanced reflection film 22a having such characteristics is made of an insulating optical multilayer film, HOE (Holographic Optical Element), or the like. The structure of the reflective enhancing film 22a using an insulating optical multilayer film will be described in detail in Examples described below. The method of manufacturing the HOE is basically the same as that described in the first embodiment (see FIG. 4).

However, in this manufacturing method, as shown in FIG. 23, it is necessary to insert the auxiliary prism 32 only in one of the laser beams incident on the photosensitive material (this is because the reflective film 22a contacted with the enhancement in this embodiment One of the two media is air).

And, in the optical system of Fig. 23, the value of angle θ (the incident angle of the laser beam incident on this holographic photosensitive material 35) is set to the incident angle of the light that falls on this enhanced reflective film 22a to which it exhibits reflective properties within range.

Here, the incident angle and wavelength of light corresponding to the reflective properties of the enhanced reflective film 22a are different, therefore, the photosensitive material 35 is exposed multiple times when the angle θ and wavelength of the laser beam vary.

Also, using a resin-based material (resin sheet) as the holographic photosensitive material 35 enables low-cost manufacture of an HOE having a large area. Also, if the HOE is a resin sheet, the HOE can be closely contacted with the flat substrate 11 of the glasses display only by pasting the HOE, which has high practical value in terms of cost reduction and mass production.

Also, as the enhanced reflective film 22a of this embodiment, a multilayer optical film made of a metal film, a semiconductor film, or the like can be used. However, insulating optical multilayer films absorb less light than such multilayer optical films and are thus more preferred.

It is desirable that the above-described optical functional units (insulating optical multilayer film, HOE, and other multilayer optical films) are selectively used as the enhanced reflective film 22a according to specs, cost, etc. of the glasses display.

Sixth instance

A sixth example will be described below. This example is an example of an insulating optical multilayer film suitable as the enhanced reflective film 22a of the eyeglass display of the second embodiment.

In this example, it is assumed that the light source of the liquid crystal display element 21 of the glasses display has an emission spectrum (having red, green, and blue peaks, respectively), and that the light source of the liquid crystal display element is a polarized light source. Also, in this example, a method of automatically synthesizing thin film structures with a computer is applied.

The film structure of the insulating optical multilayer film of this example is shown in FIG. 24 .

As shown in FIG. 24, the total number of layers is 51, the refractive index of the flat substrate 11 is 1.60, the refractive index of the high refractive index layer H is 2.3, and the refractive index of the high refractive index layer L is 1.46.

N-SK14 manufactured by SCHOTT is used as a flat substrate, TiO ₂ , Ta ₂ O ₅ or Nb ₂ O ₅ is used to form a high-refractive index layer H under adjusted film deposition conditions, and SiO ₂ is used under adjusted film deposition conditions Next, the low refractive index layer L is formed.

FIG. 25 shows wavelength characteristics of the reflectance of the insulating optical multilayer film of this example to light incident at a small incident angle (incident angle 0° to 20°). In Figure 25, Ra(0°), Ra(5°), Ra(10°), Ra(15°) and Ra(20°) are 0°, 5°, 10°, 15° and 20° (each is the average value of the reflectance of the s-polarized portion of the incident light and the reflectance of the p-polarized portion of the incident light) the reflectance of the incident light at the angle of incidence.

It is clear from FIG. 25 that the insulating optical multilayer film of this example exhibits a transmission property of 80% or more for incident light in the entire visible spectrum if the incident angle of the incident light is in the range of 0°-20° .

FIG. 26 shows wavelength characteristics showing the reflectance of the insulating optical multilayer film of this example to light having a large incident angle (incident angle 35°, 40°). In FIG. 26, Rs(35°) and Rs(40°) are the reflectances of light incident at incident angles of 35° and 40° (each is the reflectance for the s-polarized portion of the incident light).

As is clear from FIG. 26, the insulating optical multilayer film of this example exhibits substantially 100% reflective properties for s-polarized light in the entire visible spectrum if the incident angle of the incident light is 40°. Furthermore, it exhibits reflective properties of 80% or more for the corresponding parts of the red, green and blue (460, 520, 633 nm) of the visible spectrum for s-polarized light at an incident angle of 35°.

FIG. 27 shows angular characteristics showing the reflectance of the insulating optical multilayer film of this example to light having corresponding wavelengths. In FIG. 27, Rs(633nm) and Rs(520nm) and Rs(460nm) are the reflectances to light (red, green and blue) with 633nm, 520nm and 460nm, respectively ( Each is the reflectance for the s-polarized portion of the incident light).

As shown in FIG. 27, the insulating optical multilayer films of this example exhibit reflections of 80% or more for light in the corresponding portions of red, green and blue in the visible spectrum if their incident angles are 35° or more. nature.

As described above, 35° is the lower limit of the range of incident angles of visible light (here, red, green and blue s-polarized light) for which the insulating optical multilayer film of this example exhibits reflective properties. This angle is smaller than the critical angle θ _C of the planar substrate 11 assumed in this example, θ _C =38.7°.

Therefore, in the eyewear display utilizing the insulating optical multilayer film of this example as the enhanced reflective film 22a, the lower limit of the incident angle range θ _g of the image transmission light flux L1 reflected by the inner surface in the planar substrate 11 is smaller than the critical angle θ _C , θ _C =38.7°, which is 3.7° greater than 35°.

As a result, the eyeglasses display can transmit the image-transmitting light flux L1 incident at incident angles within the incident angle range θ _g , θ _g =35°-36°, that is, the image-transmitting light flux L1 has an observation angle of 30°.

Also, as shown in FIG. 25, the insulating optical multilayer film of this example has high transmittance to visible light incident at a small incident angle (0° to 20°), so that the external visibility of the glasses display can be ensured, and it can be viewed from a flat surface. The image-transmitting light flux L1 incident on the exit pupil of the substrate 11 is not attenuated.

[Third embodiment]

A third embodiment of the present invention will be described below with reference to FIG. 28 . This embodiment is an embodiment of a glasses display. Here, differences from the first embodiment are mainly described.

Fig. 28 is a schematic cross-sectional view of the optical system portion of the glasses display taken along the observer's horizontal plane. As shown in FIG. 28, the glasses display is constructed such that in the glasses display of the first embodiment (see FIG. 2), an enhanced reflective film 22a is provided instead of the films 12a, 13a.

Each enhanced reflective film 22a has the same function as that of the second embodiment. That is to say, the lower limit of the incident angle range of visible light for which the enhanced reflective film 22a exhibits reflectance is smaller than the critical angle θ _C of the planar substrate 11 .

Therefore, the glasses display can provide the effect of diopter correction similarly to the first embodiment, and in addition, can provide the effect of enlarging the viewing angle similarly to the second embodiment.

In the case where the enhanced reflective film is manufactured using HOE, its manufacturing method is the same as that described in the first embodiment (see FIG. 4).

But in the optical system of FIG. 4, the value of the angle θ (incident angle of the laser beam incident on the holographic photosensitive material) is set within the range of the incident angle of light to which the enhanced reflective film 22a exhibits reflective properties.

Here, the incident angle and wavelength of light corresponding to the reflective properties of the enhanced reflective film 22a are different, therefore, the photosensitive material is exposed multiple times when the laser beam angle θ and wavelength are changed as required.

Seventh instance

A seventh example will be described below. This example is an example of an insulating optical multilayer film suitable as the enhanced reflective film 22a of the eyeglass display of the third embodiment.

