Virtual image display device and optical unit

Abstract

To prevent a component other than image light from leaking to the outside, and prevent an image from being easily seen from the outside.SOLUTION: A virtual image display device 110 comprises: a display panel 11a that is a display element emitting image light ML; a light guide member 51a that has a first total reflection surface 51i and a second total reflection surface 51o; a first diffraction element DE1 on a light incident side that is provided additionally to the light guide member 51a; a second diffraction element DE2 on a light emission side that is provided additionally to the light guide member 51a; and a stray light prevention filter 51s that is provided on an external side of an image take-out unit IO provided with the second diffraction element DE2, and restricts passage of diffraction light caused by the second diffraction element DE2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a virtual image display device and an optical unit that enable the viewing of a virtual image, and in particular to a type of virtual image display device that utilizes diffraction and light guiding. [Background technology]

[0002] A display device that enables the observation of a virtual image is known which comprises a light-guiding member into which image light emitted from an image light generating device is incident, a first diffraction element provided on the incident side of the light-guiding member and having positive power, a second diffraction element provided on the exit side of the light-guiding member and having positive power, and a mirror provided at the end of the incident side of the light-guiding member and having positive power, in which the image light that passes through the first diffraction element is reflected by the mirror and propagates within the light-guiding member, and the image light that is incident on the second diffraction element is deflected by the second diffraction element to form an exit pupil (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-156995 Summary of the Invention [Problem to be solved by the invention]

[0004] In a display device such as that shown in Patent Document 1, there is a possibility that components other than the image light diffracted by the second diffraction element toward the exit pupil may leak out to the outside. In particular, when a diffraction grating is used as the diffraction element, a significant portion of the image light leaks out, making the image easily visible from the outside. [Means for solving the problem]

[0005] A virtual image display device according to one aspect of the present invention includes a display element that emits image light, a light-guiding member having a first total reflection surface and a second total reflection surface, a first diffraction element on the light incident side associated with the light-guiding member, a second diffraction element on the light exit side associated with the light-guiding member, and a stray light suppression filter that is provided on the external side of an image extraction section on which the second diffraction element is provided and that limits the passage of light diffracted by the second diffraction element. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a plan view illustrating a state in which an HMD incorporating a virtual image display device is worn. [Diagram 2] 1 is a side cross-sectional view of a main part of a virtual image display device according to a first embodiment. [Diagram 3] FIG. 4 is an enlarged cross-sectional side view illustrating the function of the stray light suppression filter. [Figure 4] FIG. 11 is a rear view illustrating a main part of the virtual image display device according to the second embodiment. [Diagram 5] FIG. 11 is a rear view illustrating a main part of the virtual image display device according to the third embodiment. [Figure 6] FIG. 13 is a side cross-sectional view illustrating a main part of a virtual image display device according to a fourth embodiment. [Figure 7] 7 is a diagram illustrating the function of the pair of stray light suppression filters shown in FIG. 6. FIG. [Figure 8] 7 is a diagram illustrating a modified example of the virtual image display device shown in FIG. [Figure 9] 7 is a diagram illustrating another modified example of the virtual image display device shown in FIG. [Figure 10] FIG. 13 is a diagram illustrating a main part of a virtual image display device according to a fifth embodiment. [Figure 11] 11 is a diagram illustrating a modified example of the virtual image display device shown in FIG. [Figure 12] FIG. 13 is a diagram illustrating a main part of a virtual image display device according to a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] [First embodiment] Hereinafter, a first embodiment of the virtual image display device according to the present invention will be described in detail with reference to FIG.

[0008] Fig. 1 is a diagram for explaining a wearing state of a head mounted display (hereinafter also referred to as HMD) 200, and the HMD 200 allows an observer or wearer US wearing the HMD 200 to recognize an image as a virtual image. In Fig. 1 and the like, X, Y, and Z are an orthogonal coordinate system, and the +X direction corresponds to the lateral direction in which both eyes EY of the observer or wearer US wearing the HMD 200 or the virtual image display device 110 are aligned, the +Y direction corresponds to the upward direction perpendicular to the lateral direction in which both eyes EY are aligned for the wearer US, and the +Z direction corresponds to the forward direction or front direction for the wearer US. The ±Y directions are parallel to the vertical axis or vertical direction.

[0009] The HMD 200 includes a virtual image display device 110A for the right eye, a virtual image display device 110B for the left eye, and a pair of temples 110C, and is equipped with a support device 120 that supports the pair of virtual image display devices 110A and 110B. The first virtual image display device 110A is disposed so as to cover the front, i.e., +Z side, of the right eye EY of the wearer US, and the second virtual image display device 110B is disposed so as to cover the +Z side of the left eye EY of the wearer US. The second virtual image display device 110B has a structure in which the optical structure of the first virtual image display device 110A is symmetrically inverted with respect to the left and right +X directions. The first virtual image display device 110A will be mainly described below.

[0010] A first virtual image display device 110A will be described with reference to FIG. 2. The virtual image display device 110A shown in FIG. 2 includes a projection device 10 and a control device 80. A virtual image is displayed to the eye EY by the projection device 10. The virtual image display device 110A forms a virtual image using image light having a wavelength in the visible range (specifically, wavelengths of 450 nm to 650 nm) and partially transmits external light in the visible range, and can display a virtual image with an external image as a background. In other words, the virtual image display device 110A is a see-through type virtual image display device.

