JP2001021853A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device having a thin eye-front optical system and having high see-through property and improved resolution. SOLUTION: The light from a light source 4 enters an optical waveguide 33 in a display part 3. When a display controlling circuit applies voltage according to the video signals from a disk driving unit on the corresponding linear electrodes in the X electrode group 31x and Y electrode group 31y, the light transmitted in a part of the optical waveguide 33 with applied voltage is radiated by the cut-off phenomenon to the outside, and is condensed by a hologram optical element 35 to the eye 12 of a wearer to project a two-dimensional image on the retina 12b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video display device, and more particularly to a video display device having a thin anterior optics, high see-through performance, and improved resolution.

[0002]

2. Description of the Related Art A head-mounted display (HMD) is a small-sized image display device mounted on a head for observing an image. This HMD uses a liquid crystal display (L
An image forming unit including a display element typified by CD) or the like;
An image transmission unit including a lens and a mirror is arranged in front of the eyes, and is fixed to the head by a belt or other mounting mechanism for use. The image displayed on the display element of the image forming unit is displayed by forming a large virtual screen in a place that is easy to see by the aberration correction and enlargement functions by the lens and the mirror of the image transmission unit.

[0003] Taking advantage of this feature, HMD is a device for displaying flight information such as altitude and speed for aircraft, personal movies,
It has been developed and commercialized to realize video games and artificial reality. Recently, research on a display for a portable computer (Wearable Computer) has been conducted.

[0004] Such HMDs include a see-through type in which the outside world can be seen and a closed type in which the outside world cannot be seen. In some cases, a closed type rather than a see-through type is preferable, such as artificial reality, but in many cases, a see-through type that allows simultaneous observation of the outside world is more convenient for portable use. This see-through HMD is
In addition to the image forming unit and the image transmitting unit, a beam combiner is required as an element for realizing the see-through function.

The beam combiner is, for example, a CRT or an LRT.
A method in which a display image of a CD can be enlarged and displayed, and at the same time, an incident light from the outside can be observed. Typical methods include a half mirror, a prism, and a hologram. Since the sum of the light amounts of the image light and the external light is 100% in the principle of the half mirror and the prism, if a high reflectance is set to obtain a bright image, the external light decreases and the see-through property decreases. That is inevitable. On the other hand, the hologram method has a sharp wavelength selectivity with respect to a specific wavelength and can reflect and diffract only that wavelength, so that 100% of the image light of the specific wavelength and 100% of the external light excluding the wavelength are removed. You can see them again. This function is a method in which a display image is displayed by the beam combiner and 100% of light from the outside can be taken in at the same time, and high see-through property can be realized.

A conventional image display apparatus using the hologram method is disclosed in, for example, JP-A-10-319240. This video display device 100
As shown in FIG. 7, a pair of left and right liquid crystal displays (LCD) 101 for emitting image display light, and a pair of right and left spectacle lenses 103 fitted in a spectacle frame 102.
And the image display light from the LCD 101 to the spectacle lens 10
A pair of left and right optical fiber bundles 10 leading to the end face 103a of the third
4 and the eyeglass lens 103 which is arranged on the visual axis of the wearer.
Is provided with a hologram optical element 105 that diffracts the image display light guided to the end face 103a of the lens and guides the diffracted light to the eye E of the wearer so that the wearer can visually recognize a virtual image based on the image display light. Thereby, the anterior ocular optical system is thin, and high see-through property can be realized.

[0007]

However, according to the conventional image display device, since the image display light is incident from the end face of the spectacle lens, the optical fiber bundle must be arranged in a narrow area, and the diameter of the optical fiber is reduced. There is a problem in that there is a limit in miniaturization of the device, and thus there is a limit in increasing the resolution.

Accordingly, it is an object of the present invention to provide a video display device in which the anterior optics system is thin, has high see-through properties, and improves resolution.

[0009]

