Eyepiece optical system and image display device having the same

Abstract

To provide an eyepiece optical system that prevents the occurrence of ghost and is advantageous in that it does not interfere with the nose of an observer.SOLUTION: An eyepiece optical system includes a phase plate, a lens, and a polarization separation element, and guides light from an image display element to an exit pupil. The eyepiece optical system has a diagonal display viewing angle of 60 degrees or more. The lens is a resin lens that is circular when seen from an optical axis direction. The outer diameter of the lens, the distance between the eyepiece optical system and the eyeballs of an observer, and the half value of the diagonal display viewing angle are appropriately set.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an eyepiece optical system and is suitable for an image display device such as a head-mounted display.

Background Art

[0002] In order to realize a thin and wide-angle image display device, an eyepiece optical system that folds an optical path using polarization has been proposed (see Patent Documents 1 and 2). ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​The diagonal field of view of the eyepiece optical system is 60 degrees or more, and the lens is a circular resin lens when viewed from the optical axis direction. The first polarizer and the first phase plate have a non-circular first shape, the second phase plate and the polarization separation element have a non-circular second shape different from the first shape, and the first and second shapes have a shape for determining the phase between the first and second shapes, and are closest to the observer. When the outer diameter of the lens is Φ, the distance between the eyepiece optical system and the observer's eyeball is E, and the half-value of the diagonal display angle is θ, 1.5 ≤ Φ / (E·tanθ) ≤ 3.0 It is characterized by satisfying the following conditional expression. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an eyepiece optical system that is advantageous in that it suppresses the generation of ghosting and does not interfere with the observer's nose. [Brief explanation of the drawing]

[0008] [Figure 1] This is a configuration diagram of a head-mounted display, which is an example of an image display device having an eyepiece optical system according to the first embodiment. [Figure 2] This is an explanatory diagram of the eyepiece optical system for the right eye of the first embodiment. [Figure 3] This is an external view of the head-mounted display according to the first embodiment. [Figure 4] This is an explanatory diagram of the eyepiece optical system for the right eye of the first embodiment. [Figure 5] This is an explanatory diagram for adjusting the interpupillary distance of the head-mounted display according to the first embodiment. [Figure 6] This is an explanatory diagram illustrating the shape of elements other than the lens in the first embodiment. [Figure 7] This is a configuration diagram of a head-mounted display, which is an example of an image display device having an eyepiece optical system according to a second embodiment. [Figure 8] This is an explanatory diagram of the right eyepiece optical system of the second embodiment. [Figure 9] This is an explanatory diagram of the right eyepiece optical system of the second embodiment. [Figure 10] This is a configuration diagram of a head-mounted display, which is an example of an image display device having an eyepiece optical system according to a third embodiment. [Figure 11] This is an explanatory diagram of the right eyepiece optical system of the third embodiment. [Modes for carrying out the invention]

[0009] The embodiments of the present invention will be described in detail below with reference to the drawings. In each figure, the same reference numeral is used for identical components, and redundant explanations are omitted.

[0010] In each embodiment, the eyepiece optical system for the right eye will be described primarily, but the same applies to the eyepiece optical system for the left eye. [First Embodiment] Figure 1 is a diagram showing the configuration of a head-mounted display (HMD) 101, which is an example of an image display device having an eyepiece optical system according to this embodiment. The HMD 101 has lenses 104, 105, 106, 107, a right-eye image display element 108, and a left-eye image display element 109. The right-eye eyepiece optical system is formed by the lens (first lens) 104 and the lens (second lens) 105, and the left-eye eyepiece optical system is formed by the lens (first lens) 106 and the lens (second lens) 107. The right-eye image display element 108 and the left-eye image display element 109 are organic EL displays.

[0011] The right-eye eyepiece optical system projects the original image displayed on the right-eye image display element 108 as a magnified virtual image and guides it to the observer's right eye 102. The left-eye eyepiece optical system projects the original image displayed on the left-eye image display element 109 as a magnified virtual image and guides it to the observer's left eye 103. The focal length F1 of the right-eye and left-eye eyepiece optical systems is 12 mm, the horizontal display field of view is 55°, the vertical display field of view is 40°, and the diagonal display field of view is 65°. The distance between the HMD 101 and the observer's eyeball (eye relief) is 25 mm. For the observer to feel a sense of presence, a diagonal display field of view of 60 degrees or more is sufficient, but 75 degrees or more is desirable, and 80 degrees or more is even more desirable. Also, because the image display device would become larger, it is desirable that the diagonal display field of view be 100 degrees or less.

