JPH11282004A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to manufacture a liquid crystal display device at a comparatively low cost in a high yield by varying a conductivity of a photo conductive layer by switching plural light sources, switching an electric connection between a region of the photo conductive layer irradiated with light and a signal electrode, and optically addressing to the liquid crystal layer. SOLUTION: A plasma emission cell 200b has plural plasma emission channels 25a where a gap between a substrate 16 and a substrate 19 is divided by plural rib barriers 17. The plasma emission channels 25a are sealed with an ionizable gas, and plasma is generated by impressing an electrical discharge pulse voltage between a cathode 18a and an anode 18b. The plural plasma emission channels 25a extend in the direction orthogonal to a signal electrode 15. Therefore, the regions of the photo conductive layer 14 to be electrically connected with the signal electrode 15 are line-sequentially selected by controlling ON-OFF of the plasma emission channel 25a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device that addresses a liquid crystal layer using light.

[0002]

2. Description of the Related Art Liquid crystal display devices are classified into an electric addressing method, a thermal addressing method, and an optical addressing method according to their driving methods. Among them, the passive matrix (PM) method and the active matrix (AM) method of the electric addressing method which are currently most frequently used as the direct-view display device are currently used.

In recent years, there has been an increasing need for larger and higher definition display devices. However, the liquid crystal display device of the conventional type cannot sufficiently meet these needs, and a commercially available product has a diagonal of 20 inches and a diagonal of 3 even in the prototype stage.
At present, about 0 inches is the limit. In particular, the PM method has a problem that the contrast is reduced due to crosstalk as the number of pixels increases. Further, the AM method has a problem that it is difficult to form a large number of switching elements (especially thin film transistors: TFTs) without defects.

On the other hand, as an AM type liquid crystal display device which does not use a semiconductor switching element such as a TFT, a 19
In 1990, T. Buzak of Tektronix of the United States developed a plasma-addressed liquid crystal display device (PALC) (for example, Japanese Patent Application Laid-Open No. 1-217396). FIG. 1 schematically shows a cross-sectional structure of PALC.

[0005] The PALC 100 has a configuration in which a liquid crystal cell and a plasma cell are stacked. The liquid crystal layer 3 is sandwiched between the substrate 1 and the dielectric separator 4, and the liquid crystal layer 3 is driven by a potential difference between the signal electrode (column electrode) 2 and the dielectric separator 4. The plasma cell has a plurality of plasma discharge channels 5 in which a gap between a substrate 9 and a dielectric separator 4 is divided by a plurality of rib partition walls 6. An ionizable gas is sealed in the plasma discharge channel 5, and a plasma is generated by applying a discharge pulse voltage between the cathode 7 and the anode 8. The plurality of plasma discharge channels 5 extend in a direction orthogonal to the signal electrodes (column electrodes) 2, and the cathode 7 and the anode 8 function as scanning electrodes (row electrodes) 10, and are scanned line-sequentially.

[0006]

The liquid crystal display device using the above-described PALC system can be relatively easily enlarged in size as compared with a liquid crystal display device using a TFT. However, the dielectric separator 4 used for PALC is a thin plate made of glass, which is expensive and difficult to handle as the display device becomes larger, and the probability of breakage during the fabrication of the display device increases.

Further, when the PALC is driven, the plasma-side surface of the thin glass acts as a pseudo electrode. The thickness of the glass is about 50 to 100 μm, which is a thickness of a general nematic liquid crystal layer. It has a thickness of 10 times or more compared to a certain 3 to 6 microns. For this reason, when driving the PALC, it is necessary to apply a voltage ten times or more the voltage for effectively driving the liquid crystal layer. This causes problems such as an increase in the load on the drive circuit, an increase in power consumption, and accompanying heat generation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a low cost suitable for enlargement and high definition.
It is an object to provide a liquid crystal display device with a high yield.

[0009]

The liquid crystal display device of the present invention comprises:
A first substrate, a second substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, and a single first electrode provided on the liquid crystal layer side of the first substrate. A plurality of stripe-shaped signal electrodes that are provided on the liquid crystal layer side of the second substrate and are made of a transparent conductive material and extend in a first direction and that are parallel to each other; and a photoconductive layer that covers the plurality of signal electrodes. A plurality of parallel stripe-shaped light sources that are provided outside the second substrate and irradiate at least a part of the photoconductive layer with light and extend in a second direction different from the first direction. Changing the electrical conductivity of the photoconductive layer by switching the plurality of light sources, switching the electrical connection between the light-irradiated region of the photoconductive layer and the signal electrode, and switching the liquid crystal layer; Therefore, the above object can be achieved.

Another liquid crystal display device according to the present invention comprises a first substrate, a second substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, and the liquid crystal of the first substrate. A plurality of first electrodes in the form of stripes parallel to each other and provided on the layer side and extending in the first direction; and provided on the liquid crystal layer side of the second substrate;
A plurality of stripe-shaped signal electrodes extending in a second direction different from the first direction and made of a transparent conductive material, a photoconductive layer covering the plurality of signal electrodes, and an outer surface of the second substrate. And a plurality of light sources in a stripe shape extending in the second direction and illuminating at least a part of the photoconductive layer. The light sources are switched by switching the plurality of light sources. Since the electrical conductivity of the conductive layer is changed, the electrical connection between the light-irradiated region of the photoconductive layer and the signal electrode is switched, and the liquid crystal layer is optically addressed, the above object can be achieved. it can.

