JP2001318370A - Liquid crystal device and electronic appliance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that in a transmission type liquid crystal device using a conventional phosphor as a coloring means, a polarizer is required to be formed on the phosphor layer and this increases the number of processes, and to eliminate such a drawback that display on a liquid crystal device is dark with low contrast because efficient formation of a polarizer with a high polarization degree is difficult. SOLUTION: A dichroic phosphor layer is formed with order of alignment in a liquid crystal device so that polarized light can be emitted with high efficiency by the light emitting from a back light. Thus, a bright liquid crystal device with low power consumption and high contrast can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device having a liquid crystal layer for changing a polarization state between substrates and forming an image by an applied voltage, and an electronic apparatus using the liquid crystal device. Yes, and more particularly, to a light emitting layer or a colored layer of a liquid crystal device.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal device capable of displaying a color image is formed by a pair of substrates 40 and 41 as shown in FIG.
0 is sandwiched. In some cases, a backlight 80 serving as a light source is provided on the back surface. Here, when the white light emitted from the backlight 80 passes through the polarizing plate 12, linearly polarized light parallel to the transmission axis of the polarizing plate 12 is transmitted, and the orthogonally polarized light component is absorbed. Further, the light transmitted through the polarizing plate 12 enters the absorption type color filters 31, 32, and 33 corresponding to red (R), green (G), and blue (B). Here, of the light incident on each color filter, light in the transmission wavelength region of each color filter is transmitted, and the other wavelength regions are absorbed. Further, when the light transmitted through the color filters 31, 32, 33 passes through the liquid crystal layer 50, its polarization direction is selected according to the voltage applied by the electrodes 20, 21, and is parallel to the transmission axis of the polarizing plate 11. The polarized light component is transmitted, and the orthogonally polarized light component is absorbed. In this way, finally, the polarizing plate 11
Only the light that has passed through reaches the viewing side.

Here, in general, the transmission wavelength region of a color filter is narrowed in order to enhance the color expression capability of a liquid crystal device, and light that can pass through the color filter is about １ ／ of light incident on the color filter. It has become about. For this reason, the intensity of the light source installed on the back of the liquid crystal device must be increased, which is a factor of increasing power consumption.

Therefore, a method using a phosphor instead of a color filter has been considered (for example, Japanese Patent Application Laid-Open No.
No. 36175). As described above, in a liquid crystal device using a phosphor instead of a color filter, a phosphor layer that excites light corresponding to red, green, and blue is disposed on the substrate, so that light absorption can be suppressed. It becomes possible.

[0005]

However, in such a liquid crystal device, since the fluorescence excited by the phosphor layer is non-polarized, it is necessary to provide a polarizer on the liquid crystal layer side with respect to the phosphor layer. Therefore, there is a problem that the number of manufacturing steps increases. Furthermore, it is difficult to manufacture an efficient polarizer, and the degree of polarization of the polarizer is reduced, which is a factor that lowers the contrast.
In addition, in order to obtain a sufficient degree of polarization, the transmittance must be reduced, and as a result, the intensity of the light source must be increased, and the power consumption increases.

The present invention has been made in view of the above circumstances, and has as its object to provide a liquid crystal device capable of producing a bright, high-contrast, good color display by effectively utilizing light. It is to provide an electronic device.

[0007]

According to the present invention, there is provided a liquid crystal display device comprising: a liquid crystal layer sandwiched between a pair of substrates; and an electrode formed on at least one of the opposing surfaces of each substrate. Further, a red phosphor layer, a green phosphor layer, and a blue phosphor layer having dichroism are formed on at least one of the substrates, and the phosphor layers are substantially oriented.

In the present invention, it is preferable that the orientation direction of the phosphor layer is substantially the same as the orientation direction of the liquid crystal layer. Thus, light incident on the liquid crystal device can be used more effectively.

Further, a color filter transmitting at least a part of the fluorescence wavelength emitted from the phosphor layer is disposed on one of the pair of substrates so as to overlap the phosphor layer corresponding to each color. Is also preferred. by this,
The display of the liquid crystal device can be sharpened, and the color range that can be reproduced can be increased.

