Image display device

Abstract

To provide a thin type image display device while having an imaging function for detecting a visual line.SOLUTION: An image display device comprises: a display element that displays an image; and an optical system that guides light from the display element to an observer. The display element comprises a light receiving unit that performs photo-electric conversion of light from eyes of the observer. The optical system comprises first to third reflection transmission surfaces that are sequentially arranged from a side of the display element to a side of the observer. In the image display device, a display optical path in which sequentially from the side of the display element, light from the display element is transmitted through the first to second reflection transmission surfaces, is reflected by the third to second reflection transmission surfaces, is transmitted through the third reflection transmission surface, and is guided to eyes of the observer, and an image optical path, in which sequentially from the side of the observer, light from the eyes is transmitted through the third to second reflection transmission surfaces, is reflected by the first reflection transmission surface, is transmitted through the second reflection transmission surface, is reflected by the third reflection transmission surface, is transmitted through the second to first reflection transmission surfaces, and is guided to the display element are formed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image display device suitable for a head mounted display or the like with a gaze detection function. [Background technology]

[0002] Conventionally, a head mounted display (HMD) incorporating an imaging device for detecting the line of sight has been proposed. Non-Patent Document 1 discloses a display device having an imaging function for detecting the line of sight, using a display element having a light receiving part in the display area. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Dr.Rigo Herold, OLED based binocular interactive see-through HMD,5.6.2012,SID2012 Exhibitors' Forum Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Non-Patent Document 1, the concave mirror for imaging and the concave mirror for display are arranged in directions offset by 90° so that the optical paths for imaging and the optical paths for display are branched and integrated by a 45° semi-transmissive reflective surface. With this arrangement, the concave mirror for imaging and the concave mirror for display need to have approximately the same diameter, making it difficult to make the device thinner.

[0005] An object of the present invention is to provide a thin image display device having an imaging function for detecting a line of sight. [Means for solving the problem]

[0006] An image display device according to one aspect of the present invention includes a display element having a display area for displaying an image, and an optical system for guiding light from the display element to an observer, the display element having a light receiving section within the display area for photoelectrically converting light from the observer's eye, the optical system having a first reflective / transmissive surface, a second reflective / transmissive surface, and a third reflective / transmissive surface arranged in this order from the display element side to the observer side, and the light from the display element passes through the first reflective / transmissive surface and the second reflective / transmissive surface in this order from the display element side. a display optical path in which light from the eye is transmitted through the first reflective-transmissive surface, reflected by the third reflective-transmissive surface, reflected by the second reflective-transmissive surface, transmitted through the third reflective-transmissive surface, and guided to the eye of the observer; and an imaging optical path in which light from the eye is transmitted through the third reflective-transmissive surface, transmitted through the second reflective-transmissive surface, reflected by the first reflective-transmissive surface, transmitted through the second reflective-transmissive surface, reflected by the third reflective-transmissive surface, transmitted through the second reflective-transmissive surface, transmitted through the first reflective-transmissive surface, and guided to the display element, in that order from the observer's side. Effect of the Invention

[0007] According to the present invention, it is possible to provide a thin image display device having an imaging function for detecting a line of sight. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram illustrating a main part of an image display device according to a first embodiment. [Diagram 2] 1 is a diagram showing a display element according to a first embodiment as viewed from the front. [Diagram 3] 1 is a diagram for explaining the spectral characteristics of an infrared semi-transmissive reflective surface and a visible semi-transmissive reflective surface. [Figure 4] FIG. 2 is a diagram for explaining a display light path and an imaging light path in the first embodiment. [Diagram 5] FIG. 2 is a diagram showing a specific example of a display light path in the first embodiment. [Figure 6] FIG. 2 is a diagram illustrating a specific example of an imaging optical path according to the first embodiment. [Figure 7] FIG. 11 is a schematic diagram illustrating a main part of an image display device according to a second embodiment. [Figure 8] FIG. 11 is a front view of a display element according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to refer to the same components, and duplicated descriptions will be omitted. [First embodiment] 1 is a schematic diagram of a main part of an image display device 1 according to the present embodiment. The image display device 1 has an optical system 10, a display element 20, and an illumination system 30. The elements of the optical system 10 are coaxially configured with an optical axis 100 as a common axis. The display element 20 is, for example, an OLED, and has a display area 21 including a plurality of pixels. The illumination system 30 is, for example, an infrared LED, and emits infrared light. S is an exit pupil when the optical system 10 is used as a display optical system that guides light from the display element 20 to an observer (user), and is a suitable location for placing the observer's pupil.

