WO2010064582A1

WO2010064582A1 - Video display device and head-mounted display

Info

Publication number: WO2010064582A1
Application number: PCT/JP2009/070031
Authority: WO
Inventors: 靖谷尻
Original assignee: コニカミノルタホールディングス株式会社
Priority date: 2008-12-04
Filing date: 2009-11-27
Publication date: 2010-06-10

Abstract

Disclosed is a video display device and head-mounted display that reliably absorb video luminescence, by way of an analyzer, when a display is black, and allow observing a high-contrast video regardless of the location along the x-axis of the observer’s eyes. A polarizer, a liquid crystal element, and the analyzer are positioned within a plane of symmetry upon a system of axial asymmetry, such that a relative angle of either a relative angle between a surface of the polarizer and an element surface of the liquid crystal element, i.e., an angle of inclination α, and/or a relative angle between the surface of the analyzer and the element surface, i.e., an angle of inclination β, is less than a relative angle between an optical axis and a normal of the element surface, i.e. an angle of inclination θ. It is thereby possible, even with respect to the light from the liquid crystal element that moves toward a position that is misaligned along the x-axis from the center of the optical aperture, to treat the misalignment in either the direction of the axis of penetration of the polarizer or the direction of the axis of penetration of the analyzer as less than or equal to the misalignment in the direction of the slow axis of the liquid crystal when the display is black, and to reduce the angular differential between the slow axis of the liquid crystal when the display is black and the axis of penetration of either the polarizer or the analyzer.

Description

Video display device and head mounted display

The present invention relates to an image display device and a head-mounted display that allow an observer to observe a display image at the position of an optical pupil by guiding image light from an image display element to an optical pupil via an axially asymmetric eyepiece optical system. (Hereinafter also referred to as HMD).

Conventionally, various video display devices have been proposed that allow an observer to observe an image using a reflective display element (for example, a liquid crystal element having a ferroelectric liquid crystal). For example, in the apparatus of Patent Document 1, as shown in FIG. 21, light from a light source 101 is transmitted through at least a polarizer 102, a display element 103, an analyzer 104, and an axially asymmetric (rotationally asymmetric) eyepiece optical system 105. It leads to the optical pupil E. Thereby, at the position of the optical pupil E, the observer can observe a video (virtual image).

Japanese Unexamined Patent Publication No. 2000-249968 (see FIG. 1)

Incidentally, an axis that optically connects the center of the element surface of the display element 103 and the center of the optical pupil E is defined as an optical axis AX, and the optical axis direction when the optical path is expanded is defined as a Z direction. Two directions perpendicular to the Z direction are defined as an X direction and a Y direction, respectively. Under such a definition, the above-mentioned eyepiece optical system 105 is axially asymmetric in the YZ plane, and has the YZ plane as an axially asymmetric symmetry plane.

In the apparatus of Patent Document 1, the polarizer 102 and the analyzer 104 are arranged in the optical path in consideration of the relative angle with the element surface of the display element 103 in the YZ plane that is an axially asymmetric symmetry plane of the eyepiece optical system 105. It has not been done. For this reason, when the observer's pupil is at a position shifted in the X direction from the center of the optical pupil E, there arises a problem that black becomes weak and the contrast of the observation image is lowered.

That is, when the display element 103 is a liquid crystal element having a ferroelectric liquid crystal, the image is displayed in black when the display element 103 does not act as a phase plate (reciprocating half-wave plate). In the configuration using the reflective display element 103, the optical axis AX is inclined at an inclination angle other than perpendicular to the element surface of the display element 103 in the YZ plane, and the slow phase of the liquid crystal with respect to the optical axis AX. Since the axis is tilted in the YZ plane, the liquid crystal at the time of black display with respect to light from the display element 103 (hereinafter referred to as light toward the pupil end) heading to a position shifted in the X direction from the center of the optical pupil E is displayed. The direction of the slow axis slightly deviates (rotates) from the direction of the slow axis of the liquid crystal during black display with respect to light from the display element 103 toward the center of the optical pupil E (hereinafter referred to as light toward the center of the pupil). ).

At this time, if the relative angle between the polarizer 102 and the element surface of the display element 103 and the relative angle between the analyzer 104 and the element surface of the display element 103 are not set appropriately in the YZ plane, The angle difference between the slow axis of the liquid crystal at the time of black display and the transmission axis of the polarizer 102 and the angle difference between the slow axis of the liquid crystal at the time of black display and the transmission axis of the analyzer 104 are increased. As a result, the black display image light cannot be completely absorbed (shielded) by the analyzer 104 at the pupil end. That is, when an image is observed at a position deviated from the center of the optical pupil E in the X direction, black becomes weak due to light leakage at the analyzer 104, and the contrast of the observed image decreases.

The present invention has been made to solve the above-described problems, and its object is to provide at least one of a polarizer and an analyzer and an element surface of a liquid crystal element within an axially asymmetric symmetry plane of an eyepiece optical system. By appropriately setting the relative angle with respect to the image, it is possible to observe a high-contrast image by reliably absorbing the image light during black display by the analyzer regardless of the position of the observer's pupil in the X direction. It is to provide a video display device that can be used and an HMD including the video display device.

The image display apparatus of the present invention includes a reflective image display element that modulates light from a light source to display an image, an axially asymmetric illumination optical system that guides light from the light source to the image display element, and the image An image display device comprising an axially asymmetric eyepiece optical system for guiding image light from a display element to an optical pupil, wherein the image display element includes a liquid crystal element that modulates incident light for each pixel, and the light source. A polarizer that transmits light in a predetermined polarization direction to the liquid crystal element, and transmits light in a predetermined polarization direction among the light emitted from the liquid crystal element to the eyepiece optical system. An analyzer that guides the optical axis, and the optical axis is an axis that optically connects the center of the element surface of the liquid crystal element and the center of the optical pupil, the optical axis is axisymmetric with respect to the eyepiece optical system. In the symmetry plane (in the symmetry plane of the axially asymmetric system), with respect to the element plane Relative angle between the plane of the polarizer and the element surface within an axially asymmetric symmetry plane of the eyepiece optical system when the optical path is inclined along the optical axis and is inclined at an inclination angle other than right The relative angle of at least one of the relative angles between the analyzer surface and the element surface is less than the relative angle between the optical axis and the normal of the element surface.

The image display apparatus of the present invention includes a reflective image display element that modulates light from a light source to display an image, an axially asymmetric illumination optical system that guides light from the light source to the image display element, and the image An image display device comprising an axially asymmetric eyepiece optical system for guiding image light from a display element to an optical pupil, wherein the image display element includes a liquid crystal element that modulates incident light for each pixel, and the light source. A polarizer that transmits light in a predetermined polarization direction to the liquid crystal element, and transmits light in a predetermined polarization direction among the light emitted from the liquid crystal element to the eyepiece optical system. An analyzer that guides the optical axis, and the optical axis is an axis that optically connects the center of the element surface of the liquid crystal element and the center of the optical pupil, the optical axis is axisymmetric with respect to the eyepiece optical system. In the symmetry plane (in the symmetry plane of the axially asymmetric system), with respect to the element plane When the optical path is inclined at an inclination angle other than right and the optical path is developed along the optical axis, the plane of the polarizer and the plane of the analyzer are not parallel, and the plane of the polarizer and the liquid crystal element The relative angle between the element surface and the analyzer surface is equal to the relative angle between the element surface of the liquid crystal element.

In the video display device of the present invention, the analyzer is arranged to be in crossed Nicols with the polarizer, and in black display, the liquid crystal element maintains the polarization direction of the light transmitted through the polarizer, The analyzer is preferably configured to absorb light in the polarization direction.

In the image display device of the present invention, it is desirable that the transmission axis of the polarizer is parallel or perpendicular to the axially asymmetric plane of symmetry of the eyepiece optical system.

In the video display device of the present invention, when the optical path is developed along the optical axis, at least one of the surface of the polarizer and the surface of the analyzer is substantially parallel to the element surface of the liquid crystal element. Good.

In the video display device of the present invention, when an optical path is developed along the optical axis, an angle formed by the plane of the polarizer and the element plane of the liquid crystal element, and the plane of the analyzer and the element plane of the liquid crystal element It is desirable that the angle between the two is within 5 degrees.

In the image display device of the present invention, when the optical path is developed along the optical axis, the plane of the polarizer and the plane of the analyzer are both substantially parallel to the element plane of the liquid crystal element. Good.

In the image display device of the present invention, when the optical path is developed along the optical axis, the plane of the polarizer and the plane of the analyzer are not parallel, and the plane of the polarizer and the element plane of the liquid crystal element The relative angle between the surface of the analyzer and the element surface of the liquid crystal element may be equal.

In the video display device of the present invention, both the relative angle between the plane of the polarizer and the element surface, and the relative angle between the plane of the analyzer and the element surface are normal to the optical axis and the element surface. It may be less than the relative angle.

In the video display device of the present invention, it is preferable that the liquid crystal element has a ferroelectric liquid crystal.

In the video display device of the present invention, it is preferable that the illumination optical system is disposed outside the optical path from the liquid crystal element toward the eyepiece optical system, and reflects the light from the light source to the liquid crystal element.

In the video display device of the present invention, it is desirable that the relative angle between the optical axis and the normal of the element surface is 10 degrees or more.

In the video display device of the present invention, it is preferable that the video display element is disposed on one end side of the eyepiece optical system.

The head-mounted display (HMD) of the present invention is characterized by having the above-described video display device of the present invention and support means for supporting the video display device in front of the observer's eyes.