In this example, it is assumed that the light source of the liquid crystal display element 21 of the glasses display is a polarized light source. Also, in this example, a method of automatically synthesizing the thin film structure with a computer was applied.

The film structure of the insulating optical multilayer film of this example is shown in FIG. 29 .

As shown in FIG. 29, the total number of layers is 44, the refractive index of the flat substrate 11 is 1.56, the refractive index of the high refractive index layer H is 2.3, and the refractive index of the high refractive index layer L is 1.46.

The flat substrate and low-refractive-index layer are the same as in the fourth _{example, and TiO2, Ta2O5 or Nb2O5 is used to} form the high-refractive-index layer H under adjusted film deposition conditions _.

FIG. 30 shows wavelength characteristics of the reflectance of the insulating optical multilayer film of this example to light incident at a small incident angle (incident angle 0° to 20°). In FIG. 30, Ra(0°), Ra(10°) and Ra(20°) are 0°, 10° and 20° (each is the reflectance and the The average value of the reflectance of the p-polarized part of the incident light) The reflectance of light incident at the angle of incidence.

As is clear from FIG. 30, the insulating optical multilayer film of this example exhibits 70% or more of the incident light in the entire visible spectrum if the incident angle of the incident light is in the range of 0° to 20°. Transmission properties.

FIG. 31 shows wavelength characteristics of the reflectance of the insulating optical multilayer film of this example for light having a large incident angle (incident angle 35° to 50°). In Fig. 31, Rs(35°), Rs(40°), and Rs(50°) are the reflectances of incident light incident at angles of incidence of 35°, 40°, and 50° (each is for the incident light The reflectance of the s-polarization part).

As shown in FIG. 31, the insulating optical multilayer film of this example exhibited reflective properties of 65% or more for substantially the entire visible spectrum of light if the incident angle was 35° to 50°.

FIG. 32 shows the angular characteristics of the reflectance of the insulating optical multilayer film of this example to light having respective wavelengths. In Fig. 32 Rs(633nm) and Rs(520nm) and Rs(460nm) are the reflectance to light having 633nm, 520nm and 460nm (red, green and blue) respectively (each is reflectance for the s-polarized portion of incident light).

As shown in FIG. 32, the insulating optical multilayer film of this example exhibits reflection of 65% or more for each part of the red, green, and blue parts of the visible spectrum if its incident angle is 35° or more. nature.

That is, 35° is the lower limit of the incident angle range of visible light (here, s-polarized light having wavelengths of 663 nm, 520 nm, and 460 nm) for which the insulating optical multilayer film of this example exhibits reflective properties. This angle is smaller than the critical angle θ _C of the planar substrate 11 (refractive index 1.56) assumed in this example, θ _C =39.9°.

Therefore, in the glasses display utilizing the insulating optical multilayer film of this example as the enhanced reflective film 22a, the lower limit of the incident angle range θ _g of the image transmission luminous flux L1 reflected by the inner surface in the planar substrate 11 is less than 39.9° The critical angle θ _C is 35°, which is 4.9° smaller than the critical angle θ _C .

Also, as shown in FIG. 30, the insulating optical multilayer film of this example has high transmittance to visible light incident at a small incident angle (0° to 20°), so that the external visibility of the glasses display can be ensured, and it can be viewed from a flat surface. The image-transmitting light flux L1 incident on the exit pupil of the substrate 11 is not attenuated.

[Fourth embodiment]

A fourth embodiment of the present invention will be described below with reference to FIG. 33 . This embodiment is an embodiment of a glasses display. In this embodiment, the aforementioned enhanced reflective film is applied to an eyeglass display with a large exit pupil.

33 is a schematic cross-sectional view of the optical system portion of the glasses display taken along the observer's horizontal plane. As shown in FIG. 33, the glasses display has a plurality of half mirrors 11b parallel to each other provided in a flat substrate 11 in which image transmission light flux L1 is reflected by the inner surface. Each of the plurality of half mirrors 11b reflects light in the image-transmitting luminous flux incident at an incident angle within a predetermined angular range, which is surface-reflected in the planar substrate 11, and each half mirror 11b An exit pupil is formed outside the planar substrate 11 . Therefore, the size of the exit pupil is increased by providing the plurality of half mirrors 11b. Such a large exit pupil is advantageous in terms of enhancing the degree of freedom of the position of the pupil of the viewing eye.

In this glasses display, enhanced reflection films 22a are respectively formed on the viewer's side surface and the outside surface of the planar substrate 11 so as to be in close contact therewith. As in the above embodiments, the enhanced reflection film 22a increases the range of incident angles so that the image-transmitting light flux can be reflected from the inner surface in the planar substrate 11 . Therefore, the viewing angle of such glasses displays is increased.

[fifth embodiment]

A fifth embodiment of the present invention will be described below with reference to FIG. 34 . In this embodiment, the aforementioned enhanced reflective film is applied to an eyeglass display with a large exit pupil.

Fig. 34 is a schematic cross-sectional view of the optical system part of the glasses display taken along the observer's horizontal plane. As shown in FIG. 34 , in this eyeglass display, a plurality of half mirrors 11 b for forming a large exit pupil are provided outside a flat substrate 11 . The plurality of half mirrors are arranged in a planar substrate 12 which is arranged on the outside or on the viewer's side (outside in FIG. 4 ). Also, the plurality of half mirrors is composed of two types, namely, a plurality of half mirrors 11b _L parallel to each other and a plurality of half mirrors 11b _R parallel to each other and different in attitude from the plurality of half mirrors 11b _L .

Inside the planar substrate 11, a guide reflector 11a and a return mirror _11c are arranged, and the guide reflector 11a is used to polarize the image-transmitting light flux L1 incident on the planar substrate 11 to allow the image-transmitting light flux L1 to be transmitted by the inner surface Angle of reflection; the return mirror _11C returns the image-transmitting light flux L1 that has been reflected by the inner surface in the planar substrate 11 .

Among the plurality of half mirrors, the attitude of the half mirror 11b _L is set so that the image transmission light flux L1 is polarized toward the observer side on the forward path, and the attitudes of the other half mirrors 11b _R are set so that in the forward path The image-transmitting light flux L1 on the return path is polarized toward the viewer side. Therefore, the entire structure of the half mirrors 11b _L , 11b _R is a roof-shaped half mirror arranged so as to be closed to each other.

In this glasses display, an enhanced reflective film is disposed between the planar substrate 12 and the planar substrate 11, and on the observer-side surface of the planar substrate 11 so as to be in close contact therewith.

Wherein, the enhanced reflective film 22a on the viewer side of the planar substrate 11 is the same as the enhanced reflective film described above, and transmits the image reflected by the inner surface in the planar substrate 11. The luminous flux L1 exhibits reflective properties.

On the other hand, the enhanced reflective film 22a' on the outer side of the planar substrate 11 is slightly different from the above-described enhanced reflective film, and transmits light flux L1 to the image reflected by the inner surface in the planar substrate 11. exhibits semi-transmissive properties.

Specifically, the reflection-enhancing film 22a' exhibits a transmissive property (full transmission) to the image-transmitting luminous flux L1 and the external luminous flux L2 (here, visible light incident at an incident angle of about 0°) passing through the planar substrate 11, and The image-transmitting light flux L1 (here, visible light incident at an incident angle of about 60°) reflected by the inner surface in the planar substrate 11 exhibits a semi-transmissive property. The lower limit of the incident angle range of light exhibiting semi-transmissive properties is set to a value smaller than the critical angle θ _C of the planar substrate 11 .