Another liquid crystal display device according to the present invention comprises a first substrate, a second substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, and the liquid crystal of the first substrate. A single first electrode provided on the layer side, and a plurality of parallel striped signal electrodes provided on the liquid crystal layer side of the second substrate and made of a transparent conductive material and extending in a first direction; An insulating layer formed on the plurality of signal electrodes, a photoconductive layer formed between the plurality of signal electrodes and the insulating layer, and a through hole formed in the insulating layer. A plurality of pixel electrodes connected to the photoconductive layer; and a plurality of pixel electrodes provided outside the second substrate and irradiating at least a portion of the photoconductive layer with light, and extending in a second direction different from the first direction. A plurality of stripe-shaped light sources parallel to each other, and The electrical conductivity of the conductive layers is changed, switching the electrical connection between the pixel electrode and the signal electrode, by its, since light address the liquid crystal layer, it is possible to achieve the above object.

Another liquid crystal display device according to the present invention comprises a first substrate, a second substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, and the liquid crystal of the first substrate. A plurality of first electrodes in the form of stripes parallel to each other and provided on the layer side and extending in the first direction; and provided on the liquid crystal layer side of the second substrate;
A plurality of stripe-shaped signal electrodes extending in a second direction different from the first direction and made of a transparent conductive material, an insulating layer formed on the plurality of signal electrodes, and the plurality of signal electrodes And a photoconductive layer formed between the insulating layer,
A plurality of pixel electrodes connected to the photoconductive layer through a through hole formed in the insulating layer; and a plurality of pixel electrodes provided outside the second substrate, and irradiating at least a part of the photoconductive layer with light. A plurality of light sources in the form of stripes extending in the second direction in parallel with each other, and changing the electrical conductivity of the photoconductive layer by switching the plurality of light sources; Since the electrical connection between the light-irradiated region and the signal electrode is switched, thereby optically addressing the liquid crystal layer, the above object can be achieved.

[0013] The photoconductive layer may include at least one dot-shaped photoconductive film disposed for each of the plurality of pixel electrodes.

[0014] The storage device may further include a storage capacitor electrically connected to the pixel electrode.

[0015] The first electrode may include a transparent conductive layer, and the first electrode layer may further include a metal electrode electrically connected to the first electrode.

[0016] The photoconductive layer may include a substance whose electric conductivity changes by ultraviolet light, and may be configured to perform display in a transmission mode or a reflection mode.

[0017] The photoconductive layer may include a substance whose electric conductivity changes by visible light, and may be configured to perform display in a reflection mode.

[0018] The photoconductive layer may be a single photoconductive film.

The photoconductive layer may comprise a plurality of striped photoconductive films parallel to the plurality of striped signal electrodes.

The plurality of light sources may have a plasma emission channel filled with an ionizable gas.

[0021] The plurality of light sources may further include a phosphor for converting ultraviolet light generated from the plasma emission channel into visible light.

Hereinafter, the operation of the present invention will be described.

The liquid crystal display device of the present invention has a signal electrode, a photoconductive layer covering the signal electrode, and a plurality of light sources for irradiating the photoconductive layer with light. By selectively irradiating the photoconductive layer with light, a region of the photoconductive layer that is electrically connected to the signal electrode can be selected (for example, columns are line-sequentially). Therefore, the voltage applied between the selected region of the photoconductive layer and the counter electrode can be line-sequentially scanned by switching the light source. That is, the liquid crystal layer can be optically addressed.

For example, when a photoconductive layer formed on a plurality of stripe-shaped signal electrodes extending in the row direction is irradiated with light in a stripe shape extending in the column direction (perpendicular to the row direction), the light-irradiated region and the signal A region where the electrode intersects is selected (predetermined voltage). Therefore, a predetermined voltage is applied to the liquid crystal layer between the counter electrode and the light-irradiated region of the photoconductive layer. When the striped signal electrode and the striped light source are configured to be orthogonal to each other, a single counter electrode can be used.

When the photoconductive layer formed on a plurality of stripe-shaped signal electrodes extending in the row direction is irradiated with light in a stripe shape parallel to the signal electrodes, the photoconductive layer is selected for each row (predetermined). Voltage). Therefore, when the electrodes on the counter substrate side are a plurality of stripe-shaped electrodes (scanning electrodes) extending in the column direction, a predetermined voltage is applied to the liquid crystal layer located at the intersection of the scanning electrodes and the signal electrodes.

The light source of the liquid crystal display device according to the present invention can have, for example, a configuration similar to a PALC plasma cell. In the conventional PALC, the plasma discharge channel 5 needs to be electrically coupled to the liquid crystal layer 3 via the dielectric separator 4. Therefore, it is necessary to use a very thin glass sheet as the dielectric separator 4. On the other hand, the plasma cell as a light source used in the liquid crystal display device of the present invention only needs to be able to irradiate enough light to sufficiently change the electrical conductivity of the photoconductive layer. Therefore, as long as the light intensity and the sensitivity of the photoconductive layer are sufficient, there is no limitation on the thickness of the substrate provided between the plasma light emitting portion and the photoconductive layer, and handling in the manufacturing process is taken into consideration. It can be designed appropriately.

[0027]

Embodiments of the present invention will be described below.

(Embodiment 1) The liquid crystal display device 200 according to the present embodiment is schematically shown in FIG. Liquid crystal display device 200
Has a liquid crystal cell 200a and a plasma light emitting cell 200b. Liquid crystal cell 200a and plasma light emitting cell 20
The substrate 16 is shared with 0b. This substrate 16
This corresponds to a dielectric separator of conventional PALC (reference numeral 4 in FIG. 1).

