JP4543747B2 - Image display device - Google Patents

Description

  The present invention relates to an image display device suitable for use as, for example, a head-mounted display. Specifically, in the present invention, a transmissive diffractive optical element is provided on the pupil side surface of the spectacle lens and a reflective diffractive optical element is provided on the surface opposite to the pupil side to transmit light emitted from the image display element. By using the diffractive optical element, spectacle lens, reflective diffractive optical element, spectacle lens and transmissive diffractive optical element as light emitted to the pupil, the light utilization efficiency can be increased and the angle of view can be increased. The present invention relates to an image display device that can increase the magnification.

  Conventionally, for example, an image display device used as a head-mounted display or the like has been proposed. Some image display apparatuses of this type include a virtual image observation optical system that observes a display image of an image display element as a virtual image.

  For example, Patent Document 1 describes an image display device 200 as shown in FIG. The image display device 200 includes an image display element 201 formed of a liquid crystal display (LCD), a half mirror 202, and a concave mirror 203. Light emitted from the image display element 201 is incident on the half mirror 202. The reflected light reflected by the half mirror 202 enters the concave mirror 203. The reflected light reflected by the concave mirror 203 is incident on the half mirror 202 again. The transmitted light that has passed through the half mirror 202 is incident on the pupil 204.

  Further, for example, Patent Document 2 describes an image display device 300 as shown in FIG. The image display device 300 includes a light emitting diode (LED) 301, a lens 302, a transmissive liquid crystal display 303, a prism 304, and a reflective holographic optical element 305.

  The light emitted from the light emitting diode 301 is uniformly irradiated on the entire surface of the LCD 303 by the lens 302. The LCD 303 modulates the light irradiated on the entire surface for each pixel and displays an image. The emitted light emitted from the LCD 303 is incident on the prism 304, reflected by the inner surface of the prism 304 a predetermined number of times, and then incident on the reflective holographic optical element 305 and diffracted. The diffracted light from the optical element 305 passes through the prism 304 and enters the pupil 306.

JP 2000-221899 A (see page 2, FIG. 7) JP 2001-305476 A (refer to pages 4 to 5 and FIG. 2)

  In the image display device 200 shown in FIG. 9, since the light emitted from the image display element 201 is incident on the pupil 204 after passing through the half mirror 202 twice, the light utilization efficiency is 25% at the maximum. Is about 20%. In addition, when the concave mirror 203 is a half mirror, a see-through structure is obtained, and the other side of the optical component can be seen through. However, in this case, the light utilization efficiency on the other side is 25% at the maximum. In this case, the light use efficiency of the emitted light emitted from the image display element 201 is 12.5% at the maximum.

  In the image display apparatus 300 shown in FIG. 10, the reflected light reflected by the inner surface of the prism 304 a predetermined number of times is finally incident on the reflective holographic optical element 305 and diffracted, and the diffracted light enters the pupil 306. Is done. For this reason, when the angle of view θ is increased, the reflection type holographic optical element 305 needs to have a larger diffraction capability, and thus there is a problem that the angle of view θ cannot be increased very much.

  An object of the present invention is to increase the magnification by increasing the angle of view by increasing the light utilization efficiency.

  An image display device according to the present invention includes an image display element, a spectacle lens, a transmission type diffractive optical element provided on a first surface that is a pupil side surface of the spectacle lens, and a first surface of the spectacle lens. And a reflection type diffractive optical element provided on a second surface opposite to the surface, and light emitted from the image display element is transmitted through the transmission type diffractive optical element, spectacle lens, reflection type diffractive optical element, and spectacles. Light is emitted to the pupil through a lens and a transmission type diffractive optical element sequentially.

  In the present invention, a transmission type diffractive optical element is provided on the pupil side surface (first surface) of the spectacle lens. A reflective diffractive optical element is provided on the surface (second surface) opposite to the pupil side of the spectacle lens. Then, light emitted from the image display element is sequentially emitted through the transmission type diffractive optical element, the spectacle lens, the reflection type diffractive optical element, the spectacle lens, and the transmission type diffractive optical element to be output to the pupil. Thereby, the user can view the image displayed on the image display element as a virtual image.

  For example, light emitted from the image display element is incident on the transmissive diffractive optical element at a diffracted angle, and after being diffracted by the transmissive diffractive optical element, enters the spectacle lens as incident light from the first surface. Is done. This incident light is emitted as emitted light from the second surface of the spectacle lens. The emitted light is diffracted and reflected by the reflective diffractive optical element, and then enters the spectacle lens as incident light from the second surface. This incident light is emitted as emitted light from the first surface of the spectacle lens. The emitted light is incident on the transmissive diffractive optical element at an angle that is not diffracted, passes through the transmissive diffractive optical element without being diffracted, and is emitted from the transmissive diffractive optical element as emitted light to the pupil.

  Further, for example, light emitted from the image display element is incident on the transmission type diffractive optical element at an angle that is not diffracted, and after passing through the transmission type diffractive optical element, is incident on the spectacle lens as incident light from the first surface. The This incident light is emitted as emitted light from the second surface of the spectacle lens. The emitted light is diffracted and reflected by the reflective diffractive optical element, and then enters the spectacle lens as incident light from the second surface. This incident light is emitted as emitted light from the first surface of the spectacle lens. The emitted light is incident on the transmissive diffractive optical element at a diffracted angle, diffracted by the transmissive diffractive optical element, and emitted from the transmissive diffractive optical element as emitted light to the pupil.

