Image display device
The image display device addresses glasses ghosting by using a polarized eyepiece optical system with tailored polarization characteristics for visible and infrared wavelengths, enhancing detection accuracy and image contrast for eyeglass wearers.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- CANON KK
- Filing Date
- 2024-12-19
- Publication Date
- 2026-07-01
Smart Images
Figure 2026109395000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an image display device suitable for a head-mounted display or the like for magnifying and observing an image on an image display element through an eyepiece optical system.
Background Art
[0002] In recent years, in a head-mounted display having a function of detecting an observer's line of sight, a configuration has been proposed in which a part of the optical path of an eyepiece optical system and an imaging optical system for detecting the observer's line of sight is made common for miniaturization (see Patent Documents 1 and 2).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0004] When an observer wears glasses, the detection accuracy of the observer's line of sight may decrease due to glasses ghosts generated by multiple reflections between the glasses and the eyepiece optical system.
[0005] An object of the present invention is to provide an image display device that is advantageous in reducing glasses ghosts generated when an observer wears glasses.
Means for Solving the Problems
[0006] An image display device as one aspect of the present invention comprises an eyepiece optical system that guides light emitted from an image display element to the observer's eye, a light source for illuminating the eye, and an imaging unit for imaging the eye, wherein the eyepiece optical system comprises a lens and a first absorbing polarizer disposed between the lens and the eye and transmitting linearly polarized light in a first direction, and the imaging unit images the eye using the light transmitted through the lens, and the light emitted from the light source and guided to the eye is linearly polarized light in the first direction. [Effects of the Invention]
[0007] According to the present invention, it is possible to provide an image display device that is advantageous in that it reduces glasses ghosting that occurs when the observer is wearing glasses. [Brief explanation of the drawing]
[0008] [Figure 1] This is an external view of the image display device according to the first embodiment. [Figure 2] This is an explanatory diagram of the image display device according to the first embodiment. [Figure 3] This is an explanatory diagram of the eyepiece optical system of the first embodiment. [Figure 4] This is an explanatory diagram of the eyepiece optical system of the first embodiment. [Figure 5] This is an explanatory diagram of the optical path of the imaging optical system in the first embodiment. [Figure 6] This is an explanatory diagram of the optical path of the imaging optical system in the first embodiment. [Figure 7] This is an explanatory diagram of the spectacle ghost optical path of the imaging optical system of the first embodiment. [Figure 8] This is an explanatory diagram of the spectral characteristics of the polarizing element according to the first embodiment. [Figure 9] This is an explanatory diagram of the spectral characteristics of the polarizing element according to the first embodiment. [Figure 10] This is an explanatory diagram illustrating the countermeasures against spectacle ghosting in the imaging optical system of the first embodiment. [Figure 11] This is an explanatory diagram illustrating the countermeasures against spectacle ghosting in the imaging optical system of the first embodiment. [Figure 12]It is an explanatory diagram of the optical path of the imaging optical system according to the first embodiment. [Figure 13] It is an explanatory diagram of the image display device according to the second embodiment. [Figure 14] It is an explanatory diagram of the eyepiece optical system according to the second embodiment. [Figure 15] It is an explanatory diagram of the optical path of the imaging optical system according to the second embodiment. [Figure 16] It is an explanatory diagram of the optical path of the imaging optical system according to the second embodiment. [Figure 17] It is an explanatory diagram of the image display device according to the third embodiment. [Figure 18] It is an explanatory diagram of the eyepiece optical system according to the third embodiment. [Figure 19] It is an explanatory diagram of the optical path of the imaging optical system according to the third embodiment. [Figure 20] It is an explanatory diagram of the optical path of the imaging optical system according to the third embodiment. [Figure 21] It is an explanatory diagram of the eyeglass ghost optical path of the imaging optical system according to the third embodiment. [Figure 22] It is an explanatory diagram of the image display device according to the fourth embodiment. [Figure 23] It is an explanatory diagram of the optical path of the imaging optical system according to the fourth embodiment. [Figure 24] It is an explanatory diagram of the optical path of the imaging optical system according to the fourth embodiment. <所望の [Figure 25] It is an explanatory diagram of the eyeglass ghost countermeasure of the imaging optical system according to the fourth embodiment.
Embodiments for Carrying Out the Invention
[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and redundant descriptions are omitted.
[0010] In each embodiment, since the optical systems corresponding to the left and right eyes have the same configuration, the optical system for the right eye will be described as an example, and the description of the optical system for the left eye will be omitted. [First Embodiment] Figure 1 is an external view of a head-mounted display (HMD) 101, which is an example of an image display device (image observation device) in this embodiment. Figure 2 is an explanatory diagram of the HMD 101.
[0011] The HMD101 includes lenses 104, 105, 106, and 107, a right-eye image display element 108, a left-eye image display element 109, a right-eye imaging unit 116, a right-eye light source 117, a left-eye imaging unit 118, and a left-eye light source 119. Lenses 104 and 105 constitute the right-eye eyepiece optical system, and lenses 106 and 107 constitute the left-eye eyepiece optical system. The right-eye image display element 108 and the left-eye image display element 109 are, for example, organic EL displays. The right-eye imaging unit 116 and the left-eye imaging unit 118 are infrared cameras including image sensors, respectively.
[0012] The right 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 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 eyepiece optical system and the left eyepiece optical system is 12 mm, the horizontal display field of view is 45°, the vertical display field of view is 34°, and the diagonal display field of view is 54°. The distance between the HMD 101 and the observer's eye (eye relief) E1 is 18 mm.
[0013] Since the HMD101 is a head-mounted image display device, it is desirable that it be lightweight. Therefore, it is desirable that the lenses constituting the eyepiece optical system be made of resin, which has a lower specific gravity than glass. In this embodiment, lenses 104 and 106 are made of resin, and the aberration correction effect is enhanced by making them aspherical lenses with a plano-convex shape. Lenses 105 and 107 are double-sided aspherical lenses made of resin. However, since lenses 105 and 107 have a small external size and the impact of weight increase is small, they may be made of glass instead of resin. Because the birefringence of glass lenses is very small, high-quality image observation is possible.
[0014] The eyepiece optical system of this embodiment is an optical system that folds the optical path using polarization, and the optical path will be explained using the right eyepiece optical system. Figure 3 is an explanatory diagram of the right eyepiece optical system. Between the right eye image display element 108 and the lens 105, a polarizer (second absorbing polarizer) 110 and a phase plate 111 are arranged in order from the right eye image display element 108 side. A half mirror 112 is deposited on the surface of the lens 104 on the lens 105 side. The surface on which the half mirror 112 is deposited acts as a transmission and reflection surface. Between the lens 104 and the right eye 102, a phase plate 113, a polarizing beam splitter (PBS) 114 which is a reflective polarizer, and a polarizer (first absorbing polarizer) 115 which is an absorbing polarizer are arranged in order from the right eye image display element 108 side. The PBS 114 transmits linearly polarized light in a first direction and reflects linearly polarized light in a second direction perpendicular to the first direction. The phase plate 113, PBS 114, and polarizer 115 have a planar shape. Phase plates 111 and 113 are phase plates with a phase difference of λ / 4. The polarization direction of the polarization transmitted through polarizer 110 and the slow axis of phase plate 111 are tilted at 45°. The polarization direction of the polarization transmitted through polarizer 110 and the slow axis of phase plate 113 are tilted at -45°. The polarization direction of the polarization transmitted through polarizer 110 and the polarization directions of the polarization transmitted through PBS 114 and polarizer 115 are orthogonal.
