JPH11258558A - Planar display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat surface display device wherein it has a good luminous utilization efficiency, a high degree of vacuum is not required, permitting to enlarge a screen area at an inexpensive cost, and moreover, a high quality image is obtained. SOLUTION: A linear or quadratic matrix form light modulating part 14 modulating light from a flat surface light source by an electro-mechanical operation is arranged on a flat surface light source of ultraviolet rays. The phosphors 16a, 16b, 16c excited by the light coming out of this light modulating part 14 are arranged to be opposed to the light modulating part 14. Moreover, the light modulating part 14 is provided with a transparent signal electrode 3 which is one electrode arranged on a light guide plate, a transparent flexible thin film 9 opposed to this signal electrode 3 across an air gap 11, and a scanning electrode 13 which is the other electrode opposed to the signal electrode 3 arranged on the flexible thin film 9, and bends the flexible thin film 9 by a Coulomb force generated by impressing an electric field across the signal electrode 3 and the scanning electrode 13, and modulates the light transmitting the flexible thin film 9 and emitted therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel display for exciting a phosphor by modulating light from a flat light source.

[0002]

2. Description of the Related Art Conventionally, various types of thin flat display devices have been proposed, and typical ones include, for example, a liquid crystal display device, a plasma display device, and a field emission display (FED).

[0003] A liquid crystal display device encloses and seals a nematic liquid crystal between a substrate on which a pair of conductive transparent films are formed and oriented so as to be parallel to the substrate and twisted by 90 ° between the two substrates. It has a structure in which this is sandwiched between orthogonal polarizing plates. The display by this liquid crystal display device utilizes the fact that by applying a voltage to the conductive transparent film, the major axis direction of the liquid crystal molecules is oriented perpendicular to the substrate and the transmittance of light from the backlight changes. It is done. An active matrix liquid crystal panel using a TFT (thin film transistor) is used to provide high image quality display and moving image correspondence.

[0004] In a plasma display device, a large number of regularly arranged orthogonal electrodes corresponding to an anode and a cathode are arranged between two glass plates filled with a rare gas such as neon, and an intersection of each opposing electrode. Is a unit pixel.
The display by the plasma display device is based on image information, by selectively applying a voltage to the opposing electrodes for specifying the respective intersections, thereby causing the intersections to discharge and emit light, and exciting the phosphor by the generated ultraviolet light. This is performed by emitting light.

[0005] The FED has a structure as a flat display tube in which a pair of panels are arranged to face each other with a minute space therebetween, and the periphery of these panels is sealed. A fluorescent film is provided on the inner surface of the panel on the display surface side, and field emission cathodes are arranged on the back panel for each unit light emitting region. A typical structure of a field emission cathode has a field emission type microcathode having a conical projection shape called an emitter tip having a small size. The display by the FED is performed by extracting electrons using an emitter tip and irradiating the electrons with the accelerated phosphor to excite the phosphor.

[0006]

However, the above-described conventional flat panel display has the following various problems. That is, in the liquid crystal display device, since light from the backlight is transmitted through a plurality of layers of the polarizing plate, the transparent electrode, and the color filter, there is a problem that light use efficiency is reduced.
In addition, the high-quality type has a drawback that a TFT is required, and liquid crystal must be injected between two substrates and aligned, which makes it difficult to increase the area. Furthermore,
Since light is transmitted through the aligned liquid crystal molecules, the viewing angle is disadvantageously narrow.

[0007] The plasma display device requires the formation of partition walls for generating plasma for each pixel and a high degree of vacuum sealing, resulting in high manufacturing cost and heavy weight. Further, since a large number of electrodes corresponding to the anode and the cathode must be regularly arranged for each unit pixel, the number of electrodes is increased, and it is difficult to obtain a high-definition and high-brightness image. Further, there is a disadvantage that the driving voltage is high and the driving IC is expensive.

In the FED, it is necessary to make the inside of the panel a high vacuum in order to make the discharge highly efficient and stable, and there is a drawback that the manufacturing cost becomes high similarly to the plasma display device. In addition, since the field-emitted electrons are accelerated to irradiate the phosphor, a high voltage is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has good light utilization efficiency, does not require a high vacuum, can have a large area at low cost, and can obtain high image quality. It is an object of the present invention to provide a flat display device having a low driving voltage.

[0010]

According to a first aspect of the present invention, there is provided a flat panel display device according to the present invention, wherein a light from the flat light source is modulated on a flat ultraviolet light source by electromechanical operation. A one-dimensional or two-dimensional matrix light modulating section is provided, and a phosphor excited by light emitted from the light modulating section is arranged to face the light modulating section.

In this flat display device, the intensity of the light emitted from the light modulator is controlled by operating the light modulator by electromechanical operation, for example, utilizing Fabry-Perot interference.
As a result, the phosphor can be excited to obtain an image by fluorescence emission.

According to a second aspect of the present invention, in the flat display device, the light modulating portion has one electrode formed on the flat light source or on a substrate disposed between the flat light source and the phosphor, and at least a gap is formed in the one electrode. The other electrode sandwiched and opposed to the electrode includes a flexible thin film that is interposed between the one electrode and the other electrode and is transparent to the ultraviolet light. The method is characterized in that the flexible thin film is bent by a Coulomb force generated by applying an electric field, and light transmitted through the flexible thin film and modulated.

In this flat display device, one electrode and the flexible thin film on which the other electrode is formed are opposed to each other with a gap therebetween, and the flexible thin film can be operated by electromechanical operation. A flat display device can be configured. In addition, since light from the flat light source only passes through the pair of transparent electrodes sandwiching the gap, the light use efficiency is increased.

According to a third aspect of the present invention, in the flat panel display device, the one of the plurality of parallel electrodes formed in a band shape is juxtaposed on the flat light source or on a substrate disposed between the flat light source and the phosphor. By arranging a plurality of the other parallel electrodes formed in a band shape on the flexible thin film in a direction orthogonal to the one electrode, the one electrode and the other electrode are arranged to face each other in a lattice shape. It is characterized by.

In this flat panel display, a plurality of strip-shaped parallel signal electrodes and scanning electrodes are arranged in a grid pattern in an orthogonal direction, and the phosphor can be excited by digital multi-exposure.