[0011] The projection device 10 is an optical unit OU, and includes an image light generating device 11 that emits image light ML, a light guiding optical system 50 that emits the image light ML in the visible range as display light GL, and a drive circuit 60 that operates the image light generating device 11. The image light generating device 11 has a display panel 11a and a collimator lens 11b. The image light generating device 11 is disposed on the eye position EP side of the light guiding optical system 50, that is, in the -Z direction. The light guiding optical system 50 has a diffractive light guiding member 51 that extends approximately parallel to the XY plane. The diffractive light guiding member 51 enables color display of, for example, three colors, RGB, and has a light guiding member 51a, an incident diffraction layer 51b, an exit diffraction layer 51c, and a stray light suppression filter 51s. The incident diffraction layer 51b is a first reflective diffraction element DEI1 provided in association with the incident region R1 on one end side of the light guide member 51a, and deflects the image light ML emitted from the image light generating device 11 and passed through the light guide member 51a of the diffractive light guide member 51 upon reflection, making it possible to guide the image light ML inside the light guide member 51a. The exit diffraction layer 51c is a second reflective diffraction element DE2 provided in association with the exit region R2 on the other end side of the light guide member 51a, and deflects the image light ML guided inside the light guide member 51a upon reflection, passes through the light guide member 51a, and emits the image light ML toward the outside where the eye EY is located. The stray light suppression filter 51s suppresses the image light ML from leaking to the outside of the light guide optical system 50, that is, the generation of stray light toward the outside. In other words, the stray light suppression filter 51s prevents stray light, which is a component of the image light ML, from being emitted forward from the exit diffraction layer 51c and observed as eye glow. Here, eye glow is a phenomenon in which image light ML leaks out from a front part of the light guide optical system 50 (an image extraction unit IO described later) corresponding to the eye EY, and the front part emits the image light ML to the outside. The stray light suppression filter 51s is specifically an angle control filter AL, which limits the transmission of light propagating in a direction tilted more than a predetermined angle with respect to the front direction, i.e., the +Z direction. The drive circuit 60 performs signal processing under the control of the control device 80, and causes the display panel 11a to perform a display operation. The projection device 10 or the optical unit OU guides the image light ML generated by the display panel 11a to the eye EY of the wearer US as display light GL, thereby allowing the wearer US to view a virtual image.

[0012] In the projection device 10, the entrance region R1 provided with the entrance diffraction layer 51b and the drive circuit 60 are covered with a cover 91 having light-shielding properties, which prevents leakage of the image light ML from the entrance diffraction layer 51b and stray light generated in the image light generating device 11 from leaking out to the outside. On the other hand, the cover 91 exposes the exit region R2 provided with the exit diffraction layer 51c to the outside in order to enable observation of an outside image, allowing outside light to be incident on the eye position EP.

[0013] The image light generating device 11 will be described in more detail below. In the image light generating device 11, the display panel 11a is a display element or display device that emits image light ML to form an image corresponding to a virtual image, and is specifically a display of various light emitting element arrays such as organic EL (organic electro-luminescence), inorganic EL, and LED, and forms a color still image or moving image on a two-dimensional display surface 11d. The display panel 11a is not limited to a self-luminous image light generating device, but may be composed of an LCD or other light modulation element, and may form an image by illuminating the light modulation element with a light source such as a backlight. As the display panel 11a, instead of an LCD, LCOS (Liquid crystal on silicon, LCoS is a registered trademark), a digital micromirror device, or the like may be used.

[0014] Although not shown, the display panel 11a can be replaced with a combination of a laser light source and a scanning device. The laser light source is a light source of a single wavelength, and can relatively increase the diffraction efficiency in the diffractive light-guiding member 51, and can relatively precisely select the angle of the stray light suppression filter 51s described later.

[0015] The collimator lens 11b is a projection optical system including a lens that collimates incident light, and collimates the image light ML emitted from the display surface 11d of the display panel 11a to a state having a predetermined light beam width, and emits the image light ML toward the incident diffraction layer 51b provided on the diffractive light-guiding member 51 at an inclination angle according to the pixel position. The collimator lens 11b includes one or more lens elements made of resin or glass, and may include a reflecting mirror. The optical surfaces of the optical elements constituting the collimator lens 11b may be any of spherical, aspherical, and free-form surfaces.

[0016] In the diffractive light-guiding member 51 of the light-guiding optical system 50, the light-guiding member 51a is a member formed from a parallel plate, and has a first total reflection surface 51i and a second total reflection surface 51o, which are a pair of flat surfaces extending parallel to the XY plane. The light-guiding member 51a extends in the ±Y direction. Here, the extension direction is the direction in which the light-guiding member 51a mainly extends, and corresponds to the direction from the entrance surface IS to the exit surface ES of the light-guiding member 51a. In the diffractive light-guiding member 51, in the upper region or entrance region R1, i.e., the region on the +Y side, the entrance surface IS, which is a part of the first total reflection surface 51i, is provided on the eye EY side, i.e., the -Z side, of the light-guiding member 51a. In the diffractive light-guiding member 51, in the lower region or exit region R2, i.e., the region on the -Y side, the exit surface ES, which is a part of the first total reflection surface 51i, is provided on the eye EY side, i.e., the -Z side, of the light-guiding member 51a. In the incident region R1 of the diffractive light-guiding member 51, an incident diffraction layer 51b is provided on the opposite side of the eye EY, i.e., the +Z side, as a structure facing the incident surface IS. In the exit region R2 of the diffractive light-guiding member 51, an exit diffraction layer 51c is provided on the opposite side of the eye EY, i.e., the +Z side, as a structure facing the exit surface ES. The total reflection surfaces 51i and 51o, which are a pair of flat surfaces in the light-guiding member 51a, totally reflect and guide the image light ML guided into the light-guiding member 51a through the incident diffraction layer 51b, and guide the image light ML with almost no loss. The light-guiding member 51a is molded from a resin or glass having a thickness of, for example, about 1 to 2 mm and high optical transparency. Glass is easy to ensure surface accuracy, and from this viewpoint, it is suitable as a material for the light-guiding member 51a.