The liquid crystal cell 200a has a liquid crystal layer 13 between a substrate 11 (first substrate) and a substrate 16 (second substrate). On the surface of the substrate 11 on the liquid crystal layer 13 side, a counter electrode 12 made of a transparent conductive material such as ITO (indium tin oxide) is formed on almost the entire display area. If necessary, color filters may be formed.

On the surface of the substrate 16 on the liquid crystal layer 13 side, a plurality of stripe-shaped signal electrodes 15 and signal electrodes 1 parallel to each other are provided.
5, a photoconductive layer 14 is formed. Photoconductive layer 14
Are formed over almost the entire display area.

The liquid crystal layer 13 can be formed using a liquid crystal material used in a conventional active matrix type liquid crystal display device. For example, a liquid crystal material such as a nematic liquid crystal or a cholesteric liquid crystal can be used.
Further, an alignment film may be formed on the surfaces of the substrates 11 and 16 that are in contact with the liquid crystal layer 13 as necessary.

The plasma light emitting cell 200b has a plurality of plasma light emitting channels 25a in which a gap between the substrate 16 and the substrate 19 is divided by a plurality of rib partition walls 17. An ionizable gas is sealed in the plasma emission channel 25a, and a plasma is generated by applying a discharge pulse voltage between the cathode 18a and the anode 18b. The plurality of plasma emission channels 25a extend in a direction orthogonal to the signal electrodes 15 (Type I). Therefore, by controlling ON / OFF of the plasma emission channel 25a, a region of the photoconductive layer 14 electrically connected to the signal electrode 15 is selected (scanned) line-sequentially.
In this configuration, since the photoconductive layer 14 located at the intersection of the signal electrode 15 and the plasma emission channel 25a is selected, the counter electrode 12 can be a single electrode.

The plasma light emitting cell 200b may have the same configuration as the plasma discharge cell of PALC. Instead of providing the plurality of rib barrier ribs 17 on the substrate 19, the plasma emission channel 25a may be formed by etching a thick substrate. Further, in order to enhance the luminous efficiency, the type and the gas pressure of the gas sealed in the plasma light-emitting channel 25a may be optimized. For example, when emitting ultraviolet light, for example, helium, xenon, or a mixed gas thereof can be used. In order to emit visible light, a mixed gas of neon and xenon is used, or the plasma emission channel 25 is used.
A suitable phosphor may be applied to the inner wall of a to convert ultraviolet rays into visible light. The use of ultraviolet light as addressing light has the advantage that a transmission type liquid crystal display device can be formed.

In the liquid crystal display device according to the present invention, if the intensity of light from the light source for optical addressing and the sensitivity of the photoconductive layer are sufficient, the liquid crystal cell 200a and the plasma cell 200
There is no limitation on the material or thickness of the substrate 16 provided between the substrate 16 and the substrate 16, and it can be appropriately set in consideration of the yield of the manufacturing process. When ultraviolet rays are used, for example, a quartz substrate or a fused silica substrate can be used. When a large-screen display device is configured, the substrate 16 may include a plurality of substrates.

The material of the photoconductive layer 14 may be a material whose electric conductivity is sufficiently changed with respect to the addressing light, from a known material in consideration of the wavelength and intensity of the addressing light and the configuration of the device. Just choose. For ultraviolet light, for example,
Titanium oxide can be used. For visible light, for example, amorphous silicon can be used.

A so-called plasma display device (PDP) is known as a display device using plasma emission. P
DP is a self-luminous display device that converts ultraviolet light emitted by plasma into visible light with a phosphor and uses the visible light for display. In contrast, in the liquid crystal display device according to the present invention, light obtained by plasma emission is used for addressing pixels. Light used for display is light from a backlight in the case of a transmissive type, and is ambient light in the case of a reflective type, as in a conventional liquid crystal display device. Therefore, the intensity of plasma emission only needs to be able to sufficiently change the electrical conductivity of the photoconductive layer, and relatively weak light can be used. For example, in the case of using ultraviolet light by plasma emission, it is not necessary to use the bright line, and optimization may be performed in consideration of the sensitivity of the photoconductive layer and the transmittance characteristics of the material of the substrate and the signal electrode.

The operation principle of the liquid crystal display device 200 according to the present embodiment will be described with reference to FIG. Cathode 18a and anode 1 in selected plasma emission channel 25a
8b by applying a discharge pulse voltage to
The gas in the plasma emission channel 25a is ionized,
Plasma is generated. The plasma generates light of various wavelengths depending on the type and pressure of the gas (FIG. 3A).

This light is applied to the substrate 16 (and the signal electrode 15).
And is applied to the photoconductive layer 14. The light-irradiated region 14a increases the electrical conductivity of the photoconductive layer 14, becomes a conductor, and is electrically connected to the signal electrode 15. Accordingly, the potential of the light-irradiated region 14a becomes the same as the potential of the signal electrode. Therefore, when a drive voltage is applied between the counter electrode 12 and the signal electrode 15, the light-irradiated region 14a of the photoconductive layer 14 A voltage is applied to the liquid crystal layer 13 between the counter electrode 12 and the liquid crystal layer 13a in a region corresponding to the pixel is driven (FIG. 3B).