According to a fourth aspect of the present invention, there is provided a flat display device, wherein an active element for electrically switching is provided for each pixel, the one electrode is connected to a drain (or source) of the active element, and the other electrode is connected to a common electrode. , The image signal line of each column is connected to the source (or drain) of the active element, the scanning signal line of each row is connected to the gate of the active element, and the active element is scanned row by row, An image signal is applied to the one electrode to perform light modulation by active matrix driving.

In this flat display device, a voltage for conducting the active element is applied to the scanning signal line connected to the gate of the active element, and a desired image signal voltage is applied to the image signal line connected to the drain. Then, the drain and the source conduct, and the image signal voltage is applied to the pixel electrode. Thereby, an electrostatic stress acts by the voltage between the potential of the common electrode and the potential of the pixel electrode, and desired light modulation can be performed.

According to a fifth aspect of the present invention, in the flat panel display device, the flat light source is constituted by an ultraviolet lamp and a light guide plate, and an electric field is applied to the one electrode and the other electrode so that the flexible thin film is formed on the light guide plate. By contacting or sufficiently approaching, the ultraviolet light guided to the light guide plate is transmitted to the flexible thin film side.
It is characterized by emitting light and performing light modulation.

In this flat panel display device, when the voltage between the electrodes is zero and there is a gap between the flexible thin film and the light guide plate, the ultraviolet light travels while totally reflecting inside the light guide plate. On the other hand, when a voltage is applied between the two electrodes and the flexible thin film and the light guide plate are in contact with each other or are sufficiently close to each other, the ultraviolet light propagates and transmits to the flexible thin film side and is emitted to the surface side of the flexible thin film. Therefore, light modulation can be performed by controlling the position of the flexible thin film by applying a voltage.

According to a sixth aspect of the present invention, in the flat display device, the flexible thin film has a function of emitting light transmitted from the light guide plate by diffusion or scattering.

In this flat panel display device, when the flexible thin film and the light guide plate come into contact with each other or come sufficiently close to each other, ultraviolet rays are diffused by the light diffusing action of the flexible thin film and emitted to the surface side.

The flat display device according to claim 7, wherein an electric field is applied to the one electrode and the other electrode, and the flexible thin film bends to generate an optical multi-layer interference effect so that the ultraviolet light is emitted. Is performed.

In this flat display device, when no voltage is applied between the electrodes, a gap remains formed between the light guide plate and the flexible thin film, the light intensity transmittance is suppressed low, and Is hardly transmitted. On the other hand, when a voltage is applied between the electrodes, the gap between the light guide plate and the flexible thin film is shortened, the light intensity transmittance is increased, and ultraviolet light is transmitted. As a result, light modulation becomes possible.

The flat display device according to claim 8, wherein the flexible thin film having a light intensity reflectance with respect to the ultraviolet light, and a film disposed opposite to the flexible thin film and having a light intensity reflectance with respect to the ultraviolet light. Wherein the optical length of the two films is changed by bending the flexible thin film to generate an optical multilayer film interference effect, thereby performing the light modulation of the ultraviolet light.

In this flat panel display device, when no voltage is applied between the electrodes, the optical lengths of the two films having the light intensity reflectivity arranged opposite to each other do not change. On the other hand, when a voltage is applied between the electrodes, the flexible thin film bends to change the optical length of the two films, thereby causing an optical multilayer film interference effect. As a result, light modulation becomes possible.

According to a ninth aspect of the present invention, in the flat display device, an electric field is applied to the one electrode and the other electrode, and the flexible thin film bends to change the path of the ultraviolet light to modulate the light of the ultraviolet light. It is characterized by performing.

In this flat display device, when no voltage is applied between the electrodes, the flexible thin film absorbs or reflects ultraviolet light to block the path. On the other hand, when a voltage is applied between the electrodes,
By bending the flexible thin film, it deviates from the path of ultraviolet rays,
Ultraviolet light can be transmitted forward. As a result, light modulation becomes possible.

According to a tenth aspect of the present invention, in the flat panel display, a film that transmits the ultraviolet light and reflects the visible light is disposed between the light modulation unit and the phosphor unit.

In this flat display device, the fluorescent material is irradiated with ultraviolet rays, and visible light is scattered and emitted. Of the visible light, the light scattered toward the light modulator is reflected toward the surface by the film that reflects the visible light, thereby increasing the display efficiency.

The flat display device according to an eleventh aspect is characterized in that a film that absorbs or reflects the ultraviolet light and transmits visible light is disposed on the emission surface side of the phosphor portion.

In this flat panel display, the ultraviolet light to be emitted is absorbed or reflected on the emission surface side of the phosphor by the film that absorbs or reflects the ultraviolet light. As a result, no ultraviolet light is emitted from the display surface. In addition, since the ultraviolet light is reflected on the emission surface side of the phosphor portion, the ultraviolet light can be reused, and the display efficiency is increased.

In a twelfth aspect of the present invention, the flat panel light source is characterized in that the ultraviolet light of the flat light source is collimated light.

In this flat display device, since the ultraviolet light of the flat light source is converted into collimated light, it is possible to emit ultraviolet light having directivity.

According to a thirteenth aspect of the present invention, in the flat display device, the flat light source is a low-pressure mercury lamp as a light source, and the ultraviolet light is 254.
The wavelength is centered on nm.

In this flat display device, a line spectrum of 254 nm is a main component, and since it is a line spectrum, it has a very high energy transmittance, and can perform modulation with high efficiency and high contrast.

According to a fourteenth aspect of the present invention, in the flat display device, the flat light source is a low-pressure mercury lamp coated with a phosphor that emits ultraviolet light, and the ultraviolet light has a wavelength of 300 nm to 400 nm.
Is characterized by having a wavelength around.

In this flat panel display, ultraviolet light having a specific wavelength is used as backlight light. Therefore, by setting the light intensity reflectance of the dielectric multilayer mirror when a voltage is applied between the electrodes and when not applying the voltage, the voltage is set when the voltage is applied by setting the reflectance in correspondence to the ultraviolet light of a specific wavelength. In this case, only ultraviolet rays having a specific wavelength can be transmitted. As a result, light modulation becomes possible. Further, it is not necessary to use an expensive optical substrate such as quartz glass.