Furthermore, in the present invention, it is preferable that a flattening film is formed on the surface of the phosphor layer. With this flattening film, defects in the liquid crystal layer due to unevenness on the substrate surface can be eliminated, so that higher display performance can be obtained.

[0011] In addition, in the present invention, it is preferable that a polarizer is formed between the phosphor layer and the liquid crystal layer. With this polarizer, a display with higher contrast can be obtained.

In the present invention, it is preferable that the phosphor layer contains a dichroic dye. Thereby, a display with higher contrast can be obtained.

On the other hand, in the present invention, it is preferable that a light source for emitting light having a wavelength for exciting the phosphor is provided on the back surface of the liquid crystal device. This allows the phosphor to emit light efficiently.

It is desirable that such a light source can emit ultraviolet light or near-ultraviolet light. Thereby, higher light use efficiency can be obtained.

On the other hand, this light source is preferably an LED or an electroluminescent element. With such a structure, power consumption can be further reduced, and a thin and lightweight liquid crystal device can be obtained.

Further, it is preferable that a structure is provided between the phosphor layer and the viewer side, the layer absorbing at least a part of the wavelength of the light for exciting the phosphor layer. Thus, the phosphor layer is not excited by light incident from the viewer side of the liquid crystal device, and the display quality is not degraded.

Further, it is preferable that a structure is provided between the phosphor layer and the viewer side, the layer reflecting at least a part of the wavelength of the light emitted from the light source. Thereby, the light transmitted through the phosphor layer can be used again, so that the light emitted from the light source can be used more effectively.

In addition, it is desirable that the phosphor layer is dispersed in a liquid crystal polymer. Thereby, stable alignment characteristics and polarization characteristics can be obtained.

According to another aspect of the invention, there is provided an electronic apparatus including the above-described liquid crystal device. ADVANTAGE OF THE INVENTION According to this invention, as a result of making effective use of light, a bright color display with high contrast ratio with low power consumption becomes possible.

[0020]

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

(First Embodiment) First, a liquid crystal device according to a first embodiment of the present invention will be described. This liquid crystal device is driven by an active matrix driving method using a TFD (Thin Film Diode) element. FIG.
FIG. 2 is a cross-sectional view illustrating a configuration of the liquid crystal device. FIG.
In order to make each layer or each member in the above-mentioned size recognizable on the drawings, the scale of each layer or each member is different.

Here, the display principle of the liquid crystal device according to the present embodiment will be described. Light emitted from a backlight 85 having an LED capable of irradiating near-ultraviolet light of 380 nm or less as a light source is applied to phosphor layers 101, 102, and 103 in which phosphors having dichroism are substantially oriented. Incident. At this time,
Since the phosphor layers 101, 102, and 103 have dichroism and are oriented, near-ultraviolet light having a component parallel to the light emission axis is excited, so that light is emitted with linearly polarized light. Furthermore, the linearly polarized light emitted from the phosphor layers 101, 102, and 103 enters the liquid crystal layer 50 that has been twisted by 90 ° by the alignment process. At this time, the polarization state is selected by the voltage applied to the electrodes 20 and 21. Then, the light enters the polarizing plate 11 provided on the viewing side of the liquid crystal device.
Only the polarization component parallel to the transmission axis of the polarizing plate 11 is transmitted,
The light exits to the viewing side.

The near-ultraviolet light incident from the observer side of the liquid crystal device (ie, the upper part of FIG. 2) causes the phosphor layer 101,
An ultraviolet light absorbing film 15 is provided to prevent excitation of 102 and 103. Note that the polarizing plate 11 may be configured to also serve as the ultraviolet light absorbing film 15.

Next, the opposite substrate on which the phosphor layers 101, 102 and 103 are formed will be described. First, a photosensitive organic film containing carbon black is formed on the second substrate 41.
After coating by a spin coating method with a thickness of μm, a pattern having a width of 20 μm is formed by a photolithography method to form a light shielding layer 39.

