Virtual image display device and optical unit

A virtual image display device includes an image light generation device generating image light, a transmissive tilted mirror reflecting the image light from the image light generation device, and a concave transmissive mirror reflecting, toward the transmissive tilted mirror, the image light reflected by the transmissive tilted mirror, and a light shielding film is provided on the external side of the concave transmissive mirror.

The present application is based on, and claims priority from JP Application Serial Number 2020-129071, filed Jul. 30, 2020, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a see-through type virtual image display device and an optical unit incorporated in the virtual image display device, and particularly to a virtual image display device and an optical unit of a type in which image light is reflected by a transmissive tilted mirror such that the light impinges on a concave transmissive mirror, and the reflection light from the concave transmissive mirror is observed through the transmissive tilted mirror.

2. Related Art

As a virtual image display device including a transmissive reflective surface and a concave mirror, a device including a prism member in which a transmissive reflective surface is incorporated is known, for example (see JP-A-2020-008749). It is disclosed that in this device, image light incident on the prism member is guided by totally reflecting it at a total reflection surface of the prism member toward the transmissive reflective surface, and the image light is reflected at the transmissive reflective surface toward the concave mirror disposed in front of the prism member.

In the virtual image display device disclosed in JP-A-2020-008749, the image light is emitted to the front side, and the image being displayed can be disadvantageously seen from the outside.

SUMMARY

A virtual image display device of an aspect of the present disclosure includes an image light generation device generating image light, a transmissive tilted mirror reflecting the image light from the image light generation device, and a concave transmissive mirror having a concave shape and reflecting, toward the transmissive tilted mirror, the image light reflected by the transmissive tilted mirror. The concave transmissive mirror includes a transmissive member, a reflection film, and a light shielding film. The transmissive member includes a first surface and a second surface opposing to the first surface. The reflection film on which the image light reflected by the transmissive tilted mirror is incident, the reflection film is provided along the first surface of the transmissive member. The light shielding film shields a part of the image light, the light shielding pattern film is provided along the second surface of the transmissive member.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

First Embodiment

With reference toFIGS.1to4and the like, a virtual image display device according to the present disclosure of the first embodiment and an optical unit incorporated in the virtual image display device are described below.

FIG.1is a drawing for describing a mounted state of a head-mounted display (hereinafter referred to also as an HMD)200, and with the HMD200, a viewer or a wearer US wearing it can recognize an image as a virtual image. InFIG.1and the like, X, Y, and Z are orthogonal coordinate systems, the +X direction corresponds to the lateral direction in which eyes EY of the viewer or the wearer US wearing the HMD200or a virtual image display device100are located, the +Y direction corresponds to an upward direction orthogonal to the lateral direction in which the eyes EY are located for the wearer US, and the +Z direction corresponds to a forward direction or a front direction for the wearer US. The ±Y direction is parallel to the vertical axis or the vertical direction.

The HMD200includes a right-eye first display device100A, a left-eye second display device100B, and a pair of temple-shaped support devices100C that supports the display devices100A and100B. The first display device100A is composed of a display driving part102disposed in the upper part, and an exterior member103with an eyeglass-lens shape that covers the front side of the eye. Likewise, the second display device100B is composed of the display driving part102disposed in the upper part and the exterior member103with an eyeglass-lens shape that covers the front side of the eye. The support device100C supports the upper end side of the exterior member103through the display driving part102. The first display device100A and the second display device100B are optically reversed left and right, and therefore the right-eye first display device100A is described as a representative of the virtual image display device100.

FIG.2is a perspective view for describing the virtual image display device100serving as the right-eye display device100A, andFIG.3is a drawing for describing an optical structure of the virtual image display device100. InFIG.3, a first region AR1is a side sectional view of an image light generation device11and an optical unit12, and a second region AR2is a plan view illustrating a partial cross section along light paths of the image light generation device11and the optical unit12.

As illustrated inFIG.2, the virtual image display device100includes the image light generation device11, the optical unit12and a display control circuit13. It should be noted that, in this specification, one in which the display control circuit13is omitted is also referred to as the virtual image display device100from the viewpoint of achieving the optical function. The image light generation device11and the display control circuit13are supported in the outer frame of the display driving part102illustrated inFIG.1, and a part of the optical unit12is also supported in the outer frame of the display driving part102.

The image light generation device11is a self-luminous display device, such as, for example, an organic EL (organic electroluminescence, Organic Electro-Luminescence) display, and forms a color still image or a moving image on a two-dimensional display surface11a.The image light generation device11performs a display operation by being driven by the display control circuit13. The image light generation device11is not limited to an organic EL display, and may be replaced with a display of an inorganic EL, an LED array, an organic LED, a laser array, a quantum dot light emission element and the like. The image light generation device11is not limited to a self-luminous image light generation device, and may be a device composed of a light modulation element such as an LCD and configured to form an image by illuminating the light modulation element using a light source such as a backlight. As the image light generation device11, a liquid crystal on silicon (LCOS (registered trademark)), a digital-micromirror-device and the like may be used in place of an LCD.

