Virtual image display device and optical unit

Abstract

To address luminance unevenness in which a contrast difference with respect to a visual angle when viewing images with a virtual image display device.SOLUTION: A virtual image display device includes: a display panel that emits image light; a projection optical system that collimates the image light from the display panel; a light guide plate that guides the image light; an incident diffraction optical system that makes the image light from the projection optical system incident on the light guide plate; and an emission diffraction optical system that emits the image light from the light guide plate. The display panel includes a first partial display region and a second partial display region arranged with the center point of the display panel held therebetween. The image light emitted from the display panel includes first partial image light emitted from the first partial display region and second partial image light emitted from the second partial display region. Among incident surfaces of the incident diffraction optical system, a first incident area where the first partial image light enters is smaller than a second incident area where the second partial image light enters.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a virtual image display device and an optical unit that enable viewing of a virtual image. [Background technology]

[0002] The optical device includes a first light guide, a second light guide, a first diffractive optical element, and a second diffractive optical element, the first light guide having a first light entrance portion and a first light exit portion, the second light guide having a second light entrance portion and a second light exit portion, the first diffractive optical element is provided at the second light exit portion of the second light guide and diffracts at least a portion of the light guided inside the second light guide to extract it to the outside of the second light guide, the second diffractive optical element is provided at the first light exit portion of the first light guide and diffracts at least a portion of the light guided inside the first light guide and extracted by the first diffractive optical element. At least a portion of the light incident on the first light guide and the second light guide is extracted, a portion of the incident light entering the first light guide from the first light entrance portion and guided therein, and another portion of the incident light entering the second light guide from the second light entrance portion and guided therein, the light guided inside the second light guide contains more light with longer wavelengths than the light guided inside the first light guide, the second diffractive optical element includes portions having different diffraction efficiency between a side closer to the first light entrance portion and a side farther from the first light entrance portion, and it is publicly known that the first diffractive optical element has an approximately constant diffraction efficiency (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-049376 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the optical device shown in Patent Document 1, the entire field angle of the image light is incident on each input grating, so the diffraction efficiency changes for each field angle. In other words, it is not possible to deal with the brightness unevenness that occurs when viewing an image with respect to the field angle. [Means for solving the problem]

[0005] A virtual image display device and optical unit in one aspect of the present invention comprises a display panel that emits image light, a projection optical system that collimates the image light from the display panel, a light guide plate that guides the image light, an incident diffraction optical system that causes the image light from the projection optical system to be incident on the light guide plate, and an exit diffraction optical system that emits the image light from the light guide plate, wherein the display panel includes a first display area and a second partial display area that is arranged in a first direction in which the wearer's eyes are aligned as viewed from the first partial display area and has the same area and shape as the first partial display area, wherein the image light emitted from the display panel includes a first partial image light emitted from the first display area and a second partial image light emitted from the second partial display area, and a first entrance area of ​​the entrance surface of the entrance diffraction optical system into which the first partial image light is incident is smaller than a second entrance area into which the second partial image light is incident. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a diagram illustrating a state in which the HMD according to the first embodiment is worn. [Diagram 2] FIG. 2 is a side view for explaining the arrangement of an optical system that constitutes the virtual image display device. [Diagram 3] FIG. 2 is a plan view for explaining the arrangement of an optical system that constitutes the virtual image display device. [Figure 4] FIG. 4 is a partial perspective rear view illustrating a light-guiding optical system or a light-guiding member. [Diagram 5] FIG. 2 is a plan view illustrating an optical system. [Figure 6] FIG. 11 is a plan view illustrating the occurrence of luminance unevenness. [Figure 7] FIG. 2 is a plan view for explaining the arrangement of an incident diffraction layer and an optical system. [Figure 8]FIG. 4 is a side view illustrating the emission direction of light emitted from the display panel. [Figure 9] FIG. 11 is a side view illustrating a change in the light emission direction using a microlens. [Figure 10] 1 is a side view illustrating light incident on an incident diffraction layer from a projection optical system. FIG. [Figure 11] FIG. 2 is a plan view for explaining the arrangement of an incident diffraction layer and an optical system. [Figure 12] 1 is a side view illustrating light incident on an incident diffraction layer from a projection optical system. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] [First embodiment] Hereinafter, a first embodiment of virtual image display devices 100A and 100B according to the present invention will be described with reference to FIGS.

[0008] Fig. 1 is a diagram for explaining the wearing state of a head mounted display device (hereinafter also referred to as a head mounted display or HMD) 200, in which the observer or wearer US wearing the HMD 200 recognizes an image as a virtual image. In Fig. 1 etc., X, Y, and Z are an orthogonal coordinate system, the +X direction corresponds to the lateral direction in which the eyes EY of the observer or wearer US wearing the HMD 200 are aligned, the +Y direction corresponds to the upward direction perpendicular to the lateral direction in which the 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 first virtual image display device 100A for the left eye, a second virtual image display device 100B for the right eye, a pair of temple-shaped support devices 100C for supporting the virtual image display devices 100A and 100B, and a user terminal 90 that is an information terminal. The first virtual image display device 100A functions as an HMD by itself, and is composed of a first display drive unit 102a arranged at the top, and a first light guide optical system 103a that is shaped like a pair of glasses and covers the front of the eyes. The second virtual image display device 100B also functions as an HMD by itself, and is composed of a second display drive unit 102b arranged at the top, and a second light guide optical system 103b that is shaped like a pair of glasses and covers the front of the eyes. The support device 100C is a mounting member that is mounted on the head of the wearer US, and supports the upper end sides of the pair of light guide optical systems 103a and 103b via the display drive units 102a and 102b that are integrated in appearance. The first virtual image display device 100A and the second virtual image display device 100B are optically reversed from left to right, and a detailed description of the second virtual image display device 100B will be omitted.