  In this way, the light emitted from the image display element is incident on the user's pupil via the transmission type diffractive optical element, the spectacle lens, and the reflection type diffractive optical element, as compared with the case using a half mirror. , The light utilization efficiency is increased. In addition, the light emitted from the image display element is diffracted by the transmission type diffractive optical element and the reflection type diffractive optical element and then incident on the user's pupil. A large diffraction capability of each element is not required, so that the angle of view can be increased and the magnification can be increased.

  Further, for example, an imaging optical element is arranged between the image display element and the transmission type diffractive optical element, and the light emitted from the image display element is condensed at the intermediate imaging point by the imaging optical element. Later, it diverges and enters the transmissive diffractive optical element. In this case, when an optical system that forms an image on the display surface of the image display element when a ray at the pupil position, for example, a parallel ray is traced backward, is formed, an image formed at the intermediate image point is formed. It is only necessary to design the imaging optical element so as to correct the various optical aberrations generated by the existing transmissive diffractive optical element, spectacle lens, and reflective diffractive optical element and form an image on the display surface of the image display element. . In this case, in practice, the image is formed with an aberration that corrects various optical aberrations generated by the transmissive diffractive optical element, the spectacle lens, and the reflective diffractive optical element at the intermediate image forming point by the imaging optical element. Imaged.

  For example, at least one of the first surface and the second surface of the spectacle lens is a curved surface. Thereby, a lens effect can be given to the first surface and the second surface, the spread of the light beam can be suppressed, and the enlargement of the imaging optical element can be reduced. For example, if the curved surface is a cylindrical curved surface having a vertical or horizontal axis, the spread of the light bundle in the horizontal direction or the vertical direction can be suppressed, and the first and second surfaces of the spectacle lens can be suppressed. The transmission type diffractive optical element and the reflective type diffractive optical element can be easily applied to the surface.

  For example, when it is configured by an optical system that forms an image on the display surface of the image display element when a ray at the pupil position, for example, a parallel ray is traced backward, the wavelength dispersion caused by diffraction in the reflective diffractive optical element By generating reverse wavelength dispersion by diffraction in the transmission-type diffractive optical element, the color-dispersed light beam is condensed, for example, at an intermediate image forming position. Thereby, chromatic aberration generated by diffraction is canceled out.

  For example, a transmissive diffractive optical element and a reflective diffractive optical element are configured by a single diffractive layer having diffraction efficiency for a plurality of wavelength bands. In addition, for example, the transmissive diffractive optical element and the reflective diffractive optical element are configured by a plurality of diffractive layers, and the diffractive layers have diffraction efficiencies for different wavelength bands.

  For example, a transmissive diffractive optical element and a reflective diffractive optical element have diffraction efficiencies for a red wavelength band, a green wavelength band, and a blue wavelength band, respectively, in the visible light region. The As a result, the red component, the green component, and the blue component constituting the light emitted from the image display element can be diffracted by the transmissive diffractive optical element and the reflective diffractive optical element, respectively, and each color component can be incident on the user's pupil. The user can perceive a color image.

  For example, each of the transmissive diffractive optical element and the reflective diffractive optical element includes a first layer having diffraction efficiency with respect to the red wavelength band, and a second layer having diffraction efficiency with respect to the green wavelength band. And a third layer having diffraction efficiency with respect to the blue wavelength band. Further, for example, each of the transmission type diffractive optical element and the reflection type diffractive optical element has a first layer having diffraction efficiency for the red wavelength band and a second layer having diffraction efficiency for the green to blue wavelength band. It consists of layers. As a result, transmission-type diffractive optical elements and reflective-type diffractive optical elements can be obtained that are optimized for each wavelength band.

  For example, the transmissive diffractive optical element is a transmissive holographic optical element. In this case, for example, the transmissive holographic optical element is composed of a single hologram layer having diffraction efficiency for a plurality of wavelength bands. In this case, for example, the transmissive holographic optical element is an arbitrary It is composed of a plurality of hologram layers having diffraction efficiency with respect to the wavelength band. Here, by imparting polarization selectivity to the transmissive holographic optical element, for example, either p-polarized light or s-polarized light can be selectively diffracted.

  For example, the reflective diffractive optical element is a reflective holographic optical element. In this case, for example, the reflective holographic optical element is constituted by a single hologram layer having diffraction efficiency for a plurality of wavelength bands. In this case, for example, the reflective holographic optical element is an arbitrary It is composed of a plurality of hologram layers having diffraction efficiency with respect to the wavelength band.

  According to the present invention, the transmission-type diffractive optical element is provided on the pupil side surface of the spectacle lens and the reflection-type diffractive optical element is provided on the surface opposite to the pupil side. The diffractive optical element, spectacle lens, reflective diffractive optical element, spectacle lens, and transmissive diffractive optical element are used to sequentially emit light to the pupil. The light utilization efficiency can be increased and the angle of view can be increased. The magnification can be increased.

  A first embodiment of the present invention will be described. FIG. 1 shows a configuration of an image display apparatus 100 as the first embodiment. The image display device 100 includes, for example, an image display element 101 including a liquid crystal display (LCD), an imaging optical element 102, an eyeglass lens 103, a polarization selective transmission holographic optical element 104, and the like. And a reflection type holographic optical element 105. When the image display element 101 is a liquid crystal display, for example, a light emitting diode (LED: Liquid Crystal Display) is used as a light source.

