JP2022150353A - Virtual image display device and pupil expansion element - Google Patents

Abstract

To expand an exit pupil while preventing the occurrence of color unevenness.SOLUTION: A virtual image display device 100 comprises an image forming device 101 and a pupil expansion element 50. The pupil expansion element 50 has a plurality of first transmissive mirrors M1 and a plurality of second transmissive mirrors M2. The first transmissive mirrors M1 are inclined toward an emission surface 52 with respect to a first direction D1 in which the pupil expansion element 50 extends, and the second transmissive mirrors M2 are inclined toward the emission surface 52 with respect to a second direction D2 being the opposite direction to the first direction D1 in which the pupil expansion element 50 extends. The pupil expansion element 50 has a first area R1 where the first transmissive mirror M1 and the second transmissive mirror M2 are arranged side by side along the second direction D2, a second area R2 where the plurality of first transmissive mirrors M1 are arranged side by side along the first direction D1, and a third area R3 where the plurality of second transmissive mirrors M2 are arranged side by side along the second direction D2. The first area R1, the second area R2, and the third area R3 are arranged side by side in the order of the second area R2, the first area R1, and the third area R3.SELECTED DRAWING: Figure 2

Description

The present invention relates to a virtual image display device and a pupil enlargement element that enable display of a virtual image.

2. Description of the Related Art A known virtual image display device includes a display element and an eyepiece, and a pupil enlarging element composed of two diffraction gratings is arranged between the eyepiece and the exit pupil (see Patent Document 1).

JP-A-7-72422

In the apparatus of the prior art document, it is possible to increase the width of the exit pupil formed by the eyepiece while avoiding an increase in the size of the eyepiece. However, since the diffraction angle of the diffraction element varies depending on the wavelength of the incident light, for example, when performing display over a wide wavelength range, such as color display, there is a problem that color unevenness occurs in which the color varies depending on the position of the enlarged exit pupil. be.

A virtual image display device according to one aspect of the present invention includes an image forming device that emits image light, and a pupil enlarging element disposed between the image forming device and an exit pupil formed by the image forming device. The element has a plurality of first transmissive mirrors and a plurality of second transmissive mirrors for reflecting image light between an incident surface on which image light is incident and an exit surface from which image light is emitted. The transmissive mirror is inclined toward the exit surface with respect to a first direction in which the pupil enlarging element extends, and the second transmissive mirror is inclined with respect to a second direction opposite to the first direction in which the pupil enlarging element extends. the pupil enlarging element includes a first area in which a first transparent mirror and a second transparent mirror are arranged side by side along the second direction; a plurality of second regions arranged side by side along the second direction; and a third region where a plurality of second transmissive mirrors are arranged side by side along the second direction. The third regions are arranged in order of the second region, the first region, and the third region.

FIG. 2 is a plan view for explaining the mounting state of the virtual image display device of the first embodiment; FIG. 2 is a conceptual plan view for explaining the virtual image display device of FIG. 1; FIG. 4A is a conceptual front view, a cross-sectional plan view, and a rear view illustrating a pupil enlarging element; It is sectional drawing which expanded a part of pupil expansion element. It is a plane sectional view explaining the pupil enlarging element of a modification. It is a top view explaining the example of an imaging optical system. It is a plane sectional view explaining the virtual image display device of 2nd Embodiment.

[First Embodiment]
A virtual image display device according to a first embodiment of the present invention and a pupil enlarging element incorporated therein will be described below with reference to FIG. 1 and the like.

FIG. 1 is a diagram illustrating a wearing state of a head-mounted display (hereinafter also referred to as HMD) 200. The HMD 200 allows an observer or a wearer US who wears the HMD 200 to recognize an image as a virtual image. In FIG. 1 and the like, X, Y, and Z are orthogonal coordinate systems, and the +X direction corresponds to the lateral direction in which both eyes EY of an observer or wearer US wearing the HMD 200 or virtual image display device 100 are aligned, The +Y direction corresponds to the upward direction orthogonal to the horizontal direction in which both eyes EY are aligned for the wearer US, and the +Z direction corresponds to the forward direction or the front direction for the wearer US. The ±Y directions are parallel to the vertical axis or vertical direction.

The HMD 200 includes a first virtual image display device 100A for the right eye, a second virtual image display device 100B for the left eye, and a support device 100C including a pair of temples and supporting the virtual image display devices 100A and 100B. The first virtual image display device 100A is arranged to cover the front of the eye EY of the wearer US, that is, the +Z side. The first virtual image display device 100A includes an image forming device 101 arranged on the outside world side away from the eye EY, and a pupil enlarging element 50 arranged on the eye EY side, which is the inner side. The first virtual image display device 100A and the second virtual image display device 100B are optically mirror-reversed, and hereinafter, the first virtual image display device 100A for the right eye will be described as a representative virtual image display device 100. do.