Further, a polymer film made of polyimide or the like is formed on the second substrate 41 as an opposite substrate in a thickness of 10 nm to 100 nm.
A dichroic phosphor (NK-4562) that is formed to a thickness of (100 Å to 1000 Å), rubbed, and then excites light corresponding to red.
Was added to a liquid crystal polymer (PLC-7023) at a ratio of 1 wt%, and a solvent diluted with dichlorohexic acid to a solid component of 20 wt% to a thickness of 1 μm by a spin coater method, flexographic printing method, or the like. ~ 5 μm
(10000 angstroms to 50000 angstroms). Next, peeling is performed using toluene or the like by using a photolithography method so that a liquid crystal polymer film containing a phosphor remains only in a pixel portion corresponding to red. Using a similar technique, a dichroic phosphor (NSD + COUMAR) that excites light corresponding to green is used.
IN6: a polymerization ratio of 1: 1) and a liquid crystal polymer film containing a dichroic phosphor (BBOT) that excites light corresponding to blue are formed. At this time, the liquid crystal polymer has an alignment order in the direction of the rubbing treatment performed on the second substrate 41, and similarly, the dichroic phosphor also has an alignment order in the direction of the rubbing treatment.

A transparent acrylic resin monomer is applied on the liquid crystal polymer film containing the dichroic phosphor prepared as described above for flattening the surface and protecting the liquid crystal polymer film by spin coating. And 3 μm (30000
(Angstrom) transparent acrylic resin layer 30 is formed. Further, a transparent conductive thin film made of ITO or the like is formed and patterned by photolithography to form the electrodes 20 in a stripe shape.

Next, an element substrate on which a TFD element is formed will be described with reference to FIGS. Here, FIG. 3 is a plan view showing the configuration of one pixel on the element substrate, and FIG. 4 is a cross-sectional view showing the structure of the TFD element. The TFD element 301 is formed on an insulating film 312 formed on the first substrate 40 with a base as a base,
The first metal film 302 and the insulating layer 3 are sequentially arranged from the insulating film 312 side.
04 and the second metal film 306, and have a TFD structure (Thin Film Diode structure) or an MIM structure (Metal
Insulator Metal structure). And the TFD element 3
01 is connected to a wiring 311 serving as a data line or a scanning line formed on the first substrate 40 as an element substrate, and the second metal film 306 is a transparent electrode serving as a pixel electrode. It is connected to the electrode 21, on which an insulating layer 303 is formed.

After an orientation film (not shown) is applied to each of the opposing surfaces of the opposing substrate and the element substrate and subjected to rubbing, a stripe-shaped electrode 20 serving as a scanning line or a data line, and a wiring are formed. The two substrates are bonded together via a sealing material 45 so that the electrodes 311 are orthogonal to each other and the electrodes 20 and the pixel electrodes 21 are opposed to each other. Is sealed with a sealing material (not shown).

According to the liquid crystal device according to the first embodiment, since the light use efficiency can be improved, the power consumption of the light source 85 can be suppressed, and a good color display with high brightness and high contrast ratio can be performed. Becomes

In the first embodiment, the rubbing direction of the opposing substrate is preferably parallel or perpendicular to the rubbing direction performed at the time of forming the liquid crystal polymer film containing the dichroic phosphor. By doing so, the light use efficiency can be further increased.

In the first embodiment, an active matrix driving type liquid crystal device using a TFD element has been described. However, an active matrix type liquid crystal device using a TFT element, which will be described later, or a passive matrix driving type liquid crystal device. It may be a device.

Further, in the first embodiment, a color which allows at least a part of the excitation light of each phosphor layer to be transmitted to the upper part of the phosphor layers 101, 102 and 103 or the element substrate opposed thereto. A configuration in which a filter is provided so as to overlap each phosphor layer may be adopted. With such a configuration, the ability of the liquid crystal device to express colors can be enhanced.

In addition, the phosphor layers 101, 102, 10
A configuration in which a polarizer is formed between 3 and the liquid crystal layer 50 may be adopted. With this configuration, the contrast ratio of the liquid crystal device can be increased.