According to the present invention, light in a predetermined polarization direction among the light from the light source passes through the polarizer of the reflective image display element and enters the liquid crystal element, where it is modulated for each pixel. Of the light emitted from the liquid crystal element, light having a predetermined polarization direction is transmitted through the analyzer and guided to the optical pupil via the axially asymmetric eyepiece optical system. Thereby, the observer can observe the virtual image of the image displayed on the image display element at the position of the optical pupil.

Here, when the liquid crystal element is a liquid crystal element having a ferroelectric liquid crystal, for example, the image is displayed black when the liquid crystal element does not act as a phase plate (reciprocating half-wave plate), but the axis of the eyepiece optical system In an asymmetric symmetry plane (hereinafter referred to as the YZ plane), the optical axis is tilted at an inclination angle other than perpendicular to the element plane of the liquid crystal element, so the direction perpendicular to the YZ plane from the center of the optical pupil The direction of the slow axis of the liquid crystal at the time of black display with respect to light from the liquid crystal element heading to a position shifted to the position (hereinafter referred to as the X direction) is the time of black display with respect to light from the liquid crystal element toward the center of the optical pupil. Slightly shifted (rotates) from the direction of the slow axis of the liquid crystal.

However, in the YZ plane, at least one of the relative angle between the polarizer surface and the element surface and the relative angle between the analyzer surface and the element surface is the normal between the optical axis and the element surface. Is set to be less than the relative angle of the optical pupil, so that the light from the liquid crystal element going to any position deviated in the X direction from the center of the optical pupil is shifted in the direction of the transmission axis of the polarizer or the direction of the transmission axis of the analyzer. Can be set equal to or less than the shift in the direction of the slow axis of the liquid crystal during black display. As a result, the angle difference between the slow axis of the liquid crystal during black display and the transmission axis of the polarizer during the black display, or the light from the liquid crystal element toward any position shifted in the X direction from the center of the optical pupil, or during black display. The angle difference between the slow axis of the liquid crystal and the transmission axis of the analyzer can be reduced. Therefore, regardless of the position of the observer's pupil in the X direction, it is possible to reliably absorb the image light during black display by the analyzer and observe a high-contrast image.

(A) is the explanatory view which developed the optical path in the YZ plane along the optical axis in the image display device of one embodiment of the present invention, and (b) developed the optical path in the ZX plane. It is explanatory drawing. It is a perspective view which shows the structure of the outline of HMD to which the said video display apparatus is applied. It is sectional drawing which shows the schematic structure of the said video display apparatus. It is explanatory drawing which shows typically the relationship between the advancing direction of the light on an optical axis, the advancing direction of the light of an X direction pupil end, and the direction of the slow axis of a liquid crystal. It is explanatory drawing which shows typically each direction of the transmission axis of a polarizer, the slow axis at the time of black display of a liquid crystal, and the transmission axis of an analyzer about the light on an optical axis. It is explanatory drawing which shows typically each direction of the transmission axis of a polarizer, the slow axis at the time of black display of a liquid crystal, and the transmission axis of an analyzer about the light of the X direction pupil end. (A) is an explanatory view in which the optical path of the video display device where α = θ and β = θ is developed in the YZ plane in the YZ plane, and (b) is the optical path of the video display device. It is explanatory drawing developed in the ZX plane. It is explanatory drawing which shows typically each direction of the transmission axis of a polarizer, the slow axis at the time of black display of a liquid crystal, and the transmission axis of an analyzer about the light of the X direction pupil end in the said video display apparatus. In the said video display apparatus, it is explanatory drawing which shows the polarization direction of the video light of the black display inject | emitted from a liquid crystal. It is explanatory drawing which shows typically each direction of the transmission axis of a polarizer, the slow axis at the time of white display of a liquid crystal, and the transmission axis of an analyzer about the light on an optical axis. It is explanatory drawing which shows typically each direction of the transmission axis of a polarizer, the slow axis at the time of white display of a liquid crystal, and the transmission axis of an analyzer about the light of a Y direction pupil end. (A) is explanatory drawing which expand | deployed the optical path in YZ plane of the video display apparatus set to (alpha) = + (theta) and (beta) = + (theta), (b) is an X direction pupil end in the said video display apparatus. It is explanatory drawing which shows typically each direction of the transmission axis of a polarizer, the slow axis at the time of black display of a liquid crystal, and the transmission axis of an analyzer about light. (A) is an explanatory diagram in which an optical path is developed in the YZ plane of the video display device in which α = + θ and β = −θ is set, and (b) is an X direction pupil end in the video display device. It is explanatory drawing which shows typically each direction of the transmission axis of a polarizer, the slow axis at the time of black display of a liquid crystal, and the transmission axis of an analyzer about this light. (A) is an explanatory diagram in which an optical path is developed in the YZ plane of the video display device in which α = −θ and β = + θ is set, and (b) is an X direction pupil end in the video display device. It is explanatory drawing which shows typically each direction of the transmission axis of a polarizer, the slow axis at the time of black display of a liquid crystal, and the transmission axis of an analyzer about this light. (A) is an explanatory diagram in which an optical path is developed in the YZ plane of the video display device in which α = −θ and β = −θ is set, and (b) is an X direction pupil in the video display device. It is explanatory drawing which shows typically each direction of the transmission axis of a polarizer, the slow axis at the time of black display of a liquid crystal, and the transmission axis of an analyzer about edge light. It is explanatory drawing which shows typically the other structure of the said video display apparatus. It is explanatory drawing which shows typically another structure of the said video display apparatus. It is explanatory drawing which shows typically another structure of the said video display apparatus. It is explanatory drawing which shows typically another structure of the said video display apparatus. It is explanatory drawing which shows typically another structure of the said video display apparatus. It is sectional drawing which shows the structure of the outline of the conventional video display apparatus.

An embodiment of the present invention will be described below with reference to the drawings.

(Configuration of HMD)
FIG. 2 is a perspective view showing a schematic configuration of the HMD according to the present embodiment. The HMD includes a video display device 1 and support means 2.

The video display device 1 has a housing 3. The casing 3 contains at least the light source 11 and the liquid crystal element 16 (both see FIG. 3) and holds a part of the eyepiece optical system 18. The eyepiece optical system 18 is configured by bonding an eyepiece prism 31 and a deflection prism 32, and has a shape like one lens of a pair of glasses (lens for right eye in FIG. 2) as a whole. The light source 11 and the liquid crystal element 16 are supplied with at least driving power and a video signal via a cable 4 provided through the housing 3.

The support means 2 supports the video display device 1 (particularly the eyepiece optical system 18) in front of one eye (for example, the right eye) of the observer and the dummy lens 5 to the other eye (for example, the left eye) of the observer. Support in front of. More details are as follows. Instead of providing the dummy lens 5, two video display devices 1 may be provided corresponding to both eyes and supported by the support means 2.

The support means 2 has a bridge 6, a frame 7, a temple 8, and a nose pad 9. The frame 7, the temple 8, and the nose pad 9 are provided as a pair on the left and right sides, and are each composed of a right frame 7R, a left frame 7L, a right temple 8R, a left temple 8L, a right nose pad 9R, and a left nose pad 9L. Yes.

One end of the bridge 6 is connected to the video display device 1, and the other end is connected to the dummy lens 5. The end of the video display device 1 opposite to the side connected to the bridge 6 is fixed to the right frame 7R. The right temple 8R is rotatably supported by the right frame 7R. On the other hand, the end of the dummy lens 5 opposite to the connection side with the bridge 6 is fixed to the left frame 7L. The left temple 8L is rotatably supported by the left frame 7L.

When the observer uses the HMD, the right temple 8R and the left temple 8L are brought into contact with the right and left heads of the observer, and the nose pad 9 is placed on the nose of the observer so as to wear general glasses. The HMD is attached to the observer's head. When an image is displayed on the image display device 1 in this state, the observer can observe the display image on the image display device 1 as a virtual image at the position of the optical pupil, and through the image display device 1. An external image can be observed with see-through. At this time, since the video display apparatus 1 is supported by the support means 2, the observer can observe the video provided from the video display apparatus 1 in a hands-free manner.

In the configuration in which the support unit 2 supports the two video display devices 1 corresponding to the eyes of the observer and performs binocular display, the eye width differs for each observer. It is necessary to make it easy to observe by setting it large. In this case, even if the pupil position differs from the center of the optical pupil for both the left eye and the right eye, according to the present invention, as described later, the relative relationship between at least one of the polarizer and the analyzer and the element surface of the liquid crystal element Since the angle is set appropriately, a high-contrast image can be observed regardless of the pupil position. That is, it is possible to observe a high-contrast image with both eyes without a difference in contrast between the left and right eyes. Details of the video display device 1 will be described below.

(Configuration of video display device)
FIG. 3 is a cross-sectional view illustrating a schematic configuration of the video display device 1. The video display apparatus 1 includes a light source 11, a polarizer 12, a mirror 13, a unidirectional diffuser plate 14, a polarizing plate 15, a liquid crystal element 16, an analyzer 17, and an axially asymmetric (rotationally asymmetric) eyepiece optical. System 18. The polarizer 12, the liquid crystal element 16, and the analyzer 17 constitute a reflective image display element (LCD) that modulates the light from the light source 11 and displays an image. This image display element is disposed on one end side (upper side in FIG. 3) of the eyepiece optical system 18 and is small and lightweight as a configuration in which image light is incident on the eyepiece optical system 18 from one end side. The display device 1 can be realized.