Next, when the voltage between the cathode 18a and the anode 18b is turned off and the plasma emission is stopped, the electric conductivity of the photoconductive layer 14 is reduced and the photoconductive layer 14 becomes an insulator, and the signal electrode 1
5 is electrically insulated. Signal electrode 15 / photoconductive layer 1
Since the 4 / liquid crystal layer 13 / counter electrode 12 functions as a capacitor, a charge corresponding to the previously applied drive voltage is held on the photoconductive layer 14, and the drive state of the liquid crystal layer 13 is held (so-called. Sample hold) (Fig. 3
(C)). In the state in which the plasma emission is stopped (quenching state), even if a driving voltage is applied between the counter electrode 12 and the signal electrode 15, the signal electrode 15 and the photoconductive layer 14 are electrically separated. Due to the capacitance division between the photoconductive layer 14 and the liquid crystal layer 13, a sufficient voltage is not applied to the liquid crystal layer 13. In the next frame (or field), a new drive voltage is applied to the liquid crystal layer 13 during a period in which the plasma emission channel 25a is selected (period of plasma emission).

The liquid crystal display device 200 of this embodiment can be manufactured by the same manufacturing method as that of a conventional plasma addressed liquid crystal display device (PALC) or plasma display device (PDP). Liquid crystal display device 2 of the first embodiment
An example of the manufacturing method 00 will be described with reference to FIGS. 4A to 4C.

As shown in FIGS. 4A (a) and (b),
For example, on a glass substrate 11 having a thickness of about 1.1 mm, a thickness of about 5 mm
0 nm ITO is formed by sputtering, and the counter electrode 1 is formed.
Form 2 If necessary, an alignment film and a color filter may be formed.

As shown in FIGS. 4A to 4C, for example, a rib partition 17 having a height of about 200 μm is formed by etching a glass substrate 19 having a thickness of about 1.1 mm using hydrofluoric acid or the like. I do. Alternatively, the rib partition walls 17 may be formed on the substrate 19. Discharge electrodes 18a and 1
8b can be formed, for example, by forming a nickel film having a thickness of about 1 μm by a sputtering method and etching it.

As shown in FIGS. 4C (a) to 4 (c), the substrate 16 (for example, about 0.7 mm
On a thick quartz substrate), a transparent conductive film having a thickness of about 15 nm is formed by, for example, a sputtering method (FIG. 4A), and etched in a stripe shape to form a signal electrode 15 (FIG. 4).
(B)). About 0.1% so as to cover almost the entire surface of the substrate.
A μm titanium oxide film is formed by a sputtering method, and a photoconductive layer 1 is formed.
4 is obtained (FIG. 4C). Thereafter, if necessary, an alignment film may be formed and a rubbing treatment may be performed.

After the obtained substrates 16 and 19 are bonded to each other and the inside of the groove is decompressed, for example, a mixed gas of helium and xenon is sealed, and the plasma emission channel 25a is formed.
To form When a large panel is formed, a plurality of substrates 16 may be attached to one substrate 19.

The substrate 11 and the substrate 16 are bonded to each other with the respective electrodes inside, while controlling the gap using an appropriate spacer. A desired liquid crystal material is injected into this gap to form a liquid crystal layer 13 and a liquid crystal display device 20.
0 is created. The liquid crystal display device 200 of the present embodiment includes:
Since a transparent substrate is used and ultraviolet rays are used as address light, display can be performed in a transmission mode.

In the above-described example, the photoconductive layer 14 is formed on almost the entire display area, but it is not always necessary. Since the photoconductive layer 14 is provided for switching the electrical connection with the signal electrode 15 by light, for example, as shown in FIG. May be formed.

The liquid crystal display device according to the present invention does not need to form an active element such as a TFT, so that it can be manufactured at a high yield and at a relatively low cost. In addition, conventional PALC
Since it does not require a thin dielectric separator like
A large display can be manufactured relatively easily, a driving voltage can be reduced, and a large display device with low power consumption can be provided.

(Embodiment 2) FIG. 6 schematically shows a liquid crystal display device 300 according to the present embodiment. Liquid crystal display device 300
Has a liquid crystal cell 300a and a plasma light emitting cell 300b. Except for the configuration of the liquid crystal cell 300a, the configuration is the same as that of the liquid crystal display device 200 according to the first embodiment.

In the liquid crystal cell 300a, a plurality of parallel striped electrodes 20 are arranged on the surface of the substrate 11 on the liquid crystal layer side. The stripe electrode 20 extends in a direction orthogonal to the signal electrode 22, and the plasma emission channel 25a 'is disposed in parallel with the signal electrode 22 (Ty
pe II). That is, the plasma emission channel 25a 'of the plasma emission cell 300b and the stripe electrode 20 are orthogonal to each other.

The liquid crystal display device 3 of this embodiment (Type II)
00 is basically the same as the liquid crystal display device 200 of the first embodiment (Type I), but since the plasma emission channel 25a 'is arranged in parallel with the signal electrode 22,
The difference is that in order to drive the liquid crystal layer, it is necessary to apply a voltage between each of the striped electrodes 20 and the signal electrode 22.

(Embodiment 3) In the liquid crystal display device of this embodiment, the arrangement of the electrode on the plasma cell side of the liquid crystal layer and the photoconductive layer are different from those of the previous embodiment. Configuration of Electrode and Photoconductive Layer Formed on Plasma Cell Side of Liquid Crystal Layer of Liquid Crystal Display Device According to the Present Embodiment (Address Side Substrate 400 ′)
Is schematically shown in FIG.

A plurality of striped signal electrodes 42 are formed on a substrate 46. A photoconductive layer 41 is formed so as to cover the plurality of striped signal electrodes 42. In the example shown in FIG. 7, an example is shown in which a single photoconductive layer 41 is formed on almost the entire surface so that the photoconductive layer 41 covers all the stripe-shaped signal electrodes 42, but as shown in FIG. Next, a stripe-shaped photoconductive layer 14 '(see FIG.
(A)) or a dot-shaped photoconductive layer 14 ″ (FIG. 5).
(B)) may be formed.