[0012] The eyepiece optical system of this embodiment has a configuration that folds the optical path using polarization. The optical path of the eyepiece optical system will be described for the right-eye eyepiece optical system. FIG. 2 is an explanatory diagram of the right-eye eyepiece optical system of this embodiment. The right-eye eyepiece optical system includes a polarizing plate (first polarizing plate) 110, a phase plate (first phase plate) 111, lenses 105 and 104, a phase plate (second phase plate) 113, and a polarization beam splitter (hereinafter referred to as PBS) 114, which are arranged in order from the side of the right-eye image display element 108. A half mirror 112 is deposited on the surface of lens 104 on the side of lens 105. The surface on which the half mirror 112 is deposited acts as a semi-transmissive reflective surface. That is, lens 104 is a semi-transmissive reflective element. The phase plates 113 and PBS 114 have a planar shape. The phase plates 111 and 113 are wavelength plates with a retardation of λ / 4.

[0013] In this embodiment, the polarization direction transmitted by the polarizing plate 110 and the slow axis of the phase plate 111 are inclined at 45°, the polarization direction transmitted by the polarizing plate 110 and the slow axis of the phase plate 113 are inclined at -45°, and the polarization direction transmitted by the polarizing plate 110 and the polarization direction transmitted by the PBS 114 are orthogonal. In such a configuration, the light emitted from the right-eye image display element 108 passes through the polarizing plate 110 and becomes linearly polarized light, and passes through the phase plate 111 and becomes circularly polarized light. Then, after passing through the half mirror 112, it passes through the phase plate 113 and becomes linearly polarized light. Since the polarization direction of this linearly polarized light is orthogonal to the polarization direction transmitted by the PBS 114, it is reflected by the PBS 114 and passes through the phase plate 113 and becomes circularly polarized light. Then, after being reflected by the half mirror 112, it passes through the phase plate 113 and becomes linearly polarized light. Since the polarization direction of this linearly polarized light coincides with the polarization direction transmitted by the PBS 114, it passes through the PBS 114 and is guided to the right eye 102 of the observer. The optical path of the left-eye eyepiece optical system is the same.

[0014] Since the eyepiece optical system of this embodiment has a configuration that folds the optical path using polarization, the HMD 101 can be made thinner, and the focal length of the eyepiece optical system can be shortened, so that a wide-angle image observation can be realized.

[0015] FIG. 3 is an external view of the HMD 101. Since the HMD 101 is a head-mounted image display device, it is desirable that it be lightweight. Therefore, it is desirable that the plurality of lenses constituting the ocular optical system be made of a resin having a specific gravity smaller than that of glass. In the present embodiment, the lenses 104 and 106 are resin plano-convex aspherical lenses to enhance the aberration correction effect. Also, the lenses 105 and 107 are resin double-sided aspherical lenses.

[0016] FIG. 4 is an explanatory view of the right-eye ocular optical system of the present embodiment. In the right-eye ocular optical system of the present embodiment, the position of the exit pupil is set to a position of 35 mm obtained by adding the eye relief (= 25 mm) to the radius of rotation of the eyeball (= 10 mm), and the exit pupil diameter is set to 6 mm. Thereby, even when the eyeball rotates to observe an image in the up, down, left, or right direction, the light in that direction enters the eyeball. In order for an observer wearing glasses to be able to wear the HMD 101, it is desirable that the eye relief be 15 mm or more. Also, when the eye relief becomes long, the outer diameter of the lens increases and the HMD 101 becomes larger, so it is desirable that the eye relief be 25 mm or less. That is, it is desirable that the eye relief be 15 mm or more and 25 mm or less.

[0017] The HMD 101 may have an interpupillary distance adjustment mechanism as shown in FIG. 5 so that observers with different interpupillary distances can comfortably observe. The interpupillary distance adjustment mechanism can move the ocular optical system and the image display element in the left-right direction (horizontal direction). Since the adjustment range of the interpupillary distance by the interpupillary distance adjustment mechanism is from 57 mm to 79 mm with respect to the average interpupillary distance of 63 mm, the HMD 101 can cover the interpupillary distances of many observers.

