JP7192396B2 - Display device - Google Patents

Description

The present invention relates to a display device that displays images using diffraction elements.

2. Description of the Related Art As a display device using a diffraction element such as a holographic element, there has been proposed one in which image light emitted from an image light generation device is deflected toward an observer's eye by the diffraction element. In the diffraction element, the interference fringes are optimized so that the optimum diffraction angle and diffraction efficiency can be obtained at a specific wavelength. However, since image light has a predetermined spectral width centered on a specific wavelength, light with peripheral wavelengths that deviate from the specific wavelength causes a reduction in image resolution. Therefore, the image light emitted from the image light generation device is emitted toward the second diffraction element arranged in front by the reflective first diffraction element, and the image light emitted from the first diffraction element is emitted to the second diffraction element. Display devices have been proposed in which a diffractive element deflects the light toward the viewer's eye. According to such a configuration, wavelength compensation can be performed by the first diffraction element, and reduction in image resolution caused by light of peripheral wavelengths that deviate from the specific wavelength can be suppressed (see Patent Document 1). A display device has also been proposed that includes two diffractive elements that are designed to mutually compensate for the spread error (see Patent Document 2). Also, in an eyepiece optical system, a technique has been proposed in which two diffraction elements are used to suppress the occurrence of aberration and color shift (see Patent Document 3).

JP 2017-167181 A Japanese Patent Application Laid-Open No. 2004-318140 JP-A-08-184779

However, with the techniques disclosed in Patent Documents 1, 2, and 3, there is a possibility that the two diffraction elements cannot sufficiently compensate for the wavelength, so further improvements have been desired.

In view of the above problems, an object of the present invention is to provide a display device capable of appropriately performing wavelength compensation using two diffraction elements.

In order to solve the above problems, a display device according to a first aspect of the present invention includes a first optical section having positive power and a first diffraction light along an optical path of image light emitted from an image light generation device. a second optical section having a positive power, a third optical section having a positive power, and a fourth optical section having a second diffraction element and having a positive power ; In the optical path, the first optical section is provided between the image light generating device and a first intermediate image of the image light, and in the optical path, the second optical section is provided between the first optical section and a pupil. in the optical path, the third optical section is provided between the second optical section and a second intermediate image of the image light; and in the optical path, the fourth optical section is provided in the It is characterized by being provided between the third optical unit and the exit pupil .

According to the display device according to the first aspect, the first intermediate image of the image light is formed between the first optical section and the third optical section, and the second intermediate image is formed between the third optical section and the fourth optical section. An intermediate image is formed and a pupil is formed in the vicinity of the third optical section. Therefore, the light rays emitted from one point of the image light generating device can be imaged as one point on the retina, and the entrance pupil of the optical system and the pupil of the eyeball can be conjugated, and further, The two diffractive elements (the first diffractive element and the second diffractive element) can be conjugate or nearly conjugate. Therefore, the first diffraction element and the second diffraction element correspond to the incident positions of the same light beam, so that wavelength compensation can be properly performed by the two diffraction elements.

In the display device according to the first aspect, it is possible to employ an aspect in which the first intermediate image is formed between the first optical section and the second optical section. According to this aspect, more sufficient wavelength compensation can be performed than when the first intermediate image is formed between the second optical section and the third optical section.

In the display device according to the first aspect, the third optical section freely controls the image light emitted from the second optical section as divergent light, convergent light, or parallel light, and makes the image light incident on the fourth optical section. Aspects can be employed.

In the display device according to the first aspect, the third optical section deflects the light corresponding to one point of the image generated by the image light generating device by the first diffraction element and deviates from the light of the specific wavelength. It is also possible to employ a mode in which the light is incident on a predetermined range of the second diffraction element. In the present invention, "the light corresponding to one point of the image generated by the image light generating device" means, when the image light generating device is a panel-shaped image light generating device, one of the display surfaces of the panel-shaped image light generating device. It corresponds to light emitted from a point. On the other hand, when the image light generating device generates an image by two-dimensionally scanning laser light with a micromirror device, it corresponds to light emitted in one direction from the micromirror device.

In the display device according to the first aspect, it is possible to employ an aspect in which the second optical section causes the image light emitted from the first optical section to enter the third optical section as convergent light.

In the display device according to the first aspect, the incident surface of the second diffraction element is a concave curved surface in which the central portion is recessed with respect to the peripheral portion, and the second diffraction element emits light from the third optical section. A mode in which the image light is collimated can be adopted.

In the display device according to the first aspect, the absolute value of the magnification of the projection of the first diffraction element onto the second diffraction element by the third optical section is from 0.5 times to 10 times. can be done. In this case, the absolute value of the magnification is preferably from 1 to 5 times.

In the display device according to the first aspect, the optical distance between the first diffraction element and the third optical section is shorter than the optical distance between the third optical section and the second diffraction element. can be done.

In the display device according to the first aspect, it is possible to employ an aspect in which the first diffraction element and the second diffraction element are in a conjugate relationship. Further, the light emitted from the first position in the first diffraction element is incident within a range of ±0.8 mm with respect to the second position corresponding to the first position in the second diffraction element. can be adopted.

A display device according to a second aspect of the present invention has a positive power along an optical path of image light emitted from an image light generation device, and includes a first optical section including a plurality of lenses, and a first diffraction element. comprising a second optical section having positive power, a third optical section having positive power, and a fourth optical section having positive power and comprising a second diffraction element, wherein in the optical path a first intermediate image of the image light is formed between the third optical section and a first lens located closest to the image light generating device among the plurality of lenses in the first optical section; a pupil is formed between the second optical section and the fourth optical section; a second intermediate image of the image light is formed between the third optical section and the fourth optical section; An exit pupil is formed on the side opposite to the third optical unit.

According to the display device according to the second aspect, the first intermediate image of the image light is formed between the first lens and the third optical section, and the second intermediate image is formed between the third optical section and the fourth optical section. An image is formed and a pupil is formed in the vicinity of the third optical section. Therefore, the light rays emitted from one point of the image light generating device can be imaged as one point on the retina, and the entrance pupil of the optical system and the pupil of the eyeball can be conjugated. The two diffractive elements (the first diffractive element and the second diffractive element) can be conjugate or nearly conjugate. Therefore, the first diffraction element and the second diffraction element correspond to the incident positions of the same light beam, so that wavelength compensation can be properly performed by the two diffraction elements.

In the display device according to the second aspect, it is possible to employ an aspect in which the first intermediate image is formed in the first optical section.