[0015] In this configuration, light emitted from the right eye image display element 108 passes through the polarizing plate 110 to become linearly polarized light, and then passes through the phase plate 111 to become circularly polarized light. This circularly polarized light passes through the half mirror 112 and then through the phase plate 113 to become linearly polarized light. Since the polarization direction of this linearly polarized light is perpendicular to the polarization direction of the polarization transmitted by PBS 114, it is reflected by PBS 114 and passes through the phase plate 113 to become circularly polarized light. This circularly polarized light is reflected by the half mirror 112 and passes through the phase plate 113 to become linearly polarized light. Since the polarization direction of this linearly polarized light coincides with the polarization direction transmitted by PBS 114, it passes through PBS 114 and the polarizing plate 115 and is guided to the right eye 102.
[0016] In this embodiment, by placing a polarizing plate between the PBS and the observer's eye, ghosting from ambient light can be reduced, thereby improving the contrast of the observed image.
[0017] In this embodiment, by using an optical system that folds the optical path using polarization, a thin design and a shorter focal length for the eyepiece optical system can be achieved, enabling wide-angle image observation.
[0018] As shown in Figure 4, the exit pupil of the eyepiece optical system is positioned at 28 mm, which is the sum of the eye relief of 18 mm and the rotational radius of the eyeball of 10 mm, with an exit pupil diameter of 6 mm. With this configuration, even when the eyeball rotates to observe up, down, left, or right, light in that direction enters the eyeball. The HMD101 is a head-mounted image display device, and it is desirable that the eye relief be 15 mm or more so that observers wearing glasses can also wear it. Furthermore, if the eye relief becomes too long, the outer diameter of the lens will increase, and the HMD101 will also become larger, so it is desirable that the eye relief be 25 mm or less.
[0019] The surface on which the half-mirror 112 is deposited has a convex shape toward the right-eye image display element 108. By depositing the half-mirror 112 on the convex surface, a wide field of view can be achieved while making the optical system thinner. Furthermore, by making the convex surface on which the half-mirror 112 is deposited aspherical, the aberration correction effect is enhanced.
[0020] The imaging optical system of this embodiment includes a light source that illuminates the observer's eye and an imaging unit that images the observer's eye, and is an optical system that detects the line of sight by imaging the observer's eye. Its optical path will be described below. Figure 5 is an explanatory diagram of the optical path of the imaging optical system of this embodiment.
[0021] The right eye light source 117 is an infrared light source that emits light in a wavelength range (second wavelength range) longer than the visible light wavelength range (first wavelength range). Light from the right eye light source 117 passes through the half mirror 112 and enters the lens 104, then passes through the phase plate 113, PBS 114, and polarizer 115 to illuminate the right eye 102. Light from the right eye 102 passes through the polarizer 115, PBS 114, and phase plate 113 and enters the lens 104, then passes through the half mirror 112 and enters the right eye imaging unit 116. The right eye imaging unit 116 uses the received light to acquire an image of the right eye 102. By making the optical path of the imaging optical system that detects the observer's line of sight common with the eyepiece optical system in this way, the optical system can be made smaller. Specifically, the visible light from the right eye image display element 108 and the infrared light from the right eye light source 117 share the half mirror 112, lens 104, phase plate 113, PBS 114, and polarizer 115. However, the infrared light from the right eye light source 117 does not pass through the lens 105, polarizer 110, and phase plate 111, and therefore does not share them.
[0022] If the observer is wearing glasses 120, the optical path of the observation optical system will be as shown in Figure 6, but as shown in Figure 7(a), multiple reflections occur between the glasses 120 and the half mirror 112, resulting in glasses ghosting incident on the right eye imaging unit 116. Also, as shown in Figure 7(b), multiple reflections occur between the glasses 120 and the polarizer 115 and PBS 114, resulting in glasses ghosting incident on the right eye imaging unit 116.
[0023] In an optical system that folds the optical path using polarization that does not detect the observer's line of sight, the image display element emits light in the visible light wavelength range of 400 nm to 750 nm, so the polarizer and PBS used are those that only support visible light. When a polarizer that only supports visible light is used when detecting the observer's line of sight using infrared light, as in this embodiment, it transmits infrared light regardless of the polarization direction, as shown in Figure 8(a). Also, with a PBS that only supports visible light, as shown in Figure 8(b), the transmittance of linearly polarized light that is reflected by visible light increases with infrared light, and the transmittance becomes 80% or more. Therefore, the infrared light emitted from the right eye light source 117 passes through the PBS 114 and polarizer 115 without being polarized.
[0024] However, the polarizer and PBS have high transmittance to unpolarized infrared light, and the infrared light reflected by the glasses 120 and half mirror 112 passes through the polarizer 115 and PBS 114, resulting in the glasses ghost path shown in Figure 7(a).
[0025] Furthermore, linearly polarized light, which is absorbed by the polarizer 115 and reflected by the PBS 114 in the case of visible light, is transmitted through both the polarizer 115 and the PBS 114 in the case of infrared light. Therefore, in the spectacle ghost optical path shown in Figure 7(b), linearly polarized infrared light, which is absorbed by the polarizer 115 and reflected by the PBS 114 in the case of visible light, is reflected once by the spectacle 120 and transmitted through the polarizer 115, and the reflectivity of the PBS 114 is lower than that of visible light. However, it is reflected with a reflectivity higher than that of the surface reflection of the polarizer 115 and is transmitted through the polarizer 115. Subsequently, it is reflected a second time by the spectacle 120 and transmitted through the polarizer 115 and the PBS 114, causing spectacle ghosting in the image acquired by the right eye imaging unit 116.
[0026] Therefore, in this embodiment, PBS114 has polarization characteristics only for visible light as shown in Figure 8(b), but the polarizer 115 is made to have the same polarization characteristics as visible light at wavelengths in the infrared region from the right eye light source 117 as shown in Figure 9(a). Specifically, the transmittance of linearly polarized light in the direction of reflection in PBS114 is set to 10% or less for visible light and 70% or more for wavelengths in the infrared region, and the transmittance of linearly polarized light in the direction perpendicular to the direction of transmission in the polarizer 115 is set to 10% or less for visible light and 10% or less for wavelengths in the infrared region.
[0027] With this configuration, infrared light emitted from the right eye light source 117 passes through the polarizer 115 to become linearly polarized and is reflected by the eyeglasses 120. The light reflected by the eyeglasses 120 passes through the polarizer 115 and PBS 114, passes through the phase plate 113 to become circularly polarized and enters the lens 104. This circularly polarized light is reflected by the half mirror 112, passes through the phase plate 113, and becomes linearly polarized. Because the direction of polarization of this linearly polarized light is rotated by 90° from the previous linearly polarized light, it passes through PBS 114 but is absorbed by the polarizer 115. Therefore, as shown in Figure 10(a), the eyeglass ghosting caused by multiple reflections between the eyeglasses 120 and the half mirror 112 can be reduced.
[0028] Furthermore, the light reflected by the glasses 120 passes through the polarizer 115 and PBS 114, but it is linearly polarized in the direction of transmission through PBS 114 and is not reflected by PBS 114. Therefore, as shown in Figure 10(b), the glasses ghost that occurs due to multiple reflections between the glasses 120 and PBS 114 can be reduced.
[0029] Furthermore, if it is difficult to achieve the same polarization characteristics for infrared wavelengths as for visible light with a single polarizing plate 115, a visible light polarizing plate and an infrared polarizing plate may be laminated together.