According to a fifteenth aspect of the present invention, in the flat panel display device, the flat light source is a light emitting element that emits ultraviolet light.

In this surface display device, the size of the light source itself can be reduced by using a light emitting element as the light source.

According to a sixteenth aspect of the present invention, in the flat display device, the amount of light transmitted through the light modulator is arbitrarily controlled by continuously changing the flexible thin film depending on the intensity of the electric field.

In this flat panel display, the amount of transmitted light is continuously controlled, and gradation control can be performed by controlling the applied voltage.

[0042]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the flat panel display according to the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a cross-sectional view of the first embodiment of the flat panel display according to the present invention, and FIG. 2 is a view taken along the line AA of FIG.

A plurality of strip-shaped transparent electrodes (signal electrodes) 3 are arranged in parallel on the light guide plate 1 at intervals. On the light guide plate 1, there are formed columns 5 that partition adjacent signal electrodes 3 from each other. The support 5 can be formed by, for example, etching the same material as the light guide plate 1. An ultraviolet lamp (low-pressure mercury lamp) 7 serving as a light source is provided on a side surface of the light guide plate 1, and light from the low-pressure mercury lamp 1 is guided to the surface of the light guide plate 1 (upper surface in FIG. 1).

A transparent flexible thin film 9 is formed on the upper end surface of the support 5 at a position away from the signal electrode 3. Therefore, a gap 11 is formed between the signal electrode 3 and the flexible thin film 9. On the upper surface of the flexible thin film 9, another transparent strip-shaped electrode (scanning electrode) 13 which is long in a direction orthogonal to the signal electrode 3.
Are arranged in parallel at intervals. That is, as shown in FIG. 2, the signal electrodes 3 and the scanning electrodes 13 are arranged in a grid arranged in a direction orthogonal to each other. The signal electrode 3 and the scanning electrode 13 are matrix electrodes that can specify a specific counter electrode portion by selecting a predetermined one. The light guide plate 1, the signal electrode 3, the flexible thin film 9, and the scanning electrode 13 constitute a light modulator 14.

A power supply 15 is connected to each of the signal electrodes 3 and the scanning electrodes 13, and the power supply 15 can selectively apply a voltage to a predetermined one based on image information.

Further, above the scanning electrodes 13, strip-shaped phosphors 16a, 16b, 16c of three primary colors (R, G, B) are provided.
Is provided so as to face the signal electrode 3. This phosphor 1
A black matrix (not shown) for improving the contrast ratio of the phosphor may be disposed between 6a, 16b, and 16c.

A transparent front plate 17 is provided above the phosphors 16a, 16b, 16c. Also, the front plate 17
May be provided with a color filter equivalent to the phosphor emission color.

The flat display device 19 thus configured
The light guide plate 1 can be formed of a transparent glass plate or a resin film such as polyethylene terephthalate or polycarbonate.

The signal electrode 3 and the scanning electrode 13 are made of a transparent conductive material. The signal electrode 3 arranged on the light guide plate 1 side is preferably made of a material that transmits ultraviolet light for excitation or has optical characteristics. Further, the phosphor 16a,
It is preferable that the scanning electrodes 13 disposed on the 16b and 16c sides transmit a UV ray for excitation and more preferably have a material or an optical property that reflects a phosphor emission wavelength.

This transparent electrode is generally made of a metal made transparent by fine particles or a metal compound having conductivity. As the metal, gold, silver, palladium, zinc, aluminum, or the like can be used. As the metal compound, indium oxide, zinc oxide, aluminum-added zinc oxide (commonly known as AZO), or the like can be used. Specifically, a SnO2 film (Nesa film), an ITO film, and the like can be given.

The signal electrode 3 and the scanning electrode 13 are formed by laminating a thin film of the above-described conductive material on the surface of the light guide plate 1 or the flexible thin film 9 by a sputtering method or a vacuum evaporation method, and applying a resist on the surface of the thin film. Then, it can be formed by performing exposure and development. Exposure is performed by arranging a photomask on the photoresist and irradiating ultraviolet rays from above, and development is performed by processing with a developing solution capable of removing a soluble portion of the photoresist.

FIG. 3 is a sectional view showing the state of the flat display device according to the present invention during operation. In the flat panel display 19, when a voltage is applied between the signal electrode 3 and the scanning electrode 13 by the power supply 15, the flexible thin film 9 is sucked by the Coulomb force and bends toward the gap 11. The bending operation of the flexible thin film 9 due to the Coulomb force is hereinafter referred to as an electromechanical operation. Thus, the light transmitted from the light guide plate 1 and emitted through the flexible thin film 9 is modulated. Therefore, by selectively applying the voltage of the power supply 15 to each of the signal electrodes 3 and the scanning electrodes 13 based on the image information, desired exposure control becomes possible, and the light whose exposure has been controlled is emitted from the phosphors 16a and 16b. ,
16c will be excited to form an image.

As described above, according to the above-described flat display device 19, the light from the light guide plate 1 only excites the phosphors 16a, 16b, and 16c by transmitting through the pair of transparent electrodes sandwiching the gap 11. Light use efficiency can be improved.
Further, the viewing angle can be made wider than that of a liquid crystal display device that transmits light by exciting liquid crystal molecules.

Since the light from the light guide plate 1 is modulated by the electromechanical operation of the flexible thin film 9, the image quality depends on the regular arrangement of a large number of electrodes as in the case of a plasma display device. And high image quality can be easily obtained.
Further, since it is not necessary to form a partition for generating plasma for each pixel as in the case of a plasma display device and to increase the vacuum, the weight and area can be easily reduced, and the manufacturing cost can be reduced.

Further, since the light guide plate 1, the signal electrode 3, the support 5 and the like can be arrayed by etching, the manufacturing cost can be reduced.

Furthermore, since the flexible thin film 9 can be driven by the electromechanical operation of bending the film by Coulomb force, the plasma display device generates plasma, or the FED accelerates the field-emitted electrons to irradiate the phosphor. The driving voltage can be reduced.

The light modulator 14 of the flat display device 19
May be formed integrally with the light guide plate 1 as a substrate or separately formed.

The light modulator 14 of the flat panel display 19
After degassing, a rare gas may be sealed to seal the whole, and the influence of disturbance may be prevented to achieve stabilization.