  In the present embodiment, light emitted from the image display element 101 is p-polarized light that is linearly polarized light, and the transmissive holographic optical element 104 has diffraction efficiency with respect to this p-polarized light. . The light emitted from the image display element 101 may be s-polarized light that is linearly polarized light having a polarization plane orthogonal to p-polarized light, and the transmissive holographic optical element 104 may have diffraction efficiency with respect to s-polarized light. .

  The polarization selective transmissive holographic optical element 104 constitutes a transmissive diffractive optical element. The transmissive holographic optical element 104 is provided on the pupil side surface (first surface) of the spectacle lens 103. In this case, the transmissive holographic optical element 104 is attached to the first surface of the spectacle lens 103.

  The reflective holographic optical element 105 constitutes a reflective diffractive optical element. The reflective holographic optical element 105 is provided on a surface (second surface) opposite to the pupil-side surface (first surface) of the spectacle lens 103. In this case, the reflective holographic optical element 105 is attached to the second surface of the spectacle lens 103.

  The imaging optical element 102 includes imaging optical elements 102a to 102c. The imaging optical element 102 is disposed between the image display element 101 and the transmissive holographic optical element 104. In this case, the light emitted from the image display element 101 is condensed by the imaging optical element 102 at the intermediate imaging point P and then diverges and enters the transmissive holographic optical element 104.

  The image display apparatus 100 is configured by an optical system that forms an image on the display surface of the image display element 101 when a ray at the position of the user's pupil 106, for example, a parallel ray is traced back. Considering this reverse ray tracing, the imaging optical element 102 is composed of a transmissive holographic optical element 104, a spectacle lens 103, and a reflective holographic optical element 105 existing in an image formed at the intermediate imaging point P. It is designed to correct various generated optical aberrations and form an image on the display surface of the image display element 101. In this case, in practice, the imaging optical element 102 corrects various optical aberrations generated by the transmissive holographic optical element 104, the spectacle lens 103, and the reflective holographic optical element 105 at the intermediate imaging point P. An image is formed with

  At least one of the first surface and the second surface of the spectacle lens 103 is a curved surface so as to have a lens effect. Thereby, the spread of the light beam can be suppressed, and the enlargement of the imaging optical element 102 can be prevented. For example, the curved surface is a cylindrical curved surface having a vertical or horizontal axis. In this case, the spread of the light beam in the horizontal direction or the vertical direction can be suppressed, and the transmissive holographic optical element 104 and the reflective holographic optical element 105 on the first surface and the second surface of the spectacle lens 103 can be suppressed. It is also easy to adhere to.

  As shown in FIG. 2, the light emitted from the image display element 101 is incident on the transmissive holographic optical element 104 via the imaging optical element 102 (not shown in FIG. 2). The position, angle, etc. of the transmissive holographic optical element 104 are set so that the angle is diffracted by the transmissive holographic optical element 104.

  Further, as shown in FIG. 2, the diffracted light from the transmissive holographic optical element 104 is incident on the reflective holographic optical element 105 through the spectacle lens 103, and is diffracted and reflected. Light) is again incident on the transmissive holographic optical element 104 via the spectacle lens 103, and the reflection holographic optical is set so that the incident angle is not diffracted by the transmissive holographic optical element 104. The angle of diffracted light (reflected light) in the element 105 is set.

  Further, when considering the above-described reverse ray tracing, the wavelength dispersion opposite to the chromatic dispersion caused by the diffraction in the reflective holographic optical element 105 is generated by the diffraction in the transmissive holographic optical element 104, and the chromatically dispersed light beam is intermediate. The diffraction power of the transmissive holographic optical element 104 is set so that the light is condensed at the image forming position.

  Since the spectacle lens 103 is thin, the spread of chromatic dispersion caused by diffraction in the reflective holographic optical element 105 at the position of the transmissive holographic optical element 104 is small. For this reason, it is not always necessary to generate chromatic dispersion such that a chromatically dispersed light beam is collected at the imaging position by diffraction in the transmissive holographic optical element 104, and is generated by diffraction in the transmissive holographic optical element 104. The chromatic dispersion may maintain the spread of the chromatic dispersion caused by diffraction in the reflective holographic optical element 105 at the position of the transmissive holographic optical element 104 as it is.

  Further, when considering the above-described reverse ray tracing, the light flux diffracted and reflected by the reflective holographic optical element 105 and incident on the transmissive holographic optical element 104 is substantially parallel at all angles of view. The lens effect obtained by the reflection type holographic optical element 105 is optimized by changing the pitch of interference fringes of each part of the reflection type holographic optical element 105 stepwise. Thereby, the diffraction efficiency of the transmissive holographic optical element 104 is improved.

  The transmissive holographic optical element 104 and the reflective holographic optical element 105 have diffraction efficiency with respect to the red wavelength band, the green wavelength band, and the blue wavelength band, respectively, in the visible region. It is supposed to be. As a result, the red component, the green component, and the blue component constituting the light emitted from the image display element 101 can be diffracted by the transmission holographic optical element 104 and the reflection holographic optical element 105, respectively. Each color component can be incident, and the user can perceive a color image.