A certain proportion of the image-transmitting light flux L1 reciprocating in the planar substrate 11 propagates toward the planar substrate 12 side due to the semi-transmissive property of the enhanced reflective film 22a'. The propagating image-transmitting light flux L1 is polarized toward the observer side by the plurality of half mirrors 11b _L , 11b _R in the planar substrate 12 . The image-transmitting light flux L1 polarized by the plurality of half mirrors 11b _L , 11b _R then passes through the enhanced reflective film 22a', planar substrate 11 and enhanced reflective film 22a to form a large exit pupil.

Also, similar to the above embodiment, the enhanced reflective film 22a, 22a' increases the range of incident angles so that the image transmission light flux L1 can be reflected by the inner surface similar to the image transmission light flux L1 of the above embodiment. Therefore, the viewing angle of the glasses display is also increased.

In this glasses display, the return mirror _11C and two kinds of half mirrors are provided, but it should be noted that the return mirror _11C and the half mirror _11bR may be omitted. However, providing these mirrors makes the light intensity uniform in the exit pupil and is therefore more preferred.

[Sixth embodiment]

A sixth embodiment of the present invention will be described below with reference to FIG. 35 . In this embodiment, the aforementioned enhanced reflective film is applied to an eyeglass display that still has a large exit pupil.

Fig. 35 is an exploded view of the optical system portion of the glasses display of this embodiment. As shown in FIG. 35 , the same principle as that of the glasses display of the fifth embodiment is applied to this glasses display, and when viewed from an observer, the exit pupil is expanded in both vertical and horizontal directions. And this glasses display also has a diopter correction function.

In FIG. 35, the image transmission light flux L1 emitted from the image input unit 2 is first incident on the planar substrate 11'. The planar substrate 11' and the planar substrate 12' guide the image-transmitting light flux L1, and expand the diameter of the image-transmitting light flux L1 in the vertical direction when seen from an observer. The image transmission light flux L1 is incident on the planar substrate 11 . The planar substrate 11 and the planar substrate 12 together guide the image-transmitting light flux L1 to expand the diameter of the image-transmitting light flux L1 in the horizontal direction when viewed from an observer.

And, the planar substrate 13 is arranged on the observer's side of the planar substrate 11, and the optical function of the viewing eye side surface of the planar substrate 13 and the optical function of the outer side surface of the planar substrate 12 are realized for external use. The field of view is diopter-corrected for the viewing eye.

The same principle as the planar substrates 11 , 12 of the first embodiment is used for the first optical system including the planar substrates 11 ′, 12 ′ and the second optical system including the planar substrates 11 , 12 . Also, the arrangement direction of the optical surfaces of the first optical system is rotated by 90° from the arrangement direction of the optical surfaces of the second optical system

Specifically, in the planar substrate 11', reference numeral 11a' denotes a guide mirror that polarizes the image-transmitting light flux L1 incident on the planar substrate 11' to a point where the image-transmitting light flux L1 is reflected by the inner surface. angle, reference numeral 11c' denotes a return mirror that returns the image-transmitting light flux L1 that has been reflected by the inner surface in the planar substrate 11'. In the planar substrate 12', reference numeral 12a' denotes a plurality of roof-shaped half mirrors arranged to close each other (refer to FIG. 34 for details).

In the planar substrate 11, reference numeral 11a denotes a guide mirror that polarizes the image-transmitting light flux L1 incident on the planar substrate 11 to an angle at which the image-transmitting light flux L1 is reflected by the inner surface, and reference numeral 11c denotes a return mirror that returns the image-transmitting light flux L1 that has been reflected by the inner surface in the planar substrate 11 . In the planar substrate 12, reference numeral 12a denotes a plurality of roof-shaped half mirrors arranged to close each other (refer to FIG. 34 for details).

In the above-mentioned glasses display, the enhanced reflective film is arranged between the planar substrate 11' and the planar substrate 12', between the planar substrate 11' and the planar substrate 13', and the planar substrate 11 and the planar substrate 12 Between, between the planar substrate 11 and the planar substrate 13.

However, the enhanced reflective film disposed between the planar substrate 11' and the planar substrate 12' needs to have a certain proportion of the image-transmitting light flux L1 reflected by the inner surface in the planar substrate 11' to propagate through the planar substrate. sheet 11' to planar substrate 12' characteristics. This characteristic is the same as that of the enhanced reflective film 22a' of the fifth embodiment.

The enhanced reflective film arranged between the planar substrate 11 and the planar substrate 12 also needs to have a certain proportion of the image transmission light flux L1 reflected by the inner surface in the planar substrate 11 to propagate through the planar substrate 11 to the planar substrate. Properties of sheet 12. This characteristic is the same as that of the enhanced reflective film 22a' of the fifth embodiment.

The above-mentioned enhanced reflective film increases the scope of the incident angle, so that the image transmission luminous flux L1 can be reflected by the inner surface of the planar substrate 11 ′, and increases the scope of the incident angle so that the image transmission luminous flux L1 can be reflected by the inner surface of the planar substrate 11 reflection. Also, increase the direction at the planar substrate 11' and increase the direction at the planar substrate 11 so that the difference between the two directions is 90°.

Therefore, in such glasses displays, both the viewing angle in the vertical direction and the viewing angle in the horizontal direction are increased.

[Seventh embodiment]

A seventh embodiment of the present invention will be described below with reference to FIG. 36 . In this embodiment, the aforementioned enhanced reflective film is applied to an eyeglass display where many surfaces are used for internal reflection.

Fig. 36(a) is a schematic perspective view of the optical system portion of the glasses display. FIG. 36( b ) is a schematic sectional view of the optical system part taken along a horizontal plane (ZX plane of the observer in FIG. 36( a )). Fig. 36(c) is a schematic sectional view of the optical system part taken along a plane in front of the observer (YX plane in Fig. 36(a)). Fig. 36d is a view for explaining the viewing angle of the glasses display.

As shown in Fig. 36 (a), (b) and (c), in this glasses display, by adjusting the setting position and attitude of the guide mirror 11a and the plurality of half mirrors 11b, a total of 4 of the planar substrate 11 A surface is used for internal reflection. The four surfaces are a viewer's side surface, an outside surface, and two surfaces sandwiched between the two surfaces. Furthermore, these four surfaces are all flat surfaces.

Fig. 36(d) shows viewing angles θb _-air , θa _-air along two directions of the image displayed by the glasses when viewed from an observer.

In addition to these, the observation angle θb _-airr is determined by the angle θb _-g at which the image-transmitting luminous flux L1 can be reflected by the inner surface on both surfaces, which are the observer-side surface of the planar substrate 11 and The outer surface, as shown in Fig. 36(b).

The viewing angle ? _a-air is determined by the angle ?a _-g at which the image-transmitting light flux L1 can be reflected by the inner surface on both surfaces of the flat substrate 11, as shown in FIG. 36(c).

They are represented by the following expressions

θa _-air = sin ^-1 [n _g sin θa _-g ]

θb _-air = sin ^-1 [n _g sin θb _-g ]

That is to say, when the angle ranges θa _{-g ,} θb -g in which the image transmission light flux L1 can be reflected on the inner surface of the planar substrate 11 become larger, the viewing angles θa _-air , _{θb -air also} become larger.