[0030] In this embodiment, the polarizer 115 is configured to have the same polarization characteristics as visible light at infrared wavelengths from the right eye light source 117, thereby preventing ghosting of eyeglasses. However, the present invention is not limited to this. As shown in Figure 8(a), the polarizer 115 has polarization characteristics only for visible light, but the PBS 114 may be configured to have the same polarization characteristics as visible light at infrared wavelengths, as shown in Figure 9(b). Specifically, the transmittance of linearly polarized light in the direction perpendicular to the transmission direction in the polarizer 115 is set to 10% or less for visible light and 70% or more for infrared wavelengths, and the transmittance of linearly polarized light in the reflection direction in the PBS 114 is set to 10% or less for visible light and 10% or less for infrared wavelengths.
[0031] With this configuration, infrared light emitted from the right eye light source 117 passes through the PBS 114 to become linearly polarized, passes through the polarizer 115, and is reflected by the glasses 120. The light reflected by the glasses 120 passes through the polarizer 115 and PBS 114, passes through the phase plate 113 to become circularly polarized, and enters the lens 104. This circularly polarized light is reflected by the half mirror 112, passes through the phase plate 113 to become linearly polarized. This linear light is reflected by the PBS 114 because the direction of polarization is rotated by 90° from the linearly polarized light mentioned earlier. Therefore, as shown in Figure 11(a), the glasses ghost that occurs when the light is reflected once by the half mirror 112 and twice by the glasses 120 can be reduced. Although there is an optical path where the light is reflected twice by the half mirror 112, the number of reflections increases, so the glasses ghost light becomes dimmer.
[0032] Furthermore, the light reflected by the glasses 120 passes through the polarizer 115 and PBS 114, but it is linearly polarized in the direction of transmission through PBS 114 and is not reflected by PBS 114. Therefore, as shown in Figure 11(b), the glasses ghost that occurs due to multiple reflections between the glasses 120 and PBS 114 can be reduced.
[0033] In this way, by making either the PBS 114 or the polarizer 115 have polarization characteristics similar to visible light at wavelengths in the infrared region from the right eye light source 117, the ghosting of glasses can be reduced.
[0034] In this embodiment, one of the PBS 114 and the polarizer 115 is polarized to have the same polarization characteristics as visible light at wavelengths in the infrared region from the right eye light source 117, while the other is polarized to have the same polarization characteristics as visible light only. However, the present invention is not limited to this. Both the PBS 114 and the polarizer 115 may be polarized to have the same polarization characteristics as visible light at wavelengths in the infrared region from the right eye light source 117.
[0035] Furthermore, by making the light emitted from the right eye light source 117 and guided to the right eye 102 linearly polarized in the direction through which the PBS 114 and polarizer 115 pass, it is possible to reduce the glasses ghost that occurs due to multiple reflections between the glasses 120 and the PBS 114. In this embodiment, at least one of the PBS 114 and the polarizer 115 is made to have polarization characteristics similar to visible light at wavelengths in the infrared region from the right eye light source 117. This changes the light emitted from the right eye light source 117 to linearly polarized in the direction through which the PBS 114 and polarizer 115 pass. However, the present invention is not limited thereto.
[0036] For example, the light source 117 for the right eye may be positioned to directly illuminate the observer's eye. In this case, the light source 117 for the right eye should be configured to emit linearly polarized light in the direction through which the PBS 114 and polarizer 115 pass. Alternatively, a polarizer may be provided to change the light emitted from the light source 117 for the right eye to linearly polarized light in the direction through which the PBS 114 and polarizer 115 pass. With such a configuration, it is possible to reduce the glasses ghost caused by multiple reflections between the glasses 120 and PBS 114, even without making at least one of the PBS 114 and polarizer 115 have the same polarization characteristics as visible light at wavelengths in the infrared region from the light source 117 for the right eye. Furthermore, it is possible to reduce the glasses ghost caused by multiple reflections between the glasses 120 and half mirror 112 compared to when unpolarized light is irradiated.
[0037] Furthermore, the light source 117 for the right eye may be configured to emit circularly polarized light such that the light transmitted through the phase plate 213 is linearly polarized in the direction through which the PBS 114 and polarizer 115 pass. Even with such a configuration, it is possible to reduce the glasses ghost caused by multiple reflections between the glasses 120 and PBS 114 without having to make at least one of the PBS 114 and polarizer 115 have the same polarization characteristics as visible light at wavelengths in the infrared region from the light source 117 for the right eye. In addition, it is possible to reduce the glasses ghost caused by multiple reflections between the glasses 120 and half mirror 112 compared to when unpolarized light is irradiated.
[0038] Alternatively, a polarizer and a phase plate corresponding to wavelengths in the infrared region may be placed between the right eye light source 117 and the lens 104, and the infrared light emitted from the right eye light source 117 may be linearly polarized after passing through the phase plate 113 and PBS 114. This makes it possible to suppress the reflection of infrared light emitted from the right eye light source 117 by the PBS 114, which can cause ghosting.
[0039] Furthermore, since reflected light from the surface of the polarizer 115 is also generated in the optical path of the spectacle ghost shown in Figure 7(b), an anti-reflective coating corresponding to the infrared and visible light regions may be deposited on the surface of the polarizer 115. This can further reduce spectacle ghosting.
[0040] Furthermore, it is desirable that the phase plate 113 has the same elliptic characteristics in the infrared region as in the visible light region in order to reduce the glasses ghost shown in Figure 7(a). Specifically, it is desirable that the ellipticity of the phase plate 113 be 70% or more in the visible light region and 70% or more in the infrared region, and more preferably 80% or more in both. The polarizer 110 and phase plate 111 are not in the optical path of the infrared light from the right eye light source 117, so it is sufficient that they only correspond to visible light.
[0041] Furthermore, the central wavelength of the right eye light source 117 is 950 nm, and it is desirable that the wavelength range of the infrared light used to detect the line of sight be between 800 nm and 1200 nm. It is even more desirable that the wavelength be above 900 nm so that the observer is not bothered by the light source used to detect the line of sight. Also, wavelengths above 1200 nm are undesirable because they reduce the sensitivity of the image sensor.
[0042] As shown in Figure 12(a), a right-eye light source 121 may be additionally placed outside the eyepiece optical system to increase the amount of light illuminating the observer's eye. In this case, spectacle ghosting will occur, similar to infrared light from the right-eye light source 117, but spectacle ghosting can be reduced by making at least one of the PBS 114 and the polarizer 115 have polarization characteristics similar to visible light at wavelengths in the infrared region from the right-eye light source 117.
[0043] Alternatively, after the light source 121 for the right eye emits light, the polarizer 122 corresponding to the wavelength in the infrared region may be positioned as shown in Figure 12(b) so that the PBS 114 and polarizer 115 become linearly polarized in the direction of visible light transmission. By doing so, it is possible to suppress the reflection of infrared light emitted from the light source 121 for the right eye by the PBS 114, which can cause ghosting.
[0044] In this embodiment, the observer's eye-facing surface of the lens 104, on which the phase plate 113 and PBS 114 are formed, is flat. This makes it possible to achieve both a longer eye relief and a thinner optical system. If the observer's eye-facing surface of the lens 104 is concave toward the observer's eyeball, the lens becomes thicker to ensure eye relief at the periphery. Conversely, if it is convex, the lens becomes thicker to ensure the thickness of the lens edge. Therefore, it is desirable that the lens 104 be a plano-convex lens.