Further, the phosphor layers 101, 102, 103
A reflective layer that reflects near-ultraviolet light emitted from the backlight 85 may be formed between and the viewing side. Accordingly, the light transmitted through the phosphor layers 101, 102, and 103 is again incident on the phosphor layers 101, 102, and 103, so that the light emitted from the backlight 85 can be used more effectively.

(Second Embodiment) Next, a liquid crystal device according to a second embodiment of the present invention will be described. This liquid crystal device is driven by an active matrix driving method using a TFT (Thin Film Transistor) element. FIG. 5 is a sectional view showing the configuration of the liquid crystal device. In order to make each layer and each member in FIG. 5 recognizable in the drawing, the scale of each layer and each member is different.

Here, the display principle of the liquid crystal device according to the present embodiment will be described. Light emitted from a backlight 90 having an electroluminescent element capable of irradiating near-ultraviolet light of 380 nm or less as a light source passes through a transparent substrate 41, and then a dichroic phosphor has an orientational order. Incident on the phosphor layers 101, 102, 103 formed.
At this time, since the phosphor layers 101, 102, and 103 have dichroism and have an orientational order, near-ultraviolet light having a component parallel to the emission axis is excited, and as a result, linearly polarized light is emitted. Emits light.

Further, the phosphor layers 101, 102, 103
Is transmitted through the dielectric thin film 110 and then twisted by 90 ° by the alignment process.
Incident on. At this time, the polarization state is selected by the voltage applied to the electrodes 20 and 21. Then, the light enters the polarizing plate 11 provided on the observer side. Among them, only the polarized light component parallel to the transmission axis of the polarizing plate 11 is transmitted and emitted to the viewer side.

It is to be noted that, of the light emitted from the backlight 90, the light transmitted through the phosphor layers 101, 102 and 103
The near ultraviolet light of 60 nm to 370 nm is applied to the dielectric thin film 110.
As a result of reflection by a reflector (not shown) provided on the back surface of the backlight 90.
01, 102 and 103 again. Thus, the light emitted from the backlight 90 is effectively used. Further, since near-ultraviolet light incident from the observer side is reflected by the dielectric thin film 110, excitation of the phosphor layers 101, 102, and 103 is prevented. Therefore, the ultraviolet light absorbing film 15 provided in the first embodiment (see FIG. 2) is not provided in the present embodiment, but the ultraviolet light absorbing film may be provided in the present embodiment. Of course. Also,
The polarizing plate 11 may be configured to also serve as the ultraviolet absorbing film.

Next, the opposite substrate on which the phosphor layers 101, 102 and 103 are formed will be described. First, a polymer film made of polyimide or the like is formed on the second substrate 41 in a thickness of 10 nm to 1 nm.
After forming with a thickness of 00 nm (100 Å to 1000 Å) and performing a rubbing treatment,
A dichroic phosphor (NK-45) that excites light corresponding to red
62) was added to the liquid crystal polymer (PLC-7023) by 1 wt.
%, And then a solvent diluted with dichlorohexic acid so that the solid component becomes 20 wt% has a film thickness of 1 μm or less by a spin coater method, a flexographic printing method, or the like.
The coating is uniformly applied to a thickness of 5 μm (10000 Å to 50,000 Å). Then
By photolithography, peeling is performed using toluene or the like so that a liquid crystal polymer film containing a phosphor remains only in a pixel portion corresponding to red. Using a similar technique, a dichroic phosphor (NSD + COU) that excites light corresponding to green
A liquid crystal polymer film containing MERIN6: polymerization ratio 1: 1) and a dichroic phosphor (BBO) that excites light corresponding to blue.
And a liquid crystal polymer film containing T). At this time, the liquid crystal polymer has an alignment order in the direction of the rubbing treatment performed on the second substrate 41, and similarly, the dichroic phosphor also has an alignment order in the direction of the rubbing treatment.