Here, for convenience of explanation below, directions are defined as follows. First, an optical axis is an axis that optically connects the center of the light source 11, the center of the element surface of the liquid crystal element 16, and the center of the optical pupil E formed by the eyepiece optical system 18. The element surface of the liquid crystal element 16 refers to a boundary surface between a liquid crystal sealing substrate 22 and a liquid crystal 23 described later. The optical axis direction when the optical path from the light source 11 to the optical pupil E is developed is taken as the Z direction. In addition, a direction perpendicular to an optical axis incident surface of a hologram optical element 33 (to be described later) of the eyepiece optical system 18 is defined as an X direction, and a direction perpendicular to the ZX plane is defined as a Y direction. The optical axis incident surface of the hologram optical element 33 refers to a plane including the optical axis of incident light and the optical axis of reflected light in the hologram optical element 33, that is, the YZ plane. Further, the eyepiece optical system 18 of the present embodiment has a symmetrical shape with respect to the plane including the optical axis, and the optical axis incident surface of the hologram optical element 33 is also a symmetrical plane of the eyepiece optical system 18. .

The light source 11 emits light toward the liquid crystal element 16 and is disposed on the observer side (optical pupil E side) with respect to the optical path of light traveling from the liquid crystal element 16 toward the eyepiece optical system 18. The light source 11 is composed of an RGB integrated light emitting diode (LED) that emits light corresponding to each color of R (red), G (green), and B (blue). The RGB light emitting units are arranged side by side in the X direction.

The light source 11 emits light in three wavelength bands of 465 ± 12 nm, 520 ± 19 nm, and 635 ± 10 nm, for example, with a center wavelength and a light intensity half-value wavelength width. The RGB light intensity of the light source 11 is adjusted in consideration of the diffraction efficiency of the hologram optical element 33 and the light transmittance of the liquid crystal element 16, thereby enabling white display. In the present embodiment, as will be described later, a ferroelectric liquid crystal element capable of time-division driving is used as the liquid crystal element 16, and therefore the light source 11 sequentially emits each light of RGB in time division.

The light source 11 may have one set or two sets of RGB light emitting units. When the light source 11 has two sets of RGB light emitting units, each group of light emitting units is arranged so that the light emitting units of the same color in each set are substantially symmetrical with respect to the YZ plane. At this time, the light emitting part having a longer wavelength of the emitted light is arranged at a position closer to the symmetry plane (YZ plane).

The polarizer 12 is a polarizing plate that transmits light in a predetermined polarization direction (for example, P-polarized light) out of the light from the light source 11 and guides it to the liquid crystal element 16. The polarizer 12 transmits polarized light (for example, P-polarized light) in the same direction as the polarizing plate 15 described later, and blocks (absorbs) polarized light (for example, S-polarized light) in the same direction as the analyzer 17 described later. But there is. Therefore, of the light emitted from the light source 11, the light that directly passes through the analyzer 17 (S-polarized light), or the light that is reflected by the surface of the polarizing plate 15 toward the analyzer 17 and passes therethrough. (S-polarized light) can be cut in advance by the polarizer 12, and unnecessary light that is not modulated by the liquid crystal element 16 can be prevented from being transmitted to the optical pupil E through the analyzer 17.

The mirror 13 is an illumination optical system that guides light from the light source 11 to an image display element (LCD). More specifically, the mirror 13 reflects light from the light source 11 and guides it to the liquid crystal element 16. The mirror 13 is an axially asymmetric optical system having a YZ plane as a symmetry plane, and is constituted by, for example, a cylindrical mirror having an optical power for collecting light only in the YZ plane. Thus, since the mirror 13 has optical power, the light from the light source 11 can be condensed and the liquid crystal element 16 can be illuminated, and a bright image can be observed by the observer. In addition, since the optical path of light from the light source 11 toward the liquid crystal element 16 is folded by the mirror 13, the apparatus can be reduced in size and weight. The mirror 13 may be composed of other mirrors such as an axially asymmetric aspherical mirror and an axially asymmetric concave mirror (free curved mirror).

Also, the mirror 13 is disposed outside the optical path from the liquid crystal element 16 toward the eyepiece optical system 18. More specifically, the mirror 13 is provided on the side opposite to the light source 11 with respect to the optical path of light from the liquid crystal element 16 toward the eyepiece optical system 18. As a result, only the analyzer 17 is disposed as an optical member in the optical path between the liquid crystal element 16 and the eyepiece optical system 18, and there is no irregularly reflecting optical element such as an illumination prism. It has become. Thereby, there is no flare light caused by unnecessary reflection on the inner surface of the prism, and a high-contrast and high-quality image can be observed.

The eyepiece optical system 18 described later is an optical system that is axially asymmetric with respect to the YZ plane, and the YZ plane is a symmetrical surface that is axially asymmetric. Therefore, the symmetry plane of the eyepiece optical system 18 and the symmetry plane of the mirror 13 (illumination optical system) are in the same plane.

The unidirectional diffusion plate 14 diffuses the light emitted from the light source 11 in the X direction perpendicular to the symmetry plane of the eyepiece optical system 18 and guides it to the liquid crystal element 16. More specifically, the unidirectional diffuser 14 diffuses incident light by 40 degrees in the X direction and 0.5 degrees in the Y direction. Instead of the unidirectional diffuser 14, a normal diffuser that diffuses incident light in both directions may be used.

The polarizing plate 15 transmits light of a predetermined polarization direction (for example, P-polarized light) transmitted through the polarizer 12 out of the light emitted from the light source 11 and guides it to the mirror 13 and reflects the light reflected by the mirror 13. (For example, P-polarized light) is transmitted and guided to the liquid crystal element 16. Even if the polarizing plate 15 generates a component that passes through the analyzer 17 due to diffusion by the unidirectional diffusion plate 14, it can be removed and a high-contrast image can be observed.

The analyzer 17 transmits light having a predetermined polarization direction out of the light emitted from the liquid crystal element 16 and guides it to the eyepiece optical system 18. The light having the predetermined polarization direction is light (for example, S-polarized light) having a polarization direction orthogonal to light transmitted through the polarizer 12 and the polarizing plate 15. Therefore, it can be said that the analyzer 17 is arranged so as to be crossed Nicol with the polarizer 12.

The liquid crystal element 16 is a reflective light modulation element that has a plurality of pixels in a matrix and modulates incident light (light from the light source 11) for each pixel according to image data. More specifically, the liquid crystal element 16 includes a silicon substrate 21 (first base material), a liquid crystal sealing base material 22 (second base material), and a liquid crystal 23. Has a counter electrode, an alignment film, and a control circuit (not shown).

Reflective electrodes are formed on the silicon substrate 21 corresponding to each pixel, wiring lines such as scanning lines and signal lines, and switching elements (for example, TFTs) for driving each pixel on / off are formed. ing. The liquid crystal sealing substrate 22 is made of, for example, a transparent cover glass, and is a substrate on which the above-described counter electrode is formed. The liquid crystal 23 is sandwiched between the silicon substrate 21 and the liquid crystal sealing base material 22 and modulates incident light by controlling the phase of polarized light. In the present embodiment, the liquid crystal 23 is composed of a ferroelectric liquid crystal.

In the case of black display, the liquid crystal 23 is controlled so that the major axis direction (slow axis direction) of the liquid crystal molecules is parallel or perpendicular to the P-polarized light, and the incident P-polarized light is emitted (reflected) as the P-polarized light. On the other hand, in the case of white display, it functions as a quarter wave plate (a half wave plate in a reciprocating manner), and converts incident P-polarized light into S-polarized light and emits (reflects) it.

The liquid crystal element 16 is arranged so that the long side direction of the rectangular display screen is the X direction and the short side direction is the Y direction. The liquid crystal element 16 does not have a color filter. Therefore, each pixel of the liquid crystal element 16 is ON / OFF driven in a time division manner corresponding to each of RGB light sequentially supplied from the light source 11 in a time division manner. Then, RGB display is performed in a time division manner with the same pixel. Thereby, a color image can be provided to the observer. Moreover, since the liquid crystal element 16 does not have a color filter, the light transmittance of the liquid crystal element 16 is high.

In the reflective liquid crystal element 16, a semiconductor such as silicon can be used as a substrate as described above, so that the liquid crystal element 16 having a small size and a high degree of integration can be manufactured. Moreover, since the peripheral circuit including the switching element and the wiring can be disposed on the back surface (the surface opposite to the display side) of the substrate, the aperture ratio can be easily improved and a bright image can be obtained. Can be displayed. Further, since the ferroelectric liquid crystal has a merit that the driving speed is high, therefore, the above time-division driving method can be employed. Further, since the high-contrast image can be displayed by using the ferroelectric liquid crystal as compared with the case of using the TN liquid crystal, the effect of the present invention described later can be observed regardless of the pupil position shift. It becomes effective.

The eyepiece optical system 18 is an optical system that guides image light emitted from the image display element (particularly the liquid crystal element 16) to the optical pupil E, and has positive optical power that is axisymmetric. The eyepiece optical system 18 includes an eyepiece prism 31, a deflection prism 32, and a hologram optical element 33.

The eyepiece prism 31 is a first transparent substrate that totally reflects incident light, that is, image light from the liquid crystal element 16 and guides it to the hologram optical element 33 while transmitting external light. For example, it is made of an acrylic resin. The eyepiece prism 31 is formed in a shape in which the lower end portion of the parallel plate is thinned into a wedge shape and the upper end portion is thickened. The eyepiece prism 31 is joined to the deflecting prism 32 with an adhesive so as to sandwich the hologram optical element 33 disposed at the lower end thereof.

The deflection prism 32 is configured by a substantially U-shaped parallel plate in plan view (see FIG. 2), and when attached to the lower end portion and both side surface portions (left and right end surfaces) of the eyepiece prism 31, the eyepiece prism. 31 is a second transparent substrate that is integrated with 31 to form a substantially parallel plate. By joining the deflecting prism 32 to the eyepiece prism 31, it is possible to prevent distortion in the external image that the observer observes through the eyepiece optical system 18.

