Display device and display system

Abstract

To provide a small display device. [Solution] The display device has a light source 1, a display element 30 that modulates illumination light from the light source to generate image light, and an optical system 10 that directs the illumination light to the display element and emits the image light to the projection side. The optical system includes an optical function unit 20 that directs the illumination light to the display element side and the image light to the projection side. When the width of the effective modulation area in the display element in the first direction is W2 and the width of the optical function unit in the first direction is W1, 0

Description

[Technical Field]

[0001] The present invention relates to a display device including a head-mounted display (HMD) and smart glasses such as augmented reality (AR) glasses. [Background technology]

[0002] As a display device that guides illumination light from a light source to a display element and projects image light from the display element, Patent Document 1 discloses one that has an optical system using a polarizing beam splitter, and Patent Document 2 discloses one that has an optical system that forms a round-trip optical path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 8,300,159 [Patent Document 2] U.S. Patent No. 11,256,093 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for further miniaturization of such display devices. [Means for solving the problem]

[0005] A display device according to one aspect of the present invention includes a light source, a display element that generates image light by modulating illumination light from the light source, and an optical system that directs the illumination light to the display element and emits the image light to a projection side. The optical system includes an optical function unit that directs the illumination light to the display element side and the image light to the projection side. When the width of the effective modulation area of ​​the display element in a first direction is W2 and the width of the optical function unit in the first direction is W1, 0 <W1 / W2≦1.0 The present invention is characterized in that the following conditions are satisfied:

[0006] Another aspect of the present invention provides a display device that includes a light source, a display element that modulates illumination light from the light source to generate image light, and an optical system that directs the illumination light toward the display element and emits the image light. The optical system includes an optical function unit that directs the illumination light toward the display element and directs the image light toward the projection side, and an optical element with positive refractive power that is arranged closer to the display element than the optical function unit. The optical function unit is characterized in that the width of the optical function unit is smaller than the width of the optical element in a first direction parallel to the effective modulation area of ​​the display element. Note that another aspect of the present invention also provides a display system that allows an observer to view an image formed by image light from the display device. [Effects of the Invention]

[0007] According to the present invention, a small-sized display device can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the configuration of a display device according to a first embodiment. [Figure 2] FIG. 10 is a diagram showing the effect of the first embodiment. [Figure 3] FIG. 10 is a diagram showing the configuration of a display device according to a second embodiment. [Figure 4] FIG. 10 is a diagram showing the configuration of a display device according to a third embodiment. [Figure 5] FIG. 10 is a diagram showing the configuration of a display device according to a fourth embodiment. [Figure 6] FIG. 10 is a diagram showing the configuration of a display device that is a modified example of the fourth embodiment. [Figure 7] FIG. 10 is a diagram showing the configuration of a display device that is another modified example of the fourth embodiment. [Figure 8] FIG. 10 is a diagram showing the configuration of a display device according to a fifth embodiment. [Figure 9] FIG. 13 is a diagram showing the configuration of a display device that is a modified example of the fifth embodiment. [Figure 10] FIG. 10 is a diagram showing the configuration of a light source unit in the third embodiment. [Figure 11] FIG. 11 is a diagram showing the configuration of a polarization conversion element in the light source unit shown in FIG. [Figure 12] FIG. 10 is a diagram showing another configuration of the light source unit in the third embodiment. [Figure 13] FIG. 13 is a diagram showing the configuration of a display system according to a sixth embodiment. [Figure 14] FIG. 13 is a diagram showing the configuration of a display device in a display system according to a sixth embodiment. [Figure 15] FIG. 20 is a diagram showing another configuration of the display device in the display system of the sixth embodiment. [Figure 16] FIG. 10 is a diagram showing another configuration of the optical function unit. [Figure 17] FIG. 13 is a diagram showing the configuration of an in-vehicle display system according to a seventh embodiment. [Figure 18] FIG. 13 is a diagram showing the configuration of a projector according to an eighth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Example]

[0010] 1 shows the configuration (YZ cross section) of a display device 100a according to Example 1. As will be described later, the display device 100a is placed on the head (in front of the face) of a viewer as an HMD or smart glasses, or is used in an in-vehicle display system or a projector.

[0011] Illumination light emitted from the light source unit 1 of the display device 100a is guided to the display element 30 via an optical function unit 20 arranged in the projection optical system 10 and a positive lens 40a which is a part of the optical element of the projection optical system 10. In Fig. 1, the Z direction is the direction in which the optical axis of the projection optical system 10 extends, the direction perpendicular to the optical axis in a YZ cross section as a first cross section including the optical axis and a normal to the surface on which the optical function unit 20 is provided is the Y direction, and the direction perpendicular to the Z direction and the Y direction is the X direction.

[0012] The display element 30 is configured by a reflective liquid crystal element (LCOS: Liquid crystal on silicon). A reflective liquid crystal element is an element that modulates and reflects incident light according to the orientation direction of the liquid crystal.