[0010] Fig. 2 is a side view specifically explaining the first display driving unit 102a and the first light guiding optical system 103a of the first virtual image display device 100A. Fig. 3 is a plan view specifically explaining the first display driving unit 102a and the first light guiding optical system 103a. Fig. 4 is a rear view mainly explaining the first light guiding optical system 103a.

[0011] 2 and 3, the first display driving unit 102a includes an image light generating device 10, a projection optical system 20, and a driving circuit member 88. The image light generating device 10 is an optical engine including a display panel 11a. The projection optical system 20 is a collimator including a plurality of lens elements 21. The image light ML generated by the image light generating device 10 is collimated by the projection optical system 20 and coupled to the first light guiding optical system 103a, which is the light guiding member 50. The driving circuit member 88 causes the display panel 11a to perform a display operation. In the first virtual image display device 100A, an optical device excluding the driving circuit member 88 is called an optical unit 100. The first virtual image display device 100A guides the image light ML to the eye EY of the wearer US, thereby allowing the wearer US to view a virtual image.

[0012] 4, the first light guiding optical system 103a is a light guiding member 50 that enables color display and extends approximately parallel to the XY plane. The first light guiding optical system 103a has a light guiding plate 51a, an incident diffraction layer 51b, a pupil enlargement grating layer 51e, and an exit diffraction layer 51c. The incident diffraction layer 51b, the exit diffraction layer 51c, and the pupil enlargement grating layer 51e diffract light in accordance with the wavelength of the image light ML. The incident diffraction layer 51b guides the collimated image light ML from the first display driving unit 102a into the light guide plate 51a and propagates it laterally, the pupil enlargement lattice layer 51e propagates the image light ML propagating laterally within the light guide plate 51a downward while expanding the pupil size of the image light ML, and the exit diffraction layer 51c exits the image light ML toward a pupil position PP (see Figure 2) set inside where the eye EY (see Figure 2) is located, while expanding the pupil size of the image light ML propagating downward within the light guide plate 51a.

[0013] FIG. 5 is a diagram for explaining the optical system of the first display driving unit 102a. In the first display driving unit 102a, the image light generating device 10 includes only one display panel 11a. That is, the display panel 11a includes pixels of three colors, RGB, and the pixels of each color are arranged two-dimensionally in the display panel 11a. The projection optical system 20 includes a plurality of lens elements 21. The display panel 11a and the projection optical system 20 are fixed in a state in which they are positioned relative to each other by a lens barrel 30. As shown in FIG. 2, the lens barrel 30 is supported together with the driving circuit member 88 by a holder 71 that also serves as a cover in a state in which they are positioned relative to each other, and is fixed to the first light guiding optical system 103a.

[0014] 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. Specifically, the display panel 11a is a display of various light-emitting element arrays such as OLED (Organic Light Emitting Diode), organic EL (Organic Electro-Luminescence), inorganic EL, and LED, and forms still images or moving images on a two-dimensional display surface parallel to the XY plane. The display panel 11a has a light-emitting element 14a. The light-emitting element 14a is a multiplicity of pixels two-dimensionally arranged on a substrate along the XY plane. When the display panel 11a is an OLED display, each pixel constituting the light-emitting element 14a includes, in order from the substrate side, a cathode, an electron transport layer, a light-emitting layer, a hole transport layer, and a transparent electrode layer.

[0015] 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 background. Instead of an LCD, LCOS (Liquid crystal on silicon, LCoS is a registered trademark), a digital micromirror device, or the like may be used as the display panel 11a.

[0016] The projection optical system 20 includes a first lens 21a and a second lens 21b as lens elements 21 that collimate, i.e., parallelize, the incident light. The projection optical system 20 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 light guide member 50 in an inclination angle state according to the pixel position. The projection optical system 20 may include optical elements such as a reflecting mirror in addition to one or more lens elements made of resin or glass. The optical surfaces of the optical elements constituting the projection optical system 20 may be any of spherical, aspherical, and free-form surfaces. Hereinafter, the light emitted from the different light-emitting elements 14a of the image light ML may be referred to as partial image light ML0, ML1, and ML2, respectively.

[0017] Returning to Fig. 4, in the first light guiding optical system 103a or the light guiding member 50, the incident diffraction layer 51b is an input diffractive optical element DI, 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 an output diffractive optical element DO, 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 pupil enlargement diffractive optical element DE, 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 plate 51a and travels in the -X direction as a whole, so that it travels in the -Y direction as a whole.

[0018] The light guide plate 51a is a member formed from a parallel plate, and has an inner total reflection surface 51i and an outer total reflection surface 51o that are a pair of flat surfaces extending parallel to the XY plane (see FIG. 2).

[0019] The entrance diffraction layer 51b, the exit diffraction layer 51c, and the pupil enlargement grating layer 51e are formed on an inner total reflection surface 51i of the light guide plate 51a.

[0020] The incident diffraction layer 51b, the exit diffraction layer 51c, and the pupil enlargement grating layer 51e diffract light in accordance with the wavelength of the image light ML, and are formed, for example, of a surface relief type diffraction element. The surface relief type diffraction element is formed by nanoimprinting, but is not limited to this, and can also be formed by etching the surface of the light guide plate 51a, or a diffraction element may be attached.