FIG. 2 is a conceptual plan view for explaining the optical structure of the virtual image display device 100. FIG. The virtual image display device 100 includes an image forming device 101 , a pupil enlarging element 50 and a control device 13 . The image forming apparatus 101 and the pupil enlarging element 50 are supported by the supporting device 100C shown in FIG. 1, and the control device 13 is built in a case (not shown) of the supporting device 100C. The image forming device 101 is also called an image projection module and includes a display element 11 and an imaging optical system 12 . The display element 11 is, for example, an organic EL (Organic Electro-Luminescence), an inorganic EL, or an LED array display, and forms a color still image or moving image on a two-dimensional display surface. The display element 11 is not limited to a self-luminous image light generating device, but is configured by a light modulation element such as an LCD, and forms an image by illuminating the light modulation element with a light source such as a backlight. may As the display element 11, instead of the LCD, an LCOS (Liquid crystal on silicon, LCoS is a registered trademark), a digital micromirror device, or the like can be used. The imaging optical system 12 collimates the image light ML emitted from the display element 11 and makes it enter the eye EY. At this time, the imaging optical system 12 converges the principal ray ML0 of the image light ML emitted from each point on the display surface 11a of the display element 11 toward the original position of the exit pupil P1. The imaging optical system 12 includes an optical element that enables see-through viewing, and transmits the external light OL. Although details will be described later, the pupil enlarging element 50 expands the beam width of the image light ML collimated by the imaging optical system 12 while being collimated. The image light ML with the expanded beam width is collected at the expanded pupil position P2. The control device 13 operates the display device 11 based on an image signal acquired from a communication unit (not shown) or an image signal generated inside, and displays a video such as a moving image or a still image on the display surface 11a.

The shape and structure of the pupil enlarging element 50 will be described with reference to FIG. 3, area AR1 is a front view of pupil enlarging element 50, area AR2 is a plane sectional view of pupil enlarging element 50, and area AR3 is a rear view of pupil enlarging element 50. FIG. The pupil enlarging element 50 is a parallel plate-shaped member, and includes an incident surface 51 on which image light is incident, an exit surface 52 from which image light is emitted, a plurality of first transparent mirrors M1 that reflect image light, and image light. and a plurality of second transmissive mirrors M2 for reflecting the . Anti-reflection films 55 and 56 are formed on the incident surface 51 and the exit surface 52 from the viewpoint of preventing stray light and reducing loss of light quantity. The pupil enlarging element 50 includes a central first region R1, a second region R2, and a third region R3 when viewed as an optical function. In the first region R1, the first transmissive mirror M1 and the second transmissive mirror are arranged side by side along the second direction D2. Here, the second direction D2 is the direction from one end 50a to the other end 50b of the pupil enlarging element 50 when a horizontal cross section parallel to the XZ plane is observed from the vertical direction. In the second region R2, a plurality of first transmissive mirrors are arranged side by side along the first direction. Here, the first direction D1 is the direction from the other end 50b to the one end 50a of the pupil enlarging element 50 when a horizontal cross section parallel to the XZ plane is observed from the vertical direction, and is the opposite direction of the second direction D2. corresponds to In the third region R3, a plurality of second transmissive mirrors are arranged side by side along the second direction D2. In the above description, the pupil enlarging element 50 is divided into the first region R1, the second region R2, and the third region R3. It may be considered by dividing it into two along the longitudinal section. In this case, the −X side half of the first region R1 and the second region R2 form the first half region RR1, and the +X side half of the first region R1 and the third region R3 form the second half region RR2. is formed.

In the first region R1 provided in the center of the pupil enlarging element 50, the first translucent member T1, which is a columnar prism with a triangular cross section, is arranged between the first transmissive mirror M1 and the second transmissive mirror M2. In the second region R2 on the −X side, a second light-transmitting member T2, which is a columnar prism having a parallelogram cross section, is arranged between the adjacent first transmitting mirrors M1. A first outer translucent member T22, which is a trapezoidal columnar prism, is arranged. In the third region R3 on the +X side, a second light-transmitting member T2, which is a columnar prism with a parallelogram cross section, is arranged between the adjacent second transmissive mirrors M2. A second outer translucent member T23, which is a prism, is arranged. The first transparent mirror M1 is a half mirror and has a transmittance of, for example, 40%. The second transparent mirror M2 is a half mirror and has a transmittance of, for example, 40%.