Next, a second embodiment of the surface display device according to the present invention will be described. FIG. 4 is a plan view showing a light modulator of the second embodiment, FIG. 5 is a sectional view taken along line AA of FIG. 4, and FIG.
FIG. 7 is an equivalent circuit diagram of the pixel section shown in FIG.

Although the flat display device of the first embodiment described above enables simple matrix driving, the flat display device may perform active driving. That is, in the flat display device 21 according to this embodiment, an active element (for example, a TFT) 23 is provided for each pixel. TFT23
It comprises a gate electrode 25, an insulating film 27, an a-Si: H layer 29, one electrode (drain electrode) 31, and one electrode (source electrode) 33. The TFT 23 is provided on the substrate 35
Formed on top.

The pixel electrode 37 is connected to the source electrode 33 of the TFT 23. An image signal line 39 for each column is connected to the drain electrode 31. The gate electrode 25 includes
The scanning signal lines 41 for each row are connected.

The pixel electrode 37 is stacked on the flexible thin film 9 in the light modulator 43. The flexible thin film 9 is cross-linked to the pillar 5. Further, another electrode (common electrode) 47 is provided on the substrate 35 so as to face the pixel electrode 37, and the potential Vcom
Is applied.

In the light modulating section 43 of the flat display device 21 thus configured, a voltage for turning on the TFT 23 is applied to the scanning signal line 41 connected to the gate electrode 25. Then, when a desired image signal voltage is applied to the image signal line 39 connected to the drain electrode 31, the drain electrode 31 and the source electrode 33 conduct. Therefore, the image signal voltage is applied to the pixel electrode 37.
Thereby, the potential Vcom of the common electrode 47 and the pixel electrode 3
Electrostatic stress acts due to the voltage with the potential of 7, and desired light modulation can be performed.

Thereafter, the TFT 23 is scanned for scanning another row.
, The light modulation state described above is maintained, and matrix modulation of a plurality of rows becomes possible.

Next, a third embodiment of the flat panel display according to the present invention will be described. FIG. 8 is a cross-sectional view illustrating a light modulation unit of the flat display device according to the third embodiment, and FIG. 9 is a cross-sectional view illustrating an operation state of the flat display device illustrated in FIG.

The principle of operating the flexible thin film by electromechanical operation to modulate light is as follows. The light guiding diffusion action (hereinafter referred to as light guiding diffusion) by separating or contacting the flexible thin film and the transparent signal electrode. Can be used. In the light-guiding diffusion, the gap is used as a transmission resistance of light, and when the gap is formed, the light emitted from the signal electrode is blocked or attenuated, but only when the flexible thin film is brought into contact with the signal electrode, Light emitted from the signal electrode is guided (mode-coupled) to the flexible thin film, and the light is diffused in the flexible thin film to control the intensity of the light emitted from the flexible thin film (light modulation).

As shown in FIG. 8, one electrode (electrode) 51 transparent to ultraviolet rays is formed on the light guide plate 1. As this example, a metal oxide such as ITO having a high electron density, a very thin metal thin film (such as aluminum), a thin film in which metal fine particles are dispersed in a transparent insulator, or a highly doped wide hand gap semiconductor is preferable. is there.

On the electrode 51, an insulating pillar 5 is formed. For the pillar 5, for example, silicon oxide, silicon nitride, ceramic, resin, or the like can be used. A diaphragm 53 is formed on the upper end surface of the column 5. A gap (cavity) 11 is formed between the electrode 51 and the diaphragm 53. For the diaphragm 53, a semiconductor such as polysilicon, insulating silicon oxide, silicon nitride, ceramic, resin, or the like can be used. The refractive index of the diaphragm 53 is preferably equal to or higher than the refractive index of the light guide plate 1.

The light diffusion layer 5 is provided on the diaphragm 53.
5. For example, inorganic and organic transparent materials having irregularities formed on the surface, microprisms, microlenses formed, inorganic, organic porous materials, or fine particles having different refractive indices dispersed in a transparent base material And so on.

On the light diffusion layer 55, the other electrode (electrode) 57 transparent to ultraviolet rays is formed. For example, a material similar to that of the electrode 51 can be used. The diaphragm 53, the light diffusion layer 55, and the electrode 57 form a flexible thin film.

A gap 11 exists between the light guide plate 1 and the diaphragm 53, and the gap 11 is substantially determined by the height of the column 5. The height of the gap 11 is preferably, for example, about 0.1 μm to 10 μm. This gap 11 is usually formed by etching the sacrificial layer.

Further, in addition to the above configuration example, the diaphragm 53 and the light diffusion layer 55 may be formed of the same material.
For example, the diaphragm 53 is made of a silicon nitride film,
By forming unevenness on the upper surface, a diffusion function can be provided.

The operation principle of light modulation of the flat display device 61 thus configured will be described. When voltage is off, both electrodes 5
The voltage of the diaphragm 53 and the light guide plate 1 is zero.
When there is a gap 11 (eg, air) between the light guide plate 1 and the light guide plate 1, assuming that the refractive index of the light guide plate 1 is nw, the critical angle for total reflection θc at the interface with air is θc = sin ⁻¹ (nw). Therefore, when the incident angle θ to the interface is such that θ> θc
At this time, as shown in FIG. 8, the light guide plate 1 proceeds while being totally reflected.

When the voltage is ON, when a voltage is applied to both electrodes 51 and 57 to bring the diaphragm 53 and the surface of the light guide plate 1 into contact or close to a sufficient distance, as shown in FIG. To the light diffusion layer 5
5 and is emitted to the surface side.

According to the flat panel display 61 of this embodiment, light modulation can be performed by controlling the position of the diaphragm 53 by applying a voltage. Although there is an electrode 51 that is transparent to ultraviolet light between the light guide plate 1 and the diaphragm 53, the above-mentioned operation problem does not occur if the thickness of a thin film that is normally used is about 2000A. .

In the flat display device 61, the gap distance between the diaphragm 53 and the light guide plate 1 is determined by the voltage value.
The contact area can be changed. This allows control of the amount of transmitted light. By utilizing such an operation, gradation control can be performed by changing the applied voltage.