1 is an external view showing one aspect of the external appearance of a display device according to a first embodiment; FIG. FIG. 10 is an external view showing another aspect of the external appearance of the display device; 1A and 1B are explanatory views showing one mode of an optical system of a display device; FIG. FIG. 4 is an explanatory diagram of interference fringes of a diffraction element; FIG. 4 is an explanatory diagram of another form of interference fringes of a diffraction element; FIG. 4 is an explanatory diagram showing diffraction characteristics of a first diffraction element and a second diffraction element; FIG. 4 is an explanatory diagram when the first diffraction element and the second diffraction element are in a conjugate relationship; FIG. 4 is an explanatory diagram when the first diffraction element and the second diffraction element are not in a conjugate relationship; FIG. 4 is an explanatory diagram when the first diffraction element and the second diffraction element are not in a conjugate relationship; FIG. 5 is an explanatory diagram showing tolerances for deviations from the conjugate relationship between the first diffraction element and the second diffraction element; FIG. 10 is an explanatory diagram of another form showing tolerance for deviation from the conjugate relationship; Ray diagram of the optical system. The ray diagram of the optical system which concerns on a 1st modification. The ray diagram of the optical system which concerns on a 2nd modification. The ray diagram of the optical system which concerns on a 3rd modification. FIG. 11 is a ray diagram of an optical system according to a fourth modified example; Explanatory drawing of the 1st optical part in the optical system of a 4th modification. Explanatory drawing of the optical system which concerns on 2nd embodiment. Explanatory drawing of the optical system which concerns on 3rd embodiment. Explanatory drawing of the optical system which concerns on 4th embodiment. FIG. 4 shows different positions of the intermediate image in the horizontal and vertical directions; Explanatory drawing of the optical system which concerns on 5th embodiment. Explanatory drawing of the optical system which concerns on 6th embodiment. Explanatory drawing of the optical system which concerns on 7th embodiment. FIG. 11 is a diagram showing a substantially conjugate relationship between a first diffraction element and a second diffraction element in an optical system according to an eighth embodiment; FIG. 22 is an explanatory diagram of light emitted from the second diffraction element when the substantially conjugate relationship is shown in FIG. 21; FIG. 23 is an explanatory diagram showing how the light shown in FIG. 22 enters the eye;

(First embodiment)
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing below, the scale and angle of each layer and each member are made different from the actual ones in order to make each layer and each member recognizable.

FIG. 1 is an external view showing one aspect of the external appearance of the display device 100 of this embodiment. FIG. 2 is an external view showing another aspect of the external appearance of the display device 100. As shown in FIG. FIG. 3 is an explanatory diagram showing one aspect of the optical system 10 of the display device 100 shown in FIG. 1 to 3, the front-back direction with respect to the viewer wearing the display device is defined as the direction along the Z axis, and the front of the viewer wearing the display device as one side of the front-back direction is defined as the front side Z1. The rear side Z2 is the rear side of the observer wearing the display device. In addition, the horizontal direction with respect to the observer wearing the display device is the direction along the X axis, the right side of the observer wearing the display device as one side in the horizontal direction is the right side X1, and the other side in the horizontal direction is the display device. The left side of the observer who wears it is set as the left side X2. In addition, the vertical direction with respect to the viewer wearing the display device is the direction along the Y-axis direction, the upper side of the viewer wearing the display device is the upper side Y1 as one side in the vertical direction, and the display device is the other side in the vertical direction. A lower side Y2 is defined as the lower side of the observer wearing the device.

The display device 100 shown in FIG. 1 is a head-mounted display device, and includes a right-eye optical system 10a that causes the image light L0a to enter the right eye Ea, and a left-eye optical system 10a that causes the image light L0b to enter the left eye Eb. and an optical system 10b. The display device 100 is formed in a shape like eyeglasses, for example. Specifically, the display device 100 further includes a housing 90 that holds the right-eye optical system 10a and the left-eye optical system 10b. The display device 100 is mounted on the observer's head by the housing 90 .

The display device 100 includes a frame 91 as a housing 90, a temple 92a provided on the right side of the frame 91 and engaged with the observer's right ear, and a temple 92a provided on the left side of the frame 91 and attached to the observer's left ear. and a temple 92b to be locked. The frame 91 has storage spaces 91s on both sides, and each component such as an image light projection device constituting the optical system 10, which will be described later, is stored in the storage spaces 91s. The temples 92a and 92b are connected to the frame 91 by hinges 95 so as to be foldable.

The optical system for right eye 10a and the optical system for left eye 10b have the same basic configuration. Therefore, in the following description, the optical system 10a for the right eye and the optical system 10b for the left eye will be described as the optical system 10 without distinguishing between them.

Further, in the display device 100 shown in FIG. 1, the image light L0 is caused to travel in the horizontal direction along the X axis, but as shown in FIG. In some cases, the optical system 10 is arranged from the top of the head to the front of the eyes E.

A basic configuration of the optical system 10 of the display device 100 will be described with reference to FIG. FIG. 3 is an explanatory diagram showing one aspect of the optical system 10 of the display device 100 shown in FIG. In addition to the light L1 (solid line) of the specific wavelength of the image light L0, FIG. Illustrated.

As shown in FIG. 3, in the optical system 10, along the traveling direction of the image light L0 emitted from the image light generation device 31, there is a first optical section L10 having positive power and a second optical section L10 having positive power. An optical section L20, a third optical section L30 having positive power, and a fourth optical section L40 having positive power are arranged.

In this embodiment, the first optical section L10 having positive power is configured by the projection optical system 32. As shown in FIG. A second optical section L20 having positive power is composed of a reflective first diffraction element 50 . A third optical section L30 having positive power is configured by the light guide system 60 . A fourth optical section L40 having positive power is composed of a reflective second diffraction element 70 . In this embodiment, the first diffraction element 50 and the second diffraction element 70 are reflective diffraction elements.

Focusing on the traveling direction of the image light L0 in the optical system 10, the image light generator 31 emits the image light L0 toward the projection optical system 32, and the projection optical system 32 directs the incident image light L0 to the first direction. The light is emitted toward the diffraction element 50 , and the first diffraction element 50 emits the incident image light L 0 toward the light guide system 60 . The light guide system 60 emits the incident image light L0 to the second diffraction element 70, and the second diffraction element 70 emits the incident image light L0 toward the eye E of the observer.

In this embodiment, the image light generator 31 generates image light L0.
The image light generation device 31 may employ a mode having a display panel 310 such as an organic electroluminescence display element. According to this aspect, it is possible to provide the display device 100 that is small and capable of displaying high-quality images. In addition, the image light generating device 31 may employ a mode including an illumination light source (not shown) and a display panel 310 such as a liquid crystal display element that modulates the illumination light emitted from the illumination light source. According to this aspect, since the illumination light source can be selected, there is an advantage that the degree of freedom of the wavelength characteristics of the image light L0 is increased. Here, the image light generating device 31 can employ a mode having one display panel 310 capable of color display. Further, the image light generating device 31 may employ a mode having a plurality of display panels 310 corresponding to each color and a synthesizing optical system for synthesizing the image light of each color emitted from the plurality of display panels 310 . Furthermore, the image light generation device 31 may employ a mode in which the laser light is modulated by a micromirror device.

The projection optical system 32 is an optical system for projecting the image light L0 generated by the image light generation device 31 and is composed of a plurality of lenses 321 . In FIG. 3, the case where the number of lenses 321 in the projection optical system 32 is three is taken as an example, but the number of lenses 321 is not limited to this, and the projection optical system 32 may include four or more lenses 321. may be provided. Also, the lenses 321 may be bonded together to form the projection optical system 32 . Further, the lens 321 may be composed of a lens with a free curved surface.

The light guide system 60 has a lens system 61 into which the image light L0 emitted from the first diffraction element 50 is incident, and a mirror 62 that emits the image light L0 emitted from the lens system 61 in an oblique direction. doing. The lens system 61 is composed of a plurality of lenses 611 arranged in the front-rear direction along the Z-axis. The mirror 62 has a reflecting surface 620 obliquely inclined in the front-rear direction. In this embodiment, mirror 62 is a total reflection mirror. However, the mirror 62 may be a half mirror, and in this case, the range in which external light can be visually recognized can be widened.