The first region R1 of the pupil enlarging element 50 includes the inner half of the inner first translucent member T1, the first transmissive mirror M1, the second transmissive mirror M2, and the pair of outer second translucent members T2. and a pair of triangular prisms where The second region R2 includes, from the inside near the optical axis AX to the outside, a triangular prism that is the outer half of the second light-transmitting member T2, a plurality of first transmitting mirrors M1, and a plurality of second light-transmitting members. T2 and a first outer translucent member T22. The multiple first transmissive mirrors M1 and the multiple second translucent members T2 are alternately arranged. The third region R3 includes, from the inside near the optical axis AX to the outside, a triangular prism that is the outer half of the second light-transmitting member T2, a plurality of second transmitting mirrors M2, and a plurality of second light-transmitting members. T2 and a second outer translucent member T23. The plurality of second transparent mirrors M2 and the plurality of second light transmitting members T2 are alternately arranged. In the above, the first light-transmitting member T1, the second light-transmitting member T2, the first outer light-transmitting member T22, and the second outer light-transmitting member T23 are made of glass, but they can also be made of an optical resin material. can. By using the translucent members T1, T2, T22 and T23, it is possible to spatially precisely and stably arrange the first transmissive mirror M1 and the second transmissive mirror M2. As a result, it becomes easy to make the structure of the pupil enlarging element 50 highly precise, and the pupil enlarging element 50 is easily incorporated.

FIG. 4 is a partially enlarged cross-sectional view for explaining the structure and support of the first transparent mirror M1. The first transmissive mirror M1 is a dielectric multilayer film supported by the flat slope Sa of the first translucent member T1. The first transmissive mirror M1 is formed as a thin film on the slope Sa by a film forming method such as vapor deposition or sputtering, and its transmittance is adjusted. The first transparent mirror M1 is sandwiched between the slope Sa of the first light-transmitting member T1 and the slope Sb of the second light-transmitting member T2. It is joined to the translucent member T2 via a transparent adhesive layer CL. The first transmissive mirror M1 is not limited to a dielectric multilayer film, and can be formed of a metal thin film such as aluminum or silver, or may be a composite of a dielectric multilayer film and a metal thin film. The structure and supporting state of the second transparent mirror M2 shown in FIG. 3 are the same as the structure and supporting state of the first transparent mirror M1, and therefore the description thereof is omitted.

An example of a method for manufacturing the pupil enlarging element 50 will be described. A parallelogram prism block, a triangular prism block, etc. are prepared, and a half mirror film is formed on specific side surfaces of these prism blocks. These prism blocks are laminated and adhered in a predetermined direction so that the half mirror film has the desired inclination and arrangement, cut into plates, and the surfaces to be the incident surface 51 and the exit surface 52 are polished to prevent reflection. By forming the membranes 55, 56, the pupil enlarging element 50 is obtained.

Returning to FIGS. 2 and 3, the plurality of first transmissive mirrors M1 are equally inclined toward the exit surface 52 with respect to the first direction D1 in which the pupil enlarging element 50 extends. The inclination of each first transmissive mirror M1 is such that it opposes the rays of the image light ML incident on the respective locations. The tilt angle α1 of the first transmissive mirror M1 with respect to the first direction D1 is set to the same 45°. The tilt angle α1 of the first transmissive mirror M1 is the angle of the first transmissive mirror M1 with respect to the incident surface 51 and the exit surface 52 .

The multiple second transmissive mirrors M2 are equally inclined toward the exit surface 52 with respect to the second direction D2 in which the pupil enlarging element 50 extends. The inclination of each second transmissive mirror M2 is such that it opposes the rays of the image light ML incident thereon. The tilt angle α2 of the second transmissive mirror M2 with respect to the second direction D2 is set to the same 45°. The tilt angle α2 of the second transmissive mirror M2 is the angle of the second transmissive mirror M2 with respect to the incident surface 51 and the exit surface 52 .

The first transmissive mirror M1 and the second transmissive mirror M2 are arranged at equal intervals so as not to separate or overlap when viewed from the front and rear ±Z directions. Here, the arrangement interval of the first transparent mirror M1 and the arrangement interval of the second transparent mirror M2 are equal to the thickness t of the pupil enlarging element 50 in the front-rear direction. The thickness t of the pupil enlarging element 50 in the front-rear direction is several millimeters.

The absolute value of the angle β1=−45° formed by the first transparent mirror M1 and the normal to the entrance surface 51 of the pupil enlarging element 50 is 45°, and The absolute value 45° of the angle β2=45° formed with the normal line is the same. Here, the positive angle is clockwise. The fact that the absolute value of the angle β1 and the absolute value of the angle β2 are the same includes not only the state in which they exactly match but also the case in which there is deviation or difference due to manufacturing tolerances or the like. A specific allowable value for the relative angular deviation of the first transmissive mirror M1 and the like is 0.01° or less, and such relative differences are considered to be the same.