As illustrated inFIG.2andFIG.3, the optical unit12includes a projection optical system21, a transmissive tilted mirror23, and a concave transmissive mirror24. The term “transmissive mirror” of the concave transmissive mirror24means that it is a mirror that partially transmits light. The light path from the image light generation device11to the projection optical system21is disposed on the upper side of the transmissive tilted mirror23. To be more specific, the image light generation device11and the projection optical system21are disposed in a space sandwiched between a tilted plane extended from the transmissive tilted mirror23and a vertical plane extended upward from the upper end of the concave transmissive mirror24.

The projection optical system21projects image light ML emitted from the image light generation device11. The projection optical system21converges the image light ML emitted from the image light generation device11to form an image, and then injects it into the transmissive tilted mirror23. That is, the projection optical system21is disposed between the image light generation device11and the transmissive tilted mirror23on the light path. The projection optical system21includes a first lens system21a,a turning mirror21band a second lens system21c.The first lens system21aincludes two lenses,21fand21g,in the example illustrated inFIG.3, but may be composed of one lens or three or more lenses. The second lens system21cincludes one lens21iin the example illustrated inFIG.3, but may be two or more lenses. The lenses21f,21gand21imay be spherical lenses, non-spherical lenses, free curved surface lenses, and the like. The turning mirror21bis a plate-shaped optical member, and includes a flat reflective surface MS1. The flat reflective surface MS1of the turning mirror21bis composed of a metal film or a dielectric multilayer film. The flat reflective surface MS1is obtained by forming a reflective film composed of a single film or a multilayer film made of metal such as A1or Ag or other materials by vapor deposition and the like on a flat plate surface. The turning mirror21bbends an optical axis AX in a direction of an acute angle smaller than 90° in the YZ plane. The image light ML that travels through the first lens system21ain the +Z direction, which is the forward direction, is bent by the turning mirror21bin an oblique and rear downward direction between the −Y direction and the −Z direction, and then the light impinges on the transmissive tilted mirror23through the second lens system21c.

The transmissive tilted mirror23is an optical member in a form of a flat plate, and includes a flat reflective surface MS2having transmissivity. The transmissive tilted mirror23is a mirror in which a metal film or a dielectric multilayer film formed as a transmissive reflective film is formed on one surface23fof a parallel flat plate23ahaving a uniform thickness and transmissivity, and the transmissive reflective film functions as the flat reflective surface MS2. The reflectance and transmittance of the flat reflective surface MS2is set to approximately 50%, for example. It is to be noted that an anti-reflective film is formed on another surface23rof the parallel flat plate23a.The transmissive tilted mirror23bends the optical axis AX in a substantially orthogonal direction in the YZ plane. The image light ML that travels in a direction slightly tilted rearward with respect to the −Y direction, which is the downward direction, through the first lens system21aof the projection optical system21is bent by the transmissive tilted mirror23in a direction slightly tilted downward with respect to the +Z direction, which is the forward direction, such that the light impinges on the concave transmissive mirror24. The transmissive tilted mirror23is disposed between the concave transmissive mirror24and an exit pupil EP where the eye EY or the pupil hole is located, so as to cover the exit pupil EP. The transmissive tilted mirror23can be directly or indirectly fixed to the outer frame of the display driving part102illustrated inFIG.1such that the positional relationship with the concave transmissive mirror24and the like can be appropriately set.

With respect to the XY plane extending in the vertical direction as a reference, the transmissive tilted mirror23or the flat reflective surface MS2are tilted by an angle θ=approximately 20 to 40° in the counterclockwise direction around the X axis as viewed from the −X side (see the lateral sectional view ofFIG.3). As described above, the transmissive tilted mirror23is disposed such that the angle between the Y axis, which is a vertical axis, and the transmissive tilted mirror23is smaller than 45°. When the angle between the Y axis and the transmissive tilted mirror23is greater than 45°, the transmissive tilted mirror23is tilted than the standard (normal) state, and the thickness of the transmissive tilted mirror23in the Z-axis direction increases, whereas when the angle between the Y axis and the transmissive tilted mirror23is smaller than 45°, the transmissive tilted mirror23is raised than the standard (normal) state, and the thickness of the transmissive tilted mirror23in the Z-axis direction is reduced. That is, by setting the angle between the Y axis and the transmissive tilted mirror23to an angle smaller than 45° as in the present embodiment, an installation where the transmissive tilted mirror23largely protrudes in the −Z direction of the back surface with respect to the concave transmissive mirror24as a reference can be avoided, and the increase of the thickness of the virtual image display device100or the optical unit12in the Z direction in the front-rear direction can be avoided.