[0013] The optical function unit 20 is composed of a polarization beam splitter (PBS) held between two prisms. The polarization beam splitter is an element that reflects or transmits incident light depending on the polarization state of the light. The two prisms and the polarization splitting surface disposed between them are sometimes collectively referred to as the polarization splitter, but the optical function unit 20 in this embodiment corresponds to the polarization splitting surface. In other words, the optical function unit is a part that actually has the function of reflecting and transmitting light, and does not include other parts.

[0014] Linearly polarized light (S-polarized light) as illumination light emitted from the light source unit 1 is reflected by the optical function unit 20 and deflected toward the display element 30, and passes through the positive lens 40a to enter the display element 30. The illumination light incident on the display element 30 is modulated according to the original image to be formed (displayed) on the modulation surface of the display element 30. This generates image light. At this time, the phase of the image light is also modulated by the liquid crystal and it leaves the display element 30 as P-polarized light.

[0015] Image light from the display element 30 is converged by passing through the positive lens 40a, passes through the optical function unit 20, and further passes through a lens group 40b made up of multiple lenses in the projection optical system 10 to reach a pupil (exit pupil) P on the projection side. In this way, the image light is projected onto the viewer's eye located at the position of the pupil P (hereinafter referred to as the pupil position) or onto a light guide element (described later). The positive lens 40a is located closest to the display element in the projection optical system 11, and has the largest outer diameter.

[0016] The function of the positive lens 40a disposed between the optical function unit 20 and the display element 30 will be described using Figures 2(a) and (b). Figures 2(a) and (b) show the first cross section (YZ cross section). The first cross section is also a cross section parallel to the first side of the effective modulation area of ​​the modulation surface (display surface) of the display element 30, which modulates light according to the original image. In the following description, the direction parallel to the first side (Y direction) will be referred to as the first direction. The effective modulation area of ​​the display element 30 has a rectangular shape with an aspect ratio of 16:9, 4:3, etc., and in this embodiment, the first side is the short side of the effective modulation area. However, the first side may also be the long side of the effective modulation area.

[0017] A divergent light beam (F-number light beam) within a certain angular range is emitted from the display element 30. When the optical function unit 20a and the display element 30 are disposed close to each other without the positive lens 40a as shown in FIG. 2(a), the width W1' of the optical function unit 20a in the first direction becomes larger than the width (length of the short side) W2 of the effective modulation area of ​​the display element 30 in the first direction (W1' > W2). In addition, the distance between the display element 30 and the lens group 40b, which is disposed closer to the pupil (projection side) than the optical function unit 20a, increases, so that both the overall length of the projection optical system and the outer diameter of the lens group disposed closest to the display element (optical function unit side) increase.

[0018] In contrast to this, by disposing a positive lens 40a between the optical function unit 20 and the display element 30 as shown in Fig. 2(b), the divergent light beam emitted from the display element 30 can be converged and made incident on the optical function unit 20. As a result, the width W1 in the first direction of the optical function unit 20 can be made smaller than W1' in the case of Fig. 2(a), and furthermore, can be made equal to or smaller than W2 (W1≦W2) as shown in Fig. 1. That is, the optical function unit 20 can be made smaller. Also, as shown in FIG. 1, the outer diameter of the lens group 40b arranged on the pupil side of the optical function unit 20 and the overall length of the projection optical system 10 can be reduced. Furthermore, by arranging the first cross section of the optical function unit 20 so that it is parallel to the short side, which serves as the first side, of the display element, the optical function unit 20 can be made even smaller. As a result, the entire display device can be made smaller. Moreover, the positive lens 40a allows the chief ray of the illumination light incident on various positions on the display element 30 to be incident on the display element 30 in an ideal direction, approximately perpendicular to the display element 30.

[0019] As described above, the optical function portion in this embodiment is a portion that actually has the functions of reflecting and transmitting light, and its width in the first direction is not the width in the first direction of the prism that holds the optical function portion. In other words, even if the prism is made larger than the optical function portion in the first direction or has a held portion that is held by the housing (lens barrel), and the width of the prism is greater than W1, the width in the first direction of the optical function portion is W1.

[0020] The optical element disposed between the optical function unit 20 and the display element 30 only needs to have the function of converging the light beam (deflecting the chief ray toward the optical axis), and may be a biconvex lens as shown in Fig. 2(b), a plano-convex lens, or a meniscus lens. Furthermore, a diffractive optical element, a meta-optical element, or a computer-generated hologram (CGH) element that controls the wavefront using a microstructure may be used, or a holographic optical element may be used.

[0021] In this embodiment and other embodiments described later, it is preferable that at least one of the conditions of the following expressions (1) to (9) be satisfied.

[0022] The width W1 of the optical function portion 20 in the first direction and the width W2 of the effective modulation area of ​​the display element 30 in the first direction are 0 <W1 / W2≦1.0 (1) It is preferable that the following condition be satisfied. By miniaturizing the optical function unit 20 so that this condition is satisfied, the projection optical system 10 and the display device can also be miniaturized. It is more preferable that the upper limit value of formula (1) be 0.9, 0.8, 0.7, 0.6, 0.5, or 0.4.