In the second region R2 or the first half-region RR1, the image light ML and the external light OL that have entered the incident surface 51 of the pupil enlarging element 50 enter the first transparent mirror M1 and are partially transmitted while being partially transmitted. , is incident on the adjacent first transparent mirror M1 on the outer side, is partially reflected, travels parallel to the original, and is emitted to the outside through the exit surface 52. As shown in FIG. The image light ML transmitted through the first transmissive mirror M1 and the image light ML and external light OL reflected twice by the first transmissive mirror M1 have the same exit angle. In other words, the image light ML and the external light OL that have passed through the first transparent mirror M1 and the image light ML and the external light OL that have been reflected by the first transparent mirror M1 an even number of times are superimposed in a parallel state. Increases beam width. As a result, the image can be observed even if the position of the eye EY is greatly moved in the lateral direction, and the allowable range of positional deviation of the eye EY is widened. However, the light that has traveled straight through the inner first transparent mirror M1 is reduced to 40%, given that the reflectance of the first transparent mirror M1 is 60%, and is reflected by the inner first transparent mirror M1. The light reflected by the first transmissive mirror M1 and superimposed on the straight light is attenuated to 36%. The image light ML reflected by the first transparent mirror M1 and transmitted through the adjacent first transparent mirror M1 is further incident on the adjacent first transparent mirror M1 and partially reflected to return to the original image light. It travels parallel to ML and is emitted to the outside through the exit surface 52, but passes through the first transparent mirror M1 once while being reflected twice by the first transparent mirror M1. It is greatly dimmed. Since the angle of the image light ML and the external light OL does not change even after passing through the pupil enlarging element 50, no image distortion occurs in the case of a distant image.

On the other hand, in the third region R3 or the second half region RR2, the image light ML and the external light OL that have entered the incident surface 51 of the pupil enlarging element 50 enter the second transparent mirror M2 and are partially transmitted. The light is partially reflected, enters the adjacent second transmissive mirror M2 on the outside, is partially reflected, travels parallel to the original, and exits through the exit surface 52 to the outside. The image light ML that has passed through the second transparent mirror M2 and the image light ML and the external light OL that have been reflected twice by the second transparent mirror M2 have the same emission angle. That is, the image light ML and the external light OL that have passed through the second transparent mirror M2 and the image light ML and the external light OL that have been reflected by the second transparent mirror M2 an even number of times are superimposed in parallel. Increases beam width. However, the light that has traveled straight through the inner second transparent mirror M2 is reduced to 40%, given that the second transparent mirror M2 has a reflectance of 60%, and is reflected by the inner second transparent mirror M2. The light reflected by the second transmissive mirror M2 and superimposed with the straight light is attenuated to 36%. The image light ML reflected by the second transparent mirror M2 and transmitted through the adjacent second transparent mirror M2 is further incident on the adjacent second transparent mirror M2 and partially reflected to return to the original image light. It travels parallel to ML and is emitted to the outside through the exit surface 52, but passes through the second transparent mirror M2 once while being reflected twice by the second transparent mirror M2. It is greatly dimmed. Since the angle of the image light ML and the external light OL does not change even after passing through the pupil enlarging element 50, no image distortion occurs in the case of a distant image.

More specifically, consider the central group of rays LG1 parallel to the optical axis AX of the imaging optical system 12 . The central light group LG1 enters the first region R1 of the pupil enlarging element 50, and (1) passes through the first transmissive mirror M1 in the first region R1 and (2) the first light beam in the first region R1. (3) light transmitted through the second transmissive mirror M2 in the first region R1; (4) After being reflected by the second transmissive mirror M2 in the first region R1, the beams reflected by the second transmissive mirror M2 in the third region R3 are spliced together to form a group of rays LG12 with an expanded beam width. .

Consider a light ray group LG2 from right oblique directions (that is, -X and +Z directions) forming a large angle with respect to the optical axis AX of the imaging optical system 12 . The right oblique light group LG2 enters the second region R2 of the pupil enlarging element 50, and (1) passes through the first transparent mirror M1 in the second region R2, and (2) passes through the first transparent mirror M1. (3) reflected by the first transparent mirror M1, transmitted by the first transparent mirror M1, and further outside By joining together the light beams reflected by the adjacent first transparent mirror M1, a light beam group LG22 having an expanded light beam width is obtained.