[0018] In this embodiment, molded resin lenses are used because they allow for low-cost mass production while achieving an aspherical shape advantageous for aberration correction. However, molded resin lenses tend to retain birefringence characteristics due to residual stress during molding. When a birefringent lens is used as the lens in this embodiment, a phase difference is introduced when light passes through, preventing the maintenance of the intended polarization state, and resulting in direct ghost light that is guided to the observer's eye without being reflected by PBS114. Furthermore, an unwanted phase difference is introduced to the light in the normal optical path after reflection by PBS114, causing some of the light transmitted by PBS114 to be reflected, reducing the amount of light observed.

[0019] Therefore, in this embodiment, the lens is a resin lens whose outer shape is circular when viewed from the optical axis direction. By making the lens shape circular, the lens can shrink isotropically during molding, thereby reducing the birefringence within the lens. However, when the lens shape is circular, the outer diameter of the lens increases in accordance with the widening of the field of view of the eyepiece optical system, causing the HMD101 to interfere with the observer's nose.

[0020] Therefore, in this embodiment, in order to reduce birefringence within the lens, the lens is made of circular resin, and the outer diameter of the lens is determined using the eye relief and diagonal display angle so that the HMD101 does not interfere with the observer's nose. Specifically, the outer diameter of the lens is determined so as to satisfy the following condition (1).

[0021] 1.5 ≤ Φ / (E·tanθ) ≤ 3.0 (1) Here, Φ is the outer diameter of the lens. E is the eye relief, which is the distance between the eyepiece optical system and the observer's eyeball. θ is the half-value of the diagonal viewing angle.

[0022] By satisfying condition (1), image observation can be performed without the eyepiece optics or HMD101 interfering with the observer's nose, even when HMD101 is adjusted to the smallest interpupillary distance. If the condition is not met, the outer diameter of the lens is too small relative to the eye relief and diagonal display field of view, and peripheral display images will not enter the lens, causing the peripheral parts of the observed image to become dark or invisible. If the condition is not met, the outer diameter of the lens is too large relative to the eye relief and diagonal display field of view, and HMD101 will interfere with the observer's nose. In this embodiment, the outer diameter Φ1 of lenses 104 and 106 is 42 mm, and the outer diameter Φ2 of lenses 105 and 107 is 43 mm.

[0023] Furthermore, it is preferable that the numerical range of conditional expression (1) be the numerical range of conditional expression (1a) below.

[0024] 2.0≦Φ / (E·tanθ)≦2.8 (1a) Furthermore, it is even more preferable to set the numerical range of condition (1) to the numerical range of condition (1b) below.

[0025] 2.3 ≤ Φ / (Etanθ) ≤ 2.7 (1b) When an observer wears the HMD101 in the usual manner and rotates their eyeball to observe the periphery (edge) of the eyepiece optical system, it is desirable that 30% or more of the light beam from the eyepiece optical system (light beam at the maximum horizontal or maximum vertical field of view) enters the exit pupil. As a result, the observer does not perceive a decrease in brightness. In the eyepiece optical system of this embodiment, as shown in Figure 4, when an observer observes the periphery of the eyepiece optical system, half of the light beam at the maximum horizontal field of view is guided to the exit pupil.

[0026] In this embodiment, since the lens is circular, it is desirable to hold it within the lens barrel. In that case, it is desirable that the lens barrel be configured to have a configuration that abuts the lens against the observer and a configuration that holds the lens on the side of the image display element in order to ensure eye relief. Also, in order to hold lens 104 in the lens barrel before lens 105, it is desirable that the outer diameter of lens 104 be smaller than the outer diameter of lens 105. The same applies to lenses 106 and 107.

[0027] In this embodiment, the surface on which the half-mirror 112 is deposited is a convex surface that is convex toward the right-eye image display element 108. By depositing the half-mirror 112 on the convex surface, it is possible to achieve a wider field of view while making the eyepiece optical system thinner. Furthermore, by making the convex surface on which the half-mirror 112 is deposited an aspherical shape, the aberration correction effect can be enhanced.

[0028] In this embodiment, a polarizing plate (second polarizing plate) may be placed between the PBS114 and the observer's eyeball to reduce ghosting from ambient light and enhance the contrast of the observed image.