[0023] Furthermore, when the distance on the optical axis from the pupil position of the projection optical system 10 to the optical function unit 20 is L1, and the distance on the optical axis from the pupil position to (the modulation surface of) the display element 30 is L2, 0 <L1 / L2≦0.7 (2) It is preferable to satisfy the following condition. By satisfying this condition, the optical function unit 20 can be made even smaller. Note that, as in Examples 4 to 6 described below, when image light from the display element 30 reaches the pupil P after being reflected by the optical function unit 20 or other reflective surfaces, the "distance on the optical axis" corresponds to the distance along the central ray that is emitted from the center of the effective modulation area of ​​the display element, is reflected, and reaches the center of the pupil P. It is more preferable to set the upper limit value of formula (2) to 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1.

[0024] Furthermore, when the diagonal length of the effective modulation area of ​​the display element 30 is H, 1.0≦L2 / H≦4.0 (3) It is preferable to satisfy the following condition. By satisfying this condition, it is possible to further reduce the size of the projection optical system 10. It is more preferable to set the upper limit value of the formula (3) to 3.0 or 2.0.

[0025] Furthermore, when the focal length of the optical element having refractive power arranged closest to the display element in the projection optical system 10 is denoted by ff, and the focal length of the entire projection optical system 10 is denoted by f, then: ff / f≦2.5 (4) It is preferable to satisfy the following condition. By satisfying this condition, the projection optical system 10 can be made more compact. Note that if the value of ff / f is too small, it may become difficult to correct aberrations, so 0.3≦ff / f≦2.5 (4a) It is also preferable to set the upper limit of the formula (4) to 2.0, 1.5 or 1.0.

[0026] A flat element without refractive power, such as a cover glass, a wave plate, or a phase compensation plate, may be disposed between the display element 30 and the positive lens 40a. By having dust adhere to the cover glass rather than the modulation surface of the display element 30, it is possible to prevent a clear image of the dust from appearing at the pupil position. Furthermore, by disposing a wave plate or a phase compensation plate, it is possible to improve the contrast and quality of the image displayed by the image light.

[0027] 2(b), since most of the image light is incident obliquely on the optical function unit (polarization separation element) 20, it is desirable to use an element that has low dependency on the angle of incidence for the optical function unit 20. Specifically, it is desirable to use a wire grid polarizer or a dielectric or film having 100 or more layers stacked.

[0028] Furthermore, in order to change the polarization state of the linearly polarized light emitted from the projection optical system 10 to the pupil P, a polarizing element such as a half-wave plate may be disposed closer to the pupil than the optical function unit 20. In this case, the half-wave plate may be disposed by adhering it to a light-transmitting substrate (flat plate) that holds it, or may be joined by adhesive or the like to an optical element in the projection optical system. [Example]

[0029] 3 shows the configuration (YZ cross section) of a display device 100b of Example 2. The display device 100b of this example differs from Example 1 in the arrangement of the optical function unit 21 within the projection optical system 11. Specifically, a lens group 41b composed of a plurality of lenses is arranged between the display element 30 and the optical function unit 21. A positive lens 41a having the largest outer diameter within the projection optical system 11 is arranged closest to the display element of the lens group 41b. Furthermore, a lens group 41c composed of a plurality of lenses is arranged closer to the pupil than the optical function unit 21.

[0030] According to this configuration, the optical function unit 21 is disposed at a position where the image light converges to have a smaller beam diameter than in Example 1, so that the optical function unit 21 can be miniaturized so that the width W1 in the first direction is smaller. Also, the outer diameter of the lens group 40c and the overall length of the projection optical system 11 can be reduced. [Example]

[0031] FIG. 4 shows the configuration (YZ cross section) of a display device 100c of Example 3. The display device 100c of this example differs from Examples 1 and 2 in the arrangement of the optical function unit 22 within the projection optical system 12. Specifically, the optical function unit 22 is arranged closest to the pupil in the projection optical system 12. A lens group 42b composed of a plurality of lenses is arranged between the display element 30 and the optical function unit 22. A positive lens 42a having the largest outer diameter (width in the first direction) within the projection optical system 12 is arranged closest to the display element of the lens group 42b. Furthermore, a lens 42c having the smallest outer diameter (width in the first direction) within the projection optical system 12 is arranged closest to the pupil of the lens group 42b. The width W1 of the optical function unit 22 in the first direction is smaller than the width of the lens 42c.

[0032] According to this configuration, the optical function unit 22 is disposed at a position in the projection optical system 12 where the image light converges to have the smallest beam diameter, so that the optical function unit 22 can be made even smaller in size so that the width W1 in the first direction is smaller than in Examples 1 and 2. As a result, the overall length of the projection optical system 11 can be made even shorter. [Example]

[0033] 5 shows the configuration (YZ cross section) of a display device 100d of Example 4. The display device 100d of this example differs from Example 3 in the arrangement of the light source unit 1. In this example, components common to Example 3 are assigned the same reference numerals as in Example 3.