That is, for example, when the deflecting prism 32 is not joined to the eyepiece prism 31, the light of the external field image is refracted when passing through the wedge-shaped lower end portion of the eyepiece prism 31, so that the external field image observed through the eyepiece prism 31 is changed. Distortion occurs. However, the deflection prism 32 is joined to the eyepiece prism 31 to form an integral substantially parallel plate, so that the deflection when the light of the external image passes through the wedge-shaped lower end of the eyepiece prism 31 is canceled by the deflection prism 32. can do. As a result, it is possible to prevent distortion in the external image observed through the see-through.

The hologram optical element 33 is a volume phase type reflection hologram that diffracts RGB image light emitted from the liquid crystal element 16 and guides it to the optical pupil E. The hologram optical element 33 has optically asymmetric positive power and has the same function as an aspherical concave mirror. Thereby, the degree of freedom of arrangement of each optical member constituting the apparatus can be increased, and the apparatus can be easily reduced in size, and an image with good aberration correction can be provided to the observer.

The hologram optical element 33 has, for example, three wavelength ranges of 465 ± 5 nm (B light), 521 ± 5 nm (G light), and 634 ± 5 nm (R light) with a peak wavelength of diffraction efficiency and a wavelength width of half value of diffraction efficiency. It is made to diffract (reflect) light. Here, the peak wavelength of diffraction efficiency is the wavelength at which the diffraction efficiency reaches a peak, and the wavelength width at half maximum of the diffraction efficiency is the wavelength width at which the diffraction efficiency is at half maximum of the diffraction efficiency peak. It is.

Since the hologram optical element 33 is fabricated so as to diffract only light having a specific wavelength at a specific incident angle, it hardly affects the transmission of external light. Therefore, the observer can see the external image as usual through the eyepiece prism 31, the hologram optical element 33, and the deflection prism 32.

Furthermore, from the above-mentioned numerical relationship, it can be said that the peak wavelength of the diffraction efficiency of the hologram optical element 33 and the peak wavelength (center wavelength) of the light intensity emitted from the light source 11 are substantially the same. In such a setting, the light in the vicinity of the wavelength at which the light intensity reaches a peak among the light emitted from the light source 11 is efficiently diffracted by the hologram optical element 33, so that it is bright even when superimposed on the external image, An easy-to-view video can be provided to the observer. Further, the positions of the optical pupils of the respective colors coincide with each other in the Y direction, and the entire optical pupil E can be reduced.

(Operation of video display device)
Next, the operation of the video display device 1 having the above configuration will be described.

Each color light of RGB (for example, P-polarized light) emitted from the light source 11 in a time division manner is first transmitted through the polarizer 12, enters the mirror 13 through the polarizing plate 15 and the one-way diffusion plate 14, and is reflected there. . Then, the reflected light (P-polarized light) from the mirror 13 enters the unidirectional diffuser plate 14 again, is diffused in the X direction, passes through the polarizing plate 15 and enters the liquid crystal element 16.

In the liquid crystal element 16, incident light is reflected, and at that time, phase modulation is performed for each pixel in accordance with image data for each RGB. For example, in a pixel corresponding to black display, incident light is not phase-modulated, is emitted from the liquid crystal element 16 as P-polarized light, and is absorbed by the analyzer 17. On the other hand, in the pixel corresponding to white display, the liquid crystal element 16 acts as a quarter wavelength plate (reciprocating half wavelength plate), and incident light is converted into S-polarized light and transmitted through the analyzer 17. By controlling the modulation time in the liquid crystal element 16 or the intensity of light emitted from the light source 11, a color image can be displayed on the LCD. Note that it is arbitrary which one of P-polarized light and S-polarized light is used for white display.

The image light transmitted through the analyzer 17 is incident on the eyepiece prism 31 of the eyepiece optical system 18 through a surface 31a having a convex curved surface. The incident image light is totally reflected a plurality of times by two opposing planes (

surfaces

31 b and 31 c) of the eyepiece prism 31, guided to the hologram optical element 33 disposed at the lower end of the eyepiece prism 31, reflected there, and optically received. Guided to pupil E. Therefore, at the position of the optical pupil E, the observer can observe an enlarged virtual image of each RGB image displayed on the LCD as a color image.

On the other hand, the eyepiece prism 31, the deflecting prism 32, and the hologram optical element 33 transmit almost all the external light, so that the observer can observe the external image in a see-through manner. Therefore, the virtual image of the image displayed on the LCD is observed while overlapping a part of the external image.

In the present embodiment, the analyzer 17 is arranged so as to be crossed Nicol with the polarizer 12, and in black display, the liquid crystal element 16 maintains the polarization direction of the light (P-polarized light) transmitted through the polarizer 12. The analyzer 17 absorbs the light in the polarization direction. In this way, at the time of black display, the liquid crystal element 16 does not convert the light transmitted through the polarizer 12, so that the light transmitted through the polarizer 12 and incident on the liquid crystal element 16 and emitted therefrom (black display The image light) is reliably absorbed by the analyzer 17, and a high-contrast image can be observed. Therefore, in the configuration in which the liquid crystal element 16 performs black display without rotating the polarization, the configuration of the present invention described later, that is, the configuration for observing a high-contrast image regardless of the pupil position in the X direction (polarizer). 12, the inclined arrangement of the liquid crystal element 16 and the analyzer 17 with respect to the optical axis) is very effective.

At this time, it is desirable that the transmission axis of the polarizer 12 is parallel or perpendicular to the axially asymmetric symmetry plane (YZ plane) of the eyepiece optical system 18. In this configuration, since the direction of the transmission axis of the polarizer 12 does not have both a component parallel to the YZ plane and a component perpendicular to the YZ plane, the polarizer 12 or the analyzer 17 has a predetermined value in the YZ plane as described later. Even when tilted at each tilt angle, the transmission axis of the polarizer 12 and the absorption axis of the analyzer 17 (axis perpendicular to the transmission axis) can be maintained parallel to the YZ plane. This makes it possible for the analyzer 17 to reliably absorb the light transmitted through the polarizer 12 during black display and observe a high-contrast image.

In the image display device 1 of the present embodiment, the hologram optical element 33 of the eyepiece optical system 18 is used as a combiner that simultaneously guides the image light from the LCD and external light to the observer's pupil. Can simultaneously observe an image provided from the LCD and an external image via the hologram optical element 33.

Further, since the hologram optical element 33 has higher diffraction efficiency of S-polarized light than P-polarized light, the image light emitted from the liquid crystal element 16 and transmitted through the analyzer 17 is changed to S-polarized light as in the present embodiment. Bright images with high color purity can be observed by an observer. A configuration in which P-polarized light is emitted from the liquid crystal element 16 and after passing through the analyzer 17 may be converted to S-polarized light by a half-wave plate.

Further, since the deflection prism 32 cancels the refraction of the external light at the wedge portion of the eyepiece prism 31, the observer observes the external light through the eyepiece prism 31, the deflection prism 32, and the hologram optical element 33 without distortion. Can do. In addition, since the image light is reflected in the eyepiece prism 31 and guided to the eye, the eyepiece prism 31 can be made thin (for example, about 3 mm) as much as a normal eyeglass lens, and the size and weight can be reduced. Become. In addition, since the reflection in the eyepiece prism 31 is set as total reflection, the observer can observe an external image through the

surfaces

31b and 31c of the eyepiece prism 31 without reducing the transmittance of outside light.

Further, since the image display device 1 is an axially asymmetric optical system, the principal ray of image light (the ray on the optical axis) used in the eyepiece optical system 18 is YZ plane with respect to the display surface of the liquid crystal element 16. It is inclined in the Y direction. Since the ferroelectric liquid crystal element 16 displays black when it does not act as a phase plate, the liquid crystal molecules coincide with the polarization direction in the YZ plane, and the polarization is not changed. Therefore, even when obliquely incident on the liquid crystal element 16, there is little leakage light for black display, and display with high contrast is possible. On the other hand, when white is displayed, the liquid crystal element 16 acts as a quarter wavelength plate (reciprocating half wavelength plate), so that the intensity of light passing through the analyzer 17 varies depending on the wavelength (wavelength dependence). However, this wavelength dependence can be canceled by adjusting the intensity of light emitted from the light source 11 or adjusting the modulation time in the liquid crystal element 16.

In this embodiment, the positional relationship between the light source 11 and the optical pupil E is almost conjugate (see FIG. 3). Here, since the reflective liquid crystal element 16 has a high aperture ratio, the diffusion of each pixel of the liquid crystal element 16 is small. Therefore, it can be said that the light source 11 and the optical pupil E are optically conjugate in the Y direction. On the other hand, in the X direction, since there is no optical power of the mirror 13, the light source 11 and the optical pupil E are not optically conjugate. The mirror 13 is arranged so that the light diffused by the one-way diffuser plate 14 after the light from the light source 11 is condensed forms the optical pupil E efficiently. It is possible to observe bright images.

Further, in this embodiment, the optical arrangement and optical power of each optical member are set so that the optical pupil E has a half intensity value of 6 mm in the X direction and 2 mm in the Y direction. In the Y direction, the light emitting area (for example, 0.3 mm square) of the light source 11 is conjugated with 0.5 degree diffusion in the unidirectional diffusion plate 14 and about 2 degree diffusion in the liquid crystal element 16. It is formed to be slightly larger than the pupil formed at the image magnification.