Consider a light ray group LG3 from left oblique directions (that is, +X and +Z directions) forming a large angle with respect to the optical axis AX of the imaging optical system 12 . The left oblique light group LG3 enters the third region R3 of the pupil enlarging element 50, and (1) passes through the second transmissive mirror M2 in the third region R3, and (2) passes through the second transmissive mirror M2. (3) reflected by the second transparent mirror M2, transmitted by the second transparent mirror M2, and further outside By joining together the light beams reflected by the adjacent second transparent mirror M2, a light beam group LG32 having an expanded light beam width is obtained.

The light group LG12, the light group LG22, and the light group LG32 as described above realize an exit pupil P2 that is enlarged more than the original exit pupil P1 when the pupil enlarging element 50 is not provided. It should be noted that the width of the luminous flux of the image light ML that enters the first region R1 like the light group LG12 and exits from the pupil enlarging element 50 (that is, the width of the light group LG12) is the same as the second region R2 or the third region R3. is wider than the width of the light flux of the image light ML that is incident on and emitted from the pupil enlarging element 50 (that is, the width of the light groups LG22 and LG32).

FIG. 5 is a cross-sectional view for explaining a pupil enlarging element 50 of a modification. In this case, protective films 58a and 58b are attached to the entrance side and the exit side of the pupil enlarging element 50 to prevent fragments from scattering when the pupil enlarging element 50 is damaged. Antireflection films 55 and 56 are formed on the surfaces of the protective films 58a and 58b.

FIG. 6 is a plan view for explaining a specific example of the imaging optical system 12. As shown in FIG. The imaging optical system 12 includes a projection lens 21 and a light guide 25 . The light guide 25 is formed by bonding a light guide member 71 and a light transmission member 72 via an adhesive layer CC. The light guide member 71 and the light transmission member 72 are made of a resin material exhibiting high light transmittance in the visible range. The light guide member 71 has first to fifth surfaces S11 to S15, of which the first and third surfaces S11 and S13 are planes parallel to each other, and the second, fourth and fifth surfaces. S12, S13, and S15 are convex optical surfaces as a whole, and are composed of, for example, free-form surfaces. The light transmission member 72 has first to third transmission surfaces S21 to S23, of which the first and third transmission surfaces S21 and S23 are planes parallel to each other, and the second transmission surface S22 is the entire surface. is a concave optical surface, for example, a free-form surface. The second surface S12 of the light guide member 71 and the second transmission surface S22 of the light transmission member 72 have the same shape in which the unevenness is reversed, and the partial reflection surface MC is formed on one surface of both.

A pupil enlarging element 50 is arranged to face the first surface S11, which is the light exit surface 25e of the light guide 25, and the first transmission surface S21.

An outline of the optical path of the image light ML will be described below. The light guide member 71 guides the image light ML emitted from the projection lens 21 toward the observer's eyes by reflection on the first to fifth surfaces S11 to S15. Specifically, the image light ML from the projection lens 21 first enters the fourth surface S14, is reflected by the fifth surface S15, which is the inner surface of the reflective film RM, and enters the fourth surface S14 again from the inside. It is totally reflected, enters the third surface S13 and is totally reflected, enters the first surface S11 and is totally reflected. The image light ML totally reflected by the first surface S11 is incident on the second surface S12, partially transmitted through the partially reflecting surface MC provided on the second surface S12, and partially reflected by the first surface S12. It reenters and passes through S11. The image light ML that has passed through the first surface S11 has its beam diameter enlarged by the pupil enlarging element 50, and enters the position of the exit pupil P2 where the observer's eye EY is arranged as a substantially parallel beam. That is, the observer observes the image with the image light ML as a virtual image.

The light guide member 25 allows the observer to visually recognize the image light ML through the light guide member 71, and allows the observer to observe an external image with little distortion in a state in which the light guide member 71 and the light transmission member 72 are combined. It has become. At this time, since the third surface S13 and the first surface S11 are planes substantially parallel to each other (diopter is substantially 0), almost no aberration or the like is caused in the external light OL. Further, the third transmission surface S23 and the first transmission surface S21 are planes substantially parallel to each other. Furthermore, since the third transmitting surface S23 and the first surface S11 are planes substantially parallel to each other, almost no aberrations or the like occur. As described above, the observer observes an external image without distortion through the light guide member 71 and the light transmission member 72 .