  In the present embodiment, the holographic optical elements 104 and 105 are respectively a red light diffraction holographic optical element 110R and 120R, a green light diffraction holographic optical element 110G and 120G, and a blue light diffraction holographic optical element 110B. , 120B are laminated. Here, the holographic optical elements 110R and 120R have diffraction efficiency with respect to the red wavelength band (for example, 620 nm to 640 nm) in the visible region. The holographic optical elements 110G and 120G have diffraction efficiency with respect to a green wavelength band (for example, 520 nm to 540 nm) in the visible region. The holographic optical elements 110B and 120B have diffraction efficiency with respect to a blue wavelength band (for example, 450 nm to 500 nm) in the visible region.

  In this case, the transmissive holographic optical element 104 is arranged in the order of the optical element 110R, the optical element 110B, and the optical element 110G from the eyeglass lens 103 side, as shown in FIG. Note that the optical element 110B, the optical element 110R, and the optical element 110G may be arranged in this order from the eyeglass lens 103 side.

  On the other hand, as shown in FIG. 3, the reflective holographic optical element 105 is arranged in the order of the optical element 120G, the optical element 120B, and the optical element 120R from the eyeglass lens 103 side. Note that the optical element 120G, the optical element 120R, and the optical element 120B may be arranged in this order from the eyeglass lens 103 side.

  The human eye is most sensitive to green light, red next to blue and lowest. As described above, in the holographic optical elements 104 and 105, the holographic optical element 110G having the diffraction efficiency with respect to the green wavelength band is arranged on the side on which the light beam to be diffracted is incident. The light beam to be incident is first incident on the optical elements 110G and 120G, and the green light beam is diffracted by the optical elements 110G and 120G without being affected by other optical elements. Therefore, the holographic optical elements 104 and 105 can accurately diffract a green light beam having high visibility, and the user can perceive an image with good resolution.

  Here, with reference to FIG. 4 and FIG. 5, the structure and manufacturing process of the polarization selective transmission holographic optical element 110 that constitutes the holographic optical elements 110R, 110G, and 110B described above will be described. This transmissive holographic optical element 110 is described in, for example, Japanese Patent Application Laid-Open No. 2002-221710.

  The transmissive holographic optical element 110 is formed by exposing a liquid crystal panel made of polymer dispersed liquid crystal (hereinafter referred to as “PDLC”) with interference fringes by a laser beam to form a hologram.

  That is, first, a PDLC 1 mixed with a polymer before photopolymerization (hereinafter referred to as “prepolymer”), a nematic liquid crystal, an initiator, a dye, and the like is paired with a pair of glass substrates on which a transparent electrode 2 is formed ( Alternatively, the film is sandwiched between films 3 and 3 to form a PDLC panel. At this time, the weight ratio of the nematic liquid crystal is about 30% of the whole. The layer thickness of the PDLC 1 (hereinafter referred to as “cell gap”) is in the range of about 2 μm to 15 μm, and is adapted to the specifications of the polarization selective transmission holographic optical element, for example, the wavelength band that gives diffraction efficiency. The optimum value is chosen.

  Next, in order to record interference fringes on the PDLC panel, object light 4 and reference light 5 from a laser light source (not shown) are irradiated to the PDLC panel, and light intensity (A) due to these interferences is generated. At this time, in a place where the interference fringes are bright, that is, a place where the energy of photons is large, the prepolymer in the PDLC undergoes photopolymerization and polymerizes due to the energy. For this reason, the prepolymer is supplied one after another from the peripheral portion, and as a result, the polymerized prepolymer is divided into a dense region and a sparse region. In regions where the prepolymer is sparse, the concentration of nematic liquid crystal is high. As a result, two regions of the polymer region 6 and the liquid crystal region 7 are formed.

  By the way, the polymer region 6 of the above-mentioned PDLC panel is isotropic with respect to the refractive index, and its value is, for example, 1.5. On the other hand, in the liquid crystal region 7 of the PDLC panel, nematic liquid crystal molecules 8 are arranged with their optical axes substantially perpendicular to the interface with the polymer region 6. Therefore, in this liquid crystal region 7, the refractive index has an incident polarization azimuth dependency. In this case, the ordinary ray is s when the incident light incident on the light incident surface 9 of the PDLC panel is considered. It is a polarization component.

  If the ordinary refractive index nlo of the liquid crystal region 7 is substantially equal to the refractive index np of the polymer region 6, for example, the refractive index difference is less than 0.01, the refractive index for the incident s-polarized component. The modulation of is very small and has little diffraction efficiency. In general, the difference Δn between the ordinary ray refractive index nlo and the extraordinary ray refractive index nle of the nematic liquid crystal is about 0.1 to 0.2, so that the p-polarized component having the same incident direction as the s-polarized component is high. A difference in refractive index is generated between the molecular region 6 and the liquid crystal region 7, functions as a phase modulation hologram, and has diffraction efficiency. This is the operation principle when no voltage is applied between the transparent electrodes 2 and 2 of the transmissive holographic optical element (H-PDLC panel) 110 (see FIG. 4).

  Next, an operation when a voltage is applied between the transparent electrodes 2 and 2 of the transmissive holographic optical element 110 as shown in FIG. 5 will be described. A power supply 11 is connected between the transparent electrodes 2 and 2 via a switch 10. By closing the switch 10, a voltage from the power source 11 is applied between the transparent electrodes 2 and 2. Thus, when an electric field is applied to the material inside the transmissive holographic optical element 110, the liquid crystal molecules 8 having dielectric anisotropy are oriented so that the optical axis is aligned with the electric field direction by an angle corresponding to the voltage. Can be changed. It is possible to control so as not to cause diffraction regardless of the polarization direction of incident light.