[0021] The pupil enlargement grating layer 51e does not substantially impair the angular information of the image light ML in the left-right X direction or the vertical Y direction while switching the diffraction direction. The pupil enlargement grating layer 51e, i.e., the pupil enlargement diffractive optical element DE, guides the image light ML guided into the light guide plate 51a from the input diffractive optical element DI, which is the incident diffraction layer 51b, to the output diffractive optical element DO, which is the exit diffraction layer 51c, while enlarging the pupil of the exit diffraction layer 51c. More specifically, the pupil enlargement grating layer 51e is interposed between the incident diffraction layer 51b and the exit diffraction layer 51c, and divides the light beam while guiding the image light ML in a direction (-Y direction) intersecting the diffraction direction (-X direction) of the incident diffraction layer 51b, and has a role of expanding the light beam width in the horizontal direction. The pupil enlargement grating layer 51e is formed by a diffraction pattern that extends linearly in the oblique DS2 direction parallel to the XY plane and is periodically repeated in the DS1 direction parallel to the XY plane and perpendicular to the DS2 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 the Y direction of the pattern formed on the pupil enlargement grating layer 51e is consistent with the grating period in the X direction of the pattern formed on the entrance diffraction layer 51b, and is consistent with the grating period in the Y direction of the pattern formed on the exit diffraction layer 51c. The exit diffraction layer 51c divides the light beam while guiding the image light ML in the -Y direction, and has a role of expanding the light beam width in the vertical direction. As a result, the light beam width in the X direction and the Y direction of the image light ML incident on the pupil position PP shown in FIG. 2 has a spread corresponding to the exit diffraction layer 51c, and the pupil size in the vertical direction and the horizontal direction increases through the pupil enlargement grating layer 51e, the exit diffraction layer 51c, etc. The image light ML collimated around the exit optical axis OX (see FIG. 2) perpendicular to the light guide plate 51a is emitted from the exit diffraction layer 51c.

[0022] With reference to Fig. 6, the occurrence of luminance unevenness in the image light ML guided from the incident diffraction layer 51b to the exit diffraction layer 51c inside the light guide plate 51a will be described. Fig. 6 is a plan view that shows a schematic positional relationship in the XZ direction among the image light generating device 10, the lens element 21 as the projection optical system 20, the incident diffraction layer 51b, the light guide plate 51a, the exit diffraction layer 51c, the wearer's eye EY, and the image light ML. However, in Fig. 6, in order to simplify the explanation, the pupil enlargement grating layer 51e that changes the propagation direction of the image light ML on the way from the incident diffraction layer 51b to the exit diffraction layer 51c is omitted, and the dimensions of each component are shown exaggerated.

[0023] As shown in Figure 6, the image light ML from the projection optical system 20 is diffracted by the incident diffraction layer 51b and enters the light guide plate 51a, is guided along the light guide plate 51a while being totally reflected by the outer total reflection surface 51o and the inner total reflection surface 51i of the light guide plate 51a, is diffracted by the exit diffraction layer 51c, and is emitted toward the eye EY.

[0024] Here, the image light ML includes a first partial image light ML1 and a second partial image light ML2. The first partial image light ML1 and the second partial image light ML2 are emitted from the first partial display area 111 and the second partial display area 112 shown in FIG. 5 of the display panel 11a. The first partial display area 111 is arranged in a direction (−X direction in FIG. 6) of a component parallel to a first direction (±X direction) in which both eyes EY of the wearer are aligned, from the direction from the incident diffraction layer 51b to the exit diffraction layer 51c, as viewed from the center point 11c of the display panel 11a. The second partial display area 112 is arranged in a direction opposite to the first partial display area 111, as viewed from the center point 11c (+X direction in FIG. 6). Note that, as shown in FIG. 5 and the area ER1 in FIG. 6, a virtual straight line AX1 that is perpendicular to the display surface 11d of the display panel 11a and passes through the center point 11c passes through the center point 510 of the incident diffraction layer 51b. The first direction (±X direction) is the direction in which multiple convex portions included in the diffraction pattern that constitutes the incident diffraction layer 51b are periodically arranged, and is also the direction in which the image light ML incident from the incident diffraction layer 51b to the light guide plate 51a is guided toward the pupil enlargement grating layer 51e.

[0025] Hereinafter, in order to make it easier to compare the first partial image light ML1 and the second partial image light ML2, a case will be described in which the areas of the first partial display region 111 and the second partial display region 112 are the same and the distances from the center point 11c to the first partial display region 111 and the second partial display region 112 are the same. Here, the center point 11c may be a point on the display surface 11d of the display panel 11a where the optical axis AX1 of the projection optical system 20 intersects, or may be a geometric center defined as an intersection point of diagonal lines connecting vertices of the display panel 11a or a center of gravity determined based on the shape of the display panel 11a, or may be a point included in the display surface 11d of the display panel 11a and separated from the geometric center by an arbitrary distance in a direction (±Y direction) perpendicular to the first direction (±X direction).

[0026] Focusing on each of the multiple convex portions included in the incident diffraction layer 51b, when two partial image lights ML1 and ML2 emitted from two different display areas 111 and 112 included in the same display panel 11a are diffracted by the same convex portion of the diffraction pattern constituting the incident diffraction layer 51b and enter the light guide plate 51a, the incident angles of the partial image lights ML1 and ML2 to the incident diffraction layer 51b are different. When the incident angles of the two partial image lights ML1 and ML2 to the incident diffraction layer 51b are different from each other, the incident angles AI1 and AI2 at which the partial image lights ML1 and ML2 are totally reflected inside the light guide plate 51a are different from each other, and therefore the reflection angles AR1 and AR2 are also different from each other. In other words, the incident angle and reflection angle at which the light is totally reflected inside the light guide plate 51a are different depending on the angle of view of the light included in the image light ML incident on the incident diffraction layer 51b.