[0045] In this embodiment, the phase plates 111 and 113 are phase plates with a phase difference of λ / 4, but the phase difference may be shifted from λ / 4 to cancel the birefringence of the lenses 104 and 105. In this case, it is desirable that the sum of the phase differences of lens 104 and phase plate 113 be 3λ / 20 or more and 7λ / 20 or less. It is also desirable that the sum of the phase differences of lens 105 and phase plate 111 be 3λ / 20 or more and 7λ / 20 or less. If it falls outside this range, the intensity of ghost light will increase, making natural observation impossible.
[0046] In this embodiment, the image display element is an organic EL that emits unpolarized light, but it may also be configured to emit linearly polarized light as a liquid crystal display. This eliminates the need to provide a polarizing plate 110 on the image display element side, allowing for a thinner design. [Second Embodiment] Figure 13 is an explanatory diagram of a head-mounted display (HMD) 201, which is an example of an image display device (image observation device) in this embodiment.
[0047] The HMD201 includes lenses 204, 205, 206, 207, a right-eye image display element 208, a left-eye image display element 209, a right-eye imaging unit 216, a right-eye light source 217, a left-eye imaging unit 218, a left-eye light source 219, and optical elements 220, 221. Lenses 204 and 205 are joined to form the right-eye eyepiece optical system, and lenses 206 and 207 are joined to form the left-eye eyepiece optical system. The right-eye image display elements 208 and 209 are, for example, organic EL displays. The right-eye imaging unit 216 is positioned outside the optically effective region of lens 205 with respect to light from the right-eye image display element 208. The left-eye imaging unit 218 is positioned outside the optically effective region of lens 207 with respect to light from the left-eye image display element 209. The right-eye imaging unit 216 and the left-eye imaging unit 218 are infrared cameras, each containing an image sensor. The optical element 220 is bonded to the lens 205 to improve the optical performance of the right-eye imaging unit 216. The optical element 221 is bonded to the lens 207 to improve the optical performance of the left-eye imaging unit 218.
[0048] The right 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 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 F2 of the right eyepiece optical system and the left eyepiece optical system is 13 mm, the horizontal display angle of view is 60°, the vertical display angle of view is 60°, the diagonal display angle of view is 78°, and the eye relief E2 is 20 mm.
[0049] Since the HMD201 is a head-mounted image display device, it is desirable that it be lightweight. Therefore, it is desirable that the lenses constituting the eyepiece optical system be made of resin, which has a lower specific gravity than glass. In this embodiment, lenses 204, 205, 206, and 207 are made of resin and are aspherical lenses to enhance the aberration correction effect.
[0050] The eyepiece optical system of this embodiment is an optical system that folds the optical path using polarization, and the optical path will be explained using the right eyepiece optical system. Figure 14 is an explanatory diagram of the right eyepiece optical system. Between the right eye image display element 208 and the lens 205, a polarizer (second absorbing polarizer) 210 and a phase plate 211 are arranged in order from the right eye image display element 208 side. A half mirror 212 is deposited on the surface of the lens 204 that faces the lens 205. The surface on which the half mirror 212 is deposited acts as a transmission and reflection surface. Between the lens 204 and the right eye 202, a phase plate 213, a polarizing beam splitter (PBS) 214 which is a reflective polarizer, and a polarizer (first absorbing polarizer) 215 which is an absorbing polarizer are arranged in order from the right eye image display element 208 side. PBS214 transmits linearly polarized light in a first direction and reflects linearly polarized light in a second direction perpendicular to the first direction. Phase plates 213, PBS214, and polarizer 215 have a planar shape. Phase plates 211 and 213 are phase plates with a phase difference of λ / 4. The polarization direction transmitted by polarizer 210 and the slow axis of phase plate 211 are tilted at 45°. The polarization direction transmitted by polarizer 210 and the slow axis of phase plate 213 are tilted at -45°. The polarization direction transmitted by polarizer 210 and the polarization directions transmitted by PBS214 and polarizer 215 are perpendicular.
[0051] In this configuration, light emitted from the right eye image display element 208 passes through the polarizing plate 210 to become linearly polarized light, and then passes through the phase plate 211 to become circularly polarized light. This circularly polarized light passes through the half mirror 212 and then through the phase plate 213 to become linearly polarized light. Since the polarization direction of this linearly polarized light is perpendicular to the polarization direction of the polarization transmitted by PBS 214, it is reflected by PBS 214 and passes through the phase plate 213 to become circularly polarized light. This circularly polarized light is reflected by the half mirror 212 and passes through the phase plate 213 to become linearly polarized light. Since the polarization direction of this linearly polarized light coincides with the polarization direction transmitted by PBS 214, it passes through PBS 214 and the polarizing plate 215 and is guided to the right eye 202.
[0052] In this embodiment, by placing a polarizing plate between the PBS and the observer's eye, ghosting from ambient light can be reduced, thereby improving the contrast of the observed image.
[0053] In this embodiment, by using an optical system that folds the optical path using polarization, a thin design and a shorter focal length for the eyepiece optical system can be achieved, enabling wide-angle image observation.
[0054] The exit pupil of the eyepiece optical system is positioned at 30mm, which is the sum of the eye relief of 20mm and the rotation radius of the eyeball of 10mm, with an exit pupil diameter of 6mm. With this configuration, even when the eyeball rotates to observe up, down, left, or right, light in that direction enters the eyeball. The HMD201 is a head-mounted image display device, and it is desirable that the eye relief be 15mm or more so that observers wearing glasses can also wear it. Furthermore, since a longer eye relief increases the outer diameter of the lens and thus the size of the HMD201, it is desirable that the eye relief be 25mm or less.
[0055] The surface on which the half-mirror 212 is deposited has a convex shape toward the right-eye image display element 208. By depositing the half-mirror 212 on the convex surface, a wide field of view can be achieved while making the optical system thinner. Furthermore, by making the convex surface on which the half-mirror 212 is deposited aspherical, the aberration correction effect is enhanced.
[0056] The imaging optical system of this embodiment includes a light source that illuminates the observer's eye and an imaging unit that images the observer's eye, and is an optical system that detects the line of sight by photographing the observer's eye. Its optical path will be described below. Figure 15 is an explanatory diagram of the optical path of the imaging optical system of this embodiment.
[0057] The right eye light source 217 is an infrared light source that emits light in a wavelength range (second wavelength range) longer than the visible light wavelength range (first wavelength range). Light from the right eye light source 117 passes through the lens 205 and half mirror 212 and enters the lens 204, then passes through the phase plate 213, PBS 214, and polarizer 215 to illuminate the right eye 202. Light from the right eye 202 passes through the polarizer 215, PBS 214, and phase plate 213 and enters the lens 204, then passes through the half mirror 212 and lens 205 and enters the right eye imaging unit 216. The right eye imaging unit 216 uses the received light to acquire an image of the right eye 202. In this way, by making the optical path of the imaging optical system that detects the observer's line of sight common with the eyepiece optical system, the optical system can be made smaller. Specifically, the visible light from the right eye image display element 208 and the infrared light from the right eye light source 217 share lens 205, half mirror 212, lens 204, phase plate 213, PBS 214, and polarizer 215. However, the infrared light from the right eye light source 217 does not pass through polarizer 210 and phase plate 211 and therefore does not share them.
[0058] If the observer is wearing glasses 222, the optical path of the observation optical system will be as shown in Figure 16, but multiple reflections between the glasses 222 and the half mirror 212 will occur, resulting in glasses ghosting incident on the right eye imaging unit 216. Additionally, multiple reflections between the glasses 222, the polarizer 215 and PBS 214 will occur, resulting in glasses ghosting incident on the right eye imaging unit 216.