Subsequently, the phosphor layers 101, 102, 103
A dielectric thin film 110 that reflects near-ultraviolet light is formed on top of the substrate. Such a dielectric thin film 110 is a SiO ₂ thin film,
It can be manufactured by laminating a TiO thin film by a sputtering method.

Further, a polarizer 1 having an axis in a direction parallel to the orientation direction of the dichroic phosphor is provided on the dielectric thin film 110.
20 is formed. As a method for forming the polarizer 120, a polymer thin film made of
(100 .ANG. To 1000 .ANG.), Rubbing, and then forming a liquid crystal polymer containing iodine by a spin coater method. Thereafter, a transparent conductive thin film made of ITO or the like is formed, and the counter electrode 21 is formed.

Next, an element substrate on which a TFT element is formed will be described with reference to FIGS. Here, FIG.
Is a plan view showing a configuration of one pixel on an element substrate, and FIG. 7 is a cross-sectional view showing a structure of a TFT element.
A first insulating film 591 is formed as a base film on a first substrate 540, and a semiconductor region including a source region 551, a channel region 552, and a drain region 553 is formed on the surface thereof. It is covered with the second insulating film 592 by the processing. 593 and 594 are interlayer insulating films.

A scanning line 512 is formed immediately above the channel region 552. That is, the scanning line 512
Of the TFT elements 501
Is configured to function as a gate electrode. Further, the data line 522 is connected to the source region 551 via the contact hole 505, while the pixel electrode 20 is connected to the drain region 553 via the contact hole 508.

The first substrate 540 is, for example, a transparent glass substrate, a quartz substrate, or the like.
Is made of an insulating and transparent substrate such as glass and plastic. In the present embodiment,
The TFT element 501 includes a source region 551 and a drain region 55 using the gate electrode of the scan line 512 as a mask.
3 has a self-line structure.
A structure or an offset structure may be used. Further, in the present embodiment, a planar type is used, but a bottom gate type may be used. In addition, the TFT 501 may have a single gate structure, a dual gate structure or a triple gate structure or more.

Then, an orientation film (not shown) is applied to each of the opposing surfaces of the opposing substrate and the element substrate, and rubbing treatment is performed.
Then, the liquid crystal is sealed in the space between the two substrates, and then sealed with a sealing material (not shown).

According to the liquid crystal device according to the second embodiment, since the light use efficiency is improved, it is possible to suppress the power consumption of the light source 90, and to perform a bright color display with a high contrast ratio. Becomes

In the second embodiment, the rubbing direction of the opposing substrate is preferably parallel or perpendicular to the rubbing direction performed at the time of forming the liquid crystal polymer film containing the dichroic phosphor. By doing so, the light use efficiency can be further increased.

Further, in the second embodiment, the active matrix driving type liquid crystal device using the TFT element has been described. However, as in the first embodiment, the active matrix type liquid crystal device using the TFD element and the passive matrix type liquid crystal device can be used. A liquid crystal device of a matrix drive system may be used.

In the second embodiment, the phosphor layer 1
A color filter that allows at least a part of the excitation light of each phosphor layer to pass therethrough is provided on top of 01, 102, and 103 or on an element substrate opposed thereto so as to overlap each phosphor layer. It is good also as a configuration. With such a configuration, the ability of the liquid crystal device to express colors can be enhanced. In addition, when a color filter is provided, a display without unevenness can be obtained by forming a flattening film made of an acrylic resin or the like for flattening on the color filter.

By dispersing a dichroic dye in the phosphor layers 101, 102, and 103, the degree of polarization of linearly polarized light emitted from the phosphor can be increased.

(Third Embodiment) FIG. 8 shows an example of an electronic apparatus according to the present invention. This is an electronic book, which is a kind of portable information terminal. Reference numeral 600 denotes an electronic book main body,
Reference numeral 601 denotes a liquid crystal unit using the liquid crystal device of the present invention.

FIG. 9 shows a mobile phone as another example of the present invention. Reference numeral 605 denotes a mobile phone main body, and reference numeral 606 denotes a liquid crystal display unit using the liquid crystal device of the present invention. Since these electronic devices are provided with the liquid crystal device according to the present invention, light is effectively used, and as a result, a bright color display with a high contrast ratio and low power consumption can be performed.