In the glasses display, enhanced reflective films are provided on the four surfaces of the planar substrate 11 for internal reflection. In Fig. 36b, c, reference numeral 22a denotes an enhanced reflective film. The characteristics of the enhanced reflective film 22a are the same as those of the enhanced reflective film 22a in the above-mentioned embodiment, and the lower limit of the range of incident angles of the visible light to which the enhanced reflective film 22a exhibits reflective properties is lower than the plane The critical angle θ _C of the substrate 11 .

Therefore, the range of angles θa _-g , _{θb -g} in which the image-transmitting light flux L1 can be reflected by the inner surface in the planar substrate 11 (Fig. 36b,c) is increased. As a result, the viewing angles θa _-air , θb _-air ( FIG. 36d ) of the glasses display are also increased.

In addition, the two enhanced reflective films 22a shown in Figure 36(c) do not face the viewing eye and therefore do not need to transmit external light flux. Therefore, preferably, a metal film made of silver, aluminum, etc. is used for each of the two enhanced reflective films instead of the aforementioned insulating optical multilayer film or HOE. The use of the metal thin film enables the observation angle θa _-air to be larger than the observation angle θb _-air .

Therefore, if the aspect ratio of the liquid crystal display element 21 is not 1:1, the liquid crystal display element 21 is preferably arranged such that the observation angle on the longer side corresponds to the observation angle θa _-air .

In addition, the planar substrate 11 of the glasses display is a columnar substrate with a rectangular cross-section, but it is also possible to use a cylindrical substrate with a different cross-section, such as a cylindrical substrate with a triangular cross-section, a parallelogram cross-section Cylindrical substrates, cylindrical substrates with pentagonal cross-sections.

[eighth embodiment]

An eighth embodiment of the present invention will be described below with reference to FIGS. 37 , 38 , 39 , 40 , 41 and 42 . This embodiment is an embodiment of a glasses display. Differences from the first embodiment are mainly described here.

Fig. 37 is an external view of the glasses display. The coordinate system in FIG. 37 is a right-hand-ruled XYZ Cartesian coordinate system in which the X direction points downward and the Y direction points right when viewed from an observer wearing glasses on the head. In the following description, directions represented by an XYZ coordinate system or directions represented by left, right, up and down as viewed from an observer will be used as necessary.

As shown in FIG. 37 , the image display optical system 1 of the glasses display has a reduction function of reducing the amount of external light guided from the external field of view to the observation eye (right eye of the observer).

Moreover, in order to balance the light intensity of the external luminous flux guided from the external field of view to the observing eye and the light intensity of the external luminous flux guided from the external field of view to the non-observing eye (the left eye of the observer), and in order to balance the left and right sides of the glasses display Right appearance, the front of the non-observation eye side also has a light reducing function similar to the image display optical system 1, and a flat substrate 5 having the same appearance as the image display optical system 1 is attached to the front of the non-observation eye. This should not be used where there is no need to balance external light flux and no need to balance appearance.

38 is a detailed view of the optical system of the glasses display and an exploded schematic sectional view of the optical system portion of the glasses display taken along a plane parallel to the YZ plane.

In FIG. 38, reference numeral 20a denotes an illumination optical system including an LED light source, a reflection mirror, etc., which is not shown in the first embodiment.

As shown in FIG. 38, an image display optical system 1 includes a planar substrate 11 having a transmissive property for at least visible light. At a predetermined position of the planar substrate 11, a guide mirror 11a and a half mirror 11b similar to the first embodiment are arranged in a predetermined posture. As in the first embodiment, a possible alternative for the half mirror 11b is a polarizing optical film, such as a polarizing beam splitter or a holographic optical film that transmits external light flux including visible light.

On the outer surface 1b of the planar substrate 11, a light reduction film 20 is formed which reduces the external light flux L2 at a predetermined reduction ratio. The function of the light reducing film 20 is to reduce the brightness of the external image by a predetermined ratio.

Specific examples of the light reducing film 20 will be described below.

As a material of a general light-reducing film, a metal element such as aluminum (Al), chromium (Cr), tungsten (W) or rhodium (Ro), or Inconel or the like is used.

However, these materials have light-absorbing properties (absorbance), so if the light-reducing film 20 is provided on the planar substrate 11 regardless, a certain amount of image transmission light flux L1 reflected by the inner surface in the planar substrate 11 will be The light reducing film 20 absorbs. That is, the light intensity of the light path of the image transmission light flux L1 will be greatly lost.

Therefore, in order to prevent attenuation of light intensity, a two-layer film constituted by overlapping of a silver (Ag) film and a dielectric film is used as the light-reducing film 20 in this embodiment. The basic structure of light reduction film is as follows:

Flat substrate/Ag/0.25L/air, where

Ag: silver (silver layer),

L: low refractive index dielectric (L layer), and

Numerical value to the left of the L layer: layer thickness of the L layer (central wavelength of the used wavelength range).

In this basic structure, the L layer is used to protect the surface of the silver layer from being eroded by air and to increase the reflectance to light incident at a large incident angle.

The details (specifications) of the light reduction film 20 are as follows:

Set Transmittance: 30% (for 0 degree incident angle),

Central wavelength λ _C : 500 nm,

Refractive index of planar substrate: 1.56,

layer thickness of the silver layer: 30 nm, and

Refractive index of L layer: 1.46.

In addition, as a single element, the optical constants of the silver layer are shown in Fig. 39 and Fig. 40 . FIG. 39 shows the wavelength characteristics of the refractive index of the silver layer as a single element, and FIG. 40 shows the wavelength characteristics of the extinction coefficient of the silver layer as a single element.

The wavelength characteristics (incident angle 0°, 45°) of the reflectance and transmittance of the light-reducing film 20 on the flat substrate 11 side are shown in FIG. 41 . Also, the angular characteristics (wavelength 550 nm) of the reflectance and transmittance of the light reducing film 20 on the flat substrate 11 side are shown in FIG. 42 .

In FIGS. 41 and 42, "R" indicates reflectance, and "T" indicates transmittance. The subscript "p" in reflectance or transmittance indicates properties for the p-polarized part, and the subscript "s" for reflectance or transmittance indicates properties for the s-polarized part (this also applies to the other figures).

As is clear from FIGS. 41 and 42, the light reducing film 20 exhibits substantially 100% reflectance for the s-polarized portion of visible light incident at an incident angle of 40° or more. Also, the light reducing film 20 exhibits a transmittance of about 30% for visible light incident at an incident angle of 0°.

Therefore, the light-reducing film 20 reduces the light intensity attenuation of the optical path of the image transmission light flux L1 and only reduces the external light flux L2 in the visible spectrum by a reduction ratio of about 70%.

At this time, the brightness of the image (display image) viewed by the observing eye is maintained, while the brightness of the external image is reduced by about 30%. Therefore, when the external field of view is bright, the visibility of the displayed image is definitely enhanced. Therefore, selecting an appropriate type of film according to the incident angle according to the reflectance-transmittance characteristic of the light-reducing film 20 enables to obtain the desired effect with a minimum structure.

Although the basic structure of the light-reducing film 20 of this embodiment is a two-layer structure of a silver layer and a dielectric layer, other metal layers can also be used to replace the silver layer, or a three-layer structure in which two dielectric layers sandwich a metal layer can also be adopted. . However, the two-layer structure of the silver layer and the dielectric layer can relatively easily provide good characteristics (a characteristic of only reducing the attenuation of the external light flux L2 without increasing the attenuation of the image transmission light flux LI).