Next, configurations of the first diffraction element 50 and the second diffraction element 70 will be described.
In this embodiment, the first diffraction element 50 and the second diffraction element 70 have the same basic configuration. The configuration of the second diffraction element 70 will be described below as an example.

FIG. 4A is an explanatory diagram of interference fringes 751 of the second diffraction element 70 shown in FIG. As shown in FIG. 4A, the second diffractive element 70 comprises a reflective volume holographic element 75, which is a partially reflective diffractive optical element. Thus, the second diffractive element 70 constitutes a partially transflective combiner. Therefore, since external light also enters the eye E via the second diffraction element 70, the observer can recognize an image in which the image light L0 formed by the image light generating device 31 and the external light (background) are superimposed. can be done.

The second diffraction element 70 faces the observer's eye E, and an incident surface 71 of the second diffraction element 70 on which the image light L0 is incident is a concave curved surface that is recessed in a direction away from the eye E. In other words, the incident surface 71 has a curved shape in which the central portion is recessed with respect to the peripheral portion in the incident direction of the image light L0. Therefore, the image light L0 can be efficiently condensed toward the eye E of the observer.

The second diffraction element 70 has interference fringes 751 with a pitch corresponding to a specific wavelength. The interference fringes 751 are recorded in the hologram photosensitive layer as a difference in refractive index, etc., and the interference fringes 751 are inclined in one direction with respect to the incident surface 71 of the second diffraction element 70 so as to correspond to a specific incident angle. there is Therefore, the second diffraction element 70 diffracts and deflects the image light L0 in a predetermined direction. The specific wavelength and specific incident angle correspond to the wavelength and incident angle of the image light L0. The interference fringes 751 having such a configuration can be formed by subjecting the holographic photosensitive layer to interference exposure using the reference light Lr and the object light Ls.

In this embodiment, the image light L0 is for color display. Therefore, the second diffraction element 70 has interference fringes 751R, 751G, and 751B formed at pitches corresponding to specific wavelengths. For example, the interference fringes 751R are formed at a pitch corresponding to, for example, the red image light LR with a wavelength of 615 nm within the wavelength range of 580 nm to 700 nm. The interference fringes 751G are formed at a pitch corresponding to the green image light LG with a wavelength of 535 nm, for example, within the wavelength range of 500 nm to 580 nm. The interference fringes 751B are formed at a pitch corresponding to the blue image light LB3 with a wavelength of 460 nm, for example, within the wavelength range of 400 nm to 500 nm. In such a configuration, in a state in which a holographic photosensitive layer having sensitivity corresponding to each wavelength is formed, reference light beams LrR, LrG and LrB and object light beams LsR, LsG and LsB of each wavelength are used to interfere with the holographic photosensitive layer. It can be formed by exposure.

A photosensitive material having a sensitivity corresponding to each wavelength is dispersed in the holographic photosensitive layer, and the reference beams LrR, LrG, and LrB and the object beams LsR, LsG, and LsB of each wavelength are used to interfere with the holographic photosensitive layer. By performing exposure, interference fringes 751 in which interference fringes 751R, 751G, and 751B are superimposed on one layer as shown in FIG. 4B may be formed. Further, spherical wave light may be used as the reference lights LrR, LrG, LrB and the object lights LsR, LsG, LsB.

The first diffractive element 50 , which has the same basic configuration as the second diffractive element 70 , comprises a reflective volume holographic element 55 . The first diffraction element 50 has an incident surface 51 on which the image light L0 is incident, which is a concavely curved surface. In other words, the incident surface 51 has a curved shape in which the central portion is recessed with respect to the peripheral portion in the incident direction of the image light L0. Therefore, the image light L0 can be efficiently deflected toward the light guide system 60 .

FIG. 5 is an explanatory diagram showing diffraction characteristics of the first diffraction element 50 and the second diffraction element 70 shown in FIG. FIG. 5 shows the difference in diffraction angle between a specific wavelength and peripheral wavelengths when a light beam is incident on one point on the volume hologram. In FIG. 5, when the specific wavelength is 531 nm, a solid line L526 indicates the deviation of the diffraction angle of light with a wavelength around 526 nm, and a dotted line L536 shows the deviation of the diffraction angle of light with a wavelength around 536 nm. There is. As shown in FIG. 5, even when rays are incident on the same interference fringes recorded in the hologram, rays with longer wavelengths are diffracted more and rays with shorter wavelengths are less diffracted. Therefore, when two diffraction elements, that is, the first diffraction element 50 and the second diffraction element 70 are used as in the present embodiment, the ray angles of the long-wavelength light and the short-wavelength light with respect to the specific wavelength are taken into account. If the light is not incident, proper wavelength compensation cannot be performed. That is, it becomes impossible to cancel the chromatic aberration generated by the second diffraction element 70 . Also, since the diffraction angle differs depending on the number of interference fringes, it is necessary to consider the interference fringes.

In the optical system 10 shown in FIG. 3, as described in Japanese Patent Application Laid-Open No. 2017-167181, the number of intermediate images formed between the first diffraction element 50 and the second diffraction element 70 and the number of intermediate images formed by the mirror 62 Since the incident direction and the like to the second diffraction element 70 are optimized according to whether the sum of the number of times of reflection is an odd number or an even number, wavelength compensation, that is, chromatic aberration can be canceled.

Specifically, the image light L0 incident on the first diffraction element 50 is deflected by being diffracted by the first diffraction element 50, as shown in FIG. At this time, the diffraction angle θ2 of the light L2 on the long wavelength _side with respect to the specific wavelength becomes larger _than the diffraction angle θ1 of the light L1 of the specific wavelength. Further, the diffraction angle θ3 of the light L3 _on the short wavelength side with respect to the specific wavelength is smaller _than the diffraction angle θ1 of the light L1 of the specific wavelength. Therefore, the image light L0 emitted from the first diffraction element 50 is deflected and dispersed for each wavelength.

The image light L0 emitted from the first diffraction element 50 enters the second diffraction element 70 via the light guide system 60 and is diffracted by the second diffraction element 70 to be deflected. At that time, in the optical path from the first diffraction element 50 to the second diffraction element 70, the formation of the intermediate image is performed once and the reflection by the mirror 62 is performed once. Therefore, when the angle between the image light L0 and the normal to the incident surface of the second diffraction element 70 is the incident angle, the light L2 on the long wavelength side with respect to the specific wavelength is incident at an incident angle θ ₁₁ with respect to the light L1 of the specific wavelength. , and the light L3 _on the short wavelength side with respect to the specific wavelength has an incident angle _.theta.13 smaller than the incident angle _.theta.11 of the light L1 with the specific wavelength. Further, as described above, the diffraction angle θ2 of the light L2 on the long wavelength _side with respect to the specific wavelength becomes larger _than the diffraction angle θ1 of the light L1 with the specific wavelength, and the light L3 on the short wavelength side with respect to the specific wavelength becomes larger. is smaller _{than the diffraction angle θ 1 of} the light L1 of the specific wavelength.