According to the present invention, in order to achieve the above object, a light emitting means for emitting light, light from the light emitting means is input from one end, and the light is transmitted to the other end. An optical waveguide, voltage applying means for applying a voltage to the optical waveguide, and controlling the voltage applying means so as to apply a voltage to a portion of the optical waveguide corresponding to the video signal based on a video signal; A video display device comprising: a control unit for displaying an image by radiating light transmitted through the applied optical waveguide portion to the outside by a cutoff phenomenon. According to the configuration, when the control unit controls the voltage applying unit based on the video signal to partially apply a voltage to the optical waveguide, the light being transmitted through the optical waveguide to which the voltage is applied is reduced. Is emitted to the outside due to the cut-off phenomenon, and a two-dimensional image is displayed. In order to achieve the above object, the present invention provides a video display device which is mounted on a head and displays an image to a wearer thereof, a light emitting unit for emitting light, and light from the light emitting unit is incident from one end. An optical waveguide for transmitting the light to the other end, voltage applying means for applying a voltage to the optical waveguide, and applying a voltage to a portion of the optical waveguide corresponding to the video signal based on a video signal. A control unit for controlling the voltage application unit, and displaying an image to the wearer by radiating light being transmitted through a portion of the optical waveguide to which a voltage is applied by a cut-off phenomenon, and a portion of the optical waveguide; And a light condensing means for condensing light radiated from the outside to the eyes of the wearer. According to the above configuration,
The control means controls the voltage applying means based on the video signal to partially apply a voltage to the optical waveguide, and the light being transmitted through the portion of the optical waveguide to which the voltage is applied becomes external due to a cutoff phenomenon. And is condensed on the wearer's eye by the condensing means, and a two-dimensional image is projected on the retina of the eye.

[0010]

FIG. 1 shows an image display apparatus according to a first embodiment of the present invention. In FIG. 1, only one side is shown. The video display device 1 includes a spectacles frame 2 including a rim 2a, a tongue 2b, a blow unit 2c, and a temple 2d, and a rim 2a of the megame frame 2.
And a pair of left and right display units 3 for displaying a two-dimensional color image by an electro-optic effect, and provided on the temple unit 2d of the glasses frame 2, and sequentially emits light of three primary colors of R, G, and B to the display unit 3. A pair of left and right light sources 4 to be emitted, a pair of right and left transmission optical systems 5 for guiding the light from the light sources 4 to the display unit 3, and provided outside the glasses frame 2 to drive a disc and output reproduced video signals. Left and right common disk drive unit 6 and glasses frame 2
Of the disk drive unit 6
And a display control circuit 7 for driving the display unit 3 on the basis of the video signal from the CPU and displaying a color video.

The transmission optical system 5 transmits the light from the light source 4 incident from the incident end and emits the light from the emission end, and condenses the light emitted from the emission end of the optical fiber 50 to display the light. 3 and a condenser lens 51 that enters the optical waveguide described later. When the light source 4 is an incoherent light source such as an LED, this optical fiber 50
Is used, coherence is enhanced, and blurring of a displayed image can be reduced.

The disk drive unit 6 reproduces a disk on which video signals are recorded, and transmits the reproduced video signals to the unit side cable 8a, jack terminal 9, glasses side cable 8b, flat cable input terminal 11, and flat cable 10A. The display control circuit 7 outputs power to the light source 4 and the display control circuit 7 via the display control circuit 7.

The display control circuit 7 includes a flat cable 10
X electrode group 31x via B and X drive wiring unit 31a
And the flat cable 10C and the Y drive wiring portion 31b
A voltage is applied to the Y electrode group 31y via the. The display control circuit 7 controls the X electrode group 31x and the Y electrode group 31x so that a potential difference that can cause a cut-off phenomenon by an electro-optic effect in an optical waveguide, which will be described later, forming the display unit 3 is generated.
y, for example, X electrode group 31x
+ Vx to the Y electrode group 31y. In addition,
A combination of a planar electrode and a matrix electrode may be used. In this case, a voltage corresponding to a video signal is applied to the matrix electrodes with the planar electrodes being grounded.

FIG. 2 shows the display unit 3. The display unit 3 has a substrate 30 fitted into the rim 2a of the eyeglass frame 2, and is formed of a Y electrode group 31y, a Y buffer layer 32y, and a material having an electro-optical effect on the substrate 30. Optical waveguide 33, X buffer layer 32
The x and X electrode groups 31x are arranged in this order, and the hologram optical element 35 is arranged thereon via an optical adhesive having the same refractive index as the buffer layers 32x and 32y. On the light source 4 side of the optical waveguide 33, a waveguide lens 36 for diffusing the light incident from the light source 4 via the transmission optical system 5 into the optical waveguide 33 is disposed, and at the opposite end, the light is transmitted. A light-absorbing material 37 for absorption is arranged. The X buffer layer 32x and the Y buffer layer 32y
3 having a refractive index smaller than the refractive index of the X electrode group 31x
And a light propagation loss due to the Y electrode group 31y.

The substrate 30, the electrode groups 31y and 31x, the buffer layers 32y and 32x, the optical waveguide 33 and the hologram optical element 34 are all made of a light-transmitting material. For example, as the electrode groups 31y and 31x, I
TO is used, and as the buffer layers 32A and 32B,
A glass-based material is used, and the optical waveguide 33 is Li
An NbO ₃ material or the like is used.