[0053]

As described above, according to the present invention, a good color display with low power consumption, high brightness and high contrast ratio can be realized by effective use of light.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a conventional liquid crystal device.

FIG. 2 is a cross-sectional view illustrating a configuration of the liquid crystal device according to the first embodiment of the present invention.

FIG. 3 is a plan view showing a configuration for one pixel on an element substrate of the liquid crystal device.

FIG. 4 is a cross-sectional view showing a configuration of a TFD element on the element substrate.

FIG. 5 is a cross-sectional view illustrating a configuration of a liquid crystal device according to a second embodiment of the present invention.

FIG. 6 is a plan view showing a configuration for one pixel on an element substrate of the liquid crystal device.

FIG. 7 is a cross-sectional view illustrating a configuration of a TFT element on the element substrate.

FIG. 8 is a perspective view illustrating an example of an electronic apparatus using the liquid crystal device of the present invention.

FIG. 9 is a perspective view illustrating another example of an electronic apparatus using the liquid crystal device of the present invention.

[Explanation of symbols]

11, 12 ... Polarizing plate 15 ... Ultraviolet light absorbing film 20, 21 ... Electrode 30 ... Acrylic resin layer 39 ... Light shielding layer 40, 41, 340, 540 ... Substrate 45 ... Sealing agent 50 ... Liquid crystal layer 101, 102, 103 ... Fluorescence Body layer 80, 85, 90: backlight 301: TFD element 303, 304, 312, 591, 592, 593, 5
94 insulating film 306 second metal film 311, 512 scanning line 120 polarizer 110 dielectric thin film layer 522 data line 501 TFT element 505, 508 contact hole 551 source region 552 channel region 553 Drain region

Claims (15)

[Claims] 1. A liquid crystal layer is sandwiched between a pair of substrates, electrodes are formed on at least one of opposing surfaces of each substrate, and at least one of the substrates has a dichroic red fluorescent light. A liquid crystal device, wherein a body layer, a green phosphor layer, and a blue phosphor layer are formed, and the phosphor layers are substantially oriented. 2. The liquid crystal device according to claim 1, wherein the orientation direction of the phosphor layer and the orientation direction of the liquid crystal layer are substantially the same. 3. A color filter that transmits at least a part of the fluorescent wavelength emitted by the phosphor layer is disposed on one of the pair of substrates so as to overlap the phosphor layer corresponding to each color. The liquid crystal device according to claim 1, wherein: 4. The liquid crystal device according to claim 1, wherein a flattening film is formed on a surface of the phosphor layer. 5. The liquid crystal device according to claim 3, wherein a flattening film is formed on a surface of the color filter. 6. A polarizer is formed between the phosphor layer and the liquid crystal layer.
3. The liquid crystal device according to claim 1. 7. The liquid crystal device according to claim 1, wherein a dichroic dye is contained in the phosphor layer. 8. The liquid crystal device according to claim 1, further comprising a light source that emits light including a wavelength that excites the phosphor, on a back surface of the liquid crystal device. 9. The liquid crystal device according to claim 8, wherein the light source is capable of emitting ultraviolet light or near ultraviolet light. 10. The light source is an LED (Light Emitting).
10. The liquid crystal device according to claim 8, wherein the liquid crystal device is a diode. 11. The liquid crystal device according to claim 8, wherein the light source is an electroluminescence element. 12. Between the phosphor layer and the viewing side,
The liquid crystal device according to claim 8, further comprising a layer that absorbs at least a part of the wavelength of light that excites the phosphor layer. 13. The light-emitting device according to claim 8, further comprising a layer that reflects at least a part of the wavelength of light emitted from the light source between the phosphor layer and the viewer. A liquid crystal device according to any one of the above. 14. The liquid crystal device according to claim 1, wherein the phosphor layer is dispersed in a liquid crystal polymer. 15. An electronic apparatus comprising the liquid crystal device according to claim 1.