Thus, since the optical pupil E is 6 mm larger than the human pupil (about 3 mm) in one direction (X direction), the observer can easily observe the image. On the other hand, since the optical pupil E has a size of 2 mm which is smaller than the human pupil in the other direction (Y direction), the light from the light source 11 is condensed on the optical pupil E in the above direction without waste. Thereby, the observer can observe a bright image. In other words, when an observer observes an image, if the X direction is set to the left and right direction of the observer and the Y direction is set to the up and down direction, the observer moves well and has a large pupil in the left and right direction with a wide observation range. This makes it easy to observe the image, and it is possible to observe a bright image by focusing on a small pupil in the vertical direction.

(About the effect of reducing color unevenness by setting the optical pupil)
In the present embodiment, as described above, the optical pupil E is set to have a half intensity value of 6 mm in the X direction and 2 mm in the Y direction. That is, the optical pupil E is larger in the X direction, that is, the direction perpendicular to the optical axis incident surface, than in the Y direction, that is, the direction parallel to the optical axis incident surface (YZ plane) of the hologram optical element 33. By setting the size of the optical pupil E in this way, the observer can observe a high-quality image with little color unevenness without being greatly affected by the wavelength characteristic (wavelength selectivity) of the hologram optical element 33. Can do. The reason is as follows.

First, the relationship between the incident angle and the wavelength selectivity in the hologram optical element 33 will be described. In the hologram optical element 33 having interference fringes that diffract light having an incident angle greater than 0 degrees, the wavelength selectivity is smaller in the direction perpendicular to the optical axis incident surface than in the direction parallel to the optical axis incident surface (incident angle). The diffraction wavelength shift due to the shift is small. In other words, the angle selectivity with respect to the shift of the incident angle to the interference fringes is lower in the direction perpendicular to the optical axis incident surface than in the direction parallel to the optical axis incident surface. This is because when the light is incident on the interference fringes of the hologram optical element 33 with an incident angle, the angle deviation of the incident angle in the optical axis incident surface is directly the angle deviation of the incident angle. Although the influence is large, the angle deviation in the direction perpendicular to the optical axis incident surface is small as the deviation of the incident angle, and the influence on the diffraction wavelength is small.

Therefore, when light having an angle deviated from a predetermined incident angle is incident on the interference fringes of the hologram optical element 33, the angle deviation in the Y direction parallel to the optical axis incident surface is more likely to occur on the optical axis incident surface even with the same angle deviation. The diffraction wavelength is greatly shifted from the angle deviation in the vertical X direction (that is, the Y direction parallel to the optical axis incident surface has a large wavelength selectivity).

Therefore, by forming the optical pupil E small in the Y direction where the change in the diffraction wavelength is large, the range of change in the diffraction wavelength is narrowed, so that the color unevenness on the optical pupil E can be reduced. Further, even if the optical pupil E is formed large in the X direction perpendicular to the optical axis incident surface, an image with high color purity can be provided to the observer. In addition, although the incident surface of the light outside the optical axis incident surface is not slightly parallel to the optical axis incident surface, as described above, the angle shift in the direction perpendicular to the optical axis incident surface has little influence on the diffraction wavelength. Even if the incident surface is used as a reference, color unevenness does not increase.

(About the positional relationship of polarizer, liquid crystal element, analyzer)
Next, the positional relationship between the polarizer 12, the liquid crystal element 16, and the analyzer 17 will be described.

FIG. 1A is an explanatory diagram in which the optical path from the light source 11 to the optical pupil E along the optical axis AX is developed in the YZ plane in the video display device 1 described above, and FIG. It is explanatory drawing which expand | deployed the optical path in ZX plane. 1 (a) indicates light from the liquid crystal element 16 (hereinafter referred to as Y-direction pupil end light) that is directed to a position shifted in the Y direction from the center of the optical pupil E (for example, an end portion in the Y direction). ). In addition, a two-dot chain line in FIG. 1B indicates light from the liquid crystal element 16 (hereinafter referred to as light at the X-direction pupil end) toward a position shifted in the X direction from the center of the optical pupil E (for example, the X direction end). Designated). As described above, the optical pupil E is set larger in the X direction than in the Y direction.

As shown in FIGS. 1A and 1B, the eyepiece optical system 18 is an axisymmetric optical system in the YZ plane and an axially symmetric optical system in the ZX plane. In the YZ plane (in the symmetry plane) in which the eyepiece optical system 18 is axially asymmetric, the optical axis AX is inclined at an inclination angle other than perpendicular to the element surface of the liquid crystal element 16.

Here, a ray on the optical axis AX is a principal ray, and an incident angle of the principal ray on the liquid crystal element 16 in the YZ plane is θ (°). That is, θ is an angle formed by the normal line of the element surface of the liquid crystal element 16 in the YZ plane and the optical axis AX. Since the optical system is set to be substantially telecentric in order to reduce the optical aberration, the liquid crystal element 16 also has an incident angle close to the angle θ in the YZ plane with respect to the incident light other than the center of the element surface. Is incident on. In the present embodiment, θ ≧ 10 ° is set in order to reduce the size of the apparatus while ensuring optical performance (for example, performance related to aberration) while increasing the degree of freedom of arrangement of the optical members.

In the YZ plane, which is the symmetry plane of the axially asymmetric system, the relative angle between the plane of the polarizer 12 and the element plane of the liquid crystal element 16 is α (°), and the plane of the analyzer 17 and the element of the liquid crystal element 16 Let the relative angle to the surface be β (°). Hereinafter, α and β are also referred to as the inclination angle of the polarizer 12 and the inclination angle of the analyzer 17, respectively.

In the present embodiment, the polarizer 12, the liquid crystal element 16, and the analyzer 17 are arranged so that α <θ and β <θ in the YZ plane when the optical path is developed along the optical axis AX. Has been. Thus, regardless of the position of the observer's pupil in the X direction, it is possible to reliably absorb the image light during black display by the analyzer 17 and observe a high-contrast image. The reason is as follows.

4, the traveling direction X ₀ of the light on the optical axis AX, and the traveling direction X ₁ of the light in the X direction the pupil edge, the relationship between the direction D ₀ of the slow axis of the liquid crystal molecules of the liquid crystal 23 schematically It is explanatory drawing shown. FIG. 5 is an explanatory diagram schematically showing the directions of the transmission axis of the polarizer 12, the slow axis during black display of the liquid crystal 23, and the transmission axis of the analyzer 17 for light on the optical axis AX. is there. For light on the optical axis AX, the direction of the transmission axis of the polarizer 12 and the direction of the slow axis during black display of the liquid crystal 23 are set to the Y direction, and the direction of the transmission axis of the analyzer 17 is X Set to direction.

The normal of the element surface of the liquid crystal element 16 is inclined by an angle θ with respect to the optical axis AX in the YZ plane, and the slow axis of the liquid crystal 23 during black display is inclined in the YZ plane. Here, the polarizer 12 and the analyzer 17 are inclined at an inclination angle α and an inclination angle β, respectively, in a plane parallel to a plane including the slow axis and the optical axis when the liquid crystal 23 displays black. For the light on the optical axis AX, the direction of the transmission axis of the polarizer 12, the direction of the slow axis when the liquid crystal 23 displays black, and the direction of the transmission axis of the analyzer 17 are in the traveling direction of the light. The light that has passed through the polarizer 12 without being tilted in a vertical plane is reliably absorbed by the analyzer 17 and has high contrast. As shown in FIG. 4, for example, the slow axis direction D ₀ when the liquid crystal 23 displays black is the Y direction when viewed from the X ₀ direction in which the light on the optical axis AX travels. In the XY plane perpendicular to the axis AX, it can be easily understood because it does not tilt from the Y direction. Similarly, the transmission axis of the polarizer 12 and the transmission axis of the analyzer 17 are not inclined in the plane. Further, not only for light on the optical axis AX but also for light at the Y-direction pupil end indicated by a one-dot chain line in FIG. 1A, for example, the direction of the transmission axis of the polarizer 12 and the liquid crystal 23 during black display. Since the slow axis direction and the transmission axis direction of the analyzer 17 are not inclined in a plane perpendicular to the light traveling direction, the contrast is high.

On the other hand, FIG. 6 shows the transmission axis of the polarizer 12, the slow axis during black display of the liquid crystal 23, and the transmission axis of the analyzer 17 for the light at the X-direction pupil end indicated by the two-dot chain line in FIG. It is explanatory drawing which shows each direction of these typically. Since the slow axis when the liquid crystal 23 displays black is tilted in the YZ plane, the light at the X direction pupil end, as shown in FIG. 4, is the direction D ₀ of the slow axis when the liquid crystal 23 displays black. is inclined when viewed from the direction of X ₁ where the light in the X direction pupil edge proceeds, for example, the direction of D ₁ in the optical axis perpendicular to the projection plane in AX. For this reason, with respect to the light at the X direction pupil end, as shown in FIG. 6, the slow axis at the time of black display of the liquid crystal 23 is slightly shifted from the Y direction by an angle B within a plane perpendicular to the light traveling direction. Similarly, since the polarizer 12 and the analyzer 17 are inclined in the YZ plane so that α <θ and β <θ (see FIG. 1A), the light at the X-direction pupil end is determined. The transmission axis of the polarizer 12 is slightly shifted from the Y direction by an angle A in a plane perpendicular to the traveling direction, and the transmission axis of the analyzer 17 is an angle C from the X direction in a plane perpendicular to the traveling direction. A little off.

During black display, it is ideal that the analyzer 17 absorbs all the light from the polarizer 12 and does not leak light, but the slow axis of the liquid crystal 23 acting as a half-wave plate, the polarizer 12 and When the transmission axes of the analyzer 17 are deviated from parallel or perpendicular, the larger the deviation angle, the more light is transmitted through the analyzer 17, and the amount thereof is determined by the polarization direction of the light incident on the analyzer 17 and the analyzer 17. Is proportional to the square of the sine of the angle of deviation from the direction of the transmission axis. Therefore, in the example of FIG. 6, out of the light transmitted through the polarizer 12,
{Sin (2B-AC)} ²
That is, the light corresponding to this ratio passes through the analyzer 17.