[First modified example of the eighth embodiment]

A first modified example of the eighth embodiment will be described below based on FIGS. 43 and 44 .

This modified example is a modified example of the light reducing film 20 .

The light reducing film 20 of this modified example is made of dielectric only. In this light reducing film 20, the thickness of each layer is set so that the phase of reflected light at the interface of each layer has a desired relationship, and various characteristics can be set according to the phase relationship of reflected light. Therefore, the degree of freedom in setting the transmittance is greater than that of the light reducing film 20 of the eighth embodiment. This dimming film 20 has the following three basic structures:

Flat substrate/(0.25H0.25L) ^P /air

planar substrate/(0.125H0.25L0.125H) ^P /air, and

Planar substrate/(0.125L0.25H0.125L) ^P /air, where

H: High refractive index dielectric (H layer)

L: Low refractive index dielectric (L layer)

Values to the left of each layer: the thickness of the optical layer of each layer (central wavelength of the wavelength range used), and

p: The number of stacked layers of the layer group enclosed by parentheses.

According to these basic structures, it is possible to reduce the transmittance to a certain light and to increase the reflectance to a certain light.

However, in order to securely reduce the brightness of external images, it is necessary to construct the light reduction film 20 to provide various cyclic layer groups with different center wavelengths in order to increase the wavelength range of light capable of reducing its transmittance up to the entire visible spectrum.

Furthermore, in order to reduce the variation of the transmittance depending on the color, it is necessary to optimize the layer thicknesses of all layers by computer.

The details (specifications) of the optimized light reduction film are as follows:

Set Transmittance: 5%

Central wavelength λ _C : 480 nm

Refractive index of planar substrate: 1.583

Refractive index of H layer: 2.3

Refractive index of layer L: 1.46, and

Total number of layers: 22.

The structure of the light reducing film 20 is shown in FIG. 43 .

N-BAF3 manufactured by SCHOTT was used as the planar substrate, and the same H and L layers as in the sixth embodiment were used for the H and L layers.

The wavelength characteristics of the transmittance of this light reducing film 20 are shown in FIG. 44 .

As shown in FIG. 44, the light reducing film 20 exhibits a transmittance of about 5% for visible light. Therefore, according to this modified example, the brightness of the external image is reduced to about 5%.

[Second modified example of the eighth embodiment]

A second modified example of the eighth embodiment is described below based on FIGS. 45 and 46 .

This modified example is a modified example of the light reducing film 20 .

The set transmittance of the light reducing film 20 of this modified example is 15%. This light-reducing film 20 is also made only of a dielectric, and its basic structure is the same as that of the first modified example.

The details (specifications) of the light reducing film 20 are as follows:

Set Transmittance: 15%

Central wavelength λ _C : 480 nm

Refractive index of planar substrate: 1.583

Refractive index of H layer: 2.3

Refractive index of layer L: 1.46, and

Total number of layers: 18.

The structure of the light reducing film 20 is shown in FIG. 45 . Also, the same material as the first modified example of this embodiment is used.

The wavelength characteristics of the transmittance of this light reducing film 20 are shown in FIG. 46 .

As clearly seen from FIG. 46, the light reducing film 20 exhibited a transmittance of 15% for visible light. Therefore, according to this modified example, the brightness of the external image is reduced to about 15%.

[Supplement to the modified example]

In view of the internal reflection condition of the planar substrate 11, the light-reducing film 20 of the first modified example and the second modified example is discussed under this condition to ensure the brightness of the displayed image, that is, under this condition, for the The image-transmitting light flux L1 reflected by the inner surface in the planar substrate achieves about 100% reflection.

First, assume a state where no light reduction film 20 is provided on the flat substrate 11, as shown in FIG. 47(a).

According to Snell's law, the following expression is proposed, wherein n ₀ is the refractive index of air in which the plane substrate 11 exists as a medium, n _g is the refractive index of glass as the material of the plane substrate, and θ ₀ , θ _g is the incident angle of light on the planar substrate 11 and the medium.

n ₀ sin θ ₀ = n _g sin θ _g

Therefore, the critical angle _θc (minimum value of the incident angle of light that is allowed to be reflected by the inner surface) of the planar substrate 11 in this state is expressed by the following expression:

θ _c = arc sin(n ₀ /n _g )

Next, assume a state where a light-reducing film 20 made of a multilayer dielectric film is provided on a flat substrate 11, as shown in FIG. 47(b). If each layer of the multilayer film has no absorption (zero absorption), the following expression is proposed according to Snell's law, where n ₁ , n ₂ ... n _k are the refractive indices of each layer of the multilayer film, and θ ₁ , θ ₂ ... θ _k are the incident angles of light on each layer.

n ₀ sinθ ₀ ＝n ₁ sinθ ₁

=n ₂ sinθ ₂

...

＝n _k sinθ _k

＝n _g sinθ _g

Therefore, if each layer of the multilayer film is not absorbing, the critical angle _θc of the planar substrate 11 is expressed by the same expression as in the state where the light reducing film 20 is not provided.

Therefore, a non-absorptive dielectric was used as the light reducing film 20 of the first example and the second example.

In addition, the angular characteristics of the reflectance on the side of the planar substrate 11 using the light-reducing films (reflectance of internal reflection of the planar substrate 11) of the first modified example and the second modified example of the non-absorbing dielectric are shown in FIG. 48 .

As shown in FIG. 48, the light reducing film 20 exhibits a reflectance of about 100% for light incident at an incident angle of 45° or greater.

[Third modified example of the eighth embodiment]

A third modified example of the eighth embodiment will be described below based on FIGS. 49 , 50 , 51 , 52 and 53 .

This modified example is a modified example of the light reducing film 20 .

The light reducing film 20 of this modified example has the function of preventing ultraviolet rays and infrared rays.

This light-reducing film is also made only of a dielectric, and its basic structure is the same as that of the first modified example and the second modified example.

In this modified example, an absorptive dielectric is indeed used as the H layer in order to provide UV and IR protection. Titanium dioxide (TiO ₂ ) was utilized as the absorptive dielectric.

Optical constants of titanium dioxide (TiO ₂ ) are shown in FIGS. 49 and 50 . FIG. 49 shows the wavelength characteristics of the refractive index of titanium dioxide (TiO ₂ ), and FIG. 50 shows the wavelength characteristics of the extinction coefficient of titanium dioxide (TiO ₂ ).

The details (specifications) of the light reducing film 20 are as follows:

Set Transmittance: 30%

Central wavelength λ _C : 800 nm

Refractive index of planar substrate: 1.583

Refractive index of layer L: 1.46, and

Total number of layers: 48.

The structure of the light reducing film 20 is shown in FIG. 51 . Also, the same materials as in the first modified example of this embodiment are used for the planar substrate and the L layer.

The wavelength characteristics of the transmittance of this light reducing film 20 are shown in FIG. 52 . The reflectance characteristic of the light reducing film 20 of this modified example on the flat substrate 11 side (the reflectance of the internal reflection of the flat substrate 11) is shown in FIG. 53 .

As shown in FIG. 53 , the curve of the wavelength characteristic of the reflectance has a zigzag shape (valley value of the reflectance).

On the other hand, the emission wavelength characteristic curve of the liquid crystal display element 21 of the glasses display generally has peaks in the respective wavelengths of red, green and blue.

