JP2003057571A - Optical multi-layered structure and optical switching element, and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical multi-layered structure which has simple constitution, is small-sized and lightweight, and can switch incident light at a high speed. SOLUTION: On a substrate 10 made of glass, low-refractive-index layers 12A to 13H made of magnesium fluoride (MgF2 ) and high-refractive-index layers 13A to 14H made of antimony oxide (Sb2 O3 ) are laminated by turns. The low- refractive-index layer 12A to the high-refractive index layer 13D on the side of the substrate 10 form a 1st layer 15 across a gap part 14 (low-refractive-index layer 12E), and the low-refractive-index layer 13E to the high-refractive-index layer 13H on the opposite side to the substrate 10 form a 2nd layer 18. A lower electrode layer 17 and an upper electrode layer 18 are provided which are formed out of metal thin films having windows 17A and 18A for transmitting ultraviolet light and the optical size of the gap part 14 is varied with an electrostatic force generated between the both to switch the quantity of reflection or transmission of the ultraviolet light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical multilayer structure having a function of reflecting or transmitting ultraviolet light, an optical switching element using the same, and an image display device.

[0002]

2. Description of the Related Art In recent years, the importance of a display as a display device for video information is increasing, and it operates at high speed as an element for this display and further as an element for optical communication, an optical storage device, an optical printer and the like. There is a demand for the development of an optical switching element (light valve) that does. Conventionally, as this type of element, an element using a liquid crystal or an element using a micromirror (DMD: Digital Micro Miror D
evice, digital micromirror device, registered trademark of Texas Instruments), and one using a diffraction grating (GLV: Grating Light Valve, SLM (Silicon Light Machine)).

[0003]

In a conventional reflection type image display device using liquid crystal, transparent electrodes are formed inside a pair of substrates made of glass, and liquid crystal molecules are formed between the transparent electrodes of both substrates. It has an enclosed structure. The outside of the glass substrate is further covered with a pair of polarizing plates and is illuminated by a backlight from the back. Optical switching is performed by applying a voltage between the transparent electrodes and controlling the direction of liquid crystal molecules to rotate the plane of polarization.

However, even if the liquid crystal has a high response speed, it is only about a few milliseconds, and the high speed response characteristic is poor. It is very difficult to apply it to. Moreover, since a polarizing plate is required, the light utilization efficiency is low. Further, since the liquid crystal cannot withstand strong light, it is impossible to switch light with high energy density such as strong laser light. In recent years, there has been an increasing demand for high-quality image quality such as brightness, color reproducibility, and accurate gradation display as a color image display device. There are insufficient points in.

An optical switching element using a micromirror switches incident light by controlling the angle of the micromirror. An optical switching element using a micromirror is a DMD (Digital Micro Mi
ror Device, digital micromirror device, registered trademark of Texas Instruments Incorporated in the United States). Micromirrors are roughly classified into two types: a cantilever structure that is supported at one point and a torsion hinge structure that is supported at two points, and they are driven using electrostatic force, a piezoelectric element, a thermal actuator, etc. .

In the case of the cantilever structure, each micromirror is supported in a horizontal state with respect to the substrate, and when a potential difference is applied between the micromirror and the corresponding drive electrode, an electrostatic attractive force is generated, The micromirror tilts towards the corresponding drive electrode. Since the incident light is reflected at different angles between the tilted micromirror and the non-tilted micromirror, the incident light can be switched in two directions. When the potential difference applied between the micromirror and the drive electrode is removed, the spring force of the hinge portion supporting the micromirror returns the micromirror to its original position.

On the other hand, in a micromirror having a twist hinge structure, each micromirror is supported by a pair of hinge portions on a common upper substrate. The lower substrate is provided with a pair of electrodes corresponding to each micromirror. The same potential difference is generated between each micromirror and one of the pair of electrodes, and between the micromirror and the other electrode, which causes the micromirror to move to the lower substrate. It is kept horizontal.

Here, for example, by increasing the voltage applied to one electrode and decreasing the voltage applied to the other electrode, the electrostatic attraction generated between the micromirror and each of the corresponding pair of electrodes is unbalanced. And tilt the micromirror toward either of the pair of electrodes. As a result, the micromirror tilts in one of two different directions, so that it is possible to reflect incident light in two different directions for switching. In such a micromirror, the angle at which the light can be deflected, that is, the difference between the angles of the reflected light in the two directions becomes twice the deflection angle of the mechanical mirror, and the angle at which the light can be deflected becomes large.