Further, an insulating layer 45 is formed so as to cover the photoconductive layer 41, and a pixel electrode 44 is formed on the insulating layer 45 in a dot shape for each pixel. A contact hole 43 is formed in the insulating layer 45.
The contact hole 43 is at least partially filled with, for example, a material for forming the pixel electrode 44, and the pixel electrode 44 and the photoconductive layer 4 are filled through the contact hole 43.
1 is connected.

The liquid crystal display device of the present embodiment is the same as that of the first embodiment.
It can be formed by a similar method using the same material as described above. Note that the material of the insulating layer is not particularly limited, and widely known organic materials and inorganic materials can be used. Known methods can be used for forming an insulating film and a contact hole.

The principle of operation of the liquid crystal display device 400 according to the present embodiment will be described with reference to FIGS.

The liquid crystal display device 400 includes a liquid crystal cell 400a.
And a plasma light emitting cell 400b. Except for the configuration of the liquid crystal cell 400a, the liquid crystal display device 20 of the first embodiment
Therefore, the same reference numerals are used for components having the same functions, and the description thereof is omitted. Liquid crystal cell 400
a has the address side substrate 400 'shown in FIG.
Here, the plasma emission channel 25a is connected to the signal electrode 42.
The operation of an example configured so as to be orthogonal to (Type I) will be described. The plasma emission channel 25a may be arranged in parallel with the signal electrode 42 (Type II). However, in this case, the counter electrode 12 needs to be a plurality of stripe-shaped electrodes extending in a direction orthogonal to the signal electrodes 42 (see Embodiment 2).

By applying a discharge pulse voltage between the cathode 18a and the anode 18b in the selected plasma emission channel 25a, the plasma emission channel 2
The gas in 5a is ionized and plasma is generated. The plasma generates light of various wavelengths depending on the type and pressure of the gas (FIG. 8A).

This light is applied to the substrate 46 (and the signal electrode 42).
And is applied to the photoconductive layer 41. The photoconductive layer 41a irradiated with light increases its electrical conductivity and becomes a conductor, and the signal electrode 42 and the pixel electrode 44 are electrically connected through the contact hole 43. When a driving voltage is applied between the counter electrode 12 and the signal electrode 42 while the photoconductive layer 41 is in a conductive state, a voltage is applied to the liquid crystal layer 13 between the signal electrode 42 and the counter electrode 12 to correspond to the pixel. The liquid crystal layer 13a in the region to be driven is driven (FIG. 8B).

Next, when the voltage between the cathode 18a and the anode 18b is turned off and the plasma emission is stopped, the electric conductivity of the photoconductive layer 41 is reduced, and the photoconductive layer 41 becomes an insulator.
2 and the pixel electrode 44 are electrically insulated. Signal electrode 4
Since 2 / photoconductive layer 41 / insulating layer 45 / pixel electrode 44 / liquid crystal layer 13 / counter electrode 12 function as a capacitor, a charge corresponding to the previously applied driving voltage is held on pixel electrode 44, The driving state of the liquid crystal layer 13 is maintained (so-called sample hold) (FIG. 8C).
In the state where the plasma emission is stopped (quenching state), even if a driving voltage is applied between the counter electrode 12 and the signal electrode 42,
Since the signal electrode 42 and the pixel electrode 44 are electrically separated from each other, a sufficient voltage is not applied to the liquid crystal layer 13 on the pixel electrode 44 due to capacitance division. In the next frame (or field), during the period in which the plasma emission channel 25a is selected (period of plasma emission), the liquid crystal layer 13
Is applied with a new drive voltage.

In the case of the structure of this embodiment, the liquid crystal layer 1
3 is applied to the signal electrode 42 / photoconductive layer 41 /
Since the capacitance is distributed by the ratio of the capacitance formed by the insulating layer 45 / pixel electrode 44 and the capacitance formed by the pixel electrode 44 / liquid crystal layer 13 / counter electrode 12, the thickness and the dielectric constant of the insulating layer 45 are adjusted. By doing so, a margin for the thickness and permittivity of the photoconductive layer 41 can be increased, which is advantageous in design.

(Embodiment 4) In this embodiment, a reflective liquid crystal display device is manufactured. Since the basic configuration is the same as that of the third embodiment, a detailed description is omitted.

The address-side substrate 400 ″ of the liquid crystal display device according to the fourth embodiment shown in FIG. 9 has a photoconductive layer 41 ′ formed of a material whose electric conductivity changes with respect to visible light (for example, Chemical vapor deposition (CVD) of amorphous silicon
Embodiment 4 is different from Embodiment 4 in that the pixel electrode 44 ′ is formed using a material that reflects visible light (for example, aluminum is formed by a sputtering method). Further, if the spacer 50 made of a polymer material having a light-shielding function (for example, a polymer material containing a black pigment) is formed so as to fill the gap between the pixel electrodes 44 ', extra reflected light from adjacent pixels can be generated. Since this can be prevented, the contrast increases (in FIG. 9, the spacer on the right side of the pixel electrode 44 'is omitted). In addition, instead of using a material that reflects visible light to form a pixel electrode, a reflective film (for example, a dielectric reflective film) may be formed on a transparent pixel electrode.

In the case of using a photoconductive layer whose electric conductivity changes by visible light, the type and gas pressure of the gas sealed in the plasma emission channel are appropriately changed. For example, a mixed gas of neon and xenon having a relatively strong emission intensity of visible light can be used. Alternatively, a gas that emits ultraviolet light and a phosphor that emits visible light in response to ultraviolet light may be used in combination. As these combinations, the combinations used in the PDP can be used. The phosphor may be formed in the plasma emission channel by, for example, coating.