Therefore, the light L2 on the long wavelength side with respect to the specific wavelength is incident on the first diffraction element 50 at a larger incident angle than the light L1 with the specific wavelength, but the diffraction angle of the light L2 on the long wavelength side with respect to the specific wavelength is is larger than the diffraction angle of the light L1 of the specific wavelength. As a result, when the light L1 of the specific wavelength is emitted from the second diffraction element 70, the light L2 on the longer wavelength side and the light L1 of the specific wavelength are substantially parallel light. Become. On the other hand, the light L3 on the short wavelength side with respect to the specific wavelength enters the first diffraction element 50 at a smaller incident angle than the light L1 with the specific wavelength, but the light L3 on the short wavelength side with respect to the specific wavelength is smaller than the diffraction angle of the light L1 of the specific wavelength, as a result, the light L3 on the short wavelength side with respect to the specific wavelength and the light L1 of the specific wavelength are substantially parallel when emitted from the second diffraction element 70. light. In this manner, as shown in FIG. 3, the image light L0 emitted from the second diffraction element 70 is incident on the observer's eye E as substantially parallel light. Displacement is suppressed. Therefore, the chromatic aberration generated by the second diffraction element 70 can be canceled.

Next, the conjugate relationship between the first diffraction element 50 and the second diffraction element 70 will be described.
FIG. 6A is an explanatory diagram when the first diffraction element 50 and the second diffraction element 70 are in a conjugate relationship. 6B and 6C are explanatory diagrams when the first diffraction element 50 and the second diffraction element 70 are not in a conjugate relationship. FIGS. 7A and 7B are explanatory diagrams showing tolerances for deviations from the conjugate relationship between the first diffraction element 50 and the second diffraction element 70 shown in FIGS. 6B and 6C. In FIGS. 7A and 7B, a solid line Le indicates light with a specific wavelength, a dashed-dotted line Lf indicates light with a wavelength of -10 nm, and a two-dot chain line Lg indicates light with a wavelength of +10 nm. 6A to 6C, 7A and 7B, the first diffraction element 50, the second diffraction element 70, and the light guide system 60 are shown as transmissive so that the progress of light can be easily understood. , the second diffraction element 70 and the light guide system 60 are indicated by arrows.

As shown in FIG. 6A, when the first diffraction element 50 and the second diffraction element 70 are in a conjugate relationship, the divergent light emitted from point A (first position) of the first diffraction element 50 has a positive power. The light is condensed by the light guide system 60 and enters point B (second position corresponding to the first position) of the second diffraction element 70 . Therefore, the chromatic aberration due to diffraction generated at the B point can be compensated at the A point.

On the other hand, as shown in FIGS. 6B and 6C, when the first diffraction element 50 and the second diffraction element 70 are not in a conjugate relationship, the divergent light emitted from the point A of the first diffraction element 50 is The light is condensed by the light guide system 60 having positive power in the center, but crosses and enters at a position farther or nearer than point B on the second diffraction element 70 . Therefore, points A and B do not have a one-to-one relationship. Here, since the compensation effect is enhanced when the interference fringes in the region are uniform, the compensation effect is weakened when the first diffraction element 50 and the second diffraction element 70 are not in a conjugate relationship. On the other hand, it is difficult to compensate the entire projection area of the second diffraction element 70 with the first diffraction element 50 . Therefore, in the case of the embodiments shown in FIGS. 6B and 6C, since sufficient wavelength compensation cannot be performed, resolution degradation occurs.

In the case of light with a wavelength of ±10 nm with respect to the specific wavelength, there is an error of about ±0.4 mm from the point B where the light with the specific wavelength reaches, but the decrease in resolution is not conspicuous. As a result of examining such an allowable range, as shown in FIG. 7A, when light of a specific wavelength intersects before point B on the ideal second diffraction element 70 and is incident within a range of ±0.8 mm resolution loss is not noticeable. Further, as shown in FIG. 7B, when light of a specific wavelength crosses behind point B on the ideal second diffraction element 70 and is incident within a range of ±0.8 mm, the resolution is reduced. is inconspicuous. Therefore, even if the first diffraction element 50 and the second diffraction element 70 are not in a perfect conjugate relationship, they are in a substantially conjugate relationship, and when reaching within ±0.8 mm from the ideal point B, can tolerate a loss of resolution. That is, in the present embodiment, the conjugate relationship between the first diffraction element 50 and the second diffraction element 70 means that the incident position of light of a specific wavelength falls within the error range of ±0.8 mm from the ideal incident point. Say things.

FIG. 8 is a ray diagram in the optical system 10 of this embodiment. In FIG. 8 and the figures to be referred to later, each optical section arranged along the optical axis is indicated by a thick arrow. Further, a light ray emitted from one pixel of the image light generation device 31 is indicated by a solid line La, a principal ray emitted from an end of the image light generation device 31 is indicated by a dashed line Lb, and a conjugate relationship with the first diffraction element 50. A long broken line Lc indicates the position where . Here, the “intermediate image” is a place where rays (solid line La) emitted from one pixel gather, and the “pupil” is a place where principal rays (chain line Lb) of each angle of view gather. 8 shows the progress of light emitted from the image light generating device 31. As shown in FIG. In addition, in FIG. 8, in order to simplify the drawing, all the optical units are shown as transmissive type.

As shown in FIG. 8, in the optical system 10 of the present embodiment, along the optical path of the image light emitted from the image light generation device 31, the first optical section L10 having positive power and the first diffraction element 50 A second optical section L20 having positive power, a third optical section L30 having positive power, and a fourth optical section L40 having positive power and having a second diffraction element 70 are provided. there is

The focal length of the first optical section L10 is L/2, and the focal lengths of the second optical section L20, the third optical section L30, and the fourth optical section L40 are all L. Therefore, the optical distance from the second optical section L20 to the third optical section L30 is equal to the optical distance from the third optical section L30 to the fourth optical section L40.

In the optical system 10, a first intermediate image P1 of image light is formed between the first optical section L10 and the third optical section L30, and a pupil R1 is formed between the second optical section L20 and the fourth optical section L40. is formed, a second intermediate image P2 of the image light is formed between the third optical unit L30 and the fourth optical unit L40, and the fourth optical unit L40 collimates the image light to form an exit pupil R2. do. At that time, the third optical section L30 freely controls the image light emitted from the second optical section L20 as divergent light, convergent light, or parallel light, and causes the light to enter the fourth optical section L40. The second optical section L20 causes the image light emitted from the first optical section L10 to enter the third optical section L30 as convergent light. In the optical system 10 of this embodiment, the pupil R1 is formed in the vicinity of the third optical section L30 between the second optical section L2 and the fourth optical section L40. The vicinity of the third optical section L30 refers to a position between the second optical section L20 and the third optical section L30 that is closer to the third optical section L30 than the second optical section L20, or a position between the third optical section L30 and the fourth optical section L30. It means a position closer to the third optical part L30 than the fourth optical part L40 among the optical parts L40.

In addition, the third optical unit L30 converts the image light from one point of the image light generation device 31 into the light of the peripheral wavelength that is deflected by the first diffraction element 50 and deviated from the specific wavelength by the second diffraction element 70. Make it incident on the range. That is, the first diffraction element 50 and the second diffraction element 70 are in a conjugate or substantially conjugate relationship. Here, the absolute value of the magnification of the projection onto the second diffraction element 70 by the third optical section L30 of the first diffraction element 50 is from 0.5 times to 10 times, and the absolute value of such magnification is from 1 time to 5 times. Up to double is preferred.

Therefore, according to the optical system 10 of the present embodiment, the first intermediate image P1 of the image light is formed between the projection optical system 32 and the light guide system 60, and the pupil R1 is formed near the light guide system 60. , a second intermediate image P2 of the image light is formed between the light guide system 60 and the second diffraction element 70, and the second diffraction element 70 collimates the image light to form an exit pupil R2.