[0059] Therefore, in this embodiment, PBS214 has polarization characteristics only for visible light as shown in Figure 8(b), but the polarizer 215 is made to have the same polarization characteristics as visible light at wavelengths in the infrared region from the right eye light source 117. Specifically, the transmittance of linearly polarized light in the direction of reflection in PBS214 is set to 5% or less for visible light and 80% or more for wavelengths in the infrared region, and the transmittance of linearly polarized light in the direction perpendicular to the direction of transmission in the polarizer 215 is set to 5% or less for visible light and 5% or less for wavelengths in the infrared region.
[0060] With this configuration, infrared light emitted from the right eye light source 217 passes through the polarizer 215 to become linearly polarized light, which is then reflected by the eyeglasses 222. The light reflected by the eyeglasses 222 passes through the polarizer 215 and PBS 214, then through the phase plate 213 to become circularly polarized light, which then enters the lens 204. This circularly polarized light is reflected by the half mirror 212 and passes through the phase plate 213 to become linearly polarized light. Because the direction of polarization of this linearly polarized light is rotated by 90° from the previous linearly polarized light, it passes through PBS 214 but is absorbed by the polarizer 215. Therefore, the eyeglass ghosting caused by multiple reflections between the eyeglasses 222 and the half mirror 212 can be reduced.
[0061] Furthermore, the light reflected by the glasses 222 passes through the polarizing plate 215 and PBS 214, but it is linearly polarized in the direction of transmission through PBS 214 and is not reflected by PBS 214. Therefore, it is possible to reduce the glasses ghost that occurs due to multiple reflections between the glasses 222 and PBS 214.
[0062] Furthermore, if it is difficult to achieve the same polarization characteristics for infrared wavelengths as for visible light with a single polarizing plate 215, a visible light polarizing plate and an infrared polarizing plate may be laminated together.
[0063] In this embodiment, the polarizing plate 215 is configured to have the same polarization characteristics as visible light at infrared wavelengths from the right eye light source 217, thereby preventing ghosting of eyeglasses. However, the present invention is not limited to this. As shown in Figure 8(a), the polarizing plate 215 has polarization characteristics only for visible light, but the PBS 214 may be configured to have the same polarization characteristics as visible light at infrared wavelengths. Specifically, the transmittance of linearly polarized light in the direction perpendicular to the transmission direction in the polarizing plate 115 is set to 5% or less for visible light and 80% or more for infrared wavelengths, and the transmittance of linearly polarized light in the reflection direction in the PBS 114 is set to 5% or less for visible light and 5% or less for infrared wavelengths.
[0064] With this configuration, infrared light emitted from the right eye light source 217 passes through the PBS 214 to become linearly polarized, passes through the polarizer 215, and is reflected by the glasses 222. The light reflected by the glasses 222 passes through the polarizer 215 and PBS 214, passes through the phase plate 213 to become circularly polarized, and enters the lens 204. This circularly polarized light is reflected by the half mirror 212, passes through the phase plate 213 to become linearly polarized. This linearly polarized light is reflected by the PBS 214 because its polarization direction is rotated by 90° from the previous linearly polarized light. Therefore, the glasses ghost that occurs due to reflection once by the half mirror 212 and twice by the glasses 222 can be reduced. Although there is an optical path that reflects twice by the half mirror 212, the number of reflections increases, so the glasses ghost light becomes dimmer.
[0065] Furthermore, the light reflected by the glasses 222 passes through the polarizing plate 215 and PBS 214, but it is linearly polarized in the direction of transmission through PBS 214 and is not reflected by PBS 214. Therefore, it is possible to reduce the glasses ghost that occurs due to multiple reflections between the glasses 222 and PBS 214.
[0066] In this way, by making at least one of the PBS214 and the polarizer 215 have polarization characteristics similar to visible light at wavelengths in the infrared region from the right eye light source 217, the ghosting of glasses can be reduced.
[0067] Alternatively, a polarizer and a phase plate corresponding to wavelengths in the infrared region may be placed between the right eye light source 217 and the lens 205, and the infrared light emitted from the right eye light source 217 may be linearly polarized after passing through the phase plate 213 and PBS 214. This can suppress the reflection of infrared light emitted from the right eye light source 217 by PBS 214, which can cause ghosting.
[0068] Furthermore, since reflected light from the surface of the polarizer 215 is also generated in the optical path of the glasses ghost caused by multiple reflections between the glasses 222 and PBS 214, an anti-reflective film corresponding to the infrared and visible light regions may be deposited on the surface of the polarizer 215. This can further reduce the glasses ghost.
[0069] Furthermore, it is desirable that the phase plate 213 has the same elliptic characteristics in the infrared region as it does in the visible light region in order to reduce the glasses ghost caused by multiple reflections between the glasses 222 and the half mirror 212. Specifically, it is desirable that the ellipticity of the phase plate 213 be 70% or more in the visible light region and 70% or more in the infrared region, and preferably 80% or more in both. The polarizer 210 and phase plate 211 are not in the optical path of the infrared light from the right eye light source 217, so they only need to be compatible with visible light.
[0070] Furthermore, the image display element in this embodiment emits light in the visible light wavelength range of 430 to 700 nm, the central wavelength of the right eye light source 217 is 900 nm, and it is desirable that the wavelength of the infrared light used to detect the line of sight be 800 nm or higher. It is even more desirable that it be 900 nm or higher so that the observer is not bothered by the light source used to detect the line of sight.
[0071] Furthermore, in this embodiment, the optical element 220 is bonded to the lens 205 in order to improve the optical performance of the imaging optical system. However, since infrared light may be reflected and scattered on the sides of the optical element 220, causing ghosting, the optical element 220 may be coated with black paint to prevent reflection. In this case, it is desirable that the black paint has the property of absorbing infrared light from the right eye light source 217.
[0072] In this embodiment, the observer's eye-facing surface of the lens 204, on which the phase plate 213, PBS 214, and polarizer 215 are formed, is made flat. This makes it possible to achieve both a longer eye relief and a thinner optical system. For this reason, it is desirable that the lens 204 be a plano-convex lens. [Third Embodiment] Figure 17 is an explanatory diagram of a head-mounted display (HMD) 301, which is an example of an image display device (image observation device) in this embodiment.
[0073] The HMD301 includes lenses 304, 305, 306, 307, a right-eye image display element 308, a left-eye image display element 309, a right-eye imaging unit 316, a right-eye light source 317, a left-eye imaging unit 318, a left-eye light source 319, and optical elements 320, 221. Lenses 304 and 305 are joined to form the right-eye eyepiece optical system, and lenses 306 and 307 are joined to form the left-eye eyepiece optical system. The right-eye image display element 308 and the left-eye image display element 309 are, for example, organic EL displays. The right-eye imaging unit 316 is positioned outside the optically effective region of lens 305 with respect to light from the right-eye image display element 308. The left-eye imaging unit 318 is positioned outside the optically effective region of lens 307 with respect to light from the left-eye image display element 309. The right-eye imaging unit 316 and the left-eye imaging unit 318 are infrared cameras, each containing an image sensor. The optical element 320 is bonded to the lens 305 to improve the optical performance of the right-eye imaging unit 316. The optical element 321 is bonded to the lens 307 to improve the optical performance of the left-eye imaging unit 318.
[0074] The right 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 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.