[0027] Specifically, as shown in the example of Figure 6, the first incident angle AI1 and first reflection angle AR1 when the first partial image light ML1 incident on the incident diffraction layer 51b from a direction closer to the exit diffraction layer 51c is totally reflected by the outer total reflection surface 51o and the inner total reflection surface 51i are smaller than the second incident angle AI2 and second reflection angle AR2 when the second partial image light ML2 incident on the incident diffraction layer 51b from a direction farther away from the exit diffraction layer 51c is totally reflected by the outer total reflection surface 51o and the inner total reflection surface 51i.

[0028] When the partial image light ML1, ML2 are repeatedly totally reflected inside the light guide plate 51a at different angles of incidence and reflection, the number of times the partial image light ML1, ML2 are totally reflected per unit length in the extending direction of the light guide plate 51a is also different. When the number of times the partial image light ML1, ML2 are totally reflected per unit length of the light guide plate 51a is different, the total number of convex portions that diffract the partial image light ML1, ML2 when it is emitted to the outside of the light guide plate 51a among the diffraction patterns that constitute the same exit diffraction layer 51c is also different. In other words, depending on the angle of view of the light contained in the image light ML that enters the entrance diffraction layer 51b, the angle of incidence and the angle of reflection when the light is totally reflected inside the light guide plate 51a are different, and the total number of convex portions of the exit diffraction layer 51c that diffract the image light ML when it is emitted to the outside from the light guide plate 51a is also different.

[0029] Specifically, as shown in the example of Figure 6, the total number of convex portions in the exit diffraction layer 51c that diffract the first partial image light ML1 having the smaller first incident angle AI1 and first reflection angle AR1 when it is emitted outside the light guide plate 51a is greater than the total number of convex portions that diffract the second partial image light ML2 having the larger second incident angle AI2 and second reflection angle AR2 when it is emitted outside the light guide plate 51a.

[0030] When the image light ML is emitted from the light guide plate 51a, the greater the total number of convex portions in the emission diffraction layer 51c that diffract the light of a predetermined angle of view contained in the image light ML, the greater the amount of the emitted light and the higher the luminance of the emitted image light ML. As a result, the luminance of the image light ML has a different distribution depending on the angle of view of the light contained in the image light ML that enters the entrance diffraction layer 51b. In other words, when viewed from the eye EY of the wearer US, luminance unevenness may occur depending on the angle of view of the image light ML.

[0031] In this embodiment, as one method for reducing the brightness unevenness as described above, the positional relationship between the projection optical system 20 and the incident diffraction layer 51b is appropriately set so that, when the image light ML from the projection optical system 20 is incident on the light guide plate 51a, the total number of convex parts that diffract the light contained in the image light ML in the diffraction pattern that constitutes the incident diffraction layer 51b varies for each angle of view of the light. Here, the total number of convex parts that diffract the light contained in the image light ML is proportional to the incident area, into which the light is incident, of the incident surface of the incident diffraction layer 51b.

[0032] Specifically, as shown in region ER2 of Figure 7, the position of the projection optical system 20 with respect to the incident diffraction layer 51b is set so that the optical axis AX1 of the projection optical system 20 is shifted a predetermined distance D from the center of the incident diffraction layer 51b in a direction (-X direction) that is a directional component parallel to the first direction (±X direction) of the direction from the incident diffraction layer 51b to the exit diffraction layer 51c.

[0033] As a result, when the light contained in the image light ML from the projection optical system 20 is diffracted by the incident diffraction layer 51b and enters the light guide plate 51a, the total number of convex portions that diffract the light in the diffraction pattern that constitutes the incident diffraction layer 51b changes according to the angle of view of the light in the image light ML. The more external convex portions that diffract the light, the wider the beam width of the light guided inside the light guide plate 51a. In other words, the beam widths W1 and W2 in the first direction (±X direction) of the partial image lights ML1 and ML2 contained in the image light ML from the projection optical system 20 change according to the angle of view of the light.

[0034] 7, when the first partial image light ML1 and the second partial image light ML2 contained in the image light ML are compared, the total number of convex portions that diffract the second partial image light ML2 is greater than the total number of convex portions that diffract the first partial image light ML1 in the diffraction pattern that constitutes the incident diffraction layer 51b. As a result, inside the light guide plate 51a, the luminous flux width W2 of the second partial image light ML2 is wider than the luminous flux width W1 of the first partial image light ML1.

[0035] Thereafter, as described with reference to Fig. 6, when the first partial image light ML1 and the second partial image light ML2 are emitted from the light guide plate 51a, the total number of convex portions diffracting the second partial image light ML2 is greater than the total number of convex portions diffracting the first partial image light ML1 in the diffraction pattern constituting the emission diffraction layer 51c. In other words, the difference in luminance between the first partial image light ML1 having a narrower light flux width W1 and diffracted by more convex portions for emission and the second partial image light ML2 having a wider light flux width W2 and diffracted by fewer convex portions for emission is smaller than that in the configuration of Fig. 5. As a result, the luminance unevenness of the image light ML in the eye EY of the wearer US is reduced.

[0036] Second Embodiment In the above-described first embodiment, a configuration was described in which the positional relationship between the projection optical system 20 and the incident diffraction layer 51b is appropriately set to change the beam width of the light contained in the image light ML according to the angle of view of the light in order to reduce the luminance unevenness that occurs in the light contained in the image light ML according to the angle of view of the light. In the present embodiment, as another method for reducing the above-described luminance unevenness, the direction in which the projection optical system 20 emits the light contained in the image light ML is changed according to the angle of view of the light.