[0029] In this embodiment, in order to achieve both a longer eye relief and a thinner eyepiece optical system, the observer-facing surface of the lens 104, on which the phase plate 113 and PBS 114 are formed, is flat. If the observer-facing surface is concave, the lens 104 becomes thicker to ensure eye relief at the periphery. Conversely, if the observer-facing surface is convex, the lens 104 becomes thicker to ensure the thickness of the lens edge. Therefore, in this embodiment, the lens 104 is a plano-convex lens.

[0030] In this embodiment, the phase plates 111 and 113 are waveplates with a phase difference of λ / 4, but the phase difference may be shifted from λ / 4 to cancel out birefringence in the lenses 104 and 105. In this case, it is desirable that the sum of the phase differences between lens 104 and phase plate 113 be between 3λ / 20 and 7λ / 20. It is also desirable that the sum of the phase differences between lens 105 and phase plate 111 be between 3λ / 20 and 7λ / 20. If it falls outside the above range, the intensity of ghost light increases, making it impossible to achieve natural observation.

[0031] In this embodiment, the right-eye image display element 108 emits unpolarized light as an organic EL, but it may also emit linearly polarized light as a liquid crystal display. In this case, the polarizing plate 110 becomes unnecessary, allowing for a thinner HMD 101 and a reduction in the number of components.

[0032] In this embodiment, the eyepiece optical system uses a PBS114 that switches between transmission and reflection based on the direction of linear polarization. However, a polarization separation element that switches between transmission and reflection based on the direction of circular polarization may also be used. In this case, the phase plate 113 becomes unnecessary, allowing for a thinner HMD101 and a reduction in the number of components.

[0033] In this embodiment, since the lens is circular, the polarizer 110, phase plates 111, 113, and PBS 114 are also circular. In order to align the phases of the polarizer 110 and phase plate 111 with the phase plates 113 and PBS 114, or to align the phases of the lens 104 with the phase plates 113 and PBS 114, it is desirable that at least one of the above elements has a shape for determining the phase. Specifically, the polarizer 110 and phase plate 111 may have the tab shape shown in Figure 6(a), and the phase plates 113 and PBS 114 may have the notches shown in Figure 6(b). [Second Embodiment] Figure 7 is a configuration diagram of a head-mounted display (HMD) 201, which is an example of an image display device having an eyepiece optical system according to this embodiment. The HMD 201 has lenses 204, 205, 206, 207, a right-eye image display element 208, and a left-eye image display element 209. The right-eye eyepiece optical system is formed by lens (first lens) 204 and lens (second lens) 205, and the left-eye eyepiece optical system is formed by lens (first lens) 206 and lens (second lens) 207. Lenses 204, 205 and lenses 206, 207 are cemented lenses, which can be easily held. The right-eye image display element 208 and the left-eye image display element 209 are organic EL displays.

[0034] The right-eye eyepiece optical system projects the original image displayed on the right-eye image display element 208 as a magnified virtual image and guides it to the observer's right eye 202. The left-eye eyepiece optical system projects the original image displayed on the left-eye image display element 209 as a magnified virtual image and guides it to the observer's left eye 203. The focal length of the right-eye and left-eye eyepiece optical systems is 13 mm, the horizontal display field of view is 60°, the vertical display field of view is 60°, and the diagonal display field of view is 78°. The distance between the HMD 201 and the observer's eyeball (eye relief) is 20 mm. For the observer to feel a sense of presence, a diagonal display field of view of 60 degrees or more is sufficient, but 75 degrees or more is desirable, and 80 degrees or more is even more desirable. Also, because the image display device would become larger, it is desirable that the diagonal display field of view be 100 degrees or less.

[0035] The eyepiece optical system of this embodiment has a configuration that folds the optical path using polarization. The optical path of the eyepiece optical system will be explained using the right eyepiece optical system. Figure 8 is an explanatory diagram of the right eyepiece optical system of this embodiment. The right eyepiece optical system includes a polarizer 210, a phase plate 211, lenses 205, 204, a phase plate 213, a polarization separation element (hereinafter referred to as PBS) 214, and a polarizer 215, arranged in order from the side of the right eye image display element 208. The polarizers 210, 215 and the phase plates 211, 213 are the first polarizer, second polarizer, first phase plate, and second phase plate, respectively. A half mirror 212 is deposited on the surface of lens 204 on the side of lens 205. The surface on which the half mirror 212 is deposited acts as a semi-transmissive reflective surface. That is, lens 204 is a semi-transmissive reflective element. The phase plates 213, PBS 214, and polarizer 215 are planar in shape. The phase plates 211 and 213 are waveplates with a phase difference of λ / 4.