The X electrode group 31y and the Y electrode group 31y are
The linear electrodes are arranged in a matrix so as to cross each other.

The hologram optical element 35 is obtained by forming a hologram film 35b on one surface of a substrate 35a.
The focus of the hologram optical element 35 is the pupil 12a of the eye 12.
Is set to By arranging the substrate 35a so as to be on the front side, the hologram film 35b can be protected. Even if the light is radiated from the optical waveguide 33 at a radiation angle of 15 degrees, if the outside of the X electrode 31x is air, the refractive index will be low and the radiation will not be radiated to the outside. For this reason, the hologram optical element 35 is brought into close contact with the adhesive 34 having the same refractive index as the buffer layers 32x and 32y. The photogram optical element 35 applies a hologram photosensitive material to the surface of the substrate 35a, passes through the interference fringe forming step and the developing step, and forms the hologram into R and R.
Recording is performed in three primary colors of G and B, a hologram film 35b is formed, and the three colors have similar diffraction characteristics. The hologram photosensitive material, for example, photopolymer, photoresist,
Photochromic, photodichromic, silver salt film, silver salt emulsion, dichromated gelatin, dichromated gelatin, plastic, ferroelectric, magneto-optical material, electro-optical material, amorphous semiconductor, photorefractive material, etc. A material having properties is used.

FIG. 3 shows the light source 4. The light source 4 includes a red light source 40R that emits red (R) light, a green light source 40G that emits green (G) light, and a blue (R) light.
And a first light source 40B that reflects light from a green light source 40G and transmits light from a red light source 40R.
, And a second beam splitter 41b that reflects light from the blue light source 40B and transmits light from the red light source 40R and the green light source 40G. Red light source 40R, green light source 40G and blue light source 4
For OB, an LED, a laser, or the like can be used.

Next, the operation of the apparatus 1 will be described. Light source 4
Are the red light source 40R, the green light source 40G, and the blue light source 4
0B, light of three primary colors of R, G, and B are sequentially emitted, and the light of the three primary colors is transmitted to the first and second beam splitters 4.
1a and 41b, the optical fiber 50 of the transmission optical system 5
Through the condenser lens 51 and introduced into the optical waveguide 33 of the display unit 3 via the condenser lens 51. The light introduced into the optical waveguide 33 is uniformly spread over the entire display unit 3 in the horizontal direction of the substrate 30 by the waveguide lens 36.

On the other hand, the disk drive section 6 drives the disk and reproduces the video signal via the unit side cable 8a, the jack terminal 9, the glasses side cable 8b, the flat cable input terminal 11 and the flat cable 10A. 7 is output. The display control circuit 7 synchronizes with the sequential light emission of the red light source 40R, the green light source 40G, and the blue light source 40B, and the X electrode group 31x and the Y electrode group 31y.
Are driven in a dot-sequential manner, and as shown in FIG.
Applying a predetermined voltage Vx to the linear electrodes x ₁ ~x ₈ a corresponding X electrode group 31x through the B and X drive wiring portion 31a, the flat cable 10C and Y drive wiring portion 31b
Linear electrodes y ₁ ~y ₈ a corresponding Y electrodes 31y through the
Is applied with a predetermined voltage Vy.

The portion of the optical waveguide 33 between the linear electrodes x _{1 to} x ₈ to which the voltage is applied and the linear electrodes y _{1 to} y ₈ has a refractive index at which light cannot be effectively confined by the electro-optic effect. The light being transmitted through the portion of the optical waveguide 33 to which the voltage is applied is radiated to the outside. This is called a cutoff phenomenon. For example, if LiNbO ₃ having a thickness of 0.5 μm and having high crystallinity is used as the optical waveguide 33, the applied voltage is cut off at about 5V. At this time, the radiation angle θ (see FIG. 2) is about 15 degrees. At a position where no voltage is applied, the light wave travels inside the optical waveguide 33, reaches an end of the optical waveguide 33, and is absorbed by the light absorbing material 37.

Here, the display standard SXG is displayed by the dot sequential driving.
Consider the case where A is displayed. Frequency response is 1280
(Horizontal), 1024 (vertical), 60 Hz, 3 (3 primary colors) = 7
9 MHz is required. The frequency response by such a simple electrode structure is represented by Δf = (πRC) −1. The size of one color pixel is 20 microns square, and the resistance R is 1 kΩ.
, The capacitance C is about 3 pF. As a result, Δ
f is about 1 GHz, and the cut-off tracking frequency (1 GHz
z)> SXGA display frequency (79 MHz). Therefore, a two-dimensional image can be formed by applying a voltage at each intersection of the matrix wiring and driving the dots sequentially to form a color image.