  Based on the principle described above, the transmissive holographic optical element 110 is switched to two states, a state in which only the p-polarized component of the incident light is diffracted and a state in which the polarized component in all directions of the incident light is not diffracted. Is possible.

  Note that the reflection type holographic optical elements constituting the holographic optical elements 120R, 120G, and 120B described above each use a photopolymer as a hologram photosensitive agent.

  The image display element 101 sequentially displays, for example, a red image, a green image, and a blue image with a predetermined period, for example, a period of 1/180 seconds. The image display element 101 emits red light, green light, and blue light, respectively, when a red image, a green image, and a blue image are displayed. A control unit (not shown) includes optical elements 110R, 110G, and 110B that constitute the transmissive holographic optical element 104, and displays only a p-polarized component when a red image, a green image, and a blue image are displayed on the image display element 101, respectively. Is in a state of diffracting, and in other cases, the polarization component in all directions is not diffracted.

  In this image display device 100, the emitted light (p-polarized light) emitted from the image display element 101 is converged at the intermediate image formation point P by the imaging optical element 102 and then diverges, thereby transmitting holographic optics. The light is incident on the element 104 at a diffracted angle and is diffracted. The diffracted light from the transmissive holographic optical element 104 enters the spectacle lens 103 as incident light from the first surface (the surface on the pupil 106 side). The incident light passes through the spectacle lens 103 and is emitted as emitted light from the second surface (the surface opposite to the pupil 106 side). The emitted light is incident on the reflective holographic optical element 105, and is diffracted and reflected.

  The diffracted light (reflected light) from the reflective holographic optical element 105 enters the spectacle lens 103 as incident light from the second surface. The incident light passes through the spectacle lens 103 and is emitted as emitted light from the first surface. The emitted light is incident on the transmissive holographic optical element 104 at an angle that is not diffracted, passes through as it is, and enters the user's pupil 106. Thereby, the user can recognize the image displayed on the image display element 101 as a virtual image.

  Here, consider ray tracing in the direction opposite to the actual traveling direction of rays.

  It is assumed that a light beam (p-polarized light) having a predetermined angle of view θ is emitted from the pupil 106 as emitted light. The emitted light is incident on the transmissive holographic optical element 104 at an angle that is not diffracted, passes through as it is, and enters the spectacle lens 103 as incident light from the first surface. The incident light passes through the spectacle lens 103 and is emitted as emitted light from the second surface. The emitted light is incident on the reflective holographic optical element 105, and is diffracted and reflected. In the reflection type holographic optical element 105, the p-polarized component in the visible wavelength region in the red wavelength band, the green wavelength band, and the blue wavelength band is diffracted with an arbitrary power.

  The diffracted light (reflected light) from the reflective holographic optical element 105 enters the spectacle lens 103 as incident light from the second surface. The incident light passes through the spectacle lens 103 and is emitted as emitted light from the first surface. The exit light of the p-polarized component is incident on the transmissive holographic optical element 104 at an angle to be diffracted and is diffracted. In this transmissive holographic optical element 104, the p-polarized component in the visible wavelength region in the red wavelength band, the green wavelength band, and the blue wavelength band is diffracted with an arbitrary power.

  Then, the diffracted light from the transmissive holographic optical element 104 is condensed at the intermediate image forming point P, and then condensed again on the display surface of the image display element 101 via the image forming optical element 102. The Thereby, a light ray at the position of the pupil 106, for example, a parallel light ray is imaged on the display surface of the image display element 101.

  In the image display apparatus 100 shown in FIG. 1, the light emitted from the image display element 101 is incident on the user's pupil 106 through the spectacle lens 103 and the holographic optical elements 104 and 105. As described above, the light use efficiency can be increased as compared with the case using the half mirror, and the user can see a bright image. In other words, since the light use efficiency can be increased, the power consumption for making the user perceive a bright image can be kept low.

  That is, in the image display apparatus 100 shown in FIG. 1, the deterioration or attenuation of the light amount of the light emitted from the image display element 101 is caused by the diffraction efficiency of the holographic optical elements 104 and 105, the spectacle lens 103, the imaging optical element 102, and the holographic optical element. It occurs only due to absorption inside the graphic optical elements 104 and 105 and surface reflection in each optical component. Moreover, the diffraction efficiency of the polarization selective transmission holographic optical element 104 is as high as 90% or higher, and the diffraction efficiency of the reflective holographic optical element 105 is as high as 95% or higher. Therefore, there is little deterioration or attenuation of the light quantity of the emitted light from the image display element 101, and the light quantity observed by the user's pupil 106 is increased.

  Further, in the image display device 100 shown in FIG. 1, light from the other side of the spectacle lens 103 existing in front of the user's pupil 106 passes through the spectacle lens 103 and the holographic optical elements 104 and 105. The light enters the pupil 106. That is, in the image display apparatus 100 shown in FIG. 1, the light from the other side is not incident on the user's pupil 106 through the half mirror as in the prior art, and a bright see-through structure can be provided.

  In the image display device 100 shown in FIG. 1, the light emitted from the image display element 101 is diffracted by the transmission holographic optical element 104 and the reflection holographic optical element 105, and then is diffracted to the user's pupil 106. The holographic optical elements 104 and 105 can share the diffraction, and the holographic optical elements 104 and 105 are not required to have a large diffraction capability. Therefore, according to the image display apparatus 100 shown in FIG. 1, the angle of view θ can be increased and the magnification can be increased as compared with the conventional apparatus using only the reflective holographic optical element.