The concave transmissive mirror24is an optical member having a shape recessed to the exit pupil EP, and includes a transmissive reflective surface MC having transmissivity. The concave transmissive mirror24has a light convergence function, collimates the image light ML reflected and scattered at the transmissive tilted mirror23, and enters the light into the exit pupil EP through the transmissive tilted mirror23. The concave transmissive mirror24includes a surface recessed to the exit pupil EP and a convex surface toward the external side that is obtained by inverting a recessed surface, and thus has a uniform thickness while having a curved shape. The transmissive member24aof the concave transmissive mirror24is a base material that defines the external shape of the concave transmissive mirror24. The transmissive member24ahas a transmissivity for transmitting light without a substantial loss. On one surface24rof the transmissive member24a,a metal film or a dielectric multilayer film is formed as a transmissive reflective film, and such a transmissive reflective film functions as the concave transmissive reflective surface MC. The reflectance of the transmissive reflective surface MC is set to approximately 20 to 50%, for example. The transmissive reflective surface MC is not limited to a spherical surface, and may be an aspherical surface. The image light ML travelling forward after being reflected by the transmissive tilted mirror23is reflected back to the transmissive tilted mirror23by the concave transmissive mirror24such that the light is partially transmitted through the transmissive tilted mirror23and collected at the exit pupil EP. An emission light axis AXE from the transmissive tilted mirror23toward the concave transmissive mirror24coincides with the optical axis AX folded back at the concave transmissive mirror24toward the exit pupil EP. The image light ML impinges on the entirety of the transmissive reflective surface MC of the concave transmissive mirror24from an almost perpendicular direction, and thus has a high optical symmetry. The concave transmissive mirror24covers the transmissive tilted mirror23on the external side. The transmissive tilted mirror23is disposed between the concave transmissive mirror24and an exit pupil EP where the eye EY or the pupil hole is located, so as to cover the exit pupil EP. In the optical system illustrated in the drawing, the emission light axis AXE, which is an axis line from the transmissive tilted mirror23toward the concave transmissive mirror24and is also an axis line from the concave mirror24toward the center of the exit pupil EP, extends with a downward tilt of approximately 10° with respect to the +Z direction as the forward direction. With the emission light axis AXE tilted downward on the front side at approximately 10° with respect to the Z axis, which is a horizontal axis, the fatigue of the eye EY of the wearer US observing virtual images can be reduced.

The concave transmissive mirror24is incorporated to constitute a part of the transmissive exterior member103illustrated inFIG.1. That is, by providing a transmissive or non-transmissive plate-shaped member in an extended manner around the concave transmissive mirror24, the exterior member103including the concave transmissive mirror24can be achieved. The exterior member103is not limited to the eyeglass-lens form, and may have various outlines or exterior appearances.

Regarding the light paths, the image light ML from the image light generation device11is focused and bent by the projection optical system21to form an image, and then impinges on the transmissive tilted mirror23. The image light ML that is reflected by, for example, approximately 50% at the transmissive tilted mirror23impinges on the concave transmissive mirror24so as to be reflected at the transmissive reflective surface MC at a reflectance of approximately 50% or less, for example. The image light ML reflected at the concave transmissive mirror24passes through the transmissive tilted mirror23and impinges on the exit pupil EP where the eye EY or the pupil hole of the wearer US is located. Here, the exit pupil EP is an eye point of the optical unit12where the eye EY is assumed to be disposed, and light from each point of the display surface11aof the image light generation device11impinges in a collected manner in one place at an angle that allows observation of virtual images. An intermediate image II is formed between the transmissive tilted mirror23and the projection optical system21. The intermediate image II is an image obtained by appropriately enlarging an image formed on the display surface11aof the image light generation device11. External light OL transmitted through the concave transmissive mirror24also impinges on the exit pupil EP. That is, the wearer US wearing the HMD200can observe a virtual image of the image light ML superimposed on external images.

It is to be noted that while the concave transmissive mirror24transmits the external light OL, it also transmits the image light ML, and thus generates leaked light LE on the front side of the concave transmissive mirror24. If the intensity of the leaked light LE is high, a third party OS existing around the wearer US can observe a part PI of the image displayed on the display surface11aof the image light generation device11(seeFIG.1). In contrast, in the present embodiment, as described later, a light shielding pattern film41(seeFIG.4) is provided on the external side of a transmissive reflective film24bin the concave transmissive mirror24to suppress the leaked light LE, and thus the situation where the part PI of the image can be observed by the third party OS is avoided.

A structure of the concave transmissive mirror24is described below with reference toFIG.4. The concave transmissive mirror24includes the transmissive member24athat is a supporting body61for maintaining the entire shape, the transmissive reflective film24bformed on the inner side (the exit pupil EP side inFIG.3) of the transmissive member24a,the light shielding pattern filml41formed on the external side of the transmissive member24a,and the anti-reflection film24cformed on the external side of the light shielding pattern film41. It is to be noted that the anti-reflection film24cmay be omitted.

From the viewpoint of ensuring the strength of the shape, the concave transmissive mirror24or the transmissive member24ahas a thickness of 1 mm or greater, but preferably has a thickness of 2 mm or smaller from the viewpoint of weight reduction. The transmissive member24ais formed of an optically transparent resin such as acrylic resin and polycarbonate resin, and transmits the image light ML without attenuation. The transmissive member24ais formed by injection molding, for example.