The virtual image display device 100 of the first embodiment includes an image forming device 101 that emits image light ML, and a pupil enlarging element 50 arranged between the image forming device 101 and an exit pupil P2 formed by the image forming device 101. The pupil enlarging element 50 includes a plurality of first transmissive mirrors M1 for reflecting the image light ML and a plurality of and a second transparent mirror M2, the first transparent mirror M1 is inclined toward the exit surface 52 with respect to the first direction D1 in which the pupil enlarging element 50 extends, and the second transparent mirror M2 is The pupil enlarging element 50 is inclined toward the exit surface 52 with respect to the second direction D2 opposite to the first direction D1 in which the pupil enlarging element 50 extends, and the pupil enlarging element 50 includes a first transparent mirror M1 and a second transparent mirror M2. are aligned along the second direction D2, a second region R2 is a plurality of first transmissive mirrors M1 aligned along the first direction D1, and a second transmissive mirror M2 has a plurality of third regions R3 arranged side by side along the second direction D2, and the second region R2, the first region R1, and the third region R3 are arranged side by side in this order.

In the virtual image display device 100, assuming that the collimated image light ML is emitted from the image forming device 101, in the first region R1 and the second region R2 provided at one end 50a from the center of the pupil enlarging element 50, adjacent The image light ML can be partially shifted in the first direction D1 by the plurality of matching first transmissive mirrors M1, and the luminous flux width of the image light ML can be widened without causing color unevenness. Further, in the first region R1 and the third region R3 provided from the center to the other end 50b of the pupil enlarging element 50, the image light ML is partially diverted in the second direction D2 by the plurality of adjacent second transparent mirrors M2. It can be shifted, and the luminous flux width of the image light ML can be widened without causing color unevenness. That is, the pupil size in the first direction D1 or the second direction D2 can be enlarged.

[Second embodiment]
A virtual image display device and the like according to the second embodiment of the present invention will be described below. Note that the virtual image display device of the second embodiment is a partial modification of the virtual image display device of the first embodiment, and the description of common parts will be omitted.

A virtual image display device 100 according to the second embodiment will be described with reference to FIG. In the virtual image display device 100 , a polarizing filter 61 is arranged on the outside side of the imaging optical system 12 . The polarizing filter 61 transmits the first polarized light component P whose polarization direction is the X direction, and blocks the second polarized light component S whose polarization direction is the Y direction. It has become.

The display element 11 emits polarized light corresponding to the second polarized component S as the image light ML.

Pupil enlarging element 250 incorporates a plurality of first transmissive mirrors PM1 and a plurality of second transmissive mirrors PM2. The first transmissive mirror PM1 is not a half mirror like the first transmissive mirror M1 of the first embodiment shown in FIG. 2, but a polarization separation film and functions as a polarizer. Similarly, the second transmissive mirror PM2 is not a half mirror like the second transmissive mirror M2 of the first embodiment shown in FIG. 2, but a polarization separation film and functions as a polarizer.

The image light ML emitted from the imaging optical system 12 has a second polarization component S. Here, the second polarization component S is the polarization perpendicular to the plane of incidence, which is perpendicular to the first and second transmissive mirrors PM1 and PM2 and extends parallel to the XZ plane. In other words, the plane of polarization of the second polarization component S is parallel to the ±Y directions, which are the second polarization directions. On the other hand, the first polarization component P is polarized light parallel to the plane of incidence that is perpendicular to the first transparent mirror PM1 and the second transparent mirror PM2 and extends parallel to the XZ plane. That is, the plane of polarization of the first polarization component P is parallel to the ±X directions, which are the first polarization directions. The image light ML having the second polarization component S is reflected by the first transmissive mirror PM1 and the second transmissive mirror PM2 of the pupil enlarging element 250, and the optical path is directed outward (that is, the first direction D1 and the second direction D2). shift to The reflectance of the first transmissive mirror PM1 and the second transmissive mirror PM2 with respect to the second polarized component S is, for example, about 60%. R1, the second region R2, and the third region R3 are enlarged in the horizontal direction, that is, in the ±X direction.

On the other hand, the reflectance of the first transparent mirror PM1 and the second transparent mirror PM2 with respect to the first polarized component P is approximately 0%.

Due to the polarizing filter 61, only the first polarized component P of the external light OL enters the pupil enlarging element 250, and the external light OL that has passed through the imaging optical system 12 passes through the pupil enlarging element 250 without being substantially reflected. . Since external light coming from a short distance is not parallel light, ghost light is generated when reflected by a plurality of adjacent transmissive mirrors. is suppressed, and objects in the outside world can be seen clearly.

[Modifications and others]
Although the present invention has been described with reference to the above embodiments, the present invention is not limited to the above embodiments, and can be implemented in various aspects without departing from the scope of the invention. A modification such as is also possible.