  In addition, the image display device 100 shown in FIG. 1 includes a transmissive holographic optical element 104 and a reflective holographic optical element 105, and when a ray at the position of the pupil 106, for example, a parallel ray is traced backward, The chromatic dispersion opposite to the chromatic dispersion caused by the diffraction in the reflective holographic optical element 105 is generated by the diffraction in the transmissive holographic optical element 104, and the chromatically dispersed light beam is condensed at the intermediate image forming position. Therefore, according to the image display apparatus 100 shown in FIG. 1, it is possible to cancel chromatic aberration caused by diffraction and improve image quality. This effect is particularly effective when a light emitting diode having a broad wavelength band for each of the three primary colors is used as the light source of the image display element 101.

  Further, in the image display device 100 shown in FIG. 1, since it is not necessary to make a plurality of reflections in the spectacle lens 103, the spectacle lens 103 can be made thin enough to be manufactured.

  In the image display apparatus 100 shown in FIG. 1, the transmission type holographic optical element 104 has a three-layer structure of holographic optical elements 110R, 110G, and 110B. A two-layer structure in which the holographic optical element 110R for red light diffraction and the holographic optical element 110GB for green / blue light diffraction are stacked may be employed. In the image display device 100 shown in FIG. 1, the reflective holographic optical element 105 has a three-layer structure of holographic optical elements 120R, 120G, and 120B. A two-layer structure in which the holographic optical element 120R for red light diffraction and the holographic optical element 120GB for green / blue light diffraction are stacked may be employed. In this case, the holographic optical elements 110R and 120R have diffraction efficiency with respect to the red wavelength band in the visible region, whereas the holographic optical elements 110GB and 120GB have a green to blue wavelength band in the visible region. It has a diffraction efficiency.

  In this case, the transmissive holographic optical element 104 is arranged in the order of the optical element 110R and the optical element 110GB from the eyeglass lens 103 side, as shown in FIG. On the other hand, as shown in FIG. 8, the reflective holographic optical element 105 is disposed in the order of the optical element 120GB and the optical element 120R from the spectacle lens 103 side.

  Thereby, in the holographic optical elements 104 and 105, the holographic optical elements 110GB and 120GB having the diffraction efficiency with respect to the green wavelength band are arranged on the side on which the light beam to be diffracted is incident. The beam bundle to be incident is first incident on the optical elements 110GB and 120GB, and the green beam bundle is diffracted by the optical elements 110GB and 120GB without being influenced by other optical elements. Therefore, the holographic optical elements 104 and 105 can accurately diffract a green light beam having high visibility, and the user can perceive an image with good resolution.

  Further, although not shown, each of the holographic optical elements 104 and 105 is a single layer of holographic optical elements for diffracting red, green, and blue light that has diffraction efficiency in the red to blue wavelength band in the visible region. It can also be a structure.

  Next explained is the second embodiment of the invention. FIG. 7 shows a configuration of an image display apparatus 100A as the second embodiment. In FIG. 7, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted as appropriate.

  The image display device 100A includes an image display element 101, an imaging optical element 102, an eyeglass lens 103, a polarization selective transmission holographic optical element 104, and a reflection holographic optical element 105. .

  The transmissive holographic optical element 104 constitutes a transmissive diffractive optical element. The holographic optical element 104 is provided on the pupil side surface (first surface) of the spectacle lens 103. In this case, the transmissive holographic optical element 104 is attached to the first surface of the spectacle lens 103.

  The reflective holographic optical element 105 constitutes a reflective diffractive optical element. The reflective holographic optical element 105 is provided on a surface (second surface) opposite to the pupil-side surface (first surface) of the spectacle lens 103. In this case, the reflective holographic optical element 105 is attached to the second surface of the spectacle lens 103.

  The imaging optical element 102 includes imaging optical elements 102d and 102e. The imaging optical element 102 is disposed between the image display element 101 and the transmissive holographic optical element 104. In this case, the light emitted from the image display element 101 is condensed by the imaging optical element 102 at the intermediate imaging point P and then diverges and enters the transmissive holographic optical element 104.

  The image display device 100 </ b> A includes an optical system that forms an image on the display surface of the image display element 101 when a ray at the position of the user's pupil 106, for example, a parallel ray is traced back. Considering this reverse ray tracing, the imaging optical element 102 is composed of a transmissive holographic optical element 104, a spectacle lens 103, and a reflective holographic optical element 105 existing in an image formed at the intermediate imaging point P. It is designed to correct various generated optical aberrations and form an image on the display surface of the image display element 101. In this case, in practice, the imaging optical element 102 corrects various optical aberrations generated by the transmissive holographic optical element 104, the spectacle lens 103, and the reflective holographic optical element 105 at the intermediate imaging point P. An image is formed with

  As shown in FIG. 8, the light emitted from the image display element 101 is incident on the transmissive holographic optical element 104 via the imaging optical element 102 (not shown in FIG. 8). The position, angle, etc. of the transmissive holographic optical element 104 are set so that the angle is not diffracted by the transmissive holographic optical element 104.

  Further, as shown in FIG. 8, the light transmitted through the transmissive holographic optical element 104 without being diffracted is incident on the reflective holographic optical element 105 through the spectacle lens 103, and is diffracted and reflected. The diffracted light (reflected light) is incident again on the transmissive holographic optical element 104 via the spectacle lens 103, so that the incident angle is an angle diffracted by the transmissive holographic optical element 104. The angle of diffracted light in the reflective holographic optical element 105 is set.