The transmissive reflective film24bfunctions as the transmissive reflective surface MC, and reflects the image light ML at a desired reflectance. The transmissive reflective film24bhas a structure in which a metal film is covered with a protective film, and can be formed by depositing metal or metal oxide of aluminum, silver and the like on a first surface2aof the transmissive member24aon the exit pupil EP side. At this time, the reflectance of the transmissive reflective film24bcan be adjusted through adjustment of the thickness of the metal film the like. The transmissive reflective film24bis not limited to the metal film, and may be formed of a dielectric multilayer film. To be more specific, several types of metal oxide films are stacked in the film thickness based on the optical design, on the first surface2aof the transmissive member24a.In this manner, the reflectance of the transmissive reflective film24bcan be substantially equalized in the wavelength range of each color included in the image light ML, and thus the transmissive reflective film24bcan reflect the image light ML at a desired reflectance over the entire wavelength range. It is to be noted that it is not necessary to form the transmissive reflective film24bdirectly on the transmissive member24a.For example, the transmissive member24amay be covered with a hard coat film and the transmissive reflective film24bmay be formed on top of that.

The light shielding pattern film41is configured to perform partial light shielding, and is provided in an emission side surface, which is the external side of the transmissive reflective surface MC formed in the concave transmissive mirror24, or more specifically, in a second surface2bof the transmissive member24a.Here, the light shielding pattern film41includes one discretely formed in the emission side surface of the concave transmissive mirror24. The light shielding pattern film41suppresses emission, to the external side, of emission light passed through the transmissive reflective film24b.That is, the light shielding pattern film41formed on the emission side surface of the concave transmissive mirror reduces the image light transmitted through the transmissive reflective surface MC.

FIG.5is an enlarged front view illustrating a structure of the light shielding pattern film41. The light shielding pattern film41includes a light reduction region42and a transmissive region43. With the light reduction region42of the light shielding pattern film41, the image light ML transmitted through the transmissive reflective surface MC can be reduced. The transmissive region43can transmit substantially 100% of the incident light. The light reduction region42is a region in which a plurality of pattern elements44is arranged on two-dimensionally grid points.FIG.5illustrates a part of the light shielding pattern film41, and the pattern elements44are arranged in the entirety of the light shielding pattern film41. The pattern element44has one of a full absorption function and a partial absorption function. Here, the full absorption includes a case including several % of transmission, reflection, scattering or the like. Each of the pattern elements44that constitutes the light shielding pattern film41absorbs the image light ML at a desired absorptivity. In this manner, the absorptivity at the light shielding pattern film41can be adjusted by the installation, shape, pitch, area occupancy in the entirety of the transmissive reflective surface MC and the like of the pattern element44. Regarding the entirety of the light shielding pattern film41, it is possible to achieve the desired light reduction, such as reduction of the transmittance to 1/2 by setting the absorptivity to 1/2, for example.

The pattern element44has a circular shape, a triangular shape, polygonal shape, a star shape or the like, for example. In the example illustrated inFIG.5, the pattern element44has a circular shape. In the circular pattern corresponding to the pattern element44, the center of the circular shape is arranged on the grid point. The pattern element44is arranged in a density that does not cause diffraction. The pattern element44can be arranged with regularity, as in the illustrated example, but it is more desirable to be randomly arranged with no regularity.

The size of the pattern element44is approximately hundreds of micrometers to 3 mm, preferably approximately hundreds of micrometers to 2 mm. The pattern element44has a pitch of 100 μm to 2 mm such that diffraction is not caused in the light shielding pattern film41. The thickness of the pattern element44is 100 μm or smaller, for example. It is to be noted that a thickness of approximately 100 μm is required in the case where the pattern element44is of the full absorption type, but the thickness may be smaller than 100 μm in the case where the pattern element44is of the partial absorption type with a transmittance of 50%, for example.

The light shielding pattern film41can be formed by patterning a metal thin film on the external side surface of the resin that constitutes the transmissive member24aillustrated inFIG.4, i.e., on the second surface2b,for example. The metal thin film is formed as a multilayer film by vapor deposition, sputtering and the like using materials such as metals such as Ag, Cr and Al and dielectric materials, for example. The patterning may be performed by etching, mask vapor deposition, or liftoff. In addition, the light shielding pattern film41may be pattern-formed by applying an absorber such as a carbon. In addition, the light shielding pattern film41may be formed by pasting a resin film of polyester, polycarbonate or the like colored in a black or grey pattern.

The resin film has the advantage of being resistant to scattering when the concave transmissive mirror24is broken. It is to be noted that the pattern element44may be formed by printing and/or ink-jet printing.

The anti-reflection film24cprevents the image light ML passed through the transmissive reflective film24band the light shielding pattern fil41from traveling backward and forming ghosts. The anti-reflective film24cis a dielectric multilayer film. The anti-reflection film24cis formed by stacking several types of metal oxide films in a film thickness in accordance with the optical design on an external surface41aof the light shielding pattern fil41. It is to be noted that the anti-reflection film24cmay not be directly formed on the light shielding pattern filml41. For example, the light shielding pattern film41may be covered with a hard coat film, and the anti-reflection film24cmay be formed on top of that. When the hard coat film is provided, the hard coat film constitutes the transmissive region43except for the light reduction region42or the pattern element44in the light shielding pattern film41.