[0075] The eyepiece optical system of this embodiment is an optical system that folds the optical path using polarization, and the optical path will be explained using the right eyepiece optical system. Figure 18 is an explanatory diagram of the right eyepiece optical system. A polarizer (second absorbing polarizer) 310 is placed between the right eye image display element 308 and the lens 305. A polarizing beam splitter (PBS) 311 and a phase plate 312 are placed between the lenses 304 and 305, in order from the right eye image display element 308 side. The PBS 311 transmits linearly polarized light in a first direction and reflects linearly polarized light in a second direction perpendicular to the first direction. Between the lens 304 and the right eye 302, a half mirror 313, a phase plate 314, and a polarizer (first absorbing polarizer) 315, which is an absorbing polarizer, are placed in order from the right eye image display element 308 side. The surface on which the half mirror 313 is deposited acts as a transmission and reflection surface. The half-mirror 313, the phase plate 314, and the polarizer 315 have a planar shape. Phase plates 312 and 314 are phase plates with a phase difference of λ / 4. The polarization direction transmitted by polarizer 310 and the polarization direction transmitted by PBS 311 are the same. The polarization direction transmitted by polarizer 310 and the slow axis of phase plate 312 are tilted at 45°. The polarization direction transmitted by polarizer 310 and the slow axis of phase plate 314 are tilted at -45°. The polarization direction transmitted by polarizer 310 and the polarization direction transmitted by polarizer 315 are orthogonal.
[0076] In this configuration, light emitted from the right eye image display element 308 passes through the polarizing plate 310 to become linearly polarized, then passes through the PBS 311 and the phase plate 312 to become circularly polarized. This circularly polarized light is reflected by the half mirror 313 and passes through the phase plate 312 to become linearly polarized. Since the polarization direction of this linearly polarized light is perpendicular to the polarization direction transmitted by the PBS 311, it is reflected by the PBS 311 and passes through the phase plate 312 to become circularly polarized. This circularly polarized light passes through the half mirror 313 and the phase plate 314 to become linearly polarized. Since the polarization direction of this linearly polarized light coincides with the direction transmitted through the polarizing plate 315, it is guided to the observer's right eye 202.
[0077] In this embodiment, by using an optical system that folds the optical path using polarization, a thin design and a shorter focal length for the eyepiece optical system can be achieved, enabling wide-angle image observation.
[0078] The surface on which PBS311 is formed has a convex shape toward the right-eye image display element 308. By forming PBS311 on a convex surface, a wide field of view can be achieved while making the optical system thinner. Furthermore, by making the convex surface on which PBS311 is formed an aspherical shape, the aberration correction effect is enhanced.
[0079] The imaging optical system of this embodiment includes a light source that illuminates the observer's eye and an imaging unit that images the observer's eye, and is an optical system that detects the line of sight by photographing the observer's eye. Its optical path will be described below. Figure 19 is an explanatory diagram of the optical path of the imaging optical system of this embodiment.
[0080] The right eye light source 317 is an infrared light source that emits light in a wavelength range (second wavelength range) longer than the visible light wavelength range (first wavelength range). Light from the right eye light source 317 passes through lens 305, PBS 311, and phase plate 312, enters lens 304, passes through half mirror 313, phase plate 314, and polarizer 315 to illuminate the right eye 302. Light from the right eye 302 passes through polarizer 315, phase plate 314, and half mirror 313, enters lens 304, passes through phase plate 312, PBS 311, and lens 305, and enters the right eye imaging unit 316. The right eye imaging unit 316 acquires an image of the right eye 302 using the received light. By making the optical path of the imaging optical system that detects the observer's line of sight common with the eyepiece optical system in this way, the optical system can be made smaller. Specifically, the visible light from the right eye image display element 308 and the infrared light from the right eye light source 317 share the lens 305, PBS 311, phase plate 312, lens 304, half mirror 313, phase plate 314, and polarizer 315. However, the infrared light from the right eye light source 317 does not pass through the polarizer 310 and is not shared with it.
[0081] If the observer is wearing glasses 322, the optical path of the observation optical system will be as shown in Figure 20, but as shown in Figure 21, multiple reflections occur between the glasses 322 and the half mirror 313, resulting in glasses ghosting incident on the right eye imaging unit 316. Additionally, multiple reflections occur between the glasses 222, the polarizer 215 and PBS 214, resulting in glasses ghosting incident on the right eye imaging unit 316.
[0082] Therefore, in this embodiment, PBS311 has polarization characteristics only for visible light as shown in Figure 8(b), but the polarizer 315 is made to have the same polarization characteristics as visible light even at wavelengths in the infrared region from the right eye light source 317. Specifically, the transmittance of linearly polarized light in the direction of reflection in PBS311 is set to 10% or less for visible light and 70% or more for wavelengths in the infrared region, and the transmittance of linearly polarized light in the direction perpendicular to the direction of transmission in the polarizer 315 is set to 10% or less for visible light and 10% or less for wavelengths in the infrared region.
[0083] With this configuration, infrared light emitted from the right eye light source 317 passes through the polarizing plate 315 to become linearly polarized and is reflected by the eyeglasses 322. The light reflected by the eyeglasses 322 passes through the polarizing plate 315 and then through the phase plate 314 to become circularly polarized and is reflected by the half mirror 313. This circularly polarized light passes through the phase plate 314 to become linearly polarized. This linearly polarized light has a polarization direction rotated by 90° from the previous linearly polarized light and is therefore absorbed by the polarizing plate 315. As a result, the eyeglass ghost that occurs due to multiple reflections between the eyeglasses 322 and the half mirror 313 can be reduced.
[0084] Furthermore, if it is difficult to achieve the same polarization characteristics for infrared wavelengths as for visible light with a single polarizing plate 315, a visible light polarizing plate and an infrared polarizing plate may be laminated together.
[0085] In this way, by making the polarizing plate 315 have polarization characteristics similar to visible light at wavelengths in the infrared region from the right eye light source 317, the ghosting of glasses can be reduced.
[0086] Furthermore, since reflected light is also generated on the surface of the polarizing plate 315, an anti-reflective coating corresponding to the infrared and visible light regions may be deposited on the surface of the polarizing plate 315. This can further reduce the ghosting of eyeglasses.
[0087] Furthermore, it is desirable that the phase plate 314 has the same elliptic characteristics in the infrared region as it does in the visible light region in order to reduce the glasses ghost that occurs due to multiple reflections between the glasses 322 and the half mirror 313. Specifically, it is desirable that the ellipticity of the phase plate 314 be 70% or more in the visible light region and 70% or more in the infrared region, and preferably 80% or more in both. The polarizer 310 is not in the optical path of the infrared light from the right eye light source 317, so it is sufficient to have one that is compatible only with visible light. Also, the phase plate 312 is not in the optical path of the multiple reflections between the glasses 322 and the half mirror 313, so it is sufficient to have one that is compatible only with visible light.
[0088] Furthermore, the image display element of this embodiment emits light in the visible light wavelength range of 430 to 700 nm, the central wavelength of the right eye light source 317 is 860 nm, and it is desirable that the wavelength of the infrared light used to detect the line of sight be 800 nm or higher. [Fourth Embodiment] Figure 22 is an explanatory diagram of a head-mounted display (HMD) 401, which is an example of an image display device (image observation device) in this embodiment.
[0089] The HMD401 includes lenses 404, 405, 406, 407, 408, and 409, a right-eye image display element 410, a left-eye image display element 411, a right-eye imaging unit 412, a right-eye light source 413, a left-eye imaging unit 414, and a left-eye light source 415. Lenses 404, 405, and 406 constitute the right-eye eyepiece optical system, and lenses 407, 408, and 409 constitute the left-eye eyepiece optical system. The right-eye image display element 410 and the left-eye image display element 411 are, for example, organic EL displays. The right-eye imaging unit 412 and the right-eye light source 413 are located between lenses 404 and 405. The left-eye imaging unit 414 and the left-eye light source 415 are located between lenses 407 and 408. The right eye imaging unit 412 and the left eye imaging unit 414 are infrared cameras, each containing an image sensor.