[0010] The optical system 10 includes a lens unit 110. The lens unit 110 is a cemented lens in which a plano-concave lens 111, a meniscus lens 112, and a plano-convex lens 113 are cemented together, and serves to form an image. The plano-concave lens 111 and the meniscus lens 112 are cemented together with an infrared semi-transmissive reflective film formed on one surface thereof to serve as an infrared semi-transmissive reflective portion. The cemented surface of the plano-concave lens 111 and the meniscus lens 112 acts as an infrared semi-transmissive reflective surface (first reflecting / transmitting surface) 11. The meniscus lens 112 and the plano-convex lens 113 are cemented together with a visible semi-transmissive reflective film formed on one surface thereof to serve as a visible semi-transmissive reflective portion. The cemented surface of the meniscus lens 112 and the plano-convex lens 113 acts as a visible semi-transmissive reflective surface 12 (second reflecting / transmitting surface) 12.

[0011] On the display element 20 side (panel side) of the lens unit 110, the linear polarizer 120 and the first λ / 4 phase shifter 130 are bonded together to form an integrated element. On the exit pupil S side of the optical system 10 of the lens unit 110, the second λ / 4 phase shifter 140 and the polarizing beam splitter 150 are bonded together to form an integrated element. The joint surface between the second λ / 4 phase shifter 140 and the polarizing beam splitter 150 acts as a polarizing beam splitter surface (third reflective / transmissive surface) 13.

[0012] 2 is a front view of a display element 20 according to this embodiment. The display element 20 includes a plurality of light receiving sections 22 arranged discretely within a display area 21, and functions as an imaging element in which the plurality of light receiving sections 22 serve as pixels. The light receiving sections 22 are sensitive to light in the infrared range (infrared light), and photoelectrically convert light from the observer's eye.

[0013] Figures 3(A) and 3(B) are diagrams for explaining the spectral characteristics of the infrared semi-transmissive reflective surface 11 and the visible semi-transmissive reflective surface 12, respectively. In Figures 3(A) and 3(B), the horizontal axis is wavelength, and the vertical axis is transmittance or reflectance. The vertical dashed line indicates the boundary between the visible range and the infrared range, with the visible range to the left and the infrared range to the right of the boundary. In the graphs, the solid line represents transmittance, and the dashed line represents reflectance.

[0014] 3(A), the infrared semi-transmissive reflective surface 11 acts as a nearly transmissive surface for visible light. Near the boundary between the visible and infrared regions, the reflectance increases and the transmittance decreases, but in the infrared region, the two are close to each other, and the infrared semi-transmissive reflective surface 11 acts as a semi-transmissive reflective surface.

[0015] 3(B), the reflectance and transmittance have certain values ​​in the visible range, and the visible semi-transmissive reflective surface 12 acts as a semi-transmissive reflective surface. Near the boundary between the visible range and the infrared range, the transmittance increases and the reflectance decreases, and the visible semi-transmissive reflective surface 12 acts as a nearly transparent surface for infrared light.

[0016] The wavelength at the boundary between the visible range and the infrared range is set to at least 700 nm or more. If it is less than that, it is undesirable because the infrared light used for imaging is likely to be visible to many observers. It is preferable to set the wavelength at the boundary between the visible range and the infrared range to 830 nm. In this case, there will be almost no observers who can see the infrared light.

[0017] Furthermore, the above-mentioned conditions are ideal, and in reality, reflection of about 15% on the transmission side is acceptable, and even if the reflectance does not equal the transmittance on the semi-transmission / reflection side, it is sufficient if the reflectance × transmittance is about 20%.

[0018] 4 is a diagram for explaining the display optical path and the image pickup optical path in this embodiment. Since the purpose of FIG. 4 is to explain how both optical paths are formed by polarized light, each element is simplified and represented by a straight line.

[0019] The linear polarizer 120 and the polarizing beam splitter 150 (polarizing beam splitting surface 13) are indicated with their respective transmission polarization axes. That is, the linear polarizer 120 has the property of transmitting polarized light (called first linearly polarized light) whose electric field vibration plane is the paper surface, and absorbing polarized light (called second linearly polarized light) whose electric field vibration plane is perpendicular to the paper surface. The polarizing beam splitter 150 has the property of transmitting the second linearly polarized light and reflecting the first linearly polarized light. The first λ / 4 phase shifter 130 and the second λ / 4 phase shifter 140 are indicated with their respective slow axis directions as viewed from the exit pupil S side toward the display element 20 side.