Assuming that the reflectance of the transmissive reflective film24bis α and the transmittance of the entirety or average of the light shielding pattern film41is γ, the image light ML is attenuated to (1−α) from the original state via the transmissive reflective film24b,and attenuated to (1−α)·γ on average from the original state by being passed through the light shielding pattern fil41. In the case where the reflectance α and the transmittance γ are 1/2, for example, the intensity of the image light ML emitted to the external side of the concave transmissive mirror24is attenuated to 1/4. It is to be noted that the external light OL is attenuated to γ·(1−α) on average by the concave transmissive mirror24. In the case where the reflectance α and the transmittance γ are 1/2, for example, the intensity of the external light OL that reaches the transmissive tilted mirror23through the concave transmissive mirror24is attenuated to 1/4. From the above, with the concave transmissive mirror24used in the present embodiment, it is easier to prevent other persons from observing the image light ML while ensuring the see-through property, and the privacy can be improved.

With reference toFIG.6, a first to third modifications of the concave transmissive mirror24illustrated inFIG.5are described below. InFIG.6, a first region BR1is an enlarged front view of the light shielding pattern fil41of the first modification, a second region BR2is an enlarged front view of the light shielding pattern film41of the second modification, and a third region BR3is an enlarged front view of the light shielding pattern film41of a third modification.

In the case of the first modification illustrated in the first region BR1ofFIG.6, the triangular pattern corresponding to the pattern element44that constitutes the light shielding pattern film41is arranged such that the gravity center of the triangle is arranged on the grid point and the area of the triangular shape gradually decreases from the center of the concave transmissive mirror24in the up/down direction, i.e., the Y direction or the vertical direction ofFIG.2.

In the case of the second modification illustrated in the second region BR2ofFIG.6, the circular pattern corresponding to the pattern element44that constitutes the light shielding pattern film41is denser than the pattern illustrated inFIG.5. In addition, the light shielding pattern fil41includes the pattern elements44having different absorptivities. In the example illustrated in the drawing, in the light shielding pattern fil41, lines of the pattern elements44awith an absorptivity of 100% and lines of the pattern elements44bwith an absorptivity of 50% are alternately arranged, for example. It is to be noted that in the light shielding pattern fil41, by increasing the area occupied by the pattern elements44aand44b,light emitted to the outside is reduced, and the privacy can be improved.

In the case of the third modification illustrated in the third region BR3ofFIG.6, the star pattern corresponding to the pattern element44that constitutes the light shielding pattern film41is arranged such that the center of gravity of the star shape is arranged on the grid point.

With reference toFIG.7, a fourth modification of the concave transmissive mirror24illustrated inFIG.4is described below. The concave transmissive mirror124illustrated inFIG.7includes the transmissive member124athat is the supporting body61, the transmissive reflective film24bformed on the inner side of the transmissive member124a,the light shielding pattern film41formed on the external side of the transmissive member124a,and the anti-reflection film24cformed on the external side of the light shielding pattern film41.

The transmissive member124ais an emission light absorption member45, and suppresses emission, to the external side, of emission light passed through the transmissive reflective film24b.With the transmissive member124a,i.e., the emission light absorption member45, desired light reduction, such as reduction of the transmittance to, for example, 1/2, can be achieved, and further light reduction of the transmittance to 1/2 can be achieved with the light shielding pattern film41. The emission light absorption member45is composed of a material in which an absorber is dispersed in a base material of resin. More specifically, the emission light absorption member45is formed by adding nano particles of metal or the like with a size of approximately 10 to 100 nm to the resin. Here, when the nano particles dispersed in the emission light absorption member45are particles that absorb light with a good balance among three colors of RGB, light reduction maintaining the color tone of the transmitted light can be achieved. The transmittance of the emission light absorption member45can be adjusted through adjustment of the density of nano particles in the emission light absorption member45and the like. The metal nano particles are not limited to a single metal, and may be also be an alloy or the like. The emission light absorption member45is not limited to one in which nano particles are dispersed in a base material of resin, and it is possible to use one in which inorganic pigment and/or organic pigment is mixed in resin may be used. In this case, the color mixing can be achieved through selection and/or blending of the pigment. Further, resins with carbon fiber kneaded into them can also be used.

In the virtual image display device100of the first embodiment described above, the light shielding pattern fil41that performs partial light shielding is provided on the external side of the transmissive reflective surface MC formed in the concave transmissive mirror24, and therefore the image light transmitted through the transmissive reflective surface MC and emitted to the external side is reduced by the light shielding pattern film41, and, the image being displayed is less seen from the outside, thus increasing of the effect of suppressing information leakage. It is to be noted that through the use of the transmissive tilted mirror23, the weight of the optical system of the virtual image display device can be reduced in comparison with a case where a prism member is used.