Therefore, the structure of the light reducing film 20 of this modified example is finely adjusted so that the bottom of the curve of the wavelength characteristic of reflectance deviates from the peak of the emission wavelength characteristic.

As a result, each wavelength portion included in the image-transmitting light flux L2 is certainly reflected in the planar substrate 11 with a high reflectance inner surface. Therefore ensure the brightness of the displayed image.

Furthermore, as seen in Fig. 53, the valleys of the curves for the s-polarized part and the p-polarized part occur in different ways. Specifically, the valleys occurring in the curves of the p-polarization portion are relatively small.

Therefore, when the light-reducing film 20 is applied to a spectacle display, by limiting the image transmission luminous flux to the p-polarized part, it is possible to ensure that the valley of the reflectance wavelength characteristic curve deviates from the peak of the emission wavelength characteristic curve.

In addition, due to the principle of the liquid crystal display element, the image transmission luminous flux L1 is polarized, therefore, by optimizing the positional relationship between the liquid crystal display element 21 and the plane substrate 11, so that its polarization direction becomes p-polarized with respect to the light-reducing film direction, or by inserting a phase plate on a subsequent stage of the liquid crystal display element 21, it is possible to confine the image-transmitting light flux L1 to only the p-polarized portion.

[Ninth Embodiment]

A ninth embodiment of the present invention will be described below with reference to FIGS. 54 , 55 , 56 and 57 .

This embodiment is an embodiment of a glasses display. Here, only differences from the eighth embodiment are described.

Fig. 54 is an external view of such a glasses display. In FIG. 54 the coordinate system is a right-hand rule XYZ Cartesian coordinate system, where the X direction points down and the Y direction points to the right if viewed from an observer. In the following description, directions described with an XYZ coordinate system or directions expressed with up, down, left, and right as viewed from an observer will be used as necessary.

As shown in FIG. 54, this glasses display differs from the glasses display of the eighth embodiment in that the light reduction ratio of the central region near the half mirror 11b in the image display optical system 1 is set to be larger than that of the image display optical system 1. Peripheral area light reduction ratio outside the central area of system 1.

Moreover, in order to balance the light intensity of the external light flux guided from the external field of view to the observing eye (the observer's right eye) and the light intensity of the external light flux guided from the external field of view to the non-observing eye (the observer's left eye), in addition , in order to balance the left and right appearance of the glasses display, the front of the non-observation eye side has a light reduction function similar to that of the image display optical system 1, and a plane substrate 5, which has the same appearance as the image display optical system 1 .

55 is a detail of the optical system portion of the glasses display, and is a schematic sectional view of the optical system portion of the glasses display taken along a plane parallel to the YZ plane.

As shown in FIG. 55, the state of the image transmission luminous flux L1 and the external luminous flux L2 in this glasses display is the same as that of the eighth embodiment (see FIG. 38).

On the outer surface of the flat substrate 1b constituting the image display optical system 1, the same light reducing film 20 as that of the eighth embodiment or its modified example is provided.

However, the light-reducing film 40 made of multi-layer metal films or dielectric films overlaps on the central area of the surface of the light-reducing film 20 .

Therefore, the light reduction ratio in the central region of the image display optical system 1 is larger than that in the peripheral region of the image display optical system 1 .

In addition, the position of the central area seen from the observer and the position of the half mirror 11b seen from the observer are substantially the same. Also, the size of the central region seen from the observer is slightly larger than the size of the half mirror 11b seen from the observer.

In such a display for glasses as described above, the brightness of the external image of the background portion of the image display is particularly significantly reduced in order to further enhance the visibility of the displayed image.

Next, specific examples of the light reducing films 20, 40 will be described.

The light reducing film 20 is made of the same multilayer dielectric film as the modified example of the eighth embodiment. The light reducing film 40 is also made of the same multilayer dielectric film as the modified example of the eighth embodiment. The same planar substrate as that used in the modified example of the eighth embodiment was also used.

The details (specifications) of the light reducing film 20 are as follows:

Set transmittance of light-reducing film 20: 50%

Set transmittance of light-reducing film 40: 50%

Central wavelength λ _C : 800 nm

Refractive index of planar substrate: 1.583

Refractive index of H layer: 2.3

Refractive index of L layer: 1.46

Total number of layers of light reduction film 20: 11

Total layers of light reduction film 40: 16

The structures of light-reducing films 20 and 40 are shown in FIG. 56 .

The wavelength characteristics of the transmittance in the central region of the light reducing film 20, 40 and the wavelength characteristic of the transmittance in the peripheral region of the light reducing film 20 are shown in FIG. 57 .

As clearly shown in FIG. 57, the transmittance of the central region of visible light is about 25%, and the transmittance of the peripheral region of visible light is about 50%.

Therefore, according to this glasses display, the brightness of the entire external image image is reduced to about 50%, and the external image of the background portion of the displayed image is reduced to about 25%.

In this embodiment, the light reducing film 20 and the light reducing film 40 overlap each other, but they need not overlap each other. In this case, a light-reducing film 20 having an opening in a central region is provided on the planar substrate 11, and a light-reducing film 40 having a higher light-reducing ratio than the light-reducing film 20 is provided in the opening. However, in this case, a mask is required during the formation of the light-reducing film 20 and the formation of the light-reducing film 40 , therefore, in order to reduce manufacturing costs, it is more desirable that the light-reducing film 20 and the light-reducing film 40 overlap each other.

[First modified example of the ninth embodiment]

A first modified example of the ninth embodiment will be described below based on FIGS. 58 and 59 .

This modified example is a modified example of the light reducing film 20 and the light reducing film 40 .

The light reducing film 40 of this modified example is made of a metal thin film.

The structure of the light reducing film 20 of this modified example is the same as that shown in FIG. 45 . The light reducing film 20 has the same characteristics as those shown in FIG. 46 as a single element.

As for the structure of the light reducing film 40, it includes a chrome (Cr) layer of 5mm thick. Meanwhile, the central regions of the light-reducing films 20 and 40 have the wavelength characteristics of the transmittance shown in FIG. 58 .

Also, the angular characteristic (characteristic of the central region) of the reflectance (inner reflectance of the planar substrate 11) on the planar substrate 11 side of the light reducing film 20 is shown in FIG.

As shown in FIG. 59, the s-polarized partial reflectance has a high value for the above light incident at an incident angle of 40° or more. However, the reflectance for the p-polarized portion of this light is very low. Therefore, in the case where the light-reducing film 20, 40 of this modified example is applied to a display for glasses, the image-transmitting light flux L1 is limited to the s-polarized portion.

In addition, due to the principle of the liquid crystal display element 21, the image transmission light flux L1 is polarized, so by optimizing the positional relationship between the liquid crystal display element 21 and the planar substrate 11, its polarization direction becomes the s-polarization direction, or by Inserting a phase plate on the subsequent stage of the liquid crystal display element 21 can confine the image transmission light flux L1 to only the s-polarized portion.

[Second modified example of the ninth embodiment]

A second modified example of the ninth embodiment will be described below based on FIGS. 60 and 61 .

This modified example is a modified example of the light reducing film 20 . The light reducing film 20 of this modified example is made of a holographic optical film.

Two exposures occur in the manufacture of this holographic optical film.

The first exposure is exposure for making the holographic optical film characteristic of transmitting light incident at an incident angle of about 0°, with a predetermined transmittance. This exposure takes place in an optical system such as that shown in FIG. 60 .