[0017] The incident diffraction layer 51b is formed in a rectangular region parallel to the XY plane on the outer side opposite to the eye EY at the first end E1 of the light guide member 51a facing the collimator lens 11b. The incident diffraction layer 51b and the first end E1 are collectively called an image capture section II. The incident diffraction layer 51b couples the image light ML emitted from the display surface 11d of the display panel 11a and passing through the collimator lens 11b to the inside of the light guide member 51a. The incident diffraction layer 51b is a first diffraction element DE1. The incident diffraction layer (first diffraction element) 51b can be formed integrally with the light guide member 51a, but may also be formed separately from the light guide member 51a and joined or attached to the second total reflection surface 51o of the light guide member 51a. The incident diffraction layer 51b folds back the image light ML incident on it through the incident surface IS so that it propagates inside the light guide member 51a by diffraction action. In the present embodiment, the incident diffraction layer 51b is, for example, a surface relief diffraction grating, more specifically, a diffractive optical element produced by nanoimprinting. A diffractive optical element produced by nanoimprinting is formed by forming fine irregularities on the surface of a material that transmits the image light ML and providing a predetermined optical path difference between adjacent regions, and generates a desired diffraction when reflecting the image light ML. The incident diffraction layer 51b diffracts the image light ML of multiple wavelengths, that is, RGB light, individually. The incident diffraction layer 51b is not limited to a single layer that generates the desired diffraction for the three colors of RGB, but may be a multiple layer that generates the desired diffraction for the three colors of RGB. The incident diffraction layer 51b is not limited to a surface relief diffraction grating, but may be an optical element having a diffraction function such as a volume hologram, that is, a diffraction element. The incident diffraction layer 51b is formed in a pattern that includes many protrusions or grooves that extend linearly in the horizontal X direction and has periodicity in the vertical Y direction. The grating period (pitch) and grating height of the pattern formed in the incident diffraction layer 51b are constant. The grating period of this pattern is set so that the reflection angle or incidence angle in the light guiding member 51a is larger than a critical angle determined by the refractive index of the light guiding member 51a, in order to propagate the image light ML by total reflection in the light guiding member 51a. Note that the incident diffraction layer 51b is not limited to one having periodic irregularities exposed on the surface, and may also be one having interfaces corresponding to the periodic irregularities embedded therein.

[0018] The exit diffraction layer 51c is located on the -Y side, i.e., the lower side, of the entrance diffraction layer 51b. The exit diffraction layer 51c is formed in a rectangular area parallel to the XY plane on the outer side opposite the eye EY at the second end E2 of the light guiding member 51a facing the eye position EP. The exit diffraction layer 51c and the second end E2 are collectively referred to as an image extraction section IO. The exit diffraction layer 51c extracts the image light ML traveling in the -Y direction as a whole in the light guiding member 51a to the outside of the light guiding member 51a. The exit diffraction layer 51c is the second diffraction element DE2. The exit diffraction layer 51c or the second diffraction element DE2 can be formed integrally with the light guiding member 51a, but may also be formed separately from the light guiding member 51a and joined or attached to the second total reflection surface 51o of the light guiding member 51a. When the image light ML is reflected by the total reflection surfaces 51i and 51o of the light guide member 51a and propagates, the exit diffraction layer 51c folds back the image light ML by diffraction at some point and restores the angle information before it is incident on the entrance diffraction layer 51b. In the present embodiment, the exit diffraction layer 51c is, for example, a surface relief diffraction grating, and more specifically, a diffractive optical element manufactured by nanoimprinting. The exit diffraction layer 51c is not limited to a surface relief diffraction grating, and may be an optical element having a diffraction function such as a volume hologram, that is, a diffraction element. The exit diffraction layer 51c includes a number of protrusions or grooves that extend linearly in the horizontal X direction and is formed in a pattern having periodicity in the vertical Y direction. The grating period (pitch) and grating height of the pattern formed on the exit diffraction layer 51c are constant. The grating period of this pattern in the Y direction is made to match the grating period of the entrance diffraction layer 51b in the Y direction. The emission diffraction layer 51c is not limited to one having periodic irregularities exposed on the surface, but may have an interface corresponding to the periodic irregularities embedded therein.

[0019] The stray light suppression filter 51s is disposed outside the emission diffraction layer 51c and has substantially the same shape as the emission diffraction layer 51c. The stray light suppression filter 51s may be attached to the emission diffraction layer 51c, or may be disposed apart from the emission diffraction layer 51c via a support member.

[0020] 3, the stray light suppression filter 51s is a flat light-transmitting member having light-shielding characteristics that depend on the inclination angle in the vertical Y direction. The stray light suppression filter 51s is specifically an angle limiting filter (angle control filter) AL, and has a light-shielding layer 51t whose transmittance becomes substantially zero when the inclination angle or the incident angle in the vertical Y direction exceeds a critical value. In the light-shielding layer 51t, the light-transmitting portion P1 and the light-shielding portion P2 are alternately arranged at a constant period in the vertical Y direction, and the light-transmitting portion P1 and the light-shielding portion P2 extend linearly and uniformly in the horizontal X direction. That is, the light-shielding layer 51t has a structure in which the light-shielding portion P2 is embedded in a flat plate having light transmission. Each light-shielding layer 51t is a member that is thin in the Y direction and corresponds to a louver of a blind. When the diffractive light guide member 51 is projected and observed on the YZ plane, the light shielding layer 51t transmits the light ray L1 that is less than a predetermined angle α (specifically, for example, 70°) with respect to the reference line SL extending in a direction perpendicular to the stray light suppression filter 51s, and shields the light ray L2 that is more than the predetermined angle α (specifically, for example, 70°) with respect to the reference line SL. That is, if the outside light OL is less than the predetermined angle α with respect to the reference line SL on the YZ plane along the paper surface, it passes through the stray light suppression filter 51s and the like, making it possible to observe the outside image. If the angle of view of the virtual image display device 110A is 2α or less, it becomes possible to observe the virtual image superimposed on the outside image up to the corners of the virtual image. However, even if the angle of view of the outside light OL is less than the predetermined angle α with respect to the reference line SL, the component close to the predetermined angle α tends to be partially shielded and the luminance tends to decrease, so that the outside image may be dimmed at the periphery of the field of view.