It is to be noted that the light reduction region42in the light shielding pattern film41may include one of a pattern element of a total reflection and a pattern element of a partial reflection. Here, the total reflection includes transmission, absorption, scattering and the like of several %. Each of the pattern elements44that constitutes the light shielding pattern fil41reflects the image light ML at a desired reflectance. In this manner, the reflectance at the light shielding pattern film41can be adjusted by the installation, shape, pitch, area occupancy in the entirety the transmissive reflective surface MC and the like of the pattern element44. In the case where the light reduction region42includes the reflective pattern element44, it is necessary to prevent generation of ghost, and the generation of ghost can be suppressed through absorption and/or interference by disposing a filter composed of a combination of a dielectric and a metal film on the inner side of the light shielding pattern film41, for example. This filter may replace the emission light absorption member45illustrated inFIG.7. In addition, the light reduction region42may be a combination of absorption pattern elements and reflective pattern elements.

In addition, although not illustrated in the drawing, the light shielding pattern film41may be formed in such a manner that it is embedded inside the transmissive member24a,or may be formed between the transmissive reflective film24band the transmissive member24a.

Second Embodiment

A virtual image display device of a second embodiment is described below. The virtual image display device and the like of the second embodiment are obtained by partially changing the virtual image display device of the first embodiment, and therefore the description for the common portions is omitted.

With reference toFIG.8, an optical unit212incorporated in the virtual image display device of the second embodiment is described below.

InFIG.8, a first region CR1is an enlarged sectional view illustrating a region around the concave transmissive mirror224in the optical unit212. A shade51is disposed on the external side of the concave transmissive mirror224. The shade51is detachably fixed to the display driving part102illustrated inFIG.1and disposed to face the concave transmissive mirror224with a space therebetween. The concave transmissive mirror224does not include the light shielding pattern film41on the external side in the structure described in the first embodiment. The anti-reflection film24cis formed in the second surface2b,which is the emission side surface of the concave transmissive mirror224. The shade51includes the transmissive member51athat is a supporting body62, the anti-reflection film51bformed on the inner side of the transmissive member51a,a light shielding pattern film541formed on the external side of the transmissive member51a,and an anti-reflection film51dformed on the external side of the light shielding pattern film541. The light shielding pattern film541has the same structure as that illustrated inFIG.5andFIG.6. The light shielding pattern film541reduces the incident intensity of external light on the concave transmissive mirror224. In addition, the light shielding pattern film541suppresses emission, to the external side, of the image light ML passed through the concave transmissive mirror224. That is, the image light ML passed through the concave transmissive mirror224is attenuated by the light shielding pattern film541formed in the shade51, and thus the image being displayed can be made less seen from the outside. In addition, by providing the light shielding pattern film41in the shade51, it is possible to achieve a good see-through property when the shade51is not used, and the improved privacy when the shade51is used.

InFIG.8, a second region CR2is an enlarged sectional view illustrating the optical unit212of a modification. In the example illustrated in the drawing, in place of the transmissive member24aillustrated in the first region CR1, the entirety of the transmissive member224athat is the supporting body61is the emission light absorption member45composed of a material in which an absorber is dispersed in the base material of resin. As in the first region CR1, the shade51includes the transmissive member51athat is the supporting body62, the anti-reflection film51bformed on the inner side of the transmissive member51a,the light shielding pattern film541formed on the external side of the transmissive member51a,and the anti-reflection film51dformed on the external side of the light shielding pattern film541.

It is to be noted that in the optical unit212in the first and second regions CR1and CR2, the light shielding pattern film may be provided also in the emission side surface of the concave transmissive mirror224, for example.

As illustrated inFIG.9, the shade51is detachably fixed to the eyeglass-frame shaped portion provided in the display driving part102. The shade51covers the entirety of exterior member103including the concave transmissive mirror224. As a result, the shade51is provided in a region that covers the transmissive members24aand224aor the transmissive reflective film24bformed on the inner side of the concave transmissive mirror224. In the case where the transmissive reflective film24bis provided in the concave transmissive mirror224, the shade51is provided in a region that covers the transmissive reflective film24b.In this manner, with the shade51that completely covers the transmissive reflective film24b,the image light ML is less seen from the outside. It is to be noted that in the case where the transmissive reflective film24bis not formed in the entire region of the concave transmissive mirror224, the shade51may be configured to cover a narrow region that faces the transmissive reflective film24b.

Third Embodiment

A virtual image display device of a third embodiment is described below. The virtual image display device and the like of the third embodiment are obtained by partially changing the virtual image display device of the first embodiment, and therefore the description for the common portions is omitted.

With reference toFIG.10andFIG.11, the virtual image display device of the third embodiment is described below.FIG.10is a schematic perspective view illustrating a structure of the virtual image display device100. InFIG.11, a first region DR1is a side view of the image light generation device11and an optical unit312, and a second region DR2is a plan view illustrating a partial cross section along light paths of the image light generation device11and the optical unit312.

The optical unit312includes the transmissive tilted mirror23and the concave transmissive mirror24. That is, in the virtual image display device of the third embodiment, the image light ML is caused to impinge on the concave transmissive mirror24without forming an intermediate image.