However, the response speed of such a micromirror is generally about several microseconds, and its high speed is not sufficient. When used in an image display device,
In order to improve the contrast, it is necessary to increase the angle at which the light can be deflected, which causes a problem that the response speed further decreases. Therefore, an optical switching element using a micromirror has been already used in a projection type image display device, but it is difficult to apply it to a direct view type image display device.

As an optical switching element using a diffraction grating, there is GLV (Grating Light Valve, SLM (Silicon Light Machine) Co., Ltd.) disclosed in, for example, Japanese Patent Publication No. 10-510374. In this GLV, a potential difference is generated between a ribbon-shaped mirror having a light-reflecting surface and a lower electrode, and the electrostatic attraction generated thereby moves the ribbon-shaped mirror by 1/4 of the wavelength of incident light. Thus, a diffracted light is generated by creating an optical path difference of 1/2 wavelength between the stationary ribbon-shaped mirror and the movable ribbon-shaped mirror, and the reflected light is switched between the 0th-order diffracted light direction and the 1st-order diffracted light direction. To do. At this time, it is also possible to control the intensity of the first-order diffracted light by controlling the optical path difference within a range up to 1/2 wavelength.

The GLV can switch light by moving a very light ribbon mirror by a small distance, and therefore has a fast response speed of several tens of nanoseconds and is suitable for high speed switching. It also has some problems.

First, at least two ribbon-shaped mirrors are required to cause the diffraction of light, and four or more, and in reality, six ribbon-shaped mirrors are required to enhance the light utilization efficiency. You need a mirror. Therefore, when used in a one-dimensional array, it is difficult to reduce the overall size.

Second, since the 1st-order diffracted light is generated at an angle with respect to the two directions symmetrical with the optical axis of the 0th-order diffracted light,
In order to use the first-order diffracted light, a complicated optical system for collecting and advancing the light traveling in these two directions is required.

Third, in the state where no voltage is applied to the electrodes,
The reflecting surface of the ribbon-shaped mirror in a stationary state and the reflecting surface of the movable ribbon-shaped mirror should ideally be on the same plane, but they are not actually on the same plane. Therefore, it is necessary to apply a small voltage to the lower electrodes so that the reflecting surfaces of all the mirrors are aligned on the same plane.

Fourth, the GLV uses a laser as a light source, irradiates switching light integrated in a one-dimensional array with linearly shaped light, and scans the light with a mirror or the like to form a two-dimensional image. Although it is suitable for a projection type image display device designed to obtain the above, it is theoretically very difficult to use a light source other than a laser or a direct view type image display device.

The present invention has been made in view of the above problems, and an object thereof is an optical multilayer structure which has a simple structure, is small and lightweight, and is capable of high-speed switching with respect to ultraviolet light. An object is to provide an optical switching element and an image display device using the same.

[0017]

An optical multilayer structure according to the present invention is an optical multilayer comprising a substrate transparent to ultraviolet light, and low refractive index layers and high refractive index layers alternately laminated on the substrate. It is formed as one of the low-refractive-index layers included in the film structure, and has a gap that has a size that can cause an interference phenomenon of light and the size of which is variable, and a low-refractive index laminated on the substrate side with respect to the gap. It has a first layer composed of a layer and a high refractive index layer, and a second layer composed of a low refractive index layer and a high refractive index layer laminated on the side opposite to the substrate with respect to the gap.

The optical switching element according to the present invention has a low refractive index contained in an optical multilayer film structure in which a substrate transparent to ultraviolet light and low refractive index layers and high refractive index layers are alternately laminated on the substrate. Formed as one of the refractive index layers and having a size capable of causing a light interference phenomenon and having a variable size, a low refractive index layer and a high refractive index layer laminated on the substrate side with respect to the gap part. An optical multi-layer structure having a first layer made of a material, a second layer made of a low refractive index layer and a high refractive index layer, which are laminated on the side opposite to the substrate with respect to the gap, and an optical structure of the gap. And a drive means for changing the size.