When using visible light as address light, the photoconductive layer may be formed using, for example, cadmium sulfide. Further, an EL element or the like may be used as the address light source. As the combination of the material of the photoconductive layer and the light source for address, various combinations can be used from known materials and light sources.

When a reflective liquid crystal display device is formed, an STN mode liquid crystal layer is used as a liquid crystal layer, so that a liquid crystal display device having a relatively high contrast can be formed using a single polarizing plate. There is an advantage that can be.

(Embodiment 5) In this embodiment, in order to improve the display characteristics of the liquid crystal display device described in Embodiments 3 and 4, the liquid crystal display device further having a storage capacitor electrically connected to the pixel electrode Will be described.

In the liquid crystal display devices according to the third and fourth embodiments, adjustment of the charge holding time (particularly, securing a sufficient holding time) may be problematic. Since the charge retention time is determined by the resistance value of the liquid crystal material, the dielectric constant of the insulating layer or alignment layer used for the element, the cell gap, the resistance value of the transparent electrode, etc., it is extremely difficult to change the retention time. .

Therefore, in the present embodiment, for example, in the liquid crystal display device of the fourth embodiment, the charge holding time can be set by forming a storage capacitor (auxiliary capacitor) electrically connected to the pixel electrode. I do.

FIG. 10 shows a schematic configuration of the address side substrate 500 including the storage capacitor. A plurality of striped signal electrodes 52 are formed on a substrate 56 (corresponding to the substrate 46 of the address side substrate 400 '). A single (or striped) photoconductive layer 51 is formed on the signal electrode 52. The pixel electrode 54 formed on the insulating layer 55 covering the photoconductive layer 51 is connected to the photoconductive layer 51 via the contact hole 53.

A metal wiring 57 and an insulating layer 58 covering the metal wiring 57 are formed between the pixel electrode 54 and the insulating layer 55. The metal wiring 57 / the insulating layer 58 / the pixel electrode 54
Form a storage capacitor. In this example, the metal wiring 57 is formed as a stripe-shaped electrode extending in a direction orthogonal to the signal electrode 52, but is not limited thereto.

The storage capacitor can be formed, for example, as follows. An aluminum layer having a thickness of about 0.1 μm is vapor-deposited on a substrate 56 having a thickness of about 0.7 mm, and is etched into a stripe having a width of about 30 μm to form an aluminum wiring 57.
The obtained aluminum wiring 57 is anodized to form an insulating film (anodized film) 58 on its surface. An ITO having a thickness of about 50 nm is formed by a sputtering method so as to cover them, and is etched in a dot shape to form pixel electrodes 54 arranged in a matrix. The obtained aluminum / aluminum oxide / ITO structure functions as a storage capacitor.

The holding time depends on the width of the aluminum wiring 57 under the pixel electrode 54, the thickness of the insulating layer 58, and the type (the aluminum oxide 57).
It is needless to say that the change can be made by changing silicon nitride or the like further on the surface.

Here, when the aluminum wiring 57 is arranged at a position hidden by the black matrix of the color filter formed on the opposite substrate, the aperture ratio of the liquid crystal display device is not reduced. However, even in the case where the width must be larger than the black matrix due to the requirement of the charge retention time, the decrease in the aperture ratio can be minimized.

(Embodiment 6) In this embodiment, an example will be described in which the configuration of the counter substrate of the liquid crystal display device 400 of Embodiment 3 is improved. Since a transparent conductive material such as ITO has a relatively low electrical conductivity, in a large-sized display device, when the electrode 12 is formed of ITO, a problem such as a delay of a signal voltage, a distortion of a voltage waveform or a decrease in amplitude may occur. is there. In this embodiment, a metal electrode electrically connected to the transparent electrode is formed in order to avoid the above problem. In the following example, an example in which a color filter layer for performing color display is formed is described, but the color filter layer may be omitted. The counter substrate according to the present embodiment and the method for manufacturing the counter substrate will be described with reference to FIG.

A color resist (for example, CR-2000 manufactured by Fuji Hunt Co., Ltd.) is formed on a glass substrate 61 having a thickness of about 1.1 mm.
(Red), CG-2000 (green), CB-2000
(Blue)) and sequentially repeating spinner coating, mask exposure, development, and baking, thereby forming a stripe-shaped color filter layer 62 (for example, R: 62a, G:
62b, B: 62c) are formed (FIGS. 11A and 11B).

Next, an overcoat layer 63 for flattening the substrate surface and protecting the color filter layer 62 is formed of a transparent polymer material (for example, V259-P manufactured by Nippon Steel Chemical Co., Ltd.).
A) (FIG. 11C).

Further, on the overcoat layer 63, for example, a metal electrode 64 of about 0.2 μm
Is formed (FIG. 11D). Since the metal electrode 64 is formed at a position corresponding to the gap between the pixel electrodes (see reference numeral 44 in FIGS. 7 and 8), it also functions as a black matrix. Finally, an ITO film having a thickness of about 50 nm is formed on almost the entire surface to cover the surface of the substrate.
5 is obtained (FIG. 11E).