The gradation in the display unit 3 is the applied voltage.
Is changed to obtain the amount of emitted light by adjustment. Applied voltage
Adjusting the light intensity without changing the radiation angle even if the pressure is changed
Because you can. The light emitted from the optical waveguide 33 is large.
Into the transmission type hologram optical element 35
Pupil 12a by the action of the hologram film 35b.
The light is emitted so as to be focused. For example, as shown in FIG.
And a linear electrode x₁And y ₁, X_FourAnd y_Five, X₇And y₈Between
When a voltage is applied to the pupil 12a,
An image is projected on 12b. At this time, the voltage between the other electrodes is
No pressure is applied, and the light wave travels through the optical waveguide 33 and the light absorbing material 3
Absorbed at 7.

According to the first embodiment, the following effects can be obtained. (A) Since the display structure using the optical waveguide 33 and only the hologram optical element 35 are arranged in front of the eyes, the image display device 1 that is simple and very thin can be realized. (B) It is not necessary to use a polarizing plate or a color filter such as an LCD having a low transmittance of external light, and the transmittance of external light is determined by the aperture ratio of the matrix electrode. % Or more) can be provided. (C) Since the density of the displayed image can be increased by reducing the size of the portion of the optical waveguide 33 to which the voltage is applied, the resolution can be improved.

FIG. 4 shows a display unit 3 according to a second embodiment of the present invention. It should be noted that FIG.
A state is shown in which a voltage is applied to x linear electrodes x ₁ , x ₄ , and x ₇ , and light is emitted from the portions. The second embodiment is different from the first embodiment in that a fine focus adjusting element 13 for adjusting the focal length of the hologram film 35b is arranged inside the hologram optical element 35.

The fine focus adjusting element 13 is an electro-optical (EO)
The distance between the hologram film 35b and the eye 12 is adjusted by adjusting the optical path length by changing the refractive index using an effect or the like. For example, the thin EO material 13a and the thin EO material 13 are used.
a and transparent electrodes 13b and 13c disposed therebetween. When a voltage is applied between the transparent electrodes 13b and 13c, the refractive index changes due to the electro-optic effect. As EO material 13a, for example, using a material whose refractive index decreases when voltage is applied, as shown in FIG. 4, the direction of the light beam moves from the dashed line to a solid line, the focal point moves from p ₀ to p ₁ As a result, the focal length of the hologram film 35b is reduced. Conversely, EO the material 13a using a material refractive index increases when voltage is applied, as shown in FIG. 4, moves from the dashed line to the dotted line, holographic film 35b focus is moved from p ₀ to p ₂ Focal length becomes longer.

FIG. 5 shows a display unit 3 according to a third embodiment of the present invention. It should be noted that FIG.
A state is shown in which a voltage is applied to x linear electrodes x ₁ , x ₄ , and x ₇ , and light is emitted from the portions. In the first embodiment, the flat substrate 30 is used. In the third embodiment, the display unit 3 is formed in a curved shape. That is, the Y electrode group 31y, the Y buffer layer 32y, the optical waveguide 33, the X buffer layer 32x, the X electrode group 31x, and the hologram optical element 35 are arranged on the curved substrate 30. Thereby, aberration can be reduced.

FIG. 6 shows a display unit 3 according to a fourth embodiment of the present invention. It should be noted that FIG.
A state is shown in which a voltage is applied to x linear electrodes x ₁ , x ₄ , and x ₇ , and light is emitted from the portions. In the fourth embodiment, instead of the hologram optical element 25, a microlens array 14 having a plurality of microlenses 14a in an array is arranged. Each micro lens 14a is formed in an aspherical shape so that the light emitted from the optical waveguide 33 is focused on a common focal point.

[0029]

As described above, according to the image display device of the present invention, a voltage is applied to the optical waveguide to emit light, and an image is displayed. Since it is not necessary to use a polarizing plate or a color filter such as an LCD having a low light transmittance, a high see-through property can be realized, and a display image can be obtained by reducing the size of a portion of an optical waveguide to which a voltage is applied. Can be increased, so that the resolution can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a video display device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a display unit according to the first embodiment;

FIG. 3 is a schematic diagram illustrating a light source and a display state according to the first embodiment.

FIG. 4 is a sectional view showing a display unit according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a display unit according to a third embodiment of the present invention.