The image display device according to the present invention comprises a plurality of one-dimensionally or two-dimensionally arranged optical switching elements, an ultraviolet light source, and a phosphor, and the plurality of optical switching elements are irradiated with ultraviolet light from the ultraviolet light source. A two-dimensional image is displayed by irradiating the phosphor to excite the phosphor, and the optical switching element includes a substrate transparent to ultraviolet light, and a low refractive index layer and a high refractive index layer on the substrate. It is formed as one of the low-refractive index layers included in the optical multilayer film structure that is alternately laminated, and has a size that can cause an interference phenomenon of light and the size of which is variable. A first layer composed of a low refractive index layer and a high refractive index layer laminated on the side, and a second layer composed of a low refractive index layer and a high refractive index layer laminated on the side opposite to the substrate with respect to the gap. An optical multilayer structure having
And a drive unit for changing the optical size of the gap.

In the optical multi-layer structure according to the present invention, the size of the gap portion is an odd multiple of "λ / 2" (λ is the design wavelength of incident light) and an even multiple of "λ / 2" (including 0). Between and, the amount of reflection or transmission of incident light changes in a binary or continuous manner.

In the optical switching element according to the present invention, the driving means changes the optical size of the gap portion of the optical multi-layer structure to perform the switching operation with respect to the incident light.

In the image display device according to the present invention, a plurality of optical switching elements of the present invention arranged one-dimensionally or two-dimensionally are irradiated with ultraviolet light from an ultraviolet light source to excite the phosphor, thereby two-dimensionally. The image is displayed.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Optical Multilayer Structure] FIGS. 1 and 2 show a basic structure of an optical multilayer structure 1 according to an embodiment of the present invention. FIG. 1 shows a state where there is a gap portion 14 described later in the optical multilayer structure 1 at the time of low transmission, and FIG. 2 shows a state when there is no gap portion 14 of the optical multilayer structure 1 at the time of high transmission. The optical multilayer structure 1 is specifically used as, for example, an optical switching element for ultraviolet light, and by arranging a plurality of the optical switching elements in one or two dimensions, an image display device can be configured. it can.

The optical multilayer structure 1 according to the present embodiment has the low refractive index layers 12A to 12H and the high refractive index layer 1 on the substrate 10.
It has an optical multilayer film structure 11 in which 3A to 13H are alternately laminated. Specifically, the optical multilayer film structure 11 includes a low refractive index layer 12A, a high refractive index layer 13A, a low refractive index layer 12B, a high refractive index layer 13B, a low refractive index layer 12C, a high refractive index layer 13C,
Low refractive index layer 12D, high refractive index layer 13D, low refractive index layer 12
E, a high refractive index layer 13E, a low refractive index layer 12F, a high refractive index layer 13F, a low refractive index layer 12G, a high refractive index layer 13G, a low refractive index layer 12H, and a high refractive index layer 13H are included in this order. .
Table 1 shows the detailed configuration of each layer of the optical multilayer film structure 11 when optimally designed for ultraviolet light having a wavelength of 300 nm.

[0026]

[Table 1]

FIG. 3 shows the transmission characteristics of the optical multilayer structure 1 having the structure shown in Table 1 when ultraviolet light having a wavelength of 300 nm is incident at an incident angle of 0.00 degree.
As can be seen from FIG. 3, the transmittance of the optical multilayer structure 1 at high transmittance is 94.5 for ultraviolet light having a wavelength of 300 nm.
%, The transmittance at low transmittance is 0.23%, and by providing the optical multilayer film structure 11, excellent optical characteristics can be obtained. In FIG. 3, the curve indicated by reference numeral 300H indicates the transmission characteristic at the time of high transmission, and the curve indicated by the reference numeral 300L indicates the transmission characteristic at the time of low transmission.

Of the low refractive index layers 12A to 12H, the low refractive index layer 12E is filled with air and forms the gap portion 14. The low-refractive index layer 12A to the high-refractive index layer 13D on the substrate 10 side form the first layer 15 with the gap 14 interposed therebetween, and the high-refractive index layer 13E on the side opposite to the substrate 10 has a high refractive index. The layers up to the layer 13H form the second layer 16.

In the present embodiment, a substrate that is transparent to ultraviolet light and is made of, for example, glass is used as the substrate 10. The low-refractive-index layers 12A to 12D and 12F to 12H other than the low-refractive-index layer 12E serving as the gap portion 14 have a relatively low refractive index of 1.387, namely magnesium fluoride (Mg).
F ₂ ). High refractive index layers 13A to 13H
Is composed of antimony oxide (Sb ₂ O ₃ ) having a relatively high refractive index of 2.290.