(Embodiment 7) In Embodiments 3 and 4,
Although the Type II liquid crystal display device has been illustrated, it is needless to say that the Type I liquid crystal display device can be configured with the same configuration as the third and fourth embodiments. The pixel electrode is not selected because the signal electrode and the pixel electrode are coupled by the capacitance formed between the signal electrode and the pixel electrode (signal electrode / insulating layer / photoconductive layer / pixel electrode). Even during the period, the potential of the pixel electrode changes due to the influence of the potential of the signal electrode, the voltage applied to the liquid crystal layer deviates from a desired voltage,
As a result, display quality may be degraded.

In the present embodiment, a configuration example in which the capacitance formed between the signal electrode and the pixel electrode (capacitive coupling between the signal electrode and the pixel electrode) is reduced will be described. here,
Only the configuration of the signal electrode / photoconductive layer / insulating layer / pixel electrode will be described. The configuration of the present embodiment can be applied to the liquid crystal display device of the above embodiment.

FIGS. 12A and 12B schematically show an example of the structure of the pixel electrode / photoconductive layer / signal electrode of the present embodiment. For simplicity, one configuration of a plurality of pixel electrodes formed in a matrix will be described.

The signal electrode 162 is formed on the substrate 166. The width of the signal electrode 162 is smaller than the width of the signal electrode of the previous embodiment so that the capacitance formed between the pixel electrode 164 and the pixel electrode 164 is reduced. A dot-shaped photoconductive layer 161 is formed on the signal electrode 162, and the insulating layer 1 is formed on almost the entire surface of the substrate 166 so as to cover them.
65 has a through hole 163 on the photoconductive layer 161. The dot-shaped photoconductive layer 161 is formed, for example, at the center of the edge on the pixel electrode 164. The configuration of the present embodiment can be manufactured using a known material and a manufacturing method as in the previous embodiment.

Further, for example, when the structure is as shown in FIGS. 13A and 13B, the insulating film can be omitted and the capacitance formed between the signal electrode and the pixel electrode can be reduced. it can.

The signal electrode 72 formed on the substrate 76
The signal electrode 7 is provided between the adjacent pixel electrodes 74.
Part 2 has a T-shaped branched projection 72a.
A dot-shaped photoconductive layer 71 is formed so as to cover the projection 72 a, and the pixel electrode 7 is formed so as to cover the photoconductive layer 71.
4 are formed.

As is apparent from FIG. 13, the signal electrode 72
The region where the capacitor overlaps with the pixel electrode 74 to form a capacitance is limited to the lower part of the projection 72 a of the signal electrode 72. Therefore, the capacitance formed between the signal electrode and the pixel electrode is small. Note that a plurality of dot-shaped photoconductive layers 71 may be formed for one pixel electrode. For example, two photoconductive layers 71
May be formed and connected to the protruding portions of the signal electrode branched into a rectangular shape.

Further, by reducing the area of the photoconductive layer as in the configuration of the present embodiment, it is possible to increase the efficiency of using the address light. A reflection layer is formed on the inner wall of the plasma emission channel, and a member having a condensing function is formed as necessary, so that light generated in the plasma emission channel can be concentrated on the photoconductive layer.

[0086]

As described above, according to the present invention, there is provided a new type of liquid crystal display device which performs addressing by light. Since the liquid crystal display device according to the present invention does not require an active element such as a TFT, it can be manufactured at a high yield at a relatively low cost. Furthermore, because of addressing by light, the extremely thin (about 5
Since a dielectric separator is not required, it is possible to provide a liquid crystal display device that can be manufactured relatively inexpensively with higher yield than conventional PALC and that can be driven at a lower voltage than conventional PALC.

When a backlight is provided in the transmission type display device of the present invention, an ultraviolet absorbing layer (for example, a film made of a polymer) may be added between the backlight and the display device as needed. Further, in the liquid crystal display device according to the present invention, the structure of the liquid crystal layer is not limited (for example, a host-guest type liquid crystal, a cholesteric liquid crystal, a polymer dispersed type liquid crystal, etc.), and widely known liquid crystal layers can be used.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a cross-sectional structure of a conventional PALC.

FIG. 2 is a diagram schematically showing one example of a liquid crystal display device according to the present invention.

FIG. 3 is a cross-sectional view for explaining the operation principle of the liquid crystal display device according to the present invention.

FIG. 4A is a schematic view illustrating an example of a method for manufacturing a liquid crystal display device according to the present invention.

FIG. 4B is a schematic view illustrating an example of a method for manufacturing a liquid crystal display device according to the present invention.

FIG. 4C is a schematic view showing an example of a method for manufacturing a liquid crystal display device according to the present invention.

FIG. 5 is a diagram schematically showing another example of the arrangement of the photoconductive layer in the liquid crystal display device according to the present invention.

FIG. 6 is a diagram schematically showing another example of the liquid crystal display device according to the present invention.

FIG. 7 is a diagram schematically showing another example of the liquid crystal display device according to the present invention.

FIG. 8 is a cross-sectional view for explaining the operation principle of the liquid crystal display device according to the present invention.

FIG. 9 is a diagram schematically showing another example of the liquid crystal display device according to the present invention.

FIG. 10 is a diagram schematically showing a configuration of a storage capacitor in the liquid crystal display device of the present invention.

FIG. 11 is a diagram schematically showing a part of the method for manufacturing the liquid crystal display device of the present invention.

FIG. 12 is a diagram schematically illustrating a configuration example of a signal electrode / photoconductive layer / insulating layer / pixel electrode according to a seventh embodiment. (A)
Is a plan view, and (b) is a sectional view taken along line 12b-12b 'of (a).