[0036] In this embodiment, the polarization direction transmitted by the polarizer 210 and the slow axis of the phase plate 211 are tilted at 45°, the polarization direction transmitted by the polarizer 210 and the slow axis of the phase plate 213 are tilted at -45°, and the polarization direction transmitted by the polarizer 210 and the polarization direction transmitted by the PBS 214 are orthogonal. Also, the polarization direction transmitted by the PBS 214 and the polarization direction transmitted by the polarizer 215 are the same. In this configuration, light emitted from the right eye image display element 208 passes through the polarizer 210 to become linearly polarized, passes through the phase plate 211 to become circularly polarized. After that, it passes through the half mirror 212 and then through the phase plate 213 to become linearly polarized. Since the polarization direction of this linearly polarized light is orthogonal to the polarization direction transmitted by the PBS 214, it is reflected by the PBS 214 and passes through the phase plate 113 to become circularly polarized. After that, it is reflected by the half mirror 212 and then passes through the phase plate 213 to become linearly polarized. The linearly polarized light, whose polarization direction coincides with the polarization direction transmitted through PBS214, passes through PBS214 and the polarizer 215 and is guided to the observer's right eye 202. The same optical path is used for the left eyepiece optical system.

[0037] In this embodiment, a polarizing plate 215 is placed between the PBS 214 and the observer's right eye 202 to reduce ghosting from ambient light and enhance the contrast of the observed image.

[0038] As in this embodiment, by providing an eyepiece optical system that folds the optical path using polarization, the HMD201 can be made thinner, and the focal length of the eyepiece optical system can be shortened, thereby enabling wide-angle image observation.

[0039] Since the HMD201 is a head-mounted image display device, it is desirable that it be lightweight. Therefore, it is desirable that the multiple lenses constituting the eyepiece optical system be made of resin, which has a lower specific gravity than glass. In this embodiment, the aberration correction effect is enhanced by making lenses 204, 205, 206, and 207 as aspherical lenses made of resin.

[0040] In the eyepiece optical system of this embodiment, the exit pupil is positioned at 28 mm, which is the sum of the eye relief (=18 mm) and the radius of rotation of the eyeball (=10 mm), and the exit pupil diameter is 6 mm. This ensures that even when the eyeball rotates to observe images in all directions (up, down, left, or right), light from that direction enters the eyeball. It is desirable that the eye relief be 15 mm or more so that observers wearing glasses can also wear the HMD201. Furthermore, since a longer eye relief increases the outer diameter of the lens and makes the HMD201 larger, it is desirable that the eye relief be 25 mm or less. In other words, it is desirable that the eye relief be between 15 mm and 25 mm.

[0041] The HMD201 may have an interpupillary distance adjustment mechanism for moving the eyepiece optical system and image display element in the left-right direction (horizontal direction) to allow observation by observers with different interpupillary distances to observe comfortably.

[0042] In this embodiment, to minimize birefringence within the lens, a circular resin lens is used, while the outer diameter of the lens is determined using the eye relief and diagonal viewing angle to prevent the HMD201 from interfering with the observer's nose. Specifically, the outer diameter of the lens is determined to satisfy the aforementioned condition (1). In this embodiment, the outer diameter Φ3 of lenses 204 and 206 is 40.5 mm, and the outer diameter Φ4 of lenses 205 and 207 is 39 mm.

[0043] When an observer wears the HMD201 in the usual manner and rotates their eyeball to observe the periphery (edge) of the eyepiece optical system, it is desirable that 30% or more of the light beam from the eyepiece optical system (light beam at the maximum horizontal or maximum vertical field of view) enters the exit pupil. As a result, the observer does not perceive a decrease in brightness. In the eyepiece optical system of this embodiment, as shown in Figure 9, when an observer observes the periphery of the eyepiece optical system, 45% or more of the light beam at the maximum horizontal and maximum vertical field of view is guided to the exit pupil.

[0044] In this embodiment, since the lens is circular, it is desirable to hold it within the lens barrel. In that case, it is desirable that the lens barrel be configured to abut the lens against the observer and to hold the lens against the image display element in order to ensure eye relief. Also, since lenses 204 and 205 are joined together, it is desirable that the outer diameter of lens 204 be larger than the outer diameter of lens 205. The same applies to lenses 206 and 207.