The imaging optical system 12 incorporated in the virtual image display device 100 is not limited to the one illustrated in FIG. 6, and can have various configurations. For example, in the example shown in FIG. 6, the imaging optical system 12 is a horizontal off-axis optical system that is asymmetric in the X direction or horizontal direction. It can also be an off-axis optical system. As for the optical elements constituting the imaging optical system 12, those shown in FIG. 6 are merely examples, and the light guide member 71 and the light transmission member 72 can be replaced with lenses, mirrors, and the like.

The number and arrangement intervals of the first transparent mirror M1 and the second transparent mirror M2 constituting the pupil enlarging element 50 are not limited to those illustrated in FIG. It can be adjusted accordingly.

A vision correction lens can be detachably arranged on the eye EY side of the pupil enlarging element 50 . The vision correcting lens may be fixed to the pupil enlarging element 50 , but it can also be fixed to the support of the pupil enlarging element 50 or the imaging optical system 12 .

The imaging optical system 12 can be a non-see-through type optical system that does not transmit the external light OL. In this case, the virtual image display device 100 becomes a closed-type virtual image display device.

In the above description, it is assumed that the virtual image display device 100 is worn on the head and used. However, the virtual image display device 100 can also be used as a handheld display that can be viewed like binoculars without being worn on the head. .

A virtual image display device in a specific aspect includes an image forming device that emits image light, and a pupil enlarging element disposed between the image forming device and an exit pupil formed by the image forming device. has a plurality of first transmissive mirrors and a plurality of second transmissive mirrors for reflecting image light between an incident surface on which image light is incident and an exit surface from which image light is emitted; The mirror is inclined toward the exit surface with respect to a first direction in which the pupil enlarging element extends, and the second transmissive mirror is inclined with respect to a second direction opposite to the first direction in which the pupil enlarging element extends. The pupil enlarging element includes a first area in which a first transmissive mirror and a second transmissive mirror are arranged side by side along a second direction, and a first area in which the first transmissive mirror is arranged in the first direction. and a third region in which a plurality of second transmissive mirrors are arranged side by side along the second direction, the first region, the second region, and the second region The three regions are arranged in order of the second region, the first region, and the third region.

In the virtual image display device, assuming that collimated image light is emitted from the image forming device, a plurality of adjacent first transmissive light beams are formed in the first region and the second region provided at one end from the center of the pupil enlarging element. The image light can be partially shifted in the first direction by the mirror, and the luminous flux width of the image light can be widened without causing color unevenness. Further, in the first region and the third region provided from the center to the other end of the pupil enlarging element, the image light can be partially shifted in the second direction by the plurality of adjacent second transmissive mirrors. The luminous flux width of image light can be widened without causing unevenness. That is, the pupil size in the first direction or the second direction can be enlarged.

In a specific aspect, a translucent member is arranged between adjacent transmissive mirrors, and the pupil enlarging element is a flat member. In this case, it becomes easy to make the structure of the pupil enlarging element highly accurate, and it becomes easy to incorporate the pupil enlarging element.

In a specific aspect, the translucent member is made of glass or a resin material.

In a specific aspect, the transmissive mirror is a dielectric multilayer film or a metal film.

In a specific embodiment, the absolute value of the angle between the normal to the entrance surface of the pupil enlarging element and the first transmissive mirror and the absolute value of the angle between the normal to the entrance surface and the second transmissive mirror are approximately are identical. In this case, the pupil enlarging element can be made symmetrical with respect to the first direction and the second direction, and the symmetry of the image quality of the displayed image can also be enhanced.

In a specific embodiment, the first transmissive mirror and the second transmissive mirror are arranged obliquely opposite the light rays incident on the respective locations. In this case, the light passing through between the adjacent transmissive mirrors without being reflected is suppressed, and the luminous flux width of the image light can be reliably widened.

In a specific aspect, an antireflection layer is formed on the entrance surface and the exit surface. In this case, reflection loss of image light can be reduced.

In a specific embodiment, the width of the image light beam that enters the first region and exits from the pupil enlarging element is wider than the width of the image light beam that enters the second region and exits from the pupil enlarging element. wide.

In a specific aspect, a polarizing filter is arranged on the outside world side of the image forming apparatus, and the first transmissive mirror and the second transmissive mirror transmit the light in the first polarization direction transmitted by the polarizing filter, It reflects light in a second polarization direction that is different from the polarization direction. In this case, since there is no pupil enlarging function for light from the outside world (see-through light), it is possible to suppress the occurrence of a ghost image when looking at an object in the outside world.

In a specific aspect, the imager emits a second polarization.