FIG. 13 is a diagram schematically illustrating a configuration example of a signal electrode / photoconductive layer / pixel electrode according to a seventh embodiment. (A) is a plan view, and (b) is a cross-sectional view taken along line 13b-13b 'of (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Signal (column) electrode 3 Liquid crystal layer 4 Dielectric separator 5 Plasma discharge channel 6 Rib partition 7 Cathode 8 Anode 9 Glass substrate 10 Scanning (row) electrode 11 Substrate 12 Counter electrode (ITO) 13 Liquid crystal layer 13a Voltage is applied. Liquid crystal layer 14, 14 ', 41 Photoconductive layer 14a, 41a Photoconductive layer irradiated with light 15 Signal electrode 16, 46 Substrate 17, 50 Rib partition 18 Discharge electrode 18a Cathode 18b Anode 19, 46, 56 Substrate 20 Electrode (ITO) 21, 51 Photoconductive layer 22, 42, 52 Signal electrode (striped) 25a Plasma emission channel 43, 53 Contact hole 44, 54 Pixel electrode 45, 55 Insulating layer 57 Metal wiring 58 Insulating layer

Claims (13)

[Claims] A first substrate, a second substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, and a single substrate provided on the liquid crystal layer side of the first substrate. A plurality of signal electrodes provided on the liquid crystal layer side of the second substrate and formed of a transparent conductive material and extending in a first direction and having a stripe shape parallel to each other; and covering the plurality of signal electrodes. A photoconductive layer, and a plurality of stripe-shaped parallel layers provided outside the second substrate and irradiating at least a part of the photoconductive layer with light and extending in a second direction different from the first direction. Switching the plurality of light sources to change the electrical conductivity of the photoconductive layer, and switching the electrical connection between the light-irradiated region of the photoconductive layer and the signal electrode. And
Thereby, a liquid crystal display device that optically addresses the liquid crystal layer. 2. A first substrate, a second substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, and a first substrate provided on the liquid crystal layer side of the first substrate. A plurality of stripe-shaped first electrodes extending in a direction parallel to each other, and provided on the liquid crystal layer side of the second substrate and made of a transparent conductive material and extending in a second direction different from the first direction. A plurality of parallel stripe-shaped signal electrodes; a photoconductive layer covering the plurality of signal electrodes; and a second layer provided outside the second substrate and irradiating at least a part of the photoconductive layer with light. A plurality of stripe-shaped light sources parallel to each other extending in the direction of, the electric conductivity of the photoconductive layer is changed by switching the plurality of light sources, and the light of the photoconductive layer is irradiated with the light. Switching the electrical connection between the region and the signal electrode,
Thereby, a liquid crystal display device that optically addresses the liquid crystal layer. 3. A first substrate, a second substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, and a single substrate provided on the liquid crystal layer side of the first substrate. A plurality of parallel striped signal electrodes provided on the liquid crystal layer side of the second substrate and made of a transparent conductive material and extending in a first direction. An insulating layer formed; a photoconductive layer formed between the plurality of signal electrodes and the insulating layer; and a plurality of photoconductive layers connected to the photoconductive layer via through holes formed in the insulating layer. A plurality of pixel electrodes provided on the outside of the second substrate and irradiating at least a part of the photoconductive layer with light in a stripe shape extending in a second direction different from the first direction. And a light source, wherein the electric conductivity of the photoconductive layer is changed by switching the plurality of light sources. So, switching the electrical connection between the pixel electrode and the signal electrode, by the liquid crystal display device for optically addressing the liquid crystal layer. 4. A first substrate, a second substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, and a first substrate provided on the liquid crystal layer side of the first substrate. A plurality of stripe-shaped first electrodes extending in a direction parallel to each other, and provided on the liquid crystal layer side of the second substrate and made of a transparent conductive material and extending in a second direction different from the first direction. A plurality of parallel striped signal electrodes; an insulating layer formed on the plurality of signal electrodes; a photoconductive layer formed between the plurality of signal electrodes and the insulating layer; A plurality of pixel electrodes connected to the photoconductive layer via the formed through holes; and a second electrode provided outside the second substrate and irradiating at least a part of the photoconductive layer with light. And a plurality of stripe-shaped light sources parallel to each other extending in the direction of. Photoconductive layer changing the electric conductivity of, switching the electrical connection between the light irradiated area and the signal electrode of the photoconductive layer by,
Thereby, a liquid crystal display device that optically addresses the liquid crystal layer. 5. The liquid crystal display device according to claim 3, wherein the photoconductive layer has at least one dot-shaped photoconductive film disposed for each of the plurality of pixel electrodes. 6. The liquid crystal display device according to claim 3, further comprising a storage capacitor electrically connected to said pixel electrode. 7. The device according to claim 1, wherein the first electrode is formed of a transparent conductive layer, and the first electrode layer further includes a metal electrode electrically connected to the first electrode. Liquid crystal display. 8. The liquid crystal display device according to claim 1, wherein the photoconductive layer includes a substance whose electric conductivity changes by ultraviolet light, and performs display in a transmission mode or a reflection mode. 9. The photoconductive layer includes a substance whose electric conductivity changes by visible light, and performs display in a reflection mode.
The liquid crystal display device according to claim 1. 10. The liquid crystal display device according to claim 1, wherein the photoconductive layer is a single photoconductive film. 11. The liquid crystal display device according to claim 1, wherein the photoconductive layer is formed of a plurality of striped photoconductive films parallel to the plurality of striped signal electrodes. . 12. The liquid crystal display device according to claim 1, wherein the plurality of light sources have a plasma emission channel filled with an ionizable gas. 13. The liquid crystal display device according to claim 12, wherein the plurality of light sources further include a phosphor that converts ultraviolet light generated from the plasma emission channel into visible light.