The gap portion 14 is formed by a driving means described later.
The optical size (the distance between the first layer 15 and the second layer 16) is set to be variable. Gap 14
The medium that fills in may be gas or liquid as long as it is transparent to ultraviolet light. Examples of the gas include air and nitrogen (N
Examples of the liquid such as ₂ ) and helium (He) include water, silicone oil, ethyl alcohol, glycerin, and jodomethane. Note that the gap portion 14 can also be in a vacuum state.

The optical size of the gap portion 14 is, for example, "odd times λ / 2" and "even times λ / 2 (including 0)".
It changes in a binary manner or continuously between and. This causes the amount of reflection or transmission of incident ultraviolet light to change in a binary manner or continuously. It should be noted that even if it is slightly deviated from a multiple of λ / 2, it can be complemented by a slight change in the film thickness or the refractive index of the other layers.
The case of "/ 2" is also included.

A lower electrode layer 17 is provided under the first layer 15 and a lower electrode layer 17 is provided over the second layer 16 as a driving means for changing the optical size of the gap portion 14 to switch the ultraviolet light. The upper electrode layer 18 is provided. Lower electrode layer 17
In the present embodiment, is a metal thin film formed so as to be embedded in the substrate 10, and has a window 17A for transmitting ultraviolet light. The upper electrode layer 18 is the second
Is a metal thin film formed so as to cover the layer 16 of the above, and a window 18A for transmitting ultraviolet light is provided at a position corresponding to the window 17A of the lower electrode layer 17. Lower electrode layer 1
7 and the upper electrode layer 18 include aluminum (Al), gold (Au), chromium (Cr), titanium (T).
i) are mentioned.

Such an optical multilayer structure 1 can be manufactured by the manufacturing process shown in FIGS. 4 to 15, a case will be described in which three optical multilayer structures 1 are arranged on a substrate 10 in one direction to be manufactured. In addition, in FIG. 4 to FIG.
For simplicity, first layer 15 and second layer 16 are shown as a single layer.

First, as shown in FIG. 4, a substrate 10 made of glass, which is transparent to ultraviolet light, is prepared.
Then, as shown in FIG. 5, the groove 1 for burying the lower electrode layer 17 in the substrate 10 by the ion beam is formed.
Process 0A. The processing depth of the groove 10A can be set to, for example, 1 μm in consideration of electric resistance and the like. Island 10B
Window 1 for transmitting ultraviolet light in the lower electrode layer 17
7A.

A lower electrode layer 17 made of, for example, chromium is formed on the substrate 10 in which the groove 10A has been processed. The film-forming thickness at this time is equal to or more than the processing depth (1 μm in the present embodiment) of the groove 10A shown in FIG. After that, as shown in FIG. 6, the lower electrode layer 17 and the substrate 10 are flattened so that the surfaces thereof are flush with each other. As a result, the lower electrode layer 17 having the window 17A for transmitting ultraviolet light is formed in a state of being embedded in the substrate 10.

After forming the lower electrode layer 17, the low refractive index layers 12A to 12D made of magnesium fluoride and the high refractive index layers 13A to 13D made of antimony oxide are alternately laminated in the thickness shown in Table 1. Then, as shown in FIG. 7, the first layer 1 is patterned by etching into a predetermined shape.
5 is formed. The etching at this time is, for example, RIE.
(Reactive Ion Etching).

Further, an amorphous silicon (a-Si) layer 19 is formed as a sacrificial layer for forming the gap portion 14. The film thickness of the amorphous silicon layer 19 formed at this time is the optical size of the gap portion 14 (in the present embodiment,
As shown in Table 1, it is 189.3 nm). After that, as shown in FIG. 8, the amorphous silicon layer 19 is patterned into a predetermined shape by etching. Etching at this time is also performed by, for example, RIE (Reactive Ion Etc
hing).

Successively, high refractive index layers 13E to 13H made of antimony oxide and low refractive index layers 12F to 12H made of magnesium fluoride were alternately laminated to have the film thickness shown in Table 1 and shown in FIG. As described above, the second layer 16 is formed by patterning into a predetermined shape by etching. The etching at this time is, for example, RIE (Reactive Ion Etchi
ng). The reference numeral 20 indicates an opening for forming a spacer 21 described later.

After forming the second layer 16, an upper electrode layer 18 made of aluminum is formed and patterned into a predetermined shape as shown in FIG. 10 to form a window 18A for transmitting ultraviolet light. To do.