Next, a fourth embodiment of the flat panel display according to the present invention will be described. As a principle of light modulation by electromechanically operating the flexible thin film, Fabry-Perot interference can be used. In the Fabry-Perot interference, in a state where two planes are arranged in parallel to face each other, an incident light beam is divided into a number of light beams by repeating reflection and transmission, and these light beams are parallel to each other. The transmitted rays overlap and interfere at infinity. Assuming that the angle between the perpendicular of the surface and the incident light is i, the optical path difference between two adjacent light rays is x = nt ·
given by cosi. Where n is the refractive index between the two surfaces, t
Is the interval. If the optical path difference x is an integral multiple of the wavelength λ, the transmission lines strengthen each other, and if the optical path difference x is an odd multiple of a half wavelength, they cancel each other. That is, if there is no phase change at the time of reflection, the transmitted light becomes maximum when 2 nt · cosi = mλ, and becomes minimum when 2 nt · cosi = (2m + 1) λ / 2. Here, m is a positive integer.

That is, the optical path difference x becomes a predetermined value.
By moving the flexible thin film, light emitted from the signal electrode side can be modulated and emitted from the flexible thin film.

A specific example of a flat panel display utilizing such Fabry-Perot interference will be described with reference to FIGS. FIG. 10 is a plan view showing a light modulation unit of the flat panel display according to the fourth embodiment, FIG. 11 is a sectional view taken along line AA of FIG.
2 is a cross-sectional view taken along line BB of FIG. 10, FIG. 13 is a cross-sectional view illustrating an operation state of the flat panel display device illustrated in FIG. 10, FIG. 14 is an explanatory diagram illustrating spectral characteristics of a low-pressure mercury lamp for black light,
FIG. 15 is an explanatory diagram showing the light intensity transmittance of the light modulation element, and FIG.
6 is an explanatory diagram showing the spectral characteristics of the backlight by the low-pressure mercury lamp, and FIG. 17 is an explanatory diagram showing the light intensity transmittance of the light modulation element.

A dielectric multilayer mirror 73 is provided on a substrate 71 transparent to ultraviolet rays. On the substrate 71,
One pair of electrodes (electrodes) 75 is provided on both sides of the dielectric multilayer mirror 73. An electrode 75 is provided on the substrate 71.
Are provided on the left and right sides (the left and right sides in FIG. 10). A diaphragm 53 is provided on the upper end surface of the column 5. On the lower surface of the diaphragm 53 facing the dielectric multilayer mirror 73, a dielectric multilayer mirror 77 is provided. The gap 11 is formed between the dielectric multilayer mirror 73 and the dielectric multilayer mirror 77. On the surface of the diaphragm 53, a pair of other electrodes (electrodes) 79 are provided so as to face the electrodes 75. In FIG. 12, reference numeral 80 denotes a spacer.

As shown in FIG. 13, an ultraviolet lamp for black light (low-pressure mercury lamp) 83 is provided on the side surface of the plate-shaped flat light source unit 81. The flat light source unit 81 takes in ultraviolet light from the low-pressure mercury lamp 83 for black light from the side and emits it from the front side.

When a phosphor for black light (for example, BaSi ₂ O ₅ : Pb ²⁺ ) is applied to the inner wall of the low-pressure mercury lamp 83, the spectral characteristics of the emitted ultraviolet light are as shown in FIG. That is, it has a center wavelength λ ₀ near 360 nm. This ultraviolet light is used as backlight light.

In the light modulating unit 85 thus configured, the interval of the air gap 11 when the voltage is OFF is set to toff (the left state in FIG. 13). This can be controlled during device fabrication. When a voltage is applied, the gap 1
Although the interval of 1 becomes short, this is set as ton (state on the right side in FIG. 13). The control of ton can be performed by the balance between the applied electrostatic stress and the restoring force generated when the diaphragm 53 is deformed. In order to perform more stable control, the spacer 80 may be formed on the electrode so that the displacement is constant, as in this example. When this spacer is an insulator, it has the effect of reducing the applied voltage due to its relative permittivity (1 or more). In the case of conductivity, this effect is further enhanced. Further, the electrode and the spacer may be formed of the same material.

Here, ton and toff are set as follows. (M = 1). ton = 1/2 × λ ₀ = 180 nm (λ ₀ : center wavelength of ultraviolet light) ton = 3/4 × λ ₀ = 270 nm

The dielectric multilayer mirrors 73 and 77 are
The light intensity reflectance is R = 0.85. Further, the air gap 11 is made of air or a rare gas, and its refractive index is set to n = 1. Since the ultraviolet rays are collimated, the angle of incidence i that enters the light modulator 85 is substantially zero. The light modulator 85 at this time
Is as shown in FIG. Accordingly, when no voltage is applied, toff = 270 nm, and almost no ultraviolet light is transmitted. On the other hand, when voltage is applied, ton = 18
At 0 nm, ultraviolet light is transmitted.

The flat display device 9 having the light modulation section 85
According to No. 1, by bending the diaphragm 53 in this manner, a multilayer interference effect can be generated, and the light modulation of ultraviolet light can be performed.

If the condition of interference is satisfied, any combination of the interval t of the gap 11, the refractive index n, the light intensity reflectance R of the dielectric multilayer mirrors 73 and 77, etc. may be used.

When the interval t is continuously changed according to the value of the voltage, the center wavelength of the transmission spectrum can be arbitrarily changed. This makes it possible to continuously control the amount of transmitted light. That is, gradation control by an applied voltage becomes possible.

As a modified example of the light modulator 85 according to this embodiment, a backlight using a low-pressure mercury lamp can be used instead of the above-described low-pressure mercury lamp 83 for black light. That is, the direct emission spectral characteristics of the low-pressure mercury lamp mainly include a 254 nm line spectrum. A backlight unit is configured by using this lamp as a light source and combining with a light guide plate made of quartz glass or the like. Other wavelengths are cut by a filter or the like. At this time, the spectral characteristics of the ultraviolet backlight are as shown in FIG.

In the light modulation section, the constituent materials (diaphragm, dielectric multilayer mirror, substrate, etc.) of the effective pixel area are made of a material that transmits ultraviolet light of 254 nm.