[0034] In this embodiment, illumination light (P polarized light) emitted from the light source unit 1 and incident on the projection optical system 12 passes through the optical function unit 22, passes through the lens group 42b, and is incident on the display element 30. On the other hand, image light (S polarized light) emitted from the display element 30 passes through the lens group 42b, is reflected and deflected by the optical function unit 22, and reaches the pupil P.

[0035] In this way, by changing the position of the light source unit 1 compared to Example 3, it is possible to change the direction in which the image light is emitted (the orientation of the pupil P). Furthermore, if the image light that reaches the pupil P is S-polarized, the configuration of Example 3 requires a half-wave plate on the pupil side of the optical function unit 22, but this example does not require a half-wave plate.

[0036] 6, a light deflection element 50 may be disposed in the optical path from the light source unit 1 to the optical function unit 22. The light deflection element 50 reflects (deflects) the illumination light emitted from the light source unit 1 twice and makes it incident on the optical function unit 22. With this configuration, the light source unit 1 and the optical function unit 22 can be arranged in parallel in the Y direction. The light deflection element 50 may be an integrated optical element having two reflective surfaces, or may be composed of only two reflective surfaces (mirrors).

[0037] 7, a region through which part of the illumination light can pass may be provided on each of the two reflecting surfaces of the optical deflector element 50, and light receivers 200a and 200b may be provided to receive the illumination light that has passed through the region. This makes it possible to measure the amount and color of the illumination light and control the light source unit 1 based on the measurement results, thereby adjusting the brightness and color of the displayed image. [Example]

[0038] 8 shows the configuration (YZ cross section) of a display device 100g of Example 5. In the display device 100g of this example, the configurations of the display element 31 and the optical function unit 23 are different from those of the display element 30 and the optical function unit 22 of Example 3. In this example, components common to Example 3 are denoted by the same reference numerals as in Example 3.

[0039] The display element 31 in this embodiment is composed of a mirror element (digital micromirror device: DMD) in which tiny movable mirrors are arranged two-dimensionally. The DMD generates image light by controlling the direction in which illumination light is reflected by switching the tilt (ON / OFF) of the movable mirrors that make up each pixel. In this case, the chief ray of the illumination light is incident from a direction tilted with respect to the normal to the modulation surface (the surface on which the movable mirrors are arranged) of the display element 31, and the chief ray of the image light is deflected in a direction parallel to the normal. When such a DMD is used, the illumination light may be unpolarized light.

[0040] The optical function unit 23 is configured as a TIR (Total Internal Reflection) prism, with two right-angle prisms (entrance prism 23a and exit prism 23b) having slopes that form an angle of more than 45° with respect to a plane perpendicular to the optical axis, facing each other with an air gap between them. Illumination light incident on the entrance prism 23a from the light source unit 1 is totally reflected at the interface between the slope and the air gap and deflected toward the display element. As described above, the slope of the entrance prism 23a forms an angle more acute than 45° with respect to a plane perpendicular to the optical axis. Therefore, the chief ray of the illumination light that enters the entrance prism 23a from a direction perpendicular to the optical axis and is totally reflected by the slope enters the display element (DMD) 31 via the lens group 42b from a direction tilted with respect to the normal to its modulation surface.

[0041] The chief ray of the image light reflected by the display element 31 is emitted in a direction parallel to the normal to the modulation surface and is incident on the entrance prism 23a via the lens group 42b. At this time, the chief ray of the image light is incident on the slope of the entrance prism 23a at an angle different from the angle at which total reflection occurs, and therefore passes through the slope without being totally reflected, and then passes through the exit prism 23b to reach the pupil P.

[0042] In this embodiment, the width of the optical function section 23 in the first direction is the width in the first direction of the inclined surface of the entrance prism 23a that totally reflects the illumination light and transmits the image light.

[0043] As shown in FIG. 9, a display device 100h as a modified example can have an optical function unit 24 tilted at a 45° angle by utilizing the angular dependency of a dielectric layer provided between two prisms as the optical function unit 24 tilted with respect to a plane perpendicular to the optical axis. Specifically, the chief ray of illumination light from the light source unit 1 is tilted from a plane perpendicular to the optical axis and incident on the dielectric layer tilted at a 45° angle with respect to the optical axis. As in FIG. 8, the dielectric layer reflects the illumination light toward the display element and transmits the image light. The width of the optical function unit 24 in the first direction is the width of the dielectric layer in the same direction.

[0044] According to this embodiment, even when a DMD is used as the display element, the optical function section 24 can be made compact, and the overall length of the projection optical system 12 can be reduced.

[0045] Numerical Examples 1 to 3 corresponding to Examples 1 to 3, respectively, are shown below. In each numerical example, the surface number i indicates the order of the surface when counted from the pupil side. The first surface is the pupil surface where the pupil P is located. r is the radius of curvature (mm) of the ith surface from the pupil side, d is the lens thickness or air gap (mm) on the optical axis between the ith and (i+1)th surfaces, and nd is the refractive index at the d-line of the optical material between the ith and (i+1)th surfaces. νd is the Abbe number based on the d-line of the optical material between the ith and (i+1)th surfaces.