Regarding the light paths, the image light ML from the image light generation device11impinges on the transmissive tilted mirror23. The image light ML that is reflected by, for example, approximately 50% at the transmissive tilted mirror23impinges on the concave transmissive mirror24so as to be reflected at the transmissive reflective surface MC at a reflectance of approximately 50% or less, for example. The image light ML reflected by the concave transmissive mirror24impinges on the exit pupil EP where the eye EY or the pupil hole of the wearer US is located. External light OL transmitted through the concave transmissive mirror24also impinges on the exit pupil EP. That is, the wearer US wearing the HMD200can observe a virtual image of the image light ML superimposed on external images.

In the optical unit312, the concave transmissive mirror24has the same structure as that illustrated inFIGS.4to7. In addition, the shade51illustrated inFIG.8can be detachably disposed on the external side of the concave transmissive mirror24.

Fourth Embodiment

A virtual image display device of a fourth embodiment is described below. The virtual image display device and the like of the fourth embodiment are obtained by partially changing the virtual image display device of the first embodiment, and therefore the description for the common portions is omitted.

With reference toFIG.12, the virtual image display device of the fourth embodiment is described below. An optical unit412includes a projection optical system421, a turning mirror22, the transmissive tilted mirror23, and the concave transmissive mirror24. Specifically, the turning mirror22is disposed between the projection optical system421and the transmissive tilted mirror23.

The turning mirror22includes a first mirror22aand a second mirror22bin the order of the light path from the image light generation device11. The turning mirror22reflects, in the intersection direction, the image light ML from the projection optical system421. On the light emission side of the second mirror22b,the transmissive tilted mirror23is disposed. A projection optical axis AX0, which is an optical axis of the projection optical system421, extends in parallel with the X-axis direction of the lateral direction. The light path is bent by the first mirror22aalong the reflection optical axis AX1from the projection optical axis AX0, and the light path is bent by the second mirror22balong the reflection optical axis AX2from the reflection optical axis AX1. As a result, the optical axis extended in an approximately horizontal direction on the emission side of the projection optical system421extends in an almost vertical direction on the incident side of the transmissive tilted mirror23.

With respect to the XY plane extending in the vertical direction as a reference, the transmissive tilted mirror23is tilted at an angle θ=approximately 20 to 40° in the counterclockwise direction around the X axis as viewed from the −X side. The light path from the image light generation device11to the turning mirror22is disposed on the upper side of the transmissive tilted mirror23. To be more specific, the image light generation device11, the projection optical system421, and the turning mirror22are disposed in a space sandwiched between a tilted plane extended from the transmissive tilted mirror23and a vertical plane extended upward from the upper end of the concave transmissive mirror24.

In the optical unit412, the concave transmissive mirror24has the same structure as that illustrated inFIGS.4to7. In addition, the shade51illustrated inFIG.8can be detachably disposed on the external side of the concave transmissive mirror24.

Fifth Embodiment

A virtual image display device of a fifth embodiment is described below. The virtual image display device and the like of the fifth embodiment are obtained by partially changing the virtual image display device of the first embodiment, and therefore the description for the common portions is omitted.

With reference toFIG.13, the virtual image display device of the fifth embodiment is described below. In the present embodiment, the transmissive reflective surface MC is formed in the region A1that faces the transmissive tilted mirror23in the concave transmissive mirror24, and the light shielding pattern film41is formed in a substantially rectangular shape so as to cover the transmissive reflective surface MC in the direction of the emission light axis AXE on the external side of the transmissive reflective surface MC. In the regions A2and A3around the region A1, a reflectance transition region whose reflectance gradually decreases with respect to the transmissive reflective surface MC may be formed, or an absorptivity transition region or a reflectance transition region whose absorptivity or reflectance gradually decreases with respect to the light shielding pattern film41may be formed.

In the present embodiment, the concave transmissive mirror24has the same structure as that illustrated inFIGS.4to7. In addition, the shade51illustrated inFIG.8can be detachably disposed on the external side of the concave transmissive mirror24.

Modification and So Forth

The present disclosure is described according to the above-mentioned exemplary embodiments, but the present disclosure is not limited to the above-mentioned exemplary embodiments. The present disclosure may be carried out in various modes without departing from the gist of the present disclosure, and, for example, the following modifications may be carried out.

While the virtual image display device100of the above-mentioned embodiments uses self-luminous display devices such as organic EL elements and other light modulation elements such as LCDs as the image light generation device11, it is also possible to adopt a configuration using a laser scanner including a combination of a laser light source and a scanner such as a polygon mirror, in place of the above-mentioned configuration. Specifically, the present disclosure is applicable to a head-mounted display of a laser retinal projection type.

The transmissive member24athat constitutes the concave transmissive mirror24is not limited to a resin material, and may be formed of glass and/or synthetic quartz.

The optical unit12may be an optical system including a light guide, a prism, a complex of a prism and a mirror, and the like in the preceding stage of the transmissive tilted mirror23.

The concave transmissive mirror24may be provided with, in place of the transmissive reflective film24b,a partial reflective whose reflectance is increased in a plurality of wavelength bands with a function of a band reflection filter or a function of a notch filter.