[0021] Consider the image light ML passing through a specific point of interest DPa, which is the midpoint in the thickness direction of the emission diffraction layer 51c. Of the image light ML, the +1st order diffracted light Ld +1 The inclination angle of the zero-order diffracted light Ld with respect to the reference line SL is equal to or larger than a predetermined angle α, and is blocked by the stray light suppression filter 51s. 0 The inclination angle of the 0th-order diffracted light Ld of the image light ML passing through the point of interest DPb near the +Y direction is equal to or larger than the predetermined angle α with respect to the reference line SL, but is not directed toward the light blocking layer 51t. 0The −1st order diffracted light Ld from the point of interest DPa is blocked by the stray light suppression filter 51s. -1 Although the inclination angle of the -1st order diffracted light Ld from the point of interest DPa with respect to the reference line SL is equal to or larger than the predetermined angle α, the -1st order diffracted light Ld -1 travels in a direction close to the -Y direction and does not leak directly to the outside.

[0022] Although not explained above, among the transmitted light diffracted by the exit diffraction layer 51c, the +2nd order diffracted light is blocked by the stray light suppression filter 51s if the inclination of the +2nd order diffracted light with respect to the reference line SL is equal to or greater than the predetermined angle α. On the other hand, if the inclination of the +2nd order diffracted light with respect to the reference line SL is less than the predetermined angle α, the +2nd order diffracted light is not blocked by the stray light suppression filter 51s and partially passes through the stray light suppression filter 51s. However, the intensity of the +2nd order diffracted light is significantly lower than the intensity of the +1st order diffracted light, and is unlikely to cause noticeable eye glow.

[0023] Hereinafter, the light guide of the image light ML and the formation of a virtual image using the diffractive light guide member 51 will be described. The display panel 11a forms a still image or a moving image in color or a specific color (e.g., green) on the two-dimensional display surface 11d. The image light ML from the display surface 11d passes through the collimator lens 11b and enters the light guide member 51a from the incident surface IS. The image light ML transmitted through the light guide member 51a enters the incident diffraction layer 51b at an angle corresponding to the position of the display surface 11d in the Y direction in a plan view toward the -X direction, and is diffracted by the incident diffraction layer 51b so as to be reflected in an angular direction corresponding to the pitch of the pattern formed thereon. The image light ML diffracted by the incident diffraction layer 51b is propagated while being totally reflected in the light guide member 51a, and proceeds in the -Y direction as a whole. The image light ML propagating in the light guide member 51a in the -Y direction as a whole enters the exit diffraction layer 51c and is diffracted by the exit diffraction layer 51c so as to be reflected in an angular direction corresponding to the pitch of the pattern formed thereon. The image light ML diffracted by the exit diffraction layer 51c passes through the light guide member 51a and is emitted from the exit surface ES toward the eye position EP or pupil position where the eye EY of the wearer US is located. The image light ML emitted from the exit diffraction layer 51c reproduces the angle state when it is emitted from the display surface 11d in the +Y direction, while the pupil size is enlarged in the +Y direction. In other words, the image light ML passes through the diffractive light guide member 51 and the pupil size is enlarged in the vertical direction, so that even if the position of the eye EY is significantly shifted vertically, a virtual image due to the image light ML from the display panel 11a can be observed.

[0024] The control device 80 is a portable terminal operated by the wearer US, and includes a main control device 81, a storage device 82, an interface device 83, and a communication device 84. In the software storage section of the storage device 82, the control device 80 includes application software that runs on a basic program that operates the control device 80, such as software that allows selection of an image to be displayed on the projection device 10, and software that changes the image to be displayed on the projection device 10 depending on the environment.

[0025] In the above, the incident diffraction layer 51b and the exit diffraction layer 51c are described as surface relief diffraction gratings or volume holograms, but the incident diffraction layer 51b and the exit diffraction layer 51c may be other diffraction elements. When the exit diffraction layer 51c is a volume hologram, the +1st order diffracted light transmitted through the exit diffraction layer 51c is weaker than that of a nanoimprint diffractive optical element, but eye glow can be reliably suppressed by providing the stray light suppression filter 51s.

[0026] The virtual image display device 110 or the HMD 200 of the first embodiment described above includes the display panel 11a which is a display element that emits the image light ML, the light guide member 51a having the first total reflection surface 51i and the second total reflection surface 51o, the first diffraction element DE1 on the light incident side provided in association with the light guide member 51a, the second diffraction element DE2 on the light exit side provided in association with the light guide member 51a, and the stray light suppression filter 51s provided on the external side of the image extraction unit IO on which the second diffraction element DE2 is provided, and restricts the passage of the diffracted light by the second diffraction element DE2. In this virtual image display device 110 or the HMD 200, since the stray light suppression filter 51s restricts the passage of the diffracted light by the second diffraction element DE2, it is possible to prevent the image light ML emitted forward from the second diffraction element DE2 from being observed as eye glow. Furthermore, it is possible to prevent the image light ML emitted forward from the second diffraction element DE2 from being viewed as an image by the person facing the person.

[0027] Second Embodiment Hereinafter, a virtual image display device according to a second embodiment of the present invention will be described. 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 a description of the common parts will be omitted.