Here, ton and toff are set as follows. (M = 1). ton = 1/2 × λ ₀ = 127 nm (λ ₀ : center wavelength of ultraviolet rays) ton = 3/4 × λ ₀ = 191 nm

The other conditions are the same as in the above example, and R =
0.85, n = 1, i = 0. At this time, the light intensity transmittance of the light modulation element is as shown in FIG. Accordingly, when no voltage is applied, toff = 191 nm and almost no ultraviolet light is transmitted. When a voltage is applied and ton = 127 nm, ultraviolet light is transmitted. Light modulation is thus possible.

In particular, in the case of this modified example, since the ultraviolet ray has a line spectrum, it shows a very high energy transmittance, and modulation with high efficiency and high contrast is possible.

In this modification as well, as long as the condition of interference is satisfied, any combination of the interval t of the air gap 11, the refractive index n, the light intensity reflectance R of the dielectric multilayer mirrors 73 and 77, etc. may be used.

Also in this modification, if the interval t is continuously changed according to the value of the voltage, the center wavelength of the transmission spectrum can be changed arbitrarily. This makes it possible to continuously control the amount of transmitted light.
That is, gradation control by an applied voltage becomes possible.

Next, a fifth embodiment of the flat panel display according to the present invention will be described. 18 is a perspective view showing a light modulator of the flat panel display according to the fifth embodiment, FIG. 19 is a cross-sectional view of the light modulator shown in FIG. 18, and FIG. 20 shows an operation state of the flat panel display shown in FIG. It is sectional drawing explaining.

On a substrate 101 transparent to ultraviolet light,
A transparent electrode 103 transparent to ultraviolet light is provided. The substrate 101 is shielded from light by an insulating light-shielding film 105 except for an opening through which light is transmitted. Transparent electrode 103, light shielding film 105
An insulating film 107 is formed on the surface.

On both sides of the opening on the substrate 101, insulating columns 109 are provided. A light shielding plate 111 which is a flexible thin film is provided at an upper end of the column 109. The light shielding plate 111 has a cantilever structure, and is made of a conductive material that absorbs or reflects ultraviolet light. The conductive light-shielding plate 111 having the beam structure may be composed of a single thin film, or may be composed of a plurality of thin films.

More specifically, a metal thin film such as aluminum or chromium that reflects ultraviolet light, a single body composed of a semiconductor such as polysilicon that absorbs ultraviolet light, an insulating film such as silicon oxide or silicon nitride, or a film such as polysilicon. A configuration in which a metal is deposited on a semiconductor thin film or a composite configuration in which a filter such as a dielectric multilayer film is deposited can be employed. Shield plate 1
Numeral 11 corresponds to the shape of the opening, and is slightly larger than the size of the opening.

The flat-panel display device 115 having the light modulating section 113 having the above-described structure is connected to the ultraviolet flat light source unit 8.
1 above. Conductive light shielding plate 111 and transparent electrode 10
When no voltage is applied between the light-shielding plate 3 and the light-shielding plate 111, the light-shielding plate 111 faces the opening, and the ultraviolet light transmitted through the opening is absorbed or reflected by the light-shielding plate 111 (the state on the left side in FIG. 20).

On the other hand, when a voltage is applied between the light-shielding plate 111 and the transparent electrode 103, the light-shielding plate 111 is inclined toward the transparent electrode 103 while being twisted due to electrostatic stress acting between the two (the state on the right side in FIG. 20). That is, the shielding by the light shielding plate 111 is eliminated. Thereby, the ultraviolet light transmitted from the opening can be transmitted further forward. When the voltage is reduced to zero again, the light shielding plate 111 returns to the original position due to the elasticity of the beam.

Further, it is possible to continuously change the degree of inclination of the light shielding plate 111, that is, the amount of transmitted light, depending on the value of the voltage. By utilizing this, the gradation control by the applied voltage becomes possible.

As described above, according to the flat panel display device 115 described above, the light path of the ultraviolet light can be changed by bending the light shielding plate 111 to perform the light modulation of the ultraviolet light.

Next, a sixth embodiment of the flat panel display according to the present invention will be described. FIG. 21 is a cross-sectional view illustrating a filter unit used in the flat panel display according to the sixth embodiment.

The flat display device can be provided with various filters. For example, the light modulator and the phosphors 16a, 1
A membrane (filter) 121 is provided between the filter 6b and the filter 16c. The filter 121 is a film that transmits UV light and reflects visible light. Specifically, an interference film (a dielectric multilayer film, a metal dielectric multilayer film, or the like) that reflects UV light, a single material (α-alumina, β-alumina, or the like), a composite film thereof, or the like is used. In the drawing, reference numeral 127 denotes a black matrix formed at the boundary between the adjacent phosphors 16a, 16b, and 16c.

In the case of a flat panel display using such a filter 121, UV light is applied to the phosphors 16a, 16b, 16b.
c, and visible light is scattered and emitted. High display efficiency can be obtained by reflecting the light scattered toward the light modulating portion in the visible light toward the front surface side by the filter 121.

Further, a film (filter) 123 is provided on the surface side of the phosphors 16a, 16b, 16c. The filter 123 is a film that reflects or absorbs UV light and transmits visible light. Specifically, a sharp cut filter that absorbs UV light, an interference film that reflects UV light (a dielectric multilayer film, a metal dielectric multilayer film, or the like) is used.

In the case of a flat panel display device using this filter 123, harmful UV light is not emitted to the display surface. In addition, by reflecting UV light, it can be reused and high display efficiency can be obtained.

Note that these filters 121 and 123
May be a part other than the above. For example,
The filter 121 may be provided in the light modulator. In addition, the filter 123 may be disposed on the front surface side of the front transparent substrate 125 that is transparent to visible light.

Next, a seventh embodiment of the flat panel display according to the present invention will be described. FIG. 22 is a cross-sectional view of a flat light source used in the flat display device of the seventh embodiment, FIG. 23 is an explanatory diagram showing light emitted from the flat light source of FIG. 22, and FIG. 24 is a cross-section showing Modification Example 1 of the seventh embodiment. FIG. 25 and FIG. 25 are cross-sectional views showing Modification Example 2 of the seventh embodiment.

Various configurations are conceivable for the flat light source unit of the flat display device. As shown in FIG. 22, the flat light source unit 141 includes an ultraviolet lamp (low-pressure mercury lamp) 143, a UV light reflection plate 145, and a light guide plate 147.
, A diffusion plate 149, and a light collector 151.