  Further, when considering the above-described reverse ray tracing, the wavelength dispersion opposite to the chromatic dispersion caused by the diffraction in the reflective holographic optical element 105 is generated by the diffraction in the transmissive holographic optical element 104, and the chromatically dispersed light beam is intermediate. The diffraction power of the transmissive holographic optical element 104 is set so that the light is condensed at the image forming position.

  The rest of the image display device 100A is configured similarly to the image display device 100 shown in FIG.

  In this image display device 100A, the emitted light (p-polarized light) emitted from the image display element 101 is converged at the intermediate image formation point P by the imaging optical element 102 and then diverges, thereby transmitting holographic optics. The light is incident on the element 104 at an angle that is not diffracted, passes through as it is, and enters the spectacle lens 103 as incident light from the first surface (the surface on the pupil 106 side). The incident light passes through the spectacle lens 103 and is emitted as emitted light from the second surface (the surface opposite to the pupil 106 side). The emitted light is incident on the reflective holographic optical element 105, and is diffracted and reflected.

  The diffracted light (reflected light) from the reflective holographic optical element 105 enters the spectacle lens 103 as incident light from the second surface. The incident light passes through the spectacle lens 103 and is emitted as emitted light from the first surface. The emitted light is incident on the transmissive holographic optical element 104 at an angle to be diffracted and is diffracted. The diffracted light from the transmissive holographic optical element 104 enters the user's pupil 106. Thereby, the user can recognize the image displayed on the image display element 101 as a virtual image.

  Here, consider ray tracing in the direction opposite to the actual traveling direction of rays.

  It is assumed that a light beam (p-polarized light) having a predetermined angle of view is emitted from the pupil 106 as emitted light. The emitted light is incident on the transmissive holographic optical element 104 at an angle to be diffracted and is diffracted. In this transmissive holographic optical element 104, the p-polarized component in the visible wavelength region in the red wavelength band, the green wavelength band, and the blue wavelength band is diffracted with an arbitrary power.

  The diffracted light from the transmissive holographic optical element 104 enters the spectacle lens 103 as incident light from the first surface. The incident light passes through the spectacle lens 103 and is emitted as emitted light from the second surface. The emitted light is incident on the reflective holographic optical element 105, and is diffracted and reflected. In the reflection type holographic optical element 105, the p-polarized component in the visible wavelength region in the red wavelength band, the green wavelength band, and the blue wavelength band is diffracted with an arbitrary power.

  The diffracted light (reflected light) from the reflective holographic optical element 105 enters the spectacle lens 103 as incident light from the second surface. The incident light passes through the spectacle lens 103 and is emitted as emitted light from the first surface. The emitted light is incident on the transmissive holographic optical element 104 at an angle that is not diffracted and is transmitted as it is.

  The emitted light from the holographic optical element 104 is condensed at the intermediate image forming point P, and then condensed again on the display surface of the image display element 101 via the image forming optical element 102. Thereby, a light ray at the position of the pupil 106, for example, a parallel light ray is imaged on the display surface of the image display element 101.

  In the image display device 100A shown in FIG. 7, the light emitted from the image display element 101 is diffracted and reflected by the reflective holographic optical element 105 and then diffracted by the transmissive holographic optical element 104 to be diffracted by the user's pupil 106. The light emitted from the image display element 101 is diffracted by the transmissive holographic optical element 104 and further diffracted by the reflective holographic optical element 105 to be incident on the pupil 106 of the user. Although the configuration is different from that of the image display apparatus 100 shown in FIG. 4, the other configurations are the same, and the same operational effects can be obtained.

  This invention can increase the light utilization efficiency, allows see-through, can make a spectacle lens thin, can increase the angle of view and increase the magnification, and can be used as a head-mounted display or the like. Suitable for use.

It is a side view which shows the structure of the image display apparatus as 1st Embodiment. It is a figure for demonstrating the diffraction in a transmissive | pervious holographic optical element and a reflective holographic optical element. It is a figure for demonstrating the structural example (3 layer structure) of a transmissive | pervious holographic optical element with respect to red, green, and blue color light, and the structural example (3 layer structure) of a reflective holographic optical element. It is a longitudinal cross-sectional view which shows the structure (voltage non-application state) of a polarization selective transmission type holographic optical element. It is a longitudinal cross-sectional view which shows the structure (voltage application state) of a polarization selective transmission type holographic optical element. It is a figure for demonstrating the structural example (2 layer structure) of a transmission type holographic optical element with respect to red, green, and blue color light, and the structural example (2 layer structure) of a reflection type holographic optical element. It is a side view which shows the structure of the image display apparatus as 2nd Embodiment. It is a figure for demonstrating the diffraction in a transmissive | pervious holographic optical element and a reflective holographic optical element. It is a side view which shows the structure of an example of the conventional image display apparatus. It is a side view which shows the structure of the other example of the conventional image display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100,100A ... Image display apparatus, 101 ... Image display element, 102 ... Imaging optical element, 103 ... Eyeglass lens, 104 ... Polarization selective transmission type holographic optical element, 105. ..Reflection-type holographic optical element 106: User's pupil 110: Polarization selective transmission holographic optical element

Claims (21)