FIG. 6 is a sectional view showing a display unit according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing a conventional video display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image display apparatus 2 Glasses frame 2a Rim part 2b Tongue part 2c Blow part 2d Temple part 3 Display part 4 Light source 5 Transmission optical system 6 Disk drive unit 7 Display control circuit 8a Unit side cable 8b Glasses side cable 9 Jack terminal 10A, 10B , 10C flat cable 11 flat cable input terminal 12 eye 12a pupil 12b retina 13a EO material 13b, 13c transparent electrode 14 micro lens array 14a micro lens 30 substrate 31a X drive wiring section 31b Y drive wiring section 31x X electrode group 31y Y electrode group 32x X buffer layer 32y Y buffer layer 33 Optical waveguide 34 Optical adhesive 35 Hologram optical element 35a Substrate 35b Hologram film 36 Waveguide lens 37 Light absorbing material 40R Red light source 40G Green light source 4 B blue light source 41a first beam splitter 41b second beam splitter 50 optical fibers 51 a condenser lens p _0, p _1, p ₂ focal

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G02B 6/00 EF term (reference) 2H038 AA41 BA06 BA41 BA42 2H079 AA02 AA12 BA01 CA21 DA03 EA02 EA08 EB04 EB06 EB15 HA08 KA02 KA08 KA08 KA18 5G435 AA00 AA18 BB11 BB15 CC09 CC12 DD01 EE33 FF01 FF05 FF08 FF14 GG01 GG02 GG18 HH02 HH12

Claims (14)

[Claims] 1. A light emitting means for emitting light, an optical waveguide for receiving light from the light emitting means from one end and transmitting the light to the other end, and a voltage applying means for applying a voltage to the optical waveguide. And controlling the voltage applying means so as to apply a voltage to the portion of the optical waveguide corresponding to the video signal based on the video signal, and cuts light being transmitted through the portion of the optical waveguide to which the voltage is applied. A video display device comprising: control means for displaying an image by radiating the image to the outside by an OFF phenomenon. 2. An image display device mounted on a head and displaying an image to a wearer thereof, a light emitting means for emitting light, and light from the light emitting means being input from one end to the other light. An optical waveguide to be transmitted to an end; voltage applying means for applying a voltage to the optical waveguide; and controlling the voltage applying means to apply a voltage to a portion of the optical waveguide corresponding to the video signal based on a video signal. And control means for displaying an image to the wearer by radiating light being transmitted through the portion of the optical waveguide to which a voltage is applied by a cutoff phenomenon, and emitted from the portion of the optical waveguide to the outside. An image display device comprising: a light condensing means for condensing light on the eye of the wearer. 3. The image display device according to claim 2, wherein said light emitting means comprises a red light source for emitting red light, a green light source for emitting green light, and a blue light source for emitting blue light. . 4. The light emitting means includes: a light source for emitting light;
An optical transmission system for inputting light from the light source to the optical waveguide, wherein the waveguide includes light diffusing means for spreading the light incident by the optical transmission system over the entire waveguide. 2. The image display device according to 2. 5. An optical transmission system comprising: an optical fiber for transmitting light from the light source; and a condenser lens for condensing light transmitted by the optical fiber and entering the one end of the optical waveguide. The video display device according to claim 4, further comprising: 6. The image display device according to claim 4, wherein said optical transmission system includes a condensing optical system for condensing light from said light source on said one end of said optical waveguide. 7. The image display device according to claim 4, wherein said light diffusing means is provided in said optical waveguide and has a waveguide lens or a grating lens having a lens function. 8. The voltage applying means comprises: a first electrode and a second electrode having a light-transmitting property arranged to face each other via the optical waveguide; and the optical waveguide, the first electrode, and the second electrode having a light-transmitting property. A first buffer layer and a second buffer layer having a light-transmitting property and being arranged so as to be in close contact with the second electrode and having a refractive index smaller than the refractive index of the optical waveguide; 3. The video display device according to claim 2, wherein the video display device is provided. 9. An image display apparatus according to claim 2, wherein said light condensing means has a hologram optical element having a light transmitting property. 10. The image display device according to claim 9, wherein said hologram optical element is an asymmetric optical system. 11. The image display device according to claim 2, wherein said light condensing means has a macro lens array comprising a plurality of micro lenses. 12. The image display apparatus according to claim 2, wherein said light condensing means has a focus adjusting means for adjusting a focus of said hologram optical element. 13. The image display device according to claim 2, wherein said light emitting means, said optical waveguide, said voltage applying means, said control means, and said light condensing means are provided on a spectacle frame. 14. A structure according to claim 2, wherein said optical waveguide, said voltage applying means, and said light condensing means are formed in a curved shape.
The image display device according to the above.