Specifically, two light fluxes are vertically incident on the holographic photosensitive material 56 . An optical attenuator is inserted into one of the luminous fluxes. The transmittance value can be set by the attenuation amount of the optical attenuator 52 . In FIG. 60, 51 denotes a laser light source (capable of radiating laser beams with wavelengths of red, green and blue). BS represents a beam splitter, M represents a mirror, 53 represents a beam expander, and 55 represents a beam splitter.

The second exposure is exposure for securing the reflectance of the image-transmitting light flux L1 reflected on the inner surface in the planar substrate 11 . This exposure takes place in an optical system such as that shown in FIG. 61 .

Specifically, the two luminous fluxes are incident on the holographic photosensitive material 56 at the same angle as that of the image-transmitting luminous flux L1 reflected from the inner surface in the planar substrate 11 . In FIG. 61, 51 denotes a laser light source (capable of radiating laser beams with wavelengths of red, green and blue). BS represents a beam splitter, M represents a mirror, 53 represents a beam expander, and 57 represents a beam splitter.

After two exposures, the holographic photosensitive material 56 is developed to complete the holographic optical film.

In this way, the holographic optical film has the function that the light-reducing film 20 needs to have.

Although this modified example is a modified example of the light reducing film 20 made of a holographic optical film, the light reducing film 20 and the light reducing film 40 can be constituted by a holographic optical film.

In the manufacture of such holographic optical films, the first exposure is performed in two separate steps.

In one of the exposure steps, the central area of the holographic optical film is exposed (the peripheral area is masked), and in the other exposure step, the peripheral area is exposed (the central area is masked).

In these two exposure steps, the attenuation amount of the light attenuator 52 is set to different values. Therefore, the transmittance of the central region and the transmittance of the peripheral region of the holographic optical film are set to different values.

[Tenth Embodiment]

A tenth embodiment of the present invention will be described below with reference to FIGS. 62 , 63 , 64 , 65 and 66 .

This embodiment is an embodiment of a glasses display. Here, only the differences from the eighth embodiment will be described.

Fig. 62 is an external view of such a glasses display. The coordinate system of FIG. 62 is a right-hand-ruled XYZ Cartesian coordinate system, where the X direction points down and the Y direction points to the right if viewed from an observer. In the following description, directions represented by an XYZ coordinate system or directions represented by up, down, left, and right as seen from an observer will be used as necessary.

As shown in FIG. 62, the appearance of the glasses display is basically the same as that of the eighth embodiment (see FIG. 37).

FIG. 63 is a detailed view of such a display for glasses, and is a schematic cross-sectional view of the optical system portion of the display for glasses taken along a plane parallel to the YZ plane.

As shown in FIG. 63, the states of the image transmission luminous flux L1 and the external luminous flux L2 in the glasses display are the same as those of the eighth embodiment (see FIG. 38).

The first optical film 60 is provided on the outer side surface 1b of the planar substrate 11 . A second planar substrate 70 made of optical glass is provided on the surface of the first optical film 60 . A second optical film 80 is also pasted on the surface of the two-plane substrate 70 .

The first optical film 60 acts on the planar substrate 11 in the same way as the air gap. Specifically, the side interface of the planar substrate 11 of the first optical film 60 reflects the image transmission light flux L1 at a reflectance of substantially 100%. Also, the first optical film 60 transmits the external light flux L2. In addition, the first optical film may have a function of reducing visible light and a function of preventing ultraviolet or infrared.

The second planar substrate 70 and the second optical film 80 have the function of reducing the external light flux L2. In addition, the second planar substrate 70 and the second optical film 80 may have the function of reducing visible light and the function of preventing ultraviolet or infrared.

In this glasses display, the function of the first optical film 60 ensures the reflectance to the image transmission luminous flux L1 reflected by the inner surface in the planar substrate 11, so the second planar substrate 70 and the second optical film 80 have an enhanced effect on The reflectance of the image-transmitting luminous flux L1 is not essential.

Therefore, the degree of freedom in configuring the second planar substrate 70 and the second optical film 80 is large. For example any type of exit optical filter glass can be applied to the second planar substrate 70 .

Therefore, the second planar substrate 70 and the second optical film 80 can have a higher light-reducing function.

A high dimming function means, for example, that the dimming ratio varies little depending on the incident angle, the dimming ratio varies little depending on the wavelength, and the like.

Specific examples of the first optical film will be described below. Here, the case where the image transmission light flux is limited to the s-polarized portion will be described.

The structure of the first optical film 60 is as follows:

Planar substrate/(0.125L0.28H0.15L)(0.125L0.25H0.125L) ⁴ (0.15L0.28H0.125L)/second planar substrate, where

H: High refractive index dielectric (H layer)

L: Low refractive index dielectric (L layer)

Numerical values on the left side of each layer: layer thickness of each layer (central wavelength of the wavelength range used) and

Superscripted numbers: number of layer group overlaps in parentheses.

The details (specifications) of the first optical film 60 are as follows:

0169 central wavelength λ _C : 850 nm,

Refractive index of planar substrate: 1.56,

Refractive index of H layer: 2.30

Refractive index of L layer: 1.46

Refractive index of the second planar substrate: 1.507,

The extinction coefficient of the second planar substrate = 0.01.

In addition, the extinction coefficient of the second planar substrate 70 is set to a large value, such as 0.01, and the purpose is to use various types of optical filter glasses having a refractive index of 1.50 and a thickness of 1 mm as the second planar substrate 70, A second planar substrate 70 having various light reduction characteristics and wavelength cutoff functions is provided.

Fig. 64 shows the correction between calculated extinction coefficient k and transmittance for a glass substrate with a refractive index of 1.50 and a thickness of 1 mm.

It can be seen from Fig. 64 that the actual maximum value of the extinction coefficient k is 0.01.

Therefore, setting the extinction coefficient of the second planar substrate 70 to 0.01 makes it possible to construct an effective first optical film 60 regardless of which optical filter glasses are used as the second planar substrate 70 .

The wavelength characteristics (incident angle 0°, 60°) of the reflectance on the flat substrate 11 side of the first optical film are shown in FIG. 65 .

Furthermore, the angular characteristics of the reflectance of the first optical film 60 on the second flat substrate 70 side are shown in FIG. 66 .

As shown in FIG. 65 and shown clearly in FIG. 66, the first optical film 60 exhibits a reflectance of 10% or less for the s-polarized portion of visible light incident at an incident angle of 0°, and a reflectance of 10% or less for the s-polarized portion of visible light incident at an incident angle of 60°. The s-polarized portion of visible light incident at an angle of incidence exhibits essentially 100% reflectance.

Also, any filter glass can be used as the second planar substrate 70, as previously described. That is, any commercially available filter glass such as UV protectors, IR protectors, color filters, and neutral intensity filters (filters that attenuate light uniformly at all wavelengths in the visible spectrum) Both can be applied to the second planar substrate 70 .

Also, as the second optical film 80, any film suitable for protecting the surface of the second planar substrate 70, for example, an antireflection film or the like can be used. Preferably, a film that achieves desired properties when combined with the second planar substrate 70 is applied to the second optical film 80 .

For example, a neutral light intensity filter can be used as the second planar substrate 70 and an infrared protective film can be used as the second optical film 80 . Also, a UV protective glass can be used as the second planar substrate 70 , and a light reduction film and a UV protective film can be used as the second optical film 80 .