[0020] First, the display optical path shown in the upper part of FIG. 4 will be described. The visible light emitted from the display region 21 passes through the linear polarizer 120 to become the first linearly polarized light, passes through the first λ / 4 phase shifter 130 to become right-handed circularly polarized light, and heads toward the infrared semi-transmissive reflecting surface 11. The infrared semi-transmissive reflecting surface 11 transmits almost all of the visible light, so the light passes as right-handed circularly polarized light and enters the visible semi-transmissive reflecting surface 12. The visible semi-transmissive reflecting surface 12 reflects a portion of the light, but the rest passes as right-handed circularly polarized light, passes through the second λ / 4 phase shifter 140 to become the first linearly polarized light, and enters the polarizing beam splitter surface 13. The polarizing beam splitter surface 13 reflects the light as the first linearly polarized light, enters the second λ / 4 phase shifter 140 to become right-handed circularly polarized light, and enters the visible semi-transmissive reflecting surface 12. A portion of the light is transmitted by the visible semi-transmissive reflective surface 12, but the remainder is reflected to become left-handed circularly polarized light, which enters the second λ / 4 phase shifter 140 and becomes second linearly polarized light, and then passes through the polarizing beam splitter surface 13 toward the exit pupil S. The above optical path is the display optical path in this embodiment. An observer whose eyes are positioned near the exit pupil S will see an enlarged virtual image of the original image formed in the display area 21, mainly due to the imaging effect caused by reflection at the visible semi-transmissive reflective surface 12.

[0021] Next, the imaging optical path at the bottom of FIG. 4 will be described. As a prerequisite for entering the imaging optical path, the observer's eye (not shown) located near the exit pupil S in the display optical path is illuminated with infrared light from the illumination system 30. Of the light that receives and is scattered / reflected by the infrared light, only the second linearly polarized light passes through the polarizing beam splitter surface 13, and the light enters and passes through the second λ / 4 phase shifter 140 to become left-handed circularly polarized light, and enters the visible semi-transmissive reflecting surface 12. Since the visible semi-transmissive reflecting surface 12 transmits almost all of the infrared light, the light remains left-handed circularly polarized light and enters the infrared semi-transmissive reflecting surface 11. The light reflected by the infrared semi-transmissive reflecting surface 11 becomes right-handed circularly polarized light, passes through the visible semi-transmissive reflecting surface 12 as right-handed circularly polarized light, enters the second λ / 4 phase shifter 140, becomes the first linearly polarized light, is reflected by the polarizing beam splitter surface 13, and enters the second λ / 4 phase shifter 140. On the other hand, a part of the light that reaches the infrared semi-transmissive reflective surface 11 is transmitted and becomes the second linearly polarized light by the first λ / 4 phase shifter 130, enters the linear polarizer 120, and is absorbed by the linear polarizer 120. The infrared light that passes through the second λ / 4 phase shifter 140 and becomes the right-handed circularly polarized light passes through the visible semi-transmissive reflective surface 12 and enters the infrared semi-transmissive reflective surface 11. The right-handed circularly polarized light that passes through the infrared semi-transmissive reflective surface 11 passes through the first λ / 4 phase shifter 130 and becomes the first linearly polarized light, passes through the linear polarizer 120, and enters the display area 21. The above optical path is the imaging optical path in this embodiment. An image of the eye is formed in the display area 21 by the imaging action that occurs mainly when the infrared light passes through the imaging optical path with the observer's eye as the object light and is reflected by the infrared semi-transmissive reflective surface 11. The light and dark of the image are photoelectrically converted by the corresponding light receiving section 22 to form image information of the eye, and by appropriately processing the image information, information on the line of sight of the observer's eye can be obtained. Furthermore, according to the present invention, an image viewed from the front direction of the observer's eye can be obtained.