The low-pressure mercury lamp 143 is arranged on the end face side of the light guide plate 147. Ultraviolet rays from the low-pressure mercury lamp 143 are incident on the end face of the light guide plate 147 by the UV light reflection plate 145. A diffusion plate 149 is provided on the surface of the light guide plate 147.
Is provided on the surface of the diffusion plate 149.
1 is provided. Ultraviolet rays incident from the end face of the light guide plate 147 are emitted through the diffusion plate 149 and the light collector 151.

According to such a flat light source unit 141, as shown in FIG. 23, it is possible to emit diffused light having directivity in the surface normal direction. The flat light source unit 141 can be suitably used for the flat display devices 91 and 115 of the above-described fourth and fifth embodiments.

As shown in FIG. 24, the flat light source unit may use a collimated light source in which the outgoing light is substantially perpendicular to the outgoing surface. The collimated light can be emitted by a known technique. U located around the lamp
This can be achieved by devising the shape of the V light reflecting plate 145, the structure of the reflecting plate 145 disposed on the back surface of the light guide plate, the structure of the light collector 151, and the like.

According to the flat light source unit 141a that emits such collimated light, the emitted light from the light guide plate 147 can be converted into a parallel beam to have directivity. The flat light source unit 141a is provided with the flat display devices 91 and 115 of the fourth and fifth embodiments described above.
Can be suitably used.

Further, as shown in FIG. 25, the flat light source unit inclines the UV light reflecting plate 145 around the lamp so that the optical path in the light guiding plate 147 becomes higher than the critical angle for total reflection. UV light may be incident on the surface.

In the flat light source unit 141b, the incident ultraviolet light travels to the terminal while totally reflecting the light guide plate 147, and is reflected by the reflector 153 provided at the terminal. Return to the side.

According to the flat light source unit 141b,
A planar light source without directivity can be obtained. This flat light source unit 141b can be suitably used for the flat display device 61 of the third embodiment described above.

Further, the flat light source unit includes a dispersion type inorganic EL (electroluminescence), a thin film type inorganic EL, a low molecular type organic EL, a polymer type organic EL, and an inorganic semiconductor LED (light emitting diode). ,
A light-emitting element that emits ultraviolet light, such as an FED (one that causes an ultraviolet light-emitting phosphor to emit light by field emission electrons), may be used.

By providing the light modulating section on the light emitting surface side of the light emitting element, light emitted from the light emitting element is directly introduced into the light modulating section.

According to the flat light source unit having such a light emitting element, uniform light emission intensity can be obtained in a more compact shape, and in particular, a voltage can be reduced for an organic EL and an inorganic LED. . Further, the life of the light source can be significantly improved for inorganic LEDs, and the life can be similarly expected to be improved for thin-film inorganic EL, organic EL, and FED.

Next, an eighth embodiment of the flat panel display according to the present invention will be described. FIG. 26 is a sectional view showing the flat panel display according to the eighth embodiment. The flat display device shown here is, for example, the flat display device 1 of FIG. 1 shown in the above-described first embodiment.
The same thing as 9 is used. Therefore, the same members are denoted by the same reference numerals, and duplicate description will be omitted. In FIG. 26, 127 indicates the adjacent phosphor 16
a, 16b, and 16c are black matrices formed at the boundaries between them. The flat panel display 161 has a gap 165 between the flat panel display 161 and the backlight unit 163, and is disposed separately.

As the substrate 167 of the light modulation section, a substrate that transmits at least UV light is used. In this case, when the ultraviolet light has a wavelength of 365 nm, the substrate 167 is preferably made of glass, acrylic resin, or the like. When the ultraviolet light has a wavelength of 245 nm, the substrate 167 is preferably made of fused quartz or the like. Further, as the substrate 169 of the phosphor part on the front side, a substrate (a general glass type) that transmits visible light is suitable.

According to the flat display device 161, the substrate 1
A gap 165 between the backlight unit 67 and the backlight unit 163
Is formed and the light modulating unit and the light emitting unit are separated, so that the substrate 167 and the backlight unit 163 can be manufactured separately. Therefore, compared to the flat display device 19 of the first embodiment in which the signal electrode 3 is formed directly on the light guide plate 1, the substrate 167,
Alternatively, a suitable material can be used for each of the light guide plates for the backlight unit. As a result, the degree of freedom in selecting the material to be used can be increased.

[0125]

As described above in detail, according to the flat display device of the present invention, the light modulator for modulating the light of the flat light source by the electromechanical operation is disposed on the flat light source of the ultraviolet light. Since the fluorescent material excited by the light from the light modulating section is disposed to face the light modulating section, it is not necessary to increase the vacuum, and the area can be increased at low cost.

A laminated structure in which a transparent signal electrode is provided on the light guide plate, a transparent flexible thin film is opposed to the signal electrode with a gap therebetween, and a scanning electrode opposed to the signal electrode is provided on the flexible thin film. Therefore, arraying is easy. Further, since the light from the light guide plate only passes through the pair of transparent electrodes sandwiching the gap, the light use efficiency can be improved.

Further, since a plurality of parallel signal electrodes and scanning electrodes formed in a strip shape are arranged in a grid pattern in the orthogonal direction, an image by phosphor emission can be obtained at each intersection of the counter electrodes, and the height can be easily increased. The image quality can be obtained, and the speed of image formation can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of a flat panel display according to the present invention.

FIG. 2 is a view as viewed in the direction of arrows AA in FIG. 1;

FIG. 3 is a cross-sectional view showing a state of the flat display device according to the present invention during operation.

FIG. 4 is a plan view illustrating a light modulation unit according to a second embodiment.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

FIG. 6 is a sectional view taken along line BB of FIG. 4;

FIG. 7 is an equivalent circuit diagram of the pixel unit shown in FIG.

FIG. 8 is a cross-sectional view illustrating a light modulator of a flat panel display according to a third embodiment.

9 is a cross-sectional view illustrating an operation state of the flat panel display device illustrated in FIG.

FIG. 10 is a plan view showing a light modulator of a flat panel display according to a fourth embodiment.

11 is a sectional view taken along line AA of FIG.