However, in this embodiment, by setting the inclination angle α of the polarizer 12 and the inclination angle β of the analyzer 17 to be less than θ, the direction of the transmission axis of the polarizer 12 with respect to the light at the X direction pupil end or The direction of the transmission axis of the analyzer 17 can be shifted by a shift amount equal to or less than the shift of the slow axis direction of the liquid crystal 23 during black display. As a result, the shift amount (| BA | or | BC |) becomes small. In addition, since the slow axis of the liquid crystal 23 during black display and the transmission axes of the polarizer 12 and the analyzer 17 are shifted in the same direction, the component transmitted through the analyzer 17 in the light from the polarizer 12 is very Becomes smaller. This is true not only for the light at the X-direction pupil end, but also for the light going to any position shifted in the X direction from the center of the optical pupil E. Therefore, regardless of the position of the observer's pupil in the X direction, the image light during black display can be reliably absorbed by the analyzer 17 and a high contrast image can be observed.

For example, when the focal length of the eyepiece optical system 18 is 20 mm and the size of the optical pupil E in the X direction is 5 mm, ZX of light rays emitted from the center of the element surface of the liquid crystal element 16 toward the pupil end in the X direction The angle formed with the optical axis AX in the plane is about 14 °. At this time, if θ = 15 °, α = 3 °, and β = 1 °, the angle A is about 3 °, the angle B is about 3.8 °, and the angle C is about 4.1 °. Therefore, from the above equation, light leaks by 0.00008 at a rate when the incident light is 1. For example, when the ratio of white to black is 100: 1 on the optical axis, the contrast is 100: 1.008 at the pupil edge in the X direction, and the same high contrast as that on the optical axis can be achieved. It should be noted that a high-contrast image can be observed at the X-direction pupil end even when the contrast is higher, such as 1000: 1 on the optical axis, or when the contrast is lower than 100: 1 on the optical axis.

In the above, the case where α <θ and β <θ in the YZ plane has been described. However, as long as at least one of α <θ and β <θ is satisfied, regardless of the pupil position in the X direction. The effect of the present invention that enables observation of a high-contrast image can be obtained. An example that satisfies one of α <θ and β <θ will be described later. In particular, as in this embodiment, by satisfying both α <θ and β <θ, the effect can be reliably obtained. Can do.

(Contrast when α = θ and β = θ)
Next, the contrast at the X-direction pupil end when α and β are the upper limit θ in the YZ plane will be described. FIG. 7A is an explanatory diagram in which the optical path of the video display apparatus 1 in which α = θ and β = θ is developed in the YZ plane along the optical axis AX in the YZ plane. b) is an explanatory diagram in which the optical path of the video display device 1 is developed in the ZX plane along the optical axis AX.

In the YZ plane, when α = θ and β = θ, the polarizer 12 and the analyzer 17 are arranged to be perpendicular to the optical axis AX and are parallel to each other. However, here, when the optical path is developed in the YZ plane, the polarizer 12 and the analyzer 17 are inclined by + θ in the same direction as the normal of the element surface of the liquid crystal element 16 approaches the optical axis AX. Shall.

Regarding the light on the optical axis AX, the respective directions of the transmission axis of the polarizer 12, the slow axis during black display of the liquid crystal 23, and the transmission axis of the analyzer 17 are the same as in FIG. That is, the polarizer 12 and the analyzer 17 have an inclination angle α (= θ) and an inclination angle β (= θ) in a plane parallel to a plane including the slow axis and the optical axis when the liquid crystal 23 displays black. Since each is inclined, for the light on the optical axis AX, the direction of the transmission axis of the polarizer 12, the direction of the slow axis when the liquid crystal 23 displays black, and the direction of the transmission axis of the analyzer 17 are: The light that has passed through the polarizer 12 without being inclined in the plane perpendicular to the traveling direction of the light is reliably absorbed by the analyzer 17 and has a high contrast. Further, not only the light on the optical axis AX but also the light at the pupil edge in the Y direction indicated by the one-dot chain line in FIG.

On the other hand, FIG. 8 shows the transmission axis of the polarizer 12, the slow axis during black display of the liquid crystal 23, and the transmission axis of the analyzer 17 for the light at the pupil edge in the X direction indicated by the two-dot chain line in FIG. It is explanatory drawing which shows each direction of these typically. As for the light at the X-direction pupil end, the slow axis during black display of the liquid crystal 23 is shifted from the Y direction by an angle D (°), as in FIG. However, as shown in FIG. 7A, the polarizer 12 and the analyzer 17 are substantially perpendicular to the optical axis AX, so that each transmission axis hardly deviates from the Y direction and the X direction. Therefore, as shown in FIG. 9, the polarization direction of the light transmitted through the polarizer 12 is rotated by an angle 2D that is twice the deviation of the slow axis of the liquid crystal 23 from the Y direction (the liquid crystal 23 has a half wavelength). It doubles to act as a plate). As a result, of the light transmitted through the polarizer 12,
{Sin (2D)} ²
The light corresponding to this ratio (component P parallel to the transmission axis of the analyzer 17) is transmitted through the analyzer 17.

Here, when the contrast at the X-direction pupil end is calculated by setting the focal length of the eyepiece optical system 18 to the same conditions as described above, an angle deviation of twice the angle D = 3.8 ° affects the leakage light. The amount of the leaked light is 0.017 in a ratio where the incident light is 1. Therefore, when the contrast is 100 to 1 on the optical axis, the contrast is 100 to 2.7 at the pupil edge in the X direction. In other words, according to the present invention, when the contrast is 100 to 1 on the optical axis, the contrast is at least 100 to 2.7 at the pupil edge in the X direction.

10 and 11 show the transmission axis of the polarizer 12 and the slow axis during white display of the liquid crystal 23 in the configurations of FIGS. 1 (a) and 1 (b) and FIGS. 7 (a) and 7 (b). FIG. 10 is a diagram schematically illustrating each direction of the transmission axis of the analyzer 17. FIG. 10 shows the light on the optical axis, and FIG. 11 shows the Y-direction pupil end. In the case of white display, as shown in FIG. 10, the direction of the slow axis of the liquid crystal 23 also deviates from 45 degrees with respect to the light on the optical axis, and the analyzer 17 transmits the polarization direction of the light transmitted through the polarizer 12. Cannot rotate reliably in the direction of However, the contrast hardly changes even if the brightness of white becomes somewhat dark. For example, when the white level is set to 100 for a display with a contrast of 100 to 1, even if white is decreased by 2, it is only 98 to 1 and still has a high contrast. Further, as shown in FIG. 11, for the light at the Y-direction pupil end, the slow axis of the liquid crystal 23 further shifts from 45 degrees during white display, but it can be said that the influence on the contrast is small as described above.

(Relationship between tilt direction of polarizer and analyzer and contrast)
Next, a simulation result of the relationship between the tilt direction of the polarizer 12 and the analyzer 17 in the YZ plane and the contrast will be described. If the deviation angle (relative angle) between the polarization direction of the light incident on the analyzer 17 and the transmission axis of the analyzer 17 is δ, δ = 2B−A−C, where B = Δθ (° ). Further, the positive and negative values of α and β are the inclination directions of the polarizer 12 and the analyzer 17 in the same direction as the normal of the element surface of the liquid crystal element 16 approaches the optical axis AX when the optical path is developed in the YZ plane. Let (rotation direction) be positive (for example, + θ).
(1) When α = + θ and β = + θ FIG. 12A is an explanatory diagram in which the optical path is developed in the YZ plane of the video display device 1 in which α and β are set as described above. 12 (b) shows the respective directions of the transmission axis of the polarizer 12, the slow axis during black display of the liquid crystal 23, and the transmission axis of the analyzer 17 for the light at the pupil in the X direction in the video display device 1. It is explanatory drawing shown typically. In the YZ plane, when α = + θ and β = + θ, that is, as described above, when the polarizer 12 and the analyzer 17 are arranged so as to be perpendicular to the optical axis AX and are parallel to each other, During black display, A = 0 °, B = Δθ, C = 0 °, and δ = 2Δθ from the above equation. Accordingly, for the light at the X-direction pupil end, the black display image light leaks slightly from the analyzer 17 and becomes lower in contrast than the cases (2) and (3) described later, but this contrast is ensured at the minimum. be able to.
(2) When α = + θ and β = −θ FIG. 13A is an explanatory diagram in which the optical path is developed in the YZ plane of the video display apparatus 1 in which α and β are set as described above. FIG. 13B shows each direction of the transmission axis of the polarizer 12, the slow axis during black display of the liquid crystal 23, and the transmission axis of the analyzer 17 for the light at the X-direction pupil end in the video display device 1. It is explanatory drawing which shows this typically. In the YZ plane, when α = + θ and β = −θ, that is, the polarizer 12 and the analyzer 17 are not parallel to each other (the polarizer 12 and the analyzer 17 are inclined in opposite directions), When the relative angle α between the surface of the polarizer 12 and the element surface of the liquid crystal element 16 is equal to the relative angle β between the surface of the analyzer 17 and the element surface of the liquid crystal element 16, A = 0 ° during black display, B = Δθ, C = 2Δθ, and δ = 0 ° from the above equation. Therefore, under this condition, it is possible to reliably eliminate the leakage light from the analyzer 17 with respect to the light at the X-direction pupil end, and to reliably realize high contrast.
(3) When α = −θ and β = + θ FIG. 14A is an explanatory diagram in which the optical path is developed in the YZ plane of the video display device 1 in which α and β are set as described above. FIG. 14B shows each direction of the transmission axis of the polarizer 12, the slow axis during black display of the liquid crystal 23, and the transmission axis of the analyzer 17 for the light at the X direction pupil end in the video display device 1. It is explanatory drawing which shows this typically. In the YZ plane, when α = −θ and β = + θ, that is, the polarizer 12 and the analyzer 17 are not parallel to each other (the polarizer 12 and the analyzer 17 are inclined in opposite directions), When the relative angle α between the surface of the polarizer 12 and the element surface of the liquid crystal element 16 is equal to the relative angle β between the surface of the analyzer 17 and the element surface of the liquid crystal element 16, A = 2Δθ, B = Δθ, C = 0 °, and from the above equation, δ = 0 °. Therefore, even under this condition, the leakage light from the analyzer 17 can be surely eliminated for the light at the X-direction pupil end, and high contrast can be reliably realized.
(4) When α = −θ and β = −θ FIG. 15A is an explanatory diagram in which the optical path is developed in the YZ plane of the video display device 1 in which α and β are set as described above. FIG. 15B shows the transmission axis of the polarizer 12, the slow axis during black display of the liquid crystal 23, and the transmission axis of the analyzer 17 for the light at the pupil in the X direction in the video display device 1. It is explanatory drawing which shows a direction typically. When α = −θ and β = −θ in the YZ plane, that is, when the polarizer 12 and the analyzer 17 are not perpendicular to the optical axis AX and are parallel to each other, A = 2Δθ, B = Δθ, C = 2Δθ, and from the above equation, δ = -2Δθ. Therefore, for the light at the pupil edge in the X direction, the image light for black display leaks slightly from the analyzer 17 and the contrast becomes lower than in the cases (2) and (3) above, but in the case of (1) above. Similarly, this contrast can be secured at least.