[0037] Specifically, first, as shown in Fig. 8, directions D0, D1, D2 in which the display panel 11a emits the light contained in the image light ML are changed according to the position in the first direction (±X direction) of partial display areas 110, 111, 112 included in the display panel 11a. More specifically, the surface of the display panel 11a is divided and managed into a plurality of partial display areas 110, 111, 112, and one of the partial display areas 110, 111, 112 is set as a reference display area 110 that serves as a reference in the first direction (±X direction). The direction in which the light of the image light ML is emitted from the reference display area 110 is set as a reference emission direction D0. As an example, the reference emission direction D0 may be a direction perpendicular to the display surface 11d of the display panel 11a (+Z direction). In a first direction (±X direction), a first partial display area 111 arranged in a first shift direction (-X direction) from the incident diffraction layer 51b to the exit diffraction layer 51c as viewed from the reference display area 110 tilts the direction D1 in which the image light ML is emitted by a predetermined first tilt angle AT1 in a rotational direction approaching the reference display area 110 from the reference emission direction (+Z direction) within a virtual plane (XZ plane) including the first direction (±X direction) and the reference emission direction (+Z direction). In addition, in the first direction (±X direction), the direction in which the second partial display area 112 arranged in the second shift direction (+X direction) from the exit diffraction layer 51c toward the entrance diffraction layer 51b as viewed from the reference display area 110 emits the light of the image light ML is tilted by a predetermined second tilt angle AT2 in a rotation direction away from the reference emission direction from the reference display area 110 within a virtual plane (XZ plane) including the first direction (±X direction) and the reference emission direction (+Z direction). At this time, the first incident angle at which the first partial image light ML1 from the first lens 21a is incident on the second lens 21b is smaller than the second incident angle at which the second partial image light ML2 from the first lens 21a is incident on the second lens 21b. FIG. 8 shows the intensity distributions PD0, PD1, and PD2 of the light emitted from the reference display area 110, the first partial display area 111, and the second partial display area 112, respectively, of the image light ML.

[0038] At this time, the positions of the microlenses included in the microlens array as the first lenses 21a arranged corresponding to the reference display area 110 and the partial display areas 111 and 112 can be shifted by a predetermined distance in the first direction from a reference position, so that the direction in which each of the partial display areas 110, 111 and 112 emits the image light ML can be tilted. Here, the microlens array is an optical element configured by arranging microlenses in an array so as to face each of the reference display area 110 and the partial display areas 111 and 112 as pixels or a set of pixels included in the display panel 11a. In other words, the microlens array functions as an emission direction changing optical system that changes the emission direction of light emitted from each of the multiple pixels included in the display panel 11a based on the positions of each of the multiple pixels on the display panel 11a. Each microlens, together with a second lens 21b arranged behind a first lens 21a as a microlens array, is configured to collimate light emitted from a corresponding pixel or the reference display area 110 and the partial display areas 111, 112.

[0039] Specifically, as shown in FIG. 9, the microlens 210 corresponding to the reference display area 110 is disposed in front of the reference display area 110, the microlens 211 corresponding to the first partial display area 111 is shifted a predetermined first shift distance DS1 from the front of the first partial display area 111 in the first shift direction (-X direction), and the microlens 212 corresponding to the second partial display area 112 is shifted a predetermined shift distance DS2 from the front of the second partial display area 112 in the second shift direction (+X direction). As a result, of the image light ML, the light emitted from the reference display area 110 is emitted by the microlens 210 in the reference emission direction D0 (+Z direction) as the 0th partial image light ML0, the light emitted from the first partial display area 111 is emitted by the microlens 211 in a direction D1 tilted by the first tilt angle AT1 from the reference emission direction (+Z direction) as the first partial image light ML1, and the light emitted from the second partial display area 112 is emitted by the microlens 212 in a direction D2 tilted by the second tilt angle AT2 from the reference emission direction (+Z direction) as the second partial image light ML2.

[0040] 10, the partial image light ML1, ML2 emitted from the partial display areas 111, 112 in different emission directions of the image light ML are collimated by passing through the second lens 21b of the projection optical system 20, diffracted by the incident diffraction layer 51b, and enter the light guide plate 51a. At this time, the incident angles of the partial image light ML1, ML2 when they reach the incident diffraction layer 51b are tilted by different tilt angles AT1, AT2 by the first lens 21a as a microlens array, so that the total numbers of convex portions that diffract the partial image light ML1, ML2 in the diffraction patterns that constitute the incident diffraction layer 51b are different from each other. As a result, by appropriately setting the first tilt angles AT1, AT2 or the first shift distance DS1 and the second shift distance DS2, it is possible to reduce the luminance unevenness as in the embodiment, compared to the case where the partial image light ML1, ML2 are emitted in the reference emission direction.

[0041] (Variation: More partial display areas) In the above second embodiment, a configuration has been described in which the display panel 11a is divided and managed into the reference display area 110, the first partial display area 111, and the second partial display area 112, and the light of the image light ML emitted from each of these three areas is emitted in a different direction. As a variation of this configuration, the display panel 11a may be divided and managed into more partial display areas, and the first lens 21a may be configured as a microlens array so that the light of the image light ML emitted from each of the partial display areas is emitted in a different direction.

[0042] (Variation: Color filter shift) As a further modification of the above configuration, a color filter array may be used instead of the microlens array. The color filter array is configured by arranging color filters in an array to provide color information of R (red), G (green), and B (blue) components to three sub-pixels provided in each of the pixels of the display panel 11a. That is, in this modification, the display panel 11a includes a single-plate RGB panel including a plurality of sub-pixels that individually emit light of the R, G, and B components of the image light ML for each of the pixels. The sub-pixels may be arranged on a single panel, but this is merely an example and does not limit the present disclosure. In this modification, instead of arranging each color filter in front of the corresponding sub-pixel, the color filters are arranged shifted by a predetermined shift distance in the first shift direction or the second shift direction according to the position of the sub-pixel in the display panel 11a, thereby appropriately changing the emission direction of the light emitted by each sub-pixel in the image light ML, and the luminance unevenness can be reduced as in the case of the second embodiment.