In the optical system 10 of this embodiment, the first intermediate image P1 is formed between the first optical section L10 (projection optical system 32) and the second optical section L20 (first diffraction element 50).

The optical system 10 of this embodiment satisfies the following four conditions (conditions 1, 2, 3, and 4).
Condition 1: A light ray emitted from one point of the image light generating device 31 is imaged as one point on the retina E0.
Condition 2: The entrance pupil of the optical system and the pupil of the eyeball are conjugate.
Condition 3: Properly arrange the first diffraction element 50 and the second diffraction element 70 so as to compensate for the peripheral wavelength.
Condition 4: The first diffraction element 50 and the second diffraction element 70 are in a conjugate or substantially conjugate relationship.

More specifically, as can be seen from the solid line La shown in FIG. 8, a light ray emitted from one point of the image light generating device 31 satisfies Condition 1 that an image is formed as one point on the retina E0. An observer can visually recognize one pixel. 8, the entrance pupil of the optical system 10 and the pupil E1 of the eye E are in a conjugate relationship (pupil conjugate). The entire area of the generated image can be visually recognized. Further, in order to satisfy the condition 3 that the first diffraction element 50 and the second diffraction element 70 are appropriately arranged so as to compensate for the peripheral wavelength, the chromatic aberration generated in the second diffraction element 70 is canceled by performing wavelength compensation. It is possible. Further, as can be seen from the long dashed line Lc shown in FIG. With the diffractive element 70, it is possible to make the light beams incident on the same place of the interference fringes, so that wavelength compensation can be properly performed. Therefore, deterioration of resolution of image light can be suppressed.

(first modification)
FIG. 9 is a ray diagram of the optical system 10A according to the first modification. As shown in FIG. 9, in the optical system 10A of this modified example, along the optical path of the image light emitted from the image light generation device 31, the first optical unit L10 (projection optical system 32) having positive power and the , comprising a first diffraction element 50, a second optical section L20 having positive power, a third optical section L30 (light guide system 60) having positive power, and a reflective second diffraction element 70, A fourth optical section L40 having positive power is provided.

The focal length of the first optical section L10 is 4L/11, the focal length of the second optical section L20 is 6L/11, the focal length of the third optical section L30 is 3L/4, and the focal length of the fourth optical section L40 has a focal length L. Therefore, the ratio of the optical distance from the second optical section L20 to the third optical section L30 to the optical distance from the third optical section L30 to the fourth optical section L40 is 1:2. The optical distance to the third optical section L30 is shorter than the optical distance from the third optical section L30 to the fourth optical section L40. Therefore, even when the optical system 10 is downsized, the field of view is less likely to be blocked by the third optical section L30.

In this modified example as well, similarly to the configuration of the first embodiment described with reference to FIG. A pupil R1 is formed near the third optical section L30, a second intermediate image P2 of the image light is formed between the third optical section L30 and the fourth optical section L40, and the fourth optical section L40 collimates the image light. It is photonized to form an exit pupil R2. In this modified example, as in the configuration of the first embodiment, the first intermediate image P1 is formed between the first optical section L10 (projection optical system 32) and the second optical section L20 (first diffraction element 50). be done.

Also in the optical system 10A of this modified example, similarly to the configuration of the first embodiment, the light ray emitted from one point of the image light generation device 31 satisfies Condition 1 that an image is formed as one point on the retina E0. . Moreover, the condition 2 that the entrance pupil of the optical system 10A and the pupil E1 of the eye E are in a conjugate relationship (pupil conjugate) is satisfied. Moreover, the condition 3 is satisfied that the first diffraction element 50 and the second diffraction element 70 are properly arranged. Further, in order to satisfy the condition 4 that the first diffraction element 50 and the second diffraction element 70 are in a conjugate or substantially conjugate relationship, the first diffraction element 50 and the second diffraction element 70 have the same interference fringes for light beams. chromatic aberration can be canceled by appropriately performing wavelength compensation. Therefore, deterioration of resolution of image light can be suppressed.

(Second modification)
FIG. 10 is a ray diagram of an optical system 10B according to a second modification. As shown in FIG. 10, in the optical system 10B of this modified example, along the optical path of the image light emitted from the image light generation device 31, the first optical unit L10 (projection optical system 32) having positive power and the , comprising a first diffraction element 50, a second optical section L20 having positive power, a third optical section L30 (light guide system 60) having positive power, and a reflective second diffraction element 70, A fourth optical section L40 having positive power is provided. In this modified example, a fifth optical section L50 is provided between the image light generation device 31 and the projection optical system 32 .

In this modified example as well, similarly to the configuration of the first embodiment described with reference to FIG. A pupil R1 is formed near the third optical section L30, a second intermediate image P2 of the image light is formed between the third optical section L30 and the fourth optical section L40, and the fourth optical section L40 collimates the image light. It is photonized to form an exit pupil R2. Also in this modified example, similarly to the configuration of the first embodiment, the first intermediate image P1 is positioned between the first optical section L10 (projection optical system 32) and the second optical section L20 (first diffraction element 50). It is formed. That is, in the configuration of the first embodiment described with reference to FIG. 8, when the position where the image light generation device 31 was arranged is assumed to be the virtual panel position, in the configuration shown in FIG. It is arranged on the side opposite to the first optical section L10 from the virtual panel position, and the distance between the image light generating device 31 and the first optical section L10 is the same as in the configuration of the first embodiment described with reference to FIG. It is longer than the distance between the image light generator 31 and the first optical section L10. Even in such a case, since the fifth optical section L50 is provided between the image light generating device 31 and the projection optical system 32, the light beam emitted from the image light generating device 31 is directed to the first optical section L10. After reaching the point, the configuration is the same as that of the first embodiment described with reference to FIG.

Therefore, in the optical system 10B of this modified example, as in the configuration of the first embodiment, the condition is that the light beam emitted from one point of the image light generation device 31 is imaged as one point on the retina E0. 1 is satisfied. Moreover, the condition 2 that the entrance pupil of the optical system 10B and the pupil E1 of the eye E are in a conjugate relationship (pupil conjugate) is satisfied. Moreover, the condition 3 is satisfied that the first diffraction element 50 and the second diffraction element 70 are properly arranged. Further, in order to satisfy the condition 4 that the first diffraction element 50 and the second diffraction element 70 are in a conjugate or substantially conjugate relationship, the first diffraction element 50 and the second diffraction element 70 have the same interference fringes for light beams. chromatic aberration can be canceled by appropriately performing wavelength compensation. Therefore, deterioration of resolution of image light can be suppressed.

(Third modification)
FIG. 11 is a ray diagram of an optical system 10C according to the third modification. As shown in FIG. 11, in the optical system 10C of this modified example, along the optical path of the image light emitted from the image light generation device 31, the first optical unit L10 (projection optical system 32) having positive power and the , comprising a first diffraction element 50, a second optical section L20 having positive power, a third optical section L30 (light guide system 60) having positive power, and a reflective second diffraction element 70, A fourth optical section L40 having positive power is provided.

In this modified example, similarly to the configurations of the first embodiment, the first modified example, and the second modified example, the first intermediate image P1 of the image light is formed between the first optical unit L10 and the third optical unit L30. , a pupil R1 is formed near the third optical section L30, a second intermediate image P2 of the image light is formed between the third optical section L30 and the fourth optical section L40, and the fourth optical section L40 forms the image light are collimated to form an exit pupil R2.