Next, a silicon dioxide (SiO ₂ ) film is measured as 2 μm from the surface of the substrate 10 as a spacer 21 to be inserted between the optical multilayer structure 1 and a cover glass described later.
1 is formed by a lift-off method so as to have a thickness of m.
1 and patterning into a predetermined shape as shown in FIG.

Finally, the amorphous silicon layer 19 is removed by dry etching using Zenon difluoride (XeF ₂ ) to form the gap portion 14 as shown in FIGS. 13 to 15. As a result, the optical multilayer structure 1 shown in FIG. 1 is completed. In addition, the dimension in the planar shape in a state where three optical multilayer structures 1 as shown in FIG. 13 are arranged in one direction is, for example, 5 inches SVGA, 800 ×
In the case of a 600-pixel direct-view / reflection-type image display device, the size is 147 μm in length × 147 μm in width.

The optical multilayer structure 1 having the above structure is driven by the electrostatic force generated by applying the voltage to the lower electrode layer 17 and the upper electrode layer 18. That is,
Due to the electrostatic attraction generated by the potential difference due to the voltage application between the upper electrode layer 18 and the lower electrode layer 17, the optical size of the gap portion 14 is set to an odd multiple of λ / 2 and an even number of λ / 2. It is binary-switched between double (including 0) (for example, between “λ / 2” and “0”), thereby changing the amount of reflection or transmission of incident ultraviolet light. Of course, by continuously changing the voltage applied to the upper electrode layer 18 and the lower electrode layer 17, the size of the gap portion 14 is continuously changed within a certain value range, and the incident ultraviolet light is reflected or transmitted. It is also possible to change the amount of A in a continuous (analog) manner.

Here, it is assumed that the optical size of the gap portion 14 is binary-switched between, for example, "λ / 2" and "0". When the potential difference between the upper electrode layer 18 and the lower electrode layer 17 is 0 V, as shown in FIG.
Layer 16 is separated from the first layer 15,
The optical size of the gap portion 14 is “λ / 2”. At this time, the ultraviolet light UV1 incident from the back surface of the substrate 10 cannot be transmitted.

On the other hand, when a positive voltage (for example, + 10V in this embodiment) is applied to the upper electrode layer 18 and the lower electrode layer 17 is grounded to 0V, an electrostatic attractive force is generated.
Due to this electrostatic attraction, as shown in FIG. 2, the second layer 1
6 adheres to the first layer 15. In this way, the optical size of the gap portion 14 becomes "0". At this time, the ultraviolet light UV1 incident from the back surface of the substrate 10 can pass through the windows 17A and 18A and pass through the substrate 10, the first layer 15, and the second layer 16 (UV2 in FIG. 2).

[Optical Switching Device] FIGS. 16 and 1
7 shows a configuration of an optical switching device 30 using the optical multilayer structure 1. The optical switching device 30 is specifically used as a direct-view / transmissive image display device that displays an image by switching ultraviolet light.

The optical switching device 30 includes the common substrate 3
A plurality of (12 in the figure) optical switching elements 3
0A to 30L are arranged in a two-dimensional array.
In FIG. 15, only the optical switching elements 30A to 30C are completely shown. The configuration is not limited to two dimensions, and may be one-dimensionally arranged. Optical switching element 30A
Since each of 30L to 30L has the same configuration as the optical multilayer structure 1 of the above-described embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted. Further, as the substrate 31, the same substrate as the substrate 10 in the above-described embodiment can be used.

In FIG. 16, each optical switching element 3
A common cover glass 32 is joined to the spacers 21 of 0A to 30L. The inside is sealed in a nitrogen (N ₂ ) or helium (He) atmosphere. The internal pressure is
The helium atmosphere is determined to be 0.5 KPa, for example, in this embodiment. Since the optical switching device 30 is used as an image display device, inside the cover glass 32, phosphors 33 of red (R), green (G), and blue (B) colors are provided.
R, 33G and 33B are patterned. As the phosphors 33R, 33G, 33B, those excited by ultraviolet light are used.

Optical switching elements 30A-3 on the substrate 31
An ultraviolet light source 34 is provided on the side opposite to 0L. Further, a microlens array 35 for enhancing the utilization efficiency of ultraviolet light is bonded to the back surface of the substrate 31. In the optical switching elements 30A to 30L, the ultraviolet light is blocked by the lower electrode layer 17 and can only pass through the windows 17A and 18A, but by providing the microlens array 35, the utilization efficiency of the ultraviolet light can be improved. . In addition,
In FIG. 17, the ultraviolet light source 34 is not shown.