Note that, as in the above (2) and (3), the polarizer 12 and the analyzer 17 are not parallel to each other, and the relative angle α between the surface of the polarizer 12 and the element surface of the liquid crystal element 16 is the analyzer. The configuration equal to the relative angle β between the surface 17 and the element surface of the liquid crystal element 16 is effective even when the condition of α <θ or β <θ is not satisfied in the YZ plane (at least one of α and β is θ In this case, a high-contrast image can be observed regardless of the position in the X direction.

That is, the embodiments of (2) and (3) described above are as follows: “When the optical path is developed along the optical axis, the plane of the polarizer and the element plane of the liquid crystal element are within the axially asymmetric symmetry plane of the eyepiece optical system. And at least one of the relative angle between the analyzer surface and the element surface is less than the relative angle between the optical axis and the normal of the element surface. Can be realized.

(Other configuration of video display device)
FIG. 16 is an explanatory view schematically showing another configuration of the video display device 1 of the present embodiment. In the figure, the illustration of the configuration after the eyepiece optical system 18 is omitted. In the video display device 1, when the optical path is developed along the optical axis AX in the YZ plane, the surface of the analyzer 17 and the element surface of the liquid crystal element 16 are optically parallel, that is, β The analyzer 17 is arranged so that = 0 °, and the relative angle between the surface of the polarizer 12 and the element surface of the liquid crystal element 16 is larger than the angle formed between the normal of the element surface and the optical axis AX. The polarizer 12 is arranged so as to increase, that is, α> θ. Therefore, the polarizer 12 and the analyzer 17 are optically inclined. The polarizer 12 is arranged on the opposite side of the light source 11 with respect to the optical path from the liquid crystal element 16 toward the analyzer 17, that is, in the optical path between the mirror 13 and the liquid crystal element 16.

In the configuration of FIG. 16, β (= 0 °) <θ and one of α <θ and β <θ is satisfied. Therefore, as described above, high contrast is achieved regardless of the pupil position in the X direction. The video can be observed. However, in this configuration, since α> θ, the contrast at the X-direction pupil end is slightly reduced as compared with the configuration satisfying both α <θ and β <θ, but still high contrast can be realized. it can.

For example, when the focal length of the eyepiece optical system 18 is 20 mm and the size of the optical pupil E in the X direction is 5 mm, ZX of light rays emitted from the center of the element surface of the liquid crystal element 16 toward the pupil end in the X direction The angle formed with the optical axis AX in the plane is about 14 °. At this time, when θ = 15 °, α = 45 °, and β = 1 °, when the angle formed by the normal of the surface of the polarizer 12 and the optical axis AX is 45 °, the angle A is about 8. 2 °, the angle B is about 3.8 °, and the angle C is about 4.1 °. Therefore, from the above equation, light leaks by 0.007 at a rate when the incident light is 1. For example, when the ratio of white to black is 100: 1 on the optical axis, the contrast is 100: 1 to 1.7 at the pupil edge in the X direction, but the contrast is still high. The same can be said for α <θ and β> θ. Therefore, even if only one of α <θ and β <θ is satisfied, it can be said that an image with relatively high contrast can be observed regardless of the pupil position in the X direction.

Incidentally, FIG. 17 is an explanatory view schematically showing still another configuration of the video display device 1. In the figure, the illustration of the configuration after the eyepiece optical system 18 is omitted. As shown in the figure, the polarizer 12 may be formed in a cylindrical shape along the mirror 13, that is, a shape having a curvature only in the YZ plane. In this case, the polarizer 12 can be easily attached to the curved mirror 13 and can be held integrally.

For the light on the optical axis AX, the slow axis of the liquid crystal 23 during black display and the transmission axis of the polarizer 12 do not deviate from the Y direction in the respective planes. Contrast does not decrease even if it is bent in the plane. That is, since the polarizer 12 has a cylindrical shape, it is inevitable that the contrast slightly differs depending on the screen and the pupil position, but the plane of the analyzer 17 is parallel to the element plane of the liquid crystal element 16 (β = 0 °). Thus, similarly to the configuration of FIG. 16, an image with high contrast can be observed regardless of the pupil position in the X direction. The case where the analyzer 17 is bent in the YZ plane can be considered in the same manner as described above, and even in this case, an image with high contrast can be observed.

FIG. 18 is an explanatory diagram schematically showing still another configuration of the video display device 1. In the figure, the illustration of the configuration after the eyepiece optical system 18 is omitted. In this video display device 1, an illumination prism 41 is arranged instead of the mirror 13, and α is set to approximately β = 0 °.

The illumination prism 41 has a concave reflecting surface 41a, and the optical path of light from the polarizer 12 toward the liquid crystal element 16 is bent by the concave reflecting surface 41a. That is, the light from the light source 11 that has passed through the polarizer 12 enters the illumination prism 41, is reflected by the concave reflecting surface 41 a, and enters the liquid crystal element 16. Then, the light emitted from the liquid crystal element 16 enters the illumination prism 41 again, passes therethrough, and travels toward the analyzer 17.

According to this configuration, since both the surface of the polarizer 12 and the surface of the analyzer 17 are optically parallel to the element surface of the liquid crystal element 16, one of the surface of the polarizer 12 and the surface of the analyzer 17. Compared with the case where only the optical element is optically parallel to the element surface of the liquid crystal element 16, a higher-contrast image can be observed at the X-direction pupil end. This effect can be obtained if the plane of the polarizer 12 and the plane of the analyzer 17 are not parallel to the element plane of the liquid crystal element 16 but are almost parallel. For example, if the plane of the polarizer 12 and the plane of the analyzer 17 should form an angle of 5 degrees or less with the element plane of the liquid crystal element 16, and if it is substantially parallel, the effect can be obtained to the maximum. . In the following description, the term “substantially parallel”, including both the case of being completely parallel and the case of being nearly parallel, is used.

In summary, it is sufficient that at least one of the surface of the polarizer 12 and the surface of the analyzer 17 is substantially parallel to the element surface of the liquid crystal element 16 when the optical path is developed along the optical axis AX. I can say that. In this case, at least one of the relative angle (tilt angle α) between the surface of the polarizer 12 and the element surface and the relative angle (tilt angle β) between the surface of the analyzer 17 and the element surface in the YZ plane is It becomes almost zero, and is certainly less than the relative angle (angle θ) between the optical axis AX and the normal of the element surface. As a result, for the light from the liquid crystal element 16 that is directed to any position shifted in the X direction from the center of the optical pupil E, the angle difference between the slow axis of the liquid crystal 23 and the transmission axis of the polarizer 12 during black display, and In other words, the angle difference between the slow axis of the liquid crystal 23 and the transmission axis of the analyzer 17 during black display can be reliably reduced. As a result, it is possible to observe a higher contrast image regardless of the position of the observer's pupil in the X direction. Further, if the angle formed by both the plane of the polarizer 12 and the plane of the analyzer 17 with the element plane of the liquid crystal element 16 is 5 degrees or less, a high-contrast image can be observed. If both the surface and the surface of the analyzer 17 are substantially parallel to the element surface of the liquid crystal element 16, the effect can be maximized.

For example, when the surface of the polarizer 12 and the element surface of the liquid crystal element 16 are parallel and the surface of the analyzer 17 and the element surface of the liquid crystal element 16 are not parallel, if A = B = Δθ and C ≦ 2Δθ, | Δ | = | 2B−A−C | ≦ Δθ. Further, when the surface of the polarizer 12 and the element surface of the liquid crystal element 16 are not parallel and the surface of the analyzer 17 and the element surface of the liquid crystal element 16 are parallel, B = C = Δθ and A ≦ 2Δθ. , | Δ | = | 2B−A−C | ≦ Δθ. In any case, since the leaked light from the analyzer 17 is small, a high-contrast image can be observed at the X-direction pupil end.