In this modified example, unlike the configurations of the first embodiment, the first modified example, and the second modified example, the first intermediate image P1 is formed by the second optical section L20 (the first diffraction element 50) and the third optical section L30 ( It is formed between the light guide system 60).

The optical system 10C also satisfies Condition 1 that a light ray emitted from one point of the image light generating device 31 is imaged as one point on the retina E0, similarly to the configuration of the first embodiment. Moreover, the condition 2 that the entrance pupil of the optical system 10C and the pupil E1 of the eye E are in a conjugate relationship (pupil conjugate) is satisfied. Moreover, the condition 3 is satisfied that the first diffraction element 50 and the second diffraction element 70 are properly arranged. Note that the optical system 10C of this modified example does not satisfy the condition 4 that the first diffraction element 50 and the second diffraction element 70 are in a conjugate or substantially conjugate relationship. Even in this case, the third optical unit L30 converts image light from one point of the image light generation device 31 into a predetermined range of the second diffraction element 70, which is deflected by the first diffraction element 50 and deviates from the specific wavelength. can be made incident on Therefore, the problem that the interference fringes are incident on different places is compensated for by the third optical section L30. Therefore, light with wavelengths around the specific wavelength can also be incident in the vicinity of the light with the specific wavelength, and chromatic aberration can be substantially canceled by performing wavelength compensation. Therefore, deterioration of resolution can be suppressed. That is, according to the optical system 10C of this modified example, although the wavelength compensation effect is weaker than that of the configuration of the first embodiment, etc., a certain wavelength compensation effect can be obtained when the aperture ratio is small.

(Fourth modification)
FIG. 12 is a ray diagram of an optical system 10D according to a fourth modification. FIG. 13 is an explanatory diagram of the first optical unit L10 according to this modified example. As shown in FIG. 12, in an optical system 10D of this modified example, similarly to the configuration of the first embodiment described with reference to FIG. , comprising a first diffraction element 50, a second optical section L20 having positive power, a third optical section L30 (light guide system 60) having positive power, and a reflective second diffraction element 70, A fourth optical section L40 having positive power is provided. Here, the image light generating device 31 has a laser light source 316, a collimating lens 317, and a micromirror device 318. By driving the micromirror device 318 to scan the laser light source 316, an image is generated. to generate Therefore, the image light generating device 31 itself forms the light of the angle of view.

For this reason, as shown in FIG. 13, in the configuration of the first embodiment described with reference to FIG. The image light generator 31 and lens L11 are replaced by the laser light source 316, collimating lens 317 and micromirror device 318 described above.

According to the optical system 10D, when the display device 100 is worn, even if the spectrum width of the laser light or the like changes due to temperature changes due to body temperature or the heat of the display device 100 itself, a high-quality image can be produced by wavelength compensation. can be displayed.

(Second embodiment)
Next, a display device according to a second embodiment will be described. This embodiment relates to another configuration in the optical system.

FIG. 14 is an explanatory diagram of the display device according to the second embodiment. The optical system 12 shown in FIG. 14 is arranged along the vertical direction as shown in FIG. , the projection optical system 32, the first diffraction element 50, and the light guide system 60 are arranged. In this embodiment, the light guide system 60 is composed of a mirror 62 having a reflecting surface 620 whose center is recessed from its periphery, and has positive power. The reflective surface 620 consists of a spherical surface, an aspherical surface, or a free-form surface. In this embodiment, the reflecting surface 620 is a free-form surface. The first diffraction element 50 is a transmissive volume holographic element integrated with a lens, and has positive power. Note that the first diffraction element 50 itself may be configured to have positive power.

In the optical system 12 of the present embodiment, as in the first modification described with reference to FIG. 9, along the optical path of the image light emitted from the image light generator 31, the first optical unit L10 (projection optical system 32), a second optical section L20 having a positive power and having a first diffraction element 50, a third optical section L30 having a positive power (mirror 62 of light guide system 60), A fourth optical section L40 having a positive power and including a reflective second diffraction element 70 is provided. Therefore, a first intermediate image P1 of image light is formed between the first optical section L10 and the third optical section L30, a pupil R1 is formed near the third optical section L30, and a pupil R1 is formed near the third optical section L30 and the fourth optical section L30. A second intermediate image P2 of the image light is formed between it and the optical section L40, and the fourth optical section L40 collimates the image light to form an exit pupil R2.

Here, the third optical section L30 is composed of a mirror 62 having positive power. Therefore, the divergent light diffracted by the second optical section L20 is condensed by the mirror 62. FIG. Further, the condensed light is incident on and near the point where the light of the specific wavelength of the fourth optical section L40 (second diffraction element 70) is incident.

In the optical system 12 of the present embodiment, similarly to the first modification 1 described with reference to FIG. 9, light rays emitted from one point of the image light generating device 31 are imaged as one point on the retina E0. satisfies condition 1 that Moreover, the condition 2 that the entrance pupil of the optical system 12 and the pupil E1 of the eye E are in a conjugate relationship (pupil conjugate) is satisfied. Moreover, the condition 3 is satisfied that the first diffraction element 50 and the second diffraction element 70 are properly arranged. Further, in order to satisfy the condition 4 that the first diffraction element 50 and the second diffraction element 70 are in a conjugate or substantially conjugate relationship, the first diffraction element 50 and the second diffraction element 70 have the same interference fringes for light beams. chromatic aberration can be canceled by appropriately performing wavelength compensation. Therefore, deterioration of resolution of image light can be suppressed.

(Third embodiment)
Next, a display device according to the third embodiment will be described. This embodiment relates to another configuration in the optical system.

FIG. 15 is an explanatory diagram of the display device according to the third embodiment. In the optical system 12 shown in FIG. 14, the first optical section L10 (projection optical system 32) and the second optical section L20 (first diffraction element 50) are separate bodies. 15, the first optical section L10 (projection optical system) and the second optical section L20 (first diffraction element 50) are integrated. More specifically, the first optical section L10 (projection optical system 32) is configured by a prism 85 having a plurality of reflecting surfaces 851 and 852, and the output surface 853 of the prism 85 is provided with the second optical section L20 (projection optical system 32). A transmissive first diffraction element 50) is constructed.

Other configurations are common to the second embodiment described with reference to FIG. Therefore, similarly to the mode shown in FIG. 14, chromatic aberration can be canceled by appropriately performing wavelength compensation. Therefore, deterioration of resolution of image light can be suppressed. Also, by using the prism 85, the first optical part L10 (the projection optical system 32) and the second optical part L20 (the first diffraction element 50) are integrated. It is possible to achieve

(Fourth embodiment)
Next, a display device according to the fourth embodiment will be described. This embodiment relates to another configuration in the optical system.