[0022] As described above, the image display device 1 of the present embodiment includes a display element 20 having a light receiving unit 22 in a display area 21, a thin coaxial optical system, and includes a display optical path and an imaging optical path formed by three reflective / transmissive surfaces. In the display optical path, the display light emitted from the display element 20 passes through the first reflective / transmissive surface, passes through the second reflective / transmissive surface, is reflected by the third reflective / transmissive surface, is reflected by the second reflective / transmissive surface, is transmitted through the third reflective / transmissive surface, and is guided to the exit pupil S. In the imaging optical path, the object light passes through the third reflective / transmissive surface, passes through the second reflective / transmissive surface, is reflected by the first reflective / transmissive surface, is transmitted through the second reflective / transmissive surface, is reflected by the third reflective / transmissive surface, is transmitted through the second reflective / transmissive surface, is transmitted through the first reflective / transmissive surface, and is guided to the display element 20. With this configuration, an enlarged virtual image of the image on the display element 20 is presented to the observer's eye, and the observer's line of sight information can be acquired by forming an image of the observer's eye on the display element 20. In particular, by reducing the distance between the first reflective / transmissive surface and the second reflective / transmissive surface, the thickness of the optical system 10 can be made thinner than the diameter of the optical system 10, and therefore the image display device 1 can be made thinner.

[0023] Figures 5 and 6 are diagrams showing specific examples of the display light path and the image pickup light path in this embodiment, respectively. In the configurations of Figures 5 and 6, the surface of the lens unit 110 closest to the display element 20 is configured as a curved surface, and therefore the linear polarizer 120 and the first λ / 4 phase shifter 130 are configured as separate bodies from the lens unit 110, which is different from the configuration of Figure 1. The other configurations are the same as those of Figure 1, and therefore explanations of the symbols, light paths, functions, etc. will be omitted.

[0024] 5, the configuration is such that the chief ray obtained by back ray tracing from the exit pupil S heads in a direction that converges on the display element 20. This makes it possible to provide an image display device 1 that is capable of displaying at a wide angle of view compared to the size of the display area 21 of the display element 20.

[0025] 6, the entrance pupil in the imaging optical path is located closest to the exit pupil S of the optical system 10, and the chief ray is incident in a direction that diverges toward the display area 21, that is, the exit pupil in the imaging optical path is located on the optical system 10 side rather than the display element 20. This makes it possible to prevent the chief ray from being focused near the infrared semi-transmissive reflective surface 11 when reflected by the infrared semi-transmissive reflective surface 11, which bears the main power for imaging, and suppress the occurrence of field curvature.

[0026] In addition, when the refractive power (power) of the first reflective-transmissive surface during reflection is φ1 and the refractive power (power) of the second reflective-transmissive surface during reflection is φ2, and the first reflective-transmissive surface and the second reflective-transmissive surface are used in the same position, it is necessary to satisfy the relationship φ1 ≈ 2 × φ2. In this embodiment, it is preferable to satisfy the following conditional formula (1) in order to make it possible to arrange the first reflective-transmissive surface closer to the display element 20 than the second reflective-transmissive surface and to make the overlapping optical path length of the imaging optical path longer than the display optical path.

[0027] 1<φ1 / φ2<2 (1) By satisfying the above conditional expression, the power at the first reflective-transmissive surface is reduced, the occurrence of aberration is suppressed, and an image of the observer's eye located near the exit pupil S can be formed on the display element 20 even with a simple configuration to obtain an image of the eye. If the upper limit is exceeded, it becomes difficult to suppress the occurrence of aberration at the first reflective-transmissive surface. If the lower limit is not satisfied, the distance between the first reflective-transmissive surface and the second reflective-transmissive surface must be increased, which increases the thickness of the optical system 10.

[0028] It is more preferable that the numerical range of conditional expression (1) be the numerical range of the following conditional expression (1a).

[0029] 1.1<φ1 / φ2<1.9 (1a) It is further preferable that the numerical range of conditional formula (1) be the numerical range of the following conditional formula (1b).

[0030] 1.2<φ1 / φ2<1.8 (1b) In addition, the light receiving section 22 of the display element 20 has sensitivity in the infrared region, the first reflective / transmissive surface has a semi-transmissive reflecting effect in the infrared region and a transmitting property in the visible region, and the second reflective / transmissive surface has a semi-transmissive reflecting effect in the visible region and a transmitting property in the infrared region, thereby enabling imaging and display with little loss of infrared light used for imaging and visible light used for display. [Second embodiment] Fig. 7 is a schematic diagram of a main part of an image display device 1 of this embodiment. Fig. 8 is a front view of a display element 20 of this embodiment.