[0045] In this embodiment, the surface on which the half-mirror 212 is deposited is a convex surface that is convex toward the right-eye image display element 108. By depositing the half-mirror 212 on a convex surface, it is possible to achieve a wider field of view while making the eyepiece optical system thinner. Furthermore, by making the convex surface on which the half-mirror 212 is deposited an aspherical shape, the aberration correction effect can be enhanced. Note that since lenses 204 and 205 are cemented lenses, the half-mirror 212 may also be deposited on the observer-side surface of lens 205. Even in that case, the surface on which the half-mirror 212 is deposited is a convex surface that is convex toward the right-eye image display element 208.

[0046] In this embodiment, in order to achieve both a longer eye relief and a thinner eyepiece optical system, the observer-side surface of the lens 204 on which the phase plate 213 and PBS 214 are formed is flat. Therefore, in this embodiment, the lens 204 is a plano-convex lens.

[0047] In this embodiment, the phase plates 211 and 213 are waveplates with a phase difference of λ / 4, but the phase difference may be shifted from λ / 4 to cancel out birefringence in the lenses 204 and 205. In this case, it is desirable that the sum of the phase differences between lens 204 and phase plate 213 be between 3λ / 20 and 7λ / 20. It is also desirable that the sum of the phase differences between lens 205 and phase plate 211 be between 3λ / 20 and 7λ / 20. If the values ​​fall outside this range, the intensity of ghost light increases, making it impossible to achieve natural observation. [Third Embodiment] Figure 10 is a configuration diagram of a head-mounted display (hereinafter referred to as HMD) 301, which is an example of an image display device having an eyepiece optical system according to this embodiment. The HMD 301 has lenses 304, 305, 306, 307, a right-eye image display element 308, and a left-eye image display element 309. The right-eye eyepiece optical system is formed by lens (first lens) 304 and lens (second lens) 305, and the left-eye eyepiece optical system is formed by lens (first lens) 306 and lens (second lens) 307. Lenses 304, 305 and lenses 306, 307 are cemented lenses, which can be easily held. The right-eye image display element 308 and the left-eye image display element 309 are organic EL displays.

[0048] The right-eye eyepiece optical system projects the original image displayed on the right-eye image display element 308 as a magnified virtual image and guides it to the observer's right eye 302. The left-eye eyepiece optical system projects the original image displayed on the left-eye image display element 309 as a magnified virtual image and guides it to the observer's left eye 303. The focal length of the right-eye and left-eye eyepiece optical systems is 14 mm, the horizontal display field of view is 80°, the vertical display field of view is 80°, and the diagonal display field of view is 100°. The distance between the HMD 301 and the observer's eyeball (eye relief) is 15 mm. For the observer to feel a sense of presence, a diagonal display field of view of 60 degrees or more is sufficient, but 75 degrees or more is desirable, and 80 degrees or more is even more desirable. Also, because the image display device would become larger, it is desirable that the diagonal display field of view be 100 degrees or less.

[0049] The eyepiece optical system of this embodiment includes a configuration that folds the optical path using polarization. The optical path of the eyepiece optical system is the same as that of the first or second embodiment, so a description is omitted.

[0050] As in this embodiment, by having an eyepiece optical system that folds the optical path using polarization, the HMD301 can be made thinner, and the focal length of the eyepiece optical system can be shortened, thereby enabling wide-angle image observation.

[0051] Since the HMD301 is a head-mounted image display device, it is desirable that it be lightweight. Therefore, it is desirable that the multiple lenses constituting the eyepiece optical system be made of resin, which has a lower specific gravity than glass. In this embodiment, the aberration correction effect is enhanced by making lenses 304, 305, 306, and 307 aspherical lenses made of resin.

[0052] In the eyepiece optical system of this embodiment, the exit pupil is positioned at 25 mm, which is the sum of the eye relief (=15 mm) and the radius of rotation of the eyeball (=10 mm), and the exit pupil diameter is 6 mm. This ensures that even when the eyeball rotates to observe images in all directions (up, down, left, or right), light from that direction enters the eyeball. It is desirable that the eye relief be 15 mm or more so that observers wearing glasses can also wear the HMD301. Furthermore, since a longer eye relief increases the outer diameter of the lens and makes the HMD301 larger, it is desirable that the eye relief be 25 mm or less. In other words, it is desirable that the eye relief be between 15 mm and 25 mm.