[0028] As shown in FIG. 4, the diffractive light-guiding member 51 of the light-guiding optical system 50 includes a light-guiding member 51a, an incident diffraction layer 51b, a pupil enlargement grating layer 51e, an exit diffraction layer 51c, and a stray light suppression filter 51s. The incident diffraction layer 51b is a first diffraction element DE1, and is formed with a diffraction pattern that extends linearly in the vertical Y direction and repeats periodically in the horizontal X direction. The exit diffraction layer 51c is a second diffraction element DE2, and is formed with a diffraction pattern that extends linearly in the horizontal X direction and repeats periodically in the vertical Y direction. The pupil enlargement grating layer 51e is a third diffraction element DE3, and is provided on the -X side of the incident diffraction layer 51b to bend the optical path of the image light ML that is guided into the light-guiding member 51 and travels in the -X direction as a whole, so that the image light ML travels in the -Y direction as a whole while maintaining the angle information. The third diffraction element DE3 is interposed between the first diffraction element DE1 and the second diffraction element DE2, and guides the image light ML in a direction (-Y direction) intersecting the diffraction direction (X direction) of the first diffraction element DE1. The pupil enlargement grating layer 51e is formed with a diffraction pattern that extends linearly in a diagonal DS1 direction parallel to the XY plane and repeats periodically in a DS2 direction parallel to the XY plane and perpendicular to the DS1 direction. The DS1 direction is rotated 45° clockwise with respect to the +Y direction, and is an intermediate direction between the -X direction and the +Y direction. The grating period or pitch in the X direction and Y direction of the pattern formed in the pupil enlargement grating layer 51e matches the grating period in the X direction of the pattern formed in the input diffraction layer 51b, and matches the grating period in the Y direction of the pattern formed in the output diffraction layer 51c.

[0029] The image light ML from the image light generating device 11 is incident on the incident diffraction layer 51b through the light guiding member 51a, and is diffracted in an angular direction corresponding to the grating period of the pattern formed on the incident diffraction layer 51b, and is propagated while being totally reflected in the light guiding member 51a, and proceeds in the +X direction as a whole. The image light ML propagated in the +X direction in the light guiding member 51a is diffracted by the pupil enlargement grating layer 51e, and its overall optical path is bent in the -Y direction, and is shifted to a position in the +X direction that reflects the number of reflections until it is diffracted by the pupil enlargement grating layer 51e. In other words, the pupil enlargement grating layer 51e has a role of expanding the horizontal pupil size, which corresponds to the width of the light beam in the horizontal or X direction in which the image light ML is incident on the eye EY. The image light ML propagating in the -Y direction as a whole in the light guiding member 51a through the pupil enlargement grating layer 51e is diffracted by the exit diffraction layer 51c, and is emitted toward the eye EY. The image light ML emitted from the emission diffraction layer 51c reproduces the angular state in the X and Y directions before being emitted from the image light generating device 11 and entering the diffractive light-guiding member 51, while the pupil size is enlarged in the X and Y directions. In other words, the diffractive light-guiding member 51 enlarges the pupil size vertically and horizontally while maintaining the image information.

[0030] In this embodiment, as in the first embodiment, a stray light suppression filter 51s is disposed on the outside of the exit diffraction layer 51c, that is, on the +Z side, and extends over substantially the same area as the exit diffraction layer 51c. The stray light suppression filter 51s functions as an angle control filter AL, and when the inclination angle of the diffracted light of the image light ML that passes through the exit diffraction layer 51c and enters the stray light suppression filter 51s becomes greater than a predetermined value in the vertical Y direction with the +Z direction of the front as a reference, the stray light suppression filter 51s exhibits light blocking properties for the image light ML and prevents the image light ML from leaking out. In other words, the stray light suppression filter 51s can prevent the +1st order diffracted light in the vertical Y direction that passes through the exit diffraction layer 51c and travels to the +Z side from leaking out and being observed as eye glow, or the +1st order diffracted light from being viewed as an image by the person facing the person.

[0031] If the stray light suppression filter 51s is a light-transmitting member having light-shielding characteristics that are dependent on the angle not only in the vertical Y direction but also in the horizontal X direction, the effect of the stray light suppression filter 51s in suppressing eye glow can be enhanced. In order for the stray light suppression filter 51s to have angle control characteristics in the vertical and horizontal directions, it is possible to provide a second light-shielding layer having an angle control function in the XZ plane in addition to a first light-shielding layer (corresponding to the light-shielding layer 51t shown in FIG. 3) having an angle control function in the YZ plane. The second light-shielding layer having an angle control function in the XZ plane has light-transmitting portions and light-shielding portions alternately arranged at a constant period in the horizontal X direction. The stray light suppression filter 51s is not limited to a first light-shielding layer and a second light-shielding layer stacked on top of each other, and may be a first light-shielding layer and a second light-shielding layer integrated together. In this case, the stray light suppression filter 51s has a structure in which light-shielding portions or louvers extending in the X and Y directions are embedded in the light-transmitting layer.

[0032] Third Embodiment Hereinafter, a virtual image display device according to a third embodiment of the present invention will be described. Note that the virtual image display device of the third embodiment is a partial modification of the virtual image display devices of the first and second embodiments, and a description of the common parts will be omitted.