[0046] The Abbe number νd, based on the d-line, is expressed as νd = (Nd-1) / (NF-NC), where Nd, NF, and NC are the refractive indices at the Fraunhofer d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm). The effective diameter is the radius (mm) of the area on the i-th lens surface through which light rays that contribute to image formation pass.

[0047] BF represents the back focus (mm). The back focus is the distance on the optical axis from the surface of the projection optical system closest to the display element (the final surface) to the modulation surface of the display element, expressed as an air-equivalent length. The total lens length is the distance on the optical axis from the pupil position of the projection optical system to the final surface plus the back focus.

[0048] An "*" next to a surface number indicates that the surface has an aspherical shape. The aspherical shape is expressed by the following formula, where x is the displacement from the vertex of the surface in the optical axis direction (Z direction), h is the height from the optical axis in a direction perpendicular to the optical axis, the direction of light travel is positive, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, and A8 are aspheric coefficients. The conic constant and aspheric coefficient "e±M" are multiplied by x 10 ±M means.

[0049] x=(h 2 / R) / [1+√{1-(1+k)(h / R) 2}] +A4×h 4 +A6×h 6 +A8×h 8 Moreover, values ​​corresponding to the above-mentioned conditional expressions (1) to (4) in Numerical Examples 1 to 3 are summarized in Table 1. [Numerical example 1] Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 (pupil) ∞ 0.50 1.30 2 4.216 1.26 2.05090 26.9 1.87 3 -5.704 0.50 1.80810 22.8 2.04 4 3.590 0.77 2.14 5* -5.646 1.22 1.85135 40.1 2.52 6 -1.863 0.50 1.72825 28.5 3.00 7 -25.475 1.77 3.79 8 ∞ 5.00 2.00100 29.1 5.84 9 ∞ 0.49 8.35 10 21.220 2.51 1.75500 52.3 9.50 11 -12.415 1.99 9.82 Modulation plane ∞ Aspheric data 5th page K = 8.99977e+00 A 4=-1.14776e-03 A 6=-2.79821e-04 Various data Zoom ratio 1.00 Focal length 10.44 F-number 8.00 Half angle of view (°) 24.44 Image height 4.74 Lens length 16.51 BF 1.99 d11 1.99 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 10.44 14.53 8.23 ​​-8.45 Single lens data Lens starting surface focal length 1 1 2.47 2 3 -2.66 3 5 2.84 4 6 -2.78 5 8 0.00 6 10 10.72 [Numerical example 2] Unit: mm Surface Data Surface number rd nd νd Effective diameter 1(pupil) ∞ 0.50 1.29 2 3.861 1.17 2.00100 29.1 1.88 3 -22.115 0.50 1.80810 22.8 2.04 4 2.813 0.77 2.15 5 ∞ 3.00 2.00100 29.1 2.88 6 ∞ 0.15 4.58 7* 6.667 1.33 1.88202 37.2 5.41 8* 70.551 1.40 5.43 9 -5.040 0.60 1.80810 22.8 5.53 10 17.945 0.94 6.64 11* 9.781 3.65 1.88202 37.2 9.15 12 -7.713 2.00 10.06 Modulation plane ∞ Aspheric data Side 7 K = 0.00000e+00 A 4=-7.33908e-03 A 6= 9.60556e-04 A 8=-2.39833e-05 Side 8 K = 0.00000e+00 A 4=-9.74705e-03 A 6= 8.90716e-04 Page 11 K = 0.00000e+00 A 4=-3.09581e-03 A 6= 1.17792e-04 A 8=-1.93166e-06 Various data Zoom ratio 1.00 Focal length 10.34 F-number 8.00 Half angle of view (°) 24.64 Image height 4.74 Lens total length 16.00 BF 2.00 d12 2.00 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 10.34 14.00 10.24 -8.35 Single lens data Lens starting surface focal length 1 1 3.36 2 3 -3.06 3 5 0.00 4 7 8.27 5 9 -4.81 6 11 5.42 [Numerical example 3] Unit: mm Surface Data Surface number rd nd νd Effective diameter 1(Pupil) ∞ 0.00 1.27 2 ∞ 2.50 2.00100 29.1 1.27 3 ∞ 0.30 2.36 4 3.688 1.15 2.00100 29.1 2.93 5 16.823 0.50 1.80810 22.8 2.89 6 2.636 0.79 2.86 7* 5.936 1.74 1.88202 37.2 4.11 8* -9.268 0.40 4.30 9 -5.256 0.60 1.80810 22.8 4.30 10 7.880 2.36 4.85 11* 20.227 3.23 1.88202 37.2 9.71 12* -9.467 2.43 10.02 Modulation plane ∞ Aspheric data Side 7 K = 0.00000e+00 A 4=-2.04769e-04 A 6= 4.14667e-04 A 8=-1.57795e-05 Side 8 K = 0.00000e+00 A 4= 2.95488e-04 A 6= 1.48283e-04 Page 11 K = 0.00000e+00 A 4=-4.90803e-04 A 6= 2.84211e-05 A 8=-1.75674e-07 Side 12 K = 0.00000e+00 A 4=-2.94312e-04 A 6=-3.05013e-06 A 8= 7.95497e-07 Various data Zoom ratio 1.00 Focal length 10.19 F-number 8.00 Half angle of view (°) 24.97 Image height 4.74 Lens total length 16.00 BF 2.43 d12 2.43 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 10.19 13.57 7.87 -7.76 Single lens data Lens starting surface focal length 1 1 0.00 2 4 4.52 3 5 -3.93 4 7 4.34 5 9 -3.82 6 11 7.70