[0031] In this embodiment, the light emitting unit 23, which acts similarly to the illumination system 30, is disposed around the display area 21 of the display element 20. In addition, in this embodiment, the infrared semi-transmissive reflective film forming unit 11E, which is an area through which light passes in the display optical path and the imaging optical path of the infrared semi-transmissive reflective surface 11, is restricted to a range in which the light ray from the light emitting unit 23 toward the center of the exit pupil S in the display optical path of the optical system 10 does not overlap. Furthermore, in this embodiment, the diameters of the linear polarizer 120 and the first λ / 4 phase shifter 130 are restricted to a range in which the light ray from the light emitting unit 23 toward the center of the exit pupil S in the display optical path of the optical system 10 does not overlap. The other configurations are the same as those in the first embodiment, so detailed description will be omitted. The light emitting unit 23 may be disposed within the display area 21.

[0032] The illumination, imaging, and display functions of this embodiment will be described below.

[0033] The infrared light emitted from the light emitting unit 23 does not pass through the linear polarizer 120 and the first λ / 4 phase shifter 130, but enters the lens unit 110. The light that enters the lens unit 110 passes through the infrared semi-transmissive reflecting surface 11 outside the infrared semi-transmissive reflective film forming unit 11E, and is basically only transmitted and guided to the visible semi-transmissive reflecting surface 12. Since the visible semi-transmissive reflecting surface 12 also has a characteristic of almost transmitting infrared light, the light emitted from the lens unit 110 in a state of little loss passes through the second λ / 4 phase shifter 140 with almost no loss, and the second linearly polarized component passes through the polarizing beam splitter surface 13 and is guided to the exit pupil S. Therefore, the infrared light emitted from the light emitting unit 23 reaches the exit pupil S without much loss except at the polarizing beam splitter surface 13 where a loss of about 50% occurs, and illuminates the eye (not shown) of the observer whose pupil is located near the exit pupil S.

[0034] The infrared light scattered / reflected by the eye passes through the third reflective / transmissive surface, passes through the second reflective / transmissive surface, is reflected by the first reflective / transmissive surface, passes through the second reflective / transmissive surface, is reflected by the third reflective / transmissive surface, passes through the second reflective / transmissive surface, passes through the first reflective / transmissive surface, and is guided to the display element 20. Image information of the eye is acquired by such an imaging optical path.

[0035] Moreover, the display light in the visible range emitted from the display element 20 passes through the first reflective / transmissive surface, passes through the second reflective / transmissive surface, is reflected by the third reflective / transmissive surface, is reflected by the second reflective / transmissive surface, passes through the third reflective / transmissive surface, and is guided to the exit pupil S. By such a display optical path, a magnified virtual image is presented to the eye of the observer located near the exit pupil S.

[0036] With the above configuration, an enlarged virtual image of the image on the display element 20 is presented to the observer's eye, and the observer's line of sight information can be acquired by forming an image of the observer's eye on the display element 20. In particular, by reducing the distance between the first reflective / transmissive surface and the second reflective / transmissive surface, the thickness of the optical system 10 can be made thinner than the diameter of the optical system 10, and therefore the image display device 1 can be made thinner.

[0037] In this embodiment, by providing the light emitting unit 23 instead of the illumination system 30, the space required for arranging the illumination system 30 can be reduced, and therefore the image display device 1 can be made even smaller than in the first embodiment. Also, in this embodiment, the infrared semi-transmissive reflective film forming unit 11E is restricted to a range in which the light ray from the light emitting unit 23 to the center of the exit pupil S does not overlap, and the diameters of the linear polarizer 120 and the first λ / 4 phase shifter 130 are restricted to a range in which the light ray from the light emitting unit 23 to the center of the exit pupil S does not overlap. This makes it possible to realize an illumination system with little loss.

[0038] In Figures 1 and 5, only the chief ray and marginal ray at the central angle of view are shown, but in accordance with the present invention, the exit pupil S in the imaging optical path is positioned closer to the optical system 10 than the display element 20, and the entrance pupil S in the display optical path is positioned farther away than the display element 20. This makes it possible to achieve both wide-angle display and high-performance imaging.