[0033] As shown in FIG. 5, the diffractive light guide member 51 of the light guide optical system 50 includes a light guide member 51a, an incident diffraction layer 51b, a first pupil enlargement grating layer 51ea, a second pupil enlargement grating layer 51eb, a first exit diffraction layer 51ca, a second exit diffraction layer 51cb, and a stray light suppression filter 51s. The incident diffraction layer 51b is a first diffraction element DE1, and is formed with a diffraction pattern that extends linearly in the vertical Y direction and repeats periodically in the horizontal X direction. The first pupil enlargement grating layer 51ea is a third diffraction element DE3, and is formed with a diffraction pattern that extends in a first intermediate direction of the -X direction and the -Y direction and repeats periodically in a first orthogonal direction perpendicular to the first intermediate direction. The second pupil enlargement grating layer 51eb is a third diffraction element DE3, and is formed with a diffraction pattern that extends in a second intermediate direction of the -X direction and the +Y direction (corresponding to the first orthogonal direction of the first intermediate direction) and repeats periodically in a second orthogonal direction perpendicular to the second intermediate direction. The first exit diffraction layer 51ca is a second diffraction element DE2 arranged in the -Y direction of the first pupil enlargement grating layer 51ea, and is formed with a diffraction pattern that extends linearly in the horizontal X direction and repeats periodically in the vertical Y direction. The second exit diffraction layer 51cb is a second diffraction element DE2 arranged in the -Y direction of the second pupil enlargement grating layer 51eb, and is formed with a diffraction pattern that extends linearly in the horizontal X direction and repeats periodically in the vertical Y direction.

[0034] In the above, the incident diffraction layer 51b is disposed, for example, on the opposite side to the first pupil enlargement grating layer 51ea and the second pupil enlargement grating layer 51eb with the light guiding member 51a interposed therebetween.

[0035] The image light ML from the image light generating device 11 is incident on the incident diffraction layer 51b, and is diffracted in an angular direction corresponding to the grating period of the pattern formed on the incident diffraction layer 51b, and is propagated while being totally reflected in the light guiding member 51a, and proceeds in the ±X direction as a whole. The image light ML propagated in the -X direction in the light guiding member 51a through the incident diffraction layer 51b is diffracted by the first pupil enlargement grating layer 51ea, and its overall optical path is bent in the -Y direction, and it is shifted to a position in the -X direction that reflects the number of reflections until it is diffracted by the first pupil enlargement grating layer 51ea. On the other hand, the image light ML propagated in the +X direction in the light guiding member 51a through the incident diffraction layer 51b is diffracted by the second pupil enlargement grating layer 51eb, and its overall optical path is bent in the -Y direction, and it is shifted to a position in the +X direction that reflects the number of reflections until it is diffracted by the second pupil enlargement grating layer 51eb. The first pupil enlargement grating layer 51ea is responsible for an angle of view of, for example, 0° to +20° biased in the -X direction with respect to the Z direction, and the second pupil enlargement grating layer 51eb is responsible for an angle of view of, for example, -20° to 0° biased in the +X direction with respect to the Z direction. The first pupil enlargement grating layer 51ea and the second pupil enlargement grating layer 51eb enlarge the horizontal pupil size. The image light ML propagating through the first pupil enlargement grating layer 51ea in the -Y direction as a whole in the light guiding member 51a is diffracted by the first exit diffraction layer 51ca and is emitted toward the eye EY. On the other hand, the image light ML propagating through the second pupil enlargement grating layer 51eb in the -Y direction as a whole in the light guiding member 51a is diffracted by the second exit diffraction layer 51cb and is emitted toward the eye EY. The first exit diffraction layer 51ca and the second exit diffraction layer 51cb enlarge the vertical pupil size.

[0036] In this embodiment, as in the first embodiment, a stray light suppression filter 51s is disposed on the outside of the emission diffraction layers 51ca and 51cb, that is, on the +Z side. The stray light suppression filter 51s functions as an angle control filter AL and prevents the image light ML from leaking out to the outside.

[0037] [Fourth embodiment] Hereinafter, a virtual image display device according to a fourth embodiment of the present invention will be described. Note that the virtual image display device of the fourth embodiment is a partial modification of the virtual image display device of the first embodiment, and a description of the common parts will be omitted.

[0038] FIG. 6 is a cross-sectional view for explaining the structure of the virtual image display device 110 or the HMD 200 in the fourth embodiment, in which a thin-plate-shaped cover member 40 is disposed on the +Z side, which is the outer side of the diffractive light-guiding member 51. A first stray light suppression filter 41 is attached to a back surface 40i, which is the eye position EP side, of a resin-made base material 40a of the cover member 40. A second stray light suppression filter 42 is attached to a front surface 40o, which is the outside side of the base material 40a. The first stray light suppression filter 41 and the second stray light suppression filter 42 function as an angle control filter AL and prevent the image light ML from leaking out to the outside. If the base material 40a of the cover member 40 is made of resin, the shatterproof effect can be ensured even if the light guide member 51a is made of glass.

[0039] 7, the first stray light suppression filter 41 has a structure similar to that of the stray light suppression filter 51s shown in FIG. +1 The second stray light suppression filter 42 is intended to block the +2nd order diffracted light Ld +2 The purpose is to block light.

[0040] In this embodiment, the second stray light suppression filter 42 provided on the cover member 40 suppresses the high-order +2nd order diffracted light Ld +2 The first stray light suppression filter 41 and the second stray light suppression filter 42 are each adapted to the target diffracted light, and prevent the amount of external light blocked from increasing.

[0041] The second stray light suppression filter 42 may be omitted from the cover member 40. In this case, it is not necessary to attach the first stray light suppression filter 41 to the rear surface 40i, and the first stray light suppression filter 41 may be attached to the front surface 40o.

[0042] 8 is a cross-sectional view illustrating a modified example, in which a first stray light suppression filter 41 and a second stray light suppression filter 42 are attached onto an emission diffraction layer 51c.

[0043] 9 is a cross-sectional view illustrating another modified example. In this case, the incident diffraction layer 51b and the exit diffraction layer 51c are formed on the inner total reflection surface 51i of the light guide member 51a, forming a transmission type diffraction element. The first stray light suppression filter 41 and the second stray light suppression filter 42 are attached on the outer total reflection surface 51o of the light guide member 51a.