[0050] [Table 1]

[0051] [Configuration of light source unit 1] The configuration of the light source unit 1 will be described with reference to Figures 10, 11, and 12. Figure 10 shows the configuration (YZ cross section) of the light source unit 1 in the display device of Example 3. The light beam emitted from the light-emitting unit 60 is split by the first fly-eye lens 70a, and each split light beam is condensed near the second fly-eye lens 70b to form a light source image.

[0052] When the light-emitting unit 60 emits unpolarized light such as from an LED, a polarization conversion element 71 is provided near the second fly-eye lens 70b. The polarization conversion element 71 is an element in which PBSs 71a and half-wave plates 71b are alternately arranged, and converts incident unpolarized light into linearly polarized light (S-polarized light) in a specific polarization direction. Specifically, as shown in FIG. 11 , the S-polarized light of the incident unpolarized light is reflected by the two PBSs 71a and emitted, and the P-polarized light that has passed through the PBSs 71a is converted into S-polarized light by the half-wave plate 71b and emitted. The S-polarized light as illumination light emitted from the polarization conversion element 71 enters the projection optical system 12, is reflected by the optical function unit 22, and is guided to the display element 30. When the light-emitting unit 60 emits linearly polarized light such as from a laser, the polarization conversion element 71 is not necessary. In this case, as shown in Figure 12, the light source unit 1 can be composed of a light-emitting unit 60, a mask 72 as a light-blocking member having an opening of a similar shape to the display element 30, and an illumination lens 73. The mask 72 and the display element 30 are optically conjugate. The illumination lens 73 and the projection optical system 22 are arranged in tandem, and the magnification is determined by the ratio of the focal length F1' of the illumination lens 73 to the focal length f2 of the projection optical system 12. Because laser light has high directivity, light with a narrow beam diameter (a low F-number) can be effectively used. This makes it possible to realize an extremely compact display device. [Example]

[0053] Fig. 16 shows the configuration of a display system (HMD or smart glasses) of Example 6 including the display devices of Examples 1 to 5. Fig. 14 and Fig. 15 show the configuration when the display device 100c of Example 3 is used in the display system of this example.

[0054] The frame 700 holds a display optical system 500 arranged in front of the right and left eyes of an observer 1000, and a display device according to any one of Examples 1 to 5 provided for the right and left eyes, respectively. The pupil of the projection optical system of the display device coincides with the entrance portion of the display optical system 500. Here, with reference to FIG. 14 , a case will be described in which the display device according to Example 3 provided for the right eye and the display optical system 500 guide image light to the observer's right eye. The display device and display optical system 500 provided for the left eye similarly guide image light to the left eye.

[0055] The display device for the right eye includes, in its projection optical system 12, a lens group 42b including a positive lens 42a, and an incident portion of a light guide element 500a that constitutes a display optical system 500. The incident portion of the light guide element 500a is provided with an optical function unit 25 that corresponds to the optical function unit 22 shown in Fig. 4. The light guide element 500a has a first surface and a second surface that face each other.

[0056] The optical function unit 25 transmits illumination light from the light source unit 1 toward the display element 30 and reflects image light incident from the display element 30 toward the first surface of the light-guiding element 500a. The image light incident on the first surface is totally reflected by the first surface and directed toward the second surface, and the image light totally reflected by the second surface is directed toward the first surface. In this way, the image light propagates within the light-guiding element 500a while being totally reflected by the first and second surfaces of the light-guiding element 500a, and is emitted toward the right eye from an exit portion (not shown) of the light-guiding element 500a located in front of the right eye. This directs the image light to the right eye, allowing the viewer to view an image formed by the image light through the right eye. By allowing the right and left eyes to view images with parallax relative to each other, a stereoscopic image can be observed.