[0090] The right eyepiece optical system magnifies and projects the original image displayed on the right eye image display element 410 as a virtual image and guides it to the observer's right eye 402. The left eyepiece optical system magnifies and projects the original image displayed on the left eye image display element 411 as a virtual image and guides it to the observer's left eye 403.
[0091] The eyepiece optical system of this embodiment is not an optical system that folds the optical path using polarization.
[0092] The imaging optical system of this embodiment includes a light source that illuminates the observer's eye and an imaging unit that images the observer's eye, and is an optical system that detects the line of sight by photographing the observer's eye. Its optical path will be described below. Figure 23 is an explanatory diagram of the optical path of the imaging optical system of this embodiment.
[0093] The right eye light source 413 is an infrared light source that emits light in a wavelength range (second wavelength range) longer than the visible light wavelength range (first wavelength range). Light from the right eye light source 413 passes through the lens 404, the phase plate 417, and the polarizer (first absorbing polarizer) 416 to illuminate the right eye 402. Light from the right eye 402 passes through the polarizer 416, the phase plate 417, and the lens 404 and enters the right eye imaging unit 412. The right eye imaging unit 412 uses the received light to acquire an image of the right eye 402. By making the optical path of the imaging optical system that detects the observer's line of sight common with the eyepiece optical system in this way, the optical system can be made smaller. Specifically, the visible light from the right eye image display element 410 and the infrared light from the right eye light source 413 share the lens 404, the phase plate 417, and the polarizer 416. Furthermore, the infrared light from the right eye light source 413 does not pass through lenses 405 and 406 and is not shared between them.
[0094] If the observer is wearing glasses 418, the optical path of the observation optical system will be as shown in Figure 24. However, as shown in Figure 25(a), multiple reflections occur between the glasses 418 and the right-eye image display element 410 side of the lens 404, resulting in glasses ghosting that enters the right-eye imaging unit 412.
[0095] In this embodiment, a phase plate 417 with a phase difference of λ / 4 corresponding to the infrared light source and a polarizing plate 416, which is an absorption type polarizing plate corresponding to the infrared light source, are placed between the lens 404 and the right eye 402. As a result, infrared light emitted from the right eye light source 413 passes through the phase plate 417 and the polarizing plate 416, becomes linearly polarized, and is reflected by the glasses 418. The light reflected by the glasses 418 passes through the polarizing plate 416 and the phase plate 417, becomes circularly polarized, and enters the lens 404. This circularly polarized light is reflected from the surface of the lens 404 on the right eye image display element 410 side, passes through the phase plate 417, and becomes linearly polarized. This linearly polarized light is absorbed by the polarizing plate 416 because its polarization direction is rotated by 90° from the previous linearly polarized light. Therefore, as shown in Figure 25(b), the glasses ghost that occurs due to multiple reflections between the glasses 418 and the surface of the lens 404 on the right eye image display element 410 side can be reduced.
[0096] Although the phase plate 417 and polarizer 416 correspond to wavelengths in the infrared region, the light from the right-eye image display element 410 is in the visible light region, and the visible light region may only have transmission characteristics. This makes it possible to prevent glasses ghosting without reducing the efficiency of the light from the right-eye image display element 410.
[0097] In this way, by aligning the polarizing plate 416 with the wavelength in the infrared region from the right eye light source 413, the light from the right eye light source 413 is emitted from the eyepiece optical system in a linearly polarized state, thereby reducing the ghosting effect on eyeglasses.
[0098] Furthermore, since reflected light from the surface of the polarizer 416 is also generated in the optical path of the spectacle ghost shown in Figure 25(a), an anti-reflective coating corresponding to the infrared and visible light regions may be deposited on the surface of the polarizer 416. This can further reduce spectacle ghosting.
[0099] Furthermore, the central wavelength of the right eye light source 413 is 820 nm, and it is desirable that the wavelength of the infrared light used to detect the line of sight be 800 nm or higher.
[0100] Each embodiment disclosed includes the following configuration: (Composition 1) An eyepiece optical system that guides the light emitted from the image display element to the observer's eye, A light source for illuminating the aforementioned eye, It has an imaging unit for imaging the eye, The eyepiece optical system comprises a lens and a first absorbing polarizer disposed between the lens and the eye, which transmits linearly polarized light in a first direction. The imaging unit uses the light transmitted through the lens to image the eye, An image display device characterized in that the light emitted from the light source and guided to the eye is linearly polarized in the first direction. (Configuration 2) The image display device according to configuration 1, characterized in that the first absorbing polarizer changes the light emitted from the light source to linearly polarized light in the first direction. (Composition 3) The image display device according to configuration 1 or 2, characterized in that the eyepiece optical system includes a reflective polarizer that transmits linearly polarized light in the first direction and reflects linearly polarized light in a second direction perpendicular to the first direction. (Composition 4) The image display device according to configuration 3, characterized in that one of the first absorbing polarizer and the reflective polarizer changes the light emitted from the light source to linearly polarized light in the first direction. (Composition 5) The light emitted from the image display element is light in a first wavelength range. The light emitted from the light source is light in a second wavelength range different from the first wavelength range. The image display device according to configuration 4, characterized in that the reflective polarizer has a transmittance of 10% or less for linear polarization in the second direction of the first and second wavelength ranges. (Composition 6) The light emitted from the image display element is light in a first wavelength range. The light emitted from the light source is light in a second wavelength range different from the first wavelength range. The first absorbing polarizer and the reflective polarizer have a transmittance of 10% or less for linearly polarized light in the second direction in the first and second wavelength ranges. The image display device according to configuration 5, characterized in that the other of the first absorbing polarizer and the reflective polarizer has a transmittance of 10% or less for linearly polarized light in the second direction in the first wavelength range, and a transmittance of 70% or more for linearly polarized light in the second direction in the second wavelength range. (Composition 7) The light emitted from the image display element is light in a first wavelength range. The light emitted from the light source is light in a second wavelength range different from the first wavelength range. The eyepiece optical system includes a phase plate positioned between the lens and the eye, The image display device according to any one of configurations 1 to 6, characterized in that the phase plate has an ellipticity of 70% or more for light in the first and second wavelength ranges. (Composition 8) The aforementioned lens has a transmissive reflective surface formed therein. The image display device according to any one of configurations 1 to 7, characterized in that the surface on which the transmission and reflection surface of the lens is formed is convex toward the aspherical image display element. (Composition 9) The light emitted from the image display element is light in a first wavelength range. The image display device according to any one of configurations 1 to 8, characterized in that the light emitted from the light source is light in a second wavelength range different from the first wavelength range. (Composition 10) The image display device according to configuration 9, characterized in that the second wavelength range is a wavelength range with longer wavelengths than the first wavelength range. (Composition 11) The first wavelength range is the wavelength range from 400 nm to 750 nm. The image display device according to configuration 9 or 10, characterized in that the second wavelength range is a wavelength range from 800 nm to 1200 nm. (Composition 12) An image display device according to any one of configurations 1 to 11, characterized in that the light emitted from the light source passes through the lens, through the first absorbing polarizer, is reflected by the eye, passes through the first absorbing polarizer, passes through the lens, and is guided to the imaging unit. (Composition 13) The light emitted from the light source is linearly polarized in the first direction. An image display device according to any one of configurations 1 to 11, characterized in that the light emitted from the light source is reflected by the eye, passes through the first absorbing polarizer, passes through the lens, and is guided to the imaging unit. (Composition 14) The eyepiece optical system includes a phase plate positioned between the lens and the eye, The light emitted from the light source is circularly polarized light that, after passing through the phase plate, becomes linearly polarized in the first direction. An image display device according to any one of configurations 1 to 11, characterized in that the light emitted from the light source passes through the lens, through the phase plate, through the first absorbing polarizer, is reflected by the eye, passes through the first absorbing polarizer, through the phase plate, through the lens, and is guided to the imaging unit. (Composition 15) The eyepiece optical system includes a second absorbing polarizer positioned between the image display element and the lens. An image display device according to any one of configurations 1 to 14, characterized in that the light emitted from the light source, reflected by the eye, and then guided to the imaging unit does not pass through the second absorbing polarizer. (Composition 16) The light emitted from the image display element is light in a first wavelength range. The light emitted from the light source is light in a second wavelength range different from the first wavelength range. The first absorbing polarizer has a transmittance of 10% or less for linearly polarized light in a second direction perpendicular to the first direction in the second wavelength range. The image display device according to configuration 15, characterized in that the second absorbing polarizer has a transmittance of 70% or more for linearly polarized light in the second direction in the second wavelength range. (Composition 17) Optical elements are bonded to the aforementioned lens. The light emitted from the image display element does not pass through the optical element. The image display device according to any one of configurations 1 to 16, characterized in that the imaging unit receives light transmitted through the optical element. (Composition 18) The light emitted from the image display element is light in a first wavelength range. The light emitted from the light source is light in a second wavelength range different from the first wavelength range. The image display device according to configuration 17, characterized in that the optical element is coated with a paint that absorbs light in the second wavelength range.