[0043] (Variation: 3 display panels) In the above second embodiment, a configuration has been described in which a microlens array is used as the first lens 21a, and a plurality of microlenses included in the microlens array are arranged corresponding to a plurality of pixels or a plurality of partial display areas 111, 112 included in the display panel 11a. As a modified example of this configuration, the display panel 11a that emits the image light ML may be replaced with three display panels that respectively emit components of the three primary colors. In this case, each of the three display panels may be provided with a microlens array having the same configuration. In addition, a synthesis optical system that synthesizes the three color components that make up the image light ML may be further provided between the three microlens arrays and the emission diffraction layer 51c.

[0044] Third Embodiment In the above-described first embodiment, a configuration has been described in which the position of the optical axis AX1 of the projection optical system 20 relative to the center of the incident diffraction layer 51b is shifted in a first shift direction (-X direction) from the incident diffraction layer 51b to the exit diffraction layer 51c in order to reduce luminance unevenness of the image light ML in the eye EY of the wearer US. As a modified example of this configuration, a description will be given of a case in which the position of the optical axis AX1 of the projection optical system 20 relative to the center of the incident diffraction layer 51b is shifted in a second shift direction (+X direction) from the exit diffraction layer 51c to the incident diffraction layer 51b in the opposite direction to the first embodiment, that is, in a second shift direction (+X direction) from the exit diffraction layer 51c to the incident diffraction layer 51b, which can also reduce luminance unevenness of the image light ML in the eye EY of the wearer US.

[0045] FIG. 11 is a diagram showing a modified position of the projection optical system 20 relative to the incident diffraction layer 51b in FIG. 5 for explaining the optical system of the first display driver 102a according to the first embodiment. As shown in the region ER3 in FIG. 11, in this embodiment, the projection optical system 20 is shifted by an appropriate distance D in the second shift direction (+X direction) as viewed from the center of the incident diffraction layer 51b. At this time, the first partial image light ML1 is diffracted by the incident diffraction layer 51b and enters the light guide plate 51a, is totally reflected once by the outer total reflection surface 51o of the light guide plate 51a, and reaches the end of the incident diffraction layer 51b on the second shift direction side when totally reflected by the inner total reflection surface 51i of the light guide plate 51a. When such a condition is satisfied, the total number of convex parts that diffract the second partial image light ML2 in the diffraction pattern that constitutes the incident diffraction layer 51b is greater than the total number of convex parts that diffract the first partial image light ML1. As a result, as in the first embodiment, the luminous flux width of the second partial image light ML2 of the image light ML guided inside the light guide plate 51a becomes wider than the luminous flux width of the first partial image light ML1, thereby reducing brightness unevenness in the image light ML emitted from the light guide plate 51a.

[0046] In this embodiment, similarly to the first embodiment, the first partial image light ML1 is emitted from a first partial display region 111 of the display panel 11a located in a first shift direction (-X direction) as viewed from the center point 11c of the display panel 11a, as shown in Fig. 5 etc. The second partial image light ML2 is emitted from a second partial display region 112 of the display panel 11a located in a second shift direction (+X direction) as viewed from the center point 11c of the display panel 11a, as shown in Fig. 5 etc.

[0047] [Fourth embodiment] In the above-described second embodiment, a configuration has been described in which, in order to reduce luminance unevenness of the image light ML at the eye EY of the wearer US, the direction in which the first partial image light ML1 of the image light ML emitted by the projection optical system 20 is emitted is tilted in a rotational direction from the reference emission direction (+Z direction) toward the reference display area 110, and the direction in which the second partial image light ML2 is emitted is tilted in a rotational direction from the reference emission direction (+Z direction) away from the reference display area 110. As a modified example of this configuration, a description will be given of the fact that luminance unevenness of the image light ML at the eye EY of the wearer US can be reduced even when the emission directions of the first partial image light ML1 and the second partial image light ML2 are each tilted in a rotational direction opposite to that of the second embodiment.

[0048] Fig. 12 is an example in which the emission directions of the partial image light ML1, ML2 are changed from Fig. 10 for explaining the partial image light ML1, ML2 according to the second embodiment. As shown in Fig. 12, in this embodiment, the emission direction of the first partial image light ML1 is tilted from the reference emission direction (+Z direction) to a rotation direction moving away from the reference display area 110, and the emission direction of the second partial image light ML2 is tilted from the reference emission direction (+Z direction) to a rotation direction moving closer to the reference display area 110. At this time, a first incidence angle at which the first partial image light ML1 from the first lens 21a is incident on the second lens 21b is larger than a second incidence angle at which the second partial image light ML2 from the first lens 21a is incident on the second lens 21b. 10, if the shape and position of the second lens 21b are appropriately changed, the total number of convex portions that diffract the second partial image light ML2 in the diffraction pattern that constitutes the incident diffraction layer 51b becomes greater than the total number of convex portions that diffract the first partial image light ML1. As a result, as in the second embodiment, the luminous flux width of the second partial image light ML2 in the image light ML guided inside the light guide plate 51a becomes wider than the luminous flux width of the first partial image light ML1, and the luminance unevenness of the image light ML output from the light guide plate 51a is reduced.

[0049] In the present embodiment, similarly to the second embodiment, the first partial image light ML1 is emitted from the first partial display area 111 of the display panel 11a, which is located in the first shift direction (-X direction) as viewed from the center point 11c of the display panel 11a, as shown in Fig. 5 and other figures. The second partial image light ML2 is emitted from the second partial display area 112 of the display panel 11a, which is located in the second shift direction (+X direction) as viewed from the center point 11c of the display panel 11a, as shown in Fig. 5 and other figures. However, in the present embodiment, the microlenses 211 and 212 shown in Fig. 9 are shifted from the centers of the partial display areas 111 and 112 in the first shift direction (-X direction), so that the direction in which the partial image light ML1 and ML2 are emitted is opposite to the rotation direction in the second embodiment.