As can be seen from FIG. 16 or FIG. 17, in this optical switching device 30, the optical switching elements 30A and 30C are in the low transmission (high reflection) state, and the optical switching element 30B is in the high transmission (low reflection) state. Has become. Therefore, as shown in FIG. 17, the ultraviolet light UVA, UV that has entered the optical switching elements 30A, 30C.
C cannot pass through the optical switching element 30.
A and 30C are dark areas on the screen. On the other hand, in the optical switching element 30B, the ultraviolet light UVB1 is transmitted and UV
It becomes B2, and further passes through the phosphor 33G and the cover glass 32 to become UVB3, which becomes a bright portion on the screen.

[Image Display Device] The optical switching device 30 shown in FIGS. 16 and 17 is, for example, a PDA (Person).
al Digital Assistant) or a direct-view image display device such as a computer monitor can be directly applied.

As described above, according to the optical multilayer structure 1 of the present embodiment, the low refractive index layer 1 is formed on the substrate 10.
2A to 12H and high refractive index layers 13A to 13H are alternately laminated to produce an optical multilayer film structure 11, and a low refractive index layer 12E is manufactured.
Since the gap is used as the gap portion 14, excellent optical characteristics can be exhibited. Furthermore, since the three optical multilayer structures 1 form one pixel on the screen, the structure is simpler and the size is smaller than that of a GLV that requires six grid ribbons for one pixel, for example. can do. Therefore, when applied to an image display device, the size and weight can be reduced, and the response speed is increased due to the small size. Therefore, improvement in the quality of moving image display with fast movement can be expected.

In this embodiment, the low refractive index layers 12A to 12H other than the low refractive index layer 12E (that is, the gap portion 14) are made of magnesium fluoride, and the high refractive index layers 13A to 13H are made of antimony oxide. The optical characteristics of

Further, the lower electrode layer 1 made of a metal thin film is used as a driving means for switching the optical size of the gap portion 14.
7 and the upper electrode layer 18, and further the lower electrode layer 17
And a window 1 for transmitting ultraviolet rays to the upper electrode layer 18.
Since 7A and 18A are formed, the optical multilayer structure 1 can be driven by electrostatic force to switch ultraviolet light. At present, there is no material that is transparent (does not absorb) to ultraviolet light and has conductivity, but in the optical multilayer structure 1 according to the present embodiment, the low refractive index layer 12A is used.
.About.12H and high refractive index layers 13A to 13H are transparent to ultraviolet light, and a conductive metal thin film is used as the lower electrode layer 17 and the upper electrode layer 18, and the windows 17A, 1
Ultraviolet light can be transmitted through 8A. Further, in the optical multilayer structure 1, the second movable part
Since the layer 16 and the upper electrode layer 18 can be made smaller and lighter, high speed switching becomes possible.

According to the optical switching device 30 of this embodiment, since the optical multilayer structure 1 of this embodiment is used as each of the optical switching elements 30A to 30L, high-speed switching of ultraviolet light is possible, And desired optical characteristics can be obtained.

The optical switching device 30 can be applied to various image display devices in combination with the phosphors 33R, 33G, 33B excited by ultraviolet light, the microlens array 35, and the like. Since the image display device using the optical switching device 30 does not need a polarizing plate, a direct-view full-color image display device with high light utilization efficiency can be realized.
Further, since the phosphor is excited by using ultraviolet light as a light source, it is a self-luminous image display device like the cathode ray tube, and can display a much brighter image than an image display device using liquid crystal.

Furthermore, since the optical multilayer structure 1 is small and lightweight and capable of high-speed switching, the image display device using the optical switching device 30 is suitable for use in portable information equipment and the like, and is fast-moving. It can also support video display.

Since the optical switching elements 30A to 30L of the optical switching device 30 are voltage control elements using the optical multi-layer structure 1 driven by electrostatic force,
When the optical switching device 30 is used as a direct-view / transmissive image display device, the power consumption becomes very small.

In addition, in the present embodiment, if a plurality of optical multilayer structures 1 are assigned to one pixel, they can be driven independently of each other. Therefore, when performing gradation display of image display as an image display device. Not only the method of time division but also gradation display by area is possible.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made. For example, in the above embodiment, the groove 10 for embedding the lower electrode layer 17 in the substrate 10 is used.
Although A was processed by the ion beam, it is also possible to process it by wet etching, RIE or the like.