[0044] Fifth embodiment Hereinafter, a virtual image display device according to a fifth embodiment of the present invention will be described. Note that the virtual image display device of the fifth embodiment is a partial modification of the virtual image display device of the first embodiment, and a description of the common parts will be omitted.

[0045] FIG. 10 is a cross-sectional view for explaining the structure of the virtual image display device 110 or the HMD 200 in the fifth embodiment. A first stray light suppression filter 41 is attached to the surface 40o of the base material 40a of the cover member 40 arranged outside the diffractive light-guiding member 51, and a wavelength cut filter 44 is attached to the back surface 40i of the cover member 40. The wavelength cut filter 44 is a wavelength limiting filter NF. Specifically, the wavelength cut filter 44 is a notch filter, and prevents diffracted light from being emitted to the outside world side of the exit diffraction layer 51c, which is the second diffraction element DE2. The wavelength limiting filter NF is a filter that limits the passage of diffracted light of a specific wavelength among diffracted light of multiple wavelengths by the exit diffraction layer 51c or the second diffraction element DE2. When the wavelength range of the image light ML emitted from the display panel 11a is wide, the image light ML having a wavelength deviated from the target wavelength of the design of the incident diffraction layer 51b and the exit diffraction layer 51c propagates to the exit diffraction layer 51c via the light guide member 51a and the incident diffraction layer 51b. Therefore, the image light ML having the deviated wavelength may pass through the first stray light suppression filter 41 and be observed from the outside as eye glow. However, by providing the wavelength cut filter 44 on the optical path of the image light ML, the eye glow caused by the image light ML having the deviated wavelength can be suppressed. In other words, the eye glow suppression effect can be enhanced for both diffracted lights having specific wavelengths deviated from the target wavelength.

[0046] Fig. 11 is a cross-sectional view illustrating a modified example. In this case, a wavelength cut filter 14 is provided between the display panel 11a and the collimator lens 11b. This wavelength cut filter 14 has the same function as the wavelength cut filter 44 shown in Fig. 11. In this manner, the wavelength cut filter 44 may be disposed anywhere on the optical path from the display panel 11a, which is the display element, to the light exit side of the exit diffraction layer 51c, which is the second diffraction element DE2.

[0047] Sixth Embodiment Hereinafter, a virtual image display device according to a sixth embodiment of the present invention will be described. Note that the virtual image display device of the sixth embodiment is a partial modification of the virtual image display device of the first embodiment, and a description of the common parts will be omitted.

[0048] In the case of the virtual image display device 110 or the HMD 200 shown in Fig. 12, the third stray light suppression filter 43 is attached on the emission diffraction layer 51c. That is, the third stray light suppression filter 43 is disposed in place of the stray light suppression filter 51s shown in Fig. 2 and the like. The third stray light suppression filter 43 is a wavelength limiting filter NF2 that selectively cuts the RGB wavelength components contained in the image light ML emitted from the display panel 11a. In this case, it is possible to directly and reliably prevent the image light ML from leaking to the outside world.

[0049] [Other matters] The above-described structure is merely an example, and various modifications can be made within the scope of achieving the same function.

[0050] The stray light suppression filter 51s is not limited to one having uniform light blocking characteristics in the XY plane, and may have a distribution of light blocking characteristics in the XY plane. In the above embodiment, the stray light suppression filter 51s is formed in a range that covers the exit diffraction layer 51c, but may also be one that locally covers the exit diffraction layer 51c.

[0051] The stray light suppression filter 51s is not limited to a filter in which the light blocking portions P2 extending linearly are periodically arranged in the light transmitting portion P1, and may be a filter using a diffraction element.

[0052] The first diffraction element DE1 and the second diffraction element DE2 are not limited to those without power, and may be those with power. For example, the first diffraction element DE1 can function as a collimator that couples the image light ML into the light guiding member 51a, and the second diffraction element DE2 can function as an eyepiece that extracts the image light ML propagating in the light guiding member 51a to the eye position EP.

[0053] In the above, the virtual image display device 110 and the like can be used as an HMD, but the present invention is not limited to this and can be applied to various optical devices. For example, the present invention can be applied to a head-up display (HUD).

[0054] In a specific embodiment, the virtual image display device includes a display element that emits image light, a light-guiding member having a first total reflection surface and a second total reflection surface, a first diffraction element on the light incident side associated with the light-guiding member, a second diffraction element on the light exit side associated with the light-guiding member, and a stray light suppression filter that is provided on the external side of the image extraction section on which the second diffraction element is provided and that limits the passage of light diffracted by the second diffraction element.

[0055] In the virtual image display device, since the stray light suppression filter limits the passage of the diffracted light by the second diffraction element, it is possible to prevent the image light emitted forward from the second diffraction element from being observed as eye glow. Also, it is possible to prevent the image light emitted forward from the second diffraction element from being viewed as an image by a person facing the device.

[0056] In a specific aspect, the stray light suppression filter is an angle limiting filter including light blocking portions repeatedly arranged at predetermined intervals in a flat plate. In this case, the thin angle limiting filter can reduce the weight of the stray light suppression filter while increasing the efficiency of blocking diffracted light.

[0057] In a specific aspect, the optical system further includes a filter that limits the passage of diffracted light of a specific wavelength among the diffracted light of multiple wavelengths by the second diffractive element, thereby enhancing the effect of suppressing eye glow for diffracted light of a specific wavelength that is shifted from a target wavelength.

[0058] In a specific aspect, the stray light suppression filter includes a plurality of filters that limit the passage of multiple orders of diffracted light by the second diffractive element, whereby the eye glow suppression effect can be enhanced for all of the multiple orders of diffracted light.