FIG. 16 is an explanatory diagram of a display device according to the fourth embodiment. The optical system 14 shown in FIG. 16 is located between the image light generating device 31 arranged on the temporal region and the second diffraction element 70 in front of the eye E, similarly to the embodiment described with reference to FIGS. A projection optical system 32, a first diffraction element 50, and a light guide system 60 are arranged at the bottom. In this embodiment, the projection optical system 32 has a rotationally symmetric lens 326 and a free-form surface lens 327 . The light guide system 60 is composed of a mirror 62 having a reflecting surface 620 whose center is recessed from its periphery, and has positive power. The reflective surface 620 consists of a spherical surface, an aspherical surface, or a free-form surface. In this embodiment, the reflecting surface 620 is a free-form surface. The first diffraction element 50 consists of a reflective volume holographic element. A mirror 40 is arranged in the middle of the optical path from the projection optical system 32 to the first diffraction element 50, and the projection optical system 32 projects an intermediate image (first intermediate image P1) on the reflecting surface of the mirror 40 or in the vicinity thereof. to form The mirror 40 has a concave curved reflecting surface 400 and has positive power. If the reflective surface 400 of the mirror 40 has positive power, the mirror 40 may be included as a component of the projection optical system 32 . That is, the first optical section L10 may include the mirror 40 when the mirror 40 has positive power. Note that the reflecting surface 400 of the mirror 40 may be flat and have no power.

In the optical system 14 configured in this manner, the first optical system having a positive power along the optical path of the image light emitted from the image light generation device 31, as in the first modification described with reference to FIG. A portion L10 (projection optical system 32), a second optical portion L20 having positive power and having first diffraction element 50, and a third optical portion L30 having positive power (mirror 62 of light guide system 60) , and a fourth optical section L40 having a positive power, which includes a reflective second diffraction element 70 .

In the optical system 14 of this embodiment, the first optical section L10 includes a plurality of lenses 326,327. Among the plurality of lenses 326 and 327, the lens 326 is the lens closest to the image light generating device 31 side. That is, the lens 326 corresponds to the "first lens".
In the optical system 14 of this embodiment, a pupil R0 is formed between the lens 326 and the lens 327 in the first optical section L10, a pupil R1 is formed near the third optical section L30, and a pupil R1 is formed near the third optical section L30. A second intermediate image P2 of the image light is formed between it and the fourth optical section L40, and the fourth optical section L40 collimates the image light to form an exit pupil R2.

A first intermediate image P1 and a second intermediate image P2 shown in FIG. 16 are intermediate images in the image light spread in the horizontal direction along the plane of the paper. Since the image light emitted from the image light generating device 31 spreads not only in the horizontal direction but also in the vertical direction perpendicular to the plane of FIG. 16, an intermediate image of the vertically spread image light also exists. In this embodiment, the vertical intermediate image is in the vicinity of the horizontal intermediate image.
Although the first intermediate image P1 is formed near the mirror 40 in the optical system 14 of the present embodiment, it may be formed in the first optical section L10 (projection optical system 32).

Further, the intermediate image in the horizontal direction and the intermediate image in the vertical direction may exist at different positions. FIG. 17 is a ray diagram when the position of the intermediate image is different in the horizontal direction and the vertical direction, and FIG. 17 is a ray diagram of image light in the horizontal direction and the vertical direction. In FIG. 17, reference _LH denotes horizontal image light, reference _P1H denotes a first intermediate image in horizontal image light _LH , reference _LV denotes vertical image light, and reference _P1V . denotes the first intermediate image in the vertical image light _LV . 17 schematically shows the image light generating device 31, the first optical section L10 (the projection optical system 32), and the mirror 40 arranged along the optical axis. In addition, in FIG. 17, the shapes of lenses 326 and 327 constituting the projection optical system 32 are also simplified.

As shown in FIG. 17, the first horizontal intermediate image P1H is positioned closer to the mirror 40, and the first vertical intermediate image _P1V is closer to the first intermediate image _P1H than the first horizontal intermediate image _P1H . It is located near the optical part L10.

FIG. 17 shows the case where the positions of the intermediate images are different in the horizontal direction and the vertical direction in the first intermediate image P1, but the positions in the second intermediate image may also be different in the horizontal direction and the vertical direction. Further, when the position of the intermediate image in the first intermediate image P1 differs between the horizontal direction and the vertical direction, one of the first intermediate image _P1H and the first intermediate image _P1V is formed in the first optical section L10. , the other of the first intermediate image P1- _H and the first intermediate image P1- _V may be formed outside the first optical section L10.

Also in the optical system 14 of the present embodiment, similarly to the first modified example described with reference to FIG. satisfies condition 1 that Moreover, the condition 2 that the entrance pupil of the optical system 10 and the pupil E1 of the eye E are in a conjugate relationship (pupil conjugate) is satisfied. Moreover, the condition 3 is satisfied that the first diffraction element 50 and the second diffraction element 70 are properly arranged. Further, in order to satisfy the condition 4 that the first diffraction element 50 and the second diffraction element 70 are in a conjugate or substantially conjugate relationship, the first diffraction element 50 and the second diffraction element 70 have the same interference fringes for light beams. chromatic aberration can be canceled by appropriately performing wavelength compensation. Therefore, deterioration of resolution of image light can be suppressed.

Further, among the members shown in FIG. 16, optical members having a combination of high dispersion and low dispersion are used for the plastic, glass, or the like constituting the translucent member. Further, since the mirror 62 is used in the third optical section L30, the first optical section L10 is in an achromatic state. Therefore, the position of the center of gravity of the optical system 14 is moved to the rear side Z2, which is advantageous in that the burden on the nose of the user can be reduced. As for the mirror 62, if a transflective mirror layer or an angle-selective mirror layer is formed on a transparent member such as transparent resin or glass by a sputtering method or the like, the external world can be visually recognized through the mirror 62.

(Fifth embodiment)
Next, a display device according to the fifth embodiment will be described. This embodiment relates to another configuration in the optical system.

FIG. 18 is an explanatory diagram of the display device according to the fifth embodiment. The optical system 15 shown in FIG. 18, like the fourth embodiment described with reference to FIG. Optical section L40), projection optical system 32 (first optical section L10), mirror 40, first diffraction element 50 (second optical section L20), and mirror 62 of light guide system 60 (third optical section L30 ) are placed.

In this embodiment, mirror 40 and mirror 62 are configured on different surfaces of common member 81 . Other configurations are common to the fourth embodiment shown in FIG. Therefore, wavelength compensation can be properly performed, as in the fourth embodiment shown in FIG. Moreover, since the mirror 40 and the mirror 62 are configured by the common member 81, it is possible to reduce the assembly tolerance. Also, since the number of molds for manufacturing the mirror can be reduced, the cost can be reduced.

(Sixth embodiment)
Next, a display device according to the sixth embodiment will be described. This embodiment relates to another configuration in the optical system.

FIG. 19 is an explanatory diagram of a display device according to the sixth embodiment. The optical system 16 shown in FIG. 19, like the fourth embodiment described with reference to FIG. Optical section L40), projection optical system 32 (first optical section L10), mirror 40, first diffraction element 50 (second optical section L20), and mirror 62 of light guide system 60 (third optical section L30 ) are placed.

In this embodiment, the mirror 62 and the second diffraction element 70 are arranged on different sides of a common member 82 . Other configurations are common to the fourth embodiment shown in FIG. Therefore, wavelength compensation can be properly performed, as in the fourth embodiment shown in FIG. In addition, since the mirror 62 and the second diffraction element 70 are formed by the common member 82, it is possible to reduce the assembly tolerance. Also, since the number of molds for manufacturing the mirror can be reduced, the cost can be reduced.

(Seventh embodiment)
Next, a display device according to the seventh embodiment will be described. This embodiment relates to another configuration in the optical system.