[0039] The disclosure of this embodiment includes the following configuration. (Configuration 1) a display element having a display area for displaying an image; an optical system for directing light from the display element to an observer; the display element includes a light receiving section that photoelectrically converts light from the viewer's eye within the display area, the optical system includes a first reflective-transmissive surface, a second reflective-transmissive surface, and a third reflective-transmissive surface, which are arranged in this order from the display element side to the viewer side, a display optical path along which light from the display element passes through the first reflective / transmissive surface, passes through the second reflective / transmissive surface, is reflected by the third reflective / transmissive surface, is reflected by the second reflective / transmissive surface, passes through the third reflective / transmissive surface, and is guided to an eye of the observer, in this order from the display element side; an imaging optical path is formed in which light from the eye passes through the third reflective / transmissive surface, passes through the second reflective / transmissive surface, is reflected by the first reflective / transmissive surface, passes through the second reflective / transmissive surface, is reflected by the third reflective / transmissive surface, passes through the second reflective / transmissive surface, passes through the first reflective / transmissive surface, and is guided to the display element, in that order from the observer's side. (Configuration 2) the light receiving unit is sensitive to infrared light, the first reflective / transmissive surface has a characteristic of acting as a semi-transmissive reflective surface for infrared light and transmitting visible light; 2. The image display device according to configuration 1, wherein the second reflective / transmissive surface acts as a semi-transmissive reflective surface for visible light and has a property of transmitting infrared light. (Configuration 3) the display element includes a light emitting portion that emits infrared light, 3. The image display device according to claim 1, wherein the infrared light from the light-emitting unit is guided to the eye without passing through a region of the first reflective / transmissive surface through which light in the display optical path and light in the imaging optical path pass. (Configuration 4) An image display device according to any one of configurations 1 to 3, characterized in that an exit pupil in the imaging optical path is located closer to the optical system than the display element, and an entrance pupil in the display optical path is located farther away than the display element. (Configuration 5) When the refractive power of the first reflective-transmissive surface at the time of reflection is φ1 and the refractive power of the second reflective-transmissive surface at the time of reflection is φ2, 1<φ1 / φ2<2 5. The image display device according to any one of configurations 1 to 4, wherein the following conditional expression is satisfied: (Configuration 6) 6. The image display device according to any one of configurations 1 to 5, wherein the first reflective-transmissive surface, the second reflective-transmissive surface, and the third reflective-transmissive surface are arranged coaxially.

[0040] Although the 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 the gist of the present invention. [Explanation of symbols]

[0041] 1 Image display device 10 Optical system 11 Infrared semi-transmissive reflective surface (first reflective / transmissive surface) 12 Visible semi-transparent reflective surface (second reflective / transmissive surface) 13 Polarizing beam splitter surface (third reflecting / transmitting surface) 20 Display element 21 Display area 22 Light receiving part

Claims

1. a display element having a display area for displaying an image; an optical system for directing light from the display element to an observer; the display element includes a light receiving section that photoelectrically converts light from the viewer's eye within the display area, the optical system includes a first reflective-transmissive surface, a second reflective-transmissive surface, and a third reflective-transmissive surface, which are arranged in this order from a side of the display element to a side of the observer, a display optical path along which light from the display element passes through the first reflective / transmissive surface, passes through the second reflective / transmissive surface, is reflected by the third reflective / transmissive surface, is reflected by the second reflective / transmissive surface, passes through the third reflective / transmissive surface, and is guided to an eye of the observer, in this order from the display element side; an imaging optical path is formed in which light from the eye passes through the third reflective / transmissive surface, passes through the second reflective / transmissive surface, is reflected by the first reflective / transmissive surface, passes through the second reflective / transmissive surface, is reflected by the third reflective / transmissive surface, passes through the second reflective / transmissive surface, passes through the first reflective / transmissive surface, and is guided to the display element, in that order from the observer's side.

2. the light receiving unit is sensitive to infrared light, the first reflective / transmissive surface has a characteristic of acting as a semi-transmissive reflective surface for infrared light and transmitting visible light; 2. The image display device according to claim 1, wherein the second reflective / transmissive surface has a characteristic of acting as a semi-transmissive reflective surface for visible light and transmitting infrared light.

3. the display element includes a light emitting portion that emits infrared light, 3. The image display device according to claim 1, wherein the infrared light from the light-emitting unit is guided to the eye without passing through a region of the first reflective / transmissive surface through which light in the display optical path and light in the imaging optical path pass.

4. 3. The image display device according to claim 1, wherein an exit pupil in the imaging optical path is located closer to the optical system than the display element, and an entrance pupil in the display optical path is located farther away than the display element.

5. When the refractive power of the first reflective-transmissive surface at the time of reflection is φ1 and the refractive power of the second reflective-transmissive surface at the time of reflection is φ2, 1<φ1 / φ2<2 3. The image display device according to claim 1, wherein the following condition is satisfied:

6. 3. The image display device according to claim 1, wherein the first reflective-transmissive surface, the second reflective-transmissive surface, and the third reflective-transmissive surface are arranged coaxially.

Images