When the surface of the polarizer 12 and the element surface of the liquid crystal element 16 are parallel and the surface of the analyzer 17 and the element surface of the liquid crystal element 16 are parallel, for example, A = B = C = Δθ, and δ Since = 2BAC = 0 °, an image with the highest contrast can be observed at the pupil edge in the X direction.

(About other configuration of video display device)
FIG. 19 is an explanatory diagram schematically showing still another configuration of the video display device 1 of the present embodiment. In the figure, the illustration of the configuration after the eyepiece optical system 18 is omitted. As shown in the figure, instead of the illumination prism 19, a cylinder mirror 42 having a selective transmission / reflection surface 42a may be used as the illumination optical system. In this configuration, the light transmitted through the polarizer 12 is reflected by the selective transmission / reflection surface 42 a of the cylinder mirror 42 and enters the liquid crystal element 16. The light emitted from the liquid crystal element 16 passes through the selective transmission / reflection surface 42 a and travels toward the analyzer 17. In this configuration, the illumination optical system can be reduced in weight compared to the configuration using the illumination prism 41.

FIG. 20 is an explanatory diagram schematically showing still another configuration of the video display device 1 of the present embodiment. In the figure, the illustration of the configuration after the eyepiece optical system 18 is omitted. As shown in the figure, a reflection type polarizing plate 43 (for example, a brightness enhancement film (DBEF)) that doubles as a polarizer 12 and an analyzer 17 is arranged in parallel to the element surface of the liquid crystal element 16. May be. A polarizing plate 44 that transmits light having the same polarization direction as the light transmitted through the polarizing plate 43 is disposed on the back surface side (the eyepiece optical system 18 side) of the polarizing plate 43.

In this configuration, of the light from the light source 11, for example, P-polarized light is reflected by the polarizing plate 43 and enters the liquid crystal element 16. The light emitted from the liquid crystal element 16 (for example, white-displayed S-polarized light) passes through the polarizing plate 43 and the polarizing plate 44 and enters the eyepiece optical system 18. On the other hand, most of the light emitted from the liquid crystal element 16 (for example, black-polarized P-polarized light) is absorbed by the polarizing plate 43, but even if it is transmitted there, it is reliably absorbed by the polarizing plate 44 on the back surface. The As described above, even if the polarizing plate 43 is used in place of the polarizer 12 and the analyzer 17, the plane of the polarizing plate 43 is parallel to the element surface of the liquid crystal element 16, so that the pupil position in the X direction can be obtained. Regardless of the effect of the present invention, a high contrast image can be observed.

As in the above (2) and (3), the plane of the polarizer 12 and the plane of the analyzer 17 are not parallel <the relative angle between the plane of the polarizer 12 and the element plane of the liquid crystal element 16, and the analyzer. An arrangement in which the relative angle between the surface of the liquid crystal element 16 and the element surface of the liquid crystal element 16 is equal, an arrangement in which at least one of the surface of the polarizer 12 and the surface of the analyzer 17 is substantially parallel to the element surface of the liquid crystal element 16, or Whether the surface of the element 12 and the surface of the analyzer 17 are arranged at an angle of 5 degrees or less with respect to the element surface of the liquid crystal element 16 can be selected as appropriate according to the configuration of the illumination optical system. Good.

(Supplement)
In the above, an example in which a ferroelectric liquid crystal is used as the liquid crystal 23 of the liquid crystal element 16 has been described. However, an IPS (In Plane Switching) liquid crystal may be used as the liquid crystal 23. The IPS liquid crystal has a function as a phase plate similar to the ferroelectric liquid crystal, and performs white display by converting the phase of polarized light, while the polarization direction of incident light and the major axis direction of the liquid crystal molecules are different. Since the black display is performed without converting the polarization phase when they coincide, a high-contrast image can be displayed. Therefore, even when the IPS liquid crystal is used, the effect of the present invention that can observe a high-contrast image regardless of the pupil position in the X direction is effective.

In addition, the liquid crystal element 16 may be configured using a TN liquid crystal or may include a color filter. For example, when the plane of the polarizer 12 and / or the plane of the analyzer 17 and the element plane of the liquid crystal element 16 are parallel, the effect of obtaining a high contrast is obtained even when the liquid crystal element 16 is configured using TN liquid crystal. Obtainable. However, as described in (2) and (3) above, the effect of obtaining high contrast by setting α = + θ and β = −θ, or α = −θ, and β = + θ is ferroelectricity It can be obtained only when a liquid crystal that functions as a phase plate such as a liquid crystal is used. That is, the TN liquid crystal can be applied to configurations other than the above (2) and (3).

In this embodiment, the hologram optical element 33 having an axially asymmetric positive power is used. However, an eyepiece optical system using a free-form surface mirror, a prism using a free-form surface, an axially asymmetric lens, and the like. Even when 18 is configured, the same effect as that of the present embodiment can be obtained.

In the present embodiment, the video display device 1 suitable for the HMD has been variously described. However, the video display device 1 of the present embodiment can be applied to other devices such as a HUD (head-up display). It is.

Of course, the video display device 1 and thus the HMD can be configured by appropriately combining the configurations described in this embodiment.

The present invention can be used for HMD and HUD.

DESCRIPTION OF SYMBOLS 1 Video display apparatus 2 Support means 11 Light source 12 Polarizer (video display element)
13 Mirror (illumination optical system)
16 Liquid crystal elements (video display elements)
17 Analyzer (image display element)
18 Eyepiece optical system 23 Liquid crystal (ferroelectric liquid crystal)
E Optical pupil

Claims

A reflective video display element that modulates the light from the light source and displays the video;
An axially asymmetric illumination optical system for guiding light from the light source to the image display element;
An axially asymmetric eyepiece optical system for guiding image light from the image display element to an optical pupil,
The video display element is:
A liquid crystal element that modulates incident light for each pixel;
A polarizer that transmits light in a predetermined polarization direction out of the light from the light source and guides it to the liquid crystal element;
An analyzer that transmits light in a predetermined polarization direction out of the light emitted from the liquid crystal element and guides the light to the eyepiece optical system,
When an axis optically connecting the center of the element surface of the liquid crystal element and the center of the optical pupil is an optical axis,
The optical axis is inclined at an inclination angle other than perpendicular to the element surface within the axially asymmetric symmetry plane of the eyepiece optical system,
When the optical path is developed along the optical axis, the relative angle between the plane of the polarizer and the element plane, and the plane of the analyzer and the element plane are within the axially asymmetric symmetry plane of the eyepiece optical system. The relative angle between at least one of the relative angles between the optical axis and the normal of the element surface is less than the relative angle between the optical axis and the element surface.
A reflective video display element that modulates the light from the light source and displays the video;
An axially asymmetric illumination optical system for guiding light from the light source to the image display element;
An axially asymmetric eyepiece optical system for guiding image light from the image display element to an optical pupil,
The video display element is:
A liquid crystal element that modulates incident light for each pixel;
A polarizer that transmits light in a predetermined polarization direction out of the light from the light source and guides it to the liquid crystal element;
An analyzer that transmits light in a predetermined polarization direction out of the light emitted from the liquid crystal element and guides the light to the eyepiece optical system,
When an axis optically connecting the center of the element surface of the liquid crystal element and the center of the optical pupil is an optical axis,
The optical axis is inclined at an inclination angle other than perpendicular to the element surface within the axially asymmetric symmetry plane of the eyepiece optical system,
When the optical path is developed along the optical axis, the plane of the polarizer and the plane of the analyzer are not parallel, the relative angle between the plane of the polarizer and the element plane of the liquid crystal element, and the detector. An image display apparatus characterized in that a relative angle between a photon plane and an element plane of the liquid crystal element is equal.
The analyzer is arranged to be in crossed Nicols with the polarizer,
3. The image display device according to claim 1, wherein in black display, the liquid crystal element maintains a polarization direction of light transmitted through the polarizer, and the analyzer absorbs light in the polarization direction. 4. .
4. The image display device according to claim 3, wherein a transmission axis of the polarizer is parallel or perpendicular to an axially asymmetric symmetry plane of the eyepiece optical system.
4. When the optical path is developed along the optical axis, at least one of the plane of the polarizer and the plane of the analyzer is substantially parallel to the element plane of the liquid crystal element. Or the video display apparatus of 4.
When the optical path is developed along the optical axis, the angle formed between the plane of the polarizer and the element surface of the liquid crystal element and the angle formed between the plane of the analyzer and the element surface of the liquid crystal element are both 5. The video display device according to claim 1, wherein the video display device is within 5 degrees.
The surface of the polarizer and the surface of the analyzer are both substantially parallel to the element surface of the liquid crystal element when an optical path is developed along the optical axis. Video display device.
When the optical path is developed along the optical axis, the plane of the polarizer and the plane of the analyzer are not parallel, the relative angle between the plane of the polarizer and the element plane of the liquid crystal element, and the detector. The video display device according to claim 1, wherein a relative angle between a photon plane and an element plane of the liquid crystal element is equal.
Both the relative angle between the surface of the polarizer and the element surface, and the relative angle between the surface of the analyzer and the element surface are less than the relative angle between the optical axis and the normal of the element surface. The video display device according to claim 1, wherein the video display device is a video display device.
The video display device according to claim 1, wherein the liquid crystal element includes a ferroelectric liquid crystal.
11. The illumination optical system is disposed outside an optical path from the liquid crystal element toward the eyepiece optical system, and reflects light from the light source to guide the liquid crystal element. 2. The video display device according to claim 1.
The video display device according to any one of claims 1 to 11, wherein a relative angle between the optical axis and a normal of the element surface is 10 degrees or more.
The image display device according to any one of claims 1 to 12, wherein the image display element is arranged on one end side of the eyepiece optical system.
A video display device according to any one of claims 1 to 13,
And a support means for supporting the video display device in front of an observer's eyes.