[0101] 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]
[0102] 101, 201, 301, 401 Head-mounted displays (image display devices) 102,202,302,402 Right eye 103,203,303,403 left eye 104, 105, 106, 107, 204, 205, 206, 207, 304, 305, 306, 307, 404, 405, 406, 407, 408, 409 lenses 108,208,308,410 Image display elements for the right eye 109,209,309,411 Left eye image display element 115,215,315,416 Polarizing plates (first type of absorbing polarizer) 116,216,316,412 Imaging unit for right eye 118,218,318,414 Left eye imaging unit 117, 217, 317, 413 Right eye using light source 119, 219, 319, 415 Left eye light source
Claims
1. An eyepiece optical system that guides the light emitted from the image display element to the observer's eye, A light source for illuminating the aforementioned eye, It has an imaging unit for imaging the eye, The eyepiece optical system comprises a lens and a first absorbing polarizer disposed between the lens and the eye, which transmits linearly polarized light in a first direction. The imaging unit uses the light transmitted through the lens to image the eye, An image display device characterized in that the light emitted from the light source and guided to the eye is linearly polarized in the first direction.
2. The image display device according to claim 1, characterized in that the first absorbing polarizer changes the light emitted from the light source to linearly polarized light in the first direction.
3. The light emitted from the image display element is light in the first wavelength range. The light emitted from the light source is light in a second wavelength range different from the first wavelength range. The image display device according to claim 2, characterized in that the first absorbing polarizer has a transmittance of 10% or less for linearly polarized light in a second direction perpendicular to the first direction in the first and second wavelength ranges.
4. The image display device according to claim 1, characterized in that the eyepiece optical system includes a reflective polarizer that transmits linearly polarized light in the first direction and reflects linearly polarized light in a second direction perpendicular to the first direction.
5. The image display device according to claim 4, characterized in that one of the first absorbing polarizer and the reflective polarizer changes the light emitted from the light source to linearly polarized light in the first direction.
6. The light emitted from the image display element is light in the first wavelength range. The light emitted from the light source is light in a second wavelength range different from the first wavelength range. One of the first absorbing polarizer and the reflective polarizer has a transmittance of 10% or less for linearly polarized light in the second direction in the first and second wavelength ranges. The image display device according to claim 5, characterized in that the other of the first absorbing polarizer and the reflective polarizer has a transmittance of 10% or less for linearly polarized light in the second direction in the first wavelength range, and a transmittance of 70% or more for linearly polarized light in the second direction in the second wavelength range.
7. The light emitted from the image display element is light in the first wavelength range. The light emitted from the light source is light in a second wavelength range different from the first wavelength range. The eyepiece optical system includes a phase plate positioned between the lens and the eye, The image display device according to any one of configurations 1 to 6, characterized in that the phase plate has an ellipticity of 70% or more with respect to light in the first and second wavelength ranges.
8. The aforementioned lens has a transmissive reflective surface formed therein. The image display device according to any one of configurations 1 to 6, characterized in that the surface on which the transmission and reflection surface of the lens is formed is convex toward the aspherical image display element.
9. The light emitted from the image display element is light in the first wavelength range. The image display device according to any one of configurations 1 to 6, characterized in that the light emitted from the light source is light in a second wavelength range different from the first wavelength range.
10. The image display device according to claim 9, characterized in that the second wavelength range is a wavelength range with longer wavelengths than the first wavelength range.
11. The first wavelength range is the wavelength range from 400 nm to 750 nm. The image display device according to claim 9, characterized in that the second wavelength range is a wavelength range from 800 nm to 1200 nm.
12. The image display device according to any one of configurations 1 to 6, characterized in that the light emitted from the light source passes through the lens, passes through the first absorbing polarizer, is reflected by the eye, passes through the first absorbing polarizer, passes through the lens, and is guided to the imaging unit.
13. The light emitted from the light source is linearly polarized in the first direction, The image display device according to any one of configurations 1 to 6, characterized in that the light emitted from the light source is reflected by the eye, passes through the first absorbing polarizer, passes through the lens, and is guided to the imaging unit.
14. The eyepiece optical system includes a phase plate positioned between the lens and the eye, The light emitted from the light source is circularly polarized light that, after passing through the phase plate, becomes linearly polarized in the first direction. The image display device according to any one of claims 1 to 6, characterized in that the light emitted from the light source passes through the lens, through the phase plate, through the first absorbing polarizer, is reflected by the eye, passes through the first absorbing polarizer, through the phase plate, through the lens, and is guided to the imaging unit.
15. The eyepiece optical system includes a second absorbing polarizer disposed between the image display element and the lens, The image display device according to any one of claims 1 to 6, characterized in that the light emitted from the light source, reflected by the eye, and then guided to the imaging unit does not pass through the second absorbing polarizer.
16. The light emitted from the image display element is light in the first wavelength range. The light emitted from the light source is light in a second wavelength range different from the first wavelength range. The first absorbing polarizer has a transmittance of 10% or less for linearly polarized light in a second direction perpendicular to the first direction in the second wavelength range. The image display device according to claim 15, characterized in that the second absorbing polarizer has a transmittance of 70% or more for linearly polarized light in the second direction in the second wavelength range.
17. Optical elements are bonded to the aforementioned lens. The light emitted from the image display element does not pass through the optical element. The image display device according to any one of claims 1 to 6, characterized in that the imaging unit receives light transmitted through the optical element.
18. The light emitted from the image display element is light in the first wavelength range. The light emitted from the light source is light in a second wavelength range different from the first wavelength range. The image display device according to claim 17, characterized in that the optical element is coated with a paint that absorbs light in the second wavelength range.