A virtual image display device of a specific aspect includes an image light generation device, a transmissive tilted mirror configured to reflect image light from the image light generation device, and a concave transmissive mirror configured to reflect, toward the transmissive tilted mirror, the image light reflected by the transmissive tilted mirror. A light shielding pattern film configured to perform partial light shielding is provided on an external side of a transmissive reflective surface formed in the concave transmissive mirror. Here, the light shielding pattern film includes one discretely formed in the surface of the concave transmissive mirror.

Since the above-mentioned virtual image display device includes a light shielding pattern film configured to perform partial light shielding on the external side of the transmissive reflective surface formed in the concave transmissive mirror, the image light transmitted through the transmissive reflective surface and emitted to the external side is reduced by the light shielding pattern film, and the image being displayed is less seen from the outside, thus increasing of the effect of suppressing information leakage. It is to be noted that through the use of the transmissive tilted mirror, the weight of the optical system of the virtual image display device can be reduced in comparison with a case where a prism member is used.

In a specific aspect, the light shielding pattern film is formed in an emission side surface of the concave transmissive mirror. With the light shielding pattern film formed on the emission side surface of the concave transmissive mirror, the image light transmitted through the transmissive reflective surface is reduced.

In another specific aspect, the light shielding pattern film includes a light reduction region and a transmissive region. In this case, the image light transmitted through the transmissive reflective surface can be reduced using the light reduction region.

In a still another specific aspect, the light reduction region is a region in which a plurality of pattern elements having a pitch of 100 μm or greater is two-dimensionally arranged. In this case, generation of diffraction at the light shielding pattern film can be suppressed.

In a still another specific aspect, the light reduction region includes one of a pattern element of a full absorption and a pattern element of a partial absorption. In this case, the absorptivity at the light shielding pattern film can be adjusted by the installation, shape, pitch, area occupancy in the entirety of the transmissive reflective surface and the like of the pattern element.

In a still another specific aspect, the light reduction region includes one of a pattern element of a total reflection and a pattern element of a partial reflection. In this case, the reflectance at the light shielding pattern film can be adjusted by the installation, shape, pitch, area occupancy in the entirety of the transmissive reflective surface and the like of the pattern element.

In a still another specific aspect, the transmissive reflective surface is formed in a region that faces the transmissive tilted mirror in the concave transmissive mirror, and the light shielding pattern film is formed in a substantially rectangular shape covering the transmissive reflective surface in a direction of an emission light axis, on the external side of the transmissive reflective surface.

In a still another specific aspect, an anti-reflection film is formed to cover the light shielding pattern film.

In still another specific aspect, the concave transmissive mirror reflects the image light toward the transmissive tilted mirror to form an exit pupil.

In still another specific aspect, the virtual image display device further includes a shade spaced apart from the concave transmissive mirror on the external side of the concave transmissive mirror. In this case, with the shade, the image light emitted to the outside of the virtual image display device can be reduced, and the effect of preventing information leakage can be further increased.

In a still another specific aspect, the shade includes the light shielding pattern film. The shade may perform light shielding using a mirror having transmissivity, but may perform light shielding using the above-mentioned light shielding pattern film.

In a still another specific aspect, the shade is provided in a region that covers the transmissive reflective surface provided on an inner side of the concave transmissive mirror.

In a still another specific aspect, the transmissive reflective surface is formed in a region that faces the transmissive tilted mirror in the concave transmissive mirror, and the light shielding pattern film is formed in a substantially rectangular shape covering the transmissive reflective surface in a direction of an emission light axis, on the external side of the transmissive reflective surface.

In still another specific aspect, an emission light axis extending from the transmissive tilted mirror toward the concave transmissive mirror is set to a forward and downward direction with respect to a horizontal axis.

In still another specific aspect, the virtual image display device further includes a turning mirror configured to reflect, in an intersection direction, the image light from the image light generation device. In this case, it is possible to easily prevent the image light generation device and associated optical elements from largely protruding upward and rearward of the transmissive tilted mirror, and the virtual image display device can be downsized, thus achieving a slender exterior appearance.

In still another specific aspect, the virtual image display device further includes a projection optical system disposed between the image light generation device and the transmissive tilted mirror and configured to form an intermediate image. In this case, the image quality can be increased while downsizing the image light generation device with the projection optical system.

In still another specific aspect, the image light impinges on the concave transmissive mirror without forming an intermediate image.

An optical unit of a specific aspect includes a transmissive tilted mirror configured to reflect image light, and a concave transmissive mirror configured to reflect, toward the transmissive tilted mirror, the image light reflected by the transmissive tilted mirror. A light shielding pattern film configured to perform partial light shielding is provided on an external side of a transmissive reflective surface formed in the concave transmissive mirror.

Since the above-mentioned optical unit includes a light shielding pattern film configured to perform partial light shielding on the external side of the transmissive reflective surface formed in the concave transmissive mirror, the image light transmitted through the transmissive reflective surface and emitted to the external side is reduced by the light shielding pattern film, and the image being displayed is less seen from the outside, thus increasing of the effect of suppressing information leakage. It is to be noted that through the use of the transmissive tilted mirror, the weight of the optical system of the optical unit can be reduced in comparison with a case where a prism member is used.