In short, the combination of the second planar substrate 70 and the second optical film 80 can be properly selected according to the required performance of the glasses display, the manufacturing cost of the glasses display, and the like.

In addition, the types and functions of various multilayer films such as various optical filters are described in detail in references, such as "Thin-Film optical Filters 3 ^rd Edition" by Macleod, and thus a detailed description thereof is hereby incorporated by reference. omit.

In the above-mentioned structure of the first optical film 60, the reason why a single-cycle layer group is arranged on both sides of the multi-cycle layer group is to adjust the refractive index mismatch between the first optical film 60 and the planar substrate 11. , and adjust the refractive index mismatch between the first optical film 60 and the second planar substrate 70 (ie, each single loop layer group is a matching layer). The matching layer is used to fine-tune the properties of the first optical film, for example, to reduce fluctuations in the wavelength range corresponding to the reduced transmittance.

[Modification example of the tenth embodiment]

The structure of the first optical film 60 may be different from that described above. Whichever structure is used, include the appropriate set of recurrent layers. Furthermore, no matter which structure is used, it is desirable to perform optimization using a computer.

Furthermore, when the second optical film 80 is combined with the second planar substrate 70, a combination of a metal thin film of chromium (Cr) etc. and an optical glass substrate having a small extinction coefficient can also be applied.

Moreover, as the second optical film 80, various functional optical films such as electrochromic film (EC film), photochromic film (PC film) and the like can be applied.

The electrochromic film (EC film) enables the user to choose whether to dim or not to dim according to the use state of the glasses display determined by the user's on operation. For example, the user can select, for example, to reduce the light when the external image is particularly bright during the day in the case of the glasses display being used outdoors, and to reduce the light when the external image is not very bright in the case of the glasses display being used indoors. When bright, no dimming.

Through this operation, the visibility of external images and the visibility of displayed images can be maintained regardless of the state of use of the glasses display.

Moreover, if a photochromic film is used, only when the light intensity of the external luminous flux L2 is high, the external luminous flux L2 can be automatically reduced, so that the visibility of the external image and the visibility of the displayed image can be automatically maintained, unlike the glasses display. Usage status is irrelevant.

Utilizing the above-mentioned functional film significantly improves the function of the glasses display.

Also, in this glasses display, like the ninth embodiment, the light reduction ratio of the central area of the image display optical system 1 can be easily set higher than that of the peripheral area of the image display optical system 1.

For example, the second planar substrate 70 is made of a neutral intensity filter, the second optical film 80 is made of a light-reducing film, and the formation area of the second optical film is limited to the central area.

In this glasses display, the first optical film 60 can be made of a holographic optical film. The optical system shown in Fig. 61 was used to manufacture holographic optical films. However, since the first optical film 60 is sandwiched between the planar substrate 11 and the second planar substrate 70 in use, auxiliary prisms of the same shape as these planar substrates are arranged in the light paths of the two luminous fluxes in FIG. 61 .

Also, in this glasses display, the second optical film 80 can be made of a holographic optical film.

【Other Embodiments】

The dimming function of the above-described eighth to tenth embodiments (including modified examples thereof) can be provided in any of the glasses displays of the first to seventh embodiments.

Industrial Applicability

In the above embodiments, only the glasses display has been described, but the present invention is equally applicable to viewfinders of cameras, binoculars, microscopes, telescopes, etc., and the like.

Claims (21)

1. optical element comprises:

Predetermined luminous flux can be by the planar substrates of its internal communication; With

The optical function unit, its the surperficial of described planar substrates of being arranged to can arrive with the predetermined luminous flux institute of described propagation closely contacts, and have interfere or or diffraction, described effect is reflected this predetermined luminous flux and transmission and is arrived this surperficial exterior light flux.

2. optical element as claimed in claim 1, wherein

Described optical function unit has the described predetermined luminous flux that is reflected in polarization on the concrete direction and the character of transmission luminous flux of polarization on other direction.

3. optical element as claimed in claim 1 or 2, wherein

Described optical function unit has the character that reaches the described predetermined luminous flux on described surface with desirable reflection characteristic reflection with the incident angle that is equal to or greater than critical angle, this critical angle is determined by the refractive index of described planar substrates and air, and this critical angle is that the luminous flux of this planar substrates inside is by the condition of total reflection.

4. as each described optical element in the claim 1 to 3, wherein

Described optical function unit has the function of the light intensity attenuation of the light path that reduces described exterior light flux and do not increase described predetermined luminous flux.

5. combiner optical systems comprises:

According to each described optical element in the claim 1 to 3, propagate this optical element from the image transmission luminous flux of predetermined picture display element emission, and this optical element is directed to the described exterior light flux of observing eyes in the transmission under the state of observing eyes of described planar substrates at least from outside visual field; With

Be arranged on the compositor in the described optical element, the described image transmission luminous flux that it has been propagated along the direction reflection of described observation eyes, and the described exterior light flux of transmission in described planar substrates.

6. combiner optical systems as claimed in claim 5, wherein

Described optical function unit is arranged on the lip-deep optical thin film of described planar substrates, and

Second planar substrates is arranged on the surface of described optical thin film.

7. combiner optical systems as claimed in claim 6, wherein

Described second planar substrates is to be used for the refractor that diopter is proofreaied and correct.

8. combiner optical systems as claimed in claim 6, wherein

Described optical function unit is arranged on the outer surface of described planar substrates, and

Whole optical system comprises described optical function unit, and described second planar substrates has the function of the light intensity attenuation of the light path that reduces described exterior light flux and do not increase described image transmission luminous flux.

9. combiner optical systems as claimed in claim 8, wherein

Described second planar substrates has the character that absorbs visible light.

10. combiner optical systems as claimed in claim 8, wherein

Described optical thin film has the function of the light intensity attenuation of the light path that reduces described exterior light flux and do not increase described image transmission luminous flux.

11. combiner optical systems as claimed in claim 8, wherein

Described optical thin film is made by metal and/or dielectric.

12. combiner optical systems as claimed in claim 8, wherein

Described optical thin film is made by the holographic optics film.

13. combiner optical systems as claimed in claim 8, wherein

Second optical thin film is arranged on the surface of described second planar substrates.

14. combiner optical systems as claimed in claim 13, wherein

Described second optical thin film is made by metal and/or dielectric.

15. combiner optical systems as claimed in claim 13, wherein

Described second optical thin film is made by the holographic optics film.

16. combiner optical systems as claimed in claim 13, wherein

Described second optical thin film is made by electrochomeric films.

17. combiner optical systems as claimed in claim 13, wherein

Described second optical thin film is made by photochromic film.

18. as any one described combiner optical systems in the claim 8 to 17, wherein

Whole optical system comprises described optical function unit, and described second planar substrates reduces the described exterior light flux be incident on the described compositor, and its minimizing ratio is higher than the ratio that remaining exterior light flux is reduced.

19., also comprise as any one described combiner optical systems in the claim 5 to 18

The guiding catoptron is used for the described image transmission luminous flux that sends from described image-displaying member along the direction guiding that described image transmission luminous flux is reflected by inside surface at described planar substrates.

20. an image-display units comprises:

Image-displaying member, be used to launch be used for image transmission luminous flux that image shows and

According to any one combiner optical systems in the claim 5 to 19, be used for described image transmission luminous flux is directed to described observation eyes.

21. image-display units as claimed in claim 20 also comprises

Installing component, described combiner optical systems is worn on observer's the head by this installing component.

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