Further, the film thickness of each layer of the optical multilayer structure 1 shown in Table 1 is designed to be optimum for ultraviolet light having a wavelength of 300 nm. However, since the wavelengths that can be excited most efficiently differ depending on the phosphors 33R, 33G, 33B used, it is necessary to make an optimum design according to the wavelengths. Therefore, the film thickness of each layer of the optical multilayer structure 1 does not necessarily have to be as shown in Table 1.

In addition, in the optical switching device 30 shown in FIGS. 16 and 17 or the image display device using the same, a color filter is further combined between the substrate 31 and the microlens array 35, so that the ultraviolet light Utilization efficiency can be further improved.

In the above-mentioned embodiment, the dimension in the plane shape when the three optical multilayer structures 1 as shown in FIG. 13 are arranged in one direction is, for example, 5 inches SVGA, 8
In the case of a direct view / reflective image display device of 00 × 600 pixels, the size is set to 147 μm in length × 147 μm in width. However, by reducing the size of the optical multilayer structure 1 to several μm, a head mounted display, It can also be applied to face mount displays. As described above, by simply changing the dimensions of the optical multilayer structure 1, a face-mounted display to a large direct-view image display device can be realized with basically the same configuration.

Furthermore, in the above embodiment, an example in which the optical switching device 30 is used in a direct-view / transmissive image display device has been described, but the invention is not limited to the direct-view / transmissive image display device.
Application to other image display devices such as a projection type is also possible. Further, it can be applied to various devices such as an optical printer other than the image display device, for example, an image can be drawn on a photosensitive drum using the optical printer.

[0064]

As described above, according to the optical multilayer structure of any one of claims 1 to 4,
Since an optical multilayer film structure in which low refractive index layers and high refractive index layers are alternately laminated is formed, and one of the low refractive index layers is replaced with a gap portion, excellent optical characteristics can be obtained. At the same time, the size and weight can be reduced, and the response speed can be improved.

In particular, according to the optical multilayer structure of the second aspect, the low refractive index layer other than the gap portion is made of magnesium fluoride,
Since the high refractive index layer is made of antimony oxide, desired optical characteristics can be obtained.

Further, in particular, according to the optical multilayer structure of the third or fourth aspect, a window for transmitting ultraviolet rays is formed as a driving means for switching the optical size of the gap portion. Since the lower electrode layer and the upper electrode layer made of a metal thin film are provided, the optical multilayer structure can be driven by electrostatic force to switch ultraviolet light. Since this optical multilayer structure is a voltage-controlled element, it consumes very little power when used in an image display device.

According to the optical switching element of the fifth aspect, since the optical multilayer structure of the present invention is used, the optical switching element is small and lightweight, and the switching operation is speeded up. This optical switching element is therefore most suitable for use in image display devices such as portable information devices.

According to the image display device of the sixth or seventh aspect, since the optical multilayer structure or the optical switching element of the present invention is used, the image display device is most suitable for applications such as portable information equipment which is required to be small and lightweight. . Also, since the response speed becomes faster, it is expected that the quality of moving image display with fast movement will be improved. Since this image display device does not require a polarizing plate, a direct-view type full-color image display device having high light utilization efficiency can be realized. Also, since it is a structure that excites the phosphor using ultraviolet light as a light source, it is a self-luminous image display device similar to a cathode ray tube.
It is possible to display a much brighter image than an image display device using a liquid crystal.

Particularly, according to the image display device of the seventh aspect, since the microlens is further provided, there is an effect that the utilization efficiency of light can be significantly increased.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration when an optical size of a gap portion of an optical multi-layer structure according to an embodiment of the present invention is “λ / 2”.

FIG. 2 is a cross-sectional view showing a configuration when the optical size of a gap portion of the optical multilayer structure shown in FIG. 1 is “0”.

FIG. 3 is a characteristic diagram showing transmission characteristics of the optical multilayer structure shown in FIG.

FIG. 4 is a perspective view for explaining a manufacturing process of the optical multilayer structure shown in FIG.

5 is a perspective view for explaining a step that follows the step of FIG.

FIG. 6 is a perspective view for explaining a step that follows the step of FIG.

FIG. 7 is a perspective view for explaining a step that follows the step of FIG.

FIG. 8 is a perspective view for explaining a step that follows the step of FIG.

9 is a perspective view for explaining a step that follows the step of FIG.

FIG. 10 is a perspective view for explaining a step that follows the step of FIG.