[0053] The HMD301 may have an interpupillary distance adjustment mechanism for moving the eyepiece optical system and image display element in the left-right direction (horizontal direction) to allow observers with different interpupillary distances to observe comfortably.

[0054] In this embodiment, to minimize birefringence within the lens, a circular resin lens is used, and the outer diameter of the lens is determined using the eye relief and diagonal viewing angle to prevent the HMD301 from interfering with the observer's nose. Specifically, the outer diameter of the lens is determined to satisfy the aforementioned condition (1). In this embodiment, the outer diameter Φ5 of lenses 304 and 306 is 39 mm, and the outer diameter Φ6 of lenses 305 and 307 is 37 mm.

[0055] When an observer wears the HMD301 in the usual manner and rotates their eyeball to observe the periphery (edge) of the eyepiece optical system, it is desirable that 30% or more of the light beam from the eyepiece optical system (light beam at the maximum horizontal or maximum vertical field of view) enters the exit pupil. As a result, the observer does not perceive a decrease in brightness. In the eyepiece optical system of this embodiment, as shown in Figure 11, when an observer observes the periphery of the eyepiece optical system, 35% or more of the light beam at the maximum horizontal and maximum vertical field of view is guided to the exit pupil.

[0056] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its gist. [Explanation of symbols]

[0057] 104, 105, 106, 107 lenses 204, 205, 206, 207 lenses 304, 305, 306, 307 lenses 108,208,308 Right eye image display element (image display element) 109,209,309 Left eye image display element (image display element) 111,113,211,213 Phase plate 114,214 Polarization Separators

Claims

1. An eyepiece optical system comprising a phase plate, a lens, and a polarization separation element, which guides light from an image display element to the exit pupil, The image display element has, in order from the side, a first polarizing plate, a first phase plate, the lens, a second phase plate, and the polarization separation element, The diagonal display field of view of the aforementioned eyepiece optical system is 60 degrees or more. The aforementioned lens is a resin lens that is circular when viewed from the direction of the optical axis. The first polarizer and the first phase plate have a non-circular first shape, and the second phase plate and the polarization separation element have a non-circular second shape different from the first shape. The first shape and the second shape have shapes for determining the phase between the first shape and the second shape, When the outer diameter of the lens closest to the observer is Φ, the distance between the eyepiece optical system and the observer's eyeball is E, and half of the diagonal display angle is θ, 1.5≦Φ / (E・tanθ)≦3.0 An eyepiece optical system characterized by satisfying the following conditional equation.

2. The eyepiece optical system according to claim 1, characterized in that the diagonal display angle of view is 75 degrees or more.

3. 2.0≦Φ / (E・tanθ)≦2.8 The eyepiece optical system according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

4. 2.3≦Φ / (E・tanθ)≦2.7 An eyepiece optical system according to any one of claims 1 to 3, characterized in that it satisfies the following conditional expression.

5. 15 mm ≤ E ≤ 25 mm An eyepiece optical system according to any one of claims 1 to 4, characterized in that it satisfies the following conditional expression.

6. The eyepiece optical system according to any one of claims 1 to 5, characterized in that when the observer observes the end of the eyepiece optical system, 30% or more of the light beam from the eyepiece optical system enters the exit pupil.

7. The eyepiece optical system according to any one of claims 1 to 6, characterized in that the eyepiece optical system includes a plurality of lenses.

8. The plurality of lenses include a first lens and a second lens bonded to the side of the first lens facing the image display element. The eyepiece optical system according to claim 7, characterized in that the outer diameter of the first lens is larger than the outer diameter of the second lens.

9. The eyepiece optical system according to any one of claims 1 to 8, characterized in that the eyepiece optical system includes a polarizing plate and a semi-transparent reflective element.

10. The eyepiece optical system according to any one of claims 1 to 9, further comprising a second polarizing plate.

11. The first polarizer and the first phase plate have a non-circular first shape, and the second phase plate and the polarization separation element have a non-circular second shape different from the first shape. The eyepiece optical system according to claim 10, characterized in that the first shape and the second shape have shapes for determining the phase between the first shape and the second shape.

12. An eyepiece optical system according to any one of claims 1 to 11, An image display device characterized by having an image display element.

13. The image display device according to claim 12, further comprising an interpupillary distance adjustment mechanism that moves the eyepiece optical system and the image display element according to the interpupillary distance of the observer.

Images