[0057] 18, an optical function unit 26 may be provided on the first surface of the light-guiding element 500b. The optical function unit 26 can be configured by a diffractive optical element having a fine grating structure with a pitch equal to or less than the wavelength λ of the image light, as shown in FIGS. 16(a) to 16(d). The diffractive optical element has optical anisotropy according to the polarization state of the incident light. Specifically, it has the property of diffracting and polarizing S-polarized light and transmitting P-polarized light as is. Therefore, illumination light (P-polarized light) from the light source unit 1 passes through the optical function unit 26 toward the display element 30, and image light (S-polarized light) from the display element 30 is diffracted by the optical function unit 26 and deflected toward the second surface of the light-guiding element 500b. The image light incident on the second surface is totally reflected by the second surface toward the first surface, and the image light totally reflected by the first surface toward the second surface. In this way, the image light propagates through the light-guiding element 500b while being totally reflected by the second and first surfaces of the light-guiding element 500b, and is emitted toward the right eye from an emission portion (not shown) of the light-guiding element 500b provided in front of the right eye.

[0058] The optical function section 26 is not limited to a diffractive optical element, but may also be a holographic element having optical anisotropy according to the polarization state.

[0059] 13, a control unit 730 is connected to the frame 700 to control the driving of the display element 30 and the light intensity of the light source unit 1. The control unit 730 may be arranged outside the frame 700 as shown in the figure and connected to the display device via wire or wireless communication, or may be arranged inside the frame 700.

[0060] Furthermore, a first information acquisition unit 710 including a camera that acquires pupil information indicating the position and movement (point of view or line of sight) of the pupil of the eye of the observer 1000 is attached to the frame 700. A control unit 730 corrects the position of the display image 1100 (the position where the original image is formed on the display element) based on the pupil information. A second information acquisition unit 720 including a camera that acquires external world (surroundings) information is also attached to the frame 700. The control unit 730 adjusts the light amount of the light source unit 1 (i.e., the brightness of the display image 1100) according to the brightness of the external world obtained from the external world information. [Example]

[0061] FIG. 17 shows the configuration of a head-up display (HUD) 750 as an in-vehicle display system of Example 7 using the display device 100 of any one of Examples 1 to 5. The HUD 750 has a projection optical system 800 separate from the projection optical system in the display device 100, a first information acquisition unit 720a, a second information acquisition unit 710a, and a control unit 730a. The HUD 750 is mounted on an automobile 900 as a moving body, and projects an image (virtual image) 1100a for supporting a user (driver or passengers) of the automobile 900 onto the windshield as a projection surface via the projection optical system 800. Note that the moving body may be a train, a ship, an airplane, or the like, in addition to an automobile.

[0062] The first information acquisition unit 720a includes a camera that acquires pupil information indicating the position and movement (point of view or line of sight) of the user's pupil EP. The control unit 730a corrects the position of the display image 1100a (the position where the original image is formed on the display element) based on the pupil information. The second information acquisition unit 710a includes a camera that acquires external world information. The control unit 730a adjusts the brightness of the display image 1100a according to the brightness of the external world obtained from the external world information, and superimposes the display image 1100a on the external world image obtained from the external world information. The second information acquisition unit 710a may acquire external world information not only from the front, but also from behind, to the sides, etc.

[0063] The control unit 730a determines the possibility of collision of the automobile 900 with an obstacle (object) obtained from external world information, and if there is a possibility of collision, issues a warning or controls any of the drive units (engine, motor, etc.), brakes, and steering of the automobile 900. Warning methods include issuing a warning sound, displaying warning information on the display screen of the car navigation system, and generating vibrations in the seat belt or steering. [Example]

[0064] 18 shows the configuration of an image projection device (projector) as a display system using the display device 100 of any one of Examples 1 to 5. Image light emitted from the display device 100 is projected onto a projection surface 1100b such as a screen via a projection optical system 800a separate from the projection optical system within the display device 100. This makes it possible to display an enlarged image (real image) of the original image displayed on the display element 30 on the projection surface 1100b. The projection surface 1100b may be flat or curved.

[0065] The control unit 730b drives the display element 30 in response to an image signal input from the outside, adjusts the amount of light from the light source section 1, and adjusts the zoom and focus of the projection optical system 800a.

[0066] The above-described embodiment includes the following configurations.