An image display element;
Eyeglass lenses,
A transmission type diffractive optical element provided on a first surface which is a pupil side surface of the spectacle lens;
A reflective diffractive optical element provided on a second surface which is a surface opposite to the first surface of the spectacle lens;
The light emitted from the image display element is emitted to the pupil through the transmission diffractive optical element, the spectacle lens, the reflection diffractive optical element, the spectacle lens, and the transmission diffractive optical element sequentially. An image display device characterized by that. Light emitted from the image display element is incident on the transmissive diffractive optical element at a diffracted angle, diffracted by the transmissive diffractive optical element, and then incident on the spectacle lens from the first surface. As incident and
Incident light incident on the spectacle lens from the first surface is emitted as exit light from the second surface of the spectacle lens;
The light emitted from the second surface of the spectacle lens is diffracted and reflected by the reflective diffractive optical element, and then enters the spectacle lens as incident light from the second surface,
Incident light incident on the spectacle lens from the second surface is emitted as exit light from the first surface of the spectacle lens,
The light emitted from the first surface of the spectacle lens is incident on the transmissive diffractive optical element at an angle that is not diffracted, and is transmitted through the transmissive diffractive optical element without being diffracted. The image display device according to claim 1, wherein the image display device emits light from an element as light emitted to the pupil. Light emitted from the image display element is incident on the transmissive diffractive optical element at an angle that is not diffracted, and after passing through the transmissive diffractive optical element, enters the spectacle lens as incident light from the first surface. And
Incident light incident on the spectacle lens from the first surface is emitted as exit light from the second surface of the spectacle lens;
The light emitted from the second surface of the spectacle lens is diffracted and reflected by the reflective diffractive optical element, and then enters the spectacle lens as incident light from the second surface,
Incident light incident on the spectacle lens from the second surface is emitted as exit light from the first surface of the spectacle lens,
The light emitted from the first surface of the spectacle lens is incident on the transmissive diffractive optical element at a diffracted angle, diffracted by the transmissive diffractive optical element, and from the transmissive diffractive optical element. The image display device according to claim 1, wherein the image display device is emitted as light emitted to a pupil. An imaging optical element disposed between the image display element and the transmissive diffractive optical element;
The emitted light from the image display element is converged at an intermediate imaging point by the imaging optical element, and then diverges and enters the transmission type diffractive optical element. The image display device described. The image display device according to claim 1, wherein at least one of the first surface and the second surface of the spectacle lens is a curved surface. The image display device according to claim 5, wherein the curved surface is a cylindrical curved surface having a vertical or horizontal axis. Consists of an optical system that forms an image on the display surface of the image display element when the light ray at the position of the pupil is traced by a reverse ray.
The chromatic dispersion opposite to the chromatic dispersion caused by diffraction in the reflective diffractive optical element is generated by the transmissive diffractive optical element, and the light beam is condensed at an imaging position. Image display device. Consists of an optical system that forms an image on the display surface of the image display element when the light ray at the position of the pupil is traced by a reverse ray.
The chromatic dispersion opposite to the chromatic dispersion caused by diffraction in the transmissive diffractive optical element is generated by the reflective diffractive optical element, and the light beam is condensed at an imaging position. Image display device. The image display apparatus according to claim 1, wherein the transmissive diffractive optical element is configured by a single diffraction layer having diffraction efficiency for a plurality of wavelength bands. The image display apparatus according to claim 1, wherein the transmissive diffractive optical element includes a plurality of diffraction layers, and each of the plurality of diffraction layers has diffraction efficiency with respect to different wavelength bands. The image according to claim 1, wherein the transmissive diffractive optical element has diffraction efficiency with respect to a red wavelength band, a green wavelength band, and a blue wavelength band in a visible light region. Display device. The transmissive diffractive optical element includes a first layer having diffraction efficiency for the red wavelength band, a second layer having diffraction efficiency for the green wavelength band, and the blue wavelength band. The image display device according to claim 11, comprising: a third layer having diffraction efficiency. The transmission-type diffractive optical element includes a first layer having diffraction efficiency with respect to the red wavelength band and a second layer having diffraction efficiency with respect to the green to blue wavelength band. The image display device according to claim 11. The image display apparatus according to claim 1, wherein the transmissive diffractive optical element is a transmissive holographic optical element. 15. The image display device according to claim 14, wherein the transmissive holographic optical element is a deflection selective transmissive holographic optical element. The image display apparatus according to claim 1, wherein the reflective diffractive optical element includes a single diffraction layer having diffraction efficiency for a plurality of wavelength bands. The image display apparatus according to claim 1, wherein the reflective diffractive optical element includes a plurality of diffraction layers, and each of the plurality of diffraction layers has a diffraction efficiency with respect to different wavelength bands. The image according to claim 1, wherein the reflective diffractive optical element has diffraction efficiency with respect to a red wavelength band, a green wavelength band, and a blue wavelength band in a visible light region. Display device. The reflective diffractive optical element includes a first layer having diffraction efficiency for the red wavelength band, a second layer having diffraction efficiency for the green wavelength band, and the blue wavelength band. The image display device according to claim 18, further comprising a third layer having diffraction efficiency. The reflective diffractive optical element includes a first layer having diffraction efficiency with respect to the red wavelength band, and a second layer having diffraction efficiency with respect to the green to blue wavelength band. The image display apparatus according to claim 18, wherein: The image display apparatus according to claim 1, wherein the reflective diffractive optical element is a reflective holographic optical element.

Images