[0050] In the above, the virtual image display devices 100A, 100B can be used as HMDs, 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).

[0051] In addition, the modified examples described above can be combined with each other to the extent that there is no technical contradiction. For example, the configurations of the first embodiment and the second embodiment may be combined, or the configurations of the third embodiment and the fourth embodiment may be combined.

[0052] The above describes a configuration in which the first partial display area 111 and the second partial display area 112 are disposed at the same distance from the center point 11c of the display panel 11a, but this is merely an example for facilitating comparison and does not limit the present disclosure. When the positions of the display panel 11a and the projection optical system 20 are shifted in the first direction (±X direction) with respect to the incident diffraction layer 51b, or the emission directions in which the partial image lights ML1 and ML2 are emitted from the partial display areas 111 and 112 are tilted at tilt angles AT1 and AT2 according to the positions of the partial display areas 111 and 112 in the first direction (±X direction), respectively, if the two partial display areas 111 and 112 are at different positions in the first direction (±X direction), even if the first partial display area 111 and the second partial display area 112 have the same shape and area, the light flux widths W1 and W2 are different.

[0053] In a specific embodiment, a virtual image display device includes a display panel that emits image light, a projection optical system that collimates the image light from the display panel, a light guide plate that guides the image light, an incident diffraction optical system that causes the image light from the projection optical system to be incident on the light guide plate, and an exit diffraction optical system that emits the image light from the light guide plate, wherein the display panel includes a first partial display area and a second partial display area that is arranged in a first direction in which the wearer's eyes are aligned as viewed from the first partial display area and has the same area and shape as the first partial display area, wherein the image light emitted from the display panel includes a first partial image light emitted from the first partial display area and a second partial image light emitted from the second partial display area, and a first entrance area of ​​the entrance surface of the entrance diffraction optical system into which the first partial image light is incident is smaller than a second entrance area into which the second partial image light is incident.

[0054] In the above-mentioned virtual image display device, by providing a difference in the incident area when two partial image lights, which are respectively emitted from two different display areas included in the display panel, enter the light guide plate, it is possible to reduce brightness unevenness in the image light that exits the light guide plate and is observed by the eyes of the wearer, which occurs due to a difference in the reflection angle when the light is guided inside the light guide plate.

[0055] In a specific aspect of a virtual image display device, the optical axis center point where the central optical axis of the projection optical system intersects with the entrance surface of the entrance diffraction optical system is shifted from the center point of the display panel, and a second direction from the optical axis center point toward the center point includes a directional component parallel to the first direction, so that a first width in a virtual plane including the optical axis direction and first direction of a first partial image light guided inside the light guide plate is smaller than a second width in the virtual plane of a second partial image light guided inside the light guide plate.

[0056] In the above virtual image display device, a difference can be provided in the incidence area by shifting the center point of the display panel from the center point of the optical axis.

[0057] In a virtual image display device according to a specific aspect, the second direction includes a directional component of a third direction, which is a directional component parallel to the first direction, from the input diffractive optical system to the output diffractive optical system.

[0058] In a virtual image display device according to a specific embodiment, the second direction includes a directional component of a fourth direction that is opposite to the third direction.

[0059] In a specific embodiment, the virtual image display device further includes an emission direction changing optical system that changes the emission direction of light emitted from each of a plurality of pixels included in the display panel based on the position of each of the plurality of pixels on the display panel.

[0060] In the virtual image display device, the light emission direction is changed for each pixel, thereby making it possible to provide a difference in the incident area.

[0061] In a specific embodiment of a virtual image display device, a first angle of incidence at which a first partial image light from the emission direction changing optical system enters the projection optical system is smaller than a second angle of incidence at which a second partial image light from the emission direction changing optical system enters the projection optical system.

[0062] In a specific embodiment of the virtual image display device, a first angle of incidence at which a first partial image light from the emission direction changing optical system enters the projection optical system is greater than a second angle of incidence at which a second partial image light from the emission direction changing optical system enters the projection optical system.

[0063] In a specific embodiment of a virtual image display device, the emission direction changing optical system includes a microlens array in which a plurality of microlenses are arranged, each of which changes the radiation direction of light emitted from a plurality of pixels, and a predetermined distance is provided between the optical axis center point of each of the plurality of microlenses and the center point of each of the plurality of pixels, and the predetermined distance is determined based on the respective positions of the plurality of pixels on the display panel.

[0064] In the virtual image display device, a difference in the incident area can be provided by providing a different offset for each pixel between the center point of the pixel and the center point of the optical axis of the microlens.

[0065] In a specific embodiment of the virtual image display device, the display panel comprises a single-plate RGB panel having a plurality of sub-pixels that individually emit R (red), G (green) and B (blue) components of the image light for each of a plurality of pixels, and the emission direction changing optical system comprises a color filter array in which a plurality of color filters are arranged to provide color information to the light emitted from each of the plurality of sub-pixels, and a predetermined distance is provided between the center point of each of the plurality of color filters and the center point of each of the plurality of sub-pixels, and the predetermined distance is determined based on the positions of each of the plurality of sub-pixels on the display panel.

[0066] In the above virtual image display device, a difference in the incident area can be provided by providing a different offset between the center point of each subpixel and the center point of the color filter for each subpixel.