[0067] (Configuration 1) A light source and a display element that modulates illumination light from the light source to generate image light; an optical system that guides the illumination light to the display element and emits the image light to a projection side, the optical system includes an optical function unit that directs the illumination light toward a display element side and directs the image light toward a projection side, When the width of the effective modulation area of ​​the display element in the first direction is W2 and the width of the optical function portion in the first direction is W1, 0 <W1 / W2≦1.0 A display device characterized by satisfying the following conditions. (Configuration 2) the effective modulation area is a rectangular area, 2. The display device according to configuration 1, wherein the first direction is a direction parallel to a short side of the rectangular shape. (Configuration 3) When the distance on the optical axis from the pupil position of the optical system to the optical function unit is L1 and the distance on the optical axis from the pupil position to the display element is L2, 0 <L1 / L2≦0.7 3. The display device according to configuration 1 or 2, which satisfies the following conditions: (Configuration 4) When the distance on the optical axis from the pupil position to the display element is L2 and the diagonal length of the effective modulation area of ​​the display element is H, 1.0≦L2 / H≦4.0 4. The display device according to any one of configurations 1 to 3, wherein the following conditions are satisfied: (Configuration 5) 5. The display device according to any one of configurations 1 to 4, wherein the optical system includes an optical element having a positive refractive power that is disposed closer to the display element than the optical function unit. (Configuration 6) 6. The display device according to any one of configurations 1 to 5, wherein the optical element has the largest width in the first direction among the optical systems. (Configuration 7) The focal length of the optical element is ff, When the focal length of the optical system is f, ff / f≦2.5 6. The display device according to configuration 5, wherein the following conditions are satisfied: (Configuration 8) 8. The display device according to any one of configurations 1 to 7, wherein the light source includes a light blocking member that has an opening having a similar shape to the display element and is optically conjugate with the display element. (Configuration 9) 9. The display device according to any one of configurations 1 to 8, wherein the display element is a reflective liquid crystal element. (Configuration 10) A light source and a display element that modulates illumination light from the light source to generate image light; an optical system that causes the illumination light to be incident on the display element and emits the image light, the optical system includes an optical function unit that directs the illumination light toward a display element side and directs the image light toward a projection side, and an optical element that has a positive refractive power and is disposed closer to the display element side than the optical function unit, 10. A display device, wherein the width of the optical function portion is smaller than the width of the optical element in a first direction parallel to an effective modulation area of ​​the display element. (Configuration 11) 9. The display device according to configuration 8, wherein the optical element is an optical element in the optical system that has the largest width in the first direction. (Configuration 12) 10. The display device according to configuration 8 or 9, wherein the optical element is an optical element in the optical system that has the smallest width in the first direction. (Configuration 13) 11. The display device according to configuration 10, wherein the optical function section is disposed on the most projection side of the optical system. (Configuration 14) A display device according to any one of configurations 1 to 13, A display system in which an observer is allowed to view an image formed by the image light emitted from the display device. (Configuration 15) 15. The display system according to configuration 13 or 14, further comprising a light guide element that guides the image light emitted from the display device to the viewer's eye.

[0068] The embodiments described above are merely representative examples, and various modifications and alterations are possible to each embodiment when implementing the present invention. [Explanation of symbols]

[0069] 1 Light source section 10~12 Projection optical system 20~26) Optical function section 30 Display element 40a, 41a, 42a positive lenses

Claims

1. A light source and a display element that modulates illumination light from the light source to generate image light; an optical system that guides the illumination light to the display element and emits the image light to a projection side, the optical system includes an optical function unit that directs the illumination light toward a display element side and directs the image light toward a projection side, When the width of the effective modulation area of ​​the display element in the first direction is W2 and the width of the optical function portion in the first direction is W1, 0<W1 / W2≦1.0 A display device characterized by satisfying the following conditions.

2. the effective modulation area is a rectangular area, The display device according to claim 1 , wherein the first direction is parallel to a short side of the rectangular shape.

3. When the distance on the optical axis from the pupil position of the optical system to the optical function unit is L1 and the distance on the optical axis from the pupil position to the display element is L2, 0<L1 / L2≦0.7 2. The display device according to claim 1, wherein the following conditions are satisfied:

4. When the distance on the optical axis from the pupil position to the display element is L2 and the diagonal length of the effective modulation area of ​​the display element is H, 1.0≦L2 / H≦4.0 2. The display device according to claim 1, wherein the following conditions are satisfied:

5. 2. The display device according to claim 1, wherein the optical system includes an optical element having a positive refractive power, which is disposed closer to the display element than the optical function unit.

6. The display device according to claim 1 , wherein the optical element has the largest width in the first direction among the optical systems.

7. The focal length of the optical element is ff, When the focal length of the optical system is f, ff / f≦2.5 6. The display device according to claim 5, wherein the following conditions are satisfied:

8. 2. The display device according to claim 1, wherein the light source includes a light blocking member that has an opening having a shape similar to that of the display element and is optically conjugate with the display element.

9. 2. The display device according to claim 1, wherein the display element is a reflective liquid crystal element.

10. A light source and a display element that modulates illumination light from the light source to generate image light; an optical system that causes the illumination light to be incident on the display element and emits the image light, the optical system includes an optical function unit that directs the illumination light toward a display element side and directs the image light toward a projection side, and an optical element that has a positive refractive power and is disposed closer to the display element side than the optical function unit, A display device, characterized in that the width of the optical function portion is smaller than the width of the optical element in a first direction parallel to an effective modulation area of ​​the display element.

11. The display device according to claim 8 , wherein the optical element is an optical element having the largest width in the first direction in the optical system.

12. The display device according to claim 8 , wherein the optical element is an optical element having the smallest width in the first direction in the optical system.

13. 11. The display device according to claim 10, wherein the optical function section is disposed on the most projection side of the optical system.

14. A display device according to any one of claims 1 to 13, A display system in which an observer is allowed to view an image formed by the image light emitted from the display device.

15. 14. The display system according to claim 13, further comprising a light guide element that guides the image light emitted from the display device to the viewer's eye.

Images