FIG. 20 is an explanatory diagram of a display device according to the seventh embodiment. The optical system 17 shown in FIG. 20, like the fourth embodiment described with reference to FIG. Optical section L40), projection optical system 32 (first optical section L10), mirror 40, first diffraction element 50 (second optical section L20), and mirror 62 of light guide system 60 (third optical section L30 ) are placed.

In this embodiment, mirror 40 , mirror 62 and second diffractive element 70 are arranged on different sides of common member 83 . Other configurations are common to the fourth embodiment shown in FIG. Therefore, wavelength compensation can be properly performed, as in the fourth embodiment shown in FIG. Moreover, since the mirror 40, the mirror 62, and the second diffraction element 70 are configured by the common member 83, it is possible to reduce the assembly tolerance. Also, since the number of molds for manufacturing the mirror can be reduced, the cost can be reduced.

(Eighth embodiment)
Next, a display device according to the eighth embodiment will be described. This embodiment relates to another configuration in the optical system. In the optical system of this embodiment, the first diffraction element 50 and the second diffraction element 70 are in a substantially conjugate relationship. The substantially conjugate relationship between the first diffraction element 50 and the second diffraction element 70 will be described below.

FIG. 21 is an explanatory diagram showing a substantially conjugate relationship between the first diffraction element 50 and the second diffraction element 70 in the optical system 18 of this embodiment. FIG. 22 is an explanatory diagram of light emitted from the second diffraction element 70 in the substantially conjugate relationship shown in FIG. FIG. 23 is an explanatory diagram showing how the light shown in FIG. 22 enters the eye E. As shown in FIG. In FIG. 21, light of a specific wavelength is indicated by a solid line Le, light of a wavelength of -10 nm is indicated by a dashed line Lf, and light of a wavelength of +10 nm is indicated by a two-dot chain line Lg. FIG. 23 shows, on the leftmost side of the drawing, light with a specific wavelength of −10 nm (light indicated by the dashed-dotted line Lf in FIG. 22) entering the eye E, and on the far right side of the drawing, Light with a wavelength of a specific wavelength of +10 nm (light indicated by a two-dot chain line Lg in FIG. 22) is incident on the eye E. In the meantime, light with a wavelength changed from the specific wavelength of −10 nm to the specific wavelength of +10 nm enters the eye. The state of incidence on E is shown. Although FIG. 23 does not show how the light of the specific wavelength is incident on the eye E, the appearance of the light of the specific wavelength being incident on the eye E is shown in the third from the left and the fourth from the left. It will be an intermediate state with the state shown.

In the above embodiment and the like, it is preferable that the first diffraction element 50 and the second diffraction element 70 are in a conjugate relationship. 70 are in a substantially conjugate relationship. In this case, as shown in FIG. 21, light of peripheral wavelengths deviated from the specific wavelength is incident on the second diffraction element 70 in a different state. Here, in the second diffraction element 70, the closer to the optical axis, the smaller the number of interference fringes, and the weaker the light bending force. For this reason, if light with longer wavelengths is incident on the optical axis side and light with shorter wavelengths is incident on the edge, light of a specific wavelength and light of peripheral wavelengths are collimated. An effect similar to compensation can be obtained.

In this case, since the position of the light beam is shifted depending on the wavelength, the diameter of the light beam incident on the pupil increases from the diameter φa to the diameter φb as shown in FIG. FIG. 23 shows the state of the light intensity incident on the pupil at that time. As can be seen from FIG. 23, the pupil cannot be filled in the vicinity of the specific wavelength, but the peripheral wavelength light can fill the pupil diameter because it is incident on a position shifted from the specific wavelength light. As a result, the observer can obtain advantages such as easier viewing of the image.

[Application to other display devices]
Although the head-mounted display device 100 has been exemplified in the above embodiment, the present invention may be applied to a head-up display, a handheld display, an optical system for a projector, and the like.

10, 10A, 10B, 10C, 10D, 12, 13, 14, 15, 16, 17, 18... optical system, 10a... optical system for right eye, 10b... optical system for left eye, 31... image light generating device, 32... Projection optical system 40, 62... Mirror 50... First diffraction element 55, 75... Reflective volume holographic element 60... Light guide system 61... Lens system 70... Second diffraction element 85... Prism 91 Front portion 100 Display device 310 Display panel 316 Laser light source 317 Collimating lens 318 Micromirror device L10 First optical unit L20 Second optical unit L2 Second 2 optical section lights, L30... 3rd optical section, L40... 4th optical section, P1... 1st intermediate image, P2... 2nd intermediate image, R0, R1... pupil, R2... exit pupil.

Claims (11)

Along the optical path of the image light emitted from the image light generation device,
a first optical section having positive power;
a second optical section having a first diffraction element and having positive power;
a third optical section having positive power;
a fourth optical section having a second diffraction element and having positive power;
with
In the optical path, the first optical unit is provided between the image light generating device and a first intermediate image of the image light,
In the optical path, the second optical section is emitted from the first optical section and the image light generation device .
provided between a pupil where the principal rays of the image light that are formed are gathered ,
In the optical path, the third optical section is provided between the second optical section and a second intermediate image of the image light,
In the optical path, the fourth optical section is provided between the third optical section and the exit pupil ,
A display device , wherein the first diffraction element and the second diffraction element are in a conjugate relationship . The display device according to claim 1,
A display device, wherein the second optical section is provided between the first intermediate image and the pupil in the optical path. The display device according to claim 1 or 2,
The display device, wherein the third optical section causes the image light emitted from the second optical section to enter the fourth optical section as divergent light. The display device according to claim 3 ,
The display device, wherein the second optical section causes the image light emitted from the first optical section to enter the third optical section as convergent light. The display device according to claim 3 or 4 ,
the incidence surface of the second diffraction element is a concave curved surface in which the central portion is concave with respect to the peripheral portion;
The display device, wherein the second diffraction element collimates the image light emitted from the third optical section. In the display device according to any one of claims 1 to 5 ,
A display device, wherein the absolute value of the magnification of the projection of the first diffraction element onto the second diffraction element by the third optical section is from 0.5 times to 10 times. The display device according to claim 6 ,
A display device, wherein the absolute value of the magnification is from 1 to 5 times. In the display device according to any one of claims 1 to 7 ,
A display device, wherein an optical distance between the first diffraction element and the third optical section is shorter than an optical distance between the third optical section and the second diffraction element. In the display device according to any one of claims 1 to 8 ,
The light emitted from the first position in the first diffraction element is incident within a range of ±0.8 mm with respect to the second position corresponding to the first position in the second diffraction element. display device. Along the optical path of the image light emitted from the image light generation device,
a first lens;
a second lens;
a first diffraction element having positive power and diffracting the image light;
a mirror that has positive power and reflects the image light;
a second diffraction element having positive power and diffracting the image light,
In the optical path, the first lens is provided between the image light generator and a first intermediate image of the image light,
In the optical path, the first diffractive element exits from the second lens and the image light generator .
provided between a pupil where the principal rays of the projected image light converge ,
In the optical path, the mirror is provided between the first diffraction element and a second intermediate image of the image light,
In the optical path, the second diffraction element is provided between the mirror and the exit pupil ,
A display device , wherein the first diffraction element and the second diffraction element are in a conjugate relationship . The display device according to claim 10 ,
A display device, wherein the second lens is provided between the first diffraction element and the first intermediate image.

Images