FIG. 12 is a sectional view taken along line BB of FIG. 10;

13 is a cross-sectional view illustrating an operation state of the flat panel display device illustrated in FIG.

FIG. 14 is an explanatory diagram showing spectral characteristics of a low-pressure mercury lamp for black light.

FIG. 15 is an explanatory diagram showing a light intensity transmittance of a light modulation element.

FIG. 16 is an explanatory diagram showing spectral characteristics of a backlight using a low-pressure mercury lamp.

FIG. 17 is an explanatory diagram showing the light intensity transmittance of the light modulation element.

FIG. 18 is a perspective view showing a light modulator of a flat panel display according to a fifth embodiment.

FIG. 19 is a cross-sectional view of the light modulation section shown in FIG.

20 is a cross-sectional view illustrating an operation state of the flat panel display device illustrated in FIG.

FIG. 21 is a cross-sectional view illustrating a filter unit used in the flat panel display according to the sixth embodiment.

FIG. 22 is a sectional view of a flat light source used in the flat display device according to the seventh embodiment.

FIG. 23 is an explanatory diagram showing light emitted from the flat light source in FIG. 22;

FIG. 24 is a cross-sectional view showing Modification Example 1 of the seventh embodiment.

FIG. 25 is a sectional view showing Modification 2 of the seventh embodiment.

FIG. 26 is a sectional view showing a flat panel display according to an eighth embodiment.

[Explanation of symbols]

1, 147 light guide plate 3 signal electrode (one electrode) 7, 83, 143 low-pressure mercury lamp (ultraviolet lamp) 9 flexible thin film 11 gap 13 scanning electrode (the other electrode) 14, 43, 85, 113 light modulation section 16a , 16b, 16c Phosphors 19, 21, 61, 91, 115, 161 Flat panel display device 23 TFT (active element) 25 Gate 31 Drain (one electrode) 33 Source (one electrode) 35, 71, 101, 167, 169 substrate 39 image signal line 41 scanning signal line 47 common electrode (other electrode) 51 electrode (one electrode) 53 diaphragm (flexible thin film) 57 electrode (the other electrode) 75 electrode (one electrode) 79 electrode (the other) 81, 141, 141a, 141b Planar light source 121, 123 Filter (film)

Claims (16)

[Claims] 1. A one-dimensional or two-dimensional matrix light modulator for modulating light from the flat light source by electromechanical operation is provided on a flat ultraviolet light source, and emitted from the light modulator. A flat display device, wherein a phosphor excited by light is arranged to face the light modulation section. 2. The light modulating section comprises: one electrode formed on the flat light source or on a substrate disposed between the flat light source and the phosphor; and the other electrode opposed to the one electrode with at least a gap therebetween. And a flexible thin film that is interposed between the one electrode and the other electrode and transparent to the ultraviolet light, and is generated by applying an electric field to the one electrode and the other electrode. The flat display device according to claim 1, wherein the flexible thin film is bent by the applied Coulomb force to modulate light transmitted through and emitted from the flexible thin film. 3. A plurality of strip-shaped parallel electrodes, wherein the plurality of parallel one electrodes are arranged in parallel on the flat light source or on a substrate disposed between the flat light source and the phosphor. 3. The one electrode and the other electrode are arranged in a grid pattern by arranging the other electrode in parallel with the flexible thin film in a direction perpendicular to the one electrode. A flat display device as described in the above. 4. An active element which is electrically switched is provided for each pixel, the one electrode is connected to a drain (or source) of the active element, and the other electrode is connected to a common electrode. An image signal line is connected to a source (or a drain) of the active element, a scanning signal line for each row is connected to a gate of the active element, the active element is scanned for each row, and an image signal is applied to the one electrode. 3. The flat display device according to claim 2, wherein light modulation is performed by applying active matrix driving. 5. The flat light source is constituted by an ultraviolet lamp and a light guide plate, an electric field is applied to the one electrode and the other electrode, and the flexible thin film is brought into contact with or sufficiently close to the light guide plate. 5. The flat display device according to claim 2, wherein the ultraviolet light guided to the light guide plate is transmitted and emitted to a flexible thin film side to perform light modulation. . 6. The flat display device according to claim 5, wherein the flexible thin film has a function of emitting light transmitted from the light guide plate by diffusion or scattering. 7. An optical field modulation is performed by applying an electric field to the one electrode and the other electrode to generate an optical multilayer interference effect by bending the flexible thin film. The flat display device according to any one of claims 2 to 4, wherein: 8. The flexible thin film having a light intensity reflectance with respect to the ultraviolet light, and a film disposed opposite to the flexible thin film and having a light intensity reflectance with respect to the ultraviolet light, 8. The flat panel display device according to claim 7, wherein the optical length of the film is changed by bending the flexible thin film to generate an optical multilayer interference effect, and the light of the ultraviolet light is modulated. 9. The method according to claim 1, wherein an electric field is applied to the one electrode and the other electrode, and the flexible thin film bends to change the course of the ultraviolet light, thereby performing light modulation of the ultraviolet light. The flat panel display according to claim 2. 10. The device according to claim 1, wherein a film that transmits the ultraviolet light and reflects visible light is disposed between the light modulation unit and the phosphor unit. A flat display device as described in the above. 11. The light-emitting device according to claim 1, wherein a film that absorbs or reflects the ultraviolet light and transmits visible light is disposed on an emission surface side of the phosphor part.
Item 10. The flat panel display according to item 9. 12. The light source according to claim 1, wherein the ultraviolet light of the flat light source is collimated light.
Item 10. The flat panel display according to item 9. 13. The flat display according to claim 1, wherein the flat light source uses a low-pressure mercury lamp as a light source, and the ultraviolet light has a wavelength centered at 254 nm. apparatus. 14. The flat light source according to claim 1, wherein the light source is a low-pressure mercury lamp coated with a phosphor that emits ultraviolet light, and the ultraviolet light has a wavelength around 300 nm to 400 nm. 13. The flat panel display according to any one of the above items 12. 15. The flat display device according to claim 1, wherein the flat light source is a light emitting element that emits ultraviolet light. 16. The light modulation unit according to claim 2, wherein the amount of light transmitted through the light modulation unit is arbitrarily controlled by continuously changing the flexible thin film according to the intensity of the electric field. 4. The flat panel display according to claim 1.