FIG. 11 is a perspective view for explaining a step that follows the step of FIG.

12 is a cross-sectional view taken along line XII-XII of FIG.

FIG. 13 is a perspective view for explaining a step that follows the step of FIG.

14 is a sectional view taken along line XIV-XIV in FIG.

15 is a sectional view taken along line XV-XV in FIG.

FIG. 16 is a perspective view showing a schematic configuration of an optical switching device applicable to the image display device according to the present embodiment.

17 is a sectional view taken along line XVII-XVII in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical multilayer structure, 10 ... Substrate, 11 ... Optical multilayer structure, 12A-12H ... Low refractive index layer, 13A-13H ... High refractive index layer, 14 ... Gap part, 15 ... 1st layer, 16 ... Second
Layer, 17 ... lower electrode layer, 18 ... upper electrode layer, 17A,
18A ... Window, 30 ... Optical switching device, 30A-30
C ... Optical switching element, 31 ... Substrate, 32 ... Cover glass, 33R, 33G, 33B ... Phosphor, 34 ... Ultraviolet light source, 35 ... Microlens array

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H041 AA16 AB14 AB40 AC06 AZ02                       AZ05 AZ08                 2H048 GA04 GA13 GA23 GA43 GA60                       GA61                 2H049 AA07 AA33 AA37 AA51 AA60                       AA68

Claims (7)

[Claims] 1. A low refractive index layer included in an optical multilayer film structure comprising a substrate transparent to ultraviolet light, and a low refractive index layer and a high refractive index layer alternately laminated on the substrate. A gap portion having a size capable of causing a light interference phenomenon and having a variable size, and the low refractive index layer and the high refractive index layer laminated on the substrate side with respect to the gap portion. And a second layer composed of the low-refractive index layer and the high-refractive index layer, which are laminated on the opposite side of the substrate with respect to the gap portion. . 2. The substrate is made of glass,
The low-refractive index layers other than the low-refractive index layer corresponding to the gap are made of magnesium fluoride (MgF ₂ ), and the high-refractive index layer is made of antimony oxide (Sb ₂ O ₃ ). The optical multilayer structure according to claim 1, wherein: 3. A driving means for changing the optical size of the gap portion is provided between the first layer and the substrate, and
A lower electrode layer, which is a metal thin film having a window for transmitting ultraviolet light, and a metal provided with a window for transmitting ultraviolet light, which is provided on the opposite side of the second layer from the substrate. 2. An optical element according to claim 1, further comprising an upper electrode layer which is a thin film, wherein the amount of reflection or transmission of incident light is changed by changing the size of the gap portion by the driving means. Multi-layer structure. 4. The upper electrode layer and the lower electrode layer are made of aluminum (Al), gold (Au), chromium (C).
The optical multilayer structure according to claim 3, wherein the optical multilayer structure is composed of r) and titanium (Ti). 5. A low-refractive index layer included in an optical multilayer film structure comprising a substrate transparent to ultraviolet light, and low-refractive index layers and high-refractive index layers alternately laminated on the substrate. A gap having a size capable of causing a light interference phenomenon and having a variable size, and the low refractive index layer and the high refractive index layer laminated on the substrate side with respect to the gap. An optical multi-layer structure having a first layer formed by: and a second layer formed by stacking the low refractive index layer and the high refractive index layer on the opposite side of the substrate with respect to the gap, and the gap An optical switching element comprising: a driving unit for changing the optical size of the optical switching element. 6. A plurality of one-dimensionally or two-dimensionally arranged optical switching elements, an ultraviolet light source, and a phosphor, wherein the plurality of optical switching elements are irradiated with ultraviolet light from the ultraviolet light source. An image display device for displaying a two-dimensional image by exciting a phosphor, wherein the optical switching element includes a substrate transparent to ultraviolet light, and a low refractive index layer and a high refractive index layer on the substrate. Formed as one of the low-refractive-index layers included in the optical multilayer film structure in which the layers are alternately laminated, and having a size capable of causing a light interference phenomenon and having a variable size; A first layer composed of the low-refractive index layer and the high-refractive index layer laminated on the substrate side, with respect to the gap, the low-refractive index layer and the high-refractive index layer laminated on the opposite side of the substrate. And a second layer consisting of The image display apparatus comprising: the optical multilayer structure, and drive means for changing the optical size of the gap portion. 7. The microlens is further provided between the substrate and the ultraviolet light source.
The image display device described.