[0059] In a specific aspect, the present invention further includes a flat light transmitting member arranged on the outside world side of the image extraction unit, and the stray light suppression filter is provided on either the outside world side or the eye position side of the light transmitting member. In this case, it is possible to increase the degree of freedom in the arrangement of the stray light suppression filter while maintaining the performance of the stray light suppression filter.

[0060] In a specific aspect, the light transmitting member is made of resin, and the light guiding member is made of glass. The light transmitting member has a role of protecting the light guiding member that can relatively increase the total reflection angle.

[0061] In a specific aspect, the stray light suppression filter is provided on both the outside world side and the eye position side of the light transmitting member.

[0062] In a specific aspect, the first diffractive element and the second diffractive element diffract image light of multiple wavelengths separately, i.e., the first diffractive element and the second diffractive element enable a color display.

[0063] In a specific aspect, the present invention includes a third diffractive element interposed between the first diffractive element and the second diffractive element, for directing the image light in a direction intersecting the diffraction direction of the first diffractive element, and the third diffractive element serves to expand the width of the light beam of the image light incident on the eye in the direction intersecting the diffraction direction of the first diffractive element.

[0064] In a specific aspect, the display device further includes a wavelength limiting filter that is disposed on the optical path from the display element to the light exit side of the second diffraction element and prevents diffracted light from exiting to the outside world side of the second diffraction element. In this case, it is possible to prevent image light of an unintended wavelength from being emitted forward from the second diffraction element and being observed as eye glow.

[0065] The stray light suppression filter is a wavelength limiting filter that prevents image light from being emitted to the outside world side of the second diffraction element.

[0066] In a specific embodiment, the optical unit includes a display element that emits image light, a light-guiding member having a first total reflection surface and a second total reflection surface, a first diffraction element on the light incident side associated with the light-guiding member, a second diffraction element on the light exit side associated with the light-guiding member, and a stray light suppression filter that is provided on the external side of the image extraction section on which the second diffraction element is provided and that limits the passage of light diffracted by the second diffraction element.

[0067] 10...projection device, 11...image light generating device, 11a...display panel, 14, 44...wavelength cut filter, 40...cover member, 50...light guiding optical system, 51...diffractive light guiding member, 51a...light guiding member, 51b...entrance diffraction layer, 51c...exit diffraction layer, 51e...pupil enlargement grating layer, 51i, 51o...total reflection surface, 51s...stray light suppression filter, 51t...light shielding layer, 60...drive circuit, 91...cover, 110, 110A, 110B...virtual image display device, AL...angle control filter, EP...eye position, ES...exit surface, EY...eye, GL...display light, II...image capture unit, IO...image extraction unit, IS...entrance surface, ML...image light, NF...wavelength limiting filter, OL...external light, OU...optical unit, US...wearer

Claims

1. a display element that emits image light; an incident area into which the image light is incident and an exit area having an exit surface from which the image light is exited; a light guide member having a first diffraction element provided in the incident area and configured to diffract the image light; the first diffraction element is provided on the opposite side of the exit surface in the exit region, a second diffraction element that diffracts at least a portion of the refracted image light toward the exit surface; a light emitting element provided in the light emitting region of the light guiding member, the light emitting element being a light emitting element for guiding the image light passing through the second diffraction element; a stray light suppression filter for limiting the amount of light passing through the optical fiber; The second diffraction element is disposed between the exit surface and the stray light filter in the exit region. A virtual image display device provided in.

2. The stray light suppression filter is an angle filter including light-shielding portions repeatedly arranged at predetermined intervals in a flat plate. The virtual image display device of claim 1 , further comprising a restriction filter.

3. The stray light suppression filter is configured to filter out a plurality of wavelengths contained in the image light passing through the second diffraction element.

2. The virtual image display device according to claim 1, further comprising a filter that limits the passage of light of a specific wavelength. Place.

4. The stray light suppression filter is configured to suppress a plurality of orders of the image light passing through the second diffraction element. The virtual image display device according to claim 1 , further comprising a plurality of filters that limit the passage of diffracted light.

5. Further comprising a flat light-transmitting member provided in the emission region, The second diffraction element is provided between the exit surface and the light transmitting member in the exit region. Knocked off, The stray light suppression filter is disposed on at least one of the external environment side and the eye position side of the light transmitting member. The virtual image display device according to claim 1 , wherein the virtual image display device is provided on the front surface of the display panel.

6. the light transmitting member is made of resin, The virtual image display device according to claim 5 , wherein the light guide member is made of glass.

7. The stray light suppression filter is provided on both the outside world side and the eye position side of the light transmitting member. The virtual image display device according to claim 5 .

8. the first diffraction element and the second diffraction element diffract image light of multiple wavelengths individually. Item 2. The virtual image display device according to item 1.

9. A diffraction element is interposed between the first diffraction element and the second diffraction element, and a diffraction direction of the first diffraction element is 2. The virtual image display device according to claim 1, further comprising a third diffraction element for directing the image light in a direction intersecting the direction of the first diffraction element. Place.

10. The stray light suppression filter is configured to emit the image light to the outside of the second diffraction element.

2. The virtual image display device according to claim 1, wherein the wavelength limiting filter is a wavelength limiting filter that prevents

11. a display element that emits image light; an incident area into which the image light is incident and an exit area having an exit surface from which the image light is exited; a light guide member having a first diffraction element provided in the incident area and configured to diffract the image light; the first diffraction element is provided on the opposite side of the exit surface in the exit region, a second diffraction element that diffracts at least a portion of the refracted image light toward the exit surface; a light emitting element provided in the light emitting region of the light guiding member, the light emitting element being a light emitting element for guiding the image light passing through the second diffraction element; a stray light suppression filter for limiting the amount of light passing through the optical fiber; The second diffraction element is disposed between the exit surface and the stray light filter in the exit region. An optical unit provided in the

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