[0067] In a specific embodiment, the optical unit includes a display panel that emits image light, a projection optical system that collimates the image light from the display panel, a light guide plate that guides the image light, an incident diffraction optical system that causes the image light from the projection optical system to be incident on the light guide plate, and an exit diffraction optical system that emits the image light from the light guide plate, wherein the display panel includes a first partial display area and a second partial display area that is arranged in a first direction in which the wearer's eyes are aligned as viewed from the first partial display area and has the same area and shape as the first partial display area, wherein the image light emitted from the display panel includes a first partial image light emitted from the first partial display area and a second partial image light emitted from the second partial display area, and a first entrance area of ​​the entrance surface of the entrance diffraction optical system into which the first partial image light is incident is smaller than a second entrance area into which the second partial image light is incident. [Explanation of symbols]

[0068] 10...image light generating device, 11a...display panel, 11c...center point, 11d...display surface, 14a...light emitting element, 20...projection optical system, 21a, 21b...lens, 50...light guiding member, 51a...light guiding plate, 51b...entrance diffraction layer, 51c...exit diffraction layer, 51e...pupil enlargement grating layer, 71...holder, 88...driving circuit member, 90...user terminal, 100...optical unit, 100A, 100B...virtual image display device, 100C...support device, 102a, 102b...display driving unit , 103a, 103b... light guiding optical system, 110... partial display area (reference display area), 111, 112... partial display area, 200... HMD, 210, 211, 212... microlenses, 510... center point, AX1, AX2... optical axis, DE... pupil enlargement diffractive optical element, DI... input diffractive optical element, DO... output diffractive optical element, EY... eye, ML... image light, ML0, ML1, ML2... partial image light, OX... exit optical axis, PP... pupil position, US... wearer, W1, W2... light beam width

Claims

1. A display panel that emits image light; a projection optical system that collimates the image light from the display panel; a light guide plate that guides the image light; an incident diffraction optical system that causes the image light from the projection optical system to be incident on the light guide plate; an output diffraction optical system that outputs the image light from the light guide plate; Equipped with The display panel includes: A first partial display area; A second partial display area is disposed in a first direction in which both eyes of the wearer are aligned as viewed from the first partial display area, and has the same area and shape as the first partial display area; Including, The image light emitted from the display panel is a first partial image light emitted from the first partial display area; a second partial image light emitted from the second partial display area; and Including, A first incident area of ​​the incident surface of the incident diffractive optical system, on which the first partial image light is incident, is smaller than a second incident area on which the second partial image light is incident. Virtual image display device.

2. an optical axis center point where a central optical axis of the projection optical system intersects with an incident surface of the incident diffractive optical system is shifted from a center point where the central optical axis intersects with the display panel so that a first width in a virtual plane including an optical axis direction of the projection optical system and the first direction, of the first partial image light guided inside the light guide plate, is made smaller than a second width in the virtual plane of the second partial image light guided inside the light guide plate, A second direction from the optical axis center point toward the center point includes a direction component parallel to the first direction. The virtual image display device according to claim 1 .

3. The second direction includes a direction component of a third direction, which is a direction component parallel to the first direction, from the input diffraction optical system to the output diffraction optical system. The virtual image display device according to claim 2 .

4. The second direction includes a direction component of a fourth direction that is a direction opposite to a third direction that is a direction component parallel to the first direction from the input diffraction optical system to the output diffraction optical system. The virtual image display device according to claim 2 .

5. an emission direction changing optical system that changes an emission direction of light emitted from each of a plurality of pixels included in the display panel based on a position of each of the plurality of pixels on the display panel; Further equipped The virtual image display device according to claim 1 .

6. A first incident angle at which the first partial image light from the emission direction changing optical system is incident on the projection optical system is smaller than a second incident angle at which the second partial image light from the emission direction changing optical system is incident on the projection optical system. The virtual image display device according to claim 5 .

7. A first incident angle at which the first partial image light from the emission direction changing optical system is incident on the projection optical system is larger than a second incident angle at which the second partial image light from the emission direction changing optical system is incident on the projection optical system. The virtual image display device according to claim 5 .

8. The emission direction changing optical system includes: A microlens array in which a plurality of microlenses are arranged to change the radiation direction of the light emitted from the plurality of pixels Equipped with a predetermined distance is provided between the optical axis center point of each of the plurality of microlenses and the center point of each of the plurality of pixels; The predetermined distance is determined based on the positions of the pixels on the display panel.

8. The virtual image display device according to claim 5, 6 or 7.

9. The display panel includes: a single-plate RGB panel including a plurality of sub-pixels that individually emit light of an R (red) component, a G (green) component, and a B (blue) component of the image light for each of the plurality of pixels; Equipped with The emission direction changing optical system includes: a color filter array in which a plurality of color filters are arranged to give color information to the light emitted from each of the plurality of sub-pixels; Equipped with a predetermined distance is provided between a center point of each of the plurality of color filters and a center point of each of the plurality of sub-pixels; The predetermined distance is determined based on the positions of the sub-pixels on the display panel.

8. The virtual image display device according to claim 5, 6 or 7.

10. A display panel that emits image light; a projection optical system that collimates the image light from the display panel; a light guide plate that guides the image light; an incident diffraction optical system that causes the image light from the projection optical system to be incident on the light guide plate; an output diffraction optical system that outputs the image light from the light guide plate; Equipped with The display panel includes: A first partial display area; A second partial display area is disposed in a first direction in which both eyes of the wearer are aligned as viewed from the first partial display area, and has the same area and shape as the first partial display area; Including, The image light emitted from the display panel is a first partial image light emitted from the first partial display area; a second partial image light emitted from the second partial display area; and Including, A first incident area of ​​the incident surface of the incident diffractive optical system, on which the first partial image light is incident, is smaller than a second incident area on which the second partial image light is incident. Optical unit.

Images