In a specific aspect, the pupil enlarging element includes an incident surface on which image light is incident, an exit surface from which image light is emitted, and a plurality of first transmissive elements arranged between the incident surface and the exit surface and reflecting image light. A mirror and a plurality of second transmissive mirrors disposed between the entrance surface and the exit surface for reflecting image light, the first transmissive mirrors being oriented with respect to a first direction in which the pupil enlarging element extends. the second transmissive mirror is inclined toward the exit surface with respect to a second direction opposite to the first direction in which the pupil enlarging element extends; a first region in which a mirror and a second transmissive mirror are arranged side by side along a second direction; a second region in which a plurality of first transmissive mirrors are arranged side by side along the first direction; and a third region in which a plurality of transmissive mirrors are arranged side by side along the second direction, and the first region, the second region, and the third region are are arranged in order.

DESCRIPTION OF SYMBOLS 11... Display element 11a... Display surface 12... Imaging optical system 13... Control apparatus 50... Pupil expansion element 50a... One end 50b... The other end 51... Entrance surface 52... Exit surface 55,56 Antireflection film 58a, 58b Protective film 100 Virtual image display device 100A, 100B Virtual image display device 100C Support device 101 Image forming device 250 Pupil enlarging element AX Optical axis CC Adhesive layer, CL... Adhesive layer, EY... Eye, LG1, LG12... Group of rays, LG2, LG22... Group of rays, LG3, G32... Group of rays, MC... Partial reflection surface, ML... Image light, ML0... Chief ray, OL ... external light, P1, P2 ... exit pupil, T1, T2, T22, T23 ... translucent member, US ... wearer

Claims (10)

an image forming device that emits image light;
a pupil enlarging element disposed between the image forming device and an exit pupil formed by the image forming device;
The pupil enlarging element includes a plurality of first transmissive mirrors and a plurality of second transmissive mirrors for reflecting the image light between an incident surface on which the image light is incident and an exit surface from which the image light is emitted. have
the first transmissive mirror is inclined toward the exit surface with respect to a first direction in which the pupil enlarging element extends;
the second transmissive mirror is inclined toward the exit surface with respect to a second direction opposite to the first direction in which the pupil enlarging element extends;
The pupil enlarging element includes a first region in which the first transparent mirror and the second transparent mirror are arranged side by side along the second direction, and the first transparent mirror is arranged in the first direction. and a third region in which a plurality of the second transmissive mirrors are arranged side by side along the second direction,
The virtual image display device, wherein the first area, the second area, and the third area are arranged in order of the second area, the first area, and the third area. A translucent member is arranged between the adjacent transmissive mirrors,
2. The virtual image display device according to claim 1, wherein said pupil enlarging element is a flat member. 3. The virtual image display device according to claim 2, wherein the translucent member is made of glass or a resin material. 4. The virtual image display device according to claim 1, wherein said transparent mirror is a dielectric multilayer film or a metal film. The absolute value of the angle formed by the normal to the entrance surface of the pupil enlarging element and the first transmissive mirror is substantially the same as the absolute value of the angle formed by the normal to the entrance surface and the second transmissive mirror. The virtual image display device according to any one of claims 1 to 4. The virtual image display according to any one of claims 1 to 5, wherein the first transmissive mirror and the second transmissive mirror are arranged obliquely so as to face light rays incident thereon. Device. The virtual image display device according to any one of claims 1 to 6, wherein an antireflection layer is formed on the entrance surface and the exit surface. The width of the image light beam that enters the first region and exits from the pupil enlarging element is wider than the width of the image light beam that enters the second region and exits from the pupil enlarging element. The virtual image display device according to any one of claims 1 to 7, which is wide. A polarizing filter is arranged on the outside world side of the image forming apparatus,
The first transparent mirror and the second transparent mirror transmit light in a first polarization direction transmitted by the polarizing filter, and reflect light in a second polarization direction different from the first polarization direction. Item 9. The virtual image display device according to any one of Items 1 to 8. an incident surface on which the image light is incident;
an exit surface from which the image light exits;
a plurality of first transmissive mirrors arranged between the entrance surface and the exit surface for reflecting the image light;
a plurality of second transmissive mirrors disposed between the incident surface and the exit surface and reflecting the image light;
the first transmissive mirror is inclined toward the exit surface side with respect to the first direction in which the pupil enlarging element extends;
the second transmissive mirror is inclined toward the exit surface with respect to a second direction opposite to the first direction in which the pupil enlarging element extends;
The pupil enlarging element includes a first region in which the first transparent mirror and the second transparent mirror are arranged side by side along the second direction, and the first transparent mirror is arranged in the first direction. and a third region in which a plurality of the second transmissive mirrors are arranged side by side along the second direction,
A pupil enlarging element, wherein the first region, the second region, and the third region are arranged in order of the second region, the first region, and the third region.

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